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Zheng M, Liu P, Yan P, Zhou T, Lin X, Li X, Wen L, Xu Q. Heterogeneous CNF/MoO 3 nanofluidic membranes with tunable surface plasmon resonances for solar-osmotic energy conversion. MATERIALS HORIZONS 2024; 11:3375-3385. [PMID: 38686603 DOI: 10.1039/d4mh00286e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Two-dimensional (2D) nanofluidic membranes are competitive candidates for osmotic energy harvesting and have been greatly developed. However, the use of diverse inherent characteristics of 2D nanosheets, such as electronic or optoelectronic properties, to achieve intelligent ion transport, still lacks sufficient exploration. Here, a cellulose nanofiber/molybdenum oxide (CNF/MoO3) heterogeneous nanofluidic membrane with high performance solar-osmotic energy conversion is reported, and how surface plasmon resonances (SPR) regulate selective cation transport is revealed. The SPR of amorphous MoO3 endows the heterogeneous nanofluidic membranes with tunable surface charge and good photothermal conversion. Through DFT calculations and finite element modeling, the regulation of electronic and optoelectronic properties on the surface of materials by SPR and the influence of surface charge density and temperature gradient on ion transport in nanofluidic membranes are demonstrated. By mixing 0.01/0.5 M NaCl solutions using SPR and photothermal effects, the power density can achieve a remarkable value of ≈13.24 W m-2, outperforming state-of-the-art 2D-based nanofluidic membranes. This work first reveals the regulation and mechanism of SPR on ion transport in nanofluidic membranes and systematically studies photon-electron-ion interactions in nanofluidic membranes, which could also provide a new viewpoint for promoting osmotic energy conversion.
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Affiliation(s)
- Mengmeng Zheng
- Henan Institute of Advanced Technology, Zhengzhou University, Zhengzhou 450052, P. R. China.
| | - Pei Liu
- Henan Institute of Advanced Technology, Zhengzhou University, Zhengzhou 450052, P. R. China.
- College of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450052, P. R. China
| | - Pengfei Yan
- Henan Institute of Advanced Technology, Zhengzhou University, Zhengzhou 450052, P. R. China.
| | - Teng Zhou
- College of Mechanical and Electrical Engineering, Hainan University, Haikou, 570228, Hainan, P. R. China
| | - Xiangbin Lin
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
| | - Xin Li
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
| | - Liping Wen
- CAS Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
| | - Qun Xu
- Henan Institute of Advanced Technology, Zhengzhou University, Zhengzhou 450052, P. R. China.
- College of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450052, P. R. China
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2
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Modi G, Meng AC, Rajagopalan S, Thiruvengadam R, Davies PK, Stach EA, Agarwal R. Controlled Self-Assembly of Nanoscale Superstructures in Phase-Change Ge-Sb-Te Nanowires. NANO LETTERS 2024; 24:5799-5807. [PMID: 38701332 DOI: 10.1021/acs.nanolett.4c00878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
Controlled growth of semiconductor nanowires with atomic precision offers the potential to tune the material properties for integration into scalable functional devices. Despite significant progress in understanding the nanowire growth mechanism, definitive control over atomic positions of its constituents, structure, and morphology via self-assembly remains challenging. Here, we demonstrate an exquisite control over synthesis of cation-ordered nanoscale superstructures in Ge-Sb-Te nanowires with the ability to deterministically vary the nanowire growth direction, crystal facets, and periodicity of cation ordering by tuning the relative precursor flux during synthesis. Furthermore, the role of anisotropy on material properties in cation-ordered nanowire superstructures is illustrated by fabricating phase-change memory (PCM) devices, which show significantly different growth direction dependent amorphization current density. This level of control in synthesizing chemically ordered nanoscale superstructures holds potential to precisely modulate fundamental material properties such as the electronic and thermal transport, which may have implications for PCM, thermoelectrics, and other nanoelectronic devices.
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Affiliation(s)
- Gaurav Modi
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Andrew C Meng
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Srinivasan Rajagopalan
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Rangarajan Thiruvengadam
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Peter K Davies
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Eric A Stach
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Ritesh Agarwal
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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3
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Celis J, Cao W. Systematic DFT Modeling van der Waals Heterostructures from a Complete Configurational Basis Applied to γ-PC/WS 2. J Chem Theory Comput 2024; 20:2377-2389. [PMID: 38446034 DOI: 10.1021/acs.jctc.3c00932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
Periodic boundary conditions in density functional theory (DFT)-based modeling of bilayer van der Waals heterostructures introduce an artificial lock to a metastable configuration. Depending on the initial supercell, geometric optimization may reach local energy minima at a fixed twist-angle in a restricted strain-space. In this work, an algorithm was introduced for generating a complete scope of ways to combine two monolayer unit cells into a common supercell. In its application to γ-PC/WS2, 18,123 bilayer supercells were derived, for which the constituting monolayers possessed isotropic strains, anisotropic strains, or intralayer shear strains. Based on analysis, 45 isotropically strained configurations were carefully chosen for optimization by DFT. Geometric and energetic features and band structures were revealed and compared, following the variations at different strains and twist-angles. As such, this case study brought to resolution the impacts of supercell construction on DFT's outcomes and the merits of in-depth screening of the different options. Repetitions and extensions to the demonstrated approach may be applied to characterize van der Waals heterostructures and derivatives in the future.
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Affiliation(s)
- Joran Celis
- Nano and Molecular Systems Research Unit, Faculty of Science, University of Oulu, FIN-90014 Oulu, Finland
| | - Wei Cao
- Nano and Molecular Systems Research Unit, Faculty of Science, University of Oulu, FIN-90014 Oulu, Finland
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4
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Liqin L, Shahzad K, Rauf A, Tchier F, Aslam A. Metric and fault-tolerant metric dimension for GeSbTe superlattice chemical structure. PLoS One 2023; 18:e0290411. [PMID: 38033165 PMCID: PMC10688907 DOI: 10.1371/journal.pone.0290411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 08/08/2023] [Indexed: 12/02/2023] Open
Abstract
The concept of metric dimension has many applications, including optimizing sensor placement in networks and identifying influential persons in social networks, which aids in effective resource allocation and focused interventions; finding the source of a spread in an arrangement; canonically labeling graphs; and inserting typical information in low-dimensional Euclidean spaces. In a graph G, the set S⊆V(G) of minimum vertices from which all other verticescan be uniquely determined by the distances to the vertices in S is called the resolving set. The cardinality of the resolving set is called the metric dimension. The set S is called fault-tolerant resolving set if S\{v} is still a resolving set of G. The minimum cardinality of such a set S is called fault-tolerant metric dimension of G. GeSbTe super lattice is the latest chemical compound to have electronic material that is capable of non-volatile storing phase change memories with minimum energy usage. In this work, we calculate the resolving set (fault tolerant resolving set) to find the metric dimension(fault-tolerant metric dimension) for the molecular structure of the GeSbTe lattice. The results may be useful in comparing network structure and categorizing the structure of the GeSbTe lattice.
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Affiliation(s)
- Liu Liqin
- College of Big Data and Artificial, Anhui Xinhua University, Hefei, Anhui, China
| | - Khurram Shahzad
- Department of Mathematics, Air University Islamabad, Multan Campus, Multan, Pakistan
| | - Abdul Rauf
- Department of Mathematics, Air University Islamabad, Multan Campus, Multan, Pakistan
| | - Fairouz Tchier
- Mathematics Department, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Adnan Aslam
- Department of Natural Sciences and Humanities, University of Engineering and Technology, Lahore RCET, Pakistan
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5
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Meng L, Vu TV, Criscenti LJ, Ho TA, Qin Y, Fan H. Theoretical and Experimental Advances in High-Pressure Behaviors of Nanoparticles. Chem Rev 2023; 123:10206-10257. [PMID: 37523660 DOI: 10.1021/acs.chemrev.3c00169] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Using compressive mechanical forces, such as pressure, to induce crystallographic phase transitions and mesostructural changes while modulating material properties in nanoparticles (NPs) is a unique way to discover new phase behaviors, create novel nanostructures, and study emerging properties that are difficult to achieve under conventional conditions. In recent decades, NPs of a plethora of chemical compositions, sizes, shapes, surface ligands, and self-assembled mesostructures have been studied under pressure by in-situ scattering and/or spectroscopy techniques. As a result, the fundamental knowledge of pressure-structure-property relationships has been significantly improved, leading to a better understanding of the design guidelines for nanomaterial synthesis. In the present review, we discuss experimental progress in NP high-pressure research conducted primarily over roughly the past four years on semiconductor NPs, metal and metal oxide NPs, and perovskite NPs. We focus on the pressure-induced behaviors of NPs at both the atomic- and mesoscales, inorganic NP property changes upon compression, and the structural and property transitions of perovskite NPs under pressure. We further discuss in depth progress on molecular modeling, including simulations of ligand behavior, phase-change chalcogenides, layered transition metal dichalcogenides, boron nitride, and inorganic and hybrid organic-inorganic perovskites NPs. These models now provide both mechanistic explanations of experimental observations and predictive guidelines for future experimental design. We conclude with a summary and our insights on future directions for exploration of nanomaterial phase transition, coupling, growth, and nanoelectronic and photonic properties.
