JP2000219878A - Production of fluorescent substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a GalnN-based fluorescent substance having good brightness characteristics and capable of providing arbitrary light-emitting colors from blue to red. SOLUTION: Gallium nitrate is mixed with indium nitrate as aqueous solutions at a prescribed ratio. Ammonia is dropped to the solution while keeping the solution at 40 deg.C to afford hydroxide of In and Ga, which is then baked and H2O is removed therefrom and 1% ZnO is added as a dopamine thereto and these compounds are reacted in ammonia stream for 1 hr to provide Ga0.95In0.05N:Zn fluorescent substance. The particle diameter of the fluorescent substance is distributed in the range of 0.2 μm to 1 μm and has a round shape which is similar to normal fluorescent substance. GaN and InN uniformly form a solid solution at atomic level. Evaluation of crystallinity of the fluorescent substance by X ray diffraction method exhibits 0.192 integration width which is good result. When the fluorescent substance is mounted in the fluorescent display device and the relationship between the positive voltage and brightness of fluorescent substance layer is examined, the fluorescent substance exhibits excellent brightness characteristics than a fluorescent substance prepared by conventional production method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a GaInN-based phosphor, and more particularly to a method for producing a GaInN-based phosphor, which has a good luminance characteristic because GaN and InN are uniformly dissolved at the atomic level, and has an arbitrary color from blue to red. The present invention relates to a method for producing a GaInN-based phosphor capable of obtaining an emission color.

[0002]

2. Description of the Related Art In recent years, single crystals of GaN have been known as materials for LEDs and LDs that emit blue or green light with high luminance. As a method for obtaining the GaN, a method using Ga ₂ O ₃ as a starting material is known. In this method, the emission color obtained is a blue color close to purple.

In addition, Ga_1-xIn_xN: A, B (0 <x
<1, A = Zn, Mg, B = Si, Ge)
Is known as a phosphor capable of emitting light from blue to red.
Have been. Attempts to cause this phosphor to emit light with an electron beam
Practical use of this phosphor in powdered form
What has reached the territory is unknown. For example, this Ga
_1-xIn_xAs a method for producing an N: A, B-based phosphor, Ga
_TwoS_ThreeAnd In_TwoS_ThreeOf powdered phosphor using
However, there are practical problems with this method.
Was.

[0004]

That is, in the above method,
Ga_TwoS_ThreeAnd In_TwoS_ThreeAre different in the decomposition temperature, especially In
_TwoS_ThreeIs Ga_TwoS_ThreeDecomposes below the temperature at which it is nitrided
Is very difficult to control.
Was. In addition, the characteristics of the obtained phosphor are put to practical use.
Need to be improved.

As another method for producing this phosphor, G
Although there is a method using a ₂ O ₃ and In ₂ O ₃ , since the nitriding reaction is a gas phase reaction, Ga ₂ O ₃ (trigonal system, monoclinic system) and In ₂ O ₃ ( (Cubic system) has a problem that it is difficult to form a solid solution.

[0006] In addition, when synthesized using a commonly used flux, there is a problem that this is taken in at the time of nitriding reaction to inhibit light emission.

The present invention relates to a method for producing a GaInN-based phosphor, in which GaN and InN are uniformly dissolved at the atomic level so as to have a good luminance characteristic and to obtain an arbitrary luminescent color from blue to red. It is intended to be able to manufacture.

[0008]

According to a first aspect of the present invention, there is provided a method of manufacturing a phosphor, comprising the steps of: Ga _1-x In _x N: A, B (0 <x
<1, A = A, Zn, Mg, B = Si, Ge) A method of manufacturing a phosphor characterized by mixing In and Ga in a colloidal state and then nitriding.

According to a second aspect of the present invention, there is provided a method of manufacturing a phosphor, comprising the steps of Ga _1-x In _x N: A, B (0 <x <1, A = Z
In a method for producing a phosphor represented by (n, Mg, B = Si, Ge), a substance containing In and a substance containing Ga are mixed in a state smaller than the colloidal particles, and then nitrided. .

