CN107887480B - Preparation method of light-emitting diode epitaxial wafer and light-emitting diode epitaxial wafer - Google Patents

Abstract

The present invention discloses a method for preparing a light-emitting diode epitaxial wafer and a light-emitting diode epitaxial wafer, belonging to the field of semiconductor technology. The method comprises: growing a first undoped gallium nitride layer on a buffer layer stacked on a substrate; forming a colloidal crystal film on the first undoped gallium nitride layer, the colloidal crystal film comprising a plurality of organic particles arranged in an array; depositing an oxide film on and between the plurality of organic particles; heating the plurality of organic particles, the plurality of organic particles decomposing into gas during the temperature increase process and being discharged from between the oxide film and the first undoped gallium nitride layer, and forming a plurality of cavities arranged in an array between the first undoped gallium nitride layer and the oxide film; growing a second undoped gallium nitride layer on the oxide film; and sequentially growing an N-type gallium nitride layer, a multi-quantum well layer, an electron blocking layer and a P-type gallium nitride layer on the second undoped gallium nitride layer to form an epitaxial wafer. The present invention improves the consistency of the epitaxial wafer.

Description

Method for preparing light-emitting diode epitaxial wafer and light-emitting diode epitaxial wafer

technical field

The invention relates to the technical field of semiconductors, in particular to a method for preparing a light-emitting diode epitaxial wafer and the light-emitting diode epitaxial wafer.

Background technique

Light Emitting Diode (English: Light Emitting Diode, referred to as: LED) is a semiconductor light emitting device made by using the principle of semiconductor PN junction electroluminescence. The epitaxial wafer is the primary product in the process of manufacturing light-emitting diodes.

The existing epitaxial wafer includes a sapphire substrate and a buffer layer, an undoped gallium nitride layer, an n-type gallium nitride layer, a multi-quantum well layer, an electron blocking layer and a p-type gallium nitride layer stacked on the sapphire substrate in sequence. Floor. The electrons provided by the N-type gallium nitride layer and the holes provided by the P-type gallium nitride layer can be injected into the multi-quantum well layer to recombine and emit light under the drive of current.

In the process of realizing the present invention, the inventor finds that there are at least the following problems in the prior art:

There is a large lattice mismatch (16.9%) between sapphire and gallium nitride. Deposit gallium nitride material on the sapphire substrate to form an epitaxial wafer. There will be a large gap between the sapphire and gallium nitride at the bottom of the epitaxial wafer. Lattice mismatch, the dislocation and stress generated by the lattice mismatch will extend in GaN as GaN continues to be deposited, affecting the growth quality of the multi-quantum well layer in which electrons and holes recombine and emit light. Since small differences in growth conditions will cause different dislocations and stresses generated by lattice mismatch at the bottom of the epitaxial wafers, the growth quality of the multi-quantum well layer in each epitaxial wafer is usually different, and the photoelectric performance of the epitaxial wafer is mainly determined by the multi-quantum well layer. The layer is determined, so the photoelectric properties of each epitaxial wafer will also be different, resulting in poor consistency of the epitaxial wafer.

SUMMARY OF THE INVENTION

In order to solve the problem of poor consistency of the light-emitting diode epitaxial wafer in the prior art, the embodiment of the present invention provides a preparation method of the light-emitting diode epitaxial wafer and the light-emitting diode epitaxial wafer. Described technical scheme is as follows:

On the one hand, an embodiment of the present invention provides a method for preparing a light-emitting diode epitaxial wafer, the preparation method comprising:

growing a first undoped gallium nitride layer on the buffer layer stacked on the substrate;

forming a colloidal crystal thin film on the first undoped gallium nitride layer, the colloidal crystal thin film comprising a plurality of organic particles arranged in an array on the first undoped gallium nitride layer;

depositing an oxide film on and between the plurality of organic particles;

heating the plurality of organic particles, the plurality of organic particles are decomposed into gas and discharged from between the oxide film and the first undoped gallium nitride layer during the process of temperature rise, the A plurality of cavities arranged in an array are formed between the first undoped gallium nitride layer and the oxide film;

growing a second undoped gallium nitride layer on the oxide film;

An N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer are sequentially grown on the second undoped GaN layer to form an epitaxial wafer.

