TWI427200B - A method for producing a nitride single crystal and an autoclave for use in the same - Google Patents

Description

Method for producing nitride single crystal and autoclave therefor

The present invention relates to a method for producing a nitride single crystal using an ammoniacal method as a solvothermal method, and a novel autoclave therefor. More specifically, the present invention relates to a novel method for producing a nitride single crystal of a bulk single crystal containing a Ga-containing nitride using an acidic mineralizer in an ammoniacal method using an ammonia solvent, and An autoclave for the manufacturing method.

GaN (gallium nitride) crystals are used for light-emitting elements such as light-emitting diodes and laser diodes. Such a light-emitting element utilizes a nitride of a Group 13 element of the periodic table such as Al, Ga, In, or specifically a nitride of a group 13 element such as AlN, GaN or InN, or a group 13 element containing a mixture of a plurality of 13 elements. Crystallization of nitrides.

A general method for producing a nitride film for a light-emitting element is a method of using a sapphire or tantalum carbide or the like as a substrate for heteroepitaxial growth. In this method, defects such as misalignment defects occur in the nitride film due to the difference between the lattice constant of the sapphire substrate or the tantalum carbide substrate and the lattice constant of the nitride film. This defect causes the characteristics of the light-emitting element to decrease. When a high-purity and high-quality group 13 element nitride crystal is obtained, it is used as a substrate, whereby a nitride film having no difference in lattice constant from the substrate can be grown on the substrate. According to the high-quality nitride crystal of the group 13 element, it is expected that the efficiency of the light-emitting element using the group 13 element nitride semiconductor and the expansion of the group 13 element nitride semiconductor in power semiconductor applications and the like can be expected.

For example, as a method of producing a GaN bulk single crystal, a high temperature and high pressure method, a HVPE (Hydride Vapor Phase Epitaxy) method, a flux method, a sublimation method, and the like are reported. However, the crystallization growth technique is not simple and has not yet reached GM. GaN independent substrates using the HVPE method have begun to be sold. However, GaN independent substrates using the HVPE method have not yet reached a practical level due to problems such as high price of the GaN independent substrate, and the peeling method of GaN and the substrate for growing the same, and the warpage of the grown crystal. .

The solvothermal method is a general term for a crystal production method using a solvent in a supercritical state and/or a subcritical state, and is called a hydrothermal method especially when water is used as a solvent, and is called a case where ammonia is used as a solvent. Ammonia method. The hydrothermal method is widely used as an industrial manufacturing method for artificial crystals, and is one of methods for obtaining high quality crystals.

The ammonothermal method is expected as a method for producing a nitride bulk single crystal such as GaN. The ammoniacal method is a method in which ammonia is used as a solvent, temperature and pressure are adjusted to dissolve or react a raw material, and crystal growth is carried out by utilizing, for example, temperature dependency of solubility. In the same manner as the artificial crystal by the hydrothermal method, it is expected to industrially produce a high-quality bulk single crystal by the ammoniacal method.

In the ammoniacal method, in order to produce a nitride bulk single crystal such as GaN, it is known that it is effective to add a mineralizer. The term "mineralizer" refers to an additive used to increase the solubility of a raw material in supercritical ammonia and promote crystal growth. The mineralizer is mainly classified into an acidic mineralizer having an effect of lowering the pH of the solvent when dissolved in ammonia as a solvent, and an alkaline mineralizer having an effect of increasing the pH of the solvent.

For example, Patent Document 1 discloses a method of obtaining a GaN bulk single crystal by selective crystallization on a seed crystal by an ammoniacal method using an alkaline mineralizer.

On the other hand, in the case of using an acidic mineralizer, single crystal growth by the ammonothermal method can be carried out by using an autoclave which is internally lined with a noble metal such as platinum. Non-Patent Document 1 discloses that GaN crystals are obtained by an ammoniacal method using NH ₄ Cl as an acid mineralizer and using an autoclave lined with platinum at a pressure of about 200 MPa.

Patent Document 2 describes an ammoniacal method using an acidic mineralizer. In the method described in Patent Document 2, an autoclave including a raw material filling portion and a crystal growth portion of the upper portion separated by a baffle is used. The lower portion is mainly filled with a material containing a nitride polycrystal, and a seed crystal is disposed on the upper portion. The temperature of the upper portion is kept lower than the temperature of the lower portion, whereby the seed crystal is grown in the low temperature region of the upper portion.

It is known that preferred crystal growth conditions are quite different in the case of using an acidic mineralizer and in the case of using an alkaline mineralizer. It is known that, for example, when an alkaline mineralizer is used in the ammoniacal method, a relatively high pressure of about 150 to 500 MPa is required. In contrast, when an acidic mineralizer is used, it is relatively low as long as about 100 to 200 MPa. The pressure can be. Further, in the case of using an acidic mineralizer and the case of using an alkaline mineralizer, the corrosion resistance required for the autoclave is different. As described above, in the nitride single crystal manufacturing technique using the ammonothermal method, the single crystal production conditions are greatly different depending on whether the mineralizer used is acidic or alkaline.

As described in Patent Document 3, when an acid mineralizer is used to grow a nitride single crystal on a seed crystal by an ammoniacal method, the raw material polycrystal is placed under the autoclave, and the seed is placed. The crystal is disposed on the upper portion of the autoclave. On the other hand, in the case of using an alkaline mineralizer, the arrangement is reversed. Previously, the above-described arrangement conditions were considered to be general growth conditions of a nitride single crystal using an ammoniacal method.

On the other hand, the industry is investigating a method of not using a seed crystal, that is, a method in which a crystallite obtained by an aromatization method and obtained by spontaneous nucleation is used as a raw material for crystal growth to be performed next (for example, refer to the patent literature) 4).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-533391

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-120672

[Patent Document 3] US Application Publication No. 20100303704

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2008-143778

[Non-patent literature]

[Non-Patent Document 1] XL Chenm, YG Cao, YC Lan, XP Xu, JQ Lu, PZ Jiang, T. Xu, ZG Bai, YD Yu, JK Liang, "Journal of Crystal Growth", Vol. 209, 2000 Year, p. 208-212

However, the crystallites obtained by spontaneous nucleation cannot be used as seed crystals because of the powder size of several micrometers. Therefore, it has not previously been possible to obtain a seed crystal used in the ammonothermal method by spontaneous nucleation using an ammoniacal method.

Although various studies as described above have been carried out, the growth technique of the nitride single crystal by the ammonothermal method cannot be said to have been sufficiently completed. In order to carry out the growth technology of the nitride single crystal by the ammoniacal method in the industry, it is necessary to use a faster growth rate to improve productivity and a higher crystal quality, and there are many problems to be solved, which is true.

For example, in the case of gallium nitride, in the previously reported nitride single crystal growth technique using the ammoniacal method, the growth rate is 30 μm/day to several micrometers/day, in competition with the HVPE method and the flux method. slower. In the prior art, it is difficult to make the faster growth rate and the smooth growth coexist.

Accordingly, the object of the present invention is to provide a novel method for producing a nitride single crystal which can utilize a relatively high crystal growth rate and a higher crystal quality by utilizing an ammoniacal method, and to provide a novel method which can be used in the method. Autoclave. Further, it is an object of the present invention to provide an autoclave with a noble metal lining which does not cause peeling of a precious metal lining, crack generation, abrasion, and the like, and which can maintain pressure even if it is used repeatedly.

In order to solve the above problems, the inventors of the present invention have diligently studied and repeatedly conducted experiments, and found that in the ammoniacal method using an acidic mineralizer, a higher crystal growth temperature than the previous one is used, and the arrangement of the raw materials in the autoclave is The relationship between the temperature and the position between the crystal growth sites is set to be different from the conventional prior art using an acidic mineralizer, whereby a faster crystal growth rate and a higher crystal quality can be coexisted. That is, the temperature (T1) of the single crystal growth portion is set to be higher than the temperature (T2) of the material supply portion (T1>T2) at 600 to 850 ° C which is a higher crystal growth temperature than before. Further, in the autoclave, a material of a shield portion that is a part that holds the pressure between the two or more components constituting the autoclave and that is a part of the autoclave is formed of an alloy of ruthenium and platinum or a ruthenium monomer, and is shielded from the shield portion. The proportion of the constituent elements of the material is 20% by mass to 100% by mass. Thereby, it was found that the shield portion has good hardness and can improve the number of times of repeated use of the autoclave with a precious metal lining. That is, the present invention is as follows.

[1] A method for producing a nitride single crystal, comprising a material comprising at least one selected from the group consisting of a polycrystal containing Ga, a nitride containing Ga, and a nitride precursor containing Ga, A method for producing a Ga-containing nitride single crystal by an ammoniacal method, comprising the steps of:

After introducing at least the raw material, one or more acidic mineralizers, and ammonia into the autoclave, the Ga-containing nitride single crystal is grown under the following conditions (a) to (e):

(a) a raw material supply portion where the raw material is disposed and a single crystal growth portion for growing the Ga-containing nitride single crystal in the autoclave;

(b) the single crystal growth portion is provided with a seed crystal portion,

(c) the temperature (T1) of the grown portion of the single crystal is 600 ° C to 850 ° C,

(d) a relationship between the temperature (T1) of the single crystal growth portion and the temperature (T2) of the raw material supply portion is T1>T2, and

(e) The pressure in the autoclave is 40 MPa to 250 MPa.

[2] A method for producing a nitride single crystal, comprising a material comprising at least one selected from the group consisting of a Ga-containing nitride polycrystal, a Ga-containing nitride, and a Ga-containing nitride precursor. A method for producing a Ga-containing nitride single crystal by an ammoniacal method, comprising the steps of:

After introducing at least the raw material, one or more acidic mineralizers, and ammonia into the autoclave, the Ga-containing nitride single crystal is grown under the following conditions (a) to (e):

(a) a raw material supply portion where the raw material is disposed and a single crystal growth portion for growing the Ga-containing nitride single crystal in the autoclave;

(b) the single crystal growth site is a portion where the Ga-containing nitride single crystal is precipitated and grown by spontaneous nucleation.

(c) the temperature (T1) of the grown portion of the single crystal is 600 ° C to 850 ° C,

(d) a relationship between the temperature (T1) of the single crystal growth portion and the temperature (T2) of the raw material supply portion is T1>T2, and

(e) The pressure in the autoclave is 40 MPa to 250 MPa.

[3] The method for producing a nitride single crystal according to the above [1], wherein the seed crystal is a Ga-containing nitride single crystal produced by the method for producing a nitride single crystal according to [2] above.

[4] The method for producing a nitride single crystal according to any one of the above [1] to [3] wherein the raw material is disposed in a container provided with a plurality of holes or slit-like gaps, and in the container There is a gap of 1 mm or more between the side surface and the inner wall of the autoclave.

[5] The method for producing a nitride single crystal according to any one of the above [1] to [4] wherein the autoclave is a vertical autoclave, and the raw material supply portion is present in the growth portion of the single crystal. High position.

[6] The method for producing a nitride single crystal according to the above [5], wherein the raw material supply portion is present at a position of 10 mm or more from the inner bottom surface of the autoclave, and the single crystal growth portion is present. Between the raw material supply portion and the inner bottom surface of the autoclave.

[7] The method for producing a nitride single crystal according to any one of the above [1] to [6] wherein at least one spacer is disposed between the raw material supply portion and the single crystal growth portion.

[8] The method for producing a nitride single crystal according to any one of the above [2], wherein the single crystal growth site is a single crystal of a Ga-containing nitride by spontaneous nucleation A plate having precipitation and growth, and a plate having corrosion resistance of one or more holes is disposed in the single crystal growth portion.

[9] The method for producing a nitride single crystal according to any one of the above [1] to [8] wherein the raw material comprises a Ga-containing nitride polycrystal produced by a vapor phase method.

[10] A substrate comprising a nitride single crystal produced by the method for producing a nitride single crystal according to any one of the above [1] to [9].

[11] A nitride single crystal produced by the method for producing a nitride single crystal according to any one of the above [1] to [9], wherein the maximum size is 1 mm or more.

[12] An autoclave for use in a method for producing a nitride single crystal according to any one of the above [1] to [9], wherein the two or more parts constituting the autoclave are closely adhered to each other. The portion of the pressure in the autoclave, that is, the material of the shield portion is an alloy of platinum or rhodium, and the proportion of the constituent elements of the material of the shield portion is 20% by mass to 100% by mass.

According to the method for producing a nitride single crystal of the present invention, the growth of a nitride single crystal excellent in crystal quality can be achieved at a faster crystal growth rate (for example, 30 μm/day or more). Further, since the nitride single crystal obtained by the production method of the present invention has a flat film-like growth layer, it can be obtained as a bulk nitride single crystal in which a substrate having various crystal orientations can be cut out.

