Electrical Performances of a Surface Acoustic Wave Device With Inter-Digital Transducers Electrodes in Local Resonances

Abstract

In this paper, we investigate numerically the coupling of the Rayleigh mode with the micro-wall resonance modes in inter-digital transducers (IDTs) electrodes of surface acoustic wave (SAW) devices. We perform a finite element analysis (FEA) of the SAW features using an implemented model using COMSOL Multiphysics® software. The SAW structure comprises identical transmitter and receiver IDTs electrodes, with different electrode heights (he). The proposed FEA study is based on the extraction of reflection (S11) and transmission (S21) coefficients of the SAW device. The IDTs are considered to be a micro-wall phononic crystal acting as local resonators at frequencies inside the SAW passband. The locally resonance gap is strongly dependent on the he value, S11 and S21 parameters are affected by the SAW energy absorption in the IDTs system. We have chosen two he values (0.5 and 3 µm) to study low and high aspect ratios of micro-walls; corresponding respectively to Bragg-type and resonance-type bandgaps appearing near to the SAW central frequency. At the SAW resonance frequency, the return (S11) and the insertion (S21) losses are reduced. S21 is reduced by 12.73 and 18.49 dB for he=0.5 and 3 µm, respectively, accompanied by an increase in the quality factor, and S11 parameter is reduced by 1.357 and 4.98 dB for he=0.5 and 3 µm, respectively.

Electro-Acoustic Properties of Scandium-Doped Aluminum Nitride (ScxAl1-xN) Material and its Application to Phononic Crystal-Coupled SAW Devices

“…In other words, the propagation of the SAW is disturbed by the presence of the ridged structure, resulting in a decrease in the mechanical energy of the IDT receiver. S 21 also presents a slight frequency shift toward low frequencies because of the mass loading effect caused by the presence of the PnC [87,88]. S 21 in the delay line also shows small oscillations, which are induced by Fabry-Perot reflection from the metallic IDT fingers [89].…”

Process and Device Simulation of SAW Temperature Sensors Compatible with 1 µm CMOS Technology

“…During acoustic wave propagation over the piezo substrate, its velocity changes while the surrounding environment conditions change, the modified acoustic wave is transduced back into an electromagnetic signal that is transmitted for processing (determination of frequency shift or time delay according to the sensor type). The propagation properties (like wavelength and resonance frequency) of acoustic waves in piezoelectric media depend on the substrate material, the crystal cut and the structure of electrodes [5,6].…”