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Yu Y, Turkowski V, Hachtel JA, Puretzky AA, Ievlev AV, Din NU, Harris SB, Iyer V, Rouleau CM, Rahman TS, Geohegan DB, Xiao K. Anomalous isotope effect on the optical bandgap in a monolayer transition metal dichalcogenide semiconductor. SCIENCE ADVANCES 2024; 10:eadj0758. [PMID: 38381831 PMCID: PMC10881028 DOI: 10.1126/sciadv.adj0758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 01/23/2024] [Indexed: 02/23/2024]
Abstract
Isotope effects have received increasing attention in materials science and engineering because altering isotopes directly affects phonons, which can affect both thermal properties and optoelectronic properties of conventional semiconductors. However, how isotopic mass affects the optoelectronic properties in 2D semiconductors remains unclear because of measurement uncertainties resulting from sample heterogeneities. Here, we report an anomalous optical bandgap energy red shift of 13 (±7) milli-electron volts as mass of Mo isotopes is increased in laterally structured 100MoS2-92MoS2 monolayers grown by a two-step chemical vapor deposition that mitigates the effects of heterogeneities. This trend, which is opposite to that observed in conventional semiconductors, is explained by many-body perturbation and time-dependent density functional theories that reveal unusually large exciton binding energy renormalizations exceeding the ground-state renormalization energy due to strong coupling between confined excitons and phonons. The isotope effect on the optical bandgap reported here provides perspective on the important role of exciton-phonon coupling in the physical properties of two-dimensional materials.
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Affiliation(s)
- Yiling Yu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Volodymyr Turkowski
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
| | - Jordan A. Hachtel
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Alexander A. Puretzky
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Anton V. Ievlev
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Naseem U. Din
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
| | - Sumner B. Harris
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Vasudevan Iyer
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Christopher M. Rouleau
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Talat S. Rahman
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
| | - David B. Geohegan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Kai Xiao
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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2
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Dang C, Chou JP, Dai B, Chou CT, Yang Y, Fan R, Lin W, Meng F, Hu A, Zhu J, Han J, Minor AM, Li J, Lu Y. Achieving large uniform tensile elasticity in microfabricated diamond. Science 2021; 371:76-78. [PMID: 33384375 DOI: 10.1126/science.abc4174] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 11/23/2020] [Indexed: 11/02/2022]
Abstract
Diamond is not only the hardest material in nature, but is also an extreme electronic material with an ultrawide bandgap, exceptional carrier mobilities, and thermal conductivity. Straining diamond can push such extreme figures of merit for device applications. We microfabricated single-crystalline diamond bridge structures with ~1 micrometer length by ~100 nanometer width and achieved sample-wide uniform elastic strains under uniaxial tensile loading along the [100], [101], and [111] directions at room temperature. We also demonstrated deep elastic straining of diamond microbridge arrays. The ultralarge, highly controllable elastic strains can fundamentally change the bulk band structures of diamond, including a substantial calculated bandgap reduction as much as ~2 electron volts. Our demonstration highlights the immense application potential of deep elastic strain engineering for photonics, electronics, and quantum information technologies.
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Affiliation(s)
- Chaoqun Dang
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong
| | - Jyh-Pin Chou
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong.,Department of Physics, National Changhua University of Education, Changhua 50007, Taiwan
| | - Bing Dai
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin 150080, China
| | - Chang-Ti Chou
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan
| | - Yang Yang
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, and Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Rong Fan
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong
| | - Weitong Lin
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong
| | - Fanling Meng
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Alice Hu
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong. .,Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong
| | - Jiaqi Zhu
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin 150080, China.
| | - Jiecai Han
- National Key Laboratory of Science and Technology on Advanced Composites in Special Environments, Harbin Institute of Technology, Harbin 150080, China
| | - Andrew M Minor
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, and Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA
| | - Ju Li
- Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Yang Lu
- Department of Mechanical Engineering, City University of Hong Kong, Kowloon, Hong Kong. .,Department of Materials Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong.,Nano-Manufacturing Laboratory (NML), Shenzhen Research Institute of City University of Hong Kong, Shenzhen, 518057, China
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3
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Shu G, Ralchenko VG, Bolshakov AP, Zavedeev EV, Khomich AA, Pivovarov PA, Ashkinazi EE, Konov VI, Dai B, Han J, Zhu J. Evolution of surface relief of epitaxial diamond films upon growth resumption by microwave plasma chemical vapor deposition. CrystEngComm 2020. [DOI: 10.1039/c9ce01933b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Homoepitaxial diamond growth may proceed with stops and resumptions to produce thick crystals. We found the resumption procedure to take place in a complex way, via a disturbance of step growth features, followed by the recovery after a certain time.
