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DS: Fachverband Dünne Schichten
DS 28: Layer Properties: Electrical, Optical, and Mechanical Properties
DS 28.9: Vortrag
Donnerstag, 14. März 2013, 11:45–12:00, H8
Generation of a broadband acoustic frequency comb in the 100 GHz-range — •Martin Großmann1, Oliver Ristow1, Mike Hettich1, Chuan He1, Reimar Waitz1, Patricia Scheel1, Axel Bruchhausen2, Martin Schubert1, Vitaly Gusev3, Elke Scheer1, and Thomas Dekorsy1 — 1Department of Physics, University of Konstanz, D-78467 Germany — 2Instituto Balseiro & Centro Atómico Bariloche (CNEA), and CONICET, Argentina — 3Institut des Molécules et Matériaux du Mans, UMR CNRS 6283, Université du Maine,France
Acoustic properties in the GHz frequency range are not very well understood for most semiconductors although intrinsic attenuation and scattering at interfaces of acoustic waves is of great interest for both fundamental and applied science. Additionally adhesion properties of very thin films are both hard to control and to evaluate. A thin Al/Si-membrane which is investigated by asynchronous optical sampling, a pump-probe technique, can be used to gain knowledge of these crucial properties. The cavity-like behavior for acoustic pulses of the membrane is used to generate a frequency comb in the 100 GHz range consisting of 24 eigenmodes. By analyzing the Fourier spectrum of the generated acoustic pulse we can evaluate the adhesion of the two layer system and by analyzing the individual reflected pulses, frequency dependent damping constants can be extracted for frequencies up to 300 GHz. Furthermore a frequency shift of the higher harmonics from the expected values given by the ground mode due to the two-layer system is measured.