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

Abstract

The invention relates to the technical field of ultraviolet LED manufacturing, in particular to a crystal face regulation and control type wide-spectrum deep ultraviolet LED chip and a preparation method thereof. Comprising the steps that a patterned substrate is of a three-dimensional structure with protrusions or recesses, and the height difference between the highest point or the lowest point of each protrusion or recess and the surface of the substrate ranges from 0 micrometer to 10 micrometers; the protrusions or the recesses are composed of inclined plane areas, and the included angle between the inclined plane areas and the surface of the substrate is 0-15 degrees. The epitaxial structure sequentially comprises an n-type AlGaN layer, an AlGaN multi-quantum well structure layer and a p-type AlGaN layer; the p-type ohmic contact composite metal layer is arranged 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 arranged. The method has the advantages that multiple components are formed in different areas by regulating and controlling the AlGaN component through the inclination angle, multispectral integration on a single chip is achieved, and stability is high; the wavelength range covered by the light-emitting wave band is larger than 20 nm.

Description

Technical Field

[0001] The present invention relates to the technical field of ultraviolet LED manufacturing, and in particular to a crystal plane-controlled wide-spectrum deep ultraviolet LED chip and a preparation method thereof. Background Art

[0002] Ultraviolet light is a high-energy electromagnetic wave with a wavelength of 200-400nm. When ultraviolet light is irradiated on microorganisms, the chemical bonds of the DNA molecules and protein molecules in the microorganisms can interact with the ultraviolet light and destroy their molecular structure, thereby disinfecting the microorganisms. Based on this principle, the use of ultraviolet light to disinfect microorganisms has the advantages of a wide killing range and no drug resistance. Compared with chemical disinfection, ultraviolet light disinfection also has the advantages of no chemical residues and toxic side effects. It has significant advantages in high-purity circular disinfection fields such as laboratories, pharmaceutical factories, and drinking water. However, the most widely used ultraviolet light source is still mercury lamps, which contain heavy metal mercury elements and have high energy consumption, large size and short life. Ultraviolet LEDs, especially UVC band LEDs, are strong competitors to replace mercury lamps. They have the advantages of a single luminous wavelength, no ozone generation, environmental friendliness, easy integration, long life, and stable equipment.

[0003] However, different microorganisms have varying inactivation sensitivities to different wavelengths of UV light. For example, viruses are most sensitive to the 255-270nm wavelength range, while bacterial spores are most sensitive to the 250nm wavelength range. Bacteria like E. coli are more sensitive to wavelengths around 280nm, and so on. However, due to the physical properties of light-emitting diodes, the full-width at half-maximum (FWHM) of the UV LED emission spectrum generally does not exceed 10nm. Therefore, LED-based disinfection and inactivation equipment designed for specific application scenarios can only effectively inactivate specific viruses or bacteria and cannot achieve broad-spectrum coverage.

[0004] Currently, there are two main approaches to broadening the UV LED spectrum: multi-chip integration and quantum structure manipulation. Integrating UV LED chips with different emission bands on a single substrate can effectively expand the emission band, but this takes up a lot of space. Multi-chip integration also requires a larger footprint and more complex drive circuits, which reduces reliability. Broadening the emission band of a single chip by manipulating the quantum structure of the active region, on the other hand, presents challenges such as complex epitaxial growth processes and reduced luminous efficiency. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a crystal plane-controlled wide-spectrum deep ultraviolet LED chip and a preparation method thereof.

[0006] The first object of the present invention is to provide a crystal plane-controlled wide-spectrum deep ultraviolet LED chip, comprising a tightly stacked patterned substrate and an epitaxial structure; The patterned substrate is a three-dimensional structure with protrusions or depressions, and the height difference between the highest point or the lowest point of the protrusion or depression and the substrate surface ranges from 0 to 10 microns; the protrusion or depression is composed of an inclined plane area, and the angle between the inclined plane area and the substrate surface is 0 to 15 degrees; the patterned substrate has at least two inclined plane areas; The epitaxial structure includes, 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%; A p-type ohmic contact composite metal layer is provided 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 provided on the surface of the exposed portion of the n-type AlGaN layer.

