1
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Pylarinou M, Sakellis E, Tsipas P, Gardelis S, Psycharis V, Dimoulas A, Stergiopoulos T, Likodimos V. Light concentration and electron transfer in plasmonic-photonic Ag,Au modified Mo-BiVO 4 inverse opal photoelectrocatalysts. Nanoscale 2024. [PMID: 38739078 DOI: 10.1039/d3nr06407g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
Plasmonic photocatalysis based on metal-semiconductor heterojunctions is considered a key strategy to evade the inherent limitations of poor light harvesting and charge separation of semiconductor photocatalysts. It can be profitably combined with three-dimensional photonic crystals (PCs) that offer an ideal scaffold for loading plasmonic nanoparticles and a unique architecture to intensify photon capture. In this work, Mo-doped BiVO4 inverse opals were applied as visible light-responsive photonic hosts of Ag and/or Au plasmonic nanoparticles in order to exploit the synergy of plasmonic and photonic amplification effects with interfacial charge transfer for the photoelectrocatalytic degradation of recalcitrant pharmaceutical contaminants under visible light. Photoelectrochemical evaluation indicated a major contribution from hot spot-assisted local field enhancement, most pronounced for Ag/Mo-BiVO4 PCs due to the spectral overlap of the localized surface plasmon resonance with the electronic absorption and blue-edge slow photon region of Mo-BiVO4 PCs, in contrast to weak plasmonic sensitization effects for the Au-modified PCs. The diverse band alignment at the metal-semiconductor interfaces resulted in the enhanced photoelectrocatalytic degradation of tetracycline broad spectrum antibiotic by Ag/Mo-BiVO4 and the refractory ibuprofen drug by (Ag,Au)/Mo-BiVO4, attributed to the enhanced charge separation by electron transfer toward Ag nanoparticles. Combination of visible light activated semiconductor PCs and plasmonic nanoparticles with suitable band alignment and photonic band gap may provide a versatile approach for the rational design of efficient plasmonic-photonic photoeletrocatalysts.
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Affiliation(s)
- Martha Pylarinou
- Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, University Campus, 15784, Greece.
| | - Elias Sakellis
- Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, University Campus, 15784, Greece.
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", 15341 Agia Paraskevi, Athens, Greece
| | - Polychronis Tsipas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", 15341 Agia Paraskevi, Athens, Greece
| | - Spiros Gardelis
- Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, University Campus, 15784, Greece.
| | - Vassilis Psycharis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", 15341 Agia Paraskevi, Athens, Greece
| | - Athanasios Dimoulas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", 15341 Agia Paraskevi, Athens, Greece
| | - Thomas Stergiopoulos
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", 15341 Agia Paraskevi, Athens, Greece
| | - Vlassis Likodimos
- Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, University Campus, 15784, Greece.
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2
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Longo E, Locatelli L, Tsipas P, Lintzeris A, Dimoulas A, Fanciulli M, Longo M, Mantovan R. Exploiting the Close-to-Dirac Point Shift of the Fermi Level in the Sb 2Te 3/Bi 2Te 3 Topological Insulator Heterostructure for Spin-Charge Conversion. ACS Appl Mater Interfaces 2023; 15:50237-50245. [PMID: 37862590 PMCID: PMC10623560 DOI: 10.1021/acsami.3c08830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 09/28/2023] [Accepted: 10/02/2023] [Indexed: 10/22/2023]
Abstract
Properly tuning the Fermi level position in topological insulators is of vital importance to tailor their spin-polarized electronic transport and to improve the efficiency of any functional device based on them. Here, we report the full in situ metal organic chemical vapor deposition (MOCVD) and study of a highly crystalline Bi2Te3/Sb2Te3 topological insulator heterostructure on top of large area (4″) Si(111) substrates. The bottom Sb2Te3 layer serves as an ideal seed layer for the growth of highly crystalline Bi2Te3 on top, also inducing a remarkable shift of the Fermi level to place it very close to the Dirac point, as visualized by angle-resolved photoemission spectroscopy. To exploit such ideal topologically protected surface states, we fabricate the simple spin-charge converter Si(111)/Sb2Te3/Bi2Te3/Au/Co/Au and probe the spin-charge conversion (SCC) by spin pumping ferromagnetic resonance. A large SCC is measured at room temperature and is interpreted within the inverse Edelstein effect, thus resulting in a conversion efficiency of λIEEE ∼ 0.44 nm. Our results demonstrate the successful tuning of the surface Fermi level of Bi2Te3 when grown on top of Sb2Te3 with a full in situ MOCVD process, which is highly interesting in view of its future technology transfer.
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Affiliation(s)
- Emanuele Longo
- CNR-IMM, Unit of Agrate Brianza, Via C. Olivetti 2, Agrate
Brianza 20864, Italy
| | - Lorenzo Locatelli
- CNR-IMM, Unit of Agrate Brianza, Via C. Olivetti 2, Agrate
Brianza 20864, Italy
| | - Polychronis Tsipas
- National
Centre for Scientific Research “Demokritos”, Institute of Nanoscience and Nanotechnology, Agia Paraskevi 15341, Athens, Greece
| | - Akylas Lintzeris
- National
Centre for Scientific Research “Demokritos”, Institute of Nanoscience and Nanotechnology, Agia Paraskevi 15341, Athens, Greece
- Department
of Physics, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Athens 10682, Greece
| | - Athanasios Dimoulas
- National
Centre for Scientific Research “Demokritos”, Institute of Nanoscience and Nanotechnology, Agia Paraskevi 15341, Athens, Greece
| | - Marco Fanciulli
- Department
of Material Science, University of Milano
Bicocca, Via R. Cozzi 55, Milan 20125, Italy
| | - Massimo Longo
- CNR-IMM, Unit of Agrate Brianza, Via C. Olivetti 2, Agrate
Brianza 20864, Italy
- Department
of Chemical Science and Technologies, University
of Rome Tor Vergata, Via della Ricerca Scientifica, Rome 100133, Italy
| | - Roberto Mantovan
- CNR-IMM, Unit of Agrate Brianza, Via C. Olivetti 2, Agrate
Brianza 20864, Italy
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3
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Loukopoulos S, Sakellis E, Kostakis MG, Gerokonstantis DT, Tsipas P, Gardelis S, Kontos AG, Katsaros FK, Sideratou Z, Romanos GE, Dimoulas A, Thomaidis NS, Likodimos V. Co-assembled MoS 2-TiO 2 Inverse Opal Photocatalysts for Visible Light-Activated Pharmaceutical Photodegradation. ACS Omega 2023; 8:33639-33650. [PMID: 37744818 PMCID: PMC10515384 DOI: 10.1021/acsomega.3c03881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 08/18/2023] [Indexed: 09/26/2023]
Abstract
Heterostructured photocatalytic materials in the form of photonic crystals have been attracting attention for their unique light harvesting ability that can be ideally combined with judicious compositional modifications toward the development of visible light-activated (VLA) photonic catalysts, though practical environmental applications, such as the degradation of pharmaceutical emerging contaminants, have been rarely reported. Herein, heterostructured MoS2-TiO2 inverse opal films are introduced as highly active immobilized photocatalysts for the VLA degradation of tetracycline and ciprofloxacin broad-spectrum antibiotics as well as salicylic acid. A single-step co-assembly method was implemented for the challenging incorporation of MoS2 nanosheets into the nanocrystalline inverse opal walls. Compositional tuning and photonic band gap engineering of the MoS2-TiO2 photonic films showed that integration of low amounts of MoS2 nanosheets in the inverse opal framework maintains intact the periodic macropore structure and enhances the available surface area, resulting in efficient VLA antibiotic degradation far beyond the performance of benchmark TiO2 films. The combination of broadband MoS2 visible light absorption and photonic-assisted light trapping together with the enhanced charge separation that enables the generation of reactive oxygen species via firm interfacial coupling between MoS2 nanosheets and TiO2 nanoparticles is concluded as a competent approach for pharmaceutical abatement in water bodies.
