Liquid phase growth and doping method of large-size nitride crystal

Abstract

The invention discloses a liquid phase growth and doping method of large-size nitride crystals, which comprises the following steps: placing a nitride polycrystalline raw material containing doping elements and a mineralizing agent into a raw material area in a reactor, placing nitride seed crystals into a growth area in the reactor, and separating the raw material area from the growth area by a baffle plate, the baffle is provided with a through hole capable of communicating the raw material area with the growth area, and the reactor is filled with a liquid-phase reaction medium; the temperatures of the raw material area and the growth area are set to be a first temperature and a second temperature respectively, and the first temperature is higher than the second temperature, so that the nitride single crystal is obtained through growth. According to the method, uniform doping and large-size growth of the nitride single crystal can be achieved through a liquid phase method, then the large-size nitride single crystal which is high in crystal quality, smooth in surface and uniform in doping is prepared, the process scale is easy to amplify, and good industrialization prospects are achieved.

Description

Technical Field

[0001] The present application relates to a method for preparing a nitride single crystal, and in particular to a method for liquid phase growth and doping of a large-sized nitride crystal. Background Art

[0002] In recent years, GaN devices have shown great application prospects in full-color display, semiconductor lighting and power electronics, microwave power and high-energy detection. High electron mobility transistors based on the two-dimensional electron gas structure of the GaN material system are core components in future phased array radars, 5G mobile communications, smart grids, etc., and play an indispensable and important role in many fields due to their advantages such as high electron mobility, high power density, high efficiency and high breakdown electric field.

[0003] The bottleneck factor for further improving the performance of GaN-based devices is that it is difficult to obtain high-quality GaN single crystal substrate materials. Electrical performance is a key parameter for the development of GaN single crystal substrates as semiconductor materials, and the electrical performance of GaN single crystal substrates depends on the doping quality.

[0004] Some researchers have proposed a method for preparing a gallium nitride single crystal substrate containing doping elements by using GaN source materials, dopant sources and mineralizers, and based on liquid phase growth. Other researchers have proposed a method for preparing gallium nitride single crystals containing doping elements by doping Zn elements using the ammonothermal method. Although these methods can achieve the doping of GaN single crystals, they will lead to a decrease in crystal quality, deterioration of surface morphology, and uneven doping. Summary of the invention

[0005] The main purpose of the present application is to provide a liquid phase growth and doping method for large-sized nitride crystals to overcome the deficiencies in the prior art.

[0006] In order to achieve the aforementioned invention objectives, the technical solutions adopted in this application include: One aspect of the present application provides a liquid phase growth and doping method for a large-sized nitride crystal, comprising: Placing a nitride polycrystalline raw material containing doping elements and a mineralizer into a raw material area in a reactor, and placing a nitride seed crystal into a growth area in the reactor, and separating the raw material area from the growth area with a baffle, wherein the baffle has a through hole and / or a gap is left between the edge of the baffle and the inner wall of the reactor, and the through hole and / or the gap are used to connect the raw material area with the growth area; Then, the reactor is filled with a liquid reaction medium and the reactor is sealed; Then, the temperatures of the raw material zone and the growth zone are set to a first temperature and a second temperature respectively, wherein the first temperature is higher than the second temperature, so as to grow and obtain a nitride single crystal.

[0007] In the present application, the nitride is mainly a Group III metal nitride, such as GaN, InN, AlN, AlGaN, AlInGaN, etc., preferably GaN.

[0008] In the present application, the nitride polycrystalline raw material containing doping elements can be synthesized using chemical methods, such as gas phase methods such as HVPE and liquid phase methods such as ammonothermal method. It can be used to prepare nitride single crystals by liquid phase methods such as ammonothermal method, flux method, high pressure solution method, etc., so that the doping elements and raw materials can be dissolved, transferred and crystallized synchronously during the ammonothermal growth process, and then evenly incorporated into the nitride single crystal, thereby improving the doping uniformity of the nitride single crystal and avoiding the problem of uneven doping in the existing nitride crystal doping method due to the large difference between the solubility of the doping elements in the liquid phase solvent and the solubility of the nitride. In particular, the use of the nitride polycrystalline raw material can achieve multi-element co-doping and ensure uniform doping of each element.

