(111)取向(Pb,La)TiO3铁电薄膜中90°纳米带状畴与热释电性能的研究

采用射频磁控溅射技术在Pt/Ti/SiO₂/Si(100)衬底上生长了掺镧钛酸铅(PLT)铁电薄膜.用X射线衍射技术(XRD)研究了PLT薄膜结晶性能，结果表明PLT薄膜为 (111)择优取向钙钛矿相织构.使用原子力显微镜(AFM)和压电响应力显微镜(PFM) 分别观察了PLT薄膜的表面形貌和对应区域的电畴结构.PFM观察显示PLT薄膜中存在90°纳米带状畴，电畴的极化为首尾相接的低能量的排列方式，带状畴的宽度为20—60nm.研究了PLT10铁电薄膜的制备条件与性能之间的关系.发现在优化条件下制备的PLT10铁电薄膜的介电常数ε_r为365、介电损耗tgδ为0.02，热释电系数γ为2.18×10^-8C·(cm²·K)^-1，可以满足制备非制冷红外探测器的需要. 关键词： PLT薄膜 电畴 PFM 极化

Study of nanoscale banded 90° domain patterns and pyroelectric properties in (111) oriented (Pb,La)TiO3 thin films

Lanthanum doped lead titanate (PLT) ferroelectric thin films were grown on Pt/Ti/SiO₂/Si(100) substrates using RF magnetron sputtering. X-ray Diffraction (XRD) was applied to study crystalline properties of PLT films, and XRD patterns of PLT thin films show that there appeared (111) preferred-oriented tetragonal perovskite phase. The ferroelectric domain patterns and the corresponding topography of PLT thin films have been investigated using piezoresponse force microscopy (PFM) and atomic force microscopy (AFM), respectively. PFM observations show that there exist nanoscale banded 90° domain patterns 20 to 60 nm in width and low energy head-to-tail polarization configurations in PLT film. The relationship between fabricating conditions and properties of PLT10 thin films was studied. It was found that PLT10 thin film fabricated under the optimized conditions possess dielectric constant ε_r=365, dielectric loss tgδ=0.02, and pyroelectric coefficient γ=2.18×10^-8C·(cm²·K)^-1, respectively. The PLT thin films could meet the needs for uncooled pyroelectric infrared sensors.