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Affiliation(s)
- Stelios Loukopoulos
- Section
of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, University Campus, Zografou, Athens 15784, Greece
| | - Elias Sakellis
- Institute
of Nanoscience and Nanotechnology, National
Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens 15341, Greece
| | - Marios G. Kostakis
- Laboratory
of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, University Campus, Zografou, Athens 15771, Greece
| | - Dimitrios-Triantafyllos Gerokonstantis
- Laboratory
of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, University Campus, Zografou, Athens 15771, Greece
| | - Polychronis Tsipas
- Institute
of Nanoscience and Nanotechnology, National
Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens 15341, Greece
| | - Spiros Gardelis
- Section
of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, University Campus, Zografou, Athens 15784, Greece
| | - Athanassios G. Kontos
- Institute
of Nanoscience and Nanotechnology, National
Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens 15341, Greece
- Department
of Physics, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Athens 15780, Greece
| | - Fotis K. Katsaros
- Institute
of Nanoscience and Nanotechnology, National
Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens 15341, Greece
| | - Zili Sideratou
- Institute
of Nanoscience and Nanotechnology, National
Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens 15341, Greece
| | - George Em. Romanos
- Institute
of Nanoscience and Nanotechnology, National
Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens 15341, Greece
| | - Athanasios Dimoulas
- Institute
of Nanoscience and Nanotechnology, National
Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens 15341, Greece
| | - Nikolaos S. Thomaidis
- Laboratory
of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, University Campus, Zografou, Athens 15771, Greece
| | - Vlassis Likodimos
- Section
of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, University Campus, Zografou, Athens 15784, Greece
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4
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Chavez-Angel E, Tsipas P, Xiao P, Ahmadi MT, Daaoub AHS, Sadeghi H, Sotomayor Torres CM, Dimoulas A, Sachat AE. Engineering Heat Transport Across Epitaxial Lattice-Mismatched van der Waals Heterointerfaces. Nano Lett 2023; 23:6883-6891. [PMID: 37467035 PMCID: PMC10416569 DOI: 10.1021/acs.nanolett.3c01280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/27/2023] [Indexed: 07/20/2023]
Abstract
Artificially engineered 2D materials offer unique physical properties for thermal management, surpassing naturally occurring materials. Here, using van der Waals epitaxy, we demonstrate the ability to engineer extremely insulating thermal metamaterials based on atomically thin lattice-mismatched Bi2Se3/MoSe2 superlattices and graphene/PdSe2 heterostructures with exceptional thermal resistances (70-202 m2 K/GW) and ultralow cross-plane thermal conductivities (0.012-0.07 W/mK) at room temperature, comparable to those of amorphous materials. Experimental data obtained using frequency-domain thermoreflectance and low-frequency Raman spectroscopy, supported by tight-binding phonon calculations, reveal the impact of lattice mismatch, phonon-interface scattering, size effects, temperature, and interface thermal resistance on cross-plane heat dissipation, uncovering different thermal transport regimes and the dominant role of long-wavelength phonons. Our findings provide essential insights into emerging synthesis and thermal characterization methods and valuable guidance for the development of large-area heteroepitaxial van der Waals films of dissimilar materials with tailored thermal transport characteristics.
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Affiliation(s)
- Emigdio Chavez-Angel
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona 08193, Spain
| | - Polychronis Tsipas
- Institute
of Nanoscience and Nanotechnology, National
Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens 15341, Greece
| | - Peng Xiao
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona 08193, Spain
| | | | | | - Hatef Sadeghi
- School
of Engineering, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Clivia M. Sotomayor Torres
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona 08193, Spain
- ICREA, Passeig Lluis Companys 23, Barcelona 08010, Spain
| | - Athanasios Dimoulas
- Institute
of Nanoscience and Nanotechnology, National
Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens 15341, Greece
| | - Alexandros El Sachat
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona 08193, Spain
- Institute
of Nanoscience and Nanotechnology, National
Center for Scientific Research “Demokritos”, Agia Paraskevi, Athens 15341, Greece
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5
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Georgopoulou-Kotsaki E, Pappas P, Lintzeris A, Tsipas P, Fragkos S, Markou A, Felser C, Longo E, Fanciulli M, Mantovan R, Mahfouzi F, Kioussis N, Dimoulas A. Significant enhancement of ferromagnetism above room temperature in epitaxial 2D van der Waals ferromagnet Fe 5-δGeTe 2/Bi 2Te 3 heterostructures. Nanoscale 2023; 15:2223-2233. [PMID: 36625389 DOI: 10.1039/d2nr04820e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Two-dimensional (2D) van der Waals (vdW) ferromagnetic metals FexGeTe2 with x = 3-5 have raised significant interest in the scientific community. Fe5GeTe2 shows prospects for spintronic applications since the Curie temperature Tc has been reported near or higher than 300 K. In the present work, epitaxial Fe5-δGeTe2 (FGT) heterostructures were grown by Molecular Beam Epitaxy (MBE) on insulating crystalline substrates. The FGT films were combined with Bi2Te3 topological insulator (TI) aiming to investigate the possible beneficial effect of the TI on the magnetic properties of FGT. FGT/Bi2Te3 films were compared to FGT capped only with AlOx to prevent oxidation. SQUID and MOKE measurements revealed that the growth of Bi2Te3 TI on FGT films significantly enhances the saturation magnetization of FGT as well as the Tc well above room temperature (RT) reaching record values of 570 K. First-principles calculations predict a shift of the Fermi level and an associated enhancement of the majority spin (primarily) as well as the total density of states at the Fermi level suggesting that effective doping of FGT from Bi2Te3 could explain the enhancement of ferromagnetism in FGT. It is also predicted that strain induced stabilization of a high magnetic moment phase in FGT/Bi2Te3 could be an alternative explanation of magnetization and Tc enhancement. Ferromagnetic resonance measurements evidence an enhanced broadening in the FGT/Bi2Te3 heterostructure when compared to FGT. We obtain a large spin mixing conductance of g↑↓eff = 4.4 × 1020 m-2, which demonstrates the great potential of FGT/Bi2Te3 systems for spin-charge conversion applications at room temperature.
