阅读说明：本技术 垂直腔面发射激光器及电子设备 (Vertical cavity surface emitting laser and electronic apparatus ) 是由 张驰 兰洋 沈健 于 2021-03-15 设计创作，主要内容包括：本申请提供一种垂直腔面发射激光器和电子设备,垂直腔面发射激光器包括：衬底,以及在衬底上依次层叠设置的第二反射器、第二隔离层、有源层、第一隔离层以及第一反射器,第二反射器和第一反射器之间限定出谐振腔；第一反射器包括相互层叠设置的第一光栅层和第一透明导电层,第一光栅层的材料的折射率大于第一透明导电层的材料的折射率；第一反射器上具有供激光射出的出光区域；第一透明导电层和第一光栅层均至少覆盖出光区域。本申请能够减小器件的串联电阻,减少器件的产热,提高器件的热稳定性和可靠性。(The application provides a vertical cavity surface emitting laser and electronic equipment, vertical cavity surface emitting laser includes: the semiconductor device comprises a substrate, and a second reflector, a second isolation layer, an active layer, a first isolation layer and a first reflector which are sequentially stacked on the substrate, wherein a resonant cavity is defined between the second reflector and the first reflector; the first reflector comprises a first grating layer and a first transparent conducting layer which are mutually stacked, and the refractive index of the material of the first grating layer is larger than that of the material of the first transparent conducting layer; the first reflector is provided with a light emitting area for emitting laser; the first transparent conducting layer and the first grating layer at least cover the light emitting area. This application can reduce the series resistance of device, reduces the heat production of device, improves the thermal stability and the reliability of device.)

1. A vertical cavity surface emitting laser, comprising: the semiconductor device comprises a substrate, and a second reflector, a second isolation layer, an active layer, a first isolation layer and a first reflector which are sequentially stacked on the substrate, wherein a resonant cavity is defined between the second reflector and the first reflector; the first reflector comprises a first grating layer and a first transparent conducting layer which are mutually stacked, and the refractive index of the material of the first grating layer is larger than that of the material of the first transparent conducting layer; the first reflector is provided with a light emitting area for emitting laser, and the light emitting area corresponds to the arrangement position of the active layer;

the first transparent conducting layer and the first grating layer at least cover the light emitting area.

2. A vertical cavity surface emitting laser according to claim 1,

the orthographic projection of the active layer on the first transparent conductive layer is located in the arrangement area of the first transparent conductive layer, the orthographic projection of the active layer on the first grating layer is located in the arrangement area of the first grating layer, and the area, which is opposite to the active layer, on the first reflector is the light emitting area.

3. A vertical cavity surface emitting laser according to claim 1,

the orthographic projection of the first transparent conducting layer on the active layer is located in the arrangement area of the active layer, and the area, which is opposite to the first transparent conducting layer, on the first reflector is the light emitting area.

4. A vertical cavity surface emitting laser according to claim 1,

the first transparent conductive layer is in direct contact with the first isolation layer so that current in the first transparent conductive layer is injected into the active layer through the first isolation layer.

5. A vertical cavity surface emitting laser according to any one of claims 1 through 4,

the first transparent conducting layer is arranged on one surface, deviating from the second reflector, of the first isolation layer, and the first grating layer is arranged on one surface, deviating from the first isolation layer, of the first transparent conducting layer.

6. A vertical cavity surface emitting laser according to claim 5,

the first transparent conductive layer is a continuous film layer.

7. A vertical cavity surface emitting laser according to claim 5,

the first reflector further comprises a protective layer, the protective layer is arranged on the first transparent conductive layer and covers the first grating layer, and the refractive index of the material of the protective layer is lower than that of the material of the first grating layer.

8. A vertical cavity surface emitting laser according to any one of claims 1 through 4,

first grating layer is located first isolation layer deviates from on the one side of second reflector, first transparent conducting layer is located first grating layer deviates from on the one side of first isolation layer.

9. A vertical cavity surface emitting laser according to claim 8,

the first grating layer comprises a plurality of grating bodies arranged at intervals, the grating bodies form grating ridges of the first grating layer, and the intervals between every two adjacent grating bodies form grating valleys of the first grating layer.

10. A vertical cavity surface emitting laser according to claim 9,

the material of the grating body in the first grating layer is the same as that of the first isolation layer.

11. A vertical cavity surface emitting laser according to claim 10,

the first transparent conducting layer is of a hollow structure so as to form a plurality of electric conductors arranged at intervals, and the electric conductors correspond to the grating bodies one to one so as to form a grating structure in the first transparent conducting layer.

12. A vertical cavity surface emitting laser according to claim 10,

the first transparent conducting layer is a continuous film layer, covers the tops of the grating bodies and covers the intervals among the grating bodies.

13. A vertical cavity surface emitting laser according to any one of claims 8 through 12,

the first reflector further comprises a protective layer, the protective layer is arranged on one side, away from the active layer, of the first transparent conductive layer, and the refractive index of the material of the protective layer is lower than that of the material of the first grating layer.

14. A vertical cavity surface emitting laser according to claim 7 or 13,

and a first electrode part is formed at the part of the first transparent conductive layer, which is not covered by the protective layer, and the first electrode part is used for being electrically connected with an external circuit.

15. A vertical cavity surface emitting laser according to claim 7 or 13,

the refractive index of the material of the first grating layer is greater than or equal to 1.4 times of the refractive index of the material of the protective layer, and the extinction coefficient of the first grating layer is less than 0.05.

16. A vertical cavity surface emitting laser according to any one of claims 1 through 15,

the first grating layer is a sub-wavelength grating layer.

17. A vertical cavity surface emitting laser according to any one of claims 1 through 15,

the first transparent conductive layer is made of a material with the resistivity lower than 5x10^-3Non-metallic material of Ω · cm; and/or

The first transparent conductive layer has an extinction coefficient less than 0.03 to laser emitted by the vertical cavity surface emitting laser; and/or

The first transparent conductive layer has an absorptivity of less than 0.5% with respect to laser light emitted from the VCSEL.

18. A vertical cavity surface emitting laser according to any one of claims 1 through 15,

the material of the first transparent conducting layer is transparent conducting oxide.

19. A vertical cavity surface emitting laser according to any one of claims 1 through 15,

the first grating layer comprises a plurality of grating bodies arranged at intervals, and the grating bodies are long-strip-shaped; or

The first grating layer comprises a plurality of grating bodies arranged at intervals, the grating bodies are island-shaped, and the cross sections of the island-shaped grating bodies are square, circular or hexagonal.

20. A vertical cavity surface emitting laser according to claim 19,

the grating bodies are island-shaped, and the island-shaped grating bodies are arranged in an array or in a honeycomb shape.

21. A vertical cavity surface emitting laser according to any one of claims 1 through 15,

the refractive index of the material of the first grating layer is greater than or equal to 1.4 times of the refractive index of the material of the first transparent conductive layer, and the first grating layer has an extinction coefficient less than 0.1 for the laser emitted by the vertical cavity surface emitting laser.

22. A vertical cavity surface emitting laser according to any one of claims 1 through 15,

the material of the first grating layer is at least one of silicon, gallium nitride, indium phosphide, molybdenum sulfide and gallium phosphide.

