Structure and Morphology of Epitaxially Intergrown (100)- and (116)-Oriented SrBi_2Ta_2O_9 Ferroelectric Thin Films on SrLaGaO_4(110) Substrates

摘要

SrBi_2Ta_2O_9 (SBT) epitaxial thin films having a mix of (100) and (116) orientations have been grown on SrLaGaO_4(110) by pulsed laser deposition. X-ray diffraction θ-2θ and pole figure scans, and cross-sectional transmission electron microscopy (TEM) analyses revealed the presence of two epitaxial orientations, SBT(100)‖SLG(110); SBT[001]‖SLG[001] and SBT(116)‖SLG(110); SBT[(1-bar)10]‖SLG[001]. By calculating the integrated intensity of certain x-ray diffraction peaks, it was established that the crystallinity and the in-plane orientation of the (100) and (116) orientation are best at a substrate temperature of 775 °C and 788 °C, respectively, and that the volume fraction of the (100) orientation at about 770 °C reached about 60%. By scanning force microscopy and cross-sectional TEM investigations we found that the a-axis-oriented grains are rounded and protrude out due to the rapid growth along the [110] direction, leading to a distinct difference of the surface morphology between (100)- and (116)-oriented grains.