Normally-off AlGaN/GaN high electron mobility transistors on Si substrate with selective barrier regrowth in ohmic regions

Abstract In this paper, we report the fabrication of a normally-off AlGaN/GaN high electron mobility transistor (HEMT) using an ultra-thin AlGaN barrier layer structure on Si (111) substrate. Additional AlGaN layers were selectively regrown only on the ohmic contact areas. The fabricated device exhibits a positive threshold voltage of 0.3 V, a maximum drain output current of 753 mA mm −1 at gate voltage of +4 V, and low gate leakage of 1.2 × 10 −7 A mm −1 . The selective area growth method shows a promising way to achieve normally-off GaN based HEMTs with very good performance.