Preparation, structure and optical properties of transparent conducting gallium-doped zinc oxide thin films

Abstract

Highly conductive gallium-doped zinc oxide (GZO) transparent thin films were deposited on glass substrates by RF magnetron sputtering. The deposited films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), four-point probe and UV-Vis spectrophotometer, respectively. The effect of growth temperature on the structure and optoelectrical properties of the films was investigated. The results demonstrate that high quality GZO films oriented with their crystallographic c-axis perpendicular to the substrates are obtained. The structure and optoelectrical properties of the films are highly dependent on the growth temperature. It is found that with increasing growth temperature, the average visible transmittance of the deposited films is enhanced and the residual stress in the thin films is obviously relaxed. The GZO films deposited at the growth temperature of 400°C, which have the largest grain size (74.3 nm), the lowest electrical resistivity (1.31 × 10 −3 Ω·cm) and the maximum figure of merit (1.46 × 10 −2 Ω −1 ), exhibit the best optoelectrical properties. Furthermore, the optical properties of the deposited films were determined by the optical characterization methods and the optical energy-gaps were evaluated by extrapolation method. A blue shift of the optical energy gap is observed with an increase in the growth temperature.

Study of Sputtered ZnO:Ga2O3 Films for Energy Harvesting Applications

“…With the development of the energy harvesting market, ZGO films are necessary to be implemented in flexible nanogenerator devices, requiring cyclic applied continuous mechanical loading with low frequency. However, the available studies reveal data mostly about the material conductivity and optical and gas sensing properties of ZGO and less about the piezoelectric response and its dimensions in sputtering growth conditions [9,10]. In fact, the sputtering conditions influencing the roughness, have a great effect on the piezoelectric device's electrical contact, although the nanometric scale of the roughness [11].…”