Enhancement of leaky surface acoustic wave harmonics excitation using bonded dissimilar-material structures

Abstract

The enhancement of high-order surface acoustic wave (SAW) harmonics by increasing the metallization ratio was theoretically and experimentally investigated in high-performance bonded dissimilar-material structures. The simulation using a finite element method for 36°Y-cut X-propagating LiTaO3 (36°YX-LT)/AT-cut 90°X-propagating quartz (AT90°X-quartz) and 27°YX-LiNbO3/AT90°X-quartz was performed by setting the metallization ratio of the interdigital transducer to a/p = 0.8 (a: electrode width, p: pitch), and the LT and LN thin-plate thicknesses to h/λ = 0.05 (λ: wavelength) and 0.1, respectively. The fractional bandwidths for 36°YX-LT/AT90°X-quartz and 27°YX-LN/AT90°X-quartz were obtained to be 1.6% and 4.0%, respectively, which were larger than those for single LT and LN. For a leaky SAW (LSAW) resonator with a/p = 0.8 fabricated on 36°YX-LT/AT0°X-quartz, the resonance properties and temperature coefficient of frequency of LSAW fundamental waves and harmonics were measured. The measured fractional bandwidth increased from 0.8% to 1.4% for single LT.

High-performance surface acoustic wave devices using composite substrate structures

“…Moreover, the excitation of third harmonics can be enhanced and resonance properties similar to those of the fundamental wave on a single LT or LN substrate can be obtained at a frequency three times higher than that of the fundamental wave by utilizing bonded structures comprising a quartz substrate and an LT or LN thin plate. 92) The structures can also be applied to acoustooptic 93) and sensor devices. In the future, substrate structures that further increase the performance of SAW devices will be investigated.…”

Enhancement of coupling factor in 0th to 4th mode Rayleigh surface acoustic waves on polarity inverted multilayered ScAlN film/AlN and BN substrates

“…A perfect matching layer (PML) was provided at the bottom of the substrate. 35,36) The mechanical loss Q m and dielectric loss were not taken into consideration. The ScAlN film thickness was set to the film thickness at which K 2 was maximized in the theoretical analysis shown in Table I.…”

Analysis of longitudinal leaky surface acoustic waves on bonded structures consisting of similar and dissimilar materials

“…Recently, to satisfy such requirements, high-performance dissimilar-material bonded structures have been proposed. 4,8,[14][15][16][17][18][19][20][21][22] For example, spurious-free, steep attenuation, and good TCF have been reported in heteroacoustic layer (HAL) SAW resonators with 25°YX-LT bonded to a 42°45′Y90°X-Qz support substrate. 14) Furthermore, it is theoretically shown that in the ScAlN/Qz structure, high Q and high coupling can be obtained on an LSAW by using appropriate film thicknesses and Euler angles.…”