CN115012040A - Method for preparing large-size nitride object single crystal by using single crystal two-dimensional material - Google Patents

Abstract

The invention discloses a method for preparing a single crystal of a large-sized nitrided object by using a single crystal two-dimensional material. The invention uses splicing polycrystalline nitride elements to obtain a carrier nitride substrate, prepares a single crystal expansion layer and a single crystal cut-off layer on the two-dimensional material transferred from the upper and lower surfaces thereof, and induces induction from single crystal AlN by constructing a high temperature and high pressure temperature gradient field. The single crystallization process from the bulk to the entire nitride structure can prepare large-scale nitride single crystals with a thickness of centimeter-level or more than 100 microns in diameter, and prepare single crystals of different nitrides such as GaN or AlN. The crystal AlN inducer induces recrystallization, which can obtain a nitrided object single crystal with extremely high crystal quality, and the process is less difficult and suitable for mass production; the invention is suitable for the preparation industry of nitride semiconductor single crystal substrates, and nitrided object single crystal cutting Afterwards, it can be used as a substrate for the manufacture of high-performance light-emitting devices and electronic devices, and has important applications in the fields of laser lighting, radio frequency communication, and the like.

Description

A method for preparing large-sized single crystals of nitrided objects using single-crystal two-dimensional materials

technical field

The present invention relates to compound semiconductor single crystal preparation technology, in particular to a method for preparing large-sized nitrided object single crystal by using single crystal two-dimensional material.

Background technique

Wurtzite structure nitrides represented by aluminum nitride (AlN) and gallium nitride (GaN) have the characteristics of large forbidden band width, high thermal conductivity, high breakdown field strength, and high acoustic wave propagation speed. The best substrate material for light-emitting devices, high-frequency and high-power electronic devices, etc., has important applications in the fields of ultraviolet disinfection, 5G communication, fine processing, and high-density storage.

GaN and AlN have high melting temperature and high decomposition pressure, so they can only be prepared artificially under non-equilibrium or high pressure conditions. At this stage, the industry mainly adopts two technical solutions of hydride vapor deposition or physical vapor transport for the preparation of nitride single crystals for substrates. Among them, the hydride vapor deposition technical scheme mainly uses a micron-thick single-crystal GaN film deposited on a single-crystal sapphire substrate as a template, and then epitaxially prepares and peels off a single-crystal GaN thick film with a thickness of 100 microns. After grinding and polishing, a single crystal GaN film is obtained. Sheet GaN single crystal substrates, with a typical size of about 50 mm and a typical dislocation density greater than 1×10 ⁶ cm ^-2 , have problems of small size, poor quality, low yield and high cost; the main technical solutions for physical vapor transport are Small-sized AlN crystals or AlN single crystal substrates obtained by spontaneous nucleation and growth are used as seed crystals, and single crystal AlN blocks with a thickness of millimeters or centimeters are obtained by crystal expansion. After cutting, grinding and polishing, multiple pieces of AlN single crystal substrates are obtained. Its typical size is about 60 mm, and the typical dislocation density is about 5×10 ⁴ cm ^-2 . There are problems such as small size, low yield, high technological difficulty and high equipment requirements.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned deficiencies of the prior art, the present invention proposes a method for preparing a single crystal of a large-sized nitrided object by using a single-crystal two-dimensional material. The single-crystal expansion layer and single-crystal cut-off layer on the two-dimensional material are induced to be single-crystallized from the single-crystal AlN inducer to the entire nitride structure by constructing a high-temperature and high-pressure temperature gradient field.

The method for preparing a single crystal of a large-sized nitrided object by using a single-crystal two-dimensional material of the present invention comprises the following steps:

1) Preparation of carrier nitride substrate:

a) providing a carrier substrate and a plurality of hexagonal prism-shaped polycrystalline nitride units with the same size, and closely arranging the plurality of polycrystalline nitride units on the carrier substrate;

b) Fill the gap between the side walls of adjacent polycrystalline nitride units with boron oxynitride powder, the filling height is the same as the height of the polycrystalline nitride unit, and heat to form boron oxynitride compounds, so that adjacent The polycrystalline nitride primitives are tightly connected by boron, oxygen and nitrogen compounds, so that a plurality of closely arranged polycrystalline nitride primitives are spliced together on the carrier substrate to form a whole;

c) Remove the carrier substrate to obtain a polycrystalline nitride substrate formed by splicing a plurality of polycrystalline nitride elements, and deposit an upper nitride cap layer and a lower nitride cap on the upper and lower surfaces of the polycrystalline nitride substrate, respectively. layer, covering the upper surface and the lower surface of the polycrystalline nitride substrate, and depositing a sidewall nitride cap layer on the sidewall of the polycrystalline nitride substrate to obtain a carrier nitride substrate;

