Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9784117 | Materials Science and Engineering: B | 2005 | 6 Pages |
Abstract
Compositionally-graded (Ba1âxSrx)TiO3 thin films (x varying from 0 to 0.25) were epitaxially grown by pulsed-laser deposition on (1Â 0Â 0)MgO single-crystal substrates with a conductive La0.5Sr0.5CoO3 layer as bottom electrode. The crystallinity and epitaxial growth behavior of the graded BST films were investigated by X-ray diffraction and transmission electron microscopy. The results show that the graded films are (1Â 0Â 0)-oriented with an orientation relationship of (1Â 0Â 0)[0Â 1Â 0]BST//(1Â 0Â 0)[0Â 1Â 0]MgO. Cross-sectional TEM images show that graded BST films grow with a columnar structure and a surface roughness of 10Â nm. From planar TEM images granular and/or polyhedral shaped grains are observed with an average grain size of 65Â nm. At room temperature, the dielectric constant and dielectric loss at 10Â kHz for the graded film were 953 and 0.0103, respectively. A broad and flat profile of the dielectric constant versus temperature was demonstrated in the graded film. This was attributed to the presence of the compositional and/or residual strain gradients in the epitaxial compositionally-graded films. With such a graded structure, it is possible to build dielectric thin film capacitors with almost negligible temperature dependence of the capacitance, thereby operating without the need for controlling the environmental temperatures.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Electronic, Optical and Magnetic Materials
Authors
Xinhua Zhu, Jianmin Zhu, Shunhua Zhou, Zhiguo Liu, Naiben Ming, Helen Lai-Wah Chan, Chung-Loong Choy, Kin-Hung Wong, Dietrich Hesse,