1
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Pitters J, Croshaw J, Achal R, Livadaru L, Ng S, Lupoiu R, Chutora T, Huff T, Walus K, Wolkow RA. Atomically Precise Manufacturing of Silicon Electronics. ACS NANO 2024; 18:6766-6816. [PMID: 38376086 PMCID: PMC10919096 DOI: 10.1021/acsnano.3c10412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 02/01/2024] [Accepted: 02/06/2024] [Indexed: 02/21/2024]
Abstract
Atomically precise manufacturing (APM) is a key technique that involves the direct control of atoms in order to manufacture products or components of products. It has been developed most successfully using scanning probe methods and has received particular attention for developing atom scale electronics with a focus on silicon-based systems. This review captures the development of silicon atom-based electronics and is divided into several sections that will cover characterization and atom manipulation of silicon surfaces with scanning tunneling microscopy and atomic force microscopy, development of silicon dangling bonds as atomic quantum dots, creation of atom scale devices, and the wiring and packaging of those circuits. The review will also cover the advance of silicon dangling bond logic design and the progress of silicon quantum atomic designer (SiQAD) simulators. Finally, an outlook of APM and silicon atom electronics will be provided.
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Affiliation(s)
- Jason Pitters
- Nanotechnology
Research Centre, National Research Council
of Canada, Edmonton, Alberta T6G 2M9, Canada
| | - Jeremiah Croshaw
- Department
of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - Roshan Achal
- Department
of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
- Quantum
Silicon Inc., Edmonton, Alberta T6G 2M9, Canada
| | - Lucian Livadaru
- Department
of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
- Quantum
Silicon Inc., Edmonton, Alberta T6G 2M9, Canada
| | - Samuel Ng
- Department
of Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Robert Lupoiu
- School
of Engineering, Stanford University, Stanford, California 94305, United States
| | - Taras Chutora
- Department
of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - Taleana Huff
- Canadian
Bank Note Company, Ottawa, Ontario K1Z 1A1, Canada
| | - Konrad Walus
- Department
of Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Robert A. Wolkow
- Department
of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
- Quantum
Silicon Inc., Edmonton, Alberta T6G 2M9, Canada
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2
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Pavlova TV, Shevlyuga VM. Enhancing the reactivity of Si(100)-Cl toward PBr3 by charging Si dangling bonds. J Chem Phys 2023; 159:214701. [PMID: 38038208 DOI: 10.1063/5.0178757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 11/08/2023] [Indexed: 12/02/2023] Open
Abstract
The interaction of the PBr3 molecule with Si dangling bonds (DBs) on a chlorinated Si(100) surface was studied. The DBs were charged in a scanning tunneling microscope (STM) and then exposed to PBr3 directly in the STM chamber. Uncharged DBs rarely react with molecules. On the contrary, almost all positively charged DBs were filled with molecule fragments. As a result of the PBr3 interaction with the positively charged DB, the molecule dissociated into PBr2 and Br with the formation of a Si-Br bond and PBr2 desorption. These findings show that charged DBs significantly modify the reactivity of the surface toward PBr3. Additionally, we calculated PH3 adsorption on a Si(100)-2 × 1-H surface with DBs and found that the DB charge also has a significant impact. As a result, we demonstrated that the positively charged DB with a doubly unoccupied state enhances the adsorption of molecules with a lone pair of electrons.
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Affiliation(s)
- T V Pavlova
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov str. 38, 119991 Moscow, Russia
- HSE University, Myasnitskaya str. 20, 101000 Moscow, Russia
| | - V M Shevlyuga
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov str. 38, 119991 Moscow, Russia
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3
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Tseng LT, Karadan P, Kazazis D, Constantinou PC, Stock TJ, Curson NJ, Schofield SR, Muntwiler M, Aeppli G, Ekinci Y. Resistless EUV lithography: Photon-induced oxide patterning on silicon. SCIENCE ADVANCES 2023; 9:eadf5997. [PMID: 37075116 PMCID: PMC10115406 DOI: 10.1126/sciadv.adf5997] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In this work, we show the feasibility of extreme ultraviolet (EUV) patterning on an HF-treated silicon (100) surface in the absence of a photoresist. EUV lithography is the leading lithography technique in semiconductor manufacturing due to its high resolution and throughput, but future progress in resolution can be hampered because of the inherent limitations of the resists. We show that EUV photons can induce surface reactions on a partially hydrogen-terminated silicon surface and assist the growth of an oxide layer, which serves as an etch mask. This mechanism is different from the hydrogen desorption in scanning tunneling microscopy-based lithography. We achieve silicon dioxide/silicon gratings with 75-nanometer half-pitch and 31-nanometer height, demonstrating the efficacy of the method and the feasibility of patterning with EUV lithography without the use of a photoresist. Further development of the resistless EUV lithography method can be a viable approach to nanometer-scale lithography by overcoming the inherent resolution and roughness limitations of photoresist materials.
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Affiliation(s)
- Li-Ting Tseng
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | | | - Dimitrios Kazazis
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
- Corresponding author.
| | | | - Taylor J. Z. Stock
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, UK
| | - Neil J. Curson
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, UK
| | - Steven R. Schofield
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
- Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | | | - Gabriel Aeppli
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
- Laboratory for Solid State Physics and Quantum Center, ETH-Zürich, 8093 Zürich, Switzerland
- Institut de Physique, EPFL, 1015 Lausanne, Switzerland
| | - Yasin Ekinci
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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4
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Precise atom manipulation through deep reinforcement learning. Nat Commun 2022; 13:7499. [PMID: 36470857 PMCID: PMC9722711 DOI: 10.1038/s41467-022-35149-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 11/18/2022] [Indexed: 12/12/2022] Open
Abstract
Atomic-scale manipulation in scanning tunneling microscopy has enabled the creation of quantum states of matter based on artificial structures and extreme miniaturization of computational circuitry based on individual atoms. The ability to autonomously arrange atomic structures with precision will enable the scaling up of nanoscale fabrication and expand the range of artificial structures hosting exotic quantum states. However, the a priori unknown manipulation parameters, the possibility of spontaneous tip apex changes, and the difficulty of modeling tip-atom interactions make it challenging to select manipulation parameters that can achieve atomic precision throughout extended operations. Here we use deep reinforcement learning (DRL) to control the real-world atom manipulation process. Several state-of-the-art reinforcement learning (RL) techniques are used jointly to boost data efficiency. The DRL agent learns to manipulate Ag adatoms on Ag(111) surfaces with optimal precision and is integrated with path planning algorithms to complete an autonomous atomic assembly system. The results demonstrate that state-of-the-art DRL can offer effective solutions to real-world challenges in nanofabrication and powerful approaches to increasingly complex scientific experiments at the atomic scale.
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5
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Yang D, Mannan A, Murakami F, Tonouchi M. Rapid, noncontact, sensitive, and semiquantitative characterization of buffered hydrogen-fluoride-treated silicon wafer surfaces by terahertz emission spectroscopy. LIGHT, SCIENCE & APPLICATIONS 2022; 11:334. [PMID: 36433935 PMCID: PMC9700743 DOI: 10.1038/s41377-022-01033-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 10/25/2022] [Accepted: 11/06/2022] [Indexed: 06/16/2023]
Abstract
Advances in modern semiconductor integrated circuits have always demanded faster and more sensitive analytical methods on a large-scale wafer. The surface of wafers is fundamentally essential to start building circuits, and quantitative measures of the surface potential, defects, contamination, passivation quality, and uniformity are subject to inspection. The present study provides a new approach to access those by means of terahertz (THz) emission spectroscopy. Upon femtosecond laser illumination, THz radiation, which is sensitive to the surface electric fields of the wafer, is generated. Here, we systematically research the THz emission properties of silicon surfaces under different surface conditions, such as the initial surface with a native oxide layer, a fluorine-terminated surface, and a hydrogen-terminated surface. Meanwhile, a strong doping concentration dependence of the THz emission amplitude from the silicon surface has been revealed in different surface conditions, which implies a semiquantitative connection between the THz emission and the surface band bending with the surface dipoles. Laser-induced THz emission spectroscopy is a promising method for evaluating local surface properties on a wafer scale.
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Affiliation(s)
- Dongxun Yang
- Institute of Laser Engineering, Osaka University 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Abdul Mannan
- Institute of Laser Engineering, Osaka University 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Fumikazu Murakami
- Institute of Laser Engineering, Osaka University 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Masayoshi Tonouchi
- Institute of Laser Engineering, Osaka University 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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6
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Pavlova TV, Shevlyuga V. Vacancy diffusion on a brominated Si(100) surface: Critical effect of the dangling bond charge state. J Chem Phys 2022; 157:124705. [DOI: 10.1063/5.0102546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Silicon dangling bonds (DBs) on an adsorbate-covered Si(100) surface can be created in a scanning tunneling microscope (STM) with high precision required for a number of applications. However, vacancies containing DBs can diffuse, disrupting precisely created structures. In this work, we study the diffusion of Br vacancies on a Si(100)-2x1-Br surface in an STM under typical imaging conditions. In agreement with previous work, Br vacancies diffuse at a positive sample bias voltage. Here, we demonstrated that only vacancies containing a positively charged DB hop across the two atoms of a single Si dimer, while vacancies containing neutral and negatively charged DBs do not. Calculations based on the density functional theory confirmed that positively charged Br (and Cl) vacancies have a minimum activation barrier. We propose that diffusion operates by both one-electron and two-electron mechanisms depending on the applied voltage. Our results show that the DB charge has a critical effect on the vacancy diffusion. This effect should be taken into account when imaging surface structures with charged DBs, as well as when studying the diffusion of other atoms and molecules on the Si(100) surface with vacancies in an adsorbate layer.
