Micro-led pixel-level collimation structure based on cooperation modulation of v-pit and superlens

Abstract

The present application relates to the technical field of Micro-LED, and particularly relates to a Micro-LED pixel-level collimation structure based on V-pit and superlens cooperative modulation. The collimation structure comprises a pixel-level collimation superlens, a Micro-LED pixel structure and a patterned substrate. The pixel-level collimation superlens comprises a superlens substrate and a plurality of nanometer pillars arranged on the superlens substrate; the Micro-LED pixel structure contains a V-pit, which guides the recombination and light emission of carriers in the V-pit area; the patterned substrate is attached to the Micro-LED pixel structure, and the patterned substrate is formed with a protrusion, and the protrusion is arranged opposite to the V-pit. The present application introduces the V-pit into the Micro-LED pixel structure, thereby realizing the local light emission of the light source while modulating the photon distribution and improving the light extraction efficiency, and the pixel-level collimation superlens with a specific design outside the light source can realize the pixel-level collimation of the Micro-LED with the minimum size of microns, effectively solving the problems of poor Micro-LED pixel-level collimation effect, complex process preparation, low light extraction efficiency, low light emission uniformity and the like, and having important theoretical and application values.

Description

Technical Field

[0001] This invention relates to the field of Micro-LED technology, and in particular to a Micro-LED pixel-level collimation structure based on the synergistic modulation of V-pits and superlenses. Background Technology

[0002] Micro-LED (micro-light-emitting diode) is a self-emissive display technology based on inorganic light-emitting diodes. As an incoherent surface light source, it generates photons through the spontaneous emission of multiple independent electron-hole pairs. Compared to traditional OLED or LCD technologies, its pixel size can be reduced to the micrometer scale (typically less than 50μm), offering advantages such as high brightness, high contrast, fast response time, and low power consumption, making it an important development direction for next-generation display technology. Micro-LEDs exhibit an approximate Lambertian light field distribution with a divergence angle as high as 120°, resulting in low luminous efficiency, which limits its application in compact optical systems such as AR / VR and automotive displays. Micro-LED pixel-level collimation refers to the precise control of the beam direction of each individual pixel, significantly reducing its divergence angle. Developing integrated, high-efficiency Micro-LED pixel-level collimation solutions is of great significance for enhancing luminous efficiency, improving display quality, promoting the miniaturization of optical systems, and expanding application scenarios in multiple fields such as optical communication.

[0003] Currently, the mainstream solution for pixel-level light collimation in Micro-LEDs is a microlens array. This involves integrating micron-sized lenses (such as hemispherical or aspherical structures) corresponding to each pixel onto the surface of the Micro-LED, thereby compressing the divergence angle and controlling the light pattern. However, this technology has the following significant drawbacks:

[0004] 1. Complex processing flow and poor process compatibility: Microlenses need to be fabricated through processes such as photolithography and thermal reflow, which are complex processes. In addition, there is a thermal expansion mismatch with the low-temperature bonding process of Micro-LED, which affects the integration yield.

[0005] 2. Low light extraction efficiency: Due to limitations in size and shape, the numerical aperture of microlenses is generally low (<0.7), directly affecting the light-receiving angle of the microlens towards the light source. Furthermore, the inherent curved surface structure also causes light reflection from the sidewalls, affecting light extraction efficiency.

[0006] 3. Limited collimation performance of surface light source: Since actual Micro-LEDs do not meet the approximate conditions of point light sources (especially in the case of low pixel pitch), the collimation performance of microlenses for pixels is greatly reduced. Currently, it can only achieve a collimation angle of ±20°, which is not suitable for application scenarios that require high luminous efficiency, low pixel crosstalk, and high resolution. Summary of the Invention

[0007] This invention provides a Micro-LED pixel-level collimation structure based on the synergistic modulation of V-pits and superlenses, which solves the defects of poor collimation performance, low light efficiency and low integration in existing Micro-LED pixel-level collimating lenses.

[0008] This invention provides a Micro-LED pixel-level collimation structure based on V-groove and superlens synergistic modulation, comprising:

[0009] Pixel-level collimating superlenses, including:

[0010] Superlens substrate;

[0011] Multiple nanopillars are disposed on the superlens substrate;

[0012] A micro-LED pixel structure is attached to one side of the superlens substrate. The micro-LED pixel structure forms a V-shaped pit, which extends in the opposite direction to the pixel-level collimating superlens. A light source is provided in the V-shaped pit.

