Hostname: page-component-7bb8b95d7b-nptnm Total loading time: 0 Render date: 2024-09-19T03:04:27.516Z Has data issue: false hasContentIssue false

Electrochemical Heteroepitaxial Growth of Molecular Films on Ordered Substrates

Published online by Cambridge University Press:  10 February 2011

Julie A. Last
Affiliation:
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455
Daniel E. Hooks
Affiliation:
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455
Christopher M. Yip
Affiliation:
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455
Michael D. Ward
Affiliation:
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455
Get access

Abstract

Electrocrystallization of the organic superconductor bis(ethylenedithio)tetrathiafulvalene triiodide, (ET)2I3, on a highly ordered pyrolytic graphite (HOPG) substrate has been visualized using in situ atomic force microscopy (AFM). Previous studies have revealed the formation of a coincident epitaxial monolayer with a structure identical to that of a (001) layer of the superconducting beta phase of this material prior to bulk crystal growth. However, the symmetry of the HOPG substrate leads to domain boundary defects during self assembly of the separately growing domains. The number of defects is significantly reduced after an electrochemical annealing process in which the potential is cycled about the monolayer deposition potential. Annealing of these films is important if they are to be used in electronic devices as the defects may serve as barriers to electron transport in the two-dimensional layers.

In addition to (ET)2I3, monolayer growth also has been visualized during electrocrystallization of (ET)2ReO4 on HOPG. The role of coincident epitaxy with HOPG in the monolayer formation and molecular orientation will be discussed.

Structurally modified substrates have also been investigated. Studies of the electrocrystallization of (ET)2I3 on HOPG, thermally treated to produce well-defined monolayer depth pit structures, have demonstrated that (ET)2I3 monolayer growth can occur inside the pit structures. The presence of monolayer domain boundaries within large pits indicates that multiple, independent nucleation events can occur in the pits, providing an opportunity to determine critical nucleation sizes by varying the pit dimensions. Recently we have discovered that MoS2 substrates can be electrochemically etched, giving rise to monolayer deep triangular pits.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1 (a) Molecular Electronic Devices, Carter, F., Ed. (Marcel Dekker, New York, 1982).Google Scholar
(b) Molecular Electronics, Ashwell, G., Ed. (John Wiley and Sons. New York, 1992).Google Scholar
2 Uhlman, A., Scaringe, R.P., Langmuir 8, 894 (1992).Google Scholar
3 (a) Hossick-Schott, J., Ward, M.D., J. Am. Chem. Soc. 116, 6806 (1994).Google Scholar
(b) Hossick-Schott, J., Yip, C.M., Ward, M.D., Langmuir 11, 177 (1995).Google Scholar
(c) Hillier, A.C., Maxson, J.B., Ward, M.D., Chem. Mater. 6, 2222 (1994).Google Scholar
(d) Hillier, A.C., Hossick-Schott, J., Adv. Mater. 7, 409 (1995).Google Scholar
4 Unertl, W., in Scanning Tunneling Microscopy and Spectroscopy Theory. Techniques, and Applications, edited by Bonnell, D.A. (VCH Publishers, Inc., New York, 1993), p. 115.Google Scholar
5 Hillier, A.C., Ward, M.D., Phys. Rev. B, in press.Google Scholar
6 Overney, R. M., Meyer, E., Frommer, J., Guntherodt, H. J., Fujihara, M., Takano, H., Gotoh, Y., Langmuir 10, 1281 (1994).Google Scholar
7 Xiao, X., Hu, J., Charych, D.H., Salmeron, M., Langmuir 12, 2359 (1996).Google Scholar
8 Ohring, M., The Materials Science of Thin Films (Academic Press. Inc., New York, 1992).Google Scholar
9 Last, J.A., Ward, M.D., Advanced Materials 8 (9), 730 (1996).Google Scholar
10 Evans., E.L.; Griffiths, R. J. M.; Thomas, J.M. Science 171, 174 (1970).Google Scholar
11 Yang, R.T.; Wong, C. J. Chem. Phys. 75(9), 4471 (1981).Google Scholar
12 Patrick, D.L.; Cee, V.J.; Beebe , Jr, T.P. Science 265, 231 (1994).Google Scholar
13 Ignatz was the brick-tossing sidekick of Krazy Kat, the subjects of a cartoon strip written by George Harriman and published daily between 1918 – 1941.Google Scholar
14 (a) Ed Delawski, and Parkinson, B. A., J. Am. Chem. Soc. 114 1661 (1992).Google Scholar
(b) Parkinson, B. A., J. Am. Chem. Soc. 112 7498 (1990).Google Scholar