Semiconductor light-emitting element

Abstract

The utility model provides a semiconductor light-emitting element, which sequentially comprises a substrate, a buffer layer, an unintentional doping layer, an n-type semiconductor layer, an active layer and a p-type semiconductor layer from bottom to top, and the buffer layer is a periodic structure formed by alternate growth of an Al2O3 layer, an AlON layer and an AlN layer. According to the utility model, through the design of the buffer layer, lattice mismatch and thermal mismatch of the semiconductor light-emitting element can be effectively relieved, and meanwhile, the problem of stress accumulation can be avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductors, and particularly relates to a semiconductor light-emitting element. Background Art

[0002] Semiconductor light-emitting elements have a wide wavelength tunable range, high luminous efficiency, energy conservation and environmental protection, long service life, small size, and strong designability. They have gradually replaced incandescent lamps and fluorescent lamps and become the light source for general household lighting, and are widely used in new scenarios, such as Mini-LED (sub-millimeter light-emitting diodes), indoor high-resolution displays, outdoor displays, mobile phone backlights, TV backlights, laptop backlights, household lamps, street lamps, vehicle lamps, and flashlights, etc.

[0003] However, in GaN (gallium nitride)-based semiconductor light-emitting elements, GaN is usually heteroepitaxially grown on other material substrates, such as sapphire, SiC, and Si substrates. Heteroepitaxy will have differences in lattice and thermal expansion coefficients, resulting in stress and affecting crystal quality. Currently, PVD (physical vapor deposition) is mostly used in the industry to deposit AlN as a buffer layer to reduce stress. However, a single AlN buffer layer can only reduce a certain lattice mismatch. If better buffering is required, a thicker AlN buffer layer is needed. If a single AlN buffer layer is grown too thick, the stress between the substrate and the AlN buffer layer will also increase. When the stress accumulates to a certain extent, the epitaxial wafer is prone to cracking, and the warping will become concave.

[0004] Therefore, it is necessary to provide a new buffer layer structure to have a better stress buffering effect and avoid the stress accumulation problem caused by growing a single AlN buffer layer too thick. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a semiconductor light-emitting element to effectively alleviate the lattice mismatch and thermal mismatch of the semiconductor light-emitting element, and at the same time avoid the stress accumulation problem.

[0006] To achieve the above purpose and other related purposes, the utility model provides a semiconductor light-emitting element, which sequentially includes from bottom to top: a substrate, a buffer layer, an unintentionally doped layer, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer, wherein the buffer layer is a periodic structure formed by alternating growth of an Al 2 O 3 layer, an AlON layer, and an AlN layer.

[0007] Optionally, in the semiconductor light-emitting element, the structural layer on the side of the buffer layer close to the substrate is any one of an Al 2 O 3 layer, an AlON layer, and an AlN layer.

[0008] Optionally, in the semiconductor light-emitting element, the structural layer of the buffer layer close to the unintentionally doped layer side is any one of an AlN layer and an AlON layer.

[0009] Optionally, in the semiconductor light-emitting element, the structure of each period of the buffer layer is an Al 2 O 3 layer, an AlON layer, and an AlN layer stacked in sequence from bottom to top. The Al 2 O 3 layer is located on the substrate, and the unintentionally doped layer is located on the AlN layer.

[0010] Optionally, in the semiconductor light-emitting element, the number of periods of the buffer layer is 1 to 10.

[0011] Optionally, in the semiconductor light-emitting element, the total thickness of the buffer layer is 10 nm to 100 nm.

[0012] Optionally, in the semiconductor light-emitting element, the thickness of a single period of the AlN layer is 1 nm to 5 nm.

[0013] Optionally, in the semiconductor light-emitting element, the thickness of a single period of the AlON layer is 1 nm to 5 nm.

[0014] Optionally, in the semiconductor light-emitting element, the Al 2 O 3 layer has a single-period thickness of 1 nm to 5 nm.

[0015] Optionally, in the semiconductor light-emitting element, the semiconductor light-emitting element further includes an electron blocking layer, and the electron blocking layer is located between the active layer and the p-type semiconductor layer.

[0016] Optionally, in the semiconductor light-emitting element, the substrate is a sapphire substrate, a SiC substrate, or a Si substrate.

