Semi-On State Hole Generation in GaN HEMTs: Experimental Evidence and TCAD Modeling

Semi-On State Hole Generation in GaN HEMTs: Experimental Evidence and TCAD Modeling ■

Ying-Chun Kuo, Ying-Chun Kuo, Hao Yu, Hao Yu, Nelson de Almeida Braga, Nelson de Almeida Braga, Jingtian Fang, Jingtian Fang, Amratansh Gupta, Amratansh Gupta, Sachin Yadav, Sachin Yadav, Arturo Sibaja-Hernandez, Arturo Sibaja-Hernandez, Ali Reza Alian, Ali Reza Alian, Uthayasankaran Peralagu, Uthayasankaran Peralagu, Nadine Collaert, Nadine Collaert, Bertrand Parvais, Bertrand Parvais

Abstract ■

We explore the physical mechanisms responsible for hole generation in GaN HEMTs in the semi-on state by experimentally investigating dependence of gate-collected hole current on VDS, VGS and temperature. Three key observations contradict conventional impact ionization: the hole current (1) saturates at high electric fields, (2) exhibits a positive temperature dependence, and (3) has a low trigger voltage of VDS = 27V at 5 K, which is significantly below the GaN bandgap energy. We therefore propose trap-assisted hole generation as the underlying mechanism and implement a corresponding behavioral model in TCAD. TCAD simulations accurately reproduce the observed dependencies of hole generation on VDS, GDS and temperature.