Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 63: Ultrakurzzeitph
änomene

HL 63.1: Vortrag

Mittwoch, 9. März 2005, 10:45–11:00, TU P-N201

Theory of two photon photo emission at semiconductor surfaces — •Norbert Bücking, Andreas Zeiser, and Andreas Knorr — Nichtlineare Optik und Quantenelektronik, PN 7-1, Institut für Theoretische Physik, TU Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

Recent time resolved Photoemission experiments on InP surfaces yield spectra with a two peak shape and a characteristic decay rate of 200 fs. This shape implies the existence of a surface band energetically close to the bulk conduction band, coupled through many particle interaction.

A system of four bands, including bulk valence, bulk conduction, surface conduction and free electrons is set up to dynamically model electronic transitions at the surface. Density matrix formalism is used to calculate the dynamics of the transitions and the population inside the bands [1]. By this approach, the experimental two peak spectra can be reproduced and it is shown that the measured decay rates may be obtained by the choice of realistic parameters.

[1] A. Zeiser, N. Bücking, J. Götte, J. Förstner, P. Hahn, W. G. Schmidt and A. Knorr, "Dynamics of the phonon-induced electron transfer between semiconductor bulk and surface states", phys. stat. sol (b) 241,No. 12, R60-R62, (2004)