CN117767115A - VCSEL laser with uniform current distribution, preparation method and laser radar - Google Patents
VCSEL laser with uniform current distribution, preparation method and laser radar Download PDFInfo
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Abstract
The utility model belongs to the technical field of semiconductors, specifically a VCSEL laser that current distribution is even, including at least one luminescence unit, the luminescence unit includes substrate layer, first electrode, first Bragg reflector, active region, current limiting layer, second Bragg reflector, second electrode and current diffusion layer, the second electrode is in form confined ring on the second Bragg reflector, the current diffusion layer is located the intra-annular that the second electrode formed and contacts with the second Bragg reflector, the current diffusion of second electrode is to this current diffusion layer on, wherein the current that diffuses to the current diffusion layer gets into by the intermediate zone in limiting hole through the second Bragg reflector in the active region.
Description
Technical Field
The application belongs to the technical field of semiconductors, and particularly relates to a VCSEL laser with uniform current distribution, a preparation method and a laser radar.
Background
VCSEL (Vertical-Cavity Surface Emitting Laser) is a semiconductor Laser Emitting Laser along the direction Vertical to a substrate, has the advantages of concentrated light beam, small divergence angle, small active area volume, capability of being lightened according to a two-dimensional array, low cost and the like, and is widely applied to the fields of vehicle-mounted Laser radar, vehicle-mounted personnel monitoring (OMS, DMS), consumer-level face recognition, large data transmission and the like.
The structure of the VCSEL sequentially comprises an N-type metal electrode layer, an N-type substrate layer, an N-DBR layer, an active region, a current limiting layer, a P-DBR layer and a P-type metal electrode from bottom to top, wherein the N-type metal electrode is used as a cathode of the VCSEL, the P-type metal electrode is used as an anode of the VCSEL, current is input from the P-type metal electrode, enters the active region through the P-DBR layer and the current limiting layer, electrons are converted into photons in the active region, the photons are continuously reflected and amplified between the N-DBR layer and the P-DBR layer, and after reaching a threshold value, laser is emitted from the P-DBR layer with low reflectivity (namely, the laser is emitted in a direction perpendicular to the substrate layer).
In a typical VCSEL structure, after current enters through the P-DBR, the current tends to enter the active region through the edge of the current confinement hole, the current density is higher at the portion of the current confinement hole that is biased to the periphery, and lower at the middle portion of the current confinement hole, and the excessively concentrated current may cause the partial region to generate heat, so that dark spots are more easily generated at the edge region, and the temperature is also higher, resulting in reduced reliability of the VCSEL laser.
Therefore, there is a need to propose new VCSEL structure designs to improve the reliability of VCSEL lasers.
Content of the application
An advantage of the present application is that it provides a VCSEL laser with uniform current distribution, in which a current diffusion layer is electrically contacted on a second bragg reflector (P-DBR), so as to increase the number of electrons passing through a middle region of a limiting hole, and further improve the uniformity of light emission of a light emitting unit.
Another advantage of the present application is to provide a VCSEL laser with a uniform current distribution, in which the current on the electrically contacted current spreading layer moves along the shortest path, thus shortening the current flow path and improving the current transfer efficiency.
Another advantage of the present application is to provide a VCSEL laser with a uniform current distribution, in which the current of the second electrode (P-Metal) is split, reducing the current density at the edge of the limiting aperture, reducing the heat at the edge of the limiting aperture, and improving the reliability of the light emitting unit.
Another advantage of the present application is to provide a VCSEL laser with uniform current distribution, in which the current diffusion layer is directly plated on the second bragg reflector (i.e., the P-DBR) in the process, which can be implemented by adding only one step of the process, and the process is simple, and the performance of the light emitting unit is greatly improved.
