LED chip and light-emitting device

Abstract

The invention provides an LED chip and light-emitting equipment, and relates to the technical field of LEDs. The structure parameters of the LED chip comprise the distance between the bottom of the N electrode and the side wall of the Mesa step structure, the height of the Mesa step structure, the height of the N electrode and the side wall angle of the side, facing the Mesa step structure, of the N electrode. Compared with the prior art, the technical scheme of the invention does not involve additional process steps, and according to the structure of the LED chip, only at least one structural parameter in the structural parameters of the LED chip needs to be optimized, so that the light reflection frequency between the N electrode and the Mesa step structure can be reduced, the light loss of the N electrode is reduced, and the light emitting efficiency is improved. The implementation scheme is simple, and the luminous efficiency of the LED chip can be improved.

Description

Technical Field

[0001] The present application relates to the field of LED technology, and in particular to an LED chip and a light-emitting device. Background Art

[0002] LED (light emitting diode) is a widely used lighting fixture in the world market. It has the advantages of small size, high brightness, low power consumption, low heat generation, long service life, environmental protection, etc. It also has a variety of colors and is deeply loved by consumers. At the same time, LED chips play an indispensable role as backlight sources in electronic products such as mobile phones and televisions that require display screens. As the size of electronic products continues to shrink, the size of LED chips is also required to be greatly reduced. Therefore, major LED chip manufacturers in the world have been committed to developing high-light-efficiency chip structures.

[0003] However, the light energy generated by the recombination of carriers in the LED chip is often lost due to multiple reflections and absorptions inside the LED chip, resulting in a decrease in the luminous efficiency of the final LED chip. In the prior art, the solutions for improving the luminous efficiency include: surface roughening, increasing the reflectivity of the reflective layer, reducing the total reflection at the interface, etc. Although these solutions can effectively improve the luminous efficiency of the LED chip, the implementation plans are often relatively complicated. For example, surface roughening involves processing techniques such as micro-nano etching; increasing the reflectivity of the reflective layer may involve the deposition and surface passivation of reflective metals such as Ag and Al; reducing the total reflection at the interface often requires the introduction of an inorganic passivation layer with a high refractive index such as SiN, etc.

[0004] Therefore, how to provide a technology with a simple implementation scheme and capable of improving the luminous efficiency of LED chips by optimizing the structure of LED chips is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] In view of the above problems, the present application provides an LED chip and a light-emitting device, which achieves the purpose of simple implementation and can improve the light-emitting efficiency of the LED chip. The specific solution is as follows:

[0006] In a first aspect, the present application provides an LED chip, the LED chip comprising:

[0007] substrate;

[0008] An epitaxial wafer located on one side of the substrate, the epitaxial wafer comprising an N-type semiconductor layer, a multi-quantum well layer and a P-type semiconductor layer stacked in sequence on the substrate;

[0009] The epitaxial wafer has a groove, and the groove exposes a portion of the surface of the N-type semiconductor layer to form a Mesa step structure on the epitaxial wafer;

[0010] an N electrode located in the groove;

[0011] The structural parameters of the LED chip include the distance between the bottom of the N electrode and the side wall of the Mesa step structure, the height of the Mesa step structure, the height of the N electrode, and the side wall angle of the N electrode facing the Mesa step structure.

[0012] At least one of the structural parameters of the LED chip is optimized to reduce the number of light reflections between the N electrode and the Mesa step structure.

[0013] Preferably, in the above-mentioned LED chip, at least one of the structural parameters of the LED chip is optimized based on the performance parameters of the LED chip.

[0014] Preferably, in the above-mentioned LED chip, the performance parameter of the LED chip is current density;

[0015] When the current density is less than 0.1 mA / mil 2 When the distance between the bottom of the N electrode and the side wall of the Mesa step structure is in the range of 9 μm to 15 μm.

[0016] Preferably, in the above-mentioned LED chip, the performance parameter of the LED chip is current density;

[0017] When the current density is greater than or equal to 0.1 mA / mil 2 , and less than or equal to 0.2mA / mil 2 When the distance between the bottom of the N electrode and the side wall of the Mesa step structure is in the range of 6 μm to 12 μm.

[0018] Preferably, in the above-mentioned LED chip, the performance parameter of the LED chip is current density;

[0019] When the current density is greater than 0.2 mA / mil 2 When the distance between the bottom of the N electrode and the side wall of the Mesa step structure is in the range of 3 μm to 9 μm.

