JP4767280B2 - ZnO-based field emission electron source - Google Patents

Description

  The present invention relates to a field emission electron source made of ZnO containing Ga having a protruding shape and a method for manufacturing the same. The field emission electron source of the present invention can be effectively used as an electron emission source of a light source such as an image / video display device or illumination.

Conventionally, a hot cathode source such as a cathode ray tube has been used as the electron emission source. Since the hot cathode source emits electrons by thermal energy, it is necessary to increase the temperature by the heat source, and it is difficult to reduce the size of the light emitting device or the like. Also, the energy efficiency of the hot cathode source is low. Therefore, in recent years, the expectation of a field emission electron source that does not require thermal energy for electron emission is increasing.
As the field emission electron source, there is one using a silicon semiconductor microfabrication technique called Spindt type. This method is an application of silicon processing technology with advanced miniaturization. However, this method is a complicated manufacturing that requires a large number of steps using a large-scale silicon process facility.
In view of the present situation, the present inventors have obtained a metal oxide structure having a protrusion shape by using the method disclosed in Patent Document 1, that is, an organometallic decomposition method (hereinafter referred to as “atmospheric pressure MOCVD method”). Proposed. Furthermore, an electron-emitting device as shown in Patent Document 2 was proposed using the metal oxide structure having the protrusions. Patent Document 3 proposes an electron-emitting material in which a compound such as a metal, carbon nitride, or metal oxide is laminated on a protrusion made of a metal oxide, and an electron-emitting device with improved energy efficiency is proposed. .

  In general, as a characteristic of a field emission source, it is desired from the viewpoint of energy saving to obtain a high current density with a low electrolytic strength. As a method for improving the characteristics of such an electron emission source, in Patent Document 3, a carbon nitride film is laminated on the surface of a ZnO whisker containing a small amount of Al. However, such a method requires complicated steps and the field emission source characteristics are not sufficient. In addition, metal oxides such as In, Sn, and Ti, which have been confirmed to have an electrolytic emission effect, are widely used for transparent electrodes and others, and their reserves are limited. There is a problem with ease. Since ZnO, which has been confirmed to have an effect of electrolytic emission, is a readily available and inexpensive metal oxide, a metal oxide protrusion made of ZnO that is inexpensive and easily available is used as an electron emission source. Therefore, it is desired to provide a high-performance field emission source capable of obtaining a high current density with a low electrolytic strength. When this field emission source is used in a light emitting device, electrons emitted from the cathode electron emission source strike the phosphor and emit light. At this time, cations are generated from the phosphor and the atmospheric gas, and the cations are generated. If the electron emission source collides with the cathode and repeatedly emits electrons, there is a problem that the performance of the electron emission source deteriorates. It is desired.

International Publication No. 99/57345 JP 2000-276999 A JP 2002-274819 A

  That is, the present invention relates to provision of a high-performance field emission source capable of obtaining a high current density with low electrolytic strength, and a light emitting device using the same.

  The field emission source of the present invention is a field emission electron source comprising a ZnO protrusion-shaped article, wherein the ZnO protrusion-shaped article contains Ga in a mol% ratio of 0.02 mol% to 0.4 mol%. is there. Since Ga is a group 13 element, it functions as an n-type dopant for the ZnO semiconductor crystal and has the function of improving the electrical conductivity of the ZnO protrusion-shaped material. Therefore, it is considered that the inclusion of a small amount of Ga in the ZnO protrusion-shaped article makes it easier for electrons to move through the ZnO protrusion, and electron emission is likely to occur even with a small electric field strength.

The electron emission electron source made of a ZnO protrusion-shaped article containing Ga of the present invention can be produced using Ga (C ₅ H ₇ O ₂ ) ₃ which is a β-diketone complex of gallium as the Ga source. Since Ga (C ₅ H ₇ O ₂ ) ₃ becomes a gas near 100 ° C. and exists in a carrier gas such as air or nitrogen at an appropriate concentration, for example, Zn (C ₅ H ₇ O ₂ ) ₂ is vaporized. When forming a ZnO protrusion-shaped object on a substrate, Ga (C ₅ H ₇ O ₂ ) ₃ can be mixed in a carrier gas to produce a field emission electron source containing Ga in the ZnO protrusion-shaped object.
By annealing the ZnO protrusion-shaped object containing a small amount of Ga of the present invention in a hydrogen atmosphere, a field emission electron source with further excellent field emission characteristics can be obtained. It is estimated that annealing in a hydrogen atmosphere generally improves the crystallinity of ZnO crystals, improves the electron mobility as an n-type semiconductor, and has excellent field emission characteristics.
The field emission electron source of the present invention can be used as a light emitting device by applying emitted electrons to a phosphor.

