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Feng J, Wagner SR, Zhang P. Interfacial Coupling and Electronic Structure of Two-Dimensional Silicon Grown on the Ag(111) Surface at High Temperature. Sci Rep 2015; 5:10310. [PMID: 26084916 PMCID: PMC5155519 DOI: 10.1038/srep10310] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 04/08/2015] [Indexed: 11/09/2022] Open
Abstract
Freestanding silicene, a monolayer of Si arranged in a honeycomb structure, has been predicted to give rise to massless Dirac fermions, akin to graphene. However, Si structures grown on a supporting substrate can show properties that strongly deviate from the freestanding case. Here, combining scanning tunneling microscopy/spectroscopy and differential conductance mapping, we show that the electrical properties of the (√3 x √3) phase of few-layer Si grown on Ag(111) strongly depend on film thickness, where the electron phase coherence length decreases and the free-electron-like surface state gradually diminishes when approaching the interface. These features are presumably attributable to the inelastic inter-band electron-electron scattering originating from the overlap between the surface state, interface state and the bulk state of the substrate. We further demonstrate that the intrinsic electronic structure of the as grown (√3 x √3) phase is identical to that of the (√3 x √3)R30° reconstructed Ag on Si(111), both of which exhibit the parabolic energy-momentum dispersion relation with comparable electron effective masses. These findings highlight the essential role of interfacial coupling on the properties of two-dimensional Si structures grown on supporting substrates, which should be thoroughly scrutinized in pursuit of silicene.
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Affiliation(s)
- Jiagui Feng
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-2320, USA
| | - Sean R Wagner
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-2320, USA
| | - Pengpeng Zhang
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-2320, USA
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2
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Chapman DA, Vorberger J, Fletcher LB, Baggott RA, Divol L, Döppner T, Falcone RW, Glenzer SH, Gregori G, Guymer TM, Kritcher AL, Landen OL, Ma T, Pak AE, Gericke DO. Observation of finite-wavelength screening in high-energy-density matter. Nat Commun 2015; 6:6839. [PMID: 25904218 PMCID: PMC4423234 DOI: 10.1038/ncomms7839] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 02/26/2015] [Indexed: 11/10/2022] Open
Abstract
A key component for the description of charged particle systems is the screening of the Coulomb interaction between charge carriers. First investigated in the 1920s by Debye and Hückel for electrolytes, charge screening is important for determining the structural and transport properties of matter as diverse as astrophysical and laboratory plasmas, nuclear matter such as quark-gluon plasmas, electrons in solids, planetary cores and charged macromolecules. For systems with negligible dynamics, screening is still mostly described using a Debye-Hückel-type approach. Here, we report the novel observation of a significant departure from the Debye-Hückel-type model in high-energy-density matter by probing laser-driven, shock-compressed plastic with high-energy X-rays. We use spectrally resolved X-ray scattering in a geometry that enables direct investigation of the screening cloud, and demonstrate that the observed elastic scattering amplitude is only well described within a more general approach.
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Affiliation(s)
- D. A. Chapman
- AWE plc, Radiation Physics Department, Aldermaston, Reading RG7 4PR, UK
- Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL, UK
| | - J. Vorberger
- Max-Planck-Institut für die Physik komplexer Systeme, Dresden 01187, Germany
| | - L. B. Fletcher
- High-Energy-Density Science Division, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - R. A. Baggott
- Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL, UK
| | - L. Divol
- National Ignition Facility and Photon Science Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - T. Döppner
- National Ignition Facility and Photon Science Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - R. W. Falcone
- Physics Department, University of California, Berkeley, California 94720, USA
| | - S. H. Glenzer
- High-Energy-Density Science Division, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - G. Gregori
- Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - T. M. Guymer
- AWE plc, Radiation Physics Department, Aldermaston, Reading RG7 4PR, UK
| | - A. L. Kritcher
- National Ignition Facility and Photon Science Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - O. L. Landen
- National Ignition Facility and Photon Science Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - T. Ma
- National Ignition Facility and Photon Science Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - A. E. Pak
- National Ignition Facility and Photon Science Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - D. O. Gericke
- Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry CV4 7AL, UK
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3
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Liang L, Wang J, Lin W, Sumpter BG, Meunier V, Pan M. Electronic bandgap and edge reconstruction in phosphorene materials. NANO LETTERS 2014; 14:6400-6. [PMID: 25343376 DOI: 10.1021/nl502892t] [Citation(s) in RCA: 210] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Single-layer black phosphorus (BP), or phosphorene, is a highly anisotropic two-dimensional elemental material possessing promising semiconductor properties for flexible electronics. However, the direct bandgap of single-layer black phosphorus predicted theoretically has not been directly measured, and the properties of its edges have not been considered in detail. Here we report atomic scale electronic variation related to strain-induced anisotropic deformation of the puckered honeycomb structure of freshly cleaved black phosphorus using a high-resolution scanning tunneling spectroscopy (STS) survey along the light (x) and heavy (y) effective mass directions. Through a combination of STS measurements and first-principles calculations, a model for edge reconstruction is also determined. The reconstruction is shown to self-passivate most dangling bonds by switching the coordination number of phosphorus from 3 to 5 or 3 to 4.
