Ultraviolet LED epitaxial wafer and preparation method thereof, LED chip and light-emitting device

Abstract

The invention provides an ultraviolet LED epitaxial wafer and a preparation method thereof, an LED chip and a light-emitting device, and relates to the technical field of electronic components, the ultraviolet LED epitaxial wafer comprises a substrate, and an N-type layer, a multi-quantum well layer and a P-type layer which are stacked on the substrate in sequence; the multi-quantum well layer comprises a modified graphene layer, a ZnO quantum well layer and a ZnO quantum barrier layer; the modified graphene layer is a graphene layer subjected to plasma treatment, gas for plasma treatment is oxygen, and the problem that in the prior art, due to the fact that many defects and impurity energy levels exist in a ZnO material, the radiation luminous efficiency is affected can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic components, and in particular to an ultraviolet LED epitaxial wafer and a preparation method thereof, an LED chip, and a light-emitting device. Background Art

[0002] In recent years, the growing demand for high-brightness, miniaturized, energy-saving, and environmentally friendly LED chips has demonstrated tremendous potential in applications such as display lighting. Among LED chip construction materials, blue-violet LED chips, represented by GaN materials, are relatively mature and widely used. However, disadvantages such as high production costs and complex fabrication processes have limited further development in device manufacturing. With the rapid development of the semiconductor industry, zinc oxide (ZnO), another representative material for third-generation semiconductors, is considered an ideal material for constructing ultraviolet light-emitting diodes / laser diodes.

[0003] However, when ZnO material is used as the main material of the multi-quantum well layer, there are many defects and impurity energy levels in the ZnO material. These energy levels will capture electrons and holes, making them unable to effectively recombine and emit light in the quantum well. Instead, they consume energy through non-radiative recombination, such as releasing it in the form of heat energy, thereby reducing the luminescence efficiency. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a UV LED epitaxial wafer and its preparation method, LED chip, and light-emitting device, aiming to solve the problem in the existing technology that the radiation luminescence efficiency is affected by the presence of many defects and impurity energy levels in the ZnO material.

[0005] A first aspect of the present invention is to provide an ultraviolet LED epitaxial wafer, the ultraviolet LED epitaxial wafer comprising: A substrate, and an N-type layer, a multi-quantum well layer, and a P-type layer sequentially stacked on the substrate; The multi-quantum well layer includes a modified graphene layer, a ZnO quantum well layer, and a ZnO quantum barrier layer; The modified graphene layer is a graphene layer that has been treated with plasma, and the gas used for the plasma treatment is oxygen.

[0006] Compared with the existing technology, the beneficial effects of the present invention are: through the ultraviolet LED epitaxial wafer provided by the present invention, a modified graphene layer is added to the multi-quantum well layer, and the graphene is modified by oxygen plasma treatment, thereby increasing the defect density of the graphene layer on the graphene surface, generating corresponding nucleation sites, which are conducive to the growth of ZnO material on the graphene layer and reducing the binding ability with the ZnO material. Then, by utilizing the resonant behavior of π electrons and π+σ electrons in the Dirac cone band structure of graphene, the graphene material will produce a surface plasmon resonance effect. When the oscillation frequency of the photon meets the dispersion relation of the plasmon oscillation of the graphene material, the plasmon of the graphene material can provide an additional radiative recombination pathway, improve the coupling with the ZnO material excitons in the ultraviolet frequency range, accelerate the radiative recombination rate of carriers in the multi-quantum well layer, reduce the non-radiative recombination process, and achieve the effect of enhancing the ultraviolet luminescence efficiency, thereby solving the problem in the existing technology that the radiative luminescence efficiency is affected by the presence of a large number of defects and impurity energy levels in the ZnO material.

[0007] According to one aspect of the above technical solution, the graphene layer is composed of 1 to 20 graphene atomic layers stacked together, including endpoint values, the power of the plasma treatment is 20W to 100W, including endpoint values, the pressure is 50Pa to 200Pa, including endpoint values, and the time is 30s to 120s, including endpoint values.

