CN115458652A - High-brightness light-emitting diode and preparation method thereof - Google Patents

High-brightness light-emitting diode and preparation method thereof Download PDF

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Publication number
CN115458652A
CN115458652A CN202210975513.9A CN202210975513A CN115458652A CN 115458652 A CN115458652 A CN 115458652A CN 202210975513 A CN202210975513 A CN 202210975513A CN 115458652 A CN115458652 A CN 115458652A
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layer
barrier layer
substrate
electrode
light
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Inventor
刘小星
尹灵峰
高艳龙
陈沛然
马国强
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HC Semitek Zhejiang Co Ltd
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HC Semitek Zhejiang Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/10—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a light reflecting structure, e.g. semiconductor Bragg reflector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005—Processes
    • H01L33/0062—Processes for devices with an active region comprising only III-V compounds
    • H01L33/0066—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound
    • H01L33/007—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound comprising nitride compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/44—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the coatings, e.g. passivation layer or anti-reflective coating
    • H01L33/46—Reflective coating, e.g. dielectric Bragg reflector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0025—Processes relating to coatings

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  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Led Devices (AREA)

Abstract

The present disclosure provides a high brightness light emitting diode and a method for manufacturing the same, the light emitting diode including: the device comprises a substrate, an epitaxial layer, a composite barrier layer, a first electrode and a second electrode; the epitaxial layer comprises a first semiconductor layer, a multi-quantum well layer and a second semiconductor layer which are sequentially laminated on the substrate, and the epitaxial layer is provided with a groove exposing the first semiconductor layer; the composite barrier layer is positioned on the surface of the second semiconductor layer and comprises a first barrier layer and a second barrier layer which are sequentially stacked, and the refractive index of the first barrier layer is higher than that of the second barrier layer; the first electrode is positioned in the groove and electrically connected with the first semiconductor layer, and the second electrode is positioned on the surface of the composite barrier layer and electrically connected with the second semiconductor layer. The light emitting diode can reduce the absorption of the electrode to light and improve the brightness and the luminous efficiency of the light emitting diode.

Description

High-brightness light-emitting diode and preparation method thereof
Technical Field
The disclosure relates to the technical field of photoelectron manufacturing, and in particular relates to a high-brightness light emitting diode and a preparation method thereof.
Background
The Light Emitting Diode (LED) is a new product with great influence in the photoelectronic industry, has the characteristics of small volume, long service life, rich and colorful colors, low energy consumption and the like, and is widely applied to the fields of illumination, display screens, signal lamps, backlight sources, toys and the like.
In the related art, the light emitting diode includes a substrate, an epitaxial layer, and a current blocking layer, which are sequentially stacked, and an electrode is usually disposed above the current blocking layer to block most of current from directly entering a region where the epitaxial layer is connected to the electrode, so that more current is spread to other regions of the epitaxial layer.
When the epitaxial layer emits light, the light easily passes through the epitaxial layer and the current blocking layer in sequence, irradiates the surface of the electrode and is absorbed by the electrode, so that the brightness and the light emitting efficiency of the light emitting diode are reduced.
Disclosure of Invention
The embodiment of the disclosure provides a high-brightness light emitting diode and a preparation method thereof, which can reduce the absorption of an electrode to light and improve the brightness and the light emitting efficiency of the light emitting diode. The technical scheme is as follows:
the disclosed embodiment provides a light emitting diode, which includes: the device comprises a substrate, an epitaxial layer, a composite barrier layer and a second electrode; the composite barrier layer is positioned on the surface of the epitaxial layer and comprises a first barrier layer and a second barrier layer which are sequentially laminated, and the refractive index of the first barrier layer is higher than that of the second barrier layer; the second electrode is located on the surface, far away from the substrate, of the composite barrier layer and is electrically connected with the epitaxial layer.
In one implementation of the embodiment of the present disclosure, the first blocking layer is an aluminum oxide layer, and the second blocking layer is a silicon oxide layer.
In another implementation of an embodiment of the disclosure, the ratio of the thickness of the second barrier layer to the thickness of the first barrier layer is 2:1 to 5:1.
In another implementation of the embodiments of the present disclosure, an orthographic projection of the second electrode on the substrate is within an orthographic projection of the composite barrier layer on the substrate.
