Morphology and electronic properties of the pentacene on cobalt interface

In this paper, we report the structural and electronic properties of pentacene thin films grown on a polycryst. Co film using at. force microscopy and UV photoemission spectroscopy (UPS), resp. Investigation of this type of interface is of importance for the engineering of hybrid organometallic spintronic devices for which the use of spin polarized electrodes is a prerequisite. Uniform single cryst. areas of pentacene as large as several micrometers, with mols. arranging almost perpendicular to the substrate, were obtained. For the electronic properties at this interface, we have found an energy barrier for the hole injection of about 1 eV, in spite of the fact that the ionization potential of pentacene reported previously equals the work function of Co. A shift of the vacuum level of the same magnitude has also been obsd. A comparison of the UPS spectra of the pentacene films with the gas phase spectrum directly indicates that hybridization effects are present at this interface. [on SciFinder (R)]