Microstructural aspects of island nucleation process in elastically relaxed LPOMVPE grown In_0.2Ga_0.8As/GaAs multilayer

A strained superlattice composed of five bilayers of In_0.2Ga_0.8As/GaAs grown on a (001) GaAs substrate was studied via comparison of the measured high-resolution reciprocal space maps near to the various substrate Bragg peaks with the theoretically modelled intensity distributions. Fourier synthesis was used to describe the strain field and the morphology of the nucleated islands. Modelling, which explains the presence of the side intensity maxima, shows that the lateral compositional variation produces domains with enriched In concentration surrounded by In depleted regions. The distribution of the strain field in both substrate and the multilayer suggests that the compositional modulation promotes nucleation of the islands with a skew vertical correlation on the subsequent interfaces.