LED epitaxial structure

Abstract

The utility model provides an LED epitaxial structure, which is an epitaxial structure emitting three-color light and specifically comprises a substrate, a plurality of pattern structures are formed on the substrate, each pattern structure is composed of a horizontal plane, a first slope surface and a second slope surface, and acute angles formed between the first slope surface and the horizontal plane and between the second slope surface and the horizontal plane are different; the epitaxial structures are formed on the first slope surface, the second slope surface and the horizontal plane, the epitaxial structure on the first slope surface is a blue light epitaxial structure, the epitaxial structure on the second slope surface is a green light epitaxial structure, and the epitaxial structure on the horizontal plane is a red light epitaxial structure. According to the utility model, the pattern structure with the horizontal plane, the first slope surface and the second slope surface is arranged on the substrate, so that the emission of three-color light can be realized, and the integration process of blue light, green light and red light can be greatly simplified.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductors, in particular to an LED epitaxial structure. Background Art

[0002] Gallium nitride (GaN)-based LEDs (light-emitting diodes) have broad application prospects as a new display technology and have attracted much research and industry attention. GaN is also an ideal short-wavelength luminescent material. By changing the doping of GaN and its compounds, its luminescent spectrum can cover the entire range of visible light, providing broad development prospects for the development of light in different wavelengths and white light, and is currently the focus of global research.

[0003] GaN-based LED is the most important application of GaN materials and is regarded as a new type of lighting source. GaN-based LED has long life, high production efficiency, low power consumption, and is green and environmentally friendly. It is widely used in display, printing, biomedicine and other fields.

[0004] GaN-based blue light epitaxial structure, GaN-based green light epitaxial structure and GaN-based red light epitaxial structure are three conventional GaN-based epitaxial structures. The process of integrating these three epitaxial structures is complicated. Therefore, it is necessary to design an epitaxial structure that can simultaneously realize the emission of blue light, green light and red light. Utility Model Content

[0005] The utility model aims to provide an LED epitaxial structure to reduce the integration process and to achieve the emission of blue light, green light and red light at the same time.

[0006] In order to achieve the above-mentioned purpose and other related purposes, the utility model provides an LED epitaxial structure, which is an epitaxial structure emitting three-color light, specifically comprising:

[0007] A substrate having a plurality of graphic structures formed thereon, each of the graphic structures being composed of a horizontal plane, a first slope plane and a second slope plane, and the acute angles formed between the first slope plane and the second slope plane and the horizontal plane are different;

[0008] The epitaxial structure formed on the first slope surface, the second slope surface and the horizontal surface, wherein the epitaxial structure on the first slope surface is a blue light epitaxial structure, the epitaxial structure on the second slope surface is a green light epitaxial structure, and the epitaxial structure on the horizontal surface is a red light epitaxial structure.

[0009] Optionally, in the LED epitaxial structure, the cross-section of the graphic structure in a direction perpendicular to the substrate surface is an isosceles trapezoid, an isosceles inverted trapezoid, or an isosceles triangle with a horizontal line; the cross-section of the graphic structure in a direction parallel to the substrate surface is a rectangle.

[0010] Optionally, in the LED epitaxial structure, the spacing between adjacent graphic structures ranges from 3μm to 5μm; the height of the graphic structure ranges from 7μm to 10μm, the acute angle formed between the first slope surface and the horizontal plane is 60° to 75°, the acute angle formed between the second slope surface and the horizontal plane is 30° to 45°, and the width of the horizontal plane ranges from 10μm to 20μm.

[0011] Optionally, in the LED epitaxial structure, the thicknesses of the structural layers corresponding to the blue light epitaxial structure, the green light epitaxial structure and the red light epitaxial structure are different, and the smaller the acute angle formed with the horizontal plane, the greater the thickness of the structural layers formed thereon.

[0012] Optionally, in the LED epitaxial structure, the blue light epitaxial structure includes, from bottom to top, a first AlN nucleation layer, a first bottom buffer layer, a blue light first-type semiconductor layer, a first stress buffer layer, a blue light active layer and a blue light second-type semiconductor layer.

[0013] Optionally, the blue light active layer is a periodic structure in which well layers and barrier layers grow alternately, the single-period thickness of the well layers of the blue light active layer is 2nm-2.5nm, and the single-period thickness of the barrier layers of the blue light active layer is 3nm-7nm.

[0014] Optionally, in the LED epitaxial structure, the thickness range of the first AlN nucleation layer is 20nm to 100nm; the thickness range of the first bottom buffer layer is 500nm to 800nm; the thickness range of the blue light first-type semiconductor layer is 500nm to 800nm; the thickness range of the first stress buffer layer is 100nm to 200nm; the thickness range of the blue light second-type semiconductor layer is 33nm to 128nm.

[0015] Optionally, in the LED epitaxial structure, the green light epitaxial structure includes, from bottom to top, a second AlN nucleation layer, a second bottom buffer layer, a green light first-type semiconductor layer, a second stress buffer layer, a green light active layer and a green light second-type semiconductor layer.

