The Influence of Sputtering Power on the Electrical Properties of InZnO Thin-Film Transistors

InZnO thin film transistors (TFTs) were prepared by using the radio frequency magnetron sputtering method on the Si/SiO₂ substrates at room temperature. Effects of different sputtering powers (25, 50, 75, and 100 W) on the electrical properties of InZnO TFTs were studied systematically. XRD experimental results show that the InZnO thin film is a poly-crystalline structure with the growth crystal plane of the (002) face. Based on the electrical characterization, it has been found that when the sputtering power is 50 W, the optimal device parameters such as a current on-to-off ratio of 3×10⁷, a field effect mobility of 14.8 cm²V⁻¹s⁻¹, a threshold voltage of 0.82 V, a sub-threshold swing of 0.38 V decade⁻¹, and an interface trap density of 1.1×10¹² cm⁻²eV⁻¹ were obtained. This is because the surface roughness of the InZnO film measured by atomic force microscopy (AFM) at 50 W power is 0.86 nm, which indicates that the surface of the film is relatively smooth, reducing surface defects and making the channel layer of the InZnO film form a good contact with the source and drain electrodes. In addition, XPS results indicate that when the sputtering power is 50 W, oxygen vacancy defects can be effectively controlled, resulting in improving the electrical performance of InZnO TFTs.