Emission from ferroelectric cathodes. Revision 1

Sampayan, S.; Caporaso, G.J.; Holmes, C.; Lauer, E.J.; Prosnitz, D.; Trimble, D.; Westenskow, G.

doi:10.2172/10124125

Cited by 10 publications

(32 citation statements)

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“…[14][15][16][17][18][19][20][21][22], initiates P s -switching at the same threshold field level. However, the sequence of processes following the switching, including plasma formation and electron extraction by external field, may widely differ from the FE self-emission described above.…”

Section: Electric-field-excited Fe Electron Emissionmentioning

confidence: 99%

“…The strong electrically-induced emission from FE samples covered with metallic grid electrodes is very efficient, but weak FE emission has also been observed from a bare FE surface without any electrode or conducting material (for example, [3,5,26]). The latter type of electron emission cannot be induced with any of the alternative emission methods [14][15][16][17][18][19][20][21][22] using reverse field excitation, which rely on the field emission of electrons from the FE-metal interfaces of the GE grid electrode [27].…”

Section: Electric-field-excited Fe Electron Emissionmentioning

confidence: 99%

“…In Refs. [12][13][14][15][16][17][18][19] PZT material with a Zr/Ti composition around 52/48, produced industrially for piezoelectric applications, has been used often for emission experiments with reverse field direction. Industrially available materials of this type are mostly doped with a few percent of Nb or Nd.…”

Section: 1 Fe Materials and Cathode Dimensionsmentioning

confidence: 99%

“…If the electrical contact between the metallic grid electrodes and the bare FE surface is not quasi-perfect, FE emission cannot be excited, even with the best FE material. Other types of electron emission from FE remain not only feasible with non-ideally adhering electrodes, but may even be enhanced as is the case with reverse-field excitation [14][15][16][17][18][19][20][21] or with excitation by metal-dielectric interface breakdown [22]. The interface between electrode metal layer and the FE surface characterized by a finite roughness determines the average threshold voltage needed to start P s -switching and FE emission.…”

Section: 2 Cathode Surface and Electrodesmentioning

confidence: 99%

“…Later on different methods were studied in other laboratories to extract intense electron beams from FE cathodes (for example, Refs. [14][15][16][17][18][19][20][21][22]), and confusion arose about what is meant by 'ferroelectric electron emission'. The phenomenological appearance and some of the basic processes differ in these latter cases from those in the original 'strong FE emission mode' [4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Features and technology of ferroelectric electron emission

Riege

Boscolo

Handerek

et al. 1998

Journal of Applied Physics

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Spontaneous electrical polarization of ferroelectric materials can be changed either by reversal or by phase transition from a ferroelectric into a non-polar state or vice versa. If spontaneous polarization changes are induced at a submicrosecond time-scale, strong uncompensated surface charge densities and related fields are generated, which may lead to the intense self-emission of electrons from the negatively-charged free surface areas of the ferroelectric cathode. The nature of this self-emission differs essentially from other methods of ferroelectric electron emission and from conventional electron emission in that the latter methods are only achieved by extracting electrons with externally applied electric fields. When electron guns are constructed with ferroelectric cathodes, new design criteria have to be taken into account. The intensity, the energy, the temporal and spatial distribution and the repetition rate of the emitted electron beams can be adjusted within wide limits. The advantages of ferroelectric cathodes and the technological difficulties arising during their production, preparation, and operation are identified and discussed and solutions to the problems are proposed. Experiences with a few applications of ferroelectric electron emission are reported and suggestions for further applications are made.