[0016] Optionally, the green light active layer is a periodic structure in which well layers and barrier layers grow alternately, the single-period thickness of the well layers of the green light active layer is 2.5 nm to 3 nm, and the single-period thickness of the barrier layers of the green light active layer is 7 nm to 11 nm.

[0017] Optionally, in the LED epitaxial structure, the thickness range of the second AlN nucleation layer is 100nm to 150nm; the thickness range of the second bottom buffer layer is 800nm ​​to 1200nm; the thickness range of the green light first-type semiconductor layer is 800nm ​​to 1200nm; the thickness of the second stress buffer layer is 200nm to 300nm; the thickness range of the green light second-type semiconductor layer is 128nm to 200nm.

[0018] Optionally, in the LED epitaxial structure, the red light epitaxial structure includes, from bottom to top, a third AlN nucleation layer, a third bottom buffer layer, a red light first-type semiconductor layer, a third stress buffer layer, a red light active layer and a red light second-type semiconductor layer.

[0019] Optionally, the red light active layer is a periodic structure in which well layers and barrier layers grow alternately, the single-period thickness of the well layers of the red light active layer is 4nm-5nm, and the single-period thickness of the barrier layers of the red light active layer is 11nm-15nm.

[0020] Optionally, in the LED epitaxial structure, the thickness range of the third AlN nucleation layer is 150nm~200nm; the thickness range of the third bottom buffer layer is 1200nm~2000nm; the thickness range of the red light first-type semiconductor layer is 1200nm~2000nm; the thickness range of the third stress buffer layer is 300nm~500nm; the thickness range of the red light second-type semiconductor layer is 200nm~270nm.

[0021] Optionally, in the LED epitaxial structure, the smaller the acute angle formed between the slope surface and the horizontal plane, the higher the In component content in the structural layer having the In component formed thereon.

[0022] Optionally, in the LED epitaxial structure, the substrate is a sapphire substrate, a silicon substrate, a silicon carbide substrate or a gallium nitride substrate.

[0023] Compared with the prior art, the technical solution of the utility model has the following beneficial effects:

[0024] The LED epitaxial structure provided by the utility model has a plurality of graphic structures formed on the substrate, each of which is composed of a horizontal plane, a first slope surface and a second slope surface, and the acute angles formed between the first slope surface and the second slope surface and the horizontal plane are different. The epitaxial structure can be formed on the horizontal plane, the first slope surface and the second slope surface at the same time through a single epitaxial process, and a blue light epitaxial structure is formed on the first slope surface, a green light epitaxial structure is formed on the second slope surface, and a red light epitaxial structure is formed on the horizontal plane. Since the epitaxial growth rates and element incorporation efficiencies on different slope surfaces and horizontal planes on the substrate are different, the utility model can use the slope surface and the horizontal plane to prepare an epitaxial structure that emits light of different wavelengths, that is, the LED epitaxial structure of the utility model can simultaneously realize the emission of blue light, green light and red light, and can reduce the integration process of the epitaxial structure, saving costs, which is of great significance for the integration of blue light, green light and red light. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1a It is a cross-sectional view of a substrate of an embodiment of the utility model;

[0026] Figure 1b This is a top view of a substrate of an embodiment of the utility model;

[0027] Figure 2 is a cross-sectional view of a substrate of another embodiment of the utility model;

[0028] Figure 3 It is a cross-sectional view of a substrate of another embodiment of the utility model;

[0029] Figure 4 This is a schematic structural diagram of an LED epitaxial structure of an embodiment of the utility model;

[0030] Figure 1a to Figure 4 middle:

[0031] 10-substrate, 101-horizontal plane, 102-first slope plane, 103-second slope plane, 11-AlN nucleation layer, 12-bottom buffer layer, 13-first type semiconductor layer, 14-stress buffer layer, 15-active region, 16-electron blocking layer, 17-second type current spreading layer, 18-second type ohmic contact layer. DETAILED DESCRIPTION

[0032] The LED epitaxial structure proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0033] See also Figures 1a to 4The LED epitaxial structure provided by the utility model is an epitaxial structure that emits three-color light, and specifically may include:

[0034] A substrate 10 having a plurality of graphic structures formed thereon, each of the graphic structures being composed of a horizontal plane 101, a first slope plane 102 and a second slope plane 103, and the acute angles formed between the first slope plane 102 and the second slope plane 103 and the horizontal plane 101 are different;

[0035] The epitaxial structure formed on the first slope surface 102, the second slope surface 103 and the horizontal surface 101, wherein the epitaxial structure on the first slope surface 102 is a blue light epitaxial structure, the epitaxial structure on the second slope surface 103 is a green light epitaxial structure, and the epitaxial structure on the horizontal surface 101 is a red light epitaxial structure.

[0036] In this embodiment, since the growth rates and element incorporation efficiencies of the epitaxial structures on different slope surfaces and horizontal surfaces are different, different epitaxial structures can be formed on the horizontal surface 101, the first slope surface 102, and the second slope surface 103 through a single epitaxial process. That is, the utility model can simultaneously realize the emission of blue light, green light, and red light, and can reduce the integration process and save costs, which is of great significance for the integration of blue light, green light, and red light three-color epitaxial structures.

