Transparent conducting undoped and indium-doped zinc oxide films prepared by spray pyrolysis

Undoped and indium-doped ZnO thin films are deposited by the spray pyrolysis process onto glass substrates. The effects of starting solution composition and indium doping on the structural, electrical, and optical properties are investigated. The surface morphology of the deposited films is a strong function of the source compounds. Thus two distinct morphologies with large difference in the average grain size are obtained by using separately zinc chloride and zinc acetate. The polycrystalline nature with no second phases is observed by X-ray diffraction. Indium doping leads to a very low resistivity of about 10−3 Ω cm. High transparency of the films, more than 85% in the visible range, is observed.