Vertical cavity surface emitting laser, array and preparation method thereof

Abstract

The present invention provides a vertical cavity surface emitting laser, an array and a preparation method thereof, which relate to the technical field of semiconductor lasers and can solve the problem of stress defects caused by oxidation to generate a current limiting layer. The vertical cavity surface emitting laser comprises: a substrate, an N-type Bragg reflection layer, an active area and a P-type Bragg reflection layer stacked in sequence. Among them, a current limiting layer grown under a first temperature condition is arranged on a side of the P-type Bragg reflection layer close to the active area or in the P-type area of ​​the active area. The first temperature is lower than the second temperature for growing the P-type Bragg reflection layer or the N-type Bragg reflection layer, the current limiting layer is a non-oxidized semi-insulating material, and a current injection area is arranged in a local area of ​​the current limiting layer. The vertical cavity surface emitting laser of the present invention can maintain the continuity of the material of the current limiting layer and the material of the Bragg reflection layer, thereby improving the reliability of the vertical cavity surface emitting laser.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor lasers, and in particular to a vertical cavity surface emitting laser, an array and a preparation method thereof. Background Art

[0002] Vertical-Cavity Surface-Emitting Laser (VCSEL) is a semiconductor laser with a special structure and function, which is characterized by the laser being emitted perpendicular to the top surface. VCSEL is widely used in optical communications, data centers, 3D sensing, autonomous driving, consumer electronics and other fields.

[0003] In order to achieve current limitation, VCSELs are mainly classified into ion implantation type and oxidation limitation type. Ion implantation type VCSELs produce lattice damage and defects in the implantation area, and it is not easy to accurately control the size of the current injection area. When preparing the oxidation limitation layer of the oxidation limitation type VCSEL, AlGaAs with a high Al content is converted into Al2O3, and the volume reduction will cause mismatch, and the introduced stress is likely to cause various defects, thus bringing a series of reliability problems. Summary of the invention

[0004] In view of the above problems, embodiments of the present invention provide a vertical cavity surface emitting laser, an array and a method for manufacturing the same.

[0005] One aspect of the present invention provides a vertical cavity surface emitting laser, comprising: a substrate, an N-type Bragg reflector, an active region and a P-type Bragg reflector stacked in sequence. A current limiting layer grown under a first temperature condition is provided on a side of the P-type Bragg reflector close to the active region or in a P-type region of the active region. And / or a current limiting layer grown under a first temperature condition is provided on a side of the N-type Bragg reflector close to the active region or in an N-type region of the active region. The first temperature is less than a second temperature for growing the P-type Bragg reflector or the N-type Bragg reflector, the current limiting layer is a non-oxidized semi-insulating material, and a local region of the current limiting layer is provided with a current injection region.

[0006] According to an embodiment of the present invention, the material of the current limiting layer is Al x Ga 1-x As, 0≤x≤1, and the thickness of the current confinement layer is less than or equal to one quarter of the optical wavelength.

[0007] According to an embodiment of the present invention, the current confinement layer is a single layer or multiple layers arranged in pairs, wherein when the current confinement layer is multiple layers, the aluminum components of adjacent current confinement layers are different, and the thickness of each current confinement layer is equal to a quarter of the optical wavelength.

[0008] According to an embodiment of the present invention, the current injection region is doped with magnesium or zinc ions, and the diameter of the current injection region is 1 μm to 50 μm.

[0009] According to an embodiment of the present invention, one or more oxide layers are provided on the side of the current limiting layer away from the active area. In the oxide layer, an oxide hole is provided in the area corresponding to the current injection area, and the size of the oxide hole is larger than the size of the current injection area. And in the case of providing multiple oxide layers, the size of each oxide hole remains unchanged or increases as the distance from the current limiting layer increases.

[0010] According to an embodiment of the present invention, an ion implantation region is provided on a side of the current limiting layer away from the active region. The implanted ions in the ion implantation region include: + , O + 、N + and F + .

[0011] According to an embodiment of the present invention, there are one or more active regions. Wherein, in the case of multiple active regions, tunnel junctions are arranged between adjacent active regions.

[0012] According to an embodiment of the present invention, the vertical cavity surface emitting laser further comprises at least one of the following: a P electrode and an N electrode. A lens. The P electrode and the N electrode are arranged on the same side or different sides of the active region, and the P electrode is provided with a light-transmitting region for emitting laser light. The lens is arranged in the light-transmitting region.

[0013] Another aspect of the present invention provides a vertical cavity surface emitting laser array, comprising a plurality of vertical cavity surface emitting lasers according to any embodiment of the present disclosure, wherein the vertical cavity surface emitting laser array is a 1D or 2D addressable laser array.

[0014] Another aspect of the present invention provides a method for preparing a vertical cavity surface emitting laser, comprising: growing an N-type Bragg reflection layer, an active area, and a preset number of AlGaAs layers on a substrate in sequence under a second temperature condition. Cooling to a first temperature, and growing a current limiting layer on the preset number of AlGaAs layers, the first temperature range being 200°C to 430°C. Annealing the current limiting layer, and doping a local area of ​​the annealed current limiting layer to form a current injection area. And heating to a second temperature, and completing the growth of a P-type Bragg reflection layer on the locally doped current limiting layer.

[0015] According to an embodiment of the present invention, a current limiting layer that plays a current limiting role can be generated by low-temperature growth of a current limiting layer, while also maintaining the continuity of the material of the current limiting layer and the material of the Bragg reflection layer. Therefore, the technical problem of stress defects caused by oxidation-generated current limiting layers is at least partially overcome, thereby achieving the technical effect of improving the reliability of vertical cavity surface emitting lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above contents and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0017] Figure 1 A schematic diagram of the structure of a vertical cavity surface emitting laser according to an embodiment of the present invention is shown;

[0018] Figure 2 A schematic diagram of a structure of a vertical cavity surface emitting laser according to another embodiment of the present invention is shown;

[0019] Figure 3 A schematic diagram shows a structure of a vertical cavity surface emitting laser provided with an oxide layer according to an embodiment of the present invention;

[0020] Figure 4 A schematic diagram shows a structure of a vertical cavity surface emitting laser provided with an ion implantation region according to an embodiment of the present invention;

[0021] Figure 5 A schematic diagram shows a structure of a vertical cavity surface emitting laser provided with multiple active regions according to an embodiment of the present invention;

[0022] Figure 6 The flowchart of the method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention is schematically shown.

