A substrate, a method of forming a substrate, and a light emitting diode

Abstract

The application discloses a substrate, a forming method of the substrate and a light emitting diode. The substrate comprises a modification layer and a body layer. The modification layer extends from a first surface of the substrate to a second surface in a direction perpendicular to the substrate. The body layer extends from a side of the modification layer away from the first surface to the second surface. A side of the body layer away from the modification layer is formed as the second surface of the substrate. The modification layer comprises a diffusion element other than the body layer. The diffusion element can change a lattice parameter of a surface of the substrate, ensure a crystal form of the substrate unchanged, and reduce a lattice mismatch between the substrate and an epitaxial layer and a dislocation density of the epitaxial layer. The application performs annealing treatment on the substrate when forming the modification layer. Therefore, the content of doped atoms and the lattice parameter of the modification layer gradually change from the first surface to the second surface of the substrate. The lattice matching degree with the epitaxial layer is greatly improved. The problem that high temperature warping divergence is caused by excessive residual stress of the substrate is solved. The internal quantum efficiency and wavelength uniformity of the epitaxial layer are optimized.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and more specifically to a substrate, a method for forming the substrate, and a light-emitting diode. Background Technology

[0002] Light-emitting diodes (LEDs) are highly influential new products in the optoelectronics industry. They are characterized by their small size, long lifespan, rich and varied colors, and low energy consumption, and are widely used in lighting, displays, signal lights, backlights, and other fields. The core structure of an LED is an epitaxial wafer, and the fabrication of the epitaxial wafer has a significant impact on the photoelectric characteristics of the LED.

[0003] In the epitaxial growth of LEDs, due to the lack of substrate materials compatible with GaN, GaN thin films are currently mainly grown on SiC, Si, and sapphire substrates via heteroepitaxial growth. However, a significant lattice mismatch exists between the heteroepitaxial substrate and the GaN thin film, resulting in a high dislocation density and decreased crystal quality in the subsequently grown epitaxial GaN film. Therefore, resolving the lattice mismatch between the heteroepitaxial substrate and GaN has become an urgent problem to be solved. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a substrate, a method for forming the substrate, and a light-emitting diode to improve the lattice mismatch between the heterogeneous substrate and the epitaxial layer and improve the growth quality of the epitaxial layer.

[0005] To achieve the above and other related objectives, the present invention provides a substrate having a first surface and a second surface disposed opposite to each other, the substrate comprising:

[0006] The modified layer extends from the first surface of the substrate to the second surface in a direction perpendicular to the substrate;

[0007] The body layer extends from the side of the modified layer away from the first surface toward the second surface, and the side of the body layer away from the modified layer forms the second surface of the substrate.

[0008] The modified layer contains elements from the bulk layer as well as diffusion elements other than those contained in the bulk layer. The diffusion elements include at least one of Al, Ga, In, and N.

[0009] According to another aspect of the present invention, the present invention also provides a method for forming a substrate, comprising:

[0010] A substrate body is provided, the substrate body having a first surface and a second surface disposed opposite to each other;

[0011] A modified layer is formed within the substrate body, dividing the substrate into a modified layer and a body layer; the modified layer extends from the first surface of the substrate body in a direction perpendicular to the substrate body to the second surface, and the body layer extends from the side of the modified layer away from the first surface to the second surface, with the side of the body layer away from the modified layer forming the second surface of the substrate.

[0012] The modified layer contains elements from the bulk layer as well as diffusion elements other than those contained in the bulk layer. The diffusion elements include at least one of Al, Ga, In, and N.

[0013] According to another aspect of the present invention, the present invention also provides a light-emitting diode, comprising:

[0014] The substrate is the substrate described above;

[0015] The epitaxial layer comprises, sequentially from the first surface of the substrate, a first semiconductor layer, an active layer, and a second semiconductor layer.

