JP2002241112A - Method for manufacturing group xiii nitride crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture a group XIII nitride crystal such as gallium nitride having excellent crystallinity under a low dangerous condition particularly by a solution synthesis. SOLUTION: In this method for manufacturing the group XIII nitride crystal, the group XIII nitride crystal having excellent crystallinity is obtained by heating a metal and/or a compound containing a group XIII element and an alkali metal amide of not less the five fold mol thereof under an ammonia atmosphere to bring the molten alkali metal amide into contact with the metal and/or the compound containing the group XIII element.

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 group 13 nitride crystal.

[0002]

2. Description of the Related Art At present, a method for producing a group 13 nitride crystal is disclosed in
Taking aN as an example, a solid phase synthesis method by the reaction of Ga ₂ O ₃ and ammonia gas and a vapor phase growth method such as MOCVD and HVPE are mainstream. However, GaN synthesized by these methods does not necessarily have sufficient properties for practical use. For example, there are problems of low purity, poor crystallinity, and many defects.

[0003] In general, the solution synthesis method is characterized in that high quality crystals are easily obtained as compared with the solid phase synthesis method or the vapor phase growth method. Solution synthesis method of GaN is described in S. Porowski (Reference 1), R. Dw
Reported by ilinski (2).

In the method of Reference 1, a GaN single crystal of 6 to 10 mm is obtained.

[0005] Further, Document 2 reports that a GaN powder crystal having good crystallinity and high luminance was obtained.

Reference 1: Journal of Cryst Growth 178 (19
97) 174-188 "Thermodynamical properties of III-V nit
rides and crystal growth of GaN at high N2 pressur
e "S. Porowski Reference 2: Acta Physica Polonica A 88 (1995) 833-836" Ga
N SYNTHESIS BY AMMONOTHERMAL METHOD "R. Dwilinski

[0007]

[0005] However, Document 1
Is 2000 MPa, and the method of Reference 2 is 100 to 50 MPa.
A high pressure of 0 MPa is required, which is dangerous. Considering industrial production, very expensive equipment is required for high-pressure equipment.

The present invention has been made to solve the above problems, and has as its object to enable the synthesis of a group 13 nitride crystal, particularly the solution synthesis, under a pressure with low risk.

[0009]

Means for Solving the Problems In order to achieve the above object, the present invention can be achieved by the following constitutions (1) to (8) of the present invention. (1) a metal containing at least one group 13 element and / or
Alternatively, a method for producing a group 13 nitride crystal in which a compound and an alkali metal amide are heat-treated in an ammonia atmosphere, wherein the alkali metal amide is a metal containing a group 13 element and / or
Alternatively, a method for producing a Group 13 nitride crystal, which is at least 5 times the mole of a compound and wherein a metal and / or compound containing a Group 13 element is brought into contact with a molten alkali metal amide. (2) a metal containing at least one group 13 element and / or
Alternatively, a method for producing a group 13 nitride crystal in which a compound and an alkali metal amide are heat-treated in an ammonia atmosphere, wherein the alkali metal amide is a metal containing a group 13 element and / or
Alternatively, a method for producing a Group 13 nitride crystal, which comprises dissolving a metal and / or compound containing a Group 13 element in a molten alkali metal amide that is at least 5 times the mole of the compound. (3) The method for producing a Group 13 nitride crystal according to (1) or (2), wherein the compound containing a Group 13 element is an amide or imide compound of a Group 13 element. (4) The method for producing a Group 13 nitride crystal according to (1) or (2), wherein the alkali metal amide is lithium amide, sodium amide, potassium amide, or a mixture thereof. (5) In the method for producing a group 13 nitride crystal according to (1) or (2), the pressure of ammonia is 50 to 0.1 MPa.
a. A method for producing a group 13 nitride crystal, the method comprising: (6) In the method for producing a group 13 nitride crystal according to (1) or (2), an impurity is added to the raw material, and the impurity is selected from the group consisting of elements of group 2 to group 12 and group 14 to group 17. A method for producing a group 13 nitride crystal containing an impurity element, comprising a substance containing at least one element to be performed. (7) In the method for producing a group 13 nitride crystal according to (1) or (2), a seed crystal or a substrate is disposed in the alkali metal amide melt, and the group 13 nitride crystal is placed on the seed crystal or the substrate. A method for producing a group 13 nitride crystal, comprising: (8) In the method for producing a group 13 nitride crystal according to (7), a temperature gradient is provided in the alkali metal amide melt, and the seed crystal or the substrate is located at a low temperature in the molten solution provided with the temperature gradient. A method for producing a group 13 nitride crystal.

