National Library of Energy BETA

Sample records for amorphous silicon a-si

  1. Atmospheric Pressure Plasma CVD of Amorphous Hydrogenated Silicon Carbonitride (a-SiCN:H) Films Using Triethylsilane and Nitrogen

    SciTech Connect (OSTI)

    Srinivasan Guruvenket; Steven Andrie; Mark Simon; Kyle W. Johnson; Robert A. Sailer

    2011-10-04

    Amorphous hydrogenated silicon carbonitride (a-SiCN:H) thin films are synthesized by atmospheric pressure plasma enhanced chemical vapor (AP-PECVD) deposition using the Surfx Atomflow{trademark} 250D APPJ source with triethylsilane (HSiEt{sub 3}, TES) and nitrogen as the precursor and the reactive gases, respectively. The effect of the substrate temperature (T{sub s}) on the growth characteristics and the properties of a-SiCN:H films was evaluated. The properties of the films were investigated via scanning electron microscopy (SEM), atomic force microscopy (AFM) for surface morphological analyses, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) for chemical and compositional analyses; spectroscopic ellipsometry for optical properties and thickness determination and nanoindentation to determine the mechanical properties of the a-SiCN:H films. Films deposited at low T{sub s} depict organic like features, while the films deposited at high T{sub s} depict ceramic like features. FTIR and XPS studies reveal that an increases in T{sub s} helps in the elimination of organic moieties and incorporation of nitrogen in the film. Films deposited at T{sub s} of 425 C have an index of refraction (n) of 1.84 and hardness (H) of 14.8 GPa. A decrease in the deposition rate between T{sub s} of 25 and 250 C and increase in deposition rate between T{sub s} of 250 and 425 C indicate that the growth of a-SiCN:H films at lower T{sub s} are surface reaction controlled, while at high temperatures film growth is mass-transport controlled. Based on the experimental results, a potential route for film growth is proposed.

  2. Amorphous silicon ionizing particle detectors

    DOE Patents [OSTI]

    Street, R.A.; Mendez, V.P.; Kaplan, S.N.

    1988-11-15

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation. 15 figs.

  3. Amorphous silicon ionizing particle detectors

    DOE Patents [OSTI]

    Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

    1988-01-01

    Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

  4. Amorphous silicon photovoltaic devices

    DOE Patents [OSTI]

    Carlson, David E.; Lin, Guang H.; Ganguly, Gautam

    2004-08-31

    This invention is a photovoltaic device comprising an intrinsic or i-layer of amorphous silicon and where the photovoltaic device is more efficient at converting light energy to electric energy at high operating temperatures than at low operating temperatures. The photovoltaic devices of this invention are suitable for use in high temperature operating environments.

  5. Amorphous silicon radiation detectors

    DOE Patents [OSTI]

    Street, R.A.; Perez-Mendez, V.; Kaplan, S.N.

    1992-11-17

    Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification. 13 figs.

  6. Amorphous silicon radiation detectors

    DOE Patents [OSTI]

    Street, Robert A.; Perez-Mendez, Victor; Kaplan, Selig N.

    1992-01-01

    Hydrogenated amorphous silicon radiation detector devices having enhanced signal are disclosed. Specifically provided are transversely oriented electrode layers and layered detector configurations of amorphous silicon, the structure of which allow high electric fields upon application of a bias thereby beneficially resulting in a reduction in noise from contact injection and an increase in signal including avalanche multiplication and gain of the signal produced by incoming high energy radiation. These enhanced radiation sensitive devices can be used as measuring and detection means for visible light, low energy photons and high energy ionizing particles such as electrons, x-rays, alpha particles, beta particles and gamma radiation. Particular utility of the device is disclosed for precision powder crystallography and biological identification.

  7. Direct-patterned optical waveguides on amorphous silicon films

    DOE Patents [OSTI]

    Vernon, Steve; Bond, Tiziana C.; Bond, Steven W.; Pocha, Michael D.; Hau-Riege, Stefan

    2005-08-02

    An optical waveguide structure is formed by embedding a core material within a medium of lower refractive index, i.e. the cladding. The optical index of refraction of amorphous silicon (a-Si) and polycrystalline silicon (p-Si), in the wavelength range between about 1.2 and about 1.6 micrometers, differ by up to about 20%, with the amorphous phase having the larger index. Spatially selective laser crystallization of amorphous silicon provides a mechanism for controlling the spatial variation of the refractive index and for surrounding the amorphous regions with crystalline material. In cases where an amorphous silicon film is interposed between layers of low refractive index, for example, a structure comprised of a SiO.sub.2 substrate, a Si film and an SiO.sub.2 film, the formation of guided wave structures is particularly simple.

  8. Compensated amorphous silicon solar cell

    DOE Patents [OSTI]

    Carlson, David E.

    1980-01-01

    An amorphous silicon solar cell incorporates a region of intrinsic hydrogenated amorphous silicon fabricated by a glow discharge wherein said intrinsic region is compensated by P-type dopants in an amount sufficient to reduce the space charge density of said region under illumination to about zero.

  9. Compensated amorphous silicon solar cell

    DOE Patents [OSTI]

    Devaud, Genevieve

    1983-01-01

    An amorphous silicon solar cell including an electrically conductive substrate, a layer of glow discharge deposited hydrogenated amorphous silicon over said substrate and having regions of differing conductivity with at least one region of intrinsic hydrogenated amorphous silicon. The layer of hydrogenated amorphous silicon has opposed first and second major surfaces where the first major surface contacts the electrically conductive substrate and an electrode for electrically contacting the second major surface. The intrinsic hydrogenated amorphous silicon region is deposited in a glow discharge with an atmosphere which includes not less than about 0.02 atom percent mono-atomic boron. An improved N.I.P. solar cell is disclosed using a BF.sub.3 doped intrinsic layer.

  10. Three dimensional amorphous silicon/microcrystalline silicon solar cells

    DOE Patents [OSTI]

    Kaschmitter, James L.

    1996-01-01

    Three dimensional deep contact amorphous silicon/microcrystalline silicon (a-Si/.mu.c-Si) solar cells which use deep (high aspect ratio) p and n contacts to create high electric fields within the carrier collection volume material of the cell. The deep contacts are fabricated using repetitive pulsed laser doping so as to create the high aspect p and n contacts. By the provision of the deep contacts which penetrate the electric field deep into the material where the high strength of the field can collect many of the carriers, thereby resulting in a high efficiency solar cell.

  11. Three dimensional amorphous silicon/microcrystalline silicon solar cells

    DOE Patents [OSTI]

    Kaschmitter, J.L.

    1996-07-23

    Three dimensional deep contact amorphous silicon/microcrystalline silicon (a-Si/{micro}c-Si) solar cells are disclosed which use deep (high aspect ratio) p and n contacts to create high electric fields within the carrier collection volume material of the cell. The deep contacts are fabricated using repetitive pulsed laser doping so as to create the high aspect p and n contacts. By the provision of the deep contacts which penetrate the electric field deep into the material where the high strength of the field can collect many of the carriers, thereby resulting in a high efficiency solar cell. 4 figs.

  12. Cermet layer for amorphous silicon solar cells

    DOE Patents [OSTI]

    Hanak, Joseph J.

    1979-01-01

    A transparent high work function metal cermet forms a Schottky barrier in a Schottky barrier amorphous silicon solar cell and adheres well to the P+ layer in a PIN amorphous silicon solar cell.

  13. Tandem junction amorphous silicon solar cells

    DOE Patents [OSTI]

    Hanak, Joseph J.

    1981-01-01

    An amorphous silicon solar cell has an active body with two or a series of layers of hydrogenated amorphous silicon arranged in a tandem stacked configuration with one optical path and electrically interconnected by a tunnel junction. The layers of hydrogenated amorphous silicon arranged in tandem configuration can have the same bandgap or differing bandgaps.

  14. High resolution amorphous silicon radiation detectors

    DOE Patents [OSTI]

    Street, Robert A.; Kaplan, Selig N.; Perez-Mendez, Victor

    1992-01-01

    A radiation detector employing amorphous Si:H cells in an array with each detector cell having at least three contiguous layers (n type, intrinsic, p type), positioned between two electrodes to which a bias voltage is applied. An energy conversion layer atop the silicon cells intercepts incident radiation and converts radiation energy to light energy of a wavelength to which the silicon cells are responsive. A read-out device, positioned proximate to each detector element in an array allows each such element to be interrogated independently to determine whether radiation has been detected in that cell. The energy conversion material may be a layer of luminescent material having a columnar structure. In one embodiment a column of luminescent material detects the passage therethrough of radiation to be detected and directs a light beam signal to an adjacent a-Si:H film so that detection may be confined to one or more such cells in the array. One or both electrodes may have a comb structure, and the teeth of each electrode comb may be interdigitated for capacitance reduction. The amorphous Si:H film may be replaced by an amorphous Si:Ge:H film in which up to 40 percent of the amorphous material is Ge. Two dimensional arrays may be used in X-ray imaging, CT scanning, crystallography, high energy physics beam tracking, nuclear medicine cameras and autoradiography.

  15. High resolution amorphous silicon radiation detectors

    DOE Patents [OSTI]

    Street, R.A.; Kaplan, S.N.; Perez-Mendez, V.

    1992-05-26

    A radiation detector employing amorphous Si:H cells in an array with each detector cell having at least three contiguous layers (n-type, intrinsic, p-type), positioned between two electrodes to which a bias voltage is applied. An energy conversion layer atop the silicon cells intercepts incident radiation and converts radiation energy to light energy of a wavelength to which the silicon cells are responsive. A read-out device, positioned proximate to each detector element in an array allows each such element to be interrogated independently to determine whether radiation has been detected in that cell. The energy conversion material may be a layer of luminescent material having a columnar structure. In one embodiment a column of luminescent material detects the passage therethrough of radiation to be detected and directs a light beam signal to an adjacent a-Si:H film so that detection may be confined to one or more such cells in the array. One or both electrodes may have a comb structure, and the teeth of each electrode comb may be interdigitated for capacitance reduction. The amorphous Si:H film may be replaced by an amorphous Si:Ge:H film in which up to 40 percent of the amorphous material is Ge. Two dimensional arrays may be used in X-ray imaging, CT scanning, crystallography, high energy physics beam tracking, nuclear medicine cameras and autoradiography. 18 figs.

  16. Amorphous silicon passivated contacts for diffused junction silicon solar cells

    SciTech Connect (OSTI)

    Bullock, J. Yan, D.; Wan, Y.; Cuevas, A.; Demaurex, B.; Hessler-Wyser, A.; De Wolf, S.

    2014-04-28

    Carrier recombination at the metal contacts is a major obstacle in the development of high-performance crystalline silicon homojunction solar cells. To address this issue, we insert thin intrinsic hydrogenated amorphous silicon [a-Si:H(i)] passivating films between the dopant-diffused silicon surface and aluminum contacts. We find that with increasing a-Si:H(i) interlayer thickness (from 0 to 16?nm) the recombination loss at metal-contacted phosphorus (n{sup +}) and boron (p{sup +}) diffused surfaces decreases by factors of ?25 and ?10, respectively. Conversely, the contact resistivity increases in both cases before saturating to still acceptable values of ? 50 m? cm{sup 2} for n{sup +} and ?100 m? cm{sup 2} for p{sup +} surfaces. Carrier transport towards the contacts likely occurs by a combination of carrier tunneling and aluminum spiking through the a-Si:H(i) layer, as supported by scanning transmission electron microscopyenergy dispersive x-ray maps. We explain the superior contact selectivity obtained on n{sup +} surfaces by more favorable band offsets and capture cross section ratios of recombination centers at the c-Si/a-Si:H(i) interface.

  17. Narrow band gap amorphous silicon semiconductors

    DOE Patents [OSTI]

    Madan, A.; Mahan, A.H.

    1985-01-10

    Disclosed is a narrow band gap amorphous silicon semiconductor comprising an alloy of amorphous silicon and a band gap narrowing element selected from the group consisting of Sn, Ge, and Pb, with an electron donor dopant selected from the group consisting of P, As, Sb, Bi and N. The process for producing the narrow band gap amorphous silicon semiconductor comprises the steps of forming an alloy comprising amorphous silicon and at least one of the aforesaid band gap narrowing elements in amount sufficient to narrow the band gap of the silicon semiconductor alloy below that of amorphous silicon, and also utilizing sufficient amounts of the aforesaid electron donor dopant to maintain the amorphous silicon alloy as an n-type semiconductor.

  18. Amorphous silicon solar cell allowing infrared transmission

    DOE Patents [OSTI]

    Carlson, David E.

    1979-01-01

    An amorphous silicon solar cell with a layer of high index of refraction material or a series of layers having high and low indices of refraction material deposited upon a transparent substrate to reflect light of energies greater than the bandgap energy of the amorphous silicon back into the solar cell and transmit solar radiation having an energy less than the bandgap energy of the amorphous silicon.

  19. The future of amorphous silicon photovoltaic technology

    SciTech Connect (OSTI)

    Crandall, R; Luft, W

    1995-06-01

    Amorphous silicon modules are commercially available. They are the first truly commercial thin-film photovoltaic (PV) devices. Well-defined production processes over very large areas (>1 m{sup 2}) have been implemented. There are few environmental issues during manufacturing, deployment in the field, or with the eventual disposal of the modules. Manufacturing safety issues are well characterized and controllable. The highest measured initial efficiency to date is 13.7% for a small triple-stacked cell and the highest stabilized module efficiency is 10%. There is a consensus among researchers, that in order to achieve a 15% stabilized efficiency, a triple-junction amorphous silicon structure is required. Fundamental improvements in alloys are needed for higher efficiencies. This is being pursued through the DOE/NREL Thin-Film Partnership Program. Cost reductions through improved manufacturing processes are being pursued under the National Renewable Energy Laboratory/US Department of Energy (NREL/DOE)-sponsored research in manufacturing technology (PVMaT). Much of the work in designing a-Si devices is a result of trying to compensate for the Staebler-Wronski effect. Some new deposition techniques hold promise because they have produced materials with lower stabilized defect densities. However, none has yet produced a high efficiency device and shown it to be more stable than those from standard glow discharge deposited material.

  20. Compensated amorphous-silicon solar cell

    DOE Patents [OSTI]

    Devaud, G.

    1982-06-21

    An amorphous silicon solar cell including an electrically conductive substrate, a layer of glow discharge deposited hydrogenated amorphous silicon having regions of differing conductivity with at least one region of intrinsic hydrogenated amorphous silicon. The layer of hydrogenated amorphous silicon has opposed first and second major surfaces where the first major surface contacts the elecrically conductive substrate and an electrode for electrically contacting the second major surface. The intrinsic hydrogenated amorphous silicon region is deposited in a glow discharge with an atmosphere which includes not less than about 0.02 atom percent mono-atomic boron. An improved N.I.P. solar cell is disclosed using a BF/sub 3/ doped intrinsic layer.

  1. Method of producing hydrogenated amorphous silicon film

    DOE Patents [OSTI]

    Wiesmann, Harold J.

    1980-01-01

    This invention relates to hydrogenated amorphous silicon produced by thermally decomposing silane (SiH.sub.4) or other gases comprising H and Si, from a tungsten or carbon foil heated to a temperature of about 1400.degree.-1600.degree. C., in a vacuum of about 10.sup.-6 to 19.sup.-4 torr, to form a gaseous mixture of atomic hydrogen and atomic silicon, and depositing said gaseos mixture onto a substrate independent of and outside said source of thermal decomposition, to form hydrogenated amorphous silicon. The presence of an ammonia atmosphere in the vacuum chamber enhances the photoconductivity of the hydrogenated amorphous silicon film.

  2. Properties of hydrogenated amorphous silicon produced at high temperature

    SciTech Connect (OSTI)

    Crandall, R.S.; Mahan, A.H.; Nelson, B. ); Vanecek, M. ); Balberg, I. )

    1992-12-01

    A comprehensive study of hydrogenated amorphous silicon ([ital a]-Si:H) deposited by hot wire and conventional glow discharge suggests that temperatures above the so called optimum 250 [degree]C substrate temperature can produce device-quality films. These films show enhanced transport properties and improved structural order. In addition we show that hot wire material can be produced with just as many hydrogen atoms as are needed to passivate most of the dangling bonds present in unhydrogenated [ital a]-Si:H.

  3. Deposition of device quality low H content, amorphous silicon films

    DOE Patents [OSTI]

    Mahan, Archie H.; Carapella, Jeffrey C.; Gallagher, Alan C.

    1995-01-01

    A high quality, low hydrogen content, hydrogenated amorphous silicon (a-Si:H) film is deposited by passing a stream of silane gas (SiH.sub.4) over a high temperature, 2000.degree. C., tungsten (W) filament in the proximity of a high temperature, 400.degree. C., substrate within a low pressure, 8 mTorr, deposition chamber. The silane gas is decomposed into atomic hydrogen and silicon, which in turn collides preferably not more than 20-30 times before being deposited on the hot substrate. The hydrogenated amorphous silicon films thus produced have only about one atomic percent hydrogen, yet have device quality electrical, chemical, and structural properties, despite this lowered hydrogen content.

  4. Deposition of device quality low H content, amorphous silicon films

    DOE Patents [OSTI]

    Mahan, A.H.; Carapella, J.C.; Gallagher, A.C.

    1995-03-14

    A high quality, low hydrogen content, hydrogenated amorphous silicon (a-Si:H) film is deposited by passing a stream of silane gas (SiH{sub 4}) over a high temperature, 2,000 C, tungsten (W) filament in the proximity of a high temperature, 400 C, substrate within a low pressure, 8 mTorr, deposition chamber. The silane gas is decomposed into atomic hydrogen and silicon, which in turn collides preferably not more than 20--30 times before being deposited on the hot substrate. The hydrogenated amorphous silicon films thus produced have only about one atomic percent hydrogen, yet have device quality electrical, chemical, and structural properties, despite this lowered hydrogen content. 7 figs.

  5. New results on the microstructure of amorphous silicon as observed by internal friction

    SciTech Connect (OSTI)

    Crandall, R.S.; Mahan, A.H.; Iwaniczko, E.; Jones, K.M.; Liu, X.; White, B.E. Jr.; Pohl, R.O.

    1997-07-01

    The authors have measured the low temperature internal friction (Q{sup {minus}1}) of amorphous silicon (a-Si) films. Electron-beam evaporation leads to the well-known temperature-independent Q{sub 0}{sup {minus}1} plateau common to all amorphous solids. For hydrogenated amorphous silicon (a-Si:H) with about 1 at.% H produced by hot wire chemical vapor deposition, however, the value of Q{sub 0}{sup {minus}1} is over two hundred times smaller than for e-beam a-Si. This is the first observation of an amorphous solid without any significant low energy excitations. This finding offers the opportunity to study amorphous solids containing controlled densities of tunneling defects, and thus to explore their nature.

  6. The reliability and stability of multijunction amorphous silicon PV modules

    SciTech Connect (OSTI)

    Carlson, D.E.

    1995-11-01

    Solarex is developing a manufacturing process for the commercial production of 8 ft{sup 2} multijunction amorphous silicon (a-Si) PV modules starting in 1996. The device structure used in these multijunction modules is: glass/textured tin oxide/p-i-n/p-i-n/ZnO/Al/EVA/Tedlar where the back junction of the tandem structure contains an amorphous silicon germanium alloy. As an interim step, 4 ft{sup 2} multijunction modules have been fabricated in a pilot production mode over the last several months. The distribution of initial conversion efficiencies for an engineering run of 67 modules (4 ft{sup 2}) is shown. Measurements recently performed at NREL indicate that the actual efficiencies are about 5% higher than those shown, and thus exhibit an average initial conversion efficiency of about 9.5%. The data indicates that the process is relatively robust since there were no modules with initial efficiencies less than 7.5%.

  7. Hydrogenated amorphous silicon barriers for niobium-niobium Josephson junctions

    SciTech Connect (OSTI)

    Kroger, H.; Aucoin, R.; Currier, L.W.; Jillie, D.W.; Potter, C.N.; Shaw, D.W.; Smith, L.N.; Thaxter, J.B.; Willis, P.H.

    1985-03-01

    The authors report on further studies of the effects of hydrogenation of sputtered amorphous silicon barriers upon the current-voltage (I-V) characteristics of Nb-Nb Josephson tunnel junctions. For composite trilayer barriers (a-Si/a-Si:H/a-Si) which are deposited using 8 mT of Ar, we find that there is an abrupt improvement in device characteristics when the central hydrogenated layer is deposited using a hydrogen partial pressure which exceeds about 0.5 mT. They attribute this to the reduction in the density of localized states in the a-Si:H layer. We have observed excellent I-V characteristics with trilayer barrier devices whose central hydrogenated layer is only about 1/7 of the thickness of the entire barrier. This observation suggests that localized states near the geometric center of the barrier are the most significant in degrading device characteristics. Annealing experiments and published data on the diffusion of deuterium in a-Si suggest that the composite barriers will be extremely stable during processing and storage. Zero bias anomalies in device I-V characteristics and spin density in the a-Si and a-Si:H layers have been measured.

  8. Neutron irradiation induced amorphization of silicon carbide

    SciTech Connect (OSTI)

    Snead, L.L.; Hay, J.C.

    1998-09-01

    This paper provides the first known observation of silicon carbide fully amorphized under neutron irradiation. Both high purity single crystal hcp and high purity, highly faulted (cubic) chemically vapor deposited (CVD) SiC were irradiated at approximately 60 C to a total fast neutron fluence of 2.6 {times} 10{sup 25} n/m{sup 2}. Amorphization was seen in both materials, as evidenced by TEM, electron diffraction, and x-ray diffraction techniques. Physical properties for the amorphized single crystal material are reported including large changes in density ({minus}10.8%), elastic modulus as measured using a nanoindentation technique ({minus}45%), hardness as measured by nanoindentation ({minus}45%), and standard Vickers hardness ({minus}24%). Similar property changes are observed for the critical temperature for amorphization at this neutron dose and flux, above which amorphization is not possible, is estimated to be greater than 130 C.

  9. An amorphous phase formation at palladium / silicon oxide (Pd...

    Office of Scientific and Technical Information (OSTI)

    An amorphous phase formation at palladium silicon oxide (PdSiOsub x) interface ... Title: An amorphous phase formation at palladium silicon oxide (PdSiOsub x) interface ...

  10. Inverted amorphous silicon solar cell utilizing cermet layers

    DOE Patents [OSTI]

    Hanak, Joseph J.

    1979-01-01

    An amorphous silicon solar cell incorporating a transparent high work function metal cermet incident to solar radiation and a thick film cermet contacting the amorphous silicon opposite to said incident surface.

  11. Metal electrode for amorphous silicon solar cells

    DOE Patents [OSTI]

    Williams, Richard

    1983-01-01

    An amorphous silicon solar cell having an N-type region wherein the contact to the N-type region is composed of a material having a work function of about 3.7 electron volts or less. Suitable materials include strontium, barium and magnesium and rare earth metals such as gadolinium and yttrium.

  12. Research on stable, high-efficiency amorphous silicon multijunction modules

    SciTech Connect (OSTI)

    Ghosh, M.; DelCueto, J.: Kampas, F.; Xi, J. )

    1993-02-01

    This report describes results from the first phase of a three-phase contract for the development of stable, high-efficiency, same-band-gap, amorphous silicon (a-Si) multijunction photovoltaic (PV) modules. The program involved improving the properties of individual layers of semiconductor and non-semiconductor materials and small-area single-junction and multijunction devices, as well as the multijunction modules. The semiconductor materials research was performed on a-Si p, i, and n layers, and on microcrystalline silicon n layers. These were deposited using plasma-enhanced chemical vapor deposition. The non-semiconductor materials studied were tin oxide, for use as a transparent-conducting-oxide (TCO), and zinc oxide, for use as a back reflector and as a buffer layer between the TCO and the semiconductor layers. Tin oxide was deposited using atmospheric-pressure chemical vapor deposition. Zinc oxide was deposited using magnetron sputtering. The research indicated that the major challenge in the fabrication of a-Si multijunction PV modules is the contact between the two p-i-n cells. A structure that has low optical absorption but that also facilitates the recombination of electrons from the first p-i-n structure with holes from the second p-i-n structure is required. Non-semiconductor layers and a-Si semiconductor layers were tested without achieving the desired result.

  13. Fabricating amorphous silicon solar cells by varying the temperature _of the substrate during deposition of the amorphous silicon layer

    DOE Patents [OSTI]

    Carlson, David E.

    1982-01-01

    An improved process for fabricating amorphous silicon solar cells in which the temperature of the substrate is varied during the deposition of the amorphous silicon layer is described. Solar cells manufactured in accordance with this process are shown to have increased efficiencies and fill factors when compared to solar cells manufactured with a constant substrate temperature during deposition of the amorphous silicon layer.

  14. Crystalline to amorphous transformation in silicon

    SciTech Connect (OSTI)

    Cheruvu, S.M.

    1982-09-01

    In the present investigation, an attempt was made to understand the fundamental mechanism of crystalline-to-amorphous transformation in arsenic implanted silicon using high resolution electron microscopy. A comparison of the gradual disappearance of simulated lattice fringes with increasing Frenkel pair concentration with the experimental observation of sharp interfaces between crystalline and amorphous regions was carried out leading to the conclusion that when the defect concentration reaches a critical value, the crystal does relax to an amorphous state. Optical diffraction experiments using atomic models also supported this hypothesis. Both crystalline and amorphous zones were found to co-exist with sharp interfaces at the atomic level. Growth of the amorphous fraction depends on the temperature, dose rate and the mass of the implanted ion. Preliminary results of high energy electron irradiation experiments at 1.2 MeV also suggested that clustering of point defects occurs near room temperature. An observation in a high resolution image of a small amorphous zone centered at the core of a dislocation is presented as evidence that the nucleation of an amorphous phase is heterogeneous in nature involving clustering or segregation of point defects near existing defects.

  15. Amorphous Silicon Carbide Passivating Layers to Enable Higher Processing Temperature in Crystalline Silicon Heterojunction Solar Cells

    SciTech Connect (OSTI)

    Boccard, Mathieu; Holman, Zachary

    2015-04-06

    "Very efficient crystalline silicon (c-Si) solar cells have been demonstrated when thin layers of intrinsic and doped hydrogenated amorphous silicon (a-Si:H) are used for passivation and carrier selectivity in a heterojunction device. One limitation of this device structure is the (parasitic) absorption in the front passivation/collection a-Si:H layers; another is the degradation of the a-Si:H-based passivation upon temperature, limiting the post-processes to approximately 200°C thus restricting the contacting possibilities and potential tandem device fabrication. To alleviate these two limitations, we explore the potential of amorphous silicon carbide (a-SiC:H), a widely studied material in use in standard a-Si:H thin-film solar cells, which is known for its wider bandgap, increased hydrogen content and stronger hydrogen bonding compared to a-Si:H. We study the surface passivation of solar-grade textured n-type c-Si wafers for symmetrical stacks of 10-nm-thick intrinsic a-SiC:H with various carbon content followed by either p-doped or n-doped a-Si:H (referred to as i/p or i/n stacks). For both doping types, passivation (assessed through carrier lifetime measurements) is degraded by increasing the carbon content in the intrinsic a-SiC:H layer. Yet, this hierarchy is reversed after annealing at 350°C or more due to drastic passivation improvements upon annealing when an a-SiC:H layer is used. After annealing at 350°C, lifetimes of 0.4 ms and 2.0 ms are reported for i/p and i/n stacks, respectively, when using an intrinsic a-SiC:H layer with approximately 10% of carbon (initial lifetimes of 0.3 ms and 0.1 ms, respectively, corresponding to a 30% and 20-fold increase, respectively). For stacks of pure a-Si:H material the lifetimes degrade from 1.2 ms and 2.0 ms for i/p and i/n stacks, respectively, to less than 0.1 ms and 1.1 ms (12-fold and 2-fold decrease, respectively). For complete solar cells using pure a-Si:H i/p and i/n stacks, the open-circuit voltage (Voc

  16. Passivation of c-Si surfaces by sub-nm amorphous silicon capped with silicon nitride

    SciTech Connect (OSTI)

    Wan, Yimao Yan, Di; Bullock, James; Zhang, Xinyu; Cuevas, Andres

    2015-12-07

    A sub-nm hydrogenated amorphous silicon (a-Si:H) film capped with silicon nitride (SiN{sub x}) is shown to provide a high level passivation to crystalline silicon (c-Si) surfaces. When passivated by a 0.8 nm a-Si:H/75 nm SiN{sub x} stack, recombination current density J{sub 0} values of 9, 11, 47, and 87 fA/cm{sup 2} are obtained on 10 Ω·cm n-type, 0.8 Ω·cm p-type, 160 Ω/sq phosphorus-diffused, and 120 Ω/sq boron-diffused silicon surfaces, respectively. The J{sub 0} on n-type 10 Ω·cm wafers is further reduced to 2.5 ± 0.5 fA/cm{sup 2} when the a-Si:H film thickness exceeds 2.5 nm. The passivation by the sub-nm a-Si:H/SiN{sub x} stack is thermally stable at 400 °C in N{sub 2} for 60 min on all four c-Si surfaces. Capacitance–voltage measurements reveal a reduction in interface defect density and film charge density with an increase in a-Si:H thickness. The nearly transparent sub-nm a-Si:H/SiN{sub x} stack is thus demonstrated to be a promising surface passivation and antireflection coating suitable for all types of surfaces encountered in high efficiency c-Si solar cells.

  17. Advances in amorphous silicon photovoltaic technology

    SciTech Connect (OSTI)

    Carlson, D.E.; Rajan, K.; Arya, R.R.; Willing, F.; Yang, L.

    1998-10-01

    With the advent of new multijunction thin film solar cells, amorphous silicon photovoltaic technology is undergoing a commercial revival with about 30 megawatts of annual capacity coming on-line in the next year. These new {ital a}{endash}Si multijunction modules should exhibit stabilized conversion efficiencies on the order of 8{percent}, and efficiencies over 10{percent} may be obtained in the next several years. The improved performance results from the development of amorphous and microcrystalline silicon alloy films with improved optoelectronic properties and from the development of more efficient device structures. Moreover, the manufacturing costs for these multijunction modules using the new large-scale plants should be on the order of {dollar_sign}1 per peak watt. These new modules may find widespread use in solar farms, photovoltaic roofing, as well as in traditional remote applications. {copyright} {ital 1998 Materials Research Society.}

  18. NMR Studies of Molecular Hydrogen in Hydrogenated Amorphous Silicon

    SciTech Connect (OSTI)

    Su, T.; Chen, S.; Taylor, P. C.; Crandall, R. S.; Mahan, A. H.

    2000-01-01

    Using NMR, the concentrations of molecular hydrogen have been measured directly in hydrogenated amorphous silicon made by the hot wire chemical vapor deposition (HWCVD) technique.

  19. Crystallization and doping of amorphous silicon on low temperature plastic

    DOE Patents [OSTI]

    Kaschmitter, J.L.; Truher, J.B.; Weiner, K.H.; Sigmon, T.W.

    1994-09-13

    A method or process of crystallizing and doping amorphous silicon (a-Si) on a low-temperature plastic substrate using a short pulsed high energy source in a selected environment, without heat propagation and build-up in the substrate is disclosed. The pulsed energy processing of the a-Si in a selected environment, such as BF3 and PF5, will form a doped micro-crystalline or poly-crystalline silicon (pc-Si) region or junction point with improved mobilities, lifetimes and drift and diffusion lengths and with reduced resistivity. The advantage of this method or process is that it provides for high energy materials processing on low cost, low temperature, transparent plastic substrates. Using pulsed laser processing a high (>900 C), localized processing temperature can be achieved in thin films, with little accompanying temperature rise in the substrate, since substrate temperatures do not exceed 180 C for more than a few microseconds. This method enables use of plastics incapable of withstanding sustained processing temperatures (higher than 180 C) but which are much lower cost, have high tolerance to ultraviolet light, have high strength and good transparency, compared to higher temperature plastics such as polyimide. 5 figs.

  20. Crystallization and doping of amorphous silicon on low temperature plastic

    DOE Patents [OSTI]

    Kaschmitter, James L.; Truher, Joel B.; Weiner, Kurt H.; Sigmon, Thomas W.

    1994-01-01

    A method or process of crystallizing and doping amorphous silicon (a-Si) on a low-temperature plastic substrate using a short pulsed high energy source in a selected environment, without heat propagation and build-up in the substrate. The pulsed energy processing of the a-Si in a selected environment, such as BF3 and PF5, will form a doped micro-crystalline or poly-crystalline silicon (pc-Si) region or junction point with improved mobilities, lifetimes and drift and diffusion lengths and with reduced resistivity. The advantage of this method or process is that it provides for high energy materials processing on low cost, low temperature, transparent plastic substrates. Using pulsed laser processing a high (>900.degree. C.), localized processing temperature can be achieved in thin films, with little accompanying temperature rise in the substrate, since substrate temperatures do not exceed 180.degree. C. for more than a few microseconds. This method enables use of plastics incapable of withstanding sustained processing temperatures (higher than 180.degree. C.) but which are much lower cost, have high tolerance to ultraviolet light, have high strength and good transparency, compared to higher temperature plastics such as polyimide.

  1. Subtleties of capacitance transients in amorphous silicon

    SciTech Connect (OSTI)

    Crandall, R.S.; Lips, K.

    1996-12-31

    Using junction capacitance methods, the authors describe the effect of contacts on charge emission transients in n-type hydrogenated amorphous silicon. The results demonstrate some of the difficulties encountered in observing and interpreting anomalous temperature independent emission transients (slow relaxation). In this paper, the authors present additional data and reconcile the absence of anomalous emission transients in some cases with a discussion of the dynamics of depletion width filling. The authors show that the transient capacitance response of Schottky structure is not only related to the contact configuration but is connected to the rate of charge injection into the depletion region.

  2. Amorphous silicon solar cells techniques for reactive conditions

    SciTech Connect (OSTI)

    Shimizu, Satoshi; Okawa, Kojiro; Kamiya, Toshio; Fortmann, C.M.; Shimizu, Isamu

    1999-07-01

    The preparation of amorphous silicon films and solar cells using SiH{sub 2}Cl{sub 2} source gas and electron cyclotron resonance assisted chemical vapor deposition (ECR-CVD) was investigated. By using buffer layers to protect previously deposited layers improved a-Si:H(Cl) solar cells were prepared and studied. The high quality a-Si:H(Cl) films used in this study exhibited low defect densities ({approximately}10{sup 15} cm{sup {minus}3}) and high stability under illumination even when the deposition rate was increased to {approximately} 15A/s. The solar cells were deposited in the n-i-p sequence. These solar cells achieved V{sub oc} values of {approximately}0.89V and {approximately}3.9% efficiency on Ga doped ZnO (GZO) coated specular substrate. The a-Si:H(Cl) electron and hole {mu}{tau} products were {approximately}10{sup {minus}8} cm{sup 2}/V.

  3. Direct Evidence of Phosphorus-Defect Complexes in n -Type Amorphous Silicon and Hydrogenated Amorphous Silicon

    SciTech Connect (OSTI)

    Petkov, M.P.; Weber, M.H.; Lynn, K.G.; Crandall, R.S.; Ghosh, V.J.

    1999-05-01

    We use positron annihilation spectroscopy (PAS) to identify the phosphorus-defect complex ({sup {asterisk}}D{sup {minus}}) in n -type hydrogenated amorphous Si (a -Si:H). The positrons are attracted and localized at the small open volume associated with the dangling bond defects. The radiation detected after annihilation gives a characteristic P signature, regarded as a {sup {asterisk}}D{sup {minus}} {open_quotes}fingerprint.{close_quotes} Additional evidence is obtained from a comparison to P-implanted amorphized Si, as well as from theoretical calculations. This work lays the foundation for PAS studies of impurity-defect related processes in a -Si:H. {copyright} {ital 1999} {ital The American Physical Society}

  4. Stable, high-efficiency amorphous silicon solar cells with low hydrogen content

    SciTech Connect (OSTI)

    Fortmann, C.M.; Hegedus, S.S. )

    1992-12-01

    Results and conclusions obtained during a research program of the investigation of amorphous silicon and amorphous silicon based alloy materials and solar cells fabricated by photo-chemical vapor and glow discharge depositions are reported. Investigation of the effects of the hydrogen content in a-si:H i-layers in amorphous silicon solar cells show that cells with lowered hydrogen content i-layers are more stable. A classical thermodynamic formulation of the Staebler-Wronski effect has been developed for standard solar cell operating temperatures and illuminations. Methods have been developed to extract a lumped equivalent circuit from the current voltage characteristic of a single junction solar cell in order to predict its behavior in a multijunction device.

  5. Method for improving the stability of amorphous silicon

    DOE Patents [OSTI]

    Branz, Howard M.

    2004-03-30

    A method of producing a metastable degradation resistant amorphous hydrogenated silicon film is provided, which comprises the steps of growing a hydrogenated amorphous silicon film, the film having an exposed surface, illuminating the surface using an essentially blue or ultraviolet light to form high densities of a light induced defect near the surface, and etching the surface to remove the defect.

  6. Superlattice doped layers for amorphous silicon photovoltaic cells

    DOE Patents [OSTI]

    Arya, Rajeewa R.

    1988-01-12

    Superlattice doped layers for amorphous silicon photovoltaic cells comprise a plurality of first and second lattices of amorphous silicon alternatingly formed on one another. Each of the first lattices has a first optical bandgap and each of the second lattices has a second optical bandgap different from the first optical bandgap. A method of fabricating the superlattice doped layers also is disclosed.

  7. Hydrogen plasma treatments for passivation of amorphous-crystalline silicon-heterojunctions on surfaces promoting epitaxy

    SciTech Connect (OSTI)

    Mews, Mathias; Mingirulli, Nicola; Korte, Lars; Schulze, Tim F.

    2013-03-25

    The impact of post-deposition hydrogen plasma treatment (HPT) on passivation in amorphous/crystalline silicon (a-Si:H/c-Si) interfaces is investigated. Combining low temperature a-Si:H deposition and successive HPT, a high minority carrier lifetime >8 ms is achieved on c-Si <100>, which is otherwise prone to epitaxial growth and thus inferior passivation. It is shown that the passivation improvement stems from diffusion of hydrogen atoms to the heterointerface and subsequent dangling bond passivation. Concomitantly, the a-Si:H hydrogen density increases, leading to band gap widening and void formation, while the film disorder is not increased. Thus, HPT allows for a-Si:H band gap and a-Si:H/c-Si band offset engineering.

  8. Amorphous silicon carbide passivating layers for crystalline-silicon-based heterojunction solar cells

    SciTech Connect (OSTI)

    Boccard, Mathieu; Holman, Zachary C.

    2015-08-14

    With this study, amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, amorphous silicon carbide being shown to surpass amorphous silicon for temperatures above 300C. We demonstrate open-circuit voltage values over 700 mV for complete cells, and an improved temperature stability for the open-circuit voltage. Transport of electrons and holes across the hetero-interface is studied with complete cells having amorphous silicon carbide either on the hole-extracting side or on the electron-extracting side, and a better transport of holes than of electrons is shown. Also, due to slightly improved transparency, complete solar cells using an amorphous silicon carbide passivation layer on the hole-collecting side are demonstrated to show slightly better performances even prior to annealing than obtained with a standard amorphous silicon layer.

  9. Amorphous silicon carbide passivating layers for crystalline-silicon-based heterojunction solar cells

    SciTech Connect (OSTI)

    Boccard, Mathieu; Holman, Zachary C.

    2015-08-14

    With this study, amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, amorphous silicon carbide being shown to surpass amorphous silicon for temperatures above 300°C. We demonstrate open-circuit voltage values over 700 mV for complete cells, and an improved temperature stability for the open-circuit voltage. Transport of electrons and holes across the hetero-interface is studied with complete cells having amorphous silicon carbide either on the hole-extracting side or on the electron-extracting side, and a better transport of holes than of electrons is shown. Also, due to slightly improved transparency, complete solar cells using an amorphous silicon carbide passivation layer on the hole-collecting side are demonstrated to show slightly better performances even prior to annealing than obtained with a standard amorphous silicon layer.

  10. Amorphous silicon materials and solar cells

    SciTech Connect (OSTI)

    Stafford, B.L. )

    1991-01-01

    An International Meeting on Stability of Amorphous Silicon Materials and Solar Cells was held in Denver, CO on February 20--22, 1991. The main objectives of the meeting were to bring to light-and stimulate discussion on-recent advances in (1) understanding the underlying mechanisms of light-induced instability and (2) engineering approaches to stable solar cells. Several of the experimental and theoretical papers presented here, particularly those regarding low-hydrogen-content materials, give cause for optimism that the performance may finally be yielding to worldwide concerted efforts to understand and mitigate it. The four main topics discussed are modeling metastability, experimental data and model verification, materials studies, and solar cell studies.

  11. Highly efficient ultrathin-film amorphous silicon solar cells on top of imprinted periodic nanodot arrays

    SciTech Connect (OSTI)

    Yan, Wensheng Gu, Min; Tao, Zhikuo; Ong, Thiam Min Brian

    2015-03-02

    The addressing of the light absorption and conversion efficiency is critical to the ultrathin-film hydrogenated amorphous silicon (a-Si:H) solar cells. We systematically investigate ultrathin a-Si:H solar cells with a 100 nm absorber on top of imprinted hexagonal nanodot arrays. Experimental evidences are demonstrated for not only notable silver nanodot arrays but also lower-cost ITO and Al:ZnO nanodot arrays. The measured external quantum efficiency is explained by the simulation results. The J{sub sc} values are 12.1, 13.0, and 14.3 mA/cm{sup 2} and efficiencies are 6.6%, 7.5%, and 8.3% for ITO, Al:ZnO, and silver nanodot arrays, respectively. Simulated optical absorption distribution shows high light trapping within amorphous silicon layer.

  12. RF Sputtering for preparing substantially pure amorphous silicon monohydride

    DOE Patents [OSTI]

    Jeffrey, Frank R.; Shanks, Howard R.

    1982-10-12

    A process for controlling the dihydride and monohydride bond densities in hydrogenated amorphous silicon produced by reactive rf sputtering of an amorphous silicon target. There is provided a chamber with an amorphous silicon target and a substrate therein with the substrate and the target positioned such that when rf power is applied to the target the substrate is in contact with the sputtering plasma produced thereby. Hydrogen and argon are fed to the chamber and the pressure is reduced in the chamber to a value sufficient to maintain a sputtering plasma therein, and then rf power is applied to the silicon target to provide a power density in the range of from about 7 watts per square inch to about 22 watts per square inch to sputter an amorphous silicon hydride onto the substrate, the dihydride bond density decreasing with an increase in the rf power density. Substantially pure monohydride films may be produced.

  13. Amorphous silicon carbide passivating layers for crystalline-silicon-based heterojunction solar cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Boccard, Mathieu; Holman, Zachary C.

    2015-08-14

    With this study, amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, amorphousmore » silicon carbide being shown to surpass amorphous silicon for temperatures above 300°C. We demonstrate open-circuit voltage values over 700 mV for complete cells, and an improved temperature stability for the open-circuit voltage. Transport of electrons and holes across the hetero-interface is studied with complete cells having amorphous silicon carbide either on the hole-extracting side or on the electron-extracting side, and a better transport of holes than of electrons is shown. Also, due to slightly improved transparency, complete solar cells using an amorphous silicon carbide passivation layer on the hole-collecting side are demonstrated to show slightly better performances even prior to annealing than obtained with a standard amorphous silicon layer.« less

  14. Process for producing amorphous and crystalline silicon nitride

    DOE Patents [OSTI]

    Morgan, P.E.D.; Pugar, E.A.

    1985-11-12

    A process for producing amorphous or crystalline silicon nitride is disclosed which comprises reacting silicon disulfide ammonia gas at elevated temperature. In a preferred embodiment silicon disulfide in the form of whiskers'' or needles is heated at temperature ranging from about 900 C to about 1,200 C to produce silicon nitride which retains the whisker or needle morphological characteristics of the silicon disulfide. Silicon carbide, e.g. in the form of whiskers, also can be prepared by reacting substituted ammonia, e.g. methylamine, or a hydrocarbon containing active hydrogen-containing groups, such as ethylene, with silicon disulfide, at elevated temperature, e.g. 900 C. 6 figs.

  15. Process for producing amorphous and crystalline silicon nitride

    DOE Patents [OSTI]

    Morgan, Peter E. D.; Pugar, Eloise A.

    1985-01-01

    A process for producing amorphous or crystalline silicon nitride is disclosed which comprises reacting silicon disulfide ammonia gas at elevated temperature. In a preferred embodiment silicon disulfide in the form of "whiskers" or needles is heated at temperature ranging from about 900.degree. C. to about 1200.degree. C. to produce silicon nitride which retains the whisker or needle morphological characteristics of the silicon disulfide. Silicon carbide, e.g. in the form of whiskers, also can be prepared by reacting substituted ammonia, e.g. methylamine, or a hydrocarbon containing active hydrogen-containing groups, such as ethylene, with silicon disulfide, at elevated temperature, e.g. 900.degree. C.

  16. In situ spectroscopic study of the plastic deformation of amorphous silicon under nonhydrostatic conditions induced by indentation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gerbig, Yvonne B.; Michaels, C. A.; Bradby, Jodie E.; Haberl, Bianca; Cook, Robert F.

    2015-12-17

    Indentation-induced plastic deformation of amorphous silicon (a-Si) thin films was studied by in situ Raman imaging of the deformed contact region of an indented sample, employing a Raman spectroscopy-enhanced instrumented indentation technique (IIT). The occurrence and evolving spatial distribution of changes in the a-Si structure caused by processes, such as polyamorphization and crystallization, induced by indentation loading were observed. Furthermore, the obtained experimental results are linked with previously published work on the plastic deformation of a-Si under hydrostatic compression and shear deformation to establish a model for the deformation behavior of a-Si under indentation loading.

  17. Charging/discharging behavior and mechanism of silicon quantum dots embedded in amorphous silicon carbide films

    SciTech Connect (OSTI)

    Wen, Xixing; Zeng, Xiangbin Zheng, Wenjun; Liao, Wugang; Feng, Feng

    2015-01-14

    The charging/discharging behavior of Si quantum dots (QDs) embedded in amorphous silicon carbide (a-SiC{sub x}) was investigated based on the Al/insulating layer/Si QDs embedded in a-SiC{sub x}/SiO{sub 2}/p-Si (metal-insulator-quantum dots-oxide-silicon) multilayer structure by capacitance-voltage (C-V) and conductance-voltage (G-V) measurements. Transmission electron microscopy and Raman scattering spectroscopy measurements reveal the microstructure and distribution of Si QDs. The occurrence and shift of conductance peaks indicate the carrier transfer and the charging/discharging behavior of Si QDs. The multilayer structure shows a large memory window of 5.2 eV at ±8 V sweeping voltage. Analysis of the C-V and G-V results allows a quantification of the Coulomb charging energy and the trapped charge density associated with the charging/discharging behavior. It is found that the memory window is related to the size effect, and Si QDs with large size or low Coulomb charging energy can trap two or more electrons by changing the charging voltage. Meanwhile, the estimated lower potential barrier height between Si QD and a-SiC{sub x}, and the lower Coulomb charging energy of Si QDs could enhance the charging and discharging effect of Si QDs and lead to an enlarged memory window. Further studies of the charging/discharging mechanism of Si QDs embedded in a-SiC{sub x} can promote the application of Si QDs in low-power consumption semiconductor memory devices.

  18. Well-Passivated a-Si:H Back Contacts for Double-Heterojunction Silicon Solar Cells: Preprint

    SciTech Connect (OSTI)

    Page, M. R.; Iwaniczko, E.; Xu, Y.; Wang, Q.; Yan, Y.; Roybal, L.; Branz, H. M.; Wang, T. H.

    2006-05-01

    We have developed hydrogenated amorphous silicon (a Si:H) back contacts to both p- and n-type silicon wafers, and employed them in double-heterojunction solar cells. These contacts are deposited entirely at low temperature (<250 C) and replace the standard diffused or alloyed back-surface-field contacts used in single-heterojunction (front-emitter only) cells. High-quality back contacts require excellent surface passivation, indicated by a low surface recombination velocity of minority-carriers (S) or a high open-circuit voltage (Voc). The back contact must also provide good conduction for majority carriers to the external circuit, as indicated by a high light I-V fill factor. We use hot-wire chemical vapor deposition (HWCVD) to grow a-Si:H layers for both the front emitters and back contacts. Our improved a-Si:H back contacts contribute to our recent achievement of a confirmed 18.2% efficiency in double-heterojunction silicon solar cells on p type textured silicon wafers.

  19. Percolation network in resistive switching devices with the structure of silver/amorphous silicon/p-type silicon

    SciTech Connect (OSTI)

    Liu, Yanhong; Gao, Ping; Bi, Kaifeng; Peng, Wei [School of Physics and Optoelectronic Engineering, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian 116024 (China); Jiang, Xuening; Xu, Hongxia [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian116024 (China)

    2014-01-27

    Conducting pathway of percolation network was identified in resistive switching devices (RSDs) with the structure of silver/amorphous silicon/p-type silicon (Ag/a-Si/p-Si) based on its gradual RESET-process and the stochastic complex impedance spectroscopy characteristics (CIS). The formation of the percolation network is attributed to amounts of nanocrystalline Si particles as well as defect sites embedded in a-Si layer, in which the defect sites supply positions for Ag ions to nucleate and grow. The similar percolation network has been only observed in Ag-Ge-Se based RSD before. This report provides a better understanding for electric properties of RSD based on the percolation network.

  20. Project Summary of the NREL Amorphous Silicon Team

    SciTech Connect (OSTI)

    Nelson, B. P.; Branz, H. M.; Crandall, R. S.; Iwaniczko, E.; Mahan, A. H.; Stradins, P.; Wang, Q.; Xu, Y.

    2003-05-01

    The Amorphous Silicon Team at NREL has improved the properties of many materials, increased solar cell device performance, and improved the fundamental understanding of thin-film silicon based materials and devices since the last NCPV Program Review Meeting. In this paper we present a summary of the work of the team since that last meeting.

