Vertical cavity surface emitting laser and preparation method thereof

Abstract

The invention provides a vertical cavity surface emitting laser and a preparation method thereof, and relates to the technical field of semiconductor lasers. The vertical cavity surface emitting laser comprises a substrate, an N-type DBR layer, an active layer, a P-type DBR layer and a light emitting layer, the N-type DBR layer, the active layer, the P-type DBR layer and the light emitting layer are sequentially arranged on the substrate in a stacked mode in the preset direction, the P-type DBR layer comprises multiple pairs of first dielectric layers and second dielectric layers which are arranged in a stacked mode in the preset direction, oxidation layers are arranged between part of the first dielectric layers and part of the second dielectric layers, oxidation through holes are formed in the oxidation layers, and the light emitting layer is arranged between the first dielectric layers and the second dielectric layers. The oxidation through holes are filled with the first dielectric layer or the second dielectric layer, the number of the oxidation layers is multiple, and the positions of the oxidation through holes in the multiple oxidation layers correspond to each other. The vertical-cavity surface-emitting laser has good light-emitting quality, the bit error rate of a device where the vertical-cavity surface-emitting laser is located can be greatly reduced, and the performance of the device is improved.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor lasers, and in particular to a vertical cavity surface emitting laser and a method for preparing the same. Background Art

[0002] Vertical-Cavity Surface-Emitting Laser (VCSEL) is widely used in data centers, short-distance optical interconnection, lidar and other fields due to its advantages such as high conversion efficiency, low threshold current, low power consumption and easy integration.

[0003] When VCSEL is used in signal transmission devices, its light output quality is very important and will have a significant impact on the bit error rate of the signal transmission device. As the market's requirements for the reliability of signal transmission devices become higher and higher, the existing VCSEL light output quality can no longer meet the high reliability requirements of signal transmission devices. Summary of the invention

[0004] The purpose of the present application is to provide a vertical cavity surface emitting laser and a preparation method thereof, which have good light output quality, can significantly reduce the bit error rate of the device and improve the performance of the device, in view of the deficiencies in the above-mentioned prior art.

[0005] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0006] In one aspect of an embodiment of the present application, a vertical cavity surface emitting laser is provided, comprising: a substrate, an N-type DBR layer, an active layer, a P-type DBR layer and a light output layer stacked in sequence on the substrate along a preset direction, the P-type DBR layer comprising a plurality of pairs of first dielectric layers and second dielectric layers stacked in a preset direction, an oxide layer is provided between part of the first dielectric layer and the second dielectric layer, an oxide through hole is provided on the oxide layer, the oxide through hole is filled with the first dielectric layer or the second dielectric layer, the number of the oxide layers is multiple layers, and the positions of the oxide through holes on the multiple oxide layers correspond.

[0007] Optionally, a thinning hole is provided on a surface of the light emitting layer facing away from the substrate, the depth of the thinning hole is less than the thickness of the light emitting layer, and the thinning hole corresponds to the position of the oxidation through hole.

[0008] Optionally, among two adjacent oxidation through holes, the aperture of the oxidation through hole closer to the substrate is smaller than or equal to the aperture of the other oxidation through hole.

[0009] Optionally, the materials of the first dielectric layer and the second dielectric layer are both aluminum gallium arsenide, and the content of aluminum in the first dielectric layer and the second dielectric layer is 95% to 98%.

[0010] Optionally, a metal connection layer is provided between the P-type DBR layer and the light output layer, and the metal connection layer completely covers the surface of the P-type DBR layer.

[0011] Another aspect of an embodiment of the present application provides a method for preparing a vertical cavity surface emitting laser, comprising: providing a substrate, and sequentially forming an N-type DBR layer and an active layer on the substrate along a preset direction; alternately forming a plurality of pairs of first dielectric layers and second dielectric layers on the active layer along a preset direction, and forming an oxide layer between part of the first dielectric layer and the second dielectric layer, wherein oxide through holes are provided on the oxide layer, and the positions of the oxide through holes on the multiple oxide layers correspond; and forming a light output layer on the topmost second dielectric layer.

[0012] Optionally, after forming a light emitting layer on the top second dielectric layer, the method further includes: forming a thinning hole on the surface of the light emitting layer, wherein the depth of the thinning hole is less than the thickness of the light emitting layer, and the thinning hole corresponds to the position of the oxidation through hole.

