JPH11232994A - Electron-emitting device - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a high-efficiency electron-emitting device applicable to a display or the like. The device includes an electron emission surface of a diamond film, two electrodes disposed so that electrons move along the diamond film surface, and another electrode for applying an electric field to extract electrons from the diamond surface. . Of the two electrodes placed so that electrons move along the surface of the diamond film, the back surface without the conductive layer and the other surface surface with the conductive layer And is electrically connected to the conductive layer. Two electrodes placed so that the electrons move along the surface of the diamond film are in contact with different parts of the diamond film, and there is a gap between the two electrodes and the part of the diamond film that is not in contact with either electrode. Exists.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission display which is expected to be a self-luminous planar display, and an electron-emitting device which can realize a high-efficiency emitter for a high-frequency, high-power, and noise-resistant microelectronic device. . In particular, the present invention relates to a structure of an electron-emitting device using highly efficient electron emission from a diamond surface.

[0002]

2. Description of the Related Art In recent years, micron-sized microelectron-emitting devices have attracted attention as an electron beam source replacing a high-definition thin display electron gun and as an emitter of a microvacuum device capable of high-speed operation. There are various types of such electron-emitting devices, and a field emission type (FE type), a tunnel injection type (MIM type, MIS type), a surface conduction type (SC type) and the like are known.

The FE type electron-emitting device emits electrons from a cone-shaped protrusion made of silicon (Si) or molybdenum (Mo) by applying a voltage to a gate electrode and applying an electric field to the electron-emitting portion. It is to let.

[0004] Further, the MIM-type and MIS-type elements form a laminated structure of a metal, an insulator layer, a semiconductor layer, and the like, so that a part of electrons injected from the metal side is extracted to the outside from an electron emitting portion. is there.

[0005] In the SC type, electrons are extracted from an electron emission portion formed in advance by flowing a current in an in-plane direction of a thin film formed on a substrate. Electrons are emitted from the fine cracks.

[0006] These element structures have features such as downsizing and integration by using fine processing technology.

[0007]

Generally, the characteristics required as a material for an electron-emitting device are (1) that electrons are easily emitted by a relatively small electric field, that is, the material has a small electron affinity, 2) In order to maintain stable electron emission characteristics, the emitter surface is chemically stable;
(3) It has excellent abrasion resistance and heat resistance.

In view of the prior art from such a point of view, the field emission type element has a large dependence of the emission current on the shape of the emitter portion, making it very difficult to manufacture and control the field emission element, and to reduce the surface of the material used. There were issues in terms of stability. Also in this scheme, each element is a point electron emission source,
It has been difficult to obtain a planar electron emission flow.

In the avalanche amplification type, since it is generally necessary to apply a very large amount of current to the element, heat is generated in the element, which causes unstable electron emission characteristics and shortens the life of the element. There was a problem. In the avalanche amplification type, the work function amount of the electron emission portion is reduced by providing a cesium layer or the like on the surface of the emitter, but a material having a small work function such as cesium has a chemically unstable surface state. There is also a problem that it is not stable, that is, the electron emission characteristics are not stable. As described above, the materials and structures used so far do not sufficiently satisfy the characteristics required for the electron-emitting device.

[0010] On the other hand, diamond is a semiconductor material having a wide bandgap (5.5 eV), and has characteristics such as high hardness, abrasion resistance, high thermal conductivity, and chemical inertness. Very suitable as a device material. In addition, by controlling the surface state of diamond,
It is possible that the energy level at the conduction band edge becomes higher than the energy level of the vacuum, that is, a state of negative electron affinity. That is, there is an advantage that if electrons are injected into the conduction band of the diamond layer, electrons can be easily emitted. In addition, diamond can generally be easily formed by a gas phase synthesis method using carbon-based gas species and hydrogen gas as source gases, and has an advantage in terms of manufacturing.

In order to solve the above-mentioned problems in the prior art, the present invention provides an electron emission surface of a diamond film, two electrodes provided so that electrons move along the diamond film surface, and an electron beam from the diamond surface. Another object of the present invention is to provide a high-efficiency electron-emitting device by including a constituent element composed of another electrode for applying an electric field for extracting electric field.

[0012]

Means for Solving the Problems In order to achieve the above object, the structure of the electron-emitting device according to the present invention comprises at least:
Including a component comprising an electron emission surface of a diamond film, two electrodes arranged to move electrons along the diamond film surface, and another electrode for applying an electric field for extracting electrons from the diamond surface. It is characterized by the following.

Another configuration according to the present invention is that, of the two electrodes provided so that the diamond thin film surface includes a conductive layer and electrons move along the diamond film thin film surface,
One is formed on the back side without the conductive layer and the other is formed on the front side with the conductive layer, and is electrically connected to the conductive layer.

