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1

Growth of hydrogenated amorphous silicon (a-Si:H) on patterned substrates for increased mechanical stability  

DOE Green Energy (OSTI)

Residual stress in hydrogenated amorphous silicon (a-Si:H) film, which causes substrate bending and delamination, is studied. The internal stress can be reduced by controlling deposition parameters, but it is known to produce a trade-off between stress and electronic quality. Selective area deposition, in which the deposition area is reduced by making islands, reduced the stress when the lateral dimension of the islands becomes comparable to the film thickness. The overall stress is reduced by approximately 40% when the lateral dimension is decreased to 40 {mu}m, but the adhesion was not improved much. However, substrates having a 2-dimensional array of inversed pyramids of 200 {mu}m in lateral dimension produced overall stress 3 {approximately} 4 times lower than that on the normal substrates. Such substrates were prepared by anisotropic etching of silicon wafers. The inversed pyramid structure also has other advantages including minimized delamination and increased effective thickness. Computer simulation confirmed that the overall stress can be reduced by deposition on the pyramidal structure.

Hong, W.S.; Nieto, J.C.D.; Ruiz, O.; Perez-Mendez, V.

1994-12-01T23:59:59.000Z

2

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

SciTech Connect

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.

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

2011-10-04T23:59:59.000Z

3

Amorphous silicon radiation detectors  

DOE Patents (OSTI)

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.

Street, Robert A. (Palo Alto, CA); Perez-Mendez, Victor (Berkeley, CA); Kaplan, Selig N. (El Cerrito, CA)

1992-01-01T23:59:59.000Z

4

Amorphous silicon radiation detectors  

DOE Patents (OSTI)

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.

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

1992-11-17T23:59:59.000Z

5

Compensated amorphous silicon solar cell  

DOE Patents (OSTI)

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.

Carlson, David E. (Yardley, PA)

1980-01-01T23:59:59.000Z

6

Compensated amorphous silicon solar cell  

SciTech Connect

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.

Devaud, Genevieve (629 S. Humphrey Ave., Oak Park, IL 60304)

1983-01-01T23:59:59.000Z

7

Three dimensional amorphous silicon/microcrystalline silicon solar cells  

DOE Patents (OSTI)

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.

Kaschmitter, J.L.

1996-07-23T23:59:59.000Z

8

Three dimensional amorphous silicon/microcrystalline silicon solar cells  

DOE Patents (OSTI)

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.

Kaschmitter, James L. (Pleasanton, CA)

1996-01-01T23:59:59.000Z

9

Amorphous and Microcrystalline Silicon Solar Cells: Preprint  

DOE Green Energy (OSTI)

We review the progress made by amorphous silicon solar cells, including the emerging technology of solar cells of microcrystalline silicon. The long-term trend in the efficiency of stabilized laboratory cells based on a-Si:H has been a rise of {approx}0.6 % per year. The recent trend in the a-Si,Ge:H cell efficiency alone, measured in the spectral window assigned to the bottom device in a triple-junction cell, has been an increase of {approx}0.16% per year. These improvements have brought within reach the target of 15% efficiency identified by EPRI and DOE for widespread application. Our review leads to an identification of areas of promising research, with emphasis on the fundamental science required to reach the 15% target, and then to move to the next-level efficiency goal.

Wagner, S. (Princeton University); Carlson, D. E. (Solarex); Branz, H. M. (National Renewable Energy Laboratory)

1999-04-01T23:59:59.000Z

10

Amorphous silicon solar cells  

SciTech Connect

The fabrication, performance, and applications of a-Si solar cells are discussed, summarizing the results of recent experimental investigations and trial installations. Topics examined include the fundamental principles and design strategies of solar power installations; the characteristics of monocrystalline-Si solar cells; techniques for reducing the cost of solar cells; independent, linked, and hybrid solar power systems; proposed satellite solar power systems; and the use of solar cells in consumer appliances. Consideration is given to the history of a-Si, a-Si fabrication techniques, quality criteria for a-Si films, solar cells based on a-Si, and techniques for increasing the efficiency and lowering the cost of a-Si solar cells. Graphs, diagrams, drawings, and black-and-white and color photographs are provided. 136 references.

Takahashi, K.; Konagai, M.

1986-01-01T23:59:59.000Z

11

Cermet layer for amorphous silicon solar cells  

DOE Patents (OSTI)

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.

Hanak, Joseph J. (Lawrenceville, NJ)

1979-01-01T23:59:59.000Z

12

Tandem junction amorphous silicon solar cells  

DOE Patents (OSTI)

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.

Hanak, Joseph J. (Lawrenceville, NJ)

1981-01-01T23:59:59.000Z

13

Hydrogenated amorphous silicon-germanium alloys  

SciTech Connect

This report describes the effects of the germanium fraction in hydrogenated amorphous silicon-germanium alloys on various parameters, especially those that are indicators of film quality, and the impact of deposition methods, feedgas mixtures, and other deposition parameters on a SiGe:H and a-SiGe:H:F film characteristics and quality. Literature data show the relationship between germanium content, hydrogen content, deposition method (various glow discharges and CVD), feedgas lmixture, and other parameters and properties, such as optical band gap, dark and photoconductivities, photosensitivity, activation energy, Urbach parameter, and spin density. Some of these are convenient quality indicators; another is the absence of microstructure. Examining RF glow discharge with both a diode and triode geometry, DC proximity glow discharge, microwave glow discharge, and photo-CVD, using gas mixtures such as hydrogen-diluted and undiluted mixtures of silane/germane, disilane/germane, silane/germaniumtetrafluoride, and others, it was observed that hydrogen dilution (or inert gas dilution) is essential in achieving high photosensitivity in silicon-germanium alloys (in contradistinction to amorphous hydrogenated silicon). Hydrogen dilution results in a higher photosensitivity than do undiluted gas mixtures. 81 refs., 42 figs., 7 tabs.

Luft, W.

1988-02-01T23:59:59.000Z

14

High resolution amorphous silicon radiation detectors  

DOE Patents (OSTI)

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.

Street, Robert A. (Palo Alto, CA); Kaplan, Selig N. (El Cerrito, CA); Perez-Mendez, Victor (Berkeley, CA)

1992-01-01T23:59:59.000Z

15

High resolution amorphous silicon radiation detectors  

DOE Patents (OSTI)

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.

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

1992-05-26T23:59:59.000Z

16

Hydrogenated amorphous silicon photonics.  

E-Print Network (OSTI)

??Silicon Photonics is quickly proving to be a suitable interconnect technology for meeting the future goals of on-chip bandwidth and low power requirements. However, it (more)

Narayanan, Karthik

2011-01-01T23:59:59.000Z

17

Amorphous Silicon Based Neutron Detector  

SciTech Connect

Various large-scale neutron sources already build or to be constructed, are important for materials research and life science research. For all these neutron sources, neutron detectors are very important aspect. However, there is a lack of a high-performance and low-cost neutron beam monitor that provides time and temporal resolution. The objective of this SBIR Phase I research, collaboratively performed by Midwest Optoelectronics, LLC (MWOE), the University of Toledo (UT) and Oak Ridge National Laboratory (ORNL), is to demonstrate the feasibility for amorphous silicon based neutron beam monitors that are pixilated, reliable, durable, fully packaged, and fabricated with high yield using low-cost method. During the Phase I effort, work as been focused in the following areas: 1) Deposition of high quality, low-defect-density, low-stress a-Si films using very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) at high deposition rate and with low device shunting; 2) Fabrication of Si/SiO2/metal/p/i/n/metal/n/i/p/metal/SiO2/ device for the detection of alpha particles which are daughter particles of neutrons through appropriate nuclear reactions; and 3) Testing of various devices fabricated for alpha and neutron detection; As the main results: High quality, low-defect-density, low-stress a-Si films have been successfully deposited using VHF PECVD on various low-cost substrates; Various single-junction and double junction detector devices have been fabricated; The detector devices fabricated have been systematically tested and analyzed. Some of the fabricated devices are found to successfully detect alpha particles. Further research is required to bring this Phase I work beyond the feasibility demonstration toward the final prototype devices. The success of this project will lead to a high-performance, low-cost, X-Y pixilated neutron beam monitor that could be used in all of the neutron facilities worldwide. In addition, the technologies developed here could be used to develop X-ray and neutron monitors that could be used in the future for security checks at the airports and other critical facilities. The project would lead to devices that could significantly enhance the performance of multi-billion dollar neutron source facilities in the US and bring our nation to the forefront of neutron beam sciences and technologies which have enormous impact to materials, life science and military research and applications.

Xu, Liwei

2004-12-12T23:59:59.000Z

18

Amorphous silicon solar cell allowing infrared transmission  

DOE Patents (OSTI)

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.

Carlson, David E. (Yardley, PA)

1979-01-01T23:59:59.000Z

19

Stable Hydrogenated Amorphous Silicon Germanium for Photovoltaic Applications. Experimental and Computational Studies.  

E-Print Network (OSTI)

??The research was aimed at the optimisation of low band gap amorphous silicon germanium (a-SiGe:H) materials with special emphasis on developing a highly absorbing material (more)

Jimnez Zambrano, R.

2003-01-01T23:59:59.000Z

20

The future of amorphous silicon photovoltaic technology  

DOE Green Energy (OSTI)

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.

Crandall, R.; Luft, W.

1995-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Compensated amorphous-silicon solar cell  

DOE Patents (OSTI)

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.

Devaud, G.

1982-06-21T23:59:59.000Z

22

Progress in amorphous silicon PV technology: An update  

DOE Green Energy (OSTI)

To reach the 15% stabilized efficiency goal for amorphous silicon (a-Si) modules by the year 2005, the National Renewable Energy Laboratory has established four research teams. The teams -- with members from industry, universities, and NREL -- have been in operation for 2.5 years now. Consensus has been reached that a triple-junction a-Si structure is needed to reach the efficiency goal. Performance parameter goals for the overall structure and the three component cells have been formulated. All four teams have generated their own development plans. Individual team progress relative to the plans is reported.

Luft, W.; Branz, H.M. [National Renewable Energy Lab., Golden, CO (United States); Dalal, V.L. [Iowa State Univ., Ames, IA (United States); Hegedus, S.S. [Delaware Univ., Newark, DE (United States). Inst. of Energy Conversion; Schiff, E.A. [Syracuse Univ., NY (United States)

1995-07-01T23:59:59.000Z

23

Deposition of device quality low H content, amorphous silicon films  

DOE Patents (OSTI)

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.

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

1995-03-14T23:59:59.000Z

24

Innovative Characterization of Amorphous and Thin-Film Silicon for Improved Module Performance: 1 February 2005 - 31 July 2008  

DOE Green Energy (OSTI)

Electron spin resonance and nuclear magnetic resonance was done on amorphous silicon samples (modules with a-Si:H and a-SixGe1-x:H intrinsic layer) to study defects that contribute to Staebler-Wronski effect.

Taylor, P. C.; Williams, G. A.

2009-09-01T23:59:59.000Z

25

Amorphous-silicon thin-film heterojunction solar cells  

DOE Green Energy (OSTI)

The investigation of amorphous silicon materials at MTSEC has had two major thrusts: (1) to improve the amorphous material, i.e., obtain a low state density in the gap, improve the carrier collection depth and diminish non-radiative recombinations; and (2) to attempt to understand and improve on the limitations of the junction devices while evaluating the amorphous silicon materials. In the first of these efforts, the investigation has continued to examine the modifications to the a-Si(H) network by alloying silicon with other group IVA elements, either in binary or ternary compositions, and/or by replacing the hydrogenation for defect compensation with a combination of hydrogenation and alkylation or hydrogenation and halogenation. The doped junction layers are being examined in an attempt to determine the limiting characteristics of the junctions in solar cell devices of these amorphous materials. Amorphous alloys of Si-Ge, Si-C, Si-Sn were prepared as well as ternary compositions of Si-Ge-C and Si-Sn-C. In addition, Na vapor was added to the gas feed to deposit a-Si(Na, H) films, and to prepare Si-Sn, fluoride was added along with the tin by vapor additions of SnF/sub 4/ to the gas feed. The optical properties of these materials were measured, and structural and compositional information was obtained from the IR vibrational spectra using the scanning electron microscope and from analyses using scanning Auger microscopy. Electrical measurements have included the dark conductivity and the photo conductivity under room fluorescent light and at AM1 conditions. With alloys that displayed promising photoconductive properties n-i-p devices were prepared to assess the solar cell properties. Details are presented. (WHK)

Cretella, M. C.; Gregory, J. A.; Sandstrom, D. B.; Paul, W.

1981-01-01T23:59:59.000Z

26

Inverted amorphous silicon solar cell utilizing cermet layers  

DOE Patents (OSTI)

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.

Hanak, Joseph J. (Lawrenceville, NJ)

1979-01-01T23:59:59.000Z

27

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

DOE Patents (OSTI)

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.

Carlson, David E. (Yardley, PA)

1982-01-01T23:59:59.000Z

28

Metal electrode for amorphous silicon solar cells  

DOE Patents (OSTI)

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.

Williams, Richard (Princeton, NJ)

1983-01-01T23:59:59.000Z

29

Observation of enhanced infrared photoresponse in forward?biased amorphous silicon p?i?n diodes  

Science Conference Proceedings (OSTI)

The photoconductive response of hydrogenated amorphous silicon (a?Si:H) p?i?n diodes has been investigated under conditions of low?temperature operation. We show that cooled p?i?n diodes exhibit an enhanced infrared response when operated under forward bias conditions. The induced IR response is of the order of 10?3A/W

J. Wind; G. Mller

1991-01-01T23:59:59.000Z

30

High Efficiency and High Rate Deposited Amorphous Silicon-Based Solar Cells  

E-Print Network (OSTI)

of a triple cell showing 10.7% stable efficiency. Figure 4-1 Schematic diagram of the Hot Wire CVD deposition. Task 7: High-rate deposition of a-Si based solar cells We have conducted extensive research using a hot1 High Efficiency and High Rate Deposited Amorphous Silicon-Based Solar Cells PHASE I Annual

Deng, Xunming

31

SIMS Study of Elemental Diffusion During Solid Phase Crystallization of Amorphous Silicon  

DOE Green Energy (OSTI)

Crystallization of hydrogenated amorphous silicon (a-Si:H) films deposited on low-cost substrates shows potential for solar cell applications. Secondary ion mass spectrometry (SIMS) was used to study impurity incorporation, hydrogen evolution, and dopant diffusion during the crystallization process

Reedy, R. C.; Young, D.; Branz, H. M.; Wang, Q.

2005-11-01T23:59:59.000Z

32

Chemical vapor deposition of hydrogenated amorphous silicon from disilane  

SciTech Connect

The authors describe hydrogenated amorphous silicon (a-Si:H) thin films deposited at growth rates of 1 to 30 A/s by chemical vapor deposition (CVD) from disilane source gas at 24 torr total pressure in a tubular reactor. The effects of substrate temperature and gas holding time (flow rate) on film growth rate and effluent gas composition were measured at temperatures ranging from 360{sup 0} to 485{sup 0}C and gas holding times from 3 to 62s. Effluent gases determined by gas chromatography included silane, disilane and other higher order silanes. A chemical reaction engineering model, based on a silylene (SiH/sub 2/) insertion gas phase reaction network and film growth from both SiH/sub 2/ and high molecular weight silicon species, Si/sub n/H/sub 2n/, was developed. The model predictions were in good agreement with experimentally determined growth rates and effluent gas compositions.

Bogaert, R.J.; Russell, T.W.F.; Klein, M.T. (Delaware Univ., Newark, DE (USA). Dept. of Chemical Engineering); Rocheleau, R.E.; Baron, B.N. (Delaware Univ., Newark, DE (USA). Inst. of Energy Conversion)

1989-10-01T23:59:59.000Z

33

Amorphous silicon/polycrystalline thin film solar cells  

DOE Patents (OSTI)

An improved photovoltaic solar cell is described including a p-type amorphous silicon layer, intrinsic amorphous silicon, and an n-type polycrystalline semiconductor such as cadmium sulfide, cadmium zinc sulfide, zinc selenide, gallium phosphide, and gallium nitride. The polycrystalline semiconductor has an energy bandgap greater than that of the amorphous silicon. The solar cell can be provided as a single-junction device or a multijunction device.

Ullal, H.S.

1991-03-13T23:59:59.000Z

34

NMR Studies of Molecular Hydrogen in Hydrogenated Amorphous Silicon  

DOE Green Energy (OSTI)

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.

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

2000-01-01T23:59:59.000Z

35

Improved Amorphous Silicon Solar Cells - Energy Innovation Portal  

Alex Zettl, Jeffrey Grossman and Lucas Wagner of Lawrence Berkeley National Laboratory have invented hydrogenated amorphous silicon solar cells with 30% improved ...

36

Crystallization and doping of amorphous silicon on low temperature plastic  

DOE Patents (OSTI)

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.

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

1994-09-13T23:59:59.000Z

37

Crystallization and doping of amorphous silicon on low temperature plastic  

DOE Patents (OSTI)

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.

Kaschmitter, James L. (Pleasanton, CA); Truher, Joel B. (Palo Alto, CA); Weiner, Kurt H. (Campbell, CA); Sigmon, Thomas W. (Beaverton, OR)

1994-01-01T23:59:59.000Z

38

Monolithic amorphous silicon modules on continuous polymer substrate  

DOE Green Energy (OSTI)

This report examines manufacturing monolithic amorphous silicon modules on a continuous polymer substrate. Module production costs can be reduced by increasing module performance, expanding production, and improving and modifying production processes. Material costs can be reduced by developing processes that use a 1-mil polyimide substrate and multilayers of low-cost material for the front encapsulant. Research to speed up a-Si and ZnO deposition rates is needed to improve throughputs. To keep throughput rates compatible with depositions, multibeam fiber optic delivery systems for laser scribing can be used. However, mechanical scribing systems promise even higher throughputs. Tandem cells and production experience can increase device efficiency and stability. Two alternative manufacturing processes are described: (1) wet etching and sheet handling and (2) wet etching and roll-to-roll fabrication.

Grimmer, D.P. (Iowa Thin Film Technologies, Inc., Ames, IA (United States))

1992-03-01T23:59:59.000Z

39

Research on stable, high-efficiency amorphous silicon multijunction modules  

DOE Green Energy (OSTI)

This report describes research on semiconductor and non-semiconductor materials to enhance the performance of multi-band-gap, multijunction panel with an area greater than 900 cm[sup 2] by 1992. Double-junction and triple-junction cells are mode on a Ag/ZnO back reflector deposited on stainless steel substrates. An a-SiGe alloy is used for the i-layer in the bottom and the middle cells; the top cell uses an amorphous silicon alloy. After the evaporation of an 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 1-ft[sup 2] monolithic module.

Guha, S. (United Solar Systems Corp., Troy, MI (United States))

1992-09-01T23:59:59.000Z

40

Superlattice doped layers for amorphous silicon photovoltaic cells  

DOE Patents (OSTI)

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.

Arya, Rajeewa R. (Doylestown, PA)

1988-01-12T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Recombination and metastability in amorphous silicon and silicon germanium alloys  

DOE Green Energy (OSTI)

This report describes the first year of a continuing research study to understand how recombination, trapping, and band-mobility modification affecting the electronic properties of amorphous semiconductors can be measured, characterized, and described by an appropriate spectrum of defect states, and how light-induced defects in a-Si:H and native defects in a-SiGe:H affect transport properties in these materials. The objective was to determine how the Staebler-Wronski defects affect the electronic processes in a-Si:H and a-SiGe:H films. To do this, electroluminescence (EL) and forward bias current in p-i-n devices (i-layer thickness > 2 {mu}m) were studied both experimentally and theoretically before and after light soaking. A simple picture was developed to compare forward bias current to the EL signal. The result was unexpected: the product of the final current times the rise time was not constant before and after light soaking as expected from the concept of gain band width, but instead changed radically. The rise time t{sub x} increased by more than one order of magnitude while the final current I{sub f} did not change significantly with light soaking. On the other hand the I{sub f}t{sub x} product did hold close to a constant when only the applied voltage changed.

Silver, M. (North Carolina Univ., Chapel Hill, NC (United States))

1992-07-01T23:59:59.000Z

42

Hydrogenated amorphous silicon produced by pyrolysis and photolysis of disilane  

SciTech Connect

A new class of hydrogenated amorphous silicon (a-Si:H) was prepared by the thermal CVD and photo-CVD of disilane. In the low pressure thermal CVD, the horizontal quartz tube heated by resistance heaters was used as a reactor. The growth rate of the thermal CVD a-Si:H films is plotted as a function of reciprocal substrate temperature. As a new alternative approach to prepare high quality CVD films at temperatures below 300/sup 0/C, the direct photochemical decomposition of disilane has been attempted utilizing a low pressure mercury lamp as a UV radiation source. In the case of undoped and phosphorus doped films, the growth rate is independent of the substrate temperature. In contrast to this, for boron doping, the growth rate has an activation energy of 0.64 eV as in the case of the thermal CVD although the growth rate of the photo-CVD is about three times as large as that of the thermal CVD. This implies that the photoCVD process in boron doping is dominated by the thermal reaction catalyzed with diborane. The dark conductivity and photoconductivity before and after light exposure (AM-1, 200 mW/cm/sup 2/) exhibit no change, indicating the absence of the light-soak degradation in photo-CVD films. The valency control in thermal CVD and photo-CVD is also successfully carried out.

Ashida, Y.; Hirose, M.; Isogaya, K.; Kitagawa, N.; Mishima, Y.; Osuka, Y.

1984-05-01T23:59:59.000Z

43

Method of inducing differential etch rates in glow discharge produced amorphous silicon  

DOE Patents (OSTI)

A method of inducing differential etch rates in glow discharge produced amorphous silicon by heating a portion of the glow discharge produced amorphous silicon to a temperature of about 365.degree. C. higher than the deposition temperature prior to etching. The etch rate of the exposed amorphous silicon is less than the unheated amorphous silicon.

Staebler, David L. (Lawrenceville, NJ); Zanzucchi, Peter J. (Lawrenceville, NJ)

1980-01-01T23:59:59.000Z

44

High-rate deposition of hydrogenated amorphous silicon films and devices  

DOE Green Energy (OSTI)

This report summarizes the status of high-rate deposition technologies associated with amorphous silicon thin films for photovoltaic applications. The report lists (1) deposition rates for a-Si:H films according to source and method and (2) efficiencies and other parameters of a-Si:H solar cells. Two main deposition source materials, silane and disilane, are discussed, as well as effects of boron doping. The effects of various deposition parameters on film characteristics and on deposition rate are presented, as well as the effects of annealing on high-deposition-rate films. Light-induced effects are also discussed. Finally, progress and problems in this field of study are summarized.

Luft, W.

1987-04-01T23:59:59.000Z

45

Improved performance of amorphous silicon solar cells via scattering from surface plasmon polaritons in nearby metallic nanoparticles  

E-Print Network (OSTI)

s to remove the surface oxide. A 20 nm indium tin oxide ITO contact layer was then depos- ited by rf.S. National Renewable Energy Laboratory for providing a-Si:H thin films for this work. 1 A. Luque and S An engineered enhancement in short-circuit current density and energy conversion efficiency in amorphous silicon

Yu, Edward T.

46

Role of Amorphous Silicon and Tunneling in Heterojunction with Intrinsic Thin Layer (HIT) Solar Cells  

Science Conference Proceedings (OSTI)

This work analyzes heterojunction with intrinsic thin layer (HIT) solar cells using numerical simulations. The differences between the device physics of cells with p- and n-type crystalline silicon (c-Si) wafers are substantial. HIT solar cells with n-type wafers essentially form a n/p/n structure, where tunneling across the junction heterointerfaces is a critical transport mechanism required to attain performance exceeding 20%. For HIT cells with p-type wafers, only tunneling at the back-contact barrier may be important. For p-wafer cells, the hydrogenated amorphous silicon (a-Si:H) between the indium tin oxide (ITO) and crystalline silicon may act as a passivating buffer layer but, otherwise, does not significantly contribute to device performance. For n-wafer cells, the carrier concentration and band alignment of this a-Si:H layer are critical to device performance.

Kanevce, A.; Metzger, W. K.

2009-05-01T23:59:59.000Z

47

Hydrogenated amorphous silicon films prepared by glow discharge of disilane  

DOE Green Energy (OSTI)

This report describes the results of an investigation of the properties of hydrogenated amorphous silicon films and the efficiency of amorphous silicon solar cells deposited from disilane at rates of 1.5 nanometers/second or greater. The study was divided into two parts, investigation of basic materials properties of hydrogenated amorphous silicon thin films and the fabrication of glass-P-I-N-metal solar cells. The thin film materials properties investigated included the dark conductivity, photoconductivity, dihydride/monohydride concentration ratio, activation energy, and mobility-lifetime product. Hydrogenated amorphous silicon solar cells were fabricated with an intrinsic layer which was deposited at 1.5 nanometers/second. The absolute and reverse bias quantum yields were measured and solar cell efficiencies of 5% were achieved. Attempts to increase the efficiency by reverse bias annealing are also reported. 7 refs., 27 figs.

Wiesmann, H.J. (UHT Corp., Dobbs Ferry, NY (USA))

1990-01-01T23:59:59.000Z

48

Characterization of Amorphous Silicon Thin Films and PV Devices: Final Technical Report, January 1998 - October 2001  

DOE Green Energy (OSTI)

This report describes the most significant results of the three phases: (1) development of a second harmonic detection technique for electron spin resonance (ESR) and optically excited ESR (LESR) in a-Si:H and related alloys, (2) discovery of universal kinetics for the decay of optically excited electrons and holes in a-Si:H and related alloys at low temperatures, (3) first detection of optically excited band-tail electrons and holes in hydrogenated amorphous germanium (a-Ge:H), (4) first ESR study of the kinetics for the production of silicon dangling bonds in a-Si:H at low temperatures, and (5) determination from 1H NMR that there exists an order of magnitude more molecular hydrogen (H2) in a-Si:H than previously measured.

Taylor, P. C.

2002-03-01T23:59:59.000Z

49

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

DOE Green Energy (OSTI)

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.

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

2006-05-01T23:59:59.000Z

50

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

SciTech Connect

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.

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

2009-06-08T23:59:59.000Z

51

Tritiated Amorphous Silicon: Insights into the Staebler-Wronski Mechanism  

DOE Green Energy (OSTI)

Hydrogen, though essential for device-quality amorphous silicon, likely contributes to the light-induced degradation process (Staebler-Wronski effect) that reduces the solar cell efficiency by about 4 absolute percent. We are testing the role of hydrogen by using its isotope tritium. When tritium bonded to Si spontaneously decays into inert helium-3, it should leave behind the Si dangling bond defect. We have studied degradation due to tritium and note its resemblance to the Staebler-Wronski effect. Surprisingly, 100x fewer defects are created than expected from the tritium decay rate, suggesting a mechanism that heals most of the defects, even at temperatures down to 4 K. We consider different mechanisms for the thermal and athermal healing processes (e.g. motion of hydrogen, effect of beta-electrons, decay of hydrogen-tritium molecules). Our findings shed new light on the degradation mechanism in a Si:H and help reveal the role of hydrogen and structural rearrangements near a newly created defect.

Stradins, P.; Branz, H. M.; Whitaker, J.; Viner, J.; Taylor, P. C.; Johnson, E.; Kherani, N.; Zukotynski, S.

2005-01-01T23:59:59.000Z

52

Amorphous silicon pixel radiation detectors and associated thin film transistor electronics readout  

SciTech Connect

We describe the characteristics of thin (1 {mu}m) and thick (> 30 {mu}m) hydrogenated amorphous silicon p-i-n diodes which are optimized for detecting and recording the spatial distribution of charged particles, x-ray, {gamma} rays and thermal neutrons. For x-ray, {gamma} ray, and charged particle detection we can use thin p-i-n photosensitive diode arrays coupled to evaporated layers of suitable scintillators. For thermal neutron detection we use thin (2{approximately}5 {mu}m) gadolinium converters on 30 {mu}m thick a-Si:H diodes. For direct detection of minimum ionizing particles and others with high resistance to radiation damage, we use the thick p-i-n diode arrays. Diode and amorphous silicon readouts as well as polysilicon pixel amplifiers are described.

Perez-Mendez, V.; Cho, G.; Drewery, J.; Jing, T.; Kaplan, S.N.; Mireshghi, A.; Wildermuth, D. (Lawrence Berkeley Lab., CA (United States)); Goodman, C. (Air Techniques Corp., Hicksville, New York (United States)); Fujieda, I. (NEC Corp., Tokyo (Japan))

1992-07-01T23:59:59.000Z

53

Solid-phase epitaxy of silicon amorphized by implantation of the alkali elements rubidium and cesium  

Science Conference Proceedings (OSTI)

The redistribution of implanted Rb and Cs profiles in amorphous silicon during solid-phase epitaxial recrystallization has been investigated by Rutherford backscattering spectroscopy and secondary ion mass spectroscopy. For the implantation dose used in these experiments, the alkali atoms segregate at the a-Si/c-Si interface during annealing resulting in concentration peaks near the interface. In this way, the alkali atoms are moved towards the surface. Rutherford backscattering spectroscopy in ion channeling configuration was performed to measure average recrystallization rates of the amorphous silicon layers. Preliminary studies on the influence of the alkali atoms on the solid-phase epitaxial regrowth rate reveal a strong retardation compared to the intrinsic recrystallization rate.

Maier, R.; Haeublein, V.; Ryssel, H.; Voellm, H.; Feili, D.; Seidel, H.; Frey, L. [Lehrstuhl fuer Elektronische Bauelemente (LEB), Universitaet Erlangen-Nuernberg, Cauerstrasse 6, 91058 Erlangen (Germany); Fraunhofer-Institut fuer Integrierte Systeme und Bauelementetechnologie (IISB), Schottkystrasse 10, 91058 Erlangen (Germany); Lehrstuhl fuer Elektronische Bauelemente (LEB), Universitaet Erlangen-Nuernberg, Cauerstrasse 6, 91058 Erlangen (Germany) and Fraunhofer-Institut fuer Integrierte Systeme und Bauelementetechnologie (IISB), Schottkystrasse 10, 9 (Germany); Lehrstuhl fuer Mikromechanik, Mikrofluidik/ Mikroaktorik (LMM), Universitaet des Saarlandes, Campus A5.1, 66123 Saarbruecken (Germany); Lehrstuhl fuer Elektronische Bauelemente (LEB), Universitaet Erlangen-Nuernberg, Cauerstrasse 6, 91058 Erlangen (Germany) and Fraunhofer-Institut fuer Integrierte Systeme und Bauelementetechnologie (IISB), Schottkystrasse 10,91 (Germany)

2012-11-06T23:59:59.000Z

54

Hydrogenated amorphous silicon films produced by chemical vapor deposition: Final report  

SciTech Connect

Hydrogenated amorphous silicon (a-Si:H) is a technologically important semiconductor, well-suited for solar photovoltaic energy conversion and thin film device applications. While the glow discharge technique is widely used for the deposition of a-Si:H films, this work is focused on the use of the chemical vapor deposition (CVD) technique, i.e., the thermal decomposition of disilane and higher silanes, for the deposition of a-Si:H films. A simple technique for the preparation of disilane and higher silanes by using an electric discharge in monosilane under atmospheric pressure has been developed, and the discharge product can be used directly for the deposition process. The important parameters of the CVD process including the substrate temperature, the composition and flow rate of the reaction mixture, and the nature of the diluent gas for disilane, have also been investigated. The deposition rate of a-Si:H films in a helium atmosphere is considerably higher than that in a hydrogen atmosphere, and the CVD process in a helium atmosphere is well-suited for the deposition of thick a-Si:H films. The a-Si:H films deposited under various conditions have been characterized by the photoconductivity, dissolution rate, optical absorption, mechanical stress, gap state density, minority carrier diffusion length, and stability measurements. On the basis of these measurements, a-Si:H films deposited by the thermal decomposition of disilane in a helium atmosphere exhibit better structural and electronic properties than those deposited in a hydrogen atmosphere.

Not Available

1987-04-01T23:59:59.000Z

55

High deposition rate preparation of amorphous silicon solar cells by rf glow discharge decomposition of disilane  

SciTech Connect

The optical and electrical properties of hydrogenated amorphous silicon films produced by rf glow discharge decomposition of disilane diluted in helium (Si/sub 2/H/sub 6//He = 1/9) have been studied while systematically varying the film deposition rate. The properties and composition of the films were monitored by measuring the optical band gap, IR vibrational spectrum, dark conductivity, and the photoconductivity as a function of the deposition rate. The photoluminescence of the high deposition rate films gave a peak at 1.33 eV. These films, whose properties are rather similar to those of the conventional a-Si:H films prepared from monosilane, have been used to fabricate nip-type a-Si:H solar cells. At a deposition rate of 11 A/sec, a conversion efficiency of 6.86% was obtained. This high efficiency shows that disilane is applicable for mass production fabrication of a-Si:H solar cells.

Kenne, J.; Ohashi, Y.; Matsushita, T.; Konagai, M.; Takahashi, K.

1984-01-15T23:59:59.000Z

56

Performance and Modeling of Amorphous Silicon Photovoltaics for Building-Integrated Applications (Preprint prepared for Solar 99)  

Science Conference Proceedings (OSTI)

Amorphous silicon photovoltaic (PV) modules offer several advantages for building-integrated applications. The material can be deposited on glass or flexible substrates, which allows for products like roofing shingles and integrated PV/building glass. The material also has a uniform surface, which is ideal for many architectural applications. Amorphous silicon modules perform well in warm weather and have a small temperature coefficient for power. Depending on the building load, this may be beneficial when compared to crystalline systems. At the National Renewable Energy Laboratory, we are monitoring the performance of a triple-junction a-Si system. The system consists of 72 roofing shingles mounted directly to simulated roofing structures. This paper examines the performance of the building-integrated amorphous silicon PV system and applicability for covering residential loads. A simple model of system performance is also developed and is presented.

Kroposki, B.; Hansen, R.

1998-06-07T23:59:59.000Z

57

Amorphous silicon research: Phase II. Annual technical progress report, August 1, 1995--July 31, 1996  

DOE Green Energy (OSTI)

This report describes the research performed during Phase II of a three-phase, three-year program under NREL Subcontract No. ZAN-4-13318-02. The research program is intended to expand, enhance and accelerate knowledge and capabilities for the development of high-performance, two-terminal multijunction hydrogenated amorphous silicon (a-Si:H) alloy modules. It is now well recognized that a multifunction, multibandgap approach has the potential of achieving the highest stable efficiency in a-Si:H alloy solar cells. In this approach, the bandgap of the materials of the component cell is varied in order to capture a wide spectrum of the solar photons. Significant progress has been made in the development of materials and cell design in the last few years, and a stable module efficiency of 10.2% has been demonstrated over one-square-foot area using a triple-junction approach in which the bottom two component cells use hydrogenated amorphous silicon-germanium (a-SiGe:H) alloy. In order to meet the Department of Energy goal of achievement of 12% stable module efficiency, it is necessary to make further improvements in each of the component cells. This has been the thrust of the current program.

Guha, S. [United Solar Systems Corp., Troy, MI (United States)

1996-10-01T23:59:59.000Z

58

Transmissive metallic contact for amorphous silicon solar cells  

DOE Patents (OSTI)

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.

Madan, A.

1984-11-29T23:59:59.000Z

59

Performance of amorphous silicon photovoltaic systems, 1985--1989  

DOE Green Energy (OSTI)

This report discusses the performance of commercial amorphous silicon modules used in photovoltaic power systems from 1985 through 1989. Topics discussed include initial degradation, reliability, durability, and effects of temperature and solar irradiance on peak power and energy production. 6 refs., 18 figs.

Not Available

1990-04-01T23:59:59.000Z

60

Thin-film amorphous silicon alloy research partnership, Phase I. Annual technical progress report, February 2, 1995--February 1, 1996  

DOE Green Energy (OSTI)

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 multifunction amorphous silicon (a-Si) alloy modules. The near-term goal of the program is to achieve 12% stable module efficiency by 1998 using the multifunction approach. This report describes research on back reflectors of Ag/TiO{sub 2}/ZnO.

Guha, S. [United Solar Systems Corp., Troy, MI (United States)

1996-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Plasma-assisted CVD of fluorinated, hydrogenated amorphous silicon. Final report  

DOE Green Energy (OSTI)

During the past year, three novel large-area (100 cm/sup 2/) a-Si:H solar cells were developed with the following configurations: inverted NIP/SS cells with an improved red response; inverted a-Si:H/a-B:H heterojunction cells with high V/sub oc/; and NIP/metal cells with a CVD P-layer grown pyrolytically from silane and diborane. Initial experiments were performed using disilane as the deposition gas for the intrinsic layer in both NIP/SS and PIN/SS structures. Coatings of In/sub 2/O/sub 3/, using a technique developed by Dr. Ovadyahu, were applied to NIP/SS cells in order to evaluate its potential as a conductive coating in practical amorphous silicon solar cells.

Coleman, J.H.; Hammes, J.P.; Wiesmann, H.J.

1981-01-01T23:59:59.000Z

62

Photocharge transport and recombination measurements in amorphous silicon films and solar cells by photoconductive frequency mixing. Annual subcontract report, May 13, 1994--May 12, 1995  

DOE Green Energy (OSTI)

The continuous decay of electron drift mobility in intrinsic a-Si:H and a-SiC:H upon light soaking was investigated by the photomixing technique. The photoconductivity, lifetime and drift mobility in intrinsic hydrogenated amorphous silicon (a-Si:H) and hydrogenated amorphous silicon carbide (a-SiC:H) while light-soaking were determined using a photomixing technique. In addition to the decay of the photoconductivity and electron lifetime, continuous decay of the electron drift mobility was found during the light soaking process, which reveals a new phenomenon associated with the Staebler-Wronski effect. The drift mobility decreased by a factor of 2 for 20 hour light soaking at 2.5 sun intensity. Experimental data were fitted to a stretched exponential law. Different stretched-exponential parameters for photoconductivity, lifetime and drift mobility were obtained, which indicates the production of defects with different generation kinetics upon light soaking.

Braunstein, R.; Yang, Y.; Dong, S. [Univ. of California, Los Angeles, CA (United States)

1995-10-01T23:59:59.000Z

63

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

DOE Green Energy (OSTI)

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.

Guha, S.; Yang, J.

2005-10-01T23:59:59.000Z

64

Techniques for measuring the composition of hydrogenated amorphous silicon-germanium alloys  

DOE Green Energy (OSTI)

The authors grow hydrogenated amorphous silicon-germanium alloys by the hot-wire chemical vapor deposition technique at deposition rates between 0.5 and 1.4 nanometers per second. They prepared a set of these alloys to determine the concentrations of the alloying elements as measured by various techniques. This set consists of samples throughout the range of germanium alloying from 0% (a-Si:H) to 100% (a-Ge:H). They find that by making the appropriate calibrations and corrections, their compositional measurements agreement between the various techniques. Nuclear reaction analysis, Fourier transform infrared spectroscopy, and secondary ion mass spectrometry (SIMS) all yield similar hydrogen contents, within {+-}20% for each sample. Electron probe micro-analysis (EPMA) and SIMS yield silicon and germanium contents within {+-}7% of each other with results being confirmed by Rutherford backscattering. EPMA oxygen measurements are affected by highly oxidized surface layers, thus these data show larger O concentrations than those measured by SIMS.

Nelson, B.P.; Xu, Y.; Webb, J.D.; Mason, A.; Reedy, R.C.; Gedvilas, L.M.; Lanford, W.A.

