1
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Structural, electronic, optical and mechanical properties of oxide-based perovskite ABO3 (A = Cu, Nd and B = Sn, Sc): A DFT study. J SOLID STATE CHEM 2023. [DOI: 10.1016/j.jssc.2022.123650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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2
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Filip MR, Qiu DY, Del Ben M, Neaton JB. Screening of Excitons by Organic Cations in Quasi-Two-Dimensional Organic-Inorganic Lead-Halide Perovskites. NANO LETTERS 2022; 22:4870-4878. [PMID: 35679538 PMCID: PMC9228398 DOI: 10.1021/acs.nanolett.2c01306] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Interlayer organic cations in quasi-two-dimensional halide perovskites are a versatile tuning vehicle for the optoelectronic properties of these complex systems, but chemical intuition for this design route is yet to be established. Here, we use density functional theory, the GW approximation, and the Bethe-Salpeter equation approach to understand the contribution of the organic cation to the quasiparticle band gap and exciton binding energy of layered perovskites. We show that organic cations in quasi-two-dimensional perovskites contribute significantly to the dielectric screening in these systems, countering quantum confinement effects on the quasiparticle band gap and the exciton binding energy. Using a simple electrostatics model inspired by parallel-plate capacitors, we decouple the organic cation and inorganic layer contributions to the effective dielectric constants and show that dielectric properties of layered perovskites are broadly tunable via the interlayer cation, providing a direct means of tuning photophysical properties for a variety of applications.
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Affiliation(s)
- Marina R. Filip
- Department
of Physics, University of Oxford, Clarendon
Laboratory, Oxford OX1 3PU, United Kingdom
| | - Diana Y. Qiu
- School
of Engineering and Applied Science, Yale
University, New Haven, Connecticut 06511, United States
| | - Mauro Del Ben
- Computational
Science Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Jeffrey B. Neaton
- Department
of Physics, University of California, Berkeley, California 94720, United States
- Materials
Science Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Kavli
Energy Nano Sciences Institute at Berkeley, Berkeley, California 94720, United States
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3
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Rusevich LL, Tyunina M, Kotomin EA, Nepomniashchaia N, Dejneka A. The electronic properties of SrTiO 3-δ with oxygen vacancies or substitutions. Sci Rep 2021; 11:23341. [PMID: 34857848 PMCID: PMC8639995 DOI: 10.1038/s41598-021-02751-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 11/17/2021] [Indexed: 12/14/2022] Open
Abstract
The electronic properties, including bandgap and conductivity, are critical for nearly all applications of multifunctional perovskite oxide ferroelectrics. Here we analysed possibility to induce semiconductor behaviour in these materials, which are basically insulators, by replacement of several percent of oxygen atoms with nitrogen, hydrogen, or vacancies. We explored this approach for one of the best studied members of the large family of ABO3 perovskite ferroelectrics - strontium titanate (SrTiO3). The atomic and electronic structure of defects were theoretically investigated using the large-scale first-principles calculations for both bulk crystal and thin films. The results of calculations were experimentally verified by studies of the optical properties at photon energies from 25 meV to 8.8 eV for in-situ prepared thin films. It was demonstrated that substitutions and vacancies prefer locations at surfaces or phase boundaries over those inside crystallites. At the same time, local states in the bandgap can be produced by vacancies located both inside the crystals and at the surface, but by nitrogen substitution only inside crystals. Wide-bandgap insulator phases were evidenced for all defects. Compared to pure SrTiO3 films, bandgap widening due to defects was theoretically predicted and experimentally detected.
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Affiliation(s)
- L L Rusevich
- Institute of Solid State Physics, University of Latvia, Kengaraga Str. 8, Riga, 1063, Latvia.
| | - M Tyunina
- Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, P. O. Box 4500, 90014, Oulu, Finland.
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221, Prague, Czech Republic.
| | - E A Kotomin
- Institute of Solid State Physics, University of Latvia, Kengaraga Str. 8, Riga, 1063, Latvia
- Max Planck Institute for Solid State Research, Heisenberg Str. 1, 70569, Stuttgart, Germany
| | - N Nepomniashchaia
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221, Prague, Czech Republic
| | - A Dejneka
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221, Prague, Czech Republic
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4
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Tyunina M, Pacherova O, Nepomniashchaia N, Vetokhina V, Cichon S, Kocourek T, Dejneka A. In situ anion-doped epitaxial strontium titanate films. Phys Chem Chem Phys 2020; 22:24796-24800. [PMID: 33107506 DOI: 10.1039/d0cp03644g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Misfit strains arising from a film-substrate mismatch can induce novel phases and properties in the epitaxial films of perovskite oxides. Here we employ yet another effect, namely, strain-assisted formation of oxygen vacancies. We demonstrate the misfit-promoted presence of oxygen vacancies and related substitutional incorporation of anion dopants in the epitaxial films of archetypal perovskite oxide SrTiO3. Both the oxygen vacancies and hydrogen or nitrogen dopants are introduced in situ during the pulsed-laser deposition of the films using compressive substrates. The films exhibit peculiar chemical expansion and optical properties, which are consistent with substitutional anion doping.
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Affiliation(s)
- M Tyunina
- Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, P. O. Box 4500, FI-90014, Finland.
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5
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Song C, Li X, Jiang Y, Wang X, Yao J, Meng S, Zhang J. Real-Space Imaging of Orbital Selectivity on SrTiO 3(001) Surface. ACS APPLIED MATERIALS & INTERFACES 2019; 11:37279-37284. [PMID: 31529959 DOI: 10.1021/acsami.9b11724] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Real-space access of the orbital degree of freedom in complex oxides is still challenging due to intricate electronic hybridization. Here, we report a direct observation of reproducible orbital-selective tunneling on a novel SrTiO3(001) surface by scanning tunneling microscopy. The electronic structures reversibly switch between two different sets of symmetries depending on the sample bias, which is accompanied by a remarkable change in energy-dependent spectroscopy data. Tunneling spectrum combined with density functional theory calculations elucidates that symmetry-breaking at the surface determines the crystal-splitting field of eg/t2g orbitals with a strong in-plane anisotropy so that electrons alternatingly fill eg and t2g orbitals during the imaging process with different biases. This surface superstructure provides a new strategy toward understanding orbital textures and orbital selectivity in complex oxides.
