Reliability of AlGaN/GaN HEMT: Impact of acceleration condition on dominant degradation mechanism

Reliability issue for AlGaN/GaN HEMT is in focus of today's research, especially for high voltage operation. RF overload tests at various channel temperatures and drain bias were performed using on-probes reliability testing allowing quick feedback to technology. Two degradation mechanisms: inverse piezoelectric effect and electron trapping were recognized. Unambiguous identification of degradation mechanism by gate current evolution was proposed. Mapping of dominant degradation mechanism as a function of channel temperature and drain bias was performed for given technology. Both electron trapping and inverse piezoelectric effect depend on electric field and on channel temperature, which are controlled by operational biases and base plate temperature consequently.