Further, according to the method for producing a nitride single crystal of the present invention, a single crystal grain of a size which can be treated by spontaneous nucleation can be easily obtained. The resulting single crystal grains may have a size of, for example, a maximum size of 1 mm or more, and thus may be used as a seed crystal.

Further, in the autoclave of the present invention, the material of the shield portion is composed of an alloy of ruthenium and platinum or a ruthenium monomer, and the proportion of the constituent elements of the material is 20% by mass to 100% by mass. . Since the shield portion is configured as described above, the hardness of the shield portion is particularly improved. Therefore, even if a force is applied to the shield portion, the shield portion is less likely to cause abrasion and scratches, even at a temperature of 600 to 850 ° C as contemplated by the method of the present invention. Under the conditions, the autoclave can also be used repeatedly. Specifically, when an alloy of ruthenium and platinum or a ruthenium monomer is used as the material of the shield portion, the shield portion is not melted and adhered to each other at a temperature of 850 ° C or lower. Therefore, when the lid of the autoclave is opened, the shield material is not peeled off. Or rupture. Therefore, the autoclave of the present invention can maintain the pressure even if it is repeatedly used under high temperature conditions of 600 to 850 °C.

Hereinafter, a more specific aspect of the present invention will be described in detail. Furthermore, the following description is based on representative embodiments of the present invention, but the present invention is not limited to the embodiments.

<Method for Producing Nitride Single Crystal>

One aspect of the present invention provides a method for producing a nitride single crystal, comprising at least one selected from the group consisting of a polycrystal containing Ga, a nitride containing Ga, and a nitride precursor containing Ga. A method for producing a Ga-containing nitride single crystal by an ammoniacal method, comprising the steps of: introducing at least the raw material, one or more acidic mineralizers, and ammonia into the autoclave, and satisfying the following (a)~ Under the condition of (e), the growth of the nitride crystal containing Ga is made:

(a) a raw material supply portion where the raw material is disposed and a single crystal growth portion for growing the Ga-containing nitride single crystal in the autoclave;

(b) the single crystal growth portion is provided with a seed crystal portion,

(c) the temperature (T1) of the grown portion of the single crystal is 600 ° C to 850 ° C,

(d) a relationship between the temperature (T1) of the single crystal growth portion and the temperature (T2) of the raw material supply portion is T1>T2, and

(e) The pressure in the autoclave is 40 MPa to 250 MPa.

Another aspect of the present invention provides a method for producing a nitride single crystal, comprising at least one selected from the group consisting of a Ga-containing nitride polycrystal, a Ga-containing nitride, and a Ga-containing nitride precursor. A method for producing a Ga-containing nitride single crystal by an ammoniacal method, comprising the steps of: introducing at least the raw material, one or more acidic mineralizers and ammonia into the autoclave, and satisfying the following (a) Under the condition of ~(e), a single crystal containing Ga is grown:

(a) a raw material supply portion where the raw material is disposed and a single crystal growth portion for growing the Ga-containing nitride single crystal in the autoclave;

(b) the single crystal growth site is a portion where the Ga-containing nitride single crystal is precipitated and grown by spontaneous nucleation.

(c) the temperature (T1) of the grown portion of the single crystal is 600 ° C to 850 ° C,

(d) a relationship between the temperature (T1) of the single crystal growth portion and the temperature (T2) of the raw material supply portion is T1>T2, and

(e) The pressure in the autoclave is 40 MPa to 250 MPa.

In this specification, the Ga-containing nitride contains GaN (gallium nitride) and contains Ga and other elements (typically the Group 13 element of the periodic table (IUPAC (International Union of Pure and Applied Chemistry). Chemical Federation), 1989), also referred to below as a nitride of Group 13 elements. That is, the Ga-containing nitride to which the present invention is intended includes not only a nitride of a single metal such as GaN but also a polyvalent compound such as AlGaN, InGaN, or AlInGaN. Furthermore, these chemical formulas only represent constituent elements of the nitride and do not indicate the composition ratio.

Examples of the Ga-containing nitride single crystal produced by the present invention include GaN; a mixed crystal of GaN and other Group 13 element nitrides; and a polynitride containing Ga and other Group 13 elements. Examples of the polynitride include AlGaN, InGaN, and AlInGaN. Examples of the mixed crystal include a mixed crystal of a group 13 element nitride containing BN, AlN, GaN, and InN.

In the present invention, the term "polycrystalline" means a solid obtained by various appearances such as a bulk, a granule, or a powder, and most of the minute single crystals, that is, the crystallites exist in an inseparable form toward mutually different orientations. State. The degree of merging of the size of the crystallites and the orientation of the crystallites, that is, the degree of orientation, is not particularly limited.

In the present invention, a raw material containing at least one selected from the group consisting of Ga-containing nitride polycrystals, Ga-containing nitrides, and Ga-containing nitride precursors is used. The raw material is typically a polycrystal containing a nitride containing Ga, and more typically consists of a polycrystal containing a nitride of Ga. However, the raw material does not have to contain only complete nitrides, for example, it may also contain zero-valent metals.

Further, the nitride polycrystal and the nitride single crystal disclosed in the present specification may contain magnesium, zinc, carbon, and ruthenium in a very small amount ranging from 1/10 to 1/1,000,000 with respect to the molar amount of the group 13 element. , bismuth, etc. as doping materials.

The nitride containing Ga is supplied as a raw material in a state of being polycrystalline or not polycrystalline. As the nitride containing Ga, GaN which is a nitride of a single element, and AlGaN which is a polynitride can be exemplified. The raw materials may also be a mixture. For example, a mixture of a Ga-containing nitride and a Ga-free nitride may be used, and a mixture of one or more selected from the group consisting of BN, AlN, and InN and GaN may be preferably exemplified. A mixture of AlN and GaN is a more typical preferred embodiment.

As the precursor of the Ga-containing nitride, gallium nitride, gallium sulfide, gallium amidoxime, gallium hydride, gallium-containing alloy, metal gallium or the like can be exemplified. The raw materials may also be a mixture. For example, a mixture of a precursor of a nitride containing Ga and an aluminide, an aluminide, a potassium sulfimine, an indium decylamine, an indium sulfimine, or the like can be exemplified. These are nitrided in supercritical ammonia to form a single crystal.

Further, each compound used as a raw material is preferably of high purity. On the other hand, since the raw material is dissolved in the ammonia solvent at the time of use, the crystallinity does not need to be high.

The method for producing a nitride polycrystal used as a raw material is not particularly limited. However, from the viewpoint of a raw material having less impurities, the raw material preferably contains a Ga-containing nitride polycrystal produced by a vapor phase method. More preferably, the raw material contains a Ga-containing nitride polycrystal produced by a vapor phase method. For example, in the case of GaN, a nitride polycrystal can be produced by a method of nitriding metal gallium or Ga ₂ O ₃ with ammonia. Alternatively, as in the HVPE method, nitride polycrystals can be obtained by the reaction of a halide with ammonia.

In the present invention, ammonia is used as the solvent, but the less the amount of impurities contained in the ammonia, the better. The purity of the ammonia used is usually 99.9% by mass or more, preferably 99.99% by mass or more, and more preferably 99.999% by mass or more.

The method of the present invention is carried out in an autoclave to produce a Ga-containing nitride single crystal by an ammoniacal method (i.e., supercritical crystallization) in the presence of ammonia, more specifically, in an ammonia atmosphere. The ammonothermal method is, for example, the method disclosed in the above-mentioned Patent Document 1, Non-Patent Document 1, and the like.

The crystal growth time is typically from 1 day to 1 year, more preferably from 2 days to 6 months.

The ammonia system functions as a solvent to form an ammonia gas atmosphere during the reaction. The ammonia gas environment can be formed by nitrogen and hydrogen generated by thermal decomposition of pure ammonia and/or ammonia, and further contains an acidic mineralizer.

The acidic mineralizer added to the ammonia used as a solvent may, for example, be a compound containing a halogen element, and examples thereof include an ammonium halide. Examples of the ammonium halide include ammonium chloride, ammonium iodide, ammonium bromide, and ammonium fluoride. In particular, ammonium chloride is preferred as a raw material for ease of purchase and ease of handling.

The proportion of the mineralizer used is preferably such that the mineralizer/ammonia molar ratio is in the range of 0.0001 to 0.2. When the molar ratio is 0.0001 or more, it is advantageous from the viewpoint of improving the solubility of the raw material and increasing the growth rate. When the molar ratio is 0.2 or less, it is advantageous from the viewpoint of reducing the level of impurity incorporation. The mineralizer/ammonia molar ratio is more preferably in the range of 0.001 to 0.1, and further preferably in the range of 0.005 to 0.05.

The ammonia filling amount is adjusted so that the pressure in the autoclave used is 40 MPa to 250 MPa at the selected temperature. If the amount of ammonia is increased, the single crystal can be grown more rapidly, but when the pressure exceeds the upper limit of the above range, the valve of the autoclave is operated to discharge a part of the ammonia so as not to exceed the above pressure range.

The pressure in the autoclave during the growth of the single crystal is preferably higher in view of the fact that the growth rate of the single crystal is increased. In the ammoniacal method, the pressure in the autoclave is usually from 20 MPa to 500 MPa, but from the viewpoint of a faster growth rate of the single crystal, it is preferably 30 MPa or more, more preferably 40 MPa or more, and further preferably. It is 50 MPa or more, particularly preferably 60 MPa or more, and most preferably 70 MPa or more. On the other hand, in consideration of the load of the autoclave to be used and the production efficiency of the large-capacity autoclave, the pressure in the autoclave is preferably 250 MPa or less, more preferably 200 MPa or less, and further preferably 150 MPa. Hereinafter, it is especially preferably 130 MPa or less.

The pressure in the autoclave used in the present invention is a specific temperature at a single crystal growth site prescribed by the present invention from the viewpoint of a relatively fast growth rate of a single crystal, a low load on the autoclave, and a good production efficiency. Within the range, it is set in the range of 40 MPa to 250 MPa. The pressure in the autoclave is preferably from 40 MPa to 200 MPa, more preferably from 50 MPa to 180 MPa, and still more preferably from 60 MPa to 150 MPa.

The raw material may be in any shape such as a block, a granule or a powder. Preferably, the material is disposed in a container provided with a plurality of holes or slit-like gaps. The container provided with a plurality of holes may be, for example, a cage container formed of a mesh. The container as described above is used, whereby the raw material can be disposed at a desired position in the autoclave. Regarding the gap of the container or the slit-like gap, the size of the preferred hole or slit, the thickness of the mesh, and the like may be selected depending on the shape of the material to be used. Preferably, the material placed in the container is effectively contacted with the ammonia solvent and rapidly dissolved.

In the method for producing a nitride single crystal of the present invention using the ammonothermal method, it is important to efficiently dissolve the raw material in the supercritical ammonia. Therefore, it is preferred that the flow of the supercritical ammonia as a solvent does not remain in the inside of the autoclave to be used, and the container in which the raw material is placed is placed (especially, a plurality of holes or slits are usually provided as described above). There is a gap of 1 mm or more between the side of the container of the gap and the inner wall of the autoclave.

In the present invention, the temperature (T1) of the single crystal growth portion is 600 ° C or higher, preferably 630 ° C or higher, more preferably 650 ° C or higher, and further preferably 670 ° C from the viewpoint of sufficiently ensuring the crystal growth rate. Above, it is preferably 690 ° C or more. On the other hand, from the viewpoint of durability of the autoclave, the temperature at the single crystal growth site is 850 ° C or lower, preferably 800 ° C or lower, more preferably 750 ° C or lower.

In the method for producing a nitride single crystal according to the present invention, when the temperature in the ammonia gas atmosphere is 600 ° C or higher, the crystal growth rate tends to increase, which is preferable. Up to around 750 ° C, the higher the temperature, the higher the tendency of the crystal growth rate to increase, but the above tendency is reduced at a temperature higher than the vicinity of 750 ° C. Therefore, even if the temperature of the ammonia gas atmosphere is raised to 850 ° C, crystal growth occurs. However, considering the durability of the autoclave, the temperature of the ammonia gas atmosphere is preferably 800 ° C or lower, more preferably 750 ° C or lower.

