Nanoscale Observation of Poling Behaviors in Nd-Substituted Bi_4Ti_3O_(12) Ferroelectric Thin Films

摘要

In this study, the effects of oxygen vacancies on the local poling properties of Bi-layered ferroelectric thin films were examined. Bi_(3.15)Nd_(0.85)Ti_3O_(12) (BNT) thin films were coated on Pt(111 )/Ti/SiO_2/Si substrates using a sol-gel method. An oxygen vacancy of 2.4 ± 0.5% was observed mainly at the Bi_2O_2~(2+) layers in the film that annealed in an oxygen-deficient atmosphere. The film containing oxygen vacancies showed a shift in the polarization-electric field hysteresis loop. Contact-mode electrostatic force microscopy revealed a domain pinning behavior in the BNT film with oxygen vacancies. The unpolarized domains were explained by the built-in field formed by the oxygen vacancies in the Bi_2O_2~(2+) layers.