INFLUENCE OF FILM THICKNESS AND ANNEALING TEMPERATURE ON OPTICAL PROPERTIES OF AMORPHOUS SILICON THIN FILMS

A detailed study of the dependence of optical constants on thickness and annealing temperature for vacuum-deposited amorphous silicon thin films is reported. The thicknesses of the films range from 75nm to 138nm. The samples morphological characterizations are done using XRD and SEM. optical constants such as refractive index n (λ), absorption coefficient α (λ), extinction coefficient k (λ) and consequently the optical band gap, are determined from the spectrophotometric measurements of the film transmittance in the wavelength range 400-2500 nm. RF sputtering was used to deposit all films with power (150w) the deposition temperature was 185 °C and the working pressure in the deposition -3 chamber was (7.2×10 mbar).