Deep ultraviolet light emitting diode epitaxial wafer and preparation method thereof, deep ultraviolet LED

Abstract

The application discloses a deep ultraviolet light emitting diode epitaxial wafer and a preparation method thereof and a deep ultraviolet LED, and the deep ultraviolet light emitting diode epitaxial wafer comprises a substrate and a buffer layer, an N-type semiconductor layer, a multi-quantum well layer, a P-type semiconductor layer, an electron blocking layer, a P-type transition layer and a P-type contact layer which are sequentially stacked on the substrate; the P-type semiconductor layer comprises an Al x GaN gradient layer, an Al m Ga(In n )N hole injection layer and an Al y GaN gradient layer in sequence on the multi-quantum well layer, wherein x ranges from 0.3 to 1, y ranges from 0.3 to 1, 0.3<=m<=0.8 and n<=0.05. The deep ultraviolet light emitting diode epitaxial wafer provided by the application can improve the hole injection efficiency and quality of the P-type material, enhance the matching degree of the active region electron hole, and thus improve the light emitting efficiency of the ultraviolet light emitting diode.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, and in particular to a deep ultraviolet light-emitting diode epitaxial wafer and its preparation method, and a deep ultraviolet LED. Background Technology

[0002] Ultraviolet light-emitting diodes based on group III nitride semiconductor materials have a series of excellent characteristics such as small size and portability, easy integration, mercury-free and environmentally friendly, low power consumption, and rapid switching. The emission wavelength covers the long-wave ultraviolet (UVA, 315-400nm), medium-wave ultraviolet (UVB, 280-315nm) to short-wave ultraviolet (UVC, 210-280nm) bands. They have a wide range of applications in sterilization and disinfection, medical and health care, industrial catalysis, photopolymerization, non-line-of-sight communication and biochemical detection, and are regarded as an ideal choice to replace traditional ultraviolet light sources such as mercury lamps.

[0003] However, it is difficult to obtain high-quality, high-hole-concentration P-type AlGaN materials, which are the main materials for deep ultraviolet LEDs. Mg is the most commonly used P-type dopant in LEDs. The activation energy of Mg as an acceptor dopant in GaN is 200 meV, and it reaches 630 meV in AlN with increasing band gap. This high activation energy leads to a very low ionization rate. In the ultraviolet and deep ultraviolet spectral regions, the ionization rate of Mg decreases significantly with the increase of Al content in AlGaN, resulting in a generally low hole concentration in P-type AlGaN, typically around 10. 17 / cm 3 The order of magnitude is approximately 1 / 3. Furthermore, as the main functional layer of an LED, the electron blocking layer not only blocks electron injection into the P-type layer for light emission but also blocks hole injection into the active region, exacerbating the electron-hole concentration mismatch problem in the active region. Therefore, improving the hole concentration and injection efficiency of the P-type material is essential to enhancing the efficiency of deep ultraviolet LEDs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a deep ultraviolet light-emitting diode epitaxial wafer that can improve the hole injection efficiency and quality of P-type material, enhance the electron-hole matching degree in the active region, and thus improve the luminous efficiency of ultraviolet light-emitting diode.

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a deep ultraviolet light-emitting diode epitaxial wafer, which has a simple process and can stably produce the above-mentioned deep ultraviolet light-emitting diode epitaxial wafer with good performance.

[0006] To solve the above-mentioned technical problems, the present invention provides a deep ultraviolet light-emitting diode epitaxial wafer, comprising a substrate and a buffer layer, an N-type semiconductor layer, a multiple quantum well layer, a P-type semiconductor layer, an electron blocking layer, a P-type transition layer and a P-type contact layer sequentially stacked on the substrate.

[0007] The P-type semiconductor layer includes Al atoms sequentially stacked on the multiple quantum well layer. x GaN gradient layer, Al m Ga(In n N-hole injection layer and Al y GaN graded layers, where x ranges from 0.3 to 1, y ranges from 0.3 to 1, 0.3 ≤ m ≤ 0.8, and n ≤ 0.05.

[0008] In one implementation, the Al x The Al content in the GaN graded layer changes from the multi-quantum-well layer to the Al content. m Ga(In n The number of holes injected decreases sequentially.

