JP2013129598A - Method of producing group-iii nitride crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a group-III nitride crystal having a practical size without: complicating processes; using an expensive reaction container; and causing the crystal to be small in size.SOLUTION: A method of producing a group-III nitride crystal from a flux, a nitrogen material, and a melt containing at least a group-III metal, in a reaction container having higher pressure than atmospheric pressure includes: a step of arranging a seed crystal comprising the group-III nitride in the reaction container; a step of supplying the nitrogen material from the outside of the reaction container during crystal growth; and a step of growing the group-III nitride crystal from the center of the seed crystal toward the outside thereof.

Description

  The present invention relates to a method for producing a group III nitride crystal.

  Currently, most of InGaAlN-based (group III nitride) devices used as purple-blue-green light sources are MO-CVD (metal organic chemical vapor deposition) or MBE ( It is fabricated by crystal growth using a molecular beam crystal growth method) or the like. When sapphire or SiC is used as a substrate, crystal defects due to a large difference in thermal expansion coefficient and lattice constant from the group III nitride increase. For this reason, there is a problem that the device characteristics are poor, for example, it is difficult to extend the life of the light emitting device, or the operating power is increased.

  Furthermore, in the case of a sapphire substrate, since it is insulative, it is impossible to take out the electrode from the substrate side as in the conventional light emitting device, and it is necessary to take out the electrode from the nitride semiconductor surface side where the crystal has grown . As a result, there is a problem that the device area is increased, leading to high costs. In addition, a group III nitride semiconductor device fabricated on a sapphire substrate is difficult to separate into chips by cleavage, and it is not easy to obtain a resonator end face required for a laser diode (LD) by cleavage. For this reason, at present, resonator end faces are formed by dry etching, or resonator end faces are formed in a form close to cleavage after polishing the sapphire substrate to a thickness of 100 μm or less. Also in this case, it is impossible to easily separate the resonator end face and the chip as in a conventional LD in a single process, resulting in process complexity and cost.

  In order to solve this problem, it has been proposed to reduce crystal defects by performing selective lateral growth and other devices on a sapphire substrate on a group III nitride semiconductor film.

For example, Non-Patent Document 1 (hereinafter referred to as the first prior art) shows a laser diode (LD) as shown in FIG. In the laser diode of FIG. 9, a GaN low-temperature buffer layer 2 and a GaN layer 3 are sequentially grown on a sapphire substrate 1 by an MO-VPE (metal organic chemical vapor deposition) apparatus, and then a SiO ₂ mask 4 for selective growth is formed. To do. The SiO ₂ mask 4 is formed through a photolithography and etching process after depositing a SiO ₂ film by another CVD (chemical vapor deposition) apparatus. Next, a GaN film 3 ′ having a thickness of 20 μm is grown again on the SiO ₂ mask 4 by the MO-VPE apparatus, so that GaN is selectively grown in the lateral direction and selective lateral growth is not performed. Compared with this, crystal defects are reduced. Further, by introducing a modulation-doped strained superlattice layer (MD-SLS) 5 formed thereon, crystal defects are prevented from extending to the active layer 6. As a result, the device lifetime can be increased as compared to the case where the selective lateral growth and modulation-doped strained superlattice layer is not used.

In the case of this first prior art, it is possible to reduce crystal defects compared to the case where a GaN film is not selectively grown in the lateral direction on the sapphire substrate. The aforementioned problems with cleavage still remain. Furthermore, the crystal growth by the MO-VPE apparatus is required twice with the SiO ₂ mask formation process in between, and a new problem that the process becomes complicated arises.

  As another method, for example, Non-Patent Document 2 (hereinafter referred to as the second prior art) proposes to apply a GaN thick film substrate. In the second prior art, after the selective lateral growth of 20 μm of the first prior art described above, a 200 μm thick GaN thick film is grown by an H-VPE (hydride vapor phase epitaxy) apparatus, and then this thickness is increased. The grown GaN film is polished from the sapphire substrate side to a thickness of 150 μm to produce a GaN substrate. Using the MO-VPE apparatus on this GaN substrate, crystal growth necessary for the LD device is sequentially performed to manufacture the LD device. As a result, in addition to the problem of crystal defects, it is possible to solve the above-described problems related to insulation and cleavage by using a sapphire substrate.

  However, the process of the second conventional technique is more complicated than that of the first conventional technique, which further increases the cost. Further, when a GaN thick film having a thickness of 200 μm is grown by the second prior art method, the stress accompanying the difference in lattice constant and thermal expansion coefficient from sapphire, which is the substrate, is increased, and the substrate is warped or cracked. A new problem arises.

  In order to avoid this problem, Patent Document 1 proposes that the thickness of an original substrate (sapphire and spinel) on which a thick film is grown be 1 mm or more. In this way, by using a substrate having a thickness of 1 mm or more, even when a GaN film having a thickness of 200 μm is grown, the substrate is not warped or cracked. However, such a thick substrate has a high cost of the substrate itself and needs to spend a lot of time for polishing, leading to an increase in the cost of the polishing process. That is, when a thick substrate is used, the cost is higher than when a thin substrate is used. When a thick substrate is used, the substrate is not warped or cracked after the thick GaN film is grown, but stress is relaxed in the polishing process, and warping or cracking occurs during polishing. For this reason, even if a thick substrate is used, a GaN substrate having a high crystal quality cannot be easily produced with a large area.

  On the other hand, Non-Patent Document 3 (hereinafter referred to as “third prior art”) proposes growing a GaN bulk crystal and using it as a homoepitaxial substrate. This technique is a technique for crystal growth of GaN from liquid Ga at a high temperature of 1400 to 1700 ° C. and a nitrogen pressure of several tens of kbar. In this case, a group III nitride semiconductor film necessary for the device can be grown using the bulk-grown GaN substrate. Therefore, a GaN substrate can be provided without complicating the process as in the first and second conventional techniques.

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

As a technique for solving this problem of GaN crystal growth under high temperature and high pressure, Non-Patent Document 4 (hereinafter referred to as “fourth prior art”) proposes a GaN crystal growth method using Na as a flux. ing. In this method, sodium azide (NaN ₃ ) as a flux and metal Ga are used as raw materials, and sealed in a stainless steel reaction vessel (inner dimensions; inner diameter = 7.5 mm, length = 100 mm) in a nitrogen atmosphere, By holding the reaction vessel at a temperature of 600 to 800 ° C. for 24 to 100 hours, a GaN crystal is grown. In the case of the fourth prior art, crystal growth at a relatively low temperature of about 600 to 800 ° C. is possible, and the pressure in the container is at most about 100 kg / cm ^2, which is higher than that of the third prior art. It is a feature that can be lowered. However, the problem with this method is that the crystal size obtained is small enough to be less than 1 mm. This size is too small for practical use of the device, as in the case of the third prior art.

  The present invention does not complicate the process that is the problem of the first and second prior arts, without using the expensive reaction vessel that is the problem of the third prior art, and the third and fourth. The present invention provides a method for producing a group III nitride crystal having a practical size for manufacturing a device such as a high-performance light-emitting diode or LD without reducing the size of the crystal, which is a problem of the prior art. The purpose is that.

  In order to solve the above-described problems and achieve the object, a method for producing a group III nitride crystal according to the present invention includes a melt containing at least a group III metal in a reaction vessel having a pressure higher than atmospheric pressure. In the production method for producing a group III nitride crystal from a flux and a nitrogen raw material, a step of disposing the group III nitride seed crystal in the reaction vessel; and during the crystal growth, the nitrogen raw material is supplied from the outside of the reaction vessel. And a step of growing a group III nitride crystal outward from the center of the seed crystal.

  According to the present invention, it is possible to produce a group III nitride crystal having a higher quality and a larger size than the prior art.

It is sectional drawing which shows the crystal growth apparatus used for one Example of this invention. It is sectional drawing of the crystal growth apparatus used for the other Example of this invention. It is sectional drawing of the GaN crystal growth apparatus used for the further another Example of this invention. It is sectional drawing of the GaN crystal growth apparatus used for the further another Example of this invention. It is sectional drawing of the GaN crystal growth apparatus used for the further another Example of this invention. It is sectional drawing of the GaN crystal growth apparatus used for the further another Example of this invention. It is sectional drawing of the GaN crystal growth apparatus used for the further another Example of this invention. It is a figure which shows an example of the seed crystal and seed crystal holder which are used for the crystal growth apparatus of FIG.1, FIG.2, FIG.4, FIG.5, FIG.6 and FIG. It is sectional drawing which shows the conventional laser diode.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  In the present invention, in a reaction vessel, a melt containing at least a group III metal (for example, Ga (gallium)), a flux (for example, metal Na or a compound containing Na (such as sodium azide)), and a nitrogen source are in contact with each other. From the region, a group III nitride crystal (for example, GaN crystal) is grown using a seed crystal (for example, GaN crystal).

  Here, the flux may be previously dissolved in a melt containing a group III metal, or may be supplied to the crystal growth region in a gaseous state. Moreover, in this invention, a nitrogen raw material is a nitrogen molecule | numerator produced | generated from the nitrogen molecule, atomic nitrogen, or the compound containing nitrogen, or atomic nitrogen.

  A device using a group III nitride crystal can be applied to a blue light source for optical disks, a blue light emitting diode, a high-frequency electronic device operating at high temperature, and the like.

  FIG. 1 is a diagram showing a configuration example of a crystal growth apparatus according to the present invention. Referring to FIG. 1, a reaction vessel 101 contains a melt containing at least a group III metal (eg, Ga), more specifically, for example, a group III metal (eg, Ga (gallium)) and a flux (eg, A mixed melt 102 with metal Na or a compound containing Na (such as sodium azide) is contained. The reaction vessel 101 is provided with a heating device 105 that can be controlled to a temperature at which crystals can be grown.

  Further, a seed crystal (for example, GaN crystal) 103 is held by a seed crystal holder 104 as a seed crystal holding means so as to come into contact with a gas-liquid interface 113 which is a boundary region between the gas in the reaction vessel 101 and the melt 102. ing. The seed crystal holder 104 is connected to the outside of the reaction vessel 101 so that the position can be changed from the outside. That is, the seed crystal holder 104 is configured to be able to change its position from the outside so that the seed crystal 103 and the grown group III nitride crystal can be pulled up.

  In FIG. 1, a flux container 106 and a heating device 108 are provided outside the reaction container 101 in order to control the vapor pressure of the flux. A flux (for example, Na) 107 is accommodated inside the flux container 106, and the flux container 106 and the reaction container 101 are connected by a connecting pipe 110. The flux 107 in the flux container 106 can be controlled to a desired flux vapor pressure (Na pressure) by the heating device 108. In other words, when Na is used as the flux, the vapor pressure of Na can be controlled.

  That is, the crystal growth apparatus of FIG. 1 is configured such that the vapor pressure can be controlled by Na present in the reaction vessel 101 and Na supplied from the flux vessel 106. In order to improve controllability of nucleation, the case where the Na vapor pressure from the flux container 106 becomes dominant is also within the scope of application of the present invention.

  On the other hand, a nitrogen raw material (for example, nitrogen (N)) can be supplied into the reaction vessel 101 from the outside of the reaction vessel 101 through the nitrogen supply pipe 111. At this time, a pressure adjusting mechanism 112 is provided to adjust the nitrogen pressure in the reaction vessel 101. The pressure adjustment mechanism 112 includes, for example, a pressure sensor and a pressure adjustment valve.

  That is, the crystal growth apparatus in FIG. 1 basically grows a group III nitride crystal from a melt 102 containing at least a group III metal, a flux, and a nitrogen source in a reaction vessel 101. A seed crystal holding means 104 for holding the group III nitride seed crystal 103, a flux supply means (106, 108, 110) for supplying flux with controllable flux vapor pressure, and nitrogen with controllable nitrogen pressure. Nitrogen supply means (111, 112) for supplying the raw material are provided, and by moving the seed crystal holding means 104, the region where the seed crystal 103, the melt 102, and the nitrogen raw material can contact can be moved. It has become.

  In the crystal growth apparatus having such a configuration, a group III nitride crystal (for example, a GaN crystal) grows using the seed crystal 103 as a nucleus under conditions of a growth temperature at which crystal growth is possible, nitrogen pressure, and Na pressure. That is, in the reaction vessel 101, the seed crystal 103 is in contact with the melt 102 containing at least a group III metal and the flux, and the melt 102 and the nitrogen raw material react to form a group III nitride using the seed crystal 103 as a nucleus. Crystal grows. Here, by moving the seed crystal holder 104, the seed crystal 103 and the group III nitride crystal grown around the seed crystal 103 move, and a larger group III nitride crystal can be grown. That is, when the region where the seed crystal 103, the melt 102, and the nitrogen material are in contact with each other moves, the crystal growth region moves, and the group III nitride crystal grows and increases in size. At this time, the growth of the group III nitride crystal mainly occurs at the gas-liquid interface 113.

  That is, in a state where there is sufficient Group III metal Ga, the vapor pressure of Na, which is a flux, and the vapor pressure of nitrogen (N), which is a nitrogen raw material, can be controlled, thereby allowing continuous Group III nitride crystals (GaN crystals). Thus, a group III nitride crystal (GaN crystal) can be grown to a desired size.

  FIG. 2 is a diagram showing a modification of the crystal growth apparatus of FIG. In FIG. 2, the same parts as those in FIG. In the crystal growth apparatus of FIG. 2, the limiting means (for example, cover) 114 which limits the area | region where the seed crystal 103, the melt 102, the flux, and the nitrogen raw material contact is provided in the crystal growth apparatus of FIG. That is, in the example of FIG. 2, the gas-liquid interface 113, which is a boundary region between the gas in the reaction vessel 101 and the melt 102, is limited to a region where the seed crystal 103 is present, and other regions are limited means. As a result, the melt 102 and the gas are spatially separated so as not to contact each other. In other words, the cover 114 is provided with an opening 115 that can be controlled to a predetermined size, and the melt 102 can be brought into contact with the seed crystal 103 only through the opening 115. .

  That is, the limiting means (cover) 114 has an opening 115 that can be controlled to a predetermined size, and the opening 115 of the limiting means 114 is in contact with the seed crystal 103 or a crystal grown from the seed crystal. The other region covers the melt 102. The size of the opening 115 of the limiting means 114 can be changed to an arbitrary shape so that the crystal can pass through the contact of the group III nitride crystal.

  FIGS. 3A and 3B are diagrams (top views) showing an example of the limiting means (cover) 114 in the crystal growth apparatus of FIG. FIG. 3A is a diagram showing a state in which the opening 115 of the limiting unit 114 is closed. The limiting means 114 is formed of, for example, a small fan-shaped cell so that the opening 115 of the limiting means 114 can be opened to an appropriate size outward (in the direction of the arrow Q) as crystal growth proceeds. In addition, the cell moves outward. FIG. 3B is a view showing a state where a group III nitride crystal (GaN crystal) 150 having a certain size is obtained. As described above, the size of the crystal 150 increases with the passage of time, and accordingly, the cell of the limiting unit 114 moves, and the opening 115 of the limiting unit 114 has a shape matching the size of the group III nitride (GaN) crystal 150. Opens. As a result, the region where the group III nitride crystal (GaN crystal), the melt 102, and the nitrogen that is the group III material are in contact with each other is limited to the vicinity of the group III nitride crystal (GaN crystal). It is possible to efficiently grow a desired group III nitride crystal (GaN crystal) without causing nucleation and crystal growth.

