Technology and performance of E/D-mode InAlN/GaN HEMTs for mixed-signal electronics

Abstract

We describe technology and performance of integrated enhancement/depletion (E/D)-mode n++GaN/InAlN/AlN/GaN HEMTs with a self-aligned gate structure. Identical starting epi-structure was used for both types of devices without additional need for a contacts regrowth. n++GaN cap layer was etched away in the gate trenches of E-mode HEMT while it was left intact for D-mode HEMT. Feasibility of the approach for future fast GaN-based mixed-signal electronic circuits was proved by obtaining alternative HEMT threshold voltage values of 2 V and −5.2 V, invariant maximal output current of ∼0.45 A/mm despite large source-to-drain distances and by demonstrating a functional logic invertor.