Stress Reliability Study of GaN HEMT Devices

Gallium Nitride (GaN) high electron mobility transistors (HEMTs) are invented as promising replace to existing Si and GaAs based devices in the RF/Micro-Wave power amplifiers and high-power switching fields. Along with the fast development of device technology and circuit design methodology, the reliability issue of GaN HEMTs is becoming great challenge for circuit designers and simulator. In this report, the stress reliability of E-mode HEMT at the conductance state is investigated. The characteristic forward gate voltage is verified, once above which the switch voltage shows a little while always negative direction drift. This character seems to be nonrecoverable even rest time over one days while above 400°C high ratio annealing. On the other hand, the enhanced HEMTs show more good reliability once the work voltage less the characteristic gate voltage. The enhanced stability of turn on voltage provides evidence to support the fact the characteristic voltage drift is not external high E-field independent physical phenomenon. These results provide better understanding for GaN HEMT circuit design and device process technology development.