Light emitting diode with improved brightness and preparation method thereof

Abstract

The invention provides a light emitting diode with improved brightness and a preparation method thereof, and belongs to the technical field of photoelectron manufacturing. The preparation method of the light-emitting diode comprises the following steps: forming an epitaxial layer; carrying out plasma bombardment on the surface of the epitaxial layer by adopting an ion source; and evaporating a reflecting layer on the surface of the epitaxial layer to form an electrode. According to the embodiment of the invention, the resistance between the reflecting layer and the epitaxial layer can be reduced, and the brightness of the light-emitting diode is improved.

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 a very 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: an epitaxial layer and an electrode, and the electrode is located on the surface of the epitaxial layer. The electrode includes a contact layer and a reflective layer stacked on the epitaxial layer in sequence. Among them, the contact layer is a metal such as Cr, Ti and Ni that can form a good electrical contact with the epitaxial layer, and the reflective layer is a metal such as Al and Ag layer with good light-emitting performance.

[0004] Since metals such as Cr, Ti and Ni have strong absorption effects on light, they will affect the brightness of the flip-chip LED; if the reflective layer is directly in contact with the epitaxial layer, because the direct contact between Al or Ag metal and the epitaxial layer is a Schottky contact, it will cause the resistance of the LED to be very large, thus affecting the luminous effect of the LED. Summary of the invention

[0005] The embodiment of the present disclosure provides a light-emitting diode with improved brightness and a method for manufacturing the same, which can reduce the resistance between the reflective layer and the epitaxial layer and improve the brightness of the light-emitting diode. The technical solution is as follows:

[0006] On the one hand, an embodiment of the present disclosure provides a method for preparing a light-emitting diode, the method comprising: forming an epitaxial layer; using an ion source to perform plasma bombardment on the surface of the epitaxial layer; and evaporating a reflective layer on the surface of the epitaxial layer to form an electrode.

[0007] Optionally, using an ion source to perform plasma bombardment on the surface of the epitaxial layer includes: controlling the working power of the ion source to 500W to 700W, controlling the working pressure in the reaction chamber to be less than or equal to 0.01Pa, controlling the working time to 200s to 300s, and performing plasma bombardment on the surface of the epitaxial layer.

[0008] Optionally, the ion source is a microwave electron cyclotron resonance plasma source.

[0009] Optionally, evaporating a reflective layer on the surface of the epitaxial layer to form an electrode includes: evaporating a reflective layer on the surface of the epitaxial layer, the reflective layer including at least one of an Al layer and an Ag layer; evaporating a wrapping layer on the surface of the reflective layer, the wrapping layer including at least one of a Ni layer, a Pt layer, an Au layer, an Al layer and an AlCu layer; evaporating a protective layer on the surface of the wrapping layer, the protective layer including at least one of a Ni layer, a Pt layer and a Ti layer.

[0010] Optionally, evaporating a reflective layer on the surface of the epitaxial layer comprises: controlling the evaporation rate to be 4 angstroms / second to 6 angstroms / second, and evaporating an Al layer of 1500 angstroms to 2500 angstroms; evaporating a wrapping layer on the surface of the reflective layer comprises: controlling the evaporation rate to be 1 angstroms / second to 3 angstroms / second, and evaporating a Ti layer of 300 angstroms to 700 angstroms; controlling the evaporation rate to be 4 angstroms / second to 6 angstroms / second, and evaporating an Ni layer of 800 angstroms to 1200 angstroms; controlling the evaporation rate to be 4 angstroms / second to 6 angstroms / second, evaporating a Pt layer of 1500 to 2500 angstroms; controlling the evaporation rate to be 6 angstroms / second to 10 angstroms / second, evaporating a Au layer of 6000 to 10000 angstroms; evaporating a protective layer on the surface of the wrapping layer includes: controlling the evaporation rate to be 1 angstroms / second to 3 angstroms / second, evaporating a Pt layer of 1500 to 2500 angstroms; controlling the evaporation rate to be 1 angstroms / second to 3 angstroms / second, evaporating a Ti layer of 300 to 700 angstroms.

[0011] On the other hand, an embodiment of the present disclosure provides a light-emitting diode, which includes: an epitaxial layer and an electrode, wherein the electrode includes a reflective layer, the reflective layer is stacked on the surface of the epitaxial layer, and the reflective layer directly contacts the epitaxial layer.

[0012] Optionally, a contact resistance between the interface between the reflective layer and the surface of the epitaxial layer is less than or equal to 0.3Ω / □.

[0013] Optionally, the electrode further includes a wrapping layer and a protective layer, and the reflective layer, the wrapping layer and the protective layer are sequentially stacked on the surface of the epitaxial layer; the reflective layer includes at least one of an Al layer and an Ag layer, the wrapping layer includes at least one of a Ni layer, a Pt layer, an Au layer, an Al layer and an AlCu layer, and the protective layer includes at least one of a Ni layer, a Pt layer and a Ti layer.