[0008] According to one aspect of the above technical solution, the multi-quantum well layer includes a ZnO quantum well layer and a ZnO quantum barrier layer to form a superlattice structure and a single-layer modified graphene layer, or the multi-quantum well layer includes a single-layer modified graphene layer, a ZnO quantum well layer and a ZnO quantum barrier layer to form a superlattice structure, or the multi-quantum well layer includes two layers of modified graphene layers, a ZnO quantum well layer and a ZnO quantum barrier layer to form a superlattice structure, the period of the superlattice structure is 1~20, including the endpoint values, the thickness of a single period is 10nm~50nm, including the endpoint values, the thickness of the ZnO quantum well layer is 2nm~10nm, including the endpoint values, and the thickness of the ZnO quantum barrier layer is 8nm~20nm, including the endpoint values.

[0009] According to one aspect of the above technical solution, when the multi-quantum well layer includes a ZnO quantum well layer and a ZnO quantum barrier layer that form a superlattice structure and a single-layer modified graphene layer, the single-layer modified graphene layer is arranged on a side close to the N-type layer or the P-type layer, and the superlattice structure includes ZnO quantum well layers and ZnO quantum barrier layers that are stacked and alternately arranged in sequence.

[0010] According to one aspect of the above technical solution, when the multi-quantum well layer includes a single-layer modified graphene layer, a ZnO quantum well layer and a ZnO quantum barrier layer to form a superlattice structure, the superlattice structure includes modified graphene layers, ZnO quantum well layers and ZnO quantum barrier layers that are stacked alternately in sequence, or the superlattice structure includes ZnO quantum well layers, modified graphene layers and ZnO quantum barrier layers that are stacked alternately in sequence, or the superlattice structure includes ZnO quantum well layers, ZnO quantum barrier layers and modified graphene layers that are stacked alternately in sequence.

[0011] According to one aspect of the above technical solution, when the multi-quantum well layer includes a superlattice structure consisting of two modified graphene layers, a ZnO quantum well layer and a ZnO quantum barrier layer, the superlattice structure includes modified graphene layers, ZnO quantum well layers, modified graphene layers and ZnO quantum barrier layers that are stacked alternately in sequence, or the superlattice structure includes ZnO quantum well layers, modified graphene layers, ZnO quantum barrier layers and modified graphene layers that are stacked alternately in sequence.

[0012] According to one aspect of the above technical solution, the ultraviolet LED epitaxial wafer also includes a barrier layer, the barrier height of the barrier layer is higher than that of the ZnO quantum barrier layer, the barrier layer includes a second barrier ZnO layer arranged between the P-type layer and the multi-quantum well layer, or the barrier layer includes a second barrier ZnO layer arranged between the P-type layer and the multi-quantum well layer and a first barrier ZnO layer arranged between the N-type layer and the multi-quantum well layer. When the barrier layer includes the second barrier ZnO layer arranged between the P-type layer and the multi-quantum well layer, the thickness of the second barrier ZnO layer is 100nm~1000nm, including the endpoint values; when the barrier layer includes the second barrier ZnO layer arranged between the P-type layer and the multi-quantum well layer and the first barrier ZnO layer arranged between the N-type layer and the multi-quantum well layer, the thickness of the first barrier ZnO layer and the second barrier ZnO layer is 100nm~1000nm, including the endpoint values.

[0013] A second aspect of the present invention is to provide a method for preparing an ultraviolet LED epitaxial wafer, the method being used to prepare the above-mentioned ultraviolet LED epitaxial wafer, the method comprising: providing a substrate; epitaxially growing an N-type layer, a multi-quantum well layer, and a P-type layer on the substrate in sequence; The multi-quantum includes a modified graphene layer, a ZnO quantum well layer, and a ZnO quantum barrier layer. The modified graphene layer is formed by wet transfer to form a graphene layer, and then formed by plasma treatment. The gas for the plasma treatment is oxygen. The power of the plasma treatment is 20W~100W, including endpoint values, the pressure is 50Pa~200Pa, including endpoint values, and the time is 30s~120s, including endpoint values.

[0014] A third aspect of the present invention is to provide an LED chip, wherein the LED chip includes the above-mentioned ultraviolet LED epitaxial wafer.

