Light-emitting diode epitaxial wafer for improving internal quantum efficiency and preparation method thereof

Abstract

The present disclosure discloses a light-emitting diode epitaxial wafer for improving internal quantum efficiency and a preparation method thereof, belonging to the field of light-emitting diode fabrication. The light-emitting diode epitaxial wafer for improving internal quantum efficiency includes a substrate and an n-type composite layer, a multi-quantum well layer, a p-type GaN layer, and a p-type contact layer sequentially stacked on the substrate. The n-type composite layer includes a gallium aluminum nitride layer, a first gallium nitride layer, a first silicon-doped gallium nitride layer, a second silicon-doped gallium nitride layer, and a silicon-doped aluminum nitride layer sequentially stacked. The doping concentration of silicon in the first silicon-doped gallium nitride layer is less than that in the second silicon-doped gallium nitride layer, and the doping concentration of silicon in the silicon-doped aluminum nitride layer is lower than that in the first silicon-doped gallium nitride layer. It can improve the internal quantum efficiency of the light-emitting diode to improve the light extraction efficiency of the light-emitting diode.

Description

Technical Field

[0001] The present disclosure relates to the field of light-emitting diode fabrication, and particularly to a light-emitting diode epitaxial wafer for improving internal quantum efficiency and a method for preparing the same. Background Art

[0002] A light-emitting diode is a semiconductor electronic component that can emit light. As an efficient, environmentally friendly, and green new solid-state lighting source, it is being rapidly and widely applied, such as traffic signal lights, interior and exterior automotive lights, urban landscape lighting, mobile phone backlights, etc. Improving the light-emitting efficiency of chips is an ongoing goal of light-emitting diodes.

[0003] In related technologies, the epitaxial wafer of a light-emitting diode generally includes a substrate and an n-type GaN layer, a multi-quantum well layer, a p-type GaN layer, and a p-type contact layer of gallium nitride material sequentially grown on the substrate. In related technologies, the multi-quantum well layer generally includes alternately stacked InGaN well layers and GaN barrier layers.

[0004] Since the drift rate of electrons in highly doped Si n-GaN is much greater than the drift rate of holes in the p-region, the injection rate of electrons in the n-region is better than that of holes in the p-region under the working voltage, resulting in the position of recombination luminescence in the multi-quantum well layer being concentrated on the superlattice side near the p-layer. This to a certain extent limits the light extraction efficiency of the multi-quantum well layer because in the traditional N-layer structure, AlGaN will generate stress on the GaN layer with higher or lower doping, increasing the influence of the polarization field on the front well behind. Under the working voltage of the applied electric field, obvious electron backflow phenomenon still occurs in the N-region, which will also affect the effective recombination of carriers in the active region macroscopically, reducing the internal quantum efficiency of the material and affecting the light extraction efficiency of the light-emitting device itself. Summary of the Invention

[0005] Embodiments of the present disclosure provide a light-emitting diode epitaxial wafer for improving internal quantum efficiency and a method for preparing the same, which can improve the internal quantum efficiency of the light-emitting diode to improve the light extraction efficiency of the light-emitting diode. The technical solution is as follows:

[0006] Embodiments of the present disclosure provide a light-emitting diode epitaxial wafer for improving internal quantum efficiency. The light-emitting diode epitaxial wafer for improving internal quantum efficiency includes a substrate and an n-type composite layer, a multi-quantum well layer, a p-type GaN layer, and a p-type contact layer sequentially stacked on the substrate. The n-type composite layer includes a gallium aluminum nitride layer, a first gallium nitride layer, a first silicon-doped gallium nitride layer, a second silicon-doped gallium nitride layer, and a silicon-doped gallium aluminum layer sequentially stacked. The doping concentration of silicon in the first silicon-doped gallium nitride layer is less than the doping concentration of silicon in the second silicon-doped gallium nitride layer, and the doping concentration of silicon in the silicon-doped gallium aluminum layer is lower than the doping concentration of silicon in the first silicon-doped gallium nitride layer.

[0007] Optionally, the ratio of the thickness of the gallium aluminum nitride layer, the thickness of the silicon-doped aluminum nitride layer, and the thickness of the n-type composite layer is 1:5 to 1:15, and the ratio of the thickness of the first silicon-doped gallium nitride layer, the thickness of the second silicon-doped gallium nitride layer, and the thickness of the n-type composite layer is 1:80 to 1:150.

[0008] Optionally, the thicknesses of the gallium aluminum nitride layer, the first gallium nitride layer, the first silicon-doped gallium nitride layer, the second silicon-doped gallium nitride layer, and the silicon-doped aluminum nitride layer are all 1 to 3 microns.

[0009] Optionally, the thickness of the first silicon-doped gallium nitride layer is less than the thickness of the second silicon-doped gallium nitride layer.

