Deep ultraviolet light emitting diode and preparation method thereof

Abstract

The invention relates to a deep ultraviolet light-emitting diode and a preparation method thereof. The deep ultraviolet light-emitting diode sequentially comprises a substrate, a buffer layer, an n-type doped AlGaN layer, a multi-quantum well active layer, a first AlN insertion layer, a p-type electron blocking layer, a second AlN insertion layer, a p-type doped AlGaN layer and a p-type contact layer from bottom to top. Compared with a traditional AlGaN-based p-EBL structure, the structure that the thin AlN layers are inserted into the two sides of the p-EBL has the advantages that piezoelectric polarization is restrained to a low level, and the spontaneous polarization effect is reduced. In addition, the AlN insertion layer also improves the hole injection efficiency through in-band tunneling, and reduces the leakage of electrons in the active region to the p-type layer at the same time. The external quantum efficiency and the radiative recombination rate are remarkably improved, the photoelectric property of the AlGaN-based deep ultraviolet light-emitting diode is enhanced, and the rapid reduction of the efficiency attenuation effect is also inhibited.

Description

Technical Field

[0001] The invention belongs to the technical field of LED semiconductors, and in particular relates to a deep ultraviolet light emitting diode and a preparation method thereof. Background Art

[0002] With the rapid development of LED technology, the luminous band of LED from green light to ultraviolet light has been widely used in commercial products. In recent years, the broad application prospects of short-wavelength deep ultraviolet LEDs have been continuously explored, attracting many people to shift their research focus to it, and it has also become a new hot spot for research and investment in the global industry. Deep ultraviolet LEDs are widely used in white light solid-state lighting, optical storage, ink printing, water and air purification, biomedicine, environmental protection and other fields. Due to its small size, simple structure, high speed, adjustable wavelength, high energy, long service life, energy saving, and green environmental protection, deep ultraviolet LEDs have many advantages over ultraviolet mercury lamps. It is very likely to replace the existing mercury lamps and become the next generation of ultraviolet light sources, with huge social and economic value. After more than ten years of development, although AlGaN-based deep ultraviolet light-emitting diodes have made some progress in epitaxial growth, the external quantum efficiency of AlGaN-based deep ultraviolet light-emitting diodes is still less than 10%, which limits the large-scale commercial application of AlGaN-based deep ultraviolet light-emitting diodes.

[0003] Due to the high Al content of deep ultraviolet light-emitting diodes, high Al content AlGaN materials have a very strong polarization effect. This polarization will form a very strong polarization electric field in the semiconductor, thus affecting the electrical properties of the material. As the Al content increases, the polarization effect of the device is further enhanced. The electric field generated by this polarization effect will lead to the quantum confined Stark effect. The polarization electric field causes the conduction band and valence band of the semiconductor to bend and deform, resulting in a decrease in the overlap rate of the electron and hole wave functions, which in turn reduces the radiation recombination efficiency of the device and reduces the luminous efficiency.

[0004] In the multi-quantum well region, the existence of piezoelectric polarization and spontaneous polarization effects leads to band bending, resulting in serious electron leakage problems, resulting in relatively low output light power. In order to suppress electron leakage, AlGaN-based deep ultraviolet light-emitting diodes usually epitaxially grow a p-type electron blocking layer with a high Al component above the active region. The use of the electron blocking layer will induce the generation of positive interface charges between the electron blocking layer and the last quantum barrier through polarization. The presence of positive interface charges will attract electrons to accumulate in the potential well at the junction of the last quantum barrier and the electron blocking layer, thereby increasing the probability of electron leakage; in addition, the positive interface charges will also block holes from the p-type injection region, reducing the hole concentration in the electron blocking layer, thereby reducing the hole injection efficiency. Therefore, the p-type electron blocking layer cannot completely prevent the leakage of electrons. As the driving current increases, the leakage phenomenon of the deep ultraviolet light-emitting diode will become more and more serious, resulting in serious efficiency decay of the deep ultraviolet light-emitting diode. In order to enhance the electron blocking ability of the p-type electron blocking layer, it is necessary to design and optimize the p-type electron blocking layer to reduce electron overflow. At the same time, promoting the transmission of holes to the active layer also helps to suppress electron leakage.

