High-efficiency red light plant illumination light-emitting diode epitaxial wafer and manufacturing method thereof

Abstract

The invention relates to a high-efficiency red light plant illumination light-emitting diode epitaxial wafer and a manufacturing method thereof. The epitaxial wafer comprises a plurality of epitaxial layers, a superlattice current expansion layer is adopted to replace a traditional GaP current expansion layer, low-doped GaxIn1-xP layers and high-doped AlyGa1-yP layers grow alternately, the transverse expansion capacity of current is optimized, and forward voltage is reduced. According to the invention, through accurate adjustment of the doping concentration of each layer, lattice matching and superlattice structure design, the photon efficiency of the LED device is improved, the voltage loss is significantly reduced, and the luminous efficiency is improved. Experimental results show that compared with a traditional structure, the structure provided by the invention has lower forward voltage and higher PPE value, and has wide application prospect and industrialization value.

Description

Technical Field

[0001] This patent belongs to the field of light-emitting diode semiconductors, and specifically relates to a high-efficiency structured red light plant lighting light-emitting diode epitaxial wafer and its manufacturing method. Background Art

[0002] Horticultural lighting primarily optimizes plant growth and development by controlling light intensity, photoperiod, spectral distribution, and light uniformity. LEDs offer advantages such as high electro-optical conversion efficiency, adjustable light intensity and spectrum, compact size, and long lifespan. Furthermore, they are low-heat, cold light sources that can illuminate plants at close ranges, making them ideal for modern agricultural plant lighting and holding promising application prospects in agriculture and biology. Driven by factors such as the food crisis caused by frequent extreme weather events worldwide, the rapid development of the horticultural industry, including artificially illuminated plant factories, supplemental lighting for horticultural facilities, and home gardening, coupled with the greenhouse effect's attenuation of solar radiation, the LED horticultural lighting sector is experiencing rapid growth, with the market expected to expand further in the future. Since plants require red light for proper flowering and fruiting, optimizing the light efficiency of red LED horticultural lighting has become a key area of market research.

[0003] Photosynthetic photon efficiency (PPE) has a significant impact on plant growth and development. PPE (Photosynthetic Photon Efficacy) can regulate plant growth, promote bud growth and flower and fruit formation, improve yield and quality, shorten the growth period, extend shelf life, and enhance plant disease and stress resistance. Therefore, in modern large-scale cultivation, an increasing number of farmers and researchers are beginning to pay attention to and apply PPE. Improving the PPE of plant lighting products, thereby promoting faster plant growth and increasing crop yield and quality, has become a crucial indicator in the development of LEDs for plant lighting.

[0004] PPE refers to plant photon utility, which is one of the most important indicators in plant lighting. It is calculated by dividing the photon flux by the energy consumption. It is used to evaluate the nutritional value and photosynthetic energy utilization efficiency of plant lamps. To obtain a high PPE value, it is necessary to reduce energy consumption and increase luminous power. The conventional red light plant lighting LED epitaxial structure is as follows: Figure 1 This conventional structure has two prominent problems: On the one hand, it is difficult to achieve a sufficiently high carrier concentration due to the Mg doping of P-type GaP, resulting in a high forward voltage (VF) of the device, and greatly reducing the current expansion capability of the device, and the product's anti-static ability (ESD) and luminous efficiency are also reduced. On the other hand, because the band gap width of the P-type AlInP layer is approximately 2.36eV, while the band gap width of the P-type GaP layer is approximately 2.26eV, there is a large band gap difference between the two, and the resistance at the interface is very high, making it difficult to reduce the forward voltage of the device.

