Laser and method for manufacturing the same

Abstract

The present application relates to a laser and a method for preparing the same. The laser comprises a substrate, a first reflective layer, a first lattice transition layer, a light-emitting active layer and a second reflective layer which are stacked in sequence, wherein the lattice constant of the first lattice transition layer is greater than the lattice constant of the first reflective layer and less than the lattice constant of the light-emitting active layer, so that the first lattice transition layer is lattice matched with the first reflective layer and the light-emitting active layer respectively, thereby fundamentally solving the problem that a high-performance laser cannot be prepared due to lattice mismatch between the first reflective layer and the light-emitting active layer.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a laser and a method for preparing the same. Background Art

[0002] Vertical cavity surface emitting lasers (VCSELs) have the advantage of low cost compared to edge emitting lasers in the field of data communications, and in consumer facial recognition applications, VCSELs can penetrate OLED screens to achieve the function of face recognition under the screen. Currently, VCSELs with a wavelength of light in the near-infrared band above 1300nm can be realized by growing GaInNAs quantum well active regions, growing InAs / GaAs quantum dot active regions, or growing InP quantum well active regions. The specific problem of InP-based VCSELs is that the binary distributed Bragg reflector (DBR) of the InP system has poor heat dissipation performance and a small refractive index difference, so the InP base and DBR are prone to lattice mismatch, which affects the performance and life of the laser. Summary of the invention

[0003] Based on this, it is necessary to provide a laser with superior performance and durability to address the above technical problems.

[0004] A laser comprises a substrate, a first reflection layer, a first lattice transition layer, a light-emitting active layer and a second reflection layer stacked in sequence, wherein:

[0005] The lattice constant of the first lattice transition layer is greater than the lattice constant of the first reflective layer, and is smaller than the lattice constant of the light-emitting active layer.

[0006] In one embodiment, the first lattice transition layer comprises:

[0007] A superlattice structure layer, comprising a plurality of buffer structures arranged in a periodic manner, wherein the buffer structure comprises a plurality of material layers of different components, and / or,

[0008] Composition gradient layer, including In x GaAs y P gradient layer and / or In x AlAs y P gradient layer, in which the ranges of x and y are 0 to 1 respectively, and x gradually increases and y gradually decreases in the stacking direction.

[0009] In one embodiment, the material layer includes a GaAs system material layer and an InP system material layer; and / or the period of the buffer structure is 20 to 60, and the thickness of the buffer structure in each period is 2nm to 10nm.

[0010] In one embodiment, the laser further comprises:

[0011] The second lattice transition layer is disposed between the light-emitting active layer and the second reflective layer, wherein the lattice constant of the second lattice transition layer is greater than the lattice constant of the second reflective layer and is smaller than the lattice constant of the light-emitting active layer.

[0012] In one embodiment, the composition of the second lattice transition layer is the same as that of the first lattice transition layer, and the structure of the second lattice transition layer is symmetrical to that of the first lattice transition layer with respect to the light-emitting active layer.

[0013] In one embodiment, the laser further comprises:

[0014] The oxidation restriction layer is arranged between the second lattice transition layer and the second reflective layer, and the oxidation restriction layer forms a through hole in parallel to the stacking direction.

[0015] In one embodiment, the laser further comprises:

[0016] An ohmic contact layer is provided on the upper surface of the second reflective layer, and the ohmic contact layer comprises:

[0017] A third lattice transition layer, disposed on the upper surface of the second reflective layer;

[0018] The heavily doped p-type GaAs layer is arranged on the upper surface of the third lattice transition layer. The third lattice transition layer is an AlGaAs gradient layer, in which the Al component varies in the range of 0.1 to 0.9 and gradually decreases in the stacking direction.

[0019] A laser preparation method is used to prepare the above-mentioned laser, and the preparation method comprises:

[0020] providing a substrate;

[0021] A first reflective layer, a first lattice transition layer, a light-emitting active layer and a second reflective layer are sequentially stacked and grown on the substrate, wherein the lattice constant of the first lattice transition layer is greater than that of the first reflective layer and smaller than that of the light-emitting active layer.