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Affiliation(s)
- E Georgopoulou-Kotsaki
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
- Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, 15784, Athens, Greece
| | - P Pappas
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
| | - A Lintzeris
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
- Department of Physics, National Technical University of Athens, School of Applied Mathematical and Physical Sciences, 15780, Athens, Greece
| | - P Tsipas
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
| | - S Fragkos
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
- Department of Mechanical Engineering, University of West Attica, 12241 Athens, Greece
| | - A Markou
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - C Felser
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - E Longo
- Institute for Microelectronics and Microsystems, CNR-IMM Unit of Agrate Brianza, Via C. Olivetti 2, 20864 Agrate Brianza, Italy
| | - M Fanciulli
- Department of Material Science, University of Milano Bicocca, Via R. Cozzi 55, Milan 20125, Italy
| | - R Mantovan
- Institute for Microelectronics and Microsystems, CNR-IMM Unit of Agrate Brianza, Via C. Olivetti 2, 20864 Agrate Brianza, Italy
| | - F Mahfouzi
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330-8268, USA
| | - N Kioussis
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA 91330-8268, USA
| | - A Dimoulas
- National Centre for Scientific Research "Demokritos", Institute of Nanoscience and Nanotechnology, Agia Paraskevi, 15341, Athens, Greece.
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6
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Gkini K, Orfanoudakis S, Tsipas P, Skoulikidou MC, Dimoulas A, Falaras P, Konstantakou M, Stergiopoulos T. ZrCl4 for energy level alignment at the perovskite/TiO2 interface. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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7
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Fakharuddin A, Armadorou K, Zorba LP, Tountas M, Seewald T, Soultati A, Tsipas P, Schütz ER, Tzoganakis N, Panagiotakis S, Yannakopoulou K, Dimoulas A, Psycharis V, Kymakis E, Yusoff ARBM, Aidinis K, Schmidt‐Mende L, Vougioukalakis GC, Nazeeruddin MK, Vasilopoulou M. A triethyleneglycol
C60
mono‐adduct derivative for efficient electron transport in inverted perovskite solar cells. CHINESE J CHEM 2022. [DOI: 10.1002/cjoc.202200542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Konstantina‐Kalliopi Armadorou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi 15341 Athens Greece
- Department of Chemistry National and Kapodistrian University of Athens 15771 Athens Greece
| | - Leandros P. Zorba
- Department of Chemistry National and Kapodistrian University of Athens 15771 Athens Greece
| | - Marinos Tountas
- Department of Electrical & Computer Engineering Hellenic Mediterranean University, Estavromenos, Heraklion GR‐71410 Crete Greece
| | - Tobias Seewald
- Department of Physics University of Konstanz 78457 Konstanz Germany
| | - Anastasia Soultati
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi 15341 Athens Greece
| | - Polychronis Tsipas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi 15341 Athens Greece
| | - Emilia R. Schütz
- Department of Physics University of Konstanz 78457 Konstanz Germany
| | - Nikolaos Tzoganakis
- Department of Electrical & Computer Engineering Hellenic Mediterranean University, Estavromenos, Heraklion GR‐71410 Crete Greece
| | - Stylianos Panagiotakis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi 15341 Athens Greece
| | - Konstantina Yannakopoulou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi 15341 Athens Greece
| | - Athanasios Dimoulas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi 15341 Athens Greece
| | - Vassilis Psycharis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi 15341 Athens Greece
| | - Emmanuel Kymakis
- Department of Electrical & Computer Engineering Hellenic Mediterranean University, Estavromenos, Heraklion GR‐71410 Crete Greece
| | - Abd Rashid bin Mohd Yusoff
- Department of Chemical Engineering Pohang University of Science and Technology (POSTECH) Pohang Gyeongbuk 37673 Republic of Korea
| | - Konstantinos Aidinis
- Department of Electrical and Computer Engineering Ajman University P.O. Box 346 Ajman United Arab Emirates
- Center of Medical and Bio‐allied Health Sciences Research Ajman United Arab Emirates
| | | | | | - Mohammad Khaja Nazeeruddin
- Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL) CH‐1951 Rue de l'Industrie 17 Sion Switzerland
| | - Maria Vasilopoulou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi 15341 Athens Greece
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8
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Pylarinou M, Toumazatou A, Sakellis E, Xenogiannopoulou E, Gardelis S, Boukos N, Dimoulas A, Likodimos V. Visible Light Trapping against Charge Recombination in FeO x-TiO 2 Photonic Crystal Photocatalysts. Materials (Basel) 2021; 14:7117. [PMID: 34885271 PMCID: PMC8658129 DOI: 10.3390/ma14237117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/17/2021] [Accepted: 11/19/2021] [Indexed: 11/17/2022]
Abstract
Tailoring metal oxide photocatalysts in the form of heterostructured photonic crystals has spurred particular interest as an advanced route to simultaneously improve harnessing of solar light and charge separation relying on the combined effect of light trapping by macroporous periodic structures and compositional materials' modifications. In this work, surface deposition of FeOx nanoclusters on TiO2 photonic crystals is investigated to explore the interplay of slow-photon amplification, visible light absorption, and charge separation in FeOx-TiO2 photocatalytic films. Photonic bandgap engineered TiO2 inverse opals deposited by the convective evaporation-induced co-assembly method were surface modified by successive chemisorption-calcination cycles using Fe(III) acetylacetonate, which allowed the controlled variation of FeOx loading on the photonic films. Low amounts of FeOx nanoclusters on the TiO2 inverse opals resulted in diameter-selective improvements of photocatalytic performance on salicylic acid degradation and photocurrent density under visible light, surpassing similarly modified P25 films. The observed enhancement was related to the combination of optimal light trapping and charge separation induced by the FeOx-TiO2 interfacial coupling. However, an increase of the FeOx loading resulted in severe performance deterioration, particularly prominent under UV-Vis light, attributed to persistent surface recombination via diverse defect d-states.