[0009] The Al y The Al component content in the GaN graded layer is determined by the Al content. m Ga(In n The number of holes increases sequentially from the hole injection layer to the electron blocking layer;

[0010] The Al m Ga(In n The N-hole injection layer is doped with Mg.

[0011] In one implementation, the Al x The thickness of the GaN gradient layer is 1nm-10nm;

[0012] The Al m Ga(In n The thickness of the N-hole injection layer is 0.01μm-2μm;

[0013] The Al y The thickness of the GaN gradient layer is 2nm-20nm;

[0014] The Al m Ga(In n The Mg doping concentration of the N-hole injection layer is 2 × 10⁻⁶. 18 atoms / cm 3 -5×10 21 atoms / cm 3 .

[0015] In one embodiment, the multiple quantum well layer is an alternating layer of Al.a GaN quantum barrier layer and Al b GaN quantum well layer, the Al a The GaN quantum barrier layer contains Al c Ga(In d N insertion layers, where 0.5≤a≤1, 0<b<a, 0.5≤c≤1, and d≤0.05.

[0016] In one implementation, the Al c Ga(In d The thickness of the N-intercalation layer is 1nm-10nm;

[0017] The Al c Ga(In d The Mg doping concentration of the N-intercalated layer is 2 × 10⁻⁶. 14 atoms / cm 3 -5×10 19 atoms / cm 3 .

[0018] In one embodiment, the P-type transition layer is Al. k GaN layer structure, the Al k In the GaN layer structure, the Al composition decreases sequentially from the electron blocking layer to the P-type contact layer, and the Mg doping concentration increases sequentially from the electron blocking layer to the P-type contact layer, wherein 0≤k≤0.8.

[0019] In one embodiment, the thickness of the P-type transition layer is 0.01 μm-0.5 μm;

[0020] The Mg doping concentration of the P-type transition layer is 1×10⁻⁶. 14 atoms / cm 3 -1×10 22 atoms / cm 3 .

[0021] In one embodiment, the N-type semiconductor layer is Al. e GaN layer, where 0.4≤e≤1;

[0022] The electron blocking layer is an Al composition with a ladder-like decrease in Al content. f GaN layer, where 0.4≤f≤1;

[0023] The P-type ohmic contact layer is a highly Mg-doped Al. g GaN layer, where 0 ≤ g ≤ 0.3.

[0024] To address the above problems, the present invention also provides a method for fabricating a deep ultraviolet light-emitting diode epitaxial wafer, comprising the following steps:

[0025] Prepare the substrate;

[0026] A buffer layer, an N-type semiconductor layer, a multiple quantum well layer, a P-type semiconductor layer, an electron blocking layer, a P-type transition layer, and a P-type contact layer are sequentially deposited on the substrate.

[0027] The P-type semiconductor layer includes Al atoms sequentially stacked on the multiple quantum well layer. x GaN gradient layer, Al m Ga(In n N-hole injection layer and Al y GaN graded layers, where x ranges from 0.3 to 1, y ranges from 0.3 to 1, 0.3 ≤ m ≤ 0.8, and n ≤ 0.05.

[0028] Accordingly, the present invention also provides a deep ultraviolet LED, wherein the deep ultraviolet LED comprises the deep ultraviolet light-emitting diode epitaxial wafer described above.

[0029] Implementing this invention has the following beneficial effects:

[0030] The deep ultraviolet light-emitting diode epitaxial wafer provided by this invention has a P-type semiconductor layer disposed before an electron blocking layer; and the P-type semiconductor layer comprises Al atoms sequentially stacked on the multiple quantum well layer. x GaN gradient layer, Al m Ga(In n N-hole injection layer and Al y GaN graded layers. Using materials with graded Al composition can alleviate lattice mismatch between different sublayers, reduce stress between films, and improve epitaxial layer quality. Try Al... m Ga(In n The N-type hole injection layer provides sufficient holes. The deep ultraviolet LED prepared using this invention can significantly improve the hole injection efficiency and quality of the P-type material, enhance the matching degree of electrons and holes in the active region, and thus improve the luminous efficiency of the ultraviolet light-emitting diode. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the deep ultraviolet light-emitting diode epitaxial wafer provided by the present invention.