[0015] A fourth aspect of the present invention is to provide a light-emitting device, comprising the above-mentioned LED chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which: Figure 1 Schematic diagram of the structure of the ultraviolet LED epitaxial wafer in Example 1 of the present invention; Figure 2 Schematic diagram of the structure of the ultraviolet LED epitaxial wafer in Example 2 of the present invention; Figure 3 Schematic diagram of the structure of the ultraviolet LED epitaxial wafer in Example 3 of the present invention; Figure 4 Schematic diagram of the structure of the ultraviolet LED epitaxial wafer in Example 4 of the present invention; Figure 5 Schematic diagram of the structure of the ultraviolet LED epitaxial wafer in Example 5 of the present invention; Figure 6 Schematic diagram of the structure of the ultraviolet LED epitaxial wafer in Example 6 of the present invention; Figure 7 Schematic diagram of the structure of the ultraviolet LED epitaxial wafer in Example 7 of the present invention; Component symbol description in the attached figure: Substrate 10 , N-type layer 20 , first barrier ZnO layer 30 , multi-quantum well layer 40 , modified graphene layer 41 , superlattice structure 42 , second barrier ZnO layer 50 , P-type layer 60 , ZnO quantum well layer 420 , and ZnO quantum barrier layer 421 . DETAILED DESCRIPTION

[0017] To make the objectives, features, and advantages of the present invention more readily apparent, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The accompanying drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0018] The parameter ranges mentioned in this specification include the endpoint values, unless otherwise specified.

[0019] The following describes the specific embodiments.

[0020] Example 1 See also Figure 1 , shown is a UV LED epitaxial wafer provided in this embodiment, the UV LED epitaxial wafer comprising: A substrate 10 , and an N-type layer 20 , a multi-quantum well layer 40 , and a P-type layer 60 sequentially stacked on the substrate 10 .

[0021] Furthermore, the ultraviolet LED epitaxial wafer also includes a barrier layer, the barrier height of the barrier layer is higher than the ZnO quantum barrier layer 421, the barrier layer includes a second barrier ZnO layer 50 arranged between the P-type layer 60 and the multi-quantum well layer 40, or the barrier layer includes a second barrier ZnO layer 50 arranged between the P-type layer 60 and the multi-quantum well layer 40 and a first barrier ZnO layer 30 arranged between the N-type layer 20 and the multi-quantum well layer 40.

[0022] By way of example and not limitation, in this embodiment, the barrier layer includes a second barrier ZnO layer 50 disposed between the P-type layer 60 and the multi-quantum well layer 40 and a first barrier ZnO layer 30 disposed between the N-type layer 20 and the multi-quantum well layer 40. The thickness of the first barrier ZnO layer 30 and the second barrier ZnO layer 50 are both 100 nm to 1000 nm, and their doping elements include but are not limited to Al and Mg. The barrier height only needs to be higher than the ZnO quantum barrier layer 421 to limit carriers.

[0023] Furthermore, the thickness of the first barrier ZnO layer 30 and the second barrier ZnO layer 50 is 200 nm.

[0024] The multi-quantum well layer 40 includes a modified graphene layer 41, a ZnO quantum well layer 420, and a ZnO quantum barrier layer 421; It should be noted that two-dimensional (2D) graphene is a layered structure of sp2-hybridized carbon atoms with a unique honeycomb lattice. Due to the resonant behavior of π electrons and π+σ electrons within the Dirac cone band structure of graphene, graphene exhibits a surface plasmon resonance effect. Surface plasmons are collective electron oscillations occurring on the surface of a medium. This embodiment utilizes the principle that when the oscillation frequency of photons satisfies the dispersion relation of plasmon oscillations in graphene, graphene plasmons can provide additional radiative recombination pathways, thereby improving the internal quantum efficiency (IQE) of LED chips. Specifically, they can couple with ZnO excitons within the ultraviolet frequency range, accelerating the radiative recombination rate of carriers in the multi-quantum well layer 40, reducing non-radiative recombination processes, and enhancing the ultraviolet luminescence efficiency of the ZnO material.