23. A vertical cavity surface emitting laser according to any one of claims 1 through 15,

the reflectivity of the second reflector to the laser light emitted by the vertical cavity surface emitting laser is higher than the reflectivity of the first reflector to the laser light emitted by the vertical cavity surface emitting laser.

24. A vertical cavity surface emitting laser according to any one of claims 1 through 23,

the LED lamp further comprises a substrate and a second electrode, wherein the second reflector is stacked on the substrate, the second electrode is stacked on one surface of the substrate, which faces away from the second reflector, and the second electrode is used for being electrically connected with an external circuit.

25. A vertical cavity surface emitting laser according to any one of claims 1 through 23,

the second reflector comprises a distributed Bragg reflector.

26. A vertical cavity surface emitting laser according to claim 25,

the second reflector comprises a plurality of high-refractive-index material layers and a plurality of low-refractive-index material layers, the number of the high-refractive-index material layers is the same as that of the low-refractive-index material layers, each high-refractive-index material layer and each low-refractive-index material layer are alternately stacked, and the number of the low-refractive-index material layers in the second reflector is 20-30.

27. A vertical cavity surface emitting laser according to claim 25,

the distributed Bragg reflector further comprises a second conductive layer and a second electrode, wherein the second conductive layer is laminated between the distributed Bragg reflector and the substrate, the distributed Bragg reflector and the second electrode are laminated on the second conductive layer at intervals, and the second electrode is used for being electrically connected with an external circuit.

28. A vertical cavity surface emitting laser according to any one of claims 1 through 23,

the second reflector includes a second grating layer and a second transparent conductive layer formed on the second grating layer, a refractive index of a material of the second grating layer is greater than a refractive index of a material of the second transparent conductive layer,

the orthographic projection of the active layer on the second transparent conductive layer is located in the setting area of the second transparent conductive layer, and the orthographic projection of the active layer on the second grating layer is located in the setting area of the second grating layer.

29. A vertical cavity surface emitting laser according to claim 28,

the second transparent conductive layer is in direct contact with the second isolation layer such that current in the active layer is injected into the second transparent conductive layer through the second isolation layer.

30. A vertical cavity surface emitting laser according to claim 28 or 29,

the second transparent conducting layer is arranged on one surface, deviating from the first reflector, of the second isolation layer, and the second grating layer is arranged on one surface, deviating from the second isolation layer, of the second transparent conducting layer.

31. A vertical cavity surface emitting laser according to claim 30,

the second reflector further comprises a flat layer, and the flat layer is arranged on one surface of the second transparent conducting layer, which is far away from the first reflector, and covers the second grating layer.

32. A vertical cavity surface emitting laser according to claim 31,

the refractive index of the material of the planarization layer is lower than the refractive index of the material of the second grating layer.

33. A vertical cavity surface emitting laser according to claim 32,

the refractive index of the material of the flat layer is less than 0.7 times the refractive index of the material of the second grating layer, and the flat layer has an extinction coefficient less than 0.1 for laser light emitted in the VCSEL.

34. A vertical cavity surface emitting laser according to claim 31,

the bonding layer is arranged between the substrate and the flat layer and used for bonding the substrate and the flat layer.

35. A vertical cavity surface emitting laser according to any one of claims 1 through 33,

the cross section of the active layer is in any one of a square shape, a circular shape, a triangular shape and a hexagonal shape.

36. An electronic device comprising the vertical cavity surface emitting laser according to any one of claims 1 to 35.

Technical Field

The present application relates to the field of semiconductor laser technology, and more particularly, to a vertical cavity surface emitting laser and an electronic device.

Background

A Vertical-Cavity Surface-Emitting Laser (VCSEL) is a novel semiconductor Laser Emitting element, and has the excellent characteristics of small threshold current, low cost, low power consumption, small divergence angle, high coupling efficiency with an optical fiber, high modulation rate realization, easy mass array production and test, and the like. The VCSEL is applied to the field of optical communication firstly, and is applied to the fields of the Internet of things, 5G communication, advanced driving systems and the like on a large scale in the future.

The conventional vertical cavity surface emitting laser is generally composed of iii-v compound semiconductor materials, and referring to fig. 1, the vertical cavity surface emitting laser 80 includes: a lower Distributed Bragg Reflector 82 (DBR), an n-type spacer 83, an active region 84, a p-type spacer 85, and an upper Distributed Bragg Reflector 86 are sequentially stacked on the substrate 81. Wherein the DBR is formed by stacking a plurality of pairs of films of high and low refractive index 1/4 wavelength optical thickness. In addition, an annular upper metal electrode 87 is further disposed at the top edge of the upper dbr 86, and a lower metal electrode 89 is further disposed at a portion of the substrate 81 protruding from the package 88. Further, a current confinement layer 90 is further provided in the upper dbr 86 at a position close to the edge portion, the current confinement layer 90 is entirely in an annular structure and is located substantially directly below the upper metal electrode 87, the current confinement layer 90 may be formed with a cylindrical current flow channel K in the center portion of the upper dbr 86, the active region 84, the lower dbr 82, and the like, and the upper metal electrode 87 and the current flow channel K may be displaced from each other in the device thickness direction.

However, in the above-described vertical cavity surface emitting laser, the device current is injected into the active region through the DBR and into the current flow path defined by the annular current confinement layer, which introduces a large series resistance, increases heat generation of the device, and results in poor thermal stability and reliability of the device.

Disclosure of Invention

The application provides a vertical cavity surface emitting laser and an electronic device, the series resistance of the device is small, and the thermal stability and the reliability of the device are good.

A first aspect of the present application provides a vertical cavity surface emitting laser including: the semiconductor device comprises a substrate, and a second reflector, a second isolation layer, an active layer, a first isolation layer and a first reflector which are sequentially stacked on the substrate, wherein a resonant cavity is defined between the second reflector and the first reflector; the first reflector comprises a first grating layer and a first transparent conducting layer which are mutually stacked, and the refractive index of the material of the first grating layer is larger than that of the material of the first transparent conducting layer; the first reflector is provided with a light emitting area for emitting laser; the light emitting area corresponds to the arrangement area of the active layer, and the first transparent conductive layer and the first grating layer at least cover the light emitting area.

In a possible embodiment, an orthographic projection of the active layer on the first transparent conductive layer is located in the arrangement region of the first transparent conductive layer, and an orthographic projection of the active layer on the first grating layer is located in the arrangement region of the first grating layer, and a region, which is opposite to the active layer, on the first reflector is a light emergent region.

In a possible implementation mode, the orthographic projection of the first transparent conducting layer on the active layer is located in the arrangement area of the active layer, and the area, opposite to the first transparent conducting layer, of the first reflector is a light emergent area. In one possible embodiment, the first transparent conductive layer is in direct contact with the first isolation layer, so that the current in the first transparent conductive layer is injected into the active layer through the first isolation layer.

In a possible implementation manner, the first transparent conductive layer is disposed on a surface of the first isolation layer departing from the second reflector, and the first grating layer is disposed on a surface of the first transparent conductive layer departing from the first isolation layer.

In one possible embodiment, the first transparent conductive layer is a continuous film layer.