[0005] Therefore, in order to achieve effective carrier injection, reduce electron leakage and promote the transfer of holes to the active layer, it is necessary to design a structure that can effectively regulate the interface barrier height between the EBL and the hole injection layer. This structure can solve the problems of low carrier injection efficiency and serious efficiency degradation of deep ultraviolet LEDs, and provide more possibilities for the industrialization of deep ultraviolet LEDs. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides an AlGaN-based deep ultraviolet light-emitting diode and a preparation method. We proposed a new structure, that is, embedding thin AlN insertion layers on both sides of the p-type electron blocking layer. By introducing the thin AlN insertion layer, we successfully reduced the polarization effect and effectively suppressed the leakage of electrons, so that more electrons can be effectively retained in the active area, thereby increasing the electron concentration in the active area. The embedding of the AlN thin layer can also produce an intra-band tunneling effect, thereby promoting the transmission of holes to the multi-quantum well active area. When holes are transmitted in the p-EBL layer, these holes will encounter a potential barrier at the AlN insertion layer. Due to the existence of the intra-band tunneling effect, the holes can "cross" this potential barrier with a higher probability, thereby entering the quantum well layer more smoothly. This intra-band tunneling effect improves the transmission efficiency of holes, allowing more holes to reach the quantum well layer and undergo radiative recombination with electrons.

[0007] As the hole transport efficiency increases, the hole concentration in the quantum well layer also increases accordingly. This means that in the quantum well layer, more holes and electrons undergo radiative recombination. This increase in the concentration of holes and electrons in the quantum well directly leads to a significant increase in the radiative recombination efficiency of the quantum well layer. At the same time, since more carriers are effectively used in the radiative recombination process rather than ineffective leakage or recombination, the efficiency drop of the LED is also significantly suppressed.

[0008] The technical solution of the present invention is as follows:

[0009] A deep ultraviolet light-emitting diode includes a substrate, characterized in that the deep ultraviolet light-emitting diode also includes a buffer layer, an electron injection layer, a multi-quantum well active region, a first AlN insertion layer, a p-type doped electron blocking layer, a second AlN insertion layer, a hole injection layer, and a p-type contact layer arranged on the substrate from bottom to top.

[0010] Preferably, the thickness of the first AlN insertion layer is 0.5-5 nm; the thickness of the second AlN insertion layer is 0.5-5 nm.

[0011] Preferably, the first AlN insertion layer and the second AlN insertion layer are both undoped, p-type doped or n-type doped.

[0012] Preferably, the material of the substrate is one of sapphire, silicon carbide (SiC), aluminum nitride (AlN), gallium nitride (GaN) or silicon (Si);

[0013] The material of the buffer layer is Al x1 Ga 1-x1 N, where 0≤x1≤1.

[0014] Preferably, the multi-quantum well active region is Al2O3 grown alternately in layers from bottom to top. x4 Ga 1-x4 N potential well layer and Al x3 Ga 1-x3 N barrier layer, where 0≤x4≤1, 0≤x3≤1, x3>x4, and the top layer of the multi-quantum well active region is Al x3 Ga 1-x3 N barrier layer; in a single cycle, Al x3 Ga 1-x3 The thickness of the N barrier layer is 5nm-15nm, and the Al x4 Ga 1-x4 The thickness of the N potential well layer is 2nm-5nm.

[0015] Preferably, the material of the p-type doped electron blocking layer is Al x5 Ga 1-x5N, where 0≤x5≤1, and its thickness is 10nm-100nm; the p-type doped electron blocking layer is doped with Mg impurities, and the doping concentration is 1e17cm -3 -5e20 cm -3 .

[0016] Preferably, the hole injection layer is made of p-type doped Al x6 Ga 1-x6 N, where 0≤x6≤1, and its thickness is 10nm-500nm; the hole injection layer is doped with Mg impurities, and the doping concentration is 1e17 cm -3 -5e20cm -3 .

