Thickness Dependency of Zinc Selenide (ZnSe) Thin Film Deposited By Vacuum Evaporation Method

Fabrication of Zinc Selenide (ZnSe) thin film having different thickness has been performed on glass substrate using thermal vacuum evaporation technique by evaporating ZnSe powder and is further characterized by X-ray diffractometer (XRD) and UV-VIS-NIR spectrophotometer. XRD patterns revealed that ZnSe thin film has face centered cubic (fcc) structure with variable miller indices at maximum X-ray intensity as the thickness changes. Substrate temperature is fixed at 290°C and all films are annealed for 60 minutes at 300°C. We have got peak value of intensity in XRD patterns which drops as the thickness of ZnSe thin film reduces. Optical properties like transmittance, refractive index, energy bandgap and reflectance have also been extracted in both simulation and experiment and found promising results. Transmittance in near-infrared region for all the films are greater than 63% in simulation and fewer less in experiment, variable reflectance of (7-31)%, optical bandgap from 2.44 eV to 2.64 eV and fluctuation in refractive index from 2.31 to 2.70 as the film thickness changes. Optical bandgap goes wider for higher thickness films and gets lower as the film thickness decreases.