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O: Oberflächenphysik

O 6: Hauptvortrag

O 6.1: Hauptvortrag

Montag, 23. März 1998, 14:30–15:00, H36

Deposition of atomic clusters on surfaces — •R.E. Palmer — Nanoscale Physics Research Laboratory, School of Physics and Astrononomy, The University of Birmingham, Birmingham B15 2TT, UK

Size-selected atomic clusters can be regarded as new building blocks for the fabrication of nanostructured materials and devices [1]. The deposition of clusters onto surfaces can thus be regarded as the first stage in the assembly of such materials. Deposition also allows the clusters themselves to be interrogated with the whole panoply of surface physics techniques, making possible measurements which are not practical with dilute gas phase cluster beams.
In this talk I will review experimental studies of the basic processes which govern the deposition of size-selected metal (mainly Ag) clusters on surfaces. The ionised clusters, with size between 3 and 4000 atoms, are mass-selected before controlled deposition in vacuo. The structure of the cluster films is explored with scanning tunnelling microscopy and scanning electron microscopy [2-4], supported by molecular dynamics simulations of the system. The application of high resolution electron energy loss spectroscopy allows us to measure in situ the plasmon modes of clusters deposited in ultra-high-vacuum. Deposition of Ag clusters onto the H-terminated Si(100) surface demonstrates an application of cluster films - as "nanoresists" for dry plasma etching, making possible the production of silicon pillars with diameter of about 10nm [5].
The deposition of (passivated) clusters from solution is a promising route towards the "large scale" production of stable cluster-assembled materials. "Coated" gold clusters with diameter 1-5 nm form well-defined two-dimensional crystalline arrays on graphite and show Coulomb blockade behaviour at room temperature, as revealed by STM studies in ultra-high-vacuum [6]. The clusters can also be manipulated, and their coating removed, by the STM tip [7].

[1] R.E. Palmer, New Scientist 153,38(1977)

[2] I.M. Goldby, L. Kuipers, B. von Issendorff and R.E. Palmer, Appl. Phys. Lett. 69,2819(1996)

[3] S.J. Carroll, P. Weibel, B. von Issendorff, L. Kuipers and R.E. Palmer, J. Phys.: Condens. Matter Letters 8,L617(1996)

[4] S.J. Carroll, K. Seeger and R.E. Palmer, Appl. Phys. Lett., in press.

[5] T. Tada, T. Kanayama, P. Weibel, S.J. Carroll, K. Seeger and R.E. Palmer,Microelectronic Engineering 35293(1997)

[6] P.J. Durston, J. Schmidt, R.E. Palmer and J.P. Wilcoxon, Appl. Phys. Lett. 712940(1997)

[7] P.J. Durston and R.E. Palmer, Appl. Phys. Lett., in press