[0017] Preferably, the material of the p-type contact layer is Al x7 Ga 1-x7 N, wherein 0≤x7≤1; the p-type contact layer is doped with Mg impurities and has a thickness of 1nm-50nm.

[0018] Preferably, the material of the electron injection layer is n-Al x2 Ga 1-x2 N, where the Al component ranges from 0≤x2≤1, and Si impurity is used for doping, with a doping concentration of 1e17 cm -3 -5e20 cm -3 ; The thickness of the electron injection layer is 0.1μm-4μm.

[0019] A method for preparing a deep ultraviolet light-emitting diode, characterized in that the preparation method comprises the following steps:

[0020] S1: prepare substrate;

[0021] S2: epitaxially growing a buffer layer on the substrate;

[0022] S3: growing an electron injection layer on the buffer layer and performing N-type doping;

[0023] S4: growing a multi-quantum well active region on the electron injection layer, the last layer of the active region being an Alx3Ga1-x3N quantum barrier layer, 0≤x3≤1;

[0024] S5: growing a first AlN insertion layer on the multi-quantum well active region;

[0025] S6: growing an electron blocking layer on the surface of the first AlN insertion layer and performing P-type doping;

[0026] S7: growing a second AlN insertion layer on the electron blocking layer;

[0027] S8: A hole injection layer and a contact layer are sequentially grown on the second AlN insertion layer to perform P-type doping.

[0028] The beneficial effects of the present invention are:

[0029] The present invention cleverly introduces an ultra-thin aluminum nitride (AlN) layer into the epitaxial structure of a traditional deep ultraviolet LED to construct a new AlN / p-EBL / AlN structure to enhance the carrier injection efficiency and radiation recombination efficiency. This innovation opens up a new path for improving the performance of LEDs.

[0030] The introduction of this ultra-thin AlN insertion layer has a significant regulatory effect on the transport behavior of holes in the electron blocking layer (EBL). Through the carefully designed AlN layer, holes can be locally aggregated in the insertion layer by means of thermal ion emission and quantum tunneling. This local aggregation not only helps to reduce the effective barrier height of holes at the EBL, but also can significantly improve the injection efficiency of holes. With the improvement of hole injection efficiency, the hole concentration in the electron blocking layer also increases, thereby reducing the barrier height of the electron blocking layer to holes, allowing more holes to enter the active area smoothly.

[0031] After adopting the AlN / p-EBL / AlN structure, not only the hole injection efficiency is improved, but also the electron concentration in the active region shows a significant increase. This shows that the addition of the ultra-thin AlN layer not only regulates the transport behavior of holes, but also improves the blocking ability of EBL to electrons. This improvement allows more electrons to be effectively bound in the multi-quantum well active region structure, further improving the performance of deep ultraviolet light-emitting diodes.

[0032] In summary, the use of AlN / p-EBL / AlN structure has multiple advantages. First, it can effectively limit the overflow of electrons. Second, it reduces the barrier to holes and promotes the injection of holes into the quantum well layer. This two-way optimization significantly improves the radiative recombination rate in the active region and reduces the Auger recombination of carriers, thereby improving the overall luminous efficiency and output power of AlGaN-based deep ultraviolet light-emitting diodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of the epitaxial structure of the AlGaN-based deep ultraviolet LED in Example 1 of the present invention, substrate 101, buffer layer 102, n-type doped AlGaN layer 103, the n-type doped AlGaN layer 103 includes a multi-quantum well active layer 104, a first AlN insertion layer 105, a p-type electron blocking layer 106, a second AlN insertion layer 107, a p-type doped AlGaN layer 108, and a p-type contact layer 109 in sequence.

[0034] Figure 2 Schematic diagram of a standard deep ultraviolet light-emitting diode epitaxial structure, substrate 201, buffer layer 202, n-type doped AlGaN layer 203, multi-quantum well active layer 204, p-type electron blocking layer 205, p-type doped AlGaN layer 206, p-type contact layer 207 above the n-type doped AlGaN layer 203 in sequence.

