Ellipsometric analysis and optical absorption characterization of nano-crystalline diamond film
(1.School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China2.Physics Department, Mudanjiang Normal College, Mudanjiang 157012, China)
Abstract: A nano-crystalline diamond (NCD) film with a smooth surface was successfully deposited on silicon by a hot filament chemical vapor deposition (HFCVD) method. Scanning electron microscopy (SEM), atomic force microscopy (AFM), RAMAN scattering spectra, as well as spectroscopic ellipsometry were employed to characterize the as-grown film. By fitting the spectroscopic ellipsometric data in the energy range of 0.75？1.50 eV with a three-layer model, Si|diamond+non-diamond|diamond+non-diamond+void|air, the optical constants are obtained. The refractive index of the NCD film varies little from 2.361 to 2.366 and the extinction coefficient is of the order of 10？2. According to the optical transmittance and absorption coefficient in the wavelength range from 200 to 1 100 nm, the optical gap of the film is estimated to be 4.3 eV by a direct optical transition mechanics.
Key words: nano-crystalline diamond film; optical absorption; chemical vapor deposition