Effect of H2 Flow Rate on Microstructure and Optical Property of Nanocrystalline SiC Films
氢流量对纳米SiC薄膜微结构和光学特性的影响

Nanocrystalline (nc) SiC thin films were deposited by helicon wave plasma enhanced chemical vapor deposition technique. The effects of H2 flow rate on the microstructure and optical property of the deposited films were investigated. The deposition rate increases firstly and then decreases with H2 flow rates increasing, while the crystallization degree of the films increases monotonically. At low H2 flow rate, the optical band gap increases initially and then decreases, which is determined by the competition of surface reaction between hydrogen etching and dangling bond terminating. At high H2 flow rate, the relative density of hydrogen bonding existing in the surface of the nano-SiC increases continuously although the total H content in the films reduces. The increase of the nano-SiC grain quantity and the decrease of the grain size make the optical band gap increase further due to the quantum confinement effect.