[0007] Preferably, the connecting area between the protrusions and the depressions in the patterned substrate is a continuous surface; the patterned substrate is composed of a 0.5 degree inclined area, a 0.7 degree inclined area, a 1 degree inclined area and a 1.4 degree inclined area from the center to the outside; wherein the inclination direction of the 0.5 degree inclined area and the 1 degree inclined area is descending from the center to the outer edge, and the inclination direction of the 0.7 degree inclined area and the 1.4 degree inclined area is ascending from the center to the outer edge.

[0008] Preferably, the AlGaN multi-quantum well structure layer has one or more quantum wells and quantum barriers, which are arranged alternately; the Al component of the quantum well is smaller 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.

[0009] Preferably, 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 aluminum component of the quantum well is 60% and the thickness is 3-5 nanometers; the aluminum component of the quantum barrier is 80% and the thickness is 10-12 nanometers.

[0010] 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 of the p-type AlGaN layer has 10 14 ~10 21 cm -3 The hole concentration.

[0011] Preferably, the thickness of the n-type AlGaN layer is 1000-1400 nanometers, the aluminum component is 60%, the n-type dopant is silicon, and the doping concentration is 10 18 cm -3The thickness of the p-type AlGaN layer is 80~120 nanometers, the aluminum component is 10%, the p-type dopant is magnesium, and the doping concentration is 10 18 cm -3 .

[0012] 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.

[0013] The second object of the present invention is to provide a method for preparing a crystal plane-controlled wide-spectrum deep ultraviolet LED chip, which specifically includes the following steps: S1. Preparing a patterned substrate with patterns at different tilt angles; specifically comprising: S11. Spin-coating a positive photoresist layer having a thickness of 0.5 to 15 μm on the sapphire substrate; S12. The positive photoresist layer is exposed and developed to obtain a patterned photoresist layer with different tilt angles; S13. performing dry etching to etch the pattern onto the substrate to obtain a patterned substrate having patterns with different tilt angles; S2. epitaxially growing an n-type AlGaN layer on a patterned substrate, and then sequentially growing an AlGaN multi-quantum well structure layer and a p-type AlGaN layer; S3. Etch from the p-type AlGaN layer down to the n-type AlGaN layer, exposing an area of ​​20-35% of the n-type AlGaN layer; S4. depositing a 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. depositing a metal on the surface of the p-type AlGaN layer to obtain a p-type ohmic contact composite metal layer; S6. Package the prepared LED chip to obtain a crystal-surface-regulated wide-spectrum deep ultraviolet LED chip.

[0014] Preferably, step S12 is exposed using laser direct writing lithography equipment; the epitaxial growth in step S2 is performed using MOCVD, MBE, or HVPE equipment; and step S3 is etched using photolithography and etching processes, with the area of ​​the n-type AlGaN layer exposed by etching being 30%.

[0015] Preferably, step S4 uses electron beam evaporation to sequentially deposit Ti / Al / Ti / Au metals to obtain an n-type ohmic contact composite metal layer; step S5 uses electron beam evaporation to sequentially deposit Ni / Au metals to obtain a p-type ohmic contact composite metal layer.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) The present invention epitaxially grows an AlGaN-based deep ultraviolet LED structure on a patterned substrate with different tilt angles, and utilizes the regulatory effect of the substrate tilt angle on the AlGaN component to form multiple components in different regions of a single chip, thereby achieving multi-spectral integration on a single chip; it has the advantages of high integration and high stability; (2) Controlling the AlGaN composition by the substrate tilt angle has a simpler process flow than controlling the AlGaN composition by designing the multilayer structure of the active area in the epitaxial process, and the emission center wavelength is more stable and controllable; (3) The prepared crystal-surface-controlled wide-spectrum deep ultraviolet LED chip (wide-band deep ultraviolet light-emitting diode) has a light-emitting band covering a wavelength range greater than 20 nm (e.g., 250 nm to 270 nm). Compared with the common deep ultraviolet LEDs on the market that can only cover a 10 nm band, the device of the present invention has a wider range of microbial disinfection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 3 is a schematic diagram of the cross-sectional structure of a crystal plane-regulated wide-spectrum deep ultraviolet LED chip provided according to an embodiment of the present invention.

[0018] Figure 2 3 is a schematic diagram of a patterned substrate structure provided according to an embodiment of the present invention.

[0019] Figure 3 The figure is a flow chart of preparing a patterned substrate according to an embodiment of the present invention.

