High performance piezoelectric films for high frequency MEMS ultrasonic transducers

(1-x)PbYb1/2Nb1/2]O-3-xPbTiO(3) (MN-PT, x=0.5) thin films were investigated for high frequency transducer applications in this work. Firstly, highly (001) oriented LaNiO3 (LNO) thin films were prepared on Si (001) substrates by a simple metal organic decomposition technique. The room temperature resistivity of the LNO thin films was 0.65 m ohm center dot cm. Then PYbN-PT thin films were deposited onto the LNO/Si substrates by son-gel processing. X-Ray diffraction analysis revealed that the films of PYbN-PT were highly (001) oriented along the LNO/Si substrates. The films had a uniform grain size of about 80-120 rim. At 1 KHz, the dielectric permittivity was 920, and dielectric loss is about 0.035. The ferroelectric films displayed good P-E hysteresis characteristics and better temperature stabilization compared with films that have lower Curie temperature. Finally, following PiezoCAD modeling, the PYbN-PT Rim high frequency transducer was designed.