In another implementation manner of the embodiment of the present disclosure, the epitaxial layer includes a first semiconductor layer, a multiple quantum well layer, and a second semiconductor layer sequentially stacked on the substrate, a surface of the second semiconductor layer, which is away from the substrate, has an accommodating groove, and the composite barrier layer is located in the accommodating groove; the light emitting diode further comprises a first electrode, the epitaxial layer is provided with a groove exposing the first semiconductor layer, and the first electrode is located in the groove and electrically connected with the first semiconductor layer.
In another implementation of the embodiment of the present disclosure, the first barrier layer is located on a bottom surface of the receiving groove and a sidewall of the receiving groove, and the first barrier layer separates the second semiconductor layer from the second barrier layer.
In another implementation manner of the embodiment of the present disclosure, an included angle between the side wall of the receiving groove and the bottom surface of the receiving groove is an obtuse angle.
In another implementation of the embodiment of the present disclosure, a surface of the composite barrier layer away from the substrate is flush with a surface of the second semiconductor layer away from the substrate.
In another implementation manner of the embodiment of the present disclosure, the light emitting diode further includes a transparent conductive layer, the transparent conductive layer is located on the surface of the second semiconductor layer and the composite barrier layer away from the substrate, and the second electrode is located on the surface of the transparent conductive layer away from the substrate.
The embodiment of the disclosure provides a preparation method of a light emitting diode, which comprises the following steps: providing a substrate; forming an epitaxial layer on the substrate; forming a composite barrier layer on the surface of the epitaxial layer, wherein the composite barrier layer comprises a first barrier layer and a second barrier layer which are sequentially stacked, and the refractive index of the first barrier layer is higher than that of the second barrier layer; and manufacturing a second electrode, wherein the second electrode is positioned on the surface of the composite barrier layer and is electrically connected with the epitaxial layer.
The beneficial effects brought by the technical scheme provided by the embodiment of the disclosure at least comprise:
the light emitting diode provided by the embodiment of the disclosure comprises a substrate and an epitaxial layer which are sequentially stacked. The surface of the epitaxial layer is provided with a composite barrier layer, the composite barrier layer comprises a first barrier layer and a second barrier layer which are sequentially stacked, and the refractive index of the first barrier layer is higher than that of the second barrier layer. And the second electrode sets up on compound barrier layer, and like this when epitaxial layer is luminous, the light that sends can advance and enter first barrier layer, and when the light entered into the second barrier layer from first barrier layer, because light is from high refracting index rete to low refracting index rete incidence, when the incident angle of light exceeded by the critical angle of first barrier layer and second barrier layer limited, will take place the total reflection to avoid the light that the epitaxial layer sent to incide the second barrier layer, and still avoid being located the second electrode absorption light above compound barrier layer. Therefore, a part of light rays emitted to the electrode are reflected towards the substrate through the composite barrier layer, the quantity of the light rays emitted from the light-emitting surface can be increased, the absorption of the electrode on the light rays is reduced, and the brightness and the luminous efficiency of the light-emitting diode are improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a light emitting diode provided in an embodiment of the present disclosure;
FIG. 2 is a diagram of a light path in a composite barrier layer according to an embodiment of the present disclosure;
fig. 3 is a flowchart of a method for manufacturing a light emitting diode according to an embodiment of the present disclosure.
The various symbols in the figures are illustrated as follows:
10. a substrate;
20. an epitaxial layer; 21. a first semiconductor layer; 22. a multiple quantum well layer; 23. a second semiconductor layer; 24. a groove; 25. accommodating grooves;
30. a composite barrier layer; 31. a first barrier layer; 32. a second barrier layer;
41. a first electrode; 42. a second electrode;
50. a transparent conductive layer; 51. a u-type GaN layer.
Detailed Description
To make the objects, technical solutions and advantages of the present disclosure more apparent, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," "third," and similar terms in the description and claims of the present disclosure are not intended to indicate any order, quantity, or importance, but rather are used to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprise" or "comprises", and the like, means that the element or item listed before "comprises" or "comprising" covers the element or item listed after "comprising" or "comprises" and its equivalents, and does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", "top", "bottom", and the like are used merely to indicate relative positional relationships, which may also change accordingly when the absolute position of the object being described changes.
Fig. 1 is a schematic structural diagram of a light emitting diode according to an embodiment of the present disclosure. As shown in fig. 1, the light emitting diode includes: substrate 10, epitaxial layer 20, composite barrier layer 30, and second electrode 42;
as shown in fig. 1, the composite barrier layer 30 is located on the surface of the epitaxial layer 20, and the composite barrier layer 30 includes a first barrier layer 31 and a second barrier layer 32 which are sequentially stacked, and the refractive index of the first barrier layer 31 is higher than that of the second barrier layer 32.
