Surface passivation of n-type c-Si wafers by a-Si/SiO2/SiNx stack with <1 cm/s effective surface recombination velocity

The passivation quality of an a-Si/SiO2/SiNx (aSON) stack deposited by conventional PECVD at <250 °C with and without additional corona charging of SiNx is presented. <2 fA/cm2 surface dark saturation current density and <1 cm/s effective surface recombination velocity were demonstrated on both planar and textured n-type Czochralski (CZ) substrates. It was shown that very good passivation can be achieved using <5 nm a-Si layers to provide low parasitic absorption. We also report effective minority carrier lifetimes >60 ms on 5000 Ω-cm and 20.9 ms on 1.7 Ω-cm mirror polished float zone (FZ) material passivated with aSON stacks.