[0009] The "large-sized nitride crystal" mentioned in this application refers to a nitride crystal having a diameter of more than 2 inches.

[0010] In one embodiment, the doping element includes one or more combinations of Si, Ge, Mg, Zn, Fe, and rare earth elements, but is not limited thereto.

[0011] For example, a nitride crystal with high conductivity can be realized by doping Si or Ge. A semi-insulating nitride crystal can be realized by doping Fe, a p-type nitride crystal can be realized by doping Mg, and a nitride crystal with set optical properties can be realized by doping rare earth elements. For example, the rare earth element can be lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium or yttrium, etc.

[0012] Furthermore, the electrical properties of nitride crystals can be significantly improved by co-doping with multiple elements. For example, when preparing GaN single crystals for GaN photoconductive switches, the withstand voltage performance of GaN photoconductive switches can be improved by co-doping with Fe-Si, where the Fe element in GaN mainly acts as a deep level defect impurity to compensate for the carrier concentration, thereby achieving a semi-insulating state, and the Si element acts as a donor impurity to increase the carrier concentration, so that a large number of photogenerated carriers are instantly generated under light excitation, thereby increasing the output current and reducing the on-resistance. This performance is mainly manifested in the on state of the photoconductive switch.

[0013] In one embodiment, the doping concentration of the doping element in the gallium nitride polycrystalline raw material is 10 17 -10 21 / cm 3 If the doping concentration is too high or too low, the electrical properties of the resulting nitride crystal will be reduced.

[0014] In one embodiment, the gallium nitride polycrystalline raw material is powder, and the particle size is 1-10 mm.

[0015] In the present application, by forming a temperature difference between the raw material zone and the growth zone, convection can be formed in the liquid phase reaction system between the raw material zone and the growth zone, thereby promoting the continuous growth of nitride crystals. At the same time, by setting a baffle between the raw material zone and the growth zone, the flow field and temperature field in the growth zone can be made more uniform, thereby ensuring the uniform growth and doping of nitride single crystals and improving the crystal quality and its surface morphology.

[0016] In one embodiment, the through hole is opened at the center of the baffle, and the ratio of the radial area of ​​the through hole to the radial area of ​​the baffle is less than 1%, so that a temperature difference is generated between the raw material zone and the growth zone, thereby forming convection.

[0017] In one embodiment, the baffle is provided with a plurality of through holes, one of which is arranged at the center of the baffle, and the remaining through holes are symmetrically arranged on the baffle, and the apertures of the plurality of through holes decrease successively from the center to the edge of the baffle, and the ratio of the radial area of ​​the through hole located at the center of the baffle to the radial area of ​​the baffle is less than 1%, and the ratio of the sum of the radial areas of the remaining through holes to the radial area of ​​the baffle is 3%-20%, so as to better promote convection of the reaction system between the raw material zone and the growth zone, and ensure the uniformity of the flow field in the growth zone.

[0018] In one embodiment, the baffle is made of an inert material. The inert material can be selected from metal or non-metal materials that are resistant to high temperatures and will not react with any substance in the liquid phase growth system of the nitride single crystal under high temperature conditions, for example, it can be preferably selected from gold, silver, tungsten, molybdenum, etc.

[0019] In one embodiment, there are multiple growth zones and multiple baffles, and the multiple growth zones and the raw material zones are distributed in sequence along a set direction, wherein the baffles are also arranged between adjacent growth zones.

[0020] The setting direction is preferably a vertical direction. Further, the plurality of growth areas and the raw material areas can be arranged in sequence from top to bottom.

[0021] Among them, by arranging baffles between the growth zones, the uniformity of the flow field and the temperature field in each reaction zone can be further guaranteed.

