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

Abstract

The present invention discloses a deep ultraviolet light-emitting diode epitaxial wafer, a preparation method thereof, and a deep ultraviolet LED. The deep ultraviolet light-emitting diode epitaxial wafer includes a substrate and a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlBN layer, and a P-type contact layer that are sequentially stacked on the substrate. The P-type AlBN layer includes an MgN layer / Al x B 1‑x N layer superlattice layer and an Mg-doped Al x B 1‑x N layer, where the value range of x is 0.1-0.5. The deep ultraviolet light-emitting diode epitaxial wafer provided by the present invention can increase the activation Mg concentration of the P-type AlGaN layer, reduce the light absorption of the P-type AlGaN layer, and improve the photoelectric conversion efficiency of the deep ultraviolet light-emitting diode.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic technologies, and particularly to a deep ultraviolet light-emitting diode epitaxial wafer, a preparation method thereof, and a deep ultraviolet LED. Background Art

[0002] Ultraviolet rays are the general term for the radiation wavelength range from 400 nm to 10 nm in the electromagnetic wave spectrum, which is outside the visible light range and cannot cause visual responses in people. The ultraviolet rays in the UV-A band are hardly absorbed by the ozone layer, can promote the synthesis of vitamin D in the human body, and are widely used in fields such as ultraviolet curing and anti-counterfeiting detection; 90% of the ultraviolet rays in the UV-B band are absorbed by the ozone layer and have potential application values in medical diagnosis and biochemical sensing, etc.; the ultraviolet rays in the UV-C band are completely absorbed by the ozone layer when passing through the earth's stratosphere, making the ultraviolet radiation in this band approximately zero, forming a solar blind area of ultraviolet radiation. Due to the short wavelength of this band, it can be applied to fields such as sterilization and disinfection and secure communication. It is precisely because ultraviolet rays have so many important application values that the development of efficient and stable ultraviolet light sources has always been a research and development hotspot internationally.

[0003] Generally, the hole concentration of the P-type GaN layer is increased by increasing the Mg doping concentration in the deep ultraviolet P-type AlGaN layer. However, as the Al content increases, the ionization energy of Mg doping increases, making it difficult to prepare high-doping-concentration P-type AlGaN thin film materials. The ionization energy of its Mg doping is as high as 600 meV, which also poses a huge challenge to the preparation of P-type electrodes. In the prior art, the deep ultraviolet P-type AlGaN layer has the following defects: First, the Mg doping concentration of the P-type AlGaN layer is relatively high, and the deep ultraviolet light emitted by the deep ultraviolet light-emitting diode has a short wavelength, resulting in serious light absorption in the P-type AlGaN layer; Second, the high Al component concentration of the deep ultraviolet P-type AlGaN leads to an increase in the P-type doping ionization energy, reducing the hole concentration in the P-type AlGaN layer. 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, which can increase the activation Mg concentration of the P-type AlGaN layer, reduce the light absorption of the P-type AlGaN layer, and improve the photoelectric conversion efficiency of the deep ultraviolet light-emitting diode.

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

[0006] To solve the above technical problems, the present invention provides a deep ultraviolet light emitting diode epitaxial wafer, comprising a substrate and a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlBN layer, and a P-type contact layer that are sequentially stacked on the substrate;

[0007] The P-type AlBN layer includes an MgN layer / Al x B 1-x N layer superlattice layer and an Mg-doped Al x B 1-x N layer, where the value range of x is 0.1 - 0.5.

[0008] In one embodiment, the MgN layer / Al x B 1-x N layer superlattice layer is an alternately stacked MgN layer and Al x B 1-x N layer, and the alternate stacking period is 3 - 10.

[0009] In one embodiment, the total thickness of the MgN layer / Al x B 1-x N layer superlattice layer is 5 nm - 10 nm;

[0010] The thickness of the Mg-doped Al x B 1-x N layer is 10 nm - 50 nm.

[0011] In one embodiment, the Mg doping concentration of the Mg-doped Al x B 1-x N layer is 5*10 19 atoms / cm 3 -5*10 20 atoms / cm 3 .