In the present invention, the temperature (T1) of the crystal growth portion is set to be higher than the temperature (T2) of the material supply portion. That is, the temperature satisfies the relationship of T1>T2. Further, the temperatures T1 and T2 are the average temperatures across the entire crystal growth time. The temperature (T1) of the growth region of the single crystal is a portion where the seed crystal is disposed (in the case of using a seed crystal) or a portion where the nitride single crystal is precipitated and grown by spontaneous nucleation (in the case where the seed crystal is not used). For example, the temperature difference (T1-T2) between the temperature (T1) of the single crystal growth portion and the temperature (T2) of the material supply portion can be set to 1 ° C to 150 ° C. If the temperature difference is increased, the growth rate of crystallization can be increased. On the other hand, if the temperature difference is made small, the single crystal quality tends to be improved. Therefore, the temperature difference (T1-T2) is preferably from 5 ° C to 100 ° C, more preferably from 10 ° C to 90 ° C from the viewpoint of the growth rate of the single crystal (that is, the deposition rate of the single crystal) and the quality of the single crystal.

In the present invention, as long as the above temperature conditions are satisfied, the single crystal growth site may be mixed in the raw material supply portion. For example, if the space for growing the single crystal on the surface is maintained, and the seed crystal and the raw material are placed together in a grid-like container, the nitride single crystal can be grown in a place very close to the place where the raw material is placed, thereby A large crystal growth rate can be achieved.

In the present invention, a vertical autoclave can be used. Fig. 1 is a view showing a state in which a seed crystal is grown in a vertical autoclave to grow a single crystal in the present invention. Fig. 2 is a view showing a state in which a single crystal is grown by spontaneous nucleation in a vertical autoclave in the present invention. In the vertical autoclaves 1 and 2, the pressure gauges 101 and 201 and the valves 102 and 202 are connected to the bodies 103 and 203 via the conduits 104 and 204. In the main bodies 103 and 203, raw material supply portions 109 and 209 and single crystal growth portions 110 and 210 in which the raw materials 106 and 206 accommodated in the raw material containers 105 and 205 are disposed are provided. The bodies 103, 203 are heated by heaters 108, 208. In the autoclave shown in Fig. 1, a seed crystal 107 is disposed at the single crystal growth portion 110. On the other hand, in the autoclave shown in FIG. 2, a single crystal growth site 210 for depositing and growing a Ga-containing nitride single crystal by spontaneous nucleation is disposed in the single crystal growth site 210. There is a board 207. The plate 207 is a plate containing corrosion resistance of one or more holes, and is made of, for example, a mesh material.

In the case of using a vertical autoclave, as shown in FIGS. 1 and 2, it is preferable to arrange the raw material supply portions 109 and 209 at a position higher than the single crystal growth portions 110 and 210 (that is, to observe in the vertical direction). When, the higher position). Thereby, the single crystal can be effectively precipitated. According to such a positional relationship, the single crystal growth portions 110 and 210 can be provided between the raw material supply portions 109 and 209 and the inner bottom surfaces 111 and 211 of the autoclave. In this case, the raw materials fall from the raw material supply portions 109 and 209 to the single crystal growth portions 110 and 210 by gravity, and convection is likely to occur. Further, based on the single crystal generated by spontaneous nucleation in the seed crystal 107 disposed in the single crystal growth site 110 or the single crystal growth site 210, the single crystal can be efficiently grown in the single crystal growth region.

According to the crystal growth method using a vertical autoclave, crystal growth can be efficiently performed by the above-described effect of convection. However, even in the case where the vertical autoclave is not used, and when the vertical autoclave is used and the raw material supply portion is disposed at a position lower than the single crystal growth portion, the convection phenomenon can be produced as long as the convection phenomenon occurs. Single crystal.

In the present invention, it is preferred that the raw material supply portion exists at a position of 10 mm or more from the inner bottom surface of the autoclave (that is, the shortest distance between the inner bottom surface of the autoclave and the raw material supply portion is 10 mm or more), and the raw material is used. A single crystal growth portion exists between the supply portion and the inner bottom surface of the autoclave. In this case, it is possible to effectively prevent the precipitated single crystal from being combined with other single crystal grains to cause polycrystallization. The height from the bottom surface of the autoclave to the raw material supply portion (that is, the shortest distance between the inner bottom surface of the autoclave and the raw material supply portion) can be, for example, 50 mm. Since the single crystal growth portion and the raw material supply portion are provided in the vertical autoclave, the sum of the volume occupied by the single crystal growth portion and the raw material supply portion does not exceed the volume of the entire space in the autoclave, but the ratio can be arbitrarily determined. . In view of productivity, it is preferable to increase the growth point of the single crystal by arranging as many seed crystals as possible or by spontaneously nucleating in a region as wide as possible, but it is necessary to further increase A large amount of raw materials, and therefore it is preferred to also increase the raw material supply site. When the height from the inner surface of the autoclave to the raw material supply portion is 10 mm or more, the space is a single crystal growth portion, whereby the single crystal growth can be efficiently performed in the space. In the case of a vertical autoclave having an internal length of 250 mm, it corresponds to 4% by volume of the entire space in the autoclave. On the other hand, for the above reasons, the volume occupied by the single crystal growth site in the entire space in the autoclave is limited by the size of the raw material supply portion, and typically 70% by volume is the upper limit. It is preferably 10 to 60% by volume, more preferably 20 to 40% by volume.

An important feature of the present invention is that the temperature (T1) of the grown portion of the single crystal is set to 600 ° C to 850 ° C using an acidic mineralizer, and the temperature (T1) of the crystal growth portion is higher than the temperature of the material supply portion (T2). ). In one aspect of the invention, the raw material supply portion is disposed on the upper portion of the autoclave, and the single crystal growth portion is disposed on the lower portion to grow the single crystal. In the conventional configuration in the prior art using an acidic mineralizer (that is, a polycrystalline raw material is disposed in the lower portion of the autoclave and a seed crystal is disposed on the upper portion, and the temperature of the polycrystalline raw material is higher than the temperature of the seed crystal) In the temperature region of the single crystal growth site disclosed in the present invention, that is, 600 to 850 ° C, the nitride single crystal cannot be grown satisfactorily. In addition, the autoclave which is suitable for the implementation of the method of the present invention is an autoclave in which a portion of the shield portion which is a portion which maintains the pressure in the autoclave by closely bonding two or more members constituting the autoclave is The ratio of bismuth to platinum alloy or bismuth monomer and the constituent elements of the material of the shield portion is 20% by mass to 100% by mass. A typical aspect of such an autoclave will be further described in the following <Autoclave>.

As the seed crystal used in one aspect of the present invention, it is preferred to select a material having a parameter of a crystal system, a lattice constant, and a crystal lattice size which are identical or suitable for the target nitride single crystal. For example, when the Ga-containing nitride single crystal produced in the present invention is a GaN single crystal, a nitride single crystal such as aluminum nitride, a single crystal of zinc oxide, and a single crystal of tantalum carbide or the like can be used. More preferably, a single crystal of gallium nitride is used. The method for producing the seed crystal is not particularly limited. For example, in the case of gallium nitride, a single crystal substrate by MOCVD (Metal-Organic Chemical Vapor Deposition) method or HVPE method may be used. The template substrate, a separate substrate obtained by a high pressure method, or an independent GaN crystal produced by a flux method. The nitride single crystal grains obtained by spontaneous nucleation in the ammonothermal method may be used as they are, or may be used after being cut. When the single crystal obtained by spontaneous nucleation has a particle diameter of 1 mm or more, it can be used as a seed crystal. Thereby, as disclosed in the present invention, crystal grains having a size of 1 mm or more can be produced by spontaneous nucleation without using a seed crystal, and the crystal grains can be used as a seed crystal. The crystal granules formed by spontaneous nucleation are used as seed crystals because of their high crystal quality, whereby a high-quality single crystal can be obtained.

In the aspect of spontaneous nucleation of the present invention, in order to obtain a high-quality nitride single crystal, it is preferable to prevent as much as possible the combination of the precipitated single crystal grains and other single crystal grains. Crystallization. The crystal grains which fall to the bottom surface of the autoclave are combined to be easily polycrystallized. Thereby, it is effective to selectively capture a single crystal grain which falls to a certain extent and to grow a single crystal at a capture site. Therefore, it is preferable to arrange a plate having corrosion resistance of one or more holes (for example, the plate 207 shown in Fig. 2) in the single crystal growth portion. The plate may be composed of a mesh material or the like. By arranging such a plate, the single crystal grains captured on the board grow to a larger single crystal.

Further, the above single crystal grains may also be used as a seed crystal in a state in which the seed crystal of the present invention is used. In this case, for example, a single crystal grain is produced by spontaneous nucleation in the state as shown in Fig. 2, and is used as, for example, the seed crystal 107 shown in Fig. 1.

In the present invention, it is preferable to arrange at least one interval between the raw material supply portion and the single crystal growth portion for the purpose of appropriately suppressing convection and maintaining the respective environments of the raw material supply portion and the single crystal growth portion in a preferable state. The board acts as a baffle.

The method for producing a nitride single crystal of the present invention has been described above. The present invention relates to a method of producing a single crystal of a nitride containing Ga. Among the Mg-containing nitride single crystals, the effect obtained by the method disclosed in the present invention, that is, the effect of achieving a faster crystal growth rate and an excellent crystal quality of the obtained single crystal is particularly remarkable. However, it is understood that the manufacturing method of the present invention can be applied to the production of a nitride-containing 13-element nitride single crystal in addition to the production of a Ga-containing nitride. Examples of the group 13 element include, in addition to Ga, B, Al, In, and the like. Examples of the nitride crystal of the group 13 element include, in addition to GaN, BN, AlN, InN, and the like.

<Substrate>

Another aspect of the invention provides a substrate comprising a nitride single crystal produced by the method of the invention described above. The substrate provided by the present invention has excellent crystal quality, and can be preferably used, for example, in a light-emitting element such as a light-emitting diode or a laser diode.

<nitride single crystal>

According to still another aspect of the present invention, a nitride single crystal manufactured by the method of the present invention and having a maximum size of 1 mm or more is provided. Specific examples of the nitride single crystal include, as described above, GaN; a mixed crystal of GaN and other Group 13 element nitrides; and a polynitride containing Ga and other Group 13 elements. A nitride single crystal having a maximum size of 1 mm or more can be preferably used, for example, for a light-emitting element such as a light-emitting diode or a laser diode.

<Autoclave>

Another aspect of the present invention provides an autoclave for use in the method for producing a nitride single crystal according to the present invention, wherein the pressure in the autoclave is maintained by closely bonding two or more parts constituting the autoclave. The material of the shield portion is an alloy of bismuth and platinum or a bismuth monomer, and the proportion of the constituent elements of the material of the shield portion is 20% by mass to 100% by mass.

The inventors of the present invention have discussed a method of producing a Group 13 element nitrogen compound such as GaN or AlN which is expected to be used as a material of a compound semiconductor substrate by an ammoniacal method which is expected to be industrially produced. The inventors of the present invention also discussed the durability of the autoclave with a precious metal lining in the repeated use. Further, it has been found that the autoclave having the constitution described in detail below can be preferably applied to the above-described method for producing a nitride single crystal of the present invention. Furthermore, it has been found that the autoclave provided by the present invention can be sufficiently applied to ammonia using an alkaline mineralizer or a substantially neutral mineralizer in addition to the ammoniacal method using the acidic mineralizer of the present invention. Thermal method. Hereinafter, typical aspects of the autoclave provided by the present invention will be described in detail.

In order to prevent the elution of constituent materials from autoclaves such as iron, nickel, chromium, cobalt, molybdenum, titanium, aluminum, etc., in order to prevent the elution of materials such as iron, nickel, chromium, cobalt, molybdenum, titanium, and aluminum from the autoclave, in order to use a nitride of a group 13 element such as GaN or AlN, the use of the semiconductor substrate has been carried out. An autoclave lined with a precious metal such as platinum. However, since the noble metal such as platinum is a relatively soft material, the body of the autoclave and the shield portion of the lid portion are easily worn. The term "shield portion" refers to a portion that maintains the pressure in the autoclave by closely bonding two or more components constituting the autoclave. That is, the ammonia solvent is brought into contact with the shield portion. As the autoclave is repeatedly used, the solvent leaks out of the wear portion of the shield portion and the pressure cannot be maintained, so that it cannot be used repeatedly. Further, when a noble metal such as platinum is directly used for the shield portion and held at a high temperature of 500 ° C or higher, the shield portion is fixed and the lid cannot be opened. When the shield is fixed, if it is forcibly opened, the shield may be broken and the autoclave may not be used.

The present inventors have conducted various discussions on an autoclave with a precious metal lining which can be used repeatedly in the ammoniacal method. As a result, it was found that as a shield material which does not cause corrosion, abrasion, and melting due to corrosion, abrasion, and melting in an ammonia gas atmosphere containing an acidic mineralizer at a temperature of 400 ° C to 850 ° C and a pressure of 40 MPa to 250 MPa, Suitable are alloys of ruthenium and platinum or ruthenium monomers.

