JP3760650B2 - GaN phosphor manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a Ga _1-x In _x N: A, B (0 ≦ x <1, A = Zn, Mg, B = Si, Ge) phosphor.
[0002]
[Prior art]
In recent years, GaN has been known as a material that emits blue and green high luminance light emitting elements such as LEDs and LDs in the case of a single crystal. Further, in the case of being represented by the general formula Ga _1-x In _x N: A, B (0 ≦ x <1, A = Zn, Mg, B = Si, Ge), a wide range from blue to red Can emit light.
[0003]
Conventionally, in order to manufacture a GaN phosphor, a Ga compound as a raw material is mixed with a compound of a doping material, and this is placed in a firing furnace and baked at a high temperature while flowing ammonia to nitride and Ga. Dope material.
[0004]
There have been attempts in the past to emit light from the material thus obtained with an electron beam, but no practical luminance has been achieved with respect to a phosphor in powder form.
[0005]
[Problems to be solved by the invention]
Unlike the other phosphor materials, the biggest reason why the luminance cannot be obtained is difficulty in nitriding. That is, since this material has a small difference between the nitriding temperature (700 ° C. to 1000 ° C.) and the temperature at which decomposition starts (950 ° C. or more), nitriding and decomposition are likely to proceed simultaneously in a normal heating reaction. For this reason, although GaN can be produced, GaN having such a high crystallinity that it can be used as a phosphor cannot be produced.
[0006]
In addition, the gallium nitride phosphor needs to be doped with gallium nitride as a donor and acceptor doping material for pair emission by a donor having a valence one higher than Ga and an acceptor having a valence one less than Ga. Even when doping a doping material, a higher temperature is required. However, as described above, since GaN is easily decomposed at a high temperature, the temperature cannot be increased and sufficient doping cannot be performed.
[0007]
Further, in order to obtain a nitride such as GaN, generally, a Ga compound as a raw material is baked and nitrided at a high temperature in an atmosphere using ammonia. At this time, hydrogen generated by decomposition of ammonia is used. Has a powerful reducing action. This reduction action reduces GaN and liberates Ga. Also, due to this reduction action, the doped material mixed with GaN is decomposed and scattered before diffusing into GaN, and the doped material cannot be sufficiently diffused. In order to prevent such an adverse effect of reduction by hydrogen, the reaction needs to be performed at a low temperature. However, this makes it impossible to dope the GaN into the GaN. Because of such problems, the conventional manufacturing method cannot obtain a GaN-based phosphor that can emit light with satisfactory luminance.
[0008]
An object of the present invention is to provide a method for producing a GaN-based phosphor that emits light with practically sufficient luminance by excitation of an electron beam.
[0009]
[Means for Solving the Problems]
The method for producing a GaN phosphor according to claim 1 is a method for producing a GaN phosphor represented by Ga _1-x In _x N: A (0 ≦ x <1, A = Zn, Mg) . Inside the firing furnace in which NH ₃ gas is allowed to flow in a predetermined direction, the compound of A that contains a substance arbitrarily selected from S and O as an element that reacts with H ₂ and is gasified by heating is disposed upstream. , characterized in that the firing base element compounds comprising said compounds arranged on the downstream side, while suppressing the reduction action of hydrogen in an atmosphere containing the a was arbitrarily selected material and gasified from S and O It is said.
[0011]
Method of manufacturing a GaN phosphor of claim 2, claim in the manufacturing method of the GaN phosphor according 1, the hear compounds before being placed into the upstream _{side, ZnS, ZnSO 4, ZnO,} ZnCO 3, It is a substance selected from the group consisting of MgS, MgSO ₄ , and MgCO ₃ .
[0012]
According to a third aspect of the present invention, there is provided a method for producing a GaN phosphor according to the first aspect, wherein the A contains Zn in an amount of 0.002 to 1 atm%.
[0013]
The method for producing a GaN phosphor according to claim 4 is the method for producing a GaN phosphor according to claim 1, wherein the matrix element compound is heated at a relatively high temperature, and the compound of A is relatively It is characterized by heating at a low temperature.
[0014]
The method for producing a GaN phosphor according to claim 5 is characterized in that Ga _1-x In _x N: A, B (0 ≦ x <1, A = Zn, Mg, B = Si, Ge) In the phosphor manufacturing method, the inside of the firing furnace in which NH ₃ gas flows in a predetermined direction contains a substance arbitrarily selected from S and O as an element that reacts with H ₂ and is gasified by heating. A compound is arranged on the upstream side, a matrix element compound containing the compound and the compound of B is arranged on the downstream side, and a substance arbitrarily selected from S and O and hydrogen in an atmosphere containing gasified A It is characterized in that firing is performed while suppressing the reducing action due to.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
In order to solve the series of problems described above, the present inventors considered that it is necessary to crystallize GaN while suppressing decomposition of GaN, and to sufficiently diffuse the doped material. For this purpose, a method is required in which GaN is crystallized at a high temperature while suppressing the reduction action by hydrogen, and at the same time, the doping of the doping material is efficiently advanced at this high temperature.
