Reversed polarity light emitting diode and preparation method thereof

Abstract

The invention provides a reversed polarity light emitting diode and a preparation method thereof, and belongs to the technical field of photoelectron manufacturing. The light-emitting diode comprises an epitaxial structure, a first electrode, a second electrode and a metal reflecting layer, the epitaxial structure comprises a first semiconductor layer, a second semiconductor layer and a multi-quantum well layer located between the first semiconductor layer and the second semiconductor layer; the first electrode is connected with the first semiconductor layer, and the second electrode is connected with the second semiconductor layer; the metal reflecting layer is located on one side of the epitaxial structure, and the side wall of the metal reflecting layer is a roughened surface. According to the embodiment of the invention, the problem that the reflection effect becomes poor after the metal reflection layer is cut off can be improved, and the light-emitting brightness of the light-emitting diode is improved.

Description

Technical Field

[0001] This disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a reverse polarity light-emitting diode and its preparation method. Background Technology

[0002] Reverse polarity light-emitting diodes (LEDs) typically employ a vertical structure. A reverse polarity vertical LED comprises a substrate, a metal reflective layer, a transparent conductive layer, an insulating layer, and an epitaxial layer, stacked sequentially. A via is provided in the insulating layer to expose the transparent conductive layer, allowing the transparent conductive layer to be electrically connected to the epitaxial layer through the via.

[0003] In related technologies, in order to prevent Ag from migrating from the metal reflective layer and causing a decrease in reliability, the peripheral edges of the silver mirror reflective layer are usually cut off, and a protective layer is covered around the metal reflective layer to block Ag migration.

[0004] However, removing part of the metal reflective layer reduces its area, decreases its reflective effect, and affects the brightness of the LED. Summary of the Invention

[0005] This disclosure provides a reverse polarity light-emitting diode and its fabrication method, which can improve the problem of deteriorated reflection effect after the metal reflective layer is removed, and enhance the luminous brightness of the light-emitting diode. The technical solution is as follows: On one hand, this disclosure provides a light-emitting diode, which includes: an epitaxial structure, a first electrode, a second electrode, and a metal reflective layer; the epitaxial structure includes a first semiconductor layer, a second semiconductor layer, and a multi-quantum well layer located between the first semiconductor layer and the second semiconductor layer; the first electrode is connected to the first semiconductor layer, and the second electrode is connected to the second semiconductor layer; the metal reflective layer is located on one side of the epitaxial structure, and the sidewall of the metal reflective layer is a roughened surface.

[0006] Optionally, the thickness of the metal reflective layer is from 100 nm to 1000 nm.

[0007] Optionally, the epitaxial structure includes opposing first and second surfaces, with the orthographic projection of the metal reflective layer onto the first surface located within the first surface.

[0008] Optionally, the orthographic projection of the metal reflective layer on the first surface lies within the orthographic projection of the second surface on the first surface.

[0009] Optionally, the metal reflective layer is frustoconical, and the smaller end of the metal reflective layer is close to the epitaxial structure.

[0010] Optionally, the material used to prepare the metal reflective layer includes silver.

[0011] Optionally, the light-emitting diode further includes: an insulating layer and a transparent conductive layer, wherein the insulating layer is located between the epitaxial structure and the transparent conductive layer, and the transparent conductive layer is located between the insulating layer and the metal reflective layer; the insulating layer has a through-hole, and the transparent conductive layer contacts the epitaxial structure through the through-hole; the metal reflective layer and the transparent conductive layer are in direct contact.

[0012] Optionally, the light-emitting diode further includes a protective layer located on the side of the metal reflective layer away from the transparent conductive layer, and the protective layer encapsulates the metal reflective layer.

[0013] On the other hand, this disclosure also provides a method for fabricating a light-emitting diode, the method comprising: fabricating an epitaxial structure; fabricating a metal reflective layer on one side of the epitaxial structure; and roughening the sidewalls of the metal reflective layer.