As a material for the lining of the autoclave used in the ammonothermal method, platinum, ruthenium, tungsten, and rhenium are excellent from the viewpoint of preventing corrosion by ammonia. On the other hand, platinum is excellent in terms of the adhesion to the inner surface of the autoclave and the followability of the inner structural lining of the autoclave. However, platinum lining has the problems described below.

The shield portion of the autoclave is configured such that the lid portion is pressed against the autoclave body, and the ammonia is prevented from leaking even under high pressure. Thereby, abrasion and scratches occur in a material having a low hardness such as platinum, so that the autoclave cannot be used repeatedly. The reason is considered to be that the hardness of platinum, for example, Vickers hardness is about 40, which is softer than the metal material constituting the autoclave.

In the present invention, as the material of the shield portion of the autoclave, an alloy of ruthenium and platinum or a ruthenium monomer is used, and the proportion of the constituent elements of the material is 20% by mass to 100% by mass. The Vickers hardness is about 220, which is more than 5 times that of platinum. If the ratio of the content of bismuth is reduced in the alloy of bismuth and platinum, the hardness tends to decrease. However, even if the alloy contains 20% by mass of the alloy, it is a material having a Vickers hardness of about 120 and being very hard compared to the platinum monomer. Therefore, the alloy of ruthenium and platinum or the ruthenium system is more resistant to abrasion and the like than platinum, and is remarkably advantageous for realizing an autoclave including a shield portion having high durability for repeated use.

If the content ratio of the crucible is 20% by mass or more, the hardness of the material is remarkably higher than that of platinum, and it is difficult to cause abrasion due to abrasion and heat. The higher the content ratio of bismuth, the higher the hardness, and the more difficult it is to cause abrasion and heat fusion. In the present invention, the material of the shield portion having the rhodium content ratio within the above range is used, whereby the durability of the autoclave can be changed when the autoclave is repeatedly used in the production of the Mg-containing nitride single crystal by the ammonothermal method. Very good. The content ratio of the barrier material is preferably 40% by mass to 100% by mass, and more preferably 60% by mass to 100% by mass.

Further, the composition of the material of the shield portion and the material of the liner other than the shield portion can be quantified by, for example, X-ray Fluorescence Analysis (XRF). As a method of higher correctness, for example, an inductively-coupled plasma-Atomic Emission Spectrometer (ICP-AES) can be used by dissolving a material in aqua regia or the like. The method, or the method of directly determining the composition via the separation and purification steps of the material.

Further, in the prior art autoclave using a platinum shielding material, the lid portion is pressed against the shield portion, for example, the body to seal it. Thereby, at a high temperature of 500 ° C or higher, the shield portion is melted and adhered (fused), and when the lid is opened, the platinum shield material is peeled off or broken and cannot be used repeatedly. However, the autoclave of the present invention is formed of a shield portion of an alloy of tantalum and platinum or a tantalum monomer, whereby the hardness of the shield portion is very higher than that of the previous shield portion. Thereby, even if a force is applied to the shield portion, abrasion and scratches do not occur, and the autoclave can be used repeatedly.

Further, when the alloy of ruthenium and platinum or the ruthenium monomer is used for the material of the shield portion, the shield portion is not melted and adhered (welded) at a temperature of 850 ° C or lower, and the shield material is not opened even if the lid is opened. Stripped or broken, so it can be used repeatedly.

The autoclave of the present invention is selected from those which can withstand the high temperature and high pressure conditions at the time of crystal growth. The autoclave of the present invention is composed of a material having pressure resistance and corrosion resistance. As a material having pressure resistance and corrosion resistance, a Ni-based alloy is preferable, and the strength characteristics at a high temperature are excellent. Particularly preferred are Inconel 625 (registered trademark of Inconel, The International Nickel Company, Inc.), Rene 41 (registered trademark of Rene Alvac Metals Company), and Udimet 520 (registered trademark of Udimet Specialty Metals, Inc.).

In order to improve the corrosion resistance of the autoclave, it is preferred to lining the noble metal or coating the inner surface of the autoclave with a portion other than the shield portion in contact with ammonia. In the ammoniacal method using an acidic mineralizer, even when the pressure is lower than the case of using an alkaline mineralizer typified by an alkali metal ruthenium or the like, the single crystal is easily grown. Further, since the acidic mineralizer has low corrosiveness to a noble metal such as platinum, the inner surface of the autoclave is lined with a noble metal, whereby the influence of impurities caused by the autoclave can be suppressed to an extremely low level. Examples of the noble metal include platinum (Pt), gold (Au), iridium (Ir), ruthenium (Ru), rhodium (Rh), palladium (Pd), rhodium (Re), and silver (Ag), and these elements are The alloy of the main component. Among them, platinum, rhodium or these alloys are preferred from the viewpoint of excellent corrosion resistance. In particular, since platinum is relatively soft and can follow the shape of the inside of the autoclave, it is particularly preferable as a lining material. When using an alloy of tantalum and platinum or a tantalum monomer as the material of the shield and using platinum as a lining material other than the shield, the shield and the platinum lining material may be welded without a gap, and the welded portion after welding The intensity is also sufficiently high. Autoclaves of this type are particularly advantageous.

Further, in the case where the shield portion of the autoclave is used in close contact with the lining portion other than the shield portion, it is preferable to bond the shield portion of the autoclave to the lining portion other than the shield portion.

The shielding method of the shielding portion is not particularly limited, and may be, for example, a conical sealing method, a gasketing method, or a high-pressure self-tightening method. For the repeated use of the autoclave, it is necessary to prevent the wear and fusion of the shield material in any of the sealing modes. In the autoclave of the present invention, the specific shielding material is used in any of the above-described shielding methods, whereby the durability of the autoclave when it is used repeatedly is very good.

Fig. 3 is a schematic cross-sectional view showing an autoclave of the present invention, and Fig. 4 is a schematic cross-sectional view showing a shield portion of the autoclave of the present invention. The apparatus of the autoclave-type conical sealing type shown in FIG. 3 and FIG. 4 is comprised so that it may seal by the main-body main-body part 301 and the conical cover part 303. The conical cover portion 303, the cushion wrapper 306, and the outer cover portion 305 are placed on the main body portion 301, and the main body portion 301 and the outer cover portion 305 are fixed by the screw fixing portion 307, thereby sealing the autoclave. A body main body shield portion 302 is formed in the main body portion 301, and a conical cover shield portion 304 is formed in the conical cover portion 303. The temperature of the inner tube 309 containing the contents is managed by thermocouples 308A, 308B. In the example shown in Fig. 3, the thermocouple 308A is inserted into the autoclave at a position in the height direction H _A (for example, 15 mm) from the bottom of the inner cylinder 309, and the temperature of the lower portion of the autoclave is measured. Further, a thermocouple 308B is inserted into the autoclave from the bottom of the inner cylinder 309 at a position in the height direction H _B (for example, 150 mm), and the temperature of the upper portion of the autoclave is measured. The inner cylinder 309 is connected to the upper pipe by the connection L via the duct 310.

In the autoclave of the conical shield type, for example, the angle ? formed by the main body shield portion 302 is substantially the same as the angle ? formed by the conical cover shield portion 304, whereby the autoclave can be well sealed. For example, the process of setting the angle α to 60° and the angle β to 59° is preferable, and the angle β is slightly smaller than the angle α. In this case, the sealing becomes better.

Fig. 5 is a schematic view showing an example of piping connected to the upper portion of the autoclave of the present invention. The upper piping shown in Fig. 5 is connected from the autoclave by the connection L via the conduit 310. The duct 310 is divided into a pipe 502 and a pipe 505 via a three-way joint 501. To the pipe 502, a solvent (i.e., ammonia), a substitution gas (for example, nitrogen), and the like are supplied from the pipe 504 via the manual valve 503. The pipe 505 is divided into a pipe 507 and a pipe 509 via a three-way joint 506. The piping 507 reaches the pressure sensor 508. The pipe 509 is passed through the automatic valve 510 to the pipe 511. The pipe 511 is in communication with the outside air. Thereby, when the pressure sensor 508 detects a pressure value exceeding a predetermined value, the automatic valve 510 is opened to prevent the pressure in the autoclave from excessively rising.

For example, in the case of the autoclave of the conical sealing type shown in FIG. 3 and FIG. 4, the "shield portion" means the main body main body shield portion 302 on the main body portion side and the conical cover shield portion 304 on the conical cover portion side. By. In this case, the material of the shield portion of the two layers is an alloy of bismuth with platinum or a bismuth monomer, and the proportion of the constituent elements of the material is 20% by mass to 100% by mass.

The thickness of the shield portion of the autoclave can prevent corrosion of the shield portion caused by high temperature and high pressure ammonia, and can prevent the thickness of the shield portion from being worn, broken, and welded by heat. Specifically, the thickness of the shield portion is preferably from 0.1 mm to 30 mm, more preferably from 0.3 mm to 20 mm, and still more preferably from 0.5 mm to 10 mm. When the shield portion is 0.1 mm or more, the shield portion is hard to be peeled off, and it is difficult to cause cracks due to scratches. On the other hand, since the material of the shield portion is a high-priced precious metal material, the thickness of 30 mm or less is advantageous in terms of cost.

The autoclave of the present invention is particularly useful in an ammoniacal process using an acidic mineralizer. However, it can also be applied to the ammoniacal method using an alkaline mineralizer or a substantially neutral metal salt mineralizer instead of an acidic mineralizer. The acidic mineralizer, the alkaline mineralizer or the substantially neutral metal salt mineralizer has a function of dissolving in an ammonia solvent and promoting dissolution of a nitrogen compound as a raw material. For example, as the alkaline mineralizer, a mineralizer containing an alkali metal element can be cited. More specific examples of the alkaline mineralizer include alkali metal guanamines such as NaNH ₂ , KNH ₂ and LiNH ₂ . Examples of the substantially neutral metal salt mineralizing agent include magnesium halides such as MgCl ₂ and MgBr ₂ , calcium halides such as CaCl ₂ and BaBr ₂ , and halogenated alkali metals such as NaCl, NaBr, KCl, KBr, CsCl, CsBr, LiCl, and LiBr. Compound.

The production system of the Ga-containing nitride single crystal using the autoclave of the present invention can be carried out, for example, in the following order. First, a mineralizer is placed in the autoclave; and a material selected from at least one selected from the group consisting of Ga-containing nitride polycrystals, Ga-containing nitrides, and Ga-containing nitride precursors; It is necessary to add an oxygen scavenging additive, introduce a solvent into the ammonia in the autoclave, and seal the autoclave. Before introducing ammonia into the autoclave, it is preferred to degas the inside of the autoclave and maintain a vacuum to remove oxygen and moisture. When introducing ammonia into the autoclave, it is preferred to cool the autoclave to below the boiling point of ammonia. The reason for this is that in this case, since the vapor pressure of ammonia is low, it is easy to seal the autoclave.

Next, the target single crystal is grown from the raw material at a temperature and pressure set to a desired range. More specifically, the temperature (T1) of the single crystal growth portion is set to 600 ° C to 850 ° C, and the relationship between the temperature (T1) of the single crystal growth portion and the temperature (T2) of the material supply portion is set to TT > T2. And setting the pressure in the autoclave to 40 MPa to 250 MPa, so that the Ga-containing nitride single crystal is contained from a nitride precursor containing a polycrystal containing Ga, a nitride containing Ga, and a nitride containing Ga The raw material of at least one of the group formed grows.

The autoclave of the present invention is particularly useful for the above-described method for producing a Ga-containing nitride single crystal of the present invention. However, the autoclave of the present invention can also be applied to the manufacture of other Group 13 element nitride single crystals. In this case, the raw material containing the group 13 element can be used to grow the single crystal by the method according to the above procedure.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples and comparative examples. The materials, the amounts, the ratios, the treatment contents, and the treatment procedures shown in the following examples can be appropriately changed within the scope of the invention. Therefore, the scope of the invention is not limited by the following examples.

Furthermore, since the measurement of the internal temperature of the autoclave in the supercritical state is extremely difficult, the cover of the empty autoclave is opened, the heater is placed in the state where the valve is removed, and the heating is controlled under the same conditions as in the reaction. The temperature of each part of the inner wall of the autoclave at this time was measured using a thermocouple inserted through a catheter. This temperature value was set to the internal temperature of the autoclave in a supercritical state.

Regarding the configuration shown in the table, "opposite" and "normal" mean the following, respectively.

On the contrary: the raw material supply portion is disposed at a higher position than the single crystal growth portion when viewed in the vertical direction.

Usually: the raw material supply portion is located at a lower position than the single crystal growth portion when viewed in the vertical direction.

[Examples 1 to 7 and Comparative Examples 1 to 8]

Examples 1 to 7 and Comparative Examples 1 to 8 are examples in which single crystal growth of seed crystals was used.

