A REBOUND MECHANISM FOR LOMER DISLOCATION FORMATION IN STRAINED LAYER STRUCTURES

A rebound mechanism is proposed for the formation of Lomer misfit dislocations at interfaces in strained layer structures. The model involves dislocation nucleation at a free surface, glide to the interface, reaction to form the Lomer dislocation and another nucleated dislocation, and glide of the latter to the free surface. For either a strained overgrowth layer or a layer within a multilayer structure, where another interface would replace the free surface, the process is energetically favorable once conditions favor the initial nucleation event. The mechanism is consistent with experimental observations of interface structure, including its thickness dependence, for semiconductor and metal systems.