Light emitting device, method of manufacturing the same, and optical communication apparatus

Abstract

The present disclosure provides a light emitting device, a preparation method thereof and an optical communication device, and belongs to the technical field of optoelectronic manufacturing. The light emitting device comprises a plurality of light emitting units, each of which comprises a first electrode, a second electrode and a semiconductor stack; the semiconductor stack comprises a first semiconductor layer, a superlattice layer, an active layer and a second semiconductor layer which are sequentially stacked; the first electrode is electrically connected to the first semiconductor layer, and the second electrode is electrically connected to the second semiconductor layer; the superlattice layer and the active layer each comprise alternately stacked quantum well layers and quantum barrier layers; the number of quantum well layers of the active layer is less than the number of quantum well layers of the superlattice layer, the number of quantum barrier layers of the active layer is less than the number of quantum barrier layers of the superlattice layer; the thickness of the quantum well layers of the active layer is less than the thickness of the quantum well layers of the superlattice layer, and / or the thickness of the quantum barrier layers of the active layer is less than the thickness of the quantum barrier layers of the superlattice layer. The present disclosure can improve the bandwidth and transmission rate of the light emitting device for optical communication.

Description

Technical Field

[0001] This disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a light-emitting device, its fabrication method, and an optical communication device. Background Technology

[0002] The explosive growth of AI computing clusters has highlighted the shortcomings of traditional short-range interconnect solutions such as copper cables, lasers, and silicon photonics: copper cables suffer from short transmission distances and severe crosstalk; lasers have high power consumption and a high risk of single-point failures; and silicon photonics relies on overseas external light sources, posing a risk of supply disruptions. The industry urgently needs new solutions that offer low power consumption, high reliability, and high bandwidth. Gallium nitride-based blue-green Micro LEDs, with their micron-scale size, high brightness, low power consumption, and fast response, are crossing over from displays to optical communications. Their multi-quantum-well materials can simultaneously emit light and detect, laying the foundation for optical interconnect technology.

[0003] In related technologies, Micro LED chips used for optical communication aim to increase transmission rates by improving the -3dB communication bandwidth. Their epitaxial active region employs multiple quantum wells (more than 8) and a wide well / barrier thickness structure to enhance carrier concentration and recombination efficiency, thereby achieving higher luminous efficiency.

[0004] However, epitaxial structures employing multiple quantum wells (more than 8) and wide well / barrier thickness have a long carrier recombination lifetime (the average time it takes for a carrier to recombine and emit light in the quantum well after injection), which cannot meet the requirements for rapid switching of high-frequency signals. This results in insufficient response speed, limiting the further improvement of the -3dB communication bandwidth, and consequently affecting the transmission rate of light-emitting devices in Micro LED optical communication. Summary of the Invention

[0005] This disclosure provides a light-emitting device, a method for fabricating the same, and an optical communication apparatus, which can improve the bandwidth and transmission rate of the light-emitting device in optical communication while reducing power consumption. The technical solution is as follows: This disclosure provides a light-emitting device comprising a plurality of light-emitting units, each light-emitting unit comprising a first electrode, a second electrode, and a semiconductor stack; the semiconductor stack comprises a first semiconductor layer, a superlattice layer, an active layer, and a second semiconductor layer stacked sequentially; the first electrode is electrically connected to the first semiconductor layer, and the second electrode is electrically connected to the second semiconductor layer; both the superlattice layer and the active layer comprise alternately stacked plurality of quantum well layers and plurality of quantum barrier layers; the number of quantum well layers in the active layer is less than the number of quantum well layers in the superlattice layer, and the number of quantum barrier layers in the active layer is less than the number of quantum barrier layers in the superlattice layer; the thickness of the quantum well layers in the active layer is less than the thickness of the quantum well layers in the superlattice layer, and / or the thickness of the quantum barrier layers in the active layer is less than the thickness of the quantum barrier layers in the superlattice layer.

[0006] In another implementation of the present disclosure, the thickness of the quantum well layer of the active layer is 0.8 nm to 1.5 nm, and the thickness of the quantum barrier layer of the active layer is 5 nm to 12 nm.

[0007] In another implementation of the present disclosure, the thickness of the quantum well layer of the superlattice layer is 3 nm to 6 nm, and the thickness of the quantum barrier layer of the superlattice layer is 20 nm to 30 nm.

[0008] In another implementation of the present disclosure, the number of periods of the active layer is 2 to 3, and the number of periods of the superlattice layer is 4 to 10.

