Structural and Electrical Properties of Ba0.5Sr0.5TiO3 Films on Ir and IrO2 Electrodes

Authors:
  • HCHag-Ju Cho
    Hag-Ju Cho
  • CKChang Seok Kang
    Chang Seok Kang
  • CHCheol Seong Hwang
    Cheol Seong Hwang
  • JKJin-Won Kim
    Jin-Won Kim
  • HHHideki Horii
    Hideki Horii
  • BLByoung Taek Lee
    Byoung Taek Lee
  • SLSang In Lee
    Sang In Lee
  • MLMoon Yong Lee
    Moon Yong Lee
Publisher website
Google Scholar
Abstract
High-dielectric Ba0.5Sr0.5TiO3 (BST) thin films are grown on Ir and IrO2 electrodes by a rf sputtering method. The structural and electrical properties of BST films are investigated. After postannealing at 750° C for 30 min in N2 atmosphere, the interface between BST and IrO2 remains flat and the IrO2 does not show any structural change. On the other hand, a thin IrO2 layer is formed at the interface between the BST and Ir after the same post-annealing. A larger grain size of BST film is obtained on the Ir electrode compared to that of BST film on the IrO2 electrode. Dielectric constants of 36-nm-thick BST films on Ir and IrO2 are 338 and 290, respectively. The leakage current densities of both the Pt/BST/Ir and Pt/BST/IrO2 capacitors are about 20 nA/cm2 at ±1.5 V, which is sufficiently small for application to dynamic random access memory devices.