Algan-based ultraviolet light emitting device and method of manufacturing the same

Abstract

This disclosure provides a method for fabricating an AlGaN-based ultraviolet light-emitting device, comprising: operation S1: fabricating a flat AlN template on a substrate; operation S2: growing a recovery layer with a hexagonal protrusion surface morphology on the AlN template; operation S3: growing AlGaN in a three-dimensional pattern on the recovery layer to obtain a 3D-AlGaN layer with island-like protrusions; operation S4: growing n-type AlGaN in a two-dimensional pattern on the 3D-AlGaN layer to obtain a 2D-AlGaN layer; and operation S5: growing the functional layer of the ultraviolet light-emitting device on the 2D-AlGaN layer, thereby completing the fabrication of the ultraviolet light-emitting device. An AlGaN-based ultraviolet light-emitting device fabricated by the above method is also provided.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and in particular to an AlGaN-based ultraviolet light-emitting device and its fabrication method. Background Technology

[0002] Ultraviolet (UV) light-emitting devices based on AlGaN materials have broad application prospects in fields such as sterilization, biochemical detection, and solar-blind communication. Obtaining high-efficiency AlGaN-based UV light-emitting devices is a focus of attention for both academia and industry. Among these, the thin film quality of the n-type AlGaN layer has a significant impact on the device's quantum efficiency. n-type AlGaN requires a certain thickness for current spread. Currently, the growth of n-type AlGaN thin films is mainly based on AlN templates or AlN substrates. However, due to the lattice mismatch between AlGaN and AlN, AlGaN exhibits a certain compressive stress. As the thickness increases, this compressive stress accumulates, making it easier for dislocations to be added within the n-type AlGaN thin film to release the stress, thus degrading the quality of the n-type AlGaN thin film. Furthermore, the compressive stress in n-type AlGaN increases the hole injection barrier on the p-side of the light-emitting device, making hole injection more difficult and affecting the device's injection efficiency and quantum efficiency.

[0003] To address the aforementioned compressive stress problem, an AlN / AlGaN superlattice or an AlGaN layer with a gradient Al composition is typically inserted between AlN and n-type AlGaN to adjust the stress. However, this growth method has limited stress control; stress accumulation and partial release still occur when growing a certain thickness of n-type AlGaN, leading to dislocation multiplication. Moreover, the Al composition of n-type AlGaN grown using this method generally cannot be lower than 60%. Too low an Al composition results in excessive AlGaN stress, leading to surface roughness and poor film quality. Conversely, a higher Al composition in the n-type AlGaN layer increases contact resistance, resulting in higher device operating voltages. Summary of the Invention

[0004] To address the aforementioned problems, this disclosure provides an AlGaN-based ultraviolet light-emitting device and its fabrication method, thereby alleviating the technical issues described in the prior art.

[0005] (I) Technical Solution

[0006] One aspect of this disclosure provides a method for fabricating an AlGaN-based ultraviolet light-emitting device, comprising operations S1-S5, as follows:

[0007] Operation S1: Prepare a flat AlN template on the substrate;

[0008] Operation S2: A recovery layer with a hexagonal boss surface morphology is grown on the AlN template;

[0009] Operation S3: AlGaN is grown in a three-dimensional pattern on the recovery layer to obtain a 3D-AlGaN layer with island-shaped protrusions;

[0010] Operation S4: An n-type AlGaN layer is grown in a two-dimensional mode on the 3D-AlGaN layer to obtain a 2D-AlGaN layer; and

[0011] Operation S5: Grow the functional layer of the ultraviolet light-emitting device on the 2D-AlGaN layer to complete the fabrication of the ultraviolet light-emitting device.

[0012] Optionally, the substrate is made of sapphire or SiC; the recovery layer is made of AlN or AlGaN.

[0013] Optionally, the hexagonal boss is a raised structure with a hexagonal base and a flat top surface, wherein the width of the hexagonal boss is greater than 10 nm, the height is greater than 5 nm, and the density is greater than 10. 5 cm -2 .

[0014] Optionally, the 3D-AlGaN layer is configured for stress relief, generating dislocations; the 3D-AlGaN layer has a thickness of less than or equal to 3 μm and is doped with Si or not doped with Si.

