Epitaxial growth of ferroelectric Ba1−xSrxTiO3thin films for room temperature tunable microwave devices

Chen, C. L.; Shen, Jiale; Chen, S. Y.; Zhang, Z.; Luo, Guoping; Chu, W. K.; Chu, C. W.

doi:10.1080/00150190108016255

Cited by 4 publications

(4 citation statements)

References 11 publications

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“…This was confirmed by the rocking measurements from the (001) reflections of the BST films deposited on (001) LAO and (001) MgO substrates at almost the same growth conditions. 56 The value of the full-width at half-maximum (FWHM) was measured to be less than 0.15°for the film on (001) LAO, but was about 0.3°for the BST film on MgO. The smaller FWHM value for the BST film on (001) LAO indicates that the as-grown BST film on LAO has a better single-crystallinity quality than that of BST films on MgO.…”

Section: Interfacial Structuresmentioning

confidence: 98%

“…Such strain energy also makes it difficult to grow high-quality epitaxial BST films on MgO substrates. Chen et al 56,57 and Gao et al 58 have examined the interface behavior of the epitaxial (Ba 0.6 Sr 0.4 )TiO 3 films on the (001) MgO and (001) LAO substrates by using x-ray diffraction and electron microscopy. Their results showed that the asgrown film has a high degree of crystallinity and good in-plane orientation: <100> BST //<100> MgO and (100) BST //(100) MgO , as confirmed by x-ray diffraction and selected-area electron diffraction patterns.…”

Section: Interfacial Structuresmentioning

confidence: 99%

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Recent progress of (Ba,Sr)TiO3 thin films for tunable microwave devices

Zhu

Zhou

et al. 2003

Journal of Elec Materi

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The (Ba 1-x Sr x )TiO 3 (BST) ferroelectric thin films exhibit outstanding dielectric properties, even at high frequencies (Ͼ1 GHz), and large, electric-field dielectric tunability. This feature makes them suitable for developing a new class of tunable microwave devices. The dielectric properties and dielectric tuning property of BST thin films are closely related to the film compositions, substrate types, and post-deposition process. The successful implementation of BST films as high-frequency dielectrics in electrically tunable microwave devices requires a detailed understanding of both their processing and material properties. This paper will review the recent progress of BST thin films as active dielectrics for tunable microwave devices. The technical aspects of BST thin films, such as processing methods, post-annealing process, film compositions, film stress, oxygen defects, and interfacial structures between film and substrate, are briefly reviewed and discussed with specific samples from the recent literature. The major issues requiring additional investigations to improve the dielectric properties of BST thin films for tunable microwave applications are also discussed.

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Section: Interfacial Structuresmentioning

confidence: 98%

Section: Interfacial Structuresmentioning

confidence: 99%

Recent progress of (Ba,Sr)TiO3 thin films for tunable microwave devices

Zhu

Zhou

et al. 2003

Journal of Elec Materi

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“…However, the large dielectric loss and the large dielectric constants (>1000) become the road block for tunable device developments. 3,[5][6][7][8][9] Recently, thin film of a nonferroelectric material, (Bi 1.5 Zn 0.5 )(Zn 0.5 Nb 1.5 )O 7 (BZN), with a cubic A 2 B 2 O 7 pyrochlore structure, displays very low dielectric loss ($5 Â 10 À4 ) and a medium permittivity (170-200) which can be tuned by the applied voltage. [10][11][12] In terms of physics, the cubic pyrochlore structure can tolerate considerable Zn substitution on the A site, and the inhomogeneous distribution of Zn 2þ atoms and vacancies on the Bi 3þ sites is demonstrated to enhance the additional random fields, rendering the multiwall potentials to be widely distributed in heights, and associated transition rates for Bi 3þ and Zn 2þ cations.…”

Section: Introductionmentioning

confidence: 99%

Structure, composition and microwave dielectric properties of bismuth zinc niobate pyrochlore thin films

Wang

Ren

Zhan

et al. 2014

Journal of Applied Physics

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(Bi1.5Zn0.5)(Zn0.5Nb1.5)O7 (BZN) pyrochlore thin films were deposited onto both Pt/TiO2/SiO2/Si and polycrystalline alumina substrates using pulsed laser deposition technique and then post-annealed using rapid thermal processing. The deposition temperature varies from 300 °C to 600 °C, and all the BZN films showed cubic pyrochlore structure after annealing at 650 °C for 30 min in air. The influence of the substrate associated with crystal structure is significant in the as-deposited films and disappears after post-annealing. The dielectric properties as a function of frequency up to the microwave frequency in both films were measured by LCR meter and split-post dielectric resonator technique. It is found that the BZN film deposited at 400 °C and post-annealed at 650 °C shows excellent dielectric properties with low loss in the microwave frequency range. This result indicates that the BZN thin film is a potential microwave material.

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“…[8][9][10] For example the dielectric tunability is larger for (111) oriented films compared to (001) and the best electrical properties are obtained on (001) epitaxial BST films. 11,12 In this context, it is important to compare the structural and the microstructural properties of BST films exhibiting (001) and (111)-preferred orientations, as fiber-or epitaxial textures. The residual stresses in the films, which are certainly different between films differently oriented, have also a non-negligible effect on the films tunability.…”

Section: Introductionmentioning

confidence: 99%

X-ray combined analysis of fiber-textured and epitaxial Ba(Sr,Ti)O3 thin films deposited by radio frequency sputtering

Rémiens¹,

Yang

Ponchel³

et al. 2011

Journal of Applied Physics

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A complete study is given in this paper on the structural properties of Ba(Sr,Ti)O3 (BST) thin films which present various preferred orientations: (111) and (001) fiber and epitaxial textures. The films are deposited in situ at 800 °C by sputtering on Si/SiO2/TiOx/Pt substrates and the orientation is controlled by monitoring the concentration of O2 in the reactive plasma or by prior deposition of a very thin TiOx buffer layer between BST films and substrates. The epitaxial films are obtained on (001)-alpha-Al2O3 substrates covered with TiOx buffer layers. In order to analyze finely the preferred orientations, the texture, the microstructural features, and the anisotropy-related quantities such as residual stresses in the films, the conventional Bragg−Brentano θ - 2θ x-ray diffraction diagrams is shown not to be sufficient. So, we systematically used x-ray combined analysis, a recently developed methodology which gives access to precise determination of the structure (cell parameters and space group) of the films, their orientation distributions (texture strengths and types) and mean crystallite sizes, their residual stresses. This fine structural analysis shows important modifications between the film qualities which induce differences in BST films electrical behavior, permittivity, loss tangent, and tunability.

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Epitaxial growth of ferroelectric Ba_1−xSr_xTiO₃thin films for room temperature tunable microwave devices

Cited by 4 publications

References 11 publications

Recent progress of (Ba,Sr)TiO3 thin films for tunable microwave devices

Recent progress of (Ba,Sr)TiO3 thin films for tunable microwave devices

Structure, composition and microwave dielectric properties of bismuth zinc niobate pyrochlore thin films

X-ray combined analysis of fiber-textured and epitaxial Ba(Sr,Ti)O3 thin films deposited by radio frequency sputtering

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