A multi-wavelength ultraviolet LED and its preparation method

Abstract

The present invention relates to the field of ultraviolet LED technology, and provides a multi-wavelength luminous ultraviolet LED and a preparation method thereof. The multi-wavelength luminous ultraviolet LED of the present invention comprises a substrate and an AlN template layer, an AlN thin film layer, an N-type intensity adjustment layer, an n-AlGaN layer, a quantum well light-emitting layer, an electron blocking layer, a P-type AlGaN layer and a P-type ohmic contact layer, which are located on the surface of the substrate and stacked in sequence; the quantum well light-emitting layer comprises at least two quantum well light-emitting layers with different luminous wavelengths, and the structure and growth temperature of each quantum well light-emitting layer are different; the present invention does not need to change the thickness and composition of the quantum well light-emitting layer to achieve ultraviolet LED light emission of different wavelengths, but instead achieves ultraviolet LED light emission of different wavelengths by changing the structure of the potential well layer; by adjusting the thickness of the n-AlN layer in the N-type intensity adjustment layer, thereby affecting the stress of the quantum well light-emitting layer, the relative intensity of ultraviolet light of different wavelengths is adjusted to meet various different application requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of ultraviolet LEDs, and in particular to a multi-wavelength luminous ultraviolet LED and a preparation method thereof. Background Art

[0002] Ultraviolet disinfection technology has gained widespread application due to its clean, environmentally friendly nature and the absence of disinfection byproducts. AlGaN-based light-emitting diodes (LEDs), as a new generation of UV light sources, have attracted significant attention and interest from researchers due to their environmentally friendly, compact size, long lifespan, and tunable wavelength. They offer significant potential for development and application in areas such as air and water purification, biochemical testing, and sterilization. By adjusting the Al content in the AlGaN active region, deep-UV LEDs can emit light in the 200-365nm UV range. UVC, with a wavelength between 200 and 280nm, is widely used for sterilization and disinfection of surfaces and fluids such as air and water. UVB, with a wavelength between 280 and 320nm, has significant potential for water purification, skin disease treatment, and plant and animal growth support.

[0003] In recent years, ultraviolet LEDs have experienced rapid development, with the bio-safe 230nm far-UVC LED garnering widespread attention. However, UV LEDs face challenges such as difficult carrier injection, low radiative recombination efficiency, and inefficient light extraction. These issues contribute to generally low photoelectric conversion efficiencies, which also decline rapidly with decreasing wavelength.

[0004] Currently, most AlGaN-based UV LEDs emit at a single wavelength. Achieving multi-wavelength UV emission requires integrating UV LED chips with different wavelengths, which increases both the complexity and the cost. Therefore, developing AlGaN-based UV LED epitaxial structures with multi-band wavelengths, and thereby enabling multi-wavelength UV LED chips, is crucial for achieving UV LEDs with multiple functions. Furthermore, this approach can significantly simplify the size of UV LED disinfection devices, reducing costs. Summary of the Invention

[0005] In view of the above-mentioned shortcomings, the object of the present invention is to provide a multi-wavelength ultraviolet LED that can realize multi-wavelength light emission and has adjustable light emission intensity, and a preparation method thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a multi-wavelength ultraviolet LED, comprising: a substrate and an AlN template layer, an AlN thin film layer, an N-type intensity adjustment layer, an n-AlGaN layer, a quantum well light-emitting layer, an electron blocking layer, a P-type AlGaN layer, and a P-type ohmic contact layer, which are located on the surface of the substrate and stacked in sequence;

[0008] Wherein, the quantum well light-emitting layer includes at least two quantum well light-emitting layers with different light-emitting wavelengths.

[0009] Preferably, the N-type strength adjustment layer is n-Al x Ga 1-x N / n-AlN superlattice periodic structure layer; wherein the thickness of n-AlN is 0.5~10nm, and the thickness of n-Al x Ga 1-x The thickness of N is 5-50 nm, the thickness of the N-type strength adjustment layer is ≥0.5 μm, and 0.7≤x<1.

[0010] Preferably, the quantum well light-emitting layer comprises a long wavelength quantum well light-emitting layer, a first short wavelength quantum well light-emitting layer, and a second short wavelength quantum well light-emitting layer stacked in sequence;

[0011] Wherein, the long-wavelength quantum well light-emitting layer is an AlGaN / AlN quantum well light-emitting layer, the thickness of the AlGaN well layer is 1-10 nm, the thickness of the AlN barrier layer is 2-10 nm, and the number of quantum well periods of the long-wavelength quantum well light-emitting layer is 1-3;

[0012] The first short-wavelength quantum well light-emitting layer includes an AlGaN / AlN / AlGaN well layer and an AlN barrier layer, wherein the thickness of the AlN barrier layer is 2-10 nm, the thickness of the AlGaN / AlN / AlGaN well layer is 2-8 nm, and the thickness of the AlN layer in the well layer is 0.1-1 nm; the number of quantum well periods in the first short-wavelength quantum well light-emitting layer is 1-3;

[0013] The second short-wavelength quantum well light-emitting layer includes an AlGaN / AlN / AlGaN well layer and an AlN barrier layer. The thickness of the AlN barrier layer is 1 to 6 nm, the thickness of the AlGaN / AlN / AlGaN well layer is 1 to 4 nm, and the thickness of the AlN layer in the well layer is 0.1 to 1.5 nm. The number of quantum well periods in the second short-wavelength quantum well light-emitting layer is 1 to 3.

[0014] Preferably, the n-AlGaN layer comprises n-Al y Ga 1-y N layer, n-Al z Ga 1-z N-layer;

[0015] The n-Al y Ga1-y The thickness of the N layer is 200~1000nm;

[0016] The n-Al z Ga 1-z The thickness of the N layer is 0.1~100nm;

[0017] Among them, 0.7≤y≤x≤z<1.

[0018] Preferably, the electron blocking layer is a P-AlGaN layer, the P-AlGaN layer is a P-AlaGa1-aN layer, 0.8≤a<1, and the thickness of the electron blocking layer is 0.5-50 nm.

[0019] Preferably, the P-type AlGaN layer is P-Al b Ga 1-b N layer, 0.5≤b<1, P-type AlGaN layer thickness 50~500nm.

[0020] Preferably, the P-type ohmic contact layer is a P-type GaN layer with a thickness of 0.5 to 50 nm;

[0021] The thickness of the AlN thin film layer is 50nm to 500nm.

[0022] In a second aspect, the present invention further provides a method for preparing the multi-wavelength ultraviolet LED, comprising the following steps:

[0023] An AlN template layer, an AlN thin film layer, an N-type strength adjustment layer, an n-AlGaN layer, a quantum well light-emitting layer, an electron blocking layer, a P-type AlGaN layer and a P-type ohmic contact layer are sequentially grown on the substrate.

