A light-emitting diode wafer and its fabrication method

Abstract

This invention discloses a light-emitting diode (LED) wafer and its fabrication method. In the LED wafer fabrication method of this invention, a first metal thin layer is deposited on the P-type semiconductor layer, and the first metal thin layer is heat-treated to form a first metal particle layer. Then, a 2,9-dihexylnaphthalene[2,3-b]naphthalene[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer is grown on the first metal particle layer using a solution containing 2,9-dihexylnaphthalene[2,3-b]naphthalene[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer. Following this, a silver nanowire conductive layer and a transparent conductive layer are formed. The arrangement of these layers can greatly improve the efficiency of hole injection from the transparent conductive layer into the P-type semiconductor layer, thereby improving the light-emitting performance of the LED wafer.

Description

Technical Field

[0001] This invention relates to the field of semiconductor light-emitting technology, specifically to a light-emitting diode wafer and its fabrication method. Background Technology

[0002] Gallium nitride (GaN)-based light-emitting diode (LED) wafers are core materials in modern semiconductor lighting and display technologies, becoming the mainstream choice in these fields due to their high efficiency, long lifespan, and environmental friendliness. Traditional LED wafers mainly consist of a growth substrate, and on this substrate, sequentially grown layers including a buffer layer, a silicon-doped n-type GaN layer, alternating InGaN / GaN multi-quantum-well active layers, a magnesium-doped p-type GaN layer, and a transparent conductive layer. In the LED chip formation process, the wafer undergoes photolithography and etching to define the device structure of a single LED chip. Then, metal electrodes and passivation layers are deposited via electron beam evaporation or sputtering to prevent electrode oxidation and leakage. Finally, the wafer is laser-cut or diamond-bladed, and qualified LED chips are sorted. Improving the contact performance between the p-type GaN layer and the transparent conductive layer, increasing hole injection efficiency, and thus improving the light extraction efficiency and lifespan of the LED chip, has attracted widespread attention. Summary of the Invention

[0003] To address the aforementioned problems in the prior art, this application provides a light-emitting diode wafer and a method for fabricating the same.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] An embodiment of this application provides a method for fabricating a light-emitting diode (LED) wafer, the method comprising the following steps:

[0006] Provide growth substrate.

[0007] A buffer layer, an N-type semiconductor layer, a quantum well light-emitting layer, and a P-type semiconductor layer are epitaxially grown on the growth substrate. The buffer layer includes a stacked aluminum oxynitride layer, a first aluminum nitride layer, and a second aluminum nitride layer. The second aluminum nitride layer includes a lower surface in contact with the first aluminum nitride layer and an upper surface away from the first aluminum nitride layer. The gallium doping concentration in the second aluminum nitride layer gradually increases from the lower surface to the upper surface.

[0008] The P-type semiconductor layer is planarized, and then a first metal thin layer with a thickness of 5-20 nanometers is deposited on the P-type semiconductor layer.

[0009] The first metal thin layer is then heat-treated to form a first metal particle layer.

[0010] A solution containing 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules was prepared, and a layer of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules was grown on the first metal particle layer using the solution containing 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules.

[0011] A silver nanowire conductive layer is formed on the organic small molecule layer of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene.

[0012] Next, a transparent conductive layer is deposited on the silver nanowire conductive layer.

[0013] In a preferred embodiment, the material of the first metal thin layer is one of gold, silver or copper, the heat treatment temperature for the first metal thin layer is 200-500℃, the heat treatment time is 10-50 minutes, and the particle size of the metal particles in the first metal particle layer is 20-100 nanometers.

[0014] In a preferred embodiment, the concentration of the organic small molecules in the solution containing 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene is 0.3-0.7 mg / mL.

[0015] As a preferred embodiment, the 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer was grown by solution shearing.

[0016] As a preferred embodiment, the specific process of the solution shearing method is as follows: the growth substrate forming the first metal particle layer is placed on a first heating plate, and a solution containing small organic molecules of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene is injected into the gap between the growth substrate and the second heating plate. The heating temperature of the first heating plate and the second heating plate is controlled at 65-75°C, and the moving speed of the second heating plate is controlled at 4-6 μm / s.

