Effect of thickness on the structural, optical and electrical properties of RF magnetron sputtered GZO thin films

Gallium-doped zinc oxide (GZO) thin films with very high conductivity and transparency were successfully deposited by RF magnetron sputtering at a substrate temperature of 400 °C. The dependence of the film properties over the thickness was investigated. X-ray diffraction (XRD) results revealed the polycrystalline nature of the films with hexagonal wurtzite structure having preferential orientation along [001] direction normal to the substrate. The lowest resistivity obtained from electrical studies was 5.4×10−4 Ω cm. The optical properties were studied using a UV–vis spectrophotometer and the average transmittance in the visible region (400–700 nm) was found to be 92%, relative to the transmittance of a soda–lime glass reference for a GZO film of thickness 495 nm and also the transparency of the films decreases in the near IR region of the spectra. The mobility of the films showed a linear dependence with crystallite size. GZO film of thickness 495 nm with the highest figure of merit indicates that the GZO film is suitable as an ideal transparent conducting oxide (TCO) material for solar cell applications.