Light emitting diode capable of improving brightness and preparation method thereof
By using nanoscale silver nanolayers as ohmic contact films in light emitting diodes to replace the transparent conductive layer, the problem of light absorption by the transparent conductive layer is solved, and the brightness is improved.
Patent Information
- Application Number
- CN202411162644.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-23
- Publication Date
- 2025-01-14
AI Technical Summary
The transparent conductive layer in the existing light emitting diodes has an absorbing effect on light, resulting in a decrease in brightness.
A nanoscale silver nanolayer is used as an ohmic contact film to replace the transparent conductive layer, and the ohmic contact between the silver nanolayer and the metal reflective layer is reduced to reduce resistance and light absorption.
The light output and brightness of the light emitting diodes have been improved, which is 2.66% higher than traditional technology.
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Figure CN119317265A_ABST
Abstract
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 generally includes an epitaxial layer and a silver mirror reflective layer disposed on the surface of the epitaxial layer. Since the contact between metal Ag and the epitaxial layer is a Schottky contact, the resistance of the LED will be very large. Therefore, a transparent conductive layer is generally disposed between the epitaxial layer and the silver mirror reflective layer, and ohmic contacts are formed with the epitaxial layer and the silver mirror reflective layer respectively through the transparent conductive layer to facilitate current transmission.
[0004] However, the transparent conductive layer has a certain absorption effect on light, thus affecting the light output of the light emitting diode, thereby reducing the brightness of the light emitting diode. 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 prevent the transparent conductive layer from absorbing light 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 light-emitting diode, which includes: an epitaxial layer, an ohmic contact film and a metal reflective layer; the ohmic contact film includes a silver nanolayer, the silver nanolayer is located on the surface of the epitaxial layer, the metal reflective layer is located on a side of the silver nanolayer away from the epitaxial layer, and the metal reflective layer is connected to the silver nanolayer.
[0007] Optionally, the thickness of the silver nanolayer is 10 nm to 20 nm.
[0008] Optionally, the ohmic contact film also includes an insulating protective layer, which is located on the surface of the silver nanolayer away from the epitaxial layer, and has a first through hole exposing the silver nanolayer; the metal reflective layer is located on a side of the insulating protective layer away from the epitaxial layer, and the metal reflective layer is connected to the silver nanolayer through the first through hole.
[0009] Optionally, the insulating protection layer includes an aluminum oxide layer.
[0010] Optionally, the insulating protection layer has a thickness of 300 angstroms to 800 angstroms.
[0011] Optionally, the light-emitting diode also includes an insulating reflective layer, which is located on the surface of the insulating protection layer away from the epitaxial layer, and has a second through hole exposing the first through hole; the metal reflective layer is located on the surface of the insulating reflective layer away from the epitaxial layer, and the metal reflective layer is connected to the silver nanolayer via the second through hole and the first through hole in sequence.
[0012] Optionally, the ohmic contact film further includes a metal contact layer, the metal contact layer is located between the silver nanolayer and the epitaxial layer, and the metal contact layer includes at least one of a Ti layer, a Ni layer and a Cr layer.
[0013] On the other hand, an embodiment of the present disclosure provides a method for preparing a light-emitting diode, the method comprising: forming an epitaxial layer; forming an ohmic contact film on the surface of the epitaxial layer, the ohmic contact film comprising a silver nanolayer; forming a metal reflective layer on a side of the silver nanolayer away from the epitaxial layer, the metal reflective layer being connected to the silver nanolayer.
[0014] Optionally, forming an ohmic contact film on the surface of the epitaxial layer comprises: using an ion source to perform plasma bombardment on the surface of the epitaxial layer; and evaporating the silver nanolayer on the surface of the epitaxial layer.
[0015] 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.
