Showing papers on "Field electron emission published in 1988"

Electron source with micropoint emissive cathodes and display means by cathodoluminescence excited by field emission using said source

Abstract: Electron source with micropoint emissive cathodes and display means by cathodoluminescence excited by field emission and using said source. Each cathode (5) comprises an electrically conductive layer (22) and micropoints (12) and, according to the invention, a continuous resistive layer (24) is provided between the conductive layer and the micropoints. The display means comprises a cathodoluminescent anode (16) facing the source.

Display unit by cathodoluminescence excited by field emission

Abstract: Display unit by cathodoluminescence excited by field emission. It comprises a plurality of elimentary patterns, each having a cathodoluminescent anode and a cathode able to emit electrons. Each cathode comprises a plurality of electrically interconnected micropoints subject to electron emission by field effect when the cathode is negatively polarized compared with the corresponding anode, the electrons striking the latter, which is then subject to a light emission. Each anode is integrated to the corresponding cathode. Application to the display of stationary or moving pictures.

Method for providing polyimide spacers in a field emission panel display

Abstract: A flat panel display of the field emission cathode type is described having polyimide spacers or pillars separating the emitting surface and display face of the same. A method of forming the spacers by integrated circuit techniques also is described.

Fine structure in field emission resonances at surfaces

Abstract: SUMMARY We have measured field-emission resonances (FER) to much higher quantum states than previously observed enabling fine structure in the resonance amplitudes to be investigated. We show that this electron wave interference effect carries additional information in the resonance amplitudes and energies and is sensitive to lateral tip position in a scanning tunnelling microscope experiment. We propose a new method of data analysis that can distinguish between some of the possible origins of the fine structure.

Tunneling from an ultrathin quantum well in a strong electrostatic field: A comparison of different methods

Abstract: A case study of field emission from a zero-range quantum well has been carried out. The various strong-field approximations, both time-dependent and time-independent, are discussed and compared with exact numerical results. The exponential decay law is shown to be a good approximation on the average, but it cannot account for short-time ripples in the ionisation probability.

Microwave integrated distributed amplifier with field emission triodes

Abstract: The disclosed microwave distributed amplifier includes a plurality of cascaded field emission triodes, each having a field emission element for emitting electrons, a grid disposed downstream from the field emission element along the electron flow path and an anode disposed further downstream along the electron flow path. A series of inductive strips interconnect successive grids to form a grid transmission line, while another series of inductive strips interconnect successive anodes to form an anode transmission line. Small electron transit times over integrated circuit distances in a vacuum environment and low interelectrode capacitance allow extremely large gain-bandwidth products to be achieved.

Electron source comprising emissive cathodes with microtips, and display device working by cathodoluminescence excited by field emission using this source

Abstract: Each cathode (5) comprises an electrically conducting layer (22) and microtips (12) and, according to the invention, a continuous resistive layer (24) is provided between the conducting layer and the microtips. The display device comprises a cathodoluminescent anode (16) opposite the source.

A modification to the Fowler-Nordheim tunneling current calculation for thin MOS structures

Abstract: This paper presents a new computer modeling of Fowler-Nordheim (F-N) tunneling current from an inverted silicon surface to the metal gate of the thin oxide MOS structures. In this model the tunneling current through the oxide is taken to be proportional to the product of the gate oxide field and the inversion layer carrier concentration. Within the semiconductor the standard semiconductor equations are solved to ensure electron current at the semiconductor surface is equal to the tunneling current through the oxide. The computational results indicate that the current-voltage characteristics of the structure would saturate if it is limited by carrier generation in the space-charge region of the silicon. This is known from previous experimental results reported in the literature.

Evidence of Schottky emission in scanning tunneling microscopes operated in ambient air

Abstract: We demonstrate that the electron transfer mechanism in scanning tunneling microscopes operated in air follows the Schottky equation. Schottky emission dominates electron transfer mechanism in microscopes operated in air because of low effective potential barrier heights. This is supported by currents and gap distances that are larger than when tunneling is the predominant electron transfer mechanism.