Optionally, the preparation method also includes:

applying a laser to the oxide film, using the plurality of cavities to separate the first undoped gallium nitride layer from the second undoped gallium nitride layer;

Etching the first undoped gallium nitride layer until the surface of the first undoped gallium nitride layer is flat to obtain a substrate stacked with a buffer layer.

Optionally, the growing the first undoped gallium nitride layer on the buffer layer stacked on the substrate includes:

providing a substrate stacked with a buffer layer;

A first undoped gallium nitride layer is grown on the buffer layer.

Optionally, the growing the first undoped gallium nitride layer on the buffer layer stacked on the substrate includes:

growing a buffer layer on the substrate;

A first undoped gallium nitride layer is grown on the buffer layer.

Optionally, forming a colloidal crystal film on the first undoped gallium nitride layer, the colloidal crystal film comprising a plurality of organic particles arranged in an array on the first undoped gallium nitride layer ,include:

Dispersing the precursor in a solvent and reacting to generate the organic particles;

The solvent is evaporated, and the organic particles are arranged in an array under the capillary action induced by the evaporation of the solvent to form the colloidal crystal film.

Optionally, the diameter of the organic particles is 0.5 μm˜1.8 μm.

Preferably, the material of the organic particles is polystyrene.

Optionally, the oxide film is made of aluminum oxide or zinc oxide.

Optionally, the thickness of the oxide film is 0.5nm-50nm.

On the other hand, an embodiment of the present invention provides a light-emitting diode epitaxial wafer, the light-emitting diode epitaxial wafer includes a buffer layer, an N-type gallium nitride layer, a multi-quantum well layer, and a substrate sequentially stacked on the substrate. An electron blocking layer and a P-type gallium nitride layer, the light-emitting diode epitaxial wafer also includes a first undoped gallium nitride layer and a colloidal crystal film stacked between the buffer layer and the N-type gallium nitride layer , an oxide thin film and a second undoped gallium nitride layer, the first undoped gallium nitride layer is arranged on the buffer layer, and the colloidal crystal thin film includes an array arranged on the first undoped gallium nitride layer a plurality of organic particles on the gallium nitride layer, the oxide thin film is arranged on the plurality of organic particles and between the plurality of organic particles, and the second undoped gallium nitride layer is arranged on the oxide film.

The beneficial effects brought by the technical solution provided by the embodiments of the present invention are:

By first forming a colloidal crystal film including a plurality of organic particles arranged in an array in the undoped gallium nitride layer, and depositing an oxide film on the colloidal crystal film, and then heating the multiple organic particles, the organic particles are heated at a temperature During the rising process, it is decomposed into gas and discharged, thereby forming multiple cavities arranged in an array at the oxide film in the undoped gallium nitride layer, so that after the formation of the epitaxial wafer, the laser acts on the oxide film, The undoped gallium nitride layer can be divided into two parts by using the cavity, and after the part where the substrate with the buffer layer is stacked is modified, other epitaxial wafers can be grown. Since the bottom layer of each epitaxial wafer (the substrate with the buffer layer stacked) is the same, the influence of the lattice mismatch between sapphire and gallium nitride in each epitaxial wafer is also the same, thereby avoiding the crystal lattice The difference in mismatch eventually leads to different photoelectric properties of the epitaxial wafer, which improves the consistency of the epitaxial wafer. In addition, the present invention can also reduce the subsequent process of thinning and grinding the substrate, which is simpler to implement and takes less time. At the same time, it can also avoid the problem of stress release in the process of substrate thinning and improve the efficiency of epitaxy. Improve the quality of chip processing, reduce production costs and improve output efficiency.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

Fig. 1 is a flowchart of a method for preparing a light-emitting diode epitaxial wafer provided by Embodiment 1 of the present invention;

Fig. 2a-Fig. 2g are structural schematic diagrams of light-emitting diode epitaxial wafers during the execution of the preparation method provided by Embodiment 1 of the present invention;

Fig. 3 is a flowchart of a method for preparing a light-emitting diode epitaxial wafer provided by Embodiment 2 of the present invention;

FIG. 4 is a schematic structural view of a light-emitting diode epitaxial wafer provided by Embodiment 3 of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Example 1

An embodiment of the present invention provides a method for preparing a light-emitting diode epitaxial wafer, as shown in FIG. 1 , the preparation method includes:

Step 101: growing a buffer layer on a substrate.

Specifically, the substrate can be sapphire with [0001] crystal orientation.

