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Rose MA, Šmíd B, Vorokhta M, Slipukhina I, Andrä M, Bluhm H, Duchoň T, Ležaić M, Chambers SA, Dittmann R, Mueller DN, Gunkel F. Identifying Ionic and Electronic Charge Transfer at Oxide Heterointerfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2004132. [PMID: 33263190 DOI: 10.1002/adma.202004132] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/31/2020] [Indexed: 06/12/2023]
Abstract
The ability to tailor oxide heterointerfaces has led to novel properties in low-dimensional oxide systems. A fundamental understanding of these properties is based on the concept of electronic charge transfer. However, the electronic properties of oxide heterointerfaces crucially depend on their ionic constitution and defect structure: ionic charges contribute to charge transfer and screening at oxide interfaces, triggering a thermodynamic balance of ionic and electronic structures. Quantitative understanding of the electronic and ionic roles regarding charge-transfer phenomena poses a central challenge. Here, the electronic and ionic structure is simultaneously investigated at the prototypical charge-transfer heterointerface, LaAlO3 /SrTiO3 . Applying in situ photoemission spectroscopy under oxygen ambient, ionic and electronic charge transfer is deconvoluted in response to the oxygen atmosphere at elevated temperatures. In this way, both the rich and variable chemistry of complex oxides and the associated electronic properties are equally embraced. The interfacial electron gas is depleted through an ionic rearrangement in the strontium cation sublattice when oxygen is applied, resulting in an inverse and reversible balance between cation vacancies and electrons, while the mobility of ionic species is found to be considerably enhanced as compared to the bulk. Triggered by these ionic phenomena, the electronic transport and magnetic signature of the heterointerface are significantly altered.
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Affiliation(s)
- Marc-André Rose
- Institute for Electronic Materials (IWE 2), and Juelich-Aachen Research Alliance for Fundamentals on Future Information Technology (JARA-FIT), RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, and JARA-FIT, 52425, Jülich, Germany
| | - Břetislav Šmíd
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, Prague, 180 00, Czech Republic
| | - Mykhailo Vorokhta
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, Prague, 180 00, Czech Republic
| | - Ivetta Slipukhina
- Peter Grünberg Institute 1 and Institute for Advanced Simulation, Forschungszentrum Jülich GmbH and JARA-FIT, 52425, Jülich, Germany
| | - Michael Andrä
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, and JARA-FIT, 52425, Jülich, Germany
| | - Hendrik Bluhm
- Chemical Sciences Division, Lawrence Berkeley National Lab., Berkeley, CA, 94720, USA
- Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany
| | - Tomáš Duchoň
- Peter Grünberg Institute 6, and JARA-FIT, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Marjana Ležaić
- Peter Grünberg Institute 1 and Institute for Advanced Simulation, Forschungszentrum Jülich GmbH and JARA-FIT, 52425, Jülich, Germany
| | - Scott A Chambers
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Regina Dittmann
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, and JARA-FIT, 52425, Jülich, Germany
| | - David N Mueller
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, and JARA-FIT, 52425, Jülich, Germany
- Peter Grünberg Institute 6, and JARA-FIT, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Felix Gunkel
- Institute for Electronic Materials (IWE 2), and Juelich-Aachen Research Alliance for Fundamentals on Future Information Technology (JARA-FIT), RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, and JARA-FIT, 52425, Jülich, Germany
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Kim TL, Choi MJ, Lee TH, Sohn W, Jang HW. Tailoring of Interfacial Band Offsets by an Atomically Thin Polar Insulating Layer To Enhance the Water-Splitting Performance of Oxide Heterojunction Photoanodes. NANO LETTERS 2019; 19:5897-5903. [PMID: 31095915 DOI: 10.1021/acs.nanolett.9b01431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
An important factor in the performance of photoelectrochemical water splitting is the band edge alignment of the photoelectrodes for efficient transport and transfer of photogenerated carriers. Many studies for improving charge transfer ability between the electrode and the electrolyte have been reported, while research to improve charge transfer at the interface of the photoactive semiconductor and the conducting substrate is largely lacking. Here, we demonstrate that the water-splitting performance of an oxide heterostructured photoelectrode can be increased 6-fold by inserting an atomically thin polar LaAlO3 interlayer compared with that of an oxide heterostructure without an insertion to modify interfacial band offsets. The electrically lowered Schottky barrier is driven by the atomically thin layer, and the charge transfer resistance between the oxides is reduced by up to 2 orders of magnitude upon insertion of LaAlO3, a wide-gap (5.6 eV) insulator. We show that the critical thickness of the polar layer for enhancing the charge transfer is 3 unit cells. The dipole moment from the polar sheets of LaAlO3 introduces an internal electric field, which modifies the effective band offsets in the device. This work serves as a proof of concept that photoelectrochemical performance can be improved by manipulating the band offsets of the heterostructure interface, suggesting a new design strategy for heterostructured water-splitting photoelectrodes.