To achieve at least one of the above or other advantages and objects, according to one aspect of the present application, there is provided a VCSEL laser having a uniform current distribution, including at least one light emitting unit including
A substrate layer having a top surface and a bottom surface;
a first electrode on a bottom surface of the substrate layer;
a first Bragg reflector on a top surface of the substrate layer;
an active region located on a side of the first Bragg reflector remote from the substrate layer;
a current confinement layer providing optical and electrical confinement of a VCSEL of the VCSEL laser, the current confinement layer having a confinement aperture thereon;
a second Bragg reflector on a side of the active region remote from the substrate layer;
a second electrode on a side of the second Bragg reflector facing away from the substrate layer, the second electrode forming a closed loop on the second Bragg reflector, an
And the current diffusion layer is positioned in the ring formed by the second electrode and is electrically contacted with the second electrode, and the current of the second electrode is diffused to the current diffusion layer and enters the active region from the middle region of the limiting hole through the second Bragg reflector.
In the VCSEL laser according to the present application, the current spreading layer is located above the current confinement layer, and the middle region of the current spreading layer corresponds to the confinement hole.
In the VCSEL laser with uniform current distribution according to the present application, an edge of the current diffusion layer is in electrical contact with the second electrode, and a thickness of the current diffusion layer is smaller than a thickness of the second electrode.
In the VCSEL laser according to the present application, the current spreading layer has a thickness of 0.001-5.0 μm.
In the VCSEL laser with uniform current distribution according to the present application, the current spreading layer is a conductive film that is penetrable by laser light generated in the active region.
In the VCSEL laser with uniform current distribution according to the present application, the current diffusion layer is one or more of indium tin oxide film and graphene film.
In the VCSEL laser with uniform current distribution according to the present application, an insulating protective layer is provided on the side of the current spreading layer facing away from the second bragg mirror.
In the VCSEL laser with uniform current distribution, the protective layer is SiO 2 ，Si 3 N 4 ，Al 2 O 3 One or more of AlN.
In the VCSEL laser according to the present application, the current confinement layer corresponds to the active region and is located at the lower portion of the second bragg mirror or at the upper portion of the active region.
In the VCSEL laser with uniform current distribution according to the present application, the current confinement layer is one or a combination of two of an oxidation confinement layer and an ion implantation layer.
In another aspect of the present application, a process for fabricating a VCSEL laser with uniform current distribution is provided, comprising the steps of:
s10, forming an epitaxial main body structure through an epitaxial growth process, wherein the epitaxial main body structure comprises a substrate layer, a first Bragg reflector, an active region and a second Bragg reflector;
s20, forming a current diffusion layer deposited on the upper surface of the epitaxial main body structure, removing part of the current diffusion layer and exposing part of the upper surface of the epitaxial main body structure;
s30, forming a second electrode deposited on the epitaxial main body structure, and partially depositing a second electrode on the current diffusion layer;
s40, etching and removing at least one part of the epitaxial structure to form at least one light emitting unit, wherein each light emitting unit comprises a substrate layer, a first Bragg reflector, an active region, a second Bragg reflector, a current diffusion layer and a second electrode;
s40, forming a current limiting layer with limiting holes above the active region through an etching hole digging and water oxidation process or ion implantation;
s50, depositing to form an insulating protective layer;
s60, defining the shape of the second electrode to form a P-type ohmic contact layer;
s70, forming a positive electrode electrically connected to the second electrode; and
and S80, grinding and thinning the bottom of the substrate layer and then depositing a first electrode to form a negative electrode.
According to yet another aspect of the present application, the present application proposes an electronic device comprising:
a laser projection device for projecting laser light, wherein the laser projection device is included in any of the VCSEL chips of high optical power as described above;
a laser receiving device for receiving a laser signal; and
a processor communicatively coupled to the laser projection device and the laser receiving device.
Further objects and advantages of the present application will become fully apparent from the following description and the accompanying drawings.
These and other objects, features, and advantages of the present application will become more fully apparent from the following detailed description, the accompanying drawings, and the appended claims.
Drawings
Fig. 1 is a schematic structural diagram of two light emitting units containing a current diffusion layer of a VCSEL laser with uniform current distribution.
FIG. 2 is a schematic diagram of a single light emitting unit containing a current spreading layer of a VCSEL laser with uniform current distribution
Fig. 3 is a top view of a current spreading layer of a VCSEL laser with uniform current distribution in accordance with the present application.
Fig. 4 is a schematic diagram of a structure of a VCSEL laser with current spreading of uniform current distribution coated with a current spreading layer on its epitaxial structure.