2) Preparation of single crystal expansion layer:

a) The first single crystal h-BN thin layer of hexagonal layered structure, the first single crystal BAlN thin layer of wurtzite structure, and the first single crystal BAlN thin layer of wurtzite structure were sequentially transferred on the upper nitride cap layer of the carrier nitride substrate. the first single crystal AlN thin layer;

b) High temperature annealing, so that the first single crystal h-BN thin layer and the upper surface of the carrier nitride substrate are connected by van der Waals force at the interface, and at the interface between the first single crystal h-BN thin layer and the first single crystal BAlN thin layer The mixed van der Waals force and covalent bond are used for connection, and the interface between the first single crystal BAlN thin layer and the first single crystal AlN thin film is connected by covalent bond to realize the upper surface of the carrier nitride substrate, the first single crystal h- The interlayer fastening of the BN thin layer, the first single crystal BAlN thin layer and the first single crystal AlN thin layer;

c) Growth of the first single crystal AlN induction layer, the first single crystal h-BN thin layer, the first single crystal BAlN thin layer and the first single crystal AlN thin layer and the first single crystal thin layer on the first single crystal AlN thin layer The AlN induction layer constitutes a single crystal expansion layer;

3) Preparation of reconstituted carrier nitride substrate:

a) Using ultraviolet laser etching technology to remove the boron oxynitride compound in the gap between the lower nitride cap layer and the adjacent polycrystalline nitride element;

b) The gap between adjacent polycrystalline nitride elements is refilled with polycrystalline nitride powder with the same composition as the polycrystalline nitride element, and the adjacent polycrystalline nitride powder is fused by melting and agglomerating the polycrystalline nitride powder. Nitride element and polycrystalline nitride element are formed into a whole through polycrystalline nitride powder welding to obtain a reconstructed carrier nitride substrate, and the lower surface is ground and polished to make the lower surface flat, dense, continuous and uniform;

4) Preparation of single crystal cut-off layer:

a) The second single-crystal h-BN thin layer with hexagonal layered structure, the second single-crystal BAlN thin layer with wurtzite structure, and the second single-crystal BAlN thin layer with wurtzite structure are sequentially aligned and transferred on the lower surface of the reconstructed carrier nitride substrate. Two single crystal AlN thin layers;

b) High temperature annealing, so that the second single crystal h-BN thin layer and the lower surface of the reconstructed carrier nitride substrate are connected by van der Waals force at the interface, and the second single crystal h-BN thin layer and the second single crystal BAlN thin layer are connected The mixed van der Waals forces and covalent bonds are used at the interface, and the second single crystal BAlN thin layer and the second single crystal AlN thin layer are connected by covalent bonds at the interface, so as to realize the reconstruction of the lower surface of the carrier nitride substrate , the interlayer fastening of the second single crystal h-BN thin layer, the second single crystal BAlN thin layer and the second single crystal AlN thin layer;

c) Growth of the second single crystal AlN induction layer, the second single crystal h-BN thin layer, the second single crystal BAlN thin layer, the second single crystal AlN thin layer and the second single crystal thin layer on the second single crystal AlN thin layer The AlN induction layer constitutes a single crystal cut-off layer;

5) Obtain a single crystal of nitrided object:

a) splicing the single crystal AlN inducer at the center of the upper surface of the first single crystal AlN inducer layer;

b) Build a high temperature and high pressure temperature gradient field to drive the recrystallization from the single crystal AlN inducer to the single crystal cutoff layer, so that the entire nitride structure from the single crystal extension layer to the single crystal cutoff layer has the same as the single crystal AlN inducer. The lattice is arranged to obtain a single crystal of a nitrided object.

Wherein, in a) of step 1), the material of the carrier substrate is one of titanium, nickel, copper and iron; the material of the polycrystalline nitride element is AlN, GaN, AlGaN, BN, BAlN, BGaN or For ScAlN, in order to be compatible with large-scale expansion, the hexagonal side length of the bottom surface of the hexagonal prism of the polycrystalline nitride unit is greater than 20 mm, and the thickness is greater than 1 mm; each polycrystalline nitride unit is connected to the adjacent polycrystalline nitride. The corresponding side walls of the primitives are aligned, and the spacing between adjacent side walls is less than 0.2 mm. The area of the carrier substrate is greater than the total area of the closely packed plurality of polycrystalline nitride cells.

