1
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Frommelius A, Wirth K, Ohlerth T, Siebenkotten D, Wintersteller S, Abouserie A, Du H, Mayer J, Yarema M, Taubner T, Simon U. 3D Confinement Stabilizes the Metastable Amorphous State of Antimony Nanoparticles - A New Material for Miniaturized Phase Change Memories? SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2402257. [PMID: 38990893 DOI: 10.1002/smll.202402257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 06/30/2024] [Indexed: 07/13/2024]
Abstract
The wet-chemical synthesis of 3D confined antimony nanoparticles (Sb-NP) at low and high temperatures is described. Using reaction conditions that are mild in temperature and strong in reducing power allows the synthesis of amorphous Sb-NP stabilized with organic ligands. Exchanging the organic ligand 1-octanethiol by iodide enabled to investigate the unusual strong stability of this metastable material through simultaneous thermal analysis combining differential scanning calorimetry and thermogravimetric analysis. Additionally, in situ high temperature powder x-ray diffraction (p-XRD) shows a significant increase in stabilization of the amorphous phase in comparison to thin layered, 1D confined Sb or bulk material. Further, it is shown with scattering-type scanning near-field optical microscopy (s-SNOM) experiments that the optical response of the different phases in Sb-NP make the distinctness of each phase possible. It is proposed that the Sb-NP introduced here can serve as a 3D-confined optically addressable nanomaterial of miniaturized phase change memory devices.
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Affiliation(s)
- Anne Frommelius
- Institute for Inorganic Chemistry, RWTH Aachen University, 52074, Aachen, Germany
| | - Konstantin Wirth
- Institute of Experimental Physics, RWTH Aachen University, 52074, Aachen, Germany
| | - Thorsten Ohlerth
- Institute for Inorganic Chemistry, RWTH Aachen University, 52074, Aachen, Germany
| | - Dario Siebenkotten
- Institute of Experimental Physics, RWTH Aachen University, 52074, Aachen, Germany
| | | | - Ahed Abouserie
- Institute for Inorganic Chemistry, RWTH Aachen University, 52074, Aachen, Germany
| | - Hongchu Du
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, Central Facility for Electron Microscopy, RWTH Aachen University and JARA - Fundamentals of Future Information Technologies, 52425, Jülich, Germany
| | - Joachim Mayer
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, Central Facility for Electron Microscopy, RWTH Aachen University and JARA - Fundamentals of Future Information Technologies, 52425, Jülich, Germany
| | - Maksym Yarema
- Institute for Electronics, ETH Zürich, Zürich, 8092, Switzerland
| | - Thomas Taubner
- Institute of Experimental Physics, RWTH Aachen University, 52074, Aachen, Germany
| | - Ulrich Simon
- Institute for Inorganic Chemistry, RWTH Aachen University, 52074, Aachen, Germany
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2
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Kumaar D, Can M, Weigand H, Yarema O, Wintersteller S, Grange R, Wood V, Yarema M. Phase-Controlled Synthesis and Phase-Change Properties of Colloidal Cu-Ge-Te Nanoparticles. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2024; 36:6598-6607. [PMID: 39005536 PMCID: PMC11238340 DOI: 10.1021/acs.chemmater.4c01009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 06/07/2024] [Accepted: 06/10/2024] [Indexed: 07/16/2024]
Abstract
Phase-change memory (PCM) technology has recently attracted a vivid interest for neuromorphic applications, in-memory computing, and photonic integration due to the tunable refractive index and electrical conductivity between the amorphous and crystalline material states. Despite this, it is increasingly challenging to scale down the device dimensions of conventionally sputtered PCM memory arrays, restricting the implementation of PCM technology in mass applications such as consumer electronics. Here, we report the synthesis and structural study of sub-10 nm Cu-Ge-Te (CGT) nanoparticles as suitable candidates for low-cost and ultrasmall PCM devices. We show that our synthesis approach can accurately control the structure of the CGT colloids, such as composition-tuned CGT amorphous nanoparticles as well as crystalline CGT nanoparticles with trigonal α-GeTe and tetragonal Cu2GeTe3 phases. In situ characterization techniques such as high-temperature X-ray diffraction and X-ray absorption spectroscopy reveal that Cu doping in GeTe improves the thermal properties and amorphous phase stability of the nanoparticles, in addition to nanoscale effects, which enhance the nonvolatility characteristics of CGT nanoparticles even further. Moreover, we demonstrate the thin-film fabrication of CGT nanoparticles and characterize their optical properties with spectroscopic ellipsometry measurements. We reveal that CGT nanoparticle thin films exhibit a negative reflectivity change and have good reflectivity contrast in the near-IR spectrum. Our work promotes the possibility to use PCM in nanoparticle form for applications such as electro-optical switching devices, metalenses, reflectivity displays, and phase-change IR devices.
