Laser active layer epitaxial structure and its growth method and laser

Abstract

This invention provides an epitaxial structure of the active layer of a laser, its growth method, and the laser itself, applicable to a vertical-cavity surface-emitting laser. The epitaxial structure includes: an energy barrier layer, a well layer, and a confinement layer; wherein, a first confinement layer and a second confinement layer are located on opposite sides of the active layer; the first confinement layer is connected to the first energy barrier layer; the second confinement layer is connected to the second energy barrier layer; between the first energy barrier layer and the second energy barrier layer, there is a periodic structure consisting of a first well layer and a third energy barrier layer from bottom to top, and a second well layer; the periodic structure includes at least one periodic unit, and each periodic unit includes alternating first well layers and third energy barrier layers; the energy barrier layer includes an energy barrier vertical layer and an energy barrier gradient layer. By setting the energy barrier layer as an energy barrier vertical layer and an energy barrier gradient layer with a gradient structure, the thickness of the energy barrier layer is reduced, thereby increasing the volume of the well layer, improving the carrier recombination probability in the well layer, and thus reducing the possibility of electron leakage, thereby improving the internal quantum efficiency of the laser.

Description

Technical Field

[0001] This invention relates to the field of semiconductor lasers, and in particular to an active layer epitaxial structure for a laser, its growth method, and a laser. Background Technology

[0002] A VCSEL (Vertical Cavity Surface Emitting Laser) consists of an interconnected p-type Bragg reflector, an active layer, and an n-type Bragg reflector. The p-type Bragg reflector provides holes to the active layer, and the n-type Bragg reflector provides electrons to the active layer. Carriers are injected from the confinement layer of the active layer, transported to the energy barrier layer in the active layer via diffusion and drift, and then captured and recombinated by well layers in the active layer to generate light.

[0003] However, the vertical structure of the energy barrier layer and the wellbore may cause electron leakage in the VCSEL. Electron leakage refers to electrons that are transported to the p-type Bragg reflector without undergoing radiative recombination in the wellbore, where they recombine with holes in the p-type Bragg reflector, resulting in electron leakage. The vertical structure's impact on electron leakage is mainly manifested in the smaller wellbore volume, which allows a large number of electrons to bypass the wellbore and directly cross to the p-type Bragg reflector, causing electron leakage. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an active layer epitaxial structure for a laser, a growth method thereof, and a laser. By setting the barrier layer as a barrier vertical layer and a barrier gradient layer with a gradient structure, the thickness of the barrier layer is reduced, thereby increasing the well volume, thereby improving the carrier recombination probability in the well layer, and thus reducing the possibility of electron leakage, so as to improve the internal quantum efficiency of the laser.

[0005] In a first aspect, embodiments of the present invention provide an epitaxial structure for the active layer of a laser, applied to a vertical-cavity surface-emitting laser. The epitaxial structure includes: a barrier layer, a well layer, and a confinement layer; wherein, a first confinement layer and a second confinement layer are located on opposite sides of the active layer; the first confinement layer is connected to the first barrier layer; the second confinement layer is connected to the second barrier layer; between the first barrier layer and the second barrier layer, there is a periodic structure consisting of a first well layer and a third barrier layer from bottom to top, and a second well layer; the periodic structure includes at least one periodic unit, and each periodic unit includes alternating first well layers and third barrier layers; the barrier layer includes a barrier vertical layer and a barrier gradient layer; the confinement layer is used to block excessive carriers from continuously crossing the well layer and the barrier layer; wherein, the carriers include electrons and holes; the barrier vertical layer is used to block carriers from directly entering the next well layer from one well layer; the barrier gradient layer is used to reduce the thickness of the barrier layer so that the volume of the well layer is relatively increased to accommodate more carriers; the well layer is used to allow electrons and holes to merge so that electrons and holes recombine into photons.

[0006] Furthermore, the first barrier layer includes a first barrier vertical layer and a first barrier gradient layer connected from bottom to top; the second barrier layer includes a second barrier gradient layer and a second barrier vertical layer connected from bottom to top; and the third barrier layer includes a third barrier gradient layer, a third barrier vertical layer and a fourth barrier gradient layer connected from bottom to top.