[0035] Figure 3 This is a relationship diagram between the light power and current density of a standard deep ultraviolet light emitting diode and the deep ultraviolet light emitting diode embodiment 1 proposed by the present invention.

[0036] Figure 4 The distribution diagram of the electron concentration in the active layer of the standard deep ultraviolet light emitting diode and the deep ultraviolet light emitting diode embodiment 1 proposed by the present invention.

[0037] Figure 5 The distribution diagram of hole concentration in the active layer of a standard deep ultraviolet light emitting diode and the deep ultraviolet light emitting diode embodiment 1 proposed by the present invention.

[0038] Figure 6 This is a relationship diagram between the external quantum efficiency and current density of a standard deep ultraviolet light emitting diode and the deep ultraviolet light emitting diode embodiment 1 proposed in the present invention.

[0039] FIG. 7( a ) is a graph showing the relationship between the optical power and the current density of the deep ultraviolet light emitting diode embodiment 2 proposed by the present invention.

[0040] FIG. 7( b ) is a graph showing the relationship between the external quantum efficiency and the current density of the deep ultraviolet light-emitting diode embodiment 2 proposed by the present invention.

[0041] FIG8( a ) is a graph showing the relationship between the optical power and the current density of the deep ultraviolet light emitting diode embodiments 3 and 4 proposed by the present invention.

[0042] FIG8( b ) is a graph showing the relationship between the external quantum efficiency and the current density of the deep ultraviolet light-emitting diodes of Embodiments 3 and 4 proposed in the present invention. DETAILED DESCRIPTION

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention. The experimental methods described in the following embodiments are all conventional methods unless otherwise specified; the reagents and materials, unless otherwise specified, can be obtained from public commercial channels.

[0044] Spatially relative terms such as "below," "beneath," "below," "above," "upper," etc. are used in this specification to explain the positioning of one element relative to a second element. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures.

[0045] In addition, the use of terms such as "first", "second", etc. to describe various elements, layers, regions, sections, etc. is not intended to be limiting. The use of "having", "containing", "including", "comprising", etc. is open-ended, indicating the presence of the stated elements or features, but does not exclude additional elements or features. Unless the context clearly states otherwise.

[0046] like Figure 1 As shown, the AlGaN-based deep ultraviolet light-emitting diode described in the present invention includes a substrate 101, a buffer layer 102, an electron injection layer 103, a multi-quantum well active region 104, a first insertion layer 105, a p-type doped electron blocking layer 106, a second insertion layer 107, a hole injection layer 108, and a p-type contact layer 109, which are arranged in sequence from bottom to top.

[0047] The material of the substrate 101 is one of sapphire, silicon carbide (SiC), aluminum nitride (AlN), gallium nitride (GaN) or silicon (Si).

[0048] The material of the buffer layer 102 is Al x1 Ga 1-x1 N, where 0≤x1≤1.

[0049] The electron injection layer 103 is made of n-Al x2 Ga 1-x2 N, where the value range of Al component x2 is 0≤x2≤1, and Si impurity is used for doping with a doping concentration of 1e17 cm -3 -5e20 cm -3 The thickness of the electron injection layer 103 is 0.1 μm-4 μm.

[0050] The multi-quantum well active region 104 is Al2O3 grown alternately in layers from bottom to top. x4 Ga 1-x4 N potential well layer and Al x3 Ga 1-x3 N barrier layer, the top layer of the multi-quantum well active region is Al x3 Ga 1-x3 N barrier layer, wherein 0≤x4≤1, 0≤x3≤1, x3>x4; wherein the Al x3 Ga 1-x3 The thickness of the N barrier layer is 5nm-15nm, and the Al x4 Ga 1-x4The thickness of the N potential well layer is 2nm-5nm.

