Micro light emitting structure and micro light emitting device

Abstract

The application provides a micro light emitting structure and a micro light emitting device. The micro light emitting structure comprises a transparent substrate, and a semiconductor layer is arranged on the surface of the transparent substrate. The semiconductor layer extends outward from the surface of the transparent substrate in a partial region, thereby forming a step structure for light emission, and a channel is formed between adjacent step structures. The region of the semiconductor layer in the channel is covered with a refractive layer. The refractive index of the refractive layer is smaller than the refractive index of the semiconductor layer, and the light absorption rate of the refractive layer is greater than the light absorption rate of the semiconductor layer. In the micro light emitting structure, light crosstalk is less likely to occur between regions, and when the micro light emitting structure is used in a micro light emitting device, the display effect and contrast of the micro light emitting device can be improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor light-emitting technology, and more specifically, to a micro light-emitting structure and a micro light-emitting device. Background Technology

[0002] With the development of technology, LED (Light Emitting Diode) chips are becoming increasingly miniaturized and integrated, leading to the emergence of Micro-LED (Micro Light Emitting Diode) chips, which have attracted widespread attention. Micro-LED chips possess disruptive advantages such as high brightness, high resolution, low power consumption, long lifespan, and lightweight design, making them extremely valuable for research and application.

[0003] In the current structure used in 0.13-inch Micro-LED chip products, light from the light-emitting area can easily leak through the non-light-emitting channels between the light-emitting areas, resulting in poor contrast between the ideal light-emitting area and the adjacent non-light-emitting area. This leads to a low MTF (Modulation Transfer Function) value, causing the display to appear blurry and the contrast to deteriorate. Utility Model Content

[0004] This application provides a micro light-emitting structure and a micro light-emitting device. In the micro light-emitting structure of this application, optical crosstalk is not easily caused between different regions. When used in a micro light-emitting device, it can improve the display effect and contrast of the micro light-emitting device.

[0005] This application provides a micro light-emitting structure, which includes a transparent substrate, a semiconductor layer disposed on the surface of the transparent substrate, a portion of the surface of the semiconductor layer away from the transparent substrate extending outward to form a plurality of stepped structures for light emission, and a channel being formed between adjacent stepped structures; a refractive layer is covered in the region of the semiconductor layer located in the channel, the refractive index of the refractive layer being less than the refractive index of the semiconductor layer, and the light absorption of the refractive layer being greater than the light absorption of the semiconductor layer.

[0006] The semiconductor layer is an N-type GaN layer, and the refractive layer is a Ti layer.

[0007] The thickness of the refractive layer is 3nm to 100nm.

[0008] The refractive index of the refractive layer is 0.1 to 0.5 higher than that of the semiconductor layer.

[0009] The light absorption rate of the refractive layer ranges from 20% to 90%.

[0010] The stepped structure includes a quantum well layer for luminescence, with the distance from the quantum well layer to the transparent substrate being R1 and the distance from the refractive layer to the transparent substrate being R2, where R1 < R2.

[0011] The cross-section of the stepped structure is trapezoidal, and the plane containing the upper base of the trapezoid is far from the transparent substrate.

[0012] The transparent substrate is made of U-shaped GaN and has a thickness of 0.5μm to 5μm.

[0013] The height of the step structure ranges from 0.5μm to 2.5μm.

[0014] This application also provides a micro light-emitting device, which includes the micro light-emitting structure described above.

[0015] The beneficial effects of this application are as follows:

[0016] This application provides a micro-light-emitting structure and a micro-light-emitting device. In the micro-light-emitting structure of this application, the surface of the channel located between the stepped structures is covered with a refractive layer, and the light absorption rate of the refractive layer is greater than that of the semiconductor layer. Therefore, when the light emitted from the stepped structure passes through the refractive layer and enters the surface of the semiconductor layer, part of the light is absorbed by the refractive layer, which reduces light crosstalk in the non-light-emitting area and improves the display contrast and MTF value. In addition, since the refractive index of the refractive layer is less than that of the semiconductor layer, when light passes through the refractive layer and enters the semiconductor layer and the transparent substrate, the incident angle of the light becomes smaller, and the final exit angle of the light also becomes smaller. This reduces the light diffusion range, which can improve the contrast and narrow the field of view. Moreover, since the refractive index of the refractive layer is smaller than that of the semiconductor layer, total internal reflection does not occur at the interface between the semiconductor layer and the refractive layer, which also helps to improve the contrast. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a micro-luminescent structure in the existing technology;

[0019] Figure 2 This is a micro-light-emitting structure in the embodiments of this application.