[0014] Optionally, the thickness of the metal reflective layer is from 100 nm to 1000 nm.

[0015] The beneficial effects of the technical solutions provided in this disclosure include at least the following: The light-emitting diode of this disclosure roughens the sidewalls of the metal reflective layer. The roughening process creates microscopically uneven pits, protrusions, or etched textures on the sidewalls of the metal reflective layer. When light emitted from the epitaxial layer is transmitted to the sidewalls of the metal reflective layer, the microscopic uneven surface breaks the regular reflection path of the light, dispersing the light that might originally be scattered in a single direction to multiple angles, thus increasing the light emission angle. Moreover, the roughened surface increases the probability of light contact with the Ag reflective layer, that is, it increases the reflective area of ​​the metal reflective layer. This allows some of the light that hits the sidewalls of the metal reflective layer to be scattered by the roughened surface and then reflected back to the light emission surface, effectively improving the light emission brightness. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of this disclosure; Figure 2 This is a flowchart of a method for fabricating a light-emitting diode according to an embodiment of this disclosure; Figure 3This is a fabrication state diagram of a light-emitting diode provided in an embodiment of this disclosure; Figure 4 This is a fabrication state diagram of a light-emitting diode provided in an embodiment of this disclosure; Figure 5 This is an electron microscope comparison image of the metal reflective layer of a light-emitting diode provided in an embodiment of this disclosure.

[0018] The markings in the diagram are explained as follows: 10. Metal reflective layer; 11. Roughened surface; 20. Protective layer; 30. Epitaxial structure; 301. First surface; 302. Second surface; 31. Transparent conductive layer; 32. Insulating layer; 34. Conductive material block; 40. Bonding layer; 50. Conductive substrate; 61. First electrode; 62. Second electrode. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0020] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” “top,” and “bottom,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0021] Figure 1 This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of this disclosure. For example... Figure 1 As shown, the light-emitting diode includes: an epitaxial structure 30, a first electrode 61, a second electrode 62, and a metal reflective layer 10.

[0022] The epitaxial structure includes a first semiconductor layer, a second semiconductor layer, and a multi-quantum well layer located between the first semiconductor layer and the second semiconductor layer.

[0023] like Figure 1 As shown, the first electrode 61 is connected to the first semiconductor layer, and the second electrode 62 is connected to the second semiconductor layer.

[0024] like Figure 1 As shown, the metal reflective layer 10 is located on one side of the epitaxial structure 30, and the sidewall of the metal reflective layer 10 is a roughened surface 11.

[0025] The light-emitting diode of this disclosure roughens the sidewalls of the metal reflective layer. The roughening process creates microscopically uneven pits, protrusions, or etched textures on the sidewalls of the metal reflective layer. When light emitted from the epitaxial layer is transmitted to the sidewalls of the metal reflective layer, the microscopic uneven surface breaks the regular reflection path of the light, dispersing the light that might originally be scattered in a single direction to multiple angles, thus increasing the light emission angle. Moreover, the roughened surface increases the probability of light contact with the Ag reflective layer, that is, it increases the reflective area of ​​the metal reflective layer. This allows some of the light that hits the sidewalls of the metal reflective layer to be scattered by the roughened surface and then reflected back to the light emission surface, effectively improving the light emission brightness.

[0026] Optionally, the epitaxial structure 30 includes a first surface 301 and a second surface 302 opposite to each other, and the orthographic projection of the metal reflective layer 10 on the first surface 301 is located within the first surface 301. This ensures that the orthographic projection of the metal reflective layer is located on the surface of the epitaxial structure and does not extend beyond the edge of the epitaxial structure, thus preventing metal migration of the metal reflective layer in the edge region and its adhesion to the sidewall of the epitaxial structure, which would affect the reliability of the epitaxial structure.

