Flicker-Noise Improvement in 100-nm $L_{g}\ \hbox{Si}_{0.50}\hbox{Ge}_{0.50}$ Strained Quantum-Well Transistors Using Ultrathin Si Cap Layer

This letter presents a record low flicker-noise spectral density in biaxial compressively strained p-channel 100-nm $L_{g}\ \hbox{Si}_{0.50}\hbox{Ge}_{0.50}$ quantum-well FETs (QWFETs) with ultrathin Si ($\sim$2 nm) barrier layer and 1-nm EOT hafnium silicate gate dielectric. The normalized power spectral density of $I_{d}$ fluctuations $(S_{Id}/I_{d}^{2})$ in $\hbox{Si}_{0.50}\hbox{Ge}_{0.50}$ QWFETs exhibits significant improvement by ten times over surface channel unstrained Si pMOSFETs at high $V_{g}$ due to strong confinement of holes within the high-mobility QW and strong quantization in the ultrathin Si barrier layer enabled by low-thermal-budget device processing. The noise behavior in strained QW devices is found to evolve from being correlated mobility fluctuation dominated across most of $V_{g}$ range to being Hooge mobility fluctuation dominated at very high $V_{g}$.