Voltage tunable capacitors using high temperature superconductors and ferroelectrics

Wu, Houzheng; Zhang, Zhihang; Barnes, Frank S.; Jackson, Charles M.; Kain, A.Z.; Cuchiaro, J. D.

doi:10.1109/77.317831

Cited by 53 publications

(9 citation statements)

References 8 publications

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“…An interdigital finger structure can be used to increase the capacitance [21,22]. The properties of the ferroelectric materials can be extracted from the measured capacitance and dielectric losses using a conformal mapping technique, such as that described below [23].…”

Section: Low-frequency Propertiesmentioning

confidence: 99%

“…The loss tangent of STO single crystals is of the order 2 × 10 −4 at 77 K [24], but in the thin-film forms this is much bigger and almost all manufacturers quote loss tangents in the range 0.01-0.1 [17,19]. This high loss tangent also applies to SBT thin films, irrespective of their composition [15,18,19,23,25]. This is probably the main area of concern in the development of ferroelectric films for microwave applications, where the losses need to be reduced further if such films are to be used in the widespread applications mentioned previously.…”

Section: Low-frequency Propertiesmentioning

confidence: 99%

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Thin-film ferroelectric microwave devices

Lancaster

Powell

Porch

1998

Supercond. Sci. Technol.

218

113

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When an electric field is applied to a ferroelectric material, the microwave permittivity undergoes a substantial change. This change in permittivity can be utilized in microwave devices to produce frequency-agile functions. This paper is a comprehensive review of the work on ferroelectric materials; this includes models of the ferroelectric permittivity and loss tangent, as well as methods of measurement of these properties. New measurements are presented on thin-film strontium titanate and single-crystal strontium barium titanate substrates. These results are compared with the model. A brief discussion is given of the applications of ferroelectric material in microwave devices.

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Section: Low-frequency Propertiesmentioning

confidence: 99%

Section: Low-frequency Propertiesmentioning

confidence: 99%

Thin-film ferroelectric microwave devices

Lancaster

Powell

Porch

1998

Supercond. Sci. Technol.

218

113

View full text Add to dashboard Cite

show abstract

“…capacitors [1][2][3] and chemical sensors [4][5][6][7][8][9] that rely on change in material properties due to external stimuli. For devices that utilize the piezoelectric effect, such as surface acoustic wave devices [10][11][12] and piezoelectric transducers [13,14], the dielectric properties must be understood in order to describe the electric field and coupling to the piezoelectric effect.…”

Section: Introductionmentioning

confidence: 99%

“…A similar approach of generating additional potentials, known as the method of recursive images, has recently been revisited by Diaz and Igreja [17], where unphysical boundary conditions at the interface with the electrode were used in order to preserve the potential at the electrodes. Wu et al [1] developed an alternate approach, known as the parallel partial capacitance (PPC) model, where the interfaces are instead ignored, and the structure is divided into partial structures and the capacitance of each partial structure is evaluated separately. Conformal mapping approaches of increasing accuracy were developed by Gevorgian et al [18] and Igreja and Dias [19].…”

Section: Introductionmentioning

confidence: 99%

A unified approach for the calculation of in-plane dielectric constant of films with interdigitated electrodes

Reader

Hanke

Halvorsen

et al. 2020

Smart Mater. Struct.

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Interdigitated electrodes (IDEs) on dielectric films is an important electrode design in electrical components such as transducers and sensors. Further development and use of IDEs for characterization of the in-plane properties of dielectric films requires models for the capacitance, particularly when used in a multilayer stack. Previous models for the capacitance have permitted erroneous boundary conditions between layers with associated limitations to accuracy. In this work we present a new model based on fulfilling the boundary conditions between layers with different dielectric constant. We further demonstrate how the model can be used to calculate the in-plane dielectric constant and polarization of BaTiO3 films. The model is shown to outperform previous models using both the experimental data from BaTiO3 films on SrTiO3 substrates and finite element method simulations of the corresponding case. One important advantage compared to previous work is that the new model provides good results regardless of film thickness.

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“…[9][10][11][12][13][14][15] On the other hand, some reports showed that BST thin films exhibited relatively high EO effects 16,17 though EO coefficients reported in literatures were not consistent with each other. [9][10][11][12][13][14][15] On the other hand, some reports showed that BST thin films exhibited relatively high EO effects 16,17 though EO coefficients reported in literatures were not consistent with each other.…”

Section: Introductionmentioning

confidence: 99%

Dielectric tunability and electro-optic effect of Ba0.5Sr0.5TiO3 thin films

Takeda

Muraishi

Hoshina

et al. 2010

Journal of Applied Physics

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We elucidated the relationship between the dielectric tunability and the electro-optic (EO) effect. A new measurement system for EO effect and dielectric permittivity (εr) was developed to investigate the accurate correlation between EO and dielectric properties of epitaxial barium strontium titanate, Ba0.5Sr0.5TiO3 (BST) thin films grown on SrTiO3 (STO) substrates. The BST films had a strained lattice with a large lattice parameter along the thickness direction. Small birefringence was induced in the as-deposited film by the alignment of the c-axis in the film plane. The tunability of dielectric permittivity calculated from the complex voltage and current with planer electrodes reached to 53.1%, and the tunability of birefringence by EO effect was 0.6%. The birefringence change from EO effect was much lower than the tunability of dielectric permittivity. Therefore, there is no strong correlation between the dielectric tunability and EO effect, and the materials with high tunability do not always exhibit high EO effect. Finally, we discussed how to obtain the materials with high EO effect considering these results.

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Voltage tunable capacitors using high temperature superconductors and ferroelectrics

Cited by 53 publications

References 8 publications

Thin-film ferroelectric microwave devices

Thin-film ferroelectric microwave devices

A unified approach for the calculation of in-plane dielectric constant of films with interdigitated electrodes

Dielectric tunability and electro-optic effect of Ba0.5Sr0.5TiO3 thin films

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