Optionally, before step 101, the preparation method may also include:

The temperature is controlled at 1000° C. to 1200° C., the substrate is annealed in a hydrogen atmosphere for 8 minutes, and nitriding treatment is performed to clean the substrate.

Specifically, this step 101 may include:

The temperature is controlled at 400° C. to 600° C., the pressure is 400 Torr to 600 Torr, and a gallium nitride layer with a thickness of 15 nm to 35 nm is grown on the substrate to form a buffer layer.

Optionally, after step 101, the preparation method may further include:

The temperature is controlled to be 1000° C. to 1200° C., the pressure is 400 Torr to 600 Torr, and the duration is 5 minutes to 10 minutes, and an in-situ annealing treatment is performed on the buffer layer.

Step 102: growing a first undoped GaN layer on the buffer layer.

Specifically, this step 102 may include:

The temperature is controlled at 1000° C. to 1100° C., the pressure is 100 torr to 500 torr, and a first undoped gallium nitride layer with a thickness of 0.1 μm to 1 μm is grown on the buffer layer.

It should be noted that steps 101 to 102 are an implementation manner of growing a first undoped gallium nitride layer on a buffer layer stacked on a substrate, which is mainly applied when forming an epitaxial wafer for the first time. Fig. 2a is a schematic structural view of an epitaxial wafer after growing a first undoped gallium nitride layer on a buffer layer stacked on a substrate. Wherein, 10 is a substrate, 20 is a buffer layer, and 31 is a first undoped gallium nitride layer. As shown in FIG. 2 a , the buffer layer 20 and the first undoped gallium nitride layer 31 are sequentially stacked on the substrate 10 .

Step 103: forming a colloidal crystal film on the first undoped GaN layer, the colloidal crystal film including a plurality of organic particles arranged in an array on the first undoped GaN layer.

FIG. 2b is a schematic diagram of the structure of the epitaxial wafer after step 103 is performed. Among them, 41 is the organic particle in the colloidal crystal film. As shown in FIG. 2 b , a plurality of organic particles 41 are uniformly distributed on the first undoped GaN layer 31 .

It should be noted that the growth of the buffer layer and the first undoped gallium nitride layer is carried out by placing the substrate in a Metal-organic Chemical Vapor Deposition (English: Metal-organic Chemical Vapor Deposition, referred to as: MOCVD) reaction chamber. , when forming the colloidal crystal thin film, the substrate needs to be cooled to room temperature first, and then the substrate is taken out from the MOCVD reaction chamber, and then the colloidal crystal thin film is formed on the first undoped gallium nitride layer.

Optionally, this step 103 may include:

Disperse the precursor in a solvent and react to generate organic particles;

The solvent is evaporated, and the organic particles are arranged in an array under the capillary action induced by solvent evaporation to form a colloidal crystal film.

Through the above steps, the colloidal crystal thin film can be formed. In practical applications, other implementation methods may also be used, such as applying an electric field that generates electrostatic force to form a colloidal crystal film, and the present invention is not limited thereto.

Optionally, the diameter of the organic particles may be 0.5 μm˜1.8 μm. If the diameter of the organic particles is less than 0.5 μm, it may not be possible to effectively separate the first undoped gallium nitride layer from the second undoped gallium nitride layer; if the diameter of the organic particles is greater than 1.8 μm, it may cause the first The undoped GaN layer is separated from the oxide film after the organic particles are decomposed into gas and discharged, so that the second undoped GaN layer cannot be deposited on the oxide film.

Preferably, the material of the organic particles can be polystyrene. On the one hand, the diameter of the organic particles formed by polystyrene can meet the requirements of 0.5 μm to 1.8 μm; on the other hand, polystyrene is a common material for colloidal crystal films, and the acquisition cost is low.

Step 104: Deposit an oxide film on and between the organic particles.

FIG. 2c is a schematic diagram of the structure of the epitaxial wafer after step 104 is performed. Among them, 50 is an oxide film. As shown in FIG. 2 c , an oxide film 50 is deposited on and between the plurality of organic particles 41 .

Optionally, this step 104 may include:

An oxide thin film is deposited on and between a plurality of organic particles by atomic layer deposition technology.

Optionally, aluminum oxide or zinc oxide can be used as a material for the oxide film, so that it can be prepared at room temperature and avoid damage to organic particles.

Optionally, the thickness of the oxide film may be 0.5nm˜50nm, so as to ensure the separation of the first undoped GaN layer and the second undoped GaN layer.

