Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 36: Postersitzung (Elektronische Struktur, Grenzfl
äche fest-flüssig, Halbleiteroberfl
ächen und -grenzfl
ächen, Nanostrukturen, Oberfl
ächenreaktionen, Teilchen und Cluster, Struktur und Dynamik reiner Oberfl
ächen)

O 36.30: Poster

Montag, 7. März 2005, 15:00–18:00, Poster TU F

BEEM on Ag/Si(111 — •Christian Bobisch, Amin Bannani, and Rolf Möller — Universität Duisburg-Essen, D-45141 Essen, Germany

BEEM (Ballistic Electron Emission Microscopy) is an STM derived method to obtain information on buried metal/semiconductor interfaces. By applying a tunnelling voltage to the tunnelling tip, electrons are injected into a metal film on a semiconducting substrate. Some of them may reach the interface to the semiconductor without loss of energy and pass the Schottky-barrier if the energy exceeds the barrier height. The ballistic electrons contribute to a current that can be detected between the semiconducting-substrate and the independently contacted metal layer. This current is sensitive to various scattering processes leading to an energy dissipation within the metal film and, or at the interface.

In this work the system Ag on Si(111) has been studied. 3-4nm thick Ag films have been grown on the Si-substrate at 150K and annealed at 300 K to obtain a well defined interface. In addition to the topographic STM-data it was possible to obtain laterally resolved information on the electronic structure of the interface. BEES (Ballistic Electron Emission Spectroscopy) was performed to evaluate the local height of the Schottky-barrier. By fitting the obtained I(V) curves with a power law we find a mean barrier height of about 0.71eV.

This work was funded by the SFB616 of the DFG.