Showing papers on "Field electron emission published in 1978"
TL;DR: In this article, the authors derived the universal yield-energy curve of secondary electron emission from insulators from the assumption that the distribution of the secondary electrons due to both incident and back-scattered electrons within the target is isotropic and that it follows the absorption law of Lenard type.
Abstract: The high yield of secondary electron emission from insulators due to electron bombardment may be the result of an increase of the depth of escape. The free-electron scattering theory is applied to the high energy of the primary beam, but it cannot be applied to the low energy of the secondary escaping beam because of the large energy gap of insulators. Then the plasmon loss with the valence electron is considered when the secondary electrons escape. Secondary electron emissions from insulators are calculated from the assumptions that the distribution of the secondary electrons due to both incident and back-scattered electrons within the target is isotropic and that it follows the absorption law of Lenard type. The universal yield-energy curve of secondary electron emission is derived.
106 citations
TL;DR: In this paper, the emission process from W-EuS junction field emitters was studied by combination of several experimental methods: measurement of emission current, spin polarization, energy distribution, and energy-selective spin polarization as function of emitter temperature for different annealing conditions.
Abstract: The emission process from W-EuS junction field emitters was studied by combination of several experimental methods: measurement of emission current, spin polarization, energy distribution, and energy-selective spin polarization as function of emitter temperature for different annealing conditions. The results show that with critical annealing a stoichiometric crystalline EuS layer can be obtained; the interface of such a layer on tungsten acts as a spin filter below the EuS Curie temperature. With emitters annealed at higher temperatures, evidence for electron trapping and the formation of spin clusters has been obtained.
88 citations
TL;DR: In this article, the fine structure in angle-resolved secondary electron spectra is related to the total reflectivity in low-energy electron diffraction (LEED), and theoretical results for tungsten are compared with experimental data.
84 citations
TL;DR: In this paper, field emission into nonpolar liquids was studied for n−hexane, 2,2,4,trimethylpentane, and tetramethylsilane at 275-334 K. The current voltage dependence was found to vary depending on the liquids and the temperature, and was reproduced qualitatively on the basis of the Fowler-Nordheim theory modified by taking account of the space charge effect.
Abstract: Field emission into nonpolar liquids was studied for n‐hexane, 2,2,4‐trimethylpentane, and tetramethylsilane at 275–334 K. The current–voltage dependence was found to vary depending on the liquids and the temperature, and was reproduced qualitatively on the basis of the Fowler–Nordheim theory modified by taking account of the space charge effect. The quasifree electron energy (the electron energy in a liquid with reference to that in vacuum) was estimated from the current–voltage dependence in a space charge‐free region, i.e., from the apparent work functions of the metal emitter (tungsten tip) in the liquids, to be 0, −0.6, and −1.3 eV for n‐hexane (as a standard), trimethylpentane, and tetramethylsilane, at 293 K. These values lie in the same order as determined previously by the photoelectric emission from a metal surface in the liquids, though the dependence on the liquids is more pronounced in the present field emission study.
44 citations
TL;DR: In this article, a periodic electric-field-dependent component in the photo-current from a tungsten field emitter illuminated by the focused beam of a krypton ion laser tuned to a photon energy of 3.51 eV was observed.
37 citations
TL;DR: In this paper, it was shown that atomic resolution in the field electron emission microscope is possible if the tip radius is small enough, which restricts the maximum number of resolvable atoms to about twenty.
30 citations
TL;DR: In this article, a critical analysis of these experiments and their theoretical interpretation is presented, which leads to some observations concerning the current interpretation of itinerant ferromagnetism and possible refinements of the Stoner-Wohl-farth-slater (SWS) band theory to produce better agreement with the ESP sensitive experiments.
20 citations
TL;DR: In this paper, the authors measured the photo field emission (PFE) currents of clean and barium covered tantalum tips with single lines of the mercury arc spectrum and phase-sensitive detection.
17 citations
TL;DR: A review of the recent experimental research confirming the unified theory of electron emission from metals in vacuum, insulators and semiconductors in the whole range between the extreme conditions of field and thermionic emission is presented in this paper.