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4
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Approaching diamond's theoretical elasticity and strength limits. Nat Commun 2019; 10:5533. [PMID: 31797924 PMCID: PMC6892892 DOI: 10.1038/s41467-019-13378-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 11/01/2019] [Indexed: 11/08/2022] Open
Abstract
Diamond is the hardest natural material, but its practical strength is low and its elastic deformability extremely limited. While recent experiments have demonstrated that diamond nanoneedles can sustain exceptionally large elastic tensile strains with high tensile strengths, the size- and orientation-dependence of these properties remains unknown. Here we report maximum achievable tensile strain and strength of diamond nanoneedles with various diameters, oriented in <100>, <110> and <111> -directions, using in situ transmission electron microscopy. We show that reversible elastic deformation depends both on nanoneedle diameter and orientation. <100> -oriented nanoneedles with a diameter of 60 nm exhibit highest elastic tensile strain (13.4%) and tensile strength (125 GPa). These values are comparable with the theoretical elasticity and Griffith strength limits of diamond, respectively. Our experimental data, together with first principles simulations, indicate that maximum achievable elastic strain and strength are primarily determined by surface conditions of the nanoneedles. While diamond is the strongest natural material, it fails to reach its theoretical elasticity limits and is brittle. Here, the authors show that thin <100>-orientated diamond nanoneedles can reach diamond’s theoretical strength and elasticity limits in tension.
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Banerjee A, Bernoulli D, Zhang H, Yuen MF, Liu J, Dong J, Ding F, Lu J, Dao M, Zhang W, Lu Y, Suresh S. Ultralarge elastic deformation of nanoscale diamond. Science 2018; 360:300-302. [DOI: 10.1126/science.aar4165] [Citation(s) in RCA: 153] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 03/05/2018] [Indexed: 12/11/2022]
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Bray K, Kato H, Previdi R, Sandstrom R, Ganesan K, Ogura M, Makino T, Yamasaki S, Magyar AP, Toth M, Aharonovich I. Single crystal diamond membranes for nanoelectronics. NANOSCALE 2018; 10:4028-4035. [PMID: 29431820 DOI: 10.1039/c7nr09097h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Single crystal, nanoscale diamond membranes are highly sought after for a variety of applications including nanophotonics, nanoelectronics and quantum information science. However, so far, the availability of conductive diamond membranes has remained an unreachable goal. In this work we present a complete nanofabrication methodology for engineering high aspect ratio, electrically active single crystal diamond membranes. The membranes have large lateral directions, exceeding ∼500 × 500 μm2 and are only several hundreds of nanometers thick. We further realize vertical single crystal p-n junctions made from the diamond membranes that exhibit onset voltages of ∼10 V and a current of several mA. Moreover, we deterministically introduce optically active color centers into the membranes, and demonstrate for the first time a single crystal nanoscale diamond LED. The robust and scalable approach to engineer the electrically active single crystal diamond membranes offers new pathways for advanced nanophotonic, nanoelectronic and optomechanical devices employing diamond.
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Affiliation(s)
- Kerem Bray
- School of Mathematical and Physical Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia.
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Vuong TQP, Liu S, Van der Lee A, Cuscó R, Artús L, Michel T, Valvin P, Edgar JH, Cassabois G, Gil B. Isotope engineering of van der Waals interactions in hexagonal boron nitride. NATURE MATERIALS 2018; 17:152-158. [PMID: 29251722 DOI: 10.1038/nmat5048] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 11/01/2017] [Indexed: 05/28/2023]
Abstract
Hexagonal boron nitride is a model lamellar compound where weak, non-local van der Waals interactions ensure the vertical stacking of two-dimensional honeycomb lattices made of strongly bound boron and nitrogen atoms. We study the isotope engineering of lamellar compounds by synthesizing hexagonal boron nitride crystals with nearly pure boron isotopes (10B and 11B) compared to those with the natural distribution of boron (20 at% 10B and 80 at% 11B). On the one hand, as with standard semiconductors, both the phonon energy and electronic bandgap varied with the boron isotope mass, the latter due to the quantum effect of zero-point renormalization. On the other hand, temperature-dependent experiments focusing on the shear and breathing motions of adjacent layers revealed the specificity of isotope engineering in a layered material, with a modification of the van der Waals interactions upon isotope purification. The electron density distribution is more diffuse between adjacent layers in 10BN than in 11BN crystals. Our results open perspectives in understanding and controlling van der Waals bonding in layered materials.
