Impact of Hot Electrons on the Reliability of AlGaN/GaN High Electron Mobility Transistors

Thanks to the improvements in material quality, gate processing and device design, the robustness of GaN HEMTs against this failure mechanism is improving, leading to submicrometer-gate mmw devices which can withstand critical voltages in excess of VGD=100 V. For those technologies, one may wonder which are the dominant failure mechanisms in on-state conditions, and the related accelerating factors. Hot-electron effects have been frequently quoted as a possible threat for the reliability of GaN HEMTs, due to the simultaneous presence of high electric fields and high channel current density. To date, however, no clear demonstration of the role of hot carriers in determining GaN HEMT degradation has been presented.