[0022] In one embodiment, growing the first lattice transition layer comprises:

[0023] A plurality of buffer structures are periodically grown within a temperature range of 450° C. to 550° C., wherein the buffer structures include a plurality of material layers of different components, and / or,

[0024] In was grown in the temperature range of 580°C to 450°C x GaAs y P gradient layer and / or In x AlAsy P gradient layer.

[0025] In one embodiment, growing the second reflective layer comprises:

[0026] Growing a second lattice transition layer on the upper surface of the light-emitting active layer;

[0027] Growing the second reflective layer on the upper surface of the second lattice transition layer; the growing the second reflective layer on the upper surface of the second lattice transition layer further comprises:

[0028] Growing an oxidation restriction layer on the upper surface of the second lattice transition layer, wherein the oxidation restriction layer forms a through hole in parallel to the stacking direction;

[0029] The second reflective layer is grown on the upper surface of the oxidized restriction layer.

[0030] In one embodiment, the preparation method further comprises:

[0031] An ohmic contact layer is grown on the upper surface of the second reflective layer.

[0032] The laser of the above embodiment includes a substrate, a first reflective layer, a first lattice transition layer, a light-emitting active layer and a second reflective layer stacked in sequence, wherein the lattice constant of the first lattice transition layer is greater than the lattice constant of the first reflective layer and smaller than the lattice constant of the light-emitting active layer, so that the first lattice transition layer is lattice matched with the first reflective layer and the light-emitting active layer respectively, thereby fundamentally solving the problem that a high-performance laser cannot be prepared due to lattice mismatch between the first reflective layer and the light-emitting active layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 is a schematic diagram of the structure of a laser in an embodiment of the present application;

[0035] Figure 2 is a schematic structural diagram of a laser in another embodiment of the present application;

[0036] Figure 3 is a schematic structural diagram of a laser in another embodiment of the present application;

[0037] Figure 4 is a schematic structural diagram of a laser in another embodiment of the present application;

[0038] Figure 5 It is a schematic diagram of the process of preparing a laser in one embodiment of the present application.

[0039] Component number description:

[0040] Substrate: 100; first reflective layer: 101; first lattice transition layer: 102; light-emitting active layer: 103; second reflective layer: 104; second lattice transition layer: 105; oxidation restriction layer: 106; ohmic contact layer: 107 DETAILED DESCRIPTION

[0041] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0043] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0044] In the accompanying drawings, the sizes of layers and regions may be exaggerated for clarity. It is understood that when a layer or element is referred to as being "on" another layer or substrate, the layer or element may be directly on the other layer or substrate, or there may be intervening layers. In addition, it is also understood that when a layer is referred to as being "between" two layers, the layer may be the only layer between the two layers, or there may be one or more intervening layers. In addition, the same reference numerals always represent the same elements.

[0045] In the following embodiments, when a layer, region, or element is "connected", it can be interpreted that the layer, region, or element is not only directly connected but also connected through other constituent elements placed therebetween. For example, when a layer, region, element, etc. is described as being connected or electrically connected, the layer, region, element, etc. can be connected or electrically connected not only directly or directly, but also through another layer, region, element, etc. placed therebetween.

[0046] Hereinafter, although terms such as "first", "second", etc. may be used to describe various components, these components are not necessarily limited to the above terms. The above terms are only used to distinguish one component from another. It will also be understood that expressions used in the singular include plural expressions unless the expression in the singular has an obviously different meaning in the context.

[0047] When a statement such as "at least one (of)..." is located after a list of elements, it modifies the entire list of elements rather than the individual elements in the list. The term "and / or" as used herein includes any and all combinations of one or more related listed items. As used in the application documents, the term "and / or" includes any and all combinations of one or more related listed items. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0048] Figure 1 FIG. 1 is a schematic diagram of the structure of a laser according to an embodiment of the present invention. Figure 1 As shown, the laser includes a substrate 100, a first reflective layer 101, a first lattice transition layer 102, a light-emitting active layer 103 and a second reflective layer 104 stacked in sequence, wherein the lattice constant of the first lattice transition layer 102 is greater than the lattice constant of the first reflective layer 101, and less than the lattice constant of the light-emitting active layer 103.

