This work focuses on a comparison of two GaN high-electron mobility transistors (HEMTs) epilayer structures, a single- (SH) and a double-heterostructure (DH). DC and pulsed tests reveal lower ID and Ileak in DH devices. Kink effect is also reported; none shows relevant current collapse. DH HEMTs show a much higher breakdown voltage (VBR) and slope. Off-state step-stresses confirm good reliability for these devices thanks to improved back-barrier confinement; SH suffers from punch-through resulting in premature breakdown
