Chapter Two <Fiecd~ Emission Theory 2 FIELD EMISSION
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Field Electron Emission Characteristic of Graphene
Field electron emission characteristic of graphene Weiliang Wang, Xizhou Qin, Ningsheng Xu, and Zhibing Li* State Key Lab of Optoelectronic Materials and Technologies, and School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, People’s Republic of China Abstract The field electron emission current from graphene is calculated analytically on a semiclassical model. The unique electronic energy band structure of graphene and the field penetration in the edge from which the electrons emit have been taken into account. The relation between the effective vacuum barrier height and the applied field is obtained. The calculated slope of the Fowler-Nordheim plot of the current-field characteristic is in consistent with existing experiments. Keywords: field electron emission, graphene, field penetration PACS: 73.22.Pr, 79.70.+q 1. Introduction The cold field electron emission (CFE) as a practical microelectronic vacuum electron source , that is driven by electric fields of about ten volts per micrometer or less, has been demonstrated by the Spindt-type cathodes, which is basically micro-fabricated molybdenum tips in gated configuration [1] . In recent years, much interest has turned to the nano-structures, such as the carbon nanotubes and nanowires of various materials [2, 3], for that the high aspect ratios of these materials naturally lead to high field enhancement at the tips of the emitters thereby lower the threshold of macroscopic fields for significant emission. So far, most of the experimental efforts and theoretical studies on the possible applications and the physical mechanism of CFE have been concentrated on the quasi one-dimensional structures, such as carbon nanotubes and various nanowires. -
Surface Plasmons and Field Electron Emission in Metal Nanostructures
Surface Plasmons and Field Electron Emission In Metal Nanostructures N. Garcia1 and Bai Ming2 1. Laboratorio de Física de Sistemas Pequeños y Nanotecnología, Consejo Superior de Investigaciones Científicas, Serrano 144, Madrid 28006 (Spain) and Laboratório de Filmes Finos e Superfícies, Departamento de Física, Universidade Federal de Santa Catarina, Caixa Postal 476, 88.040-900, Florianópolis, SC, (Brazil) 2. Electromagnetics laboratory, School of Electronic Information Engineering, Beijing University of Aeronautics and Astronautics, Beijing, 100191 (China) Abstract In this paper we discuss the field enhancement due to surface plasmons resonances of metallic nanostructures, in particular nano spheres on top of a metal, and find maximum field enhancement of the order of 102, intensities enhancement of the order of 104. Naturally these fields can produce temporal fields of the order of 0.5V/Å that yield field emission of electrons. Although the fields enhancements we calculated are factor of 10 smaller than those reported in recent experiments, our results explain very well the experimental data. Very large atomic fields destabilize the system completely emitting ions, at least for static field, and produce electric breakdown. In any case, we prove that the data are striking and can solve problems in providing stabilized current of static fields for which future experiments should be done for obtaining pulsed beams of electrons. PACS numbers: 79.70.+q, 36.40.Gk, 79.60.-i Electrons are emitted from surfaces due to the photoelectron effect when the light energy that illuminates the surface is larger than its work function. But also more interesting with the development of pulsed lasers are the multiphoton processes[1,2]. -
New Thermal Field Electron Emission Energy Conversion Method VE Ptitsin
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Electronic Sumy State University Institutional Repository PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 1 No 4, 04NEA03(4pp) (2012) New Thermal Field Electron Emission Energy Conversion Method V.E. Ptitsin* Institute for Analytical Instrumentation of the Russian Academy of Sciences, 26, Rizhsky Pr., 190103 St. Petersburg, Russia New thermal field electron emission energy conversion method for vacuum electron-optical systems (EOS) with a nanostructured surface electron sources is offered and developed. Physical and numerical modeling of an electron emission and transport processes for different EOS is carried out. It is shown that at the specific configuration of electrostatic and magnetic fields in the EOS offered method permits to realize energy conversion processes with high efficiency. Keywords: Energy conversion, Thermal field electron emission, Nanostructures. PACS numbers: 84.60. – h, 79.70. + q, 85.45.Db 1. INTRODUCTION (less 50 V/μm), some NS (ZrO2/W and ZrO2/Mo) at temperatures of substance NS ≈ 1900 K possess an Achievements of last decades in area of micro-and abnormally high reduced brightness (to 106 A/(cm2 nanotechnology promoted revival of scientific interest sr V)) and high stability of thermal field emission to a problem of direct transformation of thermal and properties. The found out (in specified above physical light energy to electric energy. As a result of conditions) phenomenon of sharp increase NS emission development of nanotechnology methods researchers ability has been named by "abnormal thermal field had new possibilities for use in the workings out of the emission” (ATFE). -