[0017] Compared with the prior art, the technical solution of the present utility model has the following beneficial effects:

[0018] In the semiconductor light-emitting element provided by the present utility model, the buffer layer is Al 2 O 3The periodic structure formed by the alternating growth of the AlO layer, the AlON layer, and the AlN layer can reduce the lattice mismatch and thermal mismatch, achieving a better buffering effect. Moreover, the superposition of the three structural layers can avoid the stress accumulation of a single structural layer, and the superposition of the three structural layers can enable the buffer layer to grow thicker under the cooperation of compressive stress and tensile stress. In addition, the use of a periodic structure can also prevent the stress accumulation caused by the over-thick growth of a single structural layer, thereby preventing the deterioration of crystal quality. Description of the Drawings

[0019] Figure 1 is a schematic structural diagram of a semiconductor light-emitting element according to an embodiment of the present invention;

[0020] Figure 2 is a schematic structural diagram of a buffer layer according to an embodiment of the present invention;

[0021] Figures 1 to 2 In:

[0022] 100 - Substrate, 200 - Buffer layer, 201 - Al 2 O 3 layer, 202 - AlON layer, 203 - AlN layer, 300 - Unintentionally doped layer, 400 - n-type semiconductor layer, 500 - Active layer, 600 - Electron blocking layer, 700 - p-type semiconductor layer. Detailed Embodiment

[0023] The semiconductor light-emitting element proposed by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0024] Refer to Figure 1 and Figure 2 , the present invention provides a semiconductor light-emitting element, which sequentially includes from bottom to top: a substrate 100, a buffer layer 200, an unintentionally doped layer 300, an n-type semiconductor layer 400, an active layer 500, and a p-type semiconductor layer 700, wherein the buffer layer 200 is a periodic structure formed by the alternating growth of an Al 2 O 3 layer 201, an AlON layer 202, and an AlN layer 203.

[0025] In this embodiment, the semiconductor light-emitting element may further include an electron blocking layer 600, which is located between the active layer 500 and the p-type semiconductor layer 700 and is mainly used to block the overflow of electrons.

[0026] In this embodiment, the buffer layer 200 is Al 2 O3 A periodic structure formed by alternating growth of AlO layer 201, AlON layer 202 and AlN layer 203, the number of periods can be 1 to 10, preferably 5 to 10. The structural layer of the buffer layer 200 close to the substrate 100 side is any one of AlN layer 203, AlON layer 202 and Al 2 O 3 any layer in layer 201. And due to the large difference in lattice constant between the Al 2 O 3 layer 201 and the lattice constant of GaN, when growing the epitaxial structure of GaN (i.e., the unintentionally doped layer 300) on the Al 2 O 3 layer 201, serious lattice mismatch will occur. Therefore, the structural layer of the buffer layer 200 close to the unintentionally doped layer 300 side is any one of AlN layer 203 and AlON layer 202. The buffer layer 200 of this embodiment adopts Al 2 O 3 A periodic structure formed by alternating growth of layer 201, AlON layer 202 and AlN layer 203 can reduce lattice mismatch and thermal mismatch, and can achieve a better buffering effect; moreover, the superposition of the three structural layers can avoid stress accumulation of a single structural layer, and the superposition of the three structural layers can make the buffer layer 200 grow thicker under the cooperation of compressive stress and tensile stress; in addition, using a periodic structure can also prevent stress accumulation caused by a single structural layer growing too thick, thereby preventing the crystal quality from deteriorating.

[0027] The semiconductor light-emitting element of this embodiment is preferably a GaN-based semiconductor light-emitting element, and more preferably a GaN-based light-emitting diode (LED). The manufacturing method of the semiconductor light-emitting element may include the following steps:

[0028] Step S1: Provide a substrate 100;

[0029] Step S2: Grow a buffer layer 200 on the substrate 100, and the buffer layer 200 is a periodic structure formed by alternating growth of Al 2 O 3 layer 201, AlON layer 202 and AlN layer 203;

[0030] Step S3: Sequentially grow an unintentionally doped layer 300, an n-type semiconductor layer 400, an active layer 500 and a p-type semiconductor layer 700 on the buffer layer 200.

[0031] Execute step S1 to provide a substrate 100. The substrate 100 can be a sapphire substrate, a SiC substrate or a Si substrate, but is not limited thereto. Further, the substrate 100 is preferably a sapphire substrate.

