LED device

Abstract

According to the LED device provided by the invention, the light modulation layer is arranged on the surface of the optical lens or the surface / interior of the LED chip, so that the performance of the device is remarkably improved: if the light modulation layer is arranged on the surface of the optical lens, the microstructure of the light modulation layer can secondarily refract or diffract light rays emitted by the lens, edge divergent light is converged to the center, and light energy scattering is reduced; if the light modulation layer is located on the surface of the LED chip or in the LED chip, the isotropy of spontaneous radiation can be inhibited through the microstructure, stimulated radiation in the vertical direction is enhanced, and internal reflection loss is reduced. Therefore, light absorption and scattering are reduced, the light output efficiency and power are improved, the light beam quality is greatly improved, the half-peak full-width divergence angle is reduced, high light beam collimation is achieved, and the device is suitable for scenes such as directional illumination and optical communication. Meanwhile, the integration of the light modulation layer avoids the use of additional collimating elements, enhances the flexibility of optical design, and promotes the miniaturization and integration development of the device.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor optoelectronics, and in particular to an LED device. BACKGROUND

[0002] In recent years, light-emitting diodes (LEDs) prepared from third-generation semiconductor materials have the characteristics of energy saving, environmental protection, small size, long service life, fast response speed, controllable spectrum, high color rendering, and are widely used in lighting, display, communication, sensing, phototherapy, sterilization and other fields. However, the emitted light of the existing LED device is non-correlated dry light, which cannot meet the requirements of special scenes (such as beam collimation, or stray light, or fixed angle), and its light power is low, which seriously limits its application and development. SUMMARY

[0003] The present application relates to the field of semiconductor optoelectronics, and in particular to an LED device.

[0004] To solve the above technical problems, the present application provides an LED device, which comprises a packaging support, an optical lens and at least one LED chip, a placing groove is formed at the center of the packaging support, the LED chip is fixed to the bottom of the placing groove, and the optical lens is located above the packaging support and completely covers the placing groove. The LED device further comprises a light modulation layer, which is used to improve the collimation of the emitted light of the LED device. The light modulation layer is arranged on the side surface of the optical lens away from the packaging support, and / or the light modulation layer is located on the upper surface of the LED chip.

[0005] Preferably, the light modulation layer is of a symmetrical structure and comprises a plurality of spaced micro-columnar pieces, and the width of the plurality of micro-columnar pieces decreases linearly from the center of the light modulation layer to both ends.

[0006] Preferably, the width of the micro-columnar piece is 10-200 nm, the distance between the adjacent two micro-columnar pieces is 10-100 nm, and the included angle between the side wall and the bottom surface of the micro-columnar piece is 50°-90°.

[0007] Preferably, the height of the micro-columnar piece is h, the wavelength of the emitted light is λ, and the refractive index of the light modulation layer is n, wherein the relationship between h, λ and n is as follows: h=k x .

[0008] Preferably, a metal layer is arranged on the support plane of the packaging support, and the optical lens, the metal layer and the packaging support form a closed cavity. The side surface of the optical lens close to the LED chip is provided with a grating structure.

[0009] Preferably, when the light modulation layer is arranged on the side surface of the optical lens away from the package support, the refractive index of the light modulation layer is less than or equal to the refractive index of the optical lens; when the light modulation layer is arranged on the upper surface of the LED chip, the refractive index of the light modulation layer is less than the refractive index of the optical lens.

[0010] Preferably, when the light modulation layer is arranged on the upper surface of the LED chip, the LED chip comprises, from bottom to top, a conductive support layer, a bonding layer, a reflective layer, a P-type contact layer, a hole injection layer, an electron blocking layer, a quantum well active layer, and an electron injection layer arranged in sequence, and the light modulation layer is arranged above the electron injection layer and in contact with the electron injection layer.

[0011] Preferably, the electron injection layer comprises a plurality of spaced-apart protrusions and a plurality of grooves arranged between adjacent two protrusions, the upper surface of the protrusion is formed with an N-type contact layer, and the light modulation layer is arranged at the bottom of the groove and in contact with the sidewall of the adjacent protrusion.

[0012] Preferably, the LED device further comprises a high-transmittance layer arranged on the electron injection layer and completely covering the light modulation layer, and the refractive index of the high-transmittance layer is greater than the refractive index of the light modulation layer.

[0013] Preferably, the LED device further comprises a high-transmittance layer, and the material of the light modulation layer or the high-transmittance layer comprises at least one of silicon dioxide, silicon nitride, hafnium oxide, magnesium fluoride, titanium dioxide, and aluminum gallium nitride.

