KR20110060236A - Cathode structure of electron emitting device - Google Patents

Abstract

PURPOSE: A cathode structure of an electron emission device is provided to simplify a manufacturing process by performing a laser process or a mechanical process for forming a substrate having a concavo-convex part. CONSTITUTION: A cathode(200) emits electronics. An anode(100) is arranged on an upper part of the cathode. The cathode part includes a substrate(210) having a concavo-convex part formed on a surface thereof. The cathode part includes an emitter(230) which is formed on the upper surface of the substrate. The concavo-convex part includes a protrusive part and a concave part.

Description

Cathode structure of electron emitting device

The present invention relates to a cathode structure of an electron emitting device, and more particularly, to a cathode structure of an electron emitting device capable of improving current density of electrons emitted from an emitter even at a low electric field due to irregularities formed on a substrate of the cathode. It is about.

A typical electron emitting device based X-ray tube has a cathode part and an anode part installed inside a vacuum-sealed bulb, and electrons generated at the cathode part are accelerated by a high voltage applied between the cathode part and the anode part and collide with the target of the anode part. X-rays are generated.

Thus, as a typical representative X-ray tube which generate | occur | produces an electron in a cathode part, the X-ray tube which has a hot electron emission cathode structure which generates an electron by heating a tungsten filament is mentioned.

However, in the case of X-ray tube using the hot electron emission phenomenon, due to the heat problem when heating the filament, the degree of vacuum decreases due to the degassing and internal heating generated in the filament and the connecting portion, and the evaporated tungsten is heated on the target surface and the vacuum chamber. Deposition in the inner wall, such as lowering the high-pressure insulation and reducing the amount of transmitted radiation occurs.

Recently, studies on X-ray tubes using field emission phenomenon in which electrons are emitted beyond the potential barrier (work function) on a solid surface when a high electric field is applied instead of the hot electron emission phenomenon have been actively conducted.

In particular, studies on X-ray tubes using carbon nanotubes (CNTs), which have electron emission voltages of 1 to 3 V / µm, which are several orders of magnitude lower than other metal tips, are being conducted. .

CNT hexagonal shape consisting of six carbons connected to each other to form a long tubular shape, the tube diameter is only a few tens of nanometers, forming a high aspect ratio structure.

It is composed of carbon element, which not only has low work function, but also has high aspect ratio, which is advantageous for electron emission because the threshold electric field of field emission is lower than other field emission sources.

Since several currents are generated in one strand of carbon nanotube tip (N.de Jonge, et. have.

By using CNTs as field emission devices, electron emission voltages can be significantly lowered, resulting in lower driving voltages than using field emission devices such as spin-type tips or silicon tips.

The reason why the field emission voltage of CNTs is low is because the diameter is so small that the field enhancement factor (Field Enhancement Factor) is so large that the emission field (Turn-on Field) is low as 1 ~ 3V / ㎛.

1 is a view for explaining the X-ray tube using a CNT emitter according to the prior art.

Referring to FIG. 1, in the X-ray tube using the conventional CNT emitter, when electrons are emitted from the CNT emitter 3 formed in the cathode part 5 according to the induction of electron emission of the grid electrode 7, the emitted electrons are emitted. Is focused by the focusing lens 8, electrons collide with the anode 9, and X-ray L is generated.

That is, the grid electrode 7 for inducing electron emission is provided between the anode portion 9 and the cathode portion 5 to have a tripolar structure.

However, in the X-ray tube using the conventional CNT emitter, the substrate 1 of the cathode portion 5 is formed with a flat surface, from the CNT emitter 3 formed on the flat substrate 1. There is a problem that the electron emission characteristics are not very good.

Therefore, in order to improve the field emission characteristics, studies are being conducted to form a pattern on the CNT emitter 3 formed on the substrate 1, and fine patterning of the CNT emitter 3 on the substrate 1 is performed. As a method, the following method can be used.

First, a CNT paste is prepared by dispersing CNT powder, an organic binder, a photosensitive material, a monomer, and nano-sized metal particles in a solvent, and then applying the prepared CNT paste onto an electrode formed on the substrate. Subsequently, after exposing and finely patterning the CNT paste applied on the electrode, the fine patterned CNT paste is fired to treat the surface of the CNT paste so that the surface of the fired CNT paste is activated.

However, such a method for forming a pattern on a CNT emitter has a problem of undergoing complicated semiconductor processing.