[0020] Preferably, in the above-mentioned LED chip, the performance parameter of the LED chip is current density;

[0021] When the current density is less than 0.2 mA / mil 2 When the N electrode has a height ranging from 16000 angstroms to 20000 angstroms.

[0022] Preferably, in the above-mentioned LED chip, the performance parameter of the LED chip is current density;

[0023] When the current density is less than 0.2 mA / mil 2 When the sidewall angle of the N electrode facing the Mesa step structure is in the range of 50°-70°.

[0024] Preferably, in the above-mentioned LED chip, the performance parameter of the LED chip is current density;

[0025] When the current density is greater than or equal to 0.2 mA / mil 2 When the N electrode has a height ranging from 25000 angstroms to 30000 angstroms.

[0026] Preferably, in the above-mentioned LED chip, the performance parameter of the LED chip is current density;

[0027] When the current density is greater than or equal to 0.2 mA / mil 2 When the sidewall angle of the N-electrode facing the Mesa step structure is in the range of 70°-90°.

[0028] Preferably, in the above LED chip, the height of the Mesa step structure ranges from 11000 angstroms to 13000 angstroms.

[0029] A second aspect of the present application provides a light-emitting device, which includes the LED chip described in any one of the above items.

[0030] By means of the above technical solution, the present application provides an LED chip and a light-emitting device, wherein the structural parameters of the LED chip include the distance between the bottom of the N electrode and the side wall of the Mesa step structure, the height of the Mesa step structure, the height of the N electrode, and the side wall angle of the N electrode facing the Mesa step structure. Compared with the prior art, the technical solution of the present application does not involve additional process steps. According to the structure of the LED chip, only at least one of the structural parameters of the LED chip needs to be optimized to reduce the number of light reflections between the N electrode and the Mesa step structure, reduce the light loss of the N electrode, and achieve the purpose of simple implementation and improving the luminous efficiency of the LED chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0032] Figure 1 A schematic diagram of the structure of an LED chip provided by an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of the structure of another LED chip provided by an embodiment of the present invention;

[0034] Figure 3 A schematic diagram of a process for preparing an LED chip provided by an embodiment of the present invention;

[0035] Figure 4-Figure 8 for Figure 3 Schematic diagram of the partial structure corresponding to the preparation method shown. DETAILED DESCRIPTION

[0036] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation mode of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application. It is known to those skilled in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0037] It should be noted that the directional words appearing in the present invention are based on the relative position relationship shown in the drawings and cannot be used as an absolute limitation to the present application.

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] refer to Figure 1 , Figure 1 The schematic diagram of the structure of an LED chip provided by the embodiment of the present invention is as follows: The LED chip provided by the embodiment of the present invention comprises: a substrate 11 .

[0040] The epitaxial wafer is located on one side of the substrate 11 , and the epitaxial wafer includes an N-type semiconductor layer 12 , a multi-quantum well layer 13 , and a P-type semiconductor layer 14 which are sequentially stacked on the substrate 11 .

[0041] The epitaxial wafer has a groove 15 , and the groove 15 exposes a portion of the surface of the N-type semiconductor layer 12 to form a Mesa step structure on the epitaxial wafer.

[0042] The N electrode 16 is located in the groove 15 .

[0043] The structural parameters of the LED chip include the distance L between the bottom of the N electrode 16 and the side wall of the Mesa step structure, the height H1 of the Mesa step structure, the height H2 of the N electrode 16, and the side wall angle β of the N electrode 16 facing the Mesa step structure.

[0044] At least one of the structural parameters of the LED chip is optimized to reduce the number of light reflections between the N electrode 16 and the Mesa step structure.

[0045] It should be noted that the height of the Mesa step structure can also be understood as the depth of the groove 15 to a certain extent.

[0046] Specifically, in the embodiment of the present invention, the structural parameters of the LED chip include the distance L between the bottom of the N electrode 16 and the side wall of the Mesa step structure, the height H1 of the Mesa step structure, the height H2 of the N electrode 16, and the side wall angle β of the N electrode 16 facing the Mesa step structure. Compared with the prior art, the technical solution of the present application does not involve additional process steps. According to the structure of the LED chip, only at least one of the structural parameters of the LED chip needs to be optimized to reduce the number of light reflections between the N electrode 16 and the Mesa step structure, reduce the light loss of the N electrode 16, and achieve the purpose of simple implementation and improving the luminous efficiency of the LED chip.

[0047] In an optional embodiment of the present invention, at least one of the structural parameters of the LED chip is optimized based on the performance parameters of the LED chip.

[0048] In an optional embodiment of the present invention, the performance parameter of the LED chip is current density.

