Epitaxial piezoelectric thin films on flexible substrates

It is well known that the piezoelectric properties of a thin film can be influenced by crystallographic texture. At the extreme case, epitaxial thin films can be deposited on single crystal substrates (with appropriate lattice matching) to effectively achieve a single crystal thin film. Here, the maximum advantage of orientation dependence is found. Typically this has required small, expensive single crystalline substrates. In the past 10 years however, the technique of Ion Beam Assisted Deposition (IBAD) has been developed for applying a biaxial textured template to an arbitrary smooth surface. That is, biaxially textured MgO (~10 nm thick) can be deposited on a flexible, polycrystalline or amorphous substrate. This has opened up a new realm of materials integration possibilities, with the prime example being high-temperature superconducting wires. Here, the same template is utilized for deposition of epitaxial piezoelectric thin films onto flexible substrates.