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Seo J, Lee H, Eom K, Byun J, Min T, Lee J, Lee K, Eom CB, Oh SH. Feld-induced modulation of two-dimensional electron gas at LaAlO 3/SrTiO 3 interface by polar distortion of LaAlO 3. Nat Commun 2024; 15:5268. [PMID: 38902225 PMCID: PMC11189907 DOI: 10.1038/s41467-024-48946-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/19/2024] [Indexed: 06/22/2024] Open
Abstract
Since the discovery of two-dimensional electron gas at the LaAlO3/SrTiO3 interface, its intriguing physical properties have garnered significant interests for device applications. Yet, understanding its response to electrical stimuli remains incomplete. Our in-situ transmission electron microscopy analysis of a LaAlO3/SrTiO3 two-dimensional electron gas device under electrical bias reveals key insights. Inline electron holography visualized the field-induced modulation of two-dimensional electron gas at the interface, while electron energy loss spectroscopy showed negligible electromigration of oxygen vacancies. Instead, atom-resolved imaging indicated that electric fields trigger polar distortion in the LaAlO3 layer, affecting two-dimensional electron gas modulation. This study refutes the previously hypothesized role of oxygen vacancies, underscoring the lattice flexibility of LaAlO3 and its varied polar distortions under electric fields as central to two-dimensional electron gas dynamics. These findings open pathways for advanced oxide nanoelectronics, exploiting the interplay of polar and nonpolar distortions in LaAlO3.
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Affiliation(s)
- Jinsol Seo
- Department of Energy Engineering, KENTECH Institute for Energy Materials and Devices, Korea Institute of Energy Technology (KENTECH), Naju, Republic of Korea
| | - Hyungwoo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Energy Systems Research and Department of Physics, Ajou University, Suwon, Republic of Korea
| | - Kitae Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jinho Byun
- Department of Energy Engineering, KENTECH Institute for Energy Materials and Devices, Korea Institute of Energy Technology (KENTECH), Naju, Republic of Korea
| | - Taewon Min
- Department of Physics, Pusan National University, Busan, Republic of Korea
| | - Jaekwang Lee
- Department of Physics, Pusan National University, Busan, Republic of Korea
| | - Kyoungjun Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Chang-Beom Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sang Ho Oh
- Department of Energy Engineering, KENTECH Institute for Energy Materials and Devices, Korea Institute of Energy Technology (KENTECH), Naju, Republic of Korea.
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2
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Li Y, Huang Y, Liu X, Wang Y, Yuan L. Density functional theory study on the formation mechanism and electrical properties of two-dimensional electron gas in biaxial-strained LaGaO 3 /BaSnO 3 heterostructure. Sci Rep 2024; 14:10259. [PMID: 38704471 DOI: 10.1038/s41598-024-60893-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Accepted: 04/29/2024] [Indexed: 05/06/2024] Open
Abstract
The two-dimensional electron gas (2DEG) in BaSnO3 -based heterostructure (HS) has received tremendous attention in the electronic applications because of its excellent electron migration characteristic. We modeled the n-type (LaO)+ /(SnO2 )0 interface by depositing LaGaO3 film on the BaSnO3 substrate and explored strain effects on the critical thickness for forming 2DEG and electrical properties of LaGaO3 /BaSnO3 HS system using first-principles electronic structure calculations. The results indicate that to form 2DEG in the unstrained LaGaO3 /BaSnO3 HS system, a minimum thickness of approximately 4 unit cells of LaGaO3 film is necessary. An increased film thickness of LaGaO3 is required to form the 2DEG for -3%-biaxially-strained HS system and the critical thickness is 3 unit cells for 3%-baxially-strained HS system, which is caused by the strain-induced change of the electrostatic potential in LaGaO3 film. In addition, the biaxial strain plays an important role in tailoring the electrical properties of 2DEG in LaGaO3 /BaSnO3 HS syestem. The interfacial charge carrier density, electron mobility and electrical conductivity can be optimized when a moderate tensile strain is applied on the BaSnO3 substrate in the ab-plane.
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Affiliation(s)
- Yuling Li
- Key Laboratory of Fluid and Power Machinery, School of Material Science and Engineering, Xihua University, Chengdu, 610039, People's Republic of China
| | - Yuxi Huang
- Key Laboratory of Fluid and Power Machinery, School of Material Science and Engineering, Xihua University, Chengdu, 610039, People's Republic of China
| | - Xiaohua Liu
- Key Laboratory of Fluid and Power Machinery, School of Material Science and Engineering, Xihua University, Chengdu, 610039, People's Republic of China
| | - Yaqin Wang
- Key Laboratory of Fluid and Power Machinery, School of Material Science and Engineering, Xihua University, Chengdu, 610039, People's Republic of China.