[0024] Preferably, an AlN template layer is grown on the substrate, and an AlN thin film layer is grown on the AlN template layer; the AlN thin film layer growth temperature is 1100° C. to 1300° C.;

[0025] An N-type strength adjustment layer is grown on the AlN thin film layer. The N-type strength adjustment layer is n-Al x Ga 1-x N / n-AlN superlattice periodic structure layer, growth temperature 1000℃~1200℃, carrier concentration 5×10 17 ~1×10 19 cm -3 ;

[0026] An n-AlGaN layer is grown on the N-type strength adjustment layer, wherein the n-AlGaN layer comprises n-Al y Ga 1-y N layer, n-Al z Ga 1-zN layer, in which n-Al y Ga 1-y The thickness of the N layer is 0.2~1μm, the growth temperature is 1000℃~1200℃, and the carrier concentration is 1×10 18 ~1×10 19 cm -3 ;

[0027] n-Al z Ga 1-z The thickness of the N layer is 0.1~100nm, the growth temperature is 1000℃~1200℃, and the carrier concentration is 1×10 17 ~1×10 18 cm -3 ;

[0028] A quantum well light-emitting layer is grown on the n-AlGaN layer; the quantum well light-emitting layer comprises a long-wavelength quantum well light-emitting layer, a first short-wavelength quantum well light-emitting layer, and a second short-wavelength quantum well light-emitting layer stacked in sequence; wherein the long-wavelength quantum well light-emitting layer is an AlGaN / AlN quantum well light-emitting layer, the AlGaN well layer has a thickness of 1 to 10 nm, the AlN barrier layer has a thickness of 2 to 10 nm, and the number of quantum well periods of the long-wavelength quantum well light-emitting layer is 1 to 3;

[0029] The first short-wavelength quantum well light-emitting layer includes an AlGaN / AlN / AlGaN well layer and an AlN barrier layer, wherein the thickness of the AlN barrier layer is 2-10 nm, the thickness of the AlGaN / AlN / AlGaN well layer is 2-8 nm, and the thickness of the AlN layer in the well layer is 0.1-1 nm; the number of quantum well periods in the first short-wavelength quantum well light-emitting layer is 1-3;

[0030] The second short-wavelength quantum well light-emitting layer includes an AlGaN / AlN / AlGaN well layer and an AlN barrier layer, wherein the thickness of the AlN barrier layer is 1-6 nm, the thickness of the AlGaN / AlN / AlGaN well layer is 1-4 nm, and the thickness of the AlN layer in the well layer is 0.1-1.5 nm; the number of quantum well periods of the second short-wavelength quantum well light-emitting layer is 1-3;

[0031] The growth temperature of the long wavelength quantum well light emitting layer is 1000°C to 1100°C, the growth temperature of the first short wavelength quantum well light emitting layer is 1100°C to 1150°C, and the growth temperature of the second short wavelength quantum well light emitting layer is 1100°C to 1150°C.

[0032] Growth temperature is 1150℃~1170℃;

[0033] An electron blocking layer is grown on the quantum well light-emitting layer at a growth temperature of 1100°C to 1200°C and a Mg doping concentration of 1×10 18 ~1×10 19 cm-3 ;

[0034] A P-type AlGaN layer was grown on the electron blocking layer at a growth temperature of 800°C to 1200°C and a Mg doping concentration of 2×10 18 ~1×10 19 cm -3 ;

[0035] Preferably, a P-type ohmic contact layer is grown on the P-type AlGaN layer, wherein the P-type ohmic contact layer is a P-type GaN layer, the growth temperature is 800°C to 1100°C, and the Mg doping concentration is 1×10 19 ~3×10 19 cm -3 ;

[0036] Annealing under an inert atmosphere can produce a multi-wavelength emitting ultraviolet LED.

[0037] The multi-wavelength ultraviolet LED and its preparation method of the present invention have the following advantages over the prior art:

[0038] The multi-wavelength ultraviolet LED of the present invention comprises a quantum well light-emitting layer including at least two quantum well light-emitting layers with different light-emitting wavelengths, and each quantum well light-emitting layer has a different structure and growth temperature. The present invention does not require changing the thickness and composition of the quantum well light-emitting layer to achieve ultraviolet LED light of different wavelengths, but instead achieves light emission of different wavelengths by changing the structure of the potential well layer. By adjusting the thickness of the n-AlN layer in the N-type intensity adjustment layer, thereby affecting the stress of the quantum well light-emitting layer, the relative intensity of ultraviolet light of different wavelengths is adjusted to meet various different application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0040] Figure 1 Schematic diagram of the structure of the multi-wavelength ultraviolet LED of the present invention;

[0041] Figure 2 Schematic diagram of the structure of the quantum well light-emitting layer of the present invention;

[0042] Figure 3 This is an AFM image of the N-type strength adjustment layer in Example 1;

[0043] Figure 4 The hall test data of the N-type strength adjustment layer in Example 1;

[0044] Figure 5 The electroluminescence spectrum of the multi-wavelength UV LED in Example 1;

[0045] Figure 6 Electroluminescence spectrum of the multi-wavelength UV LED in Example 2;

[0046] Figure 7 Electroluminescence spectrum of the multi-wavelength ultraviolet LED in Example 3. DETAILED DESCRIPTION

[0047] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0049] In the description of the present invention, it should be understood that the directions or positions indicated by “upper” and the like are based on the directions or positions shown in the accompanying drawings, or are the directions or positions in which the product of the invention is usually placed when in use, or are the directions or positions commonly understood by those skilled in the art. These directions or positions are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0050] The following are detailed descriptions respectively. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of this application, the term "including" means "including but not limited to". Various embodiments of the present invention may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered ranges, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0051] The present invention provides a multi-wavelength ultraviolet LED, such as Figure 1 As shown, it includes: a substrate 1 and an AlN template layer 2, an AlN thin film layer 3, an N-type strength adjustment layer 4, an n-AlGaN layer 5, a quantum well light-emitting layer 6, an electron blocking layer 7, a P-type AlGaN layer 8 and a P-type ohmic contact layer 9 located on the surface of the substrate 1 and stacked in sequence;

[0052] The quantum well light-emitting layer 6 includes at least two quantum well light-emitting layers with different light-emitting wavelengths.

[0053] In the multi-wavelength ultraviolet LED of the present invention, the quantum well light-emitting layer 6 includes at least two quantum well light-emitting layers with different light-emitting wavelengths, and the structures of each quantum well light-emitting layer are different. The present invention does not need to change the thickness and composition of the quantum well light-emitting layer to achieve ultraviolet LED light of different wavelengths, but instead achieves different ultraviolet light emission wavelengths by changing the structure of the quantum well light-emitting layer. By adjusting the thickness of the n-AlN layer in the N-type intensity adjustment layer 4, the stress of the quantum well light-emitting layer 6 is affected, and the relative intensity of ultraviolet light of different wavelengths is adjusted to meet various different application requirements.

[0054] The multi-wavelength luminescent ultraviolet LED of the present invention has a quantum well luminescent layer 6 structure comprising at least two quantum well luminescent layers with different luminescent wavelengths, and each quantum well luminescent layer has a different structure. The present invention realizes luminescence of different ultraviolet wavelengths through different quantum well structures and different growth conditions, and realizes luminescence of different ultraviolet wavelengths and relative luminescence intensities by adjusting the thickness of the n-AlN layer in the N-type intensity adjustment layer; the quantum well luminescent layer adopts a thin barrier design, which can reduce the barrier height of holes in the barrier region, enhance the tunneling effect of holes, weaken the quantum confinement effect, and make the energy band structure closer to the "flat band" state, which is conducive to promoting the directional transport of holes to the first quantum well. It is conducive to realizing multi-band luminescence of ultraviolet LEDs within 222nm to 350nm. The multi-wavelength luminescent ultraviolet LED of the present invention can realize an effective combination of surface disinfection and air disinfection, and the ultraviolet light source with a wavelength of 222nm has weak penetrating power, which can minimize the impact of irradiation on the human body and has a wider range of applicable scenarios.