[0014] The LED device provided by the present application has the following advantages: compared with the prior art, the present application provides an LED device, which significantly improves the performance of the device by arranging a light modulation layer on the surface of the optical lens or on the surface / inside of the LED chip: the light emitted by the LED chip has the characteristics of strong divergence and easy loss due to total reflection, and the traditional LED device cannot fully utilize the light energy. If the light modulation layer is arranged on the surface of the optical lens, the microstructure of the light modulation layer can refract or diffract the light emitted by the lens, converge the edge divergent light to the center, and reduce the scattering of light energy; if the light modulation layer is arranged on the surface or inside of the LED chip, the microstructure can suppress the isotropy of spontaneous emission, enhance the stimulated emission in the vertical direction, and reduce the internal reflection loss. In this way, not only the light absorption and scattering are reduced, the light output efficiency and power are improved, but also the beam quality is greatly improved, the full width at half maximum divergence angle is reduced, the beam is highly collimated, and the device is suitable for directional lighting, optical communication and other scenes. At the same time, the integration of the light modulation layer avoids the use of additional collimating elements, enhances the flexibility of optical design, and promotes the development of small and integrated devices. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic diagram of the cross-sectional structure of the LED device provided by Embodiment 1 of the present application; Figure 2is a schematic diagram of the cross-sectional structure of the LED chip and the light modulation layer in the LED device provided in Embodiment 2 of the present application; Figure 3 is a schematic diagram of the cross-sectional structure of the LED chip and the light modulation layer at A in the LED device provided in Embodiment 3 of the present application; Figure 4 is a schematic diagram of the cross-sectional structure of the LED chip and the light modulation layer at A in the LED device provided in Embodiment 4 of the present application; In the description of the drawings: 100-LED device; 11-placing groove; 20-optical lens; 30-LED chip; 31-conductive support layer; 32-bonding layer; 33-reflective layer; 34-P-type contact layer; 35-hole injection layer; 36-electron blocking layer; 37-quantum well active layer; 38-electron injection layer; 381-boss; 382-groove; 39-N-type contact layer; 40-light modulation layer; 41-micro columnar part; 50-metal layer; 60-high-transmittance layer. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0017] At present, the control of the light beam angle of the existing LED device is mainly realized by different angle circular arc lenses, the angle of which is within a certain range, and a certain light power is lost. For the control of the light beam singularity, a filter is generally added at the module end, which will increase the complexity and integration difficulty of the system to a certain extent. Meanwhile, the light emitted in the existing LED device is non-correlated, which cannot meet the requirements of special scenes. The present application will utilize the interference, diffraction and optical path difference of light to regulate and control the propagation path of light inside and outside the LED device, and improve the light output power. For non-stray light, a grating structure is introduced to filter the light of a specific wavelength, while the light of other wavelengths is scattered and not transmitted. For light source collimation, a Fresnel zone is introduced, which utilizes the principle that the phase difference of the light emitted by adjacent half zones reaching a certain point is π, and the light vibration cancels out or strengthens each other, so that the light beams are superimposed at the focal point to produce a great light intensity, which plays a focusing role.

[0018] The technical solutions of the present application will be described in conjunction with specific embodiments.

[0019] Embodiment 1: Please refer to Figure 1 , Figure 1 is a schematic diagram of the cross-sectional structure of the LED device 100 provided in Embodiment 1 of the present application;Figure 1 It can be seen that the LED device 100 comprises a packaging support 10, an optical lens 20 and at least one LED chip 30, the packaging support 10 is provided with a placing groove 11 at the center, the LED chip 30 is fixed at the bottom of the placing groove 11, and the optical lens 20 is located above the packaging support 10 and completely covers the placing groove 11. The LED device 100 further comprises a light modulation layer 40, which is used to improve the collimation of the outgoing light of the LED device 100; the light modulation layer 40 is arranged on the side surface of the optical lens 20 away from the packaging support 10.

[0020] In the embodiment 1, the light modulation layer 40 can be prepared by ALD (atomic deposition process), PECVD (plasma enhanced chemical vapor deposition process), magnetron sputtering and the like, and the deposition temperature is lower than 300℃.

