Vertical cavity light emitting device and light output array for short distance high speed optical communication

Abstract

The application discloses a vertical resonant cavity light-emitting device and an optical output array for short-distance high-speed optical communication, which comprises, from bottom to top, a first electrode, a substrate, a reflecting layer, an epitaxial structure, a grid electrode and a microlens, wherein the reflecting layer is formed on the substrate; the epitaxial structure comprises a first semiconductor layer, an active light-emitting layer and a second semiconductor layer; the grid electrode covers the epitaxial structure and is electrically connected with the second semiconductor layer; the grid electrode is opposite to the reflecting layer at a certain interval, and the reflecting layer and the grid electrode form a vertical optical resonant cavity. The grid electrode is used as the upper reflecting interface of the resonant cavity and cooperates with the reflecting layer to form the vertical resonant cavity, so that the directivity, spectral stability and array consistency are improved, and the high light transmittance and current expansion are considered.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, specifically to a vertical resonant cavity light-emitting device and an optical output array for short-distance high-speed optical communication. Background Technology

[0002] Artificial Intelligence (AI) is a branch of computer science that aims to study and develop theories, methods, technologies, and application systems for simulating, extending, and expanding human intelligence. Currently, we are experiencing a boom in AI. AI, especially large-scale models and generative AI, places extremely high demands on computing power and data transmission speed, requiring the processing of massive amounts of data, such as large models with trillions of parameters, and complex matrix operations. This typically necessitates the use of GPU clusters (such as NVIDIA H100 / H200) or TPUs (Tensor Processing Units) for large-scale parallel computing.

[0003] Currently, on-board data transmission in GPU clusters still relies on copper wire transmission technology. However, copper wire transmission is limited by the limited space on the board and heat dissipation efficiency, making it difficult for data transmission capacity to increase exponentially. In the long run, it can no longer meet the needs of artificial intelligence for large-scale and efficient data processing.

[0004] Optical communication technology is a communication method that uses light waves as the information carrier. It transmits optical signals through optical fibers, enabling high-speed, high-capacity, and long-distance information transmission. Currently, optical communication technology is mainly used in two major fields: information transmission and sensing and detection. Information transmission is the absolute core, supporting the digital operation of modern society. In the AI ​​era, optical communication is key to solving the "computing power transmission bottleneck." AI training requires the high-speed transmission of massive amounts of data from storage to computing (GPUs), and optical communication provides a high-speed channel far exceeding that of traditional electrical signals, serving as the underlying technology supporting computing power networks.

[0005] Optical communication technology light sources are mainly divided into two categories: lasers and light-emitting diodes (LEDs). Lasers have the characteristics of good directionality, good monochromaticity, and high brightness, making them the absolute mainstream in high-speed, long-distance transmission. However, in short-distance transmission, lasers have problems such as high cost, high power consumption, and high heat dissipation requirements compared to LEDs. From a technical and market perspective, micro LEDs are more suitable for short-distance (within 1 meter) high-speed optical communication applications.

[0006] Optical communication technology places high demands on the luminous efficiency, directivity, spectral stability, and array uniformity of miniature light-emitting diodes (LEDs). Current miniature LEDs still suffer from the following problems: (1) Bottom emitted light loss: The micro light-emitting diode emits light in a divergent manner. Some of the downward emitted light is absorbed or scattered after entering the substrate, which limits the external quantum efficiency. (2) Conflict between current spread and light shielding: ITO and other transparent conductive layers have high resistance, and current congestion and heat generation increase in micro-sized structures. Traditional metal electrodes have low resistance but significant light shielding. Therefore, there is an urgent need for a light-emitting device, light output array, and optical interconnect system suitable for short-distance high-speed optical communication that can solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to provide a vertical resonant cavity light-emitting device and light output array suitable for short-distance high-speed optical communication. The device uses grid electrodes as the upper reflection interface of the optical resonant cavity and cooperates with the reflective layer to form a vertical resonant cavity, thereby improving the directionality, spectral stability and array consistency, while taking into account both high light transmittance and current spread.

