Reliability-Limiting Defects in GaN/AlGaN High Electron Mobility Transistors

摘要

GaN-based high electron mobility transistors (HEMTs) have gained popularity in high- frequency, high-power electronics owing to the high breakdown voltage and high mobility of GaN. The reliability of GaN-based devices is still an issue, and a lot of research is under way in order to bring GaN to parity with SiC in high-power application areas. In this work, we study the various reliability issues of GaN/AlGaN HEMTs that were fabricated under different conditions using molecular beam epitaxy (MBE) and metallorganic chemical vapor deposition (MOCVD). We propose physics-based models to predict the reliability of GaN HEMTs, and extrapolate the techniques used to other semiconductor material systems. First, the devices are characterized electrically and then subjected to stress DC and RF electrical stress and exposure to radiation. The defects that cause stress-induced degradation are identified using density functional theory calculations. The generation rate of these defects are helpful in order to predict the failure rate of these devices during their operation.