[0015] Optionally, the 2D-AlGaN layer is configured for dislocation annihilation to further release stress, improve film quality, and enhance surface morphology. The thickness of the 2D-AlGaN layer is 1–10 μm; the doping element is Si, and the doping concentration is 10. 17 cm -3 ~10 21 cm -3 .

[0016] Optionally, the ultraviolet light-emitting device includes an ultraviolet light-emitting diode or an ultraviolet laser diode.

[0017] Optionally, the functional layer of the ultraviolet light-emitting diode, from bottom to top, includes: a single quantum well or multiple quantum well structure layer, an electron blocking layer, a pAlGaN hole transport layer, and a p-type contact layer;

[0018] The functional layers of the ultraviolet laser diode, from bottom to top, include: a lower waveguide layer, a single quantum well or multiple quantum well structure layer, an upper waveguide layer, an electron blocking layer, a pAlGaN optical confinement layer, and a p-type contact layer.

[0019] Optionally, the process for preparing a flat AlN template is selected from magnetron sputtering, MOCVD, HVPE or MBE.

[0020] Optionally, when using magnetron sputtering, an AlN layer with a thickness of 10 nm to 2 μm is obtained on the substrate by magnetron sputtering; then the sputtered AlN layer is annealed at high temperature in nitrogen; when using MOCVD, HVPE or MBE, a high-quality AlN film with a smooth surface is grown on the substrate using MOCVD, HVPE or MBE technology to obtain an AlN template with a thickness of 100 nm to 4 μm.

[0021] In another aspect, this disclosure provides an AlGaN-based ultraviolet light-emitting device, fabricated using any of the above-described fabrication methods. The ultraviolet light-emitting device, from bottom to top, comprises: a substrate; an AlN template; a recovery layer, the material of which is selected from AlN or AlGaN, having a hexagonal boss surface morphology; a 3D-AlGaN layer, configured to be formed on the 3D-AlGaN layer with island-shaped protrusions based on the hexagonal boss surface morphology; a 2D-AlGaN layer, configured to be fabricated on the 3D-AlGaN layer and fill between the island-shaped protrusions to form a flat surface; and a functional layer of the ultraviolet light-emitting device, the ultraviolet light-emitting device comprising an ultraviolet light-emitting diode or an ultraviolet laser diode.

[0022] (ii) Beneficial effects

[0023] As can be seen from the above technical solutions, the AlGaN-based ultraviolet light-emitting device and its fabrication method disclosed herein have at least one or a portion of the following beneficial effects:

[0024] (1) The n-type AlGaN is transformed into a two-dimensional planar growth after island merging, forming an atomically flat surface, with dislocations being annihilated in large quantities, which significantly improves the quality of the n-type AlGaN film;

[0025] (2) AlGaN-based ultraviolet light-emitting devices have high relaxation, which significantly improves photoelectric performance. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the fabrication method of an AlGaN-based ultraviolet light-emitting device according to an embodiment of this disclosure;

[0027] Figure 2 This is a schematic diagram illustrating the preparation process and structure of the recovery layer in Example 1.

[0028] Figure 3 This is a schematic diagram of the epitaxial structure of the AlGaN-based ultraviolet light-emitting diode according to Embodiment 1 of this disclosure;

[0029] Figure 4 This is a schematic diagram illustrating the preparation process and structure of the recovery layer in Embodiment 2 of this disclosure;

[0030] Figure 5This is a schematic diagram of the epitaxial structure of the AlGaN-based ultraviolet laser diode according to Embodiment 2 of this disclosure. Detailed Implementation

[0031] This disclosure provides an AlGaN-based ultraviolet light-emitting device and its fabrication method. First, an AlN or AlGaN thin layer is grown on an AlN template, with a certain density of hexagonal protrusions on its surface. During AlGaN growth, AlGaN first nucleates and grows on the hexagonal protrusions, resulting in three-dimensional island-like growth, which roughens the surface and fully releases stress, but generates a large number of dislocations. Then, the n-type AlGaN is transformed into a two-dimensional planar growth after island merging, forming an atomically flat surface. This significantly annihilates dislocations and greatly improves the quality of the n-type AlGaN thin film. Finally, an ultraviolet light-emitting device structure is grown on it, obtaining a high-relaxation AlGaN-based ultraviolet light-emitting device and improving its photoelectric performance.