[0032] Perform step S2 to grow a buffer layer 200 on the substrate 100. In this embodiment, the buffer layer 200 is preferably Al 2 O 3 A periodic structure formed by alternately growing layer 201, AlON layer 202, and AlN layer 203. The preparation process of the buffer layer 200 is preferably a PVD (Physical Vapor Deposition) process, that is, on the substrate 100, use the PVD process to grow the periodic structure of Al 2 O 3 Layer 201, AlON layer 202, and AlN layer 203. The growth temperature of the PVD process is preferably 500°C to 700°C, such as 600°C. In this embodiment, when growing the AlON layer 202, the nitrogen-oxygen partial pressure ratio is controlled at 10:1 to 60:1, that is, the O component in the AlON layer 202 can be 0% to 5%, and the N component can be 95% to 100%.

[0033] In this embodiment, the material of the AlN layer 203 is preferably AlN, the material of the AlON layer 202 is preferably AlON, and the Al 2 O 3 The material of layer 201 is preferably Al 2 O 3 , that is, the buffer layer 200 is a combination of three materials: AlN, AlON, and Al 2 O 3 The number of periods of the buffer layer 200 can be 1 to 10, preferably 5 to 10. In this embodiment, the total thickness of the buffer layer 200 can be 10 nm to 100 nm, preferably 25 nm to 80 nm; the single-period thickness of the AlN layer 203 can be 1 nm to 5 nm, preferably 2 nm to 3 nm; the single-period thickness of the AlON layer 202 can be 1 nm to 5 nm, preferably 2 nm to 3 nm; the single-period thickness of the Al 2 O 3 Layer 201 can be 1 nm to 5 nm, preferably 1 nm to 2 nm.

[0034] In this embodiment, the lattice constant size order is: Al 2 O 3 >GaN>AlN>AlON. Since the lattice constant of the substrate 100 is the largest, the lattice constant of the structure formed by superimposing the other three materials will also be smaller than the lattice constant of the substrate 100. Thus, the substrate 100 will be under compressive stress and the lattice will become smaller, reducing the lattice constant gap with the GaN epitaxial structure; therefore, the materials in contact with the substrate 100 are AlN, AlON, and Al 2 O 3Any one of them is acceptable. That is, the structural layer on the side of the buffer layer 200 close to the substrate 100 can be the AlN layer 203, the AlON layer 202, and the Al 2 O 3 layer 201. Since the lattice constant of the Al 2 O 3 layer 201 is quite different from that of GaN, serious lattice mismatch will occur when growing the GaN epitaxial structure (i.e., the unintentionally doped layer 300) on the Al 2 O 3 layer 201. Therefore, the structural layer on the side of the buffer layer 200 close to the unintentionally doped layer 300 is preferably any one of the AlN layer 203 and the AlON layer 202. For example, the structure of each period of the buffer layer 200 is the AlN layer 203, the Al 2 O 3 layer 201, and the AlON layer 202 stacked in sequence from bottom to top. The AlN layer 203 is located on the substrate 100, and the unintentionally doped layer 300 is located on the AlON layer 202. Another example, the structure of each period of the buffer layer 200 is the Al 2 O 3 layer 201, the AlN layer 203, and the AlON layer 202 stacked in sequence from bottom to top. The Al 2 O 3 layer 201 is located on the substrate 100, and the unintentionally doped layer 300 is located on the AlON layer 202. Another example, the structure of each period of the buffer layer 200 is the Al 2 O 3 layer 201, the AlON layer 202, and the AlN layer 203 stacked in sequence from bottom to top. The Al 2 O 3 layer 201 is located on the substrate 100, and the unintentionally doped layer 300 is located on the AlN layer 203. Another example, the structure of each period of the buffer layer 200 is the AlON layer 202, the Al 2 O 3 layer 201, and the AlN layer 203 stacked in sequence from bottom to top. The AlON layer 202 is located on the substrate 100, and the unintentionally doped layer 300 is located on the AlN layer 203. In this embodiment, the most preferred structure of each period of the buffer layer 200 is the Al 2 O 3 layer 201, the AlON layer 202, and the AlN layer 203 stacked in sequence from bottom to top. The Al 2 O 3The layer 201 is located on the substrate 100, and the unintentionally doped layer 300 is located on the AlN layer 203. Adopting this structure can relieve lattice mismatch, reduce dislocation density, and improve the ESD yield of the semiconductor light-emitting device by about 3% and the brightness by about 2%.

