Synthesis and characterization of ZnO/ZnAl2O4/Zn2TiO4 composite films by Ar–O2 mixture hollow cathode glow discharge

In this study, ZnO/ZnAl2O4/Zn2TiO4 composite nanostructured thin films are deposited assisted with hollow-cathode glow discharge (HCD). The films are deposited using various argon-oxygen gases mixture (0–50% O2), and its effect on film quality, optical and electrical properties is examined. Remarkably, instead of metallic targets, ZnO, TiO2, and Al2O3 powders filled in hollow-cathode are used for deposition, and thus no specific metallic targets are required in this technique. The deposited films consist of hexagonal wurtzite ZnO structure, ZnAl2O4, and Zn2TiO4 phases, and the crystalline size of films increases for higher oxygen contents. The thickness of films reduced by increasing oxygen contents, and all deposited films exhibit transmittance higher than 82%. The carrier concentration and mobility increase, whereas resistivity decreases when a higher amount of oxygen is added. This study shows that HCD can effectively synthesize the composite film with good optical and electrical properties. Additionally, the film's properties and elemental composition can be tuned by changing the gas composition, and thus, no separate target metallic materials with the specific composition are required.