[0016] Compared with the prior art, the substrate, the method for forming the substrate, and the light-emitting diode described in this invention have at least the following beneficial effects:

[0017] The substrate of this invention has a first surface and a second surface. The substrate includes a modified layer and a bulk layer. The modified layer extends from the first surface of the substrate towards the second surface in a direction perpendicular to the substrate. The bulk layer extends from the side of the modified layer away from the first surface towards the second surface, and the side of the bulk layer away from the modified layer forms the second surface of the substrate. The modified layer includes diffusion elements other than the substrate bulk material. These diffusion elements can change the lattice parameters of the substrate surface while maintaining the substrate's crystal form, improving the lattice matching degree between the substrate and the epitaxial layer, reducing the dislocation density in the epitaxial layer, and thereby improving the internal quantum efficiency of the light-emitting diode.

[0018] In this invention, the substrate is annealed during the formation of the modified layer. This causes the doping atomic content and lattice parameters of the modified layer to gradually change along the first to the second surface of the substrate. From the second surface to the first surface, the lattice parameters of the substrate gradually approach those of the epitaxial material, significantly improving the lattice matching between the substrate and the epitaxial layer, thereby increasing the internal quantum efficiency of the epitaxial layer. Furthermore, the annealing process during modified layer formation also reduces residual stress on the substrate during machining, thus reducing warpage at high temperatures and optimizing the wavelength uniformity of the epitaxial layer.

[0019] The substrate formation method of the present invention is used to form the above-mentioned substrate, and the light-emitting diode includes the above-mentioned substrate, and also has the above-mentioned technical effects. Attached Figure Description

[0020] Figure 1This is a schematic diagram of the substrate structure in Embodiment 1 or 2 of the present invention;

[0021] Figure 2 This is a schematic diagram of the substrate body in Embodiment 1 or 2 of the present invention;

[0022] Figure 3 This is a schematic diagram of the structure after coating the substrate with a film layer in Embodiment 2 of the present invention;

[0023] Figure 4 This is a graph showing the change in elemental content in the modified layer of the substrate in Embodiment 1 or 2 of the present invention;

[0024] Figure 5 This is a schematic diagram showing the change in element content in the modified layer of the substrate and the lattice mismatch between the substrate and the epitaxial layer with the element diffusion depth in Embodiment 1 or 2 of the present invention.

[0025] Figure 6 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 3 of the present invention.

[0026] List of reference numerals in the attached diagram:

[0027] 001 Substrate Body

[0028] 002 Coating layer

[0029] 100 substrate

[0030] 110 First Surface

[0031] 120 Second Surface

[0032] 101 Modified Layer

[0033] 102 Body Layer

[0034] 200 Undoped layer

[0035] 300 epitaxial layer

[0036] 301 First Semiconductor Layer

[0037] 302 Active Layer

[0038] 303 Second Semiconductor Layer

[0039] 401 First Electrode

[0040] 402 Second Electrode Detailed Implementation

[0041] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0042] It should be understood that the illustrations provided in the embodiments of this invention are merely schematic representations of the basic concept of the invention. Although the illustrations only show components relevant to the invention and are not drawn according to the actual number, shape, and size of components in implementation, the shape, quantity, and proportion of each component can be arbitrarily changed in actual implementation, and the component layout may also be more complex. The structures, proportions, sizes, etc., shown in the accompanying drawings are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives that the invention can produce, should still fall within the scope of the technical content disclosed in this application.

[0043] In existing technologies, the lattice mismatch between the sapphire substrate and the gallium nitride epitaxial layer is relatively high (16%), resulting in a high dislocation density in the epitaxial layer and a low internal quantum efficiency of the LED chip. Furthermore, the inventors discovered that during epitaxial growth, significant stress accumulates at the interface between the substrate and the epitaxial layer. Combined with the residual stress of the substrate itself, the stress at the interface is even greater, leading to severe substrate warping. Severe substrate warping results in uneven thermal contact with the graphite disk, causing excessive temperature differences across various locations within the substrate surface. This leads to varying In content at different locations in the subsequently formed epitaxial layer, resulting in differences in the bandgap width of the corresponding quantum well, ultimately affecting the uniformity of the epitaxial wavelength. For example, in a 4-inch LED chip, the standard deviation of the wavelength for all chips within this 4-inch substrate ranges from 1.5 nm to 3 nm.

