Resistance-type VCSEL (Vertical Cavity Surface Emitting Laser), preparation method and laser equipment

Abstract

The invention belongs to the technical field of semiconductors, and particularly relates to a resistive VCSEL (vertical cavity surface emitting laser), which comprises a plurality of light-emitting arrays, each light-emitting array comprises a plurality of light-emitting units arranged in sequence, and each light-emitting unit comprises a substrate layer with a top surface and a bottom surface; a first Bragg reflector on the top surface of the substrate layer; the active region is positioned on one side, far away from the substrate layer, of the first Bragg reflector; the electrical limiting layer provides optical and electrical limitation for the VCSEL laser, and the electrical limiting layer is provided with a light-emitting hole for current and laser to pass through; the second Bragg reflector is positioned on one side, far away from the first Bragg reflector, of the active region; the second Bragg reflector is provided with a top surface and a bottom surface; the resistance layer is used for providing electrical obstruction for current entering the light-emitting unit; wherein the resistance values of the resistance layers of the two adjacent light-emitting units in the flowing direction of the current on the light-emitting array are R1 and R2 respectively, and R1 is larger than R2.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor technology, and in particular relates to a resistive VCSEL laser, a preparation method and a laser device. Background Art

[0002] VCSEL (Vertical-Cavity Surface-Emitting Laser) is a new type of semiconductor laser that emits laser light in a direction perpendicular to the substrate. It has the advantages of low threshold current, small size, and easy two-dimensional integration. In practical applications, it is usually necessary to integrate multiple VCSELs together to form a VCSEL array to improve output power and beam quality.

[0003] The VCSEL array is lit by inputting current into the VCSEL array. At present, when the VCSEL array is powered, it is usually powered from one side of the VCSEL array, but this power supply method causes the current to be high in the part close to the power supply, and the current is smaller on the side farther away from the power supply. The reduced current causes the corresponding VCSEL luminous power to decrease, which affects the uniformity of the light emitted by the VCSEL array. In order to improve the uniformity of the light emission of the VCSEL array, the VCSEL array is powered from both sides of the VCSEL array at the same time, but this method will cause the current entering the middle area of ​​the VCSEL array to be small, and the light emitted by the VCSEL array will be bright on both sides and dark in the middle.

[0004] In addition, both methods require complex circuit design and control, which increases the complexity and cost of the system. Therefore, it is necessary to propose a new VCSEL structure design scheme to improve the performance of VCSEL lasers.

[0005] Application Contents

[0006] One advantage of the present application is that a VCSEL laser is provided, in which, in order to balance the current, a gradient resistance layer is added, and the resistance of the light-emitting hole closer to the wire pad is larger. By adjusting the gradient ratio of the resistance, the current on each light-emitting hole is balanced, so that the laser emitted by each light-emitting unit remains uniform.

[0007] In order to achieve at least one of the above advantages or other advantages and purposes, according to one aspect of the present application, a resistive VCSEL laser is provided, wherein the resistive VCSEL laser comprises a plurality of light-emitting arrays, each of which comprises a plurality of light-emitting units arranged in sequence, wherein the light-emitting units comprise

[0008] a substrate layer having a top surface and a bottom surface;

[0009] a first Bragg reflector disposed on a top surface of the substrate layer;

[0010] an active region, located on a side of the first Bragg reflector away from the substrate layer;

[0011] An electrical confinement layer provides optical and electrical confinement for the VCSEL laser, and the electrical confinement layer has a light-emitting hole for current and laser to pass through;

[0012] A second Bragg reflector is located on a side of the active region away from the first Bragg reflector; the second Bragg reflector has a top surface and a bottom surface;

[0013] The resistance layer is used to provide electrical resistance to the current entering the light-emitting unit;

[0014] The resistance values ​​of the resistance layers of two adjacent light emitting units along the flow direction of the current on the light emitting array are R1 and R2 respectively, wherein R1>R2.