In b) of step 1), the boron oxygen nitrogen powder is a mixed powder of boron nitride and boron oxide, the molar ratio of boron nitride and boron oxide is 1:2~2:1, and the temperature is 500 ℃~800 ℃ The boron oxynitride compound is formed by heat treatment in the temperature range, and the boron oxynitride compound connects the adjacent polycrystalline nitride units to form a whole, that is, the boron oxynitride compound completely fills the space between the adjacent polycrystalline nitride units in the lateral dimension. The gap and longitudinal dimension are consistent with the height of each polycrystalline nitride unit, and the polycrystalline nitride substrate with a flat upper surface.

In c) of step 1), the carrier substrate under the integrated polycrystalline nitride element is removed by room temperature chemical etching or mechanical stripping method, wherein the room temperature chemical etching adopts hydrochloric acid solution, ferric chloride solution or ammonium sulfate solution ; Then, 100 nm to 1000 nm thick polycrystalline AlN was deposited sequentially on the upper and lower surfaces of the polycrystalline nitride block by pulsed laser deposition, physical vapor deposition, or magnetron sputtering to form upper and lower nitride caps, respectively Finally, 10 μm~50 μm polycrystalline AlN is deposited on the sidewall of the polycrystalline nitride element by physical vapor deposition, magnetron sputtering, etc., to form a sidewall nitride cap layer.

In a) of step 2), the first single crystal h-BN thin layer has a hexagonal layered structure, is a two-dimensional material, and has a thickness of 1-10 nm, which is used to cover the surface of the upper nitride capping layer; the first single crystal The BAlN thin film is used to realize the transition from the first single crystal h-BN thin layer to the upper first single crystal AlN thin layer, with a wurtzite structure, a thickness of 5~20 nm, and a B composition of less than 15%; A single-crystal AlN film with a wurtzite structure with a thickness of 10–100 nm serves as a template layer for subsequent single-crystal nitride epitaxy.

In b) of step 2), in a temperature range of 1000-1700 °C, a pressure range of 10-1000 Pa, and a high-temperature annealing treatment under nitrogen atmosphere for 10-100 min. The first single-crystal h-BN thin layer, the first single-crystal BAlN thin layer, and the first single-crystal AlN thin layer after the interlayer fastening is realized constitute the first interface BAlN functional layer, and the first interface BAlN functional layer is used for shielding The polycrystalline structure of the lower layer realizes the transition from the underlying polycrystalline structure to the single crystal structure, and provides the required growth interface for the epitaxy of the first single crystal AlN induction layer of the upper layer.

In c) of step 2), metal organic chemical vapor deposition, molecular beam epitaxy or pulsed laser deposition or hydride vapor phase epitaxy is used on the upper surface of the first single crystal AlN thin layer to deposit 100~ The 1000 μm thick first single crystal AlN induced layer, the dislocation density of the first single crystal AlN induced layer near the upper surface is lower than 1×10 ⁶ cm ^-2 .

In a) of step 3), the ultraviolet laser etching technology uses an ultraviolet laser with a wavelength shorter than 200 nm to etch the lower nitride cap layer and the gap in the adjacent polycrystalline nitride element under the condition of no mask. Boron oxynitride compound.

In b) of step 3), the polycrystalline nitride powder is melted and agglomerated at a temperature range of 1050-1700 °C, under a normal pressure nitrogen atmosphere, and annealed for 30-90 min, so that the polycrystalline nitride powder is melted And fill the gaps between adjacent polycrystalline nitride units, and solidify and connect the sidewalls of adjacent polycrystalline nitride units after cooling down.

In a) of step 4), the second single-crystal h-BN thin layer has a hexagonal layered structure, is a two-dimensional material, and has a thickness of 1-10 nm, which is used to cover the reconstructed carrier nitride substrate with a polycrystalline structure. The lower surface; the second single crystal BAlN thin layer has a wurtzite structure, the thickness is 5~20 nm, and the boron content is less than 15%, which is used to realize the second single crystal h-BN thin layer from the upper layer to the bottom layer. Transition of single-crystal AlN thin layer; the second single-crystal h-BN thin layer has a wurtzite structure with a thickness of 10–100 nm, serving as a template layer for subsequent single-crystal nitride epitaxy.

In b) of step 4), in the temperature range of 1000~1700 °C, the pressure range of 10~1000 Pa, under the condition of nitrogen atmosphere, high temperature annealing treatment is performed for 10~100 min. The second single-crystal h-BN thin layer, the second single-crystal BAlN thin layer and the second single-crystal AlN thin layer after the interlayer fastening is realized constitute the second interface BAlN functional layer, and the second interface BAlN functional layer is used for shielding The polycrystalline structure of the upper layer realizes the transition from the polycrystalline structure of the upper layer to the single crystal structure, and provides the required growth interface for the epitaxy of the second single crystal AlN induction layer of the lower layer.

