Semiconductor epitaxial structure and manufacturing method thereof, LED chip

Abstract

The application provides a semiconductor epitaxial structure, a manufacturing method thereof and an LED chip. A defect blocking layer, a first N-type semiconductor layer, a current blocking layer, a second N-type semiconductor layer, an active layer and a P-type semiconductor layer are sequentially stacked on the surface of the substrate. The defect blocking layer blocks the upward extension of defects generated between the substrate and the semiconductor layer due to lattice mismatch. Meanwhile, the current blocking layer blocks the longitudinal transmission of current on the surface of the second N-type semiconductor layer, improves the lateral transmission of current at the interface and increases the current spreading effect.

Description

Technical Field

[0001] This invention relates to the field of light-emitting diodes, and more particularly to a semiconductor epitaxial structure and its fabrication method, and an LED chip. Background Technology

[0002] A light-emitting diode (LED) is a semiconductor electronic component that emits light. LEDs offer advantages such as high efficiency, long lifespan, small size, and low power consumption, making them suitable for indoor and outdoor white light lighting, screen displays, and backlighting. In the development of the LED industry, gallium nitride (GaN)-based materials are a typical representative of V-III compound semiconductors, and improving the photoelectric performance of GaN-based LEDs has become crucial for the semiconductor lighting industry.

[0003] Epitaxial wafers are the initial finished products in the LED manufacturing process. Existing GaN-based LED epitaxial wafers include a substrate, an N-type semiconductor layer, an active layer, and a P-type semiconductor layer. The substrate provides the growth surface for the epitaxial material, the N-type semiconductor layer provides electrons for recombination and light emission, the P-type semiconductor layer provides holes for recombination and light emission, and the active layer is used for radiative recombination of electrons and holes to produce light emission.

[0004] However, due to the difference in lattice constant between the substrate (silicon carbide, sapphire, silicon wafer, etc.) and GaN, stress and defects accumulate during the growth of GaN-based epitaxial layers on the substrate. The stress release during the deposition process leads to the generation of dislocations, i.e., upward-extending leakage channels, which will affect the crystal growth quality of the bottom layer and quantum well region, and affect carrier transport and quantum efficiency.

[0005] In view of this, the inventors have specifically designed a semiconductor epitaxial structure and its fabrication method, as well as an LED chip, which leads to this invention. Summary of the Invention

[0006] The purpose of this invention is to provide a semiconductor epitaxial structure and its fabrication method, as well as an LED chip, to improve the crystal quality of the epitaxial layer and effectively provide charge carriers, thereby increasing the current spreading capability.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A semiconductor epitaxial structure, comprising:

[0009] Substrate;

[0010] A defect barrier layer, a first N-type semiconductor layer, a current blocking layer, a second N-type semiconductor layer, an active layer, and a P-type semiconductor layer are sequentially stacked on the surface of the substrate.

[0011] Preferably, the first N-type semiconductor layer includes a semiconductor layer with non-uniform n-type doping along a first direction, the first direction being perpendicular to the substrate and pointing from the substrate to the P-type semiconductor layer.

[0012] Preferably, if the semiconductor epitaxial structure is the epitaxial structure of a GaN-based light-emitting diode, then the second N-type semiconductor layer includes an n-type doped GaN layer, and the P-type semiconductor layer includes a p-type doped GaN layer.

[0013] Preferably, the defect barrier layer comprises an AlGaN film layer, used to block the upward extension of defects caused by lattice mismatch between the substrate and the semiconductor layer.

[0014] Preferably, the current blocking layer comprises an AlGaN layer for blocking the longitudinal transmission of current on the surface of the second N-type semiconductor layer.

[0015] Preferably, the Al composition of the defect barrier layer is greater than the Al composition of the current blocking layer.

[0016] Preferably, the n-type doping concentration of the first N-type semiconductor layer varies in a gradient along the first direction.

[0017] Preferably, the n-type doping concentration of the first N-type semiconductor layer is not less than 1*10⁻⁶. 17 cm -3 .

[0018] Preferably, the n-type doping concentration on both sides of the first N-type semiconductor layer is greater than the n-type doping concentration in other regions of the first N-type semiconductor layer.

[0019] Preferably, the n-type doping concentration on both sides of the first N-type semiconductor layer is obtained by linearly increasing or linearly decreasing.

[0020] Preferably, the n-type doping concentration on both sides of the first N-type semiconductor layer is 1*10⁻⁶. 19 cm -3 The n-type doping concentration in other regions of the first n-type semiconductor layer is 1*10. 18 cm -3 .

[0021] The present invention also provides a method for fabricating a semiconductor epitaxial structure, the method comprising the following steps:

[0022] Step S01: Provide a substrate;

[0023] Step S02: A defect barrier layer, a first N-type semiconductor layer, a current blocking layer, a second N-type semiconductor layer, an active layer, and a P-type semiconductor layer are sequentially grown on the surface of the substrate.