[0015] In the resistive VCSEL laser according to the present application, the light emitting unit further includes a first electrode as a cathode of the light emitting unit and a second electrode as an anode of the light emitting unit, and the resistive layer contacts a bottom surface of the second electrode.

[0016] In the resistive VCSEL laser according to the present application, the light emitting unit further includes an electrical conductor, and the resistive layer is located between the electrical conductor and the second electrode.

[0017] In the resistive VCSEL laser according to the present application, the resistance layer is a thin film resistance film.

[0018] In the resistive VCSEL laser according to the present application, the thickness L of the thin film resistor film is 0.1-1 μm.

[0019] In the resistive VCSEL laser according to the present application, the thin film resistor film material is a Si-based resistor film.

[0020] Another aspect of the present application provides a process for manufacturing a resistive VCSEL laser, which comprises the following steps:

[0021] S10. Forming an epitaxial main structure through an epitaxial growth process, wherein the epitaxial main structure sequentially includes a substrate layer, a first Bragg reflector, an active region, and a second Bragg reflector.

[0022] S20, presetting a pattern of a light-emitting array for the formed epitaxial main structure, and depositing a resistance film material on the top surface of the second Bragg reflector according to the preset light-emitting array pattern to form a resistance layer with a local resistance gradient;

[0023] S30, depositing a second electrode onto the top surface of the resistance layer;

[0024] S40, etching and depositing to form light-emitting units, each of which includes a substrate layer, a first Bragg reflector, an active area, a second Bragg reflector, and a resistance layer; wherein, on a preset light-emitting array, the resistance values ​​of the resistance layers of two adjacent light-emitting units along a current flow direction on the light-emitting array are R1 and R2, respectively, wherein R1>R2;

[0025] S50, defining the shape of the second electrode, and depositing a P-type ohmic contact electrode on the top surface of the second electrode to form a positive electrode electrically connected to the second electrode; and

[0026] S70, grinding and thinning the bottom of the substrate layer and then depositing a first electrode to form a negative electrode.

[0027] In the manufacturing process of the resistive VCSEL laser according to the present application, the electrical confinement layer is formed by oxidizing the high aluminum layer in the second Bragg reflector with water.

[0028] According to another aspect of the present application, the present application provides an electronic device, comprising:

[0029] A laser projection device for projecting laser light, wherein the laser projection device comprises any resistive VCSEL laser as described above;

[0030] a laser receiving device for receiving a laser signal; and

[0031] A processor is communicatively connected to the laser projection device and the laser receiving device.

[0032] Further objectives and advantages of the present application will be fully reflected through understanding of the following description and drawings.

[0033] These and other objects, features and advantages of the present application are fully reflected in the following detailed description, drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A top view of a resistive VCSEL laser where current is input from one side of the light-emitting array.

[0035] Figure 2 A top view of a resistive VCSEL laser with current input from both sides of the light-emitting array.

[0036] Figure 3 An example diagram of the light-emitting unit layer structure of a resistive VCSEL laser.

[0037] Figure 4 A cross-sectional view of the light-emitting unit of a resistive VCSEL laser.

[0038] Figure 5 FIG. 4 is an exemplary diagram of the light-emitting unit layer structure of another resistive VCSEL laser.

[0039] Figure 6 FIG. 4 is a cross-sectional view of a light-emitting unit of another resistive VCSEL laser. DETAILED DESCRIPTION

[0040] The terms and words used in the following specification and claims are not limited to the literal meanings, but are merely used by the applicant to enable a clear and consistent understanding of the present application. Therefore, it will be apparent to those skilled in the art that the following description of various embodiments of the present application is provided for illustration purposes only and not for the purpose of limiting the present application as defined by the appended claims and their equivalents.

[0041] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0042] Although ordinals such as "first," "second," and the like will be used to describe various components, those components are not limited herein. The term is used only 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 associated listed items.

[0043] The terms used herein are only used for the purpose of describing various embodiments and are not intended to be limiting. As used herein, singular forms are intended to include plural forms, unless the context clearly indicates an exception. It will also be understood that the terms "comprising" and / or "having" when used in this specification specify the presence of the described features, numbers, steps, operations, components, elements, or combinations thereof, without excluding the presence or addition of one or more other features, numbers, steps, operations, components, elements, or groups thereof.

