Shear-horizontal-type surface acoustic waves on quartz with Ta/sub 2/O/sub 5/ thin film

Abstract

In this paper, the propagation characteristics of two modes of surface acoustic waves (SAWs) on ST quartz with a tantalum pentoxide (Ta/sub 2/O/sub 5/) thin film are investigated theoretically and experimentally. One is the pure shear-horizontal (SH) wave and the another is the Love-wave-type SAW converted from the leaky SAW (LSAW). For these SAWs, stronger energy trapping effects on the surface can be expected by loading the substrate with the TA/sub 2/O/sub 5/ thin film, because this film has a relatively high density. In fact, the film thickness of the Ta/sub 2/O/sub 5/ film required to obtain the minimum insertion loss and the maximum K/sup 2/ for the SH wave on ST-90/spl deg/X quartz is around 0.01 /spl lambda/, which is approximately one-fourth of that reported for silicon dioxide film. Furthermore, the attenuation of the LSAW on ST quartz was reduced by loading with the Ta/sub 2/O/sub 5/ film because the LSAW becomes the Love-wave-type SAW without attenuation.