Light-emitting diode with improved brightness and method for preparing the same

Abstract

The present disclosure provides a light-emitting diode with improved brightness and a method for preparing the same, which belongs to the field of optoelectronic manufacturing technology. The light-emitting diode includes an epitaxial layer, the surface of the epitaxial layer has a groove, at least part of the surface of the groove is a rough surface, and the roughness of the rough surface is greater than the roughness of the surface of the epitaxial layer other than the groove. The embodiments of the present disclosure can improve the problem of a large amount of light being reflected back into the light-emitting diode, and improve the light extraction efficiency of the light-emitting diode.

Description

Technical Field

[0001] The present disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a light emitting diode with improved brightness and a preparation method thereof. Background Art

[0002] Light Emitting Diode (LED) is an extremely influential new product in the optoelectronics industry. It has the characteristics of small size, long service life, rich colors and low energy consumption. It is widely used in lighting, display screens, signal lights, backlight sources, toys and other fields.

[0003] In the related art, a light-emitting diode includes a substrate, an epitaxial layer and an electrode, wherein the epitaxial layer is stacked on the substrate. The epitaxial layer generally includes a plurality of stacked semiconductor layers. A groove is also provided in a part of the epitaxial layer to expose a part of the semiconductor layer in the epitaxial layer, so that an electrode is formed in the groove to facilitate power supply to the semiconductor layer.

[0004] When the light emitted by the LED passes through the substrate, semiconductor layer and electrode, there will be photon loss. When the light reaches the semiconductor layer and the air interface, a large part of the photons are reflected back into the semiconductor due to reflection and refraction. This results in low light extraction efficiency and low brightness of the LED. Summary of the invention

[0005] The embodiments of the present disclosure provide a light emitting diode with improved brightness and a method for manufacturing the same, which can improve the problem of a large amount of light being reflected back into the light emitting diode and enhance the light extraction efficiency of the light emitting diode. The technical solution is as follows:

[0006] On the one hand, an embodiment of the present disclosure provides a light-emitting diode, which includes an epitaxial layer, wherein the surface of the epitaxial layer has a groove, at least a portion of the surface of the groove is a rough surface, and the roughness of the rough surface is greater than the roughness of the surface of the epitaxial layer except the groove.

[0007] In one implementation of the present disclosure, the side wall of the groove is the rough surface, and in the direction from the opening of the groove to the bottom of the groove, the rough surface includes a first inclined surface and a second inclined surface connected in sequence, and the roughness of the first inclined surface is less than the roughness of the second inclined surface.

[0008] In another implementation of the present disclosure, the surface of the first inclined surface has a plurality of first protrusions arranged at intervals, and the surface of the second inclined surface has a plurality of second protrusions arranged at intervals; the number of the first protrusions distributed per unit area is greater than the number of the second protrusions distributed per unit area, and the maximum width of the first protrusion is smaller than the maximum width of the second protrusion.

[0009] In another implementation of the present disclosure, the inclination angle of the first inclined surface is greater than the inclination angle of the second inclined surface.

[0010] In another implementation of the present disclosure, the epitaxial layer includes a first semiconductor layer, a multi-quantum well layer, and a second semiconductor layer stacked in sequence, the groove is located on a surface of the second semiconductor layer away from the first semiconductor layer, and the groove at least exposes the multi-quantum well layer; the rough surface includes at least the side wall of the multi-quantum well layer exposed by the groove.

[0011] In another implementation of the present disclosure, the light-emitting diode further includes a passivation layer, which is located on the surface of the epitaxial layer and in the groove, and the surface roughness of the passivation layer in the groove is greater than the surface roughness of the passivation layer outside the groove.

[0012] In another implementation of the present disclosure, the groove includes at least one of an isolation groove and an electrode groove.

[0013] On the other hand, an embodiment of the present disclosure also provides a method for preparing a light-emitting diode, the method comprising: forming an epitaxial layer; forming a groove on the surface of the epitaxial layer, at least a portion of the surface of the groove is a rough surface, and the roughness of the rough surface is greater than the roughness of the surface of the epitaxial layer except the groove.

[0014] Optionally, forming a groove on the surface of the epitaxial layer includes: etching the surface of the epitaxial layer to form a groove; controlling the temperature of the reaction chamber to 25° C. to 90° C., and soaking the epitaxial layer in alkaline solution for 1 min to 2 h to roughen the surface of the groove.

[0015] Optionally, the alkali solution is a KOH solution, and the concentration of the KOH solution is 20wt% to 55wt%.

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

[0017] The light-emitting diode provided by the embodiment of the present disclosure sets at least part of the surface of the groove of the epitaxial layer as a rough surface, and the roughness of the rough surface is greater than the roughness of the surface outside the groove on the epitaxial layer. That is, the surface of the groove is made rougher. Since the light emitted from the epitaxial layer of the groove on the smooth surface is more easily reflected or totally reflected at the junction of the smooth surface and the air or other film layers. Compared with the groove on the smooth surface, the groove on the rough surface used in the embodiment of the present disclosure disrupts the movement path of the light when the light is emitted to the rough surface, thereby reducing the reflection of the light and allowing more light to escape, thereby improving the light extraction efficiency of the light-emitting diode and improving the brightness of the light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 is a structural schematic diagram of a light emitting diode provided by an embodiment of the present disclosure;

[0020] Figure 2 is a schematic diagram of the structure of a groove provided by an embodiment of the present disclosure;

[0021] Figure 3 is a structural schematic diagram of a light emitting diode provided by an embodiment of the present disclosure;

[0022] Figure 4 is a schematic diagram of groove distribution of an epitaxial layer provided by an embodiment of the present disclosure;

[0023] Figure 5 It is a flow chart of a method for preparing a light emitting diode provided in an embodiment of the present disclosure.

[0024] The descriptions of the marks in the figure are as follows:

[0025] 10. Substrate;

[0026] 20. epitaxial layer; 21. first semiconductor layer; 22. multi-quantum well layer; 23. second semiconductor layer;

[0027] 30, groove; 31, rough surface; 311, first inclined surface; 312, second inclined surface; 313, first protrusion; 314, second protrusion;

[0028] 40. Passivation layer;

[0029] 50. Current blocking layer;

[0030] 60. Transparent conductive layer;

[0031] 70. Electrode;

[0032] 81. Isolation slot; 82. Electrode slot. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0034] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The words "first", "second", "third" and similar words used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", "top", "bottom" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0035] Figure 1 Schematic diagram of the structure of a light emitting diode provided by an embodiment of the present disclosure. Figure 1 As shown, the light emitting diode comprises an epitaxial layer 20 , and a surface of the epitaxial layer 20 has a groove 30 .

[0036] In the embodiment of the present disclosure, at least a portion of the surface of the groove 30 is a rough surface 31 . That is, the rough surface 31 may be the entire surface or a portion of the surface of the groove 30 .

[0037] Exemplarily, the groove 30 includes a sidewall and a groove bottom connected to the sidewall. When the rough surface 31 is a partial surface of the groove 30, the rough surface 31 can be the sidewall or the groove bottom of the groove 30, or the rough surface 31 can be a partial sidewall or a partial groove bottom of the groove 30.

[0038] Exemplarily, when the rough surface 31 is the entire surface, the rough surface 31 includes the sidewalls and the bottom of the groove 30 .

[0039] The roughness of the rough surface is greater than the roughness of the surface of the epitaxial layer except the groove.

[0040] In the light-emitting diode provided by the embodiment of the present disclosure, at least part of the surface of the groove 30 of the epitaxial layer 20 is set as a rough surface 31, and the roughness of the rough surface 31 is greater than the roughness of the surface outside the groove 30 on the epitaxial layer 20. That is, the surface of the groove 30 is made rougher. Due to the smooth surface of the groove 30, the light emitted from the epitaxial layer 20 is more easily reflected or totally reflected at the interface between the smooth surface and the air or other film layers.

[0041] Compared with the groove 30 on the smooth surface, the groove 30 on the rough surface 31 used in the embodiment of the present disclosure is Figure 1 As shown by the arrow in the light path, when the light is emitted to the rough surface 31, the movement path of the light is disrupted, thereby reducing the reflection of the light and allowing more light to escape, thereby improving the light extraction efficiency of the LED and improving the brightness of the LED.

[0042] Figure 2 Schematic diagram of the structure of a groove 30 provided in an embodiment of the present disclosure. Figure 2 As shown, the side wall of the groove 30 is a rough surface 31. From the opening of the groove 30 to the bottom of the groove 30, the rough surface 31 includes a first inclined surface 311 and a second inclined surface 312 connected in sequence. The roughness of the first inclined surface 311 is less than the roughness of the second inclined surface 312.

