CN111326614A - Method for improving luminous efficiency of outdoor lighting source - Google Patents

Abstract

The invention provides a method for improving the light efficiency of an outdoor lighting source, which comprises forming a semi-crystalline layer, an undoped layer, an N-type doped layer, an active layer and a P-type doped layer on a substrate in sequence; The layers include a periodically overlapping quantum well layer and a quantum barrier layer, the quantum well layer is an indium gallium nitride layer, and the quantum barrier layer is a gallium nitride layer, and after forming at least one of the quantum well layers, the indium source is passed into the indium source. Then, the carbon source is introduced, and the quantum barrier layer is formed after the carbon source is introduced. In the present invention, the indium source is passed into the quantum well layer, the indium treatment layer is formed on the surface of the indium gallium nitride, the carbon source is passed on the indium treatment layer, and the carbon source is decomposed at high temperature and contacts the indium treatment layer to form a carbon two-dimensional structure, The combination of the indium treatment layer and the carbon two-dimensional structure further increases the potential well depth of the quantum well layer, and at the same time improves the carrier concentration and mobility, thereby improving the internal quantum efficiency and improving the light efficiency of the light source.

Description

Methods for improving the light efficiency of outdoor lighting sources

technical field

The invention relates to the technical field of automotive lighting, in particular to a method for improving the light efficiency of an outdoor lighting light source.

Background technique

Building a smart city and promoting green lighting can achieve sustainable urban development. In recent years, driven by the government, the LED outdoor lighting industry has gained more room for development, especially in the field of road lighting and landscape lighting. After years of exploration and development of LED outdoor lighting, the technology in the application process has been continuously innovated and breakthroughs, the level has been continuously improved, the accumulation of quality has been completed, the price has dropped, and the market has continued to grow steadily.

Due to the huge potential of the LED outdoor lighting market, domestic and foreign manufacturers are rushing to enter, and homogeneous products emerge in an endless stream, resulting in uneven product quality and unstable performance, which has become a confusing point for the current LED industry pattern. Considering the special use conditions of outdoor products, outdoor LED professional lighting must pay more attention to the improvement of light efficiency and product quality.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a method for improving the luminous efficiency of an outdoor lighting source, which can effectively improve the luminous efficiency and performance of the outdoor lighting source.

The technical problem to be solved by this invention adopts the following technical solutions to realize:

A method for improving light efficiency of an outdoor lighting source, comprising providing a substrate, forming a semi-crystalline layer on the substrate, forming an undoped layer on the semi-crystalline layer, and forming N on the undoped layer type doped layer, an active layer is formed on the N-type doped layer, and a P-type doped layer is formed on the active layer; the active layer includes a periodically overlapping quantum well layer and a quantum barrier layer , the quantum well layer is an indium gallium nitride layer, and the quantum barrier layer is a gallium nitride layer. After forming at least one of the quantum well layers, the indium source is passed, the indium source is passed into the carbon source, and the carbon source is passed through to form a quantum barrier layer.

Optionally, after the quantum well layer is formed, the aluminum nitride layer is formed before the indium source is passed through.

Optionally, the formed aluminum nitride layer is located on one side of the N-type doped layer.

Optionally, the formed aluminum nitride layer is located on the quantum well layer closest to the N-type doped layer.

Optionally, after each quantum well layer is formed in the active layer, an indium source is passed, a carbon source is passed after the indium source is passed, and a quantum barrier layer is formed after passing the carbon source.

Optionally, the flow of indium source in the active layer gradually increases from the N-type doped layer side to the P-type doped layer side after each quantum well layer is formed.

Optionally, after each quantum well layer is formed in the active layer from the N-type doped layer side to the P-type doped layer side, the flow rate of the carbon source passed in gradually decreases.

Optionally, after the carbon source is introduced, the silicon source is also introduced.

Optionally, the time of passing the silicon source lasts until the end of the quantum epilayer growth.

Optionally, the flow rate of the silicon source is gradually reduced.

The beneficial effects of the present invention are as follows: the present invention forms an indium treatment layer on the surface of the indium gallium nitride by introducing an indium source after the quantum well layer is formed, and a carbon source is introduced into the indium treatment layer. Contact forms a carbon two-dimensional structure, and the combination of the indium treatment layer and the carbon two-dimensional structure further increases the potential well depth of the quantum well layer, and at the same time improves the carrier concentration and mobility, thereby improving the internal quantum efficiency and improving the light efficiency of the light source.