[0051] The material of the first insertion layer 105 is AlN, and its thickness ranges from 0.5 to 5 nm. The material of the second insertion layer 107 is AlN, and its thickness ranges from 0.5 to 5 nm. The first AlN insertion layer and the second AlN insertion layer can be undoped, p-type doped or n-type doped at the same time.

[0052] The material of the p-type electron blocking layer 106 is Al x5 Ga 1-x5 N, where 0≤x5≤1, its thickness is 10nm-100nm, and the p-type doped electron blocking layer is doped with Mg impurities with a doping concentration of 1e17cm -3 -5e20 cm -3 .

[0053] The material of the hole injection layer 108 is p-type doped Al x6 Ga 1-x6 N, where 0≤x6≤1, and its thickness is 10nm-500nm; the hole injection layer 108 is doped with Mg impurities, and the doping concentration is 1e17cm -3 -5e20 cm -3 .

[0054] The material of the p-type contact layer 109 is p-GaN or Al x7 Ga 1-x7 N, wherein 0≤x7≤1, and the thickness of the p-type contact layer 109 is 1 nm-50 nm.

[0055] A method for preparing an AlGaN-based deep ultraviolet light-emitting diode comprises the following steps:

[0056] preparing a substrate;

[0057] The metal organic chemical vapor deposition (MOCVD) process is used to grow each material layer. First, Al is grown on the substrate. x1 Ga 1-x1 N buffer layer, and nitridation treatment is performed on the substrate on which the buffer layer has been deposited. Specifically, the substrate on which the buffer layer has been deposited is transferred into MOCVD, and pre-treated in a hydrogen atmosphere for 1 to 10 minutes at a treatment temperature of 1000°C-1200°C.

[0058] Next, n-Al is grown on the buffer layer. x2 Ga 1-x2 The electron injection layer of N has an Al component x2 value range of 0≤x2≤1, a growth temperature of the electron injection layer of 1000℃-1200℃, Si impurity doping, a thickness of 0.1μm-4μm, and a doping concentration of 1e17 cm-3 -5e20 cm -3 ;

[0059] Then, a multi-quantum well active layer is grown on the electron injection layer at a certain period, specifically, a certain period of alternately grown Al x3 Ga 1-x3 N barrier layer and Al x4 Ga 1-x4 N potential well layer, and finally Al x4 Ga 1-x4 The last Al layer is grown on the N well layer x3 Ga 1-x3 N quantum barrier layers, 0≤x3≤1, 0≤x4≤1.

[0060] Next, in the last layer of Al x3 Ga 1-x3 A first AlN insertion layer is grown on the N quantum barrier layer, and its thickness is 0.5 to 5 nm;

[0061] An AlGaN electron blocking layer is then grown on the surface of the first AlN insertion layer. The growth temperature of the electron blocking layer is 900° C.-1200° C. The thickness of the AlGaN electron blocking layer is 10 nm-100 nm. Mg impurities are used for p-type doping, and the doping concentration is 1e17 cm -3 -5e20 cm -3 ;

[0062] Continue to grow a second AlN insertion layer on the AlGaN electron blocking layer, with a thickness of 0.5 to 5 nm;

[0063] Growing p-type Al on the second AlN insertion layer x6 Ga 1-x6 N hole injection layer, 0≤x6≤1, growth temperature is 900℃-1200℃, and Mg impurities are introduced for P-type doping, and p-type Al is grown on the hole injection layer x7 Ga 1-x7 N contact layer, growth temperature is 900℃-1200℃, and Mg impurities are introduced for P-type doping, 0≤x7≤1, and the doping concentration is 1e17 cm -3 -5e20 cm -3 , the thickness of the hole injection layer is 10nm-500nm.

[0064] The present invention skillfully introduces an ultra-thin aluminum nitride (AlN) layer into the epitaxial structure of a conventional deep ultraviolet LED to construct a novel AlN / p-EBL / AlN structure to enhance the carrier injection efficiency and radiation recombination efficiency. The beneficial effects of the present invention are described below through specific embodiments.