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Affiliation(s)
- Dhananjeya Kumaar
- Chemistry and Materials Design, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092 Zürich, Switzerland
| | - Matthias Can
- Chemistry and Materials Design, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092 Zürich, Switzerland
| | - Helena Weigand
- Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Olesya Yarema
- Materials and Device Engineering, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092 Zürich, Switzerland
| | - Simon Wintersteller
- Chemistry and Materials Design, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092 Zürich, Switzerland
| | - Rachel Grange
- Optical Nanomaterial Group, Institute for Quantum Electronics, Department of Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Vanessa Wood
- Materials and Device Engineering, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092 Zürich, Switzerland
| | - Maksym Yarema
- Chemistry and Materials Design, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092 Zürich, Switzerland
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3
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Wintersteller S, Yarema O, Kumaar D, Schenk FM, Safonova OV, Abdala PM, Wood V, Yarema M. Unravelling the amorphous structure and crystallization mechanism of GeTe phase change memory materials. Nat Commun 2024; 15:1011. [PMID: 38307863 PMCID: PMC10837456 DOI: 10.1038/s41467-024-45327-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 01/17/2024] [Indexed: 02/04/2024] Open
Abstract
The reversible phase transitions in phase-change memory devices can switch on the order of nanoseconds, suggesting a close structural resemblance between the amorphous and crystalline phases. Despite this, the link between crystalline and amorphous tellurides is not fully understood nor quantified. Here we use in-situ high-temperature x-ray absorption spectroscopy (XAS) and theoretical calculations to quantify the amorphous structure of bulk and nanoscale GeTe. Based on XAS experiments, we develop a theoretical model of the amorphous GeTe structure, consisting of a disordered fcc-type Te sublattice and randomly arranged chains of Ge atoms in a tetrahedral coordination. Strikingly, our intuitive and scalable model provides an accurate description of the structural dynamics in phase-change memory materials, observed experimentally. Specifically, we present a detailed crystallization mechanism through the formation of an intermediate, partially stable 'ideal glass' state and demonstrate differences between bulk and nanoscale GeTe leading to size-dependent crystallization temperature.
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Affiliation(s)
- Simon Wintersteller
- Chemistry and Materials Design, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092, Zürich, Switzerland
| | - Olesya Yarema
- Materials and Device Engineering, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092, Zürich, Switzerland
| | - Dhananjeya Kumaar
- Chemistry and Materials Design, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092, Zürich, Switzerland
| | - Florian M Schenk
- Chemistry and Materials Design, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092, Zürich, Switzerland
| | | | - Paula M Abdala
- Laboratory of Energy Science and Engineering, Department of Mechanical and Process Engineering, ETH Zurich, 8092, Zürich, Switzerland
| | - Vanessa Wood
- Materials and Device Engineering, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092, Zürich, Switzerland
| | - Maksym Yarema
- Chemistry and Materials Design, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zürich, 8092, Zürich, Switzerland.
