Synthesis and Non-Destructive Characterization of Zinc Selenide Thin Films

The present work encloses the deposition of three zinc selenide (ZnSe) thin films of thickness 175 nm, 243 nm, and 286 nm using thermal evaporation technique under a vacuum of 5 x 10(-5) mbar. The deposited ZnSe thin films are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), surface profilometer, ultraviolet (UV)-visible (Vis)-near-infrared (NIR) spectrophotometer and Raman spectroscopic measurements. The structure and morphology measurements reveal that the deposited ZnSe material is nanocrystalline having a cubic structure whose crystallinity increases with an increase in film thickness/evaporation rate. The optical band gap estimated from the optical transmission spectra of the films is found to be 2.62 eV, 2.60 eV, and 2.57 eV, respectively, which decreases with an increase in film thickness. The estimation and polynomial curve fit analysis of refractive index, extinction coefficient, and dielectric constant indicates that these physical quantities are fifth-order polynomial function of wavelength. The obtained results are compared and analysed for justification and application of ZnSe thin films.