The present invention has been made to solve the above problems, it is to be able to maximize the discharge current per unit area emitted from the emitter by the unevenness formed on the substrate of the cathode portion.

Another object of the present invention is to provide a cathode structure of an electron emission device having improved field emission characteristics and excellent electrical characteristics.

It is also an object of the present invention to provide a cathode structure of an electron emitting device which is simple to manufacture by forming a substrate having irregularities through a laser or mechanical processing with a simple process.

In order to achieve the above object, the present invention, the negative electrode portion for emitting electrons and an anode portion disposed on the cathode portion, the electron emission device comprising a, the cathode portion, the substrate and the substrate of the irregularities formed on the surface of the substrate A cathode structure of an electron emission device, characterized in that it comprises an emitter formed on top.

Preferably, the irregularities may include protrusions and recesses.

In addition, the unevenness formed on the surface of the substrate may be formed in the form of a checkerboard.

Furthermore, the unevenness may include a cylindrical protrusion and a ring-shaped recess surrounding the protrusion.

The unevenness may include a cylindrical recess and a ring protrusion surrounding the recess and a ring recess surrounding the protrusion.

In addition, the recess may be formed of at least two holes.

Wherein the emitter is preferably formed of any one of CNT, carbon films (Carbon films), carbon tubular nanocoils (Carbon Tubule Nanocoils), aluminum nitride nanorods (Aluminum nitride nanorods).

Furthermore, the CNT emitter may be coated on the substrate, in particular, preferably coated on the protrusion, and electrons are preferably emitted from the CNT emitter formed on the protrusion.

On the other hand, the present invention, the negative electrode portion for emitting electrons and the positive electrode portion disposed on the cathode portion; wherein the cathode portion, the substrate and the substrate having irregularities formed on the surface by laser processing It is a cathode structure of an electron emission device, characterized in that it comprises an emitter formed on top.

Preferably, the unevenness may include a protrusion and a recess.

In addition, the unevenness formed on the surface of the substrate may be formed in the form of a checkerboard.

And the emitter is preferably formed of any one of CNT, carbon films (Carbon films), carbon tubular nanocoils (Carbon Tubule Nanocoils), aluminum nitride nanorods (Aluminum nitride nanorods).

In addition, the CNT emitter may be coated on the substrate, particularly preferably coated on the protrusion, and electrons are preferably emitted from the CNT emitter formed on the protrusion.

According to the present invention, there is an effect that can improve the current density of electrons emitted from the emitter even in a low electric field by the unevenness formed on the substrate of the cathode portion.

In addition, in the present invention, by forming a substrate having irregularities through laser or mechanical processing, it is possible to provide a cathode structure of an electron emitting device which is simple to manufacture.

Moreover, according to the present invention, since it can be directly applied to the current commercially available electron emitting device without any structural change, there is an advantageous effect in terms of cost.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments of the present invention described below are provided to enable those skilled in the art to more easily understand the present invention, and the scope of the present invention is not limited to the described embodiments.

Hereinafter, an example of an X-ray tube, which is a representative example of an electron emission device, will be described as an embodiment.

However, the present invention is not limited to the X-ray tube, but it is to be clarified that the present invention can be applied to any field emission device having a cathode structure according to the present invention.

2 to 10, a preferred embodiment of the present invention will be described.

Referring to FIG. 2, FIG. 2 is a cross-sectional view of an X-ray tube having a structure of a cathode part having irregularities according to the present invention.

As shown, the structure of the X-ray tube according to the present invention includes a cathode portion 200 in which an emitter (shown in FIG. 3) as an electron emission source is formed.

Here, the cathode part 200 includes a substrate 210 having an emitter formed thereon, and the substrate 210 is preferably made of stainless steel to which voltage is easily applied.

A first insulating casing 330 is formed around the substrate 210 to insulate the cathode part 200, and the electron beam generated from the cathode part 200 is an anode in the first insulating casing 330. An opening 340 may be formed to face the portion 100.

Here, the anode part 100 is a portion where electrons directly collide with each other, and may be formed of a material such as tungsten or copper having good generation efficiency of X-rays.

The first insulating casing 330 is preferably made of a material such as ceramic that is good for insulation and can maintain a degree of vacuum in a vacuum state.

In addition, a grid electrode 500 for emitting electrons from the cathode 200 is formed on the cathode 200, and the fold-beam converging unit 350 for focusing the emitted electrons on the anode 100. May be formed on the grid electrode 500.

