Crystal face regulation type wide spectrum deep ultraviolet LED chip and preparation method thereof

Abstract

The present application relates to the technical field of ultraviolet LED manufacturing, and particularly relates to a crystal face regulation type wide-spectrum deep ultraviolet LED chip and a preparation method thereof. The method comprises the following steps: a patterned substrate is a three-dimensional structure with protrusions or recesses, the highest point or the lowest point of the protrusions or recesses has a height difference of 0-10 microns with the substrate surface; the protrusions or recesses are composed of inclined plane regions, the angle between the inclined plane regions and the substrate surface is 0-15 degrees; an epitaxial structure comprises an n-type AlGaN layer, an AlGaN multi-quantum well structure layer and a p-type AlGaN layer in sequence; a p-type ohmic contact composite metal layer is arranged on the p-type AlGaN layer; and a part of the n-type AlGaN layer is exposed, and an n-type ohmic contact composite metal layer is arranged. The method has the advantages that the inclination angle is used to regulate the AlGaN component, multiple components are formed on different regions, monolithic multispectral integration is achieved, and the stability is high; and the light-emitting wavelength band covers a wavelength range of greater than 20 nm.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultraviolet LED manufacturing, in particular to a crystal face regulated wide spectrum deep ultraviolet LED chip and a preparation method thereof. BACKGROUND

[0002] Ultraviolet light is a high-energy electromagnetic wave with a wavelength of 200-400 nm. When ultraviolet light irradiates microorganisms, the chemical bonds of DNA molecules and protein molecules in the microorganisms can interact with ultraviolet light and destroy their molecular structure, thereby killing the microorganisms. Based on this principle, using ultraviolet light to kill microorganisms has the advantages of wide killing range and no drug resistance. Compared with chemical killing, ultraviolet light killing also has the advantages of no chemical residues and toxic side effects, and has significant advantages in the fields of high-purity ring killing such as laboratories, pharmaceutical factories and drinking water. However, the widely used ultraviolet light source is a mercury lamp, which contains heavy metal mercury elements and has high energy consumption, large volume and short service life. Ultraviolet LED, especially UVC band LED, is a strong competitor to replace mercury lamps, with the advantages of single emission wavelength, no ozone generation, environmental friendliness, easy integration, long service life and stable equipment.

[0003] However, different types of microorganisms have different inactivation sensitivities to different wavelengths of ultraviolet light. For example, viruses are most sensitive to the 255-270 nm band, while bacteria spores are most sensitive to the 250 nm band, and bacteria such as E. coli are more sensitive to wavelengths around 280 nm. However, based on the physical properties of light-emitting diodes, the full width at half maximum of the emission spectrum of ultraviolet LED is generally not more than 10 nm. Therefore, LED-related killing and inactivation equipment designed for specific application scenarios can only achieve high inactivation efficiency for specific types of viruses or bacteria, and cannot achieve broad spectrum coverage.

[0004] The current methods for widening the emission spectrum of ultraviolet LED mainly include two methods: multi-chip integration and quantum structure regulation. Integrating ultraviolet LED chips of different emission wavelengths on the same substrate can effectively expand the emission wavelength, but this will occupy a large space, and multi-chip integration requires a larger volume and more complex driving circuit, which will reduce its reliability. The method of widening the emission spectrum of a single chip by regulating the quantum structure of the active region has problems such as complex epitaxial process and reduced light emission efficiency. SUMMARY

[0005] The present application provides a crystal face regulated wide spectrum deep ultraviolet LED chip and a preparation method thereof to solve the above problems.

[0006] The first object of the present application is to provide a crystal face regulated wide spectrum deep ultraviolet LED chip, which comprises a tightly stacked patterned substrate and an epitaxial structure.

[0007] The patterned substrate is a three-dimensional structure with protrusions or depressions, and the height difference between the highest or lowest point of the protrusion or depression and the substrate surface ranges from 0 to 10 micrometers; the protrusion or depression is composed of inclined plane regions, and the angle between the inclined plane regions and the substrate surface is 0 to 15 degrees; there are at least two inclined plane regions on the patterned substrate.

[0008] The epitaxial structure, from bottom to top, comprises an n-type AlGaN layer, an AlGaN multi-quantum-well structure layer, and a p-type AlGaN layer; the Al content in the AlGaN is 0-100%.

