Method for manufacturing light emitting diode with improved brightness

Abstract

The application discloses a preparation method of a light-emitting diode with improved brightness, which comprises the following steps in sequence: performing desorption treatment on a substrate, growing an AlN buffer layer, a u-GaN layer, a Si heavily doped n-GaN layer, a Si lightly doped n-GaN layer, an InGaN / GaN stress adjusting layer, a multi-quantum well layer, an AIGaN layer, a Mg doped p-GaN layer and a heavily doped p-GaN contact layer on the substrate. In the multi-quantum well layer, Ag nanoparticles and air cavity structures are formed, the local surface plasmon frequency generated by the Ag nanoparticles is effectively coupled with the multi-quantum well, the light-emitting efficiency of the LED is improved, the propagation path of the photons generated by the multi-quantum well is changed by the refraction and reflection of the air cavity, and the light-emitting efficiency is further improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, and specifically relates to a method for preparing a light-emitting diode to improve brightness. Background Technology

[0002] A light-emitting diode (LED) is a semiconductor electronic device that converts electrical energy into light energy. As a highly efficient, environmentally friendly, and green new solid-state lighting source, LEDs have been widely used in traffic lights, automotive lights, indoor and outdoor lighting, and displays. Beyond lighting, LED applications have expanded to various other fields, including sterilization, medical treatment, biomedicine, polymer printing, barcode verification, body fluid detection and analysis, water sterilization, and optical sensors.

[0003] Currently, LEDs still have relatively low photoelectric conversion efficiency in mid-to-high-end applications such as displays, sterilization, medical treatment, and polymer printing. If their luminous efficiency can be improved, LEDs will have greater room for development.

[0004] Therefore, providing a method for manufacturing light-emitting diodes to improve brightness and enhance luminous efficiency to meet the application needs of LEDs is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This application enhances LED luminous efficiency by forming Ag nanoparticles and an air cavity structure inside a multi-quantum-well layer and effectively coupling the local surface plasmon frequency generated by the Ag nanoparticles with the multi-quantum-well. At the same time, the air cavity is used to change the propagation path of photons generated by the multi-quantum-well by refraction and reflection, thereby further improving luminous efficiency.

[0006] This invention discloses a method for fabricating a light-emitting diode (LED) with improved brightness, characterized by the following steps:

[0007] Step 1: Place the substrate into the MOCVD reaction chamber for desorption treatment;

[0008] Step 2: Sequentially grow an AlN buffer layer, a u-GaN layer, a heavily doped Si n-GaN layer, and a lightly doped Si n-GaN layer on the substrate;

[0009] Step 3: Grow an InGaN / GaN stress-regulating layer on a lightly doped Si n-GaN layer. During the growth process, the molar content of In atoms is gradually reduced to reduce the stress during the material growth process.

[0010] Step 4: Grow a multi-quantum-well layer on the InGaN / GaN stress-tuning layer;

[0011] Step 5: Remove the substrate with multiple quantum well layers from the MOCVD reaction chamber. First, a circular pattern is formed on the surface of the multiple quantum well layers using photolithography. Then, the pattern is etched using ICP etching to form holes in the multiple quantum well layers.

[0012] Step Six: Fill the pores in the multi-quantum-well layer with Ag nanoparticles, and control the volume of the portion above the pores not filled with Ag nanoparticles to be between one-third and one-half of the total pore volume, specifically:

[0013] Ag nanoparticles were filled into the pores using a spin coating method, and the Ag nanoparticles were attached to the sidewalls of the pores to make direct contact with the multiple quantum wells. Then, the surface of the multiple quantum well layer was wiped with an alcohol swab to ensure that no residual Ag nanoparticles remained on the surface of the multiple quantum well layer and that the Ag nanoparticles in the pores were effectively retained to reduce the loss of light output.

[0014] Step 7: Grow an AIGaN layer on the multi-quantum well layer with internal pores. During the growth process, control the lateral growth rate to be greater than the vertical growth rate to bury the pores inside the multi-quantum well layer, so as to achieve rapid merging of the AIGaN layer and thus form an air cavity inside the multi-quantum well layer.

[0015] Step 8: Grow a Mg-doped p-GaN layer and a heavily doped p-GaN contact layer sequentially on the AlGaN layer to form a light-emitting diode with Ag nanoparticles and an air cavity inside, thereby improving the luminous efficiency.

[0016] Furthermore, the substrate is sapphire, silicon, silicon carbide, gallium nitride, or aluminum nitride, which are suitable for epitaxial growth.

[0017] Furthermore, the step three involves gradually reducing the molar content of In atoms, specifically as follows:

[0018] During the growth process, the molar content of In atoms was controlled to be uniformly reduced from 3% to 0.5%.

[0019] Furthermore, the diameter of the circular pattern in step five is 1-2 μm, and the distance between the centers of two adjacent circular patterns is 4-8 μm.