[0008] To achieve the above objectives, the present invention provides a vertical resonant cavity light-emitting device for short-range high-speed optical communication, comprising a substrate, a reflective layer, an epitaxial structure, a grid electrode, a microlens, and a first electrode. The reflective layer is formed on the substrate. The epitaxial structure includes a first semiconductor layer, an active light-emitting layer, and a second semiconductor layer sequentially formed on the reflective layer. The grid electrode covers the epitaxial structure and is electrically connected to the second semiconductor layer. The grid electrode and the reflective layer are positioned opposite each other at a certain distance, and the reflective layer and the grid electrode constitute a vertical optical resonant cavity. The microlens covers all or part of the grid electrode. The first electrode is formed on the back side of the substrate.

[0009] Preferably, the epitaxial structure forms a stepped structure on the side away from the substrate, and a transparent dielectric planarization layer covering the epitaxial structure is formed on the stepped structure. The transparent dielectric planarization layer fills the stepped structure so that the side away from the substrate is a flat surface. The network electrode covers the flat surface of the transparent dielectric planarization layer and is electrically connected to the second semiconductor layer through an electrode layer penetrating the transparent dielectric planarization layer.

[0010] Specifically, a limiting step or limiting groove is formed around the periphery of the transparent dielectric planarization layer. The center of the limiting step or limiting groove overlaps with the light-emitting center of the vertical resonant cavity light-emitting device. The microlens covers the grid electrode with the limiting step or the limiting groove as its boundary, so that the center of the microlens is aligned with the light-emitting center. The grid electrode fully covers the limiting step or the limiting groove, or extends beyond the limiting step or the limiting groove. In the prior art, microlens alignment errors can lead to inconsistent brightness / coupling efficiency, and encapsulation stress can easily cause cracks, delamination, and long-term drift. In contrast, when forming the microlens in this invention, the microlens can be automatically limited within the limiting step or the limiting groove and automatically overlap with the light-emitting center, effectively improving the self-alignment degree of the microlens and the light-emitting center, and improving the light emission consistency, collimation, and coupling efficiency of the Bulk GaN vertical resonant cavity light-emitting device.

[0011] Preferably, the microlens covers the grid electrode with the outer edge of the grid electrode as the boundary. The grid structure of the grid electrode not only increases the bonding force between the microlens and the grid electrode, but also helps to accurately position the microlens.

[0012] Preferably, the substrate is a gallium nitride substrate, and both the reflective layer and the epitaxial structure are nitride epitaxial layers. This invention grows a nitride reflective layer and an epitaxial structure on a gallium nitride substrate, exhibiting extremely low dislocation density and extremely high crystal quality. This results in a significant improvement in internal quantum efficiency (IQE) and a substantial extension of device lifetime.

[0013] Specifically, the gallium nitride substrate is nonpolar or semipolar, which can eliminate or significantly weaken the polarization electric field, making the overlap of electron and hole wave functions higher, thereby significantly shortening the carrier lifetime and improving the modulation bandwidth of the device.

[0014] Specifically, the reflective layer is a porous DBR reflective layer and includes alternately stacked dense layers and porous layers, wherein the dense layer is a dense gallium nitride layer and the porous layer is a porous gallium nitride layer.

[0015] Specifically, the thickness of the single-layer dense gallium nitride layer is 30~300nm, the thickness of the single-layer porous gallium nitride layer is 30~300nm, the number of alternation periods of the porous DBR reflective layer is 6~40, and the porosity of the porous gallium nitride layer is 20–80%.

[0016] Specifically, the dense gallium nitride layer is a lightly doped gallium nitride layer, and the porous gallium nitride layer is obtained by electrochemical treatment of a heavily doped gallium nitride layer; the doping concentration of the heavily doped gallium nitride layer is at least one order of magnitude higher than that of the lightly doped gallium nitride layer.

