Voltage shift and deformation in the hysteresis loop of Pb(Zr,Ti)O3 thin film by defects

Lee, Eun Gu; Wouters, Dirk J.; Willems, Gert; Maes, H.E.

doi:10.1063/1.117418

Cited by 79 publications

(50 citation statements)

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“…Possible origins have been suggested, such as oxygen vacancies, [12][13][14][15] lattice mismatch, 16 dopant, and illumination, 17 although it may very well be due to trapped charge carriers in the sample. 12,[18][19][20][21] Similar horizontal shift phenomenon has also been observed in the measurement of bias-field-dependent dielectricity. 2,3 This is probably due to the same mechanisms as that observed in conventional hysteresis measurement.…”

Section: Introductionsupporting

confidence: 51%

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Modeling of bias-field-dependent dielectric properties in ferroelectric thin films

Wong

Tsang

Shin

2005

Journal of Applied Physics

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The bias-field-dependent dielectricity of ferroelectric thin films is studied by use of a multilayer model capable of modeling saturated and unsaturated hysteresis behavior under arbitrary fields. The simulated minor hysteresis loops at different bias fields are used to calculate the variation of dielectric permittivity with the bias field. The -E loops show asymmetric shifting along the field axis when the film is assumed to possess a secondary dielectric layer with trapped charge. Simulated D-E and -E loops are compared with the experimental data on barium zirconate titanate and lead zirconate titanate thin films. In general, the model predictions show reasonably good agreement with experiment. Effects of charge density and the ac measurement field amplitude on the measured permittivity, as well as the dielectric tunability have also been examined.

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Section: Introductionsupporting

confidence: 51%

“…We assume a small nonferroelectric region ͑or dead layer͒ is formed at the ferroelectric film sample-electrode interface. 5 12,[18][19][20][21] which is not necessarily uniform across the dead layer of the sample. In this work, we adopt a multilayered structure to model this configuration for thin films.…”

Section: Multilayer Model For Thin Ferroelectric Filmsmentioning

confidence: 99%

Modeling of bias-field-dependent dielectric properties in ferroelectric thin films

Wong

Tsang

Shin

2005

Journal of Applied Physics

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“…A most notable phenomenon is the large voltage offset along the horizontal ͑electric field͒ axis found in the hysteresis loop measurements. [1][2][3][4][5][6][7][8][9][10][11] The result is a deformed hysteresis loop with asymmetric switching. 6 Many researchers attributed the shift effect to the internal field caused by trapped charge carriers.…”

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confidence: 99%

A possible mechanism of anomalous shift and asymmetric hysteresis behavior of ferroelectric thin films

Wong

Shin

2005

Appl. Phys. Lett.

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We studied theoretically the hysteresis behavior of ferroelectric thin films. The anomalous ferroelectric response is discussed by use of a bilayer model. Electrical conductivities of the films have been taken into account. To model the effects of the inhomogeneity of polarization and permittivity across the interface, the film is assumed to possess a secondary dielectric/ferroelectric phase ͑a dead or passive layer͒ with asymmetric conductivity. This configuration is found to produce large shifting ͑along the field axis͒ and deformation of the measured hysteresis loop. This is a manifestation of the asymmetric conductivity of the material. Theoretical calculation based on this model shows that the observed phenomena of shifted and skewed hysteresis loop in ferroelectric thin films can be explained in this way. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1853520͔The hysteresis behaviors of ferroelectric thin films have attracted great research interest for many years. Their bistable polarization as well as small size are promising characters for developing compact nonvolatile memories. Research studies of the anomalous effects and degradation mechanisms in the hysteresis behavior of ferroelectric thin films are essential for device applications. A most notable phenomenon is the large voltage offset along the horizontal ͑electric field͒ axis found in the hysteresis loop measurements. [1][2][3][4][5][6][7][8][9][10][11] The result is a deformed hysteresis loop with asymmetric switching. 6 Many researchers attributed the shift effect to the internal field caused by trapped charge carriers. [1][2][3][4] Other explanations included domain pinning, 5,6 rectifying effects formed at the ferroelectric-electrode interface 7-9 and the effect of passive layers. [10][11][12] It seems that the definitive mechanism is still not fully understood and the voltage shift may arise from multiple sources. Theoretical models to gain deeper insight using different approaches have been proposed. [11][12][13][14][15] In the absence of a unifying theory to account for all possible origins, we believe that the current theoretical understanding of the shift phenomenon can benefit from further input in terms of ideas and models. This work attempts to model this offset phenomenon by introducing a passive dielectric/ferroelectric layer at the filmelectrode interface. In the framework of the LandauGinzburg theory, the variation of polarization, which is usually more pronounced in thinner films, is modeled by a gradient term and extrapolation lengths in the free energy expression. This approach is suggested to be effectively the same as the existence of a passive layer ͑or dead layer͒. 16 It has been demonstrated that polarization gradient across a ferroelectric film can lead to asymmetric conduction. 17 The spatially varied polarization near the thin film surfaces is then thought to possess asymmetric electrical conductivity, while asymmetric conductivity may not emerge from the "normal" region of the film since the polarization shoul...

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“…The precursor with a Zr/Ti ratio 52/48 and 10% excess Pb was purchased from the Mitsubish Materials Co. After depositing the top Pt electrode at a thickness of 200 nm, PZT and Pt films were dry etched by means of a Tegal® 6540 dry etcher using a gas mixture of Ar-Cl 2 -CF 4 . The size of the patterned capacitors was 100ϫ100 m 2 .…”

Section: Methodsmentioning

confidence: 99%

“…[1][2][3] Despite the large amount of effort in this field, several issues still remain to be solved for the integration of ferroelectric capacitor modules with standard silicon technology. [4][5][6][7][8][9][10][11] The major issues under current investigation are plasma damage, hydrogen-induced damage, and conductive diffusion barriers. Thus, considerable effort has been made to minimize plasma damage in connection with the undesirable effects of damaged layers.…”

Section: Introductionmentioning

confidence: 99%

Improvement in the electrical properties in Pt/Pb(Zr0.52Ti0.48)O3/Pt ferroelectric capacitors using a wet cleaning method

Lee

Park

Chung

et al. 1999

Journal of Applied Physics

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A wet cleaning solution was designed to specifically eliminate nonferroelectric phases, such as pyrochlore, PbO, and the etching damaged layer. Scanning electron microscopy pictures clearly showed that treatment with the cleaning solution completely removed these nonferroelectric phases. After removing the nonferroelectric phases, ferroelectric properties such as remnant polarization, coercive voltage, and leakage current, were remarkably improved. In addition, the wet cleaned ferroelectric capacitors yielded superior endurance against hydrogen-induced damage compared to those of the noncleaned capacitors.

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Voltage shift and deformation in the hysteresis loop of Pb(Zr,Ti)O3 thin film by defects

Cited by 79 publications

References 0 publications

Modeling of bias-field-dependent dielectric properties in ferroelectric thin films

Modeling of bias-field-dependent dielectric properties in ferroelectric thin films

A possible mechanism of anomalous shift and asymmetric hysteresis behavior of ferroelectric thin films

Improvement in the electrical properties in Pt/Pb(Zr0.52Ti0.48)O3/Pt ferroelectric capacitors using a wet cleaning method

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