Structural Investigations on Self-Organized Si/SiGe Islands by Grazing Incidence Small Angle X-Ray Scattering

Abstract

We present a novel technique, based on grazing incidence small angle X-ray scattering (GISAXS), with which information on the shape and the lateral correlation of buried islands can be obtained. The GISAXS measurements were performed on Ge-rich islands grown by molecular beam epitaxy on (001) vicinal substrates with a miscut 2° along the [100] direction. By varying the angle of incidence, GISAXS data sets were obtained for different information depths. These data were analysed quantitatively using a model based on the distorted wave Born approximation. In order to demonstrate the capabilities offered by this technique a 20 period Si/SiGe island multilayer sample was investigated before and after an annealing step at about 750 °C for 80 min. The GISAXS data show that the islands change their shape after annealing. For the top island layer a comparison of the GISAXS data with atomic force microscopy topographs was made.