Influence of post-annealing condition on the properties of ZnO films

The study of the properties of zinc oxide (ZnO) films has gained popularity recently due to its potential in a wide range of applications, such as thin-film solar cells, transistors, sensors and other optoelectronic devices. In this work, low cost sol–gel spin coating technique was employed to fabricate the ZnO films. The influences of post-annealing condition on the properties of the ZnO films were investigated. The ZnO films were annealed under ambient, nitrogen and vacuum environments at 450 °C and the environment effects on the ZnO films were compared. Furthermore, the effect of cooling period allowed for the ZnO films after the post-annealing process was examined. The ZnO films were characterized using surface profilometer, atomic force microscopy, X-ray diffractometer, and ultraviolet–visible transmission spectroscopy in order to study the thickness, surface morphology, crystallinity, and optical properties of the ZnO films. The optical band gap of the ZnO films was estimated based on the thickness and the optical transmittance data. These investigations serve to clarify the effects of different post-annealing conditions in order to optimize the properties of the ZnO films.