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Affiliation(s)
| | - Vladimir Shevlyuga
- Institute of General Physics named after A P Prokhorov Russian Academy of Sciences, Russia
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7
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Osiecki JR, Suto S, Chutia A. Periodic corner holes on the Si(111)-7×7 surface can trap silver atoms. Nat Commun 2022; 13:2973. [PMID: 35624114 PMCID: PMC9142567 DOI: 10.1038/s41467-022-29768-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 03/29/2022] [Indexed: 11/09/2022] Open
Abstract
Advancement in nanotechnology to a large extent depends on the ability to manipulate materials at the atomistic level, including positioning single atoms on the active sites of the surfaces of interest, promoting strong chemical bonding. Here, we report a long-time confinement of a single Ag atom inside a corner hole (CH) of the technologically relevant Si(111)-7×7 surface, which has comparable size as a fullerene C60 molecule with a single dangling bond at the bottom center. Experiments reveal that a set of 17 Ag atoms stays entrapped in the CH for the entire duration of experiment, 4 days and 7 h. Warming up the surface to about 150 °C degrees forces the Ag atoms out of the CH within a few minutes. The processes of entrapment and diffusion are temperature dependent. Theoretical calculations based on density functional theory support the experimental results confirming the highest adsorption energy at the CH for the Ag atom, and suggest that other elements such as Li, Na, Cu, Au, F and I may display similar behavior. The capability of atomic manipulation at room temperature makes this effect particularly attractive for building single atom devices and possibly developing new engineering and nano-manufacturing methods. Positioning and trapping single atoms at specific sites of surfaces is a challenging goal that can advance the development of single atom devices. Here the authors demonstrate that single Ag atoms are trapped inside corner holes of the Si(111)-7×7 surface for more than 4 days at room temperature, and suggest that this behavior may be shared by other elements.
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Affiliation(s)
- Jacek R Osiecki
- MAX IV Laboratory, Lund University, SE22100, Lund, Sweden. .,Department of Physics, Tohoku University, Sendai, 980-8578, Japan.
| | - Shozo Suto
- Department of Physics, Tohoku University, Sendai, 980-8578, Japan.
| | - Arunabhiram Chutia
- School of Chemistry, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, United Kingdom.
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8
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Jolie W, Hung TC, Niggli L, Verlhac B, Hauptmann N, Wegner D, Khajetoorians AA. Creating Tunable Quantum Corrals on a Rashba Surface Alloy. ACS NANO 2022; 16:4876-4883. [PMID: 35271251 PMCID: PMC8945344 DOI: 10.1021/acsnano.2c00467] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 03/08/2022] [Indexed: 06/10/2023]
Abstract
Artificial lattices derived from assembled atoms on a surface using scanning tunneling microscopy present a platform to create matter with tailored electronic, magnetic, and topological properties. However, artificial lattice studies to date have focused exclusively on surfaces with weak spin-orbit coupling. Here, we illustrate the creation and characterization of quantum corrals from iron atoms on the prototypical Rashba surface alloy BiCu2, using low-temperature scanning tunneling microscopy and spectroscopy. We observe very complex interference patterns that result from the interplay of the size of the confinement potential, the intricate multiband scattering, and hexagonal warping from the underlying band structure. On the basis of a particle-in-a-box model that accounts for the observed multiband scattering, we qualitatively link the resultant confined wave functions with the contributions of the various scattering channels. On the basis of these results, we studied the coupling of two quantum corrals and the effect of the underlying warping toward the creation of artificial dimer states. This platform may provide a perspective toward the creation of correlated artificial lattices with nontrivial topology.
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9
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Onoda J, Khademi A, Wolkow RA, Pitters J. Ohmic Contact to Two-Dimensional Nanofabricated Silicon Structures with a Two-Probe Scanning Tunneling Microscope. ACS NANO 2021; 15:19377-19386. [PMID: 34780687 DOI: 10.1021/acsnano.1c05777] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We used multiprobe scanning tunneling microscope (STM) to fabricate and electrically characterize nanostructures on Si surfaces. We overcame resistive contacts by using field evaporation to clean tip apexes in order to create Ohmic contact with the Si surface states on a Si substrate. A two-probe (2P-) STM with Ohmic contact allowed for measurement at very low bias, limiting conduction through space-charge layer and bulk states. The Ohmic 2P-STM measurement clarified the surface conductivity of the Si(111)-(7 × 7) surface. We also confirmed that Ohmic 2P-STM can be replaced with more convenient Ohmic one-probe STM for the conductance measurements on the Si surface. We prepared nanostructures using STM lithography to define electronically isolated two-dimensional (2D) regions with various aspect ratios. Their surface conduction properties are described well by the conventional sheet model, proving the diffusive 2D conduction on the Si surface. Constrictions and breaks in 2D structures were also evaluated. Ohmic 2P-STM will be helpful for the investigation of exploratory atomic-scale circuitry or cutting-edge materials sciences.
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Affiliation(s)
- Jo Onoda
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
| | - Ali Khademi
- Metrology Research Centre, National Research Council of Canada, 1200 Montreal Road, Ottawa, Ontario K1A 0R6, Canada
| | - Robert A Wolkow
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
- Quantum Silicon, Inc., Edmonton Alberta T6G 2M9, Canada
| | - Jason Pitters
- Nanotechnology Research Centre, National Research Council Canada, Edmonton, Alberta T6G 2M9, Canada
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10
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Owen JHG, Campbell Q, Santini R, Ivie JA, Baczewski AD, Schmucker SW, Bussmann E, Misra S, Randall JN. Al-alkyls as acceptor dopant precursors for atomic-scale devices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:464001. [PMID: 34399418 DOI: 10.1088/1361-648x/ac1ddf] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
Atomically precise ultradoping of silicon is possible with atomic resists, area-selective surface chemistry, and a limited set of hydride and halide precursor molecules, in a process known as atomic precision advanced manufacturing (APAM). It is desirable to expand this set of precursors to include dopants with organic functional groups and here we consider aluminium alkyls, to expand the applicability of APAM. We explore the impurity content and selectivity that results from using trimethyl aluminium and triethyl aluminium precursors on Si(001) to ultradope with aluminium through a hydrogen mask. Comparison of the methylated and ethylated precursors helps us understand the impact of hydrocarbon ligand selection on incorporation surface chemistry. Combining scanning tunneling microscopy and density functional theory calculations, we assess the limitations of both classes of precursor and extract general principles relevant to each.
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Affiliation(s)
- J H G Owen
- Zyvex Labs, Richardson, TX, United States of America
| | - Q Campbell
- Sandia National Labs, Albuquerque, NM, United States of America
| | - R Santini
- Zyvex Labs, Richardson, TX, United States of America
| | - J A Ivie
- Sandia National Labs, Albuquerque, NM, United States of America
| | - A D Baczewski
- Sandia National Labs, Albuquerque, NM, United States of America
| | - S W Schmucker
- Sandia National Labs, Albuquerque, NM, United States of America
| | - E Bussmann
- Sandia National Labs, Albuquerque, NM, United States of America
| | - S Misra
- Sandia National Labs, Albuquerque, NM, United States of America
| | - J N Randall
- Zyvex Labs, Richardson, TX, United States of America
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11
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Adamkiewicz A, Bohamud T, Reutzel M, Höfer U, Dürr M. Tip-induced β-hydrogen dissociation in an alkyl group bound on Si(001). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:344004. [PMID: 34111848 DOI: 10.1088/1361-648x/ac0a1c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 06/10/2021] [Indexed: 06/12/2023]
Abstract
Atomic-scale chemical modification of surface-adsorbed ethyl groups on Si(001) was induced and studied by means of scanning tunneling microscopy. Tunneling at sample bias >+1.5 V leads to tip-induced C-H cleavage of aβ-hydrogen of the covalently bound ethyl configuration. The reaction is characterized by the formation of an additional Si-H and a Si-C bond. The reaction probability shows a linear dependence on the tunneling current at 300 K; the reaction is largely suppressed at 50 K. The observed tip-induced surface reaction at room temperature is thus attributed to a one-electron excitation in combination with thermal activation.
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Affiliation(s)
- A Adamkiewicz
- Fachbereich Physik and Zentrum für Materialwissenschaften, Philipps-Universität Marburg, D-35032 Marburg, Germany
| | - T Bohamud
- Fachbereich Physik and Zentrum für Materialwissenschaften, Philipps-Universität Marburg, D-35032 Marburg, Germany
| | - M Reutzel
- Fachbereich Physik and Zentrum für Materialwissenschaften, Philipps-Universität Marburg, D-35032 Marburg, Germany
- I. Physikalisches Institut, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - U Höfer
- Fachbereich Physik and Zentrum für Materialwissenschaften, Philipps-Universität Marburg, D-35032 Marburg, Germany
| | - M Dürr
- Fachbereich Physik and Zentrum für Materialwissenschaften, Philipps-Universität Marburg, D-35032 Marburg, Germany
- Institut für Angewandte Physik and Zentrum für Materialforschung, Justus-Liebig-Universität Giessen, D-35392 Giessen, Germany
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12
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Mueller SM, Kim D, McMillan SR, Tjung SJ, Repicky JJ, Gant S, Lang E, Bergmann F, Werner K, Chowdhury E, Asthagiri A, Flatté ME, Gupta JA. Tunable tunnel barriers in a semiconductor via ionization of individual atoms. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:275002. [PMID: 33878736 DOI: 10.1088/1361-648x/abf9bd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 04/20/2021] [Indexed: 06/12/2023]
Abstract
We report scanning tunneling microscopy (STM) studies of individual adatoms deposited on an InSb(110) surface. The adatoms can be reproducibly dropped off from the STM tip by voltage pulses, and impact tunneling into the surface by up to ∼100×. The spatial extent and magnitude of the tunneling effect are widely tunable by imaging conditions such as bias voltage, set current and photoillumination. We attribute the effect to occupation of a (+/0) charge transition level, and switching of the associated adatom-induced band bending. The effect in STM topographic images is well reproduced by transport modeling of filling and emptying rates as a function of the tip position. STM atomic contrast and tunneling spectra are in good agreement with density functional theory calculations for In adatoms. The adatom ionization effect can extend to distances greater than 50 nm away, which we attribute to the low concentration and low binding energy of the residual donors in the undoped InSb crystal. These studies demonstrate how individual atoms can be used to sensitively control current flow in nanoscale devices.
