Fully-Vertical GaN-on-SiC Trench MOSFETs

This letter presents the first demonstration of fully-vertical GaN-on-SiC trench MOSFETs enabled by a conductive AlGaN buffer. Good ON-state device performance including a maximum drain current density of 2.43 kA/cm2 and a high threshold voltage of 5 V has been demonstrated. The relatively high specific ON-resistance at low <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\boldsymbol {V}}_{\text {DS}}$ </tex-math></inline-formula> is a result of a knee voltage induced by the yet to be optimized AlGaN/SiC heterojunction. A breakdown voltage of 334 V has been measured. Compared with quasi-vertical GaN-on-silicon trench MOSFETs, less current crowding effect is observed for fully-vertical GaN-on-SiC trench MOSFETs, as well as a better performance at elevated temperatures.