Drain Field Plate Effects in p-GaN HEMTs During Surge Voltage Hard Switching

This work comprehensively investigates the effects of drain field plate (FP) configurations on the dynamic breakdown and reliability of 650 V Schottky p-GaN gate HEMTs under single and repetitive surge voltages tresses. Both extended and floating drain FPs lead to improvements in dynamic breakdown voltage and output capacitance (COSS), thereby enhancing the maximum surge energy handling capability. Through a combination of Deep-Level Transient Spectroscopy (DLTS) for localized trap characterization, analysis of post-stress exponential recovery kinetics, Arrhenius-based activation energy analysis, and TCAD electric field simulations, the underlying physical mechanisms are revealed. The extended drain FP is found to intensify the vertical electric field, which aggravates hot electron trapping in deep-level buffer traps. This leads to significant degradation in threshold voltage (Vth) stability and on-state conduction characteristics during 650 V surge voltage hard switching. In contrast, the floating drain FP optimizes the drain-side field distribution, effectively mitigating these trapping effects. Consequently, the floating FP configuration demonstrates superior device stability and an enhanced recovery capability after repetitive surge stresses, providing a critical design guideline for robust power switching applications.