LED epitaxial structure and preparation method thereof and LED device

Abstract

The present invention provides an LED epitaxial structure and a preparation method thereof and an LED device. The LED epitaxial structure includes a substrate, a non-doped semiconductor layer, an N-type semiconductor layer, a multi-quantum well region, and a P-type semiconductor layer from bottom to top. The LED epitaxial structure also includes at least one group of electron-enriched layer groups arranged below the multi-quantum well region, and in each group of electron-enriched layer groups, multiple In-doped electron-enriched layers with In doping concentrations increasing from bottom to top are stacked; the multi-quantum well region includes multiple potential well layer groups and potential barrier layers stacked alternately, and in each group of potential well layer groups, multiple In-doped potential well layers with In doping concentrations decreasing from bottom to top are stacked. The possibility of introducing structural defects such as dislocations, stacking faults, V-type defects and pores due to stress mismatch in the epitaxial layer caused by In segregation is reduced, thereby enhancing the lattice quality; and the potential energy difference at both ends of the quantum well is increased, the recombination efficiency of electrons and holes is increased, and the luminous efficiency is further improved.

Description

Technical Field

[0001] The invention relates to the field of semiconductor light emitting devices, and in particular to an LED epitaxial structure and a preparation method thereof, and an LED device. Background Art

[0002] Light emitting diodes (LEDs), especially nitride light emitting diodes, have been widely used in the field of general lighting due to their high luminous efficiency.

[0003] At present, the In component in the quantum well of GaN-based blue light LED is relatively high, which easily causes In segregation. In addition, the mismatch stress in the epitaxial layer with high In doping concentration will introduce structural defects such as dislocations, stacking faults, V-shaped defects and pores, which will deteriorate the crystal quality and thus reduce the luminous efficiency. In addition, as the light-emitting layer becomes thicker, the increase in the In component will lead to an intensified polarization effect in the GaN material system. The larger polarization effect causes band distortion and a decrease in potential energy, which reduces the effective recombination area of ​​electrons and holes, further reducing the luminous efficiency. Summary of the invention

[0004] The object of the present invention is to provide an LED epitaxial structure and a preparation method thereof and an LED device.

[0005] The present invention provides an LED epitaxial structure, which comprises a substrate, a non-doped semiconductor layer, an N-type semiconductor layer, a multi-quantum well region, and a P-type semiconductor layer in order from bottom to top, and the LED epitaxial structure also comprises at least one group of electron-enriched layer groups arranged below the multi-quantum well region, and in each group of the electron-enriched layer groups, multiple In-doped electron-enriched layers are stacked and arranged with the In doping concentration increasing in order from bottom to top;

[0006] The multi-quantum well region includes a plurality of potential well layer groups and potential barrier layers which are alternately stacked. In each group of the potential well layer groups, multiple In-doped potential well layers are stacked with the In doping concentration decreasing from bottom to top.

[0007] As a further improvement of the present invention, the number of the electron-rich layer groups is 3 to 6, and the In doping concentration of the electron-rich layer varies cyclically between the multiple electron-rich layer groups.

[0008] As a further improvement of the present invention, each group of the electron-enriched layer groups is provided with 2 to 4 electron-enriched layers, and the electron-enriched layers are In a Ga (1-a) N, where 0.1<a<0.3.

[0009] As a further improvement of the present invention, 3 to 10 pairs of the potential well layer groups and the potential barrier layers which are alternately stacked are provided in the multi-quantum well region.

[0010] As a further improvement of the present invention, each group of the potential well layer groups is provided with 3 to 8 potential well layers, wherein the potential well layers are In b Ga (1-b) N, where 0.1<b<0.3.

[0011] As a further improvement of the present invention, the barrier layer is Al c Ga (1-c) N, where 0.1<c<0.3.

[0012] As a further improvement of the present invention, an Al-doped interface transition layer is further provided between each barrier layer and the potential well layer group below it, wherein the Al doping concentration in the interface transition layer is higher than the Al doping concentration in the barrier layer. d Ga (1-d) N, where c<d<0.3.

[0013] As a further improvement of the present invention, an insertion layer is provided below each group of the potential well layer groups, and its bandgap width is smaller than the bandgap width of the potential well layer. The insertion layer is an InN layer, and its thickness ranges from 0.5 to 1 nm.

