Showing papers on "Field electron emission published in 1995"
TL;DR: In this paper, a high-intensity electron gun based on field emission from a film of aligned carbon nanotubes has been made, which consists of a nanotube film with a 1-millimeter-diameter grid about 20 micrometers above it.
Abstract: A high-intensity electron gun based on field emission from a film of aligned carbon nanotubes has been made. The gun consists of a nanotube film with a 1-millimeter-diameter grid about 20 micrometers above it. Field-emission current densities of about 0.1 milliampere per square centimeter were observed for applied voltages as low as 200 volts, and current densities greater than 100 milliamperes per square centimeter have been realized at 700 volts. The gun is air-stable, easy and inexpensive to fabricate, and functions stably and reliably for long times (short-term fluctuations are on the order of 10 percent). The entire gun is only about 0.2 millimeter thick and can be produced with virtually no restrictions on its area, from less than 1 square millimeter to hundreds of square centimeters, making it suitable for flat panel display applications.
3,103 citations
TL;DR: Field emission of electrons from individually mounted carbon nanotubes has been found to be dramatically enhanced when the nanotube tips are opened by laser evaporation or oxidative etching, in a process that resembles unraveling the sleeve of a sweater.
Abstract: Field emission of electrons from individually mounted carbon nanotubes has been found to be dramatically enhanced when the nanotube tips are opened by laser evaporation or oxidative etching. Emission currents of 0.1 to 1 microampere were readily obtained at room temperature with bias voltages of less than 80 volts. The emitting structures are concluded to be linear chains of carbon atoms, Cn, (n = 10 to 100), pulled out from the open edges of the graphene wall layers of the nanotube by the force of the electric field, in a process that resembles unraveling the sleeve of a sweater.
1,538 citations
TL;DR: In this paper, the lowest reported field, < 0.2 V εμm−1, was characterized as a function of surface treatment of diamond field emitters, Cs treated, air stable, and carbonized polymer.
Abstract: This letter reports, diamond field emitters, Cs treated, air stable, that emit electrons at the lowest reported field, <0.2 V μm−1. Field emission from B‐, Li‐, P‐, and N‐doped diamonds and carbonized polymer was characterized as a function of surface treatment. A treated with an O2 plasma, coated with Cs, heated, and exposed to O2 exhibited increased emission for all samples except for B‐doped diamond. The best emission was obtained from N‐doped diamond samples, followed by carbonized polymer, the Li‐doped, and polycrystalline P‐doped diamond. Li‐ and N‐doped samples treated with Cs were stable in laboratory air for several days. This stability of the surface‐activated diamond is believed to be due to the formation of a diamond–O–Cs salt. If the sample is treated with a H2 plasma instead of an O2 plasma, the Cs‐enhanced emission degrades with heat and exposure to O2. Subbands formed by Li and N impurities are believed to be responsible for this enhanced emission. The surface treatment on N‐doped diamond ...
297 citations
Abstract: Diamond samples with varying defect densities have been synthesized by chemical vapor deposition, and their field emission characteristics have been investigated. Vacuum electron field emission measurements indicate that the threshold electric field required to generate sufficient emission current densities for flat panel display applications (≳10 mA/cm2) can be significantly reduced when the diamond is grown so as to contain a substantial number of structural defects. The defective diamond has a Raman spectrum with a broadened peak at 1332 cm−1 with a full width at half maximum (FWHM) of 7–11 cm−1. We establish a strong correlation between the field required for emission and the FWHM of the diamond peak. The threshold fields are typically less than 50 V/μm and can reach as low as 30 V/μm for diamond with a FWHM greater than 8.5 cm−1. It is believed that the defects create additional energy bands within the band gap of diamond and thus contribute electrons for emission at low electric fields.
287 citations
TL;DR: In this article, the electron tunnelling in device grade ultra-thin 3-6 nm n + poly-Si/SiO 2 /n-Si structures has been analyzed.
Abstract: In this work the electron tunnelling in device grade ultra-thin 3–6 nm n + poly-Si/SiO 2 /n-Si structures has been analysed. The well known analytic expression for the Fowler-Nordheim tunnelling current was adapted to include the case of direct tunnelling of electrons, which becomes important for oxide layers thinner than 4.5 nm. For these ultra-thin oxide MOS structures it is necessary to take the band bending in the Si substrate and in the poly-Si layer into account to determine the oxide electrical field strength and to derive the tunnelling parameters of the measured current-voltage characteristic. A method is explained to derive the tunnel barrier height φ s and the effective mass of the tunnelling electron m ox from the experimental tunnel current characteristics. It is shown that both the direct tunnelling and the Fowler-Nordheim tunnelling current can be quantitatively explained by a WKB approximation using m ox as the single fitting parameter.
