Transient birefringence and dichroism in ZnO studied with fs-time-resolved spectroscopic ellipsometry

0547598 - FZÚ 2022 RIV US eng J - Journal Article
Herrfurth, O. - Richter, Steffen - Rebarz, Mateusz - Espinoza Herrera, Shirly J. - Zuniga-Perez, J. - Deparis, Ch. - Leveillee, J.A. - Schleife, A. - Grundmann, M. - Andreasson, Jakob - Schmidt-Grund, R.
Transient birefringence and dichroism in ZnO studied with fs-time-resolved spectroscopic ellipsometry.
Physical Review Research. Roč. 3, č. 1 (2021), č. článku 013246. E-ISSN 2643-1564
R&D Projects: GA MŠMT EF16_019/0000789; GA MŠMT EF15_003/0000447
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 : absorption * transitions * parameters * excitons * semiconductors * intensity * dynamics * rule
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Method of publishing: Open access

The full transient dielectric-function (DF) tensor of ZnO after UV-laser excitation in the spectral range 1.4-3.6 eV is obtained by measuring an m-plane-oriented ZnO thin film with femtosecond (fs)-time-resolved spectroscopic ellipsometry. From the merits of the method, we can distinguish between changes in the real and the imaginary part of the DF as well as changes in birefringence and dichroism, respectively. We find pump-induced switching from positive to negative birefringence in almost the entire measured spectral range for about 1 ps. Simultaneously, weak dichroism in the spectral range below 3.0 eV hints at contributions of inter-valence-band transitions. Line-shape analysis of the DF above the band gap based on discrete exciton, exciton-continuum, and exciton-phonon-complex contributions shows a maximal dynamic increase in the transient exciton energy by 80 meV. The absorption coefficient below the band gap reveals an exponential line shape attributed to Urbach-rule absorption mediated by exciton-longitudinal-optic-phonon interaction.
Permanent Link: http://hdl.handle.net/11104/0323810