The topographies and defect structures of interfaces in strained-layer structures which had been grown by means of molecular beam epitaxy were investigated by using transmission electron microscopy. A wide range (0.16 to 1.00) of In atomic fractions was investigated. Three different critical layer thicknesses were identified. These corresponded to the formation of 3 types of defect with increasing thickness of the strained layers. These defects were rough interfacial topographies which resulted from the onset of 3-dimensional growth of the InGaAs layers, misfit dislocations of 60 mixed type, or dislocation complexes which consisted of planar defects on {111) planes. By means of a comparison with photoluminescence data, it was found that both types of defect which involved dislocations led to severe degradation of the optical properties of strained-layer structures.

J.Y.Yao, T.G.Andersson, G.L.Dunlop: Materials Science Forum, 1995, 189-190, 285-90