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

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,5×103 and 0.61cm2/(V·s),respectively.The SiO2,Al2O3,SiNx,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.