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

Abstract

The application discloses a deep ultraviolet light emitting diode epitaxial wafer and a preparation method thereof, and a deep ultraviolet light emitting diode. The deep ultraviolet light emitting diode epitaxial wafer comprises a substrate, a buffer layer, a non-doped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer which are sequentially stacked on the substrate; the P-type contact layer comprises a MgN nanocluster layer, a non-doped P-type AlN layer, a non-doped P-type Al2O3 layer and a P-type Si layer which are sequentially stacked on the P-type AlGaN layer. The deep ultraviolet light emitting diode epitaxial wafer provided by the application can reduce the contact resistance of the ultraviolet light emitting diode, improve the light extraction efficiency and improve the photoelectric conversion efficiency of the ultraviolet light emitting diode.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optoelectronic technology, in particular to a deep ultraviolet light emitting diode epitaxial wafer, a preparation method thereof and a deep ultraviolet light emitting diode. BACKGROUND

[0002] With the increasing maturity of InGaN-based LED devices, AlGaN-based materials as a representative of III-nitride wide bandgap become the forefront and hotspot of III-nitride semiconductor research at present. Compared with traditional ultraviolet light sources such as mercury vapor lamps and excimer lasers, AlGaN-based solid-state ultraviolet light sources have many advantages such as small size, portability, green environmental protection, easy wavelength tuning, low voltage, low power consumption, and integration, and have broad application prospects in many fields such as medical sterilization, chemical analysis, biotechnology, optical storage lithography, polymer curing, and non-line-of-sight communication.

[0003] The activation energy of Mg acceptor of the AlGaN-based deep ultraviolet light emitting diode increases linearly with the increase of Al component, so that the Mg activation efficiency is much lower than that of GaN-based light emitting diodes. Therefore, the low hole concentration makes it difficult for the AlGaN-based deep ultraviolet light emitting diode to form a good ohmic contact with the electrode of the LED chip, resulting in a high operating voltage of the AlGaN-based deep ultraviolet light emitting diode and a low photoelectric conversion efficiency. For ultraviolet light emitting diodes, a common method to form a good ohmic contact is Mg heavy doping. However, due to the excessively high Mg doping concentration, the crystal quality of the P-type AlGaN layer is poor, and the narrow band gap of Mg increases the light absorption, thereby reducing the external quantum efficiency of the ultraviolet light emitting diode. However, a low doping concentration cannot form a good ohmic contact, which leads to an increase in the operating voltage of the ultraviolet light emitting diode and affects its aging performance. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a deep ultraviolet light emitting diode epitaxial wafer, which can reduce the contact resistance of the ultraviolet light emitting diode, improve the light extraction efficiency, and improve the photoelectric conversion efficiency of the ultraviolet light emitting diode.

[0005] The technical problem to be solved by the present application is also to provide a preparation method of a deep ultraviolet light emitting diode epitaxial wafer, which is simple in process and can stably produce the deep ultraviolet light emitting diode epitaxial wafer with good performance.

[0006] To solve the above technical problems, the present application provides a deep ultraviolet light emitting diode epitaxial wafer, which comprises a substrate and a buffer layer, a non-doped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer successively stacked on the substrate.

[0007] The P-type contact layer comprises a MgN nanocluster layer, a non-doped P-type AlN layer, a non-doped P-type Al2O3 layer and a P-type Si layer which are sequentially stacked on the P-type AlGaN layer.

[0008] In an embodiment, the thickness of the MgN nanocluster layer is 1-10 nm.

[0009] The total thickness of the non-doped P-type AlN layer and the non-doped P-type Al2O3 layer is 4.5-9 nm.

[0010] The thickness of the P-type Si layer is 1-10 nm.

[0011] In an embodiment, the thickness ratio of the non-doped P-type AlN layer to the non-doped P-type Al2O3 layer is 1:(1-5).

[0012] In an embodiment, the Ga doping concentration in the P-type Si layer is 1*10 20 atoms / cm 3 -1*10 21 atoms / cm 3 .

[0013] To solve the above problems, the application provides a preparation method of a deep ultraviolet light emitting diode epitaxial wafer, comprising the following steps:

[0014] Preparation of a substrate;

[0015] Deposition of a buffer layer, a non-doped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer on the substrate in sequence;

[0016] The P-type contact layer comprises a MgN nanocluster layer, a non-doped P-type AlN layer, a non-doped P-type Al2O3 layer and a P-type Si layer which are sequentially stacked on the P-type AlGaN layer.

