Effects of Substrate Termination on Reverse-bias Stress Reliability of Normally-off Lateral GaN-on-Si MIS-FETs

In this work, reliability characterization under reverse-bias (i.e. off-state with high VDS) stress was conducted on the E-mode GaN MIS-FETs with different substrate terminations. The MIS-FETs with a floating substrate exhibit stronger VTH instability than those with a grounded substrate. A non-monotonic dependence of VTH shifts on the positive substrate bias was also observed. The underlying mechanisms are proposed to be the impacts of positive substrate bias on holes drift during long-term reverse-bias stress.