钇梯度掺杂Ba_(0.6)Sr_(0.4)TiO_3薄膜的sol-gel法制备及介电性能

Dielectric Properties of Graded Y-doped Ba_(0.6)Sr_(0.4)TiO_3 Thin Film Prepared by Sol-gel Method

用改进的溶胶-凝胶法(sol-gel)在Pt/Ti/SiO2/Si(S)上制备了各层Y掺杂浓度分别为0.5%/0.6%/0.7%/0.8%/0.9%/1%的上梯度掺杂和1%/0.9%/0.8%/0.7%/0.6%/0.5%下梯度掺杂的Ba0.6Sr0.4TiO3薄膜。X射线衍射(XRD)表明,各薄膜主要沿(110)晶面生长,均为立方钙钛矿结构。相比均匀掺杂薄膜,梯度掺杂薄膜表现出较好的相结构衍射强度及晶化,上梯度薄膜更为显著。原子力显微镜(AFM)表明,梯度掺杂使薄膜的表面形貌得到极大改善,上梯度比下梯度薄膜具有更加光滑致密的表面相貌和更小的表面粗糙度。电压-电容曲线表明,上梯度薄膜介电性能得到明显提高,在零偏压下的电容为28.5pF(介电常数190)、介电损耗为1.63%及40V下的调谐率为52.3%,优质因子为32。

The upgraded Y-doped with concentration of 0.5%/0.6%/0.7%/0.8%/0.9%/1% Ba 0.6 Sr 0.4 TiO 3 thin film and downgraded Y-doped with concentration of 1%/0.9%/0.8%/0.7%/0.6%/0.5% Ba0.6Sr0.4 TiO 3 thin film were prepared on Pt/Ti/SiO2 / Si substrates by an improved sol-gel method. X-ray diffraction shows that all thin films mostly grow along (110) oriented crystal face and are cubic perovskite structure. Graded Y-doped BST thin films exhibit stronger phase-configuration diffraction intensities and crystallization than normal Y-doped BST thin films, and the upgraded Y-doped BST film is the best. Atomic force microscope (AFM) result demonstrates that graded Y-doped BST has better surface morphologies than Y-doped BST. What’s more, upgraded Y-doped film has denser and smoother surface morphologies and smaller roughness than downgraded Y-doped BST film. Voltage-capacitance curves obtained at 40 V and 100 kHz illustrate that upgraded Y-doped BST thin films exhibit markedly improved dielectric properties with capacitance 28.5 pf (permittivity 190) and dielectric loss 1.63% at zero bias, 52.3% tunability at 40 V and merit factor value of 32, meeting the needs of microwave applications.