[0023] [Description of Reference Numerals]

[0024] 1-substrate; 2-N-type Bragg reflection layer; 3-active area; 4-P-type Bragg reflection layer; 5-current limiting layer; 51-current injection area; 6-oxide layer; 7-ion implantation area; 8-tunnel junction; 9-P electrode; 10-N electrode. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0026] It should be noted that in the drawings or descriptions, similar or identical parts use the same figure numbers. The technical features in the various embodiments exemplified in the specification can be freely combined to form new solutions without conflict, and in the drawings, the shape or thickness of the embodiments can be expanded and simplified or conveniently indicated. Furthermore, the elements or implementations not shown or described in the drawings are in a form known to ordinary technicians in the relevant technical field. In addition, although demonstrations of parameters containing specific values ​​may be provided herein, it should be understood that the parameters do not need to be exactly equal to the corresponding values, but can be approximated to the corresponding values ​​within an acceptable error tolerance or design constraint.

[0027] Unless there are technical obstacles or contradictions, the above-mentioned various embodiments of the present invention can be freely combined to form other embodiments, and these other embodiments are all within the protection scope of the present invention.

[0028] Although the present invention is described in conjunction with the accompanying drawings, the embodiments disclosed in the drawings are intended to exemplify the preferred embodiments of the present invention and should not be construed as limiting the present invention. The size ratios in the drawings are merely illustrative and should not be construed as limiting the present invention.

[0029] Although some embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present general disclosed concept.

[0030] Figure 1 The structure of a vertical cavity surface emitting laser according to an embodiment of the present invention is schematically shown.

[0031] According to an embodiment of the present invention, Figure 1 As shown, the present invention provides a vertical cavity surface emitting laser, comprising: a substrate 1, an N-type Bragg reflection layer 2, an active area 3 and a P-type Bragg reflection layer 4 stacked in sequence. Among them, a current limiting layer 5 grown under a first temperature condition is arranged on a side of the P-type Bragg reflection layer 4 close to the active area 3 or in a P-type region of the active area 3. And / or a current limiting layer 5 grown under a first temperature condition is arranged on a side of the N-type Bragg reflection layer 2 close to the active area 3 or in an N-type region of the active area 3. The first temperature is lower than a second temperature for growing the P-type Bragg reflection layer 4 or the N-type Bragg reflection layer 2, the current limiting layer 5 is a non-oxidized semi-insulating material, and a local area of ​​the current limiting layer 5 is provided with a current injection region 51.

[0032] In some embodiments, a vertical cavity surface emitting laser has the following structures from bottom to top:

[0033] The substrate, as the basic supporting structure of the laser, provides good crystal quality and thermal stability. The substrate can be, for example, a GaAs substrate or a Si substrate.

[0034] It should be noted that when a Si substrate is used, a buffer layer can be inserted between the substrate and the N-type DBR to reduce or eliminate stress or defects introduced by mismatch.

[0035] The N-type Bragg reflector is grown on a GaAs substrate through a specific process and is used to improve the reflection efficiency of light in the laser and enhance the light output.

[0036] The active region, located above the N-type Bragg reflector, is the core region for generating laser light and includes necessary doping and structural design. The active region includes the quantum well and the P-type and N-type regions on both sides. The active region is, for example, an InGaAs / AlGaAs quantum well active region.

[0037] The P-type Bragg reflector layer, above the active area, is also used to improve the light reflectivity. For example, N-type and P-type DBR (Distributed Bragg Reflector) are made of Al with different Al compositions. y Ga 1-y As / Al z Ga 1-z As is grown alternately, and the thickness of each layer is consistent with 1 / 4 optical wavelength. In addition, N-type DBR must have a very high reflectivity, generally above 99.9%. The reflectivity of P-type DBR is lower than that of N-type DBR.

[0038] Among them, a layer of non-oxidized semi-insulating material is grown as a current limiting layer on the side of the P-type Bragg reflector layer close to the active area, for example, in the P-type area of ​​the active area, or in the alternating high refractive index layer and low refractive index layer separated from the active area by, for example, 1 to 2 cycles (tending to be close to the active area but not damaging the active area). The current limiting layer is grown under a first temperature condition, the temperature is lower than the growth temperature (second temperature) of the P-type Bragg reflector layer. And in a local area of ​​the current limiting layer, the injection area is transformed into a conductive material by diffusion, ion implantation or other doping methods to form a current injection area for the active area, allowing current to be injected into the active area through the area, thereby stimulating laser generation.

[0039] By introducing the current limiting layer, the distribution of current in the laser is effectively limited, improving the efficiency and stability of the laser. At the same time, the local current injection area ensures that the current can be accurately and efficiently injected into the active area, further improving the performance of the laser.

[0040] In some embodiments, similar to the above embodiments, a layer of non-oxidized semi-insulating material is grown on the side of the N-type Bragg reflector layer close to the active region as a current limiting layer. The current limiting layer is also grown under the first temperature condition and has a current injection region.

[0041] The introduction of the N-type current limiting layer not only limits the current distribution in the N-type region, but also guides the current to enter the active region efficiently through the precisely designed current injection region. This design is suitable for scenarios with special requirements for current control in the N-type region, such as when the current distribution in the N-type region needs to be optimized to improve laser performance.

