过滤电弧沉积非晶金刚石薄膜的光谱椭偏研究

为了深入理解过滤阴极电弧沉积非晶金刚石薄膜的光学性质,利用光谱椭偏仪研究了薄膜光学常数随测试偏振光波长变化的谱学关系,进而分析了薄膜折射率、消光系数和光学带隙与沉积能量之间的变化规律.实验表明,非晶金刚石薄膜的折射率高于金刚石晶体的折射率,薄膜的吸收光谱在高吸收区可以用抛物线型函数描述,并由此计算Tauc带隙.随着波长向红外延伸,非晶金刚石薄膜的消光系数渐次降低并趋近于零,光学常数因沉积能量变化而实现的调整幅度也逐渐缩小.随着衬底偏压的增加,折射率和光学带隙都是先升高后减小,并在负偏压为80 V时有最大值;而消光系数却是先减小再升高,在负偏压为80 V时有最小值.

Spectroscopic Ellipsometry Investigations of Amorphous Diamond Films Deposited with Filtered Arc

In order to investigate thoroughly the optical properties of amorphous diamond (alpha-D) films deposited by the filtered vacuum arc technology, the optical constants of the films were measured by spectroscopic ellipsometry. Moreover, the dispersion relations of the optical constants, and the correlations among refractive index, extinction coefficient, optical gap and the substrate bias were also analyzed. It has been shown that the refractive index of alpha-D films is higher than that of diamond crystal, and the absorption edge corresponding to the interband transformation can be described with the parabolic line shape. With increasing the wavelength, the extinction coefficient gradually declines and approaches nearly to zero in the infrared band. In addition, the adjustable amplitudes of the optical constants owing to the changing bias also reduce strikingly with the extension of the wavelength. With raising the bias, the refractive index and the optical gap firstly augment, then minish, and there is a maximal value when the substrate bias is -80 V. However, the extinction coefficient firstly minishes, then augments, and there is a minimal value when the bias is -80 V.