[0025] Furthermore, due to the lack of dangling bonds and nucleation sites on the graphene surface, and the lattice mismatch with the ZnO material, ZnO material is difficult to grow directly on the surface of a structurally intact graphene material. Therefore, the graphene layer is modified. The modified graphene layer 41 is a graphene layer that has been plasma-treated. The plasma treatment gas is oxygen, and the plasma treatment power is 20W to 100W, the pressure is 50Pa to 200Pa, and the time is 30s to 120s. Oxygen plasma treatment increases the defect density of the graphene layer, thereby generating corresponding nucleation sites. During the oxygen plasma treatment, the graphene layer generates some CO dangling chemical bonds, oxygen-containing functional groups, or defect sites, which are used for oxide nucleation and growth, facilitating the growth of ZnO material on the graphene layer. Furthermore, ZnO material with the lowest binding energy (0001) plane is obtained, thus exhibiting a c-axis preferential growth advantage.

[0026] The multi-quantum well layer 40 includes a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure and a single-layer modified graphene layer 41, or the multi-quantum well layer 40 includes a single-layer modified graphene layer 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure, or the multi-quantum well layer 40 includes two layers of modified graphene layers 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure.

[0027] In this embodiment, when the multi-quantum well layer 40 includes the ZnO quantum well layer 420 and the ZnO quantum barrier layer 421 forming a superlattice structure and a single-layer modified graphene layer 41, the single-layer modified graphene layer 41 is arranged on a side close to the N-type layer 20 or the P-type layer 60.

[0028] Furthermore, a single-layer modified graphene layer 41 is arranged on the side close to the N-type layer 20, and the superlattice structure 42 includes a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 that are stacked and alternately arranged in sequence. The period of the superlattice structure 42 is 1 to 20, the thickness of a single period is 10 nm to 50 nm, the thickness of the ZnO quantum well layer 420 is 2 nm to 10 nm, and the thickness of the ZnO quantum barrier layer 421 is 8 nm to 20 nm.

[0029] Preferably, the period of the superlattice structure 42 is 8, the thickness of a single period is 30 nm, the thickness of the ZnO quantum well layer 420 is 10 nm, and the thickness of the ZnO quantum barrier layer 421 is 20 nm.

[0030] The ZnO quantum well layer 420 / ZnO quantum barrier layer 421 includes but is not limited to ZnO / ZnMgO, ZnO / ZnAlO, etc. The doping concentration of the ZnO quantum well layer 420 / ZnO quantum barrier layer 421 is 0.05% to 0.5%, and the doping concentration can be constant or linearly variable.

[0031] Furthermore, the modified graphene layer 41 is formed by wet transfer to form a graphene layer, which is then formed by plasma treatment. The graphene layer is formed by stacking 1 to 20 graphene atomic layers. The gas for the plasma treatment is oxygen. The power of the plasma treatment is 20W to 100W, the pressure is 50Pa to 200Pa, and the time is 30s to 120s.

[0032] The graphene layer is formed by stacking two graphene atomic layers.

[0033] In addition, the N-type layer 20 and the P-type layer 60 are GaN layers doped with different elements.

[0034] Furthermore, the purpose of setting the first barrier ZnO layer 30 and the second barrier ZnO layer 50 above and below the multi-quantum well layer 40 is to reduce the recombination of carriers in the interface, N-type layer 20, and P-type layer 60, confine the carriers in the multi-quantum well layer 40, increase the ZnO exciton radiative recombination, and increase the luminous efficiency.

[0035] Accordingly, the method for preparing the ultraviolet LED epitaxial wafer includes the following steps: Step S10, providing a substrate 10; The substrate 10 may be a sapphire substrate, a SiC substrate, a Si substrate, or a GaN substrate.

[0036] Preferably, the substrate in this embodiment is a sapphire substrate.

[0037] Step S11, epitaxially growing an N-type layer 20, a multi-quantum well layer 40, and a P-type layer 60 on the substrate 10 in sequence; Furthermore, a first barrier ZnO layer 30 is grown between the N-type layer 20 and the multi-quantum well layer 40 , and a second barrier ZnO layer 50 is grown between the P-type layer 60 and the multi-quantum well layer 40 .

