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1

Amorphous Silicon  

Broader source: Energy.gov [DOE]

DOE has a proven track record of funding successes in amorphous silicon (a-Si)research. A list of current projects, summary of the benefits, and discussion on the production and manufacturing of...

2

Photocapacitance and hole drift mobility measurements in hydrogenated amorphous silicon (a-Si:H)  

SciTech Connect (OSTI)

The authors present measurements of the photocapacitance in hydrogenated amorphous silicon (a-Si:H) Schottky barrier diodes under reverse bias. A calculation relating photocapacitance to hole drift mobility measurements is also presented; the calculation incorporates the prominent dispersion effect for holes in a-Si:H usually attributed to valence bandtail trapping. The calculation accounts quantitatively for the magnitude and voltage-dependence of the photocapacitance.

Nurdjaja, I.; Schiff, E.A.

1997-07-01T23:59:59.000Z

3

Tritium in amorphous silicon  

SciTech Connect (OSTI)

Preliminary results on infrared and luminescence measurements of tritium incorporated amorphous silicon are reported. Tritium is an unstable isotope that readily substitutes hydrogen in the amorphous silicon network. Due to its greater mass, bonded tritium is found to introduce new stretching modes in the infrared spectrum. Inelastic collisions between the beta particles, produced as a result of tritium decay, and the amorphous silicon network, results in the generation of excess electron-hole pairs. Radiative recombination of these carriers is observed.

Sidhu, L.S.; Kosteski, T.; O`Leary, S.K.; Gaspari, F.; Zukotynski, S. [Univ. of Toronto, Ontario (Canada). Dept. of Electrical and Computer Engineering; Kherani, N.P.; Shmadya, W. [Ontario Hydro Technologies, Toronto, Ontario (Canada)

1996-12-31T23:59:59.000Z

4

Bonding defects in hydrogenated amorphous silicon  

SciTech Connect (OSTI)

A mechanism for charged-carrier-trapping-induced defect metastability in hydrogenated amorphous silicon (a-Si:H) and in hydrogenated amorphous silicon alloys containing relatively high concentrations of oxygen and/or nitrogen atoms (a-Si:X:H, X = O or N) is described. The experimental results that identified this defect metastability mechanism were (i) differences in the Staebler-Wronski effect in a-Si:H and a-Si:N:H alloys prepared from N{sub 2} and NH{sub 3} source gases by remote plasma-enhanced chemical-vapor deposition, and (ii) differences in defect generation at N-atom terminated Si-SiO{sub 2} interfaces prepared from NH{sub 3} and N{sub 2}O.

Lucovsky, G.; Yang, H. [North Carolina State Univ., Raleigh, NC (United States)

1996-12-31T23:59:59.000Z

5

Amorphous and microcrystalline silicon technology -- 1998  

SciTech Connect (OSTI)

Although this new volume from MRS is the 16th in a long-standing and successful series, the focus is no longer limited to hydrogenated amorphous silicon (a-Si:H). The distinction between short- and medium-range order, and between homogeneous and heterogeneous semiconductor materials, is indeed too difficult to maintain. Instead, the volume covers amorphous and microcrystalline silicon from materials physics to new applications. Papers from a joint session with a symposium on ``Flat-Panel Display Materials and Large-Area Processes`` are included. The volume also features special focused sessions on heterogeneous materials, color sensors and radiation imaging, and parameter extraction and device modeling. Topics include: amorphous and polycrystalline thin-film transistors; solar cells; color and X-ray sensors, novel devices, luminescence and sensitization; device modeling and parameter extraction; growth, alloys and clathrates; metastability, hydrogen, atomic and electronic structure; defects and charge transport; and heterogeneous silicon--formation, properties and devices. It includes 152 papers.

Schropp, R. [ed.] [Utrecht Univ. (Netherlands); Branz, H.M. [ed.] [National Renewable Energy Lab., Golden, CO (United States); Shimizu, Isamu [ed.] [Tokyo Inst. of Tech. (Japan); Wagner, S. [ed.] [Princeton Univ., NJ (United States); Hack, M. [ed.

1999-08-01T23:59:59.000Z

6

Structural relaxation of vacancies in amorphous silicon  

SciTech Connect (OSTI)

The authors have studied the structural relaxation of vacancies in amorphous silicon (a-Si) using a tight-binding molecular-dynamics method. The most significant difference between vacancies in a-Si and those in crystalline silicon (c-Si) is that the deep gap states do not show up in a-Si. This difference is explained through the unusual behavior of the structural relaxation near the vacancies in a-Si, which enhances the sp{sup 2} + p bonding near the band edges. They have also observed that the vacancies do not migrate below 450 K although some of them can still be annihilated, particularly at high defect density due to large structural relaxation.

Kim, E.; Lee, Y.H.; Chen, C.; Pang, T.

1997-07-01T23:59:59.000Z

7

Improvement of pin-type amorphous silicon solar cell performance by employing double silicon-carbide p-layer structure  

E-Print Network [OSTI]

Improvement of pin-type amorphous silicon solar cell performance by employing double silicon-carbide Received 30 October 2003; accepted 18 November 2003 We investigated a double silicon-carbide p-layer structure consisting of a undiluted p-type amorphous silicon-carbide (p-a-SiC:H) window layer and a hydrogen

Kim, Yong Jung

8

Technological development for commercialization of amorphous silicon based multijunction modules  

SciTech Connect (OSTI)

Some of the significant steps in technological development for large-scale commercialization of amorphous silicon (a-Si:H) based multijunction photovoltaic modules are presented. These developments are establishing a high quality baseline process for manufacturing large-area ({approximately}8 ft{sup 2}) a-Si:H/a-SiGe:H tandem junction modules with improved stabilized conversion efficiency, throughput, yield, and reduced materials usage.

Yang, L.; Bennett, M.; Chen, L. [Solarex, Newtown, PA (United States)] [and others

1996-12-31T23:59:59.000Z

9

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

10

Amorphous silicon/polyaniline heterojunction solar cells: Fermi levels and open-circuit voltages  

E-Print Network [OSTI]

these open-circuit voltages are lower than for the best a-Si:H cells utilizing nanocrystalline Si or a reports on conducting polymer/ amorphous silicon (a-Si:H) structures [1­4] and conduct- ing polymer/crystalline silicon (c-Si) structures [5,6]. In this paper, we report our research on polyaniline (PANI)/a-Si:H

Schiff, Eric A.

11

Electroabsorption measurements and built-in potentials in amorphous silicon pin solar cells  

E-Print Network [OSTI]

and the capacitance of such devices. We apply this technique to hydrogenated amorphous silicon a-Si:H -based solar-6951 96 04246-5 The internal electric fields of amporphous silicon a- Si:H -based p­i­n solar cells on electroluminescent organic heterostructure diodes . We con- firmed this interpretation by studying a-Si:H n

Schiff, Eric A.

12

Short-and intermediate-range structural correlations in amorphous silicon carbide: A molecular dynamics study  

E-Print Network [OSTI]

Short- and intermediate-range structural correlations in amorphous silicon carbide: A molecular-range structural correlations in amorphous silicon carbide a-SiC are studied in terms of partial pair distributions.43.Dq, 61.43.Bn, 61.66.Dk, 81.05.Gc I. INTRODUCTION Silicon carbide SiC has been receiving increasing

Southern California, University of

13

Hydrogenated amorphous silicon-germanium alloys  

SciTech Connect (OSTI)

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

Amorphous silicon passivated contacts for diffused junction silicon solar cells  

Science Journals Connector (OSTI)

Carrier recombination at the metal contacts is a major obstacle in the development of high-performance crystalline silicon homojunction solar cells. To address this issue we insert thin intrinsic hydrogenated amorphous silicon [a-Si:H(i)] passivating films between the dopant-diffused silicon surface and aluminum contacts. We find that with increasing a-Si:H(i) interlayer thickness (from 0 to 16?nm) the recombination loss at metal-contacted phosphorus (n+) and boron (p+) diffused surfaces decreases by factors of ?25 and ?10 respectively. Conversely the contact resistivity increases in both cases before saturating to still acceptable values of ? 50 m? cm2 for n+ and ?100 m? cm2 for p+ surfaces. Carrier transport towards the contacts likely occurs by a combination of carrier tunneling and aluminum spiking through the a-Si:H(i) layer as supported by scanning transmission electron microscopyenergy dispersive x-ray maps. We explain the superior contact selectivity obtained on n+ surfaces by more favorable band offsets and capture cross section ratios of recombination centers at the c-Si/a-Si:H(i) interface.

J. Bullock; A. Cuevas

2014-01-01T23:59:59.000Z

17

Amorphous silicon passivated contacts for diffused junction silicon solar cells  

SciTech Connect (OSTI)

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

Bullock, J., E-mail: james.bullock@anu.edu.au; Yan, D.; Wan, Y.; Cuevas, A. [Research School of Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Demaurex, B.; Hessler-Wyser, A.; De Wolf, S. [cole Polytechnique Fdrale de Lausanne (EPFL), Institute of micro engineering (IMT), Photovoltaics and Thin Film Electronic Laboratory, Maladire 71, CH-200 Neuchtel (Switzerland)

2014-04-28T23:59:59.000Z

18

Optical absorption in amorphous silicon  

SciTech Connect (OSTI)

The role that disorder plays in shaping the form of the optical absorption spectrum of hydrogenated amorphous silicon is investigated. Disorder leads to a redistribution of states, which both reduces the Tauc gap and broadens the absorption tail. The observed relationship between the Tauc gap and the breadth of the absorption tail is thus explained.

O`Leary, S.K.; Zukotynski, S.; Perz, J.M.; Sidhu, L.S. [Univ. of Toronto, Ontario (Canada). Dept. of Electrical and Computer Engineering

1996-12-31T23:59:59.000Z

19

Amorphous Silicon Based Neutron Detector  

SciTech Connect (OSTI)

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

20

A chemical bonding model for photo-induced defects in hydrogenated amorphous silicon (a-Si:H): Intrinsic and extrinsic reaction pathways  

SciTech Connect (OSTI)

In device grade a-Si:H photo- or light-induced defect generation is an intrinsic effect for impurity concentrations of oxygen and nitrogen below about 10{sup 19} to 10{sup 20} cm{sup {minus}3}; however, at higher concentrations it increases with increasing impurity content. Charged defect configurations are identified by empirical chemistry and are studied by ab initio calculations. This paper addresses: (1) the chemical stability of charged defects; (2) the reaction pathways for defect metastability; and (3) the transition between extrinsic and intrinsic behavior.

Lucovsky, G.; Yang, H.

1997-07-01T23:59:59.000Z

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.


21

Narrow band gap amorphous silicon semiconductors  

DOE Patents [OSTI]

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

Madan, A.; Mahan, A.H.

1985-01-10T23:59:59.000Z

22

Atomistic modeling of amorphous silicon carbide using a bond...  

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

modeling of amorphous silicon carbide using a bond-order potential. Atomistic modeling of amorphous silicon carbide using a bond-order potential. Abstract: Molecular dynamics...

23

Irradiation-induced defect clustering and amorphization in silicon...  

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

Irradiation-induced defect clustering and amorphization in silicon carbide. Irradiation-induced defect clustering and amorphization in silicon carbide. Abstract: Previous computer...

24

Exciton harvesting, charge transfer, and charge-carrier transport in amorphous-silicon nanopillar/polymer hybrid solar cells  

E-Print Network [OSTI]

report on the device physics of nanostructured amorphous-silicon a-Si:H /polymer hybrid solar cells and nanostructured a-Si:H/polymer systems. We find that strong energy transfer occurs in the a-Si:H/MEH-PPV system. However, inefficient hole transfer from the a-Si:H to the polymers renders negligible photocurrent

McGehee, Michael

25

Amorphous silicon thin film transistor as nonvolatile device.  

E-Print Network [OSTI]

particles before loaded into the deposition chamber. 2.2.2. Equipment for Plasma Processes Plasma-Enhanced Chemical Vapor...: Dr. Yue Kuo n-channel and p-channel amorphous-silicon thin-film transistors (a-Si:H TFTs) with copper electrodes prepared by a novel plasma etching process have been fabricated and studied. Their characteristics are similar to those of TFTs...

Nominanda, Helinda

2008-10-10T23:59:59.000Z

26

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

27

Cooling of hot electrons in amorphous silicon  

SciTech Connect (OSTI)

Measurements of the cooling rate of hot carriers in amorphous silicon are made with a two-pump, one-probe technique. The experiment is simulated with a rate-equation model describing the energy transfer between a population of hot carriers and the lattice. An energy transfer rate proportional to the temperature difference is found to be consistent with the experimental data while an energy transfer independent of the temperature difference is not. This contrasts with the situation in crystalline silicon. The measured cooling rates are sufficient to explain the difficulty in observing avalanche effects in amorphous silicon.

Vanderhaghen, R.; Hulin, D.; Cuzeau, S.; White, J.O.

1997-07-01T23:59:59.000Z

28

Properties of hydrogenated amorphous silicon prepared by chemical vapor deposition  

SciTech Connect (OSTI)

Hydrogenated amorphous silicon (a-Si:H) films were prepared by chemical vapor deposition (CVD) from mixtures of silane, disilane, trisilane, and higher polysilanes in hydrogen carrier gas at 1 atm total pressure, at substrate temperatures from 420--530 /sup 0/C. Experimental parameters are explained and properties as a function of these parameters are shown. The measurements include hydrogen content (by IR), optical, electrical, and photovoltaic properties of the material. In most respects, the CVD material closely resembles the a-Si:H usually prepared by glow discharge. The following differences have been noted: (1) the CVD a-Si:H shows no IR absorption at 840--850 cm/sup -1/, which is consistent with the expected better thermal stability of the CVD material because of the much higher substrate temperatures in the CVD process than in the glow discharge process. (2) The band gap of CVD a-Si:H is lower by about 0.1 eV than glow discharge a-Si:H of the same hydrogen content. Thus, the band gap of CVD a-Si:H is better matched to the solar spectrum than is glow discharge a-Si:H. (3) All three IR absorption bands due to hydrogen are about 20% narrower in the CVD a-Si:H, suggesting a simpler structure. (4) The temperature dependence of the dark conductivity of CVD a-Si:H fits a curve for a single activation energy, in contrast to the more complicated temperature dependence often found in glow discharge a-Si:H, in which two different activation energies are seen at high and low temperatures. This suggests that the conduction mechanism is also simpler in the CVD a-Si:H.

Ellis, F.B. Jr.; Gordon, R.G.; Paul, W.; Yacobi, B.G.

1984-06-15T23:59:59.000Z

29

Amorphous silicon detectors in positron emission tomography  

SciTech Connect (OSTI)

The physics of the detection process is studied and the performances of different Positron Emission Tomography (PET) system are evaluated by theoretical calculation and/or Monte Carlo Simulation (using the EGS code) in this paper, whose table of contents can be summarized as follows: a brief introduction to amorphous silicon detectors and some useful equation is presented; a Tantalum/Amorphous Silicon PET project is studied and the efficiency of the systems is studied by Monte Carlo Simulation; two similar CsI/Amorphous Silicon PET projects are presented and their efficiency and spatial resolution are studied by Monte Carlo Simulation, light yield and time characteristics of the scintillation light are discussed for different scintillators; some experimental result on light yield measurements are presented; a Xenon/Amorphous Silicon PET is presented, the physical mechanism of scintillation in Xenon is explained, a theoretical estimation of total light yield in Xenon and the resulting efficiency is discussed altogether with some consideration of the time resolution of the system; the amorphous silicon integrated electronics is presented, total noise and time resolution are evaluated in each of our applications; the merit parameters {epsilon}{sup 2}{tau}'s are evaluated and compared with other PET systems and conclusions are drawn; and a complete reference list for Xenon scintillation light physics and its applications is presented altogether with the listing of the developed simulation programs.

Conti, M. (Istituto Nazionale di Fisica Nucleare, Pisa (Italy) Lawrence Berkeley Lab., CA (USA)); Perez-Mendez, V. (Lawrence Berkeley Lab., CA (USA))

1989-12-01T23:59:59.000Z

30

AMORPHOUS SILICON-BASED MINIMODULES WITH SILICONE ELASTOMER ENCAPSULATION  

E-Print Network [OSTI]

fabricated one and two cell, amorphous silicon based mini-modules encapsulated with a modern silicone. The first module consisted of a single cell with a current collecting grid and bus bars on two sides of the cell. The current collecting grid used a spacing of 1 cm. 250 µm diameter tinned copper wire was used

Deng, Xunming

31

Amorphization of Silicon Carbide by Carbon Displacement. | EMSL  

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

of Silicon Carbide by Carbon Displacement. Amorphization of Silicon Carbide by Carbon Displacement. Abstract: We have used molecular dynamics simulations to examine the possibility...

32

Optical bandgap of ultra-thin amorphous silicon films deposited on crystalline silicon by PECVD  

SciTech Connect (OSTI)

An optical study based on spectroscopic ellipsometry, performed on ultrathin hydrogenated amorphous silicon (a-Si:H) layers, is presented in this work. Ultrathin layers of intrinsic amorphous silicon have been deposited on n-type mono-crystalline silicon (c-Si) wafers by plasma enhanced chemical vapor deposition (PECVD). The layer thicknesses along with their optical properties including their refractive index and optical loss- were characterized by spectroscopic ellipsometry (SE) in a wavelength range from 250 nm to 850 nm. The data was fitted to a Tauc-Lorentz optical model and the fitting parameters were extracted and used to compute the refractive index, extinction coefficient and optical bandgap. Furthermore, the a-Si:H film grown on silicon was etched at a controlled rate using a TMAH solution prepared at room temperature. The optical properties along with the Tauc-Lorentz fitting parameters were extracted from the model as the film thickness was reduced. The etch rate for ultrathin a-Si:H layers in TMAH at room temperature was found to slow down drastically as the c-Si interface is approached. From the Tauc-Lorentz parameters obtained from SE, it was found that the a-Si film exhibited properties that evolved with thickness suggesting that the deposited film is non-homogeneous across its depth. It was also found that the degree of crystallinity and optical (Tauc) bandgap increased as the layers were reduced in thickness and coming closer to the c-Si substrate interface, suggesting the presence of nano-structured clusters mixed into the amorphous phase for the region close to the crystalline silicon substrate. Further results from Atomic Force Microscopy and Transmission Electron Microscopy confirmed the presence of an interfacial transitional layer between the amorphous film and the underlying substrate showing silicon nano-crystalline enclosures that can lead to quantum confinement effects. Quantum confinement is suggested to be the cause of the observed increase in the optical bandgap of a-Si:H films close to the a-Si:H/cSi interface.

Abdulraheem, Yaser, E-mail: yaser.abdulraheem@kuniv.edu.kw [Electrical Engineering Department, College of Engineering and Petroleum, Kuwait University. P.O. Box 5969, 13060 Safat (Kuwait); Gordon, Ivan; Bearda, Twan; Meddeb, Hosny; Poortmans, Jozef [IMEC, Kapeldreef 75, 3001, Leuven (Belgium)

2014-05-15T23:59:59.000Z

33

Muon States in Polycrystalline and Amorphous Silicon [and Discussion  

Science Journals Connector (OSTI)

15 February 1995 research-article Muon States in Polycrystalline and Amorphous Silicon [and Discussion] E. A. Davis A. Singh S. F. J. Cox A. M. Stoneham M. Symons Muons implanted into polycrystalline and amorphous silicon have been...

1995-01-01T23:59:59.000Z

34

Spin-dependent processes in amorphous silicon-rich silicon-nitride S.-Y. Lee,1  

E-Print Network [OSTI]

diodes9 and a-Si:H solar cells.10 Fol- lowing coherent manipulation of paramagnetic centers, tran- sient-band , TSAMPLE=15 K. Dark and illuminated IV curves of the p-i-n devices were measured at room temperature and T amorphous silicon nitride a-SiNx:H has been used widely as a dielectric for thin-film transistors,1 solar

McCamey, Dane

35

E-Print Network 3.0 - amorphous silicon carbon Sample Search...  

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

is changing from a cross-linked diamond-like carbon material to an amorphous silicon carbide material... with silicon. 1. Introduction Amorphous hydrogenated silicon carbide...

36

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

E-Print Network [OSTI]

. Figure 3-1 IV curve of a UT fabricated triple cell, showing 12.7% initial, active-area efficiency. Figure1 High Efficiency and High Rate Deposited Amorphous Silicon-Based Solar Cells PHASE I Annual-junction a-Si Solar Cells with Heavily Doped Thin Interface Layers at the Tunnel Junctions Section 4 High

Deng, Xunming

37

Chemical vapor deposition of hydrogenated amorphous silicon from disilane  

SciTech Connect (OSTI)

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

38

CVD amorphous silicon solar cells  

SciTech Connect (OSTI)

Development of all-CVD TCO/p-i-n/metal/substrate a-Si devices made by CVD from disilane is reported. The reactor and conditions for depositing device quality CVD a-Si at growth rates up to 10 A/sec are described. Conductivity, optical properties and density of states of CVD i layers are described. Photovoltaic device characteristics of all - CVD and hybrid (CVD/GD) pin and nip devices are compared. Efficiencies up to 4% were achieved. An analysis of collection efficiency indicates a hole ..mu../tau/ of 1 - 4 X 10/sup -9/ cm/sup 2//V. Cell performance is consistent with a series connected double junction model.

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

1984-05-01T23:59:59.000Z

39

Ion bombardment and disorder in amorphous silicon  

SciTech Connect (OSTI)

The effect of ion bombardment during growth on the structural and optical properties of amorphous silicon are presented. Two series of films were deposited under electrically grounded and positively biased substrate conditions. The biased samples displayed lower growth rates and increased hydrogen content relative to grounded counterparts. The film structure was examined using Raman spectroscopy. The transverse optic like phonon band position was used as a parameter to characterize network order. Biased samples displayed an increased order of the amorphous network relative to grounded samples. Furthermore, biased samples exhibited a larger optical gap. These results are correlated and attributed to reduced ion bombardment effects.

Sidhu, L.S.; Gaspari, F.; Zukotynski, S.

1997-07-01T23:59:59.000Z

40

Deuterium in crystalline and amorphous silicon  

SciTech Connect (OSTI)

The authors report deuteron magnetic resonance (DMR) measurements on aged deuterium-implanted single crystal n-type silicon and comparisons with amorphous silicon spectra. The sample film was prepared six years ago by deuteration from a-D{sub 2} plasma and evaluated by a variety of experimental methods. Deuterium has been evolving with time and the present DMR signal shows a smaller deuteron population. A doublet from Si-D configurations along (111) has decreased more than have central molecular DMR components, which include 47 and 12 kHz FWHM gaussians. Transient DMR magnetization recoveries indicate spin lattice relaxation to para-D{sub 2} relaxation centers.

Borzi, R.; Ma, H.; Fedders, P.A.; Leopold, D.J.; Norberg, R.E.; Boyce, J.B.; Johnson, N.M.; Ready, S.E.; Walker, J.

1997-07-01T23:59:59.000Z

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.


41

Autocompensation in doped amorphous silicon  

Science Journals Connector (OSTI)

Studies based predominantly on luminescence and electron spin resonance provide strong evidence for defect formation concomitant with doping of glow discharge produced a?Si:H. In samples doped with boron or phosphorus the increase of non?radiative recombination observed in luminescence correlates with the increase of the dangling bond signal seen in light?induced ESR. This directly indicates an increase in the number of dangling?bond?like centers with doping. Compensation allows the Fermi level and dopant levels to be varied independently. In compensated samples with EF near midgap the number of dangling bond centers is reduced. An autocompensation mechanism is proposed to explain this Fermi level?dependent defect formation.

D. K. Biegelsen; R. A. Street; J. C. Knights

1981-01-01T23:59:59.000Z

42

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...

Nominanda, Helinda

2012-06-07T23:59:59.000Z

43

Exciton splitting and carrier transport across the amorphous-silicon/polymer solar cell interface  

Science Journals Connector (OSTI)

The authors study exciton splitting at the interface of bilayer hybridsolar cells to better understand the physics controlling organic-inorganicdevice performance. Hydrogenated amorphous silicon ( a - Si : H ) ? poly ( 3 - hexylthiophene ) (P3HT) and a - Si : H ? poly ( 2 - methoxy - 5 - ( 2 ? - ethyl - hexyloxy ) - 1 4 - phenylenevinylene ) (MEH-PPV) solar cells show photoresponse dominated by exciton production in the polymer. The a - Si : H ? P 3 HT devices are nearly as efficient as titania/P3HT cells. However the a - Si : H ? MEH - PPV system has much lower photocurrent than a - Si : H ? P 3 HT likely due to inefficient hole transfer back to the MEH-PPV after energy transfer from MEH-PPV to a - Si : H .

Vignesh Gowrishankar; Shawn R. Scully; Michael D. McGehee; Qi Wang; Howard M. Branz

2006-01-01T23:59:59.000Z

44

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

45

Research on stable, high-efficiency amorphous silicon multijunction modules  

SciTech Connect (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

46

Monolithic amorphous silicon modules on continuous polymer substrate  

SciTech Connect (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

47

Laser induced melting and crystallization of boron doped amorphous silicon  

SciTech Connect (OSTI)

Transient reflectivity experiments have been performed to measure the dynamics of laser-induced melting of amorphous silicon (a-Si) and the crystallization to {micro}c-Si of films with different thicknesses on Corning 7059 glass. The laser-induced melting takes place with a velocity of 13 to 24 m/s, while the solidification is about a factor 10 slower. The crystallization starts at the Si/glass interface and at the surface. In the center of the films Si remains liquid for an extended period of time. The crystallization dynamics point towards an heterogeneous morphology of laser-crystallized Si, where the surface and the interface layers are composed of small grains and the bulk of larger grains.

Nebel, C.E.; Schoeniger, S.; Dahlheimer, B.; Stutzmann, M.

1997-07-01T23:59:59.000Z

48

Antimony Induced Crystallization of Amorphous Silicon  

Science Journals Connector (OSTI)

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1?m were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.

Y. Wang; H.Z. Li; C.N. Yu; G.M. Wu; I. Gordon; P. Schattschneider; O. Van Der Biest

2007-01-01T23:59:59.000Z

49

Subtleties of capacitance transients in amorphous silicon  

SciTech Connect (OSTI)

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

Crandall, R.S. [National Renewable Energy Lab., Golden, CO (United States); Lips, K. [Hahn-Meitner-Inst., Berlin (Germany)

1996-12-31T23:59:59.000Z

50

E-Print Network 3.0 - amorphous silicon solar Sample Search Results  

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

for a research organization in the optimization of the amorphous silicon solar cell... photovoltaics on flexible substrates. Managed amorphous silicon research program...

51

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

52

Hydrogen plasma enhanced crystallization of hydrogenated amorphous silicon films  

E-Print Network [OSTI]

Hydrogen plasma enhanced crystallization of hydrogenated amorphous silicon films K. Pangal,a) J. C August 1998; accepted for publication 21 October 1998 We report that a room temperature hydrogen plasma thermal crystallization of amorphous silicon time by a factor of five. Exposure to hydrogen plasma reduces

53

An infrared and luminescence study of tritiated amorphous silicon  

SciTech Connect (OSTI)

Tritium has been incorporated into amorphous silicon. Infrared spectroscopy shows new infrared vibration modes due to silicon-tritium (Si-T) bonds in the amorphous silicon network. Si-T vibration frequencies are related to Si-H vibration frequencies by simple mass relationships. Inelastic collisions of {beta} particles, produced as a result of tritium decay, with the amorphous silicon network results in the generation of electron-hole pairs. Radiative recombination of these carriers is observed. Dangling bonds associated with the tritium decay reduce luminescence efficiency.

Sidhu, L.S.; Kosteski, T.; Kherani, N.P.; Gaspari, F.; Zukotynski, S.; Shmayda, W.

1997-07-01T23:59:59.000Z

54

Hydrogenated amorphous silicon produced by pyrolysis and photolysis of disilane  

SciTech Connect (OSTI)

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

55

High efficiency neutron sensitive amorphous silicon pixel detectors  

SciTech Connect (OSTI)

A multi-layer a-Si:H based thermal neutron detector was designed, fabricated and simulated by Monte Carlo method. The detector consists of two PECVD deposited a-Si:H pin detectors interfaced with coated layers of Gd, as a thermal neutron converter. Simulation results indicate that a detector consisting of 2 Gd films with thicknesses of 2 and 4 {mu}m, sandwiched properly with two layers of sufficiently thick ({approximately}30{mu}m) amorphous silicon diodes, has the optimum parameters. The detectors have an intrinsic efficiency of about 42% at a threshold setting of 7000 electrons, with an expected average signal size of {approximately}12000 electrons which is well above the noise. This efficiency will be further increased to nearly 63%, if we use Gd with 50% enrichment in {sup 157}Gd. We can fabricate position sensitive detectors with spatial resolution of 300 {mu}m with gamma sensitivity of {approximately}1 {times} 10{sup {minus}5}. These detectors are highly radiation resistant and are good candidates for use in various application, where high efficiency, high resolution, gamma insensitive position sensitive neutron detectors are needed.

Mireshghi, A.; Cho, G.; Drewery, J.S.; Hong, W.S.; Jing, T.; Lee, H.; Kaplan, S.N.; Perez-Mendez, V.

1993-11-01T23:59:59.000Z

56

RF Sputtering for preparing substantially pure amorphous silicon monohydride  

DOE Patents [OSTI]

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

Jeffrey, Frank R. (Ames, IA); Shanks, Howard R. (Ames, IA)

1982-10-12T23:59:59.000Z

57

Direct-current substrate bias effects on amorphous silicon sputter-deposited films for thin film transistor fabrication  

SciTech Connect (OSTI)

The effect that direct current (dc) substrate bias has on radio frequency-sputter-deposited amorphous silicon (a-Si) films has been investigated. The substrate bias produces a denser a-Si film with fewer defects compared to unbiased films. The reduced number of defects results in a higher resistivity because defect-mediated conduction paths are reduced. Thin film transistors (TFTs) that were completely sputter deposited were fabricated and characterized. The TFT with the biased a-Si film showed lower leakage (off-state) current, higher on/off current ratio, and higher transconductance (field effect mobility) than the TFT with the unbiased a-Si film.

Jun, Seung-Ik; Rack, Philip D.; McKnight, Timothy E.; Melechko, Anatoli V.; Simpson, Michael L. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996-2200 (United States); Molecular Scale Engineering and Nanoscale Technologies Research Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2005-09-26T23:59:59.000Z

58

High-rate deposition of hydrogenated amorphous silicon films and devices  

SciTech Connect (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

59

In Situ Hydrogenation of Amorphous Silicon Prepared by Thermal Decomposition of Disilane  

Science Journals Connector (OSTI)

Thin hydrogenated amorphous silicon (a-Si:H) layers with thicknesses of 90-600 ? grown by thermal decomposition of disilane were treated with rf hydrogen plasma just after deposition at the same temperature (430-440?C). During this process (referred to as in situ hydrogenation), atomic hydrogen passivates defects, and the effective thickness of this passivated layer is estimated to be 220 ?. Atomic hydrogen also induces structural relaxation of the Si network even in a-Si:H deposited at high temperature (>400?C) while the change of bonded hydrogen content is rather small in in situ hydrogenation.