[0020] Furthermore, the diameter of the hole in step five is 1-2 μm, and the depth is 200-500 nm.

[0021] Furthermore, the Ag nanoparticles in step six have a diameter of 40-60 nm and a relatively rough surface.

[0022] Furthermore, step seven, which controls the lateral growth rate to be greater than the vertical growth rate, specifically involves:

[0023] Control the lateral growth rate to be 2-4 times the vertical growth rate.

[0024] Compared with the prior art, the method for fabricating a light-emitting diode with improved brightness of the present invention achieves the following beneficial effects:

[0025] 1. This application enhances LED luminous efficiency by forming Ag nanoparticles and an air cavity structure within a multi-quantum well layer. Firstly, the localized surface plasmon frequency generated by the Ag nanoparticles is effectively coupled to the multi-quantum wells, thereby improving luminous efficiency. The relatively rough surface of the Ag nanoparticles ensures that energy coupled to the localized surface plasmons loses momentum, effectively extracting photons from the metal / semiconductor interface and thus improving luminous efficiency. Secondly, due to the significant difference in refractive index between GaN (n=2.5) and air (n=1), the critical angle is only 23.6°. This means that only photons with an exit angle less than the critical angle can escape into the air from the multi-quantum well layer. Other photons, even after reflection from the substrate, struggle to escape. Introducing the air cavity structure alters the propagation path of these photons during downward propagation, allowing them to exit into the air after multiple reflections or refractions from the substrate or other materials, thus improving light extraction efficiency.

[0026] 2. By growing an InGaN / GaN stress-adjusting layer before growing a multi-quantum-well layer and gradually reducing the molar content of In atoms during the growth process, stress and defects caused by lattice mismatch or thermal mismatch can be reduced, dislocation derivation can be blocked, and dislocations derived from the bottom layer can be reduced, thereby improving crystal quality, thus improving the luminous efficiency of LEDs, and enhancing antistatic capability.

[0027] 3. After filling the pores with Ag nanoparticles, this application uses an alcohol swab to wipe the surface of the multi-quantum well layer, which can ensure that no residual Ag nanoparticles remain on the surface of the multi-quantum well layer, and that the Ag nanoparticles in the pores are effectively retained, which can effectively reduce the loss of light output and thus help improve the luminous efficiency of LEDs.

[0028] Of course, any product implementing this invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0029] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0030] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0031] Figure 1 The diagram shown is a structural diagram of a method for fabricating a light-emitting diode to improve brightness according to an embodiment of this application.

[0032] Illustration: 1. Substrate, 2. AlN buffer layer, 3. u-GaN layer, 4. Heavily doped Si n-GaN layer, 5. Lightly doped Si n-GaN layer, 6. InGaN / GaN stress-adjusting layer, 7. Multiple quantum well layer, 8. Ag nanoparticles, 9. AlGaN layer, 10. Air cavity, 11. Mg-doped p-GaN layer, 12. Heavily doped p-GaN contact layer. Detailed Implementation

[0033] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0034] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0035] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0036] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0038] The method for manufacturing a light-emitting diode to improve brightness described in this embodiment includes the following steps:

[0039] Step 101: Place the sapphire substrate 1 into the MOCVD reaction chamber for desorption treatment.

[0040] Step 102: Sequentially grow an AlN buffer layer 2, a u-GaN layer 3, a Si heavily doped n-GaN layer 4, and a Si lightly doped n-GaN layer 5 on the sapphire substrate 1.

[0041] Step 103: Grow an InGaN / GaN stress-adjusting layer 6 on the Si lightly doped n-GaN layer 5. During the growth process, control the molar content of In atoms to uniformly reduce from 3% to 0.5% to reduce the stress during the material growth process.

[0042] Step 104: Grow a multi-quantum well layer 7 on the InGaN / GaN stress-tuning layer 6;

[0043] Step 105: Take the sapphire substrate 1 with multiple quantum well layers 7 grown from the MOCVD reaction chamber. First, a circular pattern with a diameter of 1-2 μm and a center-to-center distance of 4-8 μm is formed on the surface of the multiple quantum well layers 7 by photolithography. Then, the photolithographic pattern is etched by ICP etching to form holes with a diameter of 1-2 μm and a depth of 200-500 nm on the multiple quantum well layers 7.

