Grazing incidence structural characterization of InAs quantum dots on GaAs(0 0 1)

Abstract

Grazing incidence small angle X-ray scattering (GISAXS) and X-ray diffraction (GIXRD) experiments have been performed on self-assembled InAs quantum dots (QDs) grown by molecular beam epitaxy (MBE). In GISAXS we find pronounced diffuse scattering peaks with high diffraction orders along [110], [1−10] and [100] orientation. From the intensity observation of QD facet truncation rods, we determine an octagonal-based dot shape with {111} and {101} facet families. By analyzing structural parameters such as mean dot–dot distance and correlation length, we propose an anisotropic ordering of QD distribution. From GIXRD of the (202) Bragg peak, we reveal different strain components with elastic deformation in lateral and vertical directions of samples when the InAs QDs are formed. Moreover, we also resolve additional diffraction intensity from unstrained InxGa1−xAs alloy.