Regensburg 2022 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 13: Ultra-Fast Phenomena
HL 13.9: Talk
Tuesday, September 6, 2022, 11:45–12:00, H33
Time-resolved ellipsometry on CuI thin films — •Carola Emminger1,2, Evgeny Krüger1, Michael Bar1, Shirly Espinoza3, Martin Zahradnik3, Mateusz Rebarz3, Felix-Florian Delatowski3, Jakob Andreasson3, Michael Seifert4, Silvana Botti4, Chris Sturm1, and Marius Grundmann1 — 1Felix-Bloch Institut für Festkörperphysik, Universität Leipzig, Germany — 2Institut für Physik, Humboldt-Universität zu Berlin, Germany — 3ELI Beamlines, Czech Republic — 4Institut für Festkörpertheorie und Optik, Friedrich-Schiller-Universität Jena, Germany
We report the impact of the carrier dynamics on the dielectric function of CuI thin films by means of femtosecond pump-probe spectroscopic ellipsometry. As expected, we observe a strong decrease of the exciton peak due to the pump pulse, which starts to recover after 200-300 fs. Interestingly, we notice a small increase in absorption below the band gap after a delay time of about 400 fs, which might be explained by valence- to valence-band transitions resulting from the laser-induced increased carrier density. At about 10 ps, the dielectric function has almost fully recovered. We analyze the delay-time dependent dielectric function and discuss possible explanations for the changes related to the carrier density.