CHARACTERIZATION OF DOPED BST THIN-FILMS PREPARED BY A MODIFIED SOL-GEL METHOD

Barium strontium titanate (BST) films have been fabricated using a mod ified sol gel method. The crystallization temperature was 100 degrees C higher than that for lead zirconate titanate. The electrical propert ies improved when multiple rapid thermal processing was used. The diel ectric constant of BST films was of the order of 250 which was charact eristic of a small grain size and the presence of a low dielectric con stant barrier. Doping by La, Nb, Mg, Y, Ru, Mn and Gd had an adverse e ffect on the dielectric constant even for small concentrations of abou t 1 at. %. Doping with cerium up to 3 at. % increased the dielectric c onstant of BST films up to 300 while dielectric losses remained low ap proximate to 0.025. The leakage current densities improved for donor t ype doping and were < 10 nA/cm(2) at E=60 kV/cm. BST films 1900 Angstr om thick doped with 3 at. % of Ce had a charge storage density and cap acitance density of 50 fC/mu m(2) and 15 fF/mu m(2) respectively.