[0027] Optionally, the orthographic projection of the metal reflective layer 10 on the first surface 301 lies within the orthographic projection of the second surface 302 on the first surface 301.

[0028] In this embodiment, the second surface 302 is etched to form grooves, which penetrate a portion of the multi-quantum-well layer in the epitaxial structure. Therefore, the regions in the epitaxial structure corresponding to the grooves do not actually emit light. In this embodiment, the orthographic projection of the metal reflective layer 10 on the backlight surface lies within the orthographic projection of the second surface 302 onto the first surface 301, that is, the orthographic projection of the metal reflective layer 10 lies within the orthographic projection of the light-emitting film layer in the epitaxial structure 30.

[0029] This arrangement, with the luminescent film layer facing the metal reflective layer, ensures that most of the light emitted perpendicularly from the luminescent film layer is reflected back to the direction of emission without loss. This prevents light from being absorbed or scattered by hitting gaps not covered by the silver mirror, thereby improving the efficiency of light energy recovery.

[0030] Optionally, such as Figure 1 As shown, the metal reflective layer 10 is frustoconical, and the smaller end of the metal reflective layer 10 is close to the epitaxial structure 30.

[0031] In the above implementation, the smaller end of the frustum-shaped structure is located on the first surface of the epitaxial structure 30, while the larger end is far away from the epitaxial structure 30. This stepped expansion, with a smaller top and a larger bottom, increases the actual reflective area between the metal reflective layer 10 and the epitaxial structure 30. Compared to the vertical sidewall of the metal reflective layer 10, the larger end of the frustum can cover a wider epitaxial light-emitting area, allowing more light from the epitaxial structure 30 to directly enter the sidewall of the metal reflective layer 10, reducing the proportion of light escaping from the device due to insufficient reflective layer area, thereby improving the initial light capture efficiency.

[0032] like Figure 1 As shown by the arrow in the optical path, the light rays from the epitaxial structure 30 are first incident perpendicularly to the small end of the frustum and directly reflected toward the light-emitting surface; while some of the light rays incident obliquely to the side wall of the frustum can be redirected to an angle closer to the light-emitting surface through one or more reflections, which can reduce the lateral scattering or absorption of light inside the device.

[0033] Optionally, the thickness of the metal reflective layer 10 is from 100 nm to 1000 nm.

[0034] For example, the thickness of the metal reflective layer 10 is 600 nm.

[0035] For example, the metal reflective layer 10 is made of silver, i.e., the metal reflective layer is a silver mirror reflective layer.

[0036] The reflectivity of silver in the visible light band increases with thickness. When the thickness of the metal reflective layer 10 reaches 100 nm or more, a continuous and dense metal film can be formed, with a reflectivity of over 95% for visible light. This efficiently reflects light emitted from the epitaxial structure, meeting the basic requirements of high-brightness LEDs for reflective layers. If the thickness is less than 100 nm, the silver film may have gaps or island structures due to insufficient continuity, leading to increased local light absorption and decreased reflectivity.

[0037] When the thickness of the metal reflective layer 10 exceeds 1000nm, although the reflectivity may be slightly improved, the excessively thick silver layer will significantly increase the material cost and is prone to cracking or peeling due to the accumulation of internal stress in the metal film, affecting the reliability of the device.

[0038] Optionally, such as Figure 1As shown, the light-emitting diode includes: a transparent conductive layer 31 and an insulating layer 32 located between the epitaxial structure 30 and the transparent conductive layer 31; the transparent conductive layer 31 is located between the insulating layer 32 and the metal reflective layer 10; the insulating layer 32 has a through hole, and the transparent conductive layer 31 contacts the epitaxial structure 30 through the through hole; the metal reflective layer 10 and the transparent conductive layer 31 are in direct contact.

[0039] like Figure 1 As shown, the insulating layer 32 has a through hole connecting the epitaxial structure 30 and the transparent conductive layer 31. The through hole is filled with a conductive material block 34, which is electrically connected to the transparent conductive layer 31 and the epitaxial structure 30, respectively.