  As described above, in the configuration of FIG. 2, a region where the melt (for example, a mixed melt of group III metal and flux) 102 and the nitrogen raw material (nitrogen) is in contact with the cover 114 is the gas-liquid interface of the opening 115. It is limited to 113. At this time, the opening 115 of the cover 114 is made of an appropriate size and material, so that the melt 102 can be lifted up to the height of the seed crystal 103 as shown in FIG. As a result, the gas-liquid interface 113 can be limited to the vicinity of the seed crystal 103, and the margin of crystal growth conditions for growing only in the vicinity of the seed crystal 103 region can be increased. That is, it becomes easy to suppress nucleation and crystal growth outside the limited region.

  That is, in the crystal growth apparatus of FIG. 2, the limiting means (cover) 114 limits the region where the seed crystal 103, the melt 102, the flux, and the nitrogen source are in contact with each other. The flux and the nitrogen material cannot be in contact with each other. In other words, a region where all of the seed crystal 103, the melt 102, the flux, and the nitrogen raw material are in contact with each other is limited to the opening 115 of the limiting means 114, and the group III nitride crystal growth only in the vicinity of this region. Advances. In other regions, the melt 102 containing at least a group III metal is not in contact with the flux and the nitrogen material, and crystal growth hardly occurs.

  FIG. 4 is a diagram showing another modification of the crystal growth apparatus of FIG. In FIG. 4, the same parts as those in FIG. In the crystal growth apparatus of FIG. 4, the connecting tube 110 connecting the flux vessel 106 and the reaction vessel 101 is introduced into the reaction vessel 101 so as to cover the outside of the seed crystal holder 104. The shape is such that the flux can be supplied from the tip portion 117 of 110. That is, the crystal growth apparatus of FIG. 4 has a function of supplying a flux from the periphery holding the group crystal nitride seed crystal 103.

  In the crystal growth apparatus having such a configuration, the group III nitride crystal can be preferentially grown in this region with the seed crystal 103 as a nucleus by supplying the flux only from the tip portion 117 of the connecting tube 110. Become. That is, since the flux is supplied from the periphery holding the seed crystal 103, the region where the seed crystal 103 is in contact with the flux, the melt 102, and the nitrogen material is limited to this. Under this environment, by moving the seed crystal holder 104 upward (by pulling up the seed crystal holder 104), the seed crystal 103 is pulled up, and the group III nitride crystal grown on the seed crystal 103 and its periphery is formed. It is possible to move upward and grow a larger group III nitride crystal (GaN crystal). At this time, the growth of the group III nitride crystal mainly occurs at the gas-liquid interface 113.

  In this way, when the flux is supplied only from the tip portion 117 of the connecting pipe 110, the group III nitride crystal grows preferentially in this region with the seed crystal 103 as a nucleus, and nuclei are generated in other regions. In addition, crystal growth can be suppressed, and the margin of crystal growth conditions can be increased to increase the size of the group III nitride crystal (GaN crystal substrate).

  FIG. 5 is a diagram showing another modification of the crystal growth apparatus of FIG. In FIG. 5, the same parts as those in FIG. In the crystal growth apparatus of FIG. 5, a region of the inner wall of the reaction vessel 101 where a melt 102 containing at least a group III metal (for example, a mixed melt containing a group III metal and a flux) 102 is formed of nitride. Yes.

  That is, in the crystal growth apparatus of FIG. 5, a second reaction vessel 120 is provided inside the reaction vessel 101, and this second reaction vessel 120 is formed of nitride, for example, BN (boron nitride). Yes. In the second reaction vessel 120, a melt containing at least a group III metal (for example, a mixed melt containing a group III metal and a flux) 102 is accommodated, and a region in contact with the melt 102 is as follows. All are only the second reaction vessel 120. Since the material of the second reaction vessel 120 is a nitride such as BN, impurities other than nitrogen are not mixed into the melt 102, and a high-purity group III nitride crystal (GaN crystal) can be grown. It becomes. At this time, the growth of the group III nitride crystal (GaN crystal) mainly occurs at the gas-liquid interface 113.