[0038] The thickness of the first barrier ZnO layer 30 and the second barrier ZnO layer 50 is 100 nm to 1000 nm; The multi-quantum well layer 40 includes a modified graphene layer 41, a ZnO quantum well layer 420, and a ZnO quantum barrier layer 421. The modified graphene layer 41 is formed into a graphene layer by wet transfer, and then formed by plasma treatment. The gas for the plasma treatment is oxygen, the power of the plasma treatment is 20W~100W, the pressure is 50Pa~200Pa, and the time is 30s~120s.

[0039] Furthermore, two graphene layers are transferred by a wet method, and then plasma treatment is performed on the surface to form a modified graphene layer 41.

[0040] Furthermore, this embodiment also provides an LED chip, which includes the above-mentioned ultraviolet LED epitaxial wafer.

[0041] In addition, this embodiment further provides a light-emitting device, which includes the above-mentioned LED chip. The light-emitting device also includes a lighting device, a display device, etc.

[0042] Example 2 See also Figure 2 , which shows a UV LED epitaxial wafer provided by the second embodiment of the present invention. The difference between the UV LED epitaxial wafer in this embodiment and the UV LED epitaxial wafer in the first embodiment is that: The single modified graphene layer 41 is disposed on a side close to the P-type layer 60 .

[0043] Example 3 See also Figure 3 , which shows a UV LED epitaxial wafer provided by the third embodiment of the present invention. The UV LED epitaxial wafer in this embodiment differs from the UV LED epitaxial wafer in the first embodiment in that: The multi-quantum well layer 40 includes a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure and a single-layer modified graphene layer 41, or the multi-quantum well layer 40 includes a single-layer modified graphene layer 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure, or the multi-quantum well layer 40 includes two layers of modified graphene layers 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure.

[0044] In this embodiment, the multi-quantum well layer 40 includes a single-layer modified graphene layer 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure. The superlattice structure includes the modified graphene layer 41, the ZnO quantum well layer 420 and the ZnO quantum barrier layer 421 stacked and alternately arranged in sequence.

[0045] Example 4 See also Figure 4 , shown is a UV LED epitaxial wafer provided by the fourth embodiment of the present invention. The difference between the UV LED epitaxial wafer in this embodiment and the UV LED epitaxial wafer in the first embodiment is that: The multi-quantum well layer 40 includes a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure and a single-layer modified graphene layer 41, or the multi-quantum well layer 40 includes a single-layer modified graphene layer 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure, or the multi-quantum well layer 40 includes two layers of modified graphene layers 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure.

[0046] In this embodiment, the multi-quantum well layer 40 includes a single-layer modified graphene layer 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure. The superlattice structure includes the ZnO quantum well layer 420, the modified graphene layer 41 and the ZnO quantum barrier layer 421 stacked and alternately arranged in sequence.

[0047] Example 5 See also Figure 5 , which shows a UV LED epitaxial wafer provided by the fifth embodiment of the present invention. The difference between the UV LED epitaxial wafer in this embodiment and the UV LED epitaxial wafer in the first embodiment is that: The multi-quantum well layer 40 includes a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure and a single-layer modified graphene layer 41, or the multi-quantum well layer 40 includes a single-layer modified graphene layer 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure, or the multi-quantum well layer 40 includes two layers of modified graphene layers 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure.

[0048] In this embodiment, the multi-quantum well layer 40 includes a single-layer modified graphene layer 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure. The superlattice structure includes the ZnO quantum well layer 420, the ZnO quantum barrier layer 421 and the modified graphene layer 41 stacked and alternately arranged in sequence.

[0049] Example 6 See also Figure 6 , which shows a UV LED epitaxial wafer provided by the sixth embodiment of the present invention. The difference between the UV LED epitaxial wafer in this embodiment and the UV LED epitaxial wafer in the first embodiment is that: The multi-quantum well layer 40 includes a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure and a single-layer modified graphene layer 41, or the multi-quantum well layer 40 includes a single-layer modified graphene layer 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure, or the multi-quantum well layer 40 includes two layers of modified graphene layers 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure.

[0050] In this embodiment, the multi-quantum well layer 40 includes a superlattice structure consisting of two modified graphene layers 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421. The superlattice structure includes modified graphene layers 41, ZnO quantum well layers 420, modified graphene layers 41 and ZnO quantum barrier layers 421 stacked and alternately arranged in sequence.