  1. Comparative Study of Low-temperature PECVD of Amorphous Silicon using Mono-, Di-, Trisilane and Cyclohexasilane

    SciTech Connect (OSTI)

    Konstantin Pokhodnya; Joseph Sandstrom; Xuliang Dai; Philip Boudjouk; Douglas L. Schulz

    2009-06-08

    The hydrogenated amorphous silicon a-Si:H films were grown by plasma-enhanced chemical vapor deposition (PECVD) using liquid cyclohexasilane Si{sub 6}H{sub 12} (CHS). The growth rate of a-Si:H was studied as a function of substrate temperatures in the range of 30 C < T < 450 C using deposition conditions that were optimized for monosilane SiH{sub 4}. The same parameters were used for a-Si:H films grown using disilane (Si{sub 2}H{sub 6}) and trisilane (Si{sub 3}H{sub 8}) precursors. It was found that the a-Si:H film growth rate for CHS is lower with respect to those for mono-, di- and trisilane in an Ar plasma. Addition of {approx}10% of H{sub 2} dramatically increases the deposition rate for CHS-based films to {_}nm/min - a 700% increase. The as-deposited films were characterized by FTIR and Raman spectroscopy to probe the hydrogen content and local bonding environment. It was found that the films grown using Ar/H{sub 2} mixtures as carrier gas have a reduced hydrogen content relative to polysilane fragments indicating higher quality amorphous silicon.

  2. Hot wire deposited hydrogenated amorphous silicon solar cells

    SciTech Connect (OSTI)

    Mahan, A.H.; Iwaniczko, E.; Nelson, B.P.; Reedy, R.C., Jr.; Unold, T.; Crandall, R.S.; Guha, S.; Yang, J. |

    1997-02-01

    This paper details the results of a study in which low H content, high deposition rate hot wire (HW) deposited amorphous silicon (a-Si:H) has been incorporated into a substrate solar cell. We find that the treatment of the top surface of the HW i-layer while it is cooled from its high deposition temperature is crucial to device performance. We present data concerning these surface treatments, and correlate these treatments with Schottky device performance. We also present first generation HW n-i-p solar cell data, where a glow discharge (GD) {mu}c-Si(p) layer completes the partial devices. No light trapping layer is used to increase the device Jsc. Our preliminary results yield efficiencies of up to 6.8{percent} for a cell with a 4000 {Angstrom} thick HW i-layer, which degrade less than 10{percent} after a 900h AM1 light soak. We suggest areas for further improvement of our devices. {copyright} {ital 1997 American Institute of Physics.}

  3. Hot wire deposited hydrogenated amorphous silicon solar cells

    SciTech Connect (OSTI)

    Mahan, A.H.; Iwaniczko, E.; Nelson, B.P.; Reedy, R.C. Jr.; Crandall, R.S.; Guha, S.; Yang, J.

    1996-09-01

    This paper details the results of a study in which low H content, high deposition rate hot wire (HW) deposited amorphous silicon (a-Si:H) has been incorporated into a substrate solar cell. The authors find that the treatment of the top surface of the HW i layer while it is being cooled from its high deposition temperature is crucial to device performance. They present data concerning these surface treatments, and they correlate these treatments with Schottky device performance. They also present first generation HW n-i-p solar cell efficiency data, where a glow discharge (GD) {mu}c-Si(p) layer was added to complete the partial devices. No light trapping layer was used to increase the device Jsc. The preliminary investigations have yielded efficiencies of up to 6.8% for a cell with a 4,000 {angstrom} thick HW i-layer, which degrade less than 10% after a 900 hour light soak. They suggest avenues for further improvement of the devices.

  4. Hot wire deposited hydrogenated amorphous silicon solar cells

    SciTech Connect (OSTI)

    Mahan, A.H.; Iwaniczko, E.; Nelson, B.P.; Reedy, R.C. Jr.; Crandall, R.S.

    1996-05-01

    This paper details the results of a study in which low H content, high deposition rate hot wire (HW) deposited amorphous silicon (a-Si:H) has been incorporated into a substrate solar cell. The authors find that the treatment of the top surface of the HW i layer while it is being cooled from its high deposition temperature is crucial to device performance. They present data concerning these surface treatments, and correlate these treatments with Schottky device performance. The authors also present first generation HW n-i-p solar cell efficiency data, where a glow discharge (GD) {mu}c-Si(p) layer was added to complete the partial devices. No light trapping layer was used to increase the device Jsc. Their preliminary investigations have yielded efficiencies of up to 6.8% for a cell with a 4000 {Angstrom} thick HW i-layer, which degrade less than 10% after a 900 hour light soak. The authors suggest avenues for further improvement of their devices.

  5. Outdoor performance stability and controlled light-soak testing of amorphous silicon multijunction modules at NREL

    SciTech Connect (OSTI)

    Mrig, L.; Burdick, J.; Luft, W.; Kroposki, B.

    1994-12-31

    The National Renewable Energy Laboratory (NREL) has been testing amorphous silicon (a-Si) Photovoltaic (PV) modules for more than a decade. NREL has been conducting controlled light-soak testing of multijunction a-Si modules to characterize their performance for stability evaluation as well as to benchmark the technology status. Some of the test modules, after controlled light-soak testing, have been installed outdoors. The authors have observed that under outdoor exposure, the modules further degrade in performance, possibly due to lower outdoor temperatures and varying spectra. The paper presents data on the light-induced degradation for the third controlled light-soak test on multijunction a-Si modules as well as outdoor performance data on single- and multijunction modules under prevailing conditions.

  6. Outdoor performance stability and controlled light-soak testing of amorphous silicon multijunction modules at NREL

    SciTech Connect (OSTI)

    Mrig, L.; Burdick, J.; Luft, W.; Kroposki, B.

    1995-10-01

    The National Renewable Energy Laboratory (NREL) has been testing amorphous silicon (a-Si) Photovoltaic (PV) modules for more than a decade. NREL has been conducting controlled light-soak testing of multifunction a-Si modules to characterize their performance for stability evaluation as well as to benchmark the technology status. Some of the test modules, after controlled light-soak testing, have been installed outdoors. The authors have observed that under outdoor exposure, the modules further degrade in performance, possibly due to lower outdoor temperatures and varying spectra. The paper presents data on the light-induced degradation for the third controlled light-soak test on multijunction a-Si modules as well as outdoor performance data on single and multijunction modules under prevailing conditions.

  7. Transmissive metallic contact for amorphous silicon solar cells

    DOE Patents [OSTI]

    Madan, A.

    1984-11-29

    A transmissive metallic contact for amorphous silicon semiconductors includes a thin layer of metal, such as aluminum or other low work function metal, coated on the amorphous silicon with an antireflective layer coated on the metal. A transparent substrate, such as glass, is positioned on the light reflective layer. The metallic layer is preferably thin enough to transmit at least 50% of light incident thereon, yet thick enough to conduct electricity. The antireflection layer is preferably a transparent material that has a refractive index in the range of 1.8 to 2.2 and is approximately 550A to 600A thick.

  8. Solution-processed amorphous silicon surface passivation layers

    SciTech Connect (OSTI)

    Mews, Mathias Sontheimer, Tobias; Korte, Lars; Rech, Bernd; Mader, Christoph; Traut, Stephan; Wunnicke, Odo

    2014-09-22

    Amorphous silicon thin films, fabricated by thermal conversion of neopentasilane, were used to passivate crystalline silicon surfaces. The conversion is investigated using X-ray and constant-final-state-yield photoelectron spectroscopy, and minority charge carrier lifetime spectroscopy. Liquid processed amorphous silicon exhibits high Urbach energies from 90 to 120?meV and 200?meV lower optical band gaps than material prepared by plasma enhanced chemical vapor deposition. Applying a hydrogen plasma treatment, a minority charge carrier lifetime of 1.37?ms at an injection level of 10{sup 15}/cm{sup 3} enabling an implied open circuit voltage of 724?mV was achieved, demonstrating excellent silicon surface passivation.

  9. Laterally inherently thin amorphous-crystalline silicon heterojunction photovoltaic cell

    SciTech Connect (OSTI)

    Chowdhury, Zahidur R. Kherani, Nazir P.

    2014-12-29

    This article reports on an amorphous-crystalline silicon heterojunction photovoltaic cell concept wherein the heterojunction regions are laterally narrow and distributed amidst a backdrop of well-passivated crystalline silicon surface. The localized amorphous-crystalline silicon heterojunctions consisting of the laterally thin emitter and back-surface field regions are precisely aligned under the metal grid-lines and bus-bars while the remaining crystalline silicon surface is passivated using the recently proposed facile grown native oxide–plasma enhanced chemical vapour deposited silicon nitride passivation scheme. The proposed cell concept mitigates parasitic optical absorption losses by relegating amorphous silicon to beneath the shadowed metallized regions and by using optically transparent passivation layer. A photovoltaic conversion efficiency of 13.6% is obtained for an untextured proof-of-concept cell illuminated under AM 1.5 global spectrum; the specific cell performance parameters are V{sub OC} of 666 mV, J{sub SC} of 29.5 mA-cm{sup −2}, and fill-factor of 69.3%. Reduced parasitic absorption, predominantly in the shorter wavelength range, is confirmed with external quantum efficiency measurement.

  10. Self-bias voltage diagnostics for the amorphous-to-microcrystalline transition in a-Si:H under a hydrogen-plasma treatment

    SciTech Connect (OSTI)

    Hadjadj, A.; Pham, N.; Roca i Cabarrocas, P.; Jbara, O.

    2010-03-15

    The authors demonstrate the possibility of using self-bias voltage on the radio-frequency electrode of a capacitively coupled deposition system as a diagnostic tool to detect the amorphous-to-microcrystalline silicon transition during the exposure of a-Si:H thin films to a hydrogen plasma. This is achieved by combining self-bias voltage (V{sub dc}) and kinetic-ellipsometry measurements, which provide real-time information on the film properties. On intrinsic and n-type a-Si:H films, the hydrogen-plasma exposure results in the formation of a hydrogen-modified layer, which is accompanied with a decrease in the absolute values of V{sub dc}, until a plateau corresponding to the nucleation and the growth of the microcrystalline layer occurs. On p-type a-Si:H, the amorphous-to-microcrystalline transition is characterized by a rapid increase in the absolute values of V{sub dc}. This particular trend is ascribed to the effects of boron on both the solid and plasma phases.

  11. High-Efficiency Amorphous Silicon Alloy Based Solar Cells and Modules; Final Technical Progress Report, 30 May 2002--31 May 2005

    SciTech Connect (OSTI)

    Guha, S.; Yang, J.

    2005-10-01

    The principal objective of this R&D program is to expand, enhance, and accelerate knowledge and capabilities for development of high-efficiency hydrogenated amorphous silicon (a-Si:H) and amorphous silicon-germanium alloy (a-SiGe:H) related thin-film multijunction solar cells and modules with low manufacturing cost and high reliability. Our strategy has been to use the spectrum-splitting triple-junction structure, a-Si:H/a-SiGe:H/a-SiGe:H, to improve solar cell and module efficiency, stability, and throughput of production. The methodology used to achieve the objectives included: (1) explore the highest stable efficiency using the triple-junction structure deposited using RF glow discharge at a low rate, (2) fabricate the devices at a high deposition rate for high throughput and low cost, and (3) develop an optimized recipe using the R&D batch large-area reactor to help the design and optimization of the roll-to-roll production machines. For short-term goals, we have worked on the improvement of a-Si:H and a-SiGe:H alloy solar cells. a-Si:H and a-SiGe:H are the foundation of current a-Si:H based thin-film photovoltaic technology. Any improvement in cell efficiency, throughput, and cost reduction will immediately improve operation efficiency of our manufacturing plant, allowing us to further expand our production capacity.

  12. Anisotropy in hydrogenated amorphous silicon films as observed using polarized FTIR-ATR spectroscopy

    SciTech Connect (OSTI)

    Webb, J.D.; Gedvilas, L.M.; Crandall, R.S.; Iwaniczko, E.; Nelson, B.P.; Mahan, A.H.; Reedy, R.; Matson, R.J.

    1999-07-01

    The authors used polarized attenuated total reflection (ATR) measurements together with Fourier transform infrared (FTIR) spectroscopy to investigate the vibrational spectra of hydrogenated amorphous silicon (a-SiH{sub x}) films 0.5--1.0 microns in thickness. They deposited the films using hot-wire or plasma-enhanced chemical vapor deposition methods (HWCVD or PECVD, respectively) on crystalline silicon and cadmium telluride substrates. The ATR technique gave a spectral range from 2,100--400 cm{sup {minus}1}, although the Si-H wagging mode absorption band at 640 cm{sup {minus}1} was somewhat distorted in the a-SiH{sub x}/Si samples by impurity and lattice absorption in the silicon ATR substrates. They report the identification of a Si-O-C impurity band with maximum intensity at 1,240--1,230 cm{sup {minus}1}. The assignment of this band to a Si-O-C vibration is supported by secondary-ion mass spectrometry (SIMS) measurements. The polarized FTIR-ATR spectra of HWCVD and PECVD a-SiH{sub x} films on <111> Si ATR substrates show that the impurity dipoles are oriented strongly parallel to the film growth direction. The wagging mode absorbance band is more intense in the film plane. This trend is less pronounced for the Si-H stretching vibrations. These observations are consistent with some degree of anisotropy or medium-range order in the films. The anisotropy in the Si-H bands may be related to residual stress in the films. The scanning electron microscopy (SEM) analyses of the samples offer additional evidence of bulk structural anisotropy in the a-SiH{sub x}/Si films. However, the Si-O-C impurity band was not observed in the polarized ATR-FTIR spectra of the a-SiH{sub x}/CdTe samples, thus indicating that the Si substrates influence formation of the impurity in the a-SiH{sub x}/Si films.

  13. Anisotropy in Hydrogenated Amorphous Silicon Films as Observed Using Polarized FTIR-ATR Spectroscopy

    SciTech Connect (OSTI)

    Webb, J. D.; Gedvilas, L. M.; Crandall, R. S.; Iwaniczko, E.; Nelson, B. P.; Mahan, A. H.; Reedy, R.; Matson, R. J.

    1999-05-14

    We used polarized attenuated total reflection (ATR) measurements together with Fourier transform infrared (FTIR) spectroscopy to investigate the vibrational spectra of hydrogenated amorphous silicon (a-SiH{sub x}) films 0.5-1.0 microns in thickness. We deposited the films using hot-wire or plasma-enhanced chemical vapor deposition methods (HWCVD or PECVD, respectively) on crystalline silicon and cadmium telluride substrates. Our ATR technique gave a spectral range from 2100-400 cm{sup -1}, although the Si-H wagging mode absorption band at 640 cm{sup -1} was somewhat distorted in the a-SiHx/Si samples by impurity and lattice absorption in the silicon ATR substrates. We report the identification of a Si-O-C impurity band with maximum intensity at 1240-1230 cm{sup -1}. The assignment of this band to a Si-O-C vibration is supported by secondary-ion mass spectrometry (SIMS) measurements. Our polarized FTIR-ATR spectra of HWCVD and PECVD a-SiH{sub x} films on <111> Si ATR substrates show that the impurity dipoles ar e oriented strongly parallel to the film growth direction. The wagging mode absorbance band is more intense in the film plane. This trend is less pronounced for the Si-H stretching vibrations. These observations are consistent with some degree of anisotropy or medium-range order in the films. The anisotropy in the Si-H bands may be related to residual stress in the films. Our scanning electron microscopy (SEM) analyses of the samples offer additional evidence of bulk structural anisotropy in the a-SiH{sub x}/Si films. However, the Si-O-C impurity band was not observed in the polarized ATR-FTIR spectra of the a-SiH{sub x}/CdTe samples, thus indicating that the Si substrates influence formation of the impurity in the a-SiH{sub x}/Si films.

  14. High Thermal Conductivity of a Hydrogenated Amorphous Silicon Film

    SciTech Connect (OSTI)

    Liu, X.; Feldman, J. L.; Cahill, D. G.; Crandall, R. S.; Bernstein, N.; Photiadis, D. M.; Mehl, M. J.; Papaconstantopoulos, D. A.

    2009-01-23

    We measured the thermal conductivity {kappa} of an 80 {micro}m thick hydrogenated amorphous silicon film prepared by hot-wire chemical-vapor deposition with the 3{omega} (80-300 K) and the time-domain thermoreflectance (300 K) methods. The {kappa} is higher than any of the previous temperature dependent measurements and shows a strong phonon mean free path dependence. We also applied a Kubo based theory using a tight-binding method on three 1000 atom continuous random network models. The theory gives higher {kappa} for more ordered models, but not high enough to explain our results, even after extrapolating to lower frequencies with a Boltzmann approach. Our results show that this material is more ordered than any amorphous silicon previously studied.

  15. Deposition of device quality, low hydrogen content, amorphous silicon films by hot filament technique using "safe" silicon source gas

    DOE Patents [OSTI]

    Mahan, Archie Harvin; Molenbroek, Edith C.; Nelson, Brent P.

    1998-01-01

    A method of producing hydrogenated amorphous silicon on a substrate by flowing a stream of safe (diluted to less than 1%) silane gas past a heated filament.

  16. Effective interface state effects in hydrogenated amorphous-crystalline silicon heterostructures using ultraviolet laser photocarrier radiometry

    SciTech Connect (OSTI)

    Melnikov, A.; Mandelis, A.; Halliop, B.; Kherani, N. P.

    2013-12-28

    Ultraviolet photocarrier radiometry (UV-PCR) was used for the characterization of thin-film (nanolayer) intrinsic hydrogenated amorphous silicon (i-a-Si:H) on c-Si. The small absorption depth (approximately 10?nm at 355?nm laser excitation) leads to strong influence of the nanolayer parameters on the propagation and recombination of the photocarrier density wave (CDW) within the layer and the substrate. A theoretical PCR model including the presence of effective interface carrier traps was developed and used to evaluate the transport parameters of the substrate c-Si as well as those of the i-a-Si:H nanolayer. Unlike conventional optoelectronic characterization methods such as photoconductance, photovoltage, and photoluminescence, UV-PCR can be applied to more complete quantitative characterization of a-Si:H/c-Si heterojunction solar cells, including transport properties and defect structures. The quantitative results elucidate the strong effect of a front-surface passivating nanolayer on the transport properties of the entire structure as the result of effective a-Si:H/c-Si interface trap neutralization through occupation. A further dramatic improvement of those properties with the addition of a back-surface passivating nanolayer is observed and interpreted as the result of the interaction of the increased excess bulk CDW with, and more complete occupation and neutralization of, effective front interface traps.

  17. TEM observations of hydrogen nanobubbles in implanted amorphous silicon

    SciTech Connect (OSTI)

    Jones, K.M.; Al-Jassim, M.M.; Williamson, D.L.; Acco, S.

    1996-12-31

    Over the last two decades extensive studies on the optical and electrical properties of hydrogenated amorphous Si (a-Si:H) have been reported. However, less attention was given to the structural characterization of this material partly due to the insensitivity to hydrogen of structural probes such as x-rays and electron diffraction. From a recent set of experiments, results on the solubility limit of hydrogen in a special type of a-Si:H and the characterization of hydrogen induced complexes or nanobubbles has been reported. In this study, we report TEM observations of the structural morphology of hydrogen related defects that support these recent measurements obtained by secondary ion mass spectrometry (SIMS) and small-angle x-ray scattering (SAXS).

  18. Electron-beam-induced information storage in hydrogenated amorphous silicon devices

    DOE Patents [OSTI]

    Yacobi, B.G.

    1985-03-18

    A method for recording and storing information in a hydrogenated amorphous silicon device, comprising: depositing hydrogenated amorphous silicon on a substrate to form a charge collection device; and generating defects in the hydrogenated amorphous silicon device, wherein the defects act as recombination centers that reduce the lifetime of carriers, thereby reducing charge collection efficiency and thus in the charge collection mode of scanning probe instruments, regions of the hydrogenated amorphous silicon device that contain the defects appear darker in comparison to regions of the device that do not contain the defects, leading to a contrast formation for pattern recognition and information storage.

  19. Improved method of preparing p-i-n junctions in amorphous silicon semiconductors

    DOE Patents [OSTI]

    Madan, A.

    1984-12-10

    A method of preparing p/sup +/-i-n/sup +/ junctions for amorphous silicon semiconductors includes depositing amorphous silicon on a thin layer of trivalent material, such as aluminum, indium, or gallium at a temperature in the range of 200/sup 0/C to 250/sup 0/C. At this temperature, the layer of trivalent material diffuses into the amorphous silicon to form a graded p/sup +/-i junction. A layer of n-type doped material is then deposited onto the intrinsic amorphous silicon layer in a conventional manner to finish forming the p/sup +/-i-n/sup +/ junction.

  20. High Efficiency Triple-Junction Amorphous Silicon Alloy Photovoltaic Technology, Final Technical Report, 6 March 1998 - 15 October 2001

    SciTech Connect (OSTI)

    Guha, S.

    2001-11-08

    This report describes the research program intended to expand, enhance, and accelerate knowledge and capabilities for developing high-performance, two-terminal multijunction amorphous silicon (a-Si) alloy cells, and modules with low manufacturing cost and high reliability. United Solar uses a spectrum-splitting, triple-junction cell structure. The top cell uses an amorphous silicon alloy of {approx}1.8-eV bandgap to absorb blue photons. The middle cell uses an amorphous silicon germanium alloy ({approx}20% germanium) of {approx}1.6-eV bandgap to capture green photons. The bottom cell has {approx}40% germanium to reduce the bandgap to {approx}1.4-eV to capture red photons. The cells are deposited on a stainless-steel substrate with a predeposited silver/zinc oxide back reflector to facilitate light-trapping. A thin layer of antireflection coating is applied to the top of the cell to reduce reflection loss. The major research activities conducted under this program were: (1) Fundamental studies to improve our understanding of materials and devices; the work included developing and analyzing a-Si alloy and a-SiGe alloy materials prepared near the threshold of amorphous-to-microcrystalline transition and studying solar cells fabricated using these materials. (2) Deposition of small-area cells using a radio-frequency technique to obtain higher deposition rates. (3) Deposition of small-area cells using a modified very high frequency technique to obtain higher deposition rates. (4) Large-area cell research to obtain the highest module efficiency. (5) Optimization of solar cells and modules fabricated using production parameters in a large-area reactor.

  1. Structural origin of bulk molecular hydrogen in hydrogenated amorphous silicon

    SciTech Connect (OSTI)

    Liu, X.; Pohl, R.O.; Crandall, R.S.

    1999-07-01

    The elastic anomaly observed previously at the triple point of bulk molecular hydrogen in hydrogenated amorphous silicon films prepared by hot-wire chemical-vapor deposition has also been observed in deuterated films at the triple point of D{sub 2}. The origin of this anomaly has now been traced to bubbles formed at the crystalline-amorphous interface. An upper limit of the pressure in these bubbles at their formation temperature, 440 C, has been estimated to be 11 MPa, and is suggested to be a measure of the bonding strength between film and substrate at that temperature. Bubble formation after heat treatment at 400 C has also been observed in films prepared by plasma-enhanced chemical-vapor deposition. The internal friction anomalies resemble those observed previously in cold-worked hydrogenated iron where they have been interpreted through plastic deformation of solid hydrogen in voids.

  2. Enhanced electrochemical etching of ion irradiated silicon by localized amorphization

    SciTech Connect (OSTI)

    Dang, Z. Y.; Breese, M. B. H.; Lin, Y.; Tok, E. S.; Vittone, E.

    2014-05-12

    A tailored distribution of ion induced defects in p-type silicon allows subsequent electrochemical anodization to be modified in various ways. Here we describe how a low level of lattice amorphization induced by ion irradiation influences anodization. First, it superposes a chemical etching effect, which is observable at high fluences as a reduced height of a micromachined component. Second, at lower fluences, it greatly enhances electrochemical anodization by allowing a hole diffusion current to flow to the exposed surface. We present an anodization model, which explains all observed effects produced by light ions such as helium and heavy ions such as cesium over a wide range of fluences and irradiation geometries.

  3. Cathodic deposition of amorphous alloys of silicon, carbon, and fluorine

    SciTech Connect (OSTI)

    Lee, C.H.; Kroger, F.A.

    1982-05-01

    Amorphous silicon containing fluorine and carbon, pure and doped with boron or phosphorus, was deposited cathodically from solutions of K/sub 2/SiF/sub 6/ in acetone with HF. The conditions for optimum deposition were determined, and the deposits were characterized by electron microprobe x-ray emission, electrical conductivity, and infrared absorption. Doping with phosphorus causes a change from p- to n-type semiconductor behavior, with a maximum of resistivity >10/sup 13/ /OMEGA/ cm at the compensation point. 48 refs.

  4. The long-term stability of amorphous silicon flat panel imaging devices for dosimetry purposes

    SciTech Connect (OSTI)

    Louwe, R.J.W.; McDermott, L.N.; Sonke, J.-J.; Tielenburg, R.; Wendling, M.; Herk, M.B. van; Mijnheer, B.J.

    2004-11-01

    This study was carried out to determine the stability of the response of amorphous silicon (a-Si)-flat panel imagers for dosimetry applications. Measurements of the imager's response under reference conditions were performed on a regular basis for four detectors of the same manufacturer. We found that the ambient temperature influenced the dark-field, while the gain of the imager signal was unaffected. Therefore, temperature fluctuations were corrected for by applying a 'dynamic' dark-field correction. This correction method also removed the influence of a small, irreversible increase of the dark-field current, which was equal to 0.5% of the dynamic range of the imager per year and was probably caused by mild radiation damage to the a-Si array. By applying a dynamic dark-field correction, excellent stability of the response over the entire panel of all imagers of 0.5% (1 SD) was obtained over an observation period up to 23 months. However, two imagers had to be replaced after several months. For one imager, an image segment stopped functioning, while the image quality of the other imager degraded significantly. We conclude that the tested a-Si EPIDs have a very stable response and are therefore well suited for dosimetry. We recommend, however, applying quality assurance tests dedicated to both imaging and dosimetry.

  5. The boron-tailing myth in hydrogenated amorphous silicon solar cells

    SciTech Connect (OSTI)

    Stuckelberger, M. Bugnon, G.; Despeisse, M.; Schüttauf, J.-W.; Haug, F.-J.; Ballif, C.; Park, B.-S.

    2015-11-16

    The boron-tailing effect in hydrogenated amorphous silicon (a-Si:H) solar cells describes the reduced charge collection specifically in the blue part of the spectrum for absorber layers deposited above a critical temperature. This effect limits the device performance of state-of-the art solar cells: For enhanced current density (reduced bandgap), the deposition temperature should be as high as possible, but boron tailing gets detrimental above 200 °C. To investigate this limitation and to show potential paths to overcome it, we deposited high-efficiency a-Si:H solar cells, varying the deposition temperatures of the p-type and the intrinsic absorber (i) layers between 150 and 250 °C. Using secondary ion mass spectroscopy, we study dedicated stacks of i-p-i layers deposited at different temperatures. This allows us to track boron diffusion at the p-i and i-p interfaces as they occur in the p-i-n and n-i-p configurations of a-Si:H solar cells for different deposition conditions. Finally, we prove step-by-step that the common explanation for boron tailing—boron diffusion from the p layer into the i layer leading to enhanced recombination—is not generally true and propose an alternative explanation for the experimentally observed drop in the external quantum efficiency at short wavelengths.

  6. Amorphous silicon research. Phase III technical progress report, August 1, 1996--July 31, 1997

    SciTech Connect (OSTI)

    Guha, S.

    1997-11-01

    The principal objective of this R&D program is to expand, enhance and accelerate knowledge and capabilities for the development of high-performance, two-terminal multijunction hydrogenated amorphous silicon (a-Si) alloy cells and modules. The near-term goal of the program is to achieve 12% stable active-area efficiency using the multijunction approach. The long-term goal is to achieve 15% stable efficiency multijunction modules. The major effort of this program is to develop high efficiency component cells and incorporate them in the triple-junction structure to obtain the highest stable efficiency. New and improved deposition regimes were investigated to obtain better cell performance. Fundamental studies to obtain better understanding of material and cell performance were undertaken.

  7. Research on stable, high-efficiency, large-area, amorphous-silicon-based submodules

    SciTech Connect (OSTI)

    Delahoy, A.E.; Tonon, T.; Macneil, J. (Chronar Corp., Princeton, NJ (USA))

    1991-06-01

    The primary objective of this subcontract is to develop the technology for same bandgap, amorphous silicon tandem junction photovoltaic modules having an area of at least 900 cm{sup 2} with the goal of achieving an aperture area efficiency of 9%. A further objective is to demonstrate modules that retain 95% of their under standard light soaking conditions. Our approach to the attainment of these objective is based on the following distinctive technologies: (a) in-house deposition of SiO{sub 2}/SnO{sub 2}:F onto soda lime glass by APCVD to provide a textured, transparent electrode, (b) single chamber r.f. flow discharge deposition of the a-Si:H layers onto vertical substrates contained with high package density in a box carrier'' to which the discharge is confined (c) sputter deposition of highly reflecting, ZnO-based back contacts, and (d) laser scribing of the a-Si:H and electrodes with real-time scribe tracking to minimize area loss. Continued development of single junction amorphous silicon was aggressively pursued as proving ground for various optical enhancement schemes, new p-layers, and i-layers quality. We have rigorously demonstrated that the introduction of a transitional i-layer does not impair stability and that the initial gain in performance is retained. We have demonstrated a small improvement in cell stability through a post-fabrication treatment consisting of multiple, intense light flashes followed by sufficient annealing. Finally, several experiments have indicated that long term stability can be improved by overcoating the SnO{sub 2} with ZnO. 25 refs., 17 figs.

  8. Sputtered pin amorphous silicon semi-conductor device and method therefor

    DOE Patents [OSTI]

    Moustakas, Theodore D.; Friedman, Robert A.

    1983-11-22

    A high efficiency amorphous silicon PIN semi-conductor device is constructed by the sequential sputtering of N, I and P layers of amorphous silicon and at least one semi-transparent ohmic electrode. A method of construction produces a PIN device, exhibiting enhanced physical integrity and facilitates ease of construction in a singular vacuum system and vacuum pump down procedure.

  9. Electron-beam-induced information storage in hydrogenated amorphous silicon device

    DOE Patents [OSTI]

    Yacobi, Ben G.

    1986-01-01

    A method for recording and storing information in a hydrogenated amorphous silicon device, comprising: depositing hydrogenated amorphous silicon on a substrate to form a charge-collection device; and generating defects in the hydrogenated amorphous silicon device, wherein the defects act as recombination centers that reduce the lifetime of carriers, thereby reducing charge-collection efficiency; and thus in the charge-collection mode of scanning probe instruments, regions of the hydrogenated amorphous silicon device that contain the defects appear darker in comparison to regions of the device that do not contain the defects, leading to a contrast formation for pattern recognition and information storage, in the device, which darkened areas can be restored to their original charge-collection efficiency by heating the hydrogenated amorphous silicon to a temperature of about 100.degree. C. to 250.degree. C. for a sufficient period of time to provide for such restoration.

  10. Highly featured amorphous silicon nanorod arrays for high-performance lithium-ion batteries

    SciTech Connect (OSTI)

    Soleimani-Amiri, Samaneh; Safiabadi Tali, Seied Ali; Azimi, Soheil; Sanaee, Zeinab; Mohajerzadeh, Shamsoddin

    2014-11-10

    High aspect-ratio vertical structures of amorphous silicon have been realized using hydrogen-assisted low-density plasma reactive ion etching. Amorphous silicon layers with the thicknesses ranging from 0.5 to 10 μm were deposited using radio frequency plasma enhanced chemical vapor deposition technique. Standard photolithography and nanosphere colloidal lithography were employed to realize ultra-small features of the amorphous silicon. The performance of the patterned amorphous silicon structures as a lithium-ion battery electrode was investigated using galvanostatic charge-discharge tests. The patterned structures showed a superior Li-ion battery performance compared to planar amorphous silicon. Such structures are suitable for high current Li-ion battery applications such as electric vehicles.

  11. Low hydrogen content, high quality hydrogenated amorphous silicon grown by hot-wire CVD

    SciTech Connect (OSTI)

    Nelson, B.P.; Crandall, R.S.; Iwaniczko, E.; Mahan, A.H.; Wang, Q.; Xu, Y.; Gao, W.

    1999-07-01

    The authors grow hydrogenated amorphous silicon (a-Si:H) by Hot-Wire Chemical Vapor Deposition (HWCVD). The early work with this technique has shown that they can grow a-Si:H that is different from typical a-Si:H materials. Specifically, they demonstrated the ability to grow a-Si:H of exceptional quality with very low hydrogen (H) contents (0.01 to 4 at.%). The deposition chambers in which this early work was done have two limitations; they hold only small-area substrates and they are incompatible with a load-lock. In the efforts to scale up to larger area chambers--that have load-lock compatibility--they encountered difficulty in growing high-quality films that also have a low H content. Substrate temperature has a direct effect on the H content of HWCVD grown a-Si:H. They found that making dramatic changes to the other deposition process parameters--at fixed substrate temperature and filament-to-substrate spacing--did not have much effect on the H content of the resulting films in the new chambers. However, these changes did have profound effects on film quality. They can grow high-quality a-Si:H in the new larger area chambers at 4 at. % H. For example, the lowest known stabilized defect density of a-Si:H is approximately 2 x 10{sup 16} cm{sup {minus}3}, which they have grown in the new chamber at 18 {angstrom}/s. Making changes to the original chamber--making it more like the new reactor--did not increase the hydrogen content at a fixed substrate temperature and filament-to-substrate spacing. They continued to grow high quality films with low H content in spite of these changes. An interesting, and very useful, result of these experiments is that the orientation of the filament with respect to silane flow direction had no influence on film quality or the H content of the films. The condition of the filament is much more important to growing quality films than the geometry of the chamber due to tungsten-silicide formation on the filament.

  12. Research on stable, high-efficiency amorphous silicon multijunction modules. Annual subcontract report, 1 December 1991--31 October 1992

    SciTech Connect (OSTI)

    Ghosh, M.; DelCueto, J.: Kampas, F.; Xi, J.

    1993-02-01

    This report describes results from the first phase of a three-phase contract for the development of stable, high-efficiency, same-band-gap, amorphous silicon (a-Si) multijunction photovoltaic (PV) modules. The program involved improving the properties of individual layers of semiconductor and non-semiconductor materials and small-area single-junction and multijunction devices, as well as the multijunction modules. The semiconductor materials research was performed on a-Si p, i, and n layers, and on microcrystalline silicon n layers. These were deposited using plasma-enhanced chemical vapor deposition. The non-semiconductor materials studied were tin oxide, for use as a transparent-conducting-oxide (TCO), and zinc oxide, for use as a back reflector and as a buffer layer between the TCO and the semiconductor layers. Tin oxide was deposited using atmospheric-pressure chemical vapor deposition. Zinc oxide was deposited using magnetron sputtering. The research indicated that the major challenge in the fabrication of a-Si multijunction PV modules is the contact between the two p-i-n cells. A structure that has low optical absorption but that also facilitates the recombination of electrons from the first p-i-n structure with holes from the second p-i-n structure is required. Non-semiconductor layers and a-Si semiconductor layers were tested without achieving the desired result.

  13. Deposition of device quality, low hydrogen content, amorphous silicon films by hot filament technique using ``safe`` silicon source gas

    DOE Patents [OSTI]

    Mahan, A.H.; Molenbroek, E.C.; Nelson, B.P.

    1998-07-07

    A method is described for producing hydrogenated amorphous silicon on a substrate by flowing a stream of safe (diluted to less than 1%) silane gas past a heated filament. 7 figs.

  14. See-through amorphous silicon solar cells with selectively transparent and conducting photonic crystal back reflectors for building integrated photovoltaics

    SciTech Connect (OSTI)

    Yang, Yang; OBrien, Paul G.; Materials Chemistry Research Group, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6 ; Ozin, Geoffrey A. E-mail: kherani@ecf.utoronto.ca; Kherani, Nazir P. E-mail: kherani@ecf.utoronto.ca

    2013-11-25

    Thin semi-transparent hydrogenated amorphous silicon (a-Si:H) solar cells with selectively transparent and conducting photonic crystal (STCPC) back-reflectors are demonstrated. Short circuit current density of a 135?nm thick a-Si:H cell with a given STCPC back-reflector is enhanced by as much as 23% in comparison to a reference cell with an ITO film functioning as its rear contact. Concurrently, solar irradiance of 295?W/m{sup 2} and illuminance of 3480 lux are transmitted through the cell with a given STCPC back reflector under AM1.5 Global tilt illumination, indicating its utility as a source of space heating and lighting, respectively, in building integrated photovoltaic applications.

  15. Research on stable, high-efficiency amorphous silicon multijunction modules. Final subcontract report, 1 January 1991--31 August 1994

    SciTech Connect (OSTI)

    Guha, S.

    1994-10-01

    The principal objective of this program is to conduct research on semiconductor materials and non-semiconductor materials to enhance the performance of multibandgap, multijunction, large-area amorphous silicon-based alloy modules. The goal for this program is to demonstrate stabilized module efficiency of 12% for multijunction modules of area greater than 900 cm{sup 2}. Double-junction and triple-junction cells are made on Ag/ZnO back reflector deposited on stainless steel substrates. The top cell uses a-Si alloy; a-SiGe alloy is used for the i layer in the middle and the bottom cells. After evaporation of antireflection coating, silver grids and bus bars are put on the top surface, and the panel is encapsulated in an ethylene vinyl acetate (EVA)/Tefzel structure to make a one-square-foot monolithic module.

  16. Optimization of transparent and reflecting electrodes for amorphous silicon solar cells. Annual subcontract report, April 1, 1994--March 31, 1995

    SciTech Connect (OSTI)

    Gordon, R.G.

    1995-10-01

    Transparent and reflecting electrodes are important parts of the structure of amorphous silicon solar cells. We report improved methods for depositing zinc oxide, deposition of tin nitride as a potential reflection-enhancing diffusion barrier between the a-Si and back metal electrodes. Highly conductive and transparent fluorine-doped zinc oxide was successfully produced on small areas by atmospheric pressure CVD from a less hazardous zinc precursor, zinc acetylacetonate. The optical properties measured for tin nitride showed that the back-reflection would be decreased if tin nitride were used instead of zinc oxide as a barrier layer over silver on aluminum. Niobium-doped titanium dioxide was produced with high enough electrical conductivity so that normal voltages and fill factors were obtained for a-Si cells made on it.

  17. Microstructure from joint analysis of experimental data and ab initio interactions: Hydrogenated amorphous silicon

    SciTech Connect (OSTI)

    Biswas, Parthapratim; Drabold, D. A.; Atta-Fynn, Raymond

    2014-12-28

    A study of the formation of voids and molecular hydrogen in hydrogenated amorphous silicon is presented based upon a hybrid approach that involves inversion of experimental nuclear magnetic resonance data in conjunction with ab initio total-energy relaxations in an augmented solution space. The novelty of this approach is that the voids and molecular hydrogen appear naturally in the model networks unlike conventional approaches, where voids are created artificially by removing silicon atoms from the networks. Two representative models with 16 and 18 at.?% of hydrogen are studied in this work. The result shows that the microstructure of the a-Si:H network consists of several microvoids and few molecular hydrogen for concentration above 15 at.?% H. The microvoids are highly irregular in shape and size, and have a linear dimension of 57?. The internal surface of a microvoid is found to be decorated with 49 hydrogen atoms in the form of monohydride SiH configurations as observed in nuclear magnetic resonance experiments. The microstructure consists of (0.91.4)% hydrogen molecules of total hydrogen in the networks. These observations are consistent with the outcome of infrared spectroscopy, nuclear magnetic resonance, and calorimetry experiments.

  18. Schottky barrier amorphous silicon solar cell with thin doped region adjacent metal Schottky barrier

    DOE Patents [OSTI]

    Carlson, David E.; Wronski, Christopher R.

    1979-01-01

    A Schottky barrier amorphous silicon solar cell incorporating a thin highly doped p-type region of hydrogenated amorphous silicon disposed between a Schottky barrier high work function metal and the intrinsic region of hydrogenated amorphous silicon wherein said high work function metal and said thin highly doped p-type region forms a surface barrier junction with the intrinsic amorphous silicon layer. The thickness and concentration of p-type dopants in said p-type region are selected so that said p-type region is fully ionized by the Schottky barrier high work function metal. The thin highly doped p-type region has been found to increase the open circuit voltage and current of the photovoltaic device.

  19. RF sputtering for controlling dihydride and monohydride bond densities in amorphous silicon hydride

    DOE Patents [OSTI]

    Jeffery, F.R.; Shanks, H.R.

    1980-08-26

    A process is described for controlling the dihydride and monohydride bond densities in hydrogenated amorphous silicone produced by reactive rf sputtering of an amorphous silicon target. There is provided a chamber with an amorphous silicon target and a substrate therein with the substrate and the target positioned such that when rf power is applied to the target the substrate is in contact with the sputtering plasma produced thereby. Hydrogen and argon are fed to the chamber and the pressure is reduced in the chamber to a value sufficient to maintain a sputtering plasma therein, and then rf power is applied to the silicon target to provide a power density in the range of from about 7 watts per square inch to about 22 watts per square inch to sputter an amorphous solicone hydride onto the substrate, the dihydride bond density decreasing with an increase in the rf power density. Substantially pure monohydride films may be produced.

  20. The silicon/zinc oxide interface in amorphous silicon-based thin-film solar cells: Understanding an empirically optimized contact

    SciTech Connect (OSTI)

    Gerlach, D.; Wilks, R. G.; Wimmer, M.; Felix, R.; Gorgoi, M.; Lips, K.; Rech, B.; Wippler, D.; Mueck, A.; Meier, M.; Huepkes, J.; Lozac'h, M.; Ueda, S.; Sumiya, M.; Yoshikawa, H.; Kobayashi, K.; Baer, M.

    2013-07-08

    The electronic structure of the interface between the boron-doped oxygenated amorphous silicon 'window layer' (a-SiO{sub x}:H(B)) and aluminum-doped zinc oxide (ZnO:Al) was investigated using hard x-ray photoelectron spectroscopy and compared to that of the boron-doped microcrystalline silicon ({mu}c-Si:H(B))/ZnO:Al interface. The corresponding valence band offsets have been determined to be (-2.87 {+-} 0.27) eV and (-3.37 {+-} 0.27) eV, respectively. A lower tunnel junction barrier height at the {mu}c-Si:H(B)/ZnO:Al interface compared to that at the a-SiO{sub x}:H(B)/ZnO:Al interface is found and linked to the higher device performances in cells where a {mu}c-Si:H(B) buffer between the a-Si:H p-i-n absorber stack and the ZnO:Al contact is employed.

  1. Research on stable, high-efficiency amorphous silicon multijunction modules

    SciTech Connect (OSTI)

    Guha, S. )

    1991-12-01

    This report describes research to improve the understanding of amorphous silicon alloys and other relevant non-semiconductor materials for use in high-efficiency, large-area multijunction modules. The research produced an average subcell initial efficiency of 8.8% over a 1-ft{sup 2} area using same-band-gap, dual-junction cells deposited over a ZnO/AlSi back reflector. An initial efficiency of 9.6% was achieved using a ZnO/Ag back reflector over smaller substrates. A sputtering machine will be built to deposit a ZnO/Ag back reflector over a 1-ft{sup 2} area so that a higher efficiency can also be obtained on larger substrates. Calculations have been performed to optimize the grid pattern, bus bars, and cell interconnects on modules. With our present state of technology, we expect a difference of about 6% between the aperture-area and active-area efficiencies of modules. Preliminary experiments show a difference of about 8%. We can now predict the performance of single-junction cells after long-term light exposure at 50{degree}C by exposing cells to short-term intense light at different temperatures. We find that single-junction cells deposited on a ZnO/Ag back reflector show the highest stabilized efficiency when the thickness of the intrinsic layers is about 2000 {angstrom}. 8 refs.

  2. Amorphous silicon cell array powered solar tracking apparatus

    DOE Patents [OSTI]

    Hanak, Joseph J.

    1985-01-01

    An array of an even number of amorphous silicon solar cells are serially connected between first and second terminals of opposite polarity. The terminals are connected to one input terminal of a DC motor whose other input terminal is connected to the mid-cell of the serial array. Vane elements are adjacent the end cells to selectively shadow one or the other of the end cells when the array is oriented from a desired attitude relative to the sun. The shadowing of one cell of a group of cells on one side of the mid-cell reduces the power of that group substantially so that full power from the group of cells on the other side of the mid-cell drives the motor to reorient the array to the desired attitude. The cell groups each have a full power output at the power rating of the motor. When the array is at the desired attitude the power output of the two groups of cells balances due to their opposite polarity so that the motor remains unpowered.

  3. Hot wire deposited hydrogenated amorphous silicon solar cells

    SciTech Connect (OSTI)

    Mahan, A.H.; Nelson, B.P.; Iwaniczko, E.; Wang, Q.; Molenbroek, E.C.; Asher, S.E.; Reedy, R.C. Jr.; Crandall, R.S.

    1996-01-01

    This paper details preliminary results obtained in incorporating low H content, high substrate temperature hot wire (HW) deposited amorphous silicon material into a substrate solar cell structure. By necessity, since the learning curve for this complete structure involves metal/{ital n}-{ital i}/Schottky barrier structure optimization, a large part of the results are focused on this (partial) structure. We have found that the treatment of the top surface of the HW {ital i} layer during cooling is crucial to device performance. Without any particular attention paid to the treatment of this surface while the sample is cooling from its high deposition temperature, a significant amount of H diffuses out of the sample during the cooling process, particularly near the surface, resulting in devices with very poor photovoltaic properties. By designing a surface treatment to address this problem, we have been able to deposit HW Schottky structures with device characteristics as good as the best glow discharge devices produced in our laboratory. We present data concerning these surface treatments, and how they influence the H content at the {ital i}/Pd interface. {copyright} {ital 1996 American Institute of Physics.}

  4. Amorphous silicon Schottky barrier solar cells incorporating a thin insulating layer and a thin doped layer

    DOE Patents [OSTI]

    Carlson, David E.

    1980-01-01

    Amorphous silicon Schottky barrier solar cells which incorporate a thin insulating layer and a thin doped layer adjacent to the junction forming metal layer exhibit increased open circuit voltages compared to standard rectifying junction metal devices, i.e., Schottky barrier devices, and rectifying junction metal insulating silicon devices, i.e., MIS devices.

  5. Amorphous silicon enhanced metal-insulator-semiconductor contacts for silicon solar cells

    SciTech Connect (OSTI)

    Bullock, J. Cuevas, A.; Yan, D.; Demaurex, B.; Hessler-Wyser, A.; De Wolf, S.

    2014-10-28

    Carrier recombination at the metal-semiconductor contacts has become a significant obstacle to the further advancement of high-efficiency diffused-junction silicon solar cells. This paper provides the proof-of-concept of a procedure to reduce contact recombination by means of enhanced metal-insulator-semiconductor (MIS) structures. Lightly diffused n{sup +} and p{sup +} surfaces are passivated with SiO{sub 2}/a-Si:H and Al{sub 2}O{sub 3}/a-Si:H stacks, respectively, before the MIS contacts are formed by a thermally activated alloying process between the a-Si:H layer and an overlying aluminum film. Transmission/scanning transmission electron microscopy (TEM/STEM) and energy dispersive x-ray spectroscopy are used to ascertain the nature of the alloy. Idealized solar cell simulations reveal that MIS(n{sup +}) contacts, with SiO{sub 2} thicknesses of ?1.55?nm, achieve the best carrier-selectivity producing a contact resistivity ?{sub c} of ?3 m? cm{sup 2} and a recombination current density J{sub 0c} of ?40 fA/cm{sup 2}. These characteristics are shown to be stable at temperatures up to 350?C. The MIS(p{sup +}) contacts fail to achieve equivalent results both in terms of thermal stability and contact characteristics but may still offer advantages over directly metallized contacts in terms of manufacturing simplicity.

  6. A comparison of the degradation and annealing kinetics in amorphous silicon and amorphous silicon-germanium solar cells

    SciTech Connect (OSTI)

    Carlson, D.E.; Chen, L.F.; Ganguly, G.; Lin, G.; Middya, A.R.; Crandall, R.S.; Reedy, R.

    1999-07-01

    The degradation and annealing kinetics of both a-Si:H and a-SiGe:H single-junction solar cells were investigated under varying conditions. In every case, the kinetics associated with degradation and annealing were slower for a-SiGe:H cells than for a a-Si:H cells. Since deuterium diffusion studies indicate that the hydrogen in the a-SiGe:H films diffuses more slowly than that in the a-Si:H films, hydrogen motion may play a role in determining both the degradation and annealing kinetics of the devices.

  7. a-Si:H Grown by Hot-Wire CVD at Ultra-High Deposition Rates

    SciTech Connect (OSTI)

    Xu, Y.; Nelson, B. P.; Mahan, A. H.; Williamson, D. L.; Crandall, R. S.; Iwaniczko, E.; Wang, Q.

    2000-01-01

    We increase the deposition rate of growing hydrogenated amorphous-silicon (a-Si:H) by the hot-wire chemical vapor depositon (HWCVD) technique by adding filaments (two) and decreasing the filament(s) to substrate distance.

  8. Research on high-efficiency, multiple-gap, multijunction, amorphous-silicon-based alloy thin-film solar cells

    SciTech Connect (OSTI)

    Guha, S. )

    1989-06-01

    This report presents results of research on advancing our understanding of amorphous-silicon-based alloys and their use in small-area multijunction solar cells. The principal objectives of the program are to develop a broad scientific base for the chemical, structural, optical, and electronic properties of amorphous-silicon-based alloys; to determine the optimum properties of these alloy materials as they relate to high-efficiency cells; to determine the optimum device configuration for multijunction cells; and to demonstrate proof-of-concept, multijunction, a-Si-alloy-based solar cells with 18% efficiency under standard AM1.5 global insolation conditions and with an area of at least 1 cm{sup 2}. A major focus of the work done during this reporting period was the optimization of a novel, multiple-graded structure that enhances cell efficiency through band-gap profiling. The principles of the operation of devices incorporating such a structure, computer simulations of those, and experimental results for both single- and multijunction cells prepared by using the novel structure are discussed in detail. 14 refs., 35 figs., 7 tabs.

  9. Internal Friction of Amorphous and Nanocrystalline Silicon Containing Hydrogen: Preprint

    SciTech Connect (OSTI)

    Merithew, R. D.; Liu, X.; Wang, Q.; Crandall, R. S.; Pohl, R. O.

    2001-10-01

    Presented at the 2001 NCPV Program Review Meeting: Using methods of elastic properties to study disorder of thin silicon films.

  10. Atomic Layer Deposition for Stabilization of Amorphous Silicon...

    Broader source: Energy.gov (indexed) [DOE]

    More Documents & Publications Nanostructured Metal Oxide Anodes Atomic Layer Deposition for Stabilization of Silicon Anodes Development of Industrially Viable Battery Electrode ...