[0017] Preferably, the dense gallium nitride layer is a lightly doped gallium nitride layer, and the porous gallium nitride layer is obtained by electrochemical treatment of a heavily doped gallium nitride layer; the doping concentration of the heavily doped gallium nitride layer is at least one order of magnitude higher than that of the lightly doped gallium nitride layer.

[0018] In this invention, the porous DBR reflective layer, the first semiconductor layer, the active light-emitting layer, and the second semiconductor layer are all group III nitride epitaxial layers. In the epitaxial structure of this invention, the gallium nitride substrate, the porous DBR reflective layer, the first semiconductor layer, the active light-emitting layer, and the second semiconductor layer all employ a group III nitride material system, particularly gallium nitride. The lattice constants and coefficients of thermal expansion of each structural layer in the epitaxial structure are very close, effectively reducing lattice mismatch and thermal stress at the interfaces, thereby reducing defect density and improving device performance and reliability.

[0019] Preferably, the active light-emitting layer is a single quantum well or a double quantum well. The light emission of a micro LED originates from the recombination of electrons in the conduction band and holes in the valence band. Since the energy band itself has a certain width (energy range), the energy difference (i.e., photon energy) during electron-hole recombination is not a fixed value but fluctuates within a range. This leads to natural spectral broadening and low light purity. In contrast, the active light-emitting layer of this invention, being a single quantum well or a double quantum well, can reduce carrier transport time, improve response speed, reduce spectral broadening, improve light purity, and reduce signal distortion during transmission.

[0020] Preferably, the thickness of the grid electrode is 50-1500 nm, the grid linewidth of the grid electrode is 0.3-5 µm, the spacing between adjacent parallel grid lines of the grid electrode is 3-30 µm, the aperture ratio of the grid electrode is 70-95%, the first metal layer is a nickel layer, and the second metal layer is a gold layer, so that the equivalent reflectivity is 10-60%, and the divergence angle of the light output by the vertical resonant cavity light-emitting device along the vertical direction is less than or equal to 30°.

[0021] Preferably, the modulation frequency of the vertical resonant cavity light-emitting device is 1–100 GHz and the full width at half maximum (FWHM) of the spectrum is <10 nm.

[0022] The present invention also provides an optical output array, including a plurality of vertical resonant cavity light-emitting devices as described above, wherein the plurality of vertical resonant cavity light-emitting devices are arranged in a matrix on a carrier plate, and all the vertical resonant cavity light-emitting devices have the same light emission direction.

[0023] Specifically, the multiple vertical resonant cavity light-emitting devices on the light output array are arranged in a rectangular, circular, or hexagonal array.

[0024] Specifically, the spacing between any two closest vertical resonant cavity light-emitting devices on the light output array is equal, with a spacing of 10~80 µm.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: On the one hand, the vertical resonant cavity light-emitting device of this patent adopts an optical resonant cavity composed of a reflective layer and a grid electrode. In particular, the grid electrode is used as the top reflective interface. The hole structure on it can not only improve the directionality, spectral stability and array consistency, but also further improve the directionality (collimation) and coupling tolerance by combining with microlenses, and reduce the alignment cost. On the other hand, the grid electrode has both low resistance current expansion and high light transmittance, which alleviates the contradiction between current congestion and light blocking in the vertical resonant cavity light-emitting device. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the extensional structure of the present invention.

[0027] Figure 2 This is a cross-sectional schematic diagram of the porous DBR reflective layer in the epitaxial structure of the present invention.

[0028] Figure 3 This is a schematic diagram of the structure of a vertical resonant cavity light-emitting device in one embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram of the structure of a vertical resonant cavity light-emitting device in another embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of the optical output array in this invention.