[0014] Optionally, the reflective layer includes an Al layer, the thickness of the Al layer in the reflective layer is 1500 angstroms to 2500 angstroms; the wrapping layer includes a Ti layer, a Ni layer, a Pt layer and an Au layer stacked in sequence, the thickness of the Ti layer in the wrapping layer is 300 angstroms to 700 angstroms, the thickness of the Ni layer in the wrapping layer is 800 angstroms to 1200 angstroms, the thickness of the Pt layer in the wrapping layer is 1500 angstroms to 2500 angstroms, and the thickness of the Au layer in the wrapping layer is 6000 angstroms to 10000 angstroms; the protective layer includes a Pt layer and a Ti layer stacked in sequence, the thickness of the Pt layer in the protective layer is 1500 angstroms to 2500 angstroms, and the thickness of the Ti layer in the protective layer is 300 angstroms to 700 angstroms.

[0015] Optionally, the epitaxial layer includes a first semiconductor layer, a multi-quantum well layer, and a second semiconductor layer stacked in sequence, the surface of the second semiconductor layer has a groove exposing the first semiconductor layer; the electrode is at least located in the groove and is electrically connected to the first semiconductor layer, and the first semiconductor layer is Al x Ga (1-x) N material layer, wherein X is greater than or equal to 0 and less than or equal to 1.

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

[0017] In the preparation method of the light-emitting diode provided by the embodiment of the present disclosure, when evaporating the electrode reflective layer, an ion source is first used to perform plasma bombardment on the surface of the epitaxial layer, and the plasma is used to remove C or O impurities on the surface of the epitaxial layer. If the C or O impurities are not removed, the Al or Ag metal in the reflective layer will combine with C / O to form an interface state. The potential barrier of the interface state is high, and it is not easy for electrons to pass through the interface state to reach the epitaxial layer, resulting in a large contact resistance between the epitaxial layer and the reflective layer. Before evaporating the reflective layer, the surface of the epitaxial layer is cleaned by plasma to eliminate C or O impurities on the surface of the epitaxial layer, so that the Al or Ag metal in the reflective layer can better contact with the epitaxial layer to form an ohmic contact, thereby greatly reducing the contact resistance between the epitaxial layer and the reflective layer. In this way, metals such as Cr, Ti and Ni are not formed on the epitaxial layer as a contact layer to reduce the absorption of light by the electrode, and the Al or Ag metal in the reflective layer directly forms an ohmic contact with the epitaxial layer to reduce the contact resistance, thereby improving the luminous 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 flow chart of a method for preparing a light emitting diode provided by an embodiment of the present disclosure;

[0020] Figure 2 is a structural schematic diagram of a light emitting diode provided by an embodiment of the present disclosure;

[0021] Figure 3 It is a schematic diagram of the structure of an electrode provided in an embodiment of the present disclosure.

[0022] The descriptions of the marks in the figure are as follows:

[0023] 10. Substrate;

[0024] 20. epitaxial layer; 21. first semiconductor layer; 22. multi-quantum well layer; 23. second semiconductor layer; 24. groove;

[0025] 30. Electrode;

[0026] 31. Reflection layer; 32. Wrapping layer; 33. Protective layer;

[0027] 40. Transparent conductive layer; 41. Metal reflective layer; 42. Metal surrounding layer;

[0028] 51. a first insulating layer; 52. a second insulating layer;

[0029] 60. Soldering pad. DETAILED DESCRIPTION

[0030] 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.

[0031] 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.

[0032] Figure 1 FIG. 1 is a flow chart of a method for preparing a light emitting diode provided by an embodiment of the present disclosure. Figure 1 As shown, the preparation method comprises:

[0033] Step S11: forming an epitaxial layer.

[0034] Step S12: using an ion source to perform plasma bombardment on the surface of the epitaxial layer.

[0035] Among them, the C or O impurities on the surface of the epitaxial layer can be removed by bombarding the epitaxial layer with plasma.

[0036] Step S13: evaporating a reflective layer on the surface of the epitaxial layer to form an electrode.

[0037] In the preparation method of the light-emitting diode provided by the embodiment of the present disclosure, when evaporating the electrode reflective layer, an ion source is first used to perform plasma bombardment on the surface of the epitaxial layer, and the plasma is used to remove C or O impurities on the surface of the epitaxial layer. If the C or O impurities are not removed, the Al or Ag metal in the reflective layer will combine with C / O to form an interface state. The potential barrier of the interface state is high, and it is not easy for electrons to pass through the interface state to reach the epitaxial layer, resulting in a large contact resistance between the epitaxial layer and the reflective layer. Before evaporating the reflective layer, the surface of the epitaxial layer is cleaned by plasma to eliminate C or O impurities on the surface of the epitaxial layer, so that the Al or Ag metal in the reflective layer can better contact with the epitaxial layer to form an ohmic contact, thereby greatly reducing the contact resistance between the epitaxial layer and the reflective layer. In this way, metals such as Cr, Ti and Ni are not formed on the epitaxial layer as a contact layer to reduce the absorption of light by the electrode, and the Al or Ag metal in the reflective layer directly forms an ohmic contact with the epitaxial layer to reduce the contact resistance, thereby improving the luminous brightness of the light-emitting diode.

