Electrical and optical properties of ZnO transparent conducting films by the sol–gel method

Abstract

The effect of drying conditions and the first- and second-heat treatment on the structural, electrical and optical properties of ZnO thin films prepared by the sol–gel method was investigated. ZnO films were deposited on silica glass substrates by the spin-coating method. Zinc acetate dihydrate, 2-methoxyethanol and monoethanolamine were used as a starting material, solvent and stabilizer, respectively. ZnO films were dried at 350°C and then heated at 600°C showed an extremely sharp (0 0 2) peak in the XRD patterns. The more films were oriented preferentially along (0 0 2) direction, the greater their electrical and optical properties became. By applying the second-heat treatment in nitrogen with 5% hydrogen at 500°C, the grain size of films was increased, the resistivity value was 0.099 Ω cm and optical transmittances became higher than 85% in the visible range.