[0009] The p-type ohmic contact composite metal layer is disposed on the p-type AlGaN layer;

[0010] One side of the n-type AlGaN layer is partially exposed, and an n-type ohmic contact composite metal layer is disposed on the surface of the exposed part of the n-type AlGaN layer.

[0011] Preferably, the connection area between the protrusions and depressions in the patterned substrate is a continuous surface; the patterned substrate consists of regions tilted at 0.5 degrees, 0.7 degrees, 1 degree, and 1.4 degrees from the center outwards; wherein the tilt direction of the 0.5-degree and 1-degree tilted regions is downward from the center to the outer edge, and the tilt direction of the 0.7-degree and 1.4-degree tilted regions is upward from the center to the outer edge.

[0012] Preferably, the AlGaN multi-quantum-well structure layer has one or more quantum wells and quantum barriers, with the quantum wells and quantum barriers arranged alternately; the Al composition of the quantum wells is less than the Al composition of the quantum barriers, the thickness of the quantum wells is 1~8 nm, and the thickness of the quantum barriers is 3~20 nm.

[0013] Preferably, the total thickness of the AlGaN multi-quantum-well structure layer is 70-80 nanometers, and it has five periods of quantum wells and quantum barriers; the aluminum composition of the quantum wells is 60%, and the thickness is 3-5 nanometers; the aluminum composition of the quantum barriers is 80%, and the thickness is 10-12 nanometers.

[0014] Preferably, the exposed area of ​​the n-type AlGaN layer is 20-35% of the total surface area; the n-type AlGaN layer has 10 14 ~10 21 cm -3 The electron concentration; the p-type AlGaN layer has 10 14 ~10 21 cm -3 Hole concentration.

[0015] Preferably, the thickness of the n-type AlGaN layer is 1000~1400 nm, the aluminum composition is 60%, the n-type dopant is silicon, and the doping concentration is 10. 18 cm-3 The thickness of the p-type AlGaN layer is 80-120 nm, the aluminum component is 10%, the p-type dopant is magnesium, and the doping concentration is 10 18 cm -3 .

[0016] Preferably, the composite metal of the n-type ohmic contact composite metal layer is Ti / Al / Ti / Au, and the composite metal of the p-type ohmic contact composite metal layer is Ni / Au.

[0017] The second object of the application is to provide a preparation method of the crystal face regulated wide spectrum deep ultraviolet LED chip.

[0018] S1. Preparing a patterned substrate with different inclination angle patterns; specifically comprising:

[0019] S11. Spinning 0.5-15 microns of positive photoresist layer on the sapphire substrate;

[0020] S12. Exposing and developing the positive photoresist layer to obtain a patterned photoresist layer with different inclination angles;

[0021] S13. Dry etching to etch the pattern onto the substrate to obtain a patterned substrate with different inclination angle patterns;

[0022] S2. Epitaxially growing an n-type AlGaN layer on the patterned substrate, and then growing an AlGaN multi-quantum well structure layer and a p-type AlGaN layer in sequence;

[0023] S3. Etching from the p-type AlGaN layer to the n-type AlGaN layer, and the etching exposes an area of 20-35% of the n-type AlGaN layer;

[0024] S4. Depositing metal on the surface of the exposed part of the n-type AlGaN layer to obtain an n-type ohmic contact composite metal layer;

[0025] S5. Depositing metal on the surface of the p-type AlGaN layer to obtain a p-type ohmic contact composite metal layer;

[0026] S6. Packaging the prepared LED chip to obtain a crystal face regulated wide spectrum deep ultraviolet LED chip.

[0027] Preferably, step S12 uses a laser direct writing lithography device for exposure; the epitaxial growth of step S2 is performed using MOCVD, MBE, or HVPE device; step S3 is etched by lithography and etching process, and the area of the n-type AlGaN layer exposed by etching is 30%.

[0028] Preferably, step S4 uses the method of electron beam evaporation to sequentially deposit Ti / Al / Ti / Au metal to obtain an n-type ohmic contact composite metal layer; and step S5 uses the method of electron beam evaporation to sequentially deposit Ni / Au metal to obtain a p-type ohmic contact composite metal layer.