[0009] In another implementation of the present disclosure, the active layer and the quantum well layer of the superlattice layer are both InGaN layers, and the quantum barrier layers of the active layer and the superlattice layer are both GaN layers; the In content of the quantum well layer of the active layer is greater than the In content of the quantum well layer of the superlattice layer.

[0010] In another implementation of the present disclosure, the In content of the quantum well layer of the active layer is 12% to 18%, and the In content of the quantum well layer of the superlattice layer is 5% to 10%.

[0011] In another implementation of this disclosure, the quantum barrier layer of the active layer is Si-doped, and the Si doping concentration is 1×10⁻⁶. 17 cm -3 Up to 1×10 18 cm -3 .

[0012] In another implementation of this disclosure, the quantum barrier layer furthest from the first semiconductor layer in the active layer is Mg-doped, and the Mg doping concentration is 1×10⁻⁶. 17 cm -3 Up to 1×10 18 cm -3 .

[0013] This disclosure provides an optical communication device, which includes an optical fiber and a light-emitting device as described above.

[0014] This disclosure provides a method for fabricating a light-emitting device, the method comprising: growing a first semiconductor layer on the surface of a substrate; growing a superlattice layer on the first semiconductor layer; growing an active layer on the superlattice layer, wherein both the superlattice layer and the active layer comprise alternating layers of multiple quantum well layers and multiple quantum barrier layers; wherein the number of quantum well layers in the active layer is less than the number of quantum well layers in the superlattice layer, the number of quantum barrier layers in the active layer is less than the number of quantum barrier layers in the superlattice layer, the thickness of the quantum well layers in the active layer is less than the thickness of the quantum well layers in the superlattice layer, and / or the thickness of the quantum well barriers in the active layer is less than the thickness of the quantum barrier layers in the superlattice layer; growing a second semiconductor layer on the active layer; forming a first electrode and a second electrode, wherein the first electrode is electrically connected to the first semiconductor layer, and the second electrode is electrically connected to the second semiconductor layer.

[0015] The beneficial effects of the technical solutions provided in this disclosure include at least the following: The light-emitting device provided in this disclosure divides the active region of the semiconductor stack into a superlattice layer and an active layer grown sequentially, both of which contain alternating quantum well layers and quantum barrier layers. The superlattice layer retains more periods and relatively thick wells / barriers to release stress on the first semiconductor layer, filter lattice defects, and provide a high-quality growth template for the upper layer; while the active layer has fewer quantum well layers than the superlattice layer, and fewer quantum barrier layers than the superlattice layer. That is, the active layer is designed with fewer periods than the superlattice layer, and its quantum well layer thickness is less than the quantum well layer thickness of the superlattice layer, and / or its quantum barrier layer thickness is less than the quantum barrier layer thickness of the superlattice layer. This short-period, thin-well / thin-barrier active layer concentrates injected carriers into a few extremely thin quantum wells, increasing the carrier concentration and electron-hole wave function overlap within the wells, thus accelerating the radiative recombination rate. Simultaneously, the thinned barrier layer shortens the interlayer transport time of carriers, effectively reducing the carrier recombination lifetime and improving the electro-response rate of the epitaxial material itself for active regions in high-speed optical communication epitaxy. This disclosure significantly improves the -3dB communication bandwidth and transmission rate of light-emitting devices. Furthermore, due to the increased carrier recombination efficiency and faster response speed, the device can achieve sufficient modulation bandwidth without high current, thereby significantly reducing power consumption and meeting the requirements of Micro LED optical interconnects for low power consumption and high bandwidth scalability. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this disclosure; Figure 2 This is a schematic diagram of the film layer of a light-emitting unit provided in an embodiment of this disclosure; Figure 3 This is a test comparison diagram of a light-emitting device provided in an embodiment of this disclosure; Figure 4 This is a flowchart of a method for fabricating a light-emitting device according to an embodiment of this disclosure.

[0018] The markings in the diagram are explained as follows: 10. Substrate; 20. Buffer layer; 30. First semiconductor layer; 40. Superlattice layer; 50. Active layer; 60. Second semiconductor layer; 100. Driving substrate; 101. Light-emitting unit; 102. First electrode; 103. Second electrode; 104. Bonding metal block; 105. Insulating layer; 106. Transparent conductive layer. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0020] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the element or object preceding “comprising” or “including” encompasses the element or object listed following “comprising” or “including” and its equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” “top,” and “bottom,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0021] Figure 1 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this disclosure. Figure 1 As shown, the light-emitting device includes a driving substrate 100 and a plurality of light-emitting units 101, with the plurality of light-emitting units 101 arranged at intervals on the driving substrate 100.

