JPS62176093A - Thin film light emitting device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to thin film light emitting devices and electroluminescent displays, and can also be applied to displays for computer terminal shades.

BACKGROUND OF THE INVENTION Alkaline earth chalcogen compounds are being developed as a base material for the light-emitting layer of electroluminescent devices aiming at multicolor. One of them is alkaline earth sulfides. Thin film light emitting devices are known in which luminescent centers such as Ce and ELJ are added to srs, cas, etc.
arrOW, 11. E, C00Vert and C,
Digest 1984 SID In
t,Symp,(Society forInform
ation Display, Los Angeles
, 1977, P8B and V, 5hanker, S, Tan.
aka, M., Shiiki, H., Deguchi.

, H.Kobayashi' and H.5asak.
ura；＾pp1. Phys.

Lett, 45, 960 (1984)].

The other is alkaline earth selenide. 5rSe
There are thin film light emitting devices in which a luminescent center such as Ce or Eu is added to Ca5e or the like.

In these thin film devices, oxides such as Y20x, SiO2, Al203, Ta205, etc. are used as insulating layers. However, in these devices, there is a problem in that interaction occurs between the insulating layer and the light-emitting layer when a high voltage is applied, resulting in a decrease in luminance.

Purpose The present invention aims to solve the above-mentioned problems of the prior art and provide a multicolor EL element with high brightness, low voltage drive, low cost, and high reliability.

Structure To achieve the above object, the present invention has a structure in which an electrode is disposed on at least one surface of an alkaline earth chalcogen light emitting layer via a dielectric layer. This is a thin film light emitting device in which at least one of the layers is made of nitride.

The structure of the present invention for achieving the above object will be described below. The light emitting layer base material of the thin film light emitting device includes alkaline earth chalcogenides such as alkaline earth sulfides such as SrS, Cab, and BaS, alkaline earth metals such as Sr'Se and CaSe, and selenides. C as a luminescent center in this base material
By adding a lanthanoid rare earth element such as e1Eu, various luminescent colors can be obtained according to the combination U of [I I4 and the luminescent center. For example, 5rSe:C
In e, blue emission is cas; in ce, green emission or Ca
S: Eu emits red light as I8.

The present invention is characterized in that the insulating layer laminated with the light emitting layer is made of nitride. Nitrides include BN, AIN, and T.
Examples include iN, TaN, and Si3N4. These films can be fabricated by sputtering, ion blasting, vapor deposition, CV
It is produced by methods such as D.

The cause of the decrease in brightness when an oxide is used as an insulating layer is not clear. One possible cause is that oxygen in the insulating layer diffuses toward the light-emitting layer under high voltage and reacts with the light-emitting layer material 1, especially alkaline earth. Therefore, it is desirable to provide an insulating layer made of nitride on the side in contact with the light emitting layer.

The insulating layer in a thin film light emitting device may be provided on either the light emitting side or the back side of the light emitting layer, or may be provided on both sides to form a double insulation structure. In the case of the present invention, one side is also insulated,
Both sides can be insulated and both structures can be used. In either structure, it is desirable to provide a nitride insulating layer on the side in contact with the light emitting layer. By doing so, the reaction between the light emitting layer, especially the alkaline earth element, and the insulating layer can be suppressed, and a highly reliable light emitting element can be obtained. In this case, each insulating layer does not necessarily have to be a single layer. As mentioned above, if there is a nitride layer on the side in contact with the light-emitting layer, the reaction is suppressed, so it goes without saying that a stacked layer of nitride and oxide, for example, may be used. In this case, the oxide layer is Y2O3, 5i02, Al2
Paraelectric materials such as O3, Ta205, SrTiO3, PbT
! 03, PbNb2O6, or other ferroelectric materials can be used.

This thin film light emitting device is manufactured by sequentially laminating each layer on a glass substrate. A transparent electrode is first deposited on the glass substrate. Transparent electrode materials include ITO, Sn
O2GL S b, 1: etc. added, Z, n
A mixture of O and A1 added thereto is suitable. These transparent electrode layers are produced by sputtering, vapor deposition, CVD, or the like. Suitable film thickness is from several hundred to several thousand.

On this transparent electrode, an insulating layer may be laminated as described above, or a light emitting layer may be laminated. In order to suppress the reaction between the light emitting layer and the transparent electrode layer, it is desirable to provide an insulating layer on the transparent electrode. As the insulating layer, the above-mentioned single nitride layer or a laminated structure with nitride, oxide, carbide, etc. layers is suitable. In this case, a nitride layer is laminated on the side in contact with the light emitting layer. The insulating layer is manufactured by sputtering, vapor deposition, CVD,
This is done by ion plating, etc.

