High coupling piezoelectric thin films of Pb"Zr,Ti…O3-based ternary perovskite compounds for GHz-range film bulk acoustic resonators

We have deposited nearly stress-free single-crystal thin films of (001) Pb(Mn,Nb)O3–Pb(Zr,Ti)O3 (PMnN-PZT) on (001)MgO substrates by rf-magnetron sputtering using a quenching process after the film growth. It is found that single c-domain/single-crystal thin films of PMnN-PZT containing 5%–10% PMnN show a strong hard ferroelectric response with 2Ec≅400 kV/cm and Ps≅70 μC/cm2. GHz-range film bulk acoustic resonators incorporating PMnN-PZT thin films have been fabricated with microelectromechanical system technology. The maximum electromechanical coupling coefficient kt and mechanical quality factor Qm were 0.7 and 185 in the 4 GHz range, respectively.