Normally-Off AlGaN/GaN Metal–Oxide–Semiconductor Heterostructure Field-Effect Transistor with Recessed Gate and p-GaN Back-Barrier

The recessed-gate AlGaN/GaN metal–oxide–semiconductor heterostructure field-effect transistors (MOSHFETs) with a p-GaN back-barrier studied in this work exhibited much lower buffer leakage current than those without the back-barrier. The threshold voltage of the device with the p-GaN back-barrier was controlled by varying the depth of gate recess etching, and a value as high as 2.9 V was obtained with deep gate-recess etching into the channel layer. The device structure has the advantage of both low leakage current and high threshold voltage, which is important for power-switching applications. In contrast, the performance parameters of the device, such as subthreshold slope and field-effect mobility, can be degraded owing to increased plasma damage with increasing recess depth.