Effect of Ewald sphere curvature on the GISAXS analysis of capped Germanium nanodot samples in the soft X-ray region

Abstract

Use of soft X-rays (SX) for assessing three dimensional structures in thin films by grazing-incidence small-angle X-ray scattering (GI-SAXS) has been discussed with an example of Ge nanodot structures grown on (001) Si substrates and capped with Si. GISAXS patterns obtained by the measurements were compared with model calculations, and several characteristic differences between GISAXS in the SX and that in hard X-rays have been discussed. It was concluded that although the curvature of the Ewald sphere slightly affects the two-dimensional GISAXS profiles, a two dimensional detector can be still used at the photon energy of about 2 keV. On the other hand, such effect may become dominant when the size of the nanostructure becomes smaller and the photon energy decreases.