1999-10-25T23:59:59.000Z

65

Amorphous silicon-carbon thin films  

DOE Green Energy (OSTI)

This study has shown that it is possible to produce nearly stoichiometric films of a-SiC:H with high hydrogen content by rf sputtering in an atmosphere of argon, propane, and hydrogen. The a-SiC films adhere to a variety of substrates and exhibit better thermal stability than a-Si:H films. The index of refraction is 2.8. The optical gap energy of these films is between 2.0 and 2.2 eV. A series of isochronal annealing steps show that optical gap energies decrease, optical absorption edge widths increase, and that the minimum optical density in the low absorption region increases with annealing above 450/sup 0/C. Infrared measurements show large absorptions at 2100, 1000, 750, and 650 cm/sup -1/ corresponding to SiH stretch, CH wagging, SiC stretch, and SiH wagging vibrational modes. The CH/sub n/ stretch mode near 2900 cm/sup -1/ is very small. Isochronal annealing causes a nearly continuous decrease in the integrated intensity of the SiH stretch mode at 2100 cm/sup -1/. The 2100 absorption peak shape may indicate the presence of SiH/sub 2/ in the film. Comparison of the 2100 and 750 absorption peaks show that the Si-C bonds are more heat resistant than the Si-H bonds. Annealing experiments reveal that the decrease in optical gap energy with increasing annealing temperature is probably not due to change in the Si-H bonds. Rather, the decrease is most likely due to changes or breaks in the C-H bonds and possibly the Si-C bonds. NMR results show that the films have high hydrogen concentrations. Also, NMR results and the integrated intensity for the SiH stretch mode give correct order of magnitude determination of the number and concentration of Si-H bonds in the a-SiC:H films.

Ward, J.F.

1983-09-01T23:59:59.000Z

66

Characterization of Amorphous Silicon Advanced Materials and PV Devices: Final Technical Report, 15 December 2001--31 January 2005  

DOE Green Energy (OSTI)

The major objectives of this subcontract have been: (1) understand the microscopic properties of the defects that contribute to the Staebler-Wronski effect to eliminate this effect, (2) perform correlated studies on films and devices made by novel techniques, especially those with promise to improve stability or deposition rates, (3) understand the structural, electronic, and optical properties of films of hydrogenated amorphous silicon (a-Si:H) made on the boundary between the amorphous and microcrystalline phases, (4) search for more stable intrinsic layers of a-Si:H, (5) characterize the important defects, impurities, and metastabilities in the bulk and at surfaces and interfaces in a-Si:H films and devices and in important alloy systems, and (6) make state-of-the-art plasma-enhanced chemical vapor deposition (PECVD) devices out of new, advanced materials, when appropriate. All of these goals are highly relevant to improving photovoltaic devices based on a-Si:H and related alloys. With regard to the first objective, we have identified a paired hydrogen site that may be the defect that stabilizes the silicon dangling bonds formed in the Staebler-Wronski effect.

Taylor, P. C.

2005-11-01T23:59:59.000Z

67

Characterization for the Onset of Crystallization of Amorphous to Microcrystalline Silicon by Optical Spectroscopies  

DOE Green Energy (OSTI)

We study the amorphous to microcrystalline silicon films made at three laboratories by using Raman, photoluminescence- and optical-abosrption spectroscopies.

Yue, G.; Han, D.; Ganguly, G.; Wang, Q.; Yang, J.; Guha, S.

2000-01-01T23:59:59.000Z

68

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

DOE Green Energy (OSTI)

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.

Guha, S.

2001-11-08T23:59:59.000Z

69

Electrospun a-Si using Liquid Silane/Polymer Inks  

DOE Green Energy (OSTI)

Amorphous silicon nanowires (a-SiNWs) were prepared by electrospinning cyclohexasilane (Si{sub 6}H{sub 12}) admixed with polymethylmethacrylate (PMMA) in toluene. Raman spectroscopy characterization of these wires (d {approx} 50-2000 nm) shows 350 C treatment yields a-SiNWs. Porous a-SiNWs are obtained using a volatile polymer.

D.L. Schulz; J.M. Hoey; J. Smith; J. Lovaasen; C. Braun; X. Dai; K. Anderson; A. Elangovan; X. Wu; S. Payne; K. Pokhodnya; I. Akhatov; L. Pederson; P. Boudjouk

2010-12-01T23:59:59.000Z

70

Electrospun a-Si using Liquid Silane/Polymer Inks  

DOE Green Energy (OSTI)

Amorphous silicon nanowires (a-SiNWs) were prepared by electrospinning cyclohexasilane (Si{sub 6}H{sub 12}) admixed with polymethylmethacrylate (PMMA) in toluene. Raman spectroscopy characterization of these wires (d {approx} 50-2000 nm) shows 350 C treatment yields a-SiNWs. Porous a-SiNWs are obtained using a volatile polymer.

Doug Schulz

2010-12-09T23:59:59.000Z

71

Photoluminescence in silicon implanted with silicon ions at amorphizing doses  

Science Conference Proceedings (OSTI)

Luminescent and structural properties of n-FZ-Si and n-Cz-Si implanted with Si ions at amorphizing doses and annealed at 1100 Degree-Sign C in a chlorine-containing atmosphere have been studied. An analysis of proton Rutherford backscattering spectra of implanted samples demonstrated that an amorphous layer is formed, and its position and thickness depend on the implantation dose. An X-ray diffraction analysis revealed that defects of the interstitial type are formed in the samples upon annealing. Photoluminescence spectra measured at 78 K and low excitation levels are dominated by the dislocation-related line D1, which is also observed at 300 K. The peak position of this line, its full width at half-maximum, and intensity depend on the conduction type of Si and implantation dose. As the luminescence excitation power is raised, a continuous band appears in the spectrum. A model is suggested that explains the fundamental aspects of the behavior of the photoluminescence spectra in relation to the experimental conditions.

Sobolev, N. A., E-mail: nick@sobolev.ioffe.rssi.ru; Kalyadin, A. E.; Kyutt, R. N.; Sakharov, V. I.; Serenkov, I. T.; Shek, E. I.; Afrosimov, V. V. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Tetel'baum, D. I. [Lobachevsky State University, Physicotechnical Research Institute (Russian Federation)

2011-09-15T23:59:59.000Z

72

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

DOE Green Energy (OSTI)

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.

Guha, S. [United Solar Systems Corp., Troy, MI (United States)

1997-11-01T23:59:59.000Z

73

Amorphous silicon research Phase I. Annual subcontract report, August 1, 1994--July 31, 1995  

DOE Green Energy (OSTI)

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 multifunction hydrogenated amorphous silicon (a-Si:H) alloy modules. The near-term goal of the program is to achieve 12% stable efficiency by 1998 using the multifunction approach. 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. The bulk of the effort was directed toward the middle and bottom cell structure. 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.

Guha, S. [United Solar Systems Corp., Troy, MI (United States)

1995-10-01T23:59:59.000Z

74

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

SciTech Connect

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.

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

1991-06-01T23:59:59.000Z

75

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

DOE Green Energy (OSTI)

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.

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

1991-06-01T23:59:59.000Z

76

Sputtered pin amorphous silicon semi-conductor device and method therefor  

DOE Patents (OSTI)

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.

Moustakas, Theodore D. (Berkeley Heights, NJ); Friedman, Robert A. (Milford, NJ)

1983-11-22T23:59:59.000Z

77

Chemical vapor deposition of amorphous silicon films from disilane  

SciTech Connect

Amorphous silicon films for fabrication of solar cells have been deposited by thermal chemical vapor deposition (CVD) from disilane (Si/sub 2/H/sub 6/) using a tubular flow reactor. A mathematical description for the CVD reactor was developed and solved by a numerical procedure. The proposed chemical reaction network for the model is based on silylene (SiH/sub 2/) insertion in the gas phase and film growth from SiH/sub 2/ and silicon polymers (Si/sub n/N/sub 2n/, n approx. 10). Estimates of the rate constants have been obtained for trisilane decomposition, silicon polymer formation, and polymer dehydrogenation. The silane unimolecular decomposition rate constants were corrected for pressure effects. The model behavior is compared to the experimental results over the range of conditions: reactor temperature (360 to 485/sup 0/C), pressures (2 to 48 torr), and gas holding time (1 to 70 s). Within the above range of conditions, film growth rate varies from 0.01 to 30 A/s. Results indicate that silicon polymers are the main film precursors for gas holding times greater than 3 s. Film growth by silylene only becomes important at short holding times, large inert gas dilution, and positions near the beginning of the reactor hot zone.

Bogaert, R.J.

1986-01-01T23:59:59.000Z

78

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

DOE Patents (OSTI)

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.

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

1998-07-07T23:59:59.000Z

79

Task B: Research on stable, high-efficiency, large-area, amorphous-silicon-based submodules: Semiannual subcontract report, 1 February 1987--31 July 1987  

DOE Green Energy (OSTI)

This semiannual report presents results of research on stable, high-efficiency, large-area, amorphous-silicon-based submodules. High conversion efficiencies (up to 11.95%) were obtained in small-area, single-junction, a-Si solar cells by using textured tin oxide, superlattice p-layers, graded carbon concentrations near the p-i interface, and highly relective ITO/silver back contacts. Researchers also fabricated single-junction a-SiC and a-SiGe p-i-n cells with efficiencies of 9%--11%. Stacked-junction cells of a-SiC/a-Si, a-SiC/a-SiGe, and a-SiC/a-Si/a-SiGe were fabricated, and efficiencies of about 10% were achieved in some of them. Boron-doped microcrystalline SiC films were developed that contain up to 6 at.% C with conductivities of 3 /times/ 10/sup /minus/3/ ohm /sup /minus/1/ cm/sup /minus/1/ at room temperature and activation energies of 0.11 eV. Stability studies showed that light-induced degradation is usually enhanced by the presence of C grading near the p-i interface. Light-induced degradation of the fill factor of p-i-n cells strongly correlates with optical absorption at 1.2 eV, as measured by photothermal deflection spectroscopy. 11 refs., 70 figs., 16 tabs.

Carlson, D.E.; Arya, R.R.; Bennett, M.S.; Catalano, A.; D'Aiello, R.V.; Dickson, C.R.; Fortmann, C.M.; Goldstein, B.; Morris, J.; Newton, J.L.

1988-07-01T23:59:59.000Z

80

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

DOE Green Energy (OSTI)

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.

Gordon, R.G. [Harvard Univ., Cambridge, MA (United States)

1995-10-01T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

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

DOE Green Energy (OSTI)

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.

Guha, S. [United Solar Systems Corp., Troy, MI (United States)

1994-10-01T23:59:59.000Z

82

Plasma-assisted CVD of fluorinated, hydrogenated amorphous silicon. Final technical report, September 15, 1979-September 15, 1980  

DOE Green Energy (OSTI)

During the past year, approximately 300 large-area (400 cm/sup 2/) PIN hydrogenated amorphous silicon (a-Si:H) solar cells were fabricated and tested. a-Si:H PIN cells which were plasma deposited at 200/sup 0/ to 350/sup 0/ were found to have high internal currents (13mA/cm/sup 2/), whereas those which were deposited by CVD at 500/sup 0/ to 650/sup 0/C had low internal currents. When corrected for optical losses in the top electrode, the internal quantum efficiency vs wavelength for the PIN cells indicated a peak value above 80% at about 525nm, which decreased monotonically to zero at about 725 nm. When the published values of RCA and EXXON were corrected similarly for optical loss, nearly identical values of internal quantum efficiencies were found. Calculations based on a model proposed by Cody et al of EXXON indicated that the depletion width was less than 0.4 microns for all PIN cells, thereby limiting junction efficiency in the red portion of the solar spectrum since the 1/e photon range exceeds this value. A novel inverted NIP cell was tested and found to have its maximum quantum response shifted to 625 nm. Also, an amorphous boron (a-B) layer deposited on a-Si:H to form a PIN heterojunction improved blue response and Voc. A combination of the red-responsive cells and the a-B heterojunction cells could raise efficiency to 8%.

Coleman, J. H.; Hammes, J. P.; Wiesmann, H. J.

1980-01-01T23:59:59.000Z

83

Amorphous silicon research. Final technical progress report, 1 August 1994--28 February 1998  

DOE Green Energy (OSTI)

This report describes the status and accomplishments of work performed under this subcontract by United Solar Systems. United Solar researchers explored several new deposition regimes/conditions to investigate their effect on material/device performance. To facilitate optimum ion bombardment during growth, a large parameter space involving chamber pressure, rf power, and hydrogen dilution were investigated. United Solar carried out a series of experiments using discharge modulation at various pulsed-plasma intervals to study the effect of Si-particle incorporation on solar cell performance. Hydrogen dilution during deposition is found to improve both the initial and stable performance of a-Si and a-SiGe alloy cells. Researchers conducted a series of temperature-ramping experiments on samples prepared with high and low hydrogen dilutions to study the effect of hydrogen effusion on solar cell performance. Using an internal photoemission method, the electrical bandgap of a microcrystalline p layer used in high-efficiency solar cells was measured to be 1.6 eV. New measurement techniques were developed to evaluate the interface and bulk contributions of losses to solar cell performance. Researchers replaced hydrogen with deuterium and found deuterated amorphous silicon alloy solar cells exhibit reduced light-induced degradation. The incorporation of a microcrystalline n layer in a multijunction cell is seen to improve cell performance. United Solar achieved a world-record single-junction a-Si alloy stable cell efficiency of 9.2% with an active area of 0.25 cm{sup 2} grown with high hydrogen dilution. They also achieved a world-record triple-junction, stable, active-area cell efficiency of 13.0% with an active area of 0.25 cm{sup 2}.

Guha, S. [United Solar Systems Corp., Troy, MI (United States)

1998-05-01T23:59:59.000Z

84

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

DOE Patents (OSTI)

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.

Carlson, David E. (Yardley, PA); Wronski, Christopher R. (Princeton, NJ)

1979-01-01T23:59:59.000Z

85

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

DOE Green Energy (OSTI)

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.

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

2000-01-01T23:59:59.000Z

86

Amorphous silicon cell array powered solar tracking apparatus  

DOE Patents (OSTI)

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.

Hanak, Joseph J. (Lawrenceville, NJ)

1985-01-01T23:59:59.000Z

87

Research on stable, high-efficiency amorphous silicon multijunction modules  

DOE Green Energy (OSTI)

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.

Guha, S. (United Solar Systems Corp., Troy, MI (United States))

1991-12-01T23:59:59.000Z

88

Research on stable, high-efficiency amorphous silicon multijunction modules  

DOE Green Energy (OSTI)

This report describes the progress made during Phase 1 of research and development program to obtain high-efficiency amorphous silicon alloy multijunction modules. Using a large-area deposition system, double-and triple-junction cells were made on stainless steel substrates of over 1 ft{sup 2} area with Ag and ZnO predeposited back reflector. Modules of over 1 ft{sup 2} were produced with between 9.2% and 9.9 initial aperture-area efficiencies as measured under a USSC Spire solar simulator. Efficiencies as measured under the NREL Spire solar simulator were found to be typically 15% to 18% lower. The causes for this discrepancy are now being investigated. The modules show about 15% degradation after 600 hours of one-sun illumination at 50{degrees}C. To optimize devices for higher stabilized efficiency, a new method was developed by which the performance of single-junction cells after long-term, one-sun exposure at 50{degrees}C can be predicted by exposing cells to short-term intense light at different temperatures. This method is being used to optimize the component cells of the multijunction structure to obtain the highest light-degraded efficiency.

Banerjee, A.; Chen, E.; Clough, R.; Glatfelter, T.; Guha, S.; Hammond, G.; Hopson, M.; Jackett, N.; Lycette, M.; Noch, J.; Palmer, T.; Pawlikiewicz, A.; Rosenstein, I.; Ross, R.; Wolf, D.; Xu, X.; Yang, J.; Younan, K.

1992-04-01T23:59:59.000Z

89

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

SciTech Connect

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.

Carlson, David E. (Yardley, PA)

1980-01-01T23:59:59.000Z

90

Photochemical vapor deposition of undoped and n-type amorphous silicon films produced from disilane  

SciTech Connect

Hydrogenated amorphous silicon films have been deposited by mercury photosensitized decomposition (photochemical vapor deposition: photo-CVD) of disilane at a substrate temperature below 300 /sup 0/C. The structural and optical properties of undoped films are very similar to those of films deposited by rf glow discharge decomposition. The electronic property measurement shows that the conductivity strongly depends on the substrate temperature during deposition. The photoconductivity reaches 5.7 x 10/sup -3/ (..cap omega.. cm)/sup -1/ (AM1,100 mW/cm/sup 2/) at a substrate temperature of 200 /sup 0/C. The dark conductivity is 10/sup -6/--10/sup -8/ (..cap omega.. cm)/sup -1/ and the Fermi level is located near the middle of the gap. n-type doping has been also achieved by adding phosphine as an impurity to disilane. Furthermore, a p-i-n a-Si solar cell was fabricated using photo-CVD undoped and P-doped films. The initial cell showed a conversion efficiency of 4.39% under AM1 insolation.

Inoue, T.; Konagai, M.; Takahashi, K.

1983-10-15T23:59:59.000Z

91

Research on High-Bandgap Materials and Amorphous Silicon-Based Solar Cells, Final Technical Report, 15 May 1994-15 January 1998  

DOE Green Energy (OSTI)

This report describes work performed by Syracuse University under this subcontract. Researchers developed a technique based on electroabsorption measurements for obtaining quantitative estimates of the built-in potential Vbi in a-Si:H-based heterostructure solar cells incorporating microcrystalline or a-SiC:H p layers. Using this new electroabsorption technique, researchers confirmed previous estimates of Vbi {yields} 1.0 V in a-Si:H solar cells with ''conventional'' intrinsic layers and either microcrystalline or a-SiC:H p layers. Researchers also explored the recent claim that light-soaking of a-Si:H substantially changes the polarized electroabsorption associated with interband optical transitions (and hence, not defect transitions). Researchers confirmed measurements of improved (5') hole drift mobilities in some specially prepared a-Si:H samples. Disturbingly, solar cells made with such materials did not show improved efficiencies. Researchers significantly clarified the relationship of ambipolar diffusion-length measurements to hole drift mobilities in a-Si:H, and have shown that the photocapacitance measurements can be interpreted in terms of hole drift mobilities in amorphous silicon. They also completed a survey of thin BP:H and BPC:H films prepared by plasma deposition using phosphine, diborane, trimethylboron, and hydrogen as precursor gases.

Schiff, E. A.; Gu, Q.; Jiang, L.; Lyou, J.; Nurdjaja, I.; Rao, P. (Department of Physics, Syracuse University)

1998-12-28T23:59:59.000Z

92

High Growth Rate Deposition of Hydrogenated Amorphous Silicon-Germanium Films and Devices Using ECR-PECVD  

DOE Green Energy (OSTI)

Hydrogenated amorphous silicon germanium films (a-SiGe:H) and devices have been extensively studied because of the tunable band gap for matching the solar spectrum and mature the fabrication techniques. a-SiGe:H thin film solar cells have great potential for commercial manufacture because of very low cost and adaptability to large-scale manufacturing. Although it has been demonstrated that a-SiGe:H thin films and devices with good quality can be produced successfully, some issues regarding growth chemistry have remained yet unexplored, such as the hydrogen and inert-gas dilution, bombardment effect, and chemical annealing, to name a few. The alloying of the SiGe introduces above an order-of-magnitude higher defect density, which degrades the performance of the a-SiGe:H thin film solar cells. This degradation becomes worse when high growth-rate deposition is required. Preferential attachment of hydrogen to silicon, clustering of Ge and Si, and columnar structure and buried dihydride radicals make the film intolerably bad. The work presented here uses the Electron-Cyclotron-Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) technique to fabricate a-SiGe:H films and devices with high growth rates. Helium gas, together with a small amount of H{sub 2}, was used as the plasma species. Thickness, optical band gap, conductivity, Urbach energy, mobility-lifetime product, I-V curve, and quantum efficiency were characterized during the process of pursuing good materials. The microstructure of the a-(Si,Ge):H material was probed by Fourier-Transform Infrared spectroscopy. They found that the advantages of using helium as the main plasma species are: (1) high growth rate--the energetic helium ions break the reactive gas more efficiently than hydrogen ions; (2) homogeneous growth--heavy helium ions impinging on the surface promote the surface mobility of the reactive radicals, so that heteroepitaxy growth as clustering of Ge and Si, columnar structure are reduced; (3) surface hydrogen removal--heavier and more energetic helium ions break the Si-H much easier than hydrogen ions. The preferential attachment of Si-H to Ge-H is reduced. They also found that with the small amount of hydrogen put into the plasma, the superior properties of a-(Si,Ge):H made from pure hydrogen dilution plasma were still maintained. These hydrogen ions help to remove the subsurface weakly bonded hydrogen and buried hydrogen. They also help to passivate the Ge-dangling bond.

Yong Liu

2002-05-31T23:59:59.000Z

93

Research on stable, high-efficiency amorphous silicon multijunction modules. Semiannual subcontract report, 1 January 1992--30 June 1992  

DOE Green Energy (OSTI)

This report describes research on semiconductor and non-semiconductor materials to enhance the performance of multi-band-gap, multijunction panel with an area greater than 900 cm{sup 2} by 1992. Double-junction and triple-junction cells are mode on a Ag/ZnO back reflector deposited on stainless steel substrates. An a-SiGe alloy is used for the i-layer in the bottom and the middle cells; the top cell uses an amorphous silicon alloy. After the evaporation of an 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 1-ft{sup 2} monolithic module.

Guha, S. [United Solar Systems Corp., Troy, MI (United States)

1992-09-01T23:59:59.000Z

94

Photocharge Transport and Recombination Measurements in Amorphous Silicon Films and Solar Cells by Photoconductive Frequency Mixing: Final Subcontract Report: 13 May 1994 - 15 January 1998  

DOE Green Energy (OSTI)

This report describes work performed during this subcontract by the University of California. The photoconductivity, lifetime, and drift mobility of intrinsic hydrogenated amorphous silicon (a-Si:H), hydrogenated amorphous silicon carbide (a-SiC:H), and hydrogenated amorphous silicon germanium (a-SiGe:H) were determined using a photomixing technique in the as prepared and light-soaked states. In addition to the decay of the photoconductivity and electron lifetime, continuous decay of the electron drift mobility was found during the light-soaking process (Staebler-Wronski effect). Experimental data were fitted to a stretched exponential law. Different stretched-exponential parameters for photoconductivity, lifetime, and drift mobility were obtained, which indicates the production of defects with different generation kinetics upon light soaking. The transport properties of intrinsic a-Si:H samples (which were produced by the hot-wire technique at NREL at different substrate temperatures such that the hydrogen content ranged from >10% to <1%), were systematically studied. It was found that with increasing substrate temperature, the lifetime, the drift mobility, and the photoconductivity decreased, but the Urbach energy ({approx} 0.1 eV below the conduction band) increased. These results indicate that for the a-Si:H films with increasing deposition temperature, the density of positively charged, negatively charged, and neutral defects all show a tendency to increase, in agreement with the results observed by other workers employing other measurement techniques. Researchers also found that the drift mobility of these samples increases and the lifetime decreases with increasing electric field, while the mt product is essentially independent of the electric field in the range of 1,000-10,000 V/cm. The electric field dependence of mobility (Dm) /m0/ (DE) in the as-grown or/and annealed states are always larger than that in the light-soaked state. This electric field dependence of mobility can be explained by the existence of long-range potential fluctuations. Photoemission measurements in air were performed on a-Si:H, a-SiC:H, and transparent conducting oxide layers, and revealed inhomogeneities of composition or surface contamination.

Braunstein, R.; Tang, Y.; Dong, S.; Liebe, J.; Sun, G.; Kattwinkel, A. (University of California: Los Angeles, California)

1999-05-04T23:59:59.000Z

95

Available Technologies:Improved Amorphous Silicon Solar Cells  

Solar cells; Large solar panels; ADVANTAGES. Increased performance ; Less expensive than crystalline silicon solar cells; Enables thinner, lighter solar panels;

96

The specific heat of pure and hydrogenated amorphous silicon  

E-Print Network (OSTI)

Summary of data for heat capacity samples. T S is the growthSummary of HWCVD a-Si:H heat capacity results. The data forv Total measured heat capacity c T of a 50 nm thick device

Queen, Daniel Robert

2011-01-01T23:59:59.000Z

97

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

DOE Patents (OSTI)

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.

Moustakas, Theodore D. (Berkeley Heights, NJ); Morel, Don L. (Woodland Hills, CA); Abeles, Benjamin (Princeton, NJ)

1983-10-04T23:59:59.000Z

98

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

DOE Green Energy (OSTI)

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.

Arya, R.R.; Bennett, M.; Bradley, D. [and others

1996-02-01T23:59:59.000Z

99

Status of Amorphous and Crystalline Thin Film Silicon Solar Cell Activities  

DOE Green Energy (OSTI)

This paper reviews the recent activities and accomplishments of the national Amorphous Silicon Team and a (crystalline) thin-film-Si subteam that was implemented in 2002 to research solar cell devices based on thin crystalline Si based layers. This paper reports the evolution of team organization, the technical highlights from the recent team meetings, and an outlook on commercialization potential.

von Roedern, B.

2003-05-01T23:59:59.000Z

100

Atomic-scale characterization of hydrogenated amorphous-silicon films and devices. Annual subcontract report, 14 February 1994--14 April 1995  

DOE Green Energy (OSTI)

Properties of the hydrogenated amorphous silicon (a-Si:H) films used in photovoltaic (PV) panels are reported. The atomic-scale topology of the surface of intrinsic a-Si:H films, measured by scanning tunneling microscopy (STM) as a function of film thickness, are reported and diagnosed. For 1-500-nm-thick films deposited under normal device-quality conditions from silane discharges, most portions of these surfaces are uniformly hilly without indications of void regions. However, the STM images indicate that 2-6-nm silicon particulates are continuously deposited into the growing film from the discharge and fill approximately 0.01% of the film volume. Although the STM data are not sensitive to the local electronic properties near these particulates, it is very likely that the void regions grow around them and have a deleterious effect on a-Si:H photovoltaics. Preliminary observations of particulates in the discharge, based on light scattering, confirm that particulates are present in the discharge and that many collect and agglomerate immediately downstream of the electrodes. Progress toward STM measurements of the electronic properties of cross-sectioned a-Si:H PV cells is also reported.

Gallagher, A.; Tanenbaum, D.; Laracuente, A.; Jelenkovic, B. [National Inst. of Standards and Technology, Boulder, CO (United States)

1995-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

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

DOE Green Energy (OSTI)

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.

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

2000-01-01T23:59:59.000Z

102

Amorphous silicon photovoltaic devices prepared by chemical and photochemical vapor deposition of higher order silanes. Annual subcontract progress report, 1 September 1984-31 August 1985  

DOE Green Energy (OSTI)

This report describes the preparation of hydrogenated amorphous silicon (a-Si:H) films and photovoltaic devices by chemical vapor deposition (CVD) from higher order silanes and the properties of such films and devices. The research explored new deposition techniques that could produce a-Si:H superior to that achieved by the glow-discharge method. For example, the improvement could stem from ease of deposition (lower cost and/or better reproducibility), from material improvement (higher efficiency and/or better stability under illumination), or from innovative materials that improve device performance. Research focused on photo-CVD techniques; thermal CVD deemphasized. This report presents results for deposition by mercury-sensitized decomposition of disilane. These results indicate that this technique is a very promising alternative to the glow-discharge method.

Delahoy, A.E.; Ellis, F.B. Jr.

1985-11-01T23:59:59.000Z

103

Amorphous silicon photovoltaic devices prepared by chemical and photochemical vapor deposition of higher order silanes. Technical progress report, 1 September 1984-28 February 1985  

DOE Green Energy (OSTI)

This report describes the preparation of hydrogenated amorphous silicon (a-Si:H) films and photovoltaic devices by chemical vapor deposition (CVD) from higher order silanes, and the properties of such films and devices. The research is directed at exploring new, improved deposition techniques to produce a-Si:H. The improvement could stem from ease of deposition (lower cost and/or better reproducibility), from material improvement (higher efficiency and/or better stability under illumination), or from innovative materials that improve device performance. Research efforts have focused, therefore, on photo-CVD techniques; thermal CVD has been emphasized. This report summarizes the properties of the experimental thermal CVD films and the reasons for terminating the research in this area. In addition, the results for deposition by mercury-sensitized decomposition of disilane are presented. These results indicate that this technique is a very promising alternative to the glow-discharge method.

Delahoy, A.E.; Ellis, F.B. Jr.

1985-05-01T23:59:59.000Z

104

Photocharge transport and recombination measurements in amorphous silicon films and solar cells by photoconductive frequency mixing. Annual subcontract report, 15 May 1995--15 May 1996  

DOE Green Energy (OSTI)

Using the photomixing technique, the authors systematically studied the transport properties of intrinsic hydrogenated amorphous silicon (a-Si:H) samples that had hydrogen content ranging from over 10% to less than 1% and which were produced by the hot-wire technique at NREL. They investigated the continuous decay of electron drift mobility in intrinsic a-Si:H on light-soaking and determined the degradation of photoconductivity, lifetime, and drift mobility in these a-Si:H samples while light-soaking. In addition to the decay of the photoconductivity and electron lifetime, continuous decay of the electron drift mobility was found during the light-soaking process, which reveals a new phenomenon associated with the Staebler-Wronski effect. The drift mobility decreased by a factor of 2--4 for 5-hour light-soaking at 4-sun intensity. The authors investigated the effects of deposition conditions on transport properties of intrinsic a-Si:H films and, by using the photomixing technique, they determined the electron drift mobility, lifetime, and the conduction-band Urbach energy of a-Si:H films as a function of substrate temperature. 44 refs.

Braunstein, R.; Dong, S. [California Univ., Los Angeles, CA (United States)

1996-10-01T23:59:59.000Z

105

Exchange of bonded hydrogen in amorphous silicon by deuterium  

DOE Green Energy (OSTI)

We show that bonded hydrogen in a-Si:H is readily exchanged by atomic deuterium when exposed to a deuterium plasma discharge. The effective diffusion coefficient for the D,H exchange 10/sup -14/ cm/sup 2//sec at 160/sup 0/C, is comparable to that of interstitial hydrogen in c-Si.

Abeles, B.; Yang, L.; Leta, D.P.; Majkrzak, C.F.

1986-12-01T23:59:59.000Z

106

HIGHLY STABLE AMORPHOUS SILICON THIN FILM TRANSISTORS AND INTEGRATION  

E-Print Network (OSTI)

ORGANIC LIGHT EMITTING DIODE DISPLAYS ON CLEAR PLASTIC Bahman Hekmatshoar A DISSERTATION PRESENTED insensitive to the TFT threshold voltage rise which is well-known in a-Si:H devices. Organic light-emitting diodes (OLEDs) are a future technology choice for flexible displays with several advantages over liquid

107

Amorphous Silicon(a-Si: H) Thin Film Based Omnidirectional Control Solar Powered Vehicle  

Science Conference Proceedings (OSTI)

Through the paper, our goal is to drive a car with the help of thin film based solar cell. Mechanical and Electrical parts are assembled thereby. The main objective of this project is to collect maximum solar energy from the solar spectrum and use that ... Keywords: Thin film Photovoltaic, Single p-i-n Junction, Steering Mechanism, H-Bridge, Gear motor

Abdullah Moinuddin; Md. Jahidul Hoque; Jony C. Sarker; Akhter Zia

2012-03-01T23:59:59.000Z

108

Electron energy-loss spectroscopy of boron-doped layers in amorphous thin film silicon solar cells  

E-Print Network (OSTI)

Electron energy-loss spectroscopy of boron-doped layers in amorphous thin film silicon solar cells. de Bariloche, Argentina 3 ECN Solar Energy, High Tech Campus, Building 5, 5656 AE Eindhoven energy-loss spectroscopy (EELS) is used to study p-doped layers in n-i-p amorphous thin film Si solar

Dunin-Borkowski, Rafal E.

109

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

DOE Green Energy (OSTI)

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.

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

2012-06-01T23:59:59.000Z

110

Atomic-scale characterization of hydrogenated amorphous-silicon films and devices. Annual subcontract report, 15 April 1994--14 March 1998  

DOE Green Energy (OSTI)

The research is concerned with improving the electronic properties of hydrogenated amorphous silicon (a-Si:H) films and of photovoltaic (PV) cells that use these films. Two approaches toward this goal are being taken. One is to establish the character of silicon particle growth in the rf glow discharges that are used to make the films and PV cells, and to understand the particle incorporation into the films. The ultimate goal of this effort is to find mitigation techniques that minimize the particle incorporation. During this contract period the authors have developed a novel particle light-scattering technique that provides a detailed and sensitive diagnostic of small (8-60 nm diameter) particles suspended in the discharge. The authors have used this to measure the particle growth rates and densities, versus conditions in pure-silane discharges. The second program is directed toward measuring the electronic properties of thin-film PV cells, as a function of depth within the cell. The approach being taken is to use a scanning tunneling microscope (STM) to measure the depth-dependent electronic properties of cross-sectioned PV cells. During the present period, measurements on single and tandem amorphous silicon cells have been carried out. Using STM current-voltage spectroscopy, these measurements distinguish the boundaries between the highly-conducting and intrinsic layers, as well as the chemical potential versus depth in the cell.

Gallagher, A.; Barzen, S.; Childs, M.; Laracuente, A. [National Inst. of Standards and Technology, Boulder, CO (United States)

1998-06-01T23:59:59.000Z

111

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

DOE Patents (OSTI)

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.

Hanak, Joseph J. (Lawrenceville, NJ)

1985-06-25T23:59:59.000Z

112

Diagnostics of a glow discharge used to produce hydrogenated amorphous silicon films. Final subcontract report  

DOE Green Energy (OSTI)

This report and recent publications cited summarize our measurements of the neutral radicals produced in pure silane discharges, our measurements of the interaction of silane with a growing amorphous silicon surface, qualitative models of discharge neutral radical chemistry, and quantitative models of dc discharge ion chemistry. All radicals of the monosilane and disilane groups have been measured and are reported as a function of discharge parameters, but not yet for the full range of parameters that must be investigated for detailed analysis. Observations of the reaction of SiH/sub 4/ with a hot amorphous silicon surface are given. These are closely related to the dominant discharge film deposition mechanism of SiH/sub 3/ reacting with a hydrogen covered amorphous silicon surface and a surface reaction model is suggested that explains some but not all of our data. The dc discharge model is used to obtain quantitative predictions of the ion species at the cathode surface of a dc discharge. This is compared to observations and used to explain the observations at our laboratory and other laboratories. We conclude that most but not all features of the ion chemistry in dc discharges of pure silane can be relatively well understood from this model.

Gallagher, A.

1984-11-01T23:59:59.000Z

113

Research on defects and transport in amorphous-silicon-based semiconductors. Final subcontract report, 20 February 1991--19 April 1994  

DOE Green Energy (OSTI)

This report describes work on three individual tasks as follows. (1) Electron and hole drift measurements in a-Si{sub 1-x}Ge{sub x}:H and a-Si{sub 1-x}C{sub x}:H p-i-n solar cells. Multijunction solar cells incorporating modified band gap a-Si:H in a triple-junction structure are generally viewed as the most promising avenue for achieving an amorphous silicon-based solar call with 15% stabilized conversion efficiency. The specific objective of this task was to document the mobilities and deep-trapping mobility-lifetime products for electrons and holes in a-Si{sub 1-x}Ge{sub x}:H and a-Si{sub 1-x}C{sub x}:H alloys materials. (2) Electroabsorption measurements and built-in potential (V{sub bi}) in solar cells. V{sub bi} in a p-i-n solar call may be limiting the open-circuit voltage (V{sub oc}) in wide-band-gap cells (E{sub g} > 1.8 eV) currently under investigation as the top cell for 15% triple junction devices. The research addressed four issues that need to be resolved before the method can yield an error less than 0.1 V for V{sub bi}. The details are presented in this report. (3) Defect relaxation and Shockley-Read kinetics in a-Si:H. Quantitative modeling of solar cells is usually based on Shockley-Read kinetics.`` An important assumption of this approach is that the rate of emission of a photocarrier trapped on a defect is independent of quasi-Fermi level location.

Schiff, E.A.; Antoniadis, H.; Gu, Q.; Lee, J.K.; Wang, Q.; Zafar, S. [Syracuse Univ., NY (United States)

1994-09-01T23:59:59.000Z

114

Detection of charged particles and X-rays by scintillator layers coupled to amorphous silicon photodiode arrays  

Science Conference Proceedings (OSTI)

Hydrogenated amorphous silicon (a-Si:H) p-i-n diodes with transparent metallic contacts are shown to be suitable for detecting charged particles, electrons, and X-rays. When coupled to a suitable scintillator using CsI(Tl) as the scintillator we show a capability to detect minimum ionizing particles with S/N {approximately}20. We demonstrate such an arrangement by operating a p-i-n diode in photovoltaic mode (reverse bias). Moreover, we show that a p-i-n diode can also work as a photoconductor under forward bias and produces a gain yield of 3-8 higher light sensitivity for shaping times of 1 {mu}s. n-i-n devices have similar optical gain as the p-i-n photoconductor for short integrating times ( radiation exposure dose can be reduced significantly. The scintillator CsI layers we made have higher spatial resolution than the Kodak commercial scintillator screens due to their internal columnar structure which can collimate the scintillation light. Evaporated CsI layers are shown to be more resistant to radiation damage than the crystalline bulk CsI(Tl).

Jing, T.; Drewery, J.; Hong, W.S.; Lee, H.; Kaplan, S.N.; Perez-Mendez, V. [Lawrence Berkeley Lab., CA (United States); Goodman, C.A.; Wildermuth, D. [Air Techniques, Inc. Hicksville, NY (United States)

1995-04-01T23:59:59.000Z

115

Detection of charged particles and X-rays by scintillator layers coupled to amorphous silicon photodiode arrays  

SciTech Connect

Hydrogenated amorphous silicon (a-Si:H) p-i-n diodes with transparent metallic contacts are shown to be suitable for detecting charged particles, electrons, and X-rays. When coupled to a suitable scintillator using CsI(Tl) as the scintillator we show a capability to detect minimum ionizing particles with S/N {approximately}20. We demonstrate such an arrangement by operating a p-i-n diode in photovoltaic mode (reverse bias). Moreover, we show that a p-i-n diode can also work as a photoconductor under forward bias and produces a gain yield of 3-8 higher light sensitivity for shaping times of 1 {mu}s. n-i-n devices have similar optical gain as the p-i-n photoconductor for short integrating times ( < 10{mu}s). However, n-i-n devices exhibit much higher gain for a long term integration (10ms) than the p-i-n ones. High sensitivity photosensors are very desirable for X-ray medical imaging because radiation exposure dose can be reduced significantly. The scintillator CsI layers we made have higher spatial resolution than the Kodak commercial scintillator screens due to their internal columnar structure which can collimate the scintillation light. Evaporated CsI layers are shown to be more resistant to radiation damage than the crystalline bulk CsI(Tl).

Jing, T.; Drewery, J.; Hong, W.S.; Lee, H.; Kaplan, S.N.; Perez-Mendez, V. [Lawrence Berkeley Lab., CA (United States); Goodman, C.A.; Wildermuth, D. [Air Techniques, Inc. Hicksville, NY (United States)

1995-04-01T23:59:59.000Z

116

[ital In] [ital situ] infrared measurements of film and gas properties during the plasma deposition of amorphous hydrogenated silicon  

SciTech Connect

This research has performed preliminary [ital in] [ital situ] Fourier transform infrared (FTIR) measurements during the plasma deposition of amorphous silicon ([ital a]-Si:H). Experiments demonstrate both gas phase and film measurements within a simple SiH[sub 4] plasma reactor using a specially modified FTIR spectrometer. Films are deposited on substrates of either gold (mirror finish) or stainless steel (matte finish). In particular, [ital in] [ital situ] emission/reflection FTIR of the film yields information about surface temperature, film thickness, and film composition. We have measured surface temperature to [plus minus]5 K and detected the onset of poor film growth at a thickness of 500--1000 A using the 2080 cm[sup [minus]1] absorption feature. A simple model for the reflectance of a film on a metal is employed to determine the thickness of the films. [ital In] [ital situ] emission/transmission FTIR of the plasma determines the gas composition and average gas temperature. Measurements show that the silane conversion is [similar to]11% within the plasma region for a typical deposition at 250 [degree]C and roughly doubles for a deposition at room temperature. The FTIR spectra show that most of this converted silane reappears as disilane (Si[sub 2]H[sub 6]). Before starting the plasma, the silane gas is [similar to]30 K cooler than the nominal substrate temperature of 250 [degree]C; starting the plasma raises the average temperature another 20 [degree]C.