[0040] For example, the transparent conductive layer 31 may be ITO or IZO.

[0041] For example, the insulating layer 32 may be a stacked silicon oxide layer, titanium oxide layer and silicon oxide layer.

[0042] In the example selection, the insulating layer 32 can be a silicon oxide layer or a titanium oxide layer.

[0043] For example, the conductive material block 34 may be at least one of indium tin oxide, indium zinc oxide, and metallic materials.

[0044] The conductive material block 34 within the via directly connects the epitaxial structure 30 and the transparent conductive layer 31, forming a low-resistance vertical conductive channel. This ensures that the driving current can be efficiently injected into the epitaxial structure 30 from the transparent conductive layer 31. The vertical via significantly reduces the resistance of the current transmission path, reduces Joule heat loss, and allows the current to diffuse more evenly to all areas of the epitaxial structure 30, avoiding localized overheating or current congestion, thus improving luminous efficiency and device lifespan.

[0045] In the epitaxial structure of this embodiment, one of the first semiconductor layer and the second semiconductor layer is a p-type layer, and the other of the first semiconductor layer and the second semiconductor layer is an n-type layer.

[0046] As an example, the first semiconductor layer is a p-type layer. The second semiconductor layer is an n-type layer.

[0047] Optionally, the first semiconductor layer is a p-type AlInP layer. The thickness of the p-type AlInP layer can be from 0.5 μm to 3 μm.

[0048] Optionally, the multiple quantum well layer includes alternating AlGaInP quantum well layers and AlGaInP quantum barrier layers. Specifically, the multiple quantum well layer may include 3 to 8 alternating stacked AlGaInP quantum well layers and AlGaInP quantum barrier layers.

[0049] As an example, in an embodiment of this disclosure, the multi-quantum-well layer includes five alternating stacked AlGaInP quantum-well layers and AlGaInP quantum-barrier layers.

[0050] Optionally, the thickness of the multi-quantum well layer can be from 150 nm to 200 nm.

[0051] Optionally, the second semiconductor layer is an n-type AlGaInP layer. The thickness of the n-type AlGaInP layer can be from 0.5 μm to 3 μm.

[0052] In this embodiment, electrodes are provided on both opposite sides of the epitaxial structure of the light-emitting diode (LED) to allow current to be injected into the LED through the electrodes. This type of LED is a vertical LED.

[0053] For example, such as Figure 1 As shown, a second electrode 62 is provided on the top surface of the epitaxial structure.

[0054] Optionally, the surface of the insulating layer 32 has a plurality of arrayed through holes, the orthographic projection of the through holes on the first surface being outside the orthographic projection of the second electrode 62 on the first surface.

[0055] In this embodiment, the surface of the epitaxial structure 30 near the second electrode 62 is the light-emitting surface, i.e., the first surface is the light-emitting surface. Since the second electrode 62 blocks light, placing the via in a position not opposite to the second electrode 62 allows more current to be transferred to the area of ​​the epitaxial structure 30 not opposite to the second electrode 62. This results in a higher luminous intensity in the area of ​​the epitaxial structure 30 not opposite to the second electrode 62, thereby improving the luminous efficiency of the light-emitting diode.

[0056] For example, such as Figure 1 As shown, the through-hole array is arranged. Setting multiple spaced through-holes allows current to be evenly transmitted through the conductive material block 34 inside the through-holes to all areas of the epitaxial structure 30, thereby improving the light-emitting effect of the light-emitting diode.

[0057] Optionally, such as Figure 1 As shown, the light-emitting diode also includes a protective layer 20, which is located on the side of the metal reflective layer 10 away from the transparent conductive layer 31, and the protective layer 20 covers the metal reflective layer 10.

