Trap analysis on GaN HEMT after DC accelerated tests

Several groups have demonstrated nitride-based High Electron Mobility Transistors (HEMTs) with excellent rf output power and with a constant increase in performances. However, despite the large efforts spent in the last few years, and the progress in MTTF (Mean Time To Failure) values, reliability of GaN HEMTs still has to be fully demonstrated, due to the continuous evolution of adopted processes and technologies, and to the lack of information concerning failure modes and mechanisms. The role of temperature in promoting GaN HEMT failure is controversial, and the degradation accelerating factors are largely unknown. This paper analyses the effects of DC accelerated tests at different temperatures in static and dynamic characteristics. From gate-lag tests, the activation energy of the trap responsible to the degradation of dynamic behaviour has been extracted