Improved electrical and optical properties of GZO films with a thin TiO2 buffer layer deposited by RF magnetron sputtering

Ga-doped ZnO (GZO) thin films were prepared by radio frequency magnetron sputtering without intentional substrate heating on bare glass and TiO2-deposited glass substrates to investigate the effect of a thin TiO2 buffer layer on the optical and electrical properties of the films. The thicknesses of the TiO2 buffer layer and GZO films were kept constant at 5 and 100 nm, respectively. As-deposited GZO/TiO2 bi-layered films show a higher transmittance of 83.0% than that of the GZO films, and GZO/TiO2 films show a lower resistivity (1.03×10−2 Ω cm) than that of the GZO single layer films. In addition, the work function of the GZO film was affected by the TiO2 buffer layer, where the GZO/TiO2 films had a higher work-function (4.86 eV) than that of the GZO single layer films. The experimental results indicate that a 5-nm-thick TiO2 buffer layer in the GZO/TiO2 films results in better electrical and optical performance than conventional GZO single layer films.