  11. Hybrid method of making an amorphous silicon P-I-N semiconductor device

    DOE Patents [OSTI]

    Moustakas, Theodore D.; Morel, Don L.; Abeles, Benjamin

    1983-10-04

    The invention is directed to a hydrogenated amorphous silicon PIN semiconductor device of hybrid glow discharge/reactive sputtering fabrication. The hybrid fabrication method is of advantage in providing an ability to control the optical band gap of the P and N layers, resulting in increased photogeneration of charge carriers and device output.

  12. Amorphous silicon research. Annual subcontract report, October 1, 1994--September 30, 1995

    SciTech Connect (OSTI)

    Arya, R.R.; Bennett, M.; Bradley, D.

    1996-02-01

    The major effort in this program is to develop cost-effective processes which satisfy efficiency, yield, and material usage criteria for mass production of amorphous silicon-based multijunction modules. New and improved processes were developed for the component cells and a more robust rear contact was developed for better long term stability.

  13. Method of forming semiconducting amorphous silicon films from the thermal decomposition of fluorohydridodisilanes

    DOE Patents [OSTI]

    Sharp, Kenneth G.; D'Errico, John J.

    1988-01-01

    The invention relates to a method of forming amorphous, photoconductive, and semiconductive silicon films on a substrate by the vapor phase thermal decomposition of a fluorohydridodisilane or a mixture of fluorohydridodisilanes. The invention is useful for the protection of surfaces including electronic devices.

  14. Size effects on the thermal conductivity of amorphous silicon thin films

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Thomas Edwin Beechem; Braun, Jeffrey L.; Baker, Christopher H.; Elahi, Miraz; Artyushkova, Kateryna; Norris, Pamela M.; Leseman, Zayd Chad; Gaskins, John T.; Hopkins, Patrick E.; Giri, Ashutosh

    2016-04-01

    In this study, we investigate thickness-limited size effects on the thermal conductivity of amorphous silicon thin films ranging from 3 to 1636 nm grown via sputter deposition. While exhibiting a constant value up to ~100 nm, the thermal conductivity increases with film thickness thereafter. The thickness dependence we demonstrate is ascribed to boundary scattering of long wavelength vibrations and an interplay between the energy transfer associated with propagating modes (propagons) and nonpropagating modes (diffusons). A crossover from propagon to diffuson modes is deduced to occur at a frequency of ~1.8 THz via simple analytical arguments. These results provide empirical evidencemore » of size effects on the thermal conductivity of amorphous silicon and systematic experimental insight into the nature of vibrational thermal transport in amorphous solids.« less

  15. Amorphous/crystalline silicon interface passivation: Ambient-temperature dependence and implications for solar cell performance

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Seif, Johannes P.; Krishnamani, Gopal; Demaurex, Benedicte; Ballif, Christophe; Wolf, Stefaan De

    2015-03-02

    Silicon heterojunction (SHJ) solar cells feature amorphous silicon passivation films, which enable very high voltages. We report how such passivation increases with operating temperature for amorphous silicon stacks involving doped layers and decreases for intrinsic-layer-only passivation. We discuss the implications of this phenomenon on the solar cell's temperature coefficient, which represents an important figure-of-merit for the energy yield of devices deployed in the field. We show evidence that both open-circuit voltage (Voc) and fill factor (FF) are affected by these variations in passivation and quantify these temperature-mediated effects, compared with those expected from standard diode equations. We confirm that devicesmore » with high Voc values at 25°C show better high-temperature performance. Thus, we also argue that the precise device architecture, such as the presence of charge-transport barriers, may affect the temperature-dependent device performance as well.« less

  16. Amorphous/crystalline silicon interface passivation: Ambient-temperature dependence and implications for solar cell performance

    SciTech Connect (OSTI)

    Seif, Johannes P.; Krishnamani, Gopal; Demaurex, Benedicte; Ballif, Christophe; Wolf, Stefaan De

    2015-03-02

    Silicon heterojunction (SHJ) solar cells feature amorphous silicon passivation films, which enable very high voltages. We report how such passivation increases with operating temperature for amorphous silicon stacks involving doped layers and decreases for intrinsic-layer-only passivation. We discuss the implications of this phenomenon on the solar cell's temperature coefficient, which represents an important figure-of-merit for the energy yield of devices deployed in the field. We show evidence that both open-circuit voltage (Voc) and fill factor (FF) are affected by these variations in passivation and quantify these temperature-mediated effects, compared with those expected from standard diode equations. We confirm that devices with high Voc values at 25°C show better high-temperature performance. Thus, we also argue that the precise device architecture, such as the presence of charge-transport barriers, may affect the temperature-dependent device performance as well.

  17. Amorphous/crystalline silicon interface passivation: Ambient-temperature dependence and implications for solar cell performance

    SciTech Connect (OSTI)

    Seif, Johannes P.; Krishnamani, Gopal; Demaurex, Benedicte; Ballif, Christophe; Wolf, Stefaan De

    2015-03-02

    Silicon heterojunction (SHJ) solar cells feature amorphous silicon passivation films, which enable very high voltages. We report how such passivation increases with operating temperature for amorphous silicon stacks involving doped layers and decreases for intrinsic-layer-only passivation. We discuss the implications of this phenomenon on the solar cell's temperature coefficient, which represents an important figure-of-merit for the energy yield of devices deployed in the field. We show evidence that both open-circuit voltage (Voc) and fill factor (FF) are affected by these variations in passivation and quantify these temperature-mediated effects, compared with those expected from standard diode equations. We confirm that devices with high Voc values at 25C show better high-temperature performance. Thus, we also argue that the precise device architecture, such as the presence of charge-transport barriers, may affect the temperature-dependent device performance as well.

  18. Saturated defect densities of hydrogenated amorphous silicon grown by hot-wire chemical vapor deposition at rates up to 150 {angstrom}/s

    SciTech Connect (OSTI)

    Mahan, A. H.; Xu, Y.; Nelson, B. P.; Crandall, R. S.; Cohen, J. D.; Palinginis, K. C.; Gallagher, A. C.

    2001-06-11

    Hydrogenated amorphous-silicon (a-Si:H) is grown by hot-wire chemical vapor deposition (HWCVD) at deposition rates (R{sub d}) exceeding 140 {angstrom}/s ({approx}0.8 {mu}m/min). These high rates are achieved by using multiple filaments and deposition conditions different than those used to produce our standard 20 {angstrom}/s material. With proper deposition parameter optimization, an AM1.5 photo-to-dark-conductivity ratio of 10{sup 5} is maintained at an R{sub d} up to 130 {angstrom}/s, beyond which it decreases. In addition, the first saturated defect densities of high R{sub d} a-Si:H films are presented. These saturated defected densities are similar to those of the best HWCVD films deposited at 5--8 {angstrom}/s, and are invariant with R{sub d} up to 130 {angstrom}/s.

  19. Determination of defect density of state distribution of amorphous silicon solar cells by temperature derivative capacitance-frequency measurement

    SciTech Connect (OSTI)

    Yang, Guangtao Swaaij, R. A. C. M. M. van; Dobrovolskiy, S.; Zeman, M.

    2014-01-21

    In this contribution, we demonstrate the application temperature dependent capacitance-frequency measurements (C-f) to n-i-p hydrogenated amorphous silicon (a-Si:H) solar cells that are forward-biased. By using a forward bias, the C-f measurement can detect the density of defect states in a particular energy range of the interface region. For this contribution, we have carried out this measurement method on n-i-p a-Si:H solar cells of which the intrinsic layer has been exposed to a H{sub 2}-plasma before p-type layer deposition. After this treatment, the open-circuit voltage and fill factor increased significantly, as well as the blue response of the solar cells as is concluded from external quantum efficiency. For single junction, n-i-p a-Si:H solar cells initial efficiency increased from 6.34% to 8.41%. This performance enhancement is believed to be mainly due to a reduction of the defect density in the i-p interface region after the H{sub 2}-plasma treatment. These results are confirmed by the C-f measurements. After H{sub 2}-plasma treatment, the defect density in the intrinsic layer near the i-p interface region is lower and peaks at an energy level deeper in the band gap. These C-f measurements therefore enable us to monitor changes in the defect density in the interface region as a result of a hydrogen plasma. The lower defect density at the i-p interface as detected by the C-f measurements is supported by dark current-voltage measurements, which indicate a lower carrier recombination rate.

  20. All-Hot-Wire Chemical Vapor Deposition a-Si:H Solar Cells

    SciTech Connect (OSTI)

    Iwaniczko, E.; Wang, Q.; Xu, Y.; Nelson, B. P.; Mahan, A. H.; Crandall, R. S.; Branz, H. M.

    2000-01-01

    Efficient hydrogenated amorphous silicon (a-Si:H) nip solar cells have been fabricated with all doped and undoped a-Si:H layers deposited by hot-wire chemical vapor deposition (HWCVD). The total deposition time of all layers, except the top ITO-contact, is less than 4 minutes.

  1. Impact of the hydrogen content on the photoluminescence efficiency of amorphous silicon alloys

    SciTech Connect (OSTI)

    Kistner, J.; Schubert, M. B.

    2013-12-07

    This paper analyzes the impact of hydrogen on the photoluminescence (PL) efficiency of the three wide gap silicon alloys: silicon carbide (a-SiC{sub x}), silicon nitride (a-SiN{sub x}): silicon oxide (a-SiO{sub x}). All three materials behave similarly. The progression of the PL efficiency over the Si content splits into two regions. With decreasing Si content, the PL efficiency increases until a maximum is reached. With a further decrease of the Si content, the PL efficiency declines again. A comprehensive analysis of the sample structure reveals that the PL efficiency depends on the degree of passivation of Si and Y atoms (Y?=?C, N, O) with hydrogen. For samples with a high Si content, an effective passivation of incorporated Y atoms gives rise to an increasing PL efficiency. The PL efficiency of samples with a low Si content is limited due to a rising amount of unpassivated Si defect states. We find that a minimum amount of 0.2?H atoms per Si atom is required to maintain effective luminescence.

  2. Efficient Crystalline Si Solar Cell with Amorphous/Crystalline Silicon Heterojunction as Back Contact: Preprint

    SciTech Connect (OSTI)

    Nemeth, B.; Wang, Q.; Shan, W.

    2012-06-01

    We study an amorphous/crystalline silicon heterojunction (Si HJ) as a back contact in industrial standard p-type five-inch pseudo-square wafer to replace Al back surface field (BSF) contact. The best efficiency in this study is over 17% with open-circuit (Voc) of 0.623 V, which is very similar to the control cell with Al BSF. We found that Voc has not been improved with the heterojunction structure in the back. The typical minority carrier lifetime of these wafers is on the order of 10 us. We also found that the doping levels of p-layer affect the FF due to conductivity and band gap shifting, and an optimized layer is identified. We conclude that an amorphous/crystalline silicon heterojunction can be a very promising structure to replace Al BSF back contact.

  3. Medium-range order in hydrogenated amorphous silicon measured by fluctuation microscopy

    SciTech Connect (OSTI)

    Voyles, P. M.; Treacy, M. M. J.; Jin, H.-C.; Abelson, J. R.; Gibson, J. M.; Guha, S.; Crandall, R. S.

    2000-04-17

    The authors have characterized with fluctuation electron microscopy the medium-range order of hydrogenated amorphous silicon thin films deposited by a variety of methods. Films were deposited by reactive magnetron sputtering, hot-wire chemical vapor deposition, and plasma enhanced chemical vapor deposition with and without H{sub 2} dilution of the SiH{sub 4} precursor gas. All of the films show the signature of the paracrystalline structure typical of amorphous Si. There are small variations in the degree of medium-range order with deposition methods and H{sub 2} content. The PECVD film grown with high H{sub 2} dilution contains Si crystals {approximately} 5 nm in diameter at a density of {approximately} 10{sup 9} cm{sup 2}. The amorphous matrix surrounding these crystals shows no difference in medium-range order from the standard PECVD film.

  4. Amorphous Solid without Low Energy Excitations

    SciTech Connect (OSTI)

    Liu, X.; White, B.E. Jr.; Pohl, R.O.; Iwanizcko, E.; Jones, K.M.; Mahan, A.H.; Nelson, B.N.; Crandall, R.S.; Veprek, S.

    1997-06-01

    We have measured the low temperature internal friction (Q{sup -1}) of amorphous silicon (a-Si) films. {ital e}-beam evaporation or {sup 28}Si{sup +} implantation leads to the temperature-independent Q{sup -1}{sub 0} plateau common to all amorphous solids. For hydrogenated amorphous silicon with 1 at. {percent} H produced by hot wire chemical vapor deposition, however, Q{sup -1}{sub 0} is over 200 times smaller than for {ital e}-beam {ital a}-Si. This is the first observation of an amorphous solid without any significant low energy excitations. It offers the opportunity to study amorphous solids containing controlled densities of tunneling defects, and thus to explore their nature. {copyright} {ital 1997} {ital The American Physical Society}

  5. Method of controllong the deposition of hydrogenated amorphous silicon and apparatus therefor

    DOE Patents [OSTI]

    Hanak, Joseph J. (Lawrenceville, NJ)

    1985-06-25

    An improved method and apparatus for the controlled deposition of a layer of hydrogenated amorphous silicon on a substrate. Means is provided for the illumination of the coated surface of the substrate and measurement of the resulting photovoltage at the outermost layer of the coating. Means is further provided for admixing amounts of p type and n type dopants to the reactant gas in response to the measured photovoltage to achieve a desired level and type of doping of the deposited layer.

  6. Niobium nitride-niobium Josephson tunnel junctions with sputtered amorphous silicon barriers

    SciTech Connect (OSTI)

    Jillie, D.W.; Kroger, H.; Smith, L.N.; Cukauskas, E.J.; Nisenoff, M.

    1982-04-15

    Niobium nitride-niobium Josephson tunnel junctions with sputtered amorphous silicon barriers (NbN-..cap alpha..Si-Nb) have been prepared using processing that is fully compatible with integrated circuit fabrication. These junctions are of suitable quality and uniformity for digital circuit and S-I-S detector applications. The junction quality depends critically upon the properties of the NbN surface, and seems to correlate well with the UV/visible reflectivity of this surface.

  7. Residual strains in amorphous silicon films measured by x-ray double crystal topography

    SciTech Connect (OSTI)

    Kuo, C.L.; Vanier, P.E.; Bilello, J.C.

    1984-01-15

    A new application of double crystal topography using selected diffraction from portions of bent crystals was used to determine the curvature of single crystal Si wafers coated with hydrogenated amorphous Si (a-Si:H) films. This direct imaging method allowed measurements of the radii of curvature R of bent crystals over a range approx. =0.2--1000 m. Using this procedure two different series of a-Si:H films were measured to compare the internal strains and monitor these as a function of film thickness. The curvature of the sample crystals was shown to be inversely proportional to the thickness of the film. The internal stress was found to be independent of film thickness, but only depended on the processing conditions.

  8. Transport properties of intrinsic hydrogenated amorphous silicon produced by the hot-wire technique investigated by the photomixing technique

    SciTech Connect (OSTI)

    Dong, S.; Tang, Y.; Liebe, J.; Braunstein, R.; Crandall, R.S.; Nelson, B.P.; Mahan, A.H.

    1997-07-01

    The transport properties of hydrogenated amorphous silicon (a-Si:H) with a hydrogen content ranging from 12{percent} to less than 1{percent}, which were produced by the hot-wire technique, varying the deposition substrate temperature, 290{degree}C{lt}T{sub S}{lt}400{degree}C, were systematically studied by the photoconductive frequency mixing technique. With an increase of the deposition substrate temperature, and consequent decrease of hydrogen content, the photoconductivity, {sigma}{sub pc}, and the drift mobility, {mu}{sub d}, are found to decrease, while the width of the conduction band tail, {epsilon}, increases. Continuous degradations of photoconductivity, drift mobility, and photomixing lifetime, {tau}, were found during light soaking experiments. In addition, it was found that the drift mobility increases and the photomixing lifetime decreases with an increase of the applied electric field, while the photoconductivity is essentially independent of the electric field within the range of 1000{endash}10000Vcm{sup {minus}1}. Furthermore, the electric field dependence of the drift mobility in the annealed state is always larger than in the light-soaked state. The results for the electric field dependence are explained using the model of long-range potential fluctuations, whose range can be determined by employing an analysis previously developed. {copyright} {ital 1997 American Institute of Physics.}

  9. The correlation of open-circuit voltage with bandgap in amorphous silicon-based {ital pin} solar cells

    SciTech Connect (OSTI)

    Crandall, R.S.; Schiff, E.A.

    1996-01-01

    We briefly review the correlation of open-circuit voltages {ital V}{sub OC} with the bandgap of the intrinsic layer in amorphous silicon based {ital pin} solar cells. We discuss two mechanisms which limit {ital V}{sub OC}: intrinsic layer recombination, and the built-in potential {ital V}{sub BI}. In particular we discuss Li{close_quote}s proposal that the open-circuit voltages in higher bandgap cells ({ital E}{sub G}{gt}1.9 eV) are {ital V}{sub BI}-limited. Based on computer simulations of {ital pin} solar cells we propose that {ital V}{sub BI} limitation occurs when the recombination limit to {ital V}{sub OC} exceeds the cell{close_quote}s field-reversal voltage {ital V}{sub R}. For {ital a}-Si:H based cells this field-reversal voltage occurs at about {ital V}{sub BI}-0.3 V. This proposal would account for the observation that {ital V}{sub BI} limitation occurs for {ital V}{sub OC} significantly smaller than {ital V}{sub BI}. {copyright} {ital 1996 American Institute of Physics.}

  10. High efficiency multijunction amorphous silicon alloy-based solar cells and modules

    SciTech Connect (OSTI)

    Guha, S.; Yang, J.; Banerjeee, A.; Glatfelter, T.; Hoffman, K.; Xu, X. )

    1994-06-30

    We have achieved initial efficiency of 11.4% as confirmed by National Renewable Energy Laboratory (NREL) on a multijunction amorphous silicon alloy photovoltaic module of one-square-foot-area. [bold This] [bold is] [bold the] [bold highest] [bold initial] [bold efficiency] [bold confirmed] [bold by] [bold NREL] [bold for] [bold any] [bold thin] [bold film] [bold photovoltaic] [bold module]. After light soaking for 1000 hours at 50 [degree]C under one-sun illumination, a module with initial efficiency of 11.1% shows a stabilized efficiency of 9.5%. Key factors that led to this high performance are discussed.

  11. Tunneling through amorphous silicon barriers. Final report, July 1982-August 1983

    SciTech Connect (OSTI)

    Kroger, H.; Smith, L.N.; Jillie, D.W.; Thaxter, J.B.

    1983-10-01

    Substantial evidence has been accumulated during the course of this program which indicates that the localized states which are present in nonhydrogenated sputtered amorphous silicon barriers contribute to the larger current density observed at biases below the superconducting energy gap of the electrodes. The basic observations and the method of measuring the density of localized states at the Fermi level of the barrier materials are presented in the Appendix which is a reprint of a paper presented at the 1982 Superconductivity Conference. More recent observations and theoretical speculations are included in this report.

  12. The influence of charge effect on the growth of hydrogenated amorphous silicon by the hot-wire chemical vapor deposition technique

    SciTech Connect (OSTI)

    Wang, Q.; Nelson, B.P.; Iwaniczko, E.; Mahan, A.H.; Crandall, R.S.; Benner, J.

    1998-09-01

    The authors observe at lower substrate temperatures that the scatter in the dark conductivity on hydrogenated amorphous silicon (a-Si:H) films grown on insulating substrates (e.g., Corning 7059 glass) by the hot-wire chemical vapor deposition technique (HWCVD) can be five orders of magnitude or more. This is especially true at deposition temperatures below 350 C. However, when the authors grow the same materials on substrates with a conductive grid, virtually all of their films have acceptable dark conductivity (< 5 {times} 10{sup {minus}10} S/cm) at all deposition temperatures below 425 C. This is in contrast to only about 20% of the materials grown in this same temperature range on insulating substrates having an acceptable dark conductivity. The authors estimated an average energy of 5 eV electrons reaching the growing surface in vacuum, and did additional experiments to see the influence of both the electron flux and the energy of the electrons on the film growth. Although these effects do not seem to be important for growing a-Si:H by HWCVD on conductive substrates, they help better understand the important parameters for a-Si:H growth, and thus, to optimize these parameters in other applications of HWCVD technology.

  13. Method for sputtering a PIN microcrystalline/amorphous silicon semiconductor device with the P and N-layers sputtered from boron and phosphorous heavily doped targets

    DOE Patents [OSTI]

    Moustakas, Theodore D.; Maruska, H. Paul

    1985-04-02

    A silicon PIN microcrystalline/amorphous silicon semiconductor device is constructed by the sputtering of N, and P layers of silicon from silicon doped targets and the I layer from an undoped target, and at least one semi-transparent ohmic electrode.

  14. Method of enhancing the electronic properties of an undoped and/or N-type hydrogenated amorphous silicon film

    DOE Patents [OSTI]

    Carlson, David E.

    1980-01-01

    The dark conductivity and photoconductivity of an N-type and/or undoped hydrogenated amorphous silicon layer fabricated by an AC or DC proximity glow discharge in silane can be increased through the incorporation of argon in an amount from 10 to about 90 percent by volume of the glow discharge atmosphere which contains a silicon-hydrogen containing compound in an amount of from about 90 to about 10 volume percent.

  15. Microstructure factor and mechanical and electronic properties of hydrogenated amorphous and nanocrystalline silicon thin-films for microelectromechanical systems applications

    SciTech Connect (OSTI)

    Mouro, J.; Gualdino, A.; Chu, V. [Instituto de Engenharia de Sistemas e Computadores Microsistemas e Nanotecnologias (INESC-MN) and IN Institute of Nanoscience and Nanotechnology, 1000-029 Lisbon (Portugal); Conde, J. P. [Instituto de Engenharia de Sistemas e Computadores Microsistemas e Nanotecnologias (INESC-MN) and IN Institute of Nanoscience and Nanotechnology, 1000-029 Lisbon (Portugal); Department of Bioengineering, Instituto Superior Tcnico (IST), 1049-001 Lisbon (Portugal)

    2013-11-14

    Thin-film silicon allows the fabrication of MEMS devices at low processing temperatures, compatible with monolithic integration in advanced electronic circuits, on large-area, low-cost, and flexible substrates. The most relevant thin-film properties for applications as MEMS structural layers are the deposition rate, electrical conductivity, and mechanical stress. In this work, n{sup +}-type doped hydrogenated amorphous and nanocrystalline silicon thin-films were deposited by RF-PECVD, and the influence of the hydrogen dilution in the reactive mixture, the RF-power coupled to the plasma, the substrate temperature, and the deposition pressure on the structural, electrical, and mechanical properties of the films was studied. Three different types of silicon films were identified, corresponding to three internal structures: (i) porous amorphous silicon, deposited at high rates and presenting tensile mechanical stress and low electrical conductivity, (ii) dense amorphous silicon, deposited at intermediate rates and presenting compressive mechanical stress and higher values of electrical conductivity, and (iii) nanocrystalline silicon, deposited at very low rates and presenting the highest compressive mechanical stress and electrical conductivity. These results show the combinations of electromechanical material properties available in silicon thin-films and thus allow the optimized selection of a thin silicon film for a given MEMS application. Four representative silicon thin-films were chosen to be used as structural material of electrostatically actuated MEMS microresonators fabricated by surface micromachining. The effect of the mechanical stress of the structural layer was observed to have a great impact on the device resonance frequency, quality factor, and actuation force.

  16. Investigation of structural and electrical properties of flat a-Si/c-Si heterostructure fabricated by EBPVD technique

    SciTech Connect (OSTI)

    Demiro?lu, D.; Tatar, B.; Kazmanli, K.; Urgen, M.

    2013-12-16

    Flat amorphous silicon - crystal silicon (a-Si/c-Si) heterostructure were prepared by ultra-high vacuum electron beam evaporation technique on p-Si (111) and n-Si (100) single crystal substrates. Structural analyses were investigated by XRD, Raman and FEG-SEM analysis. With these analyses we determined that at the least amorphous structure shows modification but amorphous structure just protected. The electrical and photovoltaic properties of flat a-Si/c-Si heterojunction devices were investigated with current-voltage characteristics under dark and illumination conditions. Electrical properties of flat a-Si/c-Si heterorojunction; such as barrier height ?{sub B}, diode ideality factor ? were determined from current-voltage characteristics in dark conditions. These a-Si/c-Si heterostructure have good rectification behavior as a diode and exhibit high photovoltaic sensitivity.

  17. Picosecond and nanosecond laser annealing and simulation of amorphous silicon thin films for solar cell applications

    SciTech Connect (OSTI)

    Theodorakos, I.; Zergioti, I.; Tsoukalas, D.; Raptis, Y. S.; Vamvakas, V.

    2014-01-28

    In this work, a picosecond diode pumped solid state laser and a nanosecond Nd:YAG laser have been used for the annealing and the partial nano-crystallization of an amorphous silicon layer. These experiments were conducted as an alternative/complementary to plasma-enhanced chemical vapor deposition method for fabrication of micromorph tandem solar cell. The laser experimental work was combined with simulations of the annealing process, in terms of temperature distribution evolution, in order to predetermine the optimum annealing conditions. The annealed material was studied, as a function of several annealing parameters (wavelength, pulse duration, fluence), as far as it concerns its structural properties, by X-ray diffraction, SEM, and micro-Raman techniques.

  18. Light-induced increase in two-level tunneling states in hydrogenated amorphous silicon

    SciTech Connect (OSTI)

    Liu, X.; Pohl, R.O.; Crandall, R.S.

    1999-07-01

    The authors observe an increase of the low-temperature internal friction of hydrogenated amorphous silicon prepared by both hot-wire and plasma-enhanced chemical-vapor deposition after extended light-soaking at room temperature. This increase, and the associated change in sound velocity, can be explained by an increase of the density of two-level tunneling states, which serves as a measure of the lattice disorder. The amount of increase in internal friction is remarkably similar in both types of films although the amount and the microstructure of hydrogen are very different. Experiments conducted on a sample prepared by hot-wire chemical-vapor deposition show that this change anneals out gradually at room temperature in about 70 days. Possible relation of the light-induced changes in the low-temperature elastic properties to the Staebler-Wronski effect is discussed.

  19. Advances in amorphous silicon alloy-based multijunction cells and modules

    SciTech Connect (OSTI)

    Guha, S.; Yang, J.; Banerjee, A.; Glatfelter, T.; Xu, X. )

    1992-12-01

    Multijunction amorphous silicon alloy-based solar cells and modules offer the potential of obtaining high efficiency with long-term stability against light-induced degradation. We have studied the stability of the component cells of the multijunction devices prepared under different deposition conditions. We observe a definite correlation between the microstructure of the intrinsic material and initial and light-degraded performance of the cells. Using suitable deposition conditions and optimum matching of the component cells, we have fabricated double-junction dual-bandgap cells which show stabilized active-area efficiency of 11% after 600 hours of one-sun illumination at 50 [degree]C. Double-junction and triple-junction modules of 900 cm[sup 2] area have been fabricated, and the performance of these panels will be discussed.

  20. Identifying Electronic Properties Relevant to Improving the Performance and Stability of Amorphous Silicon Based Photovoltaic Cells: Final Subcontract Report, 27 November 2002--31 March 2005

    SciTech Connect (OSTI)

    Cohen, J. D.

    2005-11-01

    A major effort during this subcontract period has been to evaluate the microcrystalline Si material under development at United Solar Ovonics Corporation (USOC). This material is actually a hydrogenated nanocrystalline form of Si and it will be denoted in this report as nc-Si:H. Second, we continued our studies of the BP Solar high-growth samples. Third, we evaluated amorphous silicon-germanium alloys produced by the hot-wire chemical vapor deposition growth process. This method holds some potential for higher deposition rate Ge alloy materials with good electronic properties. In addition to these three major focus areas, we examined a couple of amorphous germanium (a-Ge:H) samples produced by the ECR method at Iowa State University. Our studies of the electron cyclotron resonance a-Ge:H indicated that the Iowa State a Ge:H material had quite superior electronic properties, both in terms of the drive-level capacitance profiling deduced defect densities, and the transient photocapacitance deduced Urbach energies. Also, we characterized several United Solar a Si:H samples deposited very close to the microcrystalline phase transition. These samples exhibited good electronic properties, with midgap defect densities slightly less than 1 x 1016 cm-3 in the fully light-degraded state.

  1. Saturated defect densities of hydrogenated amorphous silicon grown by hot-wire chemical vapor deposition at rates up to 150 Aa/s

    SciTech Connect (OSTI)

    Mahan, A. H.; Xu, Y.; Nelson, B. P.; Crandall, R. S.; Cohen, J. D.; Palinginis, K. C.; Gallagher, A. C.

    2001-06-11

    Hydrogenated amorphous-silicon (a-Si:H) is grown by hot-wire chemical vapor deposition (HWCVD) at deposition rates (R{sub d}) exceeding 140 Aa/s ({similar_to}0.8 {mu}m/min). These high rates are achieved by using multiple filaments and deposition conditions different than those used to produce our standard 20 Aa/s material. With proper deposition parameter optimization, an AM1.5 photo-to-dark-conductivity ratio of 10{sup 5} is maintained at an R{sub d} up to 130 Aa/s, beyond which it decreases. In addition, the first saturated defect densities of high R{sub d} a-Si:H films are presented. These saturated defected densities are similar to those of the best HWCVD films deposited at 5{endash}8 Aa/s, and are invariant with R{sub d} up to 130 Aa/s. {copyright} 2001 American Institute of Physics.

  2. In-situ high resolution transmission electron microscopy observation of silicon nanocrystal nucleation in a SiO{sub 2} bilayered matrix

    SciTech Connect (OSTI)

    Yang, T. C.-J. Wu, L.; Lin, Z.; Jia, X.; Puthen-Veettil, B.; Zhang, T.; Conibeer, G.; Perez-Wurfl, I.; Kauffmann, Y.; Rothschild, A.

    2014-08-04

    Solid-state nucleation of Si nanocrystals in a SiO{sub 2} bilayered matrix was observed at temperatures as low as 450?C. This was achieved by aberration corrected high-resolution transmission electron microscopy (HRTEM) with real-time in-situ heating up to 600?C. This technique is a valuable characterization tool especially with the recent interest in Si nanostructures for light emitting devices, non-volatile memories, and third-generation photovoltaics which all typically require a heating step in their fabrication. The control of size, shape, and distribution of the Si nanocrystals are critical for these applications. This experimental study involves in-situ observation of the nucleation of Si nanocrystals in a SiO{sub 2} bilayered matrix fabricated through radio frequency co-sputtering. The results show that the shapes of Si nanocrystals in amorphous SiO{sub 2} bilayered matrices are irregular and not spherical, in contrast to many claims in the literature. Furthermore, the Si nanocrystals are well confined within their layers by the amorphous SiO{sub 2}. This study demonstrates the potential of in-situ HRTEM as a tool to observe the real time nucleation of Si nanocrystals in a SiO{sub 2} bilayered matrix. Furthermore, ideas for improvements on this in-situ heating HRTEM technique are discussed.

  3. Increasing Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

    DOE Patents [OSTI]

    Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

    1999-08-24

    High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

  4. Increased Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

    DOE Patents [OSTI]

    Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

    1997-07-08

    High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

  5. Method for sputtering a PIN amorphous silicon semi-conductor device having partially crystallized P and N-layers

    DOE Patents [OSTI]

    Moustakas, Theodore D.; Maruska, H. Paul

    1985-07-09

    A high efficiency amorphous silicon PIN semiconductor device having partially crystallized (microcrystalline) P and N layers is constructed by the sequential sputtering of N, I and P layers and at least one semi-transparent ohmic electrode. The method of construction produces a PIN device, exhibiting enhanced electrical and optical properties, improved physical integrity, and facilitates the preparation in a singular vacuum system and vacuum pump down procedure.

  6. Manipulating hybrid structures of polymer/a-Si for thin film solar cells

    SciTech Connect (OSTI)

    Peng, Ying; He, Zhiqun, E-mail: zhqhe@bjtu.edu.cn, E-mail: J.I.B.Wilson@hw.ac.uk; Zhang, Zhi; Liang, Chunjun [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing 100044 (China); Diyaf, Adel; Ivaturi, Aruna; Wilson, John I. B., E-mail: zhqhe@bjtu.edu.cn, E-mail: J.I.B.Wilson@hw.ac.uk [SUPA, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

    2014-03-10

    A series of uniform polymer/amorphous silicon hybrid structures have been fabricated by means of solution-casting for polymer and radio frequency excited plasma enhanced chemical vapour deposition for amorphous silicon (a-Si:H). Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) functioned as a photoactive donor, while the silicon layer acted as an acceptor. It is found that matching the hole mobility of the polymer to the electron mobility of amorphous silicon is critical to improve the photovoltaic performance from hybrid cells. A three-layer p-i-n structure of ITO/PEDOT:PSS(200?nm)/i-Si(450?nm)/n-Si(200?nm)/Al with a power conversion efficiency of 4.78% under a standard test condition was achieved.

  7. Low-temperature high-mobility amorphous IZO for silicon heterojunction solar cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Morales-Masis, Monica; Martin De Nicolas, Silvia; Holovsky, Jakub; De Wolf, Stefaan; Ballif, Christophe

    2015-07-13

    Parasitic absorption in the transparent conductive oxide (TCO) front electrode is one of the limitations of silicon heterojunction (SHJ) solar cells efficiency. To avoid such absorption while retaining high conductivity, TCOs with high electron mobility are preferred over those with high carrier density. Here, we demonstrate improved SHJ solar cell efficiencies by applying high-mobility amorphous indium zinc oxide (a-IZO) as the front TCO. We sputtered a-IZO at low substrate temperature and low power density and investigated the optical and electrical properties, as well as subband tail formation-quantified by the Urbach energy (EU)-as a function of the sputtering oxygen partial pressure.more » We obtain an EU as low as 128 meV for films with the highest Hall mobility of 60 cm2/Vs. When comparing the performance of a-IZO films with indium tin oxide (ITO) and hydrogenated indium oxide (IO:H), we find that IO:H (115 cm2/Vs) exhibits a similar EU of 130 meV, while ITO (25 cm2/Vs) presents a much larger EU of up to 270 meV. The high film quality, indicated by the low EU, the high mobility, and low free carrier absorption of the developed a-IZO electrodes, result in a significant current improvement, achieving conversion efficiencies over 21.5%, outperforming those with standard ITO.« less

  8. NMR study of ortho-molecular hydrogen in hydrogenated amorphous silicon

    SciTech Connect (OSTI)

    Su, T.; Taylor, P.C.; Chen, S.; Crandall, R.S.; Mahan, A.H.

    1999-07-01

    A Jeener-Broekaert three-pulse sequence is used to investigate ortho-molecular hydrogen (o-H{sub 2}) in device quality amorphous silicon films prepared by plasma enhanced chemical vapor deposition (PECVD) and hot wire CVD (HWCVD). For the PECVD sample, the concentration of hydrogen moleculars is {approximately}11% of the total hydrogen concentration, one order of magnitude larger than that inferred from spin-lattice relaxation time measurements ({approximately}1%). Hence, most of the hydrogen molecules do not serve as effective relaxation centers. For HWCVD samples with {approximately}3 to 4% hydrogen and very low void densities, the concentrations of hydrogen molecules are {approximately}1% of the total hydrogen concentration. In these samples, spin-lattice relaxation measurements for bonded hydrogen indicate that the concentration of hydrogen molecules that contribute to spin-lattice relaxation is at most 0.1% of the total hydrogen concentration. Spin-lattice relaxation time (T{sub 1}) measurements of ortho-molecular hydrogen indicate two very different T{sub 1}'s. The longer T{sub 1} is {approximately} 0.6 s, possibly due to an electric quadrupole-quadrupole (EQQ) interaction between o-H{sub 2} molecules and, the shorter T{sub 1} is {approximately} 3 ms, very close to that calculated for a two-phonon Raman process for rotating o-H{sub 2}.

  9. Field collapse due to band-tail charge in amorphous silicon solar cells

    SciTech Connect (OSTI)

    Wang, Qi; Crandall, R.S.; Schiff, E.A.

    1996-05-01

    It is common for the fill factor to decrease with increasing illumination intensity in hydrogenated amorphous silicon solar cells. This is especially critical for thicker solar cells, because the decrease is more severe than in thinner cells. Usually, the fill factor under uniformly absorbed red light changes much more than under strongly absorbed blue light. The cause of this is usually assumed to arise from space charge trapped in deep defect states. The authors model this behavior of solar cells using the Analysis of Microelectronic and Photonic Structures (AMPS) simulation program. The simulation shows that the decrease in fill factor is caused by photogenerated space charge trapped in the band-tail states rather than in defects. This charge screens the applied field, reducing the internal field. Owing to its lower drift mobility, the space charge due to holes exceeds that due to electrons and is the main cause of the field screening. The space charge in midgap states is small compared with that in the tails and can be ignored under normal solar-cell operating conditions. Experimentally, the authors measured the photocapacitance as a means to probe the collapsed field. They also explored the light intensity dependence of photocapacitance and explain the decrease of FF with the increasing light intensity.

  10. Optically activated sub-millimeter dielectric relaxation in amorphous thin film silicon at room temperature

    SciTech Connect (OSTI)

    Rahman, Rezwanur; Ohno, Tim R.; Taylor, P. C.; Scales, John A.

    2014-05-05

    Knowing the frequency-dependent photo-induced complex conductivity of thin films is useful in the design of photovoltaics and other semi-conductor devices. For example, annealing in the far-infrared could in principle be tailored to the specific dielectric properties of a particular sample. The frequency dependence of the conductivity (whether dark or photo-induced) also gives insight into the effective dimensionality of thin films (via the phonon density of states) as well as the presence (or absence) of free carriers, dopants, defects, etc. Ultimately, our goal is to make low-noise, phase-sensitive room temperature measurements of the frequency-dependent conductivity of thin films from microwave frequencies into the far-infrared; covering, the frequency range from ionic and dipole relaxation to atomic and electronic processes. To this end, we have developed a high-Q (quality factor) open cavity resonator capable of resolving the complex conductivity of sub-micron films in the range of 100350?GHz (0.10.35 THz, or 0.41?meV). In this paper, we use a low-power green laser to excite bound charges in high-resistivity amorphous silicon thin film. Even at room temperature, we can resolve both the dark conductivity and photo-induced changes associated with dielectric relaxation and possibly some small portion of free carriers.

  11. Efficient nanorod-based amorphous silicon solar cells with advanced light trapping

    SciTech Connect (OSTI)

    Kuang, Y.; Lare, M. C. van; Polman, A.; Veldhuizen, L. W.; Schropp, R. E. I.; Rath, J. K.

    2015-11-14

    We present a simple, low-cost, and scalable approach for the fabrication of efficient nanorod-based solar cells. Templates with arrays of self-assembled ZnO nanorods with tunable morphology are synthesized by chemical bath deposition using a low process temperature at 80 °C. The nanorod templates are conformally coated with hydrogenated amorphous silicon light absorber layers of 100 nm and 200 nm thickness. An initial efficiency of up to 9.0% is achieved for the optimized design. External quantum efficiency measurements on the nanorod cells show a substantial photocurrent enhancement both in the red and the blue parts of the solar spectrum. Key insights in the light trapping mechanisms in these arrays are obtained via a combination of three-dimensional finite-difference time-domain simulations, optical absorption, and external quantum efficiency measurements. Front surface patterns enhance the light incoupling in the blue, while rear side patterns lead to enhanced light trapping in the red. The red response in the nanorod cells is limited by absorption in the patterned Ag back contact. With these findings, we develop and experimentally realize a further advanced design with patterned front and back sides while keeping the Ag reflector flat, showing significantly enhanced scattering from the back reflector with reduced parasitic absorption in the Ag and thus higher photocurrent generation. Many of the findings in this work can serve to provide insights for further optimization of nanostructures for thin-film solar cells in a broad range of materials.

  12. Low-temperature high-mobility amorphous IZO for silicon heterojunction solar cells

    SciTech Connect (OSTI)

    Morales-Masis, Monica; Martin De Nicolas, Silvia; Holovsky, Jakub; De Wolf, Stefaan; Ballif, Christophe

    2015-07-13

    Parasitic absorption in the transparent conductive oxide (TCO) front electrode is one of the limitations of silicon heterojunction (SHJ) solar cells efficiency. To avoid such absorption while retaining high conductivity, TCOs with high electron mobility are preferred over those with high carrier density. Here, we demonstrate improved SHJ solar cell efficiencies by applying high-mobility amorphous indium zinc oxide (a-IZO) as the front TCO. We sputtered a-IZO at low substrate temperature and low power density and investigated the optical and electrical properties, as well as subband tail formation-quantified by the Urbach energy (EU)-as a function of the sputtering oxygen partial pressure. We obtain an EU as low as 128 meV for films with the highest Hall mobility of 60 cm2/Vs. When comparing the performance of a-IZO films with indium tin oxide (ITO) and hydrogenated indium oxide (IO:H), we find that IO:H (115 cm2/Vs) exhibits a similar EU of 130 meV, while ITO (25 cm2/Vs) presents a much larger EU of up to 270 meV. The high film quality, indicated by the low EU, the high mobility, and low free carrier absorption of the developed a-IZO electrodes, result in a significant current improvement, achieving conversion efficiencies over 21.5%, outperforming those with standard ITO.

  13. Structural properties of a-Si films and their effect on aluminum induced crystallization

    SciTech Connect (OSTI)

    Tankut, Aydin; Ozkol, Engin; Karaman, Mehmet; Turan, Rasit; Canli, Sedat

    2015-10-15

    In this paper, we report the influence of the structural properties of amorphous silicon (a-Si) on its subsequent crystallization behavior via the aluminum induced crystallization (AIC) method. Two distinct a-Si deposition techniques, electron beam evaporation and plasma enhanced chemical vapor deposition (PECVD), are compared for their effect on the overall AIC kinetics as well as the properties of the final poly-crystalline (poly-Si) silicon film. Raman and FTIR spectroscopy results indicate that the PECVD grown a-Si films has higher intermediate-range order, which is enhanced for increased hydrogen dilution during deposition. With increasing intermediate-range order of the a-Si, the rate of AIC is diminished, leading larger poly-Si grain size.

  14. Calibration of an amorphous-silicon flat panel portal imager for exit-beam dosimetry

    SciTech Connect (OSTI)

    Chen, Josephine; Chuang, Cynthia F.; Morin, Olivier; Aubin, Michele; Pouliot, Jean

    2006-03-15

    Amorphous-silicon flat panel detectors are currently used to acquire digital portal images with excellent image quality for patient alignment before external beam radiation therapy. As a first step towards interpreting portal images acquired during treatment in terms of the actual dose delivered to the patient, a calibration method is developed to convert flat panel portal images to the equivalent water dose deposited in the detector plane and at a depth of 1.5 cm. The method is based on empirical convolution models of dose deposition in the flat panel detector and in water. A series of calibration experiments comparing the response of the flat panel imager and ion chamber measurements of dose in water determines the model parameters. Kernels derived from field size measurements account for the differences in the production and detection of scattered radiation in the two systems. The dissimilar response as a function of beam energy spectrum is characterized from measurements performed at various off-axis positions and for increasing attenuator thickness in the beam. The flat panel pixel inhomogeneity is corrected by comparing a large open field image with profiles measured in water. To verify the accuracy of the calibration method, calibrated flat panel profiles were compared with measured dose profiles for fields delivered through solid water slabs, a solid water phantom containing an air cavity, and an anthropomorphic head phantom. Open rectangular fields of various sizes and locations as well as a multileaf collimator-shaped field were delivered. For all but the smallest field centered about the central axis, the calibrated flat panel profiles matched the measured dose profiles with little or no systematic deviation and approximately 3% (two standard deviations) accuracy for the in-field region. The calibrated flat panel profiles for fields located off the central axis showed a small -1.7% systematic deviation from the measured profiles for the in-field region

  15. Facile synthesis of highly stable a-Si by ion implantation of low-keV H isotopes

    SciTech Connect (OSTI)

    Moutanabbir, O.; Scholz, R.; Goesele, U.; Terreault, B.

    2009-06-15

    It is experimentally shown that silicon is 'easily' amorphized by low-keV H ions at the relatively high temperature of 150 K and for an ion fluence equivalent to <1 DPA (displacement per atom). The a-Si layer is much more stable against recrystallization than a-Si produced by other ions and more stable against chemical modification than c-Si that is H-implanted at room temperature. These results are unexplained by the current atomic collision theory, including molecular-dynamics simulations, but they demonstrate the stabilizing effect of dangling bond passivation by H atoms in postulated, metastable, amorphous droplets.

  16. Silicon Solar Cells with Front Hetero-Contact and Aluminum Alloy Back Junction: Preprint

    SciTech Connect (OSTI)

    Yuan, H.-C.; Page, M. R.; Iwaniczko, E.; Xu, Y.; Roybal, L.; Wang, Q.; Branz, H. M.; Meier, D. L.

    2008-05-01

    We prototype an alternative n-type monocrystalline silicon (c-Si) solar cell structure that utilizes an n/i-type hydrogenated amorphous silicon (a-Si:H) front hetero-contact and a back p-n junction formed by alloying aluminum (Al) with the n-type Si wafer.

  17. New Approaches for Passivation of Crystalline and Amorphous Silicon: Cooperative Research and Development Final Report, CRADA Number CRD-09-351

    SciTech Connect (OSTI)

    Sopori, B.

    2012-09-01

    New approaches of passivating crystalline, multicrystalline, and amorphous silicon will be explored. These will include the use of aqueous solution of KCN and a proprietary composition formulated by Mallinckrodt Baker, Inc. The surface passivation will be compared with that provided by an iodine-ethanol solution, and bulk passivation will be compared with that of H-passivation obtained by silicon nitride, in a fire-through process.

  18. Development of high, stable-efficiency triple-junction a-Si alloy solar cells. Annual technical progress report, October 1995--October 1996

    SciTech Connect (OSTI)

    Deng, X.; Izu, M.; Jones, S.J.; Kopf, R.

    1997-04-01

    The overall objective of this amorphous silicon research program is to develop high efficiency a-Si solar cells and to develop and improve processes for large area deposition of a-Si solar cells and modules. The knowledge obtained and technologies demonstrated in this program will be incorporated into ECD`s continuous roll-to-roll deposition process to further enhance its photovoltaic manufacturing technology.

  19. Diversity in short-to-intermediate range order in pure forms of amorphous silicon generated by a variety of experimental and modeling techniques

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Holmstrom, Eero; Haberl, Bianca; Pakarinen, Olli H; Nordlund, Kai; Djurabekova, Flyura; Arenal, Raul; Williams, James S.; Bradby, Jodie E.; Petersen, Timothy C.; Liu, Amelia

    2016-01-01

    Variability in the short-to-intermediate range order of pure amorphous silicon prepared by different experimental and computational techniques is probed by measuring mass density, atomic coordination, bond-angle deviation, and dihedral angle deviation. It is found that there is significant variability in order parameters at these length scales in this archetypal covalently bonded, monoatomic system. This diversity strongly reflects preparation technique and thermal history in both experimental and simulated systems. Experiment and simulation do not fully quantitatively agree, partly due to differences in the way parameters are accessed. However, qualitative agreement in the trends is identified. Relaxed forms of amorphous silicon closelymore » resemble continuous random networks generated by a hybrid method of bond-switching Monte Carlo and molecular dynamics simulation. As-prepared ion implanted amorphous silicon can be adequately modeled using a structure generated from amorphization via ion bombardement using energetic recoils. Preparation methods which narrowly avoid crystallization such as experimental pressure-induced amorphization or simulated melt-quenching result in inhomogeneous structures that contain regions with significant variations in atomic ordering. Ad hoc simulated structures containing small (1 nm) diamond cubic crystal inclusions were found to possess relatively high bond-angle deviations and low dihedral angle deviations, a trend that could not be reconciled with any experimental material.« less

  20. Diversity in short-to-intermediate range order in pure forms of amorphous silicon generated by a variety of experimental and modeling techniques

    SciTech Connect (OSTI)

    Holmstrom, Eero; Haberl, Bianca; Pakarinen, Olli H; Nordlund, Kai; Djurabekova, Flyura; Arenal, Raul; Williams, James S.; Bradby, Jodie E.; Petersen, Timothy C.; Liu, Amelia

    2016-01-01

    Variability in the short-to-intermediate range order of pure amorphous silicon prepared by different experimental and computational techniques is probed by measuring mass density, atomic coordination, bond-angle deviation, and dihedral angle deviation. It is found that there is significant variability in order parameters at these length scales in this archetypal covalently bonded, monoatomic system. This diversity strongly reflects preparation technique and thermal history in both experimental and simulated systems. Experiment and simulation do not fully quantitatively agree, partly due to differences in the way parameters are accessed. However, qualitative agreement in the trends is identified. Relaxed forms of amorphous silicon closely resemble continuous random networks generated by a hybrid method of bond-switching Monte Carlo and molecular dynamics simulation. As-prepared ion implanted amorphous silicon can be adequately modeled using a structure generated from amorphization via ion bombardement using energetic recoils. Preparation methods which narrowly avoid crystallization such as experimental pressure-induced amorphization or simulated melt-quenching result in inhomogeneous structures that contain regions with significant variations in atomic ordering. Ad hoc simulated structures containing small (1 nm) diamond cubic crystal inclusions were found to possess relatively high bond-angle deviations and low dihedral angle deviations, a trend that could not be reconciled with any experimental material.

  1. Research on stable, high-efficiency amorphous silicon multijunction modules. Semiannual subcontract report, 1 March 1993--30 November 1993

    SciTech Connect (OSTI)

    Guha, S.

    1994-03-01

    This report describes the progress made during the first half of Phase III of the R&D program to obtain high-efficiency amorphous silicon alloy multijunction modules. The highlight of the work includes (1) demonstration of the world`s highest initial module efficiency (area of 0.09 m{sup 2}) of 11.4% as confirmed by NREL, and (2) demonstration of stable module efficiency of 9.5% after 1-sun light soaking for 1000 h at 50{degrees}C. In addition, fundamental studies were carried out to improve material properties of the component cells of the multijunction structure and to understand the optical losses associated with the back reflector.

  2. High-Efficiency Amorphous Silicon and Nanocrystalline Silicon Based Solar Cells and Modules: Annual Technical Progress Report, 30 January 2006 - 29 January 29, 2007

    SciTech Connect (OSTI)

    Guha, S.; Yang, J.