That is, in order to solve the above-mentioned problems, a Group 13 nitride crystal of the present invention is obtained by heat-treating a raw material containing at least one kind of Group 13 element and an alkali metal amide in an ammonia atmosphere. Wherein the alkali metal amide is in excess of the group 13 raw material, and the molten alkali metal amide is contacted or dissolved with a raw material containing a group 13 element. In the present invention, the alkali metal amide plays a role of accelerating the generation of the group 13 nitride crystal and dissolving the group 13 raw material. The method disclosed in the above reference 2 is a method for producing a group 13 nitride crystal in a system composed of a raw material containing a group 13 element, an alkali metal amide, and ammonia. It dissolves Group 13 raw materials and alkali metal amides. On the other hand, the present invention is a method characterized in that a molten alkali metal amide is used as a reaction field, and a raw material containing a Group 13 element is contacted or dissolved in the reaction field. The alkali metal amide is added in a large excess in order to increase the contact area between the group 13 raw material and the alkali metal amide melt and to dissolve the group 13 raw material. In the present invention, the ammonia atmosphere is used to prevent the decomposition of the alkali metal amide. If the alkali metal amide is not decomposed, it is not necessary to increase the pressure to supercritical as in the method of Reference 2; The invention is also possible under normal pressure.

Another object of the present invention is to produce a group 13 nitride crystal from a solution. However, the present invention is also applicable to a solid phase reaction in which a raw material containing a group 13 element is simply brought into contact with a metal amide melt. Crystal can be produced.

[0012]

Next, an embodiment of the present invention will be described.

The Group 13 elements include B, Al, Ga, I
n, etc., and the group 13 raw material in the present invention is 1
A compound containing a Group 3 metal and a Group 13 element is used. 1
Examples of the compound containing a Group 3 element include Group 13 amide and Group 13 imide, preferably, aluminum amide, aluminum imide, gallium amide, gallium imide, indium amide, and indium imide. For the purpose of modifying the group 13 nitride crystal and synthesizing a thin film and a bulk single crystal, it is possible to use a group 13 nitride as a raw material, and to use AlN, GaN, InN, and a mixed crystal thereof. Is preferably used.

Further, an impurity may be added to the Group 13 metal amide or imide.
A substance containing at least one element selected from the group consisting of Group 14 and Group 14 to Group 17 elements is used, and a substance containing an alkaline earth metal, a rare earth element, a Group 12 or Group 14 element is preferably used. More preferably, Be, Mg, Ca, Sr, Ba are used as alkaline earth metal elements, and Pr, Nd, Sm, Eu, Dy, Ho, E are used as rare earth elements.
Metals containing elements such as Si, Ge, and Sn as r, Tm, Group 12 elements, Zn, Cd, and Group 14 elements, and compounds such as amides, imides, and nitrides are used.

Specific examples of the alkali metal amide include lithium amide, sodium amide, potassium amide and a mixture thereof. The addition amount is 5
1 to 10,000 times mol, preferably 10 to 1000 times
It is 0 times mol.

As a method of growing a bulk single crystal, it is common practice to add a seed crystal and grow the crystal using the seed crystal as a nucleus. When growing a thin film crystal, a substrate is generally used as a base of the thin film.
In the present invention, a seed crystal or a substrate can be used. Stable as a seed crystal or substrate under reaction conditions,
The crystal structure, the lattice constant, and the coefficient of thermal expansion are preferably made of a material similar to the target group 13 nitride, and more preferably the same material as the target group 13 nitride.
Specific examples include AlN and GaN. Also,
A material obtained by growing a group 13 nitride crystal on a heterogeneous substrate such as sapphire or SiC can also be used. The size of the seed crystal or the substrate can be selected according to the size of the reaction vessel and the desired size of the group 13 nitride crystal.

In the present invention, the reaction temperature must be higher than the melting point of the alkali metal amide,
It is in the range of 0 ° C, preferably 210 ° C to 600 ° C.

