JP2002326898A - Method of crystal growth of group iii nitride and equipment for crystal growth of group iii nitride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of crystal growth of group III nitride and equipment for crystal growth of group III nitride capable of crystal growing a group III nitride having a preferable size for practically manufacturing a device such as a light emitting diode of high performance, or an LD, with low cost and high performance. SOLUTION: A mixed molten liquid vessel 102 is filled with a mixed melt 103 which is composed of Ga as group III metal, and Na as alkali metal, wherein, pulity of Na is 99%, purity of Ga is 99.9999%, and purity of nitrogen gas is 99.999%, in the case of the material of vessel for mixed melt is sintered BN, solid matter 110 is formed in a shape having holes 111. Through the holes 111 the nitrogen gas is dissolved into the mixed melt 103, thereby the single crystal of GaN 109 as a group III nitride can be grown in the mixed melt 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blue-violet light source for an optical disk, an ultraviolet light source (LD or LED), a blue-violet light source for electrophotography, a group III nitride electronic device, a group III nitride usable for LED lighting equipment, and the like. The present invention relates to a nitride crystal growth method and a group III nitride crystal growth apparatus.

[0002]

2. Description of the Related Art InGaAlN-based (group III nitride) devices currently used as violet-blue-green light sources are:
Most of them are on a sapphire or SiC substrate.
It is manufactured by crystal growth using O-CVD (metal organic chemical vapor deposition), MBE (molecular beam crystal growth), or the like. When sapphire or SiC is used as a substrate, crystal defects due to a large difference in thermal expansion coefficient and lattice constant from group III nitrides increase. For this,
There are problems that the device characteristics are poor, for example, it is difficult to extend the life of the light emitting device, and the operating power is increased.

Further, in the case of a sapphire substrate, since it is insulative, it is impossible to take out an electrode from the substrate side as in a conventional light emitting device. They need to be removed. As a result, there is a problem in that the device area increases and the cost increases. It was also fabricated on a sapphire substrate
In the group III nitride semiconductor device, it is difficult to separate a chip by cleavage, and it is not easy to obtain a cavity facet required for a laser diode (LD) by cleavage. For this reason, at present, cavity end face formation by dry etching,
Alternatively, after the sapphire substrate is polished to a thickness of 100 μm or less, the resonator end face is formed in a form close to cleavage. In this case as well, the resonator end face such as a conventional LD is separated from the chip by a single process. It is not possible to easily perform the process, which leads to an increase in the complexity of the process and an increase in cost.

In order to solve these problems, it has been proposed to reduce the crystal defects by selectively growing a group III nitride semiconductor film on a sapphire substrate in a lateral direction or by taking other measures.

[0005] For example, the document "Japanese Journal of Applie"
d Physics Vol.36 (1997) Part 2, No.12A, L1568-157
"1" (hereinafter referred to as a first conventional technique) shows a laser diode (LD) as shown in FIG. In the laser diode of FIG. 10, a GaN low-temperature buffer layer 2 and a GaN layer 3 are sequentially grown on a sapphire substrate 1 by an MO-VPE (metal organic chemical vapor deposition) apparatus, and then a SiO ₂ mask 4 for selective growth is formed. I do. This SiO ₂ mask 4
Is formed through a photolithography and etching process after depositing a SiO ₂ film with another CVD (chemical vapor deposition) apparatus. Next, a GaN film 3 ′ having a thickness of 20 μm is grown on the SiO ₂ mask 4 again by the MO-VPE apparatus, whereby GaN is selectively grown in the lateral direction.
Crystal defects are reduced as compared with the case where selective lateral growth is not performed. Further, by introducing a modulation-doped strained superlattice layer (MD-SLS) 5 formed thereon, it is possible to prevent crystal defects from extending to the active layer 6. As a result, the device lifetime can be extended as compared with the case where the selective lateral growth and the modulation-doped strained superlattice layer are not used.

In the case of the first prior art, it is possible to reduce crystal defects as compared with a case where a GaN film is not selectively grown in a lateral direction on a sapphire substrate. The aforementioned problems with insulation and cleavage remain. Further, the crystal growth by the MO-VPE apparatus is required twice with the SiO ₂ mask forming step interposed therebetween, which causes a new problem that the process becomes complicated.

As another method, for example, the document “Appl
ied Physics Letters, Vol. 73, No. 6, p. 832-834 (199
8) "(hereinafter referred to as a second prior art) proposes applying a GaN thick film substrate. In the second prior art, after the selective lateral growth of 20 μm in the above first prior art, a 200 μm thick GaN film is grown by an H-VPE (hydride vapor phase epitaxy) apparatus. By polishing the GaN film grown as a thick film from the sapphire substrate side to a thickness of 150 μm,
Make a substrate. On this GaN substrate, MO-VPE equipment is used to sequentially grow crystals necessary for an LD device, and by manufacturing an LD device, it is possible to reduce crystal defects and use a sapphire substrate. It is possible to solve the above-mentioned problems relating to the insulating property and the cleavage by the method. Japanese Patent Application Laid-Open No. 11-4048 has been proposed as a device similar to the second prior art, and FIG. 11 shows a semiconductor laser disclosed in Japanese Patent Application Laid-Open No. 11-4048.

However, the second prior art has a more complicated process than the first prior art, resulting in a further increase in cost. Further, when a GaN thick film having a thickness of about 200 μm is grown by the method of the second prior art, stress due to a difference in lattice constant and a difference in thermal expansion coefficient from sapphire as a substrate increases, and the A new problem that warpage and cracks occur.

To avoid this problem, Japanese Patent Application Laid-Open No.
No. 256662 proposes that the thickness of a substrate (sapphire and spinel) from which a thick film is to be grown be 1 mm or more. Thus, by using a substrate having a thickness of 1 mm or more, even if a GaN film having a thickness of 200 μm is grown, the substrate is prevented from warping or cracking. However, such a thick substrate requires a high cost of the substrate itself and requires much time for polishing, leading to an increase in the cost of the polishing process. That is, when a thick substrate is used, the cost is higher than when a thin substrate is used. When a thick substrate is used, the substrate does not warp or crack after growing a thick GaN film, but stress is relaxed in the polishing step, and warpage or cracks occur during polishing. For this reason, even if a thick substrate is used, a GaN substrate with high crystal quality cannot be easily manufactured with a large area.

