Berlin 2015 – scientific programme

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DS: Fachverband Dünne Schichten

DS 39: Poster Session II

DS 39.18: Poster

Thursday, March 19, 2015, 16:00–18:30, Poster F

Temperature Induced Phase Transition in Pentacene Thin Films — •Leonard von Helden, Tobias Breuer, and Gregor Witte — Molekulare Festkörperphysik, Philipps Universität Marburg, Renthof 7, D-35032 Marburg, Germany

Pentacene(C₂₂H₁₄) is a widely investigated organic semiconductor and serves as model system for organic thin film growth. It is known to form crystalline thin films in two slightly different, consecutively growing polymorphs on SiO2: the "thin film phase" (TFP) and the "Campbell phase" (CP), i.e. bulk phase.¹ Here we report a study on high temperature dynamics, which was realized by mounting a metal cap on top of the sample under vacuum conditions, providing an unmodified surface of the organic thin film. XRD and AFM measurements prove a phase transition of the TFP into the energetically favored CP, when heated about 40 K beyond its usual desorption point. Moreover we found, that sample contact to ambient air has a tremendous influence on the desorption and transition process.

[1] C. Ambrosch-Draxl et al., New Journal of Physics, 11, 125010, (2009)