Red and yellow light LED epitaxial structure for phototherapy and preparation method

Abstract

The invention provides a red and yellow light LED epitaxial structure for phototherapy and a preparation method. The red and yellow light LED epitaxial structure comprises a substrate, a graphene / GaAs buffer layer, an n-type semiconductor layer, an InGaAs / GaAs multi-quantum well light-emitting layer, a p-type semiconductor layer and a GaAs contact layer from bottom to top, wherein on the GaAs substrate, the substrate is not limited to GaAs, InP, germanium and silicon, a GaAs / graphene periodic structure is deposited to serve as a buffer layer, 3-50 periods are provided, and the optical thickness is lambda / 4; the multi-quantum well light-emitting layer comprises a red light multi-quantum well sub-layer and a yellow light multi-quantum well sub-layer which are deposited and grown in sequence from bottom to top. The graphene buffer layers are adopted to alternately prepare the LED epitaxy, the conductivity of the buffer layers is improved and the internal resistance of the chip is reduced by utilizing good conductivity and high light transmittance of graphene, so that the photoelectric conversion efficiency of the LED chip is improved; a multi-quantum well layer is adopted to generate red and yellow light for phototherapy equipment; the size is small and the current density is low.

Description

Technical Field

[0001] The present application relates to the field of LEDs and optical medical devices, and in particular to an LED epitaxial structure and a preparation method for red and yellow light for phototherapy. Background Art

[0002] Phototherapy has become a common physical therapy, effectively treating sleep disorders, depression, and other conditions. Its use as an effective treatment method dates back to 1903, when Danish scientist Finsen won the Nobel Prize in Physiology or Medicine for inventing ultraviolet light therapy to treat skin diseases. However, due to the limitations of light sources at the time, phototherapy struggled to meet treatment requirements and was therefore not widely adopted. Currently, medical phototherapy devices use light of specific wavelengths for physical therapy. To achieve the effective treatment range of phototherapy, a high optical power density per unit area is required. However, since wearable phototherapy devices are mostly applied to the skin, high optical power density LEDs can easily generate high heat, leading to burns and other problems in patients. Therefore, LED epitaxial structures with high photoelectric conversion efficiency must be used. Therefore, LED epitaxial structures suitable for small size and low current density are currently in demand. Summary of the Invention

[0003] In view of the above problems, the present invention provides an LED epitaxial structure and preparation method for red and yellow light for phototherapy. The LED epitaxial structure is prepared by alternating graphene buffer layers. The good conductivity and strong light transmittance of graphene are utilized to improve the conductivity of the buffer layer and reduce the internal resistance of the chip, thereby improving the photoelectric conversion efficiency of the LED chip. A multi-quantum well layer is used to generate red and yellow light for use in phototherapy equipment.

[0004] In a first aspect, the present invention provides an epitaxial structure and preparation method for a red-yellow light-emitting LED for phototherapy, wherein the structure comprises, from bottom to top: a substrate, a graphene / GaAs buffer layer, an n-type semiconductor layer, an InGaAs / GaAs multi-quantum well light-emitting layer, a p-type semiconductor layer, and a GaAs contact layer; wherein, on a GaAs substrate (the substrate is not limited to GaAs, InP, germanium, or silicon), a GaAs / graphene periodic structure is deposited as a buffer layer, with 3-50 periods and an optical thickness of λ / 4; the multi-quantum well light-emitting layer comprises a red light multi-quantum well sublayer and a yellow light multi-quantum well sublayer deposited and grown sequentially from bottom to top.

[0005] Furthermore, nGaAs is deposited on the GaAs / graphene buffer layer with a thickness ranging from 100 to 1000 nm and a doping concentration of 1E16 to 1E22.

[0006] Furthermore, an InGaAs / GaAs quantum well layer is deposited on the nGaAs layer, which is composed of 3 nm thick InGaAs and 4 nm thick GaAs, with a thickness ranging from 30 to 200 nm and a doping concentration of 1E16 to 1E22.

[0007] Furthermore, a p-type AlGaAs is deposited on the InGaAs / GaAs quantum well layer as an electron blocking layer with a thickness ranging from 30 to 200 nm and a doping concentration of 1E16 to 1E22.

[0008] Furthermore, a p-type GaAs contact layer is deposited on the p-type GaAs layer, with a doping concentration ranging from 1E18 to 1E22, p-type doping, and a thickness ranging from 30 to 200 nm.