[0013] Optionally, multiple pairs of first dielectric layers and second dielectric layers are alternately formed on the active layer along a preset direction, and an oxide layer is formed between some of the first dielectric layers and the second dielectric layers, wherein oxide through holes are provided on the oxide layer, and the positions of the oxide through holes on the multi-layer oxide layer correspond to each other, including: forming at least one pair of first dielectric layers and second dielectric layers on the active layer along a preset direction; oxidizing the surface of the second dielectric layer to form an oxide layer on the surface of the second dielectric layer, and forming oxide through holes on the oxide layer; forming at least one pair of first dielectric layers and second dielectric layers on the oxide layer along a preset direction; oxidizing the surface of the second dielectric layer of the uppermost layer to form an oxide layer on the surface of the second dielectric layer, and forming oxide through holes on the oxide layer; repeating the steps of preparing the first dielectric layer, the second dielectric layer and the oxide layer until all oxide layers are prepared, wherein the positions of the oxide through holes on the multi-layer oxide layer correspond to each other; forming at least one pair of first dielectric layers and second dielectric layers on the uppermost oxide layer along a preset direction.

[0014] Optionally, along a preset direction, the aluminum content in the plurality of first dielectric layers gradually decreases, and the aluminum content in the plurality of second dielectric layers gradually decreases.

[0015] Optionally, forming the light emitting layer on the uppermost second dielectric layer includes: forming a metal connection layer on the uppermost second dielectric layer, and forming the light emitting layer on the metal connection layer.

[0016] The beneficial effects of this application include:

[0017] The present application provides a vertical cavity surface emitting laser, comprising: a substrate, an N-type DBR layer, an active layer, a P-type DBR layer and a light emitting layer stacked in sequence on the substrate along a preset direction, the P-type DBR layer comprising a plurality of pairs of first dielectric layers and second dielectric layers stacked along a preset direction, an oxide layer is provided between part of the first dielectric layer and the second dielectric layer, an oxide through hole is provided on the oxide layer, the oxide through hole is filled by the first dielectric layer or the second dielectric layer, the number of oxide layers is multiple layers, and the positions of the oxide through holes on the multiple oxide layers correspond. The vertical cavity surface emitting laser is provided with multiple oxide layers in the P-type DBR layer, the oxide layer can reflect the laser, and the laser emitted in the active layer is emitted outward through the area where the oxide through hole is located, so the range of the oxide through hole limits the range of laser emission. In addition, the oxide layer also has an insulating effect, which can limit the flow path of the current entering the P-type DBR layer, so that the current flows through the oxide through hole. In the multi-layer oxide layer, the oxide layers close to the active layer (usually 1-2 layers) mainly play the role of optical limitation and current limitation, and the remaining oxide layers mainly play the role of correcting the current path and controlling the escaped light. The multi-layer oxide layers cooperate with each other to gradually correct the laser light shape, thereby realizing the shape control of the laser spot and improving the light quality. The good light quality of the vertical cavity surface emitting laser can greatly reduce the bit error rate of the device in which it is located and improve the performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of the structure of a vertical cavity surface emitting laser provided in an embodiment of the present application;

[0020] Figure 2 A schematic diagram of the structure of a P-type DBR layer and an oxide layer in a vertical cavity surface emitting laser provided in an embodiment of the present application;

[0021] Figure 3 One of the flow charts of the method for preparing a vertical cavity surface emitting laser provided in an embodiment of the present application;

[0022] Figure 4 Flow chart 2 of the method for preparing a vertical cavity surface emitting laser provided in an embodiment of the present application;

[0023] Figure 5 The third flowchart of the method for preparing a vertical cavity surface emitting laser provided in an embodiment of the present application.

[0024] Icon: 10-vertical cavity surface emitting laser; 11-substrate; 12-N-type DBR layer; 13-active layer; 14-P-type DBR layer; 141-first dielectric layer; 142-second dielectric layer; 15-light output layer; 151-thinning hole; 16-oxide layer; 161-oxide through hole; 17-metal connection layer. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. It should be noted that, in the absence of conflict, the various features in the embodiments of the present application can be combined with each other, and the combined embodiments are still within the scope of protection of the present application.

[0027] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0028] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0029] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0030] In one aspect of the embodiment of the present application, please refer to Figure 1 , a vertical cavity surface emitting laser 10 is provided, comprising: a substrate 11, an N-type DBR layer 12, an active layer 13, a P-type DBR layer 14 and a light emitting layer 15 which are sequentially stacked on the substrate 11 along a preset direction. The preset direction is perpendicular to the surface of the substrate 11, and the laser formed by the cooperation of the N-type DBR layer 12, the active layer 13 and the P-type DBR layer 14 is emitted through the light emitting layer 15.

