7.6 V Threshold Voltage High-Performance Normally-Off Al2O3/GaN MOSFET Achieved by Interface Charge Engineering

An efficient approach to engineering the Al2O3/GaN positive interface fixed charges by post-dielectric annealing in nitrogen is demonstrated. The remarkable reduction of interface fixed charges from 1.44 × 1013to 3 × 1012cm-2was observed, which leads to a record high threshold voltage (VTH) of 7.6 V obtained in the Al2O3/GaN MOSFETs. The significantly reduced interface fixed charges and the corresponding remote scattering effect enable respectable improvement in the electron mobility that results in a high drain current density of 355 mA/mm in the device. These competitive results reveal that the method reported in this letter is promising in pushing VTHmore positive and simultaneously achieving good device performance of normally-off GaN power devices.