[0009] In a second aspect, a method for preparing an epitaxial structure of an LED for phototherapy with red and yellow light is provided. The method is the method for preparing an epitaxial structure of an LED for phototherapy with red and yellow light described in any of the above items, characterized in that the method comprises using MOCVD / MBE / PECVD equipment to deposit a GaAs / graphene periodic structure as a buffer layer on a GaAs substrate (the substrate is not limited to GaAs, InP, germanium, or silicon), with 3-50 periods and an optical thickness of λ / 4. The structure may be n-type doped or undoped, and the GaAs doping concentration is 0-1E22; pre-treating the substrate surface with N2 / H2; heating the pre-treated substrate to 500-1000°C; introducing arsine and a gallium source to grow GaAs; switching the carbon source gas to grow graphene in an environment of 500-1000°C; and repeating the process 3-50 times. Depositing nGaAs on the GaAs / graphene buffer layer; Depositing an InGaAs / GaAs quantum well layer on the nGaAs layer; Depositing p-type AlGaAs as an electron blocking layer on the InGaAs / GaAs quantum well layer; depositing a p-type GaAs layer on the p-type AlGaAs layer; depositing a p-type GaAs contact layer on the p-type GaAs layer; Remove from heat after cooling to room temperature.

[0010] The third part is a chip of a red-yellow light LED epitaxial structure for phototherapy, characterized by adopting any of the above-mentioned red-yellow light LED epitaxial structure and preparation method thereof.

[0011] The beneficial effects of the present application are as follows: Through the above-mentioned implementation scheme, the following advantages or beneficial effects are achieved: LED epitaxy is prepared by alternating graphene buffer layers, and the good conductivity and strong transmittance of graphene are utilized to improve the conductivity of the buffer layer, reduce the internal resistance of the chip, and thus improve the photoelectric conversion efficiency of the LED chip; and a multi-quantum well layer is used to generate red and yellow light for use in phototherapy equipment; small size and low current density.

[0012] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. The purposes and other advantages of the present application can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0014] Figure 1 This is a diagram of the epitaxial structure of an LED that produces red and yellow light for phototherapy provided by the present invention. DETAILED DESCRIPTION

[0015] To make the objectives, technical solutions, and advantages of this application more clearly understood, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0016] like Figure 1The epitaxial structure of a red and yellow light LED for phototherapy is shown in the figure. The structure includes, from bottom to top: a substrate, a graphene / GaAs buffer layer, nGaAs, an InGaAs / GaAs quantum well layer, a pGaAs layer, and a GaAs contact layer. On a GaAs substrate (which is not limited to GaAs, InP, germanium, or silicon), a GaAs / graphene periodic structure is deposited as a buffer layer with 3-50 periods and an optical thickness of λ / 4. The multi-quantum well light-emitting layer includes a red multi-quantum well sublayer and a yellow multi-quantum well sublayer deposited and grown sequentially from bottom to top. nGaAs is deposited on the GaAs / graphene buffer layer with a thickness ranging from 100-1000nm and a doping concentration of 1E16-1E22. InGaAs is deposited on the nGaAs layer. The As / GaAs quantum well layer consists of 3 nm thick InGaAs and 4 nm thick GaAs, with 30 pairs of periodic structures, a thickness range of 30-200 nm, and a doping concentration of 1E16-1E22; a p-type AlGaAs is deposited on the InGaAs / GaAs quantum well layer as an electron blocking layer, with a thickness range of 30-200 nm and a doping concentration of 1E16-1E22; a p-type GaAs layer is deposited on the p-type AlGaAs layer, with a thickness range of 30-200 nm and a doping concentration of 1E16-1E22; and a p-type GaAs contact layer is deposited on the p-type GaAs layer, with a doping concentration range of 1E18-1E22, p-type doping, and a thickness range of 30-200 nm.

[0017] The preparation method adopted comprises the following steps: 1. Using MOCVD / MBE / PECVD equipment, on a GaAs substrate (substrate is not limited to GaAs, InP, germanium, or silicon), deposit a GaAs / graphene periodic structure as a buffer layer with 3-50 periods and an optical thickness of λ / 4. The structure can be n-type doped or undoped, with a GaAs doping concentration of 0-1E22; 2. Deposit nGaAs on the GaAs / graphene buffer layer with a thickness ranging from 100-1000nm and a doping concentration of 1E16-1E22; 3. Deposit an InGaAs / GaAs quantum well layer on the nGaAs layer, consisting of 3 nm thick InGaAs and 4 nm thick GaAs, 30 pairs of periodic structures, thickness range 30-200 nm, and doping concentration 1E16-1E22; 4. Deposit p-type AlGaAs as an electron blocking layer on the InGaAs / GaAs quantum well layer with a thickness ranging from 30 to 200 nm and a doping concentration of 1E16 to 1E22; 5. Deposit a p-type GaAs layer on the p-type AlGaAs layer with a thickness ranging from 30 to 200 nm and a doping concentration of 1E16 to 1E22; 6. Deposit a p-type GaAs contact layer on the p-type GaAs layer, with a doping concentration range of 1E18-1E22, p-type doping, and a thickness range of 30-200nm; 7. Remove from the container after cooling to room temperature.