The pressure condition is 50 to 0.1MPa.
a, more preferably 20 to 0.1 MPa, more preferably 11.28 to 0.1 MPa.

The reaction time is preferably at least 5 hours, more preferably at least 24 hours.

According to one embodiment of the present invention, a process for producing a group 13 nitride crystal using the apparatus shown in FIG. 1 will be described below.

(First Step) A group 13 raw material, an alkali metal amide and, if necessary, a seed crystal are put in a pressure vessel 1 under a nitrogen atmosphere and sealed. Here, the pressure vessel 1 has heat resistance, pressure resistance, and properties that are stable to Group 13 raw materials, alkali metal amides, and ammonia under the reaction conditions.

(Second Step) Next, liquid ammonia separately held in the pressure vessel 12 is poured into the pressure vessel through the valve 9, or ammonia gas is introduced through the valve 8.

(Third Step) Thereafter, the container is sealed, and then heated to a predetermined temperature by the heater 2. Further, the mixture is stirred by the stirrer 7 if necessary.

(Fourth Step) Next, after holding for a predetermined time, it is cooled to room temperature.

After cooling, the residual gas (ammonia as a specific example) in the container is evacuated, the inside is replaced with nitrogen, and the contents are taken out. Since the Group 13 nitride crystal, which is the object of the present invention, is obtained in a state of being separated into two layers while being submerged in the alkali metal amide, the two can be easily separated and the alkali metal amide can be reused. .

At the stage of separation, the alkali metal amide is attached to the group 13 nitride crystal, so that it is treated with hydrochloric acid to dissolve the alkali metal amide, and then the insoluble matter is filtered off.
After washing with water and drying, a group 13 nitride crystal is obtained.
In the apparatus shown in FIG. 1, ammonia is liquefied in a pipe portion that is not heated. Therefore, in order to obtain a target pressure, an excess amount of ammonia is required from the amount calculated from the internal volume of the pressure vessel 1.

[0027]

[Example 1] 1.65 g of Ga (NH ₂ ) ₃ powder, 12.77 g of LiNH ₂ powder, and 23.82 g of liquid ammonia were placed in a pressure vessel having an inner volume of 283 ml, and the vessel was sealed. As a result of holding at 400 ° C. for 24 hours, the pressure increased to 16.4 MPa.

After the container was cooled to room temperature, the contents were treated with hydrochloric acid, and the insolubles were filtered and washed with water to obtain an off-white powder.
81 g (yield 69%) were obtained. FIG. 2 shows the X-ray diffraction of the obtained powder.

Example 2 16.2 g of Ga (NH ₂ ) ₃ and 23.2 g of LiNH ₂ were placed in a pressure vessel having a volume of 283 ml.
83 g and 16.42 g of liquid ammonia were taken and the container was sealed. As a result of holding at 400 ° C. for 24 hours, the pressure increased to 10.9 MPa.

After cooling to room temperature, the contents are treated with hydrochloric acid,
Further, insoluble matter was filtered and washed with water, and 0.84 g of an off-white powder was obtained.
(72% yield). FIG. 3 shows the X-ray diffraction of the obtained powder.
Shown in

Example 3 1100 Zn (NH ₂ ) ₂
1.65 g of Ga (NH ₂ ) ₃ added with ppm
The H ₂ 23.92g, and liquid ammonia 23.82
g was placed in a pressure vessel having an internal volume of 283 ml and sealed. 4
As a result of holding at 00 ° C. for 24 hours, the pressure was 17.3 MPa.
Up.

After cooling to room temperature, the contents are treated with hydrochloric acid,
The insoluble matter was filtered and washed with water to obtain 0.98 g (85% yield) of off-white powder. FIG. 4 shows the X-ray diffraction of the obtained powder.

Example 4 2.5 × 1.5 × 0.2 mm at a position 20 mm from the bottom of a pressure vessel having an inner volume of 283 ml
Was fixed with a wire. Ga (NH)
₂ ) 0.83 g of ₃ , 73.62 g of LiNH ₂ and 16.34 g of liquid ammonia were taken and sealed. 400
As a result of holding at 24 ° C. for 24 hours, the pressure increased to 9.8 MPa.

After cooling to room temperature, the seed crystal was taken out and washed with water. Hexagonal crystals were growing like islands on the surface of the seed crystal. An optical microscope image of the grown crystal is shown in FIG.