(Example 1)

A single crystal grain of GaN is produced by an ammoniacal method using GaN polycrystals produced by a vapor phase method as a raw material. A GaN single crystal fabricated by spontaneous nucleation is self-shaped to a particle having a length of 4 mm and a thickness of about 0.7 mm as a seed crystal. In the autoclave, a platinum lining is applied to the inner surface other than the shield portion, and the inner surface of the shield portion is made of a platinum alloy (an alloy of ruthenium and platinum and a ruthenium content ratio of 20% by mass), and RENE41 is used as a material. Into the vertical autoclave (inner inch diameter 8 mm, length 250 mm, internal volume of about 12.5 mL). The seed crystal system is fixed by a platinum wire and suspended at a height of about 25 mm from the inner bottom surface of the autoclave.

A cylindrical container made of a GaN polycrystal (about 1 mm to 5 mm) manufactured by a vapor phase method and placed in a platinum plate having a thickness of 0.3 mm (outer dimensions are 5.5 mm in diameter and The height is 100 mm, and 6 slits with a width of 0.5 mm × length of 80 mm are formed on the side and 5 holes with a diameter of 0.5 mm are formed on the bottom surface). The cylindrical container is filled with the filled polycrystal. In the autoclave in which the seed crystal was placed, the cylindrical container was placed so as to maintain a gap of 50 mm from the height of the inner bottom surface of the autoclave.

Next, 0.426 g of ammonium chloride having a purity of 99.99% by mass was placed, and the lid of the autoclave was closed. The container is connected to a vacuum pump to vent the inside. The gas is pumped using a turbo molecular pump until the pressure immediately above the pump reaches 1.0 × 10 ^-4 Pa or less. Thereafter, the autoclave was cooled using dry ice and a refrigerant, and 5.0 g of ammonia having a purity of 99.999 mass% was filled in such a manner that the contents of the autoclave were not brought into contact with external air, and the valve was closed. The amount of ammonia to be filled was converted based on the ammonia density at -33 ° C, which corresponds to 59% by volume of the internal volume of the autoclave.

Next, the autoclave was placed in a heater to heat the autoclave. The average temperature of the polycrystalline arrangement portion (raw material supply portion) was maintained at 656 ° C (at the measurement positions at equal intervals, 681 ° C, 663 ° C, 645 ° C, 646 ° C, and 644 ° C), and then the growth point of the single crystal was The average temperature was maintained at 697 ° C (698 ° C, 699 ° C and 694 ° C at equally spaced measurement positions). At this time, the pressure in the autoclave was 125 MPa.

After maintaining for 168 hours in this state, natural cooling was performed to discharge the internal ammonia. Fig. 6 is a view showing an optical micrograph of a crystal grain (upper) having a size equal to that of the seed crystal used in the first embodiment and a nitride single crystal (bottom) obtained by growing in the first embodiment. As shown in Fig. 6, in Example 1, good crystal growth was confirmed. The seed crystal grows from the original shape to a length of 6.1 mm and a thickness of 1.1 mm. If the single crystal growth rate at this time is estimated, it is 300 μm/day in the longitudinal direction and 57 μm/day in the thickness direction.

The obtained single crystal was placed on a Si-free reflecting plate and subjected to X-ray diffraction measurement. As a result, diffraction derived only from the m-plane was obtained, and it was shown that it was a single crystal.

It was confirmed by X-ray diffraction measurement that the longitudinal direction of the obtained single crystal was the c-axis. The X-ray rocking curve was measured for the diffraction peak from the GaN (0002) plane, and the half-width value was evaluated. As a result, it was 28 arcsec, and it was confirmed that it was high-quality crystal.

(Example 2)

The amount of ammonia to be filled was set to 4.2 g, and the filling amount was set to about 50% by volume based on the density of -33 ° C, and the amount of ammonium chloride was reduced to 0.357 g to extend the reaction time (480 hours). Except for this, the growth of the single crystal was carried out under the same arrangement and temperature conditions as in Example 1. According to the above ammonia filling amount, the pressure in the autoclave at the time of crystal growth was 70 MPa. After 480 hours, the natural cooling was carried out to remove the internal ammonia. The seed crystal system grew from the original state to a length of 7.2 mm and a thickness of 1.7 mm. If the growth rate at this time is estimated, it is 160 μm/day in the longitudinal direction and 50 μm/day in the thickness direction. The obtained single crystal was placed on a Si-free reflecting plate and subjected to X-ray diffraction measurement. As a result, diffraction derived only from the m-plane was obtained, and it was shown that it was a single crystal.

(Example 3)

The crystal grains having a thickness of 1.7 mm obtained in Example 2 were cut perpendicularly in the longitudinal direction to obtain a GaN single crystal substrate having a side (i.e., a length in the m-axis direction) of about 1.5 mm and a thickness of 0.5 mm. This was used as a seed crystal, and the single crystal was grown in accordance with the same configuration, loading, temperature, pressure, and reaction time as in Example 1. The crystal system grows from the original state and grows to a thickness of 0.9 mm and a side of 1.8 mm. When the growth rate at this time is estimated, the thickness direction (c-axis direction) is 57 μm/day, and the opposite direction (m-axis direction) is 43 μm/day.

(Example 4)

A GaN independent substrate (about 5 mm × about 10 mm × thickness about 0.4 mm, weight about 0.15 g) produced by the HVPE method was used as a seed crystal. A platinum plate having a diameter of 2 mm in the center of a circular plate having a diameter of 7 mm is disposed as a partition plate at a height of 50 mm from the bottom surface of the inner surface of the autoclave, and is to be filled. The amount of ammonia was set to 4.3 g, the amount of ammonium chloride was set to 0.365 g, and the holding time (that is, the growth time of the single crystal) was set to 96 hours, except that the same arrangement and temperature conditions as in Example 1 were carried out. Crystal growth. The pressure in the autoclave during crystal growth was 80 MPa.

The seed crystal taken out after growth has grown to a weight of 0.37 g and a thickness of 0.95 mm. If the growth rate in the thickness direction is estimated, it is 135 μm/day.

Regarding the crystal after the growth, an X-ray rocking curve was measured from the diffraction peak of GaN (0002), and the half-width value of the peak was evaluated. As a result, the Ga side was 50 arcsec and the N-face side was 30 arcsec.

(Example 5)

The growth of the single crystal was carried out under the same arrangement, temperature and reaction time as in Example 4 except that the amount of ammonia to be filled was 5.0 g and the amount of ammonium chloride was 0.426 g. The pressure in the autoclave during crystal growth was 125 MPa.

The seed crystal taken out after growth has grown to a weight of 0.45 g and a thickness of 1.1 mm. If the growth rate in the thickness direction is estimated, it is 175 μm/day. With respect to the crystal after the growth, the X-ray rocking curve was measured from the diffraction peak of the GaN (0002) plane, and the half-width value of the peak was evaluated. As a result, the Ga side was 72 arcsec and the N-face side was 137 arcsec.

(Example 6)

Maintaining the average temperature of the polycrystalline portion (ie, the material supply portion) at 702 ° C (725 ° C, 715 ° C, 695 ° C, 690 ° C, and 685 ° C at equally spaced measurement positions), followed by growth of the single crystal The average temperature was maintained at 749 ° C (752 ° C, 749 ° C, and 745 ° C at equally spaced measurement positions), except that the single crystal was carried out under the same loading, arrangement, and reaction time conditions as in Example 5. Growth. The pressure in the autoclave during crystal growth was 140 MPa.

The seed crystal taken out after growth has grown to a weight of 0.47 g and a thickness of 1.15 mm. If the growth rate in the thickness direction is estimated, it is 185 μm/day. With respect to the crystal after the growth, the X-ray rocking curve was measured from the diffraction peak of the GaN (0002) plane, and the half-width value of the peak was evaluated. As a result, the Ga side was 104 arcsec and the N-face side was 61 arcsec.

(Example 7)

The average temperature of the polycrystalline portion was maintained at 610 ° C (615 ° C, 612 ° C, 610 ° C, 608 ° C, and 605 ° C at equally spaced measurement positions), and then the average temperature of the single crystal growth site was maintained at 660. The growth of the single crystal was carried out under the same arrangement, loading, and reaction time conditions as in Example 5 except that °C (662 ° C, 660 ° C, and 658 ° C at the measurement positions at equal intervals). The pressure in the autoclave during crystal growth was 105 MPa.

The seed crystal taken out after growth has grown to a weight of 0.30 g and a thickness of 0.85 mm. If the growth rate in the thickness direction is estimated, it is 110 μm/day. With respect to the crystal after the growth, the X-ray rocking curve was measured from the diffraction peak of the GaN (0002) plane, and the half-width value of the peak was evaluated. As a result, the Ga side was 169 arcsec, and the N-face side was 187 arcsec.

(Comparative Example 1)

The average temperature of the polycrystalline portion was maintained at 638 ° C (620 ° C, 633 ° C, 645 ° C, 650 ° C, and 644 ° C at equally spaced measurement positions), and then the average temperature of the grown portion of the single crystal was maintained at 601. The growth of the single crystal was carried out under the same arrangement and loading conditions as in Example 1 except that the temperature was °C (590 ° C, 602 ° C, and 610 ° C at the measurement positions at equal intervals). The pressure in the autoclave during crystal growth was 96 MPa.

After 168 hours, the natural cooling was carried out, and after the ammonia was discharged, when the inside of the autoclave was confirmed, the seed crystals which were placed were all dissolved and disappeared.

(Comparative Example 2)

The amount of ammonia to be filled was set to 2.5 g, and the amount of ammonia was set to about 30% by volume based on the ammonia density of -33 ° C, and the ammonium chloride as a mineralizer was reduced to 0.213 g. The growth of the single crystal was carried out under the same arrangement, temperature and reaction time as in Example 1. The pressure in the autoclave during crystal growth was 27 MPa. After 168 hours, the natural cooling was carried out, and after the ammonia was discharged, when the inside of the autoclave was confirmed, it was found that the deposited seed crystals and the polycrystalline raw materials remained substantially directly, and no crystal growth was caused.

(Comparative Example 3)

A single crystal grain of GaN is produced by an ammoniacal method using GaN polycrystals produced by a vapor phase method as a raw material. A GaN single crystal fabricated by spontaneous nucleation is self-shaped to a particle having a length of 4 mm and a thickness of about 0.7 mm as a seed crystal. In the autoclave, a platinum lining is applied to the inner surface other than the shield portion, and the inner surface of the shield portion is made of a platinum alloy (an alloy of ruthenium and platinum and a ruthenium content ratio of 20% by mass), and RENE41 is used as a material. Into the vertical autoclave (inner inch diameter 8 mm, length 250 mm and internal volume of about 12.5 mL).

A cylindrical container made of a GaN polycrystal (about 1 mm to 5 mm) manufactured by a vapor phase method and placed in a platinum plate having a thickness of 0.3 mm (outer dimensions are 5.5 mm in diameter and The height is 100 mm, and 6 slits with a width of 0.5 mm × length of 80 mm are formed on the side and 5 holes with a diameter of 0.5 mm are formed on the bottom surface). The cylindrical container is filled with the filled polycrystal. The container was placed in an autoclave, and the container was placed in such a manner that the GaN polycrystal was disposed at a height from 0 mm to about 100 mm from the inner bottom surface of the autoclave.

The seed crystal system was fixed by a platinum wire and placed at a height of 150 mm from the inner bottom surface of the autoclave. Next, 0.426 g of ammonium chloride having a purity of 99.99% by mass was placed, and the lid of the autoclave was closed.

The container is connected to a vacuum pump to vent the inside. The gas is pumped using a turbo molecular pump until the pressure immediately above the pump reaches 1.0 × 10 ^-4 Pa or less. Thereafter, the autoclave was cooled using dry ice and a refrigerant, and 5.0 g of ammonia having a purity of 99.999 mass% was filled in such a manner that the contents of the autoclave were not brought into contact with external air, and the valve was closed. The amount of ammonia to be filled was converted based on the ammonia density at -33 ° C, which corresponds to 59% by volume of the internal volume of the autoclave.

Next, the autoclave was placed in a heater to heat the autoclave. The average temperature of the polycrystalline portion (from 0 to 100 mm from the inner bottom surface of the autoclave) was maintained at 698 ° C (at 708 ° C, 702 ° C, 698 ° C, 695 ° C, and 685 at equally spaced measurement positions). °C), and then the average temperature of the single crystal growth site (the height from the inner bottom surface of the autoclave is 125 to 175 mm) is maintained at 665 ° C (at the measurement position of the equal interval, it is 675 ° C, 670 ° C, 660 ° C, 663 ° C and 658 ° C). At this time, the pressure in the autoclave was 125 MPa.

