Semiconductor light emitting structure and preparation method thereof

Abstract

The present invention provides a semiconductor light-emitting structure and a preparation method thereof, wherein the semiconductor light-emitting structure comprises: a photonic crystal layer located on a side of an active layer away from a semiconductor substrate layer, the photonic crystal layer comprising a first layer and a second layer, the second layer extending into the first layer and covering a surface of the first layer away from the active layer, the refractive index of the second layer being higher than that of the first layer; a Bragg reflector located on a side of the photonic crystal layer away from the active layer, the Bragg reflector comprising a third layer and a fourth layer stacked alternately, the refractive index of the third layer being higher than that of the fourth layer; a transition layer located between the Bragg reflector and the photonic crystal layer, the transition layer being in contact with the third layer, the Al component in the transition layer being greater than the Al component in the second layer and less than the Al component in the third layer, and the Al component in the transition layer decreasing from the Bragg reflector toward the photonic crystal layer. The light extraction efficiency of the semiconductor light-emitting structure is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a semiconductor light-emitting structure and a preparation method thereof. Background Art

[0002] Semiconductor lasers are widely used in the modern optoelectronics industry. Introducing embedded periodic photonic crystals into semiconductor lasers is a general method to effectively control the light field mode and manufacture various high-performance semiconductor lasers. The light output performance (mode, divergence angle, slope efficiency, etc.) of semiconductor lasers with photonic crystals is often closely related to the processing quality of the photonic crystals. Producing photonic crystals that meet theoretical design requirements (morphology, size, and roughness) is the top priority for exerting the photonic crystal effect and achieving high-performance lasing. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is how to improve the light extraction efficiency of a semiconductor light emitting structure, thereby providing a semiconductor light emitting structure and a method for preparing the same.

[0004] The present application provides a semiconductor light-emitting structure, comprising: a semiconductor substrate layer; an active layer located on one side of the semiconductor substrate layer; a photonic crystal layer located on a side of the active layer away from the semiconductor substrate layer, the photonic crystal layer comprising a first layer and a second layer, the second layer extending into the first layer and covering a surface of the first layer on a side away from the active layer, the refractive index of the second layer being higher than the refractive index of the first layer; a Bragg reflector located on a side of the photonic crystal layer away from the active layer, the Bragg reflector comprising a third layer and a fourth layer stacked alternately, the refractive index of the third layer being higher than the refractive index of the fourth layer; a transition layer located between the Bragg reflector and the photonic crystal layer, the transition layer being in contact with the third layer, the Al component in the transition layer being greater than the Al component in the second layer and less than the Al component in the third layer, and the Al component in the transition layer decreasing from the Bragg reflector toward the photonic crystal layer.

[0005] Optionally, the thickness of the transition layer is smaller than the thickness of the third layer.

[0006] Optionally, the transition layer has a thickness of 0.01 micrometer to 0.05 micrometer.

[0007] Optionally, the material of the second layer includes Al x1 Ga 1-x1 As, the material of the third layer includes Al doped with conductive ions x3 Ga 1-x3 As, the material of the transition layer includes Al x2 Ga 1-x2As, x2 is greater than x1 and less than x3.

[0008] Optional, x1 is 0.3~0.45; x2 is 0.40~0.70; x3 is 0.75~0.98.

[0009] Optionally, the second layer extending into the first layer has a gap inside.

[0010] Optionally, it further includes: a carrier transport layer located between the semiconductor substrate layer and the active layer, and the doping type of the carrier transport layer is opposite to the doping type of the Bragg reflector.

[0011] The present application also provides a method for preparing a semiconductor light-emitting structure, comprising: forming an active layer on one side of a semiconductor substrate layer; forming a photonic crystal layer on a side of the active layer away from the semiconductor substrate layer, the photonic crystal layer comprising a first layer and a second layer, the second layer extending into the first layer and covering a surface of the first layer away from the active layer, the refractive index of the second layer being higher than the refractive index of the first layer; forming a transition layer on a side of the photonic crystal layer away from the active layer; forming a Bragg reflector on a side of the transition layer away from the photonic crystal layer, the Bragg reflector comprising a third layer and a fourth layer alternately stacked, the refractive index of the third layer being higher than the refractive index of the fourth layer; wherein the transition layer contacts the third layer, the Al component in the transition layer is greater than the Al component in the second layer and less than the Al component in the third layer, and the Al component in the transition layer decreases from the Bragg reflector toward the photonic crystal layer.

