Regensburg 2004 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 31: Grenz- und Oberfl

HL 31.1: Vortrag

Mittwoch, 10. März 2004, 16:45–17:00, H14

Theoretical description of the nonlinear optical properties of semiconductor surfaces — •T. Meier1, M. Reichelt1, M. Rohlfing2, C. Voelkmann1, U. Höfer1, and S.W. Koch11Fachbereich Physik und Wissenschaftliches Zentrum für Materialwissenschaften, Philipps-Universität, Renthof 5, D-35032 Marburg — 2School of Engineering and Science, International University Bremen, P.O. Box 750 561, D-28725 Bremen

The description of the nonlinear optical properties of semiconductor surfaces is discussed via two examples. First, a microscopic approach, which uses quasiparticle wavefunctions and dispersions obtained from ab-initio band-structure theory as an input for Bloch equations [1], is presented. Using this method, excitonic effects in the linear absorption spectra of the Si(111)-(2×1) surface are obtained and light-intensity-dependent absorption changes of the surface exciton are predicted.

Second, experiments studying the coherent optically induced dynamics at a Si(001) surface via a five-wave mixing set-up using three ultrashort laser pulses are analyzed using optical Bloch equations. The measurements show an unexpected slow rise of the signal intensity as function of a particular pulse delay which extends well beyond the pulse duration [2]. This response can be described by considering rapid scattering of the photoexcited carriers to other states.

[1] M. Reichelt, T. Meier, S.W. Koch, and M. Rohlfing, Phys. Rev. B 68, 045330 (2003).

[2] C. Voelkmann, M. Reichelt, T. Meier, S.W. Koch, and U. Höfer, submitted.

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