[0044] Application Overview

[0045] When the pump source current enters the VCSEL laser array, there are two input methods: one is input from one end of the array, and the other is synchronous input from both ends. Regardless of single-end input or synchronous input from both ends, the current will be lost when flowing through each light-emitting unit 10. This causes the light-emitting unit 10 far away from the input end to receive a smaller current, so the light power it emits is lower; while the light-emitting unit 10 close to the input end receives a larger current, so the light power it emits is higher. This uneven current distribution phenomenon ultimately leads to uneven light emission from the VCSEL laser array.

[0046] Based on the above problem analysis, in order to solve the problem of uneven light emission in the VCSEL laser array and improve the optical power of the VCSEL laser array, the present application proposes to add a resistor layer 16 with a preset resistance value to each light emitting unit 10 to keep the current entering each light emitting unit 10 the same, so as to achieve uniform light emission and high optical power of the VCSEL laser array.

[0047] Accordingly, the present application proposes a resistive VCSEL laser, comprising a plurality of light-emitting arrays 1, each of the light-emitting arrays 1 comprising a plurality of light-emitting units 10 arranged in sequence, wherein the light-emitting unit 10 comprises a substrate layer 11 having a top surface and a bottom surface, a first Bragg reflector 12 located on the top surface of the substrate layer 11, an active region 13 located on a side of the first Bragg reflector 12 away from the substrate layer 11, an electrical confinement layer 14 providing optical and electrical confinement for the VCSEL laser, a second Bragg reflector 15 located on a side of the active region 13 away from the first Bragg reflector 12, and a resistance layer 16 for providing electrical obstruction to current entering the light-emitting unit 10; wherein the resistance values ​​of the resistance layer 16 of two adjacent light-emitting units 10 along the direction of current flow on the light-emitting array 1 are R1 and R2, respectively, wherein R1>R2.

[0048] After introducing the basic principles of the present application, various non-limiting embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0049] Schematic VCSEL laser

[0050] like Figure 1 As shown, the present application discloses a resistive vertical cavity surface emitting laser (VCSEL). The VCSEL laser is composed of a plurality of light-emitting arrays 1, which are arranged in an orderly manner in the horizontal or vertical direction. Each light-emitting array 1 further includes a plurality of light-emitting units 10. In the design, the current of the pump source is input from one end of the light-emitting array 1, and then each light-emitting unit 10 is lit in sequence.

[0051] In order to ensure that the luminous power of each light-emitting unit 10 remains consistent, a resistor is adapted on each light-emitting unit 10. The resistance R of these resistors gradually decreases in the direction in which the current moves along the light-emitting array 1, that is, resistor R1> resistor R2> resistor R3> resistor R4> resistor R5, and so on. This design not only ensures the uniformity of VCSEL laser light emission, but also improves its overall performance and stability.

[0052] Or as Figure 2 As shown, in other examples, in order to improve the luminous efficiency of the VCSEL laser, the current of the pump source is synchronously input from both ends of the light-emitting array 1, and each light-emitting unit 10 is adapted with a resistor, and the resistance R of these resistor layers gradually decreases in the direction of the current moving along the light-emitting array 1, that is, resistance R1>resistance R2>resistance R3>resistance R4.

[0053] See also Figure 3 and Figure 4 According to the VCSEL laser disclosed in the embodiment of the present application, the light-emitting unit 10 of the light-emitting array 1 on each VCSEL laser includes a substrate layer 11, a first Bragg reflector 12, an active area 13, an electrical confinement layer 14, and a second Bragg reflector 15 from bottom to top. The substrate layer 11 serves as the base of the light-emitting unit 10, and the first Bragg reflector 12 is superimposed on the upper surface of the substrate layer 11. The substrate layer 11 is an N-type doped gallium arsenide substrate, or in other embodiments, the substrate layer 11 is a P-type doped gallium arsenide substrate; of course, in other embodiments, the material of the substrate layer 11 can be a doped material such as InP, GaN, and GaAs. The substrate layer 11 has a top surface and a bottom surface, and a first electrode 19 is provided on the bottom surface of the substrate layer 11, and the first electrode 19 serves as the cathode of the light-emitting unit 10.