[0012] Optionally, the step of forming the photonic crystal layer includes: forming a first layer on a side of the active layer facing away from the semiconductor substrate layer; forming a groove, the groove extending from a surface of the first layer facing away from the active layer to the first layer; and forming the second layer in the groove and on a surface of the first layer facing away from the active layer.

[0013] Optionally, during the process of forming the second layer, a gap is formed inside the second layer in the groove.

[0014] Optionally, the process for forming the transition layer is an organic metal vapor chemical deposition process; the steps for forming the transition layer include a plurality of sub-cycle processes performed in sequence; each sub-cycle process includes: step S1: introducing a group III gas source into the chamber to form a first adsorption film; step S2: extracting the remaining group III gas source from the chamber; step S3: introducing a group V gas source into the chamber to form a second adsorption film on the surface of the first adsorption film, and the second adsorption film reacts with the first adsorption film to form a sub-transition layer; step S4: extracting the remaining group V gas source from the chamber.

[0015] Optionally, in each sub-cycle process, the time for which the Group III gas source is introduced into the chamber is less than or equal to 5 seconds, and the time for which the Group V gas source is introduced into the chamber is less than or equal to 5 seconds.

[0016] Optionally, a growth rate of the sub-transition layer in a direction parallel to the surface of the semiconductor substrate layer is greater than a growth rate in a direction perpendicular to the surface of the semiconductor substrate layer.

[0017] The technical solution of the present invention has the following beneficial effects:

[0018] In the semiconductor light-emitting structure provided by the technical solution of the present invention, since the transition layer is located between the Bragg reflector and the photonic crystal layer, the transition layer is in contact with the third layer, the Al component in the transition layer is greater than the Al component in the second layer and less than the Al component in the third layer, and the Al component in the transition layer decreases from the Bragg reflector toward the photonic crystal layer. Therefore, the transition layer can balance the stress in the second layer extending into the first layer, block the influence of the stress in the second layer extending into the first layer on the growth process of the Bragg reflector, optimize the growth quality at the interface between the photonic crystal layer and the Bragg reflector, improve the growth quality of the Bragg reflector, and improve the light extraction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 and Figure 2 A scanning electron microscope image of the preparation process of a semiconductor light-emitting structure;

[0021] Figures 3 to 7 It is a structural schematic diagram of the preparation process of a semiconductor light-emitting structure in one embodiment of the present invention. DETAILED DESCRIPTION

[0022] A method for preparing a semiconductor laser with a photonic crystal includes: forming a carrier transport layer on one side of a semiconductor substrate layer; forming an active layer on the side of the carrier transport layer away from the semiconductor substrate layer; forming a photonic crystal layer on the side of the active layer away from the Bragg reflector; forming a Bragg reflector on the side of the photonic crystal layer away from the active layer. Forming the photonic crystal layer includes: forming a first layer on the side of the active layer away from the semiconductor substrate layer; forming periodically arranged grooves, the grooves extending from the surface of the first layer on the side away from the active layer to the first layer; forming a second layer in the grooves, the refractive index of the second layer being higher than the refractive index of the first layer.

[0023] Since the growth rate of the second layer is anisotropic during the formation of the second layer in the groove, Figure 1 and Figure 2 During the closing process of the groove, a gap W is formed, and after the groove is closed, the stress at the top of the groove generates a defect L. During the formation of the Bragg reflector 10, the stress defect in the second layer will continue to extend in the Bragg reflector 10, resulting in a decrease in the growth quality of the Bragg reflector 10 and a decrease in the light extraction efficiency of the semiconductor light emitting structure.

[0024] On this basis, the present invention provides a semiconductor light-emitting structure and a preparation method thereof, which improves the light extraction efficiency of the semiconductor light-emitting structure.

