Magnetron-sputtered gallium–magnesium–zinc oxide transparent semiconductor thin films: Structural, optical and electrical investigation

Abstract

Thin transparent semiconductor films of gallium–magnesium–zinc oxide (GaMgZnO) have been prepared with magnetron-sputtering technique on quartz glass substrates. We have investigated the effects of sputtering pressure on the crystallization, micro-structure, electrical and optical features of the deposited films. The results indicated that all the deposited films were polycrystalline in nature having a hexagonal wurtzite-type crystal structure with a preferred grain orientation in the (002) direction. The sputtering pressure has a significant impact on the structure and electro-optical characteristics of the deposited films. The sample prepared under sputtering pressure of 3.6 Pa possesses the best crystalline quality and electro-optical performance, with the minimum dislocation density (3.69×1014linesm−2), tensile stress (8.26×107 Pa), resistivity (1.53×10−3Ωcm), the maximum mean visible transmittance (87.71%) and the highest figure of merit (4.73×103Ω−1cm−1). Additionally, the external extrapolation method is employed to evaluate the optical band gap. The gap value is between 3.41 and 3.44 eV, which is larger than the optical band gap of pure ZnO.