[0017] In a preferred embodiment, the distance between the first heating plate and the growth substrate is set to 50-70 micrometers, the angle between the first heating plate and the horizontal plane is 20-25°, and the plane on which the growth substrate is located is parallel to the horizontal plane.

[0018] In a preferred embodiment, the silver nanowire conductive layer is formed by a spraying process.

[0019] In a preferred embodiment, the silver nanowire conductive layer is formed by spraying a suspension containing silver nanowires, wherein the concentration of silver nanowires in the suspension is 30-60 mg / mL.

[0020] The present invention also proposes a light-emitting diode wafer, wherein the light-emitting diode wafer is formed by the above-described method for preparing a light-emitting diode wafer. The light-emitting diode wafer includes a buffer layer, an N-type semiconductor layer, a quantum well light-emitting layer, a P-type semiconductor layer, a first metal particle layer, a 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer, a silver nanowire conductive layer, and a transparent conductive layer. The buffer layer includes an aluminum oxynitride layer, a first aluminum nitride layer, and a second aluminum nitride layer, wherein the second aluminum nitride layer includes a lower surface in contact with the first aluminum nitride layer and an upper surface away from the first aluminum nitride layer. From the lower surface to the upper surface, the gallium doping concentration in the second aluminum nitride layer gradually increases.

[0021] Compared with the prior art, the light-emitting diode wafer and its fabrication method of the present invention have the following beneficial effects:

[0022] In the method for fabricating a light-emitting diode wafer of the present invention, a first metal thin layer is deposited on the P-type semiconductor layer, and the first metal thin layer is heat-treated to form a first metal particle layer. Then, a 2,9-dihexylnaphthalene[2,3-b]naphthalene[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer is grown on the first metal particle layer using a solution containing 2,9-dihexylnaphthalene[2,3-b]naphthalene[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer. Following this, a silver nanowire conductive layer and a transparent conductive layer are formed. The arrangement of these layers can greatly improve the efficiency of hole injection from the transparent conductive layer to the P-type semiconductor layer, thereby improving the light-emitting performance of the light-emitting diode wafer. The present invention improves the light-emitting performance of the light-emitting diode wafer by depositing a first metal thin layer on the P-type semiconductor layer and heat-treating the first metal thin layer. The introduction of the 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer into the fabrication process of light-emitting diode wafers revealed that the presence of this small molecule layer significantly improved the electrical contact characteristics between the P-type semiconductor layer and the transparent conductive layer. By optimizing the fabrication process parameters of the 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer, it was made to consist of discontinuous nanosheets. Consequently, during the subsequent formation of the silver nanowire conductive layer, the silver nanowires connected the nanosheets and partially made direct contact with the P-type semiconductor layer 500, further improving the contact performance between the P-type semiconductor layer 500 and the transparent conductive layer. During the deposition of the transparent conductive layer, part of the transparent conductive layer was embedded in the gaps between adjacent silver nanowires, thereby forming a bulk heterostructure of organic small molecules, silver nanowires, and transparent conductive materials, which greatly improved the hole injection efficiency. In addition, by optimizing the process parameters of the fabrication process of the 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer, it was found that the presence of this small molecule layer significantly improved the electrical contact characteristics between the P-type semiconductor layer and the transparent conductive layer. The structure of the buffer layer includes a stacked aluminum oxynitride layer, a first aluminum nitride layer, and a second aluminum nitride layer. The second aluminum nitride layer includes a lower surface in contact with the first aluminum nitride layer and an upper surface away from the first aluminum nitride layer. From the lower surface to the upper surface, the gallium doping concentration in the second aluminum nitride layer gradually increases. Through the above configuration, the lattice mismatch between the growth substrate and the P-type semiconductor layer is effectively reduced, the crystal quality of the P-type semiconductor layer is improved, and the crystal quality of the quantum well light-emitting layer is improved, thereby improving the luminous efficiency of the light-emitting diode wafer. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1This is a schematic diagram of the structure of the buffer layer epitaxially grown on the growth substrate in this application.

