Application of Si-related Ultrathin (∼1 nm) Films to Crystalline Silicon Solar Cells

Abstract

Ultrathin (∼1 nm) films have been widely used for high-efficiency crystalline silicon (c-Si) solar cells such as tunnel oxide passivated contact (TOPCon) solar cells. In this article, we present our recent results for the applications of ultrathin silicon oxide (SiO_x) and silicon nitride (SiN_x) films to c-Si solar cells. The following topics are reviewed. 1) Ultrathin SiN_x can be utilized for passivating contacts instead of SiO_x in the TOPCon structure. 2) The addition of SiO_x between c-Si and thick catalytic-chemical-vapor-deposited (Cat-CVD) SiN_x significantly improves the quality of surface passivation. 3) Ultrathin Al-doped SiO_x films formed just by dipping in Al(NO₃)₃ solution on c-Si provide strong upward band bending due to negative fixed charges, which can be used for hole-selective contacts.