[0042] By introducing a current limiting layer in the N-type region, precise control of the current in the N-type region is achieved, further improving the overall performance of the laser. At the same time, the local current injection area ensures efficient injection of current, allowing the laser to maintain high efficiency while having better stability and reliability.

[0043] The above two embodiments respectively demonstrate the specific design schemes of introducing a current limiting layer on the side of the P-type Bragg reflector layer and the N-type Bragg reflector layer near the active area. By precisely controlling the growth temperature of the current limiting layer and locally setting the current injection area, the optimization control of the current distribution inside the laser is achieved, thereby improving the performance and stability of the laser. Both design schemes are suitable for the manufacture and optimization of vertical cavity surface emitting lasers, and can be selected and optimized according to specific application scenarios and requirements.

[0044] According to an embodiment of the present invention, the material of the current limiting layer is Al x Ga 1-x As, 0≤x≤1, and the thickness of the current confinement layer is less than or equal to one quarter of the optical wavelength.

[0045] In some embodiments, the vertical cavity surface emitting laser design structure of this embodiment is composed of the following parts:

[0046] GaAs substrate or Si substrate, as the base of the laser, provides a stable crystal structure.

[0047] N-type distributed Bragg reflector (DBR) consists of multiple layers of Al with different Al compositions. y Ga 1-y As / Al z Ga 1-z As is grown alternately, where 0≤y≤1, 0≤z≤1, and the values ​​of y and z are adjusted according to the reflectivity requirements of the DBR. In order to obtain a higher reflectivity with the least number of pairs, it is generally required that the two layers have as large a refractive index difference as possible, for example, the y value can be 0.1 and the z value can be 0.9. This design can effectively improve the reflection efficiency of the laser in the vertical direction and enhance the performance of the laser.

[0048] The active region, located on the N-type DBR, is the core area for generating laser light. The specific design of the active region (such as doping concentration, thickness, etc.) depends on the target wavelength and output power of the laser.

[0049] P-type distributed Bragg reflector (DBR), similar to N-type DBR, but located above the active region, is used to reflect light propagating downward from above.

[0050] Among them, the material of the current limiting layer is Al x Ga 1-x As, where 0≤x≤1. This material has good semiconductor properties and good lattice matching with the GaAs substrate and DBR layer, which can ensure the stability and reliability of the laser.

[0051] The current confinement layer is grown at a lower temperature than that of the P-type or N-type DBR. Low temperature growth helps to form high-quality semi-insulating thin film materials with fewer defects and impurities.

[0052] After the current limiting layer is grown, annealing is performed. This step can further improve the performance of the material and form a non-conductive semi-insulating GaAs or AlGaAs thin film material. This material has high mobility, short carrier recombination lifetime and stable performance, which helps to improve the efficiency and reliability of the laser.

[0053] The thickness of the current confinement layer is precisely controlled to be less than or equal to a quarter of the optical wavelength. This thickness design ensures that the current confinement layer has minimal impact on the transmission of the laser while effectively limiting the distribution of the current.

[0054] It is understandable that when the thickness of the current limiting layer is less than a quarter of the optical wavelength, it is necessary to continue to grow a high refractive index layer or a low refractive index layer with the same or similar composition at a second temperature, but the thickness of the two grown layers should be superimposed to a quarter of the optical wavelength. That is, the current limiting layer is obtained by cooling down and growing a certain layer or a part of the alternating high refractive index layer and low refractive index layer (basic layer structure of DBR).

[0055] In local areas of the current limiting layer, current injection areas are set by doping process. These areas allow current to pass through and be injected into the active area, thereby stimulating laser generation. The location and size of the current injection area can be optimized according to the specific needs of the laser.

[0056] The vertical cavity surface emitting laser of this embodiment introduces Al x Ga 1-xThe current limiting layer of As material is grown and annealed under low temperature conditions to achieve optimized control of the current distribution inside the laser. This design not only improves the efficiency and stability of the laser, but also further improves the performance of the laser by precisely controlling the thickness of the current limiting layer and setting the current injection area. In addition, due to the use of materials with good lattice matching with the substrate and DBR layer, the laser also has high reliability and stability, and is suitable for various optoelectronic and optical communication applications.

[0057] Figure 2 The structure of a vertical cavity surface emitting laser according to another embodiment of the present invention is schematically shown.

[0058] According to an embodiment of the present invention, Figure 2 As shown, the current confinement layer 5 is a single layer or multiple layers arranged in pairs. Wherein, in the case where the current confinement layer 5 is multiple layers, the aluminum components of adjacent current confinement layers 5 are different, and the thickness of each current confinement layer 5 is equal to a quarter of the optical wavelength.

[0059] In some embodiments, the vertical cavity surface emitting laser design in this embodiment is based on the above embodiment, and the current confinement layer is optimized in more detail. The overall structure of the laser still includes key parts such as substrate, N-type distributed Bragg reflector (DBR), active region, and P-type distributed Bragg reflector (DBR).

[0060] In some applications, a single current confinement layer can be used. This layer is made of Al x Ga 1-x As material, where 0≤x≤1, and the specific value of x is precisely selected according to the performance requirements of the laser. The thickness of the single-layer current limiting layer is less than or equal to a quarter of the optical wavelength, which can ensure effective current limitation and minimal impact on laser transmission.

[0061] In applications where more precise control of current distribution is required, adjacent multi-layer current confinement layers arranged in pairs may be used, with the number of pairs of inserted paired Bragg reflection layers being ≥ 1. Adjacent layers in these multi-layer current confinement layers are composed of Al with different aluminum compositions. x Ga 1-x For example, the first layer may have a lower x value (i.e., a lower aluminum content) while the second layer has a higher x value (i.e., a higher aluminum content).

[0062] The thickness of each current limiting layer is equal to one quarter of the optical wavelength. This design allows for finer control of the current distribution by adjusting the aluminum composition and thickness of different layers. By optimizing these parameters, the performance of the laser can be further improved. For example, by thickening the thickness of the current limiting layer, the device reliability is not affected, and the capacitance of the VCSEL can be further reduced, because the increase in thickness does not introduce additional mismatch stress.

