Study On Hole Mobility And Crystal Orientations Of Strained Si

With the advantage of high-mobility and compatible processing technology with traditional silicon, strained Si has become current research area and development priority of concern at home and abroad, and has great application prospects in high-speed / high-performance devices and circuits. The study of strained Si mobility has very important theoretical value and significant guidance on new strained silicon devices and circuit design. At present, the study on crystal orientation of strained silicon material has been reported rarely, while the crystal orientation is an important factor affecting mobility.The main work is focused on models of hole scattering mechanisms and hole mobility which is related to the crystal orientations and stress of strained Si. The formation mechanism, energy band, hole density-of-state effective mass of strained Si have been analyzed first., then hole mobility enhancement mechanism is analyzed. From quantum mechanisms theory, based on the model of hole density-of-state effective mass, a series of scattering rate models of mechanisms are built, including ionized impurity scattering, acoustic phonon scattering, apolar optical phonon scattering. Based on anisotropy of hole conductance effective mass, the quantification relationship among hole mobility, crystal orientations and stress is got. The results show that the hole mobility of crystal orientations of strained Si increases obviously with Germanium content increasing, then reach the final saturation, the hole mobility on [001]> [010]>[-101]>[1-10]>[111].The model data quantification in this paper provides a theoretical basis for understanding the physical properties of strained silicon materials and choosing the right crystal orientation and stress intensity in strained Si device design(especially in MOS and CMOS).