Determination of The Thickness and Optical Constants of Polycrystalline SnO_2 Thin Film by Envelope Method

SnO2 (tin dioxide) thin film was deposited on commercial glass substrate by spray pyrolysis technique at 420oC. The XRD analyses indicated that the SnO2 thin film is found to tetragonal rutile structure. Optical transmission values (T %) of the film are the range of 80-96 % in the visible region and its highly transparent. The absorption coefficients (α) were defined from transmission spectrum. Refractive indices (n) and film thickness (t) were determined from interferences of the optical transmission curve with envelope method. The refractive indices (n) were altered between 1.83-1.97 in the ultraviolet-visible-near-infrared (UV-VIS-NIR) regions. The thickness (t) and optical energy gap (Eg) of the SnO2 thin film were found to be 1.22 μm and 3.98 eV, respectively