A Generalized Approach to Determine the Switching Reliability of GaN HEMTs on-Wafer Level

In this work, a detailed analysis of the turn-on behavior of E-mode p-GaN HEMT is reported, with a focus on the impact of hard switching conditions. The study is carried out by means of a novel custom system, developed with the purpose of investigating-on wafer level-the impact of hard switching stress in terms of dynamic on-resistance (RDSON), turn-on switching locus, and power dissipation. The novelty of our approach comes from the high speed of the turn-on commutations (in the range of 10 V/ns), which enables a realistic assessment of the power device performances before the packaging-level, thus shortening the technological development loop. The DUT is tested at high frequency (100 kHz) and different stress conditions: (i) by increasing the voltage at the drain side (VDD), and (ii) by increasing the load capacitance to study the effect of the slew-rate on the dynamic RDSON of GaN devices. The results indicate that even the very short hard switching times reached during fast commutation (few ns) can lead to the increase in dynamic RDSON of power GaN devices, thus providing important information on the trapping kinetics of hot electrons.