Electroluminescent device and method of producing the same

Details Electroluminescent device and method of producing the same Electroluminescent device and method of producing the same

1998-03-02

2001-03-27

Yamnitzky, Marie (Department: 1774)

Stock material or miscellaneous articles

Composite

Of inorganic material

C428S917000, C428S701000, C428S702000, C428S212000, C313S509000, C427S066000, C427S070000, C427S255310, C427S255320, C427S255360, C427S255700

Reexamination Certificate

active

06207302

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority of the prior Japanese Patent Applications No. 9-49178 filed on Mar. 4, 1997, and No. 9-341462 filed on Dec. 11, 1997, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to electroluminescent (hereinbelow referred to as EL) devices that are used for various instruments of emissive-type segment displays and matrix displays, displays of various information terminals, and the like. The present invention also relates to methods for producing the same.
2. Related Arts
An EL device is typically formed by laminating a first electrode, a first insulating layer, a luminescent layer, a second insulating layer, and a second electrode on an insulating glass substrate in this order. The first and second insulating layers are made of silicon dioxide (SiO
2
), silicon nitride (SiN), silicon oxynitride (SiON), ditantalum pentaoxide (Ta
2
O
5
) or the like, and formed by a sputtering method, a vapor deposition method, or the like.
Further, JP-B2-64-5440 proposes an insulating layer having an aluminum oxide (Al
2
O
3
)/titanium oxide (TiO
2
) laminated structure (herebelow referred to as Al
2
O
3
/TiO
2
laminated layer) to improve a withstand voltage of an EL device. The Al
2
O
3
/TiO
2
laminated layer is formed by alternately laminating Al
2
O
3
layers and TiO
2
layers by an Atomic Layer Epitaxy (ALE) method.
Each of the Al
2
O
3
layers has insulating characteristics and each of the TiO
2
layers has conductive characteristics. Accordingly, the Al
2
O
3
/TiO
2
laminated layer withstands a high voltage. However, TiO
2
forming the TiO
2
layers is very sensitive to a temperature, and a resistivity of TiO
2
decreases enormously as the temperature rises. When the resistivity of TiO
2
decreases, each resistance of the TiO
2
layers in the Al
2
O
3
/TiO
2
laminated layer also decreases. This results in substantial deterioration of the voltage withstanding performance of the Al
2
O
3
/TiO
2
laminated layer.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned problem and an object of the present invention is to provide an EL device having a high withstand voltage stable against a change in temperature and a method of producing the same. More specifically, the object of the present invention is to provide an insulating layer with a laminated structure for an EL device having a withstand voltage stable against a change in temperature and a method of producing the same.
To achieve the above-mentioned object, an EL device according to the present invention includes an insulating layer having a laminated structure of first and second layers. The first layer includes an insulating material, and the second layer includes titanium oxide added with an element for mitigating a change in resistivity of the insulating layer relative to a change in temperature. Accordingly, the EL device has a high withstand voltage stable against the change in the temperature. Preferably, an atomic ratio of the element relative to the titanium in the second layer is in a range of 0.01 to 1. The element can be selected from a group consisting of calcium, barium, strontium, aluminum, lead, and magnesium. More preferably, the insulating material of the first layer has a resistivity larger than 1×10
10
&OHgr;cm.
The second layer may include a titanium oxide type material having a positive temperature coefficient of resistivity. In this case, the EL device has a high withstand voltage stable against the change in the temperature as well. The titanium oxide type material can be selected from calcium titanate, barium titanate, and strontium titanate.
The insulating layer of the present invention can be produced by alternatively laminating the first and second layers by the ALE method.


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patent: 4413022 (1983-11-01), Suntola et al.
patent: 4486487 (1984-12-01), Skarp
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patent: 0 637 087 A1 (1995-02-01), None
patent: 59-47879 (1984-11-01), None
patent: 1-18563 (1989-04-01), None

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