Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)
O 36.96: Poster
Dienstag, 15. März 2011, 18:30–22:00, P4
Hot phonons in the relaxation dynamics at the Si(001) surface — •Thi Uyen-Khanh Dang1, Christian Eickhoff2,3, Martin Weinelt2,3, Andreas Knorr1, and Carsten Weber1 — 1Institut für Theoretische Physik, Technische Universität Berlin, Germany — 2Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Berlin, Germany — 3Freie Universität Berlin, Fachbereich Physik, Berlin, Germany
We investigate the relaxation dynamics of photo-excited carriers at the Si(001) surface. Relaxation occurs mainly from the bulk conduction band into the surface state Ddown. We present time-resolved experimental results on the relaxation dynamics obtained via two-photon photoemission measurements. The results are compared to theoretical calculations based on the Bloch-Boltzmann-Peierls approach, where the influences of electron-phonon and electron-electron scattering are analyzed. We find that the electronic temperature remains well above the equilibrium lattice temperature for times much longer than the typical scattering times of the system (even after 10 ps). This is found to be due to strong heating of LO phonon modes due to electron relaxation in the bulk via LO phonon emission. The different contributions of the scattering channels as well as phonon bottleneck effects are discussed.