Design of high breakdown voltage GaN vertical HFETs with p-GaN buried buffer layers for power switching applications

Abstract

To achieve a high breakdown voltage, a GaN vertical heterostructure field effect transistor with p-GaN buried layers (PBL-VHFET) is proposed in this paper. The breakdown voltage of this GaN-based PBL-VHFET could be improved significantly by the optimizing thickness of p-GaN buried layers and doping concentration in PBL. When the GaN buffer layer thickness is 15μm, the thickness, length and p-doping concentration of PBL are 0.3μm, 2.7μm, and 3×1017cm−3, respectively. Simulation results show that the breakdown voltage and on-resistance of the device with two p-GaN buried layers are 3022V and 3.13mΩcm2, respectively. The average breakdown electric field would reach as high as 201.5V/μm. Compared with the typical GaN vertical heterostructure FETs without PBL, both of breakdown voltage and average breakdown electric field of device are increased more than 50%.