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Electron. Lett. 33 98-99 [5] Matthews J W 1975 J. Vac. Sci. Techno!. 12 126-133 [6] Hsu W C, Shieh H M, Wu C Land Wu T S 1994 IEEE Trans. Electron Devices 41

456-457

Abstract. We applied to a novel multilayer resist system that consists of commercially available positive resist, ZEP520 and P(MMA-MAA), for fabricating T-gate PHEMTs with gate lengths of 70 nm or less, and has manufactured a 70 nm T -gate using electron beam lithography. In this study, devices of 70 J.lm unit gate width and two gate fingers with a drain-source saturation current density of 357.14 mA/mm, extrinsic transconductance of 505.45 mS/mm, fT of as high as 115 GHz and fmax of 175 GHz have been fabricated.