LED epitaxial wafer, epitaxial growth method and LED chip

Abstract

The present invention provides an LED epitaxial wafer, an epitaxial growth method and an LED chip, wherein a substrate and an N-type layer, a multi-quantum well layer and a P-type layer sequentially deposited on the substrate are provided, wherein the N-type layer is a LT-AlN layer, a PALE-AlN layer, a GaN quantum dot and an n-Al x Ga （1‑x） The periodic superlattice structure of the N layer is deposited sequentially. Due to the distribution of multiple GaN quantum dots in the PALE‑AlN layer and the n‑Al x Ga （1‑x） The interface of the N layer can provide the electrons required for radiative recombination. The introduction of quantum dots can effectively bind electrons and slow down the electrons injected into the active area of ​​the multi-quantum well layer without affecting hole injection, thereby improving the carrier injection efficiency of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of LEDs, and in particular to an LED epitaxial wafer, an epitaxial growth method and an LED chip. Background Art

[0002] Nitride is a new type of semiconductor material for the development of microelectronic devices and optoelectronic devices. The research and application of nitride is currently a hot topic in global semiconductor research. It has properties such as wide direct band gap, strong atomic bonds, high thermal conductivity, good chemical stability (almost not corroded by any acid) and strong radiation resistance, and has broad prospects in the application of optoelectronics, high-temperature high-power devices and high-frequency microwave devices.

[0003] However, in the development of both InGaN and AlGaN optoelectronic devices, the problem of high-density defects due to the lack of homogeneous substrates has been encountered. In addition, experiments have shown that in nitride materials, the effective mass of electrons and holes is very different, making it very easy for electrons to overflow the active area, while holes are difficult to inject, causing the recombination process of electrons and holes to often occur in P-GaN rather than the active area.

[0004] Due to its bandgap width (3.4eV to 6.2eV), AlGaN materials are more widely used in GaN light-emitting diodes (LEDs) and other devices as electron barrier layers (EBL) to block electrons. However, the presence of EBL will also hinder the injection of holes to a certain extent, and EBL requires AlGaN materials with a high Al content. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide an LED epitaxial wafer, an epitaxial growth method and an LED chip, which aims to slow down the electrons injected into the active area of ​​the multi-quantum well layer without affecting the hole injection, thereby improving the carrier injection efficiency of the device.

[0006] According to an embodiment of the present invention, an LED epitaxial wafer includes a substrate and an N-type layer, a multi-quantum well layer and a P-type layer sequentially deposited on the substrate, wherein the N-type layer is a LT-AlN layer, a PALE-AlN layer, a GaN quantum dot and an n-Al x Ga （1-x） A periodic superlattice structure in which N layers are deposited sequentially, 0≤x<1;

[0007] During the deposition of the GaN quantum dots, only a Ga source is introduced to form Ga droplets on the PALE-AlN layer;

[0008] After the Ga droplets are formed, the N source is immediately introduced;

[0009] In an N source environment, the temperature is increased and annealing is performed to form GaN quantum dots.

[0010] Furthermore, in the step of introducing only Ga source and forming Ga droplets on the PALE-AlN layer, the growth time is 5s to 18s and the growth temperature is 500°C to 650°C.

[0011] Furthermore, in the step of immediately introducing the N source after the Ga droplets are formed, NH 3 The introduction time is 8s~30s, and the growth temperature is lower than the growth temperature when the Ga droplets are formed.

[0012] Furthermore, in the step of heating and annealing in an N source environment to form GaN quantum dots, 3 Under the environment, the temperature is raised to 850℃~1200℃ and annealed, and the annealing time is 10s~60s.

[0013] Furthermore, the thickness of the LT-AlN layer is 5 nm to 30 nm, and the growth temperature is 300° C. to 800° C.

[0014] Furthermore, the thickness of the PALE-AlN layer is 30nm-500nm, and the growth temperature is 900°C-1200°C.

[0015] Furthermore, the number of cycles of the PALE-AlN layer is 6 to 50, one PALE cycle is 8 s to 25 s, TMAl is continuously introduced into the reaction chamber, and NH 3 In pulse form, NH 3 The on time should be shorter than the off time.

[0016] Furthermore, the n-Al x Ga （1-x） The thickness of the N layer is 10nm~100nm, the doping element is Si, and the electron concentration formed by doping is 1×10 17 cm -3 ~1×10 20 cm -3 .