[0014] The present invention further provides an LED device, characterized in that it comprises the above LED epitaxial structure, an N electrode and a P electrode, wherein the N electrode is ohmically connected to the N-type semiconductor layer, and the P electrode is ohmically connected to the P-type semiconductor layer.

[0015] The present invention also provides a method for preparing an LED epitaxial structure, comprising the steps of:

[0016] sequentially growing a non-doped semiconductor layer and a first N-type semiconductor layer on a substrate;

[0017] Growing multiple electron-rich layers doped with In to form a group of electron-rich layers, wherein the In doping concentration of each electron-rich layer increases in sequence of growth;

[0018] Growing multiple layers of In-doped potential well layers to form a group of potential well layer groups, wherein the In doping concentration of each potential well layer decreases in sequence of growth;

[0019] Growth barrier layer;

[0020] Alternating and repeatedly growing the potential well layer group and the potential barrier layer to form a multi-quantum well region;

[0021] A P-type semiconductor layer is grown.

[0022] As a further improvement of the present invention, the steps are also included:

[0023] Repeatedly grow 2 to 5 groups of the electron-rich layer groups on the electron-rich layer groups, and the In doping concentration of the electron-rich layer changes periodically between the multiple groups of the electron-rich layer groups.

[0024] As a further improvement of the present invention, “growing a multi-layer In-doped electron-rich layer” specifically includes:

[0025] Grow 2 to 4 layers of In a Ga (1-a) N forms a group of the electron-rich layer groups, wherein 0.1<a<0.3, and the In doping concentration increases in sequence of growth.

[0026] As a further improvement of the present invention, after growing the electron-rich layer group, the following steps are further included:

[0027] A layer of InN with a thickness ranging from 0.5 to 1 nm is grown to form an insertion layer.

[0028] As a further improvement of the present invention, 3 to 8 pairs of the potential well layer groups and the potential barrier layers are grown alternately.

[0029] As a further improvement of the present invention, “growing a multi-layer In-doped potential well layer” specifically includes:

[0030] Grow 3 to 8 layers of In b Ga (1-b) N forms a group of potential well layer groups, wherein 0.1<b<0.3, and the In doping concentration decreases in the order of growth.

[0031] As a further improvement of the present invention, the “growth barrier layer” specifically includes:

[0032] Growth Al c Ga (1-c) N forms a barrier layer, where 0.1<c<0.3.

[0033] As a further improvement of the present invention, before growing the barrier layer, the method further comprises the following steps:

[0034] Grow a layer of Al d Ga (1-d) N forms an interface transition layer, where c<d<0.3.

[0035] The beneficial effects of the present invention are as follows: by setting an electron-enriched layer with increasing In doping concentration and a potential well layer with decreasing In doping concentration, first, more electrons can be accumulated in the electron-enriched layer to provide electrons for the light-emitting layer, thereby improving the electron utilization rate; second, the possibility of introducing structural defects such as dislocations, stacking faults, V-shaped defects and pores due to stress mismatch in the epitaxial layer caused by In segregation is reduced, thereby enhancing the lattice quality; third, the potential energy difference at both ends of the quantum well is increased, the recombination efficiency of electrons and holes is increased, and the luminous efficiency is further improved. In addition, each barrier layer is also provided with an Al-doped interface transition layer, and the Al doping concentration in the interface transition layer is higher than the Al doping concentration in the barrier layer, thereby causing the Al-doped interface to move forward toward the potential well layer, forming a decreasing relationship of Al doping concentration between the interface transition layer and the barrier layer, thereby further enhancing the lattice quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of an LED epitaxial structure in one embodiment of the present invention.

[0037] Figure 2 It is a schematic flow chart of a method for preparing an LED epitaxial structure in one embodiment of the present invention.

[0038] Figures 3 to 10 It is a schematic diagram of each step of a method for preparing an LED epitaxial structure in one embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in combination with the specific implementation methods of this application and the corresponding drawings. Obviously, the described implementation methods are only part of the implementation methods of this application, not all of the implementation methods. Based on the implementation methods in this application, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0040] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0041] For ease of explanation, this document uses terms that represent spatial relative positions for description, such as "above", "below", "rear", "front", etc., to describe the relationship of one unit or feature shown in the drawings relative to another unit or feature. Terms of spatial relative position can include different orientations of the device in use or operation other than the orientation shown in the figure. For example, if the device in the figure is turned over, the unit described as being located "below" or "above" other units or features will be located "below" or "above" the other units or features. Therefore, the exemplary term "below" can encompass both the spatial orientations of below and above.

