Ultraviolet LED chip and preparation method thereof

Abstract

The invention provides an ultraviolet LED chip which comprises a substrate, a transition layer, an n-type aluminum gallium nitride layer, a p-type aluminum gallium nitride layer, an aluminum gallium nitride quantum well light-emitting layer and an electrode layer. Wherein the transition layer is formed on the substrate; the n-type aluminum gallium nitride layer is formed in the first region on the transition layer and is suitable for responding to impressed current to generate electrons; the p-type aluminum gallium nitride layer is formed in a second region, spaced from the first region, on the transition layer and is suitable for responding to impressed current to generate holes; the aluminum gallium nitride quantum well light-emitting layer is formed on the transition layer, is located between the n-type aluminum gallium nitride layer and the p-type aluminum gallium nitride layer, comprises x barrier layers and x-1 potential well layers which are alternately arranged in the first direction, and is suitable for receiving electrons and holes which are transversely transmitted in the first direction and enabling the electrons and the holes to be compounded to generate ultraviolet light, the first direction is parallel to the substrate, and x is greater than or equal to 2 and less than or equal to 5; and the electrode layer is formed on the n-type aluminum gallium nitride layer and the p-type aluminum gallium nitride layer.

Description

Technical Field

[0001] The present disclosure relates to the technical field of ultraviolet LED chips, and in particular to an ultraviolet LED chip and a preparation method thereof. Background Art

[0002] Ultraviolet LED chips refer to LED devices with a central wavelength of light below 400nm, which can be widely used in various fields of physics, chemistry and biology such as gas detection, organic curing, sterilization and disinfection. At present, the demand for ultraviolet LED devices, especially deep ultraviolet LED devices, is increasing, and the quality requirements are getting higher and higher. The quality and performance of ultraviolet LED chips determine the application prospects of the devices.

[0003] In the related art, the chip structures of ultraviolet and deep ultraviolet LEDs are all layered stacked structures, that is, the n-type layer, quantum well layer, and p-type layer materials grow layer by layer along the c-axis from the substrate to the surface of the ultraviolet LED chip. After the ultraviolet LED chip with the above chip structure is connected to the circuit, the electrons provided by the n-type layer and the holes provided by the p-type layer migrate to the quantum well, and their transport direction is parallel to the growth direction and perpendicular to the chip surface; when the carriers recombine in the quantum well layer, ultraviolet light with different propagation directions is generated.

[0004] The UV LED chip with the above chip structure design has certain limitations. For example, the p-type aluminum gallium nitride layer with a high Al content in the UV LED chip is difficult to prepare and has problems such as poor conductivity. Even with the use of novel doping technologies such as gradient doping technology, its vertical conductivity is still worrying. The p-type layer with poor conductivity will lead to a decrease in the electrical injection efficiency and internal quantum efficiency of the UV LED chip.

[0005] The p-type layer currently used in UV LED chips is a p-type gallium nitride layer. Although its conductivity is better than that of the p-type aluminum gallium nitride layer with a high Al component, its narrow bandgap will absorb ultraviolet light emitted from the chip surface, resulting in a decrease in the light extraction efficiency and external quantum efficiency of the UV LED chip.

[0006] In addition, the active area of ​​the aluminum gallium nitride-based ultraviolet LED chip needs to use aluminum gallium nitride materials with a high Al content, and the TM wave is dominant in the ultraviolet light generated; the higher the Al content, the higher the proportion of TM waves; and its light emission direction tends to be lateral rather than along the growth direction. The ultraviolet light of the above-mentioned light emission method is difficult to collect and directly use, resulting in low light extraction efficiency and external quantum efficiency of the ultraviolet LED chip.

[0007] In summary, the UV LED chip structure in the related art cannot meet the device requirements of high light extraction rate, high light power, and high energy conversion efficiency. Therefore, it is of far-reaching significance to develop a new UV LED chip structure to improve related performance. Summary of the invention