[0031] Figure 6 This is a structural diagram of the grid electrode in another embodiment of the present invention. Detailed Implementation

[0034] To illustrate the technical content, structural features, objectives, and effects of the present invention in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0035] refer to Figure 1This invention discloses a vertical resonant cavity light-emitting device 100 for short-range high-speed optical communication, comprising a substrate 1, a reflective layer, an epitaxial structure, a grid electrode 7, a microlens 9, and a first electrode 8. The reflective layer is formed on the substrate 1. The epitaxial structure includes a first semiconductor layer 4, an active light-emitting layer 5, and a second semiconductor layer 6 sequentially formed on the reflective layer. The grid electrode 7 covers the epitaxial structure and is connected to the second semiconductor layer 6. The grid electrode 7 includes a first metal layer and a second metal layer sequentially deposited. The reflective layer and the grid electrode 7 are opposite each other at a certain distance and constitute a vertical optical resonant cavity. The microlens 9 covers all or part of the grid electrode 7. The first electrode 8 is formed on the back side of the substrate 1.

[0036] In this embodiment, the reflective layer is a porous DBR reflective layer 2. Of course, in another embodiment, the porous DBR reflective layer 2 can be replaced by other types of reflective layers, with a DBR reflective layer being preferred.

[0037] The first semiconductor layer 4 is an n-type epitaxial layer, specifically an n-type gallium nitride layer or an n-type AlGaN layer. The second semiconductor layer 6 is a p-type epitaxial layer, specifically a p-type gallium nitride layer or a p-type AlGaN layer.

[0038] In this design, a porous DBR reflective layer 2 is grown on substrate 1, and a buffer layer 3 is grown on the porous DBR reflective layer 2. A first semiconductor layer 4, an active light-emitting layer 5, and a second semiconductor layer 6 are sequentially grown on the buffer layer 3. The buffer layer 3 can be an AlN layer or a GaN layer.

[0039] The microlens 9 covers the grid electrode 7 with the outer edge of the grid electrode 7 as the boundary. The grid structure of the grid electrode 7 not only increases the bonding force between the microlens 9 and the grid electrode 7, but also helps to accurately position the microlens 9.

[0040] The substrate 1 is a gallium nitride (GaN) substrate, enabling the vertical-cavity light-emitting device (VCSEL) to be a Bulk GaN VCSEL. Growing a porous DBR reflective layer 2 of gallium nitride and an epitaxial structure of nitride on the GaN substrate results in extremely low dislocation density and extremely high crystal quality, leading to a significant improvement in internal quantum efficiency (IQE) and a substantial extension of device lifetime. Specifically, the GaN substrate 1 is nonpolar or semipolar, which can eliminate or significantly weaken the polarization electric field, resulting in a higher overlap between electron and hole wave functions, thereby significantly shortening carrier lifetime and increasing the modulation bandwidth of the device.

[0041] refer to Figure 2The reflective layer is a porous DBR reflective layer 2 comprising alternating stacked dense and porous layers. The dense layer is a dense gallium nitride layer 2a, and the porous layer is a porous gallium nitride layer 2b. This invention grows a porous DBR reflective layer 2 of gallium nitride material on a gallium nitride substrate, exhibiting extremely low dislocation density and extremely high crystal quality. This results in a significant improvement in internal quantum efficiency (IQE) and a substantial extension of device lifetime.

[0042] The thickness of the single-layer dense gallium nitride layer 2a is 30~300nm, the thickness of the single-layer porous gallium nitride layer 2b is 30~300nm, the number of alternating periods of the porous DBR reflective layer 2 is 6~40, and the porosity of the porous gallium nitride layer 2b is 20–80%.

[0043] In this embodiment, the dense gallium nitride layer 2a is a lightly doped gallium nitride layer, and the porous gallium nitride layer 2b is obtained by electrochemical treatment of a heavily doped gallium nitride layer; the doping concentration of the heavily doped gallium nitride layer is at least one order of magnitude higher than that of the lightly doped gallium nitride layer. Specifically, the doping concentration of the lightly doped gallium nitride layer is 1×10^17–5×10^18 cm^2. - ³; The doping concentration of the heavily doped gallium nitride layer before electrochemical treatment is 1×10^19–5×10^20 cm⁻¹ - ³.