[0058] The entire metal reflective layer 10 is completely covered by the protective layer 20. The protective layer 20 can directly block water, oxygen and electric field, suppressing Ag migration at the source, without having to increase the edge cut-off range to improve reliability.

[0059] For example, the protective layer can be a light-transmitting layer, which ensures that light penetrates and strikes the sidewall of the metal reflective layer 10 with low loss. Combined with the high reflectivity of Ag, this enables the light to form an efficient reflection cycle and expands the effective light emission angle.

[0060] As an example, the protective layer 20 includes an ITO or IZO layer, and the thickness of the protective layer 20 is greater than or equal to the thickness of the metal reflective layer 10.

[0061] In the above implementation, the thickness of the protective layer 20 reaches or exceeds that of the metal reflective layer 10. Its high conductivity can form a low-resistance electric field shielding layer around the metal reflective layer 10, effectively blocking the driving effect of the external electric field on Ag ions in the silver mirror layer. At the same time, the protective layer 20 covers the metal reflective layer 10, forming a dual protection of conductive shielding and physical barrier, further inhibiting Ag oxidation and migration caused by water and oxygen penetration.

[0062] The protective layer 20 is thicker than the metal reflective layer 10. The thicker protective layer 20 does not sacrifice light transmittance. Instead, the thicker film extends the scattering path of light within the protective layer 20. The longer propagation path gives light more opportunities to encounter inhomogeneities in the material (such as lattice defects, impurities, etc.), thereby increasing the probability of scattering.

[0063] Optionally, the thickness of the protective layer 20 is from 100 nm to 2000 nm.

[0064] For example, the thickness of the protective layer 20 is 1000 nm.

[0065] The protective layer 20 has a high transmittance for visible light. When the thickness is between 100nm and 2000nm, the overall transmittance can still be maintained above 85%, ensuring that light passes through the protective layer 20 without significant loss and participates in the reflection or light emission process. At the same time, a thickness of more than 100nm can effectively block water and oxygen penetration, preventing the silver mirror layer from oxidizing or migrating; a thickness within 2000nm can provide sufficient mechanical strength while avoiding stress mismatch caused by excessive thickness, ensuring the long-term reliability of the device and the stability of the process.

[0066] Optionally, such as Figure 1 As shown, the light-emitting diode also includes a bonding layer 40 and a conductive substrate 50, wherein the bonding layer 40, the conductive substrate 50 and the first electrode 61 are sequentially stacked on the surface of the protective layer 20 away from the epitaxial structure 30.

[0067] In this design, the conductive substrate 50 is connected to the protective layer 20 via the bonding layer 40, serving as the primary heat dissipation path for the device. The heat generated by the epitaxial structure 30, after being transferred to the conductive substrate 50 via the protective layer 20, rapidly diffuses to the external environment due to its high thermal conductivity, effectively reducing the chip junction temperature. This low junction temperature reduces thermal stress damage to critical structures such as the metal reflective layer 10 and the epitaxial structure 30, inhibits material performance degradation, thereby extending device lifespan and maintaining high brightness output.

[0068] Furthermore, the conductive substrate 50 not only serves as a heat dissipation layer but also acts as a carrier for the electrodes, connecting to the external driving circuit via the first electrode 61. The first electrode 61 provides a low-resistance, high-adhesion metal interface, ensuring that current can be uniformly injected from the conductive substrate 50 into the protective layer 20, avoiding localized overheating or electrical failure due to excessively high contact resistance. The robust bonding of the bonding layer 40 further ensures the mechanical stability of the conductive substrate 50 and the protective layer 20, preventing delamination or peeling during prolonged use.

[0069] Optionally, the bonding layer 40 includes at least one of a Ti layer, a Pt layer, an Au layer, and an In layer.

[0070] For example, the bonding layer 40 may be a Ti layer and an In layer stacked sequentially.