[0049] When the current density is less than 0.1 mA / mil 2 When the distance between the bottom of the N electrode 16 and the side wall of the Mesa step structure is in the range of 9 μm-15 μm, that is, 9 μm≤L≤15 μm.

[0050] When the current density is greater than or equal to 0.1 mA / mil 2 , and less than or equal to 0.2mA / mil 2 When the distance between the bottom of the N electrode 16 and the side wall of the Mesa step structure is in the range of 6 μm-12 μm, that is, 6 μm≤L≤12 μm.

[0051] When the current density is greater than 0.2 mA / mil 2When the distance between the bottom of the N electrode and the side wall of the Mesa step structure is in the range of 3 μm-9 μm, that is, 3 μm≤L≤9 μm.

[0052] Specifically, the technical effects that can be achieved by the technical solution of the present application are explained in a comparative manner in the embodiments of the present invention.

[0053] In the comparative example, the distance between the bottom of the N electrode and the side wall of the Mesa step structure is 5 μm, the height of the Mesa step structure is 14,000 angstroms, the height of the N electrode is 30,000 angstroms, and the side wall angle of the N electrode facing the Mesa step structure is 80°.

[0054] In a specific embodiment, the distance L between the bottom of the N electrode 16 and the side wall of the Mesa step structure is 7 μm, the height H1 of the Mesa step structure is 14,000 angstroms, the height H2 of the N electrode 16 is 30,000 angstroms, and the side wall angle β of the N electrode 16 facing the Mesa step structure is 80°.

[0055] Through actual testing, the current density of the LED chip is 0.1mA / mil 2 When the distance L between the bottom of the N electrode 16 and the side wall of the Mesa step structure is adjusted from 5 μm to 7 μm, the luminous efficiency of the prepared LED chip is increased by 0.8%.

[0056] In an optional embodiment of the present invention, the performance parameter of the LED chip is current density.

[0057] When the current density is less than 0.2 mA / mil 2 When the height of the N electrode 16 is in the range of 16000 angstroms to 20000 angstroms, that is, 16000 angstroms ≤ H2 ≤ 20000 angstroms.

[0058] When the current density is greater than or equal to 0.2 mA / mil 2 When the height of the N electrode 16 is in the range of 25000 angstroms to 30000 angstroms, that is, 25000 angstroms ≤ H2 ≤ 30000 angstroms.

[0059] Specifically, the technical effects that can be achieved by the technical solution of the present application are explained in a comparative manner in the embodiments of the present invention.

[0060] In the comparative example, the distance between the bottom of the N electrode and the side wall of the Mesa step structure is 5 μm, the height of the Mesa step structure is 14,000 angstroms, the height of the N electrode is 30,000 angstroms, and the side wall angle of the N electrode facing the Mesa step structure is 80°.

[0061] In a specific embodiment, the distance L between the bottom of the N electrode 16 and the side wall of the Mesa step structure is 5 μm, the height H1 of the Mesa step structure is 14,000 angstroms, the height H2 of the N electrode 16 is 18,000 angstroms, and the side wall angle β of the N electrode 16 facing the Mesa step structure is 80°.

[0062] Through actual testing, the current density of the LED chip is 0.05mA / mil 2 When the height H2 of the N electrode 16 is adjusted from 30,000 angstroms to 18,000 angstroms, the luminous efficiency of the prepared LED chip is increased by 0.5%.

[0063] In an optional embodiment of the present invention, the performance parameter of the LED chip is current density.

[0064] When the current density is less than 0.2 mA / mil 2 When the sidewall angle of the N electrode facing the Mesa step structure is in the range of 50°-70°, that is, 50°≤β≤70°.

[0065] When the current density is greater than or equal to 0.2 mA / mil 2 When the sidewall angle of the N-electrode facing the Mesa step structure is in the range of 70°-90°, that is, 70°≤β≤90°.

[0066] Specifically, the technical effects that can be achieved by the technical solution of the present application are explained in a comparative manner in the embodiments of the present invention.

[0067] In the comparative example, the distance between the bottom of the N electrode and the side wall of the Mesa step structure is 5 μm, the height of the Mesa step structure is 14,000 angstroms, the height of the N electrode is 30,000 angstroms, and the side wall angle of the N electrode facing the Mesa step structure is 80°.

[0068] In a specific embodiment, the distance L between the bottom of the N electrode 16 and the side wall of the Mesa step structure is 5 μm, the height H1 of the Mesa step structure is 14,000 angstroms, the height H2 of the N electrode 16 is 30,000 angstroms, and the side wall angle β of the N electrode 16 facing the Mesa step structure is 60°.