[0025] Figure 2 This is a schematic diagram of the structure in this application in which an N-type semiconductor layer, a quantum well light-emitting layer, and a P-type semiconductor layer are sequentially grown on a buffer layer.

[0026] Figure 3 This is a schematic diagram of the structure in which the first metal particle layer is formed in this application.

[0027] Figure 4 This is a schematic diagram of the structure of the organic small molecule layer of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene grown in this application.

[0028] Figure 5 This is a schematic diagram of the structure in this application that forms the silver nanowire conductive layer and the transparent conductive layer.

[0029] Explanation of reference numerals in the attached figures:

[0030] 100. Growth substrate; 201. Aluminum oxynitride layer; 202. First aluminum nitride layer; 203. Second aluminum nitride layer; 300. N-type semiconductor layer; 400. Quantum well light-emitting layer; 500. P-type semiconductor layer; 600. First metal particle layer; 700. 2,9-Dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer; 800. Silver nanowire conductive layer; 900. Transparent conductive layer. Detailed Implementation

[0031] The following detailed description of the embodiments of this application, in conjunction with the accompanying drawings, will provide a thorough understanding of how this application uses technical means to solve technical problems and achieve corresponding technical effects, enabling its implementation. The embodiments of this application and the various features within them can be combined with each other without conflict, and the resulting technical solutions are all within the protection scope of this application. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0032] It should be understood that although the terms "first," "second," "third," etc., may be used to describe various elements, components, areas, layers, and / or parts, these elements, components, areas, layers, and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or part from another element, component, area, layer, or part. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or part discussed below may be referred to as the second element, component, area, layer, or part.

[0033] It should be understood that spatial relation terms such as "above," "located above," "below," "located below," etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as "below other elements" will be oriented "above" other elements or features. Therefore, the exemplary terms "below" and "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0035] Embodiments of this application are described herein with reference to cross-sectional views illustrating ideal embodiments (and intermediate structures). Thus, variations in the shape shown can be anticipated due to, for example, fabrication techniques and / or tolerances. Therefore, embodiments of this application should not be limited to the specific shape of the region shown herein, but should include shape deviations due to, for example, fabrication processes.

[0036] To fully understand this application, detailed structures and steps will be presented in the following description to illustrate the technical solutions proposed in this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0037] An embodiment of this application provides a method for fabricating a light-emitting diode (LED) wafer, the method comprising the following steps:

[0038] like Figure 1 As shown, a growth substrate 100 is provided. The growth substrate 100 can be a sapphire substrate, a silicon substrate or a silicon carbide substrate. In a specific embodiment of the present invention, the growth substrate 100 is a sapphire substrate.

[0039] like Figure 1As shown, a buffer layer is epitaxially grown on the growth substrate 100. The buffer layer includes a stacked aluminum oxynitride layer 201, a first aluminum nitride layer 202, and a second aluminum nitride layer 203. The second aluminum nitride layer 203 includes a lower surface in contact with the first aluminum nitride layer 202 and an upper surface away from the first aluminum nitride layer 202. From the lower surface to the upper surface, the gallium doping concentration in the second aluminum nitride layer 203 gradually increases.

[0040] In a specific embodiment, an aluminum oxynitride layer 201 is formed by magnetron sputtering. The specific conditions of the magnetron sputtering process are as follows: pure aluminum palladium material is selected, inert argon gas is introduced as the sputtering gas, and nitrogen and oxygen are introduced as nitrogen source and oxygen source, respectively. The volume ratio of nitrogen to oxygen is adjusted to 1:1 to 5:1, the magnetron sputtering frequency is adjusted to 500-2000W, the magnetron sputtering temperature is adjusted to 200-500℃, and the gas pressure in the chamber during sputtering is 0.1-0.5Pa, so as to grow an aluminum oxynitride layer 201 with a thickness of 10-40 nanometers. More specifically, the thickness of the aluminum oxynitride layer 201 is 10 nanometers, 15 nanometers, 20 nanometers, 25 nanometers, 30 nanometers, 35 nanometers, and 40 nanometers.

