JP2000067740A - Structure of metal oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for increasing electron emission current value in a low electric field, particularly a structure useful as a cold cathode element. SOLUTION: In this structure, a part of or entire surface of a metal oxide made substrate material having projections is covered with conductive material, and the tips of the projections are covered with one or more kinds of electron emission material. Preferably the structure has the projections with density of 0.01-10,000 in number per 10 μm×10 μm in area on the substrate material. In particular, this structure is optimal for a cold cathode element application. This structure can increase electron emission current value in a low electric field, and particularly is preferably used for the cold cathode element application.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal oxide structure, mainly a cold cathode device.

[0002]

2. Description of the Related Art Metal oxides are used for electronic materials such as ceramic capacitors, actuators, light wavelength conversion elements, laser oscillation elements, and cold cathode elements. Among them, cold-cathode devices have a wide viewing angle, can supply electrons by suppressing heat generation, are capable of supplying electrons, and have low power consumption. The use is spreading. However, since the current cold cathode device has a low electron emission current value, it is necessary to apply a large electric field between the cold cathode device and the phosphor at the time of use, and there has been a problem that a heat generation amount or power consumption increases.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a structure having a large electron emission current value with a small electric field, particularly a structure useful as a cold cathode device.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies on a structure effective for a cold cathode device or the like, which has a large electron emission current value with a small electric field, particularly a cold cathode device. By making a substrate with many protrusions in a small area, attaching electrodes to it, and coating the tips of the protrusions with a substance having an electron current density of a certain value or more, it is effective for cold cathode devices etc. It has been found that an excellent structure can be obtained, and the present invention has been accomplished.

That is, according to the present invention, (1) a part or the whole of the surface of a substrate made of a metal oxide and having a projection is covered with a conductive substance, and the tip of the projection is formed of one or more kinds of easily. The structure covered with the electron-emitting substance, (2) the protrusions are 0.01 μm per 10 μm × 10 μm area on the substrate.
The structure according to (1), wherein the structure is present at a density of 10,000 to 10,000.
(3) The projection has a cross-sectional circle equivalent diameter of 0.01 to 1000.
(1) The rod according to (1) or (2), which is a rod-shaped object having a length of 0 μm and a length / cross-section circle-converted diameter ratio of 1 or more, and (4) the central axes of the protrusions are parallel to each other. (3) The structure according to the above,
(5) The structure according to any one of (1) to (4), wherein the base material is a metal oxide single crystal, and (6) the metal oxide crystals constituting the projection are parallel to each other on the base material. And the crystal axes are grown in the same direction.
(5) The structure according to (5), wherein the easy electron-emitting substance covering the tip of the protrusion is nickel, iron, stainless steel, MgO,
(1) The structure according to (1) to (6), which is one or more substances selected from a carbon thin film; (8) the structure according to (1) to (7), in which an external electrode is attached to a conductive substance; 9) (1)-
(8) A cold cathode device comprising the structure according to (8),

Hereinafter, the present invention will be described in detail. The projection in the present invention refers to an object having a mountain-shaped raised portion, a lump or a rod-like structure. The size of the protrusion is preferably such that the cross-sectional circle-converted diameter is 0.01 to 10000 μm, more preferably 0.05 to 100 μm.
m, most preferably 0.1 to 10 μm. As for the shape of the projection, the ratio of the length / cross-sectional diameter in circle, that is, the aspect ratio is 1 or more, preferably 3 or more, and more preferably 5 or more. If the aspect ratio is too small, the effect of increasing the surface area due to the protrusions will not appear. The higher the aspect ratio, the more the effect of the projections appears. However, if the aspect ratio is too high, it becomes difficult to maintain the strength of the structure when coated with a conductive material, and it is necessary to reinforce the structure with a resin or the like.