In c) of step 4), metal-organic chemical vapor deposition, molecular beam epitaxy or pulsed laser deposition or hydride vapor phase epitaxy is used on the lower surface of the second single-crystal AlN thin layer, at a temperature range of 800-1400 °C, to deposit 5 ~20 μm thick second single crystal AlN induced layer, the dislocation density of the second single crystal AlN layer close to the surface is lower than 1×10 ⁹ cm ⁻² .

In a) of step 5), the single crystal AlN inducer is spliced and spliced at the center of the upper surface of the first single crystal AlN induction layer, which specifically includes the following steps: using an ultraviolet laser with a wavelength shorter than 200 nm to fuse the single crystal AlN The inducer is welded in the center of the upper surface of the first single crystal AlN inducer layer, the single crystal AlN inducer is aligned with the center of the first single crystal AlN inducer layer, and the single crystal AlN inducer is in-plane with the first single crystal AlN inducer layer The lattice arrangement is aligned; the shape of the single crystal AlN inducer is a cylinder, the dislocation density is lower than 2×10 ⁴ cm ^-2 , the thickness is greater than 0.1 mm, and the diameter of the bottom surface of the cylinder is less than 10 mm.

In b) of step 5), the base temperature T of the temperature gradient field is 2000~2400 °C, the thickness direction is along the Z direction, the lower surface of the single crystal cut-off layer is the zero point in the Z direction, and the single crystal cut off along the Z direction The temperature gradient DT of the layer pointing to the single crystal expansion layer is 10~100 ℃/cm, the corresponding temperature at different positions is T+DT×z, z is the position along the Z direction; the single crystal AlN inducer is resistant to high temperature, and the lattice is arranged Stable under the thermal field, the lattice arrangement is conducted downward in the temperature gradient field, the surface layer of the entire nitride structure from the single crystal expansion layer to the single crystal cut-off layer does not decompose, and the expansion from the single crystal is only caused by the temperature gradient difference. The lattice arrangement of the entire nitride structure from layer to single crystal cutoff layer expands from high temperature to low temperature, inducing the entire nitride structure from single crystal expansion layer to single crystal cutoff layer to have a single crystal AlN inducer with the highest temperature region The same lattice arrangement, that is, the temperature gradient field makes the regular lattice arrangement of the single crystal AlN inducer driven by the temperature gradient from the single crystal AlN inducer to the single crystal extension layer to the single crystal cutoff layer, that is, directional recrystallization, Eventually, a single crystal ingot of a nitrided object is formed.

Advantages of the present invention:

The invention can prepare single crystals of large-scale nitride objects with a thickness of centimeter-level and a diameter of more than 100 mm, and prepare single crystals of different nitride objects such as GaN or AlN, and induce recrystallization through ultra-high-quality single-crystal AlN inducers. The nitrided single crystal with extremely high crystal quality is obtained, the process difficulty is small, and it is suitable for mass production; the invention is suitable for the preparation industry of the nitride semiconductor single crystal substrate, and after the nitrided single crystal is cut, it can be used as a substrate for manufacturing High-performance light-emitting devices and electronic devices have important applications in the fields of laser lighting and radio frequency communications.

Description of drawings

1 is a polycrystalline nitride unit obtained according to an embodiment of the method for preparing a single crystal of a large-sized nitride object by using a single crystal two-dimensional material according to the present invention. A plurality of polycrystalline nitride units are processed on a carrier substrate close-packed top view;

2 is a cross-sectional view of forming a boron oxynitride compound according to an embodiment of the method for preparing a single crystal of a large-sized nitride object by using a single crystal two-dimensional material;

3 is a cross-sectional view of a carrier nitride substrate obtained according to an embodiment of the method for preparing a single crystal of a large-sized nitride object using a single-crystal two-dimensional material according to the present invention;

4 is a cross-sectional view of obtaining a single crystal expansion layer according to an embodiment of the method for preparing a large-sized nitrided object single crystal by using a single crystal two-dimensional material according to the present invention;

5 is a cross-sectional view of a reconstructed carrier nitride substrate obtained according to an embodiment of the method for preparing a single crystal of a large-sized nitride object using a single-crystal two-dimensional material according to the present invention;

6 is a cross-sectional view of a single crystal cut-off layer obtained according to an embodiment of the method for preparing a single crystal of a large-sized nitrided object using a single crystal two-dimensional material according to the present invention;

7 is a cross-sectional view of a single crystal of a nitrided object obtained by an embodiment of the method for preparing a single crystal of a large-sized nitrided object by using a single-crystal two-dimensional material according to the present invention.