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Affiliation(s)
- Chuangye Song
- Department of Physics , Beijing Normal University , Beijing 100875 , China
| | - Xuanyi Li
- Institute of Physics , Chinese Academic of Science , Beijing 100190 , China
- School of Physics , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Ying Jiang
- International Center for Quantum Materials, School of Physics , Peking University , Beijing 100871 , China
| | - Xi Wang
- Key Laboratory of Luminescence and Optical Information, Ministry of Education, Department of Physics, School of Science , Beijing Jiaotong University , Beijing 100044 , China
- Chemistry and Chemical Engineering Guangdong Laboratory , Shantou 515031 , China
| | - Jiannian Yao
- Chemistry and Chemical Engineering Guangdong Laboratory , Shantou 515031 , China
- Key Laboratory of Photochemistry, Institute of Chemistry , Chinese Academy of Science , Beijing 100190 , China
| | - Sheng Meng
- Institute of Physics , Chinese Academic of Science , Beijing 100190 , China
- School of Physics , University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Jinxing Zhang
- Department of Physics , Beijing Normal University , Beijing 100875 , China
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6
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Makin RA, York K, Durbin SM, Senabulya N, Mathis J, Clarke R, Feldberg N, Miska P, Jones CM, Deng Z, Williams L, Kioupakis E, Reeves RJ. Alloy-Free Band Gap Tuning across the Visible Spectrum. PHYSICAL REVIEW LETTERS 2019; 122:256403. [PMID: 31347908 DOI: 10.1103/physrevlett.122.256403] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 12/16/2018] [Indexed: 06/10/2023]
Abstract
We present evidence, from theory and experiment, that ZnSnN_{2} and MgSnN_{2} can be used to match the band gap of InGaN without alloying-by exploiting cation disorder in a controlled fashion. We base this on the determination of S, the long-range order parameter of the cation sublattice, for a series of epitaxial thin films of ZnSnN_{2} and MgSnN_{2} using three different techniques: x-ray diffraction, Raman spectroscopy, and in situ electron diffraction. We observe a linear relationship between S^{2} and the optical band gap of both ZnSnN_{2} (1.12-1.98 eV) and MgSnN_{2} (1.87-3.43 eV). The results clearly demonstrate the correlation between controlled heterovalent cation ordering and the optical band gap, which applies to a broad group of emerging ternary heterovalent compounds and has implications for similar trends in other material properties besides the band gap.
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Affiliation(s)
- Robert A Makin
- Department of Electrical and Computer Engineering, Western Michigan University, Kalamazoo, Michigan 49008, USA
| | - Krystal York
- Department of Electrical and Computer Engineering, Western Michigan University, Kalamazoo, Michigan 49008, USA
| | - Steven M Durbin
- Department of Electrical and Computer Engineering, Western Michigan University, Kalamazoo, Michigan 49008, USA
| | - Nancy Senabulya
- Applied Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - James Mathis
- Applied Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Roy Clarke
- Applied Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | | | - Patrice Miska
- Université de Lorraine, CNRS, IJL, F-54000 Nancy, France
| | - Christina M Jones
- Applied Physics, University of Michigan, Ann Arbor, Michigan 48109, USA and Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Zihao Deng
- Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Logan Williams
- Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Emmanouil Kioupakis
- Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Roger J Reeves
- School of Physical and Chemical Sciences, University of Canterbury, Christchurch 8140, New Zealand
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7
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Tyunina M, Chvostova D, Dejneka A. Optical revelation of defects in epitaxial barium titanate films. Phys Chem Chem Phys 2019; 21:7874-7878. [PMID: 30916091 DOI: 10.1039/c9cp00923j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Allying epitaxial strain and synthesis conditions allows for the introduction of specific point defects in perovskite oxide films. In ferroelectric films, such defects lead to essential polar and electronic properties, which can enable advanced applications. Here, to elucidate the nature of the defects, optical constants are investigated in the spectral range of 0.7-8.8 eV in epitaxial ferroelectric BaTiO3 films, which are synthesized under different conditions. It is demonstrated that oxygen-vacancy-related defects are responsible for a peculiar transition below the bandgap at ∼2.7-2.9 eV and significant blueshifts of ∼0.3-0.4 eV of the gap and the main interband transitions. These observations suggest that the defects are dipolar complexes comprising titanium cations and oxygen vacancies (Ti3+-VO).
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Affiliation(s)
- M Tyunina
- Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, P. O. Box 4500, FI-90014, Finland.
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8
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Huang Z, Renshaw Wang X, Rusydi A, Chen J, Yang H, Venkatesan T. Interface Engineering and Emergent Phenomena in Oxide Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1802439. [PMID: 30133012 DOI: 10.1002/adma.201802439] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 07/06/2018] [Indexed: 06/08/2023]
Abstract
Complex oxide interfaces have mesmerized the scientific community in the last decade due to the possibility of creating tunable novel multifunctionalities, which are possible owing to the strong interaction among charge, spin, orbital, and structural degrees of freedom. Artificial interfacial modifications, which include defects, formal polarization, structural symmetry breaking, and interlayer interaction, have led to novel properties in various complex oxide heterostructures. These emergent phenomena not only serve as a platform for investigating strong electronic correlations in low-dimensional systems but also provide potentials for exploring next-generation electronic devices with high functionality. Herein, some recently developed strategies in engineering functional oxide interfaces and their emergent properties are reviewed.
