High-Temperature Characteristics in Normally Off AlGaN/GaN Heterostructure Field-Effect Transistors with Recessed-Gate Enhanced-Barrier Structures

High-temperature characteristics in normally off AlGaN/GaN heterostructure field-effect transistors (HFETs) with recessed-gate enhanced-barrier structures were examined up to 300 degrees C, where a high threshold voltage (Vth) of +3.0 V and a high drain current density (I-d) of 610 mA/mm were obtained at room temperature (RT). Interestingly, I-d did not degrade significantly up to 300 degrees C with a small positive shift in Vth from +3.0 to +3.5 V. A model has been proposed that channel electrons should experience a potential step when they pass the nonrecessed/recessed boundary region in recessed-gate structures, which should be related to the observed high-temperature characteristics. (C) 2012 The Japan Society of Applied Physics