Synchrotron radiation plane-wave topography and Rutherford back-scattering techniques were used to investigate lattice tilts between substrates and layers which were caused by the preferential orientation of the Burgers vectors of misfit dislocations in compositionally graded heterostructures. A monotonic change in the lattice tilt along the sample surface, which produced an overall concave curvature of the buffer layer lattice, was found; with an almost complete alignment of the Burgers vector of the misfit dislocations at the sample edges. Topographic observations showed that the buffer layers could follow a nearly continuous curvature, or could be sub-divided into large domains having different average lattice tilts. Current models for the formation of tilts in partially relaxed structures were unable to explain the present observation of a lattice tilt which varied along the sample surface.

Investigation by Synchrotron Radiation X-Ray Topography of Lattice Tilt Formation in Partially Released InGaAs/GaAs Compositionally Graded Layers C.Ferrari, S.Gennari, S.Franchi, L.Lazzarini, M.Natali, F.Romanato, A.V.Drigo, J.Baruchel: Journal of Crystal Growth, 1999, 205[4], 474-80