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Affiliation(s)
- Sara M Mueller
- Department of Physics, Ohio State University, Columbus, OH 43210, United States of America
| | - Dongjoon Kim
- Department of Chemical and Biomolecular Engineering, Ohio State University, Columbus, OH 43210, United States of America
| | - Stephen R McMillan
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, United States of America
| | - Steven J Tjung
- Department of Physics, Ohio State University, Columbus, OH 43210, United States of America
| | - Jacob J Repicky
- Department of Physics, Ohio State University, Columbus, OH 43210, United States of America
| | - Stephen Gant
- Department of Physics, Ohio State University, Columbus, OH 43210, United States of America
| | - Evan Lang
- Department of Physics, Ohio State University, Columbus, OH 43210, United States of America
| | - Fedor Bergmann
- Bergmann Messgeraete Entwicklung KG, Kocheler Strasse 101, 82418 Murnau, Germany
| | - Kevin Werner
- Department of Physics, Ohio State University, Columbus, OH 43210, United States of America
- BAE Systems, 130 Daniel Webster Hwy., MER15-1813, Merrimack, NH 03054, United States of America
| | - Enam Chowdhury
- Department of Physics, Ohio State University, Columbus, OH 43210, United States of America
- Department of Material Science and Engineering, Ohio State University, Columbus OH 43210, United States of America
| | - Aravind Asthagiri
- Department of Chemical and Biomolecular Engineering, Ohio State University, Columbus, OH 43210, United States of America
| | - Michael E Flatté
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, United States of America
| | - Jay A Gupta
- Department of Physics, Ohio State University, Columbus, OH 43210, United States of America
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13
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Croshaw J, Huff T, Rashidi M, Wood J, Lloyd E, Pitters J, Wolkow RA. Ionic charge distributions in silicon atomic surface wires. NANOSCALE 2021; 13:3237-3245. [PMID: 33533379 DOI: 10.1039/d0nr08295c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Using a non-contact atomic force microscope (nc-AFM), we examine continuous dangling bond (DB) wire structures patterned on the hydrogen terminated silicon (100)-2 × 1 surface. By probing the DB structures at varying energies, we identify the formation of previously unobserved ionic charge distributions which are correlated to the net charge of DB wires and their predicted degrees of freedom in lattice distortions. Performing spectroscopic analysis, we identify higher energy configurations corresponding to alternative lattice distortions as well as tip-induced charging effects. By varying the length and orientation of these DB structures, we further highlight key features in the formation of these ionic surface phases.
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Affiliation(s)
- Jeremiah Croshaw
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada. and Quantum Silicon Inc., Edmonton, Alberta T6G 2M9, Canada
| | - Taleana Huff
- Nanotechnology Research Centre, National Research Council Canada, Edmonton, Alberta T6G 2M9, Canada
| | - Mohammad Rashidi
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada.
| | - John Wood
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada.
| | - Erika Lloyd
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada.
| | - Jason Pitters
- Nanotechnology Research Centre, National Research Council Canada, Edmonton, Alberta T6G 2M9, Canada
| | - Robert A Wolkow
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada. and Quantum Silicon Inc., Edmonton, Alberta T6G 2M9, Canada and Nanotechnology Research Centre, National Research Council Canada, Edmonton, Alberta T6G 2M9, Canada
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14
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Xu G, Zhou T, Scharf B, Žutić I. Optically Probing Tunable Band Topology in Atomic Monolayers. PHYSICAL REVIEW LETTERS 2020; 125:157402. [PMID: 33095598 DOI: 10.1103/physrevlett.125.157402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 06/26/2020] [Accepted: 09/03/2020] [Indexed: 06/11/2023]
Abstract
In many atomically thin materials, their optical absorption is dominated by excitonic transitions. It was recently found that optical selection rules in these materials are influenced by the band topology near the valleys. We propose that gate-controlled band ordering in a single atomic monolayer, through changes in the valley winding number and excitonic transitions, can be probed in helicity-resolved absorption and photoluminescence. This predicted tunable band topology is confirmed by combining an effective Hamiltonian and a Bethe-Salpeter equation for an accurate description of excitons, with first-principles calculations suggesting its realization in Sb-based monolayers.
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Affiliation(s)
- Gaofeng Xu
- Department of Physics, University at Buffalo, State University of New York, Buffalo, New York 14260, USA
| | - Tong Zhou
- Department of Physics, University at Buffalo, State University of New York, Buffalo, New York 14260, USA
| | - Benedikt Scharf
- Institute for Theoretical Physics and Astrophysics and Würzburg-Dresden Cluster of Excellence ct.qmat, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Igor Žutić
- Department of Physics, University at Buffalo, State University of New York, Buffalo, New York 14260, USA
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15
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Pavlova TV. Hydrogen inserted into the Si(100)-2 × 1-H surface: a first-principles study. Phys Chem Chem Phys 2020; 22:21851-21857. [PMID: 32966437 DOI: 10.1039/d0cp03691a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hydrogen can be inserted into Si(100)-2 × 1-H during surface preparation or during the hydrogen desorption lithography used to create atomic-scale devices. Here, a hydrogen atom inserted into a hydrogen monolayer on the Si(100)-2 × 1 surface has been studied using density functional theory. Hydrogen-induced defects were considered in their neutral, negative, and positive charge states. It was found that hydrogen forms a dihydride unit on the surface in the most stable neutral and negative charge states. Hydrogen located in the groove between dimer rows is also one of the most stable negative charge states. In the positive charge state, hydrogen forms a three-center bond inside a Si dimer, Si-H-Si, similar to the bulk case. A comparison of simulated scanning tunneling microscopy (STM) images with the experimental data available in the literature showed that neutral and negatively charged hydrogen-induced defects were already observed in experiments. The results reveal that the H atom inserted into a hydrogen monolayer on the Si(100)-2 × 1 surface can lead to the formation of a positively or negatively charged defect. It is shown that H atoms in the considered configurations can play a role in various surface reactions.
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Affiliation(s)
- Tatiana V Pavlova
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, Russia. and National Research University Higher School of Economics, Moscow, Russia
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16
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Croshaw J, Dienel T, Huff T, Wolkow R. Atomic defect classification of the H-Si(100) surface through multi-mode scanning probe microscopy. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:1346-1360. [PMID: 32974113 PMCID: PMC7492692 DOI: 10.3762/bjnano.11.119] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 08/11/2020] [Indexed: 06/11/2023]
Abstract
The combination of scanning tunnelling microscopy (STM) and non-contact atomic force microscopy (nc-AFM) allows enhanced extraction and correlation of properties not readily available via a single imaging mode. We demonstrate this through the characterization and classification of several commonly found defects of the hydrogen-terminated silicon (100)-2 × 1 surface (H-Si(100)-2 × 1) by using six unique imaging modes. The H-Si surface was chosen as it provides a promising platform for the development of atom scale devices, with recent work showing their creation through precise desorption or placement of surface hydrogen atoms. While samples with relatively large areas of the H-Si surface are routinely created using an in situ methodology, surface defects are inevitably formed reducing the area available for patterning. By probing the surface using the different interactivity afforded by either hydrogen- or silicon-terminated tips, we are able to extract new insights regarding the atomic and electronic structure of these defects. This allows for the confirmation of literature assignments of several commonly found defects, as well as proposed classifications of previously unreported and unassigned defects. By combining insights from multiple imaging modes, better understanding of their successes and shortcomings in identifying defect structures and origins is achieved. With this, we take the first steps toward enabling the creation of superior H-Si surfaces through an improved understanding of surface defects, ultimately leading to more consistent and reliable fabrication of atom scale devices.
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Affiliation(s)
- Jeremiah Croshaw
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada
- Quantum Silicon, Inc., Edmonton, Alberta, T6G 2M9, Canada
| | - Thomas Dienel
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada
- Department of Materials Science and Engineering, Cornell University, Ithaca NY 14853, USA
| | - Taleana Huff
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada
- Nanotechnology Research Centre, National Research Council Canada, Edmonton, Alberta, T6G 2M9, Canada
| | - Robert Wolkow
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada
- Quantum Silicon, Inc., Edmonton, Alberta, T6G 2M9, Canada
- Nanotechnology Research Centre, National Research Council Canada, Edmonton, Alberta, T6G 2M9, Canada
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17
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Pohlman AJ, Kaliakin DS, Varganov SA, Casey SM. Spin controlled surface chemistry: alkyl desorption from Si(100)-2×1 by nonadiabatic hydrogen elimination. Phys Chem Chem Phys 2020; 22:16641-16647. [PMID: 32661543 DOI: 10.1039/d0cp01913e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An understanding of the role that spin states play in semiconductor surface chemical reactions is currently limited. Herein, we provide evidence of a nonadiabatic reaction involving a localized singlet to triplet thermal excitation of the Si(100) surface dimer dangling bond. By comparing the β-hydrogen elimination kinetics of ethyl adsorbates probed by thermal desorption experiments to electronic structure calculation results, we determined that a coverage-dependent change in mechanism occurs. At low coverage, a nonadiabatic, inter-dimer mechanism is dominant, while adiabatic mechanisms become dominant at higher coverage. Computational results indicate that the spin crossover is rapid near room temperature and the nonadiabatic path is accelerated by a barrier that is 40 kJ mol-1 less than the adiabatic path. Simulated thermal desorption reactions using nonadiabatic transition state theory (NA-TST) for the surface dimer intersystem crossing are in close agreement with experimental observations.
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Affiliation(s)
- Andrew J Pohlman
- Department of Chemistry and Chemical Physics Program, University of Nevada, 1664 N. Virginia Street, Reno, Nevada 89557-0216, USA.
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18
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Gordon OM, Moriarty PJ. Machine learning at the (sub)atomic scale: next generation scanning probe microscopy. MACHINE LEARNING-SCIENCE AND TECHNOLOGY 2020. [DOI: 10.1088/2632-2153/ab7d2f] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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19
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Braun C, Neufeld S, Gerstmann U, Sanna S, Plaickner J, Speiser E, Esser N, Schmidt WG. Vibration-Driven Self-Doping of Dangling-Bond Wires on Si(553)-Au Surfaces. PHYSICAL REVIEW LETTERS 2020; 124:146802. [PMID: 32338960 DOI: 10.1103/physrevlett.124.146802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/21/2020] [Indexed: 06/11/2023]
Abstract
Density-functional theory is used to explore the Si(553)-Au surface dynamics. Our study (i) reveals a complex two-stage order-disorder phase transition where with rising temperature first the ×3 order along the Si step edges and, subsequently, the ×2 order of the Au chains is lost, (ii) identifies the transient modification of the electron chemical potential during soft Au chain vibrations as instrumental for disorder at the step edge, and (iii) shows that the transition leads to a self-doping of the Si dangling-bond wire at the step edge. The calculations are corroborated by Raman measurements of surface phonon modes and explain previous electron diffraction, scanning tunneling microscopy, and surface transport data.