[0005] Figure 1 Figure 2 shows a schematic diagram of the epitaxial structure of a conventional red plant lighting LED. Traditional red LED epiwafers typically use a P-type GaP layer as the current spreading layer and window layer (as shown in the figure), with a P-type GaP ohmic contact layer grown on top. Because the GaP material is difficult to heavily dope due to the Mg compensation effect, and there is a large bandgap and lattice mismatch with the underlying P-type AlInP confinement layer, the conventional structure has a high forward voltage, which affects current spreading capability and photon extraction efficiency. Summary of the Invention

[0006] In order to solve the above-mentioned problems, the present invention provides a high-efficiency structured red light plant lighting light-emitting diode epitaxial wafer and a manufacturing method thereof.

[0007] The light emitting diode comprises a substrate and an N-type GaAs ohmic contact layer, an N-type AlGaInP roughening layer, an N-type AlGaInP current spreading layer, an N-type AlInP limiting layer and an active layer, a P-type AlInP limiting layer, a P ... current spreading layer, an N-type AlInP limiting layer and an active layer, a P-type GaAs ohmic contact layer, an N-type AlGaInP current spreading layer, an N-type AlInP current spreading layer, an N-type AlInP current spreading layer, an N-type AlInP current spreading layer, an N-type AlInP current spreading layer, an N-type AlInP current spreading layer, an N-type AlInP current spreading x In 1- x P / Al y Ga 1-y P superlattice expansion layer, P-type AlGaP ohmic contact layer. x In 1-x P / Al y Ga 1-y The epitaxial layer grown alternately on the P superlattice replaces the P-type GaP current expansion layer. On the one hand, by adjusting the composition of Ga and In to control the band gap of GaInP, the barrier difference between the P-type AlInP confinement layer and the P-type expansion layer is reduced, the resistance between the interfaces is reduced, and the presence of In suppresses the C content, resulting in a low doping concentration in this layer and reduced light absorption; on the other hand, by adding an appropriate amount of Al to GaP to increase the C doping concentration, the forward voltage of the product is reduced. And Ga x In 1-x P / Al y Ga 1-y The two materials P are grown alternately, and the high-doped and low-doped layers alternate to form a superlattice structure, which makes the lateral expansion of the current better and the light output power of the product higher.

[0008] The manufacturing method of the present invention uses Metal Organic Vapor Chemical Deposition (MOCVD), and the growth temperature of each layer in the reaction chamber is controlled between 700 and 750 °C. According to the growth requirements of different epitaxial layers, precursor gas sources such as trimethylgallium (TMGa), trimethylaluminum (TMAl), trimethylindium (TMIn), arsine (AsH3), and phosphine (PH3) are respectively selected for growth. The specific process steps are as follows:

[0009] First, a N-type GaAs buffer layer is grown on a GaAs substrate, and Si2H6 or SiH4 is introduced as a N-type doping source with a doping concentration of 1×10 18 ~3×10 18 carriers / cm 3 ; then a N-type GaInP etch stop layer is grown, and Si2H6 or SiH4 is introduced with a doping concentration of 1×10 18 ~3×10 18 carriers / cm 3 ; then a N-type GaAs ohmic contact layer is grown with a thickness of Si2H6 or SiH4 is introduced with a doping concentration > 5×10 18 carriers / cm 3 ; continue to grow a N-type (Al z Ga 1-z )InP roughening layer, where 0.30 < z < 0.60 and the thickness is Si2H6 or SiH4 is introduced with a doping concentration of 1×10 18 ~3×​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Then, a multi - quantum - well active layer is grown, where the quantum - well barrier material is AlGaInP with a thickness of The quantum - well well - layer material is AlGaInP with a thickness of The number of periods composed of barriers / wells is 8 - 12 pairs, and this active layer is undoped; then, an undoped P - type (Al n Ga 1-n )InP waveguide layer is grown, where 0.30 < n < 0.60 and the thickness is Subsequently, a P - type AlInP confinement layer is grown with a thickness of Bis(cyclopentadienyl)magnesium (Cp2Mg) is introduced as a P - type doping source with a doping concentration of 1×10 18 ~1.5×10 18 carriers / cm 3 ; continue to grow a P - type (Al a Ga 1-a ) b In 1-b P transition layer, where 0.15 < a < 0.25, 0.65 < b < 0.75, and the thickness is Cp2Mg is introduced with a doping concentration of 2×10 18 ~3×10 18 carriers / cm 3 ; then, grow a P - type Ga x In 1-x P / Al y Ga 1-y P composite current - spreading layer, that is, a superlattice structure of multiple alternating GaInP / AlGaP periods, and a total of 10 - 20 pairs of GaInP / AlGaP superlattice units are grown. Among them, in the Ga x In 1-x P layer, 0.05 ≤ x ≤ 0.3 (the value of x on the side close to the P - type AlInP confinement layer gradually decreases from high), and in the Al y Ga 1-y P layer, 0.03 ≤ y ≤ 0.2; the thickness of each layer of the two materials can be the same or different, but the single - layer thickness is controlled within range. This composite current - spreading layer is co - doped with P - type by introducing Cp2Mg. Among them, the doping concentration of the Ga x In 1-x P layer is 1×10 18 ~3×10 18 carriers / cm 3 , and the doping concentration of the Al y Ga 1-y P layer is 7×10 18 ~1×10 19 carriers / cm 3; Finally, grow a P-type AlGaP ohmic contact layer with a thickness of CBr4 or CCl4 is introduced as a P-type doping source with a doping concentration greater than 5×10 19 carriers / cm 3 The above steps complete the epitaxial growth and produce a high-efficiency red light plant lighting light-emitting diode epitaxial wafer.

[0010] The "high-efficiency red light plant lighting LED epitaxial wafer and its manufacturing method" provided by the present invention successfully overcomes the P-type doping bottleneck and interface resistance problems in the existing technology by introducing a GaInP / AlGaP superlattice current expansion layer into the red light LED epitaxial structure. While reducing the forward voltage of the device, it significantly improves key performance indicators such as PPE, and has important practical value and industrialization prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the epitaxial structure of a conventional red light emitting diode for plant lighting.

[0012] Figure 2 It is a schematic diagram of the epitaxial structure of the high-efficiency red light plant lighting light-emitting diode of the present invention.

[0013] in, Figure 1 The structures corresponding to the numbers and letters in the figure are as follows: 500 is a GaAs substrate, 501 is an N-type GaAs buffer layer, 100 is an N-type GaInP etching stop layer, 101 is an N-type GaAs ohmic contact layer, 102 is an N-type AlGaInP roughening layer, 103 is an N-type AlGaInP current spreading layer, 104 is an N-type AlInP confinement layer, 105 is an N-type AlGaInP waveguide layer, 106 is an active layer, 107 is a P-type AlGaInP waveguide layer, 108 is a P-type AlInP confinement layer, 109 is a P-type AlGaInP transition layer, and 110 is a P-type GaP current spreading layer. Figure 2 The structures corresponding to the numbers and letters are as follows: 600 is GaAs substrate, 601 is N-type GaAs buffer layer, 200 is N-type GaInP etching stop layer, 201 is N-type GaAs ohmic contact layer, 202 is N-type (Al z Ga 1-z )InP rough layer, 203 is N-type (Al w Ga 1-w )InP current spreading layer, 204 is N-type AlInP limiting layer, 205 is N-type (Al m Ga 1-m )InP waveguide layer, 206 is a multi-quantum well active layer, 207 is a P-type (Al n Ga 1-n)InP waveguide layer, 208 is a P-type AlInP confinement layer, 209 is a P-type (Al a Ga 1-a ) b In 1-b P transition layer, 210 is P-type Ga x In 1-x P / Al y Ga 1-y The P superlattice composite current spreading layer 211 is a P-type AlGaP ohmic contact layer. DETAILED DESCRIPTION

[0014] Figure 2 Figure 2 shows the layer structure of the epitaxial wafer for the high-efficiency red light-emitting diode for plant lighting according to the present invention. This structure comprises multiple epitaxial layers extending from a GaAs substrate 600 to a P-type AlGaP contact layer 210. Compared to conventional structures, the present invention adds a composite current spreading layer 209 composed of alternating GaInP / AlGaP layers between the P-type confinement layer 208 and the P-type contact layer 210. Figure 2 The structure shown is grown using MOCVD technology. Figure 2 The illustrated process provides a detailed description of the specific implementation method.

