Investigation of Dynamic IOFF Under Switching Operation in Schottky-Type p-GaN Gate HEMTs

In this paper, systematic characterization and the corresponding suppression strategies of dynamic OFF-state leakage current (I-OFF) in Schottky-type p-GaN gate high-electron-mobility transistors (HEMTs) are presented based on fast pulsed I-V measurement and consecutive switching measurement. It is found that the high I-OFF under dynamic pulse mode without hole injection is a result of the reduced voltage blocking capabilities (both lateral and vertical) with weaker trapping effect in the buffer, and the dynamic I-OFF induced by ON-state hole injection is caused by further increased lateral conductivity through the buffer from source to drain. The corresponding behaviors under continuous waveforms with different switching conditions are analyzed to identify effective approaches for the suppression of dynamic I-OFF in practical switching operations. A higher temperature is shown to be beneficial to the reduction of the dynamic I-OFF induced by ON-state hole injection. To completely eliminate the dynamic IOFF caused by ON-state hole injection and minimize the OFF-state power consumption in practical power switching applications, a sufficiently large negative OFF-state gate bias (e.g., V-GS,V- OFF <= -3 V) is recommended in the gate driver turn-off voltage design for the Schottky-type p-GaN gate HEMTs.