[0031] Please refer to Figure 2 The P-type DBR layer 14 includes a plurality of pairs of first dielectric layers 141 and second dielectric layers 142 stacked in a preset direction. The first dielectric layers 141 and the second dielectric layers 142 have different band gaps, which can allow electrons and holes to recombine and emit photons. An oxide layer 16 is provided between part of the first dielectric layer 141 and the second dielectric layer 142. The oxide layer 16 is provided with an oxide through hole 161. The oxide through hole 161 is filled with the first dielectric layer 141 or the second dielectric layer 142. The oxide layer 16 has multiple layers, and the positions of the oxide through holes 161 on the multiple oxide layers 16 correspond.

[0032] The oxide layer 16 can reflect the laser light, and the laser light emitted from the active layer 13 is emitted outward through the area where the oxide through hole 161 is located. Therefore, the range of the oxide through hole 161 limits the range of laser emission. In addition, the oxide layer 16 also has an insulating effect, which can limit the flow path of the current entering the P-type DBR layer 14, so that the current flows through the oxide through hole 161. In the multi-layer oxide layer 16, the oxide layers 16 (generally 1-2 layers) close to the active layer 13 mainly play the role of optical limitation and current limitation, and the remaining oxide layers mainly play the role of correcting the current path and controlling the escaped light. The multi-layer oxide layers 16 cooperate with each other to gradually correct the laser light shape, thereby realizing the control of the shape of the laser spot and improving the light output quality. The good light output quality of the vertical cavity surface emitting laser 10 can greatly reduce the bit error rate of the device in which it is located and improve the performance of the device.

[0033] Optionally, a thinning hole 151 is provided on the surface of the light emitting layer 15 facing away from the substrate 11 , the depth of the thinning hole 151 is less than the thickness of the light emitting layer 15 , and the position of the thinning hole 151 corresponds to that of the oxidation through hole 161 .

[0034] The thinning hole 151 is a blind hole and does not penetrate the light output layer 15. The thinning hole 151 thins the thickness of the light output layer 15 in the area where it is located, thereby forming an anti-reflection area and a reflection area on the light output layer 15. Among them, the area where the thinning hole 151 is located is the anti-reflection area, and the other areas on the light output layer 15 are the reflection areas. Part of the laser emitted by the P-type DBR layer 14 is reflected by the reflection area, and the other part is emitted through the anti-reflection area. The setting of the thinning hole 151 realizes the second optical control, strengthens the modal control and limitation, and further improves the light output quality.

[0035] Optionally, among two adjacent oxidation through holes 161 , the aperture of the oxidation through hole 161 closer to the substrate 11 is smaller than or equal to the aperture of the other oxidation through hole 161 .

[0036] That is to say, in Figure 1 In the perspective of the oxidation through hole 161, the aperture of the oxidation through hole 161 located below is smaller than or equal to the aperture of the oxidation through hole 161 located above it. In this way, the shape of the laser spot can be better controlled. Generally speaking, the aperture of the oxidation through hole 161 gradually increases along the preset direction.

[0037] Optionally, the materials of the first dielectric layer 141 and the second dielectric layer 142 are both aluminum gallium arsenide, and the content of aluminum in the first dielectric layer 141 and the second dielectric layer 142 is 95% to 98%.

[0038] By adjusting the aluminum content in the first dielectric layer 141 and the second dielectric layer 142 and appropriately increasing the thickness of the P-type DBR layer 14, a plurality of oxide layers 16 with oxide through holes 161 are formed in the P-type DBR layer 14, which can convert constructive interference into destructive interference, causing abnormal superposition of optical light output, thereby better controlling the shape of the laser spot.

[0039] Optionally, a metal connection layer 17 is provided between the P-type DBR layer 14 and the light output layer 15 , and the metal connection layer 17 is used to connect to an external circuit.

[0040] The metal connection layer 17 is used to connect to an external circuit and introduce current into the P-type DBR layer 14 . At the same time, it can also protect the P-type DBR layer 14 .

[0041] Please refer to Figure 3 This embodiment also provides a method for preparing a vertical cavity surface emitting laser, comprising:

[0042] S100: providing a substrate, and sequentially forming an N-type DBR layer and an active layer on the substrate along a preset direction.

[0043] S200: alternately forming a plurality of pairs of first dielectric layers and second dielectric layers on the active layer along a preset direction, and forming an oxide layer between a portion of the first dielectric layer and the second dielectric layer, wherein the oxide layer is provided with oxide through holes, and the positions of the oxide through holes on the multiple oxide layers correspond.

[0044] S300: forming a light emitting layer on the uppermost second dielectric layer.

