고효율 결정질 실리콘 태양전지 적용을 위한 p타입 에미터 표면의 전계 효과를 이용한 실리콘 산화막 패시베이션

Abstract

The surface passivation is one of the crucial steps to achieve high conversion efficiencies in c-Si solar cells. A thermallystable thin film with a negative charge (for p-type surface) passivation layer is required to develop a good front passivation suitable forn-type c-Si solar cells. Silicon suboxide (SiOX) layer using PECVD provides a good passivation layer which has low temperatureprocess and charge control in thin-film layer. In this paper, a PECVD stack layer consisting of SiOX and SiNX was employed for frontside passivation. The optimal refractive index of SiOX and SiNX were found by varying the silane (SiH4), ammonia (NH3) and nitrousoxide (N2O) gas ratio for decrease optical loss. -1.71 × 1011cm-2of negative charge (Qf) and 5×1010cm-2eV-1of Dit (interface trapdensity) were obtained at 10 nm thick SiOX thin-film. With this optimized SiOx/SiNx stack layer on p+surface wafer using PECVD,the effective lifetime of 280 ㎲ and implied VOC of 690 mV were achieved. It is expected that the efficiency of the n-type silicon solarcell can be improved by applying the optimized SiOx condition to the front passivation layer.