Silicon lifetime enhancement by SiN_x:H anti-reflective coating deposed by PECVD using SiH_4 and N_2 reactive gas

摘要

Hydrogenated films of silicon nitride SiN_x:H are largely used as antireflective coating as well as passivation layer for industrial crys talline and multicrystalline silicon solar cells. In this work, we present a low cost plasma enhanced chemical vapor deposition (PECVD) of this thin layer by using SiH_4 and N_2 as a reactive gases. A study was carried out on the variation effect of the ratio silane (SiH_4) to nitrogen (N_2) and time deposition on chemical composition, morphologies, reflectivity and carrier lifetime. The thickness was varied, in order to obtain a homogeneous antireflective layer. The Fourier transmission infrared spectroscopy (FTIR) shows the existence of Si-N and Si-H bonds. The morphologies of the sample were studied by Atomic Force Microscopy (AFM). The resulting surface of the SiN_xH shows low-reflectivity less than 5% in wavelength range 400-1200 nm. As a result, an improvement in minority carrier lifetime has been achieved to about 15 μs.