[0029] Compared with the prior art, the present application can achieve the following beneficial effects:

[0030] (1) The present application realizes the monolithic multi-spectrum integration by epitaxially growing the AlGaN-based deep ultraviolet LED structure on the patterned substrate with different inclination angles, and forming multiple components on different regions of a single chip by using the substrate inclination angle to control the AlGaN component, thereby having the advantages of high integration and high stability.

[0031] (2) The substrate inclination angle control of the AlGaN component ratio has a simpler process flow than the epitaxial process active region multilayer structure design control of the AlGaN component, and the light emission center wavelength is more stable and controllable.

[0032] (3) The prepared crystal face regulation type wide spectrum deep ultraviolet LED chip (wide band deep ultraviolet light emitting diode) has a light emission band covering a wavelength range of more than 20 nm (such as 250 nm to 270 nm), and compared with the common deep ultraviolet LED on the market which can only cover a 10 nm band, the device has a wider range of microbial disinfection. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a crystal face regulation type wide spectrum deep ultraviolet LED chip cross section structure schematic diagram provided according to an embodiment of the present application.

[0034] Figure 2 is a patterned substrate structure schematic diagram provided according to an embodiment of the present application.

[0035] Figure 3 is a patterned substrate preparation flowchart provided according to an embodiment of the present application.

[0036] REFERENCE NUMERALS:

[0037] 1. Patterned substrate;

[0038] 2. n-type AlGaN layer;

[0039] 3. AlGaN multi-quantum well structure layer;

[0040] 4. p-type AlGaN layer;

[0041] 5. p-type ohmic contact composite metal layer;

[0042] 6. n-type ohmic contact composite metal layer;

[0043] 101. a 0.5 degree tilt region; 102. a 0.7 degree tilt region; 103. a 1 degree tilt region; 104. a 1.4 degree tilt region; 201. a sapphire substrate; 202. a positive photoresist layer; 203. a patterned photoresist layer. DETAILED DESCRIPTION

[0044] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0045] In order to make the objects, technical solutions, and advantages of the present application clearer, further detailed descriptions will be made to the present application in combination with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but do not constitute a limitation on the present application.

[0046] The present application provides a crystal face regulation type wide spectrum deep ultraviolet LED chip, which utilizes the component regulation effect of substrate tilt angle on AlGaN, so that the patterned region has different AlGaN components, thereby forming an active region composed of multiple AlGaN components in a single chip and widening the light emission spectrum range. Specifically, it comprises a patterned substrate and an epitaxial structure which are closely stacked in sequence; the epitaxial structure comprises, from bottom to top, an n-type AlGaN layer, an AlGaN multi-quantum well structure layer, and a p-type AlGaN layer; the Al component content in the AlGaN is 0-100%;

[0047] The p-type AlGaN layer has a hole concentration of 10 14 ~10 21 cm -3 ;

[0048] A p-type ohmic contact composite metal layer is arranged on the p-type AlGaN layer;

[0049] The patterned substrate has a three-dimensional structure with protrusions or depressions, and the height difference between the highest point or the lowest point of the protrusions or depressions and the substrate surface ranges from 0 to 10 microns; the protrusions or depressions are composed of tilt plane regions, the included angle between the tilt plane regions and the substrate surface is 0-15 degrees, and there are at least two tilt plane regions on the patterned substrate; the connection region of the protrusions and the depressions is a continuous surface, and there is no region with sudden height change;

[0050] Specifically, the patterned substrate comprises, from the center to the outside, a 0.5 degree tilt region, a 0.7 degree tilt region, a 1 degree tilt region, and a 1.4 degree tilt region; wherein the tilt directions of the 0.5 degree tilt region and the 1 degree tilt region are downward from the center to the outer edge, and the tilt directions of the 0.7 degree tilt region and the 1.4 degree tilt region are upward from the center to the outer edge.

[0051] In specific embodiments, the size of the 0.5 degree tilt region is 100 x 100 μm 2 , the center point height is recorded as 0, and the outer edge height is -436 nm; the outer edge length of the 0.7 degree tilt region is 200 μm, and the effective tilt size is 3 x 10 4 μm 2 ; the outer edge height of the 0.7 degree tilt region is 175 nm; the outer edge length of the 1 degree tilt region is 300 μm, and the effective tilt size is 5 x 10 4 μm 2 ; the outer edge height of the 1 degree tilt region is -698 nm; the outer edge length of the 1.4 degree tilt region is 400 μm, and the effective tilt size is 7 x 10 4 μm 2 ; and the outer edge height of the 1.4 degree tilt region is 524 nm.

