Abstract: 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.

Key words: nanocrystalline SiC, H₂ flow rate, microstructure, optical property