GaN junctionless trigate field-effect transistor with deep-submicron gate length: Characterization and modeling in RF regime

Radio-frequency (RF) performances of a gallium nitride (GaN)-based junctionless (JL) trigate field-effect transistor (TGFET), or fin-shaped FET (FinFET), are demonstrated along with RF modeling for the first time. The fabricated GaN JL TGFET had a gate length of 350 nm and had no AlGaN/GaN heterojunction on which conventional high-mobility electron transistors (HEMTs) had been based to have a fully junctionless channel. The device with five fin channels exhibits a maximum drain current of 403 mA/mm and maximum transconductance of 123.6 mS/mm. The maximum cutoff frequency (f_T) and maximum oscillation frequency (f_max) are 2.45 and 9.75 GHz, respectively. In order to confirm its potential for high-frequency applications, small-signal modeling has been carried out up to a frequency above the maximum f_T.