[0012] In one embodiment, in the MgN layer / Al x B 1-x N layer superlattice layer, the thickness ratio of the MgN layer to the Al x B 1-x N layer is 1:(1 - 5).

[0013] To solve the above problems, the present invention also provides a method for preparing a deep ultraviolet light emitting diode epitaxial wafer, comprising the following steps:

[0014] Prepare a substrate;

[0015] A buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlBN layer, and a P-type contact layer are sequentially deposited on the substrate;

[0016] The P-type AlBN layer includes an MgN layer / Al x B 1-x N layer superlattice layer and an Mg-doped Al x B 1-x N layer, where x ranges from 0.1 to 0.5.

[0017] In one embodiment, depositing the MgN layer / Al x B 1-x N layer superlattice layer on the electron blocking layer includes the following steps:

[0018] Controlling the reaction chamber temperature at 1000°C - 1100°C, the pressure at 50 torr - 300 torr, introducing N2, H2, and NH3 as carrier gases, first introducing an N source and an Mg source to complete the deposition of the MgN layer, and then completing the deposition of the Al x B 1-x N layer deposition, and the MgN layer and Al x B 1-x N layers are alternately deposited for 3 - 10 cycles.

[0019] In one embodiment, depositing the Mg-doped Al x B 1-x N layer on the MgN layer / Al x B 1- x N layer includes the following steps:

[0020] Controlling the reaction chamber temperature at 1000°C - 1100°C, the pressure at 50 torr - 300 torr, introducing N2, H2, and NH3 as carrier gases, and introducing a B source, an N source, an Mg source, and an Al source to complete the deposition.

[0021] In one embodiment, in the carrier gas, the gas introduction ratio of N2:H2:NH3 is 1:(1 - 15):(1 - 10).

[0022] Correspondingly, the present invention also provides a deep ultraviolet LED, and the deep ultraviolet LED includes the deep ultraviolet light-emitting diode epitaxial wafer described above.

[0023] Implementing the present invention has the following beneficial effects:

[0024] The P-type AlBN layer of the present invention includes an MgN layer / Al x B1-x N-layer superlattice layer and Mg-doped Al x B 1-x N layer. The deep ultraviolet light emitted by the deep ultraviolet light-emitting diode has a short wavelength and high energy. Therefore, reducing the Mg doping can effectively reduce the light absorption of the P layer, and increasing the Al component concentration will increase the Mg ionization energy and reduce the hole concentration. The MgN layer / Al x B 1-x N layer superlattice layer forms a tunneling structure. The Mg activation rate of the MgN layer is relatively high, which can effectively reduce the Mg doping concentration of the MgN layer / Al x B 1-x N layer superlattice layer. At the same time, Al x B 1-x The N layer has a wide bandgap and will not absorb deep ultraviolet light. The Mg-doped Al x B 1-x N layer can provide sufficient holes. Since the low Al component concentration has little effect on the ionization energy of Mg, the activated Mg concentration is relatively high. Finally, the activation Mg concentration of the P-type AlGaN layer is increased, the light absorption of the P-type AlGaN layer is reduced, and the photoelectric conversion efficiency of the deep ultraviolet light-emitting diode is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the deep ultraviolet light-emitting diode epitaxial wafer provided by the present invention.

[0026] Among them: substrate 1, buffer layer 2, undoped AlGaN layer 3, N-type AlGaN layer 4, multi-quantum well layer 5, electron blocking layer 6, P-type AlBN layer 7, P-type contact layer 8, MgN layer / Al x B 1-x N layer superlattice layer 71, Mg-doped Al x B 1-x N layer 72. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below.

[0028] Unless otherwise stated or there are contradictions, the terms or phrases used in this article have the following meanings:

[0029] In the present invention, "its combination", "any combination thereof", "any combination mode thereof", etc. include all suitable combination modes of any two or more of the listed items.

[0030] In the present invention, "preferred" only describes the embodiments or examples with better effects. It should be understood that it does not constitute a limitation on the protection scope of the present invention.

[0031] In the present invention, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open-ended technical solution containing the listed features.

[0032] In the present invention, regarding the numerical range, if there is no special description, it includes both endpoints of the numerical range.