[0022] like Figure 1 As shown, each light-emitting unit 101 includes a first electrode 102, a second electrode 103, and a semiconductor stack.

[0023] Figure 2 This is a schematic diagram of the film layer of a light-emitting unit provided in an embodiment of this disclosure. For example... Figure 2 As shown, the semiconductor stack of the light-emitting unit 101 includes a first semiconductor layer 30, a superlattice layer 40, an active layer 50, and a second semiconductor layer 60 stacked sequentially.

[0024] like Figure 1 As shown, the first electrode 102 is electrically connected to the first semiconductor layer 30, and the second electrode 103 is electrically connected to the second semiconductor layer 60.

[0025] Both the superlattice layer 40 and the active layer 50 include multiple quantum well layers and multiple quantum barrier layers stacked alternately. The number of quantum well layers in the active layer 50 is less than the number of quantum well layers in the superlattice layer 40, and the number of quantum barrier layers in the active layer 50 is less than the number of quantum barrier layers in the superlattice layer 40. That is, the active layer 50 is designed to have a smaller number of periods than the superlattice layer 40.

[0026] The thickness of the quantum well layer of the active layer 50 is less than the thickness of the quantum well layer of the superlattice layer 40, and / or the thickness of the quantum barrier layer of the active layer 50 is less than the thickness of the quantum barrier layer of the superlattice layer 40.

[0027] In this embodiment of the disclosure, one of the first semiconductor layer and the second semiconductor layer is an n-type layer, and the other of the first semiconductor layer and the second semiconductor layer is a p-type layer.

[0028] For example, the first semiconductor layer 30 is an n-type layer and the second semiconductor layer 60 is a p-type layer.

[0029] like Figure 1 As shown, the light-emitting device also includes a plurality of bonding metal blocks 104, each corresponding to a light-emitting unit 101. The bonding metal blocks 104 are spaced apart on the driving substrate 100 and electrically connected to the driving substrate 100. The light-emitting unit 101 is located on the corresponding bonding metal block 104, and the bonding metal block 104 is attached to the first electrode 102 of the corresponding light-emitting unit 101.

[0030] like Figure 1As shown, the light-emitting device also includes an insulating layer 105 and a transparent conductive layer 106. The insulating layer 105 is located on the driving substrate 100 and covers each light-emitting unit 101. The insulating layer 105 is provided with a via that exposes the top light-emitting surface of each light-emitting unit 101. The transparent conductive layer 106 is located on the insulating layer 105 and is electrically connected to each light-emitting unit 101 through the via.

[0031] The second electrode 103 is located in the gap between adjacent light-emitting units 101 and on the transparent conductive layer 106, so that the circuit injected from the second electrode 103 can be simultaneously transmitted to each light-emitting unit 101 through the transparent conductive layer 106.

[0032] The light-emitting device provided in this disclosure splits the semiconductor stack into a superlattice layer 40 and an active layer 50 grown sequentially, both containing alternating quantum well layers and quantum barrier layers. The superlattice layer 40 retains more periods and relatively thick wells / barriers to release stress on the n-type layer, filter lattice defects, and provide a high-quality growth template for the upper layer. The active layer 50 is designed with fewer periods than the superlattice layer 40, and its quantum well layer thickness is less than that of the superlattice layer 40, and / or its quantum barrier layer thickness is less than that of the superlattice layer 40. This short-period, thin-well / thin-barrier active layer 50 concentrates injected carriers into a few extremely thin quantum wells, increasing the carrier concentration within the wells and the overlap of the electron-hole wave function, thus accelerating the radiative recombination rate. At the same time, the thinned barrier layer shortens the carrier transport time between layers, thereby effectively reducing the carrier recombination lifetime and improving the electrical response rate of the epitaxial material itself for the active region structure of high-speed optical communication epitaxy. This disclosure can significantly improve the -3dB communication bandwidth and transmission rate of light-emitting devices. Furthermore, due to the improved carrier recombination efficiency and faster response speed, the device can obtain sufficient modulation bandwidth without high current, thereby significantly reducing power consumption and meeting the requirements of Micro LED optical interconnects for low power consumption and high bandwidth scalability.

[0033] Optionally, the active layer 50 has 2 to 3 periods, and the superlattice layer 40 has 4 to 10 periods.

