결정질 실리콘 태양전지의 패시베이션 적용을 위한 Al2O3/SiON 적층구조의 열적 안정성에 대한 연구

Abstract

We investigated the influence of blistering on Al₂O₃/SiON stacks and Al₂O₃/SiNx:H stacks passivation layers. Al₂O₃ film provides outstanding Si surface passivation quality. Al₂O₃ film as the rear passivation layer of a p-type Si solar cell is usually stacked with a capping layer, such as SiO₂, SiNx, and SiON films. These capping layers protect the thin Al₂O₃ layer from an Al electrode during the annealing process. We compared Al₂O₃/SiON stacks and Al₂O₃/SiNx:H stacks through surface morphology and minority carrier lifetime after annealing processes at 450℃ and 850℃. As a result, the Al₂O₃/SiON stacks were observed to produce less blister phenomenon than Al₂O₃/SiNx:H stacks. This can be explained by the differences in the H species content. In the process of depositing SiNx film, the rich H species in NH₃ source are diffused to the Al₂O₃ film. On the other hand, less hydrogen diffusion occurs in SiON film as it contains less H species than SiNx film. This blister phenomenon leads to an increase insurface defect density. Consequently, the Al₂O₃/SiON stacks had a higher minority carrier lifetime than the Al₂O₃/SiNx:H stacks.