On the other hand, the literature "Journal of Crystal Growth,
Vol.189 / 190, pp.153-158 (1998) ”(hereinafter referred to as a third conventional technique) proposes growing a GaN bulk crystal and using it as a homoepitaxial substrate. This third prior art is 1400-1700.
In this method, GaN is crystal-grown from liquid Ga at a high temperature of ° C. and an extremely high nitrogen pressure of several tens of kbar. In this case, a group III nitride semiconductor film required for a device can be grown using the bulk-grown GaN substrate. Therefore, a GaN substrate can be provided without complicating the process unlike the first and second prior arts.

However, the third prior art has a problem in that crystal growth at a high temperature and a high pressure is required, and a reaction vessel capable of withstanding the growth is extremely expensive. In addition, even with such a growth method, the size of the obtained crystal is at most about 1 cm, which is too small for practical use of the device.

As a method for solving the problem of the GaN crystal growth at a high temperature and a high pressure, the literature "Chemistry of Mater
ials Vol. 9 (1997) p. 413-416 ”(hereinafter referred to as“ fourth prior art ”) includes GaN using Na as a flux.
Crystal growth methods have been proposed. In this method, sodium azide (NaN ₃ ) and metal Ga are used as raw materials, and the reaction vessel is sealed in a stainless steel reaction vessel (container inner dimensions; inner diameter = 7.5 mm, length = 100 mm) in a nitrogen atmosphere, and the reaction vessel is placed in a reactor. The GaN crystal is grown by maintaining the temperature at ８００800 ° C. for 24 to 100 hours. In the case of the fourth prior art, crystal growth can be performed at a relatively low temperature of about 600 to 800 ° C., and the pressure in the vessel is at most 1
A feature is that the pressure can be reduced to about 00 kg / cm ² as compared with the third conventional technique. However, a problem with the fourth prior art is that the size of the obtained crystal is 1 mm.
It is a point small enough to be less than. Such a size is too small to make the device practical, as in the third prior art.

Further, Japanese Patent Application Laid-Open No. 2000-327495 (hereinafter referred to as a fifth conventional technique) proposes a technique in which the above-described fourth conventional technique is combined with an epitaxial method using a substrate. In the fifth prior art, a substrate in which GaN or AlN is previously grown on a substrate surface is used as a substrate, and a GaN film is epitaxially grown thereon using the fourth prior art. However, the fifth prior art is basically epitaxial growth, and does not solve the problem of crystal defects as in the first and second prior arts. Further, since a GaN film or an AlN film is grown on the substrate in advance, the process becomes complicated, leading to a high cost.

Recently, Japanese Patent Application Laid-Open Nos. 2000-12900 and 2000-22212 (hereinafter, referred to as a sixth prior art) propose a method of manufacturing a GaN thick film substrate using a GaAs substrate. I have. 12 and 13 show a method of manufacturing the GaN thick film substrate according to the sixth conventional technique. First, referring to FIG. 12, (11
1) Si on the GaAs substrate 60 as in the first prior art.
Using the O ₂ film or SiN film as a mask 61, a GaN film 63 is selectively grown to a thickness of 70 μm to 1 mm (FIG. 12A).
~ (3)). This crystal growth is performed by H-VPE. Thereafter, the GaAs substrate 60 is etched and removed with aqua regia to produce a GaN free-standing substrate 63 (FIG. 12 (4)).
Based on the GaN free-standing substrate 63, a GaN crystal 64 having a thickness of several tens of millimeters is grown again by H-VPE (FIG. 13A). This GaN with a thickness of several tens mm
The crystal 64 is cut into a wafer by a slicer and Ga
An N wafer is manufactured (FIGS. 13 (2) and (3)).

According to the sixth prior art, a GaN free-standing substrate 63 is obtained, and a GaN crystal 64 having a thickness of several tens mm is further provided.
Can be obtained. However, the sixth related art has the following problems. That is, SiN film or SiN film
Since the O ₂ film is used as a mask for selective growth, the manufacturing process is complicated, leading to an increase in cost. Also, HV
When a GaN crystal having a thickness of several tens of mm is grown by PE, a GaN crystal (single crystal or polycrystal) and an amorphous GaN having the same thickness adhere to the inside of the reaction vessel. There's a problem. Further, since the GaAs substrate is etched and removed each time of growth as a sacrificial substrate,
This leads to higher costs. Also, regarding the crystal quality, it basically comes from crystal growth on a heterogeneous substrate called GaAs.
There remains a problem that the defect density is high due to lattice irregularities and differences in thermal expansion coefficients.

[0016]

SUMMARY OF THE INVENTION The present invention does not complicate the steps which are the problems of the first, second, fifth or sixth prior art, and has the problem of the third prior art. A high-performance device such as a light-emitting diode or an LD is manufactured without using an expensive reaction vessel and without reducing the size of a crystal which is a problem of the third and fourth prior arts. To provide a group III nitride crystal growth method and a group III nitride crystal growth apparatus capable of growing a low cost, high quality group III nitride crystal with a practical size. And

[0017]

In order to achieve the above object, according to the present invention, a mixed melt of an alkali metal and a substance containing at least a group III metal is formed in a predetermined container, A group III nitride crystal growth method for growing a group III nitride composed of a group III metal and nitrogen from the mixed melt and a substance containing at least nitrogen, wherein the surface of the mixed melt is mixed. The method is characterized in that a group III nitride is grown in a state in which nitrogen can be introduced.

According to a second aspect of the present invention, there is provided the method of growing a group III nitride crystal according to the first aspect, wherein the purity of the alkali metal and / or the purity of the substance containing the group III metal is improved. The purity of the substance containing nitrogen is such that at least a part of the surface of the mixed melt is polycrystalline or non-quality.
It is characterized in that it has a purity required to be not covered with the group III nitride.

According to a third aspect of the present invention, in the method of growing a group III nitride crystal according to the first or second aspect, Na is used as the alkali metal.

According to a fourth aspect of the present invention, in the method of growing a group III nitride crystal according to the first or second aspect, Ga is used as the group III metal.

According to a fifth aspect of the present invention, in the method of growing a group III nitride crystal according to the first or second aspect, nitrogen gas, ammonia gas or sodium azide is used as the substance containing at least nitrogen. It is characterized by being able to.

According to a sixth aspect of the present invention, in the method of growing a group III nitride crystal according to the first or second aspect, the predetermined container is formed of BN.

According to a seventh aspect of the present invention, in the method of growing a group III nitride crystal according to the first or second aspect, the predetermined container is formed of AlN.

According to an eighth aspect of the present invention, in the method of growing a group III nitride crystal according to the first or second aspect, the predetermined container is formed of pyrolytic BN. .