[0052] The n-type AlGaN layer is partially exposed on one side, and the exposed area is 20-35% of the total surface area of the n-type AlGaN layer; the surface of the exposed portion of the n-type AlGaN layer is provided with an n-type ohmic contact composite metal layer; the n-type AlGaN layer has an electron concentration of 10 14 ~10 21 cm -3 ;

[0053] The AlGaN multi-quantum well structure layer has one or more quantum wells and quantum barriers arranged alternately; the Al component of the quantum well is less than that of the quantum barrier, the thickness of the quantum well is 1-8 nm, and the thickness of the quantum barrier is 3-20 nm; because the same region has different substrate tilt angles, the AlGaN material component is different at different tilt angles, and thus the AlGaN epitaxial structure grown in the same region has different components;

[0054] In specific embodiments, the thickness of the n-type AlGaN layer is 1200 nm, the aluminum component is 60%, the n-type dopant is silicon, and the doping concentration is 10 18 cm -3 ; the total thickness of the AlGaN multi-quantum well structure layer is 75 nm, and the quantum well and the quantum barrier have five periods arranged alternately; the aluminum component of the quantum well is 60%, and the thickness is 4 nm; the aluminum component of the quantum barrier is 80%, and the thickness is 11 nm; the thickness of the p-type AlGaN layer is 100 nm, the aluminum component is 10%, the p-type dopant is magnesium, and the doping concentration is 10 18 cm -3 ;

[0055] In specific embodiments, the composite metal of the n-type ohmic contact composite metal layer is Ti / Al / Ti / Au; and the composite metal of the p-type ohmic contact composite metal layer is Ni / Au.

[0056] A preparation method of a crystal face regulated wide spectrum deep ultraviolet LED chip, specifically comprising the following steps:

[0057] S1. Preparing a patterned substrate with different inclined angle patterns; specifically comprising:

[0058] S11. Spinning 0.5-15 microns of positive photoresist layer on the sapphire substrate;

[0059] S12. Exposing and developing the positive photoresist layer to obtain a patterned photoresist layer with different inclined angles;

[0060] Specifically, using a laser direct writing lithography equipment for exposure;

[0061] S13. Dry etching to etch the pattern onto the substrate to obtain a patterned substrate with different inclined angle patterns;

[0062] S2. Epitaxially growing an n-type AlGaN layer on the patterned substrate, and then growing an AlGaN multi-quantum well structure layer and a p-type AlGaN layer in sequence;

[0063] The epitaxial growth uses MOCVD, MBE, HVPE, etc. epitaxial growth equipment;

[0064] S3. Etching from the p-type AlGaN layer to the n-type AlGaN layer by lithography and etching process, and the etching exposes an area of 20-35% of the n-type AlGaN layer;

[0065] S4. Depositing metal on the surface of the exposed part of the n-type AlGaN layer to obtain an n-type ohmic contact composite metal layer;

[0066] Specifically, using the method of electron beam evaporation to deposit Ti / Al / Ti / Au metal in sequence;

[0067] S5. Depositing metal on the surface of the p-type AlGaN layer to obtain a p-type ohmic contact composite metal layer;

[0068] Specifically, using the method of electron beam evaporation to deposit Ni / Au metal in sequence;

[0069] S6. Packaging the prepared LED chip to obtain a crystal face regulated wide spectrum deep ultraviolet LED chip.

[0070] Embodiment 1

[0071] This embodiment provides a crystal face regulated wide spectrum deep ultraviolet LED chip, and the device structure is as followsFigures 1-2 It includes a patterned substrate 1 and an epitaxial structure that are stacked tightly in sequence; the epitaxial structure includes an n-type AlGaN layer 2, an AlGaN multi-quantum-well structure layer 3, and a p-type AlGaN layer 4 from bottom to top;

[0072] Among them, one side of the n-type AlGaN layer 2 is partially exposed, and the exposed area is 30% of the total surface area of ​​the n-type AlGaN layer 2; an n-type ohmic contact composite metal layer 6 is disposed on the surface of the exposed part of the n-type AlGaN layer 2.

