Effect of high temperature steam annealing for SiO2 passivation

We introduced high-temperature steam annealing (HSA) as a low-cost and effective post-annealing method for c-Si solar cell processing. The annealing effects were analyzed by measuring effective lifetime and C–V characteristics and were compared with the effects of forming gas annealing (FGA) and hydrogen-radical annealing (HRA). By using this method, effective lifetime of a SiO₂-coated wafer was increased in a very short annealing time compared to the conventional FGA. It was determined that the improvement of lifetime by HSA can be attributed to the decrease of interface state density.