[0044] To address the problems in the background art and the aforementioned technical issues, this embodiment provides a substrate, a method for forming the substrate, and a light-emitting diode.

[0045] Specifically, this embodiment provides a substrate having a first surface and a second surface disposed opposite to each other, the substrate comprising:

[0046] The modified layer extends from the first surface of the substrate to the second surface in a direction perpendicular to the substrate;

[0047] The body layer extends from the side of the modified layer away from the first surface toward the second surface, and the side of the body layer away from the modified layer forms the second surface of the substrate.

[0048] The modified layer includes elements from the bulk layer as well as diffusion elements other than those in the bulk layer. The diffusion elements include at least one of Al, Ga, In, and N. In this embodiment, any one of Al, Ga, In, and N is diffused into the substrate. Elements with different atomic radii can change the lattice constant of the first surface of the substrate, thereby improving the lattice mismatch problem between the epitaxial layer subsequently formed on the first surface of the substrate and the substrate. Furthermore, when forming the epitaxial layer, it is directly formed on the modified layer of the substrate without the need for additional lattice mismatch buffer layers, which is beneficial for improving production efficiency.

[0049] Optionally, the thickness of the modified layer is between 100 nm and 1000 nm.

[0050] Optionally, the material of the modified layer is (Al) 1-x-y Ga x In y )2(O 1-z N z )3, where z≥x+y, 0≤x, 0≤y. In this embodiment, the proportion of elements in the modified layer is set, which can better reduce the lattice mismatch problem between the substrate and the epitaxial layer.

[0051] Optionally, along the direction from the first surface to the second surface of the substrate, the values ​​of x, y, and z in the modified layer gradually decrease to zero.

[0052] Optionally, when the diffusion depth of the diffusion element is in the range of 0 nm to 200 nm along the direction from the first surface to the second surface of the substrate, the percentage of x is between 50% and 80%, the percentage of y is between 10% and 25%, and the percentage of z is between 60% and 100%. In this embodiment, the setting of the percentages of x, y, and z can reduce the lattice mismatch between the substrate and the epitaxial layer to below 8%.

[0053] Optionally, when the diffusion depth of the diffusion element is in the range of 200 nm to 400 nm along the direction from the first surface to the second surface of the substrate, the percentage of x is between 30% and 50%, the percentage of y is between 0% and 10%, and the percentage of z is between 30% and 60%.

[0054] Optionally, when the diffusion depth of the diffusion element is in the range of 400 nm to 600 nm along the direction from the first surface to the second surface of the substrate, the percentage of x is between 10% and 30%, the percentage of y is 0%, and the percentage of z is between 10% and 30%.

[0055] Optionally, when the diffusion depth of the diffusion element is in the range of 600 nm to 1000 nm along the direction from the first surface to the second surface of the substrate, the percentage of x is between 0% and 10%, the percentage of y is 0%, and the percentage of z is between 0% and 10%.

[0056] Optionally, the body layer may be made of sapphire.

[0057] This embodiment also provides a method for forming a substrate, including:

[0058] A substrate body is provided, the substrate body having a first surface and a second surface disposed opposite to each other;

[0059] A modified layer is formed within the substrate body to divide the substrate into a modified layer and a body layer; the modified layer extends from the first surface of the substrate body in a direction perpendicular to the substrate body to the second surface, and the body layer extends from the side of the modified layer away from the first surface to the second surface, and the side of the body layer away from the modified layer forms the second surface of the substrate.

[0060] The modified layer contains elements from the bulk layer as well as diffusion elements other than those contained in the bulk layer. The diffusion elements include at least one of Al, Ga, In, and N.

