Insulated p-GaN Gate Active-Passivation HEMT Maintaining Effective Hole Injection for Low Dynamic ON-Resistance

The p-GaN gate active-passivation HEMT (AP-HEMT) suppresses dynamic R-ON degradation owing to the screening effect by mobile holes against the surface traps and the hole emission effect that pumps out the buffer traps. Therefore, the function of AP-HEMT heavily relies on the hole injection into the active passivation from the gate terminal, and thus the gate/p-GaN contact needs to be an ohmic junction. Unlike the more popular Schottky-type p-GaN gate HEMT where a larger gate driving margin is possible, the Ohmic-type p-GaN gate HEMT suffers from a tight gate driving margin (similar to 3.5 V) which makes it difficult to use from the circuit designers' perspective. In this work, we develop an E-mode metal/insulator/p-GaN gate active-passivation HEMT (MIP-AP-HEMT) which includes a main transistor and a D-mode HEMT network. The main transistor features an MIP gate structure which enlarges the gate driving margin. The D-mode HEMT network features two integrated small D-mode HEMTs to provide a well-controlled gate current that supplies mobile holes for active passivation, and to provide a low-resistance path between p-GaN and gate metal to maintain a stable threshold voltage. The fabricated MIP-AP-HEMT demonstrates a large gate driving margin of 19.4 V, while maintains a highly stable threshold voltage and an effective suppression of dynamic R-ON degradation.