[0044] In this invention, the porous DBR reflective layer 2 is formed by alternating epitaxial growth of lightly doped gallium nitride layers and heavily doped gallium nitride layers, and then obtained by electrochemical treatment.

[0045] Specifically, lightly doped gallium nitride (GaN) layers and heavily doped GaN layers are first stacked alternately on a gallium nitride substrate 1. During electrochemical treatment of the heavily doped GaN layer, the dopant elements are preferentially displaced to form pores. Therefore, the lightly doped GaN layer serves as a dense GaN layer 2a, and the heavily doped GaN layer, after electrochemical treatment, serves as a porous GaN layer 2b. In this embodiment, both the lightly and heavily doped GaN layers generally use Si as the dopant element, with a Si doping concentration of 1×10^17–5×10^18 cm⁻¹ in the lightly doped GaN layer. - ³, the Si heavy doping concentration in the heavily doped gallium nitride layer is 1×10^19–5×10^20 cm⁻¹ - ³. The thickness of the single-layer dense gallium nitride layer 2a or the porous gallium nitride layer 2b is 30–300 nm, with an alternation period of 6–40. The optical thickness (physical thickness × refractive index) of each lightly doped gallium nitride layer and heavily doped gallium nitride layer is typically designed to be one-quarter of the target wavelength. When light is reflected at the interface, the optical path difference is exactly an integer multiple of half the wavelength, resulting in mutual reinforcement of reflected light.

[0046] The active light-emitting layer 5 is a single quantum well or a double quantum well. In this invention, the active light-emitting layer 5 includes N pairs of quantum wells, where N≤2, and preferably a single quantum well (SQW) or a double quantum well (DQW). Multiple quantum well structures can lead to uneven carrier distribution between different wells, causing band fluctuations and spectral broadening. Using a single quantum well (SQW) or a very small number of quantum wells can reduce carrier transport time, improve response speed, reduce spectral broadening, improve light purity, and reduce signal distortion during transmission.

[0047] To further explain, a single quantum well (SQW) consists of a first GaN barrier layer, an InGaN well layer, and a second GaN barrier layer formed sequentially; a double quantum well (DQW) consists of a first GaN barrier layer, a first InGaN well layer, a second GaN barrier layer, a second InGaN well layer, and a third GaN barrier layer formed sequentially.

[0048] In this invention, the porous DBR reflective layer 2, the first semiconductor layer 4, the active light-emitting layer 5, and the second semiconductor layer 6 are all group III nitride epitaxial layers, particularly gallium nitride epitaxial layers. In the epitaxial structure of this invention, the gallium nitride substrate 1, the porous DBR reflective layer 2, the first semiconductor layer 4, the active light-emitting layer 5, and the second semiconductor layer 6 all employ a group III nitride material system, especially gallium nitride. The lattice constants and coefficients of thermal expansion of each structural layer in the epitaxial structure are very close, effectively reducing lattice mismatch and thermal stress at the interface, thereby reducing defect density and improving device performance and reliability.

[0049] The holes in the grid electrode 7 can be square. (Reference) Figure 6 The holes in the grid electrode 7 can also be rhomboid, hexagonal, pentagonal, octagonal, etc. The thickness of the grid electrode 7 is 50–1500 nm, the grid linewidth is 0.3–5 µm, the spacing between adjacent parallel grid lines is 3–30 µm, and the porosity is 70–95%. The first metal layer is nickel (Ni), and the second metal layer is gold (Au). This results in an equivalent reflectivity of 10–60%. The grid electrode 7 can adjust the light emission angle, reduce the light emission range, and improve the directionality of the light. The grid electrode 7 of this invention is formed by a lift-off process or an electroplating process.

