Microstructure, optical and electrical properties of gallium-doped ZnO films prepared by sol–gel method

•We study the influence of viscosity of the solutions on optoelectrical properties of GZO films.•Viscosity gel have significant effect on microstructure of GZO films.•Optimized gel’s viscosity can obtain the lower resistivity of GZO films. Gallium doped zinc oxide (GZO) films were deposited by dip-coating technique with different viscosity sols. The effect of the sols viscosity on the microstructure, optical and electrical properties of the GZO films was investigated. The GZO films were polycrystalline with hexagonal structure. The root mean square roughness (Rms) of the GZO films increased with the increase of the sols’ viscosity. When the viscosity reached 2.7cps, GZO films with the resistivity of 1.9×10−2Ωcm and the hall mobility of 32cm2V−1s−1 were obtained. Several crack and mountain-like structure appeared on the surface of GZO films fabricated with 3.0cps sol. The transmittance of all the GZO films was higher than 80% in visible range except for GZO films prepared with 3.0cps sol.