Composite substrate and high-brightness LED epitaxial wafer
By using composite substrate and patterned dielectric layer in GaN-based LEDs, the lattice mismatch problem between the substrate and the epitaxial layer is solved, the crystal quality and brightness of the LED are improved, the leakage problem is reduced, and more efficient light is achieved Reflect and glow.
Patent Information
- Application Number
- CN202420750251.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-11
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2034-04-11
AI Technical Summary
During the epitaxial growth process of GaN-based semiconductor materials, due to the mismatch between the lattice and thermal expansion of the substrate and the epitaxial layer, the dislocation density and high stress are affected, which affects the efficiency and life of the device. It is difficult for the prior art to effectively improve the luminous intensity and light efficiency of LEDs. .
A composite substrate is adopted, including a layered substrate and a patterned dielectric layer, the substrate surface has a micro-protrusion and micro-grooving structure, and the patterned dielectric layer is composed of multiple dielectric layers, through refractive index differences and lattice overacting. Reduce stress and introduce silicon nitride and silicon oxide layers to improve crystal quality and light reflection.
The crystal quality of the Group III nitride buffer layer is improved, the defects and leakage channels of the epitaxial layer are reduced, the forward light outflow of light is enhanced, and the brightness and life of the LED are improved.
Smart Images
Figure CN222261106U_ABST
Abstract
Description
Technical Field
[0001] The utility model particularly relates to a composite substrate and a high-brightness LED epitaxial wafer, belonging to the technical field of optoelectronic devices. Background Art
[0002] GaN-based light-emitting diodes (LEDs) have the advantages of long life, low energy consumption, small size, and high reliability. They have become the most promising lighting source and an important trend in leading lighting technology. However, there are still problems with low luminous intensity and efficiency. Further improving the luminous intensity and light efficiency of LEDs is the goal of the development of LED lighting technology.
[0003] At present, GaN-based semiconductor material MOCVD epitaxy is an epitaxial growth technology on heterogeneous substrates. Due to the lattice and thermal expansion mismatch between the substrate and the epitaxial layer, the epitaxially grown crystal material has a high dislocation density and high stress. These dislocations appear as non-radiative recombination centers when the device is working and affect the device efficiency. At the same time, they cause the leakage current to increase and the device to age rapidly, affecting the working efficiency and life of the device, which restricts the application of LED high-end lighting display field.
[0004] The currently widely used substrate patterning technology can improve the light extraction efficiency. Therefore, how to use the patterned substrate technology to further improve the light extraction efficiency of LEDs has become a hot topic in industry research and is of great significance to the market promotion and application of LEDs. Utility Model Content
[0005] The main purpose of the utility model is to provide a composite substrate and a high-brightness LED epitaxial wafer, thereby overcoming the deficiencies in the prior art.
[0006] In order to achieve the above-mentioned utility model purpose, the technical solution adopted by the utility model includes:
[0007] The utility model provides a composite substrate, comprising a laminated substrate and a patterned dielectric layer, wherein the surface of the substrate has a patterned structure formed by at least one micro-protrusion and / or micro-groove, and the patterned dielectric layer is continuously covered on the surface of the substrate.
[0008] The patterned dielectric layer includes a first dielectric layer, a second dielectric layer, a transition layer and a third dielectric layer which are sequentially stacked along a selected direction on the surface of the substrate, and the refractive index of the third dielectric layer is smaller than that of the second dielectric layer.
[0009] Furthermore, the graphic structure includes a plurality of micro-protrusions, the plurality of micro-protrusions are distributed at intervals, and the micro-grooves are formed between adjacent micro-protrusions, wherein the radial width of the micro-protrusions gradually decreases in a direction away from the substrate.
[0010] Furthermore, the radial width of the bottom of the micro-protrusion is 0.5-2 μm, and the height is 0.1-0.5 μm.
[0011] Furthermore, the spacing between adjacent micro-protrusions is 0.1-1 μm.
[0012] Furthermore, the first dielectric layer includes a silicon oxide layer.
[0013] Furthermore, the thickness of the first dielectric layer is 10-100 nm.
[0014] Furthermore, the second dielectric layer includes a Si—XN layer, where X is any one of O, S, P, F, and Cl.
[0015] Furthermore, the thickness of the second dielectric layer is 5-50 nm.
[0016] Furthermore, the transition layer includes at least one silicon nitride layer and at least one silicon oxide layer stacked along the selected direction.
