Berlin 2018 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 26: Ultra-fast phenomena
HL 26.13: Talk
Wednesday, March 14, 2018, 12:45–13:00, EW 202
Phase-Filling Singularities in Femtosecond Transient Dielectric Spectra of Germanium — •Shirly Espinoza1, Mateusz Rebarz1, Steffen Richter1, Oliver Herrfurth2, Miroslav Kloz1, Rudiger Schmidt-Grund2, Jakob Andreasson1, and Stefan Zollner3 — 1ELI Beamlines, Institute of Physics, Czech Academy of Science, Na Slovance 2, 18221 Prague, Czech Republic — 2Universität Leipzig, Felix-Bloch-Institut für Festkörperphysik, Linnéstr. 5, 04103 Leipzig, Germany — 3Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003-8001, USA
By exciting semiconductors with ultra-short laser pulses and studying the non-equilibrium material, information about the band structure and the dynamics of the generation and relaxation of carriers can be obtained. Time-resolved ellipsometry allows the measurements of changes in the dielectric function of solid state materials in the femtosecond time-scale. In semiconductors, these changes can be assigned to several ultrafast processes such as carrier generation, band gap renormalization, Burstein-Moss shift, carrier-phonon scattering, carrier-carrier scattering, and phase filing singularities. This work presents recent results on femtosecond transient dielectric spectra of undoped Germanium at room temperature. The carriers were generated by the excitation with a 1.55 eV laser beam. The predicted Fermi singularity (Xu et al., Phys.Rev.Lett.118, 2017, 267402) was observed lasting a few picosenconds.