Fig. 5 is a schematic diagram of a structure based on the structure of fig. 4, in which a part of the epitaxial structure is removed from the plated current diffusion layer, a second electrode is then vapor deposited, and the second electrode is in electrical contact with the current diffusion layer.
Fig. 6 is a schematic diagram of an etched hole that is etched into the epitaxial structure based on the structure of fig. 5.
Fig. 7 is a schematic view of a structure based on fig. 6 in which the oxidation limiting layer and limiting hole are formed by water oxidation by etching the inner wall of the hole.
Fig. 8 is a schematic view of a structure based on the structure of fig. 7, in which the substrate layer is ground and thinned and plated with the first electrode.
Detailed Description
The terms and words used in the following description and claims are not limited to literal meanings, but are used only by the applicant to enable a clear and consistent understanding of the present application. It will be apparent to those skilled in the art, therefore, that the following description of the various embodiments of the present application is provided for the purpose of illustration only and not for the purpose of limiting the application as defined by the appended claims and their equivalents.
It will be understood that the terms "a" and "an" should be interpreted as referring to "at least one" or "one or more," i.e., in one embodiment, the number of elements may be one, while in another embodiment, the number of elements may be plural, and the term "a" should not be interpreted as limiting the number.
Although ordinal numbers such as "first," "second," etc., will be used to describe various components, those components are not limited herein. The term is used merely to distinguish one component from another. For example, a first component may be referred to as a second component, and likewise, a second component may be referred to as a first component, without departing from the teachings of the present application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
The terminology used herein is for the purpose of describing various embodiments only and is not intended to be limiting. As used herein, the singular is intended to include the plural unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, or groups thereof.
Summary of the application
As described above, the pump source inputs a current to the VCSEL chip, the input current passes through the P-DBR layer and then enters the active region through the confinement hole, and laser emission is formed in the active region. While the input current tends to move along the shortest path in the P-DBR layer to enter the active region through the confinement aperture. The P-type metal electrode is annular in shape on the P-DBR layer, and the confinement holes are located in the annular formed by the P-type metal electrode in a top view (i.e., in a direction from the P-type metal electrode toward the substrate). Most of the current input by the P-type metal electrode is concentrated at the edge of the limiting hole, so that the current density at the edge of the limiting hole is in a higher state, and the current density at the middle part of the limiting hole is lower; excessive concentrated current can cause high heat generation in the partial region, so that dark dead spots are more easily generated on the VCSEL chip, and the reliability of the VCSEL chip is reduced.
In theory, the current can be led directly above the limiting hole, and then the current directly passes through the limiting hole along the shortest path in the P-DBR layer and enters the active region, which reduces the current gathered at the edge of the limiting hole, reduces the current density at the edge of the limiting hole, thereby reducing the dark dead spots generated by the VCSEL and improving the reliability of the VCESL. Based on this, the present application proposes that by adding a current diffusion layer that is permeable to laser light on the P-DBR layer, the current is guided over the confinement hole by using the current diffusion layer, so that the current can directly pass through the confinement hole into the active region, avoiding the edge of the confinement hole.
Accordingly, the present application proposes a VCSEL laser having a uniform current distribution, wherein the VCSEL laser is composed of one or more individual light emitting cells, and each light emitting cell comprises a substrate layer, a first electrode on a bottom surface of the substrate layer, a first bragg mirror on a top surface of the substrate layer, a second bragg mirror, an active region between the first bragg mirror and the second bragg mirror, a current confinement layer formed on the second bragg mirror, and a second electrode, the second bragg mirror having a current diffusion layer thereon, the current diffusion layer being in electrical contact with the second electrode, and the current diffusion layer being located in a ring formed by the second electrode in a top view direction, whereby a current of the second electrode is shunted into the current diffusion layer, and then a current on the current diffusion layer passes through the second bragg mirror, avoiding the confinement hole along a shortest path, into the active region.
Having described the basic principles of the present application, various non-limiting embodiments of the present application will now be described in detail with reference to the accompanying drawings.
