Synthesis and dielectric characteristic of Ba1-xSxTiO3 thin films-based strontium-barium alkoxides derivatives

Homogeneous Ba1-xSrxTiO3 (BST) sols have been synthesized using barium, str ontium acetate, and titanium tetra-II-butoxide as starting materials. Aceti c acid and ethylene glycol were selected as solvents. The formamide was sel ected as an additive to adjust the solution viscosity in order to reduce th e crack of the BST thin films. The structure and thermal decomposition proc ess of BST gel powders and thin films, which were prepared from a precursor of strontium-barium titanate alkoxides, were investigated by means of diff erential thermal/thermogravimetric analyses (DTA/TGA) and X-ray diffraction measurements. DTA/TGA technique was used to determine the temperature of d ecomposition and crystallization. The BST thin films were prepared by a spi n-on sol-gel process on Pt/Ti/SiO2/Si (1 0 0) substrates. The thin films we re crystallized above 600 degreesC, and formed completed perovskite structu re around 700 degreesC. The capacitance-voltage curve shows that the polari zation and capacitance vary non-linearly with an applied field due to the d omain structure. A tunability of dielectric constant about 29.3% and a figu re of merit, K = 6.5, were obtained with an electric field of 150 kV cm(-1) . (C) 2001 Elsevier Science B.V. All rights reserved.