[0049] The substrate 100 may be a GaAs material, which has low cost and mature later integration process. The first reflective layer 101 may be a binary distributed Bragg reflector (DBR), which is a periodic structure composed of two materials with different refractive indices arranged alternately, and the optical thickness of each layer of material is 1 / 4 of the central reflection wavelength, so as to form a reflective mirror with a certain reflectivity to provide sufficient gain for the outgoing light, wherein the first reflective layer 101 may be a GaAs-based system material, and the first reflective layer 101 prepared from a GaAs-based system material has high reflectivity and high heat dissipation. The light-emitting active layer 103 may be a quantum well active region composed of InP system materials, which can realize the emission of near-infrared light with a wavelength in the range of 1300nm to 1700nm for application in specific usage scenarios. However, there is a lattice mismatch problem between the first reflective layer 101 of GaAs-based system materials and the light-emitting active layer 103 of InP system materials. Growing the light-emitting active layer 103 directly on the first reflective layer 101 will make the quality of the light-emitting active layer 103 poor, thereby affecting the performance of the laser.

[0050] In the traditional method, the InP-based laser can be made by first growing a GaAs-based DBR, and then forming a complete laser structure with the InP quantum well active region by bonding. However, the bonding method is likely to introduce series resistance because the bonding occurs between the active region and the DBR, and the bonding method will also reduce the device yield and yield. A first lattice transition layer 102 with a lattice constant between the first reflective layer 101 and the light-emitting active layer 103 is arranged between the first reflective layer 101 and the light-emitting active layer 103, so that the first lattice transition layer 102 is lattice-matched with the first reflective layer 101 and the light-emitting active layer 103, respectively, thereby fundamentally solving the problem that a high-performance laser cannot be prepared due to lattice mismatch between the first reflective layer 101 and the light-emitting active layer 103.

[0051] The laser of the embodiment of the present invention includes a substrate 100, a first reflective layer 101, a first lattice transition layer 102, a light-emitting active layer 103 and a second reflective layer 104 stacked in sequence, wherein the lattice constant of the first lattice transition layer 102 is greater than the lattice constant of the first reflective layer 101, and less than the lattice constant of the light-emitting active layer 103, so that the first lattice transition layer 102 is lattice matched with the first reflective layer 101 and the light-emitting active layer 103, respectively, thereby fundamentally solving the problem that a high-performance laser cannot be prepared due to lattice mismatch between the first reflective layer 101 and the light-emitting active layer 103.

[0052] In one embodiment, the first lattice transition layer 102 includes a superlattice structure layer and / or a composition gradient layer, wherein the superlattice structure layer includes a plurality of buffer structures arranged periodically, and the buffer structure includes multiple material layers of different components; the composition gradient layer includes In x GaAsy P gradient layer and / or In x AlAs y P gradient layer, in which the ranges of x and y are 0 to 1 respectively, and x gradually increases and y gradually decreases in the stacking direction.

[0053] It can be understood that the first lattice transition layer 102 may only include a superlattice structure layer, wherein the superlattice structure layer includes a plurality of buffer structures, and the plurality of buffer structures are periodically stacked between the first reflective layer 101 and the light-emitting active layer 103, and each buffer structure includes a plurality of material layers of different components. In one embodiment, the buffer structure may include two material layers, for example, represented by material layer A and material layer B, and material layer A and material layer B constitute a periodic buffer structure, and then the plurality of periodically arranged buffer structures form a superlattice structure layer of ABAB... structure in the stacking direction.

[0054] The first lattice transition layer 102 may also include only a composition gradient layer, and the composition gradient layer may only include In x GaAs y P gradient layer, or only In x AlAs y P gradient layer, or In x GaAs y P gradient layer and In x AlAs y A combination of P gradient layers, wherein the subscript x of the component In and the subscript As in the same gradient layer vary from 0 to 1, respectively, and x gradually increases and y gradually decreases in the stacking direction, wherein the stacking direction is the direction from the substrate 100 to the light-emitting active layer 103.

[0055] It can be understood that a gradient layer of a compound is a combination of multiple compound layers formed when the subscript of a component in the compound takes different values, wherein the subscript value of the component in each compound layer increases or decreases in the stacking direction. x GaAs y For example, the P gradient layer can be In 0.1 GaAs 0.9 P material layer, In 0.3 GaAs 0.7 P material layer and In 0.4 GaAs 0.5 The P material layers are stacked in a stacking direction.

