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Title: Dielectric and tunable properties of K-doped Ba[sub 0.6]Sr[sub 0.4]TiO₃ thin films fabricated by sol-gel method
Authors: Sun, Xiaohua
Zhu, Bailin
Liu, Tao
Li, Meiya
Zhao, Xingzhong
Wang, Danyang
Sun, Chengliang
Chan, Helen L. W.
Subjects: Potassium
Barium compounds
Strontium compounds
Dielectric thin films
Dielectric materials
Sol-gel processing
Differential thermal analysis
Surface morphology
Chemical analysis
X-ray diffraction
Atomic force microscopy
Grain size
Surface roughness
Dielectric losses
Issue Date: 25-Apr-2006
Publisher: American Institute of Physics
Source: Journal of applied physics, 25 Apr. 2006, v. 99, 084103, p. 1-6
Abstract: Ba[sub 0.6]Sr[sub 0.4]TiO₃ (BST) thin films doped by K (BSTK) from 1 to 20 mol % were fabricated by sol-gel method on a Pt/TiO₂/SiO₂/Si substrate. Thermal evolutionary process of the Ba[sub 0.6]Sr[sub 0.4]TiO₃ and Ba[sub 0.6]Sr[sub 0.4])[sub 0.95]K[sub 0.05]TiO₃ dry gel was carried out by thermogravimetry and differential thermal analysis system. The structure and surface morphology of BST thin films were investigated as functions of K concentration by x-ray diffraction and atomic force microscopy. The dielectric measurements were conducted on metal-insulator-metal capacitors at the frequency from 100 Hz to 1 MHz. The K concentration in BST thin films has a strong influence on the material properties including surface morphology and dielectric and tunable properties. The grain size, surface root-mean-square roughness, dielectric constant, dissipation factor, and tunability all increased with increasing K content up to 7.5 mol % and then decreased with increasing K content from 7.5 to 20 mol % in the BSTK thin films at 1 MHz. The effects of K doping on the microstructure and dielectric and tunable properties of Ba[sub 0.6]Sr[sub 0.4]TiO₃ thin films were analyzed. The (Ba[sub 0.6]Sr[sub 0.4])[sub 92.5%]K[sub 7.5%]TiO₃ thin film exhibited the highest dielectric constant of 1040 and the largest tunability of 73.6%. The dielectric constant, dielectric loss, and tunability of K-doped BST thin films with the optimal K content of 5 mol % were about 971, 0.023, and 69.96%, respectively. In addition, its figure of merit showed a maximum value of approximately 28.52.
Rights: © 2006 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in X. Sun et al. J. Appl. Phys. 99, 084103 (2006) and may be found at
Type: Journal/Magazine Article
DOI: 10.1063/1.2189976
ISSN: 0021-8979
Appears in Collections:AP Journal/Magazine Articles

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