E-mode p-channel GaN/AlGaN HFETs with κ-Ga2O3 as gate oxide

In this article, a κ-Ga₂O₃ cap layer is introduced as gate dielectric to achieve E-mode GaN p-channel heterostructure FETs (p-HFETs). Due to the high spontaneous polarization of κ-Ga₂O₃, 2DEG that up to 1.51 × 10¹⁴ cm^− 2 are induced at the κ-Ga₂O₃/GaN interface. Based on device simulations, the threshold voltage (V_TH) can reach a high value of -2.42 V and maintain negative even when the thickness of the GaN channel (t_ch) is increased to 50 nm. By interconnecting base and gate to form a double-gate (DG) structure, the control of 2DEG and 2DHG can be realized. The results show that p-HFETs with DG structure not only exhibit a threefold increase in the on-current (I_ON) while maintaining the E-mode operation, reaching 24.87 mA/mm with V_TH of -1.25 V, but also reduce the gate leakage current at forward bias. Furthermore, the utilization of κ-Ga₂O₃ as the gate dielectric results in an enhancement of the gate breakdown voltage to -35.8 V. The proposed DG p-HFETs represent a promising approach to achieving high-performance enhancement mode p-channel GaN devices.