[0017] Furthermore, the transition layer includes a plurality of silicon nitride layers and a plurality of silicon oxide layers which are alternately stacked in sequence along the selected direction.
[0018] Furthermore, a first layer in the transition layer close to the second dielectric layer and a last layer far from the second dielectric layer are both silicon nitride layers.
[0019] Furthermore, the thickness of each silicon nitride layer is 1 to 5 nm, and the thickness of each silicon oxide layer is 1 to 5 nm.
[0020] Furthermore, the third dielectric layer includes a silicon oxide layer.
[0021] Furthermore, the thickness of the third dielectric layer is 5-20 nm.
[0022] Furthermore, the patterned dielectric layer has a contour structure that is the same as or similar to the pattern structure.
[0023] Furthermore, the first dielectric layer, the second dielectric layer, the transition layer and the third dielectric layer all have a contour structure that is the same as or similar to the graphic structure.
[0024] On the other hand, the utility model further provides a high-brightness LED epitaxial wafer, comprising a substrate and an epitaxial layer stacked along the selected direction, wherein the substrate is the composite substrate, and the epitaxial layer is stacked on the third dielectric layer.
[0025] Furthermore, the high-brightness LED epitaxial wafer further includes: a buffer layer, the buffer layer is stacked on the third dielectric layer, and the epitaxial layer is stacked on the buffer layer, wherein the surface of the buffer layer facing away from the composite substrate is continuous and flat.
[0026] Compared with the prior art, the utility model provides a high-brightness LED epitaxial wafer, which improves the lateral epitaxy of the III-nitride buffer layer by arranging a graphic structure and a graphic dielectric layer on the substrate body, thereby improving the crystal quality of the III-nitride buffer layer, reducing the defects inside the epitaxial layer in the LED epitaxial wafer, reducing the non-radiative composite leakage channel, improving the leakage problem, and providing light redirection by introducing a graphic dielectric layer, and ensuring the total reflection of the light emitted from the nitride light-emitting layer toward the substrate before reaching the substrate interface, thereby improving the brightness of the LED epitaxial wafer. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0028] Figure 1 This is a structural schematic diagram of a high-brightness LED epitaxial wafer provided in a typical implementation case of the utility model;
[0029] Figure 2 It is a structural schematic diagram of a transition layer in a high-brightness LED epitaxial wafer provided in a typical implementation case of the utility model. DETAILED DESCRIPTION
[0030] In view of the deficiencies in the prior art, the inventor of this case has proposed the technical solution of the utility model after long-term research and extensive practice. The technical solution, its implementation process and principle will be further explained as follows.
[0031] Example
[0032] See also Figure 1 A high-brightness LED epitaxial wafer comprises a substrate 10, a patterned dielectric layer 20, a III-nitride buffer layer 30 and a III-nitride epitaxial layer 40 which are sequentially stacked along a selected direction, wherein the substrate 10 and the patterned dielectric layer 20 serve as a composite substrate, wherein the selected direction is the longitudinal direction of the high-brightness LED epitaxial wafer.
[0033] Specifically, the substrate includes a substrate body 11 and a graphic structure, which includes a plurality of micro-protrusions 12 arranged on the surface of the substrate body 11, the plurality of micro-protrusions 12 are distributed at intervals, and micro-grooves are formed between adjacent micro-protrusions 12 (the micro-grooves are formed by enclosing a plurality of micro-protrusions and the substrate body), wherein the radial width / radial cross-sectional area of the micro-protrusions 12 gradually decreases in the direction away from the substrate body 11.
[0034] It should be noted that the substrate 10 is a patterned substrate, and the function of the patterned substrate is basically the same as that known to those skilled in the art, and is not the focus of this case. Exemplarily, the micro-protrusion 12 can be a prismatic structure, a prism structure, a cylindrical structure, a pyramidal structure, a conical structure, a hemispherical or spherical-like structure, etc.
[0035] Specifically, the radial width of the bottom of the micro-protrusion 12 is 0.5-2 μm, the height is 0.1-0.5 μm, and the spacing between adjacent micro-protrusions is 0.1-1 μm. It should be noted that the radial direction of the micro-protrusion is perpendicular to the selected direction.