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Affiliation(s)
- T Q P Vuong
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, 34095 Montpellier, France
| | - S Liu
- Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506, USA
| | - A Van der Lee
- Institut Européen des Membranes, UMR 5635 CNRS-Univ. Montpellier-ENSCM, 34095 Montpellier, France
| | - R Cuscó
- Institut Jaume Almera, Consejo Superior de Investigaciones Científicas (ICTJA-CSIC), 08028 Barcelona, Spain
| | - L Artús
- Institut Jaume Almera, Consejo Superior de Investigaciones Científicas (ICTJA-CSIC), 08028 Barcelona, Spain
| | - T Michel
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, 34095 Montpellier, France
| | - P Valvin
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, 34095 Montpellier, France
| | - J H Edgar
- Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506, USA
| | - G Cassabois
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, 34095 Montpellier, France
| | - B Gil
- Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, 34095 Montpellier, France
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8
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Prokhorov IA, Voloshin AE, Ralchenko VG, Bolshakov AP, Romanov DA, Khomich AA, Sozontov EA. X-ray diffraction characterization of epitaxial CVD diamond films with natural and isotopically modified compositions. CRYSTALLOGR REP+ 2016. [DOI: 10.1134/s1063774516060122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Mukherjee S, Watanabe H, Isheim D, Seidman DN, Moutanabbir O. Laser-Assisted Field Evaporation and Three-Dimensional Atom-by-Atom Mapping of Diamond Isotopic Homojunctions. NANO LETTERS 2016; 16:1335-1344. [PMID: 26741402 DOI: 10.1021/acs.nanolett.5b04728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
It addition to its high evaporation field, diamond is also known for its limited photoabsorption, strong covalent bonding, and wide bandgap. These characteristics have been thought for long to also complicate the field evaporation of diamond and make its control hardly achievable on the atomistic-level. Herein, we demonstrate that the unique behavior of nanoscale diamond and its interaction with pulsed laser lead to a controlled field evaporation thus enabling three-dimensional atom-by-atom mapping of diamond (12)C/(13)C homojunctions. We also show that one key element in this process is to operate the pulsed laser at high energy without letting the dc bias increase out of bounds for diamond nanotip to withstand. Herein, the role of the dc bias in evaporation of diamond is essentially to generate free charge carriers within the nanotip via impact ionization. The mobile free charges screen the internal electric field, eventually creating a hole rich surface where the pulsed laser is effectively absorbed leading to an increase in the nanotip surface temperature. The effect of this temperature on the uncertainty in the time-of-flight of an ion, the diffusion of atoms on the surface of the nanotip, is also discussed. In addition to paving the way toward a precise manipulation of isotopes in diamond-based nanoscale and quantum structures, this result also elucidates some of the basic properties of dielectric nanostructures under high electric field.
