Characterization of the crystallographic defect structure in selected-area epitaxial growth of GaInAs on InP by metallo-organic chemical vapour deposition

We describe the chemical and crystallographic structure of selected-area metallo-organic chemical vapour deposition overgrowths of InP and GaInAs on partially masked (100) InP substrates, using energy-dispersive X-ray analysis, transmission electron microscopy and high resolution electron microscopy. The presence of the oxide mask, which specifies the selected areas for epitaxial deposition, has the effect of perturbing the gas flow over the wafer surface, which can induce a modification of the local composition and morphology of the depositing material and result in the incorporation of interfacial misfit stresses. High densities of interfacial misfit dislocations are observed in material in which this perturbation is greatest. The majority of the dislocations in the planar epitaxial regions have a 60° character, but in the highly mismatched and facetted regions of growth adjacent to the mask edges, a variety of novel misfit-relieving dislocation structures are observed and these are identified by high resolution electron microscopy.