Comprehensive study of the doping and injection-level dependence of stoichiometric silicon nitride passivation for silicon solar cells

Abstract

The injection-level-dependence of the surface recombination velocity for the interface between crystalline silicon and stoichiometric PECVD silicon nitride has been studied. A wide variety of substrate resistivities, both n-type and p-type dopants, have been investigated for minority carrier injection-levels between 10/sup 12/-10/sup 17/ cm/sup -3/. Effective lifetimes of 10 ms have been obtained for high resistivity silicon, the highest ever measured for SiN passivated wafers, resulting in S/sub eff/ values of 1cm/s being unambiguously determined. The S/sub eff/(/spl Delta/n) dependence is very weak for n-type silicon under low injection, while for p-type silicon there is a clear minimum for injection-levels close to the doping density. Performance limits for solar cells passivated with stoichiometric SiN films are discussed and the results for actual devices with open-circuit voltages up to 675 mV presented.