The electron beam focusing unit 350 is formed by sandwiching a plurality of electron focusing lenses 300 and a plurality of electron focusing lenses 300 for sequentially focusing the electron beam passing through the grid electrode 500 at a micro level. The second insulating casing 310 may include a plurality of insulating layers 320 for insulating the plurality of electron focusing lenses 300 and a second insulating casing 310 formed to surround the remaining portion except for the opening 340 through which the electron beam passes. Can be.

In this case, the electron focusing lenses 300 may be applied in plural numbers by varying their inner diameters.

Therefore, the area focused on the anode part 100 can be efficiently and easily reduced by receiving discontinuously receiving a force received by the electrons passing through the electron focusing lenses 300 within a predetermined distance.

Here, the electron focusing lenses 300 of the electron beam focusing unit 350 are made of stainless steel, which is easy to apply voltage, and the insulating layers 320 of the electron beam focusing unit 350 are good for insulation and have a vacuum degree in a vacuum state. It is preferred to be made of a material such as a sustainable ceramic or the like.

In addition, a grid electrode 500 is formed between a first insulating casing 330 and the electron beam focusing unit 350 and is made of a metallic material having a tungsten mesh and capable of applying a high voltage.

A substrate support 360 for supporting the substrate 210 is provided below the substrate 210 used in the present invention.

Meanwhile, the anode part 100, the cathode part 200, and the electron beam focusing part 350 are accommodated and protected in the housing 20, and the housing 20 is made of Pyrex, glass, ceramic, or stainless steel capable of maintaining a vacuum. It is preferable to be produced by either.

In addition, the support 600 may serve to fix and support the cathode 200 and the electron beam focusing unit 350 in the housing 20. The support 600 may be formed of stainless steel or ceramic having high strength.

As shown, the housing 20 is equipped with a vacuum pump 30 for maintaining the interior in a vacuum state, which vacuum pump 30 maintains the vacuum whenever necessary or in real time over time It can solve the problem of naturally occurring vacuum destruction.

In FIG. 2, reference numeral 10 denotes a window through which X-rays are emitted, and may be made of quartz glass, ordinary glass, non-window (Be window), and the like, and reference numeral 101 denotes power of the anode part 100. 50 and 60 show connection terminals and a power supply line for applying a voltage to the grid electrode 500 and the electron focusing lenses 300, respectively.

Here, the power supply line 101 preferably uses a material such as tungsten or copper having good thermal conductivity in order to conduct heat generated when electrons collide with the surface of the anode part 100 to the outside.

In the present invention configured as described above, as shown in FIG. 2, the anode portion 100 is mounted on the upper portion, and when the power supply line 101 is operated in a state in which it is connected to the anode portion 100, the substrate 210 is connected to the substrate 210. As the electrons are emitted from the formed emitter, the electron beam passes through the electron focusing lenses 300 to the anode part 100.

This results in a maximum micro-level focusing area, enabling high resolution of the final image obtained.

Referring to FIG. 3, FIG. 3 is an exploded perspective view schematically illustrating main components of an X-ray tube having a structure of a cathode part having irregularities according to the present invention.

Hereinafter, the same reference numerals as in the drawing shown in FIG. 2 denote the same members having the same function.

As shown in FIG. 3, the structure of the X-ray tube according to the present invention includes a cathode part 200, and the cathode part 200 has a substrate 210 having irregularities (shown below in FIG. 5) formed on a surface thereof. ).

In addition, an emitter 230 that is used as an electron emission source by generating an electron beam is formed on the substrate 210.

Here, the emitter 230 is preferably formed of CNTs, and in addition to the CNTs, the emitter 230 may be formed of any one of carbon films, carbon tubular nanocoils, and aluminum nitride nanorods. Can be.

When the CNT is used as the emitter 230, there are various methods of forming the CNT on the substrate 210.

That is, after forming a catalyst on the substrate 210, vertical growth of the CNT by chemical vapor deposition (CVD), spin coating (Spin coater) after mixing the CNT prepared by various synthetic methods with a liquid solvent Or a method of forming using a spray or inkjet, or mixing a viscous polymer resin with a solvent, a filler, and other additives with CNT to make a paste and then screen printing.

The shape of the substrate 210 is preferably formed in a disk shape, but there is no restriction in the shape of a triangle, a square, a pentagon, and the like.

A grid electrode 500 for emitting electrons 400 is formed on the substrate 210. The grid electrode 500 has a thin opening and a large opening amount so as to facilitate extraction of the electrons 400. And tungsten or stainless steel.