[0017] According to an embodiment of the present invention, an epitaxial growth method of an LED epitaxial wafer is used to prepare the above-mentioned LED epitaxial wafer, and the epitaxial growth method comprises:

[0018] A growth substrate and an N-type layer, a multi-quantum well layer and a P-type layer sequentially deposited on the substrate, wherein the N-type layer is a LT-AlN layer, a PALE-AlN layer, a GaN quantum dot and an n-Al x Ga （1-x） N layers of superlattice structure deposited sequentially, 0≤x<1;

[0019] During the deposition of the GaN quantum dots, only a Ga source is introduced to form Ga droplets on the PALE-AlN layer;

[0020] After the Ga droplets are formed, the N source is immediately introduced;

[0021] In an N source environment, the temperature is increased and annealing is performed to form GaN quantum dots.

[0022] An LED chip according to an embodiment of the present invention includes the above-mentioned LED epitaxial wafer.

[0023] Compared with the prior art: the LED epitaxial wafer provided by the present invention replaces the traditional buffer layer by the LT-AlN layer and the PALE-AlN layer, which can release tensile stress and prevent the epitaxial film from cracking. At the same time, it can reduce the lattice difference between the entire N-type layer and the substrate, further reduce the crystal defect density, improve the crystal quality of the epitaxial material, and reduce the non-radiative recombination efficiency; in addition, the PALE method can effectively inhibit the gas phase pre-reaction and enhance the migration ability of Al atoms on the surface, and provide a template for the subsequent growth of GaN quantum dots; finally, the introduction of GaN quantum dots can achieve electron deceleration, because the size of the quantum dots in all directions is close to the Bohr radius of the electron. Inside the quantum dots, the movement of the electrons is restricted in the three-dimensional direction, resulting in the distribution of the electron state density presenting a delta function distribution. The state density distribution is no longer continuous, and the electrons can only radiate in the transition between finite and determined energy levels, so the non-radiative recombination of the carriers will be weakened, thereby bringing about a higher internal quantum efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the structure of an N-type layer of an LED epitaxial wafer provided by an embodiment of the present invention;

[0025] Figure 2 A flowchart of an implementation method of an epitaxial growth method for an LED epitaxial wafer provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0027] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0029] See also Figure 1 , is a schematic diagram of the structure of an N-type layer of an LED epitaxial wafer provided in an embodiment of the present invention, the LED epitaxial wafer comprises a substrate and an N-type layer 1, a multi-quantum well layer and a P-type layer sequentially deposited on the substrate, the N-type layer is a LT-AlN layer 11, a PALE-AlN layer 12, a GaN quantum dot 13 and an n-Al x Ga （1-x） The N layer 14 is a super lattice structure deposited in sequence, and the N-type layer has an electron deceleration effect.

[0030] Among them, the LT-AlN layer 11 is an AlN layer grown at a low temperature. Specifically, the thickness of the LT-AlN layer 11 is 5nm~30nm. Exemplarily, the thickness of the LT-AlN layer 11 is 5nm, 10nm, 15nm, 20nm, 25nm or 30nm, etc., but not limited to this. It should be noted that the "~" in "5nm~30nm" represents a value between 5nm and 30nm and endpoint values ​​5nm and 30nm. The meaning expressed by the subsequent appearance of this symbol is consistent and will not be repeated. The growth temperature of the LT-AlN layer 11 is 300℃~800℃.

[0031] In one embodiment of the present invention, the thickness of the PALE-AlN layer 12 is 30nm~500nm. For example, the thickness of the PALE-AlN layer 12 is 30nm, 100nm, 200nm, 300nm, 400nm or 500nm, but not limited thereto. The growth temperature is 900℃~1200℃. It should be noted that the PALE-AlN layer 12 is an AlN layer prepared by a PALE (Pulsed Atomic Layer Epitaxy) process. More specifically, the number of cycles of the PALE-AlN layer 12 is 6~50, and one PALE cycle is 8s~25s. TMAl is continuously introduced into the reaction chamber, and NH 3 In pulse form, NH 3 The on time should be shorter than the off time.

