The structural and chemical properties of self-assembled InAs islands, grown onto GaAs(001), were studied by using X-ray scattering. Two measurements, performed under grazing incidence conditions, were correlated so as to obtain the 3-dimensional strain and chemical status of InGaAs coherent islands. Grazing-incidence diffraction was used to reveal the in-plane strain-size interplay. By mapping the reciprocal space near to the GaAs(022) reflection and correlating the in-plane and out-of-plane strain information, it was possible to quantify the tetragonal distortion of the unit cells at any position within the islands. The simple theory of alloy elasticity permitted an analysis of the elastic deformation of the unit cells. Any variation in the expected tetragonal distortion of the unit cell was attributed to the presence of Ga atoms within the islands. By using this method, the Ga content in the islands was shown to vary linearly from 25% (island bottom) to 8% (island top).

Determination of Ga Interdiffusion in InAs:GaAs(001) Islands by X-ray Reciprocal Space Mapping. A.Malachias, W.N.Rodrigues, M.V.B.Moreira, S.Kycia, R.Magalhães-Paniago: Journal of Physics D, 2003, 36[10A], A249-52