Thirty-five-nm T-Gate In0.52Al0.48As/In0.53Ga0.47As Metamorphic HEMTs with an Ultrahigh f(max) of 610 GHz

Abstract

Thirty-five-nanometer T-gate GaAs-based In0.52Al0.48As/In0.53Ga0.47As metaniorphic high electron mobility transistors (mHEMTs) are successfully fabricated using a zigzag-shaped T-gate. We obtain a maximum extrinsic transconductance (g(m)) of 1060 mS/mm and a maximum oscillation frequency (f(max)) of 610 GHz. These superior results are obtained by reducing the T-gate's length to 35 nm without the assistance of a supporting layer and by fabricating a wide-recessed-gate structure. The stand-alone 35-nm T-gate effectively improves the device performance because it doesn't cause additional parasitic capacitances. The wide-recessed-gate structure alleviates impact ionization in the channel, Which suppresses the kink effect in the output characteristic and reduces the output conductance (9(ds))- In addition, the wide-recessed-gate structure reduces the gate-to-drain capacitance (C-gd); consequently realizing a state-of-the-art f(max) The f(max) of 610 GHz, to our knowledge, is the highest value reported to date for GaAs-based HEMTs.