Showing papers on "Field electron emission published in 1980"
TL;DR: In this article, a simple model is proposed to explain how a breakdown avalanche of secondary emission electrons can lead to surface flashover when an insulator in vacuum breaks down a few nanoseconds after high voltage is applied.
Abstract: A simple model is proposed to explain how a breakdown avalanche of secondary emission electrons can lead to surface flashover when an insulator in vacuum breaks down a few nanoseconds after high voltage is applied. The case of a plane insulator–vacuum interface perpendicular to parallel electrodes is considered. Positive surface charging is assumed to occur almost immediately upon application of the voltage, and the attendent secondary emission avalanche is assumed to be maintained at saturation throughout the prebreakdown time delay by field emission from the cathode electrode. Bombardment of the insulator by avalanche electrons desorbs a cloud of gas, which is partially ionized as it drifts through the swarm of electrons in the avalanche. The electric field at the cathode end of the insulator becomes enhanced as positive ions accumulate, which in turn increases the field emission and the rates of gas desorption and ionization. This and other regenerative processes rapidly lead to breakdown. Field enhanc...
380 citations
242 citations
TL;DR: In this article, the authors report the observation of highly polarized, angle-tunable visible light emission from Al-AlOx-Ag tunnel junctions fabricated on holographic gratings.
Abstract: We report the observation of highly polarized, angle‐tunable visible light emission from Al‐AlOx‐Ag tunnel junctions fabricated on holographic gratings. From the angular dependence of the emission frequency we identify the electromagnetic mode responsible for the emission. The mode is surface plasmonlike with a dispersion that closely follows the light line. This is in contrast to the much lower phase velocity ’’junction’’ mode believed responsible for the light emission on surface‐roughened tunnel junctions. We argue that both modes should be considered in describing the emission from these devices.
57 citations
TL;DR: In this article, the authors discuss the emission of positive ions from liquid metals under the action of high electric fields and the basic principles of such sources are discussed and the design and experimental behaviour of a gallium source are described in detail.
Abstract: Discusses the emission of positive ions from liquid metals under the action of high electric fields. High brightness sources are being developed with a variety of applications in mind. The basic principles of such sources are discussed and the design and experimental behaviour of a gallium source are described in detail. Measurements of the current-voltage characteristics of the source, together with the angular distribution of the beam are presented. The current-voltage behaviour is found to be in agreement with the predictions of a simple space charge model. Field ion creation mechanisms require liquid metal emitting features of submicron dimensions and this does not appear to be consistent with space-charge considerations and the best available microscopic observations. This apparent paradox can be resolved if a highly mobile emitting feature is assumed to exist.
39 citations
TL;DR: In this article, a mixture of polyethylene oxide and water was applied to smooth wire cathodes to demonstrate ionization by [CI]− ion attachment with the examples of 20-hydroxycholesterol and sucrose.
Abstract: Field desorption of negative ions can be achieved below the threshold of field electron emission. To this end a mixture of the sample with polyethylene oxide and water was applied to smooth wire cathodes. The mass spectra of some inorganic and organic compounds are reported. Anionization by [CI]− ion attachment is demonstrated with the examples of 20-hydroxycholesterol and sucrose.
38 citations
TL;DR: In this paper, the temperature rise of a tungsten field emitter illuminated by the focused beam of a laser operating at a range of wavelengths in the visible region of the spectrum was determined as a function of the displacement of the focused spot of light along the shank.
Abstract: Thermal field emission of electrons has been investigated from a tungsten field emitter illuminated by the focused beam of a laser operating at a range of wavelengths in the visible region of the spectrum. The temperature rise of the tip is determined as a function of the displacement of the focused spot of light along the shank, and of its polarization. The experimental data are compared with the results of a first‐principle calculation of the temperature rise, based on an experimental investigation of the intensity distribution within the focused spot of light and of the geometry of the field emitter. The comparison shows that when the laser beam is focused close to the tip the temperature rise is anomalously large; evidence is presented which suggests that the temperature rise of the tip is substantially enhanced by diffraction effects.
36 citations
TL;DR: In this paper, a new empirical field calibration equation is presented, which is obtained from a detailed numerical study of the field distribution within a real field ion microscope, separating the important shank angle effect from other geometric influences.
Abstract: A new empirical field calibration equation is presented. This relationship is obtained from a detailed numerical study of the field distribution within a real field ion microscope. The equation separates the important shank angle effect from the other geometric influences. Comparison is made of the predicted field with actual values.
30 citations
TL;DR: In this article, secondary electron emission (SEE) measurernent was used to investigate the conduction band structures of polyethylene, and ultraviolct photoelectron spectra.
Abstract: Secondary electron emission (SEE) measurernent was used to investigate the conduction band structures of n-C 28 H 58 , n-C 36 H 74 , n-C 44 H 90 and polyethylene, and ultraviolct photoelectron spectra of n-C 28 H 58 and n-C 36 H 74 were measured. Several structures, whose kinetic energy positions were independent of the energies of incident sources, were observed in the both spectra. It was found that SEE spectra of all compounds were almost similar with each other, and corresponded well with the photoelectron spectra. These structures are ascribed to the high density-of-states parts of the conduction band which do not depend on the chain length. The spectra were compared with the energy distribution curve of secondary electrons estimated by the use of XPS result for the valence band and theoretical result for the conduction band of isolated chain. The energy positions of the structures of the estimated curve agree fairly well with those of observed spectrum.