[0018] In the chip of LED epitaxial structure with red and yellow light for phototherapy, the layers of epitaxial structure below the tunnel junction mainly rely on the first DBR and the second DBR to form a resonant cavity, emitting light with a narrow wavelength and a small emission angle, while the layers of epitaxial structure above the tunnel junction emit LED light with a wide wavelength and a large emission angle.

[0019] Advantages of the implementation of the present invention: Through the above-mentioned scheme, the following advantages or beneficial effects are achieved: the LED epitaxy is prepared by alternating graphene buffer layers, and the good conductivity and strong light transmittance of graphene are utilized to improve the conductivity of the buffer layer, reduce the internal resistance of the chip, and thus improve the photoelectric conversion efficiency of the LED chip; and a multi-quantum well layer is used to generate red and yellow light for use in phototherapy equipment; small size and low current density.

[0020] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A red and yellow light LED epitaxial structure for phototherapy, characterized in that: Its structure includes, from bottom to top, a substrate, a graphene / GaAs buffer layer, an n-type semiconductor layer, an InGaAs / GaAs multi-quantum well light-emitting layer, a p-type semiconductor layer, and a GaAs contact layer. A GaAs / graphene periodic structure is deposited on a GaAs substrate (the substrate is not limited to GaAs, InP, germanium, or silicon) as a buffer layer, with 3-50 periods and an optical thickness of λ / 4. The multi-quantum well light-emitting layer includes a red multi-quantum well sublayer and a yellow multi-quantum well sublayer that are deposited and grown sequentially from bottom to top.

2. The red-yellow LED epitaxial structure for phototherapy according to claim 1, characterized in that: nGaAs is deposited on the GaAs / graphene buffer layer, with a thickness ranging from 100 to 1000 nm and a doping concentration of 1E16 to 1E22.

3. The LED epitaxial structure for phototherapy with red and yellow light according to claim 1, characterized in that: An InGaAs / GaAs quantum well layer is deposited on the nGaAs layer, which consists of 3nm thick InGaAs and 4nm thick GaAs, with a thickness ranging from 30 to 200nm and a doping concentration of 1E16 to 1E22.

4. The red-yellow LED epitaxial structure for phototherapy according to claim 1, characterized in that: A p-type AlGaAs is deposited on the InGaAs / GaAs quantum well layer as an electron blocking layer, with a thickness ranging from 30 to 200 nm and a doping concentration of 1E16 to 1E22.

5. The red and yellow LED epitaxial structure for phototherapy according to claim 1, characterized in that: A p-type GaAs contact layer is deposited on the p-type GaAs layer, with a doping concentration ranging from 1E18 to 1E22, p-type doping, and a thickness ranging from 30 to 200 nm.

6. A method for preparing a red-yellow light LED epitaxial structure for phototherapy, the method being the method for preparing a red-yellow light LED epitaxial structure for phototherapy according to any one of claims 1 to 5, characterized in that: The method comprises using MOCVD / MBE / PECVD equipment to deposit a GaAs / graphene periodic structure as a buffer layer on a GaAs substrate (the substrate is not limited to GaAs, InP, germanium, or silicon), with 3-50 periods and an optical thickness of λ / 4, which can be n-type doped or undoped, and a GaAs doping concentration of 0-1E22; using N2 / H2 to pretreat the surface of the substrate; heating the pretreated substrate to 500-1000°C; introducing arsine and a gallium source to grow GaAs; switching the carbon source gas to grow graphene in an environment of 500-1000°C; and repeating the process 3-50 times. Depositing nGaAs on the GaAs / graphene buffer layer; Depositing an InGaAs / GaAs quantum well layer on the nGaAs layer; Depositing p-type AlGaAs as an electron blocking layer on the InGaAs / GaAs quantum well layer; depositing a p-type GaAs layer on the p-type AlGaAs layer; depositing a p-type GaAs contact layer on the p-type GaAs layer; Remove from heat after cooling to room temperature.

7. A chip with an LED epitaxial structure for red and yellow light therapy, characterized in that: The LED epitaxial structure for phototherapy using red and yellow light and the preparation method thereof are used as described in any one of claims 1 to 5.

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