Thickness dependence of the dielectric susceptibility of ferroelectric thin films

Wl, Zhong; Bd, Qu; Zhang, Pl; Wang, Yg

doi:10.1103/physrevb.50.12375

Cited by 72 publications

(50 citation statements)

References 20 publications

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“…50 Therefore, the revealed electrode effect on the dielectric response of Ba 0.7 Sr 0.3 TiO 3 films could be partly due to the polarization variations near the interfaces. According to the phenomenological theory, 17 the increase of the film permittivity with decreasing thickness, which was observed for SRO samples, can be attributed to the polarization suppression near the film surfaces ͑␦ Ͼ 0͒. At the same time, the polarization enhancement at the Ba 0.7 Sr 0.3 TiO 3 / Pt interface ͑␦ Ͻ 0͒ is required to explain the thickness dependence of the dielectric response obtained for the Pt samples.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

“…Second, we ignored the intrinsic size effect on the film permittivity 17 resulting from local changes of the polarization state near the ferroelectric/electrode interfaces. 16 The thickness dependence of the permittivity caused by this effect also modifies the intercept c t −1 ͑t → 0͒.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

“…Such a "dead" layer not necessarily has a different microstructure ͑e.g., due to reconstruction or high density of defects͒, because the intrinsic surface effect on the polarization 16 may also reduce the local dielectric permittivity. 17,18 The existence of a built-in electric field at the film/electrode interface represents another possible origin of suppressed dielectric response in the subsurface layer. 2,18 On the other hand, the interfacial capacitance may mostly originate in the finite electronic screening length of metallic electrodes.…”

Section: Introductionmentioning

confidence: 99%

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Thickness dependence of intrinsic dielectric response and apparent interfacial capacitance in ferroelectric thin films

Pertsev

Dittmann

Plonka

et al. 2007

Journal of Applied Physics

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We studied theoretically the influence of the progressive strain relaxation and the depolarizing-field effect on the thickness dependence of the out-of-plane dielectric response of epitaxial ferroelectric thin films sandwiched between extended metal electrodes. The calculations show that the inverse of the measured capacitance varies with the film thickness almost linearly in the most part of the thickness range at the majority of temperatures. Extrapolation of this linear dependence to zero thickness usually gives considerable nonzero intercept even in the absence of nonferroelectric interfacial layers. Remarkably, such apparent “interfacial capacitance” in a certain temperature range becomes negative. The physical meaning of the effective dielectric constant, which can be extracted from the slope of the reciprocal capacitance thickness dependence, is also analyzed. The theoretical predictions are compared with the experimental data obtained for single-crystalline SrRuO3∕Ba0.7Sr0.3TiO3∕SrRuO3 and Pt∕Ba0.7Sr0.3TiO3∕SrRuO3 thin-film capacitors.

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Section: Comparison With Experimentsmentioning

confidence: 99%

Section: Comparison With Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thickness dependence of intrinsic dielectric response and apparent interfacial capacitance in ferroelectric thin films

Pertsev

Dittmann

Plonka

et al. 2007

Journal of Applied Physics

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“…[1][2][3][4][5][6][7][8][9][10][11][12] As the dimensions (both lateral and vertical direction) of the perovskite layer decreases, the fundamental question of size dependence becomes crucial. From a theoretical point of view, two models have been traditionally used to describe size effects, namely an "intrinsic" effect 9,10,13 and a "depoling field" effect.…”