Description of drawings

Fig. 1 is the product structure schematic diagram that obtains according to the present invention;

2 to 4 are schematic diagrams of product structures obtained according to a preferred embodiment of the present invention.

Detailed ways

The method for improving the luminous efficiency of an outdoor lighting source provided by the present invention will be described in more detail below with reference to the accompanying drawings, in which the preferred embodiments of the present invention are shown. It should be understood that those skilled in the art can modify the present invention described herein and still achieve Advantageous effects of the present invention. Therefore, the following description should be construed as widely known to those skilled in the art and not as a limitation of the present invention.

The invention is described in more detail by way of example in the following paragraphs with reference to the accompanying drawings. The advantages and features of the present invention will become apparent from the following description and claims. It should be noted that, the accompanying drawings are all in a very simplified form and in inaccurate scales, and are only used to facilitate and clearly assist the purpose of explaining the embodiments of the present invention.

The core of the present invention is to provide a method for improving the light efficiency of an outdoor lighting source, including providing a substrate 1, forming a semi-crystalline layer 2 on the substrate 1, forming an undoped layer 3 on the semi-crystalline layer 2, and forming an undoped layer 3 on the semi-crystalline layer 2. An N-type doped layer 4 is formed on the impurity layer 3, an active layer 5 is formed on the N-type doped layer 4, and a P-type doped layer 6 is formed on the active layer 5; the active layer 5 includes periodically overlapping quantum The well layer 51 and the quantum barrier layer 52, the quantum well layer is an indium gallium nitride layer, and the quantum barrier layer is a gallium nitride layer. After forming at least one of the quantum well layers 51, the indium source is passed, and the carbon source is passed after the indium source is passed. After the carbon source is passed through, the quantum barrier layer 52 is formed, and the structure of the obtained product is shown in FIG. 1 .

The quantum barrier layer is a gallium nitride layer, and gallium nitride is a direct bandgap semiconductor material with a forbidden band width of 3.39eV at room temperature. The quantum well layer is an indium gallium nitride layer. The indium source is formed. As the indium content increases, the forbidden band width gradually decreases, and the depth of the potential well formed gradually deepens. The electrons and holes recombine in the quantum well layer, and the periodically overlapping quantum well layer and quantum barrier layer emit light. , the light-emitting quantum well layer is mainly concentrated on the side close to the P-type doping layer, which is mainly because the electron mobility is greater than the hole mobility, and it is more difficult to form P-type doping than N-type doping, resulting in a low hole concentration. According to the electron concentration, after forming the quantum well layer, the indium source is passed, and the indium treatment layer is formed on the surface of the indium gallium nitride, and the carbon source is passed on the indium treatment layer. On the one hand, the combination of the indium treatment layer and the carbon two-dimensional structure further increases the potential well depth of the quantum well layer, and at the same time improves the carrier concentration and mobility, thereby improving the internal quantum efficiency and improving the light efficiency of the light source.

In this embodiment, the material of the substrate 1 is sapphire, silicon carbide, silicon or gallium nitride.

The substrate material is an important factor in determining the performance indicators such as the color, brightness, and life of the light source. The surface roughness, thermal expansion coefficient, thermal conductivity coefficient, polarity of the substrate material, processing requirements of the surface, and whether the lattice matches the epitaxial material. The factors are closely related to the luminous efficiency and stability of the light source.

In this embodiment, the substrate 1 is a flat plate or a patterned substrate. The use of a patterned substrate can improve light scattering. The patterned substrate pattern is a triangular shape, a cone shape, a column shape or Arrays of other shapes can increase the light extraction efficiency of the light source to more than 60%, and at the same time, using a patterned substrate can control the extension direction of dislocations during the crystallization process, thereby effectively reducing the dislocation density.

Next, the semi-crystalline layer 2 is formed on the substrate 1 .

In this embodiment, the material of the semi-crystalline layer 2 is gallium nitride, aluminum nitride or aluminum gallium nitride, the temperature for forming the semi-crystalline layer 2 is 400° C. to 700° C., the pressure is 300 Torr to 700 Torr, and the thickness is 10 nm to 50 nm. .

