The influence of surface preparation on rear surface passivation of mc-Si by thermally treated direct PECVD silicon nitride

Bulk and surface passivating properties of low frequency direct PECVD SiN/sub x/:H were investigated on 0.5-1 /spl Omega/cm p-type mc-Si material. It is observed that bulk passivation is preserved for different SiN/sub x/:H layers, deposited in a wide range of gas flow ratio and power. This allows optimisation of the layer composition towards rear surface passivation of mc-Si, while maintaining the bulk passivation. Lifetime measurements showed that a thermal treatment of SiN/sub x/:H leads to a lower minority carrier trapping density in the mc-Si bulk. Also a strong effect of the surface condition on the surface passivation was found. Different surface conditions have a strong impact on blister formation, which are possibly related to the diffusion mechanism of hydrogen from SiN/sub x/:H into the mc-Si bulk.