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

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 degrees Y-cut X-propagating LiTaO3 (36 degrees YX-LT)/AT-cut 90 degrees X-propagating quartz (AT90 degrees X-quartz) and 27 degrees YX-LiNbO3/AT90 degrees 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/lambda = 0.05 (lambda: wavelength) and 0.1, respectively. The fractional bandwidths for 36 degrees YX-LT/AT90 degrees X-quartz and 27 degrees YX-LN/AT90 degrees 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 degrees YX-LT/AT0 degrees 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.

Automated summary

This study investigates the enhancement of high-order surface acoustic wave harmonics by increasing the metallization ratio in bonded dissimilar-material structures. The simulation and experimental results show improvements in fractional bandwidths for different material combinations, and the measured results demonstrate the impact on resonance properties and temperature coefficient of frequency for leaky surface acoustic waves resonators.