[0021] Specifically, the packaging support 1010 fixes the LED chip 30 through the placing groove 11 at the center, provides mechanical support and electrical connection, the internal conductive circuit transmits current, the high-thermal-conductivity material constructs a heat dissipation path, and can form a sealed cavity with the optical lens 20 and the metal layer to isolate the external environment, and part of the surface of the packaging support 1010 can be provided with a high-reflective film to improve the light extraction efficiency; the optical lens 20 converges the divergent light by using the refraction principle, compresses the beam divergence angle, cooperates with the light modulation layer 40 to optimize the beam quality, and can also realize specific light field distribution and spectrum shaping by design, and protects the LED chip 30 as a light-transmitting window, and realizes the optical matching between the LED chip 30 and the external environment.

[0022] Specifically, the LED device 100 provided in the embodiment 1 is provided with the light modulation layer 40 on the surface of the optical lens 20, which can significantly improve the device performance. In principle, the light emitted by the LED chip 30 has strong divergence, and direct emission will cause energy dispersion and loss, which is difficult to meet the needs of directional lighting, optical communication and the like. The addition of the light modulation layer 40 can converge the edge divergent light to the central direction through refraction, diffraction and other optical effects, greatly compress the beam divergence angle, and realize high collimation of light. This design reduces the scattering and reflection loss of light, improves the light output power and energy utilization rate, so that the illumination distance is farther and the light intensity is more concentrated under the same power; at the same time, without additional large collimating optical elements, the optical system structure is simplified, the cost is reduced, and the development of the device to miniaturization and integration is promoted, which has significant application advantages in the fields of automobile headlamps, laser radars and the like.

[0023] In the embodiment 1, the metal layer 50 is arranged on the support plane of the packaging support 10, the optical lens 20, the metal layer 50 and the packaging support 10 form a closed cavity, and the LED chip 30 is located in the closed cavity; wherein the metal layer 50, the packaging support 10 and the optical lens 20 form a fully closed structure, which can isolate external moisture, dust, oxygen and other environmental factors from eroding the LED chip 30 (such as avoiding chip electrode oxidation and fluorescent powder dampness failure), and improve the service life of the device in a high temperature and high humidity environment. The metal layer 50 is usually made of high thermal conductivity and corrosion-resistant material (such as copper, aluminum or alloy), and the sealing welding process (such as laser welding, brazing) with the packaging support 10 can achieve high airtightness, preventing short circuit or light-emitting efficiency decay of the LED chip 30 caused by water vapor penetration.

[0024] In the embodiment 1, in order to realize non-stray light, the grating structure can be designed on the surface of the optical lens 20 close to the LED chip 30. After the light emitted from the LED chip 30 passes through the grating structure, the excess wave band is filtered out, and the single wave band light enters the optical lens 20 and is focused by the light modulation layer 40, and finally a high collimation light source is obtained.

[0025] Specifically, when the mixed wave band light emitted by the LED chip 30 passes through the grating structure, the grating structure selectively filters out the excess wave band by using the diffraction principle, and only allows the specific single wave band light to pass through, avoiding the interference of stray light. These pure monochromatic light enters the optical lens 20, and then the light modulation layer 40 plays a role, and through refraction, diffraction and other optical effects, the light propagation path is regulated, so that the light is superimposed and converged, and finally a high collimation light beam is formed at the focal point, which significantly improves the purity and directionality of the light source, and can meet the requirements of the application scenarios of optical communication, precision detection and other light quality requirements.

[0026] In the embodiment 1, the light modulation layer 40 is a symmetrical structure and includes a plurality of spaced micro-columnar members 41 (divided into a series of annular regions according to a half-wavelength optical path difference), and the width of the plurality of micro-columnar members 41 linearly decreases from the center of the light modulation layer 40 to both ends (the width of the outermost micro-columnar member 41 can be nm level as the number increases).

[0027] Specifically, the embodiment 1 realizes light source collimation and focusing by introducing Fresnel zone structure (symmetrical annular micro-pillars 41 array) in the light modulation layer 40, using the interference principle of adjacent half-zone optical path difference π. Specifically, the light modulation layer 40 is divided into annular regions with an optical path difference of λ / 2, and the width of the micro-pillars 41 decreases linearly from the center to the two ends to the nanometer level, so that the vibration superposition of the light emitted by each wave band at the focal point due to the phase difference π forms a light intensity maximum. At the same time, through the design of wave band angle control (> 50°, optimally > 80°) and etching depth (proportional to wavelength, inversely proportional to 2(n-1)), the optical path difference matching and light emission angle are optimized, and finally the LED device 100 converts the divergent light into a highly collimated focused light beam, significantly improving the directionality and energy concentration of the light source.

