E. Gavignet

Theoretical analysis of surface transverse waves propagating on a piezoelectric substrate under shallow groove or thin metal strip gratings

Theoretical calculations are developed in the present study in order to predict propagation characteristics of surface transverse waves (STW) on piezoelectric substrates. A general model has been implemented for both cases of shallow groove or thin metal strip grating resonators. The analysis gives access to the principal STW characteristics (propagation and attenuation coefficients, velocity, electrical and mechanical amplitudes) and the dispersion curve relating the angular frequency to the propagation coefficient. The results obtained are in good agreement with previous results without piezoelectricity. Improvements on theoretical predictions are emphasized for the case of STW propagating under thin metal strips on AT‐cut quartz.

TEMPERATURE DERIVATIVES OF THE FUNDAMENTAL ELASTIC CONSTANTS OF ISOTROPIC MATERIALS

The calculation of the first temperature derivatives of the fundamental elastic constants proposed by Sinha and Tiersten [J. Appl. Phys. 50, 2732 (1979)] for quartz is applied to isotropic materials. Numerical applications are provided for metals used in acoustic wave devices and which may affect the thermal properties of the latter.

Design and test of 3 GHz, fundamental mode surface transverse wave resonators on quartz

Surface transverse wave (STW) resonators, based on the propagation of high velocity shear horizontal waves on Y-rotated quartz were designed, fabricated and tested. A model is presented to predict the resonant frequency of a 3-grating structure as a function of design parameters such as periodicities, metal thickness, and finger-to-gap ratio. Experimental devices have been fabricated by direct e-beam lithography with linewidth geometries in the range of 0.3-0.5 /spl mu/m, and an operating frequency close to 3 GHz in fundamental mode. Two different designs using either a quasi synchronous structure (type 1) or a change of periodicity inside the cavity (type 2) were tested. The best experimental factor of merit is close to the best results already published for quartz STW resonators.

Analysis and experimental study of surface transverse wave resonators on quartz

Since surface transverse wave resonators are becoming increasingly used in high‐frequency electrical component applications, there is a pressing need for reliable simulation tools in this field. We develop analytical techniques for prediction of the resonant peaks of practical devices and apply them to the results of experiments in this laboratory and in others. The devices investigated are three‐grating structures composed of three arrays of metal strips or grooves on quartz substrates, which support a shear horizontal surface wave polarization. The outer gratings act as mirrors for the cavity resonance. The influence of the main design parameters on the resonator response is studied.

A perturbation method for modeling the thermal sensitivity of surface transverse waves

A perturbation approach has been developed to predict the sensitivity of surface transverse waves (STW) to quasi-static temperature effects. This approach is based on the combination of unperturbed STW characteristics and thermoelastic properties of the substrate. The unperturbed STW parameters are calculated taking piezoelectricity into account. Both cases of STW propagating under shallow groove or thin metal strip gratings are studied. An analytical expression of the first order temperature coefficient is obtained in the case of grooves. A simplified calculation is proposed for thin metal strip grating devices. Results are compared to available experimental data. Possible improvements of this model are finally discussed.

Transverse waves trapped by metallic gratings deposited on thin quartz plates

Abstract A theoretical model has been developed to predict the properties of transverse waves propagating under periodic metal strip gratings deposited on piezoelectric plates of finite thickness. The reliability of the model is demonstrated by comparing theoretical and experimental resonance frequencies of synchronous devices built on 128 μm thick AT-and Z-cut plates of quartz. Temperature sensitivities have also been measured experimentally. Finally, a theoretical analysis of the gravimetric sensitivity of these devices is reported. The case of a purely elastic load has been considered. Results are compared to state-of-the-art.