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, People's Republic of China.
| | - Le Yuan
- Key Laboratory of Fluid and Power Machinery, School of Material Science and Engineering, Xihua University, Chengdu, 610039, People's Republic of China
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3
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Fang L, Chen C, Sundaresan A, Narayana C, Ter-Oganessian N, Pyatakov AP, Cao S, Zhang J, Ren W. The CdTiO 3/BaTiO 3 superlattice interface from first principles. NANOSCALE 2021; 13:8506-8513. [PMID: 33904555 DOI: 10.1039/d1nr00374g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The oxide interface has been studied extensively in the past decades and exhibits different physical properties from the constituent bulks. Using first-principles electronic structure calculations, we investigated the interface of CdTiO3/BaTiO3 (CTO/BTO) superlattice with ferroelectric BaTiO3. In this case, the conduction bands of CdTiO3 are composed of Cd-5s orbitals with low electron effective mass and nondegenerate dispersion, and thus expected to have high mobility. We predicted a controllable conductivity at the interface, and further analyzed how the polarization direction and strength affect the conductivity. We also explored the relationship between two components: thickness and polarization. Intriguingly, the total polarization in CTO/BTO might be even larger than that of ferroelectric bulk BaTiO3. Therefore, we found a way to maximize the superlattice polarization by increasing the fraction of the CdTiO3 layers, based on the interesting dependence of the total polarization and CTO/BTO ratio.
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Affiliation(s)
- Le Fang
- Materials Genome Institute, International Center for Quantum and Molecular Structures, Shanghai University, Shanghai 200444, China.
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4
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Kim JR, Jang J, Go KJ, Park SY, Roh CJ, Bonini J, Kim J, Lee HG, Rabe KM, Lee JS, Choi SY, Noh TW, Lee D. Stabilizing hidden room-temperature ferroelectricity via a metastable atomic distortion pattern. Nat Commun 2020; 11:4944. [PMID: 33009380 PMCID: PMC7532175 DOI: 10.1038/s41467-020-18741-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 09/10/2020] [Indexed: 11/09/2022] Open
Abstract
Nonequilibrium atomic structures can host exotic and technologically relevant properties in otherwise conventional materials. Oxygen octahedral rotation forms a fundamental atomic distortion in perovskite oxides, but only a few patterns are predominantly present at equilibrium. This has restricted the range of possible properties and functions of perovskite oxides, necessitating the utilization of nonequilibrium patterns of octahedral rotation. Here, we report that a designed metastable pattern of octahedral rotation leads to robust room-temperature ferroelectricity in CaTiO3, which is otherwise nonpolar down to 0 K. Guided by density-functional theory, we selectively stabilize the metastable pattern, distinct from the equilibrium pattern and cooperative with ferroelectricity, in heteroepitaxial films of CaTiO3. Atomic-scale imaging combined with deep neural network analysis confirms a close correlation between the metastable pattern and ferroelectricity. This work reveals a hidden but functional pattern of oxygen octahedral rotation and opens avenues for designing multifunctional materials.
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Affiliation(s)
- Jeong Rae Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea
| | - Jinhyuk Jang
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea
| | - Kyoung-June Go
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea
| | - Se Young Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Korea.
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea.
- Department of Physics, Soongsil University, Seoul, 07027, Korea.
| | - Chang Jae Roh
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Korea
| | - John Bonini
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854-8019, USA
| | - Jinkwon Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea
| | - Han Gyeol Lee
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea
| | - Karin M Rabe
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, 08854-8019, USA
| | - Jong Seok Lee
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Korea
| | - Si-Young Choi
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea.
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Korea.
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea.
| | - Daesu Lee
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Korea.
- Asia Pacific Center for Theoretical Physics, Pohang, 37673, Korea.
