High-voltage stress time-dependent dispersion effects in AlGaN/GaN HEMTs

In this work we investigate the dispersion effects of GaN based HEMTs as a function of the off-state stress voltage and the stress time. We characterize the reduction of the drain current in on-state after off-state stress time from 2 μs up to 10 s. In addition, we compare different source- and gate-terminated field plate configurations. High-voltage (HV) pulsed stress tests with several stress rates are carried out to measure the increase of dynamic on-resistance over time. A new analytic model is developed to estimate the relevant trapping and detrapping time constants of the devices. By HV pulsed stress tests at different temperatures it is possible to estimate the activation energies for both processes.