[0016]
As a specific method, the tubular furnace 1 shown in FIG. 1 is used as a firing furnace. A heater 2 as a heating means is spirally wound around the tubular furnace 1, and the inside of the tubular furnace 1 can be set to an arbitrary temperature. However, the temperature is relatively high at the center (A) of the heating range around which the heater 2 is wound, and the temperature is relatively low at the end (B) of the heating range. Both ends of the tubular furnace 1 are open, and a gas necessary for the reaction can flow from one (upstream side) to the other (downstream side).
[0017]
Inside the firing furnace 1, a compound 3 of a doping substance that contains an element that reacts with H ₂ and is gasified by heating is placed at the end (b) of the upstream heating range. In addition, the Ga compound 4 which is a raw material of the base material of the GaN phosphor is disposed in the central portion (A) of the downstream heating range. While flowing NH ₃ gas, the inside of the tubular furnace 1 is heated by the heater 2. The compound 3 of the doping substance is heated at a relatively low temperature, and the Ga compound 4 is heated at a relatively high temperature.
[0018]
The compound 3 of the doping substance is decomposed and scattered by ammonia, and an atmosphere containing S, O and the doping substance is generated in the vicinity of the Ga compound 4. As a result, the reduction action by hydrogen in the vicinity of the Ga compound 4 is suppressed by S and O, so that GaN is hardly decomposed, and no problem occurs even at the relatively high firing temperature described above. Furthermore, since the periphery of the Ga compound 4 is covered with a doping material that is gaseous with ammonia, a sufficient amount of the doping material can be diffused into the generated GaN. For this reason, by increasing the firing temperature, a GaN phosphor having high crystallinity and sufficiently doped with a doped substance can be obtained. According to the GaN phosphor manufactured by such a method, sufficiently practical luminance can be obtained.
[0019]
【Example】
(1) Example 1
A method for manufacturing a GaN: Zn phosphor will be described.
Ga ₂ O ₃ is used as a Ga source material (matrix element compound). ZnS is used as a source material for Zn as a doping material. Specifically, ₃ g of Ga ₂ O ₃ and 0.6 g of ZnS are mixed well together and placed on a firing boat. As shown in FIG. 1, ZnS (compound 3 of a doping substance) is also arranged on the upstream side in the tubular furnace 1. At this time, the Ga source material 4 is placed in the soaking zone (region heated to a predetermined temperature), which is the substantially central portion (A) of the heating range of the tubular furnace 1. Since ZnS (dope compound 3) is likely to be scattered in a reducing atmosphere, it is disposed at the end (b) of the heating range where the temperature is lower than that of the soaking zone. Thereby, the ZnS scattering during baking is maintained. In this state, Ga source material was baked at 1150 ° C. for 2 hours while flowing 350 ml / min of ammonia to obtain a GaN phosphor. At this time, ZnS is heated to 1050 ° C.
[0020]
The obtained GaN phosphor was applied to an anode substrate of a VFD and evaluated by emitting light at an anode voltage of 30V. Furthermore, it apply | coated to the anode board | substrate of FED, it was made to light-emit by the anode voltage 400V and evaluated.
[0021]
Sufficient doping material was detected in the GaN phosphor. FIG. 2 shows the relationship between the amount of scattered ZnS and the amount of doped material (Zn) in the GaN phosphor. It can be seen that the amount of the doping substance in the GaN phosphor can be controlled by increasing or decreasing the ZnS scattering amount in the upstream portion of the GaN gas in the furnace.
[0022]
FIG. 3 shows the relationship of luminance with respect to the amount of Zn in GaN. Usually, Zn concentration of 0.002% or more is necessary to obtain high luminance. When ZnS is not scattered in the furnace, Zn is not doped into GaN as indicated by 0 mol on the horizontal axis in FIG. 2, and high luminance cannot be obtained as indicated by the vertical axis. The range of the necessary Zn doping amount is preferably 0.002% to 1%.
[0023]
(2) Example 2
A method for producing a GaInN: Mg phosphor will be described.
2 g of Ga ₂ S ₃ which is a matrix element compound, 1 g of In ₂ S ₃ which is a matrix element compound, and 0.4 g of MgS which is a compound of a doping substance are mixed well and placed on a firing boat. A mixture of a base element compound such as Ga ₂ S ₃ and MgS that is a compound of a doping substance are placed in the tubular furnace 1 in the same manner as in Example 1. When the raw material was baked for 3 hours at a temperature of 1100 ° C. while flowing ammonia at 350 ml / min, a GaInN: Mg phosphor was obtained. Sufficient Mg diffusion was confirmed in this GaInN phosphor. As in Example 1, when mounted on a VFD or FED and evaluated, green light emission was obtained.