Mitsuyuki Yamanaka; Yutaka Hayashi; Isao Sakata

1993-01-01T23:59:59.000Z

60

Process for producing amorphous and crystalline silicon nitride  

DOE Patents [OSTI]

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

Morgan, Peter E. D. (Thousand Oaks, CA); Pugar, Eloise A. (Newbury Park, CA)

1985-01-01T23:59:59.000Z

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.


61

Solar-to-Hydrogen Photovoltaic/Photoelectrochemical Devices Using Amorphous Silicon Carbide as the Photoelectrode  

SciTech Connect (OSTI)

We report the use of hydrogenated amorphous silicon carbide (a-SiC:H) prepared by plasma enhanced chemical vapor deposition (PECVD) as the photoelectrode in an integrated 'hybrid' photoelectrochemical (PEC) cell to produce hydrogen directly from water using sunlight. Results on the durability of hydrogenated amorphous silicon carbide (a-SiC:H) photoelectrodes in an electrolyte are presented. In a pH2 electrolyte, the a-SiC:H photoelectrode exhibits excellent stability for 100 hour test so far performed. A photocurrent onset shift (anodically) after a 24- or 100-hour durability test in electrolyte is observed, likely due to changes in the surface chemical structure of the a-SiC:H photoelectrode. It is also observed that a thin SiOx layer native to the air exposed surface of the a-SiC:H affects the photocurrent and the its onset shift. Finally, approaches for eliminating the external bias voltage and enhancing the solar-to-hydrogen efficiency in a PV/PEC hybrid structure to achieve {>=} 10% are presented.

Hu, J.; Zhu, F.; Matulionis, I.; Kunrath, A.; Deutsch, T.; Kuritzky, L.; Miller, E.; Madan, A.

2008-01-01T23:59:59.000Z

62

Broadband, stable and highly coherent supercontinuum generation at telecommunication wavelengths in an hydrogenated amorphous silicon waveguide  

E-Print Network [OSTI]

Hydrogenated amorphous silicon (a:Si-H) has recently been recognized as a highly nonlinear CMOS compatible photonic platform. We experimentally demonstrate the generation of a supercontinuum (SC) spanning over 500 nm in a-Si:H photonic wire waveguide at telecommunication wavelengths using femtosecond input pulse with energy lower than 5 pJ. Numerical modeling of pulse propagation in the waveguide, based on the experimentally characterized dispersion profile, shows that the supercontinuum is the result of soliton fission and dispersive wave generation. It is demonstrated that the SC is highly coherent and that the waveguides do not suffer from material degradation under femtosecond pulse illumination. Finally, a direct comparison of SC generation in c-Si and a-Si:H waveguides confirms the higher performances of a-Si:H over c-Si for broadband low power SC generation at telecommunication wavelengths.

Leo, F; Kuyken, B; Roelkens, G; Gorza, S -P

2014-01-01T23:59:59.000Z

63

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

SciTech Connect (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

64

Hydrogenated amorphous silicon films prepared by glow discharge of disilane  

SciTech Connect (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

65

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

SciTech Connect (OSTI)

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

66

Nuclear magnetic resonance studies of hydrogen in amorphous silicon  

SciTech Connect (OSTI)

Proton and deuteron NMR in hydrogenated amorphous silicon yield quantitative measures of species-specific structural configurations and their dynamics. Populations of silicon-bonded and molecular hydrogens correlate with photovoltaic quality, doping, illumination/dark anneal sequences, and with infrared and other characterizations. High quality films contain substantial populations of nanovoid-trapped molecular hydrogen.

Norberg, R.E.; Fedders, P.A.; Leopold, D.J. [Washington Univ., St. Louis, MO (United States). Dept. of Physics

1996-12-31T23:59:59.000Z

67

E-Print Network 3.0 - amorphous silicon-carbon alloys Sample...  

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

1. On the one hand, stable amorphous alloy which leads to the change... of eutectic alloy amorphous silicon film. (b) SAD pattern of ... Source: Grigoriev, Alexei -...

68

Amorphous and microcrystalline silicon technology--1997. Materials Research Society symposium proceedings, Volume 467  

SciTech Connect (OSTI)

This book was divided into the following parts: Staebler-Wronski and Fundamental Defect Studies in Amorphous Silicon; The Story of Hydrogen in Amorphous Silicon; Photoelectric Properties of Amorphous Silicon; Deposition and Properties of Microcrystalline Silicon; Deposition Studies for Amorphous Silicon and Related Materials; Solar Cells; Thin-Film Transistors; and Sensors and Novel Device Concepts. Separate abstracts were prepared for most of the papers in the volume.

Wagner, S.; Hack, M.; Schiff, E.A.; Schropp, R.; Shimizu, I. [eds.

1997-07-01T23:59:59.000Z

69

Low-temperature solid-phase crystallization of amorphous silicon thin films deposited by rf magnetron sputtering with substrate bias  

SciTech Connect (OSTI)

The crystallization properties of amorphous silicon (a-Si) thin film deposited by rf magnetron sputter deposition with substrate bias have been thoroughly characterized. The crystallization kinetics for films deposited with substrate bias is enhanced relative to unbiased a-Si by films. The enhanced crystallization for substrate biased a-Si films are attributed to ion enhanced nucleation of crystallites during sputter deposition which subsequently grow during the postdeposition anneal. Conversely films sputter deposited without substrate bias have more intrinsic defects and residual oxygen which enhance nucleation and retard growth, respectively, and lead to a large number of small crystallites.

Jun, Seung-Ik; Rack, Philip D.; McKnight, Timothy E.; Melechko, Anatoli V.; Simpson, Michael L. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996-2200 (United States); Molecular Scale Engineering and Nanoscale Technologies Research Group, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2006-07-10T23:59:59.000Z

70

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

SciTech Connect (OSTI)

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

71

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

SciTech Connect (OSTI)

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

72

Recrystallization of amorphous silicon deposited on ultra thin microcrystalline silicon layers  

SciTech Connect (OSTI)

This study reports on a method to reduce the thermal crystallization time and temperature of amorphous silicon films by initially depositing an ultra thin {micro}c-Si:H seed layer. After rapid thermal annealing (RTA), films were characterized by means of Raman spectroscopy, x-ray diffraction, reflection high energy electron diffraction, atomic force microscopy, and dark and photocurrent. The results show that the microcrystalline particles in the seed layer act as nucleation centers, promoting crystallization of a-Si:H at lower temperatures and at shorter times, compared to a-Si:H films deposited without any seed layer. Additionally, it was found that the seed layer affects the orientation of the crystallized films. The dark current increases abruptly over 4 orders of magnitude in the first 15 second anneal, then decreases as the time increases, and tends to saturate. The photocurrent has an opposite behavior. These transport results can be understood in terms of a change in defect density and band gap shrinkage.

Wang, F.; Wolfe, D.; Lucovsky, G.

1997-07-01T23:59:59.000Z

73

E-Print Network 3.0 - amorphous silicon germanium Sample Search...  

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

6 September 2007; published online 17 October 2007 Amorphous silicon... -fiber optoelectronics.5,6 We have shown that crystalline silicon and ... Source: Gopalan, Venkatraman -...

74

E-Print Network 3.0 - amorphous-silicon-based solar cell Sample...  

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

Vol. 609 2000 Materials Research Society Preparation of Microcrystalline Silicon Based Solar Cells at High i-layer Summary: light exposure as do the amorphous silicon-based...

75

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

76

Determination of hydrogen density of states in amorphous silicon using fractional evolution experiments  

SciTech Connect (OSTI)

Hydrogen plays an important role in the electronic behavior, structure and stability of amorphous silicon films. Therefore, determination of the hydrogen density of states (DOS) and correlation of the hydrogen DOS with the electronic film properties are important research goals. The authors have developed a novel method for determination of hydrogen DOS in silicon films, based on fractional evolution experiments. Fractional evolution experiments are performed by subjecting a silicon film to a series of linear, alternating heating and cooling ramps, while monitoring the hydrogen evolution rate. The fractional evolution data can be analyzed using two complementary methods, the fixed frequency factor approach and Arrhenius analysis. Using a rigorous, mean-field evolution model, they demonstrate the applicability of the two approaches to obtaining the hydrogen DOS in silicon films. They further validate both methods by analyzing experimental fractional evolution data for an amorphous silicon carbide film. Both types of analysis yield a similar double peaked density of states for the a-Si:C:H:D film.

Franz, A.J.; Jackson, W.B.; Gland, J.L.

1997-07-01T23:59:59.000Z

77

Influence of deposition conditions on the 1/f noise in hydrogenated amorphous silicon  

SciTech Connect (OSTI)

The electronic properties of a series of n-type doped hydrogenated amorphous silicon (a-Si:H) films grown with deposition rates ranging from 2 {angstrom}/s to 33 {angstrom}/s have been studied. Infrared absorption spectroscopy shows an increase in Si-H{sub 2} content with deposition rate, concurrent with a decreasing conductivity, increasing thermal equilibration relaxation time, and increasing disorder at the mobility edge as measured by the difference in thermopower and dark conductivity activation energies. The current 1/f noise properties become highly nonstationary, with increased variability and inapplicability of statistical analysis as the deposition rate increases.

West, P.W.; Quicker, D.; Dyalsingh, H.M.; Kakalios, J.

1997-07-01T23:59:59.000Z

78

Thermal rectification at silicon-amorphous polyethylene interface Ming Hu,1,a  

E-Print Network [OSTI]

Thermal rectification at silicon-amorphous polyethylene interface Ming Hu,1,a Pawel Keblinski,1,b heat currents. We estimate that in the limit of large heat currents, the silicon-amorphous polyethylene by amorphous polymer polyethylene PE and silicon crystal. We will also show that the mecha- nism governing

Li, Baowen

79

Radial distribution functions of amorphous silicon  

Science Journals Connector (OSTI)

Substantial changes in the radial distribution function of amorphous Si films have been observed in neutron-diffraction studies. The spectra indicate changes in short-range order associated with an ?11% modification in the bond-angle distribution width. The results allow the first direct comparison of structural and vibrational Raman probes of variations in local order in thin-film amorphous solids. Good agreement is obtained between the measured bond-angle variation and that based on Raman estimates.

J. Fortner and J. S. Lannin

1989-03-15T23:59:59.000Z

80

Cellules solaires : quelques aspects des structures Schottky base de silicium amorphe hydrogn  

E-Print Network [OSTI]

obtenir des rendements suffisants (~ 10 %) pour une utilisation industrielle. A côté de couples CU2S-CdS hydrogenated amorphous silicon, highly doped hydrogenated amorphous silicon n+ a-Si:H and various metals. We

Paris-Sud XI, Université de

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

Amorphous Silicon as Semiconductor Material for High Resolution LAPS  

E-Print Network [OSTI]

-08 3.E -08 0 200 400 600 800 displacem ent/µµµµm current/A 1000 2000 3000 4000 1000 2000 3000 4000-substrate Amorphous silicon -4 -2 0 2 4 0,2 0,4 0,6 0,8 1,0 photocurrenta.u. gate voltage/V 600µm x 600µm area scan

Moritz, Werner

82

Conducting polymer and hydrogenated amorphous silicon hybrid solar cells  

E-Print Network [OSTI]

November 2005 An organic-inorganic hybrid solar cell with a p-i-n stack structure has been investigated for their potential in electronic devices such as organic light emitting diodes OLEDs , solar cells, photode- tectorsConducting polymer and hydrogenated amorphous silicon hybrid solar cells Evan L. Williams

Schiff, Eric A.

83

Charge-Density Variation in a Model of Amorphous Silicon  

Science Journals Connector (OSTI)

A population analysis of the one-electron eigenfunctions of random-network models of amorphous silicon shows fluctuations of the net atomic charge of about 0.2 electron units rms. The majority of the charge is calculable from a linear function of the deviations of first-neighbor distance and of the interbond angle from their values in the crystal.

Lester Guttman, W. Y. Ching, and Jagannath Rath

1980-06-09T23:59:59.000Z

84

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

SciTech Connect (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

85

Amorphous Silicon-Carbon Nanostructure Photovoltaic Devices  

E-Print Network [OSTI]

film is deposited over the window. . . . . . . . . . . . . . . . . . . . . . . . .A carbon film is deposited over the window. Figure 4.11:films and the silicon is unknown. However, changes in geometry such as varying the window

Schriver, Maria Christine

2012-01-01T23:59:59.000Z

86

High-Mobility Thin-Film Transistor Fabricated Using Hydrogenated Amorphous Silicon Deposited by Discharge of Disilane  

Science Journals Connector (OSTI)

Plasma-enhanced chemical vapor deposition of hydrogenated amorphous silicon (a-Si:H) film was investigated with emphasis on the effect of disilane flow rate. A coplanar thin-film transistor (TFT) was fabricated using this a-Si:H film. Silicon-hydrogen bond content in the a-Si:H film was measured by infrared absorption spectroscopy. With decrease in the disilane flow rate from 3.0 cm3/min to 1.5 cm3/min, the maximum field-effect electron mobility ( FE) of the TFT which depends on the gate voltage increased from 3.3 cm2/( Vs) to 4.9 cm2/( Vs), accompanied by a reduction in the silicon-hydrogen bond content. There was a negative correlation between FE and the silicon-hydrogen bond content in the a-Si:H film. The improvement mechanism of FE was discussed in terms of the chemical structure of the a-Si:H film.

Shigeichi Yamamoto; Junji Nakamura; Masatoshi Migitaka

1996-01-01T23:59:59.000Z

87

Optically induced conductivity changes in amorphous silicon: A historical perspective  

SciTech Connect (OSTI)

A historical perspective of the discovery of optically induced changes in amorphous silicon is presented in this paper from my personal point of view. It includes the story of how Chris Wronski and the author discovered the effect, the key elements in the R and D environment that lead to the quick realization that the effect was reversible and reproducible, how the research environment supported the rapid publication of their first paper, and a brief look at the effect from today's perspective.

Staebler, D.L.

1997-07-01T23:59:59.000Z

88

Systematic investigation of picosecond photoinduced absorption in hydrogenated amorphous silicon  

Science Journals Connector (OSTI)

A systematic study of the dependence of picosecond photoinduced absorption (PA) and transmission in hydrogenated amorphous silicon on sample thickness, doping concentration, and excitation intensity has been undertaken. Investigations demonstrated that the picosecond PA decays are not caused by recombination at the sample surface nor by deep trapping. The decays are consistent with thermalization within the band tails and doping-induced band-tail states.

W. B. Jackson; C. Doland; C. C. Tsai

1986-08-15T23:59:59.000Z

89

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

SciTech Connect (OSTI)

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

Melnikov, A. [Center for Advanced Diffusion-Wave Technologies (CADIFT), Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8 (Canada); Mandelis, A. [Center for Advanced Diffusion-Wave Technologies (CADIFT), Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8 (Canada); Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3G4 (Canada); Halliop, B.; Kherani, N. P. [Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3G4 (Canada)

2013-12-28T23:59:59.000Z

90

Simple method for preparing hydrogenated amorphous silicon films by chemical vapor deposition at atmospheric pressure  

SciTech Connect (OSTI)

An inexpensive one-step method is presented for fabricating hydrogenated amorphous silicon (a-Si:H) films with good photovoltaic properties using chemical vapor deposition (CVD) from a mixture of silane, disilane, trisilane, and higher polysilanes in hydrogen at one atmosphere total pressure. The gas mixture is generated by the action of dilute acid on magnesium silicide and used immediately in the CVD process. Thus, elaborate techniques for handling, transporting or storing the pyrophoric polysilanes are avoided. In addition, the method requires no expensive vacuum or electrical equipment. The conditions necessary for high (approx. =10%) hydrogen incorporation and very high deposition rates (50-100 A/sec) are explained. Experimental parameters are explained and properties as a function of these parameters are shown. The measurements include hydrogen content, optical, electrical and photovoltaic properties of the a-Si:H films. A chemical kinetic model is presented for this and other silane and polysilane CVD systems between about 400 and 600/sup 0/C. Both homogeneous and heterogeneous reactions are considered. The model is derived from homogeneous gas-phase silane and polysilane chemistry and predicts, in agreement with our experiments, that the homogeneous gas-phase chemistry determines the a-Si:H film growth rate under a variety of conditions. The model is sufficiently predictive to be useful in determining appropriate experimental conditions. Stable solar cells are proposed for a-Si:H and fluorine doped tin oxide which can be produced by CVD at very high deposition rates. The unstable a-Si:H/tin oxide interface is eliminated by a very thin layer of titanium nitride and oxide between the a-Si:H and tin oxide.

Ellis, F.B. Jr.

1983-01-01T23:59:59.000Z

91

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

DOE Patents [OSTI]

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

Madan, A.

1984-12-10T23:59:59.000Z

92

E-Print Network 3.0 - amorphous-silicon-based thin-film photovoltaic...  

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

CELLS... . 1. Transmittance modulation spectrum TT for an amorphous silicon-based pin solar cell prepared... . ACKNOWLEDGMENTS This research has been supported through the ......

93

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

DOE Patents [OSTI]

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

Yacobi, B.G.

1985-03-18T23:59:59.000Z

94

E-Print Network 3.0 - amorphous silicon photovoltaic Sample Search...  

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

results for: amorphous silicon photovoltaic Page: << < 1 2 3 4 5 > >> 1 Institute of Energy Conversion University of Delaware Summary: photovoltaics on flexible substrates....

95

E-Print Network 3.0 - amorphous silicon modules Sample Search...  

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

search results for: amorphous silicon modules Page: << < 1 2 3 4 5 > >> 1 Institute of Energy Conversion University of Delaware Summary: modules. Consulted for a research...

96

E-Print Network 3.0 - amorphous-silicon solar cells Sample Search...  

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

results for: amorphous-silicon solar cells Page: << < 1 2 3 4 5 > >> 1 Institute of Energy Conversion University of Delaware Summary: modules. Consulted for a research...

97

E-Print Network 3.0 - amorphous silicon flat-panel Sample Search...  

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

with the low cost of amorphous and polycrystalline silicon films on non... , such as solar cells and flat-panel displays, our ACSi technology promises to fundamentally...

98

Calorimetry of dehydrogenation and dangling-bond recombination in several hydrogenated amorphous silicon materials  

Science Journals Connector (OSTI)

Differential scanning calorimetry (DSC) was used to study the dehydrogenation processes that take place in three hydrogenated amorphous silicon materials: nanoparticles, polymorphous silicon, and conventional device-quality amorphous silicon. Comparison of DSC thermograms with evolved gas analysis (EGA) has led to the identification of four dehydrogenation processes arising from polymeric chains (A), SiH groups at the surfaces of internal voids (A?), SiH groups at interfaces (B), and in the bulk (C). All of them are slightly exothermic with enthalpies below 50meV?(H atoms), indicating that, after dissociation of any SiH group, most dangling bonds recombine. The kinetics of the three low-temperature processes [with DSC peak temperatures at around 320 (A), 360 (A?), and 430C (B)] exhibit a kinetic-compensation effect characterized by a linear relationship between the activation entropy and enthalpy, which constitutes their signature. Their Si?H bond-dissociation energies have been determined to be E(Si?H)0=3.14 (A), 3.19 (A?), and 3.28eV (B). In these cases it was possible to extract the formation energy E(DB) of the dangling bonds that recombine after Si?H bond breaking [0.97 (A), 1.05 (A?), and 1.12 (B)]. It is concluded that E(DB) increases with the degree of confinement and that E(DB)>1.10eV for the isolated dangling bond in the bulk. After Si?H dissociation and for the low-temperature processes, hydrogen is transported in molecular form and a low relaxation of the silicon network is promoted. This is in contrast to the high-temperature process for which the diffusion of H in atomic form induces a substantial lattice relaxation that, for the conventional amorphous sample, releases energy of around 600meV per H atom. It is argued that the density of sites in the Si network for H trapping diminishes during atomic diffusion.

P. Roura, J. Farjas, Chandana Rath, J. Serra-Miralles, E. Bertran, and P. Roca i Cabarrocas

2006-02-13T23:59:59.000Z

99

Thermopower and conductivity activation energies in hydrogenated amorphous silicon  

SciTech Connect (OSTI)

The long range fluctuation model has been widely used to account for the difference in activation energies seen experimentally in dark conductivity and thermopower measurements in hydrogenated amorphous silicon. The authors report on a test of this model using measurements of the conductivity and thermoelectric effects carried out in both open and short circuit configurations. While the thermopower activation energy is less than that of the dark conductivity, the short circuit Seebeck conductivity is found to be nearly identical to the dark conductivity in both activation energy and magnitude, consistent with the long range fluctuation model.

Dyalsingh, H.M.; Kakalios, J. [Univ. of Minnesota, Minneapolis, MN (United States). School of Physics and Astronomy

1996-12-31T23:59:59.000Z

100

Chemical vapor deposition of boron-doped hydrogenated amorphous silicon  

SciTech Connect (OSTI)

Deposition conditions and film properties for a variety of boron-doped hydrogenated amorphous silicon films and silicon-carbon films produced by chemical vapor deposition (CVD) are discussed. Deposition gases include monosilane, disilane, trisilane, and acetylene. Two types of optically wide band-gap p layers are obtained. One of these window p layers (without carbon) has been extensively tested in photovoltaic devices. Remarkably, this p layer can be deposited between about 200 to 300 /sup 0/C. A typical open circuit voltage in an all CVD p-i-n device is 0.70--0.72 V, and in a hybrid device where the i and n layers are deposited by glow discharge, 0.8--0.83 V.

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

1985-07-15T23:59:59.000Z

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.


101

LASER TRANSFER DOPING USING AMORPHOUS SILICON Rafel Ferr (Correspondence author)1  

E-Print Network [OSTI]

LASER TRANSFER DOPING USING AMORPHOUS SILICON Rafel Ferré (Correspondence author)1 , Ralf Gogolin1@isfh.de ABSTRACT: We demonstrate and characterize "Laser Transfer Doping" (LTD) for producing locally doped regions. For this purpose we use nanosecond pulsed laser for transferring phosphorus doped amorphous silicon from a carrier

102

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

103

Amorphous silicon-carbon alloys and amorphous carbon from direct methane and ethylene activation by ECR  

SciTech Connect (OSTI)

Hydrogenated amorphous silicon-carbon alloys are prepared using electron-cyclotron resonance (ECR) plasma-enhanced chemical vapor deposition. Hydrogen is introduced into the source resonance cavity as an excitation gas. Silane is introduced in the main chamber in the vicinity of the plasma stream, whereas the carbon source gases, methane or ethylene, are introduced either with the silane or with the hydrogen as excitation gases. The effect of the type of carbon-source gas, excitation gas mixture and silane-to-carbon source gas flow ratio on the deposition rate, bandgap, subgap density of states, spin density and hydrogen evolution are studied.

Conde, J.P.; Chu, V.; Giorgis, F.; Pirri, C.F.; Arekat, S.

1997-07-01T23:59:59.000Z

104

Chemical vapor deposition of amorphous silicon films from disilane  

SciTech Connect (OSTI)

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

105

Improved amorphous silicon alloy solar cells for module fabrication  

SciTech Connect (OSTI)

An initial conversion efficiency of 13.5% has been obtained on a triple-junction triple-bandgap device fabricated in a large-area deposition reactor capable of producing one-square-foot modules. The intrinsic layer of the top cell is a wide bandgap amorphous silicon alloy. The middle and bottom cells employ high quality amorphous silicon-germanium alloy. The high efficiency of the triple-junction cell is attributed to the relative reduction of the optical loss in the top tunnel junction and the improvement in the quality of the middle and bottom component cells. Triple-junction devices with initial efficiency of 13.3% have shown saturation at 11.6% after light soaking. Modules of aperture area 909 cm{sup 2} have been fabricated using an assembly process similar to the one being currently used in their manufacturing line. The module design consists of one large-area, high-current monolithic multijunction device. The status of the small-area devices and modules is described.

Banerjee, A.; Yang, J.; Guha, S.

1997-07-01T23:59:59.000Z

106

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

107

ESR studies on hot-wire amorphous silicon  

SciTech Connect (OSTI)

The authors measure a series of hot-wire (HW) amorphous silicon films grown with hydrogen contents C{sub H} varying between 0.5--17 at.%. From constant photocurrent method (CPM) measurements and the steady-state photocarrier grating method (SSPG) they find good agreement with previous measurements on similar hot-wire films. Electron spin resonance measurements on the same samples, however, yield significantly higher spin densities than expected. A thickness series indicates a highly defective layer close to the substrate interface. They propose that this defective layer may be due to excessive out diffusion of hydrogen during growth at high temperatures, as seen by secondary ion mass spectroscopy. ESR measurements on light-degraded samples indicate an improved stability of samples with C{sub H} < 9 at.%.

Unold, T.; Mahan, A.H.

1997-07-01T23:59:59.000Z

108

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

SciTech Connect (OSTI)

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

Yang, Yang [The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Room GB254B, Toronto, Ontario M5S 3G4 (Canada)] [The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Room GB254B, Toronto, Ontario M5S 3G4 (Canada); OBrien, Paul G. [Department of Materials Science and Engineering, University of Toronto, 184 College Street, Room 140, Toronto, Ontario M5S 3E4 (Canada) [Department of Materials Science and Engineering, University of Toronto, 184 College Street, Room 140, Toronto, Ontario M5S 3E4 (Canada); Materials Chemistry Research Group, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6 (Canada); Ozin, Geoffrey A., E-mail: gozin@chem.utoronto.ca, E-mail: kherani@ecf.utoronto.ca [Materials Chemistry Research Group, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6 (Canada); Kherani, Nazir P., E-mail: gozin@chem.utoronto.ca, E-mail: kherani@ecf.utoronto.ca [The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Room GB254B, Toronto, Ontario M5S 3G4 (Canada); Department of Materials Science and Engineering, University of Toronto, 184 College Street, Room 140, Toronto, Ontario M5S 3E4 (Canada)

2013-11-25T23:59:59.000Z

109

Structural, optical, and spin properties of hydrogenated amorphous silicon?germanium alloys  

Science Journals Connector (OSTI)

We report on a detailed study of structural and electronic properties of hydrogenated amorphous silicon?germanium alloys deposited by rf glow discharge from SiH4 and GeH4 in a diode reactor. The chemical composition of the alloys is related to the deposition conditions with special emphasis on preferential incorporation of Ge into the solid phase and on the role of inert dilutant gases. Hydrogen bonding in the alloys is investigated with nuclear magnetic resonance and vibrational (Raman and infrared) spectroscopy. The optical properties of a?SiGe:H samples deposited under optimal conditions are analyzed with the help of subgap absorption measurements and band?tail luminescence for the entire range of alloy composi?tions. A large part of the article describes an investigation of the electron?spin?resonance response of undoped alloys. The spin density associated with dangling bond defects localized on Si and Ge atoms has been measured as a function of alloy composition for optimized material. In addition the dependence of the two defect densities on the detailed deposition conditions (rf power substrate temperature and dilution) has been determined in a systematic way for alloys deposited from a plasma with a fixed SiH4/GeH4ratio. The results of this study especially the preferential creation of Gedangling bonds are discussed in the context of our structural data. Furthermore spin resonance is employed to investigate the light?induced degradation (StaeblerWronski effect) of a?SiGe:H. Finally the changes of the spin?resonance spectra of a?Si0.7Ge0.3 :H upon substitutional doping with phosphorus and boron have been obtained experimentally and are used to construct a model for the electronic density of states in this material.

M. Stutzmann; R. A. Street; C. C. Tsai; J. B. Boyce; S. E. Ready

1989-01-01T23:59:59.000Z

110

Quantum confinement in single layer a-Si:H films  

SciTech Connect (OSTI)

Quantum confinement effects in the transmission spectrum of thin amorphous silicon, a-Si:H, films require a coherence length comparable to the film thickness, as well as good film homogeneity. After a careful investigation, the authors conclude that there is no quantum confinement in single layer a-Si:H films at room temperature.

Koehler, S.A.; Fritzsche, H. [Univ. of Chicago, IL (United States)

1996-12-31T23:59:59.000Z

111

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

SciTech Connect (OSTI)

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

Gerlach, D.; Wilks, R. G.; Wimmer, M.; Felix, R.; Gorgoi, M.; Lips, K.; Rech, B. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Wippler, D.; Mueck, A.; Meier, M.; Huepkes, J. [Institut fuer Energie- und Klimaforschung, Forschungszentrum Juelich GmbH, Wilhelm-Johnen-Strasse, D-52428 Juelich (Germany); Lozac'h, M.; Ueda, S.; Sumiya, M. [National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Yoshikawa, H. [Synchrotron X-ray Station at SPring-8, NIMS, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Kobayashi, K. [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kouto 1-1-1, SPring-8, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Baer, M. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Institut fuer Physik und Chemie, Brandenburgische Technische Universitaet Cottbus, Konrad-Wachsmann-Allee 1, D-03046 Cottbus (Germany)

2013-07-08T23:59:59.000Z

112

Amorphous Silicon: The other Silicon J.C. Sturm, Y. Huang, L. Han, T. Liu, *B. Hekmatshoar,  

E-Print Network [OSTI]

for cost reduction, and crystalline silicon- amorphous silicon interfaces for high performance solar cells for analog and high duty cycle applications, flexible substrates for products with new form factors, printing Fig. 2. Pixel circuits for (a) active matrix liquid crystal display and (b) active matrix organic

113

Optical losses in amorphous silicon solar cells due to back reflectors  

SciTech Connect (OSTI)

The authors have used a new numerical model and here present initial results on how texturing and backreflectors affect the maximum achievable short-circuit current densities in amorphous silicon solar cells.

Sopori, B.L.; Madjdpour, J.; Von Roedern, B.; Chen, W.; Hegedus, S.S.

1997-07-01T23:59:59.000Z

114

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

DOE Patents [OSTI]

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

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

1980-08-26T23:59:59.000Z

115

CO2 laser CVD of a-Si:H: in situ gas analysis and model calculations  

Science Journals Connector (OSTI)

and disilane Si2H6 induced by continuous wave CO2 laser irradiation has been investigated under the conditions of chemical vapor deposition (CVD) of amorphous hydrogenated silicon a-Si:H. At the very position of...