Further, the invention according to claim 9 provides a mixed melt holding container for holding a mixed melt of an alkali metal and a substance containing at least a group III metal, and a reaction container provided with the mixed melt holding container. At least nitrogen introducing means for introducing at least a nitrogen-containing substance into the reaction vessel, and a region where the mixed melt is in contact with the mixed melt holding vessel has sufficient purity with a small amount of impurities. It is characterized by doing.

The invention according to claim 10 is the invention according to claim 9
In the above-described group III nitride crystal growth apparatus, the mixed melt holding container is formed of pyrolytic BN.

The invention according to claim 11 is the same as the claim 9.
In the III-nitride crystal growing apparatus according to the above, the same type of III-nitride as the III-nitride crystal grown by the III-nitride crystal growing apparatus is applied in advance to the inside of the mixed melt holding vessel. It is characterized by having.

The invention according to claim 12 provides a reaction vessel for holding a mixed melt of an alkali metal and a substance containing at least a group III metal, and a method for introducing a substance containing at least nitrogen into the reaction vessel. At least nitrogen introducing means, the reaction vessel is configured by a vessel outer wall, and a vessel inner wall for substantially holding the mixed melt,
A region where the mixed melt contacts the inner wall of the container is characterized in that it has a sufficient purity with a small amount of impurities.

[0029] Further, the invention according to claim 13 is based on claim 1.
3. The group III nitride crystal growing apparatus according to item 2, wherein the outer wall of the container is formed of stainless steel.

The invention according to claim 14 is the first invention.
3. The group III nitride crystal growth apparatus according to item 2, wherein the inner wall of the container is formed of pyrolytic BN.

The invention according to claim 15 is the first invention.
3. The group III nitride crystal growth apparatus according to item 2, wherein the same type of group III nitride as the group III nitride to be crystal-grown by the group III nitride crystal growth apparatus is applied in advance to the inner wall of the container. It is characterized by.

The invention according to claim 16 is the invention according to claim 9
Alternatively, in the group III nitride crystal growth apparatus according to claim 12, Na is used as the alkali metal.

The invention according to claim 17 is based on claim 9.
Alternatively, in the apparatus for growing a group III nitride crystal according to claim 12, Ga is used for the group III metal.

The invention according to claim 18 is the invention according to claim 9
Alternatively, in the group III nitride crystal growing apparatus according to the twelfth aspect, the substance containing at least nitrogen is nitrogen gas, ammonia gas or sodium azide.

[0035]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a group III nitride crystal growth apparatus according to the present invention.

Referring to FIG. 1, a mixed melt holding vessel 102 for holding a mixed melt of an alkali metal (for example, Na) and a substance containing at least a Group III metal (for example, Ga) is provided in a reaction vessel 101. Is installed.

The substance containing the alkali metal and at least the group III metal may be supplied from the outside or may be present in the reaction vessel 101 from the beginning.

The reaction vessel 101 is made of, for example, stainless steel.

The reaction vessel 101 includes the reaction vessel 10
A nitrogen supply pipe 104 for supplying a substance containing at least nitrogen (for example, nitrogen gas, ammonia gas, or sodium azide) to the space 108 in 1 is provided. Note that the term nitrogen as used herein refers to a nitrogen molecule or an atomic nitrogen generated from a nitrogen molecule or a compound containing nitrogen, and an atomic group and a molecular group containing nitrogen. Let's say something like

The nitrogen supply pipe 104 is provided with a pressure adjusting mechanism 105 for adjusting the pressure of the nitrogen gas. The pressure adjusting mechanism 105 includes a pressure sensor, a pressure adjusting valve, and the like.

The reaction vessel 101 is set to a temperature at which a group III nitride (for example, GaN) can be crystal-grown.
A heating device 106 for controlling the inside of the device 1 is provided. That is, by the temperature control function of the heating device 106, the temperature inside the reaction vessel 101 can be raised to a temperature at which crystal growth can be performed, and the temperature can be lowered to a temperature at which crystal growth stops, and the temperature can be maintained at those temperatures for an arbitrary time. It is possible.

In the apparatus for growing a group III nitride crystal of FIG. 1, the temperature and the effective nitrogen partial pressure in the reaction vessel 101 are set to the conditions under which the group III nitride crystal grows.
The crystal growth of the group nitride can be started.

Such a group III nitride crystal growing apparatus,
In the group III nitride crystal growth method, a mixed melt of an alkali metal and a substance containing at least a group III metal is formed in a predetermined vessel, and the mixed melt and a substance containing at least nitrogen are mixed with a group III metal. Since a group III nitride composed of nitrogen and nitrogen is grown, low-cost, high-quality group III nitride crystals do not require complicated steps as in the first or second prior art. Can be obtained.

Further, the growth temperature is as low as 1000 ° C. or less,
Since the group III nitride crystal can be grown under the condition that the pressure is as low as about 100 atm or less, it is not necessary to use an expensive reaction vessel that can withstand an ultra-high pressure and an ultra-high temperature unlike the third related art. . As a result, it becomes possible to produce a group III nitride crystal at low cost.

In a group III nitride crystal growing apparatus as shown in FIG. 1, when a substance containing an alkali metal, a substance containing a group III metal, a substance containing nitrogen, or a mixed container containing a large amount of impurities contains a large amount of impurities. In the case, the solids cover the surface of a mixed melt composed of an alkali metal and a substance containing at least a Group III metal, because the impurities serve as nuclei or cause a catalytic action. If the surface of the mixed melt is covered with this solid, the subsequent dissolution of nitrogen into the mixed melt is inhibited, and the crystal growth of the group III nitride crystal does not proceed.

The inventor of the present application has found that the cause of generation of a solid material covering the surface of the mixed melt is mainly a group III nitride (the solid material is a polycrystalline or non-quality group III nitride), The impurities contained in the alkali metal, and / or the impurities contained in the substance containing at least the group III metal, and / or the impurities contained in the substance containing nitrogen, and / or the predetermined container containing the mixed melt. It has been found that it is caused by impurities (impurities coming out of the surface of the predetermined container or the inside of the predetermined container).

The present invention has been made based on the above findings by the inventor of the present application.
When a mixed melt of an alkali metal and a substance containing at least a group III metal is formed, and a group III nitride composed of a group III metal and nitrogen is crystal-grown from the mixed melt and a substance containing at least nitrogen. Further, the present invention is characterized in that a group III nitride is grown while the surface of the mixed melt is in a state where nitrogen can be introduced into the mixed melt.

More specifically, the present invention relates to an impurity contained in an alkali metal and / or an impurity contained in a substance containing at least a group III metal and / or an impurity contained in a substance containing nitrogen and / or To prevent the entire surface of the mixed melt from being covered by a solid based on impurities in a predetermined container containing the mixed melt (impurities coming out of the surface of the predetermined container or the inside of the predetermined container). Is intended.