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Affiliation(s)
- Lingyao Meng
- Department of Chemistry & Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87106, United States
| | - Tuan V Vu
- Geochemistry Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Louise J Criscenti
- Geochemistry Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Tuan A Ho
- Geochemistry Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Yang Qin
- Department of Chemical & Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Mansfield, Connecticut 06269, United States
| | - Hongyou Fan
- Geochemistry Department, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
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6
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Cui W, Lin W, Lu W, Liu C, Gao Z, Ma H, Zhao W, Van Tendeloo G, Zhao W, Zhang Q, Sang X. Direct observation of cation diffusion driven surface reconstruction at van der Waals gaps. Nat Commun 2023; 14:554. [PMID: 36732335 PMCID: PMC9894939 DOI: 10.1038/s41467-023-35972-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 01/11/2023] [Indexed: 02/04/2023] Open
Abstract
Weak interlayer van der Waals (vdW) bonding has significant impact on the surface/interface structure, electronic properties, and transport properties of vdW layered materials. Unraveling the complex atomistic dynamics and structural evolution at vdW surfaces is therefore critical for the design and synthesis of the next-generation vdW layered materials. Here, we show that Ge/Bi cation diffusion along the vdW gap in layered GeBi2Te4 (GBT) can be directly observed using in situ heating scanning transmission electron microscopy (STEM). The cation concentration variation during diffusion was correlated with the local Te6 octahedron distortion based on a quantitative analysis of the atomic column intensity and position in time-elapsed STEM images. The in-plane cation diffusion leads to out-of-plane surface etching through complex structural evolutions involving the formation and propagation of a non-centrosymmetric GeTe2 triple layer surface reconstruction on fresh vdW surfaces, and GBT subsurface reconstruction from a septuple layer to a quintuple layer. Our results provide atomistic insight into the cation diffusion and surface reconstruction in vdW layered materials.
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Affiliation(s)
- Wenjun Cui
- grid.162110.50000 0000 9291 3229State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 China ,grid.162110.50000 0000 9291 3229Nanostructure Research Center, Wuhan University of Technology, Wuhan, 430070 China
| | - Weixiao Lin
- grid.162110.50000 0000 9291 3229State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 China ,grid.162110.50000 0000 9291 3229Nanostructure Research Center, Wuhan University of Technology, Wuhan, 430070 China
| | - Weichao Lu
- grid.162110.50000 0000 9291 3229State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 China ,grid.162110.50000 0000 9291 3229Nanostructure Research Center, Wuhan University of Technology, Wuhan, 430070 China
| | - Chengshan Liu
- grid.162110.50000 0000 9291 3229State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 China
| | - Zhixiao Gao
- grid.497420.c0000 0004 1798 1132School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao, 266580 Shandong China
| | - Hao Ma
- grid.497420.c0000 0004 1798 1132School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao, 266580 Shandong China
| | - Wen Zhao
- grid.497420.c0000 0004 1798 1132School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao, 266580 Shandong China
| | - Gustaaf Van Tendeloo
- grid.162110.50000 0000 9291 3229Nanostructure Research Center, Wuhan University of Technology, Wuhan, 430070 China ,grid.5284.b0000 0001 0790 3681Electron Microscopy for Materials Science (EMAT), University of Antwerp, Antwerp, B-2020 Belgium
| | - Wenyu Zhao
- grid.162110.50000 0000 9291 3229State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 China
| | - Qingjie Zhang
- grid.162110.50000 0000 9291 3229State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 China
| | - Xiahan Sang
- grid.162110.50000 0000 9291 3229State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 China ,grid.162110.50000 0000 9291 3229Nanostructure Research Center, Wuhan University of Technology, Wuhan, 430070 China
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7
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Yoo C, Jeon JW, Yoon S, Cheng Y, Han G, Choi W, Park B, Jeon G, Jeon S, Kim W, Zheng Y, Lee J, Ahn J, Cho S, Clendenning SB, Karpov IV, Lee YK, Choi JH, Hwang CS. Atomic Layer Deposition of Sb 2 Te 3 /GeTe Superlattice Film and Its Melt-Quenching-Free Phase-Transition Mechanism for Phase-Change Memory. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2207143. [PMID: 36271720 DOI: 10.1002/adma.202207143] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Atomic layer deposition (ALD) of Sb2 Te3 /GeTe superlattice (SL) film on planar and vertical sidewall areas containing TiN metal and SiO2 insulator is demonstrated. The peculiar chemical affinity of the ALD precursor to the substrate surface and the 2D nature of the Sb2 Te3 enable the growth of an in situ crystallized SL film with a preferred orientation. The SL film shows a reduced reset current of ≈1/7 of the randomly oriented Ge2 Sb2 Te5 alloy. The reset switching is induced by the transition from the SL to the (111)-oriented face-centered-cubic (FCC) Ge2 Sb2 Te5 alloy and subsequent melt-quenching-free amorphization. The in-plane compressive stress, induced by the SL-to-FCC structural transition, enhances the electromigration of Ge along the [111] direction of FCC structure, which enables such a significant improvement. Set operation switches the amorphous to the (111)-oriented FCC structure.
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Affiliation(s)
- Chanyoung Yoo
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jeong Woo Jeon
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Seungjae Yoon
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Yan Cheng
- Key Laboratory of Polar Materials and Devices, Department of Electronics, East China Normal University, Shanghai, 200241, China
| | - Gyuseung Han
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Wonho Choi
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Byongwoo Park
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Gwangsik Jeon
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sangmin Jeon
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Woohyun Kim
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yonghui Zheng
- Key Laboratory of Polar Materials and Devices, Department of Electronics, East China Normal University, Shanghai, 200241, China
| | - Jongho Lee
- SK Hynix Inc., Icheon, Gyeonggi, 17336, Republic of Korea
| | - Junku Ahn
- SK Hynix Inc., Icheon, Gyeonggi, 17336, Republic of Korea
| | - Sunglae Cho
- SK Hynix Inc., Icheon, Gyeonggi, 17336, Republic of Korea
| | | | - Ilya V Karpov
- Components Research, Intel Corporation, Hillsboro, OR, 97124, USA
| | - Yoon Kyung Lee
- Division of Advanced Materials Engineering, Jeonbuk National University, Jeonju, Jeonbuk, 54896, Republic of Korea
| | - Jung-Hae Choi
- Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Cheol Seong Hwang
- Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea
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8
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Ning J, Wang Y, Teo TY, Huang CC, Zeimpekis I, Morgan K, Teo SL, Hewak DW, Bosman M, Simpson RE. Low Energy Switching of Phase Change Materials Using a 2D Thermal Boundary Layer. ACS APPLIED MATERIALS & INTERFACES 2022; 14:41225-41234. [PMID: 36043468 DOI: 10.1021/acsami.2c12936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The switchable optical and electrical properties of phase change materials (PCMs) are finding new applications beyond data storage in reconfigurable photonic devices. However, high power heat pulses are needed to melt-quench the material from crystalline to amorphous. This is especially true in silicon photonics, where the high thermal conductivity of the waveguide material makes heating the PCM energy inefficient. Here, we improve the energy efficiency of the laser-induced phase transitions by inserting a layer of two-dimensional (2D) material, either MoS2 or WS2, between the silica or silicon substrate and the PCM. The 2D material reduces the required laser power by at least 40% during the amorphization (RESET) process, depending on the substrate. Thermal simulations confirm that both MoS2 and WS2 2D layers act as a thermal barrier, which efficiently confines energy within the PCM layer. Remarkably, the thermal insulation effect of the 2D layer is equivalent to a ∼100 nm layer of SiO2. The high thermal boundary resistance induced by the van der Waals (vdW)-bonded layers limits the thermal diffusion through the layer interface. Hence, 2D materials with stable vdW interfaces can be used to improve the thermal efficiency of PCM-tuned Si photonic devices. Furthermore, our waveguide simulations show that the 2D layer does not affect the propagating mode in the Si waveguide; thus, this simple additional thin film produces a substantial energy efficiency improvement without degrading the optical performance of the waveguide. Our findings pave the way for energy-efficient laser-induced structural phase transitions in PCM-based reconfigurable photonic devices.
