Reverse-blocking AlGaN/GaN normally-off MIS-HEMT with double-recessed gated Schottky drain

Abstract

A reverse blocking AlGaN/GaN normally-Off MIS-HEMT featuring double-recessed gated Schottky drain was demonstrated on a double-channel HEMT platform. Two recess steps with robust recess depth tolerance are performed to form the MIS-gated Schottky drain. The shallow recess stops at the upper GaN channel layer where a MIS-gated section (i.e. MIS field plate) is formed to suppress the reverse leakage current. The deep recess cuts through the lower 2DEG channel where a metal-2DEG Schottky contact with low turn-on voltage is formed along the sidewall. Since the lower channel is separated from the surface of the shallow recess, the MIS-gated section in the drain maintains a high mobility channel to yield a sheet resistance of 806 Ω/Square. The device exhibits a threshold voltage of +0.6 V at a drain leakage current of 10 μΑ/mm and +1.9 V from linear extrapolation, and a low differential ON-resistance of ∼11 Ω/mm. Owing to the presence of the metal-2DEG Schottky contact and the leakage-suppression MIS field plate in the drain, a low forward turn-on voltage of 0.5 V and a low reverse leakage current of 20 nA/mm (at −100 V) are achieved simultaneously. The device also exhibits a high forward and reverse breakdown voltage of 700 V and −600 V.