Illustrative VCSEL laser
As shown in fig. 1, a VCSEL laser with uniform current distribution according to an embodiment of the present application is illustrated. The VCSEL laser is provided with a current spreading layer for shunting the second electrode to achieve that part of the current bypasses the edge of the limiting aperture directly into the active region. Specifically, the VCSEL laser of the present embodiment is constituted of a plurality of light emitting units 10; in yet other variant embodiments, the VCSEL laser may be a single one of the light emitting units 10.
Wherein the light emitting unit 10 comprises an epitaxial structure, a first electrode 11, a second electrode 12, and a current diffusion layer 13; the first electrode 11 is an N-type metal layer, and the first electrode 11 is an N-type doped alloy formed by three metals of platinum, gold and nickel, or the first electrode is other N-type doped metals. The first electrode 11 is located at the bottom of the epitaxial structure, and when the VCSEL laser is formed of a plurality of light emitting units, the plurality of light emitting units share the same first electrode, i.e. the VCSEL laser is a co-cathode VCSEL. The second electrode 12 is a P-type doped alloy of three metals, such as platinum, gold, and nickel, but may be other metals, such as gold (Au). The second electrode 12 is electrically contacted with the upper portion of the epitaxial structure, the current diffusion layer 13 is positioned inside the second electrode 12 and is electrically contacted with the second electrode 12, and the bottom surface of the current diffusion layer 13 is contacted with the top surface of the epitaxial structure. The second electrode 12 and the current diffusion layer 13 constitute an anode of the light emitting unit 10, and current is entered into the epitaxial structure by the second electrode 12 and the current diffusion layer 13 and then is outputted by the first electrode 11.
The epitaxial structure comprises, from bottom to top, a substrate layer 14, a first bragg mirror 15, an active region 16, a current confinement layer 17 with a confinement aperture 171, and a second bragg mirror 18. The substrate layer 14 is an N-type doped gallium arsenide substrate; in yet other alternative embodiments, the substrate layer is a P-doped gallium arsenide substrate. The substrate layer 14 may be made of a doping type material such as InP, gaN, gaAs. The second electrode 12 and the current diffusion layer 13 are in contact with the top surface of the second bragg mirror 18, wherein the second bragg mirror 18 is grown to the top surface of the active region 16 by MOCVD, and the second bragg mirror 18 is a P-DBR formed of a plurality of alternating stacks of P-doped high aluminum content AlxGa1-xAs (x=1 to 0) and P-doped low aluminum content AlxGa1-xAs (x=1 to 0). Correspondingly, the first bragg mirror 15 is grown to the top surface of the substrate layer 14 by MOCVD. The first bragg mirror 15 is an N-DBR formed of alternating stacks of N-doped high aluminum content AlxGa1-xAs (x=1-0) and N-doped low aluminum content AlxGa1-xAs (x=1-0). It is worth mentioning that the material selection of the alternating layers depends on the operating wavelength of the laser light emitted by the light emitting unit, and the optical thickness of the alternating layers is equal to or about equal to 1/4 of the operating wavelength of the laser light.
In other modified embodiments, as shown in fig. 2, by designing and configuring the first bragg mirror 15 and the second bragg mirror 18, the difference between the reflectivity of the first bragg mirror 15 and the reflectivity of the second bragg mirror 18 is controlled, so as to control the light emitting direction of the laser light; for example, the reflectivity of the second bragg mirror is controlled to be higher than that of the first bragg mirror, namely, the second bragg mirror is an N-DBR, and the first bragg mirror is correspondingly a P-DBR. Since the refractive index of the second Bragg reflector is higher than that of the first Bragg reflector, the generated laser light is emitted from the direction towards the substrate layer. The active region 16 is sandwiched between the first bragg reflector 15 and the second bragg reflector 18 to form a resonant cavity, wherein photons are repeatedly amplified by being reflected back and forth in the resonant cavity after being excited to form laser oscillation, thereby forming laser light.
The second electrode 12 is formed in a ring shape on the top surface of the second bragg mirror 18; the limiting hole 171 is located in a ring formed by the second electrode 12 in a top view (i.e., a direction from the second electrode toward the first electrode). In other embodiments, the ring shape formed by the second electrode 12 may be polygonal or irregular, and it is noted that, no matter what shape the second electrode is, the limiting hole is located inside the second electrode in the top view direction to ensure that the second electrode does not block or absorb the laser generated in the active region. And the edge of the current diffusion layer 13 is in electrical contact with the second electrode 12, wherein the electrical contact is that the edge side wall of the current diffusion layer 13 is in contact with the inner wall of the second electrode 12, and the current of the second electrode 12 is conducted by the contacted part.
