Normally-off AlGaN/GaN-based MOS-HEMT with self-terminating TMAH wet recess etching

•Normally-off was achieved by self-terminating TMAH wet etching.•Hysteresis of threshold voltage was smaller than 50 mV.•Self-terminating recess showed good distribution of threshold voltage for 30 devices. Normally-off AlGaN/GaN-based MOS-HEMT has been fabricated by utilizing damage-free self-terminating tetramethyl ammonium hydroxide (TMAH) recess etching. The device exhibited a threshold voltage of +2.0 V with good uniformity, extremely small hysteresis of ∼20 mV, and maximum drain current of 210 mA/mm. The device also exhibited excellent off-state performances, such as breakdown voltage of ∼800 V with off-state leakage current as low as ∼10−12 A and high on/off current ratio (Ion/Ioff) of 1010. These excellent device performances are believed to be due to the high quality recessed surface, provided by the simple self-terminating TMAH etching.