E and L light emitting layers are laminated on this insulating layer. As the light-emitting layer material, a material obtained by adding a rare earth element or the like to the above-mentioned alkaline earth chalcogenide is used. The method for producing the light emitting layer is E.
B vapor deposition, sputtering, reactive vapor deposition, ion blating, etc. are suitable. Furthermore, thin films can be fabricated by CVD, MOCVD, etc.

The thickness of the light-emitting layer is suitably from several thousand to several μm.

This light-emitting layer may have an insulating layer laminated thereon or a back electrode laminated thereon. When laminating insulating layers, they can be laminated in the same manner as described above. The thickness of these insulating layers is suitably from several hundred to several μm.

Next, a back electrode layer is laminated. Back electrode material is AI, Ti
Transparent electrodes such as metals such as ITO and ITO can be used.

These films are produced by vapor deposition, sputtering, CVD, or the like.

A film thickness of several hundred to several thousand is suitable.

A monochromatic thin film light emitting device can be manufactured by the above lamination process. When producing a multicolor light emitting device, structural units are laminated in which a light emitting layer corresponding to each color is sandwiched between insulating layers and electrodes. In this case, insulation between the units of the base 111ffU can be achieved by an oxide insulating layer, a nitride insulating layer, or the like.

In other words, this invention is based on the electroluminescence (
The decision was made to use nitride as the insulating layer of the EL device, which was based on the discovery that reaction with the alkaline earth compound in the light-emitting layer could be suppressed, resulting in a high-performance and highly reliable EL device.

To illustrate its specific configuration with reference to the accompanying drawings, a transparent electrode 2, a nitride insulating layer 3, a light emitting layer 4, a nitride insulating layer 3, and a back electrode 5 are sequentially formed on the surface of a glass substrate 1.

An example of an apparatus for manufacturing the above EL element is not shown in FIG. 6.7 Evaporation sources for materials such as electrodes, insulating layers, and light emitting layers.
．． 8. A filament 12 is provided in the opening of the evaporation source.
Alternatively, an ionization electrode 13 is provided.

A substrate 9 is provided opposite the evaporation source 6.7.8 so that the temperature can be controlled by a substrate heater 10, and a shutter 11 is provided between the substrate 9 and the evaporation source.

A voltage 2 is applied to the ionization electrode by an ionization power supply 14, and a bias voltage V+ is applied to the substrate 9 by a bias power supply 16.

The molecules thus evaporated from the evaporation source are ion-blated onto the substrate 9. 15 is an ionization current 81, and 17 is a bias current H1.

Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 A thin film EL cord having an insulating layer made of silicon nitride (Si3N4) was manufactured by the following steps.

First, a do[0 film was formed on a glass substrate 1 to a thickness of 500 Å by sputtering. On top of that, 3 i 3 N,s is deposited by ion blating F B
The insulating layer was formed to have a thickness of 2000i. The material for the insulating layer was 4N Si 3 N 4 powder pressed into a doublet shape. -F ionization process of 513N+ vapor using accelerated thermionic electrons is used.A bias voltage of -200V was applied to the substrate during film formation.The reaction atmosphere was nitrogen gas, and the pressure was 4X.
It was set to 10'pa.

The input RF power is 100W.

A 3r3e:Ce light emitting layer was deposited on the insulating layer thus produced. The light-emitting layer was fabricated by an ionized co-evaporation method using accelerated thermionic electrons. The thickness of the light emitting layer was 1 μm. The substrate temperature during film fabrication was 400° C., and the bias voltage (V+) shown in FIG. 2 was −100V. Further, the input ionization power [product of ionization voltage (V2) and ionization current (A2)] was set to 200W.

On top of this light emitting layer, a Si3N4 insulating layer is again placed to a thickness of 2000 mm.
Formed to become a person. The manufacturing conditions were the same as those for the first insulating layer. An aluminum electrode was roughly vapor-deposited on this insulating layer and subjected to E to complete the device.

Apply an alternating pulse voltage of 300 to the EL cord thus manufactured.
A forced deterioration test was conducted at an atmospheric humidity of 80° C. by applying voltage of V and 5 kllz. As a result, it was found that when the luminance was halved, the lifespan was doubled compared to a device with an insulating layer of Y20:l.

Example 2 A thin film EL device using boron nitride (BN) as an insulating layer was manufactured in the same manner as in Example 1.

The thickness of the BN layer was 2000λ. The substrate temperature during deposition of the BNN layer was 150°C. The bias voltage was -500V, the reaction atmosphere was nitrogen gas, and the reaction pressure was 4x 10'f]a
, the input RF power was ioow.