[0036] Specifically, the patterned dielectric layer 20 is continuously coated on the surface of the substrate 10. It can be understood that the surface is a surface with a pattern structure, that is, the patterned dielectric layer 20 is continuously coated on the surface of the substrate body 11 and the micro-protrusions 12. Specifically, the patterned dielectric layer 20 includes a first dielectric layer 21, a second dielectric layer 22, a transition layer 23, and a third dielectric layer 24 which are sequentially stacked on the surface of the substrate 10 along a selected direction, and the refractive index of the third dielectric layer 24 is less than the refractive index of the second dielectric layer 22.
[0037] Specifically, the thickness of the patterned dielectric layer 20 is uniform and has a contour structure that is the same as or similar to the graphic structure. More specifically, the thickness of each of the first dielectric layer 21, the second dielectric layer 22, the transition layer 23 and the third dielectric layer 24 is uniform, and the first dielectric layer 21, the second dielectric layer 22, the transition layer 23 and the third dielectric layer 24 all have a contour structure that is the same as or similar to the graphic structure.
[0038] Specifically, the first dielectric layer 21 is a silicon oxide layer, and the thickness of the first dielectric layer 21 is 10-100 nm; the second dielectric layer 22 includes a Si-XN layer, X is any one of O, S, P, F, and Cl, and the thickness of the second dielectric layer 22 is 5-50 nm.
[0039] For details, please refer to Figure 2The transition layer 23 includes at least one silicon nitride layer 231 and at least one silicon oxide layer 232 stacked along a selected direction. More specifically, the transition layer 23 includes a plurality of silicon nitride layers 231 and a plurality of silicon oxide layers 232 stacked alternately in sequence along a selected direction, wherein the first layer of the transition layer 23 close to the second dielectric layer 22 and the last layer away from the second dielectric layer 22 are both silicon nitride layers 231, the thickness of each silicon nitride layer 231 is 1 to 5 nm, and the thickness of each silicon oxide layer 232 is 1 to 5 nm.
[0040] Specifically, the third dielectric layer 24 is a silicon oxide layer, and the thickness of the third dielectric layer 24 is 5-20 nm.
[0041] Specifically, the first dielectric layer directly stacked on the substrate enhances the total reflection of light emitted from the nitride light-emitting layer toward the substrate at the interface of the first dielectric layer, thereby improving the forward light emission of the LED epitaxial wafer; the second dielectric layer passivates a large number of dangling bonds on the surface of the first dielectric layer; and the X atoms in the Si-XN layer enhance the electron capture capability, thereby reducing the movement of electrons near the substrate and improving the leakage problem of the LED epitaxial wafer.
[0042] Specifically, the periodically overlapping silicon nitride layer and silicon oxide layer can act on the lattice transition between the second dielectric layer and the third dielectric layer, and can gradually release the stress caused by the lattice difference between the second dielectric layer and the third dielectric layer, thereby reducing the internal stress of the third dielectric layer; at the same time, the third dielectric layer has a lower refractive index than the second dielectric layer, and the third dielectric layer increases the refractive index difference between the nitride buffer layer and the substrate, further enhancing the total reflection of the light from the nitride light-emitting layer toward the substrate at the interface of the first dielectric layer, thereby improving the forward light output of the LED epitaxial wafer.
[0043] Specifically, the III-nitride buffer layer 30 is stacked on the third dielectric layer 24 , and the surface of the III-nitride buffer layer 30 facing away from the substrate is continuous and flat.
[0044] Specifically, the thickness of the III-nitride buffer layer 30 is 1-5 μm, and the III-nitride buffer layer 30 may be a GaN buffer layer or the like.
[0045] Specifically, the III-nitride epitaxial layer 40 includes an n-type semiconductor layer 41, a light emitting layer 42, and a p-type semiconductor layer 43 stacked in a selected direction. The n-type semiconductor layer 41 may be an n-type Al x Ga 1-x N layer, 0≤x≤1, the n-type semiconductor layer 41 can be Si-doped, and the doping concentration of the n-type semiconductor layer 41 is 1×10 18 cm -3 ~8×10 18 cm-3 Specifically, the thickness of the n-type semiconductor layer 41 is 2 to 10 μm.
[0046] Specifically, the light-emitting layer 42 may include 2 to 10 periodic cycles of overlapping growth of a quantum well layer with a thickness of 1 to 6 nm and a quantum barrier layer with a thickness of 6 to 25 nm; the quantum well layer and the quantum barrier layer are both group III nitride structure layers, and illustratively, the quantum well layer may be an InGaN well layer, a GaN well layer or an AlGaN well layer, and the quantum barrier layer may be an InGaN barrier layer, a GaN barrier layer or an AlGaN barrier layer.