[0008] In view of this, in order to solve at least one of the above and other technical problems in the related art, the present disclosure proposes a UV LED chip, including a substrate, a transition layer, an n-type aluminum gallium nitride layer, a p-type aluminum gallium nitride layer, an aluminum gallium nitride quantum well light-emitting layer and an electrode layer. Wherein, the transition layer is formed on the substrate; the n-type aluminum gallium nitride layer is formed in a first region on the transition layer, suitable for generating electrons in response to an external current; the p-type aluminum gallium nitride layer is formed in a second region on the transition layer spaced from the first region, suitable for generating holes in response to an external current; the aluminum gallium nitride quantum well light-emitting layer is formed on the transition layer and is located between the n-type aluminum gallium nitride layer and the p-type aluminum gallium nitride layer, including x barrier layers and x-1 potential well layers alternately arranged along a first direction, suitable for receiving electrons and holes transmitted laterally along the first direction, and allowing electrons and holes to recombine to generate ultraviolet light, wherein the first direction is a direction parallel to the substrate, 2≤x≤5; the electrode layer is formed on the n-type aluminum gallium nitride layer and the p-type aluminum gallium nitride layer, suitable for transmitting an external current.

[0009] According to an embodiment of the present disclosure, the transition layer includes an aluminum nitride buffer layer, an aluminum nitride single crystal layer, and an aluminum gallium nitride single crystal layer. The aluminum nitride buffer layer is formed on the substrate; the aluminum nitride single crystal layer is formed on the aluminum nitride buffer layer, and the aluminum nitride single crystal layer and the aluminum nitride buffer layer have the same aluminum content; the aluminum gallium nitride single crystal layer is formed on the aluminum nitride single crystal layer, and the aluminum content of the aluminum gallium nitride single crystal layer is less than that of the aluminum nitride single crystal layer.

[0010] According to an embodiment of the present disclosure, the aluminum content of the n-type aluminum gallium nitride layer is less than the aluminum content of the aluminum gallium nitride single crystal layer, and the aluminum content of the p-type aluminum gallium nitride layer gradually decreases along the second direction and the initial aluminum content is equal to the aluminum content of the aluminum gallium nitride single crystal layer, wherein the second direction is a direction perpendicular to the first direction and pointing from the substrate to the p-type aluminum gallium nitride layer.

[0011] According to an embodiment of the present disclosure, the aluminum content of the transition layer ranges from 80% to 100%.

[0012] According to an embodiment of the present disclosure, the aluminum content of the p-type aluminum gallium nitride layer ranges from 52% to 80%.

[0013] According to an embodiment of the present disclosure, the aluminum content of the barrier layer is greater than that of the potential well layer, and the bandgap width of the barrier layer is greater than the bandgap width of the potential well layer.

[0014] According to an embodiment of the present disclosure, the thicknesses of the n-type aluminum gallium nitride layer, the p-type aluminum gallium nitride layer, the barrier layer, and the well layer in the first direction are the same.

[0015] In another aspect of the present disclosure, a method for preparing the above-mentioned ultraviolet LED chip is proposed, comprising:

[0016] An aluminum nitride buffer layer, an aluminum nitride single crystal layer, and an aluminum gallium nitride single crystal layer are sequentially grown on the substrate to form a transition layer;

[0017] Growing n-type aluminum gallium nitride on the transition layer, etching the n-type aluminum gallium nitride so that the n-type aluminum gallium nitride is located in the first region of the transition layer, and obtaining an n-type aluminum gallium nitride layer;

[0018] Growing p-type aluminum gallium nitride in a second region spaced apart from the first region on the transition layer, and etching the p-type aluminum gallium nitride to obtain a p-type aluminum gallium nitride layer;

[0019] Alternately growing AlGaN with different aluminum contents between the n-type AlGaN layer and the p-type AlGaN layer on the transition layer as a barrier layer and a potential well layer;

[0020] An electrode layer is prepared on the n-type aluminum gallium nitride layer and the p-type aluminum gallium nitride layer by using a vapor deposition and annealing method.

[0021] According to an embodiment of the present disclosure, the growth method of p-type aluminum gallium nitride includes a gradient doping growth technology.

[0022] According to an embodiment of the present disclosure, the doped element includes magnesium, and the average concentration of magnesium doping is 6×10 18 cm -3 .