[0032] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0033] In this disclosure, a method for fabricating an AlGaN-based ultraviolet light-emitting device is provided, combined with... Figure 1 and Figures 2-5 As shown, the fabrication method of the AlGaN-based ultraviolet light-emitting device includes:

[0034] Operation S1: Prepare a flat AlN template on the substrate;

[0035] Operation S2: A recovery layer with a hexagonal boss surface morphology is grown on the AlN template;

[0036] Operation S3: AlGaN is grown in a three-dimensional pattern on the recovery layer to obtain a 3D-AlGaN layer with island-shaped protrusions;

[0037] Operation S4: An n-type AlGaN layer is grown in a two-dimensional mode on the 3D-AlGaN layer to obtain a 2D-AlGaN layer; and

[0038] Operation S5: Grow the functional layer of the ultraviolet light-emitting device on the 2D-AlGaN layer to complete the fabrication of the ultraviolet light-emitting device.

[0039] According to embodiments of this disclosure, the substrate is made of sapphire or SiC; the recovery layer is made of AlN or AlGaN.

[0040] According to an embodiment of this disclosure, the hexagonal boss is a raised structure with a hexagonal bottom surface and a flat top surface. The width of the hexagonal boss is greater than 10 nm, the height is greater than 5 nm, and the density is greater than 10. 5 cm-2 .

[0041] According to embodiments of this disclosure, the 3D-AlGaN layer is configured for stress relief, generating dislocations; the 3D-AlGaN layer has a thickness of less than or equal to 3 μm and is doped with Si or not doped with Si.

[0042] According to embodiments of this disclosure, the 2D-AlGaN layer is configured for dislocation annihilation to further release stress, improve film quality, and enhance surface morphology. The thickness of the 2D-AlGaN layer is 1~10 μm; the doping element is Si, and the doping concentration is 10. 17 cm -3 ~10 21 cm -3 .

[0043] According to embodiments of this disclosure, the ultraviolet light-emitting device includes an ultraviolet light-emitting diode or an ultraviolet laser diode.

[0044] According to embodiments of this disclosure, the process for preparing a flat AlN template is selected from magnetron sputtering, MOCVD, HVPE, or MBE. When using magnetron sputtering, an AlN layer with a thickness of 10 nm to 2 μm is obtained on the substrate by magnetron sputtering; the sputtered AlN layer is then annealed at high temperature in nitrogen. When using MOCVD, HVPE, or MBE, a high-quality AlN film with a flat surface is grown on the substrate using MOCVD, HVPE, or MBE technology to obtain an AlN template with a thickness of 100 nm to 4 μm, and high-temperature nitrogen annealing can be selectively performed to further improve the quality of the AlN film.

[0045] According to an embodiment of this disclosure, the functional layer of an ultraviolet light-emitting diode, from bottom to top, includes: a single quantum well or multiple quantum well structure layer, an electron blocking layer, a pAlGaN hole transport layer, and a p-type contact layer;

[0046] According to embodiments of this disclosure, the functional layers of an ultraviolet laser diode, from bottom to top, include: a lower waveguide layer, a single quantum well or multiple quantum well structure layer, an upper waveguide layer, an electron blocking layer, a pAlGaN light confinement layer, and a p-type contact layer.

[0047] In another aspect, this disclosure provides an AlGaN-based ultraviolet light-emitting device, fabricated using the method described above, wherein the ultraviolet light-emitting device comprises, from bottom to top:

[0048] Substrate;

[0049] AlN template;

[0050] The recovery layer is prepared from AlN or AlGaN and has a hexagonal boss surface morphology.

[0051] A 3D-AlGaN layer is constructed based on the hexagonal boss surface morphology formed on a 3D-AlGaN layer with island-shaped protrusions;

[0052] A 2D-AlGaN layer is constructed on top of a 3D-AlGaN layer and fills the spaces between island-like protrusions to form a flat surface; and

[0053] The functional layer of an ultraviolet light-emitting device, wherein the ultraviolet light-emitting device includes an ultraviolet light-emitting diode or an ultraviolet laser diode.

