Good Electron Emission Properties Research Articles

Investigation of the Field Emission Stability of Sphere-Like Diamond Microcrystalline-Aggregates Films

The sphere-like diamond microcrystalline-aggregates were fabricated by microwave plasma chemical vapor deposition (MPCVD) method. The ceramic with a Ti metal layer was used as substrates. The fabricated diamond microcrystalline aggregates were evaluated by Raman scattering spectroscopy, x-ray diffraction spectrum (XRD), scanning electron microscopy (SEM). The field emission properties were tested by using a diode structure in a vacuum. A phosphor-coated indium tin oxide (ITO) anode was used for observing and characterizing the field emission. It was found that the sphere-like diamond microcrystalline-aggregates films exhibited good electron emission properties. The turn-on field was only 0.55V/μm, and emission current density as high as 11mA/cm2 was obtained under an applied field of 2.18V/μm for the first operation. After several cycling operations, the field emission tended to stable characteristics of current versus voltage. The stability evolvement and mechanism are investigated relating to microstructure of the sphere-like diamond microcrystalline-aggregates films.

Diamond electron emission

Abstract

The Field Emission of Globe-Like Diamond Microcrystalline Aggregate Films

The globe-like diamond microcrystalline aggregates films were fabricated by microwave plasma chemical vapor deposition method. The field emission properties and emission stability of the films were tested using a diode structure in vacuum. It was found that the globe-like diamond microcrystalline aggregates films exhibited good electron emission properties and stability. The turn-on field of 0. 55 V /μm and the current density of 11mA/cm2 at the electric fields of 2.73V/μm were obtained. At the successive operator circles, the turn-on field tends to stabilize at 1. 08V /μm and the current density of 6.6 mA/cm2 is obtained.

Field emission properties of the globe-like diamond microcrystalline aggregate films grown by MPCVD

The globe-like diamond microcrystalline aggregate films were fabricated by microwave plasma chemical vapor deposition (MPCVD) method and the field emission properties were investigated using a diode structure in vacuum. It was found that the films had a complex structure with globe-like microcrystalline diamond aggregations grown on the a-C surface and these films exhibited good electron emission properties and stability. The turn-on field of 1.1 V/μm and the current density of 6.6 mA/cm2 were obtained for these diamond microcrystalline aggregate films at the electric field of 2.73 V/μm.

Direct Growth of Quasi-Aligned Ultrafine ZnS Nanowire Arrays on Conducting Zinc Foils and Their Field Emission Properties

Quasi-aligned ultrafine ZnS nanowire arrays have been grown directly on zinc substrates via a simple hydrothermal method. The morphology, structure, and composition are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. The single-crystalline ultrafine ZnS nanowires have a hexagonal structure with typical diameters of 5-15 nm and lengths of up to micrometers. A possible growth mechanism is proposed. Since the Zn foil serves as both the Zn source and substrate, direct synthesis and assembly of ZnS nanowires on an electrically conductive Zn substrate are accomplished in one step. Optical properties of the product are studied by photoluminescence. Field emission measurements disclose that the synthesized nanostructures possess good electron emission properties with a low turn-on field of about 5.4 V/microm at a current density of 10 microA/cm2. The materials are potentially useful as cathode materials in field emission devices.

Growth and field emission properties of globe-like diamond microcrystalline-aggregate

The globe-like diamond microcrystalline-aggregates were fabricated by microwave plasma chemical vapor deposition (MPCVD) method. The ceramic with a Ti mental layer was used as substrate. The fabricated diamond was evaluated by Raman scattering spectroscopy, X-ray diffraction spectrum (XRD), and scanning electron microscope (SEM). The field emission properties were tested by using a diode structure in a vacuum. A phosphor-coated indium tin oxide (ITO) anode was used for observing and characterizing the field emission. It was found that the globe-like diamond microcrystalline-aggregates exhibited good electron emission properties. The turn-on field was only 0.55 V/μm, and emission current density as high as 11 mA/cm 2 was obtained under an applied field of 2.9 V/μm for the first operation. The growth mechanism and field emission properties of the globe-like diamond microcrystalline-aggregates are discussed relating to microstructure and electrical conductivity.

