Expressions are presented for the rate of strain relaxation, misfit dislocation nucleation, and propagation in strained Si1minus;xGex/(100)Si heterostructures. Independent measurements of misfit dislocation nucleation and 60deg; typea/2 lang;110rang; dislocation glide velocity in the temperature range 450ndash;1000thinsp;deg;C have led to a model which characterizes the kinetics of strain relaxation for 0x0.25. The generalized force or effective stress tgr;eff, which drives strain relaxation, is defined for an arbitrary strain profile and strainedhyphen;layer geometry. New experimental data for misfit dislocation glide velocity (Vin cmthinsp;sminus;1) have been fitted to a semihyphen;empirical relation found to be appropriate for all Si1minus;xGex/(100)Si heterostructures,V=(4plusmn;2)sdot;1013(tgr;eff/mgr;)2thinsp;expminus;lsqb;(2.25plusmn;0.05)/kTrsqb;. An analogous expression for the nucleation rate of new misfit dislocation segments was determined from experimental data,dN(t)/dt=BN0(tgr;eff/mgr;)2.5thinsp;expminus;lsqb;2.5plusmn;0.2)/kTrsqb;, whereN0is the density of heterogeneous nuclei andBis a material constant sim;1018sminus;1for Si1minus;xGex. These expressions are combined in a kinetic model which is then used to predict the rate of strain relaxation in Si1minus;xGex/Si heterostructures.
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