A normally-off hybrid-gate p-GaN high-electron-mobility transistor (HEMT) is presented in this paper. The gate region is designed as a parallel connection between the Schottky-gate and the metal–insulator–semiconductor gate by inserting a dielectric layer under part of the gate metal. Compared to the conventional Schottky-gate p-GaN HEMT, the fabricated hybrid-gate p-GaN HEMT showed a higher threshold voltage of 3.2 V (increases by 167%), and the maximum transconductance is only a slight decrease (reduces by 23%). At the same time, the forward gate leakage current of the hybrid-gate structure is smaller. Furthermore, through simulation, we revealed that the increase in the threshold voltage originated from the delayed full opening of the two-dimensional electron gas. And we also find that the parameters of the gate dielectric layer have a great influence on the performance of the device. The results show that the hybrid-gate structure is a more promising device structure.

Beta-gallium oxide (β-Ga2O3) devices exhibit the degradation of on-state characteristics compared with the theoretical expectation according the recent reports. Simulation of electrical properties in devices should, therefore, include model calibration valid up to such situation. In this paper, the anisotropic mobility modeling has been incorporated to calculate the electrical performances of β-Ga2O3 (001) vertical SBDs. This model parameters were revised through a series of reported experimental data, which presents that the electron mobility anisotropic ratio of 7 between two orthogonal directions ([100] and the normal of (001) orientation), resulting in much reduced mobility perpendicular to the device surface. Additionally, the forward characteristics and reverse recovery properties of β-Ga2O3 SBDs over range of 300–500 K were investigated by means of calibrated anisotropic mobility model. As a result, the on-resistance is much increased mainly leading to the degradation of the static forward mode, while a lower reverse current peak (Irr) for switching characteristics. The modified mobility modeling considering anisotropy provides a precise curve-fitting to the measurements of on-state characteristics of β-Ga2O3 SBDs, enabling a more accurate prediction of device performance.