Comparison of sub-micron Si:SiGe heterojunction nFETs to Si nMOSFET in present-day technologies

The measured performance of sub-micron Si:SiGe Schottky gated HFETs is compared to Si nMOSFETs. To allow an up-to-date comparison between Si and strained-Si FETs, the different device types have been studied in their respective technologies. RF performance as given by the cut-off and maximum oscillation frequency is given as a function of input power. The evaluation highlights the current immaturity of the Si:SiGe technologies, where an average HFET shows a maximum transconductance of ∼300 mS/mm and cut-off frequency ∼60 GHz, while the new generation Si nMOS is reaching 1300 mS/mm and 120 GHz respectively. The comparison shows that the strength of the HFETs lies in low power operation (<200 μW).