Effects of Oxygen Vacancy Diffusion on Leakage Characteristics of Pt/(Ba_0.5Sr_0.5)TiO₃/Pt Capacitor

Abstract

We investigated leakage characteristics of Pt/(Ba 0.5 Sr 0.5 )TiO 3 (BST)/Pt capacitors by measuring current-voltage characteristics during annealing in vacuum and atmosphere. Built-in electric fields ( E i ) generated at Pt/BST interfaces are derived from analysis of the leakage currents based on the Schottky conduction mechanism. It was found that E i varies in proportion to the square root of annealing time (√ t ). In addition, we found that an external electric field applied during annealing in vacuum induces asymmetric degradation in the leakage characteristics at the top and bottom Pt/BST interfaces. Such behavior in the leakage characteristics is interpreted in terms of the diffusion of oxygen vacancies at the interfaces. Diffusivity of oxygen vacancies is determined from E i -√ t curves.