17 citations
TL;DR: In this article, the authors describe the techniques of spin polarization measurements in field emission and describe the measurement of Kisker et al. on ferromagnetic EuS evaporated on W are discussed along with recent investigations on Ni.
15 citations
TL;DR: In this paper, an atom-probe field ion microscope was used to study the ǫ-111-oriented whiskers of β-SiC, which is a semiconductor of the zinc blende structure, and the distinct difference between the two orientations was found in the field emission patterns of the field evaporated tips.
TL;DR: In this paper, a direct measurement of the tunneling current density, which is found to be in good agreement with free-electron theory for W(110, was reported.
Abstract: The phenomenon of quantum-mechanical tunneling of an electron through a barrier in the potential energy has been well established in a variety of experiments. The quantity which is usually measured in these experiments is the rate of change of tunneling current and not the absolute current density. This paper reports on a direct measurement of the tunneling current density, which is found to be in good agreement with free-electron theory for W(110).
TL;DR: In this article, a field electron emission spectrometer based on a hemispherical analysing element has been designed, built and tested, which has a high sensitivity and a resolution of better than 30 mV.
Abstract: A field electron emission spectrometer based on a hemispherical analysing element has been designed, built and tested. The instrument is versatile and convenient to operate, has a high sensitivity and a resolution of better than 30 mV. The performance of the instrument has been demonstrated in terms of the energy spectra of a tungsten emitter at 300 and 80K, for which comparative theoretical data exist.
TL;DR: In the case of polymers and molecular solids, one further concept is required: the localization of electronic states caused by fluctuations in relaxation energy, which leads to localized molecular ion (or exciton) states rather than extended band states.
Abstract: During the past two decades electron scattering and emission spectroscopies have become utilized almost universally to characterize the properties of solid surfaces. Two major trends have created this situation: The increasing availability of suitable, convenient experimental apparatus, and the recognition and exploitation of those features of electron–solid interactions which render these measurements sensitive to surface properties. Whereas prior Welch Award lectures have dealt with the former trend, the latter is examined herein. Three concepts are central to an understanding of the interaction of ’’low‐energy’’, 10≲E≲103‐eV electrons with the constituents of solids. First, their strong Coulombic interaction with the valence electrons of the solid renders their mean free paths for inelastic collisions of atomic dimensions, i.e., 2≲λ≲20 A. Thus, elastically scattered or emitted electrons in this energy range must have emanated from the uppermost few atomic layers of the solid. Second, the interactions of these electrons with the core electrons are comparable to those with the valence electrons. Therefore, multiple elastic scattering as well as rapid energy loss characterizes their scattering and emission. Third, resonant processes associated with electronic states localized at a surface can be as important as inelastic processes in establishing surface sensitivity. Examples of this phenomenon are found in resonant field emission through adsorbates and resonant photoemission associated with the excitation of transitions characteristic of adsorbed complexes. The major portion of this article is devoted to an indication of how exploitations of these three concepts have led to quantitative surface analysis methodologies for metals and covalent solids. In the case of polymers and molecular solids, however, one further concept is required: the localization of electronic states caused by fluctuations in relaxation energy. These fluctuations lead to localized molecular ion (or exciton) states rather than extended band states. The final portion of this article is devoted to exploring the consequences of this additional concept and how it led to the invention of yet another electron spectroscopy, contact charge exchange spectroscopy, for the examination of molecular ion states in polymers.
TL;DR: The role of localized orbitals and nearly free electrons in the activation of gas molecules by transition metal surfaces is discussed in this paper, where the FIM and FEM evidence for the existence of the localized orbits on metal surfaces and the problem of charge density distribution at the "stepped" surfaces (FEM and FIM tips) are reviewed.
TL;DR: An extractor gauge type electron bombardment ion source using carbon fiber bundles as field electron emitters is described, which makes this ion source a very promising detector for crossed molecular beam scattering experiments.
Abstract: An extractor gauge type electron bombardment ion source using carbon fiber bundles as field electron emitters is described. The cold cathode permits operation of the ionizer within a liquid He cooled cryopump. The high pumping speed for all molecules (except helium) together with its low background pressure make this ion source a very promising detector for crossed molecular beam scattering experiments.
