Characterization of the effects of metallic impurities on silicon solar cell performanceThe effects of controlled concentrations of secondary impurities (Al, C, Ca, Cr, Cu, Fe, Mg, Mn, Mo, Ta, Ti, V, Zn, and Zr), incorporated alone or in combinations into Czochralski and float zone crystals, on the performance of silicon solar cells were investigated. Impurity concentrations ranged from 10 to the 11th to 10 to the 17th/cu cm. Solar cells were fabricated by a conventional diffusion process and characterized by computer reduction of current-voltage data. The data suggest that performance loss primarily results from reduction of the base diffusion length. On the basis of this assumption, a first order analytic model which predicts cell performance as a function of impurity concentrations is developed. Calculated performance parameters are in good agreement with observation, except for some impurities, such as Fe, Cu and Ni, which degrade cells via recombination and defects in the junction space-charge region. N-base devices are less affected by impurities, although degradation mechanisms appear to be the same as in p-devices. There seems to be very limited interaction between impurities in multiply-doped cells.
Document ID
19790056947
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Davis, J. R. (Westinghouse Research and Development Center Pittsburgh, PA, United States)
Rohatgi, A. (Westinghouse Research and Development Center Pittsburgh, PA, United States)
Rai-Choudhury, P. (Westinghouse Research and Development Center Pittsburgh, PA, United States)
Blais, P. (Westinghouse Research and Development Center Pittsburgh, PA, United States)
Hopkins, R. H. (Westinghouse Research and Development Center Pittsburgh, Pa., United States)
Mccormick, J. R. (Dow Corning Corp. Midland, Mich., United States)