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Affiliation(s)
- Martha Pylarinou
- Section of Condensed Matter Physics, Department of Physics, University Campus, National and Kapodistrian University of Athens, 15784 Athens, Greece; (M.P.); (A.T.); (S.G.)
| | - Alexia Toumazatou
- Section of Condensed Matter Physics, Department of Physics, University Campus, National and Kapodistrian University of Athens, 15784 Athens, Greece; (M.P.); (A.T.); (S.G.)
| | - Elias Sakellis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, 15341 Agia Paraskevi, Greece; (E.S.); (E.X.); (N.B.); (A.D.)
| | - Evangelia Xenogiannopoulou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, 15341 Agia Paraskevi, Greece; (E.S.); (E.X.); (N.B.); (A.D.)
| | - Spiros Gardelis
- Section of Condensed Matter Physics, Department of Physics, University Campus, National and Kapodistrian University of Athens, 15784 Athens, Greece; (M.P.); (A.T.); (S.G.)
| | - Nikos Boukos
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, 15341 Agia Paraskevi, Greece; (E.S.); (E.X.); (N.B.); (A.D.)
| | - Athanasios Dimoulas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, 15341 Agia Paraskevi, Greece; (E.S.); (E.X.); (N.B.); (A.D.)
| | - Vlassis Likodimos
- Section of Condensed Matter Physics, Department of Physics, University Campus, National and Kapodistrian University of Athens, 15784 Athens, Greece; (M.P.); (A.T.); (S.G.)
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9
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Xiao P, Chavez-Angel E, Chaitoglou S, Sledzinska M, Dimoulas A, Sotomayor Torres CM, El Sachat A. Anisotropic Thermal Conductivity of Crystalline Layered SnSe 2. Nano Lett 2021; 21:9172-9179. [PMID: 34710326 DOI: 10.1021/acs.nanolett.1c03018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The degree of thermal anisotropy affects critically key device-relevant properties of layered two-dimensional materials. Here, we systematically study the in-plane and cross-plane thermal conductivity of crystalline SnSe2 films of varying thickness (16-190 nm) and uncover a thickness-independent thermal conductivity anisotropy ratio of about ∼8.4. Experimental data obtained using Raman thermometry and frequency domain thermoreflectance showed that the in-plane and cross-plane thermal conductivities monotonically decrease by a factor of 2.5 with decreasing film thickness compared to the bulk values. Moreover, we find that the temperature-dependence of the in-plane component gradually decreases as the film becomes thinner, and in the range from 300 to 473 K it drops by more than a factor of 2. Using the mean free path reconstruction method, we found that phonons with MFP ranging from ∼1 to 53 and from 1 to 30 nm contribute to 50% of the total in-plane and cross-plane thermal conductivity, respectively.
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Affiliation(s)
- Peng Xiao
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Departamento de Física, Universidad Autónoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Emigdio Chavez-Angel
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | | | - Marianna Sledzinska
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | | | - Clivia M Sotomayor Torres
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- ICREA, Passeig Lluis Companys 23, 08010 Barcelona, Spain
| | - Alexandros El Sachat
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
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10
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Xenogiannopoulou E, Tsoutsou D, Tsipas P, Fragkos S, Chaitoglou S, Kelaidis N, Dimoulas A. Ultrathin epitaxial Bi film growth on 2D HfTe 2template. Nanotechnology 2021; 33:015701. [PMID: 34610589 DOI: 10.1088/1361-6528/ac2d08] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/05/2021] [Indexed: 06/13/2023]
Abstract
Among ultrathin monoelemental two-dimensional (2D) materials, bismuthene, the single layer of heavier group-VΑ element bismuth (Bi), has been predicted to have large non trivial gap. Here, we demonstrate the growth of Bi films by molecular beam epitaxy on 2D-HfTe2template. At the initial stage of Bi deposition (1-2 bilayers, BL), both the pseudocubic Bi(110) and the hexagonal Bi(111) phases are formed. When reaching 3 BL Bi, a transformation to pure hexagonal Bi(111) occurs. The electronic band structure of 3 BL Bi(111) films was measured by angle-resolved photoemission spectroscopy showing very good matching with the density functional theory band structure calculations of 3 BL free standing Bi(111). The grown Bi(111) thin film was capped with a protective Al2O3layer and its stability under ambient conditions, necessary for practical applications and device fabrication, was confirmed by x-ray photoelectron spectroscopy and Raman spectroscopy.
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Affiliation(s)
- Evangelia Xenogiannopoulou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research 'Demokritos', 15310, Athens, Greece
| | - Dimitra Tsoutsou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research 'Demokritos', 15310, Athens, Greece
| | - Polychronis Tsipas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research 'Demokritos', 15310, Athens, Greece
| | - Sotirios Fragkos
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research 'Demokritos', 15310, Athens, Greece
- Department of Mechanical Engineering, University of West Attica, 12244, Athens, Greece
| | - Stefanos Chaitoglou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research 'Demokritos', 15310, Athens, Greece
| | - Nikolaos Kelaidis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research 'Demokritos', 15310, Athens, Greece
| | - Athanasios Dimoulas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research 'Demokritos', 15310, Athens, Greece
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11
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Apostolaki MA, Toumazatou A, Antoniadou M, Sakellis E, Xenogiannopoulou E, Gardelis S, Boukos N, Falaras P, Dimoulas A, Likodimos V. Graphene Quantum Dot-TiO 2 Photonic Crystal Films for Photocatalytic Applications. Nanomaterials (Basel) 2020; 10:nano10122566. [PMID: 33371303 PMCID: PMC7766274 DOI: 10.3390/nano10122566] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/17/2020] [Accepted: 12/18/2020] [Indexed: 11/25/2022]
Abstract
Photonic crystal structuring has emerged as an advanced method to enhance solar light harvesting by metal oxide photocatalysts along with rational compositional modifications of the materials’ properties. In this work, surface functionalization of TiO2 photonic crystals by blue luminescent graphene quantum dots (GQDs), n–π* band at ca. 350 nm, is demonstrated as a facile, environmental benign method to promote photocatalytic activity by the combination of slow photon-assisted light trapping with GQD-TiO2 interfacial electron transfer. TiO2 inverse opal films fabricated by the co-assembly of polymer colloidal spheres with a hydrolyzed titania precursor were post-modified by impregnation in aqueous GQDs suspension without any structural distortion. Photonic band gap engineering by varying the inverse opal macropore size resulted in selective performance enhancement for both salicylic acid photocatalytic degradation and photocurrent generation under UV–VIS and visible light, when red-edge slow photons overlapped with the composite’s absorption edge, whereas stop band reflection was attenuated by the strong UVA absorbance of the GQD-TiO2 photonic films. Photoelectrochemical and photoluminescence measurements indicated that the observed improvement, which surpassed similarly modified benchmark mesoporous P25 TiO2 films, was further assisted by GQDs electron acceptor action and visible light activation to a lesser extent, leading to highly efficient photocatalytic films.