The crystal state of the semi-crystalline layer is between single crystal and polycrystalline, and there is a serious lattice mismatch and thermal stress mismatch in heteroepitaxy (substrate material is different from gallium nitride material). By growing a layer of semi-crystalline The interlayer can effectively reduce the lattice mismatch and thermal stress mismatch between two different materials. In other embodiments, the semi-crystalline layer may be omitted when homoepitaxial.

Next, the undoped layer 3 is formed on the semi-crystalline layer 2 .

In this embodiment, the temperature for forming the undoped layer 3 is 900° C.˜1200° C., the pressure is 100 Torr˜500 Torr, and the thickness is 0.5 μm˜5 μm.

In this embodiment, the undoped layer 3 may include a 3D undoped layer grown in a three-dimensional mode and a 2D undoped layer grown in a two-dimensional mode, and the 3D undoped layer and the 2D undoped layer are formed sequentially On the semi-crystalline layer 2, the 3D undoped layer forms an island structure, and the 2D undoped layer fills the island structure to form a flat surface.

Next, an N-type doped layer 4 is formed on the undoped layer 3 .

In this embodiment, the N-type doped layer 4 can be formed by tetravalent silicon atoms replacing trivalent gallium atoms to form electrons. The temperature for forming the N-type doped layer 4 is 900° C. to 1200° C., the pressure is 100 Torr to 500 Torr, and the thickness is 4.5um. ~9um, the doping concentration is 2e18cm ^-3 ~6e20cm ^-3 .

In this example, silane was used as the silicon source.

Next, the active layer 5 is formed on the N-type doped layer 4 .

In this embodiment, the temperature for forming the active layer 5 is 700° C.˜900° C., the pressure is 100 Torr˜300 Torr, and the thickness is 25 nm˜320 nm.

In this embodiment, the formation of the active layer 5 includes a quantum well layer 51 and a quantum barrier layer 52 that are periodically stacked on the N-type doped layer 4 , and the active layer 5 is composed of 5 to 20 groups of periodically stacked quantum well layers 51 and 52 . The quantum barrier layer 52 is composed of the quantum well layer 51 having a thickness of 2.0 nm˜4.0 nm, and the quantum barrier layer 52 having a thickness of 3.0 nm˜12.0 nm.

In this embodiment, the quantum well layer 51 is formed by doping indium in the gallium nitride layer to form indium gallium nitride, and the quantum barrier layer 52 is a gallium nitride layer. Due to the high temperature, it is difficult to dope indium into the gallium nitride, so it is generally formed The temperature of the quantum well layer 51 is lower than the temperature at which the quantum barrier layer 52 is formed, and the temperature difference is about 60-160°C.

Under the action of external current, the electrons generated by the N-type doped layer 4 and the holes generated by the P-doped layer 6 recombinely emit light in the active layer 5, so the structure of the active layer has an important influence on the light emission of the light source.

In this embodiment, after forming at least one of the quantum well layers 51 , the indium source is connected, the carbon source is connected after the indium source, and the quantum barrier layer 52 is formed after the carbon source is connected.

The quantum barrier layer is a gallium nitride layer, and gallium nitride is a direct bandgap semiconductor material with a forbidden band width of 3.39eV at room temperature. The quantum well layer is an indium gallium nitride layer. The indium source is formed. As the indium content increases, the forbidden band width gradually decreases, and the depth of the potential well formed gradually deepens. The electrons and holes recombine in the quantum well layer, and the periodically overlapping quantum well layer and quantum barrier layer emit light. , the light-emitting quantum well layer is mainly concentrated on the side close to the P-type doping layer, which is mainly because the electron mobility is greater than the hole mobility, and it is more difficult to form P-type doping than N-type doping, resulting in a low hole concentration. According to the electron concentration, after forming the quantum well layer, the indium source is passed, and the indium treatment layer is formed on the surface of the indium gallium nitride, and the carbon source is passed on the indium treatment layer. On the one hand, the combination of the indium treatment layer and the carbon two-dimensional structure further increases the potential well depth of the quantum well layer, and at the same time improves the carrier concentration and mobility, thereby improving the internal quantum efficiency and improving the light efficiency of the light source.

In this embodiment, the indium source can be trimethyl indium, the flow rate of the indium source is 50-500 sccm, and the carbon source can be one or more of methane, ethane, acetylene, and propane. The flow rate of the incoming carbon source is 10-100 sccm.

In this embodiment, the carbon source may be directly passed in after the indium source is passed through, or the carbon source may be passed in after a period of time after the indium source is passed through, and the interval may be 10s˜2min.

