Substrate Temperature Impact on the Structural, Optical and Photo-Catalytic Activity of Sputtered Cu-Doped ZnO Thin Films

Abstract

Herein, I describe a study on the impact of substrate temperature on the structural, optical and photo-catalytic activity of sputtered Cu-doped ZnO thin films. Cu-doped ZnO nanocrystalline thin films of 10 wt.% Cu were first prepared at different substrate temperatures by radio frequency magnetron sputtering. Energy-dispersive X-ray spectroscopy was used to verify the percentage of Cu-doping. Both the structural and optical changes for the deposited thin films were measured by different characterization techniques. The nature of the deposited films was measured by X-ray diffraction analysis (XRD) that showed four characteristic peaks (002), (103), (100), and (111) related to ZnO. The intensity of the XRD peaks was affected by Cu-doping and increasing the substrate temperatures. The surface morphology and roughness for the prepared thin films were measured by atomic force microscopy. The calculated optical band gap of the prepared thin films deceased from 3.16 eV for the pure ZnO to 2.74 eV, 2.71 eV, 2.69 eV and 2.66 eV for the 10 wt.% Cu-doped ZnO thin film deposited at room temperature, 100°C, 200°C, and 300°C, respectively. The photoluminescence (PL) spectra for the prepared thin films were recorded to examine the impact of Cu-doping and the effect of increasing the substrate temperatures. As a photo-catalyst, the deposited thin films demonstrated high efficiency and stability concerning the degradation of methylene blue organic dye under a 500 W visible lamp and reusability for photo-catalytic experiments without much loss.