[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 has an ohmic contact layer between the epitaxial layer and the metal reflective layer, and the ohmic contact layer replaces the transparent conductive layer in the related art. Among them, the ohmic contact layer adopts a nano-scale silver nanolayer. When the thinner silver nanolayer contacts the epitaxial layer, the resistance at the interface between the silver nanolayer and the epitaxial layer will not be very large, so that the current can be smoothly transmitted from the silver nanolayer to the epitaxial layer. In addition, the silver nanolayer has a weaker absorption effect on light, and compared with the transparent conductive layer, it can reduce the absorption of light by the light-emitting diode, thereby increasing the light output of the light-emitting diode, thereby 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 top view of a light emitting diode provided by an embodiment of the present disclosure;
[0020] Figure 2 yes Figure 1 An AA cross-sectional view is provided;
[0021] Figure 3 It is a flow chart of a method for preparing a light emitting diode 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;
[0025] 30. Ohmic contact film; 31. Silver nanolayer; 32. Insulating protection layer; 320. First through hole;
[0026] 41. Metal reflective layer; 42. Enveloping layer;
[0027] 51. Insulating reflective layer; 510. Second through hole;
[0028] 61. a first passivation layer; 62. a second passivation layer;
[0029] 71. Electrode; 72. 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 It is a top view of a light emitting diode provided by an embodiment of the present disclosure. Figure 2 yes Figure 1 An AA cross-section diagram is provided. Figure 1 , 2 As shown, the light emitting diode includes: an epitaxial layer 20 , an ohmic contact film 30 and a metal reflective layer 41 .
[0033] like Figure 2 As shown, the ohmic contact film 30 includes a silver nanolayer 31 , which is located on the surface of the epitaxial layer 20 , and a metal reflective layer 41 is located on a side of the silver nanolayer 31 away from the epitaxial layer 20 , and the metal reflective layer 41 is connected to the silver nanolayer 31 .
[0034] The light-emitting diode provided by the embodiment of the present disclosure is provided with an ohmic contact layer between the epitaxial layer 20 and the metal reflective layer 41, and the transparent conductive layer in the related art is replaced by the ohmic contact layer. Among them, the ohmic contact layer adopts a nano-scale silver nanolayer 31. When the thinner silver nanolayer 31 contacts the epitaxial layer 20, the resistance at the interface between the silver nanolayer 31 and the epitaxial layer 20 will not be very large, so that the current can be smoothly transmitted from the silver nanolayer 31 to the epitaxial layer 20. In addition, the silver nanolayer 31 has a weaker absorption effect on light, and compared with the transparent conductive layer, it can reduce the absorption of light by the light-emitting diode, thereby increasing the light output of the light-emitting diode, thereby improving the brightness of the light-emitting diode.
[0035] Optionally, the thickness of the silver nano-layer 31 is 10 nm to 20 nm.
[0036] By controlling the thickness of the silver nanolayer 31 within the above range, a nanoscale silver nanolayer 31 can be formed. When the thinner silver nanolayer 31 contacts the epitaxial layer 20, the resistance at the interface between the silver nanolayer 31 and the epitaxial layer 20 will not be very large, so that the current can be smoothly transmitted from the silver nanolayer 31 to the epitaxial layer 20, thereby replacing the transparent conductive layer and realizing the ohmic contact between the metal reflective layer 41 and the epitaxial layer 20.
[0037] Exemplarily, the thickness of the silver nanolayer 31 is 15 nm.
[0038] Alternatively, if Figure 2 As shown, the ohmic contact film 30 further includes an insulating protection layer 32 . The insulating protection layer 32 is located on a surface of the silver nano-layer 31 away from the epitaxial layer 20 . The insulating protection layer 32 has a first through hole 320 exposing the silver nano-layer 31 .
[0039] like Figure 2 As shown, the metal reflective layer 41 is located on a side of the insulating protection layer 32 away from the epitaxial layer 20 , and the metal reflective layer 41 is connected to the silver nanolayer 31 through the first through hole 320 .
[0040] An insulating protective layer 32 covering the silver nanolayer 31 is formed on the surface of the silver nanolayer 31 away from the epitaxial layer 20, which can protect the silver nanolayer 31 and prevent the metal Ag in the silver nanolayer 31 from migrating outward during the preparation process. At the same time, the silver nanolayer 31 is wrapped with the insulating protective layer 32, and a first through hole 320 is formed on the insulating protective layer 32, so that the metal reflective layer 41 is electrically connected to the silver nanolayer 31 through the first through hole 320, which not only meets the current transmission requirement of the silver nanolayer 31, but also avoids the problem of the silver nanolayer 31 being too exposed and in contact with other film layers, resulting in a short circuit of the silver nanolayer 31.
[0041] Optionally, the insulating protection layer 32 includes an aluminum oxide layer. The aluminum oxide layer has a good insulating effect and can prevent the silver nano-layer 31 from being short-circuited with other film layers. The aluminum oxide layer has good stability and can protect the silver nano-layer 31.
