The kinetics of strain relaxation in lattice-mismatched semiconductor layers

A scheme is proposed within which the elements of dislocation propagation, interaction, nucleation, and multiplication may be combined to yield a model of strain relaxation in lattice-mismatched semiconductor layers. Interaction between perpendicular dislocations is considered more fully than previously, and criteria that determine whether a propagating threading dislocation will be blocked because of such an interaction are incorporated into the kinetic model. These criteria are developed in detail using the full half-space stresses of a dislocation, and then an approximation is presented that allows the results yielded by these criteria to be reproduced almost exactly, using formulae of great simplicity. Theoretical consideration of the nucleation and multiplication processes is found to be more difficult, but elementary treatments are presented that allow the kinetic model to be tested against experiment with reasonable results. Various problems inherent in the modelling of strain relaxation are highlighted and discussed.