IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Tuesday Sessions
       Session SC+SS-TuA

Paper SC+SS-TuA5
AFM Tip-mediated Nucleation and Growth of Passivated Au Nanocrystal Islands

Tuesday, October 30, 2001, 3:20 pm, Room 122

Session: Semiconductor Nanostructures and Processing
Presenter: P. Moriarty, University of Nottingham, UK
Authors: M.D.R. Taylor, University of Nottingham, UK
P. Moriarty, University of Nottingham, UK
M. Brust, University of Liverpool, UK
Correspondent: Click to Email
Recent molecular dynamics simulations by Luedtke and Landmann@footnote 1@ have highlighted the rich dynamics associated with diffusion of Au clusters on surfaces. However, although there is a significant amount of work related to the diffusion of clusters formed in gas-aggregation (and related) sources, to date there have been no experimental studies of the dynamic properties of passivated Au nanoparticles@footnote 2@ deposited onto a surface from a colloidal suspension. We report non-contact mode and tapping mode (including phase imaging) atomic force microscopy (AFM) observations of the evolution of close-packed layers of 1.5 nm diameter thiol-passivated Au clusters on SiO2. The morphology of 1.5 nm cluster overlayers differs dramatically to that observed for dodecanethiol passivated clusters of 6 nm diameter.@footnote 3@ Furthermore, during each NC-AFM scan dramatic morphological changes occur - faceted holes develop, islands appear and grow, steps change appearance - which we attribute to strong tip-cluster interactions. Dynamic force-distance spectroscopy curves indicate that instabilities in the feedback loop are responsible for significant mass transport during (nominally) non-contact mode AFM scanning. @FootnoteText@ @footnote 1@ Luedtke WD and Landmann U 1999 Phys. Rev. Lett. 82 3835 @footnote 2@ Brust M, Walker M, Bethell D, Schiffrin DJ and Whyman R 1994 J. Chem. Soc., Chem. Comm. 801 @footnote 3@ Fractal Aggregation of Polydisperse Au Nanoclusters on Silicon, M. D. R. Taylor, P. Moriarty and M. Brust, submitted.