Hydrogen Release and Defect Formation During Heat Treatments of SiNx:H/a-Si: H Double Passivation Layer on C-SI Substrate

The quality and temperature stability of surface passivation of silicon by a double layer consisting of a hydrogenated amorphous silicon thin film capped by a silicon nitride anti-reflection coating are studied. It is established that the passivation effect of the double layer can be significantly enhanced after short annealing for temperatures up to about 500degC, whereas annealing at higher temperatures results in degradation of the passivation properties. It is found that the increased effective recombination lifetime after annealing at temperatures below 500degC results from hydrogen redistribution in the interface region. Furthermore, presence of interfacial structural defects formed due to hydrogen release at temperatures around 600degC, is believed to be the cause of the lifetime decrease after heat treatments at higher temperatures