In the above structure, the conductive layer on the surface of the diamond thin film is a hydrogenated diamond layer.

According to another configuration of the present invention, two electrodes provided so that electrons move along the surface of a diamond film are in contact with different portions of the diamond thin film, and a gap is provided between the two electrodes. And there is a portion of the diamond thin film that is not in contact with either electrode.

Further, another configuration according to the present invention is characterized in that the thickness of the diamond thin film is 10 nm or more and 5 μm or less.

In the above structure, a diamond thin film is grown by a vapor phase growth method, and 1x is used as a pretreatment for the vapor phase growth.
The method includes a step of distributing diamond growth nuclei having a distribution density of 10 ¹⁰ cm ^-2 or more.

In another configuration according to the present invention, of the two electrodes provided so that electrons move along the surface of the diamond film, the electrode on the back side without the conductive layer is a Schottky junction with diamond, The electrode on the surface side with the conductive layer is characterized by being in ohmic contact with the surface conductive layer.

The above structure is characterized in that the electrode on the surface side with the electric layer is formed of a metal containing at least Ti.

Further, another configuration according to the present invention is characterized in that comb electrodes are provided on the front and back surfaces of the diamond thin film so as not to overlap each other.

According to another aspect of the present invention, there is provided a diamond thin film including a portion having n-type semiconductor characteristics,
One of the two electrodes provided on the diamond thin film is in ohmic contact with the portion of the diamond thin film having the n-type semiconductor characteristics.

FIG. 1 shows a conceptual diagram (cross-sectional view) of an electron-emitting device according to the present invention. A lower electrode 12 is formed on a part of the surface of the insulating substrate 11, and a diamond thin film 14 is formed on the lower electrode 12 and the exposed portion 13 on the substrate surface so as to extend over both. Another upper electrode 16 was formed with a gap 15 so that the upper portion of the diamond thin film 14 did not cover the lower electrode 12.
The surface of the diamond thin film 14 has a conductive layer 17, and the upper electrode 16 and the surface conductive layer 17 have the same potential, and the lower electrode 12
And the voltage applied to the upper electrode 16 is applied intensively in the thickness direction of the diamond thin film 14 on the lower electrode 12. The electrons 18 injected from the lower electrode 12 into the diamond thin film 14 by the concentrated electric field reach the surface conductive layer 17 and move toward the upper electrode 16 along the diamond thin film surface conductive layer 17 as shown by arrows in FIG. I do. Electrons running near this surface are very likely to fly out of the diamond thin film surface into a vacuum because the surface of the diamond conductive layer has a negative electron affinity (NEA).
In this case, when another third electrode 19 is provided, the potential difference between the third electrode and the surface conductive layer 17 causes
Electrons 18 are drawn into the vacuum.

In this case, it is preferable that the conductive layer on the surface of the diamond thin film is a hydrogenated diamond layer because the surface is conductive and exhibits a negative electron affinity, and electron emission is efficient.

As described above, the two electrodes provided so that electrons move along the surface of the diamond film are in contact with different portions of the diamond thin film, and there is a gap between the two electrodes, and both electrodes have If there is a portion of the diamond thin film that is not in contact, the electrons injected into the diamond thin film run on the surface of the diamond thin film, and during that time, the electrons are emitted into a vacuum by an electric field, so that the electron emission is efficient, which is preferable.

If the thickness of the diamond thin film is 10 nm or more, the lower electrode 12 and the diamond surface conductive layer 17
When the thickness is 5 μm or less, a voltage applied between the lower electrode 12 of the diamond layer and the surface conductive layer 17 of the diamond thin film causes a sufficient electric field to be applied to the diamond. It is preferable that electrons are efficiently supplied from the lower electrode 12 to the diamond layer 14 so that electrons are efficiently emitted.

In the above structure, a diamond thin film is grown by a vapor growth method, and 1x is used as a pretreatment for the vapor growth.
By including the step of distributing diamond growth nuclei having a distribution density of 10 ¹⁰ cm ^-2 or more, a diamond thin film having the above thickness range can be formed with good reproducibility, and the insulation between the lower electrode 12 and the diamond surface conductive layer 17 can be improved And the voltage can be applied, electrons are efficiently supplied from the lower electrode 12 to the diamond layer 14, and electrons are efficiently emitted, which is preferable.

Also, of the two electrodes provided so that electrons move along the surface of the diamond film, if the electrode on the back side without the conductive layer is Schottky-bonded to diamond, it will be between the electrode on the back side. A high electric field can be applied, electrons can be injected into diamond, and if the electrode on the surface side with the conductive layer is in ohmic contact with the surface conductive layer, the potential can be efficiently applied to the diamond surface conductive layer. Thus, a voltage can be applied between the lower electrode 12 and the diamond surface conductive layer 17.
This is preferable because electrons are efficiently supplied to 4 and electron emission occurs efficiently. In the above structure, if the electrode on the front side with the conductive layer is formed of a metal containing at least Ti, the electrode on the back side without the conductive layer is a metal that forms a Schottky junction with diamond, and the electrode on the front side with the conductive layer. Is preferably in ohmic contact with the surface conductive layer by the above configuration, and can achieve the above configuration.