Step 105: heating a plurality of organic particles, the plurality of organic particles are decomposed into gases during the temperature rise process and discharged from between the oxide film and the first undoped gallium nitride layer, the first undoped gallium nitride layer Multiple cavities arranged in an array are formed between the gallium layer and the oxide film.

FIG. 2d is a schematic diagram of the structure of the epitaxial wafer after step 105 is performed. Wherein, 42 is a cavity. As shown in FIG. 2 d , the organic particles 41 have been decomposed into gas and discharged, leaving cavities 42 , and each cavity 42 is arranged in an array on the first undoped GaN layer 31 .

It should be noted that after the cavity is formed, the surface of each layer such as the substrate can be cleaned first, and then the substrate can be placed in the MOCVD reaction chamber for subsequent growth.

Step 106: growing a second undoped GaN layer on the oxide film.

FIG. 2e is a schematic diagram of the structure of the epitaxial wafer after step 106 is performed. Wherein, 32 is the second undoped gallium nitride layer. As shown in FIG. 2 e , a second undoped gallium nitride layer 32 is deposited on the oxide film 50 .

Optionally, the growth conditions of the first undoped GaN layer can be the same as the growth conditions of the second undoped GaN layer, and the growth conditions include growth temperature and growth pressure.

Optionally, the thickness of the first undoped GaN layer may be the same as that of the second undoped GaN layer.

Specifically, this step 106 may include:

The temperature is controlled at 1000° C. to 1100° C., the pressure is 100 torr to 500 torr, and a second undoped gallium nitride layer with a thickness of 0.1 μm to 1 μm is grown on the oxide film.

Step 107: growing an N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer sequentially on the second undoped GaN layer to form an epitaxial wafer.

FIG. 2f is a schematic diagram of the structure of the epitaxial wafer after step 107 is performed. Wherein, 60 is an N-type gallium nitride layer, 70 is a multi-quantum well layer, 80 is an electron blocking layer, and 90 is a P-type gallium nitride layer. As shown in FIG. 2 f , the N-type GaN layer 60 , the multi-quantum well layer 70 , the electron blocking layer 80 and the P-type GaN layer 90 are sequentially stacked on the second undoped GaN layer 32 .

Specifically, this step 107 may include:

Controlling the temperature at 1000°C to 1200°C and the pressure at 100torr to 500torr, growing N with a thickness of 1 μm to 5 μm and a doping concentration of 10 ¹⁸ cm ^-3 to 10 ¹⁹ cm ^-3 on the second undoped gallium nitride layer type gallium nitride layer;

The control pressure is 100torr~500torr, and the indium gallium nitride layer with a thickness of 3nm and the gallium nitride layer with a thickness of 9nm~20nm are alternately grown on the N-type gallium nitride layer, and the growth temperature of the indium gallium nitride layer is 720℃~829℃ , the growth temperature of the gallium nitride layer is 850°C to 959°C, the number of the gallium nitride layer is the same as the number of the indium gallium nitride layer, and the number of the indium gallium nitride layer is 5 to 15, forming a multi-quantum well layer;

Control the temperature at 850°C to 1080°C and the pressure at 200torr to 500torr, and grow a P-type Al _y Ga _1-y N layer (0.1<y<0.5) with a thickness of 50nm to 150nm on the multi-quantum well layer to form an electron blocking layer ;

Control the temperature at 750°C to 1080°C and the pressure at 200torr to 500torr, and grow a P-type gallium nitride layer with a thickness of 100nm to 200nm on the electron blocking layer;

The temperature is controlled at 850° C. to 1050° C., the pressure is 100 torr to 300 torr, and the P-type gallium nitride layer with a thickness of 5 nm to 300 nm is continuously grown.

Optionally, after step 107, the preparation method may also include:

The temperature is controlled at 650° C. to 850° C., the duration is 5 minutes to 15 minutes, and the annealing treatment is performed in a nitrogen atmosphere.

It should be noted that, in this embodiment, controlling temperature and pressure both refer to controlling the temperature and pressure in the reaction chamber for growing epitaxial wafers. When it is realized, trimethylgallium or trimethylethyl is used as the gallium source, high-purity nitrogen is used as the nitrogen source, trimethylindium is used as the indium source, trimethylaluminum is used as the aluminum source, the N-type dopant is silane, and the P-type dopant is silane. Miscellaneous agent selects dichloromagnesium for use.