[0042] like Figure 1 As shown, the present invention provides an LED epitaxial structure, which includes a substrate 1, a non-doped semiconductor layer 2, an N-type semiconductor layer 3, a multi-quantum well region 6, and a P-type semiconductor layer 7 from bottom to top.

[0043] The substrate 1 is made of sapphire, silicon carbide, silicon or a composite substrate of the above materials, or other commonly used LED substrate materials.

[0044] The N-type semiconductor layer 3 and the P-type semiconductor layer 7 are any III-nitride-based semiconductor layers commonly used in the art, and the present invention does not impose any specific limitation on this.

[0045] In some embodiments of the present invention, a nitride buffer layer is further provided on the substrate 1 to reduce the lattice mismatch between the substrate 1 and the semiconductor layer and improve the growth quality of the epitaxial layer.

[0046] The LED epitaxial structure further includes at least one electron-enriched layer group 4 disposed below the multi-quantum well region 6. In each electron-enriched layer group 4, multiple In-doped electron-enriched layers 41 are stacked with the In doping concentration increasing from bottom to top.

[0047] Here, by providing an electron-enriched layer 41 with a gradually increasing In doping concentration, the In content is gradually increased, thereby reducing the possibility of introducing structural defects such as dislocations, stacking faults, V-shaped defects and pores due to stress mismatch in the epitaxial layer caused by In segregation, thereby enhancing the lattice quality and increasing the potential energy difference between the well and the barrier; and through the electron-enriched layer 41, more electrons can be accumulated in the electron-enriched layer 41 to provide electrons for the light-emitting layer, thereby improving the electron utilization rate.

[0048] Furthermore, the number of electron-enriched layer groups 4 is 3 to 6, and each electron-enriched layer group 4 is provided with 2 to 4 electron-enriched layers 41. The In doping concentration of the electron-enriched layer 41 varies periodically between multiple electron-enriched layer groups 4. The number of electron-enriched layer groups 4 and the number of electron-enriched layers 41 in each group are limited. On the one hand, it is avoided that there are too few electron-enriched layers 41, which prevents the formation of layers with gradually changing In concentrations and the inability to provide enough electron-enriched layers 41 to accumulate electrons. On the other hand, it is avoided that there are too many electron-enriched layers 41, which prevents the total thickness of the electron-enriched layers from being too thick, thereby making the polarization effect more obvious.

[0049] Furthermore, the electron-rich layer 41 is In a Ga (1-a) N, where 0.1<a<0.3.

[0050] Specifically, in this embodiment, six electron-rich layer groups 4 are provided, and each electron-rich layer group 4 includes three electron-rich layers 41 from bottom to top: a first electron-rich layer 41a, a second electron-rich layer 41b, and a third electron-rich layer 41c, which are In a1 Ga (1-a1) N、In a2 Ga (1-a2) N and In a3 Ga (1-a3) N, wherein 0.1<a1<a2<a3<0.3. In each electron-rich layer group 4, the first electron-rich layer 41a, the second electron-rich layer 41b and the third electron-rich layer 41c are periodically and repeatedly stacked in sequence, that is, the electron-rich layer 41 is formed in the order of the first electron-rich layer 41a, the second electron-rich layer 41b, the third electron-rich layer 41c, the first electron-rich layer 41a, the second electron-rich layer 41b, the third electron-rich layer 41c...

[0051] In this embodiment, the In doping concentration between the electron-rich layers 41 varies uniformly within each electron-rich layer group 4. In some other embodiments, the In doping concentration may also gradually vary according to a parabolic trend or an exponential trend, etc., and the present invention does not impose any specific restrictions on this, as long as an In doping concentration variation gradient is formed.

[0052] In some other embodiments of the present invention, a stress release layer is further grown between the N-type semiconductor layer 3 and the electron-rich layer group 4 to reduce lattice strain and reduce problems such as cracks or dislocations caused by lattice mismatch.

[0053] The multi-quantum well region 6 includes a plurality of alternately stacked potential well layer groups 61 and potential barrier layers 62 . In each potential well layer group 61 , a plurality of In-doped potential well layers 611 are stacked with the In doping concentration decreasing from bottom to top.

