Enhancement of the anisotropic photocurrent in ferroelectric oxides by strain gradients

Chu, Kanghyun; Jang, Byung-Kweon; Sung, Ji Ho; Shin, Yoon Ah; Song, Kyung; Lee, Jun Young; Woo, Chang-Su; Kim, Seung Jin; Choi, Si‐Young; Koo, Tae Yeong; Kim, Yong Hyun; Oh, Seogil; Jo, Moon‐Ho; Yang, Chan−Ho

doi:10.1038/nnano.2015.191

Cited by 143 publications

(78 citation statements)

References 46 publications

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“…[113] This effect reportedly affects the ferroelectric properties of materials, such as their critical thickness, the electrical transport of the domain wall, and the mechanical switching of polarization. [115][116][117] It consequently also affects the observed PFM response by unpredictably changing the material properties.…”

Section: Electrochemical Strainmentioning

confidence: 99%

Non-piezoelectric effects in piezoresponse force microscopy

Seol¹,

Kim²,

Kim³

2017

Current Applied Physics

131

114

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Piezoresponse force microscopy (PFM) has been used extensively for exploring nanoscale ferro/piezoelectric phenomena over the past two decades. The imaging mechanism of PFM is based on the detection of the electromechanical (EM) response induced by the inverse piezoelectric effect through the cantilever dynamics of an atomic force microscopy. However, several non-piezoelectric effects can induce additional contributions to the EM response, which often lead to a misinterpretation of the measured PFM response. This review aims to summarize the non-piezoelectric origins of the EM response that impair the interpretation of PFM measurements. We primarily discuss two major non-piezoelectric origins, namely, the electrostatic effect and electrochemical strain. Several approaches for differentiating the ferroelectric contribution from the EM response are also discussed. The review suggests a fundamental guideline for the proper utilization of the PFM technique, as well as for achieving a reasonable interpretation of observed PFM responses.

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Section: Electrochemical Strainmentioning

confidence: 99%

Non-piezoelectric effects in piezoresponse force microscopy

Seol¹,

Kim²,

Kim³

2017

Current Applied Physics

131

114

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“…These should involve at least the lead-free piezoelectric elements containing no piezoelectric materials working through flexoelectric couplings2223242526272829, perovskite based photovoltaics/photocatalysis3031, flexible devices32 and gradient functional materials33.…”

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confidence: 99%

“…Nevertheless, the above proposals are based on either the theoretical simulations16242527 or mechanical bending of nanofibers/cantilevers17181920 or limited information near the domain walls of ferroelectrics3031. Although mechanical buckling seems an effective way to pattern stretchable semiconductor and ferroelectric nanoribbons3234, the corresponding attainable strain gradients are relatively lower and failure tends to occur when manipulating brittle ceramics such as ferroelectrics.…”

mentioning

confidence: 99%

Giant linear strain gradient with extremely low elastic energy in a perovskite nanostructure array

et al. 2017

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Although elastic strains, particularly inhomogeneous strains, are able to tune, enhance or create novel properties of some nanoscale functional materials, potential devices dominated by inhomogeneous strains have not been achieved so far. Here we report a fabrication of inhomogeneous strains with a linear gradient as giant as 106 per metre, featuring an extremely lower elastic energy cost compared with a uniformly strained state. The present strain gradient, resulting from the disclinations in the BiFeO3 nanostructures array grown on LaAlO3 substrates via a high deposition flux, induces a polarization of several microcoulomb per square centimetre. It leads to a large built-in electric field of several megavoltage per metre, and gives rise to a large enhancement of solar absorption. Our results indicate that it is possible to build up large-scale strain-dominated nanostructures with exotic properties, which in turn could be useful in the development of novel devices for electromechanical and photoelectric applications.

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“…The value of approximately 0.1 Å in the lower part is similar to the value provided in previous reports for BFO thin films24, while the value of approximately 0.7 Å in the upper part is the largest value obtained so far. The large value that represents the cation displacement in the upper region can be attributed to the flexoelectric effect arising from the strain gradient near the t c [refs 25,26] or small tilt effect due to sample bending in the upper part as compared to the lower part. It should be noted that when a thin film is subjected to strain gradient that varies in different localities, the local crystal orientation in the sample can even also accordingly change as shown in the FFT patterns for the lower and upper parts of BiFeO 3 (Fig.…”

Section: Resultsmentioning

confidence: 99%

Depth resolved lattice-charge coupling in epitaxial BiFeO3 thin film

Lee

Kwak

et al. 2016

Sci Rep

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For epitaxial films, a critical thickness (tc) can create a phenomenological interface between a strained bottom layer and a relaxed top layer. Here, we present an experimental report of how the tc in BiFeO3 thin films acts as a boundary to determine the crystalline phase, ferroelectricity, and piezoelectricity in 60 nm thick BiFeO3/SrRuO3/SrTiO3 substrate. We found larger Fe cation displacement of the relaxed layer than that of strained layer. In the time-resolved X-ray microdiffraction analyses, the piezoelectric response of the BiFeO3 film was resolved into a strained layer with an extremely low piezoelectric coefficient of 2.4 pm/V and a relaxed layer with a piezoelectric coefficient of 32 pm/V. The difference in the Fe displacements between the strained and relaxed layers is in good agreement with the differences in the piezoelectric coefficient due to the electromechanical coupling.

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Enhancement of the anisotropic photocurrent in ferroelectric oxides by strain gradients

Cited by 143 publications

References 46 publications

Non-piezoelectric effects in piezoresponse force microscopy

Non-piezoelectric effects in piezoresponse force microscopy

Giant linear strain gradient with extremely low elastic energy in a perovskite nanostructure array

Depth resolved lattice-charge coupling in epitaxial BiFeO3 thin film

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