[0020] Explanation of reference numerals in the attached figures: 001 - micro-light-emitting structure; 010 - micro-light-emitting structure; 100 - transparent substrate; 200 - semiconductor layer; 210 - stepped structure; 211 - quantum well layer; 220 - channel; 230 - refractive layer. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0022] In the description of this application, 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," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not 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 application. 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, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0025] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0026] In existing technologies, light from the emitting area of ​​the micro-light-emitting structure 010 easily escapes from the non-emitting area, resulting in a blurry display and poor contrast. The structure of the micro-light-emitting structure 010 is as follows: Figure 1 As shown.

[0027] Based on this, this application provides a micro light-emitting structure 001 and a micro light-emitting device. The micro light-emitting structure 001 in this application is less prone to optical crosstalk between different regions, so the micro light-emitting structure 001 and the micro light-emitting device in this application have good display effect and contrast.

[0028] Before describing the embodiments of this application, the definitions and test methods of refractive index and absorbance are explained in detail:

[0029] Refractive index is the ratio of the speed of light in a vacuum to the speed of light in a medium. The test method is to fabricate a thin film material of the target thickness on a silicon wafer with a thickness of more than 0.5 mm, and use an ellipsometry to measure the thickness and refractive index of the target film layer. Film formation methods such as CVD (Chemical Vapor Deposition), PVD (Physical Vapor Deposition), evaporation, coating, and ALD (Atomic Layer Deposition) can be used.

[0030] Absorbance refers to the reduction in light intensity due to absorption when light passes through a solution or solid. This application uses visible light as an example to compare the absorbance of various structures. The testing method involves fabricating a thin film material of the target thickness (using film formation methods such as CVD / PVD / evaporation / coating / ALD, etc.) on a double-sided polished transparent glass slide with a thickness of 0.2–1 mm, using the same glass slide as a control group. 1. The film layer to be tested is placed vertically in front of the spectrophotometer before incident light, and the reflectance and transmittance are measured across the entire wavelength range. 100% - reflectance - transmittance gives the full-wavelength absorptivity of the material at that thickness. 2. The control group glass slide is placed vertically in front of the spectrophotometer before incident light, and the reflectance and transmittance are measured across the entire wavelength range. 100% - reflectance - transmittance gives the full-wavelength absorptivity of the stripped slide. 3. ab at the target wavelength range is the absorptivity of the material of that thickness for a certain wavelength range.

[0031] like Figure 2 As shown, the micro light-emitting structure 001 of this application includes a transparent substrate 100, and a semiconductor layer 200 is disposed on the surface of the transparent substrate 100. A portion of the surface of the semiconductor layer 200 away from the transparent substrate 100 extends outward to form a plurality of step structures 210 for light emission, and a channel 220 is formed between adjacent step structures 210. A refractive layer 230 is covered in the region of the semiconductor layer 200 located in the channel 220. The refractive index of the refractive layer 230 is less than the refractive index of the semiconductor layer 200, and the light absorption rate of the refractive layer 230 is greater than the light absorption rate of the semiconductor layer 200.

[0032] In this application, the step structure 210 in the semiconductor layer 200 emits light, while the channel 220 does not. The light emitted by the step structure 210 passes through the transparent substrate 100 and enters the human eye. The step structure 210 and the channel 220 work together to ensure that the micro-light-emitting structure 001 can display images. The light emitted by the step structure 210 in the semiconductor layer 200 inevitably enters the channel 220. Since the surface of the channel 220 is covered with a refractive layer 230, and the light absorption rate of the refractive layer 230 is greater than that of the semiconductor layer 200, when the light emitted by the step structure 210 passes through the refractive layer 230 and enters the surface of the semiconductor layer 200, some of the light is absorbed by the refractive layer 230. This reduces light crosstalk in the non-light-emitting area and improves the display contrast and MTF value. Furthermore, since the refractive index of the refractive layer 230 is less than that of the semiconductor layer 200, when light passes through the refractive layer 230 into the semiconductor layer 200 and the transparent substrate 100, the incident angle of the light becomes smaller, and the final outgoing light angle also becomes smaller. This reduces the light diffusion range, which can improve contrast and narrow the field of view. Moreover, since the refractive index of the refractive layer 230 is smaller than that of the semiconductor layer 200, total internal reflection will not occur at the interface between the semiconductor layer 200 and the refractive layer 230, which can also improve contrast. In some embodiments of this application, in order to enable the micro light-emitting structure 001 to have a good display effect and to improve the heat dissipation efficiency of the light-emitting diode, the transparent substrate 100 is usually made of U-shaped GaN with a thickness of 0.5μm to 5μm; where U-shaped stands for Undoped, and U-shaped GaN is undoped GaN. U-shaped GaN has high light transmittance and good heat dissipation.

