Demonstration of High-Performance PMOSFETs Using $ \hbox{Si}$–$\hbox{Si}_{x}\hbox{Ge}_{1 - x}$ –$\hbox{Si}$ Quantum Wells With High- $\kappa$/Metal-Gate Stacks

Through a systematic approach, PMOSFETs with strained quantum wells (QWs) in the Si-Ge system exhibiting high performance and low off-state leakage currents comparable to optimized gate stacks on Si are demonstrated. The encouraging results are due to selectively depositing Si-Si
_x
Ge
_1-x
-Si heterostructure QWs, where it appears that the critical thickness requirements for these thin films based on the lattice constant mismatch are relaxed. Furthermore, the use of optimal advanced high-k dielectric and metal-gate electrode helped realize the good device characteristics.