[0032] Furthermore, in the process of depositing GaN quantum dots 13, Ga droplets are first formed on the PALE-AlN layer 12, wherein the growth time is 5s to 18s, the growth temperature is 500°C to 650°C, and no NH 3 ;

[0033] At the base of the Ga droplet, NH 3 , the introduction time is 8s~30s, and the growth temperature is lower than the growth temperature when the Ga droplets are formed;

[0034] In NH 3 Under the environment, the temperature is raised to 850℃~1200℃ and annealed, and the annealing time is 10s~60s. It can be understood that the GaN quantum dots 13 are distributed in the PALE-AlN layer 12 and the n-Al x Ga （1-x） At the interface of N layer 14.

[0035] In one embodiment of the present invention, n-Al x Ga （1-x） The thickness of the N layer 14 is 10 nm to 100 nm. For example, n-Al x Ga （1-x） The thickness of the N layer 14 is 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm, but is not limited thereto. The doping element is Si, and the electron concentration formed by doping is 1×10 17 cm -3 ~1×10 20 cm -3 .

[0036] In one embodiment of the present invention, n-Al x Ga （1-x）In the N layer 14, 0≤x<1, in the N-type layer 1, the LT-AlN layer 11, the PALE-AlN layer 12, the GaN quantum dots 13 and the n-Al x Ga （1-x） The N layer 14 is sequentially deposited for 4 to 15 cycles, and illustratively, the number of cycles is 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14.

[0037] Correspondingly, the embodiment of the present invention also provides an epitaxial growth method of an LED epitaxial wafer, which is used to prepare the above-mentioned LED epitaxial wafer, referring to Figure 2 , is a flow chart of an implementation method of an epitaxial growth method of an LED epitaxial wafer provided by an embodiment of the present invention, which specifically includes the following steps:

[0038] S1. Provide a substrate and clean it.

[0039] The substrate may be a PSS AlN-coated substrate, a sapphire substrate or a SIC substrate. Specifically, the substrate is heated to 1100° C. and subjected to a hydrogenation treatment for 5 minutes to remove surface impurities.

[0040] S2. Growing an N-type layer on the substrate.

[0041] Specifically, firstly, TMAl is introduced to grow a LT-AlN layer, the thickness of the LT-AlN layer is 5nm~30nm, and the growth temperature is 300℃~800℃;

[0042] Then TMAl and NH 3 , grow a PALE-AlN layer, the thickness of the PALE-AlN layer is 30nm~500nm, the growth temperature is 900℃~1200℃, it should be noted that the number of cycles of the PALE-AlN layer is 6~50, one PALE cycle is 8s~25s, TMAl is always introduced into the reaction chamber, NH 3 In pulse form, NH 3 The access time should be shorter than the closing time;

[0043] Further, Ga droplets were formed on the PALE-AlN layer, wherein the growth time was 5s-18s, the growth temperature was 500℃-650℃, and no NH 3 ;

[0044] At the base of the Ga droplet, NH 3 , the introduction time is 8s~30s, and the growth temperature is lower than the growth temperature when the Ga droplets are formed;

[0045] In NH 3In an environment, the temperature is raised to 850°C~1200°C and annealed for 10s~60s to obtain GaN quantum dots;

[0046] Finally, TMAl, TEGa, and SiH 4 Growth of n-Al x Ga （1-x） N layer, n-Al x Ga （1-x） The thickness of the N layer is 10nm~100nm, the doping element is Si, and the electron concentration formed by doping is 1×10 17 cm -3 ~1×10 20 cm -3 .

[0047] S3, growing a multi-quantum well layer on a side of the N-type layer away from the substrate.

[0048] Specifically, TEGa, TMIn, SiH 4 The total thickness of the grown multi-quantum well layer is 140 nm, wherein the growth temperature of the quantum well layer is 780° C., and the growth temperature of the quantum barrier layer is 890° C.

[0049] S4, growing a P-type layer on a side of the multi-quantum well layer away from the substrate.

[0050] Specifically, TEGa and CP are introduced. 2 Mg growth P-type GaN layer, thickness 0.4μm, growth temperature 965℃, Mg concentration 2E19 / cm 3 .

[0051] It should be noted that the above steps are all completed in MOCVD equipment, and the MO sources used include trimethyl gallium TEGa, triethyl gallium TEGa, trimethyl TMIn, bismuth magnesium (Cp 2 Mg), trimethylaluminum (TMAl), TEGa and TEGa as Ga sources, and silane (SiH 4 ), ammonia (NH 3 )、H 2 、N 2 , where NH 3 is the N source, H 2 、N 2 is the carrier gas, and the N-type and P-type doping sources are silane SiH 4 and Magnesium CP 2 Mg.

