Stable field emission and surface evaluation of surface-processed NbC〈110〉 tips

Ishizawa, Y.; Aizawa, T.; Otani, Shigeki

doi:10.1016/0169-4332(93)90291-i

Cited by 18 publications

(7 citation statements)

References 5 publications

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“…The properties of carbide cold-field emitters have been reviewed by Plomp 3 and Adachi. This is similar to the effect of high emission current treatment of TiC͗110͘ tips used by Adachi,4 and similar treatments of NbC͗110͘ tips by Ishizawa et al 6 to obtain good angular confinement and stability of the emission. This is practically ten times better than the more conventional ultrasharp tungsten tips.…”

Section: Introductionsupporting

confidence: 85%

Energy distributions of field emitted electrons from carbide tips and tungsten tips with diamondlike carbon coatings

Yu¹

1996

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Articles you may be interested inStudy of the fatigue wear behaviors of a tungsten carbide diamond-like carbon coating on 316L stainless steel We have measured the energy distributions of electrons field emitted from tungsten carbide, HfC͗100͘, and ZrC͗100͘ tips, and tungsten field emitters with diamondlike carbon coatings. Multiple-peaked energy distributions were observed from instability induced emission sites on the carbide tips. Energy distributions of electrons field emitted from the diamondlike carbon coated tungsten tips were broader than those from metal tips. They also showed a shift towards lower energies with increases in the emission current.

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Section: Introductionsupporting

confidence: 85%

Energy distributions of field emitted electrons from carbide tips and tungsten tips with diamondlike carbon coatings

Yu¹

1996

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…To reduce or to eliminate the current fluctuation of the step and spike type, the emission current should be reduced, the operation pressure should be reduced or the tip should be heated to remove adsorbed H 2 molecules. Step and spike current fluctuation from a TiC field emitter as a function of the currentpressure product (after [144]). (The fluctuation depends strongly on the flashing temperature prior to operation as indicated in the figure.)…”

Section: Mechanism Of Step and Spike Type Current Fluctuationmentioning

confidence: 99%

“…They report that the current fluctuation depends on the crystalline perfection, the impurity content, the stoichiometry and the way the high temperature flashes. Ishizawa et al conclude that the current stability depends mostly on the surface treatment and that the surface with a monolayer of graphite on top presents the best current stability [144].…”

Section: Mechanism Of Step and Spike Type Current Fluctuationmentioning

confidence: 99%

Fundamental physics of vacuum electron sources

Yamamoto

2005

Rep. Prog. Phys.

131

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The history of electron emission is reviewed from a standpoint of the work function that determines the electron emission capability and of applications in the fields of scientific instruments and displays. For years, in thermionic emission, a great deal of effort has been devoted to the search for low work function materials with high melting temperature, while reduction of the local change in time of the work function rather than the work function itself has been the main issue of field emission investigations. High brightness and long life are the central targets of emission material investigations for scientific instrument applications, while high current density and low power consumption are the guiding principles for display applications.In most of the present day industries, thermionic emission materials are exclusively used in such fields requiring high current and high reliability as cathode ray tubes, transmission and receiving tubes, x-ray sources and various electron beam machines. Field electron emission sources, however, since applied to high resolution electron microscopes in the 1970s have recently become dominant in research and development in the fields of scientific instruments as well as in the fields of various electron tubes and beam machines.The main issue in this report is to analyse the work function on the atomic scale and thereby to understand the fundamental physics behind the work function, the change in time of the local work function leading to field emission current fluctuation and the relationship between microscopic (on atomic scale) and macroscopic work functions.Our attempt is presented here, where the work function on the atomic scale is measured by utilizing a scanning tunnelling microscopy technique, and it is made clear how far the local work function extends its influence over neighbouring sites. As a result, a simple relationship is established between microscopic and macroscopic work functions.

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“…Metal carbides and nitrides are good candidates because they, like metal borides such as LaB 6 , have metallic, covalent, and ionic bonds simultaneously . There have been attempts to apply group 4 and 5 transition-metal carbides (TMCs) to an electron emitter. − Similar attempts have been made for transition-metal nitrides (TMNs). − …”

Section: Introductionmentioning

confidence: 99%

Reduction in Work Functions of Transition-Metal Carbides and Oxycarbides upon Oxidation

et al. 2021

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Herein, the work functions of group 4 and group 5 transition-metal (Ti, Zr, Hf, V, Nb, and Ta) carbides and transition-metal oxycarbides (TMCOs) were investigated by first-principles calculations for their potential application as electron emitters. The work functions of both groups decreased as the substitution of carbon atoms with oxygen proceeded, and the reduction in group 4 was more than that of group 5. In particular, ZrC1–x O x and HfC1–x O x (x ≥ 0.25) exhibited work functions of less than 3 eV, which were comparable with those of LaB6- and ZrO-coated tungsten. The reduction in the work functions could be explained by the rigid-band model of the electronic density of states. The increase in valence electrons increased the Fermi energy, while it demonstrated a less significant influence on the vacuum potential, resulting in a reduction in the work functions. The phonon dispersion curves indicated that the NaCl-type group 5 TMCOs were less stable than the group 4 TMCOs. This agrees with the experimental findings that TaC1–x O x was not synthesized and NbC1–x O x was synthesized only for smaller values of x (i.e., x < 0.28). From the viewpoints of the work functions and structural stabilities, group 4 (Ti, Zr, and Hf) TMCOs exhibit better potential for application as electron emitters than group 5 (V, Nb, and Ta) TMCOs.

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Stable field emission and surface evaluation of surface-processed NbC〈110〉 tips

Cited by 18 publications

References 5 publications

Energy distributions of field emitted electrons from carbide tips and tungsten tips with diamondlike carbon coatings

Energy distributions of field emitted electrons from carbide tips and tungsten tips with diamondlike carbon coatings

Fundamental physics of vacuum electron sources

Reduction in Work Functions of Transition-Metal Carbides and Oxycarbides upon Oxidation

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