[0061] Optionally, the step of providing a substrate body includes:

[0062] A crystal ingot is provided, and a wafer is obtained by wire cutting the crystal ingot;

[0063] After grinding, annealing, chamfering, copper polishing and polishing are performed on the wafer in sequence, the substrate body is obtained.

[0064] Optionally, the step of forming the modified layer within the substrate body includes:

[0065] A coating layer is coated on the surface of the substrate, and the coating layer contains at least one of Al, Ga, In and N elements;

[0066] The substrate with the coating layer is annealed at a temperature between 1300℃ and 2000℃. In this embodiment, annealing is used to thermally diffuse the elements in the coating layer into the substrate, reducing the lattice mismatch between the substrate and the epitaxial layer. At the same time, the annealing process further reduces the warpage of the substrate at high temperatures, thereby improving the internal quantum efficiency and wavelength uniformity of the epitaxial layer.

[0067] Optionally, the step of annealing the substrate body having the coating layer includes:

[0068] Heating: Increase the temperature to 1300℃~2000℃ at a heating rate of 0.5~200℃ / min;

[0069] Insulation: Insulate at a temperature range of 1300~2000℃ for 1h~40h;

[0070] Cooling: Cool to room temperature at a rate of 0.5–200 °C / min. In this embodiment, the settings of the heating, holding, and cooling parameters for the annealing temperature are more conducive to improving the lattice mismatch problem between the substrate and the epitaxial layer, and can further reduce substrate warpage, improve wavelength uniformity, and internal quantum efficiency.

[0071] Optionally, the material of the substrate body is the same as the material of the body layer.

[0072] This embodiment also provides a light-emitting diode, including:

[0073] The substrate is the substrate described above;

[0074] The epitaxial layer, starting from the first surface of the substrate, sequentially includes a first semiconductor layer, an active layer, and a second semiconductor layer. The light-emitting diode in this embodiment includes the aforementioned substrate, which similarly improves the lattice mismatch problem between the substrate and the epitaxial layer, and further reduces warpage divergence of the substrate at high temperatures, improving wavelength uniformity and internal quantum efficiency.

[0075] Optionally, the material of the first semiconductor layer is GaN.

[0076] Optionally, the light-emitting diode also includes:

[0077] An undoped layer is disposed between the substrate and the first semiconductor layer, which can further reduce the lattice mismatch between the substrate and the epitaxial layer.

[0078] Optionally, the light-emitting diode also includes:

[0079] The first electrode is connected to the first semiconductor layer;

[0080] The second electrode is connected to the second semiconductor layer.

[0081] The following detailed description of this embodiment is based on specific examples.

[0082] Example 1

[0083] This embodiment provides a substrate, as shown in the reference. Figure 1The substrate 100 has a first surface 110 and a second surface 120 disposed opposite to each other. The substrate 100 includes a modified layer 101 and a body layer 102. The modified layer 101 extends from the first surface 110 of the substrate 100 toward the second surface 120 in a direction perpendicular to the substrate 100. The body layer 102 extends from the side of the modified layer 101 away from the first surface 110 toward the second surface 120, and the side of the body layer 102 away from the modified layer 101 forms the second surface 120 of the substrate 100.

[0084] Specifically, refer to Figure 1 and 2 The modified layer 101 is formed by the diffusion of a diffusion element from the first surface 110 of the substrate body 001 into the interior of the substrate body 001. The portion of the substrate body 001 containing the diffusion element forms the modified layer 101, while the portion without the diffusion element forms the body layer 102. It should be noted that the substrate body 001 is formed by wire-cutting a crystal ingot, followed by sequential grinding, annealing, chamfering, copper polishing, and polishing of the resulting wafer. The substrate body 001 can be any substrate used for semiconductor device manufacturing, such as glass, compound semiconductors, metals and alloys, oxides, nitrides, group III-V compounds, group IV elements and compounds, halides, silicates, carbonates, etc. This embodiment uses a sapphire substrate as an example.

