We show that the thermal stability of thin films of the organic semiconductor
diindenoperylene (DIP) can be strongly enhanced by aluminum oxide capping
layers. By thermal desorption spectroscopy and in-situ X-ray diffraction we
demonstrate that organic films do not only stay on the substrate, but even
remain crystalline up to 460C, i.e. 270 deg. above their desorption point for
uncapped films (190C). We argue that this strong enhancement of the thermal
stability compared to uncapped and also metal-capped organic layers is related
to the very weak diffusion of aluminum oxide and the structurally well-defined
as-grown interfaces. We discuss possible mechanisms for the eventual breakdown
at high temperatures.Comment: 5 pages, 4 figures, submitted to Adv. Mat., for further information
see http://www.physchem.ox.ac.uk/~f