Morrison, P.W. Jr.; Haigis, J.R. (Advanced Fuel Research, Inc., East Hartford, Connecticut 06108 (United States))

1993-05-01T23:59:59.000Z

117

Photocharge transport and recombination measurements in amorphous silicon films and solar cells by photoconductive frequency mixing: Annual subcontract report, 20 April 1998--19 April 1999  

DOE Green Energy (OSTI)

In the present phase of the program, the transport parameters of a number of amorphous semiconductors prepared by a number of techniques were determined by the photoconductive frequency mixing technique. This technique enabled the authors to determine the drift mobility, md, and the photomixing lifetime, t. The technique is based on the idea of heterodyne detection for photoconductors. When two similarly polarized monochromatic optical beams of slightly different frequencies are incident upon a photoconductor, the generation rate of electron-hole pairs will produce a photocurrent, when a dc-bias is applied, which will contain components resulting from the square of the sum of the individual incident fields. Consequently, a photocurrent will be produced, which will consist of a direct current and a microwave current corresponding to the beat frequency. These two currents allow a separate determination of the drift mobility and the photomixing lifetime of the photogenerated carriers. In the present work, the longitudinal modes of a He-Ne laser were employed to generate a beat frequency of 252 MHz; all the measurements were performed at this frequency for the data indicated in the accompanying figures. The following topics were explored: Measurements of the charge transport parameters of homogeneous a-SiGe:H alloys produced by NREL employing the hot-wire technique; The change in the charge transport parameters in the transition from hydrogenated amorphous silicon to microcrystalline silicon for material produced by NREL and MVSystems; The improvement in instrumentation of the photomixing measurements; Measurements of the hydrostatic dependency of the transport parameters of amorphous silicon; and Preliminary photomixing measurements on p-i-n devices.

Braunstein, R.; Kattwinkel, A.; Liebe, J.; Sun, G.

2000-02-28T23:59:59.000Z

118

Energy transfer and 1.54 {mu}m emission in amorphous silicon nitride films  

Science Conference Proceedings (OSTI)

Er-doped amorphous silicon nitride films with various Si concentrations (Er:SiN{sub x}) were fabricated by reactive magnetron cosputtering followed by thermal annealing. The effects of Si concentrations and annealing temperatures were investigated in relation to Er emission and excitation processes. Efficient excitation of Er ions was demonstrated within a broad energy spectrum and attributed to disorder-induced localized transitions in amorphous Er:SiN{sub x}. A systematic optimization of the 1.54 {mu}m emission was performed and a fundamental trade-off was discovered between Er excitation and emission efficiency due to excess Si incorporation. These results provide an alternative approach for the engineering of sensitized Si-based light sources and lasers.

Yerci, S.; Li, R. [Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215-2421 (United States); Kucheyev, S. O.; Buuren, T. van [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Basu, S. N. [Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Brookline, Massachusetts 02446 (United States); Department of Mechanical Engineering, Boston University, 110 Cummington Street, Boston, Massachusetts 02215 (United States); Dal Negro, L. [Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215-2421 (United States); Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Brookline, Massachusetts 02446 (United States)

2009-07-20T23:59:59.000Z

119

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)

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.

Moustakas, Theodore D. (Annandale, NJ); Maruska, H. Paul (Annandale, NJ)

1985-04-02T23:59:59.000Z

120

Growth mechanisms and characterization of hydrogenated amorphous- silicon-alloy films  

Science Conference Proceedings (OSTI)

This report describes an apparatus, constructed and tested, that allows measurement of the surface morphology of as-grown hydrogenated amorphous silicon films with atomic resolution using a scanning tunneling microscope. Surface topologies of 100-[degree][Lambda]-thick intrinsic films, deposited on atomically flat, crystalline Si and GaAs, are reported. These films surfaces are relatively flat on the atomic scale, indicating fairly homogeneous, compact initial film growth. The effect of probe-tip size on the observed topology and the development of atomically sharp probes is discussed. 17 refs, 9 figs.

Gallagher, A.; Ostrom, R.: Stutzin, G.; Tanenbaum, D. (National Inst. of Standards and Technology, Gaithersburg, MD (United States))

1993-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Hydrogen Flip Model for Light-Induced Changes of Amorphous Silicon  

DOE Green Energy (OSTI)

We propose a new metastable defect associated with hydrogen atoms in amorphous silicon. A higher energy metastable state is formed when H is flipped to the backside of the Si-H bond at monohydride sites. The defect is described by a double-well potential energy. The dipole moment of this {open_quotes}H-flip{close_quotes} defect is larger and increases the infrared absorption. This defect accounts for large structural changes observed on light soaking including larger infrared absorption and volume dilation. {copyright} {ital 1999} {ital The American Physical Society}

Biswas, R.; Li, Y. [Department of Physics and Astronomy, Microelectronics Research Center and Ames Laboratory--USDOE, Iowa State University, Ames, Iowa 50011 (United States)] [Department of Physics and Astronomy, Microelectronics Research Center and Ames Laboratory--USDOE, Iowa State University, Ames, Iowa 50011 (United States); Li, Y. [Department of Physics, University of Science and Technology of China, Hefei 230026, People`s Republic of (China)] [Department of Physics, University of Science and Technology of China, Hefei 230026, People`s Republic of (China)

1999-03-01T23:59:59.000Z

122

Amorphous silicon pixel layers with cesium iodide converters for medical radiography  

SciTech Connect

We describe the properties of evaporated layers of Cesium Iodide (Thallium activated) deposited on substrates that enable easy coupling to amorphous silicon pixel arrays. The CsI(Tl) layers range in thickness from 65 to 220{mu}m. We used the two-boat evaporator system to deposit CsI(Tl) layers. This system ensures the formation of the scintillator film with homogenous thallium concentration which is essential for optimizing the scintillation light emission efficiency. The Tl concentration was kept to 0.1--0.2 mole percent for the highest light output. Temperature annealing can affect the microstructure as well as light output of the CsI(Tl) film. 200--300C temperature annealing can increase the light output by a factor of two. The amorphous silicon pixel arrays are p-i-n diodes approximately l{mu}m thick with transparent electrodes to enable them to detect the scintillation light produced by X-rays incident on the CsI(Tl). Digital radiography requires a good spatial resolution. This is accomplished by making the detector pixel size less then 50{mu}m. The light emission from the CsI(Tl) is collimated by techniques involving the deposition process on pattered substrates. We have measured MTF of greater than 12 line pairs per mm at the 10% level.

Jing, T.; Cho, G. [Lawrence Berkeley Lab., CA (United States); Goodman, C.A. [Air Techniques, Inc., Hicksville, NY (United States)] [and others

1993-11-01T23:59:59.000Z

123

Amorphous silicon pixel layers with cesium iodide converters for medical radiography  

Science Conference Proceedings (OSTI)

The authors describe the properties of evaporated layers of Cesium Iodide (Thallium activated) deposited on substrates that enable easy coupling to amorphous silicon pixel arrays. The CsI (T1) layers range in thickness from 65 to 220[mu]m. The authors used the two-boat evaporator system to deposit CsI(T1) layers. This system ensures the formation of the scintillator film with homogeneous thallium concentration which is essential for optimizing the scintillation light emission efficiency. The Tl concentration was kept to 0.1--0.2 mole percent for the highest light output. Temperature annealing can affect the microstructure as well as light output of the CsI(T1) film. 200--300 C temperature annealing can increase the light output by a factor of two. The amorphous silicon pixel arrays are p-i-n diodes approximately 1[mu]m thick with transparent electrodes to enable them to detect the scintillation light produced by X-rays incident on the CsI(T1). Digital radiography requires a good spatial resolution. This is accomplished by making the detector pixel size less than 50 [mu]m. The light emission from the CsI(T1) is collimated by techniques involving the deposition process on patterned substrates. The authors have measured MTF of greater than 12 line pairs per mm at the 10% level.

Jing, T.; Drewery, J. (Lawrence Berkeley Lab., CA (United States)); Goodman, C.A. (Air Techniques, Inc., Hicksville, NY (United States))

1994-08-01T23:59:59.000Z

124

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

DOE Patents (OSTI)

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.

Carlson, David E. (Yardley, PA)

1980-01-01T23:59:59.000Z

125

Research on high-band-gap materials and amorphous-silicon-based solar cells. Annual subcontract report, May 15, 1994--May 14, 1995  

DOE Green Energy (OSTI)

We have conducted a survey of thin BP:H and BPC:H films prepared by plasma deposition using phosphine, diborane, tri-methylboron, and hydrogen as precursor gases. The objective of this research is to find out whether such films might offer a superior window layer film for application to wide bandgap a-Si solar cells. The research has shown good optical properties in a-BP:H films, but electrical properties acceptable for use in window layers have not been demonstrated yet. We have also found an interesting, conductive and transparent BPC:H film in a remote deposition region of the reactor, but have been unable to transfer deposition of this film to the standard interelectrode region. We have developed our capability to deposit nip sequence amorphous silicon based solar cells, and have demonstrated an open circuit voltage greater than 0.7 V. We have continued our studies of built-in potentials in a-Si based solar cells using the electroabsorption technique, extending our measurements to include cells with wider bandgap intrinsic layers and Schottky barrier test structures. We have made the first time-of-flight drift mobility measurements on a-Si:H prepared by hot wire (HW) deposition. Initial work has shown that light-soaked HW material can have much better ambipolar diffusion lengths than the plasma-deposited material following extended light soaking. We have performed some theoretical work which addresses a difficulty in understanding photocarrier recombination in a-Si:H first identified by Marvin Silver. In particular, electron-hole recombination is much slower than expected from the well-known {open_quotes}diffusion-controlled{close_quotes} models for Onsager (geminate) recombination and Langevin recombination. This slowness is essential to the success of a-Si in solar cells, but is unexplained. We have done work on high field electron drift mobilities in a-Si:H and on the validity of the Einstein relation connecting the diffusion and drift of holes in a-Si:H.

Schiff, E.A.; Gu, Q.; Jiang, L.; Wang, Q. [Syracuse Univ., NY (United States)

1995-12-01T23:59:59.000Z

126

Measurment of Depositing and Bombarding Species Involved in the Plasma Production of Amorphous Silicon and Silicon/Germanium Solar Cells: Annual Technical Report, 1 June 2002 - 31 May 2005  

DOE Green Energy (OSTI)

The objective of this study is to measure the molecular species that lead to the growth of hydrogenated amorphous silicon (a-Si:H) and microcrystalline silicon (..mu..c-Si) photovoltaic (PV) devices from RF discharges. Neutral radicals produce most of the film growth during this PV-device production, and, by implication, radicals primarily determine the device structure and electrical characteristics. The most important feature of the present experiment is thus the measurement of neutral-radical fluxes to the substrate. Additional depositing species that can influence film properties are positive ions and silicon-based particles produced by the discharge; we also measure these positive-ion species here. Some studies have already measured some of these radical and positive-ion species in silane and silane/argon discharges, but not for discharge conditions similar to those used to produce most photovoltaic devices. Our objective is to measure all of these species for conditions typically used for device production. In particular, we have studied 13.6 MHz-excited discharges in pure silane and silane/hydrogen vapors.

Gallagher, A.; Rozsa, K.; Horvath, P.; Kujundcik, D.

2006-06-01T23:59:59.000Z

127

Characterization of amorphous silicon thin films and PV devices: Phase 1 annual technical report: January 1998--January 1999  

DOE Green Energy (OSTI)

Major accomplishments of the previous year include: (1) an evaluation of the potential for n-type doping of a-SiS{sub x}:H and a-SiSe{sub x}:H alloys, (2) an investigation of the optically induced metastabilities in a-SiS{sub x}:H and a-SiSe{sub x}:H alloys with regard to their potential use in photovoltaic applications, and (3) a more detailed understanding of the kinetics of light-induced electron spin resonance (ESR) due to carriers trapped in localized band-tail states in a-Si:H. Also of importance are preliminary measurements of the defects and metastabilities in hot-wire samples of a-Si:H and in samples of a-Si:H made under strong hydrogen dilution. The preliminary measurements on hydrogen dilution suggest that the production of neutral silicon dangling bonds is not suppressed from the standard material even though there appears to be an improvement in the stability of cells made using the hydrogen-dilution process. The new three-chamber, load-locked plasma-enhanced chemical vapor deposition system is functioning and producing intrinsic and doped films of a-Si:H. Plans for the next year include the production of high quality devices using this new deposition system.

Taylor, P.C.

1999-10-27T23:59:59.000Z

128

Low-band-gap, amorphous-silicon-based alloys by chemical vapor deposition: Annual subcontract report, 1 October 1985-31 January 1986  

DOE Green Energy (OSTI)

This research was conducted to determine the potential of photochemical vapor deposition (photo-CVD) for producing high-quality, low-band-gap amorphous silicon germanium alloys for use in high-efficiency, multijunction, thin-film photovoltaic solar cells. A photo-CVD reactor for mercury-sensitized photolysis of silane-germane and disilane-germane mixtures was developed. Alloy thin films of undoped a-Si/sub 1-x/Ge/sub x/:H were deposited using mercury vapor mixed with SiH/sub 4/ or Si/sub 2/H/sub 6/, GeH/sub 4/, and diluent gas of Ar, He, or H/sub 2/. Materials properties were characterized by measurements of Ge content, optical transmission and reflection, and dark and photo-conductivity. Opto-electronic properties of photo-CVD a-Si/sub 1-x/Ge/sub x/:H were found to be comparable to glow discharge and sputtered materials. Moreover, p-i-n solar cells with low-band-gap i-layers were able to be fabricated by photo-CVD.

Baron, B.N.; Jackson, S.C.

1986-12-01T23:59:59.000Z

129

Photoluminescence study of the structural evolution of amorphous and crystalline silicon nanoclusters during the thermal annealing of silicon suboxide films with different stoichiometry  

SciTech Connect

The effect of the stoichiometry of thin silicon suboxide films on the processes of the formation and evolution of silicon nanoclusters during thermal annealing is studied by photoluminescence measurements. The samples are produced by the thermal sputtering of a SiO powder in an oxygen atmosphere, with the subsequent deposition of a 500 nm-thick SiO{sub x} layer onto a Si substrate. The morphological properties and size of Si nanoclusters are explored by analyzing the photoluminescence spectra and kinetics. A comparative study of the luminescence properties of thin SiO{sub x} layers with different stoichiometric parameters, x = 1.10, 1.29, 1.56, and 1.68, is accomplished for samples annealed at different temperatures in the range 850 to 1200 Degree-Sign C. The dependences of the photoluminescence decay time on the annealing temperature, the stoichiometric parameter of the initial silicon suboxide film, and the nanocluster size are studied.

Zhigunov, D. M., E-mail: dmzhigunov@physics.msu.ru; Shvydun, N. V.; Emelyanov, A. V.; Timoshenko, V. Yu.; Kashkarov, P. K. [Lomonosov Moscow State University, Physics Department (Russian Federation); Seminogov, V. N. [Russian Academy of Sciences, Institute of Laser and Information Technologies (Russian Federation)

2012-03-15T23:59:59.000Z

130

Atomic-scale characterization of hydrogenated amorphous-silicon films and devices. Annual subcontract report, 14 February 1995--14 April 1996  

DOE Green Energy (OSTI)

The research is concerned with improving the electronic properties of hydrogenated amorphous silicon (a-Si:H) films and of photovoltaic (PV) cells that use these films. Two approaches toward this goal are being taken. One is to establish the character of silicon particle growth in the rf glow discharges that are used to make the films and PV cells, and to understand the particle incorporation into the films. The ultimate goal of this effort is to find mitigation techniques that minimize the particle incorporation. During this contract period, the authors have developed a novel particle light-scattering technique that provides a very detailed and sensitive diagnostic of the particles suspended in the discharge. The second program is directed toward measuring the electronic properties of these thin-film PV cells, as a function of depth within the cell. The approach being taken is to use a scanning tunneling microscope (STM) to measure the depth-dependent electronic properties of cross-sectioned PV cells. During the present period, cell cleaving and cross section locating methods, both in a UHV environment, have been successfully developed.

Gallagher, A.; Barzen, S.; Childs, M.; Laracuente, A. [National Inst. of Standards and Technology, Boulder, CO (United States)

1997-02-01T23:59:59.000Z

131

Research on high-efficiency, single-junction, monolithic, thin-film amorphous silicon solar cells: Annual subcontract report, May 1985 - Jul 1986  

DOE Green Energy (OSTI)

A study was undertaken of the optoelectronic properties of amorphous silicon-hydrogen thin films deposited from disilane at high deposition rates. The information derived from this study was used to fabricate amorphous silicon solar cells with efficiencies exceeding 7%. The intrinsic layer of these solar cells was deposited at 15 angstroms/second. Material properties investigated included dark conductivity, photoconductivity, minority carrier diffusion length, and density of states. The solar cells properties characterized were absolute quantum yield and simulated global AM 1.5 efficiencies. Investigations were undertaken utilizing optical and infrared spectroscopy to optimize the microstructures of the intrinsic amorphous silicon. That work was sponsored by the New York State Energy Research and Development Authority. The information was used to optimize the intrinsic layer of amorphous silicon solar cells, resulting in AM 1.5 efficiencies exceeding 7%.

Wiesmann, H.; Dolan, J.; Fricano, G.; Danginis, V.

1987-02-01T23:59:59.000Z

132

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

DOE Patents (OSTI)

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.

Moustakas, Theodore D. (Annandale, NJ); Maruska, H. Paul (Annandale, NJ)

1985-07-09T23:59:59.000Z

133

Photochemical vapor deposition of amorphous silicon photovoltaic devices. Semiannual subcontract report, 1 May 1985-31 October 1985  

DOE Green Energy (OSTI)

Intrinsic, p-type, and n-type hydrogenated amorphous silicon thin-films have been deposited by mercury-sensitized photochemical vapor deposition (photo-CVD) from disilane. The photochemical reactor design includes two chambers separated by a movable uv-transparent Teflon curtain to eliminate deposition on the reactor window. Glass/TCO/p-i-n/metal photovoltaic devices were fabricated by photo-CVD. The efficiency at 87.5 MW/cm/sup 2/(ELH) was 5.1%.

Baron, B.N.; Rocheleau, R.E.; Hegedus, S.S.

1986-06-01T23:59:59.000Z

134

Gas-phase free radical reactions in the glow-discharge deposition of hydrogenated amorphous silicon from silane and disilane  

SciTech Connect

An analysis of a measurement by Matsuda and co-workers of the lifetimes of the free radicals involved in the glow-discharge deposition of amorphous hydrogenated silicon from silane and disilane at 20-mTorr pressure is consistent with the hypothesis that SiH or SiH/sub 2/, but not SiH/sub 3/, is the dominant radical in the deposition from silane at that pressure.

Kampas, F.J.

1985-03-15T23:59:59.000Z

135

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

SciTech Connect

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.

Wang, Qi; Crandall, R.S. [National Renewable Energy Lab., Golden, CO (United States); Schiff, E.A. [Syracuse Univ., NY (United States)

1996-05-01T23:59:59.000Z

136

Studies on relative effects of charged and neutral defects in hydrogenated amorphous silicon  

DOE Green Energy (OSTI)

This report covers the third year of a continuing research study to understand the relative importance of charged and neutral defects in amorphous silicon. The objective of the study is to explore the electronic structure, including neutral and charged defects, an optoelectronic effects including the formation of Staebler-Wronski defects. The study concentrated on exploring electroluminescence experimentally and interpreting the results employing a simple guiding model. The simple guiding model assumes an exponential density of states and recombination rate constants (radiative and non-radiative) which are governed by hopping transitions. Measurements were also made as a function of photodegradation of the material. The results implicate that the radiative recombination processes are not distant pair tunneling but rather results from electrons hopping down due to the coulomb interactions. Preliminary experiments have been made on the effect of photodegradation on transient space charge limited currents in n/i/n structures. These experiments can directly yield information on the occupied defects centers induced by the photodegradation and are not a result of recombination processes. To date the results seems to be consistent with a picture which places the doubly occupied defects at quite a high energy ({approx equal} 0.4 e.v. below the conduction band).

Silver, M. (North Carolina Univ., Chapel Hill, NC (United States))

1992-02-01T23:59:59.000Z

137

Optimization of transparent and reflecting electrodes for amorphous-silicon solar cells. Final subcontract report, 1 May 1991--30 April 1994  

DOE Green Energy (OSTI)

Fluorine-doped zinc oxide was shown to have the lowest absorption loss of any of the known transparent conductors. An apparatus was constructed to deposit textured, transparent, conductive, fluorine-doped zinc oxide layers with uniform thickness over a 10 cm by 10 cm area, using inexpensive, high-productivity atmospheric pressure chemical vapor deposition. Amorphous silicon solar cells grown on these textured films show very high peak quantum efficiencies (over 90%). However, a significant contact resistance develops at the interface between the amorphous silicon and the zinc oxide. Transparent, conductive gallium-doped zinc oxide films were grown by APCVD at a low enough temperature (260{degree}C) to be deposited on amorphous silicon as a final conductive back contact to solar cells. A quantum-mechanical theory of bonding was developed and applied to some metal oxides; it forms a basis for understanding TCO structures and the stability of their interfaces with silicon.

Gordon, R.G.; Hu, J.; Lacks, D.; Musher, J.; Thornton, J.; Liang, H. [Harvard Univ., Cambridge, MA (United States)

1994-07-01T23:59:59.000Z

138

Low-band-gap, amorphous-silicon-based alloys by photochemical vapor deposition: Final report, 1 October 1985--30 November 1986  

DOE Green Energy (OSTI)

Thin films of hydrogenated amorphous silicon-germanium alloys were deposited by mercury-sensitized photochemical vapor deposition using a novel photo-CVD reactor. Thin films of a-Si/sub 1-x/Ge/sub x/:H with 0 less than or equal to x less than or equal to 1 and 1.0 less than E/sub g/ less than 1.8 eV were deposited from mixtures of silane and disilane with germane and inert gas diluents at substrate temperatures from 160/degree/ to 200/degree/C. Alloy films were characterized by measurements of photo- and dark conductivity, electron mobility-lifetime product, sub-band-gap absorption, and density of states. Dilution with hydrogen increased the photoconductivity to 10/sup /minus/5/ Scm and mobility-lifetime product to 6 /times/ 10/sup /minus/8/ cm/sup 2/V for alloys having a band gap of 1.4 eV.

Baron, B.N.; Hegedus, S.S.; Jackson, S.C.

1988-02-01T23:59:59.000Z

139

Studies of pure and nitrogen-incorporated hydrogenated amorphous carbon thin films and their possible application for amorphous silicon solar cells  

Science Conference Proceedings (OSTI)

Hydrogenated amorphous carbon (a-C:H) and nitrogen-incorporated a-C:H (a-C:N:H) thin films were deposited using radio frequency-plasma-enhanced chemical vapor deposition technique and studied for their electrical, optical, and nano-mechanical properties. Introduction of nitrogen and increase of self bias enhanced the conductivity of a-C:H and a-C:N:H films, whereas current-voltage measurement reveals heterojunction formation due to their rectifying behavior. The bandgap of these films was changed over wide range from 1.9 eV to 3.45 eV by varying self bias and the nitrogen incorporation. Further, activation energy was correlated with the electronic structure of a-C:H and a-C:N:H films, and conductivity was discussed as a function of bandgap. Moreover, a-C:N:H films exhibited high hardness and elastic modulus, with maximum values as 42 GPa and 430 GPa, respectively, at -100 V. Observed fascinating electrical, optical, and nano-mechanical properties made it a material of great utility in the development of optoelectronic devices, such as solar cells. In addition, we also performed simulation study for an a-Si:H solar cell, considering a-C:H and C:N:H as window layers, and compared their performance with the a-Si:H solar cell having a-SiC:H as window layer. We also proposed several structures for the development of a near full-spectrum solar cell. Moreover, due to high hardness, a-C:N:H films can be used as a protective and encapsulate layer on solar cells, especially in n-i-p configuration on metal substrate. Nevertheless, a-C:H and a-C:N:H as a window layer can avoid the use of additional hard and protective coating and, hence, minimize the cost of the product.

Dwivedi, Neeraj [Physics of Energy Harvesting Division, National Physical Laboratory (CSIR), K.S. Krishnan Road, New Delhi 110012 (India); Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Kumar, Sushil [Physics of Energy Harvesting Division, National Physical Laboratory (CSIR), K.S. Krishnan Road, New Delhi 110012 (India); Malik, Hitendra K. [Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India)

2012-01-01T23:59:59.000Z

140

High performance hydrogenated amorphous silicon solar cells made at a high deposition rate by glow discharge of disilane  

SciTech Connect

The deposition rate, electronic and optical properties of hydrogenated amorphous silicon films prepared from rf glow discharge decomposition of disilane (Si/sub 2/H/sub 6/) diluted in helium have been measured. These films show excellent electrical and optical properties and, most importantly, a high deposition rate coupled with satisfactory solar cell application was realized for the first time. At a deposition rate of 11 A/s, 5.47% and 6.5% conversion efficiencies were obtained with a first trial of n-i-p type solar cells deposited on SnO/sub 2//ITO glass and metal substrates, respectively.

Ohashi, Y.; Kenne, J.; Konagai, M.; Takahashi, K.

1983-06-15T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

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

DOE Green Energy (OSTI)

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.

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

2008-05-01T23:59:59.000Z

142

THE USE OF AMORPHOUS SILICON IN FABRICATING A PHOTOVOLTAIC-THERMAL SYSTEM  

E-Print Network (OSTI)

& irradiation intensity 1 INTRODUCTION With the high increase in PV system production and solar energy use this information and solar irradiation data [4], electricity production during the entire lifetime of the PV system grade silicon Multicrystalline silicon ingot Multicrystalline silicon wafer Solar cell PV module PV

Kherani, Nazir P.

143

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

DOE Green Energy (OSTI)

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.

Deng, X.; Izu, M.; Jones, S.J.; Kopf, R. [Energy Conversion Devices, Troy, MI (United States)] [and others

1997-04-01T23:59:59.000Z

144

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

DOE Green Energy (OSTI)

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.

Sopori, B.

2012-09-01T23:59:59.000Z

145

Lithium implantation at low temperature in silicon for sharp buried amorphous layer formation and defect engineering  

SciTech Connect

The crystalline-to-amorphous transformation induced by lithium ion implantation at low temperature has been investigated. The resulting damage structure and its thermal evolution have been studied by a combination of Rutherford backscattering spectroscopy channelling (RBS/C) and cross sectional transmission electron microscopy (XTEM). Lithium low-fluence implantation at liquid nitrogen temperature is shown to produce a three layers structure: an amorphous layer surrounded by two highly damaged layers. A thermal treatment at 400 Degree-Sign C leads to the formation of a sharp amorphous/crystalline interfacial transition and defect annihilation of the front heavily damaged layer. After 600 Degree-Sign C annealing, complete recrystallization takes place and no extended defects are left. Anomalous recrystallization rate is observed with different motion velocities of the a/c interfaces and is ascribed to lithium acting as a surfactant. Moreover, the sharp buried amorphous layer is shown to be an efficient sink for interstitials impeding interstitial supersaturation and {l_brace}311{r_brace} defect formation in case of subsequent neon implantation. This study shows that lithium implantation at liquid nitrogen temperature can be suitable to form a sharp buried amorphous layer with a well-defined crystalline front layer, thus having potential applications for defects engineering in the improvement of post-implantation layers quality and for shallow junction formation.

Oliviero, E. [CSNSM, CNRS-IN2P3-Universite Paris-Sud, Batiment 108, 91405 Orsay (France); David, M. L.; Beaufort, M. F.; Barbot, J. F. [Institut Pprime, CNRS-Universite de Poitiers-ENSMA, SP2MI, Bd Marie et Pierre Curie, BP30179, 86962 Futuroscope-Chasseneuil Cedex (France); Fichtner, P. F. P. [Departamento de Metalurgia, Universidade Federal do Rio Grande do Sul, Av Bento Goncalves 9500, Caixa Postal 15051, 90035-190 Porto Alegre, RS (Brazil)

2013-02-28T23:59:59.000Z

146

Research on high-efficiency, single-junction, monolithic, thin-film amorphous silicon solar cells  

DOE Green Energy (OSTI)

This document describes the progress made in obtaining stable, a-Si-based submodules that have a large area and high efficiency. Conversion efficiencies of up to 11.95% were obtained in small-area, single-junction a-Si solar cells using textured TiO{sub 2}, superlattice p-layers, graded carbon concentrations near the p/i interface, and highly reflective ITO/silver back contacts. Single- junction a-SiC and a-SiGe p-i-n cells were also fabricated that had conversion efficiencies of 9%--11%, and some recently fabricated stacked-junction cells had conversion efficiencies of about 10%. In materials research boron-doped microcrystalline SiC films were recently developed containing up to 6 at. % carbon with conductivities of 3 {times} 10{sup {minus}3}/{Omega}-cm at room temperature and activation energies of 0.11 eV. Microcrystalline film growth was shown to be strongly influenced by the nature of the substrate, with nucleation occurring more readily on a-Si substrates than on TiO{sub 2}. Stability studies show that light-induced degradation is usually enhanced by the presence of carbon grading near the p/i interface. In general, adding either germanium (from GeH{sub 4}) or carbon (from CH{sub 4}) to the i-layer of a p-i-n cell leads to enhanced light-induced degradation. 13 refs., 80 figs., 17 tabs.

Catalano, A.W.; Carlson, D.E.; Ayra, R.R.; Bennett, M.S.; D'Aiello, R.V.; Dickson, C.R.; Fortmann, C.M.; Goldstein, B.; McVeigh, J.; Morris, J.; Newton, J.L.; Wiedeman, S. (Solarex Corp., Newtown, PA (USA). Thin Film Div.)

1989-10-01T23:59:59.000Z

147

High-rate deposition of hydrogenated amorphous silicon films and devices  

SciTech Connect

In high-rate deposition of a-Si:H films, the effect of deposition parameters on material properties are examined when silane and disilane are the feed gases. The emphasis is on RF glow discharge, but other deposition methods are also covered. The problems of gas-phase polymerization and power formation at high rates have been overcome by modified reactor designs. Deposition rates of 1-3 nm/s are adequate for economically fabricating the intrinsic layer. Laboratory-size a-Si:H cells with greater than 10% efficiency have been achieved with both silane and disilane at rates in the 1- to 2-nm/s range.

Luft, W.

1988-12-01T23:59:59.000Z

148

Technical evaluation of a dual-junction same-band-gap amorphous silicon photovoltaic system at NREL  

DOE Green Energy (OSTI)

On December 7, 1992, a 1.8-kW{sub ac} utility-interconnect photovoltaic (PV) system using amorphous silicon modules was brought on-line at the National Renewable Energy Laboratory`s photovoltaic test site. This system was deployed to conduct an in-situ technical evaluation of the PV array (in a high voltage configuration) and system performance and reliability in a utility-interconnect application. The system is unique due to the installation of construction-grade insulation on the back of each PV module. This use of insulation is an attempt to levelize the annual array power output by elevating the operating temperature of the modules. This paper presents array and system performance data. Emphasis is placed on quantifying the effects of individual losses as well as seasonal changes on PV array and system performance.

Strand, T.; Mrig, L.; Hansen, R.; Emery, K.

1994-12-01T23:59:59.000Z

149

Amorphous silicon solar cells. Quarterly report No. 1, 1 October 1980-31 December 1980  

DOE Green Energy (OSTI)

Progress is reported on the following: theoretical modeling, deposition and doping studies, experimental methods for the characterization of a-Si:H, formation of solar-cell structures, theoretical and experimental evaluation of solar-cell parameters, and stability studies. (MHR)

Carlson, D.E.; Balberg, I.; Crandall, R.S.; Dresner, J.; Goldstein, B.; Hanak, J.J.; Schade, H.E.; Staebler, D.L.; Weakliem, H.A.

1981-02-01T23:59:59.000Z

150

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

DOE Green Energy (OSTI)

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.

Guha, S.; Yang, J.

2007-07-01T23:59:59.000Z

151

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

DOE Patents (OSTI)

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.

Mahan, Archie Harvin (Golden, CO); Molenbroek, Edith C. (Rotterdam, NL); Gallagher, Alan C. (Louisville, CO); Nelson, Brent P. (Golden, CO); Iwaniczko, Eugene (Lafayette, CO); Xu, Yueqin (Golden, CO)

2002-01-01T23:59:59.000Z

152

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

DOE Green Energy (OSTI)

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.

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.

2010-04-30T23:59:59.000Z

153

Transport, Interfaces, and Modeling in Amorphous Silicon Based Solar Cells: Final Technical Report, 11 February 2002 - 30 September 2006  

DOE Green Energy (OSTI)

Results for a-Si characteristics/modeling; photocarrier drift mobilities in a-Si;H, ..mu..c-Si:H, CIGS; hole-conducting polymers as p-layer for a-Si and c-Si; IR spectra of p/i and n/i interfaces in a-Si.

Schiff, E. A.

2008-10-01T23:59:59.000Z

154

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

SciTech Connect

Air Products set out to investigate the impact of additives on the deposition rate of both ???µCSi and ???±Si-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.

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

2012-08-31T23:59:59.000Z

155

Study of plasma enhanced chemical vapor deposition of boron-doped hydrogenated amorphous silicon thin films and the application to p-channel thin film transistor  

E-Print Network (OSTI)

The material and process characteristics of boron doped hydrogenated amorphous silicon (a-Si:H) thin film deposited by plasma enhanced chemical vapor deposition technique (PECVD) have been studied. The goal is to apply the high quality films deposited at low substrate temperature for devices such as thin film transistors (TFTs). The effect of the deposition parameters such as doping gas concentration, substrate temperature, hydrogen dilution, helium dilution, power density, and pressure at 50 kHz rf frequency on the films' characteristics were analyzed. The films' electrical property was characterized by its dark resistivity. The chemical composition and bonding characteristics were discussed. p-channel TFTs were fabricated with these optimized films. Three different levels of dopant concentrations in the channel were used to detect the dopant effect on the TFT properties. Doping resulted in the increase of film deposition rate. The low film deposition rate at the high temperature deposition corresponds to a dense structured film. The increase of gas phase H? concentration could increase H? etching of the weak bonds in the film, which is consistent with the decrease of the deposition rate. Film's dark conductivity is determined by the atomic B concentration in the film, the substrate temperature, the ion bombardment effect, the surface morphology, and the gas phase and film hydrogen concentration. At high power density and high pressure plasma condition, film with a high deposition rate shows a high conductivity. However, excessive ion bombardment effect, e.g. in powdery plasma region, limits the further increase of the conductivity. Film deposited with He dilution demonstrates a higher conductivity compared to the H? dilution counterpart. This might be attributed to a more effective ion bombardment effect of the former. Powder generation in the plasma significantly affects the conductivity of He diluted film compared to the H? diluted ones, which might be due to the less H? etching effect at the He dilution deposition. The output and transfer characteristics show the normal p-channel TFTs behavior. TFT characteristics, such as mobility, threshold voltage, and on-off current ratio were affected by the doping gas concentration in the channel layer and the deposition process.

Nominanda, Helinda

2004-01-01T23:59:59.000Z

156

Abnormal humidity-dependent electrical properties of amorphous carbon/silicon heterojunctions  

Science Conference Proceedings (OSTI)

Amorphous carbon (a-C) film/n-Si heterojunctions have been fabricated by pulse laser deposition, and their current-voltage characteristics have been investigated. The results show that the atmosphere relative humidity (RH) has a significant effect on the reverse bias I-V characteristics of the heterojunctions. For the low bias voltages, the resistance of the a-C/Si heterojunction decreases with the increase of the RH. However, when the applied voltage is greater than a threshold, the resistance of the a-C/Si heterojunctions increases with the increase of the RH. This humidity-dependent phenomenon is attributed to the charge transfer from the absorbed H{sub 2}O molecular to a-C film.

Gao Xili; Zhang Xiaozhong; Wan Caihua; Zhang Xin; Wu Lihua; Tan Xinyu [Department of Materials Science and Engineering, Laboratory of Advanced Materials, Tsinghua University, Beijing 100084 (China) and National Center for Electron Microscopy (Beijing), Tsinghua University, Beijing 100084 (China)

2010-11-22T23:59:59.000Z

157

Research on the structural and electronic properties of defects in amorphous silicon  

DOE Green Energy (OSTI)

The work performed for this contract focused on the saturation of light-induced effects, hydrogen-mediated metastability and growth, defects and electronic properties, and remote hydrogen plasma growth. This work included research on hydrogen chemical reactions, hydrogen density-of-states model and metastability, hydrogen bonding configurations, a model for the role of hydrogen complexes in the metastability, and hydrogen chemical potential and growth structure. This document also covers research on thermal generation currents in p-i-n diodes, field dependence of the generation current, metastability effects at contacts, and potential fluctuations in compensated a-Si:H. Information is included on plasma diagnostics using electron spin resonance and nuclear magnetic resonance measurements of remote hydrogen plasma films.

Street, R.A. (Xerox Palo Alto Research Center, CA (United States))

1991-12-01T23:59:59.000Z

158

Research on stable, high-efficiency amorphous silicon multijunction modules. Semiannual subcontract report, 1 January 1990--30 June 1991  

DOE Green Energy (OSTI)

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.

Guha, S. [United Solar Systems Corp., Troy, MI (United States)

1991-12-01T23:59:59.000Z

159

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

DOE Green Energy (OSTI)

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.

Izu, M. [Energy Conversion Devices, Inc., Troy, MI (United States)] [Energy Conversion Devices, Inc., Troy, MI (United States)

1994-06-01T23:59:59.000Z

160

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

DOE Green Energy (OSTI)

This report describes the progress made during Phase 1 of research and development program to obtain high-efficiency amorphous silicon alloy multijunction modules. Using a large-area deposition system, double-and triple-junction cells were made on stainless steel substrates of over 1 ft{sup 2} area with Ag and ZnO predeposited back reflector. Modules of over 1 ft{sup 2} were produced with between 9.2% and 9.9 initial aperture-area efficiencies as measured under a USSC Spire solar simulator. Efficiencies as measured under the NREL Spire solar simulator were found to be typically 15% to 18% lower. The causes for this discrepancy are now being investigated. The modules show about 15% degradation after 600 hours of one-sun illumination at 50{degrees}C. To optimize devices for higher stabilized efficiency, a new method was developed by which the performance of single-junction cells after long-term, one-sun exposure at 50{degrees}C can be predicted by exposing cells to short-term intense light at different temperatures. This method is being used to optimize the component cells of the multijunction structure to obtain the highest light-degraded efficiency.

Banerjee, A.; Chen, E.; Clough, R.; Glatfelter, T.; Guha, S.; Hammond, G.; Hopson, M.; Jackett, N.; Lycette, M.; Noch, J.; Palmer, T.; Pawlikiewicz, A.; Rosenstein, I.; Ross, R.; Wolf, D.; Xu, X.; Yang, J.; Younan, K.

1992-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Amorphous silicon as electron transport layer for colloidal semiconductor nanocrystals light emitting diode  

Science Conference Proceedings (OSTI)

We demonstrate the fabrication of light-emitting diodes (LEDs) made from all-inorganic colloidal semiconducting nanocrystals (NCs). The diode utilizes a sandwich structure formed by placing CdSe/CdS NCs between two layers of Si and Ag{sub x}O, which act as electron- and hole-transporting materials, respectively. The photoluminescence properties of NCs are rendered less dependent upon surface chemistry and chemical environment by growing a thick CdS shell. It also enhances stability of the NCs during the process of magnetron sputtering for silicon deposition. The resulting LED device exhibits a low turn-on voltage of 2.5 V and the maximum external quantum efficiency of nearly 0.08%.