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Affiliation(s)
- Zhen Huang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Xiao Renshaw Wang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Andrivo Rusydi
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Jingsheng Chen
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Hyunsoo Yang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Thirumalai Venkatesan
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
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9
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Gao Q, Chen H, Li K, Liu Q. Band Gap Engineering and Room-Temperature Ferromagnetism by Oxygen Vacancies in SrSnO 3 Epitaxial Films. ACS APPLIED MATERIALS & INTERFACES 2018; 10:27503-27509. [PMID: 30001107 DOI: 10.1021/acsami.8b08508] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Perovskite SrSnO3 (SSO) thin films were epitaxially grown on LaAlO3 (001) substrates by pulsed laser deposition at various oxygen pressures. X-ray diffraction was carried out to characterize the microstructure of the films, and the results showed that the unit-cell volume of the films increased gradually with lowering the growth oxygen pressures while remaining the perovskite structure. X-ray photoelectron spectroscopy results indicated that oxygen vacancies (OVs) existed in SSO thin films. Optical property measurements showed that all samples have a transmittance of more than 75% in the visible and near-infrared wavelength region. Furthermore, the band gaps of SSO films were found to increase from 4.56 to 5.21 eV with the decrease of deposition oxygen pressures calculated by linear fitting absorption edges of optical transmittance. In order to further ascertain the effect of OVs on band gaps of SSO films, the as-deposited 10 Pa film was annealed at 10-4 Pa oxygen pressures and the band gap was found to increase by more than 1 eV. Density functional theory was used to explain the effects of OVs on band gaps and the ferromagnetism of SSO films, and the results suggested that an impurity energy level of OVs appeared near the Fermi level, causing the widening of the band gaps, which is consistent with our experimental results. Meanwhile, the room-temperature ferromagnetism was observed in the SSO films, and saturation magnetization increased gradually from 4.46 to 7.69 emu/cm3 with decreasing the growth oxygen pressures.
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Affiliation(s)
- Qiang Gao
- School of Physics and Electronic Information , Huaibei Normal University , Huaibei 235000 , P. R. China
| | - Hengli Chen
- School of Material Science and Engineering , Hebei University of Technology , Tianjin 300130 , China
| | - Kaifeng Li
- School of Physics and Electronic Information , Huaibei Normal University , Huaibei 235000 , P. R. China
| | - Qinzhuang Liu
- School of Physics and Electronic Information , Huaibei Normal University , Huaibei 235000 , P. R. China
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10
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Grabill LP, Berger RF. Calibrating the Extended Hückel Method to Quantitatively Screen the Electronic Properties of Materials. Sci Rep 2018; 8:10530. [PMID: 30002480 PMCID: PMC6043563 DOI: 10.1038/s41598-018-28864-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 07/02/2018] [Indexed: 11/19/2022] Open
Abstract
The extended Hückel (eH) tight-binding method has historically been prized for its computational ease and intuitive chemical clarity. However, its lack of quantitative predictiveness has prevented the eH method from being used as a tool for rapidly screening materials for desired electronic properties. In this work, we demonstrate that when eH input parameters are calibrated using density functional theory (DFT) calculations of carefully chosen sets of simple crystals, the eH parameters retain most of their quantitative accuracy when transferred to more complex, structurally related phases. Using solar-energy-relevant semiconductors and insulators in the Sr–Ti–O family as a case study, we show that calibrated eH parameters can match the features of DFT band structures within about two tenths of an eV, at a tiny fraction of the computational cost of DFT.
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Affiliation(s)
- Linda P Grabill
- Department of Chemistry, Western Washington University, Bellingham, WA, USA
| | - Robert F Berger
- Department of Chemistry, Western Washington University, Bellingham, WA, USA.
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11
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Wang J, Huang H, He W, Zhang Q, Yang D, Zhang Y, Liang R, Wang C, Ma X, Gu L, Chen L, Nan CW, Zhang J. Nanoscale Bandgap Tuning across an Inhomogeneous Ferroelectric Interface. ACS APPLIED MATERIALS & INTERFACES 2017; 9:24704-24710. [PMID: 28686410 DOI: 10.1021/acsami.7b05138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report nanoscale bandgap engineering via a local strain across the inhomogeneous ferroelectric interface, which is controlled by the visible-light-excited probe voltage. Switchable photovoltaic effects and the spectral response of the photocurrent were explored to illustrate the reversible bandgap variation (∼0.3 eV). This local-strain-engineered bandgap has been further revealed by in situ probe-voltage-assisted valence electron energy-loss spectroscopy (EELS). Phase-field simulations and first-principle calculations were also employed for illustration of the large local strain and the bandgap variation in ferroelectric perovskite oxides. This reversible bandgap tuning in complex oxides demonstrates a framework for the understanding of the optically related behaviors (photovoltaic, photoemission, and photocatalyst effects) affected by order parameters such as charge, orbital, and lattice parameters.
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Affiliation(s)
- Jing Wang
- Department of Physics, Beijing Normal University , 100875 Beijing, China
| | - Houbing Huang
- Department of Physics, University of Science and Technology Beijing , 100083 Beijing, China
| | - Wangqiang He
- Department of Physics, University of Science and Technology Beijing , 100083 Beijing, China
| | - Qinghua Zhang
- School of Materials Science and Engineering, Tsinghua University , 100084 Beijing, China
| | - Danni Yang
- Department of Physics, Beijing Normal University , 100875 Beijing, China
| | - Yuelin Zhang
- Department of Physics, Beijing Normal University , 100875 Beijing, China
| | - Renrong Liang
- Tsinghua National Laboratory for Information Science and Technology, Institute of Microelectronics, Tsinghua University , 100084 Beijing, China
| | - Chuanshou Wang
- Department of Physics, Beijing Normal University , 100875 Beijing, China
| | - Xingqiao Ma
- Department of Physics, University of Science and Technology Beijing , 100083 Beijing, China
| | - Lin Gu
- Institute of Physics, Chinese Academy of Science , 100190 Beijing, China
| | - Longqing Chen
- Department of Materials Science and Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Ce-Wen Nan
- School of Materials Science and Engineering, Tsinghua University , 100084 Beijing, China
| | - Jinxing Zhang
- Department of Physics, Beijing Normal University , 100875 Beijing, China
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12
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Chen H, Millis A. Design of new Mott multiferroics via complete charge transfer: promising candidates for bulk photovoltaics. Sci Rep 2017; 7:6142. [PMID: 28733597 PMCID: PMC5522466 DOI: 10.1038/s41598-017-06396-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 06/09/2017] [Indexed: 11/10/2022] Open
Abstract
Optimal materials to induce bulk photovoltaic effects should lack inversion symmetry and have an optical gap matching the energies of visible radiation. Ferroelectric perovskite oxides such as BaTiO3 and PbTiO3 exhibit substantial polarization and stability, but have the disadvantage of excessively large band gaps. We use both density functional theory and dynamical mean field theory calculations to design a new class of Mott multiferroics–double perovskite oxides A2VFeO6 (A = Ba, Pb, etc). While neither perovskite AVO3 nor AFeO3 is ferroelectric, in the double perovskite A2VFeO6 a ‘complete’ charge transfer from V to Fe leads to a non-bulk-like charge configuration–an empty V-d shell and a half-filled Fe-d shell, giving rise to a polarization comparable to that of ferroelectric ATiO3. Different from nonmagnetic ATiO3, the new double perovskite oxides have an antiferromagnetic ground state and around room temperatures, are paramagnetic Mott insulators. Most importantly, the V d0 state significantly reduces the band gap of A2VFeO6, making it smaller than that of ATiO3 and BiFeO3 and rendering the new multiferroics a promising candidate to induce bulk photovoltaic effects.
