Impact of Substrate connection on Dynamic-RON drift of 650V normally-off Monolithic Bidirectional AlGaN/GaN HEMT

In this letter, we investigate the dynamic-RON drift of monolithic Bidirectional AIGaN/GaN HEMTs. To this end, a novel measurement setup is proposed to evaluate the impact of the substrate connection. Particularly, (i) grounded and (ii) floating substrate configurations are compared. The partial recovery of the RON-degradation at high stress voltage is demonstrated, for the first time, on Bidirectional GaN devices with grounded substrate. Conversely, a higher RON-drift is observed with floating substrate configuration, due to the negative back-bias effect experienced during on-state time interval. This extends the knowledge on this topic, providing physical insights into the large degradation observed in previous work by highlighting the detrimental effect of leaving the substrate floating in Bidirectional power switches.