    2007-07-01

    United Solar used a-Si:H/a-SiGe:H/a-SiGe:H in two manufacturing plants and improved solar efficiency and reduced manufacturing cost by new deposition methods, optimized deposition parameters, and new materials and cell structures.

  3. Observation of slow dangling-bond relaxation in [ital p]-type hydrogenated amorphous silicon

    SciTech Connect (OSTI)

    Carlen, M.W.; Xu, Y.; Crandall, R.S. )

    1995-01-15

    Using junction-capacitance methods, we study the thermal charge emission of holes trapped in the dangling-bond defect [ital D] of [ital p]-type [ital a]-Si:H. Over a significant temperature range, we find a linear temperature-independent relation between emission time and the residence time of the hole on the [ital D] defect. We attribute this characteristic to a structural-relaxation process that is slow in disordered materials.

  4. Doped silicon nanocrystals from organic dopant precursor by a SiCl{sub 4}-based high frequency nonthermal plasma

    SciTech Connect (OSTI)

    Zhou, Shu; Ding, Yi; Nozaki, Tomohiro; Pi, Xiaodong

    2014-11-03

    Doped silicon nanocrystals (Si NCs) are of great interest in demanding low-cost nanodevices because of the abundance and nontoxicity of Si. Here, we demonstrate a cost-effective gas phase approach to synthesize phosphorous (P)-doped Si NCs in which the precursors used, i.e., SiCl{sub 4}, trimethyl phosphite (TMP), are both safe and economical. It is found that the TMP-enabled P-doping does not change the crystalline structure of Si NCs. The surface of P-doped Si NCs is terminated by both Cl and H. The Si–H bond density at the surface of P-doped Si NCs is found to be much higher than that of undoped Si NCs. The X-ray photoelectron spectroscopy and electron spin resonance results indicate that P atoms are doped into the substitutional sites of the Si-NC core and electrically active in Si NCs. Unintentional impurities, such as carbon contained in TMP, are not introduced into Si NCs.

  5. Deposition of device quality, low hydrogen content, hydrogenated amorphous silicon at high deposition rates

    DOE Patents [OSTI]

    Mahan, Archie Harvin; Molenbroek, Edith C.; Gallagher, Alan C.; Nelson, Brent P.; Iwaniczko, Eugene; Xu, Yueqin

    2002-01-01

    A method of fabricating device quality, thin-film a-Si:H for use as semiconductor material in photovoltaic and other devices, comprising in any order; positioning a substrate in a vacuum chamber adjacent a plurality of heatable filaments with a spacing distance L between the substrate and the filaments; heating the filaments to a temperature that is high enough to obtain complete decomposition of silicohydride molecules that impinge said filaments into Si and H atomic species; providing a flow of silicohydride gas, or a mixture of silicohydride gas containing Si and H, in said vacuum chamber while maintaining a pressure P of said gas in said chamber, which, in combination with said spacing distance L, provides a P.times.L product in a range of 10-300 mT-cm to ensure that most of the Si atomic species react with silicohydride molecules in the gas before reaching the substrate, to thereby grow a a-Si:H film at a rate of at least 50 .ANG./sec.; and maintaining the substrate at a temperature that balances out-diffusion of H from the growing a-Si:H film with time needed for radical species containing Si and H to migrate to preferred bonding sites.

  6. ENHANCED GROWTH RATE AND SILANE UTILIZATION IN AMORPHOUS SILICON AND NANOCRYSTALLINE-SILICON SOLAR CELL DEPOSITION VIA GAS PHASE ADDITIVES

    SciTech Connect (OSTI)

    Ridgeway, R.G.; Hegedus, S.S.; Podraza, N.J.

    2012-08-31

    Air Products set out to investigate the impact of additives on the deposition rate of both µCSi and αSi-H films. One criterion for additives was that they could be used in conventional PECVD processing, which would require sufficient vapor pressure to deliver material to the process chamber at the required flow rates. The flow rate required would depend on the size of the substrate onto which silicon films were being deposited, potentially ranging from 200 mm diameter wafers to the 5.7 m2 glass substrates used in GEN 8.5 flat-panel display tools. In choosing higher-order silanes, both disilane and trisilane had sufficient vapor pressure to withdraw gas at the required flow rates of up to 120 sccm. This report presents results obtained from testing at Air Products’ electronic technology laboratories, located in Allentown, PA, which focused on developing processes on a commercial IC reactor using silane and mixtures of silane plus additives. These processes were deployed to compare deposition rates and film properties with and without additives, with a goal of maximizing the deposition rate while maintaining or improving film properties.

  7. An investigation of hydrogenized amorphous Si structures with Doppler broadening positron annihilation techniques

    SciTech Connect (OSTI)

    Petkov, M.P.; Marek, T.; Asoka-Kumar, P.; Lynn, K.G.; Crandall, R.S.; Mahan, A.H.

    1998-07-01

    In this letter, we examine the feasibility of applying positron annihilation spectroscopy to the study of hydrogenized amorphous silicon (a-Si:H)-based structures produced by chemical vapor deposition techniques. The positron probe, sensitive to open volume formations, is used to characterize neutral and negatively charged silicon dangling bonds, typical for undoped and {ital n}-doped a-Si:H, respectively. Using depth profiling along the growth direction a difference was observed in the electronic environment of these defects, which enables their identification in a p-i-n device. {copyright} {ital 1998 American Institute of Physics.}

  8. Impact of solid-phase crystallization of amorphous silicon on the chemical structure of the buried Si/ZnO thin film solar cell interface

    SciTech Connect (OSTI)

    Bar, M.; Wimmer, M.; Wilks, R. G.; Roczen, M.; Gerlach, D.; Ruske, F.; Lips, K.; Rech, B.; Weinhardt, L.; Blum, M.; Pookpanratana, S.; Krause, S.; Zhang, Y.; Heske, C.; Yang, W.; Denlinger, J. D.

    2010-04-30

    The chemical interface structure between phosphorus-doped hydrogenated amorphous silicon and aluminum-doped zinc oxide thin films is investigated with soft x-ray emission spectroscopy (XES) before and after solid-phase crystallization (SPC) at 600C. In addition to the expected SPC-induced phase transition from amorphous to polycrystalline silicon, our XES data indicates a pronounced chemical interaction at the buried Si/ZnO interface. In particular, we find an SPC-enhanced formation of Si-O bonds and the accumulation of Zn in close proximity to the interface. For an assumed closed and homogeneous SiO2 interlayer, an effective thickness of (5+2)nm after SPC could be estimated.

  9. Microstructure of amorphous-silicon-based solar cell materials by small-angle x-ray scattering. Annual subcontract report, 6 April 1994--5 April 1995

    SciTech Connect (OSTI)

    Williamson, D.L.

    1995-08-01

    The general objective of this research is to provide detailed microstructural information on the amorphous-silicon-based, thin-film materials under development for improved multijunction solar cells. The experimental technique used is small-angle x-ray scattering (SAXS) providing microstructural data on microvoid fractions, sizes, shapes, and their preferred orientations. Other microstructural features such as alloy segregation, hydrogen-rich clusters and alloy short-range order are probed.

  10. Continuous roll-to-roll amorphous silicon photovoltaic manufacturing technology. Semiannual subcontract report, 1 April 1993--30 September 1993

    SciTech Connect (OSTI)

    Izu, M.

    1994-06-01

    This report describes work for this reporting period under a 3-year program to advance Energy Conversion Device`s (ECD) roll-to-roll, triple-junction photovoltaic (PV) manufacturing technologies, to reduce the module production costs, to increase the stabilized module performance, and to expand commercial production capacity utilizing ECD technology. The specific 3-year goal is to develop advanced large-scale manufacturing technology incorporating ECD`s earlier research advances with the capability of producing modules with stable 11% efficiency at a cost of approximately $1.00 per peak watt. Major accomplishments during this reporting period include (1) the design, construction. amd testomg of a continuous roll-to-roll multipurpose amorphous silicon alloy solar cell deposition machine that incorporates improvements necessary to obtain higher efficiency solar cells; (2) development of a photothermal deflection spectroscopy (PDS) technique for evaluating back-reflector systems; (3) the development of an improved textured Ag/ZnO back-reflector system demonstrating 25% gain in J{sub sc} over previous textured Al back-reflector systems; and (4) the design of a serpentine web continuous roll-to-roll deposition chamber.

  11. High-Efficiency Amorphous Silicon and Nanocrystalline Silicon-Based Solar Cells and Modules: Final Technical Progress Report, 30 January 2006 - 29 January 2008

    SciTech Connect (OSTI)

    Guha, S.; Yang, J.

    2008-05-01

    United Solar Ovonic successfully used its spectrum-splitting a-Si:H/a-SiGe:H/a-SiGe:H triple-junction structure in their manufacturing plants, achieving a manufacturing capacity of 118 MW in 2007, and set up a very aggressive expansion plan to achieve grid parity.

  12. Thermal stability of photovoltaic a-Si:H determined by neutron reflectometry

    SciTech Connect (OSTI)

    Qviller, A. J. Haug, H.; You, C. C.; Hasle, I. M.; Marstein, E. S.; Frommen, C.; Hauback, B. C.; Dennison, A. J. C.; Vorobiev, A.; streng, E.; Fjellvg, H.; Hjrvarsson, B.

    2014-12-08

    Neutron and X-ray reflectometry were used to determine the layer structure and hydrogen content of thin films of amorphous silicon (a-Si:H) deposited onto crystalline silicon (Si) wafers for surface passivation in solar cells. The combination of these two reflectometry techniques is well suited for non-destructive probing of the structure of a-Si:H due to being able to probe buried interfaces and having sub-nanometer resolution. Neutron reflectometry is also unique in its ability to allow determination of density gradients of light elements such as hydrogen (H). The neutron scattering contrast between Si and H is strong, making it possible to determine the H concentration in the deposited a-Si:H. In order to correlate the surface passivation properties supplied by the a-Si:H thin films, as quantified by obtainable effective minority carrier lifetime, photoconductance measurements were also performed. It is shown that the minority carrier lifetime falls sharply when H has been desorbed from a-Si:H by annealing.

  13. Comparative life-cycle energy payback analysis of multi-junction a-SiGe and nanocrystalline/a-Si modules

    SciTech Connect (OSTI)

    Fthenakis, V.; Kim, H.

    2010-07-15

    Despite the publicity of nanotechnologies in high tech industries including the photovoltaic sector, their life-cycle energy use and related environmental impacts are understood only to a limited degree as their production is mostly immature. We investigated the life-cycle energy implications of amorphous silicon (a-Si) PV designs using a nanocrystalline silicon (nc-Si) bottom layer in the context of a comparative, prospective life-cycle analysis framework. Three R and D options using nc-Si bottom layer were evaluated and compared to the current triple-junction a-Si design, i.e., a-Si/a-SiGe/a-SiGe. The life-cycle energy demand to deposit nc-Si was estimated from parametric analyses of film thickness, deposition rate, precursor gas usage, and power for generating gas plasma. We found that extended deposition time and increased gas usages associated to the relatively high thickness of nc-Si lead to a larger primary energy demand for the nc-Si bottom layer designs, than the current triple-junction a-Si. Assuming an 8% conversion efficiency, the energy payback time of those R and D designs will be 0.7-0.9 years, close to that of currently commercial triple-junction a-Si design, 0.8 years. Future scenario analyses show that if nc-Si film is deposited at a higher rate (i.e., 2-3 nm/s), and at the same time the conversion efficiency reaches 10%, the energy-payback time could drop by 30%.

  14. Fluorination of amorphous thin-film materials with xenon fluoride

    DOE Patents [OSTI]

    Weil, R.B.

    1987-05-01

    A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

  15. Fluorination of amorphous thin-film materials with xenon fluoride

    DOE Patents [OSTI]

    Weil, Raoul B. (Haifa, IL)

    1988-01-01

    A method is disclosed for producing fluorine-containing amorphous semiconductor material, preferably comprising amorphous silicon. The method includes depositing amorphous thin-film material onto a substrate while introducing xenon fluoride during the film deposition process.

  16. Deposition of device quality, low hydrogen content, hydrogenated amorphous silicon at high deposition rates with increased stability using the hot wire filament technique

    DOE Patents [OSTI]

    Molenbroek, Edith C.; Mahan, Archie Harvin; Gallagher, Alan C.

    2000-09-26

    A method or producing hydrogenated amorphous silicon on a substrate, comprising the steps of: positioning the substrate in a deposition chamber at a distance of about 0.5 to 3.0 cm from a heatable filament in the deposition chamber; maintaining a pressure in said deposition chamber in the range of about 10 to 100 millitorr and pressure times substrate-filament spacing in the range of about 10 to 100 millitorr-cm, heating the filament to a temperature in the range of about 1,500 to 2,000.degree. C., and heating the substrate to a surface temperature in the range of about 280 to 475.degree. C.; and flowing silicohydride gas into the deposition chamber with said heated filament, decomposing said silicohydride gas into silicon and hydrogen atomic species and allowing products of gas reactions between said atomic species and the silicohydride gas to migrate to and deposit on said substrate while adjusting and maintaining said pressure times substrate-filament spacing in said deposition chamber at a value in said 10 to 100 millitorr range to produce statistically about 3 to 50 atomic collisions between the silicon and hydrogen atomic species migrating to said substrate and undecomposed molecules of the silane or other silicohydride gas in the deposition chamber.

  17. Growth kinetics and compositional analysis of silicon rich a-SiN{sub x}:H film: A soft x-ray reflectivity study

    SciTech Connect (OSTI)

    Singh, Sarab Preet; Srivastava, P.; Modi, Mohammed H.

    2010-10-11

    We report soft x-ray reflectivity measurements near the Si L{sub 2,3} absorption edge for Si-rich silicon nitride thin film obtained by Hg-sensitized photochemical vapor deposition. We demonstrate that the precise analysis of optical index profile derived over extended energy region gives compositional details of the film. This nondestructive approach is used in Si-rich silicon nitride film to reveal buried Si-rich interfacial layer. Further, the combined study of soft x-ray reflectivity and optical density obtained from the reflectivity fitting at various photon energies provide a qualitative estimation of the film composition and its growth.

  18. Buried oxide layer in silicon

    DOE Patents [OSTI]

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2001-01-01

    A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

  19. Junction Transport in Epitaxial Film Silicon Heterojunction Solar Cells

    SciTech Connect (OSTI)

    Young, D. L.; Li, J. V.; Teplin, C. W.; Stradins, P.; Branz, H. M.

    2011-01-01

    We report our progress toward low-temperature HWCVD epitaxial film silicon solar cells on inexpensive seed layers, with a focus on the junction transport physics exhibited by our devices. Heterojunctions of i/p hydrogenated amorphous Si (a-Si) on our n-type epitaxial crystal Si on n{sup ++} Si wafers show space-charge-region recombination, tunneling or diffusive transport depending on both epitaxial Si quality and the applied forward voltage.

  20. Junction Transport in Epitaxial Film Silicon Heterojunction Solar Cells: Preprint

    SciTech Connect (OSTI)

    Young, D. L.; Li, J. V.; Teplin, C. W.; Stradins, P.; Branz, H. M.

    2011-07-01

    We report our progress toward low-temperature HWCVD epitaxial film silicon solar cells on inexpensive seed layers, with a focus on the junction transport physics exhibited by our devices. Heterojunctions of i/p hydrogenated amorphous Si (a-Si) on our n-type epitaxial crystal Si on n++ Si wafers show space-charge-region recombination, tunneling or diffusive transport depending on both epitaxial Si quality and the applied forward voltage.

  1. Performance Test of Amorphous Silicon Modules in Different Climates - Year Four: Progress in Understanding Exposure History Stabilization Effects; Preprint

    SciTech Connect (OSTI)

    Ruther, R.; Montenegro, A. A.; del Cueto, J.; Rummel, S.; Anderberg, A.; von Roedern, B.; Tamizh-Mani, G.

    2008-05-01

    The four-year experiment involved three identical sets of thin-film a-Si modules from various manufacturers deployed outdoors simultaneously in three sites with distinct climates. Each PV module set spent a one-year period at each site before a final period at the original site where it was first deployed.

  2. High Efficiency Amorphous and Microcrystalline Silicon Based Double-Junction Solar Cells made with Very-High-Frequency Glow Discharge

    SciTech Connect (OSTI)

    Banerjee, Arindam

    2004-10-20

    We have achieved a total-area initial efficiency of 11.47% (active-area efficiency of 12.33%) on a-Si:H/?c-Si:H double-junction structure, where the intrinsic layer bottom cell was made in 50 minutes. On another device in which the bottom cell was made in 30 min, we achieved initial total-area efficiency of 10.58% (active-efficiency of 11.35%). We have shown that the phenomenon of ambient degradation of both ?c-Si:H single-junction and a-Si:H/?c-Si:H double-junction cells can be attributed to impurity diffusion after deposition. Optimization of the plasma parameters led to alleviation of the ambient degradation. Appropriate current matching between the top and bottom component cells has resulted in a stable total-area efficiency of 9.7% (active-area efficiency of 10.42%) on an a-Si:H/?c-Si:H double-junction solar cell in which the deposition time for the ?c-Si:H intrinsic layer deposition was of 30 min.

  3. Near single-crystalline, high-carrier-mobility silicon thin film on a polycrystalline/amorphous substrate

    DOE Patents [OSTI]

    Findikoglu, Alp T.; Jia, Quanxi; Arendt, Paul N.; Matias, Vladimir; Choi, Woong

    2009-10-27

    A template article including a base substrate including: (i) a base material selected from the group consisting of polycrystalline substrates and amorphous substrates, and (ii) at least one layer of a differing material upon the surface of the base material; and, a buffer material layer upon the base substrate, the buffer material layer characterized by: (a) low chemical reactivity with the base substrate, (b) stability at temperatures up to at least about 800.degree. C. under low vacuum conditions, and (c) a lattice crystal structure adapted for subsequent deposition of a semiconductor material; is provided, together with a semiconductor article including a base substrate including: (i) a base material selected from the group consisting of polycrystalline substrates and amorphous substrates, and (ii) at least one layer of a differing material upon the surface of the base material; and, a buffer material layer upon the base substrate, the buffer material layer characterized by: (a) low chemical reactivity with the base substrate, (b) stability at temperatures up to at least about 800.degree. C. under low vacuum conditions, and (c) a lattice crystal structure adapted for subsequent deposition of a semiconductor material, and, a top-layer of semiconductor material upon the buffer material layer.

  4. Amorphous semiconductor solar cell

    DOE Patents [OSTI]

    Dalal, Vikram L.

    1981-01-01

    A solar cell comprising a back electrical contact, amorphous silicon semiconductor base and junction layers and a top electrical contact includes in its manufacture the step of heat treating the physical junction between the base layer and junction layer to diffuse the dopant species at the physical junction into the base layer.

  5. Stability of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/a-SiN{sub x}:H stacks for surface passivation of crystalline silicon

    SciTech Connect (OSTI)

    Dingemans, G.; Hoex, B.; Sanden, M. C. M. van de; Kessels, W. M. M.; Engelhart, P.; Seguin, R.; Einsele, F.

    2009-12-01

    The thermal and ultraviolet (UV) stability of crystalline silicon (c-Si) surface passivation provided by atomic layer deposited Al{sub 2}O{sub 3} was compared with results for thermal SiO{sub 2}. For Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/a-SiN{sub x}:H stacks on 2 OMEGA cm n-type c-Si, ultralow surface recombination velocities of S{sub eff}<3 cm/s were obtained and the passivation proved sufficiently stable (S{sub eff}<14 cm/s) against a high temperature 'firing' process (>800 deg. C) used for screen printed c-Si solar cells. Effusion measurements revealed the loss of hydrogen and oxygen during firing through the detection of H{sub 2} and H{sub 2}O. Al{sub 2}O{sub 3} also demonstrated UV stability with the surface passivation improving during UV irradiation.

  6. High Efficiency and High Rate Deposited Amorphous Silicon-Based Solar Cells: Final Technical Report, 1 September 2001--6 March 2005

    SciTech Connect (OSTI)

    Deng, X.

    2006-01-01

    The objectives for the University of Toledo are to: (1) establish a transferable knowledge and technology base for fabricating high-efficiency triple-junction a-Si-based solar cells, and (2) develop high-rate deposition techniques for the growing a-Si-based and related alloys, including poly-Si, c-Si, a-SiGe, and a-Si films and photovoltaic devices with these materials.

  7. Characterization of the protonic distribution and environment in amorphous silicon-hydrogen alloys using proton NMR and ESR

    SciTech Connect (OSTI)

    Jeffrey, F.R.; Lowry, M.E.; Garcia, M.L.S.; Barnes, R.G.; Torgeson, D.E.

    1981-06-01

    We present magnetic resonance data from a series of a-Si(H) samples deposited under varied hydrogen partial pressures. This parameter has been shown to be directly related to the sample-wide average proton density. The other sputtering parameters were maintained such that no dihydride bonding (as determined by the 890 cm/sup -1/ir bending mode) is present. Measurements presented are the NMR absorption spectrum (from the Fourier transform of the free induction decay), relaxation time T/sub 1/, and ESR absorption. The NMR absorption spectrum identifies two distinct forms of H incorporation. One is a tightly clustered form, such as H bonded on the inner surface of a microvoid of maximum dimension 5A, while the other is a randomly distributed phase with local H density of 3.5 x 10/sup 21/ cm/sup -3/. The distributed phase H density is independent of the sample-wide average, indicating a fixed composition phase which occupies a larger percentage of the sample as H pressure is increased during deposition. This phase appears to extend to a maximum of 88% of the sample. The protonic spin-lattice relaxation time (T/sub 1/) measures the coupling of the spin system to its enviroment, ''the lattice''. For the series of samples, we find that T/sub 1/ first increases from 2.8 s to 44.8 s with increasing H content and then decreases to 8.1 s as H density is further increased. In an effort to understand this unusual relaxation behavior, we have made temperature dependant T/sub 1/ and ESR measurements. Utilizing these results, the protonic relaxation mechanism is discussed in terms ''disorder mode'' and electronic state models.

  8. Strongly enhanced tunable photoluminescence in polymorphous silicon carbon thin films via excitation-transfer mechanism

    SciTech Connect (OSTI)

    Wang Junzhuan; Suendo, V.; Abramov, A.; Yu Linwei; Roca i Cabarrocas, Pere

    2010-11-29

    Here, we investigate the enhanced tunable photoluminescence (PL) of hydrogenated polymorphous silicon carbon (pm-Si{sub 1-x}C{sub x}:H) thin films fabricated in a plasma enhanced chemical vapor deposition system. The silicon nanocrystal (nc-Si) inclusions are formed during gas-phase nucleation and incorporated in the hydrogenated amorphous silicon carbon (a-SiC:H) matrix. The nc-Si provides high-quality recombination centers for the photogenerated carriers in the pm-Si{sub 1-x}C{sub x}:H material, while the a-SiC:H matrix plays a role of sensitizer. We elucidate and provide experimental evidence for this excitation-transfer mechanism. Strongly enhanced PL performance can be achieved by effective matrix passivation that favors a diffusion-driven carrier recombination in the nc-Si centers.

  9. Structure-property relations in amorphous carbon for photovoltaics

    SciTech Connect (OSTI)

    Risplendi, Francesca; Cicero, Giancarlo; Bernardi, Marco; Grossman, Jeffrey C.

    2014-07-28

    Carbon is emerging as a material with great potential for photovoltaics (PV). However, the amorphous form (a-C) has not been studied in detail as a PV material, even though it holds similarities with amorphous Silicon (a-Si) that is widely employed in efficient solar cells. In this work, we correlate the structure, bonding, stoichiometry, and hydrogen content of a-C with properties linked to PV performance such as the electronic structure and optical absorption. We employ first-principles molecular dynamics and density functional theory calculations to generate and analyze a set of a-C structures with a range of densities and hydrogen concentrations. We demonstrate that optical and electronic properties of interest in PV can be widely tuned by varying the density and hydrogen content. For example, sunlight absorption in a-C films can significantly exceed that of a same thickness of a-Si for a range of densities and H contents in a-C. Our results highlight promising features of a-C as the active layer material of thin-film solar cells.

  10. Amorphous-diamond electron emitter

    DOE Patents [OSTI]

    Falabella, Steven

    2001-01-01

    An electron emitter comprising a textured silicon wafer overcoated with a thin (200 .ANG.) layer of nitrogen-doped, amorphous-diamond (a:D-N), which lowers the field below 20 volts/micrometer have been demonstrated using this emitter compared to uncoated or diamond coated emitters wherein the emission is at fields of nearly 60 volts/micrometer. The silicon/nitrogen-doped, amorphous-diamond (Si/a:D-N) emitter may be produced by overcoating a textured silicon wafer with amorphous-diamond (a:D) in a nitrogen atmosphere using a filtered cathodic-arc system. The enhanced performance of the Si/a:D-N emitter lowers the voltages required to the point where field-emission displays are practical. Thus, this emitter can be used, for example, in flat-panel emission displays (FEDs), and cold-cathode vacuum electronics.

  11. Large-area, triple-junction a-Si alloy production scale-up. Semiannual subcontract report, 17 March 1994--18 September 1994

    SciTech Connect (OSTI)

    Oswald, R.; Morris, J. [Solarex Corp., Newtown, PA (United States). Thin Film Div.

    1995-03-01

    This report describes work performed under a 3-year subcontract to advance Solarex`s photovoltaic (PV) manufacturing technologies, reduce its hydrogenated amorphous silicon (a-Si:H) module production costs, increase module performance, and expand the Solarex commercial production capacity. During the period covered by this report, Solarex focused on (1) improving deposition of the front contact, (2) investigating alternate feed stocks for the front contact, (3) maximizing throughput and area utilization for all laser scribes, (4) optimizing a-Si:H deposition equipment to achieve uniform deposition over large areas, (5) optimizing the triple-junction module fabrication process, (6) evaluating the materials to deposit the rear contact, and (7) optimizing the combination of isolation scribe and encapsulant to pass the wet high-potential test.

  12. Method of forming buried oxide layers in silicon

    DOE Patents [OSTI]

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2000-01-01

    A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

  13. Electroabsorption and transport measurements and modeling in amorphous-silicon-based solar cells: Phase I technical progress report, 24 March 1998--23 March 1999

    SciTech Connect (OSTI)

    Schiff, E. A.; Lyou, J.; Kopidakis, N.; Rao, P.; Yuan, Q.

    1999-12-17

    This report describes work done by the Syracuse University during Phase 1 of this subcontract. Researchers performed work in the following areas: (1) In ``Electroabsorption measurements and built-in potentials in a-Si:H-based solar cells and devices'', researchers obtained an estimate of Vbi = 1.17 V in cells with a-SiGe:H absorber layers from United Solar Systems Corp. (2) In ``Solar cell modeling employing the AMPS computer program'', researchers began operating a simple AMPS modeling site and explored the effect of conduction bandtail width on Voc computed analytical approximations and the AMPS program. The quantitative differences between the two procedures are discussed. (3) In ``Drift mobility measurements in a-Si:H made with high hydrogen dilution'', researchers measured electron and hole mobilities in several n/i/Ni (semitransparent) cells from Pennsylvania State University with a-Si absorber layers made under maximal hydrogen dilution and found a modest increase in hole mobility in these materials compared to conventional a-Si:H. (4) In ``Electroabsorption spectroscopy in solar cells'', researchers discovered and interpreted an infrared absorption band near 1.0 eV, which they believe is caused by dopants and defects at the n/i interface of cells, and which also has interesting implications for the nature of electroabsorption and for the doping mechanism in n-type material.

  14. Thermal decomposition of silane to form hydrogenated amorphous Si film

    DOE Patents [OSTI]

    Strongin, Myron; Ghosh, Arup K.; Wiesmann, Harold J.; Rock, Edward B.; Lutz, III, Harry A.

    1980-01-01

    This invention relates to hydrogenated amorphous silicon produced by thermally decomposing silano (SiH.sub.4) or other gases comprising H and Si, at elevated temperatures of about 1700.degree.-2300.degree. C., and preferably in a vacuum of about 10.sup.-8 to 10.sup.-4 torr, to form a gaseous mixture of atomic hydrogen and atomic silicon, and depositing said gaseous mixture onto a substrate outside said source of thermal decomposition to form hydrogenated amorphous silicon.

  15. Thermal decomposition of silane to form hydrogenated amorphous Si

    DOE Patents [OSTI]

    Strongin, M.; Ghosh, A.K.; Wiesmann, H.J.; Rock, E.B.; Lutz, H.A. III

    Hydrogenated amorphous silicon is produced by thermally decomposing silane (SiH/sub 4/) or other gases comprising H and Si, at elevated temperatures of about 1700 to 2300/sup 0/C, in a vacuum of about 10/sup -8/ to 10/sup -4/ torr. A gaseous mixture is formed of atomic hydrogen and atomic silicon. The gaseous mixture is deposited onto a substrate to form hydrogenated amorphous silicon.

  16. Structural and photovoltaic properties of a-Si (SNc)/c-Si heterojunction fabricated by EBPVD technique

    SciTech Connect (OSTI)

    Demiro?lu, D.; Kazmanli, K.; Urgen, M.; Tatar, B.

    2013-12-16

    In last two decades sculptured thin films are very attractive for researches. Some properties of these thin films, like high porosity correspondingly high large surface area, controlled morphology; bring into prominence on them. Sculptured thin films have wide application areas as electronics, optics, mechanics, magnetic and chemistry. Slanted nano-columnar (SnC) thin films are a type of sculptured thin films. In this investigation SnC thin films were growth on n-type crystalline Si(100) and p-type crystalline Si(111) via ultra-high vacuum electron beam evaporation technique. The structural and morphological properties of the amorphous silicon thin films were investigated by XRD, Raman and FE-SEM analysis. According to the XRD and Raman analysis the structure of thin film was amorphous and FE-SEM analysis indicated slanted nano-columns were formed smoothly. Slanted nano-columns a-Si/c-Si heterojunction were prepared as using a photovoltaic device. In this regard we were researched photovoltaic properties of these heterojunction with current-voltage characterization under dark and illumination conditions. Electrical parameters were determined from the current-voltage characteristic in the dark conditions zero-bias barrier height ?{sub B0}?=?0.83?1.00eV; diode ideality factor ??=?11.71?10.73; series resistance R{sub s}?=?260?31.1 k? and shunt resistance R{sub sh}?=?25.71?63.5 M? SnC a-Si/n-Si and SnC a-Si/p-Si heterojunctions shows a pretty good photovoltaic behavior about 10{sup 3}- 10{sup 4} times. The obtained photovoltaic parameters are such as short circuit current density J{sub sc} 83-40 mA/m{sup 2}, open circuit voltage V{sub oc} 900-831 mV.

  17. Development of Thin Film Silicon Solar Cell Using Inkjet Printed Silicon and Other Inkjet Processes: Cooperative Research and Development Final Report, CRADA Number CRD-07-260

    SciTech Connect (OSTI)

    Sopori, B.

    2012-04-01

    The cost of silicon photovoltaics (Si-PV) can be greatly lowered by developing thin-film crystalline Si solar cells on glass or an equally lower cost substrate. Typically, Si film is deposited by thermal evaporation, plasma enhanced chemical vapor deposition, and sputtering. NREL and Silexos have worked under a CRADA to develop technology to make very low cost solar cells using liquid organic precursors. Typically, cyclopentasilane (CPS) is deposited on a glass substrate and then converted into an a-Si film by UV polymerization followed by low-temperature optical process that crystallizes the amorphous layer. This technique promises to be a very low cost approach for making a Si film.

  18. Large-area triple-junction a-Si alloy production scaleup. Annual subcontract report, 17 March 1993--18 March 1994

    SciTech Connect (OSTI)

    Oswald, R.; Morris, J.

    1994-11-01

    The objective of this subcontract over its three-year duration is to advance Solarex`s photovoltaic manufacturing technologies, reduce its a-Si:H module production costs, increase module performance and expand the Solarex commercial production capacity. Solarex shall meet these objectives by improving the deposition and quality of the transparent front contact, by optimizing the laser patterning process, scaling-up the semiconductor deposition process, improving the back contact deposition, scaling-up and improving the encapsulation and testing of its a-Si:H modules. In the Phase 2 portion of this subcontract, Solarex focused on improving deposition of the front contact, investigating alternate feed stocks for the front contact, maximizing throughput and area utilization for all laser scribes, optimizing a-Si:H deposition equipment to achieve uniform deposition over large-areas, optimizing the triple-junction module fabrication process, evaluating the materials to deposit the rear contact, and optimizing the combination of isolation scribe and encapsulant to pass the wet high potential test. Progress is reported on the following: Front contact development; Laser scribe process development; Amorphous silicon based semiconductor deposition; Rear contact deposition process; Frit/bus/wire/frame; Materials handling; and Environmental test, yield and performance analysis.

  19. More stable hybrid organic solar cells deposited on amorphous Si electron transfer layer

    SciTech Connect (OSTI)

    Samiee, Mehran; Modtland, Brian; Dalal, Vikram L.; Aidarkhanov, Damir

    2014-05-26

    We report on defect densities, performance, and stability of organic/inorganic hybrid solar cells produced using n-doped inorganic amorphous silicon-carbide layers as the electron transport layer (ETL). The organic material was poly-3-hexyl-thiophene (P3HT) and heterojunction was formed using phenyl-C{sub 71}-Butyric-Acid-Methyl Ester (PCBM). For comparison, inverted solar cells fabricated using Cs{sub 2}CO{sub 3} as ETL were fabricated. Defect densities and subgap quantum efficiency curves were found to be nearly identical for both types of cells. The cells were subjected to 2xsun illumination and it was found that the cells produced using doped a-Si as ETL were much more stable than the cells produced using Cs{sub 2}CO{sub 3}.

  20. Low Cost Solar Cells basd on amorphous silicon electrodeposited from organic solvents. Technical quarterly progress report No. 3, March 1-May 31, 1979

    SciTech Connect (OSTI)

    Kroger, F.A.

    1980-01-01

    Electrolysis experiments were carried out using tetra ethyl ortho silicate plus propylene carbonate or 1-chloropropane or acetic acid or formamide and ammonium hexafluorosilicate plus formamide. These experiments yielded deposits which vary in colour between white and black with greyish white, light or dark brown as intermediate colours depending on the deposition conditions. Energy dispersive x-ray analysis in the scanning electron microscope indicated the deposits to contain large concentrations of silicon; infrared absorption and reflection studied showed bands characteristic of Si-O, Si-Cl or Si-F vibrations and thus indicates the presence of these elements in the films. Determination of carrier type in doped deposits by hot point probe method was not successful.

  1. National solar technology roadmap: Film-silicon PV

    SciTech Connect (OSTI)

    Keyes, Brian

    2007-06-01

    Silicon photovoltaic (PV) technologies are addressed in two different technology roadmaps: Film-Silicon PV and Wafer-Silicon PV. This Film-Silicon PV roadmap applies to all silicon-film technologies that rely on a supporting substrate such as glass, polymer, aluminum, stainless steel, or metallurgical-grade silicon. Such devices typically use amorphous, nanocrystalline, fine-grained polycrystalline, or epitaxial silicon layers that are 1–20 μm thick.

  2. Electrodeposited copper front metallization for silicon heterojunction solar cells: materials and processes

    SciTech Connect (OSTI)

    Geissbühler, J.; Martin de Nicolas, S.; Faes, A.; Lachowicz, A.; Tomasi, A.; Paviet-Salomon, B.; Lachenal, D.; Papet, P.; Badel, N.; Barraud, L.; Descoeudres, A.; Despeisse, M.; De Wolf, S.; Ballif, C.

    2014-10-20

    Even though screen-printing of low-temperature silver paste remains the state-of-the-art technique for the front-metallization of SHJ solar cells, recent studies have demonstrated large efficiency improvements when copper-electroplated contacts are used instead of screen-printed ones. However, due to the new materials and the new processes introduced by this technique, it is crucial to individually investigate their compatibility with the SHJ cell structure. In this study, we present a detailed analysis of how the performances of SHJ devices may be modified by these new materials and processes. First, effects on the amorphous silicon (a-Si:H) passivation have been studied for various processes such as DI water rinsing, dips in a copper removal solution and direct evaporation of copper on the a-Si:H. Finally, copper electroplating technique has been adapted in order to be applied to more complex cell structures such as high-efficiency IBC-SHJ.

  3. .beta.-silicon carbide protective coating and method for fabricating same

    DOE Patents [OSTI]

    Carey, Paul G.; Thompson, Jesse B.

    1994-01-01

    A polycrystalline beta-silicon carbide film or coating and method for forming same on components, such as the top of solar cells, to act as an extremely hard protective surface, and as an anti-reflective coating. This is achieved by DC magnetron co-sputtering of amorphous silicon and carbon to form a SiC thin film onto a surface, such as a solar cell. The thin film is then irradiated by a pulsed energy source, such as an excimer laser, to synthesize the poly- or .mu.c-SiC film on the surface and produce .beta.--SiC. While the method of this invention has primary application in solar cell manufacturing, it has application wherever there is a requirement for an extremely hard surface.

  4. [beta]-silicon carbide protective coating and method for fabricating same

    DOE Patents [OSTI]

    Carey, P.G.; Thompson, J.B.

    1994-11-01

    A polycrystalline beta-silicon carbide film or coating and method for forming same on components, such as the top of solar cells, to act as an extremely hard protective surface, and as an anti-reflective coating are disclosed. This is achieved by DC magnetron co-sputtering of amorphous silicon and carbon to form a SiC thin film onto a surface, such as a solar cell. The thin film is then irradiated by a pulsed energy source, such as an excimer laser, to synthesize the poly- or [mu]c-SiC film on the surface and produce [beta]-SiC. While the method of this invention has primary application in solar cell manufacturing, it has application wherever there is a requirement for an extremely hard surface. 3 figs.

  5. Sputtered a-silicon tunneling barriers for Nb-Nb Josephson junctions

    SciTech Connect (OSTI)

    Smith, L.N.; Jillie, D.W.; Kroger, H.; Thaxter, J.B.

    1982-11-01

    The authors have developed an IC-compatible process for fabricating Josephson tunnel junctions, which uses dc magnetron-sputtered Nb films as both base and counterelectrodes, and rf-sputtered amorphous silicon as the tunneling barrier. Optical reflectivity measurements have been used to study the silicon barrier, and to allow precise determination of the barrier thickness. The Josephson current density varies exponentially -over several orders of magnitude -- with the barrier thickness. The product of the critical current and subgap resistance V /SUB m/ is constant over this wide range of current density. The specific capacitance of these junctions is about 2.5 ..mu..f/cm/sup 2/ at a current density of a few hundred A/cm/sup 2/. This is lower than the value for lead-alloy junctions, about 4.3 ..mu..f/cm/sup 2/, and is consistent with the measured thickness and dielectric constant of the a-Si barrier.

  6. Diamond-silicon carbide composite

    DOE Patents [OSTI]

    Qian, Jiang; Zhao, Yusheng

    2006-06-13

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5–8 GPa, T=1400K–2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.dot.m1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  7. Diamond-silicon carbide composite

    DOE Patents [OSTI]

    Qian, Jiang; Zhao, Yusheng

    2006-06-13

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=58 GPa, T=1400K2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.dot.m1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  8. Amorphous metal composites

    DOE Patents [OSTI]

    Byrne, Martin A. (Troy, NY); Lupinski, John H. (Scotia, NY)

    1984-01-01

    An improved amorphous metal composite and process of making the composite. The amorphous metal composite comprises amorphous metal (e.g. iron) and a low molecular weight thermosetting polymer binder. The process comprises placing an amorphous metal in particulate form and a thermosetting polymer binder powder into a container, mixing these materials, and applying heat and pressure to convert the mixture into an amorphous metal composite.

  9. Tin induced a-Si crystallization in thin films of Si-Sn alloys

    SciTech Connect (OSTI)

    Neimash, V. E-mail: oleks.goushcha@nuportsoft.com; Poroshin, V.; Goushcha, A. O. E-mail: oleks.goushcha@nuportsoft.com; Shepeliavyi, P.; Yukhymchuk, V.; Melnyk, V.; Kuzmich, A.; Makara, V.

    2013-12-07

    Effects of tin doping on crystallization of amorphous silicon were studied using Raman scattering, Auger spectroscopy, scanning electron microscopy, and X-ray fluorescence techniques. Formation of silicon nanocrystals (24?nm in size) in the amorphous matrix of Si{sub 1?x}Sn{sub x}, obtained by physical vapor deposition of the components in vacuum, was observed at temperatures around 300?C. The aggregate volume of nanocrystals in the deposited film of Si{sub 1?x}Sn{sub x} exceeded 60% of the total film volume and correlated well with the tin content. Formation of structures with ?80% partial volume of the nanocrystalline phase was also demonstrated. Tin-induced crystallization of amorphous silicon occurred only around the clusters of metallic tin, which suggested the crystallization mechanism involving an interfacial molten Si:Sn layer.

  10. Amorphization and nanocrystallization of silcon under shock compression

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Remington, B. A.; Wehrenberg, C. E.; Zhao, S.; Hahn, E. N.; Kad, B.; Bringa, E. M.; Meyers, M. A.

    2015-11-06

    High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon unveiled remarkable structural changes above a pressure threshold. Two distinct amorphous regions were identified: (a) a bulk amorphous layer close to the surface and (b) amorphous bands initially aligned with {111} slip planes. Further increase of the laser energy leads to the re-crystallization of amorphous silicon into nanocrystals with high concentration of nano-twins. This amorphization is produced by the combined effect of high magnitude hydrostatic and shear stresses under dynamic shock compression. Shock-induced defects play a very important role in the onset of amorphization. Calculations of the free energymore » changes with pressure and shear, using the Patel-Cohen methodology, are in agreement with the experimental results. Molecular dynamics simulation corroborates the amorphization, showing that it is initiated by the nucleation and propagation of partial dislocations. As a result, the nucleation of amorphization is analyzed qualitatively by classical nucleation theory.« less

  11. High-efficiency silicon heterojunction solar cells: Status and perspectives

    SciTech Connect (OSTI)

    De Wolf, S.

    2015-04-27

    Silicon heterojunction technology (HJT) uses silicon thin-film deposition techniques to fabricate photovoltaic devices from mono-crystalline silicon wafers (c-Si). This enables energy-conversion efficiencies above 21 %, also at industrial-production level. In this presentation we review the present status of this technology and point out recent trends. We first discuss how the properties of thin hydrogenated amorphous silicon (a-Si:H) films can be exploited to fabricate passivating contacts, which is the key to high- efficiency HJT solar cells. Such contacts enable very high operating voltages, approaching the theoretical limits, and yield small temperature coefficients. With this approach, an increasing number of groups are reporting devices with conversion efficiencies well over 20 % on n-type wafers, Panasonic leading the field with 24.7 %. Exciting results have also been obtained on p-type wafers. Despite these high voltages, important efficiency gains can still be made in fill factor and optical design. This requires improved understanding of carrier transport across device interfaces and reduced parasitic absorption in HJT solar cells. For the latter, several strategies can be followed: Short- wavelength losses can be reduced by replacing the front a-Si:H films with wider-bandgap window layers, such as silicon alloys or even metal oxides. Long-wavelength losses are mitigated by introducing new high-mobility TCO’s such as hydrogenated indium oxide, and also by designing new rear reflectors. Optical shadow losses caused by the front metalisation grid are significantly reduced by replacing printed silver electrodes with fine-line plated copper contacts, leading also to possible cost advantages. The ultimate approach to minimize optical losses is the implementation of back-contacted architectures, which are completely devoid of grid shadow losses and parasitic absorption in the front layers can be minimized irrespective of electrical transport requirements. The

  12. High-efficiency silicon heterojunction solar cells: Status and perspectives

    SciTech Connect (OSTI)

    De Wolf, S.; Geissbuehler, J.; Loper, P.; Martin de Nicholas, S.; Seif, J.; Tomasi, A.; Ballif, C.

    2015-05-11

    Silicon heterojunction technology (HJT) uses silicon thin-film deposition techniques to fabricate photovoltaic devices from mono-crystalline silicon wafers (c-Si). This enables energy-conversion efficiencies above 21 %, also at industrial-production level. In this presentation we review the present status of this technology and point out recent trends. We first discuss how the properties of thin hydrogenated amorphous silicon (a-Si:H) films can be exploited to fabricate passivating contacts, which is the key to high- efficiency HJT solar cells. Such contacts enable very high operating voltages, approaching the theoretical limits, and yield small temperature coefficients. With this approach, an increasing number of groups are reporting devices with conversion efficiencies well over 20 % on both-sides contacted n-type cells, Panasonic leading the field with 24.7 %. Exciting results have also been obtained on p-type wafers. Despite these high voltages, important efficiency gains can still be made in fill factor and optical design. This requires improved understanding of carrier transport across device interfaces and reduced parasitic absorption in HJT solar cells. For the latter, several strategies can be followed: Short-wavelength losses can be reduced by replacing the front a-Si:H films with wider-bandgap window layers, such as silicon alloys or even metal oxides. Long- wavelength losses are mitigated by introducing new high-mobility TCO’s such as hydrogenated indium oxide, and also by designing new rear reflectors. Optical shadow losses caused by the front metallization grid are significantly reduced by replacing printed silver electrodes with fine-line plated copper contacts, leading also to possible cost advantages. The ultimate approach to minimize optical losses is the implementation of back-contacted architectures, which are completely devoid of grid shadow losses and parasitic absorption in the front layers can be minimized irrespective of electrical

  13. Amorphous diamond films

    DOE Patents [OSTI]

    Falabella, Steven

    1998-01-01

    Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions.

  14. Method for processing silicon solar cells

    DOE Patents [OSTI]

    Tsuo, Y. Simon; Landry, Marc D.; Pitts, John R.

    1997-01-01

    The instant invention teaches a novel method for fabricating silicon solar cells utilizing concentrated solar radiation. The solar radiation is concentrated by use of a solar furnace which is used to form a front surface junction and back-surface field in one processing step. The present invention also provides a method of making multicrystallline silicon from amorphous silicon. The invention also teaches a method of texturing the surface of a wafer by forming a porous silicon layer on the surface of a silicon substrate and a method of gettering impurities. Also contemplated by the invention are methods of surface passivation, forming novel solar cell structures, and hydrogen passivation.

  15. Method for processing silicon solar cells

    DOE Patents [OSTI]

    Tsuo, Y.S.; Landry, M.D.; Pitts, J.R.

    1997-05-06

    The instant invention teaches a novel method for fabricating silicon solar cells utilizing concentrated solar radiation. The solar radiation is concentrated by use of a solar furnace which is used to form a front surface junction and back-surface field in one processing step. The present invention also provides a method of making multicrystalline silicon from amorphous silicon. The invention also teaches a method of texturing the surface of a wafer by forming a porous silicon layer on the surface of a silicon substrate and a method of gettering impurities. Also contemplated by the invention are methods of surface passivation, forming novel solar cell structures, and hydrogen passivation. 2 figs.

  16. Diamond-silicon carbide composite and method

    DOE Patents [OSTI]

    Zhao, Yusheng

    2011-06-14

    Uniformly dense, diamond-silicon carbide composites having high hardness, high fracture toughness, and high thermal stability are prepared by consolidating a powder mixture of diamond and amorphous silicon. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPam.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness.

  17. Silicon Oxynitride Thin Film Barriers for PV Packaging (Poster)

    SciTech Connect (OSTI)

    del Cueto, J. A.; Glick, S. H.; Terwilliger, K. M.; Jorgensen, G. J.; Pankow, J. W.; Keyes, B. M.; Gedvilas, L. M.; Pern, F. J.

    2006-10-03

    Dielectric, adhesion-promoting, moisture barriers comprised of silicon oxynitride thin film materials (SiOxNy with various material stoichiometric compositions x,y) were applied to: 1) bare and pre-coated soda-lime silicate glass (coated with transparent conductive oxide SnO2:F and/or aluminum), and polymer substrates (polyethylene terephthalate, PET, or polyethylene napthalate, PEN); plus 2) pre- deposited photovoltaic (PV) cells and mini-modules consisting of amorphous silicon (a-Si) and copper indium gallium diselenide (CIGS) thin-film PV technologies. We used plasma enhanced chemical vapor deposition (PECVD) process with dilute silane, nitrogen, and nitrous oxide/oxygen gas mixtures in a low-power (< or = 10 milliW per cm2) RF discharge at ~ 0.2 Torr pressure, and low substrate temperatures < or = 100(degrees)C, over deposition areas ~ 1000 cm2. Barrier properties of the resulting PV cells and coated-glass packaging structures were studied with subsequent stressing in damp-heat exposure at 85(degrees)C/85% RH. Preliminary results on PV cells and coated glass indicate the palpable benefits of the barriers in mitigating moisture intrusion and degradation of the underlying structures using SiOxNy coatings with thicknesses in the range of 100-200 nm.

  18. Method for producing silicon thin-film transistors with enhanced forward current drive

    DOE Patents [OSTI]

    Weiner, Kurt H.

    1998-01-01

    A method for fabricating amorphous silicon thin film transistors (TFTs) with a polycrystalline silicon surface channel region for enhanced forward current drive. The method is particularly adapted for producing top-gate silicon TFTs which have the advantages of both amorphous and polycrystalline silicon TFTs, but without problem of leakage current of polycrystalline silicon TFTs. This is accomplished by selectively crystallizing a selected region of the amorphous silicon, using a pulsed excimer laser, to create a thin polycrystalline silicon layer at the silicon/gate-insulator surface. The thus created polysilicon layer has an increased mobility compared to the amorphous silicon during forward device operation so that increased drive currents are achieved. In reverse operation the polysilicon layer is relatively thin compared to the amorphous silicon, so that the transistor exhibits the low leakage currents inherent to amorphous silicon. A device made by this method can be used, for example, as a pixel switch in an active-matrix liquid crystal display to improve display refresh rates.

  19. Method for producing silicon thin-film transistors with enhanced forward current drive

    DOE Patents [OSTI]

    Weiner, K.H.

    1998-06-30

    A method is disclosed for fabricating amorphous silicon thin film transistors (TFTs) with a polycrystalline silicon surface channel region for enhanced forward current drive. The method is particularly adapted for producing top-gate silicon TFTs which have the advantages of both amorphous and polycrystalline silicon TFTs, but without problem of leakage current of polycrystalline silicon TFTs. This is accomplished by selectively crystallizing a selected region of the amorphous silicon, using a pulsed excimer laser, to create a thin polycrystalline silicon layer at the silicon/gate-insulator surface. The thus created polysilicon layer has an increased mobility compared to the amorphous silicon during forward device operation so that increased drive currents are achieved. In reverse operation the polysilicon layer is relatively thin compared to the amorphous silicon, so that the transistor exhibits the low leakage currents inherent to amorphous silicon. A device made by this method can be used, for example, as a pixel switch in an active-matrix liquid crystal display to improve display refresh rates. 1 fig.

