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HL: Fachverband Halbleiterphysik

HL 53: Ultra fast phenomena

HL 53.4: Vortrag

Freitag, 30. März 2007, 11:45–12:00, H15

Theoretical description of the lattice dynamics in laser-excited InSb — •Jessica Walkenhorst, Christian Gilfert, Christian Sippel, Waldemar Töws, Eeuwe Sieds Zijlstra, and Martin Garcia — Theoretische Physik, Fachbereich Naturwissenschaften, Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany

We performed an ab initio study of the softening of optical transverse and longitudinal phonons in InSb due to femtosecond laser excitation. We calculated the frequencies of the optical phonons at the Γ point and at the zone boundary as a function of the number of excited carriers. Our study was based on all-electron density functional calculations. We found an increasing softening of the phonon modes for increasing laser fluence. However, the drop of the studied phonon frequencies did not exceed 30% of the initial value, even for very high excitation energies (electronic temperatures). We concluded that no dramatic flattening of the potential surface occurs, as was suggested by recent experiments.