Ba_(0.8)Sr_(0.2)TiO_3薄膜的溶胶-凝胶法制备及表征

Preparation and characterization of Ba_(0.8)Sr_(0.2)TiO_3 thin film by sol-gel method

采用溶胶-凝胶法在Si和Pt/Ti/SiO2/Si衬底上制备钙钛矿结构的Ba0.8Sr0.2TiO3（BST）薄膜。对其前驱体干凝胶进行热重与差热（TG-DSC）分析，以此确定薄膜的热处理工艺。分别采用X射线衍射（XRD）、扫描电子显微镜（SEM）、原子力显微镜（AFM）和B1500A半导体器件分析仪对薄膜性能进行表征。结果表明：800℃下在氧气气氛中退火15 min可以得到结晶度良好、致密度较高的纯钙钛矿相BST薄膜，其对应的晶粒尺寸和均方根粗糙度分别为30~40 nm和5.80 nm。薄膜厚度为160~378 nm时，BST薄膜的介电常数和介质损耗随薄膜厚度的增加而增大。厚度为300 nm的BST薄膜的介电常数由于尺寸效应随温度升高单调降低，且居里温度在室温以下。

Ba0.8Sr0.2TiO3 （BST） ferroelectric thin films with perovskite structure were prepared on Si and Pt/Ti/SiO2/Si substrates by sol-gel method. The heat-treatment technology （TG-DSC）, X-ray diffraction （XRD）, scanning electron microscope （SEM）, atomic force microscope （AFM） and B1500A semiconductor device analyzer were employed to analyze the phase structure, microstructure and dielectric property of the BST thin films. The results show that BST thin films with good crystallinity and high density are obtained after annealing at 800℃for 15 min under oxygen atmosphere, their average grain size and root mean square roughness （RMS） are 30~40 nm and 5.80 nm, respectively. The dielectric constant and dielectric loss increase with the increase of the thickness of the BST thin films ranging from 160 nm to 378 nm. The dielectric constant of the BST thin film with the thickness of 300 nm decreases with the increase of temperature because of size effect, the Curie temperature is below the room temperature.