Is self-heating responsible for the current collapse in GaN HEMTs?

AlGaN/GaN high-electron mobility transistors (HEMTs) are a very promising technology for switching and radio frequency power applications due to the high saturation velocity and large breakdown field of the GaN material. However, the electrical reliability of this material system in both the on and the off-state operation regimes is still a fundamental problem to be solved before the widespread use of this technology can be made.