In a third aspect of the present invention, there is provided a method for manufacturing a phosphor, comprising: Ga _1-x In _x N: A, B (0 <x <1, A = Z
n, Mg, B = Si, Ge) a method for producing a phosphor represented by the formula: wherein a water-soluble compound of Ga and In is generated, and a hydroxide of Ga and In is simultaneously generated from the water-soluble compound; It is characterized in that the hydroxide is nitrided after firing.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a phosphor, comprising: Ga _1-x In _x N: A, B (0 <x <1, A = Z
n, Mg, B = Si, Ge), a method for producing a nitrate aqueous solution of Ga and In and adding a substance selected from the group consisting of urea and ammonia to the nitrate aqueous solution. It is characterized in that Ga and In hydroxides are simultaneously generated and precipitated, and the hydroxides are fired and then nitrided.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a phosphor according to the third or fourth aspect, further comprising:
After co-precipitating the hydroxide, a raw material containing a substance selected from the group consisting of A and B is added to the hydroxide, and the hydroxide is fired.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a phosphor according to the third or fourth aspect.
The hydroxide is coprecipitated with a raw material containing a substance selected from the group consisting of A and B.

[0014]

After sintering, In and Ga are coprecipitated in a colloidal state, for example, a hydroxide state, and then calcined, followed by nitriding. In and Ga are sufficiently mixed at the atomic level in the state of hydroxide, and when this is fired, H ₂ O is cut off to form an oxide. However, since each oxide of In and Ga has a different crystal system, In this state, the overall crystallinity is not good. Here, when the nitriding step is performed in a gas phase reaction, the gas passes through the substance well and the nitriding proceeds efficiently, so that a GaInN-based phosphor mixed well at the atomic level can be obtained.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, Ga ₂ O ₃ and In ₂ O
_The starting material is a substance in which ₃ is in a solid solution state. However, although Ga and In have the same crystal structure at the nitride level, they are easily mixed uniformly, but oxides and sulfides have different crystal structures and are therefore difficult to mix uniformly. Therefore, even if Ga ₂ O ₃ and In ₂ O ₃ having different crystal systems are fired at a high temperature, the obtained nitrides segregate with each other.
For this reason, GaN also has a different composition in a part, and it is not possible to control the atomic level with a specific composition ratio. That is, the emission color cannot be properly controlled. In addition, since both light emissions are emitted, the color purity deteriorates.

For this reason, Ga _1-x In _x N: A, B (0
<X <1, A = Zn, Mg, B = Si, Ge) As a raw material used for manufacturing a phosphor represented by GaInN
In order to form a solid solution state, a material containing In and Ga
It is desirable that the starting material is a material containing a compound having a size of not more than the colloid level and preferably being mixed at the atomic level. Therefore, in the present example, Ga, In
The raw material was coprecipitated in the form of a hydroxide and used as a raw material.

(1) Example 1 Ga nitrate and In nitrate were weighed at a predetermined ratio and mixed as an aqueous solution. By dropping ammonia while keeping the temperature of the solution at 40 ° C., a hydroxide containing In and Ga was obtained.

By firing this hydroxide, H ₂ O
1% of ZnO as a dopant is added to a raw material having a composition ratio of x = 0.05 obtained by removing
The reaction was carried out at 50 ° C. for 1 hour to obtain a Ga _0.95 In _0.05 N: Zn phosphor. As shown in the SEM photograph of FIG. 1, the obtained phosphor had a particle size distribution ranging from 0.2 μm to 1 μm, and the shape was a rounded shape similar to a normal phosphor. .

An attempt was made to prepare a sulfide raw material as a starting material in the same manner as described above in which a hydroxide was coprecipitated. As a result of the investigation, a phosphor having a similar composition was obtained.

When the crystallinity of these phosphors was evaluated by the X-ray diffraction method, it was found that the integrated width was 0.272 (the smaller the better) as compared with 0.192 of the hydroxide raw material. The result was obtained.

