Vacuum-deposited polycrystalline silicon films for solar-cell applications. Final technical report, September 14, 1979-December 1, 1980
A potentially all-vacuum fabrication process for forming thin film polycrystalline silicon solar cells has been explored in which the solar cell was constructed in layers, as follows: alumina (or sapphire) substrate/TiB/sub 2/ bottom electrode/p-type polycrystalline silicon film/n-type polycrystalline silicon film/Ti-Ag top electrode. Techniques were developed for forming stable, low resistivity thin films of TiB/sub 2/. The p-layer was vacuum deposited by electron beam heating of Si and B sources. The n-layer was formed both by thermal diffusion and by silicon deposition in a phosphine atmosphere. Both methods yielded photodiodes; the diffused junctions were studied more extensively and consequently produced the higher efficiency devices. Emphasis was placed on producing thin (10 to 15 ..mu..m) silicon films with high purity and large grain size (20 to 40 ..mu..m). The presence of the underlying TiB/sub 2/ layer was found to be essential for the growth of large Si grains. The interactions between Si and TiB/sub 2/ were studied extensivey by secondary ion mass spectrometry (SIMS) and x-ray diffraction techniques. SIMS was also used to determine doping and impurity profiles. The best photovoltaic response without an antireflection coating was obtained from small (less than or equal to 1 mm/sup 2/) devices with base p-type region grain sizes larger than 5 ..mu..m; typical AM-1 photovoltaic parameters were: V/sub oc/ approx. = 300 mV, J/sub sc/ approx. = 14 mA/cm/sup 2/ ff approx. = 0.60, eta approx. = 2.5%. Recommendations are made for further studies which should lead to improved performance of the thin film cells.
- Research Organization:
- Johns Hopkins Univ., Laurel, MD (USA). Applied Physics Lab.
- DOE Contract Number:
- AC02-77CH00178
- OSTI ID:
- 6890597
- Report Number(s):
- SERI/TR-8278-1-T4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
BORIDES
BORON COMPOUNDS
CHARGE CARRIERS
CHEMICAL ANALYSIS
COHERENT SCATTERING
CRYSTAL DOPING
CRYSTAL STRUCTURE
CRYSTALS
DATA
DEPOSITION
DIFFRACTION
DIFFUSION LENGTH
DIMENSIONS
DIRECT ENERGY CONVERTERS
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
ELEMENTS
EQUIPMENT
EXPERIMENTAL DATA
FABRICATION
FILL FACTORS
FILMS
GRAIN SIZE
GRAPHS
IMPURITIES
INFORMATION
ION MICROPROBE ANALYSIS
LENGTH
MICROANALYSIS
MICROSCOPY
MICROSTRUCTURE
NONDESTRUCTIVE ANALYSIS
NUMERICAL DATA
PERFORMANCE
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
POLYCRYSTALS
SCANNING ELECTRON MICROSCOPY
SCATTERING
SEMIMETALS
SILICON
SILICON SOLAR CELLS
SIZE
SOLAR CELLS
SOLAR EQUIPMENT
SPECTRAL RESPONSE
SPUTTERING
SUBSTRATES
SURFACE COATING
TITANIUM BORIDES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
VACUUM COATING
X-RAY DIFFRACTION