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
Similar Records
Vacuum deposited polycrystalline silicon films for solar cell applications. Quarterly technical progress report No. 1, September 29-December 31, 1978
Vacuum deposited polycrystalline silicon films for solar cell applications. Quarterly report, 1 April-30 June 1980
Related Subjects
36 MATERIALS SCIENCE
SILICON
SPUTTERING
VACUUM COATING
SILICON SOLAR CELLS
FABRICATION
PERFORMANCE
CHARGE CARRIERS
CRYSTAL DOPING
DIFFUSION LENGTH
ELECTRICAL PROPERTIES
EXPERIMENTAL DATA
FILL FACTORS
FILMS
GRAIN SIZE
GRAPHS
IMPURITIES
ION MICROPROBE ANALYSIS
POLYCRYSTALS
SCANNING ELECTRON MICROSCOPY
SPECTRAL RESPONSE
SUBSTRATES
TITANIUM BORIDES
X-RAY DIFFRACTION
BORIDES
BORON COMPOUNDS
CHEMICAL ANALYSIS
COHERENT SCATTERING
CRYSTAL STRUCTURE
CRYSTALS
DATA
DEPOSITION
DIFFRACTION
DIMENSIONS
DIRECT ENERGY CONVERTERS
ELECTRON MICROSCOPY
ELEMENTS
EQUIPMENT
INFORMATION
LENGTH
MICROANALYSIS
MICROSCOPY
MICROSTRUCTURE
NONDESTRUCTIVE ANALYSIS
NUMERICAL DATA
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
SCATTERING
SEMIMETALS
SIZE
SOLAR CELLS
SOLAR EQUIPMENT
SURFACE COATING
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
140501* - Solar Energy Conversion- Photovoltaic Conversion
360601 - Other Materials- Preparation & Manufacture