  20. Amorphous diamond films

    DOE Patents [OSTI]

    Falabella, S.

    1998-06-09

    Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

  1. Amorphous metal alloy

    DOE Patents [OSTI]

    Wang, R.; Merz, M.D.

    1980-04-09

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  2. High efficiency solar cells combining a perovskite and a silicon heterojunction solar cells via an optical splitting system

    SciTech Connect (OSTI)

    Uzu, Hisashi E-mail: npark@skku.edu; Ichikawa, Mitsuru; Hino, Masashi; Nakano, Kunihiro; Meguro, Tomomi; Yamamoto, Kenji; Hernández, José Luis; Kim, Hui-Seon; Park, Nam-Gyu E-mail: npark@skku.edu

    2015-01-05

    We have applied an optical splitting system in order to achieve very high conversion efficiency for a full spectrum multi-junction solar cell. This system consists of multiple solar cells with different band gap optically coupled via an “optical splitter.” An optical splitter is a multi-layered beam splitter with very high reflection in the shorter-wave-length range and very high transmission in the longer-wave-length range. By splitting the incident solar spectrum and distributing it to each solar cell, the solar energy can be managed more efficiently. We have fabricated optical splitters and used them with a wide-gap amorphous silicon (a-Si) solar cell or a CH{sub 3}NH{sub 3}PbI{sub 3} perovskite solar cell as top cells, combined with mono-crystalline silicon heterojunction (HJ) solar cells as bottom cells. We have achieved with a 550 nm cutoff splitter an active area conversion efficiency of over 25% using a-Si and HJ solar cells and 28% using perovskite and HJ solar cells.

  3. Epitaxial Crystal Silicon Absorber Layers and Solar Cells Grown at 1.8 Microns per Minute: Preprint

    SciTech Connect (OSTI)

    Bobela, D. C.; Teplin, C. W.; Young, D. L.; Branz, H. M.; Stradins, P.

    2011-07-01

    We have grown device-quality epitaxial silicon thin films at growth rates up to 1.8 ?m/min, using hot-wire chemical vapor deposition from silane at substrate temperatures below 750 degrees C. At these rates, which are more than 30 times faster than those used by the amorphous and nanocrystalline Si industry, capital costs for large-scale solar cell production would be dramatically reduced, even for cell absorber layers up to 10 ?m thick. We achieved high growth rates by optimizing the three key parameters: silane flow, depletion, and filament geometry, based on our model developed earlier. Hydrogen coverage of the filament surface likely limits silane decomposition and growth rate at high system pressures. No considerable deterioration in PV device performance is observed when grown at high rate, provided that the epitaxial growth is initiated at low rate. A simple mesa device structure (wafer/epi Si/a-Si(i)/a-Si:H(p)/ITO) with a 2.3 um epitaxial silicon absorber layer was grown at 700 nm/min. The finished device had an open-circuit voltage of 0.424 V without hydrogenation treatment.

  4. Silicone metalization

    DOE Patents [OSTI]

    Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

    2006-12-05

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  5. Silicone metalization

    DOE Patents [OSTI]

    Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

    2008-12-09

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  6. Dependence of short and intermediate-range order on preparation in experimental and modeled pure a-Si

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Holmstrom, Eero; Haberl, Bianca; Pakarinen, Olli H.; Nordlund, Kai; Djurabekova, Flyura; Arenal, Raul; Williams, James S.; Bradby, Jodie E.; Petersen, Timothy C.; Liu, Amelia

    2016-02-20

    Variability in the short-to-intermediate range order of pure amorphous silicon prepared by different experimental and computational techniques is probed by measuring mass density, atomic coordination, bond-angle deviation, and dihedral angle deviation. It is found that there is significant variability in order parameters at these length scales in this archetypal covalently bonded, monoatomic system. This diversity strongly reflects preparation technique and thermal history in both experimental and simulated systems. Experiment and simulation do not fully quantitatively agree, partly due to differences in the way parameters are accessed. However, qualitative agreement in the trends is identified. Relaxed forms of amorphous silicon closelymore » resemble continuous random networks generated by a hybrid method of bond-switching Monte Carlo and molecular dynamics simulation. As-prepared ion implanted amorphous silicon can be adequately modeled using a structure generated from amorphization via ion bombardement using energetic recoils. Preparation methods which narrowly avoid crystallization such as experimental pressure-induced amorphization or simulated melt-quenching result in inhomogeneous structures that contain regions with significant variations in atomic ordering. Ad hoc simulated structures containing small (1 nm) diamond cubic crystal inclusions were found to possess relatively high bond-angle deviations and low dihedral angle deviations, a trend that could not be reconciled with any experimental material.« less

  7. Formation of amorphous materials

    DOE Patents [OSTI]

    Johnson, William L.; Schwarz, Ricardo B.

    1986-01-01

    Metastable amorphous or fine crystalline materials are formed by solid state reactions by diffusion of a metallic component into a solid compound or by diffusion of a gas into an intermetallic compound. The invention can be practiced on layers of metals deposited on an amorphous substrate or by intermixing powders with nucleating seed granules. All that is required is that the diffusion of the first component into the second component be much faster than the self-diffusion of the first component. The method is practiced at a temperature below the temperature at which the amorphous phase transforms into one or more crystalline phases and near or below the temperature at which the ratio of the rate of diffusion of the first component to the rate of self-diffusion is at least 10.sup.4. This anomalous diffusion criteria is found in many binary, tertiary and higher ordered systems of alloys and appears to be found in all alloy systems that form amorphous materials by rapid quenching. The method of the invention can totally convert much larger dimensional materials to amorphous materials in practical periods of several hours or less.

  8. Atomic-Layer-Deposited Transparent Electrodes for Silicon Heterojunction Solar Cells

    SciTech Connect (OSTI)

    Demaurex, Benedicte; Seif, Johannes P.; Smit, Sjoerd; Macco, Bart; Kessels, W. M.; Geissbuhler, Jonas; De Wolf, Stefaan; Ballif, Christophe

    2014-11-01

    We examine damage-free transparent-electrode deposition to fabricate high-efficiency amorphous silicon/crystalline silicon heterojunction solar cells. Such solar cells usually feature sputtered transparent electrodes, the deposition of which may damage the layers underneath. Using atomic layer deposition, we insert thin protective films between the amorphous silicon layers and sputtered contacts and investigate their effect on device operation. We find that a 20-nm-thick protective layer suffices to preserve, unchanged, the amorphous silicon layers beneath. Insertion of such protective atomic-layer-deposited layers yields slightly higher internal voltages at low carrier injection levels. However, we identify the presence of a silicon oxide layer, formed during processing, between the amorphous silicon and the atomic-layer-deposited transparent electrode that acts as a barrier, impeding hole and electron collection.

  9. Atomic-Layer-Deposited Transparent Electrodes for Silicon Heterojunction Solar Cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Demaurex, Benedicte; Seif, Johannes P.; Smit, Sjoerd; Macco, Bart; Kessels, W. M.; Geissbuhler, Jonas; De Wolf, Stefaan; Ballif, Christophe

    2014-11-01

    We examine damage-free transparent-electrode deposition to fabricate high-efficiency amorphous silicon/crystalline silicon heterojunction solar cells. Such solar cells usually feature sputtered transparent electrodes, the deposition of which may damage the layers underneath. Using atomic layer deposition, we insert thin protective films between the amorphous silicon layers and sputtered contacts and investigate their effect on device operation. We find that a 20-nm-thick protective layer suffices to preserve, unchanged, the amorphous silicon layers beneath. Insertion of such protective atomic-layer-deposited layers yields slightly higher internal voltages at low carrier injection levels. However, we identify the presence of a silicon oxide layer, formed during processing,more » between the amorphous silicon and the atomic-layer-deposited transparent electrode that acts as a barrier, impeding hole and electron collection.« less

  10. Probing the density of states of two-level tunneling systems in silicon oxide films using superconducting lumped element resonators

    SciTech Connect (OSTI)

    Skacel, S. T.; Kaiser, Ch.; Wuensch, S.; Siegel, M.; Rotzinger, H.; Lukashenko, A.; Jerger, M.; Weiss, G.; Ustinov, A. V.

    2015-01-12

    We have investigated dielectric losses in amorphous silicon oxide (a-SiO) thin films under operating conditions of superconducting qubits (mK temperatures and low microwave powers). For this purpose, we have developed a broadband measurement setup employing multiplexed lumped element resonators using a broadband power combiner and a low-noise amplifier. The measured temperature and power dependences of the dielectric losses are in good agreement with those predicted for atomic two-level tunneling systems (TLS). By measuring the losses at different frequencies, we found that the TLS density of states is energy dependent. This had not been seen previously in loss measurements. These results contribute to a better understanding of decoherence effects in superconducting qubits and suggest a possibility to minimize TLS-related decoherence by reducing the qubit operation frequency.

  11. Small-Angle Neutron Scattering Studies of a-Si:H and a-Si:D

    SciTech Connect (OSTI)

    Williamson, D. L.; Marr, D. W. M.; Nelson, B. P.; Iwaniczko, E.; Yang, J.; Yan, B.; Guha, S.

    2000-01-01

    The heterogeneity of hydrogen and deuterium on the nanometer scale has been probed by samll-angle neutron scattering (SANS) from a-Si:H and a-Si:D films. Films were depsoited by two techniques, plasma-enhanced chemical vapor deposition (PECVD) and hot-wire chemical vapor deposition (HWCVD) using conditions that yield high quality films and devices.

  12. Low cost routes to high purity silicon and derivatives thereof

    DOE Patents [OSTI]

    Laine, Richard M; Krug, David James; Marchal, Julien Claudius; Mccolm, Andrew Stewart

    2013-07-02

    The present invention is directed to a method for providing an agricultural waste product having amorphous silica, carbon, and impurities; extracting from the agricultural waste product an amount of the impurities; changing the ratio of carbon to silica; and reducing the silica to a high purity silicon (e.g., to photovoltaic silicon).

  13. Silica substrate or portion formed from oxidation of monocrystalline silicon

    DOE Patents [OSTI]

    Matzke, Carolyn M.; Rieger, Dennis J.; Ellis, Robert V.

    2003-07-15

    A method is disclosed for forming an inclusion-free silica substrate using a monocrystalline silicon substrate as the starting material and oxidizing the silicon substrate to convert it entirely to silica. The oxidation process is performed from both major surfaces of the silicon substrate using a conventional high-pressure oxidation system. The resulting product is an amorphous silica substrate which is expected to have superior etching characteristics for microfabrication than conventional fused silica substrates. The present invention can also be used to convert only a portion of a monocrystalline silicon substrate to silica by masking the silicon substrate and locally thinning a portion the silicon substrate prior to converting the silicon portion entirely to silica. In this case, the silica formed by oxidizing the thinned portion of the silicon substrate can be used, for example, as a window to provide optical access through the silicon substrate.

  14. Modeling of Silicon Heterojunction Solar Cells

    SciTech Connect (OSTI)

    Luppina, P.; Lugli, P.; Goodnick, S.

    2015-06-14

    Here we present modeling results on crystalline Si/amorphous Si (a-Si) heterojunction solar cells using Sentaurus including various models for defect states in the a-Si barriers, as well as explicit models for the ITO emitter contact. We investigate the impact of the band offsets and barrier heights of the a-Si/c-Si interface, particularly in terms of the open circuit voltage. It is also shown that the solar cell performance is sensitively dependent on the quality of the a-Si in terms of defect states and their distribution, particularly on the emitter side. Finally, we have investigate the role of tunneling and thermionic emission across the heterointerface in terms of transport from the Si to the ITO contact layer

  15. Growth process of microcrystalline silicon studied by combined photoluminescence and Raman investigations

    SciTech Connect (OSTI)

    Klossek, A.; Mankovics, D.; Ratzke, M.; Arguirov, T.; Kittler, M.; Kirner, S.; Gabriel, O.; Stannowski, B.; Schlatmann, R.; Friedrich, F.

    2013-12-14

    Plasma enhanced chemical vapor deposition of silicon on glass substrates leads to formation of silicon amorphous films with partial crystallization of nano-grains in the amorphous matrix. We studied the transition of amorphous to microcrystalline silicon during such deposition. Formation of silicon nano-grains was detected by means of photoluminescence and Raman spectroscopy. The crystalline fraction and the mean size of the nano-grains were estimated by the position and the intensity of the peaks in the Raman spectrum. We showed that the fraction of crystalline silicon in the layers and the size of the nano-grains are strongly dependent on the growth conditions. The photoluminescence spectra exhibit distinct features related to recombination in the amorphous and in the crystalline phases. A significant narrowing of the photoluminescence peak related to the amorphous phase with increasing crystalline fraction indicates a structural modification in the amorphous silicon. It suggests an ordering process occurring before the start of the actual crystallization. A peak at about 1.4 eV was associated with isolated nano-crystalline grains within the amorphous matrix. A correlation between the peak energy and grain size was found, indicating effects of carrier quantum confinement. The experimental results confirm the established theoretical models for growth of microcrystalline silicon films.

  16. Optimal design of one-dimensional photonic crystal back reflectors for thin-film silicon solar cells

    SciTech Connect (OSTI)

    Chen, Peizhuan; Hou, Guofu Zhang, Jianjun Zhang, Xiaodan; Zhao, Ying

    2014-08-14

    For thin-film silicon solar cells (TFSC), a one-dimensional photonic crystal (1D PC) is a good back reflector (BR) because it increases the total internal reflection at the back surface. We used the plane-wave expansion method and the finite difference time domain (FDTD) algorithm to simulate and analyze the photonic bandgap (PBG), the reflection and the absorption properties of a 1D PC and to further explore the optimal 1D PC design for use in hydrogenated amorphous silicon (a-Si:H) solar cells. With identified refractive index contrast and period thickness, we found that the PBG and the reflection of a 1D PC are strongly influenced by the contrast in bilayer thickness. Additionally, light coupled to the top three periods of the 1D PC and was absorbed if one of the bilayers was absorptive. By decreasing the thickness contrast of the absorptive layer relative to the non-absorptive layer, an average reflectivity of 96.7% was achieved for a 1D PC alternatively stacked with a-Si:H and SiO{sub 2} in five periods. This reflectivity was superior to a distributed Bragg reflector (DBR) structure with 93.5% and an Ag film with 93.4%. n-i-p a-Si:H solar cells with an optimal 1D PC-based BR offer a higher short-circuit current density than those with a DBR-based BR or an AZO/Ag-based BR. These results provide new design rules for photonic structures in TFSC.

  17. Diamond-Silicon Carbide Composite And Method For Preparation Thereof

    DOE Patents [OSTI]

    Qian, Jiang; Zhao, Yusheng

    2005-09-06

    Fully dense, diamond-silicon carbide composites are prepared from ball-milled microcrystalline diamond/amorphous silicon powder mixture. The ball-milled powder is sintered (P=5-8 GPa, T=1400K-2300K) to form composites having high fracture toughness. A composite made at 5 GPa/1673K had a measured fracture toughness of 12 MPa.multidot.m.sup.1/2. By contrast, liquid infiltration of silicon into diamond powder at 5 GPa/1673K produces a composite with higher hardness but lower fracture toughness. X-ray diffraction patterns and Raman spectra indicate that amorphous silicon is partially transformed into nanocrystalline silicon at 5 GPa/873K, and nanocrystalline silicon carbide forms at higher temperatures.

  18. Amorphous Binary Alloy Structures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Hope Ishii, Sean Brennan and Arthur Bienenstock SSRL/SLAC Figure 1: Partial Pair Distribution Functions extracted from the scattering patterns obtained at four different photon energies near the Ge and Mo K-absorption edges. Attempting to determine and describe the atomic arrangements in an amorphous material is a daunting prospect. A considerable advance has been made in the anomalous X-ray scattering approach to determining these arrangements in materials containing two atomic species. Up

  19. Solar cell structure incorporating a novel single crystal silicon material

    DOE Patents [OSTI]

    Pankove, Jacques I.; Wu, Chung P.

    1983-01-01

    A novel hydrogen rich single crystal silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystal silicon without out-gassing the hydrogen. The new material can be used to fabricate semiconductor devices such as single crystal silicon solar cells with surface window regions having a greater band gap energy than that of single crystal silicon without hydrogen.

  20. Amorphous metal distribution transformers: The energy-efficient alternative

    SciTech Connect (OSTI)

    Garrity, T.F.

    1994-12-31

    Amorphous metal distribution transformers have been commercially available for the past 13 years. During that time, they have realized the promise of exceptionally high core efficiency as compared to silicon steel transformer cores. Utility planners today must consider all options available to meet the requirements of load growth. While additional generation capacity will be added, many demand-side initiatives are being undertaken as complementary programs to generation expansion. The efficiency improvement provided by amorphous metal distribution transformers deserves to be among the demand-side options. The key to understanding the positive impact of amorphous metal transformer efficiency is to consider the aggregate contribution those transformers can make towards demand reduction. It is estimated that distribution transformer core losses comprise at least 1% of the utility`s peak demand. Because core losses are continuous, any significant reduction in their magnitude is of great significance to the planner. This paper describes the system-wide economic contributions amorphous metal distribution transformers can make to a utility and suggests evaluation techniques that can be used. As a conservation tool, the amorphous metal transformer contributes to reduced power plant emissions. Calibration of those emissions reductions is also discussed in the paper.

  1. Holey Silicon as an Efficient Thermoelectric Material

    SciTech Connect (OSTI)

    Tang, Jinyao; Wang, Hung-Ta; Hyun Lee, Dong; Fardy, Melissa; Huo, Ziyang; Russell, Thomas P.; Yang, Peidong

    2010-09-30

    This work investigated the thermoelectric properties of thin silicon membranes that have been decorated with high density of nanoscopic holes. These ?holey silicon? (HS) structures were fabricated by either nanosphere or block-copolymer lithography, both of which are scalable for practical device application. By reducing the pitch of the hexagonal holey pattern down to 55 nm with 35percent porosity, the thermal conductivity of HS is consistently reduced by 2 orders of magnitude and approaches the amorphous limit. With a ZT value of 0.4 at room temperature, the thermoelectric performance of HS is comparable with the best value recorded in silicon nanowire system.

  2. Fabrication of amorphous diamond films

    DOE Patents [OSTI]

    Falabella, Steven

    1995-01-01

    Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions.

  3. High-Rate Fabrication of a-Si-Based Thin-Film Solar Cells Using Large-Area VHF PECVD Processes

    SciTech Connect (OSTI)

    Deng, Xunming; Fan, Qi Hua

    2011-12-31

    The University of Toledo (UT), working in concert with it’s a-Si-based PV industry partner Xunlight Corporation (Xunlight), has conducted a comprehensive study to develop a large-area (3ft x 3ft) VHF PECVD system for high rate uniform fabrication of silicon absorber layers, and the large-area VHF PECVD processes to achieve high performance a-Si/a-SiGe or a-Si/nc-Si tandem junction solar cells during the period of July 1, 2008 to Dec. 31, 2011, under DOE Award No. DE-FG36-08GO18073. The project had two primary goals: (i) to develop and improve a large area (3 ft × 3 ft) VHF PECVD system for high rate fabrication of > = 8 Å/s a-Si and >= 20 Å/s nc-Si or 4 Å/s a-SiGe absorber layers with high uniformity in film thicknesses and in material structures. (ii) to develop and optimize the large-area VHF PECVD processes to achieve high-performance a-Si/nc-Si or a-Si/a-SiGe tandem-junction solar cells with >= 10% stable efficiency. Our work has met the goals and is summarized in “Accomplishments versus goals and objectives”.

  4. The crystallization of the nanometersized amorphous ceramic powders by ball milling

    SciTech Connect (OSTI)

    Fan, G.J.; Song, X.P.; Li, Y.L.

    1995-12-31

    The nanometersized amorphous Si{sub 3}N{sub 4} and Si-N-C powders are subjected by high-energy ball milling in order to induce a crystallization process. It was found that after initial 4 seconds of milling a-Si{sub 3}N{sub 4} may rapidly crystallize into a mixture of {alpha}-Si{sub 3}N{sub 4} and {beta}-Si{sub 3}N{sub 4} whereas amorphous Si-N-C powders remain in the amorphous state. These results cannot be interpreted with the local effective temperature rise at the collision sites and the increase of the impurity levels which drive the crystallization. The observed structural changes occurring in a-Si{sub 3}N{sub 4} can be attributed to the mechanical deformation which alters the bonding nature of a-Si{sub 3}N{sub 4}. It was concluded that ball milling is an effective tool to induce the crystallization of some amorphous metallic systems.

  5. Performance of Hydrogenated a-Si:H Solar Cells with Downshifting Coating: Preprint

    SciTech Connect (OSTI)

    Nemeth, B.; Xu, Y.; Wang, H.; Sun, T.; Lee, B. G.; Duda, A.; Wang, Q.

    2011-05-01

    We apply a thin luminescent downshifting (LDS) coating to a hydrogenated amorphous Si (a-Si:H) solar cell and study the mechanism of possible current enhancement. The conversion material used in this study converts wavelengths below 400 nm to a narrow line around 615 nm. This material is coated on the front of the glass of the a-Si:H solar cell with a glass/TCO/p/i/n/Ag superstrate configuration. The initial efficiency of the solar cell without the LDS coating is above 9.0 % with open circuit voltage of 0.84 V. Typically, the spectral response below 400 nm of an a-Si:H solar cell is weaker than that at 615 nm. By converting ultraviolet (UV) light to red light, the solar cell will receive more red photons; therefore, solar cell performance is expected to improve. We observe evidence of downshifting in reflectance spectra. The cell Jsc decreases by 0.13 mA/cm2, and loss mechanisms are identified.

  6. 22.5% efficient silicon heterojunction solar cell with molybdenum oxide hole collector

    SciTech Connect (OSTI)

    Geissbühler, Jonas Werner, Jérémie; Martin de Nicolas, Silvia; Hessler-Wyser, Aïcha; Tomasi, Andrea; Niesen, Bjoern; De Wolf, Stefaan; Barraud, Loris; Despeisse, Matthieu; Nicolay, Sylvain; Ballif, Christophe

    2015-08-24

    Substituting the doped amorphous silicon films at the front of silicon heterojunction solar cells with wide-bandgap transition metal oxides can mitigate parasitic light absorption losses. This was recently proven by replacing p-type amorphous silicon with molybdenum oxide films. In this article, we evidence that annealing above 130 °C—often needed for the curing of printed metal contacts—detrimentally impacts hole collection of such devices. We circumvent this issue by using electrodeposited copper front metallization and demonstrate a silicon heterojunction solar cell with molybdenum oxide hole collector, featuring a fill factor value higher than 80% and certified energy conversion efficiency of 22.5%.

  7. Synthesizing Amorphous Pharmaceuticals Using Containerless Processing...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    a yellow amorphous product; in the laser hearth, it forms a white crystalline product. ... pressure created by intense sound waves-to form molecular gels and amorphous solids. ...

  8. Metallic coatings on silicon substrates, and methods of forming metallic coatings on silicon substrates

    DOE Patents [OSTI]

    Branagan, Daniel J.; Hyde, Timothy A.; Fincke, James R.

    2008-03-11

    The invention includes methods of forming a metallic coating on a substrate which contains silicon. A metallic glass layer is formed over a silicon surface of the substrate. The invention includes methods of protecting a silicon substrate. The substrate is provided within a deposition chamber along with a deposition target. Material from the deposition target is deposited over at least a portion of the silicon substrate to form a protective layer or structure which contains metallic glass. The metallic glass comprises iron and one or more of B, Si, P and C. The invention includes structures which have a substrate containing silicon and a metallic layer over the substrate. The metallic layer contains less than or equal to about 2 weight % carbon and has a hardness of at least 9.2 GPa. The metallic layer can have an amorphous microstructure or can be devitrified to have a nanocrystalline microstructure.

  9. Fabrication of amorphous diamond films

    DOE Patents [OSTI]

    Falabella, S.

    1995-12-12

    Amorphous diamond films having a significant reduction in intrinsic stress are prepared by biasing a substrate to be coated and depositing carbon ions thereon under controlled temperature conditions. 1 fig.

  10. Amorphous metal alloy and composite

    DOE Patents [OSTI]

    Wang, Rong; Merz, Martin D.

    1985-01-01

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  11. Structure of Pentacene Monolayers on Amorphous Silicon Oxide...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    typical deposition parameters we use to produce high-performance TFTs. Grazing incidence X-ray diffraction (GIXD) with synchrotron light offers the unique opportunity to study the...

  12. Deposition of device quality low H content, amorphous silicon...

    Office of Scientific and Technical Information (OSTI)

    Solar Energy Research Institute Sponsoring Org: United States Department of Energy Country of Publication: United States Language: English Subject: 36 MATERIALS SCIENCE; 14 SOLAR ...

  13. Atomic Layer Deposition for Stabilization of Amorphous Silicon Anodes

    Office of Energy Efficiency and Renewable Energy (EERE)

    2012 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting

  14. Shock compression of [001] single crystal silicon

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhao, S.; Remington, B.; Hahn, E. N.; Kad, B.; Bringa, E. M.; Meyers, M. A.

    2016-03-14

    Silicon is ubiquitous in our advanced technological society, yet our current understanding of change to its mechanical response at extreme pressures and strain-rates is far from complete. This is due to its brittleness, making recovery experiments difficult. High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon (using impedance-matched momentum traps) unveiled remarkable structural changes observed by transmission electron microscopy. As laser energy increases, corresponding to an increase in peak shock pressure, the following plastic responses are are observed: surface cleavage along {111} planes, dislocations and stacking faults; bands of amorphized material initially forming on crystallographic orientations consistent withmore » dislocation slip; and coarse regions of amorphized material. Molecular dynamics simulations approach equivalent length and time scales to laser experiments and reveal the evolution of shock-induced partial dislocations and their crucial role in the preliminary stages of amorphization. Furthermore, application of coupled hydrostatic and shear stresses produce amorphization below the hydrostatically determined critical melting pressure under dynamic shock compression.« less

  15. Nanostructures having crystalline and amorphous phases

    DOE Patents [OSTI]

    Mao, Samuel S; Chen, Xiaobo

    2015-04-28

    The present invention includes a nanostructure, a method of making thereof, and a method of photocatalysis. In one embodiment, the nanostructure includes a crystalline phase and an amorphous phase in contact with the crystalline phase. Each of the crystalline and amorphous phases has at least one dimension on a nanometer scale. In another embodiment, the nanostructure includes a nanoparticle comprising a crystalline phase and an amorphous phase. The amorphous phase is in a selected amount. In another embodiment, the nanostructure includes crystalline titanium dioxide and amorphous titanium dioxide in contact with the crystalline titanium dioxide. Each of the crystalline and amorphous titanium dioxide has at least one dimension on a nanometer scale.

  16. Compositions of corrosion-resistant Fe-based amorphous metals suitable for producing thermal spray coatings

    DOE Patents [OSTI]

    Farmer, Joseph C; Wong, Frank M.G.; Haslam, Jeffery J; Ji, Xiaoyan; Day, Sumner D; Blue, Craig A; Rivard, John D.K.; Aprigliano, Louis F; Kohler, Leslie K; Bayles, Robert; Lemieux, Edward J; Yang, Nancy; Perepezko, John H; Kaufman, Larry; Heuer, Arthur; Lavernia, Enrique J

    2013-09-03

    A method of coating a surface comprising providing a source of amorphous metal that contains manganese (1 to 3 atomic %), yttrium (0.1 to 10 atomic %), and silicon (0.3 to 3.1 atomic %) in the range of composition given in parentheses; and that contains the following elements in the specified range of composition given in parentheses: chromium (15 to 20 atomic %), molybdenum (2 to 15 atomic %), tungsten (1 to 3 atomic %), boron (5 to 16 atomic %), carbon (3 to 16 atomic %), and the balance iron; and applying said amorphous metal to the surface by a spray.

  17. Compositions of corrosion-resistant Fe-based amorphous metals suitable for producing thermal spray coatings

    DOE Patents [OSTI]

    Farmer, Joseph C.; Wong, Frank M. G.; Haslam, Jeffery J.; Ji, Xiaoyan; Day, Sumner D.; Blue, Craig A.; Rivard, John D. K.; Aprigliano, Louis F.; Kohler, Leslie K.; Bayles, Robert; Lemieux, Edward J.; Yang, Nancy; Perepezko, John H.; Kaufman, Larry; Heuer, Arthur; Lavernia, Enrique J.

    2013-07-09

    A method of coating a surface comprising providing a source of amorphous metal that contains manganese (1 to 3 atomic %), yttrium (0.1 to 10 atomic %), and silicon (0.3 to 3.1 atomic %) in the range of composition given in parentheses; and that contains the following elements in the specified range of composition given in parentheses: chromium (15 to 20 atomic %), molybdenum (2 to 15 atomic %), tungsten (1 to 3 atomic %), boron (5 to 16 atomic %), carbon (3 to 16 atomic %), and the balance iron; and applying said amorphous metal to the surface by a spray.

  18. Method of making selective crystalline silicon regions containing entrapped hydrogen by laser treatment

    DOE Patents [OSTI]

    Pankove, Jacques I.; Wu, Chung P.

    1982-01-01

    A novel hydrogen rich single crystalline silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystalline silicon without out-gasing the hydrogen. The new material can be used to fabricate semi-conductor devices such as single crystalline silicon solar cells with surface window regions having a greater band gap energy than that of single crystalline silicon without hydrogen.

  19. Silicon nitride/silicon carbide composite powders

    DOE Patents [OSTI]

    Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

    1996-06-11

    Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

  20. Annealing studies of amorphous alloys

    SciTech Connect (OSTI)

    Wiley, J.D.; Perepezko, J.H.; Nordman, J.E.

    1983-04-01

    Amorphous films of the alloys Ni-Nb, Ni-Mo, Mo-Si, and W-Si were sputter deposited on single-crystal semiconductor substrates. One-hour crystallization temperatures of the films were determined to within +-25/sup 0/C by annealing and x-ray diffraction measurements. Interdiffusion between Au or Cu overlayers and the amorphous films were studied by annealing combined with Auger Electron Spectroscopy (AES) profiling, and by Rutherford Backscatter (RBS) analysis. Supplementary measurements used to study structural relaxation and crystallization included resistivity as a function of temperature; DTA and DSC; and electron microscopy.

  1. Understanding the Structure of Amorphous Thin Film Hafnia - Final Paper

    SciTech Connect (OSTI)

    Miranda, Andre

    2015-08-27

    Hafnium Oxide (HfO2) amorphous thin films are being used as gate oxides in transistors because of their high dielectric constant (κ) over Silicon Dioxide. The present study looks to find the atomic structure of HfO2 thin films which hasn’t been done with the technique of this study. In this study, two HfO2 samples were studied. One sample was made with thermal atomic layer deposition (ALD) on top of a Chromium and Gold layer on a silicon wafer. The second sample was made with plasma ALD on top of a Chromium and Gold layer on a Silicon wafer. Both films were deposited at a thickness of 50nm. To obtain atomic structure information, Grazing Incidence X-ray diffraction (GIXRD) was carried out on the HfO2 samples. Because of this, absorption, footprint, polarization, and dead time corrections were applied to the scattering intensity data collected. The scattering curves displayed a difference in structure between the ALD processes. The plasma ALD sample showed the broad peak characteristic of an amorphous structure whereas the thermal ALD sample showed an amorphous structure with characteristics of crystalline materials. This appears to suggest that the thermal process results in a mostly amorphous material with crystallites within. Further, the scattering intensity data was used to calculate a pair distribution function (PDF) to show more atomic structure. The PDF showed atom distances in the plasma ALD sample had structure up to 10 Å, while the thermal ALD sample showed the same structure below 10 Å. This structure that shows up below 10 Å matches the bond distances of HfO2 published in literature. The PDF for the thermal ALD sample also showed peaks up to 20 Å, suggesting repeating atomic spacing outside the HfO2 molecule in the sample. This appears to suggest that there is some crystalline structure within the thermal ALD sample.

  2. Imprinting bulk amorphous alloy at room temperature

    SciTech Connect (OSTI)

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.

  3. Amorphization resistance of nano-engineered SiC under heavy ion irradiation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Imada, Kenta; Ishimaru, Manabu; Xue, Haizhou; Zhang, Yanwen; Shannon, Steven C.; Weber, William J.

    2016-06-19

    Silicon carbide (SiC) with a high-density of planar defects (hereafter, ‘nano-engineered SiC’) and epitaxially-grown single-crystalline 3C-SiC were simultaneously irradiated with Au ions at room temperature, in order to compare their relative resistance to radiation-induced amorphization. Furthermore, it was found that the local threshold dose for amorphization is comparable for both samples under 2 MeV Au ion irradiation; whereas, nano-engineered SiC exhibits slightly greater radiation tolerance than single crystalline SiC under 10 MeV Au irradiation. Under 10 MeV Au ion irradiation, the dose for amorphization increased by about a factor of two in both nano-engineered and single crystal SiC due tomore » the local increase in electronic energy loss that enhanced dynamic recovery.« less

  4. Density driven structural transformations in amorphous semiconductor...

    Office of Scientific and Technical Information (OSTI)

    As such, the compresion-decompression process in this systems gives rise to three distict amorphous forms. Authors: Tulk, Christopher A 1 ; dos Santos, Antonio M. 2 ; ...

  5. High damage tolerance of electrochemically lithiated silicon

    SciTech Connect (OSTI)

    Wang, Xueju; Fan, Feifei; Wang, Jiangwei; Wang, Haoran; Tao, Siyu; Yang, Avery; Liu, Yang; Beng Chew, Huck; Mao, Scott X.; Zhu, Ting; Xia, Shuman

    2015-09-24

    Mechanical degradation and resultant capacity fade in high-capacity electrode materials critically hinder their use in high-performance rechargeable batteries. Despite tremendous efforts devoted to the study of the electro–chemo–mechanical behaviours of high-capacity electrode materials, their fracture properties and mechanisms remain largely unknown. In this paper, we report a nanomechanical study on the damage tolerance of electrochemically lithiated silicon. Our in situ transmission electron microscopy experiments reveal a striking contrast of brittle fracture in pristine silicon versus ductile tensile deformation in fully lithiated silicon. Quantitative fracture toughness measurements by nanoindentation show a rapid brittle-to-ductile transition of fracture as the lithium-to-silicon molar ratio is increased to above 1.5. Molecular dynamics simulations elucidate the mechanistic underpinnings of the brittle-to-ductile transition governed by atomic bonding and lithiation-induced toughening. Finally, our results reveal the high damage tolerance in amorphous lithium-rich silicon alloys and have important implications for the development of durable rechargeable batteries.

  6. High damage tolerance of electrochemically lithiated silicon

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Xueju; Fan, Feifei; Wang, Jiangwei; Wang, Haoran; Tao, Siyu; Yang, Avery; Liu, Yang; Beng Chew, Huck; Mao, Scott X.; Zhu, Ting; et al

    2015-09-24

    Mechanical degradation and resultant capacity fade in high-capacity electrode materials critically hinder their use in high-performance rechargeable batteries. Despite tremendous efforts devoted to the study of the electro–chemo–mechanical behaviours of high-capacity electrode materials, their fracture properties and mechanisms remain largely unknown. In this paper, we report a nanomechanical study on the damage tolerance of electrochemically lithiated silicon. Our in situ transmission electron microscopy experiments reveal a striking contrast of brittle fracture in pristine silicon versus ductile tensile deformation in fully lithiated silicon. Quantitative fracture toughness measurements by nanoindentation show a rapid brittle-to-ductile transition of fracture as the lithium-to-silicon molar ratiomore » is increased to above 1.5. Molecular dynamics simulations elucidate the mechanistic underpinnings of the brittle-to-ductile transition governed by atomic bonding and lithiation-induced toughening. Finally, our results reveal the high damage tolerance in amorphous lithium-rich silicon alloys and have important implications for the development of durable rechargeable batteries.« less

  7. Preparation of amorphous sulfide sieves

    DOE Patents [OSTI]

    Siadati, Mohammad H.; Alonso, Gabriel; Chianelli, Russell R.

    2006-11-07

    The present invention involves methods and compositions for synthesizing catalysts/porous materials. In some embodiments, the resulting materials are amorphous sulfide sieves that can be mass-produced for a variety of uses. In some embodiments, methods of the invention concern any suitable precursor (such as thiomolybdate salt) that is exposed to a high pressure pre-compaction, if need be. For instance, in some cases the final bulk shape (but highly porous) may be same as the original bulk shape. The compacted/uncompacted precursor is then subjected to an open-flow hot isostatic pressing, which causes the precursor to decompose and convert to a highly porous material/catalyst.

  8. Stable a-Si:H Based Multijunction Solar Cells with Guidance from Real Time Optics: Annual Report, Phase I: 17 July 1998-16 October 1999

    SciTech Connect (OSTI)

    Wronski, C.R.; Collins, R.W.; Jiao, L.; Ferlauto, A.; Rovira, P.I.; Koval, R.J.; Lu, Z.; Niu, X.

    2000-08-29

    This summary describes tasks of novel improved intrinsic materials for multijunction solar cells, insights into improved stability in materials and solar cells, optimization of solar cell performance with improved intrinsic layers, and optimization of multijunction solar cells. The report characterizes a protocrystalline a-Si:H film growth regime where thin samples retain their amorphous state when their growth time or thickness is limited to small values, even when films are deposited with high hydrogen dilution that results in microcrystalline thick films. The Staebler-Wronski degradation kinetics of films and devices are systematically studied as a function of hydrogen dilution.

  9. Stability and migration of small copper clusters in amorphous dielectrics

    SciTech Connect (OSTI)

    Guzman, David M.; Onofrio, Nicolas; Strachan, Alejandro

    2015-05-21

    We use density functional theory (DFT) to study the thermodynamic stability and migration of copper ions and small clusters embedded in amorphous silicon dioxide. We perform the calculations over an ensemble of statistically independent structures to quantify the role of the intrinsic atomic-level variability in the amorphous matrix affect the properties. The predicted formation energy of a Cu ion in the silica matrix is 2.7 ± 2.4 eV, significantly lower the value for crystalline SiO{sub 2}. Interestingly, we find that Cu clusters of any size are energetically favorable as compared to isolated ions; showing that the formation of metallic clusters does not require overcoming a nucleation barrier as is often assumed. We also find a broad distribution of activation energies for Cu migration, from 0.4 to 1.1 eV. This study provides insights into the stability of nanoscale metallic clusters in silica of interest in electrochemical metallization cell memories and optoelectronics.

  10. Amorphous InGaZnO thin-film transistor active pixel sensor x-ray imager for digital breast tomosynthesis

    SciTech Connect (OSTI)

    Zhao, Chumin; Kanicki, Jerzy

    2014-09-15

    Purpose: The breast cancer detection rate for digital breast tomosynthesis (DBT) is limited by the x-ray image quality. The limiting Nyquist frequency for current DBT systems is around 5?lp/mm, while the fine image details contained in the high spatial frequency region (>5?lp/mm) are lost. Also today the tomosynthesis patient dose is high (0.673.52?mGy). To address current issues, in this paper, for the first time, a high-resolution low-dose organic photodetector/amorphous InGaZnO thin-film transistor (a-IGZO TFT) active pixel sensor (APS) x-ray imager is proposed for next generation DBT systems. Methods: The indirect x-ray detector is based on a combination of a novel low-cost organic photodiode (OPD) and a cesium iodide-based (CsI:Tl) scintillator. The proposed APS x-ray imager overcomes the difficulty of weak signal detection, when small pixel size and low exposure conditions are used, by an on-pixel signal amplification with a significant charge gain. The electrical performance of a-IGZO TFT APS pixel circuit is investigated by SPICE simulation using modified Rensselaer Polytechnic Institute amorphous silicon (a-Si:H) TFT model. Finally, the noise, detective quantum efficiency (DQE), and resolvability of the complete system are modeled using the cascaded system formalism. Results: The result demonstrates that a large charge gain of 31122 is achieved for the proposed high-mobility (520 cm{sup 2}/V?s) amorphous metal-oxide TFT APS. The charge gain is sufficient to eliminate the TFT thermal noise, flicker noise as well as the external readout circuit noise. Moreover, the low TFT (<10{sup ?13} A) and OPD (<10{sup ?8} A/cm{sup 2}) leakage currents can further reduce the APS noise. Cascaded system analysis shows that the proposed APS imager with a 75??m pixel pitch can effectively resolve the Nyquist frequency of 6.67 lp/mm, which can be further improved to ?10?lp/mm if the pixel pitch is reduced to 50??m. Moreover, the detector entrance exposure per projection

  11. Pulsed energy synthesis and doping of silicon carbide

    DOE Patents [OSTI]

    Truher, Joel B.; Kaschmitter, James L.; Thompson, Jesse B.; Sigmon, Thomas W.

    1995-01-01

    A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27.degree.-730.degree. C. is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including hetero-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

  12. Pulsed energy synthesis and doping of silicon carbide

    DOE Patents [OSTI]

    Truher, J.B.; Kaschmitter, J.L.; Thompson, J.B.; Sigmon, T.W.

    1995-06-20

    A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate is disclosed, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27--730 C is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including HETEROJUNCTION-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

  13. Homogeneous fluorescence linewidths for amorphous hosts

    SciTech Connect (OSTI)

    Lyo, S.K.; Orbach, R.

    1980-11-01

    A contribution to the homogeneous linewidth of optical transitions in amorphous hosts is calculated. The microscopic process is diagonal in the phonon interaction with two level systems (TLS) common to amorphous materials, and diagonal in the coupling between TLS and the optical center. The model predicts an optical homogeneous linewidth proportional to the square of the temperature at low temperature.

  14. Imprinting bulk amorphous alloy at room temperature

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the abilitymore » of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.« less

  15. Low temperature front surface passivation of interdigitated back contact silicon heterojunction solar cell

    SciTech Connect (OSTI)

    Shu, Brent; Das, Ujjwal; Jani, Omkar; Hegedus, Steve; Birkmire, Robert

    2009-06-08

    The interdigitated back contact silicon heterojunction (IBC-SHJ) solar cell requires a low temperature front surface passivation/anti-reflection structure. Conventional silicon surface passivation using SiO2 or a-SiNx is performed at temperature higher than 400C, which is not suitable for the IBC-SHJ cell. In this paper, we propose a PECVD a-Si:H/a-SiNx:H/a-SiC:H stack structure to passivate the front surface of crystalline silicon at low temperature. The optical properties and passivation quality of this structure are characterized and solar cells using this structure are fabricated. With 2 nm a-Si:H layer, the stack structure exhibits stable passivation with effective minority carrier lifetime higher than 2 ms, and compatible with IBC-SHJ solar cell processing. A critical advantage of this structure is that the SiC allows it to be HF resistant, thus it can be deposited as the first step in the process. This protects the a-Si/c-Si interface and maintains a low surface recombination velocity.

  16. Solid-state diffusion in amorphous zirconolite

    SciTech Connect (OSTI)

    Yang, C.; Dove, M. T.; Trachenko, K.; Zarkadoula, E.; Todorov, I. T.; Geisler, T.; Brazhkin, V. V.

    2014-11-14

    We discuss how structural disorder and amorphization affect solid-state diffusion, and consider zirconolite as a currently important case study. By performing extensive molecular dynamics simulations, we disentangle the effects of amorphization and density, and show that a profound increase of solid-state diffusion takes place as a result of amorphization. Importantly, this can take place at the same density as in the crystal, representing an interesting general insight regarding solid-state diffusion. We find that decreasing the density in the amorphous system increases pre-factors of diffusion constants, but does not change the activation energy in the density range considered. We also find that atomic species in zirconolite are affected differently by amorphization and density change. Our microscopic insights are relevant for understanding how solid-state diffusion changes due to disorder and for building predictive models of operation of materials to be used to encapsulate nuclear waste.

  17. Ultra Low Density Amorphous Shape Memory polymer Foams. (Conference...

    Office of Scientific and Technical Information (OSTI)

    Ultra Low Density Amorphous Shape Memory polymer Foams. Citation Details In-Document Search Title: Ultra Low Density Amorphous Shape Memory polymer Foams. You are accessing a ...

  18. Transparent electrodes in silicon heterojunction solar cells: Influence on contact passivation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tomasi, Andrea; Sahli, Florent; Seif, Johannes Peter; Fanni, Lorenzo; de Nicolas Agut, Silvia Martin; Geissbuhler, Jonas; Paviet-Salomon, Bertrand; Nicolay, Sylvain; Barraud, Loris; Niesen, Bjoern; et al

    2015-10-26

    Charge carrier collection in silicon heterojunction solar cells occurs via intrinsic/doped hydrogenated amorphous silicon layer stacks deposited on the crystalline silicon wafer surfaces. Usually, both the electron and hole collecting stacks are externally capped by an n-type transparent conductive oxide, which is primarily needed for carrier extraction. Earlier, it has been demonstrated that the mere presence of such oxides can affect the carrier recombination in the crystalline silicon absorber. Here, we present a detailed investigation of the impact of this phenomenon on both the electron and hole collecting sides, including its consequences for the operating voltages of silicon heterojunction solarmore » cells. As a result, we define guiding principles for improved passivating contact design for high-efficiency silicon solar cells.« less

  19. Transparent electrodes in silicon heterojunction solar cells: Influence on contact passivation

    SciTech Connect (OSTI)

    Tomasi, Andrea; Sahli, Florent; Seif, Johannes Peter; Fanni, Lorenzo; de Nicolas Agut, Silvia Martin; Geissbuhler, Jonas; Paviet-Salomon, Bertrand; Nicolay, Sylvain; Barraud, Loris; Niesen, Bjoern; De Wolf, Stefaan; Ballif, Christophe

    2015-10-26

    Charge carrier collection in silicon heterojunction solar cells occurs via intrinsic/doped hydrogenated amorphous silicon layer stacks deposited on the crystalline silicon wafer surfaces. Usually, both the electron and hole collecting stacks are externally capped by an n-type transparent conductive oxide, which is primarily needed for carrier extraction. Earlier, it has been demonstrated that the mere presence of such oxides can affect the carrier recombination in the crystalline silicon absorber. Here, we present a detailed investigation of the impact of this phenomenon on both the electron and hole collecting sides, including its consequences for the operating voltages of silicon heterojunction solar cells. As a result, we define guiding principles for improved passivating contact design for high-efficiency silicon solar cells.

  20. Strong visible electroluminescence from silicon nanocrystals embedded in a silicon carbide film

    SciTech Connect (OSTI)

    Huh, Chul Kim, Tae-Youb; Ahn, Chang-Geun; Kim, Bong Kyu

    2015-05-25

    We report the strong visible light emission from silicon (Si) nanocrystals (NCs) embedded in a Si carbide (SiC) film. Compared to Si NC light-emitting diode (LED) by employing the Si nitride (SiN{sub x}) film as a surrounding matrix, the turn-on voltage of the Si NC LED with the SiC film was significantly decreased by 4 V. This was attributed to a smaller barrier height for injecting the electrons into the Si NCs due to a smaller band gap of SiC film than a SiN{sub x} film. The electroluminescence spectra increases with increasing forward voltage, indicating that the electrons are efficiently injected into the Si NCs in the SiC film. The light output power shows a linear increase with increasing forward voltage. The light emission originated from the Si NCs in a SiC film was quite uniform. The power efficiency of the Si NC LED with the SiC film was 1.56 times larger than that of the Si NC LED with the SiN{sub x} film. The Si NCs in a SiC film show unique advantages and are a promising candidate for application in optical devices.

  1. Purified silicon production system

    DOE Patents [OSTI]

    Wang, Tihu; Ciszek, Theodore F.

    2004-03-30

    Method and apparatus for producing purified bulk silicon from highly impure metallurgical-grade silicon source material at atmospheric pressure. Method involves: (1) initially reacting iodine and metallurgical-grade silicon to create silicon tetraiodide and impurity iodide byproducts in a cold-wall reactor chamber; (2) isolating silicon tetraiodide from the impurity iodide byproducts and purifying it by distillation in a distillation chamber; and (3) transferring the purified silicon tetraiodide back to the cold-wall reactor chamber, reacting it with additional iodine and metallurgical-grade silicon to produce silicon diiodide and depositing the silicon diiodide onto a substrate within the cold-wall reactor chamber. The two chambers are at atmospheric pressure and the system is open to allow the introduction of additional source material and to remove and replace finished substrates.

  2. Corrosion resistant amorphous metals and methods of forming corrosion resistant amorphous metals

    DOE Patents [OSTI]

    Farmer, Joseph C.; Wong, Frank M. G.; Haslam, Jeffery J.; Yang, Nancy; Lavernia, Enrique J.; Blue, Craig A.; Graeve, Olivia A.; Bayles, Robert; Perepezko, John H.; Kaufman, Larry; Schoenung, Julie; Ajdelsztajn, Leo

    2009-11-17

    A system for coating a surface comprises providing a source of amorphous metal, providing ceramic particles, and applying the amorphous metal and the ceramic particles to the surface by a spray. The coating comprises a composite material made of amorphous metal that contains one or more of the following elements in the specified range of composition: yttrium (.gtoreq.1 atomic %), chromium (14 to 18 atomic %), molybdenum (.gtoreq.7 atomic %), tungsten (.gtoreq.1 atomic %), boron (.ltoreq.5 atomic %), or carbon (.gtoreq.4 atomic %).

  3. Corrosion resistant amorphous metals and methods of forming corrosion resistant amorphous metals

    DOE Patents [OSTI]

    Farmer, Joseph C.; Wong, Frank M.G.; Haslam, Jeffery J.; Yang, Nancy; Lavernia, Enrique J.; Blue, Craig A.; Graeve, Olivia A.; Bayles, Robert; Perepezko, John H.; Kaufman, Larry; Schoenung, Julie; Ajdelsztajn, Leo

    2014-07-15

    A system for coating a surface comprises providing a source of amorphous metal, providing ceramic particles, and applying the amorphous metal and the ceramic particles to the surface by a spray. The coating comprises a composite material made of amorphous metal that contains one or more of the following elements in the specified range of composition: yttrium (.gtoreq.1 atomic %), chromium (14 to 18 atomic %), molybdenum (.gtoreq.7 atomic %), tungsten (.gtoreq.1 atomic %), boron (.ltoreq.5 atomic %), or carbon (.gtoreq.4 atomic %).

