BZN thin film capacitors for microwave low loss tunable applications

Bismuth zinc niobate (BZN), a high dielectric constant material that combines low dielectric losses with an electric-field dependent permittivity, was implemented as the dielectric in metal-insulator-metal (MIM) capacitors. Dielectric properties up to 20 GHz were evaluated by measuring reflection coefficients with a vector network analyzer. The dielectric constant was around 180 and the quality factor remained greater than 100 up to 5 GHz for 64 mu m(2) devices. No onset of dielectric relaxation, as seen in bulk ceramic data, could be detected in the measured frequency range. The results show that BZN thin films have great potential for low loss, tunable microwave devices.