Regensburg 2016 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 63: Interfaces and Thin Films II (joint session CPP/DY, organized by CPP)

CPP 63.3: Vortrag

Freitag, 11. März 2016, 10:00–10:15, H51

Towards large area atomically flat n-alkane layers: A real-time study of thermal annealing — •Linus Pithan¹, Eduard Meister², Chenyu Jin³, Anton Zykov¹, Wolfgang Brütting², Hans Riegler³, Andreas Opitz¹, and Stefan Kowarik¹ — ¹Inst. f. Physik, Humboldt Universität zu Berlin — ²Inst. f. Physik, Universität Augsburg — ³MPI für Kolloid- und Grenzflächenforschung, Potsdam

Highly anisotropic attachment energies of n-alkanes combined with low surface energies result in their unusual thin films growth and wetting behavior [1]. We analyze the thermal annealing behavior of n-tetratetracontane (TTC, C₄₄H₉₀) in detail with the aim to improve smoothness and to increase the lateral size of crystalline islands of polycrystalline TTC films on SiO, a material system also of interest from a device perspective [2]. We use in situ x-ray diffraction to find an optimum temperature leading to improved texture and crystallinity while avoiding an irreversible phase transition. Further, we employ real-time optical phase contrast microscopy with sub-nm height resolution [3] to track the diffusion of TTC across monomolecular step edges and show that the lateral island sizes increase by more than one order of magnitude from 0.5 µm to 10 µm. This desirable behavior of 2d-Ostwald ripening and the pronounced smoothing we observe is in stark contrast to many other organic molecular films where annealing leads to dewetting, roughening, and a pronounced 3d morphology.

[1] L. Pithan et al., J. Chem. Phys. 143, 164707 (2015)

[2] M. Kraus et al., J. Appl. Phys. 107, 094503 (2010)

[3] R. Köhler et al., Appl. Phys. Lett. 89, 241906 (2006)