The influence of distribution of Na+-dopant on the structure and dielectric properties of Ba0.25Sr0.75TiO3 thin film
杂质分布设计对钛酸锶钡薄膜结构和性能的影响

Na+-doped and compositional graded doped Ba0.25Sr0.75TiO3 thin films were grown on Pt/Ti/SiO2/Si substrates by Sol-Gel technique. The dielectric properties of thin films were investigated as a function of Na+ doping level. It is revealed that with the increase of Na+ concentrations both the dielectric constant and the loss decrease continuously while the leakage current initially decreases (Na+< 2.5mol%) and then increases. The increase of leakage current may be caused by the formation of porous structure which was confirmed by field emission scanning microscopy (FE-SEM). The improvement of overall dielectric properties were achieved by using the compositional graded doping which results in a better microstructure in the film.