[0020] Reference numerals: 1. Patterned substrate; 2. n-type AlGaN layer; 3. AlGaN multi-quantum well structure layer; 4. p-type AlGaN layer; 5. p-type ohmic contact composite metal layer; 6. n-type ohmic contact composite metal layer; 101. 0.5-degree tilt area; 102. 0.7-degree tilt area; 103. 1-degree tilt area; 104. 1.4-degree tilt area; 201. Sapphire substrate; 202. Positive photoresist layer; 203. Graphic photoresist layer. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, identical modules are denoted by identical reference numerals. In the case of identical reference numerals, their names and functions are also identical. Therefore, their detailed description will not be repeated.

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0023] The present invention provides a crystal plane-controlled wide-spectrum deep ultraviolet LED chip. By utilizing the substrate bevel angle to regulate the composition of AlGaN, the patterned area has different AlGaN compositions, thereby forming an active region composed of multiple AlGaN components within a single chip and broadening its luminous spectrum. Specifically, the chip comprises a tightly stacked patterned substrate and an epitaxial structure; 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 AlGaN content is 0-100%. The p-type AlGaN layer has a 10 14 ~10 21 cm -3 The hole concentration; A p-type ohmic contact composite metal layer is provided on the p-type AlGaN layer; The patterned substrate is a three-dimensional structure with protrusions or depressions, and the height difference between the highest point or lowest point of the protrusion or depression and the substrate surface ranges from 0 to 10 microns; the protrusion or depression is composed of an inclined plane area, and the angle between the inclined plane area and the substrate surface is 0 to 15 degrees. There are at least two inclined plane areas on the patterned substrate; the connecting area between the protrusion and the depression is a continuous surface, without any area with sudden height changes; Specifically, the patterned substrate is divided into a 0.5 degree tilted area, a 0.7 degree tilted area, a 1 degree tilted area, and a 1.4 degree tilted area from the center outward; wherein the tilt directions of the 0.5 degree tilted area and the 1 degree tilted area are descending from the center to the outer edge, and the tilt directions of the 0.7 degree tilted area and the 1.4 degree tilted area are ascending from the center to the outer edge; In a specific embodiment, the size of the 0.5 degree tilt region is 100×100 μm. 2 , the center point height is recorded as 0, the outer edge height is -436 nm; the outer edge length of the 0.7 degree tilt area is 200 μm, and the effective tilt size is 3×10 4 μm 2 The height of the outer edge of the 0.7 degree tilt region is 175 nanometers; the outer edge of the 1 degree tilt region is 300 μm long, and the effective tilt size is 5×10 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 7×10 4 μm 2, the outer edge height of the 1.4 degree tilt area is 524 nanometers.

[0024] One side of the n-type AlGaN layer is partially exposed, and the exposed area is 20~35% of the total surface area of ​​the n-type AlGaN layer; an n-type ohmic contact composite metal layer is provided on the surface of the exposed portion of the n-type AlGaN layer; the n-type AlGaN layer has 10 14 ~10 21 cm -3 The electron concentration of The AlGaN multi-quantum well structure layer has one or more quantum wells and quantum barriers, which are arranged alternately. The Al component of the quantum well is smaller than that of the quantum barrier. The thickness of the quantum well is 1-8nm, and the thickness of the quantum barrier is 3-20nm. Due to different substrate tilt angles in the same region, the AlGaN material composition is different at different tilt angles. Therefore, the AlGaN epitaxial structure grown in the same region has different compositions. In a specific embodiment, the thickness of the n-type AlGaN layer is 1200 nanometers, the aluminum content is 60%, the n-type dopant is silicon, and the doping concentration is 10 18 cm -3 The AlGaN multi-quantum well structure layer has a total thickness of 75 nanometers and has five periods of quantum wells and quantum barriers, which are 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. The thickness of the p-type AlGaN layer is 100 nanometers, the aluminum component is 10%, and the p-type dopant is magnesium with a doping concentration of 10 18 cm -3 ; In a specific embodiment, 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.