[0085] Reference Figure 1 The modified layer 101 contains elements from the bulk layer 102 as well as diffusion elements other than those contained in the bulk layer 102. The diffusion elements include at least one of Al, Ga, In, and N. Any one of Al, Ga, In, and N is diffused into the substrate bulk 001. Elements with different atomic radii can change the lattice constant of the first surface 110 of the substrate 100, thereby improving the lattice mismatch problem between the epitaxial layer 300 subsequently formed on the first surface 110 of the substrate 100 and the substrate 100. Furthermore, when the epitaxial layer 300 is subsequently formed, it is directly formed on the modified layer 101 of the substrate 100 without the need for additional lattice mismatch buffer layers, which is beneficial for improving production efficiency.

[0086] Reference Figure 1 and 2 In this embodiment, the material of the modified layer 101 is (Al). 1-x-y Ga x In y )2(O 1-z N z3, where z ≥ x + y, 0 ≤ x, 0 ≤ y. Specifically, from the first surface 110 of the substrate 100 to the second surface 120, the values ​​of x, y, and z in the modified layer 101 gradually decrease to zero. Furthermore, the thickness of the modified layer 101, that is, the depth from the first surface 110 of the substrate body 001 into the interior of the substrate body 001, is between 100 nm and 1000 nm.

[0087] In one example, refer to Figure 1 At the same time, refer to Figure 4 (The depth from the surface in the figure refers to the distance from the test position to the first surface 110 of the substrate along the direction perpendicular to the substrate 100.) From the first surface 110 to the second surface 120 of the substrate 100, when the diffusion depth of the diffusion element in the modified layer 101 is in the range of 0 nm to 200 nm, the percentage of x is between 50% and 80%, the percentage of y is between 10% and 25%, and the percentage of z is between 60% and 100%. When the diffusion depth of the diffusion element is in the range of 200 nm to 400 nm, the percentage of x is between 30% and 50%, the percentage of y is between 0% and 10%, and the percentage of z is between 30% and 60%. When the diffusion depth of the diffusion element is in the range of 400 nm to 600 nm, the percentage of x is between 10% and 30%, the percentage of y is 0%, and the percentage of z is between 10% and 30%. The diffusion depth of the diffusing element is in the range of 600 nm to 1000 nm, with the percentage of x ranging from 0% to 10%, y from 0%, and z from 0% to 10%. For example, when the diffusion depth of the diffusing element is 0 cm, the percentage content of x in the modified layer 101 is 75%, the percentage content of y is 15%, and the percentage content of z is 90%. When the diffusion depth of the diffusing element is 200 cm, the percentage content of x is 50%, the percentage content of y is 10%, and the percentage content of z is 60%.

[0088] Reference Figure 1 At the same time, refer to Figure 5 Within the modified layer 101, as the diffusion depth increases from the first surface 110 to the second surface 120 of the substrate 100, the proportion of lattice mismatch also gradually increases. When the diffusion depth of the diffusing element is in the range of 0 nm to 200 nm, the lattice mismatch proportion is less than 8%, and when the diffusion depth is 0 nm, that is, the lattice mismatch proportion on the first surface 110 of the substrate 100 is as low as 2%.

[0089] Reference Figure 2The body layer 102 extends from the modified layer 101 away from the first surface 110 of the substrate 100 to the second surface 120, until the side of the body layer 102 away from the modified layer 101 forms the second surface 120 of the substrate 100. This body layer 102 does not contain any diffusion elements, and the material of the body layer 102 is the same as the material of the substrate 001. In this embodiment, the material of the body layer 102 is sapphire.