[0054] First, an electron-enriched layer 41 with increasing In concentration is set, and then a potential well layer 611 with decreasing In concentration is set thereon, thereby increasing the potential energy difference at both ends of a single quantum well, increasing the recombination efficiency of electrons and holes, and improving the luminous efficiency. Moreover, while increasing the potential energy difference, the In component is not increased, thereby reducing the band tilt and band distortion caused by the polarization effect.

[0055] Furthermore, 3 to 10 pairs of alternately stacked potential well layer groups 61 and potential barrier layers 62 are provided in the multi-quantum well region 6, and 3 to 8 potential well layers 611 are provided in each potential well layer group 61. The number of quantum wells and the number of potential well layers 611 in each potential well layer group 61 are limited. On the one hand, it is avoided that the multi-quantum well region 6 as the main light-emitting region has too few layers, and the electrons and holes cannot be fully recombined, which reduces the light-emitting brightness. On the other hand, it is avoided that the multi-quantum well region 6 is too thick, which makes the polarization effect more obvious, resulting in more dislocations, poor lattice quality, and affecting the light-emitting efficiency.

[0056] Furthermore, the potential well layer 611 is In b Ga (1-b) N, where 0.1<b<0.3.

[0057] Specifically, in this embodiment, the multi-quantum well region 6 includes 10 pairs of potential well layer groups 61 and barrier layers 62 that are alternately stacked, and each potential well layer group 61 has three potential well layers 611 from bottom to top: a first potential well layer 611, a second potential well layer 611, and a third potential well layer 611, which are In b1 Ga (1-ab1) N、In b2 Ga (1-b2) N and In b3 Ga (1-b3) N, wherein 0.1<b3<b2<b1<0.3. In each potential well layer group 61, the first potential well layer 611, the second potential well layer 611 and the third potential well layer 611 are repeatedly stacked, that is, the multi-quantum well region 6 is formed in the order of the first potential well layer 611, the second potential well layer 611, the third potential well layer 611, the barrier layer 62, the first potential well layer 611, the second potential well layer 611, the third potential well layer 611, the barrier layer 62, ...

[0058] In this embodiment, the In doping concentration between the electron enrichment layers 41 varies uniformly within each potential well layer group 61. In some other embodiments, the In doping concentration may also vary gradually according to a parabolic trend or an exponential trend, etc., and the present invention does not impose any specific limitation on this, as long as an In doping concentration variation gradient is formed.

[0059] In some other embodiments of the present invention, an insertion layer 5 is further disposed under each potential well layer group 61 , and the bandgap width of the insertion layer 5 is smaller than the bandgap width of the potential well layer 611 .

[0060] By inserting an insertion layer 5 with a small bandgap width under the potential well layer group 61, the energy band tilt between the potential well layer 611 and the barrier layer 62 is reduced, and the spatial wave function overlap is increased, thereby effectively limiting the Stark effect and further increasing the luminous efficiency.

[0061] Specifically, in this embodiment, the insertion layer 5 is an InN layer, and its thickness ranges from 0.5 to 1 nm.

[0062] In this embodiment, the barrier layer 62 is Al c Ga (1-c) N, where 0.1<c<0.3.

[0063] Furthermore, in some other embodiments of the present invention, an Al-doped interface transition layer 621 is provided between each barrier layer 62 and the potential well layer group 61 therebelow, and the Al doping concentration in the interface transition layer 621 is higher than the Al doping concentration in the barrier layer 62. Thus, on the one hand, by doping the interface transition layer 621 with Al, the potential energy height of the barrier layer 62 is further increased to achieve the effect of blocking electrons; on the other hand, the Al-doped interface is moved forward toward the potential well layer 611, and a decreasing relationship of Al doping concentration is formed between the interface transition layer 621 and the barrier layer 62, thereby alleviating problems such as deterioration of the lattice quality of the barrier layer 62 due to Al doping and band distortion caused by polarization effects, so as to reduce electron overflow and increase luminescence efficiency.

[0064] Specifically, in this embodiment, the interface transition layer 621 is Al d Ga (1-d) N, where c<d<0.3.

[0065] In some embodiments of the present invention, the LED epitaxial structure further includes conventional LED epitaxial layer structures such as a current blocking layer, which will not be described in detail herein.

[0066] The present invention further provides an LED device, which includes the above LED epitaxial structure, an N electrode and a P electrode, wherein the N electrode is ohmically connected to the N-type semiconductor layer 3 , and the P electrode is ohmically connected to the P-type semiconductor layer 7 .