[0013] A patterned substrate is attached to one side of the Micro-LED pixel structure opposite to the superlens substrate. The patterned substrate has protrusions that are positioned opposite to the V-pits.

[0014] According to the Micro-LED pixel-level collimation structure based on V-pit and superlens synergistic modulation provided by the present invention, multiple nanopillars form a nanopillar array, and multiple nanopillar arrays are disposed on a superlens substrate.

[0015] According to the Micro-LED pixel-level collimation structure based on V-pit and superlens synergistic modulation provided by the present invention, multiple Micro-LED pixel structures are provided, each Micro-LED pixel structure contains a V-pit, and each V-pit is correspondingly provided with a nanopillar array.

[0016] According to the Micro-LED pixel-level collimation structure based on V-pit and superlens synergistic modulation provided by the present invention, the nanopillars are silicon nitride nanopillars or titanium oxide nanopillars.

[0017] The Micro-LED pixel-level collimation structure based on V-pit and superlens synergistic modulation provided by the present invention includes a transparent conductive layer, a P-type gallium nitride layer, a multiple quantum well layer and an N-type gallium nitride layer stacked sequentially.

[0018] According to the Micro-LED pixel-level collimation structure based on V-pit and superlens synergistic modulation provided by the present invention, the patterned substrate includes a patterned sapphire substrate.

[0019] According to the Micro-LED pixel-level collimation structure based on V-pit and superlens synergistic modulation provided by the present invention, the protrusions on the patterned substrate are semi-circular protrusions or conical protrusions.

[0020] This invention provides a Micro-LED pixel-level collimation structure based on the synergistic modulation of V-pits and a superlens. The Micro-LED pixel-level collimation structure includes: a pixel-level collimating superlens, a Micro-LED pixel structure, and a patterned substrate. The pixel-level collimating superlens includes: a superlens substrate and multiple nanopillars. The multiple nanopillars are disposed on the superlens substrate; the Micro-LED pixel structure is attached to one side of the superlens substrate, and the Micro-LED pixel structure contains V-pits that guide carrier recombination and light emission in the V-pit region. The V-pits extend in the opposite direction to the pixel-level collimating superlens, and a light source is disposed within the V-pits; the patterned substrate is attached to the side of the Micro-LED pixel structure opposite to the superlens substrate, and the patterned substrate has protrusions that are positioned opposite to the V-pits. This invention introduces V-pits within the Micro-LED pixel structure, thereby modulating photon distribution and improving light extraction efficiency while achieving localized light emission from the light source. Combined with a specially designed pixel-level collimating superlens outside the light source, it can achieve pixel-level collimation for Micro-LEDs with a minimum size of a few micrometers. This effectively solves the problems of poor pixel-level collimation, complex fabrication process, low light extraction efficiency, and low light emission uniformity in existing Micro-LEDs, and has significant theoretical and application value. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a Micro-LED pixel-level collimation structure based on V-pit and superlens co-modulation provided in one embodiment of the present invention.

[0023] Figure 2 This is an exploded view of the Micro-LED pixel-level collimation structure based on V-pit and superlens co-modulation provided in one embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the structure of a pixel-level collimating superlens and a Micro-LED pixel structure forming an array provided in one embodiment of the present invention.

[0025] Figure 4 This is an FDTD simulation diagram of a Micro-LED pixel structure with V-pits provided in one embodiment of the present invention.

[0026] Figure 5 This is a schematic diagram of the light field propagation at the V-shaped pit provided in one embodiment of the present invention.

[0027] Figure 6 This is the emission angle spectrum of a Micro-LED pixel structure containing V-pits provided in one embodiment of the present invention.

[0028] Figure 7 This is a simulation structure diagram of a Micro-LED pixel-level collimation structure based on V-pit and superlens co-modulation provided in one embodiment of the present invention.

[0029] Figure 8 This is a simulated emission angle spectrum of a Micro-LED pixel-level collimation structure based on V-pit and superlens co-modulation provided in one embodiment of the present invention.

[0030] Figure 9 This is a collimation effect diagram of the superlens without introducing V-pit cooperative modulation in the existing technology.

