Title: Structure and energetics of silicon clusters adsorbed on the Au(111) surface: a first principles study

Authors: Sudip Chakraborty, S.V. Ghaisas, Chiranjib Majumder

Addresses: Department of Electronic Science, University of Pune, Pune 411 007, India; Chemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India. ' Department of Electronic Science, University of Pune, Pune 411 007, India. ' Chemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India

Abstract: We report an extensive first-principles investigation of the structure and electronic properties of small Si _n (n = 1, 2, 3, 4, and 6) clusters deposited on the Au(111) surface. The calculations were performed using a plane wave based pseudopotential method under the framework of density functional theory. The electron-ion interaction energy has been described using ultrasoft pseudopotentials (USPP) and the spin polarised GGA scheme was used for the exchange correlation energy. The results reveal that Si atom prefers to adsorb on the hcp site of the Au(111) surface with strong binding energy. For Si₃, the closed triangle geometry of the bare cluster forms an open triangle by rupturing one of the three Si-Si bonds. Remarkable structural changes in the gas phase geometries were observed from Si₄ onwards. For example, while the adsorption of rhombus in parallel and perpendicular orientation to the surface plane remains almost unaltered, the tetrahedral conformation becomes almost flat by the interaction of Au surface. The nature of chemical bonding between Au surface and Si clusters was investigated from the charge distribution analysis and the electronic density of states (EDOS). Based on charge distribution analysis it is found that Si atoms transfer charges to the Au surface. Based on the results it is inferred that Si clusters deposition on the Au surface involves large energy release and would lead to coat the surface by spill over of Si atoms rather than island formation.

Keywords: gold surfaces; silicon clusters; adsorption; electronic density of states; binding energy; charge transfer; Au surfaces; density functional theory; ultrasoft pseudopotentials; chemical bonding; charge distribution; energy release; nanotechnology.

DOI: 10.1504/IJNT.2010.034691

International Journal of Nanotechnology, 2010 Vol.7 No.9/10/11/12, pp.833 - 842

Published online: 17 Aug 2010 *

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