Song Tao; Shen Xiaojuan; Sun Baoquan [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Functional Nano and Soft Materials Laboratory (FUNSOM), Soochow University, 199 Ren'ai Road, Suzhou 215123 (China); Zhang Fute [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Functional Nano and Soft Materials Laboratory (FUNSOM), Soochow University, 199 Ren'ai Road, Suzhou 215123 (China); Key Laboratory of Organic Synthesis of Jiangsu Province, School of Chemistry and Chemical Engineering, Soochow University, Suzhou 215123 (China); Zhang Xiaohong [Nano-Organic Photoelectronic Laboratory and Laboratory of Organic Optoelectronic Functional Materials and Molecular Engineering, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Zhu Xiulin [Key Laboratory of Organic Synthesis of Jiangsu Province, School of Chemistry and Chemical Engineering, Soochow University, Suzhou 215123 (China)

2009-12-07T23:59:59.000Z

162

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

DOE Green Energy (OSTI)

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.

Guha, S.; Yang, J.

2008-05-01T23:59:59.000Z

163

Optimization of transparent and reflecting electrodes for amorphous silicon solar cells. Final technical report  

DOE Green Energy (OSTI)

Transparent conducting fluorine doped zinc oxide was deposited as thin films on soda lime glass substrates by atmospheric pressure chemical vapor deposition (CVD) at substrate temperatures of 460 to 500 degrees C. The precursors diethylzinc, tetramethylethylenediamine and benzoyl fluoride were dissolved in xylene. This solution was nebulized ultrasonically and then flash vaporized by a carrier gas of nitrogen preheated to 150 degrees C. Ethanol was vaporized separately, and these vapors were then mixed to form a homogeneous vapor mixture. Good reproducibility was achieved using this new CVD method. Uniform thicknesses were obtained by moving the heated glass substrates through the deposition zone. The best electrically and optical properties were obtained when the precursor solution was aged for more than a week before use. The films were polycrystalline and highly oriented with the c-axis perpendicular to the substrate. More than 90% of the incorporated fluorine atoms were electrically active as n-type dopants. The electrical resistivity of the films was as low as 5 x 10/sup -4/ Omega cm. The mobility was about 45 cm /Vs. The electron concentration was up to 3 x 10 %sup20;/cm. The optical absorption of the films was about 3-4% at a sheet resistance of 7 ohms/square. The diffuse transmittance was about 10% at a wavelength of 650 nm. Amorphous ilicon solar cells were deposited using the textured fluorine doped zinc oxide films as a front electrode. The short circuit current was increased over similar cells made with fluorine doped tin oxide, but the open circuit voltages and fill factors were reduced. The voltage was restored by overcoating the fluorine-doped zinc oxide with a thin layer of fluorine-doped tin oxide.

Gordon, R.G.; Kramer, K.; Liang, H.; Liu, X.; Pang, D.; Teff, D.

1998-09-01T23:59:59.000Z

164

Novel silane and disilane precursors to amorphous semiconductors: Final subcontract report, May 1988  

DOE Green Energy (OSTI)

This Final Report describes the preparation and characterization of amorphous fluorohydrogenated silicon thin films. The novel approach in this study lies in the use of fluorinated silanes as film precursors. The advantages of this method are well defined initial ratios of hydrogen and fluorine to silicon and greatly reduced hazards in the handling of the gas. Fluorine derivatives of both silane and disilane were synthesized. Both glow discharge (or plasma-enhanced CVD) and thermal (CVD) methods were employed to prepare amorphous silicon on glass and silicon wafers. The electrical characterization of the material prepared from difluorosilane showed that the a-Si:H:F films obtained are of solar-grade semiconductor quality and can be doped to p- and n-type materials with diborane and phosphine. 29 refs., 24 figs., 10 tabs.

Pernisz, U.C.; Sharp, K.G.

1988-09-01T23:59:59.000Z

165

Research on stable, high-efficiency, large-area amorphous silicon based modules -- Task B  

DOE Green Energy (OSTI)

This report documents progress in developing a stable, high- efficiency, four-terminal hybrid tandem module. The module consists of a semi-transparent, thin-film silicon:hydrogen alloy (TFS) top circuit and a copper indium diselenide (CuInSe{sub 2}) bottom circuit. Film deposition and patterning processes were successfully extended to 0.4-m{sup 2} substrates. A 33.2-W (8.4% efficient) module with a 3970-cm{sup 2} aperture area and a white back reflector was demonstrated; without the back reflector, the module produced 30.2 W (7.6% efficient). Placing a laminated, 31.6-W, 8.1%-efficient CuInSe{sub 2} module underneath this TFS module, with an air gap between the two, produces 11.2 W (2.9% efficient) over a 3883-cm{sup 2} aperture area. Therefore, the four-terminal tandem power output is 41.4 W, translating to a 10.5% aperture-area efficiency. Subsequently, a 37.8-W (9.7% aperture-area efficiency) CuInSe{sub 2} module was demonstrated with a 3905-cm{sup 2} aperture area. Future performances of single-junction and tandem modules of this size were modeled, and predicted power outputs exceed 50 W (13% efficient) for CuInSe{sub 2} and 65 W (17% efficient) for TFS/CuInSe{sub 2} tandem modules.

Mitchell, K.W.; Willet, D.R. (Siemens Solar Industries, Camarillo, CA (USA))

1990-10-01T23:59:59.000Z

166

Photovoltaic manufacturing technology monolithic amorphous silicon modules on continuous polymer substrates: Final technical report, July 5, 1995--December 31, 1999  

DOE Green Energy (OSTI)

Iowa Thin Film Technologies is completing a three-phase program that has increased throughput and decreased costs in nearly all aspects of its thin-film photovoltaic manufacturing process. The overall manufacturing costs have been reduced by 61 percent through implementation of the improvements developed under this program. Development of the ability to use a 1-mil substrate, rather than the standard 2-mil substrate, results in a 50 percent cost-saving for this material. Process development on a single-pass amorphous silicon deposition system has resulted in a 37 percent throughput improvement. A wide range of process and machine improvements have been implemented on the transparent conducting oxide deposition system. These include detailed parameter optimization of deposition temperatures, process gas flows, carrier gas flows, and web speeds. An overall process throughput improvement of 275 percent was achieved based on this work. The new alignment technique was developed for the laser scriber and printer systems, which improved registration accuracy from 100 microns to 10 microns. The new technique also reduced alignment time for these registration systems significantly. This resulted in a throughput increase of 75 percent on the scriber and 600 percent on the printer. Automated techniques were designed and implemented for the module assembly processes. These include automated busbar attachment, roll-based lamination, and automated die cutting of finished modules. These processes were previously done by hand labor. Throughput improvements ranged from 200 percent to 1200 percent, relative to hand labor rates. A wide range of potential encapsulation materials were evaluated for suitability in a roll lamination process and for cost-effectiveness. A combination material was found that has a cost that is only 10 percent of the standard EVA/Tefzel cost and is suitable for medium-lifetime applications. The 20-year lifetime applications still require the more expensive material.

Jeffrey, F.

2000-03-28T23:59:59.000Z

167

Performance and analysis of amorphous silicon p-i-n solar cells made by chemical-vapor deposition from disilane  

SciTech Connect

The photovoltaic performance of amorphous silicon p-i-n solar cells made by chemical-vapor deposition (CVD) from disilane is reported and analyzed. Intrinsic layers were deposited at rates from 0.2 to 50 A/s at temperatures from 380 to 460 /sup 0/C with and without boron doping. Device performance was insensitive to substantial differences in disilane purity. A cell efficiency of 4% was achieved. The primary limitation to higher efficiency was low fill factor (<50%) due to high series resistance (>18 ..cap omega.. cm/sup 2/). Analysis of the series resistance indicated a contact-related resistance of 4--12 ..cap omega.. cm/sup 2/ and a photoconductive resistance composed of intrinsic layer thickness-independent (10 ..cap omega.. cm/sup 2/) and thickness-dependent terms. Analysis of the voltage dependence of the current collection indicated a fill factor of 60% would be expected in the absence of series resistance. The maximum short-circuit current of 12.5 mA/cm/sup 2/ (normalized to 100 mW/cm/sup 2/) resulted with a boron-doped i layer deposited at 440 /sup 0/C at 3.3 A/s. Modeling of the collection efficiency indicated collection widths up to 0.33 ..mu..m for boron-doped and 0.24 ..mu..m for undoped p-i-n devices. In order to achieve high-efficiency cells using CVD from disilane, the limitations imposed by low photoconductivity, a high density of states, and restricted cell design imposed by the high deposition temperatures would have to be overcome.

Hegedus, S.S.; Rocheleau, R.E.; Buchanan, W.; Baron, B.N.

1987-01-01T23:59:59.000Z

168

Growth mechanisms and characterization of hydrogenated amorphous- silicon-alloy films. Annual subcontract report, 14 February 1991--13 February 1992  

SciTech Connect

This report describes an apparatus, constructed and tested, that allows measurement of the surface morphology of as-grown hydrogenated amorphous silicon films with atomic resolution using a scanning tunneling microscope. Surface topologies of 100-{degree}{Lambda}-thick intrinsic films, deposited on atomically flat, crystalline Si and GaAs, are reported. These films surfaces are relatively flat on the atomic scale, indicating fairly homogeneous, compact initial film growth. The effect of probe-tip size on the observed topology and the development of atomically sharp probes is discussed. 17 refs, 9 figs.

Gallagher, A.; Ostrom, R.: Stutzin, G.; Tanenbaum, D. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

1993-02-01T23:59:59.000Z

169

Growth mechanisms and characterization of hydrogenated amorphous-silicon-alloy films. Final subcontract report, 15 February 1991--14 April 1994  

SciTech Connect

This report describes work performed to better understand the atomic-scale structure of glow-discharge-produced a-Si:H, a-Ge:H, and a-Si:Ge:H films; its effect on film quality; and its dependence on deposition discharge conditions. Hydrogenated a-Si films are from a silane rf discharge onto atomically flat crystal Si and GaAs substrates. The substrates are then transferred in a scanning tunneling microscope, where the atomic-scale surface morphology is measured. The films were deposited using device-quality deposition conditions; IR absorption, {sigma}{sub L}, and {sigma}{sub D} indicate high-quality intrinsic films. From the thickness dependence of the surface morphology, we determined that the films initially conform smoothly to an atomically flat Si or GaAs substrate, but as the thickness increases the roughness steadily increases to approximately 10% of the length of the scanned region. The surface of 100--400-nm-thick films is highly inhomogeneous, with steep hills and canyons in some areas and large atomically smooth regions in others. These unexpectedly large surface irregularities indicate severe and often connected void structures in the growing film, as well as relatively limited-range surface diffusion of the incorporating SiH{sub 3} radicals. On the other hand, large atomically flat surface were occasionally found, indicating the possibility of growing a homogeneous and compact amorphous film if appropriate growth conditions could be discovered.

Gallagher, A.; Tanenbaum, D.; Laracuente, A.; Kalra, P. [National Inst. of Standards and Technology, Boulder, CO (United States)

1994-07-01T23:59:59.000Z

170

Dosimetric properties of an amorphous-silicon EPID used in continuous acquisition mode for application to dynamic and arc IMRT  

Science Conference Proceedings (OSTI)

Dosimetric properties of an amorphous-silicon electronic portal imaging device (EPID) operated in a real-time acquisition mode were investigated. This mode will be essential for time-resolved dose verification of dynamic (sliding window) intensity modulated radiation therapy (IMRT) and intensity modulated arc radiation therapy (arc-IMRT). The EPID was used in continuous acquisition mode (i.e., ''cine'' mode) where individual sequential image frames are acquired in real time. The properties studied include dose linearity, reproducibility of response, and image stability. Results of using the continuous acquisition mode with several example treatments including dynamic IMRT, arc treatment, and single-arc-IMRT are compared to results using the well-studied integrated acquisition mode (i.e., ''frame averaging'' or ''IMRT'' mode). Real-time EPID response was also compared to real-time ion-chamber data for selected points in the deliveries. The example treatment deliveries in both continuous and integrated acquisition modes were converted to arbitrary EPID dose units via a calibration field. The summation of all acquired continuous mode images was compared using percentage dose difference to the single image acquired in the integrated mode using in-field pixels only (defined as those pixels >10% of maximum, in-field signal). Using the continuous acquisition mode, the EPID response was not linear with dose. It was found that the continuous mode dose response corresponded approximately to dropping one image per acquisition session. Reproducibility of EPID response to low monitor units (MUs) was found to be poor but greatly improved with increasing MU. Open field profiles were found to be stable in the cross-plane direction but required several frames to become stable in the in-plane direction. However, both of these issues are clinically insignificant due to arc-IMRT deliveries requiring relatively large monitor units (>100 MU). Analysis of the five IMRT, arc, and arc-IMRT tests revealed that all examples compared to within 2% of maximum dose for more than 95% of in-field pixels. The continuous acquisition mode is suited to time-resolved dosimetry applications including arc-IMRT and dynamic IMRT, giving comparable dose results to the well-studied integrated acquisition mode, although caution should be used in low MU applications. Time-resolved EPID dose information also compared well to time-resolved ion-chamber measurements.

McCurdy, B. M. C.; Greer, P. B. [Division of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada) and Department of Radiology, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Newcastle, New South Wales 2298 (Australia) and School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, New South Wales 2308 (Australia)

2009-07-15T23:59:59.000Z

171

Fluorination of amorphous thin-film materials with xenon fluoride  

DOE Patents (OSTI)

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.

Weil, Raoul B. (Haifa, IL)

1988-01-01T23:59:59.000Z

172

Photovoltaic devices using a-Si:H from higher order silanes. Final subcontract report, September 1, 1983-August 31, 1984  

DOE Green Energy (OSTI)

This report describes the preparation of hydrogenated amorphous silicon (a-Si:H) films and photovoltaic devices by chemical vapor deposition (CVD) from higher silanes, and the properties of such films and devices. The motivation for this research is the prospect of preparing by a new technique a-Si:H having electronic properties similar (or superior) to material prepared by the well-known glow discharge technique. Possible advantages of thermal CVD are the absence of ion bombardment, high deposition rates, efficient utilization of feedstock gases, lower levels of impurity incorporation, absence of pinholes, and greater material stability. Photochemical vapor deposition of a-Si:H from disilane is also described and has yielded higher efficiency solar cells than thermal CVD.

Delahoy, A.E.

1985-03-01T23:59:59.000Z

173

Amorphous silicon technology  

SciTech Connect

The growth methods discussed in this volume include both regular and remote plasma enhanced chemical vapor deposition (PECVD), catalytic CVD (CTLCVD), atmospheric pressure CVD (APCVD), very high frequency plasma CVD (VHCVD) and magnetron sputtering. Some of the papers discuss the use of disilane to increase growth rates. The general questions of the kinetics of film growth is an important topic of discussion in this volume. Several mechanisms for monitoring film growth and lasma diagnostics are also topics of discussion.

Madan, A. (Glasstech Solar, Inc., Wheatridge, CO (USA)); Thompson, M.J. (Xerox Palo Alto Research Center, CA (USA)); Taylor, P.C. (Univ. of Utah, Salt Lake City, UT (US)); LeComber, P.G. (Univ. of Dundee, Dundee (GB)); Hamakawa, Y. (Osaka Univ., Osaka (JP))

1988-01-01T23:59:59.000Z

174

Junction Transport in Epitaxial Film Silicon Heterojunction Solar Cells: Preprint  

Science Conference Proceedings (OSTI)

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.

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

2011-07-01T23:59:59.000Z

175

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)

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.

Molenbroek, Edith C. (Utrecht, NL); Mahan, Archie Harvin (Golden, CO); Gallagher, Alan C. (Louisville, CO)

2000-09-26T23:59:59.000Z

176

Chemical vapor deposition of amorphous semiconductor films. Final subcontract report  

DOE Green Energy (OSTI)

Chemical vapor deposition (CVD) from higher order silanes has been studied for fabricating amorphous hydrogenated silicon thin-film solar cells. Intrinsic and doped a-Si:H films were deposited in a reduced-pressure, tubular-flow reactor, using disilane feed-gas. Conditions for depositing intrinsic films at growth rates up to 10 A/s were identified. Electrical and optical properties, including dark conductivity, photoconductivity, activation energy, optical absorption, band-gap and sub-band-gap absorption properties of CVD intrinsic material were characterized. Parameter space for depositing intrinsic and doped films, suitable for device analysis, was identified.

Rocheleau, R.E.

1984-12-01T23:59:59.000Z

177

Growth mechanisms and characterization of hydrogenated amorphous-silicon-alloy films. Annual subcontract report, 14 February 1992--13 February 1993  

SciTech Connect

This report describes work performed to better understand the atomic-scale structure of glow-discharge-produced a-Si:H, a Ge:H, and a-Si:Ge:H films; its effect on film quality; and its dependence on deposition discharge conditions. Hydrogenated a- Si films are deposited from a silane rf discharge onto atomically flat crystal Si and GaAs substrates. The substrates are then transferred in vacuum to a scanning tunneling microscope, where the atomic-scale surface morphology is measured. The films were deposited at T{sub s} = 30{degree}C and 250{degree}C from a silane rf glow discharge using device-quality deposition conditions of 2.66 Pa (0.5 Torr) silane pressure, 1.7 {Angstrom}/s deposition rate, and small power/flow; IR absorption, {sigma}{sub L}, and {sigma}{sub D} indicate high-quality intrinsic films. From the thickness dependence of the surface morphology, we determined that the films initially conform smoothly to an atomically flat Si or GaAs substrate, but as the thickness increases the roughness steadily increases to approximately 10% of the length of the scanned region. The surface of 100-400-nm-thick films is highly inhomogeneous, with steep hills and canyons in some areas and large atomically smooth regions in others. These unexpectedly large surface irregularities indicate severe and often connected void structures in the growing film, as well as relatively limited-range surface diffusion of the incorporating SiH{sub 3} radicals. On the other hand, large areas of atomically flat surface were occasionally found, indicating the possibility of growing a homogeneous and compact amorphous film if appropriate growth conditions could be discovered.

Gallagher, A.; Tanenbaum, D.; Laracuente, A.; Molenbroek, E. [National Inst. of Standards and Technology, Boulder, CO (United States)

1993-08-01T23:59:59.000Z

178

Photochemical vapor deposition of amorphous silicon photovoltaic devices: Annual subcontract report, 1 May 1985-30 April 1986  

DOE Green Energy (OSTI)

Intrinsic, p-type, and n-type a-Si:H and p-type a-SiC:H thin-films have been deposited by Hg-sensitized photochemical vapor depositions (photo-CVD) from disilane. The photochemical reactor design includes two chambers separated by a movable uv-transparent Teflon curtain, which eliminates deposition on the reactor window. Photovoltaic devices of the type glass/TCO/p-i-n/metal were fabricated by photo-CVD. The device efficiency obtained at 87.5 mW/cm/sup 2/ and ELH illumination was 6.4%.

Baron, B.N.; Rocheleau, R.E.; Hegedus, S.S.

1987-02-01T23:59:59.000Z

179

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

DOE Green Energy (OSTI)

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.

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

2008-05-01T23:59:59.000Z

180

HIGH EFFICIENCY AMORPHOUS SILICON GERMANIUM SOLAR CELLS X. Liao, W. Du, X. Yang, H. Povolny, X. Xiang and X. Deng  

E-Print Network (OSTI)

-layer/ ITO. The a-SiGe absorber i-layers were deposited using a gas mixture of disilane, germane and hydrogen with a varying germane to disilane ratio and a hydrogen dilution of 50-100. The illuminated I-V measurement

Deng, Xunming

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Research on stable, high efficiency amorphous silicon multijunction modules. Semiannual technical progress report, 1 May 1991--31 October 1991  

DOE Green Energy (OSTI)

Improvements towards a goal of a 12.5% initial triple-junction module efficiency require the use of a wide gap top-layer for improved open circuit voltage, higher transmission from the transparent front contact and more highly transmitting doped layers. To address the first issue, there has been continued development of a-SiC:H with the utilization of several novel feedstocks to control the atomic structure of the solid. These films have transport properties superior to the best results reported for a-SiC:H. Preliminary results with devices exhibits a stability comparable to a-Si:H, while previous results with a-SiC:H have generally shown for higher rates of degradation. Module fabrication has been refined to the extent that comparable module and small area device efficiencies are readily obtained. Despite the high initial efficiencies (9%--10%) obtained in 935 cm{sup 2} modules employing devices with 4000{Angstrom} thick middle junctions, higher than expected rates of degradation were found. The cause of the anomalous degradation was traced to shunts present in the device arising from defects in the tin oxide coating. NREL degradation results of triple-junction modules showed stabilized performance of the initial efficiency for modules prepared during the period in which shunts were a problem. 20 refs.

Catalano, A.; Arya, R.R.; Bennett, M.; Chen, L.; D`Aiello, R.; Fieselmann, B.; Li, Y.; Newton, J.; Podlesny, R.; Wiedeman, S.; Yang, L. [Solarex Corp., Newtown, PA (United States). Thin Film Div.

1992-02-01T23:59:59.000Z

182

Research on stable, high-efficiency, amorphous silicon multijunction modules. Annual subcontract report, 1 May 1991--30 April 1992  

DOE Green Energy (OSTI)

This report describes work to demonstrate a multijunction module with a ``stabilized`` efficiency (600 h, 50{degrees}C, AM1.5) of 10.5%. Triple-junction devices and modules using a-Si:H alloys with carbon and germanium were developed to meet program goals. ZnO was used to provide a high optical transmission front contact. Proof of concept was obtained for several important advances deemed to be important for obtaining high (12.5%) stabilized efficiency. They were (1) stable, high-quality a-SiC:H devices and (2) high-transmission, textured ZnO. Although these developments were not scaled up and included in modules, triple-junction module efficiencies as high as 10.85% were demonstrated. NREL measured 9.62% and 9.00% indoors and outdoors, respectively. The modules are expected to lose no more than 20% of their initial performance. 28 refs.

Catalano, A.; Bennett, M.; Chen, L.; D`Aiello, R.; Fieselmann, B.; Li, Y.; Newton, J.; Podlesny, R.; Yang, L. [Solarex Corp., Newtown, PA (United States). Thin Film Div.

1992-08-01T23:59:59.000Z

183

Development of high stable-efficiency, triple-junction a-Si alloy solar cells. Annual subcontract report, July 18, 1994--July 17, 1995  

DOE Green Energy (OSTI)

This report describes work performed by Energy Conversion Devices, Inc. (ECD) under a 3-year, cost-shared amorphous silicon (a-Si) research program to develop advanced technologies and to demonstrate stable 14%-efficient, triple-junction a-Si alloy solar cells. The technologies developed under the program will then be incorporated into ECD`s continuous roll-to-roll deposition process to further enhance ECD`s photovoltaic manufacturing technology. In ECD`s solar cell design, triple-junction a-Si alloy solar cells are deposited onto stainless-steel substrates coated with Ag/ZnO back-reflector layers. This type of cell design enabled ECD to use a continuous roll- to-roll deposition process to manufacture a-Si PV materials in high volume at low cost. Using this cell design, ECD previously achieved 13.7% initial solar cell efficiency using the following features: (1) a triple-junction, two-band-gap, spectrum-splitting solar cell design; (2) a microcrystalline silicon p-layer; (3) a band-gap-profiled a- SiGe alloy as the bottom cell i-layer; (4) a high-performance AgZnO back-reflector; and (5) a high-performance tunnel junction between component cells. ECD also applied the technology into its 2-MW/yr a- Si production line and achieved the manufacturing of 4-ft{sup 2} PV modules with 8% stable efficiency. During this program, ECD is also further advancing its existing PV technology toward the goal of 14% stable solar cells by performing the following four tasks: (1) improving the stability of the intrinsic a-Si alloy materials; (2) improving the quality of low-band-gap a-SiGe alloy; (3) improving p{sup +} window layers, and (4) developing high stable-efficiency triple-junction a-Si alloy solar cells.

Deng, X. [Energy Conversion Devices, Inc., Troy, MI (United States)

1996-02-01T23:59:59.000Z

184

Amorphous thin films for solar-cell applications. Final report, September 11, 1978-September 10, 1979  

Science Conference Proceedings (OSTI)

In Section II, Theoretical Modeling, theories for the capture of electrons by deep centers in hydrogenated amorphous silicon (a-Si:H) and for field-dependent quantum efficiency in a-Si:H are presented. In Section III, Deposition and Doping Studies, the optimization of phosphorus-doped a-Si:H carried out in four different discharge systems is described. Some details of the dc proximity and rf magnetron discharge systems are also provided. Preliminary mass spectroscopy studies of the rf magnetron discharge in both SiH/sub 4/ and SiF/sub 4/ are presented. In Section IV, Experimental Methods for Characterizing a-Si:H, recent work involving photoluminescence of fluorine-doped a-Si:H, photoconductivity spectra, the photoelectromagnetic effect, the photo-Hall effect and tunneling into a-Si:H is presented. Also, studies of the growth mechanism of Pt adsorbed on both crystalline Si and a-Si:H are described. Measurements of the surface photovoltage have been used to estimate the distribution of surface states of phosphorus-doped and undoped a-Si:H. Section V, Formation of Solar-Cell Structures, contains information on stacked or multiple-junction a-Si:H solar cells. In Section VI, Theoretical and Experimental Evaluation of Solar-Cell Parameters, an upper limit of approx. = 400 A is established for the hole diffusion length in undoped a-Si:H. A detailed description of carrier generation, recombination and transport in a-Si:H solar cells is given. Finally, some characteristics of Pd-Schottky-barrier cells are described for different processing histories.

Carlson, D E; Balberg, I; Crandall, R S; Goldstein, B C; Hanak, J J; Pankove, J I; Staebler, D L; Weakliem, H A; Williams, R

1980-02-01T23:59:59.000Z

185

Deposition of a-SiC:H, a-SiO{sub 2} and tetrahedral-C with programmable in-situ etching. Final performance report, March 1, 1988--November 30, 1991  

DOE Green Energy (OSTI)

This research program was originally defined to investigate the deposition of semiconductor and dielectric thin films using a low pressure remote plasma chemical vapor deposition system incorporating a process for etching the films. This etching was to be performed in a periodic fashion during the deposition process to remove defect regions in the film being deposited. The goal was to remove voids and other defects which are characteristic of low temperature deposition processes. While the original research proposal suggested that the studies include the amorphous alloys (Si/C):H and (Si/Ge):H, subsequent funding reductions limited the work to the deposition of an amorphous silicon alloy material (a-Si:H). Intrinsic and doped forms of these materials have applications in the fabrication of single and multi-junction thin film solar cells.

Collis, W.J.

1995-06-01T23:59:59.000Z

186

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

DOE Patents (OSTI)

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.

Findikoglu, Alp T. (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM); Arendt, Paul N. (Los Alamos, NM); Matias, Vladimir (Santa Fe, NM); Choi, Woong (Los Alamos, NM)

2009-10-27T23:59:59.000Z

187

Amorphous semiconductor solar cell  

SciTech Connect

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.

Dalal, Vikram L. (Newark, DE)

1981-01-01T23:59:59.000Z

188

Research on stable, high-efficiency amorphous silicon multijunction modules. Annual subcontract report, 1 January 1992--28 February 1993  

DOE Green Energy (OSTI)

This report describes the progress made during Phase 2 of the R&D program to obtain high-efficiency amorphous alloy multijunction PV (photovoltaic) modules. The highlight of the work includes: (1) demonstration of world-record small-area efficiency of 11.2% after one-sun light-soaking at 50{degrees}C for 600 h using a dual band gap, double-junction structure; and (2) demonstration of initial module efficiency of 10.6% over 0.09-m{sup 2} (1-ft{sup 2}) area using the same double-junction approach. In addition, fundamental studies on material properties and cell performance have shown an interesting correlation between microstructure in the material and cell efficiency both in the initial and light-degraded conditions.

Guha, S. [United Solar Systems Corp., Troy, MI (US)

1993-07-01T23:59:59.000Z

189

Research on the structural and electronic properties of defects in amorphous silicon. Final subcontract report, September 1989--December 1990  

DOE Green Energy (OSTI)

The work performed for this contract focused on the saturation of light-induced effects, hydrogen-mediated metastability and growth, defects and electronic properties, and remote hydrogen plasma growth. This work included research on hydrogen chemical reactions, hydrogen density-of-states model and metastability, hydrogen bonding configurations, a model for the role of hydrogen complexes in the metastability, and hydrogen chemical potential and growth structure. This document also covers research on thermal generation currents in p-i-n diodes, field dependence of the generation current, metastability effects at contacts, and potential fluctuations in compensated a-Si:H. Information is included on plasma diagnostics using electron spin resonance and nuclear magnetic resonance measurements of remote hydrogen plasma films.

Street, R.A. [Xerox Palo Alto Research Center, CA (United States)

1991-12-01T23:59:59.000Z

190

Studies on relative effects of charged and neutral defects in hydrogenated amorphous silicon. Final report, 1 October 1989--31 December 1990  

DOE Green Energy (OSTI)

This report covers the third year of a continuing research study to understand the relative importance of charged and neutral defects in amorphous silicon. The objective of the study is to explore the electronic structure, including neutral and charged defects, an optoelectronic effects including the formation of Staebler-Wronski defects. The study concentrated on exploring electroluminescence experimentally and interpreting the results employing a simple guiding model. The simple guiding model assumes an exponential density of states and recombination rate constants (radiative and non-radiative) which are governed by hopping transitions. Measurements were also made as a function of photodegradation of the material. The results implicate that the radiative recombination processes are not distant pair tunneling but rather results from electrons hopping down due to the coulomb interactions. Preliminary experiments have been made on the effect of photodegradation on transient space charge limited currents in n/i/n structures. These experiments can directly yield information on the occupied defects centers induced by the photodegradation and are not a result of recombination processes. To date the results seems to be consistent with a picture which places the doubly occupied defects at quite a high energy ({approx_equal} 0.4 e.v. below the conduction band).

Silver, M. [North Carolina Univ., Chapel Hill, NC (United States)

1992-02-01T23:59:59.000Z

191

Recombination and metastability in amorphous silicon and silicon-germanium alloys. Final subcontract report, 1 February 1991--31 January 1994  

DOE Green Energy (OSTI)

Electroluminescence-spectra- and transient-current measurements were taken before and after light-soaking a-Si:H p-i-n structures. For the first time, we were able to distinguish between bulk- and junction-controlled recombination. We found that in buffered p-b-i-n structures, the main-band luminescence was more pronounced than that in simple p-i-n structures. The enhancement of the main-band luminescence relates with an increase of the open-circuit voltage. This is evidence that the recombination takes place near the p-i interface, and the quality of the p-i interface is very important in solar cell performance. We also found that for thick p-i-n cells ({ge}2 {mu}m), the luminescence contains more high-energy photons (1.1--1.2 eV) than does that for thin cells. Furthermore, the high-energy recombination is more efficient in creating metastable defects than is the low-energy recombination. Consequently, the thinner the i-layer, the less the light-induced effects. The results of repetition rate and reverse bias effects on forward-bias current imply that the junctions recover faster than the bulk when subjected to excess carriers caused by the bias. By including the coulomb interaction, we made progress on a microscopic model for radiative recombination.

Silver, M.; Han, D.X.; Wang, K.D.; Kemp, M. [North Carolina Univ., Chapel Hill, NC (United States)

1994-07-01T23:59:59.000Z

192

Search for the Factors Determining the Photodegradation in High Efficiency a-Si:H Solar Cells: Final Subcontract Report, 28 January 1998 - 15 August 2001  

DOE Green Energy (OSTI)

This report describes continuing studies on photoluminescence (PL), electroluminescence (EL), Raman, and nuclear magnetic resonance (NMR) by the University of North Carolina-Chapel Hill during the three years and the extension period. Systematic studies on the transition materials and their solar cells and a review of the photo-induced structural changes in correlation to the electronic degradation have led to better understanding of the factors determining the photodegradation in a-Si:H solar cells. NHR established significant differences, as in the bonding of hydrogen in the hot-wire- and plasma-deposited amorphous silicon.

Han, D.

2002-03-01T23:59:59.000Z

193

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

SciTech Connect

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.

Deng, X.

2006-01-01T23:59:59.000Z

194

Novel silane and disilane precursors to amorphous semiconductors. Annual report, 1 April 1985-31 March 1986  

SciTech Connect

This report describes the preparation and characterization of amorphous fluorohydrogenated silicon thin films. The novel approach lies in the use of fluorinated silanes as film precursors. This method has the advantages of well-defined initial ratios of hydrogen and fluorine and a greatly reduced hazards in the handling of the gas. Fluorine derivatives of both silane and disilane were synthesized. A conventional method, glow discharge (or plasma-enhanced chemical vapor deposition), was employed to prepare amorphous silicon on glass and Si wafers. The electrical characterization of the material prepared from difluorosilane (the main precursor during the contract period covered in this report) showed that the a-Si:H:F films obtained are of solar-grade semiconductor quality and can be doped to p- and n-type material with diborane and phosphine.

Pernisz, U.; Sharp, K.

1986-08-01T23:59:59.000Z

195

Diagnostics of a glow discharge used to produce hydrogenated amorphous silicon films. Final report, April 15, 1982-April 14, 1983  

DOE Green Energy (OSTI)

The amount of silane reacted in a discharge is studied. The dependence of the fraction of reacted silane and the product forms on discharge conditions is studied. Results indicate the criteria for rapid, efficient film deposition, and the discharge and flow conditions that induce major modifications of the gas and probably of the depositing species. The discharge energy efficiency is also obtained as well as silane-use efficiency in pure silane and silane-noble gas mixtures. In-situ film-deposition rate monitors have been developed and used to study deposition as a function of discharge conditions. Further study has concentrated on the discharge ion species and the collisional processes which control the mixture of ion species. It is confirmed that the ion deposition is a relatively small fraction of all silicon deposition in dc discharges. Total electron collisional ionization of silane and disilane were measured, as well as the partial cross sections for producing various product ions. Ion-molecule reactions are also measured. (LEW)

Gallagher, A.; Scott, J.

1982-01-01T23:59:59.000Z

196

Amorphous-diamond electron emitter  

DOE Patents (OSTI)

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.

Falabella, Steven (Livermore, CA)

2001-01-01T23:59:59.000Z

197

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

DOE Green Energy (OSTI)

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.

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

1995-03-01T23:59:59.000Z

198

Fundamental studies of defect generation in amorphous silicon alloys grown by remote plasma-enhanced chemical-vapor deposition (Remote PECVD)  

DOE Green Energy (OSTI)

We demonstrated that the remote PECVD process can be used to deposit heavily doped n-type and p-type a-Si:H thin films. We optimized conditions for depositing undoped, near-intrinsic and heavily doped thin films of [mu]c(microcrystalline)-Si by remote PECVD. We extended the remote PECVD process to the deposition of undoped and doped a-Si,C:H and [mu]c-Si,C alloy films. We analyzed transport data for the dark conductivity in undoped and doped a-Si:H, a-Si,C:H, [mu]c-Si and [mu]c-Si,C films. We studied the properties of doped a-Si:H and [mu]c-Si in MOS capacitors using [approximately]10 [Omega]-cm p-type crystalline substrates and thermally grown Si0[sub 2] dielectric layers. We collaborated with a group at RWTH in Aachen, Germany, and studied the contributions of process induced defect states to the recombination of photogenerated electron pairs. We applied a tight-binding model to Si-Bethe lattice structures to investigate the effects of bond angle, and dihedral angle disorder. We used ab initio and empirical calculations to study non-random bonding arrangements in a-Si,O:H and doped a-Si:H films.

Lucovsky, G.; Nemanich, R.J.; Bernholc, J.; Whitten, J.; Wang, C.; Davidson, B.; Williams, M.; Lee, D.; Bjorkman, C.; Jing, Z. (North Carolina State Univ., Raleigh, NC (United States))

1993-01-01T23:59:59.000Z

199

Silicon MOS inductor  

DOE Patents (OSTI)

A device made of amorphous silicon which exhibits inductive properties at certain voltage biases and in certain frequency ranges in described. Devices of the type described can be made in integrated circuit form.

Balberg, Isaac (Princeton, NJ)

1981-01-01T23:59:59.000Z

200

Defect states in plasma-deposited a-Si:H. Technical progress report, May-July 1979  

DOE Green Energy (OSTI)

Three preprints are presented. The first, entitled ''Glow Discharge Optical Spectroscopy Measurement of Dopant Concentrations in a-Si:H,'' reports significant differences between the ratio of boron to silicon of the films and that of their deposition plasmas. The second, entitled ''Growth Morphology and Defects in Plasma-Deposited a-Si:H Films,'' presents structural studies that show that a major class of defect is an anisotropic density fluctuation. Studies of the hydrogen environment suggest that an inhomogeneous hydrogen distribution is associated with these fluctuations. From considerations of the deposition chemistry and nucleation theory, a model is proposed to describe the film growth process and its relationship to defects. The third, entitled ''Luminescence and ESR Studies of Defects in Hydrogenated Amorphous Silicon,'' demonstrates that the two experiments involve identical recombination transitions, and identify two separate processes. One process involves defect states, and from the doping dependence of light induced ESR, it is deduced that the electronically active defects are dangling bonds with positive electronic correlation energy. (LEW)

Knights, J C

1979-09-21T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Investigations of the origins of metastable light-induced changes in hydrogenated amorphous silicon. Final subcontract report, April 1, 1988--March 31, 1991  

DOE Green Energy (OSTI)

The work performed for this contract continued investigations of the origins of metastable effectS in a-Si:H through three kinds of studies: (1) the effect of carbon impurities in a-Si:H samples at low concentrations using drive-level capacitance profiling measurements on samples whose carbon content was intentionally modulated spatially during growth, (2) the characterization of metastable states in n-type doped a Si:H samples caused by quench cooling and by light-soaking with partial annealing, and (3) the use of depletion-width-modulated ESR spectroscopy together with junction capacitance spectroscopy to investigate deep defect states for various metastable states of a 10- and an 80-Vppm PH{sub 3}-doped a-Si:H sample.

Cohen, J.D. [Oregon Univ., Eugene, OR (United States)

1991-12-01T23:59:59.000Z

202

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

DOE Green Energy (OSTI)

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.

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

1999-12-17T23:59:59.000Z

203

Thermal decomposition of silane to form hydrogenated amorphous Si film  

DOE Patents (OSTI)

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.

Strongin, Myron (Center Moriches, NY); Ghosh, Arup K. (Rocky Point, NY); Wiesmann, Harold J. (Wantagh, NY); Rock, Edward B. (Oxford, GB); Lutz, III, Harry A. (Midlothian, VA)

1980-01-01T23:59:59.000Z

204

Research on silicon-carbon alloys and interfaces. Final subcontract report, 15 February 1991--31 July 1994  

DOE Green Energy (OSTI)

This report describes work performed to develop improved p-type wide-band-gap hydrogenated amorphous silicon-carbon alloy (a-Si{sub 1-x}C{sub x:}H) thin films and interfaces for the ``top junction`` in hydrogenated amorphous silicon (a-Si:H)-based p-i-n solar cells. We used direct current reactive magnetron sputtering to deposit undoped a-Si{sub 1-x}C{sub x}H films with a Tauc band gap E{sub g} of 1.90 eV, a sub-band-gap absorption of 0.4 (at 1.2 eV), an Urbach energy of 55 MeV, an ambipolar diffusion length of 100 nm, an air-mass-one photoconductivity of 10{sup {minus}6}/{Omega}-cm, and a dark conductivity of 8{times} 1O{sup {minus}11}/{Omega}-cm. p{sup +}a-Si{sub 1-x}C{sub x}:H films with a Tauc band gap of 1.85 eV have a dark conductivity of 8 {times} 10{sup {minus}6}/{Omega}-cm and thermal activation energy of 0.28 eV. We used in-situ spectroscopic ellipsometry and post-growth X-ray photoelectron spectroscopy to determine the relative roles of H and Si in the chemical reduction of SnO{sub 2} in the early stages of film growth. We used in-situ spectroscopic ellipsometry to show that a-Si:H can be transformed into {mu}c-Si:H in a subsurface region under appropriate growth conditions. We also determined substrate cleaning and ion bombardment conditions which improve the adhesion of a-Si{sub 1-x}C{sub x}:H films.