TL;DR: In this article, the authors measured the energy distribution of field emitted electrons by first accelerating them to about 20 keV and then directly energy analyzing these high energy electrons with a high-performance magnetic prism spectrometer.
Abstract: We have measured the energy distribution of field emitted electrons by first accelerating them to about 20 keV and then directly energy analyzing these high energy electrons with a high-performance magnetic prism spectrometer. Our preliminary results indicate that it may be possible to extend the energy range of field emission spectroscopy to more than 5 eV below the Fermi level.
TL;DR: Work function changes produced by gold adsorbed on the (100), (211) and (110) planes of tungsten were studied by field emission microscopy in an attempt to correlate behaviour observed in field emission with that deduced from low energy electron diffraction and reflection high energy electron diffusion studies as discussed by the authors.
TL;DR: In this paper, the binding energy at zero coverage and zero field was determined for the (001, (011) and (112) tungsten planes in the temperature range 80-140 K and in the field range 0.10-0.55 V/A.
TL;DR: In this article, the emission due to free exciton-electron collision has been investigated in relatively high purity n-GaAs under the external electric field, and the emission peak shifts to lower energy while the higher energy side of the peak broadens.
TL;DR: In this paper, the possibility of obtaining some information about the current density of field emission drawn from ultra sharp field emitters in using Fowler-Nordheim plots is considered, and it is shown that the present density obtained from experimental FN plots is the lower bound of an unknown true value of current density.
TL;DR: In this paper, the authors measured the field electron emission from a 10-μm tungsten filament at an environmental pressure of ∠1×10−8 Torr (1.33× 10−6 Pa).
Abstract: Characteristics of field electron emission from the dense array of microneedles of tungsten prepared on a 10‐μm tungsten filament were measured at an environmental pressure of ∠1×10−8 Torr (1.33×10−6 Pa). Electron emission was not uniform over the filament surface, but the variation of emission current with applied voltage explicitly obeyed the Fowler–Nordheim relationship. At an emission current of ∠10−4 A, a vacuum arc was induced that led to a permanent change in current–voltage characteristic. Current fluctuation was dependent on emitter temperature and applied voltage, and the lowest fluctuation of about 4% was routinely obtained at ∠550 K and at applied voltages several percent lower than the arc‐inducing voltage. Macroscopic current density amounted to ∠20–80 mA/cm2 at the best stability.
TL;DR: In this article, a 135° electrostatic spherical deflection analyzer was used to investigate the total energy distribution (TED) of field emitted electrons from the (0001 and (0001) planes of field evaporated zinc oxide tips.
TL;DR: A brief review of the principal applications of field emission techniques to chemisorption on metals is presented in this article, which includes work function measurements on single crystal planes, adsorbate diffusion, including diffusion on single planes, measurements of desorption rates and activation energies, field emission distributions, and finally the use of field emitters as sensitive detectors in DESORption and reflection measurements.
TL;DR: In this paper, the photoelectric emission from a pure or barium-coated single crystal tungsten tip submitted to a high electric field was studied under illumination by light of energy smaller than the work fonction of the substrate.
TL;DR: In this article, the changes produced by an external magnetic field on field emission currents from tungsten needles held at helium temperatures were investigated and a steady decrease with field above a critical field was reported together with oscillatory variations of the order of 10 - 15%.
Patent•
11 May 1978
TL;DR: In this article, the authors proposed to obtain the carbon chip which is highly stable, by adhering carbon coating on the metallic chip with vaccum evaporation, which can be used to obtain high stability.
Abstract: PURPOSE:To obtain the carbon chip which is highly stable, by adhering carbon coating on the metallic chip with vaccum evaporation.
TL;DR: In this paper, a method for etching field emission tips from Pb-Si-Cu metallic glass wires is described, and the field electron emission from these tips is sufficiently stable in the 10-9 Torr region.
Abstract: A method for etching field emission tips from Pb-Si-Cu metallic glass wires is described. The field electron emission from these tips is sufficiently stable in the 10-9 Torr region. The emission is confined to a cone of half-angle 0.15 rad for a total emission current of about 5 mu A.