[0054] Example 1

[0055] This explanation will take the fabrication of an ultraviolet light-emitting diode as an example, combined with... Figure 1 , Figure 2 and Figure 3 As shown, the core idea of ​​the high-relaxation-degree AlGaN-based ultraviolet light-emitting diode growth method mainly consists of three parts: First, growing an AlN thin film with a certain density of hexagonal protrusions on an AlN template; second, using a three-dimensional island-like growth method to roughen and release stress in AlGaN, then merging the islands and converting it into a two-dimensional n-type AlGaN growth to obtain a high-quality n-type AlGaN thick film; third, continuing to grow the various layers of the ultraviolet light-emitting diode structure. Specifically, this includes:

[0056] First, an AlN layer with a thickness of 10~2μm was obtained on a c-plane sapphire substrate by magnetron sputtering. A high-purity Al target (99.9999 at%) was selected, the substrate temperature range was 500℃~750℃, the atmosphere was nitrogen, the nitrogen flow rate was controlled at 50~500sccm, the RF sputtering power ranged from 500~3000W, and the deposition rate of the AlN film was 0.1~1 nm / s.

[0057] The sputtered AlN templates were placed face-to-face in an annealing furnace for high-temperature annealing to inhibit AlN decomposition. The annealing time was 1–20 h, the temperature range was controlled between 1600℃ and 1800℃, and the atmosphere was nitrogen.

[0058] Further, the prepared AlN / sapphire template is transferred to the MOCVD chamber, and the template surface is nitrided at a temperature of 1100~1300℃ in a hydrogen + ammonia atmosphere at a pressure not exceeding 100 mbar to obtain a smooth surface.

[0059] Furthermore, AlN with a lower V / Ⅲ ratio was used for quasi-homogeneous epitaxy, with a thickness of 200~1500 nm, a V / Ⅲ ratio of 1~100, a temperature of 1100~1300℃, and a pressure of 20~100 mbar, to obtain an AlN surface with hexagonal bosses.

[0060] Furthermore, three-dimensional growth of AlGaN is performed. The temperature, V / III ratio, and thickness are optimized based on the designed Al composition to achieve island-like growth on the surface. The temperature range is 1000~1150 ℃, the growth pressure is no higher than 100 mbar, and the thickness is preferably 500~3000 nm.

[0061] Furthermore, island merging and two-dimensional growth of n-type AlGaN are performed. The temperature, V / III ratio, and thickness are optimized based on the designed Al composition to transform island merging into two-dimensional growth, ultimately obtaining a smooth-surfaced thick n-type AlGaN film. The growth temperature range is 1000–1150 °C, the growth pressure is no higher than 100 mbar, and the preferred thickness is 1–5 μm. Excessively thick AlGaN films are prone to cracking during growth.

[0062] Next, the ultraviolet laser light-emitting diode structure is grown, and its structure is as follows: Figure 3 As shown, the high / low relationship of Al composition in each layer is indicated by the dark / light color. For example, the layers are ordered by the size of Al composition as follows: AlN template > recovery layer > 3D-AlGaN, 2D-nAlGaN layer, pAlGaN hole transport layer > quantum well active layer. The specific composition needs to be determined by simulating the device structure of each band.

[0063] First, the epitaxial uAl x Ga 1-x N / Al y Ga 1-y N single-quantum-well or multi-quantum-well structures, where 0 ≤ x < y ≤ 1; the thickness of the well and barrier within each period is 1~5 nm / 5~15 nm, containing 1~5 periodic structures. The quantum barrier can be doped with Si or not.

[0064] Furthermore, the epitaxial electron blocking layer is preferably 5-50 nm thick, and the Al composition must be higher than the quantum barrier in order to prevent electron leakage.

[0065] Furthermore, an epitaxial pAlGaN hole transport layer is included. This layer can be a single Al composition layer or an Al composition graded layer, preferably a single Al composition layer, with a thickness preferably of 10~200 nm. The dopant is Mg, and the doping concentration is 10. 17 ~10 21 cm -3 Or 10 18 ~10 20 cm -3 .