[0032] Among them: substrate 1, buffer layer 2, N-type semiconductor layer 3, multiple quantum well layer 4, P-type semiconductor layer 5, electron blocking layer 6, P-type transition layer 7, P-type contact layer 8, Al x GaN gradient layer 51, Al m Ga(In n N-hole injection layer 52, Al y GaN gradient layer 53. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below.

[0034] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0035] In this invention, the terms "combinations thereof", "any combination thereof", and "any combination thereof" include all suitable combinations of any two or more of the listed items.

[0036] In this invention, "preferred" is merely a description of a more effective implementation method or embodiment, and should be understood as not constituting a limitation on the scope of protection of this invention.

[0037] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0038] In this invention, numerical ranges are involved, and unless otherwise specified, they include the two endpoints of the numerical range.

[0039] AlGaN materials with high Al content, as the main material for deep ultraviolet LEDs, have always suffered from low P-type doping efficiency and poor quality, resulting in generally low hole concentration in P-type AlGaN. In addition, the P-type in traditional LEDs is generally placed after the electron blocking layer, which leads to an even lower effective hole concentration injected into the active region by the P-type layer. Ultimately, this makes the problem of electron-hole concentration mismatch in the active region even more severe.

[0040] To address the above problems, this invention provides a deep ultraviolet light-emitting diode epitaxial wafer, such as... Figure 1 As shown, it includes a substrate 1 and a buffer layer 2, an N-type semiconductor layer 3, a multiple quantum well layer 4, a P-type semiconductor layer 5, an electron blocking layer 6, a P-type transition layer 7 and a P-type contact layer 8 sequentially stacked on the substrate 1;

[0041] The P-type semiconductor layer 5 includes Al layers sequentially stacked on the multiple quantum well layer 4. x GaN gradient layer 51, Al m Ga(In n N-hole injection layer 52 and Al y GaN graded layer 53, where x ranges from 0.3 to 1, y ranges from 0.3 to 1, 0.3 ≤ m ≤ 0.8, and n ≤ 0.05.

[0042] The deep ultraviolet light-emitting diode epitaxial wafer provided by this invention has a P-type semiconductor layer disposed before an electron blocking layer; and the P-type semiconductor layer comprises Al atoms sequentially stacked on the multiple quantum well layer. x GaN gradient layer, Al m Ga(In n N-hole injection layer and Al y GaN graded layers. Using materials with graded Al composition can alleviate lattice mismatch between different sublayers, reduce stress between films, and improve epitaxial layer quality. Try Al... m Ga(In n The N-type hole injection layer provides sufficient holes. The deep ultraviolet LED prepared using this invention can significantly improve the hole injection efficiency and quality of the P-type material, enhance the matching degree of electrons and holes in the active region, and thus improve the luminous efficiency of the ultraviolet light-emitting diode.

[0043] In one implementation, the Al x The Al content in the GaN graded layer changes from the multi-quantum-well layer to the Al content. m Ga(In n The N-hole injection layers decrease sequentially; the Al y The Al component content in the GaN graded layer is determined by the Al content. m Ga(In n The number of electrons increases sequentially from the hole injection layer to the electron blocking layer. It should be noted that, compared to using a material layer with a uniform composition, this reduces the blocking effect on hole injection, enhances hole injection efficiency, and simultaneously reduces the mismatch and stress between sublayers, thereby improving the quality of the epitaxial layer. Preferably, the Al... x The Al content in the GaN graded layer decreases according to the following pattern: every 1nm-3nm interval, the Al content decreases by 0.2-0.4%. This not only protects the quantum well but also further reduces the blocking effect on hole injection, decreasing the mismatch and stress between sublayers. y The Al content in the GaN graded layer increases by 0.2-0.4% every 2nm-6nm interval. This increasing pattern minimizes the mismatch and stress between sublayers. m Ga(In n The N-type hole injection layer is doped with Mg. Mg doping provides some holes, further alleviating the hole deficiency in the P-type semiconductor layer. However, excessively high Mg doping concentrations lead to the formation of Mg-N complexes, which exhibit donor characteristics, resulting in a severe self-compensation effect and actually reducing the hole concentration. Conversely, excessively low Mg doping concentrations result in insufficient hole concentration, affecting electron-hole recombination luminescence in the active region and reducing the device's luminous efficiency. Preferably, the Al... mGa(In n The Mg doping concentration of the N-hole injection layer is 2 × 10⁻⁶. 18 atoms / cm 3 -5×10 21 atoms / cm 3 .