[0017] In an embodiment, the deposition of the MgN nanocluster layer on the buffer layer comprises the following steps:

[0018] The temperature of the reaction chamber is controlled at 900-1000℃, the pressure is controlled at 300-600 torr, N2 and NH3 are used as carrier gas, and N source and Mg source are used to complete the deposition.

[0019] In an embodiment, the deposition of the non-doped P-type AlN layer on the MgN nanocluster layer comprises the following steps:

[0020] The reaction chamber temperature is controlled at 1000-1100 DEG C, the pressure is controlled at 50-300 torr, N2 and NH3 are introduced as carrier gas, N source and Al source are introduced to complete deposition.

[0021] In one embodiment, depositing the non-P-doped Al2O3 layer on the non-P-doped AlN layer comprises the following steps:

[0022] The reaction chamber temperature is controlled at 1000-1100 DEG C, the pressure is controlled at 50-300 torr, O2 is introduced as carrier gas, and Al source is introduced to complete deposition.

[0023] In one embodiment, depositing the P-type Si layer on the non-P-doped Al2O3 layer comprises the following steps:

[0024] The reaction chamber temperature is controlled at 950-1050 DEG C, the pressure is controlled at 100-500 torr, N2 is introduced as carrier gas, N2, NH3 and H2 are introduced as carrier gas, Ga source and Si source are introduced to complete deposition.

[0025] Correspondingly, the application also provides a deep ultraviolet light emitting diode comprising the deep ultraviolet light emitting diode epitaxial wafer described above.

[0026] The application has the following beneficial effects:

[0027] The P-type contact layer comprises a MgN nanocluster layer, a non-P-doped AlN layer, a non-P-doped Al2O3 layer and a P-type Si layer which are sequentially stacked on the P-type AlGaN layer. The MgN nanocluster layer provides a flat nucleation surface for the growth of the non-P-doped AlN layer, reducing the contact angle of the nucleation growth. The non-P-doped AlN layer controls the density of nucleation points, which is closely related to the density of the subsequent layered structure. The non-P-doped Al2O3 layer introduces Ga atoms, allowing the non-P-doped AlN layer to continue to grow, reducing the lattice mismatch with the subsequent P-type Si layer, and improving the crystal quality of the P-type Si layer. The density of the P-type Si layer is closely related to the dislocation density of the deep ultraviolet epitaxial layer. The P-type Si layer fuses to generate linear defects, reducing the crystal quality of the GaN epitaxial layer. The deposition of the MgN nanocluster layer, the non-P-doped AlN layer and the non-P-doped Al2O3 layer can effectively control the density of the P-type Si layer to control the dislocation density, reduce the defect density, reduce the non-radiative recombination efficiency of the quantum well, and improve the light emitting efficiency of the deep ultraviolet light emitting diode. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The structure of the deep ultraviolet light emitting diode epitaxial wafer provided by the application is shown in the accompanying drawings.

[0029] Wherein: the substrate 1, the buffer layer 2, the undoped AlGaN layer 3, the N-type AlGaN layer 4, the multi-quantum well layer 5, the electron blocking layer 6, the P-type AlGaN layer 7, the P-type contact layer 8, the MgN nanocluster layer 81, the undoped P-type AlN layer 82, the undoped P-type Al2O3 layer 83, the P-type Si layer 84. DETAILED DESCRIPTION

[0030] In order to make the object, technical scheme and advantages of the present application clearer, the present application will be further described in detail below.

[0031] Unless otherwise stated or contradictory, the terms or phrases used in this document have the following meanings:

[0032] In the present application, the "combination thereof", "any combination thereof", "any combination manner thereof" and the like include all suitable combination manners of any two or more items listed.

[0033] In the present application, "preferably" is only to describe the better effect of the implementation or embodiment, and it should be understood that it does not constitute a limitation on the protection scope of the present application.

[0034] In the present application, the technical features described in an open manner include the closed technical solution consisting of the listed features, and also includes the open technical solution containing the listed features.

[0035] In the present application, if no special description is made, the numerical interval includes both endpoints of the numerical interval.