F. Falk; G. Mollekopf; H. Stafast

1998-11-01T23:59:59.000Z

116

Mass spectrometric studies of impurities in silane and their effects on the electronic properties of hydrogenated amorphous silicon  

SciTech Connect (OSTI)

The concentration of volatile impurities in silane (SiH/sub 4/) and disilane (Si/sub 2/H/sub 6/) used to prepare hydrogenated amorphous silicon (a-Si:H) thin films by glow-discharge deposition has been measured by modulated molecular beam mass spectrometry with a sensitivity of 1 ppm. From dark conductivity measurements on these films the location of the Fermi energy E/sub F/ was determined. The Fermi levels of a-Si:H films were progressively lower with increasing concentrations of chlorine-containing molecules (mostly HCl and SiH/sub 3/Cl) in the silane, indicating that these species can act as weak p-type dopants in a-Si:H. Oxygen-containing species (mostly SiH/sub 3/OSiH/sub 3/) were also detected in silane. It is clear from these results that large variations in electronic properties of glow discharge a-Si:H can be attributed to differences in purity of silane used in the deposition.

Corderman, R.R.; Vanier, P.E.

1983-07-01T23:59:59.000Z

117

Amorphization and reduction of thermal conductivity in porous silicon by irradiation with swift heavy ions  

SciTech Connect (OSTI)

In this article, we demonstrate that the thermal conductivity of nanostructured porous silicon is reduced by amorphization and also that this amorphous phase in porous silicon can be created by swift (high-energy) heavy ion irradiation. Porous silicon samples with 41%-75% porosity are irradiated with 110 MeV uranium ions at six different fluences. Structural characterisation by micro-Raman spectroscopy and SEM imaging show that swift heavy ion irradiation causes the creation of an amorphous phase in porous Si but without suppressing its porous structure. We demonstrate that the amorphization of porous silicon is caused by electronic-regime interactions, which is the first time such an effect is obtained in crystalline silicon with single-ion species. Furthermore, the impact on the thermal conductivity of porous silicon is studied by micro-Raman spectroscopy and scanning thermal microscopy. The creation of an amorphous phase in porous silicon leads to a reduction of its thermal conductivity, up to a factor of 3 compared to the non-irradiated sample. Therefore, this technique could be used to enhance the thermal insulation properties of porous Si. Finally, we show that this treatment can be combined with pre-oxidation at 300 Degree-Sign C, which is known to lower the thermal conductivity of porous Si, in order to obtain an even greater reduction.

Newby, Pascal J. [Institut des Nanotechnologies de Lyon, Universite de Lyon, INL-UMR5270, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Institut Interdisciplinaire d'Innovation Technologique (3IT), Universite de Sherbrooke, CNRS UMI-LN2, Sherbrooke, Quebec J1K0A5 (Canada); Canut, Bruno; Bluet, Jean-Marie; Lysenko, Vladimir [Institut des Nanotechnologies de Lyon, Universite de Lyon, INL-UMR5270, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Gomes, Severine [Centre de Thermique de Lyon, Universite de Lyon, CETHIL-UMR5008, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Isaiev, Mykola; Burbelo, Roman [Faculty of Physics, Taras Shevchenko National University of Kyiv, 64/13, Volodymyrs'ka St., Kyiv 01601 (Ukraine); Termentzidis, Konstantinos [Laboratoire LEMTA, Universite de Lorraine-CNRS UMR 7563, 54506 Vandoeuvre-les-Nancy cedex (France); Chantrenne, Patrice [Universite de Lyon, INSA de Lyon, MATEIS-UMR CNRS 5510, Villeurbanne 69621 (France); Frechette, Luc G. [Institut Interdisciplinaire d'Innovation Technologique (3IT), Universite de Sherbrooke, CNRS UMI-LN2, Sherbrooke, Quebec J1K0A5 (Canada)

2013-07-07T23:59:59.000Z

118

Research on stable, high-efficiency amorphous silicon multijunction modules  

SciTech Connect (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

119

Light harvesting by planar photonic crystal in solar cells: The case of amorphous silicon  

E-Print Network [OSTI]

Light harvesting by planar photonic crystal in solar cells: The case of amorphous silicon Guillaume on light management in silicon thin film solar cells, using photonic crystals (PhC) structures. We by means of optical simulations performed on realistic thin film solar cell stacks. Theoretically

Boyer, Edmond

120

The Characteristics of Polysilicon Oxide Grown on Amorphous Silicon Deposited from Disilane  

Science Journals Connector (OSTI)

The characteristics of polysilicon oxide (polyoxide) grown on amorphous silicon deposited from disilane as the silicon source are reported on. The rate of amorphous silicon deposition from disilane is comparable to that of polysilicon deposition from silane. Moreover, the obtained polyoxide has the desirable electrical characteristics of lower leakage current and higher breakdown field than those of polyoxide grown on polysilicon deposition from silane, urgently needed for nonvolatile memory application. At the same time, the grown polysilicon oxides have lower electron trapping rates and larger charge-to-breakdown (Q bd), both attributable to their smoother polyoxide/polysilicon-1 interface than those of polyoxides grown on polysilicon deposition from silane.

YeouMing Lin; TanFu Lei

1997-01-01T23:59:59.000Z

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.


121

Elasticity, strength, and toughness of single crystal silicon carbide, ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous  

E-Print Network [OSTI]

Elasticity, strength, and toughness of single crystal silicon carbide, ultrananocrystalline diamond carbide 3C-SiC , ultrananocrystalline diamond, and hydrogen-free tetrahedral amorphous carbon

Espinosa, Horacio D.

122

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

SciTech Connect (OSTI)

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

123

Stability of hydrogenated amorphous silicon deposited at high temperatures with a remote hydrogen plasma  

Science Journals Connector (OSTI)

It is demonstrated that the stability of hydrogenated amorphous silicon (a?Si:H) is improved by deposition under the combined conditions of high substrate temperature (e.g. T D =400?C) and high hydrogen dilution as are readily achieved in a remote hydrogen plasma reactor. In comparison with optimized films from conventional rfglow dischargedeposition (e.g. silane 230?C 2 W) undoped high T D films possess a lower midgap defect density the dark dc conductivity in n?type (phosphorus?doped) films displays higher equilibration temperatures and longer relaxation times at a given temperature with an activation energy of 1.0 eV and undoped high T D films have a lower saturated density of light?induced defects. It is proposed that the ability to achieve the improved stability is a consequence of two effects: (1) the use of hydrogen dilution during deposition to maintain the hydrogen concentration in the film near 10 at.?% even at 400?C and (2) the possibility that at high T D s the hydrogen is more stably incorporated in the random network and/or that the density of weak SiSi bonds is smaller.

N. M. Johnson; C. E. Nebel; P. V. Santos; W. B. Jackson; R. A. Street; K. S. Stevens; J. Walker

1991-01-01T23:59:59.000Z

124

Ga configurations in hydrogenated amorphous silicon as studied by x-ray photoemission spectroscopy  

Science Journals Connector (OSTI)

Samples of crystalline silicon and glow-discharge-deposited hydrogenated amorphous silicon were doped with gallium by low-energy (4-keV) ion implantation. X-ray photoemission spectroscopy was used to study the chemical-bonding states of the Ga. From Ga 3d core-level studies, we found that elementary interstitial, threefold-coordinated, and fourfold-coordinated Ga coexist in the ion-implanted and annealed amorphous silicon network. The percentage of activated threefold- and fourfold-coordinated Ga atoms is found to increase with increasing annealing temperature, prior to crystallization. The energy released by the amorphous silicon lattice upon annealing contributes to the activation of the gallium from the elementary state to the threefold- or fourfold-coordinated state. No evidence of Ga-H bond formation is found. The percentage of fourfold-coordinated Ga, which we call the doping efficiency, ranges from 5% to 10%, depending upon the thermal treatment.

Z. H. Lu; S. Poulin-Dandurand; E. Sacher; A. Yelon

1990-09-15T23:59:59.000Z

125

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

SciTech Connect (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

126

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

SciTech Connect (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

127

Studying the nanostructure of a-Si:h solar cell absorber layers using positrion annihilation and neutron reflectometry:.  

E-Print Network [OSTI]

??Hydrogenated Amorphous Silicon (a-Si:H) is a very promising solar cell material with a good potential to use in many applications, as it is cheap to (more)

Mannheim, A.

2013-01-01T23:59:59.000Z

128

Hydrogen dynamics and light-induced structural changes in hydrogenated amorphous silicon T. A. Abtew* and D. A. Drabold  

E-Print Network [OSTI]

Hydrogen dynamics and light-induced structural changes in hydrogenated amorphous silicon T. A first-principles methods to study the network dynamics of hydrogenated amorphous silicon, including the motion of hydrogen. In addition to studies of atomic dynamics in the electronic ground state, we also

Drabold, David

129

Experimental determination of the distribution of tail states of hydrogenated amorphous silicon: A transient photocurrent analysis  

SciTech Connect (OSTI)

Recent experimental developments have cast doubt on the validity of the common assumption that the distribution of tail states of hydrogenated amorphous silicon exhibits a single exponential functional form. The authors employ transient photocurrent decay measurements to determine this distribution of tail states. In their approach, however, they determine the distribution of tail states directly from the experimental data, without assuming, a priori, a specific functional form. It is found that these experimental results are consistent with other more recent experimental determinations of the distribution of tail states, suggesting the possibility of deviations from a single exponential distribution of tail states in hydrogenated amorphous silicon.

Webb, D.P.; Chan, F.Y.M.; Zou, X.C.; Chan, Y.C.; Lam, Y.W.; Lin, S.H.; O'Leary, S.K.; Lim, P.K.

1997-07-01T23:59:59.000Z

130

EELS measurements of boron concentration profiles in p-a-Si and nip a-Si solar cells Bas B. Van Aken a,  

E-Print Network [OSTI]

that the optimum efficiency in nip solar cells is obtained when the p-a-SiC band gap is slightly larger than efficiency nip solar cells based on amorphous (a- Si:H) and microcrystalline (c-Si:H) silicon thin films efficiency Si solar cells, it is very important to control and limit the diffusion of B and C atoms

Dunin-Borkowski, Rafal E.

131

Single-crystalline silicon lift-off films for metaloxidesemiconductor devices on arbitrary substrates  

E-Print Network [OSTI]

foils using plasma- enhanced chemical-vapor deposition CVD of hydrogen- passivated, amorphous silicon (a-Si:HGaAs/GaAs heterojunction bipolar transistors on silicon,10 and high electron mobility transistors on quartz and sapphire11

Ludwig-Maximilians-Universität, München

132

Multi-resonant silver nano-disk patterned thin film hydrogenated amorphous silicon solar cells for Staebler-Wronski effect compensation  

E-Print Network [OSTI]

We study polarization independent improved light trapping in commercial thin film hydrogenated amorphous silicon (a-Si:H) solar photovoltaic cells using a three-dimensional silver array of multi-resonant nano-disk structures embedded in a silicon nitride anti-reflection coating (ARC) to enhance optical absorption in the intrinsic layer (i-a-Si:H) for the visible spectrum for any polarization angle. Predicted total optical enhancement (OE) in absorption in the i-a-Si:H for AM-1.5 solar spectrum is 18.51% as compared to the reference, and producing a 19.65% improvement in short-circuit current density (JSC) over 11.7 mA/cm2 for a reference cell. The JSC in the nano-disk patterned solar cell (NDPSC) was found to be higher than the commercial reference structure for any incident angle. The NDPSC has a multi-resonant optical response for the visible spectrum and the associated mechanism for OE in i-a-Si:H layer is excitation of Fabry-Perot resonance facilitated by surface plasmon resonances. The detrimental Staebl...

Vora, Ankit; Pearce, Joshua M; Bergstrom, Paul L; Gney, Durdu

2014-01-01T23:59:59.000Z

133

Numerical simulation of the heat transfer in amorphous silicon nitride membrane-based microcalorimeters  

E-Print Network [OSTI]

Numerical simulation of the heat transfer in amorphous silicon nitride membrane July 2003 Numerical simulations of the two-dimensional 2D heat flow in a membrane-based microcalorimeter have been performed. The steady-state isotherms and time-dependent heat flow have been calculated

Hellman, Frances

134

Short Channel Amorphous-Silicon TFT's on High-Temperature Clear Plastic Substrates  

E-Print Network [OSTI]

Short Channel Amorphous-Silicon TFT's on High-Temperature Clear Plastic Substrates K. Long, H@princeton.edu To achieve light-weight flexible AMOLED displays on plastic substrates, the substratesmust be optically clear for plastic. High-temperature plastics such as polyimide (e.g. KaptonB E) have a glass transition temperature

135

Exciton splitting and carrier transport across the amorphous-silicon/ polymer solar cell interface  

E-Print Network [OSTI]

of bilayer hybrid solar cells to better understand the physics controlling organic-inorganic device of Physics. DOI: 10.1063/1.2408641 Hybrid organic-inorganic solar cells combine the pro- cessabilityExciton splitting and carrier transport across the amorphous-silicon/ polymer solar cell interface

McGehee, Michael

136

Optimization of the absorption efficiency of an amorphous-silicon thin-film tandem solar cell  

E-Print Network [OSTI]

Optimization of the absorption efficiency of an amorphous-silicon thin-film tandem solar cell-wave approach was used to compute the plane-wave absorptance of a thin-film tandem solar cell with a metallic­4]. In this context, a basic idea is to periodically texture the metallic back reflector of a thin-film solar cell

137

Plasma post-hydrogenation of hydrogenated amorphous silicon and germanium  

SciTech Connect (OSTI)

Incorporation and kinetics of hydrogen during plasma post-hydrogenation and thermal treatment are discussed for a-Si:H and a-Ge:H films. For material of low hydrogen content, the hydrogen surface concentration reached by plasma treatment equals the hydrogen concentration obtained by deposition at the same temperature and under similar plasma conditions. Enhancements of the hydrogen diffusion coefficient and of hydrogen solubility observed for plasma treatment at temperatures {le}400 C and {le}300 C for a-Si:H and a-Ge:H, respectively, are attributed to a plasma induced rise of the surface hydrogen chemical potential.

Beyer, W.; Zastrow, U. [Forschungszentrum Juelich (Germany). Inst. fuer Schicht- und Ionentechnik

1996-12-31T23:59:59.000Z

138

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

SciTech Connect (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

139

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  

SciTech Connect (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

140

Crystalline Silicon under Acoustic Cavitation: From Mechanoluminescence to Amorphization  

Science Journals Connector (OSTI)

The physicochemical behavior of crystalline silicon under acoustic cavitation is investigated in water sparged with argon at low temperature (10 and 20 C). Surprisingly, spectroscopic investigations reveal that argon (bubbling continuously through the ...

Matthieu Virot; Rachel Pflieger; Ekaterina V. Skorb; Johann Ravaux; Thomas Zemb; Helmuth Mhwald

2012-06-21T23:59:59.000Z

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.


141

Photoconductivity and density of states in microstructural amorphous silicon  

SciTech Connect (OSTI)

It has been reported in previous works that using of RF 55 kHz PECVD method allows to deposit microstructural inhomogeneous a-Si:H films at high deposition rate (10--20{angstrom}/c) and with high photoconductivity. The structural analysis with using of IR spectroscopy and atomic force microscopy (AFM) performed in this work have shown that these films possess a relatively regular microstructure consisting of grains with characteristic size of {approximately}300--500{angstrom}. The regular microstructure of investigated films differs from inhomogeneous a-Si:H with deteriorate electronic properties. At the same time the diffraction analysis didn't reveal the presence of microcrystals. Therefore, the authors denoted their films as microstructural a-Si:H films. In this work they performed the modeling of the photoconductivity of microstructural a-Si:H films to analyze the density-of-states (DOS) responsible for recombination kinetics. For this purpose different approaches to photoconductivity modeling have been used to simulate the experimentally measured temperature dependence of photoconductivity. The comparative analysis of results of these simulations and ESR measurements have shown that recombination in high photoconductive microstructural films is controlled by deep neutral states.

Budaguan, B.G.; Aivazov, A.A.; Radosel'sky, A.G.; Popov, A.A.

1997-07-01T23:59:59.000Z

142

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

SciTech Connect (OSTI)

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

Kistner, J.; Schubert, M. B. [Institute for Photovoltaics and Research Center SCoPE, University of Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart (Germany)

2013-12-07T23:59:59.000Z

143

Template structure at the silicon/amorphous-silicide interface  

SciTech Connect (OSTI)

Surface x-ray diffraction was used to monitor the reaction of Ni on Si(111) at room temperature. Intensity oscillations during deposition signify that a layerwise reaction occurs for the first 30 A of metal deposited, forming a silicide overlayer with stoichiometry Ni{sub 2}Si. Structural analysis of the interfacial layers detects an epitaxial and commensurate phase, Ni{sub 2}Si-{theta}, with long range order imposed by the substrate but with very large local atomic displacements. This epitaxial structure remains at the interface as amorphous silicide forms above it.

Bennett, P.A.; Lee, M.Y.; Yang, P. [Department of Physics and Astronomy, Arizona State University, Box 871504, Tempe, Arizona 85287-1504 (United States)] [Department of Physics and Astronomy, Arizona State University, Box 871504, Tempe, Arizona 85287-1504 (United States); Schuster, R.; Eng, P.J.; Robinson, I.K. [Physics Department, University of Illinois, Urbana, Illinois 61801 (United States)] [Physics Department, University of Illinois, Urbana, Illinois 61801 (United States)

1995-10-02T23:59:59.000Z

144

Polyaniline on crystalline silicon heterojunction solar cells Weining Wanga  

E-Print Network [OSTI]

-Si have long been of fundamental interest, and amorphous silicon a-Si:H /c-Si heterojunctions are now is about the current limit achieved with a-Si:H/c-Si heterojunctions. The largest VOC we ob- tained was 0Polyaniline on crystalline silicon heterojunction solar cells Weining Wanga and E. A. Schiff

Schiff, Eric A.

145

Amorphous-Silicon Thin-Film Transistors Using Chemical Vapor Deposition of Disilane  

Science Journals Connector (OSTI)

Amorphous silicon layers have been deposited by low pressure chemical vapour deposition at 450C using disilane as the only source gas. Simple inverted staggered thin-film transistors were made with thermal silicon dioxide as the gate insulator. Field-effect mobilities for electrons and holes were 1.4 cm2/V s and 0.1 cm2/V s, respectively. In order to obtain these high mobilities the transistor structures were carefully annealed in a hydrogen-radical rich ambient.

PaulA. Breddels; Hiroshi Kanoh; Osamu Sugiura; Masakiyo Matsumura

1990-01-01T23:59:59.000Z

146

Research Progress in the DOE/SERI Amorphous Silicon Research Project  

SciTech Connect (OSTI)

The Amorphous Silicon Research Project (ASRP), established at the Solar Energy Research Institute (SERI) in 1983, is responsible for all U.S. DOE government-supported research activities in the field of amorphous silicon photovoltaics. The objectives and research directions of the project have been established by a Five-Year Research Plan developed at SERI in cooperation with the Department of Energy in 1984. In order to accomplish project goals, research is performed by a combination of i) multi-year programs consisting of multi-disciplinary research teams based on strong government/industry partnerships and ii) basic research performed in university, government, and industrial laboratories. A summary of recent research progress in the ASRP program is presented.

Sabisky, E.; Wallace, W.; Stafford, B.; Sadlon, K.; Luft, W.

1985-04-01T23:59:59.000Z

147

A detailed analysis of gains and losses of a fully-integrated flat roof amorphous silicon photovoltaic plant  

Science Journals Connector (OSTI)

In 2003 a fully-integrated photovoltaic (PV) plant composed by amorphous silicon PV modules was installed on top of a flat roof in Lugano (Southern Switzerland) a site representative for most of continental Europe and continuously monitored since. This work follows a previous study which analyzed the first 2years of operation of the plant, ascribing most of the noticeable winter losses to reflection losses due the lower position of the sun in the sky. Other loss mechanisms were discussed only from a qualitative point of view. The energy production of this particular PV installation is in fact influenced by several combined phenomena such as StaeblerWronski, spectral variations, temperature and optical losses effects. The present work aims to widen the analysis by discerning between these partly competitive effects and attempts to give a quantitative description of the influence which each single phenomenon has on the energy performance of the PV plant. For this purpose, single PV modules similar to those of the plant (triple-junction a-Si) were subjected to several indoor and outdoor tests. By means of indoor characterization we found that reflection losses become significant for angles of incidence larger than 50. Repeated indoor and outdoor degradationrecovery cycles underlined the influence of annealing time and temperature on the recovery of the PV modules. In particular outdoor degradation tests showed that at our latitudes (46N) the influence of the StaeblerWronski effect on the output power of these devices is around 10% (5% around an annual average value). The influence of the spectral effects on the current of amorphous silicon modules was assessed by means of outdoor IV characterization: the short circuit current decreases linearly with AM value at a slope between 4% and 8% per AM-unit depending on the technology under investigation. Combining these three effects with the effect of temperature the authors are able to perform a simulation of gains and losses of the a-Si modules which well approximates the energy performance of the CPT-Solar plant over a whole year.

Lorenzo Fanni; Alessandro Virtuani; Domenico Chianese

2011-01-01T23:59:59.000Z

148

Growth of Hydrogenated Amorphous Silicon Films by ArF Excimer Laser Photodissociation of Disilane  

Science Journals Connector (OSTI)

Hydrogenated amorphous silicon films have been grown on glass substrates by photodissociation of disilane using a pulsed ArF excimer laser foe the first time. Electrical and optical properties of the films have been examined. It was found that the magnitude of the gap energy of laser CVD films is rather large as compared to that of films obtained by a conventional plasma CVD. Preliminary examinations to control the conductivity by impurity doping have also been performed.

Akihiko Yoshikawa; Shigeki Yamaga

1984-01-01T23:59:59.000Z

149

High electric field effects on the thermal generation in hydrogenated amorphous silicon  

SciTech Connect (OSTI)

The authors have studied the electric field dependence of the electron-hole thermal generation process in hydrogenated amorphous silicon. A model was developed which takes into account the Poole-Frenkel effect and the thermally assisted tunneling. In order to explain the experimental results it was necessary to consider a strong electron-lattice interaction describing the carrier tunneling mechanism. Deep defects relaxation is also discussed.

Ilie, A.; Equer, B.

1997-07-01T23:59:59.000Z

150

Fluctuating defect density probed with noise spectroscopy in hydrogenated amorphous silicon  

SciTech Connect (OSTI)

Resistance fluctuations have been studied in hydrogenated amorphous silicon in the temperature range between 300 K and 450 K. The primary noise source has a power spectrum of approximately 1/f and is ascribed to hydrogen motion. Hopping of weakly bound hydrogen is thermally activated at such low temperatures with an average activation energy of 0.85 eV. The attempt rate amounts to 7 {center_dot} 10{sup 12} s{sup {minus}1}.

Verleg, P.A.W.E.; Uca, O.; Dijkhuis, J.I.

1997-07-01T23:59:59.000Z

151

Transient photoconductivity studies of the light soaked state of hydrogenated amorphous silicon  

Science Journals Connector (OSTI)

Studies of transient photoconductivity show that the primary effect of light soaking in hydrogenated amorphous silicon is to introduce dangling bonds of bulk density 101 6101 7 cm? 3. Light soaking reduces the ?? product of both electrons and holes to values which are quantitatively related to the observed increase in the dangling bondelectron spin resonance(ESR) spin density. In addition no change in the carrier drift mobilities is detected after light soaking.

R. A. Street

1983-01-01T23:59:59.000Z

152

Thermally?induced instabilities and the Staebler?Wronski effect in doped amorphous silicon  

Science Journals Connector (OSTI)

The quenched?in excess conductivity which results from the thermal equilibrium of the defect structure in doped hydrogenated amorphous silicon is compared to the Staebler?Wronski effect. Exposure to light or cooling below the equlibration temperature induces a metastable state described by the thermal equlibrium model. The time dependence of the relaxation of these metastable states is interpreted in terms of the hydrogen glass model.

J. Kakalios; R. A. Street

1987-01-01T23:59:59.000Z

153

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

SciTech Connect (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

154

Asymmetric electrical properties of fork a-Si:H thin-film transistor and its application to flat panel displays  

E-Print Network [OSTI]

of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, Michigan 48109, USA 2 LG-effect hydrogen- ated amorphous silicon a-Si:H solar cells to enhance out- put power.6 In an a-Si:H TFT, one pair

Kanicki, Jerzy

155

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

SciTech Connect (OSTI)

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

156

Photoluminescence properties and crystallization of silicon quantum dots in hydrogenated amorphous Si-rich silicon carbide films  

SciTech Connect (OSTI)

Silicon quantum dots (QDs) embedded in hydrogenated amorphous Si-rich silicon carbide (?-SiC:H) thin films were realized by plasma-enhanced chemical vapor deposition process and post-annealing. Fluorescence spectroscopy was used to characterize the room-temperature photoluminescence properties. X-ray photoelectron spectroscopy was used to analyze the element compositions and bonding configurations. Ultraviolet visible spectroscopy, Raman scattering, and high-resolution transmission electron microscopy were used to display the microstructural properties. Photoluminescence measurements reveal that there are six emission sub-bands, which behave in different ways. The peak wavelengths of sub-bands P1, P2, P3, and P6 are pinned at about 425.0, 437.3, 465.0, and 591.0?nm, respectively. Other two sub-bands, P4 is red-shifted from 494.6 to 512.4?nm and P5 from 570.2 to 587.8?nm with temperature increasing from 600 to 900?C. But then are both blue-shifted, P4 to 500.2?nm and P5 to 573.8?nm from 900 to 1200?C. The X-ray photoelectron spectroscopy analysis shows that the samples are in Si-rich nature, Si-O and Si-N bonds consumed some silicon atoms. The structure characterization displays that a separation between silicon phase and SiC phase happened; amorphous and crystalline silicon QDs synthesized with increasing the annealing temperature. P1, P2, P3, and P6 sub-bands are explained in terms of defect-related emission, while P4 and P5 sub-bands are explained in terms of quantum confinement effect. A correlation between the peak wavelength shift, as well as the integral intensity of the spectrum and crystallization of silicon QDs is supposed. These results help clarify the probable luminescence mechanisms and provide the possibility to optimize the optical properties of silicon QDs in Si-rich ?-SiC: H materials.

Wen, Guozhi [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); School of Electronic and Electrical Engineering, Wuhan Polytechnic University, Wuhan, Hubei 430023 (China); Zeng, Xiangbin, E-mail: eexbzeng@mail.hust.edu.cn; Wen, Xixin; Liao, Wugang [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2014-04-28T23:59:59.000Z

157

Growth-front roughening in amorphous silicon films by sputtering T. Karabacak,* Y.-P. Zhao, G.-C. Wang, and T.-M. Lu  

E-Print Network [OSTI]

Growth-front roughening in amorphous silicon films by sputtering T. Karabacak,* Y.-P. Zhao, G industry and is a material of special interest. The dy- namic roughening of silicon thin films grown

Wang, Gwo-Ching

158

From: Amorphous & Microcrystalline Silicon Technology, edited by S. Wagner, M. Hack, E. A. Schiff, R. Schropp, and I. Shimizu (Materials Research Society Symposium Proceedings, Vol.  

E-Print Network [OSTI]

From: Amorphous & Microcrystalline Silicon Technology, edited by S. Wagner, M. Hack, E. A. Schiff & Microcrystalline Silicon Technology, edited by S. Wagner, M. Hack, E. A. Schiff, R. Schropp, and I. Shimizu

Schiff, Eric A.

159

Nitrogen Diffusion in Amorphous Silicon Nitride Isotope Multilayers Probed by Neutron Reflectometry  

Science Journals Connector (OSTI)

Amorphous silicon nitride is a model system for a covalently bound amorphous solid with a low atomic mobility where reasonable values of self-diffusivities are still lacking. We used neutron reflectometry on isotope enriched Si3?N414/Si3?N415 multilayers to determine nitrogen self-diffusivities ranging from 10-24 to 10-21??m2/s between 950 and 1250?C. Time dependent diffusivities observed at 1150?C indicate the presence of structural relaxation. For long annealing times (relaxed state) the diffusivities follow an Arrhenius law with an activation enthalpy of (3.60.4)??eV. The results are indicative of a direct diffusion mechanism without the involvement of thermal point defects.

H. Schmidt; M. Gupta; M. Bruns

2006-02-07T23:59:59.000Z

160

Nitrogen Diffusion in Amorphous Silicon Nitride Isotope Multilayers Probed by Neutron Reflectometry  

SciTech Connect (OSTI)

Amorphous silicon nitride is a model system for a covalently bound amorphous solid with a low atomic mobility where reasonable values of self-diffusivities are still lacking. We used neutron reflectometry on isotope enriched Si{sub 3} {sup 14}N{sub 4}/Si{sub 3} {sup 15}N{sub 4} multilayers to determine nitrogen self-diffusivities ranging from 10{sup -24} to 10{sup -21} m{sup 2}/s between 950 and 1250 deg. C. Time dependent diffusivities observed at 1150 deg. C indicate the presence of structural relaxation. For long annealing times (relaxed state) the diffusivities follow an Arrhenius law with an activation enthalpy of (3.6{+-}0.4) eV. The results are indicative of a direct diffusion mechanism without the involvement of thermal point defects.

Schmidt, H.; Gupta, M.; Bruns, M. [AG Thermochemie und Mikrokinetik, Fakultaet fuer Natur-und Materialwissenschaften, TU Clausthal, D-38678 Clausthal-Zellerfeld (Germany); Laboratory for Neutron Scattering, ETH Zuerich and PSI, Paul Scherrer Institute, Villigen, CH-5232 (Switzerland); Institut fuer Instrumentelle Analytik, Forschungszentrum Karlsruhe GmbH, D-76021 Karlsruhe (Germany)

2006-02-10T23:59:59.000Z

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.


161

Wide band-gap, fairly conductive p-type hydrogenated amorphous silicon carbide films prepared by direct photolysis; solar cell application  

SciTech Connect (OSTI)

Wide optical band-gap (2.0--2.3 eV) undoped and boron-doped hydrogenated amorphous silicon carbide (a-SiC:H) films have been prepared by both direct photo and rf glow discharge (GD plasma) decomposition of pure methylsilanes or acetylene and disilane gas mixtures. The photochemically prepared p-type films showed higher dark conductivities and lower activation energies. For an optical band gap of 2.0 eV a high conductivity of 7.0 x 10/sup -5/ (S cm/sup -1/) and a low activation energy of 0.33 eV have been measured. The first trial of these wide band-gap, fairly conductive films as a window layer in a p-i-n solar cell showed the high conversion efficiency of 9.46% under AM1 insolation.

Yamada, A.; Kenne, J.; Konagai, M.; Takahashi, K.