That is, the present invention is as follows.
[1] A projection-shaped field emission electron source containing ZnO and Ga oxide, wherein Ga constituting the Ga oxide is 0.02 mol% in a Ga mol% ratio with respect to Zn constituting the ZnO. 0.4 mol%, and the protrusion shape has a protrusion shape substantially vertically on the substrate, and the substantially vertical length of the protrusion shape on the substrate is 10 μm to 100 μm. Protrusion-shaped field emission electron source.
[2] The above-mentioned [1], wherein the ZnO is formed by a CVD method using a β-diketone complex of Zn as a raw material, and the Ga oxide is formed of a β-diketone complex of Ga as a raw material. Projection-shaped field emission electron source.
[3] A light-emitting device using the projection-shaped field emission electron source according to [1] or [2].

  The field emission electron source of the present invention is easy to manufacture, inexpensive and easily available. Further, this field emission electron source is a field emission electron source having a long lifetime in which a necessary current density can be obtained with a low electric field intensity and the field emission characteristics do not change even when used repeatedly. By using this field emission source for a light-emitting device, a light-emitting device that can be easily manufactured with an inexpensive raw material and has a long lifetime can be provided.

Hereinafter, embodiments of the present invention will be described in detail.
The ZnO protrusion-shaped object referred to in the present invention is a protrusion shape mainly composed of ZnO having a length of more than 10 μm. For example, as shown in the electron micrograph of FIG. I have it. The length range of the ZnO protrusion-shaped product is not particularly limited, but is usually 10 μm to 100 μm, preferably 10 μm to 50 μm, and more preferably 15 μm to 30 μm. The length of the ZnO protrusion-shaped object is determined by making the electron-emitting device and the electric wiring shown in FIG. 2 using different lengths of the ZnO protrusion-shaped object and examining the field method emission power supply characteristics. be able to.

For the field emission power supply characteristics, the electrically wired element shown in FIG. 2 is placed in a vacuum, and the current density and electric field strength in the vacuum are obtained. The good element electric field method emission power characteristics, can be determined by obtaining the current density in the range of current density 0.1 .mu.A / cm ² of 100 .mu.A / cm ² at a lower electric field intensity. Length and in excess of 100μm of ZnO projection shape was shorter than 10μm may or not reach the current density 100 .mu.A / cm ^2, the electric field strength at a current density of 100 .mu.A / cm ² is reached the the 20V / [mu] m It is not appropriate. The field emission power supply characteristics of the ZnO protrusions are such that electrons are emitted from a pointed tip, so that a certain length and a minimum tip sharpness are important, and those with a length shorter than 10 μm are long. If the length is less than 100 μm, it is easy to make a thick one, and it is considered that the problem is that the tip sharpness is extremely small.

The number of ZnO projection shape of the present invention, the projection shape composed mainly of ZnO in excess of length 10μm is preferably 100000 present from 100 per area of 1 mm ^2, more preferably 50,000 present from 1000, 2000 More preferably, the number is 10,000. Regarding this number, the performance was judged by making the electron-emitting device and the electric wiring shown in FIG. 2 using the ZnO protrusions having different numbers in the same manner and examining the field emission power supply characteristics. If the number of ZnO protrusion-shaped objects per 1 mm ² area is less than 100, there are too few places to emit electrons, and good field emission power supply characteristics cannot be obtained. On the other hand, if the number of ZnO protrusion-shaped objects per 1 mm ² area exceeds 100,000, it is considered that there are too many electron emission places, the electric field is not concentrated, and the characteristics are not good.