[0051] Example 7 See also Figure 7 , which shows a UV LED epitaxial wafer provided by the seventh embodiment of the present invention. The difference between the UV LED epitaxial wafer in this embodiment and the UV LED epitaxial wafer in the first embodiment is that: The multi-quantum well layer 40 includes a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure and a single-layer modified graphene layer 41, or the multi-quantum well layer 40 includes a single-layer modified graphene layer 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure, or the multi-quantum well layer 40 includes two layers of modified graphene layers 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421 to form a superlattice structure.

[0052] In this embodiment, the multi-quantum well layer 40 includes a superlattice structure consisting of two modified graphene layers 41, a ZnO quantum well layer 420 and a ZnO quantum barrier layer 421. The superlattice structure includes ZnO quantum well layers 420, modified graphene layers 41, ZnO quantum barrier layers 421 and modified graphene layers 41 stacked and alternately arranged in sequence.

[0053] By way of example and not limitation, in the remaining embodiments, the multi-quantum well layer of the present invention may be any pairs within the periodic number using a single-layer modified graphene layer, a ZnO quantum well layer and a ZnO quantum barrier layer to form a superlattice structure, or the multi-quantum well layer may be any pairs within the periodic number using two layers of modified graphene layer, a ZnO quantum well layer and a ZnO quantum barrier layer to form a superlattice structure, while the rest maintain an arrangement of alternating stacked ZnO quantum well layers and ZnO quantum barrier layers.

[0054] Comparative Example 1 The first comparative example of the present invention provides an ultraviolet LED epitaxial wafer. The difference between the ultraviolet LED epitaxial wafer in this comparative example and the ultraviolet LED epitaxial wafer in the first embodiment is that: No modified graphene layer was added.

[0055] Comparative Example 2 The second comparative example of the present invention provides an ultraviolet LED epitaxial wafer. The difference between the ultraviolet LED epitaxial wafer in this comparative example and the ultraviolet LED epitaxial wafer in the first embodiment is that: No plasma treatment was performed.

[0056] Please refer to the table below, which shows the performance test results of ultraviolet LED epitaxial wafers prepared under different embodiments and comparative examples.

[0057] Table 1:

[0058] Among them, the ultraviolet LED epitaxial wafers were made into 22mil×35mil under the same process conditions. 300 ultraviolet LED epitaxial wafers were sampled and their performance was tested at a current of 60mA. The improvement in luminous efficiency was calculated based on the luminous efficiency of comparative example 1.

[0059] According to Table 1, adding a modified graphene layer into the multi-quantum well layer can effectively improve the light efficiency.

[0060] Furthermore, according to Examples 1 to 2, 3 to 5, and 6 to 7, the UV LED epitaxial wafer prepared by placing the modified graphene layer below the ZnO quantum well layer has a higher light efficiency improvement rate than the UV LED epitaxial wafer prepared by placing it above the ZnO quantum well layer.

[0061] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0062] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0063] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A UV LED epitaxial wafer, characterized in that: The ultraviolet LED epitaxial wafer comprises: A substrate, and an N-type layer, a multi-quantum well layer, and a P-type layer sequentially stacked on the substrate; The multi-quantum well layer includes a modified graphene layer, a ZnO quantum well layer, and a ZnO quantum barrier layer; The modified graphene layer is a graphene layer that has been treated with plasma, and the gas used for the plasma treatment is oxygen.

2. The ultraviolet LED epitaxial wafer according to claim 1, characterized in that The graphene layer is composed of 1 to 20 graphene atomic layers stacked together, including endpoint values. The power of the plasma treatment is 20W to 100W, including endpoint values, the pressure is 50Pa to 200Pa, including endpoint values, and the time is 30s to 120s, including endpoint values.