[0034] For superlattice layer 40, an alternating quantum well / barrier structure with 4 to 10 cycles is sufficient to form an effective stress release and defect filtering template on the n-type layer. Its appropriate thickness can smooth the interface and accommodate lattice mismatch, avoiding insufficient buffering and deterioration of the quality of the upper high-indium composition thin well crystal due to too few cycles. At the same time, this upper limit does not result in excessive stacking, preventing unnecessary increase in the total epitaxial thickness and waste of process costs.

[0035] For example, the number of periods in the superlattice layer 40 is 5.

[0036] For the active layer 50, its number of periods is strictly limited to 2 to 3. This design maximizes carrier concentration while ensuring the necessary optical output power (avoiding insufficient light emission from a single-period well, which would necessitate increasing the driving current). The limited number of wells allows injected carriers to be efficiently confined within an extremely thin quantum well, increasing the radiative recombination rate and shortening the recombination lifetime. Together, the superlattice layer 40 improves crystal growth quality with a larger number of periods, while the active layer 50 improves the radiative recombination rate with a very small number of periods.

[0037] For example, the number of cycles in the active layer 50 is 3.

[0038] Optionally, the thickness of the quantum well layer of the active layer 50 is 0.8 nm to 1.5 nm, and the thickness of the quantum barrier layer of the active layer 50 is 5 nm to 12 nm.

[0039] The sub-2 nanometer-scale ultrathin quantum well layer generates a strong quantum confinement effect, which makes the electron and hole wave functions highly overlapped, greatly improving the radiative recombination rate and thus shortening the carrier recombination lifetime, meeting the requirements of rapid switching of high-frequency signals.

[0040] Secondly, the thin quantum barrier layer of 5nm to 12nm reduces the physical distance and time for charge carriers to diffuse and traverse between different wells; and the overall thickness of the active region is reduced due to the thin wells and thin barriers, which reduces the parasitic capacitance of the Micro LED device and optimizes the RC time constant. Combined with the few-cycle design, this structure maximizes the electro-optical response rate while maintaining sufficient optical power.

[0041] Optionally, the thickness of the quantum well layer of the superlattice layer 40 is 3 nm to 6 nm, and the thickness of the quantum barrier layer of the superlattice layer 40 is 20 nm to 30 nm.

[0042] The thicker quantum well and quantum barrier layers can form a more relaxed lattice relaxation space, effectively absorbing and shielding dislocations and thermal mismatch stresses transmitted from the substrate 10 and the n-type layer, preventing defects from extending upwards. Simultaneously, this structure provides an atomically flat interface template for the subsequent growth of a high-In-content, extremely thin active layer 50, avoiding the surge of nonradiative recombination centers caused by directly growing thin wells on a high-defect surface, thus ensuring the luminous efficiency and reliability of the entire light-emitting device.

[0043] For example, the superlattice layer 40 includes eight periods of InGaN well layers and GaN barrier layers, with the InGaN well layers having a thickness of 4 nm and the GaN barrier layers having a thickness of 25 nm; the active layer 50 includes three periods of InGaN well layers and GaN barrier layers, with the InGaN well layers having a thickness of 1.2 nm and the GaN barrier layers having a thickness of 8 nm.

[0044] Optionally, the quantum well layers of the active layer 50 and the superlattice layer 40 are both InGaN layers, and the quantum barrier layers of the active layer 50 and the superlattice layer 40 are both GaN layers.

[0045] Among them, the In composition content of the quantum well layer of the active layer 50 is greater than that of the quantum well layer of the superlattice layer 40.

[0046] For the superlattice layer 40, controlling the In composition of the InGaN well layer to a relatively low level, combined with its thicker well / barrier dimensions, effectively avoids the severe lattice mismatch problem caused by high indium composition in thick films. The thick well structure with low In content has good crystal stability and can serve as a high-quality stress relief and defect filtering template, providing a flat and defect-free growth interface for the upper high-speed active layer 50, without generating a large number of non-radiative recombination centers due to its own In aggregation. This ensures the effective functioning of the buffer substrate and avoids efficiency collapse caused by defect penetration during subsequent thin well growth.

[0047] For the active layer 50, increasing the In composition of its InGaN well layer narrows the quantum well bandgap, enhancing the three-dimensional localization effect of charge carriers under the constraint of extremely thin well thickness, further intensifying the overlap of electron-hole wave functions, accelerating radiative recombination to shorten the recombination lifetime; at the same time, a step barrier between the conduction band and valence band is formed from the low In well of the superlattice layer 40 to the high In well of the active layer 50, which efficiently collects and confines the injected charge carriers in the thin well of the active layer 50 with high recombination capability, suppressing the overflow and leakage of charge carriers to the p-type side and improving the injection efficiency.