[0056] In addition, the first lattice transition layer 102 may also include a superlattice structure layer and a composition gradient layer at the same time, and the superlattice structure layer and the composition gradient layer are stacked in the stacking direction.

[0057] In one embodiment, the material layer may include a GaAs system material layer and an InP system material layer.

[0058] It can be understood that the two material layers in the buffer structure can be a GaAs system material layer and an InP system material layer respectively. Specifically, the GaAs system material may include one of InxGaAs (x value is 0.2~0.4) material and InxAlAs (x value is 0.2~0.4) material; the InP system material may include one of InxGaAsyP (x value is 0.1~0.2, y value is 0.1~0.2) material, InxAlAsyP (x value is 0~0.1, y value is 0.1~0.2) material, and InP material, that is, one of the material layers in the buffer structure is one of InxGaAs (x value is 0.2~0.4) material and InxAlAs (x value is 0.2~0.4) material, and the other material layer is one of InxGaAsyP (x value is 0.1~0.2, y value is 0.1~0.2) material, InxAlAsyP (x value is 0~0.1, y value is 0.1~0.2) material and InP material.

[0059] In one embodiment, the period of the buffer structure is 20 to 60, and the thickness of each period of the buffer structure is 2 nm to 10 nm.

[0060] In one embodiment, the laser further includes a second lattice transition layer 105, which is disposed between the light-emitting active layer 103 and the second reflective layer 104, wherein the lattice constant of the second lattice transition layer 105 is greater than the lattice constant of the second reflective layer 104, and less than the lattice constant of the light-emitting active layer 103. Figure 2 shown.

[0061] Specifically, the second reflective layer 104 can be a GaAs-based material. The second reflective layer 104 made of GaAs-based material has high reflectivity and high heat dissipation. However, there is a lattice mismatch problem between the second reflective layer 104 and the light-emitting active layer 103 made of InP-based material. The second reflective layer 104 is poor in quality if the second reflective layer 104 is directly grown on the light-emitting active layer 103, thereby affecting the performance of the laser. The bonding method introduces series resistance and reduces the yield and yield of the laser. In this embodiment, a second lattice transition layer 105 with a lattice constant between the second reflective layer 104 and the light-emitting active layer 103 is provided, so that the second lattice transition layer 105 is lattice-matched with the second reflective layer 104 and the light-emitting active layer 103, respectively, thereby fundamentally solving the problem that a high-performance laser cannot be prepared due to the lattice mismatch between the second reflective layer 104 and the light-emitting active layer 103.

[0062] In one embodiment, the composition of the second lattice transition layer 105 is the same as that of the first lattice transition layer 102 , and the structure of the second lattice transition layer 105 is symmetrical to that of the first lattice transition layer 102 with respect to the light emitting active layer 103 .

[0063] It can be understood that the composition and structure of the second lattice transition layer 105 are the same as those of the first lattice transition layer 102, so the role it plays between the second reflective layer 104 and the light-emitting active layer 103 is exactly the same as the role played by the first lattice transition layer 102 between the first reflective layer 101 and the light-emitting active layer 103.

[0064] In one embodiment, the laser further includes an oxide confinement layer 106, such as Figure 3 As shown, the oxidation restriction layer 106 is disposed between the second lattice transition layer 105 and the second reflective layer 104, and the oxidation restriction layer 106 can form a through hole parallel to the stacking direction, so as to realize the vertical end face emission of the emitted light. The material of the oxidation restriction layer 106 can be a compound with a high Al component such as AlAs, InAlxAs or GaAlxAs, the value of x is 0.9 to 0.98, and the growth thickness is 10nm to 50nm.

[0065] It can be understood that, compared with introducing complex structures such as an InP buried tunnel junction to achieve vertical end-face emission of light, the method of directly setting the oxidation restriction layer 106 between the second lattice transition layer 105 and the second reflective layer 104 in this embodiment is simpler.

