Halogen-Light-Enhanced Metallorganic Decomposition of SrBi[sub 2]Ta[sub 2]O[sub 9] Ferroelectric Thin Films

Abstract

We investigated the influence of the halogen-light exposure on the metallorganic decomposition of strontium bismuth tantalate [SrBi 2 Ta 2 O 9 (SBT)] thin films deposited by chemical-solution deposition (CSD) on platinum (Pt) capacitors. The UV absorption spectrum obtained using Fourier transform infrared showed that the removal of the residual organic species from the SBT solution layer was enhanced by the halogen light during drying at 150°C. The halogen-light exposure improved ferroelectric properties and the formation of a (200)-preferred film structure, a superior ferroelectric property. In addition, the decomposition of oxidated bismuth (Bi-O bonds) in SBT as a result of the halogen-light exposure was also observed. Some reduction in metallic Bi from the oxidated state that occurred during the high temperature rapid thermal annealing was enhanced by the halogen-light exposure. The high Bi: Bi 2 O 3 ratio in the SBT film samples exposed to the halogen light was responsible for their high leakage current. At 400°C, the annealing in a N 2 O ambient was effective in oxidizing Bi and in reducing the leakage current densities by about 2 orders of magnitude. Although the specific interaction between the halogen light and the CSD film remains unclear, the cost-effective and safe halogen lamp may be an appropriate choice for photoassisted thermal processes for the production of ferroelectrics. © 2010 The Electrochemical Society.