[0063] In the local area of ​​the current limiting layer, current injection areas are set by doping process. These areas allow current to pass through and be injected into the active area, thereby stimulating laser generation. The location and size of the current injection area are optimized according to the specific needs of the laser.

[0064] The vertical cavity surface emitting laser in this embodiment achieves precise control of the current distribution inside the laser by introducing a single layer or adjacent multi-layer current limiting layer design. This design not only improves the efficiency and stability of the laser, but also further optimizes the performance of the laser by adjusting the aluminum composition and thickness of different layers. The design of multi-layer current limiting layers provides greater flexibility and possibilities for improving the performance of the laser, and is suitable for a variety of high-performance, high-precision optoelectronic and optical communication applications.

[0065] According to an embodiment of the present invention, the current injection region is doped with magnesium or zinc ions, and the diameter of the current injection region is 1 μm to 50 μm.

[0066] In some embodiments, the vertical cavity surface emitting laser (VCSEL) is mainly composed of a substrate, an N-type Bragg reflector (DBR), an active region, a P-type Bragg reflector (DBR), etc. Among them, the current limiting layer, as one of the key structures, is located between the P-type or N-type DBR and the active region, and is used to accurately control the distribution of the current, thereby improving the performance of the laser.

[0067] The current limiting layer can be a single layer structure or a plurality of adjacent Al2O3 layers with different aluminum compositions. x Ga 1-x As (0≤x≤1) layers. The thickness of each layer is designed to be a quarter of the optical wavelength to ensure the transmission efficiency of light between layers. The material of the current limiting layer is grown at low temperature and annealed to form a non-conductive semi-insulating GaAs or AlGaAs thin film material, which has high mobility, short carrier recombination lifetime and stable performance.

[0068] The current injection region is created by doping with magnesium (Mg) or zinc (Zn) ions. These ions can effectively control the conductivity of this region, thereby precisely guiding the current through and injecting it into the active region.

[0069] The diameter of the current injection region is designed to be, for example, between 1 μm and 50 μm. The selection of this range is based on the performance requirements of the laser in practical applications. A smaller diameter can achieve more precise current control and is suitable for the preparation of high-speed VCSELs, applications requiring high-precision processing or high-resolution imaging; while a larger diameter is suitable for applications requiring higher output power.

[0070] It should be noted that it is difficult to make a small-size, i.e., a small-diameter current injection region for an oxidation-limited VCSEL, especially when the diameter of the oxidation hole is less than 5 microns. The method of the present invention can easily make a small-diameter current injection region, thereby obtaining a VCSEL with a higher bandwidth.

[0071] The vertical cavity surface emitting laser in this embodiment achieves precise control of the current distribution inside the laser by precisely designing the current limiting layer and the current injection area. The current limiting layer uses a semi-insulating GaAs thin film material grown at low temperature and annealed to ensure high mobility, short carrier recombination lifetime and stable performance. The current injection area achieves precise guidance and injection of current by doping magnesium or zinc ions and controlling its diameter range. This design not only improves the efficiency and stability of the laser, but also provides strong support for various high-performance, high-precision optoelectronic and optical communication applications.

[0072] Figure 3 The structure of a vertical cavity surface emitting laser provided with an oxide layer according to an embodiment of the present invention is schematically shown.

[0073] According to an embodiment of the present invention, Figure 3 As shown, one or more oxide layers 6 are provided on the side of the current limiting layer 5 away from the active area 3. Oxide holes are provided in the area corresponding to the current injection area 51 in the oxide layer 6, and the size of the oxide holes is larger than the size of the current injection area 51. And in the case where multiple oxide layers 6 are provided, the size of each oxide hole remains unchanged or increases as the distance from the current limiting layer 5 increases.

[0074] In some embodiments, a vertical cavity surface emitting laser (VCSEL) reduces the capacitance of the device by providing an oxide layer on the side of the current limiting layer away from the active region and providing an oxide aperture (also called an oxide ring, in English) in the oxide layer, thereby improving the bandwidth of the VCSEL. The following is a detailed example:

[0075] One or more oxide layers may be provided. For example, a three-layer oxide layer design is adopted, with the first layer close to the current limiting layer, the second layer located above the first layer, and the third layer located above the second layer. The oxide layer is, for example, composed of aluminum oxide (Al2O3) formed by oxidation of AlGaAs, which has good insulation properties, helps to reduce capacitance, and also plays a role in limiting current and light field.

[0076] The oxide holes are located in the oxide layer and correspond to the current injection areas. These channels allow current to be injected from the outside into the active area. The size of the oxide holes is larger than the size of the current injection area to ensure that the current can be injected smoothly. For example, the diameter of the current injection area is designed to be 5μm, while the diameter of the oxide holes may be 7μm or larger.

[0077] Generally, a multi-layer oxide layer is used. In the case where a multi-layer oxide layer is provided, the size of each oxide hole may increase as the distance from the current limiting layer increases. For example, the diameter of the oxide hole in the first oxide layer is 7 μm, the diameter of the oxide hole in the second oxide layer may increase to 9 μm, and the diameter of the oxide hole in the third oxide layer may increase to 11 μm.

[0078] It should be noted that the diameters of the oxidation holes in the above three oxidation layers are 7 μm, 9 μm and 11 μm respectively, which is just an example. In fact, the diameters of the oxidation holes in the three layers can also be the same, for example, 9 μm. It is also possible to use 4 layers of the same composition and the same diameter, and there are also several layers with larger diameters added on top, forming a step-like shape from top to bottom. The introduced oxidation layer 6 mainly plays the role of reducing capacitance.

[0079] By precisely designing the size and position of the oxide holes, the current distribution can be precisely controlled, thereby improving the efficiency and stability of the laser. This design has good scalability and can adjust the number of oxide layers and the size of the oxide holes according to specific needs.