[0041] In a specific embodiment, an aluminum nitride layer 202 is formed by magnetron sputtering. The specific conditions of the magnetron sputtering process are as follows: pure aluminum palladium material is selected, inert argon gas is introduced as the sputtering gas, and nitrogen gas is introduced as the nitrogen source and oxygen source. The magnetron sputtering frequency is adjusted to 500-2000W, the magnetron sputtering temperature is adjusted to 200-500℃, and the gas pressure in the chamber during sputtering is 0.1-0.5Pa, so as to grow an aluminum nitride layer 202 with a thickness of 30-150 nanometers. More specifically, the thickness of the aluminum nitride layer 202 is 30 nanometers, 50 nanometers, 70 nanometers, 90 nanometers, 110 nanometers, 130 nanometers, and 150 nanometers.

[0042] In a specific embodiment, a second aluminum nitride layer 203 is grown using metal-organic chemical vapor deposition (MOCVD). Trimethylaluminum is used as the aluminum source, ammonia as the nitrogen source, and trimethylgallium as the gallium source. The growth temperature is 900-1200℃, and the gas pressure in the reaction chamber is 10-200 Torr. The flow rates of the aluminum, nitrogen, and gallium sources are adjusted, with the molar flow rate ratio of nitrogen (ammonia) to aluminum (trimethylaluminum) being 1500-3000 and the molar flow rate ratio of trimethylgallium to trimethylaluminum being 0.01-0.2. By adjusting these growth processes, a gallium-doped aluminum nitride layer is formed. The gallium doping concentration in the second aluminum nitride layer 203 varies from (1×10¹⁰) in the direction from the lower surface to the upper surface. 6 cm⁻³-5×10¹ 6 (cm⁻³) gradually increases to (2×10)19 cm⁻³-7×10 19 (cm⁻³), to grow a second aluminum nitride layer 203 with a thickness of 20-100 nanometers, more specifically, the thickness of the second aluminum nitride layer 203 is 20 nanometers, 35 nanometers, 50 nanometers, 65 nanometers, 80 nanometers, 90 nanometers and 100 nanometers.

[0043] like Figure 2 As shown, an N-type semiconductor layer 300, a quantum well light-emitting layer 400, and a P-type semiconductor layer 500 are sequentially grown on the buffer layer.

[0044] In a specific embodiment, the N-type semiconductor layer 300 may be an N-type gallium nitride layer or an N-type aluminum gallium nitride layer, the P-type semiconductor layer 500 may be a P-type gallium nitride layer or a P-type aluminum gallium nitride layer, and the quantum well light-emitting layer 400 may be an alternating stack of InGaN quantum well layers and GaN quantum barrier layers or an alternating stack of AlGaN quantum well layers and AlGaN quantum barrier layers. The N-type semiconductor layer 300, the quantum well light-emitting layer 400, and the P-type semiconductor layer 500 are formed by metal-organic chemical vapor deposition.

[0045] like Figure 3 As shown, the P-type semiconductor layer 500 is planarized, and then a first metal thin layer with a thickness of 5-20 nanometers is deposited on the P-type semiconductor layer 500. The first metal thin layer is then heat-treated to form a first metal particle layer 600.

[0046] In a specific embodiment, the P-type semiconductor layer is planarized using a chemical mechanical polishing process, and then a first metal thin layer is deposited using a physical vapor deposition process, specifically a thermal evaporation process, a magnetron sputtering process, or an electron beam evaporation process. The material of the first metal thin layer is one of gold, silver, or copper, specifically a gold thin layer or a silver thin layer. The thickness of the first metal thin layer is specifically 5 nanometers, 7 nanometers, 9 nanometers, 11 nanometers, 14 nanometers, 16 nanometers, 18 nanometers, or 20 nanometers.

[0047] In a specific embodiment, the heat treatment temperature for the first metal thin layer is 200-500°C, the heat treatment time is 10-50 minutes, and the particle size of the metal particles in the first metal particle layer is 20-100 nanometers.

