THE ENERGY OF SYSTEMS OF MISFIT DISLOCATIONS IN EPITAXIAL STRAINED LAYERS

Theories for calculating the energy and equilibrium configuration of epitaxial strained layers containing interfacial dislocations are reviewed and compared. The two most often used early theories are equivalent, but deficient in that they do not represent the true nature of the stress distribution in the system; in particular they ignore interactions between dislocations. A recent exact theory for infinite two-dimensional arrays of regularly spaced dislocations has revealed subtle behaviour close to the critical thickness and that the earlier theories significantly underestimate the dislocation density at the true equilibrium configuration. A new method of calculating the energy has been developed which is capable of addressing finite systems of irregularly spaced dislocations. The effect of a finite number of dislocations is to increase the equilibrium dislocation density, whereas non-uniformity decreases the dislocation density.