[0033] To solve the above problems, the present invention provides a deep ultraviolet light-emitting diode epitaxial wafer, as Figure 1 shown, which includes a substrate 1 and a buffer layer 2, an undoped AlGaN layer 3, an N-type AlGaN layer 4, a multi-quantum well layer 5, an electron blocking layer 6, a P-type AlBN layer 7, and a P-type contact layer 8 that are sequentially stacked on the substrate 1;

[0034] The P-type AlBN layer 7 includes an MgN layer / Al x B 1-x N layer superlattice layer 71 and an Mg-doped Al x B 1-x N layer 72, where the value range of x is 0.1 - 0.5.

[0035] Among them, the value range of x is 0.1 - 0.5. A lower Al component can reduce the ionization energy of Mg. The deep ultraviolet light emitted by the deep ultraviolet light-emitting diode has a shorter wavelength and higher energy. Therefore, reducing Mg doping can effectively reduce the light absorption of the P layer, and increasing the Al component concentration will increase the Mg ionization energy and reduce the hole concentration. The MgN layer / Al x B 1-x N layer superlattice layer forms a tunneling structure. The Mg activation rate of the MgN layer is relatively high, which can effectively reduce the Mg doping concentration of the MgN layer / Al x B 1-x N layer superlattice layer. At the same time, the Al x B 1- x N layer has a relatively wide bandgap and will not absorb deep ultraviolet light. The Mg-doped Al x B 1-x N layer can provide sufficient holes. Since the influence of the lower Al component concentration on the ionization energy of Mg is relatively small, the activated Mg concentration is relatively high. Finally, it realizes increasing the activated Mg concentration of the P-type AlGaN layer, reducing the light absorption of the P-type AlGaN layer, and improving the photoelectric conversion efficiency of the deep ultraviolet light-emitting diode.

[0036] In one embodiment, the MgN layer / Al x B 1-x N layer superlattice layer is an alternately stacked MgN layer and Al x B 1-xN layers, with an alternating stacking period of 3 - 10. In one embodiment, the MgN layer / Al x B 1-x The total thickness of the N-layer superlattice layer is 5 nm - 10 nm; the thickness of the Mg-doped Al x B 1-x N layer is 10 nm - 50 nm. The number of periods and the thickness of the superlattice layer cause the energy band to bend and change. Within the above range, Mg in the MgN layer can be activated more effectively.

[0037] In the MgN layer / Al x B 1-x N-layer superlattice layer, if the thickness of the MgN layer is too thick and the Al x B 1-x N layer is too thin, it will absorb deep ultraviolet light severely; if the thickness of the MgN layer is too thin, the activation of Mg is insufficient, and if the Al x B 1-x N layer is too thick, the thickness ratio is too large, which will affect the tunneling effect of holes. Preferably, in the MgN layer / Al x B 1-x N-layer superlattice layer, the thickness ratio of the MgN layer to the Al x B 1-x N layer is 1:(1 - 5).

[0038] In one embodiment, the Mg doping concentration of the Mg-doped Al x B 1-x N layer is 5 * 10 19 atoms / cm 3 - 5 * 10 20 atoms / cm 3 . A sufficient doping concentration can provide sufficient holes to ensure sufficient recombination of holes and electrons in the quantum well.

[0039] The characteristics of other layered structures are as follows:

[0040] In one embodiment, the substrate is selected from one of sapphire substrate, SiO2 sapphire composite substrate, silicon substrate, silicon carbide substrate, gallium nitride substrate, zinc oxide substrate. Preferably, the substrate is selected as the sapphire substrate. Sapphire is the most commonly used substrate material at present. The sapphire substrate has mature preparation technology, low price, easy cleaning and processing, and good stability at high temperatures.

[0041] In one embodiment, the buffer layer is an AlN buffer layer. The AlN buffer layer provides nucleation centers with the same orientation as the substrate, releases the stress generated by the lattice mismatch between AlGaN and the substrate and the thermal stress generated by the mismatch of the thermal expansion coefficient, provides a flat nucleation surface for further growth, reduces the contact angle of its nucleation growth, enables the island-like grown GaN grains to form a continuous surface at a relatively small thickness, transforms into two-dimensional epitaxial growth, improves the crystal quality of the subsequently deposited AlGaN layer, reduces the dislocation density, and improves the radiative recombination efficiency of the multi-quantum well layer. In one embodiment, the thickness of the buffer layer is 20 nm - 200 nm.