[0044] In one implementation, the Al x The thickness of the GaN gradient layer is 1nm-10nm; the Al m Ga(In n The thickness of the N-hole injection layer is 0.01 μm-2 μm; the Al y The thickness of the GaN gradient layer is 2nm-20nm.

[0045] In general, in conventional structures, the electron blocking layer is placed before the P-type semiconductor layer. In this invention, the P-type semiconductor layer is placed before the electron blocking layer. Thus, the electron blocking layer, as the main functional layer of the LED, not only blocks electron injection into the P-type layer for light emission but also blocks hole injection into the active region. This not only weakens the hole-blocking effect of the electron blocking layer but also enhances the hole injection efficiency. Furthermore, the Al... m Ga(In n The N-hole injection layer serves as the main body for providing holes, and the Al x The GaN graded-layer, while protecting the quantum well structure, reduces the blocking effect on hole injection and decreases the mismatch and stress between sublayers. The Al... y The GaN graded-layer structure further reduces the mismatch and stress between sublayers. The combined effect of these three layers reduces the mismatch between the main functional layers, thereby reducing inter-film stress and improving epitaxial layer quality.

[0046] In one embodiment, the multiple quantum well layer is an alternating layer of Al. a GaN quantum barrier layer and Al b GaN quantum well layer, the Al a The GaN quantum barrier layer contains Al c Ga(In d N insertion layers, wherein 0.5 ≤ a ≤ 1, 0 < b < a, 0.5 ≤ c ≤ 1, and d ≤ 0.05. Preferably, the Al c Ga(In d The thickness of the N insertion layer is 1nm-10nm.

[0047] It should be noted that, compared with conventional multiple quantum well layers, the present invention describes the Al... a The GaN quantum barrier layer contains Al c Ga(In dThe N-intercalation layer can provide some holes, thereby improving the electron-hole recombination efficiency.

[0048] It should be noted that because the hole concentration in P-type materials is relatively lower than the electron concentration in N-type materials, and the effective mass and mobility of holes are large, the hole injection efficiency is relatively low, thus affecting the luminous efficiency of GaN-based light-emitting diodes. Inserting Al into the barrier layer... c Ga(In d The primary purpose of the N-intercalation layer is to provide some holes, thereby increasing the hole concentration and luminous efficiency of the emissive layer. Intercalation in the well layer reduces the quality of the emissive layer, increases defects and non-radiative recombination, and reduces luminous efficiency. The Al... c Ga(In d When the Mg doping concentration in the N-intercalation layer is too high, Mg-N complexes will form. These complexes all exhibit donor characteristics, resulting in a severe self-compensation effect and consequently reducing the hole concentration. Conversely, if the Mg doping concentration is too low, insufficient hole concentration will lead to inadequate hole concentration, affecting electron-hole recombination luminescence in the active region and reducing the device's luminous efficiency. Preferably, the Al... c Ga(In d The Mg doping concentration of the N-intercalated layer is 2 × 10⁻⁶. 14 atoms / cm 3 -5×10 19 atoms / cm 3 .

[0049] In one embodiment, the P-type transition layer is Al. k GaN layer structure, the Al k In the GaN layer structure, the Al composition decreases sequentially from the electron blocking layer to the P-type contact layer, while the Mg doping concentration increases sequentially from the electron blocking layer to the P-type contact layer, wherein 0 ≤ k ≤ 0.8. Preferably, the thickness of the P-type transition layer is 0.01 μm-0.5 μm; the Mg doping concentration of the P-type transition layer is 1 × 10⁻⁶. 14 atoms / cm 3 -1×10 22 atoms / cm 3 The P-type transition layer with the above specific structure can provide some holes to the active region, further alleviating the lack of holes in the P-type material. At the same time, it reduces the lattice mismatch between the P-type ohmic contact layer and improves the quality of the epitaxial layer.

[0050] In one embodiment, the substrate is selected from one of the following: sapphire substrate, SiO2 sapphire composite substrate, silicon substrate, silicon carbide substrate, gallium nitride substrate, and zinc oxide substrate.