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Affiliation(s)
- Jing Ning
- Singapore University of Technology and Design (SUTD), 8 Somapah Road, 487372 Singapore
- Department of Materials Science & Engineering, National University of Singapore, 9 Engineering Drive 1, 117575 Singapore
| | - Yunzheng Wang
- Singapore University of Technology and Design (SUTD), 8 Somapah Road, 487372 Singapore
| | - Ting Yu Teo
- Singapore University of Technology and Design (SUTD), 8 Somapah Road, 487372 Singapore
| | - Chung-Che Huang
- Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Ioannis Zeimpekis
- Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Katrina Morgan
- Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Siew Lang Teo
- Institute of Materials Research and Engineering (IMRE), Agency for Science Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis 138634, Singapore
| | - Daniel W Hewak
- Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Michel Bosman
- Department of Materials Science & Engineering, National University of Singapore, 9 Engineering Drive 1, 117575 Singapore
- Institute of Materials Research and Engineering (IMRE), Agency for Science Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis 138634, Singapore
| | - Robert E Simpson
- Singapore University of Technology and Design (SUTD), 8 Somapah Road, 487372 Singapore
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9
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Zheng C, Simpson RE, Tang K, Ke Y, Nemati A, Zhang Q, Hu G, Lee C, Teng J, Yang JKW, Wu J, Qiu CW. Enabling Active Nanotechnologies by Phase Transition: From Electronics, Photonics to Thermotics. Chem Rev 2022; 122:15450-15500. [PMID: 35894820 DOI: 10.1021/acs.chemrev.2c00171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phase transitions can occur in certain materials such as transition metal oxides (TMOs) and chalcogenides when there is a change in external conditions such as temperature and pressure. Along with phase transitions in these phase change materials (PCMs) come dramatic contrasts in various physical properties, which can be engineered to manipulate electrons, photons, polaritons, and phonons at the nanoscale, offering new opportunities for reconfigurable, active nanodevices. In this review, we particularly discuss phase-transition-enabled active nanotechnologies in nonvolatile electrical memory, tunable metamaterials, and metasurfaces for manipulation of both free-space photons and in-plane polaritons, and multifunctional emissivity control in the infrared (IR) spectrum. The fundamentals of PCMs are first introduced to explain the origins and principles of phase transitions. Thereafter, we discuss multiphysical nanodevices for electronic, photonic, and thermal management, attesting to the broad applications and exciting promises of PCMs. Emerging trends and valuable applications in all-optical neuromorphic devices, thermal data storage, and encryption are outlined in the end.
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Affiliation(s)
- Chunqi Zheng
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore.,NUS Graduate School, National University of Singapore, Singapore 119077, Singapore
| | - Robert E Simpson
- Engineering Product Development, Singapore University of Technology and Design (SUTD), Singapore 487372, Singapore
| | - Kechao Tang
- Key Laboratory of Microelectronic Devices and Circuits (MOE), School of Integrated Circuits, Peking University, Beijing 100871, China
| | - Yujie Ke
- Engineering Product Development, Singapore University of Technology and Design (SUTD), Singapore 487372, Singapore
| | - Arash Nemati
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 138634, Singapore
| | - Qing Zhang
- School of Physics, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Guangwei Hu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Chengkuo Lee
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Jinghua Teng
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 138634, Singapore
| | - Joel K W Yang
- Engineering Product Development, Singapore University of Technology and Design (SUTD), Singapore 487372, Singapore.,Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 138634, Singapore
| | - Junqiao Wu
- Department of Materials Science and Engineering, University of California, Berkeley, and Lawrence Berkeley National Laboratory, California 94720, United States
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
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10
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Liu QM, Wu D, Li ZA, Shi LY, Wang ZX, Zhang SJ, Lin T, Hu TC, Tian HF, Li JQ, Dong T, Wang NL. Photoinduced multistage phase transitions in Ta 2NiSe 5. Nat Commun 2021; 12:2050. [PMID: 33824351 PMCID: PMC8024274 DOI: 10.1038/s41467-021-22345-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 03/10/2021] [Indexed: 02/01/2023] Open
Abstract
Ultrafast control of material physical properties represents a rapidly developing field in condensed matter physics. Yet, accessing the long-lived photoinduced electronic states is still in its early stages, especially with respect to an insulator to metal phase transition. Here, by combining transport measurement with ultrashort photoexcitation and coherent phonon spectroscopy, we report on photoinduced multistage phase transitions in Ta2NiSe5. Upon excitation by weak pulse intensity, the system is triggered to a short-lived state accompanied by a structural change. Further increasing the excitation intensity beyond a threshold, a photoinduced steady new state is achieved where the resistivity drops by more than four orders at temperature 50 K. This new state is thermally stable up to at least 350 K and exhibits a lattice structure different from any of the thermally accessible equilibrium states. Transmission electron microscopy reveals an in-chain Ta atom displacement in the photoinduced new structure phase. We also found that nano-sheet samples with the thickness less than the optical penetration depth are required for attaining a complete transition.
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Affiliation(s)
- Q M Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - D Wu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, China.
| | - Z A Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - L Y Shi
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - Z X Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - S J Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - T Lin
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - T C Hu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - H F Tian
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - J Q Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - T Dong
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - N L Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
- Collaborative Innovation Center of Quantum Matter, Beijing, China.
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11
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Zhang H, Yimam DT, de Graaf S, Momand J, Vermeulen PA, Wei Y, Noheda B, Kooi BJ. Strain Relaxation in "2D/2D and 2D/3D Systems": Highly Textured Mica/Bi 2Te 3, Sb 2Te 3/Bi 2Te 3, and Bi 2Te 3/GeTe Heterostructures. ACS NANO 2021; 15:2869-2879. [PMID: 33476130 PMCID: PMC7905873 DOI: 10.1021/acsnano.0c08842] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Strain engineering as a method to control functional properties has seen in the last decades a surge of interest. Heterostructures comprising 2D-materials and containing van der Waals(-like) gaps were considered unsuitable for strain engineering. However, recent work on heterostructures based on Bi2Te3, Sb2Te3, and GeTe showed the potential of a different type of strain engineering due to long-range mutual straining. Still, a comprehensive understanding of the strain relaxation mechanism in these telluride heterostructures is lacking due to limitations of the earlier analyses performed. Here, we present a detailed study of strain in two-dimensional (2D/2D) and mixed dimensional (2D/3D) systems derived from mica/Bi2Te3, Sb2Te3/Bi2Te3, and Bi2Te3/GeTe heterostructures, respectively. We first clearly show the fast relaxation process in the mica/Bi2Te3 system where the strain was generally transferred and confined up to the second or third van der Waals block and then abruptly relaxed. Then we show, using three independent techniques, that the long-range exponentially decaying strain in GeTe and Sb2Te3 grown on the relaxed Bi2Te3 and Bi2Te3 on relaxed Sb2Te3 as directly observed at the growth surface is still present within these three different top layers a long time after growth. The observed behavior points at immediate strain relaxation by plastic deformation without any later relaxation and rules out an elastic (energy minimization) model as was proposed recently. Our work advances the understanding of strain tuning in textured heterostructures or superlattices governed by anisotropic bonding.
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12
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Sun T, Liu F, Guo J, Han G, Zhang Y. A Phase-Change Mechanism of GST-SL Based Superlattices upon Sb Flipping. MATERIALS 2021; 14:ma14020360. [PMID: 33450936 PMCID: PMC7828381 DOI: 10.3390/ma14020360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/07/2021] [Accepted: 01/09/2021] [Indexed: 11/16/2022]
Abstract
Reversible phase-change behaviors of Ge–Sb–Te based superlattices (GST-SL) were studied by ab initio molecular dynamics (AIMD) simulations based on three models containing Ge/Sb intermixing, namely the Petrov-mix, Ferro-mix, and Kooi-mix models. The flipping behavior of Sb atoms was found in all the three GST-SL models in the melting process. Among them the Kooi-mix model exhibited the best stability, and the analyses of bond length distribution and electron localization function provided a better explanation on the phase transition of GST-SL. Finally, we proposed a fast switching model for GST-SL based on Sb flipping.
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Affiliation(s)
- Teng Sun
- Key Laboratory of Trans-Scale Laser Manufacturing Technology, Beijing University of Technology, Ministry of Education, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China; (T.S.); (J.G.); (G.H.); (Y.Z.)
- Beijing Engineering Research Center of Laser Technology, Beijing University of Technology, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China
- Institute of Laser Engineering, Faculty of Materials and Manufacturing, Beijing University of Technology, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China
| | - Furong Liu
- Key Laboratory of Trans-Scale Laser Manufacturing Technology, Beijing University of Technology, Ministry of Education, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China; (T.S.); (J.G.); (G.H.); (Y.Z.)