After maintaining for 96 hours in this state, natural cooling was performed to discharge the internal ammonia. When the inside of the autoclave was confirmed, the seed crystals placed were all dissolved and disappeared.

(Comparative Example 4)

The average temperature of the polycrystalline portion was maintained at 509 ° C (548 ° C, 521 ° C, 500 ° C, 492 ° C, and 485 ° C at equally spaced measurement positions), and then the average temperature of the grown portion of the single crystal was maintained at 581. The growth of the single crystal was carried out under the same arrangement and loading conditions as in Example 1 except that °C (583 ° C, 581 ° C, and 578 ° C at the measurement positions at equal intervals) and the shortening of the crystal growth time. The pressure in the autoclave during crystal growth was 100 MPa. After 96 hours, the natural cooling was carried out to remove the internal ammonia. When the inside of the autoclave was confirmed, the seed crystals placed were all dissolved and disappeared.

(Comparative Example 5)

The average temperature of the polycrystalline portion was maintained at 697 ° C (685 ° C, 698 ° C, 705 ° C, 700 ° C, and 699 ° C at equally spaced measurement positions), and then the average temperature of the grown portion of the single crystal was maintained at 661. The growth of the single crystal was carried out in the same manner as in Example 1 except that the crystal growth time (96 hours) was shortened at ° C (in the measurement position at equal intervals, 658 ° C, 661 ° C, and 664 ° C). The pressure in the autoclave during crystal growth was 125 MPa. After 96 hours of maintenance, the natural cooling was carried out, and after the ammonia was discharged, when the inside of the autoclave was confirmed, the seed crystals which were placed were all dissolved and disappeared.

(Comparative Example 6)

A GaN independent substrate (about 5 mm × about 10 mm × thickness about 0.4 mm, weight about 0.15 g) produced by the HVPE method is used as a seed crystal at a height of about 50 mm from the inner bottom surface of the autoclave to A platinum plate having a hole having a diameter of 2 mm in the center of a circular plate having a diameter of 7 mm was disposed as a partition plate in such a manner that the diameter direction was horizontal, and the amount of ammonia to be filled was set to 5.2 g, and the amount of ammonium chloride was set to The growth of the single crystal was carried out under the same arrangement conditions as in Comparative Example 3 except that 0.443 g and the heating and holding conditions were changed. The average temperature of the polycrystalline portion (from 0 to 100 mm from the bottom surface of the autoclave) was maintained at 554 ° C (at 563 ° C, 562 ° C, 553 ° C, 547 ° C and 544 at equally spaced measurement positions). °C), and then the average temperature of the single crystal growth site (the height from the inner bottom surface of the autoclave is 125 to 175 mm) is maintained at 453 ° C (at the equally spaced measurement positions, 470 ° C, 462 ° C, 450 ° C, 443 ° C and 438 ° C), and maintained for 168 hours. At this time, the pressure in the autoclave was 120 MPa.

The seed crystal taken out after growth has grown to a weight of 0.23 g and a thickness of 0.57 mm. If the growth rate in the thickness direction is estimated, it is 25 μm/day. With respect to the crystal after the growth, the X-ray rocking curve was measured from the diffraction peak of GaN (0002), and the half-width value of the peak was evaluated. As a result, the Ga side was 173 arcsec, and the N-face side was 3420 arcsec.

(Comparative Example 7)

The growth was carried out under the same arrangement and reaction time conditions as in Comparative Example 6, except that the amount of ammonia to be filled was 4.7 g and the amount of ammonium chloride was changed to 0.400 g. The pressure in the autoclave during crystal growth was 90 MPa.

The seed crystal taken out after growth has grown to a weight of 0.17 g and a thickness of 0.43 mm. If the growth rate in the thickness direction is estimated, it is 4.3 μm/day. With respect to the crystal after the growth, the X-ray rocking curve was measured from the diffraction peak of GaN (0002), and the half-width value of the peak was evaluated. As a result, the Ga side was 151 arcsec, and the N-face side was 181 arcsec.

(Comparative Example 8)

A GaN independent substrate (about 5 mm × about 10 mm × thickness about 0.4 mm, weight about 0.15 g) produced by the HVPE method is used as a seed crystal at a height of about 50 mm from the inner bottom surface of the autoclave to A platinum plate having a hole having a diameter of 2 mm in the center of a disk having a diameter of 7 mm was placed as a partition plate in the horizontal direction, and the same arrangement, loading, and pressure as in Comparative Example 3 were used. condition. After 96 hours, the natural cooling was carried out to remove the internal ammonia. When the inside of the autoclave was confirmed, the seed crystals placed were all dissolved and disappeared.

[Examples 8 to 11 and Comparative Examples 9 to 11]

Examples 8 to 11 and Comparative Examples 9 to 11 are examples in which seed crystal growth is not used.

(Example 8)

A cylindrical container made of a GaN polycrystal (about 1 mm to 5 mm) manufactured by a vapor phase method and placed in a platinum plate having a thickness of 0.3 mm (outer dimensions are 5.5 mm in diameter and The height is 100 mm, and 6 slits with a width of 0.5 mm × length of 80 mm are formed on the side and 5 holes with a diameter of 0.5 mm are formed on the bottom surface). The filled polycrystal is in a state of being filled in a cylindrical container. The container filled with the polycrystal is placed on the inner surface other than the shield portion to be platinum-lined and has a platinum-based alloy on the inner surface of the shield portion so as to maintain a gap of 50 mm in the height direction from the inner bottom surface.铱 and platinum alloy and ruthenium content ratio: 20% by mass) A vertical autoclave made of RENE41 as a material (inner size 8 mm in diameter, 250 mm in length and 12.5 mL in internal volume) was placed in the lining.

Next, 0.426 g of ammonium chloride having a purity of 99.99% by mass was placed, and the lid of the autoclave was closed. The container is connected to a vacuum pump to vent the inside. The gas is pumped using a turbo molecular pump until the pressure immediately above the pump reaches 1.0 × 10 ^-4 Pa or less. Thereafter, the autoclave was cooled using dry ice and a refrigerant, and 5.0 g of ammonia having a purity of 99.999 mass% was filled in such a manner that the contents of the autoclave were not brought into contact with external air, and the valve was closed. The amount of ammonia to be filled was converted based on the ammonia density at -33 ° C, which corresponds to 59% by volume of the internal volume of the autoclave.

Next, the autoclave was placed in a heater to heat the autoclave. The average temperature of the polycrystalline portion was maintained at 621 ° C (at 680 ° C, 647 ° C, 610 ° C, 588 ° C, and 580 ° C at equally spaced measurement positions), and then the average temperature of the single crystal growth site was maintained at 715. °C (at 7.3 ° C, 720 ° C and 701 ° C at equally spaced measurement positions). At this time, the pressure in the autoclave was 115 MPa.

After maintaining for 168 hours in this state, natural cooling was performed to discharge the internal ammonia. A single crystal having a length of 1 mm to 5 mm is deposited on the inner wall surface and the bottom surface of the autoclave at the growth site of the single crystal. The weight of the single crystal after washing and drying was 1.5 g. The polycrystal has 3.0 g remaining in a platinum container. The difference of the amount of 0.5 g between the amount of the generated single crystal and the residual polycrystal is considered to be eluted in the washing step, or attached to the inside of the autoclave or the like.

Fig. 7 is a view showing an X-ray diffraction pattern (XRD (Xray Diffraction Measurement) pattern) of the GaN single crystal obtained in Example 8. Fig. 8 is a view showing an optical micrograph of a GaN single crystal obtained in Example 8. As shown in Fig. 7, the obtained crystal grains were confirmed to be hexagonal GaN by X-ray diffraction. Further, one crystal grain of the adjusted form was placed on a Si-free reflecting plate, and X-ray diffraction measurement was performed. As a result, diffraction from only the m-plane was obtained, and it was shown that it was a single crystal. The appearance of the obtained single crystal is as shown in FIG.

(Example 9)

A platinum grid having a mesh of 0.5 mm was placed at a height of 10 mm from the inner bottom surface of the autoclave, except for the same arrangement, loading, temperature, pressure, and reaction time as in Example 8. The growth of single crystals is implemented. After the end of the experiment, it was confirmed that a single crystal having a self-shaped adjustment length of 3 mm to 5 mm was deposited on the grid.

The obtained crystal grains were confirmed to be hexagonal GaN by X-ray diffraction. Further, one crystal grain of the adjusted form was placed on a Si-free reflecting plate, and X-ray diffraction measurement was performed. As a result, diffraction from only the m-plane was obtained, and it was shown that it was a single crystal.

(Embodiment 10)

The amount of ammonia to be filled was set to 4.2 g, and the filling amount was set to about 50% by volume based on the NH ₃ density of -33 ° C, and the amount of ammonium chloride as a mineralizer was reduced to 0.357 g, except Except for this, the growth of the single crystal was carried out under the same arrangement conditions as in Example 1. According to the above ammonia filling amount, the pressure in the autoclave during crystal growth was 70 MPa. After 168 hours, the natural cooling was carried out to remove the internal ammonia. A single crystal having a length of about 0.5 mm to 3 mm is deposited on the inner wall surface and the bottom surface of the autoclave in the growth region of the single crystal, and the weight of the single crystal to be washed and dried is 0.9 g. The polycrystal has 3.5 g remaining in a platinum container. The difference of the amount of the charge and the amount of the generated single crystal and the residual polycrystal of 0.6 g is considered to be eluted in the washing step, or attached to the inside of the autoclave or the like.

The obtained crystal grains were confirmed to be hexagonal GaN by X-ray diffraction. Further, one crystal grain of the adjusted form was placed on a Si-free reflecting plate, and X-ray diffraction measurement was performed. As a result, diffraction from only the m-plane was obtained, and it was shown that it was a single crystal.

(Example 11)

A cylindrical container made of a GaN polycrystal (about 1 mm to 5 mm) manufactured by a vapor phase method and placed in a platinum plate having a thickness of 0.3 mm (outer dimensions are 5.5 mm in diameter and The height is 100 mm, and 6 slits with a width of 0.5 mm × length of 80 mm are formed on the side and 5 holes with a diameter of 0.5 mm are formed on the bottom surface). The filled polycrystal is in a state of being filled in a cylindrical container. The container filled with the polycrystal is placed on the inner surface except the shield portion to be platinum-lined and the inner surface of the shield portion is made of platinum alloy so as to maintain a gap of 50 mm in the height direction from the inner bottom surface. (An alloy of ruthenium and platinum and a ruthenium content of 20% by mass) A vertical autoclave (with a diameter of 8 mm, a length of 250 mm, and an internal volume of about 12.5 mL) made of RENE41 was used as a lining.

Next, 0.426 g of ammonium chloride having a purity of 99.99% by mass was placed, and the lid of the autoclave was closed. The container is connected to a vacuum pump to vent the inside. The gas is pumped using a turbo molecular pump until the pressure immediately above the pump reaches 1.0 × 10 ^-4 Pa or less. Thereafter, the autoclave was cooled using dry ice and a refrigerant, and 5.0 g of ammonia having a purity of 99.999 mass% was filled in such a manner that the contents of the autoclave were not brought into contact with external air, and the valve was closed. The amount of ammonia to be filled was converted based on the ammonia density at -33 ° C, which corresponds to 59% by volume of the internal volume of the autoclave.

Next, the autoclave was placed in a heater to heat the autoclave. The average temperature of the polycrystalline portion was maintained at 656 ° C (681 ° C, 663 ° C, 645 ° C, 646 ° C, and 644 ° C at equally spaced measurement positions), and then the average temperature of the single crystal growth site was maintained at 697. °C (698 ° C, 699 ° C and 694 ° C at equally spaced measurement positions). At this time, the pressure in the autoclave was 125 MPa.

After maintaining for 168 hours in this state, natural cooling was performed to discharge the internal ammonia. A single crystal having a length of about 1 mm to 5 mm was deposited on the inner wall surface and the bottom surface of the autoclave in the growth region of the single crystal, and the weight of the single crystal after washing and drying was 1.1 g. The polycrystal has 3.5 g remaining in a platinum container. It is considered that the difference between the amount of the charge and the amount of the generated single crystal and the residual polycrystal is 0.4 g, which flows out in the washing step, or adheres to the inside of the autoclave or the like.

The obtained crystal grains were confirmed to be hexagonal GaN by X-ray diffraction. Further, one crystal grain of the adjusted form was placed on a Si-free reflecting plate, and X-ray diffraction measurement was performed. As a result, diffraction from only the m-plane was obtained, and it was shown that it was a single crystal.