[0025] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0027] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] An embodiment of the present invention provides a semiconductor light emitting structure, referring to Figure 7 ,include:

[0029] Semiconductor substrate layer 100;

[0030] An active layer 120 located on one side of the semiconductor substrate layer 100;

[0031] a photonic crystal layer 130 located on a side of the active layer 120 away from the semiconductor substrate layer 100, the photonic crystal layer 130 comprising a first layer 1300 and a second layer 1302, the second layer 1302 extending into the first layer 1300 and covering a surface of the first layer 1300 away from the active layer 120, the refractive index of the second layer 1302 being higher than the refractive index of the first layer 1300;

[0032] a Bragg reflector 150 located on a side of the photonic crystal layer 130 away from the active layer 120 , wherein the Bragg reflector 150 comprises a third layer and a fourth layer stacked alternately, and a refractive index of the third layer is higher than a refractive index of the fourth layer;

[0033] A transition layer 140 is located between the Bragg reflector 150 and the photonic crystal layer 130, wherein the transition layer 140 is in contact with the third layer, wherein the Al component in the transition layer 140 is greater than the Al component in the second layer 1302 and less than the Al component in the third layer, and wherein the Al component in the transition layer 140 decreases gradually from the Bragg reflector 150 toward the photonic crystal layer 130.

[0034] In this embodiment, since the transition layer 140 is located between the Bragg reflector 150 and the photonic crystal layer 130, the transition layer 140 is in contact with the third layer, the Al component in the transition layer 140 is greater than the Al component in the second layer 1302 and less than the Al component in the third layer, and the Al component in the transition layer 140 decreases from the Bragg reflector 150 toward the photonic crystal layer 130, the transition layer 140 can balance the stress in the second layer 1302 extending into the first layer 1300, block the influence of the stress in the second layer 1302 extending into the first layer 1300 on the growth process of the Bragg reflector 150, optimize the growth quality at the interface between the photonic crystal layer 130 and the Bragg reflector 150, improve the growth quality of the Bragg reflector 150, and improve the light extraction efficiency of the semiconductor light-emitting structure.

[0035] In this embodiment, the semiconductor light emitting structure includes a surface emitting semiconductor laser.

[0036] In this embodiment, the first layer 1300 and the second layer 1302 are periodically arranged in a direction parallel to the surface of the semiconductor substrate layer 100. The photonic crystal layer 130 can modulate the light field to increase the intensity of the central wavelength of the light emitted by the semiconductor light emitting structure.

[0037] In one embodiment, the thickness of the transition layer 140 is less than the thickness of the third layer. The thickness of the transition layer 140 is not too large, and the overall thickness of the semiconductor light emitting structure can be well controlled, which is conducive to improving the integration of the semiconductor structure. The thickness of the transition layer 140 is not too small, so that the transition layer 140 can better block the stress in the second layer 1302 in the first layer 1300 from extending to the Bragg reflector 150.

[0038] In one embodiment, the transition layer 140 has a thickness of 0.01 micrometer to 0.05 micrometer, for example, 0.02 micrometer, 0.03 micrometer, 0.04 micrometer or 0.05 micrometer.

[0039] In one embodiment, the material of the second layer 1302 includes Al x1 Ga 1-x1 As, the material of the third layer includes Al doped with conductive ions x3 Ga 1-x3 As, the material of the transition layer 140 includes Al x2 Ga 1-x2 As, x1 is greater than x2 and less than x3. For example: x1 is 0.3~0.45; x2 is 0.40~0.70; x3 is 0.75~0.98.

[0040] In one embodiment, the transition layer 140 is not doped with conductive ions.

[0041] In one embodiment, the photonic crystal layer 130 includes a first layer 1300 and a second layer 1302. The material of the first layer 1300 includes GaAs, and the material of the second layer includes Al. x1 Ga 1-x1 The refractive index of the second layer 1302 is higher than that of the first layer 1300. In one embodiment, the first layer 1300 and the second layer 1302 are not doped with conductive ions.

[0042] In one embodiment, the second layer 1302 extending into the first layer 1300 has gaps 1303 inside. Multiple gaps 1303 are arranged periodically, and the gaps 1303 are used to transmit light of a specific wavelength, so that the wavelength of the light emitted by the semiconductor light emitting structure is more concentrated. In other embodiments, the photonic crystal layer 130 may not have gaps 1303.

[0043] In one embodiment, the Al component in the transition layer 140 changes from a first component to a second component in the thickness direction of the transition layer 140, the difference between the first component and the Al component in the second layer 1302 is less than or equal to 0.01, and the difference between the second component and the Al component in the third layer is less than or equal to 0.01.