[0048] Optionally, the In content of the quantum well layer of the active layer 50 is 12% to 18%, and the In content of the quantum well layer of the superlattice layer 40 is 5% to 10%.

[0049] For the superlattice layer 40, the relatively low In content of 5%~10% combined with its thicker well layer (3~6nm) and thicker barrier layer (20~30nm) can provide stress gradient release and defect filtering while strictly avoiding crystal defects such as phase separation, indium clusters and V-shaped pits that are easily induced by high indium composition in thick films. This ensures the structural quality and interface flatness of the buffer layer 20 itself, which is conducive to the growth of a defect-free active layer 50.

[0050] For the active layer 50, the relatively high In content of 12%~18% increases the overlap integral of the electron-hole wave function, improves the radiative recombination probability and compresses the carrier recombination lifetime; at the same time, a significant bandgap is formed from the low indium wide well of the superlattice layer 40 to the high indium thin well of the active layer 50, which effectively suppresses carrier leakage to the p side and improves the injection efficiency.

[0051] For example, the In content of the quantum well layer of the superlattice layer 40 is 8%, and the In content of the quantum well layer of the active layer 50 is 15%.

[0052] Optionally, in two to three cycles of the active layer 50, the thickness of the quantum well layer decreases progressively from the direction near the superlattice layer 40 to the direction near the p-type layer, and / or the In composition increases progressively, while the thickness of the quantum barrier layer also decreases progressively.

[0053] The advantage of this gradual improvement is that it avoids the instantaneous accumulation of interfacial stress caused by a sudden jump in parameters between the superlattice layer 40 and the active layer 50 during the first cycle (thin-well high In). This allows carriers injected into the active region to first pass through a relatively mild confinement region before entering the high-velocity recombination region. While maintaining the ultra-short recombination lifetime of the final thin-well, it further reduces the probability of the through-dislocation extending into the light-emitting region. At the same time, the progressively increasing In composition forms a stepped conduction band step, continuously guiding electrons to the thin well closest to the p-side, improving carrier collection efficiency and uniformity, thus achieving higher bandwidth gain and lower leakage current compared to a uniform thin-well structure.

[0054] Optionally, the quantum barrier layer of the active layer 50 is Si-doped, and the Si doping concentration is 1×10⁻⁶. 17 cm -3 Up to 1×10 18 cm -3 .

[0055] In Micro LED devices, while the thin barrier (5nm to 12nm) and few-cycle design of the active layer 50 shorten carrier transport time, they also introduce risks of increased lateral resistance in the active region and exacerbated current congestion. Moderate Si doping improves the n-type conductivity of the quantum barrier layer, effectively reducing the equivalent series resistance of the active region, thereby decreasing the RC time constant of the device. This, combined with the short recombination lifetime resulting from the thin well, increases the -3dB communication bandwidth. Simultaneously, Si doping within this concentration range provides sufficient free electrons in the quantum barrier, partially shielding the polarization electric field in the InGaN high-indium thin well, alleviating band tilt, increasing the overlap of electron and hole wave functions, improving radiative recombination efficiency, and preventing carrier leakage to non-radiative recombination centers due to electric field separation.

[0056] Optionally, the quantum barrier layer furthest from the n-type layer in the active layer 50 is Mg-doped, and the Mg doping concentration is 1×10⁻⁶. 17 cm -3 Up to 1×10 18 cm -3 .

[0057] In Micro LED optical communication devices, when charge carriers are injected from the n-type layer and recombine rapidly through a few-period thin well to emit light, the interface adjacent to the p-type layer is prone to nonradiative recombination and efficiency loss due to electron overflow. This is especially true in quantum structures with high In composition and thin barrier layers, where high electron mobility allows them to easily penetrate the thin barrier into the p-region, causing light leakage and heat generation. Doping the last quantum barrier layer of the active layer 50 with Mg to give it p-type or weak p-type properties effectively increases the conduction band barrier to prevent electron leakage to the p-type layer. Simultaneously, it forms a homotype transition with the upper p-type layer, smoothing the valence band step and promoting uniform hole injection from the p-type layer into the active region's thin well.

[0058] Optionally, the thickness of the Mg-doped quantum barrier layer is greater than that of the other Si-doped quantum barrier layers in the active layer 50. For example, the thickness of the Mg-doped quantum barrier layer is 12 nm to 20 nm.

[0059] While changing the last layer to Mg doping can enhance valence band-assisted hole injection, if the thickness remains at 5nm to 12nm, the electron blocking barrier width will be insufficient, and high-speed electrons may still tunnel through and leak. Appropriately thickening the layer can form a more robust electron blocking layer, further reducing the overflow non-radiative current, thereby reducing the required driving voltage under the same optical power and enhancing the low-power effect.

