Microstructure evolution and passivation quality of hydrogenated amorphous silicon oxide (a-SiOx:H) on 〈100〉- and 〈111〉-orientated c-Si wafers*

Abstract

Hydrogenated amorphous silicon oxide (a-SiO x :H) is an attractive passivation material to suppress epitaxial growth and reduce the parasitic absorption loss in silicon heterojunction (SHJ) solar cells. In this paper, a-SiO x :H layers on different orientated c-Si substrates are fabricated. An optimal effective lifetime (τ eff) of 4743 μs and corresponding implied open-circuit voltage (i V oc) of 724 mV are obtained on 〈100〉-orientated c-Si wafers. While τ eff of 2429 μs and i V oc of 699 mV are achieved on 〈111〉-orientated substrate. The FTIR and XPS results indicate that the a-SiO x :H network consists of SiO x (Si-rich), Si– OH, Si– O– SiH x , SiO2≡Si– Si, and O3 ≡S– Si. A passivation evolution mechanism is proposed to explain the different passivation results on different c-Si wafers. By modulating the a-SiO x :H layer, the planar silicon heterojunction solar cell can achieve an efficiency of 18.15%.