Development of coupled thermo-electrical-mechanical models for studying degradation of AlGaN/GaN HFETs

We present a coupled thermo-electricalmechanical finite element based model to investigate material behaviors of wide bandgap (WBG) devices in operating conditions. The mechanisms of degradation and ultimately failure in wide bandgap devices are very complex. Under operating conditions, the devices are usually subject to high electric fields, high stress/strain fields, high current densities, high temperatures and high thermal gradients. The application of electronic devices is limited by lack of a detailed understanding of involved mechanisms. There is a long overdue of development of a comprehensive model which fully couples thermal, electrical and mechanical effects. The proposed model is capable of computing stress, temperature, and electric fields based on an innovative finite element approach for the solution of non-linear coupled thermo-electrical-mechanical problems. The developed model will address major issues of performance and lifetime of wide bandgap electronic devices.