Microstructure and Optical Properties of Hydrogenated Amorphous Silicon Nitride Films Deposited by Helicon Wave Plasma Enhanced Chemical Vapor Deposition

The atomic configurations and optical properties of hydrogenated amorphous silicon nitride (α-SiNx:H) films deposited by helicon wave plasma enhanced chemical vapor deposition (HWP-CVD) were analyzed by using Fourier transform infrared (FTIR) spectroscopy and ultraviolet-visible (UV-VIS) spectroscopy. The results reveal that the films show different Si/N ratio and hydrogen bonding mode at the various ratio between the silicon and nitrogen containing gases (R), For nitride-rich samples, hydrogen has a chemical preference to bind to nitride. On the other hand, for silicon-rich samples, hydrogen atoms bind preferentially to silicon. The optical band gap, Eg and E04 of α-SiNx:H films decrease gradually with the increase of R, which is attributed to the increase of disorder degree of the α-SiNx:H film microstructure. Additionally, the correlation between (E04-Eg) and the slop of Tauc plot, B for the α-SiNx:H films is established.