Growth and characterization of undoped and indium doped zinc oxide thin films grown by hydrothermal method

Zinc oxide is a widely used semiconductor metal oxide in optoelectronic applications and it is very advantageous material for transparent conductive oxides (TCO). Recently, to investigate and enhance the properties of ZnO thin films, researchers have been carrying out many researches. In this study, undoped ZnO and indium doped ZnO (IZO) films with different indium percentages (1%, 3%, 5%, 7%) were produced by hydrothermal method on glass substrates. The influence of In doping on the structural, surface and optical properties of ZnO films were investigated. On the other hand, as the parameters of hydrothermal method; growth time, growth temperature effects on the properties of the ZnO and In doped ZnO film were analyzed. For this purpose, the growth time of ZnO films were changed as 3h, 5h, 7h, 9h and 24h. Also, growth temperatures were varied as 90℃, 120℃ and 150℃ too. After the film growth process X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Photoluminescence Spectroscopy (PL) and UV-VIS Spectroscopy measurements were carried out to characterize films' structural, optical, and surface properties. By these characterization methods, the best growth parameters of the films were decided. According to characterization results, all the ZnO and IZO films successfully were grown by hydrothermal method. Hexagonal wurtzite structure and well adhesion to substrate were observed. For the crystallite size, XRD intensity at preferred growth plane, dislocation density and microstrain, a good compromise was reached for 9h growth time, 3% In percentage, and 90°C growth temperature. From the PL, the lowest defect and highest crystallization quality were obtained for 3% In, 9h and 90°C films. As a result, for this work, 9 h growth time, 90°C growth temperature and 3% In doping concentration were defined as the best growth parameters.