Optoelectronic properties of ZnO:In thin films by ultrasonic spray pyrolysis

Transparent and conductive Indium-doped zinc oxide (ZnO:In) thin films were deposited on glass substrates by the ultrasonic spray pyrolysis technique. ZnO:In thin films were prepared by mixing 0.2M zinc acetate and 0.2M indium sulphate dissolved in a mixture of water, acetic acid and methanol. Indium sulphate which acts as the In source was chosen at three different atomic concentrations, namely, 1, 2, and 3 at. % and the films were deposited at a temperature ranging between 385 °C and 430 °C. The dependence of the electrical and optical properties on the substrate temperature and the dopant concentration was studied. Electrical resistivity as low as 1.6×10^-3 Ωcm, electron mobility around 11 cm²/(V-s), carrier concentration in the range 4.96-8.98 ×10²⁰ cm^-3, and an optical transmittance of about 80 % was achieved for 3 at. % ZnO:In thin films.