The effects of baking cycles on the properties of ferroelectric thin films

Sol gel methods are the most popular and successful means of producing ferroelectric thin films of compounds such as Pb(Ti,Zr)O3 and SrBi2Ta2O9. The heat treatment temperatures used to form the crystalline films are characterised by a low-temperature pyrolysis step, generally below 400°C followed by crystallisation and annealing between 600°C and 800°C. In this paper the effects of baking on the thin gel film will be presented and discussed.The method chosen to evaporate the solvent and eliminate organic ligands influences the morphology, chemistry and electrical properties of thin films profoundly. The atmosphere and heating rate, particularly, have been found to change the oxidation state of the metallic species in the film. A mechanism that explains the formation of Bi2O3 and PbO layers on the surface and the commonly observed depletion of these oxides in ferroelectric thin films is given.