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Affiliation(s)
- C Braun
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
| | - S Neufeld
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
| | - U Gerstmann
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
| | - S Sanna
- Institut für Theoretische Physik and Center for Materials Research, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany
| | - J Plaickner
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V. Schwarzschildstr. 8, 12489 Berlin, Germany
| | - E Speiser
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V. Schwarzschildstr. 8, 12489 Berlin, Germany
| | - N Esser
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V. Schwarzschildstr. 8, 12489 Berlin, Germany
- Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin, Germany
| | - W G Schmidt
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
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20
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Achal R, Rashidi M, Croshaw J, Huff TR, Wolkow RA. Detecting and Directing Single Molecule Binding Events on H-Si(100) with Application to Ultradense Data Storage. ACS NANO 2020; 14:2947-2955. [PMID: 31773956 DOI: 10.1021/acsnano.9b07637] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Many diverse material systems are being explored to enable smaller, more capable and energy efficient devices. These bottom up approaches for atomic and molecular electronics, quantum computation, and data storage all rely on a well-developed understanding of materials at the atomic scale. Here, we report a versatile scanning tunneling microscope (STM) charge characterization technique, which reduces the influence of the typically perturbative STM tip field, to develop this understanding even further. Using this technique, we can now observe single molecule binding events to atomically defined reactive sites (fabricated on a hydrogen-terminated silicon surface) through electronic detection. We then developed a simplified error correction tool for automated hydrogen lithography, quickly directing molecular hydrogen binding events using these sites to precisely repassivate surface dangling bonds (without the use of a scanned probe). We additionally incorporated this molecular repassivation technique as the primary rewriting mechanism in ultradense atomic data storage designs (0.88 petabits per in2).
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Affiliation(s)
- Roshan Achal
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
- Quantum Silicon, Inc., Edmonton, Alberta T6G 2M9, Canada
| | - Mohammad Rashidi
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
- Quantum Silicon, Inc., Edmonton, Alberta T6G 2M9, Canada
| | - Jeremiah Croshaw
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
- Quantum Silicon, Inc., Edmonton, Alberta T6G 2M9, Canada
| | - Taleana R Huff
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
- Quantum Silicon, Inc., Edmonton, Alberta T6G 2M9, Canada
| | - Robert A Wolkow
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
- Quantum Silicon, Inc., Edmonton, Alberta T6G 2M9, Canada
- Nanotechnology Research Centre, National Research Council of Canada, Edmonton, Alberta T6G 2M9, Canada
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21
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Rashidi M, Croshaw J, Mastel K, Tamura M, Hosseinzadeh H, Wolkow RA. Deep learning-guided surface characterization for autonomous hydrogen lithography. MACHINE LEARNING-SCIENCE AND TECHNOLOGY 2020. [DOI: 10.1088/2632-2153/ab6d5e] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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An Q, Hu C, Yu G, Guo H. Spin-polarized quantum transport in Si dangling bond wires. NANOSCALE 2020; 12:6079-6088. [PMID: 32129403 DOI: 10.1039/d0nr00037j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report theoretical modeling of spin-dependent quantum transport properties of dangling bond wires (DBWs) on the Si(100)-2 × 1:H surface. A single spin-polarized dangling bond center (DBC) near the DBW may strongly affect transport as characterized by anti-resonances or dips in the transmission spectra. Such spin-dependent gating can be effective up to a distance of 1.5 nanometer between the DBW and the DBC. At the energies where anti-resonances occur, the scattering states of the system are found to be "attracted" to the DBC - rather than moving forward to the existing electrode. The variety of gating effects can be well organized by a physical picture, i.e. a strong hybridization or interaction between the spin-polarized DBW and DBC occurs with the same spin polarization (at DBW and DBC) and at similar energy. The sharp spin-resolved anti-resonance in the DBW gives rise to a spin-filtering effect up to 100% efficiency.
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Affiliation(s)
- Qi An
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China and Department of Physics, McGill University, 3600 rue university, Montréal, Québec H3A 2T8, Canada. and Department of Engineering Physics, École Polytechnique de Montréal, C. P. 6079, Succursale Centre-Ville, Montréal, Québec H3C 3A7, Canada
| | - Chen Hu
- Department of Physics, McGill University, 3600 rue university, Montréal, Québec H3A 2T8, Canada.
| | - Guanghua Yu
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China
| | - Hong Guo
- Department of Physics, McGill University, 3600 rue university, Montréal, Québec H3A 2T8, Canada.
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23
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Fu M, Liang L, Zou Q, Nguyen GD, Xiao K, Li AP, Kang J, Wu Z, Gai Z. Defects in Highly Anisotropic Transition-Metal Dichalcogenide PdSe 2. J Phys Chem Lett 2020; 11:740-746. [PMID: 31880944 DOI: 10.1021/acs.jpclett.9b03312] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The atomic and electronic structures of pristine PdSe2 as well as various intrinsic vacancy defects in PdSe2 are studied comprehensively by combining scanning tunneling microscopy, spectroscopy, and density functional theory calculations. Other than the topmost Se atoms, sublayer Pd atoms and the intrinsic Pd and Se vacancy defects are identified. Both VSe and VPd defects induce defect states near the Fermi level. As a result, the vacancy defects can be negatively charged by a tip gating effect. At negative sample bias, the screened Coulomb interaction between the scanning tunneling microscopy (STM) tip and the charged vacancies creates a disk-like protrusion around the VPd and crater-like features around VSe. The magnification effect of the long-range charge localization at the charged defect site makes sublayer defects as deep as 1 nm visible even in STM images. This result proves that by gating the probe, scanning probe microscopy can be used as an easy tool for characterizing sublayer defects in a nondestructive way.
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Affiliation(s)
- Mingming Fu
- Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics , Xiamen University , Xiamen , Fujian Province 361005 , P.R. China
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Liangbo Liang
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Qiang Zou
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Giang D Nguyen
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Kai Xiao
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - An-Ping Li
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Junyong Kang
- Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics , Xiamen University , Xiamen , Fujian Province 361005 , P.R. China
| | - Zhiming Wu
- Fujian Provincial Key Laboratory of Semiconductors and Applications, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Department of Physics , Xiamen University , Xiamen , Fujian Province 361005 , P.R. China
| | - Zheng Gai
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
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24
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Huff TR, Dienel T, Rashidi M, Achal R, Livadaru L, Croshaw J, Wolkow RA. Electrostatic Landscape of a Hydrogen-Terminated Silicon Surface Probed by a Moveable Quantum Dot. ACS NANO 2019; 13:10566-10575. [PMID: 31386340 DOI: 10.1021/acsnano.9b04653] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
With nanoelectronics reaching the limit of atom-sized devices, it has become critical to examine how irregularities in the local environment can affect device functionality. Here, we characterize the influence of charged atomic species on the electrostatic potential of a semiconductor surface at the subnanometer scale. Using noncontact atomic force microscopy, two-dimensional maps of the contact potential difference are used to show the spatially varying electrostatic potential on the (100) surface of hydrogen-terminated highly doped silicon. Three types of charged species, one on the surface and two within the bulk, are examined. An electric field sensitive spectroscopic signature of a single probe atom reports on nearby charged species. The identity of one of the near-surface species has been uncertain in the literature, and we suggest that its character is more consistent with either a negatively charged interstitial hydrogen or a hydrogen vacancy complex.
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Affiliation(s)
- Taleana R Huff
- Department of Physics , University of Alberta , Edmonton , Alberta T6G 2J1 , Canada
- Quantum Silicon, Inc. , Edmonton , Alberta T6G 2M9 , Canada
| | - Thomas Dienel
- Department of Physics , University of Alberta , Edmonton , Alberta T6G 2J1 , Canada
| | - Mohammad Rashidi
- Department of Physics , University of Alberta , Edmonton , Alberta T6G 2J1 , Canada
| | - Roshan Achal
- Department of Physics , University of Alberta , Edmonton , Alberta T6G 2J1 , Canada
- Quantum Silicon, Inc. , Edmonton , Alberta T6G 2M9 , Canada
| | | | - Jeremiah Croshaw
- Department of Physics , University of Alberta , Edmonton , Alberta T6G 2J1 , Canada
| | - Robert A Wolkow
- Department of Physics , University of Alberta , Edmonton , Alberta T6G 2J1 , Canada
- Nanotechnology Research Centre , National Research Council Canada , Edmonton , Alberta T6G 2M9 , Canada
- Quantum Silicon, Inc. , Edmonton , Alberta T6G 2M9 , Canada
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25
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Iatalese M, Coluccio ML, Onesto V, Amato F, Di Fabrizio E, Gentile F. Relating the rate of growth of metal nanoparticles to cluster size distribution in electroless deposition. NANOSCALE ADVANCES 2019; 1:228-240. [PMID: 36132476 PMCID: PMC9473164 DOI: 10.1039/c8na00040a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 07/23/2018] [Indexed: 06/15/2023]
Abstract
Electroless deposition on patterned silicon substrates enables the formation of metal nanomaterials with tight control over their size and shape. In the technique, metal ions are transported by diffusion from a solution to the active sites of an autocatalytic substrate where they are reduced as metals upon contact. Here, using diffusion limited aggregation models and numerical simulations, we derived relationships that correlate the cluster size distribution to the total mass of deposited particles. We found that the ratio ξ between the rates of growth of two different metals depends on the ratio γ between the rates of growth of clusters formed by those metals through the linearity law ξ = 14(γ - 1). We then validated the model using experiments. Different from other methods, the model derives k using as input the geometry of metal nanoparticle clusters, decoded by SEM or AFM images of samples, and a known reference.
