An analysis of enhanced performance field-effect transistor (FET) stru
ctures, incorporating the self-aligned gate feature of conventional Si
MOSFETs and the higher carrier-mobility-channel configuration of modu
lation-doped FETs, is presented. A modified charge-control model is de
veloped to account for the incorporation of the MOS gate in a modulati
on-doped FET structure. Electrical characteristics are computed for th
ese devices having strained SiGe layers on Si and/or Ge substrates. Th
eoretical results are computed using the ultra-high hole mobility repo
rted in the literature for the modulation-doped SiGe-Ge-SiGe p-MOSFETs
. It is shown that these devices will extend the use of SiGe based FET
s to over the 80 GHz range for a 0.25 mum gate at 77 K, while maintain
ing the high packing density inherent in Si MOSFETs.