[0023] According to an embodiment of the present disclosure, the present disclosure proposes a UV LED chip with lateral carrier transmission, wherein lateral transmission refers to the transmission of holes or electrons in a direction parallel to the substrate (or the surface of the UV LED chip). Specifically, in the UV LED chip structure proposed in the present disclosure, the n-type aluminum gallium nitride layer, the p-type aluminum gallium nitride layer and the aluminum gallium nitride quantum well light-emitting layer are distributed perpendicular to the substrate direction, and the aluminum gallium nitride quantum well light-emitting layer is located between the n-type aluminum gallium nitride layer and the p-type aluminum gallium nitride layer. The p-type aluminum gallium nitride layer has good lateral hole transmission properties, which improves the electrical injection efficiency and internal quantum efficiency. At the same time, the aluminum gallium nitride quantum well light-emitting layer includes a plurality of barrier layers and potential well layers distributed at intervals, which improves the light extraction efficiency and the internal and external quantum efficiencies. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic cross-sectional view of the structure of an ultraviolet LED chip in an embodiment of the present disclosure;

[0025] Figure 2 is a flow chart of preparing a UV LED chip in an embodiment of the present disclosure;

[0026] Figure 3 is a schematic cross-sectional view of a UV LED chip substrate and a transition layer structure in an embodiment of the present disclosure;

[0027] Figure 4is a schematic cross-sectional view of the structure of the n-type aluminum gallium nitride layer of the ultraviolet LED chip in one embodiment of the present disclosure;

[0028] Figure 5 is a schematic cross-sectional view of a p-type aluminum gallium nitride layer structure of an ultraviolet LED chip in an embodiment of the present disclosure;

[0029] Figure 6 is a schematic cross-sectional view of a barrier layer structure of an ultraviolet LED chip in an embodiment of the present disclosure;

[0030] Figure 7 It is a schematic cross-sectional view of the potential well layer structure of the ultraviolet LED chip in one embodiment of the present disclosure.

[0031] In the above drawings, the meanings of the reference numerals are as follows:

[0032] 1. Substrate;

[0033] 21. Aluminum nitride buffer layer;

[0034] 22. Aluminum nitride single crystal layer;

[0035] 23. Aluminum gallium nitride single crystal layer;

[0036] 3. n-type aluminum gallium nitride layer;

[0037] 4. p-type aluminum gallium nitride layer;

[0038] 51. Barrier layer;

[0039] 52. Potential well layer;

[0040] 61. a first electrode;

[0041] 62. The second electrode. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0043] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this disclosure.

[0044] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0045] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0046] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present disclosure shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. If the full text involves descriptions such as "first", "second", etc., the descriptions such as "first", "second", etc. are only used to distinguish similar objects, and cannot be understood as indicating or implying their relative importance, order of precedence, or implicitly indicating the number of technical features indicated. It should be understood that the data described by "first", "second", etc. can be interchangeable under appropriate circumstances.

[0047] In the description of the present disclosure, it is necessary to understand that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the subsystem or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

[0048] Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure. The shapes, sizes, and positional relationships of the components in the drawings do not reflect the actual size, proportion, and actual positional relationship. In addition, in the present disclosure, any reference symbol between brackets should not be constructed as a limitation to the present disclosure.

[0049] Similarly, in order to simplify the present disclosure and help understand one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present disclosure, the various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. The description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0050] In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this disclosure.

[0051] In view of the fact that the vertical conductivity of the p-type aluminum gallium nitride material prepared by the gradient doping technology is not compatible with the vertically grown ultraviolet LED chip structure in the related art, the present disclosure proposes an ultraviolet LED chip in which the light-emitting area structure is evenly distributed perpendicular to the chip surface and the carriers are transmitted laterally. At the same time, in the present disclosure, on the one hand, the light-emitting direction during carrier recombination can be changed by regulating the crystal phase of the light-emitting area in the ultraviolet LED chip; on the other hand, by adjusting the structure around the light-emitting layer, there is no low aluminum content structure and low bandgap width components around it, thereby improving the light extraction efficiency and internal and external quantum efficiency of the ultraviolet LED chip.

[0052] Figure 1 It is a schematic cross-sectional view of the structure of an ultraviolet LED chip in one embodiment of the present disclosure.

