Scattering from strain variations in high-mobility Si/SiGe heterostructures

Abstract

Computations of scattering rates from strain variations in high-mobility n-channel Si/SiGe heterostructures are presented, and the results compared with experiment. Two sources of strain variation are considered - interface roughness and misfit dislocations - both of which form to relieve strain in the Si channel layer which is under tension. Strain variations induced by interface roughness are demonstrated to provide a source of scattering which, for highly strained systems of the type considered here, is significantly larger than conventional geometrical roughness scattering. Misfit dislocations provide a source of localized scattering centers, and an appropriate formalism is developed to describe this case. For both types of scattering, reasonable agreement with measured mobilities is found for various values of channel thickness. © 1995 American Institute of Physics.