JPH11232999A - Electron-emitting device - Google Patents

Abstract

[PROBLEMS] To be applicable to an electron beam source for a display, an emitter portion of a micro vacuum device capable of high-speed operation, and the like.
Provided is a high-efficiency electron-emitting device that efficiently supplies electrons to a diamond layer by suppressing conduction of holes in electric conduction and emits an electron beam from a diamond surface. SOLUTION: An electron injection electrode, a hole blocking semiconductor layer formed of an n-type semiconductor, and an electron injection formed of a semiconductor having a narrower band gap than the semiconductor forming the hole blocking layer. It has a semiconductor layer and a diamond layer, and emits electrons from the surface of the diamond layer.

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.

According to the present invention, in order to solve the above-mentioned problems in the prior art, an electron supply layer for supplying electrons to a diamond layer having a surface from which electrons are emitted is formed. The object of the present invention is to provide an electron-emitting device that suppresses the conduction of holes in electrical conduction by efficiently providing electrons to the diamond layer and emits an electron beam from the diamond surface by providing a hole-blocking semiconductor layer in the semiconductor device. And

Further, the present invention has a laminated structure including at least an electrode layer and a diamond layer, and supplies electrons from the electrode layer to the conduction band of the diamond layer to thereby efficiently emit an electron beam. It is intended to provide an element.

[0013]

In order to achieve the above object, an electron-emitting device according to the present invention comprises at least an electron injection electrode and a hole blocking semiconductor layer made of an n-type semiconductor which are in contact with each other. And an electron injection semiconductor layer formed of a semiconductor having a narrower band gap than the semiconductor forming the hole blocking layer, and a diamond layer, and emits electrons from the surface of the diamond layer.

Further, the present invention is characterized in that, in the above-mentioned device, the electron injection electrode and the hole blocking semiconductor layer are in ohmic junction.

Further, the present invention is characterized in that, in the above device, the electron injection semiconductor layer is doped with p-type.

Further, the present invention is characterized in that in the above-mentioned element, the electron emission surface of the diamond surface has conductivity.

Further, the present invention is characterized in that the conductive electron emission surface of the diamond surface in the device is a hydrogenated diamond thin film surface.

According to the present invention, in the above-described device, a voltage is applied between the electron injection electrode and the surface of the conductive electron emission diamond, and electrons move from the electron injection electrode toward the electron emission surface. An electric field that emits electrons from the electron emission surface is applied to the surface.

Further, the present invention is characterized in that, in the above device, the hole blocking semiconductor layer is made of 6H-SiC or 4H-SiC, and the electron injection semiconductor layer is made of 3C-SiC.

Further, the present invention is characterized in that, in the above device, the hole blocking semiconductor layer is made of 4H-SiC, and the electron injection semiconductor layer is made of 6H-SiC.

Further, according to the present invention, in the above device, the hole blocking semiconductor layer is made of a nitride of a group III element such as GaN, and the electron injection semiconductor layer is made of 6H-SiC, 4H-SiC, 3C-SiC.
And the like.

Further, according to the present invention, in the above device, the electron injection electrode may be one of Ni, Ti, Cr, Mo, Ta, W, Al, Si, Pt, Au and Cu.
It is characterized by being constituted by a species, a nitride thereof, or a mixture of a plurality of substances among them.

FIG. 1 shows a band diagram of the electron-emitting device of the present invention. As shown in FIG. 1A, the electron supply electrode 1
1. n-type semiconductor layer 12, which is a hole blocking layer;
The electron supply semiconductor layer 13 and the diamond layer 14 having a narrower band gap than the semiconductor layer 12 of the hole blocking layer are in contact with each other to form a laminated structure, thereby forming the electron-emitting device of the present invention. Electron emission surface 15 of diamond layer 14
The vicinity 16 is p-type, and the surface 15 has a negative value with respect to the vacuum rank 17 and indicates a negative electron affinity (negative electron affinity: NEA). In this case, it is preferable that the electron supply layer 13 is p-type as shown in FIG. FIG. 1B shows a case where an electric field is applied to this laminated structure. As apparent from FIG. 1B, the conduction band 18 of each layer of the multilayer structure is smoothly connected from the electron supply layer electrode 11 to the surface 15 of the diamond layer 14, and the electron e is connected to the electron supply electrode 11. From the electron emission surface 15. On the other hand, the valence band 19 has a barrier 1 G between the electron supply semiconductor layer 13 and the hole blocking layer 12, and the hole h that travels from the diamond layer 14 toward the electron supply layer electrode 11 is formed between the electron supply semiconductor layer 13 and the hole blocking layer 12. Trapped by the barrier 1G between the blocking layers 12, the conduction is inhibited.

With the above mechanism, the supply of the electrons e from the electron supply electrode 11 toward the electron emission surface 15 is efficiently performed without being hindered by the conduction of the holes h in the opposite direction, and the electron emission occurs efficiently. .