[0053] The present disclosure proposes a UV LED chip, comprising a substrate 1, a transition layer, an n-type aluminum gallium nitride layer 3, a p-type aluminum gallium nitride layer 4, an aluminum gallium nitride quantum well light-emitting layer and an electrode layer. The transition layer is formed on the substrate 1; the n-type aluminum gallium nitride layer 3 is formed in a first region on the transition layer, and is suitable for generating electrons in response to an external current; the p-type aluminum gallium nitride layer 4 is formed in a second region on the transition layer spaced from the first region, and is suitable for generating holes in response to an external current; the aluminum gallium nitride quantum well light-emitting layer is formed on the transition layer and is located between the n-type aluminum gallium nitride layer 3 and the p-type aluminum gallium nitride layer 4, and comprises x potential barrier layers 51 and x-1 potential well layers 52 alternately arranged along a first direction, and is suitable for receiving electrons and holes transmitted laterally along the first direction, and allowing electrons and holes to recombine to generate ultraviolet light, wherein the first direction is a direction parallel to the substrate 1, 2≤x≤5; the electrode layer 6 is formed on the n-type aluminum gallium nitride layer 3 and the p-type aluminum gallium nitride layer 4, and is suitable for transmitting an external current.

[0054] According to the embodiments of the present disclosure, after the lateral ultraviolet LED chip in the present disclosure is connected to the circuit, the electrons provided by the n-type layer and the holes provided by the p-type layer migrate toward the quantum well, and their transport direction is perpendicular to the growth direction and parallel to the chip surface, which solves the limitations of traditional longitudinal ultraviolet LED chips.

[0055] According to an embodiment of the present disclosure, the present disclosure proposes a UV LED chip with lateral carrier transmission, wherein lateral transmission refers to the transmission of holes or electrons in a direction parallel to the substrate 1 (or the surface of the UV LED chip). Specifically, in the UV LED chip structure proposed in the present disclosure, the n-type aluminum gallium nitride layer 3, the p-type aluminum gallium nitride layer 4 and the aluminum gallium nitride quantum well light-emitting layer are distributed perpendicular to the substrate 1, and the aluminum gallium nitride quantum well light-emitting layer is located between the n-type aluminum gallium nitride layer 3 and the p-type aluminum gallium nitride layer 4. The p-type aluminum gallium nitride layer 4 has good lateral hole transmission properties, which improves the electrical injection efficiency and internal quantum efficiency. At the same time, the aluminum gallium nitride quantum well light-emitting layer includes a plurality of barrier layers 51 and potential well layers 52 that are spaced apart, which improves the light extraction efficiency and the internal and external quantum efficiencies.

[0056] According to an embodiment of the present disclosure, the transition layer includes an aluminum nitride buffer layer 21, an aluminum nitride single crystal layer 22, and an aluminum gallium nitride single crystal layer 23. The aluminum nitride buffer layer 21 is formed on the substrate 1; the aluminum nitride single crystal layer 22 is formed on the aluminum nitride buffer layer 21, and the aluminum nitride single crystal layer 22 and the aluminum nitride buffer layer 21 have the same aluminum content; the aluminum gallium nitride single crystal layer 23 is formed on the aluminum nitride single crystal layer 22, and the aluminum content of the aluminum gallium nitride single crystal layer 23 is less than the aluminum content of the aluminum nitride single crystal layer 22.

[0057] According to the embodiment of the present disclosure, the transition layer plays the role of supporting the ultraviolet LED chip and forming aluminum gallium nitride with a high aluminum content, wherein the aluminum nitride buffer layer 21 is aluminum nitride polycrystalline, which is conducive to synthesizing aluminum nitride single crystals with the same aluminum content to form an aluminum nitride single crystal layer 22. Similarly, aluminum nitride single crystals are conducive to synthesizing aluminum gallium nitride single crystals to obtain aluminum gallium nitride single crystal layer 23. An aluminum content gradient is formed layer by layer in the transition layer 2 along a direction perpendicular to the substrate 1, which is conducive to forming an n-type aluminum gallium nitride layer 3 and a p-type aluminum gallium nitride layer 4 with a high aluminum content component.

[0058] According to an embodiment of the present disclosure, the aluminum content of the n-type aluminum gallium nitride layer 3 is less than the aluminum content of the aluminum gallium nitride single crystal layer 23, and the aluminum content of the p-type aluminum gallium nitride layer 4 gradually decreases along the second direction and the initial aluminum content is equal to the aluminum content of the aluminum gallium nitride single crystal layer 23, wherein the second direction is a direction perpendicular to the first direction and pointing from the substrate 1 to the p-type aluminum gallium nitride layer 4.