Step 108 : applying a laser to the oxide film, using a plurality of cavities to separate the first undoped GaN layer and the second undoped GaN layer.

FIG. 2g is a schematic diagram of the structure of the epitaxial wafer after step 108 is performed. As shown in Figure 2g, after the laser action, the oxide film 50 is split, the first undoped gallium nitride layer 31 and the second undoped gallium nitride layer 32 are separated, and the first undoped gallium nitride layer 31 and the second undoped GaN layer 32 have part of the oxide film 50 remaining.

Step 109: Etching the first undoped GaN layer until the surface of the first undoped GaN layer is flat, to obtain a substrate stacked with buffer layers.

In practical applications, since the separation position is usually not exactly at the interface, it is necessary to modify the surface of the first undoped gallium nitride layer to make it flat. After modification, part of the first undoped GaN layer may remain, or all of the first undoped GaN layer may be etched away.

It should be noted that steps 108 to 109 are optional steps. After the epitaxial wafer is formed, since there are multiple cavities between the oxide film and the first undoped gallium nitride layer, the first undoped nitrogen The gallium nitride layer and the second undoped gallium nitride layer are separated, that is, the epitaxial wafer is divided into two parts: one part includes the first undoped gallium nitride layer, buffer layer and substrate, and the other part includes the second undoped gallium nitride layer A heterogallium nitride layer, an N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer.

Among them, the part where the second undoped gallium nitride layer is located includes the basic structure (N-type gallium nitride layer, multi-quantum well layer and P-type gallium nitride layer) required for the epitaxial wafer to emit light, which can be made by subsequent processing. Light-emitting diode; the part where the first undoped gallium nitride layer is located is the underlying structure of epitaxial wafer growth (including the substrate and buffer layer), and the lattice mismatch between sapphire and gallium nitride has already occurred. If in this stack If other epitaxial wafers are grown on a substrate with a buffer layer, then the dislocations and stresses generated by lattice mismatch in all epitaxial wafers are the same, and the growth quality of multiple quantum well layers in all epitaxial wafers will not be affected by the growth conditions. The small differences of the epitaxial wafers are different, so as to avoid the different photoelectric properties of each epitaxial wafer and improve the consistency of the epitaxial wafers.

In the embodiment of the present invention, a colloidal crystal film including a plurality of organic particles arranged in an array is first formed in the undoped gallium nitride layer, and an oxide film is deposited on the colloidal crystal film, and then the plurality of organic particles are heated, so that The organic particles are decomposed into gases and discharged during the temperature rise, thereby forming multiple cavities arranged in an array at the oxide film in the undoped gallium nitride layer, so that after the formation of the epitaxial wafer, the laser acts on the oxide film. In the object thin film, the undoped gallium nitride layer can be divided into two parts by using the cavity, and after the part where the substrate with the buffer layer is stacked is modified, the growth of other epitaxial wafers can be carried out. Since the bottom layer of each epitaxial wafer (the substrate with the buffer layer stacked) is the same, the influence of the lattice mismatch between sapphire and gallium nitride in each epitaxial wafer is also the same, thereby avoiding the crystal lattice The difference in mismatch eventually leads to different photoelectric properties of the epitaxial wafer, which improves the consistency of the epitaxial wafer.

In addition, the present invention can also reduce the subsequent process of thinning and grinding the substrate, which is simpler to implement and takes less time. At the same time, it can also avoid the problem of stress release in the process of substrate thinning and improve the efficiency of epitaxy. Improve the quality of chip processing, reduce production costs and improve output efficiency.

Embodiment 2

An embodiment of the present invention provides a method for preparing a light-emitting diode epitaxial wafer, as shown in FIG. 3 , the preparation method includes:

Step 201: providing a substrate laminated with a buffer layer.

Specifically, in step 201, the substrate obtained in step 108 and step 109 in the first embodiment with a buffer layer laminated thereon can be used.

Step 202: growing a first undoped GaN layer on the buffer layer.

Specifically, if there is no first undoped gallium nitride layer on the buffer layer stacked on the substrate in step 201, then this step 202 can be the same as step 102 in Embodiment 1, and will not be described in detail here. If the first undoped gallium nitride layer is also laminated on the buffer layer stacked on the substrate in step 201, the thickness of the grown first undoped gallium nitride layer can be correspondingly reduced, so that the grown in step 202 The sum of the thickness of the first undoped GaN layer and the thickness of the first undoped GaN layer stacked on the buffer layer is equal to the thickness of the first undoped GaN layer grown in step 102 .