[0028] In the embodiment 1, the width of the micro-pillars 41 is 10-200 nm, the distance between the adjacent two micro-pillars 41 is 10-100 nm, and the angle between the side wall and the bottom surface of the micro-pillar 41 is 50°-90°. Among them, the width of the micro-pillar 41 is set to 10-200 nm, and the distance between the adjacent two micro-pillars 41 is 10-100 nm. This size range can accurately match the ultraviolet to near-infrared wave band, meet the condition of Fresnel zone optical path difference λ / 2, and effectively improve the light energy concentration and diffraction efficiency by means of sub-wavelength structure excitation plasmon resonance or medium diffraction effect. The angle α between the side wall and the bottom surface of 50°-90° can flexibly regulate the optical path difference and phase gradient, adjust the refraction and reflection angle of the micro-pillar to the light, ensure the interference of the adjacent wave band light, and form a highly collimated light beam at the focal point. The multi-parameter collaborative optimization realizes the efficient collimation and focusing of the LED device 100. In order to achieve better focusing effect and high light output power, the optimal angle α is above 80°.

[0029] In the embodiment 1, the height (etching depth) of the micro-pillar 41 affects the light emission angle and light output power. The height of the micro-pillar 41 is h, the wavelength of the emitted light is λ, and the refractive index of the light modulation layer 40 is n. The relationship among h, λ and n is as follows: h=k× ; Wherein, by setting the constant k (usually taking 1, 2 and the like), the optical path difference between adjacent micro-pillars 41 is k×0.5λ: when k=1, the optical path difference is half wavelength, realizing the interference and focusing of Fresnel zone; the greater the refractive index n, the greater the value of n-1, and the height h is correspondingly reduced, while the longer the wavelength λ, the greater the h. This formula can guide the accurate design of micro-pillar height according to the actual wavelength and material refractive index, ensure the phase regulation accuracy of the light modulation layer 40 to the light, and further realize the output of highly collimated light beam.

[0030] In the embodiment 1, when the light modulation layer 40 is arranged on the side surface of the optical lens 20 away from the packaging support 10, the refractive index of the light modulation layer 40 is less than or equal to the refractive index of the optical lens 20, so that the better exit angle is achieved, and the refractive index difference between the optical lens 20 and the air is reduced, and the total reflection loss is reduced.

[0031] Specifically, when the light modulation layer 40 is arranged on the side surface of the optical lens 20 away from the packaging support 10, the refractive index of the light modulation layer 40 is designed to be less than or equal to the refractive index of the optical lens 20, which optimizes the light extraction efficiency through the gradient refractive index matching mechanism. On the one hand, the refractive index difference between the light modulation layer 40 and the optical lens 20 is reduced, so that the refraction angle changes more gently when the light is transmitted between the layers, and the light scattering caused by the refractive index mutation is avoided. On the other hand, the light modulation layer 40 acts as a transition layer between the optical lens 20 and the air, which can reduce the direct refractive index difference between the optical lens 20 (high refractive index, such as n=1.5~2.0) and the air (n=1). When the light enters the light modulation layer 40 from the optical lens 20 and then exits to the air, the critical angle of total reflection increases (for example, the critical angle is about 33° when the lens n=1.8, and the critical angle is increased to 38° after the light modulation layer 40 with n=1.6 is added), and more light exits at an angle smaller than the critical angle, reducing the light energy loss caused by total reflection. At the same time, the exit angle is adjusted through the microstructure (micro columnar parts 41) of the light modulation layer 40, and the light output efficiency can be increased by 10%~20% under the premise of ensuring high collimation.

[0032] Further, on the basis of the LED device 100 provided in the embodiment 1, a light modulation layer 40 can be additionally designed on the upper surface of the LED chip 30, the refractive index of the light modulation layer 40 is lower than the refractive index of the optical lens 20; the light modulation layer 40 acts as a transition medium between the LED chip 30 (high refractive index, n≈3.5) and the optical lens 20 (medium-high refractive index, n≥light modulation layer 40), and a "light refraction buffer zone" is formed due to the refractive index difference: when the light emitted by the LED chip 30 enters the light modulation layer 40, the increased refraction angle makes more light exit in a nearly vertical direction, reducing the total reflection loss at the LED chip 30-air interface; and the "low-high" refractive index interface between the light modulation layer 40 and the optical lens 20 can also make the refraction angle of the light entering the optical lens 20 decrease, which forms a cascade optimization of "chip-end pre-collimation-lens-end precise focusing" in combination with the focusing of the optical lens 20 and the secondary collimation of the light modulation layer 40 on the upper surface. Compared with the single light modulation layer 40 structure, the beam full width at half maximum (FWHM) is further compressed by 15%~30%, and the light extraction efficiency is increased by more than 20%, while the light scattering caused by the refractive index mutation is avoided, and the high-efficiency output of the high-collimation light beam is realized.

