(中南大學(xué) 粉末冶金國家重點(diǎn)實(shí)驗(yàn)室，長沙 410083)
摘 要: 采用溶膠-凝膠法在Si和Pt/Ti/SiO2/Si襯底上制備鈣鈦礦結(jié)構(gòu)的Ba0.8Sr0.2TiO3(BST)薄膜。對其前驅(qū)體干凝膠進(jìn)行熱重與差熱(TG-DSC)分析，以此確定薄膜的熱處理工藝。分別采用X射線衍射(XRD)、掃描電子顯微鏡(SEM)、原子力顯微鏡(AFM)和B1500A半導(dǎo)體器件分析儀對薄膜性能進(jìn)行表征。結(jié)果表明：800 ℃下在氧氣氣氛中退火15 min可以得到結(jié)晶度良好、致密度較高的純鈣鈦礦相BST薄膜，其對應(yīng)的晶粒尺寸和均方根粗糙度分別為30~40 nm和5.80 nm。薄膜厚度為160~378 nm時，BST薄膜的介電常數(shù)和介質(zhì)損耗隨薄膜厚度的增加而增大。厚度為300 nm的BST薄膜的介電常數(shù)由于尺寸效應(yīng)隨溫度升高單調(diào)降低，且居里溫度在室溫以下。
關(guān)鍵字: Ba0.8Sr0.2TiO3(BST)薄膜；溶膠-凝膠法；介電性質(zhì)
（State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract: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.
Key words: Ba0.8Sr0.2TiO3 (BST) thin films; sol-gel method; dielectric property