[0050] Preferably, the vertical resonant cavity light-emitting device 100 of this patent can control the divergence angle of the output light to less than or equal to 30°, and the modulation frequency of the vertical resonant cavity light-emitting device 100 is 1–100 GHz and the full width at half maximum (FWHM) of the spectrum is <10 nm.

[0051] refer to Figure 3The epitaxial structure forms a stepped structure on the side away from the substrate 1. A transparent dielectric planarization layer 12 covering the epitaxial structure is formed on the stepped structure. The transparent dielectric planarization layer 12 fills the stepped structure so that the side away from the substrate 1 is a flat surface. The network electrode 7 covers the flat surface of the transparent dielectric planarization layer 12 and is electrically connected to the second semiconductor layer 6 through an electrode layer 13 penetrating the transparent dielectric planarization layer 12.

[0052] In this design, a passivation layer 11 is covered on the second epitaxial layer 6, and a transparent dielectric planarization layer 12 is formed on the passivation layer 11. The electrode layer 13 passes through the passivation layer 11 and the transparent dielectric planarization layer 12 and is electrically connected to the second epitaxial layer 6. A grid electrode 7 is electrically connected to the electrode layer 13, and a pad electrode 14 is electrically connected to both the grid electrode 7 and the electrode layer 13. The pad electrode 14 can be directly electrically connected to the grid electrode 7, and then electrically connected to the electrode layer 13 through the grid electrode 7. Alternatively, both the pad electrode 14 and the grid electrode 7 can be electrically connected to the electrode layer 13 through a metal interconnect structure. The electrode layer 13 is the ohmic contact portion of a p-type electrode.

[0053] refer to Figure 4 The transparent dielectric planarization layer 12 has a limiting step or limiting groove 91 formed around its periphery. The center of the limiting step or limiting groove 91 overlaps with the light-emitting center of the vertical resonant cavity light-emitting device 100. The microlens 9 covers the grid electrode 7 with the limiting step or limiting groove 91 as its boundary. The grid electrode 7 is fully covered within the limiting step or the limiting groove 91, or extends outside the limiting step or the limiting groove 91. In the prior art, alignment errors of the microlens 9 can lead to inconsistent brightness / coupling efficiency, and encapsulation stress can easily cause cracks, delamination, and long-term drift. In contrast, when the microlens 9 is formed in this invention, it can be automatically limited within the limiting step or limiting groove, and the center of the microlens 9 automatically overlaps with the light-emitting center, effectively improving the self-alignment degree of the microlens 9 and the light-emitting center, and improving the light emission consistency, collimation, and coupling efficiency of the vertical resonant cavity light-emitting device.

[0054] In this embodiment, the microlens 9 achieves self-alignment through limiting steps or limiting slots provided on the grid electrode 7 / transparent dielectric planarization layer 12. Silicone colloid is applied to the surface of the grid electrode 7 via a dispensing process, and the shape of the silicone (i.e., the microlens 9) is adjusted using a thermal reflow process. The surface tension of the silicone droplets drives their automatic contraction, forming a stable spherical or parabolic surface with the smallest surface area and lowest energy, and automatically positioning itself within the limiting steps or limiting slots 91. The center of the limiting steps or limiting slots 91 is designed to coincide with the light-emitting center of the vertical resonant cavity light-emitting device. Therefore, after thermal reflow, the center of the microlens 9, automatically positioned within the limiting steps or limiting slots, is self-aligned with the light-emitting center, improving the light emission consistency, collimation, and coupling efficiency of the vertical resonant cavity light-emitting device. Of course, the microlens 9 can also be made of ZnO or SU-8 material, formed by photolithography or by photolithography followed by the formation of the microlens 9.

[0055] In this embodiment, the microlens 9 is made of silicone, with a diameter / width of 8-70μm, a height of 5-80μm, a radius of curvature of 20-250μm, and a self-alignment deviation of ≤±3μm.