- Beijing Engineering Research Center of Laser Technology, Beijing University of Technology, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China
- Institute of Laser Engineering, Faculty of Materials and Manufacturing, Beijing University of Technology, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China
- Correspondence: ; Tel.: +86-010-67396559; Fax: +86-010-67392773
| | - Jicheng Guo
- Key Laboratory of Trans-Scale Laser Manufacturing Technology, Beijing University of Technology, Ministry of Education, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China; (T.S.); (J.G.); (G.H.); (Y.Z.)
- Beijing Engineering Research Center of Laser Technology, Beijing University of Technology, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China
- Institute of Laser Engineering, Faculty of Materials and Manufacturing, Beijing University of Technology, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China
| | - Gang Han
- Key Laboratory of Trans-Scale Laser Manufacturing Technology, Beijing University of Technology, Ministry of Education, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China; (T.S.); (J.G.); (G.H.); (Y.Z.)
- Beijing Engineering Research Center of Laser Technology, Beijing University of Technology, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China
- Institute of Laser Engineering, Faculty of Materials and Manufacturing, Beijing University of Technology, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China
| | - Yongzhi Zhang
- Key Laboratory of Trans-Scale Laser Manufacturing Technology, Beijing University of Technology, Ministry of Education, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China; (T.S.); (J.G.); (G.H.); (Y.Z.)
- Beijing Engineering Research Center of Laser Technology, Beijing University of Technology, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China
- Institute of Laser Engineering, Faculty of Materials and Manufacturing, Beijing University of Technology, 100 Ping Leyuan, Chaoyang District, Beijing 100124, China
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13
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Ribaldone C, Dragoni D, Bernasconi M. A first-principles study of the switching mechanism in GeTe/InSbTe superlattices. NANOSCALE ADVANCES 2020; 2:5209-5218. [PMID: 36132039 PMCID: PMC9418462 DOI: 10.1039/d0na00577k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/11/2020] [Indexed: 06/15/2023]
Abstract
Interfacial Phase Change Memories (iPCMs) based on (GeTe)2/Sb2Te3 superlattices have been proposed as an alternative candidate to conventional PCMs for the realization of memory devices with superior switching properties. The switching mechanism was proposed to involve a crystalline-to-crystalline structural transition associated with a rearrangement of the stacking sequence of the GeTe bilayers. Density functional theory (DFT) calculations showed that such rearrangement could be achieved by means of a two-step process with an activation barrier for the flipping of Ge and Te atoms which is sensitive to the biaxial strain acting on GeTe bilayers. Within this picture, strain-engineering of GeTe bilayers in the GeTe-chalcogenide superlattice can be exploited to further improve the iPCM switching performance. In this work, we study GeTe-InSbTe superlattices with different compositions by means of DFT, aiming at exploiting the large mismatch (3.8%) in the in-plane lattice parameter between GeTe and In3SbTe2 to reduce the activation barrier for the switching with respect to the (GeTe)2-Sb2Te3 superlattice.
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Affiliation(s)
- Chiara Ribaldone
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca Via R. Cozzi 55 I-20125 Milano Italy
| | - Daniele Dragoni
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca Via R. Cozzi 55 I-20125 Milano Italy
| | - Marco Bernasconi
- Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca Via R. Cozzi 55 I-20125 Milano Italy
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14
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Feng J, Lotnyk A, Bryja H, Wang X, Xu M, Lin Q, Cheng X, Xu M, Tong H, Miao X. "Stickier"-Surface Sb 2Te 3 Templates Enable Fast Memory Switching of Phase Change Material GeSb 2Te 4 with Growth-Dominated Crystallization. ACS APPLIED MATERIALS & INTERFACES 2020; 12:33397-33407. [PMID: 32597166 DOI: 10.1021/acsami.0c07973] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ge-Sb-Te (GST)-based phase-change memory (PCM) excels in the switching performance but remains insufficient of the operating speed to replace cache memory (the fastest memory in a computer). In this work, a novel approach using Sb2Te3 templates is proposed to boost the crystallization speed of GST by five times faster. This is because such a GST/Sb2Te3 heterostructure changes the crystallizing mode of GST from the nucleation-dominated to the faster growth-dominated one, as confirmed by high-resolution transmission electron microscopy, which captures the interface-induced epitaxial growth of GST on Sb2Te3 templates in devices. Ab initio molecular dynamic simulations reveal that Sb2Te3 templates can render GST sublayers faster crystallization speed because Sb2Te3's "sticky" surface contains lots of unpaired electrons that may attract Ge atoms with less antibonding interactions. Our work not only proposes a template-assisted PCM with fast speed but also uncovers the hidden mechanism of Sb2Te3's sticky surface, which can be used for future material selection.
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Affiliation(s)
- Jinlong Feng
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Leibniz Institute of Surface Engineering (IOM), Permoserstr. 15, Leipzig 04318, Germany
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Andriy Lotnyk
- Leibniz Institute of Surface Engineering (IOM), Permoserstr. 15, Leipzig 04318, Germany
- Laboratory of Infrared Materials and Devices, The Research Institute of Advanced Technologies, Ningbo University, Ningbo 315211, China
| | - Hagen Bryja
- Leibniz Institute of Surface Engineering (IOM), Permoserstr. 15, Leipzig 04318, Germany
| | - Xiaojie Wang
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Meng Xu
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Qi Lin
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiaomin Cheng
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Ming Xu
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Hao Tong
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiangshui Miao
- Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Advanced Memories, Huazhong University of Science and Technology, Wuhan 430074, China
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15
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Han G, Liu F, Li W, Huang Y, Sun N, Ye F. Local structure and phase change behavior in interfacial intermixing GeTe-Sb 2Te 3 superlattices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:255401. [PMID: 32050167 DOI: 10.1088/1361-648x/ab7577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ge/Sb atomic intermixing in interfacial cationic layers is a common phenomenon for GeTe-Sb2Te3 superlattice (GST-SL) used in memory devices. In this paper, we explored the effect of Ge/Sb intermixing on the phase change behavior of GST-SL upon the heating-quenching procedure. Four interfacial intermixing models of Kooi, Ferro, Petrov and inverted Petrov with different Ge/Sb intermixing ratios (25/75, 50/50 and 75/25) were developed based on the ab initio molecular dynamics. The structural evolution indicated that the Ge/Sb interfacial intermixing could facilitate the structure changes especially for 50/50 Ge/Sb intermixed models. When quenching from 1500 K, more 4-fold Ge-centered octahedrons were produced than tetrahedrons, and the electron localization function further proved that the distorted of Ge(Sb)-centered 6-fold octahedrons were caused by the asymmetrical interactions of Ge-Ge/Sb and Ge-Te. A relatively large Te p orbital contribution in coexisted Ge/Te layer led to a narrower bandgap. In addition, different Ge/Sb atom intermixed ratio which affected the electronic local structure, led to the discrepancy in the initial atom movement of Sb or Ge movement near the gap. The present studies enrich the understanding of Ge/Sb interfacial atomic intermixing effects in GST-SL structural changes.
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Affiliation(s)
- Gang Han
- Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, People's Republic of China. Beijing Engineering Research Center of Applied Laser Technology, Beijing University of Technology, Beijing 100124, People's Republic of China
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16
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Ryu YK, Frisenda R, Castellanos-Gomez A. Superlattices based on van der Waals 2D materials. Chem Commun (Camb) 2019; 55:11498-11510. [PMID: 31483427 DOI: 10.1039/c9cc04919c] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Two-dimensional (2D) materials exhibit a number of improved mechanical, optical, and electronic properties compared to their bulk counterparts. The absence of dangling bonds in the cleaved surfaces of these materials allows combining different 2D materials into van der Waals heterostructures to fabricate p-n junctions, photodetectors, and 2D-2D ohmic contacts that show unexpected performances. These intriguing results are regularly summarized in comprehensive reviews. A strategy to tailor their properties even further and to observe novel quantum phenomena consists in the fabrication of superlattices whose unit cell is formed either by two dissimilar 2D materials or by a 2D material subjected to a periodic perturbation, each component contributing with different characteristics. Furthermore, in a 2D material-based superlattice, the interlayer interaction between the layers mediated by van der Waals forces constitutes a key parameter to tune the global properties of the superlattice. The above-mentioned factors reflect the potential to devise countless combinations of van der Waals 2D material-based superlattices. In the present feature article, we explain in detail the state-of-the-art of 2D material-based superlattices and describe the different methods to fabricate them, classified as vertical stacking, intercalation with atoms or molecules, moiré patterning, strain engineering and lithographic design. We also aim to highlight some of the specific applications of each type of superlattices.
