Effect of Annealing Temperatures and Pre-Heating on the Characteristics of a Nanocrystalline ZnO Thin Film Prepared by the Sol-Gel Dip-Coating Method

For effectively fabricating nanocrystalline ZnO thin films by the sol-gel method, the relationships between the temperature of the heat treatment and the quality of the ZnO thin films was observed. The decomposition of the sol was analyzed by TG-DTA. The orientation of the c-axis of the ZnO thin film was identified by XRD. The morphology was observed and estimated by SEM. The experimental results did show that the orientation of the c-axis is determined by the pre-heating and annealing temperatures, and that the grain size and roughness of the ZnO thin films are mainly influenced by the annealing temperature. A qualified ZnO thin film was prepared by using a sol-gel with a preheating temperature of 275 ◦C for 10 min and an annealing temperature of 550 ◦C for 60 min.