[0015] In this embodiment, MOCVD method is used to prepare the following on GaAs substrate: Figure 2 The LED epitaxial wafer structure shown in the figure. During the growth process, the reaction chamber temperature is controlled within the range of 700-750°C, and the corresponding metal organic source and hydride gas source (such as TMGa, TMAl, TMIn, AsH3, PH3, etc.) are selected according to the different layers. Specifically, the growth steps of each epitaxial wafer layer are as follows:

[0016] 1. N-type GaAs buffer layer 601: First, an N-type GaAs buffer layer is grown on a clean GaAs substrate 600. The doping source is silane (Si2H6 or SiH4) with a doping concentration of about 1×10 18 ~3×10 18 carriers / cm 3 , used to reduce substrate surface defects and provide a growth template for subsequent layers.

[0017] 2. N-type GaInP etching stop layer 200: A layer of N-type GaInP is grown on the buffer layer as an etching stop layer. Silane is added for N-type doping with a concentration of about 1×10 18 ~3×10 18 carriers / cm 3 This layer can be used as an etching protection layer during epitaxial wafer thinning or chip manufacturing in subsequent processes.

[0018] 3. N-type GaAs ohmic contact layer 201: Grow an N-type GaAs ohmic contact layer on the etch stop layer with a thickness of Si2H6 or SiH4 is introduced for heavy doping (concentration>5×10 18 carriers / cm 3 ), forming N-type current expansion and ohmic contact area, which helps to reduce the contact resistance of the device.

[0019] 4.N type (Al z Ga 1-z ) InP rough layer 202: N-type (Al z Ga 1-z )InP layer is used as a roughening layer for current spreading, with a thickness of The Al component z is between 0.30 and 0.60. This layer is doped with Si2H6 or SiH4 (concentration of about 1×10 18 ~3×10 18 carriers / cm 3 ). By introducing an appropriate amount of Al into the material, the energy band gap of the layer is increased, the absorption of luminescence is reduced, and a certain current expansion effect is provided.

[0020] 5.N type (Al w Ga 1-w )InP current spreading layer 203: Continue to grow N-type (Al w Ga 1-w )InP current spreading layer, thickness is The Al component w is between 0.10 and 0.50. The doping condition is N-type (Si2H6 or SiH4), with a concentration of about 1×10 18 ~3×10 18 carriers / cm 3 This thick current spreading layer further transports carriers horizontally across the entire chip area, providing uniform current distribution in the active area.

[0021] 6. N-type AlInP confinement layer 204: Grow an N-type AlInP confinement layer on the current spreading layer with a thickness of Si2H6 or SiH4 is added for N-type doping, with a concentration of about 1×10 18 ~2×10 18 carriers / cm 3 AlInP has a large band gap, which limits the distribution of carriers and light fields in the active region.

[0022] 7. Undoped (Al m Ga 1-m )InP waveguide layer 205: grown on the lower confinement layer (Alm Ga 1-m )InP waveguide layer, thickness The Al composition m is between 0.30 and 0.60. This layer is undoped. As the lower waveguide layer of the active region, it adjusts the optical field distribution of the active region mode while maintaining high optical transparency.

[0023] 8. Multi-quantum well active layer 206: A light-emitting active region is grown on the waveguide layer, which is a multi-quantum well structure. The active layer is composed of AlGaInP material and has multiple barrier / well cycles: the thickness of the quantum well barrier layer is about The thickness of the quantum well layer is about The barriers and wells form a total of 8 to 12 pairs. The entire multi-quantum well structure is an intrinsic layer, undoped. The multi-quantum well structure is designed to optimize luminous efficiency in the red wavelength band.