[0071] In this embodiment of the present disclosure, the In layer in the bonding layer 40 can utilize the good bonding performance of In to improve the bonding stability between the metal reflective layer 10 and the substrate.

[0072] As an example, in this embodiment of the disclosure, the conductive substrate 50 is a silicon substrate. Silicon substrates have good heat dissipation performance, are technologically mature, and are low in cost.

[0073] For example, the background layer may be at least one of a nickel layer and a gold layer.

[0074] Figure 2 This is a flowchart illustrating a method for fabricating a light-emitting diode (LED) according to an embodiment of this disclosure. This method is used to fabricate... Figure 1 The reverse polarity light-emitting diode shown. For example... Figure 2 As shown, the preparation method includes: S11: Fabrication of epitaxial structures.

[0075] S12: Fabricate a metallic reflective layer on one side of the epitaxial structure.

[0076] S13: Roughen the sidewalls of the metal reflective layer.

[0077] The sidewalls of the metal reflective layer are roughened.

[0078] The light-emitting diode prepared by this method roughens the sidewalls of the metal reflective layer 10, forming microscopically uneven pits, protrusions, or etched textures. When the light emitted from the epitaxial structure 30 is transmitted to the sidewalls of the metal reflective layer 10 through the protective layer 20, the microscopic uneven surface breaks the regular reflection path of the light, dispersing the light that might originally be scattered in a single direction to multiple angles, reducing the probability of light absorption. Moreover, the roughened surface 11 increases the contact probability between the light and the Ag reflective layer, so that some of the light that hits the sidewalls of the metal reflective layer 10 is scattered by the roughened surface 11 and reflected back to the light-emitting surface.

[0079] The preparation of the epitaxial structure 30 in step S11 may include the following steps: First step, such as Figure 3 As shown, an epitaxial structure 30 is formed on a GaAs wafer.

[0080] In this embodiment of the disclosure, the epitaxial structure 30 may include: a first semiconductor layer, a multiple quantum well layer, and a second semiconductor layer.

[0081] For example, the first semiconductor layer is a p-type layer and the second semiconductor layer is an n-type layer.

[0082] As an example, an n-type layer may include an n-type roughening layer, an n-type current spreading layer, and an n-type confinement layer.

[0083] As an example, a p-type layer may include: a p-type confinement layer, a p-type current spreading layer, a transition layer, and a p-type ohmic contact layer.

[0084] For example, the p-type confinement layer, the p-type current spreading layer, and the transition layer can all be AlInP layers.

[0085] For example, the p-type ohmic contact layer can be a p-type GaP layer.

[0086] The p-type GaP layer can be doped with Mg, with a Mg doping concentration of 1×10⁻⁶. 18 / cm 3 .

[0087] For example, the thickness of the p-type layer is 0.5 μm to 3 μm.

[0088] Optionally, the multi-quantum-well layer includes alternating AlGaInP quantum-well layers and AlGaInP quantum-barrier layers.

[0089] The multiple quantum well layer may include alternating stacked AlGaInP quantum well layers and AlGaInP quantum barrier layers with 3 to 8 cycles.

[0090] As an example, in an embodiment of this disclosure, the multi-quantum-well layer includes five alternating stacked AlGaInP quantum-well layers and AlGaInP quantum-barrier layers.

[0091] For example, the thickness of the multi-quantum well layer can be from 150 nm to 200 nm.

[0092] Optionally, the n-type roughening layer, the n-type current spreading layer, and the n-type confinement layer can all be n-type AlGaInP layers.

[0093] For example, the thickness of the n-type AlGaInP layer can be from 0.5 μm to 3 μm.

[0094] Specifically, this can include: growing an n-type roughening layer, an n-type current spreading layer, an n-type confinement layer, a multiple quantum well layer, a p-type confinement layer, a p-type current spreading layer, a transition layer, and a p-type ohmic contact layer using MOCVD. The second step, as Figure 3 As shown, a conductive material block 34 is formed on the surface of the epitaxial structure 30 away from the GaAs sheet.