[0007] The cross section referred to here is 1 / the length of the projection.
2 shows the surface at the position 2. In addition, the length of the protrusion here refers to a length from a position where the protrusion substantially protrudes from the surface to a vertex of the protrusion. The length depends on the intended use and is not limited.
From a practical viewpoint, the thickness is preferably 0.1 to 10000 μm, more preferably 1 to 1000 μm, and still more preferably 10 to 5 μm.
00 μm. The three-dimensional shape of the protrusion is not particularly limited, but is preferably a rod-like shape, and more preferably a shape in which the diameter of the tip is smaller than the diameter of the cross section. Specifically, the diameter of the root portion of the projection is small, and once the diameter increases as it goes to the tip, the diameter gradually decreases again.The diameter increases as it goes from the root of the projection to the tip. Examples include those that gradually decrease, and those that take a shape like a pyramid or a truncated pyramid, a cone or a truncated cone, or a hemisphere from a position near the tip. In this case, if the diameter of the tip is smaller than the diameter of the cross section, other shapes may be used.

[0008] The size of the tip of the projection is not particularly limited because it is also related to the shape of the tip. However, when the shape of the tip is a plane, the ratio of the circle-converted diameter of the tip to the circle-converted diameter of the cross section is 1. It is preferably less than 0.5, more preferably 0.5 or less, even more preferably 0.3 or less. When the shape of the tip is a line, the ratio of the length of the tip / the circle-converted diameter of the cross section is 1
It is preferably less than 0.5, more preferably 0.5 or less, even more preferably 0.3 or less. When the shape of the tip is a point, the ratio of the length of the tip to the circle-converted diameter of the cross section is 0.
Is more preferable. The projections preferably have their central axes parallel to each other, and more preferably have a surface in which a plurality of projections are parallel to each other.
The ratio of protrusions on the surface is 10 μm × 10
The number is preferably 0.01 to 10000, more preferably 1 to 1000, and still more preferably 10 to 500 per μm area.

The substrate in the present invention comprises a metal oxide having protrusions. In the present invention, the metal oxide is a metal whose group in the periodic table is Group 1 except for hydrogen, Group 2 except for boron, Group 14 except for carbon, Group 15 except for nitrogen, phosphorus and arsenic, Po and 3, 4, 5, 6, 7, 8, 9,
These are oxides that are elements belonging to Groups 10, 11, and 12. Examples of the metal species include Li, Na, K, Rb,
Cs, Be, Mg, Ca, Sr, Ba, Al, Ga, I
n, Tl, Si, Ge, Sn, Pb, Sb, Bi, P
o, Sc, Y, La, Ce, Pr, Nd, Pm, Sm,
Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, L
u, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo,
W, Mn, Tc, Re, Fe, Ru, Os, Co, R
h, Ir, Ni, Pd, Pt, Cu, Ag, Au, Z
n, Cd, Hg, etc., of which Be, N
a, Mg, Al, Si, K, Ca, Ti, Cr, Mn,
Fe, Co, Ni, Zn, Ga, Ge, As, Y, Z
r, Cd, In, Sn, Sb, Cs, Ba, Pb, B
i, Th, etc. are more preferable, and Mg, Ti, Ba,
Sr, K, Ta, Nb, Li, Pb, Zr, In, Sn
Is particularly preferred. These metals can be used alone or in combination of two or more. For example, barium titanate, SrTiO ₃ , PZT and the like can be mentioned. Further, an alkali metal and another metal can be used in combination. For example, Ta, Nb and or KTaO ₃ in combination alkali metal or the like, to form a composite oxide such as NbLiO _3, can be a metal oxide.

The metal oxide may be basically crystalline or amorphous, but is preferably crystalline. Crystalline is one or more single crystals, polycrystalline, or one or more semi-crystalline materials having both an amorphous part and a crystalline part, or a mixture thereof. Good. Particularly preferably, it is a single crystal. In the case of using two or more types of metal oxides, the metal oxides may be mixed to form a single layer, or layers of metal oxides having different compositions may be stacked. The projections and the metal oxide species of the substrate portion excluding the projections may be the same or different. Preferably they are of the same type.

The shape of the substrate excluding the protrusions may be any shape as long as it has a substantially flat surface and / or a curved surface.
A plate shape having a large surface area with respect to the thickness is more preferable. Further, in the case of a plate shape, it is preferable that the surface having the protrusion has the largest area as compared with other surfaces. The size of the surface having the projections is not particularly limited, but in the case of a plate shape, the thickness is preferably from 0.01 mm to 100 mm from a practical viewpoint, more preferably from 0.02 mm to 100 mm.
It is 50 mm, most preferably 0.05 mm to 10 mm. The base material made of a metal oxide is formed from a metal compound that forms a metal oxide by reacting with oxygen, water, ammonia, or the like. The metal compound in the present invention is not particularly limited as long as it has a metal in a metal oxide and reacts with oxygen, water, ammonia and the like to form an oxide.

