Process induced improvements in polycrystalline silicon-film solar cells

Abstract

Thin polycrystalline silicon-film solar cell efficiencies and minority carrier diffusion lengths have been improved by the use of specialized processing techniques. These techniques include phosphorous gettering, aluminum gettering coupled with a deep diffusion, hydrogen passivation, SiO2 surface passivation, and low-temperature annealing. A processing sequence combining several of these techniques has resulted in minority carrier diffusion length increases of up to 100% and in the achievement of a 15.7% 1 cm/sup 2/ laboratory-scale solar cell. Transfer of the processes to commercial-scale devices has led to similar increases in minority carrier diffusion lengths and to efficiency improvements of up to 30%.<>