A novel test methodology for R ON and V TH monitoring in GaN HEMTs during switch-mode operation

One of the critical issues limiting the performances and reliability of GaN power devices is the degradation of their on-resistance (Ron) when they are operated at high drain-source voltages. Being able to monitor RON variation during device operation thus becomes a necessary task in order to investigate the physical mechanisms leading to the observed drifts. Standard measurement equipment does not allow to perform easily this task, specifically when Ron variation should be monitored when the device operates in switch-mode. Moreover, to better understand the physical mechanisms involved it is very important to monitor other device parameters such as its threshold-voltage VTH which is typically not monitored during device switch-mode operation. Therefore, in this work is presented a novel testing methodology which allows the simultaneous monitoring of device Ron and Vth during switchmode operation with the ability to capture the variation of said parameters starting from the very first switching cycles.