Example 5 Mg (NH 2) 2 was added to 1400
1.67 g of Ga (NH2) 3 added with ppm, LiN
24.11 g of H2 and 23.9 of liquid ammonia
3 g of the solution is placed in a pressure vessel having a volume of 283 ml, sealed, and kept at 400 ° C. for 24 hours.

After cooling to room temperature, the contents are treated with hydrochloric acid,
Further, the insoluble matter was filtered and washed with water.
An aN crystal can be obtained.

Example 6 1.05 g of Al (NH2) 3 powder, 24.11 g of LiNH2 powder and 23.93 g of liquid ammonia were placed in a pressure vessel having an inner volume of 283 ml.
Then, the container is sealed and kept at 400 ° C. for 32 hours.

After cooling the container to room temperature, the contents are treated with hydrochloric acid, and the insolubles are filtered and washed with water to obtain AlN crystals.

[0039]

According to the method for producing a group 13 nitride crystal of the present invention, it is possible to produce a nitride crystal from a solution under a less dangerous pressure condition. Therefore, a group 13 nitride crystal having good crystallinity can be manufactured safely and inexpensively.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an apparatus for producing a group 13 nitride crystal according to an embodiment of the present invention.

FIG. 2 is a powder X-ray diffraction diagram of the GaN crystal obtained in Example 1.

FIG. 3 is a powder X-ray diffraction diagram of the GaN crystal obtained in Example 2.

FIG. 4 is a powder X-ray diffraction diagram of the GaN crystal obtained in Example 3.

FIG. 5 is an optical microscope image of a GaN crystal grown on a seed crystal in Example 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hastelloy pressure vessel 2 ... Heater 3 ... Cover 4 ... Packing 5 ... Tightening bottle 6 ... Thermocouple 7 ... Stirrer 8 ... Valve 9 ...・ Valve 10 ・ ・ ・ Safety valve 11 ・ ・ ・ Pressure gauge 12 ・ ・ ・ Glass pressure vessel

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G077 AA02 AA03 BE11 BE13 BE15 CD05 EA03 MB12 MB35 QA04 QA12 QA34

Claims (8)

[Claims] 1. A method for producing a Group 13 nitride crystal, wherein a metal and / or compound containing at least one Group 13 element and an alkali metal amide are heat-treated in an ammonia atmosphere. A method for producing a Group 13 nitride crystal, which comprises contacting a metal and / or compound containing a Group 13 element with a molten alkali metal amide at least 5 times the mole of a metal and / or compound containing an element. 2. A method for producing a Group 13 nitride crystal, comprising subjecting a metal and / or compound containing at least one Group 13 element and an alkali metal amide to heat treatment in an ammonia atmosphere, wherein the alkali metal amide is a Group 13 element. A method for producing a Group 13 nitride crystal, which is at least 5 times the mole of a metal and / or compound containing an element, and wherein the metal and / or compound containing a Group 13 element is dissolved in a molten alkali metal amide. 3. The method for producing a Group 13 nitride crystal according to claim 1, wherein said compound containing a Group 13 element is an amide or imide compound of a Group 13 element. 4. The method according to claim 1, wherein said alkali metal amide is lithium amide, sodium amide, potassium amide or a mixture thereof.
A method for producing a group III nitride crystal. 5. The method for producing a group 13 nitride crystal according to claim 1, wherein the pressure of ammonia is 50 to 0.1.
A method for producing a group 13 nitride crystal, wherein the pressure is MPa. 6. The method for producing a group 13 nitride crystal according to claim 1, wherein an impurity is added to the raw material, and the impurity is selected from the group consisting of elements from group 2 to group 12 and group 14 to group 17. A method for producing a group 13 nitride crystal containing an impurity element, comprising a substance containing at least one element to be performed. 7. The method for producing a group 13 nitride crystal according to claim 1, wherein a seed crystal or a substrate is disposed in the alkali metal amide melt, and the group 13 nitride crystal is placed on the seed crystal or the substrate. A method for producing a group 13 nitride crystal, comprising: 8. The method for producing a group 13 nitride crystal according to claim 7, wherein a temperature gradient is provided in the alkali metal amide melt, and the seed crystal or the substrate has a low temperature in the molten solution provided with the temperature gradient. A method for producing a Group 13 nitride crystal, comprising: