Brightness-reducing light-emitting diode and preparation method thereof

Abstract

The invention provides a brightness-reduced light-emitting diode and a preparation method thereof, and belongs to the technical field of photoelectron manufacturing. The light emitting diode comprises an epitaxial layer and a light absorption resistance increasing layer, the light absorption resistance increasing layer is located on one side of the epitaxial layer, and the light absorption resistance increasing layer comprises a metal oxide layer. According to the embodiment of the invention, the brightness of the light-emitting diode can be reduced and the working voltage of the light-emitting diode is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of optoelectronic manufacturing, and particularly to a light-emitting diode with reduced brightness and a preparation method thereof. Background Art

[0002] As a new product with great influence in the optoelectronic industry, a light-emitting diode (English: Light Emitting Diode, abbreviated as: LED) has the characteristics of small size, long service life, rich and colorful colors, low energy consumption, etc., and is widely used in the fields of lighting, display screens, signal lights, backlights, toys, etc.

[0003] In related technologies, terminals such as computer indicator lights and vehicle indicator lights also use light-emitting diodes as light sources. The light-emitting diode includes: an epitaxial layer, a transparent conductive layer, and an electrode. The transparent conductive layer is located on the surface of the epitaxial layer, and the transparent conductive layer has through holes. A part of the electrode is located in the through hole and is electrically connected to the epitaxial layer, and another part of the electrode is located on the transparent conductive layer. The electrode is used to connect to an external power supply and transmit current to various regions of the epitaxial layer.

[0004] Since terminals such as computer indicator lights and vehicle indicator lights have certain requirements for light-emitting diodes with low brightness and high voltage, usually, the size of the electrode is increased, and the light-emitting brightness is reduced by the light absorption of the large-size electrode. However, the method of changing the electrode size cannot achieve the purpose of changing the working voltage, so it is difficult to meet the use requirements of terminals such as computer indicator lights and vehicle indicator lights. Summary of the Invention

[0005] Embodiments of the present disclosure provide a light-emitting diode with reduced brightness and a preparation method thereof, which can reduce the brightness of the light-emitting diode and increase the working voltage of the light-emitting diode. The technical solution is as follows:

[0006] On the one hand, embodiments of the present disclosure provide a light-emitting diode, which includes an epitaxial layer and a light-absorbing and resistance-increasing layer. The light-absorbing and resistance-increasing layer is located on one side of the epitaxial layer, and the light-absorbing and resistance-increasing layer includes a metal oxide layer.

[0007] Optionally, the metal oxide layer includes at least one of a nickel oxide layer, a silver oxide layer, and a titanium oxide layer.

[0008] Optionally, the light-emitting diode further includes a transparent conductive layer located on the surface of the epitaxial layer, and the light-absorbing and resistance-increasing layer is located on the surface of the transparent conductive layer; the orthographic projection of the light-absorbing and resistance-increasing layer on the surface of the epitaxial layer is located within the orthographic projection of the transparent conductive layer on the surface of the epitaxial layer; or, the light-absorbing and resistance-increasing layer is further located on the surface of the epitaxial layer, and the orthographic projection of the transparent conductive layer on the surface of the epitaxial layer is located within the orthographic projection of the light-absorbing and resistance-increasing layer on the surface of the epitaxial layer.

[0009] Optionally, the light-emitting diode further includes a transparent conductive layer located on the surface of the epitaxial layer and covering the light-absorbing and resistance-increasing layer.

[0010] Optionally, the thickness of the light-absorbing and resistance-increasing layer is 20 angstroms to 200 angstroms.

[0011] Optionally, the light intensity of the light-emitting diode is less than or equal to 8.05 mW, and the operating voltage of the light-emitting diode is greater than or equal to 2.58 V.

[0012] Optionally, the epitaxial layer includes a first semiconductor layer, a multi-quantum well layer, and a second semiconductor layer stacked in sequence, and the light-absorbing and resistance-increasing layer is located on the second semiconductor layer; the ratio of the area of the orthographic projection of the light-absorbing and resistance-increasing layer on the surface of the first semiconductor layer to the area of the orthographic projection of the second semiconductor layer on the surface of the first semiconductor layer is greater than or equal to 0.3.

[0013] On the other hand, an embodiment of the present disclosure also provides a method for manufacturing a light-emitting diode, and the manufacturing method includes: forming an epitaxial layer; forming a light-absorbing and resistance-increasing layer on the epitaxial layer, and the light-absorbing and resistance-increasing layer includes a metal oxide layer.

[0014] Optionally, forming the light-absorbing and resistance-increasing layer on the epitaxial layer includes: forming a metal layer on the surface of the epitaxial layer; annealing the metal layer at a temperature of 350 °C to 650 °C so that the metal layer is oxidized into a metal oxide layer.

[0015] Optionally, after annealing the metal layer so that the metal layer is oxidized into a metal oxide layer, it further includes: etching the light-absorbing and resistance-increasing layer, and etching the light-absorbing and resistance-increasing layer with a mixed solution of FeCl3 and HCl for 0 s to 500 s.

[0016] The beneficial effects brought by the technical solution provided by the embodiment of the present disclosure at least include:

[0017] In the light-emitting diode provided by an embodiment of the present disclosure, a light-absorbing and resistance-increasing layer is provided on one side of the epitaxial layer. The light-absorbing and resistance-increasing layer includes a metal oxide layer, which can absorb part of the light emitted by the epitaxial layer, thus reducing the light transmittance and the luminous brightness of the light-emitting diode. At the same time, the metal oxide layer can increase the resistance. Since the total series resistance of the light-emitting diode increases, the working voltage will also increase accordingly to maintain the same working current. Therefore, the purpose of reducing the brightness and increasing the working voltage can be achieved, meeting the usage requirements of terminals such as computer indicator lights and vehicle indicator lights. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 is a top view of a light-emitting diode provided by an embodiment of the present disclosure;

[0020] Figure 2 is Figure 1 a provided AA cross-sectional view;

[0021] Figure 3 is a top view of another light-emitting diode provided by an embodiment of the present disclosure;

[0022] Figure 4 is Figure 3 a provided BB cross-sectional view;

[0023] Figure 5 is a top view of another light-emitting diode provided by an embodiment of the present disclosure;

[0024] Figure 6 is Figure 5 a provided CC cross-sectional view;

[0025] Figure 7 is a flowchart of a preparation method of a light-emitting diode provided by an embodiment of the present disclosure.

[0026] The descriptions of the marks in the drawings are as follows:

[0027] 10. Substrate;

[0028] 20. Epitaxial layer; 21. First semiconductor layer; 22. Multiple quantum well layer; 23. Second semiconductor layer;

[0029] 30. Light-absorbing and resistance-increasing layer;

[0030] 40. Transparent conductive layer;

[0031] 51. First electrode; 52. Second electrode;

[0032] 60. Passivation layer. Detailed implementation manners

[0033] To make the objectives, technical solutions and advantages of the present disclosure clearer, the following will further describe the embodiments of the present disclosure in detail with reference to the accompanying drawings.

[0034] Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the art to which the present disclosure pertains. The terms "first", "second", "third" and similar terms used in the specification and claims of the present patent application do not denote any order, quantity or importance, but are only used to distinguish different components. Similarly, the terms such as "a" or "one" do not denote a quantity limitation, but mean that there is at least one. The terms such as "comprising" or "including" mean that the elements or objects appearing before "comprising" or "including" cover the elements or objects listed after "comprising" or "including" and their equivalents, and do not exclude other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left", "right", "top", "bottom" are only used to indicate relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationships may also change accordingly.

[0035] Figure 1 is a top view of a light-emitting diode provided by an embodiment of the present disclosure. Figure 2 is Figure 1 a provided AA cross-sectional view. As Figure 1 、 2 shown, the light-emitting diode includes an epitaxial layer 20 and a light-absorbing and resistance-increasing layer 30, and the light-absorbing and resistance-increasing layer 30 is located on one side of the epitaxial layer 20.

[0036] Among them, the light-absorbing and resistance-increasing layer 30 includes a metal oxide layer.

[0037] In the embodiment of the present disclosure, a light absorption and resistance increasing layer 30 is provided on one side of the epitaxial layer 20. The light absorption and resistance increasing layer 30 includes a metal oxide layer, which can absorb part of the light emitted by the epitaxial layer 20 and can also reflect light, thus reducing the light transmittance and the luminous brightness of the light-emitting diode. At the same time, the metal oxide layer can increase the resistance. Since the total series resistance of the light-emitting diode increases, the operating voltage will also increase accordingly to maintain the same operating current. Therefore, the purpose of reducing the brightness and increasing the operating voltage can be achieved, meeting the usage requirements of terminals such as computer indicator lights and vehicle indicator lights.