[0022] In one embodiment, the filling degree of the liquid phase reaction medium in the reactor is 60%-70%. The filling degree refers to the ratio of the volume of the liquid phase reaction medium in the reactor to the volume of the reactor cavity.

[0023] In one embodiment, the liquid reaction medium comprises liquid ammonia.

[0024] In the present application, the reactor may be a high-pressure reactor.

[0025] In the present application, the reactor can be placed in a heating device with multiple temperature zones, and each growth zone and raw material zone in the reactor can be located in a different temperature zone, so as to achieve temperature control in each growth zone and raw material zone. Exemplarily, the heating device can be a vertical tube furnace with more than two temperature zones.

[0026] Furthermore, the temperature of each growth zone and raw material zone can be set according to the type of mineralizer. For example, if an acidic mineralizer (such as ammonium halides such as NH4F, NH4Cl, NH4Br or mixtures thereof in different proportions) is used, the temperature of the growth zone can be set to 400-550°C; if an alkaline mineralizer (such as alkali metal amide compounds such as NaNH2, KNH2, LiNH2 or mixtures thereof in different proportions, or alkali metals such as Li, Na, K, Cs or mixtures thereof in different proportions) is used, the temperature of the growth zone can be set to 500-650°C; if a neutral mineralizer is used, the temperature of the growth zone can be set to 400-600°C.

[0027] See also Figure 1 In the present application, by using a nitride polycrystalline raw material containing one or more doping elements (i.e., a single element doping raw material or a multi-element doping raw material), and selecting a long strip nitride crystal of a suitable size as a seed crystal, and by adjusting the type and ratio of the mineralizer, etc., the III-group nitride can be preferentially grown along the specified crystal plane direction to form a crystal ingot, thereby realizing the diameter expansion growth of the crystal; by cutting the crystal ingot, a long strip nitride crystal with an enlarged size can be obtained, and the long strip nitride crystal with an enlarged size can be further used as a seed crystal to iterate the above growth process again, thereby realizing a large size and high quality (low dislocation density less than 5×10 -3 cm -2 ) Preparation of nitride single crystals.

[0028] Exemplarily, the method may include: S1. Selecting a first elongated GaN wafer as the gallium nitride seed crystal to grow a first gallium nitride single crystal.

[0029] S2, cutting the first gallium nitride single crystal to obtain a second long-strip GaN wafer, wherein the second GaN wafer is larger than the first GaN wafer in overall size. The direction of cutting the first gallium nitride single crystal is preferably perpendicular to the a direction of the crystal.

[0030] S3. Using the second GaN wafer as the gallium nitride seed crystal to grow a second gallium nitride single crystal, wherein the overall size of the second gallium nitride single crystal is greater than that of the first gallium nitride single crystal.

[0031] Repeat the operations of S1 to S3 one or more times until a gallium nitride single crystal having a predetermined size is obtained.

[0032] Exemplarily, the nitride seed crystal is a c-plane elongated seed crystal.

[0033] Exemplarily, during the process of growing a gallium nitride single crystal, GaN preferentially grows along the a-direction of the crystal.

[0034] In a more specific implementation case, a c-plane elongated GaN seed crystal is used, and by adjusting process parameters such as the concentration of the mineralizer and the temperature, it is preferentially grown along the a-direction. By utilizing the low dislocation density of GaN lateral growth, the dislocation density of the growing GaN single crystal can be reduced by two orders of magnitude, and diameter expansion growth can be achieved.

[0035] In one embodiment, the method specifically includes: setting the temperature of the raw material zone and the growth zone to 500-650°C and 400-650°C respectively, and setting the growth pressure to 200MPa-300MPa, and the growth time to 14-100 days, so as to grow and form the nitride single crystal. Preferably, the temperature of the growth zone can be set to 550-650°C, and the temperature of the growth zone can be set to 450-550°C.

[0036] In the present application, the nitride seed crystal can be fixed in the growth region by silver wire suspension or the like.