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Affiliation(s)
- Samik Mukherjee
- Department of Engineering Physics, École Polytechnique de Montréal , Montréal, C. P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7, Canada
| | - Hideyuki Watanabe
- Correlated Electronics Group, Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba Central 5, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Dieter Isheim
- Department of Materials Science and Engineering and Northwestern University Center for Atom-Probe Tomography (NUCAPT), Northwestern University , Evanston, Illinois 60208-3108, United States
| | - David N Seidman
- Department of Materials Science and Engineering and Northwestern University Center for Atom-Probe Tomography (NUCAPT), Northwestern University , Evanston, Illinois 60208-3108, United States
| | - Oussama Moutanabbir
- Department of Engineering Physics, École Polytechnique de Montréal , Montréal, C. P. 6079, Succ. Centre-Ville, Montréal, Québec H3C 3A7, Canada
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10
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Zhu Y, Withers RL, Bourgeois L, Dwyer C, Etheridge J. Direct mapping of Li-enabled octahedral tilt ordering and associated strain in nanostructured perovskites. NATURE MATERIALS 2015; 14:1142-1149. [PMID: 26322717 DOI: 10.1038/nmat4390] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 07/06/2015] [Indexed: 06/04/2023]
Abstract
Self-assembled nanostructures with periodic phase separation hold great promise for creating two- and three-dimensional superlattices with extraordinary physical properties. Understanding the mechanism(s) driving the formation of such superlattices demands an understanding of their underlying atomic structure. However, the nanoscale structural fluctuations intrinsic to these superlattices pose a new challenge for structure determination methods. Here we develop an optimized atomic-level imaging condition to measure TiO6 octahedral tilt angles, unit-cell-by-unit-cell, in perovskite-based Li(0.5-3x)Nd(0.5+x)TiO3, and thereby determine the mathematical formula governing this nanoscale superstructure. We obtain a direct real-space correlation of the octahedral tilt modulation with the superstructure geometry and lattice-parameter variations. This reveals a composition-dependent, self-ordered octahedral superlattice. Amazingly, we observe a reversible annihilation/reconstruction of the octahedral superlattice correlated with the delithiation/lithiation process in this promising Li-ion conductor. This approach to quantify local octahedral tilt and correlate it with strain can be applied to characterize complex octahedral behaviours in other advanced oxide systems.
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Affiliation(s)
- Ye Zhu
- Department of Materials Science and Engineering, Monash University, Victoria 3800, Australia
| | - Ray L Withers
- Research School of Chemistry, College of Physical and Mathematical Sciences, The Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Laure Bourgeois
- Department of Materials Science and Engineering, Monash University, Victoria 3800, Australia
- Monash Centre for Electron Microscopy, Monash University, Victoria 3800, Australia
| | - Christian Dwyer
- Department of Physics, Arizona State University, Tempe, Arizona 85287, USA
| | - Joanne Etheridge
- Department of Materials Science and Engineering, Monash University, Victoria 3800, Australia
- Monash Centre for Electron Microscopy, Monash University, Victoria 3800, Australia
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11
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Terranova ML, Orlanducci S, Rossi M, Tamburri E. Nanodiamonds for field emission: state of the art. NANOSCALE 2015; 7:5094-5114. [PMID: 25719909 DOI: 10.1039/c4nr07171a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The aim of this review is to highlight the recent advances and the main remaining challenges related to the issue of electron field emission (FE) from nanodiamonds. The roadmap for FE vacuum microelectronic devices envisages that nanodiamonds could become very important in a short time. The intrinsic properties of the nanodiamond materials indeed meet many of the requirements of cutting-edge technologies and further benefits can be obtained by tailored improvements of processing methodologies. The current strategies used to modulate the morphological and structural features of diamond to produce highly performing emitting systems are reported and discussed. The focus is on the current understanding of the FE process from nanodiamond-based materials and on the major concepts used to improve their performance. A short survey of non-conventional microsized cold cathodes based on nanodiamonds is also reported.
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Affiliation(s)
- Maria Letizia Terranova
- Dip.to di Scienze & Tecnologie Chimiche - MinimaLab, Università di Roma "Tor Vergata", Via Della Ricerca Scientifica, 00133 Rome, Italy.
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12
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Sankaran KJ, Lin YF, Jian WB, Chen HC, Panda K, Sundaravel B, Dong CL, Tai NH, Lin IN. Structural and electrical properties of conducting diamond nanowires. ACS APPLIED MATERIALS & INTERFACES 2013; 5:1294-1301. [PMID: 23327783 DOI: 10.1021/am302430p] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Conducting diamond nanowires (DNWs) films have been synthesized by N₂-based microwave plasma enhanced chemical vapor deposition. The incorporation of nitrogen into DNWs films is examined by C 1s X-ray photoemission spectroscopy and morphology of DNWs is discerned using field-emission scanning electron microscopy and transmission electron microscopy (TEM). The electron diffraction pattern, the visible-Raman spectroscopy, and the near-edge X-ray absorption fine structure spectroscopy display the coexistence of sp³ diamond and sp² graphitic phases in DNWs films. In addition, the microstructure investigation, carried out by high-resolution TEM with Fourier transformed pattern, indicates diamond grains and graphitic grain boundaries on surface of DNWs. The same result is confirmed by scanning tunneling microscopy and scanning tunneling spectroscopy (STS). Furthermore, the STS spectra of current-voltage curves discover a high tunneling current at the position near the graphitic grain boundaries. These highly conducting regimes of grain boundaries form effective electron paths and its transport mechanism is explained by the three-dimensional (3D) Mott's variable range hopping in a wide temperature from 300 to 20 K. Interestingly, this specific feature of high conducting grain boundaries of DNWs demonstrates a high efficiency in field emission and pave a way to the next generation of high-definition flat panel displays or plasma devices.