[0060] Optionally, such as Figure 2 As shown, the light-emitting device also includes a substrate 10 and a buffer layer 20, with the buffer layer 20 located on the substrate 10 and the first semiconductor layer 30 (n-type layer) located on the buffer layer 20.

[0061] For example, the substrate 10 is sapphire, silicon, or patterned sapphire substrate 10.

[0062] For example, the buffer layer 20 includes at least one of an AlN layer and an AlGaN layer.

[0063] For example, the n-type layer includes an n-type GaN layer.

[0064] For example, the p-type layer includes a p-type GaN layer.

[0065] This disclosure provides a light-emitting device, which uses a patterned sapphire substrate 10 as a growth substrate, on which a buffer layer 20, an n-type layer, a superlattice layer 40, an active layer 50 and a p-type layer are sequentially stacked.

[0066] The buffer layer 20 is an AlN layer (or a composite layer of AlN and AlGaN) used to alleviate the lattice mismatch between the substrate 10 and the subsequent epitaxial layer and to block defect propagation. The n-type layer is an n-type GaN layer, and the p-type layer is a p-type GaN layer.

[0067] The superlattice layer 40 is designed as an 8-period InGaN / GaN superlattice structure. Its quantum well layers are all InGaN layers with a thickness of 4 nm and an In content of 8%, and its quantum barrier layers are all GaN layers with a thickness of 25 nm. The superlattice layer 40 mainly serves as a buffer for stress release and defect filtering.

[0068] The active layer 50 is designed as a three-period InGaN / GaN superlattice structure. Its quantum well layers are all InGaN layers with a thickness of 1.2 nm and an In content of 15%, while its quantum barrier layers are all GaN layers with a thickness of 8 nm.

[0069] Furthermore, all quantum barrier layers in the active layer 50, except for the last layer, are Si-doped (with a Si doping concentration of 5 × 10¹). 7 cm - ³), while the last quantum barrier layer in active layer 50, which is furthest from the n-type layer (i.e., the side immediately adjacent to the p-type layer), is replaced with Mg doping (Mg doping concentration is 1×10¹). 7 cm - ³).

[0070] The above example designs a light-emitting device for high-speed optical communication. Through the synergistic regulation of the superlattice layer 40 and the active layer 50, the recombination lifetime of the charge carriers is effectively reduced and the electrical response rate of the epitaxial material itself is improved.

[0071] Figure 3 This is a test comparison diagram of a light-emitting device provided in an embodiment of this disclosure. The light-emitting device grown using the above example was fabricated as a 20μm diameter circular, upright Micro LED chip for testing. Figure 3 As shown, a -3dB electro-optic (EO) bandwidth test was performed using a vector network analyzer. The bandwidth before improvement (i.e., a multi-quantum-well structure with 8 or more wide-wells / barriers) was 0.4 GHz, while the bandwidth after improvement (in the example above) reached 1.8 GHz. This disclosed embodiment significantly improves the bandwidth and transmission rate of the optical chip. Furthermore, due to the increased carrier recombination efficiency and reduced RC time constant, the device can achieve sufficient modulation bandwidth without high current, thereby significantly reducing power consumption.

[0072] Figure 4 This is a flowchart illustrating a method for fabricating a light-emitting device according to an embodiment of this disclosure. For example... Figure 4 As shown, the preparation method includes: Step S11: Grow a first semiconductor layer on the surface of the substrate.

[0073] First, a substrate is provided, and a buffer layer is grown on the substrate.

[0074] For example, the substrate may be sapphire, silicon, or a patterned sapphire substrate.

[0075] For example, the buffer layer includes at least one of an AlN layer and an AlGaN layer.

[0076] The buffer layer is located on the substrate and is used to mitigate lattice mismatch and block dislocations.

[0077] For example, the first semiconductor layer is an n-type layer.

[0078] Then, an n-type layer is grown on the surface of the buffer layer.

[0079] For example, the n-type layer includes an n-type GaN layer, which is formed on the surface of the buffer layer by epitaxial deposition as a negative electrode contact basis for carrier injection.

[0080] Step S12: Grow a superlattice layer on the first semiconductor layer.

[0081] For example, the superlattice layer comprises alternating layers of quantum wells and quantum barrier layers, with a period number of 4 to 10.

