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Chatterjee A, Lan Z, Christensen DV, Bauitti F, Morata A, Chavez-Angel E, Sanna S, Castelli IE, Chen Y, Tarancon A, Pryds N. On the thermoelectric properties of Nb-doped SrTiO 3 epitaxial thin films. Phys Chem Chem Phys 2022; 24:3741-3748. [PMID: 35080541 DOI: 10.1039/d1cp03679c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The exploration for thermoelectric thin films of complex oxides such as SrTiO3-based oxides is driven by the need for miniaturized harvesting devices for powering the Internet of Things (IoT). However, there is still not a clear consensus in the literature for the underlying influence of film thickness on thermoelectric properties. Here, we report the fabrication of epitaxial thin films of 6% Nb-doped SrTiO3 on (001) (LaAlO3)0.3(Sr2AlTaO6)0.7 (LSAT) single crystal using pulsed laser deposition (PLD) where the film thickness was varied from 2 nm to 68 nm. The thickness dependence shows a subtle increase of tetragonality of the thin film lattice and a gradual drop of the electrical conductivity, the density of charge carriers, and the thermoelectric Seebeck coefficient as the film thickness decreases. DFT-based calculations show that ∼2.8% increase in tetragonality results in an increased splitting between t2g and eg orbitals to ∼42.3 meV. However, experimentally observed tetragonality for films between 68 to 13 nm is only 0.06%. Hence, the effect of thickness on tetragonality is neglected. We have discussed the decrease of conductivity and the Seebeck coefficient based on the decrease of carriers and change in the scattering mechanism, respectively.
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Affiliation(s)
- Arindom Chatterjee
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs Lyngby, Denmark.
| | - Zhenyun Lan
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs Lyngby, Denmark.
| | | | - Federico Bauitti
- Catalonia Institute for Energy Research (IREC), Jardins de Les Dones de Negre 1, 08930 Sant Adrià Besos, Barcelona, Spain
| | - Alex Morata
- Catalonia Institute for Energy Research (IREC), Jardins de Les Dones de Negre 1, 08930 Sant Adrià Besos, Barcelona, Spain
| | - Emigdio Chavez-Angel
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), and Barcelona Institute of Science and Technology (BIST), Bellaterra-08193, Spain
| | - Simone Sanna
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs Lyngby, Denmark. .,Università degli Studi di Roma Tor Vergata and CNR-SPIN Rome, Department of Civil Engineering and Computer Science, Università di Roma Tor Vergata Dipartimento di Ingegneria Civile e Ingegneria Informatica DICII, Via del Politecnico-1, I - 00133, Roma, Italy
| | - Ivano E Castelli
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs Lyngby, Denmark.
| | - Yunzhong Chen
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs Lyngby, Denmark.
| | - Albert Tarancon
- Catalonia Institute for Energy Research (IREC), Jardins de Les Dones de Negre 1, 08930 Sant Adrià Besos, Barcelona, Spain.,ICREA, 23 Passeig Lluís Companys, Barcelona 08010, Spain
| | - Nini Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs Lyngby, Denmark.
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Effects of small-angle mistilts on dopant visibility in ADF-STEM imaging of nanocrystals. Ultramicroscopy 2017; 177:53-57. [PMID: 28292686 DOI: 10.1016/j.ultramic.2017.03.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 02/03/2017] [Accepted: 03/05/2017] [Indexed: 11/20/2022]
Abstract
Quantitative ADF-STEM imaging paired with image simulations has proven to be a powerful technique for determining the three dimensional location of substitutionally doped atoms in thin films. Expansion of this technique to lightly-doped nanocrystals requires an understanding of the influence of specimen mistilt on dopant visibility due to the difficulty of accurate orientation determination in such systems as well as crystal movement under the beam. In this study, the effects of specimen mistilt on ADF-STEM imaging are evaluated using germanium-doped silicon nanocrystals as model systems. It is shown that dopant visibility is a strong function of specimen mistilt, and the accuracy of specimen orientation is an important factor in the analysis of three-dimensional dopant location, but the sensitivity to mistilt can be weakened by increasing the STEM probe convergence angle and optimizing ADF detector inner angle.
