Determination of the thickness and optical constants of transparent indium-doped ZnO thin films by the envelope method

Transparent indium-doped ZnO thin films were deposited by the spray pyrolysis method onto glass substrates. The content of indium in the starting solution was 0.5 at. %. The crystallographic structure of the film was studied by X-ray diffraction (XRD). XRD measurement shows that the film is crystallized in the wurtzite phase and presents a preferential orientation along the c-axis. The texture coefficient (TC), grain size value and lattice constants have been calculated. The absorption coefficient and the thickness of the films were calculated from interference of transmittance spectra. Optical constants such as the refractive index n and extinction coefficient k have been determined from transmittance spectrum in the ultraviolet–visible–near infrared (UV–VIS–NIR) regions using the envelope method. The thickness of the films strongly influences the optical constants.