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Affiliation(s)
- Taemin Ludvic Kim
- Department of Materials Science and Engineering, Research Institute of Advanced Materials , Seoul National University , Seoul 08826 , Republic of Korea
| | - Min-Ju Choi
- Department of Materials Science and Engineering, Research Institute of Advanced Materials , Seoul National University , Seoul 08826 , Republic of Korea
| | - Tae Hyung Lee
- Department of Materials Science and Engineering, Research Institute of Advanced Materials , Seoul National University , Seoul 08826 , Republic of Korea
| | - Woonbae Sohn
- Department of Materials Science and Engineering, Research Institute of Advanced Materials , Seoul National University , Seoul 08826 , Republic of Korea
| | - Ho Won Jang
- Department of Materials Science and Engineering, Research Institute of Advanced Materials , Seoul National University , Seoul 08826 , Republic of Korea
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Yang H, Zhou G, Zhu Y, Gong GM, Zhang Q, Liao M, Li Z, Ding C, Meng F, Rafique M, Wang H, Gu L, Zhang D, Wang L, Xue QK. Superconductivity above 28 K in single unit cell FeSe films interfaced with GaO 2-δ layer on NdGaO 3(1 1 0). Sci Bull (Beijing) 2019; 64:490-494. [PMID: 36659735 DOI: 10.1016/j.scib.2019.03.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/12/2019] [Accepted: 03/13/2019] [Indexed: 01/21/2023]
Affiliation(s)
- Haohao Yang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Guanyu Zhou
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yuying Zhu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Guan-Ming Gong
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Qinghua Zhang
- Laboratory for Advanced Materials & Electron Microscopy, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Menghan Liao
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Zheng Li
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Cui Ding
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Fanqi Meng
- Laboratory for Advanced Materials & Electron Microscopy, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Mohsin Rafique
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Heng Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Lin Gu
- Laboratory for Advanced Materials & Electron Microscopy, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Ding Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; Collaborative Innovation Center of Quantum Matter, Beijing 100084, China.
| | - Lili Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; Collaborative Innovation Center of Quantum Matter, Beijing 100084, China.
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; Collaborative Innovation Center of Quantum Matter, Beijing 100084, China.
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Gobaut B, Orgiani P, Sambri A, di Gennaro E, Aruta C, Borgatti F, Lollobrigida V, Céolin D, Rueff JP, Ciancio R, Bigi C, Das PK, Fujii J, Krizmancic D, Torelli P, Vobornik I, Rossi G, Miletto Granozio F, Scotti di Uccio U, Panaccione G. Role of Oxygen Deposition Pressure in the Formation of Ti Defect States in TiO 2(001) Anatase Thin Films. ACS APPLIED MATERIALS & INTERFACES 2017; 9:23099-23106. [PMID: 28613812 DOI: 10.1021/acsami.7b03181] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We report the study of anatase TiO2(001)-oriented thin films grown by pulsed laser deposition on LaAlO3(001). A combination of in situ and ex situ methods has been used to address both the origin of the Ti3+-localized states and their relationship with the structural and electronic properties on the surface and the subsurface. Localized in-gap states are analyzed using resonant X-ray photoelectron spectroscopy and are related to the Ti3+ electronic configuration, homogeneously distributed over the entire film thickness. We find that an increase in the oxygen pressure corresponds to an increase in Ti3+ only in a well-defined range of deposition pressure; outside this range, Ti3+ and the strength of the in-gap states are reduced.