[0043] Since the light-emitting film layer of the epitaxial layer 20 is usually distributed in the middle area of ​​the epitaxial layer 20, most of the light is concentrated in the middle area. The embodiment of the present disclosure sets two connected inclined surfaces and makes the lower second inclined surface 312 rougher. That is, the rougher inclined surface is opposite to the light-emitting film layer of the epitaxial layer 20, so that most of the light emitted from the epitaxial layer 20 can be directed to the rougher inclined surface, and the rougher second inclined surface 312 is used to make it easier for the light to escape, thereby improving the light extraction efficiency of the light-emitting diode.

[0044] Alternatively, if Figure 2 As shown, the surface of the first inclined surface 311 has a plurality of first protrusions 313 arranged at intervals, and the surface of the second inclined surface 312 has a plurality of second protrusions 314 arranged at intervals.

[0045] The number of first protrusions 313 distributed per unit area is greater than the number of second protrusions 314 distributed per unit area. That is, the distribution density of the first protrusions 313 is greater than the distribution density of the second protrusions 314. The first protrusions 313 are more densely distributed on the first inclined surface 311, while the second protrusions 314 are more sparsely distributed on the second inclined surface 312.

[0046] The maximum width of the first protrusion 313 is smaller than the maximum width of the second protrusion 314. The maximum width of the first protrusion 313 may be the distance between the two farthest points on the outer surface of the first protrusion 313, and the maximum width of the second protrusion 314 may be the distance between the two farthest points on the outer surface of the second protrusion 314.

[0047] In the embodiment of the present disclosure, the size of the first protrusions 313 is smaller, and the distribution of the first protrusions 313 is more dense, which makes the gaps between adjacent first protrusions 313 smaller; while the size of the second protrusions 314 is larger, and the distribution of the second protrusions 314 is more sparse, which makes the gaps between adjacent second protrusions 314 larger. Therefore, the first inclined surface 311 is flatter than the second inclined surface 312 as a whole, that is, the roughness of the second inclined surface 312 is greater than the roughness of the first inclined surface 311. In this way, the second inclined surface 312 is made rougher, so that most of the light emitted from the epitaxial layer 20 can be directed to the rougher inclined surface, and the rougher second inclined surface 312 is used to make it easier for the light to escape, thereby improving the light extraction efficiency of the light-emitting diode.

[0048] Exemplarily, the first protrusion 313 may be a polygonal pyramid, a polygonal column, a cylinder, a cone, a sphere, or an ellipsoid. For example, the first protrusion 313 may be a sphere.

[0049] Exemplarily, the second protrusion 314 may be a polygonal pyramid, a polygonal column, a cylinder, a cone, a sphere, or an ellipsoid. For example, the second protrusion 314 may be a hexagonal pyramid.

[0050] Alternatively, if Figure 2 As shown, the inclination angle of the first inclined surface 311 is greater than the inclination angle of the second inclined surface 312 .

[0051] The inclination angle of the first inclined surface 311 refers to the angle between the first inclined surface 311 and the bottom surface or the top surface of the epitaxial layer 20. The inclination angle of the second inclined surface 312 refers to the angle between the second inclined surface 312 and the bottom surface or the top surface of the epitaxial layer 20. For example,

[0052] The top surface and the bottom surface of the epitaxial layer 20 are two opposite surfaces on the epitaxial layer 20. For example, the groove 30 is located on the top surface of the epitaxial layer 20.

[0053] Exemplarily, the inclination angle of the first inclined surface 311 is 45° to 90°. For example, the inclination angle of the first inclined surface 311 is 60°.

[0054] Exemplarily, the inclination angle of the second inclined surface 312 is less than or equal to 45°. For example, the inclination angle of the second inclined surface 312 is 30°.

[0055] In the above implementation, the first inclined surface 311 is made steeper, so that part of the light passing through the first inclined surface 311 is more likely to be emitted laterally, while the second inclined surface 312 is made flatter, so that part of the light passing through the second inclined surface 312 is more likely to be emitted vertically. In this way, light can be emitted from different directions, improving the light emitting effect of the light emitting diode.

[0056] Alternatively, if Figure 1As shown, the epitaxial layer 20 includes a first semiconductor layer 21 , a multi-quantum well layer 22 and a second semiconductor layer 23 stacked in sequence, the groove 30 is located on the surface of the second semiconductor layer 23 away from the first semiconductor layer 21 , and the groove 30 at least exposes the multi-quantum well layer 22 .