[0090] The substrate in this embodiment includes a modified layer containing diffusion elements other than the substrate bulk material. These diffusion elements can alter the lattice parameters of the substrate surface while maintaining the substrate's crystal structure, improving the lattice matching between the substrate and the epitaxial layer, reducing the dislocation density within the epitaxial layer, and thus improving the internal quantum efficiency of the light-emitting diode. Furthermore, the doping atomic content and lattice parameters of the modified layer gradually change with increasing diffusion depth. These changes significantly improve the lattice matching with the epitaxial layer, thereby optimizing the internal quantum efficiency of the epitaxial layer.

[0091] Example 2

[0092] This embodiment provides a method for forming a substrate, which includes the following steps:

[0093] S1: A substrate body is provided, the substrate body having a first surface and a second surface disposed opposite to each other;

[0094] Specifically, refer to Figure 2 The method for forming a substrate body 001 includes: providing a crystal rod, which is obtained by crystal growth. Specifically, taking a sapphire substrate as an example, the crystal growth process is usually as follows: first, the raw material aluminum oxide is placed in a crucible, and the crucible and the aluminum oxide therein are heated to a temperature above 2000℃, so that the aluminum oxide melts into a molten state. Then, through steps such as crystal pulling, shoulder formation, and constant diameter growth, a sapphire crystal is obtained. The obtained crystal is then subjected to rod-shaping treatment to obtain a sapphire crystal rod.

[0095] The obtained crystal rod is cut using a wire cutting process to obtain a wafer of a predetermined thickness. The cut wafer is then subjected to grinding, annealing, chamfering, copper polishing, and polishing processes to obtain the substrate body 001 in this embodiment.

[0096] It should be noted that the substrate body 001 can be any substrate used for semiconductor device manufacturing, such as glass, compound semiconductor, metal and alloy, oxide, nitride, group III and V compound, group IV element and compound, halide, silicate, carbonate, etc. This embodiment uses a sapphire substrate as an example for illustration.

[0097] S2: A modified layer is formed within the substrate body to divide the substrate into a modified layer and a body layer. The modified layer extends from the first surface of the substrate body to the second surface in a direction perpendicular to the substrate body. The body layer extends from the side of the modified layer away from the first surface to the second surface. The side of the body layer away from the modified layer forms the second surface of the substrate. The modified layer contains elements from the body layer and diffusion elements other than those contained in the body layer. The diffusion elements include at least one of Al, Ga, In, and N.

[0098] Specifically, refer to Figure 3 A coating layer 002 is coated on the first surface 110 of the substrate body 001. The coating layer 002 contains at least one of Al, Ga, In, and N. The coating layer 002 is formed by: providing at least two of the following raw materials: indium, gallium, or aluminum oxide, indium, gallium, or aluminum nitride, or indium, gallium, or aluminum nitrate, and mixing them in a solvent to form a solution or colloid. The solvent can be at least one of water, alcohol, or ketone. The formed solution or colloid is coated on the surface of the substrate body 001, and the substrate body 001 coated with the solution or colloid is baked at a temperature of 150°C to 300°C for 0 to 2 hours to cure the coating layer and form the coating layer 002.

[0099] The substrate body 001 with the coating layer 002 is placed in a heating furnace for annealing. The annealing temperature is between 1300℃ and 2000℃, and the annealing time is between 1h and 40h. Specifically, the heating process involves: heating the furnace to 1300℃ to 2000℃ at a heating rate of 0.5℃ to 200℃ / min; holding the temperature at 1300℃ to 2000℃ for 1h to 40h; and cooling the furnace to room temperature at a cooling rate of 0.5℃ to 200℃ / min.

[0100] Reference Figure 1 and 2 The annealed substrate body 001 forms the substrate 100 in this embodiment 1. Al, Ga, In, and N elements are diffused from the first surface 110 to the second surface 120 of the substrate 100. The portion of the substrate body 001 with diffused elements forms a modified layer 101, and the portion without diffused elements forms a body layer 102. The specific structure of the substrate 100 is the same as described in embodiment 1, and will not be repeated here.