[0037] In this embodiment, the blue light epitaxial structure includes, from bottom to top, a first AlN nucleation layer, a first bottom buffer layer, a blue light first-type semiconductor layer, a first stress buffer layer, a blue light active layer, and a blue light second-type semiconductor layer. The blue light second-type semiconductor layer may include a first electron blocking layer, a blue light second-type current spreading layer, and a blue light second-type ohmic contact layer stacked in sequence, but is not limited thereto.

[0038] The green epitaxial structure includes, from bottom to top, a second AlN nucleation layer, a second bottom buffer layer, a green first-type semiconductor layer, a second stress buffer layer, a green active layer, and a green second-type semiconductor layer. The green second-type semiconductor layer may include a second electron blocking layer, a green second-type current spreading layer, and a green second-type ohmic contact layer stacked in sequence, but is not limited thereto.

[0039] The red light epitaxial structure includes, from bottom to top, a third AlN nucleation layer, a third bottom buffer layer, a red light first-type semiconductor layer, a third stress buffer layer, a red light active layer, and a red light second-type semiconductor layer. The red light second-type semiconductor layer may include a third electron blocking layer, a red light second-type current spreading layer, and a red light second-type ohmic contact layer stacked in sequence, but is not limited thereto.

[0040] In this embodiment, the LED epitaxial structure is preferably a gallium nitride-based LED epitaxial structure.

[0041] The method for preparing the LED epitaxial structure may include the following steps:

[0042] Step S1: providing a substrate 10;

[0043] Step S2: etching the substrate 10 to form a plurality of graphic structures on the substrate 10, each of the graphic structures being composed of a horizontal plane 101, a first slope plane 102 and a second slope plane 103, and the acute angles formed between the first slope plane 102 and the second slope plane 103 and the horizontal plane 101 are different;

[0044] Step S3: forming an epitaxial structure on the substrate through a single epitaxial process, wherein the epitaxial structure formed on the first slope surface 102 is a blue light epitaxial structure, the epitaxial structure formed on the second slope surface 103 is a green light epitaxial structure, and the epitaxial structure formed on the horizontal surface 101 is a red light epitaxial structure.

[0045] The preparation process of the LED epitaxial structure in this embodiment can be any one of MOCVD (metal organic chemical vapor deposition) process, MBE (molecular beam epitaxy) process, HVPE (hydride vapor phase epitaxy) process, PECVD (plasma enhanced chemical vapor deposition process) and sputtering method, preferably MOCVD process.

[0046] Step S1 is performed to provide a substrate 10. In this embodiment, the substrate 10 is preferably a sapphire substrate, a silicon substrate, a silicon carbide substrate or a gallium nitride substrate, but is not limited thereto.

[0047] Step S2 is performed to etch the substrate 10 to form a plurality of graphic structures. The etching in this embodiment is preferably dry etching, but is not limited thereto. In this embodiment, each of the graphic structures is composed of a horizontal plane 101, a first slope surface 102, and a second slope surface 103, and the acute angle formed by the first slope surface 102 and the horizontal plane 101 is different from the acute angle formed by the second slope surface 103 and the horizontal plane 101.

[0048] The cross-sectional shape of each of the graphic structures in a direction perpendicular to the surface of the substrate 10 is preferably the same, and the cross-sectional shape of each of the graphic structures in a direction parallel to the surface of the substrate 10 is also preferably the same. Figure 1a , the cross section of the graphic structure in the direction perpendicular to the surface of the substrate 10 may be an isosceles trapezoid, that is, the three-dimensional shape of each of the graphic structures is a quadrangular prism, wherein the bottom surface of the quadrangular prism is an isosceles trapezoid; see Figure 1b, the cross section of the graphic structure in the direction parallel to the surface of the substrate 10 is preferably a rectangle (strip), and the multiple graphic structures are arranged in parallel, that is, the cross sections of the multiple graphic structures in the direction parallel to the surface of the substrate 10 are preferably parallelly arranged rectangles. In this embodiment, when the graphic structure is preferably an unequally shaped trapezoid, the spacing L1 between adjacent graphic structures is preferably in the range of 3μm to 5μm; the height range h1 of the graphic structure is preferably 7μm to 10μm, the acute angle formed between the first slope surface 102 and the horizontal plane 101 is preferably 60° to 75°, the acute angle formed between the second slope surface 103 and the horizontal plane 101 is preferably 30° to 45°, and the width W1 of the horizontal plane 101 is preferably in the range of 10μm to 20μm. Figure 1a The horizontal plane 101 of the graphic structure is plane D 11 ,and Figure 1a Plane D 12 It is the substrate between adjacent graphic structures. In the epitaxial process, the plane D 11 and plane D 12 The epitaxial structures grown on the surface are all red light epitaxial structures. 12 As an isolation region (i.e., a red epitaxial structure, a green epitaxial structure and a blue epitaxial structure formed on a graphic structure form a pixel unit or a light-emitting unit, and the adjacent units are isolated regions, and no epitaxial structure is required), the plane D 12 The red light epitaxial structure grown on it will be etched away in the subsequent steps.

