Microstructures and critical thicknesses of InxGa1-xAs/GaAs strained-layer structures

The development of structural defects in In x Ga 1-x As/GaAs strained-layer structures, grown by molecular beam epitaxy, was investigated by transmission electron microscopy. Three different critical layer thicknesses, corresponding to the formation of three different types of defects, were observed with increasing thicknesses of the strained layers. These defects were: rough interfacial topographies resulting from an onset of three-dimensional growth for the In x Ga 1-x layers; misfit dislocations of the 60 degrees mixed type; and dislocation complexes consisting of planar defects on (111) planes.