Enhancement-Mode AlGaN/GaN MIS-HEMTs With High VTH and High IDmax Using Recessed-Structure With Regrown AlGaN Barrier

We report on an Al2O3 /AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistor (MIS-HEMT) with recessed-gate structure and regrown AlGaN barrier. After analyzing the possibility of obtaining high threshold voltage ( ${V}_{\text {th}}$ ) within the framework of Tapajna and Kuzmik model from preliminary experiments using MIS-diode structures, we fabricated a MIS-HEMT with the same materials and structures. The transistor exhibited a high ${V}_{\text {th}}$ value of +2.3 V determined at the drain current criterion of 10 $\mu $ A/mm together with a maximum drain current density ( ${I}_{\text {Dmax}}$ ) of 425 mA/mm. We believe that the adoption of a technology, i. e., AlGaN regrowth on dry-etched GaN surface, previously demonstrated by our group in planar device, is the main key for achieving such desirable performance.