GaN-Based High Electron Mobility Transistor with Trench-Composite Gate and Asymmetric InAlN/AlGaN Barriers
摘要
Compared to traditional AlGaN/GaN high electron mobility transistors (HEMTs), the strong polarization effect at the In0.17Al0.83N/GaN heterojunction interface significantly enhances the two-dimensional electron gas (2DEG) density, providing greater current carrying potential for power device applications. The present paper puts forth a novel HEMT device structure (CGAB-HEMT), whose innovation lies in the integration of a p-type GaN cap layer on the etched In0.17Al0.83N/GaN and AlGaN asymmetric barrier layers. Through systematic optimization of the key structural parameters of the p-GaN cap layer using a TCAD device simulation platform, significant improvements in the device’s DC characteristics have been successfully achieved. Initial simulation data show that the optimized device exhibits improved maximum saturation current (Isat) and peak transconductance (gm), but the negative drift in threshold voltage (Vth). To address this issue, this study introduces a novel p-type GaN buried layer within the GaN buffer layer directly below the gate region. This layer restricts carriers and enhances channel electron confinement, thereby increasing Vth. To overcome the output current limitation of conventional devices, this study proposes introducing n-type doped GaN buried layers in the GaN channel regions on both sides of the gate. This design enhances the device’s Isat. Compared to the traditional AlGaN/GaN HEMT, Isat increases by approximately 10.5%, reaching 1614 mA/mm, with Vth at 2.8 V. These results indicate that the trench gate p-GaN structure, combined with asymmetric barrier layers and p-type GaN buried layers, constitutes a viable approach for the development of power electronic devices characterized by enhanced saturation current and elevated Vth.