p-GaN/AlGaN/GaN Enhancement-Mode HEMTs

GaN-based enhancement-mode (E-mode) HEMTs are attracting significant interest for integration of control circuitry and for the added safety of a normally-off device in power switching applications. While previous work reports excellent performance by gate-recessing1 and Fluorine-based plasma treatment2, the Schottky gate turn-on voltage of these devices are at most 2 V. Because high-power switching applications require a threshold voltage of over 1 V for gate signal noise immunity, increasing the gate turn-on voltage is crucial. Utilization of p-GaN barrier below the gate3 depletes the channel and increases the gate turn-on voltage to 3 V, rendering it attractive for high-power applications. In this report we present a p-GaN/AlGaN/GaN E-mode HEMTs with a 3 V gate turn-on and maximum output current exceeding 0.3 A/mm. In addition, pulsed I-V measurement and small-signal performance of these devices are presented and the design space of p-GaN gated E-mode HEMTs are investigated for high-power switching applications.