Abstract: Top-contact thin film transistors (TFTs) using radio frequency (RF) magnetron sputtering zinc oxide (ZnO) and silicon dioxide (SiO₂/ films as the active channel layer and gate insulator layer, respectively, were fabricated. The performances of ZnO TFTs with different ZnO film deposition temperatures (room temperature, 100oC and 200oC) were investigated. Compared with the transistor with room-temperature deposited ZnO films, the mobility of the device fabricated at 200oC is improved by 94% and the threshold voltage shift is reduced from 18 to 3 V (after 1 h positive gate voltage stress). Experimental results indicate that substrate temperature plays an important role in enhancing the field effect mobility, sharping the subthreshold swing and improving the bias stability of the devices. Atomic force microscopy was used to investigate the ZnO film properties. The reasons for the device performance improvement are discussed.

Key words: ZnO-TFT