[0080] It is understandable that the oxide layer is obtained by, for example, oxidizing the DBR layer. In the case of multiple oxide layers, the higher the Al component, the deeper the oxidation. By oxidizing different DBR layers at different depths, oxide holes of different sizes can be obtained.

[0081] By introducing an oxide layer, especially on the side of the current limiting layer away from the active area, the capacitance between the current limiting layer and the active area can be effectively isolated, thereby reducing the capacitance of the entire device. This helps to reduce signal loss and improve the performance of the laser. Due to the reduction in capacitance, the response time of the VCSEL will be faster, thereby increasing its bandwidth. This means that the laser can respond to changes in external signals more quickly, achieving higher data transmission rates and lower bit error rates. By reducing capacitance and increasing bandwidth, this design can significantly improve the performance of VCSELs and meet the needs of various high-performance, high-precision optoelectronics and optical communication applications. On the other hand, these oxide layers are a certain distance from the light-emitting area and have little effect on reliability-related issues.

[0082] Figure 4 The structure of a vertical cavity surface emitting laser provided with an ion implantation region according to an embodiment of the present invention is schematically shown.

[0083] According to an embodiment of the present invention, Figure 4 As shown in FIG. 1 , an ion implantation region 7 is provided on one side of the current limiting layer 5 away from the active region 3. The implanted ions in the ion implantation region 7 include: + , O + 、N + and F + .

[0084] In some embodiments, in the design of a vertical cavity surface emitting laser (VCSEL), in order to further reduce the capacitance of the device and increase the bandwidth, an ion implantation region may be provided on the side of the current limiting layer away from the active region. The following are specific design examples and principle descriptions:

[0085] The ion implantation region is arranged on the side of the current limiting layer away from the active region. Such a layout can effectively control the distribution of the electric field and help reduce the capacitance of the device.

[0086] In the ion implantation area, one or more ions such as H+, O+, N+ and F+ are selected for implantation, and H+ ions are commonly used. These ions have different electrical properties in semiconductor materials, and the electric field and capacitance can be finely controlled by precisely controlling the implantation conditions and distribution.

[0087] The ion implantation energy can be adjusted according to the specific material and design requirements. For example, for H+ ions, the implantation energy may be set between 300keV and 420keV to form a suitable charge distribution. The implantation dose is also a key factor affecting device performance. By optimizing the implantation dose, precise control of the electric field distribution and capacitance can be achieved.

[0088] By setting an ion implantation area on the side of the current limiting layer away from the active area and implanting specific ions, a layer of area with specific electrical characteristics can be formed. This layer can effectively reduce the capacitance of the device. Reducing the capacitance means that the response time of the device will be faster, so the bandwidth of the VCSEL can be increased. This enables the VCSEL to respond to changes in external signals more quickly, thereby achieving higher data transmission rates and lower bit error rates.

[0089] By setting an ion implantation area on the side of the current limiting layer away from the active area and injecting H+, O+, N+ and F+ plasma, the capacitance of the VCSEL can be effectively reduced and the bandwidth can be increased. This design not only improves the performance of the laser, but also provides more possibilities for its application in optoelectronics and optical communications. At the same time, by precisely controlling the implantation parameters and the distribution of ions, the performance of the device can be further optimized to meet the needs of different application scenarios.

[0090] Figure 5 The structure of a vertical cavity surface emitting laser provided with multiple active regions according to an embodiment of the present invention is schematically shown.

[0091] According to an embodiment of the present invention, Figure 5 As shown, there are one or more active regions 3. In the case of multiple active regions 3, tunnel junctions 8 are arranged between adjacent active regions 3.

[0092] In some embodiments, when a VCSEL (vertical cavity surface emitting laser) design includes one or more active regions, especially when there are multiple active regions, a tunnel junction is usually set between adjacent active regions. The following is a detailed example of such a design:

[0093] In VCSELs, multiple active regions may be designed to increase output power. These active regions can be single or stacked, depending on the design requirements.

[0094] For example, a VCSEL containing 2-5 (eg, 3) active regions can be designed, and each active region is connected via a tunnel junction.

[0095] The tunnel junction is a special structure that allows carriers (electrons or holes) to tunnel from one active region to another without overcoming a large energy barrier. Through the design of the tunnel junction, electrical coupling between adjacent active regions can be achieved, so that optical signals from different active regions can be superimposed, thereby increasing the total output power.

[0096] The thickness, doping concentration and material selection of the tunnel junction are all key factors affecting the tunneling efficiency. For example, the material of the tunnel junction (PN junction) can be GaAs / AlGaAs, and the thickness is, for example, 15-30 nm.

[0097] For example, in order to obtain a higher tunneling probability, the tunnel junction should use semiconductor materials with a direct bandgap structure and minimize the bandgap and electron effective mass. At the same time, increasing the doping concentration on both sides of the tunnel junction can reduce the thickness of the tunnel barrier and further improve the tunneling efficiency.

[0098] The design of the tunnel junction needs to comprehensively consider factors such as material selection, thickness, doping concentration, etc. to achieve a high tunneling efficiency. By optimizing the design of the tunnel junction, the overall performance of the laser can be improved, including output power, bandwidth, and response speed.

[0099] It is understandable that current limiting layers may be added on both sides of the tunnel junction to further optimize the current distribution.

[0100] By designing multiple active regions in a VCSEL and connecting them using tunnel junctions, the output power of the laser can be significantly increased. This design is very beneficial for application scenarios that require high power output, such as autonomous driving, lidar and other application fields.

[0101] In addition to the layer structure of the above-mentioned embodiment, the vertical cavity surface emitting laser may, for example, further include a light storage layer between the N-type Bragg reflection layer and the active area that can reduce the divergence angle, and the light storage layer may or may not have an anti-reflection layer near the active area to facilitate better light storage in the light storage layer and further reduce the divergence angle.