[0049] In another embodiment, see Figure 2 The cross-section of the graphic structure in the direction perpendicular to the surface of the substrate 10 may also be an isosceles inverted trapezoid, that is, the three-dimensional shape of each of the graphic structures is a quadrangular prism-shaped groove, wherein the bottom surface of the quadrangular prism is an isosceles trapezoid; the cross-section of the graphic structure in the direction parallel to the surface of the substrate 10 is preferably a rectangle. Figure 2 The graphic structure and Figure 1a The parameters of the first slope surface 102, the second slope surface 103 and the horizontal plane 101 of the graphic structure are set the same, that is, the spacing L2 between adjacent graphic structures is preferably in the range of 3μm to 5μm; the height range h2 of the graphic structure is preferably 7μm to 10μm, the acute angle formed between the first slope surface 102 and the horizontal plane 101 is preferably 60° to 75°, the acute angle formed between the second slope surface 103 and the horizontal plane 101 is preferably 30° to 45°, and the width W2 of the horizontal plane 101 is preferably in the range of 10μm to 20μm. Figure 2 The horizontal plane 101 of the graphic structure is plane D 21 ,and Figure 2Plane D 22 It is the substrate between adjacent graphic structures. In the epitaxial process, the plane D 21 and plane D 22 The epitaxial structures grown on the surface are all red light epitaxial structures. 22 As an isolation area, plane D 22 The red light epitaxial structure grown on it will be etched away in the subsequent steps.

[0050] In yet another embodiment, see Figure 3 The cross-section of the graphic structure in the direction perpendicular to the surface of the substrate 10 can also be an isosceles triangle with an outer horizontal line, that is, the three-dimensional shape of each of the graphic structures is a triangular prism plus an adjacent partial plane, wherein the bottom surface of the triangular prism is an isosceles triangle, that is, the first slope surface 102 and the second slope surface 103 are the two sides of the isosceles triangle, and the horizontal plane 101 is the outer horizontal line, and the cross-section of the graphic structure in the direction parallel to the surface of the substrate 10 is preferably a rectangle. Figure 3 Graphic structure and Figure 1a The parameters of the first slope surface 102, the second slope surface 103 and the horizontal surface 101 of the graphic structure are set the same, that is, the interval L3 between adjacent graphic structures is preferably in the range of 3 μm to 5 μm; Figure 3 The height range h3 of the graphic structure is 7μm~10μm, the acute angle formed between the first slope surface 102 and the horizontal plane 101 is 60°~75°, the acute angle formed between the second slope surface 103 and the horizontal plane 101 is 30°~45°, and the width range W3 of the horizontal plane 101 is 10μm~20μm. Figure 3 The horizontal plane 101 of the graphic structure is plane D 31 ,and Figure 3 Plane D 32 It is the substrate between adjacent graphic structures. In the epitaxial process, the plane D 31 and plane D 32 The epitaxial structures grown on the surface are all red light epitaxial structures. 32 As an isolation area, plane D 32 The red light epitaxial structure grown on it will be etched away in the subsequent steps.

[0051] When the cross-section of the graphic structure in a direction perpendicular to the surface of the substrate 10 is an isosceles trapezoid, an isosceles inverted trapezoid, or an isosceles triangle with a horizontal line, the epitaxial growth space is large, and a smooth and flat plane can be obtained when the epitaxial process is completed.

[0052] Step S3 is executed to grow an epitaxial structure on the substrate 10. In this embodiment, since the growth rate of the epitaxial structure and the efficiency of element incorporation on different slope surfaces and horizontal surfaces are different, different epitaxial structures can be formed on the horizontal surface 101, the first slope surface 102 and the second slope surface 103 at the same time through a single epitaxial process. Only by adopting the above-mentioned design of the first slope surface 102, the second slope surface 103 and the horizontal surface 101 can a blue light epitaxial structure be formed on the first slope surface 102, a green light epitaxial structure be formed on the second slope surface 103, and a red light epitaxial structure be formed on the horizontal surface 101 through a single epitaxial process.

[0053] See also Figure 4 In this embodiment, the epitaxial structures on the first slope surface 102, the second slope surface 103 and the horizontal surface 101 may include, from bottom to top: an AlN nucleation layer 11, a bottom buffer layer 12, a first-type semiconductor layer 13, a stress buffer layer 14, an active layer 15 and a second-type semiconductor layer. The second-type semiconductor layer may include an electron blocking layer (EBL) 16, a second-type current spreading layer 17 and a second-type ohmic contact layer 18 stacked in sequence. In this embodiment, the first-type semiconductor layer and the second-type semiconductor layer have opposite polarities. For example, if the first-type semiconductor layer is an N-type semiconductor layer, the corresponding second-type semiconductor layer is a P-type semiconductor layer.

[0054] In this embodiment, the smaller the acute angle formed between the slope surface and the horizontal plane 101, the greater the epitaxial growth rate thereon, so the epitaxial growth rate of the horizontal plane 101 is greater than the epitaxial growth rate of the second slope surface 103, and the epitaxial growth rate of the second slope surface 103 is greater than the epitaxial growth rate of the first slope surface 102, and the difference in growth rate will cause the growth thickness to be different, that is, the thicknesses of the structural layers corresponding to the blue light epitaxial structure, the green light epitaxial structure and the red light epitaxial structure are different, and the smaller the acute angle formed between the slope surface and the horizontal plane, the greater the thickness of the structural layers formed thereon. In this embodiment, the smaller the acute angle formed between the slope surface and the horizontal plane 101, the greater the incorporation efficiency of the elements on it, so the incorporation efficiency of the elements on the horizontal plane 101 is greater than the incorporation efficiency of the elements on the second slope surface 103, and the incorporation efficiency of the elements on the second slope surface 103 is greater than the incorporation efficiency of the elements on the first slope surface 102, and the difference in the incorporation efficiency of the elements will cause the material composition to be different. In this embodiment, when epitaxially growing a structural layer of a material of two components, the content of the material component of the structural layer grown on the first slope surface 102, the second slope surface 103 and the horizontal plane 101 is the same, for example, the material component of the AlN nucleation layer grown on the first slope surface 102, the second slope surface 103 and the horizontal plane 101 is AlN, and the material component of the grown first-type semiconductor layer is GaN. When epitaxially growing a structural layer of materials having at least three components, the first slope surface 102, the second slope surface 103 and the horizontal surface 101 have different contents of the material components of the structural layer. For example, the smaller the acute angle formed between the slope surface and the horizontal surface 101, the higher the content of the In component in the structural layer having the In component formed thereon. For another example, the material of the well layer formed on the first slope surface 102 is In x Ga 1-x N, where x ranges from 0.15 to 0.2; the material of the well layer formed on the second slope surface 103 is In y Ga 1-y N, where y ranges from 0.2 to 0.25; the material of the well layer formed on the horizontal plane 101 is In z Ga 1-z N, where z ranges from 0.25 to 0.3.

[0055] In this embodiment, the method for preparing the epitaxial structure may include the following steps:

[0056] Step S31: growing an AlN nucleation layer 11 on the substrate 10;

[0057] Step S32: growing a bottom buffer layer 12 on the AlN nucleation layer 11;

[0058] Step S33: growing a first type semiconductor layer 13 on the bottom buffer layer 12;

[0059] Step S34: growing a stress buffer layer 14 on the first-type semiconductor layer 13;

[0060] Step S35: growing an active layer 15 on the stress buffer layer 14;

[0061] Step S36: growing an electron blocking layer 16 on the active layer 15;

[0062] Step S37: growing a second type current spreading layer 17 on the electron blocking layer 16;

[0063] Step S38 : growing a second-type ohmic contact layer 18 on the second-type current spreading layer 17 .

[0064] Step S31 is performed to grow an AlN nucleation layer 11 on the substrate 10, specifically including: growing a third AlN nucleation layer on the horizontal surface 101, growing a first AlN nucleation layer on the first slope surface 102, and growing a second AlN nucleation layer on the second slope surface 103. In this embodiment, the material of the first AlN nucleation layer may be AlN, and its thickness is preferably in the range of 20nm to 100nm; the material of the second AlN nucleation layer may be AlN, and its thickness is preferably in the range of 100nm to 150nm; the material of the third AlN nucleation layer may be AlN, and its thickness is preferably in the range of 150nm to 200nm.

[0065] Execute step S32 to grow a bottom buffer layer 12 on the AlN nucleation layer 11, specifically including: growing a third bottom buffer layer on the third AlN nucleation layer, growing a first bottom buffer layer on the first AlN nucleation layer, and growing a second bottom buffer layer on the second AlN nucleation layer. The material of the first bottom buffer layer in this embodiment may be GaN, AlN or AlGaN, etc., and its thickness range is preferably 500nm to 800nm; the material of the second bottom buffer layer may be GaN, AlN or AlGaN, etc., and its thickness range is preferably 800nm ​​to 1200nm; the material of the third bottom buffer layer may be GaN, AlN or AlGaN, etc., and its thickness range is preferably 1200nm to 2000nm.

[0066] Step S33 is executed to grow a first-type semiconductor layer 13 on the bottom buffer layer 12, specifically including: growing a red light first-type semiconductor layer on the third bottom buffer layer, growing a blue light first-type semiconductor layer on the first bottom buffer layer, and growing a green light first-type semiconductor layer on the second bottom buffer layer. In this embodiment, the material of the blue light first-type semiconductor layer can be GaN or AlGaN, etc., and its thickness range is preferably 500nm to 800nm; the material of the green light first-type semiconductor layer can be GaN or AlGaN, etc., and its thickness range is preferably 800nm ​​to 1200nm; the material of the red light first-type semiconductor layer can be GaN or AlGaN, etc., and its thickness range is preferably 1200nm to 2000nm.

[0067] Step S34 is performed to grow a stress buffer layer 14 on the first-type semiconductor layer 13, specifically including: growing a third stress buffer layer on the red light first-type semiconductor layer, growing a first stress buffer layer on the blue light first-type semiconductor layer, and growing a second stress buffer layer on the green light first-type semiconductor layer. The material of the first stress buffer layer of this embodiment can be at least one of GaN, AlGaN or InGaN, and its thickness range is preferably 100nm to 200nm; the material of the second stress buffer layer can be at least one of GaN, AlGaN or InGaN, and its thickness range is preferably 200nm to 300nm; the material of the third stress buffer layer can be at least one of GaN, AlGaN or InGaN, and its thickness range is preferably 300nm to 500nm.

[0068] Step S35 is performed to grow an active layer 15 on the stress buffer layer 14, specifically including: growing a red light active layer on the third stress buffer layer, growing a blue light active layer on the first stress buffer layer, and growing a green light active layer on the second stress buffer layer. The active layer 15 is a periodic structure formed by alternating growth of well layers and barrier layers, and the material of the well layer is preferably In f Ga 1-f N, where f is in the range of 0.15 to 0.3, and the material of the barrier layer is preferably GaN or Al g Ga 1-g N, wherein g is preferably in the range of 0.01 to 0.08. The blue light active layer of this embodiment is a periodic structure in which well layers and barrier layers grow alternately, the number of periods is preferably 3 to 20, the single period thickness of the blue light active layer is preferably 5 nm to 9.5 nm, and the material of the well layer of the blue light active layer can be In x Ga 1-xN, wherein the range of x is preferably 0.15 to 0.2, the single-period thickness of the well layer of the blue light active layer is preferably 2 nm to 2.5 nm, and the material of the barrier layer of the blue light active layer can be Al g1 Ga 1-g1 N, wherein the range of g1 is preferably 0.01 to 0.02, the single-period thickness of the barrier layer of the blue light active layer is preferably 3nm to 7nm; the green light active layer is a periodic structure in which the well layer and the barrier layer grow alternately, the number of periods is preferably 3 to 20, the single-period thickness of the green light active layer is preferably 9.5nm to 14nm, and the material of the well layer of the green light active layer is preferably In y Ga 1-y N, wherein y ranges from 0.2 to 0.25, the single-period thickness of the well layer of the green light active layer is preferably 2.5 nm to 3 nm, and the material of the barrier layer of the green light active layer can be Al g2 Ga 1-g2 N, wherein the range of g2 is preferably 0.02 to 0.05, the single-period thickness of the barrier layer of the green light active layer is preferably 7nm to 11nm; the red light active layer is a periodic structure in which the well layer and the barrier layer grow alternately, the number of periods is preferably 3 to 20, the single-period thickness of the red light active layer is preferably 15nm to 20nm, and the material of the well layer of the red light active layer is In z Ga 1-z N, wherein z ranges from 0.25 to 0.3, the single-period thickness of the well layer of the red light active layer is preferably 4 nm to 5 nm, and the material of the barrier layer of the red light active layer can be Al g3 Ga 1-g3 N, wherein the range of g3 is preferably 0.05 to 0.08, and the single-period thickness of the barrier layer of the red light active layer is preferably 11 nm to 15 nm.

[0069] The thickness and composition of the well layer of the active layer on each surface of this embodiment are different, so that different colors of light are emitted when electrons and holes are radiated and recombined. The light emitted by the active layer of the first slope surface 102 is blue light, the light emitted by the active layer of the second slope surface 103 is green light, and the light emitted by the active layer of the horizontal surface 101 is red light. That is, this embodiment can prepare an epitaxial structure that emits red, green and blue light.

[0070] Moreover, in this embodiment, when the emission wavelength of the well layer on the horizontal plane 103 is determined, the thickness and In composition of the well layer on the first slope surface 102 and the second slope surface can be adjusted by adjusting the inclination angles of the first slope surface 102 and the second slope surface 103 (that is, the acute angle formed between the first slope surface 102 and the horizontal plane 103 and the acute angle formed between the second slope surface 103 and the horizontal plane 103), thereby adjusting the emission wavelength of the first slope surface and the second slope surface, and adjusting the emission intensity of the three emission wavelengths, thereby adjusting the light color of the mixed light.

[0071] Step S36 is performed to grow an electron blocking layer 16 on the active layer 15, specifically including: growing a third electron blocking layer on the red light active layer, growing a first electron blocking layer on the blue light active layer, and growing a second electron blocking layer on the green light active layer. The first electron blocking layer of this embodiment is of P type, and its material can be Al v1 Ga 1-v1 N, wherein the range of v1 is preferably 0.1 to 0.15, the thickness of the first electron blocking layer is preferably in the range of 10 nm to 20 nm; the second electron blocking layer is P-type, and its material can be Al v2 Ga 1-v2 N, wherein v2 is preferably in the range of 0.15 to 0.2, the thickness of the second electron blocking layer is preferably in the range of 20 nm to 35 nm; the third electron blocking layer is of P type, and its material may be Al v3 Ga 1-v3 N, wherein the range of v3 is preferably 0.2 to 0.3, and the thickness of the third electron blocking layer is preferably in the range of 35 nm to 50 nm.

[0072] Step S37 is performed to grow a second-type current spreading layer 17 on the electron blocking layer 16, specifically including: growing a red light second-type current spreading layer on the third electron blocking layer, growing a blue light second-type current spreading layer on the first electron blocking layer, and growing a green light second-type current spreading layer on the second electron blocking layer. The material of the blue light second-type current spreading layer in this embodiment can be GaN or Al j1 Ga 1-j1 N, wherein the range of j1 is preferably 0.02 to 0.04, and the thickness range is preferably 20 nm to 100 nm; the material of the green light second-type current spreading layer can be GaN or Al j2 Ga 1-j2 N, wherein the range of j2 is preferably 0.04 to 0.08, and the thickness range is preferably 100 nm to 150 nm; the material of the red light second-type current spreading layer can be GaN or Al j3 Ga 1-j3N, wherein the range of j3 is preferably 0.08 to 0.1, and the thickness range is preferably 150 nm to 200 nm.