A 5rSe:Ce light-emitting layer was deposited on the insulating layer thus prepared in the same manner as in Example 1. A BN insulating layer was again formed to a thickness of 2000 Å on this light emitting layer. An aluminum electrode is evaporated on top of this insulating layer and an EL
Hydrogen completed.

Apply an alternating pulse voltage of 300V to this FL element.

A forced deterioration test was conducted at an ambient temperature of 80° C. by beating i:il at 5 kllz. As a result, it was found that the life of the insulating layer was approximately three times longer than that of the Y203 element. The maximum brightness of this device was about 1000 cd/m2. Furthermore, the emission spectrum of this device is shown in FIG.

Example 3 Thin films E and L with aluminum nitride (AIN>) as the insulating layer
A device was manufactured in the same manner as in Example 1. The thickness of the AIN layer was set at 2,000 people.

The substrate temperature during the AIN layer deposition was 300'C.

Bias voltage -500V, reaction atmosphere is nitrogen gas, reaction pressure is 4x 1O-2P a, input power is 100W
And so.

A 5rSe:Ce light-emitting layer was deposited on the insulating layer thus prepared in the same manner as in Example 1. On this light emitting layer, an AIN insulating layer was again formed to a thickness of 2000λ. An aluminum electrode is roughly deposited on this insulating layer and an EL
Hydrogen completed.

This EL hydrogen element alternating pulse voltage is 300V.

A forced deterioration test was conducted at an ambient temperature of 80° C. with an applied frequency of 5 kHz. As a result, it was found that the lifespan of this device was approximately three times longer than that of a device with an insulating layer of Y2O3. Also, the AIN film is 3i
It was found that the adhesive strength was superior to that of the 3N4 film, and it was difficult to peel off.

Example 4 Insulating layer made of silicon oxide (SiO2) and titanium nitride (TiN)
) A thin film EL device having a laminated structure was manufactured by the following steps.

First, an ITO film was formed on a glass substrate 1 to a thickness of 500 mm by sputtering. On top of that, SiO
Two insulating layers were formed by sputtering to a thickness of 1,000 layers. Roughly thereon, a TiN insulating layer was formed to a thickness of Iooo by ion-blating FB evaporation. The substrate temperatures for the insulating layer formation 1h5 are 150°C (SiO2) and 200'C (TiN), respectively. In the case of SiO2, the atmosphere is a mixture of argon and oxidation.
The pressure was 1×10'pa, and the RF power was 4kW. In the case of TiN, the bias voltage is -500v, the atmosphere is nitrogen gas, the reaction pressure is 3X 1O-2P a, and the input R
F power was 150W.

A 5rSe:Ce light-emitting layer was vaporized on the insulating layer thus prepared in the same manner as in Example 1. On this light emitting layer, a TiN insulating layer with a thickness of 100 mm and a 5i02 insulating layer with a thickness of 1000 mm were laminated again. An aluminum electrode was roughly deposited on this insulating layer to complete the EL hydrogen element.

Apply an alternating pulse voltage of 300V to this El element.

A forced deterioration test was conducted at an ambient temperature of 80'C with an applied voltage of 5kllZ. As a result, the lifespan was approximately twice as long as that of a device with an insulating layer of Y20y. Furthermore, compared to a device with an insulating layer of Si3N4, the driving voltage could be lowered by about 30%.

Example 5 As an insulating layer, silicon oxide (SiO2), phosphorus nitride (
BN), thin film using aluminum nitride (AIN)
The device was manufactured by the following steps.

First, an ITO film was formed on the glass substrate 1 to a thickness of 500 mm by sputtering. On top of that, a 3iQ2 insulating layer is applied to a thickness of 1000λ by sputtering.
It was formed to look like 4. Furthermore, a BN insulating layer was formed thereon to a thickness of 1000 Å by ion-blating EB deposition. A SiO2 insulating base was used, the base temperature was 150°C, the atmosphere was a mixture of argon and oxygen, the pressure was 1xlO-' Pa, and the RF power was <W. B
In the case of the N insulating layer, the substrate temperature was 150'C, the atmosphere was nitrogen gas, the pressure was 4 x 10'pa, and the power was ioow.

A cas:cu light emitting layer was deposited on the insulating layer thus prepared in the same manner as in Example 1.

The thickness of the light emitting layer was 1 μm. The substrate temperature during film fabrication was 4
The temperature was 00'C, and the bias voltage was -150V. The input ionization power was 200W.

On this light emitting layer, an AIN insulating layer was formed to a thickness of 2000 nm. Substrate temperature is 300'C, bias voltage is -booyJ atmosphere is nitrogen gas, reaction pressure is 4X10
-2Pa and RF power was 100W.