[0056] refer to Figure 5 The present invention also discloses a light output array, comprising a plurality of the aforementioned vertical cavity light-emitting devices 100, which are arranged in a matrix at a certain spacing on a carrier plate 200. The matrix shape can be rectangular, honeycomb (regular hexagon / octagonal), or circular. The spacing between adjacent vertical cavity light-emitting devices 100 is 10-80 μm. In one specific embodiment, the number of vertical cavity light-emitting devices on a single light output array is set to 2-1000.

[0057] In Example 1, a vertical resonant cavity light-emitting device (VRF) emitting blue light in the 460–470 nm wavelength band using GaN material was fabricated. Specific parameters included: linewidth of the grid electrode 7 of 0.5–2.5 µm; spacing between adjacent parallel grid lines of the grid electrode 7 of 3–12 µm; porosity of 85–95%; and thickness of 100–600 nm. The thickness of the monolayer dense gallium nitride layer 2a was 30–300 nm, the thickness of the monolayer porous gallium nitride layer 2b was 30–300 nm, the alternation period number of the porous DBR reflective layer 2 was 10–28, and the porosity of the porous gallium nitride layer 2b was 40–75%. Both the lightly doped and heavily doped gallium nitride layers generally used Si doping elements, with a light Si doping concentration of 1 × 10^17–5 × 10^18 cm⁻¹. - ³, Si heavy doping concentration is 1×10^19–5×10^20 cm⁻¹ -³. The spacing between adjacent vertical resonant cavity light-emitting devices is 10-40 μm. The microlens 9 is made of silicone, with a diameter / width of 8-30 μm, a height of 10-50 μm, and a radius of curvature of 20-100 μm. When the spacing between adjacent vertical resonant cavity light-emitting devices is ≤20 μm, the self-alignment deviation is ≤±1 μm.

[0058] In Example 2, a vertical resonant cavity light-emitting device (VRF) emitting green light in the 535–540 nm wavelength band using GaN material was fabricated. Specific parameters included: a grid electrode linewidth of 0.5–4 µm; a spacing between adjacent parallel grid lines of the grid electrode 7 of 5–25 µm; an aperture ratio of 75–93%; and a thickness of 100–1000 nm. The thickness of the monolayer dense gallium nitride layer 2a was 30–300 nm, the thickness of the monolayer porous gallium nitride layer 2b was 30–300 nm, the alternation period number of the porous DBR reflective layer 2 was 12–35, and the porosity of the porous gallium nitride layer 2b was 30–70%. Both the lightly doped and heavily doped gallium nitride layers generally used Si doping elements, with a light Si doping concentration of 1 × 10^17–5 × 10^18 cm⁻¹. - ³, Si heavy doping concentration is 1×10^19–5×10^20 cm⁻¹ - ³. The spacing between adjacent vertical resonant cavity light-emitting devices is 20-80 μm. The microlens 9 is made of silicone, with a diameter / width of 16-70 μm, a height of 10-70 μm, and a radius of curvature of 40-250 μm. When the spacing between adjacent vertical resonant cavity light-emitting devices is ≤30 μm, the self-alignment deviation is ≤±1 μm.

[0059] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the scope of the present invention are still within the scope of the present invention.

Claims

1. A vertical resonant cavity light-emitting device for short-range high-speed optical communication, characterized in that, include: Substrate; A reflective layer is formed on the substrate; The epitaxial structure includes a first semiconductor layer, an active light-emitting layer, and a second semiconductor layer sequentially formed on the reflective layer; A grid electrode is covered on the epitaxial structure and electrically connected to the second semiconductor layer, which is opposite to the reflective layer at a certain distance, and the reflective layer and the grid electrode form a vertical optical resonant cavity; Microlenses, which may cover all or part of the grid electrodes; The first electrode is formed on the back side of the substrate away from the reflective layer.