As shown in FIG. 2, a fluorescent display device 1 (VFD1) was manufactured using the phosphor of this example. An anode conductor 3 which is a transparent electrode made of ITO or the like is provided on an anode substrate 2 made of glass. The phosphor of this example is applied on the anode conductor 3 by a screen printing method. This is fired at 500 ° C. in the air to remove the binder to form the phosphor layer 4, and the anode 5 composed of the anode conductor 3 and the phosphor layer 4 is formed on the anode substrate 2. The rear substrate 6 faces the anode substrate 2 at a predetermined interval, and a side plate is provided between the outer peripheral edges of both substrates 2, 6 to form an envelope 7. A filament-shaped cathode 8 and a control electrode 9 are both provided inside the envelope 7 sealed in a high vacuum state.

FIG. 3 shows the relationship between the anode voltage (anode voltage) and the luminance of the phosphor layer in the fluorescent display devices of the present example (the present application) and the comparative example (conventional example). As described above, the sample of the present application exhibited better luminance characteristics than the phosphor prepared by the conventional manufacturing method. The emission color at this time was blue.

(2) Example 2 Similarly, Ga, In nitrate was used, urea was added to the aqueous solution, and the temperature of the aqueous solution was maintained at 80 ° C. for 20 hours while stirring. Also with this method, a hydroxide precipitate containing In and Ga could be obtained.

By firing this hydroxide, H ₂ O
Was added as a dopant to a raw material having a composition ratio of x = 0.3, and 0.5% of MgCl ₂ was added as a dopant. 0.1% of polysilazane (trade name) was added as a Si raw material. ℃ in 2 hours of reaction, Ga _0.7 in _0.3
N: Mg, Si phosphor was obtained. The obtained phosphor had a particle size distribution in the range of 0.2 μm to 4 μm, and as a result of SEM observation, it had a rounded shape similar to a normal phosphor.

For comparison, an attempt was made to produce a phosphor by a conventional production method in which an oxide raw material was mixed.

As a result of X-ray diffraction of the obtained sample, the sample of this example had an integral width of 0.202. On the other hand, the comparative product was 0.354, and a single peak of GaN was confirmed.

As shown in FIG. 4, a field emission light emitting device 10 was manufactured using the phosphor sample of this example. First, a light-transmitting anode conductor 12 made of ITO or the like is provided on the inner surface of the anode substrate 11.
To form A phosphor screen is formed on the anode conductor 12 by a slurry method, and the mixture is baked at 520 ° C. to remove a binder to form a phosphor layer 13.
And an anode 14 composed of the phosphor layer 13. A cathode substrate 16 having a field emission cathode 15 is opposed to the anode substrate 11, and an outer peripheral portion of both substrates 11, 16 is sealed with a sealing material to form an envelope 17. The inside of 17 was evacuated and sealed to obtain a field emission light-emitting device 10. The field emission cathode 15 includes a cathode conductor 18 formed on a cathode substrate 16 and an insulating layer 19 formed on the cathode conductor 18.
A gate electrode 20 formed on the insulating layer 19; and a hole 2 formed in the gate electrode 20 and the insulating layer 19 in common.
1 and a cone-shaped emitter 22 formed on the cathode conductor 18 in the hole 21.

Evaluation was performed in the same manner as in the fluorescent display device of Example 1. The phosphor of this example emitted green light, and as shown in FIG. 5, it was found that the phosphor exhibited better characteristics than the conventional example (comparative example).

(3) Embodiment 3 The operation is performed in substantially the same manner as in Embodiment 1. As a raw material of a base material having a composition ratio of X = 0.8, G is used as a substance containing Ge as a donor.
e is added by 0.1% and coprecipitated as a hydroxide together with the base material. Mg as an acceptor is added to this raw material.
MgO is added as a substance containing 0.2%, and reacted at 950 ° C. for 2 hours in an ammonia stream to obtain Ga _0.2 In _0.8
An N: Mg, Ge phosphor was obtained. The obtained phosphor had a particle size distribution in the range of 0.2 μm to 4 μm, and as a result of SEM observation, it had a rounded shape similar to a normal phosphor.

When mounted on an FED having the same structure as in Example 2 and evaluated, red-orange light emission characteristics as shown in FIG. 6 were obtained. Further, for comparison, when a phosphor was produced by a conventional method using an oxide mixed raw material, the composition was segregated, and a desired emission color was not obtained.