[0038] Optionally, the metal oxide layer includes at least one of a nickel oxide layer, a silver oxide layer, and a titanium oxide layer.

[0039] Exemplarily, the metal oxide layer can be a nickel oxide layer. Nickel oxide is a wide-bandgap semiconductor with a bandgap of 3.6. Therefore, the introduction of the nickel oxide layer may significantly increase the series resistance in the circuit, which is beneficial to increasing the operating voltage of the light-emitting diode.

[0040] Moreover, the nickel oxide layer is green, so the nickel oxide layer will also absorb part of the light, further achieving the purpose of reducing the brightness of the light-emitting diode.

[0041] Exemplarily, the metal oxide layer can be a silver oxide layer. The conductivity of silver oxide will be greatly reduced, increasing the series resistance in the circuit, which is beneficial to increasing the operating voltage of the light-emitting diode.

[0042] Exemplarily, the metal oxide layer can be a titanium oxide layer. In addition to increasing the series resistance in the circuit and increasing the operating voltage of the light-emitting diode, the titanium oxide layer can also passivate the surface defect states of the epitaxial layer 20 and reduce the non-radiative recombination centers.

[0043] In some other implementation manners, the light absorption and resistance increasing layer 30 may further include a metal layer, and the metal layer is located on one side of the metal oxide layer.

[0044] Exemplarily, the metal layer is located between the metal oxide layer and the epitaxial layer, that is, the metal oxide layer is stacked on the metal layer.

[0045] Optionally, the metal layer includes at least one of a Ni layer, an Ag layer, and a Ti layer.

[0046] Exemplarily, the metal layer can be a Ni layer. In addition to being able to absorb part of the light, the Ni layer also has strong corrosion resistance and can effectively extend the service life of the light-emitting diode in a harsh environment.

[0047] Exemplarily, the metal layer can be an Ag layer. The high reflectivity of the Ag layer can effectively reflect the light generated by the epitaxial layer 20, thereby reducing the light output and increasing the number of reflections of the light within the epitaxial layer 20 for absorption. Moreover, Ag has a relatively high thermal conductivity, which helps to quickly conduct the heat generated by the light-emitting diode to the packaging substrate, improving the heat dissipation effect of the light-emitting diode.

[0048] Exemplarily, the metal layer can be a Ti layer. In addition to being able to absorb part of the light, the Ti layer can serve as part of the current spreading layer to help evenly distribute the current and avoid a decrease in efficiency or the formation of hot spots caused by too high local current density.

[0049] In one implementation of the present disclosure, the metal materials of the metal layer and the metal oxide layer can be the same metal.

[0050] As an example, the metal layer can be a Ni layer, and the metal oxide layer can be a NiO layer. When the metal layer and the metal oxide layer both use the same metal material, during the preparation process, after forming the metal layer, the local area of the metal layer far from the epitaxial layer is oxidized to obtain the metal oxide layer, which is convenient for quickly forming the light-absorbing and resistance-increasing layer.

[0051] In another implementation of the present disclosure, the metal materials of the metal layer and the metal oxide layer can be different metals.

[0052] As an example, the metal layer can be an Ag layer, and the metal oxide layer can be a NiO layer. The Ag layer has a higher reflectivity and can reflect most of the light, minimizing the light output to the greatest extent. The NiO layer can not only increase the series resistance in the circuit, which is beneficial to increasing the operating voltage of the light-emitting diode, but also the NiO layer is green, so the green NiO layer will also absorb part of the light, thereby further reducing the brightness of the light-emitting diode.

[0053] Optionally, as Figure 2 shown, the light-emitting diode further includes a transparent conductive layer 40. The transparent conductive layer 40 is located on the surface of the epitaxial layer 20, and the light-absorbing and resistance-increasing layer 30 is located on the surface of the transparent conductive layer 40.

[0054] As Figure 2 shown, the orthographic projection of the light-absorbing and resistance-increasing layer 30 on the surface of the epitaxial layer 20 is located within the orthographic projection of the transparent conductive layer 40 on the surface of the epitaxial layer 20.

[0055] In an embodiment of the present disclosure, the light-absorbing and resistance-increasing layer 30 is formed on the transparent conductive layer 40, and the Ni layer in the light-absorbing and resistance-increasing layer 30 is in contact with the transparent conductive layer 40. The Ni layer can serve as a physical barrier for metal diffusion, effectively preventing atoms in the subsequently deposited metal electrode from migrating to the transparent conductive layer 40. Moreover, a better ohmic contact can be formed between Ni and the transparent conductive layer 40. The work function of Ni has a high degree of matching with the work function of the transparent conductive layer 40, which can reduce the barrier height of carriers at the interface and improve the current injection efficiency.

[0056] Exemplarily, as Figure 2 shown, the orthographic projection of the light-absorbing and resistance-increasing layer 30 on the surface of the epitaxial layer 20 coincides with the orthographic projection of the transparent conductive layer 40 on the surface of the epitaxial layer 20.

[0057] In this way, the light-absorbing and resistance-increasing layer 30 completely covers the surface of the transparent conductive layer 40 away from the epitaxial layer 20, avoiding the sudden change of contact impedance in the uncovered area and ensuring uniform current injection on the entire surface of the device. For example, if the Ni layer is only located in a local area of the transparent conductive layer 40, the uncovered area on the transparent conductive layer 40 may cause current crowding due to poor ohmic contact, resulting in reduced efficiency and local heating.

[0058] Optionally, the transparent conductive layer 40 can be an indium tin oxide (ITO for short) or indium zinc oxide (IZO for short) layer. The ITO layer and IZO layer have good transmittance and low resistivity. Using the ITO layer and IZO layer as the transparent conductive layer 40 can allow more light to transmit through the transparent conductive layer 40, thus ensuring the light output effect; at the same time, due to the low resistivity, it is also convenient for carrier conduction and improves the injection efficiency.

[0059] As an example, the thickness of the transparent conductive layer 40 can be from 200 Å to 5000 Å. For example, the thickness of the transparent conductive layer 40 is 2000 Å.

[0060] Figure 3 is a top view of another light-emitting diode provided by an embodiment of the present disclosure. Figure 4 is Figure 3 a BB cross-sectional view provided. As Figure 3 , 4 shown, the light-emitting diode further includes a transparent conductive layer 40, the transparent conductive layer 40 is located on the surface of the epitaxial layer 20, and the light-absorbing and resistance-increasing layer 30 is located on the surface of the transparent conductive layer 40.

[0061] As Figure 4 shown, the light-absorbing and resistance-increasing layer 30 is also located on the surface of the epitaxial layer 20, and the orthographic projection of the transparent conductive layer 40 on the surface of the epitaxial layer 20 is within the orthographic projection of the light-absorbing and resistance-increasing layer 30 on the surface of the epitaxial layer 20.

[0062] As an example, as Figure 4 shown, in addition to being located on the transparent conductive layer 40, the light-absorbing and resistance-increasing layer 30 also extends to the surface of the epitaxial layer 20. That is, the light-absorbing and resistance-increasing layer 30 completely wraps the transparent conductive layer 40. After the light-absorbing and resistance-increasing layer 30 extends to the surface of the epitaxial layer 20, the area of the light-absorbing and resistance-increasing layer 30 can be effectively increased, thereby improving the light-absorbing area of the light-absorbing and resistance-increasing layer 30 and reducing the brightness of the light-emitting diode.

[0063] Moreover, the adhesion strength of NiO to the epitaxial material (such as GaN) is much higher than the adhesion strength of the transparent conductive layer 40 to the epitaxial material (such as GaN). By making the Ni layer also extend to the epitaxial layer 20, the connection stability between the transparent conductive layer 40 and the light-absorbing and resistance-increasing layer 30 and the epitaxial layer 20 can be improved.

[0064] Figure 5 is a top view of another light-emitting diode provided by an embodiment of the present disclosure. Figure 6 is Figure 5 a CC cross-sectional view provided. As Figure 5 , 6 shown, the light-emitting diode further includes a transparent conductive layer 40, the transparent conductive layer 40 is located on the surface of the epitaxial layer 20, and the transparent conductive layer 40 covers the light-absorbing and resistance-increasing layer 30.

[0065] As an example, as Figure 6 shown, in addition to being located on the light-absorbing and resistance-increasing layer 30, the transparent conductive layer 40 also extends to the surface of the epitaxial layer 20. That is, the transparent conductive layer 40 completely wraps the light-absorbing and resistance-increasing layer 30.

