RF operation of AlN/Al 0.25 Ga 0.75 N/AlN HEMTs with f T /f max of 67/166 GHz
Abstract We report on highly-scaled Al 0.25 Ga 0.75 N channel high electron mobility transistors. Regrown ohmic contacts covering the sidewall of the compressively strained Al 0.25 Ga 0.75 N channel exhibited a low contact resistance ofR c = 0.23 Ω · mm. Scaled devices with a T-shaped gate showed record high speed for any AlGaN-based transistors,f T /f max = 67/166 GHz, while simultaneously achieving high average breakdown field exceeding 2 MV cm −1 . The load-pull measurements performed at 10 GHz revealed a 20% peak power added efficiency with an output power density of 2 W mm −1 , which is mainly limited by the RF dispersion.
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