[0095] Specifically, the process includes: depositing conductive material on a p-type ohmic contact layer, then spin-coating photoresist on its surface, exposing and developing it, creating a pattern with grooves on the photoresist, etching the conductive material, removing the photoresist, and creating the desired pattern, i.e., forming a conductive material block 34 in the groove.

[0096] Optionally, the conductive material block 34 includes at least one of indium tin oxide, indium zinc oxide, and metallic materials.

[0097] For example, the conductive material block 34 can be indium tin oxide.

[0098] For example, the thickness of the conductive material block 34 is 5 nm to 300 nm.

[0099] The third step, as Figure 3 As shown, an insulating layer 32 is formed on the surface of the epitaxial structure 30 away from the GaAs wafer and on the conductive material block 34.

[0100] The insulating layer 32 has through holes that expose the conductive material block 34.

[0101] Specifically, this includes: depositing an insulating layer 32 on the surface of the epitaxial structure 30, then spin-coating photoresist, exposing and developing the insulating layer 32 to form a through-hole exposing the epitaxial structure 30.

[0102] The insulating layer 32 may be at least one of a silicon oxide layer and a titanium oxide layer.

[0103] Step four, as Figure 3 As shown, a transparent conductive layer 31 is formed on the surface of the insulating layer 32 away from the GaAs sheet.

[0104] The transparent conductive layer 31 is electrically connected to the conductive material block 34.

[0105] For example, the transparent conductive layer 31 includes an indium tin oxide layer or an indium zinc oxide layer.

[0106] Specifically, this may include: forming a transparent conductive layer on the surface of the insulating layer 32 away from the GaAs wafer by sputtering the entire surface, so that the transparent conductive layer 31 and the conductive material block 34 form an ohmic contact.

[0107] For example, the thickness of the transparent conductive layer 31 can be from 2 nm to 500 nm.

[0108] Step S12, the process of preparing the metal reflective layer 10, may include the following steps: First, such as Figure 4 As shown, a metal reflective layer 10 is formed on the surface of the transparent conductive layer 31.

[0109] When forming the metal reflective layer 10, a metal layer can be formed on the surface of the transparent conductive layer by vapor deposition, followed by low-temperature annealing.

[0110] The metal layer can be a film made of metallic materials with good reflective properties, such as Ag and Cu.

[0111] Then, spin-coating photoresist, exposure, development, and removal of the peripheral edges of the metal reflective layer 10 using a stripping or etching process.

[0112] For example, the thickness of the metal reflective layer 10 is 100 nm to 1000 nm.

[0113] Next, as Figure 4 As shown, the metal reflective layer 10 is etched to make it into a frustum shape.

[0114] The smaller end of the metal reflective layer 10 is located on the back surface of the epitaxial structure 30.

[0115] Then, the sidewalls of the metal reflective layer 10 are oriented etched or chemically roughened to form a metal reflective layer 10 with only the sidewalls roughened.

[0116] like Figure 4 As shown, step S13 may include: depositing a transparent conductive material layer on the surface of the transparent conductive layer 31 by plasma-enhanced chemical vapor deposition or magnetron sputtering to form a protective layer 20 that completely covers the metal reflective layer 10 and its roughened sidewalls.

[0117] The following steps may also be included after step S13: First, a protective layer is formed on one side of the epitaxial structure, which covers the metal reflective layer.

[0118] Next, the protective layer 20 is bonded to the silicon substrate via the bonding layer 40.

[0119] Then, the GaAs wafer is removed, and a second electrode 62 is fabricated on the surface of the epitaxial structure 30; a first electrode 61 is fabricated on the silicon substrate.

[0120] Finally, the cutting process is carried out to produce individual core particles.

[0121] Table 1 below provides data on the light emission of LEDs.