[0045] Please refer to Figure 1 and Figure 2 The N-type DBR layer 12, the active layer 13, the first dielectric layer 141, the second dielectric layer 142 and the light-emitting layer 15 can all be formed by material deposition. The oxide layer 16 can be formed by material deposition or by oxidizing the film layer below it, which is not limited in this embodiment.

[0046] The vertical cavity surface emitting laser 10 prepared by the above-mentioned method for preparing a vertical cavity surface emitting laser has good light output quality, can significantly reduce the bit error rate of the device in which it is located, and improve the performance of the device.

[0047] Optionally, after forming the light emitting layer on the uppermost second dielectric layer, the method further comprises:

[0048] S400: forming a thinning hole on the surface of the light emitting layer, wherein the depth of the thinning hole is less than the thickness of the light emitting layer, and the thinning hole corresponds to the position of the oxidation through hole.

[0049] At this time, the light-emitting layer 15 of the prepared vertical cavity surface emitting laser 10 has an anti-reflection area and a reflection area, wherein the area where the thinning hole 151 is located is the anti-reflection area, and the other areas on the light-emitting layer 15 are the reflection areas. A part of the laser emitted by the P-type DBR layer 14 is reflected by the reflection area, and the other part is emitted through the anti-reflection area. The setting of the thinning hole 151 realizes the second optical control, strengthens the mode control and limitation, and further improves the light output quality of the vertical cavity surface emitting laser 10.

[0050] Optionally, see Figure 4 , a plurality of pairs of first dielectric layers and second dielectric layers are alternately formed on the active layer along a preset direction, and an oxide layer is formed between part of the first dielectric layer and the second dielectric layer, wherein the oxide layer is provided with an oxide through hole, and the positions of the oxide through holes on the multi-layer oxide layer correspond to:

[0051] S210: forming at least one pair of a first dielectric layer and a second dielectric layer on the active layer along a preset direction.

[0052] S220: performing oxidation treatment on the surface of the second dielectric layer to form an oxide layer on the surface of the second dielectric layer, and forming an oxide through hole on the oxide layer.

[0053] S230: forming at least one pair of a first dielectric layer and a second dielectric layer on the oxide layer along a preset direction.

[0054] S240: performing oxidation treatment on the surface of the uppermost second dielectric layer to form an oxide layer on the surface of the second dielectric layer, and forming an oxide through hole on the oxide layer.

[0055] S250: Repeat the steps of preparing the first dielectric layer, the second dielectric layer and the oxide layer until all oxide layers are prepared, wherein the positions of the oxide through holes on the multiple oxide layers correspond to each other.

[0056] S260: forming at least one pair of a first dielectric layer and a second dielectric layer on the uppermost oxide layer along a preset direction.

[0057] Please refer to Figure 2 In the above process, the P-type DBR layer 14 is formed in multiple steps, and multiple layers of oxide layers 16 are formed in between. Specifically, at least one pair of first dielectric layers 141 and second dielectric layers 142 are first formed on the active layer 13 along a preset direction, and then the surface of the second dielectric layer 142 of the uppermost layer is oxidized, so that part of the second dielectric layer 142 is oxidized into an oxide layer 16. After the first oxide layer 16 is obtained, an oxidized through hole 161 is formed on the oxide layer 16, and the oxidized through hole 161 can be obtained by etching. Afterwards, at least one pair of first dielectric layers 141 and second dielectric layers 142 are formed on the first oxide layer along a preset direction, and then the surface of the second dielectric layer 142 of the uppermost layer is oxidized, so that part of the second dielectric layer 142 is oxidized into an oxide layer 16. After the second oxide layer 16 is obtained, an oxidized through hole 161 is formed on the oxide layer 16. The above steps are repeated until all the oxide layers 16 are prepared. Finally, at least one pair of first dielectric layer 141 and second dielectric layer 142 are formed along a preset direction on the top oxide layer 16, so that the P-type DBR layer 14 and the multi-layer oxide layer 16 are formed. The oxide layer 16 is obtained by oxidizing the surface of the second dielectric layer 142, which is simple and convenient to operate.

[0058] Optionally, along a preset direction, the aluminum content in the plurality of first dielectric layers 141 gradually decreases, and the aluminum content in the plurality of second dielectric layers 142 gradually decreases.

[0059] The aluminum content in the first dielectric layer 141 and the second dielectric layer 142 in the P-type DBR layer 14 gradually decreases, so that the oxidation depths in different second dielectric layers 142 are different, thereby forming oxide layers 16 of different thicknesses, thereby generating destructive interference and filtering out noise.