[0051] In one embodiment, the N-type semiconductor layer is Al. eGaN layer, wherein 0.4≤e≤1; thickness 0.1μm-20μm, Si concentration 1×10⁻⁶. 18 atoms / cm 3 -1×10 20 atoms / cm 3 .

[0052] In one embodiment, the electron blocking layer is an Al layer with a ladder-like decrease in Al composition. f GaN layer, wherein 0.4≤f≤1; thickness is 1nm-500nm.

[0053] In one embodiment, the P-type ohmic contact layer is a highly Mg-doped Al. g A GaN layer, wherein 0 ≤ g ≤ 0.3 g, with a thickness of 1 nm–500 nm and a Mg concentration of 2 × 10⁻⁶ g / g. 18 atoms / cm 3 -2×10 22 atoms / cm 3 .

[0054] In summary, this invention places a P-type semiconductor layer before the electron blocking layer, and in the Al... a The GaN quantum barrier layer contains Al doped with Mg. c Ga(In d The addition of an N-type insertion layer, combined with a P-type transition layer exhibiting a gradient decrease in Al composition and an increase in Mg doping concentration, can significantly improve the hole injection efficiency of P-type materials. Simultaneously, the P-type semiconductor layer employs a specific multilayer structure, and the Al... x The Al composition in the GaN graded layer decreases sequentially, wherein the Al y In GaN graded layers, the Al composition increases sequentially. Combined with a specifically structured P-type transition layer, this gradual Al composition reduction alleviates lattice mismatch between different sublayers, decreases stress between films, and improves epitaxial layer quality. Ultimately, this significantly improves the hole injection efficiency and quality of the P-type material, enhances the electron-hole matching degree in the active region, and thus improves the luminous efficiency of ultraviolet light-emitting diodes.

[0055] Accordingly, the present invention also provides a method for preparing the above-mentioned deep ultraviolet light-emitting diode epitaxial wafer, comprising the following steps:

[0056] S1. Prepare the substrate;

[0057] S2. A buffer layer, an N-type semiconductor layer, a multiple quantum well layer, a P-type semiconductor layer, an electron blocking layer, a P-type transition layer, and a P-type contact layer are sequentially deposited on the substrate.

[0058] The P-type semiconductor layer includes Al atoms sequentially stacked on the multiple quantum well layer. xGaN gradient layer, Al m Ga(In n N-hole injection layer and Al y GaN graded layers, where x ranges from 0.3 to 1, y ranges from 0.3 to 1, 0.3 ≤ m ≤ 0.8, and n ≤ 0.05.

[0059] The above preparation process is completed using MOCVD equipment, CVD equipment or PVD equipment, and the present invention does not make specific limitations.

[0060] Accordingly, the present invention also provides a deep ultraviolet LED, wherein the deep ultraviolet LED includes the deep ultraviolet light-emitting diode epitaxial wafer described above.

[0061] The present invention is further illustrated below with specific embodiments:

[0062] Example 1

[0063] This embodiment provides a deep ultraviolet light-emitting diode epitaxial wafer, including a substrate and a buffer layer, an N-type semiconductor layer, a multiple quantum well layer, a P-type semiconductor layer, an electron blocking layer, a P-type transition layer and a P-type contact layer sequentially stacked on the substrate;

[0064] The P-type semiconductor layer includes Al atoms sequentially stacked on the multiple quantum well layer. x GaN gradient layer, Al m Ga(In n N-hole injection layer and Al y A GaN gradient layer, where m is 0.5 and n is 0.03.

[0065] The Al x The Al composition in the GaN graded layer changes from the multi-quantum-well layer to the Al... m Ga(In n The N-hole injection layer decreases in a stepwise manner from 0.8 to 0.4; the Al y The Al component content in the GaN graded layer is determined by the Al content. m Ga(In n The N-hole injection layer increases in a stepwise manner from 0.4 to 0.8 from the electron blocking layer; the Al x The thickness of the GaN gradient layer is 5 nm; the Al m Ga(In n The thickness of the N-hole injection layer is 1 μm; the Al y The thickness of the GaN gradient layer is 10 nm; the Al m Ga(In n The Mg doping concentration of the N-hole injection layer is 1×10⁻⁶. 20 atoms / cm 3 .