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Affiliation(s)
- Hanghui Chen
- NYU-ECNU Institute of Physics, NYU Shanghai, Shanghai, 200062, China. .,Department of Physics, New York University, New York, NY, 10002, USA.
| | - Andrew Millis
- Department of Physics, Columbia University, New York, NY, 10027, USA
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13
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Murali B, Yengel E, Peng W, Chen Z, Alias MS, Alarousu E, Ooi BS, Burlakov V, Goriely A, Eddaoudi M, Bakr OM, Mohammed OF. Temperature-Induced Lattice Relaxation of Perovskite Crystal Enhances Optoelectronic Properties and Solar Cell Performance. J Phys Chem Lett 2017; 8:137-143. [PMID: 27966364 DOI: 10.1021/acs.jpclett.6b02684] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Hybrid organic-inorganic perovskite crystals have recently become one of the most important classes of photoactive materials in the solar cell and optoelectronic communities. Albeit improvements have focused on state-of-the-art technology including various fabrication methods, device architectures, and surface passivation, progress is yet to be made in understanding the actual operational temperature on the electronic properties and the device performances. Therefore, the substantial effect of temperature on the optoelectronic properties, charge separation, charge recombination dynamics, and photoconversion efficiency are explored. The results clearly demonstrated a significant enhancement in the carrier mobility, photocurrent, charge carrier lifetime, and solar cell performance in the 60 ± 5 °C temperature range. In this temperature range, perovskite crystal exhibits a highly symmetrical relaxed cubic structure with well-aligned domains that are perpendicular to a principal axis, thereby remarkably improving the device operation. This finding provides a new key variable component and paves the way toward using perovskite crystals in highly efficient photovoltaic cells.
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Affiliation(s)
- Banavoth Murali
- King Abdullah University of Science and Technology , KAUST Solar Center, Division of Physical Sciences and Engineering, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Emre Yengel
- King Abdullah University of Science and Technology , KAUST Solar Center, Division of Physical Sciences and Engineering, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Wei Peng
- King Abdullah University of Science and Technology , KAUST Solar Center, Division of Physical Sciences and Engineering, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Zhijie Chen
- King Abdullah University of Science and Technology , Functional Materials Design, Discovery and Development Research Group, Advanced Membranes and Porous Materials Center, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Mohd S Alias
- King Abdullah University of Science and Technology , Photonics Laboratory, Computer, Electrical and Mathematical Sciences and Engineering Division, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Erkki Alarousu
- King Abdullah University of Science and Technology , KAUST Solar Center, Division of Physical Sciences and Engineering, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Boon S Ooi
- King Abdullah University of Science and Technology , Photonics Laboratory, Computer, Electrical and Mathematical Sciences and Engineering Division, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Victor Burlakov
- Mathematical Institute, University of Oxford , Woodstock Road, Oxford OX2 6GG, United Kingdom
| | - Alain Goriely
- Mathematical Institute, University of Oxford , Woodstock Road, Oxford OX2 6GG, United Kingdom
| | - Mohamed Eddaoudi
- King Abdullah University of Science and Technology , Functional Materials Design, Discovery and Development Research Group, Advanced Membranes and Porous Materials Center, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Osman M Bakr
- King Abdullah University of Science and Technology , KAUST Solar Center, Division of Physical Sciences and Engineering, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Omar F Mohammed
- King Abdullah University of Science and Technology , KAUST Solar Center, Division of Physical Sciences and Engineering, Thuwal 23955-6900, Kingdom of Saudi Arabia
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14
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Ma X, Wu X, Wang Y, Dai Y. Schottky barrier and band edge engineering via the interfacial structure and strain for the Pt/TiO2 heterostructure. Phys Chem Chem Phys 2017; 19:18750-18756. [DOI: 10.1039/c7cp03453a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Schottky barrier of the Pt/TiO2 interface depends strongly on both the interfacial stain and structure.
