600 V high-performance AlGaN/GaN HEMTs with AlN/SiNx passivation

The current collapse suppression capability after high OFF-state drain bias stress of a newly developed passivation technique using an AlN/SiN _xstack structure without multiple field plates in high-voltage AlGaN/GaN HEMTs is demonstrated in this work. The increase of dynamic R _ON is suppressed to only 58% of the static R_ON during OFF-ON switching after a high drain bias stress of 650 V. The AlN/SiN _x-passivated HEMTs deliver a high ON/OFF current ratio of more than eight orders of magnitude. The maximum drain current reaches 900 mA/mm, while the drain leakage current remains below 0.7 μA/mm at V_DS up to 600 V with V_GS = -5 V. Owing to the low OFF-state leakage, a steep subthreshold slope (SS) of 63 mV/dec was simultaneously achieved. The breakdown voltage of the AlN/SiNx-passivated HEMTs with a specific ON-resistance of 1.3 mΩcm² was measured to be 632 V at a drain leakage current of 1 μA/mm, resulting in a high figure of merit (FOM = BV²/R _{on, sp}) of 310 MW·cm², which is highly desirable for high voltage power switching applications.