1985-02-01T23:59:59.000Z

162

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

163

NANO EXPRESS Open Access Characterization of silicon heterojunctions for  

E-Print Network [OSTI]

at the interface between p-type hydrogenated amorphous silicon (a-Si:H) and n-type crystalline silicon (c-Si) as well as at the interface between n-type a-Si:H and p-type c-Si. This is in good agreement with planar are related to the existence of a strong inversion layer of holes at the c-Si surface of (p) a-Si:H/(n) c

Paris-Sud XI, Université de

164

Effect of radio-frequency bias voltage on the optical and structural properties of hydrogenated amorphous silicon carbide  

SciTech Connect (OSTI)

Hydrogenated amorphous silicon carbide (a-Si{sub 1{minus}x}C{sub x}:H) films have been deposited using the electron cyclotron resonance chemical vapor deposition process under varying negative rf-bias voltage at the substrate. The optical and structural properties of these films are characterized using Rutherford backscattering spectroscopy, transmittance/reflectance spectrophotometry, photothermal deflection spectroscopy, Fourier transform infrared absorption, Raman scattering, and room temperature photoluminescence (PL). These films deposited using a gas mixture of silane, methane, and hydrogen at a constant gas flow ratio showed a slight increase in the carbon fraction x, but very obvious structural transformation, at increasing rf induced bias voltage from {minus}20 to {minus}120 V. Near stoichiometric a-Si{sub 1{minus}x}C{sub x}:H films with a carbon fraction x of almost 0.5 are achieved at low bias voltage range from {minus}20 to {minus}60 V. Visible PL with relatively low efficiency can be observed from such films at room temperature. For larger bias voltages from {minus}80 to {minus}120 V, slightly C-rich a-Si{sub 1{minus}x}C{sub x}:H films (x{gt}0.5) with larger optical gaps are obtained. These films have relatively higher PL efficiency, and the relative quantum efficiency was also found to depend strongly on the optical gap. Structurally, it was found that there is an increase in the hydrogen content and carbon sp{sup 2} bonding in the films at larger bias voltages. The latter leads to an increase in the disorder in the films. The linear relationship observed between the Urbach energy E{sub 0} and B factor in the Tauc equation suggests that the local defects related to microstructural disorder resulting from alloying with carbon dominate the overall defect structure of the films. Substrate biasing is noted to be crucial for the formation of Si{endash}C bonds, as deduced from the Raman scattering results. {copyright} 2001 American Institute of Physics.

Cui, J.; Rusli; Yoon, S. F.; Teo, E. J.; Yu, M. B.; Chew, K.; Ahn, J.; Zhang, Q.; Osipowicz, T.; Watt, F.

2001-06-01T23:59:59.000Z

165

Atomic Structure of Interface States in Silicon Heterojunction Solar Cells B. M. George,1  

E-Print Network [OSTI]

silicon (a-Si:H=c-Si) heterojunction solar cells. We find that (i) the interface exhibits microscopic identify the microscopic origin of the conduction band tail state in the a-Si:H layer, and (iv) present-efficiency solar cells, is formed at the a-Si: H=c-Si interface [8]. Here, similar to other crystalline- amorphous

Schmidt, Wolf Gero

166

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

SciTech Connect (OSTI)

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

Demiro?lu, D. [Department of Metallurgical and Materials Engineering, Istanbul Technical University, Ayaza?a 34469, Istanbul (Turkey); Tatar, B. [Faculty of Arts and Sciences, Department of Physics, Nam?k Kemal University, De?irmenalt?, Tekirda? (Turkey); Kazmanli, K.; Urgen, M. [Department of Metallurgical and Materials Engineering, Istanbul Technical University, Ayaza?a 34469, Istanbul (Turkey)

2013-12-16T23:59:59.000Z

167

Metal-induced nanocrystalline structures in Ni-containing amorphous silicon thin films  

SciTech Connect (OSTI)

The mechanisms of silicon nanocrystal structure formation in amorphous Si films have been studied for a relative Ni impurity content varying between 0.1 and 10 at. %, i.e., from a Ni doping range to the Si-Ni alloy phase. The films, deposited by the cosputtering technique at 200 deg. C, were submitted to isochronal (15 min) annealing cycles up to 800 deg. C. Four different substrates were used to deposit the studied films: crystalline (c-) quartz, c-Si, c-Ge, and glass. Both the two orders of magnitude impurity concentration range variation and the very short annealing times were selected on purpose to investigate the first steps of the mechanism leading to the appearance of crystal seeds. The conclusions of this work are the following: (a) Ni impurity induces the low-temperature crystallization of amorphous silicon; (b) the NiSi{sub 2} silicide phase mediates, at the surface or in the bulk of the film, the crystallization process; and (c) the onset of crystallization and the crystalline fraction of the samples at each temperature depend not only on the Ni impurity concentration, but also on the nature of the substrate.

Ferri, F. A.; Zanatta, A. R.; Chambouleyron, I. [Instituto de Fisica de Sao Carlos-USP, Sao Carlos 13560-250, Sao Paulo (Brazil); Instituto de Fisica Gleb Wataghin-UNICAMP, Campinas 13083-970, Sao Paulo (Brazil)

2006-11-01T23:59:59.000Z

168

In-situ monitoring of surface hydrogen on the a-SiGe:H films  

SciTech Connect (OSTI)

The bonded hydrogen on the growing surface of hydrogenated amorphous silicon germanium (a-SiGe:H) alloy films has been investigated by use of infrared reflection absorption spectroscopy (IR-RAS). When the alloy films are Si-rich, the surface hydrogen bonded to Si atoms is found to behave in a similar way to those on the hydrogenated amorphous silicon (a-Si:H) films. This means that the thermal desorption stability of surface Si hydride species is not significantly affected by the coexistence of a small amount (typically 20 at.%) of Ge. On the contrary, the desorption behavior of surface hydrogen depends on the alloy composition when the a-SiGe:H films are Ge-rich. A surface reaction scheme is provided in an attempt to explain this series of behavior in surface hydrogen on the a-SiGe:H films.

Toyoshima, Y.; Ganguly, G.; Ikeda, T.; Saitoh, K.; Kondo, M.; Matsuda, A.

1997-07-01T23:59:59.000Z

169

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  

SciTech Connect (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

170

Silicon heterojunction solar cell with passivated hole selective MoOx contact Corsin Battaglia,1,2  

E-Print Network [OSTI]

amorphous silicon layer (a-Si:H) as surface passivation layer.3,4 Carrier selectivity at the contacts is traditionally achieved by depos- iting a doped a-Si:H layer after passivation. With this approach record open coefficient combined with a high defect density, a-Si:H, even when only a few nanometers thin, leads to sig

Javey, Ali

171

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

SciTech Connect (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

172

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

SciTech Connect (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

173

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

SciTech Connect (OSTI)

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

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

2014-03-10T23:59:59.000Z

174

Thin Ni silicide formation by low temperature-induced metal atom reaction with ion implanted amorphous silicon  

SciTech Connect (OSTI)

We have extended our recent work on buried silicide formation by Ni diffusion into a buried amorphous silicon layer to the case where silicide formation is at lower temperatures on silicon substrates which have been preamorphized. The reaction of metal atoms from a 12 nm Ni film evaporated on top of a 65 nm thick surface amorphous layer formed by 35 keV Si{sup +} ion implantation has been investigated at temperature {le}400C. Rutherford Backscattering Spectrometry (RBS) with channeling, cross-sectional transmission electron microscopy (XTEM), x-ray diffraction and four-point-probe measurements were used to determine structure, interfacial morphology, composition and resistivity of the silicide films. It has been found that an increased rate of silicidation occurs for amorphous silicon with respect to crystalline areas permitting a selective control of the silicon area to be contacted during silicide growth. Vacuum furnace annealing at 360C for 8 hours followed by an additional step at 400C for one hour produces a continuos NiSi{sub 2} layer with a resistivity 44 {mu}{Omega} cm.

Erokhin, Yu.N.; Pramanick, S.; Hong, F.; Rozgonyi, G.A. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Materials Science and Engineering; Patnaik, B.K. [North Carolina State Univ., Raleigh, NC (United States)

1992-12-31T23:59:59.000Z

175

E-Print Network 3.0 - amorphous silicon research Sample Search...  

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

Silicon Silicon is the second most... distinct forms. The possibility of a phase transition between two liquid forms in silicon, ... Source: Goldberg, Bennett - Department of...

176

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

SciTech Connect (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

177

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

178

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

SciTech Connect (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

179

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

SciTech Connect (OSTI)

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

180

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

DOE Patents [OSTI]

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

Li, Yaun-Min (Langhorne, PA); Bennett, Murray S. (Langhorne, PA); Yang, Liyou (Plainsboro, NJ)

1999-08-24T23:59:59.000Z

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.


181

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

DOE Patents [OSTI]

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

Li, Yaun-Min (Langhorne, PA); Bennett, Murray S. (Langhorne, PA); Yang, Liyou (Plainsboro, NJ)

1997-07-08T23:59:59.000Z

182

Hydrogen density of states and defects densities in a-Si:H  

SciTech Connect (OSTI)

The properties of hydrogenated amorphous silicon (a-Si:H) and its devices depend fundamentally on the density of states (DOS) in the gap due to dangling bonds. It is generally believed that the density of dangling bonds is controlled by a chemical equilibrium with the weak Si-Si bonds which form the localized valence band tail states. Further details are given of a unified model of the hydrogen density of states and defect pool of a-Si:H. The model is compared to other defect models and extended to describe a-Si alloys and the creation of valence band tail states during growth.

Deane, S.C.; Powell, M.J. [Philips Research Labs., Redhill, Surrey (United Kingdom); Robertson, J. [Cambridge Univ. (United Kingdom). Engineering Dept.

1996-12-31T23:59:59.000Z

183

Electron spin resonance of ultrahigh vacuum evaporated amorphous silicon: In situ and ex situ studies  

Science Journals Connector (OSTI)

An in situ study of the electron spin resonance (ESR) of ultrahigh vacuum evaporated amorphous silicon is performed to define the characteristics of the signal as a function of preparation conditions. The influence of deposition rate, temperature of substrates, temperature of annealing, angle of incidence of the vapor beam, contamination by air exposure, and the presence of hydrogen during growth have been investigated. Porosity effects depending on thermal history and angle of incidence, which allow contamination, are observed by ESR. It is found that the spin density is mainly determined by the thermal history and varies only within a factor of about 3 when contamination effects are not involved. This is contrary to other results which we believe were obtained from contaminated specimens. Related variations of linewidth and saturation behavior are observed. Ex situ measurements of linewidth, saturation behavior, and ESR susceptibility are done as a function of temperature. The results of these measurements are discussed in terms of two extreme possibilities for spins: individual spins randomly distributed and clusters of spins. The question of a possible association of spins with voids is also discussed. The results are compatible with a model of individual spins randomly distributed. An approach to the relation between spins and conductivity is presented.

P. A. Thomas; M. H. Brodsky; D. Kaplan; D. Lepine

1978-10-01T23:59:59.000Z

184

Tight-binding study of the electronic structure of amorphous silicon  

Science Journals Connector (OSTI)

We have performed tight-binding calculations on a model of an amorphous silicon sample generated previously by a molecular-dynamics simulation employing the Stillinger-Weber potential. The sample consists of 588 atoms and contains a high density of floating-bond defects. Two tight-binding calculations are presented, one using the widely accepted Chadi parameters, which include only nearest-neighbor interactions, and the other using the parameters recently proposed by Allen, Broughton, and McMahan (ABM) [Phys. Rev. B 34, 859 (1986)] for a nonorthogonal basis set. Comparison of the densities of states shows similar behavior in the valence band, but the electron density near a defect is less localized with the ABM parameters. It is also found that the projected density of states on the fivefold-coordinated atoms is very close to that on the fourfold-coordinated atoms, while the projected density of states on the threefold-coordinated atoms is distinctly different and has more states in the gap.

James L. Mercer; Jr. and M. Y. Chou

1991-03-15T23:59:59.000Z

185

E-Print Network 3.0 - amorphous silicon oxynitride Sample Search...  

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

poly-silicon... and Insulators SiO2 Si3N4 Conductors Poly-Silicon (doped and undoped) Tungsten Copper 12;HarvardFabrication2... Single Crystal Silicon SiO2 deposition...

186

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

SciTech Connect (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

187

E-Print Network 3.0 - amorphous silicon carbide Sample Search...  

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

50, mai 1989 Summary: revetementdans le substrat. Abstract - Cuttingtools made of A1203+TiC, silicon nitride,carbide, and stabi- lized... with Tic, silicon nitride,...

188

Transition from Irradiation-Induced Amorphization to Crystallization...  

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

from Irradiation-Induced Amorphization to Crystallization in Nanocrystalline Silicon Carbide. Transition from Irradiation-Induced Amorphization to Crystallization in...

189

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

SciTech Connect (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

190

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

SciTech Connect (OSTI)

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

191

Enhanced quantum efficiency of amorphous silicon thin film solar cells with the inclusion of a rear-reflector thin film  

SciTech Connect (OSTI)

We investigated the growth mechanism of amorphous silicon thin films by implementing hot-wire chemical vapor deposition and fabricated thin film solar cell devices. The fabricated cells showed efficiencies of 7.5 and 8.6% for the samples without and with the rear-reflector decomposed by sputtering, respectively. The rear-reflector enhances the quantum efficiency in the infrared spectral region from 550 to 750?nm. The more stable quantum efficiency of the sample with the inclusion of a rear-reflector than the sample without the rear-reflector due to the bias effect is related to the enhancement of the short circuit current.

Park, Seungil [Department of Mechanical Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Energy Conversions Technology Center, Korea Institute of Industrial Technology, Cheonan 331-825 (Korea, Republic of); Yong Ji, Hyung; Jun Kim, Myeong; Hyeon Peck, Jong [Energy Conversions Technology Center, Korea Institute of Industrial Technology, Cheonan 331-825 (Korea, Republic of); Kim, Keunjoo, E-mail: kimk@chonbuk.ac.kr [Department of Mechanical Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

2014-02-17T23:59:59.000Z

192

Nanostructured silicon thin films deposited by PECVD in the presence of silicon nanoparticles  

SciTech Connect (OSTI)

Nanostructured silicon thin films have been deposited by plasma enhanced chemical vapor deposition at low substrate temperature (100 C) in the presence of silicon nanoparticles. The nanostructure of the films was revealed by transmission electron microscopy, Raman spectroscopy and X-ray diffraction, which showed ordered silicon domains (1--2 nm) embedded in an amorphous silicon matrix. These ordered domains are due to the particles created in the discharge that contribute to the film growth. One consequence of the incorporation of nanoparticles is the accelerated crystallization of the nanostructured silicon thin films when compared to standard a-Si:H, as shown by the electrical characterization during the annealing.

Viera, G.; Cabarrocas, P.R.; Hamma, S.; Sharma, S.N.; Costa, J.; Bertran, E.

1997-07-01T23:59:59.000Z

193

ITO, Si3N4 and ZnO: Al -- Simulation of Different Anti-reflection Coatings (ARC) for Thin Film a-Si:H Solar Cells  

Science Journals Connector (OSTI)

For thin film solar cells incorporating amorphous silicon (a-Si:H) as absorber materials, minimizing reflection from the top surface i.e. maximizing transmittance of the incoming light into the absorber for higher absorption plays an important role for ... Keywords: ARC, TCO, ITO, Si3N4, ZnO:Al, Solar cell

Kazi Islam; Aaesha Alnuaimi; Helmy Ally; Ammar Nayfeh

2013-11-01T23:59:59.000Z

194

E-Print Network 3.0 - amorphous silicon flat Sample Search Results  

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

Cells n Sensors n Flat Panels n IC Circuits... and low-performance, low-cost amorphous film solar cells. n Potential for high ... Source: Los Alamos National Laboratory,...

195

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

SciTech Connect (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

196

Advanced polycrystalline silicon thin film solar cells using high rate plasma enhanced chemical vapour deposited amorphous silicon on textured glass.  

E-Print Network [OSTI]

??Solid phase crystallized polycrystalline silicon (poly-Si) thin-film solar cell on glass is an emerging Photovoltaics (PV) technology combining the robustness of crystalline Si material with (more)

Jin, Guangyao

2010-01-01T23:59:59.000Z

197

Technology of Amorphous Silicon Thin Films for Solar Cells and Applications to Power Systems  

Science Journals Connector (OSTI)

Preliminary attempts have been made to grow non-hydrogenated a-Si films by evaporation in an ordinary vacuum system (ultimate pressure 10?6 Toor) fitted with a six-hearth electron gun and a substrate heater. This...

D. Girginoudi; A. Thanailakis; P. Abarian

1983-01-01T23:59:59.000Z

198

Real-time ESR observation during film growth of a-Si:H  

SciTech Connect (OSTI)

In-situ electron-spin-resonance (ESR) measurements of film growth of hydrogenated amorphous silicon (a-Si:H) using a remote hydrogen plasma technique have been performed. The Si dangling-bond signal in a-Si:H during and after deposition has been detected, in addition to the gas-phase ESR signals both of atomic hydrogen and photo-excited SiH{sub x} molecules. Dynamic changes of the Si dangling-bond signal intensity were observed when the deposition started and stopped, which has suggested the existence of a subsurface region with higher spin density than that in the bulk region.

Yamasaki, S.; Umeda, T.; Isoya, J.; Tanaka, K.

1997-07-01T23:59:59.000Z

199

E-Print Network 3.0 - amorphous silicon-based solar Sample Search...  

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

University of Toledo Collection: Renewable Energy 3 21st European Photovoltaic Solar Energy Conference (2006) DEFECT DENSITY IN SILICON HETEROJUNCTIONS Summary: voltage, V , and...

200

E-Print Network 3.0 - amorphous silicon nitride Sample Search...  

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

nitride, aluminium oxide, titanium nitride are promising materials for the high... of powder analysis made by the following processes: - Preparation of silicon nitride by...

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

High-rate deposition of hydrogenated amorphous silicon films and devices  

SciTech Connect (OSTI)

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

202

Arsenic redistribution after solid phase epitaxial regrowth of shallow pre-amorphized silicon layers  

SciTech Connect (OSTI)

The behavior of ultra shallow ion implants of arsenic in Si following solid phase epitaxial re-growth process is reported. A 16 nm amorphous layer was created by ion implantation of Si{sup +} at energy 5 keV and a dose 1 Multiplication-Sign 10{sup 15} at/cm{sup 2}. As ion were implanted at 2 keV using 3 different doses: 1 Multiplication-Sign 10{sup 14}, 5 Multiplication-Sign 10{sup 14} and 1 Multiplication-Sign 10{sup 15} at/cm{sup 2}. The resulting As distributions, confined in the amorphous layer, were thermally treated at 550 Degree-Sign C for 5-300 s in order to electrically activate dopant atoms. Crystal re-growth and As redistribution was investigated by secondary ion mass spectrometry and medium energy ion scattering. A growth rate depending on the As concentration was observed, the rate being slower for higher As content. Arsenic re-distribution to the surface and at the end-of-range defects was observed and a segregation model was developed. Finally, the substitutional fraction of As atoms was related to sheet resistance measurements revealing a higher fraction of electrically active dopant atoms in pre-amorphized samples compared to not pre-amorphized.

Demenev, E.; Giubertoni, D.; Gennaro, S.; Bersani, M.; Hourdakis, E.; Nassiopoulou, A. G.; Reading, M. A.; Berg, J. A. van den [CMM, Fondazione Bruno Kessler, Via Sommarive 18. 38123 Povo - Trento (Italy); NCSR Demokritos, IMEL, Terma Patriarchou Grigoriou, Aghia Paraskevi, Athens (Greece); Centre for Materials and Physics, University of Salford (United Kingdom)

2012-11-06T23:59:59.000Z

203

Thermal generation currents in hydrogenated amorphous silicon p?i?n structures  

Science Journals Connector (OSTI)

Dark conductivity in amorphous siliconp?i?n devices arising from thermal generation through bulk defect states is explored. The current decays slowly after a voltage is applied due to depletion of charge from the undoped layer and is voltage dependent due to a field?enhanced generation rate. Creation of metastable bulk defects by light soaking reversibly increases the current. The steady?state generation current is dervied from the measuredrelaxation time and depletion charge.

R. A. Street

1990-01-01T23:59:59.000Z

204

Electronic structure of twofold-coordinated atoms in silicon-based amorphous semiconductors  

Science Journals Connector (OSTI)

Electronic states of the twofold-coordinated N atom in a-SixNi1-x:H and twofold-coordinated P atom in P-doped a-Si:H have been calculated using the density-functional theory with a local-spin-density approximation. The calculated N14 hyperfine parameters agree fairly well with those observed in N-rich a-SixN1-x:H by electron-spin-resonance (ESR) experiments, confirming the ESR center to be a twofold-coordinated N atom. On the other hand, the calculated P31 hyperfine parameters are largely different from the observed values for the ESR center with a 250-G splitting in P-doped a-Si:H. Therefore the ESR center should not be identified as a twofold-coordinated P atom.

Nobuhiko Ishii and Tatsuo Shimizu

1991-12-15T23:59:59.000Z

205

E? Centers in Amorphous SiO2 Revisited: A New Look at an Old Problem  

Science Journals Connector (OSTI)

We present theoretical evidence that the paramagnetic E? defect centers in amorphous silicon dioxide ( a-SiO2) do not have the same microscopic structures as those well-defined in the corresponding crystalline counterparts such as ?-quartz. We then present alternative models of some paramagnetic defects that account for the underlying experimental features of the E?-center variants in a-SiO2. We suggest that our new model should take the place of the conventional defect model of a-SiO2.

T. Uchino; M. Takahashi; T. Yoko

2001-06-11T23:59:59.000Z

206

GaN-nanowire/amorphous-Si core-shell heterojunction diodes  

Science Journals Connector (OSTI)

We report the electrical characterization of gallium-nitride/amorphous-silicon ( n -type nanowire/ p -type shell) diodesfabricated by postgrowth silicon shell formation technique. The n -type (unintentionally doped) gallium-nitride (GaN)nanowires were aligned on prepatterned sapphire substrates using dielectrophoresis. The amorphous silicon ( a -Si ) shell was deposited using plasma enhanced chemical vapor deposition technique and doped using spin-on boron dopant. Using photolithography plasma etching and metal deposition complete p - n ( p -type a -Si shell on n -type GaNnanowire)heterojunctiondiodes were developed. These diodes had reliable electrical characteristics with 1 V forward turn-on voltage. These nanowire core-shell heterojunctiondiodes exhibited negative differential resistance which can be explained by phonon-assisted interband tunneling mechanism.

Abhishek Motayed; Albert V. Davydov

2008-01-01T23:59:59.000Z

207

Development of tandem amorphous/microcrystalline silicon thin-film large-area see-through color solar panels with reflective layer and 4-step laser scribing for building-integrated photovoltaic applications  

Science Journals Connector (OSTI)

In this work, tandem amorphous/microcrystalline silicon thin-film large-area see-through color solar modules were successfully designed and developed for building-integrated photovoltaic applications. Novel and key technologies of reflective layers and ...

Chin-Yi Tsai, Chin-Yao Tsai

2014-01-01T23:59:59.000Z

208

Laser photochemical growth of amorphous silicon at low temperatures and comparison with thermal chemical vapor deposition  

SciTech Connect (OSTI)

Pulsed ArF (193 nm) excimer laser radiation has been used to dissociate disilane (Si/sub 2/H/sub 6/, resulting in photochemically controlled deposition of amorphous Si thin films. A high stability HeNe (6328 A) laser was used for precise in situ monitoring of film deposition rates, under varying deposition conditions. A helium window purge nearly eliminated Si film deposition on the chamber windows. With the excimer laser beam parallel to the substrate, deposition of amorphous Si can be controlled entirely by the photon fluence (negligible background thermal growth) at temperatures from room temperature up to /approximately/400/degree/C. Reasonable photolytic deposition rate (>1 A/sec) are combined with 'digital' control of film thickness (/approx gt/0.02 A/laser pulse). Activation energies of 1.50 (+-0.1) eV and 0.09 (+-0.02) eV were found for pyrolytic and photolytic deposition, respectively. 15 refs., 3 figs.

Eres, D.; Lowndes, D.H.; Geohegan, D.B.; Mashburn, D.N.

1987-01-01T23:59:59.000Z

209

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

SciTech Connect (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

210

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

SciTech Connect (OSTI)

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

211

The freezing tendency towards 4-coordinated amorphous network causes increase in heat capacity of supercooled Stillinger-Weber silicon  

E-Print Network [OSTI]

The supercooled liquid silicon, modeled by Stillinger-Weber potential, shows anomalous increase in heat capacity $C_p$, with a maximum $C_p$ value close to 1060 K at zero pressure. We study equilibration and relaxation of the supercooled SW Si, in the temperature range of 1060 K--1070 K at zero pressure. We find that as the relaxation of the metastable supercooled liquid phase initiates, a straight line region (SLR) is formed in cumulative potential energy distributions. The configurational temperature corresponding to the SLR is close to 1060 K, which was earlier identified as the freezing temperature of 4-coordinated amorphous network. The SLR is found to be tangential to the distribution of the metastable liquid phase and thus influences the broadness of the distribution. As the bath temperature is reduced from 1070 K to 1060 K, the effective temperature approaches the bath temperature which results in broadening of the metastable phase distribution. This, in turn, causes an increase in overall fluctuations of potential energy and hence an increase of heat capacity. We also find that during initial stages of relaxation, 4-coordinated atoms form 6-membered rings with a chair--like structure and other structural units that indicate crystallization. Simultaneously a strong correlation is established between the number of chair-shaped 6-membered rings and the number of 4-coordinated atoms in the system. This shows that all properties related to 4-coordinated particles are highly correlated as the SLR is formed in potential energy distributions and this can be interpreted as a consequence of `freezing' of amorphous network formed by 4-coordinated particles.

Pankaj A. Apte; Nandlal Pingua; Arvind Kumar Gautam; Uday Kumar; Soohaeng Yoo Willow; Xiao Cheng Zeng; B. D. Kulkarni

2014-04-10T23:59:59.000Z

212

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

SciTech Connect (OSTI)

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

213

E-Print Network 3.0 - aspect ratio silicon Sample Search Results  

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

amorphous Si layer... into amorphous silicon with the formation of metastable amorphous metal silicide. Supersaturation... and decomposition of the metastable amorphous metal...

214

On the compensation mechanism of amorphous silicon films: Study of stability  

SciTech Connect (OSTI)

The authors investigated a-Si:H compensated materials deposited over a wide range of gas dopant concentrations, from 0.125 ppm up to 10{sup 3} ppm. They achieved compensation for different ratio in the gas phase of diborane and phosphine, depending on their concentration. As a relevant result, they found that at constant boron concentration compensation occurs by using two different values of phosphine flow. This behavior can be described by a change of formation mechanism involving active dopants, defects and boron-phosphorus complex, that occurs in a different way depending on the dopant concentrations. The two compensation regimes are evidenced also by a different behavior under light soaking. Furthermore they found that photocurrent evolution under illumination is determined by two concurrent mechanisms: activation of dopant species and increase of defect density.

Caputo, D.; De Cesare, G.; Palma, F.; Tucci, M.; Minarini, C.; Terzini, E.

1997-07-01T23:59:59.000Z

215

Si6H12/Polymer Inks for Electrospinning a-Si Nanowire Lithium Ion Battery Anodes  

SciTech Connect (OSTI)

Amorphous silicon nanowires 'a-SiNWs' have been prepared by electrospinning a liquid silane-based precursor. Cyclohexasilane 'Si6H12' was admixed with poly-methyl methacrylate (PMMA) in toluene giving an ink that was electrospun into the Si6H12/PPMA wires with diameters of 50-2000 nm. Raman spectroscopy revealed that thermal treatment at 350 C transforms this deposit into a-SiNWs. These materials were coated with a thin carbon layer and then tested as half-cells where a reasonable plateau in electrochemical cycling was observed after an initial capacity fade. Additionally, porous a-SiNWs were realized when the thermally decomposable binder polypropylene carbonate/polycyclohexene carbonate was used as the polymer carrier.

Schulz, Douglas L.; Hoey, Justin; Smith, Jeremiah; Elangovan, Arumugasamy; Wu, Xiangfa; Akhatov, Iskander; Payne, Scott; Moore, Jayma; Boudjouk, Philip; Pederson, Larry; Xiao, Jie; Zhang, Jiguang

2010-08-04T23:59:59.000Z

216

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

SciTech Connect (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

217

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

SciTech Connect (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

218

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

SciTech Connect (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

219

Synthesis and characterization of P-doped amorphous and nanocrystallin...  

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

characterization of P-doped amorphous and nanocrystalline Si. Synthesis and characterization of P-doped amorphous and nanocrystalline Si. Abstract: P-doped amorphous Si (a-Si) was...

220

Ambipolar silicon nanowire FETs with stenciled-deposited metal gate Davide Sacchetto  

E-Print Network [OSTI]

Ambipolar silicon nanowire FETs with stenciled-deposited metal gate Davide Sacchetto , Veronica Keywords: Schottky barrier Ambipolarity Si nanowire Stencil lithography FET Silicide a b s t r a c t We chemical vapor deposition (LPCVD) of amorphous Si (a-Si) and SiO2 layers as well as metal gate patterning

De Micheli, Giovanni

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

Optical absorption band at 5.8 eV associated with the E{sub {gamma}}{sup '} centers in amorphous silicon dioxide: Optical absorption and EPR measurements  

SciTech Connect (OSTI)

Line shape modifications induced by thermal treatment in the optical absorption and electron paramagnetic resonance (EPR) signals associated with the E{sub {gamma}}{sup '} center are experimentally investigated in various types of {gamma}-irradiated amorphous silicon dioxide (a-SiO{sub 2}). The g values of the EPR main resonance line of the E{sub {gamma}}{sup '} center show a shift correlated with the peak energy variation of the absorption band at about 5.8 eV associated with this defect. These spectroscopic changes are proposed to originate from structural modifications of the defect environment. The correlation is theoretically explained considering that the spin-orbit interaction couples the g-tensor's elements and the electronic energy level distribution of the defect. Our results suggest that the optical band at 5.8 eV is due to an intracenter electron promotion from the Si-O bonding states to the dangling bond of the O{identical_to}Si moiety.

Agnello, S.; Buscarino, G.; Gelardi, F. M.; Boscaino, R. [Department of Physical and Astronomical Sciences, University of Palermo, Via Archirafi 36, I-90123 Palermo (Italy)

2008-05-15T23:59:59.000Z

222

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

SciTech Connect (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

223

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

SciTech Connect (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

224

Adhesion measurement of zirconium nitride and amorphous silicon carbide coatings to nickel and titanium alloys  

Science Journals Connector (OSTI)

Polycrystalline ZrN and amorphous Si0.57C0.43 coatings were deposited by cathodic arc evaporation and by plasma-assisted chemical vapor deposition (PACVD) respectively on Incoloy 825 (Inc.825), Hastelloy C22 (Hast.C22) and Titanium Grade 12 (Ti.12) substrates. Scratch tests were employed to assess the critical load for interfacial failure and fracture mechanisms for the various coating systems. Critical loads, characterized by continuous delamination of the coating, occurred at 41.2N, 44.1N and 29.4N for ZrN deposited on Hast.C22, Inc.825 and Ti.12 respectively. Interfacial failure of the Si0.57C0.43-coated metallic substrates was dominated by brittle fracture of the Si0.57C0.43 coating. Critical loads of 2.9N, 3.9N and 6.8N were obtained for Si0.57C0.43 deposited on Inc.825, Hast.C22 and Ti.12 respectively. Work of adhesion values were calculated from two well-known models, namely the BullRickerby and Laugier models, and from a model that incorporates elasticplastic indentation. The ranking of the adhesion for the coatingmetal substrate combinations is (from best to worst): ZrNInc.825, ZrNHast.C22, ZrNTi, Si0.57C0.43Ti, Si0.57C0.43Hast.C22 and Si0.57C0.43Inc.825.

