Breakdown enhancement and hot electrons mitigation for p-GaN gate HEMTs by electric field modulation

Abstract

In this article, an enhancement mode (E-mode) p-GaN gate AlGaN/GaN high electron mobility transistor (HEMT) with the novel strain technology (NST) has been proposed. The NST consists of GaN/AlGaN/GaN and AlN/AlGaN/GaN heterojunctions laterally from the gate to drain side. By utilizing the different polarization effect of these two heterojunctions, it laterally forms different density of two-dimensional electron gas (2DEG). Accordingly, it decreases the electric field around the gate and introduces an extra electric field peak far away from the gate edge to improve the breakdown voltage (BV) effectively. The experimental BV of the proposed NST-HEMT is increased by 52 % to 1185 V from 780 V of the conventional HEMT. Meanwhile, the output current of NST-HEMT is almost consistent with the conventional HEMT. Moreover, the NST-HEMT realizes better hot electrons mitigation than conventional HMET, and its Vth and Ron degradations are only 1.38 % and 10.72 % after 8 h stress time.