[0073] p-type ohmic contact composite metal layer 5 is disposed on p-type AlGaN layer 4;

[0074] Specifically, the patterned substrate 1 is a sapphire substrate with patterns having different tilt angles, serving as the basis of the entire structure and used to control the crystal planes; such as Figure 2 As shown, from the center outwards, there are regions 101 with an inclination of 0.5 degrees, 102 with an inclination of 0.7 degrees, 103 with an inclination of 1 degree, and 104 with an inclination of 1.4 degrees.

[0075] The size of region 101, tilted at 0.5 degrees, is 100 × 100 μm. 2 The height of the center point is recorded as 0, and the height of the outer edge is -436 nanometers. The tilt direction of this region is downward from the center to the outer edge. At this time, it is not difficult to calculate the tilt angle of this region as 0.5 degrees using trigonometric functions.

[0076] The outer edge of the 0.7-degree tilt region 102 has a length of 200 μm, and the effective tilt size is 3 × 10. 4 μm 2 The height of the inner edge of the 0.7-degree tilted region 102, which is the outer edge of the 0.5-degree tilted region 101, is -436 nanometers, and the height of the outer edge of the 0.7-degree tilted region 102 is 175 nanometers. The tilt direction of this region is from the center to the outer edge. At this time, it is not difficult to calculate the tilt angle of this region as 0.7 degrees using trigonometric functions.

[0077] The outer edge of the 1-degree tilt region 103 has a length of 300 μm, and the effective tilt size is 5 × 10. 4 μm 2 The height of the inner edge of the tilted region 103 (i.e., the outer edge of the tilted region 102) is 175 nanometers, and the height of the outer edge of the tilted region 103 is -698 nanometers. The tilt direction of this region is downward from the center to the outer edge. At this time, it is not difficult to calculate the tilt angle of this region as 1 degree using trigonometric functions.

[0078] The outer edge of the 1.4-degree tilt region 104 has a length of 400 μm, and the effective tilt size is 7 × 10. 4 μm 2The inner edge of the 1.4-degree inclined region 104, i.e. the outer edge of the 1-degree inclined region 103, has a height of -698 nm, and the outer edge of the 1.4-degree inclined region 104 has a height of 524 nm, and the inclined direction of this region is from the center to the outer edge.

[0079] The n-type AlGaN layer 2 is grown on the patterned substrate 1 as an electron injection layer;

[0080] The AlGaN multi-quantum well structure layer 3 is located on the n-type AlGaN layer 2 and contains multiple quantum wells for realizing light emission of a specific wavelength;

[0081] The p-type AlGaN layer 4 is grown on the AlGaN multi-quantum well structure layer 3 as a hole injection layer; due to different substrate inclination angles in the same region, the AlGaN material composition is different at different inclination angles, and thus the AlGaN epitaxial structure grown in the same region has different compositions;

[0082] The p-type ohmic contact composite metal layer 5 is located on the p-type AlGaN layer 4 for realizing good hole extraction and current injection;

[0083] The n-type ohmic contact composite metal layer 6 covers the surface of the exposed part of the n-type AlGaN layer 2 for realizing good electron extraction and current injection; the n-type ohmic contact composite metal layer 6 and the p-type ohmic contact composite metal layer 5 together form a closed loop of current.

[0084] The preparation method of the patterned substrate 1 includes the following steps: Figure 3 First, a 10-micron-thick positive photoresist layer 202 is spin-coated on a sapphire substrate 201; then the positive photoresist layer 202 is exposed and developed using a laser direct writing lithography device to obtain a patterned photoresist layer 203 with different inclination angles; and the sample is subjected to dry etching to etch the pattern onto the sapphire substrate to obtain the patterned substrate 1 with different inclination angles.

[0085] In the process of preparing the crystal face regulation type wide-spectrum deep ultraviolet LED chip, the n-type AlGaN layer 2 is first epitaxially grown on the patterned substrate 1 using a MOCVD device, and then the AlGaN multi-quantum well structure layer 3 and the p-type AlGaN layer 4 are sequentially grown; the p-type AlGaN layer 4 is etched down to the n-type AlGaN layer 2 through a lithography and etching process, and the area of the n-type AlGaN layer exposed by etching is 30%; the Ti / Al / Ti / Au metal is sequentially deposited on the surface of the n-type AlGaN layer by electron beam evaporation to obtain the n-type ohmic contact composite metal layer 6; and the Ni / Au metal is sequentially deposited on the surface of the p-type AlGaN layer 4 by electron beam evaporation to obtain the p-type ohmic contact composite metal layer 5.

