SCATTERING FROM STRAIN VARIATIONS IN HIGH-MOBILITY SI SIGE HETEROSTRUCTURES/

Computations of scattering rates from strain variations in high-mobili ty n-channel Si/SiGe heterostructures are presented, and the results c ompared with experiment. Two sources of strain variation are considere d-interface roughness and misfit dislocations-both of which form to re lieve strain in the Si channel layer which is under tension. Strain va riations induced by interface roughness are demonstrated to provide a source of scattering which, for highly strained systems of the type co nsidered here, is significantly larger than conventional geometrical r oughness scattering. Misfit dislocations provide a source of localized scattering centers, and an appropriate formalism is developed to desc ribe this case. For both types of scattering, reasonable agreement wit h measured mobilities is found for various values of channel thickness . (C) 1995 American Institute of Physics.