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Struktur Vortrag: Mi., 18:00–18:20 M-V18
Real-time observation of structural and orientational transitions in organic
semiconductor growth
Stefan Kowarik 1,2 , Alexander Gerlach 1,2 , Stefan Sellner 1 , Leide
Cavalcanti 3 , Oleg Konovalov 3 , Frank Schreiber 1
1 Tübingen University, Institute for Applied Physics, 72076 Tübingen, Germany –
2 Oxford University, Physical and Theoretical Chemistry, Oxford OX1 3QZ, UK –
3 ESRF, 38053 Grenoble, France
We use in-situ and real-time X-ray scattering during growth of the organic semiconductor
diindenoperylene to study the kinetically controlled evolution of the film structure
with time. We manage to produce movies of the changes in reflectivity and grazing
incidence diffraction in a relatively broad q range, i.e. beyond simple anti-Bragg-point
time scans during organic molecular beam deposition [1]. These measurements yield
structural and morphological information for a range of film thicknesses. We identify
a transition from layer by layer growth to rapid roughening [2] after 9 MLs for
high temperature growth, subtle changes of the molecular tilt angle, a dynamic change
of the in-plane unit cell dimensions, and competition between standing up and lying
down phases for low temperature growth. Importantly the real-time measurements also
reveal dynamic growth phenomena such as transient structures during growth which
would be missed in simple post-growth measurements.
Fig. 1: Real-time evolution of
the specular reflectivity during
diindenoperylene growth.