Berlin 2024 – scientific programme

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O: Fachverband Oberflächenphysik

O 6: Organic Molecules on Inorganic Substrates I: Adsorption & Growth

O 6.3: Talk

Monday, March 18, 2024, 11:00–11:15, MA 042

Growth of ordered cobalt phthalocyanine monolayers on a terbium modified silicon surface — •Milan Kubicki, Martin Franz, and Mario Dähne — Technische Universität Berlin, Institut für Festkörperphysik, Berlin, Germany

The formation of self-assembled layers of organic molecules on solid surfaces is an important subject because of their possible application in advanced optical and electronic devices. While the formation of self-assembled layers is well established on metal surfaces, the growth on silicon surfaces is much less studied.

On pure silicon surfaces the number of dangling bonds leads to a highly reactive surface and often to rather disordered organic films. The modification of silicon surfaces with thin atomic layers is an interesting alternative. Here, a metallic rare earth silicide monolayer is used as a substrate for the molecular growth.

Using scanning tunneling microscopy and spectroscopy the molecular arrangement and the electronic properties of cobalt phthalocyanine (CoPc) molecules on the TbSi2/Si(111) surface are studied. CoPc belongs to the transition metal phthalocyanines being a class of organic semiconductors, which has been already employed e.g. in organic light emitting diodes, photovoltaic cells, and field-effect transistors.

Our data demonstrate that single CoPc molecules stay mobile at the TbSi2/Si(111) surface at room temperature. By reaching a coverage of a full monolayer a highly ordered film of flat-lying CoPc molecules in different orientations is formed, demonstrating the great potential of rare earth silicides on Si(111) as template for organic film growth.

Keywords: silicon Si(111); rare earth silicides; transition metal phthalocyanines; scanning tunneling microscopy STM; organic monolayers