  4. Solar Silicon Wafers

    Office of Energy Efficiency and Renewable Energy (EERE)

    This photograph features Hao-Chih Yuan, a scientist at the National Renewable Energy Laboratory (NREL). He is reflected in a highly reflective untreated silicone wafer (left) compared to a silicone...

  5. Silicon solar cell assembly

    DOE Patents [OSTI]

    Burgess, Edward L.; Nasby, Robert D.; Schueler, Donald G.

    1979-01-01

    A silicon solar cell assembly comprising a large, thin silicon solar cell bonded to a metal mount for use when there exists a mismatch in the thermal expansivities of the device and the mount.

  6. Process for producing silicon

    DOE Patents [OSTI]

    Olson, Jerry M. (Lakewood, CO); Carleton, Karen L. (Boulder, CO)

    1984-01-01

    A process for producing silicon includes forming an alloy of copper and silicon and positioning the alloy in a dried, molten salt electrolyte to form a solid anode structure therein. An electrically conductive cathode is placed in the electrolyte for plating silicon thereon. The electrolyte is then purified to remove dissolved oxides. Finally, an electrical potential is applied between the anode and cathode in an amount sufficient to form substantially pure silicon on the cathode in the form of substantially dense, coherent deposits.

  7. Process for producing silicon

    DOE Patents [OSTI]

    Olson, J.M.; Carleton, K.L.

    1982-06-10

    A process of producing silicon includes forming an alloy of copper and silicon and positioning the alloy in a dried, molten salt electrolyte to form a solid anode structure therein. An electrically conductive cathode is placed in the electrolyte for plating silicon thereon. The electrolyte is then purified to remove dissolved oxides. Finally, an electrical potential is applied between the anode and cathode in an amount sufficient to form substantially pure silicon on the cathode in the form of substantially dense, coherent deposits.

  8. Electrodeposition of molten silicon

    DOE Patents [OSTI]

    De Mattei, Robert C.; Elwell, Dennis; Feigelson, Robert S.

    1981-01-01

    Silicon dioxide is dissolved in a molten electrolytic bath, preferably comprising barium oxide and barium fluoride. A direct current is passed between an anode and a cathode in the bath to reduce the dissolved silicon dioxide to non-alloyed silicon in molten form, which is removed from the bath.

  9. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    DOE Patents [OSTI]

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  10. Nanocrystalline SiC formed by annealing of a-SiC:H on Si substrates: A study of dopant interdiffusion

    SciTech Connect (OSTI)

    Schnabel, Manuel; Weiss, Charlotte; Löper, Philipp; Janz, Stefan; Canino, Mariaconcetta; Summonte, Caterina; Wilshaw, Peter R.

    2014-07-14

    Nanocrystalline silicon carbide (nc-SiC) is an interesting material for electronics applications, both in its own right and as a host matrix for silicon quantum dots. When synthesized by annealing of a-SiC:H on Si substrates, interdiffusion of dopants occurs if either the a-SiC:H or the Si substrate is doped. Annealing a-SiC:H on highly boron-doped substrates at 1100 °C leads to a fairly homogeneous doping level of ≥4 × 10{sup 19} cm{sup −3} throughout the nc-SiC film. An unexpected anomaly in secondary ion mass spectroscopy quantification is observed and a method to circumvent it is shown. The nanostructure of the nc-SiC is only weakly affected as most of the diffusion occurs after the onset of crystallization. Annealing of doped a-SiC:H on Si substrates at 1100 °C leads to strong free carrier absorption at infrared wavelengths. This is demonstrated to originate from dopants that have diffused from the a-SiC:H to the Si substrate, and a method is developed to extract from it the doping profile in the Si substrate. The detection limit of this method is estimated to be ≤6 × 10{sup 13} cm{sup −2}. Doping levels of (0.5–3.5) × 10{sup 19} cm{sup −3} are induced at the Si substrate surface by both boron and phosphorus-doped a–SiC:H. When the Si substrate is doped opposite to the a-SiC:H p–n junctions are induced at a depth of 0.9–1.4 μm within the Si substrate for substrate resistivities of 1–10 Ω cm. Implications for different solar cell architectures are discussed. Dopant diffusion can be strongly reduced by lowering the annealing temperature to 1000 °C, albeit at the expense of reduced crystallinity.

  11. Method of making selective crystalline silicon regions containing entrapped hydrogen by laser treatment

    DOE Patents [OSTI]

    Pankove, J.I.; Wu, C.P.

    1982-03-30

    A novel hydrogen rich single crystalline silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystalline silicon without out-gassing the hydrogen. The new material can be used to fabricate semi-conductor devices such as single crystalline silicon solar cells with surface window regions having a greater band gap energy than that of single crystalline silicon without hydrogen. 2 figs.

  12. Glass-silicon column

    DOE Patents [OSTI]

    Yu, Conrad M.

    2003-12-30

    A glass-silicon column that can operate in temperature variations between room temperature and about 450.degree. C. The glass-silicon column includes large area glass, such as a thin Corning 7740 boron-silicate glass bonded to a silicon wafer, with an electrode embedded in or mounted on glass of the column, and with a self alignment silicon post/glass hole structure. The glass/silicon components are bonded, for example be anodic bonding. In one embodiment, the column includes two outer layers of silicon each bonded to an inner layer of glass, with an electrode imbedded between the layers of glass, and with at least one self alignment hole and post arrangement. The electrode functions as a column heater, and one glass/silicon component is provided with a number of flow channels adjacent the bonded surfaces.

  13. Controlled epitaxial graphene growth within removable amorphous carbon corrals

    SciTech Connect (OSTI)

    Palmer, James; Hu, Yike; Hankinson, John; Guo, Zelei; Heer, Walt A. de; Kunc, Jan; Berger, Claire

    2014-07-14

    We address the question of control of the silicon carbide (SiC) steps and terraces under epitaxial graphene on SiC and demonstrate amorphous carbon (aC) corrals as an ideal method to pin SiC surface steps. aC is compatible with graphene growth, structurally stable at high temperatures, and can be removed after graphene growth. For this, aC is first evaporated and patterned on SiC, then annealed in the graphene growth furnace. There at temperatures above 1200?C, mobile SiC steps accumulate at the aC corral that provide effective step flow barriers. Aligned step free regions are thereby formed for subsequent graphene growth at temperatures above 1330?C. Atomic force microscopy imaging supports the formation of step-free terraces on SiC with the step morphology aligned to the aC corrals. Raman spectroscopy indicates the presence of good graphene sheets on the step-free terraces.

  14. Structure and Reactivity of X-ray Amorphous Uranyl Peroxide,...

    Office of Scientific and Technical Information (OSTI)

    Published Article: Structure and Reactivity of X-ray Amorphous Uranyl Peroxide, U 2 O 7 Prev Next Title: Structure and Reactivity of X-ray Amorphous Uranyl Peroxide, U 2 O 7 ...

  15. Type I clathrates as novel silicon anodes: An electrochemical and structural investigation

    SciTech Connect (OSTI)

    Li, Ying; Raghavan, Rahul; Wagner, Nicholas A.; Davidowski, Stephen K.; Baggetto, Loic; Zhao, Ran; Cheng, Qian; Yarger, Jeffery L.; Veith, Gabriel M.; Ellis-Terrell, Carol; Miller, Michael A.; Chan, Kwai S.; Chan, Candace K.

    2015-05-05

    In this study, silicon clathrates contain cage-like structures that can encapsulate various guest atoms or molecules. Here we present an electrochemical evaluation of type I silicon clathrates based on Ba8AlySi46-y for the anode material in lithium-ion batteries. Post-cycling characterization with NMR and XRD show no discernible structural or volume changes even after electrochemical insertion of 44 Li into the clathrate structure. The observed properties are in stark contrast with lithiation of other silicon anodes, which become amorphous and suffer from larger volume changes. The lithiation/delithiation processes are proposed to occur in single phase reactions at approximately 0.2 and 0.4 V vs. Li/Li+, respectively, distinct from other diamond cubic or amorphous silicon anodes. Reversible capacities as high as 499 mAh g-1 at a 5 mA g-1 rate were observed for silicon clathrate with composition Ba8Al8.54Si37.46, corresponding to Li:Si of 1.18:1. The results show that silicon clathrates could be promising durable anodes for lithium-ion batteries.

  16. Type I clathrates as novel silicon anodes: An electrochemical and structural investigation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Ying; Raghavan, Rahul; Wagner, Nicholas A.; Davidowski, Stephen K.; Baggetto, Loic; Zhao, Ran; Cheng, Qian; Yarger, Jeffery L.; Veith, Gabriel M.; Ellis-Terrell, Carol; et al

    2015-05-05

    In this study, silicon clathrates contain cage-like structures that can encapsulate various guest atoms or molecules. Here we present an electrochemical evaluation of type I silicon clathrates based on Ba8AlySi46-y for the anode material in lithium-ion batteries. Post-cycling characterization with NMR and XRD show no discernible structural or volume changes even after electrochemical insertion of 44 Li into the clathrate structure. The observed properties are in stark contrast with lithiation of other silicon anodes, which become amorphous and suffer from larger volume changes. The lithiation/delithiation processes are proposed to occur in single phase reactions at approximately 0.2 and 0.4 Vmore » vs. Li/Li+, respectively, distinct from other diamond cubic or amorphous silicon anodes. Reversible capacities as high as 499 mAh g-1 at a 5 mA g-1 rate were observed for silicon clathrate with composition Ba8Al8.54Si37.46, corresponding to Li:Si of 1.18:1. The results show that silicon clathrates could be promising durable anodes for lithium-ion batteries.« less

  17. Plasma deposition of amorphous metal alloys

    DOE Patents [OSTI]

    Hays, Auda K. (Albuquerque, NM)

    1986-01-01

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  18. Plasma deposition of amorphous metal alloys

    DOE Patents [OSTI]

    Hays, A.K.

    1979-07-18

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  19. Silicon micro-mold

    DOE Patents [OSTI]

    Morales, Alfredo M.

    2006-10-24

    The present invention describes a method for rapidly fabricating a robust 3-dimensional silicon-mold for use in preparing complex metal micro-components. The process begins by depositing a conductive metal layer onto one surface of a silicon wafer. A thin photoresist and a standard lithographic mask are then used to transfer a trace image pattern onto the opposite surface of the wafer by exposing and developing the resist. The exposed portion of the silicon substrate is anisotropically etched through the wafer thickness down to conductive metal layer to provide an etched pattern consisting of a series of rectilinear channels and recesses in the silicon which serve as the silicon micro-mold. Microcomponents are prepared with this mold by first filling the mold channels and recesses with a metal deposit, typically by electroplating, and then removing the silicon micro-mold by chemical etching.

  20. Cathode encapsulation of organic light emitting diodes by atomic layer deposited Al{sub 2}O{sub 3} films and Al{sub 2}O{sub 3}/a-SiN{sub x}:H stacks

    SciTech Connect (OSTI)

    Keuning, W.; Weijer, P. van de; Lifka, H.; Kessels, W. M. M.; Creatore, M. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Philips Research Laboratories, High Tech Campus 4, P.O. Box WAG12, 5656 AE Eindhoven (Netherlands); Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2012-01-15

    Al{sub 2}O{sub 3} thin films synthesized by plasma-enhanced atomic layer deposition (ALD) at room temperature (25 deg. C) have been tested as water vapor permeation barriers for organic light emitting diode devices. Silicon nitride films (a-SiN{sub x}:H) deposited by plasma-enhanced chemical vapor deposition served as reference and were used to develop Al{sub 2}O{sub 3}/a-SiN{sub x}:H stacks. On the basis of Ca test measurements, a very low intrinsic water vapor transmission rate of {<=} 2 x 10{sup -6} g m{sup -2} day{sup -1} and 4 x 10{sup -6} g m{sup -2} day{sup -1} (20 deg. C/50% relative humidity) were found for 20-40 nm Al{sub 2}O{sub 3} and 300 nm a-SiN{sub x}:H films, respectively. The cathode particle coverage was a factor of 4 better for the Al{sub 2}O{sub 3} films compared to the a-SiN{sub x}:H films and an average of 0.12 defects per cm{sup 2} was obtained for a stack consisting of three barrier layers (Al{sub 2}O{sub 3}/a-SiN{sub x}:H/Al{sub 2}O{sub 3}).

  1. Thermally Oxidized Silicon

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    4 Anneli Munkholm (Lumileds Lighting) and Sean Brennan (SSRL) Illustration of the silicon positions near the Si-SiO2 interface for a 4° miscut projected onto the ( ) plane. The silicon atoms in the substrate are blue and those in the oxide are red. The small black spots represent the translated silicon positions in the absence of static disorder. The silicon atoms in the oxide have been randomly assigned a magnitude and direction based on the static disorder value at that position in the

  2. Micromachined silicon electrostatic chuck

    DOE Patents [OSTI]

    Anderson, R.A.; Seager, C.H.

    1996-12-10

    An electrostatic chuck is faced with a patterned silicon plate, created by micromachining a silicon wafer, which is attached to a metallic base plate. Direct electrical contact between the chuck face (patterned silicon plate`s surface) and the silicon wafer it is intended to hold is prevented by a pattern of flat-topped silicon dioxide islands that protrude less than 5 micrometers from the otherwise flat surface of the chuck face. The islands may be formed in any shape. Islands may be about 10 micrometers in diameter or width and spaced about 100 micrometers apart. One or more concentric rings formed around the periphery of the area between the chuck face and wafer contain a low-pressure helium thermal-contact gas used to assist heat removal during plasma etching of a silicon wafer held by the chuck. The islands are tall enough and close enough together to prevent silicon-to-silicon electrical contact in the space between the islands, and the islands occupy only a small fraction of the total area of the chuck face, typically 0.5 to 5 percent. The pattern of the islands, together with at least one hole bored through the silicon veneer into the base plate, will provide sufficient gas-flow space to allow the distribution of the helium thermal-contact gas. 6 figs.

  3. Micromachined silicon electrostatic chuck

    DOE Patents [OSTI]

    Anderson, Robert A.; Seager, Carleton H.

    1996-01-01

    An electrostatic chuck is faced with a patterned silicon plate 11, created y micromachining a silicon wafer, which is attached to a metallic base plate 13. Direct electrical contact between the chuck face 15 (patterned silicon plate's surface) and the silicon wafer 17 it is intended to hold is prevented by a pattern of flat-topped silicon dioxide islands 19 that protrude less than 5 micrometers from the otherwise flat surface of the chuck face 15. The islands 19 may be formed in any shape. Islands may be about 10 micrometers in diameter or width and spaced about 100 micrometers apart. One or more concentric rings formed around the periphery of the area between the chuck face 15 and wafer 17 contain a low-pressure helium thermal-contact gas used to assist heat removal during plasma etching of a silicon wafer held by the chuck. The islands 19 are tall enough and close enough together to prevent silicon-to-silicon electrical contact in the space between the islands, and the islands occupy only a small fraction of the total area of the chuck face 15, typically 0.5 to 5 percent. The pattern of the islands 19, together with at least one hole 12 bored through the silicon veneer into the base plate, will provide sufficient gas-flow space to allow the distribution of the helium thermal-contact gas.

  4. Theoretical investigations of defects in a Si-based digital ferromagne...

    Office of Scientific and Technical Information (OSTI)

    digital ferromagnetic heterostructure - a spintronic material Citation Details In-Document Search Title: Theoretical investigations of defects in a Si-based digital ...

  5. Silicone-containing composition

    DOE Patents [OSTI]

    Mohamed, Mustafa

    2012-01-24

    A silicone-containing composition comprises the reaction product of a first component and an excess of an isocyanate component relative to the first component to form an isocyanated intermediary. The first component is selected from one of a polysiloxane and a silicone resin. The first component includes a carbon-bonded functional group selected from one of a hydroxyl group and an amine group. The isocyanate component is reactive with the carbon-bonded functional group of the first component. The isocyanated intermediary includes a plurality of isocyanate functional groups. The silicone-containing composition comprises the further reaction product of a second component, which is selected from the other of the polysiloxane and the silicone resin. The second component includes a plurality of carbon-bonded functional groups reactive with the isocyanate functional groups of the isocyanated intermediary for preparing the silicone-containing composition.

  6. Reversibility and criticality in amorphous solids

    SciTech Connect (OSTI)

    Regev, Ido; Weber, John; Reichhardt, Charles; Dahmen, Karin A.; Lookman, Turab

    2015-11-13

    The physical processes governing the onset of yield, where a material changes its shape permanently under external deformation, are not yet understood for amorphous solids that are intrinsically disordered. Here, using molecular dynamics simulations and mean-field theory, we show that at a critical strain amplitude the sizes of clusters of atoms undergoing cooperative rearrangements of displacements (avalanches) diverges. We compare this non-equilibrium critical behaviour to the prevailing concept of a ‘front depinning’ transition that has been used to describe steady-state avalanche behaviour in different materials. We explain why a depinning-like process can result in a transition from periodic to chaotic behaviour and why chaotic motion is not possible in pinned systems. As a result, these findings suggest that, at least for highly jammed amorphous systems, the irreversibility transition may be a side effect of depinning that occurs in systems where the disorder is not quenched.

  7. Reversibility and criticality in amorphous solids

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Regev, Ido; Weber, John; Reichhardt, Charles; Dahmen, Karin A.; Lookman, Turab

    2015-11-13

    The physical processes governing the onset of yield, where a material changes its shape permanently under external deformation, are not yet understood for amorphous solids that are intrinsically disordered. Here, using molecular dynamics simulations and mean-field theory, we show that at a critical strain amplitude the sizes of clusters of atoms undergoing cooperative rearrangements of displacements (avalanches) diverges. We compare this non-equilibrium critical behaviour to the prevailing concept of a ‘front depinning’ transition that has been used to describe steady-state avalanche behaviour in different materials. We explain why a depinning-like process can result in a transition from periodic to chaoticmore » behaviour and why chaotic motion is not possible in pinned systems. As a result, these findings suggest that, at least for highly jammed amorphous systems, the irreversibility transition may be a side effect of depinning that occurs in systems where the disorder is not quenched.« less

  8. Germanium detector passivated with hydrogenated amorphous germanium

    DOE Patents [OSTI]

    Hansen, William L.; Haller, Eugene E.

    1986-01-01

    Passivation of predominantly crystalline semiconductor devices (12) is provided for by a surface coating (21) of sputtered hydrogenated amorphous semiconductor material. Passivation of a radiation detector germanium diode, for example, is realized by sputtering a coating (21) of amorphous germanium onto the etched and quenched diode surface (11) in a low pressure atmosphere of hydrogen and argon. Unlike prior germanium diode semiconductor devices (12), which must be maintained in vacuum at cryogenic temperatures to avoid deterioration, a diode processed in the described manner may be stored in air at room temperature or otherwise exposed to a variety of environmental conditions. The coating (21) compensates for pre-existing undesirable surface states as well as protecting the semiconductor device (12) against future impregnation with impurities.

  9. Synthesis of new amorphous metallic spin glasses

    DOE Patents [OSTI]

    Haushalter, R.C.

    1985-02-11

    Disclosed are: amorphous metallic precipitates having the formula (M/sub 1/)/sub a/(M/sub 2/)/sub b/ wherein M/sub 1/ is at least one transition metal, M/sub 2/ is at least one main group metal and the integers ''a'' and ''b'' provide stoichiometric balance; the precipitates having a degree of local order characteristic of chemical compounds from the precipitation process and useful electrical and mechanical properties.

  10. Synthesis of new amorphous metallic spin glasses

    DOE Patents [OSTI]

    Haushalter, Robert C.

    1988-01-01

    Amorphous metallic precipitates having the formula (M.sub.1).sub.a (M.sub.2).sub.b wherein M.sub.1 is at least one transition metal, M.sub.2 is at least one main group metal and the integers "a" and "b" provide stoichiometric balance; the precipitates having a degree of local order characteristic of chemical compounds from the precipitation process and useful electrical and mechanical properties.

  11. Synthesis of new amorphous metallic spin glasses

    DOE Patents [OSTI]

    Haushalter, Robert C.

    1986-01-01

    Amorphous metallic precipitates having the formula (M.sub.1).sub.a (M.sub.2).sub.b wherein M.sub.1 is at least one transition metal, M.sub.2 is at least one main group metal and the integers "a" and "b" provide stoichiometric balance; the precipitates having a degree of local order characteristic of chemical compounds from the precipitation process and useful electrical and mechanical properties.

  12. Structure, defects, and strain in silicon-silicon oxide interfaces

    SciTech Connect (OSTI)

    Kova?evi?, Goran Pivac, Branko

    2014-01-28

    The structure of the interfaces between silicon and silicon-oxide is responsible for proper functioning of MOSFET devices while defects in the interface can deteriorate this function and lead to their failure. In this paper we modeled this interface and characterized its defects and strain. MD simulations were used for reconstructing interfaces into a thermodynamically stable configuration. In all modeled interfaces, defects were found in the form of three-coordinated silicon atom, five coordinated silicon atom, threefold-coordinated oxygen atom, or displaced oxygen atom. Three-coordinated oxygen atom can be created if dangling bonds on silicon are close enough. The structure and stability of three-coordinated silicon atoms (P{sub b} defect) depend on the charge as well as on the electric field across the interface. The negatively charged P{sub b} defect is the most stable one, but the electric field resulting from the interface reduces that stability. Interfaces with large differences in periodic constants of silicon and silicon oxide can be stabilized by buckling of silicon layer. The mechanical stress resulted from the interface between silicon and silicon oxide is greater in the silicon oxide layer. Ab initio modeling of clusters representing silicon and silicon oxide shows about three time larger susceptibility to strain in silicon oxide than in silicon if exposed to the same deformation.

  13. Method for producing silicon nitride/silicon carbide composite

    DOE Patents [OSTI]

    Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

    1996-07-23

    Silicon carbide/silicon nitride composites are prepared by carbothermal reduction of crystalline silica powder, carbon powder and optionally crsytalline silicon nitride powder. The crystalline silicon carbide portion of the composite has a mean number diameter less than about 700 nanometers and contains nitrogen.

  14. Solar cells utilizing pulsed-energy crystallized microcrystalline/polycrystalline silicon

    DOE Patents [OSTI]

    Kaschmitter, James L. (Pleasanton, CA); Sigmon, Thomas W. (Beaverton, OR)

    1995-01-01

    A process for producing multi-terminal devices such as solar cells wherein a pulsed high energy source is used to melt and crystallize amorphous silicon deposited on a substrate which is intolerant to high processing temperatures, whereby to amorphous silicon is converted into a microcrystalline/polycrystalline phase. Dopant and hydrogenization can be added during the fabrication process which provides for fabrication of extremely planar, ultra shallow contacts which results in reduction of non-current collecting contact volume. The use of the pulsed energy beams results in the ability to fabricate high efficiency microcrystalline/polycrystalline solar cells on the so-called low-temperature, inexpensive plastic substrates which are intolerant to high processing temperatures.

  15. Solar cells utilizing pulsed-energy crystallized microcrystalline/polycrystalline silicon

    DOE Patents [OSTI]

    Kaschmitter, J.L.; Sigmon, T.W.

    1995-10-10

    A process for producing multi-terminal devices such as solar cells wherein a pulsed high energy source is used to melt and crystallize amorphous silicon deposited on a substrate which is intolerant to high processing temperatures, whereby the amorphous silicon is converted into a microcrystalline/polycrystalline phase. Dopant and hydrogenation can be added during the fabrication process which provides for fabrication of extremely planar, ultra shallow contacts which results in reduction of non-current collecting contact volume. The use of the pulsed energy beams results in the ability to fabricate high efficiency microcrystalline/polycrystalline solar cells on the so-called low-temperature, inexpensive plastic substrates which are intolerant to high processing temperatures.

  16. Porous silicon gettering

    SciTech Connect (OSTI)

    Tsuo, Y.S.; Menna, P.; Pitts, J.R.

    1996-05-01

    The authors have studied a novel extrinsic gettering method that uses the large surface areas produced by a porous-silicon etch as gettering sites. The annealing step of the gettering used a high-flux solar furnace. They found that a high density of photons during annealing enhanced the impurity diffusion to the gettering sites. The authors used metallurgical-grade Si (MG-Si) prepared by directional solidification casing as the starting material. They propose to use porous-silicon-gettered MG-Si as a low-cost epitaxial substrate for polycrystalline silicon thin-film growth.

  17. Polycrystalline silicon passivated tunneling contacts for high...

    Office of Scientific and Technical Information (OSTI)

    efficiency silicon solar cells Citation Details In-Document Search Title: Polycrystalline silicon passivated tunneling contacts for high efficiency silicon solar cells Authors: ...

  18. Longi Silicon Materials Corp | Open Energy Information

    Open Energy Info (EERE)

    Longi Silicon Materials Corp Jump to: navigation, search Name: Longi Silicon Materials Corp Place: Xi'an, Shaanxi Province, China Zip: 710065 Product: A monocrystalline silicon...

  19. Photovoltaic Crystalline Silicon Cell Basics | Department of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Crystalline Silicon Cell Basics Photovoltaic Crystalline Silicon Cell Basics August 20, 2013 - 2:00pm Addthis To separate electrical charges, crystalline silicon cells must have a ...

  20. Enabling Thin Silicon Solar Cell Technology

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Enabling Thin Silicon Solar Cell Technology Enabling Thin Silicon Solar Cell Technology Print Friday, 21 June 2013 10:49 Generic silicon solar cells showing +45, -45, and ...

  1. Tangshan Silicon Co Ltd | Open Energy Information

    Open Energy Info (EERE)

    search Name: Tangshan Silicon Co Ltd Place: Tangshan, Hebei Province, China Product: Chinese silicon producer developing a 1000t silicon plant in Tangshan, Hebei Province. It has...

  2. Researchers examine behavior of amorphous materials under high strain

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Behavior of amorphous materials under high strain Researchers examine behavior of amorphous materials under high strain The findings offer a new way to monitor the onset of plastic deformation and mechanical properties of materials. February 10, 2016 Shown is simulation of a reversible avalanche in an amorphous solid under a periodic shear. Darker regions indicate where particles have been displaced more. The motion is exactly repeated during the next drive cycle. Above a critical strain, the

  3. Polyamorphous transition in amorphous fullerites C{sub 70}

    SciTech Connect (OSTI)

    Borisova, P. A.; Agafonov, S. S.; Glazkov, V. P.; D'yakonova, N. P.; Somenkov, V. A.

    2011-12-15

    Samples of amorphous fullerites C{sub 70} have been obtained by mechanical activation (grinding in a ball mill). The structure of the samples has been investigated by neutron and X-ray diffraction. The high-temperature (up to 1200 Degree-Sign C) annealing of amorphous fullerites revealed a polyamorphous transition from molecular to atomic glass, which is accompanied by the disappearance of fullerene halos at small scattering angles. Possible structural versions of the high-temperature amorphous phase are discussed.

  4. Sulfur-impurity Induced Amorphization of Nickel | Argonne Leadership

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Computing Facility Sulfur-impurity Induced Amorphization of Nickel Authors: Yuan, Z., Chen, H.P, Wang, W., Nomura, K., Kalia, R.K., Nakano, A., Vashishta, P. Recent experimental and theoretical studies have shown an essential role of sulfur segregation-induced amorphization of crystalline nickel leading to its embrittlement at a critical sulfur concentration of ∼14%, but the atomistic mechanism of the amorphization remains unexplained. Here, molecular dynamics simulations reveal that the

  5. Order, disorder and mixing: The atomic structure of amorphous...

    Office of Scientific and Technical Information (OSTI)

    Order, disorder and mixing: The atomic structure of amorphous mixtures of titania and tantala Citation Details In-Document Search Title: Order, disorder and mixing: The atomic ...

  6. Molecular Dynamics Simulations of Gas Selectivity in Amorphous...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Dynamics Simulations of Gas Selectivity in Amorphous Porous Molecular Solids Previous Next List Shan Jiang, Kim E. Jelfs, Daniel Holden, Tom Hasell, Samantha Y. Chong, Maciej...

  7. The origins of growth stresses in amorphous semiconductor thin...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: The origins of growth stresses in amorphous semiconductor thin films. Citation Details In-Document ... Publication Date: 2003-03-01 OSTI Identifier: 917484 Report ...

  8. Amorphous carbon film growth on Si: Correlation between stress and generation of defects into the substrate

    SciTech Connect (OSTI)

    Brusa, R.S.; Macchi, C.; Mariazzi, S.; Karwasz, G.P.; Laidani, N.; Bartali, R.; Anderle, M.

    2005-05-30

    Amorphous carbon films of several thicknesses were prepared by graphite sputtering on crystalline silicon substrate. The samples were depth profiled with positron annihilation spectroscopy for open-volume measurements and characterized for their residual internal stress. It was found that after film growth the substrate presents vacancy-like defects decorated by oxygen in a layer extending in the substrate by several tens of nanometers beyond the film/Si interface. The width of the defected layer and the decoration of vacancy-like defects are directly and inversely proportional to the measured intensity of the residual stress, respectively. These findings indicate the existence of a relaxation mechanism of the stress in the films that involves deeply the substrate. The decorated vacancy-like defects are suggested to be bounded to dislocations induced in the substrate by the stress relaxation.

  9. Monolithic Composite Electrodes Comprising Silicon Nanoparticles...

    Office of Scientific and Technical Information (OSTI)

    Monolithic Composite Electrodes Comprising Silicon Nanoparticles Embedded in ... Title: Monolithic Composite Electrodes Comprising Silicon Nanoparticles Embedded in ...

  10. Salt Fog Testing Iron-Based Amorphous Alloys

    SciTech Connect (OSTI)

    Rebak, Raul B.; Aprigliano, Louis F.; Day, S. Daniel; Farmer, Joseph C.

    2007-07-01

    Iron-based amorphous alloys are hard and highly corrosion resistant, which make them desirable for salt water and other applications. These alloys can be produced as powder and can be deposited as coatings on any surface that needs to be protected from the environment. It was of interest to examine the behavior of these amorphous alloys in the standard salt-fog testing ASTM B 117. Three different amorphous coating compositions were deposited on 316L SS coupons and exposed for many cycles of the salt fog test. Other common engineering alloys such as 1018 carbon steel, 316L SS and Hastelloy C-22 were also tested together with the amorphous coatings. Results show that amorphous coatings are resistant to rusting in salt fog. Partial devitrification may be responsible for isolated rust spots in one of the coatings. (authors)

  11. Silicon Cells | Open Energy Information

    Open Energy Info (EERE)

    a low cost method of processing silicon to produce a new generation of high energy density batteries. References: Silicon Cells1 This article is a stub. You can help OpenEI...

  12. Floating Silicon Method

    SciTech Connect (OSTI)

    Kellerman, Peter

    2013-12-21

    The Floating Silicon Method (FSM) project at Applied Materials (formerly Varian Semiconductor Equipment Associates), has been funded, in part, by the DOE under a “Photovoltaic Supply Chain and Cross Cutting Technologies” grant (number DE-EE0000595) for the past four years. The original intent of the project was to develop the FSM process from concept to a commercially viable tool. This new manufacturing equipment would support the photovoltaic industry in following ways: eliminate kerf losses and the consumable costs associated with wafer sawing, allow optimal photovoltaic efficiency by producing high-quality silicon sheets, reduce the cost of assembling photovoltaic modules by creating large-area silicon cells which are free of micro-cracks, and would be a drop-in replacement in existing high efficiency cell production process thereby allowing rapid fan-out into the industry.

  13. Atomic Sandblasters Could Replace Silicon

    Broader source: Energy.gov [DOE]

    Scientists at the National Labs may have found a cheaper, lighter more efficient replacement for silicon in computer chips.

  14. Room-temperature near-infrared silicon carbide nanocrystalline emitters based on optically aligned spin defects

    SciTech Connect (OSTI)

    Muzha, A.; Fuchs, F.; Simin, D.; Astakhov, G. V.; Tarakina, N. V.; Trupke, M.; Soltamov, V. A.; Mokhov, E. N.; Baranov, P. G.; Dyakonov, V.; and others

    2014-12-15

    Bulk silicon carbide (SiC) is a very promising material system for bio-applications and quantum sensing. However, its optical activity lies beyond the near infrared spectral window for in-vivo imaging and fiber communications due to a large forbidden energy gap. Here, we report the fabrication of SiC nanocrystals and isolation of different nanocrystal fractions ranged from 600?nm down to 60?nm in size. The structural analysis reveals further fragmentation of the smallest nanocrystals into ca. 10-nm-size clusters of high crystalline quality, separated by amorphization areas. We use neutron irradiation to create silicon vacancies, demonstrating near infrared photoluminescence. Finally, we detect room-temperature spin resonances of these silicon vacancies hosted in SiC nanocrystals. This opens intriguing perspectives to use them not only as in-vivo luminescent markers but also as magnetic field and temperature sensors, allowing for monitoring various physical, chemical, and biological processes.

  15. Electrochemical thinning of silicon

    DOE Patents [OSTI]

    Medernach, John W.

    1994-01-01

    Porous semiconducting material, e.g. silicon, is formed by electrochemical treatment of a specimen in hydrofluoric acid, using the specimen as anode. Before the treatment, the specimen can be masked. The porous material is then etched with a caustic solution or is oxidized, depending of the kind of structure desired, e.g. a thinned specimen, a specimen, a patterned thinned specimen, a specimen with insulated electrical conduits, and so on. Thinned silicon specimen can be subjected to tests, such as measurement of interstitial oxygen by Fourier transform infra-red spectroscopy (FTIR).

  16. Electrochemical thinning of silicon

    DOE Patents [OSTI]

    Medernach, J.W.

    1994-01-11

    Porous semiconducting material, e.g. silicon, is formed by electrochemical treatment of a specimen in hydrofluoric acid, using the specimen as anode. Before the treatment, the specimen can be masked. The porous material is then etched with a caustic solution or is oxidized, depending of the kind of structure desired, e.g. a thinned specimen, a specimen, a patterned thinned specimen, a specimen with insulated electrical conduits, and so on. Thinned silicon specimen can be subjected to tests, such as measurement of interstitial oxygen by Fourier transform infra-red spectroscopy (FTIR). 14 figures.

  17. Bulk amorphous steels based on Fe alloys

    DOE Patents [OSTI]

    Lu, ZhaoPing; Liu, Chain T.

    2006-05-30

    A bulk amorphous alloy has the approximate composition: Fe.sub.(100-a-b-c-d-e)Y.sub.aMn.sub.bT.sub.cM.sub.dX.sub.e wherein: T includes at least one of the group consisting of: Ni, Cu, Cr and Co; M includes at least one of the group consisting of W, Mo, Nb, Ta, Al and Ti; X includes at least one of the group consisting of Co, Ni and Cr; a is an atomic percentage, and a<5; b is an atomic percentage, and b.ltoreq.25; c is an atomic percentage, and c.ltoreq.25; d is an atomic percentage, and d.ltoreq.25; and e is an atomic percentage, and 5.ltoreq.e.ltoreq.30.

  18. Polaron absorption in amorphous tungsten oxide films

    SciTech Connect (OSTI)

    Berggren, Lars; Azens, Andris; Niklasson, Gunnar A.

    2001-08-15

    Amorphous thin films of tungsten oxide were deposited by sputtering onto glass substrates covered by conductive indium--tin oxide. The density and stoichiometry were determined by Rutherford backscattering spectrometry. Lithium ions were intercalated electrochemically into the films. The optical reflectance and transmittance were measured in the wavelength range from 0.3 to 2.5 {mu}m, at a number of intercalation levels. The polaron absorption peak becomes more symmetric and shifts to higher energies until an intercalation level of 0.25 to 0.3 Li{sup +}/W, where a saturation occurs. The shape of the polaron peak is in very good agreement with the theory of Bryksin [Fiz. Tverd. Tela 24, 1110 (1982)]. Within this model, the shift of the absorption peak is interpreted as an increase in the Fermi level of the material as more Li ions are inserted. {copyright} 2001 American Institute of Physics.

  19. Use of additives to improve microstructures and fracture resistance of silicon nitride ceramics

    DOE Patents [OSTI]

    Becher, Paul F.; Lin, Hua-Tay

    2011-06-28

    A high-strength, fracture-resistant silicon nitride ceramic material that includes about 5 to about 75 wt-% of elongated reinforcing grains of beta-silicon nitride, about 20 to about 95 wt-% of fine grains of beta-silicon nitride, wherein the fine grains have a major axis of less than about 1 micron; and about 1 to about 15 wt-% of an amorphous intergranular phase comprising Si, N, O, a rare earth element and a secondary densification element. The elongated reinforcing grains have an aspect ratio of 2:1 or greater and a major axis measuring about 1 micron or greater. The elongated reinforcing grains are essentially isotropically oriented within the ceramic microstructure. The silicon nitride ceramic exhibits a room temperature flexure strength of 1,000 MPa or greater and a fracture toughness of 9 MPa-m.sup.(1/2) or greater. The silicon nitride ceramic exhibits a peak strength of 800 MPa or greater at 1200 degrees C. Also included are methods of making silicon nitride ceramic materials which exhibit the described high flexure strength and fracture-resistant values.

  20. A micron resolution optical scanner for characterization of silicon detectors

    SciTech Connect (OSTI)

    Shukla, R. A.; Dugad, S. R. Gopal, A. V.; Gupta, S. K.; Prabhu, S. S.; Garde, C. S.

    2014-02-15

    The emergence of high position resolution (?10 ?m) silicon detectors in recent times have highlighted the urgent need for the development of new automated optical scanners of micron level resolution suited for characterizing microscopic features of these detectors. More specifically, for the newly developed silicon photo-multipliers (SiPM) that are compact, possessing excellent photon detection efficiency with gain comparable to photo-multiplier tube. In a short time, since their invention the SiPMs are already being widely used in several high-energy physics and astrophysics experiments as the photon readout element. The SiPM is a high quantum efficiency, multi-pixel photon counting detector with fast timing and high gain. The presence of a wide variety of photo sensitive silicon detectors with high spatial resolution requires their performance evaluation to be carried out by photon beams of very compact spot size. We have designed a high resolution optical scanner that provides a monochromatic focused beam on a target plane. The transverse size of the beam was measured by the knife-edge method to be 1.7 ?m at 1 ? ? level. Since the beam size was an order of magnitude smaller than the typical feature size of silicon detectors, this optical scanner can be used for selective excitation of these detectors. The design and operational details of the optical scanner, high precision programmed movement of target plane (0.1 ?m) integrated with general purpose data acquisition system developed for recording static and transient response photo sensitive silicon detector are reported in this paper. Entire functionality of scanner is validated by using it for selective excitation of individual pixels in a SiPM and identifying response of active and dead regions within SiPM. Results from these studies are presented in this paper.

  1. Silicon Carbide Emitter Turn-Off Thyristor

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Jun; Wang, Gangyao; Li, Jun; Huang, Alex Q.; Melcher, Jerry; Atcitty, Stan

    2008-01-01

    A novel MOS-conmore » trolled SiC thyristor device, the SiC emitter turn-off thyristor (ETO) is a promising technology for future high-voltage switching applications because it integrates the excellent current conduction capability of a SiC thyristor with a simple MOS-control interface. Through unity-gain turn-off, the SiC ETO also achieves excellent Safe Operation Area (SOA) and faster switching speeds than silicon ETOs. The world's first 4.5-kV SiC ETO prototype shows a forward voltage drop of 4.26 V at 26.5  A / cm 2 current density at room and elevated temperatures. Tested in an inductive circuit with a 2.5 kV DC link voltage and a 9.56-A load current, the SiC ETO shows a fast turn-off time of 1.63 microseconds and a low 9.88 mJ turn-off energy. The low switching loss indicates that the SiC ETO could operate at about 4 kHz if 100  W / cm 2 conduction and the 100  W / cm 2 turn-off losses can be removed by the thermal management system. This frequency capability is about 4 times higher than 4.5-kV-class silicon power devices. The preliminary demonstration shows that the SiC ETO is a promising candidate for high-frequency, high-voltage power conversion applications, and additional developments to optimize the device for higher voltage (>5 kV) and higher frequency (10 kHz) are needed.« less

  2. New Hydrogen Distribution in {ital a}-Si:H: An NMR Study

    SciTech Connect (OSTI)

    Wu, Y.; Stephen, J.T.; Han, D.X.; Rutland, J.M.; Crandall, R.S.; Mahan, A.H.

    1996-09-01

    Hot-filament-assisted CVD deposited {ital a}-Si:H with low H concentration and low defect density has been examined by {sup 1}H NMR. It is demonstrated for the first time that H microstructures can be altered significantly in device quality {ital a}-Si:H films. In the present films, large H clusters account for 90{percent} of the 2{endash}3 at.{percent} H atoms, with the remaining H more dispersed, but still aggregated in a small volume fraction of the material. These results suggest that an ideal {ital a}-Si:H network with low defect density and high structural stability may not necessarily be homogeneous. {copyright} {ital 1996 The American Physical Society.}

  3. Ambient to high-temperature fracture toughness and cyclic fatigue behavior in Al-containing silicon carbide ceramics

    SciTech Connect (OSTI)

    Yuan, R.; Kruzic, J.J.; Zhang, X.F.; De Jonghe, L.C.; Ritchie, R.O.

    2003-08-01

    A series of in situ toughened, A1, B and C containing, silicon carbide ceramics (ABC-SiC) has been examined with A1 contents varying from 3 to 7 wt percent. With increasing A1 additions, the grain morphology in the as-processed microstructures varied from elongated to bimodal to equiaxed, with a change in the nature of the grain-boundary film from amorphous to partially crystalline to fully crystalline.

  4. High efficiency thin film CdTe and a-Si based solar cells

    SciTech Connect (OSTI)

    Compaan, A. D.; Deng, X.; Bohn, R. G.

    2000-01-04

    This report describes work done by the University of Toledo during the first year of this subcontract. During this time, the CdTe group constructed a second dual magnetron sputter deposition facility; optimized reactive sputtering for ZnTe:N films to achieve 10 ohm-cm resistivity and {approximately}9% efficiency cells with a copper-free ZnTe:N/Ni contact; identified Cu-related photoluminescence features and studied their correlation with cell performance including their dependence on temperature and E-fields; studied band-tail absorption in CdS{sub x}Te{sub 1{minus}x} films at 10 K and 300 K; collaborated with the National CdTe PV Team on (1) studies of high-resistivity tin oxide (HRT) layers from ITN Energy Systems, (2) fabrication of cells on the HRT layers with 0, 300, and 800-nm CdS, and (3) preparation of ZnTe:N-based contacts on First Solar materials for stress testing; and collaborated with Brooklyn College for ellipsometry studies of CdS{sub x}Te{sub 1{minus}x} alloy films, and with the University of Buffalo/Brookhaven NSLS for synchrotron X-ray fluorescence studies of interdiffusion in CdS/CdTe bilayers. The a-Si group established a baseline for fabricating a-Si-based solar cells with single, tandem, and triple-junction structures; fabricated a-Si/a-SiGe/a-SiGe triple-junction solar cells with an initial efficiency of 9.7% during the second quarter, and 10.6% during the fourth quarter (after 1166 hours of light-soaking under 1-sun light intensity at 50 C, the 10.6% solar cells stabilized at about 9%); fabricated wide-bandgap a-Si top cells, the highest Voc achieved for the single-junction top cell was 1.02 V, and top cells with high FF (up to 74%) were fabricated routinely; fabricated high-quality narrow-bandgap a-SiGe solar cells with 8.3% efficiency; found that bandgap-graded buffer layers improve the performance (Voc and FF) of the narrow-bandgap a-SiGe bottom cells; and found that a small amount of oxygen partial pressure ({approximately}2 {times} 10

  5. Simulating the amorphization of [alpha]-quartz under pressure

    SciTech Connect (OSTI)

    Binggeli, N. , PHB-Ecublens, 1015 Lausanne ); Chelikowsky, J.R. ); Wentzcovitch, R.M. )

    1994-04-01

    Extensive molecular-dynamics simulations have been performed within a classical force-field model for the pressure-induced amorphization of quartz. In agreement with earlier molecular-dynamics studies, we find that a phase transition occurs within the experimental pressure range of the amorphization transformation. However, at variance with previous interpretations, we find that the resulting phase is not amorphous. The correlation functions of the equilibrated structure can be shown to be consistent with those of a crystalline phase. Two transformations to ordered structures occur sequentially during the simulations. The first transformation is likely to be related to the recently discovered transition of quartz to an intermediate crystalline phase before its amorphization. The second transformation, instead, yields a compact octahedrally coordinated Si sublattice. The latter structure may be an artifact of the classical force field.

  6. Tensile properties of amorphous diamond films

    SciTech Connect (OSTI)

    Lavan, D.A.; Hohlfelder, R.J.; Sullivan, J.P.; Friedmann, T.A.; Mitchell, M.A.; Ashby, C.I.

    1999-12-02

    The strength and modulus of amorphous diamond, a new material for surface micromachined MEMS and sensors, was tested in uniaxial tension by pulling laterally with a flat tipped diamond in a nanoindenter. Several sample designs were attempted. Of those, only the single layer specimen with a 1 by 2 {micro}m gage cross section and a fixed end rigidly attached to the substrate was successful. Tensile load was calculated by resolving the measured lateral and normal forces into the applied tensile force and frictional losses. Displacement was corrected for machine compliance using the differential stiffness method. Post-mortem examination of the samples was performed to document the failure mode. The load-displacement data from those samples that failed in the gage section was converted to stress-strain curves using carefully measured gage cross section dimensions. Mean fracture strength was found to be 8.5 {+-} 1.4 GPa and the modulus was 831 {+-} 94 GPa. Tensile results are compared to hardness and modulus measurements made using a nanoindenter.

  7. Disordered amorphous calcium carbonate from direct precipitation

    SciTech Connect (OSTI)

    Farhadi Khouzani, Masoud; Chevrier, Daniel M.; Güttlein, Patricia; Hauser, Karin; Zhang, Peng; Hedin, Niklas; Gebauer, Denis

    2015-06-01

    Amorphous calcium carbonate (ACC) is known to play a prominent role in biomineralization. Different studies on the structure of biogenic ACCs have illustrated that they can have distinct short-range orders. However, the origin of so-called proto-structures in synthetic and additive-free ACCs is not well understood. In the current work, ACC has been synthesised in iso-propanolic media by direct precipitation from ionic precursors, and analysed utilising a range of different techniques. The data suggest that this additive-free type of ACC does not resemble clear proto-structural motifs relating to any crystalline polymorph. This can be explained by the undefined pH value in iso-propanolic media, and the virtually instantaneous precipitation. Altogether, this work suggests that aqueous systems and pathways involving pre-nucleation clusters are required for the generation of clear proto-structural features in ACC. Experiments on the ACC-to-crystalline transformation in solution with and without ethanol highlight that polymorph selection is under kinetic control, while the presence of ethanol can control dissolution re-crystallisation pathways.

  8. Disordered amorphous calcium carbonate from direct precipitation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Farhadi Khouzani, Masoud; Chevrier, Daniel M.; Güttlein, Patricia; Hauser, Karin; Zhang, Peng; Hedin, Niklas; Gebauer, Denis

    2015-06-01

    Amorphous calcium carbonate (ACC) is known to play a prominent role in biomineralization. Different studies on the structure of biogenic ACCs have illustrated that they can have distinct short-range orders. However, the origin of so-called proto-structures in synthetic and additive-free ACCs is not well understood. In the current work, ACC has been synthesised in iso-propanolic media by direct precipitation from ionic precursors, and analysed utilising a range of different techniques. The data suggest that this additive-free type of ACC does not resemble clear proto-structural motifs relating to any crystalline polymorph. This can be explained by the undefined pH value inmore » iso-propanolic media, and the virtually instantaneous precipitation. Altogether, this work suggests that aqueous systems and pathways involving pre-nucleation clusters are required for the generation of clear proto-structural features in ACC. Experiments on the ACC-to-crystalline transformation in solution with and without ethanol highlight that polymorph selection is under kinetic control, while the presence of ethanol can control dissolution re-crystallisation pathways.« less

  9. Embrittlement of Metal by Solute Segregation-Induced Amorphization |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Argonne Leadership Computing Facility Embrittlement of Metal by Solute Segregation-Induced Amorphization Authors: Chen, H-P., Kalia, R.K., Kaxiras, E., Lu, G., Nakano, A., Nomura, K-I., van Duin, A.C.T., Vashishta, P., Yuan, Z. Impurities segregated to grain boundaries of a material essentially alter its fracture behavior. A prime example is sulfur segregation-induced embrittlement of nickel, where an observed relation between sulfur-induced amorphization of grain boundaries and

  10. Use of silicon in liquid sintered silicon nitrides and sialons

    DOE Patents [OSTI]

    Raj, R.; Baik, S.

    1984-12-11

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic. 4 figs.

  11. Use of silicon in liquid sintered silicon nitrides and sialons

    DOE Patents [OSTI]

    Raj, Rishi; Baik, Sunggi

    1984-12-11

    This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic.

  12. Process For Direct Integration Of A Thin-Film Silicon P-N Junction Diode With A Magnetic Tunnel Junction

    DOE Patents [OSTI]

    Toet, Daniel; Sigmon, Thomas W.

    2005-08-23

    A process for direct integration of a thin-film silicon p-n junction diode with a magnetic tunnel junction for use in advanced magnetic random access memory (MRAM) cells for high performance, non-volatile memory arrays. The process is based on pulsed laser processing for the fabrication of vertical polycrystalline silicon electronic device structures, in particular p-n junction diodes, on films of metals deposited onto low temperature-substrates such as ceramics, dielectrics, glass, or polymers. The process preserves underlayers and structures onto which the devices are typically deposited, such as silicon integrated circuits. The process involves the low temperature deposition of at least one layer of silicon, either in an amorphous or a polycrystalline phase on a metal layer. Dopants may be introduced in the silicon film during or after deposition. The film is then irradiated with short pulse laser energy that is efficiently absorbed in the silicon, which results in the crystallization of the film and simultaneously in the activation of the dopants via ultrafast melting and solidification. The silicon film can be patterned either before or after crystallization.

  13. Process for direct integration of a thin-film silicon p-n junction diode with a magnetic tunnel junction

    DOE Patents [OSTI]

    Toet, Daniel; Sigmon, Thomas W.