[0082] The quantum well layers are all InGaN layers with a thickness of 3nm to 6nm and an In content controlled at 5% to 10%. The quantum barrier layers are all GaN layers with a thickness of 20nm to 30nm. This superlattice layer mainly serves the functions of stress release and defect filtering, providing a flat and defect-free growth template for the high-speed active region above.

[0083] Step S13: Grow an active layer on the superlattice layer.

[0084] The active layer comprises multiple alternating quantum well layers and multiple quantum barrier layers; the number of periods of the active layer is less than the number of periods of the superlattice layer, the thickness of the quantum well layer of the active layer is less than the thickness of the quantum well layer of the superlattice layer, and / or the thickness of the quantum well barrier of the active layer is less than the thickness of the quantum barrier layer of the superlattice layer.

[0085] For example, the number of periods in the active layer is 2 to 3, which is less than the number of periods in the superlattice layer.

[0086] For example, the quantum well layer of the active layer is an InGaN layer with a thickness reduced to 0.8 nm to 1.5 nm and an In content increased to 12% to 18%. The thickness of the quantum well layer of the active layer is smaller than that of the quantum well layer of the superlattice layer.

[0087] For example, the quantum barrier layer of the active layer is a GaN layer with a thickness reduced to 5 nm to 12 nm. The thickness of the quantum barrier layer of the active layer is smaller than the thickness of the quantum barrier layer of the superlattice layer.

[0088] The quantum barrier layer in the active layer is doped with Si at a concentration of 1×10¹. 7 cm- ³ to 1×10¹ 8 cm - ³; and the quantum barrier layer furthest from the n-type layer in the active layer is replaced with Mg-doped, with a Mg doping concentration of 1×10¹. 7 cm - ³ to 1×10¹ 8 cm - ³. This design, featuring fewer cycles, thin wells and thin barriers, and high indium composition, enables the active layer to achieve a short recombination lifetime and a high electro-optic response rate.

[0089] Step S14: Grow a second semiconductor layer on the active layer.

[0090] For example, the second semiconductor layer is a p-type layer, which includes a p-type GaN layer that covers the last Mg-doped quantum barrier of the active layer, thus completing the overall epitaxial wafer stack-up structure.

[0091] Step S15: Form the first electrode and the second electrode.

[0092] The first electrode is electrically connected to the first semiconductor layer, and the second electrode is electrically connected to the second semiconductor layer.

[0093] The light-emitting device fabricated using the above method divides the active region into sequentially grown superlattice layers and active layers, both containing alternating quantum well layers and quantum barrier layers. The superlattice layer retains more periods and relatively thick well / barrier layers to release stress on the n-type layer, filter lattice defects, and provide a high-quality growth template for the upper layers. The active layer is designed with fewer periods than the superlattice layer, and its quantum well layer thickness is less than that of the superlattice layer's quantum well layer, and / or its quantum barrier layer thickness is less than that of the superlattice layer's quantum barrier layer. This short-period, thin-well / thin-barrier active layer concentrates injected carriers into a few extremely thin quantum wells, increasing the carrier concentration within the wells and the overlap of the electron-hole wave function, thus accelerating the radiative recombination rate. At the same time, the thinned barrier layers shorten the carrier transport time between layers, thereby effectively reducing the carrier recombination lifetime and improving the electrical response rate of the epitaxial material itself for the active region structure of high-speed optical communication epitaxy. This disclosure can significantly improve the -3dB communication bandwidth and transmission rate of light-emitting devices. Furthermore, due to the improved carrier recombination efficiency and faster response speed, the device can obtain sufficient modulation bandwidth without high current, thereby significantly reducing power consumption and meeting the requirements of Micro LED optical interconnects for low power consumption and high bandwidth scalability.

[0094] This disclosure provides an optical communication device. The optical communication device includes a substrate, an optical fiber, and a plurality of light-emitting devices as described above, the light-emitting devices being arranged at intervals on the substrate.

[0095] The substrate can be an epitaxial growth substrate such as sapphire or silicon, or a transposed substrate (such as a silicon or copper high thermal conductivity substrate) used through bonding or mass transfer processes.

[0096] For example, multiple light-emitting devices are arranged in an array, such as by first fabricating multiple rows of separate cores on the substrate surface and then cutting and separating them, or flip-chip transferring them onto the substrate to present a uniform distribution.

[0097] The epitaxial wafer of a light-emitting device comprises an n-type layer, a superlattice layer, an active layer, and a p-type layer stacked sequentially.

