Regensburg 2004 – scientific programme

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O: Oberflächenphysik

O 44: Elektronische Struktur (Experiment und Theorie) III

O 44.1: Talk

Friday, March 12, 2004, 11:15–11:30, H38

Spectroscopy of ion beam induced electronic excitations at surfaces — •Stefan Meyer¹, Detlef Diesing², and Andreas Wucher¹ — ¹Institut für experimentelle Physik, Universität Duisburg- Essen, 45117 Essen — ²Institut für Schichten und Grenzflächen 3, Forschungszentrum Jülich, 52425 Jülich

We investigate the electronic excitation of a solid surface that is generated by the introduction of kinetic energy in form of fast ion bombardment. In particular, hot electrons are detected which are excited to energies below the work function and therefore cannot leave the surface. The ballistic mean free path of these weakly excited electrons is of the order of 10 nm. The sample is therefore prepared as a 20 nm thin film constituting the front electrode of a metal- insulator- metal tunnel junction. The hot electrons reaching the junction lead to a tunneling current that can be measured. By applying a variable DC- voltage across the junction it is possible to measure the energy distribution of excited electrons, depending on ion beam parameters such as ion energy or ion species.