DISLOCATION MULTIPLICATION MECHANISMS IN LOW-MISFIT STRAINED EPITAXIAL LAYERS

The origin of misfit dislocations in significantly relaxed low-misfit strained layers is considered. The characteristics of strain relief due to heterogeneous dislocation nucleation at particles, nucleation of dislocations at the free surface of the layer, and multiplication mechanisms are considered and compared with the observed relaxation behavior of constant composition layers of InxGa1-xAs layers on (001) GaAs. It is proposed that dislocation multiplication is consistent with a wide range of experimental results. The observation that 60°and edge dislocations are often seen lying above, but parallel to, the interface in significantly relaxed layers has prompted a study of the possible multiplication mechanisms that they may form. It is shown that one in four reactions between 60°dislocations may lead to a pair of spiral dislocation sources, and that a single spiral source that operates only once may form at the end of edge dislocations. © 1995 American Institute of Physics.