Structural and electrical characterization of epitaxial, large area ferroelectric films of Ba2Bi4Ti5O18 grown by pulsed excimer laser ablation

Abstract

Excimer laser ablation was used to deposit epitaxial thin films of Ba2Bi4Ti5O18 having mostly c-axis oriented grains. The ferroelectric layer was deposited on an epitaxial conducting oxide electrode layer of LaNiO3, the electrode layer in turn being grown on an epitaxial buffer layer stack on single crystalline (100)-oriented silicon wafers of 3 in. diameter. X-ray diffraction measurements indicate a strong c-axis orientation of the ferroelectric layer. Scanning electron microscopy and atomic force microscopy were used to observe the microstructure of the films and these revealed the homogenous quality of the film with good uniformity over the wafers. Well-defined, saturated ferroelectric hysteresis loops were observed in the compound with values of 1.3 and 0.6 μC/cm2 as saturation and remnant polarization values, respectively, and a coercive field of 47 kV/cm. The results of I–V measurements and complex impedance spectroscopy measurements are presented and a defect formula is proposed for the compound.