    2003-01-01

    A process for direct integration of a thin-film silicon p-n junction diode with a magnetic tunnel junction for use in advanced magnetic random access memory (MRAM) cells for high performance, non-volatile memory arrays. The process is based on pulsed laser processing for the fabrication of vertical polycrystalline silicon electronic device structures, in particular p-n junction diodes, on films of metals deposited onto low temperature-substrates such as ceramics, dielectrics, glass, or polymers. The process preserves underlayers and structures onto which the devices are typically deposited, such as silicon integrated circuits. The process involves the low temperature deposition of at least one layer of silicon, either in an amorphous or a polycrystalline phase on a metal layer. Dopants may be introduced in the silicon film during or after deposition. The film is then irradiated with short pulse laser energy that is efficiently absorbed in the silicon, which results in the crystallization of the film and simultaneously in the activation of the dopants via ultrafast melting and solidification. The silicon film can be patterned either before or after crystallization.

  14. Process for direct integration of a thin-film silicon p-n junction diode with a magnetic tunnel junction

    DOE Patents [OSTI]

    Toet, Daniel; Sigmon, Thomas W.

    2004-12-07

    A process for direct integration of a thin-film silicon p-n junction diode with a magnetic tunnel junction for use in advanced magnetic random access memory (MRAM) cells for high performance, non-volatile memory arrays. The process is based on pulsed laser processing for the fabrication of vertical polycrystalline silicon electronic device structures, in particular p-n junction diodes, on films of metals deposited onto low temperature-substrates such as ceramics, dielectrics, glass, or polymers. The process preserves underlayers and structures onto which the devices are typically deposited, such as silicon integrated circuits. The process involves the low temperature deposition of at least one layer of silicon, either in an amorphous or a polycrystalline phase on a metal layer. Dopants may be introduced in the silicon film during or after deposition. The film is then irradiated with short pulse laser energy that is efficiently absorbed in the silicon, which results in the crystallization of the film and simultaneously in the activation of the dopants via ultrafast melting and solidification. The silicon film can be patterned either before or after crystallization.

  15. Multicolored Vertical Silicon Nanowires

    SciTech Connect (OSTI)

    Seo, Kwanyong; Wober, Munib; Steinvurzel, P.; Schonbrun, E.; Dan, Yaping; Ellenbogen, T.; Crozier, K. B.

    2011-04-13

    We demonstrate that vertical silicon nanowires take on a surprising variety of colors covering the entire visible spectrum, in marked contrast to the gray color of bulk silicon. This effect is readily observable by bright-field microscopy, or even to the naked eye. The reflection spectra of the nanowires each show a dip whose position depends on the nanowire radii. We compare the experimental data to the results of finite difference time domain simulations to elucidate the physical mechanisms behind the phenomena we observe. The nanowires are fabricated as arrays, but the vivid colors arise not from scattering or diffractive effects of the array, but from the guided mode properties of the individual nanowires. Each nanowire can thus define its own color, allowing for complex spatial patterning. We anticipate that the color filter effect we demonstrate could be employed in nanoscale image sensor devices.

  16. Making silicon stronger.

    SciTech Connect (OSTI)

    Boyce, Brad Lee

    2010-11-01

    Silicon microfabrication has seen many decades of development, yet the structural reliability of microelectromechanical systems (MEMS) is far from optimized. The fracture strength of Si MEMS is limited by a combination of poor toughness and nanoscale etch-induced defects. A MEMS-based microtensile technique has been used to characterize the fracture strength distributions of both standard and custom microfabrication processes. Recent improvements permit 1000's of test replicates, revealing subtle but important deviations from the commonly assumed 2-parameter Weibull statistical model. Subsequent failure analysis through a combination of microscopy and numerical simulation reveals salient aspects of nanoscale flaw control. Grain boundaries, for example, suffer from preferential attack during etch-release thereby forming failure-critical grain-boundary grooves. We will discuss ongoing efforts to quantify the various factors that affect the strength of polycrystalline silicon, and how weakest-link theory can be used to make worst-case estimates for design.

  17. Modified silicon carbide whiskers

    DOE Patents [OSTI]

    Tiegs, Terry N.; Lindemer, Terrence B.

    1991-01-01

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  18. Modified silicon carbide whiskers

    DOE Patents [OSTI]

    Tiegs, T.N.; Lindemer, T.B.

    1991-05-21

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  19. A-Si:H solar cells deposited by the hot wire method

    SciTech Connect (OSTI)

    Iwaniczko, E.; Nelson, B.P.; Molenbroek, E.C.; Schropp, R.; Crandall, R.S.; Mahan, A.H. )

    1994-06-30

    We demonstrate the deposition of a hybrid a-Si:H solar cell in a new research reactor, where we deposit the doped layers by glow discharge and the intrinsic layer by hot wire. After only 10 depositions, we obtained solar cell conversion efficiencies of 7%. We are currently pursuing research avenues which we expect will lead to higher efficiencies.

  20. The effects of hydrogen dilution on Voc in a-Si:H pin solar cells

    SciTech Connect (OSTI)

    Wang, Q.; Crandall, R.S.; Han, D.

    1997-07-01

    The authors study the effects of hydrogen dilution on the open circuit voltage of a-Si:H pin solar cells fabricated by rf glow discharge growth. They keep the p and n layers the same and only vary the i-layer properties. A normal a-Si:H i-layer, an H-diluted i-layer, and a thin H-diluted layer inserted between p and normal i layer are selected for this study. They measure the JV characteristics and the internal electric field distribution using a transient-null-current technique both in annealed and light soaked states. They find that hydrogen dilution does stabilize the Voc either in a bulk H-diluted i layer or in a thin layer between p and normal i layer after 100 hours Am1 sun light soaking. From dark IV measurement, both H-diluted cells show little change in current at voltage near Voc before and after light soaking; while the normal a-Si:H cell does show a noticeable change. Also the internal field measurements find a stronger electric field starting from p and i interface for both H-diluted cells compared to the normal a-Si:H cell. Furthermore, there are no measurable changes in the field profiles after 100 hour AM1 light-soaking for both H-diluted and normal a-Si cells. All these suggest that hydrogen dilution increases the field strength near p and i interface, which is the key that leads to a more stable Voc of H-diluted cells.

  1. Single crystalline mesoporous silicon nanowires

    SciTech Connect (OSTI)

    Hochbaum, Allon; Dargas, Daniel; Hwang, Yun Jeong; Yang, Peidong

    2009-08-18

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. The photoluminescence of these nanowires suggest they are composed of crystalline silicon with small enough dimensions such that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices. A better understanding of this electroless route to mesoporous silicon could lead to facile and general syntheses of different narrow bandgap semiconductor nanostructures for various applications.

  2. Lithium-drifted silicon detector with segmented contacts

    DOE Patents [OSTI]

    Tindall, Craig S.; Luke, Paul N.

    2006-06-13

    A method and apparatus for creating both segmented and unsegmented radiation detectors which can operate at room temperature. The devices include a metal contact layer, and an n-type blocking contact formed from a thin layer of amorphous semiconductor. In one embodiment the material beneath the n-type contact is n-type material, such as lithium compensated silicon that forms the active region of the device. The active layer has been compensated to a degree at which the device may be fully depleted at low bias voltages. A p-type blocking contact layer, or a p-type donor material can be formed beneath a second metal contact layer to complete the device structure. When the contacts to the device are segmented, the device is capable of position sensitive detection and spectroscopy of ionizing radiation, such as photons, electrons, and ions.

  3. Sequential lateral solidification of silicon thin films on low-k dielectrics for low temperature integration

    SciTech Connect (OSTI)

    Carta, Fabio Hlaing, Htay; Kymissis, Ioannis; Gates, Stephen M.; Edelstein, Daniel C.; Limanov, Alexander B.; Im, James S.

    2014-12-15

    We present the excimer laser crystallization of amorphous silicon on a low dielectric constant (low-k) insulator for very large scale integration monolithic 3D integration and demonstrate that low dielectric constant materials are suitable substrates for 3D integration through laser crystallization of silicon thin films. We crystallized 100 nm amorphous silicon on top of SiO{sub 2} and SiCOH (low-k) dielectrics, at different material thicknesses (1 μm, 0.75 μm, and 0.5 μm). The amorphous silicon crystallization on low-k dielectric requires 35% less laser energy than on an SiO{sub 2} dielectric. This difference is related to the thermal conductivity of the two materials, in agreement with one dimensional simulations of the crystallization process. We analyzed the morphology of the material through defect-enhanced microscopy, Raman spectroscopy, and X-ray diffraction analysis. SEM micrographs show that polycrystalline silicon is characterized by micron-long grains with an average width of 543 nm for the SiO{sub 2} sample and 570 nm for the low-k samples. Comparison of the Raman spectra does not show any major difference in film quality for the two different dielectrics, and polycrystalline silicon peaks are closely placed around 517 cm{sup −1}. From X-ray diffraction analysis, the material crystallized on SiO{sub 2} shows a preferential (111) crystal orientation. In the SiCOH case, the 111 peak strength decreases dramatically and samples do not show preferential crystal orientation. A 1D finite element method simulation of the crystallization process on a back end of line structure shows that copper (Cu) damascene interconnects reach a temperature of 70 °C or lower with a 0.5 μm dielectric layer between the Cu and the molten Si layer, a favorable condition for monolithic 3D integration.

  4. Silicon Crystals Inc | Open Energy Information

    Open Energy Info (EERE)

    Zip: 95742 Product: Supplier of semi-conductor grade silicon for applications that demand unusual shapes and sizes. References: Silicon Crystals Inc1 This article is a stub....

  5. Silicon on insulator with active buried regions

    DOE Patents [OSTI]

    McCarthy, Anthony M.

    1996-01-01

    A method for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors.

  6. Silicon on insulator with active buried regions

    DOE Patents [OSTI]

    McCarthy, A.M.

    1998-06-02

    A method is disclosed for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors. 10 figs.

  7. Silicon on insulator with active buried regions

    DOE Patents [OSTI]

    McCarthy, A.M.

    1996-01-30

    A method is disclosed for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors. 10 figs.

  8. Silicon on insulator with active buried regions

    DOE Patents [OSTI]

    McCarthy, Anthony M.

    1998-06-02

    A method for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors.

  9. Silicon Chemical Corp SCC | Open Energy Information

    Open Energy Info (EERE)

    Corp SCC Jump to: navigation, search Name: Silicon Chemical Corp (SCC) Place: Vancouver, Washington State Zip: 98687 Product: US manufacturer of polysilicon and silicon chemical...

  10. Laser, Supercomputer Measure Speedy Electrons in Silicon

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laser, Supercomputer Measure Speedy Electrons in Silicon Laser, Supercomputer Measure Speedy Electrons in Silicon Simulations at NERSC Help Illuminate Attosecond Laser Experiment ...

  11. Silicon Border Development LLC | Open Energy Information

    Open Energy Info (EERE)

    Silicon Border Development LLC Jump to: navigation, search Name: Silicon Border Development LLC Place: Poway, California Zip: 92064 Sector: Solar Product: US-based developer of...

  12. Crystalline Silicon Photovolatic Cell Basics | Department of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Crystalline Silicon Photovolatic Cell Basics Crystalline Silicon Photovolatic Cell Basics ... This lattice comprises the solid material that forms the photovoltaic (PV) cell's ...

  13. Longwei Silicon Co Ltd | Open Energy Information

    Open Energy Info (EERE)

    Silicon Co Ltd Place: Liancheng, Fujian Province, China Sector: Solar Product: A Chinese sillicon metal producer who also produce 4N-6N silicon for solar use. Coordinates:...

  14. Silicon Carbide JFET Switch

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    5kV Enhancement-Model Silicon Carbide JFET Switch The novel 6.5kV SiC device and power module represent the world's highest-voltage module based on reliable, normally-off SiC JFETs. It reduces switching losses over that of Si-IGBTs by a factor of 20 and exhibits the fastest turn- on and turn-off of any 6.5kV-rated power module. Another major aspect of what makes this product unique is USCi's development and manufacturing approach. JFETs are simple transistor switches, yet for SiC materials, a

  15. Silicon oxynitride films deposited by reactive high power impulse magnetron sputtering using nitrous oxide as a single-source precursor

    SciTech Connect (OSTI)

    Hänninen, Tuomas Schmidt, Susann; Jensen, Jens; Hultman, Lars; Högberg, Hans

    2015-09-15

    Silicon oxynitride thin films were synthesized by reactive high power impulse magnetron sputtering of silicon in argon/nitrous oxide plasmas. Nitrous oxide was employed as a single-source precursor supplying oxygen and nitrogen for the film growth. The films were characterized by elastic recoil detection analysis, x-ray photoelectron spectroscopy, x-ray diffraction, x-ray reflectivity, scanning electron microscopy, and spectroscopic ellipsometry. Results show that the films are silicon rich, amorphous, and exhibit a random chemical bonding structure. The optical properties with the refractive index and the extinction coefficient correlate with the film elemental composition, showing decreasing values with increasing film oxygen and nitrogen content. The total percentage of oxygen and nitrogen in the films is controlled by adjusting the gas flow ratio in the deposition processes. Furthermore, it is shown that the film oxygen-to-nitrogen ratio can be tailored by the high power impulse magnetron sputtering-specific parameters pulse frequency and energy per pulse.

  16. Molecular dynamics simulations of grain boundaries in thin nanocrystalline silicon films

    SciTech Connect (OSTI)

    Berman, G.P.; Doolen, G.D.; Mainieri, R.; Campbell, D.K.; Luchnikov, V.A. |

    1997-10-01

    Using molecular dynamics simulations, the grain boundaries in thin polycrystalline silicon films (considered as promising material for future nanoelectronic devices) are investigated. It is shown that in polysilicon film with randomly oriented grains the majority of grain boundaries are disordered. However, some grains with small mutual orientation differences can form extended crystalline patterns. The structure of the grain boundaries satisfies the thermodynamical criterion. The majority of atoms in the grain boundaries are tetrahedrally coordinated with the nearest neighbors, even though the grain boundaries are disordered. The grain boundary matter is characterized as an amorphous phase with a characteristic tetragonality value.

  17. Cordierite silicon nitride filters

    SciTech Connect (OSTI)

    Sawyer, J.; Buchan, B. ); Duiven, R.; Berger, M. ); Cleveland, J.; Ferri, J. )

    1992-02-01

    The objective of this project was to develop a silicon nitride based crossflow filter. This report summarizes the findings and results of the project. The project was phased with Phase I consisting of filter material development and crossflow filter design. Phase II involved filter manufacturing, filter testing under simulated conditions and reporting the results. In Phase I, Cordierite Silicon Nitride (CSN) was developed and tested for permeability and strength. Target values for each of these parameters were established early in the program. The values were met by the material development effort in Phase I. The crossflow filter design effort proceeded by developing a macroscopic design based on required surface area and estimated stresses. Then the thermal and pressure stresses were estimated using finite element analysis. In Phase II of this program, the filter manufacturing technique was developed, and the manufactured filters were tested. The technique developed involved press-bonding extruded tiles to form a filter, producing a monolithic filter after sintering. Filters manufactured using this technique were tested at Acurex and at the Westinghouse Science and Technology Center. The filters did not delaminate during testing and operated and high collection efficiency and good cleanability. Further development in areas of sintering and filter design is recommended.

  18. Lasing modes in polycrystalline and amorphous photonic structures

    SciTech Connect (OSTI)

    Yang, Jin-Kyu; Noh, Heeso; Liew, Seng Fatt; Rooks, Michael J.; Solomon, Glenn S.; Cao Hui

    2011-09-15

    We systematically studied the lasing characteristics in photonic polycrystalline and amorphous structures. 2D arrays of air holes were fabricated in a GaAs membrane. InAs quantum dots embedded in the membrane provide gain for lasing under optical pumping. The lasing modes are spatially localized, and blue shift as the structural order becomes short ranged. Our three-dimensional numerical simulations reveal that the out-of-plane leakage of the lasing mode dominates over the in-plane leakage. The lasing modes in a photonic polycrystalline move away from the center frequency of the photonic band gap to reduce the out-of-plane leakage. In a photonic amorphous structure, the short-range order improves optical confinement and enhances the quality factor of resonances. Understanding the behavior of photonic polycrystalline laser and amorphous laser opens the possibility of controlling lasing characteristic by varying the degree of structural order.

  19. Amorphous copper tungsten oxide with tunable band gaps

    SciTech Connect (OSTI)

    Chen Le; Shet, Sudhakar; Tang Houwen; Wang Heli; Yan Yanfa; Turner, John; Al-Jassim, Mowafak; Ahn, Kwang-soon

    2010-08-15

    We report on the synthesis of amorphous copper tungsten oxide thin films with tunable band gaps. The thin films are synthesized by the magnetron cosputtering method. We find that due to the amorphous nature, the Cu-to-W ratio in the films can be varied without the limit of the solubility (or phase separation) under appropriate conditions. As a result, the band gap and conductivity type of the films can be tuned by controlling the film composition. Unfortunately, the amorphous copper tungsten oxides are not stable in aqueous solution and are not suitable for the application of photoelectrochemical splitting of water. Nonetheless, it provides an alternative approach to search for transition metal oxides with tunable band gaps.

  20. Relationship between nanocrystalline and amorphous microstructures by molecular dynamics simulation

    SciTech Connect (OSTI)

    Keblinski, P.; Phillpot, S.R.; Wolf, D.; Gleiter, H.

    1996-08-01

    A recent molecular dynamics simulation method for growth of fully dense nanocrystalline materials crystallized from melt was used with the Stillinger-Weber three-body potential to synthesize nanocrystalline Si with a grain size up to 75{Angstrom}. Structures of the highly constrained grain boundaries (GBs), triple lines, and point grain junctions were found to be highly disordered and similar to the structure of amorphous Si. These and earlier results for fcc metals suggest that a nanocrystalline microstructure may be viewed as a two-phase system, namely an ordered crystalline phase in the grain interiors connected by an amorphous, intergranular, glue-like phase. Analysis of the structures of bicrystalline GBs in the same materials reveals the presence of an amorphous intergranular equilibrium phase only in the high-energy but not the low-energy GBs, suggesting that only high-energy boundaries are present in nanocrystalline microstructures.

  1. The Effect of Fluoroethylene Carbonate as an Additive on the Solid Electrolyte Interphase on Silicon Lithium-Ion Electrodes

    SciTech Connect (OSTI)

    Schroder, Kjell; Li, Juchuan; Dudney, Nancy J.; Meng, Ying Shirley; Stevenson, Keith J.; Alvarado, Judith

    2015-08-03

    Fluoroethylene carbonate (FEC) has become a standard electrolyte additive for use with silicon negative electrodes, but how FEC affects solid electrolyte interphase (SEI) formation on the silicon anode’s surface is still not well understood. Herein, SEI formed from LiPF6-based carbonate electrolytes, with and without FEC, were investigated on 50 nm thick amorphous silicon thin film electrodes to understand the role of FEC on silicon electrode surface reactions. In contrast to previous work, anhydrous and anoxic techniques were used to prevent air and moisture contamination of prepared SEI films. This allowed for accurate characterization of the SEI structure and composition by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry depth profiling. These results show that FEC reduction leads to fluoride ion and LiF formation, consistent with previous computational and experimental results. Surprisingly, we also find that these species decrease lithium-ion solubility and increase the reactivity of the silicon surface. We conclude that the effectiveness of FEC at improving the Coulombic efficiency and capacity retention is due to fluoride ion formation from reduction of the electrolyte, which leads to the chemical attack of any silicon-oxide surface passivation layers and the formation of a kinetically stable SEI comprising predominately lithium fluoride and lithium oxide.

  2. The Effect of Fluoroethylene Carbonate as an Additive on the Solid Electrolyte Interphase on Silicon Lithium-Ion Electrodes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Schroder, Kjell; Li, Juchuan; Dudney, Nancy J.; Meng, Ying Shirley; Stevenson, Keith J.; Alvarado, Judith

    2015-08-03

    Fluoroethylene carbonate (FEC) has become a standard electrolyte additive for use with silicon negative electrodes, but how FEC affects solid electrolyte interphase (SEI) formation on the silicon anode’s surface is still not well understood. Herein, SEI formed from LiPF6-based carbonate electrolytes, with and without FEC, were investigated on 50 nm thick amorphous silicon thin film electrodes to understand the role of FEC on silicon electrode surface reactions. In contrast to previous work, anhydrous and anoxic techniques were used to prevent air and moisture contamination of prepared SEI films. This allowed for accurate characterization of the SEI structure and composition bymore » X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry depth profiling. These results show that FEC reduction leads to fluoride ion and LiF formation, consistent with previous computational and experimental results. Surprisingly, we also find that these species decrease lithium-ion solubility and increase the reactivity of the silicon surface. We conclude that the effectiveness of FEC at improving the Coulombic efficiency and capacity retention is due to fluoride ion formation from reduction of the electrolyte, which leads to the chemical attack of any silicon-oxide surface passivation layers and the formation of a kinetically stable SEI comprising predominately lithium fluoride and lithium oxide.« less

  3. Amorphous Alloy Membranes for High Temperature Hydrogen Separation

    SciTech Connect (OSTI)

    Coulter, K

    2013-09-30

    At the beginning of this project, thin film amorphous alloy membranes were considered a nascent but promising new technology for industrial-scale hydrogen gas separations from coal- derived syngas. This project used a combination of theoretical modeling, advanced physical vapor deposition fabricating, and laboratory and gasifier testing to develop amorphous alloy membranes that had the potential to meet Department of Energy (DOE) targets in the testing strategies outlined in the NETL Membrane Test Protocol. The project is complete with Southwest Research Institute® (SwRI®), Georgia Institute of Technology (GT), and Western Research Institute (WRI) having all operated independently and concurrently. GT studied the hydrogen transport properties of several amorphous alloys and found that ZrCu and ZrCuTi were the most promising candidates. GT also evaluated the hydrogen transport properties of V, Nb and Ta membranes coated with different transition-metal carbides (TMCs) (TM = Ti, Hf, Zr) catalytic layers by employing first-principles calculations together with statistical mechanics methods and determined that TiC was the most promising material to provide catalytic hydrogen dissociation. SwRI developed magnetron coating techniques to deposit a range of amorphous alloys onto both porous discs and tubular substrates. Unfortunately none of the amorphous alloys could be deposited without pinhole defects that undermined the selectivity of the membranes. WRI tested the thermal properties of the ZrCu and ZrNi alloys and found that under reducing environments the upper temperature limit of operation without recrystallization is ~250 °C. There were four publications generated from this project with two additional manuscripts in progress and six presentations were made at national and international technical conferences. The combination of the pinhole defects and the lack of high temperature stability make the theoretically identified most promising candidate amorphous alloys

  4. Containerless synthesis of amorphous and nanophase organic materials

    DOE Patents [OSTI]

    Benmore, Chris J.; Weber, Johann R.

    2016-05-03

    The invention provides a method for producing a mixture of amorphous compounds, the method comprising supplying a solution containing the compounds; and allowing at least a portion of the solvent of the solution to evaporate while preventing the solute of the solution from contacting a nucleation point. Also provided is a method for transforming solids to amorphous material, the method comprising heating the solids in an environment to form a melt, wherein the environment contains no nucleation points; and cooling the melt in the environment.

  5. Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

    DOE Patents [OSTI]

    Corman, Gregory Scot; Luthra, Krishan Lal

    2002-01-01

    A fiber-reinforced silicon-silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon-silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

  6. Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

    DOE Patents [OSTI]

    Corman, Gregory Scot; Luthra, Krishan Lal

    1999-01-01

    A fiber-reinforced silicon--silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon--silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

  7. Silicon nitride/silicon carbide composite densified materials prepared using composite powders

    DOE Patents [OSTI]

    Dunmead, S.D.; Weimer, A.W.; Carroll, D.F.; Eisman, G.A.; Cochran, G.A.; Susnitzky, D.W.; Beaman, D.R.; Nilsen, K.J.

    1997-07-01

    Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

  8. A silicon photomultiplier readout for time of flight neutron spectroscopy with {gamma}-ray detectors

    SciTech Connect (OSTI)

    Pietropaolo, A.; Gorini, G.; Festa, G.; Andreani, C.; De Pascale, M. P.; Reali, E.; Grazzi, F.; Schooneveld, E. M.

    2009-09-15

    The silicon photomultiplier (SiPM) is a recently developed photosensor used in particle physics, e.g., for detection of minimum ionizing particles and/or Cherenkov radiation. Its performance is comparable to that of photomultiplier tubes, but with advantages in terms of reduced volume and magnetic field insensitivity. In the present study, the performance of a gamma ray detector made of an yttrium aluminum perovskite scintillation crystal and a SiPM-based readout is assessed for use in time of flight neutron spectroscopy. Measurements performed at the ISIS pulsed neutron source demonstrate the feasibility of {gamma}-detection based on the new device.

  9. Silicon nitride ceramic comprising samaria and ytterbia

    DOE Patents [OSTI]

    Yeckley, Russell L.

    1996-01-01

    This invention relates to a sintered silicon nitride ceramic comprising samaria and ytterbia for enhanced toughness.

  10. High specific activity silicon-32

    DOE Patents [OSTI]

    Phillips, D.R.; Brzezinski, M.A.

    1996-06-11

    A process for preparation of silicon-32 is provided and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidation state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  11. High specific activity silicon-32

    DOE Patents [OSTI]

    Phillips, Dennis R.; Brzezinski, Mark A.

    1996-01-01

    A process for preparation of silicon-32 is provided and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution to from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidization state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.

  12. Low temperature production of large-grain polycrystalline semiconductors

    DOE Patents [OSTI]

    Naseem, Hameed A.; Albarghouti, Marwan

    2007-04-10

    An oxide or nitride layer is provided on an amorphous semiconductor layer prior to performing metal-induced crystallization of the semiconductor layer. The oxide or nitride layer facilitates conversion of the amorphous material into large grain polycrystalline material. Hence, a native silicon dioxide layer provided on hydrogenated amorphous silicon (a-Si:H), followed by deposited Al permits induced crystallization at temperatures far below the solid phase crystallization temperature of a-Si. Solar cells and thin film transistors can be prepared using this method.

  13. Anomalous small-angle X-ray scattering of nanoporous two-phase atomistic models for amorphous silicon–germanium alloys

    SciTech Connect (OSTI)

    Chehaidar, A.

    2015-09-15

    The present work deals with a detailed analysis of the anomalous small-angle X-ray scattering in amorphous silicon–germanium alloy using the simulation technique. We envisage the nanoporous two-phase alloy model consisting in a mixture of Ge-rich and Ge-poor domains and voids at the nanoscale. By substituting Ge atoms for Si atoms in nanoporous amorphous silicon network, compositionally heterogeneous alloys are generated with various composition-contrasts between the two phases. After relaxing the as-generated structure, we compute its radial distribution function, and then we deduce by the Fourier transform technique its anomalous X-ray scattering pattern. Using a smoothing procedure, the computed X-ray scattering patterns are corrected for the termination errors due to the finite size of the model, allowing so a rigorous quantitative analysis of the anomalous small-angle scattering. Our simulation shows that, as expected, the anomalous small-angle X-ray scattering technique is a tool of choice for characterizing compositional heterogeneities coexisting with structural inhomogeneities in an amorphous alloy. Furthermore, the sizes of the compositional nanoheterogeneities, as measured by anomalous small-angle X-ray scattering technique, are X-ray energy independent. A quantitative analysis of the separated reduced anomalous small-angle X-ray scattering, as defined in this work, provided a good estimate of their size.

  14. Process for forming retrograde profiles in silicon

    DOE Patents [OSTI]

    Weiner, K.H.; Sigmon, T.W.

    1996-10-15

    A process is disclosed for forming retrograde and oscillatory profiles in crystalline and polycrystalline silicon. The process consisting of introducing an n- or p-type dopant into the silicon, or using prior doped silicon, then exposing the silicon to multiple pulses of a high-intensity laser or other appropriate energy source that melts the silicon for short time duration. Depending on the number of laser pulses directed at the silicon, retrograde profiles with peak/surface dopant concentrations which vary are produced. The laser treatment can be performed in air or in vacuum, with the silicon at room temperature or heated to a selected temperature.

  15. Process for forming retrograde profiles in silicon

    DOE Patents [OSTI]

    Weiner, Kurt H.; Sigmon, Thomas W.

    1996-01-01

    A process for forming retrograde and oscillatory profiles in crystalline and polycrystalline silicon. The process consisting of introducing an n- or p-type dopant into the silicon, or using prior doped silicon, then exposing the silicon to multiple pulses of a high-intensity laser or other appropriate energy source that melts the silicon for short time duration. Depending on the number of laser pulses directed at the silicon, retrograde profiles with peak/surface dopant concentrations which vary from 1-1e4 are produced. The laser treatment can be performed in air or in vacuum, with the silicon at room temperature or heated to a selected temperature.

  16. Synthesis and Analysis of Alpha Silicon Carbide Components for Encapsulation of Fuel Rods and Pellets

    SciTech Connect (OSTI)

    Kevin M. McHugh; John E. Garnier; George W. Griffith

    2011-09-01

    The chemical, mechanical and thermal properties of silicon carbide (SiC) along with its low neutron activation and stability in a radiation field make it an attractive material for encapsulating fuel rods and fuel pellets. The alpha phase (6H) is particularly stable. Unfortunately, it requires very high temperature processing and is not readily available in fibers or near-net shapes. This paper describes an investigation to fabricate a-SiC as thin films, fibers and near-net-shape products by direct conversion of carbon using silicon monoxide vapor at temperatures less than 1700 C. In addition, experiments to nucleate the alpha phase during pyrolysis of polysilazane, are also described. Structure and composition were characterized using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Preliminary tensile property analysis of fibers was also performed.

  17. Development of high, stable-efficiency triple-junction a-Si alloy solar cells. Final technical report

    SciTech Connect (OSTI)

    Deng, X.; Jones, S.J.; Liu, T.; Izu, M.

    1998-04-01

    This report summarizes Energy Conversion Devices, Inc.`s (ECD) research under this program. ECD researchers explored the deposition of a-Si at high rates using very-high-frequency plasma MHz, and compared these VHF i-layers with radio-frequency (RF) plasma-deposited i-layers. ECD conducted comprehensive research to develop a {mu}c-Si p{sup +} layer using VHF deposition process with the objectives of establishing a wider process window for the deposition of high-quality p{sup +} materials and further enhancing their performance of a-Si solar cells by improving its p-layers. ECD optimized the deposition of the intrinsic a-Si layer and the boron-doped {mu}c-Si p{sup +} layer to improve the V{sub oc}. Researchers deposited wide-bandgap a-Si films using high hydrogen dilution; investigated the deposition of the ZnO layer (for use in back-reflector) using a sputter deposition process involving metal Zn targets; and obtained a baseline fabrication for single-junction a-Si n-i-p devices with 10.6% initial efficiency and a baseline fabrication for triple-junction a-Si devices with 11.2% initial efficiency. ECD researchers also optimized the deposition parameters for a-SiGe with high Ge content; designed a novel structure for the p-n tunnel junction (recombination layer) in a multiple-junction solar cell; and demonstrated, in n-i-p solar cells, the improved stability of a-Si:H:F materials when deposited using a new fluorine precursor. Researchers investigated the use of c-Si(n{sup +})/a-Si alloy/Pd Schottky barrier device as a tool for the effective evaluation of photovoltaic performance on a-Si alloy materials. Through alterations in the deposition conditions and system hardware, researchers improved their understanding for the deposition of uniform and high-quality a-Si and a-SiGe films over large areas. ECD researchers also performed extensive research to optimize the deposition process of the newly constructed 5-MW back-reflector deposition machine.

  18. Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys

    SciTech Connect (OSTI)

    Kalay, Yunus Eren

    2008-10-15

    Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current dissertation involves an extensive set of experimental, analytical, and computational studies designed to increase the overall understanding of morphological selection, phase competition, and structural hierarchy that occurs under far-from equilibrium conditions. High pressure gas atomization and Cu-block melt-spinning are the two different rapid solidification techniques applied in this study. The research is mainly focused on Al-Si and Al-Sm alloy systems. Silicon and samarium produce different, yet favorable, systems for exploration when alloyed with aluminum under far-from equilibrium conditions. One of the main differences comes from the positions of their respective T{sub 0} curves, which makes Al-Si a good candidate for solubility extension while the plunging T{sub 0} line in Al-Sm promotes glass formation. The rapidly solidified gas-atomized Al-Si powders within a composition range of 15 to 50 wt% Si are examined using scanning and transmission electron microscopy. The non-equilibrium partitioning and morphological selection observed by examining powders at different size classes are described via a microstructure map. The interface velocities and the amount of undercooling present in the powders are estimated from measured eutectic spacings based on Jackson-Hunt (JH) and Trivedi-Magnin-Kurz (TMK) models, which permit a direct comparison of theoretical predictions. For an average particle size of 10 {micro}m with a Peclet number of {approx}0.2, JH and TMK deviate from each

  19. Density driven structural transformations in amorphous semiconductor clathrates

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Tulk, Christopher A; dos Santos, Antonio M.; Neuefeind, Joerg C; Molaison, Jamie J; Sales, Brian C; Honkimaeki, Veijo

    2015-01-01

    The pressure induced crystalline collapse at 14.7 GPa and polyamorphic structures of the semiconductor clathrate Sr8Ga16Ge30 are reported up to 35 GPa. In-situ total scattering measurements under pressure allow the direct microscopic inspection of the mechanisms associated with pressure induced amorphization in these systems, as well as the structure of the recovered phase. It is observed that, between 14.7 and 35 GPa the second peak in the structure factor function gradually disappears. Analysis of the radial distribution function extracted from those data indicate that this feature is associated with gradual cage collapse and breakdown of the tetrahedral structure with themore » consequent systematic lengthening of the nearest-neighbor framework bonds. This suggests an overall local coordination change to an even higher density amorphous form. Upon recovery from high pressure, the sample remains amorphous, and while there is some indication of the guest-host cage reforming, it doesn't seem that the tetrahedral coordination is recovered. As such, the compresion-decompression process in this systems gives rise to three distict amorphous forms.« less

  20. Method of depositing wide bandgap amorphous semiconductor materials

    DOE Patents [OSTI]

    Ellis, Jr., Frank B.; Delahoy, Alan E.

    1987-09-29

    A method of depositing wide bandgap p type amorphous semiconductor materials on a substrate without photosensitization by the decomposition of one or more higher order gaseous silanes in the presence of a p-type catalytic dopant at a temperature of about 200.degree. C. and a pressure in the range from about 1-50 Torr.

  1. Density driven structural transformations in amorphous semiconductor clathrates

    SciTech Connect (OSTI)

    Tulk, Christopher A; dos Santos, Antonio M.; Neuefeind, Joerg C; Molaison, Jamie J; Sales, Brian C; Honkimaeki, Veijo

    2015-01-01

    The pressure induced crystalline collapse at 14.7 GPa and polyamorphic structures of the semiconductor clathrate Sr8Ga16Ge30 are reported up to 35 GPa. In-situ total scattering measurements under pressure allow the direct microscopic inspection of the mechanisms associated with pressure induced amorphization in these systems, as well as the structure of the recovered phase. It is observed that, between 14.7 and 35 GPa the second peak in the structure factor function gradually disappears. Analysis of the radial distribution function extracted from those data indicate that this feature is associated with gradual cage collapse and breakdown of the tetrahedral structure with the consequent systematic lengthening of the nearest-neighbor framework bonds. This suggests an overall local coordination change to an even higher density amorphous form. Upon recovery from high pressure, the sample remains amorphous, and while there is some indication of the guest-host cage reforming, it doesn't seem that the tetrahedral coordination is recovered. As such, the compresion-decompression process in this systems gives rise to three distict amorphous forms.

  2. A High Temperature Silicon Carbide mosfet Power Module With Integrated Silicon-On-Insulator-Based Gate Drive

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Zhiqiang; Shi, Xiaojie; Tolbert, Leon M.; Wang, Fei Fred; Liang, Zhenxian; Costinett, Daniel; Blalock, Benjamin J.

    2014-04-30

    Here we present a board-level integrated silicon carbide (SiC) MOSFET power module for high temperature and high power density application. Specifically, a silicon-on-insulator (SOI)-based gate driver capable of operating at 200°C ambient temperature is designed and fabricated. The sourcing and sinking current capability of the gate driver are tested under various ambient temperatures. Also, a 1200 V/100 A SiC MOSFET phase-leg power module is developed utilizing high temperature packaging technologies. The static characteristics, switching performance, and short-circuit behavior of the fabricated power module are fully evaluated at different temperatures. Moreover, a buck converter prototype composed of the SOI gate drivermore » and SiC power module is built for high temperature continuous operation. The converter is operated at different switching frequencies up to 100 kHz, with its junction temperature monitored by a thermosensitive electrical parameter and compared with thermal simulation results. The experimental results from the continuous operation demonstrate the high temperature capability of the power module at a junction temperature greater than 225°C.« less

  3. Huachang Silicon Material Co Ltd | Open Energy Information

    Open Energy Info (EERE)

    Huachang Silicon Material Co Ltd Jump to: navigation, search Name: Huachang Silicon Material Co Ltd Place: Jinzhou, Liaoning Province, China Product: A monocrystalline silicon...

  4. Jinzhou Huari Silicon Material Co Ltd | Open Energy Information

    Open Energy Info (EERE)

    Huari Silicon Material Co Ltd Jump to: navigation, search Name: Jinzhou Huari Silicon Material Co Ltd Place: China Product: Chinese manufacturer of mono-crystalline silicon ingot....

  5. A forward bias method for lag correction of an a-Si flat panel detector

    SciTech Connect (OSTI)

    Starman, Jared; Tognina, Carlo; Partain, Larry; Fahrig, Rebecca

    2012-01-15

    Purpose: Digital a-Si flat panel (FP) x-ray detectors can exhibit detector lag, or residual signal, of several percent that can cause ghosting in projection images or severe shading artifacts, known as the radar artifact, in cone-beam computed tomography (CBCT) reconstructions. A major contributor to detector lag is believed to be defect states, or traps, in the a-Si layer of the FP. Software methods to characterize and correct for the detector lag exist, but they may make assumptions such as system linearity and time invariance, which may not be true. The purpose of this work is to investigate a new hardware based method to reduce lag in an a-Si FP and to evaluate its effectiveness at removing shading artifacts in CBCT reconstructions. The feasibility of a novel, partially hardware based solution is also examined. Methods: The proposed hardware solution for lag reduction requires only a minor change to the FP. For pulsed irradiation, the proposed method inserts a new operation step between the readout and data collection stages. During this new stage the photodiode is operated in a forward bias mode, which fills the defect states with charge. A Varian 4030CB panel was modified to allow for operation in the forward bias mode. The contrast of residual lag ghosts was measured for lag frames 2 and 100 after irradiation ceased for standard and forward bias modes. Detector step response, lag, SNR, modulation transfer function (MTF), and detective quantum efficiency (DQE) measurements were made with standard and forward bias firmware. CBCT data of pelvic and head phantoms were also collected. Results: Overall, the 2nd and 100th detector lag frame residual signals were reduced 70%-88% using the new method. SNR, MTF, and DQE measurements show a small decrease in collected signal and a small increase in noise. The forward bias hardware successfully reduced the radar artifact in the CBCT reconstruction of the pelvic and head phantoms by 48%-81%. Conclusions: Overall, the

  6. Direct Production of Silicones From Sand

    SciTech Connect (OSTI)

    Larry N. Lewis; F.J. Schattenmann: J.P. Lemmon

    2001-09-30

    Silicon, in the form of silica and silicates, is the second most abundant element in the earth's crust. However the synthesis of silicones (scheme 1) and almost all organosilicon chemistry is only accessible through elemental silicon. Silicon dioxide (sand or quartz) is converted to chemical-grade elemental silicon in an energy intensive reduction process, a result of the exceptional thermodynamic stability of silica. Then, the silicon is reacted with methyl chloride to give a mixture of methylchlorosilanes catalyzed by cooper containing a variety of tract metals such as tin, zinc etc. The so-called direct process was first discovered at GE in 1940. The methylchlorosilanes are distilled to purify and separate the major reaction components, the most important of which is dimethyldichlorosilane. Polymerization of dimethyldichlorosilane by controlled hydrolysis results in the formation of silicone polymers. Worldwide, the silicones industry produces about 1.3 billion pounds of the basic silicon polymer, polydimethylsiloxane.

  7. Amorphous metal formulations and structured coatings for corrosion and wear resistance

    DOE Patents [OSTI]

    Farmer, Joseph C.

    2014-07-15

    A system for coating a surface comprising providing a source of amorphous metal that contains more than 11 elements and applying the amorphous metal that contains more than 11 elements to the surface by a spray. Also a coating comprising a composite material made of amorphous metal that contains more than 11 elements. An apparatus for producing a corrosion-resistant amorphous-metal coating on a structure comprises a deposition chamber, a deposition source in the deposition chamber that produces a deposition spray, the deposition source containing a composite material made of amorphous metal that contains more than 11 elements, and a system that directs the deposition spray onto the structure.

  8. Amorphous metal formulations and structured coatings for corrosion and wear resistance

    DOE Patents [OSTI]

    Farmer, Joseph C.

    2011-12-13

    A system for coating a surface comprising providing a source of amorphous metal that contains more than 11 elements and applying the amorphous metal that contains more than 11 elements to the surface by a spray. Also a coating comprising a composite material made of amorphous metal that contains more than 11 elements. An apparatus for producing a corrosion-resistant amorphous-metal coating on a structure comprises a deposition chamber, a deposition source in the deposition chamber that produces a deposition spray, the deposition source containing a composite material made of amorphous metal that contains more than 11 elements, and a system that directs the deposition spray onto the structure.

  9. Comparative study of hydrogen diffusion in hot-wire and glow-discharge-deposited a-Si:H

    SciTech Connect (OSTI)

    Shinar, J.; Shinar, R.; Junge, K.E.; Iwaniczko, E.; Mahan, A.H.; Crandall, R.S.; Branz, H.M.

    1999-07-01

    Long-range atomic H motion in hot-wire deposited (HW) a-Si:H is compared directly to that in glow-discharge deposited (GD) a-Si:H by monitoring the deuterium secondary ion mass spectrometry (DSIMS) profiles in [GD a-Si:H]/[GD a-Si:(H,D)]/[HW a-Si:H] multilayers vs annealing temperature and time. While the profiles in the GD layer are in excellent agreement with complenetary error-function behavior and previous studies, the profiles in the HW layer suggest that the multiple-trapping motion of the H and D atoms is much slower, possibly due to an interface layer of defects. However, an exponential tail of D atoms extends deep into the HW layer, probably due to a long diffusion length of mobile D atoms, consistent with the established release times of H and D from the GD layer and H loss typical during growth of HW films. The results are also discussed in terms of the H exchange model and compared to previous NMR studies of HW a-Si:H, which suggest that most of the hydrogen in the HW layer is concentrated in H-rich clusters dispersed in a network of very low H content.

  10. Flexible A-15 superconducting tape via the amorphous state

    SciTech Connect (OSTI)

    Clapp, M.T.; Shi, D.

    1985-05-15

    The melt spinning technique was used to rapidly solidify superconducting materials. In the Ti/sub 3/Nb/sub 6/Mo/sub 3/Si/sub 4/ alloy system, it was possible to form metastable A-15 and amorphous ribbons as the quenching rate was increased. The liquid-quenched A-15 ribbons were extremely brittle, which is typical of this crystal structure. The metastable A-15 phase could also be formed by annealing the amorphous ribbons. These, however, were far more flexible, their percent elongation being up to 30 times greater than that of the liquid quenched A-15's. The flexibility appeared to depend on grain size, and increased as the grain size decreased. This is consistent with behavior observed in other brittle materials of a brittle to ductile transition as a function of grain size.

  11. Amorphous tin-cadmium oxide films and the production thereof

    DOE Patents [OSTI]

    Li, Xiaonan; Gessert, Timothy A

    2013-10-29

    A tin-cadmium oxide film having an amorphous structure and a ratio of tin atoms to cadmium atoms of between 1:1 and 3:1. The tin-cadmium oxide film may have an optical band gap of between 2.7 eV and 3.35 eV. The film may also have a charge carrier concentration of between 1.times.10.sup.20 cm.sup.-3 and 2.times.10.sup.20 cm.sup.-3. The tin cadmium oxide film may also exhibit a Hall mobility of between 40 cm.sup.2V.sup.-1 s.sup.-1 and 60 cm.sup.2V.sup.-1 s.sup.-1. Also disclosed is a method of producing an amorphous tin-cadmium oxide film as described and devices using same.

  12. Formation of amorphous metal alloys by chemical vapor deposition

    DOE Patents [OSTI]

    Mullendore, A.W.

    1988-03-18

    Amorphous alloys are deposited by a process of thermal dissociation of mixtures of organometallic compounds and metalloid hydrides,e.g., transition metal carbonyl, such as nickel carbonyl and diborane. Various sizes and shapes of deposits can be achieved, including near-net-shape free standing articles, multilayer deposits, and the like. Manipulation or absence of a magnetic field affects the nature and the structure of the deposit. 1 fig.

  13. Electrodeposition of amorphous ternary nickel-chromium-phosphorus alloy

    DOE Patents [OSTI]

    Guilinger, Terry R.

    1990-01-01

    Amorphous ternary nickel-chromium-phosphorus alloys are electrodeposited from a bath comprising a nickel salt, a chromium salt, a phosphorus source such as sodium hypophosphite, a complexing agent for the nickel ions, supporting salts to increase conductivity, and a buffering agent. The process is carried out at about room temperature and requires a current density between about 20 to 40 A/dm.sup.2.

  14. Formation of amorphous metal alloys by chemical vapor deposition

    DOE Patents [OSTI]

    Mullendore, Arthur W.

    1990-01-01

    Amorphous alloys are deposited by a process of thermal dissociation of mixtures or organometallic compounds and metalloid hydrides, e.g., transition metal carbonyl such as nickel carbonyl, and diborane. Various sizes and shapes of deposits can be achieved, including near-net-shape free standing articles, multilayer deposits, and the like. Manipulation or absence of a magnetic field affects the nature and the structure of the deposit.

  15. Final Report- 1366 Project Silicon: Reclaiming US Silicon PV Leadership

    Office of Energy Efficiency and Renewable Energy (EERE)

    1366 Technologies’ Project Silicon addresses two of the major goals of the DOE’s PV Manufacturing Initiative Part 2 program: 1) How to reclaim a strong silicon PV manufacturing presence and; 2) How to lower the levelized cost of electricity (“LCOE”) for solar to $0.05-$0.07/kWh, enabling wide-scale U.S. market adoption. To achieve these two goals, US companies must commercialize disruptive, high-value technologies that are capable of rapid scaling, defensible from foreign competition, and suited for US manufacturing. These are the aims of 1366 Technologies Direct Wafer ™ process.

  16. ThinSilicon | Open Energy Information

    Open Energy Info (EERE)

    ThinSilicon Place: California Product: US-based developer of thin-film PV module manufacturing technology. References: ThinSilicon1 This article is a stub. You can help OpenEI...

  17. Jiangshan Silicon Co Ltd | Open Energy Information

    Open Energy Info (EERE)

    China Zip: 134700 Product: Chinese metal silicon producer who is doing R&D to purify its silicon to 6N by UMG method Coordinates: 42.088902, 127.218193 Show Map Loading...

  18. NREL: Photovoltaics Research - Silicon Materials and Devices...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Top light blue layer has the text epi c-Si absorber. Schematic diagram of the film crystal silicon solar cell. A high-quality crystal silicon absorber is grown epitaxially on a ...

  19. Becancour Silicon Inc BSI | Open Energy Information

    Open Energy Info (EERE)

    to: navigation, search Name: Becancour Silicon Inc (BSI) Place: St. Laurent, Quebec, Canada Zip: H4M2M4 Sector: Solar Product: Canadian supplier of silicon metal for the...

  20. Enabling Thin Silicon Solar Cell Technology

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Enabling Thin Silicon Solar Cell Technology Enabling Thin Silicon Solar Cell Technology Print Friday, 21 June 2013 10:49 Generic silicon solar cells showing +45°, -45°, and dendritic crack patterns. The effort to shift U.S. energy reliance from fossil fuels to renewable sources has spurred companies to reduce the cost and increase the reliability of their solar photovoltaics (SPVs). The use of thinner silicon in SPV technologies is being widely adopted because it significantly reduces costs;

  1. Black Silicon Etching - Energy Innovation Portal

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Solar Photovoltaic Solar Photovoltaic Find More Like This Return to Search Black Silicon Etching Award-winning, efficient, and inexpensive photovoltaic technology National Renewable Energy Laboratory Contact NREL About This Technology Three silicon wafers, showing absorbed light: (left) micron-scale texture, (center) NREL&rsquo;s Black Silicon Etch, and (right) micron-scale texture with an antireflective coating. Three silicon wafers, showing absorbed light: (left) micron-scale texture,

  2. Copper doped polycrystalline silicon solar cell

    DOE Patents [OSTI]

    Lovelace, Alan M. Administrator of the National Aeronautics and Space; Koliwad, Krishna M.; Daud, Taher

    1981-01-01

    Photovoltaic cells having improved performance are fabricated from polycrystalline silicon containing copper segregated at the grain boundaries.

  3. Silicon nanocrystal inks, films, and methods

    DOE Patents [OSTI]

    Wheeler, Lance Michael; Kortshagen, Uwe Richard

    2015-09-01

    Silicon nanocrystal inks and films, and methods of making and using silicon nanocrystal inks and films, are disclosed herein. In certain embodiments the nanocrystal inks and films include halide-terminated (e.g., chloride-terminated) and/or halide and hydrogen-terminated nanocrystals of silicon or alloys thereof. Silicon nanocrystal inks and films can be used, for example, to prepare semiconductor devices.

  4. Crystalline Silicon Photovoltaics Research | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Crystalline Silicon Photovoltaics Research Crystalline Silicon Photovoltaics Research DOE supports crystalline silicon photovoltaic (PV) research and development efforts that lead to market-ready technologies. Below are a list of the projects, summary of the benefits, and discussion on the production and manufacturing of this solar technology. Background Crystalline silicon PV cells are the most common solar cells used in commercially available solar panels, representing 87% of world PV cell

  5. Silicon crystal growing by oscillating crucible technique

    DOE Patents [OSTI]

    Schwuttke, G.H.; Kim, K.M.; Smetana, P.

    1983-08-03

    A process for growing silicon crystals from a molten melt comprising oscillating the container during crystal growth is disclosed.

