Impact of Yb content on structural properties and ferroelectric characteristics of BiFeO3 thin films on Pt/TiN/Si substrates

This work reports the impact of Yb content on the structural and ferroelectric properties of the BiFeO 3 thin films fabricated on the Pt/TiN/Si substrates by dc and rf cosputtering. The Yb-doped BiFeO 3 thin films were prepared under three different Yb plasma powers (10 W, 11 W, 12 W). X-ray diffraction demonstrated that the Yb-doped BiFeO 3 thin films showed the distortion of rhombohedral structure. Scanning electron microscopy indicated that the Yb-doped BiFeO 3 thin film prepared at the 11 W condition exhibited smaller grain sizes than those of the other conditions. Atomic force microscopy revealed that the Yb-doped BiFeO 3 thin film treated at the 11 W condition featured a lower surface roughness compared with the other conditions. Secondary ion mass spectrometry manifested that the Yb-doped BiFeO 3 film showed the sharp compositional profiles near the BiFeO 3 /Pt interface. Moreover, X-ray photoelectron spectroscopy signified that the Yb-doped BiFeO 3 film fabricated at the 11 W condition possessed a higher Fe 3+ /Fe 2+ concentration ratio and a lower intensity of oxygen vacancies than the other conditions. Among these conditions, the BiFeO 3 thin film fabricated at the 11 W condition exhibited the lowest leakage current of 1.71 × 10 –5 A/cm 2 at an electric field of 200 kV/cm and the highest remnant polarization of 61.7 μC/cm 2 .