We have investigated the effect of substrate biasing on the subthreshold characteristics and noise levels of Si/Si1-xGex (x = 0, 0.15, 0.3) heterostructure MOSFETs. A detailed analysis of the dependence of threshold voltage, off-state current, and low-frequency noise level on the substrate-source (Vbs) biasing showed that SiGe heterostructure MOSFETs offer a significant speed advantage, an extended subthreshold operation region, a reduced noise level, and reduced bulk potential sensitivity compared to Si bulk devices. These experimental results demonstrate that SiGe heterostructure MOSFETs render a promising extension to the CMOS technologies at the low-power limit of operation, eventually making the microrpower implementation of radio frequency (RF) functions feasible.
- Body effect
- Low power