Development of a Diamond Electron Source for Electron Optics Instruments and Evaluation of Energy Spread using the Source

Diamond that shows low or negative electron affinity has good electron emission properties. The authors are developing a diamond electron source, which is suited for electron optics instruments such as electron beam exposure systems and electron microscopes. As a result of thermionic emission evaluations, an electron emission current of practical level (116 μA at 600oC) was obtained. The energy spread of an electron beam generated by thermionic emission was measured as 0.23 eV (FWHM), the value of which was lower than those of a LaB6 cathode and a ZrO/W cathode measured together. The result of field emission evaluations, a practical beam current (459 pA) and stability (6%rms for 10 h) for scanning electron microscope (SEM) was obtained. The energy spread of over 200 pA of a high current electron beam generated by field emission was about the same as that of a tungsten field emission cathode. It was found that an unprecedentedly high current and high convergence electron source can be made by using diamond.

19.2: Spray‐Coating Process for Preparing CNT‐FED Cathode

AbstractA novel process for fabricating field emission display (FED) devices with spray‐coating method is proposed. Spray‐coating method can be applied to cathode and even possible for anode fabrication process. It is a fast and low cost process that is easily scaling up for large size panel. Mixing MWNT, which is synthesized by arc‐discharge, some conductive materials, and binding with solvent makes CNT mixture for spraying. Cathode is coated with CNT film by the spray process. After sintering process, it is evaluated by electron emission. This diode type CNT‐FED with spray‐coating process possessed good electron emission properties.

FABRICATION OF CARBON NANOTUBE FILM ARRAYS FOR FIELD EMISSION FLAT PANEL DISPLAY APPLICATION

The unique electron field emission properties of carbon nanotube films are promising for flat panel display application as the cold cathode. In this work, the multiwall carbon nanotube (10–102 nm in diameter, and 103–104 nm in length) film arrays (the pixel size: 50 μ m ×50 μ m ) were deposited on the patterned Ni–Si substrate from hydrocarbon precursor ( C 2 H 2/ H 2) by chemical vapor deposition at low temperature (550°C). The patterned films were characterized by scanning electron microscopy and Raman spectroscopy. The carbon nanotube film arrays exhibit good electron emission properties, e.g. low threshold emission field (below 2 V/μm), high emission current density (above 1 mA/cm2 at 10 V/μm), and high emission luminance spot density on the phosphor coated-ITO(indium tin oxide)-glass anode. These properties are good enough for high-resolution flat panel display application using carbon nanotube film arrays as the cathode.

Fabrication of Carbon Nanotube Film Arrays for Field Emission Flat Panel Display Application

The unique electron field emission properties of carbon nanotube films are promising for flat panel display application as the cold cathode. In this work, the multiwall carbon nanotube (10–102 nm in diameter, and 103–104 nm in length) film arrays (the pixel size: 50 μm ×50 μm) were deposited on the patterned Ni–Si substrate from hydrocarbon precursor (C2H2/H2) by chemical vapor deposition at low temperature (550°C). The patterned films were characterized by scanning electron microscopy and Raman spectroscopy. The carbon nanotube film arrays exhibit good electron emission properties, e.g. low threshold emission field (below 2 V/μm), high emission current density (above 1 mA/cm2 at 10 V/μm), and high emission luminance spot density on the phosphor coated-ITO(indium tin oxide)-glass anode. These properties are good enough for high-resolution flat panel display application using carbon nanotube film arrays as the cathode.

Influence of surface modifications on the electronic properties of CVD diamond films

The effects of different surface treatments, including ex-situ H 2 and H 2+O 2 plasma exposure, chromic acid treatment and in-situ vacuum annealing at elevated temperatures, on the electronic properties, particularly the electron affinity of microwave plasma-grown polycrystalline diamond films, were investigated using UV photo-electron spectroscopy (UPS) and X-ray photo-electron spectroscopy (XPS). H 2 and H 2 + O 2 plasma exposure results in a negative electron affinity (NEA) for all diamond films, independent of morphology, thickness or phase purity. An additional peak in the region of low kinetic energies of the UPS spectra correlates with plasma-generated defects that are removed by in-situ vacuum annealing for several minutes at 700 °C. NEA is not affected by this annealing procedure. Oxidation of the diamond surface by hot chromic acid results in a positive electron affinity (PEA) that correlates with a pronounced increase in film surface resistivity and complete suppression of electron emission. NEA alone is not sufficient to ensure good electron emission properties.