[0035] In a GaN-based semiconductor light-emitting device, during the GaN epitaxial growth, due to lattice mismatch and thermal mismatch, the crystal quality cannot reach a perfect state, and some defects will occur, resulting in poor crystal quality. The stress generated by lattice mismatch and thermal mismatch will also change the warping of the epitaxial wafer, making the optoelectronic parameters of the epitaxial wafer uneven. Even when the stress accumulates to a certain extent, the epitaxial wafer will crack. In the conventional epitaxial process, a PVD process is used to deposit an AlN layer as a buffer layer. Since the lattice constant of AlN is smaller than that of the substrate, the substrate is subjected to compressive stress, so that the lattice constant of the substrate decreases, making the mismatch between the substrate and the AlN buffer layer and the subsequently grown GaN smaller. However, a single AlN buffer layer can only reduce a certain lattice mismatch. If better buffering is required, a thicker buffer layer is needed. If a single AlN buffer layer grows too thick, the stress between the substrate and the AlN layer will also increase. When it accumulates to a certain extent, the epitaxial wafer is prone to cracking and the warping will become concave. In this embodiment, by designing a buffer layer 200 formed by three structural layers of an AlN layer, an AlON layer, and an Al 2 O 3 layer, the lattice constant difference can be reduced and the thermal mismatch can be decreased, achieving a better buffering effect. The buffer layer 200 of this embodiment also has the following beneficial effects: First, the superposition of the three structural layers can avoid the stress accumulation of a single structural layer, and the superposition of the three structural layers can make the buffer layer 200 grow thicker under the cooperation of compressive stress and tensile stress. Second, the use of a periodic structure can also prevent a single structural layer from growing too thick, resulting in stress accumulation, thereby preventing the crystal quality from deteriorating.

[0036] Execute step S3. After the step of growing the buffer layer 200, an unintentionally doped layer 300 is grown on the buffer layer 200. The unintentionally doped layer 300 has an unintentionally doped structure. The material of the unintentionally doped layer 300 is preferably GaN. The thickness of the unintentionally doped layer 300 can be set according to the thickness of the unintentionally doped layer in the existing GaN-based semiconductor light-emitting device, which will not be elaborated here.

[0037] After the step of growing the unintentionally doped layer 300, an n-type semiconductor layer 400 is grown on the unintentionally doped layer 300. In this embodiment, the material of the n-type semiconductor layer 400 is preferably GaN, but is not limited thereto. The n-type semiconductor layer 400 is doped with an n-type dopant, and the n-type dopant is preferably Si, but is not limited thereto. The thickness of the n-type semiconductor layer 400 can be set to the thickness of the n-type semiconductor layer in existing GaN-based semiconductor light-emitting elements, which will not be elaborated here.

[0038] After the step of growing the n-type semiconductor layer 400, an active layer 500 is grown on the n-type semiconductor layer 400. The active layer 500 mainly serves as a light-emitting layer. The active layer 500 is preferably a multi-quantum well structure, that is, the active layer 500 is preferably a periodic structure composed of quantum wells and quantum barriers. The material of the quantum well is preferably InGaN, but is not limited thereto. The material of the quantum barrier is preferably AlGaN, but is not limited thereto. The thickness of the active layer 500 can be set to the thickness of the active layer in existing GaN-based semiconductor light-emitting elements, which will not be elaborated here.

[0039] The semiconductor light-emitting element of this embodiment may include an electron blocking layer 600, and the electron blocking layer 600 is located between the active layer 500 and the p-type semiconductor layer 700. Therefore, after the step of growing the active layer 500, an electron blocking layer 600 is grown on the active layer 500. The material of the electron blocking layer 600 is preferably AlGaN, but is not limited thereto. The thickness of the electron blocking layer 600 can be set to the thickness of the electron blocking layer in existing GaN-based semiconductor light-emitting elements, which will not be elaborated here.

[0040] After the step of growing the electron blocking layer 600, a p-type semiconductor layer 700 is grown on the electron blocking layer 600. In this embodiment, the material of the p-type semiconductor layer 700 is preferably GaN, but is not limited thereto. The p-type semiconductor layer 700 is doped with a p-type dopant, and the p-type dopant is preferably Mg, but is not limited thereto. The thickness of the p-type semiconductor layer 700 can be set to the thickness of the p-type semiconductor layer in existing GaN-based semiconductor light-emitting elements, which will not be elaborated here.