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Affiliation(s)
- M Iatalese
- Akka Technologies Via Giacomo Leopardi 6 40122 Bologna Italy
| | - M L Coluccio
- Department of Experimental and Clinical Medicine, University Magna Graecia 88100 Catanzaro Italy
| | - V Onesto
- Department of Experimental and Clinical Medicine, University Magna Graecia 88100 Catanzaro Italy
| | - F Amato
- Department of Experimental and Clinical Medicine, University Magna Graecia 88100 Catanzaro Italy
| | - E Di Fabrizio
- Physical Science & Engineering Division, King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia
| | - F Gentile
- Department of Electrical Engineering and Information Technology, University Federico II 80125 Naples Italy
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26
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Wyrick J, Wang X, Namboodiri P, Schmucker SW, Kashid RV, Silver RM. Atom-by-Atom Construction of a Cyclic Artificial Molecule in Silicon. NANO LETTERS 2018; 18:7502-7508. [PMID: 30428677 PMCID: PMC6505699 DOI: 10.1021/acs.nanolett.8b02919] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Hydrogen atoms on a silicon surface, H-Si (100), behave as a resist that can be patterned with perfect atomic precision using a scanning tunneling microscope. When a hydrogen atom is removed in this manner, the underlying silicon presents a chemically active site, commonly referred to as a dangling bond. It has been predicted that individual dangling bonds function as artificial atoms, which, if grouped together, can form designer molecules on the H-Si (100) surface. Here, we present an artificial ring structure molecule spanning three dimer rows, constructed from dangling bonds, and verified by spectroscopic measurement of its molecular orbitals. We found that removing 8 hydrogen atoms resulted in a molecular analog to 1,4-disilylene-hexasilabenzene (Si8H8). Scanning tunneling spectroscopic measurements reveal molecular π and π* orbitals that agree with those expected for the same molecule in a vacuum; this is validated by density functional theory calculations of the dangling bond system on a silicon slab that show direct links both to the experimental results and to calculations for the isolated molecule. We believe the unique electronic structure of artificial molecules constructed in this manner can be engineered to enable future molecule-based electronics, surface catalytic functionality, and templating for subsequent site-selective deposition.
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Affiliation(s)
- Jonathan Wyrick
- Nanoscale Device Characterization Division, National Institute for Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Xiqiao Wang
- Nanoscale Device Characterization Division, National Institute for Standards and Technology, Gaithersburg, Maryland 20899, United States
- Chemical Physics Program, University of Maryland, College Park, Maryland 20742, United States
| | - Pradeep Namboodiri
- Nanoscale Device Characterization Division, National Institute for Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Scott W. Schmucker
- Nanoscale Device Characterization Division, National Institute for Standards and Technology, Gaithersburg, Maryland 20899, United States
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, United States
| | - Ranjit V. Kashid
- Nanoscale Device Characterization Division, National Institute for Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Richard M. Silver
- Nanoscale Device Characterization Division, National Institute for Standards and Technology, Gaithersburg, Maryland 20899, United States
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27
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Rashidi M, Vine W, Dienel T, Livadaru L, Retallick J, Huff T, Walus K, Wolkow RA. Initiating and Monitoring the Evolution of Single Electrons Within Atom-Defined Structures. PHYSICAL REVIEW LETTERS 2018; 121:166801. [PMID: 30387671 DOI: 10.1103/physrevlett.121.166801] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 07/24/2018] [Indexed: 06/08/2023]
Abstract
Using a noncontact atomic force microscope, we track and manipulate the position of single electrons confined to atomic structures engineered from silicon dangling bonds on the hydrogen terminated silicon surface. An attractive tip surface interaction mechanically manipulates the equilibrium position of a surface silicon atom, causing rehybridization that stabilizes a negative charge at the dangling bond. This is applied to controllably switch the charge state of individual dangling bonds. Because this mechanism is based on short range interactions and can be performed without applied bias voltage, we maintain both site-specific selectivity and single-electron control. We extract the short range forces involved with this mechanism by subtracting the long range forces acquired on a dimer vacancy site. As a result of relaxation of the silicon lattice to accommodate negatively charged dangling bonds, we observe charge configurations of dangling bond structures that remain stable for many seconds at 4.5 K. Subsequently, we use charge manipulation to directly prepare the ground state and metastable charge configurations of dangling bond structures composed of up to six atoms.
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Affiliation(s)
- Mohammad Rashidi
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada
- Nanotechnology Initiative, Edmonton, AB, Canada, T6G 2M9
- Quantum Silicon, Edmonton, AB, Canada, T6G 2M9
| | - Wyatt Vine
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada
| | - Thomas Dienel
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada
- Nanotechnology Initiative, Edmonton, AB, Canada, T6G 2M9
| | | | - Jacob Retallick
- Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Taleana Huff
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada
- Quantum Silicon, Edmonton, AB, Canada, T6G 2M9
| | - Konrad Walus
- Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Robert A Wolkow
- Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada
- Nanotechnology Initiative, Edmonton, AB, Canada, T6G 2M9
- Quantum Silicon, Edmonton, AB, Canada, T6G 2M9
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28
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Achal R, Rashidi M, Croshaw J, Churchill D, Taucer M, Huff T, Cloutier M, Pitters J, Wolkow RA. Lithography for robust and editable atomic-scale silicon devices and memories. Nat Commun 2018; 9:2778. [PMID: 30038236 PMCID: PMC6056515 DOI: 10.1038/s41467-018-05171-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 06/15/2018] [Indexed: 12/02/2022] Open
Abstract
At the atomic scale, there has always been a trade-off between the ease of fabrication of structures and their thermal stability. Complex structures that are created effortlessly often disorder above cryogenic conditions. Conversely, systems with high thermal stability do not generally permit the same degree of complex manipulations. Here, we report scanning tunneling microscope (STM) techniques to substantially improve automated hydrogen lithography (HL) on silicon, and to transform state-of-the-art hydrogen repassivation into an efficient, accessible error correction/editing tool relative to existing chemical and mechanical methods. These techniques are readily adapted to many STMs, together enabling fabrication of error-free, room-temperature stable structures of unprecedented size. We created two rewriteable atomic memories (1.1 petabits per in2), storing the alphabet letter-by-letter in 8 bits and a piece of music in 192 bits. With HL no longer faced with this trade-off, practical silicon-based atomic-scale devices are poised to make rapid advances towards their full potential. Manipulation at the atomic scale comes with a trade-off between simplicity and thermal stability. Here, Achal et al. demonstrate improved automated hydrogen lithography and repassivation, enabling error-corrected atomic writing of large-scale structures/memories that are stable at room temperature.
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Affiliation(s)
- Roshan Achal
- Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada. .,Quantum Silicon, Inc., Edmonton, AB, T6G 2M9, Canada.
| | - Mohammad Rashidi
- Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada.,Quantum Silicon, Inc., Edmonton, AB, T6G 2M9, Canada
| | - Jeremiah Croshaw
- Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada
| | - David Churchill
- Memorial University of Newfoundland, St. John's, NL, A1B 3X5, Canada
| | - Marco Taucer
- Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada.,Quantum Silicon, Inc., Edmonton, AB, T6G 2M9, Canada
| | - Taleana Huff
- Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada.,Quantum Silicon, Inc., Edmonton, AB, T6G 2M9, Canada
| | - Martin Cloutier
- Nanotechnology Research Centre, National Research Council of Canada, Edmonton, AB, T6G 2M9, Canada
| | - Jason Pitters
- Quantum Silicon, Inc., Edmonton, AB, T6G 2M9, Canada.,Nanotechnology Research Centre, National Research Council of Canada, Edmonton, AB, T6G 2M9, Canada
| | - Robert A Wolkow
- Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada.,Quantum Silicon, Inc., Edmonton, AB, T6G 2M9, Canada.,Nanotechnology Research Centre, National Research Council of Canada, Edmonton, AB, T6G 2M9, Canada
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29
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Rashidi M, Wolkow RA. Autonomous Scanning Probe Microscopy in Situ Tip Conditioning through Machine Learning. ACS NANO 2018; 12:5185-5189. [PMID: 29790333 DOI: 10.1021/acsnano.8b02208] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Atomic-scale characterization and manipulation with scanning probe microscopy rely upon the use of an atomically sharp probe. Here we present automated methods based on machine learning to automatically detect and recondition the quality of the probe of a scanning tunneling microscope. As a model system, we employ these techniques on the technologically relevant hydrogen-terminated silicon surface, training the network to recognize abnormalities in the appearance of surface dangling bonds. Of the machine learning methods tested, a convolutional neural network yielded the greatest accuracy, achieving a positive identification of degraded tips in 97% of the test cases. By using multiple points of comparison and majority voting, the accuracy of the method is improved beyond 99%.
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Affiliation(s)
- Mohammad Rashidi
- Department of Physics , University of Alberta , Edmonton , Alberta T6G 2J1 , Canada
- Quantum Silicon, Inc. , Edmonton , Alberta T6G 2M9 , Canada
| | - Robert A Wolkow
- Department of Physics , University of Alberta , Edmonton , Alberta T6G 2J1 , Canada
- Quantum Silicon, Inc. , Edmonton , Alberta T6G 2M9 , Canada
- Nanotechnology Initiative , University of Alberta , Edmonton , Alberta T6G 2M9 , Canada
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30
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Levchenko I, Xu S, Teel G, Mariotti D, Walker MLR, Keidar M. Recent progress and perspectives of space electric propulsion systems based on smart nanomaterials. Nat Commun 2018; 9:879. [PMID: 29491411 PMCID: PMC5830404 DOI: 10.1038/s41467-017-02269-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 11/16/2017] [Indexed: 11/23/2022] Open
Abstract
Drastic miniaturization of electronics and ingression of next-generation nanomaterials into space technology have provoked a renaissance in interplanetary flights and near-Earth space exploration using small unmanned satellites and systems. As the next stage, the NASA's 2015 Nanotechnology Roadmap initiative called for new design paradigms that integrate nanotechnology and conceptually new materials to build advanced, deep-space-capable, adaptive spacecraft. This review examines the cutting edge and discusses the opportunities for integration of nanomaterials into the most advanced types of electric propulsion devices that take advantage of their unique features and boost their efficiency and service life. Finally, we propose a concept of an adaptive thruster.
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Affiliation(s)
- I Levchenko
- Plasma Sources and Applications Centre, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore, 637616, Singapore.
