First Observations on the Trap-Induced Avalanche Instability and Safe Operating Area Concerns in AlGaN/GaN HEMTs

This paper reports the very first systematic study on the physics of avalanche instability and safe operating area (SOA) reliability in AlGaN/GaN high-electron-mobility transistor (HEMT) using submicroseconds pulse characterization, poststress degradation analysis, well-calibrated TCAD simulations, and failure analysis by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Impacts of electrical and thermal effects on SOA boundary and avalanche instability are investigated. Trap-induced cumulative nature of degradation is studied in detail. The root cause for avalanche instability in AlGaN/GaN HEMTs is investigated. Postfailure SEM, energy dispersive X-ray (EDX), and TEM analysis reveal distinct failure modes in the presence and absence of carrier trapping.