Determining the elastic properties of thin films and their changes by means of surface acoustic waves (SAWs)

A method is proposed for determining by means of SAWs the density and elastic moduli and their changes during the adsorption of gas molecules by a film. The method is based on a comparison of the experimentally measured and analytically calculated values of the group velocity and relative changes in the phase velocity of the wave for layered structures with the given film and substrates of various materials. The method has been tested using hydrogen sensitive palladium films. A comparison has been made of the elastic properties of palladium in the form of a thin film, a bulk polycrystal and a single crystal.