Experimental and Numerical Evaluation of RON Degradation in GaN HEMTs during Pulse-Mode Operation

The on-resistance (RON) degradation in normally-OFF GaN high electron mobility transistors has been evaluated both experimentally and by means of numerical simulations by analyzing its drift during device pulse-mode operation. Experimental data showed that the device RON measured during the on-time interval of the switching period increased with time resulting in a thermally activated process with an activation energy $EA=0.83$ eV. For the first time, numerical simulations have been carried out in order to evaluate the device RON drift during pulse-mode operation and to understand the physical phenomena involved. A good qualitative agreement between experimental and simulated data has been obtained when considering in the simulated device simply a hole trap located at 0.83 eV from the GaN valence-band, an energy level which has been linked in previous works to carbon-doping within the GaN buffer.