[0031] Figure label:

[0032] 1: Pixel-level collimating superlens; 2: Micro-LED pixel structure; 3: Patterned substrate; 4: V-pit; 5: Light source. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] In the description of this embodiment, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this embodiment and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this embodiment.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this embodiment, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0036] In this embodiment, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this embodiment based on the specific circumstances.

[0037] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0038] The following is combined with Figures 1-8 This invention describes a Micro-LED pixel-level collimation structure based on the synergistic modulation of V-pits and a superlens. The Micro-LED pixel-level collimation structure includes: a pixel-level collimating superlens 1, a Micro-LED pixel structure 2, and a patterned substrate 3.

[0039] The pixel-level collimating superlens 1 includes a superlens substrate and multiple nanopillars. The nanopillars are disposed on the superlens substrate. A Micro-LED pixel structure 2 is attached to one side of the superlens substrate. The Micro-LED pixel structure 2 contains V-pits 4, which guide carriers in the light-emitting layer to recombine and emit light in the V-pit region (as a light source 5). The V-pits 4 extend in the opposite direction to the pixel-level collimating superlens 1, and the light source 5 is disposed within the V-pits 4. A patterned substrate 3 is attached to one side of the Micro-LED pixel structure 2 away from the superlens substrate. The patterned substrate 3 has protrusions that are positioned opposite to the V-pits 4.

[0040] V-pits (V-pits) are inverted pyramidal surface microstructures formed during the epitaxial growth of Micro-LEDs due to crystal defects (such as screw dislocations). They are commonly found in the epitaxial layers of GaN-based materials (gallium nitride-based materials). Introducing V-pit structures into light source 5 can effectively avoid QCSE (quantum Stark confinement effect) and improve carrier recombination rate. Furthermore, V-pits have high space utilization, providing a larger semi-polar surface area compared to planar structures, effectively improving the EQE (internal quantum efficiency) of light source 5. However, excessive V-pits can cause device performance degradation or even failure. Therefore, by controlling epitaxial growth parameters (such as temperature, gas flow rate, and velocity) and material stress (caused by lattice mismatch or differences in thermal expansion coefficients), the number and distribution of V-pits can be controlled to some extent. This allows for the generation of multi-wavelength emission using their polycrystalline characteristics and improvement of EQE and light extraction efficiency at high current densities. Metasurfaces are planar two-dimensional metamaterials with subwavelength thickness, allowing for flexible control over the degrees of freedom of electromagnetic waves, such as amplitude, phase, dispersion, momentum, and polarization. Metalens, formally known as meta-lenses or metasurface structure lenses, are optical metasurfaces that enable lens imaging. They can locally modulate parameters such as the phase of incident light through the combination and arrangement of subwavelength artificial structures, forming a phase distribution corresponding to the focusing wavefront, thereby achieving the lens's focusing, collimating, or imaging functions. Metalens are ultralight and ultrathin planar structures. Currently, large-scale, high-quality fabrication of metalens can be achieved using methods such as nanoimprinting, further reducing the fabrication cost of metalenzantzantz arrays. They have significant application potential in the miniaturization, intelligentization, and integration of optoelectronic devices and optical systems.

[0041] Specifically, the pixel-level collimating superlens 1 consists of two parts: a superlens substrate and nanopillars. The superlens substrate plays a supporting and connecting role and is generally made of silicon oxide material. However, the nanopillars on the substrate are responsible for phase modulation and collimation. Multiple nanopillars of different diameters are evenly distributed on the superlens substrate.

[0042] The Micro-LED pixel structure 2 can be structurally adjusted according to actual conditions, but the dimensions of the pixel-level collimating superlens 1, the Micro-LED pixel structure 2, and the patterned substrate 3 should be matched. Taking GaN-based Micro-LED as an example, the pixel size is 5~50 micrometers. From top to bottom, it is mainly composed of four parts: ITO (Indium Tin Oxide), p-GaN (p-type gallium nitride), MQW (Multiple Quantum Wells), and n-GaN (n-type gallium nitride). Among them, MQW is a multi-quantum well layer composed of InGaN (indium gallium nitride) and GaN (gallium nitride). Charge carriers recombine in the MQW layer and emit photons.

