Optical and electrical properties of room temperature prepared α-IGZO thin films using an In2Ga2ZnO7 ceramic target

In this study, a high-purity In2Ga2ZnO7 ceramic target was used to deposit indium gallium zinc oxide (IGZO) films by RF magnetron sputtering technology. The microstructure, growth state, optical and electrical properties of the IGZO films were studied. The results showed that the surface of the IGZO film was uniform and smooth at room temperature. As the substrate temperature increased, the surface roughness of the film gradually increased. From room temperature to 300 degrees C, all the films maintained amorphous phase and good thermal stabilities. Moreover, the transmission in the visible region decreased from 91.93% to 91.08%, and the band gap slightly decreased from 3.79 to 3.76 eV. The characterization of the film via atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS) demonstrated that the film prepared at room temperature exhibited the lowest surface roughness and the largest content of oxygen vacancies. With the rise in temperature, the non-homogeneous particle distribution, increase in the surface roughness, and reduction in the number of oxygen vacancies resulted in lower performance of the alpha-IGZO film. Comprehensive analysis showed that the best optical and electrical properties can be obtained by depositing IGZO films at room temperature, which indicates their potential applications in flexible substrates.