In a possible implementation manner, the first reflector further includes a protective layer, the protective layer is disposed on the first transparent conductive layer and covers the first grating layer, and a refractive index of a material of the protective layer is lower than a refractive index of a material of the first grating layer.

In a possible implementation manner, the first grating layer is disposed on a surface of the first isolation layer departing from the second reflector, and the first transparent conductive layer is disposed on a surface of the first grating layer departing from the first isolation layer.

The first grating layer comprises a plurality of grating bodies arranged at intervals, the grating bodies form grating ridges of the first grating layer, and the intervals between adjacent grating bodies form grating valleys of the first grating layer.

In a possible embodiment, the material of the grating body in the first grating layer is the same as the material of the first isolation layer.

In one possible embodiment, the first transparent conductive layer is a continuous film layer, and the first transparent conductive layer covers the first grating layer.

In a possible implementation manner, the first transparent conductive layer is a hollow structure to form a plurality of electric conductors arranged at intervals, and the electric conductors correspond to the grating bodies one to one, so that the grating structure is formed in the first transparent conductive layer.

In a possible embodiment, the first reflector further includes a protective layer, the protective layer is disposed on a side of the first transparent conductive layer facing away from the active layer, and a refractive index of a material of the protective layer is lower than a refractive index of a material of the first grating layer.

In one possible embodiment, the portion of the first transparent conductive layer not covered by the protective layer forms a first electrode portion for electrical connection with an external circuit.

In one possible embodiment, the refractive index of the material of the first grating layer is greater than or equal to 1.4 times the refractive index of the material of the protective layer, and the extinction coefficient of the first grating layer is less than 0.05.

In one possible embodiment, the first grating layer is a sub-wavelength grating layer.

In one possible embodiment, the first transparent conductive layer is made of a material with a resistivity lower than that of the first transparent conductive layer

5x10^-3Non-metallic material of Ω · cm; and/or the first transparent conductive layer has an extinction coefficient less than 0.03 to laser light emitted by the vertical cavity surface emitting laser; and/or first passThe absorptivity of the transparent conductive layer to laser light emitted by the vertical cavity surface emitting laser is lower than 0.5%.

In one possible embodiment, the material of the first transparent conductive layer is a transparent conductive oxide.

In one possible embodiment, the first grating layer comprises a plurality of grating bodies arranged at intervals, and the grating bodies are long strips; or the grating body is in an island shape, and the cross section of the island-shaped grating body is one of square, round and hexagon.

In a possible embodiment, when the grating bodies are island-shaped, the individual island-shaped grating bodies are arranged in an array or in a honeycomb shape.

In one possible embodiment, the refractive index of the material of the first grating layer is greater than or equal to 1.4 times the refractive index of the material of the first transparent conductive layer, and the first grating layer has an extinction coefficient less than 0.1 for laser light emitted by the vertical cavity surface emitting laser.

In one possible embodiment, the material of the first grating layer is at least one of silicon, gallium nitride, indium phosphide, molybdenum sulfide, and gallium phosphide.

In one possible embodiment, the reflectivity of the second reflector for laser light emitted by the VCSEL is higher than the reflectivity of the first reflector for laser light emitted by the VCSEL.

In one possible embodiment, the second reflector comprises a distributed bragg reflector.

In one possible embodiment, the second reflector comprises a plurality of high refractive index material layers and a plurality of low refractive index material layers, the number of the high refractive index material layers is the same as that of the low refractive index material layers, each high refractive index material layer and each low refractive index material layer are alternately laminated, and the number of the low refractive index material layers in the second reflector is 20-30.

In one possible embodiment, the distributed bragg reflector further comprises a substrate, a second conductive layer and a second electrode, wherein the second conductive layer is laminated between the distributed bragg reflector and the substrate, the distributed bragg reflector and the second electrode are laminated on the second conductive layer at intervals, and the second electrode is used for being electrically connected with an external circuit.

In one possible implementation, the second reflector includes a second grating layer and a second transparent conductive layer formed on the second grating layer, the refractive index of the material of the second grating layer is greater than the refractive index of the material of the second transparent conductive layer, and the orthographic projection of the active layer on the second transparent conductive layer is located in the arrangement area of the second transparent conductive layer; and the orthographic projection of the active layer on the second grating layer is positioned in the setting area of the second grating layer.

In one possible embodiment, the second transparent conductive layer is in direct contact with the second isolation layer, so that the current in the active layer is injected into the second transparent conductive layer through the second isolation layer; and/or the orthographic projection of the active layer on the second grating layer is positioned in the arrangement area of the second grating layer.

In a possible implementation manner, the second transparent conductive layer is disposed on a surface of the second isolation layer facing away from the first reflector, and the second grating layer is disposed on a surface of the second transparent conductive layer facing away from the second isolation layer.

In one possible embodiment, the second reflector further comprises a flat layer, which is disposed on a side of the second transparent conductive layer facing away from the first reflector and covers the second grating layer.

In one possible embodiment, the refractive index of the material of the planarization layer is lower than the refractive index of the material of the second grating layer.

In one possible embodiment, the refractive index of the material of the planar layer is less than 0.7 times the refractive index of the material of the second grating layer, and the planar layer has an extinction coefficient less than 0.1 for laser light emitted in a vertical cavity surface emitting laser.

In a possible embodiment, the device further comprises a substrate and a bonding layer, wherein the bonding layer is arranged between the substrate and the flat layer and is used for bonding the substrate and the flat layer.

In one possible embodiment, the material of the bonding layer is metal or oxide.

In one possible embodiment, the semiconductor device further includes a sealing portion surrounding the second isolation layer, the active layer, and the first isolation layer.

In one possible embodiment, the cross-sectional shape of the active layer is any one of square, circular, triangular, and hexagonal.

A second aspect of the present application provides an electronic device including the vertical cavity surface emitting laser described above.

The application relates to a vertical cavity surface emitting laser and an electronic device, wherein the vertical cavity surface emitting laser comprises: the semiconductor device comprises a substrate, and a second reflector, a second isolation layer, an active layer, a first isolation layer and a first reflector which are sequentially stacked on the substrate, wherein a resonant cavity is defined between the second reflector and the first reflector; the first reflector comprises a first grating layer and a first transparent conducting layer which are mutually stacked, and the refractive index of the material of the first grating layer is larger than that of the material of the first transparent conducting layer; the first reflector is provided with a light emitting area for emitting laser; the light emitting area corresponds to the arrangement area of the active layer, and the first transparent conductive layer and the first grating layer at least cover the light emitting area. In the above solution, the first reflector includes the first grating layer and the first transparent conductive layer, and the first transparent conductive layer and the first grating layer both cover at least the light emitting region, in other words, the ranges of the setting region of the first transparent conductive layer and the setting region of the first grating layer are both greater than or equal to the setting range of the light emitting region, and the light emitting region corresponds to the setting region of the active layer.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

FIG. 1 is a cross-sectional view of a VCSEL provided in the prior art;

FIG. 2a is a cross-sectional view of one structure of a VCSEL provided in an embodiment of the present application;

FIG. 2b is a schematic diagram of the structure of the current flow in the VCSEL shown in FIG. 2 a;

