JPH04123792A - Light emitting element - Google Patents

Abstract

PURPOSE:To achieve a high brightness and a stability, and increase a reproducibility by applying voltages to a first conductor layer and a third conductor layer respectively taking a second conductor layer for a reference potential. CONSTITUTION:A thin film of Al for a conductor layer 5 is formed on a glass substrate 1 by a resistor wire heating, and organic insulation material of polyimide for an insulation layer 6 is then formed on an LB method. In addition, an Au thin film for a conductor layer 7 is formed by resistor wire heating, and low speed electron beam phosphor material of ZnO:Zn for a phosphor layer 8 is formed in an applying method. An Al thin film for a conductor layer 9 is finally formed by resistor wire heating. For an obtained element, a negative potential is applied to an Al thin film of an electrode, a positive potential is applied to the Al thin film of the electrode respectively using a DC voltage, taking the Au thin film of the electrode for a reference potential, thereby a good light emission by ZnO:Zn phosphor can be achieved.

Description

[Detailed Description of the Invention] [Industrial Application Fields] The present invention relates to light emitting devices, particularly light emitting devices that utilize MIM and phosphors, and can be used in all application fields of light emitting devices such as flat panel displays. be.

[Conventional technology] 2. Description of the Related Art Light emitting elements having an MIM structure are conventionally known.

This structure is shown in FIG. A first metal layer 2 such as A1 is formed on a substrate 1, an insulating layer 3 is formed on this surface, and a second metal layer 4 such as Au is further formed on this surface. Light emission is obtained by applying a voltage between the metal layer 2 and the second metal layer 4.

However, the emission spectrum of this light emitting element is 400-10
It is a very broad luminescence showing a range of 0On11,
Therefore, this light emitting element could not be used in display devices and the like that require elements of three primary colors with high brightness. Japanese Patent Laid-Open No. 6.3-232295 discloses a method for solving such problems. According to this, as shown in Figure 1 of the publication, by inserting a phosphor layer between the second electrode and the insulator layer, a specific wavelength determined by the phosphor is emitted, and at the same time, the insulator layer It is said that the electrons tunneled through the rays can also be directly excited, producing strong light emission.

However, in this configuration, the thickness of the formed insulator layer is 20
Since it is extremely thin at -302 mm, damage during formation of the phosphor layer cannot be ignored, resulting in problems with the stability and reproducibility of the device. In addition, the film thickness of the phosphor layer is very thin at 1O-2 (D).
Considering that in order to obtain sufficient properties as a phosphor, the particle size must be on the order of several microns, it can be predicted that sufficient luminous intensity will not be obtained with this film thickness. Furthermore, when considering excitation by tunneled electrons, the energy of the electrons is determined by the applied voltage; on the other hand, the energy of tunneled electrons is several eV.
Therefore, depending on the characteristics of the phosphor material used, it may not emit light.

[Problems to be Solved by the Invention] An object of the present invention is to provide a light-emitting element that has high luminance, is stable, and can be manufactured with good reproducibility.

[Means for Solving the Problems] The structure of the present invention for solving the above problems is a light emitting device as described in the claims.

FIG. 1 shows the structure of a device according to the present invention. In the present invention, by forming the phosphor layer in the position shown in the figure, damage to the insulator layer, which was a drawback of the prior art, can be avoided and a stable and reproducible element can be realized.

There are two possible ways to excite the phosphor: excitation by light emission from the MIM element and excitation by tunnel electrons.
In order to excite the phosphor layer 8 with tunneling electrons, the insulator layer 6 and the second conductive/electric layer 7 need to be very thin.

In particular, since electrons need to tunnel through the insulating layer, the film thickness is desirably from several to several hundred and fifty layers, preferably from 20 to 200 layers, and most preferably from about 20 to 100 λ. Furthermore, it goes without saying that it is necessary to exhibit insulation properties with a film thickness within the above range.

There are no particular restrictions on the method for manufacturing the insulator layer as long as it is possible to control the film thickness within the above range.

