Berlin 2012 – scientific programme
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DS: Fachverband Dünne Schichten
DS 37: Poster II: Focused electron beam induced processing for the fabrication of nanostructures (focused session, jointly with O); Nanoengineered thin films; Layer properties: electrical, optical, and mechanical properties; Thin film characterization: structure analysis and composition (XRD, TEM, XPS, SIMS, RBS,..); Application of thin films
DS 37.7: Poster
Thursday, March 29, 2012, 15:00–17:00, Poster E
Mode Shape and Dispersion Relation of bending Waves in thin Silicon Membranes — •Reimar Waitz1, Stephan Nößner1, Michael Hertkorn1, Olivier Schecker1,2, and Elke Scheer1 — 1Universität Konstanz — 2now at: Robert Bosch GmBH
We study the vibrational behavior of silicon membranes with a thickness in the range of a few hundred nanometers and macroscopic lateral size. A piezo is used to couple in transverse vibrations, which we monitor with a phase-shift interferometer using stroboscopic light.The observed wave pattern of the membrane deflection is a superposition of the mode corresponding to the excitation frequency and several higher harmonics. Using a Fourier transformation in time, we separate these contributions and image up to the 8th harmonic of the excitation frequency. With this method we determine the dispersion relation of membrane oscillations in a frequency range up to 12 MHz. We develop a simple analytical model combining stress of a membrane and bending of a thin plate that describes both the experimental data and finite-elements simulations very well. We derive correction terms to account for a finite curvature of the membrane and for the inertia of the surrounding atmosphere. A simple criterion for the transition between stressed membrane and thin plate behavior is presented.