In this case, it is preferable that the electron injection electrode and the hole blocking semiconductor layer have an ohmic junction, since electrons are efficiently injected from the electron injection electrode into the hole blocking semiconductor layer.

Further, when the electron injecting semiconductor layer is doped with p-type, the conduction band of the electron injecting semiconductor layer and the conduction band of diamond are smoothly connected, and electrons are efficiently transferred from the electron injecting semiconductor layer to the diamond layer. Supplied and preferred.

Further, it is preferable that the electron emission surface of the diamond surface has conductivity because an electric field for promoting injection of electrons from the electron injection electrode into the diamond layer can be efficiently applied. Also, the diamond surface with conductivity shows a negative electron affinity, and electrons are emitted from the surface without barrier,
It is preferable because efficient electron emission can be realized.

Further, when the conductive electron emission surface of the diamond surface is a hydrogenated diamond thin film surface, the diamond surface exhibits a negative electron affinity, and electrons are emitted from the surface without a barrier. Release can be realized and is preferred.

A voltage is applied between the electron injecting electrode and the surface of the conductive electron emitting diamond, electrons move from the electron injecting electrode toward the electron emitting surface, and further emit electrons from the electron emitting surface. By adopting a configuration in which such an electric field is applied to the surface, an efficient electron-emitting device can be achieved, which is preferable.

The hole blocking semiconductor layer is made of 6H-S
iC or 4H-SiC, electron injection semiconductor layer is 3C-S
By adopting the structure composed of iC, the bandgap of the semiconductor in the hole blocking layer becomes larger than the bandgap of the electron-injecting semiconductor layer, and the hole blocking barrier 1G of FIG. 1 is formed to conduct only electrons. As a result, an efficient electron-emitting device can be achieved, which is preferable.

The hole blocking semiconductor layer is 4H-S
By taking a structure composed of iC and the electron injection semiconductor layer composed of 6H-SiC, the forbidden band width of the semiconductor of the hole blocking layer becomes larger than the forbidden band width of the electron injection semiconductor layer. Hole blocking barrier 1G
Is formed, and conduction of only electrons occurs, and an efficient electron-emitting device can be achieved, which is preferable.

The hole blocking semiconductor layer is made of GaN.
Forbidden semiconductors in the hole blocking layer by adopting a structure composed of a nitride of a group III element such as III and an electron injection semiconductor layer composed of silicon carbide such as 6H-SiC, 4H-SiC, 3C-SiC. The band width is larger than the forbidden band width of the electron-injecting semiconductor layer, and the hole blocking barrier 1G shown in FIG. 1 is formed, so that only electrons are conducted, and an efficient electron-emitting device can be achieved.

The electron injecting electrode is made of Ni, Ti, Cr, Mo, Ta, W, A
By taking a structure composed of one of l, Si, Pt, Au, and Cu, or a nitride thereof, or a mixture of a plurality of these substances, an electron injection electrode and a hole blocking semiconductor can be obtained. This is preferable because the layers form an ohmic junction, electrons are efficiently supplied from the electron injection electrode to the hole blocking layer, and an efficient electron-emitting device can be achieved.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG.
As Ni and n-type 4H-S as the hole blocking layer 12
iC, p-type 6H-SiC as the electron supply semiconductor layer 13, the diamond layer 14 is an intrinsic diamond semiconductor layer, the electron emission diamond layer surface 15 is terminated with hydrogen, and the p-type diamond surface conductive layer 16 is formed. .

Specifically, as shown in FIG. 2, an n-type 10 mm × 10 m
0.5 μm Ni electrode 11 on the back of 4H-SiC substrate 12
An electron beam is vapor-deposited at a thickness of m and heat treated at 1000 ° C. to obtain an ohmic electrode, and a 6 μm-thick 6H-SiC thin film 13 is heteroepitaxially grown on the surface of a 4 μm-thick 4H—SiC substrate 12.
Heteroepitaxial growth was performed at 1500 ° C. on a 4H—SiC substrate containing no off by a CVD method in which silane and propane gas were diluted with hydrogen and flowed. 4H-SiC Hunt Cap
The band gap of 3.09 eV, 6H-SiC is 2.86 eV, and the band gap of 6H is smaller than that of 4H. Here, the Ni electrode functions as the electron supply electrode 11 of FIG. 1, the 4H-SiC substrate functions as the hole blocking layer 12, and the 6H-SiC layer functions as the electron supply semiconductor layer 13. This 6H-SiC / 4H-SiC layered structure forms a barrier 1G when a voltage is applied, as shown in FIG. 1 (b). A diamond thin film 14 having a thickness of 1 μm was formed on the surface of the 6H-SiC / 4H-SiC layered structure by a microwave CVD method using carbon monoxide diluted with hydrogen as a raw material. Since doping was not performed on diamond, an intrinsic semiconductor diamond thin film 14 was formed. The surface of the diamond thin film was hydrogenated to form the surface conductive layer 16 and exhibited p-type electric conduction. This electron-emitting device was held in a vacuum vessel, an electrode 21 was attached to a part of the diamond surface layer conductive layer as the electron-emitting surface 15, and a voltage of 300 V was applied between the electrode 21 and the Ni electrode as the electron supply electrode 11. . When a voltage of 7 kV is applied to the electrodes 22 placed 1 mm apart from the electron emission surface 15 of the electron emission element, a vacuum 17
An emission current (emission current) of 100 nA into the substrate was confirmed. It was confirmed that more than 0.01% of the current flowing between the electrode on the electron emission surface and the Ni electrode on the back surface of the 4H-SiC substrate was emitted.