[0048] In a more specific embodiment, the heat treatment temperature is specifically 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, or 500°C, and the heat treatment time is specifically 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, or 50 minutes, thereby making the particle size range of the metal particles in the first metal particle layer 600 20-30 nanometers, 30-40 nanometers, 40-50 nanometers, 50-60 nanometers, 60-70 nanometers, 70-80 nanometers, 80-90 nanometers, or 90-100 nanometers.

[0049] Prepare a solution containing small organic molecules of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene.

[0050] In a specific embodiment, a solution containing small organic molecules of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene is prepared using one or more solvents selected from toluene, xylene, chlorobenzene, o-dichlorobenzene, and N,N-dimethylformamide. The concentration of the organic small molecules in the solution of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene is 0.3-0.7 mg / mL, more specifically 0.3 mg / mL, 0.34 mg / mL, 0.38 mg / mL, 0.4 mg / mL, 0.44 mg / mL, 0.48 mg / mL, 0.52 mg / mL, 0.56 mg / mL, 0.6 mg / mL, 0.65 mg / mL or 0.7 mg / mL, that is, to prepare an unsaturated or supersaturated solution of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules.

[0051] like Figure 4 As shown, a layer 700 of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules is grown on the first metal particle layer 600 using a solution containing 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules.

[0052] In a specific embodiment, the 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer 700 is grown by solution shearing.

[0053] In a specific embodiment, the specific process of the solution shearing method is as follows: the growth substrate 100 forming the first metal particle layer 600 is placed on a first heating plate (not shown), and a solution containing small organic molecules of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene is injected into the gap between the growth substrate 100 and the second heating plate (not shown). The heating temperature of the first heating plate and the second heating plate is controlled at 65-75°C, the moving speed of the second heating plate is controlled at 4-6 μm / s, the distance between the first heating plate and the growth substrate 100 is set to 50-70 micrometers, the angle between the first heating plate and the horizontal plane is 20-25°, and the plane on which the growth substrate is located is parallel to the horizontal plane.

[0054] In a more specific embodiment, by controlling the heating temperature of the first heating plate and the second heating plate to 65°C, 68°C, 70°C, 72°C, or 75°C, controlling the moving speed of the second heating plate to 4μm / s, 4.5μm / s, 5μm / s, 5.5μm / s, or 6μm / s, and controlling the distance between the first heating plate and the growth substrate 100 to 50μm, 55μm, 60μm, 65μm, or 70μm, and the angle between the first heating plate and the horizontal plane to 20-22° or 22-25°, a 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer 600 is formed. The thiophene[3,2-d]thiophene organic small molecule layer 700 is composed of discontinuous nanosheets. When the silver nanowire conductive layer is subsequently formed, the silver nanowires connect the nanosheets and partially contact the P-type semiconductor layer 500 directly, further improving the contact performance between the P-type semiconductor layer 500 and the transparent conductive layer.

[0055] like Figure 5 As shown, a silver nanowire conductive layer 800 is formed on the 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer 700.

[0056] In a specific embodiment, the silver nanowire conductive layer 800 is formed by a spraying process. Specifically, the silver nanowire conductive layer 800 is formed by spraying a suspension containing silver nanowires, wherein the concentration of silver nanowires in the suspension is 30-60 mg / mL.

[0057] In a more specific embodiment, the concentration of silver nanowires in the suspension containing silver nanowires is adjusted to 30 mg / mL, 35 mg / mL, 40 mg / mL, 45 mg / mL, 50 mg / mL, 55 mg / mL, or 60 mg / mL, and then the silver nanowire conductive layer 800 is formed by multiple sprayings, specifically 5-10 times, to form a silver nanowire conductive layer 800 of suitable thickness.

[0058] Next, a transparent conductive layer 900 is deposited on the silver nanowire conductive layer 800. In a specific embodiment, ITO or AZO is formed as the transparent conductive layer 900 by low-temperature deposition technology. More specifically, it is formed by any suitable process such as magnetron sputtering or electron beam evaporation, and the deposition temperature is not higher than 300°C. After deposition, a low-temperature annealing treatment is performed, and the annealing temperature is also not higher than 300°C.

