Regensburg 2022 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 13: Ultra-Fast Phenomena
HL 13.2: Talk
Tuesday, September 6, 2022, 09:45–10:00, H33
Studying hot electron transport in bismuth with transient all optical pump-probe spectrocopy — •Fabian Thiemann1, Germán Sciaini2, Alexander Kaßen1, and Michael Horn-von Hoegen1 — 1University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany — 2University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
Bismuth as a Peierls-Jones distorted semimetal is famous for its photoexcited coherent optical phonon modes and its delicate interplay with the electron dynamics. Especially the A1g phonon mode at ≈ 3 THz and its characteristic softening upon photoexcitation is easily accessible and can be studied with all optical pump-probe spectroscopy, solely by monitoring the change in reflectivity Δ R/R0. The number of excited carriers in bismuth influences the atomic potential energy surface and thus the mode’s softening. Therefore, in turn, we employed the redshift of the A1g mode as a robust quantity to determine the spatial distribution of excited carriers and the absorbed energy density in the carrier system. A homogenous distribution due to ultrafast transport of hot carriers was observed, limited by an effective carrier penetration depth that is way beyond the optical skin depth.