[0007] Furthermore, the energy barrier gradient layer uses linearly gradient AlGaAs, in which the proportion of Al atoms is 0-20% and the proportion of Ga atoms is 1-80%.

[0008] Furthermore, the energy barrier gradient layer has a linear gradient structure and is epitaxially grown according to a preset temperature, preset pressure, and preset crystal growth rate; wherein, the preset temperature and preset pressure are controlled by a metal-organic chemical vapor deposition device; and the preset crystal growth rate is controlled by a mass flow controller.

[0009] Furthermore, the growth rate of the extensional growth of the energy barrier gradient layer varies linearly, and the growth rate is equal to the slope of the energy barrier gradient layer.

[0010] Furthermore, the confinement layer is made of AlGaAs, in which Al atoms account for 35% and Ga atoms account for 65%.

[0011] Furthermore, the energy barrier layer is made of AlGaAs, in which Al atoms account for 20% and Ga atoms account for 80%.

[0012] Furthermore, the well layer uses InGaAs material, in which In atoms account for 10% and Ga atoms account for 90% of the confinement layer.

[0013] Secondly, embodiments of the present invention provide a method for growing an epitaxial structure of an active layer of a laser, applied to a vertical cavity surface-emitting laser, comprising: step S1, forming a first barrier layer on a first confinement layer; step S2, forming a first well layer on the first barrier layer; step S3, forming a third barrier layer on the first well layer; step S4, repeating steps S2 to S3 cyclically until a periodic structure of a predetermined number of periodic units is formed, and forming a second well layer on the finally formed third barrier layer; step S5, forming a second barrier layer on the second well layer; and step S6, forming a second confinement layer on the second barrier layer.

[0014] Thirdly, embodiments of the present invention provide a laser, comprising: the epitaxial structure of the laser active layer described above, and further comprising a p-type electrode, an n-type electrode, a substrate, an n-type Bragg reflector layer, a p-type Bragg reflector layer, and an oxide layer, wherein the substrate, the n-type Bragg reflector layer, the active layer, and the p-type Bragg reflector layer are connected sequentially from bottom to top, the p-type electrode is placed on the p-type Bragg reflector layer, and the n-type electrode is placed on the substrate.

[0015] This invention provides an epitaxial structure of the active layer of a laser, its growth method, and a laser, applicable to a vertical-cavity surface-emitting laser. The epitaxial structure includes: a barrier layer, a well layer, and a confinement layer; wherein, a first confinement layer and a second confinement layer are located on opposite sides of the active layer; the first confinement layer is connected to the first barrier layer; the second confinement layer is connected to the second barrier layer; between the first barrier layer and the second barrier layer, there is a periodic structure consisting of a first well layer and a third barrier layer from bottom to top, and a second well layer; the periodic structure includes at least one periodic unit, and each periodic unit includes alternating first well layers and third barrier layers; the barrier layer includes a barrier vertical layer and a barrier gradient layer; the confinement layer is used to block excessive carriers from continuously crossing the well layer and the barrier layer; wherein, the carriers include electrons and holes; the barrier vertical layer is used to block carriers from directly entering the next well layer from one well layer; the barrier gradient layer is used to reduce the thickness of the barrier layer so that the volume of the well layer is relatively increased to accommodate more carriers; the well layer is used to allow electrons and holes to recombine into photons. In this approach, by setting the energy barrier layer as an energy barrier vertical layer and a gradient energy barrier layer with a gradient structure, the thickness of the energy barrier layer is reduced, thereby increasing the well volume relatively, which in turn increases the carrier recombination probability in the well layer and reduces the possibility of electron leakage, thereby improving the internal quantum efficiency of the laser.

[0016] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings.

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 The structure-band diagram of the active layer of a conventional vertical cavity surface-emitting laser provided by this invention;

[0020] Figure 2 The present invention provides a conventional active layer carrier recombination diagram for a vertical cavity surface-emitting laser;

[0021] Figure 3 This is a schematic diagram of the epitaxial structure of the active laser layer provided in Embodiment 1 of the present invention;

[0022] Figure 4 This is a composite diagram of active layer carriers provided in Embodiment 1 of the present invention;

[0023] Figure 5 This is a schematic diagram of the energy barrier layer epitaxial structure provided in Embodiment 1 of the present invention;

[0024] Figure 6 This is a material schematic diagram of the epitaxial structure of the laser active layer provided in Embodiment 1 of the present invention;

[0025] Figure 7 This is the energy band diagram of the epitaxial structure of the active layer of the laser provided in Embodiment 1 of the present invention;

[0026] Figure 8 Here are the structure-band diagrams for two other active layer epitaxial structures provided in Embodiment 2 of the present invention;

[0027] Figure 9 This is a flowchart of the growth method for the active layer epitaxial structure of a laser provided in Embodiment 3 of the present invention;

[0028] Figure 10 This is a schematic diagram of the laser structure provided in Embodiment 4 of the present invention.

[0029] Icons: 1-Block layer; 2-Well layer; 3-Confinement layer; 4-Active layer; 5-Block vertical layer; 6-Block gradient layer; 7-P-type electrode; 8-N-type electrode; 9-Substrate; 10-N-type Bragg reflector layer; 11-P-type Bragg reflector layer; 12-Oxide layer; 101-First barrier layer; 102-Second barrier layer; 103-Third barrier layer; 201-First well layer; 202-Second well layer; 301-First confinement layer; 302-Second confinement layer; 501-First barrier vertical layer; 502-Second barrier vertical layer; 503-Third barrier vertical layer; 601-First barrier gradient layer; 602-Second barrier gradient layer; 603-Third barrier gradient layer; 604-Fourth barrier gradient layer. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Reference Figure 1 The structure-band diagram of the active layer of a traditional vertical-cavity surface-emitting laser (VCSEL) is shown. The active layer of a traditional VCSEL includes a confinement layer (3), an energy barrier layer (1), and a well layer (2), where both the energy barrier layer and the well layer are vertical structures. (Refer to...) Figure 2 In traditional vertical-cavity surface-emitting lasers (VCSELs), N-type electrons and P-type holes in the barrier layer cannot easily cross it; they can only cross it after a well layer is filled. The barrier layer in traditional VCSELs is typically made of AlGaAs (aluminum gallium arsenide), where Al atoms comprise 35% and Ga atoms comprise 65%. (0.35) Ga (0.65) The band gap of As is 1.859 eV (electron volts); the energy barrier layer is made of AlGaAs, in which Al atoms account for 20% and Ga atoms account for 80%. (0.2) Ga (0.8) The bandgap of As is 1.672 eV; the well layer material is InGaAs (indium gallium arsenide), in which In atoms account for 10%, Ga atoms account for 90%, and In... (0.1) Ga (0.9) The band width of As is 1.279 eV.

[0032] To facilitate understanding of this embodiment, the embodiments of the present invention will be described in detail below.

[0033] Example 1:

[0034] Figure 3 This is a schematic diagram of the epitaxial structure of the active layer of the laser provided in Embodiment 1 of the present invention.

[0035] Reference Figure 3An epitaxial structure of the active layer (also known as the quantum well active region layer / active layer) of a laser is used in a vertical cavity surface-emitting laser. The epitaxial structure includes: an energy barrier layer 1, a well layer 2, and a confinement layer 3; wherein, the first confinement layer 301 and the second confinement layer 302 are located on both sides of the active layer 4; the first confinement layer 301 is connected to the first energy barrier layer 101; the second confinement layer 302 is connected to the second energy barrier layer 102; between the first energy barrier layer 101 and the second energy barrier layer 102, there is a periodic structure consisting of a first well layer 201 and a third energy barrier layer 103 from bottom to top, and the second well layer 202; the periodic structure includes at least one periodic unit, and each periodic unit includes alternating stacked first well layers 201 and third energy barrier layers 103; the energy barrier layer 1 includes an energy barrier vertical layer 5 and an energy barrier gradient layer 6.

