Utilizing low-temperature epitaxial technology, we have developed a novel MOSFET structure consisting of a nano-scale (< 15 nm) strained Silicon (Si) layer grown on a nano-scale SiGe-on-insulator (SiGe-OI) structure. By fabricating n-MOSFETs based on this strained Si/SiGe/SiO2/Si structure, we experimentally studied two effects on the electron mobility in the inversion layer, as compared to MOSFETs based on the conventional silicon on insulator (SOI) structure: the effect of the Ge mole fraction in the SiGe layer, and the effect of the strained Si layer thickness. We observed that the current transport in the strained Si layer was enhanced by a factor of about 1.6 as compared to the unstrained Si in the conventional case. In addition, we found that in the case of a strained Si layer with a thickness of less than 15 nm, as the its thickness was reduced, the electron mobility in the inversion layer decreased.

Keywords: nano-thickness, strained- Si, SiGe, mole fraction, phonon scattering rate, mobility