[0033] This application does not have any special requirements for the material of the refractive layer 230, as long as it can meet the purpose of this application. In some embodiments of this application, considering the heat dissipation and luminous efficiency of the micro light-emitting structure 001, the semiconductor layer 200 is usually made of N-type GaN, so that the micro light-emitting structure 001 has good heat dissipation performance and high luminous efficiency. In this case, the material of the refractive layer 230 can be Ti.

[0034] A higher contrast ratio is not always better. While increased contrast can improve display quality in low-light environments, excessively high contrast is not eye-friendly and can cause eye strain. Therefore, in some embodiments of this application, to ensure that the contrast ratio of the micro-light-emitting structure 001 is within a suitable range and does not easily cause eye strain, the refractive index of the refractive layer 230 is typically set to be 0.1 to 0.5 higher than that of the semiconductor layer 200. Similarly, in some embodiments of this application, the light absorption rate is set to 20% to 90%, which also ensures that the contrast ratio of the micro-light-emitting structure 001 is within a suitable range while minimizing eye strain.

[0035] In order to ensure that the refractive layer 230 has a suitable light absorption and refractive index to meet the actual use requirements, in some embodiments of this application, the thickness of the refractive layer 230 can be 3nm to 100nm; specifically, the thickness of the refractive layer 230 can be 3nm, 10nm, 20nm, 50nm, 80nm, 90nm, 100nm, etc., or within the range of any two of the above values.

[0036] To ensure the stepped structure 210 exhibits good light-emitting performance, in some embodiments of this application, the stepped structure 210 includes a quantum well layer 211, which functions as a light-emitting element. During the light-emitting process, electrons and holes are injected into the quantum well layer 211. These injected electrons and holes are in an excited state, recombine with each other, and release energy, which manifests as light and heat. Therefore, the quantum well layer 211 can emit light. The process of injecting electrons and holes can be achieved by applying an external voltage to the light-emitting diode. In the embodiments of this application, the distance from the quantum well to the transparent substrate 100 is R1, and the distance from the refractive layer 230 to the transparent substrate 100 is R2, where R1 < R2, meaning the distance from the quantum well layer 211 to the transparent substrate 100 is greater than the distance from the refractive layer 230 to the transparent substrate 100. At this time, most of the light transmitted from the quantum well layer 211 through the stepped structure 210 and reaching the channel 220 will pass through the refractive layer 230, so the refractive layer 230 can better improve the contrast and display effect of the light-emitting diode.

[0037] This application does not impose any particular limitation on the material of the quantum well layer 211, as long as it meets the purpose of this application. For example, in some embodiments of this application, it may be an indium gallium nitride quantum well layer 211, or it may be an indium gallium nitride / gallium nitride multi-quantum well layer 211.

[0038] Furthermore, in some embodiments of this application, the cross-sectional shape of the stepped structure 210 is trapezoidal, and the plane containing the upper base of the trapezoid is far from the transparent substrate 100. Setting the cross-section of the stepped structure 210 to be trapezoidal is beneficial for increasing the light-emitting area. Moreover, since the plane containing the upper base of the trapezoid in the stepped structure 210 is far from the transparent substrate 100, it can be ensured that most of the light transmitted from the side of the stepped structure 210 and reaching the channel 220 will pass through the refractive layer 230.

[0039] This application does not have any particular requirements for the height of the step structure 210, as long as it meets the purpose of this application. As an example, in some embodiments of this application, the height of the step structure 210 can be 0.5μm to 2.5μm.