In a more preferable manner of the application, as shown in fig. 2-3, when the second electrode 12 is evaporated onto the second bragg reflector 18, the second electrode 12 partially falls onto the top surface of the edge of the current diffusion layer 13 except for the contact between the second electrode 12 and the inner wall of the second electrode 12, so as to increase the contact surface between the current diffusion layer 13 and the second electrode 12, improve the efficiency of diffusing the current of the second electrode 12 into the current diffusion layer 13, increase the amount of current entering the active region from the middle region of the limiting hole, and further improve the uniformity of forming the light spot.
The current diffusion layer 13 is a thin film with a thickness and no through hole defect, and the current diffusion layer 13 is transparent or the laser generated by the active region can penetrate. The middle region of the current diffusion layer 13 and the limiting hole overlap each other in a top view (i.e., a direction from the second electrode toward the first electrode), and the center of the current diffusion layer 13 and the center of the limiting hole 171 are positioned on the same line. In other deformed modes, the middle area of the current diffusion layer can also be a film with a through hole with an area smaller than that of the limiting hole, and the existence of the through hole can reduce the resistance of the current diffusion layer and reduce the obstruction of the current diffusion layer on laser emitted by the active area; thereby improving the optical power of the light emitting unit of the VCSEL laser.
In this embodiment, the current diffusion layer 13 is a conductive film that does not absorb light or block light, the laser generated by the active region 16 can penetrate through the current diffusion layer 13, preferably an ITO (indium tin oxide film), and in other variant embodiments, the current diffusion layer may also be a graphene film or other conductive films through which the laser can penetrate. In other embodiments, as described above, when the refractive index of the second bragg reflector is controlled to be higher than that of the first bragg reflector, that is, the second bragg reflector is an N-DBR, the first bragg reflector is a P-DBR, and the light emitting unit is a back light emitting unit, the current diffusion layer may be an alloy of three metals of platinum, gold and nickel, that is, the current diffusion layer is a part of the second electrode, or the current diffusion layer may be a conductive film with light blocking or light absorbing function.
In the embodiment of the present application, the thickness of the current diffusion layer 13 is smaller than the thickness of the second electrode 12, and the thickness of the current diffusion layer is 0.001-5.0 micrometers. Of course, in other variant embodiments, the thickness of the current diffusion layer may be selected according to the resistance value of the material of the current diffusion layer selected, for example, a low-resistance current diffusion layer may be selected, and the thickness of the current diffusion layer may be kept consistent with the thickness of the second electrode.
In this embodiment of the present application, an insulating protection layer 19 is disposed on a side of the current diffusion layer 13 away from the substrate layer, where the protection layer 19 protects the current diffusion layer from being damaged during operation, and adjusts the laser emitted in the active region 16, so as to improve the divergence angle and the optical power of the light emitting unit. In the embodiment of the present application, the protective layer 19 is preferably Si with insulating and optical modulating properties 3 N 4 (silicon nitride). In other variant embodiments, the protective layer may be SiO 2 ，Al 2 O 3 Any one of AlN. In still or in another variant embodiment, the protective layer may be SiO 2 ，Si 3 N 4 ，Al 2 O 3 A variety of compositions in AlN.
In this embodiment, after the VCSEL laser is turned on, the current is limited in flow direction by the current confinement layer, which is ultimately directed into the middle region of the VCSEL laser, so that the middle region of the active region is lasing. Specifically, the current confinement layer has a higher resistivity to confine carriers flowing into the middle region of the VCSEL laser, and the carrier lateral confinement increases the density of carriers and photons within the active region, improving the efficiency of light generation within the active region. The region of the current confinement layer that is not oxidized or ion implanted forms the confinement hole. The current limiting layer is formed after the lower part of the second Bragg reflector (namely, the area near one side of the active area) is locally destroyed by water oxidation or ion implantation. Of course, in other embodiments, the current confinement layer may be formed by locally damaging the upper portion of the active region (i.e., the region near the side of the second bragg mirror) by water oxidation or ion implantation.
