Generation of misfit dislocations in GaAs grown on Si

The misfit dislocation configurations in initial GaAs islands grown on silicon were studied by high-resolution electron microscopy. Misfit dislocations, especially 60° type and stacking faults, were observed to generate from near the edges of the islands. Large steps on the substrate surface were observed to help the nucleation of these dislocations. The presence of threading dislocations in thicker films is attributed to the misfit dislocation segments in initial GaAs islands. A mechanism is proposed to explain the propagation and multiplication of misfit dislocations during the coalescence of islands and their subsequent growth.