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Affiliation(s)
- Xiangchao Ma
- School of Physics and Optoelectronic Engineering
- Xidian University
- Xi'an
- China
| | - Xin Wu
- School of Physics and Optoelectronic Engineering
- Xidian University
- Xi'an
- China
| | - Yucheng Wang
- School of Physics and Optoelectronic Engineering
- Xidian University
- Xi'an
- China
| | - Ying Dai
- School of Physics
- State Key Laboratory of Crystal Materials
- Shandong University
- Jinan 250100
- China
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15
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Han K, Palina N, Zeng SW, Huang Z, Li CJ, Zhou WX, Wan DY, Zhang LC, Chi X, Guo R, Chen JS, Venkatesan T, Rusydi A, Ariando A. Controlling Kondo-like Scattering at the SrTiO3-based Interfaces. Sci Rep 2016; 6:25455. [PMID: 27147407 PMCID: PMC4857089 DOI: 10.1038/srep25455] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 04/13/2016] [Indexed: 11/08/2022] Open
Abstract
The observation of magnetic interaction at the interface between nonmagnetic oxides has attracted much attention in recent years. In this report, we show that the Kondo-like scattering at the SrTiO3-based conducting interface is enhanced by increasing the lattice mismatch and growth oxygen pressure PO2. For the 26-unit-cell LaAlO3/SrTiO3 (LAO/STO) interface with lattice mismatch being 3.0%, the Kondo-like scattering is observed when PO2 is beyond 1 mTorr. By contrast, when the lattice mismatch is reduced to 1.0% at the (La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 (LSAT/STO) interface, the metallic state is always preserved up to PO2 of 100 mTorr. The data from Hall measurement and X-ray absorption near edge structure (XANES) spectroscopy reveal that the larger amount of localized Ti(3+) ions are formed at the LAO/STO interface compared to LSAT/STO. Those localized Ti(3+) ions with unpaired electrons can be spin-polarized to scatter mobile electrons, responsible for the Kondo-like scattering observed at the LAO/STO interface.
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Affiliation(s)
- K. Han
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - N. Palina
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore
| | - S. W. Zeng
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Z. Huang
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
| | - C. J. Li
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
| | - W. X. Zhou
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - D.-Y. Wan
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - L. C. Zhang
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - X. Chi
- Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore
| | - R. Guo
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Material Science & Engineering, National University of Singapore, Singapore 117575, Singapore
| | - J. S. Chen
- Department of Material Science & Engineering, National University of Singapore, Singapore 117575, Singapore
| | - T. Venkatesan
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Department of Material Science & Engineering, National University of Singapore, Singapore 117575, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore 117456, Singapore
| | - A. Rusydi
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore
| | - A Ariando
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore 117456, Singapore
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16
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Chernova E, Pacherova O, Kocourek T, Jelinek M, Dejneka A, Tyunina M. Optical Properties of Ferroelectric Epitaxial K0.5Na0.5NbO3 Films in Visible to Ultraviolet Range. PLoS One 2016; 11:e0153261. [PMID: 27074042 PMCID: PMC4830626 DOI: 10.1371/journal.pone.0153261] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 03/26/2016] [Indexed: 12/02/2022] Open
Abstract
The complex index of refraction in the spectral range of 0.74 to 4.5 eV is studied by variable-angle spectroscopic ellipsometry in ferroelectric K0.5Na0.5NbO3 films. The 20-nm-thick cube-on-cube-type epitaxial films are grown on SrTiO3(001) and DyScO3(011) single-crystal substrates. The films are transparent and exhibit a significant difference between refractive indices Δn = 0.5 at photon energies below 3 eV. The energies of optical transitions are in the range of 3.15–4.30 eV and differ by 0.2–0.3 eV in these films. The observed behavior is discussed in terms of lattice strain and strain-induced ferroelectric polarization in epitaxial perovskite oxide films.
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Affiliation(s)
- E. Chernova
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221
- Czech Technical University, Technicka 2, Prague 6, Czech Republic, 166 27
- * E-mail: (EC); (MT)
| | - O. Pacherova
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221
| | - T. Kocourek
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221
| | - M. Jelinek
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221
| | - A. Dejneka
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221
| | - M. Tyunina
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, Czech Republic, 18221
- Microelectronics and Materials Physics Laboratories, University of Oulu, P. O. Box 4500, FI-90014 Oulun yliopisto, Finland
- * E-mail: (EC); (MT)
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17
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Sando D, Yang Y, Bousquet E, Carrétéro C, Garcia V, Fusil S, Dolfi D, Barthélémy A, Ghosez P, Bellaiche L, Bibes M. Large elasto-optic effect and reversible electrochromism in multiferroic BiFeO3. Nat Commun 2016; 7:10718. [PMID: 26923332 PMCID: PMC4773452 DOI: 10.1038/ncomms10718] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/14/2016] [Indexed: 11/09/2022] Open
Abstract
The control of optical fields is usually achieved through the electro-optic or acousto-optic effect in single-crystal ferroelectric or polar compounds such as LiNbO3 or quartz. In recent years, tremendous progress has been made in ferroelectric oxide thin film technology—a field which is now a strong driving force in areas such as electronics, spintronics and photovoltaics. Here, we apply epitaxial strain engineering to tune the optical response of BiFeO3 thin films, and find a very large variation of the optical index with strain, corresponding to an effective elasto-optic coefficient larger than that of quartz. We observe a concomitant strain-driven variation in light absorption—reminiscent of piezochromism—which we show can be manipulated by an electric field. This constitutes an electrochromic effect that is reversible, remanent and not driven by defects. These findings broaden the potential of multiferroics towards photonics and thin film acousto-optic devices, and suggest exciting device opportunities arising from the coupling of ferroic, piezoelectric and optical responses. Modern technology such as electronics and photovoltaics requires careful control of optical responses of electronic properties. Here, Sando et al. demonstrate a large variation of optical index and light absorption in multiferroic material BiFeO3 thin films, tunable by in-film strain or electric field.