[0057] For example, Figure 1 As shown, the groove 30 exposes the first semiconductor layer 21 .

[0058] In the disclosed embodiment, the rough surface 31 includes at least the side wall of the multi-quantum well layer 22 exposed by the groove 30. Since the multi-quantum well layer 22 is the light-emitting region of the epitaxial layer 20, the light is mostly concentrated in the region where the multi-quantum well layer 22 is located. In this way, setting the side wall of the multi-quantum well layer 22 corresponding to the groove 30 as the rough surface 31 is conducive to using the rough surface 31 to make it easier for light to escape, thereby improving the light extraction efficiency of the light-emitting diode.

[0059] For example, Figure 1 As shown, the second inclined surface includes the side wall of the multi-quantum well layer 22 exposed by the groove 30. Since the multi-quantum well layer is the film layer with the largest light emission of the light-emitting diode, the side wall of the multi-quantum well layer is located at the position of the second inclined surface, so that the side wall of the multi-quantum well layer has a larger roughness, which can minimize the reflection of light and improve the light extraction rate.

[0060] For example, Figure 3 As shown, the first inclined surface includes the sidewall of the multi-quantum well layer 22 exposed by the groove 30, that is, the sidewall of the multi-quantum well layer is located at the position of the first inclined surface. This allows more light to be transmitted from the first inclined surface to improve the lateral light emission of the light-emitting diode.

[0061] Alternatively, if Figure 1 As shown, the light emitting diode includes a substrate 10 , and an epitaxial layer 20 is located on the surface of the substrate 10 .

[0062] For example, the substrate may be a sapphire substrate. The sapphire substrate has a relatively high light transmittance, that is, the substrate is a transparent substrate. In addition, the sapphire material is relatively hard and has relatively stable chemical properties, so that the light-emitting diode has good light-emitting effect and stability.

[0063] Optionally, 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.

[0064] Exemplarily, the first semiconductor layer 21 is an n-type layer, and the second semiconductor layer 23 is a p-type layer.

[0065] Optionally, the first semiconductor layer 21 is a silicon-doped n-type GaN layer, and the thickness of the n-type GaN layer may be 0.5 μm to 3 μm.

[0066] Optionally, the multi-quantum well layer 22 includes alternately grown InGaN quantum well layers and GaN quantum barrier layers, wherein the multi-quantum well layer 22 may include 3 to 8 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0067] As an example, in the embodiment of the present disclosure, the multi-quantum well layer 22 includes five periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0068] Optionally, the thickness of the multi-quantum well layer 22 may be 150 nm to 200 nm.

[0069] Optionally, the second semiconductor layer 23 is a magnesium-doped p-type GaN layer. The thickness of the p-type GaN layer may be 0.5 μm to 3 μm.

[0070] Optionally, the light emitting diode further includes an AlN buffer layer and a u-type GaN layer, the AlN buffer layer and the u-type GaN layer are sequentially stacked on the substrate, and the epitaxial layer 20 is located on the u-type GaN layer.

[0071] Alternatively, if Figure 1 As shown, a current blocking layer 50 and a transparent conductive layer 60 are also provided on the surface of the epitaxial layer 20. The current blocking layer 50 is located on the surface of the second semiconductor layer 23 away from the first semiconductor layer 21. The transparent conductive layer 60 is located on the surface of the second semiconductor layer 23 away from the first semiconductor layer 21, and the transparent conductive layer 60 covers the current blocking layer 50.

[0072] Usually, an electrode 70 is disposed above the current blocking layer 50 , so as to prevent the current injected by the electrode 70 from being directly injected vertically downward into the epitaxial layer 20 , thereby causing the problem of excessive local voltage.

[0073] Exemplarily, the current blocking layer 50 may be a silicon oxide layer, and the thickness of the current blocking layer 50 is 200 angstroms to 3000 angstroms.

[0074] Optionally, the transparent conductive layer 60 may be an indium tin oxide (ITO) layer or an indium zinc oxide (IZO) layer. The ITO layer and the IZO layer have good transmittance and low resistivity, which can allow more light to be transmitted from the transparent conductive layer 60, thereby 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.

[0075] As an example, the thickness of the transparent conductive layer 60 may be 200 angstroms to 5000 angstroms. For example, the thickness of the transparent conductive layer 60 is 2000 angstroms.

