椭偏法表征四面体非晶碳薄膜的化学键结构  

Determination of Chemical Bond of Tetrahedral Amorphous Carbon Films by Ellipsometry Approach

作　　者：李晓伟 周毅 孙丽丽[1] 汪爱英[1] 

机构地区：[1]中国科学院宁波材料技术与工程研究所宁波市海洋防护材料与工程技术重点实验室,浙江宁波315201

出　　处：《光学学报》2012年第10期298-304,共7页Acta Optica Sinica

基　　金：浙江省自然科学基金(Y4100312);宁波市重大科技专项(2011B1016);宁波市科技项目(2010D10015;2010A0203)资助课题

摘　　要：采用自主研制的双弯曲磁过滤阴极真空电弧(FCVA)技术,在不同衬底负偏压下制备了四面体非晶碳(ta-C)薄膜。通过分光光度计和椭偏(SE)联用技术精确测量了薄膜厚度,重点采用椭偏法对不同偏压下制备的ta-C薄膜sp3 C键和sp2 C键结构进行了拟合表征,并与X射线光电子能谱(XPS)和拉曼光谱的实验结果相对比,分析了非晶碳结构的椭偏拟合新方法可靠性。结果表明,在-100V偏压时薄膜厚度最小,为33.9nm;随着偏压的增加,薄膜中的sp2 C含量增加,sp3 C含量减小,光学带隙下降。对比结果发现,椭偏法作为一种无损、简易、快速的表征方法,可用于ta-C薄膜中sp2 C键和sp3 C键含量的准确测定,且在采用玻璃碳代表纯sp2 C的光学常数及拟合波长选取250～1700nm时的椭偏拟合条件下,拟合数值最佳。Tetrahedral amorphous carbon （ta-C） films under different substrate negative bias are prepared by a home developed filtered cathodic vacuum arc （FCVA） technology with double bend shape. The film thickness is measured by a combined spectrophotometry and spectroscopic ellipsometry （SE） approach; the chemical bonds including sp2C and sp3C are gained by the fitted ellipsometry method. Furthermore, the accuracy of ellipsometry results is evaluated by comparing with those of X-ray photoelectron spectroscopy （XPS） and Raman spectra. The results indicate that the minimum thickness of ta-C film of 33.9 nm is obtained when the bias voltage is --100 V; with the increase of bias voltage, the optical gaps and the content of sp3C atomic bond decrease, while the sfC content increases correspondingly. By comparison with the results of XPS and Raman spectra, it is found that when the optical constants of sp2C model are represented by the glassy carbon and the fitting wavelength ranges are chosen from 250 to 1700 nm, the best fitting result of atomic bonds of ta-C films can be deduced by the ellipsometry method. Therefore, it could be said that the elliposometry method is a quite promising method to characterize the atomic bonds of ta-C films including sp2C and sp3C, as a new nondestructive, fast, quantitative and easy way.

关 键 词：薄膜 化学键 椭偏法 磁过滤阴极真空弧 四面体非晶碳 

分 类 号：O484.41[理学—固体物理]