Spectroscopic study on the influence of post-processing annealing on ZnO films produced with a sol-gel method

Zinc oxide is still one of the most crucial wide bandgap semiconductors for electronics. It is highly used because of its ease of production, doping, and low cost. However, in the production of zinc oxide materials, it is necessary to consider the formation of native defects, which strongly influence the material's properties. Therefore, it is essential to understand the behavior in thin films during the annealing process. The presented work shows the appearance of oxygen and zinc vacancies during annealing at specific temperatures and times. Samples annealed in an oxygen-rich atmosphere change their structural and chemical properties. Specific defects may be detected using Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. In addition, energy bandgap, defects energy, and the thermal dependence of luminescence emission were analyzed as the primary indicators of the changes during the sintering.