[0033] Embodiment 2: Please refer to Figure 2 , Figure 2is a schematic diagram of a cross-sectional structure of the LED chip 30 and the light modulation layer 40 in the LED device 100 provided in Embodiment 2 of the present application; the LED chip 30 is Figure 2 It can be seen that the light modulation layer 40 in the LED device 100 is located on the upper surface of the LED chip 30.

[0034] In Embodiment 2, when the light modulation layer 40 is located on the upper surface of the LED chip 30, the LED chip 30 is preferably a vertical deep ultraviolet light emitting diode chip, and the LED chip 30 comprises, from bottom to top, a conductive support layer 31, a bonding layer 32, a reflective layer 33, a P-type contact layer 34, a hole injection layer 35, an electron blocking layer 36, a quantum well active layer 37, and an electron injection layer 38 which are arranged in sequence. The electron injection layer 38 comprises a plurality of spaced-apart protrusions 381 and a plurality of grooves 382 located between adjacent two protrusions 381, the upper surface of the protrusion 381 is formed with an N-type contact layer 39, and the light modulation layer 40 is located at the bottom of the groove 382 and in contact with the sidewall of the protrusion 381 adjacent to the groove 382. Figure 2 The part A in the middle).

[0035] In Embodiment 2, the material of the conductive support layer 31 is any one of Si, SiC and Cu; the conductive support layer 31 can play a supporting role, and can also be reused as a P-type electrode in the present application.

[0036] In Embodiment 2, the material of the bonding layer 32 is any one of Au-Au, Au-Sn and Sn-Sn; the bonding layer 32 is used to bond the reflective layer 33 and the conductive support layer 31.

[0037] In Embodiment 2, the material of the reflective layer 33 is at least one of Al, Rh and Ag; the reflective layer 33 is used to reflect ultraviolet light emitted by the quantum well active layer 37 to the conductive support layer 31, so that the ultraviolet light is emitted in the first direction D1.

[0038] In Embodiment 2, the material of the P-type contact layer 34 includes but is not limited to a single layer or a stack of NiAu, ITO, Rh, Al, etc.; in an embodiment, the P-type contact layer 34 is Rh, and the thickness is 10-70 nm.

[0039] In Embodiment 2, the material of the hole injection layer 35 is Mg-doped AlGaN material, and the doping concentration is between 10 18 cm -3 and 10 20 cm -3 ; the thickness of the hole injection layer 35 is preferably 1-10 μm.

[0040] In embodiment 2, the electron blocking layer 36 is a single layer of AlGaN structure, the electron blocking layer 36 is Mg-doped semiconductor material, and the electron blocking layer 36 uses dimethyl magnesium as a dopant; wherein the aluminum component content of the electron blocking layer 36 is greater than or equal to 50% and less than 100%, and the thickness of the electron blocking layer 36 ranges from 0.1 nm to 200 nm.

[0041] In embodiment 2, the quantum well active layer 37 includes at least one potential well layer and at least two potential barrier layers arranged alternately, and each potential well layer is inserted between two adjacent potential barrier layers; wherein the potential well layer and the potential barrier layer each include AlGaN material, and the total aluminum component content of each potential well layer is lower than the total aluminum component content of each potential barrier layer, so as to ensure that the carriers in the quantum well active layer 37 are confined in the potential well layer.

[0042] Further, the material of the potential well layer is Al x1 Ga y1 N, the thickness of the potential well layer is 0.1 nm-5 nm, wherein 30% < x1 < 80%, and x1 + y1 = 1; the material of the potential barrier layer is Al x2 Ga y2 N, the thickness of the potential barrier layer is 1 nm-30 nm, wherein 40% < x2 < 90%, and x2 + y2 = 1.

[0043] Further, the number of periods of the quantum well active layer 37 is greater than or equal to 1 and less than or equal to 20, and the number of periods is a positive integer.

[0044] In embodiment 2, the electron injection layer 38 is made of Si-doped AlGaN material, and the doping concentration is between 10 18 cm -3 -10 20 cm -3 ; the thickness of the electron injection layer 38 is preferably 1 μm-10 μm.

