Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 49: Ultrafast Phenomena
HL 49.7: Talk
Wednesday, March 28, 2012, 11:00–11:15, EW 202
Time-resolved vibrational dynamics in a single Si3N4 Nanostructure — •Oliver Ristow, Martin Grossmann, Mike Hettich, Elaine Barretto, Martin Schubert, Axel Bruchhausen, Elke Scheer, and Thomas Dekorsy — Departement of Physics and Center of Applied Photonics, University of Constance, D-78457 Konstanz, Germany
In this work we present time domain all-optical investigations of single Si3N4 nanostructures using high-speed asynchronous optical sampling (ASOPS). In order to achieve a high spatial resolution a microscope objective is used with the ASOPS system, which allows for resolving and addressing single nanostructures as well as to scan over large sample areas. We demonstrate the capabilities to investigate two dimensional confined nanostructures, such as nanomechanical systems (NEMS). As one example we show the results of pump-probe experiments analyzing the time-resolved vibrational properties of the nanomechanical resonators’ beam based on Si3N4 and gold. The typical dimensions of such a nanostructure are 100 nm by 100 nm in cross section and 2-3 micron in length. These systems constitute an ideal model system for the investigation of phonon dissipation in NEMS. With this all optical method especially the high frequency range (GHz) is accessible. Due to the high spatial resolution of our system we are able to accurately address different parts of the structures and investigate in the spatial distribution of the different vibrational modes. By combining the measurements with finite element simulations we obtain a good insight on the acoustical dynamics of these structures.