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4
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Schenk FM, Zellweger T, Kumaar D, Bošković D, Wintersteller S, Solokha P, De Negri S, Emboras A, Wood V, Yarema M. Phase-Change Memory from Molecular Tellurides. ACS NANO 2024; 18:1063-1072. [PMID: 38117038 PMCID: PMC10786157 DOI: 10.1021/acsnano.3c10312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 12/21/2023]
Abstract
Phase-change memory (PCM) is an emerging memory technology based on the resistance contrast between the crystalline and amorphous states of a material. Further development and realization of PCM as a mainstream memory technology rely on innovative materials and inexpensive fabrication methods. Here, we propose a generalizable and scalable solution-processing approach to synthesize phase-change telluride inks in order to meet demands for high-throughput material screening, increased energy efficiency, and advanced device architectures. Bulk tellurides, such as Sb2Te3, GeTe, Sc2Te3, and TiTe2, are dissolved and purified to obtain inks of molecular metal telluride complexes. This allowed us to unlock a wide range of solution-processed ternary tellurides by the simple mixing of binary inks. We demonstrate accurate and quantitative composition control, including prototype materials (Ge-Sb-Te) and emerging rare-earth-metal telluride-doped materials (Sc-Sb-Te). Spin-coating and annealing convert ink formulations into high-quality, phase-pure telluride films with preferred orientation along the (00l) direction. Deposition engineering of liquid tellurides enables thickness-tunable films, infilling of nanoscale vias, and film preparation on flexible substrates. Finally, we demonstrate cyclable and non-volatile prototype memory devices, achieving performance indicators such as resistance contrast and low reset energy on par with state-of-the-art sputtered PCM layers.
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Affiliation(s)
- Florian M Schenk
- Chemistry and Materials Design Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Till Zellweger
- Integrated Systems Laboratory, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Dhananjeya Kumaar
- Chemistry and Materials Design Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Darijan Bošković
- Chemistry and Materials Design Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Simon Wintersteller
- Chemistry and Materials Design Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Pavlo Solokha
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, I-16146 Genova, Italy
| | - Serena De Negri
- Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, I-16146 Genova, Italy
| | - Alexandros Emboras
- Integrated Systems Laboratory, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Vanessa Wood
- Materials and Device Engineering Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
| | - Maksym Yarema
- Chemistry and Materials Design Group, Institute for Electronics, Department of Information Technology and Electrical Engineering, ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland
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5
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Tripathi D, Vyas HS, Kumar S, Panda SS, Hegde R. Recent developments in Chalcogenide phase change material-based nanophotonics. NANOTECHNOLOGY 2023; 34:502001. [PMID: 37595569 DOI: 10.1088/1361-6528/acf1a7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 08/18/2023] [Indexed: 08/20/2023]
Abstract
There is now a deep interest in actively reconfigurable nanophotonics as they will enable the next generation of optical devices. Of the various alternatives being explored for reconfigurable nanophotonics, Chalcogenide phase change materials (PCMs) are considered highly promising owing to the nonvolatile nature of their phase change. Chalcogenide PCM nanophotonics can be broadly classified into integrated photonics (with guided wave light propagation) and Meta-optics (with free space light propagation). Despite some early comprehensive reviews, the pace of development in the last few years has shown the need for a topical review. Our comprehensive review covers recent progress on nanophotonic architectures, tuning mechanisms, and functionalities in tunable PCM Chalcogenides. In terms of integrated photonics, we identify novel PCM nanoantenna geometries, novel material utilization, the use of nanostructured waveguides, and sophisticated excitation pulsing schemes. On the meta-optics front, the breadth of functionalities has expanded, enabled by exploring design aspects for better performance. The review identifies immediate, and intermediate-term challenges and opportunities in (1) the development of novel chalcogenide PCM, (2) advance in tuning mechanism, and (3) formal inverse design methods, including machine learning augmented inverse design, and provides perspectives on these aspects. The topical review will interest researchers in further advancing this rapidly growing subfield of nanophotonics.