FIG. 3a is a schematic diagram of a structure of a grating in a VCSEL according to an embodiment of the present application;

FIG. 3b is a schematic diagram of another structure of a grating body in a VCSEL according to an embodiment of the present application;

FIG. 3c is a schematic diagram of another structure of a grating in a VCSEL according to an embodiment of the present disclosure;

FIG. 4a is a cross-sectional view of another structure of a VCSEL provided in an embodiment of the present application;

FIG. 4b is a cross-sectional view of another structure of a VCSEL provided in an embodiment of the present application;

FIG. 5a is a top view of another structure of a VCSEL provided in an embodiment of the present application;

FIG. 5b is a top view of another structure of a VCSEL provided in an embodiment of the present application;

FIG. 5c is a top view of another structure of a VCSEL provided in an embodiment of the present application;

FIG. 5d is a top view of another structure of a VCSEL provided in an embodiment of the present application;

fig. 6 is a cross-sectional view of a vertical cavity surface emitting laser according to a second embodiment of the present application;

fig. 7 is a cross-sectional view of a vertical cavity surface emitting laser according to a third embodiment of the present application;

fig. 8 is a cross-sectional view of a vertical cavity surface emitting laser according to a fourth embodiment of the present application;

fig. 9 is a schematic structural diagram of a first transparent conductive layer in a vertical cavity surface emitting laser according to a fourth embodiment of the present application.

Description of reference numerals:

80. 100, 200, 300, 400-vertical cavity surface emitting lasers; 81. 6, 60, 207-substrate; 82-lower distributed bragg reflector; an 83-n type spacer layer; 84-an active region; an 85-p type spacer layer; 86-upper distributed bragg mirror; 87-upper metal electrode; 88-packaging; 89-a lower metal electrode; 90-a current confinement layer;

101. 201-a second reflector; 2-a second barrier layer; 109. 209, 309, 409-active layer; 103. 303, 403-first isolation layer; 106. 306, 406-first reflector; 51. 351, 451-first grating layer; 51' -a sub-wavelength grating layer; 510. 511, 512, 513, 404-grating body; 52. 352, 452-first transparent conductive layer; 521-a first conductive portion; 53. 353, 453 protective layers; 61-an electrode; 7-a package; 91-a second conductive layer; 911-a second conductive portion; 92-a layer of high refractive index material; 93-a layer of low refractive index material; 94-a second electrode; 95-distributed bragg reflector;

202-a second grating layer; 203-a second transparent conductive layer; 204-a planar layer; 205-a bonding layer;

305-a first electrode portion; 405-an electrical conductor; 408-conductive structure.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The existing vertical cavity surface emitting laser generally has the technical problem of larger series resistance of devices. Specifically, as shown in fig. 1, the upper DBR 86 has a structure characterized by multiple layers, that is, the upper DBR 86 is formed by alternately growing 20 pairs of high and low refractive index semiconductor layers each having an optical thickness of one quarter wavelength, and the periodic change of the refractive index is used to realize optical feedback, thereby obtaining the high reflectivity and wide bandwidth effects of the DBR. However, the upper dbr 86 includes a plurality of stacked film layers, which results in a large series resistance in the upper dbr 86; further, in order to avoid an influence on light emission, the upper metal electrode 87 is provided in a ring shape, and the upper metal electrode 87 is offset from the current flow path K defined by the current confinement layer 90. The device current on the upper metal electrode 87 is injected through the current flow path K defined by the ring-shaped current confinement layer 90, that is, the current flow path is subjected to a process from the upper metal electrode 87 at the edge to the current flow path K at the center, and the current flow path is long.

The present application is proposed to solve the above problems, and the present application replaces the upper dbr of the prior art with a reflector having a grating layer, specifically, compared with the stack of 20 pairs or more of high and low refractive index semiconductor materials in the upper reflector of the prior art, the number of layers stacked in the film layer in the reflector having the grating layer of the present application is smaller, so that the film thickness of the first reflector can be reduced to reduce the series resistance. In addition, even when the carriers in the reflector are no longer holes, the effective mass of the carriers can be reduced to reduce the series resistance. In addition, the range of the arrangement region of the upper metal electrode is made to correspond to the arrangement region of the active layer, so that the length of the current flowing path is reduced, the radial size of the current flowing path is increased, and the series resistance of the device is reduced. Embodiments of a vertical cavity surface emitting laser and an electronic apparatus according to the present application are described below with reference to the drawings.

Example one

Fig. 2a is a cross-sectional view of a structure of a vcsel provided in an embodiment of the present application, and fig. 2b is a schematic structural view of current flowing in the vcsel shown in fig. 2 a. Referring to fig. 2a and 2b, the vertical cavity surface emitting laser 100 according to the embodiment of the present application includes: the semiconductor device comprises a substrate 6, and a second reflector 101, a second isolation layer 2, an active layer 109, a first isolation layer 103 and a first reflector 106 which are sequentially stacked on the substrate 6, wherein a resonant cavity is defined between the second reflector 101 and the first reflector 106; the first reflector 106 includes a first grating layer 51 and a first transparent conductive layer 52 which are stacked on each other, a refractive index of a material of the first grating layer 51 is larger than a refractive index of a material of the first transparent conductive layer 52, and a current in the first transparent conductive layer 52 is injected into the active layer 109 through the first isolation layer 103; the first reflector 106 has a light emitting region O for emitting laser light; the light exit region O corresponds to the position where the active layer 109 is disposed, and both the first transparent conductive layer 52 and the first grating layer 51 cover at least the light exit region O.

The size of the light emitting region O is determined by the size and the position of the current passing region in the active layer 109, and specifically, referring to fig. 2b, the light emitting region O is a region of the first reflector 106 directly opposite to the current flow channel L in the active layer 109.

In the embodiment of the present application, the grating is also called a diffraction grating, and is an optical element that disperses (decomposes) light into a spectrum by using the principle of multi-slit diffraction. In the above solution, the first reflector 106 includes the first grating layer 51 and the first transparent conductive layer 52, and the first transparent conductive layer 52 and the first grating layer 51 both cover at least the light emitting region O, as shown by the solid arrows in fig. 2b, the injection current can be injected from the first transparent conductive layer 52 substantially vertically into the corresponding region of the active layer 109, so that the light emitting region O generates emitted laser light, and in the process, the injection current does not bypass but is injected into the active layer 109 along the longitudinal direction of the laser, so that the flow path of the current is short; therefore, the series resistance of the device can be reduced, the heat generation of the device can be reduced, and the thermal stability and the reliability of the device can be improved.

In addition, as described above, by providing the first reflector 106 as a reflector including the first grating layer 51, the number of layers stacked in the first reflector 106 having the first grating layer of the present application is smaller than that of a stack including 20 or more pairs of high and low refractive index semiconductor materials in the DBR of the related art, and thus the film thickness of the first reflector 106 is reduced, for example, the total thickness of the DBR reaches 3 to 4 micrometers, whereas the thickness of the first reflector 106 of the present application is smaller than 1 micrometer, for example, 500nm or less, and thus the series resistance is reduced, thereby reducing heat generation of the device to improve the thermal stability of the device.