[0086] The preparation method of the crystal face regulation type wide spectrum deep ultraviolet LED chip specifically comprises the following steps:

[0087] S1. Preparing a patterned substrate 1 with different inclination angle patterns:

[0088] S11. Spinning 10 microns of positive photoresist layer 202 on sapphire substrate 201;

[0089] S12. Exposing and developing the positive photoresist layer 202 using a laser direct writing lithography device to obtain a patterned photoresist layer 203 with different inclination angles;

[0090] S13. Dry etching to etch the pattern onto the substrate to obtain a patterned substrate 1 with different inclination angle patterns.

[0091] S2. Epitaxially growing an n-type AlGaN layer 2 on the patterned substrate 1, and then growing an AlGaN multi-quantum well structure layer 3 and a p-type AlGaN layer 4 in sequence;

[0092] The thickness of the n-type AlGaN layer 2 is 1200 nanometers, the aluminum component is 60%, the n-type dopant is silicon, and the doping concentration is 10 18 cm -3 ;

[0093] The total thickness of the AlGaN multi-quantum well structure layer 3 is 75 nanometers, and it has five periods of quantum wells and quantum barriers arranged alternately; the aluminum component of the quantum well is 60%, and the thickness is 4 nanometers; the aluminum component of the quantum barrier is 80%, and the thickness is 11 nanometers;

[0094] The thickness of the p-type AlGaN layer 4 is 100 nanometers, the aluminum component is 10%, the p-type dopant is magnesium, and the doping concentration is 10 18 cm -3 ;

[0095] Due to the different substrate inclination angles in the same region, the AlGaN material components are different at different inclination angles, so the AlGaN epitaxial structure grown in the same region has different components.

[0096] S3. Etching from the p-type AlGaN layer 4 to the n-type AlGaN layer 2 by photolithography and etching process, and the etching exposes an area of 30% of the n-type AlGaN layer;

[0097] S4. Depositing Ti / Al / Ti / Au metal in sequence on the surface of the exposed part of the n-type AlGaN layer by electron beam evaporation method to obtain an n-type ohmic contact composite metal layer 6;

[0098] S5. Depositing Ni / Au metal in sequence on the surface of the p-type AlGaN layer 4 by electron beam evaporation to obtain a p-type ohmic contact composite metal layer 5;

[0099] S6. Packaging the prepared LED chip to obtain the crystal face regulation type wide spectrum deep ultraviolet LED chip.

[0100] In the embodiment, the different tilt angle regions have different AlGaN components, specifically, the regions with larger angles have smaller Al components, thereby realizing single-chip multi-band light emission. Compared with a deep ultraviolet light emitting diode with the same structure as the epitaxy on a non-patterned sapphire substrate, the crystal face regulation type wide spectrum deep ultraviolet LED chip has a 100% increase in the light emission spectrum range.

[0101] It should be understood that the various forms of flow shown above can be used to reorder, add or delete steps. For example, each step described in the present disclosure can be executed in parallel, sequentially or in a different order, as long as the desired results of the technical solutions of the present disclosure can be achieved, which is not limited herein.

[0102] The above specific embodiments do not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent replacement and improvement within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A crystal plane-tunable broadband deep ultraviolet LED chip, characterized in that: This includes closely stacked patterned substrates and epitaxial structures; The patterned substrate has a three-dimensional structure with protrusions or depressions, and the height difference between the highest or lowest point of the protrusion or depression and the substrate surface ranges from 0 to 10 micrometers; the protrusion or depression is composed of inclined plane regions, and the angle between the inclined plane regions and the substrate surface is 0 to 15 degrees; the patterned substrate has at least two inclined plane regions; the connecting area between the protrusions and depressions in the patterned substrate is a continuous surface; the patterned substrate has, from the center outwards, regions inclined at 0.5 degrees, 0.7 degrees, 1 degree, and 1.4 degrees respectively. The tilt direction of the 0.5-degree and 1-degree tilted areas is downward from the center to the outer edge, while the tilt direction of the 0.7-degree and 1.4-degree tilted areas is upward from the center to the outer edge. The epitaxial structure, from bottom to top, comprises an n-type AlGaN layer, an AlGaN multi-quantum-well structure layer, and a p-type AlGaN layer; the Al content in the AlGaN is 0-100%. The p-type ohmic contact composite metal layer is disposed on the p-type AlGaN layer; One side of the n-type AlGaN layer is partially exposed, and an n-type ohmic contact composite metal layer is disposed on the surface of the exposed part of the n-type AlGaN layer.

