20 NM metamorphic HEMT WITH 660 GHZ FT

A metamorphic HEMT MMIC technology with 20 nm gate length is presented, developed for the fabrication of terahertz-wave monolithic integrated circuits (TMICs) with operational frequencies beyond 500 GHz. The MBE grown transistor heterostructure comprises a strained In
_0.8
Ga
_0.2
As channel with high electron mobility and high electron density for proper device scaling. The realized mHEMTs achieve a source resistance R
_S
of 0.1 Ωmm which is required to minimize resistive losses in combination with an extrinsic maximum transconductance g
_{m_max}
of 2500 mS/mm. The output characteristics of the 20 nm devices show no short channel effects and demonstrate sufficient pinch-off behavior for analog applications. For a transistor with 2 × 10 μm gate width a cut-off frequency f
_T
of 660 GHz was extrapolated which is to our knowledge the highest published f
_T
for any HEMT device. The presented 20 nm mHEMT technology was employed for the design of a compact four stage lownoise amplifier (LNA). The total small signal gain of the LNA exceeds 20 dB from 115 - 175 GHz.