[0054] The first Bragg reflector 12 is grown and stacked on the top surface of the substrate layer 11 by vapor phase epitaxy (MOCVD) technology. The first Bragg reflector 12 is an N-DBR, and the N-DBR is formed by alternating stacking of N-type doped AlxGaAs with a high aluminum content and N-type doped AlxGaAs with a low aluminum content. It is worth mentioning that the material selection of the alternating layer depends on the operating wavelength of the laser emitted by the light emitting unit 10, and the optical thickness of the alternating layer is equal to or approximately equal to 1 / 4 of the operating wavelength of the laser.

[0055] The active region 13 is grown onto the top surface of the first Bragg reflector 12 by means of MOCVD technology. The active region 13 is sandwiched between the first Bragg reflector 12 and the second Bragg reflector 15 to form a resonant cavity. After being excited, photons are reflected back and forth in the resonant cavity and repeatedly amplified to form laser oscillation, thereby forming a laser.

[0056] The second Bragg reflector 15 is located above the first Bragg reflector 12. The second Bragg reflector 15 is grown to the top surface of the active area 13 by vapor phase epitaxy technology (MOCVD). The second Bragg reflector 15 is a P-DBR, and the P-DBR is formed by alternating stacks of multiple P-type doped AlxGaAs with high aluminum content and P-type doped AlxGaAs with low aluminum content.

[0057] A resistor layer 16 with a thickness L of 0.1-1 μm is stacked on the top surface of the second Bragg reflector 15, and the resistor layer 16 is connected in parallel with the ohmic electrode on the light emitting array 1. The resistor layer 16 blocks the current entering the active area 13, thereby controlling the amount of current entering the active area 13.

[0058] The resistor layer 16 is deposited on the top surface of the second Bragg reflector 15, and a second electrode 17 is stacked on the top surface of the resistor layer 16. The current on the ohmic electrode passes through the second electrode 17, the resistor layer 16 and the second Bragg reflector 15 in sequence and then enters the active area 13. The resistor layer 16 is made of a thin film resistor film, and the material of the thin film resistor film is a Si series resistor film; in this embodiment, the Si series resistor film is specifically a SiGe thin film material or a chromium silicon thin film.

[0059] refer to Figure 4 , each of the light-emitting units 10 is respectively equipped with a corresponding resistor layer 16, and the resistance value R of the resistor layer 16 is set according to the preset current value input to the light-emitting unit 10. The resistance values ​​R of adjacent resistor layers 16 gradually decrease along the direction of the current moving between the light-emitting units 10; that is, the resistance value R of the resistor equipped on the light-emitting unit 10 closer to the input end of the light-emitting array 1 is smaller, for example Figure 1 As shown, resistance R1>resistance R2>resistance R3, and so on.

[0060] For example, see Figure 5 and Figure 6 The position of the resistor layer 16 can be adjusted according to the process requirements. The resistor layer 16 is located on the upper surface of the second electrode 17. The ohmic contact electrode 20 is stacked on the upper surface of the resistor layer 16. The current on the ohmic electrode is input to the resistor layer 16, and then the current enters the second electrode 17 through the resistor layer 16. The resistor layer 16 uses a thin film resistor film, and the thin film resistor film material is one of Ni-Co series, Ta series, Si series, metal ceramic series resistor film, Au-Cr, and Ni-P.