[0036] Generally, in order to obtain a good ohmic contact, the Mg doping concentration of the P-type contact layer is high, but due to the high Al doping component of the ultraviolet light emitting diode, the Mg activation efficiency is low, and it is difficult to obtain a P-type contact layer with low contact resistance, and due to the too high doping concentration, the crystal quality of the P-type contact layer is poor, which increases the light absorption.

[0037] To solve the above problems, the present application provides a deep ultraviolet light emitting diode epitaxial wafer, as shown in the figure, comprising 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 AlGaN layer 7 and a P-type contact layer 8 which are sequentially stacked on the substrate 1. Figure 1

[0038] The P-type contact layer 8 comprises a MgN nanocluster layer 81, an undoped P-type AlN layer 82, an undoped P-type Al2O3 layer 84, and a P-type Si layer 84 which are sequentially stacked on the P-type AlGaN layer 7.

[0039] ​In an embodiment, the MgN nanocluster layer has a thickness of 1-10 nm; if the thickness of the MgN nanocluster layer is too thick, the absorption of deep ultraviolet light is increased, and if the thickness of the MgN nanocluster layer is too thin, the current spreading is not good, and the current crowding effect cannot be improved.

[0040] In an embodiment, the total thickness of the non-P-doped AlN layer and the non-P-doped Al2O3 layer is 4.5-9 nm; preferably, the thickness ratio of the non-P-doped AlN layer to the non-P-doped Al2O3 layer is 1:(1-5). If the total thickness of the non-P-doped AlN layer and the non-P-doped Al2O3 layer is too thin, the total reflection efficiency of deep ultraviolet light is reduced; if the total thickness of the non-P-doped AlN layer and the non-P-doped Al2O3 layer is too thick, the working voltage is sharply increased when the holes pass through the second sub-layer by tunneling effect.

[0041] In an embodiment, the P-type Si layer has a thickness of 1-10 nm; if the thickness of the P-type Si layer is too thin, the ohmic contact with the electrode is not good, and the contact resistance is increased; if the thickness of the P-type Si layer is too thick, the surface of the P-type Si layer is roughened, and the connection with the electrode is not good.

[0042] In an embodiment, the Ga doping concentration of the P-type Si layer is 1*10 20 atoms / cm 3 -1*10 21 atoms / cm 3 If the P-type Si layer has a higher Ga doping concentration, the contact resistance is reduced.

[0043] In the P-type contact layer, the MgN nanocluster layer can improve the current spreading and reduce the current crowding effect. The non-P-doped AlN layer and the non-P-doped Al2O3 layer can reflect the deep ultraviolet light emitted by the quantum well and emit light from the N layer, because the band gap of the non-P-doped AlN layer is 6.2 eV, and the band gap of the non-P-doped Al2O3 layer is 5.8 eV, so the non-P-doped AlN layer and the non-P-doped Al2O3 layer will not absorb the deep ultraviolet light emitting diode, and the refractive index of the non-P-doped AlN layer is 2.1, and the refractive index of the non-P-doped Al2O3 layer is 1.65, which are lower than the refractive index of GaN 2.4, so the light will be totally reflected in the non-P-doped AlN layer and the non-P-doped Al2O3 layer, and the light extraction efficiency of the deep ultraviolet light emitting diode is improved. The P-type Si layer is different from the traditional P-type contact layer, such as the P-type AlGaN layer with high Mg doping, which can reduce the absorption of deep ultraviolet light. The above-mentioned layers cooperate to reduce the contact resistance of the ultraviolet light emitting diode, improve the light extraction efficiency, and improve the photoelectric conversion efficiency of the ultraviolet light emitting diode.

[0044] In addition to the above-mentioned nucleation layer, the other layered structures of the present application have the following characteristics:

[0045] In one embodiment, the substrate is selected from one of sapphire substrate, SiO2sapphire composite substrate, silicon substrate, silicon carbide substrate, gallium nitride substrate, zinc oxide substrate. Preferably, the substrate is selected from sapphire substrate. Sapphire is the most commonly used substrate material at present, and sapphire substrate has a mature preparation process, a relatively low price, is easy to clean and handle, and has good stability at high temperature.