Abelson, J.R. [Illinois Univ., Urbana, IL (United States)

1995-07-01T23:59:59.000Z

205

Small-angle x-ray scattering studies of microvoids in amorphous silicon-based semiconductors. Annual subcontract report, 1 February 1992--31 January 1993  

DOE Green Energy (OSTI)

This report describes work to provide now details of the microstructure for the size scale from about 1 nm to 30 nm in high-quality a-Si:H and related alloys prepared by current state-of-the-art deposition methods as well as by now and emerging deposition technologies to help determine the role of microvoids and other density fluctuations in controlling the opto-electronic properties. The objectives are to determine whether the presence of microstructure as detected by small-angle X-ray scattering (SAXS) (1) limits the photovoltaic (PV) properties of device-quality a-Si:H; (2) plays a role in determine the photostability of a-Si:H; and (3) is responsible for degradation of the PV properties due to alloying with Ge, C, and other constituents. We collaborated with several groups that can supply relevant systematic sets of samples and the associated opto-electronic data to help address these issues. The project also included developing a method to standardize the procedures, minimize substrate influences, and implement improved data reduction and modeling methodology.

Williamson, D.L.; Jones, S.J.; Chen, Y. [Colorado School of Mines, Golden, CO (United States)

1994-06-01T23:59:59.000Z

206

Research on high-efficiency, single-junction, monolithic, thin-film amorphous silicon solar cells: Phase II annual subcontract report, 1 January 1985--31 January 1986  

DOE Green Energy (OSTI)

This report presents results of the second phase of research on high-efficiency, single-junction, monolithic, thin-film a-Si solar cells. Five glow-discharge deposition systems, including a new in-line, multichamber system, were used to grow both doped and undoped a-Si:H. A large number of silane and disilane gas cylinders were analyzed with a gas chromatography/mass spectroscopy system. Strong correlations were found between the breakdown voltage, the deposition rate, the diffusion length, and the conversion efficiency for varying cathode-anode separations in a DC glow-discharge deposition mode. Tin oxide films were grown by chemical vapor deposition with either tetramethyl tin (TMT) or tin tetrachloride (TTC). The best were grown with TMT, but TTC films had a more controlled texture for light trapping and provided a better contact to the p-layer. The best results were obtained with 7059 glass substrates. Efficiencies as high as 10.86% were obtained in p-i-n cells with superlattice p-layers and as high as 10.74% in cells with both superlattice p- and n-layers. Measurements showed that the boron-doping level in the p-layer can strongly affect transport in the i-layer, which can be minimized by reactive flushing before i-layer deposition. Stability of a-Si:H cells is improved by light doping. 51 refs., 64 figs., 21 tabs.

Carlson, D.E.; Ayra, R.R.; Bennett, M.S.; Catalano, A.; D'Aiello, R.V.; Dickson, C.R.; McVeigh, J.; Newton, J.; O'Dowd, J.; Oswald, R.S.; Rajan, K.

1988-09-01T23:59:59.000Z

207

Efficiency and Throughput Advances in Continuous Roll-to-Roll a-Si Alloy PV Manufacturing Technology: Final Subcontract Report, 22 June 1998 -- 5 October 2001  

DOE Green Energy (OSTI)

This report describes a roll-to-roll triple-junction amorphous silicon alloy PV manufacturing technology developed and commercialized by Energy Conversion Devices (ECD) and United Solar Systems. This low material cost, roll-to-roll production technology has the economies of scale needed to meet the cost goals necessary for widespread use of PV. ECD has developed and built six generations of a-Si production equipment, including the present 5 MW United Solar manufacturing plant in Troy, Michigan. ECD is now designing and building a new 25-MW facility, also in Michigan. United Solar holds the world's record for amorphous silicon PV conversion efficiency, and manufactures and markets a wide range of PV products, including flexible portable modules, power modules, and innovative building-integrated PV (BIPV) shingle and metal-roofing modules that take advantage of this lightweight, rugged, and flexible PV technology. All of United Solar's power and BIPV products are approved by Underwriters Laboratories and carry a 10-year warranty. In this PVMaT 5A subcontract, ECD and United Solar are addressing issues to reduce the cost and improve the manufacturing technology for the ECD/United Solar PV module manufacturing process. ECD and United Solar identified five technology development areas that would reduce the module manufacturing cost in the present 5-MW production facility, and also be applicable to future larger-scale manufacturing facilities.

Ellison, T.

2002-04-01T23:59:59.000Z

208

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  

Science Conference Proceedings (OSTI)

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.

Sopori, B.

2012-04-01T23:59:59.000Z

209

Experimental study of the factors governing the Staebler-Wronski photodegradation effect in a-Si:H solar cells. Final technical report, July 7, 1994--January 15, 1998  

DOE Green Energy (OSTI)

This report describes continuing studies on electroluminescence (EL), field profile, and hydrogen microstructure by the University of North Carolina, Chapel Hill, during the third year and the extension period. Based on systematic studies of the EL, the authors developed a complete model to explain the unique features of the EL as dispersive-transport-controlled, non-geminate recombinant processes. This model can explain the main features of the EL, not only in hydrogenated amorphous silicon (a-Si:H), but also in other types of trap-rich materials. By employing the forward current and EL temperature-dependence studies, information of both the localized tail states and the deep defect states in real solar-cell structures were obtained concomitantly, which is crucial for the device performance. The authors measured the internal electric field profile in p-i-n and n-i-p cells by a null-current method; they studied the structure of the hydrogen clusters in hot-wire a-Si:H films, both theoretically and experimentally, and show a clear evidence of improved structural order in hot-wire a-Si:H, which is an important factor leading to more stable materials. To link the film microstructure to the metastability, the authors also started the film stress measurements.

Han, D. [Univ. of North Carolina, Chapel Hill, NC (United States)

1998-05-01T23:59:59.000Z

210

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

DOE Green Energy (OSTI)

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.

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

1994-11-01T23:59:59.000Z

211

Deposition of amorphous silicon solar cells at high rates by glow discharge of disilane. Final subcontract report, January 1985-July 1986  

DOE Green Energy (OSTI)

This report summarizes the results of recent a-Si:H thin-film photovoltaic (PV) materials research. The work reported here concerned the fabrication of a-Si:H solar cells at high deposition rates using disilane. This task required the construction of a new, dual-chamber deposition system to control the dopant profile between the heavily doped p-type layer and the undoped (intrinsic) layer in the solar cell structure. Conditions were sought that would produce high-quality films at a high deposition rate. Complete photovoltaic devices were fabricated. In disilane-deposited material, the optimum substrate temperature is much higher than in silane material, presumably because it is harder to eliminate the excess hydrogen in the former. The efficiency of the best disilane cell was about 7%, with an open-circuit voltage of 0.80 V, a short-circuit current density of 14.7 mA cm/sup -2/ and a fill factor of 0.59. The most likely area for improvement is in the voltage, where values as high as 0.9 V should be possible with careful adjustment of the cell structure.

Vanier, P.E.

1986-08-01T23:59:59.000Z

212

Optimization of interdigitated back contact silicon heterojunction solar cells by two-dimensional numerical simulation  

DOE Green Energy (OSTI)

In this paper, two-dimensional (2D) simulation of interdigitated back contact silicon heterojunction (IBC-SHJ) solar cells is presented using Sentaurus Device, a software package of Synopsys TCAD. A model is established incorporating a distribution of trap states of amorphous-silicon material and thermionic emission across the amorphous-silicon / crystalline-silicon heterointerface. The 2D nature of IBC-SHJ device is evaluated and current density-voltage (J-V) curves are generated. Optimization of IBC-SHJ solar cells is then discussed through simulation. It is shown that the open circuit voltage (VOC) and short circuit current density (JSC) of IBC-SHJ solar cells increase with decreasing front surface recombination velocity. The JSC improves further with the increase of relative coverage of p-type emitter contacts, which is explained by the simulated and measured position dependent laser beam induced current (LBIC) line scan. The S-shaped J-V curves with low fill factor (FF) observed in experiments are also simulated, and three methods to improve FF by modifying the intrinsic a-Si buffer layer are suggested: (i) decreased thickness, (ii) increased conductivity, and (iii) reduced band gap. With all these optimizations, an efficiency of 26% for IBC-SHJ solar cells is potentially achievable.

Lu, Meijun; Das, Ujjwal; Bowden, Stuart; Hegedus, Steven; Birmire, Robert

2009-06-09T23:59:59.000Z

213

Low-pressure chemical vapor deposition of amorphous silicon photovoltaic devices. Annual technical progress report, 1 May 1984-30 April 1985  

DOE Green Energy (OSTI)

Intrinsic and doped a-Si:H films were deposited by low pressure chemical vapor deposition (CVD) for disilane. Intrinsic layers were deposited at growth rates as high as 50 A/s. A chemical reaction engineering model that quantitatively describes the CVD reactor behavior has been developed. CVD intrinsic material was characterized by measurements of impurities, optical band gap, photoconductivity, activation energy, diffusion length, and density of states. Photovoltaic cells of the p-i-n type with efficiencies of 4% and 3.6% were fabricated using CVD intrinsic layers deposited at 1 A/s and 9 A/s, respectively. A maximum short-circuit current of 11 mA/cm/sup 2/ under 87.5 MW/cm/sup 2/ ELH illumination was obtained with boron-compensated CVD intrinsic material. Efficiency-limiting mechanisms in CVD cells were quantitatively analyzed and related to fundamental properties.

Baron, B.N.; Rocheleau, R.E.; Hegedus, S.S.

1986-02-01T23:59:59.000Z

214

Large-area, triple-junction a-Si alloy production scale-up. Semiannual subcontract report, 17 March 1993--18 September 1993  

DOE Green Energy (OSTI)

This report describes work to improve the efficiency of large-area, multi-junction amorphous silicon (a-Si) alloy modules. Equipment capable of producing modules up to 0.74 m{sup 2} in area is on line and process development has begun. Preliminary cost analysis/reduction has begun to ensure that these development efforts will result in a commercialization of the large-area technology. The approach was to transfer the high-efficiency multi-junction technology from R&D into the manufacturing environment by using three different substrate sizes. Initial attempts to transfer the multijunction silicon process were made using a 0.1-m{sup 2} substrate (approximately 1 ft{sup 2}). These efforts resulted in a module with a measured aperture area efficiency of 10.32%. Simultaneous with the transfer of the silicon technology, the most complicated aspect of the technology transfer, Solarex began process development techniques on large-area modules by using the 0.37-m{sup 2} substrates. These efforts resulted in modules with a total area efficiency of 7%. Finally, initial runs on substrates 0.74 m{sup 2} were made to debug the large-area equipment in preparation of transferring the knowledge gained in the processing of the smaller substrates.

Oswald, R.; O`Dowd, J.; Ashenfelter, W. [Solarex Corp., Newtown, PA (United States). Thin Film Div.] [and others

1994-03-01T23:59:59.000Z

215

Thin-film amorphous silicon alloy research partnership. Phase 2, Annual technical progress report, 2 February 1996--1 February 1997  

DOE Green Energy (OSTI)

This is Phase II of a 3-phase, 3-year program. It is intended to expand, enhance, and accelerate knowledge and capabilities for developing high-performance, two-terminal multijunction amorphous Si alloy modules. We discuss investigations on back reflectors to improve cell performance and investigate uniformity in performance over a 1-sq.-ft. area. We present results on component cell performance, both in the initial and in the light-degraded states, deposited over a 1-sq.-ft. area. The uniformity in deposited is investigated by studying the performance of subcells deposited over the entire area. We also present results on the performance of triple- junction cells and modules. The modules use grid-lines and encapsulants compatible with our production technology. We discuss the novel laser-processing technique that has bee developed at United Solar to improve energy-conversion efficiency and reduce manufacturing costs. We discuss in detail the optimization of the processing steps, and the performance of a laser-processed, triple- junction device of 12.6 cm{sup 2} area is presented. We also present experimental results on investigations of module reliability.

Guha, S. [United Solar Systems Corp., Troy, MI (United States)

1997-06-01T23:59:59.000Z

216

Diagnostics of glow discharges used to produce hydrogenated amorphous silicon films: Annual subcontract report, 15 April 1986-14 June 1987  

DOE Green Energy (OSTI)

This report presents results of research done to measure the neutral species produced in silane, silane-hydrogen, disilane, disilane-hydrogen, germane, germane-hydrogen, and silane-germane discharges. Interpretation and modeling of the data in terms of discharge chemistry are also desirable. Mass-spectrometric measurements were made of the stable gases flow through and produced in silane, disilane, and silane-germane discharges. From these observations, the discharge stoichiometry was determined and the reaction pathways that lead to film deposition clarified. The importance of one processing parameter (powerflow) is explained, and a high ratio of germanesilane depletion in mixed-gas discharges is identified. A calculation of radical deposition in pure silane discharges shows the dominance of SiH/sub 3/ deposition at low powers and suggests the reason (surface mobility) why this produced good-quality films. Measurements of postdeposition sputtering of a-Si:H films were important in understanding and modeling the deposition reactions as well as the high-rate deposition method was also developed and studied.

Gallagher, A.; Doyle, J.; He, M.; Lin, G.H.; Scott, J.

1988-01-01T23:59:59.000Z

217

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

SciTech Connect

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.

Carey, Paul G. (Mountain View, CA); Thompson, Jesse B. (Brentwood, CA)

1994-01-01T23:59:59.000Z

218

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

DOE Patents (OSTI)

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.

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

1994-11-01T23:59:59.000Z

219

Research on amorphous-silicon-based thin-film photovoltaic devices: Semiannual subcontract report, 1 July 1987--31 December 1987  

DOE Green Energy (OSTI)

The objective of this work is to develop 13% (aperture area) efficient, 850-cm/sup 2/ four-terminal hybrid tandem submodules. The module design consists of a copper-indium-diselenide (CIS)-based bottom circuit and a semitransparent, thin-film silicon-hydrogen (TFS)-based top circuit. High-performance, semitransparent TFS devices and submodules were fabricated in which ZnO was used in the front and rear transparent conductors. High-performance CIS devices and submodules were also fabricated; however, the location and nature of the junction are not yet understood. Representative four-terminal hybrid tandem devices and submodules were fabricated from TFS and CIS component circuits. Optical coupling between the circuits was lower than expected, because of reflection losses at key interfaces. Efficiencies obtained for these devices and modules include 14.17% for a four-terminal, 4-cm/sup 2/ tandem cell and 12.3% for a four-terminal, tandem module. 7 refs., 90 figs.

Bottenberg, W.; Mitchell, K.; Wieting, R.

1988-05-01T23:59:59.000Z

220

Influence of thin metal as a top electrode on the characteristics of P-I-N a- Si:H solar cells  

Science Conference Proceedings (OSTI)

Hydrogenated amorphous silicon (a-Si:H) p-n junction solar cells have been fabricated which utilize various metals (Cr, Cu, Al, Pd, Ag) as a top electrode. Experimental and theoretical analysis of photovolatic performance in a-Si:H solar cells as a function of resistivity, optical transmittance, and work function of thin metal films are presented. Metal work function changes the effective built-in potential of p-n junction diodes. Furthermore, a lower work function metal forms a good Ohmic contact for substrate --P/sup +/-I-N/sup +/-- electrode cells, and high work function metals improve V/sub oc/ of substrate -N-I-P cells. Typical V/sub o/c values are 760 mV with Cr--, Cu--, and Al--N-I-P--stainless steel (SS), 700 mV with Pd--N-I-P-SS, 600 mV with Pd--P-I-N-SS, and 540 mV with Cr--P-I-N-SS. J/sub sc/ is strongly dependent on transmittance and resistivity of the metal films. Fill factor is independent of the choice of a top electrode. An efficient of 2% has been obtained on a 2 cm/sup 2/ solar cell.

Han, M.; Anderson, W.A.; Lahri, R.; Coleman, J.

1981-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Fundamental studies of defect generation in amorphous silicon alloys grown by remote plasma-enhanced chemical-vapor deposition (Remote PECVD). Annual subcontract report, 1 September 1990--31 August 1991  

DOE Green Energy (OSTI)

We demonstrated that the remote PECVD process can be used to deposit heavily doped n-type and p-type a-Si:H thin films. We optimized conditions for depositing undoped, near-intrinsic and heavily doped thin films of {mu}c(microcrystalline)-Si by remote PECVD. We extended the remote PECVD process to the deposition of undoped and doped a-Si,C:H and {mu}c-Si,C alloy films. We analyzed transport data for the dark conductivity in undoped and doped a-Si:H, a-Si,C:H, {mu}c-Si and {mu}c-Si,C films. We studied the properties of doped a-Si:H and {mu}c-Si in MOS capacitors using {approximately}10 {Omega}-cm p-type crystalline substrates and thermally grown Si0{sub 2} dielectric layers. We collaborated with a group at RWTH in Aachen, Germany, and studied the contributions of process induced defect states to the recombination of photogenerated electron pairs. We applied a tight-binding model to Si-Bethe lattice structures to investigate the effects of bond angle, and dihedral angle disorder. We used ab initio and empirical calculations to study non-random bonding arrangements in a-Si,O:H and doped a-Si:H films.

Lucovsky, G.; Nemanich, R.J.; Bernholc, J.; Whitten, J.; Wang, C.; Davidson, B.; Williams, M.; Lee, D.; Bjorkman, C.; Jing, Z. [North Carolina State Univ., Raleigh, NC (United States)

1993-01-01T23:59:59.000Z

222

Amorphous Silicon Array for Medical Imaging  

Victor Perez-Mendez and Selig Kaplan at Berkeley National Laboratory are developing a new technology for charged particle and x-ray detection using ...

223

Amorphous Silicon-Carbon Nanostructure Photovoltaic Devices  

E-Print Network (OSTI)

way to do better. A photovoltaic cell, or solar cell, is aFor this thesis, I made photovoltaic cells using a Schottkyphotovoltaic processes oc- cur in a Schottky barrier solar cell. . . . . . . . . . . . . . . . . .

Schriver, Maria Christine

2012-01-01T23:59:59.000Z

224

Amorphous Silicon-Carbon Nanostructure Photovoltaic Devices  

E-Print Network (OSTI)

relatively expensive indium tin oxide layers, in addition toH on patterned indium tin oxide (ITO) on glass substrates

Schriver, Maria Christine

2012-01-01T23:59:59.000Z

225

Photovoltaics Using Doped and Undoped Amorphous Silicon ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Polymer based photovoltaic (PV) technology is an exciting ... this area are few and there is a need for in-depth analysis of Si-organic interfaces.

226

In Situ TEM Investigation of Congruent Phase Transition and Structural Evolution of Nanostructured Silicon/Carbon Anode for Lithium Ion Batteries  

Science Conference Proceedings (OSTI)

It is well known that upon lithiation both crystalline and amorphous Si transform to a armorphous LixSi phase, which subsequently crystallizes to a (Li, Si) crystalline compound, either Li15Si or Li22Si5. Up to date, the detailed atomistic mechanism of this phase transformation, and degradation process in nanostructured Si, are not fully understood. Here, we report the microstructural evolution and phase transformation characteristic of a specially designed amorphous silicon (a-Si) coated carbon nanofiber (CNF) composite during charge/discharge process using in-situ TEM and density function theory molecular dynamic (DFT-MD) calculation. We found that the crystallization of Li15Si4 from amorphous LixSi is a spontaneous, congruent phase transition process without phase separation or large scale atomic motion, which is drastically different from what is expected from a classic nucleation and growth process. The a-Si layer is strongly bonded to the CNF and no spallation or cracking is observed during the early stages of cyclic charge/discharge. Reversible volume expansion/contraction upon charge/discharge is fully accommodated along the radial direction. However, with progressive cycling, damage in the form of surface roughness was gradually accumulated on the coating layer, which is believed to be the mechanism for the eventual capacity fade of the composite anode during long term charge/discharge cycling.

Wang, Chong M.; Li, Xiaolin; Wang, Zhiguo; Xu, Wu; Liu, Jun; Gao, Fei; Kovarik, Libor; Zhang, Jiguang; Howe, Jane; Burton, David J.; Liu, Zhongyi; Xiao, Xingcheng; Thevuthasan, Suntharampillai; Baer, Donald R.

2012-03-02T23:59:59.000Z

227

Theory of amorphous ices  

E-Print Network (OSTI)

We use large-deviation theory to study nonequilibrium transitions between amorphous solids and liquid in an atomistic model of supercooled water. Along with nonequilibrium transitions between the ergodic liquid and two distinct amorphous solids, we establish coexistence between the two amorphous solids, a finding that is consistent with experiment. The phase diagram we predict includes a nonequilibrium triple point where the two amorphous phases and the liquid coexist. While the amorphous solids are long-lived and slowly-aging glasses, their melting leads quickly to the formation of ice. This irreversible behavior is demonstrated in our theoretical treatment and compared with experiment.

David T Limmer; David Chandler

2013-06-20T23:59:59.000Z

228

Effect of a surface pre-treatment on graphene growth using a SiC substrate  

Science Conference Proceedings (OSTI)

This study reports surface pre-treatment techniques for the formation of a high-quality graphene layer on a SiC surface. It is demonstrated that silicon passivation of SiC surface using a silane flow and subsequent sacrificial oxidation can significantly ... Keywords: Graphene, Sacrificial oxidation, Silane treatment, Sulfur hexafluoride (SF6), Surface passivation

Jun-Ho Seo; Byung-Jin Kang; Jeong Hun Mun; Sung-Kyu Lim; Byung Jin Cho

2010-10-01T23:59:59.000Z

229

Method for processing silicon solar cells  

DOE Patents (OSTI)

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.

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

1997-05-06T23:59:59.000Z

230

Method for processing silicon solar cells  

DOE Patents (OSTI)

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.

Tsuo, Y. Simon (Golden, CO); Landry, Marc D. (Lafayette, CO); Pitts, John R. (Lakewood, CO)

1997-01-01T23:59:59.000Z

231

Diamond-silicon carbide composite and method  

DOE Patents (OSTI)

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.

Zhao, Yusheng (Los Alamos, NM)

2011-06-14T23:59:59.000Z

232

Scanning tunneling microscopy studies of the surfaces of a-Si:H and a-SiGe:H films  

SciTech Connect

The report contains a detailed description of the experimental complexities encountered in developing scanning tunneling microscope (STM) probing of atomic structure on the surface of freshly-grown hydrogenated-amorphous semiconductors. It also contains a speculative microscopic film-growth model that explains differences between the disorder in CVD grown a-Ge:H versus a-Si:H films. This model is derived from prior results obtained in the chemical analysis of GeH{sub 4} plasmas, combined with surface reaction and thermodynamic considerations. The neutral radical fragments of silane, disilane and germane dissociation in discharges, which dominate the vapor and film-growth reactions, have been deduced from detailed analysis of prior data and are reported. 4 refs., 7 figs.

Gallagher, A.; Ostrom, R.; Tannenbaum, D. (National Inst. of Standards and Technology, Boulder, CO (USA))

1991-06-01T23:59:59.000Z

233

Silicon Oxynitride Thin Film Barriers for PV Packaging (Poster)  

DOE Green Energy (OSTI)

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.

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.

2006-10-03T23:59:59.000Z

234

Identifying Electronic Properties Relevant to Improving the Performance and Stability of Amorphous Silicon Based Mid-Gap and Low-Gap Cells: Final Subcontract Report, 16 January 1998-15 October 2001  

DOE Green Energy (OSTI)

This report describes our experimental studies which have been concentrated in roughly five areas. Specifically: (1) We have examined a?Si:H grown very close to the microcrystalline phase boundary, so-called''edge material,'' to help understand why such material is more stable with respect to light-induced degradation; (2) We have also studied the electronic properties, and degradation characteristics of mixed phase material that is mostly a?Si:H, but which contains a significant microcrystalline component; (3) We have examined the electronic properties of high deposition rate material. These studies have included both moderately high deposition rate material (up to 6/s) produced by the PECVD growth method, and extremely high deposition rate material (up to 130/s) produced by the HWCVD growth method. (4) We have examined series of a-Si,Ge:H alloys from several sources. In one extensive series of studies we examined low Ge fraction alloys in an attempt to learn more about the fundamentals of degradation in general. In a couple other studies we evaluated the properties of a-Si,Ge:H alloys produced by methods we had not previously examined. (5) Finally, for three different types of samples we compared basic material properties with companion cell performance data. This was carried out in each case on series of samples for which one or more specific deposition parameters were varied systematically.

Cohen, J. D.

2002-07-01T23:59:59.000Z

235

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

DOE Green Energy (OSTI)

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.

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

2011-07-01T23:59:59.000Z

236

Chemical vapor deposition of amorphous semiconductor films. Semiannual report, 1 May 1984-31 October 1984  

DOE Green Energy (OSTI)

This report describes the results of research done by the Institute of Energy Conversion for the Solar Energy Research Institute in 1984 on high-efficiency, stable, amorphous silicon solar cells, fabricated by chemical vapor deposition (CVD) from disilane at high growth rates. The kinetics of CVD with higher order silanes were modelled for a tubular reactor with static substrates. A gas-phase reaction network was adopted, based on published silylene insertion and decomposition pathways. Mass balances for hydrogen and all saturated silanes through octasilane were derived. Boron-doped a-Si:H p-layers were deposited by CVD at 200/sup 0/ to 250/sup 0/C. Band gap and conductivity depended strongly on the diborane fraction in the feed gas, independent of substrate temperature. The effects of intrinsic layer deposition temperature and growth rate on material properties and device performance were studied. Cell parameters of p-i-n cells were correlated with i-layer deposition temperature and growth rate. Fill factor and short-circuit current depended on deposition conditions, while open-circuit voltage did not. Effects of diborane additions to the feed gas during i-layer deposition were studied. Experimental evidence and calculations indicate high resistance at the back contact.

Baron, B.N.; Rocheleau, R.E.; Hegedus, S.S.

1985-06-01T23:59:59.000Z

237

Interactions between radical growth precursors on plasma-deposited silicon thin-film surfaces  

SciTech Connect

We present a detailed analysis of the interactions between growth precursors, SiH{sub 3} radicals, on surfaces of silicon thin films. The analysis is based on a synergistic combination of density functional theory calculations on the hydrogen-terminated Si(001)-(2x1) surface and molecular-dynamics (MD) simulations of film growth on surfaces of MD-generated hydrogenated amorphous silicon (a-Si:H) thin films. In particular, the authors find that two interacting growth precursors may either form disilane (Si{sub 2}H{sub 6}) and desorb from the surface, or disproportionate, resulting in the formation of a surface dihydride (adsorbed SiH{sub 2} species) and gas-phase silane (SiH{sub 4}). The reaction barrier for disilane formation is found to be strongly dependent on the local chemical environment on the silicon surface and reduces (or vanishes) if one/both of the interacting precursors is/are in a ''fast diffusing state,'' i.e., attached to fivefold coordinated surface Si atoms. Finally, activation energy barriers in excess of 1 eV are obtained for two chemisorbed (i.e., bonded to a fourfold coordinated surface Si atom) SiH{sub 3} radicals. Activation energy barriers for disproportionation follow the same tendency, though, in most cases, higher barriers are obtained compared to disilane formation reactions starting from the same initial configuration. MD simulations confirm that disilane formation and disproportionation reactions also occur on a-Si:H growth surfaces, preferentially in configurations where at least one of the SiH{sub 3} radicals is in a ''diffusive state.'' Our results are in agreement with experimental observations and results of plasma process simulators showing that the primary source for disilane in low-power plasmas may be the substrate surface.

Bakos, Tamas; Valipa, Mayur S.; Maroudas, Dimitrios [Department of Chemical Engineering, University of Massachusetts, Amherst, Massachusetts 01003-3110 (United States)

2007-03-21T23:59:59.000Z

238

Low cost routes to high purity silicon and derivatives thereof  

DOE Patents (OSTI)

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).

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

2013-07-02T23:59:59.000Z

239

Implementation of a Comprehensive On-Line Closed-Loop Diagnostic System for Roll-to-Roll Amorphous Silicon Solar Cell Production: Final Subcontract Report, 23 April 2003 - 30 September 2006  

DOE Green Energy (OSTI)

This report summarizes Energy Conversion Devices' diagnostic systems that were developed in this program, as well as ECD's other major accomplishments. This report concentrates on work carried out in the final (third) phase of this program, beginning in the fall of 2004 and ending in the fall of 2006. ECD has developed a comprehensive in-situ diagnostic system that: Reduces the time between deposition in the a-Si machine and device characterization from about 200 h to about 1 h; The Photovoltaic Capacitive Diagnostic systems measure the open-circuit voltage and charging rate (a measure of the short-circuit current) and intra-cell series resistance for each cell in the triple-junction device prior to deposition of the top conductive-oxide coating in a subsequent deposition machine. These systems operate with an rms precision of about 0.03% and have operated for almost 4 years with no need for servicing of the electronics or for calibration; Spectrometers are used to measure the ZnO thickness of the backreflector, a Si thickness, and top conductive-oxide, coatings.

Ellison, T.

2007-05-01T23:59:59.000Z

240

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

DOE Green Energy (OSTI)

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.

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

2000-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Solar cell structure incorporating a novel single crystal silicon material  

DOE Patents (OSTI)

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.

Pankove, Jacques I. (Princeton, NJ); Wu, Chung P. (Trenton, NJ)

1983-01-01T23:59:59.000Z

242

Real Time Optics of the Growth of Textured Silicon Films in Photovoltaics: Final Technical Report, 1 August 1999--12 August 2002  

DOE Green Energy (OSTI)

Novel optical instruments, including single and dual rotating-compensator multichannel ellipsometers, have been designed and developed to probe the evolution of the microstructure, spectroscopic optical properties, and other materials characteristics during the fabrication and processing of individual thin films and thin-film structures used in photovoltaic devices. These instruments provide a foundation for next-generation process design/control and metrology in existing and future photovoltaics technologies. In this project, the materials system studied in the greatest detail was thin-film silicon, fabricated at low temperatures by plasma-enhanced chemical vapor deposition. Real-time measurements of such thin films by multichannel ellipsometry have established deposition phase diagrams that provide guiding principles for multistep fabrication of high-performance amorphous (a-Si:H) and microcrystalline (mc-Si:H) solar cells. Such phase diagrams have also served to disprove conventional wisdom in the fabrication of thin-film solar cell structures, thus avoiding future unproductive research efforts.

Collins, R. W.; Wronski, C. R.

2003-10-01T23:59:59.000Z

243

Holey Silicon as an Efficient Thermoelectric Material  

SciTech Connect

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.

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

2010-09-30T23:59:59.000Z

244

Thin Solid Films 430 (2003) 125129 0040-6090/03/$ -see front matter 2003 Elsevier Science B.V. All rights reserved.  

E-Print Network (OSTI)

for a-Si:H solar cell fabrication. In addition to photovoltaic applications, a-Si:H is also used of amorphous silicon (a-Si:H)-based photovoltaic devices, it is important to deposit high- quality a progress has been made in hydrogenated amorphous silicon (a-Si:H)-based thin film photovoltaic devices

Deng, Xunming

245

NREL Core Program (NCPV), Session: Film Silicon (Presentation)  

DOE Green Energy (OSTI)

This project supports the Solar America Initiative by: R and D that contributes to goal of grid parity by 2015; research to fill the industry R and D pipeline for next-generation low-cost scalable products; development of industry collaborative research; and improvement of NREL tools and capabilities for film silicon research. The project addresses both parts of film silicon roadmap: (1) amorphous-silicon-based thin film PV--amorphous and nanocrystalline materials, present '2nd generation' technology, 4% of world PV sales in 2007; (2) advanced R and D toward film crystal silicon--definition, large-grained or single-crystal silicon < 100 {micro}m thick; 3-8 year horizon; and goal of reaching 15% cells at area costs approaching thin films.

Branz, H. M.

2008-04-01T23:59:59.000Z

246

Amorphous Binary Alloy Structures  

NLE Websites -- All DOE Office Websites (Extended Search)

Hope Ishii, Sean Brennan and Arthur Bienenstock SSRL/SLAC 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 until the advent of X-ray synchrotron radiation, the X-ray radial distribution function (RDF) method was the most widely used approach for structure analysis of amorphous materials. The RDF is the probability of finding two electrons in a sample separated by a distance r, but with all

247

Experimental study of the factors governing the Staebler-Wronski photodegradation effect in a-Si:H solar cells. Annual subcontract report, 1 March 1994--31 March 1995  

DOE Green Energy (OSTI)

This report describes continuing experiments on electroluminescence (EL) and transient forward bias current (TFC) as well as photocurrent before and after light soaking for amorphous silicon (a-Si:H) devices. we continued our EL spectrum analysis on a p-i-n device with and without SiC:H buffer in the p-i interface. We started a program to study the Staebler-Wronski effect (SWE) in p-i-n solar cells made with and without H{sub 2} dilution, in collaboration with Solarex. In collaboration with L.E. McNeil, we studied the carrier recombination in p-i-n cells by both photoluminescence and EL. In collaboration with G.J. Adriaessens at Catholic University Leuven, Belgium, we studied TFC in p-i-n devices. In collaboration with Y. Wu, we studied the local Si-H bonding configuration in hot-wire samples by nuclear magnetic resonance. We concentrated on determining the factors controlling SWE, and on determining the correlation of EL data to the cell structure or preparation conditions, such as the effects of buffering and H{sub 2} dilution, by EL measurements.

Han, D.X.; McNeil, L.E.; Wang, K.D.; Yeh, C.N. [North Carolina Univ., Chapel Hill, NC (United States)

1995-08-01T23:59:59.000Z

248

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

DOE Green Energy (OSTI)

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.

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

2011-05-01T23:59:59.000Z

249

Distinct local electronic structure and magnetism for Mn in amorphous Si and Ge  

SciTech Connect

Transition metals such as Mn generally have large local moments in covalent semiconductors due to their partially filled d shells. However, Mn magnetization in group-IV semiconductors is more complicated than often recognized. Here we report a striking crossover from a quenched Mn moment (<0.1 {mu}{sub B}) in amorphous Si (a-Si) to a large distinct local Mn moment ({ge}3{mu}{sub B}) in amorphous Ge (a-Ge) over a wide range of Mn concentrations (0.005-0.20). Corresponding differences are observed in d-shell electronic structure and the sign of the Hall effect. Density-functional-theory calculations show distinct local structures, consistent with different atomic density measured for a-Si and a-Ge, respectively, and the Mn coordination number N{sub c} is found to be the key factor. Despite the amorphous structure, Mn in a-Si is in a relatively well-defined high coordination interstitial type site with broadened d bands, low moment, and electron (n-type) carriers, while Mn in a-Ge is in a low coordination substitutional type site with large local moment and holes (p-type) carriers. Moreover, the correlation between N{sub c} and the magnitude of the local moment is essentially independent of the matrix; the local Mn moments approach zero when N{sub c} > 7 for both a-Si and a-Ge.

Zeng, Li; Cao, J. X.; Helgren, E.; Karel, J.; Arenholz, E.; Ouyang, Lu; Smith, David J.; Wu, R. Q.; Hellman, F.

2010-06-01T23:59:59.000Z

250

Morphogenesis as an amorphous computation  

Science Conference Proceedings (OSTI)

In this paper, we present a programming language viewpoint for morphogenesis, the process of shape formation during embryological development. Specifically, we model morphogenesis as a self-organizing, self-repairing amorphous computation and describe ... Keywords: amorphous computing, emergent order, morphogenesis

Arnab Bhattacharyya

2006-05-01T23:59:59.000Z

251

Carbon-Silicon Core-Shell Nanowires as High Capacity Electrode for Lithium  

E-Print Network (OSTI)

Carbon-Silicon Core-Shell Nanowires as High Capacity Electrode for Lithium Ion Batteries Li lithium battery electrodes. Amorphous silicon was coated onto carbon nanofibers to form a core during lithium cycling and can function as a mechanical support and an efficient electron conducting

Cui, Yi

252

Silicon Atom Substitution Enhances Interchain Packing in a Thiophene-Based Polymer System  

SciTech Connect

A new silole-containing low bandgap polymer is synthesized by replacing the 5-position carbon of PCPDTBT with a silicon atom (PSBTBT). Through experiments and computational calculations, we show that the material properties, particular the packing of polymer chains, can be altered significantly. As a result, the polymer changes from amorphous to highly crystalline with the replacement of the silicon atom.

H Chen; J Hou; A Hayden; H Yang; K Houk; Y Yang

2011-12-31T23:59:59.000Z

253

ANNEALING BEHAVIOR OF HIGH PERMEABILITY AMORPHOUS ALLOYS  

E-Print Network (OSTI)

thermal stability for power transformer applications. Alloysinduction amorphous alloys in power transformers results in

Rabenberg, L.

2010-01-01T23:59:59.000Z

254

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

DOE Patents (OSTI)

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.

Pankove, Jacques I. (Princeton, NJ); Wu, Chung P. (Trenton, NJ)

1982-01-01T23:59:59.000Z

255

Research on the stability, electronic properties, and structure of a-Si:H and its alloys. Final subcontract report, 1 June 1991--31 May 1994  

DOE Green Energy (OSTI)

The authors research has focused on defect metastability and a-Si:C:H alloys. A new aspect of the metastability is the growing interest in the defect recovery process. They have continued to explore the role of hydrogen in the metastability and other properties of a-Si:H. This has led them to perform first principles calculations of Si-H bonding configurations. Another new feature of the metastability work is the study of the effects in hydrogenated poly-silicon. They have grown and studied the properties of a-Si:C:H alloys, particularly to observe the effects of hydrogen dilution. Finally they have also studied the recent defect relaxation phenomenon, and concluded that the effects arise from contact effects and are not an intrinsic effect in a-Si:H. Section A presents some recent models of metastability. Section B discusses the metastability and equilibration effects in hydrogenated polysilicon, studied because of it`s close similarity to a-Si:H. Section C describes results on a-Si:C:H alloys. Section D contains first principle LDA calculations of Si-H bonds and relates these results to the a-Si:H diffusion and metastability properties. In section E the authors report capacitance measurements aimed at exploring the recent results by Cohen et al who find an anomalous relaxation process from the trap filling kinetics of a DLTS experiment.

Jackson, W.B.; Johnson, N.; Nickel, N.; Schumm, G.; Street, R.A.; Thompson, R.; Tsai, C.C.; Van de Walle, C.; Walker, J. [Xerox Palo Alto Research Center, CA (United States)

1995-07-01T23:59:59.000Z

256

Amorphous metal alloy and composite  

DOE Patents (OSTI)

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.

Wang, Rong (Richland, WA); Merz, Martin D. (Richland, WA)

1985-01-01T23:59:59.000Z

257

Photon-controlled fabrication of amorphous superlattice structures using ArF (193 nm) excimer laser photolysis  

SciTech Connect

Pulsed ArF (193 nm) excimer laser photolysis of disilane, germane, and disilane-ammonia mixtures has been used to deposit amorphous superlattices containing silicon, germanium, and silicon nitride layers. Transmission electron microscope cross-section views demonstrate that structures having thin (5--25 nm) layers and sharp interlayer boundaries can be deposited at substrate temperatures below the pyrolytic threshold, entirely under laser photolytic control.

Lowndes, D.H.; Geohegan, D.B.; Eres, D.; Pennycook, S.J.; Mashburn, D.N.; Jellison G.E. Jr.

1988-05-30T23:59:59.000Z

258

ATP Project Brief - 00-00-7507  

Science Conference Proceedings (OSTI)

... has been traditionally used for years to apply layers of amorphous silicon (a-Si) thin films during the manufacture of photovoltaic (PV) solar cells. ...

259

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

SciTech Connect

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.

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

2013-09-03T23:59:59.000Z

260

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

SciTech Connect

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.

Farmer, Joseph C.; Wong, Frank M. G.; Haslam, Jeffery J.; Ji, Xiaoyan (Jane); 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.