[0042] In one embodiment, the growth temperature of the undoped AlGaN layer is 1000 °C - 1300 °C, the growth pressure is 50 torr - 500 torr, and the growth thickness is 1 μm - 5 μm. Preferably, the growth temperature of the undoped AlGaN layer is 1200 °C, the growth pressure is 100 torr, and the growth thickness is 2 μm - 3 μm. For the undoped AlGaN layer, with a relatively high growth temperature and a relatively low pressure, the prepared GaN has better crystal quality. At the same time, as the thickness of AlGaN increases, the compressive stress is released through stacking faults, the line defects are reduced, the crystal quality is improved, and the reverse leakage current is reduced. However, increasing the thickness of the AlGaN layer consumes a large amount of MO source (metal organic source) materials, greatly increasing the epitaxial cost of the light-emitting diode. Therefore, the thickness is controlled within 2 μm - 3 μm, which not only saves production costs but also enables the GaN material to have relatively high crystal quality.

[0043] In one embodiment, for the N-type AlGaN layer, the growth temperature is 1000 °C - 1300 °C, the Si doping concentration is 1*10 19 atoms / cm 3 - 5*10 20 atoms / cm 3 , and the thickness is 1 μm - 5 μm. Preferably, the growth temperature is 1200 °C, the growth pressure is 100 torr, the growth thickness is 2 μm - 3 μm, and the Si doping concentration is 2.5*10 19 atoms / cm 3 . First, the N-type doped AlGaN layer provides sufficient electrons for the ultraviolet LED to recombine with holes. Second, the resistivity of the N-type doped AlGaN layer is higher than that of the transparent electrode on the P-type GaN layer. Therefore, sufficient Si doping can effectively reduce the resistivity of the N-type GaN layer. Finally, a sufficient thickness of the N-type doped AlGaN layer can effectively release stress and improve the light-emitting efficiency of the light-emitting diode.

[0044] In one embodiment, the multi-quantum well layer is an alternately stacked Al x Ga 1-xN quantum well layer and Al y Ga 1-y N quantum barrier layer, with the number of stacking periods being 3 - 15. Among them, Al x Ga 1-x The growth temperature of the N quantum well layer is 950 °C - 1150 °C, the thickness is 2 nm - 5 nm, the growth pressure is 50 torr - 300 torr, and the Al component is 0.2 - 0.6; Al y Ga 1-y The growth temperature of the N quantum barrier layer is 1000 °C - 1300 °C, the thickness is 5 nm - 15 nm, the growth pressure is 50 torr - 300 torr, and the Al component is 0.4 - 0.8.

[0045] Preferably, the number of stacking periods is 9. Among them, Al x Ga 1-x The growth temperature of the N quantum well layer is 1050 °C, the thickness is 3.5 nm, the pressure is 200 torr, and the Al component is 0.55; Al y Ga 1-y The growth temperature of the N quantum barrier layer is 1150 °C, the thickness is 11 nm, the growth pressure is 200 torr, and the Al component is 0.7. The multi - quantum well is the region where electrons and holes recombine. A reasonable structure design can significantly increase the overlap degree of the electron and hole wave functions, thereby improving the light - emitting efficiency of the LED device.

[0046] In one embodiment, the electron blocking layer is an AlGaN electron blocking layer, with a thickness of 1 nm - 10 nm, a growth temperature of 1000 °C - 1100 °C, a pressure of 100 torr - 300 torr, and the Al component is 0.4 - 0.8. Preferably, the thickness of the AlGaN electron blocking layer is 30 nm, the Al component is 0.75, the growth temperature is 1050 °C, and the growth pressure is 200 torr. In this way, it can effectively limit the electron overflow, reduce the blocking of holes, improve the injection efficiency of holes into the quantum well, reduce the Auger recombination of carriers, and improve the light - emitting efficiency of the light - emitting diode.