[0046] In one embodiment, the buffer layer is an AlN buffer layer. The use of the AlN buffer layer provides nucleation centers with the same orientation as the substrate, releases stress generated by lattice mismatch between AlGaN and the substrate and thermal stress generated by mismatch of thermal expansion coefficients, further growth provides a flat nucleation surface, reduces the contact angle of nucleation growth, and enables island-shaped GaN grains to be connected into a plane at a smaller thickness, thereby converting into two-dimensional epitaxial growth, improving the crystal quality of the subsequently deposited AlGaN layer, reducing dislocation density, and improving the radiation recombination efficiency of the multi-quantum well layer. In one embodiment, the thickness of the buffer layer is 20 nm-200 nm.

[0047] 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. The undoped AlGaN layer has a high growth temperature and a low pressure, and the crystal quality of the prepared GaN is relatively high. At the same time, as the thickness of the AlGaN layer increases, the compressive stress is released through stacking faults, the linear defects are reduced, the crystal quality is improved, and the reverse leakage is reduced. However, increasing the thickness of the AlGaN layer greatly increases the consumption of MO source metal organic source material, greatly increasing the epitaxial cost of the light-emitting diode. Therefore, the thickness is controlled to be 2 μm-3 μm, which not only saves production cost, but also has relatively high crystal quality of the GaN material.

[0048] In one embodiment, the N-type AlGaN layer has a growth temperature of 1000°C-1300°C, a Si doping concentration of 1*10 19 atoms / cm 3 -5*10 20 atoms / cm 3 , and a thickness of 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, the Si doping concentration is 2.5*10 19 atoms / cm 3First, the N-doped AlGaN layer provides sufficient electrons and holes for recombination. Second, the N-doped AlGaN layer has a higher resistivity than the transparent electrode on the P-doped GaN layer, so that sufficient Si doping can effectively reduce the resistivity of the N-doped GaN layer. Finally, the N-doped AlGaN layer has a sufficient thickness to effectively release stress and improve the light-emitting efficiency of the light-emitting diode.

[0049] In an embodiment, the multiple quantum well layer is an alternating stack of Al x Ga 1-x N quantum well layers and Al y Ga 1-y N quantum barrier layers, with a number of stack periods of 3-15. The Al x Ga 1-x N quantum well layers have a growth temperature of 950-1150°C, a thickness of 2-5 nm, a growth pressure of 50-300 torr, and an Al composition of 0.2-0.6. The Al y Ga 1-y N quantum barrier layers have a growth temperature of 1000-1300°C, a thickness of 5-15 nm, a growth pressure of 50-300 torr, and an Al composition of 0.4-0.8.

[0050] Preferably, the number of stack periods is 9, the Al x Ga 1-x N quantum well layers have a growth temperature of 1050°C, a thickness of 3.5 nm, a pressure of 200 torr, and an Al composition of 0.55. The Al y Ga 1-y N quantum barrier layers have a growth temperature of 1150°C, a thickness of 11 nm, a growth pressure of 200 torr, and an Al composition of 0.7. The multiple quantum well is a region for electron and hole recombination, and a reasonable structure design can significantly increase the degree of overlap of electron and hole wave functions, thereby improving the light-emitting efficiency of the LED device.

[0051] In an embodiment, the electron blocking layer is an AlGaN electron blocking layer with a thickness of 1-10 nm, a growth temperature of 1000-1100°C, and a pressure of 100-300 torr, and an Al composition of 0.4-0.8. Preferably, the AlGaN electron blocking layer has a thickness of 30 nm, an Al composition of 0.75, a growth temperature of 1050°C, and a growth pressure of 200 torr, which can effectively limit electron overflow, reduce the blocking of holes, improve the injection efficiency of holes into the quantum well, reduce carrier Auger recombination, and improve the light-emitting efficiency of the light-emitting diode.

[0052] In an embodiment, the P-type AlGaN layer has a growth temperature of 1000-1100℃, a thickness of 20-200nm, a growth pressure of 100-600torr, a Mg doping concentration of 1*10 19 atoms / cm 3 -5*10 20 atoms / cm 3 .

[0053] Preferably, the P-type AlGaN layer has a growth temperature of 1050℃, a thickness of 100nm, a growth pressure of 200torr, a Mg doping concentration of 5*10 19 atoms / cm 3 A too high Mg doping concentration will damage the crystal quality, while a too low doping concentration will affect the hole concentration. Meanwhile, the P-type doped AlGaN layer can effectively fill the epitaxial layer, obtaining a deep ultraviolet LED epitaxial wafer with a smooth surface.