K.A Gruss; R.F Davis

1999-01-01T23:59:59.000Z

225

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

SciTech Connect (OSTI)

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

226

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

SciTech Connect (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

227

Saturation of light?induced defects in a?Si:H  

Science Journals Connector (OSTI)

The steady?state defect density in hydrogenated amorphous silicon (a?Si:H) under illumination was investigated for a wide range of illumination intensities and temperatures. The saturation defect density under illumination is both temperature and light intensity dependent. A chemical equilibrium model for light?induced defect generation is proposed. According to the model defect generation is enhanced under illumination due to the reduction of the defect formation energy when the bands are populated by photogenerated carriers. Defect generation is a self limiting process and the defect density reaches a saturation value at long illumination time despite the existence of an extended distribution of defect formation sites.

P. V. Santos; W. B. Jackson; R. A. Street

1991-01-01T23:59:59.000Z

228

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

SciTech Connect (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

229

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, R.B.

1987-05-01T23:59:59.000Z

230

Amorphous silicon technology  

SciTech Connect (OSTI)

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

231

Hole drift mobility measurements in amorphous silicon-carbon alloys Qing Gu, Qi Wang, and Eric A. Schiff  

E-Print Network [OSTI]

elsewhere.7s*`2 We also studied an unalloyed a-Si:H speci- men deposited at Energy Conversion Devices, Inc when noted, we used a laser wavelength of 500 nm to obtain carrier generation within about 1000

Schiff, Eric A.

232

Junction Transport in Epitaxial Film Silicon Heterojunction Solar Cells: Preprint  

SciTech Connect (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

233

Chemical vapor deposition of amorphous semiconductor films. Final subcontract report  

SciTech Connect (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

234

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

235

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

SciTech Connect (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

236

Gas Phase Diagnosis of Disilane/Hydrogen RF Glow Discharge Plasma and Its Application to High Rate Growth of High Quality Amorphous Silicon  

Science Journals Connector (OSTI)

Gas phase diagnosis of disilane/hydrogen plasma was carried out using mass spectrometry. At high growth rate (20 /s) conditions using pure disilane as a source gas, the partial pressure of disilane molecules measured by mass spectrometry was more than one order of magnitude higher than in the case when mono-silane was used as a source gas. The stability of amorphous silicon films prepared from disilane was improved by the hydrogen dilution technique, although the disilane partial pressure in this condition was much higher than in the case when mono-silane was used as a source gas for device quality films. The relation between the gas phase species and the stability of the resulting films is studied. It was found that increase in disilane related signal intensity do not decrease film stability directly.

Wataru Futako; Tomoko Takagi; Tomonori Nishimoto; Michio Kondo; Isamu Shimizu; Akihisa Matsuda

1999-01-01T23:59:59.000Z

237

Electronic Origin For The Phase Transition From Amorphous LixSi...  

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

lithiation, silicon transforms to amorphous LixSi (a-LixSi) via electrochemical driven solid state amorphization. With increasing lithium concentration, a-LixSi transforms to...

238

E-Print Network 3.0 - amorphous base alloy Sample Search Results  

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

1. On the one hand, stable amorphous alloy which leads to the change... of eutectic alloy amorphous silicon film. (b) SAD pattern of ... Source: Grigoriev, Alexei -...

239

E-Print Network 3.0 - amorphous kei kohinshitsu Sample Search...  

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

by metal diffusion... into amorphous silicon with the formation of metastable amorphous metal silicide. Supersaturation Source: Grigoriev, Alexei - Department of Materials...

240

Improvements in the structural and optical properties of a-Si:H by a dense plasma focus  

Science Journals Connector (OSTI)

Abstract Crystallization of hydrogenated amorphous silicon thin films with irradiation by using a dense plasma focus ion beam source has been investigated. The effects of the energetic ion beam irradiation on the surface morphological, structural and optical properties of the as-prepared a-Si:H thin films were investigated with field emission scanning electron microscopy, high resolution transmission electron microscopy, Raman scattering spectroscopy and mapping, and photoluminescence (PL) spectroscopy. The results show that irradiation of the energetic ion beam leads to the agglomeration of the Si grains with formation of Si nanocrystallites embedded within the amorphous matrix. This significantly enhances the optical properties of the film that it exhibits a wide range of PL emission spectra at room temperature.

Boon Tong Goh; Siew Kien Ngoi; Seong Ling Yap; Chiow San Wong; Saadah Abdul Rahman

2013-01-01T23:59:59.000Z

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

Comparative study of light absorption enhancement in ultrathin a-Si:H solar cells with conformal parabolaconical nanoarrays  

Science Journals Connector (OSTI)

Light trapping design is of critical importance for ultrathin a-Si:H solar cells. Three modelling methods are adopted for the amorphous silicon layer. The best modelling method is identified to achieve high-quality simulation results. Then, parabolaconical nanoarrays are introduced into ultrathin a-Si:H solar cells to study the design principle of high light absorption. Because a trade-off factor is often involved in solar cell consideration, light absorption is investigated for ultrathin a-Si:H solar cells with four conformal nanostructures, where a parabolaconical Ag nanoarray and a parabolaconical Al:ZnO nanoarray are included, respectively. Meanwhile, two height/radius ratios of 1 and 3 are considered, respectively. As a result, three promising structures and their respective optimal parameters are obtained. When the height/radius ratio is 1, the optimal absorption enhancement is 53.9% for a-Si:H solar cells with conformal parabolaconical Ag nanoarrays at a radius of 120?nm. When the height/radius ratio becomes 3, the optimal absorption enhancement is increased to 61.9% at a radius of 50?nm. Under the ratio of 3, it is found that the light absorption enhancement is 65.0% for the solar cells with conformal Al:ZnO nanoarrays. These design principles can provide an effective guide for the research and development of low-cost ultrathin a-Si:H solar cells.

Wensheng Yan; Min Gu

2014-01-01T23:59:59.000Z

242

Remarkable progress in thin-film silicon solar cells using high-efficiency triple-junction technology  

Science Journals Connector (OSTI)

Abstract Despite the many advantages of thin-film silicon (Si) solar cells, their low efficiencies remain a challenge that must be overcome. Efficient light utilization across the solar spectrum is required to achieve efficiencies over 15%, allowing them to be competitive with other solar cell technologies. To produce high-efficiency thin-film Si solar cells, we have developed triple-junction solar cell structures to enhance solar spectrum utilization. To maximize the light management, in-house ZnO:Al layers with high haze ratios and high transmittances were developed. In addition, novel doping layers, such as n-type microcrystalline silicon oxide (c-SiOx:H), which has a very low refractive index, and p-type microcrystalline silicon oxide (c-SiOx:H), which has a wide bandgap, were successfully applied to the optical reflector and the window layer, respectively. Thin-film quality control techniques for the deposition of hydrogenated amorphous silicon (a-Si:H) in the top cell, hydrogenated amorphous silicon-germanium (a-SiGe:H) or hydrogenated microcrystalline silicon (?c-Si:H) in the middle cell, and hydrogenated microcrystalline silicon (?c-Si:H) in the bottom cell were also important factors leading to the production of high-efficiency triple-junction solar cells. As a result of this work, an initial efficiency of 16.1% (in-house measurement) in the a-Si:H/a-SiGe:H/?c-Si:H stack and a stabilized efficiency of 13.4% (confirmed by NREL) in the a-Si:H/?c-Si:H/?c-Si:H stack were successfully achieved in a small-area triple-junction solar cell with dimensions of 1cm1cm.

Soohyun Kim; Jin-Won Chung; Hyun Lee; Jinhee Park; Younho Heo; Heon-Min Lee

2013-01-01T23:59:59.000Z

243

Simulated and measured data-line parasitic capacitance of amorphous silicon large-area image sensor arrays  

Science Journals Connector (OSTI)

Calculations and measurements of parasitic capacitance in active matrix sensor arrays used for light and x-ray imaging are presented. We focus on arrays with continuous sensor layers and base the calculations on actual structures used for x-ray and light imaging. Different cross sections of the pixel allow the various components of the capacitance from the thin film transistor the sensor and metal crossovers to be determined by numerical two-dimensional solution of Poissons equation. The calculations give the total and the individual components of the parasitic capacitance in the data line and allow us to evaluate their effect on electronic noise and imager sensitivity. The theoretical values are compared to measurements performed on arrays with 75 ?m pixel pitch showing agreement within 10%20%. The numerical simulations are used to determine the optimized array configuration that can reduce the parasitic capacitance to ?6 fF/pixel which is only 15% of the present values. The capacitance is compared for direct and indirect x-ray detectionimagers using PbI 2 and a- Si:H sensor layers respectively.

M. Mulato; J. P. Lu; R. A. Street

2001-01-01T23:59:59.000Z

244

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

SciTech Connect (OSTI)

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

245

Influence of base pressure and atmospheric contaminants on a-Si:H solar cell properties  

SciTech Connect (OSTI)

The influence of atmospheric contaminants oxygen and nitrogen on the performance of thin-film hydrogenated amorphous silicon (a-Si:H) solar cells grown by plasma-enhanced chemical vapor deposition at 13.56 MHz was systematically investigated. The question is addressed as to what degree of high base pressures (up to 10{sup -4} Torr) are compatible with the preparation of good quality amorphous silicon based solar cells. The data show that for the intrinsic a-Si:H absorber layer exists critical oxygen and nitrogen contamination levels (about 2x10{sup 19} atoms/cm{sup 3} and 4x10{sup 18} atoms/cm{sup 3}, respectively). These levels define the minimum impurity concentration that causes a deterioration in solar cell performance. This critical concentration is found to depend little on the applied deposition regime. By enhancing, for example, the flow of process gases, a higher base pressure (and leak rate) can be tolerated before reaching the critical contamination level. The electrical properties of the corresponding films show that increasing oxygen and nitrogen contamination results in an increase in dark conductivity and photoconductivity, while activation energy and photosensitivity are decreased. These effects are attributed to nitrogen and oxygen induced donor states, which cause a shift of the Fermi level toward the conduction band and presumably deteriorate the built-in electric field in the solar cells. Higher doping efficiencies are observed for nitrogen compared to oxygen. Alloying effects (formation of SiO{sub x}) are observed for oxygen contaminations above 10{sup 20} atoms/cm{sup 3}, leading to an increase in the band gap.

Woerdenweber, J.; Schmitz, R.; Mueck, A.; Zastrow, U.; Niessen, L.; Gordijn, A.; Carius, R.; Beyer, W.; Rau, U. [IEF 5 Photovoltaik, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany); Merdzhanova, T.; Stiebig, H. [IEF 5 Photovoltaik, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany); Malibu GmbH and Co. KG, Boettcherstr. 7, D-33609 Bielefeld (Germany)

2008-11-01T23:59:59.000Z

246

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

SciTech Connect (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

247

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

248

Design of plasmonic back structures for efficiency enhancement of thin-film amorphous Si solar cells  

Science Journals Connector (OSTI)

Metallic back structures with one-dimensional periodic nanoridges attached to a thin-film amorphous Si (a-Si) solar cell are numerically studied. At the interfaces between a-Si and...

Bai, Wenli; Gan, Qiaoqiang; Bartoli, Filbert; Zhang, Jing; Cai, Likang; Huang, Yidong; Song, Guofeng

2009-01-01T23:59:59.000Z

249

Reactivity and migration of hydrogen in a-Si:H  

SciTech Connect (OSTI)

Tight-binding molecular dynamics calculations reveal a new mechanism for hydrogen diffusion in hydrogenated amorphous silicon. Hydrogen diffuses through the network by successively bonding with nearby silicon and breaking their Si-Si bonds. The diffusing hydrogen carried with it a newly created dangling bond. These intermediate transporting states are densely populated in the network and have lower energies than H at the center of stretched Si-Si bonds.

Biswas, R.; Li, Q.; Pan, B.C.; Yoon, Y.

1997-07-01T23:59:59.000Z

250

Amorphous Photovoltaics  

Science Journals Connector (OSTI)

The only obstacle to the immediate widespread use of solar cells is the enormous cost of conventional crystalline-silicon solar cells. The problem lies in the production of crystalline-silicon arrays: ...

David Adler; Stanford R. Ovshinsky

1991-01-01T23:59:59.000Z

251

Amorphous Siliconbased Solar Cells Xunming Deng1  

E-Print Network [OSTI]

transistor), GaAs and the other III-V compounds (the basis for many light emitters), and CdS (often used with the silane. Just as for crystal silicon, the phosphorus doping of the amorphous silicon had induced a conductivity associated with mobile electrons (the material was "n-type"), and the boron doping had induced

Schiff, Eric A.

252

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

SciTech Connect (OSTI)

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

Demiro?lu, D.; Kazmanli, K.; Urgen, M. [Department of Metallurgical and Materials Engineering, Istanbul Technical University, Ayaza?a 34469, Istanbul (Turkey); Tatar, B. [Faculty of Arts and Sciences, Department of Physics, Nam?k Kemal University, De?irmenalt?, Tekirda? (Turkey)

2013-12-16T23:59:59.000Z

253

Characterization of Chemically Vapor Deposited Silicon Nitride Films from Disilane and Ammonia  

Science Journals Connector (OSTI)

Amorphous silicon nitride films a:SiNx were prepared by low pressure chemical vapor deposition (LPCVD) from disilane ( Si2H6) and ammonia ( NH3). Most of the depositions were performed at 600 C with various NH3/Si2H6 gas ratios ranging from 4 to 50. Different deposits with composition (x= N/Si) ranging from silicon-rich to stoichiometric silicon nitride were characterized by means of infrared spectroscopy (FTIR), ellipsometry, electron energy loss spectroscopy (EELS), and their structure analysed by transmission electron microscopy (TEM). Transmission infrared measurements showed low hydrogen content (x= N/Si) and density of the films were correlated with their refractive index and discussed.

Redhouane Henda; Larbi Laanab; Emmanuel Scheid; Robert Fourmeaux

1995-01-01T23:59:59.000Z

254

Polymorphism in Amorphous SiO2  

Science Journals Connector (OSTI)

Brillouin scattering from a-SiO2 up to 17 GPa shows that an irreversible change in the longitudinal sound velocity takes place between 10 and 17 GPa and that this change is stable at atmospheric pressure. Raman spectra of the retrieved sample indicate that it is also amorphous but differ noticeably from that of the original sample.

M. Grimsditch

1984-06-25T23:59:59.000Z

255

Numerical simulations for high efficiency HIT solar cells using microcrystalline silicon as emitter and back surface field (BSF) layers  

Science Journals Connector (OSTI)

Abstract In present article the influence of thickness and band gap of microcrystalline silicon emitter layer, amorphous silicon front and back intrinsic layers and p-type crystalline silicon (c-Si) wafer thickness on the performance of TCO/?c-Si:H(n)/a-Si:H(i)/c-Si(p)/a-Si:H(i)/?c-Si:H(p+)/Ag Heterojunction with thin intrinsic layer (HIT) solar cell along with other structural possibilities were investigated through computer simulations using AFORS-HET software. These simulations revealed the importance of inclusion of intrinsic a-Si:H thin layer in improving the performance of solar cell with the help of interface passivation. Also microcrystalline BSF can raise the conversion efficiency more than 4% compared to HIT solar cell having no BSF layer. Highest stable efficiency of 24.12% for p-type substrate based HITBSF (HIT with back surface field) solar cells was observed. Furthermore the effect of textured transparent conductive oxide (TCO) on solar cells was investigated where the enhanced light trapping was observed with the use of textured TCO surface which raised the performance of solar cells. These optimizations may help in fabricating ?c-Si emitter and BSF based HIT solar cells with stable efficiencies compared to possibly degraded efficiencies as in case of a-Si:H based HIT solar cell structures studied so far.

Arti Rawat; Mansi Sharma; Deepika Chaudhary; S. Sudhakar; Sushil Kumar

2014-01-01T23:59:59.000Z

256

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

SciTech Connect (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

257

Light-induced metastable defects or light-induced metastable H atoms in a-Si:H films?  

SciTech Connect (OSTI)

In hydrogenated amorphous silicon (a-Si:H) films, the increase of the metastable defect density under high-intensity illumination is usually described by an empirical two-parameter stretched-exponential time dependence (characteristic time {tau}{sub SE} and dispersion parameter {beta}). In this study, a clearly different (one-parameter) analytic function is obtained from a microscopic model based on the formation of metastable H (MSH) atoms in a-Si:H films. Assuming that MSH atoms are the only mobile species, only three chemical reactions are significant: MSH are produced from doubly hydrogenated (SiH HSi) configurations and trapped either at broken bonds or Si-H bonds, corresponding respectively to light-induced annealing (LIA) and light-induced creation (LIC) of defects. Competition between trapping sites results in a saturation of N(t) at a steady-state value N{sub ss}. A one-parameter fit of this analytical function to experimental data is generally good, indicating that the use of a statistical distribution of trap energies is not necessary.

Godet, C.

1997-07-01T23:59:59.000Z

258

Evidence for a wide continuum of polymorphs in a-SiO2  

Science Journals Connector (OSTI)

The irradiations of vitreous amorphous silica with subband-gap laser radiation at 248 nm induces reversible-irreversible compaction. The former is consistent with the creation of a wide continuum of densified amorphous silica (a-SiO2) polymorphs whilst the second stage corresponds to the ablation through laser radiation of the damaged a-SiO2. These observations are discussed in terms of conformational structure modifications (i.e., changes in the distribution of planar rings) and stable superficial defect creation.

C. Fiori and R. A. B. Devine

1986-02-15T23:59:59.000Z

259

Silicon Carbide, SiC  

Science Journals Connector (OSTI)

Silicon carbide occurring naturally as hexagonal crystals and associated with diamond, graphite, and amorphous carbon was first reported in 1904/05 by Moissan as a component of the hydrochloric acid insoluble ...

Vera Haase; Gerhard Kirschstein; Hildegard List; Sigrid Ruprecht

1985-01-01T23:59:59.000Z

260

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

SciTech Connect (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

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

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

SciTech Connect (OSTI)

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

Samiee, Mehran; Modtland, Brian; Dalal, Vikram L., E-mail: vdalal@iastate.edu [Iowa State University, Dept. of Electrical and Computer Engineering, Ames, Iowa 50011 (United States); Aidarkhanov, Damir [Nazarbayev University, Astana (Kazakhstan)

2014-05-26T23:59:59.000Z

262

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

SciTech Connect (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

263

Electroabsorption measurements and built-in potentials in amorphous silicongermanium solar cells  

E-Print Network [OSTI]

-1130 S. Guha and J. Yang United Solar Systems Corporation, 1100 West Maple Road, Troy, Michigan 48084Electroabsorption measurements and built-in potentials in amorphous silicon­germanium solar cells J spectra in n-i-p solar cells with hydrogenated amorphous silicon­germanium alloy absorber layers. At lower

Schiff, Eric A.

264

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

SciTech Connect (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

265

.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. 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

266

[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

267

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

Science Journals Connector (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 +?I?N + electrode cells and high work function metals improve V oc of substrate ?N?I?P cells. Typical V o c values are 760 mV with Cr Cu and AlN?I?Pstainless steel (SS) 700 mV with PdN?I?P?SS 600 mV with PdP?I?N?SS and 540 mV with CrP?I?N?SS. J 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 cm2solar cell.

Min?Koo Han; Wayne A. Anderson; R. Lahri; John Coleman

1981-01-01T23:59:59.000Z

268

A review on plasma-assisted VLS synthesis of silicon nanowires and radial junction solar cells  

Science Journals Connector (OSTI)

Incorporation of nanostructures is a recent trend in the photovoltaic community, aimed at improving light absorption and consequently cell efficiency. In this regard, semiconductor nanowires provide an attractive research platform for a new generation of cost-effective and efficient solar cells. Thanks to their unique geometry, silicon nanowires enhance light trapping and anti-reflection effects by means of multiple scattering between individual nanowires, and by coupling the light into confined eigenmodes over a broad range of the solar spectrum. Moreover, radial junction solar cells built around nanowires decouple the light absorption and carrier collection directions, which allows for a higher internal field and better carrier collection. Thus, arrays of radial junction solar cells bring advantages of high efficiency with reduced material amount. This is particularly attractive for devices based on hydrogenated amorphous and microcrystalline silicon thin films. In this paper, after reviewing different approaches to fabricate silicon nanowires, we focus on nanowires grown using the plasma-assisted vapourliquidsolid method because of the simplicity and compatibility with current silicon thin-film technology. Their application to a-Si?:?H based radial junction solar cells has already resulted in ~8% of stable devices with an absorber layer thickness of only 100nm. Moreover, current challenges and perspectives such as the use of a microcrystalline silicon absorber are also reviewed.

Soumyadeep Misra; Linwei Yu; Wanghua Chen; Martin Foldyna; Pere Roca i Cabarrocas

2014-01-01T23:59:59.000Z

269

Effective phase control of silicon films during high-rate deposition in atmospheric-pressure very high-frequency plasma: Impacts of gas residence time on the performance of bottom-gate thin film transistors  

Science Journals Connector (OSTI)

Abstract Hydrogenated amorphous silicon (a-Si) and microcrystalline silicon (?c-Si) films were grown in atmospheric-pressure (AP) He/H2/SiH4 plasma excited by a 150-MHz very high-frequency (VHF) power at a temperature of 220C. The variations in thickness and crystallinity of the deposited Si films along the gas flow direction were studied as functions of gas residence time in the plasma, VHF power density and H2 flow rate. Furthermore, the electrical characteristics of bottom-gate thin film transistors (TFTs) were investigated to evaluate the film quality. The results revealed that the chemical reactions both in gas phase and on the growing film surface were significantly enhanced in AP-VHF plasma, promoting phase transition from amorphous to microcrystalline in a time of the order of 0.1ms. The performance of the \\{TFTs\\} showed that a-Si layers formed in the upstream portion of the plasma zone had reasonably good electrical property (field-effect mobility of approximately 2cm2/Vs) despite very high deposition rates around 20nm/s. While ?c-Si layers deposited in the downstream portion were very defective, which might come from the insufficient passivation of grain boundaries with a-Si tissues due to a too long gas residence time in the plasma. The precise control of gas residence time by adjusting the length of plasma will be effective for the phase control of Si films with desired quality.

H. Kakiuchi; H. Ohmi; T. Yamada; A. Hirano; T. Tsushima; W. Lin; K. Yasutake

2013-01-01T23:59:59.000Z

270

JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 31, NO. 19, OCTOBER 1, 2013 3181 Noise Figure in Near-Infrared Amorphous and  

E-Print Network [OSTI]

JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 31, NO. 19, OCTOBER 1, 2013 3181 Noise Figure in Near-Infrared, Senior Member, IEEE Abstract--The noise figures (NF) of near-infrared (near-IR) amorphous silicon (a Amorphous and Mid-Infrared Crystalline Silicon Optical Parametric Amplifiers Jichi Ma and Sasan Fathpour

Fathpour, Sasan

271

Chemical-equilibrium model of optimal a-Si:H growth from SiH4  

Science Journals Connector (OSTI)

A model of optimal hydrogenated-amorphous-silicon growth based on bulk chemical reactions involving Si-Si and Si-H bonds is proposed. The optimal growth temperature is determined by the balance between the rate of hydrogen diffusion and the rate of film growth.

K. Winer

1990-04-15T23:59:59.000Z

272

Advanced Design of Broadband Distributed Amplifier using a SiGe BiCMOS Technology  

E-Print Network [OSTI]

Advanced Design of Broadband Distributed Amplifier using a SiGe BiCMOS Technology Gye-An Lee distributed amplifier for optical communication applications using SiGe BiCMOS technology. The design of some techniques are needed at such high frequencies. Main obstacles in the design of a silicon- based distributed

De Flaviis, Franco

273

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

SciTech Connect (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

274

Amorphous Silicon-Carbon Nanostructure Photovoltaic Devices  

E-Print Network [OSTI]

reductions in costs for installed photovoltaic systems. Thisreductions in costs for installed photovoltaic systems. Thisphotovoltaic technologies that improve upon current solutions by being lower cost,

Schriver, Maria Christine

2012-01-01T23:59:59.000Z

275

Amorphous Silicon-Carbon Nanostructure Photovoltaic Devices  

E-Print Network [OSTI]

2):11021108, 2012. [49] The Sunshot Program. One dollar per6-year period[57]. The Sunshot Initiative of the Department

Schriver, Maria Christine

2012-01-01T23:59:59.000Z

276

Amorphous Silicon-Carbon Nanostructure Photovoltaic Devices  

E-Print Network [OSTI]

fracking or of tar sands via destruction of pristine wilderness creates new threats to our personal and environmental health.

Schriver, Maria Christine

2012-01-01T23:59:59.000Z

277

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

278

Amorphous Silicon-Carbon Nanostructure Photovoltaic Devices  

E-Print Network [OSTI]

globally[5]. Total global energy use using past data andFigure 4.3 shows the total global energy use and predictions5]. Figure 4.3: Total global energy use using past data and

Schriver, Maria Christine

2012-01-01T23:59:59.000Z

279

Structure, Properties, and Dynamics of Oxygen Vacancies in Amorphous SiO2 Zhong-Yi Lu,1  

E-Print Network [OSTI]

Structure, Properties, and Dynamics of Oxygen Vacancies in Amorphous SiO2 Zhong-Yi Lu,1 C. J vacancies in SiO2 have long been regarded as bistable, forming a Si-Si dimer when neutral and a puckered configuration when positively charged. We report first-principles calculations of O vacancies in amorphous SiO2

Pantelides, Sokrates T.

280

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

SciTech Connect (OSTI)

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

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

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

282

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

283

Crystalline silicon growth in nickel/a-silicon bilayer  

SciTech Connect (OSTI)

The effect of substrate temperature on amorphous Silicon crystallization, mediated by metal impurity is reported. Bilayers of Ni(200nm)/Si(400nm) are deposited on fused silica substrate by electron beam evaporator at 200 and 500 Degree-Sign C. Raman mapping shows that, 2 to 5 micron size crystalline silicon clusters are distributed over the entire surface of the sample. X-ray diffraction and X-ray absorption spectroscopy studies demonstrate silicon crystallizes over the metal silicide seeds and grow with the annealing temperature.

Mohiddon, Md Ahamad; Naidu, K. Lakshun [School of Physics, University of Hyderabad, Hyderabad-500046 (India) and Department of Physics, University of Trento, 38123 POVO (Trento) (Italy); Dalba, G. [Department of Physics, University of Trento, 38123 POVO (Trento) (Italy); Rocca, F. [IFN-CNR, Institute for Photonics and Nanotechnologies, Unit FBK-Photonics of Trento, 38123, Trento (Italy); Krishna, M. Ghanashyam [School of Physics, University of Hyderabad, Hyderabad-500046 (India)

2013-02-05T23:59:59.000Z

284

Hydrogen populations in PECVD a-Si:H,D  

SciTech Connect (OSTI)

Proton NMR and deuteron NMR (DMR) have been used to measure hydrogen populations in a series of PECVD a-Si:H,D films. The sharp DMR doublet from Si-D is fitted and subtracted out. The residual spectra then show specific signatures for molecular D{sub 2} and HD. The fitting procedures yield quantitative measures of Si-bonded and molecular species. A particular comparison is made between a pair of films prepared as the powered and unpowered electrodes in the same plasma deposition. Both silicon-bonded and molecular populations are significantly different in the two films and correlate with photoresponse products {eta}{mu}{tau} and with IR as well as other materials characterizations.

Cull, T.S.; Kernan, M.J.; Chan, P.H.; Fedders, P.A.; Leopold, D.J.; Norberg, R.E.; Wickboldt, P.; Paul, W.

1997-07-01T23:59:59.000Z

285

Mass spectrometric study of NF3 plasma etching of silicon  

Science Journals Connector (OSTI)

NF3 plasma etching is used for dry cleaning of reactors after plasma-enhanced chemical vapor deposition of hydrogenated amorphous silicon from SiH4. The NF3 plasma chemistry, in a closed isothermal plasma box wit...

Jerome Perrin; Jacques Mot; Jean-Marie Sifert

1990-12-01T23:59:59.000Z

286

Wide-gap a-Si:H fabricated by controlling voids  

SciTech Connect (OSTI)

High quality wide gap hydrogenated amorphous silicon has been prepared using the chemical annealing technique. It was possible to prepare materials with band gaps ranging 1.8 to 2.1 eV by varying the preparation parameters. Low defect densities less than (3--8) {times} 10{sup 15} cm{sup {minus}3} could be maintained over the entire band gap range. Improved stability for light soaking was also observed in the wide gap materials.

Yoshino, K.; Futako, W.; Wasai, Y.; Shimizu, I. [Tokyo Inst. of Tech., Yokohama (Japan). Graduate School

1996-12-31T23:59:59.000Z

287

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

SciTech Connect (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

288

Amorphous diamond films  

DOE Patents [OSTI]

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

Falabella, S.

1998-06-09T23:59:59.000Z

289

Amorphous Medium Language  

E-Print Network [OSTI]

Programming reliable behavior on a large mesh network composed of unreliable parts is difficult. Amorphous Medium Language addresses this problem by abstracting robustness and networking issues away from the programmer via ...

Beal, Jacob

290

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

SciTech Connect (OSTI)

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

291

Understanding Why Silicon Anodes of Lithium-Ion Batteries Are...  

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

Understanding Why Silicon Anodes of Lithium-Ion Batteries Are Fast to Discharge but Slow to Charge December 02, 2014 Measured and calculated rate-performance of a Si thin-film (70...

292

Heterojunction solar cells produced by porous silicon layer transfer technology  

Science Journals Connector (OSTI)

In this paper, we present the result of heterojunction solar cells based on porous silicon layer transfer technology. a-Si/c-Si structured solar cells were prepared in which the c-Si ... was investigated. The spe...

Zhihao Yue; Honglie Shen; Lei Zhang; Bin Liu; Chao Gao; Hongjie Lv

2012-09-01T23:59:59.000Z

293

Silicone metalization  

DOE Patents [OSTI]

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

Maghribi, Mariam N. (Livermore, CA); Krulevitch, Peter (Pleasanton, CA); Hamilton, Julie (Tracy, CA)

2006-12-05T23:59:59.000Z

294

The Properties of Amorphous Boron  

Science Journals Connector (OSTI)

... few particles of amorphous boron are allowed to fall into fused potassium chlorate, quite a pyrotechnic display is produced. The behaviour of certain fluorides towards amorphous boron is interesting. Silver ...

A. E. TUTTON

1892-03-31T23:59:59.000Z

295

Laser Assisted Crystallization of Ferromagnetic Amorphous Ribbons...  