[0059] like Figure 5 As shown, the present invention also proposes a light-emitting diode wafer, which is formed by the above-described method for preparing a light-emitting diode wafer. The light-emitting diode wafer includes a buffer layer, an N-type semiconductor layer 300, a quantum well light-emitting layer 400, a P-type semiconductor layer 500, a first metal particle layer 600, a 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer 700, a silver nanowire conductive layer 800, and a transparent conductive layer 900. The buffer layer includes an aluminum oxynitride layer 201, a first aluminum nitride layer 202, and a second aluminum nitride layer 203, which are stacked together. The second aluminum nitride layer 203 includes a lower surface in contact with the first aluminum nitride layer 202 and an upper surface away from the first aluminum nitride layer 202. The gallium doping concentration in the second aluminum nitride layer 203 gradually increases from the lower surface to the upper surface.

[0060] An embodiment of this application provides a method for fabricating a light-emitting diode (LED) wafer, the method comprising the following steps:

[0061] Provide growth substrate.

[0062] A buffer layer, an N-type semiconductor layer, a quantum well light-emitting layer, and a P-type semiconductor layer are epitaxially grown on the growth substrate. The buffer layer includes a stacked aluminum oxynitride layer, a first aluminum nitride layer, and a second aluminum nitride layer. The second aluminum nitride layer includes a lower surface in contact with the first aluminum nitride layer and an upper surface away from the first aluminum nitride layer. The gallium doping concentration in the second aluminum nitride layer gradually increases from the lower surface to the upper surface.

[0063] The P-type semiconductor layer is planarized, and then a first metal thin layer with a thickness of 5-20 nanometers is deposited on the P-type semiconductor layer.

[0064] The first metal thin layer is then heat-treated to form a first metal particle layer.

[0065] A solution containing 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules was prepared, and a layer of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules was grown on the first metal particle layer using the solution containing 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules.

[0066] A silver nanowire conductive layer is formed on the organic small molecule layer of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene.

[0067] Next, a transparent conductive layer is deposited on the silver nanowire conductive layer.

[0068] Furthermore, the material of the first metal thin layer is one of gold, silver or copper, the heat treatment temperature for the first metal thin layer is 200-500℃, the heat treatment time is 10-50 minutes, and the particle size of the metal particles in the first metal particle layer is 20-100 nanometers.

[0069] Furthermore, the concentration of the organic small molecules in the solution containing 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules is 0.3-0.7 mg / mL.

[0070] Furthermore, the 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer was grown by solution shearing.

[0071] Furthermore, the specific process of the solution shearing method is as follows: the growth substrate forming the first metal particle layer is placed on a first heating plate, and a solution containing small organic molecules of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene is injected into the gap between the growth substrate and the second heating plate. The heating temperature of the first heating plate and the second heating plate is controlled at 65-75°C, and the moving speed of the second heating plate is controlled at 4-6 μm / s.

[0072] Furthermore, the distance between the first heating plate and the growth substrate is set to 50-70 micrometers, the angle between the first heating plate and the horizontal plane is 20-25°, and the plane on which the growth substrate is located is parallel to the horizontal plane.

[0073] Furthermore, the silver nanowire conductive layer is formed through a spraying process.

[0074] Furthermore, the silver nanowire conductive layer is formed by spraying a suspension containing silver nanowires, wherein the concentration of silver nanowires in the suspension is 30-60 mg / mL.

[0075] The present invention also proposes a light-emitting diode wafer, wherein the light-emitting diode wafer is formed by the above-described method for preparing a light-emitting diode wafer. The light-emitting diode wafer includes a buffer layer, an N-type semiconductor layer, a quantum well light-emitting layer, a P-type semiconductor layer, a first metal particle layer, a 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer, a silver nanowire conductive layer, and a transparent conductive layer. The buffer layer includes an aluminum oxynitride layer, a first aluminum nitride layer, and a second aluminum nitride layer, wherein the second aluminum nitride layer includes a lower surface in contact with the first aluminum nitride layer and an upper surface away from the first aluminum nitride layer. From the lower surface to the upper surface, the gallium doping concentration in the second aluminum nitride layer gradually increases.

