Transparent conducting ZnO:Al, In and Sn thin films deposited by the sol-gel method

The effects of aluminum, indium and tin dopants on the microstructure and electrical properties of ZnO thin films prepared on silica glass substrates by the sol-gel method were investigated. As a starting material, zinc acetate dihydrate was used. 2-methoxyethanol and monoethanolamine were used as the solvent and stabilizer, respectively. The dopant sources were aluminum chloride, indium chloride and tin chloride. For each dopant, films doped with I at.% aluminum, I at.% indium and 2 at.% tin concentrations exhibited a stronger c-axis orientation perpendicular to the substrate and had larger grain, a high smooth surface morphology as well as high conductivity and transmittance than the others. In addition, the electrical resistivity value of ZnO thin films reduced by applying the second heat-treatment in nitrogen with 5% hydrogen. When the aluminum doping concentration was I at.%, the film had a columnar structure, a resistivity value of 1.1 X 10(-2) Omega cm and a transmittance higher than 90% in the visible spectra region. (C) 2003 Elsevier Science B.V. All rights reserved.