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5
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Ding J, Cheng J, Dogan F, Li Y, Lin W, Yao Y, Manchon A, Yang K, Wu T. Two-Dimensional Electron Gas at the Spinel/Perovskite Interface: Suppression of Polar Catastrophe by an Ultrathin Layer of Interfacial Defects. ACS APPLIED MATERIALS & INTERFACES 2020; 12:42982-42991. [PMID: 32829635 DOI: 10.1021/acsami.0c13337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Two-dimensional electron gas (2DEG) at the interface between two insulating perovskite oxides has attracted much interest for both fundamental physics and potential applications. Here, we report the discovery of a new 2DEG formed at the interface between spinel MgAl2O4 and perovskite SrTiO3. Transport measurements, electron microscopy imaging, and first-principles calculations reveal that the interfacial 2DEG is closely related to the symmetry breaking at the MgAl2O4/SrTiO3 interface. The critical film thickness for the insulator-to-metal transition is approximately 32 Å, which is twice as thick as that reported on the widely studied LaAlO3/SrTiO3 system. Scanning transmission electron microscopy imaging indicates the formation of interfacial Ti-Al antisite defects with a thickness of ∼4 Å. First-principles density functional theory calculations indicate that the coexistence of the antisite defects and surface oxygen vacancies may explain the formation of interfacial 2DEG as well as the observed critical film thickness. The discovery of 2DEG at the spinel/perovskite interface introduces a new material platform for designing oxide interfaces with desired characteristics.
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Affiliation(s)
- Junfeng Ding
- Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
| | - Jianli Cheng
- Department of NanoEngineering, University of California, San Diego, La Jolla, California 92093-0448, United States
| | - Fatih Dogan
- College of Engineering and Technology, American University of the Middle East, Kuwait
| | - Yangyang Li
- Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore
| | - Weinan Lin
- Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore
| | - Yingbang Yao
- School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, People's Republic of China
| | - Aurelien Manchon
- Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
- Aix-Marseille Univ, CNRS, CINaM, Marseille 13288, France
| | - Kesong Yang
- Department of NanoEngineering, University of California, San Diego, La Jolla, California 92093-0448, United States
| | - Tom Wu
- School of Materials Science and Engineering, University of New South Wales (UNSW), Sydney, NSW 2052, Australia
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6
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Abstract
Dielectrics have long been considered as unsuitable for pure electrical switches; under weak electric fields, they show extremely low conductivity, whereas under strong fields, they suffer from irreversible damage. Here, we show that flexoelectricity enables damage-free exposure of dielectrics to strong electric fields, leading to reversible switching between electrical states—insulating and conducting. Applying strain gradients with an atomic force microscope tip polarizes an ultrathin film of an archetypal dielectric SrTiO3 via flexoelectricity, which in turn generates non-destructive, strong electrostatic fields. When the applied strain gradient exceeds a certain value, SrTiO3 suddenly becomes highly conductive, yielding at least around a 108-fold decrease in room-temperature resistivity. We explain this phenomenon, which we call the colossal flexoresistance, based on the abrupt increase in the tunneling conductance of ultrathin SrTiO3 under strain gradients. Our work extends the scope of electrical control in solids, and inspires further exploration of dielectric responses to strong electromechanical fields. Manipulating the electric state of large band gap dielectrics without any damage is quite challenging. Here, the authors demonstrate by mechanically introducing strain gradients that large electric fields are generated via flexoelectric interactions, resulting in a reversible Zener breakdown in SrTiO3, changing the resistivity by 108.
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7
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Chapman KS, Atkinson WA. Modified transverse Ising model for the dielectric properties of SrTiO 3 films and interfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:065303. [PMID: 31634883 DOI: 10.1088/1361-648x/ab4fa7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The transverse Ising model (TIM), with pseudospins representing the lattice polarization, is often used as a simple description of ferroelectric materials. However, we demonstrate that the TIM, as it is usually formulated, provides an incorrect description of SrTiO3 films and interfaces because of its inadequate treatment of spatial inhomogeneity. We correct this deficiency by adding a pseudospin anisotropy to the model. We demonstrate the physical need for this term by comparison of the TIM to a typical Landau-Ginzburg-Devonshire model. We then demonstrate the physical consequences of the modification for two model systems: a ferroelectric thin film, and a metallic LaAlO3/SrTiO3 interface. We show that, in both cases, the modified TIM has a substantially different polarization profile than the conventional TIM. In particular, at low temperatures the formation of quantized states at LaAlO3/SrTiO3 interfaces only occurs in the modified TIM.
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Affiliation(s)
- Kelsey S Chapman
- Department of Physics and Astronomy, Trent University, Peterborough, Ontario, K9L 0G2, Canada
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8
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Fang L, Chen C, Yang Y, Wu Y, Hu T, Zhao G, Zhu Q, Ren W. First-principles studies of a two-dimensional electron gas at the interface of polar/polar LaAlO3/KNbO3 superlattices. Phys Chem Chem Phys 2019; 21:8046-8053. [DOI: 10.1039/c8cp07202g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We explored the possibility of producing a two-dimensional electron gas (2DEG) in polar/polar (LaAlO3)m/(KNbO3)n perovskite superlattices that have N type and P type interfaces using the first-principles electronic structure calculations.