[0044] In one embodiment, the semiconductor light emitting structure further includes: a carrier transport layer 110 located between the semiconductor substrate layer 100 and the active layer 120, and the doping type of the carrier transport layer 110 is opposite to the doping type of the Bragg reflector 150. For example, the doping type of the Bragg reflector 150 is P-type, and the doping type of the carrier transport layer 110 is N-type.

[0045] In one embodiment, there is no Bragg reflector between the semiconductor substrate layer 100 and the active layer 120. The light emitted by the active layer 120 is transmitted to the Bragg reflector 150 and reflected by the Bragg reflector 150, and then emitted from the semiconductor substrate 100 to the side of the semiconductor substrate 100 away from the active layer 120, and the photonic crystal layer 130 selects the wavelength of the light.

[0046] In one embodiment, the refractive index of the third layer is higher than that of the fourth layer, and the Al component in the third layer is greater than the Al component in the fourth layer. For example, the material of the fourth layer is Al doped with conductive ions. x4 Ga 1-x4 As, x3 is greater than x4. The doping type of the conductive ions in the fourth layer is consistent with that of the conductive ions in the third layer.

[0047] In one embodiment, the Bragg reflector 150 includes a first Bragg reflection group and a second Bragg reflection group, the second Bragg reflection group is located on a side of the first Bragg reflection group away from the transition layer 140, the number of third layers in the first Bragg reflection group is much smaller than the number of third layers in the second Bragg reflection group, the number of fourth layers in the first Bragg reflection group is much smaller than the number of fourth layers in the second Bragg reflection group. The concentration of conductive ions in the fourth layer in the first Bragg reflection group is smaller than the concentration of conductive ions in the fourth layer in the second Bragg reflection group, and the concentration of conductive ions in the third layer in the first Bragg reflection group is smaller than the concentration of conductive ions in the third layer in the second Bragg reflection group.

[0048] In one embodiment, the number of layers of the third layer in the first Bragg reflection group is multiple layers and the number of layers of the fourth layer in the first Bragg reflection group is multiple layers. In one embodiment, the concentration of conductive ions in the multiple third layers in the first Bragg reflection group increases along the direction from the active layer to the semiconductor substrate layer, and the concentration of conductive ions in the multiple fourth layers in the first Bragg reflection group increases along the direction from the active layer to the semiconductor substrate layer. In other embodiments, the concentration of conductive ions in the multiple third layers in the first Bragg reflection group is the same, and the concentration of conductive ions in the multiple fourth layers in the first Bragg reflection group is the same.

[0049] The present application also provides a method for preparing a semiconductor light-emitting structure, comprising: forming an active layer on one side of a semiconductor substrate layer; forming a photonic crystal layer on a side of the active layer away from the semiconductor substrate layer, the photonic crystal layer comprising a first layer and a second layer, the second layer extending into the first layer and covering a surface of the first layer away from the active layer, the refractive index of the second layer being higher than the refractive index of the first layer; forming a transition layer on a side of the photonic crystal layer away from the active layer; forming a Bragg reflector on a side of the transition layer away from the photonic crystal layer, the Bragg reflector comprising a third layer and a fourth layer alternately stacked, the refractive index of the third layer being higher than the refractive index of the fourth layer; wherein the transition layer contacts the third layer, the Al component in the transition layer is greater than the Al component in the second layer and less than the Al component in the third layer, and the Al component in the transition layer decreases from the Bragg reflector toward the photonic crystal layer.

[0050] Reference below Figures 3 to 7 Introduces the preparation process for forming semiconductor structures.

[0051] refer to Figure 3 , a carrier transport layer 110 is formed on one side of the semiconductor substrate layer 100 ; and an active layer 120 is formed on a side of the carrier transport layer 110 that is away from the semiconductor substrate layer 100 .

[0052] In this embodiment, the present invention further includes: forming a photonic crystal layer on a side of the active layer 120 away from the semiconductor substrate layer 100. The step of forming the photonic crystal layer includes: referring to Figure 3 A first layer 1300 is formed on a side of the active layer 120 away from the semiconductor substrate layer 100 .

[0053] In one embodiment, the process of forming the first layer 1300 is a deposition process, such as an organic metal chemical vapor deposition process. The material of the first layer 1300 is as described in the above embodiment.