[0045] Further, the electron injection layer 38 includes a plurality of protrusions 381 and a plurality of grooves 382 located between adjacent two protrusions 381, and the upper surface of the protrusion 381 forms the N-type contact layer 39; wherein the number of the grooves 382 is greater than or equal to 1. The upper surface of the protrusion 381 is a roughened surface, and the roughened surface is used to extract light emitted by the quantum well active layer 37; wherein the roughened surface has a plurality of periodically arranged or irregularly arranged microstructures, and the microstructures are recessed or protruding.

[0046] In embodiment 2, the material of the N-type contact layer 39 includes but is not limited to single layer or stacked layers of Cr, Al, Ti, Au, Ni, Pt, Rh, Ag, etc., and the thickness is 100-200 nm.

[0047] Preferably, the height of the groove 382 is less than or equal to the thickness of the electron injection layer 38, and the width of the bottom surface of the groove 382 ranges from 50 nm to the size of the epitaxial wafer of the vertical deep ultraviolet light emitting diode 100.

[0048] Preferably, the cross-sectional shape of the convex 381 includes any one of a right trapezoid, an inverted trapezoid, a circular arc, and a cone, and the angle between the side surface of the convex 381 and the bottom surface of the convex 381 ranges from 5° to 89°.

[0049] The area of the groove 382 is positively correlated with the luminous intensity of the LED device 100 and is negatively correlated with the driving voltage of the LED device 100.

[0050] Further, considering the photoelectric conversion efficiency of the LED device 100, the cross-sectional area of the groove 382 is less than or equal to 0.6 times the cross-sectional area of the convex 381.

[0051] In the embodiment 2, the height and the angle of the groove 382 can be controlled by a mask process including but not limited to photoresist, silicon dioxide, etc., and an inductively coupled plasma (ICP) etching process. The height can be adjusted by the ICP gas atmosphere, power, and time. The angle can be adjusted by adjusting the angle of the mask material, the ICP gas atmosphere, and the power. The cross-sectional area can be adjusted by designing a photoetching mask plate.

[0052] Further, by designing multiple grooves 382 inside the electron injection layer 38, and each groove 382 at least penetrates part of the electron injection layer 38, it is beneficial for the ultraviolet light emitted by the quantum well active layer 37 to the electron injection layer 38 to be diffusely reflected along the side surface of the groove 382, thereby improving the light extraction efficiency of the LED device 100. At the same time, this design can also reduce the total reflection loss of photons and increase the light extraction efficiency.

[0053] In the embodiment 2, the light modulation layer 40 is located at the bottom of the groove 382 and in contact with the sidewall of the protrusion 381 adjacent to the groove 382; at this time, the refractive index of the light modulation layer 40 is lower than the refractive index of the optical lens 20. This design optimizes the light transmission path through the refractive index gradient matching: when the light emitted by the LED chip 30 (from the high refractive index chip n≈3.5 into the light modulation layer 40) enters the light modulation layer 40, the refractive angle of the light is increased due to the low refractive index of the light modulation layer 40 (such as n=1.8~2.0), and more light is emitted in a nearly vertical direction, reducing the total reflection loss of the chip-air interface; the low refractive index light modulation layer 40 and the high refractive index optical lens 20 form a "low-high" refractive index interface, and the refractive angle of the light entering the optical lens 20 is reduced, which can further compress the beam divergence angle with the focusing effect of the lens, while avoiding light scattering caused by the refractive index jump. This structure builds a gradual optical interface through two refractive index regulation (LED chip 30→light modulation layer 40→optical lens 20→air), which can improve the light extraction efficiency by 15%~25% and ensure the output quality of the high collimation light beam.

[0054] Specifically, the material of the light modulation layer 40 can be the same material as the electron injection layer 38, or a material with low refractive index and high transmittance in the ultraviolet band, including but not limited to silicon dioxide, silicon nitride, hafnium oxide, magnesium fluoride, titanium dioxide, or multiple layers, etc. It can be realized by ALD, PECVD, magnetron sputtering, etc. The deposition temperature is lower than 300℃.

[0055] Embodiment 3: Please refer to Figure 3 , Figure 3 is the cross-sectional structure schematic diagram of the LED chip 30 and the light modulation layer 40 at A in the LED device 100 provided in the embodiment 3 of the present application. The structure of the LED device 100 provided in the embodiment 3 is substantially the same as the structure of the LED device 100 provided in the embodiment 2, and the difference is only that the structure of the part at A in Figure 2 is different: In the embodiment 3: the electron injection layer 38 is not provided with the protrusion 381, the light modulation layer 40 and the N-type contact layer 39 are provided on the electron injection layer 38 in the same layer, and the light modulation layer 40 is located in the "dam" composed of the N-type contact layer 39 and the electron injection layer 38.

