Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 20: Poster IA (Ultrafast phenomena; Optical properties; Transport; Theory)
HL 20.1: Poster
Montag, 16. März 2015, 15:00–20:00, Poster B
Laser induced Tellurium formation detected by THz oscillations in plasmonic crystals — •Jonas Vondran1, Lars E. Kreilkamp1, Martin Pohl1, Maciej Wiater2, Tomasz Wojtowicz2, Grzegorz Karczewski2, Boris. A Glavin3, Leonid Litvin4, Axel Rudzinski4, Michael Kahl4, Ilya A. Akimov1,5, Dmitri R. Yakovlev1,5, and Manfred Bayer1 — 1Experimentelle Physik 2, Technische Universität Dortmund, D-44221 Dortmund, Germany — 2Institute of Physics, Polish Academy of Sciences, PL-02668 Warsaw, Poland — 3Lashkaryov Institute of Semiconductor Physics, 03028 Kyiv, Ukraine — 4Raith GmbH, Konrad-Adenauer-Allee 8, 44263 Dortmund, Germany — 5A. F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
We study the differential reflectivity of a CdMgTe structure in pump-probe experiments on a femtosecond timescale under below bandgap excitation. In the transient data oscillations with frequencies in the 3.6 - 3.8 THz range are observed. We attribute this to coherent oscillation of optical phonons in a thin Tellurium layer on the sample surface which is formed on the II-VI semiconductor due to a surface reconstruction induced by the pump beam. Changes in frequency and amplitude with increasing exposure time allow to monitor the build-up process of the Tellurium layer.
We show that the oscillatory signal is enhanced by one order of magnitude via patterning of a plasmonic grating with a period of several hundreds of nanometers.