[0076] Alternatively, if Figure 1As shown, the light emitting diode further includes a passivation layer 40 , which is located on the surface of the epitaxial layer 20 and in the groove 30 . The surface roughness of the passivation layer 40 in the groove 30 is greater than the surface roughness of the passivation layer 40 outside the groove 30 .

[0077] In the embodiment of the present disclosure, the passivation layer 40 located in the groove 30 is attached to the rough surface 31, so the passivation layer 40 is also uneven as a whole. In this way, when light is emitted from the passivation layer 40, it can also disrupt the movement path of the light, thereby reducing the reflection of the light, allowing more light to escape, thereby improving the light extraction efficiency of the light-emitting diode and improving the brightness of the light-emitting diode.

[0078] Optionally, the thickness of the passivation layer 40 is less than or equal to 3000 angstroms.

[0079] By setting the thickness of the passivation layer 40 within the above range, the thickness of the passivation layer 40 is prevented from being too thick, so that the passivation layer 40 cannot form an uneven shape after being attached to the rough surface 31 .

[0080] Optionally, the thickness of the passivation layer 40 may be greater than or equal to 800 angstroms. This can also prevent the passivation layer 40 from being too thin and being torn and broken by the protrusions on the rough surface 31 after being attached to the rough surface 31, thereby improving the reliability of the passivation layer 40.

[0081] Exemplarily, the thickness of the passivation layer 40 is 1000 angstroms.

[0082] Optionally, the passivation layer 40 may be at least one of a silicon oxide layer, an aluminum oxide layer, and a silicon nitride layer.

[0083] Figure 4 FIG. 2 is a schematic diagram of the distribution of grooves 30 of an epitaxial layer 20 provided in an embodiment of the present disclosure. Figure 1 , 4 As shown, an isolation groove 81 is opened at the peripheral edge of the epitaxial layer 20 , the isolation groove 81 exposes the first semiconductor layer 21 , and an electrode groove 82 is opened in the central area of ​​the epitaxial layer 20 , the electrode groove 82 is used to accommodate the electrode 70 .

[0084] Optionally, the groove 30 includes at least one of an isolation groove 81 and an electrode groove 82. Exemplarily, the groove 30 includes both the isolation groove 81 and the electrode groove 82, which can maximize the light extraction efficiency of the light emitting diode.

[0085] Alternatively, if Figure 1 As shown, the light emitting diode also includes two electrodes 70 , one portion of the electrode 70 is located in the groove 30 and connected to the first semiconductor layer 21 exposed by the groove 30 , and the other portion of the electrode 70 is located on the passivation layer 40 and connected to the transparent conductive layer 60 through the through hole of the passivation layer 40 .

[0086] Illustratively, the electrode may include a first Al layer, a first Ti layer, a second Al layer, a second Ti layer, and an Au layer stacked in sequence.

[0087] Table 1 below is a brightness difference table of a light emitting diode provided by an embodiment of the present disclosure. As can be seen from Table 1, the average brightness change of the light emitting diode of the embodiment of the present disclosure and the light emitting diode in the related art is 0.56%. It can be seen that the light emitting diode provided by the embodiment of the present disclosure can effectively improve the light extraction efficiency of the light emitting diode and improve the light emitting brightness of the light emitting diode.

[0088] Table 1

[0089] condition wavelength brightness Brightness change% Voltage base1 453.26 140.87 base 2.80 Experimental Group 1 452.72 141.43 0.40％ 2.80 base2 453.83 144.03 base 2.81 Experimental Group 2 453.53 144.90 0.61％ 2.80 base3 454.40 142.30 base 2.77 Experimental Group 3 453.31 143.35 0.74％ 2.78 base4 454.03 143.54 base 2.77 Experimental Group 4 454.75 143.88 0.24％ 2.78 base5 453.08 143.69 base 2.79 Experimental Group 5 453.10 144.86 0.81％ 2.80

[0090] Figure 5 FIG. 1 is a flow chart of a method for preparing a light emitting diode provided by an embodiment of the present disclosure. Figure 5 As shown, the preparation method comprises:

[0091] S11: forming an epitaxial layer.

[0092] The epitaxial layer includes a first semiconductor layer, a multi-quantum well layer and a second semiconductor layer stacked in sequence.

[0093] S12: forming a groove on the surface of the epitaxial layer, wherein at least a portion of the surface of the groove is a rough surface.

