溅射功率对InZnO薄膜晶体管电学性能的影响研究

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

采用射频磁控溅射法,在室温下Si/SiO_(2)衬底上制备InZnO薄膜晶体管,并研究不同溅射功率(25,50,75和100 W)对InZnO薄膜晶体管电学性能的影响。XRD表征结果表明,不同溅射功率制备的InZnO薄膜均出现晶面为(002)面的多晶态结构。通过电学特性研究发现,当溅射功率为50 W时,电流的开关比为3×10^(7),场效应迁移率为14.8 cm^(2)V^(-1)s^(-1),阈值电压为0.82 V,亚阈值摆幅为0.38 V decade^(-1),界面缺陷态密度为1.1×10^(12)cm^(-2)eV^(-1)等获得最佳器件参数。这是因为功率50 W时用原子力显微镜测得InZnO薄膜表面粗糙度为0.86 nm,说明薄膜的表面比较平滑,表面缺陷密度较少,使InZnO薄膜沟道层和源漏电极形成了良好的接触。此外,XPS结果表明,当溅射功率为50 W时,能够有效控制氧空位缺陷,最终有效改善和提高InZnO薄膜晶体管的电学性能。

InZnO thin film transistors(TFTs)were prepared by using the radio frequency magnetron sputtering method on the Si/SiO_(2)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 3×10^(7),a field effect mobility of 14.8 cm^(2)V^(−1)s^(−1),a threshold voltage of 0.82 V,a sub-threshold swing of 0.38 V decade^(−1),and an interface trap density of 1.1×10^(12)cm^(−2)eV^(−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.