For this reason, in the present invention, the purity of the alkali metal and / or the purity of the substance containing the group III metal and / or the purity of the substance containing nitrogen is adjusted at least partially on the surface of the mixed melt. It is of the purity necessary to be uncovered by polycrystalline or non-quality Group III nitrides.

Specifically, as a result of an experiment conducted by the inventor of the present application, it was found that when the purity of the alkali metal was less than 99%, the surface of the mixed melt was covered with a solid. On the other hand, when the purity of the alkali metal is 99% or more, the surface of the mixed melt is less likely to be covered with the solid.

Further, as a result of an experiment by the inventor of the present application,
It was found that when the purity of the alkali metal was 99.9% or more, the surface of the mixed melt was hardly covered by the solid matter.

Further, the purity of the alkali metal is 99.95.
%, It was found that the solid material hardly covered the surface of the mixed melt. Note that 99.95% is the highest purity among the currently available high-purity alkali metals that are generally available.

It is also preferable to increase the purity of the substance containing the group III metal and the purity of the substance containing nitrogen.

Further, it is preferable to use a predetermined container containing a small amount of impurities for the predetermined container for storing the mixed melt.

For example, the predetermined container can be formed of BN.

Alternatively, the predetermined container can be formed of AlN.

Alternatively, the predetermined container can be formed of pyrolytic BN.

Here, the material of the predetermined container is Al
BN is preferable because it has less impurities than N. Further, pyrolytic BN is more preferable because it has less impurities than AlN and BN.

Note that the pyrolytic BN is a PBN.
(Pyrolytic BoronNitride) and
It is usually said that CV of boron chloride and ammonia
D (Chemical Vapor Depositi
on)). Commonly spread
BN manufactured by hot sintering
With less impurities and higher purity. That is,
B for sintered body BN _TwoO_Three, CaO, SiO_TwoIncludes several%
It is generally rare, but pyrolytic BN
Has a low content of these impurities.

According to an experiment conducted by the inventor of the present application, when a BN of a sintered body is used as a material of a predetermined container, even when the pyrolytic BN is used under the same conditions as those in which the solid material covers the surface of the mixed melt. It was found that the surface of the mixed melt was prevented from being covered with the solid.

As described above, according to the present invention, the impurities contained in the alkali metal and / or the impurities contained in the substance containing at least the group III metal and / or the impurities contained in the substance containing nitrogen and / or By reducing impurities (impurities coming out of the surface of the predetermined container or the inside of the predetermined container) of the predetermined container containing the mixed melt, the entire surface of the mixed melt is not covered with the solid material. Thereby, the continuous dissolution of nitrogen into the mixed melt proceeds, and the crystal growth of the group III nitride crystal can be continued. Furthermore, since the amount of the group III metal constituting the solid is reduced, the consumption of the group III metal on the surface of the mixed melt can be reduced, and the group III metal in the group III nitride crystal in the mixed melt contains a large amount of the group III metal. It becomes possible to supply. As a result, it is possible to grow a large group III nitride crystal of a desired size.

First Embodiment In a first embodiment, as shown in FIG. 2, a mixed melt holding vessel 102 contains a mixed melt composed of Ga as a group III metal and Na as an alkali metal. The liquid 103 is stored.

In the first embodiment (the example of FIG. 2), Ga as a group III metal has a purity of 99.9999%, and Na as an alkali metal has a purity of 99%.

In the first embodiment (example of FIG. 2),
The purity of the nitrogen gas supplied from the nitrogen supply pipe 104 is 9
9.999%.

The material of the mixed melt holding container 102 is
The sintered body is BN (nitrogen boron).

When a group III nitride crystal is grown by a group III nitride crystal growth apparatus having the structure shown in FIG. 1, in the first embodiment, the pressure of nitrogen gas in the reaction vessel 101 is set to 50 atm. By raising the temperature in the reaction vessel 101 to 750 ° C., at which crystal growth starts, and maintaining this growth condition for a certain period of time, the GaN crystal 109, which is a group III nitride, is mixed as shown in FIG. It grows in the melt holding container 102. At this time, the surface of the mixed melt 103 is
10, a hole 111 is formed in each part of the solid material 110, and the solid material 110 is mixed with the mixed melt 103.
It does not cover the whole area of. Thereby, nitrogen can be dissolved into the mixed melt 103 through the holes 111. As described above, the degree to which the solid object 110 covers,
Experiments by the inventor of the present application have found that it depends on the purity of Na, the purity of Ga, the purity of nitrogen gas, or the material of the mixed melt holding vessel 102. Among them, it was found that the extent to which the solid substance 110 was covered was most affected by the purity of Na. As a result of the analysis, the solid substance 1 covering the surface of the mixed melt 103
10 was found to be mainly composed of polycrystalline GaN or non-quality GaN.

As in the above example, the purity of Na is 99%,
The purity of Ga is 99.9999% and the purity of nitrogen gas is 9
In the case where the material of the mixed melt holding container 102 is 9.999%, and the material of the mixed melt holding container 102 is BN of a sintered body, as shown in FIG. That hole 11
The nitrogen melts into the mixed melt 103 through 1 to form GaN as a group III nitride in the mixed melt 103.
Single crystal 109 can be grown.

Second Embodiment As in the first embodiment, the second embodiment uses the same group III nitride crystal growth apparatus as in FIG. 1 and uses the same method as in the first embodiment to grow a crystal. I try to make it.

Here, the purity of Ga as a group III metal is 99.9999%, and the purity of nitrogen gas is 99.9999%.
99%, and the material of the mixed melt holding container 102 is BN of a sintered body. The growth conditions such as temperature and pressure are the same as in the first embodiment.

The difference from the first embodiment is that Na as an alkali metal has a purity of 99% in the first embodiment, whereas Na has a purity of 99% in the second embodiment. Is 99.9%. In this case, the state inside the mixed melt holding container 102 is shown in FIG.
become that way.

That is, in the second embodiment, the first
The nitrogen gas pressure and temperature are set in the same manner as in the first embodiment, and the growth conditions are kept constant.
GaN single crystal 109, which is a group nitride, grows,
At this time, in the second embodiment, the surface of the mixed melt 103 in the mixed melt holding container 102 was covered with about half of the mixed melt 103 by the solid substance 110. The ratio of the solid material 110 covering the surface of the mixed melt 103 may be about half, or may be larger or smaller than that, depending on the growth lot, but at least in the first embodiment. It is not like a hole.

