Characteristics of Al-doped c-axis orientation ZnO thin films prepared by the sol–gel method

Transparent conducting ZnO thin films doped with Al have been prepared by sol–gel method, which were characterized by X-ray diffraction, atomic force microscopy and ultra-violet spectrometer. The films showed a hexagonal wurtzite structure and high preferential c-axis orientation. The optical transmittance spectra of the films showed the transmittance higher than 85% within the visible wavelength region. A minimum resistivity of 6.2 × 10−4 Ω cm was obtained for the film doped with 1.5 mol.% Al, preheated at 300 °C for 15 min and post-heated at 530 °C for 1 h.