[0043] The V-pit structure is located in the Micro-LED pixel structure 2. It is introduced due to the growth and positioning of the patterned substrate 3. It is generally evenly distributed in the center of each pixel. Each pixel contains only one V-pit 4. The size of the V-pit 4 accounts for about 10% to 50% of the pixel size.

[0044] On the one hand, the V-pit structure provides a tilted semi-polar surface, increasing the surface area of ​​the MQW while guiding more charge carriers to recombine in the V-pit 4 region (at the MQW layer location) through a built-in electric field. At this point, the V-pit 4 region emits a higher proportion of light compared to the c-surface region (i.e., the flat area in the MQW layer) surrounding V-pit 4, forming a "localized emission" phenomenon. This allows the original surface light source to be equivalent to a point light source, facilitating collimation by the external superlens. On the other hand, since the emission wavelength of the semi-polar surface differs from that of the c-surface, the external superlens can be specially designed according to the emission wavelength of V-pit 4, further increasing the extraction and collimation ratio of the central region of the light source 5, thereby achieving synergistic modulation of V-pit 4 and the superlens. It is understood that in the following embodiments, "c-surface" refers to the flat area surrounding V-pit 4. In this art, conventional polar GaN-based LEDs typically use 0001-plane sapphire as the substrate; therefore, the growth surface of the LED is the c-surface, also known as the polar surface.

[0045] The patterned substrate 3 can be made of sapphire (Al2O3), also known as a patterned sapphire substrate (PSS). The upper surface of the patterned substrate 3 has protrusions, the shape of which is not limited; they can be circular, conical, etc. These protrusions are mainly used for growing GaN epitaxial layers, and periodically arranged V-pits 4 are introduced within them. The vertical positions of the V-pits 4 correspond to the protrusion structures on the patterned substrate 3. It can be understood that the corresponding arrangement of the V-pits 4 and protrusions means that they are in the same horizontal position, i.e., the V-pits 4 are opposite to the protrusions.

[0046] The implementation principle of the above structure is roughly as follows:

[0047] A Micro-LED pixel structure 2 containing V-pits 4 is epitaxially grown from a patterned substrate 3, thereby changing the light pattern of the Micro-LED from a surface light source to an approximate point light source concentrated in the V-pits 4. A pixel-level collimating superlens 1 of corresponding design is fabricated above the pixel to achieve pixel collimation. The horizontal distribution position of the V-pits 4 can be specially customized by the PSS pattern, and is generally distributed at the exact center of the pixel.

[0048] This invention provides a Micro-LED pixel-level collimation structure based on the synergistic modulation of V-pits and a superlens, comprising: a pixel-level collimating superlens 1, a Micro-LED pixel structure 2, and a patterned substrate 3. The pixel-level collimating superlens 1 includes: a superlens substrate and multiple nanopillars. The multiple nanopillars are disposed on the superlens substrate; the Micro-LED pixel structure 2 is attached to one side of the superlens substrate, forming a V-pit 4, which extends in the opposite direction to the pixel-level collimating superlens 1, and a light source 5 is disposed within the V-pit 4; the patterned substrate 3 is attached to the side of the Micro-LED pixel structure 2 opposite to the superlens substrate, and the patterned substrate 3 has protrusions that are opposite to the V-pits 4. This invention introduces a V-pit 4 within the Micro-LED pixel structure 2, thereby achieving localized emission of the light source 5 while modulating photon distribution and improving light extraction efficiency. Combined with a specially designed pixel-level collimating superlens 1 outside the light source 5, pixel-level collimation of Micro-LEDs with a minimum size of a few micrometers can be achieved. This effectively solves the problems of poor pixel-level collimation effect, complex process fabrication, low light extraction efficiency, and low light emission uniformity of existing Micro-LEDs, and has important theoretical and application value.

[0049] In one embodiment of the present invention, such as Figure 3 In the structure shown, multiple nanopillars form a nanopillar array, and multiple nanopillar arrays are disposed on a superlens substrate. Correspondingly, multiple Micro-LED pixel structures 2 are disposed, each Micro-LED pixel structure 2 containing a V-pit 4, and each V-pit 4 corresponds to one nanopillar array. In this embodiment, the V-pits 4 are uniformly distributed at the center of each pixel, and a single pixel corresponds to only one V-pit 4 at its center position. The periodically distributed V-pits 4 improve the pixel light pattern, enhance light extraction efficiency, and improve the overall luminous uniformity of the Micro-LED array. Figure 3 In the structure shown, a corresponding nanopillar array is set on the superlens substrate by setting a Micro-LED pixel structure 2 and setting a V-pit at the center of each Micro-LED pixel structure 2.