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Affiliation(s)
- Liangbo Liang
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
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4
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Yoshida Y, Yang HH, Huang HS, Guan SY, Yanagisawa S, Yokosuka T, Lin MT, Su WB, Chang CS, Hoffmann G, Hasegawa Y. Scanning tunneling microscopy/spectroscopy of picene thin films formed on Ag(111). J Chem Phys 2014; 141:114701. [DOI: 10.1063/1.4894439] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yasuo Yoshida
- The Institute of Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
| | - Hung-Hsiang Yang
- Department of Physics, National Taiwan University, Taipei 106, Taiwan
| | - Hsu-Sheng Huang
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Shu-You Guan
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Susumu Yanagisawa
- Department of Physics and Earth Science Department, University of the Ryukyus, 1 Nishihara, Okinawa 903-0213, Japan
| | - Takuya Yokosuka
- The Institute of Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
| | - Minn-Tsong Lin
- Department of Physics, National Taiwan University, Taipei 106, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Wei-Bin Su
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Chia-Seng Chang
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Germar Hoffmann
- The Institute of Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yukio Hasegawa
- The Institute of Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan
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5
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Theoretical investigation on nearsightedness of finite model and molecular systems based on linear response function analysis. Molecules 2014; 19:13358-73. [PMID: 25178060 PMCID: PMC6271732 DOI: 10.3390/molecules190913358] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 07/31/2014] [Accepted: 08/14/2014] [Indexed: 11/25/2022] Open
Abstract
We examined nearsightedness of electronic matter (NEM) of finite systems on the basis of linear response function (LRF). From the computational results of a square-well model system, the behavior of responses obviously depends on the number of electrons (N): as N increases, LRF, δρ(r)/δv(r′), decays rapidly for the distance, |r−r′|. This exemplifies that the principle suggested by Kohn and Prodan holds even for finite systems: the cause of NEM is destructive interference among electron density amplitudes. In addition, we examined double-well model systems, which have low-lying degenerate levels. In this case, there are two types of LRF: the cases of the half-filled and of full-filled in low-lying degenerate levels. The response for the former is delocalized, while that of the later is localized. These behaviors of model systems are discussed in relation to the molecular systems’ counterparts, H2, He22+, and He2 systems. We also see that NEM holds for the dissociated limit of H2, of which the mechanism is similar to that of the insulating state of solids as suggested by Kohn. We also examined LRF of alanine tripeptide system as well as butane and butadiene molecules, showing that NEM of the polypeptide system is caused by sp3 junctions at Cα atoms that prevent propagation of amplitudes of LRF, which is critically different from that of NEM for finite and infinite homogeneous systems.
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Kawai S, Canova FF, Glatzel T, Hynninen T, Meyer E, Foster AS. Measuring electric field induced subpicometer displacement of step edge ions. PHYSICAL REVIEW LETTERS 2012; 109:146101. [PMID: 23083258 DOI: 10.1103/physrevlett.109.146101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Indexed: 05/26/2023]
Abstract
We provide unambiguous evidence that the applied electrostatic field displaces step atoms of ionic crystal surfaces by subpicometers in different directions via the measurement of the lateral force interactions by bimodal dynamic force microscopy combined with multiscale theoretical simulations. Such a small imbalance in the electrostatic interaction of the shifted anion-cation ions leads to an extraordinary long-range feature potential variation and is now detectable with the extreme sensitivity of the bimodal detection.