[0054] Correspondingly, the application further provides a preparation method of the deep ultraviolet light emitting diode epitaxial wafer, comprising the following steps:

[0055] S1, preparing a substrate;

[0056] S2, sequentially depositing a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer on the substrate;

[0057] The P-type contact layer comprises a MgN nanocluster layer, an undoped P-type AlN layer, an undoped P-type Al2O3 layer and a P-type Si layer which are sequentially stacked on the P-type AlGaN layer.

[0058] In an embodiment, the step S2 comprises the following steps:

[0059] S21, depositing an AlN buffer layer on the front surface of the substrate in a PVD.

[0060] S22, depositing the undoped AlGaN layer on the buffer layer:

[0061] The reaction chamber temperature is controlled to be 1000-1300℃, the growth pressure is controlled to be 50-500torr, the N source, Ga source and Al source are introduced, and the deposition is completed.

[0062] S23, depositing the N-type AlGaN layer on the undoped AlGaN layer:

[0063] The reaction chamber temperature is controlled to be 1000-1300℃, the pressure is controlled to be 50-300torr, the Si source, Al source, N source and Ga source are introduced, and the deposition is completed.

[0064] S24, depositing the multi-quantum well layer on the N-type AlGaN layer:

[0065] First, control the reaction chamber temperature at 950-1150℃, the pressure at 50-300torr, and introduce N source, Ga source and Al source to complete Al x Ga 1-x N quantum well layer deposition, then control the temperature at 1000-1300℃, and continue to introduce N source, Ga source and Al source to complete Al y Ga 1-y N deposition, and repeat the layering for 3-15 cycles.

[0066] S25, depositing the electron blocking layer on the multi-quantum well layer:

[0067] Control the reaction chamber temperature at 1000-1100℃, the pressure at 100-300torr, and introduce N source, Ga source and Al source to complete AlGaN layer deposition.

[0068] S26, depositing the P-type AlGaN layer on the electron blocking layer:

[0069] Control the reaction chamber temperature at 1000-1100℃, the pressure at 100-600torr, and introduce Mg source, N source, Ga source and Al source to complete P-type AlGaN layer deposition.

[0070] S27, depositing the MgN nanocluster layer on the P-type AlGaN layer:

[0071] Control the reaction chamber temperature at 900-1000℃, the pressure at 300-600torr, introduce N2 and NH3 as carrier gas, and introduce N source and Mg source to complete deposition.

[0072] S28, depositing the undoped P-type AlN layer on the MgN nanocluster layer:

[0073] Control the reaction chamber temperature at 1000-1100℃, the pressure at 50-300torr, introduce N2 and NH3 as carrier gas, and introduce N source and Al source to complete deposition.

[0074] S29, depositing the undoped P-type Al2O3 layer on the undoped P-type AlN layer:

[0075] Control the reaction chamber temperature at 1000-1100℃, the pressure at 50-300torr, introduce O2 as carrier gas, and introduce Al source to complete deposition.

[0076] S210, depositing the P-type Si layer on the non-P-doped Al2O3 layer:

[0077] The reaction chamber temperature is controlled at 950-1050 DEG C, the pressure is controlled at 100-500 torr, N2 is used as the carrier gas, N2, NH3 and H2 are used as the carrier gas, and the deposition is completed by introducing Ga source and Si source.

[0078] It should be noted that the growth pressure of the MgN nanocluster layer is relatively high, which is helpful for the longitudinal growth of the MgN nanocluster layer to form a nanocluster layer structure; the growth pressure of the non-P-doped AlN layer and the non-P-doped Al2O3 layer is relatively low, which improves the atomic migration rate and enables the non-P-doped AlN layer and the non-P-doped Al2O3 layer to form a plane at a relatively thin thickness; and the suitable growth pressure of the P-type Si layer is conducive to improving the crystal quality of the P-type Si layer.

[0079] Correspondingly, the application also provides a deep ultraviolet light emitting diode including the deep ultraviolet light emitting diode epitaxial wafer described above.

