Lg = 25 nm InGaAs/InAlAs high-electron mobility transistors with both fT and fmax in excess of 700 GHz

In this paper, we report an L g  = 25 nm InGaAs/InAlAs HEMT on InP substrate that delivers excellent high-frequency characteristics. The device exhibited a value of maximum transconductance ( g m_max ) = 2.8 mS  μ m −1 at V DS  = 0.8 V and on-resistance ( R ON ) = 279 Ω μ m. At I D  = 0.56 mA  μ m −1 and V DS  = 0.5 V, the same device displayed an excellent combination of f T  = 703 GHz and f max  = 820 GHz. To the best of the authors’ knowledge, this is the first demonstration of a transistor with both f T and f max over 700 GHz on any material system.