Thin film conductivity sensor based on acoustoelectric interaction in 36° YX lithium tantalate

Abstract

The acoustoelectric interaction of leaky surface acoustic wave (LSAW) on 36° rotated Y-cut X-propagation lithium tantalate was studied and the thin film conductivity sensor was implemented on this base. The technique of slow evaporation of thin copper film on the wave propagation surface with simultaneous measurements of the wave amplitude and phase was used. The observed strong response of the LSAW to the film conductivity is explained by the acoustoelectric attenuation and velocity change. The sheet conductivity extracted from the changes in wave amplitude and phase was compared with the results of DC resistance measurements. The potential of LSAWs in LiTaO3 for contactless monitoring of changes in thin film conductivity has been demonstrated.