256 citations
TL;DR: In this paper, the authors observed significant field emission from the surface of nanofilament carbon structure films on various substrates (Si, quartz, glass) while the electric field was about 100 V/μm.
179 citations
TL;DR: In this article, the role of defects in the electron emission from undoped or p-type doped diamond and indicate that the improved emission characteristics of as-implanted diamond is due to the defects created by the ion implantation process.
Abstract: Diamond films and islands grown by chemical vapor deposition were implanted with boron, sodium, and carbon ions at doses of 1014–1015/cm2. This structural modification at the subsurface resulted in a significant reduction of the electric field required for electron emission. The threshold field for producing a current density of 10 mA/cm2 can be as low as 42 V/μm for the as‐implanted diamond compared to 164 V/μm for the high quality p‐type diamond. When the ion‐implanted samples were annealed at high temperatures in order to anneal out the implantation‐induced defects, the low‐field electron emission capability of diamond disappeared. These results further confirm our earlier findings about the role of defects in the electron emission from undoped or p‐type doped diamond and indicate that the improved emission characteristics of as‐implanted diamond is due to the defects created by the ion implantation process.
171 citations
TL;DR: In this paper, the authors used field-emission scanning electron microscopy (FE-SEM) to study compositional superlattices with n and p doping at low voltages (0.5-1 kV) in both cross-sectional and oblique plan-views after indentation.
165 citations
TL;DR: In this paper, an alternative mechanism for electron emission from the ferroelectric ceramic cathode was proposed, which involves the concept of vacuum breakdown initiation from metal-dielectric cathodes that comprises two stages: the field emission through metal dielectric-vacuum conjunction followed by the processes resulting in an uncompleted surface discharge.
Abstract: This article suggests an alternative mechanism for electron emission from the ferroelectric ceramic cathode. This mechanism involves the concept of vacuum breakdown initiation from metal‐dielectric cathodes that comprises two stages: the field emission through metal‐ dielectric‐vacuum conjunction followed by the processes resulting in an uncompleted surface discharge. The electron emission thus occurs from the low‐density surface plasma.
109 citations
TL;DR: In this article, the electron emission from CVD-grown phosphorus (P-) and boron (B)-doped polycrystalline diamond films was studied and a ratio of 0.66 for the emission barrier height was obtained.
Abstract: The electron emission from CVD-grown phosphorus (P-) and boron (B)-doped polycrystalline diamond films has been studied. The current density against electric field characteristics of the P-doped film showed low-field emission compared to the B-doped film. From the slope ratio of the Fowler-Nordheim (F-N) characteristics of P- and B-doped films, a ratio of 0.66 for the emission barrier height was obtained. The small ratio might be caused by the n-type semiconducting properties of P-doped diamond films. >
104 citations
TL;DR: In this paper, a diamond-coated silicon field emitters were fabricated and investigated, and the results showed that the effective work function calculated from Fowler-Nordheim plot were in the range from 0.3 to 1.2 eV.
Abstract: Diamond‐coated silicon field emitters were fabricated and investigated. Emission currents of few μA per tip at voltages of several hundred volts were obtained from very blunt tips with curvature radii up to 3 μm. The values of the effective work function calculated from Fowler–Nordheim plot were in the range from 0.3 to 1.2 eV. Two models for an explanation of the experimental data are proposed.
TL;DR: In this article, a double-gated Si field emitter array capable of generating focused electron beams was fabricated and experimentally evaluated, and it was found from experimental results that decreasing the upper gate voltage (VF) down to a few volts was quite effective to generate focused electron beam.
Abstract: Double‐gated Si field emitter arrays (FEAs) capable of generating focused electron beams were fabricated and experimentally evaluated. The present field emitter array has a vertical triode structure consisting of a conical Si tip and two gate openings (upper and lower) surrounding the tip. The lower gate with a 2‐μm‐diam opening acts as an extraction electrode controlling the emission current, and the upper one with a 3‐μm‐diam opening acts as an electrostatic lens focusing the electron trajectories. The focusing property was evaluated by observing the spot size of a phosphor (ZnO:Zn) screen located about 20 mm apart from the field emitter array and biased to 1 kV. It was found from experimental results that decreasing the upper gate voltage (VF) down to a few volts was quite effective to generate focused electron beams. At VF of about 4 V, the electrons emitted from the tip were well collimated and a beam current of about 0.1 nA/tip was obtained.
