Ferroelectric polarization and defect-dipole switching in an epitaxial (111) BiFeO3 thin film

Zhao, Boyuan; Chen, Zhihui; Meng, Jianwei; Lü, Hong-Liang; Zhang, David Wei; Jiang, Anquan

doi:10.1063/1.4921808

Cited by 18 publications

(10 citation statements)

References 33 publications

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“…An important mechanism that has not been considered in previous studies is the effect of defect dipoles, which have been widely observed in oxide perovskites. − The formation of native defects, e.g., iodide vacancy, will leave behind a defect dipole in the PbI 6 or SnI 6 octahedron due to an offset of the positive and negative charge centers (Figure a). Defect dipoles can exist in bulk perovskite lattice or on its free surface.…”

Section: Results and Discussionmentioning

confidence: 99%

Carrier-Activated Polarization in Organometal Halide Perovskites

Wang

et al. 2016

J. Phys. Chem. C

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Organometal halide perovskite solar cells exhibit a strong polarization effect under light illumination. This unique property, although widely observed, has not been well understood. In this work, we carried out a systematic investigation on this phenomenon by varying the perovskite composition and device configurations. We find that the light-enhanced strong polarization is a general phenomenon that occurs in all tested perovskite materials. The organic molecular dipoles affect the polarization at high frequency range, while the photoexcited free carriers and the interface between perovskite and its neighboring layers dominate the low-frequency response. In particular, our study suggests that the giant low-frequency capacitance enhancement originates from native defects and their accompanying defect dipoles, which need to be activated by photogenerated charge carriers. The high flexibility of the perovskite lattice facilitates the formation of these defects, and the dipole effect is enhanced at the interface regions where an electric double-layer capacitor is formed. This work sheds light on the understanding of the light-induced polarization mechanisms of perovskite materials.

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Section: Results and Discussionmentioning

confidence: 99%

Carrier-Activated Polarization in Organometal Halide Perovskites

Wang

et al. 2016

J. Phys. Chem. C

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“…The sub-surface charge can be associated with accumulation of charged defects near the surface [12,59] and/or alignment of defect dipoles under the intrinsic domain depolarizing field. [6,60,61] The existence of the mobile charge defects in BFO is well-known, while details of the defect chemistry are still under discussion, [8,62,63] because the defect composition is very sensitive to the atmosphere and sample preparation conditions. [62,64,65] The defect chemistry model assumes formation of different point defects in the bismuth ferrite, namely: oxygen and bismuth vacancies (see details in Section 4, Supporting Information).…”

Section: Structural and Chemical Characterizationmentioning

confidence: 99%

“…Based on the above chemical analysis of the surface, it can be proposed that the downward polarization can be screened by holes and positively charged oxygen vacancies ( ) O •• V , while negatively charged iron (V′′′ Fe ) and bismuth vacancies (V′′′ Bi ) participate in screening of the upward polarization (Figure 7a). Though the depolarization field can be partially reduced by the defect complexes with a dipole moment (defect dipoles), [6,60,61] their impact on the reduction of the depolarization field is seen to be minor because they have high activation energies for transport compared to the single charged defects. [63] The contribution of the charged defects to the dynamics of the polarization switching is dependent on the defect mobility.…”

Section: Monitoring Dynamics Of Charged Defects and Their Contributio...mentioning

confidence: 99%

Exploring Charged Defects in Ferroelectrics by the Switching Spectroscopy Piezoresponse Force Microscopy

et al. 2021

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information storage, [1,2] memristors based on tunneling, [3,4] energy storage devices, [5] etc. Tailoring the defect structure permits fine tuning of the functional properties of ferroelectrics. [6][7][8][9][10] The surfaces and interfaces are directly influenced by the nearby defects, and bulk properties are rendered by the defects via multiple mechanisms. [11,12] Up to date, the number of techniques allowing studies of defects with a high spatial resolution is limited, and they are mainly based on local monitoring of the crystalline structure or chemical composition. [13][14][15][16] Most of these local compositional methods like transmission electron microscopy, X-ray tomography, electron holography, etc. do not have a high enough sensitivity or need challenging sample preparation. [13] The optical method of second harmonic generation can be used to monitor the defect concentration and off-stoichiometry, [16] however it is limited in resolving the type of charged defects and yields only micrometer-scale spatial resolution. Thus, the novel experimental approaches allowing accurate measurement of the defect concentration and/or corresponded functional properties at the nanoscale are highly desirable.In ferroelectrics, charged defects affect polarization reversal as they directly participate in the screening of the depolarization electric field [8,[17][18][19][20] since they can become mobile Monitoring the charged defect concentration at the nanoscale is of critical importance for both the fundamental science and applications of ferroelectrics. However, up-to-date, high-resolution study methods for the investigation of structural defects, such as transmission electron microscopy, X-ray tomography, etc., are expensive and demand complicated sample preparation. With an example of the lanthanum-doped bismuth ferrite ceramics, a novel method is proposed based on the switching spectroscopy piezoresponse force microscopy (SSPFM) that allows probing the electric potential from buried subsurface charged defects in the ferroelectric materials with a nanometer-scale spatial resolution. When compared with the compositionsensitive methods, such as neutron diffraction, X-ray photoelectron spectroscopy, and local time-of-flight secondary ion mass spectrometry, the SSPFM sensitivity to the variation of the electric potential from the charged defects is shown to be equivalent to less than 0.3 at% of the defect concentration. Additionally, the possibility to locally evaluate dynamics of the polarization screening caused by the charged defects is demonstrated, which is of significant interest for further understanding defect-mediated processes in ferroelectrics.

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“…In theory this should also hold for ferroelectric superlattices that have compositional inversion symmetry [2][3][4]. However, in practice, electric polarization asymmetry, where one polarization state is preferred over another, or in other words, a built-in bias, is often seen in ferroelectric thin films and superlattices [5][6][7][8][9]. Many contributing factors have been suggested as sources of polarization asymmetry.…”

Section: Introductionmentioning

confidence: 99%

Controlling ferroelectric hysteresis offsets in PbTiO$_{3}$ based superlattices

Divilov,

Hsing,

Yusuf

et al. 2020

Preprint

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Ferroelectric materials are characterized by degenerate ground states with multiple polarization directions. In a ferroelectric capacitor this should manifest as equally favourable up and down polarization states. However, this ideal behavior is rarely observed in ferroelectric thin films and superlattice devices, which generally exhibit a built-in bias which favors one polarization state over the other. Often this polarization asymmetry can be attributed to the electrodes. In this study we examine bias in PbTiO3-based ferroelectric superlattices that is not due to the electrodes, but rather to the nature of the defects that form at the interfaces during growth. Using a combination of experiments and first-principles simulations, we are able to explain the sign of the observed built-in bias and its evolution with composition. Our insights allow us to design devices with zero built-in bias by controlling the composition and periodicity of the superlattices.

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Ferroelectric polarization and defect-dipole switching in an epitaxial (111) BiFeO3 thin film

Abstract: Articles you may be interested inChemical solution deposition derived (001)-oriented epitaxial BiFeO3 thin films with robust ferroelectric properties using stoichiometric precursors (invited)

Cited by 18 publications

References 33 publications

Carrier-Activated Polarization in Organometal Halide Perovskites

Carrier-Activated Polarization in Organometal Halide Perovskites

Exploring Charged Defects in Ferroelectrics by the Switching Spectroscopy Piezoresponse Force Microscopy

Controlling ferroelectric hysteresis offsets in PbTiO$_{3}$ based superlattices

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