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

Ferromagnetic Amorphous Ribbons: A Multimodal Characterization and Thermal Model Study. Laser Assisted Crystallization of Ferromagnetic Amorphous Ribbons: A Multimodal...

296

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

297

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

SciTech Connect (OSTI)

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

Klossek, A.; Mankovics, D.; Ratzke, M. [Brandenburg University of Technology, Konrad-Wachsmann-Allee 1, D-03046 Cottbus (Germany)] [Brandenburg University of Technology, Konrad-Wachsmann-Allee 1, D-03046 Cottbus (Germany); Arguirov, T.; Kittler, M. [Brandenburg University of Technology, Konrad-Wachsmann-Allee 1, D-03046 Cottbus (Germany) [Brandenburg University of Technology, Konrad-Wachsmann-Allee 1, D-03046 Cottbus (Germany); IHP Microelectronics, Im Technologiepark 25, D-15236 Frankfurt (Oder) (Germany); Kirner, S.; Gabriel, O.; Stannowski, B.; Schlatmann, R. [Competence Centre Thin-Film- and Nanotechnology for Photovoltaics Berlin, Helmholtz-Zentrum Berlin, Berlin (Germany)] [Competence Centre Thin-Film- and Nanotechnology for Photovoltaics Berlin, Helmholtz-Zentrum Berlin, Berlin (Germany); Friedrich, F. [Competence Centre Thin-Film- and Nanotechnology for Photovoltaics Berlin, Helmholtz-Zentrum Berlin, Berlin (Germany) [Competence Centre Thin-Film- and Nanotechnology for Photovoltaics Berlin, Helmholtz-Zentrum Berlin, Berlin (Germany); Department of Semiconductor Devices, Technische Universitt Berlin, Sekr. E2, Einsteinufer 19, D-10587 Berlin (Germany)

2013-12-14T23:59:59.000Z

298

Diamond-Silicon Carbide Composite And Method For Preparation Thereof  

DOE Patents [OSTI]

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

Qian, Jiang (Los Alamos, NM); Zhao, Yusheng (Los Alamos, NM)

2005-09-06T23:59:59.000Z

299

Atomistic simulation of the interface structure of Si nanocrystals embedded in amorphous silica Flyura Djurabekova and Kai Nordlund*  

E-Print Network [OSTI]

Atomistic simulation of the interface structure of Si nanocrystals embedded in amorphous silica 11 February 2008; published 14 March 2008 An efficient means to obtain light emission from a silicon in industrial wafer manufacturing lines, this has opened up a promising avenue for using low-cost silicon chips

Nordlund, Kai

300

PECVD Silicon Carbide Waveguides for Multichannel G. Pandraud  

E-Print Network [OSTI]

PECVD Silicon Carbide Waveguides for Multichannel Sensors G. Pandraud Kavli Institute of Nano Deposition (PECVD) Silicon Carbide (SiC) waveguides. Thin SiC films have been deposited onto Si substrates with a SiO2 film acting as a cladding layer around the carbide core. In the sensor, the evanescent tale

Technische Universiteit Delft

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

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

302

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

303

Amorphous Binary Alloy Structures  

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

Hope Ishii, Sean Brennan and Arthur Bienenstock SSRL/SLAC 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

304

Holey Silicon as an Efficient Thermoelectric Material  

SciTech Connect (OSTI)

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

305

Synchroton x-ray diffraction study of an interfacial super-structure: a-Si on Ge0.2Si0.8 (111)-5 5  

Science Journals Connector (OSTI)

The interfacial structure between amorphous Si (a-Si) and Ge0.2Si0.8 is investigated by grazing incidence X-ray diffraction with the use of a synchroton radiation X-ray source. The sample, a-Si/Ge0.2Si0.8/Si(111) was prepared by molecular beam epitaxy. An a-Si film of 100 in thickness was deposited on the surface of Ge0.2Si0.8/Si(111), whose structure was 5 5 as confirmed by a RHEED pattern. The Bragg peaks of the X-ray diffraction wereobserved at (45, 45) and(?45, 85)in the two-dimensional reciprocal lattice space. This result indicates that the period of the 5 5 reconstructed surface structure is preserved even when the surface is covered with a-Si.

K. Akimoto; J. Mizuki; T. Tatsumi; N. Aizaki; J. Matsui

1987-01-01T23:59:59.000Z

306

Low temperature a - Si : H photodiodes and flexible image sensor arrays patterned by digital lithography  

Science Journals Connector (OSTI)

Hydrogenated amorphous silicon-based image sensor arrays were fabricated on polyethylene naphthalate substrates with photodiodes optimized for process temperatures of 150 C . An optimal i -layer thickness was determined to minimize carrier recombination and to maintain sufficient light absorption and acceptable leakage current. Patterning of the thin-film transistor backplane was accomplished using ink-jet printed etch masks. A flexible image sensor is demonstrated with 75 dots ? in. resolution over 180 180 pixels and with sensitivity of 1.2 pW ? cm 2 .

Tse Nga Ng; Rene A. Lujan; Sanjiv Sambandan; Robert A. Street; Scott Limb; William S. Wong

2007-01-01T23:59:59.000Z

307

Plasma deposition of wide gap, highly photoconductive a-Si:H thin films from disilane-helium mixtures  

SciTech Connect (OSTI)

Wide gap (>1.9 eV), photoconductive, intrinsic amorphous silicon films were made in a uhv system from Si/sub 2/H/sub 6/-He mixtures. The hydrogen concentrations, optical gaps and photoconductivities were measured. Unlike films made from SiH/sub 4/, Si/sub 2/H/sub 6/-produced films exhibit excellent electronic properties even at low deposition temperatures. The ratio of AM1 photoconductivity to dark conductivity was as high as 10/sup 7/.

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

1984-01-01T23:59:59.000Z

308

High rate (?3 nm/s) deposition of dense silicon nitride films at low substrate temperatures (plasma and substrate biasing  

Science Journals Connector (OSTI)

The deposition of amorphous silicon nitride (a-SiNx:H) films at high deposition rates (?3 nm/s) and at low substrate temperatures (plasma technique operated on an ArNH3SiH4 reactant mixture. To increase the atomic density of the films by ion bombardment, low frequency (lf, 400 kHz) and radio-frequency (rf, 13.6 MHz) substrate biasing has been employed during deposition such that the ions are accelerated towards the substrate up to energies of ?250 eV. From spectroscopic ellipsometry and Rutherford backscattering measurements, it is demonstrated that the film density increases with increasing substrate bias even under these high deposition rate conditions. An increase in film atomic density from 7.61022 cm?3 to 8.81022 cm?3 has been observed for rf biasing when going from almost zero substrate bias to a bias voltage of ?250 V. It is shown that this increased film density reduces the oxygen content in the a-SiNx:H caused by post-deposition oxygen and/or moisture permeation by more than 50%.

F.J.H. van Assche; W.M.M. Kessels; R. Vangheluwe; W.S. Mischke; M. Evers; M.C.M. van de Sanden

2005-01-01T23:59:59.000Z

309

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

SciTech Connect (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

310

Magnetism in amorphous transition metals  

Science Journals Connector (OSTI)

Overall features of magnetism in amorphous transition metals have been investigated on the basis of a finite-temperature theory of the local-environment effect. It is shown that the simple ferromagnetism of Fe, Co, and Ni is drastically changed by structural disorder; amorphous transition metals form spin glasses (SGs) for compositions near amorphous Fe (6.7?N?7.35), ferromagnets for compositions near amorphous Co (7.35?N?9.0), and paramagnetisms for compositions near amorphous Ni (9.0?N?10.0) where N is the number of d electrons. The SG is accompanied by formation of local ferromagnetic clusters for N?7.2, and shows reentrant behavior at the ferromagnetic boundary N?7.35. The ferromagnetism in amorphous transition metals is shown to be well explained by the main-peak position in the noninteracting densities of states. It is found that structural disorder enhances the Curie temperatures (TC) in the range 7.9?N?8.5 as compared with bcc and fcc structures. These results explain recent experimental data for the SG in Fe-rich amorphous alloys and the high TC in amorphous Co-Y alloys, but they are quite different from the early picture obtained for amorphous transition-metalmetalloid alloys.

Y. Kakehashi

1991-05-01T23:59:59.000Z

311

Programming an Amorphous Computational Medium  

E-Print Network [OSTI]

Amorphous computing considers the problem of controllingmillions of spatially distributed unreliable devices which communicateonly with nearby neighbors. To program such a system, we need a highleveldescription language ...

Beal, Jacob

312

Polycrystalline silicon thin-film solar cells on glass by ion-assisted deposition.  

E-Print Network [OSTI]

??Polycrystalline silicon (pc-Si, grain size > 1??m, no amorphous tissue) on glass is an interesting material for thin-film solar cells due to the low costs, (more)

Straub, Axel

2005-01-01T23:59:59.000Z

313

Interaction potential for silicon carbide: A molecular dynamics study of elastic constants and vibrational density of states for crystalline  

E-Print Network [OSTI]

Interaction potential for silicon carbide: A molecular dynamics study of elastic constants and vibrational density of states for crystalline and amorphous silicon carbide Priya Vashishta,a Rajiv K. Kalia Silicon carbide SiC has been proposed for a wide range of technological applications

Southern California, University of

314

Silicon-germanium saturable absorbers and erbium-doped waveguides for integrated mode-locked lasers  

E-Print Network [OSTI]

In this thesis, Silicon-Germanium (SiGe) Saturable Bragg Reflectors (SBR) and Erbium-doped waveguide chips are fabricated and characterized as crucial components for integration of a mode-locked laser on a Si-chip. The ...

Byun, Hyunil

2006-01-01T23:59:59.000Z

315

Boron- and phosphorus-doped polycrystalline silicon thin films prepared by silver-induced layer exchange  

SciTech Connect (OSTI)

Intentional boron and phosphorus doping of polycrystalline silicon thin films on glass prepared by the silver-induced layer exchange is presented. A silver/(titanium) oxide/amorphous silicon stack is annealed at temperatures below the eutectic temperature of the Ag/Si system, leading to a complete layer exchange and simultaneous crystallization of the amorphous silicon. Intentional doping of the amorphous silicon prior to the exchange process results in boron- or phosphorus-doped polycrystalline silicon. Hall effect measurements show carrier concentrations between 2 Multiplication-Sign 10{sup 17} cm{sup -3} and 3 Multiplication-Sign 10{sup 20} cm{sup -3} for phosphorus and 4 Multiplication-Sign 10{sup 18} cm{sup -3} to 3 Multiplication-Sign 10{sup 19} cm{sup -3} for boron-doped layers, with carrier mobilities up to 90 cm{sup 2}/V s.

Antesberger, T.; Wassner, T. A.; Jaeger, C.; Algasinger, M.; Kashani, M.; Scholz, M.; Matich, S.; Stutzmann, M. [Walter Schottky Institut and Physics Department, Technische Universitaet Muenchen, Am Coulombwall 4, 85748 Garching (Germany)] [Walter Schottky Institut and Physics Department, Technische Universitaet Muenchen, Am Coulombwall 4, 85748 Garching (Germany)

2013-05-27T23:59:59.000Z

316

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

DOE Patents [OSTI]

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

Branagan, Daniel J. (Idaho Falls, ID); Hyde, Timothy A. (Idaho Falls, ID); Fincke, James R. (Los Alamos, NM)

2008-03-11T23:59:59.000Z

317

Phonon Heat Conduction in Corrugated Silicon Nanowires Below the Casimir Limit Christophe Blanc,1  

E-Print Network [OSTI]

very low thermal conductances of highly rough silicon nanowires [7, 18], far below the amorphous limit, 2013) The thermal conductance of straight and corrugated monocrystalline silicon nanowires has been of nanostructured materials or low dimen- sional materials has attracted growing interest [1­4], es- pecially

Paris-Sud XI, Université de

318

Fabrication of amorphous diamond films  

DOE Patents [OSTI]

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

Falabella, S.

1995-12-12T23:59:59.000Z

319

Surface and Coatings Technology 171 (2003) 4650 0257-8972/03/$ -see front matter 2003 Elsevier Science B.V. All rights reserved.  

E-Print Network [OSTI]

amorphous silicon carbide (a-SiC:H) and crystalline silicon carbide (c-SiC) with different compositions were deposited on Si(1 0 0) substrates by both RF plasma enhanced chemical vapor deposition and thermal metal-PECVD; Thermal MOCVD 1. Introduction Hydrogenated amorphous silicon carbide (a-SiC:H) films are widely used

Boo, Jin-Hyo

320

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

SciTech Connect (OSTI)

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

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.


321

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

322

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

DOE Patents [OSTI]

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

323

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

DOE Patents [OSTI]

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

324

Single-crystal germanium growth on amorphous silicon  

E-Print Network [OSTI]

The integration of photonics with electronics has emerged as a leading platform for microprocessor technology and the continuation of Moore's Law. As electronic device dimensions shrink, electronic signals encounter crippling ...

McComber, Kevin A

2011-01-01T23:59:59.000Z

325

Atomic Layer Deposition for Stabilization of Amorphous Silicon Anodes  

Broader source: Energy.gov [DOE]

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

326

Energy dependence of defects in a-Si:H solar cells during degradation and annealing processes  

SciTech Connect (OSTI)

In this work the authors report on the effect of current-induced degradation and annealing on p-i-n amorphous silicon solar cells. Current-voltage curves and capacitance measurements under forward bias have been used to monitor the current-induced changes as a function of time. They found that the recovery rate increases with the annealing current, while the stabilized value of efficiency decreases. Comparison of short circuit current and capacitance evolution suggests that defect kinetics in the electronic gap occurs in a different way during degradation and annealing. This behavior can be modeled assuming a faster annealing of defects closest to the extended band and a slower annealing of mid-gap defects.

Caputo, D.; Lemmi, F.; Palma, F.

1997-07-01T23:59:59.000Z

327

Super?bandgap radiation in a?Si  

Science Journals Connector (OSTI)

The nature of the super?bandgap radiation observed in a?Si and a?Si:H is investigated. This broad spectrum postulated to arise from localized states above the mobility gap exhibits many remarkable features. These same features occur in radiation from porous quartz but in that case the effect is known to be surface related.2 Using the Raman spectrum for calibration the strength of the signal from a?Si has been studied as a function of surface preparation. The results suggest the possibility that the radiation is a surface contaminant effect unrelated to the bulk states of the material.

B. A. Wilson

1981-01-01T23:59:59.000Z

328

D0 silicon trackers  

SciTech Connect (OSTI)

The present Fermilab D0 silicon microstrip tracker, the silicon microstrip tracker which was designed to replace it, and plans for upgrading the present silicon tracker are described.

W. E. Cooper

2003-12-19T23:59:59.000Z

329

Plasma deposition of wide gap, highly photoconductive a-Si:H thin films from disilane-helium mixtures  

SciTech Connect (OSTI)

Wide gap (> 1.9 eV), photoconductive, intrinsic amorphous silicon films were made in a UHV system from Si/sub 2/H/sub 6/-He mixtures. The hydrogen concentrations, optical gaps and photoconductivities were measured. Unlike films made from SiH/sub 4/, Si/sub 2/H/sub 6/-produced films exhibit excellent electronic properties even at low deposition temperatures. The ratio of AM1 photoconductivity to dark conductivity was as high as 10/sup 7/. 17 references, 5 figures, 1 table.

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

1985-01-01T23:59:59.000Z

330

Specific features of recombination in layered a-Si:H films  

SciTech Connect (OSTI)

The absorbed light spectral composition determines the type of carrier generation: interband generation or mixed generation that also includes the generation of electrons from levels of the valence-band tail. The generation type affects the value and temperature dependence of the electron recombination rate in a-Si:H layered films. This effect is caused by a variation in the occupation of the levels of silicon dangling bonds and the valence band tail with electrons upon a change in the carrier generation type. As a result, in the case of mixed carrier generation in the investigated films with a low concentration of native dangling bonds, electron recombination in the films is slow and recombination at the levels of the valence-band tail can prevail up to room temperature.

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

2012-03-15T23:59:59.000Z

331

Silicon heterojunction solar cell with passivated hole selective MoO{sub x} contact  

SciTech Connect (OSTI)

We explore substoichiometric molybdenum trioxide (MoO{sub x}, x?silicon solar cells. Using an intrinsic hydrogenated amorphous silicon passivation layer between the oxide and the silicon absorber, we demonstrate a high open-circuit voltage of 711?mV and power conversion efficiency of 18.8%. Due to the wide band gap of MoO{sub x}, we observe a substantial gain in photocurrent of 1.9?mA/cm{sup 2} in the ultraviolet and visible part of the solar spectrum, when compared to a p-type amorphous silicon emitter of a traditional silicon heterojunction cell. Our results emphasize the strong potential for oxides as carrier selective heterojunction partners to inorganic semiconductors.

Battaglia, Corsin; Yin, Xingtian; Zheng, Maxwell; Javey, Ali, E-mail: ajavey@eecs.berkeley.edu [Electrical Engineering and Computer Sciences Department, University of California, Berkeley, California 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Martn de Nicols, Silvia; De Wolf, Stefaan; Ballif, Christophe [Photovoltaics and Thin Film Electronics Laboratory, Ecole Polytechnique Fdrale de Lausanne, 2000 Neuchtel (Switzerland)

2014-03-17T23:59:59.000Z

332

Study of the [(Co45Fe45Zr10)x(Al2O3)100?x/a-Si:H]m multilayer nanostructure by polarized neutron reflectometry  

Science Journals Connector (OSTI)

Polarized neutron reflectometry was used to investigate the amorphous multilayer nanostructures [(Co45Fe45Zr10)x(Al2O3)100?x/a-Si:H]m, whose magnetic properties are dependent on the concentration of the magnetic constituent (x=34, 47 and 60at%) as well as on the thicknesses of the metal-dielectric (Co45Fe45Zr10)x(Al2O3)100?x and semiconductor a-Si:H layers. The average magnetization of the individual magnetic layer is found to be inhomogeneous with the magnetically active central part and two magnetically dead parts at the interfaces.

E.A. Dyadkina; S.V. Grigoriev; D. Lott; A.V. Sitnikov; Y.E. Kalinin

2011-01-01T23:59:59.000Z

333

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 (OSTI)

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

334

Calculations of the Electronic and Transport Properties in Si-Ge-H Alloys  

Science Journals Connector (OSTI)

In previous work1,2..., we have obtained an understanding of the role of hydrogen in amorphous silicon (a-Si) performing first principles calculations of the electronic and transport properties of a-Si:H...

D. A. Papaconstantopoulos; E. N. Economou

1985-01-01T23:59:59.000Z

335

Stability and the Amorphous State  

E-Print Network [OSTI]

. Brabender Plasticorder twin screw lab scale extruder 18 Indomethacin / PVP extrudate Tolbutamide / PVP (1:1) 19 NCE Select excipient Thermally stable? Dissolution rate Recrystallisation Small-scale fusion Yes One Tg? Yes Scale up preparation Yes.... stab. of beaker melts and extrudates 29 APV twin screw lab extruder NCE Select excipient Thermally stable? Dissolution rate Recrystallisation Small-scale fusion Yes One Tg? Yes Scale up preparation Yes Stability studies Yes Amorphous? Small...

Rades, T.

2006-10-26T23:59:59.000Z

336

New Model for Amorphous Magnetism  

Science Journals Connector (OSTI)

We propose a new model for magnetism in an amorphous material. The model is particularly appropriate for rare-earth compounds such as TbF2. It is a Heisenberg model in which each ionic spin is subjected to a local anisotropy field of random orientation. We discuss the magnetic properties of two simple ionic configurations, and show that the model is in qualitative agreement with the experimental data.

R. Harris; M. Plischke; M. J. Zuckermann

1973-07-16T23:59:59.000Z

337

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

338

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

339

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

SciTech Connect (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

340

Polycrystalline Silicon Solar Cells Fabricated by Pulsed Rapid Thermal Annealing of Amorphous Silicon  

E-Print Network [OSTI]

). The gas supply into the reactor through the mass flow controllers include: N2 (ultra high purity, Acetylene Oxygen Company), N2 (semiconductor, 99.9999% purity, Praxair), Ar (semiconductor, 99.9999% purity, Praxair), SiH4 (semiconductor, 99.999% Air... Liquide), B2H6 (2 % in H2, 99.999% purity, Air Liquide), PH3 (7.1 % in H2, 99.999%, Air Liquide), NH3 (semiconductor, 99.999% purity, Matheson Tri-Gas), and H2 (semiconductor, 99.9999% purity, Praxair). Figure 4 shows the heating zones and the dimension...

Lee, I-Syuan

2014-05-07T23:59:59.000Z

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

Electrical Properties of MetalSilicon NitrideHydrogenated Amorphous Silicon Capacitor Elucidated Using Admittance Spectroscopy  

E-Print Network [OSTI]

Tung University, Hsinchu, Taiwan 300, Republic of China 2 AU Optronics Corporation, Technology Center

342

Formation of Supercooled Liquid Solutions from Nanoscale Amorphous...  

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

Supercooled Liquid Solutions from Nanoscale Amorphous Solid Films of Methanol and Ethanol. Formation of Supercooled Liquid Solutions from Nanoscale Amorphous Solid Films of...

343

Electron-Stimulated Production of Molecular Oxygen in Amorphous...  

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

Water. Electron-Stimulated Production of Molecular Oxygen in Amorphous Solid Water. Abstract: The low-energy, electron-stimulated production of molecular oxygen from pure amorphous...

344

Infrared Spectroscopy and Optical Constants of Porous Amorphous...  

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

Spectroscopy and Optical Constants of Porous Amorphous Solid Water. Infrared Spectroscopy and Optical Constants of Porous Amorphous Solid Water. Abstract: Reflection-absorption...

345

Structure, Morphology, and Optical Properties of Amorphous and...  

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

Morphology, and Optical Properties of Amorphous and Nanocrystalline Gallium Oxide Thin Films. Structure, Morphology, and Optical Properties of Amorphous and Nanocrystalline Gallium...

346

Intermediate layers in the a-Si:H growth processes  

SciTech Connect (OSTI)

The intermediate layers (IL) exist at the boundary between liquid (plasma, gas) and solid phases during production processes of a-Si:H. The IL properties differ from the properties of the boundary regions anomaly. The substance in IL is in a strong nonequilibrium state of the bifurcation or the cascade of bifurcations. The processes in the IL determine the properties and the structure of the material being produced.

Aivazov, A.A.; Bodyagin, N.V. [Moscow Inst. of Electronic Technology (Russian Federation); Vikhrov, S.P. [Radiotechnical Academy, Ryazan (Russian Federation). CR Faculty

1996-12-31T23:59:59.000Z

347

Calculations of the electronic properties of hydrogenated silicon  

Science Journals Connector (OSTI)

We have used the coherent potential approximation to calculate the electronic densities of states for a model of hydrogenated amorphous silicon. The results demonstrate the restoration and widening of the band gap with increasing hydrogen content. In the valence band, excellent agreement with photoemission experiments is obtained. In the conduction band Si-H antibonding states are predicted that can be inferred from photoconductivity measurements.

D. A. Papaconstantopoulos and E. N. Economou

1981-12-15T23:59:59.000Z

348

Role of material structure on molecular diffusion of hydrogen in a-Si:C:H films  

SciTech Connect (OSTI)

The authors used Fourier Transform Infra-Red (FTIR) analysis of bi-layers of plasma-grown hydrogenated amorphous silicon-carbide films to investigate the role of the material structure in the hydrogen diffusion process. In the bi-layers one layer was deposited using CH{sub 4}/SiH{sub 4} and in the other layer CD{sub 4}/SiD{sub 4} was applied. The carbon concentration was 20 at.%. In previous work they showed, using Elastic Recoil Detection (ERD) and Thermal Desorption Spectrometry (TDS), that the hydrogen moves molecular through these films in the temperature range 325 < T < 450 C. Using FTIR they obtained information about the number of Si-H and Si-D bonds and their change upon annealing. The FTIR data indicate a structural change during annealing. A comparison with the TDS spectra led them to the conclusion that at higher temperatures the out-diffusion of hydrogen stops because of the hindrance of the molecular transport.

Ullersma, E.H.C.; Inia, D.K.; Habraken, F.H.P.M.; Van Sark, W.G.J.H.M.; Van der Weg, W.F.; Westerduin, K.T.; Van Veen, A.

1997-07-01T23:59:59.000Z

349

Received 13 May 2013 | Accepted 18 Nov 2013 | Published 16 Dec 2013 All-back-contact ultra-thin silicon nanocone solar  

E-Print Network [OSTI]

. In particular, a silicon (Si) solar cell is still the mainstream technology in industry, and it has witnessed-thin silicon nanocone solar cells with 13.7% power conversion efficiency Sangmoo Jeong1, Michael D. McGehee2 & Yi Cui2,3 Thinner Si solar cells with higher efficiency can make a Si photovoltaic system a cost

Cui, Yi

350

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

SciTech Connect (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

351

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

SciTech Connect (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

352

Thin silicon solar cells  

SciTech Connect (OSTI)

The silicon-film design achieves high performance by using a dun silicon layer and incorporating light trapping. Optimally designed thin crystalline solar cells (<50 microns thick) have performance advantages over conventional thick devices. The high-performance silicon-film design employs a metallurgical barrier between the low-cost substrate and the thin silicon layer. Light trapping properties of silicon-film on ceramic solar cells are presented and analyzed. Recent advances in process development are described here.

Hall, R.B.; Bacon, C.; DiReda, V.; Ford, D.H.; Ingram, A.E.; Cotter, J.; Hughes-Lampros, T.; Rand, J.A.; Ruffins, T.R.; Barnett, A.M. [Astro Power Inc., Solar Park, Newark, DE (United States)

1992-12-01T23:59:59.000Z

353

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

SciTech Connect (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

354

E-Print Network 3.0 - a-si alloy solar Sample Search Results  

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

1m intrinsic a-Si:H layers were... intrinsic a-Si:H layer and the metal film. For the solar cell test, the light is coming from the bottom... through structure innovations....

355

Plasma synthesis of single-crystal silicon nanoparticles for novel electronic device applications  

Science Journals Connector (OSTI)

Single-crystal nanoparticles of silicon, several tens of nanometres in diameter, may be suitable as building blocks for single-nanoparticle electronic devices. Previous studies of nanoparticles produced in low-pressure plasmas have demonstrated the synthesis of nanocrystals 210?nm diameter but larger particles were amorphous or polycrystalline. This work reports the use of a constricted, filamentary capacitively coupled low-pressure plasma to produce single-crystal silicon nanoparticles with diameters between 20 and 80?nm. Particles are highly oriented with predominantly cubic shape. The particle size distribution is rather monodisperse. Electron microscopy studies confirm that the nanoparticles are highly oriented diamond-cubic silicon.

Ameya Bapat; Curtis Anderson; Christopher R Perrey; C Barry Carter; Stephen A Campbell; Uwe Kortshagen

2004-01-01T23:59:59.000Z

356

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research  

E-Print Network [OSTI]

of hydrogenated amorphous silicon (a-Si:H) films is critically influenced by the hydrogen/silane ratio during (a-Si:H) films. The passivation quality of such a-Si:H films is critically influenced by the hydrogen for very high hydrogen/silane ratios. 2. Experiments For the a-Si:H depositions we use a CS 400P PECVD

357

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

DOE Patents [OSTI]

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

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

2014-07-15T23:59:59.000Z

358

Direct Observation of Amorphous to Amorphous Apparently First-Order Phase Transition in Fused Quartz  

Science Journals Connector (OSTI)

We report for the first time the direct observation of an apparently first-order phase transition in amorphous silica from the low density amorphous phase to the high density amorphous phase with a discontinuous volume change of about 20% from the dilatometric measurements using the piston cylinder apparatus at 36 kbar and 680 C. Our Raman spectroscopy measurements on the retrieved samples quenched from high pressure and high temperature experiments do not show any Raman peaks indicating a large modification in the intermediate range order in the structure of amorphous silica.

G. D. Mukherjee; S. N. Vaidya; V. Sugandhi

2001-10-16T23:59:59.000Z

359

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

360

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

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

Defect formation mechanism during PECVD of a-Si:H  

SciTech Connect (OSTI)

Defect formation mechanism in a-Si:H during PECVD at substrate temperature below 250 C is considered to be breaking of weak bonds in the Urbach tail. To break weak bonds, an extra energy is necessary. This energy is supplied by the reaction energy of SiH{sub 3} precursor at the growing surface incorporating SiH{sub 2} into the network. The defect density is experimentally shown to be proportional to a product of the energy supply frequency, i.e., SiH{sub 2} density, and the weak bond density which is obtained by the Urbach energy. By analysis using the configurational coordinate diagram the energy level of the broken weak bond is determined to be 0.2 eV above the valence band mobility edge. There is similarity of the defect formation mechanism during deposition to that of the Staebler-Wronski effect.

Maeda, Keiji; Umezu, Ikurou

1997-07-01T23:59:59.000Z

362

OPTIMIZATION OF a-SiGe BASED TRIPLE, TANDEM AND SINGLE-JUNCTION SOLAR Xunming Deng  

E-Print Network [OSTI]

at the University of Toledo (UT) in the fabrication of high-efficiency triple, tandem and single-junction solar with 12.5% initial efficiency and 10.7% stable efficiency, tandem-junction a-Si/a-SiGe solar cells with 12.9% initial efficiency, and single-junction a-SiGe solar cells with 12.5-13% initial efficiency and 10

Deng, Xunming

363

Direct Evidence of Lithium-Induced Atomic Ordering in Amorphous...  

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

Evidence of Lithium-Induced Atomic Ordering in Amorphous TiO2 Nanotubes . Direct Evidence of Lithium-Induced Atomic Ordering in Amorphous TiO2 Nanotubes . Abstract: In this paper,...

364

Applications in the Nuclear Industry for Thermal Spray Amorphous Metal and Ceramic Coatings  

E-Print Network [OSTI]

SAW Amorphous metal and ceramic thermal spray coatings havefor Thermal Spray Amorphous Metal and Ceramic Coatings J.

Blink, J.; Farmer, J.; Choi, J.; Saw, C.

2009-01-01T23:59:59.000Z

365

Results of a Si/CdTe Compton Telescope  

E-Print Network [OSTI]

We have been developing a semiconductor Compton telescope to explore the universe in the energy band from several tens of keV to a few MeV. We use a Si strip and CdTe pixel detector for the Compton telescope to cover an energy range from 60 keV. For energies above several hundred keV, the higher efficiency of CdTe semiconductor in comparison with Si is expected to play an important role as an absorber and a scatterer. In order to demonstrate the spectral and imaging capability of a CdTe-based Compton Telescope, we have developed a Compton telescope consisting of a stack of CdTe pixel detectors as a small scale prototype. With this prototype, we succeeded in reconstructing images and spectra by solving the Compton equation from 122 keV to 662 keV. The energy resolution (FWHM) of reconstructed spectra is 7.3 keV at 511 keV and 3.1 keV at 122 keV, respectively. The angular resolution obtained at 511 keV is measured to be 12.2 degree (FWHM).