[0036] Here, the number of periodic structures can be set according to the actual situation. The energy barrier layer is connected to the well layer. From bottom to top, the first energy barrier layer is connected to the first well layer in the periodic structure, the third energy barrier layer is connected to the second well layer, and the second well layer is connected to the second energy barrier layer.

[0037] The confinement layer is used to prevent excessive carriers from continuously crossing the well layer and the energy barrier layer; the carriers include electrons and holes.

[0038] The energy barrier vertical layer is used to prevent carriers from directly entering the next well layer from one well layer.

[0039] Energy barrier gradient layers are used to reduce the thickness of the energy barrier layer so that the volume of the well layer can be relatively increased to accommodate more carriers.

[0040] Here, refer to Figure 4 The energy barrier gradient layer and the energy barrier vertical layer together constitute the energy barrier layer. The energy barrier gradient layer can reduce the thickness of the upper part of the energy barrier layer, thereby assisting the carrier to cross or tunnel through the energy barrier vertical layer and transfer from one well layer to the next well layer, thus increasing the volume of the well layer.

[0041] Wells are used to allow electrons and holes to combine and become photons.

[0042] Here, electrons and holes recombine to become photons, which make the laser emit light.

[0043] In one embodiment, reference is made to Figure 5 The first barrier layer 101 includes a first barrier vertical layer 501 and a first barrier gradient layer 601 connected from bottom to top; the second barrier layer 102 includes a second barrier gradient layer 602 and a second barrier vertical layer 502 connected from bottom to top; the third barrier layer 103 includes a third barrier gradient layer 603, a third barrier vertical layer 503 and a fourth barrier gradient layer 604 connected from bottom to top.

[0044] In one embodiment, reference is made to Figure 6The energy barrier gradient layer uses linearly gradient AlGaAs, in which the proportion of Al atoms is 0-20% and the proportion of Ga atoms is 1-80%.

[0045] Here, in the energy barrier gradient layer, the Al is linearly gradient. (0.0to 0.2) Ga (1.0to 0.8) The band width of As ranges from 1.442 eV to 1.672 eV.

[0046] The confinement layer is made of AlGaAs, in which Al atoms account for 35% and Ga atoms account for 65%.

[0047] Here, the confinement layer material Al (0.35) Ga (0.65) The band width of As is 1.859 eV.

[0048] The energy barrier vertical layer uses AlGaAs as the material, with Al atoms accounting for 20% and Ga atoms accounting for 80% in the confinement layer.

[0049] Here, Al in the vertical energy barrier layer (0.2) Ga (0.8) The band width of As is 1.672 eV.

[0050] The well layer uses InGaAs material, in which In atoms account for 10% and Ga atoms account for 90%.

[0051] Here, well material In (0.1) Ga (0.9) The band width of As is 1.279 eV.

[0052] In one embodiment, the barrier gradient layer is a linear gradient structure, epitaxially grown according to a preset temperature, preset pressure, and preset crystal growth rate; wherein the preset temperature and preset pressure are controlled by a metal-organic chemical vapor deposition apparatus; and the preset crystal growth rate is controlled by a mass flow controller.

[0053] Here, the preset temperature, preset pressure, and preset crystal growth rate are preset based on the characteristics of linearly gradient AlGaAs.

[0054] The growth rate of the extensional growth of the energy barrier gradient layer varies linearly, and the growth rate is equal to the slope of the energy barrier gradient layer.

[0055] Specifically, refer to Figure 7The active layer band structure is as follows: when the energy barrier gradient layer grows epitaxially from the energy barrier vertical layer to the well layer, the temperature and pressure are gradually adjusted using MOCVD (Metal-Organic Chemical Vapor Deposition) according to preset temperature and pressure, and the crystal growth rate is gradually adjusted using MFC (Mass Flow Controller) according to preset crystal growth rate, so that the Al atom content in the linearly gradient AlGaAs gradually changes from 0 to 20% and the Ga atom content gradually changes from 1 to 80%. When the energy barrier gradient layer grows epitaxially from the well layer to the energy barrier vertical layer, the temperature and pressure are gradually adjusted using MOCVD (Metal-Organic Chemical Vapor Deposition) according to preset temperature and pressure, and the crystal growth rate is gradually adjusted using MFC (Mass Flow Controller) according to preset crystal growth rate, so that the Al atom content in the linearly gradient AlGaAs gradually changes from 20% to 0 and the Ga atom content gradually changes from 80% to 1.