[0024] 9. Undoped P type (Al n Ga 1-n )InP waveguide layer 207: P-type (Al n Ga 1-n )InP waveguide layer, thickness The Al composition n is between 0.30 and 0.60. This layer is not actually doped (because in a P-type environment, the AlInP intrinsic layer will exhibit a weak P-type), and serves as the upper waveguide layer of the active region to confine the optical field and conduct the injected current.

[0025] 10. P-type AlInP confinement layer 208: Grow a P-type AlInP confinement layer (i.e., the upper confinement layer of the active region) on the upper waveguide layer with a thickness of Cp2Mg is introduced for P-type doping, with a concentration of about 1×10 18 ~1.5×10 18 carriers / cm 3 This layer acts as a confinement layer, which can block the diffusion of electrons to the P region. At the same time, its larger band gap helps to reduce the re-absorption of light emitted from the active region.

[0026] 11.P type (Al a Ga 1-a ) b In 1-b P transition layer 209: A thin P-type transition layer is grown between the P-type limiting layer and the subsequent current spreading layer. The thickness is Composition: (Al a Ga 1-a ) b In 1-b P, where Al component a is 0.15-0.25 and In component b is 0.65-0.75. The doping source is Cp2Mg with a concentration of about 2×10 18~3×10 18 carriers / cm 3 By inserting a transition layer between AlInP and GaInP / AlGaP superlattice current spreading layer, the energy band and lattice constant of the materials are gradually transitioned, the interface stress and energy band discontinuity are relieved, and a good transition interface is created for the growth of the superlattice current spreading layer.

[0027] 12.P type Ga x In 1-x P / Al y Ga 1-y P superlattice composite current spreading layer 210: A P-type GaInP / AlGaP alternating superlattice structure is grown on the transition layer as a composite current spreading layer. x In 1-x P and Al y Ga 1-y P layers are alternately composed of Ga x In 1-x The In content x of the P layer is in the range of 0.05 to 0.3, and the x value is higher on the side close to the transition layer and decreases layer by layer; y Ga 1-y The Al content y of the P layer is in the range of 0.03 to 0.2. The thickness of each layer is controlled at The thickness of the two materials can be selected to be equal or different according to the needs. The entire superlattice alternating structure is co-doped with Cp2Mg, in which the acceptor concentration of the GaInP sublayer is about 1×10 18 ~3×10 18 carriers / cm 3 , and the AlGaP sublayer can introduce a higher concentration of carbon (C) acceptors due to the addition of Al, with a concentration of about 7×10 18 ~1×10 19 carriers / cm 3 This high-low doping alternating superlattice structure improves the horizontal propagation capability of the P-type side current.

[0028] 13. P-type AlGaP ohmic contact layer 211: Finally, grow a P-type AlGaP ohmic contact layer on the composite current spreading layer with a thickness of The doping source uses carbon tetrabromide (CBr4) or carbon tetrachloride (CCl4) to introduce C acceptors, and the doping concentration is >5×10 19 carriers / cm 3 , to achieve the highest P-type carrier concentration. This ultra-thin heavily doped AlGaP layer forms a good ohmic contact with the metal electrode, further expanding the current. Due to the large bandgap and thin thickness of AlGaP, there is almost no absorption loss in the emitted red light.

[0029] Through the above growth steps, the Figure 2 The resulting epitaxial wafer structure contains a complete P / N junction structure, current spreading, and contact layers. The thickness, material, and doping design of each layer are optimized to improve the device's optoelectronic performance.