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Affiliation(s)
- Yu Kyoung Ryu
- Materials Science Factory, Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Madrid, E-28049, Spain.
| | - Riccardo Frisenda
- Materials Science Factory, Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Madrid, E-28049, Spain.
| | - Andres Castellanos-Gomez
- Materials Science Factory, Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Madrid, E-28049, Spain.
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17
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Yang WJ, Park H, Kim DS, Ha T, Park SJ, Ahn M, Kim JH, Kwon YK, Cho MH. Phase-change like process through bond switching in distorted and resonantly bonded crystal. Sci Rep 2019; 9:12816. [PMID: 31492917 PMCID: PMC6731313 DOI: 10.1038/s41598-019-49270-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 08/07/2019] [Indexed: 11/08/2022] Open
Abstract
Although some methods to improve phase-change memory efficiency have been proposed, an effective experimental approach to induce a phase-change like process without external heat energy has not yet been reported. Herein we have shown that GeTe is a prototype phase-change material, which can exhibit a non-thermal phase-change-like process under uniaxial stress. Due to its structural characteristics like directional structural instability and resonance bonding under 1% uniaxial stress, we observed that bond switching in the GeTe film between short and long bonds is possible. Due to this phase change, GeTe displays the same phase-change as crystal layer rotation. Crystal layer rotation has not been observed in the conventional phase change process using intermediate states, but it is related to the structural characteristics required for maintaining local coordination. Moreover, since the resonance bonding characteristics are effectively turned off upon applying uniaxial stress, the high-frequency dielectric constant can be significantly decreased. Our results also show that the most significant process in the non-thermal phase transition of phase-change materials is the modulation of the lattice relaxation process after the initial perturbation, rather than the method inducing the perturbation itself. Finally, these consequences suggest that a new type of phase-change memory is possible through changes in the optical properties under stress.
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Affiliation(s)
- Won Jun Yang
- Department of Physics and Applied Physics, Yonsei University, Seoul, 03722, Republic of Korea
| | - Hanjin Park
- Department of Physics and Research Institute for Basic Sciences, Kyung Hee University, Seoul, 02447, Republic of Korea
| | - Da Sol Kim
- Department of Physics and Applied Physics, Yonsei University, Seoul, 03722, Republic of Korea
| | - Taewoo Ha
- Department of Physics and Applied Physics, Yonsei University, Seoul, 03722, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Seung Jong Park
- Department of Physics and Applied Physics, Yonsei University, Seoul, 03722, Republic of Korea
| | - Min Ahn
- Department of Physics and Applied Physics, Yonsei University, Seoul, 03722, Republic of Korea
| | - Jae Hoon Kim
- Department of Physics and Applied Physics, Yonsei University, Seoul, 03722, Republic of Korea
| | - Young-Kyun Kwon
- Department of Physics and Research Institute for Basic Sciences, Kyung Hee University, Seoul, 02447, Republic of Korea.
| | - Mann-Ho Cho
- Department of Physics and Applied Physics, Yonsei University, Seoul, 03722, Republic of Korea.
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18
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Affiliation(s)
- Robert E Simpson
- Engineering Product Development, Singapore University of Technology and Design, Singapore, Singapore.
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19
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Hou W, Azizimanesh A, Sewaket A, Peña T, Watson C, Liu M, Askari H, Wu SM. Strain-based room-temperature non-volatile MoTe 2 ferroelectric phase change transistor. NATURE NANOTECHNOLOGY 2019; 14:668-673. [PMID: 31182837 DOI: 10.1038/s41565-019-0466-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Accepted: 04/26/2019] [Indexed: 06/09/2023]
Abstract
The primary mechanism of operation of almost all transistors today relies on the electric-field effect in a semiconducting channel to tune its conductivity from the conducting 'on' state to a non-conducting 'off' state. As transistors continue to scale down to increase computational performance, physical limitations from nanoscale field-effect operation begin to cause undesirable current leakage, which is detrimental to the continued advancement of computing1,2. Using a fundamentally different mechanism of operation, we show that through nanoscale strain engineering with thin films and ferroelectrics the transition metal dichalcogenide MoTe2 can be reversibly switched with electric-field-induced strain between the 1T'-MoTe2 (semimetallic) phase to a semiconducting MoTe2 phase in a field-effect transistor geometry. This alternative mechanism for transistor switching sidesteps all the static and dynamic power consumption problems in conventional field-effect transistors3,4. Using strain, we achieve large non-volatile changes in channel conductivity (Gon/Goff ≈ 107 versus Gon/Goff ≈ 0.04 in the control device) at room temperature. Ferroelectric devices offer the potential to reach sub-nanosecond non-volatile strain switching at the attojoule/bit level5-7, with immediate applications in ultrafast low-power non-volatile logic and memory8 while also transforming the landscape of computational architectures because conventional power, speed and volatility considerations for microelectronics may no longer exist.
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Affiliation(s)
- Wenhui Hou
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
| | - Ahmad Azizimanesh
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
| | - Arfan Sewaket
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
| | - Tara Peña
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
| | - Carla Watson
- Department of Physics and Astronomy, University of Rochester, Rochester, NY, USA
| | - Ming Liu
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Hesam Askari
- Department of Mechanical Engineering, University of Rochester, Rochester, NY, USA
| | - Stephen M Wu
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA.
- Department of Physics and Astronomy, University of Rochester, Rochester, NY, USA.
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20
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Mondal R, Aihara Y, Saito Y, Fons P, Kolobov AV, Tominaga J, Hase M. Topological Phase Buried in a Chalcogenide Superlattice Monitored by Helicity-Dependent Kerr Measurement. ACS APPLIED MATERIALS & INTERFACES 2018; 10:26781-26786. [PMID: 30019581 DOI: 10.1021/acsami.8b07974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Chalcogenide superlattices (SLs), formed by the alternate stacking of GeTe and Sb2Te3 layers, also referred to as interfacial phase-change memory (iPCM), are a leading candidate for spin-based memory device applications. Theoretically, the iPCM structure has been predicted to form a three-dimensional topological insulator or Dirac semimetal phase depending on the constituent layer thicknesses. Here, we experimentally investigate the topological insulating nature of chalcogenide SLs using a helicity-dependent time-resolved Kerr measurement. The helicity-dependent Kerr signal is observed to exhibit a four-cycle oscillation with π/2 periodicity, suggesting the existence of a Dirac-like cone in some chalcogenide SLs. Furthermore, we found that increasing the thickness of the GeTe layer dramatically changed the periodicity, indicating a phase transition from a Dirac semimetal into a trivial insulator. Our results demonstrate that thickness-tuned chalcogenide SLs can play an important role in the manipulation of topological states, which may open up new possibilities for spintronic devices based on chalcogenide SLs.
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Affiliation(s)
- Richarj Mondal
- Division of Applied Physics, Faculty of Pure and Applied Sciences , University of Tsukuba , 1-1-1 Tennodai , Tsukuba 305-8573 , Japan
| | - Yuki Aihara
- Division of Applied Physics, Faculty of Pure and Applied Sciences , University of Tsukuba , 1-1-1 Tennodai , Tsukuba 305-8573 , Japan
| | - Yuta Saito
- Nanoelectronics Research Institute , National Institute of Advanced Industrial Science and Technology , Tsukuba Central 5, 1-1-1 Higashi , Tsukuba 305-8565 , Japan
| | - Paul Fons
- Nanoelectronics Research Institute , National Institute of Advanced Industrial Science and Technology , Tsukuba Central 5, 1-1-1 Higashi , Tsukuba 305-8565 , Japan
| | - Alexander V Kolobov
- Nanoelectronics Research Institute , National Institute of Advanced Industrial Science and Technology , Tsukuba Central 5, 1-1-1 Higashi , Tsukuba 305-8565 , Japan
| | - Junji Tominaga
- Nanoelectronics Research Institute , National Institute of Advanced Industrial Science and Technology , Tsukuba Central 5, 1-1-1 Higashi , Tsukuba 305-8565 , Japan
| | - Muneaki Hase
- Division of Applied Physics, Faculty of Pure and Applied Sciences , University of Tsukuba , 1-1-1 Tennodai , Tsukuba 305-8573 , Japan
- Nanoelectronics Research Institute , National Institute of Advanced Industrial Science and Technology , Tsukuba Central 5, 1-1-1 Higashi , Tsukuba 305-8565 , Japan
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21
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Kowalczyk P, Hippert F, Bernier N, Mocuta C, Sabbione C, Batista-Pessoa W, Noé P. Impact of Stoichiometry on the Structure of van der Waals Layered GeTe/Sb 2 Te 3 Superlattices Used in Interfacial Phase-Change Memory (iPCM) Devices. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1704514. [PMID: 29761644 DOI: 10.1002/smll.201704514] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 03/30/2018] [Indexed: 06/08/2023]
Abstract
Van der Waals layered GeTe/Sb2 Te3 superlattices (SLs) have demonstrated outstanding performances for use in resistive memories in so-called interfacial phase-change memory (iPCM) devices. GeTe/Sb2 Te3 SLs are made by periodically stacking ultrathin GeTe and Sb2 Te3 crystalline layers. The mechanism of the resistance change in iPCM devices is still highly debated. Recent experimental studies on SLs grown by molecular beam epitaxy or pulsed laser deposition indicate that the local structure does not correspond to any of the previously proposed structural models. Here, a new insight is given into the complex structure of prototypical GeTe/Sb2 Te3 SLs deposited by magnetron sputtering, which is the used industrial technique for SL growth in iPCM devices. X-ray diffraction analysis shows that the structural quality of the SL depends critically on its stoichiometry. Moreover, high-angle annular dark-field-scanning transmission electron microscopy analysis of the local atomic order in a perfectly stoichiometric SL reveals the absence of GeTe layers, and that Ge atoms intermix with Sb atoms in, for instance, Ge2 Sb2 Te5 blocks. This result shows that an alternative structural model is required to explain the origin of the electrical contrast and the nature of the resistive switching mechanism observed in iPCM devices.
