Epitaxial growth and dielectric characterization of atomically smooth 0.5Ba(Zr _0.2 Ti _0.8 )O ₃ -0.5(Ba _0.7 Ca _0.3 )TiO ₃ thin films

The authors report the epitaxial growth and the dielectric properties of relaxor ferroelectric 0.5Ba(Zr _0.2 Ti _0.8 )O ₃ -0.5(Ba _0.7 Ca _0.3 )TiO ₃ thin films with atomically flat surface on GdScO ₃ single crystal substrates. The authors studied the effects of growth conditions, such as the substrate temperature and the oxygen pressure on the structure of the thin films, as measured by x-ray diffraction, to identify the optimal growth conditions. The authors achieved sustained layer-by-layer growth of 0.5Ba(Zr _0.2 Ti _0.8 )O ₃ -0.5(Ba _0.7 Ca _0.3 )TiO ₃ films as monitored by in situ and real time reflective high energy electron diffraction. Atomic force microscopy investigations showed atomically smooth step terrace structures. Aberration-corrected scanning transmission electron microscopy images show good epitaxial relation of the film and the substrate without any line defects. High dielectric constant (∼1400) and slim hysteresis loops in polarization-electric field characteristics were observed in 0.5Ba(Zr _0.2 Ti _0.8 )O ₃ -0.5(Ba _0.7 Ca _0.3 )TiO ₃ films, which are characteristic of relaxor-type ferroelectric materials.