In a specific embodiment, the indium source flow rate is 75sccm, 125sccm, 175sccm, 225sccm, 275sccm, 325sccm, 375sccm, 425sccm or 475sccm, or 50-100sccm, 100-150sccm, 150-200sccm, 200-250sccm, 250-sccm Any value within any interval of 300sccm, 300-350sccm, 350-400sccm, 400-450sccm, and 450-500sccm.

In a specific embodiment, the flow rate of the incoming carbon source is 15sccm, 25sccm, 35sccm, 45sccm, 55sccm, 65sccm, 75sccm, 85sccm or 95sccm, or 10-20sccm, 20-30sccm, 30-40sccm, 40-50sccm, 50- Any value within any interval of 60sccm, 60-70sccm, 70-80sccm, 80-90sccm, and 90-100sccm.

In a specific embodiment, after the indium source is introduced, the carbon source is introduced after an interval of 10s, 20s, 30s, 40s, 50s, 1min, 1min10s, 1min20s, 1min30s, 1min40s, 1min50 or 2min.

In this embodiment, the indium source is supplied to maintain the temperature and pressure equal to the temperature and pressure for forming the quantum well layer 51 , and the carbon source is supplied to maintain the temperature and pressure equal to the temperature and pressure for forming the quantum epilayer 52 .

Referring to FIG. 2 , preferably in this embodiment, after the quantum well layer 51 is formed, the aluminum nitride layer 50 is formed before the indium source is passed through.

An indium source is passed on the quantum well layer to form an indium treatment layer. The indium in the indium treatment layer will penetrate into the indium gallium nitride layer, so that the indium distribution on the surface of the indium treatment layer is uneven and the flatness is poor. At this time, it is difficult to pass the carbon source. A high-quality carbon two-dimensional structure is obtained. For this reason, forming an aluminum nitride layer on the quantum well layer before passing in the indium source can provide a flat surface and prevent the indium source from penetrating into the indium gallium nitride layer, thereby obtaining high-quality carbon dioxide. dimensional structure; the forbidden band width of aluminum nitride is 6.28eV, which is much higher than that of gallium nitride, and has a blocking effect on electrons. After the quantum well layer is formed, an aluminum nitride layer is formed before the indium source is passed through, and the aluminum nitride layer will block the N-type The electrons generated in the doped layer transition to the active layer, which is favorable for the current to expand at the contact interface between the N-type doped layer and the active layer, and is especially suitable for large current injection.

In this embodiment, the aluminum nitride layer 50 is obtained by reacting trimethyl aluminum with ammonia gas, the temperature for forming the aluminum nitride layer 50 is 700° C. to 1500° C., the pressure is 100 Torr to 300 Torr, and the thickness of the aluminum nitride layer 50 is 2～1500° C. 12nm.

In a specific embodiment, the thickness of the aluminum nitride layer 50 is 2.5 nm, 3.5 nm, 4.5 nm, 5.5 nm, 6.5 nm, 7.5 nm, 8.5 nm, 9.5 nm, 10.5 nm or 11.5 nm, or 2˜3 nm, 3 nm Any value within any range of ~4nm, 4~5nm, 5~6nm, 6~7nm, 7~8nm, 8~9nm, 9~10nm, 10~11nm, 11~12nm.

Referring to FIG. 3 , preferably, the formed aluminum nitride layer 50 is located on the side of the N-type doped layer 4 .

Referring to FIG. 4 , as the best preference in this embodiment, the formed aluminum nitride layer 50 is located on the quantum well layer 51 that is closest to the N-type doped layer 4 .

At this time, the least electron transitions into the active layer to achieve the best current expansion effect. At the same time, it can ensure that the active layer has sufficient carrier concentration and mobility after sufficient indium treatment and carbon treatment, and the light efficiency of the light source is the highest. .

Preferably in this embodiment, after each quantum well layer 51 is formed in the active layer 5, an indium source is supplied, a carbon source is supplied after the indium source is supplied, and a quantum barrier layer 52 is formed after the carbon source is supplied.

Preferably in this embodiment, the indium source flow in the active layer 5 increases gradually from the N-type doped layer 4 side to the P-type doped layer 6 side after each quantum well layer 51 is formed.

In one embodiment, the flow rate of the indium source passed into the latter quantum well layer is the flow rate of the indium source passed into the previous quantum well layer increased by 10 sccm, 20 sccm, 30 sccm, 40 sccm, 50 sccm, 100 sccm, 200 sccm, or 10-200 sccm. any value within.