Detailed ways

Below in conjunction with the accompanying drawings, the present invention will be further described through specific embodiments.

The method for preparing a single crystal of a large-sized nitrided object by using a single-crystal two-dimensional material in this embodiment includes the following steps:

1) Preparation of carrier nitride substrate:

a) Provide a carrier substrate 2 made of copper, and a plurality of hexagonal prismatic polycrystalline nitride cells 1 of the same size, made of AlN, the bottom hexagon with a side length of 30 mm and a thickness of 5 mm. The polycrystalline nitride elements are closely arranged like a honeycomb on the carrier substrate, and the spacing between adjacent sidewalls is 0.15 mm, as shown in Figure 1;

b) Fill the gap between adjacent polycrystalline nitride element sidewalls with boron oxynitride powder. The ratio of boron nitride and boron oxide mixed powder is 2:3, and the filling height is the same as that of the polycrystalline nitride element. The height of the elements is consistent, and the boron oxynitride compound 3 is formed by heating in the temperature range of 600 ℃, so that the adjacent polycrystalline nitride elements are closely connected through the boron oxynitride compound, so that a plurality of closely arranged polycrystalline nitride elements are formed. Splicing on the carrier substrate to form a whole, as shown in Figure 2;

c) Remove the carrier substrate by etching with hydrochloric acid solution to obtain a polycrystalline nitride substrate formed by splicing a plurality of polycrystalline nitrides. The nitride capping layer 41 and the lower nitride capping layer 42 cover the upper surface and the lower surface of the polycrystalline nitride substrate, and a sidewall nitride capping layer 5 of 20 μm is deposited on the sidewall of the polycrystalline nitride substrate to obtain a carrier Nitride substrate, as shown in Figure 3;

2) Preparation of single crystal expansion layer:

a) A 5 nm thick first single crystal h-BN thin layer 6, a 10 nm thick first single crystal BAlN thin layer with a B composition of 10% were sequentially transferred on the upper nitride cap layer of the carrier nitride substrate 7 and 50 nm thick first single crystal AlN thin layer 8;

b) High temperature annealing treatment at 1700 ℃, 1000 Pa, nitrogen atmosphere for 60 min, so that the first single crystal h-BN thin layer and the upper surface of the carrier nitride substrate are connected by van der Waals force at the interface, the first single crystal h-BN -The interface between the BN thin layer and the first single crystal BAlN thin layer is connected by mixed van der Waals forces and covalent bonds, and the interface between the first single crystal BAlN thin layer and the first single crystal AlN thin layer is connected by covalent bonds to realize the carrier The upper surface of the nitride substrate, the first single crystal h-BN thin layer, the first single crystal BAlN thin layer, and the first single crystal AlN thin layer are tightly bonded between layers, so as to realize the first single crystal after the tight bonding between the layers. The crystalline h-BN thin layer, the first single crystal BAlN thin layer and the first single crystal AlN thin layer constitute the first interface BAlN functional layer;

c) A 500 μm-thick first single-crystal AlN induction layer 9 was grown on the first single-crystal AlN thin layer of the first interface BAlN functional layer at a temperature of 1200 °C by hydride vapor phase epitaxy, and the first interface BAlN functional layer and the first single crystal AlN induced layer to form a single crystal extension layer, and the dislocation density of the single crystal AlN near the upper surface is 9.5×10 ⁵ cm ^-2 , as shown in Fig. 4 ;

3) Preparation of reconstituted carrier nitride substrate:

a) Using UV laser etching technology with a wavelength of 177 nm, incident from the lower surface of the carrier nitride substrate, without masking, to remove the boron-oxygen in the gap between the lower nitride cap layer and the adjacent polycrystalline nitride element nitrogen compounds;

b) The gaps of adjacent polycrystalline nitride elements are refilled with polycrystalline nitride powder AlN with the same composition as the polycrystalline nitride element, and annealed for 60 min at 1700 ℃ in a normal pressure nitrogen atmosphere to melt the The polycrystalline nitride powder is condensed, and the adjacent polycrystalline nitride elements are welded, and the polycrystalline nitride element is formed into a whole by welding the polycrystalline nitride powder to obtain a reconstructed carrier nitride substrate 10. Grinding and polishing is performed to make the lower surface flat, dense and continuous, as shown in Figure 5;

