Trapping related degradation effects in AlGaN/GaN HEMT

Reliability in GaN based devices still motivates numerous studies because the involved degradation mechanisms are different from that in III-V narrow bandgap devices. Direct investigations on high electron mobility transistors (HEMT) are performed with low frequency noise (LFN) measurements and pulsed electrical characterization. Undoped AlGaN/GaN devices grown on silicon substrate are stressed at a junction temperature of 175°C. Gate-lag and drain-lag measurements method have been performed versus different quiescent bias points and under different pulse conditions. This method allows the discrimination of each lag phenomenon as well as the thermal contribution. Thus it is possible to track and model the trapping mechanisms versus bias conditions. This electrical modelling is completed with LFN measurements, which is largely used for reliability investigations.