[0030] Compared with the existing technology, the present invention has the following four technical innovations in epitaxial structure design:

[0031] Suppress C content and reduce light absorption loss: using Ga x In 1-x P material replaces the traditional GaP as the P-type current spreading layer. x In 1-x In P materials, the introduction of In elements affects the amphoteric behavior of C impurities in the material and leads to hydrogen passivation of acceptor impurities, thus inhibiting the effective incorporation of C in the material. x In 1-x The doping concentration in the P layer is difficult to reach a very high level, which significantly reduces the absorption of light by this layer, thereby improving the light extraction efficiency of the device.

[0032] Energy band and lattice buffer design: In the original structure, there is a large difference in band gap and lattice constant between the P-type AlInP confinement layer and the P-type GaP current expansion layer, which leads to higher resistance and more defects at the interface. x In 1-x P transition / extension layer and gradually adjust the x value (for example, using a higher In content near the AlInP layer and gradually transitioning to a lower In content), effectively narrowing the energy band difference between layers, reducing the interface barrier and contact resistance, and significantly reducing the forward voltage of the device. At the same time, due to the Ga x In 1-x The lattice constant of P is between AlInP and GaP. The gradient composition makes the lattice between layers more matched, improves the quality of epitaxial growth, reduces interface defects, and further improves the luminous efficiency of the device.

[0033] Introduction of high doping capacity AlGaP layer: using Al y Ga 1-y Substituting P material for part of GaP can significantly increase the acceptor doping concentration of the P-type layer. y Ga 1-y In P materials, the presence of Al increases the intrinsic C acceptor concentration in the lattice, enabling the layer to achieve a higher acceptor doping level, with a doping concentration of about 7×10 18 ~1×1019 carriers / cm 3 The introduction of this highly doped P-type AlGaP layer effectively reduces the series impedance of the device, thereby helping to further reduce the forward voltage.

[0034] Alternating superlattice improves lateral current scalability: through Ga x In 1-x P(low doping) / Al y Ga 1-y The alternating growth of P (highly doped) superlattices forms a composite current spreading layer, enabling efficient lateral expansion of carriers on the P-type side. Compared to the original single-material GaP expansion layer, this structure, composed of periodic alternations of high and low doping materials, provides a more optimized lateral conduction path, significantly reducing current crowding and improving the uniformity of current distribution within the chip plane, thereby enhancing the device's luminous efficiency.

[0035] In summary, the use of Ga x In 1-x P / Al y Ga 1-y The P superlattice structure replaces the traditional GaP current expansion layer, which not only effectively suppresses carrier recombination loss and self-absorption of red light, thereby improving the light output efficiency of the LED, but also reduces the interlayer interface resistance and device forward voltage, significantly improving the PPE index of the red light plant lighting LED.

[0036] To verify the effectiveness of the structure of the present invention, the R&D team conducted comparative experiments. Table 1 shows the comparison of forward voltage (VF) and photon efficiency (PPE) for devices with conventional structures and epitaxial structures employing different GaInP / AlGaP superlattice parameters.

Claims

1. A high-efficiency red light plant lighting light-emitting diode epitaxial wafer, characterized in that: The epitaxial wafer includes: N-type GaAs buffer layer; N-type GaInP etch stop layer; N-type GaAs ohmic contact layer, thickness is Doping concentration greater than 5×1018 carriers / cm 3 ; N-type (Al z Ga 1-z )InP roughening layer, where 0.30<z<0.60, thickness is N-type (Al w Ga 1-w )InP current spreading layer, where 0.10<w<0.50, thickness is N-type AlInP confinement layer, thickness is Undoped N-type (Al m Ga 1-m )InP waveguide layer, where 0.30<c<0.60, thickness is The multi-quantum well active layer is composed of 8 to 12 pairs of AlGaInP barrier layers and AlGaInP well layers alternating with each other; Undoped P-type (Al n Ga 1-n )InP waveguide layer, where 0.30<n<0.60, thickness is P-type AlInP confinement layer, thickness is P-type (Al a Ga 1-a ) b In 1-b P transition layer, where 0.15<a<0.25, 0.65<b<0.75, thickness is P type Ga x In 1-x P / Al y Ga 1-y P superlattice composite current spreading layer, which is a superlattice structure composed of 10 to 20 pairs of GaInP and AlGaP layers grown alternately, where Ga_xIn 1-x 0.05≤x≤0.3 in P, 0.03≤y≤0.2 in AlyGa1-yP, and the thickness of each layer is P-type AlGaP ohmic contact layer, thickness is Doping concentration is greater than 5×10 19 carriers / cm 3 ; Wherein, the P-type Ga x In 1-x In the P / AlyGa1-yP superlattice composite current spreading layer: Ga x In 1-x The x value of the P layer gradually decreases on the side close to the P-type AlInP confinement layer; Ga x In 1-x The doping concentration of P is 1×10 18 ~3×10 18 carriers / cm 3 ; Al y Ga 1-y The doping concentration of P is 7×10 18 ~1×10 19 carriers / cm 3 .

