Spontaneous nanostructural island formation and layer-to-island mass transport in Ge layers on Si 111/ surfaces

We have deposited Ge on Br-passivated Si 111.surfaces under high vacuum HV.conditions at room temperature RT.. Ge has grown in a layer-plus-island growth mode. Atomic force microscopy AFM.measurements on the as-deposited samples show the formation of nanostructural islands. On a 5008C-annealed sample, the size and the density of islands increase. High resolution X-ray diffraction HRXRD.and ion channeling experiments show the lack of epitaxial growth. However, Raman spectroscopy measurements show the polycrystallinity of the Ge layer. X-ray reflectivity XRR.and Raman spectroscopy results show that the GerSi interface is sharp for the as-deposited layer and there is no significant intermixing even in the annealed samples. AFM, XRR and Raman spectroscopy results, taken together, indicate mass transport from the Ge layer to Ge islands. The temperature dependence of this mass transfer provides effective activation energy of 0.45"0.04 eV. q2000 Elsevier Science B.V. All rights reserved