For Publishers
DiscoveryMetadataPeer reviewHostingPublishing
For Researchers
JoinPublishReviewCollect
Register
Blog
About
Search
Advanced search
My ScienceOpen
Search
For Publishers
For Researchers
Blog
About
25
views
66
references
 Top references
cited by
5
    
0 reviews
 Review
0
comments
 Comment
0
recommends
+1 Recommend
0 collections
    0
    shares
      105
      similar
       All similar
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Concurrent bandgap narrowing and polarization enhancement in epitaxial ferroelectric nanofilms

      research-article

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Perovskite-type ferroelectric (FE) crystals are wide bandgap materials with technologically valuable optical and photoelectric properties. Here, versatile engineering of electronic transitions is demonstrated in FE nanofilms of KTaO 3, KNbO 3 (KNO), and NaNbO 3 (NNO) with a thickness of 10–30 unit cells. Control of the bandgap is achieved using heteroepitaxial growth of new structural phases on SrTiO 3 (001) substrates. Compared to bulk crystals, anomalous bandgap narrowing is obtained in the FE state of KNO and NNO films. This effect opposes polarization-induced bandgap widening, which is typically found for FE materials. Transmission electron microscopy and spectroscopic ellipsometry measurements indicate that the formation of higher-symmetry structural phases of KNO and NNO produces the desirable red shift of the absorption spectrum towards visible light, while simultaneously stabilizing robust FE order. Tuning of optical properties in FE films is of interest for nanoscale photonic and optoelectronic devices.

          Related collections

          Most cited references66

          • Record: found
          • Abstract: found
          • Article: not found

          Lead-free piezoceramics.

          Yasuyoshi Saito, Hisaaki Takao, Toshihiko Tani … (2004)
          Lead has recently been expelled from many commercial applications and materials (for example, from solder, glass and pottery glaze) owing to concerns regarding its toxicity. Lead zirconium titanate (PZT) ceramics are high-performance piezoelectric materials, which are widely used in sensors, actuators and other electronic devices; they contain more than 60 weight per cent lead. Although there has been a concerted effort to develop lead-free piezoelectric ceramics, no effective alternative to PZT has yet been found. Here we report a lead-free piezoelectric ceramic with an electric-field-induced strain comparable to typical actuator-grade PZT. We achieved this through the combination of the discovery of a morphotropic phase boundary in an alkaline niobate-based perovskite solid solution, and the development of a processing route leading to highly textured polycrystals. The ceramic exhibits a piezoelectric constant d33 (the induced charge per unit force applied in the same direction) of above 300 picocoulombs per newton (pC N(-1)), and texturing the material leads to a peak d33 of 416 pC N(-1). The textured material also exhibits temperature-independent field-induced strain characteristics.
          Article 0 comments Cited 789 times – based on 0 reviews     Review now
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Above-bandgap voltages from ferroelectric photovoltaic devices.

            S. Yang, J Seidel, S. Byrnes … (2010)
            In conventional solid-state photovoltaics, electron-hole pairs are created by light absorption in a semiconductor and separated by the electric field spaning a micrometre-thick depletion region. The maximum voltage these devices can produce is equal to the semiconductor electronic bandgap. Here, we report the discovery of a fundamentally different mechanism for photovoltaic charge separation, which operates over a distance of 1-2 nm and produces voltages that are significantly higher than the bandgap. The separation happens at previously unobserved nanoscale steps of the electrostatic potential that naturally occur at ferroelectric domain walls in the complex oxide BiFeO(3). Electric-field control over domain structure allows the photovoltaic effect to be reversed in polarity or turned off. This new degree of control, and the high voltages produced, may find application in optoelectronic devices.
            Article 0 comments Cited 455 times – based on 0 reviews     Review now
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Switchable ferroelectric diode and photovoltaic effect in BiFeO3.

              T. Choi, S. Lee, Y. Choi … (2009)
              Unidirectional electric current flow, such as that found in a diode, is essential for modern electronics. It usually occurs at asymmetric interfaces such as p-n junctions or metal/semiconductor interfaces with Schottky barriers. We report on a diode effect associated with the direction of bulk electric polarization in BiFeO3: a ferroelectric with a small optical gap edge of approximately 2.2 electron volts. We found that bulk electric conduction in ferroelectric monodomain BiFeO3 crystals is highly nonlinear and unidirectional. This diode effect switches its direction when the electric polarization is flipped by an external voltage. A substantial visible-light photovoltaic effect is observed in BiFeO3 diode structures. These results should improve understanding of charge conduction mechanisms in leaky ferroelectrics and advance the design of switchable devices combining ferroelectric, electronic, and optical functionalities.
              Article 0 comments Cited 449 times – based on 0 reviews     Review now
                Bookmark
                All references

                Author and article information

                Journal
                Journal ID (nlm-ta): Sci Technol Adv Mater
                Journal ID (iso-abbrev): Sci Technol Adv Mater
                Journal ID (publisher-id): TSTA
                Title: Science and Technology of Advanced Materials
                Publisher: Taylor & Francis
                ISSN (Print): 1468-6996
                ISSN (Electronic): 1878-5514
                Publication date Collection: April 2015
                Publication date (Electronic): 8 April 2015
                Volume: 16
                Issue: 2
                Electronic Location Identifier: 026002
                Affiliations
                [1 ]Microelectronics and Materials Physics Laboratories, University of Oulu, PO Box 4500, FI-90014 Oulun Yliopisto, Finland
                [2 ]NanoSpin, Department of Applied Physics, Aalto University School of Science, PO Box 15100, FI-00076 Aalto, Finland
                [3 ]Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
                [4 ]Ioffe Physical-Technical Institute RAS, 194021 St. Petersburg, Russia
                Author notes
                Article
                Publisher ID: TSTA11661274
                DOI: 10.1088/1468-6996/16/2/026002
                PMC ID: 5036465
                SO-VID: 283bef12-46e3-4d92-9ada-becccabb04c7
                Copyright © © 2015 National Institute for Materials Science
                License:

                Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

                History
                Date received : Received on December 01, 2014
                Date accepted : Accepted on March 04, 2015
                Funding
                Funded by: Grant Agency of Czech Republic
                Award ID: P108/12/1941
                Funded by: Suomen Akatemia 10.13039/501100002341
                Award ID: 260361
                Award ID: 264961
                Funded by: European Research Council 10.13039/501100000781
                Award ID: 307502
                Funded by: Ministry of Education and Science of Russia
                Award ID: 8516
                Categories
                Subject: Papers

                Keywords: epitaxial growth,ferroelectric nanofilms,optical properties
                Data availability:
                Keywords: epitaxial growth, ferroelectric nanofilms, optical properties

                Comments

                Comment on this article

                scite_

                Similar content105

                See all similar

                Cited by5

                See all cited by

                Most referenced authors1,431

                See all reference authors