低粗糙度金刚石薄膜的制备及其光学性能的表征

Growth and Optical Performance of Diamond Films with Low Surface Roughness

采用热丝化学气相沉积(HFCVD)方法,在反应气压、衬底温度一定的情况下,通过改变碳源浓度以制备低粗糙度金刚石薄膜.扫描电镜(SEM)和原子力显微镜(AFM)测试结果表明,随着碳源浓度适当增加(从2%增加到3%),金刚石薄膜表面晶粒尺寸减小到纳米量级,平均粗糙度从45 nm降低到21 nm,同时光学透过率下降.椭圆偏振光谱拟合结果显示,随着碳源浓度的增加,薄膜折射率n稍有偏离理想值.拉曼散射光谱显示随着碳源浓度的增加,薄膜中非金刚石相含量增加,一定程度上影响了薄膜的光学质量.结果表明,在表面粗糙度相差不大的情况下,薄膜的质量决定了其光学性质.

A series of polycrystalline diamond films with different surface roughness were successfully deposited on silicon substrates using the HFCVD method with varying carbon content in the range of 2%-3 %. Scanning electron microscopy （SEM）, atomic force microscopy （AFM）, Raman scattering spectroscopy, and optical transmission spectroscopy and spectroscopic ellipsometry were employed to characterize the as-grown films. With increase of carbon content, average roughness of the diamond films was reduced from 45 nm to 21 nm while their grain size was lowered to tens of nanometers. The refractive index （n） came to offset the idealized value as well. The effects of film＇ s surface roughness and content of the non-diamond phase on the optical property were studied. It was observed that the films＇ quality determines their optical performance when they have similar surface roughness.