Effect of thickness on characteristics of ZnSe thin film synthesized by vacuum thermal evaporation

AbstractZinc selenide (ZnSe) thin films with various thicknesses were grown on ultrasonically clean glass substrates using vacuum evaporation of ۹۹.۹۹% pure ZnSe powder. Thickness dependence of the structural, optical and electrical properties was thoroughly investigated. X-ray diffraction (XRD) analyses revealed that (۱۱۰) ZnSe plane is the dominant crystal plane for all the fabricated films. Both dislocation density and micro-strain go down with the increase in film thickness, indicating lower lattice defects and improvement in crystallinity at higher film thickness. Transmittance spectra show that all the films have almost linear upward tendency of transmittance in near-infrared region and small fluctuations in visible region for higher-thickness films. With the increase in film thickness, the optical bandgap increases and also an increasing tendency of dielectric constant was observed. Studies of electrical properties showed a sharp increase in carrier mobility and concentration with film thickness. As the film thickness increases from ۳۰ to ۹۰ nm, the carrier mobility goes up from ۲۵۵ to ۱۲۵۰ cm۲/VS and the carrier concentration increases from ۲.۱۴ × ۱۰۱۸ to ۹.۳۷ × ۱۰۱۸ cm−۳. The electrical transport properties of the deposited thin films were explained in terms of scattering of the charge carrier.

کلیدواژه ها:

ZnSe thin film ، Vacuum thermal evaporation ، x ، ray diffraction ، UV–Vis–NIR spectrophotometer ، Hall effect measurement