Evidence of mobile holes on GaN HFET barrier layer surface - root cause of high power transistoramplifier current collapse

Evidence of mobile, positive charges (holes) on the top surface of GaN HFET is found by conducting C-V measurement of a MIS HEMT diode. Significantly improved understanding of the effects of built-in electric polarization and doping on III-nitride heterojuction device structure electrical properties has been made. The result also confirms that removal of surface mobile holes is the root cause for high power GaN HEFT current collapse.