As shown in fig. 1, the second electrode 42 is located on the surface of the composite barrier layer 30 away from the substrate 10 and is electrically connected to the epitaxial layer 20.
The light emitting diode provided by the embodiment of the present disclosure includes a substrate 10 and an epitaxial layer 20 that are sequentially stacked. The surface of the epitaxial layer 20 is provided with a composite barrier layer 30, the composite barrier layer 30 comprises a first barrier layer 31 and a second barrier layer 32 which are sequentially laminated, and the refractive index of the first barrier layer 31 is higher than that of the second barrier layer 32. And, the second electrode 42 is on the composite barrier layer 30, so when the epitaxial layer 20 emits light, the emitted light will enter the first barrier layer 31 first, when the light enters the second barrier layer 32 from the first barrier layer 31, because the light is incident from the high refractive index film layer to the low refractive index film layer, when the incident angle of the light exceeds the critical angle defined by the first barrier layer 31 and the second barrier layer 32, total reflection will occur, thereby preventing the light emitted from the epitaxial layer 20 from entering the second barrier layer 32, and also preventing the light from being absorbed by the second electrode 42 located above the composite barrier layer 30. Thus, a part of the light emitted to the electrode is reflected towards the substrate 10 by the composite barrier layer, so that the quantity of the light emitted from the light-emitting surface can be increased, the absorption of the electrode on the light is reduced, and the brightness and the luminous efficiency of the light-emitting diode are improved.
Wherein the critical angle defined by the first barrier layer 31 and the second barrier layer 32 may be determined by the refractive index of the first barrier layer 31 and the refractive index of the second barrier layer 32. The formula for calculating the critical angle is: θ = arcsin (n) 2 /n 1 )。
Wherein θ is a critical angle, n 2 Is the refractive index, n, of the second barrier layer 32 1 Is the refractive index of the second barrier layer 32.
Optionally, the substrate 10 is a sapphire substrate 10. The sapphire substrate 10 has a relatively high light transmittance, i.e., the substrate 10 is a transparent substrate. And the sapphire material is hard, the chemical property is stable, and the light-emitting diode has good light-emitting effect and stability.
As shown in fig. 1, the epitaxial layer 20 includes a first semiconductor layer 21, a multiple quantum well layer 22, and a second semiconductor layer 23 sequentially stacked on the substrate 10, and a surface of the second semiconductor layer 23 has a groove 24 exposing the first semiconductor layer 21.
The light emitting diode further includes a first electrode 41, the first electrode 41 is located in the groove 24 and electrically connected to the first semiconductor layer 21, the composite barrier layer 30 is located on the second semiconductor layer 23, and the second electrode 42 is located on the surface of the composite barrier layer 30 and connected to the second semiconductor layer 23.
In the embodiment of the present disclosure, 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.
Illustratively, the first semiconductor layer 21 is an n-type layer and the second semiconductor layer 23 is a p-type layer.
Optionally, the first semiconductor layer 21 is a silicon-doped n-type GaN layer. The thickness of the n-type GaN layer may be 0.5 μm to 3 μm.
Alternatively, the multiple quantum well layer 22 includes InGaN quantum well layers and GaN quantum barrier layers that are alternately grown. Wherein, the multiple quantum well layer 22 may include InGaN quantum well layers and GaN quantum barrier layers alternately stacked for 3 to 8 periods.
As an example, in the present disclosure embodiment, the multiple quantum well layer 22 includes 5 periods of InGaN quantum well layers and GaN quantum barrier layers that are alternately stacked.
Alternatively, the thickness of the multiple quantum well layer 22 may be 150nm to 200nm.
Optionally, the second semiconductor layer 23 is a p-type GaN layer doped with magnesium. The thickness of the p-type GaN layer may be 0.5 μm to 3 μm.
In the embodiment of the present disclosure, the first barrier layer 31 is an aluminum oxide layer, and the second barrier layer 32 is a silicon oxide layer.
Wherein the refractive index of alumina is 1.76, and the refractive index of silica is 1.5. The calculation formula based on the aforementioned critical angle can be calculated, and the critical angle is 60 °.
