20.2 GHz‐µm f _T ‐L _G in InAlN/GaN‐on‐Si HEMTs

Herein, InAlN/GaN‐on‐Si high‐electron‐mobility transistors (HEMTs) with an f T –L G product of 20.2 GHz – μm are demonstrated. The device with a gate length of 200 nm and a source – drain spacing of 900 nm exhibits a peak transconductance of 543 mS mm −1 , an I ON /I OFF ratio of ≈10 7 , a maximum on‐current of 2.4 A mm −1 , and an on‐resistance of 1.07 Ω mm. Small‐signal characteristics show a unity current gain cutoff frequency of 101 GHz. Delay time analysis is performed to evaluate various delay components and their contribution to the small‐signal performance of the device. An effective electron velocity of 1.56 × 10 7 cm s −1 is estimated in these devices, which minimizes the intrinsic delay of the transistor. The factors limiting the f T –L G product in deeply scaled devices are discussed using the delay analysis.