[0066] The multiple quantum well layers are Al layers grown in alternating layers. a GaN quantum barrier layer and Al b GaN quantum well layer, the Al a The GaN quantum barrier layer contains Al c Ga(In d N insertion layers, where a is 0.8, b is 0.3, c is 0.6, and d is 0.02. The Al c Ga(In d The Mg doping concentration of the N-intercalation layer is 1×10⁻⁶. 16 atoms / cm 3 .

[0067] The P-type transition layer is Al. k GaN layer structure, the Al k In the GaN layer structure, the Al composition decreases sequentially from the electron blocking layer to the P-type contact layer, while the Mg doping concentration increases sequentially from the electron blocking layer to the P-type contact layer, where k is 0.5, the thickness of the P-type transition layer is 0.3 μm, and the Mg doping concentration is 1 × 10⁻⁶. 19 atoms / cm 3 .

[0068] Example 2

[0069] The difference between this embodiment and Embodiment 1 is that: the Al x The Al composition in the GaN graded layer changes from the multi-quantum-well layer to the Al... m Ga(In n The N-hole injection layer decreases from 1 stepwise to 0.3; the Al y The Al component content in the GaN graded layer is determined by the Al content. m Ga(In n The number of holes injected into the electron blocking layer increases from 0.3 to 1 in a stepwise manner. The rest is the same as in Example 1.

[0070] Example 3

[0071] The difference between this embodiment and Embodiment 1 is that: the Al m Ga(In n The Mg doping concentration of the N-hole injection layer is 1×10⁻⁶. 21 atoms / cm 3 The rest are as described in Example 1.

[0072] Example 4

[0073] The difference between this embodiment and Embodiment 1 is that the multiple quantum well layers are Al layers grown in alternating layers. a GaN quantum barrier layer and Alb GaN quantum well layer, the Al a The GaN quantum barrier layer does not contain Al. c Ga(In d N insertion layer. The rest are as described in Example 1.

[0074] Comparative Example 1

[0075] This comparative example provides a deep ultraviolet light-emitting diode epitaxial wafer, which differs from Example 1 in that: the P-type semiconductor layer includes Al atoms sequentially stacked on the multi-quantum-well layer. x GaN layer, Al m Ga(In n N-hole injection layer and Al y The GaN layer has m = 0.5, n = 0.03, x = 0.6, and y = 0.6. All other parameters are the same as in Example 1.

[0076] Comparative Example 2

[0077] This comparative example provides a deep ultraviolet light-emitting diode epitaxial wafer, which differs from Example 1 in that the P-type semiconductor layer does not have Al. m Ga(In n N-hole injection layer. The rest are the same as in Example 1.

[0078] Comparative Example 3

[0079] This comparative example provides a deep ultraviolet light-emitting diode epitaxial wafer, which differs from Example 1 in that it does not have a P-type transition layer. All other aspects are the same as in Example 1.

[0080] The deep ultraviolet light-emitting diode epitaxial wafers prepared in Examples 1-4 and Comparative Examples 1-3 were fabricated into chips using the same chip manufacturing process. 300 LED chips were randomly selected from each example for testing. Specific test results are shown in Table 1.

[0081] Table 1 shows the performance test results of the deep ultraviolet light-emitting diode epitaxial wafers prepared in Examples 1-4 and Comparative Examples 1-3.

[0082]

[0083] As can be seen from the above results, the present invention places the P-type semiconductor layer before the electron blocking layer, and in the Al... a The GaN quantum barrier layer contains Al doped with Mg. c Ga(In d The addition of an N-type insertion layer, combined with a P-type transition layer exhibiting a gradient decrease in Al composition and an increase in Mg doping concentration, can significantly improve the hole injection efficiency of P-type materials. Simultaneously, the P-type semiconductor layer employs a specific multilayer structure, and the Al...x The Al composition in the GaN graded layer decreases sequentially, wherein the Al y In GaN graded layers, the Al composition increases sequentially. Combined with a specifically structured P-type transition layer, this gradual Al composition reduction alleviates lattice mismatch between different sublayers, decreases stress between films, and improves epitaxial layer quality. Ultimately, this significantly improves the hole injection efficiency and quality of the P-type material, enhances the electron-hole matching degree in the active region, and thus improves the luminous efficiency of ultraviolet light-emitting diodes.