2. The epitaxial wafer according to claim 1, wherein: The doping concentration of the N-type GaAs buffer layer is 1×10 18 ~3×10 18 carriers / cm 3 .

3. The epitaxial wafer according to claim 1, wherein: In the multi-quantum well active layer, the thickness of the AlGaInP barrier layer is The thickness of the AlGaInP potential well layer is 4. The epitaxial wafer according to claim 1, wherein: The P-type (Al a Ga 1-a ) b In 1-b The doping concentration of the P transition layer is 2×10 18 ~3×10 18 carriers / cm 3 .

5. The epitaxial wafer according to claim 1, wherein: The Ga x In 1-x In the P / AlyGa1-yP superlattice composite current spreading layer, Ga x In 1-x The thicknesses of P and AlyGa1-yP can be equal or different.

6. The epitaxial wafer according to claim 1, wherein: The superlattice structure is grown by metal organic vapor deposition (MOCVD) method, and the temperature of the reaction chamber is controlled between 700 and 750°C.

7. A method for manufacturing the epitaxial wafer according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: (1) Provide a GaAs substrate and grow an N-type GaAs buffer layer on it. The doping source is Si2H6 or SiH4 with a doping concentration of 1×10 18 ~3×10 18 carriers / cm 3 ; (2) N-type GaInP etching stop layer, N-type GaAs ohmic contact layer, N-type (Al z Ga 1-z )InP rough layer and N-type (Al w Ga 1-w )InP current spreading layer, all doped with N-type source, with a doping concentration of 1×10 18 ~3×10 18 carriers / cm 3 ; (3) Growth of N-type AlInP confinement layer and undoped (Al m Ga 1-m )InP waveguide layer; (4) growing a multi-quantum well active layer, including 8 to 12 pairs of AlGaInP barrier layers and AlGaInP well layers; (5) Growth of undoped P-type (Al n Ga 1-n )InP waveguide layer, and P-type AlInP confinement layer and P-type (Al a Ga 1-a ) b In 1-b P transition layer; (6) Using metal organic vapor deposition (MOCVD) to alternately grow Ga x In 1-x P layer and Al y Ga 1-y P layer, forming a superlattice composite current expansion layer of 10 to 20 periods, each layer is The growth temperature is controlled at 700-750°C, and the P-type doping source is Cp2Mg; (7) Finally, grow a P-type AlGaP ohmic contact layer, the doping source is CBr4 or CCl4, and the doping concentration is greater than 5×10 19 carriers / cm 3 .

8. The method according to claim 7, wherein: In step (6), the Ga x In 1-x The x value of the P layer gradually decreases from a high value on the side close to the transition layer in the superlattice growth direction to achieve band gap transition and lattice buffer.

9. The method according to claim 7, wherein: The reaction sources used in the MOCVD growth process include TMGa, TMAl, TMIn, AsH3 and PH3, and the growth temperature of all epitaxial layers is controlled within the range of 700-750°C.

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