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Sankaran KJ, Panda K, Sundaravel B, Chen HC, Lin IN, Lee CY, Tai NH. Engineering the interface characteristics of ultrananocrystalline diamond films grown on Au-coated Si substrates. ACS APPLIED MATERIALS & INTERFACES 2012; 4:4169-4176. [PMID: 22823911 DOI: 10.1021/am300894u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Enhanced electron field emission (EFE) properties have been observed for ultrananocrystalline diamond (UNCD) films grown on Au-coated Si (UNCD/Au-Si) substrates. The EFE properties of UNCD/Au-Si could be turned on at a low field of 8.9 V/μm, attaining EFE current density of 4.5 mA/cm(2) at an applied field of 10.5 V/μm, which is superior to that of UNCD films grown on Si (UNCD/Si) substrates with the same chemical vapor deposition process. Moreover, a significant difference in current-voltage curves from scanning tunneling spectroscopic measurements at the grain and the grain boundary has been observed. From the variation of normalized conductance (dI/dV)/(I/V) versus V, bandgap of UNCD/Au-Si is measured to be 2.8 eV at the grain and nearly metallic at the grain boundary. Current imaging tunneling spectroscopy measurements show that the grain boundaries have higher electron field emission capacity than the grains. The diffusion of Au into the interface layer that results in the induction of graphite and converts the metal-to-Si interface from Schottky to Ohmic contact is believed to be the authentic factors, resulting in marvelous EFE properties of UNCD/Au-Si.
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14
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Thomas JP, Chen HC, Tai NH, Lin IN. Freestanding ultrananocrystalline diamond films with homojunction insulating layer on conducting layer and their high electron field emission properties. ACS APPLIED MATERIALS & INTERFACES 2011; 3:4007-4013. [PMID: 21942707 DOI: 10.1021/am200867c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Freestanding ultrananocrystalline diamond (UNCD) films with homojunction insulating layer in situ grown on a conducting layer showed superior electron field emission (EFE) properties. The insulating layer of the films contains large dendrite type grains (400-600 nm in size), whereas the conducting layer contains nanosize equi-axed grains (5-20 nm in size) separated by grain boundaries of about 0.5-1 nm in width. The conducting layer possesses n-type (or semimetallic) conductivity of about 5.6 × 10(-3) (Ω cm)(-1), with sheet carrier concentration of about 1.4 × 10(12) cm(-2), which is ascribed to in situ doping of Li-species from LiNbO(3) substrates during growth of the films. The conducting layer intimately contacts the bottom electrodes (Cu-foil) by without forming the Schottky barrier, form homojunction with the insulating layer that facilitates injection of electrons into conduction band of diamond, and readily field emitted at low applied field. The EFE of freestanding UNCD films could be turned on at a low field of E(0) = 10.0 V/μm, attaining EFE current density of 0.2 mA/cm(2) at an applied field of 18.0 V/μm, which is superior to the EFE properties of UNCD films grown on Si substrates with the same chemical vapor deposition (CVD) process. Such an observation reveals the importance in the formation of homojunction on enhancing the EFE properties of materials. The large grain granular structure of the freestanding UNCD films is more robust against harsh environment and shows high potential toward diamond based electronic applications.
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Affiliation(s)
- Joseph P Thomas
- Department of Physics, Tamkang University, Tamsui 251, Taiwan, ROC.
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15
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Dementyev PS, Nizovtsev AS, Chesnokov EN. Infrared photoreaction of 2-chloroethyltrifluorosilane. J Photochem Photobiol A Chem 2011. [DOI: 10.1016/j.jphotochem.2011.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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16
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Itoh K. Diamond nanostructures: isotopes for nanoelectronic devices. NATURE NANOTECHNOLOGY 2009; 4:480-481. [PMID: 19662006 DOI: 10.1038/nnano.2009.214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Charge carriers have been confined by exploiting the small difference between the bandgap energies of the two naturally occurring stable isotopes of carbon.
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Affiliation(s)
- Kohei Itoh
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama, Japan.
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