In an alternative embodiment, referring to fig. 2a, the active layer 109 is disposed to a smaller extent than the first transparent conductive layer 52. Specifically, an orthographic projection of the active layer 109 on the first transparent conductive layer 52 is located within the arrangement region of the first transparent conductive layer 52, and an orthographic projection of the active layer 109 on the first grating layer 51 is located within the arrangement region of the first grating layer 51. The current flow path L corresponds to at least a partial region of the first transparent conductive layer 52, and the lateral dimension of the current flow path L is the same as the lateral dimension (radial dimension) of the region where the active layer 109 is disposed, which is larger than the lateral dimension of the current flow path K smaller than the lateral dimension of the region of the active layer 109 in the related art.

In another alternative embodiment, the arrangement range of the active layer is larger than that of the first transparent conductive layer, and an orthographic projection of the first transparent conductive layer on the active layer is located in an arrangement area of the active layer, and a light emergent area is located in an area, opposite to the first transparent conductive layer, of the first reflector.

In the embodiment of the present application, the orthographic projection of the active layer 109 on the first transparent conductive layer 52 refers to a projection pattern obtained by projecting the active layer 109 in the thickness direction of the vertical cavity surface emitting laser 100. The orthographic projection of the active layer 109 on the first transparent conductive layer 52 is located in the arrangement region of the first transparent conductive layer 52, which means that the orthographic projection pattern of the active layer 109 on the first transparent conductive layer 52 is located in the arrangement region of the first transparent conductive layer 52. Alternatively, the first transparent conductive layer 52 covers the active layer 109 when the vertical cavity surface emitting laser 100 is viewed from above. Similarly, the orthographic projection of the active layer 109 on the first grating layer 51 is located in the arrangement region of the first grating layer 51, which means that the orthographic projection pattern of the active layer 109 on the first grating layer 51 is located in the arrangement region of the first grating layer 51. Alternatively, the first grating layer 51 covers the active layer 109 when the vertical cavity surface emitting laser 100 is viewed from above.

It is understood that the disposed region of the first transparent conductive layer 52 refers to a region enclosed by the outer edge of the first transparent conductive layer 52, i.e., a region defined by the outer edge of the first transparent conductive layer 52. The first transparent conductive layer 52 may be a full layer arrangement, i.e., the first transparent conductive layer 52 is a continuous film layer; the first transparent conductive film layer can also be provided with a through notch locally. It should be noted that the continuous film layer refers to a state in which the film layer is always continuous within its range, i.e., there is no discontinuous region in the film layer.

In fig. 2a, a case where the transparent conductive layer is provided as a whole layer and is a continuous film layer is described as an example. In the embodiment of the present application, referring to fig. 2a, the first transparent conductive layer 52 and the first grating layer 51 are sequentially disposed on a surface of the first isolation layer 103, which faces away from the second reflector 101. That is, the first grating layer 51 is disposed on a surface of the first isolation layer 103 departing from the second reflector 101, and the first transparent conductive layer 52 is disposed on a surface of the first grating layer 51 departing from the first isolation layer 103.

As shown in fig. 2a, the range of the first transparent conductive layer 52 is larger than the range of the active layer 109, and the vertical cavity surface emitting laser 100 further includes an encapsulation portion 7 surrounding the second isolation layer 2, the active layer 109, and the first isolation layer 103. The first transparent conductive layer 52 may extend laterally to cover the top end face of the encapsulation 7.

As described above, the encapsulation portion 7 is provided around the outside of the active layer 109, and therefore, in this embodiment, the shape of the current flow channel L is defined by the encapsulation portion 7, and the shape of the current flow channel L corresponds to the active layer 109.

Referring to fig. 1 of the prior art, a flow path of current is indicated by a dotted arrow, in the upper dbr 86, the device current flows through the upper dbr 86 in a transverse direction of the device and then flows in a longitudinal direction of the device, that is, the device current flows through the upper dbr 86 after being bent and detoured before flowing into the current flow channel K, specifically, the device current flows from the upper metal electrode 87 disposed at the edge portion of the upper dbr 86 to the middle portion of the upper dbr 86 to flow into the current flow channel K defined by the current confinement layer 90 and then flows into the lower dbr 82, and the radial dimension of the current flow channel K is smaller than that of the active layer 84. Referring to fig. 2b, the device current enters the second reflector 101 from the first transparent conductive layer 52 directly through the current flow channel L without going around, i.e. the flow process omits the process of flowing along the lateral direction of the device, and in addition, the radial dimension of the current flow channel L is the same as that of the active layer 109. It can be seen from this that, in the vertical cavity surface emitting laser 100 shown in fig. 2a and 2b, the current flowing path is short, and the radial dimension of the current flowing channel L is large, so that the series resistance of the device can be reduced, the heat generation of the device can be reduced, and the thermal stability and reliability of the device can be improved in the vertical cavity surface emitting laser emitter according to this embodiment.

Compared with the prior art, the first grating layer 51 adopts the transparent conductive film (the first transparent conductive layer 52) as a low refractive index layer used in cooperation with the transparent conductive film, and the first transparent conductive layer 52 can also be used as a device electrode, so that current vertical cavity surface injection can be realized, the series resistance of the device is reduced, a current limiting aperture is not required to be formed by means of a wet oxidation or ion injection process, and the process difficulty is greatly reduced. Here, it is understood that the first transparent conductive layer 52 herein functions as an upper electrode of the vertical cavity surface emitting laser, and the second conductive layer 91 described below functions as a lower electrode of the vertical cavity surface emitting laser. The connection mode of the upper electrode and the lower electrode with the external circuit can be determined according to the connection condition of the actual circuit.

In addition, referring to fig. 1, the annular opaque upper metal electrode 87 functions as an upper electrode, cannot transmit light, but occupies a certain lateral dimension of the laser, and in the first reflector 106, since the first transparent conductive layer 52 does not affect the light output of the laser, compared with the prior art, the laser in the prior art has a larger dimension under the condition of the same size of current flowing channel. In other words, under the condition that the external contour dimension of the laser is the same, the dimension of the current flowing channel in the laser can be larger, a better transverse light field constraint effect can be achieved, the laser threshold value can be reduced more favorably, and the laser quantum efficiency and the slope efficiency can be improved.

Further, referring to fig. 2a, the first transparent conductive layer 52 is in direct contact with the first isolation layer 103, so that the current in the first transparent conductive layer 52 is injected into the active layer 109 through the first isolation layer 103. As described above, the first transparent conductive layer 52 is in direct contact with the first isolation layer 103, and the series resistance can be further reduced as compared with the case where the metal electrode is in contact with the isolation layer through the current diffusion structure in the related art. In the example of fig. 2a, the first transparent conductive layer 52 directly covers the surface of the first isolation layer 103.