Examples of such a metal compound include alkoxides in which the hydrogen of an alcohol hydroxyl group is substituted with a metal for the metal or metal-like element, acetylacetone, ethylenediamine, bipiperidine, bipyrazine for the metal or metal-like element. Cyclohexanediamine, tetraazacyclotetradecane, ethylenediaminetetraacetic acid, ethylenebis (guanide), ethylenebis (salicylamine), tetraethylene glycol, aminoethanol, glycine, triglycine, naphthyridine, phenanthroline, pentanediamine, pyridine,
One or two ligands selected from salicylaldehyde, salicylideneamine, porphyrin, thiourea, etc.
Fe, Cr, Mn, Co, Ni, Mo, V, W, having various kinds of complexes having a carbonyl group as a ligand
Various metal carbonyls such as Ru, carbonyl group, alkyl group, alkenyl group, phenyl or alkylphenyl group, olefin group, aryl group, conjugated diene group including cyclobutadiene group, and cyclopentadienyl group. Various metal compounds and metal halide compounds having one or more ligands selected from trienyl groups such as a dienyl group, a triene group, an arene group, a cycloheptatrienyl group and the like can be used. . Also, metal complexes can be used. Among them, complexes such as acetylacetone and alkoxides are more preferably used.

The complex in the present invention includes β-
Distribution of diketones, ketoesters, hydroxycarboxylic acids or salts thereof, various Schiff bases, ketoalcohols, polyvalent amines, alkanolamines, enol active hydrogen compounds, dicarboxylic acids, glycols, ferrocenes, etc. Compounds in which one or two or more ligands are bonded are exemplified.

Specific examples of the compound serving as a ligand of the complex used in the present invention include, for example, acetylacetone, ethylenediamine, triethylenediamine, ethylenetetramine, bipiperidine, cyclohexanediamine, tetraazacyclotetradecane, ethylenediaminetetraacetic acid, ethylenebis (Guanide), ethylenebis (salicylamine), tetraethyleneglycol, diethanolamine, triethanolamine, tartaric acid, glycine, triglycine, naphthyridine, phenanthroline, pentanediamine, salicylaldehyde, catechol, porphyrin, thiourea, 8-hydroxyquinoline, 8-hydroxyquinaldine, β-aminoethyl mercaptan, bisacetylacetone ethylenediimine, eriochrome black T, oxy , Quinaldic acid salicylaldoxime, picolinic acid, glycine, dimethylglyoxime oxy Mato,
Dimethylglyoxime, α-benzoinoxime,

N, N'-bis (1-methyl-3-oxobutylidene) ethylenediamine, 3-{(2-aminoethyl) amino} -1-propanol, 3- (aminoethylimino) -2-butaneoxime, alanine , N, N '
-Bis (2-aminobenzylidene) ethylenediamine,
α-amino-α-methylmalonic acid, 2-{(3-aminopropyl) amino} ethanol, aspartic acid, 1-
Phenyl-1,3,5-hexanetrione, 5,5′-
(1,2-ethanediyldinitrilo) bis (1-phenyl-1,3-hexanedione), 1,3-bis {bis [2- (1-ethylbenzimidazolyl) methyl] amino} -2-propanol, 1,2-bis (pyridine-α
-Aldimino) ethane, 1,3-bis {bis (2-pyridylethyl) aminomethyl} benzene, 1,3-bis {bis (2-pyridylethyl) aminomethyl} phenol, 2,2′-bipiperidine,