[0047] In one embodiment, the growth temperature of the P - type contact layer is 900 °C - 1100 °C, the thickness is 5 nm - 50 nm, the growth pressure is 100 torr - 600 torr, and the Mg doping concentration is 5 * 10 19 atoms / cm 3 - 5 * 10 20 atoms / cm 3 。

[0048] Preferably, the P - type contact layer is a P - type doped AlGaN layer, with a growth temperature of 1050 °C, a thickness of 10 nm, a growth pressure of 200 torr, and the Mg doping concentration is 1 * 1020 atoms / cm 3 The P-type GaN contact layer with a high doping concentration reduces the contact resistance.

[0049] Accordingly, the present invention also provides a method for preparing the above-mentioned deep ultraviolet light-emitting diode epitaxial wafer, including the following steps:

[0050] S1. Prepare a substrate;

[0051] S2. Deposit a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlBN layer, and a P-type contact layer on the substrate in sequence;

[0052] The P-type AlBN layer includes an MgN layer / Al x B 1-x N layer superlattice layer and an Mg-doped Al x B 1-x N layer, where the value range of x is 0.1 - 0.5.

[0053] In one embodiment, the step S2 includes the following steps:

[0054] S21. Deposit an AlN buffer layer on the front surface of the substrate in a PVD.

[0055] S22. Deposit the undoped AlGaN layer on the buffer layer:

[0056] Control the reaction chamber temperature to be 1000°C - 1300°C, the growth pressure to be 50 torr - 500 torr, and introduce an N source, a Ga source, and an Al source to complete the deposition.

[0057] S23. Deposit the N-type AlGaN layer on the undoped AlGaN layer:

[0058] Control the reaction chamber temperature at 1000°C - 1300°C, the pressure at 50 torr - 300 torr, and introduce an Si source, an Al source, an N source, and a Ga source to complete the deposition.

[0059] S24. Deposit the multi-quantum well layer on the N-type AlGaN layer:

[0060] First, control the reaction chamber temperature to be 950°C - 1150°C, the pressure to be 50 torr - 300 torr, and introduce an N source, a Ga source, and an Al source to complete the deposition of the Al x Ga 1-x N quantum well layer, and then control the temperature to be 1000°C - 1300°C, and continue to introduce an N source, a Ga source, and an Al source to complete the deposition of the Al y Ga 1-yDeposit N, and repeat the stacking for 3 - 15 cycles.

[0061] S25. Deposit the electron blocking layer on the multiple quantum well layer:

[0062] Control the reaction chamber temperature at 1000°C - 1100°C, the pressure at 100 torr - 300 torr, introduce N source, Ga source, and Al source to complete the deposition of the AlGaN layer.

[0063] S26. Deposit the MgN layer / Al x B 1-x The N layer superlattice layer includes the following steps:

[0064] Control the reaction chamber temperature at 1000°C - 1100°C, control the pressure at 50 torr - 300 torr, introduce N2, H2, and NH3 as carrier gases. First, introduce N source and Mg source to complete the deposition of the MgN layer, and then complete the deposition of the Al x B 1-x N layer. Deposit the MgN layer and Al x B 1-x N layers alternately for 3 - 10 cycles.

[0065] S27. Deposit on the MgN layer / Al x B 1-x The N layer superlattice layer deposits the Mg-doped Al x B 1-x N layer, including the following steps:

[0066] Control the reaction chamber temperature at 1000°C - 1100°C, control the pressure at 50 torr - 300 torr, introduce N2, H2, and NH3 as carrier gases, and introduce B source, N source, Mg source, and Al source to complete the deposition.

[0067] In one embodiment, in steps S26 and S27, in the carrier gas, the gas introduction ratio of N2:H2:NH3 is 1:(1 - 15):(1 - 10).

[0068] It should be noted that in steps S26 and S27, the growth temperature is 1000°C - 1100°C. A relatively high growth temperature can improve the crystal quality. The growth atmosphere is that the gas introduction ratio of N2:H2:NH3 is 1:(1 - 15):(1 - 10). A relatively high H2 ratio reduces the average molecular density near the growth interface, increases the diffusion length of reaction atoms, makes the surface morphology flat and smooth, has a high crystal quality, and inhibits the self-compensation effect of Mg. The growth pressure is 50 torr - 300 torr, which can promote the atomic mobility of the P-type AlBN layer and can form a two-dimensional plane with a relatively thin thickness.