Electron Emission from 2 Dimensional Structures
Analytical treatment of cold field electron emission from a nanowall emitter XIZHOU QIN, WEILIANG WANG, NINGSHENG XU, ZHIBING LI* State Key Laboratory of Optoelectronic Materials and Technologies School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, P.R. China RICHARD G. FORBES Advanced Technology Institute, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom This paper presents an elementary, approximate analytical treatment of cold field electron emission (CFE) from a classical nanowall (i.e., a blade-like conducting structure situated on a flat conducting surface). A simple model is used to bring out some of the basic physics of a class of field emitter where quantum confinement effects exist transverse to the emitting direction. A high-level methodology is presented for developing CFE equations more general than the usual Fowler-Nordheim-type (FN-type) equations, and is applied to the classical nanowall. If the nanowall is sufficiently thin, then significant transverse-energy quantization effects occur, and affect the overall form of theoretical CFE equations; also, the tunnelling barrier shape exhibits "fall-off" in the local field value with distance from the surface. A conformal transformation technique is used to derive an 1 analytical expression for the on-axis tunnelling probability. These linked effects cause complexity in the emission physics, and cause the emission to conform (approximately) to detailed regime-dependent equations that differ -
Surface Vs Bulk Electronic Structures of a Moderately Correlated
Surface vs bulk electronic structures of a moderately correlated topological insulator YbB6 revealed by ARPES N. Xu,1* C. E. Matt,1,2 E. Pomjakushina,3 J. H. Dil,4,1 G. Landolt, 1,5 J.-Z. Ma,1,6 X. Shi,1,6 R. S. Dhaka,1,4,7 N. C. Plumb,1 M. Radović,1,8 V. N. Strocov, 1 T. K. Kim,9 M. Hoesch, 9 K. Conder,3 J. Mesot,1,2,4 H. Ding,6, 10 and M. Shi1,† 1Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland 2Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland 3Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland 4Institute of Condensed Matter Physics, Ecole Polytechnique Fedé ralé de Lausanne, CH-1015 Lausanne, Switzerland 5Physik-Institut, Universität Zürich, Winterthurerstrauss 190, CH-8057 Zürich, Switzerland 6Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China 7Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110016, India 8 SwissFEL, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland 9Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK, 10 Collaborative Innovation Center of Quantum Matter, Beijing, China Page: 1 Systematic angle-resolved photoemission spectroscopy (ARPES) experiments have been carried out to investigate the bulk and (100) surface electronic structures of a topological mixed-valence insulator candidate, YbB6. The bulk states of YbB6 were probed with bulk-sensitive soft X-ray ARPES, which show strong three-dimensionality as required by cubic symmetry. -
Surface and Quantum-Well States in Ultra Thin Pt Films on the Au(111) Surface
materials Article Formation of Surface and Quantum-Well States in Ultra Thin Pt Films on the Au(111) Surface Igor V. Silkin 1,*, Yury M. Koroteev 1,2,3, Pedro M. Echenique 4,5 and Evgueni V. Chulkov 3,4,5 1 Department of Physics, Tomsk State University, 634050 Tomsk, Russia; [email protected] 2 Institute of Strength Physics and Materials Science, Siberian Branch, Russian Academy of Sciences, 634050 Tomsk, Russia 3 Department of Physics, Saint Petersburg State University, 198504 Saint Petersburg, Russia 4 Donostia International Physics Center (DIPC), 20018 San Sebastian/Donostia, Basque Country, Spain; [email protected] (P.M.E.); [email protected] (E.V.C.) 5 Department of Materials Physics, Materials Physics Center CFM-MPC and Mixed Center CSIC-UPV, 20080 San Sebastian/Donostia, Basque Country, Spain * Correspondence: igor [email protected]; Tel.: +34-943-01-8284 Received: 21 November 2017; Accepted: 7 December 2017; Published: 9 December 2017 Abstract: The electronic structure of the Pt/Au(111) heterostructures with a number of Pt monolayers n ranging from one to three is studied in the density-functional-theory framework. The calculations demonstrate that the deposition of the Pt atomic thin films on gold substrate results in strong modifications of the electronic structure at the surface. In particular, the Au(111) s-p-type Shockley surface state becomes completely unoccupied at deposition of any number of Pt monolayers. The Pt adlayer generates numerous quantum-well states in various energy gaps of Au(111) with strong spatial confinement at the surface. As a result, strong enhancement in the local density of state at the surface Pt atomic layer in comparison with clean Pt surface is obtained. -
Field Emission Cathodes to Form an Electron Beam Prepared from Carbon Nanotube Suspensions