As a further preference in this embodiment, the flow rate of the indium source passed after each quantum well layer 51 is gradually increased.

In this embodiment, the flow rate of the indium source is set to an initial value in the range of 50-500 sccm, and then gradually increases at a fixed flow rate in the range of 1-20 sccm/min.

In a specific embodiment, the initial flow rate of the indium source is 50sccm, and then the flow rate is 1sccm/min, 2sccm/min, 3sccm/min, 4sccm/min, 5sccm/min, 6sccm/min, 7sccm/min, 8sccm/min, 9sccm /min, 10sccm/min, 11sccm/min, 12sccm/min, 13sccm/min, 14sccm/min, 15sccm/min, 16sccm/min, 17sccm/min, 18sccm/min, 19sccm/min or 20sccm/min any fixed flow rate gradually increase.

In another specific embodiment, the initial flow rate of the indium source is 100sccm, and then the flow rate of the indium source is 1sccm/min, 2sccm/min, 3sccm/min, 4sccm/min, 5sccm/min, 6sccm/min, 7sccm/min, 8sccm/min, 9sccm/min, 10sccm/min, 11sccm/min, 12sccm/min, 13sccm/min, 14sccm/min, 15sccm/min, 16sccm/min, 17sccm/min, 18sccm/min, 19sccm/min or 20sccm/min fixed The flow gradually increased.

In other embodiments, the initial flow rate of the indium source is any value in the range of 50-500 sccm, and then gradually increases at a fixed flow rate in the range of 1-20 sccm/min.

Preferably in this embodiment, the flow rate of the carbon source in the active layer 5 from the side of the N-type doped layer 4 to the side of the P-type doped layer 6 gradually decreases after each quantum well layer 51 is formed.

In one embodiment, the flow rate of the carbon source passed into the latter quantum well layer is the flow rate of the carbon source passed into the previous quantum well layer that is successively reduced by 10 sccm, 20 sccm, 30 sccm, 40 sccm, 50 sccm or any within the interval of 10-50 sccm. a value.

As a further preference in this embodiment, the flow rate of the carbon source passed after each quantum well layer 51 is gradually reduced.

In this embodiment, the flow rate of the carbon source is set to an initial value within the range of 10-100 sccm, and then gradually decreases at a fixed flow rate within the range of 1-10 sccm/min.

In a specific embodiment, the initial flow rate of the carbon source is 100sccm, and then the flow rate is 1sccm/min, 2sccm/min, 3sccm/min, 4sccm/min, 5sccm/min, 6sccm/min, 7sccm/min, 8sccm/min, 9sccm Either a fixed flow rate of /min or 10sccm/min is gradually reduced.

In another specific embodiment, the initial flow rate of the carbon source is 50sccm, and then the flow rate is 1sccm/min, 2sccm/min, 3sccm/min, 4sccm/min, 5sccm/min, 6sccm/min, 7sccm/min, 8sccm/min, Either a fixed flow rate of 9sccm/min or 10sccm/min is gradually reduced.

In other embodiments, the initial flow rate of the carbon source is any value in the range of 10-100 sccm, and then gradually decreases at a fixed flow rate in the range of 1-10 sccm/min.

Preferably in this embodiment, after the carbon source is introduced, the silicon source is also introduced.

After the carbon source is introduced to form a carbon two-dimensional structure, some of the excess carbon atoms are located on the two-dimensional structure. When the silicon source is introduced, the silicon atoms are combined with the excess carbon atoms to form silicon carbide, which can effectively prevent excess carbon from causing carbon pollution and carbonization. The lattice mismatch between silicon and gallium nitride is small, and the two have good fusion properties. Silicon carbide has good electrical and thermal conductivity, which helps to improve the electrical properties of the active layer and heat dissipation during light emission.

In this embodiment, the silicon source may be silane, and the flow rate of the silicon source is 2-20 sccm.

In a specific embodiment, the flow rate of the incoming silicon source is 3sccm, 5sccm, 7sccm, 9sccm, 11sccm, 13sccm, 15sccm, 17sccm or 19sccm, or 2-4sccm, 4-6sccm, 6-8sccm, 8-10sccm, 10- Any value within any interval of 12sccm, 12-14sccm, 14-16sccm, 16-18sccm, and 18-20sccm.

