Effects of gate work function on E-mode AlGaN/GaN HEMTs with stack gate β-Ga2O3/p-GaN structure

This research investigates electrical properties of E-mode AlGaN/GaN HEMTs with n-type beta-Ga2O3/p-GaN gate stack under different gate work functions of 4.6, 5.1 and 5.7 eV, respectively. The simulated results show that the device with gate work function of 5.7 eV exhibits the largest threshold voltage of 2.8 V while having the lowest saturation drain current of 0.15 A mm(-1), which can be ascribed to the device having the highest Schottky barrier, leading to the least electrons collected at the AlGaN/GaN interface. Moreover, the device with gate work function of 5.7 eV shows the largest gate breakdown voltage as well as the lowest off-state gate leakage, which can be attributed to the least strength of electric field in the Ga2O3 layer. Additionally, the Fowler-Nordheim equation was used to study the mechanisms of off-state leakage.