mentioning

confidence: 99%

Size effects in ultrathin epitaxial ferroelectric heterostructures

Valanoor

Prasertchoung

Zhao

et al. 2004

Applied Physics Letters

114

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In this letter we report on the effect of thickness scaling in model PbZr 0.2 Ti 0.8 O 3 ͑PZT͒ / SrRuO 3 heterostructures. Although theoretical models for thickness scaling have been widely reported, direct quantitative experimental data for ultrathin perovskite ͑Ͻ10 nm͒ films in the presence of real electrodes have still not been reported. In this letter we show a systematic quantitative experimental study of the thickness dependence of switched polarization in (001) epitaxial PZT films, 4 to 80 nm thick. A preliminary model based on a modified Landau Ginzburg approach suggests that the nature of the electrostatics at the ferroelectric-electrode interface plays a significant role in the scaling of ferroelectric thin films. The effect of thickness scaling in ferroelectrics has recently been of immense interest. [1][2][3][4][5][6][7][8][9][10][11][12] As the dimensions (both lateral and vertical direction) of the perovskite layer decreases, the fundamental question of size dependence becomes crucial. From a theoretical point of view, two models have been traditionally used to describe size effects, namely an "intrinsic" effect 9,10,13 and a "depoling field" effect. 4,5,14,15 Experimentally Tybell et al. 8 qualitatively showed that even a 4-nm-thick epitaxial PbZr 0.2 Ti 0.8 O 3 (PZT) film on Nb:STO is ferroelectric. However a direct experimental quantification of the ferroelectric polarization, particularly for films in the sub-10 nm thickness range has not been reported. For such ultrathin films direct experimental quantification of size effects are complicated by extrinsic effects such as leakage and therefore methods other than the traditional P -E hysteresis loop have been reported to characterize the stability of the polar state. 1,7 This letter presents experimental measurements of the switched polarization in PZT films of thickness down to 4 nm, in the presence of real electrodes.A 70-nm-thick SRO layer was grown on STO at 650°C followed by the PZT layer via pulsed laser deposition. The deposition was carried out at 100 mTorr of oxygen and the sample was cooled down from growth temperature 1 atm of oxygen. In order to avoid complications from 90°domain formation the PZT films were grown in a thickness range from 4 to 80 nm, for which they are entirely c-axis oriented. The switchable polarization was measured using a Radiant Technologies Precision Premier system at 16 kHz (hysteresis loops) and an AFM based pulsed probing technique with conductive Pt-Ir tips was employed to measure the pulsed polarization. 16 We focused on the PZT ͑0/20/80͒ composition, since it has an in-plane lattice parameter of 3.94 Å, 17 which is closely lattice matched to SRO͑3.93 Å͒. Figure 1(a) is a low magnification TEM image of a 4 nm (nominal) thick film; the interfaces between SRO and PZT are sharp, identified as dashed lines in the high resolution image, Fig. 1(b). The electrode-ferroelectric interface shows a significantly reduced dislocation density, attributed to the small lattice mismatch (0.7%) at growth temperature of 600...

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“…The origin of the reduced dielectric response in SrTiO 3 thin films was discussed by Ostapchuk et al [28]. Using the phenomenological theory, Zhong et al [29] and Chen et al [30] have calculated the size and surface effects on the dielectric susceptibility of ferroelectric thin films and found that the peak of dielectric susceptibility shifts to lower temperature due to the presence of the surface layers. Wang et al [31] and Qu et al [32] have studied the ferroelectric thin films described by the transverse Ising model (TIM) under the mean-field approximation.…”

Section: Introductionmentioning

confidence: 99%

Dielectric properties of ferroelectric thin films with surface transition layers

Chen

Lü

Cui

et al. 2008

Physica A: Statistical Mechanics and its Applications

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By taking into account surface transition layers (STL), the dielectric properties of ferroelectric thin films described by the transverse Ising model are discussed in the framework of the mean field approximation. Functions of the intra-layer and inter-layer couplings are introduced to characterize STL, which makes the model more realistic compared to previous treatment of surface layers using uniform surface exchange interactions and a transverse field. The effects of physical parameters on the dielectric properties are quantified. The results obtained indicate that STL has very strong influence on the dielectric properties of ferroelectric thin films. Some of our theoretical results are in accord with the available experimental data.

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Thickness dependence of the dielectric susceptibility of ferroelectric thin films

Cited by 72 publications

References 20 publications

Thickness dependence of intrinsic dielectric response and apparent interfacial capacitance in ferroelectric thin films

Thickness dependence of intrinsic dielectric response and apparent interfacial capacitance in ferroelectric thin films

Size effects in ultrathin epitaxial ferroelectric heterostructures

Dielectric properties of ferroelectric thin films with surface transition layers

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