- School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology (QUT), Brisbane, QLD, 4000, Australia.
| | - S Xu
- Plasma Sources and Applications Centre, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore, 637616, Singapore
| | - G Teel
- Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC, 20052, USA
| | - D Mariotti
- Nanotechnology and Integrated Bio-Engineering Centre (NIBEC), Ulster University, Newtownabbey, BT37 0QB, UK
| | - M L R Walker
- School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0150, USA
| | - M Keidar
- Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC, 20052, USA
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31
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Rashidi M, Vine W, Burgess JAJ, Taucer M, Achal R, Pitters JL, Loth S, Wolkow RA. All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics. J Vis Exp 2018. [PMID: 29443038 DOI: 10.3791/56861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The miniaturization of semiconductor devices to scales where small numbers of dopants can control device properties requires the development of new techniques capable of characterizing their dynamics. Investigating single dopants requires sub-nanometer spatial resolution, which motivates the use of scanning tunneling microscopy (STM). However, conventional STM is limited to millisecond temporal resolution. Several methods have been developed to overcome this shortcoming, including all-electronic time-resolved STM, which is used in this study to examine dopant dynamics in silicon with nanosecond resolution. The methods presented here are widely accessible and allow for local measurement of a wide variety of dynamics at the atomic scale. A novel time-resolved scanning tunneling spectroscopy technique is presented and used to efficiently search for dynamics.
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Affiliation(s)
- Mohammad Rashidi
- Department of Physics, University of Alberta; National Institute for Nanotechnology, National Research Council of Canada, Edmonton;
| | - Wyatt Vine
- Department of Physics, University of Alberta
| | - Jacob A J Burgess
- Max Planck Institute for the Structure and Dynamics of Matter; Max Planck Institute for Solid State Research; Department of Physics and Astronomy, University of Manitoba
| | - Marco Taucer
- Department of Physics, University of Alberta; National Institute for Nanotechnology, National Research Council of Canada, Edmonton; Joint Attosecond Science Laboratory, University of Ottawa
| | | | - Jason L Pitters
- National Institute for Nanotechnology, National Research Council of Canada, Edmonton
| | - Sebastian Loth
- Max Planck Institute for the Structure and Dynamics of Matter; Max Planck Institute for Solid State Research
| | - Robert A Wolkow
- Department of Physics, University of Alberta; National Institute for Nanotechnology, National Research Council of Canada, Edmonton
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32
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Zhang J, Ji WX, Zhang CW, Li P, Wang PJ. Nontrivial topology and topological phase transition in two-dimensional monolayer Tl. Phys Chem Chem Phys 2018; 20:24790-24795. [DOI: 10.1039/c8cp02649a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Topological insulating material with dissipationless edge states is a rising star in spintronics.
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Affiliation(s)
- Jin Zhang
- School of Physics and Technology
- University of Jinan
- Jinan
- People's Republic of China
| | - Wei-xiao Ji
- School of Physics and Technology
- University of Jinan
- Jinan
- People's Republic of China
| | - Chang-wen Zhang
- School of Physics and Technology
- University of Jinan
- Jinan
- People's Republic of China
| | - Ping Li
- School of Physics and Technology
- University of Jinan
- Jinan
- People's Republic of China
| | - Pei-ji Wang
- School of Physics and Technology
- University of Jinan
- Jinan
- People's Republic of China
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33
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Godlewski S, Engelund M, Peña D, Zuzak R, Kawai H, Kolmer M, Caeiro J, Guitián E, Vollhardt KPC, Sánchez-Portal D, Szymonski M, Pérez D. Site-selective reversible Diels–Alder reaction between a biphenylene-based polyarene and a semiconductor surface. Phys Chem Chem Phys 2018; 20:11037-11046. [DOI: 10.1039/c8cp01094c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A multidisciplinary study reveals the chemistry of a polycyclic conjugated molecule on a Ge(001):H surface.
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Affiliation(s)
- Szymon Godlewski
- Centre for Nanometer-Scale Science and Advanced Materials
- NANOSAM
- Faculty of Physics
- Astronomy and Applied Computer Science
- Jagiellonian University
| | - Mads Engelund
- Centro de Física de Materiales CSIC-UPV/EHU and DIPC
- Donostia-San Sebastián
- Spain
| | - Diego Peña
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica
- Universidade de Santiago de Compostela
- 15782 Santiago de Compostela
- Spain
| | - Rafał Zuzak
- Centre for Nanometer-Scale Science and Advanced Materials
- NANOSAM
- Faculty of Physics
- Astronomy and Applied Computer Science
- Jagiellonian University
| | - Hiroyo Kawai
- Institute of Materials Research and Engineering
- 138634 Singapore
| | - Marek Kolmer
- Centre for Nanometer-Scale Science and Advanced Materials
- NANOSAM
- Faculty of Physics
- Astronomy and Applied Computer Science
- Jagiellonian University
| | - Jorge Caeiro
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica
- Universidade de Santiago de Compostela
- 15782 Santiago de Compostela
- Spain
| | - Enrique Guitián
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica
- Universidade de Santiago de Compostela
- 15782 Santiago de Compostela
- Spain
| | | | | | - Marek Szymonski
- Centre for Nanometer-Scale Science and Advanced Materials
- NANOSAM
- Faculty of Physics
- Astronomy and Applied Computer Science
- Jagiellonian University
| | - Dolores Pérez
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica
- Universidade de Santiago de Compostela
- 15782 Santiago de Compostela
- Spain
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34
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Yengui M, Duverger E, Sonnet P, Riedel D. A two-dimensional ON/OFF switching device based on anisotropic interactions of atomic quantum dots on Si(100):H. Nat Commun 2017; 8:2211. [PMID: 29263380 PMCID: PMC5738427 DOI: 10.1038/s41467-017-02377-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 11/23/2017] [Indexed: 11/09/2022] Open
Abstract
Controlling the properties of quantum dots at the atomic scale, such as dangling bonds, is a general motivation as they allow studying various nanoscale processes including atomic switches, charge storage, or low binding energy state interactions. Adjusting the coupling of individual silicon dangling bonds to form a 2D device having a defined function remains a challenge. Here, we exploit the anisotropic interactions between silicon dangling bonds on n-type doped Si(100):H surface to tune their hybridization. This process arises from interactions between the subsurface silicon network and dangling bonds inducing a combination of Jahn-Teller distortions and local charge ordering. A three-pointed star-shaped device prototype is designed. By changing the charge state of this device, its electronic properties are shown to switch reversibly from an ON to an OFF state via local change of its central gap. Our results provide a playground for the study of quantum information at the nanoscale.
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Affiliation(s)
- Mayssa Yengui
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris Sud, Université Paris-Saclay, 91405, Orsay, France
| | - Eric Duverger
- Institut FEMTO-ST, Univ. Bourgogne Franche-Comté, CNRS, 15B avenue des Montboucons, 25030, Besançon, France
| | - Philippe Sonnet
- Institut de Science des Matériaux de Mulhouse (IS2M), CNRS, UMR 7361, Université de Haute Alsace, 3 bis rue Alfred Werner, 68057, Mulhouse, France
| | - Damien Riedel
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris Sud, Université Paris-Saclay, 91405, Orsay, France.
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35
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Rashidi M, Lloyd E, Huff TR, Achal R, Taucer M, Croshaw JJ, Wolkow RA. Resolving and Tuning Carrier Capture Rates at a Single Silicon Atom Gap State. ACS NANO 2017; 11:11732-11738. [PMID: 29091424 DOI: 10.1021/acsnano.7b07068] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on tuning the carrier capture events at a single dangling bond (DB) midgap state by varying the substrate temperature, doping type, and doping concentration. All-electronic time-resolved scanning tunneling microscopy (TR-STM) is employed to directly measure the carrier capture rates on the nanosecond time scale. A characteristic negative differential resistance (NDR) feature is evident in the scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) measurements of DBs on both n- and p-type doped samples. We find that a common model accounts for both observations. Atom-specific Kelvin probe force microscopy (KPFM) measurements confirm the energetic position of the DB's charge transition levels, corroborating STS studies. We show that under different tip-induced fields the DB can be supplied with electrons from two distinct reservoirs: the bulk conduction band and/or the valence band. We measure the filling and emptying rates of the DBs in the energy regime where electrons are supplied by the bulk valence band. We show that adding point charges in the vicinity of a DB shifts observed STS and NDR features due to Coulombic interactions.
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Affiliation(s)
- Mohammad Rashidi
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2J1, Canada
- National Institute for Nanotechnology, National Research Council of Canada , Edmonton, Alberta T6G 2M9, Canada
| | - Erika Lloyd
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2J1, Canada
| | - Taleana R Huff
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2J1, Canada
- Quantum Silicon, Inc., Edmonton, Alberta T6G 2M9, Canada
| | - Roshan Achal
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2J1, Canada
- Quantum Silicon, Inc., Edmonton, Alberta T6G 2M9, Canada
| | - Marco Taucer
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2J1, Canada
| | - Jeremiah J Croshaw
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2J1, Canada
| | - Robert A Wolkow
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2J1, Canada
- National Institute for Nanotechnology, National Research Council of Canada , Edmonton, Alberta T6G 2M9, Canada
- Quantum Silicon, Inc., Edmonton, Alberta T6G 2M9, Canada
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36
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Huff TR, Labidi H, Rashidi M, Koleini M, Achal R, Salomons MH, Wolkow RA. Atomic White-Out: Enabling Atomic Circuitry through Mechanically Induced Bonding of Single Hydrogen Atoms to a Silicon Surface. ACS NANO 2017; 11:8636-8642. [PMID: 28719182 DOI: 10.1021/acsnano.7b04238] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the mechanically induced formation of a silicon-hydrogen covalent bond and its application in engineering nanoelectronic devices. We show that using the tip of a noncontact atomic force microscope (NC-AFM), a single hydrogen atom could be vertically manipulated. When applying a localized electronic excitation, a single hydrogen atom is desorbed from the hydrogen-passivated surface and can be transferred to the tip apex, as evidenced from a unique signature in frequency shift curves. In the absence of tunnel electrons and electric field in the scanning probe microscope junction at 0 V, the hydrogen atom at the tip apex is brought very close to a silicon dangling bond, inducing the mechanical formation of a silicon-hydrogen covalent bond and the passivation of the dangling bond. The functionalized tip was used to characterize silicon dangling bonds on the hydrogen-silicon surface, which was shown to enhance the scanning tunneling microscope contrast, and allowed NC-AFM imaging with atomic and chemical bond contrasts. Through examples, we show the importance of this atomic-scale mechanical manipulation technique in the engineering of the emerging technology of on-surface dangling bond based nanoelectronic devices.
