Effect of SiH_4 Flow Rates on the Structures and Properties of Si-Rich Silicon Nitride Films Prepared by Hot Wire Chemical Vapor Deposition

摘要

Silicon-rich silicon nitride thin films were deposited on silicon P type (100) and Corning7059 glass by hot-wire chemical vapor deposition using SiH_4 and NH_3 as reaction gas source. The effects of SiH_4 flow rate on the structures and optical properties of the thin films were studied and deposition parameters optimized. The structures, band gap width and surface morphology of the thin films were characterized by Fourier transform infrared absorption spectroscopy (FTIR), ultraviolet-visible (UV-VIS) light transmittance spectra and scanning electron microscope (SEM), respectively. With increasing of the SiH_4 flow rate, the content of N and Si atoms in the thin films is found to increase, the Si-N bond density increases gradually, and the optical band gap of the films shows an increasing trend. When the silane flow rate is less than 0.9 sccm, there is no Si-H bond stretching vibration absorption peak, and silicon atoms mainly bond with nitrogen atoms. As the SiH_4 flow rate decreases, the silicon clusters embedded in silicon nitride matrix gradually become smaller. When SiH_4 flow rate is 0.4 sccm, silicon cluster nanoparticles with an average diameter of about 50 nm are obtained embedded in silicon nitride thin films matrix. Therefore, an appropriate reduction of the SiH_4 flow rate is favorable to prepare smaller silicon cluster nanoparticles. The results pay the way for the preparation of silicon quantum dots thin film materials.