Substitution of an isovalent Te-ion in SnSe thin films for tuning optoelectrical properties

Abstract

In present work, SnSe_1-xTe_x thin films with varying Te concentrations were deposited on glass substrate through thermal evaporation technique. SnSe_1-xTe_x thin films were characterized using X-ray diffraction (XRD), atomic force microcopy (AFM), X-ray photoelectron spectroscopy (XPS), UV–Vis NIR spectroscopy and room-temperature hall measurements technique. XRD patterns revealed that all the samples had a polycrystalline orthorhombic structure. Additionally, a low level of Te impurity improved the crystalline quality of the SnSe thin films. AFM images showed a noticeable alteration in the surface structure of the SnSe thin films caused by Te doping. UV–Vis NIR spectroscopy was employed to assess the optical characteristics of SnSe_1-xTe_x thin films, revealing a variation in the optical band gap energy (E_g) between 1.75 and 1.89 eV, attributed to Te doping. The Hall effect measurement revealed n-type conductivity, and the carrier concentration decreased as the Te dopant concentration increased, corresponding to a decrease in antisite SnSe defects. The experimental findings suggest that adding a moderate amount of Te is a beneficial method for enhancing the optical and electrical properties of SnSe films. Furthermore, the Schottky device parameters of the Ag/SnSe_1-xTe_x/Al:ZnO structure were established by analyzing the temperature-dependent Current-Voltage (I–V-T) characteristics through the thermionic emission current transport mechanism.