Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 85: Electron and spin dynamics I

O 85.9: Talk

Thursday, March 17, 2011, 18:30–18:45, WIL A317

Electronic structure and electron dynamics on Si(001) studied by two-photon photoemission — •Christian Eickhoff^1,2 and Martin Weinelt^1,2 — ¹Max-Born-Institut, Max-Born-Straße 2a, 12489 Berlin, Germany — ²Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany

In this talk we will give an overview on the electron dynamics at the Si(001) surface. In the first part we will present new aspects regarding the electronic structure of the silicon surface. The temperature dependent changes in the binding energies of the dangling-bond surface states D_up and D_down and of the ionization energy will be discussed. In the second part we will highlight the rich variety of carrier dynamics in the conduction band which we access in a femtosecond pump-probe photoemission experiment using an electron analyzer with 2D-CCD-detector. Starting with the relaxation of photoinduced carriers in the Γ₁₅- and X₁-valley we followed the scattering pathway of carriers to the normally unoccupied surface state D_down; a process also known as surface recombination. Subsequent relaxation of the electrons in the dispersing branch of the dangling-bond band D_down by electron-phonon scattering is slowed down when reaching the band minimum. This is attributed to the blockade of optical phonon emission close to the D_down band bottom.