Furthermore, in the present invention, by providing the third conductor layer 9 and applying a bias of 10 to it, the tunneled electrons are accelerated, the excitation intensity of the phosphor is increased, and the emission intensity is improved. Furthermore, charging of electrons on the surface of the phosphor is avoided. There is no particular restriction on the accelerating voltage, but in consideration of practicality, it is preferably about several tens of volts.

In addition, as for the method for producing the phosphor layer, it is desirable that the method causes less damage to the underlying layer.

There are no particular restrictions on the material or manufacturing method of the third conductive layer, but a manufacturing method that does not cause much damage to the underlying phosphor layer is preferred.

There are no particular restrictions on the substrate, but if the direction in which light is extracted is from the substrate side, it must be translucent. In this case, the first conductor layer, the insulator layer, and the second conductor layer each need to have light-transmitting properties. Furthermore, when emitting light from the film formation side, the third conductive layer needs to have light-transmitting properties.

[Example code] Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 Here, a light emitting device having a device structure as shown in FIG. 1 was manufactured. As the substrate 1, a glass substrate was used. About 400 people formed an A1 thin film as the first conductor layer 5 on the substrate by heating with a resistance wire.

Next, about 30 to 50 people formed an insulator layer 6 of polyimide, which is an organic insulator material, by the LB method. Furthermore, the second
As the conductor layer 7, a thin Au film having a thickness of about 100 μm was formed by heating with a resistance wire, and as the phosphor layer 8, ZnO:Zn, which is a phosphor material for low-speed electron beams, was formed by a coating method.

Finally, as the third conductor layer 9, an A1 thin film with a thickness of about 1 μm,
It was formed by resistance wire heating.

The device thus fabricated was applied with a DC voltage using a second electrode, the Au thin film, as a reference potential, and a negative potential was applied to the first electrode, the A1 thin film, and a positive potential was applied to the third electrode, the AI thin film. . As a result, good light emission from the ZnO:Zn phosphor was obtained.

In this example, a polyimide film formed by the LB method was used as the material for the insulating layer, but the effects of the present invention are not limited to these, and similar effects can be obtained using other materials and manufacturing methods. Obtained.

Example 2 In this Example 2, instead of polyimide, which is the material of the insulator layer 6 of Example 1, an A1 thin film, which is a conductor layer, is heated in air at about 150 to 200°C for 40 minutes to form an AI A surface oxidation layer of approximately 30 to 50 layers was formed on the surface of the insulator layer 6, and the other conditions were the same as in Example 1 to produce an element.
Seven tests were conducted under the same conditions.

As a result, good luminescence of the ZnO:Zn phosphor was obtained.

In this example, Al2O produced by surface oxidation of the AI thin film, which is the first conductive layer, was used as the material for the insulating layer, but the effects of the present invention are not limited to this, and other materials may be used. Similar effects were obtained using other materials and other fabrication methods.

[Effects of the Invention] As explained above, the light emitting element of the present invention is stable, has good reproducibility, and can emit light with high brightness.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the structure of a light-emitting element of the present invention, and FIG. 2 is a schematic cross-sectional view showing the structure of a light-emitting element having a conventional MIM structure. DESCRIPTION OF SYMBOLS 1... Substrate, 2... First metal layer, 3... Insulator layer, 4... Second metal layer, 5... First conductor layer,
6... Insulator layer, 7... Second conductor layer, 8
...phosphor layer, 9... third conductor layer.

Claims (2)

[Claims] (1) A first conductive layer and an insulating layer made of an organic material formed on the surface of the first conductive layer are formed on the substrate, a second conductive layer is formed on the surface of the insulating layer, and a fluorescent layer is formed on the surface of the second conductive layer. It has a light layer, further has a third conductor layer on its surface, and applies a voltage to each of the first conductor layer and the third conductor layer with the second conductor layer as a reference potential. A light-emitting element characterized in that a voltage is applied to the light-emitting element. (2) The light emitting device according to claim (1), characterized in that the first conductor layer has an insulator layer made of an inorganic material in place of the insulator layer made of an organic material on the surface of the first conductor layer.