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Affiliation(s)
- Le Fang
- Materials Genome Institute
- International Center for Quantum and Molecular Structures
- Shanghai University
- Shanghai 200444
- China
| | - Chen Chen
- Materials Genome Institute
- International Center for Quantum and Molecular Structures
- Shanghai University
- Shanghai 200444
- China
| | - Yali Yang
- Materials Genome Institute
- International Center for Quantum and Molecular Structures
- Shanghai University
- Shanghai 200444
- China
| | - Yabei Wu
- Materials Genome Institute
- International Center for Quantum and Molecular Structures
- Shanghai University
- Shanghai 200444
- China
| | - Tao Hu
- Materials Genome Institute
- International Center for Quantum and Molecular Structures
- Shanghai University
- Shanghai 200444
- China
| | - Guodong Zhao
- Materials Genome Institute
- International Center for Quantum and Molecular Structures
- Shanghai University
- Shanghai 200444
- China
| | - Qiang Zhu
- Department of Physics and Astronomy
- High Pressure Science and Engineering Center
- University of Nevada
- Las Vegas
- USA
| | - Wei Ren
- Materials Genome Institute
- International Center for Quantum and Molecular Structures
- Shanghai University
- Shanghai 200444
- China
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9
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Wang L, Pan W, Hu WX, Sun DY. Strain-induced indirect-to-direct bandgap transition in an np-type LaAlO 3/SrTiO 3(110) superlattice. Phys Chem Chem Phys 2019; 21:7075-7082. [DOI: 10.1039/c8cp07761d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
By applying uniaxial in-plane strains, an indirect-to-direct bandgap transition occurs in the polar LaAlO3/SrTiO3 (110) superlattices.
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Affiliation(s)
- L. Wang
- Department of Physics
- East China Normal University
- Shanghai 200241
- People's Republic of China
| | - W. Pan
- Department of Physics
- East China Normal University
- Shanghai 200241
- People's Republic of China
| | - W. X. Hu
- The computer Center
- East China Normal University
- Shanghai 200241
- People's Republic of China
| | - D. Y. Sun
- Department of Physics
- East China Normal University
- Shanghai 200241
- People's Republic of China
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10
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Cheng J, Luo J, Yang K. Comparison Studies of Interfacial Electronic and Energetic Properties of LaAlO 3/TiO 2 and TiO 2/LaAlO 3 Heterostructures from First-Principles Calculations. ACS APPLIED MATERIALS & INTERFACES 2017; 9:7682-7690. [PMID: 28139115 DOI: 10.1021/acsami.6b12254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
By using first-principles electronic structure calculations, we studied electronic and energetic properties of perovskite oxide heterostructures with different epitaxial growth order between anatase TiO2 and LaAlO3. Two types of heterostructures, i.e., TiO2 film grown on LaAlO3 substrate (TiO2/LaAlO3) and LaAlO3 film grown on TiO2 substrate (LaAlO3/TiO2), were modeled. The TiO2/LaAlO3 model is intrinsically metallic and thus does not exhibit an insulator-to-metal transition as TiO2 film thickness increases; in contrast, the LaAlO3/TiO2 model shows an insulator-to-metal transition as the LaAlO3 film thickness increases up to 4 unit cells. The former model has a larger interfacial charge carrier density (n ∼ 1014 cm-2) and smaller electron effective mass (0.47me) than the later one (n ∼ 1013 cm-2, and 0.70me). The interfacial energetics calculations indicate that the TiO2/LaAlO3 model is energetically more favorable than the LaAlO3/TiO2 model, and the former has a stronger interface cohesion than the later model. This research provides fundamental insights into the different interfacial electronic and energetic properties of TiO2/LaAlO3 and LaAlO3/TiO2 heterostructures.
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Affiliation(s)
- Jianli Cheng
- Department of NanoEngineering, University of California, San Diego , 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448, United States
| | - Jian Luo
- Department of NanoEngineering, University of California, San Diego , 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448, United States
| | - Kesong Yang
- 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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11
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Guo H, Saidi WA, Zhao J. Tunability of the two-dimensional electron gas at the LaAlO 3/SrTiO 3 interface by strain-induced ferroelectricity. Phys Chem Chem Phys 2016; 18:28474-28484. [PMID: 27711681 DOI: 10.1039/c6cp04769f] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The two-dimensional electron gas (2DEG) formed at the interface between two insulating materials LaAlO3 (LAO) and SrTiO3 (STO) has recently generated a lot of interest. Here, based on first-principles density functional theory calculations, we investigate the existence and stability of the 2DEG under the application of a biaxial strain on the LAO/STO(001) heterostructure. The compressive strain induces ferroelectric (FE) polarization in STO, which allows for the tunability of the 2DEG by reversing the STO polarization orientation. We show that the formation of the 2DEG is unstable when LAO and STO have the same polarization direction. On the other hand, the 2DEG will always form if the two polarizations are in the opposite directions regardless of the LAO thickness, which is in contrast to the unstrained interface that has a critical thickness for stabilizing the 2DEG. We show that the underpinnings of this behavior are due to charge passivation and band gap alignment.