  In the above example, the material of the second reaction vessel 120 is BN, but other than this, nitrides such as SiN and TiN which are difficult to decompose can be used. The example of FIG. 5 is applied to the crystal growth apparatus of FIG. 1, but also in the crystal growth apparatus of FIG. 2 or FIG. The second reaction vessel 120 formed of boron) can be provided, and the entire region in contact with the melt 102 can be the second reaction vessel 120 alone.

  FIG. 6 is a view showing another modification of the crystal growth apparatus of FIG. In FIG. 6, the same parts as those in FIG.

  In the crystal growth apparatus of FIG. 6 as well, the seed crystal 103 is held by the seed crystal holder 104 so as to be in contact with the gas-liquid interface 113 which is the boundary region between the gas in the reaction vessel 101 and the melt 102 as in FIG. Here, the seed crystal holder 104 is connected to a seed crystal pulling machine 130 located outside the reaction vessel 101, and the position can be changed from the outside by the seed crystal pulling machine 130.

  In the crystal growth apparatus having such a configuration, a group III nitride crystal (GaN crystal) grows using the seed crystal 103 as a nucleus under conditions of a growth temperature at which crystal growth is possible, nitrogen pressure, and Na pressure. Here, the seed crystal holder 104 is moved upward (in the direction of arrow R) by the seed crystal pulling machine 130 (the seed crystal 103 is moved upward, which is the side opposite to the side where the melt 102 is present). Therefore, it becomes possible to grow a group III nitride crystal (GaN crystal) 140 in the downward direction of the seed crystal 103 (a group III nitride 140 can be grown in a region where the melt and the nitrogen source are in contact with each other). Thus, it becomes possible to grow a large group III nitride crystal substrate (GaN substrate) with controlled crystal orientation.

  FIG. 7 is a view showing another modification of the crystal growth apparatus of FIG. In FIG. 7, the same parts as those in FIG.

  In the crystal growth apparatus of FIG. 7 as well, the seed crystal 103 is held by the seed crystal holder 104 so as to be in contact with the gas-liquid interface 113 which is the boundary region between the gas in the reaction vessel 101 and the melt 102. The seed crystal holder 104 is connected to a seed crystal puller 131 located outside the reaction vessel 101 so that the position can be changed from the outside.

  In the crystal growth apparatus having such a configuration, a group III nitride crystal (GaN crystal) grows using the seed crystal 103 as a nucleus under conditions of a growth temperature at which crystal growth is possible, nitrogen pressure, and Na pressure. Here, the seed crystal holder 104 is moved downward (in the direction of the arrow P) by the seed crystal puller 131 (by moving the seed crystal 103 in the direction in which the seed crystal 103 sinks in the melt 102). The group III nitride crystal (GaN crystal) 141 can be grown upward, and a large group III nitride crystal substrate (GaN substrate) with a controlled crystal orientation can be grown. At this time, there is no seed crystal 103 or a group III nitride crystal derived therefrom or a seed crystal holder 104 or the like above the gas-liquid interface 113 where crystal growth occurs. Accordingly, since there is nothing that prevents gas such as nitrogen or flux vapor from coming into contact with the gas-liquid interface 113, the crystal growth at the gas-liquid interface 113 proceeds smoothly, and the crystal High quality, large crystals can be grown.

  In the above example, the seed crystal puller 131 is used to lower the seed crystal 103 and the seed crystal holder 104 downward. Instead, the seed crystal 113 is raised by raising the gas-liquid interface 113. May be moved relatively downward.