[0069] S28. Depositing the p-type contact layer on the Mg-doped Al x B 1-x N layer includes the following steps:

[0070] Controlling the reaction chamber temperature at 900°C - 1100°C, the pressure at 100 torr - 600 torr, and introducing an N source, a Mg source, a Ca source, and an Al source to complete the deposition.

[0071] Correspondingly, the present invention also provides a deep ultraviolet LED, which includes the deep ultraviolet light-emitting diode epitaxial wafer described above.

[0072] The above deposition process is completed using an MOCVD device, a CVD device, or a PVD device. The present invention does not limit the deposition method. High-purity N2 (nitrogen) and H2 (hydrogen) are used as carrier gases. High-purity NH3 (ammonia) provides the N (nitrogen) source. The aluminum source is TMAl (trimethylaluminum), the magnesium source is Cp2Mg (bis(cyclopentadienyl)magnesium), TMGa (trimethylgallium) and TEGa (triethylgallium) are respectively used as the gallium source, and silane (SiH4) is used as the n-type dopant, which is not limited to the above examples.

[0073] The following further illustrates the present invention with specific examples:

[0074] Example 1

[0075] This example provides a deep ultraviolet light-emitting diode epitaxial wafer, which includes a substrate and a buffer layer, an undoped AlGaN layer, an n-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a p-type AlBN layer, and a p-type contact layer that are sequentially stacked on the substrate;

[0076] The p-type AlBN layer includes a MgN layer / Al x B 1-x N layer superlattice layer and a Mg-doped Al x B 1-x N layer, where x is 0.35.

[0077] The MgN layer / Al x B 1-x N layer superlattice layer is an alternately stacked MgN layer and Al x B 1-x N layer, and the alternating stacking period is 5. The total thickness of the MgN layer / Al x B 1-x N layer superlattice layer is 8 nm, and the thickness ratio of the MgN layer to the Al x B 1-x N layer is 2:3.

[0078] The Mg-doped Al x B 1-x N layer has a thickness of 35 nm and a Mg doping concentration of 1.5*10 20 atoms / cm 3 .

[0079] The method for preparing the above deep ultraviolet light-emitting diode epitaxial wafer includes the following steps:

[0080] S1. Prepare a substrate;

[0081] S2. Deposit a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlBN layer, and a P-type contact layer on the substrate in sequence;

[0082] The step S2 includes the following steps:

[0083] S21. Deposit an AlN buffer layer on the front surface of the substrate in a PVD.

[0084] S22. Deposit the undoped AlGaN layer on the buffer layer:

[0085] Control the reaction chamber temperature at 1200 °C, the growth pressure at 100 torr, introduce an N source, a Ga source, and an Al source, complete the deposition and control the thickness at 2.5 μm.

[0086] S23. Deposit the N-type AlGaN layer on the undoped AlGaN layer:

[0087] Control the reaction chamber temperature at 1200 °C, the pressure at 100 torr, introduce an Si source, an Al source, an N source, and a Ga source, complete the deposition and control the thickness at 2.5 μm.

[0088] S24. Deposit the multi-quantum well layer on the N-type AlGaN layer:

[0089] First, control the reaction chamber temperature at 1150 °C, the pressure at 200 torr, introduce an N source, a Ga source, and an Al source to complete the deposition of the Al x Ga 1-x N quantum well layer and control the thickness at 3.5 nm with an Al component of 0.55; then control the temperature at 1150 °C, the growth pressure at 200 torr, continue to introduce an N source, a Ga source, and an Al source to complete the deposition of the Al y Ga 1-y N deposition and control the thickness at 11 nm with an Al component of 0.7; repeat the lamination for 9 cycles.

[0090] S25. Deposit the electron blocking layer on the multi-quantum well layer:

[0091] The reaction chamber temperature is controlled at 1050 °C, the pressure is 200 torr, and N source, Ga source and Al source are introduced to complete the deposition of the AlGaN layer with a controlled thickness of 30 nm and an Al component of 0.75.

