Dependences of the hole mobility in the strained Si pMOSFET and gated Hall bars formed on SiGe/Si(1 1 0) on the channel direction and the strained Si thickness

Abstract

Strained Si/relaxed SiGe/Si(110) heterostructures are gaining interest as an attractive candidate for a Si-wafer-based material for semiconductor devices with enhanced performances and lower power consumption, since a significant enhancement of the hole mobility has been demonstrated in this system. In this paper, dependences of the hole mobility on the channel direction and the strained Si layer thickness are discussed to reveal detailed transport properties of the (110)-oriented pMOSFETs. A significant anisotropy was found regarding the hole mobility, and the 1¯10 direction was found to be a preferable channel direction regarding the hole mobility. Also, it was found that strained Si layer should be sufficiently thin to achieve a high mobility. The physical mechanisms of the anisotropy and the thickness dependence of the hole mobility are discussed by considering the configuration of defects and the valence band structure.