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Affiliation(s)
- D Sando
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France
| | - Yurong Yang
- Department of Physics and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - E Bousquet
- Theoretical Materials Physics, Université de Liège, B-5, B-4000 Sart-Tilman, Belgium
| | - C Carrétéro
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France
| | - V Garcia
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France
| | - S Fusil
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France
| | - D Dolfi
- Thales Research and Technology France, 1 Avenue Augustin Fresnel, 91767 Palaiseau, France
| | - A Barthélémy
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France
| | - Ph Ghosez
- Theoretical Materials Physics, Université de Liège, B-5, B-4000 Sart-Tilman, Belgium
| | - L Bellaiche
- Department of Physics and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - M Bibes
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France
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18
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Ma X, Dai Y, Yu L, Huang B. Interface Schottky barrier engineering via strain in metal-semiconductor composites. NANOSCALE 2016; 8:1352-1359. [PMID: 26511292 DOI: 10.1039/c5nr05583k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The interfacial carrier transfer property, which is dominated by the interface Schottky barrier height (SBH), plays a crucial role in determining the performance of metal-semiconductor heterostructures in a variety of applications. Therefore, artificially controlling the interface SBH is of great importance for their industrial applications. As a model system, the Au/TiO2 (001) heterostructure is studied using first-principles calculations and the tight-binding method in the present study. Our investigation demonstrates that strain can be an effective way to decrease the interface SBH and that the n-type SBH can be more effectively decreased than the p-type SBH. Astonishingly, strain affects the interface SBH mainly by changing the intrinsic properties of Au and TiO2, whereas the interfacial potential alignment is almost independent of strain due to two opposite effects, which are induced by strain at the interfacial region. These observed trends can be understood on the basis of the general free-electron gas model of typical metals, the tight-binding theory and the crystal-field theory, which suggest that similar trends may be generalized for many other metal-semiconductor heterostructures. Given the commonness and tunability of strain in typical heterostructures, we anticipate that the tunability of the interface SBH with strain described here can provide an alternative effective way for realizing more efficient applications of relevant heterostructures.
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Affiliation(s)
- Xiangchao Ma
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, People's Republic of China.
| | - Ying Dai
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, People's Republic of China.
| | - Lin Yu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, People's Republic of China.
| | - Baibiao Huang
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, People's Republic of China.
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19
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Kobayashi S, Mizumukai Y, Ohnishi T, Shibata N, Ikuhara Y, Yamamoto T. High Electron Mobility of Nb-Doped SrTiO₃ Films Stemming from Rod-Type Sr Vacancy Clusters. ACS NANO 2015; 9:10769-10777. [PMID: 26487067 DOI: 10.1021/acsnano.5b05720] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Achieving high electron mobility in SrTiO3 films is of significant interest, particularly in relation to technological applications such as oxide semiconductors, field-induced superconductors, and thermoelectric generators. One route to achieving high electron mobility is growth of high quality SrTiO3 films with low defect concentrations. Another approach for mobility enhancement is applying a strain to the crystal. However, the maximum mobilities obtainable by these approaches are limited both by external and internal factors (currently available fabrication techniques, and maximum crystal strain, for example). In this paper, we demonstrate a unique crystal engineering approach to alter the strain in Nb-doped SrTiO3 films based on the deliberate introduction of Sr vacancy clusters. Nb-doped SrTiO3 films produced in this manner are found to exhibit remarkably enhanced electron mobilities (exceeding 53,000 cm(2) V(-1) s(-1)). This method of defect engineering is expected to enable tuning and enhancement of electron mobilities not only in SrTiO3 films, but also in thin films and bulk crystals of other perovskite-type materials.
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Affiliation(s)
- Shunsuke Kobayashi
- Nanostructures Research Laboratory, Japan Fine Ceramics Center , Atsuta, Nagoya 456-8587, Japan
| | - Yuki Mizumukai
- Department of Advanced Materials Science, The University of Tokyo , Kashiwa, Chiba 277-8561, Japan
| | - Tsuyoshi Ohnishi
- National Institute for Materials Science , Tsukuba, Ibaraki 305-0044, Japan
| | - Naoya Shibata
- Institute of Engineering Innovation, The University of Tokyo , Bunkyo, Tokyo 113-8656, Japan
- PRESTO, Japan Science and Technology Agency , Saitama 332-0012, Japan
| | - Yuichi Ikuhara
- Nanostructures Research Laboratory, Japan Fine Ceramics Center , Atsuta, Nagoya 456-8587, Japan
- Institute of Engineering Innovation, The University of Tokyo , Bunkyo, Tokyo 113-8656, Japan
| | - Takahisa Yamamoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center , Atsuta, Nagoya 456-8587, Japan
- Department of Advanced Materials Science, The University of Tokyo , Kashiwa, Chiba 277-8561, Japan
- Department of Quantum Engineering, Nagoya University , Chikusa, Nagoya 464-8603, Japan
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20
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Zhou Y, Rabe KM. Coupled Nonpolar-Polar Metal-Insulator Transition in 1∶1 SrCrO(3)/SrTiO(3) Superlattices: A First-Principles Study. PHYSICAL REVIEW LETTERS 2015; 115:106401. [PMID: 26382686 DOI: 10.1103/physrevlett.115.106401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Indexed: 06/05/2023]
Abstract
Using first-principles calculations, we determined the epitaxial-strain dependence of the ground state of the 1∶1 SrCrO(3)/SrTiO(3) superlattice. The superlattice layering leads to significant changes in the electronic states near the Fermi level, derived from Cr t(2g) orbitals. An insulating phase is found when the tensile strain is greater than 2.2% relative to unstrained cubic SrTiO(3). The insulating character is shown to arise from Cr t(2g) orbital ordering, which is produced by an in-plane polar distortion that couples to the superlattice d bands and is stabilized by epitaxial strain. This effect can be used to engineer the band structure near the Fermi level in transition metal oxide superlattices.
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Affiliation(s)
- Yuanjun Zhou
- Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Karin M Rabe
- Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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21
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Choi SY, Kim SD, Choi M, Lee HS, Ryu J, Shibata N, Mizoguchi T, Tochigi E, Yamamoto T, Kang SJL, Ikuhara Y. Assessment of Strain-Generated Oxygen Vacancies Using SrTiO₃ Bicrystals. NANO LETTERS 2015; 15:4129-4134. [PMID: 26000901 DOI: 10.1021/acs.nanolett.5b01245] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Atomic-scale defects strongly influence the electrical and optical properties of materials, and their impact can be more pronounced in localized dimensions. Here, we directly demonstrate that strain triggers the formation of oxygen vacancies in complex oxides by examining the tilt boundary of SrTiO3 bicrystals. Through transmission electron microscopy and electron energy loss spectroscopy, we identify strains along the tilt boundary and oxygen vacancies in the strain-imposed regions between dislocation cores. First-principles calculations support that strains, irrespective of their type or sign, lower the formation energy of oxygen vacancies, thereby enhancing vacancy formation. Finally, current-voltage measurements confirm that such oxygen vacancies at the strained boundary result in a decrease of the nonlinearity of the I-V curve as well as the resistivity. Our results strongly indicate that oxygen vacancies are preferentially formed and are segregated at the regions where strains accumulate, such as heterogeneous interfaces and grain boundaries.