[0040] This application also provides a miniature light-emitting device, which includes the miniature light-emitting structure 001 described in this application. Therefore, the miniature light-emitting device of this application has excellent display effect and contrast. The miniature light-emitting device of this application can be used in multiple fields and devices.

[0041] When the micro-light-emitting structure 001 of this application is in operation, some of the light emitted from the quantum well layer 211 passes through the side of the stepped structure 210 and enters the channel 220. At this time, the light passes through the refractive layer 230 and is partially absorbed. Therefore, when the light passing through the side of the stepped structure 210 reaches the human eye, its intensity is much less than the initial intensity of the light passing through the side of the stepped structure 210, thus achieving the effect of improving contrast. In addition, since the refractive index of the refractive layer 230 is less than that of the semiconductor layer 200, the light entering the refractive layer 230 is closer to the normal, resulting in a smaller exit angle of the light passing through the refractive layer 230, which can play a role in narrowing the field of view. In addition, when the micro light-emitting structure 001 of this application is working, part of the light emitted by the quantum well layer 211 will be reflected by the transparent substrate 100 into the refractive layer 230 (i.e. the light propagates laterally). At this time, the refractive layer 230 will also reduce the light intensity and the emission angle, thereby improving the contrast of the micro light-emitting structure 001 and narrowing the field of view.

[0042] When the existing micro-light-emitting structure 010 is in operation, some of the light emitted from the quantum well layer 211 passes through the side of the stepped structure 210 and enters the channel 220 before being received by the human eye. Some light also passes through multiple reflections from the transparent substrate 100 before being received by the human eye. However, due to the lack of light absorption by the refractive layer 230, the intensity of this excess light is not significantly reduced, which can easily lead to a deterioration in the contrast and display effect of the micro-light-emitting structure 001, and it also fails to narrow the field of view.

[0043] Therefore, compared to existing technologies, in the micro-light-emitting structure 001 of this application, the intensity and optical path of the light emitted from the stepped structure 210 decrease when it passes through the transparent substrate 100; the intensity and optical path of the light entering the transparent substrate 100 after passing through the sidewall of the stepped structure 210 also decrease. This is beneficial for improving the contrast of the micro-light-emitting structure 001 and the micro-light-emitting device, and narrowing the field of view. In practical applications, displays with different contrast ratios can also be manufactured by controlling the thickness of the refractive layer according to different display scenarios.

[0044] The above are merely embodiments of this application and are not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A micro-luminescent structure, characterized in that, It includes: A transparent substrate, wherein a semiconductor layer is disposed on the surface of the transparent substrate; The semiconductor layer extends outward from a portion of its surface away from the transparent substrate, forming multiple stepped structures for emitting light, with channels formed between adjacent stepped structures; The semiconductor layer is covered by a refractive layer in the region of the channel. The refractive index of the refractive layer is less than that of the semiconductor layer, and the light absorption rate of the refractive layer is greater than that of the semiconductor layer.

2. The micro-light-emitting structure according to claim 1, characterized in that, The semiconductor layer is an N-type GaN layer, and the refractive layer is a Ti layer.

3. The micro-light-emitting structure according to claim 1, characterized in that, The thickness of the refractive layer is 3nm to 100nm.

4. The micro-light-emitting structure according to any one of claims 1 to 3, characterized in that, The refractive index of the refractive layer is 0.1 to 0.5 higher than that of the semiconductor layer.

5. The micro-light-emitting structure according to any one of claims 1 to 3, characterized in that, The light absorption rate of the refractive layer is 20% to 90%.

6. The micro-light-emitting structure according to claim 1, characterized in that, The stepped structure includes a quantum well layer for emitting light, the quantum well layer being at a distance of R1 from the transparent substrate, and the refractive layer being at a distance of R2 from the transparent substrate, where R1 < R2.

7. The micro-light-emitting structure according to claim 1, characterized in that, The cross-section of the stepped structure is trapezoidal, and the plane containing the upper base of the trapezoid is far from the transparent substrate.

8. The micro-light-emitting structure according to claim 1, characterized in that, The thickness of the transparent substrate is 0.5 μm to 5 μm.

9. The micro-light-emitting structure according to claim 1, characterized in that, The height of the stepped structure is 0.5μm to 2.5μm.

10. A miniature light-emitting device, characterized in that, It includes the microluminescent structure as described in any one of claims 1 to 9.

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