Quasi longitudinal Lamb acoustic modes along ZnO/Si/ZnO structures.
A novel structure consisting of a Si plate sandwiched between two ZnO layers is suggested as propagation medium for Quasi Longitudinal (QL) acoustic Lamb waves. Considering a low-dispersive quasi-longitudinal mode as an example, the phase velocity v, electromechanical coupling constant k2and mechanical displacements U1, U3versus plate and ZnO layers thicknesses have been calculated starting from uncoated plate through the same plate with one layer to the plate with two layers onto opposite faces. A remarkable increase in the electromechanical coupling, together with an essential decrease in the vertical displacement U3, at the ZnO surface, have been theoretically demonstrated and experimentally verified for definite combinations of the films/plate thicknesses. This property of the structure is attractive for applications to microwave liquid sensors.
Kotel'nikov Institute of Radio Engineering & Electronics, Russian Academy of Sciences (IRE-RAS), Mokhovay Str., 11/7, 125009 Moscow, Russia; Institute for Photonics and Nanotechnologies, Italian National Research Council (IFN-CNR), via Cineto Romano, 42, I-00156 Roma, Italy. Electronic address: enrico.verona@ifn.cnr.it.
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Verona
Kotel'nikov Institute of Radio Engineering & Electronics, Russian Academy of Sciences (IRE-RAS), Mokhovay Str., 11/7, 125009 Moscow, Russia.
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Anisimkin
Acoustoelectronics & Piezoceramic Elpa Corporation, Panfilovsky Prospect, 10, 124460 Zelenograd, Moscow, Russia.
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Osipenko
Acoustoelectronics & Piezoceramic Elpa Corporation, Panfilovsky Prospect, 10, 124460 Zelenograd, Moscow, Russia.
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Voronova
Lamb waves; QL modes; SAW; Si plate; ZnO films