Tunnel nitride passivated contacts for silicon solar cells formed by catalytic CVD

Abstract

An ultra-thin silicon nitride (SiN x ) layer formed by catalytic chemical vapor deposition (Cat-CVD) is used to replace the Si dioxide (SiO2) layer of a tunnel oxide passivated contact solar cell. The passivation quality of crystalline Si (c-Si) with a stack of the ultra-thin SiN x and n-type hydrogenated amorphous Si (a-Si:H) or microcrystalline Si (μc-Si:H), also formed by Cat-CVD, is significantly improved by annealing at 850 °C, probably due to the formation of a back surface field layer. Cat-CVD SiN x with thicknesses of up to 2.5 nm can have sufficient tunneling conduction. The ultra-thin SiN x having functions of surface passivation and carrier tunneling, and the unification of the formation method for the tunnel SiN x and conductive layers will lead to the realization of tunnel nitride passivated contact solar cells.