The electrons 400 passing through the grid electrode 500 are focused through the electron focusing lenses 300 and are directed toward the anode part 100.

The electrons 400 reaching the anode part 100 collide with the anode part 100 to emit X-rays.

Referring to FIG. 4, FIG. 4 is a cross-sectional view of the cathode illustrated in FIG. 3.

An emitter 230 is formed on the substrate 210, wherein the emitter 230 is formed of CNTs, carbon films, carbon tubular nanocoils, and aluminum nitride nanorods. ) Can be formed of any one.

When the emitter 230 is formed of CNT, various additives and CNT powder may be blended to form a paste and then screen-printed on the substrate 210 to form the emitter 230.

The emitter 230 is an electron emission source, and an electron beam 450 is formed from the emitter 230 and directed to the anode part 100.

Referring to FIG. 5, FIG. 5 is a cross-sectional view illustrating a shape in which irregularities are formed on a substrate of a cathode part according to the present invention.

As shown in FIG. 5, unevenness is formed in the substrate 210, and the unevenness formed in the substrate 210 has a protrusion 215 and a recess 217.

The unevenness formed on the substrate 210 may be formed in any form as long as it has an electric field strengthening effect.

Therefore, as described in FIG. 4, when the CNT paste is screen printed onto the substrate 210, the CNT emitter 230 having a thickness of several micrometers is mainly coated on the protrusion 215 of the substrate 210.

That is, the portion where the electrons are emitted is limited to the emitter 230 formed on the protrusion 215 of the substrate 210, so that an electric field is strongly formed in the emitter 230 formed on the protrusion 215. The number of electrons emitted is increased.

Thus, a high current density electron beam can be obtained even at a low electric field.

Here, the unevenness is formed through laser or mechanical processing, and it is possible to provide a substrate that is simple to manufacture without the need for a complicated semiconductor process to pattern the conventional CNT emitter itself.

Referring to FIG. 6, FIG. 6 is a plan view and a perspective view of a cathode part including a substrate on which a checkerboard irregularities are formed according to a first embodiment of the present invention.

As shown in FIG. 6, checkerboard irregularities are formed on the substrate 210 through laser processing.

That is, a plurality of rows of recesses 217 are formed horizontally and vertically through a laser to form a checkered protrusion 215.

7 is a photograph and SEM image of a substrate formed through laser processing according to the above description.

An experiment was performed to measure the current density according to the electric field with the substrate 210 formed through the laser processing.

In the present embodiment, CNT is used as the emitter 230, and CNT paste is formed by screen printing on the substrate 210.

Here, the CNT for use as the emitter 230 used Thin-MWCNT (Multi Wall CNT) having a diameter of about 3 to 5 nm, where "Thin" is thin or thick depending on the number of walls of the CNT. Generally, the number of months with less than 5 is classified as thin.

Various additives are used to form a viscous binder and CNT powder is added and mixed therein to form a CNT paste, where 1 wt.% Of CNT is added.

Next, a cylindrical stainless steel substrate having a height of 10 mm and a diameter of 10 mm was fixed to a jig having holes of the same height and diameter, and the CNT paste was screen-printed four times to form a sufficient thickness thereon. .

After flattening for 20 minutes after the screen printing, and dried for 20 minutes at 80 ℃ to remove the organic solvent, after firing 20 minutes at 420 ℃ in the air atmosphere to remove the remaining organic matter and organic solvent, using an adhesive tape And pressed through the physical force on the CNT emitter 230.

This is to form the CNT paste formed horizontally on the substrate 210 in the process of hardening through the firing process to be perpendicular to the substrate 210.

In addition, the anode part 100 was used by coating a phosphor on ITO (Indium Thin Oxide) to obtain a field emission image (see FIGS. 8 and 9).

The gap between the cathode part 200 and the anode part 100 was maintained at 530 μm, and the basic pressure of the vacuum chamber was maintained at 5 × 10 ⁻⁷ torr or less.

In addition, a DC voltage was applied to the anode part 100 while the cathode part 200 was grounded, and voltage application and current measurement were all controlled by a computer in real time.

8 to 10, Figure 8 is a photograph showing a field emission image of a conventional flat substrate, Figure 9 is an electric field of the substrate having a checkerboard-shaped irregularities formed by laser processing according to the first embodiment of the present invention It is a photograph showing an emission image, and FIG. 10 is a graph measuring current density according to an electric field using the substrates of FIGS. 8 and 9.

