Three-dimensional compositional analysis of quantum dots

A simulation program has been set up, which calculates the x-ray profiles o f x-ray line scans taken across features of arbitrary structural and compos itional geometries embedded in a matrix. The simulated scan intensities are compared to experimental scan intensities, obtained in an analytical scann ing transmission electron microscope. The program is applied to calculate x -ray profiles of InAs quantum dots embedded in GaAs and to SiGe quantum dot s embedded in Si in a thin foil in cross-sectional [011] projection. With t he help of simulations of the indium L line scan intensities for the case o f the InAs dots it is demonstrated how sensitively the x-ray profiles depen d on the position of the dot in the thin foil. For the case of the SiGe dot s, a full quantitative composition analysis is carried out by adjusting the model geometry and model composition distribution until the best match wit h the experimental germanium K line scan intensity profile is achieved.