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Affiliation(s)
- Devdutt Tripathi
- Department of Electrical Engineering, IIT Gandhinagar, 382355, India
| | | | - Sushil Kumar
- Department of Electrical Engineering, IIT Gandhinagar, 382355, India
| | | | - Ravi Hegde
- Department of Electrical Engineering, IIT Gandhinagar, 382355, India
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6
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Kumaar D, Can M, Portner K, Weigand H, Yarema O, Wintersteller S, Schenk F, Boskovic D, Pharizat N, Meinert R, Gilshtein E, Romanyuk Y, Karvounis A, Grange R, Emboras A, Wood V, Yarema M. Colloidal Ternary Telluride Quantum Dots for Tunable Phase Change Optics in the Visible and Near-Infrared. ACS NANO 2023; 17:6985-6997. [PMID: 36971128 PMCID: PMC10100560 DOI: 10.1021/acsnano.3c01187] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 03/23/2023] [Indexed: 06/18/2023]
Abstract
A structural change between amorphous and crystalline phase provides a basis for reliable and modular photonic and electronic devices, such as nonvolatile memory, beam steerers, solid-state reflective displays, or mid-IR antennas. In this paper, we leverage the benefits of liquid-based synthesis to access phase-change memory tellurides in the form of colloidally stable quantum dots. We report a library of ternary MxGe1-xTe colloids (where M is Sn, Bi, Pb, In, Co, Ag) and then showcase the phase, composition, and size tunability for Sn-Ge-Te quantum dots. Full chemical control of Sn-Ge-Te quantum dots permits a systematic study of structural and optical properties of this phase-change nanomaterial. Specifically, we report composition-dependent crystallization temperature for Sn-Ge-Te quantum dots, which is notably higher compared to bulk thin films. This gives the synergistic benefit of tailoring dopant and material dimension to combine the superior aging properties and ultrafast crystallization kinetics of bulk Sn-Ge-Te, while improving memory data retention due to nanoscale size effects. Furthermore, we discover a large reflectivity contrast between amorphous and crystalline Sn-Ge-Te thin films, exceeding 0.7 in the near-IR spectrum region. We utilize these excellent phase-change optical properties of Sn-Ge-Te quantum dots along with liquid-based processability for nonvolatile multicolor images and electro-optical phase-change devices. Our colloidal approach for phase-change applications offers higher customizability of materials, simpler fabrication, and further miniaturization to the sub-10 nm phase-change devices.
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Affiliation(s)
- Dhananjeya Kumaar
- Chemistry
and Materials Design, Institute for Electronics, Department of Information
Technology and Electrical Engineering, ETH
Zürich, 8092 Zürich, Switzerland
| | - Matthias Can
- Chemistry
and Materials Design, Institute for Electronics, Department of Information
Technology and Electrical Engineering, ETH
Zürich, 8092 Zürich, Switzerland
| | - Kevin Portner
- Integrated
Systems Laboratory, Department of Information Technology and Electrical
Engineering, ETH Zürich, 8092 Zürich, Switzerland
| | - Helena Weigand
- Optical
Nanomaterial Group, Institute for Quantum Electronics, Department
of Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Olesya Yarema
- Materials
and Device Engineering, Institute for Electronics, Department of Information
Technology and Electrical Engineering, ETH
Zürich, 8092 Zürich, Switzerland
| | - Simon Wintersteller
- Chemistry
and Materials Design, Institute for Electronics, Department of Information
Technology and Electrical Engineering, ETH
Zürich, 8092 Zürich, Switzerland
| | - Florian Schenk
- Chemistry
and Materials Design, Institute for Electronics, Department of Information
Technology and Electrical Engineering, ETH
Zürich, 8092 Zürich, Switzerland
| | - Darijan Boskovic
- Chemistry
and Materials Design, Institute for Electronics, Department of Information
Technology and Electrical Engineering, ETH
Zürich, 8092 Zürich, Switzerland
| | - Nathan Pharizat
- Chemistry
and Materials Design, Institute for Electronics, Department of Information
Technology and Electrical Engineering, ETH
Zürich, 8092 Zürich, Switzerland
| | - Robin Meinert
- Integrated
Systems Laboratory, Department of Information Technology and Electrical
Engineering, ETH Zürich, 8092 Zürich, Switzerland
| | - Evgeniia Gilshtein
- Laboratory
for Thin Films and Photovoltaics, Empa −
Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Yaroslav Romanyuk
- Laboratory
for Thin Films and Photovoltaics, Empa −
Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Artemios Karvounis
- Optical
Nanomaterial Group, Institute for Quantum Electronics, Department
of Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Rachel Grange
- Optical
Nanomaterial Group, Institute for Quantum Electronics, Department
of Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Alexandros Emboras
- Integrated
Systems Laboratory, Department of Information Technology and Electrical
Engineering, ETH Zürich, 8092 Zürich, Switzerland
| | - Vanessa Wood
- Materials
and Device Engineering, Institute for Electronics, Department of Information
