Grazing incidence x-ray scattering: an ideal tool to study the structure of quantum dots

Abstract

We discuss the application of grazing incidence x-ray techniques to characterize nanometer sized islands, which arise in strained layer heteroepitaxy of semiconductor systems (`quantum dots'). Using x-rays from synchrotron sources, grazing incidence small angle scattering (GISAXS) is demonstrated to yield structural information on shape, size and lateral correlation. Results on self-assembled Ge islands on Si(111) substrate are shown as an example. The crystalline properties of coherent quantum dots are obtained from grazing incidence diffraction (GID). From the analysis of reciprocal space maps the interdependence of shape and elastic strain within the quantum dots is determined. We discuss results on coherent InAs quantum structures on GaAs(100).