[0024]
(3) Example 3
S to place the phosphor upstream section, as a compound of the dopant containing _{O, ZnO, ZnSO 4, ZnCO} 3, MgSO 4, even when used by selecting any substances from MgCO _3, Examples 1 and 2 And substantially the same effect. ZnO, the case of _{ZnSO 4, ZnCO 3, ZnSO 4} , MgCO 3, since decomposes easily scattered in a reducing atmosphere, it is necessary to arrange the lower temperature region than ZnS.
[0025]
(4) Example 4
A method for manufacturing a GaN: Zn, Si phosphor will be described.
2 g of Ga ₂ S ₃ as a source material of Ga, 0.4 g of ZnS as Zn, and 0.0003 g of SiO ₂ as Si are mixed well and placed on a firing boat. A mixture of Ga ₂ S ₃ or the like as the matrix element compound is placed in the center of the tubular furnace in the same manner as in Example 1, and ZnS as the compound of the doping substance is placed further upstream. By firing ammonia at 350 ml / min for 2 hours at 1150 ° C., a GaN: Zn, Si phosphor was obtained. Sufficient Zn and Si diffusion was confirmed in this GaN: Zn, Si phosphor. As in Example 1, when mounted on a VFD or FED and evaluated, blue light emission was obtained.
[0026]
(5) Example 5
A method for manufacturing a GaInN: Zn, Ge phosphor will be described.
As raw materials, ₂ g of Ga ₂ S ₃ , 1 g of In ₂ S ₃ , 0.4 g of ZnS as Zn, and 0.0005 g of GeO ₂ as Ge are mixed well and placed on a firing boat. A mixture of Ga ₂ S ₃ or the like, which is the matrix element compound, is placed in the center of the tubular furnace in the same manner as in Example 1, and ZnS, which is a compound of a doping substance, is further arranged upstream of the mixture. Firing was performed at 1100 ° C. for 3 hours while flowing ammonia at 350 ml / min to obtain a GaInN: Zn, Ge phosphor. Sufficient Zn and Ge diffusion was confirmed in this GaInN: Zn, Ge phosphor. When mounted and evaluated in a VFD or FED in the same manner as in Example 1, green light emission was obtained.
[0027]
【The invention's effect】
According to the phosphor manufacturing method of the present invention, a dope substance compound that contains an element that reacts with H ₂ and is gasified by heating is disposed upstream in a firing furnace in which NH ₃ gas flows. Since the elemental compound is disposed on the downstream side and firing is performed, the following effects are obtained.
[0028]
1. Since the periphery of GaN is covered with a doping material together with ammonia at the time of GaN production, the GaN phosphor can be sufficiently diffused.
[0029]
2. In addition, since GaN is not easily decomposed by being surrounded by S and O during GaN production, the firing temperature can be increased, crystallization of GaN is promoted, and crystallinity with few defects is high. A phosphor is obtained.
[0030]
3. For this reason, a GaN phosphor with high emission intensity can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a tubular furnace used in embodiments and examples of the present invention.
FIG. 2 is a graph showing a relationship between the ZnS scattering amount and the Zn amount in GaN in an example of the present invention.
FIG. 3 is a graph showing a relationship between the amount of Zn in GaN and the relative luminance value of FED / VFD in an example of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Tubular furnace as a baking furnace, 2 ... Heater as a heating means, 3 ... Compound of dope substance, 4 ... Raw material substance of Ga (matrix element compound)

Claims (5)

In the method for producing a GaN phosphor represented by Ga _1-x In _x N: A (0 ≦ x <1, A = Zn, Mg) ,
Inside the firing furnace in which NH ₃ gas is allowed to flow in a predetermined direction, the compound of A that contains a substance arbitrarily selected from S and O as an element that reacts with H ₂ and is gasified by heating is disposed upstream. , characterized in that the firing base element compounds comprising said compounds arranged on the downstream side, while suppressing the reduction action of hydrogen in an atmosphere containing the a was arbitrarily selected material and gasified from S and O A method for producing a GaN phosphor. Asked compound prior to placing on the upstream _{side, ZnS, ZnSO 4, ZnO,} ZnCO 3, MgS, MgSO 4, GaN according to claim 1, wherein a from the group consisting of MgCO ₃ is selected substances A method for producing a phosphor.   2. The method for producing a GaN phosphor according to claim 1, wherein the A contains 0.002 to 1 atm% of Zn. The maternal element compound is heated at relatively high temperatures, The process according to claim 1 GaN phosphor according to previous characterized by heating the hear compounds at relatively low temperatures. In the method for producing a GaN phosphor represented by Ga _1-x In _x N: A, B (0 ≦ x <1, A = Zn, Mg, B = Si, Ge),
Inside the firing furnace in which NH ₃ gas is allowed to flow in a predetermined direction, the compound of A that contains a substance arbitrarily selected from S and O as an element that reacts with H ₂ and is gasified by heating is disposed upstream. The matrix element compound containing the compound and the compound B is disposed on the downstream side, and is fired while suppressing the reduction action by hydrogen in an atmosphere containing a substance arbitrarily selected from S and O and the gasified A. A method for producing a GaN phosphor , characterized in that :

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