[0094] The roughness of the rough surface is greater than the roughness of the surface of the epitaxial layer except the groove.

[0095] The light-emitting diode prepared by this preparation method sets at least part of the surface of the groove of the epitaxial layer as a rough surface, and the roughness of the rough surface is greater than the roughness of the surface outside the groove on the epitaxial layer. That is, the surface of the groove is made rougher. Because the light emitted from the epitaxial layer of the groove on the smooth surface is more easily reflected or totally reflected at the junction of the smooth surface and the air or other film layers. Compared with the groove on the smooth surface, the groove on the rough surface used in the embodiment of the present disclosure disrupts the movement path of the light when the light is emitted to the rough surface, thereby reducing the reflection of the light and allowing more light to escape, thereby improving the light extraction efficiency of the light-emitting diode and improving the brightness of the light-emitting diode.

[0096] The epitaxial layer formed in step S11 is located on the substrate.

[0097] 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.

[0098] As an example, in the embodiment 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 sheet substrate.

[0099] The sapphire substrate may be pre-treated, placed in a MOCVD (Metal-organic Chemical Vapor Deposition) reaction chamber, and baked for 12 to 18 minutes. As an example, in the embodiment of the present disclosure, the sapphire substrate is baked for 15 minutes.

[0100] Specifically, the baking temperature may be 1000° C. to 1200° C., and the pressure in the MOCVD reaction chamber during baking may be 100 mbar to 200 mbar.

[0101] Before step S11 , the method may include: sequentially forming an AlN buffer layer and a u-type GaN layer on the sapphire substrate by using MOCVD technology.

[0102] Growing an epitaxial layer on the substrate in step S12 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.

[0103] Exemplarily, the epitaxial layer includes an n-type GaN layer, a multi-quantum well layer, and an n-type GaN layer stacked in sequence.

[0104] Optionally, the thickness of the n-type GaN layer may be 0.5 μm to 3 μm.

[0105] The growth temperature of the n-type GaN layer may be 1000° C. to 1100° C., and the growth pressure of the n-type GaN layer may be 100 torr to 300 torr.

[0106] Optionally, the multi-quantum well layer includes alternately grown InGaN quantum well layers and GaN quantum barrier layers. Wherein, the multi-quantum well layer may include 3 to 8 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0107] When growing multi-quantum well layers, the pressure of the MOCVD reaction chamber is controlled at 200 torr. When growing InGaN quantum well layers, the temperature of the reaction chamber is 760°C to 780°C. When growing GaN quantum barrier layers, the temperature of the reaction chamber is 860°C to 890°C.

[0108] As an example, in the embodiment of the present disclosure, the multi-quantum well layer includes five periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0109] Optionally, the thickness of the multi-quantum well layer may be 150 nm to 200 nm.

[0110] Optionally, the p-type GaN layer may have a thickness of 0.5 μm to 3 μm.

[0111] When growing the p-type GaN layer, the growth pressure of the p-type GaN layer may be 200 Torr to 600 Torr, and the growth temperature of the p-type GaN layer may be 800° C. to 1000° C.

[0112] Step S12 may include the following steps:

[0113] First, grooves are formed by etching the surface of the epitaxial layer.

[0114] Then, the temperature of the reaction chamber is controlled to be 25° C. to 90° C., and the epitaxial layer is soaked in an alkaline solution for 1 min to 2 h to roughen the surface of the groove.

[0115] In the embodiment disclosed herein, the degree of coarsening of the rough surface of the groove is related to the etching time and temperature. In the early stage of etching, when the temperature is low, the side wall of the groove is coarsened to form dense and small first protrusions. As the etching time and temperature increase, larger second protrusions are formed on the side wall of the groove. This is because during the etching process, part of the second protrusions are dissolved, while the other part of the second protrusions are not dissolved and slowly invade the dissolved second protrusions, that is, the two protrusions merge into one to form a large second protrusion.

[0116] Optionally, the alkali solution is a KOH solution, and the concentration of the KOH solution is 20 wt % to 55 wt %.

[0117] It should be noted that the alkaline solution may also be a NaOH solution and a Ca(OH)2 solution, which is not limited in the embodiments of the present disclosure.

[0118] After step S12, the preparation method further comprises the following steps:

[0119] In the first step, a current blocking layer is formed on the surface of the second semiconductor layer.

[0120] Exemplarily, the current blocking layer may be a silicon oxide layer, and the thickness of the current blocking layer is 200 angstroms to 3000 angstroms.

