Effects of vanadium doping on structure and electrical properties of SrBi 4Ti 4O 15 thin films

Abstract

The effects of vanadium(V) doping into SrBi 4Ti 4O 15 (SBTi) thin films on the structure, ferroelectric, leakage current, dielectric, and fatigue properties have been studied. X-ray diffraction result showed that the crystal structure of the SBTi thin films with and without vanadium is the same. Enhanced ferroelectricity was observed in the V-doped SrBi 4Ti 4O 15 (SrBi 4− x/3 Ti 4− x V x O 15, SBTiV- x ( x = 0.03, 0.06, and 0.09)) thin films compared to the pure SrBi 4Ti 4O 15 thin film. The values of remnant polarization (2 P r ) and coercive field (2 E c ) of the SBTiV-0.09 thin film capacitor were 40.9 μC/cm 2 and 105.6 kV/cm at an applied electric field of 187.5 kV/cm, respectively. The 2 P r value is over five times larger than that of the pure SBTi thin film capacitor. At 100 kHz, the values of dielectric constant and dielectric loss were 449 and 0.04, and 214 and 0.06 for the SBTiV-0.09 and the pure SBTi thin film capacitors, respectively. The leakage current density of the SBTiV-0.09 thin film capacitor measured at 100 kV/cm was 6.8 × 10 −9 A/cm 2, which is more than two and a half orders of magnitude lower than that of the pure SBTi thin film capacitor. Furthermore, the SBTiV-0.09 thin film exhibited good fatigue endurance up to 10 10 switching cycles. The improved electrical properties may be related to the reduction of internal defects such as bismuth and oxygen vacancies with changes in the grain size by doping of vanadium into SBTi.