Structural, optical and electrical properties of undoped and indium doped zinc oxide prepared by spray pyrolysis

Thin films of transparent undoped and indium doped ZnO have been deposited using the spray pyrolysis technique. The structural, optical properties and electrical resistivity of these films are investigated as a function of substrate temperature and indium concentration in the solution. X-ray diffraction showed that the films prepared at substrate temperature greater than 300 °C exhibit the hexagonal wurtzite structure with a preferential orientation along the (002) direction. Indium doping changes the orientation of grains to the (110) direction. This result is confirmed by SEM. The composition of the films is also examined by XPS. High transmittance (80%) in the visible region and low resistivity of about 10-1 Ω.cm at room temperature are obtained for thin films prepared under optimum deposition conditions: Ts = 450 ○C and In/Zn = 2 at.%