Dynamics of carrier transport via AlGaN barrier in AlGaN/GaN MIS-HEMTs

Exchange of carriers between the GaN channel and the dielectric/AlGaN interface in AlGaN/GaN metal insulator semiconductor high electron mobility transistors was recently attributed to a serial process of electron transport through the AlGaN barrier and electron trapping/emission at the interface. In this paper, the time constant related to barrier transport is evaluated from the measurements of time onset of threshold voltage drift in stress-recovery experiments. Temperature and forward gate bias dependent studies reveal an activation energy of 0.65 eV for the electron transport at zero bias being consistent with the estimated potential barrier of 0.75 eV at the dielectric/AlGaN interface. Thermo-ionic emission and defect assisted tunneling to near interface states are considered as transport mechanisms.