On the possibility of direct determination of elastic constants of thin films in the transverse direction to the film plane

Abstract

The possibility of determining the elastic constants of thin films deposited on the free end of an acoustic line in the transverse direction to the film plane is discussed. The proposed technique is based on measurement of changes in eigenfrequencies of a composite acoustic resonator composed of an acoustic line and an electroacoustic transducer of bulk acoustic waves upon its loading with a thin-film coating. Results of experimental verification of the proposed technique for a thin (3.25 μm) film of DST-30 rubber deposited on the free end of a resonator made of fused quartz with an operating range of 80–150 MHz are described. It is shown that the elasticity of a divinyl styrene rubber film lengthwise and crosswise its plane differs by almost four orders of magnitude.