Unique Surface Passivation Stoichiometry Dependence of Dynamic On-Resistance and Its Suppression in p-GaN Gate AlGaN/GaN HEMTs

In this work, we demonstrate the mitigation of dynamic on-resistance in p-GaN gate AlGaN/GaN HEMTs by tuning the stoichiometry of an ex-situ deposited surface passivation layer. Detailed experiments using high-voltage nanosecond pulsed measurements and a fast-switching train of pulses are employed to analyze the dynamic on-resistance behavior of the devices. Frequency-based analysis, electroluminescence analysis, substrate bias dependence, and self-heating profile analysis are used in conjunction with electrical characterization to gain insights into the physical mechanisms related to the dynamic on-resistance dependence on surface passivation stoichiometry. Finally, X-ray photoelectron spectroscopy, cathodoluminescence, and capacitance–voltage analysis reveal that the reduction in surface trap density with nonstoichiometric SiOX passivation leads to improved dynamic on-resistance. These findings establish surface passivation stoichiometry as a critical design parameter for alleviating the problem of dynamic on-resistance in GaN-based power devices.