A Full-Wave Analysis of Surface Acoustic Waves Propagating on a SiO2 Overlay/Metal Grating/Rotated $Y$-Cut $X$-Propagating LiNbO3 Substrate Structure

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In this paper, we describe a full-wave analysis of an SiO2 overlay with a finite thickness/metal grating/rotated $Y$-cut $X$-propagating LiNbO3 (YX-LN) substrate structure. The effects of the thickness and surface topology of the SiO2 overlay and the metal grating selection upon the excitation and propagation characteristics of acoustic guided modes are discussed in detail. It is shown that in the structure there propagate three acoustic guided modes. One type of mode concentrates the energy near the metal grating and generates piezoelectric boundary acoustic waves (PBAWs) with a relatively large electromechanical coupling factor when the SiO2 thickness becomes semi-infinite. Another mode concentrates its energy near the top surface of the SiO2 overlay and generates the Rayleigh-type surface acoustic wave (SAW) on SiO2 when the thickness is semi-infinite; with an increase in SiO2 thickness, it rapidly loses its piezoelectric coupling. The remaining mode is a series of guided modes trapped in the SiO2 layer, in which the SiO2 layer behaves as a waveguide because of its low acoustic wave velocities.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2009-07-25