Substrate Bias Effects up to 400 V of Normally-On GaN-on-AlN/SiC HEMTs in Static and Dynamic Tests

Abstract:
In contrast to conventional GaN-on-Si devices, the insulating SiC substrate effectively prevents current reduction caused by back-gating effects. This work studies lateral 120 mOmega normally-on GaN-on-AlN/SiC HEMTs using AlN instead of compensation-doped GaN as buffer material experimentally. Static characteristics and dynamic switching characteristics of the device at substrate bias stress up to ±400 V are presented. Fast switching with drain-source voltage slew rates up to –80 V/ns during turn-on and +120 V/ns during turn-off are measured in hard-switched operation. The measurement results prove that the GaN-on-AlN/SiC power transistor is a promising candidate for monolithic device integration due to the absence of back-gating effects.