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Affiliation(s)
- Maria-Athina Apostolaki
- Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, GR-15784 Athens, Greece; (M.-A.A.); (A.T.); (S.G.)
| | - Alexia Toumazatou
- Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, GR-15784 Athens, Greece; (M.-A.A.); (A.T.); (S.G.)
| | - Maria Antoniadou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, Agia Paraskevi, 15341 Athens, Greece; (M.A.); (E.S.); (E.X.); (N.B.); (P.F.); (A.D.)
| | - Elias Sakellis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, Agia Paraskevi, 15341 Athens, Greece; (M.A.); (E.S.); (E.X.); (N.B.); (P.F.); (A.D.)
| | - Evangelia Xenogiannopoulou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, Agia Paraskevi, 15341 Athens, Greece; (M.A.); (E.S.); (E.X.); (N.B.); (P.F.); (A.D.)
| | - Spiros Gardelis
- Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, GR-15784 Athens, Greece; (M.-A.A.); (A.T.); (S.G.)
| | - Nikos Boukos
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, Agia Paraskevi, 15341 Athens, Greece; (M.A.); (E.S.); (E.X.); (N.B.); (P.F.); (A.D.)
| | - Polycarpos Falaras
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, Agia Paraskevi, 15341 Athens, Greece; (M.A.); (E.S.); (E.X.); (N.B.); (P.F.); (A.D.)
| | - Athanasios Dimoulas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, Agia Paraskevi, 15341 Athens, Greece; (M.A.); (E.S.); (E.X.); (N.B.); (P.F.); (A.D.)
| | - Vlassis Likodimos
- Section of Condensed Matter Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, GR-15784 Athens, Greece; (M.-A.A.); (A.T.); (S.G.)
- Correspondence: ; Tel.: +30-2107276824
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12
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Chaitoglou S, Giannakopoulou T, Tsoutsou D, Vavouliotis A, Trapalis C, Dimoulas A. Direct versus reverse vertical two-dimensional Mo 2C/graphene heterostructures for enhanced hydrogen evolution reaction electrocatalysis. Nanotechnology 2019; 30:415404. [PMID: 31295736 DOI: 10.1088/1361-6528/ab3155] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Mo2C/graphene heterostructures prepared by chemical vapor deposition have demonstrated excellent electrocatalytic activity in a hydrogen evolution reaction (HER). This is attributed to the high catalytic activity of Mo2C while the high electrical conductivity of graphene facilitates charge transfer. In the as-grown direct vertical order, graphene is placed above the Mo2C film. This reduces the catalytic activity of the heterostructure, since graphene in chemically inert. Here, a simple transfer method is proposed that results in the reverse order deposition of the heterostructure on the electrode. This method places graphene at the interface between Mo2C and the electrode, enhancing charge transfer between them, which results in an overpotential of 440 mV at 10 mA cm-2 and corresponds to ∼65 mV overpotential reduction as compared to the direct heterostructure. At the same time, when a direct Cu/Mo2C/graphene junction with a Cu catalyst substrate is used as a working electrode, the improvement of the heterostructure HER activity is observed which is manifested in an overpotential of 275 mV at 10 mA cm-2 with a correspondent ∼230 mV reduction. All above performances are accompanied with excellent endurance.
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Affiliation(s)
- Stefanos Chaitoglou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research 'DEMOKRITOS', 15310, Athens, Greece
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13
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Diamantopoulou A, Sakellis E, Gardelis S, Tsoutsou D, Glenis S, Boukos N, Dimoulas A, Likodimos V. Advanced Photocatalysts Based on Reduced Nanographene Oxide-TiO 2 Photonic Crystal Films. Materials (Basel) 2019; 12:ma12162518. [PMID: 31394874 PMCID: PMC6720929 DOI: 10.3390/ma12162518] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 07/31/2019] [Accepted: 08/05/2019] [Indexed: 02/05/2023]
Abstract
Surface functionalization of TiO2 inverse opals by graphene oxide nanocolloids (nanoGO) presents a promising modification for the development of advanced photocatalysts that combine slow photon-assisted light harvesting, surface area, and mass transport of macroporous photonic structures with the enhanced adsorption capability, surface reactivity, and charge separation of GO nanosheets. In this work, post-thermal reduction of nanoGO–TiO2 inverse opals was investigated in order to explore the role of interfacial electron transfer vs. pollutant adsorption and improve their photocatalytic activity. Photonic band gap-engineered TiO2 inverse opals were fabricated by the coassembly technique and were functionalized by GO nanosheets and reduced under He at 200 and 500 °C. Comparative performance evaluation of the nanoGO–TiO2 films on methylene blue photodegradation under UV-VIS and visible light showed that thermal reduction at 200 °C, in synergy with slow photon effects, improved the photocatalytic reaction rate despite the loss of nanoGO and oxygen functional groups, pointing to enhanced charge separation. This was further supported by photoluminescence spectroscopy and salicylic acid UV-VIS photodegradation, where, in the absence of photonic effects, the photocatalytic activity increased, confirming that fine-tuning of interfacial coupling between TiO2 and reduced nanoGO is a key factor for the development of highly efficient photocatalytic films.
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Affiliation(s)
- Angeliki Diamantopoulou
- Section of Solid State Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, 15784 Ilissia, Greece
| | - Elias Sakellis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", 15310 Agia Paraskevi, Greece
| | - Spiros Gardelis
- Section of Solid State Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, 15784 Ilissia, Greece
| | - Dimitra Tsoutsou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", 15310 Agia Paraskevi, Greece
| | - Spyridon Glenis
- Section of Solid State Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, 15784 Ilissia, Greece
| | - Nikolaos Boukos
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", 15310 Agia Paraskevi, Greece
| | - Athanasios Dimoulas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "Demokritos", 15310 Agia Paraskevi, Greece
| | - Vlassis Likodimos
- Section of Solid State Physics, Department of Physics, National and Kapodistrian University of Athens, Panepistimiopolis, 15784 Ilissia, Greece.
