RF operation of AlN/Al<sub>0.25</sub>Ga<sub>0.75</sub>N/AlN HEMTs with f <sub> T </sub>/f <sub>max</sub> of 67/166 GHz
Eungkyun Kim, Jashan Singhal, Austin Hickman, Lei Li, Reet Chaudhuri, Yong-Jin Cho, James C. M. Hwang, Debdeep Jena, Huili Grace Xing
Abstract
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 of R 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.