[0038] The process of preparing the epitaxial layer in step S11 may include the following steps:

[0039] First, a substrate is provided.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] Growing an epitaxial layer on the substrate may include: sequentially forming a first semiconductor layer, a multi-quantum well layer, and a second semiconductor layer on the sapphire substrate by using MOCVD technology.

[0045] The first semiconductor layer is an n-type layer, and the second semiconductor layer is a p-type layer.

[0046] Optionally, the first semiconductor layer 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Optionally, the thickness of the multi-quantum well layer may be 150 nm to 200 nm.

[0052] Optionally, the second semiconductor layer is a magnesium-doped p-type GaN layer. The thickness of the p-type GaN layer may be 0.5 μm to 3 μm.

[0053] 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.

[0054] Then, the second semiconductor layer is etched to form a groove exposing the first semiconductor layer.

[0055] Next, a transparent conductive layer is formed on the surface of the second semiconductor layer.

[0056] Exemplarily, the transparent conductive layer is an indium tin oxide layer or an indium zinc oxide layer.

[0057] Exemplarily, the thickness of the transparent conductive layer is 100 angstroms to 300 angstroms. For example, the thickness of the transparent conductive layer is 250 angstroms.

[0058] Then, a metal light reflecting layer is formed on the surface of the transparent conductive layer away from the first semiconductor layer.

[0059] Optionally, the metal reflective layer includes an Ag layer, a Ni layer and a TiW layer stacked in sequence.

[0060] Exemplarily, the thickness of the Ag layer is 1400 angstroms to 1700 angstroms. For example, the thickness of the Ag layer is 1500 angstroms.

[0061] Exemplarily, the thickness of the Ni layer is 100 angstroms to 300 angstroms. For example, the thickness of the Ni layer is 200 angstroms.

[0062] Exemplarily, the thickness of the TiW layer is 700 angstroms to 1000 angstroms. For example, the thickness of the TiW layer is 800 angstroms.

[0063] Next, a metal surrounding layer is formed on the surface of the transparent conductive layer away from the first semiconductor layer, so that the metal surrounding layer covers the metal reflective layer.

[0064] Optionally, the metal surrounding layer includes a Cr layer, an Al layer, a Ti layer, an Al layer, a Ti layer, an Al layer, a Cr layer, a Pt layer and a Ti layer stacked in sequence, and the thickness of each metal layer is 30 angstroms, 2000 angstroms, 1000 angstroms, 2000 angstroms, 1000 angstroms, 2000 angstroms, 500 angstroms, 2000 angstroms and 500 angstroms respectively.

[0065] Then, a first insulating layer is formed on the surface of the second semiconductor layer, on the surface of the transparent conductive layer, and in the groove, so that the first insulating layer covers the transparent conductive layer and the metal surrounding layer.

[0066] Next, a through hole exposing the metal surrounding layer and a through hole exposing the bottom of the groove are formed on the surface of the first insulating layer by photolithography.

[0067] Exemplarily, the first insulating layer may be a silicon oxide layer.

[0068] Exemplarily, the thickness of the first insulating layer is 4000 angstroms to 6000 angstroms.

[0069] The process of plasma bombarding the epitaxial layer in step S12 may include: controlling the working power of the ion source to 500W to 700W, controlling the working pressure in the reaction chamber to be less than or equal to 0.01Pa, controlling the working time to 200s to 300s, and plasma bombarding the surface of the epitaxial layer.

[0070] When the epitaxial layer is bombarded with plasma by an ion source, controlling the working power of the ion source within the above range can provide a more stable plasma to clean the surface of the epitaxial layer. At the same time, controlling the working time within the above range can ensure that the plasma cleans the surface of the epitaxial layer for a sufficient time, thereby ensuring that the impurities on the surface of the epitaxial layer are completely removed. In addition, when the epitaxial layer is bombarded with an ion source, a sufficiently low working pressure can be used, which can reduce the difficulty of plasma treatment.

[0071] Exemplarily, the working power of the ion source is controlled to be 600 W, the working pressure in the reaction chamber is controlled to be 0.01 Pa, the working time is controlled to be 240 s, and plasma bombardment is performed on the surface of the epitaxial layer.

[0072] Optionally, the ion source is a microwave electron cyclotron resonance plasma source.

[0073] The microwave electron cyclotron resonance plasma source accelerates electrons to collide with neutral atoms through microwave electric fields to generate plasma. The microwave electron cyclotron resonance plasma source can limit the movement of plasma with a magnetic field, and will not interact with the cavity wall of the reaction chamber, which can greatly reduce the loss of the ion source, and the output ion current intensity can meet the performance requirements. The impurities produced are lower, and it can operate in a very low pressure environment. At the same time, the size of the microwave electron cyclotron resonance plasma source is very small and can be installed in the evaporation machine, thus saving the space occupied by the equipment.