2,6-bis {bis (2-pyridylmethyl) aminomethyl} -4-methylphenol, 2,2 ′
-Bipyridine, 2,2'-bipyrazine, hydrotris (1-pyrazolyl) borate ion, catechol, 1,2
-Cyclohexanediamine, 1,4,8,11-tetraazacyclododecane, 3,4: 9,10-dibenzo-
1,5,8,12-tetraazacyclotetradecane-
1,11-diene, 2,6-diacetylpyridine dioxime, dibenzyl sulfide, N- {2- (diethylamino) ethyl} -3-amino-1-propanol, o-
Phenylenebis (dimethylphosphine), 2- {2-
(Dimethylamino) ethylthiodiethanol, 4,4 '
-Dimethyl-2,2'-bipyridine, N, N'-dimethyl-1,2-cyclohexanediamine, dimethylglyoxime, 1,2-bis (dimethylphosphino) ethane,
1,3-bis (diacetylmonooximino) propane,

3,3'-trimethylene dinitrobis (2
-Butane oxime) 1,5-diamino-3-pentanol dipivaloylmethane, 1,2-bis (diphenylphosphino) ethane, diethyldithiocarbamate ion,
N, N'-bis {2- (N, N'-diethylaminoethyl) aminoethyl} oxamide, ethylenediaminetetraacetic acid, 7-hydroxy-4-methyl-5-azahept-4-en-2-one, 2-amino Ethanol, N,
N'-ethylenebis (3-carboxysalicylideneamine), 1,3-bis (3-formyl-5-methylsalicylideneamino) propane, 3-glycylamino-1-propanol, glycylglycine, N'- (2-hydroxyethyl) ethylenediaminetriacetic acid, hexafluoroacetylacetone, histidine, 5,26: 13,18
-Diimino-7,11: 20,24-dinitrodibenzo [c, n] -1,6,12,17-tetraazacyclodocosin, 2,6-bis {N- (2-hydroxyphenyl) iminomethyl}- 4-methylphenol, 5,5
7,12,12,14-hexamethyl-1,4,8,1
1-tetraazacyclotetradecane-N, N ″ -diacetate,

1,2-dimethylimidazole, 3,3 '
-Ethylenebis (iminomethylidene) -di-2,4-pentanedione, N, N'-bis (5-amino-3-hydroxypentyl) malonamide, methionine, 2-hydroxy-6-methylpyridine, methyliminodiacetic acid,
1,1-dicyanoethylene-2,2-dithiol, 1,
8-naphthyridine, 3- (2-hydroxyethylimino) -2-butanone oxime, 2,3,7,8,12,
13,17,18-octaethylporphyrin, 2,
3,7,8,12,13,17,18-octamethylporphyrin, oxalic acid, oxamide, 2-pyridylaldoxime, 3- {2- (2-pyridyl) ethylamino}
-1-propanol, 3- (2-pyridylethylimino) -2-butanone oxime, 2-picolylamine, 3
-(2-pyridylmethylimino) -2-butanone oxime, dihydrogen diphosphite, 3-n-propylimino-2-butanone oxime, proline, 2,4-pentanediamine, pyridine,

N, N'-dipyridoxylideneethylenediamine, N-pyridoxylideneglycine, pyridine-2
-Thiol, 1,5-bis (salicylideneamino) -3
-Pentanol, salicylaldehyde, N-salicylidenemethylamine, salicylic acid, N- (salicylidene)-
N '-(1-methyl-3-oxobutylidene) ethylenediamine, salicylideneamine, N, N'-disalicylidene-2,2'-biphenylylenediamine, N, N'-
Disalicylidene-2-methyl-2- (2-benzylthioethyl) ethylenediamine, N, N'-disalicylidene-4-aza-1,7-heptanediamine, N, N'-disalicylideneethylenediamine, N-salicylide Denglycine, salicylaldoxime, N, N'-disalicylidene-o-phenylenediamine, N, N'-disalicylidene trimethylenediamine,

3-Salicylideneamino-1-propanol, tetrabenzo [b, f, j, n] -1,5,9,1
3-tetraazacyclohexadecine, 1,4,7-triazacyclononane, 5,14-dihydrodibenzo [b,
i] -1,4,8,11-Tetraazacyclotetradecine, tris (2-benzimidazolylmethyl) amine,
6,7,8,9,16,17,18,19-octahydrodicyclohepta [b, j] -1,4,8,11-tetraazacyclotetradecene, 4,6,6-trimethyl-
3,7-diazanone-3-ene-1,9-diol, tris (3,5-dimethyl-1-pyrazolylmethyl) amine, 2,2 ′: 6 ′, 2 ″ -terpyridine, 5,7,
7,12,14,14-hexamethyl-1,4,8,1
1-tetraazacyclotetradecane, tetrahydrofuran, tris (2-pyridylmethyl) amine, N, N,
N ′, N′-tetramethylurea,