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Affiliation(s)
- Philippe Kowalczyk
- Université Grenoble Alpes, CEA, LETI, 17, rue des Martyrs, F 38054, Grenoble Cedex 9, France
- Université Grenoble Alpes, CNRS, LTM, 17, rue des Martyrs, F 38054, Grenoble Cedex 9, France
| | - Françoise Hippert
- LNCMI-EMFL-CNRS, Université Grenoble Alpes, INSA, UPS, 25, rue des Martyrs, F 38042, Grenoble Cedex 9, France
| | - Nicolas Bernier
- Université Grenoble Alpes, CEA, LETI, 17, rue des Martyrs, F 38054, Grenoble Cedex 9, France
| | - Cristian Mocuta
- Synchrotron SOLEIL l'Orme des Merisiers, Saint-Aubin - BP 48, F-91192, Gif-sur-Yvette Cedex, France
| | - Chiara Sabbione
- Université Grenoble Alpes, CEA, LETI, 17, rue des Martyrs, F 38054, Grenoble Cedex 9, France
| | - Walter Batista-Pessoa
- Université Grenoble Alpes, CEA, LETI, 17, rue des Martyrs, F 38054, Grenoble Cedex 9, France
| | - Pierre Noé
- Université Grenoble Alpes, CEA, LETI, 17, rue des Martyrs, F 38054, Grenoble Cedex 9, France
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22
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Evazzade I, Lobzenko IP, Saadatmand D, Korznikova EA, Zhou K, Liu B, Dmitriev SV. Graphene nanoribbon as an elastic damper. NANOTECHNOLOGY 2018; 29:215704. [PMID: 29488901 DOI: 10.1088/1361-6528/aab2f4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Heterostructures composed of dissimilar two-dimensional nanomaterials can have nontrivial physical and mechanical properties which are potentially useful in many applications. Interestingly, in some cases, it is possible to create heterostructures composed of weakly and strongly stretched domains with the same chemical composition, as has been demonstrated for some polymer chains, DNA, and intermetallic nanowires supporting this effect of two-phase stretching. These materials, at relatively strong tension forces, split into domains with smaller and larger tensile strains. Within this region, average strain increases at constant tensile force due to the growth of the domain with the larger strain, at the expense of the domain with smaller strain. Here, the two-phase stretching phenomenon is described for graphene nanoribbons with the help of molecular dynamics simulations. This unprecedented feature of graphene that is revealed in our study is related to the peculiarities of nucleation and the motion of the domain walls separating the domains of different elastic strain. It turns out that the loading-unloading curves exhibit a hysteresis-like behavior due to the energy dissipation during the domain wall nucleation and motion. Here, we put forward the idea of implementing graphene nanoribbons as elastic dampers, efficiently converting mechanical strain energy into heat during cyclic loading-unloading through elastic extension where domains with larger and smaller strains coexist. Furthermore, in the regime of two-phase stretching, graphene nanoribbon is a heterostructure for which the fraction of domains with larger and smaller strain, and consequently its physical and mechanical properties, can be tuned in a controllable manner by applying elastic strain and/or heat.
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Affiliation(s)
- Iman Evazzade
- Department of Physics, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
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23
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Behera JK, Zhou X, Ranjan A, Simpson RE. Sb 2Te 3 and Its Superlattices: Optimization by Statistical Design. ACS APPLIED MATERIALS & INTERFACES 2018; 10:15040-15050. [PMID: 29649865 DOI: 10.1021/acsami.8b02100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The objective of this work is to demonstrate the usefulness of fractional factorial design for optimizing the crystal quality of chalcogenide van der Waals (vdW) crystals. We statistically analyze the growth parameters of highly c axis oriented Sb2Te3 crystals and Sb2Te3-GeTe phase change vdW heterostructured superlattices. The statistical significance of the growth parameters of temperature, pressure, power, buffer materials, and buffer layer thickness was found by fractional factorial design and response surface analysis. Temperature, pressure, power, and their second-order interactions are the major factors that significantly influence the quality of the crystals. Additionally, using tungsten rather than molybdenum as a buffer layer significantly enhances the crystal quality. Fractional factorial design minimizes the number of experiments that are necessary to find the optimal growth conditions, resulting in an order of magnitude improvement in the crystal quality. We highlight that statistical design of experiment methods, which is more commonly used in product design, should be considered more broadly by those designing and optimizing materials.
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Affiliation(s)
- Jitendra K Behera
- ACTA Lab , Singapore University of Technology and Design , 8 Somapah Road , 487372 Singapore
| | - Xilin Zhou
- ACTA Lab , Singapore University of Technology and Design , 8 Somapah Road , 487372 Singapore
| | - Alok Ranjan
- Singapore University of Technology and Design , 8 Somapah Road , 487372 Singapore
| | - Robert E Simpson
- ACTA Lab , Singapore University of Technology and Design , 8 Somapah Road , 487372 Singapore
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24
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Wang J, Ronneberger I, Zhou L, Lu L, Deringer VL, Zhang B, Tian L, Du H, Jia C, Qian X, Wuttig M, Mazzarello R, Zhang W. Unconventional two-dimensional germanium dichalcogenides. NANOSCALE 2018; 10:7363-7368. [PMID: 29637969 DOI: 10.1039/c8nr01747f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The recently discovered two-dimensional (2D) group IV chalcogenides attract much attention owing to their novel electronic and photonic properties. All the reported materials of this class favor (distorted) octahedral coordination via p bonding; by contrast, in the dichalcogenides where the bonding tendency approaches sp3, no corresponding 2D phase has been realized so far. Here, by engineering the composition of a chalcogenide heterostructure, the hitherto elusive GeTe2 is experimentally observed in a confined 2D environment. Density functional theory simulations predict the existence of a freestanding monolayer of octahedrally coordinated GeTe2 under tensile strain, and the existence of GeSe2 and GeS2 in the same form under equilibrium conditions. These 2D germanium dichalcogenides are either metallic or narrow gap semiconducting, and may lead to new applications in nanoscale electronics.
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Affiliation(s)
- Jiangjing Wang
- Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
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25
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Vermeulen PA, Mulder J, Momand J, Kooi BJ. Strain engineering of van der Waals heterostructures. NANOSCALE 2018; 10:1474-1480. [PMID: 29303191 DOI: 10.1039/c7nr07607j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Modifying the strain state of solids allows control over a plethora of functional properties. The weak interlayer bonding in van der Waals (vdWaals) materials such as graphene, hBN, MoS2, and Bi2Te3 might seem to exclude strain engineering, since strain would immediately relax at the vdWaals interfaces. Here we present direct observations of the contrary by showing growth of vdWaals heterostructures with persistent in-plane strains up to 5% and we show that strain relaxation follows a not yet reported process distinctly different from strain relaxation in three-dimensionally bonded (3D) materials. For this, 2D bonded Bi2Te3-Sb2Te3 and 2D/3D bonded Bi2Te3-GeTe multilayered films are grown using Pulsed Laser Deposition (PLD) and their structure is monitored in situ using Reflective High Energy Electron Diffraction (RHEED) and post situ analysis is performed using Transmission Electron Microscopy (TEM). Strain relaxation is modeled and found to solely depend on the layer being grown and its initial strain. This insight demonstrates that strain engineering of 2D bonded heterostructures obeys different rules than hold for epitaxial 3D materials and opens the door to precise tuning of the strain state of the individual layers to optimize functional performance of vdWaals heterostructures.
