Smoothing and coherent structure formation in organic-organic heterostructure growth

¹ Institut für Angewandte Physik Universität Tübingen - 72076 Tübingen, Germany, EU
² Department of Chemistry, University of California - Berkeley, CA 94720, USA
³ ESRF - 6 Rue Jules Horowitz, BP 220, 38043 Grenoble Cedex 9, France, EU
⁴ Institut für Theoretische Physik, Universität zu Köln - 50937 Köln, Germany, EU

^a alexander.hinderhofer@uni-tuebingen.de

Received: 23 April 2010
Accepted: 13 August 2010

Abstract

We use in situ real-time X-ray reflectivity and complementary atomic force microscopy to monitor crystallinity and roughness evolution during growth of organic heterostructures, i.e. perfluoropentacene (PFP) on diindenoperylene (DIP) and pentacene (PEN) on PFP. For both systems, surface smoothing during thermal evaporation of the second material on top of the first is observed. The smoothing can be rationalized by a, compared to homoepitaxy, lowered step edge barrier for one species diffusing on the other. In addition, we find an exceptionally well-ordered interface for PEN-on-PFP growth and PEN growth with anomalously low roughening, along with coherent scattering over the entire thickness.