以ZnO为沟道层的薄膜晶体管制备研究

The fabrication of thin film transistors with ZnO as active channel layer

采用光刻剥离工艺和射频磁控溅射法分别在(100)硅片和ITO玻璃衬底上制备了以氧化锌为沟道层的底栅式薄膜晶体管(ZnO-TFT)。用X射线衍射仪、原子力显微镜对生长在绝缘层上的ZnO薄膜进行了表征。在硅衬底ZnO-TFT中,热氧化生长的二氧化硅薄膜作为绝缘层,金属铝用作源漏电极,该器件工作在N沟道增强模式,其阈值电压为8V,电流开关比为5×103,电子的场迁移率达到0.61cm2/(V.s)。在以ITO玻璃为衬底的透明ZnO-TFT中,分别采用了SiO2、Al2O3、SiNx、PbTiO3薄膜作为绝缘层,实验表明生长在不同绝缘层上的ZnO薄膜都有很高的c轴择优取向,透明ZnO-TFT在可见光波段的平均透过率达到85%。

Bottom-gate thin film transistors with ZnO as the active channel layer were fabricated on （100） silicon wafer or ITO glass by lift-off and rf sputtering method. The ZnO films deposited on insulator layer were characterized by X-ray diffractometry and atomic force microscopy. Thermally oxidized SiO2 film was served as insulator in ZnO-TFT fabricated on silicon wafer,and aluminum metal was used for source and drain contacts. The device operated in n channel enhancement mode with the threshold voltage,current on/off ratio, channel mobility of 8V,5 × 10^3 and 0. 61cm^2/（V · s） ,respectively. The SiO2 ,Al2O3 ,SiN2 ,PbTiO3 films were used as gate insulators in transparent ZnO-TFTs fabricated on ITO glass. It was found that the ZnO films all have high c-axis preferential orientation on different insulators and the average optical transmittance of transparent ZnO-TFTs was 85% approximately.