[0069] Through actual testing, the current density of the LED chip is 0.05mA / mil 2 When the side wall angle β of the N electrode 16 facing the Mesa step structure is adjusted from 80° to 60°, the luminous efficiency of the prepared LED chip is increased by 0.4%.

[0070] In an optional embodiment of the present invention, the height H1 of the Mesa step structure ranges from 11000 angstroms to 13000 angstroms.

[0071] Specifically, the technical effects that can be achieved by the technical solution of the present application are explained in a comparative manner in the embodiments of the present invention.

[0072] In the comparative example, the distance between the bottom of the N electrode and the side wall of the Mesa step structure is 5 μm, the height of the Mesa step structure is 14,000 angstroms, the height of the N electrode is 30,000 angstroms, and the side wall angle of the N electrode facing the Mesa step structure is 80°.

[0073] In a specific embodiment, the distance L between the bottom of the N electrode 16 and the side wall of the Mesa step structure is 5 μm, the height H1 of the Mesa step structure is 12,000 angstroms, the height H2 of the N electrode 16 is 30,000 angstroms, and the side wall angle β of the N electrode 16 facing the Mesa step structure is 80°.

[0074] Through actual testing, the current density of the LED chip is 0.08mA / mil 2 When the height of the Mesa step structure H1 is adjusted from 14000 angstroms to 12000 angstroms, the luminous efficiency of the prepared LED chip is increased by 0.3%.

[0075] From the above description, it can be seen that the technical solution of the present application is to improve the luminous efficiency of the LED chip by optimizing the structural design of the LED chip without adding any additional production processes. The implementation of the technical solution of the present application can be completed based on the existing equipment and raw materials for LED chip production, thereby reducing the number of light reflections between the N electrode 16 and the Mesa step structure, reducing the light loss of the N electrode 16, and ultimately achieving the purpose of a simple implementation plan and improving the luminous efficiency of the LED chip.

[0076] It should be noted that the technical solution of the present application is aimed at high-efficiency LED chips operating at low current density. After optimization of the technical solution of the present application, the luminous efficiency of the LED chip can be increased by 0.3%-1.0%.

[0077] In an optional embodiment of the present invention, reference Figure 2 , Figure 2 A schematic diagram of the structure of another LED chip provided by an embodiment of the present invention. The LED chip provided by an embodiment of the present invention also includes:

[0078] The current spreading layer 17 is located on the side of the P-type semiconductor layer 14 facing away from the substrate 11 .

[0079] A current blocking layer 18 and a P-electrode 19 are located on the side of the current spreading layer 17 facing away from the substrate 11 .

[0080] Specifically, in the embodiment of the present invention, the material of the current spreading layer 17 includes but is not limited to ITO material, the material of the current blocking layer 18 includes but is not limited to SiO2 material, the material of the P electrode 19 may be the same as or different from the material of the N electrode 16, and the electrode material includes but is not limited to metal material.

[0081] It should be noted that the LED chip provided in the embodiment of the present invention may also include other functional film layers, such as a surface passivation layer and functional film layers such as a DBR reflector. Since these functional film layers are not improved in the present application, they will not be described in detail here. Only the current expansion layer 17, the current blocking layer 18 and the P electrode 19 are exemplified.

[0082] Based on the above embodiment of the present invention, another embodiment of the present invention further provides a method for preparing an LED chip, referring to Figure 3 , Figure 3 A schematic flow chart of a method for preparing an LED chip provided in an embodiment of the present invention. The method for preparing an LED chip provided in an embodiment of the present invention comprises:

[0083] S101: Figure 4 As shown, a substrate 11 is provided.

[0084] S102: Figure 5 As shown, an epitaxial wafer is formed on one side of the substrate 11 , and the epitaxial wafer includes an N-type semiconductor layer 12 , a multi-quantum well layer 13 , and a P-type semiconductor layer 14 which are sequentially stacked on the substrate 11 .

[0085] S103: Figure 6 As shown, the epitaxial wafer is processed so that the epitaxial wafer has a groove 15, and the groove 15 exposes a portion of the surface of the N-type semiconductor layer 12 to form a Mesa step structure on the epitaxial wafer.

[0086] Specifically, this step includes but is not limited to using a mixed solution of sulfuric acid and hydrogen peroxide to Figure 5 The prepared epitaxial wafer is cleaned, and then the epitaxial wafer is etched to form a Mesa step structure.

[0087] S104: Figure 7 As shown, a current spreading layer 17 is formed on a side of the P-type semiconductor layer 14 facing away from the substrate 11 .