[0066] In one embodiment, the first reflective layer 101 and the second reflective layer 104 are both periodic structures formed by alternating layers of two material layers with different refractive indices, wherein in each periodic structure of the first reflective layer 101 and the second reflective layer 104, the material layer with a larger refractive index is close to the light-emitting active layer 103, and the material layer with a smaller refractive index is far away from the light-emitting active layer 103.

[0067] The first reflective layer 101 can be an n-type doped GaAs-based material, the number of periods can be 25 to 45, the two material layers in each period can be any combination of GaAs, AlGaAs, and AlAs, and the Al component in AlGaAs is 0.1 to 0.9. The n-type dopant is Si, and the doping concentration is 2×10 18 cm -3 ~6×10 18 cm -3 , the growth temperature is 580℃~620℃.

[0068] The second reflective layer 104 can be a p-type doped GaAs-based material with a period number of 15 to 30. The two material layers in each period are any combination of GaAs, AlGaAs, and AlAs. The Al component in AlGaAs is 0.1 to 0.9. The p-type dopant is Be or CBr4 with a doping concentration of 2×10 18 cm -3 ~6×10 18 cm -3 , the growth temperature is 580℃~620℃.

[0069] In one embodiment, the laser further includes an ohmic contact layer 107, which is disposed on the upper surface of the second reflective layer 104. Figure 4 shown.

[0070] An electrode of the laser can be disposed on the upper surface of the second reflective layer 104 , and an ohmic contact layer 107 is disposed between the electrode and the second reflective layer 104 to reduce the contact resistance between the electrode and the second reflective layer 104 .

[0071] In one embodiment, the ohmic contact layer 107 may include a third lattice transition layer and a heavily doped p-type GaAs layer, wherein the third lattice transition layer is disposed on the upper surface of the second reflective layer 104; and the heavily doped p-type GaAs layer is disposed on the upper surface of the third lattice transition layer.

[0072] It can be understood that the ohmic contact layer 107 composed of the third lattice transition layer and the heavily doped p-type GaAs layer can reduce the contact resistance between the electrode and the second reflective layer 104, wherein the heavily doped p-type GaAs layer can be used as a cap layer to protect the third lattice transition layer from being oxidized, and the lattice constant of the third lattice transition layer is between the second reflective layer 104 and the heavily doped p-type GaAs layer, which is used to solve the lattice mismatch problem between the second reflective layer 104 and the heavily doped p-type GaAs layer. In this way, through the combination of the third lattice transition layer and the heavily doped p-type GaAs layer, the performance of the finally formed ohmic contact layer 107 is stable, which is conducive to improving the current input of the electrode. Among them, the GaAs doping concentration of the heavily doped p-type GaAs layer is 2×10 19 cm -3 ~6×10 19 cm -3 .

[0073] In one embodiment, the third lattice transition layer is an AlGaAs graded layer, in which the Al component varies in the range of 0.1 to 0.9 and gradually decreases in the stacking direction.

[0074] It can be understood that the AlGaAs with a gradient Al component has a gradient lattice constant in the stacking direction, so that it can play the role of lattice transition between the second reflective layer 104 and the second reflective layer 104. The AlGaAs gradient layer can be obtained by growing the Al component from 0.9 to 0.1 at one time, or by growing the Al component from 0.9 to 0.1 layer by layer for multiple times, for example, first grow an AlGaAs layer with an Al component of 0.9, then grow an AlGaAs layer with an Al component of 0.4, and then grow an AlGaAs layer with an Al component of 0.1, so as to achieve a transition in lattice constant. The thickness of the AlGaAs gradient layer is 20nm to 60nm, and the p-doping concentration is 1×10 19 cm -3 ~4×10 19 cm -3 , the doping source is Be or CBr4.

[0075] In one embodiment, the upper and lower surfaces of the light-emitting active layer 103 are provided with light confinement layers, respectively. The thickness of the light confinement layer is 100 nm to 300 nm. It can be understood that the light confinement layers on the upper and lower surfaces of the light-emitting active layer 103 can confine the light field to a smaller area near the light-emitting active layer 103, thereby providing sufficient gain for the laser to achieve lower threshold lasing.

[0076] The embodiment of the present invention further provides a method for preparing a laser, which is used to prepare the laser described in any of the above embodiments. The preparation method includes steps S110 to S120. Figure 5 shown.