[0041] The preparation processes of the unintentional doping layer 300, n-type semiconductor layer 400, active layer 500, electron blocking layer 600 and p-type semiconductor layer 700 in this embodiment can be any one of MOCVD (Metal-organic Chemical Vapor Deposition), molecular beam epitaxy process and UHVCVD (Ultrahigh Vacuum Chemical Vapor Deposition) process, and preferably MOCVD process.

[0042] In summary, the buffer layer of the present utility model is an Al 2 O 3 layer, a periodic structure formed by the alternating growth of AlON layers and AlN layers, which can reduce lattice mismatch and thermal mismatch, and can achieve a better buffering effect; moreover, the superposition of the three structural layers can avoid stress accumulation in a single structural layer, and the superposition of the three structural layers can make the buffer layer grow thicker under the cooperation of compressive stress and tensile stress; in addition, the use of a periodic structure can also prevent stress accumulation caused by the over-thick growth of a single structural layer, thereby preventing the deterioration of crystal quality.

[0043] In addition, it can be understood that although the present utility model has been disclosed above with preferred embodiments, the above embodiments are not intended to limit the present utility model. For any person skilled in the art, without departing from the scope of the technical solution of the present utility model, many possible changes and modifications can be made to the technical solution of the present utility model by using the above-disclosed technical content, or modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present utility model without departing from the content of the technical solution of the present utility model still fall within the scope of protection of the technical solution of the present utility model.

[0044] Moreover, it should also be understood that the present utility model is not limited to the specific methods, compounds, materials, manufacturing techniques, usages and applications described herein, and they 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 present utility model. It must be noted that the singular forms "a", "an" and "the" used herein and in the appended claims include plural references unless the context clearly dictates otherwise. Thus, for example, a reference to "a step" means a reference to one or more steps and may include sub-steps. All conjunctions used should be understood in their broadest sense. Thus, the word "or" should be understood to have the definition of logical "or", rather than the definition of logical "exclusive or", unless the context clearly dictates otherwise. The structures described herein will be understood to also refer to functional equivalents of such structures. Language that may be construed as approximate should be so understood unless the context clearly dictates otherwise.

Claims

1. A semiconductor light emitting element, characterized in that: The invention comprises, from bottom to top, a substrate, a buffer layer, an unintentionally doped layer, an n-type semiconductor layer, an active layer and a p-type semiconductor layer, wherein the buffer layer is a periodic structure formed by the alternating growth of an Al2O3 layer, an AlON layer and an AlN layer.

2. The semiconductor light emitting element according to claim 1, wherein The structural layer in the buffer layer close to the substrate is any one of an Al2O3 layer, an AlON layer and an AlN layer.

3. The semiconductor light emitting element according to claim 1, wherein: The structural layer in the buffer layer close to the unintentionally doped layer is any one of an AlN layer and an AlON layer.

4. The semiconductor light emitting element according to claim 1, wherein: The structure of each period of the buffer layer is an Al2O3 layer, an AlON layer and an AlN layer stacked in sequence from bottom to top, the Al2O3 layer is located on the substrate, and the unintentionally doped layer is located on the AlN layer.

5. The semiconductor light emitting element according to claim 1, wherein: The number of periods of the buffer layer is 1-10.

6. The semiconductor light emitting element according to claim 1, wherein: The total thickness of the buffer layer is 10 nm to 100 nm.

7. The semiconductor light emitting element according to claim 6, wherein: The single-period thickness of the AlN layer is 1 nm to 5 nm.

8. The semiconductor light emitting element according to claim 6, wherein: The single-period thickness of the AlON layer is 1 nm to 5 nm.

9. The semiconductor light emitting element according to claim 6, wherein: The single-period thickness of the Al2O3 layer is 1 nm to 5 nm.

10. The semiconductor light emitting element according to claim 1, wherein: The semiconductor light emitting element further includes an electron blocking layer, and the electron blocking layer is located between the active layer and the p-type semiconductor layer.

11. The semiconductor light emitting element according to claim 1, wherein: The substrate is a sapphire substrate, a SiC substrate or a Si substrate.

Images