Formation of combined partially recessed and multiple fluorinated-dielectric layers gate structures for high threshold voltage GaN-based HEMT power devices

•The novel HEMT gate structure is theoretically simulated and experimentally verified.•Multiple fluorinated gate dielectric layers are deposited on recessed barrier.•High Vth around 5 V and low gate leakage current at pA/mm level are achieved.•The proposed gate structure is promising in future power switching applications.

The formation of partial AlGaN trench recess filled with multiple fluorinated gate dielectric layers as metal–insulator–semiconductor (MIS) gate structure for GaN-based HEMT power devices is designed, fabricated and experimentally verified. The approach realizes the device normally-off operational mode and at the same time is able to preserve the good mobility in the 2DEG channel for a maximum on-state current. Experimental measurements on the fabricated MIS–HEMT devices indicate a high gate threshold voltage (Vth) at around 5 V and a very low gate leakage current at pA/mm level. This proposed gate structure provides very promising properties for GaN-based power semiconductor devices in future power electronics switching applications.