[0042] Optionally, the thickness of the insulating protection layer 32 is 300 angstroms to 800 angstroms.
[0043] The thickness of the through hole insulating protection layer 32 is within the above range, which can prevent the insulating protection layer 32 from being too thick and absorbing a large amount of light, and can also prevent the insulating protection layer 32 from being too thin and failing to protect the silver nano-layer 31 .
[0044] By way of example, the thickness of the insulating protection layer 32 may be 500 angstroms.
[0045] Alternatively, if Figure 2As shown, the light emitting diode further includes an insulating reflective layer 51 . The insulating reflective layer 51 is located on a surface of the insulating protection layer 32 away from the epitaxial layer 20 . The insulating reflective layer 51 has a second through hole 510 exposing the first through hole 320 .
[0046] like Figure 2 As shown, the metal reflective layer 41 is located on the surface of the insulating reflective layer 51 away from the epitaxial layer 20 , and the metal reflective layer 41 is connected to the silver nanolayer 31 through the second through hole 510 and the first through hole 320 in sequence.
[0047] Exemplarily, the insulating reflective layer 51 may be a DBR (Distributed Bragg Reflector) layer.
[0048] The DBR layer includes a plurality of silicon oxide layers and a plurality of titanium oxide layers stacked alternately, and the thickness of the DBR layer is 3 μm to 4 μm.
[0049] By providing the insulating reflective layer 51 , the light emitted from the epitaxial layer 20 can be reflected, 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.
[0050] Optionally, the metal reflective layer 41 includes an Ag layer, a Ni layer, and a TiW layer stacked in sequence.
[0051] Since Ag has a good reflective effect, providing an Ag layer in the reflective layer can enhance the reflection of light by the reflective layer and improve the light emitting brightness of the light emitting surface of the light emitting diode.
[0052] 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.
[0053] Exemplarily, the thickness of the Ag layer is 1400 angstroms to 1700 angstroms. For example, the thickness of the Ag layer is 1500 angstroms.
[0054] Exemplarily, the thickness of the Ni layer is 100 angstroms to 300 angstroms. For example, the thickness of the Ni layer is 200 angstroms.
[0055] Exemplarily, the thickness of the TiW layer is 700 angstroms to 1000 angstroms. For example, the thickness of the TiW layer is 800 angstroms.
[0056] Alternatively, if Figure 2 As shown, the light emitting diode further includes a surrounding layer 42 , which is located on a surface of the insulating reflective layer 51 away from the epitaxial layer 20 and covers the metal reflective layer 41 .
[0057] By covering the metal reflective layer 41 with a surrounding layer 42 , the metal in the metal reflective layer 41 can be prevented from migrating upward.
[0058] Optionally, the surrounding layer 42 includes an aluminum oxide layer. Exemplarily, the thickness of the aluminum oxide layer is 500 angstroms to 1000 angstroms.
[0059] 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 .
[0060] Exemplarily, the substrate is 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.
[0061] In the disclosed embodiment, the epitaxial layer 20 includes a first semiconductor layer, a multi-quantum well layer, and a second semiconductor layer sequentially stacked on a substrate, and a surface of the second semiconductor layer has a groove exposing the first semiconductor layer.
[0062] In the embodiment of the present disclosure, one of the first semiconductor layer and the second semiconductor layer is a p-type layer, and the other of the first semiconductor layer and the second semiconductor layer is an n-type layer.
[0063] Exemplarily, the first semiconductor layer is an n-type layer, and the second semiconductor layer is a p-type layer.
[0064] In the implementation of the present disclosure, 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.
[0065] Exemplarily, when X is 0, the first semiconductor layer is a GaN layer. For example, the first semiconductor layer is a silicon-doped n-type GaN layer. The thickness of the n-type GaN layer may be 0.5 μm to 3 μm.
[0066] 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.
[0067] 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.
[0068] Optionally, the thickness of the multi-quantum well layer may be 150 nm to 200 nm.
[0069] 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.
[0070] Optionally, the second semiconductor layer has a groove exposing the first semiconductor layer.
[0071] Alternatively, if Figure 2 As shown, the light emitting diode further includes: a first passivation layer 61 and an electrode 71 . The first passivation layer 61 is located on the surface of the surrounding layer 42 and in the groove.
