Effect of 2DEG density and Drain/Source Field Plate design on dynamic-RON of 650 V AlGaN/GaN HEMTs

Abstract

The effect of 2DEG density and Drain/Source Field Plate design on dynamic-R_ON of 650 V p-GaN gate AlGaN/GaN HEMTs is investigated in this work. Devices presenting three different AlGaN barrier and p-GaN layer design have been tested by means of Capacitance-Voltage measurements, Static V_DS stress and Pulsed I-V characterization. CV measurements allowed the extraction of 2DEG density, while Static V_DS stress and Pulsed I-V put in evidence the partial recovery of the dynamic-R_ON at high V_DS,stress, potentially explained by a field-driven hole generation mechanism that partially compensates negatively ionized Carbon acceptors in the GaN Buffer. This hypothesis is in line with the trends observed for different 2DEG density and different drain field-plate designs, suggesting that a higher electric field under the drain terminal can significantly reduce R_ON-degradation at high voltages, due to an easier holes generation. Furthermore, Pulsed I-V tests under resistive load switching mode have been addressed, highlighting the impact of the distance between source field plate and drain field plate on the dynamic-R_ON degradation in conventional switch mode operations.