[0088] Specifically, this step includes but is not limited to preparing the patterned current spreading layer 17 by deposition, photolithography, etching and the like.

[0089] S105: Figure 8 As shown, a current blocking layer 18 is formed on the side of the current spreading layer 17 facing away from the substrate 11 .

[0090] Specifically, this step includes but is not limited to preparing the patterned current blocking layer 18 by deposition, photolithography, etching and the like.

[0091] S106: Figure 2 As shown, an N electrode 16 and a P electrode 19 are prepared, wherein the N electrode 16 is located in the groove 15, and the P electrode 19 is located on the side of the current spreading layer 17 away from the substrate 11; wherein the structural parameters of the LED chip include a distance L between the bottom of the N electrode 16 and the side wall of the Mesa step structure, a height H1 of the Mesa step structure, a height H2 of the N electrode 16, and a side wall angle β of the N electrode 16 facing the Mesa step structure; at least one of the structural parameters of the LED chip is optimized to reduce the number of light reflections between the N electrode 16 and the Mesa step structure.

[0092] Specifically, this step includes but is not limited to preparing the N electrode 16 and the P electrode 19 by using a negative resist lift-off process.

[0093] Based on the above embodiment of the present invention, a light-emitting device is provided in another embodiment of the present invention. The light-emitting device includes the LED chip described in the above embodiment.

[0094] The above is a detailed introduction to an LED chip and a light-emitting device provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0095] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0096] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements is inherent to the elements, or also includes elements inherent to these processes, methods, articles or devices. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0097] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An LED chip, characterized in that: The LED chip comprises: substrate; An epitaxial wafer located on one side of the substrate, the epitaxial wafer comprising an N-type semiconductor layer, a multi-quantum well layer and a P-type semiconductor layer stacked in sequence on the substrate; The epitaxial wafer has a groove, and the groove exposes a portion of the surface of the N-type semiconductor layer to form a Mesa step structure on the epitaxial wafer; An N electrode located in the groove; wherein the structural parameters of the LED chip include the distance between the bottom of the N electrode and the side wall of the Mesa step structure, the height of the Mesa step structure, the height of the N electrode, and the side wall angle of the N electrode facing the Mesa step structure; At least one of the structural parameters of the LED chip is optimized to reduce the number of light reflections between the N electrode and the Mesa step structure.

2. The LED chip according to claim 1, characterized in that: At least one of the structural parameters of the LED chip is optimized based on the performance parameters of the LED chip.

3. The LED chip according to claim 2, characterized in that: The performance parameter of the LED chip is current density; When the current density is less than 0.1 mA / mil 2 When the distance between the bottom of the N electrode and the side wall of the Mesa step structure is in the range of 9 μm to 15 μm.

4. The LED chip according to claim 2, characterized in that: The performance parameter of the LED chip is current density; When the current density is greater than or equal to 0.1 mA / mil 2 , and less than or equal to 0.2mA / mil 2 When the distance between the bottom of the N electrode and the side wall of the Mesa step structure is in the range of 6 μm to 12 μm.

5. The LED chip according to claim 2, characterized in that: The performance parameter of the LED chip is current density; When the current density is greater than 0.2 mA / mil 2 When the distance between the bottom of the N electrode and the side wall of the Mesa step structure is in the range of 3 μm to 9 μm.

6. The LED chip according to claim 2, characterized in that: The performance parameter of the LED chip is current density; When the current density is less than 0.2 mA / mil 2 When the N electrode has a height ranging from 16000 angstroms to 20000 angstroms.

7. The LED chip according to claim 2, characterized in that: The performance parameter of the LED chip is current density; When the current density is less than 0.2 mA / mil 2 When the sidewall angle of the N electrode facing the Mesa step structure is in the range of 50°-70°.

8. The LED chip according to claim 2, characterized in that: The performance parameter of the LED chip is current density; When the current density is greater than or equal to 0.2 mA / mil 2 When the N electrode has a height ranging from 25000 angstroms to 30000 angstroms.

9. The LED chip according to claim 2, characterized in that: The performance parameter of the LED chip is current density; When the current density is greater than or equal to 0.2 mA / mil 2 When the sidewall angle of the N-electrode facing the Mesa step structure is in the range of 70°-90°.

10. The LED chip according to any one of claims 1 to 9, characterized in that: The height of the Mesa step structure ranges from 11000 angstroms to 13000 angstroms.

11. A light emitting device, characterized in that: The light emitting device comprises the LED chip according to any one of claims 1-10.

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