부산대학교 도서관

We report the state-of-the-art $V$ -band power performance of a scaled 40-nm gate length Al 0.23 Ga 0.77 N/AlN/GaN/Al 0.08 Ga 0.92 N double heterojunction field effect transistor (DHFET). The $200~\mu \text{m}$ ( $4\times 50 ~\mu \text{m}$ ) wide GaN DHFETs pre-matched for $V$ -band (57–64 GHz) have demonstrated an output power of 376 mW (1.88 W/mm) with 48% power-added efficiency (PAE), 57% drain efficiency, and more than 8 dB of associated gain measured at a frequency of 59 GHz. These results represent to the best of our knowledge the best combination of power and PAE reported to date at this frequency for a solid-state device. These results were achieved through optimization of the GaN heterostructure, which incorporates a low aluminum content back-barrier for electron confinement through polarization effects, a vertically scaled Al 0.23 Ga 0.77 N/AlN gate barrier stack for minimization of short-channel effects, and a selective n + GaN ohmic re-growth process by molecular beam epitaxy for reduction of parasitic resistance.