[0066] Among them, the transparent conductive layer 40 covers the light-absorbing and resistance-increasing layer 30, which can enhance the lateral current spreading and avoid current crowding.

[0067] Moreover, the NiO layer can absorb part of the light and reduce the brightness of the light-emitting diode; after the transparent conductive layer 40 wraps the NiO layer, it can fill the surface microstructure gaps.

[0068] Optionally, the thickness of the light-absorbing and resistance-increasing layer 30 is 20 Å to 200 Å.

[0069] Exemplarily, when the light-absorbing and resistance-increasing layer includes a metal layer and a metal oxide layer, the thickness ratio of the metal layer to the metal oxide layer in the light-absorbing and resistance-increasing layer 30 is 2 to 10.

[0070] As an example, if the thickness of the light-absorbing and resistance-increasing layer 30 is 100 Å and the thickness ratio of the metal layer to the metal oxide layer is 4, it can be determined that the thickness of the metal layer is 80 Å and the thickness of the metal oxide layer is 20 Å.

[0071] Optionally, as Figure 2As shown, the epitaxial layer 20 includes a first semiconductor layer 21, a multiple quantum well layer 22, and a second semiconductor layer 23 that are stacked in sequence. The light absorption and resistance increasing layer 30 is located on the second semiconductor layer 23.

[0072] Wherein, one of the first semiconductor layer 21 and the second semiconductor layer 23 is a p-type layer, and the other of the first semiconductor layer 21 and the second semiconductor layer 23 is an n-type layer.

[0073] Exemplarily, the first semiconductor layer 21 is an n-type layer, and the second semiconductor layer 23 is a p-type layer.

[0074] Optionally, the first semiconductor layer 21 is an n-type GaN layer doped with silicon. The thickness of the n-type GaN layer can be 0.5 μm to 3 μm.

[0075] Optionally, the multiple quantum well layer 22 includes alternately grown InGaN quantum well layers and GaN quantum barrier layers. Wherein, the multiple quantum well layer 22 can include 3 to 8 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0076] As an example, in the embodiments of the present disclosure, the multiple quantum well layer 22 includes 5 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0077] Optionally, the thickness of the multiple quantum well layer 22 can be 150 nm to 200 nm.

[0078] Optionally, the second semiconductor layer 23 is a p-type GaN layer doped with magnesium. The thickness of the p-type GaN layer can be 0.5 μm to 3 μm.

[0079] As Figure 2 shown, the light emitting diode further includes a substrate 10, and the epitaxial layer 20 is located on the surface of the substrate 10.

[0080] Exemplarily, the substrate can be a sapphire substrate. The sapphire substrate has a relatively high light transmittance, that is, the substrate is a transparent substrate. And the sapphire material is relatively hard and has relatively stable chemical properties, enabling the light emitting diode to have good light emitting effects and stability.

[0081] Optionally, the light emitting diode further includes an AlN buffer layer and a u-shaped GaN layer. The AlN buffer layer and the u-shaped GaN layer are sequentially stacked on the substrate, and the epitaxial layer 20 is located on the u-shaped GaN layer.

[0082] Among them, the ratio of the area of the light-absorbing and resistance-increasing layer 30 in the orthographic projection on the surface of the first semiconductor layer 21 to the area of the second semiconductor layer 23 in the orthographic projection on the surface of the first semiconductor layer 21 is greater than or equal to 0.3. In this way, the area of the light-absorbing and resistance-increasing layer 30 is made large enough so that a relatively large area of the light-absorbing and resistance-increasing layer 30 can be used to absorb light, which is beneficial to reducing the brightness of the light-emitting diode. Moreover, when the area of the light-absorbing and resistance-increasing layer 30 is relatively large, it can better disperse the current on the surface of the epitaxial layer 20, enabling the current to be more evenly distributed across the entire epitaxial layer 20 and reducing the phenomenon of local overheating.

[0083] Optionally, as Figure 2 shown, the light-emitting diode further includes a passivation layer 60, a first electrode 51, and a second electrode 52. The second semiconductor layer 23 further has a groove exposing the first semiconductor layer 21. The first electrode 51 is located in the groove and connected to the first semiconductor layer 21. A part of the second electrode 52 is located on the surface of the second semiconductor layer 23, and another part of the second electrode 52 is located on the light-absorbing and resistance-increasing layer 30. The first electrode 51 and the second electrode 52 are used to connect to an external power source and transmit current to various regions of the epitaxial layer 20.