The current limiting layer is an oxidation limiting layer formed after the inner wall of the hole is dug through etching and hole digging and water oxidation etching, or the current limiting layer is an ion injection layer formed after the second Bragg reflector is damaged by injecting ions into the second Bragg reflector, and one or more of the following ions are injected into the ion injection layer: h+, o+, b+.
In summary, the VCSEL laser according to the embodiments of the present application has been elucidated, which provides a design scheme that a feasible current uniformly passes through a limiting hole, and can improve reliability of the VCSEL laser and uniformity of a light spot emitted by the VCSEL laser when the VCSEL laser is operated, that is, form a light spot with substantially uniform outer ring and middle brightness while realizing changing current flow direction, reducing current density at an edge of the limiting hole, reducing heat productivity of the VCSEL laser when the VCSEL laser is operated.
Method for preparing schematic VCSEL laser
According to another aspect of the present application, there is also provided a method of manufacturing a high optical power VCSEL chip for use in the preparation of a VCSEL laser as described above. In the embodiment of the application, the conventional preparation process of the VCSEL can be still used in the preparation process of the VCSEL, and only the shape of the light emitting hole needs to be adjusted. Therefore, the original VCSEL production line and production equipment can be reserved for preparing the VCSEL laser, the production line transformation cost of the VCSEL laser is effectively reduced, and the preparation cost of the VCSEL laser is further reduced.
Specifically, in the embodiment of the present application, as shown in fig. 4 to 5, the method for manufacturing the high optical power VCSEL chip includes the following steps:
s10, forming an epitaxial main body structure through an epitaxial growth process, wherein the epitaxial main body structure comprises a substrate layer, a first Bragg reflector, an active region and a second Bragg reflector;
s20, forming a current diffusion layer deposited on the upper surface of the epitaxial main body structure, removing part of the current diffusion layer and exposing part of the upper surface of the epitaxial main body structure;
s30, forming a second electrode deposited on the epitaxial main body structure, and partially depositing a second electrode on the current diffusion layer;
s40, etching and removing at least one part of the epitaxial structure to form at least one light emitting unit, wherein each light emitting unit comprises a substrate layer, a first Bragg reflector, an active region, a second Bragg reflector, a current diffusion layer and a second electrode;
s40, forming a current limiting layer with limiting holes above the active region through an etching hole digging and water oxidation process or ion implantation;
s50, depositing to form an insulating protective layer;
s60, defining the shape of the second electrode to form a P-type ohmic contact layer;
s70, forming a positive electrode electrically connected to the second electrode; and
and S80, grinding and thinning the bottom of the substrate layer and then depositing a first electrode to form a negative electrode.
Schematic vehicle-mounted laser radar
According to yet another aspect of the present application, there is also provided a lidar. The working principle of the laser radar is as follows: the laser is used as a medium to emit laser to the measured target, the laser reflected by the measured target is received, and the relative position and distance between the measured target and the laser radar are obtained based on the time difference between the emitted laser and the received laser pulse (or the phase difference between the emitted laser and the received reflected laser), so that the detection, tracking and identification of the object to be measured in the target area are realized.
Accordingly, the lidar includes: the laser projection device comprises a VCSEL chip of optical power as described above, a laser projection device for projecting laser light, a laser receiving device for receiving a laser signal, and a processor communicatively connected to the laser projection device and the laser receiving device.
It is noted that in the apparatus and method of the present application, components or steps in different embodiments may be disassembled and/or assembled without departing from the principles of the present application. Such decomposition and/or recombination should be considered to be included within the application concept of the present application.
The basic principles of the present application have been described above in connection with specific embodiments, however, it should be noted that the advantages, benefits, effects, etc. mentioned in the present application are merely examples and not limiting, and these advantages, benefits, effects, etc. are not to be considered as necessarily possessed by the various embodiments of the present application. Furthermore, the specific details disclosed herein are for purposes of illustration and understanding only, and are not intended to be limiting, as the application is not intended to be limited to the details disclosed herein as such.
