Special Topic Issue on the Theme of
Nanostructured Systems
Distribution and shape of self-assembled InAs quantum
dots grown on GaAs (001)
K. Zhang*, J. Falta, Th. Schmidt, Ch. Heyn, G. Materlik,
and W. Hansen
*Institut für Angewandte Physik,
Universität Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
Abstract: Grazing incidence small angle X-ray scattering
(GISAXS) and atomic force microscopy (AFM) experiments are employed
to study self-assembled InAs quantum dots (QDs) grown by molecular beam
epitaxy (MBE) on GaAs (001). The GISAXS spectra show pronounced non-specular
diffuse scattering satellite peaks with high diffraction orders up to
±3 along [110], [1-10], and [100] sample azimuthal orientations
with respect to the incoming beam, indicating a lateral ordering of
the InAs QDs. The correlation lengths of the lateral dot distribution
are found to be identical along [110] and [1-10] but smaller along [100]
direction. The ratio of the mean dot-dot distances along [100] and [1-10]
azimuths is determined to be 1.13, indicating the anisotropic ordering
of QD distribution. Broad diffraction peaks are observed at larger scattering
angles and associated to dot facet crystal truncation rods (CTR). We
determine {111}-like facets along [110] and [1-10] sample azimuths,
and {101}-like facets along [100] azimuth.