2013-07-09T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Conducting polymer and hydrogenated amorphous silicon hybrid solar cells  

E-Print Network (OSTI)

-methylpyrrolidone, and isopropanol.14 The modified PEDOT:PSS was spin cast at 800 rpm onto a 25 mm 25 mm indium-tin-oxide ITO coated State University, Tempe, Arizona 85287 Qi Wang,b Sean E. Shaheen, and David S. Ginley National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 Eric A. Schiff Department of Physics, Syracuse

Schiff, Eric A.

262

The specific heat of pure and hydrogenated amorphous silicon  

E-Print Network (OSTI)

thin film sample and a weak thermal link between the samplepreserving the weak thermal link through the membrane

Queen, Daniel Robert

2011-01-01T23:59:59.000Z

263

Structure of Pentacene Monolayers on Amorphous Silicon Oxide...  

NLE Websites -- All DOE Office Websites (Extended Search)

and potential applications in low-cost electronics such as organic light emitting diode (OLED) displays, thin film transistors and related applications (e.g. TFT...

264

Amorphous Metal Transformer: Next Steps  

Science Conference Proceedings (OSTI)

Amorphous-metal transformers were developed through EPRI in the early 1980's. Over the next 15 years, US electric utilities bought and installed over 500,000 units and had satisfactory field experience. The demand for this product disappeared in North America late in the 1990's as deregulation set-in. Globally, this product has been in use, and its acceptance has been increasing. This paper describes the current state of amorphous transformer activities globally. An analysis using US Department of Energy...

2009-07-31T23:59:59.000Z

265

Near-Field Microscopy Through a SiC Superlens  

E-Print Network (OSTI)

Near-Field Microscopy Through a SiC Superlens Thomas Taubner,1 * Dmitriy Korobkin,2 Yaroslav of the slab (4­6). In our experiment, we placed a SiC superlens (7) between the scan- ning probe tip-crystalline SiC membrane coated on both sides with 220-nm-thick SiO2 layers (7). The two surfaces of the sandwich

Shvets, Gennady

266

Amorphous Calcium Phosphate-Based Bioactive Polymeric ...  

Science Conference Proceedings (OSTI)

... Glass ionomers/resin modified Release of fluoride ions from ionomers/ compomers fluoride-containing filler Amorphous calcium phosphate Release ...

2003-07-02T23:59:59.000Z

267

Atomic Scale Deformation Mechanisms of Amorphous Polyethylene ...  

Science Conference Proceedings (OSTI)

Atomic Scale Deformation Mechanisms of Amorphous Polyethylene under Tensile Loading Atomistic Predictions of Age Hardening in Al-Cu Alloys.

268

Silicon nucleation and film evolution on silicon dioxide using disilane: Rapid thermal chemical vapor deposition of very smooth silicon at high deposition rates  

SciTech Connect

An investigation of Si{sub 2}H{sub 6} and H{sub 2} for rapid thermal chemical vapor deposition (RTCVD) of silicon on SiO{sub 2} has been performed at temperatures ranging from 590 to 900 C and pressures ranging from 0.1 to 1.5 Torr. Deposition at 590 C yields amorphous silicon films with the corresponding ultrasmooth surface with a deposition rate of 68 nm/min. Cross-sectional transmission electron microscopy of a sample deposited at 625 C and 1 Torr reveals a bilayer structure which is amorphous at the growth surface and crystallized at the oxide interface. Higher temperatures yield polycrystalline films where the surface roughness depends strongly on both deposition pressure and temperature. Silane-based amorphous silicon deposition in conventional systems yields the expected ultrasmooth surfaces, but at greatly reduced deposition rates unsuitable for single-wafer processing. However, disilane, over the process window considered here, yields growth rates high enough to be appropriate for single-wafer manufacturing, thus providing a viable means for deposition of very smooth silicon films on SiO{sub 2} in a single-wafer environment.

Violette, K.E.; Oeztuerk, M.C.; Christensen, K.N.; Maher, D.M. [North Carolina State Univ., Raleigh, NC (United States)

1996-02-01T23:59:59.000Z

269

Silicon Microrefrigerator  

E-Print Network (OSTI)

We fabricated a silicon microrefrigerator on a 500-mu m-thick substrate with the standard integrated circuit (IC) fabrication process. The cooler achieves a maximum cooling of 1 degrees C below ambient at room temperature. Simulations show that the cooling power density for a 40 x 40 mu m(2) device exceeds 500 W/cm(2). The unique three-dimensional (3-D) geometry, current and heat spreading, different from conventional one-dimensional (1-D) thermoelectric device, contribute to this large cooling power density. A 3-D finite element electrothermal model is used to analyze non-ideal factors inside the device and predict its limits. The simulation results show that in the ideal situation, with low contact resistance, bulk silicon with 3-D geometry could cool similar to 20 degrees C with a cooling power density of 1000 W/cm(2) despite the low thermoelectric figure-of-merit (ZT) of the material. The large cooling power density is due to the geometry dependent heat and current spreading in the device. The non-uniformity of current and Joule heating inside the substrate also contributes to the maximum cooling of silicon microrefrigerator, exceeding 30 % limit given in one-dimensional thermoelectric theory Delta T-max = 0.5ZT(c)(2) where T-c is the cold side temperature. These devices can be used c to remove hot spots

Y Zhang; G H. Zeng; A Shakouri; Yan Zhang; Gehong Zeng; Ali Shakouri

2006-01-01T23:59:59.000Z

270

Pulsed energy synthesis and doping of silicon carbide  

DOE Patents (OSTI)

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.

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

1995-06-20T23:59:59.000Z

271

Pulsed energy synthesis and doping of silicon carbide  

DOE Patents (OSTI)

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.

Truher, Joel B. (San Rafael, CA); Kaschmitter, James L. (Pleasanton, CA); Thompson, Jesse B. (Brentwood, CA); Sigmon, Thomas W. (Beaverton, OR)

1995-01-01T23:59:59.000Z

272

Optical modeling of a-Si solar cells  

DOE Green Energy (OSTI)

The authors describe applications of PV Optics to analyze the behavior of a metallic back-reflector on an a-Si solar cell. The calculated results from PV Optics agree well with the measured data on solar cells. Several unexpected results obtained from these calculations are qualitatively explained.

Sopori, B.; Madjdpour, J.; Zhang, Y.; Chen, W.; Guha, S.; Yang, J.; Banerjee, A.; Hegedus, S.

1999-11-04T23:59:59.000Z

273

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

DOE Green Energy (OSTI)

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.

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

2009-06-08T23:59:59.000Z

274

Method of producing amorphous thin films  

DOE Patents (OSTI)

This invention dicloses a method for sintering particulate material (such as silica) with a laser beam to produce amorphous optical thin films on substrates.

Brusasco, R.M.

1991-12-31T23:59:59.000Z

275

Amorphous and nanocrystalline Mg2Si thin-film electrodes  

NLE Websites -- All DOE Office Websites (Extended Search)

Contact Us Department Contacts Media Contacts Amorphous and nanocrystalline Mg2Si thin-film electrodes Title Amorphous and nanocrystalline Mg2Si thin-film electrodes...

276

Hybrid silicon nanocrystal silicon nitride dynamic random access memory  

Science Conference Proceedings (OSTI)

This paper introduces a silicon nanocrystal-silicon nitride hybrid single transistor cell for potential dynamic RAM (DRAM) applications that stores charge in silicon nanocrystals or a silicon nitride charge trapping layer or both. The memory operates ...

R. F. Steimle; M. Sadd; R. Muralidhar; Rajesh Rao; B. Hradsky; S. Straub; B. E. White, Jr.

2003-12-01T23:59:59.000Z

277

Properties of Amorphous Carbon Microspheres Synthesised by Palm Oil-CVD Method  

Science Conference Proceedings (OSTI)

Amorphous carbon microspheres were synthesized using a dual-furnace chemical vapour deposition method at 800-1000 deg. C. Palm oil-based cooking oil (PO) and zinc nitrate solution was used as a carbon source and catalyst precursor, respectively with PO to zinc nitrate ratio of 30:20 (v/v) and a silicon wafer as the sample target. Regular microsphere shape of the amorphous carbons was obtained and a uniform microsphere structure improved as the carbonization temperature increased from 800 to 1000 deg. C. At 800 deg. C, no regular microspheres were formed but more uniform structure is observed at 900 deg. C. Generally the microspheres size is uniform when the heating temperature was increased to 1000 deg. C, but the presence of mixed sizes can still be observed. X-ray diffraction patterns show the presence of oxide of carbon, ZnO phase together with Zn oxalate phase. Raman spectra show two broad peaks characteristic to amorphous carbon at 1344 and 1582 cm{sup -1} for the D and G bands, respectively. These bands become more prominent as the preparation temperature increased from 800 to 1000 deg. C. This is in agreement with the formation of amorphous carbon microspheres as shown by the FESEM study and other Zn-based phases as a result of the oxidation process of the palm oil as the carbon source and the zinc nitrate as the catalyst precursor, respectively.

Zobir, S. A. M. [Faculty of Applied Sciences, (UiTM), 40450 Shah Alam, Selangor (Malaysia); Nano-SciTech Centre, (UiTM), 40450 Shah Alam, Selangor (Malaysia); Zainal, Z. [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400UPM, Serdang, Selangor (Malaysia); Sarijo, S. H. [Faculty of Applied Sciences, (UiTM), 40450 Shah Alam, Selangor (Malaysia); Institute of Science, Universiti Teknologi MARA Malaysia, (UiTM), 40450 Shah Alam, Selangor (Malaysia); Rusop, M. [Nano-SciTech Centre, (UiTM), 40450 Shah Alam, Selangor (Malaysia); Institute of Science, Universiti Teknologi MARA Malaysia, (UiTM), 40450 Shah Alam, Selangor (Malaysia)

2011-03-30T23:59:59.000Z

278

Photovoltaic devices using a-Si:H from higher order silanes. Semiannual report, 1 September 1983-29 February 1984  

DOE Green Energy (OSTI)

This report summarizes research performed during a six-month period on hydrogenated amorphous silicon, prepared by chemical vapor deposition using flow methods rather than a static method in order to deposit from a time-invariant gas phase chemistry. Both low-pressure and atmospheric-pressure systems were employed. The feedstock gases were electronic-grade higher order silanes (principally disilane) manufactured by silent electric discharge. Because of the historically poor performance of CVD p layers in p-i-n devices, an effort was made to develop a higher quality p layer. Both silane/diborane and disilane/diborane mixtures were investigated. Using disilane/diborane mixtures at low pressures and very low temperatures (200/sup 0/C) significantly improved LPCVD p layers. P-i-n devices employing these p layers exhibited open-circuit voltages up to 723 mV.

Delahoy, A.E.

1984-10-01T23:59:59.000Z

279

X-ray photoelectron spectroscopy and structural analysis of amorphous SiO{sub x}N{sub y} films deposited at low temperatures  

Science Conference Proceedings (OSTI)

We establish, using a tetrahedral model, the bonding properties of amorphous silicon oxynitride (a-SiO{sub x}N{sub y}) films deposited at low temperatures (LTs) by electron-cyclotron resonance chemical-vapor deposition (ECRCVD) on several substrates and under various conditions of gas flows and total gas pressure in a dilute mixture of SiH{sub 4}+N{sub 2} in Ar. The atomic percentage of each tetrahedral unit incorporated in the film network is calculated from the deconvolution of the high-resolution x-ray photoelectron spectroscopy (XPS) spectra in the Si 2p{sub 3/2} region and corroborated by the results obtained from both survey scans and the high-resolution XPS spectra in the N 1s region. The Si{sub 3}N{sub 4} phase is the most important one and the only bonding unit which is incorporated in all our LT ECRCVD SiO{sub x}N{sub y} films. The incorporation of all the other component tetrahedrons depends strongly on growth conditions. The threshold values of the N/Si atomic ratio for which intrinsic defects, such as Si-Si bonds, are not incorporated in the network depend on the O/Si ratio incorporated in the films, mainly due to the competition between oxygen and nitrogen atoms in their reaction with silicon dangling bonds. The effect of the total gas pressure on the atomic percentages of the oxidation states present in the LT ECRCVD SiO{sub x}N{sub y} films is qualitatively similar to the effect of the ion bombarding energy or the plasma density. O-N bonds are present only in samples having high amount of oxygen and nitrogen in their networks. For these films, our results show unambiguously the presence of the N-Si{sub 2}O tetrahedron and suggest that N-Si{sub 3-{nu}}O{sub {nu}} tetrahedrons with {nu}{>=}2 are not incorporated in their networks. A correlation is observed between the N-Si{sub 2}O and the Si-O{sub 3}(ON) tetrahedrons whose component peak is localized at (104.0{+-}0.2) eV in the Si 2p{sub 3/2} region of the XPS data, which suggests that both bonding units coexist in these films as some sort of complex bonding configuration.

Cova, P.; Poulin, S.; Masut, R.A. [Departmento de Fisica, Laboratorio de Simulacion de Dispositivos Semiconductores, Universidad de Oriente, Apartado 124, Cumana 6101, Sucre (Venezuela); Regroupement Quebecois sur les Materiaux de Pointe (RQMP) and Departement de Genie Physique, Ecole Polytechnique, C.P. 6079, succ. Centre-ville, Montreal, Quebec H3C 3A7 (Canada)

2005-11-01T23:59:59.000Z

280

multicrystalline silicon  

DOE Green Energy (OSTI)

This manuscript concerns the application of infrared birefringence imaging (IBI) to quantify macroscopic and microscopic internal stresses in multicrystalline silicon (mc-Si) solar cell materials. We review progress to date, and advance four closely related topics. (1) We present a method to decouple macroscopic thermally-induced residual stresses and microscopic bulk defect related stresses. In contrast to previous reports, thermally-induced residual stresses in wafer-sized samples are generally found to be less than 5 MPa, while defect-related stresses can be several times larger. (2) We describe the unique IR birefringence signatures, including stress magnitudes and directions, of common microdefects in mc-Si solar cell materials including: {beta}-SiC and {beta}-Si{sub 3}N{sub 4} microdefects, twin bands, nontwin grain boundaries, and dislocation bands. In certain defects, local stresses up to 40 MPa can be present. (3) We relate observed stresses to other topics of interest in solar cell manufacturing, including transition metal precipitation, wafer mechanical strength, and minority carrier lifetime. (4) We discuss the potential of IBI as a quality-control technique in industrial solar cell manufacturing.

Ganapati, Vidya; Schoenfelder, Stephan; Castellanos, Sergio; Oener, Sebastian; Koepge, Ringo; Sampson, Aaron; Marcus, Matthew A.; Lai, Barry; Morhenn, Humphrey; Hahn, Giso; Bagdahn, Joerg; Buonassisi1, Tonio

2010-05-05T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Structural Ordering and its Correlation to the Optoelectronic Properties of a-Si:H Films  

DOE Green Energy (OSTI)

Magnetic susceptibility was suggested theoretically to be sensitive to the overall structural order of a-Si:H and is measured precisely for various a-Si:H thin films using a new technique.

Baugh, J.; Han, D.; Kleinhammes, A.; Wang, Q.; Wu, Y.

2000-01-01T23:59:59.000Z

282

Advanced silicon photonic modulators  

E-Print Network (OSTI)

Various electrical and optical schemes used in Mach-Zehnder (MZ) silicon plasma dispersion effect modulators are explored. A rib waveguide reverse biased silicon diode modulator is designed, tested and found to operate at ...

Sorace, Cheryl M

2010-01-01T23:59:59.000Z

283

Crystalline Silicon Photovolatic Cells  

Energy.gov (U.S. Department of Energy (DOE))

Crystalline silicon cells are made of silicon atoms connected to one another to form a crystal lattice. This lattice comprises the solid material that forms the photovoltaic (PV) cell's...

284

Silicon solar cell assembly  

DOE Patents (OSTI)

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.

Burgess, Edward L. (Albuquerque, NM); Nasby, Robert D. (Albuquerque, NM); Schueler, Donald G. (Albuquerque, NM)

1979-01-01T23:59:59.000Z

285

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

DOE Patents (OSTI)

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.

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

1982-03-30T23:59:59.000Z

286

Solar Cell Silicon  

Science Conference Proceedings (OSTI)

Jul 31, 2011 ... About this Symposium. Meeting, 2012 TMS Annual Meeting & Exhibition. Symposium, Solar Cell Silicon. Sponsorship, The Minerals, Metals...

287

Electrodeposition of molten silicon  

DOE Patents (OSTI)

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.

De Mattei, Robert C. (Sunnyvale, CA); Elwell, Dennis (Palo Alto, CA); Feigelson, Robert S. (Saratoga, CA)

1981-01-01T23:59:59.000Z

288

SURVIVAL OF AMORPHOUS WATER ICE ON CENTAURS  

Science Conference Proceedings (OSTI)

Centaurs are believed to be Kuiper Belt objects in transition between Jupiter and Neptune before possibly becoming Jupiter family comets. Some indirect observational evidence is consistent with the presence of amorphous water ice in Centaurs. Some of them also display a cometary activity, probably triggered by the crystallization of the amorphous water ice, as suggested by Jewitt and this work. Indeed, we investigate the survival of amorphous water ice against crystallization, using a fully three-dimensional thermal evolution model. Simulations are performed for varying heliocentric distances and obliquities. They suggest that crystallization can be triggered as far as 16 AU, though amorphous ice can survive beyond 10 AU. The phase transition is an efficient source of outgassing up to 10-12 AU, which is broadly consistent with the observations of the active Centaurs. The most extreme case is 167P/CINEOS, which barely crystallizes in our simulations. However, amorphous ice can be preserved inside Centaurs in many heliocentric distance-obliquity combinations, below a {approx}5-10 m crystallized crust. We also find that outgassing due to crystallization cannot be sustained for a time longer than 10{sup 4}-10{sup 4} years, leading to the hypothesis that active Centaurs might have recently suffered from orbital changes. This could be supported by both observations (although limited) and dynamical studies.

Guilbert-Lepoutre, Aurelie, E-mail: aguilbert@ucla.edu [Department of Earth and Space Sciences, UCLA, Los Angeles, CA 90095 (United States)

2012-10-01T23:59:59.000Z

289

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

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}).

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)

2012-01-15T23:59:59.000Z

290

Solar Cell Silicon  

Science Conference Proceedings (OSTI)

... continued and costs have been cut dramatically along the production value chain. The most important feedstock for crystalline solar cells is high purity silicon .

291

Silicon Refining II  

Science Conference Proceedings (OSTI)

Research on the Forecast Model of the Boron Removal from Metallurgical Grade ... sufficient level of silicon quality together with relatively low production cost.

292

Nonoriented Silicon Steels  

Science Conference Proceedings (OSTI)

Table 2 Silicon contents, mass densities, and applications of electrical steel sheet and strip...generally used in distribution transformers. Energy savings improve with

293

Production Methods for Amorphous Alloy for Transformer Cores  

Science Conference Proceedings (OSTI)

Transmission and distribution system transformers made of ferromagnetic amorphous metals have far lower core losses than conventional transformers. A pilot plant demonstrated production of these amorphous alloys; a large-scale plant has since been constructed for commercial production.

1993-07-01T23:59:59.000Z

294

The Private Life of Electrons in Amorphous Insulators  

Science Conference Proceedings (OSTI)

... The Private Life of Electrons in Amorphous Insulators. Since the twenties, it has been known that the stationary electron ...

295

Amorphous Materials: Common Issues within Science and Technology  

Science Conference Proceedings (OSTI)

About this Symposium. Meeting, Materials Science & Technology 2013. Symposium, Amorphous Materials: Common Issues within Science and Technology.

296

Thermally Oxidized Silicon  

NLE Websites -- All DOE Office Websites (Extended Search)

Anneli Munkholm (Lumileds Lighting) and Sean Brennan (SSRL) 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 lattice. The outline of four silicon unit cells is shown in black, whereas the outline of four expanded lattice cells in the oxide is shown in blue One of the most studied devices of modern technology is the field-effect transistor, which is the basis for most integrated circuits. At its heart

297

Direct observation of grain growth from molten silicon formed by micro-thermal-plasma-jet irradiation  

Science Conference Proceedings (OSTI)

Phase transformation of amorphous-silicon during millisecond annealing using micro-thermal-plasma-jet irradiation was directly observed using a high-speed camera with microsecond time resolution. An oval-shaped molten-silicon region adjacent to the solid phase crystallization region was clearly observed, followed by lateral large grain growth perpendicular to a liquid-solid interface. Furthermore, leading wave crystallization (LWC), which showed intermittent explosive crystallization, was discovered in front of the moving molten region. The growth mechanism of LWC has been investigated on the basis of numerical simulation implementing explosive movement of a thin liquid layer driven by released latent heat diffusion in a lateral direction.

Hayashi, Shohei; Fujita, Yuji; Kamikura, Takahiro; Sakaike, Kohei; Akazawa, Muneki; Ikeda, Mitsuhisa; Hanafusa, Hiroaki; Higashi, Seiichiro [Department of Semiconductor Electronics and Integration Science, Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530 (Japan)

2012-10-22T23:59:59.000Z

298

Phase diagram of amorphous solid water: Low-density, high-density, and very-high-density amorphous ices  

E-Print Network (OSTI)

for the understanding of the transformation between the different amorphous ices and the two hypothesized phasesPhase diagram of amorphous solid water: Low-density, high-density, and very-high-density amorphous ices Nicolas Giovambattista,1,2 H. Eugene Stanley,2 and Francesco Sciortino3 1 Department of Chemical

Sciortino, Francesco

299

Polymorphism of the glass former ethanol confined in mesoporous silicon  

E-Print Network (OSTI)

X-ray diffraction patterns of ethanol confined in parallel-aligned channels of approx. 10 nm diameter and 50 micrometer length in mesoporous silicon have been recorded as a function of filling fraction, temperature and for varying cooling and heating rates. A sorption isotherm, recorded in the liquid state, indicates a three monolayer thick, strongly adsorbed wall layer and a capillary condensed fraction of molecules in the pore center. Though the strongly adsorbed film remains in an amorphous state for the entire temperature range investigated, the capillary condensed molecules reproduce the polymorphism of bulk solid ethanol, that is the formation of either crystalline or glass-like states as a function of cooling rate. The critical rate necessary to achieve a vitrification in the mesopores is, however, at least two orders of magnitude smaller than in the bulk state. This finding can be traced both to pure geometrical constraints and quenched disorder effects, characteristic of confinement in mesoporous silicon.

Anke Henschel; Klaus Knorr; Patrick Huber

2010-05-12T23:59:59.000Z

300

Solar cells utilizing pulsed-energy crystallized microcrystalline/polycrystalline silicon  

DOE Patents (OSTI)

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.

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

1995-10-10T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Solar cells utilizing pulsed-energy crystallized microcrystalline/polycrystalline silicon  

DOE Patents (OSTI)

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.

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

1995-01-01T23:59:59.000Z

302

Investigation of tilted dose kernels for portal dose prediction in a-Si electronic portal imagers  

SciTech Connect

The effect of beam divergence on dose calculation via Monte Carlo generated dose kernels was investigated in an amorphous silicon electronic portal imaging device (EPID). The flat-panel detector was simulated in EGSnrc with an additional 3.0 cm water buildup. The model included details of the detector's imaging cassette and the front cover upstream of it. To approximate the effect of the EPID's rear housing, a 2.1 cm air gap and 1.0 cm water slab were introduced into the simulation as equivalent backscatter material. Dose kernels were generated with an incident pencil beam of monoenergetic photons of energy 0.1, 2, 6, and 18 MeV. The orientation of the incident pencil beam was varied from 0 deg. to 14 deg. in 2 deg. increments. Dose was scored in the phosphor layer of the detector in both cylindrical (at 0 deg. ) and Cartesian (at 0 deg. -14 deg.) geometries. To reduce statistical fluctuations in the Cartesian geometry simulations at large radial distances from the incident pencil beam, the voxels were first averaged bilaterally about the pencil beam and then combined into concentric square rings of voxels. Profiles of the EPID dose kernels displayed increasing asymmetry with increasing angle and energy. A comparison of the superposition (tilted kernels) and convolution (parallel kernels) dose calculation methods via the {chi}-comparison test (a derivative of the {gamma}-evaluation) in worst-case-scenario geometries demonstrated an agreement between the two methods within 0.0784 cm (one pixel width) distance-to-agreement and up to a 1.8% dose difference. More clinically typical field sizes and source-to-detector distances were also tested, yielding at most a 1.0% dose difference and the same distance-to-agreement. Therefore, the assumption of parallel dose kernels has less than a 1.8% dosimetric effect in extreme cases and less than a 1.0% dosimetric effect in most clinically relevant situations and should be suitable for most clinical dosimetric applications. The resulting time difference for the parallel kernel assumption versus the tilted kernels was 10.5 s vs 18 h (a factor of approximately 6000), dependent on existing hardware and software details.

Chytyk, K.; McCurdy, B. M. C. [Division of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9, Canada and Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Division of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada) and Department of Radiology, University of Manitoba, Winnipeg, Manitoba R3A 1R9 (Canada)

2006-09-15T23:59:59.000Z

303

Electrical detection of spin echoes for phosphorus donors in silicon  

E-Print Network (OSTI)

The electrical detection of spin echoes via echo tomography is used to observe decoherence processes associated with the electrical readout of the spin state of phosphorus donor electrons in silicon near a SiO$_2$ interface. Using the Carr-Purcell pulse sequence, an echo decay with a time constant of $1.7\\pm0.2 \\rm{\\mu s}$ is observed, in good agreement with theoretical modeling of the interaction between donors and paramagnetic interface states. Electrical spin echo tomography thus can be used to study the spin dynamics in realistic spin qubit devices for quantum information processing.

Hans Huebl; Felix Hoehne; Benno Grolik; Andre R. Stegner; Martin Stutzmann; Martin S. Brandt

2007-12-02T23:59:59.000Z

304

Nanostructure of a-Si:H and related alloys by small-angle scattering of neutrons and X-rays: Annual technical progress report: May 22, 1998 -- May 21, 1999  

DOE Green Energy (OSTI)

This report describes work being performed to provide details of the microstructure in high-quality hydrogenated amorphous silicon and related alloys on the nanometer scale. The materials under study are being prepared by state-of-the-art deposition methods, as well as by new and emerging deposition techniques. The purpose is to establish the role of nanostructural features in controlling opto-electronic and photovoltaic properties. The approach centers around the use of the uncommon technique of small-angle scattering of both X-rays (SAXS) and neutrons (SANS). SAXS has already been established as highly sensitive to microvoids and columnar-like microstructure. A major goal of this research is to establish the sensitivity of SANS to the hydrogen nanostructure. Conventional X-ray diffraction techniques are being used to examine medium-range order and microcrystallinity, particularly near the boundary between amorphous and microcrystalline material.

Williamson, D. L.

1999-12-21T23:59:59.000Z

305

Enabling Thin Silicon Solar Cell Technology  

NLE Websites -- All DOE Office Websites (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...

306

Experimental and Molecular Simulation Studies of Silicon ...  

Science Conference Proceedings (OSTI)

Symposium, Solar Cell Silicon ... On the Segregation of Impurities in Solar Silicon ... Silicon PV Wafers: Correlation of Mechanical Properties and Crack...

307

Silicon Production and Refining  

Science Conference Proceedings (OSTI)

Mar 6, 2013 ... The photovoltaic (PV) industry is in rapid growth and a large supply of solar grade silicon (SoG-Si) feedstock must be provided to response the...

308

Silicon nanocrystal memories  

Science Conference Proceedings (OSTI)

In this paper, we present an overview of memory structures fabricated by our group by using silicon nanocrystals as storage nodes. These devices show promising characteristics as candidates for future deep-submicron non-volatile memories.

S. Lombardo; B. De Salvo; C. Gerardi; T. Baron

2004-05-01T23:59:59.000Z

309

Synthesis of new amorphous metallic spin glasses  

DOE Patents (OSTI)

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.

Haushalter, Robert C. (Clinton, NJ)

1986-01-01T23:59:59.000Z

310

Synthesis of new amorphous metallic spin glasses  

DOE Patents (OSTI)

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.

Haushalter, R.C.

1985-02-11T23:59:59.000Z

311

Synthesis of new amorphous metallic spin glasses  

DOE Patents (OSTI)

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.

Haushalter, Robert C. (Clinton, NJ)

1988-01-01T23:59:59.000Z

312

Experimental investigation of size effect on thermal conductivity for ultra-thin amorphous poly(methyl methacrylate) (PMMA) films  

E-Print Network (OSTI)

An investigation was conducted to determine whether a size effect phenomenon for one particular thermophysical property, thermal conductivity, actually exists for amorphous poly(methyl methacrylate) (PMMA) films with thicknesses ranging from 40 nm to 2 ?m. This was done by using a non-contact, non-invasive, in-situ Transient Thermo-Reflectance (TTR) laser based technique. The results demonstrated that the intrinsic thermal conductivity of a 40 nm PMMA film deposited on native oxide of silicon increases by a factor of three over bulk PMMA values, and a distinct increase in the thermal conductivity of PMMA film was observed in ultra-thin (sub 100 nm) films. This confirmed the importance of film thickness for the through-plane thermal conductivity value of PMMA film on native oxide of silicon.

Kim, Ick Chan

2007-05-01T23:59:59.000Z

313

Silicon web process development  

DOE Green Energy (OSTI)

Silicon dendritic web is a ribbon form of silicon produced from the melt without die shaping, and capable of fabrication into solar cells with greater than 15% AM1 conversion efficiency. This quarterly report describes the work carried out during the period April to June 1980, as part of Phase III of a DOE/JPL-sponsored effort to develop silicon web process technology compatible with the national goals for low cost photovoltaic output power. We have successfully demonstrated eight hours of silicon web growth with closed loop melt level control, a key contract milestone. The result was achieved using a feedback system in which the change in output from a laser melt level sensor was used to control the rate at which silicon pellets were fed to replace the material frozen into web crystal. The melt level was controlled to about +- 0.1mm, well within the range required for stable long term web growth. This is an important step toward the development of a fully automated silicon web growth machine. A second major highlight of this quarter was the completion of an engineering design for a semi-automated web growth machine embodying all the desired features developed so far as part of this program (including e.g. melt replenishment, level sensing and control) as well as some system simplifications. The completed design will serve as a basis for complete system automation.

Duncan, C.S.; Seidensticker, R.G.; McHugh, J.P.; Skutch, M.E.; Hopkins, R.H.

1980-07-15T23:59:59.000Z

314

Silicon Wafers for the Mesoscopic Era  

Science Conference Proceedings (OSTI)

... Silicon: Surface COPS - Capacitor Defect ... CoO - Wafer Diameter Expand interaction with Super Silicon Initiative and maintain ...

315

Research on the stability, electronic properties, and structure of a-Si:H and its alloys  

DOE Green Energy (OSTI)

Objective is to obtain a comprehensive understanding of structure and electronic properties of a-Si:H as they apply to solar cells. First observations were of light enhancement and field suppression of H diffusion in a-Si:H. Theoretical studies were made of hydrogen density of states distribution and its relation to defect metastability. Reduced density of light induced defect is observed in a-Si:H deposited in a remote hydrogen plasma reactor at 400 C. Kinetics of metastable defect creation using forward bias in a p-i-n diode to induce defects were studied and compared to light-induced defect creation in the same devices. Studies were made of transport at high electric field and low temperature. Detailed studies were made of kinetics of dopant metastability in n-type and p-type a-Si:H.

Street, R.A.; Jackson, W.B.; Johnson, N.; Nebel, C.; Hack, M.; Santos, P.; Thompson, R.; Tsai, C.C.; Walker, J. (Xerox Palo Alto Research Center, CA (United States))

1992-12-01T23:59:59.000Z

316

Fabrication of Amorphous Alloy Surface Composites by High ... - TMS  

Science Conference Proceedings (OSTI)

Jun 1, 2007 ... Fabrication of Amorphous Alloy Surface Composites by High-Energy Electron- Beam Irradiation by K. Lee, S. Lee, and N.J. Kim...

317

Residual Stress Measurement in Amorphous Materials by the Micro ...  

Science Conference Proceedings (OSTI)

... minimal human guidance in its operation. We demonstrate the influence of particular sources of errors on RS estimates in homogeneous amorphous materials...

318

Localized Phase Transformation in Amorphous Fe-Si-B Ribbons ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Fe-based amorphous alloys are used in modern transformers to reduce the core losses as they exhibit excellent permeability and increased...

319

Spark Plasma Sintering of Amorphous Coatings on Metallic Substrate  

Science Conference Proceedings (OSTI)

In the present work, we will discuss the results of deposition of amorphous coatings on metallic substrates using spark plasma sintering method. The influence of...

320

New Atomization Technology for Fine Amorphous Alloy Powder ...  

Science Conference Proceedings (OSTI)

However, the present conventional powder-making processes (gas and water atomization) seem difficult to reduce the price of amorphous alloy powders.

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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321

AMORPHOUS THIN FILMS CONSISTING OF TERNARY MgZnCa ...  

Science Conference Proceedings (OSTI)

Jul 20, 2012 ... AMORPHOUS THIN FILMS CONSISTING OF TERNARY MgZnCa-ALLOYS by K. Schlter, C. Zamponi, U. Schrmann, N. Hort, L. Kienle, K.U....

322

Akros Silicon | Open Energy Information  

Open Energy Info (EERE)

Akros Silicon Akros Silicon Jump to: navigation, search Name Akros Silicon Place Folsom, California Zip 95630 Product Akros Silicon specilizes in fabless semicondutors used for Power Over Ethernet, networks, and broadband. References Akros Silicon[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Akros Silicon is a company located in Folsom, California . References ↑ "Akros Silicon" Retrieved from "http://en.openei.org/w/index.php?title=Akros_Silicon&oldid=341960" Categories: Clean Energy Organizations Companies Organizations Stubs What links here Related changes Special pages Printable version Permanent link Browse properties 429 Throttled (bot load) Error 429 Throttled (bot load)

323

It's Elemental - The Element Silicon  

NLE Websites -- All DOE Office Websites (Extended Search)

Number: 3 Group Number: 14 Group Name: none What's in a name? From the Latin word for flint, silex. Say what? Silicon is pronounced as SIL-ee-ken. History and Uses: Silicon was...

324

CORROSION RESISTANCE OF STRUCTURAL AMORPHOUS METAL  

SciTech Connect

Corrosion costs the Department of Defense billions of dollars every year, with an immense quantity of material in various structures undergoing corrosion. For example, in addition to fluid and seawater piping, ballast tanks, and propulsions systems, approximately 345 million square feet of structure aboard naval ships and crafts require costly corrosion control measures. The use of advanced corrosion-resistant materials to prevent the continuous degradation of this massive surface area would be extremely beneficial. The potential advantages of amorphous metals have been recognized for some time [Latanison 1985]. Iron-based corrosion-resistant, amorphous-metal coatings under development may prove important for maritime applications [Farmer et al. 2005]. Such materials could also be used to coat the entire outer surface of containers for the transportation and long-term storage of spent nuclear fuel, or to protect welds and heat affected zones, thereby preventing exposure to environments that might cause stress corrosion cracking [Farmer et al. 1991, 2000a, 2000b]. In the future, it may be possible to substitute such high-performance iron-based materials for more-expensive nickel-based alloys, thereby enabling cost savings in a wide variety of industrial applications. It should be noted that thermal-spray ceramic coatings have also been investigated for such applications [Haslam et al. 2005]. This report focuses on the corrosion resistance of a yttrium-containing amorphous metal, SAM1651. SAM1651 has a glass transition temperature of {approx}584 C, a recrystallization temperature of {approx}653 C, and a melting point of {approx}1121 C. The measured critical cooling rate for SAM1651 is {le} 80 K per second, respectively. The yttrium addition to SAM1651 enhances glass formation, as reported by Guo and Poon [2003]. The corrosion behavior of SAM1651 was compared with nickel-based Alloy 22 in electrochemical polarization measurements performed in several highly concentrated chloride solutions.

Lian, T; Day, S D; Farmer, J C

2006-04-10T23:59:59.000Z

325

Electronic Origin For The Phase Transition From Amorphous LixSi To Crystalline Li15Si4  

SciTech Connect

Silicon has been widely explored as an anode material for lithium ion battery. Upon lithiation, silicon transforms to amorphous LixSi (a-LixSi) via electrochemical driven solid state amorphization. With increasing lithium concentration, a-LixSi transforms to crystalline Li15Si4 (c-Li15Si4). The mechanism of this crystallization process is not known. In this paper, we report the fundamental characteristics of the phase transition of a-LixSi to c-Li15Si4 using in-situ scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS), and density function theory (DFT) calculation. We find that when the lithium concentration in a-LixSi reaches a critical value of x = 3.75, the a-Li3.75Si spontaneously and congruently transforms to c-Li15Si4 by a process that is solely controlled by the lithium concentration in the a-LixSi, involving neither large scale atomic migration nor phase separation. DFT calculations indicate that c-Li15Si4 formation is favored over other possible crystalline phases due to the similarity in electronic structure with a-Li3.75Si.

Gu, Meng; Wang, Zhiguo; Connell, Justin G.; Perea, Daniel E.; Lauhon, Lincoln J.; Gao, Fei; Wang, Chong M.

2013-06-24T23:59:59.000Z

326

Cryogenic ion implantation near amorphization threshold dose for halo/extension junction improvement in sub-30 nm device technologies  

SciTech Connect

We report on junction advantages of cryogenic ion implantation with medium current implanters. We propose a methodical approach on maximizing cryogenic effects on junction characteristics near the amorphization threshold doses that are typically used for halo implants for sub-30 nm technologies. BF{sub 2}{sup +} implant at a dose of 8 Multiplication-Sign 10{sup 13}cm{sup -2} does not amorphize silicon at room temperature. When implanted at -100 Degree-Sign C, it forms a 30 - 35 nm thick amorphous layer. The cryogenic BF{sub 2}{sup +} implant significantly reduces the depth of the boron distribution, both as-implanted and after anneals, which improves short channel rolloff characteristics. It also creates a shallower n{sup +}-p junction by steepening profiles of arsenic that is subsequently implanted in the surface region. We demonstrate effects of implant sequences, germanium preamorphization, indium and carbon co-implants for extension/halo process integration. When applied to sequences such as Ge+As+C+In+BF{sub 2}{sup +}, the cryogenic implants at -100 Degree-Sign C enable removal of Ge preamorphization, and form more active n{sup +}-p junctions and steeper B and In halo profiles than sequences at room temperature.

Park, Hugh; Todorov, Stan; Colombeau, Benjamin; Rodier, Dennis; Kouzminov, Dimitry; Zou Wei; Guo Baonian; Khasgiwale, Niranjan; Decker-Lucke, Kurt [Applied Materials, Varian Semiconductor Equipment, 35 Dory Road, Gloucester, Massachusetts 01930 (United States)

2012-11-06T23:59:59.000Z

327

Micromachined silicon electrostatic chuck  

DOE Patents (OSTI)

In the field of microelectronics, and in particular the fabrication of microelectronics during plasma etching processes, electrostatic chucks have been used to hold silicon wafers during the plasma etching process. Current electrostatic chucks that operate by the {open_quotes}Johnson-Rahbek Effect{close_quotes} consist of a metallic base plate that is typically coated with a thick layer of slightly conductive dielectric material. A silicon wafer of approximately the same size as the chuck is placed on top of the chuck and a potential difference of several hundred volts is applied between the silicon and the base plate of the electrostatic chuck. This causes an electrostatic attraction proportional to the square of the electric field in the gap between the silicon wafer and the chuck face. When the chuck is used in a plasma filled chamber the electric potential of the wafer tends to be fixed by the effective potential of the plasma. The purpose of the dielectric layer on the chuck is to prevent the silicon wafer from coming into direct electrical contact with the metallic part of the chuck and shorting out the potential difference. On the other hand, a small amount of conductivity appears to be desirable in the dielectric coating so that much of its free surface between points of contact with the silicon wafer is maintained near the potential of the metallic base plate; otherwise, a much larger potential difference would be needed to produce a sufficiently large electric field in the vacuum gap between the wafer and chuck. Typically, the face of the chuck has a pattern of grooves in which about 10 torr pressure of helium gas is maintained. This gas provides cooling (thermal contact) between the wafer and the chuck. A pressure of 10 torr is equivalent to about 0.2 psi.