[0074] The forming of the electrode in step S13 may include the following steps:

[0075] First, a reflective layer is evaporated on the surface of the epitaxial layer, and the reflective layer includes at least one of an Al layer and an Ag layer.

[0076] Exemplarily, the reflective layer may include an Al layer.

[0077] When preparing the reflective layer, the evaporation rate can be controlled to be 4 angstroms / second to 6 angstroms / second, and an Al layer of 1500 angstroms to 2500 angstroms can be evaporated.

[0078] Exemplarily, when preparing the reflective layer, the evaporation rate is controlled to be 5 angstroms / second, and a 2000 angstrom Al layer is evaporated.

[0079] Then, a coating layer is evaporated on the surface of the reflective layer, wherein the coating layer includes at least one of a Ni layer, a Pt layer, an Au layer, an Al layer and an AlCu layer.

[0080] Illustratively, the wrapping layer includes a Ti layer, a Ni layer, a Pt layer, and an Au layer stacked in sequence.

[0081] The wrapping layer includes a plurality of stacked metal layers, so that the wrapping layer can reduce the resistance of the electrode with a thicker metal layer and at the same time, can play a role in protecting the reflective layer.

[0082] When preparing the encapsulation layer, the evaporation rate can be controlled to be 1 angstrom / second to 3 angstroms / second, and a Ti layer of 300 to 700 angstroms can be evaporated. The evaporation rate can be controlled to be 4 angstroms / second to 6 angstroms / second, and a Ni layer of 800 to 1200 angstroms can be evaporated. The evaporation rate can be controlled to be 4 angstroms / second to 6 angstroms / second, and a Pt layer of 1500 to 2500 angstroms can be evaporated. The evaporation rate can be controlled to be 6 angstroms / second to 10 angstroms / second, and a Au layer of 6000 to 10000 angstroms can be evaporated.

[0083] For example, when preparing the encapsulation layer, the evaporation rate is controlled to be 2 angstroms / second, and a 500 angstrom Ti layer is evaporated.

[0084] Exemplarily, when preparing the encapsulation layer, the evaporation rate is controlled to be 5 angstroms / second, and a Ni layer of 1000 angstroms is evaporated.

[0085] Exemplarily, when preparing the encapsulating layer, the evaporation rate is controlled to be 5 angstroms / second, and a 2000 angstrom Pt layer is evaporated.

[0086] Exemplarily, when preparing the encapsulation layer, the evaporation rate is controlled to be 8 angstroms / second, and an Au layer of 8000 angstroms is evaporated.

[0087] Next, a protective layer is evaporated on the surface of the coating layer, wherein the protective layer includes at least one of a Ni layer, a Pt layer and a Ti layer.

[0088] Illustratively, the protective layer includes a Pt layer and a Ti layer stacked in sequence.

[0089] The protective layer is used to protect the wrapping layer to prevent the wrapping layer from being corroded, etched or oxidized.

[0090] When preparing the protective layer, the evaporation rate can be controlled to be 1 angstrom / second to 3 angstroms / second, and a Pt layer of 1500 to 2500 angstroms can be evaporated; the evaporation rate can be controlled to be 1 angstrom / second to 3 angstroms / second, and a Ti layer of 300 to 700 angstroms can be evaporated.

[0091] Illustratively, when preparing the protective layer, the evaporation rate is controlled to be 2 angstroms / second, and a 2000 angstrom Pt layer is evaporated.

[0092] Exemplarily, when preparing the protective layer, the evaporation rate is controlled to be 2 angstroms / second, and a 500 angstrom Ti layer is evaporated.

[0093] Optionally, the prepared electrode includes two parts insulated from each other, one part of the electrode is located in the groove and connected to the first semiconductor layer, and the other part of the electrode is located on the surface of the first insulating layer and electrically connected to the metal surrounding layer through a through hole.

[0094] After step S13, the preparation method further comprises the following steps:

[0095] First, a second insulating layer is formed on a surface of the first insulating layer so that the second insulating layer covers the electrode.

[0096] Exemplarily, the second insulating layer is a DBR (Distributed Bragg Reflector) layer, and the DBR layer includes a plurality of silicon oxide layers and a plurality of titanium oxide layers, and the thickness of the DBR layer is 3 μm to 4 μm.

[0097] Then, the second insulating layer is etched to form a through hole exposing the electrode on the surface of the second insulating layer.

[0098] Next, a pad is formed on a surface of the second insulating layer away from the epitaxial layer, and the pad is electrically connected to the electrode through the through hole.

[0099] Optionally, the pad layer includes a first Ti layer, an Al layer, a second Ti layer, a Pt layer, a Ni layer and an Au layer stacked in sequence.