[0080] The deposition process is completed by using MOCVD equipment, CVD equipment or PVD equipment, and the deposition method is not limited in the application. High-purity N2 (nitrogen) and H2 (hydrogen) are used as the carrier gas. High-purity NH3 (ammonia) provides an N (nitrogen) source, TMAl (trimethylaluminum) is selected as the aluminum source, Cp2Mg (magnesiumocene) is selected as the magnesium source, TMGa (trimethylgallium) and TEGa (triethylgallium) are used as the gallium source, respectively, and silane (SiH4) is used as the N-type dopant, which is not limited to the above list.

[0081] The application is further described below by using specific examples:

[0082] Example 1

[0083] The example provides a deep ultraviolet light emitting diode epitaxial wafer, which includes a substrate and a buffer layer, a non-doped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer which are sequentially stacked on the substrate.

[0084] The P-type contact layer includes a MgN nanocluster layer, a non-P-doped AlN layer, a non-P-doped Al2O3 layer and a P-type Si layer which are sequentially stacked on the P-type AlGaN layer.

[0085] The thickness of the MgN nanocluster layer is 7.5 nm, the thickness of the non-P-doped AlN layer is 2.4 nm, the thickness of the non-P-doped Al2O3 layer is 3.6 nm, and the thickness of the P-type Si layer is 5 nm.

[0086] The Ga doping concentration in the P-type Si layer is 6*1020 atoms / cm 3 .

[0087] The preparation method of the deep ultraviolet light emitting diode epitaxial wafer comprises the following steps:

[0088] S1, preparing a substrate;

[0089] S2, sequentially depositing a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer on the substrate;

[0090] The step S2 comprises the following steps:

[0091] S21, depositing an AlN buffer layer on the front surface of the substrate in a PVD.

[0092] S22, depositing the undoped AlGaN layer on the buffer layer:

[0093] The reaction chamber temperature is controlled to be 1200℃, the growth pressure is 100 torr, the N source, the Ga source and the Al source are introduced, the deposition is completed and the thickness is controlled to be 2.5μm.

[0094] S23, depositing the N-type AlGaN layer on the undoped AlGaN layer:

[0095] The reaction chamber temperature is controlled to be 1200℃, the pressure is 100 torr, the Si source, the Al source, the N source and the Ga source are introduced, the deposition is completed and the thickness is controlled to be 2.5μm.

[0096] S24, depositing the multi-quantum well layer on the N-type AlGaN layer:

[0097] First, the reaction chamber temperature is controlled to be 1150℃, the pressure is controlled to be 200 torr, the N source, the Ga source and the Al source are introduced to complete the deposition of the Al x Ga 1-x N quantum well layer and the thickness is controlled to be 3.5nm, the Al component is 0.55; then the temperature is controlled to be 1150℃, the growth pressure is 200 torr, the N source, the Ga source and the Al source are continuously introduced to complete the deposition of the Al y Ga 1-y N and the thickness is controlled to be 11nm, the Al component is 0.7; the layer is repeated for 9 periods.

[0098] S25, depositing the electron blocking layer on the multi-quantum well layer:

[0099] The reaction chamber temperature is controlled to be 1050℃, the pressure is 200 torr, the N source, the Ga source and the Al source are introduced to complete the deposition of the AlGaN layer and the thickness is controlled to be 30nm, the Al component is 0.75.

[0100] S26, depositing the P-type AlGaN layer on the electron blocking layer:

[0101] The reaction chamber temperature is controlled at 1050℃, the pressure is controlled at 200 torr, the Mg source, N source, Ga source and Al source are introduced to complete the deposition of the P-type AlGaN layer and control the thickness to be 100 nm, and the Mg doping concentration is 5*10 19 atoms / cm 3 .

[0102] S27, depositing the MgN nanocluster layer on the P-type AlGaN layer:

[0103] The reaction chamber temperature is controlled at 950℃, the pressure is controlled at 500 torr, N2 and NH3 are introduced as carrier gas, and the N source and Mg source are introduced to complete the deposition.

[0104] S28, depositing the undoped P-type AlN layer on the MgN nanocluster layer:

[0105] The reaction chamber temperature is controlled at 1050℃, the pressure is controlled at 100 torr, N2 and NH3 are introduced as carrier gas, and the N source and Al source are introduced to complete the deposition.

[0106] S29, depositing the undoped P-type Al2O3 layer on the undoped P-type AlN layer:

[0107] The reaction chamber temperature is controlled at 1050℃, the pressure is controlled at 100 torr, O2 is introduced as carrier gas, and the Al source is introduced to complete the deposition.