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Affiliation(s)
| | | | | | | | | | - Naoya Shibata
- §Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Teruyasu Mizoguchi
- ∥Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan
| | - Eita Tochigi
- §Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Takahisa Yamamoto
- ⊥Department of Quantum Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Suk-Joong L Kang
- #Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
| | - Yuichi Ikuhara
- §Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
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22
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Tyunina M, Yao L, Chvostova D, Dejneka A, Kocourek T, Jelinek M, Trepakov V, van Dijken S. Concurrent bandgap narrowing and polarization enhancement in epitaxial ferroelectric nanofilms. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2015; 16:026002. [PMID: 27877779 PMCID: PMC5036465 DOI: 10.1088/1468-6996/16/2/026002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/04/2015] [Indexed: 05/28/2023]
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 KTaO3, KNbO3 (KNO), and NaNbO3 (NNO) with a thickness of 10-30 unit cells. Control of the bandgap is achieved using heteroepitaxial growth of new structural phases on SrTiO3 (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.
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Affiliation(s)
| | - Lide Yao
- NanoSpin, Department of Applied Physics, Aalto University School of Science, PO Box 15100, FI-00076 Aalto, Finland
| | - Dagmar Chvostova
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - Alexandr Dejneka
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - Tomas Kocourek
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - Miroslav Jelinek
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - Vladimir Trepakov
- Ioffe Physical-Technical Institute RAS, 194021 St. Petersburg, Russia
| | - Sebastiaan van Dijken
- NanoSpin, Department of Applied Physics, Aalto University School of Science, PO Box 15100, FI-00076 Aalto, Finland
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23
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Yu J, Yan Q, Chen W, Jain A, Neaton JB, Persson KA. First-principles study of electronic structure and photocatalytic properties of MnNiO3 as an alkaline oxygen-evolution photocatalyst. Chem Commun (Camb) 2015; 51:2867-70. [DOI: 10.1039/c4cc08111k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present a first-principles study of MnNiO3, a promising oxygen-evolution photocatalyst.
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Affiliation(s)
- Jie Yu
- Joint Center for Artificial Photosynthesis
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
- Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory
| | - Qimin Yan
- Molecular Foundry
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
- Department of Physics
| | - Wei Chen
- Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Anubhav Jain
- Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Jeffrey B. Neaton
- Molecular Foundry
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
- Department of Physics
| | - Kristin A. Persson
- Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory
- Berkeley
- USA
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24
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Wang F, Sun YY, Hatch JB, Xing H, Zhu X, Zhang H, Xu X, Luo H, Perera S, Zhang S, Zeng H. Realizing chemical codoping in TiO2. Phys Chem Chem Phys 2015; 17:17989-94. [DOI: 10.1039/c5cp02020d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
N and P chemical codoping of TiO2 has been experimentally demonstrated. The band gap of TiO2 can be reduced from 3.2 eV to 1.8 eV, without affecting the CBM position.
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25
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Nazir S, Yang K. First-principles characterization of the critical thickness for forming metallic states in strained LaAlO₃/SrTiO₃(001) heterostructure. ACS APPLIED MATERIALS & INTERFACES 2014; 6:22351-22358. [PMID: 25486683 DOI: 10.1021/am506336w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The emerging two-dimensional electron gas (2DEG) at the interface between polar LaAlO3 (LAO) and nonpolar SrTiO3 (STO) provides potential applications in low-dimensional nanoelectronic devices because of its exceptional electron transport property. To form 2DEG in the LAO/STO heterostructure (HS), a minimum thickness of approximately 4 unit cells of LAO is necessary. Herein, we modeled the n-type (TiO2)(0)/(LaO)(+1) HS by depositing (LAO)n (n = 4, 5, and 6) thin films on the STO substrate and explored strain effects on the critical thickness for forming 2DEG in the LAO/STO HS-based slab systems using first-principles electronic structure calculations. A vacuum layer was added along the [001] direction on the LAO film to resemble the actual epitaxial growth process of the materials. An insulator-to-metal transition is predicted in unstrained (LAO)n/STO systems when n ≥ 5. Our calculations indicate that O 2px/py states give rise to the surface conductivity, while Ti 3dxy states are responsible for the interfacial conductivity. For the tensilely strained HS system, an increased film thickness of LAO (n ≥ 6) is required to form the 2DEG, and a remarkable shift of O 2p orbitals toward higher energy in LAO layers is found, which is caused by the strain-induced change of the electrostatic potential. For the compressively strained HS system, the critical thickness of LAO film for forming 2DEG is between 5 and 6 unit cells of LAO. In addition, our calculations suggest that the interfacial charge carrier density and magnetic moment can be optimized when a moderate tensile strain is applied on the STO substrate in the ab-plane.
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Affiliation(s)
- Safdar Nazir
- Department of NanoEngineering, University of California, San Diego , 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448, United States
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26
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Sando D, Barthélémy A, Bibes M. BiFeO3 epitaxial thin films and devices: past, present and future. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:473201. [PMID: 25352066 DOI: 10.1088/0953-8984/26/47/473201] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The celebrated renaissance of the multiferroics family over the past ten years has also been that of its most paradigmatic member, bismuth ferrite (BiFeO3). Known since the 1960s to be a high temperature antiferromagnet and since the 1970s to be ferroelectric, BiFeO3 only had its bulk ferroic properties clarified in the mid-2000s. It is however the fabrication of BiFeO3 thin films and their integration into epitaxial oxide heterostructures that have fully revealed its extraordinarily broad palette of functionalities. Here we review the first decade of research on BiFeO3 films, restricting ourselves to epitaxial structures. We discuss how thickness and epitaxial strain influence not only the unit cell parameters, but also the crystal structure, illustrated for instance by the discovery of the so-called T-like phase of BiFeO3. We then present its ferroelectric and piezoelectric properties and their evolution near morphotropic phase boundaries. Magnetic properties and their modification by thickness and strain effects, as well as optical parameters, are covered. Finally, we highlight various types of devices based on BiFeO3 in electronics, spintronics, and optics, and provide perspectives for the development of further multifunctional devices for information technology and energy harvesting.