A new perspective on the origin of prebreakdown electron emission processes

Abstract: An account is presented of two probe techniques that have been used to locate and study the physical properties of individual electron emission sites on broad-area high-voltage electrodes. Details are given of the typical microgeometry and elemental composition of the particulate structures responsible for the emission, and the electron spectral and projection image characteristics of the emission process. These findings are discussed in terms of a recently proposed field-induced hot-electron emission (FIHEE) mechanism that involves a composite metal-insulator emission regime. Finally, the technological implications of these recent developments are considered. >

Coherent electron emission from point sources

Abstract: SUMMARY We study the electron emission and propagation in ultrasharp tips field-emission experiments. The intensity-voltage characteristics as well as the angular spreading of the electron beam is analysed. We show that non-coherent emission cannot explain the very narrow experimental electron beams. The properties of coherent electron sources and the beam spatial coherence width are discussed. The quantum mechanical current distribution of field-emitted electrons from tubes seems to explain the experimental beam widths.

Field-induced electron emission through Langmuir-Blodgett multilayers

Abstract: Field-induced electron emission from silver cathodes coated with Langmuir-Blodgett (LB) films has been studied for range of film thicknesses. This organic-film-coated cathode structure is analogous to previously studied metal-insulator-metal (MIM) structures but without the possible complication of film damage due deposition of the top electrode. The results are discussed with reference to these previous MIM studies and in comparison with the results from other cathode-coated structures showing enhanced electron emission. The qualitative features of the electron emission suggest the formation of persistent conducting filaments, while energy analysis of the emission shows both inelastic and hot-electron features.

Ultra High Resolution Scanning Electron Microscopy

Abstract: An ultra high resolution scanning microscope (UHRSEM) which is composed of a cold cathode field emission electron gun and an in-lens system for specimens, has been introduced. Probe size is estimated approximately 0.5∼0.7 nm at an accelerating voltage of 30 kV by calculation, and it was confirmed experimentally using high atomic number fine particles. Fine metal oxide particles and semiconductor materials were observed directly without any metal coating. A necessity of the UHRSEM has been discussed especially for low voltage SEM (LVSEM) to obtain fine topographical details of the samples, which are very sensitive to the scanning electron beams.

Field‐stimulated exoelectron emission from 99.9999% pure Al

Abstract: Exoelectrons were emitted from a 99.9999% pure Al tip by applying an electric field as a stimulus. This occurred at lower voltages than that necessary for field emission of electrons. Field‐stimulated exoelectron emission showed a characteristic storage effect in accordance with the time interval of applied voltage pulses. Based upon this storage effect and a computer calculation of the field strength at the apex of the tip, we show by analytical discussions that exoelectrons are emitted by tunneling, not by the Schottky effect.

A thermally assisted field emission electron beam exposure system

Abstract: Electron beamlithography is widely used to fabricate densely packed devices such as high‐frequency transistors, since optical lithography is unable to write the small patterns required for such devices One major problem with micropattern writing with an electron beam exposure system, however, is slow writing speed; since the system has to write an extremely large number of patterns on low‐sensitivity resist with a highly focused beam, exposure times are quite long To speed up the writing process, we have attached a thermal field emission gun to our electron beam exposure system This gun is designed to increase the electron sourcebrightness and probe current density In order to determine this new probe current density, we conducted an extensive evaluation on a complete lithography system which uses a thermal field emission gun We have measured a current density of ∼1000 A/cm2 at an accelerating voltage of 25 kV and conclude that this lithography system can be put to practical use in production areas requiring high throughput and submicron exposures

Comparison of low-voltage field emission from TaC and tungsten fiber arrays

Abstract: Field emitter array (FEA) devices were constructed using thin-film fabrication techniques based on in situ eutectic composites containing either TaC or NbC fibers in a NiCr alloy matrix. The emission characteristics of the TaC devices were measured and compared to those of W--ZrO/sub 2/ FEA's. Both devices produced the linear Fowler--Nordheim plots common to all field emission devices; however, the array current density of the TaC FEA's was more than two orders of magnitude lower than that of the W--ZrO/sub 2/ FEA's. This was primarily due to the lower fiber density and lower field enhancement of the carbide fiber devices. If it were possible to produce cathode geometries comparable to those of the W--ZrO/sub 2/ FEA's, a theoretical analysis indicates that emission performance of the TaC devices would be superior because of the lower work function of TaC. However, post-emission observations indicated that the carbide fiber emitters failed more readily than the tungsten emitters under comparable operating conditions.