[0065] Example 1

[0066] The AlGaN-based deep ultraviolet light-emitting diode described in embodiment 1 of the present invention is as follows: Figure 1 As shown, the entire epitaxial process is completed by using MOCVD (metal organic chemical vapor deposition) technology. On the surface of the substrate along the epitaxial growth direction, a substrate 101, a buffer layer 102, an n-type doped AlGaN electron injection layer 103 are sequentially arranged, and one side of the n-type doped AlGaN electron injection layer 103 includes a multi-quantum well active region 104, a first AlN insertion layer 105, a p-type electron blocking layer 106, a second AlN insertion layer 107, a p-type doped AlGaN hole injection layer 108, and a p-type contact layer 109.

[0067] In this embodiment 1, the material of the substrate 101 is sapphire, an AlN buffer layer 102 with a thickness of 100 nm is grown on the sapphire substrate, and a nitridation treatment is performed on the sapphire substrate on which the AlN buffer layer 102 has been deposited. Specifically, the AlN buffer layer is pretreated in a hydrogen atmosphere in an MOCVD chamber for 1 to 10 minutes at a treatment temperature of 1000° C. to 1200° C., and then a nitridation treatment is performed to improve the crystal quality of the AlN buffer layer 102, and the crystal quality of the subsequently deposited AlN epitaxial layer can be effectively improved.

[0068] Next, an n-type doped AlGaN electron injection layer 103 is epitaxially grown on the AlN buffer layer 102 at 1000-1100°C, wherein the Al component is selected to be 0.6, and Si impurities are introduced for N-type doping, and the doping concentration is 8e18cm -3 , thickness is 4μm.

[0069] The material of the multi-quantum well active region 104 is a potential well layer Al2O3 that is alternately grown from bottom to top. 0.45 Ga 0.55 N and barrier layer Al 0.57 Ga 0.43 N is five periodically alternately stacked potential well layers and potential barrier layers, the growth temperature is controlled in the range of 1000-1100° C., the thickness of the potential well layer is 3 nm, and the thickness of the potential barrier layer is 10 nm.

[0070] Next, an undoped first AlN insertion layer 105, a p-type electron blocking layer 106, and an undoped second AlN insertion layer 107 are grown on the multi-quantum well active region. The thickness of the first AlN insertion layer 105 is 1 nm. The material of the p-type electron blocking layer 106 is p-Al 0.6 Ga 0.4 N, the growth temperature is controlled within 1000-1100℃, and the doping concentration is 2e19cm -3, its thickness is 10 nm, and the thickness of the undoped second AlN insertion layer 107 is 1 nm.

[0071] Then, a p-type AlGaN hole injection layer 108 is grown on the second AlN insertion layer 107. 0.4 Ga 0.6 N, growth temperature is 1000-1100℃, doping concentration is 4e19cm -3 , thickness is 50nm.

[0072] The material of the p-type contact layer 109 is p-GaN, the growth temperature is 1000-1100°C, and the doping concentration is 1e20cm -3 , thickness is 50nm.

[0073] For those skilled in the art, it is obvious that the specific selection of Al source, Ga source and N source in the present invention is not limited. In the specific embodiment of the present invention, we selected trimethylaluminum as the Al source required in the epitaxial growth process. Trimethylaluminum is a widely used organic aluminum compound with stable chemical properties and easy to decompose in the vapor phase epitaxy process, providing ideal conditions for growing high-quality AlGaN layers. For the selection of Ga source, we used trimethylgallium. Trimethylgallium is also a commonly used organic gallium compound with good volatility and thermal stability in the vapor phase epitaxy process, ensuring the uniform distribution of Ga elements during the growth process. In terms of doping, we used silane and magnesium as N-type and P-type doping respectively. Silane, as a common N-type dopant, can effectively improve the conductivity of the material; while magnesium, as a P-type dopant, can introduce holes and enhance the luminescence performance of the material. Hydrogen is used as a carrier gas and ammonia is used as a nitrogen source to provide sufficient nitrogen elements for the growth of AlGaN layers.

[0074] It should be emphasized that the above process parameters and material selection are only one of the preferred embodiments of the present invention. For those skilled in the art, they can make appropriate improvements and substitutions to the process parameters and material selections based on their own practical experience and technical requirements without departing from the technical principles of the present invention. These improvements and substitutions may include but are not limited to: changing process parameters such as device growth temperature and pressure, or selecting other suitable dopants. These changes should be considered within the scope of protection of the present invention.

[0075] Figure 3 Graph showing the relationship between the optical power and current density of a standard deep ultraviolet light emitting diode and the deep ultraviolet light emitting diode embodiment 1 proposed by the present invention. Figure 3 It can be seen that the optical power of the deep ultraviolet light emitting diode proposed in the present invention is significantly improved compared with the standard deep ultraviolet light emitting diode.

[0076] Figure 4 The distribution diagram of the electron concentration in the active layer of the standard deep ultraviolet light emitting diode and the deep ultraviolet light emitting diode embodiment 1 proposed by the present invention. Figure 4 It can be seen that, compared with the standard deep ultraviolet light-emitting diode, the electron concentration in the active region of the deep ultraviolet light-emitting diode proposed by the present invention is significantly increased.

[0077] Figure 5 The distribution diagram of hole concentration in the active layer of a standard deep ultraviolet light emitting diode and the deep ultraviolet light emitting diode embodiment 1 proposed by the present invention. Figure 5 It can be seen that, compared with the standard deep ultraviolet light-emitting diode, the hole concentration in the active region of the deep ultraviolet light-emitting diode proposed by the present invention is significantly increased.

[0078] Figure 6 The figure is a relationship diagram between the external quantum efficiency and the current density of a standard deep ultraviolet light emitting diode and the deep ultraviolet light emitting diode of Example 1 proposed by the present invention. Figure 6 It can be seen from the figure that the external quantum efficiency of the deep ultraviolet light-emitting diode proposed in the present invention (current density is 120A / cm 2 Under the conditions of , it is improved by 64.5% compared with the standard deep ultraviolet diode, and the efficiency decay effect is also improved.

[0079] Example 2

[0080] This embodiment 2 provides an AlGaN-based deep ultraviolet light-emitting diode. The structure of the AlGaN-based deep ultraviolet light-emitting diode described in this embodiment 2 is basically the same as the AlGaN-based deep ultraviolet light-emitting diode structure shown in embodiment 1, except that: the AlN first insertion layer 105 and the AlN second insertion layer 107 are p-type doped with a doping concentration of 2e19cm -3 .

[0081] FIG. 7( a ) is a graph showing the relationship between the optical power and the current density of the specific embodiment 2 of the deep ultraviolet light emitting diode proposed by the present invention.

[0082] FIG. 7( b ) is a graph showing the relationship between the external quantum efficiency and the current density of the specific embodiment 2 of the deep ultraviolet light-emitting diode proposed by the present invention.

[0083] Example 3

[0084] This embodiment 3 provides an AlGaN-based deep ultraviolet light-emitting diode. The structure of the AlGaN-based deep ultraviolet light-emitting diode described in this embodiment 3 is basically the same as the AlGaN-based deep ultraviolet light-emitting diode structure shown in Example 1, except that the thickness of the first AlN insertion layer 105 is 0.5nm, and the thickness of the second AlN insertion layer 107 is 1nm.

[0085] Example 4

[0086] This embodiment 4 provides an AlGaN-based deep ultraviolet light-emitting diode. The structure of the AlGaN-based deep ultraviolet light-emitting diode described in this embodiment 4 is basically the same as the structure of the AlGaN-based deep ultraviolet light-emitting diode shown in embodiment 1, except that: the barrier layer is Al 0.5 Ga 0.5 N, the material of the p-type electron blocking layer 106 is p-Al 0.85 Ga 0.15 N, the thickness of the AlN first insertion layer 105 and the AlN second insertion layer 107 are both 2 nm.

[0087] FIG8( a ) is a graph showing the relationship between the optical power and the current density of the deep ultraviolet light emitting diodes of Embodiments 3 and 4 proposed by the present invention.