[0056] Specifically, the "dam" is composed of the N-type contact layer 39 and the electron injection layer 38, which limits the electron injection area by the electric field, improves the current density uniformity and injection efficiency, and at the same time, prevents short circuit as a physical barrier and enhances the structural stability; the light modulation layer 40 is highly overlapped with the electron injection area, which can synergistically control the light field and the carrier by means of plasmonic resonance or photonic crystal effect, and improve the radiation recombination and light extraction efficiency; the integration of the same layer avoids the interface problem of heterojunction multilayer deposition, reduces the process steps and cost. Compared with the boss 381 structure, this design performs better in terms of carrier control, reliability, etc., and is suitable for Micro-LED display, ultraviolet sterilization and other scenes with strict performance requirements.

[0057] In embodiment 3, the light modulation layer 40 is a material with low refractive index and high transmittance in the ultraviolet band, including but not limited to silicon dioxide, silicon nitride, hafnium oxide, magnesium fluoride, titanium dioxide or multiple layers, etc. It can be realized by ALD, PECVD, magnetron sputtering and other technologies, and the deposition temperature is lower than 300℃.

[0058] Embodiment 4: Please refer to Figure 4 , Figure 4 is a schematic diagram of the cross-sectional structure of the LED chip 30 and the light modulation layer 40 at A in the LED device 100 provided by embodiment 4 of the present application; the structure of the LED device 100 provided by embodiment 4 is substantially the same as that of the LED device 100 provided by embodiment 3, and the only difference is that Figure 3 the partial structure at A in In embodiment 4, the LED device 100 further comprises a high transmittance layer, which is arranged on the electron injection layer 38 and completely covers each micro-column 41 in the light modulation layer 40, and the refractive index of the high transmittance layer is greater than that of the light modulation layer 40.

[0059] In embodiment 4, by arranging a high transmittance layer on the electron injection layer 38 which completely covers the light modulation layer 40, and its refractive index is greater than that of the light modulation layer 40, the light transmission efficiency can be optimized by means of refractive index gradient matching mechanism. The high transmittance layer acts as a transition medium between the light modulation layer 40 and the upper structure, and forms a "light funnel" effect due to the difference in refractive index, so that the scattered light emitted by the micro-column 41 is refracted to the normal direction at the interface between the layers, reducing the reflection loss of light at the interface; at the same time, the high refractive index material (such as TiO2, n≈2.5) has stronger binding ability to light, which can further converge the collimated light regulated by the light modulation layer 40, compress the beam divergence angle, and cooperate with the subwavelength structure of the micro-column 41 to realize high-efficiency coupling of light energy from the low-refractive-index modulation layer to the high-refractive-index transmittance layer. Compared with the structure without the high transmittance layer, the light output efficiency is improved by 15%~25%, and the stray light is effectively suppressed to ensure the purity of the high collimated light beam.

[0060] In embodiment 4, when the material of the light modulation layer 40 is the same as the material of the electron injection layer 38, the material of the high-transmittance layer is a material with low refractive index and high transmittance in the ultraviolet band, including but not limited to silicon dioxide, silicon nitride, hafnium oxide, magnesium fluoride, titanium dioxide, or multiple layers, etc.; when the material of the light modulation layer 40 is a high-transmittance material, then the high-transmittance layer 60 is a high-transmittance material with a refractive index between the light modulation layer 40 and air. The high-transmittance layer 60 can be realized by ALD, PECVD, magnetron sputtering, etc., with a deposition temperature lower than 300°C.

[0061] In summary, compared with the prior art, the LED device 100 provided by the application has the following advantages: Firstly, the LED device 100 realizes the comprehensive improvement of beam performance, optical power, and device integration through the synergistic effect of multiple technical features. From the perspective of beam performance, the grating structure is arranged on the side of the optical lens 20 close to the LED chip 30, and the grating diffraction principle is used to filter the redundant waveband, allowing only single waveband light to enter the lens, realizing the single nature of the emitted light; the light modulation layer 40 introduces the Fresnel band structure, and the micro-columnar parts 41 divide the annular region according to the optical path difference λ / 2, and when the adjacent half-waveband light reaches the focal point, the phase difference is π, and the light vibration is superimposed to form a maximum light intensity, playing a focusing role. At the same time, by accurately designing the width (10-200 nm), spacing (10-100 nm), and side wall angle (50°-90°) of the micro-columnar parts 41, the angles of light refraction and reflection are controlled, realizing high collimation. If the grating is combined with the light modulation layer 40, the superposition of single nature and collimation can also be realized, meeting the performance requirements of special angles.

