Effect of MgO Dopant on the Microstructure and Dielectric Properties of rf-Sputtered Ba[sub 0.5]Sr[sub 0.5]TiO[sub 3] Thin Films

Chiu, Ming‐Chih; Lee, Ying-Chieh; Shieu, Fuh‐Sheng

doi:10.1149/1.2048167

Cited by 16 publications

(5 citation statements)

References 27 publications

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“…This 1% dopant rate has been found to be optimum 7 for reducing the leakage current, the dielectric losses, and the low frequency charge carrier diffusion. 7,10,11 Platinum top electrodes have been deposited by RF sputtering in order to realize a MIM capacitor. The capacitance and the dielectric loss factor (tan d) have been measured using an Agilent 4294A impedance meter at 100 kHz.…”

Section: Methodsmentioning

confidence: 99%

Decomposition of the different contributions to permittivity, losses, and tunability in BaSrTiO3 thin films using the hyperbolic law

Nadaud

Borderon

Renoud

et al. 2016

Journal of Applied Physics

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In this paper, the different contributions to the permittivity of a 1% manganese-doped BaSrTiO 3 thin film are presented as a function of the applied DC field. The hyperbolic law has been used to discern the lattice, domain wall vibration, and pinning/unpinning contributions. This decomposition permits us to study the weight of the respective contribution in the total permittivity, the losses, and the tunability. By determining the figure of merit (FoM) of each contribution, the ratio between tunability and losses, it is possible to identify the phenomenon which should be limited or enhanced in order to optimize the material's dielectric properties. It is shown that the tunability of the domain wall contribution (approximately 80%) is very important compared to the lattice contribution (41%), the associated dissipation factor, however, is also much larger (0.2 instead of 0.014). Even if the domain wall contribution has been shown to be weak in the investigated thin film (less than 3% in permittivity and tunability), the weight of the losses is not negligible (around 18%). Hence, the domain contribution has to be limited in order to conserve a high FoM for the material. Moreover, it is shown that the AC field used for the material's characterization is important because it governs the weight of the domain wall losses and thus the FoM. V C 2016 AIP Publishing LLC.

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Section: Methodsmentioning

confidence: 99%

Decomposition of the different contributions to permittivity, losses, and tunability in BaSrTiO3 thin films using the hyperbolic law

Nadaud

Borderon

Renoud

et al. 2016

Journal of Applied Physics

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“…The dielectric properties are strongly related to the quality of the material and more especially to the presence of defects. In ferroelectric thin films, oxygen vacancies are the predominant defects which participate to the conduction losses by releasing free electrons and generating dangling bonds in the material structure 5,6 . However, in order to minimize these losses, it is possible to perform doping of the material by substitution of one of the lattice ions by an ion of different valence.…”

Section: Introductionmentioning

confidence: 99%

Effect of manganese doping of BaSrTiO3 on diffusion and domain wall pinning

Nadaud

Borderon

Renoud

et al. 2015

Journal of Applied Physics

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In the present paper, the influence of manganese doping on the dielectric properties of BaSrTiO 3 thin films is presented. The real and imaginary parts of the material's permittivity have been measured in a large frequency range (100 Hz-1 MHz) and as a function of the electric field. The tunability and the figure of merit of the material have been obtained from the measurement of the permittivity under an applied DC bias electric field. For the undoped material, the dielectric losses become important for a large DC bias which leads to breakdown. At a suitable dopant rate, this effect disappears. In order to better understand the origin of the related phenomena, we measure the permittivity as a function of the AC excitation amplitude and we decompose the obtained permittivity with the hyperbolic law. This enables to extract the different contributions of the bulk (low frequency diffusion and high frequency lattice relaxation) and of the domain wall motions (vibration and pinning/unpinning) to the material's dielectric permittivity and to understand the effect of manganese doping on each contribution. Knowledge of the related mechanisms allows us to establish the optimum dopant rate (mainly conditioned by the lattice contribution) and to reduce the domain wall motion, which finally is beneficial for the desired properties of the ferroelectric thin film. A particular attention is paid to low frequency diffusion, an especially harmful effect when a DC biasing is mandatory (tunable electronic component in mobile telecommunication devices for example).

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“…1% manganese doping in substitution of the Ti-ions has been employed in order to reduce the low frequency diffusion and high frequency losses [14]. Electron acceptor doping permits us to compensate for oxygen vacancies which are the main defects that contribute to the conduction losses in ferroelectric thin films [14][15][16]. Moreover, manganese doping helps reduce the domain wall motion contribution to the permittivity which is very dissipative [14].…”

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confidence: 99%

Temperature stable BaSrTiO3 thin films suitable for microwave applications

et al. 2015

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In this paper, the properties of an optimized BaSrTiO 3 thin film, deposited on an alumina substrate using a sol-gel process, are presented. The real and imaginary parts of the permittivity and the tunability have been measured over 7 decades of frequency and in a temperature interval of 320• C, which provides a good knowledge of the material properties for microwave applications. The dielectric properties of the films show a good stability in frequency and in temperature. From −80• C to 20• C, the permittivity changes less than 2% and from −75 • C to 100• C, the tunability stays higher than 90% of its maximum value.The frequency dependence of the relative permittivity of the thin film is rather small since it only varies from 375 at 1 kHz to 350 at 5 GHz. As a main consequence, the tunability which attains almost 60% under a bias field of 400 kV/cm, is very stable in frequency up to 5 GHz. The dielectric losses tan δ, measured up to 1 GHz, stay below 0.02 for the complete frequency range. Although the material is in the ferroelectric phase, the hysteresis effect is quite negligible, which results in a well-determined permittivity value for a given electric bias field. The characterized thin film has been integrated into a reflectarray cell allowing a dynamic control of the reflected phase. The measured phase-shift value is close to the simulated one, showing the performance of the material.

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Effect of MgO Dopant on the Microstructure and Dielectric Properties of rf-Sputtered Ba[sub 0.5]Sr[sub 0.5]TiO[sub 3] Thin Films

Cited by 16 publications

References 27 publications

Decomposition of the different contributions to permittivity, losses, and tunability in BaSrTiO3 thin films using the hyperbolic law

Decomposition of the different contributions to permittivity, losses, and tunability in BaSrTiO3 thin films using the hyperbolic law

Effect of manganese doping of BaSrTiO3 on diffusion and domain wall pinning

Temperature stable BaSrTiO3 thin films suitable for microwave applications

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