CRITICAL LAYER THICKNESS FOR MISFIT DISLOCATION STABILITY IN MULTILAYER STRUCTURES

The critical thickness for which the injection of misfit dislocations into a strained layer becomes thermodynamically favorable is treated in a Volterra dislocation model. Both a single interior layer and a multilayer (superlattice) case are considered. The results agree with earlier simple dipole predictions in the limit of large misfit dislocation spacing, but deviate at smaller spacings. With a particular core parameter, the results also agree with atomistic calculations using a parabolic potential for a constrained glide equilibrium case.