[0055] In some embodiments, the N-type strength adjustment layer 4 is n-Al x Ga 1-x N / n-AlN superlattice periodic structure layer; that is, the N-type strength adjustment layer 4 includes n-Al x Ga 1-x N layer, n-AlN layer, and n-Al x Ga 1-x The N layer and the n-AlN layer are arranged alternately in sequence, wherein the thickness of the n-AlN layer is 0.5~10nm, and the thickness of the n-AlN layer is 0.5~10nm. x Ga 1-xThe thickness of N is 5-50 nm, the thickness of the N-type intensity adjustment layer is ≥ 0.5 μm, and 0.7 ≤ x < 1. By adjusting the thickness of the n-AlN layer in the N-type intensity adjustment layer 4, the stress of the quantum well light-emitting layer 6 is affected, and the relative intensity of ultraviolet light of different wavelengths is adjusted.

[0056] In some embodiments, as Figure 2 As shown, the quantum well light emitting layer 6 includes a long wavelength quantum well light emitting layer 61, a first short wavelength quantum well light emitting layer 62, and a second short wavelength quantum well light emitting layer 63 which are stacked in sequence;

[0057] The long-wavelength quantum well light-emitting layer 61 is an AlGaN / AlN quantum well light-emitting layer, namely, an AlGaN well layer 611 and an AlN barrier layer 612. The thickness of the AlGaN well layer 611 is 1-10 nm, the thickness of the AlN barrier layer 612 is 2-10 nm, and the number of quantum well periods of the long-wavelength quantum well light-emitting layer 61 is 1-3.

[0058] The first short wavelength quantum well light emitting layer 62 includes an AlGaN / AlN / AlGaN well layer and an AlN barrier layer, that is, the AlGaN / AlN / AlGaN well layer in the first short wavelength quantum well light emitting layer 62 includes an AlGaN layer, an AlN layer, and an AlGaN layer, which correspond to Figure 2 The AlN barrier layer in the first short wavelength quantum well light emitting layer 62 is numbered 621, 622, and 623. Figure 2 Number 624; the thickness of the AlGaN / AlN / AlGaN well layer in the first short-wavelength quantum well light-emitting layer 62 is 2-8 nm. Further, the thickness of the AlN layer in the AlGaN / AlN / AlGaN well layer is 0.1-1 nm, and the thickness of the AlN barrier layer is 2-10 nm. The number of quantum well periods in the first short-wavelength quantum well light-emitting layer is 1-3. In addition, in the AlGaN / AlN / AlGaN well layer in the first short-wavelength quantum well light-emitting layer 62, the Al content in the two AlGaN layers can be the same or different.

[0059] The second short wavelength quantum well light emitting layer 63 includes an AlGaN / AlN / AlGaN well layer and an AlN barrier layer. The AlGaN / AlN / AlGaN well layer in the second short wavelength quantum well light emitting layer 63 includes an AlGaN layer, an AlN layer, and an AlGaN layer, respectively corresponding to Figure 2 The AlN barrier layer in the second short wavelength quantum well light emitting layer 63 is numbered 631, 632, and 633. Figure 2The AlN barrier layer has a thickness of 1 to 6 nm, the AlGaN / AlN / AlGaN well layer in the second short-wavelength quantum well light-emitting layer 63 has a thickness of 1 to 4 nm, and further, the AlN layer in the AlGaN / AlN / AlGaN well layer has a thickness of 0.1 to 1.5 nm. The second short-wavelength quantum well light-emitting layer 63 has a quantum well period number of 1 to 3. Furthermore, the Al content in the two AlGaN layers in the AlGaN / AlN / AlGaN well layer in the first short-wavelength quantum well light-emitting layer 63 can be the same or different.

[0060] In some embodiments, the n-AlGaN layer 5 includes n-AlGaN layers stacked in sequence. y Ga 1-y N layer, n-Al z Ga 1-z N-layer;

[0061] n-Al y Ga 1-y The thickness of the N layer is 200~1000nm;

[0062] n-Al z Ga 1-z The thickness of the N layer is 0.1~100nm;

[0063] Among them, 0.7≤y≤x≤z<1.

[0064] In some embodiments, the electron blocking layer 7 is a P-AlGaN layer, and the P-AlGaN layer is a P-Al a Ga 1-a N layer, 0.8≤a<1, the thickness of the electron blocking layer 7 is 0.5~50nm.

[0065] In some embodiments, the thickness of the P-type AlGaN layer 8 is 50-500 nm, and the P-type AlGaN layer is P-Al b Ga 1-b N layers, 0.5≤b<1.

[0066] In some embodiments, the P-type ohmic contact layer 9 is a P-type GaN layer with a thickness of 0.5-50 nm.

[0067] Specifically, from the P-type AlGaN layer 8 to the P-type GaN layer, the Al composition gradually changes from 0.8 to 1 to 0, and the Al element changes from being present to being absent.

[0068] In some embodiments, the thickness of the AlN thin film layer 3 is 50 nm to 500 nm.

[0069] In some embodiments, the growth temperature of the long-wavelength quantum well light-emitting layer 61 is T1, the growth temperature of the first short-wavelength quantum well light-emitting layer 62 is T2, and the growth temperature of the second short-wavelength quantum well light-emitting layer 63 is T3.

[0070] Where 1000°C ≤ T1 < T2 < T3 ≤ 1170°C.

[0071] In some embodiments, the substrate 1 includes any one of a sapphire substrate, a silicon carbide substrate, a silicon substrate, a GaN substrate, and an AlN substrate.

[0072] For the multi-wavelength light-emitting ultraviolet LED of the present invention, the structure of the quantum well light-emitting layer 6 includes at least two quantum well light-emitting layers with different light-emitting wavelengths, and the structures of each quantum well light-emitting layer are different; further, the quantum well light-emitting layer 6 includes a long-wavelength quantum well light-emitting layer 61, a first short-wavelength quantum well light-emitting layer 62, and a second short-wavelength quantum well light-emitting layer 63 stacked in sequence. The growth temperature of the long-wavelength quantum well light-emitting layer 61 is T1, the growth temperature of the first short-wavelength quantum well light-emitting layer 62 is T2, and the growth temperature of the second short-wavelength quantum well light-emitting layer 63 is T3, where 1000°C ≤ T1 < T2 < T3 ≤ 1170°C; the present invention realizes different ultraviolet light-emitting wavelengths through different structures of the quantum well light-emitting layer 及不同的生长温度实现不同的紫外光发光波长,通过调节N型强度调节层中的n-AlN层的厚度,实现不同的紫外光发光相对强度。利用该外延技术可以实现对物表消杀功能(222nm)和空气消杀的有效组合,222nm紫外光源穿透力弱,可以将照射对人体的影响降到最低,适用场景更广泛。

[0073] Based on the same inventive concept, the present invention also provides a preparation method of the above multi-wavelength light-emitting ultraviolet LED, including the following steps:

[0074] Prepare an AlN template layer 2 on the substrate 1, and sequentially grow an AlN thin film layer 3, an N-type intensity adjustment layer 4, an n-AlGaN layer 5, a quantum well light-emitting layer, an electron blocking layer 7, a P-type AlGaN layer 8, and a P-type ohmic contact layer 9 on the AlN template layer.

