富钛梯度(Ba_(0.6)Sr_(0.4))TiO_3薄膜的介电调谐性能研究

The dielectric tunable properties of(Ba_(0.6)Sr_(0.4))TiO_3 grade thin films with rich titanium

采用溶胶凝胶工艺,在Pt/Ti/SiO2/Si衬底制备了富钛(Ba0.6Sr0.4)TiO3(BST)薄膜和富钛梯度薄膜。利用X射线衍射(XRD)和扫描电镜(SEM)分析测定了BST的微结构和薄膜的表面形貌,研究了富钛含量和梯度结构对BST介电调谐性能的影响。结果表明富钛薄膜中析出了TiO2相,薄膜的介电常数、损耗和调谐量随着钙钛矿结构(ABO3)中A/B的增加而增加;当A/B为0.68时,有最小的介电损耗0.017;当A/B为1时,有最高的介电常数和调谐量,分别为592%和43.72%。而富钛梯度薄膜因TiO2的析出而丧失晶格不匹配应力的影响,在介电调谐性能上并没有表现出梯度薄膜的综合优异性能。

The BST thin films and grade BST thin film with rich titanium were fabricated by sol-gel method on Pt/Ti/SiO2/Si substrate. X-ray diffraction and scanning electron microscopy were used to determine the microstructure and the morphology of the BST films. The influence of the rich titanium content and the grade structure on dielectric tunable properties of BST thin films was investigated. It found that the BST thin films with rich titanium precipitate TiO2 and their dielectric constant,dielectric loss and tunability all increase with the increasing the ratio of A and B of perovskite structure （ABO3）. BST thin films showed the smallest dielectric loss of 0. 017 when the ration of A and B was 0.68 and BST thin films exhibited the highest dielectric constant of 592 and the largest tunability of 43.72% when the ration of A and B was 1. The graded BST thin film with rich titanium lost the crystal lattice mismatch stress because of the precipitation of TiOz. It didn＇t show wonderful dielectric tunable properties of graded thin films.