Since the refractive index of the alumina layer is higher than that of the silicon oxide layer, when light enters the silicon oxide layer from the alumina layer, if the incident angle of the light exceeds 60 °, the light is totally reflected at the interface between the alumina layer and the silicon oxide layer. Thus, the light rays with the incident angle exceeding 60 degrees are all reflected to the light-emitting surface where the substrate 10 is located; and the light is prevented from being incident to the second electrode and being absorbed by the second electrode, so that the quantity of the light emitted from the light-emitting surface is increased, the absorption of the electrode on the light is reduced, and the brightness and the luminous efficiency of the light-emitting diode are improved.
Optionally, the ratio of the thickness of the second barrier layer to the thickness of the first barrier layer is 2:1 to 5:1.
Illustratively, the first barrier layer is an aluminum oxide layer and the second barrier layer is a silicon oxide layer.
The silicon oxide layer is a film layer for blocking current in the composite barrier layer 30, and thus, the thickness of the silicon oxide layer is set to be greater than that of the aluminum oxide layer, which can ensure the current blocking effect of the composite barrier layer 30.
Illustratively, the ratio of the thickness of the silicon oxide layer to the thickness of the aluminum oxide layer is 4:1.
Optionally, the orthographic projection of the second electrode 42 on the substrate 10 is within the orthographic projection of the composite barrier 30 on the substrate 10.
By setting the orthographic projection of the composite barrier layer 30 to be larger than that of the second electrode, the composite barrier layer 30 can completely shield the second electrode, and the light emitted from the epitaxial layer 20 is totally reflected at the composite barrier layer 30 at a certain incident angle. Therefore, the light can be prevented from directly entering the second electrode and being absorbed, the absorption amount of the light can be effectively reduced, and the brightness and the luminous efficiency of the light-emitting diode are improved.
Alternatively, as shown in fig. 1, the surface of the second semiconductor layer 23 away from the substrate 10 has a receiving groove 25, and the composite barrier layer 30 is located in the receiving groove 25.
As shown in fig. 1, the surface of the composite barrier layer 30 away from the substrate 10 is flush with the surface of the second semiconductor layer 23 away from the substrate 10.
By arranging the composite barrier layer 30 in the accommodating groove 25 and controlling the surface of the composite barrier layer 30 to be flush with the surface of the epitaxial layer 20, the composite barrier layer 30 is prevented from protruding from the surface of the epitaxial layer 20. This allows the film or the second electrode formed on the surface of the composite barrier layer 30 to be in more even contact with the epitaxial layer 20 and the composite barrier layer 30, thereby preventing the film or the second electrode formed on the surface of the composite barrier layer 30 from being broken.
Alternatively, as shown in fig. 1, the first barrier layer 31 is located on the bottom surface of the receiving groove 25 and the sidewall of the receiving groove 25, and the first barrier layer 31 separates the second semiconductor layer 23 and the second barrier layer 32.
In the embodiment of the present disclosure, the first blocking layer 31 is disposed on the bottom surface of the accommodating groove 25 and the side wall of the accommodating groove 25, that is, the first blocking layer 31 covers the inner wall surface of the accommodating groove 25. The second barrier layer 32 and the second semiconductor layer 23 are completely separated by the first barrier layer 31, so that light rays emitted to the composite barrier layer 30 from all positions of the epitaxial layer 20 can be reflected at the interface of the first barrier layer 31 and the second barrier layer 32, the amount of the light rays emitted to the second electrode is reduced, and the brightness of the light emitting diode is improved.
Alternatively, as shown in fig. 1, the side wall of the receiving groove 25 is an inclined surface, and an included angle between the side wall of the receiving groove 25 and the bottom surface of the receiving groove 25 is an obtuse angle.
Illustratively, as shown in fig. 1, an included angle between the side wall of the receiving groove 25 and the bottom surface of the receiving groove 25 is 120 °.
Fig. 2 is a diagram of the light path of light in the composite barrier layer 30 according to an embodiment of the disclosure. As indicated by X in fig. 2, when the incident angle of the light ray exceeds the critical angle, the light ray may be totally reflected at the interface between the first barrier layer 31 and the second barrier layer 32.
When the incident angle of the light is smaller than the critical angle, the light will enter the second blocking layer 32 through the first blocking layer 31, and the light path is as shown by Y in fig. 2, and the light will expand toward the sidewall of the accommodating groove 25 after entering the second blocking layer 32.