[0075] In some embodiments, the AlN thin film layer, the AlN template layer, and the AlN layer are deposited with ammonia gas and an aluminum source as raw materials. The aluminum source is preferably an organoaluminum compound, more preferably trimethylaluminum, and is deposited by MOCVD (metalorganic chemical vapor deposition).

[0076] In some embodiments, the n-AlGaN layer, n-Al x Ga 1-xThe N layer is grown using TMAl (trimethylaluminum), TMGa (trimethylgallium) and NH3 (ammonia) as Al source, Ga source and N source respectively, and SiH4 (monosilane) as a doping source.

[0077] In some embodiments, the n-AlN layer is grown using TMAl (trimethylaluminum) and NH 3 as Al and N sources, respectively, and SiH 4 as a doping source.

[0078] In some embodiments, the AlGaN layer is grown using TMAl (trimethylaluminum), TMGa (trimethylgallium), and NH 3 as Al source, Ga source, and N source, respectively.

[0079] In some embodiments, the P-type GaN layer is grown using TMGa (trimethylgallium) and NH 3 as Ga and N sources, respectively, and biscyclopentadienyl magnesium (Cp 2 Mg) as a doping source.

[0080] In some embodiments, the P-AlGaN layer is grown using TMAl (trimethylaluminum), TMGa (trimethylgallium), and NH 3 as Al, Ga, and N sources, respectively, and biscyclopentadienylmagnesium (Cp 2 Mg) as a doping source.

[0081] In some embodiments, a method for preparing a multi-wavelength ultraviolet LED comprises the following steps:

[0082] S1. Growing an AlN thin film layer on a substrate containing an AlN template layer. Specifically, the AlN thin film layer is deposited using metal organic chemical vapor deposition (MOCVD), with TMAl (trimethylaluminum) or TEAl (triethylaluminum) being used as the Al source, NH3 being used as the nitrogen source, and H2 being used as the carrier gas. The AlN thin film layer growth temperature is controlled between 1100°C and 1300°C, and the pressure is controlled between 30 and 100 mbar, ultimately obtaining a high-quality AlN thin film layer with a smooth surface.

[0083] S2, growing an N-type strength adjustment layer on the AlN thin film layer, the N-type strength adjustment layer is n-Al x Ga 1-x N / n-AlN superlattice periodic structure layer, 0.7≤x<1, N-type strength adjustment layer carrier concentration is 5×10 17 ~1×10 19 cm -3 Specifically, the N-type strength adjustment layer is formed by MOCVD deposition, with TMAl or TEAl as the Al source, TMGa (trimethyl gallium) or TEGa (triethyl gallium) as the Ga source, NH3 as the nitrogen source, SiH4 as the doping source, and H2 as the carrier gas. The growth temperature is controlled between 1000°C and 1200°C, and the pressure is controlled between 30 and 100 mbar.

[0084] S3, growing an n-AlGaN layer on the N-type strength adjustment layer, the n-AlGaN layer includes sequentially stacked n-Al y Ga 1-y N layer, n-Al z Ga 1-z N layer, in which n-Al y Ga 1-y The thickness of the N layer is 0.2~1μm, the growth temperature is 1000℃~1200℃, and the carrier concentration is 1×10 18 ~1×10 19 cm -3 ; n-Al z Ga 1-z The thickness of the N layer is 0.1~100nm, the growth temperature is 1000℃~1200℃, and the carrier concentration is 1×10 17 ~1×10 18 cm -3 , wherein 0.7≤y≤x≤z<1, and more preferably, 0.75≤y≤z≤0.9; specifically, the n-AlGaN layer is deposited by MOCVD, TMAl or TEAl is selected as the Al source, TMGa (trimethyl gallium) or TEGa (triethyl gallium) is selected as the Ga source, NH3 is used as the nitrogen source, SiH4 is used as the doping source, H2 is used as the carrier gas, and the pressure is controlled between 30 and 100 mbar;

[0085] S4. Growing a quantum well light-emitting layer on the n-AlGaN layer; the quantum well light-emitting layer includes a long-wavelength quantum well light-emitting layer, a first short-wavelength quantum well light-emitting layer, and a second short-wavelength quantum well light-emitting layer stacked in sequence; wherein the long-wavelength quantum well light-emitting layer is an AlGaN / AlN quantum well light-emitting layer, the thickness of the AlGaN well layer is 1-10 nm, the thickness of the AlN barrier layer is 2-10 nm, and the number of quantum well periods of the long-wavelength quantum well light-emitting layer is 1-3; specifically, MOCVD deposition is used to obtain the long-wavelength quantum well light-emitting layer, TMAl or TEAl is selected as the Al source, TMGa (trimethyl gallium) or TEGa (triethyl gallium) is selected as the Ga source, NH3 is used as the nitrogen source, H2 is used as the carrier gas, and the pressure is controlled between 30 and 100 mbar;

[0086] The first short-wavelength quantum well light-emitting layer includes an AlGaN / AlN / AlGaN well layer and an AlN barrier layer. The thickness of the AlN barrier layer is 2-10 nm, the thickness of the AlGaN / AlN / AlGaN well layer is 2-8 nm, and the thickness of the AlN layer in the well layer is 0.1-1 nm. The number of quantum well periods in the first short-wavelength quantum well light-emitting layer is 1-3.

[0087] The second short-wavelength quantum well light-emitting layer includes an AlGaN / AlN / AlGaN well layer and an AlN barrier layer. The thickness of the AlN barrier layer is 1-6 nm, the thickness of the AlGaN / AlN / AlGaN well layer is 1-4 nm, and the thickness of the AlN layer in the well layer is 0.1-1.5 nm. The number of quantum well periods in the second short-wavelength quantum well light-emitting layer is 1-3.

[0088] The growth temperature of the long-wavelength quantum well light-emitting layer is 1000° C. to 1100° C., the growth temperature of the first short-wavelength quantum well light-emitting layer is 1100° C. to 1150° C., and the growth temperature of the second short-wavelength quantum well light-emitting layer is 1150° C. to 1170° C.;

[0089] S5. An electron blocking layer with a thickness of 0.1-50 nm is grown on the quantum well light-emitting layer. Specifically, the electron blocking layer is obtained by MOCVD deposition, TMAl or TEAl is selected as the Al source, TMGa (trimethyl gallium) or TEGa (triethyl gallium) is selected as the Ga source, NH3 is selected as the nitrogen source, MgCp2 (bis(cyclopentadienyl)magnesium) is selected as the doping source, H2 is selected as the carrier gas, the pressure is controlled between 50-200 mbar, the growth temperature is 1100℃-1200℃, and the Mg doping concentration is 1×10 18 ~1×10 19 cm -3 ;

[0090] S6. A P-type AlGaN layer with a thickness of 50-500 nm is grown on the electron blocking layer. Specifically, the P-type AlGaN layer is obtained by MOCVD deposition, TMAl or TEAl is selected as the Al source, TMGa (trimethyl gallium) or TEGa (triethyl gallium) is selected as the Ga source, NH3 is selected as the nitrogen source, MgCp2 (bis(cyclopentadienyl)magnesium) is selected as the doping source, H2 is used as the carrier gas, the pressure is controlled between 50-200 mbar, the growth temperature is 800℃-1200℃, and the Mg doping concentration is 2×10 18 ~1×10 19 cm -3 ;

[0091] S7. A P-type ohmic contact layer with a thickness of 0.1-50 nm is grown on the P-type AlGaN layer. The P-type ohmic contact layer is a P-type GaN layer. Specifically, the P-type GaN layer is obtained by MOCVD deposition. TMGa (trimethyl gallium) or TEGa (triethyl gallium) is selected as the Ga source, NH3 is used as the nitrogen source, MgCp2 (bis(cyclopentadienyl)magnesium) is used as the doping source, H2 is used as the carrier gas, the pressure is controlled between 100-500 mbar, the growth temperature is 800℃-1100℃, and the Mg doping concentration is 1×10 19 ~3×10 19 cm -3 .