[0102] In addition, for multi-junction VCSELs, an ion implantation region or an oxide layer can be added near the active region of the DBR to further optimize the confinement of the current and light field.

[0103] According to an embodiment of the present invention, Figure 1 As shown, the vertical cavity surface emitting laser further includes at least one of the following: a P electrode 9 and an N electrode 10. A lens. The P electrode 9 and the N electrode 10 are arranged on the same side or different sides of the active region, and the P electrode 9 is provided with a light-transmitting region for emitting laser light. The lens is arranged in the light-transmitting region.

[0104] In some embodiments, in the VCSEL, the P electrode and the N electrode are arranged on different sides of the active region. A light-transmitting region is arranged on the P electrode, and this region allows the laser to be emitted directly from the front side of the VCSEL.

[0105] For example, in a VCSEL design, the P electrode and N electrode are located on different sides of the active region. When current passes through, photons are generated in the active region, which are then emitted through the light-transmitting area of ​​the P electrode (usually an area not covered by metal). Since the P electrode is located on the front side of the chip, the light is emitted from the front side of the chip. For example, there is a light-transmitting area with a diameter of several microns in the center of the P electrode, and the laser is emitted vertically from this area.

[0106] In order to optimize the beam characteristics, a microlens with a diameter of hundreds of microns can be integrated above the light-passing area to focus and compress the divergence angle of the beam.

[0107] Unlike front-emitting VCSELs, the P-electrode and N-electrode of back-emitting VCSELs are set on the same side of the active area. The laser is emitted from the back of the VCSEL, which usually requires a specific substrate or reflective structure to achieve. For example, the light is emitted from the GaAs substrate by adjusting the reflectivity of the N-type DBR (also called the lower DBR) to be less than the reflectivity of the P-type DBR (upper DBR).

[0108] In the design of back-emitting VCSEL, the P electrode and the N electrode are both located at the bottom of the VCSEL, for example. In order to make the laser emit from the back, a layer of relatively low reflectivity material can be designed under the substrate to reflect the laser to the back. The N electrode (or P electrode, depending on the specific design) covers most of the bottom area, while the P electrode (or N electrode) occupies a smaller area as a light-passing area. The light is emitted from the back of the chip through this light-passing area. One advantage of back-emitting VCSELs is that they are better compatible with silicon-based optoelectronic integrated circuits because light can be emitted from the bottom of the chip (the side that contacts the silicon-based electronic devices).

[0109] It should be noted that the situation of emitting light from the GaAs substrate is not applicable to VCSELs with a wavelength of 850 nm, because the absorption edge of GaAs is near 870 nm and it absorbs light with a wavelength of 850 nm. However, VCSELs with wavelengths such as 905 nm and 940 nm can be designed to emit light from the GaAs substrate.

[0110] Similarly, microlenses or other optical elements can be integrated on the back side to improve the beam quality.

[0111] Whether front-emitting or back-emitting, VCSELs can be integrated with lenses to improve beam focusing and coupling efficiency. The lenses can be integrated directly above or below the light-passing area, or implemented through external optical systems.

[0112] Lens-integrated VCSELs incorporate a lens to enhance the directionality and efficiency of the light output. This design can be implemented on either front-emitting or back-emitting VCSELs. Lenses are typically made by adding one or more layers of transparent material (such as glass or plastic) above or around the light-passing area, with a specific shape (such as hemispherical or parabolic) to focus or collimate the light output.

[0113] In front-emitting VCSELs, a lens can be integrated above the light-passing area of ​​the P electrode to focus the light into a smaller angle range, thereby improving the efficiency of light coupling into optical fibers or other optical components. In back-emitting VCSELs, a lens can be integrated at the bottom of the chip or used as an external component in conjunction with the chip to enhance the directionality of light emitted from the back.

[0114] For example, in a VCSEL design integrated with a lens, a microlens is fabricated directly above the light-passing area on the P electrode. The diameter and curvature of this microlens are optimized to match the beam characteristics of the VCSEL and the requirements of the target application. With this integration, laser light can be emitted directly from the VCSEL and focused to the target location without the need for an additional optical system.

[0115] Vertical Cavity Surface Emitting Lasers (VCSELs) can achieve front-side emission, back-side emission, and integration with lenses through different electrode configurations and optical designs. These designs can be selected and optimized according to specific application requirements to improve the performance and ease of use of the laser. Whether used in optical communications, lidar, optical storage, 3D sensing, bio-imaging, or other fields, VCSELs have attracted widespread attention due to their unique structure and performance.

[0116] It should be noted that the solution of the present invention is also applicable to vertical cavity surface emitting lasers that do not include lenses. For example, in application scenarios with wavelengths such as 850nm for communication, lenses are generally not set when making VCSEL chips, but are made during the packaging process.

[0117] Another aspect of the present invention provides a vertical cavity surface emitting laser array, comprising a plurality of vertical cavity surface emitting lasers according to any embodiment of the present disclosure, wherein the vertical cavity surface emitting laser array is a 1D or 2D addressable laser array.

[0118] In some embodiments, a 1D addressable laser array refers to a laser array in which the VCSEL units can be independently controlled in a one-dimensional manner (e.g., from left to right). This array structure is suitable for application scenarios that require horizontal scanning or linear detection.

[0119] For example, in the lidar system of an autonomous vehicle, a 1D addressable VCSEL array can be used for horizontal scanning to detect obstacles in front of the vehicle. By controlling the lighting order and frequency of each VCSEL unit, fast and accurate horizontal scanning can be achieved to generate a three-dimensional point cloud map of the surrounding environment.

[0120] For example, in optical communication systems, 1D addressable VCSEL arrays can be used to build multi-channel optical fiber communication links. Each VCSEL unit can independently modulate and transmit data, thereby improving the data transmission capacity and flexibility of the system.