N, N'-bis (3-aminopropyl) oxamide, N, N, N ', N'-tetrakis (2-pyridylmethyl) ethylenediamine, all-cis-5,
10,15,20-tetrakis {2- (2,2′-dimethylpropionamido) phenyl} porphyrin, 5,
10,15,20-tetraphenylporphyrin, 1,
4,7-tris (2-pyridylmethyl) -1,4,7-
Triazacyclononane, hydrotris (1-pyrazolyl) borate, 3,3′4-trimethyldipyrromethene,
Trimethylenediaminetetraacetic acid, 3,3'5,5'-
Tetramethyldipyrromethene, 5,10,15,20-tetrakis (p-triporphyrin) and the like.

In the method for producing a substrate in the present invention, a method in which a metal compound as a raw material of a metal oxide is converted into a gas and / or fine particles and reacted with oxygen, water, ammonia or the like is preferably used. When forming a base material, it is more preferable to form a base material using a specific substrate. The base material is formed by a method of reacting gas and / or fine particles of a metal compound with a metal oxide on the surface of the base material, or a method of depositing and / or laminating the gas and / or fine particle metal oxide. However, any method may be used. In addition, both of these methods can be used in combination.

As used herein, the term “specific substrate” refers to, for example, a metal oxide single crystal plate such as aluminum oxide, ordinary ceramic, metal containing silicon, glass, plastic, or the like. When using glass or plastic,
It is preferable that the surface is subjected to an orientation treatment. Of these, metal oxides are preferably used. Particularly preferably used are aluminum oxide, SrTiO ₃
And the like. The crystals in this case may be one or more single crystals, polycrystals, one or more semi-crystalline materials having both an amorphous part and a crystalline part, or a mixture thereof. You may. Most preferably, it is a single crystal. In this case, it is preferable that the substrate surface is a specific surface of the single crystal. Specifically, when aluminum oxide is used, the (0001) plane, SrTi
When O ₃ is used, the (001) plane is preferable. In addition, when a substrate made of a metal oxide is used as a structure, the substrate may or may not be included in the structure.

First, the metallized substance is converted into gas and / or fine particles. In order to obtain a metal oxide having protrusions, it is important to control the temperature conditions at this time. The temperature at this time depends on the metal compound used. The temperature is preferably a temperature at which the metal compound is vaporized, or a temperature at which it is heated to a higher temperature, and particularly preferably 50 to 200 ° C. The base material may be formed as it is by using the gas and / or the metal compound which has become fine particles, or the base material may be formed by spraying with another gas.

The gas used for spraying the gas and / or the fine metal compound is not particularly limited as long as it does not react with the metal compound used.
Specific examples include an inert gas such as nitrogen gas, helium, neon, and argon; carbon dioxide gas; organic fluorine gas; and organic substances such as heptane and hexane. Among these, an inert gas is preferable from the viewpoint of safety and economy. In particular, nitrogen gas is the most preferable in terms of economy.

When a substrate is formed on a substrate by spraying a gas and / or a metal compound which has been converted into fine particles with a gas, the distance between the outlet of the metal compound and the surface of the substrate is determined by the size of the substrate. Although it depends on whether or not the material is formed, this distance is preferably defined by the ratio of the distance between the outlet and the substrate surface / the length of the long axis of the opening. This value is preferably 0.01-1 and more preferably 0.05-0.
7, particularly preferably 0.1 to 0.5. Although this ratio varies depending on the shape of the outlet, a ratio of 1 or more is not preferable because the metal compound is not effectively converted to a metal oxide and the efficiency is poor.

