Acoustic resonator filters used in wireless communications incorporate a piezoelectric film, often aluminum nitride (AlN), to form an electromechanical resonator. Doping AlN with scandium can increase its piezoelectric response and improve filter performance. However, at high scandium concentrations, defects occur in the films and therefore processing conditions must be optimized. Here, we describe a new atomic force microscope design with interferometric sensing of cantilever displacement that enables quantitative piezoresponse force microscopy. This can assist in optimizing film processing conditions by providing a quantitative measure of piezoelectric response that can be directly correlated with observation of grain structure and film defects.
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