Enhancement-Mode GaN MIS-HEMTs With n-GaN/i-AlN/n-GaN Triple Cap Layer and High- $k$ Gate Dielectrics

This letter presents details of high-performance enhancement-mode GaN MIS high-electron-mobility transistor (MIS-HEMT) devices. Devices with an n-GaN/i-AlN/n-GaN triple cap layer, a recessed-gate structure, and high-
k
gate dielectrics show high drain current and complete enhancement-mode operation. The maximum drain current and threshold voltage (
V

_th
) are 800 mA/mm and +3 V, respectively. These results indicate that a recessed AlGaN/GaN MIS-HEMT with the triple cap could be a promising new technology for future device applications.