Chain-length dependent growth dynamics of n-alkanes on silica investigated by energy-dispersive x-ray reflectivity in situ and in real-time

Journal Article · Mon May 28 04:00:00 EDT 2012 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4719530· OSTI ID:22047221

Weber, C; Rukat, T; Schaefer, P; Kowarik, S ^[1]; Frank, C; Schreiber, F ^[2]; Bommel, S ^[1]; Leitenberger, W ^[3]

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1. Institut fuer Physik, Humboldt-Universitaet zu Berlin, Newtonstr. 15, 12489 Berlin (Germany)
2. Institut fuer Angewandte Physik, Universitaet Tuebingen, Auf der Morgenstelle 10, 72076 Tuebingen (Germany)
3. Institut fuer Physik, Universitaet Potsdam, Karl-Liebknecht-Strasse 24/25,14476 Potsdam-Golm (Germany)

We compare the growth dynamics of the three n-alkanes C{sub 36}H{sub 74}, C{sub 40}H{sub 82}, and C{sub 44}H{sub 90} on SiO{sub 2} using real-time and in situ energy-dispersive x-ray reflectivity. All molecules investigated align in an upright-standing orientation on the substrate and exhibit a transition from layer-by-layer growth to island growth after about 4 monolayers under the conditions employed. Simultaneous fits of the reflected intensity at five distinct points in reciprocal space show that films formed by longer n-alkanes roughen faster during growth. This behavior can be explained by a chain-length dependent height of the Ehrlich-Schwoebel barrier. Further x-ray diffraction measurements after growth indicate that films consisting of longer n-alkanes also incorporate more lying-down molecules in the top region. While the results reveal behavior typical for chain-like molecules, the findings can also be useful for the optimization of organic field effect transistors where smooth interlayers of n-alkanes without coexistence of two or more molecular orientations are required.

• OSTI ID: 22047221
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 20 Vol. 136; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ALKANES
CHEMICAL ANALYSIS
FIELD EFFECT TRANSISTORS
LAYERS
REFLECTIVITY
SILICA
SILICON OXIDES
SUBSTRATES
THIN FILMS
X RADIATION
X-RAY DIFFRACTION