[0122] Table 1

[0123] As shown in Table 1, after the sidewalls of the metal reflective layer are roughened, the average brightness of the light-emitting diode is 2.69% higher than that of the light-emitting diode without roughened sidewalls of the metal reflective layer. Therefore, the light-emitting diode provided in this embodiment can improve the problem of deteriorated reflection effect after the metal reflective layer is removed, and enhance the luminous brightness of the light-emitting diode.

[0124] Figure 5 These are electron microscope (EM) comparison images of the metal reflective layer of a light-emitting diode (LED) according to an embodiment of this disclosure. Figure 5 As shown in the figure, the left side illustrates a light-emitting diode with an unroughened sidewall of the metal reflective layer, while the right side illustrates a light-emitting diode with a roughened sidewall of the metal reflective layer. Figure 5 As shown, the roughened sidewalls of the metal reflective layer form microscopically uneven pits, protrusions, or etched textures. When light emitted from the epitaxial structure reaches the sidewalls of the metal reflective layer, the microscopic uneven surface breaks the regular reflection path of the light, dispersing the light that might have been scattered in a single direction to multiple angles, thus increasing the light emission angle. Combined with Table 1 above, and through comparison of experimental data, it can be seen that the brightness of the LED is higher after the sidewalls of the metal reflective layer are roughened.

[0125] The above description is merely an optional embodiment of this disclosure and is 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 light-emitting diode, characterized in that, The light-emitting diode includes: an epitaxial structure (30), a first electrode (61), a second electrode (62), and a metal reflective layer (10). The epitaxial structure includes a first semiconductor layer, a second semiconductor layer, and a multi-quantum-well layer located between the first semiconductor layer and the second semiconductor layer; The first electrode (61) is connected to the first semiconductor layer, and the second electrode (62) is connected to the second semiconductor layer; The metal reflective layer (10) is located on one side of the epitaxial structure (30), and the sidewall of the metal reflective layer (10) is a roughened surface (11).

2. The light-emitting diode according to claim 1, characterized in that, The thickness of the metal reflective layer (10) is 100 nm to 1000 nm.

3. The light-emitting diode according to claim 2, characterized in that, The epitaxial structure (30) includes a first surface and a second surface opposite to each other, and the orthographic projection of the metal reflective layer (10) on the first surface is located within the first surface.

4. The light-emitting diode according to claim 3, characterized in that, The orthographic projection of the metal reflective layer (10) on the first surface lies within the orthographic projection of the second surface on the first surface.

5. The light-emitting diode according to claim 4, characterized in that, The metal reflective layer (10) is frustoconical, and the smaller end of the metal reflective layer (10) is close to the epitaxial structure (30).

6. The light-emitting diode according to any one of claims 1 to 5, characterized in that, The metal reflective layer (10) is made of silver.

7. The light-emitting diode according to any one of claims 1 to 5, characterized in that, The light-emitting diode further includes an insulating layer (32) and a transparent conductive layer (31). The insulating layer (32) is located between the epitaxial structure (30) and the transparent conductive layer (31), and the transparent conductive layer (31) is located between the insulating layer (32) and the metal reflective layer (10). The insulating layer (32) has a through hole, and the transparent conductive layer (31) contacts the epitaxial structure (30) through the through hole. The metal reflective layer (10) and the transparent conductive layer (31) are in direct contact.

8. The light-emitting diode according to claim 7, characterized in that, The light-emitting diode further includes a protective layer (20), which is located on the side of the metal reflective layer (10) away from the transparent conductive layer (31) and the protective layer (20) wraps around the metal reflective layer (10).

9. A method for fabricating a light-emitting diode, characterized in that, The preparation method includes: Preparation of epitaxial structures; A metal reflective layer is prepared on one side of the epitaxial structure; The sidewalls of the metal reflective layer are roughened.

10. The preparation method according to claim 9, characterized in that, The thickness of the metal reflective layer is 100 nm to 1000 nm.

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