[0024] Wherein, the semiconductor epitaxial structure is the epitaxial structure of a GaN-based light-emitting diode, and the second N-type semiconductor layer includes an n-type doped GaN layer, and the P-type semiconductor layer includes a p-type doped GaN layer;

[0025] The defect barrier layer includes an AlGaN film;

[0026] The current blocking layer includes an AlGaN layer;

[0027] The first N-type semiconductor layer includes a semiconductor layer with non-uniform n-type doping along a first direction, the first direction being perpendicular to the substrate and pointing from the substrate to the P-type semiconductor layer; further, the n-type doping concentration on both sides of the first N-type semiconductor layer is greater than the n-type doping concentration in other regions of the first N-type semiconductor layer.

[0028] Preferably, the n-type doping concentration on both sides of the first N-type semiconductor layer is 1*10⁻⁶. 19 cm -3 The n-type doping concentration in other regions of the first n-type semiconductor layer is 1*10. 18 cm -3 .

[0029] Preferably, the Al composition of the defect barrier layer is greater than the Al composition of the current blocking layer.

[0030] The present invention also provides an LED chip, comprising:

[0031] The semiconductor epitaxial structure described in any of the above items;

[0032] An N-type electrode is formed in an ohmic contact with the N-type semiconductor layer;

[0033] The P-type electrode forms an ohmic contact with the P-type semiconductor layer.

[0034] As can be seen from the above technical solution, the semiconductor epitaxial structure provided by the present invention involves sequentially stacking a defect barrier layer, a first N-type semiconductor layer, a current blocking layer, a second N-type semiconductor layer, an active layer, and a P-type semiconductor layer on the surface of a substrate. The defect barrier layer blocks the upward extension of defects caused by lattice mismatch between the substrate and the semiconductor layers; simultaneously, the current blocking layer blocks the longitudinal transmission of current on the surface of the second N-type semiconductor layer, improving the lateral transmission of current at the interface and enhancing the current expansion effect.

[0035] Furthermore, the n-type doping concentration on both sides of the first N-type semiconductor layer is greater than the n-type doping concentration in other areas of the first N-type semiconductor layer. This allows the first N-type semiconductor layer to effectively provide charge carriers and increase current spreading capability while connecting the defect barrier layer and current blocking layer with high aluminum composition on both sides. It also has a better I / V curve under small current, thereby enabling the LED chip to have high internal quantum efficiency, which is especially suitable for small-size LED chips.

[0036] As can be seen from the above technical solutions, the method for fabricating semiconductor epitaxial structures provided by the present invention achieves the beneficial effects of the above-mentioned semiconductor epitaxial structures while being simple and convenient to manufacture and easy to mass-produce.

[0037] As can be seen from the above technical solutions, the LED chip provided by the present invention is obtained based on the above-mentioned semiconductor epitaxial structure. Therefore, it has the beneficial effects of the above-mentioned semiconductor epitaxial structure, while its manufacturing process is simple and convenient, and it is easy to mass-produce. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the semiconductor epitaxial structure provided in an embodiment of the present invention;

[0040] Figures 2 to 4 This is a schematic diagram illustrating the variation of the n-type doping concentration of the first N-type semiconductor layer with thickness, provided in an embodiment of the present invention.

[0041] Symbols in the diagram: 1. Substrate, 2. Buffer layer, 3. Unintentionally doped layer, 4. Defect barrier layer, 5. First N-type semiconductor layer, 6. Current blocking layer, 7. Second N-type semiconductor layer, 8. Active layer, 9. P-type semiconductor layer. Detailed Implementation

[0042] To make the content of this invention clearer, the following description, in conjunction with the accompanying drawings, further illustrates the invention. This invention is not limited to this specific embodiment. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0043] like Figure 1 As shown, a semiconductor epitaxial structure includes:

[0044] Substrate 1;

[0045] A buffer layer 2, an unintentionally doped layer 3, a defect barrier layer 4, a first N-type semiconductor layer 5, a current blocking layer 6, a second N-type semiconductor layer 7, an active layer 8, and a P-type semiconductor layer 9 are sequentially stacked on the surface of substrate 1.

[0046] It should be noted that, in this embodiment of the invention, in order to better achieve the crystal quality of the epitaxial structure, the buffer layer 2 and the unintentionally doped layer 3 may be selectively grown according to the actual situation, but this is not a limitation of the invention.

