Split-p-GaN Gate HEMT With Suppressed Negative V_th Shift and Enhanced Robustness Against False Turn-On

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 demon strated 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 (p₂); the p-GaN near the source (p₁) is isolated from p₂ via the gate/p-GaN Schot tky 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 Vth shift and enhances the robustness against false turn-on.