[0050] In one embodiment of the present invention, the nanopillars are silicon nitride nanopillars or titanium oxide nanopillars. The design parameters of the nanopillars are related to the actual wavelength of the Micro-LED. Taking a Micro-LED with a center wavelength of 470nm and an FWHM (full width at half maximum) of 30nm as an example, the designed nanopillar height is 1200nm, the radius ranges from 60nm to 160nm, and the distance between two adjacent nanopillars is 450nm. The size of the superlens and the number of nanopillars can be adjusted according to the actual Micro-LED array requirements. The size of the superlens is generally equivalent to the pixel period. The superlens substrate is generally a visible light transparent material such as silicon oxide, which is directly grown on the upper layer of the Micro-LED pixel structure 2, and its thickness is related to the designed focal length of the superlens.

[0051] In one embodiment of the present invention, the Micro-LED pixel structure 2 includes a transparent conductive layer, a p-type gallium nitride layer (i.e., p-GaN), a multiple quantum well layer (i.e., MQW), and an N-type gallium nitride layer (i.e., n-GaN) stacked sequentially. Preferably, the transparent conductive layer can be an indium tin oxide layer (i.e., ITO). In this embodiment, taking a GaN-based Micro-LED as an example, the pixel size is 5~50 micrometers, and it is mainly composed of four parts from top to bottom: ITO, p-GaN, MQW, and n-GaN. The MQW is a multiple quantum well layer composed of InGaN and GaN, where charge carriers recombine and emit photons.

[0052] In one embodiment of the present invention, the patterned substrate 3 includes a patterned sapphire substrate (i.e., PSS) with periodically arranged hemispherical or conical protrusions on its surface, mainly used for growing GaN epitaxial layers, and periodically arranged V-pits 4 are introduced therein, wherein the vertical position of the V-pits 4 corresponds to the protrusion structure of the PSS.

[0053] In one embodiment of the present invention, the protrusions on the patterned substrate 3 are semi-circular protrusions or conical protrusions. Of course, other forms of protrusion structures may also be used depending on the actual situation.

[0054] This invention discloses a method for fabricating a pixel-level collimation structure for Micro-LEDs based on the synergistic modulation of V-pits and superlenses. The fabrication method specifically includes the following steps:

[0055] After epitaxially growing n-type gallium nitride on a patterned substrate 3 to obtain a V-pit 4 structure, a multi-quantum well layer, a p-type gallium nitride layer and a transparent conductive layer are grown sequentially to form a Micro-LED pixel structure 2.

[0056] A visible-light transparent superlens substrate is grown on top of the Micro-LED pixel structure 2, and a pixel-level collimating superlens 1 is obtained by etching nanopillars.

[0057] The present invention provides a method for fabricating a Micro-LED pixel-level collimation structure based on the synergistic modulation of V-pits and superlenses. The Micro-LED pixel-level collimation structure fabricated by the method has the same beneficial effects as those described in the above embodiments.

[0058] According to the above-described Micro-LED pixel-level collimation structure based on V-pit and superlens synergistic modulation of the present invention, the principle of the related structure and simulation results are explained, including three parts:

[0059] (1) A V-pit structure is introduced at a specific position in the source using PSS to achieve localized and efficient light emission of Micro-LED; (2) A collimating superlens is designed according to a specific light pattern; (3) The superlens is integrated with the Micro-LED containing V-pit 4 to achieve pixel-level collimation of the light source 5 with internal and external coordination.

[0060] 1. Localized emission is achieved by introducing a V-shaped pit structure.