[0084] The above description is a preferred embodiment of the invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A deep ultraviolet light-emitting diode epitaxial wafer, characterized in that, It includes a substrate and a buffer layer, an N-type semiconductor layer, a multiple quantum well layer, a P-type semiconductor layer, an electron blocking layer, a P-type transition layer and a P-type contact layer sequentially stacked on the substrate; The P-type semiconductor layer includes Al atoms sequentially stacked on the multiple quantum well layer. x GaN gradient layer, Al m Ga(In n N-hole injection layer and Al y GaN graded layer, where x ranges from 0.3 to 1, y ranges from 0.3 to 1, 0.3 ≤ m ≤ 0.8, and n ≤ 0.05; The Al x The Al content in the GaN graded layer changes from the multi-quantum-well layer to the Al content. m Ga(In n The number of holes injected decreases sequentially. The Al y The Al component content in the GaN graded layer is determined by the Al content. m Ga(In n The number of holes increases sequentially from the hole injection layer to the electron blocking layer; The Al m Ga(In n The N-hole injection layer is doped with Mg.

2. The deep ultraviolet light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The Al x The thickness of the GaN gradient layer is 1nm-10nm; The Al m Ga(In n The thickness of the N-hole injection layer is 0.01μm-2μm; The Al y The thickness of the GaN gradient layer is 2nm-20nm; The Al m Ga(In n The Mg doping concentration of the N-hole injection layer is 2 × 10⁻⁶. 18 atoms / cm 3 -5×10 21 atoms / cm 3 .

3. The deep ultraviolet light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The multiple quantum well layers are Al layers grown in alternating layers. a GaN quantum barrier layer and Al b GaN quantum well layer, the Al a The GaN quantum barrier layer contains Al c Ga(In d N insertion layers, where 0.5≤a≤1, 0<b<a, 0.5≤c≤1, and d≤0.

05.

4. The deep ultraviolet light-emitting diode epitaxial wafer as described in claim 3, characterized in that, The Al c Ga(In d The thickness of the N-intercalation layer is 1nm-10nm; The Al c Ga(In d The Mg doping concentration of the N-intercalated layer is 2 × 10⁻⁶. 14 atoms / cm 3 -5×10 19 atoms / cm 3 .

5. The deep ultraviolet light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The P-type transition layer is Al. k GaN layer structure, the Al k In the GaN layer structure, the Al composition decreases sequentially from the electron blocking layer to the P-type contact layer, and the Mg doping concentration increases sequentially from the electron blocking layer to the P-type contact layer, wherein 0≤k≤0.

8.

6. The deep ultraviolet light-emitting diode epitaxial wafer as described in claim 5, characterized in that, The thickness of the P-type transition layer is 0.01 μm-0.5 μm; The Mg doping concentration of the P-type transition layer is 1×10⁻⁶. 14 atoms / cm 3 -1×10 22 atoms / cm 3 .

7. The deep ultraviolet light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The N-type semiconductor layer is Al. e GaN layer, where 0.4≤e≤1; The electron blocking layer is an Al composition with a ladder-like decrease in Al content. f GaN layer, where 0.4≤f≤1; The P-type contact layer is a highly Mg-doped Al. g GaN layer, where 0 ≤ g ≤ 0.

3.

8. A method for fabricating a deep ultraviolet light-emitting diode epitaxial wafer as described in any one of claims 1-7, characterized in that, Includes the following steps: Prepare the substrate; A buffer layer, an N-type semiconductor layer, a multiple quantum well layer, a P-type semiconductor layer, an electron blocking layer, a P-type transition layer, and a P-type contact layer are sequentially deposited on the substrate. The P-type semiconductor layer includes Al atoms sequentially stacked on the multiple quantum well layer. x GaN gradient layer, Al m Ga(In n N-hole injection layer and Al y GaN graded layers, where x ranges from 0.3 to 1, y ranges from 0.3 to 1, 0.3 ≤ m ≤ 0.8, and n ≤ 0.

05.

9. A deep ultraviolet LED, characterized in that, The deep ultraviolet LED comprises a deep ultraviolet light-emitting diode epitaxial wafer as described in any one of claims 1-7.

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