Low-loss, tunable bismuth zinc niobate films deposited by rf magnetron sputtering

Abstract

Near-stoichiometric Bi1.5Zn1.0Nb1.5O7 (BZN) films were deposited by rf magnetron sputtering. The relative permittivity and dielectric loss of BZN films were measured with frequencies up to 100 MHz using planar Al2O3/Pt/BZN/Pt and Si/SiO2/Pt/BZN/Pt capacitor structures. BZN films with thicknesses in the range of 160 to 170 nm exhibited electric field tunable permittivities up to 220, and dielectric loss tangents less than 0.0005. A maximum applied bias field of 2.4 MV/cm resulted in a ∼55% tunability of the dielectric constant. The permittivity was independent of the measurement frequency over a wide frequency range (10 kHz–100 MHz). Above 1 MHz, losses were increasingly dominated by conductor losses of the Pt bottom electrode. Their excellent dielectric properties make BZN films attractive candidates for low-loss, medium-permittivity integrated device applications.