[0100] Exemplarily, the thickness of the first Ti layer is 20 angstroms to 100 angstroms. For example, the thickness of the first Ti layer is 50 angstroms.

[0101] Exemplarily, the thickness of the Al layer is 10000 angstroms to 20000 angstroms. For example, the thickness of the Al layer is 15000 angstroms.

[0102] Exemplarily, the thickness of the second Ti layer is 500 angstroms to 1500 angstroms. For example, the thickness of the second Ti layer is 1000 angstroms.

[0103] Exemplarily, the thickness of the Pt layer is 500 angstroms to 1500 angstroms. For example, the thickness of the Pt layer is 1000 angstroms.

[0104] Exemplarily, the thickness of the Ni layer is 60,000 angstroms to 80,000 angstroms. For example, the thickness of the Ni layer is 70,000 angstroms.

[0105] Exemplarily, the thickness of the Au layer is 1500 angstroms to 2500 angstroms. For example, the thickness of the Au layer is 2000 angstroms.

[0106] Figure 2 Schematic diagram of the structure of a light emitting diode provided by an embodiment of the present disclosure. Figure 2 As shown, the light-emitting diode includes: an epitaxial layer 20 and an electrode 30, the electrode 30 includes a reflective layer 31, the reflective layer 31 is stacked on the surface of the epitaxial layer 20, and the reflective layer 31 directly contacts the epitaxial layer 20, and the surface of the epitaxial layer 20 stacked with the reflective layer 31 is a surface bombarded by plasma.

[0107] The surface of the epitaxial layer 20 of the light-emitting diode for laminating the reflective layer 31 is a surface that has been bombarded by plasma. Thus, before preparing the electrode 30, the surface of the epitaxial layer 20 is first bombarded by plasma using an ion source, and the C or O impurities on the surface of the epitaxial layer 20 are removed by plasma. If the C or O impurities are not removed, the Al or Ag metal in the reflective layer 31 will bond with C / O to form an interface state, and the potential barrier of the interface state is high, and it is not easy for electrons to pass through the interface state to reach the epitaxial layer 20, resulting in a large contact resistance between the epitaxial layer 20 and the reflective layer 31. Before evaporating the reflective layer 31, the surface of the epitaxial layer 20 is cleaned by plasma to eliminate the C or O impurities on the surface of the epitaxial layer 20, so that the Al or Ag metal in the reflective layer 31 can be better in contact with the epitaxial layer 20, forming an ohmic contact, thereby greatly reducing the contact resistance between the epitaxial layer 20 and the reflective layer 31. In this way, no metal such as Cr, Ti and Ni is formed on the epitaxial layer 20 as a contact layer to reduce the absorption of light by the electrode 30, and the Al or Ag metal of the reflective layer 31 directly forms an ohmic contact with the epitaxial layer 20 to reduce the contact resistance, thereby improving the brightness of the light-emitting diode.

[0108] Alternatively, if Figure 2 As shown, the light emitting diode further includes a substrate 10 , and an epitaxial layer 20 is located on the surface of the substrate 10 .

[0109] Exemplarily, the substrate 10 is a sapphire substrate 10. The sapphire substrate 10 has a relatively high light transmittance, that is, the substrate 10 is a transparent substrate 10. 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.

[0110] In the disclosed embodiment, the epitaxial layer 20 includes a first semiconductor layer 21 , a multi-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 .

[0111] 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.

[0112] Exemplarily, the first semiconductor layer 21 is an n-type layer, and the second semiconductor layer 23 is a p-type layer.

[0113] In the implementation of the present disclosure, the first semiconductor layer 21 is Al x Ga (1-x) N material layer, wherein X is greater than or equal to 0 and less than or equal to 1.

[0114] Exemplarily, when X is 0, the first semiconductor layer 21 is a GaN layer. For example, 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.

[0115] Optionally, the multi-quantum well layer 22 includes alternately grown InGaN quantum well layers and GaN quantum barrier layers. The multi-quantum well layer 22 may include 3 to 8 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0116] 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.

[0117] Optionally, the thickness of the multi-quantum well layer 22 may be 150 nm to 200 nm.

[0118] 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.

[0119] Optionally, the second semiconductor layer 23 has a groove 24 exposing the first semiconductor layer 21 .

[0120] Alternatively, if Figure 2 As shown, the light emitting diode further includes: a transparent conductive layer 40 , a metal reflective layer 41 and a metal surrounding layer 42 .

[0121] like Figure 2 As shown, the transparent conductive layer 40 is located on the surface of the second semiconductor layer 23 , the metal reflective layer 41 is located on the surface of the transparent conductive layer 40 away from the epitaxial layer 20 , and the metal surrounding layer 42 is located on the surface of the transparent conductive layer 40 away from the epitaxial layer 20 and covers the metal reflective layer 41 .

[0122] Optionally, the transparent conductive layer 40 may be an indium tin oxide (ITO) layer or an indium zinc oxide (IZO) layer.