Technology and Electrical Engineering, ETH
Zürich, 8092 Zürich, Switzerland
| | - Maksym Yarema
- Chemistry
and Materials Design, Institute for Electronics, Department of Information
Technology and Electrical Engineering, ETH
Zürich, 8092 Zürich, Switzerland
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7
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Wang W, Zhang M, Pan Z, Biesold GM, Liang S, Rao H, Lin Z, Zhong X. Colloidal Inorganic Ligand-Capped Nanocrystals: Fundamentals, Status, and Insights into Advanced Functional Nanodevices. Chem Rev 2021; 122:4091-4162. [PMID: 34968050 DOI: 10.1021/acs.chemrev.1c00478] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Colloidal nanocrystals (NCs) are intriguing building blocks for assembling various functional thin films and devices. The electronic, optoelectronic, and thermoelectric applications of solution-processed, inorganic ligand (IL)-capped colloidal NCs are especially promising as the performance of related devices can substantially outperform their organic ligand-capped counterparts. This in turn highlights the significance of preparing IL-capped NC dispersions. The replacement of initial bulky and insulating ligands capped on NCs with short and conductive inorganic ones is a critical step in solution-phase ligand exchange for preparing IL-capped NCs. Solution-phase ligand exchange is extremely appealing due to the highly concentrated NC inks with completed ligand exchange and homogeneous ligand coverage on the NC surface. In this review, the state-of-the-art of IL-capped NCs derived from solution-phase inorganic ligand exchange (SPILE) reactions are comprehensively reviewed. First, a general overview of the development and recent advancements of the synthesis of IL-capped colloidal NCs, mechanisms of SPILE, elementary reaction principles, surface chemistry, and advanced characterizations is provided. Second, a series of important factors in the SPILE process are offered, followed by an illustration of how properties of NC dispersions evolve after ILE. Third, surface modifications of perovskite NCs with use of inorganic reagents are overviewed. They are necessary because perovskite NCs cannot withstand polar solvents or undergo SPILE due to their soft ionic nature. Fourth, an overview of the research progresses in utilizing IL-capped NCs for a wide range of applications is presented, including NC synthesis, NC solid and film fabrication techniques, field effect transistors, photodetectors, photovoltaic devices, thermoelectric, and photoelectrocatalytic materials. Finally, the review concludes by outlining the remaining challenges in this field and proposing promising directions to further promote the development of IL-capped NCs in practical application in the future.
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Affiliation(s)
- Wenran Wang
- Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, 483 Wushan Road, Guangzhou 510642, China.,School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
| | - Meng Zhang
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Zhenxiao Pan
- Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, 483 Wushan Road, Guangzhou 510642, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
| | - Gill M Biesold
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Shuang Liang
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Huashang Rao
- Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, 483 Wushan Road, Guangzhou 510642, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
| | - Zhiqun Lin
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Xinhua Zhong
- Key Laboratory for Biobased Materials and Energy of Ministry of Education, College of Materials and Energy, South China Agricultural University, 483 Wushan Road, Guangzhou 510642, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
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8
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Kauzlarich SM, Ju Z, Tseng E, Lundervold J. Recent developments in germanium containing clusters in intermetallics and nanocrystals. Chem Soc Rev 2021; 50:13236-13252. [PMID: 34726681 DOI: 10.1039/d1cs00538c] [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
Multimetallic clusters can be described as building blocks in intermetallics, compounds prepared from all metals and/or semi-metals, and in Zintl phases, a subset of intermetallics containing metals with large differences in electronegativity. In many cases, these intermetallic and Zintl phases provide the first clue for the possibilities of bond formation between metals and semi-metals. Recent advances in multimetallic clusters found in Zintl phases and nanoparticles focusing on Ge with transition metals and semi-metals is presented. Colloidal routes to Ge nanocrystals provide an opportunity for kinetically stabilized Ge-metal and Ge-semi-metal bonding. These routes provide crystalline nanoclusters of Ge, hereafter referred to as nanocrystals, that can be structurally characterized. Compositions of Ge nanocrystals containing transition metals, and the semi-metals, Sb, Bi, and Sn, whose structures have recently been elucidated through EXAFS, will be presented along with potential applications.
