Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 13: Ultra-Fast Phenomena
HL 13.3: Vortrag
Dienstag, 6. September 2022, 10:00–10:15, H33
Ultrafast Dynamics of Inter- and Intraband Transitions in GaP Investigated by fs-Time Resolved Ellipsometry — •Rüdiger Schmidt-Grund1, Noah Stiehm1, Erich Runge1, Martin Zahradník2, Shirly Espinoza2, Mateusz Rebarz2, Jakob Andreasson2, and Stefan Krischok1 — 1TU Ilmenau, Technische Physik I and Theoretische Physik I, Weimarer Straße 32, 98693 Ilmenau, Germany — 2ELI Beamlines, Fyzikální ústav AV ČR, Za Radnicí 835, 25241 Dolní Břežany, Czech Republic
We discuss the ultrafast dynamics of the dielectric function after excitation with a high-power laser pulse of the semiconductor GaP in the spectral range around the fundamental absorption edge, measured by pump-probe fs-time resolved spectroscopic ellipsometry [1,2]. The excited hot carriers cause several effects: we observe in different regions of the Brillouin zone both, Pauli-blocking of valence-to-conduction-band transitions and arising of new intra-conduction and -valence-band transitions, enabled by carrier scattering within the Brillouin zone and in particular tunnelling to the indirect minimum. We understand our observations with the help of density functional theory from which we derived band structure, transition matrix elements and the joint density of states between bands energetically relevant in our study. Our results show long lasting non-equilibrium phenomena (>ns), probably due to carrier trapping processes.
[1] S. Richter et al., Rev. Sci. Instrum. 92, 033104 (2021).
[2] S. Richter et al., New J. Phys. 22, 083066 (2020).