Advanced Functional Materials

Cover image for Vol. 11 Issue 3

June, 2001

Volume 11, Issue 3

Pages 167–234

    1. Research Initiative “Nanoscience in North Rhine Westphalia” (pages 167–168)

      H. Fuchs and G. Schmid

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<167::AID-ADFM167>3.0.CO;2-H

      A three year research program was launched in 1998 in the state of North Rhine Westphalia in Germany to coordinate academic research activities in the field of “Functional systems with organic/inorganic interfaces”. Some of the results from groups spread over several universities and engineering schools are presented in this issue. The authors of this essay elaborate on the background, the goals, and the organization of the project.

    2. Nanostructured Surfaces (pages 169–173)

      T. Sawitowski, S. Franzka, N. Beyer, M. Levering and G. Schmid

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<169::AID-ADFM169>3.0.CO;2-9

      Unexpected square-shaped structural units (see Figure) are the result of the self-assembly of particles at a phase boundary between water and an organic solvent and subsequent transfer to a solid substrate. This method and the imprinting of surfaces using alumina membranes are discussed for the fabrication of nanostructured surfaces.

    3. Binary Molecular Layers of C60 and Copper Phthalocyanine on Au(111): Self-Organized Nanostructuring (pages 175–178)

      M. Stöhr, T. Wagner, M. Gabriel, B. Weyers and R. Möller

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<175::AID-ADFM175>3.0.CO;2-L

      An eccentric rotation of copper phthalocyanine (CuPc) molecules adsorbed onto an array of hexagonally ordered C60 molecules is unveiled. The behavior of the CuPc molecules at room temperature and at 50 K is studied. Scanning tunneling microscopy images of these molecules (see Figure), as well as of C60, on Au(111) substrates are shown.

    4. The Growth of Transition Metals on H-Passivated Si(111) Substrates (pages 179–185)

      J. O. Hauch, M. Fonine, U. May, R. Calarco, H. Kittur, J. M. Choi, U. Rüdiger and G. Güntherodt

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<179::AID-ADFM179>3.0.CO;2-5

      Cobalt and silver layers on H-passivated Si(111) surfaces have been studied by scanning tunneling microscopy (STM). The authors conclude that such layers will not be suitable for applications in magnetoelectronic devices because of their roughness and inhomogeneity. The Figure shows an STM image of a 200 Å thick Co film on a 200 Å thick Ag buffer layer—with a maze-like structure—on a H-Si(111) substrate.

    5. Controlling Adsorbate Electronic Structure (pages 186–187)

      J. Kliewer, R. Berndt and S. Crampin

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<186::AID-ADFM186>3.0.CO;2-D

      Nanocavities constructed from Mn adatoms on Ag(111) are used here to achieve controlled modification of the electronic structure of the Ag surface. It is demonstrated that the electronic structure of an individual adsorbate is also altered when placed inside a nanocavity (see Figure), thus allowing the adsorbate’s magnetic and chemical properties to be modified in a controllable manner.

    6. Investigation of the Epitaxial Growth of Octamethylene-Tetrathiafulvalene (OMTTF) on Substrates of Different Chemical Reactivity (pages 188–192)

      J. Poppensieker, C. Röthig and H. Fuchs

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<188::AID-ADFM188>3.0.CO;2-5

      How do substrate properties affect superstructures of organic adsorbates? Answering this question was the main aim of the study reported here, in which monolayers of OMTTF (see left-hand part of Figure) were grown on a Ag(100) substrate and on the iodine c(2×2) superstructure on Ag(100). The Figure (right-hand part) also shows how four sulfur atoms per molecule produce a single observable protrusion in scanning tunneling microscopy.

    7. LEED and Optical Spectroscopy Study of an Organic Epitaxial Multilayer Film (pages 193–197)

      A. H. Schäfer, C. Seidel and H. Fuchs

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<193::AID-ADFM193>3.0.CO;2-L

      A fully organic, highly ordered heterolayer system has been prepared and studied. The epitaxial growth of a multilayer of DMe-PTCDI (see Figure) on a phthalocyanine copper(II) complex (CuPc) grown epitaxially on Ag(110) is described. A dose-dependent structural phase transition of the CuPc and a temperature-dependent change of the photoluminescence of the heterolayer are reported and explained.