[0061] One of the core aspects of device operation is the introduction of a uniform V-pit structure at the center (or a specific location) of each Micro-LED pixel structure 2. V-pit 4 is an inverted pyramid-shaped micro / nano structure in the epitaxial layer of GaN-based Micro-LEDs, and its formation is closely related to crystal defects and epitaxial growth conditions. During the epitaxial growth of GaN material on a heterogeneous substrate (such as sapphire), high-density dislocations (such as screw dislocations) are generated at the interface due to lattice mismatch and differences in thermal expansion coefficients. These dislocations become stress concentration points during subsequent growth, causing local collapse of the GaN crystal along the 0001 direction (i.e., the c-axis), forming an inverted pyramid-shaped V-pit structure. In metal-organic chemical vapor deposition (MOCVD), the surface mobility of GaN can be affected by controlling the III / V source ratio, growth temperature, and reaction chamber pressure, thereby influencing the formation rate and surface morphology of V-pit 4. However, it is difficult to introduce V-pit structures of specific size, location, and number in Micro-LEDs simply by controlling epitaxial growth conditions.

[0062] Microstructures can be induced on the GaN surface through etching, epitaxial growth, and other techniques to expose various types of non-polar / semi-polar surfaces beyond the polar planes, thus generating V-shaped pit structures. Currently, the most basic methods include catalyst-induced growth and selective-area growth (SAG). This invention uses the SAG method to grow V-shaped pit structures. The light emission of a Micro-LED containing V-shaped pit structures is simulated using the finite-difference time-domain (FDTD) method. The simulation results are as follows: Figures 4 to 6 As shown, Figure 4 This is the FDTD simulation structure diagram; Figure 5 This is a schematic diagram of the light field propagation at four points in the V-shaped pit; Figure 6This is the emission angle spectrum of Micro-LED pixel structure 2 containing V-pit 4. The blue line and green line represent the angular spectrum distribution of light emitted from V-pit 4 and c-surface, respectively. According to experimental data, the center wavelength of light emitted from V-pit 4 is 450nm, and the center wavelength of light emitted from c-surface is 530nm.

[0063] Based on the above simulation results, the Micro-LED light pattern containing V-pit 4 has the following three characteristics: (1) V-pit 4 dominates the light emission of Micro-LED (about 60%) compared to the c-plane; (2) V-pit 4 forms a ring-like light pattern (the angular peak is about 10 degrees); (3) V-pit 4 emits a different wavelength than the c-plane.

[0064] The dominance of V-pit 4 emission is due to the larger surface area of ​​the V-pit 4 slope, which generates a built-in electric field that guides carriers to flow from the c-plane to the V-pit 4, resulting in a higher carrier distribution on the V-pit 4 sidewalls. Furthermore, due to the high refractive index of semiconductor materials (e.g., n≈2.5 for GaN), the photon escape cone at the V-pit 4 sidewalls can reach over 60° compared to the 30° photon escape cone at the c-plane, leading to higher internal quantum efficiency. Actual efficiency can be further improved by optimizing the Micro-LED structure, epitaxial layer growth conditions, and V-pit 4 control parameters.

[0065] The main reason for the ring-shaped emission pattern in the region corresponding to V-pit 4 is that the difference in refractive index between the materials on both sides of V-pit 4 and the MQW layer leads to the formation of a waveguide-like structure at the sidewalls, guiding light along the sidewall direction and ultimately emitting it from the top corner of V-pit 4, forming a ring-shaped emission pattern. Furthermore, the numerous defects at the bottom of V-pit 4 cause more charge carriers to recombine in the upper part of the sidewalls, further forming the special ring-like light pattern. The actual light pattern and emission area can be specially designed and controlled according to the location and size of V-pit 4.

[0066] The reason why the emission wavelength of V-pit 4 differs from that of the c-face is that the growth rates of the sidewalls and the c-face are inconsistent, resulting in different thickness distributions in different regions of the MQW multilayer film structure, which in turn affects the emission wavelength. In this invention, the measured center wavelength of emission from V-pit 4 is 450 nm, and the center wavelength of emission from the c-face is 530 nm. The actual wavelength can be adjusted according to specific applications.

[0067] In summary, by strategically introducing V-pits 4 within the Micro-LED pixel structure 2, most photons can be concentrated and emitted from the V-pit 4 region, creating a localized light-emitting effect. In this case, the actual light-emitting area can be approximated as a point light source relative to the overall size of the Micro-LED, helping to reduce the design complexity of subsequent optical systems. Furthermore, introducing V-pits 4 not only improves the light pattern but also effectively enhances internal quantum efficiency and introduces multi-wavelength emission, laying the foundation for color displays.

