Recombination at the interface between silicon and stoichiometric plasma silicon nitride

Abstract

The injection level dependence of the effective surface recombination velocity (Seff) for the interface between crystalline silicon and stoichiometric silicon nitride, prepared by high-frequency direct plasma enhanced chemical vapour deposition (PECVD), has been comprehensively studied. A wide variety of substrate resistivities for both n-type and p-type dopants have been investigated for minority carrier injection levels (Δn) between 1012 and 1017 cm-3. Effective lifetimes of 10 ms have been measured for high resistivity n-type and p-type silicon, the highest ever measured for silicon nitride passivated wafers, resulting in Seff values of 1 cm s-1 being unambiguously determined. The Seff(Δn) dependence is shown to be constant for n-type silicon under low injection conditions, while for p-type silicon, there is a clear minimum to Seff for injection levels close to the doping density. Further, the Seff(Δn) dependence for these stoichiometric silicon nitride films appears to be weaker than that for other high-quality, silicon-rich silicon nitride films prepared by remote PECVD.