[0067] like Figure 2 As shown, the present invention also provides a method for preparing an LED epitaxial structure, comprising the steps of:

[0068] S1: Figure 3 As shown, a non-doped semiconductor layer 2 and a first N-type semiconductor layer 3 are sequentially grown on a substrate 1 .

[0069] After pretreatment, the substrate 1 is placed in a reaction chamber of a metal organic chemical vapor deposition device to grow the non-doped semiconductor layer 2 and the first N-type semiconductor layer 3. In some embodiments of the present invention, a nitride buffer layer is also grown on the substrate 1.

[0070] S2: Figure 4 As shown, multiple electron-rich layers 41 doped with In are grown to form a group of electron-rich layers 4, and the In doping concentration of each electron-rich layer 41 increases in sequence according to the growth order.

[0071] In some embodiments of the present invention, the method further comprises the steps of:

[0072] like Figure 5 As shown, 2 to 5 groups of electron-rich layer groups 4 are repeatedly grown on the electron-rich layer group 4 , and the In doping concentration of the electron-rich layer 41 varies cyclically between the multiple groups of electron-rich layer groups 4 .

[0073] Specifically, grow 2 to 4 layers of In a Ga (1-a) N forms a group of electron-rich layer groups 4, where 0.1<a<0.3, and the In doping concentration increases in the order of growth.

[0074] like Figure 6 As shown, in some embodiments of the present invention, after growing the electron-enriched layer group 4, the following steps are further included:

[0075] A layer of InN with a thickness ranging from 0.5 to 1 nm is grown to form the insertion layer 5 .

[0076] Furthermore, the growth temperature of the insertion layer 5 is 5-10° C. lower than the temperature at which the potential well layer 611 is subsequently grown.

[0077] S3: Figure 7 As shown, multiple layers of In-doped potential well layers 611 are grown to form a group of potential well layer groups 61, and the In doping concentration of each potential well layer 611 decreases in sequence of growth.

[0078] Specifically, 3 to 8 layers of In are grown. b Ga (1-b) N forms a potential well layer group 61, wherein 0.1<b<0.3, and the In doping concentration decreases in the order of growth.

[0079] S4: Figure 8 As shown, a barrier layer 62 is grown.

[0080] Specifically, the growth of Al c Ga (1-c) N forms a barrier layer 62, where 0.1<c<0.3.

[0081] In some embodiments of the present invention, before growing the barrier layer 62, the following steps are also included:

[0082] Grow a layer of Al d Ga (1-d) N forms an interface transition layer 621, where c<d<0.3.

[0083] S5: Fig. 9 As shown, the multi-quantum well region 6 is formed by alternately and repeatedly growing a potential well layer group 61 and a potential barrier layer 62 .

[0084] Specifically, 3 to 8 pairs of well layer groups 61 and barrier layers 62 are grown alternately.

[0085] S6: Fig.10 As shown, a P-type semiconductor layer 7 is grown.

[0086] In some embodiments of the present invention, the method for preparing an LED epitaxial structure further includes the step of manufacturing a conventional LED epitaxial layer structure such as a current blocking layer, which will not be described in detail herein.

[0087] In summary, the present invention provides an electron-enriched layer with increasing In doping concentration and a potential well layer with decreasing In doping concentration. First, more electrons can be accumulated in the electron-enriched layer to provide electrons for the light-emitting layer, thereby improving the electron utilization rate; second, the possibility of introducing structural defects such as dislocations, stacking faults, V-shaped defects and pores due to stress mismatch in the epitaxial layer caused by In segregation is reduced, thereby enhancing the lattice quality; third, the potential energy difference at both ends of the quantum well is increased, the recombination efficiency of electrons and holes is increased, and the luminous efficiency is further improved. In addition, each barrier layer is also provided with an Al-doped interface transition layer, and the Al doping concentration in the interface transition layer is higher than the Al doping concentration in the barrier layer, thereby causing the Al-doped interface to move forward toward the potential well layer, forming a decreasing relationship of Al doping concentration between the interface transition layer and the barrier layer, further enhancing the lattice quality.

