We report on ultrahigh-speed 80 nm AlInN/GaN high-electron-mobility transistors (HEMTs) grown on (111) high-resistivity silicon substrates. The devices feature a peak measured transconductance g(M) = 415 mS/mm, a maximum current of 1.43 A/mm with a ratio I-ON/I-OFF > 10(6), and current gain and maximum oscillation cutoff frequencies of f(T) = 143 GHz and f(MAX) = 176 GHz, which are the highest cutoff frequencies ever achieved for any GaN HEMTs on silicon substrates. The results demonstrate the outstanding potential of AlInN/GaN HEMTs grown on silicon for low-cost high-performance millimeter-wave electronics. (c) 2010 The Japan Society of Applied Physics