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

1994-12-31T23:59:59.000Z

328

Electrochemical thinning of silicon  

DOE Patents (OSTI)

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.

Medernach, J.W.

1994-01-11T23:59:59.000Z

329

Synthesis of silane and silicon in a nonequilibrium plasma jet. Final report  

DOE Green Energy (OSTI)

The original objective of this program was to determine the feasibility of high volume, low-cost production of high purity silane or solar cell grade silicon using a nonequilibrium plasma jet. The emphasis was changed near the end of the program to determine the feasibility of preparing photovoltaic amorphous silicon films directly using this method. The nonequilibrium plasma jet is produced by partially dissociating hydrogen to hydrogen atoms in a 50 to 100 Torr glow discharge and expanding the H/H/sub 2/ mixture through a nozzle. A high flux density of hydrogen atoms is thus produced at concentrations of about 3 mol % with about 30% energy utilization efficiency. The jet is mixed with a second reactant and the reaction proceeds at a temperature of 400 to 600/sup 0/K to produce products. Yields of SiH/sub 4/, SiHCl/sub 3/, or SiH/sub 2/Cl/sub 2/ from SiCl/sub 4/ and SiHCl/sub 3/ were too low to be economically attractive. However, both amorphous and polycrystalline silicon films which strongly adhered to Pyrex, Vycor, aluminum, or carbon were prepared with either SiCl/sub 4/ or SiHCl/sub 3/ reactants. Preliminary doping experiments with PH/sub 3/ did not alter the electrical resistivity of these films. Strongly adhering films with SiH/sub 4/ reactant were more difficult to prepare; they were prepared by carefully cleaning the aluminum substrate, diluting the SiH/sub 4/ with about 90% argon, and forming the glow discharge between the mixing nozzle and the aluminum substrate. Doping such films with P by adding PH/sub 3/ reduced the electrical resistivity by two orders of magnitude. The nonequilibrium plasma jet should be further evaluated as a technique for producing high efficiency photovoltaic amorphous silicon films.

Calcote, H.F.

1978-10-01T23:59:59.000Z

330

Amorphous hafnium-indium-zinc oxide semiconductor thin film transistors  

Science Conference Proceedings (OSTI)

We reported on the performance and electrical properties of co-sputtering-processed amorphous hafnium-indium-zinc oxide (?-HfIZO) thin film transistors (TFTs). Co-sputtering-processed ?-HfIZO thin films have shown an amorphous phase in nature. ...

Sheng-Po Chang; San-Syong Shih

2012-01-01T23:59:59.000Z

331

Method For Silicon Surface Texturing Using Ion Implantation  

Science Conference Proceedings (OSTI)

As the semiconductor industry continues to show more interest in the photovoltaic market, cheaper and readily integrable methods of silicon solar cell production are desired. One of these methods - ion implantation - is well-developed and optimized in all commercial semiconductor fabrication facilities. Here we have developed a silicon surface texturing technique predicated upon the phenomenon of surface blistering of H-implanted silicon, using only ion implantation and thermal annealing. We find that following the H implant with a second, heavier implant markedly enhances the surface blistering, causing large trenches that act as a surface texturing of c-Si. We have found that this method reduces total broadband Si reflectance from 35% to below 5percent;. In addition, we have used Rutherford backscattering/channeling measurements investigate the effect of ion implantation on the crystallinity of the sample. The data suggests that implantation-induced lattice damage is recovered upon annealing, reproducing the original monocrystalline structure in the previously amorphized region, while at the same time retaining the textured surface.

Kadakia, Nirag; Naczas, Sebastian; Bakhru, Hassaram; Huang Mengbing [College of Nanoscale Science and Engineering, State University of New York at Albany, 255 Fuller Road, Albany NY 12203 (United States)

2011-06-01T23:59:59.000Z

332

CORROSION STUDY OF AMORPHOUS METAL RIBBONS  

SciTech Connect

Corrosion costs the Department of Defense billions of dollars every year, with an immense quantity of material in various structures undergoing corrosion. For example, in addition to fluid and seawater piping, ballast tanks, and propulsions systems, approximately 345 million square feet of structure aboard naval ships and crafts require costly corrosion control measures. The use of advanced corrosion-resistant materials to prevent the continuous degradation of this massive surface area would be extremely beneficial. The potential advantages of amorphous metals have been recognized for some time [Latanison 1985]. Iron-based corrosion-resistant, amorphous-metal coatings under development may prove important for maritime applications [Farmer et al. 2005]. Such materials could also be used to coat the entire outer surface of containers for the transportation and long-term storage of spent nuclear fuel, or to protect welds and heat affected zones, thereby preventing exposure to environments that might cause stress corrosion cracking [Farmer et al. 1991, 2000a, 2000b]. In the future, it may be possible to substitute such high-performance iron-based materials for more-expensive nickel-based alloys, thereby enabling cost savings in a wide variety of industrial applications. It should be noted that thermal-spray ceramic coatings have also been investigated for such applications [Haslam et al. 2005]. This report focuses on the corrosion resistance of iron-based melt-spun amorphous metal ribbons. Melt-Spun ribbon is made by rapid solidification--a stream of molten metal is dropped onto a spinning copper wheel, a process that enables the manufacture of amorphous metals which are unable to be manufactured by conventional cold or hot rolling techniques. The study of melt-spun ribbon allows quick evaluation of amorphous metals corrosion resistance. The melt-spun ribbons included in this study are DAR40, SAM7, and SAM8, SAM1X series, and SAM2X series. The SAM1X series ribbons have Ni additions in increments of 1, 3, 5, and 7 atom percent, to DAR40. For example, 1X7 means a composition of 7-atom% Ni added to 93-atom% of DAR40. Similarly, The SAM1X series ribbons have Mo additions in increments of 1, 3, 5, and 7 atom percent, to DAR40. For example, 2X3 means a composition of 3-atom% Mo added to 97-atom% of DAR40. SAM7 ribbon is a Fe-Cr-Mo-Y-C-B metal glass, commonly called Alloy1651. SAM8 is SAM7 with an additional 3-atom% W. The nominal compositions of DAR40 and SAM7 are listed in Table 1. SAM7 ribbon is extremely brittle and hard to manufactured by melt-spinning, only limited number of SAM7 ribbons were tested.

Lian, T; Day, S D; Farmer, J C

2006-07-31T23:59:59.000Z

333

Crystalline silicon processing  

DOE Green Energy (OSTI)

This presentation (consisting of vugraphs) first provides the background motivation for Sandia`s effort for the development of improved crystalline silicon solar cells. It then discusses specific results and progress, and concludes with a brief discussion of options for next year.

Basore, P.A.

1994-07-13T23:59:59.000Z

334

Excess Specific Heat in Evaporated Amorphous Silicon D. R. Queen,1,* X. Liu,2  

E-Print Network (OSTI)

] and molecular dynamics simulations [38] both associate an increase in the vibrational density of states in a. Revaz, B. L. Zink, and F. Hellman, Thermochim. Acta 432, 158 (2005). [23] X. Liu and H. V. Lo

Hellman, Frances

335

Optimization of transparent and reflecting electrodes for amorphous silicon solar cells  

DOE Green Energy (OSTI)

This report describes work to improve the performance of solar cells by improving the electrical and optical properties of their transparent conducting oxides (TCO) layers. Boron-doped zinc-oxide films were deposited by atmospheric pressure chemical vapor deposition in a laminar-flow reactor from diethyl zinc, tert-butanol, and diborane in the temperature range between 300[degrees]C and 420[degrees]C. When the deposition temperature was above 320[degrees]C, both doped and undoped films have highly oriented crystallites with their c-axes perpendicular to the substrate plane. Films deposited from 0.07% diethyl zinc and 2.4% tert-butanol have electron densities between 3.5 [times] 10[sup 20] cm[sup [minus]3] and 5.5 [times] 10[sup 20] cm[sup [minus]3], conductivities between 250 [Omega][sup [minus]1] and 2500 [Omega][sup [minus]1] and mobilities between 2.5 cm[sup 2]/V-s and 35.0 cm[sup 2]/V-s, depending on dopant concentration, film thickness, and deposition temperature. Optical measurements show that the maximum infrared reflectance of the doped films is close to 90%, compared to about 20% for undoped films. Film visible absorption and film conductivity were found to increase with film thickness. The ratio of conductivity to visible absorption coefficient for doped films was between 0.1 [Omega] and 1.1 [Omega][sup [minus]1]. The band gap of the film changes from 3.3 eV to 3.7 eV when the film is doped with 0.012% diborane.

Gordon, R.G. (Harvard Univ., Cambridge, MA (United States). Dept. of Chemistry)

1993-04-01T23:59:59.000Z

336

Energetics of hydrogen in amorphous silicon: An ab initio study Blair Tuttle*  

E-Print Network (OSTI)

poten- tial energy would determine the occupancy of various hydro- gen binding states. However, recent, after 70% of the hydro- gen evolved, the activation energy was 2.1 eV. In general, there may theoreti- cal studies. We provide estimates for the energies of hydro- gen trap levels ET , ES , and ED

Adams, James B

337

Process For Direct Integration Of A Thin-Film Silicon P-N Junction Diode With A Magnetic Tunnel Junction  

DOE Patents (OSTI)

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.

Toet, Daniel (Mountain View, CA); Sigmon, Thomas W. (Albuquerque, NM)

2005-08-23T23:59:59.000Z

338

Process for direct integration of a thin-film silicon p-n junction diode with a magnetic tunnel junction  

DOE Patents (OSTI)

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.

Toet, Daniel (Mountain View, CA); Sigmon, Thomas W. (Albuquerque, NM)

2003-01-01T23:59:59.000Z

339

Optical Design and Analysis of Textured a-Si Solar Cells: Preprint  

DOE Green Energy (OSTI)

The effect of texture on enhancement and losses in photocurrent in a-Si solar cells is explored using PVOPTICS software and measurements on a-Si device structures. The texture angle has a major impact on light trapping and internal reflection. Increasing the angle causes better internal trapping in the i-layer, but also higher SnO2/a-Si reflection losses, as well as SnO2 and metal absorption losses. Parasitic absorption in the textured SnO2 due to back reflected light is 1-2 mA/cm2 for typical designs. N-i-p cells have a fundamental advantage over p-i-n cells since the textured TCO is at the rear of the device leading to lower losses.

Hegedus, S.; Paulson, P. D.; Sopori, B.

2002-05-01T23:59:59.000Z

340

High efficiency thin film CdTe and a-Si based solar cells  

DOE Green Energy (OSTI)

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{sup {minus}5} torr) was beneficial for growing high-quality films from ITO targets.

Compaan, A. D.; Deng, X.; Bohn, R. G.

2000-01-04T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Formation of molecular hydrogen on amorphous silicate surfaces  

E-Print Network (OSTI)

Experimental results on the formation of molecular hydrogen on amorphous silicate surfaces are presented and analyzed using a rate equation model. The energy barriers for the relevant diffusion and desorption processes are obtained. They turn out to be significantly higher than those obtained for polycrystalline silicates, demonstrating the importance of grain morphology. Using these barriers we evaluate the efficiency of molecular hydrogen formation on amorphous silicate grains under interstellar conditions. It is found that unlike polycrystalline silicates, amorphous silicate grains are efficient catalysts of H_2 formation in diffuse interstellar clouds.

Ling Li; Giulio Manico; Emanuele Congiu; Joe Roser; Sol Swords; Hagai B. Perets; Adina Lederhendler; Ofer Biham; John Robert Brucato; Valerio Pirronello; Gianfranco Vidali

2007-09-16T23:59:59.000Z

342

Effect of hydrogen on ground state structures of small silicon clusters  

E-Print Network (OSTI)

We present results for ground state structures of small SinH (2?n ?10) clusters using the Car-Parrinello molecular dynamics. In particular, we focus on how the addition of a hydrogen atom affects the ground state geometry, total energy and the first excited electronic level gap of an Sin cluster. We discuss the nature of bonding of hydrogen in these clusters. We find that hydrogen bonds with two silicon atoms only in Si2H, Si3H and Si5H clusters, while in other clusters (i.e. Si4H, Si6H, Si7H, Si8H, Si9H and Si10H) hydrogen is bonded to only one silicon atom. Also in the case of a compact and closed silicon cluster hydrogen bonds to the cluster from outside. We find that the first excited electronic level gap of Sin and SinH fluctuates as a function of size and this may provide a first principles basis for the short-range potential fluctuations in hydrogenated amorphous silicon. Our results show that the addition of a single hydrogen can cause large changes in the electronic structure of a silicon cluster, though the geometry is not much affected. Our calculation of the lowest energy fragmentation products of SinH clusters shows that hydrogen is easily removed from SinH clusters. PACS numbers: 71.15.Pd, 73.22.-f, 61.46.+w2 I

D. Balamurugan; R. Prasad

2008-01-01T23:59:59.000Z

343

Silicon Cells | Open Energy Information  

Open Energy Info (EERE)

Cells Cells Jump to: navigation, search Name Silicon Cells Place United Kingdom Product Technology developer based upon a low cost method of processing silicon to produce a new generation of high energy density batteries. References Silicon Cells[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. Silicon Cells is a company located in United Kingdom . References ↑ "Silicon Cells" Retrieved from "http://en.openei.org/w/index.php?title=Silicon_Cells&oldid=351081" Categories: Clean Energy Organizations Companies Organizations Stubs What links here Related changes Special pages Printable version Permanent link Browse properties About us Disclaimers Energy blogs

344

Modified silicon carbide whiskers  

DOE Patents (OSTI)

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.

Tiegs, T.N.; Lindemer, T.B.

1991-05-21T23:59:59.000Z

345

Modified silicon carbide whiskers  

DOE Patents (OSTI)

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.

Tiegs, Terry N. (Lenoir City, TN); Lindemer, Terrence B. (Oak Ridge, TN)

1991-01-01T23:59:59.000Z

346

Bagdad Plant Raymond J. Polinski 585 Silicon Drive General Manager  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Bagdad Plant Raymond J. Polinski Bagdad Plant Raymond J. Polinski 585 Silicon Drive General Manager Leechburg, PA 15656 Grain-Oriented Electrical Steel e-mail: Raymond.Polinski@ATImetals.com E. Below are Allegheny Technologies Incorporated's comments on certain issues in which the DOE sought comment. 17. DOE seeks comment on nanotechnology composites and their potential for use in distribution transformers. Soft magnetic and amorphous particles with excellent magnetic properties can be and are currently produced, but the insulating matrix required to eliminate short-circuit paths dissipate power at the operating frequencies for power distribution transformers (50/60 Hz). Such transformer cores are currently only used for high-frequency applications where significant

347

Physical Properties of HWCVD Microcrystalline Silicon Thin Films: Preprint  

DOE Green Energy (OSTI)

This conference paper describes Microcrystalline silicon films were grown with different thicknesses and different hydrogen dilution ratios on glass and Si substrates. Some films were deposited with a seed layer, whereas others were deposited directly on the substrate. We used atomic force microscopy, scanning electron microscopy, and X-ray diffraction to study the morphology and crystalline structure of the samples. We did not find a significant influence of the different substrates on the morphology or crystalline structure. The presence of the seed layer enhanced the crystallization process, decreasing the amount of amorphous layer present in the films. The microstructure of most films was formed by grains, with a subgrain structure. Films grown with low values of dilution ratio had (220) texture and elongated grains, whereas films deposited with high values of dilution ratio were randomly oriented and had an irregular shape.

Moutinho, H. R.; Romero, M. J.; Jiang, C. S.; Xu, Y.; Nelson, B. P.; Jones, K. M.; Mahan, A. H.; Al-Jassim, M. M.

2002-05-01T23:59:59.000Z

348

Polymorphism of the glass former ethanol confined in mesoporous silicon  

E-Print Network (OSTI)

X-ray diffraction patterns of ethanol confined in parallel-aligned channels of approx. 10 nm diameter and 50 micrometer length in mesoporous silicon have been recorded as a function of filling fraction, temperature and for varying cooling and heating rates. A sorption isotherm, recorded in the liquid state, indicates a three monolayer thick, strongly adsorbed wall layer and a capillary condensed fraction of molecules in the pore center. Though the strongly adsorbed film remains in an amorphous state for the entire temperature range investigated, the capillary condensed molecules reproduce the polymorphism of bulk solid ethanol, that is the formation of either crystalline or glass-like states as a function of cooling rate. The critical rate necessary to achieve a vitrification in the mesopores is, however, at least two orders of magnitude smaller than in the bulk state. This finding can be traced both to pure geometrical constraints and quenched disorder effects, characteristic of confinement in mesoporous sil...

Henschel, Anke; Huber, Patrick; 10.1080/09500831003766999

2010-01-01T23:59:59.000Z

349

Properties of vacuum arc deposited amorphous hard carbon films  

Science Conference Proceedings (OSTI)

Amorphous hard carbon films formed by vacuum arc deposition are hydrogen-free, dense, and very hard. The properties of amorphous hard carbon films depend strongly on the energy of the incident ions. A technique which is called Plasma Immersion Ion Implantation can be applied to vacuum arc deposition of amorphous hard carbon films to influence the ion energy. The authors have studied the influence of the ion energy on the elastic modulus determined by an ultrasonic method, and have measured the optical gap for films with the highest sp{sup 3} content they have obtained so far with this deposition technique. The results show an elastic modulus close to that of diamond, and an optical gap of 2.1 eV which is much greater than for amorphous hard carbon films deposited by other techniques.

Anders, S.; Anders, A.; Raoux, S. [Lawrence Berkeley Lab., CA (United States)] [and others

1995-04-01T23:59:59.000Z

350

Structural and electronic studies of a-SiGe:H alloys  

DOE Green Energy (OSTI)

This report describes work to produce alloys of a-Si[sub 1-x]Ge[sub x]:H of improved photoelectronic quality by plasma-enhanced chemical vapor deposition (PECVD). The goal was to discover optimum preparation conditions for the end-component, a-Ge:H, to establish whether modification of the usual practice of starting from a-Si:H preparation conditions was advisable. Such modification, found to be necessary, gave films of a-Ge:H with efficiency-mobility-lifetime products ([eta][mu][tau]) 10[sup 2] to 10[sup 3] higher than were earlier available, in homogeneous environmentally stable material. Both a-Ge:H and a-Si[sub 1-x]Ge[sub x]:H of large x were studied in detail. Alloy material was shown to have [eta][mu][tau] 10[sup 2] larger than found earlier. However, just as the [eta][mu][tau] of a-Si:H decreases when Ge is added, so also the [eta][mu][tau] of these alloys with Si addition. By contrast, the ambipolar diffusion lengths, L[sub o] which are governed by the hole mobility, vary by only a factor of two over the whole alloy series. Using the experimental finding of a small valence band offset between a-Si:H and a-Ge:H compositional fluctuations on a 10-mm scale are suggested to explain the behavior of [eta][mu][tau] and L[sub o] The implications for eventual improvement of the alloys are profound, but require direct experimental tests of the postulated compositional fluctuations.

Paul, W. (Harvard Univ., Cambridge, MA (United States))

1993-04-01T23:59:59.000Z

351

Improved blue response and efficiency of A-Si:H solar cells deposited from disilane using a dual-chamber plasma system  

DOE Green Energy (OSTI)

Thin film amorphous silicon solar cells with glass/SnO/sub 2//p/i/n/Al structures and 6 to 7% AM1 conversion efficiencies were fabricated at rapid deposition rates in a newly constructed dual-chamber glow discharge deposition system. The 500 nm thick intrinsic layer was deposited at the rate of 1.7 nm/s using disilane (Si/sub 2/H/sub 6/)-helium mixtures. This deposition rate is an order of magnitude greater than conventional high efficiency amorphous silicon solar cell depositions. Residual boron doping effects at the p/i interface can severely degrade cell performance particularly when the intrinsic layer is deposited in one chamber of the dual-chamber system and the intrinsic layer is deposited in the other chamber that is free of boron contaminants. Parameters such as electrode spacing, Si/sub 2/H/sub 6/ partial pressure and flow rate were optimized to produce uniform deposition over large areas. At the substrate temperature T/sub s/ selected for solar cell intrinsic layer deposition, the spin density was measured to be a minimum at 5 x 10/sup 15//cm/sup 3/. For a given T/sub s/, an intrinsic layer deposited from Si/sub 2/H/sub 6/ absorbs fewer photons and can generate less current under solar simulation than a similar film produced from monosilane. Identical solar cells were deposited in either the single-chamber mode or the dual-chamber mode for comparison. Single-chamber mode cells perform poorly over the visible wavelengths and hence produce low short circuit currents. The dual-chamber mode cells show a significant improvement in blue response and a factor of two increase in short circuit current over the single-chamber mode cells. Under short circuit conditions, 15 mA/cm/sup 2/ was generated from rapidly deposited (1.7 nm/s) cells from disilane and 18 mA/cm/sup 2/ from low deposition rate (0.18 nm/s) monosilane cells. These values are comparable to or better than those reported for similar cells by other groups.

Rajeswaran, G.; Vanier, P.E.; Corderman, R.R.; Kampas, F.J.

1985-01-01T23:59:59.000Z

352

Spin--wave spectrum of an amorphous ferromagnet  

SciTech Connect

The spin-wave spectruin of an amorphous Heisenberg ferromagnet is calculated by a diagrammatic expansion making use of a transformation due to Taylor and Wu Phys. Rev., B2: 1752 (1970). The upper limit of the spectrum is found to occur at frequencies below that of the corresponding crystalline system, while the low-frequency part of the spectrum is enhanced. Internal van Hove singularities are absent in the spin-wave spectrum of the amorphous ferromagnet. (auth)

Gubernatis, J.E.; Taylor, P.L.

1973-01-01T23:59:59.000Z

353

Implementation Challenges for Sintered Silicon Carbide Fiber ...  

Science Conference Proceedings (OSTI)

The sintered silicon carbide fiber bonded ceramics have been fabricated by the hot pressing and sintering of silicon carbide fibers. However, in this system...

354

The Quest for Inexpensive Silicon Solar Cells  

To learn more about NREL's silicon solar cell research, visit the Silicon Materials and Devices Web site. Did you find what you needed? Yes No. Thank ...

355

Proof of damage-free selective removal of thin dielectric coatings on silicon wafers by irradiation with femtosecond laser pulses  

Science Conference Proceedings (OSTI)

The microstructural impact of selective femtosecond laser ablation of thin dielectric layers from monocrystalline silicon wafers was investigated. Various spots opened by 280 fs laser pulses at {lambda} = 1.03 {mu}m wavelength and 50 fs pulses at 800 nm, respectively, were analyzed in detail using Raman and transmission electron microscopy. The results show clearly that the thin dielectric films can be removed without any detectable modification of the Si crystal structure in the opened area. In contrast, in adjacent regions corresponding to laser fluence slightly below the breaking threshold, a thin layer of amorphous silicon with a maximum thickness of about 50 nm is found at the Si/SiO{sub 2} interface after laser irradiation. More than one pulse on the same position, however, causes structural modification of the silicon after thin film ablation in any case.

Rublack, Tino; Muchow, Markus [Zentrum fuer Innovationskompetenz SiLi-nano, Martin-Luther-Universitaet Halle-Wittenberg, 06120 Halle (Germany); Schade, Martin; Leipner, Hartmut S. [Interdisziplinaeres Zentrum fuer Materialwissenschaften, Martin-Luther-Universitaet Halle-Wittenberg, 06099 Halle (Germany); Seifert, Gerhard [Zentrum fuer Innovationskompetenz SiLi-nano, Martin-Luther-Universitaet Halle-Wittenberg, 06120 Halle (Germany); Fraunhofer-Center for Silicon Photovoltaics CSP, 06120 Halle (Germany)

2012-07-15T23:59:59.000Z

356

Nanostructured plasmonics silicon solar cells  

Science Conference Proceedings (OSTI)

We report a plasmonics silicon solar cell design, with the possibility of lower cost and higher efficiency. The proposed solar cell consists of a radial p-n junction silicon nanopillar arrays in combination with metallic nanoparticles resolved at the ... Keywords: Antireflection coating, Optical absorption, Power conversion efficiency, Solar cells

Pushpa Raj Pudasaini, Arturo A. Ayon

2013-10-01T23:59:59.000Z

357

Interactions of chlorine plasmas with silicon chloride-coated reactor walls during and after silicon etching  

SciTech Connect

The interplay between chlorine inductively coupled plasmas (ICP) and reactor walls coated with silicon etching products has been studied in situ by Auger electron spectroscopy and line-of-sight mass spectrometry using the spinning wall method. A bare silicon wafer mounted on a radio frequency powered electrode (-108 V dc self-bias) was etched in a 13.56 MHz, 400 W ICP. Etching products, along with some oxygen due to erosion of the discharge tube, deposit a Si-oxychloride layer on the plasma reactor walls, including the rotating substrate surface. Without Si-substrate bias, the layer that was previously deposited on the walls with Si-substrate bias reacts with Cl-atoms in the chlorine plasma, forming products that desorb, fragment in the plasma, stick on the spinning wall and sometimes react, and then desorb and are detected by the mass spectrometer. In addition to mass-to-charge (m/e) signals at 63, 98, 133, and 168, corresponding to SiCl{sub x} (x = 1 - 4), many Si-oxychloride fragments with m/e = 107, 177, 196, 212, 231, 247, 275, 291, 294, 307, 329, 345, 361, and 392 were also observed from what appear to be major products desorbing from the spinning wall. It is shown that the evolution of etching products is a complex 'recycling' process in which these species deposit and desorb from the walls many times, and repeatedly fragment in the plasma before being detected by the mass spectrometer. SiCl{sub 3} sticks on the walls and appears to desorb for at least milliseconds after exposure to the chlorine plasma. Notably absent are signals at m/e = 70 and 72, indicating little or no Langmuir-Hinshelwood recombination of Cl on this surface, in contrast to previous studies done in the absence of Si etching.

Khare, Rohit; Srivastava, Ashutosh; Donnelly, Vincent M. [Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204 (United States)

2012-09-15T23:59:59.000Z

358

Phase Diagram of Amorphous Solid Water: Low-Density, High-Density, and Very-High-Density Amorphous Ices  

E-Print Network (OSTI)

We describe the phase diagram of amorphous solid water by performing molecular dynamics simulations. Our simulations follow different paths in the phase diagram: isothermal compression/decompression, isochoric cooling/heating and isobaric cooling/heating. We are able to identify low-density amorphous (LDA), high-density amorphous (HDA), and very-high density amorphous (VHDA) ices. The density $\\rho$ of these glasses at different pressure $P$ and temperature $T$ agree well with experimental values. We also study the radial distribution functions of glassy water. We obtain VHDA by isobaric heating of HDA, as in experiment. We also find that ``other forms'' of glassy water can be obtained upon isobaric heating of LDA, as well as amorphous ices formed during the transformation of LDA to HDA. We argue that these other forms of amorphous ices, as well as VHDA, are not altogether new glasses but rather are the result of aging induced by heating. Samples of HDA and VHDA with different densities are recovered at normal $P$, showing that there is a continuum of glasses. Furthermore, the two ranges of densities of recovered HDA and recovered VHDA overlap at ambient $P$. Our simulations are consistent with the possibility of HDA$\\to$LDA and VHDA$\\to$LDA transformations, reproducing the experimental findings. We do not observe a VHDA$\\to$HDA transformation.

Nicolas Giovambattista; H. Eugene Stanley; Francesco Sciortino

2005-02-22T23:59:59.000Z

359

A molecular mechanics study of morphologic interaction between graphene and Si nanowires on a SiO2 substrate  

Science Conference Proceedings (OSTI)

We study the morphologic interaction between graphene and Si nanowires on a SiO2 substrate, using molecular mechanics simulations. Two cases are considered: (1) a graphene nanoribbon intercalated by a single Si nanowire on a SiO2 ...

Zhao Zhang; Teng Li

2011-01-01T23:59:59.000Z

360

Low temperature production of large-grain polycrystalline semiconductors  

SciTech Connect

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.

Naseem, Hameed A. (Fayetteville, AR); Albarghouti, Marwan (Loudonville, NY)

2007-04-10T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Micromachined silicon seismic transducers  

SciTech Connect

Batch-fabricated silicon seismic transducers could revolutionize the discipline of CTBT monitoring by providing inexpensive, easily depolyable sensor arrays. Although our goal is to fabricate seismic sensors that provide the same performance level as the current state-of-the-art ``macro`` systems, if necessary one could deploy a larger number of these small sensors at closer proximity to the location being monitored in order to compensate for lower performance. We have chosen a modified pendulum design and are manufacturing prototypes in two different silicon micromachining fabrication technologies. The first set of prototypes, fabricated in our advanced surface- micromachining technology, are currently being packaged for testing in servo circuits -- we anticipate that these devices, which have masses in the 1--10 {mu}g range, will resolve sub-mG signals. Concurrently, we are developing a novel ``mold`` micromachining technology that promises to make proof masses in the 1--10 mg range possible -- our calculations indicate that devices made in this new technology will resolve down to at least sub-{mu}G signals, and may even approach to 10{sup {minus}10} G/{radical}Hz acceleration levels found in the low-earth-noise model.

Barron, C.C.; Fleming, J.G.; Sniegowski, J.J.; Armour, D.L.; Fleming, R.P.

1995-08-01T23:59:59.000Z

362

Cordierite silicon nitride filters  

SciTech Connect

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.

Sawyer, J.; Buchan, B. (Acurex Environmental Corp., Mountain View, CA (United States)); Duiven, R.; Berger, M. (Aerotherm Corp., Mountain View, CA (United States)); Cleveland, J.; Ferri, J. (GTE Products Corp., Towanda, PA (United States))

1992-02-01T23:59:59.000Z

363

Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites  

SciTech Connect

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.

Corman, Gregory Scot (Ballston Lake, NY); Luthra, Krishan Lal (Schenectady, NY)

2002-01-01T23:59:59.000Z

364

Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites  

SciTech Connect

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.

Corman, Gregory Scot (Ballston Lake, NY); Luthra, Krishan Lal (Schenectady, NY)

1999-01-01T23:59:59.000Z

365

Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites  

SciTech Connect

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.

Corman, G.S.; Luthra, K.L.

1999-09-14T23:59:59.000Z

366

Measuring the Casimir force gradient from graphene on a SiO_2 substrate  

E-Print Network (OSTI)

The gradient of the Casimir force between a Si-SiO${}_2$-graphene substrate and an Au-coated sphere is measured by means of a dynamic atomic force microscope operated in the frequency shift technique. It is shown that the presence of graphene leads to up to 9% increase in the force gradient at the shortest separation considered. This is in qualitative agreement with the predictions of an additive theory using the Dirac model of graphene.

A. A. Banishev; H. Wen; J. Xu; R. K. Kawakami; G. L. Klimchitskaya; V. M. Mostepanenko; U. Mohideen

2013-01-28T23:59:59.000Z

367

CYANATE ION IN COMPACT AMORPHOUS WATER ICE  

SciTech Connect

The 4.62 {mu}m infrared (2164.5 cm{sup -1}) absorption band, observed in ice mantels toward many young stellar objects, has been mostly attributed to the {nu}{sub 3} (CN stretch) band of OCN{sup -} ions. We present in this work a spectroscopic study of OCN{sup -} ions embedded in compact amorphous ice in a range of concentrations and temperatures relevant to astronomical observations together with quantum mechanical calculations of the {nu}{sub 3} band of OCN{sup -} in various H{sub 2}O environments. The ice samples containing the ions are prepared through hyperquenching of liquid droplets of K{sup +}OCN{sup -} solutions on a substrate at 14 K. The {nu}{sub 3} OCN{sup -} band appears as a broad feature peaking at 4.64 {mu}m with a secondary maximum at 4.54 {mu}m and is much weaker than the corresponding peak in the liquid solution or in the solid salt. A similar weakening is observed for other OCN{sup -} absorption peaks at 7.66 {mu}m (2{nu}{sub 2}) and 8.20 {mu}m ({nu}{sub 1}). The theoretical calculations for the {nu}{sub 3} vibration lead to a range of frequencies spanning the experimentally observed width. This frequency spread could help explain the pronounced drop in the band intensity in the ice. The OCN{sup -} {nu}{sub 3} band in the present compact ices is also broader and much weaker than that reported in the literature for OCN{sup -} ions obtained by variously processing porous ice samples containing suitable neutral precursors. The results of this study indicate that the astronomical detection of OCN{sup -} in ice mantels could be significantly impaired if the ion is embedded in a compact water network.

Mate, Belen; Herrero, Victor J.; Rodriguez-Lazcano, Yamilet; Moreno, Miguel A.; Escribano, Rafael [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, E-28006 Madrid (Spain); Fernandez-Torre, Delia [Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, E-28050 Madrid (Spain); Gomez, Pedro C. [Departamento de Quimica Fisica I, Universidad Complutense, Unidad Asociada UCM-CSIC, E-28040 Madrid (Spain)

2012-11-10T23:59:59.000Z

368

Silicon nitride ceramic comprising samaria and ytterbia  

Science Conference Proceedings (OSTI)

This invention relates to a sintered silicon nitride ceramic comprising samaria and ytterbia for enhanced toughness.

Yeckley, Russell L. (Oakham, MA)

1996-01-01T23:59:59.000Z

369

Preparation and properties of high-deposition-rate a-Si:H films and solar cells using disilane: Annual subcontract report, 1 May 1987--30 April 1988  

DOE Green Energy (OSTI)

This report contains results of the first year of research on producing p-i-n amorphous silicon solar cells with the intrinsic layer deposited from higher order silanes at deposition rates of 1 nm/s or more. The research was divided into three major areas: diagnostic studies of monosilane and disilane RF discharges using optical emission spectroscopy and mass spectrometry to assist in optimizing discharge conditions and gas-phase processes; parametric studies of material properties of 1-layers prepared form disilane as a function of deposition rate and other process parameters; and parametric studies of p-i-n devices with the i-layer prepared from disilane at various deposition rates. The focus during the first year was to fabricate a p-i-n solar cell with 9/percent/ AM1.5 efficiency over an area greater than 0.08 cm/sup 2/ with the i-layer deposited at 1 nm/s or more. Material properties such as the dark and AM1.5 light conductivities, optical band gap, and conductivity activation energy showed a weak dependence on deposition rate. The performance characteristics of unoptimized p-i-n solar cells with i-layers prepared from disilane were independent of the deposition rate of the i-layer. A p-i-n device was prepared at a rate close to 1 nm/s with an AM1.5 efficiency of 9/percent/. 20 refs, 26 figs, 2 tabs.

Bhat, P.K.; Chatham, H.; Madan, A.

1988-06-01T23:59:59.000Z

370

Preparation and properties of high deposition a-Si:H films and solar cells using disilane: Final subcontract report, 1 May 1988--30 April 1989  

DOE Green Energy (OSTI)

The focus of research during the second phase of SERI Contract No. ZB-7-06002-1 was the fabrication of high efficiency amorphous silicon p-i-n solar cells using intrinsic layers deposited at high deposition rate (/minus/2 nm/s) from disilane discharges. In order to achieve this goal, we utilized higher discharge excitation frequencies (10-110 MRz) to improve the intrinsic layer properties. In this report, we discuss the influence of the driving frequency at fixed fr power density on silane and disilane discharges, the properties of materials deposited from these discharges, and the performance of p-i-n devices fabricated using intrinsic layers deposited at a rate of /minus/2 nm/s from disilane 110 MRz discharges. The use of higher excitation frequency in disilane discharges increases the deposition rate and results in films with improved properties compared with those deposited at similar deposition rate by increasing the rf power. As a result of these improvements, we have fabricated a p-i-n device at a deposition rate of 2nm/s with an AM1.5 efficiency of 9/7% over an area of 1 cm/sup 2/. This result exceeds the goals of this contract. 24 refs., 16 figs., 2 tabs.

Chatham, H.; Bhat, P.K.

1989-09-01T23:59:59.000Z

371

Structure of Silicon-Based Thin Film Solar Cell Materials: Annual Technical Progress Report, 1 April 2002--31 August 2003  

DOE Green Energy (OSTI)

The purpose of this research is to achieve a better understanding to improve materials used as the intrinsic layers of amorphous and microcrystalline silicon-based solar cells. Fundamental structural properties will be investigated on atomic and nano-scales. A powerful combination of techniques will be used: analytical high-resolution transmission electron microscopy (HRTEM), including special associated spectroscopic methods, small-angle scattering techniques (SAXS, ASAXS, SANS), and conventional wide-angle X-ray diffraction (XRD).

Williamson, D. L.

2004-01-01T23:59:59.000Z

372

Process for forming retrograde profiles in silicon  

SciTech Connect

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.

Weiner, Kurt H. (San Jose, CA); Sigmon, Thomas W. (Phoenix, AZ)

1996-01-01T23:59:59.000Z

373

Comprehensive research on the stability and electronic properties of a-Si:H and a-SiGe:H alloys and devices. Final subcontract report, 10 March 1991--30 August 1994  

DOE Green Energy (OSTI)

This report describes work on the growth of a-Si:H and a-(Si,Ge):H materials and devices using well-controlled growth techniques. The a-Si:H materials were grown at higher temperatures (300{degrees}-375{degrees}C) using electron-cyclotron-resonance (ECR) plasma techniques with a remote H beam. These films have excellent electronic quality and show significant improvements in stability compared with glow-discharge-produced a-Si:H materials. Several problems were encountered during the fabrication of devices in these materials, and we were able to overcome them by a systematic work on buffer layers in these cells. We also studied alternative designs for improving the stability of a-Si:H cells and produced graded-gap a-Si:H cells using glow-discharge that are more stable than comparable standard, ungraded glow discharge devices. Finally, systematic work was done to produce good-quality a-(Si,Ge):H films, using triode radio frequency (RF) glow-discharge with ion bombardment during growth. Diagnostic devices were made using these films, and the properties of the material, such as Urbach energies and hole mobility-lifetime products, were measured in these devices. We found a systematic increase in the Urbach energies, and a corresponding decrease in the hole and electron {mu}{tau} products, as the Ge content of the alloys increases.

Dalal, V. [Iowa State Univ. of Science and Technology, Ames, IA (United States)

1995-04-01T23:59:59.000Z

374

Synthesis and Analysis of Alpha Silicon Carbide Components for Encapsulation of Fuel Rods and Pellets  

Science Conference Proceedings (OSTI)

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.

Kevin M. McHugh; John E. Garnier; George W. Griffith

2011-09-01T23:59:59.000Z

375

Electro-thermal behaviour of a SiC JFET stressed by lightning-induced overvoltages  

E-Print Network (OSTI)

: dominique.bergogne@insa-lyon.fr URL: http://www.ampere-lab.fr Keywords >, Silicon Carbide=11 and R3=66. K1 is a high voltage IGBT driven through a fiber-optic link, L1 is an air-coil inductor

Paris-Sud XI, Université de

376

Model for hydrogen isotope backscattering, trapping and depth profiles in C and a-Si  

DOE Green Energy (OSTI)

A model of low energy hydrogen trapping and backscattering in carbon and a-silicon is described. Depth profiles are calculated and numerical results presented for various incident angular and energy distributions. The calculations yield a relation between depth profiles and the incident ion energy distribution. The use of this model for tokamak plasma diagnosis is discussed.

Cohen, S.A.; McCracken, G.M.

1979-03-01T23:59:59.000Z

377

Deposited Silicon Photonics: Optical Interconnect Devices In Polycrystalline Silicon .  