[0101] In this embodiment, the substrate is formed by depositing a coating layer on the surface of the substrate body. An annealing process is then performed to allow at least one element from the coating layer (Al, Ga, In, N) to diffuse from the first surface of the substrate body into the substrate body via thermal diffusion. This modifies the first surface of the substrate body, making the lattice constant of the modified layer closer to that of the epitaxial layer. This reduces the lattice mismatch between the substrate and the epitaxial layer, as well as the dislocation density of the epitaxial layer, thereby improving the internal quantum efficiency of the epitaxial layer. Simultaneously, the secondary annealing process significantly reduces residual stress during substrate machining, minimizing warpage at high temperatures and optimizing substrate performance. Because the substrate is less prone to warpage at high temperatures, it can maintain sufficient thermal contact with the graphite disk in subsequent processes, improving the temperature difference within the substrate surface. This enhances the uniformity of the bandgap width of the quantum wells in the epitaxial layer grown on the substrate, ultimately optimizing the uniformity of the epitaxial wavelength.

[0102] Example 3

[0103] This embodiment provides a light-emitting diode, as shown in the reference. Figure 6 The light-emitting diode includes a substrate 100 and an epitaxial layer 300. The substrate 100 is the same as the substrate 100 in Embodiment 1 or 2, and will not be described again here. The epitaxial layer 300 includes a first semiconductor layer 301, an active layer 302 and a second semiconductor layer 303 stacked sequentially on the first surface of the substrate 100.

[0104] In this embodiment, the first semiconductor layer 301 can be an N-type semiconductor layer, and the second semiconductor layer 303 can be a P-type semiconductor layer. Alternatively, the first semiconductor layer 301 can be a P-type semiconductor layer, and the second semiconductor layer 303 can be an N-type semiconductor layer. The first semiconductor layer 301 provides electrons for recombination emission, and the second semiconductor layer 303 provides holes for recombination emission. The active layer 302 is a single quantum well or multiple quantum wells, used for recombination emission of electrons and holes. In this embodiment, the first semiconductor layer 301 is made of GaN material, which exhibits a significant lattice mismatch with the sapphire substrate 100. This embodiment modifies the first surface 110 of the substrate 100, reducing the lattice mismatch between the modified substrate 100 and the GaN material from 16% to less than 5%. Consequently, the epitaxial layer 300 grown on the modified layer 101 surface of the substrate 100 has fewer dislocation defects, which is beneficial to the growth quality and efficiency of the epitaxial layer 300.

[0105] To further reduce the lattice mismatch between the substrate 100 and the epitaxial layer 300, in this embodiment, an undoped layer 200 is formed between the first semiconductor layer 301 and the substrate 100. The undoped layer 200 can be a single layer or multiple layers. For example, when the undoped layer 200 is a single layer, its material can be a GaN layer. When the undoped layer 200 is a double layer, its material can be a stacked combination of AlN and GaN layers.

[0106] The light-emitting diode (LED) also includes a first electrode 401 and a second electrode 402. The first electrode 401 is connected to the first semiconductor layer 301, and the second electrode 402 is connected to the second semiconductor layer 303. Furthermore, the LED may also include structural layers that optimize LED performance, such as a transparent conductive layer, a current-blocking layer, and a reflective layer; these will not be detailed here. Testing the LED in this embodiment shows that the internal quantum efficiency can be improved by 2%, and the wavelength uniformity can be improved by 5%.