[0121] 2D addressable laser arrays allow each VCSEL unit to be independently controlled in two dimensions (i.e. horizontal and vertical directions). This array structure has higher flexibility and control accuracy, and is suitable for application scenarios that require complex scanning patterns or high-resolution detection.

[0122] For example, in consumer electronics products such as smartphones and tablets, 2D addressable VCSEL arrays are widely used in 3D imaging and facial recognition systems. By controlling the lighting order and intensity of each VCSEL unit in the array, an accurate 3D point cloud map can be generated to achieve high-precision face recognition, gesture recognition and other functions.

[0123] For example, in the perception system of self-driving cars, 2D addressable VCSEL arrays can be used to build high-precision solid-state LiDARs, which can scan in two directions (such as horizontal and vertical directions) to more comprehensively perceive pedestrians, vehicles, and other obstacles in the surrounding environment.

[0124] The size of the VCSEL array can be customized according to specific application requirements. For example, the VCSEL array size can reach 2440x2430μm, which is suitable for applications requiring high power output.

[0125] The emission wavelength and power of the VCSEL array are also customized according to application requirements. For example, the VCSEL array center wavelength has two options: 905nm and 940nm, and the output power can reach 35W.

[0126] For example, the vertical cavity surface emitting laser of the embodiment of the present disclosure can be used for high-speed data transmission, and the wavelength can be 850nm, 880nm, 910nm, 940nm, 980nm, or other wavelengths, and can be a single-hole chip or array, single-junction or multi-junction VCSEL. Among them, the four wavelengths of 850nm, 880nm, 910nm, and 940nm are the wavelengths of the light source equipped with multi-mode optical fiber specified by the industry. In addition, it can also be used in the field of sensing, and the wavelength can be 850nm, 905nm, 940nm, or other wavelengths, and can be a single chip, multiple chips or various array chips, single-junction or multi-junction VCSEL.

[0127] It is understandable that in addition to 1D and 2D addressing modes, there are more complex addressing modes such as interleaved interleaved luminescence, and a suitable addressing mode can be selected according to the specific application scenario. The vertical cavity surface emitting laser array can be a surface array in which the vertical cavity surface emitting lasers are regularly distributed or randomly distributed.

[0128] 1D and 2D addressable laser arrays provide more flexibility and possibilities for the application of vertical cavity surface emitting lasers, making VCSEL technology widely used in lidar, 3D imaging, communication and telecommunications and other fields.

[0129] Figure 6 The flowchart of the method for manufacturing a vertical cavity surface emitting laser according to an embodiment of the present invention is schematically shown.

[0130] Another aspect of the present invention provides a method for preparing a vertical cavity surface emitting laser, such as Figure 6 As shown, for example, operations S610 to S640 are included.

[0131] In operation S610, an N-type Bragg reflection layer, an active region, and a preset number of AlGaAs layers are sequentially grown on a substrate under a second temperature condition.

[0132] In operation S620, the temperature is lowered to a first temperature, and a current confinement layer is grown on a preset number of AlGaAs layers, wherein the first temperature ranges from 200°C to 430°C.

[0133] In operation S630 , the current confinement layer is annealed, and doping is performed on a local region of the annealed current confinement layer to form a current injection region.

[0134] In operation S640 , the temperature is raised to a second temperature, and a P-type Bragg reflective layer is grown on the locally doped current confinement layer.

[0135] In some embodiments, for example, GaAs is first selected as the substrate material because GaAs has a similar lattice constant to the subsequently grown AlGaAs layer, which is beneficial for reducing dislocations and defects.

[0136] Then, under the second temperature condition (e.g., 500°C-750°C, the specific temperature depends on the equipment and process requirements), an N-type Bragg reflector (N-DBR) is grown on the GaAs substrate in sequence. The Bragg reflector is formed by alternating the growth of multiple layers of materials with different refractive indices to achieve high reflectivity.

[0137] The active region and a preset number of AlGaAs layers are regrown.

[0138] In the design of the active region, performance parameters such as material gain and wavelength need to be considered. For example, the active region uses the InGaAs / GaAsP material system because InGaAs is in a compressive strain state and GaAsP can provide strain compensation, thereby providing higher gain.

[0139] A preset number of AlGaAs layers are grown on the active region, which will be used to isolate the current confinement layer grown subsequently.

[0140] Then, the growth temperature is lowered to a first temperature range (200°C~430°C), which is to ensure that the subsequent current limiting layer can grow uniformly and densely.

[0141] It should be noted that different deposition processes have different corresponding temperature ranges. For example, when the current limiting layer is grown using the MBE (Molecular Beam Epitaxy) process, the current limiting layer can be grown between 200°C and 300°C. When the current limiting layer is grown using the MOCVD (Metal-Organic Chemical Vapor Deposition) process, the current limiting layer can be grown between 300°C and 430°C.

[0142] A current limiting layer is grown on a preset number of AlGaAs layers. The function of the current limiting layer is to limit the light emitting area of ​​the laser by controlling the flow area of ​​the current, thereby achieving more efficient energy concentration.

[0143] The current limiting layer is then annealed to obtain a semi-insulating GaAs or AlGaAs thin film material, while improving its quality and stability. By reducing the growth temperature to below 430°C, such as 200°C, and annealing, a non-conductive semi-insulating GaAs thin film material can be formed, and its electrical properties have undergone fundamental changes. This is because the chemical ratio of the material has changed, and the GaAs film has become arsenic-rich, and the arsenic-rich degree can reach more than 1%. After annealing, these excess As form arsenic precipitates in the lattice, which is the reason why the material changes from conductive to semi-insulating. In addition, this thin film material grown under low temperature conditions has the advantages of high mobility, short carrier recombination lifetime, and stable performance, and has important application value in the fields of microelectronics and optoelectronics. In particular, the thin layer material grown under such low temperature conditions can reduce or eliminate the back gate effect of the transistor. Similar results are also achieved for low-temperature grown AlGaAs materials.

