Asymmetry in surface morphology and dislocation nucleation of In1−x Ga x As/001) InP single heteroepitaxial layers

Abstract

Abstract The surface morphology and the dislocation structure of MOCVD grown In1−x Ga x As epitaxial layers (x ≈ 0.5…0.73, tensile stress conditions) on (001) surfaces of InP substrates have been studied for layers of various thicknesses (t = 0.6…4.5 μm). Surface corrugations due to dislocation slip parallel [1[unk]0] and due to fracture parallel [110] have been studied quantitatively and correlated to the internal dislocation structure. Tensile strain of the layer is released by nucleation of partial dislocations at the free surface and not at the layer/substrate interface. The model of Marée et al. is in good agreement with the observations. From simple crystallographic arguments it is concluded that partial dislocations with excess In-Ga atoms in the core can be generated more easily than dislocations with excess of As atoms.