Sol-gel processing and properties of cerium doped barium strontium titanate thin films

A stock solution sol-gel based method for making Barium Strontium Titanate (BST) thin films has been developed. A modified titanium alkoxide was combined with a barium and/or strontium inorganic salt in methoxyethanol and ethylene glycol to form the solution. The effect of chemistry on the stability of this BST solution is discussed. The crystallization temperature of 700-725 degrees C for rapid thermally processed films dropped by 100 degrees C using cerium doping. The permittivity for undoped films was approximate to 250 and doping by 3 at.% Ce increased the dielectric constant by 20%. A remanent polarization of approximately 0.5 mu C/cm(2) and coercive field of 28 kV/cm were measured for the undoped films. The leakage current densities were <10 nA/cm(2) at E = 60 kV/cm and improved for cerium concentrations up to 3 at.%. The charge storage density was approximate to 50 fF/mu m(2) at 200 kV/cm and the DC breakdown voltage was 300 kV/cm for Ce doped films.