[0123] Exemplarily, the transparent conductive layer 40 is an indium tin oxide layer. The indium tin oxide layer has good transmittance and low resistivity. The indium tin oxide layer has low resistivity, facilitates carrier conduction, and improves injection efficiency.

[0124] Exemplarily, the transparent conductive layer 40 is an indium zinc oxide layer. The indium zinc oxide layer has good transmittance and low resistivity. The indium zinc oxide layer has low resistivity, facilitates carrier conduction, and improves injection efficiency.

[0125] Exemplarily, the thickness of the transparent conductive layer 40 is 100 angstroms to 300 angstroms. For example, the thickness of the transparent conductive layer 40 is 200 angstroms.

[0126] In the above implementation, by disposing the transparent conductive layer 40 between the metal reflective layer 41 and the epitaxial layer 20 , the current conduction efficiency between the metal reflective layer 41 and the epitaxial layer 20 can be improved.

[0127] The metal reflective layer 41 can be used to reflect the light emitted from the epitaxial layer 20 , so that more light can be emitted from the light emitting surface of the epitaxial layer 20 , thereby improving the light emitting intensity of the light emitting diode.

[0128] At the same time, the metal reflective layer 41 is also covered with a metal surrounding layer 42 to prevent the metal in the metal reflective layer 41 from migrating upward.

[0129] Optionally, the metal reflective layer 41 includes an Ag layer, a Ni layer and a TiW layer stacked in sequence.

[0130] Since Ag has a good reflective effect, providing an Ag layer in the reflective layer 31 can enhance the reflection of light by the reflective layer 31 and improve the light output brightness of the light output surface 21 of the light emitting diode.

[0131] The Ni layer has good corrosion resistance and wear resistance, and the TiW layer can be successfully deposited on other films as an adhesion layer without peeling or cracking. The alternating stacked Ni and TiW layers can act as a barrier layer to protect the silver mirror.

[0132] Exemplarily, the thickness of the Ag layer is 1400 angstroms to 1700 angstroms. For example, the thickness of the Ag layer is 1500 angstroms.

[0133] Exemplarily, the thickness of the Ni layer is 100 angstroms to 300 angstroms. For example, the thickness of the Ni layer is 200 angstroms.

[0134] Exemplarily, the thickness of the TiW layer is 700 angstroms to 1000 angstroms. For example, the thickness of the TiW layer is 800 angstroms.

[0135] Optionally, the metal surrounding layer 42 includes a Cr layer, an Al layer, a Ti layer, an Al layer, a Ti layer, an Al layer, a Cr layer, a Pt layer and a Ti layer stacked in sequence, and the thickness of each metal layer is 30 angstroms, 2000 angstroms, 1000 angstroms, 2000 angstroms, 1000 angstroms, 2000 angstroms, 500 angstroms, 2000 angstroms and 500 angstroms respectively.

[0136] Alternatively, if Figure 2 As shown, the light emitting diode further includes a first insulating layer 51 , which is located on the surface of the second semiconductor layer 23 , on the surface of the transparent conductive layer 40 , and in the groove 24 .

[0137] The surface of the first insulating layer 51 has a through hole exposing the metal surrounding layer 42 and a through hole exposing the bottom of the groove 24 .

[0138] Exemplarily, the first insulating layer 51 may be a silicon oxide layer.

[0139] Exemplarily, the thickness of the first insulating layer 51 is 4000 angstroms to 6000 angstroms.

[0140] Alternatively, if Figure 2 As shown, the electrode 30 is located on the surface of the first insulating layer 51 and is electrically connected to the metal surrounding layer 42 and the first semiconductor layer 21 in the groove 24 through through holes.

[0141] Optionally, the contact resistance between the interface of the reflective layer 31 and the surface of the epitaxial layer 20 is less than or equal to 0.3Ω / □.

[0142] In the embodiment of the present disclosure, the surface of the epitaxial layer 20 is cleaned by plasma before evaporating the reflective layer 31 to eliminate C or O impurities on the surface of the epitaxial layer 20, so that the Al or Ag metal in the reflective layer 31 can be in better contact with the epitaxial layer 20 to form an ohmic contact, thereby greatly reducing the contact resistance between the epitaxial layer 20 and the reflective layer 31.

[0143] Exemplarily, the contact resistance between the interface of the reflective layer 31 and the surface of the epitaxial layer 20 is 0.3Ω / □.

[0144] Figure 3 Schematic diagram of the structure of an electrode 30 provided in an embodiment of the present disclosure. Figure 3 As shown, the electrode 30 further includes a wrapping layer 32 and a protective layer 33 , and the reflective layer 31 , the wrapping layer 32 and the protective layer 33 are sequentially stacked on the surface of the epitaxial layer 20 .

[0145] The reflective layer 31 includes at least one of an Al layer and an Ag layer, the wrapping layer 32 includes at least one of a Ni layer, a Pt layer, an Au layer, an Al layer and an AlCu layer, and the protective layer 33 includes at least one of a Ni layer, a Pt layer and a Ti layer.