    8. Field Distribution Within Coaxial Scanning Near-Field Optical Microscope Tips (pages 198–201)

      F. Demming, A. von der Lieth, S. Klein and K. Dickmann

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<198::AID-ADFM198>3.0.CO;2-1

      The stimulation of optical coaxial modes of scanning near-field optical microscope (SNOM) probe tips is described in this paper. These studies unveil that coaxial tips may for certain materials have an improvement over standard tips, and other effects, such as plasma generation in the inner conductor, could lead to a higher transmission. The design of these SNOM tips as well as computer calculations of the field distributions are illustrated and discussed here.

    9. Nanomanipulation of Ligand-Stabilized Au55 Clusters by Means of Scanning Tunneling Microscopy (pages 202–207)

      M. Herrmann, R. Koltun, U. Kreibig, G. Schmid and G. Güntherodt

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<202::AID-ADFM202>3.0.CO;2-K

      A new variant of voltage pulses, field-emission pulses, have been applied to Au55 clusters on highly oriented pyrolytic graphite (HOPG). These pulses cause the partial destruction of cluster shells. “Pearl chains” of clusters (see Figure), attached to step edges, are formed on substrates from which most of the clusters have been removed.

    10. STM Lithography in an Organic Self-Assembled Monolayer (pages 208–212)

      U. Kleineberg, A. Brechling, M. Sundermann and U. Heinzmann

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<208::AID-ADFM208>3.0.CO;2-X

      Nanolithography in dimensions below 70 nm, applicable to metal or semiconductor substrates, is achieved by scanning tunneling microscopy (STM) in self-assembled monolayers of organothiol or organosilane molecules. The Figure shows a cross-grating of 55 nm wide lines etched in biphenylthiol/Au after wet etch transfer.

    11. Oriented Periodic Mesoporous Organosilica (PMO) Film with Organic Functionality Inside the Channel Walls (pages 213–217)

      Ö. Dag, C. Yoshina-Ishii, T. Asefa, M. J. MacLachlan, H. Grondey, N. Coombs and G. A. Ozin

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<213::AID-ADFM213>3.0.CO;2-C

      The first examples of oriented periodic mesoporous organosilica (PMO) films, containing a variety of organic groups (ethane, ethene, benzene, thiophene) inside the channel walls, are reported. Liquid-crystal topological defects in the precursor gels are replicated in the resulting PMO film and are evident in polarized optical microscopy images (see Figure).

    12. Direct Surface Patterning from Solutions: Localized Microchemistry Using a Focused Laser (pages 218–223)

      A. Lachish-Zalait, D. Zbaida, E. Klein and M. Elbaum

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<218::AID-ADFM218>3.0.CO;2-T

      Microscale-patterned surfaces are created by direct-write lithography using a tightly focused, low-power, infrared laser beam, applied to a homogeneous precursor solution and focussed on the substrate–solution interface. The morphology and physical properties of the patterns can be altered by the use of capping agents during deposition or by further chemical reactions after deposition. The Figure shows a Ag–PVP (polyvinylpyrrolidone) grid.

    13. An Efficient Chemical Solution Deposition Method for Epitaxial Gallium Nitride Layers Using a Single-Molecule Precursor (pages 224–228)

      H. Parala, A. Devi, A. Wohlfart, M. Winter and R. A. Fischer

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<224::AID-ADFM224>3.0.CO;2-4

      Chemical solution deposition (CSD) is a simple, very cost-effective method of thin-film fabrication. However, little is known about CSD of metal hydrides. It is demonstrated that CSD of GaN using molecular precursors is feasible and that the choice of precursor and processing conditions significantly affects the morphology and crystallization behavior of the resulting films: the GaN film in the Figure was grown on c-plane Al2O3 at 800 °C.

    14. Optical Signature of Delocalized Polarons in Conjugated Polymers (pages 229–234)

      D. Beljonne, J. Cornil, H. Sirringhaus, P. J. Brown, M. Shkunov, R. H. Friend and J.-L. Brédas

      Version of Record online: 31 MAY 2001 | DOI: 10.1002/1616-3028(200106)11:3<229::AID-ADFM229>3.0.CO;2-L

      Good contacts between adjacent conjugated chains in the solid are required for efficient charge transport in polymer-based devices. Here quantum-chemical calculations are performed on two-chain aggregates of the model five-ring oligomer shown in the Figure to assess the influence of interchain interactions on the nature of singly charged species in organic conjugated polymers. Comparison is made with optical charge modulation spectroscopic data.