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Affiliation(s)
- Hongli Guo
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China. and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wissam A Saidi
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
| | - Jin Zhao
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China. and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and Department of Physics, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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12
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Wang Y, Tang W, Cheng J, Behtash M, Yang K. Creating Two-Dimensional Electron Gas in Polar/Polar Perovskite Oxide Heterostructures: First-Principles Characterization of LaAlO3/A(+)B(5+)O3. ACS APPLIED MATERIALS & INTERFACES 2016; 8:13659-13668. [PMID: 27160513 DOI: 10.1021/acsami.6b02399] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
By using first-principles electronic structure calculations, we explored the possibility of producing two-dimensional electron gas (2DEG) at the polar/polar (LaO)(+)/(BO2)(+) interface in the LaAlO3/A(+)B(5+)O3 (A = Na and K, B = Nb and Ta) heterostructures (HS). Unlike the prototype polar/nonpolar LaAlO3/SrTiO3 HS system where there exists a least film thickness of four LaAlO3 unit cells to have an insulator-to-metal transition, we found that the polar/polar LaAlO3/A(+)B(5+)O3 HS systems are intrinsically conducting at their interfaces without an insulator-to-metal transition. The interfacial charge carrier densities of these polar/polar HS systems are on the order of 10(14) cm(-2), much larger than that of the LaAlO3/SrTiO3 system. This is mainly attributed to two donor layers, i.e., (LaO)(+) and (BO2)(+) (B = Nb and Ta), in the polar/polar LaAlO3/A(+)B(5+)O3 systems, while only one (LaO)(+) donor layer in the polar/nonpolar LaAlO3/SrTiO3 system. In addition, it is expected that, due to less localized Nb 4d and Ta 5d orbitals with respect to Ti 3d orbitals, these LaAlO3/A(+)B(5+)O3 HS systems can exhibit potentially higher electron mobility because of their smaller electron effective mass than that in the LaAlO3/SrTiO3 system. Our results demonstrate that the electronic reconstruction at the polar/polar interface could be an alternative way to produce superior 2DEG in the perovskite-oxide-based HS systems.
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Affiliation(s)
- Yaqin Wang
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China , Chengdu, Sichuan 610054, P. R. China
- Department of NanoEngineering, University of California, San Diego , 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448, United States
| | - Wu Tang
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China , Chengdu, Sichuan 610054, P. R. China
| | - Jianli Cheng
- Department of NanoEngineering, University of California, San Diego , 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448, United States
| | - Maziar Behtash
- Department of NanoEngineering, University of California, San Diego , 9500 Gilman Drive, Mail Code 0448, La Jolla, California 92093-0448, United States
| | - Kesong Yang
- 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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13
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Wang Y, Tang W, Cheng J, Nazir S, Yang K. High-mobility two-dimensional electron gas in SrGeO3- and BaSnO3-based perovskite oxide heterostructures: an ab initio study. Phys Chem Chem Phys 2016; 18:31924-31929. [DOI: 10.1039/c6cp05572a] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
First-principles electronic structure calculations predict that SrGeO3 and BaSnO3 can be substrate materials for achieving a high-mobility two-dimensional electron gas in perovskite oxide heterostructures.
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Affiliation(s)
- Yaqin Wang
- State Key Laboratory of Electronic Thin Films and Integrated Devices
- University of Electronic Science and Technology of China
- Chengdu 610054
- P. R. China
- Department of NanoEngineering
| | - Wu Tang
- State Key Laboratory of Electronic Thin Films and Integrated Devices
- University of Electronic Science and Technology of China
- Chengdu 610054
- P. R. China
| | - Jianli Cheng
- Department of NanoEngineering
- University of California
- La Jolla
- USA
| | - Safdar Nazir
- Department of NanoEngineering
- University of California
- La Jolla
- USA
| | - Kesong Yang
- Department of NanoEngineering
- University of California
- La Jolla
- USA
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