[0092] S26. Deposit the MgN layer / Al x B 1-x N layer superlattice layer:

[0093] The reaction chamber temperature is controlled at 1050 °C, the pressure is controlled at 150 torr, and N2, H2 and NH3 are introduced in a ratio of 1:5:5 as carrier gases. First, N source and Mg source are introduced to complete the deposition of the MgN layer, and then B source, N source and Al source are introduced to complete the deposition of the Al x B 1-x N layer deposition, and the MgN layer and Al x B 1-x N layers are alternately deposited.

[0094] S27. Deposit the Mg-doped Al x B 1-x N layer on the MgN layer / Al x B 1-x N layer superlattice layer:

[0095] The reaction chamber temperature is controlled at 1050 °C, the pressure is controlled at 150 torr, and B source, N source, Mg source and Al source are introduced to complete the deposition.

[0096] S28. Deposit the p-type contact layer on the Mg-doped Al x B 1-x N layer:

[0097] The reaction chamber temperature is controlled at 1050 °C, the pressure is controlled at 200 torr, and N source, Mg source, Ca source and Al source are introduced to complete the deposition.

[0098] Example 2

[0099] The difference between this example and Example 1 is that the total thickness of the MgN layer / Al x B 1-x N layer superlattice layer is 10 nm, and the rest refers to Example 1.

[0100] Example 3

[0101] The difference between this example and Example 1 is that in the MgN layer / Al x B 1-x N layer superlattice layer, the MgN layer and the Al x B 1-xThe thickness ratio of the N layer is 1:4, and the rest refers to Example 1.

[0102] Example 4

[0103] The difference between this example and Example 1 is that the thickness of the Mg-doped Al x B 1-x N layer is 10 nm, and the rest refers to Example 1.

[0104] Example 5

[0105] The difference between this example and Example 1 is that the MgN layer / Al x B 1-x N layer superlattice layer is an alternating stack of MgN layers and Al x B 1-x N layers, and the alternating stacking period is 10, and the rest refers to Example 1.

[0106] Example 6

[0107] The difference between this example and Example 1 is that the Mg doping concentration of the Mg-doped Al x B 1-x N layer is 5*10 19 atoms / cm 3 , and the rest refers to Example 1.

[0108] Example 7

[0109] The difference between this example and Example 1 is that in the MgN layer / Al x B 1-x N layer superlattice layer and the Mg-doped Al x B 1-x N layer, x is 0.1, and the rest refers to Example 1.

[0110] Comparative Example 1

[0111] This comparative example provides a deep ultraviolet light-emitting diode epitaxial wafer, including a substrate and a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type Al 0.6 Ga 0.4 N layer and a P-type contact layer stacked in sequence on the substrate. Among them, the thickness of the P-type AlGaN layer is 50 nm, and the Mg doping concentration is 1.5*10 20 atoms / cm 3 , and the rest are the same as Example 1.

[0112] The deep ultraviolet light-emitting diode epitaxial wafers prepared in Examples 1 - 7 and Comparative Example 1 were used to prepare 15 mil * 15 mil chips under the same chip process conditions. 300 LED chips were respectively extracted. They were tested under a current of 120 mA / 60 mA, and the light efficiency improvement rate of each example relative to Comparative Example 1 was calculated. The specific test results are shown in Table 1.

[0113] Table 1 shows the performance test results of the deep ultraviolet light-emitting diode epitaxial wafers prepared in Examples 1 - 7.

[0114]

[0115] From the above results, it can be seen that the P-type AlBN layer of the present invention includes a MgN layer / Al x B 1-x N layer superlattice layer and a Mg-doped Al x B 1-x N layer, which are sequentially stacked on the electron blocking layer. The deep ultraviolet light emitted by the deep ultraviolet light-emitting diode has a short wavelength and high energy. Therefore, reducing Mg doping can effectively reduce the light absorption of the P layer, and increasing the Al component concentration will increase the Mg ionization energy and reduce the hole concentration. The MgN layer / Al x B 1-x N layer superlattice layer forms a tunneling structure. The Mg activation rate of the MgN layer is relatively high, which can effectively reduce the Mg doping concentration of the MgN layer / Al x B 1-x N layer superlattice layer. At the same time, the bandgap width of the Al x B 1-x N layer is relatively wide and will not absorb deep ultraviolet light. The Mg-doped Al x B 1-x N layer can provide sufficient holes. Since the Al component concentration is relatively low, the influence on the ionization energy of Mg is relatively small, so the activated Mg concentration is relatively high. Finally, the activation Mg concentration of the P-type AlGaN layer is increased, the light absorption of the P-type AlGaN layer is reduced, and the photoelectric conversion efficiency of the deep ultraviolet light-emitting diode is improved.

