Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 21: Optical Properties 1
HL 21.6: Vortrag
Mittwoch, 7. September 2022, 16:30–16:45, H32
Probing free carrier and exciton dynamics in bulk gallium selenide with two-dimensional electronic spectroscopy — •Jonas Allerbeck1,2, Thomas Deckert2, Laurens Spitzner3, and Daniele Brida2 — 1nanotech@surfaces Laboratory, Empa, Überlandstrasse 129, 8600 Dübendorf, Switzerland — 2Department of Physics and Materials Science, Université du Luxembourg, 162a Avenue de la Faïencerie, L-1511 Luxembourg, Luxembourg — 3Department of Physics, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany
Multidimensional optical spectroscopy employing a sequence of three or more pulses is a powerful technique to disentangle energetic correlations. While the technique has been used to study molecular systems, its application to femtosecond dynamics in solid state materials remains new. In this work, we investigate the ultrafast response of excitons and free carriers in the technologically important semiconductor gallium selenide (GaSe) with 10 fs temporal and 1 THz (4 meV) spectral resolution. 2D spectra resolve the excitation energy of broadband pulses and reveal strong bleaching at the exciton resonance, which is hidden by the free carrier response in standard pump-probe measurements, allowing to extract an exciton relaxation time of 112 fs at room temperature. Our quantitative mapping of carrier thermalization shows the interplay of spectral diffusion, induced absorption and dephasing, motivating ongoing theoretical investigation and paving the way for future investigation of quasiparticle correlations in functional material systems.