2. The crystal plane-tunable broadband deep ultraviolet LED chip according to claim 1, characterized in that: The AlGaN multi-quantum-well structure layer has one or more quantum wells and quantum barriers, which are arranged alternately; the Al composition of the quantum wells is smaller than that of the quantum barriers, the thickness of the quantum wells is 1~8nm, and the thickness of the quantum barriers is 3~20nm.

3. The crystal plane-tunable broadband deep ultraviolet LED chip according to claim 2, characterized in that: The AlGaN multi-quantum-well structure layer has a total thickness of 70-80 nanometers and has five periods of quantum wells and quantum barriers; the quantum wells have an aluminum composition of 60% and a thickness of 3-5 nanometers; the quantum barriers have an aluminum composition of 80% and a thickness of 10-12 nanometers.

4. The crystal plane-tunable broadband deep ultraviolet LED chip according to claim 1, characterized in that: The exposed area of ​​the n-type AlGaN layer is 20-35% of the total surface area; the n-type AlGaN layer has 10 14 ~10 21 cm -3 The electron concentration; the p-type AlGaN layer has 10 14 ~10 21 cm -3 Hole concentration.

5. A crystal plane-tunable broadband deep ultraviolet LED chip according to claim 1, characterized in that: The thickness of the n-type AlGaN layer is 1000~1400 nm, the aluminum composition is 60%, and the n-type dopant is silicon with a doping concentration of 10. 18 cm -3 The p-type AlGaN layer has a thickness of 80-120 nanometers, an aluminum composition of 10%, and magnesium as the p-type dopant with a doping concentration of 10. 18 cm -3 .

6. A crystal plane-tunable broadband deep ultraviolet LED chip according to claim 1, characterized in that: The composite metal of the n-type ohmic contact composite metal layer is Ti / Al / Ti / Au; the composite metal of the p-type ohmic contact composite metal layer is Ni / Au.

7. The method for fabricating a crystal plane-tunable broadband deep ultraviolet LED chip according to claim 1, characterized in that: Specifically, the steps include the following: S1. Fabricating a patterned substrate with patterns at different tilt angles; specifically including: S11. Spin-coat a positive photoresist layer with a thickness of 0.5~15 micrometers on a sapphire substrate; S12. Expose and develop the positive photoresist layer to obtain patterned photoresist layers with different tilt angles; S13. Perform dry etching to etch the pattern onto the substrate to obtain a patterned substrate with patterns at different tilt angles; S2. An n-type AlGaN layer is epitaxially grown on a patterned substrate, followed by the sequential growth of an AlGaN multi-quantum-well structure layer and a p-type AlGaN layer. S3. Etch down from the p-type AlGaN layer to the n-type AlGaN layer, exposing 20-35% of the n-type AlGaN layer. S4. Deposit metal on the surface of the exposed portion of the n-type AlGaN layer to obtain an n-type ohmic contact composite metal layer; S5. Deposit metal on the surface of the p-type AlGaN layer to obtain a p-type ohmic contact composite metal layer; S6. The prepared LED chip is packaged to obtain a crystal plane-tunable broadband deep ultraviolet LED chip.

8. The method for fabricating a crystal plane-tunable broadband deep ultraviolet LED chip according to claim 7, characterized in that: Step S12 uses a laser direct-write lithography equipment for exposure; the epitaxial growth in step S2 is performed using MOCVD, MBE, and HVPE equipment; step S3 uses lithography and etching processes to etch, exposing 30% of the n-type AlGaN layer.

9. The method for fabricating a crystal plane-tunable broadband deep ultraviolet LED chip according to claim 7, characterized in that: In step S4, Ti / Al / Ti / Au metals are deposited sequentially using electron beam evaporation to obtain an n-type ohmic contact composite metal layer; in step S5, Ni / Au metals are deposited sequentially using electron beam evaporation to obtain a p-type ohmic contact composite metal layer.

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