The substrate of the ZnO protrusion-shaped product of the present invention is not particularly limited as long as it is an electrically conductive substrate. The degree of electrical conductivity is not particularly limited, but it is preferable to obtain a current density of 1 mA / cm ² or more, and a semiconductor substrate such as silicon, GaAs, SiC, or metal oxide, or a metal substrate can be used.
The ZnO protrusion-shaped article of the present invention contains Ga in the ZnO protrusion-shaped object in a ratio of Ga mol% to Zn of 0.02 mol% to 0.4 mol%. The mol% ratio referred to in the present invention is a solution obtained by dissolving a ZnO protrusion shaped product containing Ga in 100 ml of 1N hydrochloric acid solution, and measuring the Ga concentration and the Zn concentration in the solution A by ICP emission spectrometry. It is a mole% ratio calculated and converted to the number of moles. That is, the Ga mol% ratio to Zn is expressed by the following formula.
Ga mole% ratio to Zn = (number of moles of Ga in solution A / number of moles of Zn in solution A) × 100

The ZnO protrusion-shaped article of the present invention can be produced by the atmospheric pressure MOCVD method apparatus shown in FIG. In order to form a ZnO protrusion-shaped article by atmospheric pressure CVD, a material capable of vaporizing a zinc component by applying an appropriate temperature as the raw material can be used as the raw material. As this Zn raw material, a zinc complex in which zinc and a ligand are coordinated like a β-diketone complex such as zinc and acetylacetone, zinc and alkoxide group, alkyl group, phenyl group, alkylphenyl group, olefin group In addition, an organic zinc compound and a zinc halogen compound in which a conjugated diene group such as an aryl group or a cyclobutadiene group is bonded can be used. When a zinc raw material is an organic zinc compound such as bisacetylacetonatozinc, diethylzinc or dimethylzinc, which is an acetylacetone complex of zinc, high-quality ZnO in which no impurities are mixed into the ZnO protrusion shape is formed, which is more preferable. When using Zn (C ₅ H ₇ O ₂ ) ₂ , which is a β-diketone compound of Zn, that is, bisacetylacetonato zinc as a raw material, this raw material is set to an appropriate temperature in the range of 80 ° C. to 150 ° C., By introducing a carrier gas such as nitrogen or argon onto the substrate, a ZnO protruding shape can be produced.

  The ZnO protrusion shape containing Ga of the present invention can be produced by vaporizing the Ga raw material before or after the carrier gas vaporizing the Zn raw material. Therefore, the raw material of Ga is not particularly limited as long as it contains gallium and can vaporize gallium, but gallium and a ligand are coordinated like gallium and a β-diketone complex such as acetylacetone. Gallium complexes, gallium and alkoxide groups, alkyl groups, phenyl groups, alkylphenyl groups, olefin groups, aryl groups, organic gallium compounds and gallium halogen compounds in which conjugated diene groups such as cyclobutadiene groups are bonded Can do.

When an organic gallium compound such as trisacetylacetonatogallium, triethylgallium, or trimethylgallium, which is a gallium acetylacetone complex, is used as a gallium raw material, a ZnO protrusion-shaped product containing Ga with less impurities is more preferable. The Ga mol% ratio can be adjusted by changing the raw material temperature because the concentration of the gallium raw material in the carrier gas differs when the temperature of the gallium raw material is changed. In order to produce a ZnO projection-shaped product containing Ga of the present invention in a Ga mol% ratio of 0.02 mol% to 0.4 mol% with respect to Zn, Ga (C ₅ H ₇ O ₂ ) _3, that is, tris When acetylacetonatogallium is used, the raw material vaporization temperature is preferably adjusted to a range of 80 ° C to 120 ° C.