As shown in fig. 2, when light is incident on the interface between the second blocking layer 32 and the first blocking layer 31 again, since the light is incident from the low refractive index film to the high refractive index film, the light is refracted, and the refraction angle is smaller than the incident angle, so that the light is deflected toward the normal direction, and the light is emitted toward the substrate 10 again, and therefore, the amount of the light emitted from the light emitting surface can be increased, and the brightness and the light emitting efficiency of the led can be improved.
Alternatively, the depth of the receiving groove 25 is 2000 to 3000 angstroms. Wherein the ratio of the thickness of the silicon oxide layer to the thickness of the aluminum oxide layer is 2:1 to 5:1.
Illustratively, the depth of the receiving groove 25 is 2500 angstroms, and the ratio of the thickness of the silicon oxide layer to the thickness of the aluminum oxide layer is 4:1. Accordingly, the thickness of the silicon oxide layer may be 2000 angstroms and the thickness of the aluminum oxide layer may be 500 angstroms.
In the embodiment of the present disclosure, as shown in fig. 1, the light emitting diode further includes a transparent conductive layer 50, the transparent conductive layer 50 is located on the surface of the second semiconductor layer 23 and the surface of the composite barrier layer 30 away from the substrate 10, and the second electrode 42 is located on the surface of the transparent conductive layer 50.
Optionally, the transparent conductive layer 50 is an Indium Tin Oxide (ITO) layer. The indium tin oxide layer has good transmissivity and low resistivity, and more light can be transmitted out of the transparent conducting layer 50 by adopting the indium tin oxide layer as the transparent conducting layer 50, so that the effect is ensured; meanwhile, due to low resistivity, the method is convenient for carrier conduction and improves the injection efficiency.
Optionally, the transparent conductive layer 50 is an Indium Zinc Oxide (IZO) layer. The indium zinc oxide layer has good transmissivity and low resistivity, and more light can be transmitted out of the transparent conducting layer 50 by adopting the indium zinc oxide layer as the transparent conducting layer 50, so that the effect is ensured; meanwhile, due to low resistivity, the method is convenient for carrier conduction and improves the injection efficiency.
Illustratively, the thickness of the transparent conductive layer 50 may be 3000 to 6000 angstroms. For example, the transparent conductive layer 50 has a thickness of 4000 angstroms.
Optionally, as shown in fig. 1, the light emitting diode further includes a u-type GaN layer 51, the u-type GaN layer 51 being located between the submount and the epitaxial layer.
Fig. 3 is a flowchart of a method for manufacturing a light emitting diode according to an embodiment of the present disclosure. As shown in fig. 3, the preparation method comprises:
s11: a substrate 10 is provided.
S12: an epitaxial layer 20 is formed on the substrate 10.
Wherein the epitaxial layer 20 includes a first semiconductor layer 21, a multiple quantum well layer 22, and a second semiconductor layer 23 sequentially stacked on the substrate 10, and the epitaxial layer 20 has a groove 24 exposing the first semiconductor layer 21.
S13: a composite barrier layer 30 is formed on the surface of epitaxial layer 20.
The composite barrier layer 30 is located on the surface of the second semiconductor layer 23, the composite barrier layer 30 includes a first barrier layer 31 and a second barrier layer 32 which are sequentially stacked, and the refractive index of the first barrier layer 31 is higher than that of the second barrier layer 32.
S14: and manufacturing a second electrode.
In the embodiment of the present disclosure, the light emitting diode further includes a first electrode 41, the first electrode 41 is located in the groove 24 and electrically connected to the first semiconductor layer 21, and the second electrode 42 is located on the surface of the composite barrier layer 30 and electrically connected to the second semiconductor layer 23.
The light emitting diode prepared by the method includes a substrate 10, a first semiconductor layer 21, a multiple quantum well layer 22, and a second semiconductor layer 23, which are sequentially stacked. The second semiconductor layer 23 is provided with a composite barrier layer 30, the composite barrier layer 30 includes a first barrier layer 31 and a second barrier layer 32 which are sequentially stacked, and a refractive index of the first barrier layer 31 is higher than a refractive index of the second barrier layer 32. And, the second electrode 42 is disposed on the composite barrier layer 30, so that when the epitaxial layer 20 emits light, the emitted light enters the first barrier layer 31 first, and when the light enters the second barrier layer 32 from the first barrier layer 31, since the light is incident from the high refractive index film layer to the low refractive index film layer, when the incident angle of the light exceeds the critical angle defined by the first barrier layer 31 and the second barrier layer 32, total reflection occurs, thereby preventing the light emitted from the epitaxial layer 20 from entering the second barrier layer 32, and also preventing the light from being absorbed by the second electrode located above the composite barrier layer 30. Thus, a part of the light emitted to the electrode is reflected towards the substrate 10 through the composite barrier layer, so that the quantity of the light emitted from the light-emitting surface can be increased, the absorption of the electrode on the light is reduced, and the brightness and the luminous efficiency of the light-emitting diode are improved.