[0077] Step S110 , providing a substrate 100 .

[0078] The substrate 100 may be made of GaAs material.

[0079] Step S120 , a first reflective layer 101 , a first lattice transition layer 102 , a light-emitting active layer 103 and a second reflective layer 104 are sequentially stacked and grown on the substrate 100 , wherein the lattice constant of the first lattice transition layer 102 is greater than the lattice constant of the first reflective layer 101 , and less than the lattice constant of the light-emitting active layer 103 .

[0080] The first reflective layer 101 can be an n-type doped GaAs-based material, the number of periods can be 25 to 45, the two material layers in each period can be any combination of GaAs, AlGaAs, and AlAs, and the Al component in AlGaAs is 0.1 to 0.9. The n-type dopant is Si, and the doping concentration is 2×10 18 cm -3 ~6×10 18 cm -3 , the growth temperature is 580~620℃.

[0081] The light-emitting active layer 103 can be a quantum well of InP / InxGaAsyP (x is 0.5-0.8, y is 0.3-0.6), the number of quantum well periods is 2-6 periods, the thickness of each period is 2nm-10nm, and the growth temperature is 450-550°C.

[0082] The second reflective layer 104 can be a p-type doped GaAs-based material with a period number of 15 to 30. The two material layers in each period are any combination of GaAs, AlGaAs, and AlAs. The Al component in AlGaAs is 0.1 to 0.9. The p-type dopant is Be or CBr4 with a doping concentration of 2×10 18 cm -3 ~6×10 18 cm -3 , the growth temperature is 580~620℃.

[0083] In one embodiment, growing the first lattice transition layer 102 includes step S111 and / or step S112 .

[0084] Step S111 , periodically growing a plurality of buffer structures within a temperature range of 450° C. to 550° C., wherein the buffer structures include a plurality of material layers of different components.

[0085] Step S112, growing In at a temperature range of 580°C to 450°C x GaAs y P gradient layer and / or In x AlAs y P gradient layer.

[0086] It can be understood that the first lattice transition layer 102 may only include a superlattice structure layer, wherein the superlattice structure layer includes a plurality of buffer structures, and the plurality of buffer structures are periodically stacked between the first reflective layer 101 and the light-emitting active layer 103, and each buffer structure includes a plurality of material layers of different components. In one embodiment, the buffer structure may include two material layers, for example, represented by material layer A and material layer B, and material layer A and material layer B constitute a periodic buffer structure, and then the plurality of periodically arranged buffer structures form a superlattice structure layer of ABAB... structure in the stacking direction.

[0087] The first lattice transition layer 102 may also include only a composition gradient layer, and the composition gradient layer may only include In x GaAs y P gradient layer, or only In x AlAs y P gradient layer, or In x GaAs y P gradient layer and Inx AlAs y A combination of P gradient layers, wherein the subscripts x of the component In and the subscripts of the component As in the same gradient layer vary from 0 to 1, respectively, and x gradually increases and y gradually decreases in the stacking direction, wherein the stacking direction is the direction from the substrate 100 to the light-emitting active layer 103. The growth thickness of the composition gradient layer is 0.5 to 1 μm, the growth temperature range is 450° C. to 580° C., and the growth temperature gradually decreases in the stacking direction.

[0088] It can be understood that a gradient layer of a compound is a combination of multiple compound layers formed when the subscript of a component in the compound takes different values, wherein the subscript value of the component in each compound layer increases or decreases in the stacking direction. x GaAs y For example, the P gradient layer can be In 0.1 GaAs 0.9 P material layer, In 0.3 GaAs 0.7 P material layer and In 0.4 GaAs 0.5 The P material layers are stacked in a stacking direction.

[0089] In addition, the first lattice transition layer 102 may also include a superlattice structure layer and a composition gradient layer at the same time, and the superlattice structure layer and the composition gradient layer are stacked in the stacking direction.

[0090] Specifically, the buffer structure may include a GaAs system material layer and an InP system material layer.

