Formation and stabilization of Fe-induced magic clusters on Si(1 1 1)-(7 × 7) template |
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Authors: | M.A.K. Zilani |
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Affiliation: | Department of Physics, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore |
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Abstract: | We demonstrate the growth of Fe-induced magic clusters on Si(1 1 1)-(7 × 7) template by in situ scanning tunneling microscopy (STM). These clusters form near a dimer row at one side of the half-unit cell (HUC); and with three different equivalent orientations. A cluster model comprising three top layer Si atoms bonded to six Fe atoms at the next layer in the 7 × 7 faulted-half template is proposed. The optimized cluster structure determined by first-principles total-energy calculation shows an inward-shifting of the three center Fe atoms. The clusters and the nearby center-adatoms of the next HUCs appear with a significantly reduced height below bias voltages 0.4 V in high resolution empty-state STM images, suggesting an energy gap opening near the Fermi level at these localized cluster and adatom sites. We explain the stabilization of the clusters on the 7 × 7 template using the gain in electronic energy as the driving force for cluster formation. |
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Keywords: | Nanostructures Self-assembly Scanning tunneling microscopy Silicon Iron Density functional calculations |
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