  6. System and method for liquid silicon containment

    DOE Patents [OSTI]

    Cliber, James A; Clark, Roger F; Stoddard, Nathan G; Von Dollen, Paul

    2013-05-28

    This invention relates to a system and a method for liquid silicon containment, such as during the casting of high purity silicon used in solar cells or solar modules. The containment apparatus includes a shielding member adapted to prevent breaching molten silicon from contacting structural elements or cooling elements of a casting device, and a volume adapted to hold a quantity of breaching molten silicon with the volume formed by a bottom and one or more sides.

  7. System and method for liquid silicon containment

    DOE Patents [OSTI]

    Cliber, James A; Clark, Roger F; Stoddard, Nathan G; Von Dollen, Paul

    2014-06-03

    This invention relates to a system and a method for liquid silicon containment, such as during the casting of high purity silicon used in solar cells or solar modules. The containment apparatus includes a shielding ember adapted to prevent breaching molten silicon from contacting structural elements or cooling elements of a casting device, and a volume adapted to hold a quantity of breaching molten silicon with the volume formed by a bottom and one or more sides.

  8. Probe of field collapse in a-Si:H solar cells

    SciTech Connect (OSTI)

    Wang, Q.; Crandall, R.S.

    1996-12-31

    The authors study the effect of illumination intensity on solar cell performance in a-Si:H solar cells. They find that the fill factor strongly depends on light intensity. As they increase the illumination intensity from low levels to one sun they observe a decrease in fill factor of approximately 15% in as grown cells. The authors attribute this effect to electric field collapse inside the cell. They propose that photogenerated space charge (free and trapped charge) increases with light intensity and causes field collapse. They describe the origin of space charge and the associated capacitance-photocapacitance. They measure the photocapacitance as a barometer to probe the collapsed field. The authors obtain a good agreement between photocapacitance experiments and theory. They also explore the light intensity dependence of photocapacitance and explain the decrease of FF with the increasing light intensity.

  9. Fabrication of a single layer graphene by copper intercalation on a SiC(0001) surface

    SciTech Connect (OSTI)

    Yagyu, Kazuma; Tochihara, Hiroshi; Tomokage, Hajime; Suzuki, Takayuki; Tajiri, Takayuki; Kohno, Atsushi; Takahashi, Kazutoshi

    2014-02-03

    Cu atoms deposited on a zero layer graphene grown on a SiC(0001) substrate, intercalate between the zero layer graphene and the SiC substrate after the thermal annealing above 600?C, forming a Cu-intercalated single layer graphene. On the Cu-intercalated single layer graphene, a graphene lattice with superstructure due to moir pattern is observed by scanning tunneling microscopy, and specific linear dispersion at the K{sup } point as well as a characteristic peak in a C{sub 1s} core level spectrum, which is originated from a free-standing graphene, is confirmed by photoemission spectroscopy. The Cu-intercalated single layer graphene is found to be n-doped.

  10. Laser wafering for silicon solar.

    SciTech Connect (OSTI)

    Friedmann, Thomas Aquinas; Sweatt, William C.; Jared, Bradley Howell

    2011-03-01

    Current technology cuts solar Si wafers by a wire saw process, resulting in 50% 'kerf' loss when machining silicon from a boule or brick into a wafer. We want to develop a kerf-free laser wafering technology that promises to eliminate such wasteful wire saw processes and achieve up to a ten-fold decrease in the g/W{sub p} (grams/peak watt) polysilicon usage from the starting polysilicon material. Compared to today's technology, this will also reduce costs ({approx}20%), embodied energy, and green-house gas GHG emissions ({approx}50%). We will use short pulse laser illumination sharply focused by a solid immersion lens to produce subsurface damage in silicon such that wafers can be mechanically cleaved from a boule or brick. For this concept to succeed, we will need to develop optics, lasers, cleaving, and high throughput processing technologies capable of producing wafers with thicknesses < 50 {micro}m with high throughput (< 10 sec./wafer). Wafer thickness scaling is the 'Moore's Law' of silicon solar. Our concept will allow solar manufacturers to skip entire generations of scaling and achieve grid parity with commercial electricity rates. Yet, this idea is largely untested and a simple demonstration is needed to provide credibility for a larger scale research and development program. The purpose of this project is to lay the groundwork to demonstrate the feasibility of laser wafering. First, to design and procure on optic train suitable for producing subsurface damage in silicon with the required damage and stress profile to promote lateral cleavage of silicon. Second, to use an existing laser to produce subsurface damage in silicon, and third, to characterize the damage using scanning electron microscopy and confocal Raman spectroscopy mapping.

  11. Process of preparing tritiated porous silicon

    DOE Patents [OSTI]

    Tam, Shiu-Wing

    1997-01-01

    A process of preparing tritiated porous silicon in which porous silicon is equilibrated with a gaseous vapor containing HT/T.sub.2 gas in a diluent for a time sufficient for tritium in the gas phase to replace hydrogen present in the pore surfaces of the porous silicon.

  12. Process of preparing tritiated porous silicon

    DOE Patents [OSTI]

    Tam, S.W.

    1997-02-18

    A process of preparing tritiated porous silicon is described in which porous silicon is equilibrated with a gaseous vapor containing HT/T{sub 2} gas in a diluent for a time sufficient for tritium in the gas phase to replace hydrogen present in the pore surfaces of the porous silicon. 1 fig.

  13. Prealloyed catalyst for growing silicon carbide whiskers

    DOE Patents [OSTI]

    Shalek, Peter D. (Los Alamos, NM); Katz, Joel D. (Niagara Falls, NY); Hurley, George F. (Los Alamos, NM)

    1988-01-01

    A prealloyed metal catalyst is used to grow silicon carbide whiskers, especially in the .beta. form. Pretreating the metal particles to increase the weight percentages of carbon or silicon or both carbon and silicon allows whisker growth to begin immediately upon reaching growth temperature.

  14. White-blue electroluminescence from a Si quantum dot hybrid light-emitting diode

    SciTech Connect (OSTI)

    Xin, Yunzi; Nishio, Kazuyuki; Saitow, Ken-ichi

    2015-05-18

    A silicon (Si) quantum dot (QD)-based hybrid inorganic/organic light-emitting diode (LED) was fabricated via solution processing. This device exhibited white-blue electroluminescence at a low applied voltage of 6?V, with 78% of the effective emission obtained from the Si QDs. This hybrid LED produced current and optical power densities 280 and 350 times greater than those previously reported for such device. The superior performance of this hybrid device was obtained by both the prepared Si QDs and the optimized layer structure and thereby improving carrier migration through the hybrid LED and carrier recombination in the homogeneous Si QD layer.

  15. Silicon carbide fibers and articles including same

    SciTech Connect (OSTI)

    Garnier, John E; Griffith, George W

    2015-01-27

    Methods of producing silicon carbide fibers. The method comprises reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500.degree. C. to approximately 2000.degree. C. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01.times.10.sup.2 Pascal to produce continuous alpha silicon carbide fibers. Continuous alpha silicon carbide fibers and articles formed from the continuous alpha silicon carbide fibers are also disclosed.

  16. Methods for producing silicon carbide fibers

    DOE Patents [OSTI]

    Garnier, John E.; Griffith, George W.

    2016-03-01

    Methods of producing silicon carbide fibers. The method comprises reacting a continuous carbon fiber material and a silicon-containing gas in a reaction chamber at a temperature ranging from approximately 1500.degree. C. to approximately 2000.degree. C. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01.times.10.sup.2 Pascal to produce continuous alpha silicon carbide fibers. Continuous alpha silicon carbide fibers and articles formed from the continuous alpha silicon carbide fibers are also disclosed.

  17. Silicon on insulator self-aligned transistors

    DOE Patents [OSTI]

    McCarthy, Anthony M.

    2003-11-18

    A method for fabricating thin-film single-crystal silicon-on-insulator (SOI) self-aligned transistors. Standard processing of silicon substrates is used to fabricate the transistors. Physical spaces, between the source and gate, and the drain and gate, introduced by etching the polysilicon gate material, are used to provide connecting implants (bridges) which allow the transistor to perform normally. After completion of the silicon substrate processing, the silicon wafer is bonded to an insulator (glass) substrate, and the silicon substrate is removed leaving the transistors on the insulator (glass) substrate. Transistors fabricated by this method may be utilized, for example, in flat panel displays, etc.

  18. Intermediate Bandgap Solar Cells From Nanostructured Silicon

    SciTech Connect (OSTI)

    Black, Marcie

    2014-10-30

    This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

  19. Dispersion toughened silicon carbon ceramics

    DOE Patents [OSTI]

    Wei, G.C.

    1984-01-01

    Fracture resistant silicon carbide ceramics are provided by incorporating therein a particulate dispersoid selected from the group consisting of (a) a mixture of boron, carbon and tungsten, (b) a mixture of boron, carbon and molybdenum, (c) a mixture of boron, carbon and titanium carbide, (d) a mixture of aluminum oxide and zirconium oxide, and (e) boron nitride. 4 figures.

  20. Microelectromechanical pump utilizing porous silicon

    DOE Patents [OSTI]

    Lantz, Jeffrey W.; Stalford, Harold L.

    2011-07-19

    A microelectromechanical (MEM) pump is disclosed which includes a porous silicon region sandwiched between an inlet chamber and an outlet chamber. The porous silicon region is formed in a silicon substrate and contains a number of pores extending between the inlet and outlet chambers, with each pore having a cross-section dimension about equal to or smaller than a mean free path of a gas being pumped. A thermal gradient is provided along the length of each pore by a heat source which can be an electrical resistance heater or an integrated circuit (IC). A channel can be formed through the silicon substrate so that inlet and outlet ports can be formed on the same side of the substrate, or so that multiple MEM pumps can be connected in series to form a multi-stage MEM pump. The MEM pump has applications for use in gas-phase MEM chemical analysis systems, and can also be used for passive cooling of ICs.

  1. Method for fabricating silicon cells

    DOE Patents [OSTI]

    Ruby, Douglas S.; Basore, Paul A.; Schubert, W. Kent

    1998-08-11

    A process for making high-efficiency solar cells. This is accomplished by forming a diffusion junction and a passivating oxide layer in a single high-temperature process step. The invention includes the class of solar cells made using this process, including high-efficiency solar cells made using Czochralski-grown silicon.

  2. Method for fabricating silicon cells

    DOE Patents [OSTI]

    Ruby, D.S.; Basore, P.A.; Schubert, W.K.

    1998-08-11

    A process is described for making high-efficiency solar cells. This is accomplished by forming a diffusion junction and a passivating oxide layer in a single high-temperature process step. The invention includes the class of solar cells made using this process, including high-efficiency solar cells made using Czochralski-grown silicon. 9 figs.

  3. Characterization of the Electronic Structure of Silicon Nanoparticles Using X-ray Absorption and Emission

    SciTech Connect (OSTI)

    Vaverka, A M

    2008-07-15

    Resolving open questions regarding transport in nanostructures can have a huge impact on a broad range of future technologies such as light harvesting for energy. Silicon has potential to be used in many of these applications. Understanding how the band edges of nanostructures move as a function of size, surface termination and assembly is of fundamental importance in understanding the transport properties of these materials. In this thesis work I have investigated the change in the electronic structure of silicon nanoparticle assemblies as the surface termination is changed. Nanoparticles are synthesized using a thermal evaporation technique and sizes are determined using atomic force microscopy (AFM). By passivating the particles with molecules containing alcohol groups we are able to modify the size dependent band edge shifts. Both the valence and conduction bands are measured using synchrotron based x-ray absorption spectroscopy (XAS) and soft x-ray fluorescence (SXF) techniques. Particles synthesized via recrystallization of amorphous silicon/SiO{sub 2} multilayers of thicknesses below 10 nm are also investigated using the synchrotron techniques. These samples also show quantum confinement effects but the electronic structure is different from those synthesized via evaporation methods. The total bandgap is determined for all samples measured. The origins of these differences in the electronic structures are discussed.

  4. Reciprocal space analysis of the microstructure of luminescent and nonluminescent porous silicon films

    SciTech Connect (OSTI)

    Lee, S.R.; Barbour, J.C.; Medernach, J.W.; Stevenson, J.O.; Custer, J.S.

    1994-12-31

    The microstructure of anodically prepared porous silicon films was determined using a novel X-ray diffraction technique. This technique uses double-crystal diffractometry combined with position-sensitive X- ray detection to efficiently and quantitatively image the reciprocal space structure of crystalline materials. Reciprocal space analysis of newly prepared, as well as aged, p{sup {minus}} porous silicon films showed that these films exhibit a very broad range of crystallinity. This material appears to range in structure from a strained, single-crystal, sponge-like material exhibiting long-range coherency to isolated, dilated nanocrystals embedded in an amorphous matrix. Reciprocal space analysis of n{sup +} and p{sup +} porous silicon showed these materials are strained single-crystals with a spatially-correlated array of vertical pores. The vertical pores in these crystals may be surrounded by nanoporous or nanocrystalline domains as small as a few nm in size which produce diffuse diffraction indicating their presence. The photoluminescence of these films was examined using 488 nm Ar laser excitation in order to search for possible correlations between photoluminescent intensity and crystalline microstructure.

  5. Self- and dopant diffusion in extrinsic boron doped isotopically controlled silicon multilayer structures

    SciTech Connect (OSTI)

    Sharp, Ian D.; Bracht, Hartmut A.; Silvestri, Hughes H.; Nicols, Samuel P.; Beeman, Jeffrey W.; Hansen, John L.; Nylandsted Larsen, Arne; Haller, Eugene E.

    2002-04-01

    Isotopically controlled silicon multilayer structures were used to measure the enhancement of self- and dopant diffusion in extrinsic boron doped silicon. {sup 30}Si was used as a tracer through a multilayer structure of alternating natural Si and enriched {sup 28}Si layers. Low energy, high resolution secondary ion mass spectrometry (SIMS) allowed for simultaneous measurement of self- and dopant diffusion profiles of samples annealed at temperatures between 850 C and 1100 C. A specially designed ion- implanted amorphous Si surface layer was used as a dopant source to suppress excess defects in the multilayer structure, thereby eliminating transient enhanced diffusion (TED) behavior. Self- and dopant diffusion coefficients, diffusion mechanisms, and native defect charge states were determined from computer-aided modeling, based on differential equations describing the diffusion processes. We present a quantitative description of B diffusion enhanced self-diffusion in silicon and conclude that the diffusion of both B and Si is mainly mediated by neutral and singly positively charged self-interstitials under p-type doping. No significant contribution of vacancies to either B or Si diffusion is observed.

  6. Epitaxial growth of silicon for layer transfer

    DOE Patents [OSTI]

    Teplin, Charles; Branz, Howard M

    2015-03-24

    Methods of preparing a thin crystalline silicon film for transfer and devices utilizing a transferred crystalline silicon film are disclosed. The methods include preparing a silicon growth substrate which has an interface defining substance associated with an exterior surface. The methods further include depositing an epitaxial layer of silicon on the silicon growth substrate at the surface and separating the epitaxial layer from the substrate substantially along the plane or other surface defined by the interface defining substance. The epitaxial layer may be utilized as a thin film of crystalline silicon in any type of semiconductor device which requires a crystalline silicon layer. In use, the epitaxial transfer layer may be associated with a secondary substrate.

  7. Amorphization of nanocrystalline 3C-SiC irradiated with Si+ ions...

    Office of Scientific and Technical Information (OSTI)

    amorphization. Authors: Jiang, Weilin ; Wang, Haiyan ; Kim, Ickchan ; Zhang, Yanwen ; Weber, William J. Publication Date: 2010-11-23 OSTI Identifier: 994026 Report Number(s): ...

  8. Solid state amorphization of nanocrystalline nickel by cryogenic laser shock peening

    SciTech Connect (OSTI)

    Ye, Chang Ren, Zhencheng; Zhao, Jingyi; Hou, Xiaoning; Dong, Yalin; Liu, Yang; Sang, Xiahan

    2015-10-07

    In this study, complete solid state amorphization in nanocrystalline nickel has been achieved through cryogenic laser shock peening (CLSP). High resolution transmission electron microscopy has revealed the complete amorphous structure of the sample after CLSP processing. A molecular dynamic model has been used to investigate material behavior during the shock loading and the effects of nanoscale grain boundaries on the amorphization process. It has been found that the initial nanoscale grain boundaries increase the initial Gibbs free energy before plastic deformation and also serve as dislocation emission sources during plastic deformation to contribute to defect density increase, leading to the amorphization of pure nanocrystalline nickel.

  9. Semiconductor device PN junction fabrication using optical processing of amorphous semiconductor material

    DOE Patents [OSTI]

    Sopori, Bhushan; Rangappan, Anikara

    2014-11-25

    Systems and methods for semiconductor device PN junction fabrication are provided. In one embodiment, a method for fabricating an electrical device having a P-N junction comprises: depositing a layer of amorphous semiconductor material onto a crystalline semiconductor base, wherein the crystalline semiconductor base comprises a crystalline phase of a same semiconductor as the amorphous layer; and growing the layer of amorphous semiconductor material into a layer of crystalline semiconductor material that is epitaxially matched to the lattice structure of the crystalline semiconductor base by applying an optical energy that penetrates at least the amorphous semiconductor material.

  10. Preparation and uses of amorphous boron carbide coated substrates

    DOE Patents [OSTI]

    Riley, R.E.; Newkirk, L.R.; Valencia, F.A.; Wallace, T.C.

    1979-12-05

    Cloth is coated at a temperature below about 1000/sup 0/C with amorphous boron-carbon deposits in a process which provides a substantially uniform coating on all the filaments making up each yarn fiber bundle of the cloth. The coated cloths can be used in the as-deposited condition for example as wear surfaces where high hardness values are needed; or multiple layers of coated cloths can be hot-pressed to form billets useful for example in fusion reactor wall armor. Also provided is a method of controlling the atom ratio of B:C of boron-carbon deposits onto any of a variety of substrates, including cloths.

  11. Preparation and uses of amorphous boron carbide coated substrates

    DOE Patents [OSTI]

    Riley, Robert E.; Newkirk, Lawrence R.; Valencia, Flavio A.

    1981-09-01

    Cloth is coated at a temperature below about 1000.degree. C. with amorphous boron-carbon deposits in a process which provides a substantially uniform coating on all the filaments making up each yarn fiber bundle of the cloth. The coated cloths can be used in the as-deposited condition for example as wear surfaces where high hardness values are needed; or multiple layers of coated cloths can be hot-pressed to form billets useful for example in fusion reactor wall armor. Also provided is a method of controlling the atom ratio of B:C of boron-carbon deposits onto any of a variety of substrates, including cloths.

  12. D0 Silicon Upgrad: D0 Silicon Cooling System

    SciTech Connect (OSTI)

    Squires, B.; /Fermilab

    1998-07-14

    The cooling system design is not complete. This paper lays out the general design and some of the design calculations that have been performed up to this date. Further refinement will be performed. This is especially true in the piping layout, piping insulation and detector manifold areas. The silicon detector is cooled by means of a coolant in the beryllium channels that also act as the primary supporting device for the silicon ladders and wedges. The coolant is water with ethylene glycol added as a freezing point depressant. The glycol concentration in the coolant is 30% by weight resulting in a freezing point of approximately -15 C. If the water/glycol is not sufficient for maintaining the desired detector temperature the concentration of the water/glycol may be changed or an alternative coolant may be used.

  13. Effect of Dual-Function Nano-Structured Silicon Oxide Thin Film on Multi-Junction Solar Cells

    SciTech Connect (OSTI)

    Yan, B.; Sivec, L.; Yue, G.; Jiang, C. S.; Yang, J.; Guha, S.

    2011-01-01

    We present our recent study of using nano-structured hydrogenated silicon oxide films (nc-SiO{sub x}:H) as a dual-function layer in multi-junction solar cells. The nc-SiO{sub x}:H films were deposited using very high frequency glow discharge of a SiH{sub 4} (or Si{sub 2}H{sub 6}), CO{sub 2}, PH{sub 3}, and H{sub 2} gas mixture. By optimizing deposition parameters, we obtained 'dual function' nc-SiO{sub x}:H material characterized by a conductivity suitable for use as an n layer and optical properties suitable for use as an inter-reflection layer. We tested the nc-SiO{sub x}:H by replacing the normal n-type material in the tunnel junction of a multi-junction structure. The advantage of the dual-function nc-SiO{sub x}:H layer is twofold; one is to simplify the cell structure, and the other is to reduce any optical loss associated with the inter-reflection layer. Quantum efficiency measurements show the gain in top cell current is equal to or greater than the loss in bottom cell current for a-Si:H/nc-Si:H structures. In addition, a thinner a-Si:H top cell with the nc-SiO{sub x}:H n layer improves the top-cell stability, thereby providing higher stabilized solar cell efficiency. We also used the dual-function layer between the middle and the bottom cells in a-Si:H/a-SiGe:H/nc-Si:H triple-junction structures. The gain in the middle cell current is {approx}1.0 mA/cm{sup 2}, leading to an initial active-area efficiency of 14.8%.

  14. Evaluation of transition metal oxide as carrier-selective contacts for silicon heterojunction solar cells

    SciTech Connect (OSTI)

    Ding, L.; Boccard, Matthieu; Holman, Zachary; Bertoni, M.

    2015-04-06

    "Reducing light absorption in the non-active solar cell layers, while enabling the extraction of the photogenerated minority carriers at quasi-Fermi levels are two key factors to improve current generation and voltage, and therefore efficiency of silicon heterojunction solar devices. To address these two critical aspects, transition metal oxide materials have been proposed as alternative to the n- and p-type amorphous silicon used as electron and hole selective contacts, respectively. Indeed, transition metal oxides such as molybdenum oxide, titanium oxide, nickel oxide or tungsten oxide combine a wide band gap typically over 3 eV with a band structure and theoretical band alignment with silicon that results in high transparency to the solar spectrum and in selectivity for the transport of only one carrier type. Improving carrier extraction or injection using transition metal oxide has been a topic of investigation in the field of organic solar cells and organic LEDs; from these pioneering works a lot of knowledge has been gained on materials properties, ways to control these during synthesis and deposition, and their impact on device performance. Recently, the transfer of some of this knowledge to silicon solar cells and the successful application of some metal oxide to contact heterojunction devices have gained much attention. In this contribution, we investigate the suitability of various transition metal oxide films (molybdenum oxide, titanium oxide, and tungsten oxide) deposited either by thermal evaporation or sputtering as transparent hole or electron selective transport layer for silicon solar cells. In addition to systematically characterize their optical and structural properties, we use photoemission spectroscopy to relate compound stoichiometry to band structure and characterize band alignment to silicon. The direct silicon/metal oxide interface is further analyzed by quasi-steady state photoconductance decay method to assess the quality of surface

  15. A SiC MOSFET Based Inverter for Wireless Power Transfer Applications

    SciTech Connect (OSTI)

    Onar, Omer C; Chinthavali, Madhu Sudhan; Campbell, Steven L; Ning, Puqi; White, Cliff P; Miller , John M.

    2014-01-01

    In a wireless power transfer (WPT) system, efficiency of the power conversion stages is crucial so that the WPT technology can compete with the conventional conductive charging systems. Since there are 5 or 6 power conversion stages, each stage needs to be as efficient as possible. SiC inverters are crucial in this case; they can handle high frequency operation and they can operate at relatively higher temperatures resulting in reduces cost and size for the cooling components. This study presents the detailed power module design, development, and fabrication of a SiC inverter. The proposed inverter has been tested at three center frequencies that are considered for the WPT standardization. Performance of the inverter at the same target power transfer level is analyzed along with the other system components. In addition, another SiC inverter has been built in authors laboratory by using the ORNL designed and developed SiC modules. It is shown that the inverter with ORNL packaged SiC modules performs simular to that of the inverter having commercially available SiC modules.

  16. Growth mechanism of polycrystalline silicon films from hydrogen-diluted SiCl{sub 4} at low temperature

    SciTech Connect (OSTI)

    Lin Xuanying; Lin Kuixun; Huang Chuajun; Yu Yunpeng; Luo Yilin; Yu Chuying; Huang Rui

    2005-08-01

    The growth process of polycrystalline silicon films fabricated at 200 deg. C by radio-frequency glow discharge plasma-enhanced chemical-vapor deposition technique from hydrogen-diluted SiCl{sub 4} has been investigated. We analyze the changes of crystallinity and crystalline grain size with the depth from the top surface of the film through studying the depth profiles of the Raman spectra. The results show that the top surface is composed of silicon nanometer crystalline grains and the clustered amorphous silicon. The component of crystalline phase increases with the increase in depth. Moreover, the film crystallization structure depends strongly on the power. On the other hand, it is almost independent of the substrate temperature and the annealing temperature. Comparing with the growth processes of polycrystalline silicon films from hydrogen-diluted SiH{sub 4}, it is considered that the formation of nanometer size grains occurs in the gas phase reaction process at the initial stage of film growth, while the grain growth is largely governed by the surface reaction process where in the chlorine element plays an important role.

  17. Low-temperature thermal expansion of amorphous solids

    SciTech Connect (OSTI)

    Ackerman, David Alan

    1982-01-01

    For most amorphous materials at temperatures below approx. = 1 K, the magnitudes and temperature dependences of specific heat, thermal conductivity and ultrasonic dispersion are qualitatively similar, independent of chemical composition. It has been suggested that thermal expansion also exhibits this universal behavior. The development of a dilatometer capable of resolving sample strains as small as 10/sup -12/ has permitted measurement of the linear thermal expansion of various glasses below 1 K. These investigations have demonstrated, however, that the low-temperature thermal expansion coefficient of glasses can be positive, negative, large or small. Analysis of measurements performed on two types of vitreous silica, two amorphous polymers, As/sub 2/S/sub 3/ and ZrO/sub 2/:Y/sub 2/O/sub 3/ is presented in the context of the phenomenological tunneling-states model. Consistency in explanation of thermal expansion and ultrasonic behavior is maintained by assuming a broad, weakly energy-dependent distribution of coupling strengths between phonons and the localized excitations thought to be characteristic of the glassy state.

  18. On coarse projective integration for atomic deposition in amorphous systems

    SciTech Connect (OSTI)

    Chuang, Claire Y. E-mail: meister@unm.edu Sinno, Talid; Han, Sang M. E-mail: meister@unm.edu; Zepeda-Ruiz, Luis A. E-mail: meister@unm.edu

    2015-10-07

    Direct molecular dynamics simulation of atomic deposition under realistic conditions is notoriously challenging because of the wide range of time scales that must be captured. Numerous simulation approaches have been proposed to address the problem, often requiring a compromise between model fidelity, algorithmic complexity, and computational efficiency. Coarse projective integration, an example application of the “equation-free” framework, offers an attractive balance between these constraints. Here, periodically applied, short atomistic simulations are employed to compute time derivatives of slowly evolving coarse variables that are then used to numerically integrate differential equations over relatively large time intervals. A key obstacle to the application of this technique in realistic settings is the “lifting” operation in which a valid atomistic configuration is recreated from knowledge of the coarse variables. Using Ge deposition on amorphous SiO{sub 2} substrates as an example application, we present a scheme for lifting realistic atomistic configurations comprised of collections of Ge islands on amorphous SiO{sub 2} using only a few measures of the island size distribution. The approach is shown to provide accurate initial configurations to restart molecular dynamics simulations at arbitrary points in time, enabling the application of coarse projective integration for this morphologically complex system.

  19. Developing a High Thermal Conductivity Fuel with Silicon Carbide Additives

    SciTech Connect (OSTI)

    baney, Ronald; Tulenko, James

    2012-11-20

    The objective of this research is to increase the thermal conductivity of uranium oxide (UO{sub 2}) without significantly impacting its neutronic properties. The concept is to incorporate another high thermal conductivity material, silicon carbide (SiC), in the form of whiskers or from nanoparticles of SiC and a SiC polymeric precursor into UO{sub 2}. This is expected to form a percolation pathway lattice for conductive heat transfer out of the fuel pellet. The thermal conductivity of SiC would control the overall fuel pellet thermal conductivity. The challenge is to show the effectiveness of a low temperature sintering process, because of a UO{sub 2}-SiC reaction at 1,377°C, a temperature far below the normal sintering temperature. Researchers will study three strategies to overcome the processing difficulties associated with pore clogging and the chemical reaction of SiC and UO{sub 2} at temperatures above 1,300°C:

  20. Supersonic Dislocation Bursts in Silicon

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hahn, E. N.; Zhao, S.; Bringa, E. M.; Meyers, M. A.

    2016-06-06

    Dislocations are the primary agents of permanent deformation in crystalline solids. Since the theoretical prediction of supersonic dislocations over half a century ago, there is a dearth of experimental evidence supporting their existence. Here we use non-equilibrium molecular dynamics simulations of shocked silicon to reveal transient supersonic partial dislocation motion at approximately 15 km/s, faster than any previous in-silico observation. Homogeneous dislocation nucleation occurs near the shock front and supersonic dislocation motion lasts just fractions of picoseconds before the dislocations catch the shock front and decelerate back to the elastic wave speed. Applying a modified analytical equation for dislocation evolutionmore » we successfully predict a dislocation density of 1.5 x 10(12) cm(-2) within the shocked volume, in agreement with the present simulations and realistic in regards to prior and on-going recovery experiments in silicon.« less

  1. Formation of multiple levels of porous silicon for buried insulators and conductors in silicon device technologies

    DOE Patents [OSTI]

    Blewer, Robert S.; Gullinger, Terry R.; Kelly, Michael J.; Tsao, Sylvia S.

    1991-01-01

    A method of forming a multiple level porous silicon substrate for semiconductor integrated circuits including anodizing non-porous silicon layers of a multi-layer silicon substrate to form multiple levels of porous silicon. At least one porous silicon layer is then oxidized to form an insulating layer and at least one other layer of porous silicon beneath the insulating layer is metallized to form a buried conductive layer. Preferably the insulating layer and conductive layer are separated by an anodization barrier formed of non-porous silicon. By etching through the anodization barrier and subsequently forming a metallized conductive layer, a fully or partially insulated buried conductor may be fabricated under single crystal silicon.

  2. Analytical and Experimental Evaluation of Joining Silicon Carbide to Silicon Carbide and Silicon Nitride to Silicon Nitride for Advanced Heat Engine Applications Phase II

    SciTech Connect (OSTI)

    Sundberg, G.J.

    1994-01-01

    Techniques were developed to produce reliable silicon nitride to silicon nitride (NCX-5101) curved joins which were used to manufacture spin test specimens as a proof of concept to simulate parts such as a simple rotor. Specimens were machined from the curved joins to measure the following properties of the join interlayer: tensile strength, shear strength, 22 C flexure strength and 1370 C flexure strength. In parallel, extensive silicon nitride tensile creep evaluation of planar butt joins provided a sufficient data base to develop models with accurate predictive capability for different geometries. Analytical models applied satisfactorily to the silicon nitride joins were Norton's Law for creep strain, a modified Norton's Law internal variable model and the Monkman-Grant relationship for failure modeling. The Theta Projection method was less successful. Attempts were also made to develop planar butt joins of siliconized silicon carbide (NT230).

  3. A nonlinear lag correction algorithm for a-Si flat-panel x-ray detectors

    SciTech Connect (OSTI)

    Starman, Jared; Star-Lack, Josh; Virshup, Gary; Shapiro, Edward; Fahrig, Rebecca

    2012-10-15

    Purpose: Detector lag, or residual signal, in a-Si flat-panel (FP) detectors can cause significant shading artifacts in cone-beam computed tomography reconstructions. To date, most correction models have assumed a linear, time-invariant (LTI) model and correct lag by deconvolution with an impulse response function (IRF). However, the lag correction is sensitive to both the exposure intensity and the technique used for determining the IRF. Even when the LTI correction that produces the minimum error is found, residual artifact remains. A new non-LTI method was developed to take into account the IRF measurement technique and exposure dependencies. Methods: First, a multiexponential (N = 4) LTI model was implemented for lag correction. Next, a non-LTI lag correction, known as the nonlinear consistent stored charge (NLCSC) method, was developed based on the LTI multiexponential method. It differs from other nonlinear lag correction algorithms in that it maintains a consistent estimate of the amount of charge stored in the FP and it does not require intimate knowledge of the semiconductor parameters specific to the FP. For the NLCSC method, all coefficients of the IRF are functions of exposure intensity. Another nonlinear lag correction method that only used an intensity weighting of the IRF was also compared. The correction algorithms were applied to step-response projection data and CT acquisitions of a large pelvic phantom and an acrylic head phantom. The authors collected rising and falling edge step-response data on a Varian 4030CB a-Si FP detector operating in dynamic gain mode at 15 fps at nine incident exposures (2.0%-92% of the detector saturation exposure). For projection data, 1st and 50th frame lag were measured before and after correction. For the CT reconstructions, five pairs of ROIs were defined and the maximum and mean signal differences within a pair were calculated for the different exposures and step-response edge techniques. Results: The LTI

  4. Channeling, Volume Reection and Gamma Emission Using 14GeV Electrons in Bent Silicon Crystals

    SciTech Connect (OSTI)

    Benson, Brandon

    2015-08-14

    High energy electrons can be deflected with very tight bending radius using a bent silicon crystal. This produces gamma radiation. As these crystals can be thin, a series of bent silicon crystals with alternating direction has the potential to produce coherent gamma radiation with reasonable energy of the driving electron beam. Such an electron crystal undulator offers the prospect for higher energy radiation at lower cost than current methods. Permanent magnetic undulators like LCLS at SLAC National Accelerator Laboratory are expensive and very large (about 100 m in case of the LCLS undulator). Silicon crystals are inexpensive and compact when compared to the large magnetic undulators. Additionally, such a high energy coherent light source could be used for probing through materials currently impenetrable by x-rays. In this work we present the experimental data and analysis of experiment T523 conducted at SLAC National Accelerator Laboratory. We collected the spectrum of gamma ray emission from 14 GeV electrons on a bent silicon crystal counting single photons. We also investigated the dynamics of electron motion in the crystal i.e. processes of channeling and volume reflection at 14 GeV, extending and building off previous work. Our single photon spectrum for the amorphous crystal orientation is consistent with bremsstrahlung radiation and the volume reflection crystal orientation shows a trend consistent with synchrotron radiation at a critical energy of 740 MeV. We observe that in these two cases the data are consistent, but we make no further claims because of statistical limitations. We also extended the known energy range of electron crystal dechanneling length and channeling efficiency to 14 GeV.

  5. Method for fabricating pixelated silicon device cells

    SciTech Connect (OSTI)

    Nielson, Gregory N.; Okandan, Murat; Cruz-Campa, Jose Luis; Nelson, Jeffrey S.; Anderson, Benjamin John

    2015-08-18

    A method, apparatus and system for flexible, ultra-thin, and high efficiency pixelated silicon or other semiconductor photovoltaic solar cell array fabrication is disclosed. A structure and method of creation for a pixelated silicon or other semiconductor photovoltaic solar cell array with interconnects is described using a manufacturing method that is simplified compared to previous versions of pixelated silicon photovoltaic cells that require more microfabrication steps.

  6. Process for strengthening silicon based ceramics

    DOE Patents [OSTI]

    Kim, Hyoun-Ee; Moorhead, A. J.

    1993-04-06

    A process for strengthening silicon based ceramic monolithic materials and omposite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400.degree. C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts , or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

  7. Laser, Supercomputer Measure Speedy Electrons in Silicon

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laser, Supercomputer Measure Speedy Electrons in Silicon Laser, Supercomputer Measure Speedy Electrons in Silicon Simulations at NERSC Help Illuminate Attosecond Laser Experiment Findings December 19, 2014 Contact: Robert Sanders, rlsanders@berkeley.edu, (510) 643-6998 speedyelectrons In silicon, electrons attached to atoms in the crystal lattice can be mobilized into the conduction band by light or voltage. Berkeley scientists have taken snapshots of this very brief band-gap jump and timed it

  8. Process for strengthening silicon based ceramics

    DOE Patents [OSTI]

    Kim, Hyoun-Ee; Moorhead, A. J.

    1993-01-01

    A process for strengthening silicon based ceramic monolithic materials and omposite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400.degree. C. The process results in a dense, tightly adherent silicon containing oxide layer that heals, blunts , or otherwise negates the detrimental effect of strength limiting flaws on the surface of the ceramic body.

  9. Evaluation of an aSi-EPID with flattening filter free beams: Applicability to the GLAaS algorithm for portal dosimetry and first experience for pretreatment QA of RapidArc

    SciTech Connect (OSTI)

    Nicolini, G.; Clivio, A.; Vanetti, E.; Cozzi, L.; Fogliata, A.; Krauss, H.; Fenoglietto, P.

    2013-11-15

    Purpose: To demonstrate the feasibility of portal dosimetry with an amorphous silicon mega voltage imager for flattening filter free (FFF) photon beams by means of the GLAaS methodology and to validate it for pretreatment quality assurance of volumetric modulated arc therapy (RapidArc).Methods: The GLAaS algorithm, developed for flattened beams, was applied to FFF beams of nominal energy of 6 and 10 MV generated by a Varian TrueBeam (TB). The amorphous silicon electronic portal imager [named mega voltage imager (MVI) on TB] was used to generate integrated images that were converted into matrices of absorbed dose to water. To enable GLAaS use under the increased dose-per-pulse and dose-rate conditions of the FFF beams, new operational source-detector-distance (SDD) was identified to solve detector saturation issues. Empirical corrections were defined to account for the shape of the profiles of the FFF beams to expand the original methodology of beam profile and arm backscattering correction. GLAaS for FFF beams was validated on pretreatment verification of RapidArc plans for three different TB linacs. In addition, the first pretreatment results from clinical experience on 74 arcs were reported in terms of ? analysis.Results: MVI saturates at 100 cm SDD for FFF beams but this can be avoided if images are acquired at 150 cm for all nominal dose rates of FFF beams. Rotational stability of the gantry-imager system was tested and resulted in a minimal apparent imager displacement during rotation of 0.2 0.2 mm at SDD = 150 cm. The accuracy of this approach was tested with three different Varian TrueBeam linacs from different institutes. Data were stratified per energy and machine and showed no dependence with beam quality and MLC model. The results from clinical pretreatment quality assurance, provided a gamma agreement index (GAI) in the field area for six and ten FFF beams of (99.8 0.3)% and (99.5 0.6)% with distance to agreement and dose difference criteria set

  10. Structural alloy with a protective coating containing silicon or silicon-oxide

    DOE Patents [OSTI]

    Natesan, K.

    1992-01-01

    This invention is comprised of an iron-based alloy containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100{degrees}C.

  11. Structural alloy with a protective coating containing silicon or silicon-oxide

    DOE Patents [OSTI]

    Natesan, K.

    1994-12-27

    An iron-based alloy is described containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100 C. 8 figures.

  12. Structural alloy with a protective coating containing silicon or silicon-oxide

    DOE Patents [OSTI]

    Natesan, Ken

    1994-01-01

    An iron-based alloy containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100.degree. C.

  13. Silicon Materials and Devices (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2013-06-01

    This National Center for Photovoltaics sheet describes the capabilities of its silicon materials and devices research. The scope and core competencies and capabilities are discussed.

  14. Hydrogenation of Dislocation-Limited Heteroepitaxial Silicon...

    Office of Scientific and Technical Information (OSTI)

    Hydrogenation of Dislocation- Limited Heteroepitaxial Silicon Solar Cells Preprint Michael L. Bolen, Sachit Grover, Charles W. Teplin, Howard M. Branz, and Paul Stradins National...

  15. Silicon nitride having a high tensile strength

    DOE Patents [OSTI]

    Pujari, Vimal K.; Tracey, Dennis M.; Foley, Michael R.; Paille, Norman I.; Pelletier, Paul J.; Sales, Lenny C.; Willkens, Craig A.; Yeckley, Russell L.

    1998-01-01

    A ceramic body comprising at least about 80 w/o silicon nitride and having a mean tensile strength of at least about 800 MPa.

  16. Silicon Valley Biodiesel Inc | Open Energy Information

    Open Energy Info (EERE)

    Biodiesel Inc Jump to: navigation, search Name: Silicon Valley Biodiesel Inc. Place: Sunnyvale, California Zip: CA 94086 Product: Manufactures biodiesel for the local diesel fuel...

  17. Norwegian Silicon Refining AS | Open Energy Information

    Open Energy Info (EERE)

    214 Product: Oslo-based company with an upgraded metallurgical silicon (UMG) production process called the Stubergh method. Coordinates: 59.91228, 10.74998 Show Map Loading...

  18. Silicon Materials and Devices (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2011-06-01

    Capabilities fact sheet for the National Center for Photovoltaics: Silicon Materials and Devices that includes scope, core competencies and capabilities, and contact/web information.

  19. Hydrogenation of Dislocation-Limited Heteroepitaxial Silicon...

    Office of Scientific and Technical Information (OSTI)

    Hydrogenation of Dislocation-Limited Heteroepitaxial Silicon Solar Cells: Preprint Bolen, M. L.; Grover, S.; Teplin, C. W.; Bobela, D.; Branz, H. M.; Stradins, P. 08 HYDROGEN; 14...

  20. Apparatus for obtaining silicon from fluosilicic acid

    DOE Patents [OSTI]

    Sanjurjo, Angel

    1986-05-20

    Apparatus for producing low cost, high purity solar grade silicon ingots in single crystal or quasi single crystal ingot form in a substantially continuous operation in a two stage reactor starting with sodium fluosilicate and a metal more electropositive than silicon (preferably sodium) in separate compartments having easy vapor transport therebetween and thermally decomposing the sodium fluosilicate to cause formation of substantially pure silicon and a metal fluoride which may be continuously separated in the melt and silicon may be directly and continuously cast from the melt.

  1. RSI Silicon Products LLC | Open Energy Information

    Open Energy Info (EERE)

    startup which is developing a process for solar-grade silicon manufacture at low energy intensity, spinoff from MIT. Coordinates: 47.237806, -121.179542 Show Map...

  2. Solar cell with silicon oxynitride dielectric layer

    SciTech Connect (OSTI)

    Shepherd, Michael; Smith, David D

    2015-04-28

    Solar cells with silicon oxynitride dielectric layers and methods of forming silicon oxynitride dielectric layers for solar cell fabrication are described. For example, an emitter region of a solar cell includes a portion of a substrate having a back surface opposite a light receiving surface. A silicon oxynitride (SiO.sub.xN.sub.y, 0silicon oxynitride dielectric layer.

  3. Process for Polycrystalline film silicon growth

    DOE Patents [OSTI]

    Wang, Tihu (Littleton, CO); Ciszek, Theodore F. (Evergreen, CO)

    2001-01-01

    A process for depositing polycrystalline silicon on substrates, including foreign substrates, occurs in a chamber at about atmospheric pressure, wherein a temperature gradient is formed, and both the atmospheric pressure and the temperature gradient are maintained throughout the process. Formation of a vapor barrier within the chamber that precludes exit of the constituent chemicals, which include silicon, iodine, silicon diiodide, and silicon tetraiodide. The deposition occurs beneath the vapor barrier. One embodiment of the process also includes the use of a blanketing gas that precludes the entrance of oxygen or other impurities. The process is capable of repetition without the need to reset the deposition zone conditions.

  4. Purified silicon production system - Energy Innovation Portal

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Transmission Energy Analysis Energy Storage Geothermal Hydrogen and Fuel Cell ... Return to Search Purified silicon production system United States Patent Patent ...

  5. Fuyuan Silicon Co Ltd | Open Energy Information

    Open Energy Info (EERE)

    Fuyuan Silicon Co Ltd Place: Baishan, Jilin Province, China Sector: Solar Product: A Chinese solar-grade polysilicon producer using metallurgical method. Coordinates:...

  6. Sunsing Silicon Inc | Open Energy Information

    Open Energy Info (EERE)

    Sunsing Silicon Inc Place: Liancheng, Fujian Province, China Zip: 366200 Product: A Chinese polysilicon manufacturer applying self-developed metallurgical method References:...

  7. Non-crosslinked, amorphous, block copolymer electrolyte for batteries

    DOE Patents [OSTI]

    Mayes, Anne M.; Ceder, Gerbrand; Chiang, Yet-Ming; Sadoway, Donald R.; Aydinol, Mehmet K.; Soo, Philip P.; Jang, Young-Il; Huang, Biying

    2006-04-11

    Solid battery components are provided. A block copolymeric electrolyte is non-crosslinked and non-glassy through the entire range of typical battery service temperatures, that is, through the entire range of at least from about 0.degree. C. to about 70.degree. C. The chains of which the copolymer is made each include at least one ionically-conductive block and at least one second block immiscible with the ionically-conductive block. The chains form an amorphous association and are arranged in an ordered nanostructure including a continuous matrix of amorphous ionically-conductive domains and amorphous second domains that are immiscible with the ionically-conductive domains. A compound is provided that has a formula of Li.sub.xM.sub.yN.sub.zO.sub.2. M and N are each metal atoms or a main group elements, and x, y and z are each numbers from about 0 to about 1. y and z are chosen such that a formal charge on the M.sub.yN.sub.z portion of the compound is (4-x). In certain embodiments, these compounds are used in the cathodes of rechargeable batteries. The present invention also includes methods of predicting the potential utility of metal dichalgogenide compounds for use in lithium intercalation compounds. It also provides methods for processing lithium intercalation oxides with the structure and compositional homogeneity necessary to realize the increased formation energies of said compounds. An article is made of a dimensionally-stable, interpenetrating microstructure of a first phase including a first component and a second phase, immiscible with the first phase, including a second component. The first and second phases define interphase boundaries between them, and at least one particle is positioned between a first phase and a second phase at an interphase boundary. When the first and second phases are electronically-conductive and ionically-conductive polymers, respectively, and the particles are ion host particles, the arrangement is an electrode of a battery.

  8. Nano tech Silicon India Ltd | Open Energy Information

    Open Energy Info (EERE)

    tech Silicon India Ltd Jump to: navigation, search Name: Nano-tech Silicon India Ltd Place: Hyderabad, Andhra Pradesh, India Product: Nano-tech Silicon is a manufacturer of PV...

  9. Materials and Electrical Characterization of Physical Vapor Deposited LaxLu1-xO3 Thin Films on 300 mm Silicon

    SciTech Connect (OSTI)

    L Edge; T Vo; V Paruchuri; R Iijima; J Bruley; J Jordan-Sweet; B Linder; A Kellock; T Tsunoda; S Shinde

    2011-12-31

    La{sub x}Lu{sub 1-x}O{sub 3} thin films were deposited on 300 mm silicon wafers by physical vapor deposition and fabricated into field-effect transistors using a gate-first process flow. The films were characterized using transmission electron microscopy, Rutherford backscattering spectrometry, and synchrotron x-ray diffraction. The results show the films remain amorphous even at temperatures of 1000 C. The dielectric properties of La{sub x}Lu{sub 1-x}O{sub 3} (0.125 {<=} x {<=} 0.875) thin films were evaluated as a function of film composition. The amorphous La{sub x}Lu{sub 1-x}O{sub 3} thin films have a dielectric constant (K) of 23 across the composition range. The inversion thickness (T{sub inv}) of the La{sub x}Lu{sub 1-x}O{sub 3} thin films was scaled to <1.0 nm.

  10. Structural and electronic properties of dense liquid and amorphous nitrogen

    SciTech Connect (OSTI)

    Boates, B; Bonev, S A

    2011-02-11

    We present first-principles calculations of the structural and electronic properties of liquid nitrogen in the pressure-temperature range of 0-200 GPa and 2000-6000 K. The molecular-polymerization and molecular-atomic liquid phase boundaries have been mapped over this region. We find the polymeric liquid to be metallic, similar to what has been reported for the higher-temperature atomic fluid. An explanation of the electronic properties is given based on the structure and bonding character of the transformed liquids. We discuss the structural and bonding differences between the polymeric liquid and insulating solid cubic-gauche nitrogen to explain the differences in their electronic properties. Furthermore, we discuss the mechanism responsible for charge transport in polymeric nitrogen systems to explain the conductivity of the polymeric fluid and the semi-conducting nature of low-temperature amorphous nitrogen.

  11. The sticking of atomic hydrogen on amorphous water ice

    SciTech Connect (OSTI)

    Veeraghattam, Vijay K.; Manrodt, Katie; Lewis, Steven P.; Stancil, P. C. E-mail: lewis@physast.uga.edu

    2014-07-20

    Using classical molecular dynamics, we have simulated the sticking and scattering process of a hydrogen atom on an amorphous ice film to predict the sticking probability of hydrogen on ice surfaces. A wide range of initial kinetic energies of the incident hydrogen atom (10 K-600 K) and two different ice temperatures (10 K and 70 K) were used to investigate this fundamental process in interstellar chemistry. We report here the sticking probability of atomic hydrogen as a function of incident kinetic energy, gas temperature, and substrate temperature, which can be used in astrophysical models. The current results are compared to previous theoretical and experimental studies that have reported a wide range in the sticking coefficient.

  12. Solar Grade Silicon from Agricultural By-products

    SciTech Connect (OSTI)

    Richard M. Laine

    2012-08-20

    starts one step upstream from all other Sipv production efforts. Our process starts by producing high purity SiO2/C feedstocks from which Sipv can be produced in a single, chlorine free, final EAF step. Specifically, our unique technology, and the resultant SiO2/C product can serve as high purity feedstocks to existing metallurgical silicon (Simet) producers, allowing them to generate Sipv with existing US manufacturing infrastructure, reducing the overall capital and commissioning schedule. Our low energy, low CAPEX and OPEX process purifies the silica and carbon present in rice hull ash (RHA) at low temperatures (< 200C) to produce high purity (5-6 Ns) feedstock for production of Sipv using furnaces similar to those used to produce Simet. During the course of this project we partnered with Wadham Energy LP (Wadham), who burns 220k ton of rice hulls (RH)/yr generating 200 GWh of electricity/yr and >30k ton/yr RHA. The power generation step produces much more energy (42 kWh/kg of final silicon produced) than required to purify the RHA (5 kWh/kg of Sipv, compared to 65 kWh/kg noted above. Biogenic silica offers three very important foundations for producing high purity silicon. First, wastes from silica accumulating plants, such as rice, corn, many grasses, algae and grains, contain very reactive, amorphous silica from which impurities are easily removed. Second, plants take up only a limited set of, and minimal quantities of the heavy metals present in nature, meaning fewer minerals must be removed. Third, biomass combustion generates a product with intrinsic residual carbon, mixed at nanometer length scales with the SiO2. RHA is 80-90 wt% high surface area (20 m2/g), amorphous SiO2 with some simple mineral content mixed intimately with 5-15 wt% carbon. The mineral content is easily removed by low cost, acid washes using Mayaterials IP, leading to purified rice hull ash (RHAclean) at up to 6N purity. This highly reactive silica is partially extracted from RHAclean at 200

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