4) Preparation of single crystal cut-off layer:

a) A 5 nm-thick second single-crystal h-BN thin layer 11, 10 nm-thick second single-crystal BAlN thin layer 12 with a B composition of 10% are sequentially aligned and transferred on the lower surface of the reconstituted carrier nitride substrate and 50 nm thick second single crystal AlN thin layer 13;

b) High temperature annealing at 1700 ℃, 1000 Pa, nitrogen atmosphere for 60 min, so that the second single crystal h-BN thin layer and the lower surface of the reconstructed carrier nitride substrate are connected by van der Waals force at the interface, and the second single crystal h-BN thin layer and the lower surface of the reconstructed carrier nitride substrate are connected by van der Waals The crystalline h-BN thin layer and the second single crystal BAlN thin layer are connected by mixed van der Waals forces and covalent bonds at the interface, and the second single crystal BAlN thin layer and the second single crystal AlN thin layer are connected at the interface by covalent bonding. Valence bond connection to realize the interlayer tight bonding of the lower surface of the reconstructed carrier nitride substrate, the second single crystal h-BN thin layer, the second single crystal BAlN thin layer and the second single crystal AlN thin layer to realize the interlayer The second single crystal h-BN thin layer, the second single crystal BAlN thin layer and the second single crystal AlN thin layer after the fastening and bonding constitute the second interface BAlN functional layer;

c) A 5 μm-thick second single-crystal AlN induction layer 14 was grown on the second single-crystal AlN thin layer of the second interface BAlN functional layer at a temperature of 1200 °C by hydride vapor phase epitaxy, close to the single crystal on the lower surface The dislocation density of AlN is 5.0×10 ⁸ cm ^-2 , and the second interface BAlN functional layer and the second single crystal AlN induced layer constitute the single crystal cutoff layer, as shown in Fig. 6 ;

5) Obtain a single crystal of nitrided object:

a) Using an ultraviolet laser with a wavelength of 177 nm, 15 pairs of single crystal AlN inducers were spliced to the center of the upper surface of the first single crystal AlN induced layer, and the single crystal AlN inducer was aligned with the center of the single crystal AlN induced layer, The single-crystal AlN inducer is aligned with the in-plane lattice arrangement of the single-crystal AlN-induced layer, where the single-crystal AlN inducer is cylindrical in shape with a dislocation density of 1×10 ⁴ cm ^-2 , a thickness of 0.2 mm, and a cylinder 1 mm in diameter;

b) Construct a high temperature and high pressure temperature gradient field. The basic temperature T of the temperature gradient field is 2200 °C, the thickness direction is along the Z direction, and the lower surface of the single crystal cut-off layer is taken as the zero point in the Z direction, that is, the temperature of the lower surface of the single crystal cut-off layer. is 2200 °C, the temperature gradient DT from the single crystal cut-off layer to the single crystal expansion layer along the Z direction is 80 °C/cm, the corresponding temperature at different positions is T+DT×z, z is the position along the Z direction; The crystal AlN inducer is resistant to high temperature, the lattice arrangement is stable under the thermal field, the lattice arrangement is conducted downward in the temperature gradient field, and the surface layer of the entire nitride structure from the single crystal extension layer to the single crystal cut-off layer does not decompose, Only through the temperature gradient difference, the lattice arrangement of the entire nitride structure from the single crystal expansion layer to the single crystal cutoff layer is expanded from the high temperature to the low temperature, and the entire nitride structure from the single crystal expansion layer to the single crystal cutoff layer is induced to have The same lattice arrangement as the single crystal AlN inducer in the highest temperature region, that is, the temperature gradient field makes the regular lattice arrangement of the single crystal AlN inducer point from the single crystal AlN inducer to the single crystal extension layer driven by the temperature gradient The single-crystal cut-off layer, ie, directional recrystallization, yields a high-quality single-crystal bulk of nitrided objects with a dislocation density not higher than 2×10 ⁴ cm ⁻² , as shown in FIG. 7 .

Finally, it should be noted that the purpose of publishing the embodiments is to help further understanding of the present invention, but those skilled in the art can understand that various replacements and modifications can be made without departing from the spirit and scope of the present invention and the appended claims. It is possible. Therefore, the present invention should not be limited to the contents disclosed in the embodiments, and the scope of protection of the present invention shall be subject to the scope defined by the claims.

Claims (10)

1. A method for preparing a large-sized single crystal of a nitrided object using a single-crystal two-dimensional material, the method comprising the steps of:

1) preparing a carrier nitride substrate:

a) providing a carrier substrate and a plurality of hexagonal prism-shaped polycrystalline nitride elements with the same size, and closely arranging the plurality of polycrystalline nitride elements on the carrier substrate;

b) filling boron-oxygen-nitrogen powder in gaps between the side walls of the adjacent polycrystalline nitride elements, wherein the filling height is consistent with the height of the polycrystalline nitride elements, heating to form boron-oxygen-nitrogen compounds, so that the adjacent polycrystalline nitride elements are tightly connected through the boron-oxygen-nitrogen compounds, and a plurality of tightly arranged polycrystalline nitride elements are spliced on the bearing substrate to form a whole;

c) removing the bearing substrate to obtain a polycrystalline nitride substrate formed by splicing a plurality of polycrystalline nitride elements into a whole, respectively depositing an upper nitride cover layer and a lower nitride cover layer on the upper surface and the lower surface of the polycrystalline nitride substrate, covering the upper surface and the lower surface of the polycrystalline nitride substrate, and depositing a side wall nitride cover layer on the side wall of the polycrystalline nitride substrate to obtain a carrier nitride substrate;