24 citations
TL;DR: In this paper, a simple model is presented in which the secondary electron emission coefficient of different materials is calculated as a function of the energy and angle of incidence of the primary electrons, and the model provides a simple calculation method to take into account the important differences between various materials.
23 citations
TL;DR: In this article, metal whiskers were found to grow on the electron-emitting region of a pointed field cathode when it was operated in a vacuum containing metal carbonyl vapors.
Abstract: Metallic whisker crystals were found to grow on the electron‐emitting region of a pointed field cathode when it was operated in a vacuum containing metal carbonyl vapors. Metal ions are produced by collisions of carbonyl molecules with field electrons and the rapid growth of the whiskers is controlled by the supply of metal ions to the electron‐emitting area. The crystals are basically monocrystalline, and the evidence obtained indicates that they do not contain an axial screw dislocation emerging at their growing tip.
21 citations
TL;DR: In this article, a simple model is presented to account for the correlation effect on the binding energy of the surface electrons, and the measured escape rate at higher electron densities explicitly demonstrates the electron correlation effect.
Abstract: Electron escape from the two-dimensional surface state is studied for liquid 4He and 3He surfaces. Experimental conditions are established under which “proper” signals are obtained to give the intrinsic escape rates. The escape rates in the temperature range 1.1 > T > 0.9 K for the 4He surface and 0.6 > T > 0.44 K for the 3He surface show the theoretically expected thermalactivation-type temperature dependence. In the present experimental configuration, the measured escape rate at higher electron densities explicitly demonstrates the electron correlation effect. A simple model is presented to account for the correlation effect on the binding energy of the surface electrons.
TL;DR: In this article, negative ions can be generated by a field ionization process at field strengths below the onset field strength for field electron emission, and a theoretical discussion of the conditions required for the occurrence of such a process is given.
TL;DR: In this paper, the field dependence of the difference in standarized energy between helium ions produced from the field-adsorbed position and from the critical surface has been interpreted in terms of field penetration into jellium surface.
Abstract: The field dependence of the difference in standarized energy between helium ions produced from the field‐adsorbed position and from the critical surface has recently been interpreted in terms of field penetration into a jellium surface. A model that takes the atomic structure of the real surface into account interprets these results in terms of the proper polarizability of emitter surface atoms. Values obtained for tungsten are 2.01 and 2.07 meV V−2 nm2.
TL;DR: In this article, the photo field emission currentvoltage characteristics show various slopes and shoulders, and these shoulders are considered as correlated with optical transitions between energy bands of tungsten, and the final and initial energies are evaluated from the excitation energy and the known lowering of the barrier maximum.
TL;DR: In this article, a field emission cold cathode with a lifetime in excess of a thousand hours has been proposed for tungsten needle or refractory metal carbide types such as Ta, V and Nb.
TL;DR: In this article, the dependence of the breakdown voltage and the pre-breakdown current on the crossed electrical and magnetic fields in vacuum was investigated and compared with the theory of the magnetic perturbation of the field emission from protrusions covered with semiconducting oxide layers.
Abstract: An experimental study is presented for the dependence of the breakdown voltage and the prebreakdown current on the crossed electrical and magnetic fields in vacuum. The magnetic field is varied in the range 0–250 G and the gap separation 0.5–3 cm. Bruce profiled copper electrodes which have been prebaked either in vacuum or hydrogen were employed. The breakdown voltage and the prebreakdown current are presented as functions of the magnetic flux density at fixed gap separation as well as at fixed flux density as functions of the gap separation. Comparison is made between these functions and curves calculated from the theory of the magnetic perturbation of the field emission from protrusions covered with semiconducting oxide layers and good agreement is obtained.
TL;DR: In this article, the influence of the quantum size effect (QSE) in very thin Pd and Au films (0.5
Abstract: The influence of the quantum size effect (QSE) in very thin Pd and Au films (0.5
TL;DR: In this article, the authors used an optical multichannel analyzer with a resolution of 1.3 A over the range 1850-6500 A. The dominant emission is due to GaI radiation and is likely due to the two-body collision between atomic gallium and electrons.
Abstract: When gallium is ionized on the cap of a field emitter, the optical emission emerges from right at the cap of the emitter. This optical emission was spectroscopically studied using an optical multichannel analyzer with a resolution of 1.3 A over the range 1850–6500 A.The dominant emission is due to Ga I radiation and is likely due to the two‐body collision between atomic gallium and electrons.
01 Jan 1980
TL;DR: In this paper, the development of thought concerning electrical breakdown in vacuum with particular regard to field emission, interaction of cathode emission at the anode, and particle effects, including impurities, is reviewed in two parts.