[0091] It can be understood that the two material layers in the buffer structure can be a GaAs system material layer and an InP system material layer respectively. Specifically, the GaAs system material may include one of InxGaAs (x value is 0.2~0.4) material and InxAlAs (x value is 0.2~0.4) material; the InP system material may include one of InxGaAsyP (x value is 0.1~0.2, y value is 0.1~0.2) material, InxAlAsyP (x value is 0~0.1, y value is 0.1~0.2) material, and InP material, that is, one of the material layers in the buffer structure is one of InxGaAs (x value is 0.2~0.4) material and InxAlAs (x value is 0.2~0.4) material, and the other material layer is one of InxGaAsyP (x value is 0.1~0.2, y value is 0.1~0.2) material, InxAlAsyP (x value is 0~0.1, y value is 0.1~0.2) material and InP material.

[0092] In one embodiment, the step of growing the second reflective layer 104 further includes: growing a second lattice transition layer 105 on the upper surface of the light-emitting active layer 103 ; and growing the second reflective layer 104 on the upper surface of the second lattice transition layer 105 .

[0093] The components of the second lattice transition layer 105 are the same as those of the first lattice transition layer 102 , and the structure of the second lattice transition layer 105 and the structure of the first lattice transition layer 102 are symmetrical about the light-emitting active layer 103 .

[0094] It can be understood that the composition and structure of the second lattice transition layer 105 are the same as those of the first lattice transition layer 102, and therefore its preparation method is exactly the same as the preparation method of the first lattice transition layer 102. The role played by the second lattice transition layer 105 between the second reflective layer 104 and the light-emitting active layer 103 is exactly the same as the role played by the first lattice transition layer 102 between the first reflective layer 101 and the light-emitting active layer 103.

[0095] In one embodiment, growing the second reflective layer 104 on the upper surface of the second lattice transition layer 105 further includes: growing an oxidation restriction layer 106 on the upper surface of the second lattice transition layer 105, wherein the oxidation restriction layer 106 can form a through hole parallel to the stacking direction; and growing the second reflective layer 104 on the upper surface of the oxidation restriction layer 106.

[0096] It can be understood that, compared with introducing complex structures such as an InP buried tunnel junction to achieve vertical end-face emission of light, the method of directly setting the oxidation restriction layer 106 between the second lattice transition layer 105 and the second reflective layer 104 in this embodiment is simpler.

[0097] The material of the oxidation restriction layer 106 may be a compound with a high Al component such as AlAs, InAlxAs or GaAlxAs, the value of x is 0.9-0.98, the growth thickness is 10nm-50nm, and the growth temperature is 550-620°C.

[0098] In one embodiment, the preparation method further includes growing an ohmic contact layer 107 on the upper surface of the second reflective layer 104 .

[0099] An electrode of the laser can be disposed on the upper surface of the second reflective layer 104 , and an ohmic contact layer 107 is disposed between the electrode and the second reflective layer 104 to reduce the contact resistance between the electrode and the second reflective layer 104 .

[0100] In one embodiment, the ohmic contact layer 107 may include a third lattice transition layer and a heavily doped p-type GaAs layer, wherein the third lattice transition layer is grown on the upper surface of the second reflective layer 104; and the heavily doped p-type GaAs layer is grown on the upper surface of the third lattice transition layer.

[0101] The third lattice transition layer is an AlGaAs graded layer, in which the Al component varies from 0.1 to 0.9 and gradually decreases in the stacking direction; the growth temperature range is 580℃ to 620℃ and gradually decreases in the stacking direction. The GaAs doping concentration of the heavily doped p-type GaAs layer is 2 to 6×10 19 cm -3 The growth temperature is 560~600℃ and the growth thickness is 50~100nm.

[0102] In one embodiment, growing the light emitting active layer 103 includes: growing a first light confinement layer on the upper surface of the first lattice transition layer 102 ; growing the light emitting active layer 103 on the upper surface of the first light confinement layer; and growing a second light confinement layer on the upper surface of the light emitting active layer 103 .

[0103] The thickness of the light confinement layer may be 100 nm to 300 nm. It can be understood that the two light confinement layers can confine the light field to a smaller area near the light-emitting active layer 103, thereby providing sufficient gain for the laser to achieve lower threshold lasing.

[0104] It should be understood that, although the steps in the flowchart of the accompanying drawings are displayed in sequence as indicated by the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the accompanying drawings may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a portion of the steps or stages in other steps.