[0072] Among them, the surface of the first passivation layer 61 has a through hole exposing the metal reflective layer 41 and the bottom of the groove, and the through hole also penetrates the through hole of the surrounding layer 42. The electrode 71 is located on the surface of the first passivation layer 61 and is connected to the metal reflective layer 41 and the first semiconductor layer respectively through the through hole.
[0073] Exemplarily, the first passivation layer 61 may be a silicon oxide layer.
[0074] Exemplarily, the thickness of the first passivation layer 61 is 4000 angstroms to 6000 angstroms.
[0075] Exemplarily, the electrode 71 may include at least one of an Al layer, an Ag layer, a Ni layer, a Pt layer, an Au layer, and an AlCu layer.
[0076] For example, the electrode 71 may include an Al layer, a Ti layer, a Ni layer, a Pt layer, and an Au layer stacked in sequence.
[0077] Illustratively, the thickness of the Al layer is 1500 angstroms to 2500 angstroms.
[0078] Illustratively, the thickness of the Ti layer is 300 angstroms to 700 angstroms.
[0079] Illustratively, the Ni layer has a thickness of 800 angstroms to 1200 angstroms.
[0080] Illustratively, the thickness of the Pt layer is 1500 angstroms to 2500 angstroms.
[0081] Illustratively, the Au layer has a thickness of 6000 angstroms to 10000 angstroms.
[0082] Alternatively, if Figure 2 As shown, the light emitting diode may further include a second passivation layer 62 and a pad 72, wherein the second passivation layer 62 is located on the surface of the first passivation layer 61 and covers the electrode 71. The second passivation layer 62 has a through hole exposing the electrode 71, and the pad 72 is located on the surface of the second passivation layer 62 away from the epitaxial layer 20, and the pad 72 is electrically connected to the electrode 71 through the through hole.
[0083] Optionally, the pad 72 includes at least one of a Ti layer, an Al layer, a Pt layer, a Ni layer, and an Au layer.
[0084] The above metal material has good heat dissipation performance. Therefore, the solder pad 7260 made of the above material also has good heat dissipation performance and can improve the heat dissipation effect of the light emitting diode.
[0085] Alternatively, the pad 72 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.
[0086] 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.
[0087] Exemplarily, the thickness of the Al layer is 10000 angstroms to 20000 angstroms. For example, the thickness of the Al layer is 15000 angstroms.
[0088] 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.
[0089] Exemplarily, the thickness of the Pt layer is 500 angstroms to 1500 angstroms. For example, the thickness of the Pt layer is 1000 angstroms.
[0090] 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.
[0091] Exemplarily, the thickness of the Au layer is 1500 angstroms to 2500 angstroms. For example, the thickness of the Au layer is 2000 angstroms.
[0092] Optionally, the ohmic contact film 30 further includes a metal contact layer, the metal contact layer is located between the silver nanolayer 31 and the epitaxial layer 20 , and the metal contact layer includes at least one of a Ti layer, a Ni layer, and a Cr layer.
[0093] By forming a Ti layer, a Ni layer or a Cr layer as a contact layer between the epitaxial layer 20 and the silver nanolayer 31, ohmic contact between the epitaxial layer 20 and the silver nanolayer 31 can be achieved, thereby reducing resistance and improving the light emitting effect of the light emitting diode.
[0094] Exemplarily, the metal contact layer includes a Ti layer, a Ni layer, and a Cr layer stacked in sequence.
[0095] Figure 3 FIG. 1 is a flow chart of a method for preparing a light emitting diode provided by an embodiment of the present disclosure. Figure 3 As shown, the preparation method comprises:
[0096] Step S11: forming an epitaxial layer.
[0097] Step S12: forming an ohmic contact film on the surface of the epitaxial layer.
[0098] Wherein, the ohmic contact film includes a silver nanolayer.
[0099] Step S13: forming a metal reflective layer on a side of the silver nanolayer away from the epitaxial layer.
[0100] Wherein, the metal reflective layer is connected to the silver nanolayer.