(Comparative Example 9)

A cylindrical container made of a GaN polycrystal (about 1 mm to 5 mm) manufactured by a vapor phase method and placed in a platinum plate having a thickness of 0.3 mm (outer dimensions are 5.5 mm in diameter and The height is 100 mm, and 6 slits with a width of 0.5 mm × length of 80 mm are formed on the side and 5 holes with a diameter of 0.5 mm are formed on the bottom surface). The filled polycrystal is in a state of being filled in a cylindrical container. The container filled with the polycrystal is placed on the inner surface other than the shield portion to be platinum-lined and has a platinum-based alloy on the inner surface of the shield portion so as to maintain a gap of 50 mm in the height direction from the inner bottom surface.铱 and platinum alloy and ruthenium content ratio: 20% by mass) A vertical autoclave made of RENE41 as a material (inner size 8 mm in diameter, 250 mm in length and 12.5 mL in internal volume) was placed in the lining.

Next, 0.426 g of ammonium chloride having a purity of 99.99% by mass was placed, and the lid of the autoclave was closed. The container is connected to a vacuum pump to vent the inside. The gas is pumped using a turbo molecular pump until the pressure immediately above the pump reaches 1.0 × 10 ^-4 Pa or less. Thereafter, the autoclave was cooled using dry ice and a refrigerant, and 5.0 g of ammonia having a purity of 99.999 mass% was filled in such a manner that the contents of the autoclave were not brought into contact with external air, and the valve was closed. The amount of ammonia to be filled was converted based on the ammonia density at -33 ° C, which corresponds to 59% by volume of the internal volume of the autoclave.

Next, the autoclave was placed in a heater to heat the autoclave. The average temperature of the polycrystalline portion was maintained at 638 ° C (620 ° C, 633 ° C, 645 ° C, 650 ° C, and 644 ° C at equally spaced measurement positions), followed by the growth of the single crystal in Example 11. The average temperature at the equivalent position was maintained at 600 ° C (590 ° C, 602 ° C and 610 ° C at equally spaced measurement positions). At this time, the pressure in the autoclave was 96 MPa.

After maintaining for 168 hours in this state, natural cooling was performed to discharge the internal ammonia. No precipitate was observed in the inner wall surface and the bottom surface of the autoclave in the vicinity of the portion corresponding to the single crystal growth site in Example 11. Fine powdery precipitates adhered to the inner wall surface of the autoclave and the vicinity of the upper portion of the autoclave in the vicinity of the polycrystalline arrangement portion, and these were confirmed to be hexagonal GaN by X-ray diffraction. However, since the precipitate has a shape of agglomerated matter, it cannot be separated as a single crystal grain. Observation by a scanning electron microscope revealed that the shape was close to a hexagonal column, but the precipitates were aggregated in a micron size, so that they could not be taken out as a single crystal.

(Comparative Example 10)

The amount of ammonia to be filled was set to 3.0 g, the filling amount was set to about 36% by volume of the container, and the amount of ammonium chloride as a mineralizer was reduced to 0.256 g, in addition to the ammonia density of -33 ° C. The growth of the single crystal was carried out under the same arrangement, temperature and reaction time as in Example 11. According to the above ammonia filling amount, the pressure in the autoclave during crystal growth was 30 MPa. After 168 hours, the natural cooling was carried out to remove the internal ammonia. The polycrystalline raw material remained 4.8 g, and although some amount was dissolved, almost no recyclable precipitate was found inside the autoclave.

(Comparative Example 11)

The experiment was carried out under the same conditions of the arrangement, charging, temperature, pressure and reaction time as in Comparative Example 6, except that the seed crystal of Comparative Example 6 was not used. The single crystal growth site was set to the same position as the single crystal growth site of Comparative Example 6. After 168 hours, fine powder-like precipitates adhered to the inner wall of the autoclave and the upper portion of the autoclave corresponding to the growth site of the single crystal, and these were confirmed to be hexagonal GaN by X-ray diffraction. However, since the precipitate is in the form of agglomerates, it cannot be separated as a single crystal grain.

The results of the above Examples 1 to 11 and Comparative Examples 1 to 11 are shown in Tables 1 to 3 below.

[Examples 12 to 15 and Comparative Examples 12 to 15]

The durability of the autoclave was discussed in Examples 12 to 15 and Comparative Examples 12 to 15.

(Examples 12 to 15)

The GaN single crystal was grown using the autoclave shown in Figs. 3 and 4 . The material of the autoclave is Rene 41 (registered trademark of Rene Alvac Metals Company). As a material of the shield portion of the main body main body shield portion 302 and the conical cover shield portion 304, an alloy of niobium and platinum (a niobium content ratio of 20% by mass) was used. The thickness of the base of the body main body shield portion 302 and the platinum alloy is 11 mm from the side surface of the body main body portion 301 at a position 12 mm or less in the height direction from the upper surface of the main body. Further, the thickness of the conical cover shield portion 304 is 1.0 mm. In the autoclave used, the portion in contact with ammonia other than the shield portion was lined with platinum having a thickness of 0.5 mm. The inner diameter of the autoclave is 8 mm, the length of the inner cylinder is about 204 mm, and the volume is about 10 ml.

At the bottom of the inner tube 309 of the main body portion 301 of the autoclave, 0.19 g of dried NH ₄ Cl powder having a purity of 99.99% by mass was placed as a mineralizer. Next, a platinum mesh was placed at a position 40 mm or more in the height direction from the bottom of the inner face cylinder 309 of the main body portion 301 of the autoclave, and a thickness of 0.4 mm and a length of 10 mm which were produced by the HVPE method were placed thereon. Eight GaN plates of 5 mm in width were used as raw materials for GaN single crystal growth. Next, as shown in FIG. 3, the conical cover portion 303 is placed on the main body portion 301, and the cushion wrapper 306 and the outer cover portion 305 are placed, and the outer cover portion 305 and the main body portion 301 are tightly screwed. Further, the upper pipe shown in Fig. 5 is placed on the upper portion of the conical cover portion 303.

A heater is disposed in such a manner as to cover the entire autoclave. Specifically, the heaters of the upper and lower stages are arranged with the center of the main body of the main body as a boundary. As shown in Fig. 3, the temperature of the lower portion of the autoclave was at a position 15 mm or more in the height direction from the bottom of the inner tube 309 of the main body portion 301, and the thermocouple 308A was inserted into the autoclave for measurement. Further, the temperature of the upper portion of the autoclave was at a position 150 mm or more in the height direction from the bottom of the inner tube 309 of the main body portion 301, and the thermocouple 308B was inserted into the autoclave for measurement.

In this example, the upper pipe shown in Fig. 5 was connected to the autoclave. In a state where the automatic valve 510 is closed, nitrogen is supplied from the pipe 504 through the manual valve 503 to the autoclave, and after the inside of the autoclave is temporarily replaced by nitrogen gas, the vacuum degassing device is connected to the front end of the pipe 504, and the manual valve 503 is opened. The exhaust gas in the autoclave was set to a vacuum. Then, the pipe 504 and the pipe 511 are removed while the manual valve 503 is closed, and the autoclave shown in FIG. 3 is combined with the unloading pipe 504 and the pipe above the pipe 511 to measure the weight. Next, the piping 504 and the piping 511 are placed, and the inside of the autoclave is vacuumed in the same manner, and then cooled from the outside of the main body portion 301 by a dry ice methanol solvent, and the ammonia is interposed from the piping 504 through the manual valve 503. Fill into the autoclave. The ammonia flow rate was measured, and ammonia was filled into the autoclave so that the ammonia amount reached 50% by volume of the volume in the autoclave in a liquid ammonia state of -33 °C. After the ammonia was filled, the manual valve 503 was closed, and the temperature was returned to the room temperature. The piping 504 and the piping 511 were again removed, and the weight of the autoclave with the upper piping was measured to confirm that the ammonia filling amount was suitable.

In order to grow the GaN single crystal by heat treatment in an ammonia gas atmosphere, heating is performed by a heater from the outside of the autoclave, and the temperature of the lower portion and the upper portion of the autoclave is maintained at a temperature higher than the upper portion and the temperature is maintained at a lower portion. The temperature was raised for 12 hours, and it was kept for 24 hours under the predetermined upper stage holding temperature and the lower stage holding temperature shown in Table 4 below, and further cooled to 60 ° C in 12 hours, and further allowed to stand at room temperature. In addition, the pressure in the autoclave during the growth of the GaN single crystal is performed by using the manual valve to escape the pressure so as not to exceed 120 MPa, while maintaining the pressure at a predetermined upper temperature and maintaining the pressure at a lower temperature of 120 MPa. Adjustment.

After confirming that the temperature of the autoclave has reached approximately room temperature, the entire autoclave is removed from the heater, and the outlet side of the pipe 504 is connected to the waste scrubbing exhaust gas for ammonia recovery, and the manual valve 503 is slowly opened to be discharged into the autoclave. ammonia.

In order to completely discharge the ammonia in the autoclave, high-purity nitrogen was injected into the autoclave at a pressure of 0.5 MPa for 10 times, and then the operation of opening the atmosphere was repeated. The ammonia exhaust system is all connected to the waste scrubbing exhaust gas for ammonia recovery and is exhausted. Thereafter, the lid of the autoclave was opened, and the grown GaN single crystal was confirmed inside.

The experimental results of Examples 12 to 15 are shown in Table 4 below.

In any of the examples 12 to 15, a platinum mesh was placed at a position 40 mm or more in the height direction from the bottom of the inner face cylinder 309 of the main body portion 301 of the autoclave, and the thickness was 0.4 mm by the HVPE method. All 8 GaN plates of 10 mm in length and 5 mm in width were dissolved. Further, it was confirmed that a hexagonal columnar GaN single crystal grown on the bottom of the inner surface tube 309 and the inner wall surface of the platinum lining of the main body portion 301 of the autoclave was confirmed.

Fig. 9 is a view showing an optical micrograph of a GaN single crystal obtained in Example 13. In any of Examples 12 to 15, a substantially hexagonal columnar GaN single crystal having a length of approximately 3 mm or less as shown in the optical micrograph of Fig. 9 was obtained. Fig. 10 is a view showing an X-ray diffraction pattern (XRD pattern) of a GaN single crystal obtained in Example 13. From the results shown in Fig. 10, it was confirmed that in the hexagonal GaN obtained in Example 13, the orientation of the m-plane was strong by the self-shape of the crystal grains. Further, in Examples 12, 14 and 15, the same X-ray diffraction measurement results as those shown in Fig. 10 were obtained.

The GaN single crystal growth experiment was repeated, and the number of times of repeated crystal growth durability of the shield portion of the autoclave was measured and shown in Table 4. The basis for the number of times of repeated crystal growth and durability is that the number of times of the GaN crystal growth of the autoclave is maintained at a pressure of 120 MPa without replacing the parts of the autoclave.

As shown in Table 4, when the shielding material in the autoclave of the present invention is used in a high-temperature and high-pressure ammonia atmosphere, the number of times of repeated crystal growth durability is also much higher than that of the following comparative examples, so that the use of the autoclave is improved. Durability.

(Examples 16 to 19)

As a material of the shield portion of the main body shield portion 302 and the conical cover shield portion 304 shown in FIGS. 3 and 4, an alloy containing ruthenium and rhodium in a proportion of 40% by mass is used, and in addition to Examples 12 to 15, In the same way, the growth of GaN single crystals is carried out. The experimental results of Examples 16 to 19 are shown in Table 5 below.

In any of the examples 16 to 19, a platinum mesh was placed at a position 40 mm or more in the height direction from the bottom of the inner face cylinder 309 of the main body portion 301 of the autoclave, and the thickness was 0.4 mm by the HVPE method. All 8 GaN plates of 10 mm in length and 5 mm in width were dissolved. Further, it was confirmed that a hexagonal columnar GaN single crystal grown on the bottom of the inner surface tube 309 and the inner wall surface of the platinum lining of the main body portion 301 of the autoclave was confirmed.

In any of Examples 16 to 19, a substantially hexagonal columnar GaN single crystal having a length of approximately 3 mm or less which is the same as that shown in the optical micrograph of Fig. 9 was obtained. In any of Examples 16 to 19, the same X-ray diffraction measurement results as those shown in Fig. 10 were obtained.

The GaN single crystal growth experiment was repeated, and the number of times of repeated crystal growth durability of the shield portion of the autoclave was measured and shown in Table 5. The basis for the number of times of repeated crystal growth and durability is that the number of times of the GaN crystal growth of the autoclave is maintained at a pressure of 120 MPa without replacing the parts of the autoclave.

As shown in Table 5, when the shielding material in the autoclave of the present invention is used in a high-temperature and high-pressure ammonia atmosphere, the number of times of repeated crystal growth durability is also much higher than that of the following comparative examples, thereby improving the use of the autoclave. Durability.

