Size Effect Of The Non-linear Ferroelectric Thin Films Of Barium Strontium Titanate

In this thesis, the relationships of the dielectric properties with themicrostructures, thicknesses and grain sizes were studied.First, the BST thin films were prepared at the optimized parameters by RFmagnetron sputtering and annealed by two post treatments: RTA andtube-furnace. How the factors, temperature, atmosphere et al., of these postannealed methods influenced the microstructures (crystallization, orientation,roughness degree of surface, and the grain sizes) of BST thin films wasinvestigated. And the effective method of controlling grain sizes of BST thinfilms was got at last.Second, the dielectric properties of BST thin films was measured: thedielectric constant was 746,the loss tangent data was 1.7%.The cures of εr-f,D-f, εr-V were got and the reasons of why these cures were changed asthat manner were given and proved also.At last, based on the upward studies, the differences of the electricproperties of BST thin films which had different thicknesses and grain sizeswere experimented. The results are as follows:①the BST thin films of the samethickness, the larger the grain sizes, the higher the dielectric constant and △εwere;②with the increasing of thicknesses of BST thin films, the dielectricconstant was increased at first and appeared a maximum at 650nm, thendecreased; ③the △εwas also unequal at different thicknesses. Themaximum appeared at the thinnest films (260nm), the minimum at the filmswhich had the highest dielectric constant.