Patent•
14 Feb 1995TL;DR: A field emission electron emitter comprising an electrode formed of at least one diamond, diamond-like carbon or glassy carbon composite fiber is defined in this paper, where composite fiber consisting of a non-diamond core and a diamond or diamondlike carbon coating on the core.
Abstract: A field emission electron emitter comprising an electrode formed of at least one diamond, diamond-like carbon or glassy carbon composite fiber, said composite fiber having a non-diamond core and a diamond, diamond-like carbon or glassy carbon coating on said non-diamond core, and electronic devices employing such a field emission electron emitter.
TL;DR: In this article, the field emission data from p-type polycrystalline diamond films were presented, and a current of approximately 50 nA was observed at a pressure up to 10−2 Torr in H2 environment.
Abstract: Vapor‐deposited‐diamond field emitters are fabricated using diamond film technology compatible with integrated circuit processing. The field emission data from p‐type polycrystalline diamond films are presented. Field emission current in the range of 15 μA was detected at an electric field intensity of <20 MV/m at a pressure of 10−7 Torr. A current of approximately 50 nA was observed at a pressure up to 10−2 Torr in H2 environment.
TL;DR: In this article, an interface trap-assisted tunneling and thermionic emission model has been developed to study an increased drain leakage current in off-state n-MOSFET's after hot carrier stress.
Abstract: An interface trap-assisted tunneling and thermionic emission model has been developed to study an increased drain leakage current in off-state n-MOSFET's after hot carrier stress. In the model, a complete band-trap-band leakage path is formed at the Si/SiO/sub 2/ interface by hole emission from interface traps to a valence band and electron emission from interface traps to a conduction band. Both hole and electron emissions are carried out via quantum tunneling or thermal excitation. In this experiment, a 0.5 /spl mu/m n-MOSFET was subjected to a dc voltage stress to generate interface traps. The drain leakage current was characterized to compare with the model. Our study reveals that the interface trap-assisted two-step tunneling, hole tunneling followed by electron tunneling, holds responsibility for the leakage current at a large drain-to-gate bias (V/sub dg/). The lateral field plays a major role in the two-step tunneling process. The additional drain leakage current due to band-trap-band tunneling is adequately described by an analytical expression /spl Delta/I/sub d/=Aexp(B/sub it//F). The value of B/sub it/ about 13 mV/cm was obtained in a stressed MOSFET, which is significantly lower than in the GIDL current attributed to direct band-to-band tunneling. As V/sub dg/ decreases, a thermionic-field emission mechanism, hole thermionic emission and electron tunneling, becomes a primary leakage path. At a sufficiently low V/sub dg/, our model reduces to the Shockley-Read-Hall theory and thermal generation of electron-hole pairs through traps is dominant. >
TL;DR: In this paper, the authors demonstrated that straightforward operation of an LVSEM equipped with a field emission gun (FEG) source can produce topographical contrast secondary electron images of polymers at substantially higher magnifications than a conventional SEM, and with a resolution that rivals TEM.
TL;DR: In this article, single crystal silicon field emitters have been modified by surface deposition of diamond using biasenhanced microwave plasma chemical vapor deposition Polycrystalline diamond with a high nucleation density (1010/cm2) and small grain size (<20 nm) was achieved on silicon-field emitters.
Abstract: Single crystal silicon field emitters have been modified by surface deposition of diamond using bias‐enhanced microwave plasma chemical vapor deposition Polycrystalline diamond with a high nucleation density (1010/cm2) and small grain size (<20 nm) was achieved on silicon field emitters Field emission from these diamond coated emitters exhibited significant enhancement both in total emission current and stability compared to pure silicon emitters A large effective emitting area comparable to the tip surface area was obtained from a Fowler–Nordheim analysis The effective work function of the polycrystalline diamond coated emitter surface was found to be larger than that of a pure silicon emitter surface
TL;DR: In this article, the authors carried out preliminary experiments of the idea and showed that the controllability and the stability of emission current of FEA were significantly improved by an actively controlled FEA.
Abstract: The current control and the stabilization in field emission of gated field emitter arrays (FEAs) are the highest demand for applications to a flat panel display and other beam devices. The concept of the field‐effect‐controlled field emission cathode is very useful for these purposes. We carried out preliminary experiments of the idea and showed that the controllability and the stability of emission current of FEA were significantly improved by an actively controlled FEA. Additionally, we discussed beam focusing of FEA for a flat panel display application.
TL;DR: In this article, the authors report experiments conducted to review several factors closely related to emission quality required for flat panel displays, using the measurement of the emission of fabricated Spindt-type emitters.
