Substrate temperature effects on the structural and optical properties of Tio₂-doped ZnO films for organic photovoltaic devices

Tio₂-doped ZnO thin films with highly (002)-preferred orientation were grown on glass substrates by RF magnetron sputtering. The effect of substrate temperature on structure and optical properties of the films were investigated by X-ray diffractometer and spectrophotometer. The results show that the polycrystalline Tio₂-doped ZnO films consist of the hexagonal crystal structures with c-axis as the preferred growth orientation normal to the substrate. The substrate temperature significantly affects the crystallite size and optical transmittance of the deposited films, but slightly influences the refractive index and optical bandgap of the deposited films. The Tio₂-doped ZnO film grown at substrate temperature of 470 K possesses the maximum crystallite size, an average transmittance of 76.2% in the visible light range, and an optical bandgap of 3.46 eV.