Ba_(0.64)Sr_(0.36)TiO_3薄膜的介电与热释电性能的研究

DIELECTRIC AND PYROELECTRIC PROPERTIES OF Ba_(0.64)Sr_(0.36)TiO_3 THIN FILMS BY SOL-GEL ON PLATINUM COATED SILICON

应用溶胶 -凝胶工艺在Pt/SiO2 /Si(10 0 )衬底上制备了Ba0 .6 4Sr0 .36 TiO3薄膜 ,研究了薄膜的结构与电学性能。实验结果表明 :Ba0 .6 4·Sr0 .36 TiO3薄膜经 70 0℃热处理 1h ,薄膜呈现出钙钛矿结构。当测试频率为 2 0 0Hz时 ,薄膜的介电常数和损耗因子分别为 5 92和 0 .0 2 8。在40℃时 ,Ba0 .6 4Sr0 .36 TiO3薄膜存在一扩散铁电 -顺电相变。在室温 (2 5℃ )、10 0kHz条件下测试薄膜的C -V特性得到一“蝶形”曲线 ,表明Ba0 .6 4Sr0 .36 TiO3薄膜在室温下处于铁电相 ,且当直流偏压从 -5V增至 + 5V期间 ,薄膜电容由 495 pF增至 110 8pF。热释电性能测试结果表明 :室温下Ba0 .6 4Sr0 .36 TiO3薄膜的热释电系数为 1860 μC/(m2 ·K) ,材料的优值为 3 7.4μC/(m3·K) ,这些结果表明 :应用溶胶 -凝胶工艺制备的Ba0 .6 4Sr0 .36

Ba 0.64 Sr 0.36 TiO 3 thin films were prepared by sol-gel method on a platinum-coated silicon substrate. The structure and electrical properties of sol-gel derived barium-strontium-titanate (Ba 0.64 Sr 0.36 TiO 3) thin films were investigated. The as-fired thin films were found to be amorphous, and the films crystallized to a perovskite structure after a post deposition annealing at 700 ℃ for 1 h in air. The dielectric constant and dissipation factor for the Ba 0.64 Sr 0.36 TiO 3 thin films at 200 Hz were 592 and 0.028, respectively. The temperature dependence of dielectric constant and dissipation factor exhibited a diffused ferroelectric to paraelectric phase transition at 40 ℃. The ferroelectric nature of the films at 25 ℃ is confirmed by the existence of butterfly_shaped C-V curves caused by switching of the ferroelectric domains. The capacitance changes from 495 to 1108 pF with the applied voltage in the range of -5 to +5V at 100 kHz. The pyroelectric coefficient at 25 ℃ is 1 860 μC/(m 2·K), and the figure-of-merit of this film is 37.4 μC/(m 3·K). The high pyroelectric coefficients and the greater figures of merit of the Ba 0.64 Sr 0.36 TiO 3 thin films make it possible to be used for thermal infra-red detection and imaging.