[0059] According to the embodiments of the present disclosure, the p-type layer uses aluminum gallium nitride material with the advantage of wide bandgap width. At the same time, there is no narrow bandgap width gallium nitride layer or low Al component aluminum gallium nitride layer around the n-type aluminum gallium nitride layer 3, the p-type aluminum gallium nitride layer 4 and the aluminum gallium nitride quantum well light-emitting layer structure, so there is no situation where the ultraviolet light emitted from the surface of the light-emitting area in the horizontal ultraviolet LED chip structure is absorbed by the narrow bandgap width gallium nitride layer or the low Al component aluminum gallium nitride layer. The light extraction efficiency and external quantum efficiency of the ultraviolet LED chip are effectively improved. The aluminum content of the p-type aluminum gallium nitride layer 5 is designed to have good horizontal conductivity. The transport direction of the holes provided by the p-type aluminum gallium nitride layer 5 is perpendicular to the growth direction and parallel to the chip surface, and is laterally injected into the light-emitting area in the horizontal ultraviolet LED chip structure.

[0060] According to an embodiment of the present disclosure, the aluminum content of the transition layer varies in the range of 80% to 100%. For example, the aluminum content of the aluminum nitride buffer layer 21 can be 100%, the aluminum content of the aluminum nitride single crystal layer 22 is also 100%, and the aluminum content of the aluminum gallium nitride single crystal layer 23 is 80%.

[0061] According to the embodiment of the present disclosure, the aluminum content of the p-type aluminum gallium nitride layer 4 varies in the range of 52% to 80%. For example, the material of the p-type aluminum gallium nitride layer 4 is composed of Al with an Al component of 80%. 0.8 Ga 0.2 Al N material is graded to Al with Al content of 52% 0.52 Ga 0.48 N material.

[0062] According to an embodiment of the present disclosure, the aluminum content of the barrier layer 51 is greater than the aluminum content of the well layer 52 , and the bandgap width of the barrier layer 51 is greater than the bandgap width of the well layer 52 .

[0063] In some specific embodiments, the barrier layer 51 may be Al0.52 Ga 0.48 N, the potential well layer 52 can be Al 0.42 Ga 0.58 N.

[0064] According to the embodiments of the present disclosure, the barrier layer 51 and the well layer 52 in the lateral ultraviolet LED chip structure can grow along different crystal directions. In this way, the crystal type can be adjusted by controlling the growth conditions to adjust the surface and lateral light output ratio of the ultraviolet LED chip, and the surface and lateral light output will not be absorbed by other components, thereby improving the light extraction efficiency and external quantum efficiency of the ultraviolet LED chip.

[0065] According to an embodiment of the present disclosure, the thicknesses of the n-type aluminum gallium nitride layer 3 , the p-type aluminum gallium nitride layer 4 , the barrier layer 51 , and the well layer 52 in the first direction are the same.

[0066] Figure 2 It is a flow chart of the preparation of ultraviolet LED chips in the present disclosure.

[0067] Figure 3 to Figure 7 It is a schematic diagram of different structural cross-sections during the preparation process of the ultraviolet LED chip in one embodiment of the present disclosure.

[0068] In another aspect of the present disclosure, a method for preparing the above-mentioned ultraviolet LED chip is proposed, such as Figure 2 As shown, the following steps S1 to S5 are included:

[0069] Step S1: growing an aluminum nitride buffer layer 21, an aluminum nitride single crystal layer 22 and an aluminum gallium nitride single crystal layer 23 in sequence on a substrate 1 to form a transition layer.

[0070] In some specific embodiments, the substrate 1 may be a sapphire substrate.

[0071] Step S2: growing n-type aluminum gallium nitride on the transition layer, the structure of which is as follows Figure 3 As shown; the n-type aluminum gallium nitride is etched so that the n-type aluminum gallium nitride is located in the first region of the transition layer, thereby obtaining an n-type aluminum gallium nitride layer 3.

[0072] In some specific embodiments, the specific operation of step S2 is: first, a layer of photoresist is evenly spin-coated on the surface of the wafer having the substrate layer 1, the aluminum nitride buffer layer 21, the aluminum nitride single crystal layer 22, the aluminum gallium nitride single crystal layer 23, and the n-type aluminum gallium nitride layer 3, and a surface area of ​​the n-type aluminum gallium nitride layer 3 on one side is defined in the photoresist layer, and then inductively coupled plasma etching is performed, and then the residual photoresist is stripped off to obtain an n-type aluminum gallium nitride layer 3 arranged on one side of the aluminum gallium nitride single crystal layer 23, and its structure is as shown in FIG. Figure 4 shown.

