Fast switching performance by 20 A / 730 V AlGaN/GaN MIS-HFET using AlON gate insulator

In this paper, high current and high voltage AlGaN/GaN metal-insulator-semiconductor (MIS) heterojunction field-effect transistors (HFETs) on Si are demonstrated. The devices exhibit a drain current of 20 A as well as a breakdown voltage of 730 V, serving normally-off operations. Stable interfacial characteristics free from the hysteresis in the transfer characteristics are enabled by the introduction of AlON gate insulator. A recessed gate structure formed by epitaxial regrowth of AlGaN over the grooved AlGaN/GaN heterojunction successfully reduces the on-state resistance and eliminates the processing damage on the surface of the grooved structure. Note that an oxygen annealing followed by the deposition of AlON shifts the threshold voltage V
_th
to positive side. The resultant switching performance by the 20 A / 730 V AlGaN/GaN MIS-HFET is very fast with dV/dt of 78 V/ns and 169 V/ns for turn-on and turn-off transitions, respectively, indicating that the proposed MIS-HFETs are very promising for practical power switching applications.