[0073] Step S38 is executed to grow a second-type ohmic contact layer 18 on the second-type current spreading layer 17, specifically including: growing a red light second-type ohmic contact layer on the red light second-type current spreading layer to obtain a red light epitaxial structure, growing a blue light second-type ohmic contact layer on the blue light second-type current spreading layer to obtain a blue light epitaxial structure, and growing a green light second-type ohmic contact layer on the green light second-type current spreading layer to obtain a green light epitaxial structure. In this embodiment, the material of the blue light second-type ohmic contact layer may be GaN or the like, and the thickness of the blue light second-type ohmic contact layer is preferably in the range of 3nm to 8nm; the material of the green light second-type ohmic contact layer may be GaN or the like, and the thickness of the green light second-type ohmic contact layer is preferably in the range of 8nm to 15nm; the material of the red light second-type ohmic contact layer may be GaN or the like, and the thickness of the red light second-type ohmic contact layer is preferably in the range of 15nm to 20nm. The first electron blocking layer, the blue light second type current spreading layer and the blue light second type ohmic contact layer of this embodiment constitute a blue light second type semiconductor layer, and the thickness range of the blue light second type semiconductor layer is preferably 33nm to 128nm; the second electron blocking layer, the green light second type current spreading layer and the green light second type ohmic contact layer constitute a green light second type semiconductor layer, and the thickness range of the green light second type semiconductor layer is preferably 128nm to 200nm; the third electron blocking layer, the red light second type current spreading layer and the red light second type ohmic contact layer constitute a red light second type semiconductor layer, and the thickness range of the red light second type semiconductor layer is preferably 200nm to 270nm.

[0074] In this embodiment, slope surfaces with different angles are formed on the substrate, and then a bottom buffer layer and a stress buffer layer are grown, so that a high-quality thin film with a clear interface can be obtained when the active layer is grown. In addition, in this embodiment, the growth rate and material composition on the slope surface can be adjusted by adjusting the inclination angles of different slope surfaces on the substrate, thereby obtaining active layers with different thicknesses and different compositions, and the luminous wavelength of the prepared epitaxial layer can be easily controlled.

[0075] Secondly, if slope surfaces of different angles are etched on the first-type semiconductor layer, the surface of the slope surface is rough and not smooth, and it is difficult to form an active layer with high crystal quality. In this embodiment, the slope surface is formed on the substrate to avoid the problem of poor crystal quality of the active layer, low radiation recombination efficiency or even inability to form effective recombination; if epitaxial structures are formed on different polarity planes, the manufacturing process is complicated and difficult to control. The polarization degrees of the epitaxial structures grown on different polarity planes are different, making it difficult to control the emission wavelength. In this embodiment, the slope surface is formed on the substrate, and active layers of different thicknesses and compositions are obtained by controlling the growth rate and composition. The manufacturing is simple and the emission wavelength is easy to control.

[0076] Moreover, the blue light epitaxial structure, green light epitaxial structure and red light epitaxial structure designed in this embodiment are all gallium nitride-based LED epitaxial structures, and this embodiment can complete the preparation of the blue light epitaxial structure, the green light epitaxial structure and the red light epitaxial structure in a one-time epitaxial process, reducing the integration process of the three-color epitaxial structure and saving costs at the same time, which is of great significance for the integration of the blue light, green light and red light three-color epitaxial structures.

[0077] In addition, it is understood that although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

[0078] It should also be understood that the utility model is not limited to the specific methods, compounds, materials, manufacturing techniques, usages and applications described herein, which can vary. It should also be understood that the terms described herein are only used to describe specific embodiments, rather than to limit the scope of the utility model. It must be noted that the singular forms "one", "a kind" and "the" used herein and in the appended claims include plural references unless the context clearly indicates the opposite meaning. Therefore, for example, a reference to "a step" or "a device" means a reference to one or more steps or devices, and may include secondary steps and secondary devices. All conjunctions used should be understood in the broadest sense. Therefore, the word "or" should be understood to have a logical "or" definition, rather than a logical "exclusive or" definition, unless the context clearly indicates the opposite meaning. The structure described here will be understood to also quote the functional equivalent of the structure. Language that can be interpreted as approximate should be understood that way unless the context clearly indicates the opposite meaning.

[0079] Moreover, for the convenience of description, spatially relative terms such as "on", "above", "above", "upper", etc. may be used in the present utility model to describe the relationship between one element or feature and another element or feature as shown in the figure. In addition to the orientations depicted in the accompanying drawings, spatially relative terms are intended to cover different orientations of the device in use or operation. The device can be oriented in other ways (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein can also be interpreted accordingly. Moreover, in the present utility model, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be noted that the technical solutions recorded in the embodiments of the present utility model can be arbitrarily combined without conflict.