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Affiliation(s)
- Paul A Vermeulen
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
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26
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Yang Z, Xu M, Cheng X, Tong H, Miao X. Manipulation of dangling bonds of interfacial states coupled in GeTe-rich GeTe/Sb 2Te 3 superlattices. Sci Rep 2017; 7:17353. [PMID: 29229978 PMCID: PMC5725461 DOI: 10.1038/s41598-017-17671-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 11/28/2017] [Indexed: 11/09/2022] Open
Abstract
Superlattices consisting of stacked nano-sized GeTe and Sb2Te3 blocks have attracted considerable attention owing to their potential for an efficient non-melting switching mechanism, associated with complex bonding between blocks. Here, we propose possible atomic models for the superlattices, characterized by different interfacial bonding types. Based on interplanar distances extracted from ab initio calculations and electron diffraction measurements, we reveal possible intercalation of dangling bonds as the GeTe content in the superlattice increases. The dangling bonds were further confirmed by X-ray photoelectron spectroscopy, anisotropic temperature dependent resistivity measurements down to 2 K and magnetotransport analysis. Changes of partially coherent decoupled topological surfaces states upon dangling bonds varying contributed to the switching mechanism. Furthermore, the topological surface states controlled by changing the bonding between stacking blocks may be optimized for multi-functional applications.
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Affiliation(s)
- Zhe Yang
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Ming Xu
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Xiaomin Cheng
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Hao Tong
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China.
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Xiangshui Miao
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
- Wuhan National High Magnetic Field Centre, Huazhong University of Science and Technology, Wuhan, 430074, China
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27
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Saito Y, Fons P, Makino K, Mitrofanov KV, Uesugi F, Takeguchi M, Kolobov AV, Tominaga J. Compositional tuning in sputter-grown highly-oriented Bi-Te films and their optical and electronic structures. NANOSCALE 2017; 9:15115-15121. [PMID: 28972624 DOI: 10.1039/c7nr04709f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Growth of Bi-Te films by helicon-wave magnetron sputtering is systematically explored using alloy targets. The film compositions obtained are found to strongly depend on both the sputtering and antenna-coil powers. The obtainable film compositions range from Bi55Te45 to Bi43Te57 when a Bi2Te3 alloy target is used, and from Bi42Te58 to Bi40Te60 (Bi2Te3) for a Te-rich Bi30Te70 target. All films show strong orientation of the van der Waals layers (00l planes) parallel to the substrate. The atomic level stacking of Bi2Te3 quintuple and Bi bi-layers has been directly observed by high resolution transmission electron microscopy. Band structure simulations reveal that Bi-rich Bi4Te3 bulk is a zero band gap semimetal with a Dirac cone at the Gamma point when spin-orbit coupling is included. Optical measurements also confirm that the material has a zero band gap. The tunability of the composition and the topological insulating properties of the layers will enable the use of these materials for future electronics applications on an industrial scale.
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Affiliation(s)
- Yuta Saito
- Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 5, 1-1-1 Higashi, Tsukuba 305-8565, Japan.
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28
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Kolobov AV, Fons P, Saito Y, Tominaga J. Atomic Reconfiguration of van der Waals Gaps as the Key to Switching in GeTe/Sb 2Te 3 Superlattices. ACS OMEGA 2017; 2:6223-6232. [PMID: 31457867 PMCID: PMC6644333 DOI: 10.1021/acsomega.7b00812] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Accepted: 09/12/2017] [Indexed: 05/09/2023]
Abstract
Nonvolatile memory, of which phase-change memory (PCM) is a leading technology, is currently a key element of various electronics and portable systems. An important step in the development of conceptually new devices is the class of van der Waals (vdW)-bonded GeTe/Sb2Te3 superlattices (SLs). With their order of magnitude faster switching rates and lower energy consumption compared to those of alloy-based devices, they are widely regarded as the next step in the implementation of PCM. In contrast to conventional PCM, where the SET and RESET states arise from the crystalline and amorphous phases, in SLs, both the SET and RESET states remain crystalline. In an earlier work, the superior performance of SLs was attributed to the reduction of entropic losses associated with the one-dimensional motion of interfacial Ge atoms located in the vicinity of Sb2Te3 quintuple layers. Subsequent experimental studies using transmission electron microscopy revealed that GeTe and Sb2Te3 blocks strongly intermix during the growth of the GeTe phase, challenging the original proposal but at the same time raising new fundamental issues. In this work, we propose a new approach to switching in SLs associated with the reconfiguration of vdW gaps accompanied by local deviation of stoichiometry from the GeTe/Sb2Te3 quasibinary alloys. The model resolves in a natural way the existing controversies, explains the large conductivity contrast between the SET and RESET crystalline states, is not compromised by Ge/Sb intermixing, and provides a new perspective for the industrial development of memory devices based on such SLs. The proposed concept of vdW gap reconfiguration may also be applicable to designing a broad variety of engineered two-dimensional vdW solids.
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29
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Wang JJ, Xu YZ, Mazzarello R, Wuttig M, Zhang W. A Review on Disorder-Driven Metal-Insulator Transition in Crystalline Vacancy-Rich GeSbTe Phase-Change Materials. MATERIALS 2017; 10:ma10080862. [PMID: 28773222 PMCID: PMC5578228 DOI: 10.3390/ma10080862] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 07/23/2017] [Accepted: 07/25/2017] [Indexed: 12/14/2022]
Abstract
Metal-insulator transition (MIT) is one of the most essential topics in condensed matter physics and materials science. The accompanied drastic change in electrical resistance can be exploited in electronic devices, such as data storage and memory technology. It is generally accepted that the underlying mechanism of most MITs is an interplay of electron correlation effects (Mott type) and disorder effects (Anderson type), and to disentangle the two effects is difficult. Recent progress on the crystalline Ge₁Sb₂Te₄ (GST) compound provides compelling evidence for a disorder-driven MIT. In this work, we discuss the presence of strong disorder in GST, and elucidate its effects on electron localization and transport properties. We also show how the degree of disorder in GST can be reduced via thermal annealing, triggering a disorder-driven metal-insulator transition. The resistance switching by disorder tuning in crystalline GST may enable novel multilevel data storage devices.
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Affiliation(s)
- Jiang-Jing Wang
- Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Ya-Zhi Xu
- Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Riccardo Mazzarello
- Institute for Theoretical Solid-State Physics, JARA-FIT and JARA-HPC, RWTH Aachen University, 52074 Aachen, Germany.
| | - Matthias Wuttig
- Institute of Physics IA, JARA-FIT and JARA-HPC, RWTH Aachen University, 52074 Aachen, Germany.
| | - Wei Zhang
- Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China.
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30
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Krbal M, Bartak J, Kolar J, Prytuliak A, Kolobov AV, Fons P, Bezacier L, Hanfland M, Tominaga J. Pressure-Induced Phase Transitions in GeTe-Rich Ge-Sb-Te Alloys across the Rhombohedral-to-Cubic Transitions. Inorg Chem 2017; 56:7687-7693. [PMID: 28654250 DOI: 10.1021/acs.inorgchem.7b00163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We demonstrate that pressure-induced amorphization in Ge-Sb-Te alloys across the ferroelectric-paraelectric transition can be represented as a mixture of coherently distorted rhombohedral Ge8Sb2Te11 and randomly distorted cubic Ge4Sb2Te7 and high-temperature Ge8Sb2Te11 phases. While coherent distortion in Ge8Sb2Te11 does not prevent the crystalline state from collapsing into its amorphous counterpart in a similar manner to pure GeTe, the pressure-amorphized Ge8Sb2Te11 phase begins to revert to the crystalline cubic phase at ∼9 GPa in contrast to Ge4Sb2Te7, which remains amorphous under ambient conditions when gradually decompressed from 40 GPa. Moreover, experimentally, it was observed that pressure-induced amorphization in Ge8Sb2Te11 is a temperature-dependent process. Ge8Sb2Te11 transforms into the amorphous phase at ∼27.5 and 25.2 GPa at room temperature and 408 K, respectively, and completely amorphizes at 32 GPa at 408 K, while some crystalline texture could be seen until 38 GPa (the last measurement point) at room temperature. To understand the origins of the temperature dependence of the pressure-induced amorphization process, density functional theory calculations were performed for compositions along the (GeTe)x - (Sb2Te3)1-x tie line under large hydrostatic pressures. The calculated results agreed well with the experimental data.
