Low Current Dispersion and Low Bias-stress Degradation of Unpassivated GaN/AlGaN/GaN/SiC HEMTs

The performance of unpassivated GaN/AlGaN/GaN/SiC HEMTs with intentionally undoped and doped barrier structures are extensively studied. No drain current dispersion between DC and 50 ns pulses on doped devices and less than 10% dispersion on undoped ones is observed. The full (100%) current recovery on undoped sample was measured in 1μs. The drain current extrapolated from 2 GHz large signal measurements corresponds to the measured static drain current confirming negligible current dispersion of our devices. Insignificant (<5 %) degradation in overall device performance parameters (IDs, gm, fT, fmax, Pout) on both undoped and doped structures after 12-hour-long bias stress was obtained. These results documents that suitable device performances can be obtained also on unpassivated GaN-based HEMTs.