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14
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Dimitrakellis P, Smyrnakis A, Constantoudis V, Tsoutsou D, Dimoulas A, Gogolides E. Erratum to “Atmospheric pressure plasma directed assembly during photoresist removal: A new route to micro and nano pattern formation” [Micro and Nano Engineering Vol. 3 (2019) 15–21]. Micro and Nano Engineering 2019. [DOI: 10.1016/j.mne.2019.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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15
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Dimitrakellis P, Smyrnakis A, Constantoudis V, Tsoutsou D, Dimoulas A, Gogolides E. Atmospheric pressure plasma directed assembly during photoresist removal: A new route to micro and nano pattern formation. Micro and Nano Engineering 2019. [DOI: 10.1016/j.mne.2019.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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16
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Chaitoglou S, Giannakopoulou T, Speliotis T, Vavouliotis A, Trapalis C, Dimoulas A. Mo 2C/graphene heterostructures: low temperature chemical vapor deposition on liquid bimetallic Sn-Cu and hydrogen evolution reaction electrocatalytic properties. Nanotechnology 2019; 30:125401. [PMID: 30566921 DOI: 10.1088/1361-6528/aaf9e8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Thin 2D Mo2C/graphene vertical heterostructures have attracted significant attention due to their potential application as electrodes in the hydrogen evolution reaction (HER) and energy storage. A common drawback in the chemical vapor deposition synthesis of these structures is the demand for high temperature growth, which should be higher than the melting temperature of the metal catalyst. The most common metallic catalyst is Cu, which has a melting temperature of 1084 °C. Here, we report the growth of thin, ∼200 nm in thickness, semitransparent micrometer-sized Mo2C domains and Mo2C/graphene heterostructures at lower temperatures using liquid Sn-Cu alloys. No Sn-associated defects are observed, making the alloy an appealing growth substrate. Raman spectroscopy reveals the vertical interaction between graphene and Mo2C, as shown by the variation in the strain of the graphene film. The results demonstrate the capability to grow continuous nanometer-thin Mo2C films at temperatures as low as 880 °C, without sacrificing the growth rate. Mo2C films are proven to be efficient electrocatalysts for the HER. Moreover, we demonstrate the beneficial role of graphene overgrown on Mo2C in reducing the HER overpotential values, which is attributed to more efficient charge transfer kinetics, compared to pure Mo2C films.
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Affiliation(s)
- Stefanos Chaitoglou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research 'DEMOKRITOS', 15310, Athens, Greece
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17
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Tsipas P, Tsoutsou D, Fragkos S, Sant R, Alvarez C, Okuno H, Renaud G, Alcotte R, Baron T, Dimoulas A. Massless Dirac Fermions in ZrTe 2 Semimetal Grown on InAs(111) by van der Waals Epitaxy. ACS Nano 2018; 12:1696-1703. [PMID: 29314824 DOI: 10.1021/acsnano.7b08350] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Single and few layers of the two-dimensional (2D) semimetal ZrTe2 are grown by molecular beam epitaxy on InAs(111)/Si(111) substrates. Excellent rotational commensurability, van der Waals gap at the interface and moiré pattern are observed indicating good registry between the ZrTe2 epilayer and the substrate through weak van der Waals forces. The electronic band structure imaged by angle resolved photoelectron spectroscopy shows that valence and conduction bands cross at the Fermi level exhibiting abrupt linear dispersions. The latter indicates massless Dirac Fermions which are maintained down to the 2D limit suggesting that single-layer ZrTe2 could be considered as the electronic analogue of graphene.
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Affiliation(s)
- Polychronis Tsipas
- National Center for Scientific Research "Demokritos" , 15310 Athens, Greece
| | - Dimitra Tsoutsou
- National Center for Scientific Research "Demokritos" , 15310 Athens, Greece
| | - Sotirios Fragkos
- National Center for Scientific Research "Demokritos" , 15310 Athens, Greece
| | - Roberto Sant
- University Grenoble Alpes , 38400 Grenoble, France
- Néel Institute, CNRS , 38042 Grenoble, France
| | - Carlos Alvarez
- University Grenoble Alpes , 38400 Grenoble, France
- CEA/INAC-MEM , F-38054 Grenoble Cedex 9, France
| | - Hanako Okuno
- University Grenoble Alpes , 38400 Grenoble, France
- CEA/INAC-MEM , F-38054 Grenoble Cedex 9, France
| | - Gilles Renaud
- University Grenoble Alpes , 38400 Grenoble, France
- CEA/INAC-MEM , F-38054 Grenoble Cedex 9, France
| | - Reynald Alcotte
- Universite Grenoble Alpes, CNRS, CEA/Leti Minatec, LTM , F-38054 Grenoble Cedex 9, France
| | - Thierry Baron
- Universite Grenoble Alpes, CNRS, CEA/Leti Minatec, LTM , F-38054 Grenoble Cedex 9, France
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18
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Aretouli KE, Tsoutsou D, Tsipas P, Marquez-Velasco J, Aminalragia Giamini S, Kelaidis N, Psycharis V, Dimoulas A. Epitaxial 2D SnSe2/ 2D WSe2 van der Waals Heterostructures. ACS Appl Mater Interfaces 2016; 8:23222-23229. [PMID: 27537619 DOI: 10.1021/acsami.6b02933] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
van der Waals heterostructures of 2D semiconductor materials can be used to realize a number of (opto)electronic devices including tunneling field effect devices (TFETs). It is shown in this work that high quality SnSe2/WSe2 vdW heterostructure can be grown by molecular beam epitaxy on AlN(0001)/Si(111) substrates using a Bi2Se3 buffer layer. A valence band offset of 0.8 eV matches the energy gap of SnSe2 in such a way that the VB edge of WSe2 and the CB edge of SnSe2 are lined up, making this materials combination suitable for (nearly) broken gap TFETs.