Kousuke Oonuki; Takaaki Tanaka; Shin Watanabe; Shin'ichiro Takeda; Kazuhiro Nakazawa; Takefumi Mitani; Tadayuki Takahashi; Hiroyasu Tajima; Yasushi Fukazawa; Masaharu Nomachi

2005-09-21T23:59:59.000Z

366

Diamond Lattice Model of Semicrystalline Polyethylene in the Amorphous Region  

E-Print Network [OSTI]

Diamond Lattice Model of Semicrystalline Polyethylene in the Amorphous Region Zhong­Hui Duan Abstract The statistics of polyethylene chains in the amorphous region between two crystallites have been as models of the chain molecules in the amorphous region of semicrystalline polyethylene, both

Aluffi, Paolo

367

Dense colloidal fluids form denser amorphous sediments  

E-Print Network [OSTI]

Dense colloidal fluids form denser amorphous sediments Shir R. Libera,b , Shai Borohovicha of their randomly packed solid sediments. We demonstrate that the most dilute fluids of colloidal hard spheres form loosely packed sediments, where the volume fraction of the particles approaches in frictional systems

Schofield, Andrew B.

368

Functionalized Silicone Nanospheres: Synthesis, Transition Metal...  

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

Functionalized Silicone Nanospheres: Synthesis, Transition Metal Immobilization, and Catalytic Applications. Functionalized Silicone Nanospheres: Synthesis, Transition Metal...

369

Highly Efficient Silicon Light Emitting Diode  

E-Print Network [OSTI]

silicon light-emitting diodes (LED) that efficiently emit photons with energy around the silicon bandgap

Leminh Holleman Wallinga; P. Leminh; J. Holleman; H. Wallinga

2000-01-01T23:59:59.000Z

370

SOLAR MARKET POWERS SILICON  

Science Journals Connector (OSTI)

SOLAR MARKET POWERS SILICON ... Polysilicon shortages are boon to manufacturers, bane of solar energy industry ... Solar energy is a relatively new market for polysilicon manufacturers. ...

JEAN-FRA&CCEDIL;NOIS TREMBLAY

2006-10-02T23:59:59.000Z

371

Micromachined silicon electrostatic chuck  

DOE Patents [OSTI]

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

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

1996-12-10T23:59:59.000Z

372

Large Area and High Efficiency a-Si:H Solar Cell  

Science Journals Connector (OSTI)

A conversion efficiency of 5.4% for a-Si:H solar cell on 10x10 cm2...stainless steel substrate has been obtained. Large area a-Si:H solar cells were fabricated by the C-coupled...2...parallel plates) glow dischar...

Y. Higaki; M. Kato; M. Aiga

1982-01-01T23:59:59.000Z

373

Layer-thickness dependence of cw photoluminescence in single a-Si:H layers  

Science Journals Connector (OSTI)

Photoluminescence data are presented for ultrathin single layers of a-Si:H deposited on a-SiO2. We observe a nonmonotonic shift of the luminescence peak with layer thickness, indicating that more than one mechanism is operative. Possible sources of the opposing shifts are discussed.

B. A. Wilson; C. M. Taylor; J. P. Harbison

1986-09-15T23:59:59.000Z

374

Characterization of UHV E-beam Evaporated Low-Stress Thick Silicon Film for MEMS Application  

Science Journals Connector (OSTI)

This paper investigates various deposition and subsequent processing conditions on UHV e-beam evaporated silicon to obtain low stress film. They include substrate temperature, deposition rate, annealing, thermal oxidation and post-oxidation annealing. Film stress is measured for each condition and cantilever beams made from the films are released for evaluating stress-gradient. Films are also deposited on sloped step structures to observe step and corner coverage. The results indicate that as-deposited evaporated silicon exhibits tensile stress at substrate temperatures below 400?C and compressive stress as substrate temperature is increased above 400?C for a 100nm/min deposition rate. For evaporated amorphous silicon films, performing thermal oxidation at 900?C and annealing at elevated temperatures has been found to be effective in reducing film stress. For fully crystallized poly-silicon films, however, annealing at 1000?C without thermal oxidation seems to be the more effective way of reducing stress in the film.

A. Michael; O. Kazuo; Y.W. Xu; C.Y. Kwok; T. Puzzer; S. Varlamov

2012-01-01T23:59:59.000Z

375

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

376

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

377

Optical and structural characterization of silicon microstructures fabricated by laser interference crystallization  

SciTech Connect (OSTI)

Uniform gratings of sharply defined polycrystalline silicon lines with micrometer-sized periods were created by laser interference crystallization of amorphous silicon. Atomic force microscopy (AFM) reveals that lines fabricated with high pulse energies (380 mJ/cm{sup 2}) contain large grains (dimensions up to 1.5 {micro}m), growing in a direction perpendicular to the lines. The authors assign this strong lateral growth to the melting of the material in the center of the lines combined with the presence of small grains, which act as nuclei, at the interfaces with the amorphous regions. Spatially resolved Raman spectroscopy shows that size effects dominate the Raman line shape at the edge of the line, confirming the AFM results, while stress increases towards the center of the line. The spectra measured in the middle of lines created with high energies show doping effects caused by the diffusion of boron atoms from the substrate upon exposure.

Toet, D.; Aichmayr, G.; Mulato, M.; Santos, P.V.; Spangenberg, A.; Bergmann, R.B.

1997-07-01T23:59:59.000Z

378

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

379

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  

SciTech Connect (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

380

Thermally Oxidized Silicon  

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

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

Germanium detector passivated with hydrogenated amorphous germanium  

DOE Patents [OSTI]

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

Hansen, William L. (Walnut Creek, CA); Haller, Eugene E. (Berkeley, CA)

1986-01-01T23:59:59.000Z

382

Diffusion and effusion of hydrogen in microcrystalline silicon  

SciTech Connect (OSTI)

The diffusion and effusion of hydrogen in hydrogenated microcrystalline silicon films deposited in an electron cyclotron resonance reactor were studied for various deposition temperatures T{sub s}. For deposition temperatures below 250 C, hydrogen effusion is found to be dominated by desorption of hydrogen from internal surfaces followed by rapid out-diffusion of H{sub 2}. Higher substrate temperatures result in an increased hydrogen stability suggesting the growth of a more compact material. For this latter type of samples, a hydrogen diffusion coefficient similar as in compact plasma-grown a-Si:H films is found despite a different predominant bonding of hydrogen according to infrared absorption.

Beyer, W.; Hapke, P.; Zastrow, U.

1997-07-01T23:59:59.000Z

383

Silicon avalanche photodiode operation and lifetime analysis for small satellites  

E-Print Network [OSTI]

Silicon avalanche photodiodes (APDs) are sensitive to operating temperature fluctuations and are also susceptible to radiation flux expected in satellite-based quantum experiments. We introduce a low power voltage adjusting mechanism to overcome the effects of in-orbit temperature fluctuations. We also present data on the performance of Si APDs after irradiation (gamma-ray and proton beam). Combined with an analysis of expected orbital irradiation, we propose that a Si APD in a 400 km equatorial orbit may operate beyond the lifetime of the satellite.

Tan, Yue Chuan; Cheng, Cliff; Ling, Alexander

2013-01-01T23:59:59.000Z

384

Silicon avalanche photodiode operation and lifetime analysis for small satellites  

E-Print Network [OSTI]

Silicon avalanche photodiodes (APDs) are sensitive to operating temperature fluctuations and are also susceptible to radiation flux expected in satellite-based quantum experiments. We introduce a low power voltage adjusting mechanism to overcome the effects of in-orbit temperature fluctuations. We also present data on the performance of Si APDs after irradiation (gamma-ray and proton beam). Combined with an analysis of expected orbital irradiation, we propose that a Si APD in a 400 km equatorial orbit may operate beyond the lifetime of the satellite.

Yue Chuan Tan; Rakhitha Chandrasekara; Cliff Cheng; Alexander Ling

2013-06-28T23:59:59.000Z

385

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

386

Plasmonic Back Structures Designed for Efficiency Enhancement of Thin Film Solar Cells  

Science Journals Connector (OSTI)

Metallic back structures with one-dimensional periodic nanoridges attached to thin-film amorphous silicon (a-Si) solar cell are proposed to enhance the cell efficiency in a wide...

Bai, Wenli; Gan, Qiaoqiang; Bartoli, Filbert; Song, Guofeng

387

Metal Nanoparticles Enhanced Optical Absorption in Thin Film Solar Cells  

Science Journals Connector (OSTI)

The plasmonic enhanced absorption for thin film solar cells with silver nanoparticles (NPs) deposited on top of the amorphous silicon film (a-Si:H) solar cells and embedded inside the...

Xie, Wanlu; Liu, Fang; Qu, Di; Xu, Qi; Huang, Yidong

388

Terra Solar Global Inc | Open Energy Information  

Open Energy Info (EERE)

Global Inc Jump to: navigation, search Name: Terra Solar Global Inc Place: New York, New York Zip: 10111-2000 Product: US-based manufacturer of amorphous silicon (a-Si) thin-film...

389

Photovoltaics in 1986: Routes to Low Cost  

Science Journals Connector (OSTI)

A cost based comparison of crystralline silicon (Xtal-Si) cells, amorphous siliccn (a-Si) cells and concentrators is undertaken. It is concluded that crystalline Si cells can lower significantly their cost by ...

Antonio Luque

1987-01-01T23:59:59.000Z

390

Graphene-Silicon Schottky Diodes  

Science Journals Connector (OSTI)

Graphene-Silicon Schottky Diodes ... We have fabricated graphene-silicon Schottky diodes by depositing mechanically exfoliated graphene on top of silicon substrates. ... The IV characteristics measured at 100, 300, and 400 K indicate that temperature strongly influences the ideality factor of graphenesilicon Schottky diodes. ...

Chun-Chung Chen; Mehmet Aykol; Chia-Chi Chang; A. F. J. Levi; Stephen B. Cronin

2011-04-25T23:59:59.000Z

391

Studies of a-Si:H growth mechanism, using deuterium, by rutherford recoil measurement  

SciTech Connect (OSTI)

a-Si:H were grown from silane and disilane by RF glow discharge. Deuterium (D) was used as a tracer in this investigation, in which four gas mixtures (SiH/sub 4/+D/sub 2/, SiD/sub 4/+H/sub 2/, Si/sub 2/H/sub 6/+D/sub 2/, and Si/sub 2/D/sub 6/+H/sub 2/) were employed. a-Si:H so produced were analyzed for H and D by Rutherford recoil measurement to determine whether these elements came from silanes or the dilution gas. When the RF power is low, much larger proportion of hydrogen atoms in silanes than in the dilution gas is found in a-Si:H. On the other hand, at high RF power, an excessive amount of D from the dilution gas, D/sub 2/, appears in a-Si:H.

Kuboi, O.; Aratani, M.; Hashimoto, M.; Hayashi, S.; Kohno, I.; Nagai, M.; Nozaki, T.; Yanokura, M.; Yatsurugi, Y.

1984-05-01T23:59:59.000Z

392

Study of microvoids in high-rate a-Si:H using positron annihilation  

SciTech Connect (OSTI)

In this paper, the authors have carried out the positron annihilation measurement on high-rate and low-rate a-Si:H thin films deposited by PECVD. By means of the slow positron beam Doppler-broadening technique, the depth profiles of microvoids in a-Si:H have been determined. They have also studied the vacancy-type defect in the surface region in high-rate grown a-Si:H, making comparison between high-rate and low-rate a-Si:H. By plotting S and W parameters in the (S, W) plane, they have shown that the vacancies in all of the high-rate and low-rate deposited intrinsic samples, and in differently doped low-rate samples are of the same nature.

Zou, X.; Webb, D.P.; Lin, S.H.; Lam, Y.W.; Chan, Y.C.; Hu, Y.F.; Beling, C.D.; Fung, S.

1997-07-01T23:59:59.000Z

393

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

SciTech Connect (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

394

a-Si:H films deposited by DC-MASD technique at high substrate temperature  

SciTech Connect (OSTI)

A dc-magnetron assisted silane decomposition technique has been tested for deposition of undoped a-Si:H at substrate temperature, T{sub s} = 300--400 C. In the optimized condition device-quality a-Si:H films were deposited independently of T{sub s}. A low hydrogen content C{sub H} (up to 2 at.%) and microstructure variations are characteristic of the MASD films.

Golikova, O.A.; Kuznetsov, A.N.; Kudojarova, V.Kh.; Kazanin, M.M.; Kosarev, A.I. [A.F. Ioffe Physico-Technical Inst., St. Petersburg (Russian Federation)

1996-12-31T23:59:59.000Z

395

Amorphous Molecular Organic Solids for Gas Adsorption. | EMSL  

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

and JL Atwood.2009."Amorphous Molecular Organic Solids for Gas Adsorption."Angewandte Chemie International Edition 48(30):5492 5495. Authors: J Tian PK Thallapally SJ Dalgarno...

396

Electron-Stimulated Production of Molecular Oxygen in Amorphous...  

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

Precursor Transport Through the Hydrogen Electron-Stimulated Production of Molecular Oxygen in Amorphous Solid Water on Pt(111): Precursor Transport Through the Hydrogen...

397

Probing the Interaction of Amorphous Solid Water on a Hydrophobic...  

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

Surface: Dewetting and Crystallization Kinetics of ASW on Abstract: Desorption of carbon tetrachloride from beneath an amorphous solid water (ASW) overlayer is explored...

398

Analysis of a-Si:H/TCO contact resistance for the Si heterojunction back-contact solar cell  

E-Print Network [OSTI]

Analysis of a-Si:H/TCO contact resistance for the Si heterojunction back-contact solar cell Seung- circuit voltage (Voc) and the conversion efficiency of the Si solar cell. Recently, a-Si:H heterojunction (heterojunction with intrinsic thin layer) cell [1] even with practical-sized Czochralski-grown (CZ) wafer. The a-Si:H

Park, Byungwoo

399

Behavior of Si and C atoms in ion amorphized SiC. | EMSL  

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

Si and C atoms in ion amorphized SiC. Behavior of Si and C atoms in ion amorphized SiC. Abstract: Single crystal 6H-SiC wafers were fully amorphized at room temperature or 200 K...

400

Annealing Simulations of Nano-Sized Amorphous Structures in SiC...  

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

Simulations of Nano-Sized Amorphous Structures in SiC. Annealing Simulations of Nano-Sized Amorphous Structures in SiC. Abstract: A two-dimensional model of a nano-sized amorphous...

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

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

SciTech Connect (OSTI)

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

402

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

SciTech Connect (OSTI)

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

403

Application of a-Si:H radiation detectors in medical imaging  

SciTech Connect (OSTI)

Monte Carlo simulations of a proposed a-Si:H-based current-integrating gamma camera were performed. The analysis showed that the intrinsic resolution of such a camera was 1 {approximately} 2.5 mm, which is somewhat better than that of a conventional gamma camera, and that the greater blurring, due to the detection of scattered {gamma}-rays, could be reduced considerably by image restoration techniques. This proposed gamma camera would be useful for imaging shallow organs such as the thyroid. Prototype charge-storage a-Si:H pixel detectors for such a camera were designed, constructed and tested. The detectors could store signal charge as long as 5 min at {minus}26C. The thermal generation current in reverse biased a-Si:H p-i-n photodetectors was investigated, and the Poole-Frenkel effect was found to be the most significant source of the thermal generation current. Based on the Poole-Frenkel effect, voltage- and time-dependent thermal generation current was modeled. Using the model, the operating conditions of the proposed a-Si:H gamma camera, such as the operating temperature, the operating bias and the {gamma}-scan period, could be predicted. The transient photoconductive gain mechanism in various a-Si:H devices was investigated for applications in digital radiography. Using the a-Si:H photoconductors in n-i-n configuration in pixel arrays, enhancement in signal collection (more than 200 times higher signal level) can be achieved in digital radiography, compared to the ordinary p-i-n type a-Si:H x-ray imaging arrays.

Lee, Hyoung-Koo

1995-06-01T23:59:59.000Z

404

Ultratough, Thermally Stable Polycrystalline Diamond/Silicon...  

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

Ultratough, Thermally Stable Polycrystalline DiamondSilicon Carbide Nanocomposites for Drill Bits Ultratough, Thermally Stable Polycrystalline DiamondSilicon Carbide...

405

Amorphous hafnium-indium-zinc oxide semiconductor thin film transistors  

Science Journals Connector (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

406

Amorphe ferromagnetische werkstoffe - magnetische grundlagen, eigenschaften und anwendungen  

Science Journals Connector (OSTI)

Zusammenfassung Nach einem berblick ber die magnetischen Grundkonstanten und die erzielten Eigenschaftswerte ferromagnetischer amorpher Legierungen werden technische Anwendungsmglichkeiten behandelt. After a survey is given of the fundamental magnetic aspects and the properties attained with ferromagnetic amorphous alloys, different fields of applications are discussed.

H.-R Hilzinger; A Mager; H Warlimont

1978-01-01T23:59:59.000Z

407

Pentagonal puckering in a sheet of amorphous graphene  

E-Print Network [OSTI]

Pentagonal puckering in a sheet of amorphous graphene Y. Li 1 , F. Inam 2 , Avishek Kumar 3 , M. F 2011 Published online 13 July 2011 Keywords amorphous graphene, density functional theory, fullerenes Ordered graphene has been extensively studied. In this paper, we undertake a density functional study

Thorpe, Michael

408

Glutamate Surface Speciation on Amorphous Titanium Dioxide and  

E-Print Network [OSTI]

Glutamate Surface Speciation on Amorphous Titanium Dioxide and Hydrous Ferric Oxide D I M I T R I (HFO) and titanium dioxide exhibit similar strong attachment of many adsorbates including biomolecules on amorphous titanium dioxide. The results indicate that glutamate adsorbs on HFO as a deprotonated divalent

Sverjensky, Dimitri A.

409

Optical properties of nanostructured silicon-rich silicon dioxide  

E-Print Network [OSTI]

We have conducted a study of the optical properties of sputtered silicon-rich silicon dioxide (SRO) thin films with specific application for the fabrication of erbium-doped waveguide amplifiers and lasers, polarization ...

Stolfi, Michael Anthony

2006-01-01T23:59:59.000Z

410

E-Print Network 3.0 - al-based amorphous matrix Sample Search...  

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

(2000) 238250 www.elsevier.comlocatejallcom Summary: microscopic investigations of the formation of eutectic alloys in the systems: amorphous Siparticle Au... , amorphous Si...

411

E-Print Network 3.0 - amorphous si films Sample Search Results  

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

jallcom Summary: microscopic investigations of the formation of eutectic alloys in the systems: amorphous Siparticle Au... , amorphous Siparticle Al showed that the formation...

412

Exclusively Thermal Donor-doped Cz Wafers for Silicon Heterojunction Solar Cell Technology  

Science Journals Connector (OSTI)

Abstract In this paper, a first evaluation of the compatibility between thermal donor-doped Czochralski silicon and the hydrogenated amorphous Silicon/crystalline Silicon heterojunction technology, is presented. The wafers resistivity was adjusted thanks to the controlled thermal donors generation through 450C anneals of calculated durations, following a model detailed in this paper. Minority carrier lifetimes higher than 2 milliseconds, matching the requirements of the heterojunction technology used, were demonstrated. The solar cells were manufactured and efficiencies comparable to cells based on high quality Float-Zone substrates were obtained. The stability of the solar cells performances under illumination and temperature was also assessed, and revealed no degradation of the bulk quality even after prolonged illumination.

Frdric Jay; Jordi Veirman; Nora Najid; Delfina Muoz; Sbastien Dubois; Anis Jouini

2014-01-01T23:59:59.000Z

413

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)

414

Floating Silicon Method  

SciTech Connect (OSTI)

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

Kellerman, Peter

2013-12-21T23:59:59.000Z

415

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).

Medernach, John W. (Albuquerque, NM)

1994-01-01T23:59:59.000Z

416

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

417

Tailored magnetic anisotropy in an amorphous trilayer  

SciTech Connect (OSTI)

An amorphous Co{sub 68}Fe{sub 24}Zr{sub 8}(3 nm)/Al{sub 70}Zr{sub 30}(3 nm)/Co{sub 68}Fe{sub 24}Zr{sub 8}(3 nm) trilayer system has been investigated using in-plane and out-of-plane angular dependent ferromagnetic resonance at different frequencies. The in-plane magnetic anisotropy is uniaxial, retaining its value of (2.9 {+-} 0.1) x 10{sup 3} J/m{sup 3} for each magnetic layer, whereas its direction was tailored independently in an arbitrary manner by applying an external magnetic field during the film deposition. The perpendicular anisotropy constant, supposed to reflect the interface quality, is nearly identical for both layers. Furthermore, the magnetic layers act independently upon each other due to the absence of interlayer coupling.

Fu Yu [Department of Physics, Southeast University, 211189 Nanjing (China); Fakultaet fuer Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), Universitaet Duisburg-Essen, 47048 Duisburg (Germany); Barsukov, I.; Spasova, M.; Lindner, J.; Meckenstock, R.; Farle, M. [Fakultaet fuer Physik and Center for Nanointegration Duisburg-Essen (CeNIDE), Universitaet Duisburg-Essen, 47048 Duisburg (Germany); Raanaei, H. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden); Department of Physics, Persian Gulf University, Bushehr 75168 (Iran, Islamic Republic of); Hjoervarsson, B. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden)

2011-06-01T23:59:59.000Z

418

E-Print Network 3.0 - amorphous silicon detector Sample Search...  

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

Jacobs University Bremen Collection: Engineering ; Materials Science 26 Mechanics of thin-film transistors and solar cells on flexible substrates Helena Gleskova* Summary: be...

419

Introduction Physics and Technology of Amorphous-Crystalline Heterostructure Silicon Solar Cells  

Science Journals Connector (OSTI)

Although photovoltaic solar energy technology (PV) is not the sole answer to the challenges posed by the ever-growing energy consumption worldwide, this renewable energy option can make an important contributi...

Wilfried van Sark; Lars Korte

2012-01-01T23:59:59.000Z

420

E-Print Network 3.0 - amorphous silicon microdisk Sample Search...  

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

of a microdisk. 2000 American Institute of Physics. S0003-6951 00 02824-2 Optoelectronic devices based Source: Cao, Hui - Department of Applied Physics, Yale University...

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

E-Print Network 3.0 - amorphous silicon pv Sample Search Results  

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

OF ... Source: Ecole Polytechnique, Centre de mathmatiques Collection: Mathematics 26 Solar Photovoltaics development -Status and perspectives Summary: in photovoltaic materi-...

422

Hydrogen incorporation during deposition of a-Si:H from an intense source of SiH{sub 3}  

SciTech Connect (OSTI)

The incorporation of hydrogen during the fast deposition of a-Si:H from an expanding thermal arc is investigated by means of isotope labeling of the precursor gases silane and hydrogen. It is found that hydrogen in a-Si:H originates dominantly from the silyl radical. A small fraction of the hydrogen in a-Si:H is due to exchange reaction of atomic hydrogen in the plasma with hydrogen chemisorbed on the surface during growth.

Van de Sanden, M.C.M.; Severens, R.J.; Kessels, W.M.M.; Van de Pas, F.; Van Ijzendoorn, L.; Schram, D.C.

1997-07-01T23:59:59.000Z

423

Investigations of ultra-thin single layer a-Si:H films  

SciTech Connect (OSTI)

Measurements are presented as direct evidence of tail states in ultra-thin a-Si:H single layer films. Including tail states in computer simulations completely removes the staircase structure in the differential optical spectra, previously associated with the quantum confinement of carriers.

Koehler, S.A.

1997-07-01T23:59:59.000Z

424

Theory and simulation of amorphous organic electronic devices  

E-Print Network [OSTI]

The electronic properties of amorphous organic thin films are of great interest due to their application in devices such as light emitting devices, solar cells, photodetectors, and lasers. Compared to conventional inorganic ...

Madigan, Conor (Conor Francis), 1978-

2006-01-01T23:59:59.000Z

425

Amorphous Iron(III) OxideA Review  

Science Journals Connector (OSTI)

The syntheses of amorphous Fe2O3 nanoparticles of varying size and morphology, their magnetic properties, crystallization mechanism, and applications are reviewed herein. The synthetic routes are classified according to the nature of the sample (powders, ...

Libor Machala; Radek Zboril; Aharon Gedanken

2007-04-03T23:59:59.000Z

426

Atomistic simulations of radiation damage in amorphous metal alloys  

E-Print Network [OSTI]

While numerous fundamental studies have characterized the atomic-level radiation response mechanisms in irradiated crystalline alloys, comparatively little is known regarding the mechanisms of radiation damage in amorphous ...

Baumer, Richard E. (Richard Edward)

2013-01-01T23:59:59.000Z

427

Electrodeposition of amorphous matrix Ni-W/Wp̳ composites  

E-Print Network [OSTI]

An amorphous Ni-W alloy matrix was incorporated with W particulate through two types of electrodeposition. The plating bath for the electrodeposition contained nickel sulfate, sodium tungstate, sodium citrate, ammonium ...

Jenket, Donald R. (Donald Robert)

2005-01-01T23:59:59.000Z

428

Hall-Effect in Amorphous La1-Xgax Foils  

E-Print Network [OSTI]

, but to date no calculations exist which predict this for liquid or amorphous La. The temperature dependence is also anomalous but so is that of cry- stalline La. More precise measurements of RII for this system are desirable. We are considering..., but to date no calculations exist which predict this for liquid or amorphous La. The temperature dependence is also anomalous but so is that of cry- stalline La. More precise measurements of RII for this system are desirable. We are considering...

COLTER, PC; Adair, Thomas W.; Naugle, Donald G.

1979-01-01T23:59:59.000Z

429

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

SciTech Connect (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

430

Variable-amplitude oscillatory shear response of amorphous materials  

E-Print Network [OSTI]

Variable-amplitude oscillatory shear tests are emerging as powerful tools to investigate and quantify the nonlinear rheology of amorphous solids, complex fluids and biological materials. Quite a few recent experimental and atomistic simulation studies demonstrated that at low shear amplitudes, an amorphous solid settles into an amplitude- and initial conditions-dependent dissipative limit cycle, in which back-and-forth localized particle rearrangements periodically bring the system to the same state. At sufficiently large shear amplitudes, the amorphous system loses memory of the initial conditions, exhibits chaotic particle motions accompanied by diffusive behavior and settles into a stochastic steady-state. The two regimes are separated by a transition amplitude, possibly characterized by some critical-like features. Here we argue that these observations support some of the physical assumptions embodied in the nonequilibrium thermodynamic, internal-variables based, Shear-Transformation-Zone model of amorphous visco-plasticity; most notably that "flow defects" in amorphous solids are characterized by internal states between which they can make transitions, and that structural evolution is driven by dissipation associated with plastic deformation. We present a rather extensive theoretical analysis of the thermodynamic Shear-Transformation-Zone model for a variable-amplitude oscillatory shear protocol, highlighting its success in accounting for various experimental and simulational observations, as well as its limitations. Our results offer a continuum-level theoretical framework for interpreting the variable-amplitude oscillatory shear response of amorphous solids and may promote additional developments.

Nathan Perchikov; Eran Bouchbinder

2014-04-13T23:59:59.000Z

431

Bagdad Plant Raymond J. Polinski 585 Silicon Drive General Manager  

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

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

432

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

433

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

434

A SiC-Based Converter as a Utility Interface for a Battery System , Leon M. Tolbert1,2  

E-Print Network [OSTI]

A SiC-Based Converter as a Utility Interface for a Battery System Hui Zhang1 , Leon M. Tolbert1 of a SiC-based converter as a utility interface in battery systems. System design and modelingC-based converter. (2) With the same thermal limit, large savings in system weight and volume combined with a high

Tolbert, Leon M.

435

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

436

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

437

Fabrication and properties of microporous silicon  

E-Print Network [OSTI]

Microporous silicon layers were fabricated by electrochemical etching of single crystalline silicon wafers in HF-ethanol solutions. The pore properties of porous silicon were examined by physical adsorption of nitrogen and the relationship between...

Shao, Jianzhong

1994-01-01T23:59:59.000Z

438

JOURNAL DE PHYSIQUE CoZZoque C4, suppZdment au nOIO, Tome 42, octobre 1981 page C4-463  

E-Print Network [OSTI]

.- The possibility of low-cost thin film photovoltaic cells using amorphous silicon (a-Si) based alloys has generated EFFICIENCY, LARGE-AREA PHOTOVOLTAIC DEVICES USING AMORPHOUS Si:F:H ALLOY A. Madan, W. Czubatyj, J. Yang, J, U. S.A. Abstract.- Overall conversion efficiency of 6.6% has been obtained for a photovoltaic device

Paris-Sud XI, Université de

439

Silicon Photonic Components and Networks  

Science Journals Connector (OSTI)

Significant progress in silicon photonics has led to flattop filters, polarization independence, low power modulators and switches, and low dark current germanium detectors. Future...

Watts, Michael

440

Heterojunction Silicon Microwire Solar Cells  

Science Journals Connector (OSTI)

Heterojunction Silicon Microwire Solar Cells ... Center for Advanced Photovoltaic Devices and Systems, University of Waterloo, 200 University Ave W, Waterloo, Ontario N2L 3G1, Canada ...

Majid Gharghi; Ehsanollah Fathi; Boubacar Kante; Siva Sivoththaman; Xiang Zhang

2012-11-21T23:59:59.000Z

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.


441

Molecular dynamics investigations of boron doping in a-Si:H  

SciTech Connect (OSTI)

The rather low doping efficiency of B in a-Si:H is almost always explained by the argument that almost all of the B is incorporated into three-fold coordinated sites and that B is inert or non-doping in this configuration. Using ab initio molecular dynamics, the authors have studied the energetics and doping (electronic structure) consequences of B incorporation into a-Si:H both with and without H passivation. Their results suggest that the conventional view is in error and that the low doping efficiency is primarily due to H passivation. These results are consistent with the low doping efficiency of B as well as NMR studies on the large electric field gradients experienced by the B atoms and on NMR double resonance studies of B-H neighboring distances.

Fedders, P.A.; Drabold, D.A.

1997-07-01T23:59:59.000Z

442

Low temperature production of large-grain polycrystalline semiconductors  

DOE Patents [OSTI]

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

443

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

SciTech Connect (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

444

Damage of amorphous carbon induced by soft x-ray femtosecond pulses above and below the critical angle  

SciTech Connect (OSTI)

We present results of damage studies conducted at the Free Electron LASer in Hamburg (FLASH) facility with 13.5 nm (91.8 eV) and 7 nm (177.1 eV) radiations. The laser beam was focused on a sample of 890-nm-thick amorphous carbon coated on a silicon wafer mimicking a x-ray mirror. The fluence threshold for graphitization was determined for different grazing angles above and below the critical angle. The observed angular dependence of F{sub th} is explained by the variation in absorption depth and reflectivity. Moreover, the absorbed local dose needed for the phase transition leading to graphitization is shown to vary with the radiation wavelength.

