CeO2缓冲层对蓝宝石基Ba0.6Sr0.4TiO3薄膜结构和介电性能的影响

摘要

Pt/BST/Al2O3 and Pt/BST/CeO2/A12O3 interdigital capacitors were fabricated on the A12O3 (1102) substrates,in which CeO2 buffer layer and Ba0.6Sr0.4TiO3 (BST) film were prepared by magnetron sputtering and pulsed laser deposition,respectively.Impacts of CeO2 buffer layer on structure,surface morphology and dielectric properties of the deposited BST thin film were investigated using X-ray diffiraction system,atomic force microscope and LCR meter,respectively.It is found that BST film grown on Al2O3 (1102) substrates without the CeO2 buffer layer is polycrystalline,however,the one with buffer layer is epitaxial.Compared with the polycrystalline BST film without the CeO2 buffer layer,the grain size and root mean square roughness of BST film grown on CeO2 are relatively smaller.At a bias voltage of 40 V,the tunability and the minimum dielectric loss are 13.2％ and 0.021 for Pt/BST/Al2O3 capacitor and 25.8％ and 0.014 for Pt/BST/CeO2/A12O3 capacitor.These results indicate that CeO2 buffer layer has a great impact on the structure and dielectric properties of BST film grown on the Al2O3 substrate.%利用磁控溅射法制备CeO2缓冲层,通过脉冲激光沉积法制备Ba0.6Sr0.4TiO3(BST)薄膜,在A12O3(1102)蓝宝石基片上构架了Pt/BST/CeO2/A12O3和Pt/BST/A12O3叉指电容器,对比研究了CeO2缓冲层对BST薄膜结构和叉指电容器介电性能的影响.通过X射线衍射仪、原子力显微镜和LCR表分别对叉指电容器的结构、表面形貌和介电性能进行了表征.实验发现,直接沉积在蓝宝石上的BST薄膜为多晶结构,生长在CeO2缓冲层上的BST为(001)取向的高质量外延薄膜.生长在CeO2缓冲层上的BST薄膜相对于没有缓冲层的BST薄膜具有更小的晶粒和均方根粗糙度.在40 V偏置电压下,Pt/BST/A12O3和Pt/BST/CeO2/A12O3叉指电容器的调谐率分别是13.2％和25.8％;最小介电损耗为0.021和0.014.结果表明CeO2缓冲层对生长在蓝宝石基片上的BST薄膜结构和介电性能具有重要影响.