A 250 GHz millimeter wave amplifier MMIC based on 30 nm metamorphic InGaAs MOSFET technology

A 30 nm gate length InGaAs channel MOSFET MMIC technology is presented. 100 mm semi-insulating GaAs substrates with a metamorphicaly grown InGaAs/InAlAs device heterostructure are used. Al
2
O
3
is deposited as gate dielectric onto the In
08
Ga
02
As channel by atomic layer deposition. The gate layout was optimized for monolithic microwave integrated circuit (MMIC) applications using T-gates and wet chemical recess etching to minimize the parasitic gate capacitances. For a 2 × 20 μm gate width transistor a transit frequency f
T
of 306 GHz and a maximum oscillation frequency f
max
of 381 GHz was extrapolated, respectively. This technology was employed for the fabrication of a 230–275 GHz amplifier MMIC with 4 cascode stages achieving a small signal gain of 12 dB at 250 GHz. To the best of the authors knowledge, this is the first reported InGaAs MOSFET millimeter-wave amplifier MMIC operated in the frequency regime beyond W-band.