[0105] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0106] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A laser, characterized in that: The invention comprises a substrate, a first reflection layer, a first lattice transition layer, a light-emitting active layer, a second reflection layer and an ohmic contact layer which are stacked in sequence, wherein: The lattice constant of the first lattice transition layer is greater than the lattice constant of the first reflective layer, and is smaller than the lattice constant of the light-emitting active layer; The ohmic contact layer is arranged on the upper surface of the second reflective layer, and the ohmic contact layer includes a third lattice transition layer and a heavily doped p-type GaAs layer, and the third lattice transition layer is arranged on the upper surface of the second reflective layer; the heavily doped p-type GaAs layer is arranged on the upper surface of the third lattice transition layer, and the third lattice transition layer is an AlGaAs gradient layer, in which the Al component varies in the range of 0.1 to 0.9 and gradually decreases in the stacking direction.

2. The laser according to claim 1, characterized in that The first lattice transition layer comprises: A superlattice structure layer, comprising a plurality of buffer structures arranged in a periodic manner, wherein the buffer structure comprises a plurality of material layers of different components, and / or, Composition gradient layer, including In x GaAs y P gradient layer and / or In x AlAs y P gradient layer, in which the ranges of x and y are 0 to 1 respectively, and x gradually increases and y gradually decreases in the stacking direction.

3. The laser according to claim 2, characterized in that The material layer includes a GaAs system material layer and an InP system material layer; and / or the period of the buffer structure is 20 to 60, and the thickness of the buffer structure in each period is 2nm to 10nm.

4. The laser according to claim 1 or 2, characterized in that: The laser also includes: The second lattice transition layer is disposed between the light-emitting active layer and the second reflective layer, wherein the lattice constant of the second lattice transition layer is greater than the lattice constant of the second reflective layer and is smaller than the lattice constant of the light-emitting active layer.

5. The laser according to claim 4, characterized in that The component of the second lattice transition layer is the same as that of the first lattice transition layer, and the structure of the second lattice transition layer is symmetrical to that of the first lattice transition layer with respect to the light-emitting active layer.

6. The laser according to claim 4, characterized in that The laser also includes: The oxidation restriction layer is arranged between the second lattice transition layer and the second reflective layer, and the oxidation restriction layer forms a through hole in parallel to the stacking direction.

7. A method for preparing a laser, characterized in that: Used to prepare the laser according to any one of claims 1 to 6, the preparation method comprising: providing a substrate; A first reflective layer, a first lattice transition layer, a light-emitting active layer, a second reflective layer and an ohmic contact layer are sequentially stacked and grown on the substrate, wherein the lattice constant of the first lattice transition layer is greater than the lattice constant of the first reflective layer and is smaller than the lattice constant of the light-emitting active layer; the ohmic contact layer is arranged on the upper surface of the second reflective layer, the ohmic contact layer comprises a third lattice transition layer and a heavily doped p-type GaAs layer, the third lattice transition layer is arranged on the upper surface of the second reflective layer; the heavily doped p-type GaAs layer is arranged on the upper surface of the third lattice transition layer, the third lattice transition layer is an AlGaAs gradient layer, wherein the Al component varies in the range of 0.1 to 0.9 and gradually decreases in the stacking direction.

8. The laser preparation method according to claim 7, characterized in that: The growing of the first lattice transition layer comprises: A plurality of buffer structures are periodically grown within a temperature range of 450° C. to 550° C., wherein the buffer structures include a plurality of material layers of different components, and / or, In was grown in the temperature range of 580°C to 450°C x GaAs y P gradient layer and / or In x AlAs y P gradient layer.

9. The laser manufacturing method according to claim 7, characterized in that: The growing the second reflective layer comprises: Growing a second lattice transition layer on the upper surface of the light-emitting active layer; Growing the second reflective layer on the upper surface of the second lattice transition layer; the growing the second reflective layer on the upper surface of the second lattice transition layer further comprises: Growing an oxidation restriction layer on the upper surface of the second lattice transition layer, wherein the oxidation restriction layer forms a through hole in parallel to the stacking direction; The second reflective layer is grown on the upper surface of the oxidized restriction layer.

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