[0092] S8. Annealing is performed under an inert atmosphere to obtain a multi-wavelength emitting ultraviolet LED.

[0093] In some embodiments, the annealing temperature is 700° C. to 900° C., and the annealing time is 10 min to 40 min.

[0094] In some embodiments, the inert atmosphere includes any one of nitrogen, helium, neon, argon, and the like.

[0095] In some embodiments, before depositing each layer on the substrate, the substrate is further treated. Specifically, the treatment includes: cleaning the surface of the substrate using a mixed atmosphere of hydrogen and ammonia at a temperature of 700° C. to 950° C.

[0096] The following further illustrates the multi-wavelength ultraviolet LED and its preparation method of the present application with specific examples. This section further illustrates the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0097] Example 1

[0098] The present invention provides a multi-wavelength ultraviolet LED, comprising: a sapphire substrate and an AlN template layer, an AlN thin film layer, an N-type intensity adjustment layer, an n-AlGaN layer, a quantum well light-emitting layer, an electron blocking layer, a P-type AlGaN layer, and a P-type ohmic contact layer, which are stacked in sequence on the surface of the substrate;

[0099] The thickness of the AlN template layer is 500 nm;

[0100] The thickness of the AlN film layer is 50 nm;

[0101] N-type strength adjustment layer is n-Al 0.8 Ga 0.2 N / n-AlN superlattice periodic structure layer, the thickness of n-AlN layer is 2nm, the thickness of n-Al 0.8 Ga 0.2 The thickness of N is 18 nm, the total thickness of the N-type strength adjustment layer is 800 nm, and the carrier concentration of the N-type strength adjustment layer is 5×10 17 cm -3 ;

[0102] The n-AlGaN layer includes n-Al 0.8 Ga 0.2 N layer, n-Al 0.85 Ga 0.15 N layer; n-Al 0.8 Ga0.2 The thickness of the N layer is 200 nm and the carrier concentration is 1×10 18 cm -3 ; n-Al 0.85 Ga 0.15 The thickness of the N layer is 20 nm and the carrier concentration is 3×10 17 cm -3 ;

[0103] The quantum well light emitting layer includes a long wavelength quantum well light emitting layer, a first short wavelength quantum well light emitting layer, and a second short wavelength quantum well light emitting layer stacked in sequence;

[0104] The long wavelength quantum well light emitting layer is Al 0.3 Ga 0.7 N / AlN quantum well light-emitting layer, Al 0.3 Ga 0.7 The thickness of the N well layer is 2nm, the thickness of the AlN barrier layer is 3nm, and the number of quantum well periods in the long wavelength quantum well light-emitting layer is 2;

[0105] The first short-wavelength quantum well light-emitting layer includes Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 N well layer, AlN barrier layer, AlN barrier layer thickness is 2.5nm, Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 The thicknesses of the N-well layers are 1nm / 0.5nm / 1nm respectively, and the number of quantum well periods of the first short-wavelength quantum well light-emitting layer is 2;

[0106] The second short-wavelength quantum well light-emitting layer includes Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 N well layer, AlN barrier layer, AlN barrier layer thickness is 3nm, Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 The thickness of the N-well layer is 0.5nm / 1nm0.5nm respectively, and the number of quantum well periods of the second short-wavelength quantum well light-emitting layer is 2;

[0107] The electron blocking layer is P-Al 0.85 Ga 0.15 The thickness of the N layer and electron blocking layer is 10 nm, and the Mg doping concentration is 1×10 18 ;

[0108] The P-type AlGaN layer is P-Al 0.6 Ga0.4 N layer, thickness 50nm, Mg doping concentration 2×10 18 ;

[0109] The P-type ohmic contact layer is a P-type GaN layer with a thickness of 20 nm and a Mg doping concentration of 1×10 19 ;

[0110] The method for preparing the multi-wavelength ultraviolet LED comprises the following steps:

[0111] S1. Select a sapphire substrate containing an AlN template layer and clean the surface of the template substrate using a mixed atmosphere of hydrogen and ammonia at a temperature of 900°C for 20 minutes.

[0112] S2. Growing an AlN thin film layer with a thickness of 50 nm on the AlN template layer; selecting TMAl (trimethylaluminum) as the Al source, NH3 as the nitrogen source, and H2 as the carrier gas; controlling the AlN thin film growth temperature at 1100°C, the pressure at 50 mbar, and the V / III ratio at 200 (i.e., the flow ratio of ammonia to trimethylaluminum is 200), ultimately obtaining a high-quality AlN thin film layer with a smooth surface;

[0113] S3, growing an N-type strength adjustment layer on the AlN thin film layer, the N-type strength adjustment layer is n-Al 0.8 Ga 0.2 N / n-AlN superlattice periodic structure layer, the thickness of n-AlN layer is 2nm, the thickness of n-Al 0.8 Ga 0.2 The thickness of N is 18nm, and the total thickness of the N-type strength adjustment layer is 800nm; 0.8 Ga 0.2 The growth temperature of N / n-AlN was 1050℃, TMAl was selected as Al source, TMGa as Ga source, NH3 as nitrogen source, SiH4 as doping source, H2 as carrier gas, and the pressure was controlled at 60mbar. The carrier concentration of N-type strength adjustment layer was 5×10 17 ;

[0114] S4, growing an n-AlGaN layer on the N-type strength adjustment layer, the n-AlGaN layer includes sequentially stacked n-Al 0.8 Ga 0.2 N layer, n-Al 0.85 Ga 0.15 N layer; n-Al 0.8 Ga 0.2 The thickness of the N layer is 200 nm, the growth temperature is 1050 ° C, and the carrier concentration is 1 × 10 18 ; n-Al 0.85 Ga 0.15The thickness of the N layer is 20 nm, the growth temperature is 1070 ° C, and the carrier concentration is 3 × 10 17 ; TMA was selected as the Al source, TMGa as the Ga source, NH3 as the nitrogen source, SiH4 as the doping source, H2 as the carrier gas, and the pressure was controlled at 60 mba;

[0115] S5. sequentially growing a long-wavelength quantum well light-emitting layer, a first short-wavelength quantum well light-emitting layer, and a second short-wavelength quantum well light-emitting layer on the n-AlGaN layer;

[0116] The long wavelength quantum well light emitting layer is Al 0.3 Ga 0.7 N / AlN quantum well light-emitting layer, Al 0.3 Ga 0.7 The thickness of the N well layer is 2nm, the thickness of the AlN barrier layer is 3nm, and the number of quantum well periods of the long wavelength quantum well light emitting layer is 2; 0.3 Ga 0.7 The growth temperature of N / AlN was 1070℃, TMAl was used as Al source, TMGa was used as Ga source, NH3 was used as nitrogen source, H2 was used as carrier gas, and the pressure was controlled between 60mbar.