Abstract: This article reports experiments conducted to review several factors closely related to emission quality required for flat panel displays. Using the measurement of the emission of fabricated Spindt‐type emitters, the dependence of current density on the distance from the tip of an emitter cone to the upper surface of the gate was investigated. It was also confirmed that the shape of the emitter cone was largely affected by the gate hole diameter and material of cone. The maximum half‐angle of emission on anode from a tip was compared between the simulated electron beam spread and actual measurements made for emitter arrays.
TL;DR: In this paper, structural and field-emission studies of diamond-coated tips were performed and two approaches for the observed emission behavior were proposed: (1) NEA-affected emission and (2) emission from sharp nano-size points.
TL;DR: In this paper, electron emission from ferroelectric thin films (≤1 μm thick) is demonstrated using an Auger electron spectrometer, and electron energy distributions have been measured using an electron energy distribution.
Abstract: Electron emission from ferroelectric thin films (≤1 μm thick) is demonstrated. In addition, electron energy distributions have been measured using an Auger electron spectrometer. The electron emission measurements were performed using ferroelectric cathodes based on this Pb(Zr0.53Ti0.47)O3 (PZT) films and 80–110 μm Pb0.93La0.07(Z0.53Ti0.47)O3 (PLZT) layered capacitors with Pt top and bottom electrodes. Current densities in the range of 0.5–1.5 mA/cm2 were measured from the PLZT cathodes excited with 100–400 V pulses, which produced electrons of about 265 eV with a narrow energy distribution (full width at half‐maximum of about 30 eV). On the other hand, current densities in the range 0.07–0.15 μA/cm2 were measured for thin film PZT‐based cathodes excited with pulses in the range 10–40 V. The initial results suggest that the electron emission current may depend, among other factors, on the thickness of the ferroelectric layer, the applied excitation voltage, and the interval between the polarizing and switching pulses.
TL;DR: In this article, a simple field emission device (FED) was used to detect electron emission from chemical vapor deposited (CVD) diamond and amorphous carbon (a-C) films.
Abstract: Electron emission from chemical vapor deposited (CVD) diamond and amorphous carbon (a-C) films was observed with a simple field emission device (FED). Both diamond and a-C films were prepared with microwave plasma-enhanced CVD techniques. Electron emission in the ficld strength range + 10 to −10 MVm−1 was studied, and the field emission source was confirmed by a diode characteristic of the I-V curve, a straight line in the Fowler-Nordheim (F-N) plot, and direct observation of light emission from a fluorescent screen. The turn-on field strength was ∼5 MVm−1, which was similar for both kinds of carbon films. The highest current density for diamond films, observed at a field strength of 10 MVm−1, was ∼15 μA cm−2. Diamond films yielded a higher emission current than a-C films. The reasons for the observed field emission are discussed.
TL;DR: In this article, the authors present nanostructure fabrication techniques using field evaporation and local heating in scanning probe microscopes, especially the scanning tunneling microscope (STM), atomic force microscope (AFM), and the scanning near field optical microscope (SNOM).
Abstract: We present nanostructure fabrication techniques using field evaporation and local heating in scanning probe microscopes, especially the scanning tunneling microscope (STM), atomic force microscope (AFM), and the scanning near‐field optical microscope (SNOM). The detachment of sulfur atoms from the surface of cleaved MoS2 and atomic scale fabrication were demonstrated with a field evaporation in STM. Field evaporation in AFM forms nanometer‐sized gold dots on a SiO2/Si substrate. Local heating with SNOM changes a phase of the GeSbTe recording film from amorphous to crystalline, and forms high reflectivity domains 60 nm in diameter. Moreover, we discuss these applications to a semiconductor process and data storage.
TL;DR: In this paper, the tunneling current through gate oxides has been measured as a function of the voltage across SiO2, V OX, and compared with results of existing theories utilizing the WKB approximation.
Abstract: The tunneling current through ultrathin (3.0-6.0 nm) gate oxides has been measured as a function of the voltage across SiO2, V OX, and compared with results of existing theories utilizing the WKB approximation. The electron effective mass in the Fowler-Nordheim tunneling region (V OX≥3.25 V) is obtained to be (0.34±0.04)m0 and that in the direct tunneling region (V OX<3.25 V) is (0.29±0.02)m0. It is also shown that the charge-to-breakdown for electron injection from n+poly-Si gates is not significantly degraded by decreasing the oxide thickness and is even dramatically improved for the case of a 3.0 nm-thick gate oxide.
