Computational studies on small silicon clusters deposited on a graphite substrate

The structural and electronic properties of small silicon clusters adsorbed on a graphite (0001) substrate are studied by Density Functional Theory (DFT) adopting periodic boundary conditions. Monolayer coverage of single Si atoms on the graphite surface is considered as well as the adsorption of Si$_ {n}$ clusters with n = 2, 3. By virtue of covalent bond formation between Si and C, the adsorption of Si$_{n}$ clusters deposited on graphite turns out to be distinctly more stable than that of alkali metal clusters $^{2}$ used as a standard for comparison in the present work. The structure and electronic properties of the Si$_{3}$ cluster are strongly affected by the interaction between adsorbate and substrate. As shown by Density of States (DOS) analysis, the energy gap of the free Si$_{3}$ cluster shrinks due to the influence of the graphite surface. The resulting energy gap of about 0.4 eV is within the experimental range $^{3}$. \\[4pt]$^{2}$K. Rytk\"onen, J. Akola, and M Manninen, Phys. Rev. B {\bf 69}, 205404 (2004); $^{3}$B. Marsen, M. Lonfat, P.Scheier, and K Sattler, Phys. Rev. B {\bf 62}, 6892 (2000).