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Affiliation(s)
- Shigeki Kawai
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
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7
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Wang W, Ji Y, Zhang H, Zhao A, Wang B, Yang J, Hou JG. Negative differential resistance in a hybrid silicon-molecular system: resonance between the intrinsic surface-states and the molecular orbital. ACS NANO 2012; 6:7066-7076. [PMID: 22793258 DOI: 10.1021/nn302107k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
It has been a long-term desire to fabricate hybrid silicon-molecular devices by taking advantages of organic molecules and the existing silicon-based technology. However, one of the challenging tasks is to design applicable functions on the basis of the intrinsic properties of the molecules, as well as the silicon substrates. Here we demonstrate a silicon-molecular system that produces negative differential resistance (NDR) by making use of the well-defined intrinsic surface-states of the Si (111)-√3 × √3-Ag (R3-Ag/Si) surface and the molecular orbital of cobalt(II)-phthalocyanine (CoPc) molecules. From our experimental results obtained using scanning tunneling microscopy/spectroscopy, we find that NDR robustly appears at the Co(2+) ion centers of the CoPc molecules, independent of the adsorption configuration of the CoPc molecules and irrespective of doping type and doping concentration of the silicon substrates. Joint with first principle calculations, we conclude that NDR is originated from the resonance between the intrinsic surface-state band S(1) of the R3-Ag/Si surface and the localized unoccupied Co(2+)d(z(2)) orbital of the adsorbed CoPc molecules. We expect that such a mechanism can be generally used in other silicon-molecular systems.
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Affiliation(s)
- Weihua Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China
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8
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Teichmann K, Wenderoth M, Loth S, Garleff JK, Wijnheijmer AP, Koenraad PM, Ulbrich RG. Bistable charge configuration of donor systems near the GaAs(110) surfaces. NANO LETTERS 2011; 11:3538-3542. [PMID: 21842882 DOI: 10.1021/nl201024b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In gated semiconductor devices, the space charge layer that is located under the gate electrode acts as the functional element. With increasing gate voltage, the microscopic process forming this space charge layer involves the subsequent ionization or electron capture of individual dopants within the semiconductor. In this Letter, a scanning tunneling microscope tip is used as a movable gate above the (110) surface of n-doped GaAs. We study the build-up process of the space charge region considering donors and visualize the charge states of individual and multi donor systems. The charge configuration of single donors is determined by the position of the tip and the applied gate voltage. In contrast, a two donor system with interdonor distances smaller than 10 nm shows a more complex behavior. The electrostatic interaction between the donors in combination with the modification of their electronic properties close to the surface results in ionization gaps and bistable charge switching behavior.
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Affiliation(s)
- K Teichmann
- IV. Physikalisches Institut, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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9
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Niimi Y, Kambara H, Fukuyama H. Localized distributions of quasi-two-dimensional electronic states near defects artificially created at graphite surfaces in magnetic fields. PHYSICAL REVIEW LETTERS 2009; 102:026803. [PMID: 19257303 DOI: 10.1103/physrevlett.102.026803] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Indexed: 05/27/2023]
Abstract
We measured the local density of states of a quasi two-dimensional electron system (2DES) near defects, artificially created by Ar-ion sputtering, on surfaces of highly oriented pyrolytic graphite (HOPG) with scanning tunneling spectroscopy (STS) in high magnetic fields. At valley energies of the Landau level spectrum, we found two typical localized distributions of the 2DES depending on the defects. These are new types of distributions which are not observed in the previous STS work at the HOPG surface near a point defect [Y. Niimi, Phys. Rev. Lett. 97, 236804 (2006).10.1103/PhysRevLett.97.236804]. With increasing energy, we observed gradual transformation from the localized distributions to the extended ones as expected for the integer quantum Hall state. We show that the defect potential depth is responsible for the two localized distributions from comparison with theoretical calculations.
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Affiliation(s)
- Y Niimi
- Department of Physics, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan
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10
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Li Q, Yamazaki S, Eguchi T, Hasegawa Y, Kim H, Kahng SJ, Feng Jia J, Xue QK. Adsorption, manipulation and self-assembling of TBrPP-Co molecules on a Ag/Si(111) surface by scanning tunnelling microscopy. NANOTECHNOLOGY 2008; 19:465707. [PMID: 21836262 DOI: 10.1088/0957-4484/19/46/465707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Individual adsorption and two-dimensional assembling of 5,10,15,20-tetrakis-(4-bromophenyl)-porphyrin-Co (TBrPP-Co) molecules on a Si(111)-[Formula: see text] Ag reconstructed surface have been studied using low-temperature scanning tunnelling microscopy (STM). All the isolated molecules are observed in a planar shape with slight distortion. The isolated molecules can be controllably rotated with an STM tip to the orientation along the trigonal lattice ([Formula: see text] direction) of the substrate. With an increased coverage (0.07 ML) and appropriate annealing, the molecules assemble to form three types of ordered phase. The long-range ordered structures, however, disappear at higher coverage (0.75 ML).