The temperature of the substrate itself when the substrate is formed is:
The temperature is not particularly limited as long as the solid metal oxide is formed near and on the surface of the base material, but is preferably 0 to 800 ° C.
More preferably 20 to 700 ° C, particularly preferably 10 to 700 ° C.
0-600 ° C. When the substrate is a metal oxide, the substrate is more preferably grown epitaxially on the substrate. Whether the substrate is epitaxially grown on the substrate can be confirmed by a usual X-ray diffraction method. In particular, a method of confirming by observing the in-plane orientation relationship between the substrate and the substrate by the φ scan method is preferably used.

When the projection on the substrate is a metal oxide crystal, it is preferable that the crystal axes are in the same direction (the crystal axis directions are aligned). For example, it is preferable that the fluctuation of the crystal axis direction measured by the X-ray rocking curve method be within 5 degrees. If oxygen, water, ammonia, etc. are present in the system, metal oxides form in the apparatus before release, clogging and the like occur, and it is not possible to obtain a substrate having a desired form, which is not preferable. . However, if the metal compound is oxygen,
When the reaction rate with water, ammonia or the like is extremely low, oxygen, water, ammonia or the like may be coexisted in the system in advance.

The atmosphere in which the gas and / or fine metal compound and the substrate are present may be under reduced pressure, normal pressure or under pressure. However, when the process is performed under a high degree of reduced pressure, for example, under an ultra-vacuum, the growth rate of the metal oxide is low, and the productivity is poor.
When the treatment is performed under pressure, there is no problem with the oxide growth rate, but equipment for pressurization is required. Usually 0.001
It is preferably performed at 20 to atm, more preferably 0.1 to 10 atm. Most preferably, it is normal pressure.

FIG. 1 is a schematic view of an example of a reaction apparatus preferably used in the present invention. N ₂ is dehydrated by a liquid nitrogen trap. The metal compound is heated by a heater in a metal compound heating tank to become gas and / or fine particles, and is sprayed on the substrate through a nozzle and a slit by N ₂ . The line after the heating tank is heated by the ribbon heater. Al with the (0001) plane facing the slit on the substrate
_{A 2} O ₃ single crystal plate is used. On the substrate heated by the heater, the metal compound forms the substrate described in the present invention.
When forming the base material, a metal compound may be mixed into gas and / or fine particles, or a gas and / or fine metal compound may be mixed. Also,
Both of these methods can be used in combination.

The atmosphere in which the gas and / or the metal compound in the form of fine particles and the base material are present may be under reduced pressure, under normal pressure or under pressure. However, when the process is performed under a high degree of reduced pressure, for example, under an ultra-vacuum, the growth rate of the metal oxide is low, and the productivity is poor.
When the treatment is performed under pressure, there is no problem with the oxide growth rate, but equipment for pressurization is required. Usually 0.001
It is preferably performed at 20 to atm, more preferably 0.1 to 10 atm. Most preferably, it is normal pressure.

FIG. 1 shows a schematic diagram of an example of a reaction apparatus preferably used in the present invention. The conductive substance in the present invention refers to a substance having a specific resistivity of 10 Ω / m or less. Preferably, it is 1 Ω / m or less. Specifically, metal and / or metal paste, ITO (In ₂ O ₃ / Sn)
O ₂ ), conductive resin, carbon thin film, diamond thin film and the like. The type of metal is not particularly limited, but specific examples include copper, nickel, chromium, iron, gold, silver, palladium,
Examples include aluminum, zinc, tin, silicon, titanium and alloys thereof.

The substrate in the present invention is coated with a conductive substance. The conductive material may be divided into two or more parts. The expression “divided into two or more parts” means that the part is divided into two or more parts that do not substantially exhibit conductivity. This portion may be two or more, but it is preferable that the portion is electrically connected to one portion that is substantially electrically conductive to each other via another conductive material. In addition, when considering the use as a cold cathode element, the conductive substance needs to be covered including the protrusions in the base material.

Next, a method for forming or bonding a conductive substance to a substrate will be described. As this method, a method of directly forming a conductive material on a base material and a method of directly bonding the conductive material to the base material are known. As a method of forming a conductive material directly on a substrate, a method in which a conductive material is physically or chemically formed on a substrate through a gas phase or a liquid phase, and is formed by vapor deposition, sputtering, dipping, and solution plating. Plating, coating and printing.