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Affiliation(s)
- Taleana R Huff
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2E1, Canada
- Quantum Silicon, Inc. , Edmonton, Alberta T6G 2M9, Canada
| | - Hatem Labidi
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2E1, Canada
- National Institute for Nanotechnology, National Research Council of Canada , Edmonton, Alberta T6G 2M9, Canada
| | - Mohammad Rashidi
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2E1, Canada
- National Institute for Nanotechnology, National Research Council of Canada , Edmonton, Alberta T6G 2M9, Canada
| | - Mohammad Koleini
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2E1, Canada
- National Institute for Nanotechnology, National Research Council of Canada , Edmonton, Alberta T6G 2M9, Canada
| | - Roshan Achal
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2E1, Canada
- Quantum Silicon, Inc. , Edmonton, Alberta T6G 2M9, Canada
| | - Mark H Salomons
- Quantum Silicon, Inc. , Edmonton, Alberta T6G 2M9, Canada
- National Institute for Nanotechnology, National Research Council of Canada , Edmonton, Alberta T6G 2M9, Canada
| | - Robert A Wolkow
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2E1, Canada
- Quantum Silicon, Inc. , Edmonton, Alberta T6G 2M9, Canada
- National Institute for Nanotechnology, National Research Council of Canada , Edmonton, Alberta T6G 2M9, Canada
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37
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Møller M, Jarvis SP, Guérinet L, Sharp P, Woolley R, Rahe P, Moriarty P. Automated extraction of single H atoms with STM: tip state dependency. NANOTECHNOLOGY 2017; 28:075302. [PMID: 28074783 DOI: 10.1088/1361-6528/28/7/075302] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The atomistic structure of the tip apex plays a crucial role in performing reliable atomic-scale surface and adsorbate manipulation using scanning probe techniques. We have developed an automated extraction routine for controlled removal of single hydrogen atoms from the H:Si(100) surface. The set of atomic extraction protocols detect a variety of desorption events during scanning tunneling microscope (STM)-induced modification of the hydrogen-passivated surface. The influence of the tip state on the probability for hydrogen removal was examined by comparing the desorption efficiency for various classifications of STM topographs (rows, dimers, atoms, etc). We find that dimer-row-resolving tip apices extract hydrogen atoms most readily and reliably (and with least spurious desorption), while tip states which provide atomic resolution counter-intuitively have a lower probability for single H atom removal.
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Affiliation(s)
- Morten Møller
- School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, UK
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38
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Labidi H, Koleini M, Huff T, Salomons M, Cloutier M, Pitters J, Wolkow RA. Indications of chemical bond contrast in AFM images of a hydrogen-terminated silicon surface. Nat Commun 2017; 8:14222. [PMID: 28194036 PMCID: PMC5316802 DOI: 10.1038/ncomms14222] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 12/08/2016] [Indexed: 01/05/2023] Open
Abstract
The origin of bond-resolved atomic force microscope images remains controversial. Moreover, most work to date has involved planar, conjugated hydrocarbon molecules on a metal substrate thereby limiting knowledge of the generality of findings made about the imaging mechanism. Here we report the study of a very different sample; a hydrogen-terminated silicon surface. A procedure to obtain a passivated hydrogen-functionalized tip is defined and evolution of atomic force microscopy images at different tip elevations are shown. At relatively large tip-sample distances, the topmost atoms appear as distinct protrusions. However, on decreasing the tip-sample distance, features consistent with the silicon covalent bonds of the surface emerge. Using a density functional tight-binding-based method to simulate atomic force microscopy images, we reproduce the experimental results. The role of the tip flexibility and the nature of bonds and false bond-like features are discussed. Whether and under what circumstances chemical bonds could be imaged via force microscopy is a controversial topic. Here authors develop a particular combination of model surface, imaging procedures and simulation approach and discuss possible indications of chemical contrast in imaging data they obtain.
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Affiliation(s)
- Hatem Labidi
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2J1.,National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta, Canada T6G 2M9
| | - Mohammad Koleini
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2J1.,National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta, Canada T6G 2M9
| | - Taleana Huff
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2J1
| | - Mark Salomons
- National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta, Canada T6G 2M9
| | - Martin Cloutier
- National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta, Canada T6G 2M9
| | - Jason Pitters
- National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta, Canada T6G 2M9
| | - Robert A Wolkow
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2J1.,National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta, Canada T6G 2M9
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39
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Chiu SP, Yeh SS, Chiou CJ, Chou YC, Lin JJ, Tsuei CC. Ultralow 1/f Noise in a Heterostructure of Superconducting Epitaxial Cobalt Disilicide Thin Film on Silicon. ACS NANO 2017; 11:516-525. [PMID: 28027434 DOI: 10.1021/acsnano.6b06553] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
High-precision resistance noise measurements indicate that the epitaxial CoSi2/Si heterostructures at 150 and 2 K (slightly above its superconducting transition temperature Tc of 1.54 K) exhibit an unusually low 1/f noise level in the frequency range of 0.008-0.2 Hz. This corresponds to an upper limit of Hooge constant γ ≤ 3 × 10-6, about 100 times lower than that of single-crystalline aluminum films on SiO2 capped Si substrates. Supported by high-resolution cross-sectional transmission electron microscopy studies, our analysis reveals that the 1/f noise is dominated by excess interfacial Si atoms and their dimer reconstruction induced fluctuators. Unbonded orbitals (i.e., dangling bonds) on excess Si atoms are intrinsically rare at the epitaxial CoSi2/Si(100) interface, giving limited trapping-detrapping centers for localized charges. With its excellent normal-state properties, CoSi2 has been used in silicon-based integrated circuits for decades. The intrinsically low noise properties discovered in this work could be utilized for developing quiet qubits and scalable superconducting circuits for future quantum computing.
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Affiliation(s)
| | | | | | | | | | - Chang-Chyi Tsuei
- IBM Thomas J. Watson Research Center , Yorktown Heights, New York 10598, United States
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40
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Bohloul S, Shi Q, Wolkow RA, Guo H. Quantum Transport in Gated Dangling-Bond Atomic Wires. NANO LETTERS 2017; 17:322-327. [PMID: 28073256 DOI: 10.1021/acs.nanolett.6b04125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A single line of dangling bonds (DBs) on Si(100)-2 × 1:H surface forms a perfect metallic atomic-wire. In this work, we investigate quantum transport properties of such dangling bond wires (DBWs) by a state-of-the-art first-principles technique. It is found that the conductance of the DBW can be gated by electrostatic potential and orbital overlap due to only a single DB center (DBC) within a distance of ∼16 Å from the DBW. The gating effect is more pronounced for two DBCs and especially, when these two DB "gates" are within ∼3.9 Å from each other. These effective length scales are in excellent agreement with those measured in scanning tunnelling microscope experiments. By analyzing transmission spectrum and density of states of DBC-DBW systems, with or without subsurface doping, for different length of the DBW, distance between DBCs and the DBW, and distance between DB gates, we conclude that charge transport in a DBW can be regulated to have both an on-state and an off-state using only one or two DBs.
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Affiliation(s)
- S Bohloul
- Center for the Physics of Materials and Department of Physics, McGill University , Montreal, Quebec H3A 2T8, Canada
| | - Q Shi
- Center for the Physics of Materials and Department of Physics, McGill University , Montreal, Quebec H3A 2T8, Canada
| | - Robert A Wolkow
- National Institute for Nanotechnology, National Research Council of Canada , Edmonton, Alberta T6G 2M9, Canada
- Department of Physics, University of Alberta , Edmonton, Alberta T6G 2E1, Canada
| | - Hong Guo
- Center for the Physics of Materials and Department of Physics, McGill University , Montreal, Quebec H3A 2T8, Canada
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41
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Nanoplasmonic and Microfluidic Devices for Biological Sensing. NATO SCIENCE FOR PEACE AND SECURITY SERIES B: PHYSICS AND BIOPHYSICS 2017. [DOI: 10.1007/978-94-024-0850-8_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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42
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Fthenakis ZG. Are the experimentally observed 3-dimensional carbon honeycombs all-sp2 structures? The dangling p-orbital instability. RSC Adv 2017. [DOI: 10.1039/c6ra27833g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
3-Dimensional all-sp2 honeycomb carbon structures are unstable, due to dangling bonds, formed on the junction atom unhybridized p-orbitals.
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43
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Rashidi M, Taucer M, Ozfidan I, Lloyd E, Koleini M, Labidi H, Pitters JL, Maciejko J, Wolkow RA. Time-Resolved Imaging of Negative Differential Resistance on the Atomic Scale. PHYSICAL REVIEW LETTERS 2016; 117:276805. [PMID: 28084769 DOI: 10.1103/physrevlett.117.276805] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Indexed: 06/06/2023]
Abstract
Negative differential resistance remains an attractive but elusive functionality, so far only finding niche applications. Atom scale entities have shown promising properties, but the viability of device fabrication requires a fuller understanding of electron dynamics than has been possible to date. Using an all-electronic time-resolved scanning tunneling microscopy technique and a Green's function transport model, we study an isolated dangling bond on a hydrogen terminated silicon surface. A robust negative differential resistance feature is identified as a many body phenomenon related to occupation dependent electron capture by a single atomic level. We measure all the time constants involved in this process and present atomically resolved, nanosecond time scale images to simultaneously capture the spatial and temporal variation of the observed feature.
