Ultrafast dynamics of hot charge carriers in an oxide semiconductor probed by femtosecond spectroscopic ellipsometry

0538509 - FZÚ 2021 RIV GB eng J - Journal Article
Richter, Steffen - Herrfurth, O. - Espinoza Herrera, Shirly J. - Rebarz, Mateusz - Kloz, Miroslav - Leveillee, J.A. - Schleife, A. - Zollner, S. - Grundmann, M. - Andreasson, Jakob - Schmidt-Grund, R.
Ultrafast dynamics of hot charge carriers in an oxide semiconductor probed by femtosecond spectroscopic ellipsometry.
New Journal of Physics. Roč. 22, č. 8 (2020), s. 1-15, č. článku 083066. ISSN 1367-2630. E-ISSN 1367-2630
R&D Projects: GA MŠMT EF16_019/0000789; GA MŠMT EF15_003/0000447; GA MŠMT LQ1606
Grant - others:OP VVV - ADONIS(XE) CZ.02.1.01/0.0/0.0/16_019/0000789; OP VVV - ELIBIO(XE) CZ.02.1.01/0.0/0.0/15_003/0000447
Research Infrastructure: ELI Beamlines III - 90141
Institutional support: RVO:68378271
Keywords : ZnO * time-resolved ellipsometry * ultrafast dynamics * thin oxides * oxide * semiconductor * dielectric function
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 3.732, year: 2020
Method of publishing: Open access

Many linked processes occur concurrently in strongly excited semiconductors, such as interband and intraband absorption, scattering of electrons and holes by the heated lattice, Pauli blocking, bandgap renormalization and the formation of Mahan excitons. In this work, we disentangle their dynamics and contributions to the optical response of a ZnO thin film. Using broadband pump-probe ellipsometry, we can directly and unambiguously obtain the real and imaginary part of the transient dielectric function which we compare with first-principles simulations. We find interband and excitonic absorption partially blocked and screened by the photo-excited electron occupation of the conduction band and hole occupation of the valence band (absorption bleaching). Exciton absorption turns spectrally narrower upon pumping and sustains the Mott transition, indicating Mahan excitons.
Permanent Link: http://hdl.handle.net/11104/0316308