Regensburg 2016 – scientific programme

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DS: Fachverband Dünne Schichten

DS 55: Organic Thin Films III

DS 55.4: Talk

Friday, March 11, 2016, 10:15–10:30, H8

The energy level alignment at the interfaces of CoPc with ferromagnetic substrates studied by ultraviolet and inverse photoemission spectroscopies — •Jing Guo, Volodymyr Dzhagan, Georgeta Salvan, and Dietrich R.T. Zahn — Semiconductor Physics, Technische Universität Chemnitz, 09107 Chemnitz Germany

Metal-organic interfaces play a crucial role for the ever growing field of organic spintronics. Here the electronic structure of the interface between a CoPc thin film and Co or Ni foils as substrates is investigated by ultraviolet photoemission spectroscopy (UPS) and inverse photoemission spectroscopy (IPES). Both HOMO and LUMO positions of CoPc are noticeably dependent on the CoPc film thickness. Due to the image charge screening effect induced by the metallic substrate, the positions of LUMO and HOMO both shift towards lower binding energy at the interface. In addition, an interfacial state is supposed to form at the CoPc/Co interface, but not in the case of the CoPc/Ni interface. As a result, the transport band gap of CoPc on Co foil "opens" from (1.3±0.3) eV at 1 nm film thickness up to (2.2±0.3) eV above 6 nm film thickness. But for CoPc on Ni foil, its "opening" is much less pronounced from (1.9±0.3) eV to (2.2±0.3) eV. This different energetic behaviour at these interfaces is important for designing the electronic and spintronic devices.