E-Print Network (OSTI)

??Silicon photonics has tremendous potential to provide high-bandwidth and low-power data communication for applications such as computing and telecommunication, over length scales ranging from 100 (more)

Preston, Kyle

2011-01-01T23:59:59.000Z

378

Distribution of Local Open-Circuit Voltage on Amorphous and Nanocrystalline Mixed-Phase Si:H and SiGe:H Solar Cells: Preprint  

DOE Green Energy (OSTI)

Local open-circuit voltage (Voc) distributions on amorphous and nanocrystalline mixed-phase silicon solar cells were measured using a scanning Kelvin probe microscope (SKPM) on the p layer of an n-i-p structure without the top ITO contact. During the measurement, the sample was illuminated with a laser beam that was used for the atomic force microscopy (AFM). Therefore, the surface potential measured by SKPM is the sum of the local Voc and the difference in workfunction between the p layer and the AFM tip. Comparing the SKPM and AFM images, we find that nanocrystallites aggregate in the amorphous matrix with an aggregation size of {approx}0.5 ..mu..m in diameter, where many nanometer-size grains are clustered. The Voc distribution shows valleys in the nanocrystalline aggregation area. The transition from low to high Voc regions is a gradual change within a distance of about 1 ..mu..m. The minimum Voc value in the nanocrystalline clusters in the mixed-phase region is larger than the Voc of a nc-Si:H single-phase solar cell. These results could be due to lateral photo-charge redistribution between the two phases. We have also carried out local Voc measurements on mixed-phase SiGe:H alloy solar cells. The magnitudes of Voc in the amorphous and nanocrystalline regions are consistent with the J-V measurements.

Jiang, C.-S.; Moutinho, H. R.; Al-Jassim, M. M.; Kazmerski, L. L.; Yan, B.; Owens, J. M.; Yang, J.; Guha, S.

2006-05-01T23:59:59.000Z

379

Stress Management: Revealing Defects in Thin Silicon Films  

NLE Websites -- All DOE Office Websites (Extended Search)

caused by the manufacturing process for strained-silicon films. Strained silicon is a new, rapidly developing material for building enhanced-performance silicon-based...

380

Concentrator silicon cell research  

Science Conference Proceedings (OSTI)

This project continued the developments of high-efficiency silicon concentrator solar cells with the goal of achieving a cell efficiency in the 26 to 27 percent range at a concentration level of 150 suns of greater. The target efficiency was achieved with the new PERL (passivated emitter, rear locally diffused) cell structure, but only at low concentration levels around 20 suns. The PERL structure combines oxide passivation of both top and rear surfaces of the cells with small area contact to heavily doped regions on the top and rear surfaces. Efficiency in the 22 to 23 percent range was also demonstrated for large-area concentrator cells fabricated with the buried contact solar cell processing sequence, either when combined with prismatic covers or with other innovative approaches to reduce top contact shadowing. 19 refs.

Green, M.A.; Wenham, S.R.; Zhang, F.; Zhao, J.; Wang, A. [New South Wales Univ., Kensington (Australia). Solar Photovoltaic Lab.

1992-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Silicone plesiotherapy molds  

SciTech Connect

Plesiotherapy, the treatment of superficial lesions by radioactive molds has largely been replaced by teletherapy techniques involving high energy photon and electron beams. There are, however, situations for which a short distance type treatment, in one form or another, is superior to any other presently available. Traditionally, molds have taken the form of rigid devices incorporating clamps to attach them to the patient. This ensures a reproducible geometry about a localized region since the molds are applied on a daily basis. To make such devices requires considerable skill and patience. This article describes an alternative method that eliminates the use of cumbersome devices in many situations. Silicone molds made from a plaster cast model have been found suitable for the treatment of surface lesions and especially for lesions in the oral and nasal cavities. With the use of radioactive gold seeds the molds may be left in place for a few days without fear of them moving.

Karolis, C.; Reay-Young, P.S.; Walsh, W.; Velautham, G.

1983-04-01T23:59:59.000Z

382

Molecular Hydrogen Formation on Amorphous Silicates Under Interstellar Conditions  

E-Print Network (OSTI)

Experimental results on the formation of molecular hydrogen on amorphous silicate surfaces are presented for the first time and analyzed using a rate equation model. The energy barriers for the relevant diffusion and desorption processes are obtained. They turn out to be significantly higher than those obtained earlier for polycrystalline silicates, demonstrating the importance of grain morphology. Using these barriers we evaluate the efficiency of molecular hydrogen formation on amorphous silicate grains under interstellar conditions. It is found that unlike polycrystalline silicates, amorphous silicate grains are efficient catalysts of H$_{2}$ formation within a temperature range which is relevant to diffuse interstellar clouds. The results also indicate that the hydrogen molecules are thermalized with the surface and desorb with low kinetic energy. Thus, they are unlikely to occupy highly excited states.

Hagai B. Perets; Adina Lederhendler; Ofer Biham; Gianfranco Vidali; Ling Li; Sol Swords; Emanuele Congiu; Joe Roser; Giulio Manico; John Robert Brucato; Valerio Pirronello

2007-03-11T23:59:59.000Z

383

Plasma analysis and diagnostics for high efficiency amorphous solar cell production. Final report  

DOE Green Energy (OSTI)

This is a project that sought to improve the amorphous silicon-germanium (SiGe) thin film deposition process in the production of solar cells. To accomplish this, the electron cyclotron resonance (ECR) plasma discharge, employed for the thin film deposition, was modified. Changes in the parameters of the plasma were monitored with diagnostic techniques, similar to those used in fusion plasma studies. That was the primary contribution from ORNL. Only one phase was contained in the statement of work, with the following tasks: (1) Develop a detailed program for plasma characterization. (2) Carry-out plasma modeling and analysis to support deposition systems design. (3) Operate experimental deposition systems for the purpose of plasma characterization. (4) Analyze data. (5) Modify deposition as directed by measurements. (6) This final report, which was deemed to be the only deliverable of this small project. And while the modified ECR discharge did not show measurable improvement of the conditions relevant to the deposition process, much was learned about the plasma parameters in the process. Some ideas on alternative designs are being discuss and funding options for testing such designed are being sought.

Klepper, C.C.

1994-12-21T23:59:59.000Z

384

Chemical vapor deposition of amorphous semiconductor films. Semiannual report, 1 May 1983-31 October 1984  

DOE Green Energy (OSTI)

This report presents an analysis of intrinsic and phosphorus-doped n-type amorphous silicon films deposited by LPCVD from disilane in a laminar flow tubular reactor. These films were analyzed using SIMs, ESR measurements, optical absorption, and conductivity in light and dark. CVD deposited i layers were used to make platinum Schottky barrier devices and hybrid cells utilizing glow discharge deposited layers in both the ITO/nip/Mo and ITO/pin/Mo configurations. The highest efficiency of hybrid cells with the ITO/ni(CVD)/p(GD)/Mo structure was approximately 1.5%. The highest efficiencies were obtained with thin i layers. The highest efficiency for the ITO/p(GD)/in(CVD)/Mo configuration was 4.0%. A chemical model was developed describing the gas phase reactions and film growth; the model quantitatively describes the effluent composition when the measured growth rate is input. Kinetic rate expressions and constants for growth from higher silanes are being determined for a wide range of reaction conditions.

Not Available

1984-03-01T23:59:59.000Z

385

Development of high, stable-efficiency triple-junction a-Si alloy solar cells. Final technical report  

DOE Green Energy (OSTI)

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.

Deng, X.; Jones, S.J.; Liu, T.; Izu, M. [Energy Conversion Devices, Inc., Troy, MI (United States)

1998-04-01T23:59:59.000Z

386

Nano fabrication of silicon fins.  

E-Print Network (OSTI)

??We describe the formation of silicon micro- and nano-fins, with (111)-plane sidewall facets, for selective sidewall epitaxy of III-Nitride semiconductors. The fins were produced by (more)

Liu, Lianci

2012-01-01T23:59:59.000Z

387

Amorphous Metallic Glass as New High Power and Energy Density Anodes For Lithium Ion Rechargeable Batteries  

E-Print Network (OSTI)

We have investigated the use of aluminum based amorphous metallic glass as the anode in lithium ion rechargeable batteries. Amorphous metallic glasses have no long-range ordered microstructure; the atoms are less closely ...

Meng, Shirley Y.

388

The NREL Outdoor Accelerated-Weathering Tracking System Photovoltaic Module Exposure Results  

DOE Green Energy (OSTI)

Status results are presented for the Outdoor Accelerated-Weathering Tracking System (OATS) first study on photovoltaic (PV) modules. Studies began in November 1997 on pairs of commercially available crystalline silicon and amorphous silicon (a-Si) PV modules kept at constant resistive load.

Basso, T. S.

2000-01-01T23:59:59.000Z

389

Direct Production of Silicones From Sand  

Science Conference Proceedings (OSTI)

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.

Larry N. Lewis; F.J. Schattenmann: J.P. Lemmon

2001-09-30T23:59:59.000Z

390

On the photoinduced effect in undoped a-Si:H films  

SciTech Connect

The temperature dependences of the dark conductivity and photoconductivity of annealed and preliminarily illuminated undoped a-Si:H films are studied in different modes of temperature variation. Also, the variation kinetics of the photoconductivity and dark conductivity of the films during and after their exposure to light at different temperatures are analyzed. It is shown that the anomalous nature of the dependences obtained may be due to the formation of two kinds of photoinduced defects that have different energies of formation and thermal annealing and energy levels situated in different parts of the band gap of the films under study.

Kurova, I. A.; Ormont, N. N., E-mail: ormont@phys.msu.ru [Moscow State University, Faculty of Physics (Russian Federation)

2013-06-15T23:59:59.000Z

391

Structure-driven optimizations for amorphous data-parallel programs  

Science Conference Proceedings (OSTI)

Irregular algorithms are organized around pointer-based data structures such as graphs and trees, and they are ubiquitous in applications. Recent work by the Galois project has provided a systematic approach for parallelizing irregular applications based ... Keywords: amorphous data-parallelism, cautious operator implementations, irregular programs, iteration coalescing, one-shot optimization, optimistic parallelization, synchronization overheads

Mario Mndez-Lojo; Donald Nguyen; Dimitrios Prountzos; Xin Sui; M. Amber Hassaan; Milind Kulkarni; Martin Burtscher; Keshav Pingali

2010-01-01T23:59:59.000Z

392

Method of depositing wide bandgap amorphous semiconductor materials  

DOE Patents (OSTI)

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.

Ellis, Jr., Frank B. (Princeton Junction, NJ); Delahoy, Alan E. (Rocky Hill, NJ)

1987-09-29T23:59:59.000Z

393

BY SILICON CRYSTALS  

NLE Websites -- All DOE Office Websites (Extended Search)

c October 29, 1942 a 1 1 _MIGH aECTgFXCATIOH - BY SILICON CRYSTALS . . c .. I n. The excellent pesformmce of Brftieh "red dot" c r y s t a l s f e explained R R due t o the kgife edge contact i n a t A polfehod ~ X ' f l i C B o H i g h frequency m c t l f f c n t f o n 8ependre c r i t i c a l l y on the ape%e;y of the rectifytnc boundary layer o f the crystal, C, For hl#$ comvere~on e f f i c i e n c y , the product c d t h i ~ capacity m a o f ' t h e @forward" (bulk) re-. sistance Rb o f the crystnl must b@ sm%P, depende primarily on the breadth of tha b f f e edge i t s lbngth. The contact am &harefore ~ E L V Q a rather large area wMQh prevents burn-out, thh3 t h e breadth of &h@ knife edge should be bdt8~1 than E~$O$B% % f I - ' amo For a knife edge, this produet very 14ttle upom For a wavsIL~n+3tih of PO emo the eowp,o%a%8sne 4

394

Amorphous metal formulations and structured coatings for corrosion and wear resistance  

DOE Patents (OSTI)

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.

Farmer, Joseph C. (Tracy, CA)

2011-12-13T23:59:59.000Z

395

Laser wafering for silicon solar.  

Science Conference Proceedings (OSTI)

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 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.

Friedmann, Thomas Aquinas; Sweatt, William C.; Jared, Bradley Howell

2011-03-01T23:59:59.000Z

396

Enabling Thin Silicon Solar Cell Technology  

NLE Websites -- All DOE Office Websites (Extended Search)

Enabling Thin Silicon Solar Cell 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; however, silicon is brittle, and thinner silicon, coupled with other recent trends in SPV technologies (thinner glass, lighter or no metal frames, increased use of certain polymers for encapsulation of the silicon cells), is more susceptible to stress and cracking. When the thin

397

Photovoltaic Silicon Cell Basics | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Silicon Cell Basics Silicon Cell Basics Photovoltaic Silicon Cell Basics August 20, 2013 - 2:19pm Addthis Silicon-used to make some the earliest photovoltaic (PV) devices-is still the most popular material for solar cells. Silicon is also the second-most abundant element in the Earth's crust (after oxygen). However, to be useful as a semiconductor material in solar cells, silicon must be refined to a purity of 99.9999%. In single-crystal silicon, the molecular structure-which is the arrangement of atoms in the material-is uniform because the entire structure is grown from the same crystal. This uniformity is ideal for transferring electrons efficiently through the material. To make an effective PV cell, however, silicon has to be "doped" with other elements to make n-type and p-type layers.

398

Hybrid Silicon Photonic Integrated Circuit Technology  

E-Print Network (OSTI)

modulators for sili- con photonics, in Proc. IEEE Photon.J.E. Bowers, Hybrid silicon photonics for optical Intercon-The evolution of silicon photonics as an enabling technology

2013-01-01T23:59:59.000Z

399

Design of a silicon waver breaker  

E-Print Network (OSTI)

Usually multiple MEMS or IC devices are fabricated on a single silicon wafer. Manually separating the components from each other involves scribing and fracturing the silicon. This thesis presents a design for a tool to aid ...

Mukaddam, Kabir James, 1983-

2005-01-01T23:59:59.000Z

400

Types of Silicon Used in Photovoltaics  

Energy.gov (U.S. Department of Energy (DOE))

Siliconused to make some the earliest photovoltaic (PV) devicesis still the most popular material for solar cells. Silicon is also the second-most abundant element in the Earth's crust (after...

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Nucleation and solidification of silicon for photovoltaics  

E-Print Network (OSTI)

The majority of solar cells produced today are made with crystalline silicon wafers, which are typically manufactured by growing a large piece of silicon and then sawing it into ~200 pm wafers, a process which converts ...

Appapillai, Anjuli T. (Anjuli Tara)

2010-01-01T23:59:59.000Z

402

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...

403

System and method for liquid silicon containment  

SciTech Connect

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.

Cliber, James A; Clark, Roger F; Stoddard, Nathan G; Von Dollen, Paul

2013-05-28T23:59:59.000Z

404

Silicon crystal growing by oscillating crucible technique  

DOE Patents (OSTI)

A process for growing silicon crystals from a molten melt comprising oscillating the container during crystal growth is disclosed.

Schwuttke, G.H.; Kim, K.M.; Smetana, P.

1983-08-03T23:59:59.000Z

405

Demonstration of a silicon raman laser  

E-Print Network (OSTI)

The need for low-cost photonic devices has stimulated significant amount of research in silicon photonics. One avenue of this research is building active devices based on nonlinear properties of silicon. Raman effect in silicon is an attractive way of realizing these devices. In the last few years, spontaneous and stimulated Raman scattering have been demonstrated in Silicon-on-insulator (SOI) waveguides, showing the possibility of active functionalities based

Bahram Jalali; Ozdal Boyraz; Dimitri Dimitropoulos; Varun Raghunathan

2004-01-01T23:59:59.000Z

406

Solar Cell Silicon - Programmaster.org  

Science Conference Proceedings (OSTI)

Jul 31, 2012 ... About this Symposium. Meeting, 2013 TMS Annual Meeting & Exhibition. Symposium, Solar Cell Silicon. Sponsorship, TMS Extraction and...

407

Copper doped polycrystalline silicon solar cell  

DOE Patents (OSTI)

Photovoltaic cells having improved performance are fabricated from polycrystalline silicon containing copper segregated at the grain boundaries.

Lovelace, Alan M. Administrator of the National Aeronautics and Space (La Canada, CA); Koliwad, Krishna M. (La Canada, CA); Daud, Taher (La Crescenta, CA)

1981-01-01T23:59:59.000Z

408

Buckeye Silicon | Open Energy Information  

Open Energy Info (EERE)

Silicon Silicon Jump to: navigation, search Name Buckeye Silicon Address 2600 Dorr Street - Suite 1070 Place Toledo, Ohio Zip 43606 Sector Renewable Energy, Services, Solar Product Consulting; Manufacturing;Raw materials/extraction;Refining;Research and development Website http://www.sphereenergy.net Coordinates 41.6529122°, -83.6066466° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":41.6529122,"lon":-83.6066466,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}

409

Silicon Photonics: The Inside Story  

E-Print Network (OSTI)

The electronic chip industry embodies the height of technological sophistication and economics of scale. Fabricating inexpensive photonic components by leveraging this mighty manufacturing infrastructure has fueled intense interest in silicon photonics. If it can be done economically and in an energy efficient manner, empowering silicon with optical functionality will bring optical communications to the realm of computers where limitations of metallic interconnects are threatening the industry's future. The field is making stunning progress and stands to have a bright future, as long as the community recognizes the real challenges, and maintains an open mind with respect to its applications. This talk will review recent 'game changing' developments and discuss promising applications beyond data communication. It will conclude with recent observation of extreme-value statistical behavior in silicon photonics, a powerful example of how scientific discoveries can unexpectedly emerge in the course of technology d...

Jalali, Bahram

2008-01-01T23:59:59.000Z

410

Prealloyed catalyst for growing silicon carbide whiskers  

DOE Patents (OSTI)

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.

Shalek, Peter D. (Los Alamos, NM); Katz, Joel D. (Niagara Falls, NY); Hurley, George F. (Los Alamos, NM)

1988-01-01T23:59:59.000Z

411

Process of preparing tritiated porous silicon  

DOE Patents (OSTI)

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.

Tam, Shiu-Wing (Downers Grove, IL)

1997-01-01T23:59:59.000Z

412

Laser wafering for silicon solar.  

SciTech Connect

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.

Friedmann, Thomas Aquinas; Sweatt, William C.; Jared, Bradley Howell

2011-03-01T23:59:59.000Z

413

Erbium diffusion in silicon dioxide  

SciTech Connect

Erbium diffusion in silicon dioxide layers prepared by magnetron sputtering, chemical vapor deposition, and thermal growth has been investigated by secondary ion mass spectrometry, and diffusion coefficients have been extracted from simulations based on Fick's second law of diffusion. Erbium diffusion in magnetron sputtered silicon dioxide from buried erbium distributions has in particular been studied, and in this case a simple Arrhenius law can describe the diffusivity with an activation energy of 5.3{+-}0.1 eV. Within a factor of two, the erbium diffusion coefficients at a given temperature are identical for all investigated matrices.

Lu Yingwei; Julsgaard, B.; Petersen, M. Christian [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Jensen, R. V. Skougaard [Department of Physics and Nanotechnology, Aalborg University, DK-9220 Aalborg O (Denmark); Pedersen, T. Garm; Pedersen, K. [Department of Physics and Nanotechnology, Aalborg University, DK-9220 Aalborg O (Denmark); Interdisciplinary Nanoscience Center-iNANO, DK-8000 Aarhus C (Denmark); Larsen, A. Nylandsted [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Interdisciplinary Nanoscience Center-iNANO, DK-8000 Aarhus C (Denmark)

2010-10-04T23:59:59.000Z

414

Serial Powering of Silicon Sensors  

E-Print Network (OSTI)

Serial powering is a technique to provide power to a number of serially chained detector modules. It is an alternative option to independent powering that is particularly attractive when the number of modules is high, as in largescale silicon tracking detectors for particle physics. It uses a single power cable and a constant current source. On each module power is derived using local shunt regulators. Design aspects of local shunt regulators and system aspects of serial powering will be discussed. Test results and measurements obtained with a silicon strip supermodule will be presented. Specifications of radiation-hard custom serial powering circuitry will be discussed.

Villani, E G; Tyndel, M; Apsimon, R

2007-01-01T23:59:59.000Z

415

Fabrication of amorphous metal matrix composites by severe plastic deformation  

E-Print Network (OSTI)

Bulk metallic glasses (BMGs) have displayed impressive mechanical properties, but the use and dimensions of material have been limited due to critical cooling rate requirements and low ductility. The application of severe plastic deformation by equal channel angular extrusion (ECAE) for consolidation of bulk amorphous metals (BAM) and amorphous metal matrix composites (AMMC) is investigated in this dissertation. The objectives of this research are a) to better understand processing parameters which promote bonding between particles and b) to determine by what mechanisms the plasticity is enhanced in bulk amorphous metal matrix composites consolidated by ECAE. To accomplish the objectives BAM and AMMCs were produced via ECAE consolidation of Vitreloy 106a (Zr58.5Nb2.8Cu15.6Ni12.8Al10.3-wt%), ARLloy #1 (Hf71.3Cu16.2Ni7.6Ti2.2Al2.6 -wt%), and both of these amorphous alloys blended with crystalline phases of W, Cu and Ni. Novel instrumented extrusions and a host of postprocessing material characterizations were used to evaluate processing conditions and material properties. The results show that ECAE consolidation at temperatures within the supercooled liquid region gives near fully dense (>99%) and well bonded millimeter scale BAM and AMMCs. The mechanical properties of the ECAE processed BMG are comparable to cast material: Ï?f = 1640 MPa, ?µf = 2.3%, E = 80 GPa for consolidated Vitreloy 106a as compared to Ï?f = 1800 MPa, ?µf = 2.5%, E = 85 GPa for cast Vitreloy 106, and Ï?f = 1660 MPa, ?µf = 2.0%, E = 97 GPa for ARLloy #1 as compared to Ï?f = 2150 MPa, ?µf oxides and crystalline phase morphology and chemistry. It is demonstrated that the addition of a dispersed crystalline phase to an amorphous matrix by ECAE powder consolidation increases the plasticity of the amorphous matrix by providing locations for generation and/or arrest of adiabatic shear bands. The ability of ECAE to consolidated BAM and AMMCs with improved plasticity opens the possibility of overcoming the size and plasticity limitations of the monolithic bulk metallic glasses.

Mathaudhu, Suveen Nigel

2006-08-01T23:59:59.000Z

416

Growth of silicon sheets for photovoltaic applications  

DOE Green Energy (OSTI)

The status of silicon sheet development for photovoltaic applications is critically reviewed. Silicon sheet growth processes are classified according to their linear growth rates. The fast growth processes, which include edge-defined film-fed growth, silicon on ceramic, dendritic-web growth, and ribbon-to-ribbon growth, are comparatively ranked subject to criteria involving growth stability, sheet productivity, impurity effects, crystallinity, and solar cell results. The status of more rapid silicon ribbon growth techniques, such as horizontal ribbon growth and melt quenching, is also reviewed. The emphasis of the discussions is on examining the viability of these sheet materials as solar cell substrates for low-cost silicon photovoltaic systems.

Surek, T.

1980-12-01T23:59:59.000Z

417

Formation of amorphous metal alloys by chemical vapor deposition  

SciTech Connect

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.

Mullendore, Arthur W. (Sandia Park, NM)

1990-01-01T23:59:59.000Z

418

Microelectromechanical pump utilizing porous silicon  

DOE Patents (OSTI)

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.

Lantz, Jeffrey W. (Albuquerque, NM); Stalford, Harold L. (Norman, OK)

2011-07-19T23:59:59.000Z

419

Method for fabricating silicon cells  

DOE Patents (OSTI)

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.

Ruby, D.S.; Basore, P.A.; Schubert, W.K.

1998-08-11T23:59:59.000Z

420

Method for fabricating silicon cells  

DOE Patents (OSTI)

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.

Ruby, Douglas S. (Albuquerque, NM); Basore, Paul A. (Albuquerque, NM); Schubert, W. Kent (Albuquerque, NM)

1998-08-11T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Amorphization and precipitation within the amorphous layer induced by dry sliding wear of an Al-Si/SiCp composite material  

Science Conference Proceedings (OSTI)

Amorphization and precipitation have been observed within a surface mixed layer which was formed by unlubricated reciprocal sliding wear on the surface of Al-Si/SiCp composite. By using transmission electron microscopy, the characterizations of the amorphous phase and the crystal precipitates have been carried out. It has been identified that the precipitates possess tetragonal symmetry, and the lattice parameters of the precipitates have been determined. Internal twinning was also observed in the precipitate particles. EDS analysis indicates that the chemical composition of the precipitates was different from the amorphous phase. The results show that the precipitates might be produced in conjunction with the formation of the amorphous phase during the sliding wear. The formation mechanisms of the amorphous phase and the precipitates have been discussed in detail in terms of defects (i.e., dislocations and substructures) and thermodynamic changes induced by the unlubricated wear.

Li, X.Y.; Tandon, K.N. [Univ. of Manitoba, Winnipeg, Manitoba (Canada)

1996-09-01T23:59:59.000Z

422

Disilane versus monosilane: a comparison of the properties of glow-discharge a-Si:H films and solar cells  

SciTech Connect

The consequences of using disilane instead of silane for the glow-discharge deposition of a-Si:H solar cells have been studied. Deposition rates were increased fivefold by the use of disilane. The a-Si:H films have a higher hydrogen content, but otherwise are quite similar to silane produced films and possess the same type of gap states. Chlorosilanes, HCl, and oxysilanes were detected in the disilane by mass spectrometry and their influence on film and solar cell properties assessed. The problem of inadvertent dopant tails resulting from the higher deposition rate of the solar cells is identified.

Delahoy, A.E.; Kampas, F.J.; Corderman, R.R.; Vanier, P.E.; Griffith, R.W.

1982-01-01T23:59:59.000Z

423

Disilane versus monosilane: a comparison of the properties of glow-discharge a-Si:H Films and solar cells  

DOE Green Energy (OSTI)

The consequences of using disilane instead of silane for the glow-discharge deposition of a-Si:H solar cells have been studied. Deposition rates were increased fivefold by the use of disilane. The a-Si:H films have a higher hydrogen content, but otherwise are quite similar to silane produced films and possess the same type of gap states. Chlorosilanes, HCl, and oxysilanes were detected in the disilane by mass spectrometry and their influence on film and solar cell properties assessed. The problem of inadvertent dopant tails resulting from the higher deposition rate of the solar cells is identified.

Delahoy, A.E.; Corderman, R.R.; Griffith, R.W.; Kampas, F.J.; Vanier, P.E.

1982-09-01T23:59:59.000Z

424

Structural and electrical properties of trimethylboron-doped silicon nanowires  

SciTech Connect

Trimethylboron (TMB) was investigated as a p-type dopant source for the vapor-liquid-solid growth of boron-doped silicon nanowires (SiNWs). The boron concentration in the nanowires was measured using secondary ion mass spectrometry and results were compared for boron-doping using TMB and diborane (B{sub 2}H{sub 6}) sources. Boron concentrations ranging from 1x10{sup 18} to 4x10{sup 19} cm{sup -3} were obtained by varying the inlet dopant/SiH{sub 4} gas ratio. TEM characterization revealed that the B{sub 2}H{sub 6}-doped SiNWs consisted of a crystalline core with a thick amorphous Si coating, while the TMB-doped SiNWs were predominantly single crystal even at high boron concentrations. The difference in structural properties was attributed to the higher thermal stability and reduced reactivity of TMB compared to B{sub 2}H{sub 6}. Four-point resistivity and gate-dependent conductance measurements were used to confirm p-type conductivity in the TMB-doped nanowires and to investigate the effect of dopant concentration on nanowire resistivity.

Lew, K.-K.; Pan Ling; Bogart, Timothy E.; Dilts, Sarah M.; Dickey, Elizabeth C.; Redwing, Joan M.; Wang Yanfeng; Cabassi, Marco; Mayer, Theresa S.; Novak, Steven W. [Department of Materials Science and Engineering, Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Department of Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Evans East, East Windsor, New Jersey 08520 (United States)

2004-10-11T23:59:59.000Z

425

New amorphous forms of solid CO2 from ab initio molecular dynamics  

E-Print Network (OSTI)

By employing ab initio molecular dynamics simulations at constant pressure, we investigated behavior of amorphous carbon dioxide between 0-100 GPa and 200-500 K and found several new amorphous forms. We focused on evolution of the high-pressure tetrahedral amorphous form known as a-carbonia on its way down to zero pressure, where it eventually converts into a molecular amorphous solid. During decompression, two nonmolecular amorphous forms with different proportion of three and four-coordinated carbons and two mixed molecular-nonmolecular forms were observed. Transformation from a-carbonia to the molecular state appears to proceed discontinuously via several intermediate stages. This suggests that solid CO2 might belong to the group of materials exhibiting polyamorphism. We also studied relations of the amorphous forms to their crystalline counterparts. The predominantly four-coordinated a-carbonia is related to phase V according to their structural properties, while existence of the mixed forms may reflect h...

Plaienka, Duan

2013-01-01T23:59:59.000Z

426

Double quantum dot with tunable coupling in a Si MOS device with lateral geometry.  

Science Conference Proceedings (OSTI)

We report low-temperature transport measurements of a silicon metal-oxide-semiconductor (MOS) double quantum dot (DQD). In contrast to previously reported measurements of DQD's in Si MOS structures, our device has a lateral gate geometry very similar to that used by Petta et al. to demonstrate coherent manipulation of single electron spins. This gate design provides a high degree of tunability, allowing for independent control over individual dot occupation and tunnel barriers, as well as the ability to use nearby constrictions to sense dot charge occupation. Comparison of experimentally extracted capacitances between the dot and nearby gates with electrostatic modeling demonstrates the presence of disorder and the ability to partially compensate for this disorder by adjustment of gate voltages. We experimentally show gate-controlled tuning of the interdot coupling over a wide range of energies, an important step towards potential quantum computing applications.

Wendt, Joel Robert; Ten Eyck, Gregory A.; Childs, Kenton David; Tracy, Lisa A.; Pinilla, C. Borras (University of Oklahoma, Norman, OK); Eng, Kevin; Eriksson, Mark A. (University of Wisconsin-Madison, Madison, WI); Nordberg, Eric; Carroll, Malcolm S.; Stevens, J.; Young, Ralph Watson; Lilly, Michael Patrick; Stalford, Harold Lenn

2010-08-01T23:59:59.000Z

427

Continuous roll-to-roll a-Si photovoltaic manufacturing technology  

DOE Green Energy (OSTI)

This report describes work performed by ECD to advance its roll-to-roll, triple-junction photovoltaic manufacturing technologies; to reduce the module production costs; to increase the stabilized module performance; and to expand the commercial capacity utilizing ECD technology. The 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/W[sub p]. Major efforts during Phase I are (1) the optimization of the high-performance back-reflector system, (2) the optimization of a-Si-Ge narrow band-gap solar cell, and (3) the optimization of the stable efficiency of the module. The goal is to achieve a stable 8% efficient 0.3-m [times] 1.2-m (1-ft [times] 4-ft) module. Also, the efforts include work on a proprietary, high-deposition-rate, microwave plasma, CVD manufacturing technology; and on the investigation of material cost reduction.

Izu, M. (Energy Conversion Devices, Inc., Troy, MI (United States))

1993-04-01T23:59:59.000Z

428

Field-Annealed FeCo-Based Amorphous and Nanocrystalline Alloys ...  

Science Conference Proceedings (OSTI)

The saturation magnetic flux density for the optimum field annealed amorphous ... Current Status of Permanent Magnet Research and Market in China.

429

Synthesis of Amorphous Al-Co-Ce Alloys via Atomization and ...  

Science Conference Proceedings (OSTI)

Alternatively, complete amorphization of the Al9Co2 and Al11Ce3 compounds was achieved by mechanical milling the atomized powder. The effect of initial...

430

The Silicon Mine | Open Energy Information  

Open Energy Info (EERE)

Mine Mine Jump to: navigation, search Name The Silicon Mine Place Netherlands Sector Solar Product The Silicon Mine (TSM) will produce solar grade polysilicon suitable for the production of wafers or as the base material for the manufacture of solar cells. References The Silicon Mine[1] LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This article is a stub. You can help OpenEI by expanding it. The Silicon Mine is a company located in Netherlands . References ↑ "The Silicon Mine" Retrieved from "http://en.openei.org/w/index.php?title=The_Silicon_Mine&oldid=352196" Categories: Clean Energy Organizations Companies Organizations Stubs What links here Related changes Special pages Printable version Permanent link Browse properties

431

A study of signal generation and charge collection in a-Si:H diodes for radiation imaging  

SciTech Connect

Its high radiation resistivity and large-area capability are the expected advantages of this material together with its ability to provide a front-end readout electronics in the vicinity of the sensor element. Electrons and holes created by incoming charged particles, X-rays, {gamma} rays, are drifted by the electric field inside a-Si:H diodes and this carrier movement induces signal charges on electrodes. Charge collection and signal generation process are analyzed in terms of carrier mobilities, lifetimes and electric field. Charge collection in thick a-Si:H diodes is often limited by deep-level trapping of carriers during transit and a finite charge integration time required for single particle counting in some applications and sometimes by volume recombination of carriers for detecting heavily-ionizing particles such as {alpha} particles. The charge collection process is also strongly affected by the non-uniform electric field profiles in a-Si:H diodes caused by the fixed space charges inside the material under reverse-bias. Signal generation due to a weak light pulse irradiating each end of a thick diode is measured as a function of a reverse-bias and it gives a valuable information about the fixed space charges. Field profiles can be manipulated by either doping, electrode geometry, or combination of both to improve the charge collection process. One can apply a higher reverse-bias on a diode with an equivalent thickness by providing buffer layers at each end of the diode and thus suppressing soft breakdown phenomena. X-ray detection with a good sensitivity is demonstrated by an a-Si:H photodiode coupled to an evaporated CsI scintillator. The scintillation quality of evaporated CsI layers can be made almost identical to its single crystal counterpart. Fields of a-Si:H radiation detector application include high energy physics, medical imaging, materials science and life science. 78 refs., 68 figs., 11 tabs.

Fujieda, I.

1990-10-01T23:59:59.000Z

432

Process for strengthening silicon based ceramics  

DOE Patents (OSTI)

A process for strengthening silicon based ceramic monolithic materials and composite materials that contain silicon based ceramic reinforcing phases that requires that the ceramic be exposed to a wet hydrogen atmosphere at about 1400{degrees}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.

Kim, Hyoun-Ee; Moorhead, A.J.

1991-03-07T23:59:59.000Z

433

Toward accurate and large-scale silicon photonics  

E-Print Network (OSTI)

Silicon photonics, emerging from the interface of silicon technology and photonic technology, is expected to inherit the incredible integration ability of silicon technology that has boomed the microelectronic industry for ...

Sun, Jie, Ph.D. Massachusetts Institute of Technology

2013-01-01T23:59:59.000Z

434

Efficient light trapping structure in thin film silicon solar cells  

E-Print Network (OSTI)

Thin film silicon solar cells are believed to be promising candidates for continuing cost reduction in photovoltaic panels because silicon usage could be greatly reduced. Since silicon is an indirect bandgap semiconductor, ...

Sheng, Xing

435

Investigation of polarization anisotropy in individual porous silicon nanoparticles  

Science Conference Proceedings (OSTI)

Polarization anisotropy is investigated in single porous silicon nanoparticles containing multiple chromophores. Two forms of nanoparticle samples are studied; low current density (LCD) and high current density (HCD). Photoluminescence measurements reveal ... Keywords: Anisotropy, Photoluminescence, Polarization, Porous silicon, Silicon nanocrystal

Daniel J. Gargas; Donald J. Sirbuly; Michael D. Mason; Paul J. Carson; Steven K. Buratto

2008-09-01T23:59:59.000Z

436

Structural alloy with a protective coating containing silicon or silicon-oxide  

DOE Patents (OSTI)

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.

Natesan, K.

1992-01-01T23:59:59.000Z

437

Thin-film amorphous silicon alloy research partnership. Final technical progress report, 2 February 1995--28 February 1998  

Science Conference Proceedings (OSTI)

This report describes the status and accomplishments of work performed by United Solar Systems Corp. under this subcontract. Investigations were carried out on Ag/ZnO, Ag/TiO{sub 2}/ZnO and Ag/MgF{sub 2}/ZnO back reflectors to assess their suitability for use in cell structures. Arrays of high-efficiency component cells were made over 1-ft{sup 2} areas. Single-junction top cells were made with an average stabilized power density of 5.4 mW/cm{sup 2} measured under global AM1.5 illumination. Single-junction middle cells were optimized to give average stabilized power density of 3.6 mW/cm{sup 2} under global AM1.5 illumination with a cut-on filter with {lambda} > 530 nm. Arrays of high-efficiency triple-junction cells of 0.25-cm{sup 2} active area were fabricated over 1-ft{sup 2} area with average stabilized efficiency of 12% as measured under AM1.5 illumination. A triple-junction module of a 416-cm{sup 2} aperture area was fabricated with an initial efficiency of 11.7% and stabilized efficiency of 10.24%. A 922-cm{sup 2} aperture-area module exhibited an initial efficiency of 11.5%. The novel laser-drilling approach was used successfully to fabricate modules of 1-ft{sup 2} area with shadow loss of approximately 1%. Using this laser-drilling approach, an initial total-area efficiency of 11.5% was achieved in a triple-cell structure of 12.6 cm{sup 2} area. An initial total-area efficiency of 10.6% was achieved in a module of 300-cm{sup 2} area. Reliability studies based on NREL`s Interim Qualification Testing were carried out to confirm the suitability of the module encapsulation materials and processes. 29 figs., 17 tabs.

Guha, S. [United Solar Systems Corp., Troy, MI (United States)

1998-05-01T23:59:59.000Z

438

Innovative Characterization of Amorphous and Thin-Film Silicon for Improved Module Performance: 28 April 2005 - 15 September 2008  

DOE Green Energy (OSTI)

This report focuses on (1) characterizing nc-Si:H from United Solar; (2) studying Si,Ge:H alloys deposited by HWCVD; and (3) characterizing CIGS films and relating to cell performance parameters.

Cohen, J. D.

2009-12-01T23:59:59.000Z

439

Diagnostics of a glow discharge used to produce amorphous silicon films. Technical progress report, August 15, 1980-November 14, 1980  

SciTech Connect

Construction of the basic apparatus has been completed during this period, and many apparatus checks have been completed. Almost complete SiH/sub 4/ dissociation has been obtained in approx. 950 C ovens between the turbo and rough pumps, so that reliable, long-term operation is achieved. A base vacuum of approx. 10/sup -7/ Torr is achieved in the discharge chamber in a few hours, and approx. 10/sup -8/ overnight, so that gas-phase impurity levels as low as 10/sup -7/ are ready achievable. The SiH/sub 4/ inlet lines are entirely bakeable stainless steel and permanently closed to air, to maintain the tank purity of SiH/sub 4/. A distillation procedure to further clean the tank SiH/sub 4/ is under study. Thus we should be able to study the effects of very small, controlled levels of impurities. The discharge configurations are shown, and the ratios of Si/sub x/H/sub n//sup +/ fluxes for three types of discharges in pure SiH/sub 4/ are given. (WHK)

Gallagher, A.; Scott, J.

1980-01-01T23:59:59.000Z

440

Diagnostics of glow discharges used to produce hydrogenated amorphous silicon films. Subcontract report, 15 April 1984-14 April 1985  

SciTech Connect

Measurements of monosilane and disilane radicals were made at the surface of dc glow discharges (GD) in pure silane and silane-argon mixtures. These observations were interpreted as discharge kinetic models. It was inferred that the dominant radical, SiH/sub 3/, is produced in the gas and is primarily responsible for film growth. The heavier radicals observed in the gas appear to be a consequence of surface reactions, as is the disilane, a major product of the monosilane decomposition. A detailed model of the ion chemistry in the discharge was formulated to derive theoretical distributions of ions at the cathodes of low-pressure dc discharges. Chemical vapor deposition (CVD) rates of silane and disilane, measured previously in the laboratory, have now also been interpreted in detail to yield a self-consistent model for the CVD process. This model identifies and quantifies the role of H/sub 2/ as an inhibitor of silane GD and CVD deposition. Implications of these discoveries to deposition rates and film properties are discussed.

Gallagher, A.; Scott, J.

1985-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "amorphous silicon a-si" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.