摘要:

We present initial results of a study whose goal is to develop a process leading to SiC p-layers compatible with a superstrate p-i-n cell structure, deposited in an RF PECVD system. Experimental variables were dopant gas,CH4andH2gas flows normalized to the sum ofSiH4andCH4flows, and the power. Compared toB2H6,doping withB(CH3)3lowered the conductivity by a factor of 40 and reduced the fraction of crystallinity from 87&percent; to 53&percent;. The c-Si fraction decreased strongly with increasingCH4flow. No evidence of Si-C bonding was identified in the Raman spectra of these samples. Finally, it has been demonstrated that high conductivity p-layers (>1 S/cm) having high c-Si volume fraction (∼85&percent;) can be deposited on glass at low power density (84 mW/cm2) which is compatible with deposition on TCO substrates for device fabrication. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57972

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

By measuring both the mechanical stress and the optoelectronic properties of a-Si:H films before and after light-soaking, we have examined the film structural stability in relation to its electronic stability. A photoinduced increase of the compression, in the order of10−4of the initial value, was found in both the glow discharge and hot-wire films. A factor of 4-6 photodegradation of the photoconductivity was obtained in the HW films deposited atTS<360&hthinsp;°C,but there was no photodegradation for the films deposited at360<TS<440&hthinsp;°C.Hence, there is no obvious relation between the changes in film structure (observed by IR and stress) and the Staebler—Wronski Effect (SWE). ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57973

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

For the “Hot Wire” chemical vapor deposition (HWCVD) method to be applicable for photovoltaic applications certain critical technical issues need to be addressed and resolved such as, lifetime of the filaments used, reproducibility, large area demonstration of the material and stable devices. We have developed a new approach which addresses some of these problems, specifically longevity of the filaments and reproducibility of the materials produced. This new technique does not seem to introduce contaminants into the materials from the source and can produce high quality amorphous Silicon (intrinsic and doped) and intrinsic microcrystalline silicon films. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57903

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

A series ofa-Si1−xGex:Halloys with0⩽x⩽1has been prepared by the hot-wire chemical-vapor deposition method and characterized by the small-angle x-ray scattering technique. All samples are inhomogeneous on a nanometer scale with a significant increase in the amount of heterogeneity abovex=0.1and this correlates with degraded opto-electronic properties. Oriented features detected in the nanostructure are associated with a directed flux of deposition species from the heated filament. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57974

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

A scanning tunneling microscope in ultrahigh vacuum is used to measure the profile of electronic properties of cleaved amorphous silicon solar cells. Their exposed layers in a single and a tandem cell can be identified by their characteristic current—voltage dependencies (scanning tunneling spectroscopy). An “Apparent Potential” is measured throughout the cells. The results for the tandem cell from SOLAREX, Inc. are shown. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57975

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Hydrogen out-diffusion from the n/i interface region plays a major role in controlling the fill factor (FF) and resultant efficiency of n-i-p a-Si:H devices, with the i-layer deposited at high substrate temperatures by the hot wire technique. Modeling calculations have shown that a thin, highly defective layer at this interface, perhaps caused by significant H out-diffusion and incomplete lattice reconstruction, results in sharply lower device FFs due to the large voltage dropped across this defective layer. We have therefore employed buffer layers designed to retard this out-diffusion. We find that an increased H content, either in the n-layer or a thin intrinsic low temperature buffer layer, does not significantly retard this out-diffusion, as observed by SIMS H profiles on devices. However, if this low temperature buffer layer is thick enough, the out-diffusion is minimized, yielding nearly flat H profiles and a much improved device performance. We discuss this behavior in the context of the H chemical potentials and H diffusion coefficients in the high temperature, buffer, n-, and stainless steel substrate layers. Finally, we report a 9.8&percent; initial active area device, fabricated at 16.5 Å/s, using the insights obtained in this study. Light soaking data are also reported. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57904

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

This paper describes major features of a new optical software package,PV Optics, and presents a brief summary of the results of applying this program to analyze amorphous silicon solar cells. Some examples are given, mainly to demonstrate the nature of calculations that can be performed with this program for a-Si cell design. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57976

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

In this paper, we report the recent progress in our newly established amorphous silicon (a-Si) based photovoltaic research program at The University of Toledo (UT). Under the Thin Film Partnership subcontract which started in March 1998, we have achieved the fabrication of 1) wide bandgap a-Si solar cells with 1.02 V open circuit voltage using high hydrogen dilution for the i-layer deposition, 2) mid bandgap a-Si solar cells having a high fill factor of 0.732, 3) narrow bandgap a-SiGe solar cells with 8.3&percent; initial efficiency and a red response of nearly 50&percent; at 800 nm, and 4) triple-junction, spectrum-splitting a-Si/a-SiGe/a-SiGe solar cells with 9.7&percent; initial efficiency. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57905

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

A 70 MHz Very High Frequency (VHF) Plasma Enhanced Chemical Vapor Deposition (PECVD) technique has been used to prepare i-layers for small area, single-junction a-Si:H and a-SiGe:H nip cells and triple-junction devices at deposition rates as high as 10 Å/s. For both the a-Si:H and a-SiGe:H single-junction cells under optimized deposition conditions, the efficiencies and the light stability remain relatively constant as the i-layer deposition rate is varied from 1 to 10 Å/s. Also the stable efficiencies for both types of cells are similar to those for similar cells made in the same deposition system at low deposition rates (1 Å/s) using the standard 13.56 MHz PECVD technique. Triple-junction a-Si:H/a-SiGe:H/a-SiGe:H cells have been fabricated using the VHF technique to prepare all of the i-layers at deposition rates near 10 Å/s. These devices have pre-light soaked active area efficiencies between 9.5 and 10&percent; and total area efficiencies between 9.0 and 9.5&percent;. Considering these results, the VHF method is a promising technique to increase the growth rate of i-layers for a-Si:H based devices, and when applied to the production of large area a-Si:H based multi-junction solar modules, it will allow for higher manufacturing throughput and reduced module cost. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57977

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

The AMPS-1D PC computer program is now used by over 70 groups world-wide for detector and solar cell analysis. It has proved to be a very powerful tool in understanding device operation and physics for single crystal, poly-crystalline and amorphous structures. For example, AMPS-1D has been successful in explaining the “red kink” [1] and the “transient effect” in CdS/CIGS poly-crystalline solar cells. It has been used to show that thin film poly-Si structures, with reasonable light trapping, are capable of competitive solar cell conversion efficiencies. In the case of a-Si:H structures, it has been used, for example, to settle the discrepancies in bandgap measurement, to predict the effectiveQE>1phenomenon later seen in these materials [2], to determine the relative roles of interface and bulk properties, and to point the direction toward 16&percent; triple junction structures. In general AMPS-1D is used for cell and detector design, material parameter sensitivity studies, and parameter extraction. Recently we have shown that it can be used to determine optimum structure and light and voltage biasing conditions in the material parameter extraction function. Information on AMPS can be found at www.psu.edu/dept/AMPS/amps_web/AMPS.html and at other web sites set up by user groups. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.57978

出版商:AIP    

年代:1999

数据来源: AIP