The structure of GaAs quantum wires embedded in Ga0.67Al0.33As, and the interfaces between the wires and the matrix, were investigated by means of transmission electron microscopy in the diffraction contrast and high-resolution modes. The quantum wires were re-grown by molecular beam epitaxy onto patterned GaAlAs buffer layers on GaAs substrates. Depending upon the orientation of the quantum wires within the (100) surface of the substrate, various characteristic facets developed during re-growth of the mesa-etched samples. The surface structures of [011]- and [011]-oriented wires were dominated by {111} and {311} facets. Some {111} planar defects, such as stacking faults and twins, were frequently observed in the case of {111} facet growth. Mainly {110} facet formation was found for [001]- and [010]-oriented wires. Planar defects were not detected in this case.

M.Dilger, M.Hohenstein, F.Phillipp, K.Eberl, A.Kurtenbach, P.Grambow, A.Lehmann, D.Heitmann, K.Von Klitzing: Semiconductor Science and Technology, 1994, 9[12], 2258-62