[0144] Then, doping is performed in a local area of ​​the annealed current limiting layer to form a current injection region, which will serve as an electrode contact point of the laser for injecting current.

[0145] Finally, the temperature is raised to the second temperature to ensure that the P-type Bragg reflector (P-DBR) can grow at an appropriate temperature. The growth of the P-type Bragg reflector is completed on the locally doped current limiting layer. The P-DBR and N-DBR together constitute the resonant cavity of the laser, which determines the laser's lasing wavelength and performance.

[0146] It should be noted that after the growth of the current limiting layer is completed at the first growth temperature, the sample generally needs to be taken out of the growth chamber for some process treatment, such as doping treatment to form a current injection area, and then the sample is reloaded into the growth chamber to complete the P-type Bragg growth at the second growth temperature.

[0147] The above preparation method describes in detail the production process of vertical cavity surface emitting laser, including key steps such as growing N-type Bragg reflection layer, active area, AlGaAs layer, current limiting layer and P-type Bragg reflection layer in sequence starting from GaAs substrate. By precisely controlling these steps, high-performance vertical cavity surface emitting lasers can be prepared to meet various application requirements. Using AlGaAs or GaAs semi-insulating thin layers grown at low temperature by MBE or MOCVD as the current limiting layer of AlGaAs / GaAs VCSEL avoids a series of reliability problems caused by the mismatch stress introduced by Al2O3 and AlGaAs / GaAs usually formed by the oxidation limiting process.

[0148] It is understandable that, in addition to the above steps, the preparation of a vertical cavity surface emitting laser may also include related steps such as P electrode preparation, substrate thinning, N electrode preparation, annealing, electroplating, testing and chip cutting.

[0149] The details not included in the method embodiment section are similar to those in the device embodiment section. Please refer to the device embodiment section and will not be repeated here.

[0150] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present invention. The attached method embodiment provides the elements of various steps in an exemplary order and is not intended to be limited to a specific order or hierarchy.

[0151] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present invention. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted when they may cause confusion in the understanding of the present invention. In addition, the shapes, sizes, and positional relationships of the components in the drawings do not reflect the actual sizes, proportions, and actual positional relationships.

[0152] In the foregoing detailed description, various features are grouped together in a single embodiment to simplify the invention. This disclosure method should not be interpreted as reflecting such an intention.

[0153] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. With respect to the term "comprising" used in the specification, the word is covered in a manner similar to the term "including". Any term "or" used in the specification is intended to mean "non-exclusive or".

[0154] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A vertical cavity surface emitting laser, characterized in that: include: A substrate, an N-type Bragg reflection layer, an active region and a P-type Bragg reflection layer stacked in sequence; Wherein, a current limiting layer grown under a first temperature condition is arranged on a side of the P-type Bragg reflection layer close to the active region or in a P-type region of the active region; and / or A current limiting layer grown under the first temperature condition is provided on a side of the N-type Bragg reflection layer close to the active region or in an N-type region of the active region; The first temperature is lower than a second temperature for growing the P-type Bragg reflection layer or the N-type Bragg reflection layer, the current limiting layer is a non-oxidized semi-insulating material, and a local area of ​​the current limiting layer is provided with a current injection area; Wherein, the material of the current limiting layer is Al x Ga 1-x As, 0≤x≤1.

2. The vertical cavity surface emitting laser according to claim 1, characterized in that: The thickness of the current confinement layer is less than or equal to one quarter of the optical wavelength.

3. The vertical cavity surface emitting laser according to claim 2, characterized in that: The current limiting layer is a single layer or multiple adjacent layers arranged in pairs; Wherein, in the case that the current confinement layer is multi-layered, the aluminum components of adjacent current confinement layers are different, and the thickness of each layer of the current confinement layer is equal to one quarter of the optical wavelength.

4. The vertical cavity surface emitting laser according to claim 1, characterized in that: The current injection region is doped with magnesium or zinc ions, and the diameter of the current injection region is 1 μm to 50 μm.

5. The vertical cavity surface emitting laser according to claim 1, characterized in that: One or more oxide layers are arranged on a side of the current limiting layer away from the active area; Wherein, an oxidation hole is provided in the region of the oxide layer corresponding to the current injection region, and the size of the oxidation hole is larger than the size of the current injection region; and In the case where multiple oxide layers are provided, the size of each oxide hole remains unchanged or increases as the distance from the current confinement layer increases.

6. The vertical cavity surface emitting laser according to claim 1, characterized in that: An ion implantation region is provided on a side of the current limiting layer away from the active region; Wherein, the implanted ions in the ion implantation area include: H + , O + 、N + and F + .

7. The vertical cavity surface emitting laser according to claim 1, characterized in that: The active area is one or more; Wherein, when there are a plurality of active regions, tunnel junctions are arranged between adjacent active regions.

8. The vertical cavity surface emitting laser according to claim 1, characterized in that: Also includes at least one of the following: P electrode and N electrode; lens; The P electrode and the N electrode are arranged on the same side or different sides of the active area, and the P electrode is provided with a light-transmitting area for emitting laser light; The lens is arranged in the light-transmitting area.

9. A vertical cavity surface emitting laser array, characterized in that: It comprises a plurality of vertical cavity surface emitting lasers as described in any one of claims 1 to 8, wherein the vertical cavity surface emitting laser array is a 1D or 2D addressable laser array.

10. A method for preparing a vertical cavity surface emitting laser, characterized in that: include: Under the second temperature condition, an N-type Bragg reflection layer, an active region and a preset number of AlGaAs layers are sequentially grown on the substrate; Cooling to a first temperature and growing a current limiting layer on the preset number of AlGaAs layers, wherein the first temperature ranges from 200° C. to 430° C.; Annealing the current limiting layer, and doping a local area of ​​the annealed current limiting layer to form a current injection area; as well as The temperature is raised to the second temperature, and a P-type Bragg reflection layer is grown on the locally doped current limiting layer.

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