AVS 47th International Symposium
    Processing at the Nanoscale/NANO 6 Thursday Sessions
       Session NS+NANO6-ThM

Paper NS+NANO6-ThM1
Implantation and Pinning of Size-selected Ag Nanoclusters at the Graphite Surface

Thursday, October 5, 2000, 8:20 am, Room 302

Session: Nanostructured Materials
Presenter: R.E. Palmer, The University of Birmingham, UK
Authors: S. Pratontep, The University of Birmingham, UK
S.J. Carroll, The University of Birmingham, UK
M. Streun, The University of Birmingham, UK
P.D. Nellist, The University of Birmingham, UK
R.E. Palmer, The University of Birmingham, UK
S. Hobday, Loughborough University, UK
R. Smith, Loughborough University, UK
Correspondent: Click to Email
Size-selected nanoclusters provide building blocks for creating nanoscale structures. However, the deposition of such clusters on surfaces is often susceptible to surface diffusion and thus aggregation of clusters. We have investigated the deposition of size-selected Ag@sub N@@super +@ clusters (N=20-200) on graphite at elevated impact energies (E=0.25-6 keV). Molecular dynamics simulations establish two energy regimes in which lateral diffusion of the deposited clusters is inhibited.@footnote 1@ At high impact energies (> 20 eV/atom) the clusters are found to penetrate into the surface and come to rest at the bottom of an open tunnel so created. The implantation depth is found to vary linearly as E/N@super 2/3@. This implies a constant decelerating force which is proportional to the cross-sectional area, rather than the volume, of the cluster. At lower impact energies (~10 eV/atom) we have found a size-dependent threshold energy above which the cluster is pinned on the surface at the impact site via the creation of a point defect. This threshold exhibits a linear dependence with the cluster size, N. This prediction is confirmed by scanning tunnelling microscopy (STM) investigations of cluster pinning as a function of cluster size and impact energy. Both the implantation and the pinning behaviour suggest viable methods for the fabrication of well-defined nanostructured surfaces. @FootnoteText@ @footnote 1@ S.J. Carroll, P.D. Nellist, R.E. Palmer, S. Hobday and R. Smith, Phys. Rev. Lett. 84, 2654 (2000).