[0101] The light-emitting diode prepared by the preparation method provided in the embodiment of the present disclosure has an ohmic contact layer arranged between the epitaxial layer and the metal reflective layer, and the transparent conductive layer in the related art is replaced by the ohmic contact layer. Among them, the ohmic contact layer adopts a nano-scale silver nanolayer. When the thinner silver nanolayer contacts the epitaxial layer, the resistance at the interface between the silver nanolayer and the epitaxial layer will not be very large, so that the current can be smoothly transmitted from the silver nanolayer to the epitaxial layer. In addition, the silver nanolayer has a weaker absorption effect on light, and compared with the transparent conductive layer, it can reduce the absorption of light by the light-emitting diode, thereby increasing the light output of the light-emitting diode, thereby improving the brightness of the light-emitting diode.
[0102] The process of preparing the epitaxial layer in step S11 may include the following steps:
[0103] First, a substrate is provided.
[0104] 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.
[0105] 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.
[0106] 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.
[0107] 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.
[0108] 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.
[0109] The first semiconductor layer is an n-type layer, and the second semiconductor layer is a p-type layer.
[0110] 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.
[0111] 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.
[0112] 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.
[0113] 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.
[0114] 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.
[0115] Optionally, the thickness of the multi-quantum well layer may be 150 nm to 200 nm.
[0116] 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.
[0117] 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.
[0118] Then, the second semiconductor layer is etched to form a groove exposing the first semiconductor layer.
[0119] Step S12 may include:
[0120] First, an ion source is used to perform plasma bombardment on the surface of the epitaxial layer.
[0121] Among them, the C or O impurities on the surface of the epitaxial layer can be removed by bombarding the epitaxial layer with plasma.
[0122] Then, a silver nanolayer is evaporated on the surface of the epitaxial layer.
[0123] In the above implementation, when evaporating the silver nanolayer, the surface of the epitaxial layer is first bombarded with plasma using an ion source, and the C or O impurities on the surface of the epitaxial layer are removed by plasma. If the C or O impurities are not removed, the Ag metal in the silver nanolayer will bond 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 silver nanolayer. Before evaporating the silver nanolayer, 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 Ag metal in the silver nanolayer can better contact the epitaxial layer and 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 Ag metal in the silver nanolayer directly forms an ohmic contact with the epitaxial layer to reduce the contact resistance, thereby improving the luminous brightness of the light-emitting diode.
[0124] 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.
[0125] 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.
[0126] 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.
[0127] Optionally, the ion source is a microwave electron cyclotron resonance plasma source.
[0128] 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.
[0129] Before step S13, the method also includes: forming an insulating protection layer and an insulating reflective layer on the surface of the silver nanolayer and the surface of the epitaxial layer in sequence, and etching the surface of the insulating reflective layer to form a second through hole penetrating the insulating reflective layer and a first through hole penetrating the insulating protection layer.
[0130] Wherein, the first through hole is connected to the second through hole.
[0131] Optionally, the insulating protection layer includes an aluminum oxide layer. Exemplarily, the thickness of the insulating protection layer is 300 angstroms to 800 angstroms.
[0132] Optionally, the insulating reflective layer includes a plurality of silicon oxide layers and a plurality of titanium oxide layers alternately stacked. Exemplarily, the thickness of the insulating reflective layer is 3 μm to 4 μm.
[0133] Step S13 may include: sequentially forming an Ag layer, a Ni layer and a TiW layer on the surface of the insulating reflective layer.
[0134] Exemplarily, the thickness of the Ag layer is 1400 angstroms to 1700 angstroms. For example, the thickness of the Ag layer is 1500 angstroms.
[0135] Exemplarily, the thickness of the Ni layer is 100 angstroms to 300 angstroms. For example, the thickness of the Ni layer is 200 angstroms.
[0136] Exemplarily, the thickness of the TiW layer is 700 angstroms to 1000 angstroms. For example, the thickness of the TiW layer is 800 angstroms.
[0137] After step S13, the following steps are also included:
[0138] First, an enveloping layer is formed on the surface of the insulating reflective layer and the surface of the metal reflective layer so that the enveloping layer covers the metal reflective layer.
[0139] Optionally, the enveloping layer comprises an aluminum oxide layer. Exemplarily, the thickness of the enveloping layer is 500 angstroms.
[0140] Then, a first passivation layer is formed on the surface of the surrounding layer and in the groove.
[0141] Next, a through hole exposing the metal reflective layer and a through hole exposing the bottom of the groove are formed on the surface of the first passivation layer by photolithography.
[0142] Exemplarily, the first passivation layer may be a silicon oxide layer.