[0108] S210, depositing the P-type Si layer on the undoped P-type Al2O3 layer:

[0109] The reaction chamber temperature is controlled at 1000℃, the pressure is controlled at 200 torr, N2 is introduced as carrier gas, N2, NH3 and H2 are introduced as carrier gas, and the Ga source and Si source are introduced to complete the deposition.

[0110] Example 2

[0111] The difference between this example and Example 1 is that the thickness of the MgN nanocluster layer is 2 nm, and the rest refers to Example 1.

[0112] Example 3

[0113] The difference between this example and Example 1 is that the thickness of the MgN nanocluster layer is 10 nm, and the rest refers to Example 1.

[0114] Example 4

[0115] The embodiment differs from embodiment 1 in that the non-doped P-type AlN layer has a thickness of 3 nm and the non-doped P-type Al2O3 layer has a thickness of 6 nm. The rest is as in embodiment 1.

[0116] Embodiment 5

[0117] The embodiment differs from embodiment 1 in that the non-doped P-type AlN layer has a thickness of 0.9 nm and the non-doped P-type Al2O3 layer has a thickness of 3.6 nm. The rest is as in embodiment 1.

[0118] Embodiment 6

[0119] The embodiment differs from embodiment 1 in that the P-type Si layer has a thickness of 2.5 nm. The rest is as in embodiment 1.

[0120] Embodiment 7

[0121] The embodiment differs from embodiment 1 in that the P-type Si layer has a thickness of 7.5 nm. The rest is as in embodiment 1.

[0122] Embodiment 8

[0123] The embodiment differs from embodiment 1 in that the Ga doping concentration in the P-type Si layer is 8.5*10 20 atoms / cm 3 . The rest is as in embodiment 1.

[0124] Embodiment 9

[0125] The embodiment differs from embodiment 1 in that the Ga doping concentration in the P-type Si layer is 3.8*10 20 atoms / cm 3 . The rest is as in embodiment 1.

[0126] Comparative Example 1

[0127] The comparative example provides a deep ultraviolet light emitting diode epitaxial wafer which differs from embodiment 1 in that the P-type contact layer is a P-type AlGaN contact layer having a thickness of 20 nm and a Mg doping concentration of 1.8*10 21 atoms / cm 3 . The rest is as in embodiment 1.

[0128] Comparative Example 2

[0129] The comparative example provides a deep ultraviolet light emitting diode epitaxial wafer which differs from embodiment 1 in that the P-type contact layer does not comprise a MgN nanocluster layer. The rest is as in embodiment 1.

[0130] Comparative Example 3

[0131] The comparative example provides a deep ultraviolet light emitting diode epitaxial wafer, which is different from example 1 in that the P-type contact layer does not include a non-doped P-type AlN layer. The rest is the same as example 1.

[0132] Comparative example 4

[0133] The comparative example provides a deep ultraviolet light emitting diode epitaxial wafer, which is different from example 1 in that the P-type contact layer does not include a non-doped P-type Al2O3 layer. The rest is the same as example 1.

[0134] Comparative example 5

[0135] The comparative example provides a deep ultraviolet light emitting diode epitaxial wafer, which is different from example 1 in that the P-type contact layer does not include a P-type Si layer. The rest is the same as example 1.

[0136] The deep ultraviolet light emitting diode epitaxial wafers prepared from example 1 to example 9 and comparative example 1 to comparative example 5 are prepared into 15mil*15mil chips using the same chip process conditions. 300 LED chips are extracted respectively. The light efficiency improvement rate of each example relative to comparative example 1 is calculated under a test current of 120mA / 60mA. The specific test results are shown in Table 1.

[0137] Table 1 is the performance test results of the deep ultraviolet light emitting diode epitaxial wafers prepared from example 1 to example 9

[0138]