Claims

1. An LED epitaxial structure, characterized in that: It is an epitaxial structure that emits three-color light, specifically including: A substrate having a plurality of graphic structures formed thereon, each of the graphic structures being composed of a horizontal plane, a first slope plane and a second slope plane, and the acute angles formed between the first slope plane and the second slope plane and the horizontal plane are different; The epitaxial structure formed on the first slope surface, the second slope surface and the horizontal surface, wherein the epitaxial structure on the first slope surface is a blue light epitaxial structure, the epitaxial structure on the second slope surface is a green light epitaxial structure, and the epitaxial structure on the horizontal surface is a red light epitaxial structure.

2. The LED epitaxial structure according to claim 1, characterized in that: The cross section of the graphic structure in a direction perpendicular to the substrate surface is an isosceles trapezoid, an isosceles inverted trapezoid, or an isosceles triangle with a horizontal line; the cross section of the graphic structure in a direction parallel to the substrate surface is a rectangle.

3. The LED epitaxial structure according to claim 1 or 2, characterized in that: The spacing between adjacent graphic structures ranges from 3μm to 5μm; the height of the graphic structure ranges from 7μm to 10μm, the acute angle formed between the first slope surface and the horizontal plane is 60° to 75°, the acute angle formed between the second slope surface and the horizontal plane is 30° to 45°, and the width of the horizontal plane ranges from 10μm to 20μm.

4. The LED epitaxial structure according to claim 1, characterized in that: The thicknesses of the structural layers corresponding to the blue epitaxial structure, the green epitaxial structure and the red epitaxial structure are different, and the smaller the acute angle formed between the slope surface and the horizontal plane, the greater the thickness of the structural layers formed thereon.

5. The LED epitaxial structure according to claim 1, characterized in that: The blue light epitaxial structure includes, from bottom to top, a first AlN nucleation layer, a first bottom buffer layer, a blue light first-type semiconductor layer, a first stress buffer layer, a blue light active layer and a blue light second-type semiconductor layer.

6. The LED epitaxial structure according to claim 5, characterized in that: The blue light active layer is a periodic structure of alternately grown well layers and barrier layers, the single period thickness of the well layers of the blue light active layer is 2nm-2.5nm, and the single period thickness of the barrier layers of the blue light active layer is 3nm-7nm.

7. The LED epitaxial structure according to claim 5, characterized in that: The thickness range of the first AlN nucleation layer is 20nm to 100nm; the thickness range of the first bottom buffer layer is 500nm to 800nm; the thickness range of the blue light first-type semiconductor layer is 500nm to 800nm; the thickness range of the first stress buffer layer is 100nm to 200nm; the thickness range of the blue light second-type semiconductor layer is 33nm to 128nm.

8. The LED epitaxial structure according to claim 1, characterized in that: The green light epitaxial structure includes, from bottom to top, a second AlN nucleation layer, a second bottom buffer layer, a green light first-type semiconductor layer, a second stress buffer layer, a green light active layer and a green light second-type semiconductor layer.

9. The LED epitaxial structure according to claim 8, characterized in that: The green light active layer is a periodic structure of alternately grown well layers and barrier layers, the single period thickness of the well layers of the green light active layer is 2.5nm-3nm, and the single period thickness of the barrier layers of the green light active layer is 7nm-11nm.

10. The LED epitaxial structure according to claim 8, characterized in that: The thickness of the second AlN nucleation layer ranges from 100nm to 150nm; the thickness of the second bottom buffer layer ranges from 800nm ​​to 1200nm; the thickness of the green light first-type semiconductor layer ranges from 800nm ​​to 1200nm; the thickness of the second stress buffer layer ranges from 200nm to 300nm; the thickness of the green light second-type semiconductor layer ranges from 128nm to 200nm.

11. The LED epitaxial structure according to claim 1, characterized in that: The red light epitaxial structure includes, from bottom to top, a third AlN nucleation layer, a third bottom buffer layer, a red light first-type semiconductor layer, a third stress buffer layer, a red light active layer and a red light second-type semiconductor layer.

12. The LED epitaxial structure according to claim 11, characterized in that: The red light active layer is a periodic structure of alternately grown well layers and barrier layers, the single-period thickness of the well layers of the red light active layer is 4nm-5nm, and the single-period thickness of the barrier layers of the red light active layer is 11nm-15nm.

13. The LED epitaxial structure according to claim 11, characterized in that: The thickness range of the third AlN nucleation layer is 150nm-200nm; the thickness range of the third bottom buffer layer is 1200nm-2000nm; the thickness range of the red light first-type semiconductor layer is 1200nm-2000nm; the thickness range of the third stress buffer layer is 300nm-500nm; the thickness range of the red light second-type semiconductor layer is 200nm-270nm.

14. The LED epitaxial structure according to claim 1, characterized in that: The smaller the acute angle formed between the slope surface and the horizontal plane is, the higher the In component content in the structure layer having the In component formed thereon is.

15. The LED epitaxial structure according to claim 1, characterized in that: The substrate is a sapphire substrate, a silicon substrate, a silicon carbide substrate or a gallium nitride substrate.

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