Investigation of degradations in p-GaN gate power HEMTs after power cycling test

This study investigates degradations of p-GaN gate power HEMTs after power cycling tests (PCTs) and analyzes their origins, employing both electrical and physical characterization. To achieve this goal, the forward voltage drop of the gate-diode (V F ) and the on-state resistance (R on ) were evaluated as temperature sensitive electrical parameters (TSEPs). PCTs with various junction temperature swings (ΔT j ) were subsequently performed with R on as the TSEP. Experimental results revealed an increase in capacitance-voltage (C V) hysteresis and a negative shift in threshold voltage for all PCT conditions, but distinct behaviors in R on . The detailed electrical and physical analysis suggests two distinct degradations governing the electrical performance of p-GaN gate power HEMT during PCT: (1) device-related predominant degradation associated with time-dependent hole trapping, leading to a decrease in R on and (2) degradation potentially associated with thermomechanical stress under large ΔT j conditions, leading to an increase in R on . These findings demonstrate that R on -based PCT is an effective tool for evaluating the long-term reliability of p-GaN gate power HEMTs and provide critical insights into their failure mechanisms.