[0052] In summary, the present invention provides an LED epitaxial wafer, an epitaxial growth method and an LED chip, by providing a substrate and an N-type layer, a multi-quantum well layer and a P-type layer sequentially deposited on the substrate, wherein the N-type layer is a LT-AlN layer, a PALE-AlN layer, a GaN quantum dot and an n-Al x Ga （1-x） The periodic superlattice structure of the N layer is deposited sequentially. Due to the distribution of multiple GaN quantum dots on the PALE-AlN layer and n-Al x Ga （1-x） The interface of the N layer can provide the electrons required for radiative recombination. The introduction of quantum dots can effectively bind electrons and slow down the electrons injected into the active area of ​​the multi-quantum well layer without affecting hole injection, thereby improving the carrier injection efficiency of the device.

[0053] The present invention will be further described below with specific embodiments:

[0054] Example 1

[0055] The epitaxial growth method of the LED epitaxial wafer in this embodiment 1 comprises the following steps:

[0056] (1) Provide a substrate and clean it.

[0057] The substrate is a PSS-coated AlN substrate. Specifically, the substrate is heated to 1100° C. and subjected to a hydrogenation treatment for 5 minutes to remove surface impurities.

[0058] (2) Growing an N-type layer on a PSS-coated AlN substrate.

[0059] Specifically, TMAl is first introduced to grow a LT-AlN layer, the thickness of the LT-AlN layer is 10 nm, and the growth temperature is 500° C.;

[0060] Introduce TMAl and NH 3 , grow PALE-AlN layer, PALE cycle is 10, cycle time is 10s, NH 3 The injection time is 4 s and the growth temperature is 1000°C;

[0061] TEGa was introduced at a flow rate of 12 µmol / min, and NH 3 , Ga droplets were grown on the PALE-AlN layer, with a growth time of 12 s, a growth temperature of 580 °C, and a growth pressure of 40 Torr;

[0062] TEGa was introduced at a flow rate of 12 µmol / min. On the basis of the above Ga droplets, 1800 sccm of NH 3 , the growth time is 10s, and then the temperature is quickly cooled to 450℃ to grow GaN quantum dots.

[0063] The TEGa flow rate was reduced to 8 µmol / min, and other growth parameters were kept unchanged. On this basis, 1800 sccm of NH 3 In the environment, the temperature is raised to 900°C and annealed for 15 seconds;

[0064] Finally, TMAl, TEGa, and SiH 4 Growth of n-Al x Ga （1-x） N layer, n-Al x Ga （1-x） The thickness of the N layer is 20 nm, the doping element is Si, and the electron concentration formed by doping is 2E19 / cm 3 The growth temperature is 1085℃, and the period of the entire superlattice N-type layer is 5, that is, the N-type layer consists of 5 sequentially deposited LT-AlN layers, PALE-AlN layers, GaN quantum dots and n-Al x Ga （1-x） It consists of N layers.

[0065] (3) Growing a multi-quantum well layer on the side of the N-type layer facing away from the substrate.

[0066] Specifically, TEGa, TMIn, SiH 4 The total thickness of the grown multi-quantum well layer is 140 nm, wherein the growth temperature of the quantum well layer is 780° C., and the growth temperature of the quantum barrier layer is 890° C.

[0067] (4) Growing a P-type layer on the side of the multi-quantum well layer facing away from the substrate.

[0068] Specifically, TEGa and CP are introduced. 2 Mg growth P-type GaN layer, thickness 0.4μm, growth temperature 965℃, Mg concentration 2E19 / cm 3 .

[0069] Example 2

[0070] This embodiment 2 also provides an epitaxial growth method for an LED epitaxial wafer, which differs from the embodiment 1 in that: (2) an N-type layer is grown on a PSS-coated AlN substrate. Specifically, TMAl, NH 3 , grow PALE-AlN layer, PALE cycle is 30, cycle time is 10s, NH 3 The injection time is 4 s and the temperature is 1000°C.

[0071] Example 3

[0072] This embodiment 3 also provides an epitaxial growth method for an LED epitaxial wafer, which differs from the embodiment 1 in that: (2) an N-type layer is grown on a PSS-coated AlN substrate. Specifically, TMAl, NH 3 , PALE-AlN layer was grown, the PALE cycle was 50, the cycle time was 10s, NH 3 The injection time is 4 s and the temperature is 1000°C.