[0073] Step S3: growing p-type aluminum gallium nitride in a second region spaced apart from the first region on the transition layer, and etching the p-type aluminum gallium nitride to obtain a p-type aluminum gallium nitride layer.

[0074] In some specific embodiments, the specific operation of step S3 is: first, a layer of photoresist is evenly spin-coated on the surface of the wafer after completing step S2, and a growth window area of ​​the p-type aluminum gallium nitride layer 4 on the other side is defined in the photoresist layer, and then a layer of SiO2 mask is deposited, and then the residual photoresist is stripped off, and then the p-type aluminum gallium nitride layer 4 is grown by gradient doping technology, and then inductively coupled plasma etching is performed, and then the SiO2 mask is stripped off to obtain the p-type aluminum gallium nitride layer 4 set on the other side of the aluminum gallium nitride single crystal layer 23. Its structure is as shown in FIG. Figure 5 shown.

[0075] Step S4: AlGaN with different aluminum contents is alternately regrown between the n-type AlGaN layer 3 and the p-type AlGaN layer 4 on the transition layer as the barrier layer 51 and the well layer 52 .

[0076] In some specific embodiments, the specific operation of growing the barrier layer 51 in step S4 is: first, a layer of photoresist is evenly spin-coated on the surface of the wafer after completing step S3, a growth window area of ​​the barrier layer 51 is defined in the photoresist layer, then a layer of SiO2 mask is deposited, then the residual photoresist is stripped, then the barrier layer 51 is grown, then inductively coupled plasma etching is performed, and then the SiO2 mask is stripped to obtain the barrier layer 51, whose structure is as shown in FIG. Figure 6 shown.

[0077] In some specific embodiments, the specific operation of growing the potential well layer 52 in step S4 is: first, a layer of photoresist is evenly spin-coated on the surface of the wafer after completing step S3, a growth window area of ​​the potential well layer 52 is defined in the photoresist layer, then a layer of SiO2 mask is deposited, then the residual photoresist is stripped, then the barrier layer 52 is grown, and then the SiO2 mask is stripped to obtain the potential well layer 52, whose structure is as shown in FIG. Figure 7 shown.

[0078] Step S5: preparing an electrode layer on the n-type aluminum gallium nitride layer 3 and the p-type aluminum gallium nitride layer 4 by evaporation and annealing.

[0079] In some specific embodiments, the specific operation of step S5 is: first, a layer of photoresist is evenly spin-coated on the surface of the wafer that has completed the S4 operation, and a contact area window area of ​​the electrode layer 6 is defined in the photoresist layer, and then 20nm Ni / 20nm Au is evaporated, and then a rapid annealing method is used to anneal at 500°C for 1min in an air atmosphere to obtain an electrode layer, and its structure is as follows: Figure 1 shown.

[0080] According to an embodiment of the present disclosure, the motor layer includes two electrodes, which are respectively disposed on the n-type aluminum gallium nitride layer 3 and the p-type aluminum gallium nitride layer 4 , and are respectively a first electrode 61 and a second electrode 62 .

[0081] According to an embodiment of the present disclosure, the growth method of p-type aluminum gallium nitride includes a gradient doping growth technology.

[0082] According to the embodiments of the present disclosure, the lateral transmission mode of the lateral ultraviolet LED chip structure is not only beneficial to the hole injection of the p-type aluminum gallium nitride layer of the gradient doping technology, but also beneficial to the hole injection of the p-type aluminum gallium nitride layer of the traditional doping mode, δ doping, metal modulation doping and other doping modes, thereby improving the electrical injection efficiency and the internal quantum efficiency.

[0083] According to an embodiment of the present disclosure, the doped element includes magnesium, and the average concentration of magnesium doping is 6×10 18 cm -3 .

[0084] It should be noted that the embodiments of the present disclosure use photoresist as the pattern transfer material, but this does not limit the protection scope of the present application. As long as the material can be used as the pattern transfer material, the technical solution of the present disclosure can be implemented.

[0085] It should be noted that the embodiments of the present disclosure adopt inductively coupled plasma etching, but this does not limit the protection scope of the present application. As long as the etching method can transfer the pattern to the underlying material, the technical solution of the present disclosure can be implemented.