Further aluminization (
Then, the L-column was completed.

This [L element is applied an alternating pulse voltage of 300V, 5kllZ
A forced deterioration test was conducted at an ambient temperature of 80'C. As a result, the lifespan is about 3 times longer than that of an element with an insulating layer of Y2O3.
I turned 18.

Example 6 The same layer structure as in Example 1 was used, with the insulating layer being 13i 3N4 and the light emitting layer being cas: cc.
A 1tAEc device was fabricated.

The conditions for forming the insulating layer were as follows. As a raw material, 4N silicon nitride (3i:+N4) powder was pressed and solidified into a tablet shape. The temperature of the glass substrate is 350°C.

The reaction pressure during ion blating is 3x 10″l'
-orr, the atmosphere is argon. The applied RF power was 100 W, and the acceleration voltage was 300 V.

Ion blasting E was applied on the insulating layer thus prepared.
A cas:ce light emitting layer with a thickness of 1.2 μm was formed by B vapor deposition. At this time, the glue plate temperature was 400°C.

A Si3N4 insulating layer was again formed on this light emitting layer by ion blasting to a thickness of 2000 nm. An aluminum electrode was deposited thereon to complete the L element.

As with Example 1, it was found that the El element using the insulating layer produced in this way had a longer lifespan than the conventional one using Y203.

Example 7 A9 film E [with aluminum nitride (AIN>) as the insulating layer
The device was manufactured by the following steps.

First, an ITO film was formed on the glass substrate 1 to a thickness of 500i. Ion blasting [[
By steaming 3 and 1, an AIN insulation layer was formed with an insulation thickness of 2000 fi.

The material used for the insulating layer was 4N AIN powder pressed and solidified into a tablet shape.

The temperature of the glass substrate 1 having the ITO film was maintained at 350°C, and the reaction pressure during ion blating was 5xlO'.
Torr, atmosphere is argon, input RF power is 5
0W, and the acceleration voltage to the substrate was 200V.

Ion blasting E was applied on the insulating layer thus prepared.
A cas':ce light-emitting layer with a thickness of 1.2 μm was prepared using B@Sake. The substrate temperature at this time was 400°C.

Place the AIN insulating layer again on top of this light emitting layer.

The film was formed to have a film thickness of 2000× by template plating. An aluminum electrode was deposited thereon to complete the EL device.

An alternating pulse voltage of 300V was applied to the EL element produced in this way.
, 5 KHz was applied, and a forced deterioration test was conducted at an ambient temperature of 80°C. It was found that with the structure shown in the attached drawings, the lifespan is doubled when the luminance is halved compared to the insulating layer made of Y2O:l.

Furthermore, it was found that the device has a longer lifespan than an element using a 3 i 3 N 4 edge layer (actual score of 6).

Example 8 Layer similar to Example 6? f4 composition, the insulating layer is made of boron nitride (
A thin film EL device was fabricated.

Fabrication of 11 layers was performed as follows.

The raw material used was 4N BN powder pressed and solidified into a tablet shape. The temperature of the glass substrate is 400'C. The reaction pressure during ion plating is 3x 10'
T orr , the atmosphere is argon. The input RF power was 150W, and the acceleration voltage was 400V.

Similar to Example 1 of the EL hydrogen device using the thus produced absolute B layer, it was found that it was superior to the conventional device using Y2O3 in terms of life.

Furthermore, it was found that the life span was excellent compared to the element using the Si3N4 insulating layer (Example 6).

[Effects] As explained above, by using a nitride layer as the insulating layer of the element, an EL hydrogen element with high reliability of 11 can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the structure of a thin film light emitting device of the present invention, FIG. 2 is an explanatory diagram showing an example of a manufacturing apparatus for a thin film light emitting device of the present invention, and FIG. 3 is a second embodiment of the present invention. 2 is a graph showing an EL hydrogen emission spectrum prepared in FIG. DESCRIPTION OF SYMBOLS 1...Glass substrate, 2...Transparent electrode, 3...Insulating layer, 4...Light emitting layer, 5...Back type 1~, &, 7.
8... Evaporation source, 9... Substrate, 10... Substrate heater, 11... Scissetter, 12... Filament,
13... Ionization electrode, 14... Ionization power source, 1
5... Ionization ammeter, 16... Bias power supply, 1
7...Bias ammeter. Figure 1 Figure 2 Diagram length (mm)

Claims (1)

[Claims] A thin film light emitting device having a structure in which an electrode is disposed on at least one surface of an alkaline earth chalcogen light emitting layer via a dielectric material, characterized in that at least one layer of the dielectric layer is made of nitride. Thin film light emitting device.