Preferably, in this embodiment, the silicon source is supplied for a period of time until the growth of the quantum epilayer 52 ends.

As a further preference in this embodiment, the flow rate of the silicon source gradually decreases.

In this embodiment, the flow rate of the silicon source is set to an initial value within the range of 2-20 sccm, and then gradually decreases at a fixed flow rate within the range of 0.1-1 sccm/min.

In a specific embodiment, the initial flow rate of the silicon source is 20sccm, and then the flow rate is 0.1sccm/min, 0.2sccm/min, 0.3sccm/min, 0.4sccm/min, 0.5sccm/min, 0.6sccm/min, 0.7sccm/min Any fixed flow rate of min, 0.8sccm/min, 0.9sccm/min or 1sccm/min is gradually reduced.

In another specific embodiment, the initial flow rate of the silicon source is 10sccm, and then the flow rate is 0.1sccm/min, 0.2sccm/min, 0.3sccm/min, 0.4sccm/min, 0.5sccm/min, 0.6sccm/min, 0.7sccm /min, 0.8sccm/min, 0.9sccm/min or 1sccm/min any fixed flow rate gradually decreased.

In other embodiments, the initial flow rate of the silicon source is any value in the range of 2-20 sccm, and then gradually decreases at a fixed flow rate in the range of 0.1-1 sccm/min.

As the best preference in this embodiment, the flow rate of the silicon source is gradually reduced to 0.

Finally, a P-type doped layer 6 is formed on the active layer 5 .

In this embodiment, the P-type doped layer 6 may be formed by replacing trivalent gallium atoms with divalent magnesium atoms to form holes.

In this embodiment, the temperature for forming the P-type doped layer 6 is 800° C.˜1200° C., the pressure is 100 Torr˜500 Torr, the thickness is 50 nm˜300 nm, and the doping concentration is 5e18 cm ⁻³ ˜5e20 cm ⁻³ .

In this example, magnesium bisocene was used as the magnesium source.

In this embodiment, etching is performed on a part of the surface area of the P-type doped layer 6 to the N-type doped layer 4 and the N-type doped layer 4 is exposed. The impurity layer 6 is provided with a positive electrode, and the positive electrode, the negative electrode and the power supply are connected to emit light.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (10)

1. The method for improving the luminous efficiency of the outdoor lighting source is characterized by comprising the steps of providing a substrate, forming a semi-crystalline layer on the substrate, forming an undoped layer on the semi-crystalline layer, forming an N-type doped layer on the undoped layer, forming an active layer on the N-type doped layer, and forming a P-type doped layer on the active layer; the active layer comprises periodically overlapped quantum well layers and quantum barrier layers, the quantum well layers are indium gallium nitride layers, the quantum barrier layers are gallium nitride layers, an indium source is introduced after at least one of the quantum well layers is formed, a carbon source is introduced after the indium source is introduced, and the quantum barrier layers are formed after the carbon source is introduced.

2. An outdoor lighting source light effect improving method according to claim 1, wherein after the quantum well layer is formed, an aluminum nitride layer is formed before the indium source is introduced.

3. The method of claim 2, wherein the aluminum nitride layer is formed on the N-doped layer.

4. The method of claim 3, wherein the aluminum nitride layer is formed on the quantum well layer closest to the N-doped layer.

5. The method for improving the luminous efficiency of the outdoor lighting source according to claim 1, wherein an indium source is introduced after each quantum well layer is formed in the active layer, a carbon source is introduced after the indium source is introduced, and a quantum barrier layer is formed after the carbon source is introduced.

6. The method for improving the luminous efficiency of the outdoor lighting source as claimed in claim 5, wherein the flow of the indium source introduced into the active layer from the side of the N-type doping layer to the side of the P-type doping layer after each quantum well layer is formed is gradually increased.

7. The method for improving the luminous efficiency of the outdoor lighting source according to claim 6, wherein the flow of the carbon source introduced into the active layer from the side of the N-type doping layer to the side of the P-type doping layer after each quantum well layer is formed is gradually reduced.

8. The method as claimed in any one of claims 1 to 7, further comprising introducing a silicon source after the carbon source is introduced.

9. The method according to claim 8, wherein the silicon source is introduced for a time period until the growth of the quantum epitaxial layer is completed.

10. The method of claim 9 wherein the flow of the silicon source is gradually decreased.

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