[0143] Exemplarily, the thickness of the first passivation layer is 4000 angstroms to 6000 angstroms.
[0144] Then, a second passivation layer is formed on the surface of the first passivation layer so that the second passivation layer covers the electrode.
[0145] Exemplarily, the second passivation layer is a DBR layer, 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.
[0146] Then, the second passivation layer is etched to form a through hole exposing the electrode on the surface of the second passivation layer.
[0147] Next, a pad is formed on a surface of the second passivation layer away from the epitaxial layer, and the pad is electrically connected to the electrode through the through hole.
[0148] 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.
[0149] 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.
[0150] Exemplarily, the thickness of the Al layer is 10000 angstroms to 20000 angstroms. For example, the thickness of the Al layer is 15000 angstroms.
[0151] 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.
[0152] Exemplarily, the thickness of the Pt layer is 500 angstroms to 1500 angstroms. For example, the thickness of the Pt layer is 1000 angstroms.
[0153] Exemplarily, the thickness of the Ni layer is 6000 angstroms to 8000 angstroms. For example, the thickness of the Ni layer is 7000 angstroms.
[0154] Exemplarily, the thickness of the Au layer is 1500 angstroms to 2500 angstroms. For example, the thickness of the Au layer is 2000 angstroms.
[0155] The experimental data of the light emitting diode provided by the embodiment of the present disclosure are as follows in Table 1:
[0156] Table 1
[0157]
[0158] 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 1011.1, while the average brightness of the light-emitting diode in the related art is 984.9. 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 2.66% 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.
[0159] 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), an ohmic contact film (30) and a metal reflective layer (41); The ohmic contact film (30) comprises a silver nanolayer (31), the silver nanolayer (31) is located on the surface of the epitaxial layer (20), the metal reflective layer (41) is located on a side of the silver nanolayer (31) away from the epitaxial layer (20), and the metal reflective layer (41) is connected to the silver nanolayer (31).
2. The light emitting diode according to claim 1, characterized in that: The thickness of the silver nanolayer (31) is 10 nm to 20 nm.
3. The light emitting diode according to claim 1 or 2, characterized in that: The ohmic contact film (30) further comprises an insulating protective layer (32), the insulating protective layer (32) being located on a surface of the silver nanolayer (31) away from the epitaxial layer (20), and the insulating protective layer (32) having a first through hole (320) exposing the silver nanolayer (31); The metal reflective layer (41) is located on a side of the insulating protective layer (32) away from the epitaxial layer (20), and the metal reflective layer (41) is connected to the silver nanolayer (31) through the first through hole (320).
4. The light emitting diode according to claim 3, characterized in that: The insulating protection layer (32) comprises an aluminum oxide layer.
5. The light emitting diode according to claim 3, characterized in that: The thickness of the insulating protection layer (32) is 300 angstroms to 800 angstroms.
6. The light emitting diode according to claim 4 or 5, characterized in that: The light emitting diode further comprises an insulating reflective layer (51), the insulating reflective layer (51) being located on a surface of the insulating protection layer (32) away from the epitaxial layer (20), and the insulating reflective layer (51) having a second through hole (510) exposing the first through hole (320); The metal reflective layer (41) is located on a surface of the insulating reflective layer (51) away from the epitaxial layer (20), and the metal reflective layer (41) is connected to the silver nanolayer (31) via the second through hole (510) and the first through hole (320) in sequence.
7. The light emitting diode according to any one of claims 1 to 2 and 4 to 5, characterized in that: The ohmic contact film (30) further comprises a metal contact layer, the metal contact layer is located between the silver nanolayer (31) and the epitaxial layer (20), and the metal contact layer comprises at least one of a Ti layer, a Ni layer and a Cr layer.
8. A method for preparing a light emitting diode, characterized in that: The preparation method comprises: forming an epitaxial layer; forming an ohmic contact film on a surface of the epitaxial layer, wherein the ohmic contact film comprises a silver nanolayer; A metal reflective layer is formed on a side of the silver nanolayer away from the epitaxial layer, and the metal reflective layer is connected to the silver nanolayer.
9. The preparation method according to claim 8, characterized in that: Forming an ohmic contact film on the surface of the epitaxial layer includes: Using an ion source to perform plasma bombardment on the surface of the epitaxial layer; The silver nanolayer is evaporated on the surface of the epitaxial layer.
10. The preparation method according to claim 9, 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.