In order to produce a ZnO protruding shape containing Ga on the substrate in the present invention, ZnO, Ga source and oxygen must be reacted on the substrate to form ZnO and Ga oxide. Therefore, an oxygen component is necessary on the substrate. Examples of the oxygen component source include air, oxygen, water, ozone and the like, but it is easy to use air and is preferable. Further, the substrate temperature needs to be 300 ° C. to 1000 ° C. in order to form ZnO, and the substrate temperature is preferably 500 ° C. to 800 ° C., and the substrate temperature is 600 ° C. to 700 ° C. More preferred.
It is desirable that the ZnO protrusion-shaped material containing Ga of the present invention is annealed in a hydrogen atmosphere. By placing a ZnO protrusion-shaped object containing Ga on the substrate in a hydrogen flow and annealing at a temperature of 300 ° C. to 500 ° C. for 30 minutes to 4 hours, the field emission power supply characteristics are improved. The hydrogen concentration at the time of annealing may be 100% hydrogen, but an additional active gas such as nitrogen or argon may be mixed into hydrogen.

  Since the ZnO protrusion-shaped article containing Ga of the present invention emits electrons with a low electric field strength and does not deteriorate in performance even when the electrons are repeatedly emitted, the light emitting device can be obtained by applying the emitted electrons to the phosphor. Can be used as In addition, X-rays are generated by emitting electrons from the ZnO protrusion-shaped object containing Ga according to the present invention, and accelerating the electrons to hit a metal such as copper or tungsten. Can also be used as a source. A feature of the light-emitting device or X-ray apparatus using the electron emission source of the present invention is that the electron emission source emits electrons by a surface, and therefore can emit light or emit X-rays on a wide surface.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example etc., this invention is not limited at all by these Examples.
[Examples 1 to 5]
FIG. 3 is a schematic view of an apparatus for manufacturing the projection-shaped field emission electron source of the present invention. The manufacturing apparatus includes a supply source 51 for nitrogen as a carrier gas, a flow meter 57 for adjusting the flow rate of the carrier gas, a heating tank 53a for vaporizing a gallium compound as a raw material, and a heating tank 53b for vaporizing a zinc compound, A pipe 54 for introducing the carrier gas into the heating tanks 53a and 53b, pipes 55 and 59 for guiding the metal compound vaporized in the heating tanks 53a and 53b to the outlet 58, a substrate stage 56 for holding the substrate 11 in a heated state, Further, the air supply source 61 is a reaction medium, and a pipe 60 for introducing air with a controlled flow rate into the pipe 59.
The pipe 54 is provided with a water trap 52 made of liquid nitrogen. The heating tanks 53a and 53b are arranged in series. The flow meter 57 is provided with a needle valve 57a so that gas can be turned on and off and the gas flow rate can be adjusted. The water trap 52 made of liquid nitrogen is for removing water contained in the carrier gas supplied from the nitrogen supply source 51.

In this example, a compressed nitrogen cylinder (moisture pressure of 1.4 Pa or less, manufactured by Fuji Acetylene Co., Ltd.) was used as a nitrogen supply source. The air supply source 61 removes moisture in the air by pressurizing the air to 7.07 × 10 ⁵ Pa with a compressor (not shown) and cooling it to −40 ° C. with an air dryer (not shown). Yes. The moisture pressure in the air at this time was 3.4 Pa.
Before entering the outlet 58, the carrier gas and the raw material gas are mixed in the pipe 59. A blowout 58 is connected to the tip of the pipe 59, and an opening 58a of the blowout 58 is formed so that the gas from the pipe 59 is blown out over the entire surface of the substrate 11 on which the metal oxide 12 is formed. Has been. Further, the pipes 54, 55, 59 and the blowout port 58 (portions indicated by double lines and triple lines in FIG. 3) are heated by a ribbon heater. The blowout port 58 was a hollow cone having an inner diameter of 80 mmφ, a height of 46 mm, and a thickness of 10 mm. There is a joint portion with the pipe 59 at the apex portion of the cone, and an opening 58a is formed on the bottom surface (a portion forming a circle) of the cone. The openings 58a of the blowout ports 58 have 1 mmφ holes arranged in a staggered manner with a center distance of 2 mm. The range of the portion where the holes are arranged is 20 mm square by the distance between the centers of the outermost holes.