2) preparing a single crystal expansion layer:

a) sequentially transferring a first single crystal h-BN thin layer with a hexagonal layered structure, a first single crystal BAlN thin layer with a wurtzite structure and a first single crystal AlN thin layer with a wurtzite structure on an upper nitride cover layer of a carrier nitride substrate;

b) high-temperature annealing is carried out, so that the first single crystal h-BN thin layer is connected with the upper surface of the carrier nitride substrate by Van der Waals force at the interface, the first single crystal h-BN thin layer is connected with the first single crystal BAlN thin layer by mixed Van der Waals force and covalent bonds at the interface, and the first single crystal BAlN thin layer is connected with the first single crystal AlN thin layer by covalent bonds at the interface, so that interlayer fastening combination of the upper surface of the carrier nitride substrate, the first single crystal h-BN thin layer, the first single crystal BAlN thin layer and the first single crystal AlN thin layer is realized;

c) growing a first monocrystal AlN induction layer on the first monocrystal AlN thin layer, wherein the first monocrystal h-BN thin layer, the first monocrystal BAlN thin layer, the first monocrystal AlN thin layer and the first monocrystal AlN induction layer form a monocrystal expansion layer;

3) preparing a reconstructed carrier nitride substrate:

a) removing boron-oxygen nitride compounds in gaps between the lower nitride cap layer and the adjacent polycrystalline nitride elements by adopting an ultraviolet laser etching technology;

b) filling polycrystalline nitride powder with the same components as the polycrystalline nitride elements again at the gaps of the adjacent polycrystalline nitride elements, fusing the adjacent polycrystalline nitride elements by melting and condensing the polycrystalline nitride powder, fusing the polycrystalline nitride elements into a whole by fusing the polycrystalline nitride powder to obtain a reconstructed carrier nitride substrate, and grinding and polishing the lower surface to enable the lower surface to be flat, compact, continuous and uniform;

4) preparing a single crystal cut-off layer:

a) sequentially aligning and transferring a second single crystal h-BN thin layer with a hexagonal layered structure, a second single crystal BAlN thin layer with a wurtzite structure and a second single crystal AlN thin layer with the wurtzite structure on the lower surface of the reconstructed carrier nitride substrate;

b) high-temperature annealing is carried out, so that the second single crystal h-BN thin layer is connected with the lower surface of the reconstructed carrier nitride substrate by Van der Waals force at the interface, the second single crystal h-BN thin layer is connected with the second single crystal BAlN thin layer by mixed Van der Waals force and covalent bonds at the interface, and the second single crystal BAlN thin layer is connected with the second single crystal AlN thin layer by covalent bonds at the interface, and interlayer fastening combination of the lower surface of the reconstructed carrier nitride substrate, the second single crystal h-BN thin layer, the second single crystal BAlN thin layer and the second single crystal AlN thin layer is realized;

c) growing a second monocrystal AlN induction layer on the second monocrystal AlN thin layer, wherein the second monocrystal h-BN thin layer, the second monocrystal BALN thin layer, the second monocrystal AlN thin layer and the second monocrystal AlN induction layer form a monocrystal cut-off layer;

5) obtaining a nitride object single crystal:

a) splicing and welding a single crystal AlN inducer at the center of the upper surface of the first single crystal AlN inducer;

b) and constructing a high-temperature high-pressure temperature gradient field, and driving recrystallization from the single crystal AlN inducer to the direction of the single crystal cut-off layer, so that the whole nitride structure from the single crystal expansion layer to the single crystal cut-off layer has the same lattice arrangement as the single crystal AlN inducer, and the nitride object single crystal is obtained.

2. The method as claimed in claim 1, wherein in the step 1) a), the material of the carrier substrate is one of titanium, nickel, copper and iron; the polycrystalline nitride element is made of AlN, GaN, AlGaN, BN, BALN, BGaN or ScAlN; the side length of a hexagon on the bottom surface of the hexagonal prism of the polycrystalline nitride element is more than 20 mm, and the thickness of the hexagonal prism is more than 1 mm; each poly-nitride element is aligned with a respective sidewall of an adjacent poly-nitride element, with a spacing between adjacent sidewalls of less than 0.2 mm.