[0056] Taking the third energy barrier layer between two well layers as an example, the third and fourth energy barrier graded layers within the third energy barrier layer can be divided into several equal parts. By changing the temperature, pressure, and crystal growth rate of each segment of the energy barrier graded layer, the epitaxial growth rate of that segment can be controlled, thereby changing the slope of the energy barrier graded layer. With the epitaxial growth rate maintaining a linear change, the more segments the layer is divided into, the closer it will be to the ideal linear graded layer.

[0057] This invention provides an epitaxial structure for the active layer of a laser, applied to a vertical-cavity surface-emitting laser. The epitaxial structure includes a barrier layer, a well layer, and a confinement layer. A first confinement layer and a second confinement layer are located on opposite sides of the active layer. The first confinement layer is connected to the first barrier layer. The second confinement layer is connected to the second barrier layer. Between the first and second barrier layers, a periodic structure consisting of a first well layer and a third barrier layer, arranged from bottom to top, is formed by the second well layer. The periodic structure includes at least one periodic unit, and each periodic unit includes alternating first well layers and third barrier layers. The barrier layer includes a barrier vertical layer and a barrier gradient layer. In this approach, by setting the barrier layer as a barrier vertical layer and a barrier gradient layer with a gradient structure, the thickness of the barrier layer is reduced, thereby increasing the volume of the well layer and improving the carrier recombination probability in the well layer. This, in turn, reduces the possibility of electron leakage, thereby improving the internal quantum efficiency of the laser.

[0058] Example 2:

[0059] An epitaxial structure for the active layer of a vertical cavity surface-emitting laser includes: an energy barrier layer, a well layer, and a confinement layer; wherein, a first confinement layer and a second confinement layer are located on opposite sides of the active layer; the first confinement layer is connected to the first energy barrier layer; the second confinement layer is connected to the second energy barrier layer; between the first energy barrier layer and the second energy barrier layer, there is a periodic structure consisting of a first well layer and a third energy barrier layer from bottom to top, and a second well layer; the periodic structure includes at least one periodic unit, and each periodic unit includes alternating first well layers and third energy barrier layers.

[0060] Figure 8 The structure-band diagrams are for two other active layer epitaxial structures provided in Embodiment 2 of the present invention.

[0061] Reference Figure 8 To meet the specific requirements of a vertical cavity surface-emitting laser, the epitaxial structure of the energy barrier layer can be adjusted by regulating the temperature, pressure, and crystal growth rate within the energy barrier layer.

[0062] In one embodiment, the active layer epitaxial structure can be, from bottom to top, a confinement layer, a barrier vertical layer, a barrier gradient layer, a well layer, a barrier gradient layer, a well layer, a barrier gradient layer, a well layer, a barrier gradient layer, a well layer, a barrier vertical layer, and a confinement layer.

[0063] In one embodiment, the active layer epitaxial structure can be, from bottom to top, a confinement layer, a barrier vertical layer, a well layer, a barrier vertical layer, a barrier gradient layer, a well layer, a barrier gradient layer, a barrier vertical layer, a well layer, a barrier vertical layer, and a confinement layer.

[0064] This invention provides an epitaxial structure for the active layer of a laser, applied to a vertical-cavity surface-emitting laser (VCSEL). The epitaxial structure includes a barrier layer, a well layer, and a confinement layer. A first confinement layer and a second confinement layer are located on opposite sides of the active layer. The first confinement layer is connected to the first barrier layer. The second confinement layer is connected to the second barrier layer. Between the first and second barrier layers, from bottom to top, there is a periodic structure consisting of a first well layer and a third barrier layer, and a second well layer. The periodic structure includes at least one periodic unit, and each periodic unit includes alternating first well layers and third barrier layers. The barrier layer includes a barrier vertical layer and a barrier gradient layer. In this approach, the epitaxial growth structure of the barrier vertical layer and the barrier gradient layer in the barrier layer can be adjusted according to the performance requirements of the VCSEL, thereby improving the internal quantum efficiency of the laser.