[0044] Step 106: Fill the pores in the multi-quantum-well layer 7 with Ag nanoparticles 8, and control the volume of the portion above the pores not filled with Ag nanoparticles 8 to be between one-third and one-half of the total pore volume, specifically:

[0045] Ag nanoparticles 8 are filled into the pores using a spin-coating method. First, a sapphire substrate 1 with pores on its upper surface is fixed on a spin coater. An ethanol solution containing Ag nanoparticles 8 is spin-coated onto the upper surface of a multi-quantum well layer 7 with pores inside. Centrifugal force and gravity are used to fill the pores with Ag nanoparticles 8, and Ag nanoparticles 8 are attached to the sidewalls of the pores to make close contact with the multi-quantum wells. Then, the surface of the multi-quantum well layer 7 is wiped with an alcohol swab to ensure that no residual Ag nanoparticles 8 remain on the surface of the multi-quantum well layer 7, and that the Ag nanoparticles 8 in the pores are effectively retained to reduce light output loss.

[0046] Step 107: Grow an AlGaN layer 9 on the multi-quantum well layer 7 with internal pores. During the growth process, control the lateral growth rate to be 2-4 times the vertical growth rate to bury the pores inside the multi-quantum well layer 7, so as to achieve rapid merging of the AlGaN layer 9 and thus form an air cavity 10 inside the multi-quantum well layer 7.

[0047] Step 108: A Mg-doped p-GaN layer 11 and a heavily doped p-GaN contact layer 12 are sequentially grown on the AlGaN layer 9 to form a fully structured light-emitting diode. By forming Ag nanoparticles and an air cavity structure inside the multi-quantum well layer, the local surface plasmon frequency generated by the Ag nanoparticles is effectively coupled with the multi-quantum well, thereby enhancing the luminous efficiency of the LED. At the same time, the refraction and reflection of photons by the air cavity changes the propagation path of photons generated by the multi-quantum well, further improving the luminous efficiency.

[0048] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for fabricating a light-emitting diode with improved brightness, characterized by the following steps: Step 1: Place the substrate into the MOCVD reaction chamber for desorption treatment; Step 2: Sequentially grow an AlN buffer layer, a u-GaN layer, a heavily doped Si n-GaN layer, and a lightly doped Si n-GaN layer on the substrate. Step 3: Grow an InGaN / GaN stress-regulating layer on a lightly doped Si n-GaN layer. During the growth process, the molar content of In atoms is gradually reduced to reduce the stress during the material growth process. Step 4: Grow a multi-quantum-well layer on the InGaN / GaN stress-tuning layer; Step 5: Remove the substrate with multiple quantum well layers from the MOCVD reaction chamber. First, a circular pattern is formed on the surface of the multiple quantum well layers using photolithography. Then, the pattern is etched using ICP etching to form holes in the multiple quantum well layers. Step Six: Fill the pores in the multi-quantum-well layer with Ag nanoparticles, and control the volume of the portion above the pores not filled with Ag nanoparticles to be between one-third and one-half of the total pore volume, specifically: Ag nanoparticles were filled into the pores using a spin coating method, and the Ag nanoparticles were attached to the sidewalls of the pores to make direct contact with the multiple quantum wells. Then, the surface of the multiple quantum well layer was wiped with an alcohol swab to ensure that no residual Ag nanoparticles remained on the surface of the multiple quantum well layer and that the Ag nanoparticles in the pores were effectively retained to reduce the loss of light output. Step 7: Grow an AIGaN layer on the multi-quantum well layer with internal pores. During the growth process, control the lateral growth rate to be greater than the vertical growth rate to bury the pores inside the multi-quantum well layer, so as to achieve rapid merging of the AIGaN layer and thus form an air cavity inside the multi-quantum well layer. Step 8: Grow a Mg-doped p-GaN layer and a heavily doped p-GaN contact layer sequentially on the AlGaN layer to form a light-emitting diode with Ag nanoparticles and an air cavity inside, thereby improving the luminous efficiency.

2. The method for preparing a light-emitting diode with improved brightness according to claim 1, characterized in that, The substrate is sapphire, silicon, silicon carbide, gallium nitride, or aluminum nitride, which are suitable for epitaxial growth.

3. The method for preparing a light-emitting diode with improved brightness according to claim 1, characterized in that, The step three, controlling the gradual decrease of the molar content of In atoms, specifically involves: During the growth process, the molar content of In atoms was controlled to be uniformly reduced from 3% to 0.5%.

4. The method for preparing a light-emitting diode with improved brightness according to claim 1, characterized in that, The diameter of the circular pattern in step five is 1-2 μm, and the distance between the centers of two adjacent circular patterns is 4-8 μm.

5. The method for preparing a light-emitting diode with improved brightness according to claim 1, characterized in that, The diameter of the hole in step five is 1-2 μm, and the depth is 200-500 nm.

6. The method for preparing a light-emitting diode with improved brightness according to claim 1, characterized in that, The Ag nanoparticles obtained in step six have a diameter of 40-60 nm and a relatively rough surface.

7. The method for preparing a light-emitting diode with improved brightness according to claim 1, characterized in that, Step seven, which involves controlling the lateral growth rate to be greater than the vertical growth rate, specifically involves: Control the lateral growth rate to be 2-4 times the vertical growth rate.

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