[0066] Furthermore, the epitaxial p-type contact layer, preferably with a thickness of 3-20 nm, is used as the ohmic contact for the p-type electrode. This layer can be a pAlGaN layer, a pGaN layer, or a pAlGaN / nAlGaN tunnel junction structure.

[0067] The scheme of this disclosure mainly induces rapid three-dimensional island growth of AlGaN by growing an AlN layer on an AlN template, forming hexagonal protrusions of a certain density on its surface, thereby releasing compressive stress. Then, two-dimensional growth of n-type AlGaN is continued, and the growth is converted to two-dimensional growth through island merging. During this process, dislocation merging and annihilation occur, further releasing stress, resulting in a high-quality, high-relaxation-degree AlGaN epitaxial film with a smooth surface. On this basis, an ultraviolet light-emitting diode device structure is epitaxially grown.

[0068] Example 2

[0069] A method for growing AlGaN-based ultraviolet laser diodes with high relaxation degree is provided, combined with Figure 1 , Figure 4 , Figure 5 As shown, the core idea mainly consists of three parts: first, growing an AlGaN thin film with a certain density of hexagonal protrusions on an AlN template; second, first growing AlGaN in a three-dimensional island pattern to roughen it and release stress, then merging the islands and converting it into a two-dimensional n-type AlGaN film to obtain a high-quality n-type AlGaN thick film; and third, continuing to grow the various layers of the ultraviolet laser diode structure. Specifically, this includes:

[0070] First, a high-quality AlN film with a smooth surface was grown on a c-plane sapphire substrate using MOCVD technology to obtain MO-AlN with a thickness of 100 nm to 4 μm.

[0071] Furthermore, AlGaN is directly grown on an AlN template with a thickness of 200~1500 nm, a V / Ⅲ ratio of 100~5000, a temperature of 1000~1150 ℃, and a pressure of 20~100 mbar to obtain an AlGaN surface with hexagonal bosses.

[0072] Furthermore, three-dimensional growth of AlGaN is performed. The temperature, V / III ratio, and thickness are optimized based on the designed Al composition to achieve island-like growth on the surface. The temperature range is 1000–1150 °C, the growth pressure is no higher than 100 mbar, and the preferred thickness is 500–3000 nm.

[0073] Furthermore, n-type AlGaN growth is performed to achieve island merging and two-dimensional growth. The temperature, V / III ratio, and thickness are optimized based on the designed Al composition to transform island merging into two-dimensional growth, dislocation annihilation, and ultimately obtain a high-quality n-type AlGaN thick film with a smooth surface. The growth temperature range is 1000–1150 °C, the growth pressure is no higher than 100 mbar, and the preferred thickness is 1–5 μm. Excessively thick AlGaN films are prone to cracking during growth.

[0074] Next, the epitaxial ultraviolet laser diode structure is shown in the figure. Figure 5 As shown, the high / low Al composition of each layer is indicated by the intensity of color. For example, the layers are ordered by Al composition as follows: AlN template ≥ electron blocking layer > pAlGaN optical confinement layer ≥ AlGaN recovery layer, 3D-AlGaN layer, 2D-nAlGaN optical confinement layer > uAlGaN upper waveguide layer, lower waveguide layer ≥ quantum well active region. The specific composition must be determined by simulating the device structure for each lasing band. Specifically, this includes:

[0075] Step 1, epitaxial uAl z Ga 1-z The N-type waveguide layer has a preferred thickness of 30-200 nm, and the Al composition must be lower than that of the aforementioned n-type AlGaN layer to provide optical confinement; the absence of dopants can reduce the loss of laser resonance.

[0076] Furthermore, the epitaxial uAl x Ga 1-x N / uAl y Ga 1-y N single-quantum-well or multi-quantum-well structures, where 0≤x<y≤z; the thickness of the well and barrier in each period is 1~5 nm / 5~15 nm, containing 1~5 periodic structures.

[0077] Furthermore, the epitaxial uAl z Ga 1-z The upper waveguide layer (N) has the same composition and thickness as the lower waveguide layer to improve the optical confinement factor.