The surface of this mixed melt 103 is solid 110
Through the region 111 that is not covered by nitrogen.
3, and the crystal growth of the GaN crystal 109 proceeds. In the second embodiment, the mixed melt 1
The area 111 where the solid object 110 does not cover the surface of
By increasing the number as compared with the embodiment, it is possible to grow a larger GaN single crystal 109. That is,
Since the generation of the solid material 110 mainly composed of polycrystalline GaN or non-quality GaN is small, the mixed melt 1
03 is more efficiently used for the desired GaN single crystal 109.
It is possible to contribute to the growth of. Further, since the dissolution rate of nitrogen is high, generation of many nuclei is prevented, nitrogen is preferentially taken into large nuclei, and large GaN single crystals can be grown.

As described above, in the second embodiment, Na
Is increased to 99.9%, which is higher than that in the first embodiment, the amount of the solid substance 110 covering the surface of the mixed melt 103 is reduced, and a larger GaN single crystal 109 can be grown. Become.

Third Embodiment As in the first and second embodiments, the third embodiment is similar to FIG.
Using the same group III nitride crystal growth apparatus as
The crystal is grown in the same manner as in the embodiment.

Here, the purity of Ga as a group III metal is 99.9999%, and the purity of nitrogen gas is 99.9999%.
99%, and the material of the mixed melt holding container 102 is BN of a sintered body. The growth conditions such as temperature and pressure are the same as in the first and second embodiments.

The difference from the first and second embodiments is that
In the third embodiment, the purity of Na as an alkali metal is set to 99.95% or more. In this case, the state inside the mixed melt holding container 102 is as shown in FIG.

That is, in the third embodiment, as in the first and second embodiments, the nitrogen gas pressure and the temperature are set and the growth conditions are kept constant.
A GaN single crystal 109, which is a group III nitride, grows therein. At this time, in the third embodiment, the solid substance 110 is a part of the surface of the mixed melt 103 in the mixed melt holding vessel 102. Only scattered around. The ratio of the solid material 110 covering the mixed melt 103 is at most about 10%. This is substantially opposite to the ratio of the region covered by the solid object 110 and the region 111 not covered (perforated region) 111 in the first embodiment.

Nitrogen flows through the region 111 where the surface of the mixed melt 103 is not covered with the solid substance 110.
The GaN crystal 109 melts into the GaN crystal 109 and advances the crystal growth. In the third embodiment, the mixed melt 10
Since the number of regions 111 where the surface of 3 is not covered by the solid substance 110 is larger than in the first and second embodiments, a larger GaN single crystal 109 can be grown. That is, since the generation of the solid substance 110 mainly composed of polycrystalline GaN or non-quality GaN is small, Ga in the mixed melt 103 can be more efficiently converted to the desired G.
It is possible to contribute to the growth of the aN single crystal 109.
Further, since the dissolution rate of nitrogen is high, generation of many nuclei is prevented, nitrogen is preferentially taken into large nuclei, and large GaN single crystals can be grown.

As described above, in the third embodiment, Na
Is increased to 99.95%, which is higher than that in the first and second embodiments, so that the solid material 110 covering the surface of the mixed melt 103 becomes small, and a larger GaN single crystal 109 is grown. It is possible to do.

Fourth Embodiment As in the first to third embodiments, the fourth embodiment uses the same III-nitride crystal growth apparatus as in FIG. 1 and uses the same as the first to third embodiments. The crystal is grown by the same method.

Here, the purity of Ga as a group III metal is 99.9999%, and the purity of nitrogen gas is 99.9999%.
99%. The growth conditions such as temperature and pressure are first to third.
This is the same as the embodiment.

The fourth embodiment differs from the first to third embodiments in that the purity of Na as an alkali metal is set to 99.95% or more in the fourth embodiment. The material is pyrolytic BN. In this case, the mixed melt holding container 102
The state inside is as shown in FIG.

That is, also in the fourth embodiment, the first
By setting the nitrogen gas pressure and temperature and keeping the growth conditions constant in the same manner as in the third to third embodiments, the mixed melt 103
A GaN single crystal 109, which is a group III nitride, grows therein. At this time, in the fourth embodiment, the surface of the mixed melt 103 in the mixed melt holding vessel 102 has first and second crystals. 2, the solid substance 11 present in the third embodiment
0 does not exist. That is, in the case of the fourth embodiment, there is no solid substance 110 that blocks the dissolution of nitrogen into the mixed melt 103. Therefore, the crystal growth of the GaN crystal 109 can proceed more smoothly.

As described above, in the fourth embodiment, since there is no solid object 110, the larger GaN single crystal 10
9 can be grown. That is, polycrystalline G
Since there is no generation of the solid material 110 in which aN or non-quality GaN is a main constituent material, G in the mixed melt 103 is reduced.
a can more efficiently contribute to the growth of the desired GaN single crystal 109. Further, since the rate of nitrogen dissolution is high, generation of a large number of nuclei is prevented, nitrogen is preferentially taken into large nuclei, and a large GaN single crystal can be grown.

As described above, in the fourth embodiment, Na
Of the mixed melt 103 by increasing the purity of the mixed melt 103 to 99.95% or more as compared with the first, second, and third embodiments, and by setting the material of the mixed melt holding container 402 to pyrolytic BN. The solid object 110 covering the surface of the GaN single crystal is eliminated, and a larger GaN single crystal 109 can be grown. Also, using pyrolytic BN, Na
Since the purity is high, impurities contained in the mixed melt 103 are reduced, and the crystal quality of the obtained GaN single crystal 109 is also improved.

In the above example, the alkali metal is used.
Na is used, but K (potassium) is used in addition to Na
It is also possible to use an alkali metal such as Also on
In the example described above, as a substance containing at least a Group III metal,
Although Ga is used, a GaNa alloy or Al or
It is also possible to use other Group III metals such as In
You. In the above example, the substance containing at least nitrogen
And nitrogen gas (N_Two) But other than nitrogen gas
Also, ammonia gas and sodium azide (NaN _Three)
Etc. can also be used.

Further, the mixed melt holding container 102 includes
Although the BN material is used in the second and third embodiments, for example, AlN can be used instead of BN. However, as a material of the mixed melt holding container 102, BN is better than AlN. As a material of the mixed melt holding container 102, pyrolytic BN is better than BN as in the fourth embodiment.

In other words, the apparatus for growing a group III nitride crystal of the present invention comprises a mixed melt holding vessel 102 for holding a mixed melt of an alkali metal and a substance containing at least a group III metal.
And the reaction vessel 10 in which the mixed melt holding vessel 102 is installed.
1 and nitrogen introducing means (104, 105) for introducing a substance containing at least nitrogen into the reaction vessel 101, and a region where the mixed melt contacts the mixed melt holding vessel 102 is It is characterized by having sufficient purity with few impurities.

