Understanding the interfacial layer formation on strained Si_1-xGe_x channels and their correlation to inversion layer hole mobility

We investigate the mechanism of interfacial layer formation on Si1-xGex (0 < x < 0.5) channel and its correlation to hole mobility. It is found that the mobility degradation in low-Ge-content Si1-xGex (x < 0.2) pFETs is attributed to a Ge-rich top surface in the channel directly induced by interfacial layer formation. In addition, the depth profile of a Si-rich top surface in high-Ge-content Si1-xGex channel is presented to understand the surface atomic configuration of Si1-xGex channel as well as mobility enhancement mechanism.