Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 85: Electron and spin dynamics I
O 85.9: Vortrag
Donnerstag, 17. März 2011, 18:30–18:45, WIL A317
Electronic structure and electron dynamics on Si(001) studied by two-photon photoemission — •Christian Eickhoff1,2 and Martin Weinelt1,2 — 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 Dup and Ddown 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 Ddown; a process also known as surface recombination. Subsequent relaxation of the electrons in the dispersing branch of the dangling-bond band Ddown 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 Ddown band bottom.