Medium permittivity bismuth zinc niobate thin film capacitors

Thayer, R.; Randall, Clive A.; Trolier-McKinstry, Susan

doi:10.1063/1.1590415

Cited by 127 publications

(80 citation statements)

References 20 publications

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“…For room temperature applications, thin films of ferroelectrics such as (Ba,Sr)TiO 3 (BST) have been extensively studied [1]. Recently, thin films of a nonferroelectric material, Bi 1.5 Zn 1.0 Nb 1.5 O 7 (BZN), which has the cubic pyrochlore structure [2] and a medium permittivity (170 -200), have attracted interest for tunable applications due to their very low losses (~ 5¥10 -4 [3]) and large tunabilities (55 %) [3][4][5][6] at low frequencies (~ 1 MHz). The tunability is defined as e max -e min ( ) e max , where † e min is the minimum measured permittivity at the maximum applied field, and † e max is the dielectric constant at zero bias.…”

Section: Introductionmentioning

confidence: 99%

Microwave dielectric properties of tunable capacitors employing bismuth zinc niobate thin films

Park

Stemmer

et al. 2005

Journal of Applied Physics

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Parallel plate capacitors employing Bi1.5Zn1.0Nb1.5O7 (BZN) thin films with the pyrochlore structure were fabricated on platinized sapphire substrates. The total device quality factor and capacitance were analyzed in the microwave frequency range (up to 20 GHz) by measuring reflection coefficients with a vector network analyzer. The parasitics due to the probe pads were extracted from the measurements. The total device quality factor, which included losses from the dielectric and the electrodes, was more than 200 up to 20 GHz for devices with an area of 100μm2. Based on the frequency dependence of the impedance, series losses of unknown origin appear to dominate the device quality factor at higher frequencies. No significant dispersion in the device capacitance, as would be associated with a dielectric relaxation of BZN, was measured. The large electric field tunability of the permittivity of BZN films and the high device quality factors make these films attractive for voltage controlled microwave devices.

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Section: Introductionmentioning

confidence: 99%

Microwave dielectric properties of tunable capacitors employing bismuth zinc niobate thin films

Park

Stemmer

et al. 2005

Journal of Applied Physics

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“…Recently, Bi 1.5 Zn 1.0 Nb 1.5 O 7 (BZN) thin films with the cubic pyrochlore structure have attracted interest for integrated capacitor applications because of their relatively high permittivity (~170-220) [1][2][3][4] and dielectric loss tangents (tan ) that were as low as 5 × 10 -4 [1]. Furthermore, BZN thin films exhibit an electric field tunable dielectric constant [1][2][3][4].…”

mentioning

confidence: 99%

Influence of strain on the dielectric relaxation of pyrochlore bismuth zinc niobate thin films

Klenov

Stemmer

2004

Applied Physics Letters

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Bi 1.5 Zn 1.0 Nb 1.5 O 7 (BZN) films were deposited by rf magnetron sputtering on different substrates to systematically vary the film stress due the thermal mismatch between BZN and the substrate. Substrates included Pt/SiO2 covered silicon, vycor glass, magnesium oxide, and sapphire. The BZN film microstructures (orientation, grain size, and roughness) were similar on the different substrates. Measurements of the permittivity and dielectric loss tangent were carried out between 80 and 300 K at frequencies between 10 kHz and 10 MHz. Films that were under a moderate tensile stress showed a low-temperature dielectric relaxation, associated with a dielectric loss peak and drop in permittivity, at ∼100 K. In contrast, the dielectric relaxation was shifted to temperatures below 80 K in films on vycor that were under a large tensile stress. This shift reflected a lowering of the activation energy of the dielectric relaxation processes due to tensile stress. It is expected that films under large tensile stress require higher frequencies than bulk BZN to shift the dielectric relaxation to room temperature, which makes these films attractive for low-loss high-frequency applications.

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“…XRD q-2q scans after the RTA showed that the BZN films crystallized in the cubic pyrochlore structure and were (111) [20]. The short crystallization times likely reflected the relatively low kinetic barrier against crystallization typical for pyrochlore oxides [21].…”

mentioning

confidence: 99%

Low-loss tunable capacitors fabricated directly on gold bottom electrodes

Schmidt

Boesch

et al. 2006

Applied Physics Letters

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At microwave frequencies, conductor losses due to the bottom electrode resistance severely limit the performance of metal-insulator-metal capacitors that employ tunable dielectric thin films. Here we demonstrate that a novel tunable dielectric, bismuth zinc niobate (BZN), can be integrated directly with low-resistivity Au bottom electrodes. The favorable crystallization kinetics allowed for a low thermal budget process compatible with Au electrodes. BZN thin films on Au bottom electrodes showed low dielectric loss tangents of ∼0.0005 and high dielectric tunabilities of ∼50%. The Au/BZN interface was abrupt and free of reaction phases. At high frequencies (>1MHz) the total Au/BZN capacitor device loss was reduced compared to capacitors with Pt bottom electrodes. The low device losses of Au/BZN capacitors revealed a device geometry-dependent loss mechanism that contributed significantly to the device loss at high frequencies.

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Medium permittivity bismuth zinc niobate thin film capacitors

Cited by 127 publications

References 20 publications

Microwave dielectric properties of tunable capacitors employing bismuth zinc niobate thin films

Microwave dielectric properties of tunable capacitors employing bismuth zinc niobate thin films

Influence of strain on the dielectric relaxation of pyrochlore bismuth zinc niobate thin films

Low-loss tunable capacitors fabricated directly on gold bottom electrodes

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