氢流量对纳米SiC薄膜微结构和光学特性的影响

采用螺旋波等离子体增强化学气相沉积技术进行了氢化纳米晶态SiC薄膜的沉积,研究了氢流量对其微结构和光学特性的影响.结果显示,随着氢气流量的增大,薄膜的沉积速率先增大后减小,所生长薄膜晶化度显著提高.在较低氢流量条件下,薄膜光学带隙的大小由氢的刻蚀与悬键终止作用共同控制,并呈先减小后增大的趋势.在高氢流量条件下,强的氢刻蚀使薄膜具有较高的晶化度,虽然薄膜中整体氢含量有所下降,但存在于纳米碳化硅晶粒表面键合氢的相对密度持续增大,纳米碳化硅晶粒数量的增加和晶粒尺寸的减小所导致的量子限制效应使薄膜的光学带隙继续展宽.

Effect of H2 Flow Rate on Microstructure and Optical Property of Nanocrystalline SiC Films

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.