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Section: Electric-field-excited Fe Electron Emissionmentioning

confidence: 99%

Section: Electric-field-excited Fe Electron Emissionmentioning

confidence: 99%

Section: 1 Fe Materials and Cathode Dimensionsmentioning

confidence: 99%

Section: 2 Cathode Surface and Electrodesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Features and technology of ferroelectric electron emission

Riege

Boscolo

Handerek

et al. 1998

Journal of Applied Physics

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Displacement and emission currents from PLZT 8/65/35 and 4/95/5 excited by a negative voltage pulse at the rear electrode

Benedek

Boscolo

Handerek

et al. 1997

Nuclear Instruments and Methods in Physics Research Section A:

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It is shown that non-prepoled PLZT ceramics, both in ferroelectric and antiferroelectric phase, emit intense current bursts when a negative exciting voltage is applied to the rear surface of the cathode. The spontaneous polarization induced in the bulk by applying the field through the cathode disk, creates a sheet of negative charge on the diode boundary of the ferroelectric. This, in turn, induces such a high electric field at the diode dielectric surface that electrons are ejected out from the ceramic surface into the vacuum. The coherent behaviour of the displacement and emitted current shows clearly that the emission is due to a variation of spontaneous polarization. A second effect generated by the application of the high voltage pulse at the rear side is the formation of a surface plasma. 1-IntroductionA cathode composed by a ferroelectric disk sandwiched by a uniform electrode at the rear surface (RE) and a gridded electrode at the diode side (DE), emits high current pulses when properly excited by a fast electric field. At CERN experiments [1-3], the exciting field was directed from the front emitting surface of the cathode disk to the rear surface (negative excitation), whilst it was opposite in other experiments (positive excitation) [4][5][6][7]. In a previous paper [8] we have presented some results for the case of positive excitation, in this paper we present experimental results and the relative discussion for the case of negative excitation. We have studied the behaviour with and without an accelerating field through the gap of the diode, with the aim of selecting the energetic electrons from the rest and so to single out the ferroelectric effect from the metal-dielectric discharge effect. The samples in our experiments where not prepoled, contrary to experiments of ref.

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Electron emission from ferroelectrics

Rosenman

Shur

Krasik

et al. 2000

Journal of Applied Physics

307

199

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Electron emission from ferroelectrics ͑FEE͒ is an unconventional electron emission effect. Methods of FEE excitation are quite different compared to classic electron emission from solids. Two kinds of FEE have been observed, ''weak'' and ''strong.'' ''Weak'' electron emission ͑current density 10 Ϫ12-10 Ϫ7 A/cm 2 ͒ occurs from polar surfaces of ferroelectric materials in the ferroelectric phase only. A source of the electric field for ''weak'' FEE excitation is an uncompensated charge, generated by a deviation of macroscopic spontaneous polarization from its equilibrium state under a pyroelectric effect, piezoelectric effect, or polarization switching. The FEE is a tunneling emission current which screens uncompensated polarization charges. It is shown that the FEE is an effective tool for direct domain imaging and studies of electronic properties of ferroelectrics. ''Strong'' FEE, which is 10-12 orders of magnitude higher than ''weak'' FEE, achieves 100 A/cm 2 and is plasma-assisted electron emission. Two modes of the surface flashover plasma formation followed by strong electron emission have been studied. The plasma of ferroelectric origin has been observed only in the ferroelectric phase and it is induced by polarization switching or a field-enforced phase transition, such as antiferroelectric-ferroelectric or relaxor-ferroelectric. The second mode of plasma is conventional surface flashover which may be initiated by a high voltage application in any phase from any dielectric, including ferroelectrics. In this review paper we consider numerous experimental results, as well as mechanisms of both types of electron emission from ferroelectrics. The main stress is placed on the material aspect in order to clarify the influence of ferroelectricity ͑ferroelectric phase transitions, polarization switching, etc.͒ on electron emission. Another aspect which is broadly discussed is the potential applications of these unconventional FEE emitters in various devices for development of high density FEE cathodes for microwave devices, as well as FEE converters of IR irradiation into visible light, x-ray imaging, FEE flat panel displays, etc.

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Emission from ferroelectric cathodes. Revision 1

Abstract: This is a preprint of a paper intended forpubli_tion in • jourual orproceedin8_. Since : " _:__: changesmay be madebefore publication,thispreprint is madeavailablewith the ", i_i: ii understanding that it will not be cited or reproduced without the permission of the :.

Cited by 10 publications

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Features and technology of ferroelectric electron emission

Features and technology of ferroelectric electron emission

Displacement and emission currents from PLZT 8/65/35 and 4/95/5 excited by a negative voltage pulse at the rear electrode

Electron emission from ferroelectrics

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