[0054] refer to Figure 4 The step of forming the photonic crystal layer further includes: forming a groove 1301 , wherein the groove 1301 extends from a surface of the first layer 1300 facing away from the active layer 120 to the first layer 1300 .

[0055] In one embodiment, the process of forming the groove 1301 is an etching process.

[0056] refer to Figure 5The step of forming the photonic crystal layer 130 also includes: forming a second layer 1302 in the groove 1301 and on a surface of the first layer 1300 facing away from the active layer 120 , wherein the refractive index of the second layer 1302 is higher than the refractive index of the first layer 1300 .

[0057] In one embodiment, the process for forming the second layer 1302 is a deposition process, such as an organic metal chemical vapor deposition process. The material of the second layer 1302 is as described in the above embodiment.

[0058] In one embodiment, during the process of forming the second layer 1302, a gap 1303 is formed inside the second layer 1302 in the groove 1301. In other embodiments, the gap 1303 may not be formed.

[0059] refer to Figure 6 A transition layer 140 is formed on the side of the photonic crystal layer 130 away from the active layer 120. The Al component in the transition layer 140 is greater than the Al component in the second layer 1302. The Al component in the transition layer 140 decreases from the transition layer 140 toward the photonic crystal layer 130.

[0060] In one embodiment, the process for forming the transition layer 140 is an organic metal vapor chemical deposition process. The steps for forming the transition layer 140 include a plurality of sub-cycle processes performed in sequence; each sub-cycle process includes: step S1: using a group III gas source to pass into the chamber to form a first adsorption film; step S2: extracting the remaining group III gas source from the chamber; step S3: using a group V gas source to pass into the chamber to form a second adsorption film on the surface of the first adsorption film, and the second adsorption film reacts with the first adsorption film to form a sub-transition layer; step S4: extracting the remaining group V gas source from the chamber.

[0061] In one embodiment, in each sub-cycle process, the time for which the Group III gas source is introduced into the chamber is less than or equal to 5 seconds, and the time for which the Group V gas source is introduced into the chamber is less than or equal to 5 seconds.

[0062] In one embodiment, the transition layer 140 is formed at a temperature of 700 degrees Celsius to 800 degrees Celsius, and a chamber pressure of 40 mbar to 60 mbar.

[0063] In one embodiment, the growth rate of the sub-transition layer parallel to the surface of the semiconductor substrate layer 100 is greater than the growth rate perpendicular to the surface of the semiconductor substrate layer 100. The growth state of the sub-transition layer tends to two-dimensional growth, which improves the epitaxial quality of the sub-transition layer and helps to prevent the stress defects in the second layer 1302 from extending in the direction away from the active layer.

[0064] In one embodiment, the growth rate of the sub-transition layer along a direction parallel to the surface of the semiconductor substrate layer 100 is much greater than the growth rate along a direction perpendicular to the surface of the semiconductor substrate layer 100. For example, the growth rate of the sub-transition layer along a direction parallel to the surface of the semiconductor substrate layer 100 is greater than 10 times the growth rate along a direction perpendicular to the surface of the semiconductor substrate layer 100.

[0065] refer to Figure 7 A Bragg reflector 150 is formed on the side of the transition layer 140 away from the photonic crystal layer 130, wherein the Bragg reflector 150 includes a third layer and a fourth layer stacked alternately, wherein the refractive index of the third layer is higher than that of the fourth layer. The transition layer 140 is in contact with the third layer.

[0066] The Al composition in the transition layer 140 is greater than the Al composition in the second layer 1302 and less than the Al composition in the third layer, and the Al composition in the transition layer 140 decreases from the Bragg reflector 150 toward the photonic crystal layer.

[0067] Regarding the material of the Bragg reflector 150 , refer to the above-mentioned embodiment.

