室温下溅射法制备高迁移率氧化锌薄膜晶体管

为降低氧化锌薄膜晶体管(ZnO TFT)的工作电压,提高迁移率,采用磁控溅射法在氧化铟锡(ITO)导电玻璃基底上室温下依次沉积NbLaO栅介质层和ZnO半导体有源层,制备出ZnO TFT,对器件的电特性进行了表征。该ZnO TFT呈现出优异的器件性能:当栅电压为5 V、漏源电压为10 V时,器件的饱和漏电流高达2.2 m A;有效场效应饱和迁移率高达107 cm~2/(V·s),是目前所报道的室温下溅射法制备ZnO TFT的最高值,亚阈值摆幅为0.28 V/decade,开关电流比大于107。利用原子力显微镜(AFM)对NbLaO和ZnO薄膜的表面形貌进行了分析,分析了器件的低频噪声特性,对器件呈现高迁移率、低亚阈值摆幅以及迟滞现象的机理进行了讨论。

High Mobility ZnO Thin-film Transistor Fabricated by Sputtering at Room Temperature

In order to reduce the operating voltage and increase the carrier mobility in zinc oxide thin-film transistor (ZnO TFT), ZnO TFTs with high-k NbLaO as gate dielectric layer were fabricated on indium tin oxide/glass substrate by radio-frequency magnetron sputtering at room temperature, and the electrical properties of the device were characterized. The fabricated ZnO TFTs exhibit excellent device performances. The saturation drain current can reach to 2.2 mA at gate voltage of 5 V and drain voltage of 10 V. The saturation mobility increases drastically up to 107 cm²/(V·s), which is one of the highest field-effect mobility values achieved in ZnO-based TFTs by room-temperature sputtering. The subthreshold swing and on-off current ratio are 0.28 V/decade and higher than 10⁷, respectively. The relative mechanisms of high mobility, small subthreshold voltage swing and hysteresis phenomenon are discussed by analyzing the atom force microscope images of the NbLaO dielectric and ZnO active-layer film, and the low frequency noise behavior of the device.