[0025] A method for preparing a crystal plane-controlled wide-spectrum deep ultraviolet LED chip comprises the following steps: S1. Preparing a patterned substrate with patterns at different tilt angles; specifically comprising: S11. Spin-coating a positive photoresist layer having a thickness of 0.5 to 15 μm on the sapphire substrate; S12. The positive photoresist layer is exposed and developed to obtain a patterned photoresist layer with different tilt angles; Specifically, a laser direct writing lithography device is used for exposure; S13. performing dry etching to etch the pattern onto the substrate to obtain a patterned substrate having patterns with different tilt angles; S2. epitaxially growing an n-type AlGaN layer on a patterned substrate, and then sequentially growing an AlGaN multi-quantum well structure layer and a p-type AlGaN layer; Epitaxial growth uses MOCVD, MBE, HVPE and other epitaxial growth equipment; S3. Etch down from the p-type AlGaN layer to the n-type AlGaN layer using a photolithography and etching process, exposing an area of ​​20-35% of the n-type AlGaN layer. S4. depositing a metal on the surface of the exposed portion of the n-type AlGaN layer to obtain an n-type ohmic contact composite metal layer; Specifically, Ti / Al / Ti / Au metals are deposited in sequence using an electron beam evaporation method; S5. depositing a metal on the surface of the p-type AlGaN layer to obtain a p-type ohmic contact composite metal layer; Specifically, Ni / Au metals are deposited in sequence using an electron beam evaporation method; S6. Package the prepared LED chip to obtain a crystal-surface-regulated wide-spectrum deep ultraviolet LED chip.

[0026] Example 1 This embodiment provides a crystal plane-controlled wide-spectrum deep ultraviolet LED chip, the device structure is as follows Figure 1-Figure 2 , comprising a patterned substrate 1 and an epitaxial structure stacked closely in sequence; the epitaxial structure comprises, from bottom to top, an n-type AlGaN layer 2, an AlGaN multi-quantum well structure layer 3, and a p-type AlGaN layer 4; One side of the n-type AlGaN layer 2 is partially exposed, and the exposed area is 30% of the surface area of ​​the entire n-type AlGaN layer 2; an n-type ohmic contact composite metal layer 6 is provided on the surface of the exposed portion of the n-type AlGaN layer 2; The p-type ohmic contact composite metal layer 5 is provided on the p-type AlGaN layer 4; Specifically, the patterned substrate 1 is a sapphire substrate with patterns of different tilt angles, which serves as the basis of the entire structure and is used to control the crystal plane; Figure 2 As shown, from the center outward, there are a 0.5 degree tilt area 101, a 0.7 degree tilt area 102, a 1 degree tilt area 103, and a 1.4 degree tilt area 104; The size of the 0.5 degree tilt region 101 is 100×100 μm 2 , the center point height is recorded as 0, the outer edge height is -436 nanometers, and the tilt direction of this area is decreasing from the center to the outer edge; at this time, according to trigonometric functions, it is not difficult to calculate that the tilt angle of this area is 0.5 degrees; The outer edge length of the 0.7 degree tilt region 102 is 200 μm, and the effective tilt size is 3×10 4 μm 2The inner edge of the 0.7-degree tilt region 102, i.e., the outer edge of the 0.5-degree tilt region 101, has a height of -436 nanometers, and the outer edge of the 0.7-degree tilt region 102 has a height of 175 nanometers. The tilt direction of the region rises from the center to the outer edge. At this time, it is not difficult to calculate the tilt angle of the region as 0.7 degrees based on trigonometric functions. The outer edge length of the 1 degree tilt region 103 is 300 μm, and the effective tilt size is 5×10 4 μm 2 ; The inner edge of the 1-degree tilted area 103, that is, the outer edge of the 0.7-degree tilted area 102, has a height of 175 nanometers, and the outer edge height of the 1-degree tilted area 103 is -698 nanometers. The tilt direction of the area is descending from the center to the outer edge; at this time, it is not difficult to calculate that the tilt angle of the area is 1 degree based on trigonometric functions.

[0027] The outer edge length of the 1.4 degree tilt region 104 is 400 μm, and the effective tilt size is 7×10 4 μm 2 ; The inner edge of the 1.4-degree inclined area 104, that is, the outer edge of the 1-degree inclined area 103, has a height of -698 nanometers, and the outer edge height of the 1.4-degree inclined area 104 is 524 nanometers. The inclination direction of the area is rising from the center to the outer edge; at this time, it is not difficult to calculate the inclination angle of the area as 1.4 degrees based on trigonometric functions.