Ga (C ₅ H ₇ O ₂ ) ₃ was charged into the heating tank 53a, and the temperature of the heating tank was 90 ° C. in Example 1, 100 ° C. in Example 2, 110 ° C. in Example 3, 115 ° C. in Example 4, In Example 5, it heated at 120 degreeC, respectively. Zn (C ₅ H ₇ O ₂ ) ₂ was charged into the heating tank 53b and heated to 108 ° C. The outlet 58 was heated to 200 ° C.
The opening 58 a of the outlet 58 is arranged so that the center of the holed portion is the center of the lower substrate 11. As the substrate 11, an n-type Si (100) substrate (manufactured by SUMCO Corporation, specific resistivity ≦ 0.1 Ω · cm, 25 mm square) was used. Note that a quartz plate having a thickness of 0.5 mm having a square opening of 15 mm square was disposed on the substrate 11 as a mask. The position of the quartz plate is such that the center of the opening coincides with the center of the portion where the hole of the opening 58a of the outlet 58 is disposed, and the surface of the quartz plate and the hole of the opening 58a are disposed. They were placed so that the surfaces were parallel. The substrate 11 was heated to 650 ° C. by heating the substrate stage 56. At the center of the portion where the hole of the blowout port 58 is arranged, the temperature at the end of the opening 58a of the blowout port 58 and the center of the distance between the substrates 11 was 245 ° C.

Dry air was introduced into the heating tank 53a at a flow rate of 2.5 dm ³ / min. At the same time, dry air was introduced into the pipe 59 connected to the outlet 58 at a flow rate of 2.5 dm ³ / min. For 60 minutes from the start of spraying, a ZnO protrusion-shaped object containing Ga was grown almost perpendicularly to the Si substrate 11 to obtain a protrusion-shaped object containing ZnO as a main component. The ZnO protrusion-shaped object containing Ga grown on the Si substrate is annealed at 400 ° C. for 1 hour while flowing hydrogen along with the substrate to obtain a protrusion-shaped object whose main component is ZnO adhering vertically to the Si substrate. It was.
A projection as shown in FIG. 2 was formed on the protrusion-shaped product mainly composed of ZnO adhering perpendicularly to the obtained Si substrate, and the field emission characteristics and the light emission characteristics using the same were evaluated.
A lead electrode 4 made of stainless steel mesh was attached on the conductive film D2 via a partition member 6b made of insulating alumina. The distance between the conductive film D2 and the extraction electrode 4 is 250 μm, and the conductive film D2 and the extraction electrode 4 are electrically insulated. The stainless steel mesh constituting the extraction electrode 4 has 0.3 mm square holes formed at intervals of 0.5 mm. This 0.3 mm square hole becomes a hole 14 that exposes the tip of the protrusion.

Using the apparatus schematically shown in FIG. 2, phosphor H was formed on the transparent conductive film side of quartz substrate G1 provided with transparent conductive film D1 in the following procedure.
After forming the transparent conductive film D1 formed by the same method as the above-described transparent conductive film D2 on the quartz substrate G1, the side on which the transparent conductive film D2 is formed is placed toward the blowing port 58 and heated to 650 ° C. did. Y (C ₁₁ H ₁₉ O ₂ ) ₃ and Eu (C ₁₁ H ₁₉ O ₂ ) ₃ were charged at a weight ratio of 2: 1 to the heating tank 53b and heated to 220 ° C. C ₁₁ H ₁₉ O ₂ forming a metal compound of Y and Eu charged in the heating bath 53b is a dipivalomethanato group. The heating tank 53a, the piping 55, and the outlet 58 were heated to 230 ° C. with a ribbon heater.
A quartz substrate G1 (25 mm square) coated with the transparent conductive film D1 was disposed at the center of the portion where the hole of the opening 58a of the outlet 58 is disposed. The quartz substrate G1 coated with the transparent conductive film D1 was arranged with a quartz plate having a thickness of 0.5 mm having a square opening of 15 mm square as a mask, and the formation site of the phosphor H was determined. In the quartz plate, the center part of the opening part is made to coincide with the center part of the part where the hole of the opening part 58a of the outlet port 58 is arranged, and the surface of the quartz plate and the surface part of the opening part 58a of the outlet part 58 become parallel. Arranged. The quartz substrate G1 coated with the transparent conductive film D1 was heated to 700 ° C. by the substrate stage 56.