[0139] From the above results, it can be seen that in the P-type contact layer, the MgN nanocluster layer can improve current spreading and reduce current crowding effect. The non-doped P-type AlN layer and the non-doped P-type Al2O3 layer can reflect the deep ultraviolet light emitted by the quantum well from the N layer. Because the band gap of the non-doped P-type AlN layer is 6.2eV and the band gap of the non-doped P-type Al2O3 layer is 5.8eV, the non-doped P-type AlN layer and the non-doped P-type Al2O3 layer will not absorb the deep ultraviolet light emitting diode, and the refractive index of the non-doped P-type AlN layer is 2.1 and the refractive index of the non-doped P-type Al2O3 layer is 1.65, which are lower than the refractive index of GaN 2.4, so the light will be totally reflected in the non-doped P-type AlN layer and the non-doped P-type Al2O3 layer, thereby improving the light extraction efficiency of the deep ultraviolet light emitting diode. The P-type Si layer is different from the traditional P-type contact layer, such as the high-doped Mg P-type AlGaN layer, which can reduce the absorption of deep ultraviolet light. Under the cooperation of the above layers, the contact resistance of the ultraviolet light emitting diode is reduced, the light extraction efficiency is improved, and the photoelectric conversion efficiency of the ultraviolet light emitting diode is improved.

[0140] The above describes the preferred embodiments of the present application, it should be pointed out that, for those skilled in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements are also considered to be within the scope of the present application.

Claims

1. A deep ultraviolet light-emitting diode epitaxial wafer, characterized in that: It includes a substrate and a buffer layer, a non-doped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer stacked in sequence on the substrate; The P-type contact layer includes a MgN nanocluster layer, a non-P-doped AlN layer, a non-P-doped Al2O3 layer, and a P-type Si layer sequentially stacked on the P-type AlGaN layer; The thickness of the MgN nanocluster layer is 1 nm to 10 nm; The total thickness of the non-P-doped AlN layer and the non-P-doped Al2O3 layer is 4.5nm-9nm; The thickness of the P-type Si layer is 1 nm-10 nm.

2. The deep ultraviolet light-emitting diode epitaxial wafer according to claim 1, wherein: The thickness ratio of the non-P-doped AlN layer to the non-P-doped Al2O3 layer is 1:(1-5).

3. The deep ultraviolet light-emitting diode epitaxial wafer according to claim 1, wherein: The Ga doping concentration in the P-type Si layer is 1*10 20 atoms / cm 3 -1*10 21 atoms / cm 3 .

4. A method for preparing a deep ultraviolet light-emitting diode epitaxial wafer according to any one of claims 1 to 3, characterized in that: The following steps are involved: preparing the substrate; Depositing a buffer layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer in sequence on the substrate; The P-type contact layer includes a MgN nanocluster layer, a non-P-doped AlN layer, a non-P-doped Al2O3 layer and a P-type Si layer sequentially stacked on the P-type AlGaN layer.

5. The method for preparing a deep ultraviolet light-emitting diode epitaxial wafer according to claim 4, wherein: Depositing the MgN nanocluster layer on the buffer layer comprises the following steps: The temperature of the reaction chamber is controlled at 900°C-1000°C, the pressure is controlled at 300torr-600torr, N2 and NH3 are introduced as carrier gases, and N source and Mg source are introduced to complete the deposition.

6. The method for preparing a deep ultraviolet light-emitting diode epitaxial wafer according to claim 4, wherein: Depositing the non-P-doped AlN layer on the MgN nanocluster layer comprises the following steps: The temperature of the reaction chamber is controlled at 1000℃-1100℃, the pressure is controlled at 50torr-300torr, N2 and NH3 are introduced as carrier gases, and N source and Al source are introduced to complete the deposition.

7. The method for preparing a deep ultraviolet light-emitting diode epitaxial wafer according to claim 4, wherein: Depositing the non-P-doped Al2O3 layer on the non-P-doped AlN layer comprises the following steps: The temperature of the reaction chamber is controlled at 1000°C-1100°C, the pressure is controlled at 50torr-300torr, O2 is introduced as a carrier gas, and an Al source is introduced to complete the deposition.

8. The method for preparing a deep ultraviolet light-emitting diode epitaxial wafer according to claim 4, wherein: Depositing the P-type Si layer on the non-P-doped Al2O3 layer comprises the following steps: The temperature of the reaction chamber is controlled at 950℃-1050℃, the pressure is controlled at 100torr-500torr, N2 is introduced as carrier gas, N2, NH3 and H2 are introduced as carrier gas, and Ga source and Si source are introduced to complete deposition.

9. A deep ultraviolet light-emitting diode, characterized in that: The deep ultraviolet light emitting diode comprises the deep ultraviolet light emitting diode epitaxial wafer according to any one of claims 1 to 3.

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