[0107] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A substrate, characterized in that, The substrate has a first surface and a second surface disposed opposite to each other, the substrate comprising: A modified layer extends from the first surface of the substrate toward the second surface in a direction perpendicular to the substrate; A body layer extends from the side of the modified layer away from the first surface toward the second surface, and the side of the body layer away from the modified layer forms the second surface of the substrate; The modified layer contains elements from the body layer and diffusion elements other than those contained in the body layer. The diffusion elements include at least one of Al, Ga, In, and N. The material of the modified layer is (Al). 1-x-y Ga x In y )2(O 1-z N z 3, where z ≧ x+y, 0≤x, 0≤y; Along the direction from the first surface to the second surface of the substrate, the values ​​of x, y, and z in the modified layer gradually decrease to zero. When the diffusion depth of the diffusion element is in the range of 0 nm to 200 nm, the percentage of x is between 50% and 80%, the percentage of y is between 10% and 25%, and the percentage of z is between 60% and 100%. When the diffusion depth of the diffusion element is in the range of 200 nm to 400 nm, the percentage of x is between 30% and 50%, the percentage of y is between 0% and 10%, and the percentage of z is between 30% and 60%.

2. The substrate according to claim 1, characterized in that, The thickness of the modified layer is between 100 nm and 1000 nm.

3. The substrate according to claim 1, characterized in that, Along the direction from the first surface to the second surface of the substrate, when the diffusion depth of the diffusion element is in the range of 400 nm to 600 nm, the percentage of x is between 10% and 30%, the percentage of y is 0%, and the percentage of z is between 10% and 30%.

4. The substrate according to claim 1, characterized in that, Along the direction from the first surface to the second surface of the substrate, when the diffusion depth of the diffusion element is in the range of 600 nm to 1000 nm, the percentage of x is between 0% and 10%, the percentage of y is 0%, and the percentage of z is between 0% and 10%.

5. The substrate according to claim 1, characterized in that, The material of the body layer is sapphire.

6. A method for forming a substrate, characterized in that, The substrate formed is the substrate according to any one of claims 1 to 5, and the method for forming the substrate includes: A substrate body is provided, the substrate body having a first surface and a second surface disposed opposite to each other; A modification layer is formed within the substrate body to divide the substrate into a modification layer and a body layer; the modification layer extends from a first surface of the substrate body in a direction perpendicular to the substrate body toward a second surface, and the body layer extends from the side of the modification layer away from the first surface toward the second surface, with the side of the body layer away from the modification layer forming the second surface of the substrate. The modified layer contains elements from the body layer as well as diffusion elements other than those contained in the body layer, wherein the diffusion elements include at least one of Al, Ga, In, and N.

7. The method for forming a substrate according to claim 6, characterized in that, The step of providing a substrate body includes: A crystal rod is provided, and a wafer is obtained by wire cutting the crystal rod; The wafer is subjected to grinding, annealing, chamfering, copper polishing and polishing in sequence to obtain the substrate body.

8. The method for forming a substrate according to claim 6, characterized in that, The step of forming a modified layer within the substrate body includes: A coating layer is coated on the surface of the substrate body, and the coating layer contains at least one of the elements Al, Ga, In, and N; The substrate body having the coating layer is subjected to annealing treatment at a temperature between 1300℃ and 2000℃.

9. The method for forming a substrate according to claim 8, characterized in that, The step of annealing the substrate body having the coating layer includes: Heating: Increase the temperature to 1300℃~2000℃ at a heating rate of 0.5~200℃ / min; Insulation: Insulate at a temperature range of 1300~2000℃ for 1 h~40 h; Cooling: Cool to room temperature at a rate of 0.5~200℃ / min.

10. The method for forming a substrate according to claim 6, characterized in that, The material of the substrate body is the same as the material of the body layer.

11. A light-emitting diode, characterized in that, include: The substrate is the substrate according to any one of claims 1 to 5; The epitaxial layer comprises, sequentially from the first surface of the substrate, a first semiconductor layer, an active layer, and a second semiconductor layer.

12. The light-emitting diode according to claim 11, characterized in that, The material of the first semiconductor layer is GaN.

13. The light-emitting diode according to claim 11, characterized in that, The light-emitting diode also includes: An undoped layer is disposed between the substrate and the first semiconductor layer.

14. The light-emitting diode according to claim 11, characterized in that, The light-emitting diode also includes: The first electrode is connected to the first semiconductor layer; The second electrode is connected to the second semiconductor layer.

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