In step S11, the substrate 10 is a sapphire substrate 10, a silicon substrate 10, or a silicon carbide substrate 10. The substrate 10 may be a flat sheet substrate 10 or may be a patterned substrate 10.
As an example, in the embodiments of the present disclosure, the substrate 10 is a sapphire substrate 10. The sapphire substrate 10 is a common substrate 10, and has mature technology and low cost. Specifically, the patterned sapphire substrate 10 or the sapphire flat sheet substrate 10 may be used.
The sapphire substrate 10 may be pretreated, the sapphire substrate 10 is placed in an MOCVD (Metal-organic Chemical Vapor Deposition) reaction chamber, and the sapphire substrate 10 is baked for 12 to 18 minutes. As an example, in the embodiment of the present disclosure, the sapphire substrate 10 is subjected to the baking process for 15 minutes.
Specifically, the baking temperature may be 1000 ℃ to 1200 ℃, and the pressure in the MOCVD reaction chamber during baking may be 100mbar to 200mbar.
Growing the epitaxial layer 20 on the substrate 10 in step S12 may include: the first semiconductor layer 21, the multiple quantum well layer 22, and the second semiconductor layer 23 are sequentially formed on the sapphire substrate 10 by the MOCVD technique.
The first semiconductor layer 21 is an n-type layer, and the second semiconductor layer 23 is a p-type layer.
Optionally, the first semiconductor layer 21 is a silicon-doped n-type GaN layer. The thickness of the n-type GaN layer may be 0.5 μm to 3 μm.
The growth temperature of the n-type GaN layer may be 1000 ℃ to 1100 ℃, and the growth pressure of the n-type GaN layer may be 100torr to 300torr.
Alternatively, the multiple quantum well layer 22 includes InGaN quantum well layers and GaN quantum barrier layers that are alternately grown. Wherein, the multiple quantum well layer 22 may include InGaN quantum well layers and GaN quantum barrier layers alternately stacked for 3 to 8 periods.
When the multiple quantum well layer 22 was grown, the MOCVD reactor pressure was controlled at 200torr. When the InGaN quantum well layer is grown, the temperature of the reaction chamber is 760 ℃ to 780 ℃. When the GaN quantum barrier layer grows, the temperature of the reaction chamber is 860 ℃ to 890 ℃.
As an example, in the embodiment of the present disclosure, the multiple quantum well layer 22 includes 5 periods of InGaN quantum well layers and GaN quantum barrier layers that are alternately stacked.
Alternatively, the thickness of the multiple quantum well layer 22 may be 150nm to 200nm.
Optionally, the second semiconductor layer 23 is a p-type GaN layer doped with magnesium. The thickness of the p-type GaN layer may be 0.5 μm to 3 μm.
When the p-type GaN layer is grown, the growth pressure of the p-type GaN layer may be 200Torr to 600Torr and the growth temperature of the p-type GaN layer may be 800 ℃ to 1000 ℃.
After the epitaxial layer 20 is formed in step S12, the preparation method further includes: the second semiconductor layer 23 is etched to form a groove 24 exposing the first semiconductor layer 21.
Step S13 may include the following steps:
in a first step, a receiving groove 25 is etched in the second semiconductor layer 23.
Illustratively, the depth of the receiving groove 25 may be 2000 to 3000 angstroms.
In the second step, a composite barrier layer 30 is deposited in the receiving groove 25.
The composite barrier layer 30 includes a first barrier layer 31 and a second barrier layer 32, which are sequentially stacked. The first barrier layer 31 may be a high refractive index aluminum oxide layer, and the second barrier layer 32 may be a low refractive index silicon oxide layer. After the deposition of the two barrier layers, the surface of the silicon oxide layer is made flush with the surface of the second semiconductor layer 23.
After forming the composite barrier layer 30, the method of making may further include: a transparent conductive layer 50 is formed on the surface of the second semiconductor layer 23 by sputtering.