[0062] Secondly, in terms of optical power, the metal layer 50 on the support plane of the packaging support 10 forms a closed cavity with the optical lens 20 and the packaging support 10, and the metal layer 50 has high reflectivity (>90%) to reflect the light from the side and bottom of the LED chip 30 to the light-emitting direction, reducing light absorption loss and improving light extraction efficiency by 15%-20%; at the same time, the light modulation layer 40 with a lower refractive index than the optical lens 20 is arranged on the upper surface of the LED chip 30, and the refractive index gradient matching is used to reduce the loss of total reflection at the LED chip 30-air interface, and the cascade optimization of the optical lens 20 and the other light modulation layer 40 makes the optical power significantly improved.

[0063] Finally, in terms of device integration and preparation, the high-transmittance layer 60 covers the light modulation layer 40 and has a higher refractive index, forming a "light funnel" effect to converge light, and this layer is deposited with other structures in the same layer, avoiding complex multi-layer processes, realizing device integration and miniaturization, and the preparation process is simpler and more efficient.

[0064] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own emphasis. If the description is not exhaustive in an individual embodiment, the description in other embodiments can be referred to.

[0065] The above embodiments only express the implementation of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the inventive concept, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. An LED device, characterized by, The LED device comprises a packaging support, an optical lens and at least one LED chip, the packaging support is provided with a placing groove in the center, the LED chip is fixed on the bottom of the placing groove, and the optical lens is located above the packaging support and covers the placing groove completely. The LED device further comprises a light modulation layer, the light modulation layer is used to improve the collimation of the light emitted by the LED device, and the light modulation layer is arranged on the side surface of the optical lens away from the packaging support or on the upper surface of the LED chip.

2. The LED device of claim 1, wherein, The light modulation layer has a symmetrical structure and comprises a plurality of spaced micro columns, and the width of the micro columns decreases linearly from the center to the two ends of the light modulation layer.

3. The LED device of claim 2, wherein, The width of the micro columns is 10-200 nm, the distance between two adjacent micro columns is 10-100 nm, and the included angle between the side wall and the bottom surface of the micro column is 50-90°.

4. The LED device of claim 2, wherein, The height of the micro column is h, the wavelength of the emergent light is λ, and the refractive index of the light modulation layer is n, wherein the relationship between h, λ, and n is as follows: h=k× .

5. The LED device of claim 1, wherein, The support plane of the packaging support is provided with a metal layer, the optical lens, the metal layer and the packaging support form a closed cavity, and the side surface of the optical lens close to the LED chip is provided with a grating structure.

6. The LED device according to claim 1, wherein When the light modulation layer is arranged on the side surface of the optical lens away from the packaging support, the refractive index of the light modulation layer is less than or equal to the refractive index of the optical lens, and when the light modulation layer is arranged on the upper surface of the LED chip, the refractive index of the light modulation layer is less than the refractive index of the optical lens.

7. The LED device of claim 1, wherein, When the light modulation layer is arranged on the upper surface of the LED chip, the LED chip comprises, from bottom to top, a conductive support layer, a bonding layer, a reflection layer, a P-type contact layer, a hole injection layer, an electron blocking layer, a quantum well active layer and an electron injection layer which are arranged in sequence, and the light modulation layer is arranged above the electron injection layer and in contact with the electron injection layer.

8. The LED device of claim 7, wherein, The electron injection layer comprises a plurality of spaced convex platforms and a plurality of grooves between two adjacent convex platforms, the upper surface of the convex platform is provided with an N-type contact layer, and the light modulation layer is arranged on the bottom of the groove and in contact with the side wall of the adjacent convex platform.

9. The LED device of claim 7, wherein, The LED device further comprises a high-transmittance layer, the high-transmittance layer is arranged on the electron injection layer and covers the light modulation layer completely, and the refractive index of the high-transmittance layer is greater than that of the light modulation layer.

10. The LED device of claim 9, wherein, The material of the light modulation layer or the high-transmittance layer comprises at least one of silicon dioxide, silicon nitride, hafnium oxide, magnesium fluoride, titanium dioxide and aluminum gallium nitride.

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