[0073] Example 4

[0074] This embodiment 4 also provides an epitaxial growth method for an LED epitaxial wafer, which differs from the embodiment 1 in that: (2) an N-type layer is grown on a PSS-coated AlN substrate. Specifically, TEGa is introduced at a flow rate of 20 μmol / min, and NH 3 , Ga droplets were grown on the PALE-AlN layer, with a growth time of 12 s, a growth temperature of 580 °C, and a growth pressure of 40 Torr;

[0075] TEGa was introduced at a flow rate of 20 µmol / min. On the basis of the above Ga droplets, 1800 sccm of NH 3 , the growth time is 10s, and then the temperature is quickly cooled to 450℃ to grow GaN quantum dots.

[0076] Example 5

[0077] This embodiment 5 also provides an epitaxial growth method for an LED epitaxial wafer, which differs from the embodiment 1 in that: (2) an N-type layer is grown on a PSS-coated AlN substrate. Specifically, TEGa is introduced at a flow rate of 12 µmol / min, and NH 3 , Ga droplets were grown on the PALE-AlN layer with a growth time of 12s, a growth temperature of 650℃ and a growth pressure of 40Torr.

[0078] Example 6

[0079] This embodiment 6 also provides an epitaxial growth method for an LED epitaxial wafer, which differs from the embodiment 1 in that: (2) an N-type layer is grown on a PSS-coated AlN substrate. Specifically, TEGa is introduced at a flow rate of 12 μmol / min. On the basis of the above-mentioned Ga droplets, 1800 sccm of NH 3 , the growth time is 10s, and then the temperature is quickly cooled to 400℃ to grow GaN quantum dots.

[0080] Example 7

[0081] This embodiment 7 also provides an epitaxial growth method for an LED epitaxial wafer, which differs from the embodiment 1 in that: (2) an N-type layer is grown on a PSS-coated AlN substrate. Specifically, the TEGa flow rate is reduced to 12 µmol / min, and other growth parameters are kept unchanged. On this basis, 1800 sccm of NH 3 Under the environment, the temperature is raised to 900℃ and annealed, and the annealing time is 15s.

[0082] Example 8

[0083] This embodiment 8 also provides an epitaxial growth method for an LED epitaxial wafer, which differs from the embodiment 1 in that: (2) an N-type layer is grown on a PSS AlN-coated substrate. Specifically, the entire superlattice N-type layer has 15 periods, that is, the N-type layer is composed of 15 sequentially deposited LT-AlN layers, PALE-AlN layers, GaN quantum dots, and n-Al x Ga （1-x） It consists of N layers.

[0084] Comparative Example 1

[0085] Comparative Example 1 provides a conventional epitaxial growth method for LED epitaxial wafers, which is as follows:

[0086] (1) Provide a PSS-coated AlN substrate, heat it to 1100°C, and perform a hydrogenation treatment for 5 minutes to remove surface impurities, thereby cleaning the substrate.

[0087] (2) TEGa is introduced to grow a buffer layer with a thickness of 2 nm and a growth temperature of 850°C.

[0088] (3) TEGa is introduced to grow a U-type GaN layer with a thickness of 2300nm and a growth temperature of 1125℃.

[0089] (4) Introducing TEGa and SiH 4 Grow N-type GaN layer with a thickness of 2000nm at a growth temperature of 1085℃ and SiH 4 The concentration is 2E19 / cm 3 .

[0090] (5) Pass in TEGa, TMIn, SiH 4 The total thickness of the grown multi-quantum well layer is 140 nm, wherein the growth temperature of the quantum well layer is 780° C., and the growth temperature of the quantum barrier layer is 890° C.

[0091] (6) Introducing TEGa and CP 2 Mg growth P-type GaN layer, thickness 0.4μm, growth temperature 965℃, Mg concentration 2E19 / cm 3 .

[0092] The LED chips finally prepared in Examples 1 to 8 and the LED chips in Comparative Example 1 were tested for light efficiency under the same conditions. The results are shown in the following table:

[0093]

[0094] It can be found from the table that the luminous efficiency of the LED chips prepared in the embodiments of the present invention is improved to varying degrees compared with that in comparative example 1. Among them, the luminous efficiency of the LED chip prepared in embodiment 1 is the best, and the luminous efficiency is improved by 0.88% compared with that in comparative example 1.