Effects of backsputtered material on gallium liquid metal ion source behavior

Abstract: Backsputtered material is demonstrated to be a major factor in determining gallium liquid metal ion source (LMIS) lifetimes and I‐V characteristics during operation in ultrahigh vacuum. The behavior of LMIS emission current is extremely sensitive to the type of material backsputtered onto the source tip, shaft, and reservoir. The assimilation of sputtered material is important in maintaining stable ion emission and is found to depend on the miscibility of the contaminant material in gallium. Materials which do not form solid phases when mixed with liquid gallium have the least effect on ion currents.

Enhanced field emission from molybdenum disulfide

Abstract: Field emission properties of MoS/sub 2/ particles on clean niobium electrodes were investigated, and emitting particles were localized and studied. Studies on natural MoS/sub 2/ where high emissivity was found for the basal planes oriented perpendicular to the surface are also presented. These results are discussed in the light of existing models for enhanced field emission. >

The spatial and temporal behavior of electron emission sites during helium conditioning

Abstract: An optical imaging technique for visually displaying the spatial and temporal behavior of electron emission sites during helium conditioning over a time scale of approximately 20 min. is described. This has been used to confirm that the conditioning process is permanent and that there exists an upper field limit of approximately 40 MVm/sup -1/ beyond which no conditioning occurs. Electron spectroscopy measurements have been made at emission sites before and after a period of conditioning and reveal a spectral shift of approximately 0.4 eV to higher energies and a decrease of approximately 0.6 eV in the spectral FWHM (full width at half maximum) after conditioning: these findings suggest that an electronic process could be involved in the conditioning mechanism. The optical imaging technique has also been used to confirm that there is a spatial correlation between emission sites and breakdown events. >

Comparison of data transfer rates of focused electron and ion beam nanometer lithography

Abstract: Light ions such as protons incident on organic resists (polymethylmethacrylate) deposit their energy very efficiently in well‐defined volumes with no backscattering. These characteristics make protons the best medium for writing nanometer structures in the lithographic process. To write nanometer structures with focused electron beams the electrons must be accelerated to energies of 50 to 100 KeV where the interaction cross sections are very small and very large doses of electrons are needed and to avoid backscattering, thin‐film substrates have been used. We have taken the dosages of electrons and protons that investigators have found are necessary to write 10‐ and 30‐nm lines and using the characteristics of the very high brightnesssources that are now available with field emission electron beams and gaseous field ion beams of H+ 2 and calculated the data transfer rates for writing these nanometer structures. Focused protonion beamlithography gives data transfer rates two orders of magnitude faster than focused electron beams for writing 30‐nm pixels; 1.6×108 Hz for protons versus 3.0×106 Hz for electrons.

Laser-stimulated field desorption of molecular ions from a tungsten emitter

Abstract: We report here on a experimental observation of photon-stimulated field emission of molecular anthracene ions from the surface of a layer adsorbed on a tungsten field-emitter tip. When the tip is irradiated with laser pulses 249, 308, and 400 nm in wavelength falling within the absorption bands of anthracene, the stimulated ion signal is proportional to the pulse fluence. The efficiency of the process decreases with the increasing laser wavelength. Photon stimulation is believed to be due to the resonance excitation of the anthracene molecules, followed by the field ionization of the excited molecules.

Field emission type electron generation device

Abstract: PURPOSE:To cleans the vicinity of a chip for setting up long-term stabilization of emission by making thermal electrons from a heating body to collide with adsorptive gas molecules at a high speed CONSTITUTION:A high voltage is impressed between lead rods 14a/14b fixed to a heating body 21 and an extraction electrode 5 for accelerating thermal electrons to make them to collide with the extraction electrode 5 and a protective umbrella 22 The collision activates gas molecules adsorbed to the extraction electrode 5 and the protective umbrella 22 for discharging them outside by an ion pump

Field emission from semiconductor point arrays

Abstract: The paper reports on the fabrication of multi-point arrays from Ge, Si, and GaAs by means of optimization of photolithographic method. The origin of uncontrollable centres of emission on the surface has been investigated by means of SEM, AE- and SIM-spectroscopy. An investigation of the electron energy distribution from the probing zone of cathode surface at different operating modes of the cathode have shown the "broadening" of distribution with the increase of current take-off level. By measuring the frequency characteristics of the field emission current fluctuations it has been found that the noise power spectrum is well approximated by the I/f function in the low frequency range.