In the embodiment of the present application, referring to fig. 2b, as an alternative implementation, the first grating layer 51 may be a sub-wavelength grating layer 51'. The sub-wavelength grating layer 51' is made of a high index-contrast dielectric material or a suspended high index material and can serve as the first reflector 106 of the VCSEL 100. The sub-wavelength grating layer 51' can realize a broadband reflectivity of more than 99% by adjusting the grating period T, the thickness H of the grating high refractive index material and the grating duty ratio (the ratio of the width W of the high refractive index material to the grating period T), and can realize polarization selection and transverse mode selection. In addition, the use of the sub-wavelength grating layer 51' can greatly reduce the reflector thickness, reduce the difficulty of epitaxial growth of the VCSEL 100, and simultaneously can achieve polarization and transverse mode selection. Moreover, the sub-wavelength grating layer 51' can stabilize the laser polarization characteristic, and simultaneously realize good single-transverse base film emission, improve the laser peak field intensity and reduce the divergence angle. Finally, the whole thickness of the device can be reduced by changing the DBR structure in the prior art into the sub-wavelength grating layer 51' structure, and the heat dissipation performance of the device is improved.

In this embodiment, the grating structure in the first grating layer 51 may be set according to actual needs. Fig. 3a is a schematic diagram of a structure of a grating body in a vertical cavity surface emitting laser according to an embodiment of the present application, fig. 3b is a schematic diagram of another structure of a grating body in a vertical cavity surface emitting laser according to an embodiment of the present application, and fig. 3c is a schematic diagram of another structure of a grating body in a vertical cavity surface emitting laser according to an embodiment of the present application.

Illustratively, the first grating layer 51 includes a plurality of grating bodies 510 disposed at intervals, the grating bodies 510 may form grating ridges of the first grating layer 51, and the spaces between adjacent grating bodies 510 form grating valleys of the first grating layer 51. The grating bodies may be in the shape of strips, and as shown in fig. 3a, the strip-shaped grating bodies 511 are arranged in parallel with each other and periodically.

In other examples, the grating bodies may be formed in an island shape, the cross section of the island-shaped grating body is one of a square, a circle and a hexagon, as shown in fig. 3b, the cross section of each grating body 512 is a square, and the plurality of grating bodies 512 are arranged in an array; alternatively, as shown in fig. 3c, the cross section of each grating body 513 is hexagonal, and the plurality of grating bodies 513 are arranged in a honeycomb shape.

In the embodiment of the present application, referring to fig. 2a, as an implementation manner of an embodiment, in order to protect the first reflector 106, the first reflector 106 further includes a protective layer 53, the protective layer 53 is disposed on the first transparent conductive layer 52 or the first grating layer 51, and a refractive index of a material of the protective layer 53 is lower than a refractive index of a material of the first grating layer 51.

The protective layer 53 covers the first transparent conductive layer 52 or the first grating layer 51, and the protective layer 53 covers the first grating layer 51, which means that the protective layer 53 covers the grating bodies 510 and covers the space between the grating bodies 510, so that the protective layer 53 with a lower refractive index is filled around the grating bodies 510 with a higher refractive index.

In the embodiment of the present application, the first isolation layer 103 may be a p-type isolation layer, and the second isolation layer 2 may be an n-type isolation layer. The active layer 109 is used for emitting laser light, and may include an indium gallium arsenic multiple quantum well layer or a single quantum well layer for forming a stable standing wave in the thickness direction of the vertical cavity surface emitting laser 100, that is, in the direction perpendicular to the laser light emitting surface.

In the embodiment of the present application, the type of the second reflector 101 may be selected according to actual needs, and the second reflector 101 may include the second conductive layer 91, and it should be noted that, for better matching with the first transparent conductive layer 52, the second conductive layer 91 may also be provided as a continuous film layer. Referring to fig. 2a, in order to facilitate electrical connection, the second conductive layer 91 may include a second conductive portion 911 protruding from the sealing portion 7. Similarly to the second conductive layer 91, the first transparent conductive layer 52 may include a first conductive portion 521 protruding from the protective layer 53.

In the embodiment of the present application, the second reflector 101 may be a distributed bragg reflector.

Fig. 4a is a cross-sectional view of another structure of a vertical cavity surface emitting laser according to an embodiment of the present application. Referring to fig. 4a, the second reflector 101 may include a distributed bragg reflector 95.

Illustratively, the distributed bragg reflector 95 includes a plurality of high refractive index material layers 92 and a plurality of low refractive index material layers 93, the number of the high refractive index material layers 92 is the same as that of the low refractive index material layers 93, each of the high refractive index material layers 92 and each of the low refractive index material layers 93 are alternately stacked, and the number of the low refractive index material layers 93 in the second reflector 101 is 20 to 30. Here, the refractive index of the material of the high refractive index material layer 92 is larger than that of the material of the low refractive index material layer 93. It is understood that the high refractive index material layer 92 and the low refractive index material layer 93 are both made of group iii-v semiconductor materials. And the material doping of the high refractive index material layer 92 and the low refractive index material layer 93 is p doping or n doping, and the thickness of each material layer is 1/4 of the wavelength of the outgoing laser. And the reflectivity of the second reflector 101 including the DBR structure at normal incidence of the outgoing laser wavelength is higher than that of the first reflector 106.

The second conductive layer 91 may be disposed between the distributed bragg reflector 95 and the substrate 6, the distributed bragg reflector 95 and the second electrode 94 may be stacked on the second conductive layer 91 at an interval, the second conductive layer 91 and the second electrode 94 may be electrically connected to each other, and the second electrode 94 may be electrically connected to an external circuit. Illustratively, the substrate 6 may be an intrinsic III-V substrate.

Fig. 4b is a cross-sectional view of another structure of a vcsel according to an embodiment of the present application, in the vcsel shown in fig. 4b, based on the vcsel shown in fig. 2a or fig. 4a, a second transparent conductive layer is omitted from a second reflector 101, a material of a substrate 60 may be a highly doped n-type substrate material, and other structures are similar to those shown in fig. 2a or fig. 4a and are not repeated here. By this arrangement, the current in the second reflector 101 can pass directly through the substrate 60 to the electrode 61 arranged on the back side of the substrate 60.

By highly doped n-type substrate material is meant herein that the substrate material is an n-doped substrate and has a doping concentration greater than 1x10¹⁷cm^-3So that the current passes directly through the substrate 60 and to the electrode 61 on the back side of the substrate 60.

In the embodiment of the present application, as described above, the first reflector 106 does not have a current confinement layer, and does not need an oxidation process, so that the cross-sectional shape of the current flow channel L can be set as required, that is, the vertical cavity surface emitting laser in this embodiment can implement an optical aperture with any shape.

Fig. 5 a-5 d are top views of alternative configurations of vcsels provided in embodiments of the present application. Illustratively, the cross-sectional shape of the active layer may be square, as shown in fig. 5 a; alternatively, the cross-sectional shape of the active layer may be circular, as shown in fig. 5 b; or the cross-sectional shape of the active layer may be triangular, as shown in fig. 5 c; alternatively, the cross-sectional shape of the active layer may be hexagonal, as shown in fig. 5 d. It is understood that the entire vcsel has no symmetry as described above, and thus the polarization characteristics of the emitted laser light are stable.

The selection of parameters for each functional film layer is described below.

Illustratively, the reflectivity of the second reflector 101 for laser light emitted by the VCSEL 100 is higher than the reflectivity of the first reflector 106 for laser light emitted by the VCSEL 100. Illustratively, the normal incidence reflectivity of the first reflector 106 for laser light emitted by the VCSEL 100 should be greater than 99% and the absorption should be less than 0.5%.

