Improved Reflectivity and Velocity Model for Aluminum Gratings on YZ LiNbO3

    Authors

    N. Saldanha;D. C. Malocha

    Comments

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    Abbreviated Journal Title

    IEEE Trans. Ultrason. Ferroelectr. Freq. Control

    Keywords

    SURFACE ACOUSTIC-WAVES; SAW; ARRAYS; ENERGY; Acoustics; Engineering, Electrical & Electronic

    Abstract

    Lithium niobate has recently been used for SAW tags and temperature sensors because of its high coupling coefficient and high reflectivity. To increase the device operating frequency for a given electrode line resolution, harmonic operation of the reflector is a very attractive option. When used in conjunction with harmonically operated transducers, the device operating frequency can be increased for a given photolithographic line width resolution. To design and accurately predict the behavior of these devices, it is necessary to model the electrode reflectivity and velocity for both fundamental and second-harmonic operation. The coupling of modes (COM) model has been used to model these devices, however the COM model uses empirically determined coefficients to model reflectivity. In this paper, the reflectivity and velocity of aluminum electrodes is extracted experimentally for fundamental and second-harmonic operation versus metalization ratios ranging from 0.2 to 0.9 and versus normalized metal thickness ranging from 0.4% to 4%. A least-squares fit is then performed on the data using physical terms in the transmission line model to yield equations that can be used in the COM model to predict device behavior over varying metallization ratios and normalized metal thicknesses. Orthogonal frequency-coded (OFC) SAW tags were designed and fabricated and experimentally obtained data are compared with the COM modeled responses for the tags at fundamental and second-harmonic operation to verify the predictions.

    Journal Title

    Ieee Transactions on Ultrasonics Ferroelectrics and Frequency Control

    Volume

    58

    Issue/Number

    4

    Publication Date

    1-1-2011

    Document Type

    Article

    Language

    English

    First Page

    798

    Last Page

    807

    WOS Identifier

    WOS:000289834500014

    ISSN

    0885-3010

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