It should be noted that steps 201 to 202 are different from steps 101 to 102 to realize the growth of the first undoped gallium nitride layer on the buffer layer stacked on the substrate, which can be applied in During the formation of all epitaxial wafers except the first epitaxial wafers formed.

Step 203: forming a colloidal crystal thin film on the first undoped GaN layer, the colloidal crystal thin film including a plurality of organic particles arrayed on the first undoped GaN layer.

Specifically, this step 203 may be the same as step 103 in the first embodiment, and will not be described in detail here.

Step 204: Deposit an oxide film on and between the organic particles.

Specifically, this step 204 may be the same as step 104 in the first embodiment, and will not be described in detail here.

Step 205: heating a plurality of organic particles, the plurality of organic particles are decomposed into gases during the temperature rise process and discharged from between the oxide film and the first undoped gallium nitride layer, the first undoped gallium nitride layer Multiple cavities arranged in an array are formed between the gallium layer and the oxide film.

Specifically, this step 205 may be the same as step 105 in the first embodiment, and will not be described in detail here.

Step 206: growing a second undoped GaN layer on the oxide film.

Specifically, the step 206 may be the same as the step 106 in the first embodiment, and will not be described in detail here.

Step 207: growing an N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer sequentially on the second undoped GaN layer to form an epitaxial wafer.

Specifically, this step 207 may be the same as step 107 in the first embodiment, and will not be described in detail here.

Step 208 : applying a laser to the oxide film, and using a plurality of cavities to separate the first undoped GaN layer and the second undoped GaN layer.

Specifically, the step 208 may be the same as the step 108 in the first embodiment, and will not be described in detail here.

Step 209: Etching the first undoped GaN layer until the surface of the first undoped GaN layer is flat to obtain a substrate stacked with buffer layers.

Specifically, this step 209 may be the same as step 109 in Embodiment 1, and will not be described in detail here.

It can be understood that after step 209 is performed, steps 201 to 207 can be performed again to form an epitaxial wafer, and then steps 208 and 209 can be performed to obtain a substrate laminated with a buffer layer, and steps 201 to 207 can be performed again to form an epitaxial wafer , and then perform step 208 and step 209 to obtain a substrate laminated with a buffer layer, ..., and so on, until all epitaxial wafers are manufactured.

Embodiment 3

The embodiment of the present invention provides a light-emitting diode epitaxial wafer, which can be prepared by the preparation method provided in the above-mentioned embodiment 1 or embodiment 2. Specifically, referring to FIG. 4, the light-emitting diode epitaxial wafer includes a buffer layer, a first undoped gallium nitride layer, a colloidal crystal film, an oxide film, a second undoped gallium nitride layer, and a second undoped gallium nitride layer stacked on the substrate in sequence. Gallium layer, N-type GaN layer, multiple quantum well layer, electron blocking layer and P-type GaN layer.

In this embodiment, the colloidal crystal thin film includes a plurality of organic particles arrayed on the first undoped gallium nitride layer, and the oxide thin film is disposed on and between the plurality of organic particles.

Optionally, the diameter of the organic particles may be 0.5 μm˜1.8 μm. If the diameter of the organic particles is less than 0.5 μm, it may not be possible to effectively separate the first undoped gallium nitride layer from the second undoped gallium nitride layer; if the diameter of the organic particles is greater than 1.8 μm, it may cause the first The undoped GaN layer is separated from the oxide film after the organic particles are decomposed into gas and discharged, so that the second undoped GaN layer cannot be deposited on the oxide film.

Preferably, the material of the organic particles can be polystyrene. On the one hand, the diameter of the organic particles formed by polystyrene can meet the requirements of 0.5 μm to 1.8 μm; on the other hand, polystyrene is a common material for colloidal crystal films, and the acquisition cost is low.

Optionally, aluminum oxide or zinc oxide may be used as a material for the oxide film.

Optionally, the thickness of the oxide film may be 0.5nm˜50nm, so as to ensure the separation of the first undoped GaN layer and the second undoped GaN layer.

Specifically, the substrate is a sapphire substrate. The buffer layer can be a gallium nitride layer or an aluminum nitride layer. The quantum well can be an indium gallium nitride layer, and the quantum barrier can be a gallium nitride layer or an aluminum gallium nitride layer. The electron blocking layer may be a P-type doped _{AlyGa1 -yN} layer, 0.1<y<0.5.