[0086] It should be noted that the embodiment of the present disclosure uses SiO2 as a mask to form a growth window, but this does not limit the protection scope of the present application. As long as the material can be used as a mask, the technical solution of the present disclosure can be implemented.

[0087] It should be noted that the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present disclosure, other embodiments obtained by ordinary technicians in the field without creative work are all within the scope of protection of the present disclosure.

[0088] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A UV LED chip, comprising: substrate; A transition layer formed on the substrate; an n-type aluminum gallium nitride layer formed in a first region on the transition layer and adapted to generate electrons in response to an applied current; a p-type aluminum gallium nitride layer formed in a second region spaced apart from the first region on the transition layer and adapted to generate holes in response to an applied current; An aluminum gallium nitride quantum well light-emitting layer, formed on the transition layer and located between the n-type aluminum gallium nitride layer and the p-type aluminum gallium nitride layer, comprising x barrier layers and x-1 potential well layers alternately arranged along a first direction, adapted to receive the electrons and holes transversely transmitted along the first direction, and to allow the electrons and holes to recombine to generate ultraviolet light, wherein the first direction is a direction parallel to the substrate, and 2≤x≤5; The electrode layer is formed on the n-type aluminum gallium nitride layer and the p-type aluminum gallium nitride layer and is suitable for transmitting the external current.

2. The ultraviolet LED chip according to claim 1, wherein: The transition layer comprises: an aluminum nitride buffer layer formed on the substrate; an aluminum nitride single crystal layer, formed on the aluminum nitride buffer layer, the aluminum nitride single crystal layer and the aluminum nitride buffer layer having the same aluminum content; An aluminum gallium nitride single crystal layer is formed on the aluminum nitride single crystal layer, and the aluminum content of the aluminum gallium nitride single crystal layer is less than the aluminum content of the aluminum nitride single crystal layer.

3. The ultraviolet LED chip according to claim 2, wherein: The aluminum content of the n-type aluminum gallium nitride layer is less than the aluminum content of the aluminum gallium nitride single crystal layer, and the aluminum content of the p-type aluminum gallium nitride layer gradually decreases along a second direction and the initial aluminum content is equal to the aluminum content of the aluminum gallium nitride single crystal layer, wherein the second direction is a direction perpendicular to the first direction and pointing from the substrate to the p-type aluminum gallium nitride layer.

4. The ultraviolet LED chip according to claim 2, wherein: The aluminum content of the transition layer varies in the range of 80% to 100%.

5. The ultraviolet LED chip according to claim 1, wherein: The aluminum content of the p-type aluminum gallium nitride layer varies in the range of 52% to 80%.

6. The ultraviolet LED chip according to claim 1, wherein: The aluminum content of the barrier layer is greater than the aluminum content of the potential well layer, and the band gap width of the barrier layer is greater than the band gap width of the potential well layer.

7. The ultraviolet LED chip according to claim 1, wherein: The n-type aluminum gallium nitride layer, the p-type aluminum gallium nitride layer, the barrier layer, and the well layer have the same thickness in the first direction.

8. A method for preparing the ultraviolet LED chip according to any one of claims 1 to 7, comprising: An aluminum nitride buffer layer, an aluminum nitride single crystal layer, and an aluminum gallium nitride single crystal layer are sequentially grown on the substrate to form a transition layer; Growing n-type aluminum gallium nitride on the transition layer, and etching the n-type aluminum gallium nitride so that the n-type aluminum gallium nitride is located in a first region of the transition layer, thereby obtaining an n-type aluminum gallium nitride layer; Growing p-type aluminum gallium nitride in a second region spaced apart from the first region on the transition layer, and etching the p-type aluminum gallium nitride to obtain a p-type aluminum gallium nitride layer; Alternately growing aluminum gallium nitride with different aluminum contents between the n-type aluminum gallium nitride layer and the p-type aluminum gallium nitride layer on the transition layer as a barrier layer and a potential well layer; An electrode layer is prepared on the n-type aluminum gallium nitride layer and the p-type aluminum gallium nitride layer by using a vapor deposition and annealing method.

9. The method according to claim 8, wherein: The growth method of the p-type aluminum gallium nitride includes a gradient doping growth technology.

10. The method according to claim 9, wherein: The doped element includes magnesium, and the average concentration of the magnesium doped element is 6×10 18 cm -3 .

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