Imaging and controlling organic molecule adsorption on metal-silicon
surfaces: formation and structure of self-assembled monolayers.
Place: Institute of Physics, Solid Surface Analysis Group. Reichenhainer Strasse 70
Physik-Neubau. UHV STM laboratory. P K08
Supervisor: Dr. Pavel Shukrynau, P176, Tel. 37835, Fax. 837835.
[email protected]
Time: Twice a week.
Introduction: A particularly promising area, and one receiving much attention currently, aims at
constructing hybrid organic molecule–silicon devices in an effort to enhance silicon technology.
An attractive aspect of the organic–silicon approach is that by combining molecular functional
units with existing technology, many complex issues such as physical support and connectivity
may be simplified. In particular, organic molecules deposited onto silicon surfaces have attracted
considerable recent interest, due to the potential of combining the wide range of functionality of
organics with silicon technology for applications ranging from molecular electronics to biosensors.
However, the high reactivity of silicon does not allow direct deposition of organic molecules. An
unwanted organic molecule-Si interaction can be excluded using barrier layer. Pb can be
considered as a good candidate for such a layer, because when deposited on the Si substrate it
provides an exceptionally abrupt, flat and inert interface resulting from the negligibly small
mutual solubility of lead in silicon. In this sense, investigation of deposition process of organic
molecules onto Pb covered silicon (111) substrate is of particular interest for both fundamental
science and technology.
Fig. 1 a): STM image of Si (7x7) surface covered with Pb
demonstrating flat 1x1-Pb island in the middle.
Aim: Variable Temperature Scanning Tunneling Microscopy will be employed to study the early
stages of adsorption of organic molecules onto Pb covered silicon surface Si (111). Dynamics of
single molecules and molecular clusters will be investigated to find the conditions of the formation
of stable surface objects or layers. Scanning Tunneling Spectroscopy will be applied to study local
electronic properties of the objects as a function of their chemical state.
Work program:
1. In situ preparation of silicon 7x7 reconstructed surface by the cycles of UHV annealing up to
1400 K.
2. Deposition of Pb on Si 7x7 surface directly in UHV and prepare 1x1-Pb overlayer by series
of moderate annealing.
3. Deposition and following investigation of organic molecules on this Pb-Si surface.
Key words: Lead, Silicon, Molecular adsorption, Scanning Tunneling Microscopy, Scanning
Tunneling Spectroscopy, Low dimensional structure; Organic molecular engineering.
Literature:
[1] R. Wiesendager and H.-J. Guntherodt, “Scanning Tunneling Microscopy II”, vol. 28, Berlin
Springer Verlag, (1992), p. 99-149.
[2] D.M. Eigler and A. Schweizer, “Positioning Single Atoms with a Scanning Tunneling
Microscope”. Nature 344 (1990), 524-526.
[3] Julian C. Chen, “Introduction to Scanning Tunneling Microscopy”, Oxford University Press:
New York, 1993.
[4] C. Bai, “Scanning Tunneling Microscopy and Its Applications”, Springer-Verlag: Berlin,
Germany, 2000.
Equipment:
Variable Temperature UHV STM, Omicron GmbH, Germany.