3. The method of claim 1, wherein in step 2) a) the first thin layer of single-crystal h-BN is a two-dimensional material with a thickness of 1 to 10 nm for masking the surface of the upper nitride cap layer; the thickness of the first monocrystal BAlN thin film is 5-20 nm, the boron component is less than 15%, and the first monocrystal BAlN thin film is used for realizing transition from the first monocrystal h-BN thin film to the first monocrystal AlN thin film; the thickness of the first monocrystal AlN thin film is 10-100 nm.

4. The method according to claim 1, wherein in step 2) c), a first single-crystal AlN inducing layer with a thickness of 100-1000 μm is deposited on the upper surface of the first single-crystal AlN thin layer by metal-organic chemical vapor deposition, molecular beam epitaxy, or pulsed laser deposition or hydride vapor phase epitaxy at a temperature range of 800-1400 ℃.

5. The method according to claim 1, wherein in step 3) a) the uv laser etching technique uses uv laser light with a wavelength shorter than 200 nm to etch the boron-oxygen-nitride compound in the lower nitride cap layer and the gaps between adjacent polycrystalline nitride elements without a mask.

6. The method according to claim 1, wherein in step 3) b), annealing is performed at 1050-1700 ℃ under nitrogen atmosphere at normal pressure for 30-90 min to melt the polycrystalline nitride powder and fill gaps between adjacent polycrystalline nitride elements, and the sidewall of the adjacent polycrystalline nitride elements is solidified and connected after cooling.

7. The method according to claim 1, wherein in step 4) a) the second thin layer of monocrystalline h-BN is a two-dimensional material with a thickness of 1 to 10 nm for masking the lower surface of the reconstituted carrier nitride substrate with a polycrystalline structure; the thickness of the second monocrystal BAlN thin layer is 5-20 nm, the boron component is less than 15%, and the second monocrystal BAlN thin layer is used for realizing transition from the second monocrystal h-BN thin layer on the upper layer to the second monocrystal AlN thin layer on the bottom layer; the thickness of the second monocrystal h-BN thin layer is 10-100 nm.

8. The method according to claim 1, wherein in step 4) c), a second single-crystal AlN inducing layer with a thickness of 5-20 μm is deposited on the lower surface of the second single-crystal AlN thin layer by metal-organic chemical vapor deposition, molecular beam epitaxy, or pulsed laser deposition or hydride vapor phase epitaxy at a temperature range of 800-1400 ℃.

9. The method according to claim 1, wherein in step 5) a) the single-crystal AlN inducer is butt-spliced at the center of the upper surface of the first single-crystal AlN inducer layer, comprising the specific steps of: adopting ultraviolet laser with the wavelength shorter than 200 nm to weld the single crystal AlN inductor at the center of the upper surface of the first single crystal AlN inductor layer, aligning the single crystal AlN inductor with the center of the first single crystal AlN inductor layer, and aligning the single crystal AlN inductor with the in-plane lattice arrangement of the first single crystal AlN inductor layer; whereinThe monocrystal AlN inductor is cylindrical and has dislocation density lower than 2 × 10 ⁴ cm ^-2 The thickness is more than 0.1 mm, and the diameter of the bottom surface of the cylinder is less than 10 mm.

10. The method according to claim 1, wherein in step 5) b), a base temperature T of the temperature gradient field is 2000 to 2400 ℃, a thickness direction is along a Z direction, a temperature gradient DT directed from the single crystal cut-off layer to the single crystal extension layer along the Z direction is 10 to 100 ℃/cm with a lower surface of the single crystal cut-off layer as a zero point of the Z direction, corresponding temperatures at different positions are T + DT × Z, and Z is a position along the Z direction; the single crystal AlN inducer is high-temperature resistant, the lattice arrangement is stable under a thermal field, the lattice arrangement is conducted downwards in a temperature gradient field, the surface layer of the whole nitride structure from the single crystal expansion layer to the single crystal stop layer is not decomposed, the lattice arrangement of the whole nitride structure from the single crystal expansion layer to the single crystal stop layer is expanded from a high temperature position to a low temperature position only through the temperature gradient difference, the whole nitride structure from the single crystal expansion layer to the single crystal stop layer is induced to have the same lattice arrangement as the single crystal AlN inducer in the highest temperature region, namely the temperature gradient field enables the regular lattice arrangement of the single crystal AlN inducer to point to the single crystal stop layer from the single crystal AlN inducer to the single crystal expansion layer under the driving of the temperature gradient, namely, the crystal is directionally recrystallized, and finally a single crystal block of the nitride object is formed.

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