[0060] Optionally, see Figure 5 , forming a light emitting layer on the uppermost second dielectric layer comprises:

[0061] S310: forming a metal connection layer on the uppermost second dielectric layer, and forming a light emitting layer on the metal connection layer.

[0062] The metal connection layer 17 is used to connect to an external circuit and introduce current into the P-type DBR layer 14 . At the same time, it can also protect the P-type DBR layer 14 .

[0063] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A vertical cavity surface emitting laser, characterized in that: include: A substrate, an N-type DBR layer, an active layer, a P-type DBR layer and a light-emitting layer stacked in sequence on the substrate along a preset direction, the P-type DBR layer includes a plurality of pairs of first dielectric layers and second dielectric layers stacked along the preset direction, an oxide layer is arranged between part of the first dielectric layer and the second dielectric layer, an oxide through hole is arranged on the oxide layer, the oxide through hole is filled with the first dielectric layer or the second dielectric layer, the number of the oxide layers is multiple, and the positions of the oxide through holes on the multiple oxide layers correspond.

2. The vertical cavity surface emitting laser according to claim 1, characterized in that: A thinning hole is provided on the surface of the light emitting layer facing away from the substrate, the bottom of the thinning hole is located in the light emitting layer, and the thinning hole corresponds to the position of the oxidation through hole.

3. The vertical cavity surface emitting laser according to claim 1, characterized in that: Of the two adjacent oxidation through holes, the aperture of the oxidation through hole closer to the substrate is smaller than or equal to the aperture of the other oxidation through hole.

4. The vertical cavity surface emitting laser according to claim 1, characterized in that: The materials of the first dielectric layer and the second dielectric layer are both aluminum gallium arsenide, and the content of aluminum in the first dielectric layer and the second dielectric layer is 95% to 98%.

5. The vertical cavity surface emitting laser according to any one of claims 1 to 4, characterized in that: A metal connection layer is provided between the P-type DBR layer and the light output layer, and the metal connection layer is used to be connected to an external circuit.

6. A method for preparing a vertical cavity surface emitting laser, characterized in that: include: Providing a substrate, and sequentially forming an N-type DBR layer and an active layer on the substrate along a preset direction; Alternately forming a plurality of pairs of first dielectric layers and second dielectric layers on the active layer along the preset direction, and forming an oxide layer between a portion of the first dielectric layer and the second dielectric layer, wherein the oxide layer is provided with oxide through holes, and the oxide through holes on the plurality of oxide layers are located in corresponding positions; A light emitting layer is formed on the uppermost second dielectric layer.

7. The method for preparing a vertical cavity surface emitting laser according to claim 6, characterized in that: After forming the light emitting layer on the second dielectric layer on the top, the method further includes: A thinning hole is formed on the surface of the light emitting layer, wherein the depth of the thinning hole is less than the thickness of the light emitting layer, and the thinning hole corresponds to the position of the oxidation through hole.

8. The method for preparing a vertical cavity surface emitting laser according to claim 6, characterized in that: A plurality of pairs of first dielectric layers and second dielectric layers are alternately formed on the active layer along the preset direction, and an oxide layer is formed between a portion of the first dielectric layer and the second dielectric layer, wherein the oxide layer is provided with oxide through holes, and the positions of the oxide through holes on the multiple oxide layers correspond to: Forming at least one pair of first dielectric layer and second dielectric layer on the active layer along the preset direction; performing oxidation treatment on the surface of the second dielectric layer to form an oxide layer on the surface of the second dielectric layer, and forming an oxide through hole on the oxide layer; forming at least one pair of the first dielectric layer and the second dielectric layer on the oxide layer along the preset direction; Performing oxidation treatment on the surface of the second dielectric layer as the uppermost layer to form the oxide layer on the surface of the second dielectric layer, and forming an oxide through hole on the oxide layer; Repeating the steps of preparing the first dielectric layer, the second dielectric layer and the oxide layer until all the oxide layers are prepared, wherein the oxide through holes on the multiple oxide layers are located in a corresponding position; At least one pair of the first dielectric layer and the second dielectric layer is formed on the uppermost oxide layer along the preset direction.

9. The method for preparing a vertical cavity surface emitting laser according to claim 8, characterized in that: Along the preset direction, the aluminum content in the first dielectric layers gradually decreases, and the aluminum content in the second dielectric layers gradually decreases.

10. The method for preparing a vertical cavity surface emitting laser according to claim 6, characterized in that: The step of forming a light emitting layer on the second dielectric layer of the uppermost layer comprises: A metal connection layer is formed on the second dielectric layer which is the uppermost layer, and a light extraction layer is formed on the metal connection layer.

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