[0028] The n-type AlGaN layer 2 is grown on the patterned substrate 1 and serves as an electron injection layer; The AlGaN multi-quantum well structure layer 3 is located on the n-type AlGaN layer 2 and includes multiple quantum wells for achieving light emission of a specific wavelength; The p-type AlGaN layer 4 is grown on the AlGaN multi-quantum well structure layer 3 and serves as a hole injection layer. Since the substrate has different tilt angles in the same region, the AlGaN material composition is different at different tilt angles. Therefore, the AlGaN epitaxial structure grown in the same region has different compositions. The p-type ohmic contact composite metal layer 5 is located on the p-type AlGaN layer 4 to achieve good hole extraction and current injection; The n-type ohmic contact composite metal layer 6 covers the surface of the exposed portion of the n-type AlGaN layer 2 to achieve 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 current loop.

[0029] Method for preparing patterned substrate 1 ( Figure 3) includes: first, spin-coating a 10-micron-thick positive photoresist layer 202 on a sapphire substrate 201; then using a laser direct write lithography device to expose and develop the positive photoresist layer 202 to obtain a patterned photoresist layer 203 with different tilt angles; dry-etching the sample to etch the pattern onto the sapphire substrate to obtain a patterned substrate 1 with patterns with different tilt angles.

[0030] In the process of preparing a crystal plane-controlled wide-spectrum deep ultraviolet LED chip, an n-type AlGaN layer 2 is first epitaxially grown on a patterned substrate 1 using an MOCVD device, and then an AlGaN multi-quantum well structure layer 3 and a p-type AlGaN layer 4 are sequentially grown; photolithography and etching processes are used to etch from the p-type AlGaN layer 4 downward to the n-type AlGaN layer 2, with the area of ​​the n-type AlGaN layer exposed by etching being 30%; Ti / Al / Ti / Au metals are sequentially deposited on the surface of the n-type AlGaN layer using an electron beam evaporation method to obtain an n-type ohmic contact composite metal layer 6; Ni / Au metals are sequentially deposited on the surface of the p-type AlGaN layer 4 using an electron beam evaporation method to obtain a p-type ohmic contact composite metal layer 5.

[0031] The method for preparing a crystal plane-controlled wide-spectrum deep ultraviolet LED chip specifically comprises the following steps: S1. Preparation of a patterned substrate 1 with patterns at different tilt angles: S11. A positive photoresist layer 202 having a thickness of 10 μm is spin-coated on the sapphire substrate 201; S12 using a laser direct write lithography device to expose and develop the positive photoresist layer 202 to obtain a patterned photoresist layer 203 with different tilt angles; S13. Perform dry etching to etch the pattern onto the substrate to obtain a patterned substrate 1 with patterns having different tilt angles.

[0032] S2. epitaxially growing an n-type AlGaN layer 2 on a patterned substrate 1, and then sequentially growing an AlGaN multi-quantum well structure layer 3 and a p-type AlGaN layer 4; The thickness of the n-type AlGaN layer 2 is 1200 nm, the aluminum component is 60%, the n-type dopant is silicon, and the doping concentration is 10 18 cm -3 ; The AlGaN multi-quantum well structure layer 3 has a total thickness of 75 nanometers and has five periods of quantum wells and quantum barriers, with the quantum wells and quantum barriers arranged alternately. The quantum wells have an aluminum composition of 60% and a thickness of 4 nanometers; the quantum barriers have an aluminum composition of 80% and a thickness of 11 nanometers. The thickness of the p-type AlGaN layer 4 is 100 nm, the aluminum component is 10%, and the p-type dopant is magnesium with a doping concentration of 10 18 cm-3 ; Since the substrate has different tilt angles in the same region, the AlGaN material composition is different at different tilt angles, and thus the AlGaN epitaxial structures grown in the same region have different compositions.

[0033] S3. Etch down from the p-type AlGaN layer 4 to the n-type AlGaN layer 2 by photolithography and etching, exposing 30% of the n-type AlGaN layer; S4. Ti / Al / Ti / Au metals are sequentially deposited on the surface of the exposed portion of the n-type AlGaN layer by electron beam evaporation to obtain an n-type ohmic contact composite metal layer 6; S5. Ni / Au metals are sequentially deposited 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; S6. Package the prepared LED chip to obtain a crystal-surface-regulated wide-spectrum deep ultraviolet LED chip.

