X-ray study of strain, composition, elastic energy and atomic ordering in Ge islands on Si(001)

Abstract

X-ray diffraction techniques were employed here to study several structural and chemical properties of Ge:Si(001) islands. Grazing incidence diffraction was used to map the strain status of Ge pyramids and domes. By tuning the x-ray energy near the Ge K edge to perform anomalous diffraction measurements it was possible to determine the chemical composition of both types of islands. The elastic energy was directly evaluated and found to be one of the driving forces of morphological evolution in this system. These results were extended by a new analysis method to a complete threedimensional chemical and structural mapping of Ge domes. Finally, the existence of SiGe ordered alloys was observed inside domes, indicating the important rule played by surface kinetics on Si interdiffusion.