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Affiliation(s)
- Qing Li
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5, Kashiwa-no-ha, Kashiwa 277-8581, Japan. Institute of Physics, Chinese Academy of Science, Beijing 100080, People's Republic of China
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11
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Yao YX, Liu X, Fu Q, Li WX, Tan DL, Bao XH. Unique Reactivity of Confined Metal Atoms on a Silicon Substrate. Chemphyschem 2008; 9:975-9. [DOI: 10.1002/cphc.200700840] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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An T, Nishio T, Eguchi T, Ono M, Nomura A, Akiyama K, Hasegawa Y. Atomically resolved imaging by low-temperature frequency-modulation atomic force microscopy using a quartz length-extension resonator. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:033703. [PMID: 18377011 DOI: 10.1063/1.2830937] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Low-temperature ultrahigh vacuum frequency-modulation atomic force microscopy (AFM) was performed using a 1 MHz length-extension type of quartz resonator as a force sensor. Taking advantage of the high stiffness of the resonator, the AFM was operated with an oscillation amplitude smaller than 100 pm, which is favorable for high spatial resolution, without snapping an AFM tip onto a sample surface. Atomically resolved imaging of the adatom structure on the Si(111)-(7x7) surface was successfully obtained.
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Affiliation(s)
- Toshu An
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa 277-8581, Japan
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13
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Matsuda I, Liu C, Hirahara T, Ueno M, Tanikawa T, Kanagawa T, Hobara R, Yamazaki S, Hasegawa S, Kobayashi K. Electron-phonon interaction and localization of surface-state carriers in a metallic monolayer. PHYSICAL REVIEW LETTERS 2007; 99:146805. [PMID: 17930700 DOI: 10.1103/physrevlett.99.146805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Indexed: 05/25/2023]
Abstract
Temperature-dependent electron transport in a metallic surface superstructure, Si(111)sqrt[3] x sqrt[3]-Ag, was studied by a micro-four-point probe method and photoemission spectroscopy. The surface-state conductivity exhibits a sharp transition from metallic conduction to strong localization at approximately 150 K. The metallic regime is due to electron-phonon interaction while the localization seemingly originates from coherency of electron waves. Random potential variations, caused by Friedel oscillations of surface electrons around defects, likely induce strong carrier localization.
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Affiliation(s)
- Iwao Matsuda
- Department of Physics, School of Science, The University of Tokyo, 7-3-1 Hongo, Tokyo, Japan.
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Varchon F, Feng R, Hass J, Li X, Nguyen BN, Naud C, Mallet P, Veuillen JY, Berger C, Conrad EH, Magaud L. Electronic structure of epitaxial graphene layers on SiC: effect of the substrate. PHYSICAL REVIEW LETTERS 2007. [PMID: 17930540 DOI: 10.1103/physrevb.76.041403] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
A strong substrate-graphite bond is found in the first all-carbon layer by density functional theory calculations and x-ray diffraction for few graphene layers grown epitaxially on SiC. This first layer is devoid of graphene electronic properties and acts as a buffer layer. The graphene nature of the film is recovered by the second carbon layer grown on both the (0001) and (0001[over]) 4H-SiC surfaces. We also present evidence of a charge transfer that depends on the interface geometry. Hence the graphene is doped and a gap opens at the Dirac point after three Bernal stacked carbon layers are formed.
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Affiliation(s)
- F Varchon
- Institut Néel, CNRS-UJF, BP 166, 38042 Grenoble Cedex 9, France
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Kanazawa K, Sainoo Y, Konishi Y, Yoshida S, Taninaka A, Okada A, Berthe M, Kobayashi N, Takeuchi O, Shigekawa H. Anisotropic Free-Electron-Like Dispersions and Standing Waves Realized in Self-Assembled Monolayers of Glycine on Cu(100). J Am Chem Soc 2007; 129:740-1. [PMID: 17243792 DOI: 10.1021/ja066318u] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ken Kanazawa
- Institute of Applied Physics, CREST-JST, 21st Century COE, University of Tsukuba, Tsukuba 305-8573, Japan
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