The first transparent conductive layer 52 is made of a material with a resistivity lower than 5x10^-3Non-metallic material of Ω · cm; and/or the first transparent conductive layer 52 has an extinction coefficient of less than 0.03 to laser light emitted by the VCSEL 100; and/or the first transparent conductive layer 52 has an absorptance with respect to laser light emitted from the vcsel 100 of less than 0.5%.

In addition, in order not to affect the light emission of the vertical cavity surface emitting laser 100, the material of the first transparent conductive layer 52 may be optionally a transparent conductive oxide. The refractive index of the material of the first transparent conductive layer 52 is much lower than that of the first grating layer 51, and thus the material can be directly used as an electrode on the vcsel 100.

Alternatively, the material of the first transparent conductive layer 52 may be a Transparent Conductive Oxide (TCO) such as Indium Tin Oxide (ITO) and aluminum-doped zinc oxide (AZO).

In the embodiment of the present application, it is optional that the refractive index of the material of the first grating layer 51 is greater than or equal to 1.4 times the refractive index of the material of the first transparent conductive layer 52, and the first grating layer 51 has an extinction coefficient smaller than 0.1 for the laser light emitted by the vertical cavity surface emitting laser 100. And/or the material of the first grating layer 51 is at least one of silicon, gallium nitride, indium phosphide, molybdenum sulfide, gallium phosphide.

Optionally, the refractive index of the material of the first grating layer 51 is greater than or equal to 1.4 times the refractive index of the material of the protective layer 53. And the extinction coefficient of the first grating layer 51 is less than 0.05.

In this embodiment, the vertical cavity surface emitting laser includes: the semiconductor device comprises a substrate, and a second reflector, a second isolation layer, an active layer, a first isolation layer and a first reflector which are sequentially stacked on the substrate, wherein a resonant cavity is defined between the second reflector and the first reflector; the first reflector comprises a first grating layer and a first transparent conducting layer which are mutually stacked, and the refractive index of the material of the first grating layer is larger than that of the material of the first transparent conducting layer; the first reflector is provided with a light emitting area for emitting laser; the light emitting area corresponds to the arrangement area of the active layer, and the first transparent conductive layer and the first grating layer at least cover the light emitting area. In the above solution, the first reflector includes the first grating layer and the first transparent conductive layer, and the first transparent conductive layer and the first grating layer both cover at least the light emitting region, in other words, the ranges of the setting region of the first transparent conductive layer and the setting region of the first grating layer are both greater than or equal to the setting range of the light emitting region, and the light emitting region corresponds to the setting region of the active layer.

Example two

In the vertical cavity surface emitting laser 200 provided in this embodiment, on the basis of the first embodiment, the structures of the second reflector, the substrate, and the like are improved, and the rest is the same as the first embodiment.

Fig. 6 is a cross-sectional view of a vertical cavity surface emitting laser according to a second embodiment of the present application. Referring to fig. 6, the second reflector 201 includes a second grating layer 202 and a second transparent conductive layer 203 formed on the second grating layer 202, a refractive index of a material of the second grating layer 202 is greater than a refractive index of a material of the second transparent conductive layer 203, and a forward projection of the active layer 209 on the second transparent conductive layer 203 is located in an arrangement region of the second transparent conductive layer 203. And, the orthographic projection of the active layer 209 on the second grating layer 202 is located within the setting area of the second grating layer 202.

Similar to the embodiment, the second reflector 201 includes the second grating layer 202 and the second transparent conductive layer 203, and the orthographic projection of the active layer 209 on the second transparent conductive layer 203 is located in the arrangement region of the second transparent conductive layer 203, in other words, the range of the arrangement region of the second transparent conductive layer 203 is made to be greater than or equal to the arrangement range of the active layer 209, in combination with the arrangement of the first transparent conductive layer 52 in the first embodiment, the injection current can be directly injected into the second transparent conductive layer 203 from the active layer 209, that is, the positions of the second transparent conductive layer 203, the first transparent conductive layer 52 and the current flow channel L in the device thickness direction correspond to each other, and the radial dimension of the active layer 209 is smaller than the radial dimensions of the second transparent conductive layer 203 and the first transparent conductive layer 52, when the lateral dimension of the injection current flow channel L is the same as the lateral dimension of the arrangement region of the active layer 209, compared with the prior art that the transverse size of the current flow channel is smaller than that of the active layer region, the transverse size of the current flow channel L is larger, so that the series resistance of the device can be reduced, the heat generation of the device is reduced, and the thermal stability and the reliability of the device are improved.

The orthographic projection of the active layer 209 on the second transparent conductive layer 203 is a projection pattern obtained by projecting the active layer 209 in the thickness direction of the vertical cavity surface emitting laser. The orthographic projection of the active layer 209 on the second transparent conductive layer 203 is located in the arrangement area of the second transparent conductive layer 203, which means that the orthographic projection pattern of the active layer 209 on the second transparent conductive layer 203 is located in the arrangement area of the second transparent conductive layer 203. Alternatively, the second transparent conductive layer 203 covers the active layer 209 when the vertical cavity surface emitting laser is viewed from below.

It is understood that the disposed region of the second transparent conductive layer 203 refers to a region surrounded by the outer edge of the second transparent conductive layer 203. The second transparent conductive layer 203 may be provided as a whole layer, that is, the second transparent conductive layer 203 is a continuous film layer; or a through notch may be partially provided in the second transparent conductive film layer 203.

In the embodiment of the present application, optionally, the orthographic projection of the active layer 209 on the second grating layer 202 is located in the setting area of the second grating layer 202. Even if the coverage of the second grating layer 202 is greater than or equal to the arrangement of the active layer, the current flow channel L has a radial dimension as large as possible.

It should be noted that the kind of material and the requirement of the second transparent conductive layer 203 are the same as those of the first transparent conductive layer 52, and the description thereof is omitted here. Illustratively, second grating layer 202 may be a sub-wavelength grating. The kind of material and the requirements for the material of the second grating layer 202 are the same as those of the first grating layer 51. A sub-wavelength grating refers to a periodic (or non-periodic) structure having a feature size comparable to or smaller than the operating wavelength, and the reflectivity, transmittance, polarization properties, spectral properties, etc. of the sub-wavelength grating all exhibit characteristics distinct from those of conventional diffractive optical elements.

To further reduce the series resistance, the second transparent conductive layer 203 may be brought into direct contact with the second isolation layer 2, so that the current in the active layer 209 may be directly injected into the second transparent conductive layer 203 through the second isolation layer 2.

Referring to fig. 6, for example, a second transparent conductive layer 203 and a second grating layer 202 are sequentially disposed on a side of the second isolation layer 2 away from the first reflector 106. Here, the grating structure in the second grating layer 202 may be the same as the structures in fig. 3a, 3b, and 3c in the first embodiment, and is not described here again.

Further, the second reflector 201 further includes a flat layer 204, where the flat layer 204 is disposed on a side of the second transparent conductive layer 203 away from the first reflector 106 and covers the second grating layer 202, that is, the flat layer 204 is to cover each grating body in the second grating layer 202 and also covers the space between each grating body.