[0037] Another aspect of the present invention provides a nitride single crystal having the advantages of high crystal quality, good surface morphology, uniform doping, large size, etc., which is prepared by the liquid phase growth and doping method of the large-size nitride crystal.

[0038] Furthermore, the dislocation density of the nitride single crystal is less than 5×10 -3 cm -2 .

[0039] Preferably, the nitride single crystal is a gallium nitride single crystal.

[0040] Compared with the prior art, the method of the present invention can achieve uniform doping and large-size growth of nitride single crystals through a liquid phase method, thereby obtaining large-size nitride single crystals with high crystal quality, smooth surface, and uniform doping. The process scale is easy to expand and has good industrial prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The exemplary embodiments of the present application are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, and are not intended to exhaust all feasible methods of the present application, nor to limit the scope of protection of the present application.

[0042] Figure 1 It is a process flow diagram of a liquid phase growth and doping method of a large-size gallium nitride crystal in one embodiment of the present application; Figure 2 It is a schematic diagram of growing a large-sized GaN single crystal by an ammonothermal method in Example 1 of the present application; Figure 3 It is a schematic diagram of a method of growing a GaN single crystal by expanding the diameter of a c-plane long strip seed crystal in Example 1 of the present application. DETAILED DESCRIPTION

[0043] The technical solution of the present application will be explained in more detail below in conjunction with several embodiments, but these specific descriptions are only used to teach those skilled in the art how to implement the present invention, rather than to exhaustively enumerate all feasible methods of the present invention, nor to limit the scope of the present invention.

[0044] Example 1 See also Figure 1-Figure 2 A method for growing a large-size GaN single crystal by an ammonothermal method comprises the following steps: (1) A high-pressure reactor 1 is selected as a reactor, and in an inert atmosphere glove box, a polycrystalline raw material 3 containing doping elements and a mineralizer 4 are filled into a raw material area 11 in the reactor 1, wherein the polycrystalline raw material 3 containing doping elements is a powder, the average particle size of the powder particles is about 1.5 mm, and the powder is doped with a concentration of about 2.2×10 19 / cm 3 The Fe element and concentration are about 3.5×10 20 / cm 3Si element, and ammonium chloride is selected as the mineralizer 4. Also, a c-plane long strip GaN seed crystal 6 with a size of about 50mm×10mm×0.3mm is suspended in the growth zone 12 in the reactor 1 by a silver wire. The growth zone 12 is located above the raw material zone 11, and the raw material zone 11 and the growth zone 12 are separated by a tungsten baffle 2 with a through hole. The baffle 2 is provided with a plurality of through holes penetrating the baffle in the thickness direction, one of which is arranged at the center of the baffle, and the other through holes are symmetrically arranged on the baffle, and the apertures of the plurality of through holes decrease in sequence from the center to the edge of the baffle, and the ratio of the radial area of ​​the through hole located at the center of the baffle to the radial area of ​​the baffle is about 0.8%, and the ratio of the sum of the radial areas of the other through holes to the radial area of ​​the baffle is about 12%, and these through holes can all be circular through holes. Then, liquid ammonia 5 is injected into the reactor 1, and the filling degree is about 65%, and the reactor 1 is sealed. Figure 2 Here m, a, and c are different crystal plane directions of the seed crystal.

[0045] (2) The reactor loaded with the polycrystalline raw material 3, the mineralizer 4 and the liquid ammonia 5 is placed in a vertical tube furnace with two temperature zones for heating, and the temperature of the temperature zone corresponding to the raw material zone 11 is set to about 600°C, and the temperature of the temperature zone corresponding to the growth zone 12 is set to about 500°C. The growth pressure is controlled to be about 250 MPa, and the growth time is about 20 days to obtain a GaN single crystal with a diameter of about 2.1 inches and a defect density of about 2.1×10 4 / cm 2 The surface is smooth and flat, and the doping concentrations of Fe and Si are about 3.1×10 18 / cm 3 , about 2.2×10 19 / cm 3 , and Fe and Si elements are evenly distributed in the GaN single crystal.

