纳米金刚石薄膜的光学性能研究

OPTICAL PROPERTIES OF NANO-CRYSTALLINE DIAMOND FILMS

用热丝化学气相(HFCVD)法在硅衬底上制备了表面光滑、晶粒致密均匀的纳米金刚石薄膜,用扫描电镜(SEM)和原子力显微镜(AFM)观测薄膜的表面形貌和粗糙度,拉曼光谱表征膜层结构,紫外-可见光分光光度计测量其光透过率,并用椭圆偏振仪测试、建模、拟合获得了表征薄膜光学性质的n,k值.结果表明薄膜的晶粒尺寸在100nm以下,表面粗糙度仅为21nm;厚度为3.26(m薄膜在632.8nm波长处的透过率为25%,1100nm波长处达到50%.采用直接光跃迁机制估算得到纳米金刚石薄膜的光学能隙(Eg)为4.3 eV.

A Nano-crystalline diamond film with a smooth surface and compact and uniform crystal grains was successfully deposited on silicon by HFCVD method. Scanning electron microscopy （SEM）, atom force microscopy （ AFM）, Raman scattering spectra, as well as optical transmission spectra and spectroscopic ellipsometry were employed to characterize the as-grown films. The calculated values of the optical constants n and k were obtained from the applied EMA model and fitted result. The surface roughness of the film is only 21nm, while its grain size is no more than 100nm. The optical transmission of the film, whose thickness is 3. 28μm, is close to 25 percent at the wavelength of 632.8nm and up to he 50percent at the wavelength of 1100nm. Its band gap is estimated to be 4.3ev by direct optical transition machanics.