TL;DR: In this paper, the effect of negative electron affinity, the band bending, the image interaction, and surface states on the electron field emission from diamond surfaces is investigated theoretically using a model consisting of the projection of the energy-band surfaces in the 〈111〉, � 110〉 and � 100〉 emission directions.
Abstract: The electron field emission from diamond surfaces is investigated theoretically using a model consisting of the projection of the energy‐band surfaces in the 〈111〉, 〈110〉, and 〈100〉 emission directions. The effect of the negative electron affinity, the band bending, the image interaction, and surface states are examined in detail. It is found that the tunneling from the bulk conduction and valence bands is negligible in p‐type diamond. While emission from surface states located about 1 eV below the conduction band has sufficient transmission probability to produce currents observed in experiments, there is no obvious transport mechanism in intrinsic, doped, or polycrystalline diamond to sustain a direct field emission current. We postulate two subbands in the intrinsic band gap, which may be generated by defects or impurities. With reasonable band parameters, the calculated j–F characteristics agree with experimental data.
TL;DR: In this paper, the authors performed experiments of considerable field emission from the films consisting of nanotube carbon structures and found that the density of emission current was up to 3 A/cm2, while in 20-100 V/μm electric field it was 0.1-1 mA/mm2.
Abstract: We present the finding of newly performed experiments of considerable field emission from the films consisting of nanotube carbon structures. Density of emission current was up to 1–3 A/cm2, while in 20–100 V/μm electric field it was 0.1–1 mA/mm2.
Patent•
NEC1
TL;DR: In this paper, the authors presented an emitter structure of a field emission electron gun with an electrically conductive emitter being pointed at the top, where the top of the emitter has the highest resistance of every other part.
Abstract: The present invention provides an emitter structure of a field emission electron gun. The emitter structure comprises an emitter being electrically conductive and being pointed at the top, wherein the top of the emitter has the highest resistance of every other part, so that the top of the emitter has the highest heat energy of every other part when the emitter emits electrons.
TL;DR: In this article, a Monte Carlo simulation is employed to model the scattering of the primary electrons in a tip and to compute the spatial distribution of energy left in the tip, highlighting the influence of beam energy, beam current, and precursor material on the morphology and electrical properties of the deposited material.
Abstract: Electron‐beam induced deposition has been shown to be capable of creating structures of nanometer size in three dimensions without supplementary process steps like lift‐off or etching procedures. Tips can be produced with radii of curvature comparable to the beam diameter used for deposition, i.e., some nanometers. By choosing appropriate deposition conditions, vacuum field emitter tips yielding a current of more than one hundred micro amps at 22 V gate voltage have been fabricated. This article will discuss the decomposition process of different organometallic precursor molecules by electron impact. A Monte Carlo simulation is employed to model the scattering of the primary electrons in a tip and to compute the spatial distribution of energy left in the tip. The influence of beam energy, beam current, and precursor material on the morphology and electrical properties of the deposited material are highlighted.
01 Mar 1995
TL;DR: In this article, it has been found that sharp diamond cones can be formed by ion milling if diamonds are in the form of isolated grains and that the field emission current from diamond/Si samples is drastically increased by Ar ion millings and subsequent heat treatment in vacuum.
Abstract: Diamond grains were grown on Si substrates by plasma‐enhanced chemical vapor deposition. Ar ion milling was applied to the diamond/Si structures. It has been found that sharp diamond cones can be formed by ion milling if diamonds are in the form of isolated grains. It has also been found that the field emission current from diamond/Si samples is drastically increased by Ar ion milling and subsequent heat treatment in vacuum.
TL;DR: In this paper, the authors measured the electron emission from a CsI-coated multiwire cathode, induced by ultraviolet photons and electrons, in vacuum at high electric fields and found an enhancement in quantum efficiency of a factor of 1.5 at 160 nm, 3 at 185 nm, and 25 above 200 nm, at a field of 500 kV/cm.
Abstract: We have measured the electron emission from a CsI‐coated multiwire cathode, induced by ultraviolet photons and electrons, in vacuum at high electric fields. We found an enhancement in quantum efficiency of a factor of 1.5 at 160 nm, 3 at 185 nm, and 25 above 200 nm, at a field of 500 kV/cm. At the short wavelengths the amplitude of the effect is a linear function of the square root of the field strength. The enhancement of the electron‐induced secondary electron emission yield is dependent on the primary electron energy: for energies above 1 keV it varies by a factor of 2 to 10. A simple model of the field enhancement of the photoemission is suggested. Practical applications are discussed.