Chemical mapping of individual semiconductor nanostructures.

We demonstrate experimentally the power of a novel analytical tool for X-ray spectromicroscopy. This provides a minimally intrusive elemental mapping of surfaces at the nanoscale and holds the promise of remarkable versatility. We have applied our procedure to the characterization of Ge(Si) islands on Si(111) substrates, with the aim of investigating the surface stoichiometry gradients and gaining insight into the intermixing dynamics. By identifying Si-richer edges with respect to the centers, we are able to associate alloying in these islands to surface transport processes.