Electrical Properties in Group IV Elements-Doped ZnO Thin-Film Transistors

The group IV elements doped ZnO thin-film transistors (TFTs) were deposited by radio-frequency magnetron sputtering on SiO2/Si substrates at 150
^°
C. The influence of the dopant concentrations on the device performance was examined. Device characteristics such as threshold voltage (VTH) were modulated and field effect mobility and saturated current could be enhanced by tuning dopant concentration. Moreover, the negative bias stress was applied so that the reliability of the TFTs could be evaluated, the shift of VTH for Ge-doped TFTs is smaller than that of other TFTs, and therefore, Ge doping may help to improve the bias stability of ZnO TFTs.