Threshold Voltage Control of Amorphous Gallium Indium Zinc Oxide TFTs by Suppressing Back-Channel Current

Effects of plasma treatments on the back-channel of amorphous Ga(2)O(3)-In(2)O(3)-ZnO (GIZO) thin film transistors (TFTs) are compared for N(2) and N(2)O plasma. Acceptor-like states originating from the oxygen adsorbed on the back-channel of the GIZO TFTs suppress the back-channel current by capturing the electrons in the GIZO active layer and thus shift the threshold voltage to the positive direction. It is also shown that the oxygen in a silicon oxide passivation layer reduces the back-channel current. An enhancement-mode GIZO TFT has been successfully fabricated by combining the N(2)O plasma treatment and the silicon oxide passivation layer.