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Abstract Using scanning tunneling microscopy, the influence of a thin Au layer on the diffusion of Fe adatoms and the subsequent island nucleation on a Si(111) surface is investigated. The adsorbate induces the structure that increases the surface mobility of subsequently deposited Fe atoms, resulting in the formation well-defined nanoclusters. Surprisingly, the domain walls—inherent to the reconstruction—do not influence the surface diffusion, which demonstrates that the passivation is of much more importance for the self-assembly than the surface corrugation. Using the decoupling of the diffusion and nucleationonthe surface and the reactionwiththe surface and conventional nucleation theory, the activation energy for surface diffusionE d = 0.61 eV and the critical cluster sizei = 3 are determined, which reveal the microscopic details of the diffusion and nucleation processes.

Scanning tunneling microscopy was used to investigate the influence of Ag-induced surface reconstructions on the formation of low-dimensional Fe-Si structures. The deposition of 1 Å Fe (i.e., 1.1 monolayer) at 300 °C on the 3 ⊗ 1-Ag, the √ 3 ⊗ √ 3-Ag, and the 7 ⊗ 7 reconstructions of the Si(111) surface results in the self-assembly of small islands. For both Ag-induced reconstructions, these islands are significantly larger compared to those formed on the Si(111)-7 ⊗ 7 surface due to an increased surface diffusion. Moreover, on the √ 3 ⊗ 3 structure, these nanodots are well separated and in between, the initial reconstruction remains unchanged. In the presence of surface steps, these islands preferentially nucleate at the lower step edge, which can be used to grow long continuous nanowires for higher Fe coverage and vicinal surfaces. Furthermore, from the phenomena such as step retraction and island/hole combinations, it is concluded that these nanostructures consist of Fe-silicide. [ABSTRACT FROM AUTHOR]

Using scanning tunneling microscopy, the influence of a thin Au layer on the diffusion of Fe adatoms and the subsequent island nucleation on a Si(111) surface is investigated. The adsorbate induces the $$\hbox{Si(111)-}\sqrt{3}\times \sqrt{3} \hbox{-Au} $$ structure that increases the surface mobility of subsequently deposited Fe atoms, resulting in the formation well-defined nanoclusters. Surprisingly, the domain walls—inherent to the $$\sqrt{3} \times \sqrt{3} \hbox{-Au} $$ reconstruction—do not influence the surface diffusion, which demonstrates that the passivation is of much more importance for the self-assembly than the surface corrugation. Using the decoupling of the diffusion and nucleation on the surface and the reaction with the surface and conventional nucleation theory, the activation energy for surface diffusion Ed = 0.61 eV and the critical cluster size i = 3 are determined, which reveal the microscopic details of the diffusion and nucleation processes. [ABSTRACT FROM AUTHOR]

The role of a Cu buffer layer on the formation of iron silicide nanostructures is investigated using scanning tunneling microscopy and Mössbauer spectroscopy. The deposition of 1 Å Fe on the Si(111)-7×7 and the Si(111)-5×5-Cu surfaces results in the self-organization of nanoscale islands. Increasing the deposition temperature (300-600 °C) leads to an exponential decrease in island density and to an increase of the average island size. At 475 °C, the preferential nucleation site changes from the terrace to the step edges, i.e., step flow growth is observed. The self-assembled nanostructures exhibit the metastable CsCl–FeSi1+x structure. Due to the enhanced diffusion, nanodots formed on the 5×5 surface are significantly larger and more separated compared to growth on the bare 7×7 surface. These results show that a buffer layer provides an additional, experimentally controllable parameter, besides temperature, to tailor the size and distribution of nanodots. [ABSTRACT FROM AUTHOR]