THE KINETICS OF STRAIN RELAXATION IN LATTICE-MISMATCHED SEMICONDUCTORLAYERS

A scheme is proposed within which the elements of dislocation propagat ion, interaction, nucleation, and multiplication may be combined to yi eld a model of strain relaxation in lattice-mismatched semiconductor l ayers. interaction between perpendicular dislocations is considered mo re fully than previously, and criteria that determine whether a propag ating threading dislocation will be blocked because of such an interac tion are incorporated into the kinetic model. These criteria are devel oped in detail using the full half-space stresses of a dislocation, an d then an approximation is presented that allows the results yielded b y these criteria to be reproduced almost exactly, using formulae of gr eat simplicity. Theoretical consideration of the nucleation and multip lication processes is found to be more difficult, but elementary treat ments are presented that allow the kinetic model to be tested against experiment with reasonable results. Various problems inherent in the m odelling of strain relaxation are highlighted and discussed.