(Examples 20 to 23)

As the material of the shield portion of the main body main body shield portion 302 and the conical cover shield portion 304 shown in FIGS. 3 and 4, an alloy containing ruthenium and rhodium in an amount of 60% by mass is used, and the examples 12 to 15 are used. In the same way, the growth of GaN single crystals is carried out. The experimental results of Examples 20 to 23 are shown in Table 6 below.

In any of the examples 20 to 23, a platinum mesh was placed at a position 40 mm or more in the height direction from the bottom of the inner face cylinder 309 of the main body portion 301 of the autoclave, and the thickness was 0.4 mm by the HVPE method. All 8 GaN plates of 10 mm in length and 5 mm in width were dissolved. Further, it was confirmed that a hexagonal columnar GaN single crystal grown on the bottom of the inner surface tube 309 and the inner wall surface of the platinum lining of the main body portion 301 of the autoclave was confirmed.

In any of Examples 20 to 23, a substantially hexagonal columnar GaN single crystal having a length of approximately 3 mm or less which is the same as that shown in the optical micrograph of Fig. 9 was obtained. In any of Examples 20 to 23, the same X-ray diffraction measurement results as those shown in Fig. 10 were obtained.

The GaN single crystal growth experiment was repeated, and the number of times of repeated crystal growth durability of the shield portion of the autoclave was measured and shown in Table 6. The basis for the number of times of repeated crystal growth and durability is that the number of times of the GaN crystal growth of the autoclave is maintained at a pressure of 120 MPa without replacing the parts of the autoclave.

As shown in Table 6, when the shielding material in the autoclave of the present invention is used in a high-temperature and high-pressure ammonia atmosphere, the number of times of repeated crystal growth durability is also much higher than that of the following comparative examples, so that the use of the autoclave is improved. Durability.

(Examples 24 to 27)

The material of the shield portion of the main body shield portion 302 and the conical cover shield portion 304 shown in FIG. 3 and FIG. 4 is the same as that of the examples 12 to 15 except that the tantalum material having a niobium content of 100% by mass is used. Method, the growth of GaN single crystal is carried out. The experimental results of Examples 24 to 27 are shown in Table 7 below.

In any of the examples 24 to 27, a platinum mesh was placed at a position 40 mm or more in the height direction from the bottom of the inner face cylinder 309 of the main body portion 301 of the autoclave, and the thickness was 0.4 mm by the HVPE method. All 8 GaN plates of 10 mm in length and 5 mm in width were dissolved. Further, it was confirmed that a hexagonal columnar GaN single crystal grown on the bottom of the inner surface tube 309 and the inner wall surface of the platinum lining of the main body portion 301 of the autoclave was confirmed.

In any of Examples 24 to 27, a substantially hexagonal columnar GaN single crystal having a length of approximately 3 mm or less which is the same as that shown in the optical micrograph of Fig. 9 was obtained. In any of Examples 24 to 27, the same X-ray diffraction measurement results as those shown in Fig. 10 were obtained.

The GaN single crystal growth experiment was repeated, and the number of times of repeated crystal growth durability of the shield portion of the autoclave was measured and shown in Table 7. The basis for the number of times of repeated crystal growth and durability is that the number of times of the GaN crystal growth of the autoclave is maintained at a pressure of 120 MPa without replacing the parts of the autoclave.

As shown in Table 7, when the shielding material in the autoclave of the present invention is used in a high-temperature and high-pressure ammonia atmosphere, the number of times of repeated crystal growth durability is also much higher than that of the following comparative examples, so that the use of the autoclave is improved. Durability.

(Comparative examples 12 to 15)

The material of the shield portion of the main body shield portion 302 and the conical cover shield portion 304 shown in FIG. 3 and FIG. 4 is the same as those of the examples 12 to 15 except that a platinum having a platinum content of 100% by mass is used. Method, the growth of GaN single crystal is carried out. The experimental results of Comparative Examples 12 to 15 are shown in Table 8 below.

In any of Comparative Examples 12 to 15, a platinum mesh was placed at a position 40 mm or more in the height direction from the bottom of the inner face cylinder 309 of the main body portion 301 of the autoclave, and the thickness was 0.4 mm by the HVPE method. All 8 GaN plates of 10 mm in length and 5 mm in width were dissolved. Further, it was confirmed that a hexagonal columnar GaN single crystal grown on the bottom of the inner surface tube 309 and the inner wall surface of the platinum lining of the main body portion 301 of the autoclave was confirmed.

In any of Comparative Examples 12 to 15, a substantially hexagonal columnar GaN single crystal having a length of approximately 3 mm or less which is the same as that shown in the optical micrograph of Fig. 9 was obtained. In any of Comparative Examples 12 to 15, the same X-ray diffraction measurement results as those shown in Fig. 10 were obtained. Therefore, in any of Comparative Examples 12 to 15, it was confirmed that GaN single crystals were obtained in the same manner as in Examples 12 to 27.

The GaN single crystal growth experiment was repeated, and the number of times of repeated crystal growth durability of the shield portion of the autoclave was measured and shown in Table 8. The basis for the number of times of repeated crystal growth and durability is that the number of times of the GaN crystal growth of the autoclave is maintained at a pressure of 120 MPa without replacing the parts of the autoclave.

As is apparent from Table 8, when the shield material in the autoclave of Comparative Examples 12 to 15 was used in a high-temperature and high-pressure ammonia atmosphere, the number of times of repeated crystal growth durability was only one, and it was found that it could not be used repeatedly. In any of Comparative Examples 12 to 15, the abrasion and peeling of the shield portion were observed by the growth of the primary GaN single crystal. The reason for the peeling is considered to be welding. Since the degree of peeling was more intense than Comparative Example 15 and Comparative Example 12, it was found that the higher the use temperature, the greater the degree of peeling. In any of Comparative Examples 12 to 15, the peeling was confirmed in the conical cover shielding portion, and the abrasion was confirmed in the main body shielding portion.

[Industrial availability]

According to the method for producing a nitride single crystal of the present invention and the autoclave, the growth of the nitride single crystal can be achieved at a speed faster than 30 μm/day. Further, the nitride single crystal obtained by the method for producing a nitride single crystal of the present invention and the autoclave may comprise a flat film-like growth layer. Thereby, according to the present invention, a bulk nitride single crystal which can cut a substrate of various orientations can be obtained. Further, according to the present invention, high-quality single crystal grains which can be used as a seed crystal having a size of 1 mm or more which cannot be obtained by the previous ammoniacal method can be produced at an industrially adaptable temperature and pressure. The single crystal system obtained in the present invention can be preferably used for a light-emitting element such as a light-emitting diode or a laser diode.

101, 201. . . pressure gauge

102, 202. . . valve

103, 203. . . Ontology

104, 204. . . catheter

105, 205. . . Raw material container

106, 206. . . raw material

107. . . Seed crystal

108, 208. . . Heater

109, 209. . . Raw material supply site

110, 210. . . Single crystal growth site

111, 211. . . Internal bottom

207. . . board

301. . . Body body

302. . . Body body shielding

303. . . Conical cover

304. . . Conical cover shield

305. . . Outer cover

306. . . Cushion packaging material

307. . . Screw fixing part

308A, 308B. . . Thermocouple

309. . . Inner tube

310. . . catheter

501, 506. . . Three-way connector

502, 504, 505, 507, 509, 511. . . Piping

503. . . Manual valve

508. . . Pressure sensor

510. . . Automatic valve

Fig. 1 is a view showing a state in which a seed crystal is grown in a vertical autoclave to grow a single crystal in the present invention.

Fig. 2 is a view showing a state in which a single crystal is grown by spontaneous nucleation in a vertical autoclave in the present invention.

Figure 3 is a schematic cross-sectional view of the autoclave of the present invention.

Fig. 4 is a schematic cross-sectional view showing a shield portion of the autoclave of the present invention.

Fig. 5 is a schematic view showing an example in which an upper pipe is connected to the autoclave of the present invention.

Fig. 6 is a view showing an optical micrograph of a crystal grain (upper) having a size equal to that of the seed crystal used in the first embodiment and a nitride single crystal (bottom) obtained by growing in the first embodiment.

Fig. 7 is a view showing an X-ray diffraction pattern (XRD pattern) of the GaN single crystal obtained in Example 8.

Fig. 8 is a view showing an optical micrograph of a GaN single crystal obtained in Example 8.

Fig. 9 is a view showing an optical micrograph of a GaN single crystal obtained in Example 13.

Fig. 10 is a view showing an X-ray diffraction pattern (XRD pattern) of the GaN single crystal obtained in Example 13.

1. . . Vertical autoclave

101. . . pressure gauge

102. . . valve

103. . . Ontology

104. . . catheter

105. . . Raw material container

106. . . raw material

107. . . Seed crystal

108. . . Heater

109. . . Raw material supply site

110. . . Single crystal growth site

111. . . Internal bottom

Claims (13)

A method for producing a nitride single crystal, comprising a raw material comprising at least one selected from the group consisting of a polycrystal containing Ga, a nitride containing Ga, and a nitride precursor containing Ga, using ammonia heat The method for producing a nitride crystal containing Ga, comprising the steps of: introducing at least the raw material, one or more acidic mineralizers and ammonia into the autoclave, and satisfying the following conditions (a) to (e), The Ga-containing nitride single crystal is grown: (a) a raw material supply portion where the raw material is disposed, and a single crystal growth portion for growing the Ga-containing nitride single crystal in the autoclave, (b) The single crystal growth portion is a portion where the seed crystal is disposed, (c) the temperature (T1) of the single crystal growth portion is 600 ° C to 850 ° C, and (d) the temperature (T1) of the single crystal growth portion and the raw material supply The relationship between the temperature (T2) of the part (T1-T2) is 1 ° C to 150 ° C, and (e) the pressure in the autoclave is 40 MPa to 250 MPa. A method for producing a nitride single crystal, comprising a raw material comprising at least one selected from the group consisting of a polycrystal containing Ga, a nitride containing Ga, and a nitride precursor containing Ga, using ammonia heat The method for producing a nitride crystal containing Ga, comprising the steps of: introducing at least the raw material, one or more acidic mineralizers and ammonia into the autoclave, and satisfying the following conditions (a) to (e), The Ga-containing nitride single crystal is grown: (a) a raw material supply portion where the raw material is disposed, and a single crystal growth portion for growing the Ga-containing nitride single crystal in the autoclave, (b) the single crystal growth site is a portion where the Ga-containing nitride single crystal is precipitated and grown by spontaneous nucleation, and (c) the temperature (T1) of the single crystal growth portion is 600 ° C to 850 ° C ( d) (T1 - T2) is between 1 ° C and 150 ° C (T) and the pressure in the autoclave is 40MPa~250MPa. The method for producing a nitride single crystal according to claim 1, wherein the seed crystal is a Ga-containing nitride single crystal produced by the method for producing a nitride single crystal according to claim 2. The method for producing a nitride single crystal according to claim 1, wherein the raw material is disposed in a container provided with a plurality of holes or slit-like gaps, and exists between a side of the container and an inner wall of the autoclave A gap of 1 mm or more. The method for producing a nitride single crystal according to any one of claims 1 to 4, wherein the raw material supply portion is present at a position higher than a growth point of the single crystal. The method for producing a nitride single crystal according to any one of claims 1 to 4, wherein the autoclave is a vertical autoclave, and the raw material supply portion is present at a position higher than a growth point of the single crystal. The method for producing a nitride single crystal according to claim 6, wherein the raw material supply portion is present at a height of 10 mm or more from the inner bottom surface of the autoclave, and the single crystal growth portion is present at the raw material supply portion. Between the bottom surface of the autoclave. The method for producing a nitride single crystal according to claim 7, wherein at least one spacer is disposed between the raw material supply portion and the single crystal growth portion. The method for producing a nitride single crystal according to claim 8, wherein the single crystal growth site is a portion where a Ga-containing nitride single crystal is precipitated and grown by spontaneous nucleation, and the single crystal growth portion is disposed at the single crystal growth portion. A plate having corrosion resistance of one or more holes. The method for producing a nitride single crystal according to claim 8, wherein the raw material comprises a Ga-containing nitride polycrystal produced by a vapor phase method. A substrate comprising a nitride single crystal produced by the method for producing a nitride single crystal according to any one of claims 1 to 10. A nitride single crystal produced by the method for producing a nitride single crystal according to any one of claims 1 to 10, and having a maximum size of 1 mm or more. An autoclave for use in a method for producing a nitride single crystal according to any one of claims 1 to 10; maintaining the pressure in the autoclave by closely bonding two or more parts constituting the autoclave The material of the shield portion is an alloy of bismuth and platinum or a bismuth monomer, and the proportion of the constituent elements of the material of the shield portion is 20% by mass to 100% by mass.