[0047] It is worth mentioning that the type of substrate 1 is not limited in the semiconductor epitaxial structure of this embodiment. For example, substrate 1 can be, but is not limited to, sapphire substrate 1, silicon substrate 1, etc. In addition, the specific material types of the second N-type semiconductor layer 7, active layer 8, and P-type semiconductor layer 9 are also not limited in the semiconductor epitaxial structure of this embodiment. For example, the second N-type semiconductor layer 7 can be, but is not limited to, a gallium nitride layer, and correspondingly, the P-type semiconductor layer 9 can be, but is not limited to, a gallium nitride layer.

[0048] In this embodiment of the invention, the first N-type semiconductor layer 5 includes a semiconductor layer with non-uniform n-type doping along a first direction, the first direction being perpendicular to the substrate 1 and pointing from the substrate 1 to the P-type semiconductor layer 9.

[0049] In this embodiment of the invention, the semiconductor epitaxial structure is used as the epitaxial structure of a GaN-based light-emitting diode. The second N-type semiconductor layer 7 includes an n-type doped GaN layer, and the P-type semiconductor layer 9 includes a p-type doped GaN layer.

[0050] In this embodiment of the invention, the defect barrier layer 4 further includes an AlGaN film layer, which is used to block the upward extension of defects caused by lattice mismatch between the substrate 1 and the semiconductor layer.

[0051] In this embodiment of the invention, the current blocking layer 6 further includes an AlGaN layer for blocking the longitudinal transmission of current on the surface of the second N-type semiconductor layer 7.

[0052] In this embodiment of the invention, the Al composition of the defect blocking layer 4 is greater than that of the current blocking layer 6.

[0053] In this embodiment of the invention, the n-type doping concentration of the first N-type semiconductor layer 5 further varies in a gradient along the first direction.

[0054] In this embodiment of the invention, the n-type doping concentration of the first N-type semiconductor layer 5 is further not less than 1*10⁻⁶. 17 cm -3 .

[0055] In this embodiment of the invention, the n-type doping concentration on both sides of the first N-type semiconductor layer 5 is greater than the n-type doping concentration in other regions of the first N-type semiconductor layer 5.

[0056] In this embodiment of the invention, the n-type doping concentration on both sides of the first N-type semiconductor layer 5 is further obtained by linearly increasing or linearly decreasing.

[0057] In this embodiment of the invention, the n-type doping concentration on both sides of the first N-type semiconductor layer 5 is further 1*10⁻⁶. 19 cm -3 The n-type doping concentration in other regions of the first n-type semiconductor layer 5 is 1*10. 18 cm -3 .

[0058] This invention also provides a method for fabricating a semiconductor epitaxial structure, the method comprising the following steps:

[0059] Step S01: Provide a substrate 1;

[0060] Step S02: Defect barrier layer 4, first N-type semiconductor layer 5, current blocking layer 6, second N-type semiconductor layer 7, active layer 8, and P-type semiconductor layer 9 are sequentially grown on the surface of substrate 1.

[0061] Wherein, the semiconductor epitaxial structure is used as the epitaxial structure of the GaN-based light-emitting diode, then the second N-type semiconductor layer 7 includes an n-type doped GaN layer, and the P-type semiconductor layer 9 includes a p-type doped GaN layer;

[0062] Defect barrier layer 4 includes an AlGaN film;

[0063] Current blocking layer 6 includes an AlGaN layer;

[0064] The first N-type semiconductor layer 5 includes a semiconductor layer with non-uniform n-type doping along a first direction, which is perpendicular to the substrate 1 and points from the substrate 1 to the P-type semiconductor layer 9; further, the n-type doping concentration on both sides of the first N-type semiconductor layer 5 is greater than the n-type doping concentration in other regions of the first N-type semiconductor layer 5.

[0065] Furthermore, the Al composition of the defect barrier layer 4 is greater than that of the current blocking layer 6.

[0066] In this embodiment of the invention, the n-type doping concentration on both sides of the first N-type semiconductor layer 5 is further 1*10⁻⁶. 19 cm -3 The n-type doping concentration in other regions of the first n-type semiconductor layer 5 is 1*10. 18 cm -3.

[0067] Figures 2 to 4 The diagram shows the variation of n-type doping concentration with thickness of the first N-type semiconductor layer 5 provided in an embodiment of the present invention, where the horizontal axis represents thickness and the vertical axis represents n-type doping concentration. This embodiment preferably shows... Figure 2 The doping gradient shown is as follows; it should be noted that... Figure 2-4 This is merely an example and is not intended to limit the scope of the invention.

[0068] This invention also provides an LED chip, comprising:

[0069] Semiconductor epitaxial structure of any of the above;

[0070] The N-type electrode forms an ohmic contact with the N-type semiconductor layer;

[0071] The P-type electrode forms an ohmic contact with the P-type semiconductor layer 9.