[0065] Example 3:

[0066] Figure 9 This is a flowchart of the growth method for the active layer epitaxial structure of a laser provided in Embodiment 3 of the present invention.

[0067] Reference Figure 9A growth method for the active layer epitaxial structure of a vertical-cavity surface-emitting laser, including:

[0068] Step S1: Form a first energy barrier layer on the first confinement layer;

[0069] Step S2: Form the first well layer on the first energy barrier layer;

[0070] Step S3: Form a third energy barrier layer on the first well layer;

[0071] Step S4: Repeat steps S2 to S3 until a periodic structure of a preset number of periodic units is formed, and form a second well layer on the third energy barrier layer that is finally formed.

[0072] Step S5: A second energy barrier layer is formed on the second well layer;

[0073] Step S6: A second confinement layer is formed on the second barrier layer.

[0074] This invention provides a method for growing an epitaxial structure of the active layer of a laser, applied to a vertical-cavity surface-emitting laser. The epitaxial structure includes a barrier layer, a well layer, and a confinement layer. A first confinement layer and a second confinement layer are located on opposite sides of the active layer. The first confinement layer is connected to the first barrier layer. The second confinement layer is connected to the second barrier layer. Between the first and second barrier layers, a periodic structure consisting of a first well layer and a third barrier layer, arranged from bottom to top, is formed by the second well layer. The periodic structure includes at least one periodic unit, and each periodic unit includes alternating first well layers and third barrier layers. The barrier layer includes a barrier vertical layer and a barrier gradient layer. In this method, by setting the barrier layer as a barrier vertical layer and a barrier gradient layer with a gradient structure, the thickness of the barrier layer is reduced, thereby increasing the volume of the well layer and improving the carrier recombination probability in the well layer. This reduces the possibility of electron leakage, thereby improving the internal quantum efficiency of the laser.

[0075] Example 4:

[0076] Figure 10 This is a schematic diagram of the laser structure provided in Embodiment 4 of the present invention.

[0077] Reference Figure 10The structure of the laser includes: the epitaxial structure of the active layer of the laser, and also includes a p-type electrode 7 (p-contact), an n-type electrode 8 (n-contact), a substrate 9 (Substrate), an n-type Bragg reflector layer 10 (n-DBR), a p-type Bragg reflector layer 11 (p-DBR), and an oxide layer 12 (Oxide aperture). The substrate 9, the n-type Bragg reflector layer 10, the active region 4, the oxide layer 12, and the p-type Bragg reflector layer 11 are connected sequentially from bottom to top. The p-type electrode 7 is placed on the p-type Bragg reflector layer 11, and the n-type electrode 8 is placed on the substrate 9.

[0078] This invention provides a laser whose active layer epitaxial structure includes: an energy barrier layer, a well layer, and a confinement layer; wherein, a first confinement layer and a second confinement layer are located on opposite sides of the active layer; the first confinement layer is connected to the first energy barrier layer; the second confinement layer is connected to the second energy barrier layer; between the first energy barrier layer and the second energy barrier layer, there is a periodic structure consisting of a first well layer and a third energy barrier layer from bottom to top, and a second well layer; the periodic structure includes at least one periodic unit, and each periodic unit includes alternating first well layers and third energy barrier layers; the energy barrier layer includes an energy barrier vertical layer and an energy barrier gradient layer. In this laser, the carrier recombination probability of the active layer is high, the possibility of electron leakage is low, and the internal quantum efficiency of the laser is high.

