Abstract
The dielectric properties of dual-layer PZT/ZrO2 thin films were measured at microwave frequencies in both a metal–insulator–metal (MIM) capacitor and a coplanar waveguide (CPW) up to 50 GHz. Both PZT and ZrO2 films were prepared by the chemical solution deposition method. The measured dielectric loss of the PZT/ZrO2 film was approximately 0.08 at 30 GHz, much lower than that of typical PZT thin films. The dielectric constants obtained using the MIM capacitor with 360 nm PZT/65 nm ZrO2 and using the CPW with 420 nm PZT/280 nm ZrO2 were 47 and 130, respectively, at 50 GHz. Capacitance tunability was ~30% at +25 V and up to 50 GHz. The measured values obtained indicate that PZT/ZrO2 thin films may be suitable for the use of dielectric layers in tunable RF devices and RF MEMS capacitive switches operating at millimetre wave frequencies.