[0061] In the embodiment of the present application, the side of the second Bragg reflector 15 away from the active area 13 is provided with an insulating protective layer, which protects the second Bragg reflector 15 from damage during operation and adjusts the laser emitted from the active area 13 to improve the divergence angle and optical power of the light emitting unit 10. In the embodiment of the present application, the protective layer is preferably made of Si with insulation and optical modulation properties. 3 N 4 In other modified embodiments, the protective layer may be SiO 2 , Al 2 O 3 , AlN. Or in another variant embodiment, the protective layer may be SiO 2 , Si 3 N 4 , Al 2 O 3 , various compositions in AlN.

[0062] The electrical confinement layer 14 is formed at the lower part of the second Bragg reflector 15 or at the upper part of the active area 13. The electrical confinement layer 14 has a relatively high resistivity to guide the charges from the middle area of ​​the VCSEL laser into the active area 13. The electrical confinement layer 14 is an annular structure, and the area enclosed by the electrical confinement layer 14 forms a light-emitting hole 141 for the laser in the active area 13 to emit. In the viewing direction from the second Bragg reflector 15 to the first Bragg reflector 12, the light-emitting hole 141 is a circular or hexagonal structure.

[0063] The electrical confinement layer 14 is formed by water oxidation of the second Bragg reflector 15 or the active region 13. Of course, in other embodiments, the electrical confinement layer 14 can also be formed by ion implantation into the second Bragg reflector 15 or the active region 13, wherein the implanted ions are one or more of the following ions: H+, O+, B+.

[0064] In summary, the VCSEL laser based on the embodiment of the present application is explained, and the VCSEL laser provides a feasible design scheme for uniform current passing through the light-emitting hole, which can change the current flow direction, reduce the current density at the edge of the light-emitting hole, and reduce the heat generated by the VCSEL laser when working, while improving the reliability of the VCSEL laser and improving the uniformity of the light spot emitted by the VCSEL laser when working, that is, forming a light spot with basically consistent brightness between the outer ring and the middle.

[0065] Schematic diagram of the method for preparing the resistive VCSEL laser

[0066] According to another aspect of the present application, a method for manufacturing a resistive VCSEL laser is also provided, which is used to prepare the VCSEL laser as described above. In an embodiment of the present application, the VCSEL laser can still use the traditional VCSEL preparation process during the preparation process. In this way, the original VCSEL production line and production equipment can be retained to be used to prepare the VCSEL laser of the present application, effectively reducing the production line modification cost of the VCSEL laser, thereby reducing the preparation cost of the VCSEL laser.

[0067] Specifically, in the embodiments of the present application, Figure 5 and Figure 6 As shown, the manufacturing method of the resistive VCSEL laser comprises the following steps:

[0068] S10. Form an epitaxial main structure through an epitaxial growth process, wherein the epitaxial main structure includes a substrate layer 11, a first Bragg reflector 12, an active area 13, and a second Bragg reflector 15; wherein the first Bragg reflector 12 is an N-type doped Bragg reflector, the second Bragg reflector 15 is a P-type doped Bragg reflector, and the active area 13 is located between the first Bragg reflector and the second Bragg reflector 15.

[0069] S20, for the formed epitaxial main structure, preset a pattern of the light emitting array 1, and deposit a resistance film material on the top surface of the second Bragg reflector 15 according to the preset pattern of the light emitting array 1 to form a resistance layer 16 with a local resistance gradient;

[0070] S30, depositing the second electrode 17 onto the top surface of the resistance layer 16;

[0071] S40, etching and depositing to form light-emitting units 10, each of the light-emitting units 10 comprising a substrate layer 11, a first Bragg reflector 12, an active region 13, a second Bragg reflector 15, and a resistor layer 16; wherein, on a preset light-emitting array 1, the resistance values ​​of the resistor layer 16 of two adjacent light-emitting units 10 along a current flow direction on the light-emitting array 1 are respectively R1 and R2, wherein R1>R2;

[0072] S50, defining the shape of the second electrode 17, and depositing a P-type ohmic contact electrode 20 on the top surface of the second electrode 17 to form a positive electrode electrically connected to the second electrode 17; and

[0073] S70 , grinding and thinning the bottom of the substrate layer 11 and then depositing a first electrode to form a negative electrode.

