Effect of Indium Doping on Optical Parameter Properties of Sol-Gel-Derived ZnO Thin Films

Zinc oxide (ZnO) has gained great interest for two decades, and its structural, optical, and electrical properties have been investigated by scientists for technological applications. The optical properties of ZnO provide an opportunity for its application in solar cells, lasers, and light-emitting diodes. We prepared ZnO thin films with various In doping levels by using a spin coating technique, and characterised their morphological and detailed optical properties for optical applications. According to the morphological properties obtained by atomic force microscopy, the film surfaces are homogeneous and the In doping level affects the surface morphology of the films. The optical properties of the films were investigated using an ultraviolet-visible spectrometer, and some optical parameters such as band gap, refractive index, extinction coefficient, single oscillator parameters, real and imaginary functions of the dielectric coefficient, and optical conductivity were calculated and discussed in detail. The various In doping levels affected the optical properties, and the In-doped ZnO thin films can find applications in industry.