  FIG. 8 is a view showing an example of the seed crystal 103 and the seed crystal holder 104 used in the crystal growth apparatus shown in FIGS. 1, 2, 4, 5, 6, and 7. In the example of FIG. 8, the seed crystal 103 has a plate shape and is held by the seed crystal holder 104. More specifically, in the example of FIG. 8, the length l and the width w of the seed crystal 103 are larger than the thickness d. After immersing the seed crystal 103 having such a shape in the melt 102, the seed crystal 103 is moved under conditions that allow crystal growth, so that a group III nitride crystal having a width w of at least the seed crystal 103 is obtained. It becomes possible to grow.

  That is, the group III nitride crystal grown using the seed crystal 103 having such a shape has many regions having a wide width w, and by cutting it into an appropriate size, it can be easily used as a substrate for crystal growth. Application becomes possible. In the example of FIG. 8, a plate-like crystal is used as a seed crystal. However, other than that, it is long in the width direction, such as a rod-like one having a rectangular cross section, and is in contact with the gas-liquid interface 113 during crystal growth. Anything that is possible.

  In other words, the shape of the seed crystal 103 is such that one side of the surface substantially parallel to the gas-liquid interface 113 is long and whether the surface substantially parallel to the gas-liquid interface 113 is in contact with the gas-liquid interface 113 in the initial stage of crystal growth. Alternatively, any shape in which the seed crystal 103 is immersed in the melt 102 may be used.

Group III nitride crystals can be grown by the crystal growth apparatus as described above. As a specific example of the crystal growth method, Ga is used as a Group III metal, Nitrogen gas is used as a nitrogen raw material, Na is used as a flux, the temperature of the reaction vessel 101 and the flux vessel 106 is 750 ° C., and the nitrogen pressure is constant at 100 kg / cm ² G. To. Under such conditions, GaN crystals can be grown.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention does not complicate the process that is the problem of the first and second prior arts, without using the expensive reaction vessel that is the problem of the third prior art, and the third and fourth. However, the size of the crystal, which is a problem of the prior art, can be reduced to a practical size for fabricating devices such as optical disk light sources, high-performance light-emitting diodes, and high-frequency high-frequency electronic devices. It is applied to a group III nitride crystal or a group III nitride crystal substrate.

  101 reaction vessel, 102 melt, 103 seed crystal, 104 seed crystal holder, 105 heating device, 106 flux container, 107 flux, 108 heating device, 110 connecting tube, 111 nitrogen supply tube, 112 pressure adjusting mechanism, 113 gas-liquid interface , 114 limiting means (cover), 115 opening, 117 tip of connecting pipe, 120 second reaction vessel, 130 seed crystal pulling machine, 140 III nitride crystal, 131 seed crystal pulling machine, 141 III nitride Crystal, Group III III nitride crystal

Japanese Patent Laid-Open No. 10-256661

Japanese Journal of Applied Physics Vol.36 (1997) Part 2, No.12A, L1568-1571. Applied Physics Letters, Vol. 73, No. 6, P832-834 (1998). Journal of Crystal Growth, Vol.189 / 190, p.153-158 (1998). Chemistry of Materials Vol.9 (1997) p.413-416.

Claims (3)

In a Group III nitride crystal production method for producing a Group III nitride crystal from a melt containing at least a Group III metal, a flux, and a nitrogen raw material in a reaction vessel having a pressure higher than atmospheric pressure,
Placing the group III nitride seed crystal in the reaction vessel;
Supplying the nitrogen raw material from the outside of the reaction vessel during crystal growth;
Growing a group III nitride crystal outward from the center of the seed crystal;
A method for producing a group III nitride crystal containing In the step of growing the group III nitride crystal outward from the center of the seed crystal, the group III nitride crystal grows in a direction substantially parallel to at least the gas-liquid interface.
The method for producing a group III nitride crystal according to claim 1. The seed crystal has a rod shape,
A method for producing a group III nitride crystal according to claim 1 or 2.

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