2. The vertical resonant cavity light-emitting device according to claim 1, characterized in that, The epitaxial structure forms a stepped structure on the side away from the substrate. A transparent dielectric planarization layer is formed on the stepped structure to cover the epitaxial structure. The transparent dielectric planarization layer fills the stepped structure so that the side away from the substrate is a flat surface. The network electrode covers the flat surface of the transparent dielectric planarization layer and is electrically connected to the second semiconductor layer through an electrode layer that penetrates the transparent dielectric planarization layer.

3. The vertical resonant cavity light-emitting device according to claim 2, characterized in that, The periphery of the transparent dielectric planarization layer forms a limiting step or a limiting groove, the center of the limiting step or the limiting groove overlaps with the light emission center of the vertical resonant cavity light emission device, the microlens covers the grid electrode with the limiting step or the limiting groove as the boundary, so that the center of the microlens is aligned with the light emission center; the grid electrode fully covers the limiting step or fully covers the limiting groove or extends beyond the limiting step or beyond the limiting groove.

4. The vertical resonant cavity light-emitting device according to claim 1, characterized in that, The microlens covers the grid electrode with the outer edge of the grid electrode as its boundary.

5. The vertical resonant cavity light-emitting device according to claim 1, characterized in that, The substrate is a gallium nitride substrate, and both the reflective layer and the epitaxial structure are nitride epitaxial layers.

6. The vertical resonant cavity light-emitting device according to claim 5, characterized in that, The gallium nitride substrate is nonpolar or semipolar.

7. The vertical resonant cavity light-emitting device according to claim 1, characterized in that, The reflective layer is a porous DBR reflective layer and includes alternately stacked dense layers and porous layers, wherein the dense layer is a dense gallium nitride layer and the porous layer is a porous gallium nitride layer.

8. The vertical resonant cavity light-emitting device according to claim 7, characterized in that, The thickness of the single-layer dense gallium nitride layer is 30~300nm, the thickness of the single-layer porous gallium nitride layer is 30~300nm, the number of alternation periods of the porous DBR reflective layer is 6~40, and the porosity of the porous gallium nitride layer is 20–80%.

9. The vertical resonant cavity light-emitting device according to claim 7, characterized in that, The dense gallium nitride layer is a lightly doped gallium nitride layer, and the porous gallium nitride layer is obtained by electrochemical treatment of a heavily doped gallium nitride layer; the doping concentration of the heavily doped gallium nitride layer is at least one order of magnitude higher than that of the lightly doped gallium nitride layer.

10. The vertical resonant cavity light-emitting device according to claim 1, characterized in that, The active light-emitting layer is a single quantum well or a double quantum well.

11. The vertical resonant cavity light-emitting device according to claim 1, characterized in that, The thickness of the grid electrode is 50–1500 nm, the grid linewidth of the grid electrode is 0.3–5 µm, the spacing between adjacent parallel grid lines of the grid electrode is 3–30 µm, the aperture ratio of the grid electrode is 70–95%, the equivalent reflectivity of the grid electrode is 10–60%, and the divergence angle of the light output by the vertical resonant cavity light-emitting device along the vertical direction is less than or equal to 30°.

12. The vertical resonant cavity light-emitting device according to claim 1, characterized in that, The modulation frequency of the vertical resonant cavity light-emitting device is 1–100 GHz, and the full width at half maximum (FWHM) of the spectrum is <10 nm.

13. An optical output array, characterized in that, It includes a plurality of vertical resonant cavity light-emitting devices as described in any one of claims 1-12 above, wherein the plurality of vertical resonant cavity light-emitting devices are arranged in a matrix on a carrier plate, and all the vertical resonant cavity light-emitting devices have the same light emission direction.

14. An optical output array according to claim 13, characterized in that, The multiple vertical resonant cavity light-emitting devices on the light output array are arranged in a rectangular, circular, or hexagonal array.

15. An optical output array according to claim 13, characterized in that, The spacing between any two closest vertical resonant cavity light-emitting devices on the optical output array is equal, ranging from 10 to 80 µm.

Images