[0088] FIG8( b ) is a graph showing the relationship between the external quantum efficiency and the current density of the deep ultraviolet light-emitting diodes of Examples 3 and 4 proposed by the present invention.

[0089] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A deep ultraviolet light-emitting diode, comprising a substrate, characterized in that: The deep ultraviolet light-emitting diode also includes a buffer layer, an electron injection layer, a multi-quantum well active region, a first AlN insertion layer, a p-type doped electron blocking layer, a second AlN insertion layer, a hole injection layer, and a p-type contact layer which are sequentially arranged on the substrate from bottom to top.

2. The deep ultraviolet light emitting diode according to claim 1, characterized in that: The thickness of the first AlN insertion layer is 0.5-5 nm; the thickness of the second AlN insertion layer is 0.5-5 nm.

3. The deep ultraviolet light emitting diode according to claim 2, characterized in that: The first AlN insertion layer and the second AlN insertion layer are both undoped, p-type doped or n-type doped.

4. The deep ultraviolet light emitting diode according to claim 1, characterized in that: The material of the substrate is one of sapphire, silicon carbide (SiC), aluminum nitride (AlN), gallium nitride (GaN) or silicon (Si); The material of the buffer layer is Al x1 Ga 1-x1 N, where 0≤x1≤1.

5. The deep ultraviolet light emitting diode according to claim 1, characterized in that: The multi-quantum well active region is Al2O3 grown alternately in layers from bottom to top. x4 Ga 1-x4 N potential well layer and Al x3 Ga 1-x3 N barrier layer, wherein 0≤x4≤1, 0≤x3≤1, x3>x4, the topmost layer of the multi-quantum well active region is Al x3 Ga 1-x3 N barrier layer; in a single cycle, the Al x3 Ga 1-x3 The thickness of the N barrier layer is 5nm-15nm, and the Al x4 Ga 1-x4 The thickness of the N potential well layer is 2nm-5nm.

6. The deep ultraviolet light emitting diode according to claim 1, characterized in that: The material of the p-type doped electron blocking layer is Al x5 Ga 1-x5 N, where 0≤x5≤1, and its thickness is 10nm-100nm; the p-type doped electron blocking layer is doped with Mg impurities, and the doping concentration is 1e17 cm -3 -5e20 cm -3 .

7. The deep ultraviolet light emitting diode according to claim 1, characterized in that: The hole injection layer is made of p-type doped Al x6 Ga 1-x6 N, where 0≤x6≤1, and its thickness is 10nm-500nm; the hole injection layer is doped with Mg impurities, and the doping concentration is 1e17 cm -3 -5e20 cm -3 .

8. The deep ultraviolet light emitting diode according to claim 1, characterized in that: The material of the p-type contact layer is Al x7 Ga 1-x7 N, wherein 0≤x7≤1; the p-type contact layer is doped with Mg impurities and has a thickness of 1nm-50nm.

9. The deep ultraviolet light emitting diode according to claim 1, characterized in that: The material of the electron injection layer is n-Al x2 Ga 1-x2 N, where the Al component ranges from 0≤x2≤1, and Si impurity is used for doping, with a doping concentration of 1e17 cm -3 -5e20 cm -3 ; The thickness of the electron injection layer is 0.1μm-4μm.

10. A method for preparing a deep ultraviolet light-emitting diode according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: S1: prepare substrate; S2: epitaxially growing a buffer layer on the substrate; S3: growing an electron injection layer on the buffer layer and performing N-type doping; S4: growing a multi-quantum well active region on the electron injection layer, the last layer of the active region being Al x3 Ga 1-x3 N quantum barrier layers, 0≤x3≤1; S5: growing a first AlN insertion layer on the multi-quantum well active region; S6: growing an electron blocking layer on the surface of the first AlN insertion layer and performing P-type doping; S7: growing a second AlN insertion layer on the electron blocking layer; S8: sequentially growing a hole injection layer and a contact layer on the second AlN insertion layer, and performing P-type doping.

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