Direct correlation between specific trap formation and electric stress-induced degradation in MBE-grown AlGaN/GaN HEMTs

DC stressing of molecular beam epitaxy (MBE)-grown high electron mobility transistors (HEMTs) is found to degrade device performance primarily due to increased defect/trap formation. Using constant drain-current deep level optical/transient spectroscopy (CI_D-DLOS/DLTS) methods, a specific virtual-gate related electron trap with energy E_C-0.45 eV was observed to increase in concentration following DC stressing. The enhanced formation of this defect correlates quantitatively with a stress-induced knee-walkout (performance-degradation) of the HEMT that manifests itself in the pulsed I-V measurements.