[0034] In this embodiment, regions with varying tilt angles have varying AlGaN compositions. Specifically, regions with larger angles have a smaller Al composition, enabling multi-band emission from a single chip. Compared to a deep-ultraviolet (DUV) LED with the same structure grown on an unpatterned sapphire substrate, the surface-modulated, wide-spectrum DUV LED chip of this invention boasts a 100% increase in spectral range.

[0035] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0036] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A crystal plane-controlled wide-spectrum deep ultraviolet LED chip, characterized by: including tightly stacked patterned substrates and epitaxial structures; The patterned substrate is a three-dimensional structure with protrusions or depressions, and the height difference between the highest point or the lowest point of the protrusion or depression and the substrate surface ranges from 0 to 10 microns; the protrusion or depression is composed of an inclined plane area, and the angle between the inclined plane area and the substrate surface is 0 to 15 degrees; the patterned substrate has at least two inclined plane areas; The epitaxial structure includes, 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%; A p-type ohmic contact composite metal layer is provided 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 provided on the surface of the exposed portion of the n-type AlGaN layer.

2. The crystal plane-controlled wide-spectrum deep ultraviolet LED chip according to claim 1, characterized in that: The connecting area between the protrusions and the depressions in the patterned substrate is a continuous surface; the patterned substrate is divided into a 0.5 degree inclined area, a 0.7 degree inclined area, a 1 degree inclined area and a 1.4 degree inclined area from the center outward; The inclination direction of the 0.5 degree area and the 1 degree area is descending from the center to the outer edge, and the inclination direction of the 0.7 degree area and the 1.4 degree area is ascending from the center to the outer edge.

3. The crystal plane-controlled wide-spectrum 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 component of the quantum well is smaller 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.

4. The crystal plane-controlled wide-spectrum deep ultraviolet LED chip according to claim 3, 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 component of 60% and a thickness of 3-5 nanometers; the quantum barriers have an aluminum component of 80% and a thickness of 10-12 nanometers.

5. The crystal plane-controlled wide-spectrum 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 of the p-type AlGaN layer has 10 14 ~10 21 cm -3 The hole concentration.

6. The crystal plane-controlled wide-spectrum deep ultraviolet LED chip according to claim 1, characterized in that: The thickness of the n-type AlGaN layer is 1000-1400 nanometers, the aluminum component 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 nanometers, the aluminum component is 10%, the p-type dopant is magnesium, and the doping concentration is 10 18 cm -3 .

7. The crystal plane-controlled wide-spectrum 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.

8. The method for preparing a crystal plane-controlled wide-spectrum deep ultraviolet LED chip according to claim 1, characterized in that: The specific steps include: S1. Preparing a patterned substrate with patterns at different tilt angles; specifically comprising: S11. Spin-coating a positive photoresist layer having a thickness of 0.5 to 15 μm on the sapphire substrate; S12. The positive photoresist layer is exposed and developed to obtain a patterned photoresist layer with different tilt angles; S13. performing dry etching to etch the pattern onto the substrate to obtain a patterned substrate having patterns with different tilt angles; S2. epitaxially growing an n-type AlGaN layer on a patterned substrate, and then sequentially growing an AlGaN multi-quantum well structure layer and a p-type AlGaN layer; S3. Etch from the p-type AlGaN layer down to the n-type AlGaN layer, exposing an area of ​​20-35% of the n-type AlGaN layer; S4. depositing a 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. depositing a metal on the surface of the p-type AlGaN layer to obtain a p-type ohmic contact composite metal layer; S6. Package the prepared LED chip to obtain a crystal-surface-regulated wide-spectrum deep ultraviolet LED chip.

9. The method for preparing a crystal plane-controlled wide-spectrum deep ultraviolet LED chip according to claim 8, characterized in that: The step S12 is exposed using a laser direct writing lithography device; the epitaxial growth in the step S2 is performed using MOCVD, MBE, and HVPE equipment; and the step S3 is etched using a photolithography and etching process, with the area of ​​the n-type AlGaN layer exposed by etching being 30%.

10. The method for preparing a crystal plane-controlled wide-spectrum deep ultraviolet LED chip according to claim 8, characterized in that: In step S4, Ti / Al / Ti / Au metals are sequentially deposited by electron beam evaporation to obtain an n-type ohmic contact composite metal layer; in step S5, Ni / Au metals are sequentially deposited by electron beam evaporation to obtain a p-type ohmic contact composite metal layer.

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