In this embodiment, only the case where Ni was used as the electron supply electrode layer was described. However, the formation of ohmic junction was confirmed for the other electron supply electrode materials described in the claims of the present invention. The release effect was confirmed.

In this example, only the case of 4H-SiC was described as the hole blocking layer. However, the same electron emission effect was confirmed for the other materials of the hole blocking layer described in the claims of the present invention.

In this embodiment, only the case where 6H-SiC is used as the electron injecting semiconductor layer has been described. However, the same electron emission effect was confirmed for other materials of the hole blocking layer described in the claims of the present invention. . Further, the material of the hole blocking layer and the electron injecting semiconductor layer is not limited to the above substances, the forbidden band width of the semiconductor of the hole blocking layer is larger than the forbidden band width of the electron injecting semiconductor layer,
If the hole blocking barrier 1G of FIG. 1 is formed, efficient electron emission is achieved.

[0039]

As described above, according to the present invention, an electron supply layer for supplying electrons to a diamond layer having a surface for emitting electrons is formed, and a hole is provided between the electron supply layer and the electron injection electrode. By providing the blocking semiconductor layer, conduction of holes in electric conduction can be suppressed, electrons can be efficiently supplied to the diamond layer, and an electron beam can be emitted from the diamond surface.

Further, the present invention has a laminated structure including at least an electrode layer and a diamond layer, and supplies electrons from the electrode layer to the conduction band of the diamond layer to efficiently emit an electron beam. An emission element can be realized.

[Brief description of the drawings]

FIG. 1 is a band diagram showing the operating principle of the electron-emitting device of the present invention. FIG. 1 (a) is a diagram showing an equilibrium state.

[Explanation of symbols]

 Reference Signs List 11 electron supply electrode 12 hole blocking semiconductor layer 13 electron supply semiconductor layer 14 diamond layer 15 electron emission surface 16 near electron emission surface (surface conductive layer) 17 vacuum order 18 conduction band 19 valence band 1G hole blocking barrier

 ──────────────────────────────────────────────────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 injection electrode, a hole blocking semiconductor layer formed of an n-type semiconductor, and an electron formed of a semiconductor having a narrower band gap than the semiconductor forming the hole blocking layer. An electron-emitting device comprising an injection semiconductor layer and a diamond layer, and emitting electrons from the surface of the diamond layer. 2. The electron-emitting device according to claim 1, wherein the electron injection electrode and the hole blocking semiconductor layer have an ohmic junction. 3. The semiconductor device according to claim 1, wherein the electron injection semiconductor layer is made of a semiconductor doped with p-type.
An electron-emitting device according to claim 1. 4. The electron-emitting device according to claim 1, wherein the electron-emitting surface on the diamond surface has conductivity. 5. The electron-emitting device according to claim 4, wherein the conductive electron-emitting surface of the diamond surface is a hydrogenated diamond thin film surface. 6. A voltage is applied between an electron injection electrode and a conductive electron emission diamond surface, electrons move from the electron injection electrode toward the electron emission surface, and electrons are emitted from the electron emission surface. 2. An electron-emitting device according to claim 1, wherein an electric field is applied to the surface. 7. The electron-emitting device according to claim 1, wherein the hole blocking semiconductor layer is made of 6H-SiC or 4H-SiC, and the electron injection semiconductor layer is made of 3C-SiC. 8. The electron-emitting device according to claim 1, wherein the hole blocking semiconductor layer is made of 4H-SiC, and the electron injection semiconductor layer is made of 6H-SiC. 9. The method according to claim 1, wherein the hole blocking semiconductor layer is made of I
The electron injection semiconductor layer is composed of a nitride of a group II element.
2. The electron-emitting device according to claim 1, wherein the electron-emitting device is made of silicon carbide such as 6H-SiC, 4H-SiC, and 3C-SiC. 10. An electron injection electrode comprising Ni, Ti, Cr, Mo, Ta, W, Al,
2. The electron-emitting device according to claim 1, comprising one of Si, Pt, Au, and Cu, or a nitride thereof, or a mixture of a plurality of substances.