Study of the structural properties of a-SiCN: H films using hexamethyldisilazane for high-quality silicon surface passivation

We have analyzed the structural and electrical properties of a-SiCN:H films prepared by HWCVD using HMDS and related these to the deposition parameters and its passivating qualities for the purpose of optimizing these films for passivation layers of silicon solar cells. We found that deposition pressure, HMDS flow rate and H₂ flow rate had significant effects on the structural properties, chemical composition ratio and bond densities, and influenced passivation effect of a-SiCN:H films. This study indicates that hydrogen concentration derived from Si-H bond in a-SiCN:H films plays an important role in passivating qualities, while the nitrogen content and Si-N bond density are significant parameters that determine the diffusivity of hydrogen in the films. The dependence of anneal characteristics of a-SiCN:H films on nitrogen content was observed. The optimization of the composition ratio and H₂ concentration of a-SiCN:H films will lead to the high quality silicon surface passivation