The method of directly bonding the substrate and the conductive substance is as follows.
In addition to the conventionally known methods such as baking, Japanese Patent Publication No. 57-13
No. 515, the method described in JP-A-61-17475 and the like, that is, a powder of the conductive substance or a powder as a main component of the conductive substance is interposed between the conductive substance and the base material, A method of heating at a temperature lower than the melting point of the conductive substance in a reactive or inert atmosphere and performing a heat treatment may be used.

In the substrate of the present invention, the tips of the protrusions are coated with at least one substance selected from metals, metal oxides, and carbon thin films. Here, the tip means a portion including the apex of the protrusion. The distance from the apex of the projection is not particularly limited, and may cover the entire projection. However, this distance is preferably の of the length of the projection or 50 of the size of the cross section. Less than the greater of any of the two times, more preferably one of the length of the protrusion
/ 5 or 20 times the cross-sectional size, whichever is greater, and is more preferably １ ／ of the length of the projection.
It is equal to or less than the larger of 0 or three times the cross-sectional size.

In the structure according to the present invention, the tip of the protrusion is one.
Coated with more than one kind of electron emitting material. In the present invention, the term “electron-emitting substance” refers to a substance other than hydrogen in the periodic table.
Group 2, group 13, group 13 except boron, group 14 except carbon, group 15 except nitrogen, phosphorus and arsenic, Po and 3, 4, 5,
Elements belonging to groups 6, 7, 8, 9, 10, 11, 12;
It is a substance selected from the metal oxides and carbon thin films of the present invention.

In the Periodic Table, Group 1 and Group 2, excluding hydrogen,
Group 13 except boron, Group 14 except carbon, Group 15 except nitrogen, phosphorus and arsenic, Po and 3, 4, 5, 6, 7, 8,
Each of the elements belonging to Groups 9, 10, 11, and 12 specifically includes Li, Na, K, Rb, Cs, Be, Mg, Ca,
Sr, Ba, Al, Ga, In, Tl, Si, Ge, S
n, Pb, Sb, Bi, Po, Sc, Y, La, Ce,
Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu, Ti, Zr, Hf, V,
Nb, Ta, Cr, Mo, W, Mn, Tc, Re, F
e, Ru, Os, Co, Rh, Ir, Ni, Pd, P
t, Cu, Ag, Au, Zn, Cd, Hg, and alloys composed of two or more of these metal species, preferably Li, K, Cs, Mg, Sr, Ba, Al, T
i, Zr, Hf, Nb, Ta, Mo, W, Re, Fe,
Os, Co, Ir, Ni, Pt, Cu, Ag, Au, and alloys composed of two or more of these metals, more preferably Ni, Fe, and stainless steel.

In the present invention, the metal oxide as the electron-emitting material is a metal whose group in the periodic table is Group 1 except for hydrogen, Group 2 except for boron, Group 13 except for boron, Group 14 except for carbon,
Group 15, excluding nitrogen, phosphorus and arsenic, Po and 3, 4, 5,
It is an oxide that is an element belonging to Groups 6, 7, 8, 9, 10, 11, and 12. As the metal species, for example, Li, N
a, K, Rb, Cs, Be, Mg, Ca, Sr, Ba,
Al, Ga, In, Tl, Si, Ge, Sn, Pb, S
b, Bi, Po, Sc, Y, La, Ce, Pr, Nd,
Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, T
m, Yb, Lu, Ti, Zr, Hf, V, Nb, Ta,
Cr, Mo, W, Mn, Tc, Re, Fe, Ru, O
s, Co, Rh, Ir, Ni, Pd, Pt, Cu, A
g, Au, Zn, Cd, Hg, etc., among which Be, Na, Mg, Al, Si, K, Ca, Ti, C
r, Mn, Fe, Co, Ni, Zn, Ga, Ge, A
s, Y, Zr, Cd, In, Sn, Sb, Cs, Ba,
Pb, Bi, Th and the like are more preferable, and Mg, T
i, Ba, Sr, K, Ta, Nb, Li, Pb, Zr,
In and Sn are particularly preferred. These metals can be used alone or in combination of two or more. For example, barium titanate, SrTiO ₃ , PZ
T and the like. Further, an alkali metal and another metal can be used in combination. For example, Ta, Nb
KTaO ₃ or NbL
A metal oxide can be formed by forming a composite oxide such as iO ₃ . Most preferably, it is MgO.

