Hole confinement and low-frequency noise in SiGe pFETs on silicon-on-sapphire

We present the dc, ac, and low-frequency noise characteristics of SiGe channel pFETs on silicon-on-sapphire (SOS). The SiGe pFETs show higher mobility, transconductance, and cutoff frequency compared to the Si control devices. A significant reduction in low-frequency (1/f) noise is observed in the SiGe pFETs, and understood to be the result of a lower border trap density sampled at the Fermi-level due to the valence band offset. The linear g/sub m/ of the SiGe pFET's at 85 K shows a secondary peak which is attributed to the turn-on of the surface channel.