micromachines Review Field Emission Cathodes to Form an Electron Beam Prepared from Carbon Nanotube Suspensions Karolina Urszula Laszczyk Wroclaw University of Science and Technology, Faculty of Microsystem Electronics and Photonics, 53-633 Wroclaw, Poland; [email protected] Received: 3 February 2020; Accepted: 24 February 2020; Published: 29 February 2020 Abstract: In the first decade of our century, carbon nanotubes (CNTs) became a wonderful emitting material for field-emission (FE) of electrons. The carbon nanotube field-emission (CNT-FE) cathodes showed the possibility of low threshold voltage, therefore low power operation, together with a long lifetime, high brightness, and coherent beams of electrons. Thanks to this, CNT-FE cathodes have come ahead of increasing demand for novel self-sustaining and miniaturized devices performing as X-ray tubes, X-ray spectrometers, and electron microscopes, which possess low weight and might work without the need of the specialized equipped room, e.g., in a harsh environment and inaccessible-so-far areas. In this review, the author discusses the current state of CNT-FE cathode research using CNT suspensions. Included in this review are the basics of cathode operation, an evaluation, and fabrication techniques. The cathodes are compared based on performance and correlated issues. The author includes the advancement in field-emission enhancement by postprocess treatments, incorporation of fillers, and the use of film coatings with lower work functions than that of CNTs. Each approach is discussed in the context of the CNT-FE cathode operating factors. Finally, we discuss the issues and perspectives of the CNT-FE cathode research and development. -
Theory and Modeling of Field Electron Emission from Low-Dimensional
Theory and Modeling of Field Electron Emission from Low-Dimensional Electron Systems by Alex Andrew Patterson B.S., Electrical Engineering University of Pittsburgh, 2011 M.S., Electrical Engineering Massachusetts Institute of Technology, 2013 Submitted to the Department of Electrical Engineering and Computer Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Electrical Engineering at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY February 2018 c Massachusetts Institute of Technology 2018. All rights reserved. Author.............................................................. Department of Electrical Engineering and Computer Science January 31, 2018 Certified by. Akintunde I. Akinwande Professor of Electrical Engineering and Computer Science Thesis Supervisor Accepted by . Leslie A. Kolodziejski Professor of Electrical Engineering and Computer Science Chair, Department Committee on Graduate Theses 2 Theory and Modeling of Field Electron Emission from Low-Dimensional Electron Systems by Alex Andrew Patterson Submitted to the Department of Electrical Engineering and Computer Science on January 31, 2018, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Electrical Engineering Abstract While experimentalists have succeeded in fabricating nanoscale field electron emit- ters in a variety of geometries and materials for use as electron sources in vacuum nanoelectronic devices, theory and modeling of field electron emission have not kept pace. Treatments of field emission which address individual deviations of real emitter properties from conventional Fowler-Nordheim (FN) theory, such as emission from semiconductors, highly-curved surfaces, or low-dimensional systems, have been de- veloped, but none have sought to treat these properties coherently within a single framework. As a result, the work in this thesis develops a multidimensional, semi- classical framework for field emission, from which models for field emitters of any dimensionality, geometry, and material can be derived. -
Field-Emission Properties in the ERL-Electron Source
Field-Emission Properties in the ERL-Electron Source Vaibhav Kukreja Department of Physics, Cornell University, Ithaca, New York, 14853 (Dated: August 10, 2005) One concern around the development of the electron gun for the next generation linear accelerator, namely ERL (Energy Recovery Linac), is finding a suitable mate- rial and surface preparation technique to construct the cathode of the electron gun. With the hope to run the electron gun at an electrostatic field of 15 MV/m (750 kV over a 5 cm gap), electron field emission poses many risks to the function and the structure of the gun. We have tested five electrodes with different composition and surface treatment. In this paper, we will discuss their emission behavior, and briefly introduce and apply the Fowler-Nordheim field emission theory to determine the enhancement factors and emission areas for the examined samples. The Bare Titanium sample has shown dramatic results with no field emission up 21 MV/m. This might be a strong candidate for the material composition of the cathode. I. INTRODUCTION Electron field emission imposes a great restriction on the operating voltage of electron guns. In recent years, there has been an appeal to construct DC electron guns based on photoemission cathodes and use cathode fields that are significantly higher than what today's guns operate at (well below 10 MV/m). The motivation for having electron sources with such high field strengths is primarily based on the hope that they can yield high brightness and high average current beams [3]. These features are very important for the energy recovered superconducting linear accelerators such as the ERL and for future applications in light sources, electron cooling and electron-ion colliders. -
