| Autor: |
Michael G. Ramsey, J. Ivanco, Thomas Haber, Roland Resel |
| Rok vydání: |
2008 |
| Předmět: |
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| Zdroj: |
Journal of Crystal Growth. 310:101-109 |
| ISSN: |
0022-0248 |
| DOI: |
10.1016/j.jcrysgro.2007.10.018 |
| Popis: |
This is a report on sexithiophene thin films (6–300 A) grown on TiO 2 (1 1 0) single crystal surfaces. The films are investigated by atomic force microscopy and both laboratory and synchrotron X-ray diffraction techniques. Different growth stages are identified: after the formation of a first lying monolayer, small clusters are formed. Thicker films show needle like morphologies with two distinct needle directions. The morphology can be assigned to the obtained crystal alignments and a growth model is derived: the oxygen rows of the surface direct the alignment of initially adsorbed molecules parallel to the surface corrugation. Further molecules form small clusters on top of this monolayer. At a sufficient cluster size they merge and crystallize in the so-called low temperature phase with the contact plane {0 1 0} having a mosaicity of 1– 2 ∘ . Furthermore, the observed crystallites show a distinct in-plane alignment, with a distribution of few degrees which perfectly explains the two needle directions. However, the molecules of the crystallites are slightly rotated to the oxygen rows, which is ascribed to a lattice match effect. Therefore it is concluded that the molecules of the monolayer are integrated in the crystal structure and undergo a slight realignment during 3D crystal growth. Finally the importance of an atomically ordered substrate surface is illustrated by a comparison to a film grown on an intentionally disordered surface leading to standing molecules without in-plane order. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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Full Text from ScienceDirect