[0047] Specifically, the p-type semiconductor layer 43 may be a p-type Al y Ga 1-y N layer, 0≤y≤1, the p-type semiconductor layer 43 may be Mg-doped, and the doping concentration of the p-type semiconductor layer 43 is 1×10 19 cm -3 ~1×10 21 cm -3 Specifically, the thickness of the p-type semiconductor layer 43 is 20 to 300 nm.
[0048] The utility model provides a high-brightness LED epitaxial wafer, which improves the lateral epitaxy of the III-nitride buffer layer by arranging a graphic structure and a graphic dielectric layer on a substrate body, thereby improving the crystal quality of the III-nitride buffer layer, reducing the defects inside the epitaxial layer in the LED epitaxial wafer, reducing the non-radiative composite leakage channel, improving the leakage problem, and providing light redirection by introducing a graphic dielectric layer, ensuring the total reflection of the light emitted from the nitride light-emitting layer toward the substrate before reaching the substrate interface, thereby improving the brightness of the LED epitaxial wafer.
[0049] It should be understood that the above embodiments are only for illustrating the technical concept and features of the utility model, and their purpose is to enable people familiar with the technology to understand the content of the utility model and implement it accordingly, and they cannot be used to limit the protection scope of the utility model. Any equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.
Claims
1. A composite substrate, comprising a stacked substrate and a patterned dielectric layer, wherein the surface of the substrate has a pattern structure formed by at least one micro-protrusion and / or micro-groove, and the patterned dielectric layer is continuously covered on the surface of the substrate, characterized in that: The patterned dielectric layer includes a first dielectric layer, a second dielectric layer, a transition layer and a third dielectric layer which are sequentially stacked along a selected direction on the surface of the substrate, and the refractive index of the third dielectric layer is smaller than that of the second dielectric layer.
2. The composite substrate according to claim 1, characterized in that: The graphic structure includes a plurality of micro-protrusions, the plurality of micro-protrusions are distributed at intervals, and the micro-grooves are formed between adjacent micro-protrusions, wherein the radial width of the micro-protrusions gradually decreases in a direction away from the substrate.
3. The composite substrate according to claim 2, characterized in that: The radial width of the bottom of the micro-protrusion is 0.5-2 μm, and the height is 0.1-0.5 μm.
4. The composite substrate according to claim 2, characterized in that: The distance between adjacent micro-protrusions is 0.1-1 μm.
5. The composite substrate according to claim 1, characterized in that: The first dielectric layer includes a silicon oxide layer.
6. The composite substrate according to claim 1 or 5, characterized in that: The thickness of the first dielectric layer is 10-100 nm.
7. The composite substrate according to claim 1, characterized in that: The second dielectric layer includes a Si—XN layer, where X is any one of O, S, P, F, and Cl.
8. The composite substrate according to claim 1 or 7, characterized in that: The thickness of the second dielectric layer is 5-50 nm.
9. The composite substrate according to claim 1, characterized in that: The transition layer includes at least one silicon nitride layer and at least one silicon oxide layer stacked along the selected direction.
10. The composite substrate according to claim 9, characterized in that: The transition layer includes a plurality of silicon nitride layers and a plurality of silicon oxide layers which are alternately stacked in sequence along the selected direction.
11. The composite substrate according to claim 10, characterized in that: The first layer of the transition layer close to the second dielectric layer and the last layer far from the second dielectric layer are both silicon nitride layers.
12. The composite substrate according to claim 9, characterized in that: The thickness of each silicon nitride layer is 1-5 nm, and the thickness of each silicon oxide layer is 1-5 nm.
13. The composite substrate according to claim 1, characterized in that: The third dielectric layer includes a silicon oxide layer.
14. The composite substrate according to claim 1 or 13, characterized in that: The thickness of the third dielectric layer is 5-20 nm.
15. A high brightness LED epitaxial wafer, comprising a substrate and an epitaxial layer stacked along the selected direction, characterized in that: The substrate is the composite substrate according to any one of claims 1 to 14, and the epitaxial layer is stacked on the third dielectric layer.
16. The high brightness LED epitaxial wafer according to claim 15, characterized in that: Also includes: A buffer layer is stacked on the third dielectric layer, and the epitaxial layer is stacked on the buffer layer, wherein a surface of the buffer layer facing away from the composite substrate is continuous and flat.