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Affiliation(s)
- Mohammad Rashidi
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
- National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta T6G 2M9, Canada
| | - Marco Taucer
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
- National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta T6G 2M9, Canada
| | - Isil Ozfidan
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
| | - Erika Lloyd
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
| | - Mohammad Koleini
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
- National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta T6G 2M9, Canada
| | - Hatem Labidi
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
- National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta T6G 2M9, Canada
| | - Jason L Pitters
- National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta T6G 2M9, Canada
| | - Joseph Maciejko
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
- Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
| | - Robert A Wolkow
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
- National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta T6G 2M9, Canada
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44
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Passivation and characterization of charge defects in ambipolar silicon quantum dots. Sci Rep 2016; 6:38127. [PMID: 27922048 PMCID: PMC5138628 DOI: 10.1038/srep38127] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 11/07/2016] [Indexed: 11/24/2022] Open
Abstract
In this Report we show the role of charge defects in the context of the formation of electrostatically defined quantum dots. We introduce a barrier array structure to probe defects at multiple locations in a single device. We measure samples both before and after an annealing process which uses an Al2O3 overlayer, grown by atomic layer deposition. After passivation of the majority of charge defects with annealing we can electrostatically define hole quantum dots up to 180 nm in length. Our ambipolar structures reveal amphoteric charge defects that remain after annealing with charging energies of 10 meV in both the positive and negative charge state.
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45
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Rusimova KR, Bannister N, Harrison P, Lock D, Crampin S, Palmer RE, Sloan PA. Initiating and imaging the coherent surface dynamics of charge carriers in real space. Nat Commun 2016; 7:12839. [PMID: 27677938 PMCID: PMC5052722 DOI: 10.1038/ncomms12839] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 08/05/2016] [Indexed: 11/09/2022] Open
Abstract
The tip of a scanning tunnelling microscope is an atomic-scale source of electrons and holes. As the injected charge spreads out, it can induce adsorbed molecules to react. By comparing large-scale 'before' and 'after' images of an adsorbate covered surface, the spatial extent of the nonlocal manipulation is revealed. Here, we measure the nonlocal manipulation of toluene molecules on the Si(111)-7 × 7 surface at room temperature. Both the range and probability of nonlocal manipulation have a voltage dependence. A region within 5-15 nm of the injection site shows a marked reduction in manipulation. We propose that this region marks the extent of the initial coherent (that is, ballistic) time-dependent evolution of the injected charge carrier. Using scanning tunnelling spectroscopy, we develop a model of this time-dependent expansion of the initially localized hole wavepacket within a particular surface state and deduce a quantum coherence (ballistic) lifetime of ∼10 fs.
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Affiliation(s)
- K R Rusimova
- Centre for Nanoscience and Nanotechnology, Department of Physics, University of Bath, Bath BA2 7AY, UK.,Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK
| | - N Bannister
- Centre for Nanoscience and Nanotechnology, Department of Physics, University of Bath, Bath BA2 7AY, UK
| | - P Harrison
- Centre for Nanoscience and Nanotechnology, Department of Physics, University of Bath, Bath BA2 7AY, UK
| | - D Lock
- Centre for Nanoscience and Nanotechnology, Department of Physics, University of Bath, Bath BA2 7AY, UK
| | - S Crampin
- Centre for Nanoscience and Nanotechnology, Department of Physics, University of Bath, Bath BA2 7AY, UK
| | - R E Palmer
- Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK
| | - P A Sloan
- Centre for Nanoscience and Nanotechnology, Department of Physics, University of Bath, Bath BA2 7AY, UK
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46
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Godlewski S, Kawai H, Kolmer M, Zuzak R, Echavarren AM, Joachim C, Szymonski M, Saeys M. Single-Molecule Rotational Switch on a Dangling Bond Dimer Bearing. ACS NANO 2016; 10:8499-8507. [PMID: 27504525 DOI: 10.1021/acsnano.6b03590] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
One of the key challenges in the construction of atomic-scale circuits and molecular machines is to design molecular rotors and switches by controlling the linear or rotational movement of a molecule while preserving its intrinsic electronic properties. Here, we demonstrate both the continuous rotational switching and the controlled step-by-step single switching of a trinaphthylene molecule adsorbed on a dangling bond dimer created on a hydrogen-passivated Ge(001):H surface. The molecular switch is on-surface assembled when the covalent bonds between the molecule and the dangling bond dimer are controllably broken, and the molecule is attached to the dimer by long-range van der Waals interactions. In this configuration, the molecule retains its intrinsic electronic properties, as confirmed by combined scanning tunneling microscopy/spectroscopy (STM/STS) measurements, density functional theory calculations, and advanced STM image calculations. Continuous switching of the molecule is initiated by vibronic excitations when the electrons are tunneling through the lowest unoccupied molecular orbital state of the molecule. The switching path is a combination of a sliding and rotation motion over the dangling bond dimer pivot. By carefully selecting the STM conditions, control over discrete single switching events is also achieved. Combined with the ability to create dangling bond dimers with atomic precision, the controlled rotational molecular switch is expected to be a crucial building block for more complex surface atomic-scale devices.
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Affiliation(s)
- Szymon Godlewski
- Centre for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University , Łojasiewicza 11, PL 30-348 Krakow, Poland
| | - Hiroyo Kawai
- Institute of Materials Research and Engineering , 2 Fusionopolis Way, Innovis, #08-03, Singapore 138634
| | - Marek Kolmer
- Centre for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University , Łojasiewicza 11, PL 30-348 Krakow, Poland
| | - Rafał Zuzak
- Centre for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University , Łojasiewicza 11, PL 30-348 Krakow, Poland
| | - Antonio M Echavarren
- Institute of Chemical Research of Catalonia (ICIQ) , Av. Països Catalans 16, 43007 Tarragona, Spain
| | - Christian Joachim
- Nanosciences Group & MANA Satellite, CEMES-CNRS, 29 rue Jeanne Marvig, F-31055 Toulouse, France & International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS) , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Marek Szymonski
- Centre for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University , Łojasiewicza 11, PL 30-348 Krakow, Poland
| | - Mark Saeys
- Laboratory for Chemical Technology, Ghent University , Technologiepark 914, 9052 Ghent, Belgium
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47
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Müller M, Néel N, Crampin S, Kröger J. Lateral Electron Confinement with Open Boundaries: Quantum Well States above Nanocavities at Pb(111). PHYSICAL REVIEW LETTERS 2016; 117:136803. [PMID: 27715132 DOI: 10.1103/physrevlett.117.136803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Indexed: 06/06/2023]
Abstract
We have studied electron states present at the Pb(111) surface above Ar-filled nanocavities created by ion beam irradiation and annealing. Vertical confinement between the parallel crystal and nanocavity surfaces creates a series of quantum well state subbands. Differential conductance data measured by scanning tunneling spectroscopy contain a characteristic spectroscopic fine structure within the highest occupied subband, revealing additional quantization. Unexpectedly, reflection at the open boundary where the thin Pb film recovers its bulk thickness gives rise to the lateral confinement of electrons.
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Affiliation(s)
- M Müller
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - N Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - S Crampin
- Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - J Kröger
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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48
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Engelund M, Godlewski S, Kolmer M, Zuzak R, Such B, Frederiksen T, Szymonski M, Sánchez-Portal D. The butterfly - a well-defined constant-current topography pattern on Si(001):H and Ge(001):H resulting from current-induced defect fluctuations. Phys Chem Chem Phys 2016; 18:19309-17. [PMID: 27375264 DOI: 10.1039/c6cp04031d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Dangling bond (DB) arrays on Si(001):H and Ge(001):H surfaces can be patterned with atomic precision and they exhibit complex and rich physics making them interesting from both technological and fundamental perspectives. But their complex behavior often makes scanning tunneling microscopy (STM) images difficult to interpret and simulate. Recently it was shown that low-temperature imaging of unoccupied states of an unpassivated dimer on Ge(001):H results in a symmetric butterfly-like STM pattern, despite the fact that the equilibrium dimer configuration is expected to be a bistable, buckled geometry. Here, based on a thorough characterization of the low-bias switching events on Ge(001):H, we propose a new imaging model featuring a dynamical two-state rate equation. On both Si(001):H and Ge(001):H, this model allows us to reproduce the features of the observed symmetric empty-state images which strongly corroborates the idea that the patterns arise due to fast switching events and provides an insight into the relationship between the tunneling current and switching rates. We envision that our new imaging model can be applied to simulate other bistable systems where fluctuations arise from transiently charged electronic states.
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Affiliation(s)
- Mads Engelund
- Centro de Física de Materiales (CFM), CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, 20018, Donostia-San Sebastián, Spain.
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49
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Schenk AK, Tadich A, Sear MJ, Qi D, Wee ATS, Stacey A, Pakes CI. The surface electronic structure of silicon terminated (100) diamond. NANOTECHNOLOGY 2016; 27:275201. [PMID: 27211214 DOI: 10.1088/0957-4484/27/27/275201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A combination of synchrotron-based x-ray spectroscopy and contact potential difference measurements have been used to examine the electronic structure of the (3 × 1) silicon terminated (100) diamond surface under ultra high vacuum conditions. An occupied surface state which sits 1.75 eV below the valence band maximum has been identified, and indications of mid-gap unoccupied surface states have been found. Additionally, the pristine silicon terminated surface is shown to possess a negative electron affinity of -0.86 ± 0.1 eV.
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Affiliation(s)
- A K Schenk
- Department of Chemistry and Physics, La Trobe Institute for Molecular Sciences, La Trobe University, Victoria 3086, Australia
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50
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Kislitsyn DA, Mills JM, Kocevski V, Chiu SK, DeBenedetti WJI, Gervasi CF, Taber BN, Rosenfield AE, Eriksson O, Rusz J, Goforth AM, Nazin GV. Communication: Visualization and spectroscopy of defects induced by dehydrogenation in individual silicon nanocrystals. J Chem Phys 2016; 144:241102. [DOI: 10.1063/1.4954833] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Dmitry A. Kislitsyn
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
| | - Jon M. Mills
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
| | - Vancho Kocevski
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden
| | - Sheng-Kuei Chiu
- Department of Chemistry, Portland State University, Portland, Oregon 97201, USA
| | | | - Christian F. Gervasi
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
| | - Benjamen N. Taber
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
| | - Ariel E. Rosenfield
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
| | - Olle Eriksson
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden
| | - Andrea M. Goforth
- Department of Chemistry, Portland State University, Portland, Oregon 97201, USA
| | - George V. Nazin
- Department of Chemistry and Biochemistry, Materials Science Institute, Oregon Center for Optical, Molecular and Quantum Science, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA
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