Further, if the comb-shaped electrodes are arranged on the front and back surfaces of the diamond thin film so that they do not overlap each other, the gap 15 between the electrodes from which electrons are emitted is formed uniformly over a wide area, and uniform electron emission over a wide area is achieved. Obtained and preferred.

Also, the diamond thin film includes a portion having n-type semiconductor characteristics, and one of the two electrodes provided on the diamond thin film forms an ohmic junction with the portion of the diamond thin film having n-type semiconductor characteristics. In this case, injection of electrons from the electrode into the diamond thin film becomes easy, and efficient electron emission can be achieved, which is preferable.

In the above description, two electrodes are provided so as to sandwich a diamond thin film, such as a lower electrode and an upper electrode, but two electrodes are provided on one surface of the diamond thin film. Even in such a case, it is sufficient that electrons are injected into the diamond thin film and the electrons move along the surface of the diamond thin film.

[0031]

(Embodiment 1) Referring to FIG.
A first embodiment of the present invention will be described. Fused quartz substrate 11
A part of the surface is hidden by a metal mask, and the Pt electrode 12 is vacuum-evaporated.
It was formed by wearing. The base on which the lower electrode 12 is formed
The plate 11 was cleaned by ordinary organic washing, and the average particle size was 0.
Immerse in a solution in which 02 μm diamond particles are dispersed,
High density formation for diamond growth by applying ultrasonic vibration
Formed a long nucleus. The above diamond particle dispersion is
Add 2 g of diamond particles to the pure water of
Add a few drops of hydrofluoric acid after adding ethanol
The solution had a pH value of about 3. Sonicate for 10 minutes
The density of the diamond growth nuclei formed on the substrate surface is
5x10^TenPieces cm ^-2It was about. The above diamond growth nucleus
The formed substrate is placed in a microwave CVD device, and hydrogen
Supply diluted CO (1-10%) gas and power of several hundred W to 25-4
A diamond thin film was formed at a vacuum of 0 Torr. this
The substrate temperature in this case was 800-900 ° C.

A diamond thin film 14 having a thickness of 0.2 μm was formed by CVD growth for several minutes. In this case, the diamond was not consciously doped, so that an almost insulating diamond thin film was formed. In the as-deposited state, the surface of the diamond thin film 14 was hydrogenated, and the conductive layer 17 was present on the surface. An upper Ti electrode 16 was further formed on the diamond thin film by electron beam evaporation using a metal mask. In this case, the lower electrode 1
An electrode was formed with a gap 15 between the portion 2 and the upper electrode 16. The gap between the lower electrode 12 and the upper electrode 16 was 5 mm in width and 1 mm in gap.

An electron-emitting device using the formed diamond thin film is placed inside a vacuum device maintained at 10 ^-7 Torr or less, and a glass plate having a thickness of 1 mm and containing ITO on the surface and coating a phosphor on the surface is formed thereon. Was placed. A voltage of 100 V is applied so that the lower electrode 11 is negative and the upper electrode 16 is positive, and a potential of 7 kV, which is positive with respect to the upper electrode, is applied to the electrode 19 to obtain a current density of 1 μA / cm ² or more. Electron emission was confirmed.

In this case, an increase in electron emission was observed by doping P during the formation of the diamond thin film and using the diamond thin film as an n-type semiconductor. In this case, the lower electrode 12 used Ni. It was confirmed that the n-type diamond semiconductor and the Ni electrode were ohmic-coupled. In order to achieve the above configuration, it is possible to use a metal electrode other than those described above, and one of the electrodes in contact with the diamond thin film is formed between the diamond and a Schottky junction / or an n-type semiconductor portion of the diamond and an ohmic electrode. It is preferable that the electrodes are joined, and it is preferable that the other electrode is in ohmic contact with the surface conductive layer of diamond.