[0146] In the disclosed embodiment, the wrapping layer 32 includes a plurality of stacked metal layers, so that the wrapping layer 32 can reduce the resistance of the electrode 30 with a thicker metal layer, and at the same time, can play a role in protecting the reflective layer 31. The protective layer 33 is used to protect the wrapping layer 32 and prevent the wrapping layer 32 from being corroded, etched or oxidized.

[0147] Optionally, the reflective layer 31 includes an Al layer, and the thickness of the Al layer in the reflective layer 31 is 1500 angstroms to 2500 angstroms.

[0148] Exemplarily, the thickness of the Al layer in the reflective layer 31 is 2000 angstroms.

[0149] Optionally, the wrapping layer 32 includes a Ti layer, a Ni layer, a Pt layer and an Au layer stacked in sequence, the thickness of the Ti layer in the wrapping layer 32 is 300 angstroms to 700 angstroms, the thickness of the Ni layer in the wrapping layer 32 is 800 angstroms to 1200 angstroms, the thickness of the Pt layer in the wrapping layer 32 is 1500 angstroms to 2500 angstroms, and the thickness of the Au layer in the wrapping layer 32 is 6000 angstroms to 10000 angstroms.

[0150] Exemplarily, the thickness of the Ti layer in the encapsulation layer 32 is 500 angstroms.

[0151] Exemplarily, the thickness of the Ni layer in the encapsulation layer 32 is 1000 angstroms.

[0152] Exemplarily, the thickness of the Pt layer in the encapsulation layer 32 is 2000 angstroms.

[0153] Exemplarily, the thickness of the Au layer in the encapsulation layer 32 is 8000 angstroms.

[0154] Optionally, the protective layer 33 includes a Pt layer and a Ti layer stacked in sequence, the thickness of the Pt layer in the protective layer 33 is 1500 angstroms to 2500 angstroms, and the thickness of the Ti layer in the protective layer 33 is 300 angstroms to 700 angstroms.

[0155] Exemplarily, the thickness of the Pt layer in the protection layer 33 is 2000 angstroms.

[0156] By way of example, the thickness of the Ti layer in the protection layer 33 is 500 angstroms.

[0157] Alternatively, if Figure 1 As shown, the light emitting diode may further include a second insulating layer 52 and a pad 60, wherein the second insulating layer 52 is located on the surface of the first insulating layer 51 and covers the electrode 30. The second insulating layer 52 has a through hole exposing the electrode 30, and the pad 60 is located on the surface of the second insulating layer 52 away from the epitaxial layer 20, and the pad 60 is electrically connected to the electrode 30 through the through hole.

[0158] Optionally, the pad 60 includes at least one of a Ti layer, an Al layer, a Pt layer, a Ni layer, and an Au layer.

[0159] The above metal material has good heat dissipation performance. Therefore, the pad 60 made of the above material also has good heat dissipation performance, which can improve the heat dissipation effect of the light emitting diode.

[0160] Alternatively, the pad 60 includes a first Ti layer, an Al layer, a second Ti layer, a Pt layer, a Ni layer, and an Au layer stacked in sequence.

[0161] Exemplarily, the thickness of the first Ti layer is 20 angstroms to 100 angstroms. For example, the thickness of the first Ti layer is 50 angstroms.

[0162] Exemplarily, the thickness of the Al layer is 10000 angstroms to 20000 angstroms. For example, the thickness of the Al layer is 15000 angstroms.

[0163] Exemplarily, the thickness of the second Ti layer is 500 angstroms to 1500 angstroms. For example, the thickness of the second Ti layer is 1000 angstroms.

[0164] Exemplarily, the thickness of the Pt layer is 500 angstroms to 1500 angstroms. For example, the thickness of the Pt layer is 1000 angstroms.

[0165] Exemplarily, the thickness of the Ni layer is 60,000 angstroms to 80,000 angstroms. For example, the thickness of the Ni layer is 70,000 angstroms.

[0166] Exemplarily, the thickness of the Au layer is 1500 angstroms to 2500 angstroms. For example, the thickness of the Au layer is 2000 angstroms.

[0167] The experimental data of the light emitting diode provided by the embodiment of the present disclosure are as follows in Table 1:

[0168] Table 1

[0169]

[0170] According to the test results in Table 1, the average brightness of the light-emitting diode provided in the embodiment of the present disclosure is 1136.7, while the average brightness of the light-emitting diode in the related art is 1119.9. It can be seen that under the same working environment, the light-emitting diode provided in the present disclosure has a higher brightness, which is 1.5% higher than the brightness of the light-emitting diode in the related art, indicating that the light-emitting brightness of the light-emitting diode provided in the embodiment of the present disclosure is higher.

[0171] 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 method for preparing a light emitting diode, characterized in that: The preparation method comprises: forming an epitaxial layer; Using an ion source to perform plasma bombardment on the surface of the epitaxial layer; A reflective layer is evaporated on the surface of the epitaxial layer to form an electrode.

