High-frequency surface acoustic wave device based on thin-film piezoelectric interdigital transducers

Using high-quality epitaxial c -axis Pb ( Zr 0.2 Ti 0.8 ) O 3 films grown by off-axis magnetron sputtering onto metallic (001) Nb -doped SrTiO 3 substrates, a nonconventional thin-film surface acoustic wave device based on periodic piezoelectric transducers was realized. The piezoelectric transducers consist of a series of ferroelectric domains with alternating polarization states. The artificial modification of the ferroelectric domain structure is performed by using an atomic force microscope tip as a source of electric field, allowing local switching of the polarization. Devices with 1.2 and 0.8 μ m wavelength, defined by the modulation period of the polarization, and corresponding to central frequencies in the range 1.50 - 3.50 GHz have been realized and tested.