Speaker
Description
Shirly Espinoza 1, Stefan Zollner 2, Steffen Richter 1, Mateusz Rebarz 1, Oliver Herrfurth 2, Rudiger Schmidt-Grund 2 and Jakob Andreasson 1
1 ELI Beamlines, Institute of Physics, Czech Academy of Science, Na Slovance 2, 18221 Prague, Czech Republic
2 Universität Leipzig, Felix-Bloch-Institut für Festkörperphysik, Linnéstr. 5, 04103 Leipzig, Germany
3 Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003-8001, USA
* shirly.espinoza@eli-beams.eu
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 different ultrafast processes such as carrier generation, band gap renormalization, Burstein-Moss shift, carrier-phonon scattering, carrier-carrier scattering, and phase filing singularities.
This work will present 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 band-filling singularity (Fermi singularity) [1] was observed at around 2.6 eV lasting a few picosenconds.
Acknowledgement
This work was supported by the project Advanced research using high intensity laser produced photons and particles (CZ.02.1.01/0.0/0.0/16_019/0000789) from European Regional Development Fund (ADONIS). This contribution was possible thanks to a EUCALL travel bursary.
References
[1] C. Xu, N.S. Fernando, S. Zollner, J. Kouvetakis, J. Menéndez, Observation of Phase-Filling Singularities in the Optical Dielectric Function of Highly Doped n-Type Ge, Phys. Rev. Lett. 118 (2017) 267402.