[0046] Comparative Example 1 The method for growing large-sized GaN single crystals by an ammonothermal method provided in this comparative example is basically the same as that in Example 1, except that: in step (1) of this comparative example, a mixture of ferric chloride, silicon iodide and GaN polycrystalline raw material is used to replace the polycrystalline raw material 3 containing doping elements, and the molar amount of the doping element and GaN in the mixture is equal to the molar amount of the doping element and GaN in the polycrystalline raw material 3.

[0047] The size of the GaN single crystal finally obtained in this comparative example is about 2.0 inches, and the defect density is about 6.5×10 7 / cm 2 There are many tiny cracks on the surface, and the doping concentrations of Fe and Si are about 3.6×10 17 / cm 3 , about 2.4×1019 / cm 3 , the Si element is evenly distributed in the GaN single crystal, while the Fe element is unevenly distributed in the GaN single crystal.

[0048] Comparative Example 2 The method for growing large-size GaN single crystals by using the ammonothermal method provided in this comparative example is basically the same as that in Example 1, except that the ratio of the radial area of ​​the through hole located at the center of the baffle to the radial area of ​​the baffle is about 1.2%.

[0049] The size of the GaN single crystal finally obtained in this comparative example is about 1.5 inches, and the defect density is about 4×10 8 / cm 2 There are many tiny pits and cracks randomly distributed on the surface, and the doping concentrations of Fe and Si are about 2.7×10 18 / cm 3 , about 1.9×10 19 / cm 3 , Fe and Si elements are unevenly distributed in GaN single crystals.

[0050] Comparative Example 3 The method for growing large-size GaN single crystals by an ammonothermal method provided in this comparative example is basically the same as that in Example 1, except that the ratio of the sum of the radial areas of the remaining through holes except the central through hole to the radial area of ​​the baffle is approximately 2%.

[0051] The size of the GaN single crystal finally obtained in this comparative example is about 1.9 inches, and the defect density is about 7.1×10 6 / cm 2 The surface is smooth and flat, and the doping concentrations of Fe and Si are about 3.3×10 18 / cm 3 , about 5.6×10 19 / cm 3 , the Si element is evenly distributed in the GaN single crystal, while the Fe element is unevenly distributed in the GaN single crystal.

[0052] Comparative Example 4 The method for growing large-size GaN single crystals by the ammonothermal method provided in this comparative example is basically the same as that in Example 1, except that the ratio of the sum of the radial areas of the remaining through holes except the central through hole to the radial area of ​​the baffle is approximately 22%.

[0053] The GaN crystal finally obtained in this comparative example contains part of the polycrystalline phase, has a size of about 1.1 inches, and a defect density of about 5.8×10 8 / cm 2There are many tiny pits and cracks randomly distributed on the surface, and the doping concentrations of Fe and Si are about 5.2×10 17 / cm 3 , about 3.8×10 18 / cm 3 , Fe and Si elements are unevenly distributed in GaN single crystals.

[0054] Comparative Example 5 The method for growing a large-sized GaN single crystal by an ammonothermal method provided in this comparative example is basically the same as that in Example 1, except that the seed crystal used is a cubic seed crystal with a size of 10 mm×10 mm.

[0055] The size of the GaN single crystal finally obtained in this comparative example is about 1.6 inches, and the defect density is about 3×10 5 / cm 2 The surface is smooth and the doping concentration of Fe element is about 2.3×10 18 / cm 3 , the doping concentration of Si element is about 1.7×10 19 / cm 3 , and the Si element is evenly distributed in the GaN single crystal, while the distribution of the Fe element is less uniform.

[0056] Example 2 The method for growing a large-sized GaN single crystal by an ammonothermal method provided in this embodiment is basically the same as that in embodiment 1, except that: in step (1) of this embodiment, the GaN single crystal obtained in embodiment 1 is cut into c-plane elongated GaN wafers with a size of about 50 mm×10 mm×1 mm as seed crystals.

