Structural and Optical Properties of Polycrystalline Silicon Thin Films Deposited by the Plasma Enhanced Chemical Vapour Deposition Method

Polycrystalline silicon (Si) films have been deposited on both Si and foreign substrates by the plasma enhanced chemical vapour deposition (PECVD) method. Structural properties of Si films were characterised by X-ray diffraction (XRD) and Raman scattering measurements. These films show (110) preferred orientation. Their optical properties were measured by a spectrophotometer over the wavelength range 0.4 to 1.2 µ m. Optical constants of Si films were calculated using the optical admittance method. The crystallinity of the films prepared at different temperatures is investigated by Raman scattering measurements and the two-phase mixture approximation. Results reveal that over 90% of the Si was in a polycrystalline structure in the films when the deposition temperature was over 800° C.