[0117] The first short-wavelength quantum well light-emitting layer includes Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 N well layer, AlN barrier layer, AlN barrier layer thickness is 2.5nm, Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 The thickness of the N-well layer is 1nm / 0.5nm / 1nm respectively; the number of quantum well periods of the first short-wavelength quantum well light-emitting layer is 2; 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 The growth temperature of the N well layer and the AlN barrier layer was 1120°C. TMAl was used as the Al source, TMGa as the Ga source, NH3 as the nitrogen source, and H2 as the carrier gas, with the pressure controlled at 60 mbar.

[0118] The second short-wavelength quantum well light-emitting layer includes Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 N well layer, AlN barrier layer, AlN barrier layer thickness is 3nm, Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4The thickness of the N-well layer is 0.5nm / 1nm0.5nm respectively, and the number of quantum well periods of the second short-wavelength quantum well light-emitting layer is 2; 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 The growth temperature of the N well layer and the AlN barrier layer is 1150℃, TMAl is selected as the Al source, TMGa is used as the Ga source, NH3 is used as the nitrogen source, H2 is used as the carrier gas, and the pressure is controlled at 60mbar;

[0119] S6, growing an electron blocking layer on the second short-wavelength quantum well light-emitting layer, the electron blocking layer is P-Al 0.85 Ga 0.15 The thickness of the N layer and electron blocking layer is 10 nm, and the Mg doping concentration is 1×10 18 , select TMAl as Al source, TMG as Ga source, NH3 as nitrogen source, MgCp2 as doping source, H2 as carrier gas, pressure controlled at 100 mbar, growth temperature at 1100 ℃;

[0120] S7, grow a 50nm thick P-Al layer on the electron blocking layer 0.6 Ga 0.4 N layer, Mg doping concentration 2×10 18 ; TMAl was selected as the Al source, TMGa as the Ga source, NH3 as the nitrogen source, MgCp2 as the doping source, H2 as the carrier gas, the pressure was controlled at 100 mbar, and the growth temperature was 1100°C;

[0121] S8, grow a P-type ohmic contact layer on the P-type AlGaN layer, which is a P-type GaN layer with a thickness of 20 nm and a Mg doping concentration of 1×10 19 TMGa was selected as the Ga source, NH3 as the nitrogen source, MgCp2 as the doping source, H2 as the carrier gas, the pressure was controlled at 120 mbar, and the growth temperature was 900°C.

[0122] S9. Annealing in a nitrogen environment at a temperature of 900° C. for 10 min.

[0123] Example 2

[0124] The wavelength emitting ultraviolet LED provided in this embodiment is the same as that in embodiment 1, except that the N-type intensity adjustment layer is n-Al 0.8 Ga 0.2 N / n-AlN superlattice periodic structure layer, the thickness of n-AlN layer is 0.5nm, the thickness of n-Al 0.8 Ga 0.2 The thickness of N is 19.5 nm, the total thickness of the N-type strength adjustment layer is 1000 nm, and the carrier concentration of the N-type strength adjustment layer is 3×1018 cm -3 ;

[0125] The method for preparing a wavelength emitting ultraviolet LED in Example 2 is the same as that in Example 1, except that step S3 is: growing an N-type intensity adjustment layer on the AlN thin film layer, and the N-type intensity adjustment layer is n-Al 0.8 Ga 0.2 N / n-AlN superlattice periodic structure layer, the thickness of n-AlN layer is 0.5nm, the thickness of n-Al 0.8 Ga 0.2 The thickness of N is 19.5 nm, the total thickness of the N-type strength adjustment layer is 1000 nm, the growth temperature is 1100 °C, and the carrier concentration of the N-type strength adjustment layer is 3×10 18 cm -3 ; The rest are the same as in Example 1.

[0126] Example 3

[0127] The present invention provides a multi-wavelength ultraviolet LED, comprising: a sapphire substrate and an AlN template layer, an AlN thin film layer, an N-type intensity adjustment layer, an n-AlGaN layer, a quantum well light-emitting layer, an electron blocking layer, a P-type AlGaN layer, and a P-type ohmic contact layer, which are stacked in sequence on the surface of the substrate;

[0128] The thickness of the AlN template layer is 500 nm;

[0129] The thickness of the AlN film layer is 500 nm;

[0130] N-type strength adjustment layer is n-Al 0.8 Ga 0.2 N / n-AlN superlattice periodic structure layer, the thickness of n-AlN layer is 0.5nm, the thickness of n-Al 0.8 Ga 0.2 The thickness of N is 14.5 nm, the total thickness of the N-type strength adjustment layer is 1005 nm, and the carrier concentration of the N-type strength adjustment layer is 1×10 18 cm -3 ;

[0131] The n-AlGaN layer includes n-Al 0.8 Ga 0.2 N layer, n-Al 0.85 Ga 0.15 N layer; n-Al 0.8 Ga 0.2 The thickness of the N layer is 300 nm and the carrier concentration is 1×10 18 cm -3 ; n-Al 0.85 Ga 0.15The thickness of the N layer is 50 nm and the carrier concentration is 1×10 17 cm -3 ;

[0132] The quantum well light emitting layer includes a long wavelength quantum well light emitting layer and a first short wavelength quantum well light emitting layer stacked in sequence;

[0133] The long wavelength quantum well light emitting layer is Al 0.65 Ga 0.45 N / AlN quantum well light-emitting layer, Al 0.65 Ga 0.45 The thickness of the N well layer is 2nm, the thickness of the AlN barrier layer is 4nm, and the number of quantum well periods in the long wavelength quantum well light-emitting layer is 2;

[0134] The first short-wavelength quantum well light-emitting layer includes Al 0.65 Ga 0.45 N / AlN / Al 0.65 Ga 0.45 N well layer, AlN barrier layer, AlN barrier layer thickness is 4nm, Al 0.65 Ga 0.45 N / AlN / Al 0.65 Ga 0.45 The thickness of the N-well layer is 1nm / 1nm / 1nm respectively, and the number of quantum well periods of the first short-wavelength quantum well light-emitting layer is 3;

[0135] The electron blocking layer is P-Al 0.8 Ga 0.2 The thickness of the N layer and electron blocking layer is 1 nm, and the Mg doping concentration is 1×10 18 ;

[0136] The P-type AlGaN layer is P-Al 0.6 Ga 0.4 N layer, thickness 100nm, Mg doping concentration 2×10 18 ;

[0137] The P-type ohmic contact layer is a P-type GaN layer with a thickness of 20 nm and a Mg doping concentration of 1×10 19 ;

[0138] The method for preparing the multi-wavelength ultraviolet LED comprises the following steps:

[0139] S1. Select a sapphire substrate containing an AlN template layer and clean the surface of the template substrate using a mixed atmosphere of hydrogen and ammonia at a temperature of 900°C for 5 minutes.

