具有抑制负向阈值电压漂移和增强抗误开启能力的分裂p-GaN栅HEMT

In the development of the Schottky-type p-GaN gate HEMT, the instable V_ th is always a highlighted problem. Under high V_ DS bias, the potential of the floating p-GaN can be raised by the gate/drain coupled barrier lowering (GDCBL) effect, inducing a noticeable negative V_ th shift. During the fast switching operation, the negative V_ th shift severely aggravates the false turn-on problem. In this work, a split-p-GaN gate HEMT (SPG-HEMT) is demonstrated to effectively suppress the drain-induced negative V_ th shift, enhancing the robustness against false turn-on. At V_ DS =100 V, the conventional p-GaN gate HEMT (Conv-HEMT) suffers a negative V_ th shift of −0.33 V, while the SPG-HEMT exhibits only a minimal V_ th shift of −0.07 V. In the SPG-HEMT, the GDCBL effect takes place only for the p-GaN near the drain side (p _2 ) ; the p-GaN near the source (p _1 ) is isolated from p2 via the gate/p-GaN Schottky junctions, and the influence of drain bias upon p1 is shielded by p2. Then, the impact of negative V_ th shift on false turn-on is evaluated by a half-bridge switching circuit. Due to the obvious negative V_ th shift, the Conv-HEMT is falsely turned on when the V_ GS ringing peak is still much lower than the static threshold voltage ( V_ {th0}) . In contrast, the SPG-HEMT starts to show false turn-on signal only when the V_ GS ringing peak is near V_ {th0} . Overall, the unique device structure of the SPG-HEMT leads to a negligible negative V_ th shift and enhances the robustness against false turn-on.