Strained state of Ge(Si) islands on Si: Finite element calculations and comparison to convergent beam electron-diffraction measurements

Abstract
In this letter we present calculations by three-dimensional finite element method and measurements by convergent beam electron diffraction of the displacement field resulting from misfitting Ge0.85Si0.25 islands on Si(001). A good agreement between the results of both methods indicates that the three-dimensional finite element method is a reliable tool to calculate the strain, and thus the stress field, in such nanostructures. As a result both methods show that the substrate substantially takes part in the elastic relaxation process in such heteroepitaxial systems.