[0140] S2. Growing an AlN thin film layer with a thickness of 500 nm on the AlN template layer; selecting TMAl (trimethylaluminum) as the Al source, NH3 as the nitrogen source, and H2 as the carrier gas; controlling the AlN thin film growth temperature at 1250°C, the pressure at 50 mbar, and the V / III ratio at 100 (i.e., the flow ratio of ammonia to trimethylaluminum is 100), ultimately obtaining a high-quality AlN thin film layer with a smooth surface;

[0141] S3, growing an N-type strength adjustment layer on the AlN thin film layer, the N-type strength adjustment layer is n-Al 0.8 Ga 0.2 N / n-AlN superlattice periodic structure layer, the thickness of n-AlN layer is 0.5nm, the thickness of n-Al 0.8 Ga 0.2 The thickness of N is 14.5 nm, the total thickness of the N-type strength adjustment layer is 1005 nm, and the carrier concentration of the N-type strength adjustment layer is 1×10 18 cm -3 ; n-Al 0.8 Ga 0.2 The growth temperature of N / n-AlN was 1150℃, TMAl was used as Al source, TMGa as Ga source, NH3 as nitrogen source, SiH4 as doping source, H2 as carrier gas, and the pressure was controlled at 60mbar.

[0142] S4, growing an n-AlGaN layer on the N-type strength adjustment layer, the n-AlGaN layer includes sequentially stacked n-Al 0.8 Ga 0.2 N layer, n-Al 0.85 Ga 0.15 N layer; n-Al 0.8 Ga 0.2 The thickness of the N layer is 300 nm, the growth temperature is 1050 ° C, and the carrier concentration is 1 × 10 18 cm -3 ; n-Al 0.85 Ga 0.15 The thickness of the N layer is 50 nm, the growth temperature is 1070 ° C, and the carrier concentration is 1 × 10 17 cm -3 ; TMA was selected as the Al source, TMGa as the Ga source, NH3 as the nitrogen source, SiH4 as the doping source, H2 as the carrier gas, and the pressure was controlled at 60 mba;

[0143] S5. sequentially growing a long-wavelength quantum well light-emitting layer and a first short-wavelength quantum well light-emitting layer on the n-AlGaN layer;

[0144] The long wavelength quantum well light emitting layer is Al 0.65 Ga 0.45 N / AlN quantum well light-emitting layer, Al0.65 Ga 0.45 The thickness of the N well layer is 2nm, the thickness of the AlN barrier layer is 4nm, and the number of quantum well periods of the long wavelength quantum well light emitting layer is 2; 0.65 Ga 0.45 The growth temperature of N / AlN was 1040℃, TMAl was used as Al source, TMGa was used as Ga source, NH3 was used as nitrogen source, H2 was used as carrier gas, and the pressure was controlled between 60mbar;

[0145] The first short-wavelength quantum well light-emitting layer includes Al 0.65 Ga 0.45 N / AlN / Al 0.65 Ga 0.45 N well layer, AlN barrier layer, AlN barrier layer thickness is 4nm, Al 0.65 Ga 0.45 N / AlN / Al 0.65 Ga 0.45 The thickness of the N-well layer is 1nm / 1nm / 1nm respectively, and the number of quantum well periods of the first short-wavelength quantum well light-emitting layer is 3; 0.65 Ga 0.45 N / AlN / Al 0.65 Ga 0.45 The growth temperature of the N well layer and the AlN barrier layer is 1150℃, TMAl is selected as the Al source, TMGa is used as the Ga source, NH3 is used as the nitrogen source, H2 is used as the carrier gas, and the pressure is controlled at 60mbar;

[0146] S6, growing an electron blocking layer on the second short-wavelength quantum well light-emitting layer, the electron blocking layer is P-Al 0.8 Ga 0.2 The thickness of the N layer and electron blocking layer is 1 nm, and the Mg doping concentration is 1×10 18 , select TMAl as Al source, TMG as Ga source, NH3 as nitrogen source, MgCp2 as doping source, H2 as carrier gas, pressure controlled at 100 mbar, growth temperature at 1120℃;

[0147] S7, growing a 100nm thick P-Al layer on the electron blocking layer 0.6 Ga 0.4 N layer, Mg doping concentration 2×10 18 TMAl was selected as the Al source, TMGa as the Ga source, NH3 as the nitrogen source, MgCp2 as the doping source, H2 as the carrier gas, the pressure was controlled at 100 mbar, and the growth temperature was 980°C.

[0148] S8, in P-Al 0.6 Ga 0.4A P-type ohmic contact layer is grown on the N layer. The P-type ohmic contact layer is a P-type GaN layer with a thickness of 20 nm and a Mg doping concentration of 1×10 19 TMGa was selected as the Ga source, NH3 as the nitrogen source, MgCp2 as the doping source, H2 as the carrier gas, the pressure was controlled at 120 mbar, and the growth temperature was 950°C.

[0149] S9. Annealing in a nitrogen environment at a temperature of 900° C. for 10 min.

[0150] Figure 3 This is an AFM image of the N-type strength adjustment layer in Example 1;

[0151] Figure 4 The hall test data of the N-type strength adjustment layer in Example 1;

[0152] Figure 5 Electroluminescence spectrum of the multi-wavelength ultraviolet LED in Example 1.

[0153] Figure 6 Electroluminescence spectrum of the multi-wavelength ultraviolet LED in Example 2.

[0154] Figure 7 Electroluminescence spectrum of the multi-wavelength ultraviolet LED in Example 3.

[0155] from Figure 3 It can be seen that the N-type strength adjustment layer n-Al in Example 1 0.8 Ga 0.2 The surface of N / n-AlN is smooth; Figure 4 It can be seen that the N-type strength adjustment layer n-Al in Example 1 0.8 Ga 0.2 N / n-AlN can achieve n-type doping.

[0156] from Figure 5 It can be seen that in the multi-wavelength luminescent ultraviolet LED in Example 1, the ultraviolet light wavelengths emitted by the long-wavelength quantum well light-emitting layer, the first short-wavelength quantum well light-emitting layer, and the second short-wavelength quantum well light-emitting layer are 314 nm, 251 nm, and 223 nm, respectively, among which the short-wavelength ultraviolet light with a wavelength of 251 nm has the strongest intensity.

[0157] from Figures 6 and 7 It can be seen from the figure that the multi-wavelength ultraviolet LED of the present invention can realize multi-wavelength ultraviolet LED light emission, and the change of the intensity of different light emission wavelengths is achieved through the intensity adjustment layer.