As described above, according to the present invention, the region where the mixed melt contacts the mixed melt holding vessel 102 has sufficient purity with a small amount of impurities, so that the entire surface of the mixed melt is covered with the solid material. And promotes the continuous dissolution of nitrogen into the mixed melt, III
Crystal growth of the group nitride crystal can be continued. Further, by reducing the amount of Group III metal constituting the solid,
The consumption of the group II metal on the surface of the mixed melt can be reduced, and a large amount of the group III metal can be supplied to the group III nitride crystal in the mixed melt. As a result, it is possible to grow a large group III nitride crystal of a desired size. Further, impurities contained in the mixed melt are reduced, and the crystal quality of the obtained group III nitride single crystal is improved.

As shown in FIG. 6, the same type of I-nitride (eg, GaN) as a III-nitride (for example, GaN) crystal-grown by a III-nitride crystal growth apparatus is provided inside mixed-liquid holding vessel 102.
Group II nitride 115 (for example, GaN) can be applied (coated) in advance. In this case, impurities can be further reduced, and a higher quality group III nitride crystal (for example, GaN) can be grown.

Further, in the example shown in FIG.
Although 02 is provided separately from the reaction vessel 101, the reaction vessel 101 and the mixed melt holding vessel 102 may be integrated. FIG. 7 is a diagram showing another configuration example of the group III nitride crystal growth apparatus according to the present invention. In FIG. 7, the same parts as those in FIG. 1 are denoted by the same reference numerals. Referring to FIG. 7, in this group III nitride crystal growing apparatus,
The reaction container of FIG. 1 and the mixed melt holding container are configured as an integral unit. That is, the reaction container 200 is constituted by the container outer wall 201 and the container inner wall 202 for substantially holding the mixed melt.

Here, the vessel outer wall 201 corresponds to the reaction vessel 101 of FIG. 1, and is made of, for example, stainless steel.

The container inner wall 202 corresponds to the mixed melt holding container 102 shown in FIG. 1, and is made of BN, AlN, or pyrolytic BN. However, as the material of the container inner wall 202, as described above, BN is better than AlN, and BN is better.
Pyrolytic BN is better than BN.

In the case of the configuration shown in FIG. 7, the nitrogen supply pipe 104 is introduced into the reaction vessel 200 from above or from the side of the reaction vessel 200. FIG.
1, similarly to FIG. 1, the nitrogen supply pipe 104 is provided with a pressure adjusting mechanism 105 for adjusting the pressure of the nitrogen gas.

In the group III nitride crystal growth apparatus having the structure shown in FIG. 7, a mixture of an alkali metal (eg, Na) and a substance containing at least a group III metal (eg, Ga) is formed in the inner wall 202 of the reaction vessel 200. A melt is formed, and a substance containing at least nitrogen (for example, nitrogen gas, ammonia gas or sodium azide) is supplied from the nitrogen supply pipe 104 to the space 208 in the reaction vessel 200, and is made of a group III metal and nitrogen. A group III nitride (for example, GaN) is grown.

At this time, as described above, the purity of the alkali metal and / or the purity of the substance containing the group III metal and / or the purity of the substance containing nitrogen are determined by at least one of the surfaces of the mixed melt. Polycrystalline or non-quality II
It must be of the purity required to be not covered with Group I nitride.

Specifically, a group III nitride (for example, GaN) can be grown in the same manner as in the first, second, third, or fourth embodiment described above.
The same effect as in the first, second, third or fourth embodiment can be obtained.

In other words, the apparatus for growing a group III nitride crystal in FIG. 7 includes a reaction vessel 200 for holding a mixed melt of an alkali metal and a substance containing at least a group III metal, and at least nitrogen in the reaction vessel 200. Nitrogen introduction means (104, 105) for introducing a substance containing
The reaction vessel 200 is composed of a vessel outer wall 201 and a vessel inner wall 202 for substantially holding the mixed melt, and a region where the mixed melt is in contact with the vessel inner wall 202 has sufficient purity with few impurities. It is characterized by having.

As described above, in the group III nitride crystal growth apparatus shown in FIG. 7, the region where the mixed melt contacts the inner wall 202 of the container is:
Since the impurity has sufficient purity with few impurities, it is possible to prevent the entire surface of the mixed melt from being covered by the solid substance, thereby continuously dissolving nitrogen into the mixed melt, The crystal growth of the group III nitride crystal can be continued. Furthermore, since the amount of the group III metal constituting the solid is reduced, the consumption of the group III metal on the surface of the mixed melt can be reduced, and the group III metal in the group III nitride crystal in the mixed melt contains a large amount of the group III metal. It becomes possible to supply. As a result, it is possible to grow a large group III nitride crystal of a desired size. Further, impurities contained in the mixed melt are reduced, and the crystal quality of the obtained group III nitride single crystal is improved.

As shown in FIG. 8, in the group III nitride crystal growth apparatus shown in FIG.
A group III nitride 215 similar to a group III nitride (for example, GaN) grown by a group III nitride crystal growing apparatus
(Eg, GaN) may be applied (coated) in advance. In this case, impurities can be further reduced, and a higher quality group III nitride crystal (for example, GaN) can be grown.

As described above, according to the present invention, a low-cost, high-quality group III nitride crystal of a practical size for manufacturing high-performance devices such as light-emitting diodes and LDs is manufactured. And can be provided.

Therefore, by using the high quality group III nitride crystal of practical size obtained in this way, high quality,
A high-performance group III nitride semiconductor device can be manufactured. Note that the high performance referred to here is, for example, a semiconductor laser or a light emitting diode that has a high output and a long life, which has not been realized conventionally, and a low power consumption, low noise, and It is capable of high-speed operation and high-temperature operation, and in the case of a light receiving device, has low noise, long life, and the like.

For example, a semiconductor light emitting device that emits light at a wavelength shorter than 400 nm can be manufactured as a group III nitride semiconductor device. That is, in the prior art, the emission spectrum of the GaN film from the deeper order becomes dominant, and there is a problem that the device characteristics are poor at a wavelength shorter than 400 nm. However, the present invention has good characteristics even in the ultraviolet region. A light emitting device can be provided. That is, the high quality III obtained by the present invention
By using a group III nitride crystal for the substrate, it becomes possible to realize a group III nitride semiconductor device with few crystal defects and impurities, and as a result, to achieve high-efficiency light emission characteristics in which light emission from a deep order is suppressed. Becomes possible.

