Process research on polycrystalline-silicon material (PROPSM). Quarterly report No. 8, October 1-December 31, 1982
Performance-limiting mechanisms in polycrystalline silicon were investigated by fabricating a matrix of 4 cm/sup 2/ solar cells of various thicknesses from 10 cm x 10 cm polycrystalline silicon wafers of several bulk resistivities. The analysis of the results for the entire matrix indicates that bulk recombination is the dominant factor limiting the short-circuit current in large-grain (greater than 1 to 2 mm diameter) polycrystalline silicon, the same mechanism that limits the short-circuit current in single-crystal silicon. The average open-circuit voltage of the polycrystalline cells is 30 to 70 mV lower than that of the single-crystal (control) cells; the fill-factor is comparable. Both open-circuit voltage and fill-factor have substantial scatter which is not related to thickness or resistivity. This implies that these parameters are sensitive to an additional mechanism which is probably spatial in nature since the cell position on the wafer was not controlled. An experiment to investigate the limiting mechanisms of open-circuit voltage and fill-factor for large-grain polycrystalline silicon was designed. Two process sequences to fabricate small cells were investigated. For the first process sequence, cell-to-cell isolation was obtained by masking the wafer during diffusion (with SiO/sub 2/) so that a P-type silicon surface remains between neighboring cells. In the alternate process, cell isolation was realized by etching away silicon to form a mesa structure. This process sequence was ultimately chosen to fabricate the mini-cells because of its comparative insensitivity to process variables.
- Research Organization:
- Solarex Corp., Rockville, MD (USA)
- DOE Contract Number:
- NAS-7-100-955902
- OSTI ID:
- 6030718
- Report Number(s):
- DOE/JPL/955902-82/8; ON: DE83011866
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
ANTIREFLECTION COATINGS
COATINGS
CRYSTALS
CURRENTS
DATA
DIRECT ENERGY CONVERTERS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRIC POTENTIAL
ELECTRICAL PROPERTIES
EQUIPMENT
EXPERIMENTAL DATA
FABRICATION
FILL FACTORS
INFORMATION
MONOCRYSTALS
NUMERICAL DATA
PERFORMANCE
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
POLYCRYSTALS
RECOMBINATION
SILICON SOLAR CELLS
SOLAR CELLS
SOLAR EQUIPMENT