掺氮类金刚石薄膜的微观结构和红外光学性能研究

采用俄歇电子能谱、原子力显微镜、拉曼散射分析、傅里叶红外光谱和红外椭圆偏振光谱等设备,对射频等离子增强化学气相沉积法制备的掺氮类金刚石薄膜的微观结构和红外光学性能进行了研究.结果表明,薄膜中氮含量随工艺中氮气/甲烷流量比的增加而增加并趋于饱和.光谱中CH键吸收峰(2859~3100cm^-1)逐渐消失,而且CNH键(1600cm^-1)、C≡N键(2200cm^-1)和NH键(3250cm^-1)对应的红外吸收峰强度随氮含量的增加而增加.拉曼散射中G峰向小波数方向位移和峰值展宽的现象说明薄膜中形成了非晶的氮化碳结构,与原子力显微镜显示的薄膜中富氮的非晶纳米颗粒相对应.偏振光谱分析认为,富氮纳米颗粒的存在导致了薄膜在红外波段折射率由1.8降低到1.6.

Microstructure and Infrared Optical Properties of the Hydrogenate Carbon Nitride Film

The microstructure and optical properties of nitrogen doped hydrogenated carbon DLC∶N film deposited by rf plasma enhanced chemical vapor deposition(PECVD)method were studied with the help of AFM, Raman, FTIR and IRE spectrometer. Absorption intensities of the peaks CNH(1600cm-1)，CN(2200cm-1)and NH(3250cm-1)in the IR spectra increase with the ratio of flow N2/CH4. Raman spectra show that the shape of D and G band of DLC∶N film varies slightly with the increase of N content, which means that the main structures of N doped films are still DLC. However, Gaussian fit results show that G band widens and the peak shifts to the low wavenumber in Raman spectra because amorphous C3N4 structure has formed in the film. AFM topographies and LFM images of DLC∶N film confirm that the amorphous C3N4 exists as several tens nanometer particles in the film. IRE spectra analysis results show that refractive index of the film in infrared band(2～14 μm)slightly decreases from 1.8 to 1.6 with increased nitrogen content in the films.