AN ARRAY OF DISLOCATIONS IN A STRAINED EPITAXIAL LAYER .2. WORK-HARDENING

The sequential generation of dislocations in a strained epitaxial laye r is considered. It is found that an additional work component results from dislocation-dislocation interactions after some dislocations are generated and located in the interface between the epitaxial layer an d the substrate. The interaction energies induced by a single dislocat ion and a dislocation array are derived. It is found that, in general, when the distance between a fresh dislocation and the nearest pre-exi sting dislocation is comparable to the layer thickness, the additional work component achieves the level of the self energy of an isolated d islocation. The additional work increases sharply with decreasing dist ance between the fresh and pre-existing dislocations. If the spacing b etween the dislocations exceeds approximately 20 times the layer thick ness, the additional work becomes insignificant. These results are con sistent with experimental observations.