Comparing FIG. 8 and FIG. 9, it can be seen that the substrate formed with the checkerboard irregularities by laser processing according to the first embodiment of the present invention of FIG. 9 shows a higher current density even at a lower voltage.

For example, in each of the third photographs of FIGS. 8 and 9, the conventional flat substrate of FIG. 8 shows a current density of 5.00 × 10 ⁻⁴ A at 1620 V, but FIG. 9 shows the first embodiment of the present invention. In the case of the board formed with the checkerboard irregularities by laser processing according to the example it can be seen that a high current density of 2.38 × 10 ^-3 A even at a low voltage of 1200V.

In other words, it can be seen that in the case of the negative electrode having irregularities on the surface of the substrate through laser processing, the current density is high even in a low electric field due to the large field strengthening effect.

FIG. 10 is a graph measuring current density according to an electric field using the substrates of FIGS. 8 and 9, wherein a substrate having a checkerboard irregularities formed by laser processing according to a first embodiment of the present invention (400 μm on a graph) , 200 μm and 60 μm patterned) show high current density even at low electric fields when compared to flat substrates (denoted as flat substrates on graphs).

Hereinafter, a second embodiment of the present invention will be described with reference to FIG. 11.

In the second embodiment, only the characteristic parts distinguished from the first embodiment will be described and described for convenience of description, and the same components will be described with the same reference numerals.

11 is a plan view and a perspective view of a cathode part including a substrate having a plurality of holes formed on a surface thereof according to a second exemplary embodiment of the present invention.

In the present embodiment, the recess 217 including the plurality of holes 219 is formed in the substrate 210 through laser or mechanical processing.

Accordingly, portions other than the plurality of holes 219 become protrusions 215, and an emitter 230 is formed on the substrate 210 including the recesses 217 and the protrusions 215, wherein the emitters 230 are formed. Emitter 230 is formed in protrusion 215 of substrate 215.

That is, the portion from which electrons are emitted is limited to the emitter 230 formed on the protrusion 215 of the substrate 210, so that an electric field is strongly formed in the emitter 230 formed on the protrusion 215. The number of electrons emitted is increased.

Thus, a high current density electron beam can be obtained even at a low electric field.

Hereinafter, a third embodiment of the present invention will be described with reference to FIG. 12.

In the third embodiment, only the characteristic parts distinguished from the first and second embodiments will be described and described, and for the convenience of description, the same elements will be described with the same reference numerals.

12 is a plan view and a perspective view of a cathode part including a substrate having a cylindrical protrusion according to a third exemplary embodiment of the present invention.

In the present embodiment, the first protrusion 215 having a cylindrical shape is formed in the center of the substrate 210 through laser or mechanical processing.

Accordingly, a ring-shaped recess 217 is formed to surround the first protrusion 215, and a ring-shaped second protrusion 215 is formed to surround the ring-shaped recess 217.

Here, the emitter 230 is formed only on the circular first protrusion 215.

That is, the portion where the electrons are emitted is limited to the emitter 230 formed on the first protrusion 215 of the substrate 210, so that an electric field is applied to the emitter 230 formed on the protrusion 215. The number of electrons that are strongly formed and emitted increases.

Thus, a high current density electron beam can be obtained even at a low electric field.

Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. 13.

In the fourth embodiment, only characteristic parts distinguished from the first to third embodiments will be extracted and described, and for the convenience of description, the same elements will be described with the same reference numerals.

FIG. 13 is a plan view and a perspective view of a cathode part including a substrate having a ring-shaped protrusion according to a fourth exemplary embodiment of the present invention.

In the present embodiment, a ring-shaped first protrusion 215 is formed in the center of the substrate 210 through laser or mechanical processing.

Accordingly, a first recess 217 having a cylindrical shape is formed in the first protrusion 215, and a second recess of a ring shape surrounds the first protrusion 215 outside the first protrusion 215. A portion 217 is formed, and a second protrusion 215 surrounding the second recess 217 is formed outside the second recess 217.

Here, the emitter 230 is formed only on the ring-shaped first protrusion 215.

That is, the portion where the electrons are emitted is limited to the emitter 230 formed on the first protrusion 215 of the substrate 210, so that an electric field is applied to the emitter 230 formed on the protrusion 215. The number of electrons that are strongly formed and emitted increases.

Thus, a high current density electron beam can be obtained even at a low electric field.

As mentioned above, while the present invention has been mentioned that the present invention is applied to an X-ray tube having an emitter-coated uneven substrate, the present invention is applied to any field emission device having an emitter-formed uneven substrate at a cathode part. It will be appreciated that this may apply.