[0084] As Figure 2 shown, the passivation layer 60 is located on the surface and in the groove of the second semiconductor layer 23, and covers the first electrode 51 and the second electrode 52. The passivation layer 60 further has through holes respectively exposing the first electrode 51 and the second electrode 52, so as to facilitate the connection of the external power source to the electrodes through the through holes.

[0085] Exemplarily, the passivation layer can be at least one of a silicon oxide layer, an aluminum oxide layer, and a silicon nitride layer.

[0086] Optionally, the thickness of the passivation layer can be 800 angstroms to 3000 angstroms.

[0087] Optionally, both the first electrode 51 and the second electrode 52 can include a first Al layer, a first Ti layer, a second Al layer, a second Ti layer, and an Au layer stacked in sequence.

[0088] The light-emitting diode provided by the embodiments of the present disclosure can absorb part of the light emitted by the epitaxial layer by arranging a light-absorbing and resistance-increasing layer on one side of the epitaxial layer with the help of a metal layer, so as to reduce the light transmittance and thus reduce the light-emitting brightness of the light-emitting diode. At the same time, by increasing the resistance through a metal oxide layer, the working voltage also increases accordingly to maintain the same working current. Thus, the purpose of reducing the brightness and increasing the working voltage is achieved, meeting the usage requirements of terminals such as computer indicator lights and vehicle indicator lights.

[0089] The following Table 1 is a comparison table of the optoelectronic properties of a light-emitting diode provided by the embodiments of the present disclosure.

[0090] Table 1

[0091]

[0092] In Table 1, Experimental Groups 1 to 5 are all light-emitting diodes provided in the embodiments of the present disclosure with a light-absorbing and resistance-increasing layer. According to the data provided in Table 1, it can be known that the light intensity of the light-emitting diodes in the embodiments of the present disclosure is less than or equal to 8.05 mW, and the operating voltage of the light-emitting diodes is greater than or equal to 2.58 V. Compared with the prior art, the light intensity of the light-emitting diodes in the embodiments of the present disclosure is on average reduced by 12.90%, and the operating voltage is on average increased by 0.099 V.

[0093] It can be seen that the light-emitting diodes provided in the embodiments of the present disclosure can not only reduce the brightness of the light-emitting diodes, but also increase the operating voltage of the light-emitting diodes, meeting the use requirements of terminals such as computer indicator lights and vehicle indicator lights.

[0094] Figure 7 is a flowchart of a method for manufacturing a light-emitting diode provided in an embodiment of the present disclosure. As Figure 7 shown, the manufacturing method includes:

[0095] S11: Form an epitaxial layer.

[0096] Among them, the epitaxial layer includes a first semiconductor layer, a multi-quantum well layer, and a second semiconductor layer stacked in sequence.

[0097] S12: Form a light-absorbing and resistance-increasing layer on the epitaxial layer.

[0098] Among them, the light-absorbing and resistance-increasing layer includes a metal oxide layer

[0099] The light-emitting diode manufactured by this manufacturing method is provided with a light-absorbing and resistance-increasing layer on one side of the epitaxial layer. Among them, the light-absorbing and resistance-increasing layer includes a metal oxide layer, and the metal oxide layer can absorb part of the light emitted by the epitaxial layer, thus reducing the light transmittance and thereby reducing the light-emitting brightness of the light-emitting diode. At the same time, the metal oxide layer can increase the resistance. Since the total series resistance of the light-emitting diode increases, the operating voltage will also increase accordingly to maintain the same operating current. Therefore, the purpose of reducing the brightness and increasing the operating voltage can be achieved, meeting the use requirements of terminals such as computer indicator lights and vehicle indicator lights.

[0100] To prepare Figure 2 the light-emitting diode shown as an example, the specific process of manufacturing the light-emitting diode is specifically described.

[0101] The epitaxial layer formed in step S11 is located on the substrate.

[0102] Among them, the substrate is a sapphire substrate, a silicon substrate, or a silicon carbide substrate. The substrate can be a flat substrate or a patterned substrate.

[0103] As an example, in the embodiments of the present disclosure, the substrate is a sapphire substrate. The sapphire substrate is a commonly used substrate with mature technology and low cost. Specifically, it can be a patterned sapphire substrate or a sapphire flat substrate.

