High-performance SiGe pMODFETs grown by UHV-CVD

Abstract

The fabrication and characterization of 0.1 μm-gate-length SiGe pMODFETs fabricated on UHV-CVD-grown heterostructures with various novel layer structure configurations are reported. We have fabricated Ge/Si0.4Ge0.6 pMODFETs with peak extrinsic transconductance (gmext) values as high as 488 mS/mm at room temperature. These devices also displayed a unity current gain cutoff frequency (fT) of 42 GHz and maximum frequency of oscillation (fmax) of 86 GHz. We have also investigated the performance of Si0.2Ge0.8/Si0.7Ge0.3 pMODFETs on silicon-on-sapphire (SOS) substrates. These devices exhibited dc transconductances as high as gnext = 377 mS/mm, and had values of fT = 49 GHz and fmax = 95 GHz. The first high-frequency noise characterization of SiGe MODFETs has also been performed. Si0.2Ge0.8/Si0.65Ge0.35 pMODFETs grown on high-ρ Si substrates produced minimum noise figures of 1.1 dB (2.9 dB) with an associated gain (Ga) of 18 dB (7.6 dB) at 3 GHz (18 GHz).