FIG. 9 is a diagram showing an example of a group III nitride semiconductor device manufactured using the group III nitride crystal obtained according to the present invention. In the example of FIG. 9, the group III nitride semiconductor device is It is configured as a semiconductor laser. FIG.
With reference to this, a group III nitride semiconductor device is provided with an n-type AlGaN on an n-type GaN substrate 501 manufactured using a group III nitride crystal (GaN) obtained according to the present invention.
Clad layer 502, n-type GaN guide layer 503, InG
aN MQW (multiple quantum well) active layer 504, p-type Ga
N guide layer 505, p-type AlGaN cladding layer 506,
A p-type GaN contact layer 507 is formed as a stacked structure by sequentially growing crystals. As the crystal growth method, MO-VPE (metal organic chemical vapor deposition) method and M
A thin film crystal growth method such as a BE (molecular beam epitaxy) method can be used.

Then, a ridge structure is formed in the laminated structure, and the SiO ₂ insulating film 508 is formed in a state where only the region of the contact layer 507 is removed.
On p. 07, a p-side ohmic electrode Al / Ni 509 is formed. An n-side ohmic electrode Al / Ti 510 is formed on the back surface of the substrate 501.

In this semiconductor laser, the p-side ohmic electrode Al / Ni 509 and the n-side ohmic electrode Al / Ti
By injecting current from 510, laser oscillation occurs, and laser light is emitted in the direction of the arrow in the figure.

Since this semiconductor laser uses the GaN crystal obtained by the present invention as the substrate 501, it has few crystal defects in the semiconductor laser device, has a large output operation, and has a long life. Further, since the GaN substrate 501 is n-type, an electrode can be formed directly on the substrate 501, and two electrodes on the p-side and the n-side are formed only from the surface as in the first related art (FIG. 10). Without having to take it out,
Cost reduction can be achieved. Further, the light emitting end face can be formed by cleavage, and together with chip separation, a low-cost, high-quality device can be realized.

In the example of FIG. 9, the InGaN MQW
Is used as the active layer 504, but it is also possible to shorten the emission wavelength by using the AlGaN MQW as the active layer 504. In any case, in the example of FIG.
Since the number of defects and impurities in 1 is small, light emission from a deep order is reduced, and a highly efficient light-emitting device can be realized even if the wavelength is shortened. That is, it becomes easy to manufacture a light emitting device having a shorter emission wavelength.

In the above-described example, the application of the group III nitride crystal obtained by the present invention to an optical device has been described. However, the group III nitride crystal obtained by the present invention is applied to an electronic device. Can also. That is, by using a GaN substrate with few defects, the GaN-based thin film epitaxially grown thereon also has few crystal defects, and as a result,
Leakage current can be suppressed, the effect of confining carriers in a quantum structure can be enhanced, and a high-performance device can be realized.

[0110]

As described above, according to the first to eighth aspects of the present invention, a mixed melt of an alkali metal and a substance containing at least a group III metal is formed in a predetermined container. A group III nitride crystal growth method for growing a group III nitride composed of a group III metal and nitrogen from the mixed melt and a substance containing at least nitrogen, wherein the surface of the mixed melt is mixed and melted. The group III nitride is grown in a state in which nitrogen can be introduced into the liquid, so it is of a practical size for manufacturing devices such as high performance light emitting diodes and LDs, and is low cost and high quality. Can be grown. In other words, the surface of the mixed melt is brought into a state in which nitrogen can be introduced into the mixed melt, and by growing a group III nitride, nitrogen can be efficiently dissolved into the mixed melt. , II in the mixed melt
The growth of the group I nitride single crystal continues, and it becomes possible to obtain a large-sized group III nitride crystal.

In particular, according to the second aspect of the present invention, the first aspect
In the method for growing a group III nitride crystal, the purity of the alkali metal and / or the purity of a substance containing a group III metal and / or the purity of a substance containing nitrogen is at least one of the surface of the mixed melt. The part has the purity necessary to prevent it from being covered with polycrystalline or non-quality Group III nitrides. Crystal growth can be continued. Furthermore, since the amount of the group III metal constituting the solid material (polycrystalline or non-quality group III nitride) is reduced, the consumption of the group III metal on the surface of the mixed melt can be reduced. A large amount of group III metal can be supplied to the group III nitride crystal. As a result, it is possible to grow a large group III nitride crystal of a desired size. In addition, since the impurities contained in the mixed melt are reduced, the crystal quality of the obtained group III nitride single crystal is also improved.

Also, claims 9 to 11, and claim 1
The invention according to claims 6 to 18, wherein the mixed melt holding container for holding a mixed melt of an alkali metal and a substance containing at least a Group III metal, a reaction container provided with the mixed melt holding container, At least nitrogen introducing means for introducing a substance containing at least nitrogen into the container, the region where the mixed melt is in contact with the mixed melt holding container,
By having sufficient purity with few impurities, it is possible to prevent the entire surface of the mixed melt from being covered with a solid substance (polycrystalline or non-quality Group III nitride), thereby making it possible to mix The continuous dissolution of nitrogen into the melt proceeds, and the crystal growth of the group III nitride crystal can be continued. Furthermore, since the amount of the group III metal constituting the solid material is reduced, the consumption of the group III metal on the surface of the mixed melt can be reduced, and the group III nitride crystal in the mixed melt has
A large amount of group metal can be supplied. As a result, it is possible to grow a large group III nitride crystal of a desired size. In addition, since the impurities contained in the mixed melt are reduced, the crystal quality of the obtained group III nitride single crystal is also improved.

According to the twelfth aspect of the present invention, there is provided a reaction vessel for holding a mixed melt of an alkali metal and a substance containing at least a group III metal, and the reaction vessel containing at least nitrogen. At least nitrogen introducing means for introducing a substance, the reaction vessel is constituted by a vessel outer wall, and a vessel inner wall for substantially holding the mixed melt, wherein the mixed melt is Since the region in contact with the inner wall of the container has sufficient purity with few impurities, it is necessary to prevent the solid (polycrystalline or non-quality Group III nitride) from covering the entire surface of the mixed melt. Thereby, the continuous dissolution of nitrogen into the mixed melt proceeds, and the crystal growth of the group III nitride crystal can be continued. Furthermore, since the amount of the group III metal constituting the solid is reduced, the consumption of the group III metal on the surface of the mixed melt can be reduced, and the group III metal in the group III nitride crystal in the mixed melt contains a large amount of the group III metal. It becomes possible to supply. As a result, it is possible to grow a large group III nitride crystal of a desired size. In addition, the amount of impurities contained in the mixed melt is reduced, thereby obtaining III.
The crystal quality of the group III nitride single crystal is also improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a group III nitride crystal growth apparatus according to the present invention.