[0104] Among them, the sapphire substrate can be pre-treated by placing the sapphire substrate in a MOCVD (Metal-organic Chemical Vapor Deposition) reaction chamber and baking the sapphire substrate for 12 minutes to 18 minutes. As an example, in the embodiments of the present disclosure, the sapphire substrate is baked for 15 minutes.

[0105] Specifically, the baking temperature can be 1000°C to 1200°C, and the pressure in the MOCVD reaction chamber during baking can be 100 mbar to 200 mbar.

[0106] Before step S11, it may include: sequentially forming an AlN buffer layer and a u-type GaN layer on the sapphire substrate by MOCVD technology.

[0107] Growing an epitaxial layer on the substrate in step S11 may include: sequentially forming a first semiconductor layer, a multi-quantum well layer, and a second semiconductor layer on the sapphire substrate by MOCVD technology.

[0108] Exemplarily, the epitaxial layer includes an n-type GaN layer, a multi-quantum well layer, and an n-type GaN layer stacked in sequence.

[0109] Optionally, the thickness of the n-type GaN layer can be 0.5 μm to 3 μm.

[0110] The growth temperature of the n-type GaN layer can be 1000°C to 1100°C, and the growth pressure of the n-type GaN layer can be 100 torr to 300 torr.

[0111] Optionally, the multi-quantum well layer includes alternately grown InGaN quantum well layers and GaN quantum barrier layers. Among them, the multi-quantum well layer can include 3 to 8 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0112] When growing the multi-quantum well layer, the pressure in the MOCVD reaction chamber is controlled at 200 torr. When growing the InGaN quantum well layer, the reaction chamber temperature is 760°C to 780°C. When growing the GaN quantum barrier layer, the reaction chamber temperature is 860°C to 890°C.

[0113] As an example, in the embodiments of the present disclosure, the multi-quantum well layer includes 5 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0114] Optionally, the thickness of the multi - quantum well layer can be from 150 nm to 200 nm.

[0115] Optionally, the thickness of the p - type GaN layer can be from 0.5 μm to 3 μm.

[0116] When growing the p - type GaN layer, the growth pressure of the p - type GaN layer can be from 200 Torr to 600 Torr, and the growth temperature of the p - type GaN layer can be from 800 °C to 1000 °C.

[0117] Step S12 can include the following steps:

[0118] In the first step, an etching groove is formed on the surface of the second semiconductor layer to expose the first semiconductor layer.

[0119] In the second step, a transparent conductive layer is formed on the surface of the second semiconductor layer.

[0120] Among them, the transparent conductive layer has a through - hole exposing the second semiconductor layer.

[0121] Exemplarily, the transparent conductive layer is an indium tin oxide layer or an indium zinc oxide layer.

[0122] Exemplarily, the thickness of the transparent conductive layer can be from 200 Å to 5000 Å. For example, the thickness of the transparent conductive layer is 2000 Å.

[0123] In the third step, a metal layer is formed on the surface of the epitaxial layer.

[0124] Exemplarily, the metal layer includes at least one of a Ni layer, an Ag layer, and a Ti layer.

[0125] Among them, the metal layer is located on the surface of the transparent conductive layer, and the orthographic projection of the light - absorbing and resistance - increasing layer on the surface of the epitaxial layer is located within the orthographic projection of the transparent conductive layer on the surface of the epitaxial layer.

[0126] In the fourth step, at a temperature of 350 °C to 650 °C, the metal layer is annealed so that the metal layer is oxidized into a metal oxide layer.

[0127] Exemplarily, the metal oxide layer includes at least one of a nickel oxide layer, a silver oxide layer, and a titanium oxide layer.

[0128] In the embodiments of the present disclosure, after forming the metal layer, by the process of high - temperature annealing of the metal layer, the metal layer can be completely oxidized to form a metal oxide layer, which is convenient for quickly forming the light - absorbing and resistance - increasing layer.

[0129] In the fifth step, the light - absorbing and resistance - increasing layer is etched, and the light - absorbing and resistance - increasing layer is corroded with a mixed solution of FeCl3 and HCl for 0 s to 500 s.

[0130] After etching the light-absorbing and resistance-increasing layer, some areas of the epitaxial layer are exposed, and it is also easy to leave some residues of the light-absorbing and resistance-increasing layer in the exposed areas of the epitaxial layer. Therefore, the remaining light-absorbing and resistance-increasing layer is etched and removed by a mixed solution of FeCl3 and HCl.