Field Electron Emission Mechanism in an Ultrathin Multilayer Planar Cold
Field electron emission mechanism in an ultrathin multilayer planar cold cathode Ru-Zhi Wang1* Hui Yan1* Bo Wang1 Xing-Wang Zhang2 Xiao-Yuan Hou3 1 Laboratory of Thin Film Materials, Beijing University of Technology, Beijing 100022, China 2Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083, China 3Surface Physics Laboratory (National Key Laboratory), Fudan University, Shanghai 200433, China Field electron emission from an ultrathin multilayer planar cold cathode (UMPC) including quantum well structure has been both experimentally and theoretically investigated. We found that only tuning the energy levels of UMPC the field electron emission (FE) characteristic can be evidently improved, which is unexplained by the conventional FE mechanism. Field electron emission mechanism dependent on the quantum structure effect, which supplies a favorable location of electron emission and enhances tunneling ability, has been presented to expound the notable amelioration. An approximate formula brought forward can predict the quantum FE enhancement, which the theoretical prediction is close to the experimental result. PACS codes: 79.70.+q; 73.40.Gk; 73.20.At; 02.60.-x; FE current is unstable and may lead to a I. Introduction vacuum breakdown [2]. People tend to The cold cathodes have been attracted consider the planar cold cathodes more and more attentions for its constructed by some wide band-gap important applications in flat-panel semiconductor (WBGS) films [3], which display and some power amplifier [1]. owes to its simple fabrication, easy However, the present cold cathodes do integration, convenient control, and stable emission et al. Nevertheless, its FE not have so good performance that it can be considered as a commercial current density is not high enough and/or application on a large scale. -
Surface States
Theoretical Surface Science 1. Introduction Wintersemester 2007/08 Surfaces Theoretical approach Axel Groß Processes on surfaces play an enormous- Some decades ago: phenomenological • • Universit ¨at Ulm, D-89069 Ulm, Germany ly important technological role thermodynamic approach prevalent http://www.uni-ulm.de/theochem Harmful processes: Nowadays: microscopic approach Outline • • 1. Rust, corrosion 1. Introduction 2. Wear Theoretical surface science no longer li- • mited to explanatory purposes 2. The Hamiltonian 3. Electronic Structure Methods and Total Energies Advantageous processes: • Many surface processes can indeed be 4. Approximate Interatomic Potentials 1. Production of chemicals • described from first pricinples, i.e., with- 5. Dynamics of Processes on Surfaces 2. Conversion of hazardous waste out invoking any empirical parameter 6. Kinetic Modelling of Processes on Surfaces Here: microscopic perspective of theoretical surface science 7. Electronically non-adiabatic Processes Experiment: a wealth of microscopic information available: 8. Outlook STM, REMPI, QLEED, HREELS, . Surface and image potential states Cu(111) surface states Cu(111) DFT surface band structure Cu(100): Image potential states Don Eigler, IBM Almaden 5 Quantum Corral Quantum Mirage 8 ε n=1 0 F n=2 6 n=3 ε vac 4 Energy (eV) Image potential Energy (eV) −5 V(z)=−e2 /4z 2 ε F 48 Fe atoms on Cu(111) placed in a circle Elliptival Quantum Corral with a Co atom −10 20 40 with diameter 71 A˚ Distance from the surface z(Å) at the focus of the ellipse Σ Γ Σ M.F. Crommie et al. , Science 262 , 218 (1993). M M H.C. Manoharan et al. , Nature 403 , 512 (2000). -
Surface Electronic Structure
Home Search Collections Journals About Contact us My IOPscience Surface electronic structure This content has been downloaded from IOPscience. Please scroll down to see the full text. 1982 Rep. Prog. Phys. 45 223 (http://iopscience.iop.org/0034-4885/45/3/001) View the table of contents for this issue, or go to the journal homepage for more Download details: IP Address: 152.17.136.208 This content was downloaded on 10/04/2015 at 02:48 Please note that terms and conditions apply. Rep. Prog. Phys., Vol. 45, 1982. Printed in Great Britain Surface electronic structure J E Inglesfield Science and Engineering Research Council, Daresbury Laboratory, Daresbury, Warrington WA4 4AD, UK Abstract The theory of the electronic structure of clean metal and semiconductor surfaces is reviewed, starting from an effective one-electron Schrodinger equation. Methods for solving the Schrodinger equation at surfaces are briefly described, and the effects of the surface on the electronic wavefunctions are discussed using simple models. The results of detailed calculations of the surface electronic structure of s-p bonded metals, transition metals and semiconductors are reviewed, with an emphasis on the effect of the local environment on the density of states. Properties like the work function and surface energy depend on the surface electronic structure, and their variation with material and surface is discussed; the surface energy contains an important contribution from the interaction between electrons, and this will be considered in some detail. The change in electronic structure compared with the bulk leads to changes in atomic structure, with surface reconstruction on semiconductor and some metal surfaces, and this is also discussed.