[0121] In the second step, a transparent conductive layer is formed on the surface of the second semiconductor layer so that the transparent conductive layer covers the current blocking layer.

[0122] Exemplarily, the transparent conductive layer is an indium tin oxide layer or an indium zinc oxide layer.

[0123] Exemplarily, the thickness of the transparent conductive layer may be 200 angstroms to 5000 angstroms. For example, the thickness of the transparent conductive layer is 2000 angstroms.

[0124] In the third step, a passivation layer is formed on the surface of the second semiconductor layer away from the first semiconductor layer and in the groove.

[0125] Specifically, it may include: forming a passivation layer on the surface of the p-type GaN layer, the surface of the transparent conductive layer, and in the groove.

[0126] Exemplarily, the passivation layer may be a silicon oxide layer, and the thickness of the passivation layer may be 800 angstroms to 3000 angstroms.

[0127] In the fourth step, an electrode is formed on the passivation layer, so that the electrode is electrically connected to the transparent conductive layer through the through hole, and an electrode is formed in the groove, so that the electrode is electrically connected to the first semiconductor layer.

[0128] The electrode in the groove is an n-type electrode, and the electrode on the passivation layer is a p-type electrode.

[0129] Illustratively, the electrode may be a first Al layer, a first Ti layer, a second Al layer, a second Ti layer, and an Au layer stacked in sequence.

[0130] Finally, the sapphire substrate can be cut and scratched by invisible cutting, which can effectively reduce the loss of brightness. Then, the light-emitting diode is obtained by testing.

[0131] The above description is only an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in 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), the surface of the epitaxial layer (20) having a groove (30), at least part of the surface of the groove (30) being a rough surface (31), the roughness of the rough surface (31) being greater than the roughness of the surface of the epitaxial layer (20) other than the groove (30).

2. The light emitting diode according to claim 1, characterized in that: The side wall of the groove (30) is the rough surface (31), and in a direction from the opening of the groove (30) to the groove bottom of the groove (30), the rough surface (31) comprises a first inclined surface (311) and a second inclined surface (312) which are connected in sequence, and the roughness of the first inclined surface (311) is smaller than the roughness of the second inclined surface (312).

3. The light emitting diode according to claim 2, characterized in that: The surface of the first inclined surface (311) has a plurality of first protrusions (313) arranged at intervals, and the surface of the second inclined surface (312) has a plurality of second protrusions (314) arranged at intervals; The number of the first protrusions (313) distributed per unit area is greater than the number of the second protrusions (314) distributed per unit area, and the maximum width of the first protrusion (313) is smaller than the maximum width of the second protrusion (314).

4. The light emitting diode according to claim 2, characterized in that: The inclination angle of the first inclined surface (311) is greater than the inclination angle of the second inclined surface (312).

5. The light emitting diode according to claim 1, 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, the groove (30) being located on a surface of the second semiconductor layer (23) away from the first semiconductor layer (21), and the groove (30) at least exposes the multi-quantum well layer (22); The rough surface (31) includes at least the side wall of the multi-quantum well layer (22) exposed by the groove (30).

6. The light emitting diode according to any one of claims 1 to 5, characterized in that: The light-emitting diode further comprises a passivation layer (40), wherein the passivation layer (40) is located on the surface of the epitaxial layer (20) and in the groove (30), and the surface roughness of the passivation layer (40) in the groove (30) is greater than the surface roughness of the passivation layer (40) outside the groove (30).

7. The light emitting diode according to any one of claims 1 to 5, characterized in that: The groove (30) includes at least one of an isolation groove (81) and an electrode groove (82).

8. A method for preparing a light emitting diode, characterized in that: The preparation method comprises: forming an epitaxial layer; A groove is formed on the surface of the epitaxial layer, at least a part of the surface of the groove is a rough surface, and the roughness of the rough surface is greater than the roughness of the surface of the epitaxial layer except the groove.

9. The preparation method according to claim 8, characterized in that: Forming a groove on the surface of the epitaxial layer includes: Etching a groove on the surface of the epitaxial layer; The temperature of the reaction chamber is controlled to be 25° C. to 90° C., and the epitaxial layer is soaked in an alkaline solution for 1 min to 2 h to roughen the surface of the groove.

10. The preparation method according to claim 9, characterized in that: The alkali solution is a KOH solution, and the concentration of the KOH solution is 20wt% to 55wt%.

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