Improvement of Mobility in ZnO Thin Film Transistor with an Oxygen Enriched MgO Gate Dielectric

The performance of bottom-gate ZnO thin film transistors (TFTs) using MgO gate dielectrics evaporated with and without introducing oxygen have been investigated. The oxygen introduced during MgO deposition improves the field-effect mobility significantly as compared to the device without introducing oxygen during MgO deposition. The oxygen-introduced MgO exhibits a dielectric constant of 10.9 and the field-effect mobility of the TFT device is enhanced to 78.3 cm 2 /V s. The threshold voltages can also be related to whether the oxygen is introduced into MgO or not. The interface between oxygen-introduced MgO and ZnO is examined and its connection with mobility enhancement is discussed.