[0072] As can be seen from the above technical solution, the semiconductor epitaxial structure provided by the present invention involves sequentially stacking a defect barrier layer 4, a first N-type semiconductor layer 5, a current blocking layer 6, a second N-type semiconductor layer 7, an active layer 8, and a P-type semiconductor layer 9 on the surface of a substrate 1. The defect barrier layer 4 blocks the upward extension of defects caused by lattice mismatch between the substrate 1 and the semiconductor layer; simultaneously, the current blocking layer 6 blocks the longitudinal transmission of current on the surface of the second N-type semiconductor layer 7, improving the lateral transmission of current at the interface and enhancing the current expansion effect.

[0073] Furthermore, the n-type doping concentration on both sides of the first N-type semiconductor layer 5 is greater than the n-type doping concentration in other areas of the first N-type semiconductor layer 5. This allows the first N-type semiconductor layer 5 to effectively provide charge carriers and increase current spreading capability while connecting the defect barrier layer 4 and the current blocking layer 6 with high aluminum composition on both sides. It also allows it to have a better I / V curve under small current, thereby enabling the LED chip to have higher internal quantum efficiency, which is especially suitable for small-size LED chips.

[0074] As can be seen from the above technical solutions, the method for fabricating semiconductor epitaxial structures provided by the present invention achieves the beneficial effects of the above-mentioned semiconductor epitaxial structures while being simple and convenient to manufacture and easy to mass-produce.

[0075] As can be seen from the above technical solutions, the LED chip provided by the present invention is obtained based on the above-mentioned semiconductor epitaxial structure. Therefore, it has the beneficial effects of the above-mentioned semiconductor epitaxial structure, while its manufacturing process is simple and convenient, and it is easy to mass-produce.

[0076] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0077] It should also be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes the aforementioned element.

[0078] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A semiconductor epitaxial structure, characterized in that, include: Substrate; A defect barrier layer, a first N-type semiconductor layer, a current blocking layer, a second N-type semiconductor layer, an active layer, and a P-type semiconductor layer are sequentially stacked on the surface of the substrate. Wherein, the first N-type semiconductor layer includes a semiconductor layer with non-uniform n-type doping along a first direction, the first direction being perpendicular to the substrate and pointing from the substrate to the P-type semiconductor layer; If the semiconductor epitaxial structure is used as the epitaxial structure of a GaN-based light-emitting diode, then the second N-type semiconductor layer includes an n-type doped GaN layer, and the P-type semiconductor layer includes a p-type doped GaN layer. The Al composition of the defect barrier layer is greater than that of the current blocking layer; The n-type doping concentration on both sides of the first N-type semiconductor layer is greater than the n-type doping concentration in other areas of the first N-type semiconductor layer.

2. The semiconductor epitaxial structure according to claim 1, characterized in that, The defect barrier layer includes an AlGaN film layer, which is used to block the upward extension of defects caused by lattice mismatch between the substrate and the semiconductor layer.

3. The semiconductor epitaxial structure according to claim 1, characterized in that, The current blocking layer includes an AlGaN layer for blocking the longitudinal transmission of current on the surface of the second N-type semiconductor layer.

4. The semiconductor epitaxial structure according to claim 1, characterized in that, The n-type doping concentration of the first N-type semiconductor layer varies in a gradient along the first direction.

5. The semiconductor epitaxial structure according to claim 4, characterized in that, The n-type doping concentration of the first N-type semiconductor layer is not less than 1*10 17 cm -3 .

6. The semiconductor epitaxial structure according to claim 1, characterized in that, The n-type doping concentration on both sides of the first N-type semiconductor layer is obtained by linearly increasing or linearly decreasing.

7. A method for fabricating a semiconductor epitaxial structure, characterized in that, The manufacturing method includes the following steps: Step S01: Provide a substrate; Step S02: A defect barrier layer, a first N-type semiconductor layer, a current blocking layer, a second N-type semiconductor layer, an active layer, and a P-type semiconductor layer are sequentially grown on the surface of the substrate. Wherein, the semiconductor epitaxial structure is the epitaxial structure of a GaN-based light-emitting diode, and the second N-type semiconductor layer includes an n-type doped GaN layer, and the P-type semiconductor layer includes a p-type doped GaN layer; The defect barrier layer includes an AlGaN film; The current blocking layer includes an AlGaN layer; The first N-type semiconductor layer includes a semiconductor layer with non-uniform n-type doping along a first direction, the first direction being perpendicular to the substrate and pointing from the substrate to the P-type semiconductor layer; the n-type doping concentration on both sides of the first N-type semiconductor layer is greater than the n-type doping concentration in other regions of the first N-type semiconductor layer.

8. An LED chip, characterized in that, include; The semiconductor epitaxial structure according to any one of claims 1-6; An N-type electrode is formed in an ohmic contact with the N-type semiconductor layer; The P-type electrode forms an ohmic contact with the P-type semiconductor layer.

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