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Affiliation(s)
- Kleopatra Emmanouil Aretouli
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS" , 15310, Athens, Greece
- University of Athens , Department of Physics, Section of Solid State Physics, 15684 Athens, Greece
| | - Dimitra Tsoutsou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS" , 15310, Athens, Greece
| | - Polychronis Tsipas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS" , 15310, Athens, Greece
| | - Jose Marquez-Velasco
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS" , 15310, Athens, Greece
- National Technical University of Athens , Department of Physics, 15780 Athens, Greece
| | - Sigiava Aminalragia Giamini
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS" , 15310, Athens, Greece
- University of Athens , Department of Physics, Section of Solid State Physics, 15684 Athens, Greece
| | - Nicolaos Kelaidis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS" , 15310, Athens, Greece
| | - Vassilis Psycharis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS" , 15310, Athens, Greece
| | - Athanasios Dimoulas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS" , 15310, Athens, Greece
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d'Acapito F, Torrengo S, Xenogiannopoulou E, Tsipas P, Marquez Velasco J, Tsoutsou D, Dimoulas A. Evidence for Germanene growth on epitaxial hexagonal (h)-AlN on Ag(1 1 1). J Phys Condens Matter 2016; 28:045002. [PMID: 26751008 DOI: 10.1088/0953-8984/28/4/045002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In this work, a structural analysis of Ge layers deposited by molecular beam epitaxy (MBE) on Ag(1 1 1) surfaces with and without an AlN buffer layer have been investigated by x-ray Absorption Spectroscopy (XAS) at the Ge-K edge. For the Ge layers deposited on h-AlN buffer layer on Ag(1 1 1) an interatomic Ge-Ge distance [Formula: see text] Å is found, typical of 2-Dimensional Ge layers and in agreement with the theoretical predictions for free standing low-buckled Germanene presented in literature. First principles calculations, performed in the density functional theory (DFT) framework, supported the experimental RHEED and XAS findings, providing evidence for the epitaxial 2-D Ge layer formation on h-AlN/Ag(1 1 1) template.
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Affiliation(s)
- F d'Acapito
- CNR-IOM-OGG c/o European Synchrotron Radiation Facility, 71 Avenue des Martyrs, F-38043 Grenoble, France
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20
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Tsoutsou D, Aretouli KE, Tsipas P, Marquez-Velasco J, Xenogiannopoulou E, Kelaidis N, Aminalragia Giamini S, Dimoulas A. Epitaxial 2D MoSe2 (HfSe2) Semiconductor/2D TaSe2 Metal van der Waals Heterostructures. ACS Appl Mater Interfaces 2016; 8:1836-41. [PMID: 26727305 DOI: 10.1021/acsami.5b09743] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Molecular beam epitaxy of 2D metal TaSe2/2D MoSe2 (HfSe2) semiconductor heterostructures on epi-AlN(0001)/Si(111) substrates is reported. Electron diffraction reveals an in-plane orientation indicative of van der Waals epitaxy, whereas electronic band imaging supported by first-principles calculations and X-ray photoelectron spectroscopy indicate the presence of a dominant trigonal prismatic 2H-TaSe2 phase and a minor contribution from octahedrally coordinated TaSe2, which is present in TaSe2/AlN and TaSe2/HfSe2/AlN but notably absent in the TaSe2/MoSe2/AlN, indicating superior structural quality of TaSe2 grown on MoSe2. Apart from its structural and chemical compatibility with the selenide semiconductors, TaSe2 has a workfunction of 5.5 eV as measured by ultraviolet photoelectron spectroscopy, which matches very well with the semiconductor workfunctions, implying that epi-TaSe2 can be used for low-resistivity contacts to MoSe2 and HfSe2.
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Affiliation(s)
- Dimitra Tsoutsou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", 15310 Athens, Greece
| | - Kleopatra E Aretouli
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", 15310 Athens, Greece
- University of Athens , Department of Physics, Section of Solid State Physics, 15684 Athens, Greece
| | - Polychronis Tsipas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", 15310 Athens, Greece
| | - Jose Marquez-Velasco
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", 15310 Athens, Greece
- National Technical University of Athens , Department of Physics, 15780 Athens, Greece
| | - Evangelia Xenogiannopoulou
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", 15310 Athens, Greece
| | - Nikolaos Kelaidis
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", 15310 Athens, Greece
| | - Sigiava Aminalragia Giamini
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", 15310 Athens, Greece
- University of Athens , Department of Physics, Section of Solid State Physics, 15684 Athens, Greece
| | - Athanasios Dimoulas
- Institute of Nanoscience and Nanotechnology, National Center for Scientific Research "DEMOKRITOS", 15310 Athens, Greece
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21
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Garas G, Poulasouchidou M, Dimoulas A, Hytiroglou P, Kita M, Zacharakis E. Radiological considerations and surgical planning in the treatment of giant parathyroid adenomas. Ann R Coll Surg Engl 2015; 97:e64-6. [PMID: 26263956 DOI: 10.1308/003588415x14181254789682] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Giant parathyroid adenomas constitute a rare clinical entity, particularly in the developed world. We report the case of a 53-year-old woman where the initial ultrasonography significantly underestimated the size of the lesion. The subsequent size and weight of the adenoma (7 cm diameter, 27 g) combined with the severity of the hypercalcaemia raised the suspicion for the presence of a parathyroid carcinoma. This was later disproven by the surgical and histological findings. Giant parathyroid adenomas are encountered infrequently among patients with primary hyperparathyroidism, and appear to have distinct clinical and biochemical features related to specific genomic alterations. Cross-sectional imaging is mandated in the investigation of parathyroid adenomas presenting with severe hypercalcaemia as ultrasonography alone can underestimate their size and extent. This is important since it can impact on preoperative preparation and planning as well as the consent process as a thoracic approach may prove necessary for certain cases.
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Affiliation(s)
- G Garas
- St. Mary's Hospital, Imperial College London , UK
| | | | - A Dimoulas
- St Luke's Hospital, Thessaloniki , Greece
| | | | - M Kita
- Hippokration Hospital, Thessaloniki , Greece
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22
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Velasco JM, Giamini SA, Kelaidis N, Tsipas P, Tsoutsou D, Kordas G, Raptis YS, Boukos N, Dimoulas A. Reducing the layer number of AB stacked multilayer graphene grown on nickel by annealing at low temperature. Nanotechnology 2015; 26:405603. [PMID: 26377604 DOI: 10.1088/0957-4484/26/40/405603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Controlling the number of layers of graphene grown by chemical vapor deposition is crucial for large scale graphene application. We propose here an etching process of graphene which can be applied immediately after growth to control the number of layers. We use nickel (Ni) foil at high temperature (T = 900 °C) to produce multilayer-AB-stacked-graphene (MLG). The etching process is based on annealing the samples in a hydrogen/argon atmosphere at a relatively low temperature (T = 450 °C) inside the growth chamber. The extent of etching is mainly controlled by the annealing process duration. Using Raman spectroscopy we demonstrate that the number of layers was reduced, changing from MLG to few-layer-AB-stacked-graphene and in some cases to randomly oriented few layer graphene near the substrate. Furthermore, our method offers the significant advantage that it does not introduce defects in the samples, maintaining their original high quality. This fact and the low temperature our method uses make it a good candidate for controlling the layer number of already grown graphene in processes with a low thermal budget.