[0057] The size and composition of the GaN single crystal finally obtained in this embodiment are similar to those of the product in Example 1.

[0058] Example 3 A method for growing a large-size GaN single crystal by an ammonothermal method comprises the following steps: (1) A high-pressure reactor is selected as a reactor, and in an inert atmosphere glove box, a polycrystalline raw material containing doping elements and a mineralizer are filled into the raw material area of ​​the reactor, wherein the polycrystalline raw material containing doping elements is a powder, the average particle size of the powder particles is about 3 mm, and the concentration of the doped element is about 2.9×10 19 / cm 3 The Fe element concentration is about 5.3×10 18 / cm 3 The Ce element and concentration are about 4.9×10 20 / cm 3Si element, ammonium iodide is selected as the mineralizer. Also, a c-plane elongated GaN seed crystal with a size of about 50mm×10mm×0.3mm is suspended in the growth zone in the reactor through a silver wire. The growth zone is located above the raw material zone, and the raw material zone and the growth zone are separated by a molybdenum baffle with through holes. The baffle is provided with a plurality of through holes penetrating the baffle in the thickness direction, one of which is arranged at the center of the baffle, and the other through holes are symmetrically arranged on the baffle, and the apertures of the plurality of through holes decrease in sequence from the center to the edge of the baffle, and the ratio of the radial area of ​​the through hole at the center of the baffle to the radial area of ​​the baffle is about 0.6%, and the ratio of the sum of the radial areas of the other through holes to the radial area of ​​the baffle is about 15%, and these through holes can all be diamond through holes. Then, liquid ammonia is injected into the reactor, and the filling degree is about 70%, and the reactor is sealed.

[0059] (2) The reactor loaded with polycrystalline raw materials, mineralizers and liquid ammonia was placed in a vertical tube furnace with two temperature zones for heating. The temperature of the temperature zone corresponding to the raw material zone was set to about 650°C, and the temperature of the temperature zone corresponding to the growth zone was set to about 530°C. The growth pressure was controlled to about 300 MPa, and the growth time was about 15 days to obtain a GaN single crystal with a diameter of about 2.2 inches and a defect density of about 2.5×10 4 / cm 2 The surface is smooth and flat, and the doping concentrations of Fe, Ce, and Si are 2.5×10 18 / cm 3 4.1×10 17 / cm 3 , 3.4×10 19 / cm 3 About, and Fe, Ce, and Si elements are evenly distributed in the GaN single crystal.

[0060] Example 4 The method for growing a large-size GaN single crystal by an ammonothermal method provided in this embodiment is basically the same as that in Embodiment 3, except that: The polycrystalline raw material containing doping elements used in step (1) contains a concentration of about 4.4×10 18 / cm 3 The C element has a concentration of about 1.7×10 18 / cm 3 The Ti element and concentration are about 3.6×10 20 / cm 3 Si element, NaNH2 is used as the mineralizer.

[0061] In step (2), the temperature of the raw material zone is set to about 650°C, and the temperature of the growth zone is set to about 600°C.

[0062] The diameter of the GaN single crystal finally obtained in this embodiment is about 2.1 inches, and the defect density is about 1.3×10 4 / cm 2 The surface is smooth and flat, and the doping concentrations of C, Ti, and Si are 3.0×10 17 / cm 3 , 1.9×10 17 / cm 3 , 5.2×10 19 / cm 3 About, and C, Ti, and Si elements are evenly distributed in the GaN single crystal.

[0063] Although the present application has been described with reference to illustrative embodiments, it will be appreciated by those skilled in the art that various other changes, omissions, and / or additions may be made and that elements of the described embodiments may be substituted with substantial equivalents without departing from the spirit and scope of the present application. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present application without departing from the scope of the present application. Therefore, it is not intended herein to limit the present application to the disclosed specific embodiments for carrying out the present application, but rather it is intended that the present application will include all embodiments within the scope of the appended claims.