[0095] It can be understood that after adding the N-type layer with electron deceleration effect, by using LT-AlN layer, PALE-AlN layer, GaN quantum dots and n-Al x Ga （1-x） The periodic superlattice structure of the N layer deposited in sequence is used as the N-type electron injection layer, and GaN quantum dots are inserted at the interface of the AlN and AlGaN superlattices to form a multi-periodic superlattice interface quantum dot structure, which mainly changes the structure of the typical N-type electron injection layer (n-GaN) in the prior art. The benefits are that, first, LT-AlN and PALE-AlN can reduce the lattice mismatch between the substrate and the multi-quantum well layer, and reduce the dislocation density of the AlGaN material; the PALE method can enhance the migration ability of Al atoms on the substrate surface, reduce the possibility of pre-reaction, and is conducive to improving the crystal quality of the epitaxial layer; second, by growing n-AlGaN, it can not only increase the electrons required for radiation recombination for the multi-quantum well layer, but also cover and bury the quantum dots to protect the quantum dots; third, in the GaN quantum dot material (also known as zero-dimensional material), the size in three dimensions is equivalent to the de Broglie wavelength of the electron, or even smaller, so the electron movement is bound in three dimensions, which can significantly slow down the electrons, and at the same time will not hinder the injection efficiency of holes, thereby improving the recombination efficiency of carriers.

[0096] An embodiment of the present invention further provides an LED chip, comprising the LED epitaxial wafer in any of the above embodiments.

[0097] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An LED epitaxial wafer, It is characterized in that The invention comprises a substrate and an N-type layer, a multi-quantum well layer and a P-type layer sequentially deposited on the substrate, wherein the N-type layer is a LT-AlN layer, a PALE-AlN layer, a GaN quantum dot and an n-Al x Ga （1-x） A periodic superlattice structure in which N layers are deposited sequentially, 0≤x<1; In the process of depositing the GaN quantum dots, firstly, only a Ga source is introduced to form Ga droplets on the PALE-AlN layer, wherein the growth time is 5s to 18s and the growth temperature is 500° C. to 650° C.; After the Ga droplets are formed, the N source is immediately introduced, wherein NH 3 , the introduction time is 8s~30s, and the growth temperature is lower than the growth temperature when the Ga droplets are formed; In the N source environment, the temperature is raised and annealed to form GaN quantum dots. 3 Under the environment, the temperature is raised to 850℃~1200℃ and annealed, and the annealing time is 10s~60s.

2. The LED epitaxial wafer according to claim 1, It is characterized in that The thickness of the LT-AlN layer is 5nm-30nm, and the growth temperature is 300°C-800°C.

3. The LED epitaxial wafer according to claim 1, It is characterized in that The thickness of the PALE-AlN layer is 30nm-500nm, and the growth temperature is 900°C-1200°C.

4. The LED epitaxial wafer according to claim 3, It is characterized in that The number of cycles of the PALE-AlN layer is 6 to 50, and one PALE cycle is 8 s to 25 s. TMAl is continuously introduced into the reaction chamber. NH 3 In pulse form, NH 3 The on time should be shorter than the off time.

5. The LED epitaxial wafer according to claim 1, It is characterized in that Said The thickness is 10nm~100nm, the doping element is Si, and the electron concentration formed by doping is .

6. A method for epitaxial growth of LED epitaxial wafers, It is characterized in that For preparing the LED epitaxial wafer according to any one of claims 1 to 5, the epitaxial growth method comprises: A growth substrate and an N-type layer, a multi-quantum well layer and a P-type layer sequentially deposited on the substrate, wherein the N-type layer is a LT-AlN layer, a PALE-AlN layer, a GaN quantum dot and an n-Al x Ga （1-x） N layers of superlattice structure deposited sequentially, 0≤x<1; During the deposition of the GaN quantum dots, only a Ga source is introduced to form Ga droplets on the PALE-AlN layer; After the Ga droplets are formed, the N source is immediately introduced; In an N source environment, the temperature is increased and annealing is performed to form GaN quantum dots.

7. An LED chip, It is characterized in that The LED epitaxial wafer comprises the LED epitaxial wafer as described in any one of claims 1 to 5.

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