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Silicon Materials Task of the Low Cost Solar Array Project (Phase II). Effect of impurities and processing on silicon solar cells. Phase II. Summary and eleventh quarterly report

Technical Report ·
DOI:https://doi.org/10.2172/6567743· OSTI ID:6567743
The effects of various processes, metal contaminants and contaminant-process interactions on the performance of terrestrial silicon solar cells were investigated. A variety of aspects including thermal treatments, crystal growth rate, base doping concentration (low resistivity), base doping type (n vs. p), grain boundary structure, and carbon/oxygen-metal interactions (float zone vs Czochralski growth) were studied. The effects of various metallic impurities were studied, introduced singly or in combination into Czochralski, float zone and polycrystalline silicon ingots and into silicon ribbons grown by the dendritic web process. The totality of the solar cell data (comprising over 4000 cells) indicate that impurity-induced performance loss is primarily due to reduction in base diffusion length. Based on this assumption an analytical model has been developed which predicts cell performance as a function of metal impurity content. The model has now been verified for p-base material by correlating the projected and measured performance of solar cells made on 19 ingots bearing multiple impurities.
Research Organization:
Westinghouse Electric Corp., Pittsburgh, PA (USA). Research and Development Center
DOE Contract Number:
NAS-7-100-954331
OSTI ID:
6567743
Report Number(s):
DOE/JPL/954331-3
Country of Publication:
United States
Language:
English