Claims (12)
1. A VCSEL laser with a uniform current distribution, comprising at least one light emitting unit comprising
A substrate layer having a top surface and a bottom surface;
a first electrode on a bottom surface of the substrate layer;
a first Bragg reflector on a top surface of the substrate layer;
an active region located on a side of the first Bragg reflector remote from the substrate layer;
a current confinement layer providing optical and electrical confinement of a VCSEL of the VCSEL laser, the current confinement layer having a confinement aperture thereon;
a second Bragg reflector on a side of the active region remote from the substrate layer;
a second electrode on a side of the second Bragg reflector facing away from the substrate layer, the second electrode forming a closed loop on the second Bragg reflector, an
And the current diffusion layer is positioned in the ring formed by the second electrode and is electrically contacted with the second electrode, and the current of the second electrode is diffused to the current diffusion layer and enters the active region from the middle region of the limiting hole through the second Bragg reflector.
2. A VCSEL laser with uniform current distribution as claimed in claim 1, wherein the current spreading layer is located above the current confinement layer and the middle region of the current spreading layer corresponds to the confinement holes.
3. A VCSEL laser with uniform current distribution as claimed in claim 1, wherein the edges of the current spreading layer are in electrical contact with the second electrode and the thickness of the current spreading layer is less than the thickness of the second electrode.
4. A VCSEL laser with uniform current distribution as claimed in claim 3, wherein the current spreading layer has a thickness of 0.001-5.0 microns.
5. A VCSEL laser with uniform current distribution as claimed in claim 1, wherein the current spreading layer is a laser-transparent conductive film created by the active region.
6. The VCSEL laser with uniform current distribution of claim 5, wherein the current spreading layer is one or a combination of indium tin oxide film and graphene film.
7. A VCSEL laser with uniform current distribution as claimed in claim 1, wherein the side of the current spreading layer remote from the second bragg mirror is provided with an insulating protective layer.
8. A VCSEL laser with uniform current distribution as claimed in claim 7, wherein the protective layer is SiO 2 ，Si 3 N 4 ，Al 2 O 3 One or more of AlN.
9. A VCSEL laser with uniform current distribution as claimed in claim 1, wherein the current confinement layer corresponds to the active region and is located below the second bragg mirror or above the active region.
10. A VCSEL laser with uniform current distribution as claimed in claim 1, wherein the current confinement layer is one or a combination of both of an oxidation confinement layer and an ion implantation layer.
11. A process for fabricating a VCSEL laser with uniform current distribution according to claims 1-10, comprising the steps of:
s10, forming an epitaxial main body structure through an epitaxial growth process, wherein the epitaxial main body structure comprises a substrate layer, a first Bragg reflector, an active region and a second Bragg reflector;
s20, forming a current diffusion layer deposited on the upper surface of the epitaxial main body structure, removing part of the current diffusion layer and exposing part of the upper surface of the epitaxial main body structure;
s30, forming a second electrode deposited on the epitaxial main body structure, and partially depositing a second electrode on the current diffusion layer;
s40, etching and removing at least one part of the epitaxial structure to form at least one light emitting unit, wherein each light emitting unit comprises a substrate layer, a first Bragg reflector, an active region, a second Bragg reflector, a current diffusion layer and a second electrode;
s40, forming a current limiting layer with limiting holes above the active region through an etching hole digging and water oxidation process or ion implantation;
s50, depositing to form an insulating protective layer;
s60, defining the shape of the second electrode to form a P-type ohmic contact layer;
s70, forming a positive electrode electrically connected to the second electrode; and
and S80, grinding and thinning the bottom of the substrate layer and then depositing a first electrode to form a negative electrode.
12. An electronic device, comprising:
a laser projection device for projecting laser light, wherein the laser projection device comprises a VCSEL laser of any of claims 1 to 9 having a uniform current distribution;
a laser receiving device for receiving a laser signal; and
a processor communicatively coupled to the laser projection device and the laser receiving device.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311857621.7A CN117767115A (en) | 2023-12-29 | 2023-12-29 | VCSEL laser with uniform current distribution, preparation method and laser radar |
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| CN202311857621.7A CN117767115A (en) | 2023-12-29 | 2023-12-29 | VCSEL laser with uniform current distribution, preparation method and laser radar |
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