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Affiliation(s)
- D Sando
- Unité Mixte de Physique CNRS/Thales, 1 Avenue Fresnel, Campus de l'Ecole Polytechnique, 91767 Palaiseau, France, and Université Paris Sud, 91405 Orsay, France. Center for Correlated Electron Systems, Institute for Basic Science (IBS), and Department of Physics and Astronomy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-747, Republic of Korea
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27
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Sanchez-Santolino G, Cabero M, Varela M, Garcia-Barriocanal J, Leon C, Pennycook SJ, Santamaria J. Oxygen octahedral distortions in LaMO3/SrTiO3 superlattices. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2014; 20:825-831. [PMID: 24758834 DOI: 10.1017/s1431927614000750] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this work we study the interfaces between the Mott insulator LaMnO3 (LMO) and the band insulator SrTiO3 (STO) in epitaxially grown superlattices with different thickness ratios and different transport and magnetic behaviors. Using atomic resolution electron energy-loss spectral imaging, we analyze simultaneously the structural and chemical properties of these interfaces. We find changes in the oxygen octahedral tilts within the LaMnO3 layers when the thickness ratio between the manganite and the titanate layers is varied. Superlattices with thick LMO and ultrathin STO layers present unexpected octahedral tilts in the STO, along with a small amount of oxygen vacancies. On the other hand, thick STO layers exhibit undistorted octahedra while the LMO layers present reduced O octahedral distortions near the interfaces. These findings are discussed in view of the transport and magnetic differences found in previous studies.
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Affiliation(s)
| | - Mariona Cabero
- 1GFMC,Departamento de Fisica Aplicada III,Universidad Complutense de Madrid,28040 Madrid,Spain
| | - Maria Varela
- 1GFMC,Departamento de Fisica Aplicada III,Universidad Complutense de Madrid,28040 Madrid,Spain
| | | | - Carlos Leon
- 1GFMC,Departamento de Fisica Aplicada III,Universidad Complutense de Madrid,28040 Madrid,Spain
| | - Stephen J Pennycook
- 4Department of Materials Science and Engineering,The University of Tennessee,Knoxville,TN 37996,USA
| | - Jacobo Santamaria
- 1GFMC,Departamento de Fisica Aplicada III,Universidad Complutense de Madrid,28040 Madrid,Spain
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28
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Aschauer U, Spaldin NA. Competition and cooperation between antiferrodistortive and ferroelectric instabilities in the model perovskite SrTiO3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:122203. [PMID: 24594645 DOI: 10.1088/0953-8984/26/12/122203] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We use density functional theory to explore the interplay between octahedral rotations and ferroelectricity in the model compound SrTiO3. We find that over the experimentally relevant range octahedral rotations suppress ferroelectricity as is generally assumed in the literature. Somewhat surprisingly, we observe that at larger angles the previously weakened ferroelectric instability strengthens significantly. By analyzing geometry changes, energetics, force constants and charges, we explain the mechanisms behind this transition from competition to cooperation with increasing octahedral rotation angle.
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Affiliation(s)
- Ulrich Aschauer
- Materials Theory, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zürich, Switzerland
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29
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Kim YM, Kumar A, Hatt A, Morozovska AN, Tselev A, Biegalski MD, Ivanov I, Eliseev EA, Pennycook SJ, Rondinelli JM, Kalinin SV, Borisevich AY. Interplay of octahedral tilts and polar order in BiFeO3 films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:2497-2504. [PMID: 23505214 DOI: 10.1002/adma.201204584] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 01/04/2013] [Indexed: 06/01/2023]
Abstract
Heterointerface stabilization of a distinct nonpolar BiFeO3 phase occurs simultaneously with changes in octahedral tilts. The resulting phase arises via suppression of polarization by a structural order parameter and can thus be identified as anti-ferroelectric (Fe displacements - bottom panel). The phase is metastable and can be switched into a polar ferroelectric state (top panel) under an applied electric bias.
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Affiliation(s)
- Young-Min Kim
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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30
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Kim JW, Thompson P, Brown S, Normile PS, Schlueter JA, Shkabko A, Weidenkaff A, Ryan PJ. Emergent superstructural dynamic order due to competing antiferroelectric and antiferrodistortive instabilities in bulk EuTiO3. PHYSICAL REVIEW LETTERS 2013; 110:027201. [PMID: 23383935 DOI: 10.1103/physrevlett.110.027201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Indexed: 06/01/2023]
Abstract
Microscopic structural instabilities of EuTiO3 single crystals were investigated by synchrotron x-ray diffraction. Antiferrodistortive (AFD) oxygen octahedron rotational order was observed alongside Ti derived antiferroelectric distortions. The competition between the two instabilities is reconciled through a cooperatively modulated structure allowing both to coexist. The combination of electric and magnetic fields increases the population of the modulated AFD order, illustrating how the origin of the large magnetoelectric coupling derives from the dynamic equilibrium between AFD and polar instabilities.
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Affiliation(s)
- Jong-Woo Kim
- X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
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31
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Bennett JW, Rabe KM. Integration of first-principles methods and crystallographic database searches for new ferroelectrics: Strategies and explorations. J SOLID STATE CHEM 2012. [DOI: 10.1016/j.jssc.2012.05.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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32
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Bennett JW. Discovery and Design of Functional Materials: Integration of Database Searching and First Principles Calculations. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.phpro.2012.05.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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