Thin film shear modulus determination with quartz crystal resonators: a review

An important application of quartz crystal resonators is the quartz crystal microbalance (QCM). It is well established as thickness monitor in vacuum deposition units or as chemical sensor, e.g., in an electronic nose or electronic tongue. As QCM the high sensitivity of the mechanical eigenfrequency to surface mass changes is exploited. QCMs obtain their chemical sensitivity and selectivity from a chemically active coating, which interacts with the surrounding environment. Analyte sorption in the sensitive layer results in a change of the surface mass and hence in the resonator's frequency. A new fascinating application is the determination of material properties of thin viscoelastic films. The recently developed methods will be reviewed.