[0088] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0089] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. An LED epitaxial structure, which comprises, from bottom to top, a substrate, a non-doped semiconductor layer, an N-type semiconductor layer, a multi-quantum well region, and a P-type semiconductor layer, characterized in that: The LED epitaxial structure further includes at least one group of electron-enriched layer groups disposed below the multi-quantum well region, and in each group of the electron-enriched layer groups, multiple In-doped electron-enriched layers are stacked and arranged with the In doping concentration increasing from bottom to top; the number of the electron-enriched layer groups is 3 to 6 groups, and each group of the electron-enriched layer groups is provided with 2 to 4 electron-enriched layers, and the In doping concentration of the electron-enriched layers varies cyclically between the multiple groups of the electron-enriched layer groups; The multi-quantum well region includes a plurality of alternately stacked potential well layer groups and potential barrier layers, and in each group of the potential well layer groups, multiple In-doped potential well layers are stacked with the In doping concentration decreasing from bottom to top; 3 to 10 pairs of alternately stacked potential well layer groups and potential barrier layers are provided in the multi-quantum well region; and each group of the potential well layer groups is provided with 3 to 8 layers of the potential well layers.

2. The LED epitaxial structure according to claim 1, characterized in that: The electron-rich layer is In a Ga (1-a) N, where 0.1<a<0.

3.

3. The LED epitaxial structure according to claim 1, characterized in that: The potential well layer is In b Ga (1-b) N, where 0.1<b<0.

3.

4. The LED epitaxial structure according to claim 1, characterized in that: The barrier layer is Al c Ga (1-c) N, where 0.1<c<0.

3.

5. The LED epitaxial structure according to claim 4, characterized in that: An Al-doped interface transition layer is also provided between each barrier layer and the potential well layer group below it. The Al doping concentration in the interface transition layer is higher than the Al doping concentration in the barrier layer. d Ga (1-d) N, where c<d<0.

3.

6. The LED epitaxial structure according to claim 1, characterized in that: An insertion layer is provided below each potential well layer group, and its bandgap width is smaller than that of the potential well layer. The insertion layer is an InN layer, and its thickness ranges from 0.5 to 1 nm.

7. An LED device, characterized in that: It comprises the LED epitaxial structure according to any one of claims 1 to 6, an N electrode and a P electrode, wherein the N electrode is ohmically connected to the N-type semiconductor layer, and the P electrode is ohmically connected to the P-type semiconductor layer.

8. A method for preparing an LED epitaxial structure, characterized in that: Includes steps: sequentially growing a non-doped semiconductor layer and a first N-type semiconductor layer on a substrate; Growing multiple electron-rich layers doped with In to form a group of electron-rich layers, wherein the In doping concentration of each electron-rich layer increases in sequence according to the growth order; Repeatedly growing 2 to 5 groups of the electron-rich layer groups on the electron-rich layer group, wherein the In doping concentration of the electron-rich layer changes periodically between the multiple groups of the electron-rich layer groups; Growing multiple layers of In-doped potential well layers to form a group of potential well layer groups, wherein the In doping concentration of each potential well layer decreases in sequence of growth; Growth barrier layer; Alternately and repeatedly growing 3 to 8 pairs of the potential well layer groups and the potential barrier layers to form a multi-quantum well region; A P-type semiconductor layer is grown.

9. The method for preparing an LED epitaxial structure according to claim 8, characterized in that: "Growing a multi-layer In-doped electron-rich layer" specifically includes: Grow 2 to 4 layers of In a Ga (1-a) N forms a group of the electron-rich layer groups, wherein 0.1<a<0.3, and the In doping concentration increases in sequence of growth.

10. The method for preparing an LED epitaxial structure according to claim 8, characterized in that: After growing the electron-rich layer group, the following steps are also included: A layer of InN with a thickness ranging from 0.5 to 1 nm is grown to form an insertion layer.

11. The method for preparing an LED epitaxial structure according to claim 8, characterized in that: “Growing a multilayer In-doped potential well layer” specifically includes: Grow 3 to 8 layers of In b Ga (1-b) N forms a group of potential well layer groups, wherein 0.1<b<0.3, and the In doping concentration decreases in the order of growth.

12. The method for preparing an LED epitaxial structure according to claim 10, characterized in that: The "growth barrier layer" specifically includes: Growth Al c Ga (1-c) N forms a barrier layer, where 0.1<c<0.

3.

13. The method for preparing an LED epitaxial structure according to claim 12, characterized in that: Before growing the barrier layer, the method further comprises the steps of: Grow a layer of Al d Ga (1-d) N forms an interface transition layer, where c<d<0.3.

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