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Affiliation(s)
- Susan M Kauzlarich
- Chemistry Department, One Shields Ave, University of California, Davis, CA 95616, USA.
| | - Zheng Ju
- Chemistry Department, One Shields Ave, University of California, Davis, CA 95616, USA.
| | - Emily Tseng
- Chemistry Department, One Shields Ave, University of California, Davis, CA 95616, USA.
| | - Jesse Lundervold
- Chemistry Department, One Shields Ave, University of California, Davis, CA 95616, USA.
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9
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Choi YJ, Jhi SH. Efficient Training of Machine Learning Potentials by a Randomized Atomic-System Generator. J Phys Chem B 2020; 124:8704-8710. [PMID: 32910653 DOI: 10.1021/acs.jpcb.0c05075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Machine learning potentials provide an efficient and comprehensive tool to simulate large-scale systems inaccessible by conventional first-principles methods still in a similar level of accuracy. One critical issue in constructing machine learning potentials is to build training data sets cost-effectively that can represent the potential energy surface in a wide range of configurations. We develop a scheme named randomized atomic-system generator (RAG) to produce the training sets that widely cover the potential energy surface by combining the random sampling and structural optimization. We apply the scheme to construct the machine learning potentials for simulation of chalcogen-based phase change materials. Constructed machine learning potentials successfully simulate the dynamics of melting and crystallization processes of binary GeTe at a level comparable to first-principles simulations. The visual analysis shows that the RAG-generated training set represents the crystallization process including the amorphous phases. From the velocity autocorrelation function obtained from the molecular dynamics simulations, we calculate the phonon density of states to analyze the vibrational properties during crystallization.
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Affiliation(s)
- Young-Jae Choi
- Department of Physics, POSTECH, Cheongam-ro 77, Pohang 37673, Republic of Korea
| | - Seung-Hoon Jhi
- Department of Physics, POSTECH, Cheongam-ro 77, Pohang 37673, Republic of Korea
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10
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Kooi BJ, Wuttig M. Chalcogenides by Design: Functionality through Metavalent Bonding and Confinement. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1908302. [PMID: 32243014 DOI: 10.1002/adma.201908302] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/03/2020] [Accepted: 02/03/2020] [Indexed: 05/27/2023]
Abstract
A unified picture of different application areas for incipient metals is presented. This unconventional material class includes several main-group chalcogenides, such as GeTe, PbTe, Sb2 Te3 , Bi2 Se3 , AgSbTe2 and Ge2 Sb2 Te5 . These compounds and related materials show a unique portfolio of physical properties. A novel map is discussed, which helps to explain these properties and separates the different fundamental bonding mechanisms (e.g., ionic, metallic, and covalent). The map also provides evidence for an unconventional, new bonding mechanism, coined metavalent bonding (MVB). Incipient metals, employing this bonding mechanism, also show a special bond breaking mechanism. MVB differs considerably from resonant bonding encountered in benzene or graphite. The concept of MVB is employed to explain the unique properties of materials utilizing it. Then, the link is made from fundamental insights to application-relevant properties, crucial for the use of these materials as thermoelectrics, phase change materials, topological insulators or as active photonic components. The close relationship of the materials' properties and their application potential provides optimization schemes for different applications. Finally, evidence will be presented that for metavalently bonded materials interesting effects arise in reduced dimensions. In particular, the consequences for the crystallization kinetics of thin films and nanoparticles will be discussed in detail.
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Affiliation(s)
- Bart J Kooi
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen, 9747 AG, the Netherlands
| | - Matthias Wuttig
- Institute of Physics IA, RWTH Aachen University, Aachen, 52074, Germany
- JARA-Institute: Energy-Efficient Information Technology (Green IT), Forschungszentrum Jülich GmbH, Jülich, 52428, Germany
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