[0076] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for fabricating a light-emitting diode wafer, characterized in that: The method for fabricating the light-emitting diode wafer includes the following steps: Provide growth substrate; A buffer layer, an N-type semiconductor layer, a quantum well light-emitting layer, and a P-type semiconductor layer are epitaxially grown on the growth substrate. The buffer layer includes a stacked aluminum oxynitride layer, a first aluminum nitride layer, and a second aluminum nitride layer. The second aluminum nitride layer includes a lower surface in contact with the first aluminum nitride layer and an upper surface away from the first aluminum nitride layer. The gallium doping concentration in the second aluminum nitride layer gradually increases from the lower surface to the upper surface. The P-type semiconductor layer is planarized, and then a first metal thin layer is deposited on the P-type semiconductor layer, the thickness of the first metal thin layer being 5-20 nanometers. The first metal thin layer is then heat-treated to form a first metal particle layer; A solution containing 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules was prepared, and a layer of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules was grown on the first metal particle layer using the solution containing 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecules; A silver nanowire conductive layer is formed on the organic small molecule layer of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene; Next, a transparent conductive layer is deposited on the silver nanowire conductive layer.

2. The method for fabricating a light-emitting diode wafer according to claim 1, characterized in that: The first metal thin layer is made of gold, silver or copper, the heat treatment temperature for the first metal thin layer is 200-500℃, the heat treatment time is 10-50 minutes, and the particle size of the metal particles in the first metal particle layer is 20-100 nanometers.

3. The method for fabricating a light-emitting diode wafer according to claim 1, characterized in that: The concentration of the organic small molecules in the solution containing 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene is 0.3-0.7 mg / mL.

4. The method for fabricating a light-emitting diode wafer according to claim 1, characterized in that: The 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer was grown by solution shearing.

5. The method for fabricating a light-emitting diode wafer according to claim 4, characterized in that: The specific process of the solution shearing method is as follows: the growth substrate forming the first metal particle layer is placed on the first heating plate, and a solution containing small organic molecules of 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene is injected into the gap between the growth substrate and the second heating plate. The heating temperature of the first heating plate and the second heating plate is controlled at 65-75°C, and the moving speed of the second heating plate is controlled at 4-6 μm / s.

6. The method for fabricating a light-emitting diode wafer according to claim 5, characterized in that: The distance between the first heating plate and the growth substrate is set to 50-70 micrometers, the angle between the first heating plate and the horizontal plane is 20-25°, and the plane on which the growth substrate is located is parallel to the horizontal plane.

7. The method for fabricating a light-emitting diode wafer according to claim 1, characterized in that: The silver nanowire conductive layer is formed by a spraying process.

8. The method for fabricating a light-emitting diode wafer according to claim 7, characterized in that: The silver nanowire conductive layer is formed by spraying a suspension containing silver nanowires, wherein the concentration of silver nanowires in the suspension is 30-60 mg / mL.

9. A light-emitting diode wafer, characterized in that, The light-emitting diode wafer is fabricated using the method for fabricating a light-emitting diode wafer according to any one of claims 1-8. The light-emitting diode wafer includes a buffer layer, an N-type semiconductor layer, a quantum well light-emitting layer, a P-type semiconductor layer, a first metal particle layer, a 2,9-dihexylnaphthalene[2,3-b]naphtho[2',3':4,5]thiophene[3,2-d]thiophene organic small molecule layer, a silver nanowire conductive layer, and a transparent conductive layer. The buffer layer includes an aluminum oxynitride layer, a first aluminum nitride layer, and a second aluminum nitride layer, which are stacked together. The second aluminum nitride layer includes a lower surface in contact with the first aluminum nitride layer and an upper surface away from the first aluminum nitride layer. The gallium doping concentration in the second aluminum nitride layer gradually increases from the lower surface to the upper surface.

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