Selective rounding for pyramid peaks and valleys improves the performance of SHJ solar cells

Abstract

The first step in the fabrication of SHJ (silicon heterojunction) solar cells is forming random pyramids on the Si wafer surfaces. The pyramid profile would affect the following amorphous silicon deposition. Two CP (chemical polishing) solutions consist of HNO3 + HF and O3 + HF, respectively, are used to modify the pyramid profile. It is found that these two solutions have selective rounding effects on the pyramid profiles. The first one rounds the pyramid valleys and the second one rounds the pyramid peaks. The combination of the two CP methods improves the passivation quality of amorphous silicon and promotes the conversion efficiency of SHJ cells.