[0068] 2. Pixel-level collimating superlens design

[0069] The collimating superlens is specially designed based on the actual light pattern and wavelength of the emission from the V-pit 4. Since the V-pit 4 is introduced into the light source 5 to achieve localized emission, it can be approximated as a point light source. In this case, it is only necessary to optimize the collimating superlens for the emission wavelength of the V-pit 4.

[0070] 3. Integrating the pixel-level collimating superlens 1 with the Micro-LED pixel structure 2 containing the V-shaped pit 4 achieves pixel-level collimation with coordinated internal and external light source 5.

[0071] The key to the Micro-LED pixel-level collimation scheme proposed in this invention is the coordinated modulation of the source-internal V-pit 4 and the external superlens to jointly achieve functions such as beam pattern optimization and light efficiency improvement. Its synergistic effect can be summarized in the following two points:

[0072] (1) V-pit 4 enables localized emission of Micro-LED pixels: In the field of pixel-level collimation, the size of the superlens is limited by the pixel period, making it impossible to approximate Micro-LED as a point source. At this time, the spatial incoherence introduced by the extended surface light source greatly affects the control effect of the superlens. However, after introducing V-pit 4, on the one hand, the internal quantum efficiency of the light source 5 is improved, and on the other hand, photons are guided to recombine and emit at V-pit 4, forming a ring-shaped emission pattern within a small range. At this time, the actual emission area is reduced to 1%~25% of the original surface light source area. Compared with the area of ​​the superlens, it can be approximated as a point source, which greatly reduces the design difficulty of the first stage of the superlens and improves the collimation effect of the superlens.

[0073] (2) Matching the emission wavelength of V-pit 4 with the superlens: Due to the polycrystalline characteristics of V-pit 4, its emission wavelength is different from that of the c-plane. Therefore, a superlens that works in the corresponding wavelength band can be designed specifically for the emission wavelength of V-pit 4. At this time, only the light emitted from V-pit 4 is collected and collimated by the superlens, while the light of other wavelengths at the c-plane is scattered by the superlens, ultimately achieving an excellent collimation effect. The high emission ratio of V-pit 4 itself also ensures the overall light extraction efficiency after filtering out the light emitted from the c-plane. Therefore, the overall structure can achieve an excellent collimation effect under the premise of high light extraction efficiency, which has important application value in eliminating pixel crosstalk, improving display resolution and imaging quality, and integrating ultra-miniature imaging systems.

[0074] This device can be fabricated using methods such as superlens array transfer, nanoimprinting, or on-chip growth and etching. Figure 7 , Figure 8 The simulated structure and simulated emission angle spectrum of the V-pit 4-superlens co-modulated Micro-LED optical collimation are shown respectively. Figure 9This study demonstrates the collimation effect of the superlens without the introduction of V-pit 4 co-modulation, serving as a control group. The Micro-LED structure and size, the size and position of the V-pit 4, and the focal length and size of the superlens can all be adjusted and specifically optimized according to practical applications. Simulation results show that due to the incoherent surface light source characteristics of Micro-LEDs, the collimation performance using only microlenses or superlenses is poor. However, with the introduction of V-pit 4 co-modulation, the half-divergence angle is only 1.75°, achieving a near-0° collimated beam at the micrometer scale with the superlens size comparable to the pixel size. Peak power is increased by 120%, and total power by 21.8%. Considering applications such as AR, which require collecting collimated light at specific angles, the introduction of V-pit 4 co-modulation increases the zero-degree power (corresponding to the direct direction) by 614% and the total power within a 10° collection angle by 75.1%, achieving excellent pixel-level collimation and demonstrating significant application potential.

[0075] In summary, the Micro-LED pixel-level collimation structure based on the synergistic modulation of V-pits and superlenses provided by this invention has the following advantages:

[0076] 1. Innovative internal and external collaborative design of the light source, breaking through the bottleneck of incoherent light modulation.

[0077] This invention proposes for the first time a collaborative modulation mechanism between the V-pit 4 and the superlens light source 5, achieving optimization of the entire physical process from photon generation to light field propagation. It provides a new paradigm for the efficient control of incoherent surface light sources such as Micro-LEDs, and represents a fundamental innovation and breakthrough compared to existing superlens control of incoherent surface light sources.