Abstract: In this paper vacuum breakdown phenomena are reviewed in two parts. The first considers the development of thought concerning electrical breakdown in vacuum with particular regard to field emission, interaction of cathode emission at the anode, and particle effects, including impurities. While Section 1 is basically historical, Section 2 considers these and other topics in the light of recent literature.
TL;DR: Foil and foilless field emission diodes are used in free-electron Raman lasers with the view of reducing the perpendicular energy of the emitted beam as discussed by the authors, which leads to a significant reduction in radiated intensity, indicating an overall improvement in beam quality.
Abstract: Foil and foil‐less field emission diodes (current ∼10 kA, voltage ∼1.5 MV) used in free‐electron Raman lasers are studied experimentally with the view of reducing the perpendicular energy of the emitted beam. Microwave emission, attributed to a cyclotron instability in the beam, is used as the diagnostic. Removal of the outer portions of the beam leads to a significant reduction in the radiated intensity, indicating an overall improvement in beam quality.
TL;DR: In this paper, a technique is proposed which enables one to fabricate multi-point field emission sources of bakeable structure based on the cathodic growth of metallic needle crystal from metal crabonyl vapors.
Abstract: A technique is proposed which enables one to fabricate multi‐point field emission sources of bakeable structure. The technique is based on the cathodic growth of metallic needle crystal from metal crabonyl vapors and has so far been confirmed to provide emission sources of W, Mo, and Mo2C. The field emission sources prepared by this technique are highly resistive to thermal treatment and actually yield field ions possessing satisfactory intensities when used as the ion sources of a field ion mass spectrometer. It is believed that the application of these field emission sources is not restricted to mass spectrometry but can be extended to other ion and electron optical systems. The technique may thus open new areas in field emission technology.
TL;DR: In this article, the field emission characteristics from heated tungsten emitter were experimentally investigated in several ambient gases and the emission current was stabilized by heat treatment at about 900°C in CH 4.
TL;DR: In this article, the effects of tunnelling and field emission across very narrow gaps in the gold film were considered, and an alternative scheme was suggested which considered the effect of field emission on the gold films.
Abstract: Non-ohmic characteristics, negative resistance and electron emission has been observed arising from thin Al-Au couples and thin films of gold which contain small gaps. These characteristics are remarkably similar to those observed from sandwich MIM structures showing a break point at about 4 V in the I-V curve followed by negative resistance and electron emission. These effects, coupled with reversible negative resistance behaviour, pressure sensitivity and electron emission cannot be adequately described by a filamentary model alone. An alternative scheme is suggested which considers the effects of tunnelling and field emission across very narrow gaps in the gold film.
01 Jan 1980
TL;DR: In this paper, it was shown that the energy relaxation is governed by an interplay of electron-electron scattering and optical phonon emission in III-V semi-conductors.
Abstract: Electrically excited cyclotron emission has been observed in several semiconductors (InSb, GaAs, CdHgTe and Si-inversion layers). Maximum output powers of 1 μW are chieved for n-GaAs and n-InSb sources in the parallel field (E ‖ B) configuration. Emission linewidths are found to be between 1 cm−1 and 2 cm−1 for the purest samples available determined by ionized impurity scattering. Investigations of the electric field dependence have shown that the observed intensities are well described with hot electron distribution functions. The energy relaxation is governed by an interplay of electron-electron scattering and optical phonon emission in III–V semi-conductors. Electron-electron scattering is also responsible for the electronic lifetime in the 1.Landau level giving values of 10-9 sec for excited electron densities of 1012cm−3. Applications of Landau emission sources are shown in spectroscopy and testing of fast detectors.
TL;DR: In this article, the growth process of potassium epitaxial layers deposited from the vapour onto a tungsten tip surface was investigated using the field emission technique. And the results were discussed taking into account the transport mechanism and the high anisotropy of the surface structure.
TL;DR: In this article, a field emission microscope (FEM) was used to examine the surface defects produced by argon ion bombardment and the elimination of this damage by thermal annealing to elucidate the structure of active sites of a platinum catalyst for hydrogenation of acetylene.
TL;DR: In this paper, the authors used field electron emission microscopy to study the adsorption of water on platinum and its production by the reaction of hydrogen with adsorbed oxygen.
TL;DR: In this paper, the authors used field-emission microscopy (FEM) to study the adsorption and thermal decomposition of CH3OH on W. The results confirm the proposal that adsorbed HCHO is one of the reaction intermediates in the catalytic decomposition.
Abstract: Field-emission microscopy (FEM) has been used to study the adsorption and thermal decomposition of CH3OH on W. At room temperature, the dosage of CH3OH has remarkable control of the shift in average work function, ϕ. Small doses cause an increase in ϕ while heavy doses cause a decrease, suggesting negatively or positively charged adsorption intermediates, respectively. In the latter case, in comparison with HCHO on W, heat treatment above ≈ 650 K causes similar changes in emission pattern and average work function. These results confirm the proposal that adsorbed HCHO is one of the reaction intermediates in the catalytic decomposition of CH3OH on W.