Preparation of bi-based ferroelectric thin films by sol-gel method

Abstract

The effects of Bi/Ta and Sr/Ta mole ratios on ferroelectric properties of SrxiyTa2Oz [ SBIT(x/y/2.0); 0.7蠄x蠄1.0, 2.0蠄y蠄2.6] thin-film capacitors were investigated. The SBITfilms were grown by the sol-gel method using a spin-on coating on Pt/Ta/SiO2/Si andPt/Ti/SiO2/Si substrates. The films were annealed at 800Ŷ C for one hour in oxygen atmosphere. Remanent polarization (Pr) depended strongly on the Sr/Ta mole ratio, and increased with decrease of the Sr/Ta mole ratio. On the other hand, Pr was almost independent of the Bi/Ta mole ratio. Scanning electron microscopy (SEM) images show that crystal grains grew with decrease of the Sr/Ta mole ratio. Electron probe micro analyzer (EPMA) analysis revealed that Bi content in SBIT films increased withdecrease in Sr composition from stoichiometry. © 1995 The Japan Society of Applied Physics.