Vertically stacked double-channel tri-gate GaN HEMT and SBD with enhanced reverse conduction performance

Abstract

The absence of an intrinsic body diode in gallium nitride (GaN) high-electron-mobility transistors (HEMTs) leads to significant reverse conduction losses and reduced efficiency in power applications. An anti-paralleled GaN Schottky barrier diode (SBD) can be integrated to offer a low reverse turn-on voltage (VON); however, existing integration schemes often suffer from high OFF-state leakage and degraded maximum conduction current. To address this, we propose an integrated tri-gate double-channel device by vertically stacking the top channel as an HEMT and the bottom channel as a freewheeling SBD. A unified tri-gate enhances electrostatic control of both channels and shields the bottom-channel SBD from high electric fields, achieving overall low leakage while maintaining low-voltage-drop freewheeling path. Furthermore, compared to a planar-gate integrated device on the same double-channel platform, the tri-gate integration architecture eliminates parasitic dual turn-on effects and substantially reduces gate charge. Our integrated tri-gate double-channel device achieves a low VON of 0.8 V, ∼30% lower RON, almost twice the maximum drain current in reverse mode than in forward mode, and a high breakdown voltage of 1280 V with leakage below 50 nA/mm at 650 V. The excellent reverse conduction performance makes it highly suitable as the synchronous rectifier in power converters for efficiency improvements.