The carbon thin film in the present invention is a thin film comprising carbon as an element constituting the thin film. Specific examples include graphite, graphite, diamond-like carbon, diamond and the like. Preferred are graphite, diamond-like carbon and diamond, and particularly preferred are diamond-like carbon and diamond. When the metal oxide is coated on the tip of the protrusion on the substrate, the metal oxide species of the substrate and the metal oxide species coated on the tip may be the same or different. Preferably different types.

The tip of the protrusion on the substrate is formed of metal, metal oxide,
As a method of coating with one or more kinds of substances selected from carbon thin films, any conventionally known method may be used. In this method, one or more substances selected from metals, metal oxides, and carbon thin films are physically or chemically coated on a substrate through a gas phase or a liquid phase, and are deposited, sputtered, and dipped. , And plating such as solution plating, coating,
Printing. Preferably, thermal decomposition chemical vapor deposition (hereinafter, chemical vapor deposition is abbreviated as CVD), hot filament CVD, plasma CVD, ion beam physical vapor deposition (hereinafter, physical vapor deposition) Is abbreviated as PVD method), ionized vapor deposition PVD method, ion implantation PVD method and the like. More preferably, a thermal decomposition CVD method,
A hot filament CVD method and a plasma CVD method. Further, considering the use as a cold cathode device, it is necessary that at least one kind of material selected from a conductive material, a metal oxide, and a carbon thin film be electrically connected to each other. FIG. 2 shows a schematic view of an example of a preferable structure.

The metal oxide structure of the present invention can be used with an external electrode attached. The external electrode may have any shape as long as it is electrically connected to the conductive material. Form conductive material and external electrode,
Alternatively, as a method of bonding, a method of bonding with solder, a method of wire bonding, or the like is used in addition to the method described in the case of the conductive substance and the metal oxide.

[0043]

The structure according to the present invention was able to increase the electron emission current value with a small electric field. Further, the structure of the present invention can be preferably used particularly for use as a cold cathode device.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of a reaction apparatus preferably used in the present invention.

FIG. 2 is a schematic view of a structure of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Keiichi Nakazawa, Inventor 1-3-1, Yoko, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Asahi Kasei Kogyo Co., Ltd. (72) Hideo Kinoshita 1-3-3, Yakko, Kawasaki-ku, Kawasaki-shi, Kanagawa No.1 Asahi Kasei Kogyo Co., Ltd. F-term (reference) 4F100 AA17A AA18C AA19 AA37 AB02C AB04C AB16C AR00B AS00C AT00A BA02 BA03 BA07 BA10A BA10C DC30C DD03A GB41 JA11A JG01B JG10 YY00A 5C027 AA03 AA03 AA03

Claims (9)

[Claims] 1. A part of or the entire surface of a substrate made of a metal oxide and having a projection is covered with a conductive material, and the tip of the projection is covered with at least one kind of electron-emitting material. Structure. 2. The protrusion is 10 μm × 10 μm on a substrate.
The structure according to claim 1, wherein the structure is present at a density of 0.01 to 10000 per area. 3. The protrusion has a cross-sectional circle-converted diameter of 0.01 to 0.01.
10,000 μm, and the ratio of the length / cross-section equivalent circle diameter is 1
The structure according to claim 1, wherein the structure is a rod. 4. The structure according to claim 1, wherein the central axes of the projections are parallel to each other. 5. The structure according to claim 1, wherein the substrate is a metal oxide single crystal. 6. The method according to claim 1, wherein the metal oxide crystals forming the protrusions are grown on the substrate in parallel with each other and in the same crystal axis direction. The described structure. 7. The material according to claim 1, wherein the electron emitting material covering the tip of the projection is at least one material selected from nickel, iron, stainless steel, MgO, and a carbon thin film. Structure. 8. The method according to claim 1, wherein an external electrode is provided on the conductive material.
The structure according to any one of to 7. 9. A cold cathode device comprising the structure according to claim 1.