Optionally, the thickness of the buffer layer may be 15nm-35nm.

Optionally, the thickness of the undoped gallium nitride layer may be 1 μm˜5 μm.

Optionally, the thickness of the N-type gallium nitride layer may be 1 μm˜5 μm.

Optionally, the doping concentration of the N-type dopant in the N-type GaN layer may be 10 ¹⁸ cm ^-3 -10 ¹⁹ cm ^-3 .

Optionally, the thickness of the quantum well can be 2nm-3nm.

Optionally, the thickness of the quantum barrier may be 9nm-20nm.

Optionally, the number of layers of the quantum barrier is the same as that of the quantum wells, and the number of quantum wells may be 5-15.

Optionally, the thickness of the electron blocking layer may be 50nm˜150nm.

Optionally, the thickness of the P-type gallium nitride layer may be 105nm˜500nm.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (9)

1. a preparation method of light-emitting diode epitaxial wafer, is characterized in that, described preparation method comprises: growing a first undoped gallium nitride layer on the buffer layer stacked on the substrate; A colloidal crystal thin film is formed on the first undoped gallium nitride layer, the colloidal crystal thin film includes a plurality of organic particles arranged in an array on the first undoped gallium nitride layer, the organic particles The diameter is 0.5μm～1.8μm; depositing an oxide film on and between the plurality of organic particles; heating the plurality of organic particles, the plurality of organic particles are decomposed into gas and discharged from between the oxide film and the first undoped gallium nitride layer during the process of temperature rise, the A plurality of cavities arranged in an array are formed between the first undoped gallium nitride layer and the oxide film; growing a second undoped gallium nitride layer on the oxide film; An N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer are sequentially grown on the second undoped GaN layer to form an epitaxial wafer. 2. preparation method according to claim 1, is characterized in that, described preparation method also comprises: applying a laser to the oxide film, using the plurality of cavities to separate the first undoped gallium nitride layer from the second undoped gallium nitride layer; Etching the first undoped gallium nitride layer until the surface of the first undoped gallium nitride layer is flat to obtain a substrate stacked with a buffer layer. 3. The preparation method according to claim 1 or 2, wherein the growing the first undoped gallium nitride layer on the buffer layer stacked on the substrate comprises: providing a substrate stacked with a buffer layer; A first undoped gallium nitride layer is grown on the buffer layer. 4. The preparation method according to claim 1 or 2, wherein the growing the first undoped gallium nitride layer on the buffer layer stacked on the substrate comprises: growing a buffer layer on the substrate; A first undoped gallium nitride layer is grown on the buffer layer. 5. The preparation method according to claim 1 or 2, characterized in that, the colloidal crystal film is formed on the first undoped gallium nitride layer, and the colloidal crystal film includes arrays arranged on the first gallium nitride layer. A plurality of organic particles on an undoped gallium nitride layer, including: Dispersing the precursor in a solvent and reacting to generate the organic particles; The solvent is evaporated, and the organic particles are arranged in an array under the capillary action induced by the evaporation of the solvent to form the colloidal crystal film. 6. The preparation method according to claim 3, characterized in that, the material of the organic particles is polystyrene. 7. The preparation method according to claim 1 or 2, characterized in that the material of the oxide film is aluminum oxide or zinc oxide. 8. The preparation method according to claim 1 or 2, characterized in that the thickness of the oxide film is 0.5nm-50nm. 9. A light-emitting diode epitaxial wafer, said light-emitting diode epitaxial wafer comprising a buffer layer, an N-type gallium nitride layer, a multi-quantum well layer, an electron blocking layer and a P-type nitride nitride layer stacked on the substrate in sequence. Gallium layer, characterized in that the light-emitting diode epitaxial wafer further includes a first undoped gallium nitride layer, a colloidal crystal film, and an oxide film stacked between the buffer layer and the N-type gallium nitride layer and a second undoped gallium nitride layer, the first undoped gallium nitride layer is disposed on the buffer layer, and the colloidal crystal thin film includes an array arranged on the first undoped gallium nitride layer A plurality of organic particles on the organic particles, the diameter of the organic particles is 0.5 μm to 1.8 μm, the oxide film is arranged on the plurality of organic particles and between the plurality of organic particles, the second undoped A heterogallium nitride layer is disposed on the oxide film.