It is noted that the refractive index of the material of the planarization layer 204 is lower than the refractive index of the material of the second grating layer 202. Illustratively, the refractive index of the material of the planarization layer 204 is less than 0.7 times the refractive index of the material of the second grating layer 202, and the planarization layer 204 has an extinction coefficient less than 0.1 for lasing in a VCSEL.

In this embodiment, the vcsel 200 further optionally includes a substrate 207 and a bonding layer 205, and the bonding layer 205 is disposed between the substrate 207 and the planarization layer 204 and is used for bonding the substrate 207 and the planarization layer 204. Illustratively, the material of the bonding layer 205 may be metal or oxide.

In this embodiment, the second reflector 201 includes a second grating layer 202 and a second transparent conductive layer 203 formed on the second grating layer 202, a refractive index of a material of the second grating layer 202 is greater than a refractive index of a material of the second transparent conductive layer 203, and a forward projection of the active layer 209 on the second transparent conductive layer 203 is located in an arrangement region of the second transparent conductive layer 203. Thus, the range of the arrangement region of the second transparent conductive layer 203 is larger than or equal to the range of the arrangement region of the active layer 209, in combination with the arrangement of the first transparent conductive layer 52 in the first implementation, the injection current can be directly injected into the second transparent conductive layer 203 from the active layer 209, that is, the positions of the second transparent conductive layer 203, the first transparent conductive layer 52 and the current flow channel L in the device thickness direction correspond to each other, and the radial dimension of the active layer 209 is smaller than the radial dimensions of the second transparent conductive layer 203 and the first transparent conductive layer 52, at this time, the lateral dimension of the injection current flow channel L is the same as the lateral dimension of the arrangement region of the active layer 209, which is larger than the lateral dimension of the current flow channel in the prior art which is smaller than the lateral dimension of the active layer region, so that the series resistance of the device can be reduced, the heat generation of the device can be reduced, the thermal stability and reliability of the device are improved.

EXAMPLE III

In the vcsel 300 provided in this embodiment, on the basis of the first and second embodiments, the structure of the first reflector is improved, and the rest is the same as that of the first and second embodiments, and for the rest, since the detailed description has been already made in the first and second embodiments, the detailed description is omitted here.

Fig. 7 is a cross-sectional view of a vertical cavity surface emitting laser according to the third embodiment of the present application. Referring to fig. 7, a first grating layer 351 and a first transparent conductive layer 352 are sequentially disposed on a surface of the first isolation layer 303 facing away from the second reflector 101. That is, the first grating layer 351 is disposed on a surface of the first isolation layer 303 facing away from the second reflector 101, and the first transparent conductive layer 352 is disposed on a surface of the first grating layer 351 facing away from the first isolation layer 303.

In this embodiment, the material of the first grating layer 351 is the same as the material of the first isolation layer 303. This allows first grating layer 351 to be formed by etching the material used to form first spacer layer 303. That is, the first grating layer 351 and the first isolation layer 303 may be formed as one body. Of course, the first grating layer 351 and the first isolation layer 303 may be formed separately and made of different materials.

Optionally, the first transparent conductive layer 352 may be a continuous film layer, and the first transparent conductive layer 352 covers the first grating layer 351. That is, the first transparent conductive layer 352 covers not only the top of the grating bodies in the first grating layer 351 but also the gaps between the grating bodies. In this embodiment, the first transparent conductive layer 352 is a continuous film layer disposed in a whole layer.

Similar to the embodiment, the first reflector 306 also includes a protection layer 353, and the protection layer 353 covers a side of the first transparent conductive layer 352 facing away from the active layer 309. And the refractive index of the material of protective layer 353 is lower than the refractive index of the material of first grating layer 351.

The first transparent conductive layer 352 further includes a first electrode portion 305 not covered with the protective layer 353, and the first electrode portion 305 is used for electrical connection to an external circuit.

In this embodiment, the material of the first grating layer 351 is the same as the material of the first isolation layer 303. Thus, the first grating layer 351 can be formed by etching the material for forming the first isolation layer 303, the process is simple, and the cost can be saved.

Example four

In the vertical cavity surface emitting laser 400 provided in this embodiment, on the basis of the third embodiment, the structure of the first reflector is improved, the rest is the same as that in the third embodiment, and for the rest, since the description has been already made in the third embodiment, the description is omitted here.

Fig. 8 is a cross-sectional view of a vertical cavity surface emitting laser according to a fourth embodiment of the present application. Referring to fig. 8, in the embodiment of the present application, the material of the first grating layer 451 is the same as the material of the first isolation layer 403. This allows the first grating layer 451 to be formed by etching the material used to form the first spacer layer 403. That is, the first grating layer 451 and the first spacer layer 403 may be formed as one body. Of course, the first grating layer 451 and the first spacer layer 403 may be formed separately from each other by using different materials.

Optionally, the first grating layer 451 includes a plurality of grating bodies 404 arranged at intervals, the first transparent conductive layer 452 is a hollow structure to form a plurality of conductive bodies 405 arranged at intervals, and the conductive bodies 405 are in one-to-one correspondence with the grating bodies 404 to form a grating structure in the first transparent conductive layer 452.

Fig. 9 is a schematic structural diagram of a first transparent conductive layer in a vertical cavity surface emitting laser according to a fourth embodiment of the present application.

Referring to fig. 9, it should be noted that the structures of the grating body 404 and the conductive bodies 405 in this embodiment can only adopt a strip structure, and the conductive bodies 405 are also electrically connected through the conductive structure 408. Illustratively, the conductors 405 are spaced apart and arranged in parallel, and the conductive structure 408 may be, for example, a frame-like member that surrounds the conductors 405 and electrically connects the two ends of each conductor 405.

Similar to the embodiment, the first reflector 406 also includes a protection layer 453, and the protection layer 453 covers a side of the first transparent conductive layer 452 facing away from the active layer 409. Note that the protective layer 453 covers not only the conductors 405 but also the spaces between the grating bodies 404 and the spaces between the conductors 405. And the refractive index of the material of the protective layer 453 is lower than the refractive index of the material of the first grating layer 451.

In this embodiment, the material of the first grating layer 451 is the same as the material of the first isolation layer 403. Thus, the first grating layer 451 can be formed by etching the material for forming the first spacer 403, and the process is simple and cost-saving. In addition, the first transparent conductive layer 452 is formed into a hollow structure, and the conductive bodies 405 are in one-to-one correspondence with the grating bodies 404, so that in addition to the first grating layer 451, another grating layer is formed on the first grating layer 451, and the performance of the first reflector 406 is better.

EXAMPLE five

An embodiment of the present application also provides an electronic device including the vertical cavity surface emitting laser described in any of the above embodiments. The structural and functional principles of the vertical cavity surface emitting laser and the like have been described in detail in the first to fourth embodiments, and are not described herein again.

The electronic device can be specifically an electronic product or a component such as a mobile phone, a tablet personal computer, a television, a notebook computer, a digital photo frame, a fingerprint lock and the like. The electronic equipment comprises the vertical cavity surface emitting laser, the circulation path of the device current is shortened, and the radial size of the current circulation path is increased, so that the series resistance of the device can be reduced, the heat generation of the device is reduced, and the thermal stability and the reliability of the device are improved.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.