High-performance normally off AlGaN/GaN high electron mobility transistor with p-type h-BN cap layer

Normally off AlGaN/GaN high electron mobility transistors (HEMTs) with p-type gates are attracting increasing attention due to their high safety and low power loss in the field of power switching. In this work, to solve the Mg difficult activating problem of the conventional p-GaN gate AlGaN/GaN HEMTs, we propose an advanced design for the normally off AlGaN/GaN HEMT with a p-type hexagonal boron nitride (h-BN) gate cap layer to effectively manipulate the channel transport of the device. The simulation results demonstrate that the p-hBN gate cap HEMTs yield superior performance over conventional p-GaN gate HEMTs in terms of output current and breakdown voltage, which can be attributed to the deeper potential well formation at the AlGaN/GaN interface and more accumulation of holes located at the p-hBN/AlGaN interface. Moreover, we investigate the effect of bandgap variation on device performance, taking into account that the exact bandgap of h-BN remains under debate. Herein, valuable insights into h-BN cap-gate E-mode AlGaN/GaN HEMT devices are provided, which could serve as a useful reference for the future development of robust III-nitride material power electronic devices.