Growth mechanism and characterization of ZnO: Al multi-layered thin films by sol–gel technique

In this study, transparent conductive Al-doped ZnO films were deposited by the sol–gel method. The growth mechanism of the film microstructure and its influences on the electrical properties were discussed. It was found that dopant and solution concentration affected the nucleation behavior considerably. The preferred growth orientation of ZnO crystallite was restrained by the film itself. The repeated dip-coating processes did not enable the crystallite size to grow obviously, but it could allow crystallite and atoms to find the suitable positions and therefore led to a better film quality. Consequently, this process led to an electrical resistivity of 7.08 × 10− 3 Ω cm and a high transmittance of over 80% in the visible region. The best sample was obtained for an Al concentration of 1 at.% and at 600 °C for pre- and post-heat treatment.