Claims

1. A liquid phase growth and doping method for large-size nitride crystals, characterized in that: include: Placing a gallium nitride polycrystalline raw material containing doping elements and a mineralizer into a raw material area in a reactor, and placing a gallium nitride seed crystal into a growth area in the reactor, and separating the raw material area from the growth area with a baffle, wherein the baffle has a through hole and / or a gap is left between the edge of the baffle and the inner wall of the reactor, and the through hole and / or the gap are used to connect the raw material area with the growth area; Then, the reactor is filled with a liquid reaction medium and the reactor is sealed; Then, the temperatures of the raw material area and the growth area are set to a first temperature and a second temperature respectively, wherein the first temperature is higher than the second temperature, so as to grow and obtain a gallium nitride single crystal.

2. The liquid phase growth and doping method of large-size nitride crystals according to claim 1, characterized in that: The doping element includes one or more combinations of Si, Ge, Mg, Zn, Fe or rare earth elements; And / or, the doping concentration of the doping element in the gallium nitride polycrystalline raw material is 10 17 -10 20 / cm 3 .

3. The liquid phase growth and doping method of large-size nitride crystals according to claim 1, characterized in that: The gallium nitride polycrystalline raw material is powder, and the particle size is 1-10 mm.

4. The liquid phase growth and doping method of large-size nitride crystals according to claim 1, characterized in that: The through hole is opened at the center of the baffle, and the ratio of the area of ​​the through hole in the radial direction to the area of ​​the baffle in the radial direction is less than 1%, Alternatively, the baffle is provided with a plurality of through holes, one of which is arranged at the center of the baffle, and the remaining through holes are symmetrically arranged on the baffle, and the apertures of the plurality of through holes decrease in sequence from the center to the edge of the baffle, the ratio of the radial area of ​​the through hole located at the center of the baffle to the radial area of ​​the baffle is less than 1%, and the ratio of the sum of the radial areas of the remaining through holes to the radial area of ​​the baffle is 3%-20%; And / or, the baffle is made of an inert material.

5. The liquid phase growth and doping method of large-size nitride crystals according to claim 1, characterized in that: There are multiple growth zones and multiple baffles, and the multiple growth zones and raw material zones are distributed in sequence along a set direction, wherein the baffles are also arranged between adjacent growth zones.

6. The liquid phase growth and doping method of large-size nitride crystals according to claim 1, characterized in that: The filling degree of the liquid reaction medium in the reactor is 60%-70%; and / or the liquid reaction medium comprises liquid ammonia.

7. The liquid phase growth and doping method of large-size nitride crystals according to claim 1, characterized in that: include: S1, selecting a first long strip-shaped GaN wafer as the gallium nitride seed crystal to grow a first gallium nitride single crystal; S2, cutting the first gallium nitride single crystal to obtain a second long-strip GaN wafer, wherein the overall size of the second GaN wafer is larger than that of the first GaN wafer; S3, using the second GaN wafer as the gallium nitride seed crystal to grow a second gallium nitride single crystal, wherein the overall size of the second gallium nitride single crystal is greater than that of the first gallium nitride single crystal; Repeat the operations of S1 to S3 one or more times until a gallium nitride single crystal having a predetermined size is obtained.

8. The liquid phase growth and doping method of large-size nitride crystals according to any one of claims 1 and 7, characterized in that: The gallium nitride seed crystal is a c-plane long strip seed crystal; and / or, during the process of growing the gallium nitride single crystal, GaN preferentially grows along the a direction of the crystal.

9. The liquid phase growth and doping method of large-size nitride crystals according to claim 1, characterized in that: Specifically include: The temperatures of the raw material zone and the growth zone are set to 500-650° C. and 400-650° C. respectively, and the growth pressure is set to 200 MPa-300 MPa and the growth time is set to 14-100 days, so as to grow and form the gallium nitride single crystal.

10. The liquid phase growth and doping method of large-size nitride crystals according to claim 1, characterized in that: The nitride crystal is a gallium nitride single crystal, and its dislocation density is less than 5×10 -3 cm -2 .

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