Achieving both high electromechanical response and stable temperature behavior in Si/SiO2/Al/LiTaO3 sandwich structure

摘要

In order to realize the following two goals including high electromechanical coupling coefficient (Ksup2/sup) and zero temperature coefficient of frequency (TCF) in a surface acoustic wave (SAW) device, the propagation characteristics of shear-horizontal type (SH-type) boundary waves in the Si/SiOsub2/sub/Al/LiTaOsub3/sub “sandwich” structure are investigated by the three dimensional (3D) finite element method (FEM). The influences of layer SiOsub2/sub with different thickness (h) on the SH-type boundary waves characteristics, including the phase velocity (vsubp/sub), reflection coefficient (ksubp/sub), Ksup2/sup and TCF, are theoretically analyzed. The results present that the SH-type boundary wave has a maximum Ksup2/sup of 4.45% at h/λ=0.62 and has a zero TCF by adjusting h/λ to 0.69. Owing to the acoustic energy distribution approaching to the SiOsub2/sub/LiTaOsub3/sub boundary, the size of Love wave based devices can be reduced to a few wavelength thickness of Si and 36°YX- LiTaOsub3/sub crystals, and which also give an opportunity to be integrated onto one chip with subsequent electronic circuits.