[0068] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A semiconductor light emitting structure, characterized in that: include: Semiconductor substrate layer; an active layer located on one side of the semiconductor substrate layer; a photonic crystal layer located on a side of the active layer away from the semiconductor substrate layer, the photonic crystal layer comprising a first layer and a second layer, the first layer having a groove therein, the groove extending from a surface of the first layer on a side away from the active layer to the first layer; the second layer extending into the first layer, located in the groove and covering a surface of the first layer on a side away from the active layer, the refractive index of the second layer being higher than the refractive index of the first layer; a Bragg reflector located on a side of the photonic crystal layer away from the active layer, the Bragg reflector comprising a third layer and a fourth layer stacked alternately, the refractive index of the third layer being higher than the refractive index of the fourth layer; A transition layer is located between the Bragg reflector and the photonic crystal layer, the transition layer is in contact with the third layer, the Al component in the transition layer is greater than the Al component in the second layer and less than the Al component in the third layer, and the Al component in the transition layer decreases from the Bragg reflector toward the photonic crystal layer.

2. The semiconductor light emitting structure according to claim 1, characterized in that: The thickness of the transition layer is smaller than the thickness of the third layer.

3. The semiconductor light emitting structure according to claim 2, characterized in that: The thickness of the transition layer is 0.01 micrometer to 0.05 micrometer.

4. The semiconductor light emitting structure according to claim 1, characterized in that: The material of the second layer includes Al x1 Ga 1-x1 As, the material of the third layer includes Al doped with conductive ions x3 Ga 1-x3 As, the material of the transition layer includes Al x2 Ga 1-x2 As, x2 is greater than x1 and less than x3.

5. The semiconductor light emitting structure according to claim 4, characterized in that: x1 is 0.3~0.45; x2 is 0.40~0.70; x3 is 0.75~0.

98.

6. The semiconductor light emitting structure according to claim 1, characterized in that: The second layer extending into the first layer has a void therein.

7. The semiconductor light emitting structure according to claim 1, characterized in that: Also includes: The carrier transport layer is located between the semiconductor substrate layer and the active layer, and the doping type of the carrier transport layer is opposite to the doping type of the Bragg reflector.

8. A method for preparing a semiconductor light-emitting structure, characterized in that: include: forming an active layer on one side of the semiconductor substrate layer; forming a photonic crystal layer on a side of the active layer away from the semiconductor substrate layer, the photonic crystal layer comprising a first layer and a second layer, the second layer extending into the first layer and covering a surface of the first layer away from the active layer, and the refractive index of the second layer being higher than that of the first layer; forming a transition layer on a side of the photonic crystal layer away from the active layer; A Bragg reflector is formed on a side of the transition layer away from the photonic crystal layer, wherein the Bragg reflector comprises a third layer and a fourth layer stacked alternately, and a refractive index of the third layer is higher than a refractive index of the fourth layer; The transition layer contacts the third layer, an Al component in the transition layer is greater than an Al component in the second layer and less than an Al component in the third layer, and the Al component in the transition layer decreases from the Bragg reflector toward the photonic crystal layer; The step of forming the photonic crystal layer includes: forming a first layer on the side of the active layer away from the semiconductor substrate layer; forming a groove, the groove extending from the surface of the first layer on the side away from the active layer to the first layer; forming the second layer in the groove and on the surface of the first layer on the side away from the active layer.

9. The method for preparing a semiconductor light emitting structure according to claim 8, characterized in that: During the formation of the second layer, a void is formed inside the second layer in the groove.

10. The method for preparing a semiconductor light emitting structure according to claim 8, characterized in that: The process of forming the transition layer is an organic metal vapor chemical deposition process; The step of forming the transition layer includes a plurality of sub-cycle processes performed sequentially; each sub-cycle process includes: Step S1: introducing a Group III gas source into the chamber to form a first adsorption film; Step S2: extracting the remaining Group III gas source from the chamber; Step S3: introducing a Group V gas source into the chamber to form a second adsorption film on the surface of the first adsorption film, and the second adsorption film reacts with the first adsorption film to form a sub-transition layer; Step S4: extracting the remaining Group V gas source from the chamber.

11. The method for preparing a semiconductor light emitting structure according to claim 10, characterized in that: In each sub-cycle process, the time for which the Group III gas source is introduced into the chamber is less than or equal to 5 seconds, and the time for which the Group V gas source is introduced into the chamber is less than or equal to 5 seconds.

12. The method for preparing a semiconductor light emitting structure according to claim 10, characterized in that: The growth rate of the sub-transition layer in a direction parallel to the surface of the semiconductor substrate layer is greater than the growth rate in a direction perpendicular to the surface of the semiconductor substrate layer.

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