In this state, by introducing nitrogen from the nitrogen supply source 51 into the pipe 54 at a flow rate of 1.2 dm ³ / min, a mixed metal compound gas of Y and Eu using nitrogen gas as a carrier is passed through the pipe 55. Then, the phosphor H was formed by spraying the transparent conductive film D1 of the quartz substrate G1 from the outlet 58 for 50 minutes. Thereby, Y ₂ O ₃ : Eu is formed as the phosphor H. At this time, air was not introduced into the outlet 58.
What was produced in this way was put in the vacuum chamber, and the field emission characteristic and the light emission characteristic using it were evaluated. At this time, the transparent conductive film D1 was connected to the positive side of the variable DC power source B1 equipped with a voltmeter through the terminal of the vacuum chamber. Further, an ammeter A was connected to the conductive film D2 through a terminal of the vacuum chamber, and then connected to one pole side of the variable DC power sources B1 and B2 equipped with a voltmeter and to the ground. The current value indicated by the ammeter A is the cathode current value emitted from the electron-emitting device. In FIG. 2, the portion on the left side from the dotted line is located in the vacuum chamber, and the portion on the right side from the dotted line is located outside the vacuum chamber. The upper surface portion of the vacuum chamber is made of transparent glass, and the quartz substrate G1 and the like coated with the phosphor H and the transparent conductive film D1 can be observed from the upper surface portion of the vacuum chamber.

After closing the vacuum chamber, the inside of the vacuum chamber was evacuated from 7 × 10 ⁻⁶ Pa to 5 × 10 ⁻⁵ Pa. Furthermore, the DC variable power source B2 was set to 3000V. The DC variable power source B1 was boosted at a rate of 50 V / min until a stable cathode current value was obtained from 500V. Thereafter, in a stable cathode current density of 100 .mu.A / cm ² and 0.1 .mu.A / cm ^2, and the respective voltage values calculated field strength for the read current density. The electric field strength at a current density of 100 μA / cm ² was set as an electrolytic strength of 100, and the electric field strength at a current density of 0.1 μA / cm ² was set as an electrolytic strength of 0.1.
In order to investigate the light emission area ratio at a current density of 50 μA / cm ² , a portion where the phosphor H emits light was observed from the direction perpendicular to the phosphor H. This photograph is made to the actual size, and the light emitting part and the part that does not emit light are separated through a transparent plate in which a grid is drawn in 1 mm vertical and horizontal increments within a 15 mm × 15 mm square area of the same size as the phosphor H. Separately, the emission area ratio was determined, and the emission area ratio at a current density of 50 μA / cm ² is shown in Table 1.

To examine the reproducibility of the electric field intensity in addition repeated discharges, as subsequently current density 100 .mu.A / cm ² in 10 minutes emitted was 1 this by cycle After emission 10 minutes at a current density of 0.1 .mu.A / cm ^2, a cycle test went. The extracted electrolytic strength after one cycle shown in Table 1 is the electrolytic strength at a current density of 100 μA / cm ² measured after one cycle, and the electrolytic strength at a current density of 100 μA / cm ² measured after 100 cycles.
After the evaluation of the field emission characteristics and the light emission characteristics, the substrate 12 with the protrusion-shaped object mainly composed of ZnO was taken out from the vacuum chamber. The substrate 12 with the protrusion-shaped material mainly composed of ZnO was observed with an electron microscope to observe the length and existence density of the protrusion-shaped material. In this electron microscope observation, gold vapor deposition was very thinly observed on the surface. The length and density of the protrusion-shaped object were measured for objects having a length exceeding 10 μm.
After observing with an electron microscope, in order to measure Ga mol% of the protrusion-shaped product containing ZnO as the main component, the entire substrate 12 with the protrusion-shaped material containing ZnO as the main component was dissolved in 1N hydrochloric acid and analyzed by ICP emission spectrometry. The concentration of Ga and Zn was determined by the method, and Ga mol% in the protrusion-shaped product was determined and shown in Table 1.
In this example, a current density of 100 μA / cm ² can be obtained with a low electric field strength, and the low electric field strength does not change even in repeated field emission of 100 cycles, and the lifetime is long.

