Crystal truncation planes revealed by three-dimensional reconstruction of reciprocal space

For studying surface properties of nanocrystals, we present an approach based on a combination of the grazing incidence small angle x-ray scattering (GISAXS) technique and tomographic methods. In this approach, GISAXS data from a micro- or nanometer sized object are collected successively at different azimuthal angular positions, which makes it possible to measure the whole three-dimensional (3D) intensity distribution in reciprocal space. As an example, the full 3D reciprocal space intensity originating from the truncated epitaxially grown (111) facetted SiGe pyramids with a square base on (001) Si substrate was measured. This technique enables us to observe and explain crystal truncation planes which originate from scattering on the edges of the nanocrystals.