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Rodenbücher C, Luysberg M, Schwedt A, Havel V, Gunkel F, Mayer J, Waser R. Homogeneity and variation of donor doping in Verneuil-grown SrTiO3:Nb single crystals. Sci Rep 2016; 6:32250. [PMID: 27577508 PMCID: PMC5006055 DOI: 10.1038/srep32250] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 08/03/2016] [Indexed: 12/14/2022] Open
Abstract
The homogeneity of Verneuil-grown SrTiO3:Nb crystals was investigated. Due to the fast crystal growth process, inhomogeneities in the donor dopant distribution and variation in the dislocation density are expected to occur. In fact, for some crystals optical studies show variations in the density of Ti(3+) states on the microscale and a cluster-like surface conductivity was reported in tip-induced resistive switching studies. However, our investigations by TEM, EDX mapping, and 3D atom probe reveal that the Nb donors are distributed in a statistically random manner, indicating that there is clearly no inhomogeneity on the macro-, micro-, and nanoscale in high quality Verneuil-grown crystals. In consequence, the electronic transport in the bulk of donor-doped crystals is homogeneous and it is not significantly channelled by extended defects such as dislocations which justifies using this material, for example, as electronically conducting substrate for epitaxial oxide film growth.
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Affiliation(s)
- C. Rodenbücher
- Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-7) and JARA-FIT, 52425 Jülich, Germany
| | - M. Luysberg
- Forschungszentrum Jülich GmbH, Ernst Ruska-Centre (ER-C) for Microscopy and Spectroscopy with Electrons, 52425 Jülich, Germany
| | - A. Schwedt
- RWTH Aachen, Gemeinschaftslabor für Elektronenmikroskopie, 52056 Aachen, Germany
| | - V. Havel
- RWTH Aachen University, Institute of Electronic Materials (IWE2), 52056 Aachen, Germany
| | - F. Gunkel
- Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-7) and JARA-FIT, 52425 Jülich, Germany
- RWTH Aachen University, Institute of Electronic Materials (IWE2), 52056 Aachen, Germany
| | - J. Mayer
- Forschungszentrum Jülich GmbH, Ernst Ruska-Centre (ER-C) for Microscopy and Spectroscopy with Electrons, 52425 Jülich, Germany
- RWTH Aachen, Gemeinschaftslabor für Elektronenmikroskopie, 52056 Aachen, Germany
| | - R. Waser
- Forschungszentrum Jülich GmbH, Peter Grünberg Institute (PGI-7) and JARA-FIT, 52425 Jülich, Germany
- RWTH Aachen University, Institute of Electronic Materials (IWE2), 52056 Aachen, Germany
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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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Cai F, Tang Y, Chen F, Yan Y, Shi W. Enhanced visible-light-driven photocatalytic degradation of tetracycline by Cr3+ doping SrTiO3 cubic nanoparticles. RSC Adv 2015. [DOI: 10.1039/c4ra13821j] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The removal of tetracyclines (TC), the extensively used antibiotics, from the environment has become an important issue.
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Affiliation(s)
- Fanpeng Cai
- School of Biology and Chemical Engineering
- Jiangsu University of Science and Technology
- Zhenjiang
- P. R. China
- School of Chemistry and Chemical Engineering
| | - Yubin Tang
- School of Biology and Chemical Engineering
- Jiangsu University of Science and Technology
- Zhenjiang
- P. R. China
| | - Fangyan Chen
- School of Biology and Chemical Engineering
- Jiangsu University of Science and Technology
- Zhenjiang
- P. R. China
| | - Yan Yan
- School of Chemistry and Chemical Engineering
- Jiangsu University
- Zhenjiang
- P. R. China
| | - Weidong Shi
- School of Chemistry and Chemical Engineering
- Jiangsu University
- Zhenjiang
- P. R. China
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