Electric lamp or space discharge component or device manufacturi – Process – Electrode making
Reexamination Certificate
2002-07-15
2004-12-07
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
Electrode making
C445S049000, C445S051000, C445S024000
Reexamination Certificate
active
06827624
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electron emission element for emitting electrons and a method for producing the same. In particular, the present invention relates to an electron emission element formed by using diamond particles and a method for producing the same. Furthermore, the present invention relates to an electron emission source constructed by using a plurality of electron emission elements and an image display apparatus utilizing the same.
BACKGROUND ART
In recent years, as an electron beam source replacing an electron gun for a thin display with high definition and an electron source of a vacuum microelectronic device capable of operating at a high speed, a micro-electron emission element of a micron size has been paid attention to. There are various types of electron emission elements. In general, a field emission type (FE type), a tunnel injection type (MIM type or MIS type), a surface conduction type (SCE type), or the like have been reported.
In the FE type electron emission element, a voltage is supplied to a gate electrode to apply an electric field to an electron emission portion, whereby electrons are emitted from a cone-shaped projected portion formed of silicon (Si) or molybdenum (Mo). In the MIM type or MIS type electron emission element, a layered structure including metal, an insulating layer, a semiconductor layer, and the like is formed, and electrons are injected to and passed through the insulating layer from the metal layer by utilizing a tunnel effect, whereby electrons are output from an electron emission portion. Furthermore, in the SCE type electron emission element, an electric current is allowed to flow in an in-plane direction of a thin film formed on a substrate, and electrons are emitted from a previously formed electron emission portion (generally, a microcrack portion present in a conducting region of the thin film).
Any of the above-mentioned elements are characterized in that their structures can be miniaturized and integrated by using a micro-processing technique.
In general, it is required that a material for an electron emission portion of an electron emission element has characteristics of: (1) being likely to emit electrons in a relatively small electric field (i.e., being capable of emitting electrons efficiently), (2) having good stability of an electric current to be obtained, (3) having a small change in electron emission characteristics with passage of time, and the like. However, in the above-mentioned conventional electron emission elements which have been reported, their operating characteristics are largely dependent upon the shape of an electron emission portion, and greatly change with passage of time. Furthermore, it is difficult to produce such electron emission elements with good reproducibility, and it is very difficult to control their operation characteristics.
As is understood from the above, a structure of a conventional electron emission element or a structure and a material of an electron emission portion included therein do not satisfy required characteristics sufficiently.
The present invention has been achieved so as to overcome the above-mentioned problems, and its objective is to provide: (1) an electron emission element with high stability, capable of emitting electrons efficiently, by dispersing a plurality of electron emission portions made of a particle or an aggregate of particles; (2) a high-efficiency electron emission source and an image display apparatus using the same, by disposing a plurality of the above-mentioned electron emission elements; (3) an electron emission element and an electron emission source capable of emitting electrons efficiently, in particular, by using diamond particles for an electron emission member; (4) an image display apparatus comprised of an electron emission source including a plurality of electron emission elements capable of emitting electrons efficiently and an image forming member, and a flat display for displaying a bright and stable image; (5) a production method capable of easily and efficiently conducting an important production process with respect to diamond particles used for an electron emission portion in an electron emission element of the present invention; and (6) a method for producing an electron emission element capable of producing an electron emission element having an electron emission portion, which stably operates, over a large area with ease and good reproducibility, by conducting a step of uniformly distributing diamond particles.
DISCLOSURE OF THE INVENTION
An electron emission element of the present invention includes: a pair of electrodes disposed in a horizontal direction at a predetermined interval: and a plurality of electron emission portions disposed so as to be dispersed between the pair of electrodes.
In an embodiment, the above-mentioned electron emission element further includes a substrate having an insulating surface, wherein the pair of electrodes and the plurality of electron emission portions are disposed on the insulating surface of the substrate. More specifically, electrons move from one of the electrodes to the other electrode so as to hop through the plurality of electron emission portions by a transverse electric field generated between the pair of electrodes.
In another embodiment, the above-mentioned electron emission element further includes a conductive layer disposed between the pair of electrodes and electrically connected thereto, wherein the plurality of electron emission portions are disposed on the conductive layer. For example, the pair of electrodes can be provided as partial regions on ends of the conductive layer. Alternatively, the pair of electrodes and the conductive layer are made of different materials. In any case, electrons move from one of the electrodes to the other electrode by an electric current flowing through an inside of the conductive layer in an in-plane direction.
The conductive layer can be heated when an electric current flows through an inside of the conductive layer in an in-plane direction.
An amount of electron emission can be modulated by controlling an amount of the electric current flowing through an inside of the conductive layer in an in-plane direction.
Preferably, a dispersion density of the plurality of electron emission portions is about 1×10
9
/cm
2
or more.
Preferably, the plurality of electron emission portions are independent relative to one another without coming into contact with each other.
Each of the plurality of electron emission portions is made of a particle of a predetermined material or an aggregate of the particles.
Preferably, an average particle diameter of the particles included in each of the plurality of electron emission portions is about 10 &mgr;m or less.
The predetermined material is diamond or a material mainly containing diamond.
The above-mentioned electron emission element includes a structure in which atoms on an outermost surface of the diamond or the material mainly containing diamond are terminated by binding to hydrogen atoms. Preferably, an amount of the hydrogen atoms binding to the atoms on the outermost surface is about 1×10
15
/cm
2
or more.
The diamond or the material mainly containing diamond has crystal defects. Preferably, a density of the crystal defects is about 1×10
13
/cm
3
or more.
The diamond or the material mainly containing diamond has a non-diamond component which is less than about 10% by volume.
The particles of the predetermined material are diamond particles produced by crushing a diamond film formed by a vapor-phase synthesis method. For example, the vapor-phase synthesis method is a plasma jet CVD method.
The conductive layer is a metal layer or an n-type semiconductor layer.
Preferably, a thickness of the conductive layer is about 100 nm or less.
Preferably, an electric resistance of the conductive layer is higher than an electric resistance of the electron emission portions.
An electron emission source includes a plurality of electron emission elements arranged in a predete
Deguchi Masahiro
Kitabatake Makoto
Kurokawa Hideo
Sato Toshifumi
Shiratori Tetsuya
Matsushita Electric - Industrial Co., Ltd.
Patel Nimeshkumar D.
Renner , Otto, Boisselle & Sklar, LLP
Santiago Mariceli
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