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Affiliation(s)
- Benoit Gobaut
- Elettra Sincrotrone Trieste S.c.p.A. , Basovizza, I-34012 Trieste, Italy
| | | | - Alessia Sambri
- CNR-SPIN, UOS Napoli , I-80126 Napoli, Italy
- Department of Physics, University of Napoli Federico II , I-80126 Napoli, Italy
| | - Emiliano di Gennaro
- CNR-SPIN, UOS Napoli , I-80126 Napoli, Italy
- Department of Physics, University of Napoli Federico II , I-80126 Napoli, Italy
| | - Carmela Aruta
- CNR-SPIN, UOS Napoli , I-80126 Napoli, Italy
- Department of Physics, University of Napoli Federico II , I-80126 Napoli, Italy
| | | | | | - Denis Céolin
- Synchrotron SOLEIL , L'Orme des Merisiers, BP 48, Saint Aubin, 91192 Gif sur Yvette, France
| | - Jean-Pascal Rueff
- Synchrotron SOLEIL , L'Orme des Merisiers, BP 48, Saint Aubin, 91192 Gif sur Yvette, France
- Laboratoire de Chimie Physique-Matière et Rayonnement, UPMC Université; Paris 06, CNRS, UMR 7614 , F-75005 Paris, France
| | | | - Chiara Bigi
- CNR-IOM, Laboratorio TASC , I-34149 Trieste, Italy
- Department of Physics, University of Milano , I-20133 Milano, Italy
| | - Pranab Kumar Das
- CNR-IOM, Laboratorio TASC , I-34149 Trieste, Italy
- International Centre for Theoretical Physics (ICTP) , I-34100 Trieste, Italy
| | - Jun Fujii
- CNR-IOM, Laboratorio TASC , I-34149 Trieste, Italy
| | | | | | | | - Giorgio Rossi
- CNR-IOM, Laboratorio TASC , I-34149 Trieste, Italy
- Department of Physics, University of Milano , I-20133 Milano, Italy
| | - Fabio Miletto Granozio
- CNR-SPIN, UOS Napoli , I-80126 Napoli, Italy
- Department of Physics, University of Napoli Federico II , I-80126 Napoli, Italy
| | - Umberto Scotti di Uccio
- CNR-SPIN, UOS Napoli , I-80126 Napoli, Italy
- Department of Physics, University of Napoli Federico II , I-80126 Napoli, Italy
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Vaz DC, Lesne E, Sander A, Naganuma H, Jacquet E, Santamaria J, Barthélémy A, Bibes M. Tuning Up or Down the Critical Thickness in LaAlO 3 /SrTiO 3 through In Situ Deposition of Metal Overlayers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1700486. [PMID: 28505388 DOI: 10.1002/adma.201700486] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 03/28/2017] [Indexed: 06/07/2023]
Abstract
The quasi 2D electron system (q2DES) that forms at the interface between LaAlO3 and SrTiO3 has attracted much attention from the oxide electronics community. One of its hallmark features is the existence of a critical LaAlO3 thickness of 4 unit-cells (uc) for interfacial conductivity to emerge. In this paper, the chemical, electronic, and transport properties of LaAlO3 /SrTiO3 samples capped with different metals grown in a system combining pulsed laser deposition, sputtering, and in situ X-ray photoemission spectroscopy are investigated. The results show that for metals with low work function a q2DES forms at 1-2 uc of LaAlO3 and is accompanied by a partial oxidation of the metal, a phenomenon that affects the q2DES properties and triggers the formation of defects. In contrast, for noble metals, the critical thickness is increased above 4 uc. The results are discussed in terms of a hybrid mechanism that incorporates electrostatic and chemical effects.
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Affiliation(s)
- Diogo Castro Vaz
- Unité Mixte de Physique UMR 137 CNRS/Thales, Université Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - Edouard Lesne
- Unité Mixte de Physique UMR 137 CNRS/Thales, Université Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - Anke Sander
- Unité Mixte de Physique UMR 137 CNRS/Thales, Université Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - Hiroshi Naganuma
- Unité Mixte de Physique UMR 137 CNRS/Thales, Université Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan
| | - Eric Jacquet
- Unité Mixte de Physique UMR 137 CNRS/Thales, Université Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - Jacobo Santamaria
- Unité Mixte de Physique UMR 137 CNRS/Thales, Université Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
- Instituto de Magnetismo Aplicado, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Agnès Barthélémy
- Unité Mixte de Physique UMR 137 CNRS/Thales, Université Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - Manuel Bibes
- Unité Mixte de Physique UMR 137 CNRS/Thales, Université Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
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