(Embodiment 2) A second embodiment of the present invention will be described with reference to FIG. On the surface of the fused quartz substrate 21,
Pt comb electrodes 22 were formed by vacuum evaporation. The substrate 21 on which the comb-shaped lower electrode 22 is formed is cleaned by ordinary organic cleaning, immersed in a solution in which diamond particles having an average particle size of 0.02 μm are dispersed, and subjected to ultrasonic vibration to provide a high-level for diamond growth. A density growth nucleus was formed. The above-mentioned diamond particle dispersion liquid was a liquid having a pH value of about 3 in which 2 g of diamond particles were added to 1 liter of pure water, 2 liters of ethanol was further added, and several drops of hydrofluoric acid were dropped.
The ultrasonic treatment was performed for 10 minutes, and the density of the diamond growth nuclei formed on the substrate surface was about 5 × ^{10 10} cm ⁻² . Microwave CV is applied to the substrate on which
A diamond thin film was formed in a D apparatus by supplying CO (1-10%) gas diluted with hydrogen and supplying a power of several hundred watts and a vacuum degree of 25-40 Torr. The substrate temperature in this case was 800-900 ° C. A diamond thin film 24 having a thickness of 0.2 μm was formed by CVD growth for several minutes. In this case, the diamond was not consciously doped, so that an almost insulating diamond thin film was formed. In the as-deposited state, the surface of the diamond thin film 24 was hydrogenated, and a conductive layer was present on the surface. An upper Ti comb electrode 26 was further formed on the diamond thin film by electron beam evaporation. In this case, the lower electrode 22 and the upper electrode 26
An electrode was formed with a gap 25 therebetween. Lower electrode 22
A gap between the upper electrode 26 and the upper electrode 26 was formed by a comb-shaped electrode having a width of 20 mm and a gap of 1 mm over an area of 20 × 20 mm ² in total.

An electron-emitting device using the formed diamond thin film is placed inside a vacuum device maintained at 10 ^-7 Torr or less, and a glass plate is formed 1 mm apart from the surface and contains ITO on the surface and a phosphor applied to the surface. Was placed. A voltage of 100 V is applied so that the lower electrode 21 is negative and the upper electrode 26 is positive, and a potential of 7 kV, which is positive with respect to the upper electrode, is applied to the electrode 19 to obtain a current density of 1 μA / cm ² or more. At 2
Uniform electron emission was confirmed in the area of 0mm x 20mm.

[0037]

As described above, according to the present invention, an electron emission surface of a diamond thin film, two electrodes provided so that electrons move along the diamond thin film surface, and electrons are extracted from the diamond surface. By including at least another electrode for applying an electric field, a highly efficient electron-emitting device can be realized.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing the structure and operation of an electron-emitting device according to the present invention.

FIG. 2 is another conceptual diagram of the structure of the electron-emitting device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Substrate 12 Electrode 13 Part where electrode is not formed 14 Diamond thin film 15 Gap between two electrodes 16 Electrode 17 Surface conductive layer 18 Electron 19 Another electrode 21 Substrate 22 Comb-shaped lower electrode 24 Diamond thin film 25 Between two electrodes Gap 26 Comb upper electrode

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Tetsuya Shiratori 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (10)

[Claims] 1. An electron emission surface of a diamond film, and an electron emission surface provided to move electrons along the diamond film surface.
An electron-emitting device, comprising: a component comprising one electrode and another electrode for applying an electric field for extracting electrons from the diamond surface. 2. The diamond thin film surface includes a conductive layer,
Of the two electrodes placed so that electrons move along the surface of the diamond film, one is formed on the back side without the conductive layer, and the other is formed on the front side with the conductive layer, and is electrically connected to the conductive layer. The electron-emitting device according to claim 1, wherein the electron-emitting device is connected to: 3. The two electrodes provided so that electrons move along the surface of the diamond film are in contact with different portions of the diamond film, there is a gap between the two electrodes, and neither electrode is in contact. 2. The electron-emitting device according to claim 1, wherein a portion of the diamond thin film exists. 4. The method according to claim 2, wherein the conductive layer on the surface of the diamond thin film is a hydrogenated diamond layer.
3. The electron-emitting device according to item 1. 5. The diamond thin film has a thickness of 10 nm or more and 5 μm.
The electron-emitting device according to claim 1, wherein: 6. The method according to claim 1, wherein the diamond thin film is grown by a vapor phase growth method, and includes a step of distributing diamond growth nuclei having a distribution density of 1 × ^{10 10} cm ⁻² or more as a pretreatment for the vapor phase growth. 6. The electron-emitting device according to 5. 7. Among two electrodes provided so that electrons move along the surface of a diamond film, the electrode on the back side without the conductive layer is a Schottky junction with diamond, and the electrode on the front side with the conductive layer is 2. The electron-emitting device according to claim 1, wherein the electron-emitting device has an ohmic junction with the surface conductive layer. 8. The electrode on the surface side with the conductive layer has at least
The electron-emitting device according to claim 7, wherein the electron-emitting device is formed of a metal containing Ti. 9. The electron-emitting device according to claim 1, wherein a comb-shaped electrode is provided on the front and back surfaces of the diamond thin film so as not to overlap each other. 10. A diamond thin film including a portion having n-type semiconductor characteristics, wherein the diamond thin film is provided on the diamond thin film.
2. The electron-emitting device according to claim 1, wherein one of the electrodes is in ohmic contact with a portion of the diamond thin film having n-type semiconductor characteristics.