Illustratively, the transparent conductive layer 50 may be an ITO layer or an IZO layer.
Step S13 includes: the second electrode 42 is formed on the surface of the transparent conductive layer 50 away from the substrate 10, and the first electrode 41 is formed on the surface of the first semiconductor layer 21 in the recess 24.
The second electrode 42 on the second semiconductor layer 23 is mainly composed of au-be, and the first electrode 41 on the first semiconductor layer 21 is evaporated by using au-ge as a base material, and it is necessary to ensure the evaporation power when the au-ge alloy is evaporated, to avoid the evaporation time exceeding a second, to prevent the alloy components from deviating, and to perform annealing.
In the embodiment of the present disclosure, after the first electrode and the second electrode are fabricated, a protective layer may be further fabricated on the epitaxial layer 20.
Exemplarily, in the embodiments of the present disclosure, the protective layer may be a silicon oxide layer.
Finally, the sapphire substrate 10 can be subjected to invisible dicing scribing, and the invisible dicing scribing can well reduce the loss of brightness. Then, the light emitting diode is obtained through testing.
Although the present disclosure has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure.

Claims (10)

1. A light emitting diode, comprising: a substrate (10), an epitaxial layer (20), a composite barrier layer (30) and a second electrode (42);
the composite barrier layer (30) is positioned on the surface of the epitaxial layer (20), the composite barrier layer (30) comprises a first barrier layer (31) and a second barrier layer (32) which are sequentially laminated, and the refractive index of the first barrier layer (31) is higher than that of the second barrier layer (32);
the second electrode (42) is positioned on the surface of the composite barrier layer (30) far away from the substrate (10) and is electrically connected with the epitaxial layer (20).
2. The led of claim 1, wherein said first barrier layer (31) is an aluminum oxide layer and said second barrier layer (32) is a silicon oxide layer.
3. The led of claim 1, wherein the ratio of the thickness of the second barrier layer (32) to the thickness of the first barrier layer (31) is 2:1 to 5:1.
4. The led of claim 1, wherein an orthographic projection of the second electrode (42) on the substrate (10) is within an orthographic projection of the composite barrier layer (30) on the substrate (10).
5. The light-emitting diode according to any one of claims 1 to 4, wherein the epitaxial layer (20) comprises a first semiconductor layer (21), a MQW layer (22) and a second semiconductor layer (23) which are sequentially laminated on the substrate (10), a surface of the second semiconductor layer (23) away from the substrate (10) has a receiving groove (25), and the composite barrier layer (30) is located in the receiving groove (25);
the light-emitting diode further comprises a first electrode (41), the epitaxial layer (20) is provided with a groove (24) exposing the first semiconductor layer (21), and the first electrode (41) is located in the groove (24) and electrically connected with the first semiconductor layer (21).
6. The light-emitting diode according to claim 5, wherein the first barrier layer (31) is located on a bottom surface of the receiving groove (25) and a sidewall of the receiving groove (25), and the first barrier layer (31) separates the second semiconductor layer (23) and the second barrier layer (32).
7. The LED of claim 6, wherein the included angle between the side wall of the receiving groove (25) and the bottom surface of the receiving groove (25) is an obtuse angle.
8. The light-emitting diode according to claim 5, wherein the surface of the composite barrier layer (30) away from the substrate (10) is flush with the surface of the second semiconductor layer (23) away from the substrate (10).
9. The light-emitting diode according to claim 5, further comprising a transparent conductive layer (50), wherein the transparent conductive layer (50) is located on the surface of the second semiconductor layer (23) and the composite barrier layer (30) away from the substrate (10), and the second electrode (42) is located on the surface of the transparent conductive layer (50) away from the substrate (10).
10. A method for preparing a light emitting diode is characterized by comprising the following steps:
providing a substrate;
forming an epitaxial layer on the substrate;
forming a composite barrier layer on the surface of the epitaxial layer, wherein the composite barrier layer comprises a first barrier layer and a second barrier layer which are sequentially stacked, and the refractive index of the first barrier layer is higher than that of the second barrier layer;
and manufacturing a second electrode, wherein the second electrode is positioned on the surface of the composite barrier layer and is electrically connected with the epitaxial layer.
CN202210975513.9A 2022-08-15 2022-08-15 High-brightness light-emitting diode and preparation method thereof Pending CN115458652A (en)

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CN115458652A true CN115458652A (en) 2022-12-09

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