3. The ultraviolet LED epitaxial wafer according to claim 1, characterized in that: The multi-quantum well layer includes a ZnO quantum well layer and a ZnO quantum barrier layer to form a superlattice structure and a single-layer modified graphene layer, or the multi-quantum well layer includes a single-layer modified graphene layer, a ZnO quantum well layer and a ZnO quantum barrier layer to form a superlattice structure, or the multi-quantum well layer includes two modified graphene layers, a ZnO quantum well layer and a ZnO quantum barrier layer to form a superlattice structure, the period of the superlattice structure is 1~20, including the endpoint values, the thickness of a single period is 10nm~50nm, including the endpoint values, the thickness of the ZnO quantum well layer is 2nm~10nm, including the endpoint values, and the thickness of the ZnO quantum barrier layer is 8nm~20nm, including the endpoint values.

4. The ultraviolet LED epitaxial wafer according to claim 3, characterized in that: When the multi-quantum well layer includes a ZnO quantum well layer and a ZnO quantum barrier layer to form a superlattice structure and a single-layer modified graphene layer, the single-layer modified graphene layer is arranged on a side close to the N-type layer or the P-type layer, and the superlattice structure includes ZnO quantum well layers and ZnO quantum barrier layers that are stacked and alternately arranged in sequence.

5. The ultraviolet LED epitaxial wafer according to claim 3, characterized in that: When the multi-quantum well layer includes a single-layer modified graphene layer, a ZnO quantum well layer and a ZnO quantum barrier layer to form a superlattice structure, the superlattice structure includes modified graphene layers, ZnO quantum well layers and ZnO quantum barrier layers that are stacked alternately in sequence, or the superlattice structure includes ZnO quantum well layers, modified graphene layers and ZnO quantum barrier layers that are stacked alternately in sequence, or the superlattice structure includes ZnO quantum well layers, ZnO quantum barrier layers and modified graphene layers that are stacked alternately in sequence.

6. The ultraviolet LED epitaxial wafer according to claim 3, characterized in that: When the multi-quantum well layer includes a superlattice structure consisting of two modified graphene layers, a ZnO quantum well layer and a ZnO quantum barrier layer, the superlattice structure includes modified graphene layers, ZnO quantum well layers, modified graphene layers and ZnO quantum barrier layers stacked alternately in sequence, or the superlattice structure includes ZnO quantum well layers, modified graphene layers, ZnO quantum barrier layers and modified graphene layers stacked alternately in sequence.

7. The ultraviolet LED epitaxial wafer according to claim 1, characterized in that: The ultraviolet LED epitaxial wafer also includes a barrier layer, the barrier height of the barrier layer is higher than that of the ZnO quantum barrier layer, the barrier layer includes a second barrier ZnO layer arranged between the P-type layer and the multi-quantum well layer, or the barrier layer includes a second barrier ZnO layer arranged between the P-type layer and the multi-quantum well layer and a first barrier ZnO layer arranged between the N-type layer and the multi-quantum well layer. When the barrier layer includes the second barrier ZnO layer arranged between the P-type layer and the multi-quantum well layer, the thickness of the second barrier ZnO layer is 100nm~1000nm, including the endpoint values; when the barrier layer includes the second barrier ZnO layer arranged between the P-type layer and the multi-quantum well layer and the first barrier ZnO layer arranged between the N-type layer and the multi-quantum well layer, the thickness of the first barrier ZnO layer and the second barrier ZnO layer are both 100nm~1000nm, including the endpoint values.

8. A method for preparing a UV LED epitaxial wafer, characterized in that: The preparation method is used to prepare the ultraviolet LED epitaxial wafer according to any one of claims 1 to 7, and the preparation method comprises: providing a substrate; epitaxially growing an N-type layer, a multi-quantum well layer, and a P-type layer on the substrate in sequence; The multi-quantum includes a modified graphene layer, a ZnO quantum well layer, and a ZnO quantum barrier layer. The modified graphene layer is formed by wet transfer to form a graphene layer, and then formed by plasma treatment. The gas for the plasma treatment is oxygen. The power of the plasma treatment is 20W~100W, including endpoint values, the pressure is 50Pa~200Pa, including endpoint values, and the time is 30s~120s, including endpoint values.

9. An LED chip, characterized in that: The LED chip comprises the ultraviolet LED epitaxial wafer according to any one of claims 1 to 7.

10. A light emitting device, characterized in that: The light-emitting device comprises the LED chip according to claim 9.

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