Migration of CrSi2 nanocrystals through nanopipes in the silicon cap

CrSi2 nanocrystals (NC1) were grown by reactive deposition epitaxy of Cr at 550 °C. After deposition the Cr is localized in about 20-30 nm dots on the Si surface. The NCs were covered by silicon cap grown by molecular beam epitaxy at 700 °C. The redistribution of NCs in the silicon cap was investigated by transmission electron microscopy and atomic force microscopy. The NCs are partly localized at the deposition depth, and partly migrate near the surface. A new migration mechanism of the CrSi2 NCs is observed, they are transferred from the bulk toward the surface through nanopipes formed in the silicon cap. The redistribution of CrSi2 NCs strongly depends on Cr deposition rate and on the cap growth temperature.