Intrinsic Amorphous Silicon (a-Si:H) Thin Film Prepared by Using Remote Plasma Chemical Vapor Deposition Method and Used as a Passivation Layer for a Heterojunction Solar Cell

摘要

The hydrogenated amorphous silicon (a-Si:H) films used as intrinsic passivation layers were prepared using the radio-frequency remote-plasma chemical vapor deposition method under various deposition conditions for application to heterojunction solar cells. Their characteristics, such as their structural properties and carrier lifetimes, were investigated. When the substrate temperature was set to 250 degrees C, the optimal deposition gas ratio (r(H) = SiH4/H-2) and the RF power were 1/15 and 80 W, respectively. Furthermore, to improve the passivation effect, we performed an annealing treatment. The highest improvement was displayed at an annealing temperature of 250 C. In the FT-IR, analysis, the Si-H-2 stretching mode, which means defects in the films, was shifted to Si-H stretching mode, which means a good quality film, after annealing treatment. Moreover, the highest carrier lifetime was 1.5 ms, which is higher value than the bulk lifetime of 900 mu s. From these results, we conclude that a combination of optimal deposition conditions and annealing treatment is essential to improve the surface and bulk passivation.