[0116] The above is the preferred implementation manner of the invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A deep ultraviolet light emitting diode epitaxial wafer, characterized in that, It includes a substrate and a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlBN layer, and a P-type contact layer that are sequentially stacked on the substrate; The P-type AlBN layer includes an MgN layer / Al superlattice layer and an Mg-doped Al x B 1-x N layer superlattice layer and an Mg-doped Al x B 1-x N layer, where the value range of x is 0.1 - 0.

5.

2. The deep ultraviolet light-emitting diode epitaxial wafer according to claim 1, wherein The MgN layer / Al x B 1-x The N layer superlattice layer is an alternating stack of MgN layers and Al x B 1-x N layers, and the alternating stacking period is 3 - 10.

3. The deep ultraviolet light-emitting diode epitaxial wafer according to claim 1, characterized in that, The MgN layer / Al x B 1-x The total thickness of the x B 1-x N layer superlattice layer is 5 nm to 10 nm; The Mg-doped Al x B 1-x N layer has a thickness of 10 nm - 50 nm.

4. The deep ultraviolet light-emitting diode epitaxial wafer according to claim 1, wherein The Mg-doped Al x B 1-x The Mg doping concentration of the N layer is 5*10 19 atoms / cm 3 -5*10 20 atoms / cm 3 。 5. The deep ultraviolet light-emitting diode epitaxial wafer according to claim 2, wherein, The MgN layer / Al x B 1-x In the N layer superlattice layer, the thickness ratio of the MgN layer to the Al x B 1-x N layer is 1:(1 - 5).

6. A method for preparing a deep ultraviolet light-emitting diode epitaxial wafer according to any one of claims 1-5, characterized in that, It includes the following steps: Prepare a substrate; Deposit a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlBN layer, and a P-type contact layer on the substrate in sequence; The P-type AlBN layer includes an MgN layer / Al superlattice layer and an Mg-doped AlBxNy layer that are sequentially stacked on the electron blocking layer, where x ranges from 0.1 to 0.

5. x B 1-x N layer superlattice layer and Mg-doped Al x B 1-x N layer, where x ranges from 0.1 to 0.

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7. The method for preparing a deep ultraviolet light-emitting diode epitaxial wafer according to claim 6, characterized in that, Depositing the MgN layer / Al on the electron blocking layer x B 1-x The step of the N layer superlattice layer includes the following steps: The reaction chamber temperature is controlled at 1000°C - 1100°C, and the pressure is controlled at 50 torr - 300 torr. N2, H2, and NH3 are introduced as carrier gases. First, the N source and Mg source are introduced to complete the deposition of the MgN layer, and then the B source, N source, and Al source are used to complete the deposition of the Al x B 1-x N layer. The MgN layer and the Al x B 1-x N layers are alternately deposited for 3 - 10 cycles.

8. The method for preparing a deep ultraviolet light-emitting diode epitaxial wafer according to claim 6, wherein On the MgN layer / Al x B 1-x Depositing the Mg-doped Al x B 1-x N layer includes the following steps: Control the reaction chamber temperature at 1000°C - 1100°C and the pressure at 50 torr - 300 torr, introduce N2, H2, and NH3 as carrier gases, and introduce a B source, an N source, a Mg source, and an Al source to complete the deposition.

9. The method for preparing a deep ultraviolet light-emitting diode epitaxial wafer according to claim 7 or 8, characterized in that, In the carrier gas, the gas introduction ratio of N2:H2:NH3 is 1:(1 - 15):(1 - 10).

10. A deep ultraviolet LED, characterized in that, The deep ultraviolet LED includes the deep ultraviolet light-emitting diode epitaxial wafer according to any one of claims 1 - 5.

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