[0158] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-wavelength ultraviolet LED, characterized in that: The method comprises a substrate and an AlN template layer, an AlN thin film layer, an N-type strength adjustment layer, an n-AlGaN layer, a quantum well light-emitting layer, an electron blocking layer, a P-type AlGaN layer and a P-type ohmic contact layer, which are located on the surface of the substrate and stacked in sequence. Wherein, the quantum well light-emitting layer includes at least two quantum well light-emitting layers with different light-emitting wavelengths; The N-type strength adjustment layer is n-Al x Ga 1-x N / n-AlN superlattice periodic structure layer; the thickness of n-AlN is 0.5~2nm, and the thickness of n-Al x Ga 1-x The thickness of N is 5-50 nm, the thickness of the N-type strength adjustment layer is ≥0.5 μm, and 0.7≤x<1; The quantum well light-emitting layer comprises a long wavelength quantum well light-emitting layer, a first short wavelength quantum well light-emitting layer, and a second short wavelength quantum well light-emitting layer stacked in sequence; Wherein, the long wavelength quantum well light emitting layer is Al 0.3 Ga 0.7 N / AlN quantum well light-emitting layer, Al 0.3 Ga 0.7 The thickness of the N well layer is 2nm, the thickness of the AlN barrier layer is 3nm, and the number of quantum well periods in the long wavelength quantum well light-emitting layer is 2; The first short-wavelength quantum well light-emitting layer includes Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 N well layer, AlN barrier layer, AlN barrier layer thickness is 2.5nm, Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 The thicknesses of the N-well layers are 1nm / 0.5nm / 1nm respectively, and the number of quantum well periods of the first short-wavelength quantum well light-emitting layer is 2; The second short-wavelength quantum well light-emitting layer includes Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 N well layer, AlN barrier layer, AlN barrier layer thickness is 3nm, Al 0.6 Ga 0.4 N / AlN / Al 0.6 Ga 0.4 The thicknesses of the N-well layers are 0.5nm / 1nm / 0.5nm respectively, and the number of quantum well periods of the second short-wavelength quantum well light-emitting layer is 2; The n-AlGaN layer includes n-Al y Ga 1-y N layer, n-Al z Ga 1-z N-layer; Wherein 0.7≤y≤x≤z<1; the electron blocking layer is a P-AlGaN layer, and the P-AlGaN layer is a P-Al a Ga 1-a N layers, 0.8≤a<1; The P-type AlGaN layer is P-Al b Ga 1-b N layers, 0.5≤b<1; The P-type ohmic contact layer is a P-type GaN layer; The growth temperature of the long wavelength quantum well light emitting layer is 1000°C to 1100°C, the growth temperature of the first short wavelength quantum well light emitting layer is 1100°C to 1150°C, and the growth temperature of the second short wavelength quantum well light emitting layer is 1100°C to 1150°C. The growth temperature is 1150℃~1170℃.

2. The multi-wavelength ultraviolet LED according to claim 1, wherein: The n-Al y Ga 1-y The thickness of the N layer is 200~1000nm; The n-Al z Ga 1-z The thickness of the N layer is 0.1~100nm.

3. The multi-wavelength ultraviolet LED according to claim 1, wherein: The thickness of the electron blocking layer is 0.5~50nm.

4. The multi-wavelength ultraviolet LED according to claim 1, wherein: The thickness of the P-type AlGaN layer is 50-500 nm.

5. The multi-wavelength ultraviolet LED according to claim 1, wherein: The thickness of the P-type ohmic contact layer is 0.5-50 nm; The thickness of the AlN thin film layer is 50nm to 500nm.

6. A method for preparing a multi-wavelength ultraviolet LED according to any one of claims 1 to 5, characterized in that: The following steps are involved: An AlN template layer, an AlN thin film layer, an N-type strength adjustment layer, an n-AlGaN layer, a quantum well light-emitting layer, an electron blocking layer, a P-type AlGaN layer and a P-type ohmic contact layer are sequentially grown on the substrate; The growth temperature of the long wavelength quantum well light emitting layer is 1000°C to 1100°C, the growth temperature of the first short wavelength quantum well light emitting layer is 1100°C to 1150°C, and the growth temperature of the second short wavelength quantum well light emitting layer is 1100°C to 1150°C. The growth temperature is 1150℃~1170℃.

7. The method for preparing a multi-wavelength ultraviolet LED according to claim 6, wherein: An AlN template layer is grown on a substrate, and an AlN thin film layer is grown on the AlN template layer; the AlN thin film layer growth temperature is 1100° C. to 1300° C.; An N-type strength adjustment layer is grown on the AlN thin film layer. The N-type strength adjustment layer is n-Al x Ga 1-x N / n-AlN superlattice periodic structure layer, growth temperature 1000℃~1200℃, carrier concentration 5×10 17 ~1×10 19 cm -3 ; An n-AlGaN layer is grown on the N-type strength adjustment layer, wherein the n-AlGaN layer comprises n-Al y Ga 1-y N layer, n-Al z Ga 1-z N layer, in which n-Al y Ga 1-y The thickness of the N layer is 0.2~1μm, the growth temperature is 1000℃~1200℃, and the carrier concentration is 1×10 18 ~1×10 19 cm -3 ; n-Al z Ga 1-z The thickness of the N layer is 0.1~100nm, the growth temperature is 1000℃~1200℃, and the carrier concentration is 1×10 17 ~1×10 18 cm -3 ; A quantum well light-emitting layer is grown on the n-AlGaN layer; the quantum well light-emitting layer comprises a long-wavelength quantum well light-emitting layer, a first short-wavelength quantum well light-emitting layer, and a second short-wavelength quantum well light-emitting layer stacked in sequence; wherein the long-wavelength quantum well light-emitting layer is an AlGaN / AlN quantum well light-emitting layer, the AlGaN well layer has a thickness of 2 nm, the AlN barrier layer has a thickness of 3 nm, and the number of quantum well periods of the long-wavelength quantum well light-emitting layer is 2; The first short-wavelength quantum well light-emitting layer includes an AlGaN / AlN / AlGaN well layer and an AlN barrier layer. The AlN barrier layer has a thickness of 2.5 nm, and the AlGaN / AlN / AlGaN well layer has a thickness of 1 nm / 0.5 nm / 1 nm, respectively. The number of quantum well periods in the first short-wavelength quantum well light-emitting layer is 2. The second short-wavelength quantum well light-emitting layer includes an AlGaN / AlN / AlGaN well layer and an AlN barrier layer, the AlN barrier layer has a thickness of 3 nm, the AlGaN / AlN / AlGaN well layer has a thickness of 0.5 nm / 1 nm / 0.5 nm, and the second short-wavelength quantum well light-emitting layer has a quantum well period number of 2; The growth temperature of the long wavelength quantum well light emitting layer is 1000°C to 1100°C, the growth temperature of the first short wavelength quantum well light emitting layer is 1100°C to 1150°C, and the growth temperature of the second short wavelength quantum well light emitting layer is 1100°C to 1150°C. Growth temperature is 1150℃~1170℃; An electron blocking layer is grown on the quantum well light-emitting layer at a growth temperature of 1100°C to 1200°C and a Mg doping concentration of 1×10 18 ~1×10 19 cm -3 ; A P-type AlGaN layer was grown on the electron blocking layer at a growth temperature of 800°C to 1200°C and a Mg doping concentration of 2×10 18 ~1×10 19 cm -3 .

8. The method for preparing a multi-wavelength ultraviolet LED according to claim 6, wherein: A P-type ohmic contact layer is grown on the P-type AlGaN layer. The P-type ohmic contact layer is a P-type GaN layer. The growth temperature is 800°C to 1100°C, and the Mg doping concentration is 1×10 19 ~3×10 19 cm -3 ; Annealing under an inert atmosphere can produce a multi-wavelength emitting ultraviolet LED.

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