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Affiliation(s)
- Milos Krbal
- Faculty of Chemical Technology, Center of Materials and Nanotechnologies, University of Pardubice , Legions Square 565, 530 02 Pardubice, Czech Republic
| | | | | | | | - Alexander V Kolobov
- Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology 1-1-1 Higashi , Tsukuba 305-8562, Ibaraki Japan
| | - Paul Fons
- Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology 1-1-1 Higashi , Tsukuba 305-8562, Ibaraki Japan
| | - Lucile Bezacier
- European Synchrotron Radiation Facility , 6 rue Jules Horowitz, Boîte Postale 220, F38043 Grenoble, France
| | - Michael Hanfland
- European Synchrotron Radiation Facility , 6 rue Jules Horowitz, Boîte Postale 220, F38043 Grenoble, France
| | - Junji Tominaga
- Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology 1-1-1 Higashi , Tsukuba 305-8562, Ibaraki Japan
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31
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Nakamura H, Rungger I, Sanvito S, Inoue N, Tominaga J, Asai Y. Resistive switching mechanism of GeTe-Sb 2Te 3 interfacial phase change memory and topological properties of embedded two-dimensional states. NANOSCALE 2017; 9:9386-9395. [PMID: 28657077 DOI: 10.1039/c7nr03495d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A theoretical study of an interfacial phase change memory made of a GeTe-Sb2Te3 superlattice with W electrodes is presented to identify the high and low resistance states and the switching mechanism. The ferro structure of the GeTe layer block in the Te-Ge-Te-Ge sequence can be in the low resistance state only if the SET/RESET mode consists of a two step dynamical process, corresponding to a vertical flip of the Ge layer with respect to the Te layer, followed by lateral motion driven by thermal relaxation. The importance of spin-orbit coupling at the GeTe/Sb2Te3 interface to the "bias polarity-dependent" SET/RESET operation is shown, and an analysis of the two-dimensional states confined at the GeTe/Sb2Te3 interface inside the resistive switching layer is presented. Our results allow us to propose a phase diagram for the transition from a topologically nontrivial to a trivial gap state of these two-dimensional compounds.
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Affiliation(s)
- Hisao Nakamura
- CD-FMat, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba Central 2, Tsukuba, Ibaraki 305-8568, Japan.
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32
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Liu W, Xu Q, Cui W, Zhu C, Qi Y. CO
2
‐Assisted Fabrication of Two‐Dimensional Amorphous Molybdenum Oxide Nanosheets for Enhanced Plasmon Resonances. Angew Chem Int Ed Engl 2017; 56:1600-1604. [DOI: 10.1002/anie.201610708] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Wei Liu
- College of Materials Science and EngineeringZhengzhou University Zhengzhou 450052 China
| | - Qun Xu
- College of Materials Science and EngineeringZhengzhou University Zhengzhou 450052 China
| | - Weili Cui
- College of Materials Science and EngineeringZhengzhou University Zhengzhou 450052 China
| | - Chuanhui Zhu
- College of Materials Science and EngineeringZhengzhou University Zhengzhou 450052 China
| | - Yuhang Qi
- College of Materials Science and EngineeringZhengzhou University Zhengzhou 450052 China
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33
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Liu W, Xu Q, Cui W, Zhu C, Qi Y. CO2-Assisted Fabrication of Two-Dimensional Amorphous Molybdenum Oxide Nanosheets for Enhanced Plasmon Resonances. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201610708] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Wei Liu
- College of Materials Science and Engineering; Zhengzhou University; Zhengzhou 450052 China
| | - Qun Xu
- College of Materials Science and Engineering; Zhengzhou University; Zhengzhou 450052 China
| | - Weili Cui
- College of Materials Science and Engineering; Zhengzhou University; Zhengzhou 450052 China
| | - Chuanhui Zhu
- College of Materials Science and Engineering; Zhengzhou University; Zhengzhou 450052 China
| | - Yuhang Qi
- College of Materials Science and Engineering; Zhengzhou University; Zhengzhou 450052 China
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34
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Atomic Layering, Intermixing and Switching Mechanism in Ge-Sb-Te based Chalcogenide Superlattices. Sci Rep 2016; 6:37325. [PMID: 27853289 PMCID: PMC5112535 DOI: 10.1038/srep37325] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 10/24/2016] [Indexed: 11/08/2022] Open
Abstract
GeSbTe-based chalcogenide superlattice (CSLs) phase-change memories consist of GeSbTe layer blocks separated by van der Waals bonding gaps. Recent high resolution electron microscopy found two types of disorder in CSLs, a chemical disorder within individual layers, and SbTe bilayer stacking faults connecting one block to an adjacent block which allows individual block heights to vary. The disorder requires a generalization of the previous switching models developed for CSL systems. Density functional calculations are used to describe the stability of various types of intra-layer disorder, how the block heights can vary by means of SbTe-based stacking faults and using a vacancy-mediated kink motion, and also to understand the nature of the switching process in more chemically disordered CSLs.
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35
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Kalikka J, Zhou X, Behera J, Nannicini G, Simpson RE. Evolutionary design of interfacial phase change van der Waals heterostructures. NANOSCALE 2016; 8:18212-18220. [PMID: 27759127 DOI: 10.1039/c6nr05539g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We use an evolutionary algorithm to explore the design space of hexagonal Ge2Sb2Te5; a van der Waals layered two dimensional crystal heterostructure. The Ge2Sb2Te5 structure is more complicated than previously thought. Predominant features include layers of Ge3Sb2Te6 and Ge1Sb2Te4 two dimensional crystals that interact through Te-Te van der Waals bonds. Interestingly, (Ge/Sb)-Te-(Ge/Sb)-Te alternation is a common feature for the most stable structures of each generation's evolution. This emergent rule provides an important structural motif that must be included in the design of high performance Sb2Te3-GeTe van der Waals heterostructure superlattices with interfacial atomic switching capability. The structures predicted by the algorithm agree well with experimental measurements on highly oriented, and single crystal Ge2Sb2Te5 samples. By analysing the evolutionary algorithm optimised structures, we show that diffusive atomic switching is probable by Ge atoms undergoing a transition at the van der Waals interface from layers of Ge3Sb2Te6 to Ge1Sb2Te4 thus producing two blocks of Ge2Sb2Te5. Evolutionary methods present an efficient approach to explore the enormous multi-dimensional design parameter space of van der Waals bonded heterostructure superlattices.
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Affiliation(s)
- Janne Kalikka
- Singapore University of Technology and Design, 8 Somapah Road, Singapore.
| | - Xilin Zhou
- Singapore University of Technology and Design, 8 Somapah Road, Singapore.
| | - Jitendra Behera
- Singapore University of Technology and Design, 8 Somapah Road, Singapore.
| | | | - Robert E Simpson
- Singapore University of Technology and Design, 8 Somapah Road, Singapore.
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36
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Zhou X, Du Y, Behera JK, Wu L, Song Z, Simpson RE. Oxygen Tuned Local Structure and Phase-Change Performance of Germanium Telluride. ACS APPLIED MATERIALS & INTERFACES 2016; 8:20185-20191. [PMID: 27430363 DOI: 10.1021/acsami.6b05071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The effect of oxygen on the local structure of Ge atoms in GeTe-O materials has been investigated. Oxygen leads to a significant modification to the vibrational modes of Ge octahedra, which results from a decrease in its coordination. We find that a defective octahedral Ge network is the crucial fingerprint for rapid and reversible structural transitions in GeTe-based phase change materials. The appearance of oxide Raman modes confirms phase separation into GeO and TeO at high level O doping. Counterintuitively, despite the increase in crystallization temperature of oxygen doped GeTe-O phase change materials, when GeTe-O materials are used in electrical phase change memory cells, the electrical switching energy is lower than the pure GeTe material. This switching energy reduction is ascribed to the smaller change in volume, and therefore smaller enthalpy change, for the oxygen doped GeTe materials.
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Affiliation(s)
- Xilin Zhou
- ACTA Lab, Singapore University of Technology and Design , 8 Somapah Road, 487372, Singapore
| | - Yonghua Du
- Institute of Chemical and Engineering Sciences, A*STAR , 1 Pesek Road, Jurong Island 627833, Singapore
| | - Jitendra K Behera
- ACTA Lab, Singapore University of Technology and Design , 8 Somapah Road, 487372, Singapore
| | - Liangcai Wu
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences , 200050 Shanghai, China
| | - Zhitang Song
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences , 200050 Shanghai, China
| | - Robert E Simpson
- ACTA Lab, Singapore University of Technology and Design , 8 Somapah Road, 487372, Singapore
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