Chalupsky, J.; Hajkova, V.; Burian, T.; Juha, L.; Vysin, L. [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Altapova, V.; Sinn, H.; Tschentscher, Th.; Gaudin, J. [European XFEL, DESY, Notkestr., 85 D-22607 Hamburg (Germany); Gleeson, A. J. [CCRLC Daresbury Laboratory, Warrington, Cheshire WA4 4AD (United Kingdom); Jurek, M.; Sobierajski, R. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, PL-02-668 Warsaw (Poland); Stoermer, M. [GKSS-Forschungszentrum Geesthacht GmbH, Max-Planck-Strasse, 1 21502 Geesthach (Germany); Tiedtke, K.; Toleikis, S.; Wabnitz, H. [HASYLAB/DESY, Notkestr., 85 D-22607 Hamburg (Germany)

2009-07-20T23:59:59.000Z

445

Initial growth on microcrystalline silicon on atomically flat hetero-substrate  

SciTech Connect (OSTI)

Initial growth of microcrystalline silicon ({micro}c-Si:H) deposited on an atomically flat GaAs (001) wafer using a RF glow-discharge decomposition of hydrogen diluted monosilane gas mixture has been studied by means of atomic force microscope (AFM), Auger electron spectroscopy (AES), and cross-sectional transmission electron microscopy (XTEM). It is shown that the initial growth of {micro}c-Si:H deposited at a substrate temperature of 50--250 C consists of four successive stages, i.e., (1) a layer-by-layer growth of a-Si:H up to d {approximately}5 {angstrom}, (2) island formation of a-Si:H, (3) the coalescence of the islands and the nucleation of microcrystalline at d{approximately}10{approximately}40 {angstrom} depending on the growth temperature, and (4) a rapid roughening with microcrystalline growth.

Saitoh, K.; Kondo, M.; Matsuda, A.

1997-07-01T23:59:59.000Z

446

Effect of temperature and stress on plastic deformation in monocrystalline silicon induced by scratching  

Science Journals Connector (OSTI)

Dry air coolant and liquid nitrogen were applied respectively to study the effect of temperature and stress on plastic deformation in scratching monocrystalline silicon. Phases generated in surfacedeformation were characterized by means of the transmission electron microscopy. It was shown that the size of the amorphous transformation zone and the depth of slip penetration in sample subsurface were mainly dependent on the stress field applied. The influence of the temperature variation to ?196?C was surprisingly small and the low temperature did not suppress the phase transformation and dislocation activity.

I. Zarudi; T. Nguyen; L. C. Zhang

2005-01-01T23:59:59.000Z

447

Stress-induced patterns in ion-irradiated Silicon: a model based on anisotropic plastic flow  

E-Print Network [OSTI]

We present a model for the effect of stress on thin amorphous films that develop atop ion-irradiated silicon, based on the mechanism of ion-induced anisotropic plastic flow. Using only parameters directly measured or known to high accuracy, the model exhibits remarkably good agreement with the wavelengths of experimentally-observed patterns, and agrees qualitatively with limited data on ripple propagation speed. The predictions of the model are discussed in the context of other mechanisms recently theorized to explain the wavelengths, including extensive comparison with an alternate model of stress.

Scott A. Norris

2012-07-24T23:59:59.000Z

448

Infrared laser-based monitoring of the silane dissociation during deposition of silicon thin films  

SciTech Connect (OSTI)

The silane dissociation efficiency, or depletion fraction, is an important plasma parameter by means of which the film growth rate and the amorphous-to-microcrystalline silicon transition regime can be monitored in situ. In this letter we implement a homebuilt quantum cascade laser-based absorption spectrometer to measure the silane dissociation efficiency in an industrial plasma-enhanced chemical vapor deposition system. This infrared laser-based diagnostic technique is compact, sensitive, and nonintrusive. Its resolution is good enough to resolve Doppler-broadened rotovibrational absorption lines of silane. The latter feature various absorption strengths, thereby enabling depletion measurements over a wide range of process conditions.

Bartlome, R.; Feltrin, A.; Ballif, C. [Ecole Polytechnique Federale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin Film Electronics Laboratory, Rue A.-L. Breguet 2, 2000 Neuchatel (Switzerland)

2009-05-18T23:59:59.000Z

449

Effect of grain size and hydrogen passivation on the electrical properties of nanocrystalline silicon films  

Science Journals Connector (OSTI)

The properties of mixed-phase (nanocrystalline/amorphous) silicon layers produced by reactive RF-sputtering are described. The chemical composition and nanostructure (i.e., Nanocrystal (NC) size and volume fraction) of the films were studied by Rutherford Backscattering Spectroscopy (RBS) and micro-Raman spectroscopy, respectively. Samples with different fractions of the nanocrystalline phase and NC mean size were produced by changing the deposition parameters, without post-growth annealing. The electrical conductivity of the films, measured as function of temperature, is discussed in relation to their nanostructure.

M.F. Cerqueira; T.V. Semikina; N.V. Baidus; E. Alves

2010-01-01T23:59:59.000Z

450

Nanoscale Engineering Of Radiation Tolerant Silicon Carbide....  

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

Engineering Of Radiation Tolerant Silicon Carbide. Nanoscale Engineering Of Radiation Tolerant Silicon Carbide. Abstract: Radiation tolerance is determined by how effectively the...

451

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  

SciTech Connect (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

452

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

SciTech Connect (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

453

Recent developments in silicon calorimetry  

SciTech Connect (OSTI)

We present a survey of some of the recent calorimeter applications of silicon detectors. The numerous attractive features of silicon detectors are summarized, with an emphasis on those aspects important to calorimetry. Several of the uses of this technology are summarized and referenced. We consider applications for electromagnetic calorimetry, hadronic calorimetry, and proposals for the SSC.

Brau, J.E.

1990-11-01T23:59:59.000Z

454

Silicon Thin-Film Formation by Direct Photochemical Decomposition of Disilane  

Science Journals Connector (OSTI)

Silicon thin-films have been deposited by the direct photolysis of disilane at a substrate temperature below 300C. The growth rate depends on irradiation intensity of a low pressure mercury-lamp, and a typical rate of 15 /min has been obtained under ~0.08 watts/cm2 illumination, regardless of substrate temperature. The deposited films are composed of an amorphous network containing bonded-hydrogen in the range 69 at.%. The bonding configurations of SiH groups varied from silicon dihydride to monohydride with increasing substrate temperature, and correspondingly the dark conductivity decreased from 10-7 to 10-11 ?-1cm-1. A broad photoluminescence peak at 1.4 eV was observed for a specimen grown at 200C.

Yasuyoshi Mishima; Masataka Hirose; Yukio Osaka; Kunihiro Nagamine; Yoshinori Ashida; Nobuhisa Kitagawa; Kazuyoshi Isogaya

1983-01-01T23:59:59.000Z

455

Lasing modes in polycrystalline and amorphous photonic structures  

SciTech Connect (OSTI)

We systematically studied the lasing characteristics in photonic polycrystalline and amorphous structures. 2D arrays of air holes were fabricated in a GaAs membrane. InAs quantum dots embedded in the membrane provide gain for lasing under optical pumping. The lasing modes are spatially localized, and blue shift as the structural order becomes short ranged. Our three-dimensional numerical simulations reveal that the out-of-plane leakage of the lasing mode dominates over the in-plane leakage. The lasing modes in a photonic polycrystalline move away from the center frequency of the photonic band gap to reduce the out-of-plane leakage. In a photonic amorphous structure, the short-range order improves optical confinement and enhances the quality factor of resonances. Understanding the behavior of photonic polycrystalline laser and amorphous laser opens the possibility of controlling lasing characteristic by varying the degree of structural order.

Yang, Jin-Kyu [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Optical Engineering, Kongju National University, Kongju 314-701 (Korea, Republic of); Noh, Heeso; Liew, Seng Fatt; Rooks, Michael J. [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Solomon, Glenn S. [Joint Quantum Institute, NIST and University of Maryland, Gaithersburg, Maryland 20899 (United States); Cao Hui [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520 (United States)

2011-09-15T23:59:59.000Z

456

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

SciTech Connect (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

457

Stability of single and tandem junction a-Si:H solar cells grown using the ECR process  

SciTech Connect (OSTI)

The authors report on the fabrication and stability tests of single junction a-Si:H, and tandem junction a-Si:H/A-Si:H solar cells using the ECR process under high hydrogen dilution (H-ECR process). They show that devices with high fill factors can be made using the H-ECR process. They also report on the stability studies of the solar cells under 1 and 2-sun illumination conditions. The solar cells show very little degradation even after 500 hours of illumination under 2 x sunlight illumination.

Dalal, V.L.; Maxson, T.; Girvan, R.; Haroon, S.

1997-07-01T23:59:59.000Z

458

Amorphous Alloy Membranes for High Temperature Hydrogen Separation  

SciTech Connect (OSTI)

At the beginning of this project, thin film amorphous alloy membranes were considered a nascent but promising new technology for industrial-scale hydrogen gas separations from coal- derived syngas. This project used a combination of theoretical modeling, advanced physical vapor deposition fabricating, and laboratory and gasifier testing to develop amorphous alloy membranes that had the potential to meet Department of Energy (DOE) targets in the testing strategies outlined in the NETL Membrane Test Protocol. The project is complete with Southwest Research Institute (SwRI), Georgia Institute of Technology (GT), and Western Research Institute (WRI) having all operated independently and concurrently. GT studied the hydrogen transport properties of several amorphous alloys and found that ZrCu and ZrCuTi were the most promising candidates. GT also evaluated the hydrogen transport properties of V, Nb and Ta membranes coated with different transition-metal carbides (TMCs) (TM = Ti, Hf, Zr) catalytic layers by employing first-principles calculations together with statistical mechanics methods and determined that TiC was the most promising material to provide catalytic hydrogen dissociation. SwRI developed magnetron coating techniques to deposit a range of amorphous alloys onto both porous discs and tubular substrates. Unfortunately none of the amorphous alloys could be deposited without pinhole defects that undermined the selectivity of the membranes. WRI tested the thermal properties of the ZrCu and ZrNi alloys and found that under reducing environments the upper temperature limit of operation without recrystallization is ~250 C. There were four publications generated from this project with two additional manuscripts in progress and six presentations were made at national and international technical conferences. The combination of the pinhole defects and the lack of high temperature stability make the theoretically identified most promising candidate amorphous alloys unsuitable for application as hydrogen separation membranes in coal fire systems.

Coulter, K

2013-09-30T23:59:59.000Z

459

Cordierite silicon nitride filters  

SciTech Connect (OSTI)

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

460

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

SciTech Connect (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

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.


461

Electrochemical investigations on amorphous Fe-base alloys for alkaline water electrolysis  

Science Journals Connector (OSTI)

Abstract In this work different amorphous melt-spun Fe-alloys (Fe82B18, Fe80Si10B10, Fe60Co20Si10B10) were investigated as cathode materials for the alkaline electrolysis of water. In particular, the influence of cobalt as well as the metalloids boron and silicon on the activity for the hydrogen evolution reaction (HER) was studied in 1M KOH at 298K using cyclic voltammetric, galvanostatic and polarization techniques. The electrocatalytic activity was evaluated in the view of the overpotential. It was found that cyclic voltammetric techniques can be used to activate the melt-spun Fe-alloys strongly. Different cyclic voltammetric activation procedures are discussed and the influence of the sweep rate and the potential window on the HER activity was elucidated. The experimental data indicate that the addition of metalloids and, most importantly, of cobalt improves the HER activity of the materials. Thus, the overpotential can be reduced by 200mV compared to polycrystalline Ni.

Christian Immanuel Mller; Thomas Rauscher; Andreas Schmidt; Thomas Schubert; Thomas Weigrber; Bernd Kieback; Lars Rntzsch

2014-01-01T23:59:59.000Z

462

A transparent ultraviolet triggered amorphous selenium p-n junction  

SciTech Connect (OSTI)

This paper will introduce a semitransparent amorphous selenium (a-Se) film exhibiting photovoltaic effects under ultraviolet light created through a simple and inexpensive method. We found that chlorine can be doped into a-Se through electrolysis of saturated salt water, and converts the weak p-type material into an n-type material. Furthermore, we found that a p-n diode fabricated through this process has shown an open circuit voltage of 0.35 V toward ultraviolet illumination. Our results suggest the possibility of doping control depending on the electric current during electrolysis and the possibility of developing a simple doping method for amorphous photoconductors.

Saito, Ichitaro; Soga, Kenichi; Overend, Mauro; Amaratunga, Gehan A. J. [Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Miyazaki, Wataru; Onishi, Masanori; Masuzawa, Tomoaki; Okano, Ken [Department of Physics, International Christian University, 3-10-2 Osawa Mitaka, Tokyo 181-8585 (Japan); Kudo, Yuki [Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Yamada, Takatoshi [Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Koh, Angel; Chua, Daniel [Department of Materials Science and Engineering, National University of Singapore, 21 Lower Kent Ridge Road, Singapore 119077 (Singapore); Aono, Masami [Department of Materials Science and Engineering, National Defense Academy, 1-10-20 Hashirimizu Yokosuka, Kanagawa 239-8686 (Japan)

2011-04-11T23:59:59.000Z

463

Chemical Bonding In Amorphous Si Coated-carbon Nanotube As Anodes...  

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

Bonding In Amorphous Si Coated-carbon Nanotube As Anodes For Li ion Batteries: A XANES Study. Chemical Bonding In Amorphous Si Coated-carbon Nanotube As Anodes For Li ion...

464

E-Print Network 3.0 - amorphous ferromagnetic semiconductor Sample...  

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

ORDERING AND MAGNETIZATION IN AMORPHOUS Fe-Ge FILMS 0.MASSENET, H. DAVER, Phase Transition Group, Centre... amorphes d'alliages Fe-Ge dont la composition varie de 0 B 75 at. %...

465

E-Print Network 3.0 - as-doped buried amorphous Sample Search...  

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

Amorphous Si A.J. Dent, G. Derst, G.N. Greaves, S. Kalbitzer* and C... Heidelberg, Germany Abstract. Our previous work has concentrated on the recrystallisation of amorphous...

466

Temperature response of 13C atoms in amorphized 6H-SiC. | EMSL  

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

Temperature response of 13C atoms in amorphized 6H-SiC. Temperature response of 13C atoms in amorphized 6H-SiC. Abstract: Implantation of 13C2+ ions was employed to produce a...

467

The Breaking of the Efficiency-Stability-Production Barrier In Amorphous Photovoltaics  

Science Journals Connector (OSTI)

There are three key issues that challenge amorphous photovoltaics, namely, efficiency, stability, and production. ... will review the current status of our amorphous photovoltaics at ECD in terms of these three.....

Stanford R. Ovshinsky; Jeffrey Yang

1991-01-01T23:59:59.000Z

468

E-Print Network 3.0 - amorphous bodies dover Sample Search Results  

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

in temperature dependent amorphization. The H2O-ice's phase was determined using the near infrared... ) band is strong while it is nearly absent in the amorphous spectrum...

469

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

DOE Patents [OSTI]

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

470

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

DOE Patents [OSTI]

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

471

Prospects for the use of amorphous semiconductors in solar energy conversion  

Science Journals Connector (OSTI)

... this article, we review some potential applications of amorphous Si in the field of solar energy ...energyconversion ...

J. I. B. Wilson; D. Weaire

1978-09-14T23:59:59.000Z

472

Process for forming retrograde profiles in silicon  

DOE Patents [OSTI]

A process is disclosed for forming retrograde and oscillatory profiles in crystalline and polycrystalline silicon. The process consisting of introducing an n- or p-type dopant into the silicon, or using prior doped silicon, then exposing the silicon to multiple pulses of a high-intensity laser or other appropriate energy source that melts the silicon for short time duration. Depending on the number of laser pulses directed at the silicon, retrograde profiles with peak/surface dopant concentrations which vary are produced. The laser treatment can be performed in air or in vacuum, with the silicon at room temperature or heated to a selected temperature.

Weiner, K.H.; Sigmon, T.W.

1996-10-15T23:59:59.000Z

473

Process for forming retrograde profiles in silicon  

DOE Patents [OSTI]

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

474

Low frequency noise behavior in a-Si:H Schottky barrier devices  

SciTech Connect (OSTI)

The authors present a systematic experimental study of low frequency noise behavior in Mo/a-Si:H Schottky diodes under reverse bias operation. The noise in the Schottky diode was found to increase with increasing reverse current and with an approximate 1/f behavior at low bias voltages, yielding a Hooge parameter in the range (2 to 3) {times} 10{sup {minus}4}. At high reverse voltages, due to electrical stressing and hence, bias-induced material instability, a significant deviation from the 1/f behavior was observed.

Aflatooni, K.; Nathan, A.; Hornsey, R. [Univ. of Waterloo, Ontario (Canada). Electrical and Computer Engineering

1996-12-31T23:59:59.000Z

475

Light-soaking effects on photoconductivity in a-Si:H thin films  

SciTech Connect (OSTI)

Metastable defects have been created by light exposure in thin films of a-Si:H. The samples have been characterized by Photothermal Deflection Spectroscopy, Electron Spin Resonance, dark- and photo-conductivity. The experimental results are consistent with numerical calculations with a recombination model involving band tails and one class of correlated dangling-bond states. The effects of light-soaking on the light intensity and defect density dependences of photoconductivity are reproduced by the calculations. The model allows to explain the experimental trends by changes in the electronic occupation of the gap states produced by light-induced defects.

Morgado, E.; Da Silva, M.R.; Henriques, R.T.

1997-07-01T23:59:59.000Z

476

Structure and electronic parameters of a-Si:H deposited by DC-MASD  

SciTech Connect (OSTI)

A systematic study of structure and electronic parameters of a-Si:H deposited by dc-magnetron assisted SiH{sub 4} decomposition (MASD) depending on substrate temperature, gas pressure, gas flow and grid mounting has been carried out. Correlation between the film microstructure, dangling bond density and electron mobility-life time product were established. The photoconductivity changes under light soaking were shown to be minimal when the films contained hydrogen in the (SiH{sub 2}){sub n} chains.

Golikova, O.A.; Kuznetsov, A.N.; Kudoyarova, V.K.; Kazanin, M.M.; Adriaenssens, G.J.; Herremans, H.

1997-07-01T23:59:59.000Z

477

The influence of the substrate temperature on the recombination processes in a-Si:H  

SciTech Connect (OSTI)

The authors have studied the four phototransport properties as a function of temperature in undoped a-Si:H films deposited with different substrate temperatures in the range 150--225 C. The analysis of the results indicates how T{sub s} determines the densities of the various defects. The general trend of decrease of both the density of dangling bonds and the Urbach energy is in agreement with the weak bond breaking model. However, they conclude that a slight modification of this model is required.

Lubianiker, Y.; Balberg, I.; Fonseca, L.; Weisz, S.Z.

1997-07-01T23:59:59.000Z

478

A forward bias method for lag correction of an a-Si flat panel detector  

SciTech Connect (OSTI)

Purpose: Digital a-Si flat panel (FP) x-ray detectors can exhibit detector lag, or residual signal, of several percent that can cause ghosting in projection images or severe shading artifacts, known as the radar artifact, in cone-beam computed tomography (CBCT) reconstructions. A major contributor to detector lag is believed to be defect states, or traps, in the a-Si layer of the FP. Software methods to characterize and correct for the detector lag exist, but they may make assumptions such as system linearity and time invariance, which may not be true. The purpose of this work is to investigate a new hardware based method to reduce lag in an a-Si FP and to evaluate its effectiveness at removing shading artifacts in CBCT reconstructions. The feasibility of a novel, partially hardware based solution is also examined. Methods: The proposed hardware solution for lag reduction requires only a minor change to the FP. For pulsed irradiation, the proposed method inserts a new operation step between the readout and data collection stages. During this new stage the photodiode is operated in a forward bias mode, which fills the defect states with charge. A Varian 4030CB panel was modified to allow for operation in the forward bias mode. The contrast of residual lag ghosts was measured for lag frames 2 and 100 after irradiation ceased for standard and forward bias modes. Detector step response, lag, SNR, modulation transfer function (MTF), and detective quantum efficiency (DQE) measurements were made with standard and forward bias firmware. CBCT data of pelvic and head phantoms were also collected. Results: Overall, the 2nd and 100th detector lag frame residual signals were reduced 70%-88% using the new method. SNR, MTF, and DQE measurements show a small decrease in collected signal and a small increase in noise. The forward bias hardware successfully reduced the radar artifact in the CBCT reconstruction of the pelvic and head phantoms by 48%-81%. Conclusions: Overall, the forward bias method has been found to greatly reduce detector lag ghosts in projection data and the radar artifact in CBCT reconstructions. The method is limited to improvements of the a-Si photodiode response only. A future hybrid mode may overcome any limitations of this method.

Starman, Jared; Tognina, Carlo; Partain, Larry; Fahrig, Rebecca [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States) and Department of Radiology, Stanford University, Stanford, California 94305 (United States); Varian Medical Systems, Palo Alto, California 94304 (United States); Department of Radiology, Stanford University, Stanford, California 94305 (United States)

2012-01-15T23:59:59.000Z

479

Dangling Bond Defects in a-Si,Ge Alloys: A Theoretical Study Using the Tight-Binding Method  

Science Journals Connector (OSTI)

This paper presents a theoretical study of Si and Ge atom dangling bond defects in a-Si,Ge alloys. We use a tight-binding Hamiltonian, and a structural model based on a cluster Bethe Lattice. The central clust...

S. Y. Lin; G. Lucovsky

1985-01-01T23:59:59.000Z

480

Roughening of a Si(100) surface induced by the adsorption of oxygen near the solid-oxide nucleation threshold  

Science Journals Connector (OSTI)

An investigation of the processes on a Si(100) surface interacting with oxygen near the solid-oxide nucleation threshold using x-ray photoelectron spectroscopy and atomic-force microscopy is described. The nuclea...

V. D. Borman; Yu. Yu. Lebedinskii

1998-07-01T23:59:59.000Z

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,
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We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys  

SciTech Connect (OSTI)

Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current dissertation involves an extensive set of experimental, analytical, and computational studies designed to increase the overall understanding of morphological selection, phase competition, and structural hierarchy that occurs under far-from equilibrium conditions. High pressure gas atomization and Cu-block melt-spinning are the two different rapid solidification techniques applied in this study. The research is mainly focused on Al-Si and Al-Sm alloy systems. Silicon and samarium produce different, yet favorable, systems for exploration when alloyed with aluminum under far-from equilibrium conditions. One of the main differences comes from the positions of their respective T{sub 0} curves, which makes Al-Si a good candidate for solubility extension while the plunging T{sub 0} line in Al-Sm promotes glass formation. The rapidly solidified gas-atomized Al-Si powders within a composition range of 15 to 50 wt% Si are examined using scanning and transmission electron microscopy. The non-equilibrium partitioning and morphological selection observed by examining powders at different size classes are described via a microstructure map. The interface velocities and the amount of undercooling present in the powders are estimated from measured eutectic spacings based on Jackson-Hunt (JH) and Trivedi-Magnin-Kurz (TMK) models, which permit a direct comparison of theoretical predictions. For an average particle size of 10 {micro}m with a Peclet number of {approx}0.2, JH and TMK deviate from each other. This deviation indicates an adiabatic type solidification path where heat of fusion is reabsorbed. It is interesting that this particle size range is also consistent with the appearance of a microcellular growth. While no glass formation is observed within this system, the smallest size powders appear to consist of a mixture of nanocrystalline Si and Al. Al-Sm alloys have been investigated within a composition range of 34 to 42 wt% Sm. Gas atomized powders of Al-Sm are investigated to explore the morphological and structural hierarchy that correlates with different degrees of departure from full equilibrium conditions. The resultant powders show a variety of structural selection with respect to amount of undercooling, with an amorphous structure appearing at the highest cooling rates. Because of the chaotic nature of gas atomization, Cu-block melt-spinning is used to produce a homogeneous amorphous structure. The as-quenched structure within Al-34 to 42 wt% Sm consists of nanocrystalline fcc-Al (on the order of 5 nm) embedded in an amorphous matrix. The nucleation density of fcc-Al after initial crystallization is on the order of 10{sup 22}-10{sup 23} m{sup -3}, which is 10{sup 5}-10{sup 6} orders of magnitude higher than what classical nucleation theory predicts. Detailed analysis of liquid and as-quenched structures using high energy synchrotron X-ray diffraction, high energy transmission electron microscopy, and atom probe tomography techniques revealed an Al-Sm network similar in appearance to a medium range order (MRO) structure. A model whereby these MRO clusters promote the observed high nucleation density of fcc-Al nanocrystals is proposed. The devitrification path was identified using high temperature, in-situ, high energy synchrotron X-ray diffraction techniques and the crystallization kinetics were described using an analytical Johnson-Mehl-Avrami (JMA) approach.

Kalay, Yunus Eren

2008-10-15T23:59:59.000Z

482

Phosphate and Organic Acids as Competing Sorbates on Amorphous Aluminum Oxide. (3791)  

E-Print Network [OSTI]

Phosphate and Organic Acids as Competing Sorbates on Amorphous Aluminum Oxide. (3791) Authors: K sorption of P to amorphous aluminum oxides. Alum initially decreases litter pH, so the stability of P was employed to investigate the adsorption of phosphate and oxalate, to synthetic amorphous aluminum hydroxide

Sparks, Donald L.

483

C. -AMORPHOUS METALLIC SYSTEMS. TEMPERATURE DEPENDENCE OF THE ELECTRICAL RESISTIVITY OF  

E-Print Network [OSTI]

C. - AMORPHOUS METALLIC SYSTEMS. TEMPERATURE DEPENDENCE OF THE ELECTRICAL RESISTIVITY OF AMORPHOUS of the electrical resistivity is explained with conduction electrons being scattered by p %. In a previous paper [I] it has been shown that the electrical resistivity of amorphous Ga, Sn and Pb alloys

Paris-Sud XI, Université de

484

Fabrication of porous silicon membranes  

E-Print Network [OSTI]

. In step 1, the surface of silicon is covered with fluorine ions. In step 2, when an electric field is applied across the interface, holes move towards the surface. In step 3, some of the holes are trapped at the surface, and they weaken the silicon...-silicon bonds. In step 4, thermal energy swings away the Si-F groups exposing the holes. In step 5, fluorine ions occupy the holes and release their charges. In the dissolution, Step 3 through Step 5 is repeated, and SiFz is removed from the reacting site...

Yue, Wing Kong

2012-06-07T23:59:59.000Z

485

In situ Study of the Formation of Silicide Phases in Amorphous Ni-Si Mixed Layers  

SciTech Connect (OSTI)

In this paper, we investigated Ni silicide phase formation when Si is added within an as deposited 50 nm Ni film. A series of 22 samples with a Si content varying from 0 to 50 at.% was prepared and systematically investigated with in situ x-ray diffraction. The inert oxide substrate was used to identify the phases which first crystallize in an amorphous Ni-Si mixture of a given concentration. The noncongruent silicides Ni{sub 3}Si and Ni{sub 3}Si{sub 2} are never observed to crystallize readily out of the mixture. A remarkable observation is the initial crystallization at low temperature of a hexagonal Ni-silicide, observed over a broad mixed layer composition [35-49%Si]; this hexagonal phase nucleates readily as a single phase [39-47%Si] or together with Ni{sub 2}Si [35-38%Si] or NiSi [49%Si]. This low-temperature phase is related to the high temperature {theta}-phase, but covers a wide composition range up to 47%Si. For the same Ni-Si films deposited on Si(100), the initial nucleation of the Ni(Si) mixture is similar as for the samples deposited on SiO{sub 2}, such that the complex sequence of metal-rich Ni-silicide phases typically observed during Ni/Si reactions is modified. For samples containing more than 21%Si, a simpler sequential phase formation was observed upon annealing. From pole figures, the phase formation sequence was observed to have a significant influence on the texture of the technologically relevant NiSi phase. For mixture composition ranging from 38% to 43%Si, the initial transient {theta}-phase appears extremely textured on Si(100). The observed transient appearance of a hexagonal phase is of importance in understanding the phase formation mechanisms in the Ni-Si system.

Van Bockstael, C.; Detavernier, C; Van Meirhaeghe, R; Jordan-Sweet, J; Lavoie, C

2009-01-01T23:59:59.000Z

486

Concentrator silicon cell research  

SciTech Connect (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

487

Silicone plesiotherapy molds  

SciTech Connect (OSTI)

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

488

Rheology of silicon carbide/vinyl ester nanocomposites  

E-Print Network [OSTI]

New York, 1999. SILICON CARBIDE/VINYL ESTER NANOCOMPOSITESRheology of Silicon Carbide/Vinyl Ester NanocompositesABSTRACT: Silicon carbide (SiC) nanoparticles with no

Yong, Virginia; Hahn, H. Thomas

2006-01-01T23:59:59.000Z

489

FORMATION OF A PHYSICALLY STABLE AMORPHOUS DRUG COMPLEX  

E-Print Network [OSTI]

ABSTRACT In this paper we explore the use of Neusilin, an inorganic magnesium aluminometasilicate, to stabilize the amorphous form of an acidic drug a neutral drug and two basic drugs. Both cryomilling and ball milling of the drug with Neusilin were...

MacLean, Jenifer Anne

2010-12-16T23:59:59.000Z

490

Torque magnetometry of an amorphous-alumina/strontium-titanate interface  

E-Print Network [OSTI]

We report torque magnetometry measurements of an oxide heterostructure consisting of an amorphous Al[subscript 2]O[subscript 3] thin film grown on a crystalline SrTiO[subscript 3] substrate (a-AO/STO) by atomic layer ...

Lee, S. W.

491

Atmospheric Oxygen Binding and Hole Doping in Deformed Graphene on a SiO2 Substrate  

E-Print Network [OSTI]

Using micro-Raman spectroscopy and scanning tunneling microscopy, we study the relationship between structural distortion and electrical hole doping of graphene on a silicon dioxide substrate. The observed upshift of the Raman G band represents charge doping and not compressive strain. Two independent factors control the doping: (1) the degree of graphene coupling to the substrate, and (2) exposure to oxygen and moisture. Thermal annealing induces a pronounced structural distortion due to close coupling to SiO2 and activates the ability of diatomic oxygen to accept charge from graphene. Gas flow experiments show that dry oxygen reversibly dopes graphene; doping becomes stronger and more irreversible in the presence of moisture and over long periods of time. We propose that oxygen molecular anions are stabilized by water solvation and electrostatic binding to the silicon dioxide surface.

Sunmin Ryu; Li Liu; Stephane Berciaud; Young-Jun Yu; Haitao Liu; Philip Kim; George W. Flynn; Louis E. Brus

2010-11-13T23:59:59.000Z

492

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

493

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