2. The preparation method according to claim 1, characterized in that: Using an ion source to perform plasma bombardment on the surface of the epitaxial layer includes: The working power of the ion source is controlled to be 500W to 700W, the working pressure in the reaction chamber is controlled to be less than or equal to 0.01Pa, and the working time is controlled to be 200s to 300s, so as to perform plasma bombardment on the surface of the epitaxial layer.

3. The preparation method according to claim 2, characterized in that: The ion source is a microwave electron cyclotron resonance plasma source.

4. The preparation method according to any one of claims 1 to 3, characterized in that: Vapor depositing a reflective layer on the surface of the epitaxial layer to form an electrode comprises: Depositing a reflective layer on the surface of the epitaxial layer, wherein the reflective layer comprises at least one of an Al layer and an Ag layer; Vapor-depositing a wrapping layer on the surface of the reflective layer, wherein the wrapping layer includes at least one of a Ni layer, a Pt layer, an Au layer, an Al layer and an AlCu layer; A protective layer is evaporated on the surface of the wrapping layer, wherein the protective layer includes at least one of a Ni layer, a Pt layer and a Ti layer.

5. The preparation method according to claim 4, characterized in that: Vapor depositing a reflective layer on the surface of the epitaxial layer comprises: Controlling the evaporation rate to be 4 angstroms / second to 6 angstroms / second, and evaporating an Al layer of 1500 angstroms to 2500 angstroms; The evaporation coating layer on the surface of the reflective layer comprises: Controlling the evaporation rate to be 1 angstrom / second to 3 angstroms / second, and evaporating a Ti layer of 300 angstroms to 700 angstroms; Controlling the evaporation rate to be 4 angstroms / second to 6 angstroms / second, and evaporating a Ni layer of 800 angstroms to 1200 angstroms; Controlling the evaporation rate to be 4 angstroms / second to 6 angstroms / second, and evaporating a Pt layer of 1500 angstroms to 2500 angstroms; Controlling the evaporation rate to be 6 angstroms / second to 10 angstroms / second, and evaporating a 6000 angstrom to 10000 angstrom Au layer; The protective layer deposited on the surface of the wrapping layer comprises: Controlling the evaporation rate to be 1 angstrom / second to 3 angstroms / second, and evaporating a Pt layer of 1500 angstroms to 2500 angstroms; The evaporation rate is controlled to be 1 angstrom / second to 3 angstroms / second, and a Ti layer of 300 angstroms to 700 angstroms is evaporated.

6. A light emitting diode, characterized in that: The light emitting diode comprises: an epitaxial layer (20) and an electrode (30), wherein the electrode (30) comprises a reflective layer (31), wherein the reflective layer (31) is stacked on the surface of the epitaxial layer (20), and the reflective layer (31) directly contacts the epitaxial layer (20).

7. The light emitting diode according to claim 6, characterized in that: The contact resistance between the interface of the reflective layer (31) and the surface of the epitaxial layer (20) is less than or equal to 0.3Ω / □.

8. The light emitting diode according to claim 6, characterized in that: The electrode (30) further comprises a wrapping layer (32) and a protective layer (33), and the reflective layer (31), the wrapping layer (32) and the protective layer (33) are sequentially stacked on the surface of the epitaxial layer (20); The reflective layer (31) includes at least one of an Al layer and an Ag layer, the wrapping layer (32) includes at least one of a Ni layer, a Pt layer, an Au layer, an Al layer and an AlCu layer, and the protective layer (33) includes at least one of a Ni layer, a Pt layer and a Ti layer.

9. The light emitting diode according to claim 8, characterized in that: The reflective layer (31) comprises an Al layer, and the thickness of the Al layer in the reflective layer (31) is 1500 angstroms to 2500 angstroms; The wrapping layer (32) comprises a Ti layer, a Ni layer, a Pt layer and an Au layer stacked in sequence, the thickness of the Ti layer in the wrapping layer (32) is 300 to 700 angstroms, the thickness of the Ni layer in the wrapping layer (32) is 800 to 1200 angstroms, the thickness of the Pt layer in the wrapping layer (32) is 1500 to 2500 angstroms, and the thickness of the Au layer in the wrapping layer (32) is 6000 to 10000 angstroms; The protective layer (33) comprises a Pt layer and a Ti layer stacked in sequence, the thickness of the Pt layer in the protective layer (33) is 1500 angstroms to 2500 angstroms, and the thickness of the Ti layer in the protective layer (33) is 300 angstroms to 700 angstroms.

10. The light emitting diode according to any one of claims 6 to 9, 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) which are stacked in sequence, and the surface of the second semiconductor layer (23) has a groove (24) exposing the first semiconductor layer (21); The electrode (30) is at least located in the groove (24) and is electrically connected to the first semiconductor layer (21). The first semiconductor layer (21) is Al x Ga (1-x) N material layer, wherein X is greater than or equal to 0 and less than or equal to 1.

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