FIG. 2 is a diagram for explaining a first embodiment of the present invention.

FIG. 3 is a diagram for explaining a second embodiment of the present invention.

FIG. 4 is a diagram for explaining a third embodiment of the present invention.

FIG. 5 is a diagram for explaining a fourth embodiment of the present invention.

FIG. 6 shows a group III nitride crystal growth apparatus of FIG. 1 in which a group III nitride of the same kind as the group III nitride grown by the group III nitride crystal growth apparatus is previously placed inside a mixed melt holding vessel. FIG. 3 is a diagram illustrating a configuration in which coating is performed.

FIG. 7 is a diagram showing another configuration example of the group III nitride crystal growth apparatus according to the present invention.

FIG. 8: In the III-nitride crystal growth apparatus of FIG. 7, a III-nitride of the same type as the III-nitride crystal grown by the III-nitride crystal growth apparatus is applied in advance to the inner wall of the container. FIG. 2 is a diagram showing a configuration to be put.

FIG. 9 is a diagram showing an example of a group III nitride semiconductor device manufactured using a group III nitride crystal obtained according to the present invention.

FIG. 10 is a diagram showing a conventional laser diode.

FIG. 11 is a view showing a conventional semiconductor laser.

FIG. 12 is a diagram illustrating a method of manufacturing a GaN thick film substrate according to a sixth conventional technique.

FIG. 13 is a view illustrating a method of manufacturing a GaN thick film substrate according to a sixth conventional technique.

[Explanation of symbols]

Reference Signs List 101 Reaction vessel 102 Mixed melt holding vessel 103 Mixed melt 104 Nitrogen supply pipe 105 Pressure adjusting mechanism 106 Heating device 108 Space in reaction vessel 109 Group III nitride (G
aN) Crystal 115 Group III nitride 200 Reaction vessel 201 Container outer wall 202 Container inner wall 208 Space in reaction vessel 215 Group III nitride 501 n-type GaN substrate 502 n-type AlGaN cladding layer 503 n-type GaN guide layer 504 InGaN MQ
W active layer 505 p-type GaN guide layer 506 p-type AlGaN cladding layer 507 p-type GaN contact layer 508 SiO ₂ insulating film 509 p-side ohmic electrode 510 n-side ohmic electrode

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G077 AA02 BE15 CC04 CC06 EA06 EC07 EG02 5F041 AA40 AA44 CA40 CA63 FF11 FF13 5F073 BA06 BA09 CA01 CB02 DA02 DA04 DA06 DA35

Claims (18)

[Claims] In a predetermined container, a mixed melt of an alkali metal and a substance containing at least a group III metal is formed, and the mixed melt is mixed with a substance containing at least nitrogen.
A group III nitride crystal growth method for growing a group III nitride composed of a group I metal and nitrogen, comprising: bringing a surface of a mixed melt into a state in which nitrogen can be introduced into the mixed melt; A method for growing a group III nitride crystal, comprising growing a nitride. 2. The method for growing a group III nitride crystal according to claim 1, wherein the purity of the alkali metal and / or the purity of a substance containing a group III metal and / or the purity of a substance containing nitrogen are: A group III nitride crystal growth method, characterized in that at least a part of the surface of the mixed melt has a purity required to be not covered with polycrystal or non-quality group III nitride. 3. The method for growing a group III nitride crystal according to claim 1, wherein the alkali metal includes N.
a group III nitride crystal growth method, wherein a is used. 4. The group III nitride crystal growth method according to claim 1, wherein the group III metal is Ga
A method for growing a group III nitride crystal, comprising: 5. The group III nitride crystal growth method according to claim 1, wherein the substance containing at least nitrogen is nitrogen gas, ammonia gas or sodium azide. Nitride crystal growth method. 6. The method for growing a group III nitride crystal according to claim 1, wherein the predetermined container is formed of BN. 7. The method for growing a group III nitride crystal according to claim 1, wherein the predetermined container is made of AlN.
A group III nitride crystal growth method, characterized by being formed by: 8. The method for growing a group III nitride crystal according to claim 1, wherein the predetermined container is formed of pyrolytic BN.
Group nitride crystal growth method. 9. A mixed melt holding vessel for holding a mixed melt of an alkali metal and a substance containing at least a Group III metal,
A reaction vessel in which the mixed melt holding vessel is installed, and at least nitrogen introducing means for introducing a substance containing nitrogen into the reaction vessel, wherein the mixed melt is a mixed melt holding vessel; A group III nitride crystal growth apparatus, characterized in that the contacting region has a sufficient purity with few impurities. 10. The group III nitride crystal growing apparatus according to claim 9, wherein said mixed melt holding vessel is formed of pyrolytic BN. 11. The group III nitride crystal growth apparatus according to claim 9, wherein said mixed melt holding vessel has
A group III nitride crystal growth apparatus characterized in that a group III nitride of the same kind as a group III nitride grown by a group nitride crystal growth apparatus is applied in advance. 12. A reaction vessel holding a mixed melt of an alkali metal and a substance containing at least a group III metal, and at least nitrogen introducing means for introducing a substance containing at least nitrogen into the reaction vessel. The reaction vessel is constituted by a vessel outer wall and a vessel inner wall for substantially holding the mixed melt, and a region where the mixed melt is in contact with the vessel inner wall has sufficient purity with few impurities. A group III nitride crystal growth apparatus, comprising: 13. The group III nitride crystal growing apparatus according to claim 12, wherein the outer wall of the container is formed of stainless steel. 14. The group III nitride crystal growing apparatus according to claim 12, wherein the inner wall of the container is a pyrolytic BN.
A group III nitride crystal growth apparatus characterized by being formed by: 15. The group III nitride crystal growth apparatus according to claim 12, wherein the same type of group III nitride as the group III nitride crystal grown by the group III nitride crystal growth apparatus is provided inside the container inner wall. A group III nitride crystal growth apparatus, wherein is coated in advance. 16. III according to claim 9 or claim 12.
A group III nitride crystal growth apparatus, wherein Na is used as the alkali metal. 17. III according to claim 9 or claim 12.
In the group nitride crystal growth apparatus, the group III metal includes
An apparatus for growing a group III nitride crystal, wherein Ga is used. 18. The method according to claim 9 or 12, wherein
A group III nitride crystal growth apparatus, characterized in that the substance containing at least nitrogen is nitrogen gas, ammonia gas or sodium azide.