Microstructure and piezoelectric properties of PZT-based ternary perovskite Pb(Mn,Nb)O3-PZT thin films

Single crystal thin films of the PZT-based ternary perovskite, xPb(Mn,Nb)O₃-(1-x)PZT, were fabricated by a magnetron sputtering on (001)MgO substrates. The sputtered thin films were quenched in air after the deposition. The PZT-based thin films exhibited the hard ferroelectric behavior with high piezoelectric coupling factors k_t, k_t=70%, measured at GHz range FBAR structure. The PZT-based thin films showed a high mechanical quality factor Q_m, Q_m=185. The observed k_t and Q_m are, to our knowledge, the highest in the reported values. The achievement of the high Q_m will be owed to the single crystal-like high density film structure with the doped Mn acceptors and oxygen vacancies achieved by the sputtering deposition followed by the quenching. The figure of merit k² _tQ_m is almost the same to piezoelectric AIN thin films. It is confirmed the quenched PZT-based ternary perovskite thin films have a potential for a fabrication of FBAR and/or wide band filters at GHz range.