[0078] Furthermore, the epitaxial electron blocking layer is preferably 10-30 nm thick, and the Al content must be higher than that of the waveguide layer in order to block electron leakage.

[0079] Furthermore, an epitaxial pAlGaN light confinement layer is formed, preferably an Al composition graded layer with a thickness of 200-600 nm. It can be p-type doped or undoped. The dopant is Mg with a doping concentration of 10. 17 ~10 21 cm -3 , or 10 18 ~10 21 cm -3 The spatial polarization charge generated by the gradual change in composition can be used to improve the hole activation effect of Mg.

[0080] Furthermore, the epitaxial p-type contact layer, preferably with a thickness of 3-20 nm, is used as the ohmic contact for the p-type electrode. This layer can be a pAlGaN layer, a pGaN layer, or a pAlGaN / nAlGaN tunnel junction structure.

[0081] The scheme of this disclosure mainly involves growing an AlGaN layer on an AlN template, forming hexagonal protrusions of a certain density on its surface to induce subsequent three-dimensional island growth of AlGaN and release compressive stress. Then, n-type AlGaN growth continues, and the growth is converted to two-dimensional growth through island merging. During this process, dislocation merging and annihilation occur, further releasing stress and achieving a high-quality, high-relaxation-degree AlGaN epitaxial film with a smooth surface. On this basis, an ultraviolet laser diode device structure is epitaxially grown.

[0082] According to embodiments of this disclosure, the epitaxial methods involved include MOCVD, HVPE, or MBE, etc.

[0083] The embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. It should be noted that implementations not illustrated or described in the drawings or the main text of the specification are forms known to those skilled in the art and are not described in detail. Furthermore, the definitions of the various elements and methods described above are not limited to the specific structures, shapes, or methods mentioned in the embodiments, and those skilled in the art can easily modify or substitute them.

[0084] Based on the above description, those skilled in the art should have a clear understanding of the AlGaN-based ultraviolet light-emitting device and its fabrication method disclosed herein.

[0085] In summary, this disclosure provides an AlGaN-based ultraviolet light-emitting device and its fabrication method. First, an AlN or AlGaN thin layer is grown on an AlN template, resulting in a surface with a certain density of hexagonal islands. During AlGaN growth, AlGaN first nucleates and grows on the hexagonal islands, resulting in three-dimensional island growth, which roughens the surface and fully releases stress, but generates a significant number of dislocations. Then, the n-type AlGaN is transformed into a two-dimensional planar growth through island merging, forming an atomically flat surface. This significantly annihilates dislocations and greatly improves the quality of the n-type AlGaN thin film. Finally, an ultraviolet light-emitting device structure is grown on it, obtaining a high-relaxation AlGaN-based ultraviolet light-emitting device and improving its photoelectric performance.

[0086] It should also be noted that the above are different embodiments provided by this disclosure. These embodiments are used to illustrate the technical content of this disclosure and are not intended to limit the scope of protection of this disclosure. A feature of one embodiment can be applied to other embodiments through suitable modifications, substitutions, combinations, or separations.

[0087] It should be noted that, unless otherwise specified herein, having "a" element is not limited to having a single element, but may include one or more of the element.

[0088] Furthermore, unless otherwise specified, the ordinal numbers such as "first," "second," etc., used herein are merely for distinguishing multiple elements with the same name and do not indicate any hierarchy, order of execution, or process sequence among them. A "first" element and a "second" element may appear together in the same component or separately in different components. The presence of an element with a higher ordinal number does not necessarily indicate the presence of another element with a lower ordinal number.

[0089] In this document, unless otherwise specified, the term "characteristic A" or "and / or" and "characteristic B" means that A exists alone, B exists alone, or A and B exist simultaneously; the term "characteristic A" and "and" or "and" and "and" and "characteristic B" means that A and B exist simultaneously; the terms "including", "containing", "having", and "containing" refer to, but are not limited to, these.

[0090] Furthermore, in this document, terms such as "up," "down," "left," "right," "front," "back," or "between" are used only to describe the relative positions of multiple elements and can be extended to include translation, rotation, or mirroring. Additionally, unless otherwise specified, the statement "one element is on another element" or similar statements do not necessarily indicate that the element is in contact with the other element.

