JPS62272421A - Electron emitting element - Google Patents

Abstract

PURPOSE:To exceedingly improve the efficiency in an electron emission by forming minute projections on the electron emitting surface of a conductive material at the interface between the insulating layer and the conductive material. CONSTITUTION:When a voltage V is applied between a conductive material 1 and metal 4, a strong electric field is generated on minute projections 2. Electrons emitted from the minute projections 2 tunnel through an insulating layer 3 and are emitted from the electron emitting portion W of the metal 4. The tunneling electrons accelerated by the strong electric field has high enough to exceed the energy level in vacuum regardless of the scattering and energy loss in the insulating layer 2 and metal 4. Since a high probability of having the energy electric field is concentrated at the minute projections 2 and the concentration of the electric field at other portions is softened, almost no current flows which does not contribute to the electron emission. Therefore, it is possible to exceedingly improve the efficiency in the electron emission.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention has a structure in which a metal material is laminated on a conductive material with an insulator interposed therebetween, and the conductive material and an electron-emitting device that emits electrons from the surface of the metal material by applying a voltage between the metal materials (hereinafter referred to as a HIM-type electron-emitting device), particularly improving electron emission efficiency and extending the lifespan. The present invention relates to an electron-emitting device intended for.

[Prior art and its issues] FIG. 4 is a schematic diagram showing a general configuration of a 111% electron-emitting device.

As shown in the figure, the MIX type electron-emitting device is made of metal M
It has a structure in which a thin metal N2 is laminated on top of the metal N2 with a thin insulating layer 1 interposed therebetween. Then, by applying a voltage V larger than the functional function φl of the metal M2 between the metals M1 and 112, among the quanta tunneled through the insulating layer 2, those having energy higher than the vacuum level are transferred to the metal M2.
released from the surface.

In order to obtain high electron emission efficiency in such a device, it is desirable to form the insulating layer (2) as thin as possible within a range that does not cause dielectric breakdown, and within a range that allows sufficient current to flow through the metal M2.

FIG. 5 is a schematic cross-sectional view of a conventional HIM type electron-emitting device. As shown in the figure, in terms of electron emission efficiency, metal M2
is formed in a brocade pattern, increasing electron emission efficiency.

However, in such a conventional structure, there are electrons that tunnel from the metal layer through the insulating layer (2) and reach the gold IAM2 even in parts other than the electron-emitting part W, and the current in parts other than the electron-emitting part W is It hardly contributes to electron emission, and therefore the amount of electron emission becomes smaller than the current flowing through the electron-emitting device, making it impossible to improve electron emission efficiency.

Measures to solve problem C] The electron-emitting device according to the present invention is as follows.

Metal material sandwiched between an insulator and a conductive material! ! In the electron emitting device, which has an i-layer structure and emits electrons from the surface of the metal material by applying a voltage between the conductive material and the metal material, at the insulator interface of the conductive material. It is characterized in that minute protrusions are formed in a portion corresponding to the electron emitting surface.

[Function] Since the microprotrusions of such conductive material face the metal material through the insulator, when a voltage is applied between the conductive material and the metal material, a high electric field is concentrated on the microprotrusions. As a result, the current in the microprotrusion portion increases, and the current in other portions that do not contribute to electron emission is suppressed, resulting in a significant improvement in electron emission efficiency.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a schematic cross-sectional view of a first embodiment of an electron-emitting device according to the present invention.

In the same figure, is the surface of the conductive material 1 emitting electrons? B
In the portion corresponding to -, a microprotrusion portion 2 consisting of a large number of microprotrusions of 14 m or less is formed. Furthermore, a metal 4 is laminated on the conductive material 1 with an insulating layer 3 of about 50 to 150 layers sandwiched in between, and the portion where the metal is connected has a thickness of 20 to 3
It was formed to about 50 people.

This is an electron emitting section W. The range of electron emission efficiency is 50 meters or more.

The upper body is made of conductive material. Further, in the insulating layer 3, the conductive material l is A1? AJ'LlfA1203, Si tear h4fSiO2'
*17) An oxide insulator is preferable from the viewpoint of manufacturing. Furthermore, the metal 4 may be A1, Au, PT, or the like.

In this embodiment, when a voltage V is applied between the conductive material 1 and the metal 4, a strong electric field is generated in the microprotrusions 2, and electrons tunnel from the microprotrusions 2 through the insulating layer 3 to reach the metal 4. The electrons are emitted from the electron emitting section W.

At that time, the electrons tunneled by the strong electric field are
! Despite scattering and energy loss in :2 and metal 4, the proportion of energy sufficiently higher than the vacuum level increases. Furthermore, since a high electric field is concentrated only on the microprotrusions 2 and electric field concentration on other parts is relaxed, currents that do not contribute to electron emission loosen and stop flowing.

Due to these phenomena, even if the same voltage V as in the conventional example is applied, electron emission can be performed more efficiently than in the conventional example. On the other hand, since the electron emission becomes 11 at low applied voltage, the insulating layer 3
It can prevent dielectric breakdown and greatly extend the life expectancy.

FIG. 2 is a schematic cross-sectional view of a second embodiment of the invention.

As shown in the figure, even if a flat metal 5 is formed on the insulating layer 3, a high electric field is concentrated only in the portion of the microprotrusion 8112, so that the electrons in a limited range are A discharge part W can be obtained.

Next, a method for forming the minute protrusions 2 will be explained.

FIGS. 3(A) and 3(B) are schematic process diagrams showing an example of a method for forming microprotrusions.

First, as shown in FIG. 2A, a mask material 8 of about 14 m is patterned on the surface of the conductive material 1.

Subsequently, etching is performed under appropriate conditions to form microprotrusions 2 having a large number of microprotrusions of 1 lumen or less on the conductive material.

[Effects of the Invention] As explained in detail above, in the electron-emitting device according to the present invention, since the minute protrusions of the conductive material face the metal material via the insulator, the conductive material and the metal material When a voltage is applied between them, a high electric field is concentrated between the microprotrusions and the metal. As a result, the current in the microprotrusion portion increases, and the current in other portions that do not contribute to electron emission is suppressed, making it possible to significantly improve electron emission efficiency.

In addition, since electron emission is possible with a low applied voltage, a thin insulating layer can be used, improving electron emission efficiency and preventing dielectric breakdown of the insulating layer, significantly extending the lifespan. can be extended to

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a first embodiment of electron emission efficiency according to the present invention, FIG. 2 is a schematic cross-sectional view of a second embodiment of the present invention, and FIG. 3 (A) and CB) are , a schematic process diagram showing an example of a method for forming microprotrusions, FIG. 4 is a schematic diagram showing the general configuration of a HIM type electron-emitting device, and FIG. 5 is a schematic diagram of a conventional MIX-type electron-emitting device. FIG. l...Conductive material 2...Minute protrusions 3...Insulating layer 4.5...Metal agent Patent attorney Minoru Yamashita Child box 1 Figure 2 Figure 3

Claims (1)

[Claims] (1) It has a structure in which a metal material is layered on a conductive material with an insulator in between, and by applying a voltage between the conductive material and the metal material, electrons are emitted from the surface of the metal material. An electron-emitting device, characterized in that a minute protrusion is formed in a portion of the insulator interface of the conductive material that corresponds to an electron-emitting surface.