[0098] Epitaxial wafers can be grown using an MOCVD system to create GaN / InGaN systems. Then, through semiconductor planar processes such as etching and isolation, transparent electrode deposition, and possible substrate stripping, they can be fabricated into micro-chips. This allows the measured -3dB electro-optic bandwidth of the fabricated 20μm diameter chip to jump from 0.4GHz to 1.8GHz, significantly improving the transmission rate while reducing power consumption.

[0099] The above is not intended to limit this disclosure in any way. Although this disclosure has been disclosed above through embodiments, it is not intended to limit this disclosure. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this disclosure. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this disclosure without departing from the content of the technical solution of this disclosure shall still fall within the scope of the technical solution of this disclosure.

Claims

1. A light-emitting device, characterized in that, The light-emitting device includes a plurality of light-emitting units (101), each of the light-emitting units (101) including a first electrode (102), a second electrode (103) and a semiconductor stack; The semiconductor stack includes a first semiconductor layer (30), a superlattice layer (40), an active layer (50), and a second semiconductor layer (60) stacked sequentially. The first electrode is electrically connected to the first semiconductor layer (30), and the second electrode is electrically connected to the second semiconductor layer (60). Both the superlattice layer (40) and the active layer (50) include multiple quantum well layers and multiple quantum barrier layers stacked alternately; The number of quantum well layers in the active layer (50) is less than the number of quantum well layers in the superlattice layer (40), and the number of quantum barrier layers in the active layer (50) is less than the number of quantum barrier layers in the superlattice layer (40). The thickness of the quantum well layer of the active layer (50) is less than the thickness of the quantum well layer of the superlattice layer (40), and / or the thickness of the quantum barrier layer of the active layer (50) is less than the thickness of the quantum barrier layer of the superlattice layer (40).

2. The light-emitting device according to claim 1, characterized in that, The thickness of the quantum well layer of the active layer (50) is 0.8 nm to 1.5 nm, and the thickness of the quantum barrier layer of the active layer (50) is 5 nm to 12 nm.

3. The light-emitting device according to claim 2, characterized in that, The thickness of the quantum well layer of the superlattice layer (40) is 3 nm to 6 nm, and the thickness of the quantum barrier layer of the superlattice layer (40) is 20 nm to 30 nm.

4. The light-emitting device according to any one of claims 1 to 3, characterized in that, The number of periods of the active layer (50) is 2 to 3, and the number of periods of the superlattice layer (40) is 4 to 10.

5. The light-emitting device according to claim 4, characterized in that, The quantum well layers of the active layer (50) and the superlattice layer (40) are both InGaN layers, and the quantum barrier layers of the active layer (50) and the superlattice layer (40) are both GaN layers. The In content of the quantum well layer of the active layer (50) is greater than the In content of the quantum well layer of the superlattice layer (40).

6. The light-emitting device according to claim 5, characterized in that, The In content of the quantum well layer of the active layer (50) is 12% to 18%, and the In content of the quantum well layer of the superlattice layer (40) is 5% to 10%.

7. The light-emitting device according to claim 4, characterized in that, The quantum barrier layer of the active layer (50) is Si-doped, and the Si doping concentration is 1×10⁻⁶. 17 cm -3 Up to 1×10 18 cm -3 .

8. The light-emitting device according to claim 7, characterized in that, The quantum barrier layer furthest from the first semiconductor layer (30) in the active layer (50) is Mg-doped, and the Mg doping concentration is 1×10⁻⁶. 17 cm -3 Up to 1×10 18 cm -3 .

9. An optical communication device, characterized in that, The optical communication device includes an optical fiber and a light-emitting device as described in any one of claims 1 to 8.

10. A method for fabricating a light-emitting device, characterized in that, The preparation method includes: A first semiconductor layer (30) is grown on the surface of the substrate (10). A superlattice layer (40) is grown on the first semiconductor layer (30); An active layer (50) is grown on the superlattice layer (40). Both the superlattice layer (40) and the active layer (50) include alternating layers of multiple quantum well layers and multiple quantum barrier layers. The number of quantum well layers in the active layer (50) is less than the number of quantum well layers in the superlattice layer (40), the number of quantum barrier layers in the active layer (50) is less than the number of quantum barrier layers in the superlattice layer (40), the thickness of the quantum well layers in the active layer (50) is less than the thickness of the quantum well layers in the superlattice layer (40), and / or the thickness of the quantum well barriers in the active layer (50) is less than the thickness of the quantum barrier layers in the superlattice layer (40). A second semiconductor layer (60) is grown on the active layer (50); A first electrode and a second electrode are formed, wherein the first electrode is electrically connected to the first semiconductor layer (30) and the second electrode is electrically connected to the second semiconductor layer (60).

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