[0091] Furthermore, unless specifically described or required to occur in a specific order, the order of the above steps is not limited to those listed above and can be varied or rearranged according to the desired design. Moreover, the above embodiments can be used in combination with each other or with other embodiments based on design and reliability considerations; that is, technical features from different embodiments can be freely combined to form more embodiments.

[0092] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A method for fabricating an AlGaN-based ultraviolet light-emitting device, comprising: Operation S1: Prepare a flat AlN template on the substrate; Operation S2: A recovery layer with a hexagonal boss surface morphology is grown on the AlN template; Operation S3: AlGaN is grown in a three-dimensional pattern on the recovery layer to obtain a 3D-AlGaN layer with island-shaped protrusions; Operation S4: An n-type AlGaN layer is grown in a two-dimensional mode on the 3D-AlGaN layer to obtain a 2D-AlGaN layer; and Operation S5: Grow the functional layer of the ultraviolet light-emitting device on the 2D-AlGaN layer to complete the fabrication of the ultraviolet light-emitting device.

2. The preparation method according to claim 1, wherein the substrate is prepared from sapphire or SiC; and the recovery layer is prepared from AlN or AlGaN.

3. According to the preparation method of claim 1, the hexagonal boss is a raised structure with a hexagonal bottom surface and a flat top surface, wherein the width of the hexagonal boss is greater than 10 nm, the height is greater than 5 nm, and the density is greater than 10. 5 cm -2 .

4. The preparation method according to claim 1, wherein the 3D-AlGaN layer is configured for stress relief and dislocation generation; the thickness of the 3D-AlGaN layer is less than or equal to 3 μm, and it is doped with Si or not doped with Si.

5. The preparation method according to claim 4, wherein the 2D-AlGaN layer is configured for dislocation annihilation to further release stress, improve film quality, and enhance surface morphology; the thickness of the 2D-AlGaN layer is 1~10 μm; the doping element is Si, and the doping concentration is 10. 17 cm -3 ~10 21 cm -3 .

6. The preparation method according to claim 1, wherein the ultraviolet light-emitting device comprises an ultraviolet light-emitting diode or an ultraviolet laser diode.

7. In the preparation method according to claim 1, in operation S1, the process for preparing the flat AlN template is selected from magnetron sputtering, MOCVD, HVPE or MBE.

8. According to the preparation method of claim 7, when magnetron sputtering is used, an AlN layer with a thickness of 10 nm to 2 μm is obtained on the substrate by magnetron sputtering; then the sputtered AlN layer is annealed at high temperature in nitrogen; when MOCVD, HVPE or MBE is used, a high-quality AlN film with a smooth surface is grown on the substrate by MOCVD, HVPE or MBE technology to obtain an AlN template with a thickness of 100 nm to 4 μm.

9. The preparation method according to claim 6, wherein, The functional layers of the ultraviolet light-emitting diode, from bottom to top, include: a single quantum well or multiple quantum well structure layer, an electron blocking layer, a pAlGaN hole transport layer, and a p-type contact layer; The functional layers of the ultraviolet laser diode, from bottom to top, include: a lower waveguide layer, a single quantum well or multiple quantum well structure layer, an upper waveguide layer, an electron blocking layer, a pAlGaN optical confinement layer, and a p-type contact layer.

10. An AlGaN-based ultraviolet light-emitting device, fabricated using the method described in any one of claims 1-9, wherein the ultraviolet light-emitting device comprises, from bottom to top: Substrate; AlN template; The recovery layer is prepared from AlN or AlGaN and has a hexagonal boss surface morphology. A 3D-AlGaN layer is constructed based on the hexagonal boss surface morphology formed on a 3D-AlGaN layer with island-shaped protrusions; A 2D-AlGaN layer is constructed on top of a 3D-AlGaN layer and filled between island-shaped protrusions to form a flat surface; as well as The functional layer of an ultraviolet light-emitting device, wherein the ultraviolet light-emitting device includes an ultraviolet light-emitting diode or an ultraviolet laser diode.

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