In addition, the above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains various modifications and variations without departing from the essential characteristics of the present invention. . Therefore, the embodiments described in the present invention are not intended to limit the technical idea of the present invention but to explain, and the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents thereof should be construed as being included in the scope of the present invention.

1 is a view for explaining the X-ray tube using a CNT emitter according to the prior art,

2 is a cross-sectional view of the X-ray tube having a structure of the negative electrode portion is formed with unevenness according to the present invention,

Figure 3 is an exploded perspective view schematically showing the main parts of the X-ray tube having a structure of the negative electrode portion formed with unevenness according to the present invention,

4 is a cross-sectional view of the negative electrode shown in FIG.

5 is a cross-sectional view showing the appearance of irregularities on the substrate of the negative electrode portion according to the present invention,

6 is a plan view and a perspective view of a cathode part including a substrate on which a checkerboard irregularities are formed according to a first embodiment of the present invention;

7 is a photograph of the substrate and the SEM image formed by laser processing according to the above description,

8 is a photograph showing a field emission image of a conventional flat substrate,

9 is a photograph showing a field emission image of a substrate on which a checkerboard-shaped irregularities are formed by laser processing according to the first embodiment of the present invention.

FIG. 10 is a graph measuring current density according to an electric field using the substrates of FIGS. 8 and 9.

11 is a plan view and a perspective view of a cathode part including a substrate having a plurality of holes formed on a surface thereof according to a second embodiment of the present invention;

12 is a plan view and a perspective view of a cathode part including a substrate having a circular protrusion, according to a third exemplary embodiment of the present invention;

13 is a plan view and a perspective view of a cathode including a substrate having a ring-shaped protrusion according to a fourth embodiment of the present invention.

<Description of Major Symbols in Drawing>

100: anode part, 200: cathode part

300: electron beam focusing lenses, 400: electrons

450: electron beam, 210: substrate,

215: protrusion, 217: recess

230: emitter

Claims (17)

A cathode part emitting electrons; And An electron emission device comprising; an anode portion disposed above the cathode portion. The cathode portion, the substrate is formed with irregularities on the surface; And an emitter formed on an upper portion of the substrate. The method of claim 1, The irregularities structure of the cathode portion of the electron emission device, characterized in that the projection and the recess portion. The method according to claim 1 or 2, The unevenness formed on the surface of the substrate is formed in the form of a checkerboard, the cathode structure of the electron emission device, characterized in that. The method of claim 2, The unevenness, the cathode structure of the electron emitting device, characterized in that it comprises a cylindrical projection and a ring-shaped recess surrounding the projection. The method of claim 2, The concave-convex structure includes a cylindrical recessed portion, a ring-shaped protrusion surrounding the recessed portion, and a ring-shaped recessed portion surrounding the protrusion. The method of claim 2, The concave portion has a cathode portion structure of an electron emitting device, characterized in that it comprises at least two holes. The method of claim 1, The emitter is a cathode structure of the electron emission device, characterized in that formed of any one of CNT, carbon films (Carbon films), Carbon Tubule Nanocoils, Aluminum nitride nanorods (Aluminum nitride nanorods). The method of claim 7, wherein And the CNT emitter is coated on the substrate. The method of claim 8, And the CNT emitter is coated on the protrusion part. 10. The method of claim 9, The cathode structure of the electron emission device, characterized in that electrons are emitted from the CNT emitter formed in the protrusion. A cathode part emitting electrons; And An electron emission device comprising; an anode portion disposed above the cathode portion. The cathode portion, the substrate formed with irregularities on the surface by laser processing; And an emitter formed on an upper portion of the substrate. The method of claim 11, The irregularities structure of the cathode portion of the electron emission device, characterized in that the projection and the recess portion. 13. The method according to claim 11 or 12, The unevenness formed on the surface of the substrate is formed in the form of a checkerboard, the cathode structure of the electron emission device, characterized in that. The method of claim 11, The emitter is a cathode structure of the electron emission device, characterized in that formed of any one of CNT, carbon films (Carbon films), Carbon Tubule Nanocoils, Aluminum nitride nanorods (Aluminum nitride nanorods). The method of claim 14, And the CNT emitter is coated on the substrate. The method of claim 15, And the CNT emitter is coated on the protrusion part. The method of claim 16, The cathode structure of the electron emission device, characterized in that electrons are emitted from the CNT emitter formed in the protrusion.

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