[0074] In step S40 , the electrical confinement layer 14 is formed by oxidizing the high aluminum layer in the second Bragg reflector 15 with water.

[0075] Schematic vehicle-mounted laser equipment

[0076] According to another aspect of the present application, a laser device is also provided. The working principle of the laser device is: using laser as a medium, emitting laser to the target to be measured, and receiving laser reflected by the target to be measured, 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), the relative position and distance between the target to be measured and the laser device are obtained, thereby realizing the detection, tracking and identification of the object to be measured in the target area.

[0077] It should be noted that in the apparatus and method of the present application, the components or steps in different embodiments can be decomposed and / or recombined without departing from the principles of the present application. Such decomposition and / or recombination should be considered to be included in the application concept of the present application.

[0078] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

Claims

1. A resistive VCSEL laser, characterized in that: The invention comprises a plurality of light-emitting arrays, each of which comprises a plurality of light-emitting units arranged in sequence, wherein the light-emitting units comprise a substrate layer having a top surface and a bottom surface; a first Bragg reflector disposed on a top surface of the substrate layer; an active region, located on a side of the first Bragg reflector away from the substrate layer; An electrical confinement layer provides optical and electrical confinement for the VCSEL laser, and the electrical confinement layer has a light-emitting hole for current and laser to pass through; A second Bragg reflector is located on a side of the active region away from the first Bragg reflector; the second Bragg reflector has a top surface and a bottom surface; The resistance layer is used to provide electrical resistance to the current entering the light-emitting unit; The resistance values ​​of the resistance layers of two adjacent light emitting units along the flow direction of the current on the light emitting array are R1 and R2 respectively, wherein R1>R2.

2. A resistive VCSEL laser according to claim 1, wherein: The light emitting unit further includes a first electrode and a second electrode, and the resistance layer contacts a bottom surface of the second electrode.

3. A resistive VCSEL laser according to claim 1, wherein: The first Bragg reflector is an N-DBR, and the second Bragg reflector is a P-DBR.

4. A resistive VCSEL laser according to claim 1, wherein: The resistance layer is a thin film resistance film.

5. A resistive VCSEL laser according to claim 4, wherein: The thickness L of the thin film resistor film is 0.1-1 μm.

6. A resistive VCSEL laser according to claim 4, wherein: The thin film resistor film material is a Si series resistor film.

7. A process for manufacturing a resistive VCSEL laser as claimed in claims 1 to 6, wherein: The following steps are involved: S10. Forming an epitaxial main structure through an epitaxial growth process, wherein the epitaxial main structure sequentially includes a substrate layer, a first Bragg reflector, an active region, and a second Bragg reflector. S20, for the formed epitaxial main structure, preset a pattern of the light-emitting array, and deposit a resistance film material on the top surface of the second Bragg reflector according to the preset light-emitting array pattern to form a resistance layer with a local resistance gradient; S30, deposit a second electrode on the top surface of the resistance layer; S40, etching and depositing to form light-emitting units, each of which includes a substrate layer, a first Bragg reflector, an active area, a second Bragg reflector, and a resistance layer; wherein, on a preset light-emitting array, the resistance values ​​of the resistance layers of two adjacent light-emitting units along a current flow direction on the light-emitting array are R1 and R2, respectively, wherein R1>R2; S50, defining the shape of the second electrode, and depositing a P-type ohmic contact electrode on the top surface of the second electrode to form a positive electrode electrically connected to the second electrode; and S70, grinding and thinning the bottom of the substrate layer and then depositing a first electrode to form a negative electrode.

8. A process for manufacturing a resistive VCSEL laser according to claim 7, wherein: The electrical confinement layer is formed by oxidizing the high aluminum layer in the second Bragg reflector with water.

9. An electronic device, characterized in that: include: A laser projection device for projecting laser light, wherein the laser projection device comprises any resistive VCSEL laser according to any one of claims 1 to 9; a laser receiving device for receiving a laser signal; and A processor is communicatively connected to the laser projection device and the laser receiving device.

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