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Affiliation(s)
- J Marquez Velasco
- National Center for Scientific Research 'Demokritos', 15310 Athens, Greece. Department of Physics, National Technical University of Athens, Athens, Greece
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Abstract
Silicene is the silicon counterpart of graphene, i.e. it consists in a single layer of Si atoms with a hexagonal arrangement. We present a review of recent theoretical and experimental works on this novel two dimensional material. We discuss first the structural, electronic and vibrational properties of free-standing silicene, as predicted from first-principles calculations. We next review theoretical studies on the interaction of silicene with different substrates. The growth and experimental characterization of silicene on Ag(1 1 1) is next discussed, providing insights into the different phases or atomic arrangements of silicene observed on this metallic surface, as well as on its electronic structure. Recent experimental findings about the likely formation of hexagonal Si nanosheets on MoS2 are also highlighted.
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Affiliation(s)
- M Houssa
- Department of Physics and Astronomy, University of Leuven, B-3001 Leuven, Belgium
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Xenogiannopoulou E, Tsipas P, Aretouli KE, Tsoutsou D, Giamini SA, Bazioti C, Dimitrakopulos GP, Komninou P, Brems S, Huyghebaert C, Radu IP, Dimoulas A. High-quality, large-area MoSe2 and MoSe2/Bi2Se3 heterostructures on AlN(0001)/Si(111) substrates by molecular beam epitaxy. Nanoscale 2015; 7:7896-905. [PMID: 25856730 DOI: 10.1039/c4nr06874b] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Atomically-thin, inherently 2D semiconductors offer thickness scaling of nanoelectronic devices and excellent response to light for low-power versatile applications. Using small exfoliated flakes, advanced devices and integrated circuits have already been realized, showing great potential to impact nanoelectronics. Here, high-quality single-crystal MoSe2 is grown by molecular beam epitaxy on AlN(0001)/Si(111), showing the potential for scaling up growth to low-cost, large-area substrates for mass production. The MoSe2 layers are epitaxially aligned with the aluminum nitride (AlN) lattice, showing a uniform, smooth surface and interfaces with no reaction or intermixing, and with sufficiently high band offsets. High-quality single-layer MoSe2 is obtained, with a direct gap evidenced by angle-resolved photoemission spectroscopy and further confirmed by Raman and intense room temperature photoluminescence. The successful growth of high-quality MoSe2/Bi2Se3 multilayers on AlN shows promise for novel devices exploiting the non-trivial topological properties of Bi2Se3.
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Affiliation(s)
- E Xenogiannopoulou
- Institute of Nanoscience and Nanotechnology, NCSR DEMOKRITOS, GR-15310, Athens, Greece.
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Tsipas P, Xenogiannopoulou E, Kassavetis S, Tsoutsou D, Golias E, Bazioti C, Dimitrakopulos GP, Komninou P, Liang H, Caymax M, Dimoulas A. Observation of surface Dirac cone in high-quality ultrathin epitaxial Bi2Se3 topological insulator on AlN(0001) dielectric. ACS Nano 2014; 8:6614-6619. [PMID: 24915126 DOI: 10.1021/nn502397x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Bi2Se3 topological insulators (TIs) are grown on AlN(0001)/Si(111) substrates by molecular beam epitaxy. In a one-step growth at optimum temperature of 300 °C, Bi2Se3 bonds strongly with AlN without forming interfacial reaction layers. This produces high epitaxial quality Bi2Se3 single crystals with a perfect registry with the substrate and abrupt interfaces, allowing thickness scaling down to three quintuple layers (QL) without jeopardizing film quality. It is found by angle-resolved photoelectron spectroscopy that, remarkably, Bi2Se3 films maintain the 3D TI properties at very low thickness of 3QL (∼2.88 nm), exhibiting top surface gapless metallic states in the form of a Dirac cone.
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Affiliation(s)
- Polychronis Tsipas
- National Center for Scientific Research, DEMOKRITOS , 15310 Athens, Greece
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26
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Kaltsas D, Tsetseris L, Dimoulas A. Structural evolution of single-layer films during deposition of silicon on silver: a first-principles study. J Phys Condens Matter 2012; 24:442001. [PMID: 22976803 DOI: 10.1088/0953-8984/24/44/442001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In the quest for the construction of silicene, the silicon analogue of graphene, recent experimental studies have identified a number of distinct ultrathin Si over-layer structures on a Ag(111) surface. Here we use first-principles calculations to probe associated atomic-scale mechanisms that can give rise to this rich behavior of Si wetting layers. We find that the interaction between the Si film and the Ag substrate, neither too strong nor too weak, combined with the possibility of buckling, allows for the incorporation of a number of excess Si adatoms in continuous overlayers with a honeycomb network topology. Depending on the Si coverage, we thus obtain a hierarchy of Si mono-atomic films, in agreement with experiments.
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Affiliation(s)
- D Kaltsas
- Department of Physics, National Technical University of Athens, Athens, Greece.
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Tahini H, Chroneos A, Grimes RW, Schwingenschlögl U, Dimoulas A. Strain-induced changes to the electronic structure of germanium. J Phys Condens Matter 2012; 24:195802. [PMID: 22510461 DOI: 10.1088/0953-8984/24/19/195802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Density functional theory calculations (DFT) are used to investigate the strain-induced changes to the electronic structure of biaxially strained (parallel to the (001), (110) and (111) planes) and uniaxially strained (along the [001], [110] and [111] directions) germanium (Ge). It is calculated that a moderate uniaxial strain parallel to the [111] direction can efficiently transform Ge to a direct bandgap material with a bandgap energy useful for technological applications.
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Affiliation(s)
- H Tahini
- Department of Materials, Imperial College London, London, UK.
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Dimoulas A, Heida J, vWees B, Klapwijk T, vdGraaf W, Borghs G. Phase-Dependent Resistance in a Superconductor-Two-Dimensional-Electron-Gas Quasiparticle Interferometer. Phys Rev Lett 1995; 74:602-605. [PMID: 10058799 DOI: 10.1103/physrevlett.74.602] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Dimoulas A, Leng J, Giapis KP, Georgakilas A, Michelakis C, Christou A. Interband transitions in InxGa1-xAs/In0.52Al0.48As single quantum wells studied by room-temperature modulation spectroscopy. Phys Rev B Condens Matter 1993; 47:7198-7207. [PMID: 10004717 DOI: 10.1103/physrevb.47.7198] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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