Phase formation and ferroelectric characteristics of nonfatigue barium bismuth tantalate thin films
Journal
Journal of Applied Physics
Journal Volume
86
Journal Issue
11
Pages
6335-6341
Date Issued
1999
Author(s)
Wen C.-Y.
Abstract
The phase formation and ferroelectric properties of new nonfatigue BaBi2Ta2O9 thin films prepared by the metal-organic decomposition method on Pt/Ti/SiO2/Si substrates have been investigated. After annealing at 700¢XC, BaBi2Ta2O9 films become fully crystallized. On further higher temperatures, an unknown phase is formed by the interaction between the coated films and titanium species diffusing outward from the underlying substrates. A series equivalent-circuit model is successfully applied to analyze the dielectric properties of the unknown phase and BaBi2Ta2O9 films. The intrinsic dielectric constant of BaBi2Ta2O9 thin films is calculated to be 198. In the polarization-electric analysis, BaBi2Ta2O9 thin films exhibit saturated polarization hysteresis curves, which demonstrates their ferroelectric characteristics. The remnant polarization of BaBi2Ta2O9 thin films increases with increasing annealing temperatures. Adding excess amount of bismuth contents (10 mol%) in BaBi2Ta2O9 thin films substantially further improves their ferroelectric properties. However, adding bismuth species more than 10 mol% leads to the formation of Bi2O3, thereby inducing high leakage current. Adding 10 mol% excess bismuth in BaBi2Ta2O9 thin films, the resultant films exhibit a high remnant polarization (2Pr = 14 £gC/cm2), a low coercive field (2Ec = 45 kV/cm), and a fatigue-free characteristic up to 109 switching cycles. ? 1999 American Institute of Physics.
Type
journal article