In the production method of the present invention, the dopant raw material serving as an acceptor or a donor may be added before co-precipitation and co-precipitated with the hydroxide, or may be added after the hydroxide is precipitated. It may be fired together with the hydroxide, or may be added after the hydroxide is fired and before nitriding.

[0032]

According to the method for producing a phosphor according to the present invention, in the production of a GaInN-based phosphor, In and Ga are co-precipitated in a colloidal state, for example, a hydroxide state, and then fired. This is further nitrided.

Indium and Ga are sufficiently mixed at the atomic level in a hydroxide state, and when this is fired, H ₂ O is cut off to form an oxide, but each of In and Ga oxides has a crystal system. Due to the difference, the crystallinity as a whole is not good in this state. For this reason, in the nitriding step performed by the gas phase reaction, the gas passes through the substance well and the nitriding proceeds efficiently, and a GaInN-based phosphor that is well mixed at the atomic level can be obtained.

For this reason, by a simple manufacturing method, a high quality phosphor can be manufactured by selecting an arbitrary color from blue to red having better luminance characteristics than before.

[Brief description of the drawings]

FIG. 1 is a view showing an SEM photograph of a phosphor of Example 1 of the present invention.

FIG. 2 is a cross-sectional view of the fluorescent light emitting device according to the first embodiment of the present invention.

FIG. 3 shows a VFD of the first embodiment (the present application) and a VFD of a comparative example.
It is a figure which shows the anode voltage (anode voltage) -luminance characteristic of a (conventional example).

FIG. 4 is a sectional view of an FED according to a second embodiment of the present invention.

FIG. 5 shows the FED of Example 2 (the present application) and the FED of Comparative Example.
It is a figure which shows the anode voltage (anode voltage) -luminance characteristic of a (conventional example).

FIG. 6 shows an FED of Example 3 (the present application) and an FED of Comparative Example.
It is a figure which shows the anode voltage (anode voltage) -luminance characteristic of a (conventional example).

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Fumiaki Kataoka 629 Oshiba, Mobara-shi, Chiba Futaba Electronics Co., Ltd. (72) Inventor Hitoshi Toki 629 Oshiba, Mobara-shi, Chiba Futaba Electronics Co., Ltd. (72) Inventor Yuji Nomura 629 Oshiba, Mobara-shi, Chiba Futaba Electronics Co., Ltd. F-term (reference) 4H001 XA07 XA31 XA49 YA12 YA14 YA30 YA32

Claims (6)

[Claims] 1. Ga _1-x In _x N: A, B (0 <x <
1. A method for producing a phosphor represented by the formula (A = Zn, Mg, B = Si, Ge), wherein In and Ga are mixed in a colloidal state and then nitrided. 2. Ga _1-x In _x N: A, B (0 <x <
1. A method for producing a phosphor represented by the formula (A = Zn, Mg, B = Si, Ge), wherein a substance containing In and a substance containing Ga are mixed together in a state smaller than the colloidal particles and then nitrided. A method for producing a phosphor, comprising: 3. Ga _1-x In _x N: A, B (0 <x <
1. A method for producing a phosphor represented by the formula (A = Zn, Mg, B = Si, Ge), wherein a water-soluble compound of Ga and In is generated, and a hydroxide of Ga and In is simultaneously produced from the water-soluble compound. A method for producing a phosphor, which comprises producing, sintering, and nitriding the hydroxide. 4. Ga _{1 -x} In _x N: A, B (0 <x <
1. A method for producing a phosphor represented by the following formula: A = Zn, Mg, B = Si, Ge), wherein a nitrate aqueous solution of Ga and In is generated, and a substance selected from the group consisting of urea and ammonia is converted to the nitrate aqueous solution. A method for producing a phosphor, characterized in that Ga and In hydroxides are simultaneously produced and precipitated by adding to the above, and the hydroxides are fired and then nitrided. 5. The method according to claim 1, wherein said hydroxide is coprecipitated.
5. The method for producing a phosphor according to claim 3, wherein a raw material containing a substance selected from the group consisting of B and B is added to the hydroxide, and the hydroxide is fired. 6. The method according to claim 3, wherein the hydroxide is co-precipitated with a raw material containing a substance selected from the group consisting of A and B.