[0131] Step 6: Form a first electrode in the groove and a second electrode on the second semiconductor layer.

[0132] Among them, the first electrode located in the groove is an n-type electrode, and the one located on the second semiconductor layer is a p-type electrode.

[0133] Exemplarily, both the first electrode and the second electrode can be a first Al layer, a first Ti layer, a second Al layer, a second Ti layer, and an Au layer stacked in sequence.

[0134] Step 7: Form a passivation layer on the surface of the second semiconductor layer and in the groove.

[0135] Exemplarily, the passivation layer can be a silicon oxide layer, and the thickness of the passivation layer can be 800 angstroms to 3000 angstroms.

[0136] Optionally, the silicon oxide layer is stacked on the surface of the light-absorbing and resistance-increasing layer, the first electrode, and the second electrode.

[0137] Finally, the sapphire substrate can be invisibly cut and cleaved, and the invisible cutting and cleaving can preferably reduce the loss of brightness. Then, a light-emitting diode is obtained through testing.

[0138] The above are only optional embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A light emitting diode, characterized in that: The light emitting diode comprises an epitaxial layer (20) and a light absorption and resistance increasing layer (30), wherein the light absorption and resistance increasing layer (30) is located on one side of the epitaxial layer (20), and the light absorption and resistance increasing layer (30) comprises a metal oxide layer.

2. The light emitting diode according to claim 1, characterized in that: The metal oxide layer includes at least one of a nickel oxide layer, a silver oxide layer, and a titanium oxide layer.

3. The light emitting diode according to claim 1, characterized in that: The light emitting diode further comprises a transparent conductive layer (40), wherein the transparent conductive layer (40) is located on the surface of the epitaxial layer (20), and the light absorbing and resistance increasing layer (30) is located on the surface of the transparent conductive layer (40); The orthographic projection of the light-absorbing and resistance-increasing layer (30) on the surface of the epitaxial layer (20) is located within the orthographic projection of the transparent conductive layer (40) on the surface of the epitaxial layer (20); or, The light-absorbing and resistance-increasing layer (30) is also located on the surface of the epitaxial layer (20), and the orthographic projection of the transparent conductive layer (40) on the surface of the epitaxial layer (20) is located within the orthographic projection of the light-absorbing and resistance-increasing layer (30) on the surface of the epitaxial layer (20).

4. The light emitting diode according to claim 1, characterized in that: The light emitting diode further comprises a transparent conductive layer (40), wherein the transparent conductive layer (40) is located on the surface of the epitaxial layer (20) and covers the light absorbing and resistive increasing layer (30).

5. The light emitting diode according to any one of claims 1 to 4, characterized in that: The thickness of the light-absorbing and resistance-increasing layer (30) is 20 angstroms to 200 angstroms.

6. The light emitting diode according to any one of claims 1 to 4, characterized in that: The light intensity of the light emitting diode is less than or equal to 8.05 mW, and the operating voltage of the light emitting diode is greater than or equal to 2.58 V.

7. The light emitting diode according to any one of claims 1 to 4, characterized in that: The epitaxial layer (20) comprises a first semiconductor layer (21), a multi-quantum well layer (22), and a second semiconductor layer (23) stacked in sequence, and the light-absorbing and resistance-increasing layer (30) is located on the second semiconductor layer (23); The ratio of the area of ​​the orthographic projection of the light-absorbing and resistance-increasing layer (30) on the surface of the first semiconductor layer (21) to the area of ​​the orthographic projection of the second semiconductor layer (23) on the surface of the first semiconductor layer (21) is greater than or equal to 0.

3.

8. A method for preparing a light emitting diode, characterized in that: The preparation method comprises: forming an epitaxial layer; A light absorption and resistance increasing layer is formed on the epitaxial layer, wherein the light absorption and resistance increasing layer comprises a metal oxide layer.

9. The preparation method according to claim 8, characterized in that: Forming a light absorbing and resistance increasing layer on the epitaxial layer comprises: forming a metal layer on a surface of the epitaxial layer; The metal layer is annealed at a temperature of 350° C. to 650° C., so that the metal layer is oxidized into a metal oxide layer.

10. The preparation method according to claim 9, characterized in that: After annealing the metal layer so that the metal layer is oxidized into a metal oxide layer, the method further comprises: The light-absorbing and resistance-increasing layer is etched by using a mixed solution of FeCl 3 and HCl for 0 s to 500 s.

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