[0078] Combining the advantages of in-source V-pit 4 modulation and external superlens modulation, this method utilizes the polycrystalline properties of V-pit 4 to form a source micro / nano structure with controllable position and wavelength, enhancing light extraction efficiency while improving the coherence of Micro-LEDs. It effectively reduces the design difficulty of superlenses and improves the collimation performance of subsequent superlenses. It also eliminates the need for complex structures such as resonant cavities or quantum well metasurfaces, significantly simplifying the process chain.

[0079] 2. Process compatibility and high integration

[0080] Micro-LEDs containing V-pits can be directly grown using PSS, ensuring compatibility with existing Micro-LED production lines. Meanwhile, superlenses can be directly integrated onto the surface of Micro-LED chips via epitaxial growth or nanoimprint lithography, achieving compatibility with existing Micro-LED production lines while avoiding the complex photolithography and bonding processes of traditional microlenses, significantly reducing manufacturing costs and yield risks.

[0081] Compared to traditional microlens solutions, the integration is greatly improved. The superlens is less than 1μm thick and can be directly attached to the surface of Micro-LED, which greatly reduces the size of the optical module and features high integration, miniaturization, and arraying.

[0082] 3. Improved light efficiency, uniformity, and collimation performance

[0083] By introducing a V-pit structure within the source, the internal quantum efficiency and light emission uniformity of Micro-LEDs are improved; combined with a superlens, a collimation angle of nearly 0° is achieved while maintaining extremely high light emission efficiency, significantly exceeding the performance limit of existing microlens or metasurface pixel-level collimation solutions.

[0084] 4. Multi-scenario adaptation and commercialization potential

[0085] It is compatible with all visible light bands. Through the V-pit 4 multi-wavelength emission characteristics and the broadband phase design of the super lens, it supports independent collimation of RGB sub-pixels, meets the requirements of full-color display, and solves the pain points of large color difference and limited band in existing solutions.

[0086] Extremely high collimation performance and micron-level size support high pixel density Micro-LED array applications, laying the technological foundation for cutting-edge fields such as AR / VR, automotive displays, and optical communications; combined with nanoimprint technology, it can realize the mass production of superlens arrays, accelerate the popularization of Micro-LED in the consumer electronics market, and has high commercialization potential.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Micro-LED pixel-level collimation structure based on V-groove and superlens synergistic modulation, characterized in that, include: Pixel-level collimating superlens (1), including: Superlens substrate; Multiple nanopillars are disposed on the superlens substrate; Micro-LED pixel structure (2) is attached to one side of the superlens substrate. The Micro-LED pixel structure (2) contains V pits (4) to guide carriers to recombine and emit light in the V pit (4) region. The V pits (4) extend in the opposite direction to the pixel-level collimating superlens (1). A patterned substrate (3) is attached to one side of the Micro-LED pixel structure (2) away from the superlens substrate. The patterned substrate (3) has protrusions, and the protrusions are disposed opposite to the V-pits (4). Multiple nanopillars form a nanopillar array, and multiple nanopillar arrays are disposed on a superlens substrate; Multiple Micro-LED pixel structures (2) are provided, each Micro-LED pixel structure (2) contains a V-pit (4), and each V-pit (4) is provided corresponding to a nanopillar array.

2. The Micro-LED pixel-level collimation structure based on V-groove and superlens synergistic modulation according to claim 1, characterized in that, The nanopillars are silicon nitride nanopillars or titanium oxide nanopillars.

3. The Micro-LED pixel-level collimation structure based on V-groove and superlens synergistic modulation according to claim 1, characterized in that, The Micro-LED pixel structure (2) includes a transparent conductive layer, a P-type gallium nitride layer, a multi-quantum well layer and an N-type gallium nitride layer stacked sequentially.

4. The Micro-LED pixel-level collimation structure based on V-groove and superlens synergistic modulation according to claim 1, characterized in that, The patterned substrate (3) includes a patterned sapphire substrate.

5. The Micro-LED pixel-level collimation structure based on V-groove and superlens synergistic modulation according to claim 1, characterized in that, The protrusions on the patterned substrate (3) are semi-circular protrusions or conical protrusions.

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