[Comparative Example 1]
The protrusion-shaped object 12 made of ZnO was formed in the same manner as in Example 1 except that the temperature of the heating tank 53a was adjusted to 100 ° C. without charging the raw material in the heating tank 53a, and the field emission characteristics were evaluated. . The results are shown in Table 2.
In this comparative example, the protrusion-shaped object is made of ZnO and does not contain Ga. In this case, a current density of 100 .mu.A / cm ² obtained in high field strength than in the Examples, moreover even after repeated field emission 100 cycles, the electric field strength is further increased, the life is short.

[Comparative Example 2]
In the same manner as in Example 1 except that Ga (C ₅ H ₇ O ₂ ) ₃ was charged in the heating tank 53a, the temperature of the heating tank 53a was adjusted to 125 ° C., and the growth time of the protrusion-shaped object was 120 minutes. A protrusion-shaped object 12 made of ZnO was formed, and field emission characteristics were evaluated. The results are shown in Table 3.
In this comparative example, since the growth time of the protrusion-shaped object was slow, it took more time than in the example to obtain a protrusion-shaped object having substantially the same length as the example.
In this comparative example, 1.03 mol% of Ga is included in the protrusion-shaped object. In this case, a current density of 100 .mu.A / cm ² obtained in high field strength than in the Examples, moreover even after repeated field emission 100 cycles, the electric field strength is further increased, the life is short.

[Comparative Examples 3 to 7]
Al (C ₅ H ₇ O ₂ ) ₃ is charged into the heating tank 53a, and the temperature of the heating tank is 90 ° C. in Comparative Example 3, 100 ° C. in Comparative Example 4, 110 ° C. in Comparative Example 5, 115 ° C. in Comparative Example 6, In Comparative Example 7, the protrusion-shaped object made of ZnO was prepared in the same manner as in Example 1 except that the protrusion-shaped object formation time was adjusted so that the average length of the protrusion-shaped object was 23 μm to 25 μm. 12 was formed, and field emission characteristics were evaluated. The results are shown in Table 4.
In this comparative example, 0.07 mol% to 0.95 mol% of Al is included in the protrusion-shaped object, and Ga is not included. In this case, a current density of 100 μA / cm ² can be obtained with substantially the same electric field intensity as in the example, but the electric field intensity is further increased and the life is short even after 100 cycles of repeated field emission.

  According to the present invention, a field emission type electron-emitting device with low power consumption and long repetition life can be obtained. This field emission element can be effectively used as a field emission element for a light source such as an image / video display device, illumination, or a micro vacuum tube.

The electron micrograph of the ZnO protrusion shape object grown on the silicon substrate. The schematic block diagram of the apparatus for measuring a field emission characteristic. The schematic block diagram of the apparatus for implementing atmospheric pressure MOCVD method.

Explanation of symbols

A Ammeter B1 DC variable power supply B2 DC variable power supply D1 Transparent conductive film D2 Conductive film H Phosphor G1 Quartz substrate G2 Base plate 4 Extraction electrode 6a Partition member 6b Partition member 11 Substrate 12 Metal oxide 14 having a protrusion-shaped object Hole 51 for exposing the front end portion 52 Nitrogen supply source 52 Water trap 53a by liquid nitrogen Heating bath 53b Heating bath 54 Piping 55 Piping 56 Substrate stage 57 Flow meter 57a Needle valve 58 Outlet 58a Opening 59 Piping 60 Piping 61 Air supply source

Claims (3)

A projection-shaped field-emission electron source containing ZnO and Ga oxide, wherein Ga constituting the Ga oxide is in a ratio of 0.02 mol% to 0.02 mol% with respect to Zn constituting the ZnO. A protrusion having a protrusion shape of 4 mol%, wherein the protrusion shape has a protrusion shape substantially perpendicular to the substrate, and the length of the protrusion shape on the substrate in the substantially vertical direction is 10 μm to 100 μm. Shaped field emission electron source.   2. The projection-shaped electric field according to claim 1, wherein the ZnO is formed by a CVD method using a Zn β-diketone complex as a raw material and the Ga oxide is formed using a Ga β-diketone complex as a raw material. Emission electron source.   A light emitting device using the projection-shaped field emission electron source according to claim 1.