Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 20: Poster IA (Ultrafast phenomena; Optical properties; Transport; Theory)

HL 20.1: Poster

Monday, March 16, 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. Akimov^1,5, Dmitri R. Yakovlev^1,5, 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.