Novel Method for Characterization of Ultra-Thin Film Materials Using Surface Acoustic Wave Devices

This paper presents a novel method for the extraction and separation of the acoustoelectric and acoustoelastic losses in nanoscale films by using amplitude and velocity dispersion measurements of SAW devices. The SAW acoustoelectric and acoustoelastic dispersion relations are combined to create the theoretical basis for this technique. This capability is particularly helpful in the characterization of nanoscale films for the purposes of environmental, gas, chemical, or biological sensing, film growth and calibration, and process development. This method is a useful tool in evaluating the parameters of delicate, high-resistance films without contact from potentially damaging probes or exposure to high electric fields. As such, an ultra-thin 1nm thick palladium (Pd) film was chosen for analysis because of its use as a hydrogen-gas sensing element.