[0079] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and apparatus described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0080] Furthermore, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0081] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0082] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0083] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An epitaxial structure for the active layer of a laser, characterized in that, An epitaxial structure for use in vertical-cavity surface-emitting lasers includes: an energy barrier layer, a well layer, and a confinement layer; wherein, a first confinement layer and a second confinement layer are located on opposite sides of the active layer; the first confinement layer is connected to the first energy barrier layer; the second confinement layer is connected to the second energy barrier layer; between the first energy barrier layer and the second energy barrier layer, there is a periodic structure consisting of a first well layer and a third energy barrier layer from bottom to top, and a second well layer; the periodic structure includes at least one periodic unit, and each periodic unit includes alternating stacked first well layers and the third energy barrier layer; the energy barrier layer includes an energy barrier vertical layer and an energy barrier gradient layer; The confinement layer is used to prevent excessive carriers from continuously crossing the well layer and the energy barrier layer; wherein the carriers include electrons and holes; The energy barrier vertical layer is used to prevent the carrier from directly entering the next well layer from one well layer; The energy barrier gradient layer is used to reduce the thickness of the energy barrier layer so as to relatively increase the volume of the well layer to accommodate more carriers; The well layer is used to allow the electrons and holes to merge, so that the electrons and holes recombine into photons; The first barrier layer includes a first barrier vertical layer and a first barrier gradient layer connected from bottom to top; the second barrier layer includes a second barrier gradient layer and a second barrier vertical layer connected from bottom to top; the third barrier layer includes a third barrier gradient layer, a third barrier vertical layer and a fourth barrier gradient layer connected from bottom to top. The energy barrier gradient layer is made of linearly gradient AlGaAs, wherein the proportion of Al atoms in the linearly gradient AlGaAs is 0~20% and the proportion of Ga atoms is 1~80%.

2. The epitaxial structure according to claim 1, characterized in that, The energy barrier gradient layer is a linear gradient structure, which is epitaxially grown according to a preset temperature, preset pressure and preset crystal growth rate; wherein, the preset temperature and preset pressure are controlled by a metal-organic chemical vapor deposition device; and the preset crystal growth rate is controlled by a mass flow controller.

3. The epitaxial structure according to claim 2, characterized in that, The growth rate of the epitaxial growth of the energy barrier gradient layer varies linearly, and the growth rate is the slope of the energy barrier gradient layer.

4. The epitaxial structure according to claim 1, characterized in that, The confinement layer is made of AlGaAs, wherein Al atoms account for 35% and Ga atoms account for 65% of the confinement layer.

5. The epitaxial structure according to claim 1, characterized in that, The energy barrier vertical layer is made of AlGaAs, wherein the Al atoms account for 20% and the Ga atoms account for 80% of the confinement layer.

6. The epitaxial structure according to claim 1, characterized in that, The well layer is made of InGaAs material, wherein the proportion of In atoms in the confinement layer is 10% and the proportion of Ga atoms in the confinement layer is 90%.

7. A method for growing an epitaxial structure of an active layer in a laser, applied to a vertical-cavity surface-emitting laser, characterized in that, include: Step S1: Form a first energy barrier layer on the first confinement layer; Step S2: Form a first well layer on the first energy barrier layer; Step S3: Form a third energy barrier layer on the first well layer; Step S4: Repeat steps S2 to S3 until a periodic structure of a preset number of periodic units is formed, and form a second well layer on the third energy barrier layer that is finally formed. Step S5: Form a second energy barrier layer on the second well layer; Step S6: Form a second confinement layer on the second energy barrier layer; The first energy barrier layer includes a first energy barrier vertical layer and a first energy barrier gradient layer connected from bottom to top; the second energy barrier layer includes a second energy barrier gradient layer and a second energy barrier vertical layer connected from bottom to top; and the third energy barrier layer includes a third energy barrier gradient layer, a third energy barrier vertical layer and a fourth energy barrier gradient layer connected from bottom to top. The energy barrier gradient layer is made of linearly gradient AlGaAs, wherein the proportion of Al atoms in the linearly gradient AlGaAs is 0~20% and the proportion of Ga atoms is 1~80%.

8. A laser, characterized in that, include: The epitaxial structure of the active laser layer according to claim 1 further includes a p-type electrode, an n-type electrode, a substrate, an n-type Bragg reflector layer, a p-type Bragg reflector layer, and an oxide layer, wherein the substrate, the n-type Bragg reflector layer, the active layer, and the p-type Bragg reflector layer are connected sequentially from bottom to top, the p-type electrode is placed on the p-type Bragg reflector layer, and the n-type electrode is placed on the substrate.

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