Si surface passivation by SiO_x:H films deposited by a low-frequency ICP for solar cell applications

摘要

Hydrogenated silicon suboxide (SiO_x:H) thin films are fabricated by a low-frequency inductively coupled plasma of hydrogen-diluted SiH 4+CO _2 at a low temperature (100°C). Introduction of a small amount of oxygen into the film results in a predominantly amorphous structure, wider optical bandgap, increased H content, lower conductivity and higher activation energy. The minority carrier lifetime in the SiO_x:H-passivated p-type Si substrate is up to 428μs with a reduced incubation layer at the interface. The associated surface recombination velocity is as low as 70cms ~1. The passivation behaviour dominantly originates from the H-related chemical passivation. The passivation effect is also demonstrated by the excellent photovoltaic performance of the heterojunction solar cell with the SiO_x:H-based passivation and emitter layers.