[0010] Optionally, the light-emitting diode epitaxial wafer for improving the internal quantum efficiency further includes an AlN nucleation layer and a GaN planarization layer. The AlN nucleation layer and the GaN planarization layer are stacked in sequence and are both located between the substrate and the n-type composite layer. The substrate has a plurality of grooves spaced apart from each other. The AlN nucleation layer includes a plurality of AlN filling layers corresponding to the grooves one by one. Each AlN filling layer is located in one of the grooves and the height of the AlN filling layer is lower than the depth of the groove. The GaN planarization layer covers the surface of the AlN nucleation layer and the surface of the substrate.

[0011] Optionally, the ratio of the height of the AlN nucleation layer to the depth of the groove is 1:50 to 1:1000.

[0012] Optionally, the thickness of the AlN nucleation layer is 15 to 2000 nm, and the thickness of the GaN planarization layer is 1 to 5 μm.

[0013] The embodiments of the present disclosure provide a method for preparing a light-emitting diode epitaxial wafer for improving the internal quantum efficiency. The preparation method includes:

[0014] Providing a substrate;

[0015] Growing an n-type composite layer, a multi-quantum well layer, a p-type GaN layer, and a p-type contact layer on the substrate in sequence. The n-type composite layer includes a gallium aluminum nitride layer, a first gallium nitride layer, a first silicon-doped gallium nitride layer, a second silicon-doped gallium nitride layer, and a silicon-doped aluminum nitride layer stacked in sequence. The doping concentration of silicon in the first silicon-doped gallium nitride layer is less than the doping concentration of silicon in the second silicon-doped gallium nitride layer, and the doping concentration of silicon in the silicon-doped aluminum nitride layer is lower than the doping concentration of silicon in the first silicon-doped gallium nitride layer.

[0016] Optionally, the first silicon-doped gallium nitride layer is grown in an atmosphere environment of hydrogen and ammonia, and the volume ratio of hydrogen to ammonia in the atmosphere environment of the first silicon-doped gallium nitride layer is 1.5:1 to 2:1.

[0017] Optionally, the growth rotation speed of the n-type composite layer is 500 - 800 rpm.

[0018] The beneficial effects brought by the technical solutions provided by the embodiments of the present disclosure are as follows:

[0019] In a light-emitting diode epitaxial wafer, the n-type composite layer includes a gallium aluminum nitride layer, a first gallium nitride layer, a first silicon-doped gallium nitride layer, a second silicon-doped gallium nitride layer, and a silicon-doped aluminum nitride layer stacked in sequence. The gallium aluminum nitride layer can block the flow of electrons near the multi-quantum well layer side towards the substrate or the structure below the n-type composite layer, avoiding electron backflow. While the silicon-doped aluminum nitride layer can avoid electron backflow, and due to doping with a certain amount of silicon element, the resistance to electrons is not too large, which can reduce electron backflow and play a certain role in current spreading, being beneficial to improving the light-emitting efficiency of the light-emitting diode and at the same time improving the light extraction uniformity of the light-emitting diode. The first gallium nitride layer can play a good transition role, ensuring better quality of the n-type composite layer, and can also block electron backflow to a certain extent, reducing the possibility of current breakdown. The first silicon-doped gallium nitride layer and the second silicon-doped gallium nitride layer can stably provide electrons. The doping concentration of silicon in the first silicon-doped gallium nitride layer is less than that in the second silicon-doped gallium nitride layer, and the doping concentration of silicon in the silicon-doped aluminum nitride layer is lower than that in the first silicon-doped gallium nitride layer, which can ensure that there are sufficient electrons in the part close to the multi-quantum well layer, promoting the flow of electrons towards the multi-quantum well layer. At the same time, there are also some electrons on the side of the n-type composite layer far from the multi-quantum well layer, which can make it easier for electrons to flow towards the multi-quantum well layer with almost no electrons, improving the uniformity and quantity of electrons entering the multi-quantum well layer, and the internal quantum efficiency of the light-emitting diode can be improved, and the light extraction uniformity and light extraction efficiency of the light-emitting diode can be improved. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 is a schematic structural diagram of a light-emitting diode epitaxial wafer for improving the internal quantum efficiency provided by the embodiments of the present disclosure;

[0022] Figure 2 is a schematic structural diagram of another light-emitting diode epitaxial wafer for improving the internal quantum efficiency provided by the embodiments of the present disclosure;

[0023] Figure 3 is a flowchart of a preparation method for a light-emitting diode epitaxial wafer for improving the internal quantum efficiency provided by the embodiments of the present disclosure;

[0024] Figure 4 It is a flowchart of another method for preparing a light-emitting diode epitaxial wafer with improved internal quantum efficiency provided by an embodiment of the present disclosure. Detailed implementation manners

[0025] To make the objectives, technical solutions and advantages of the present disclosure more clear, the following will further describe in detail the embodiments of the present disclosure with reference to the accompanying drawings.

[0026] Figure 1 It is a schematic structural diagram of a light-emitting diode epitaxial wafer with improved internal quantum efficiency provided by an embodiment of the present disclosure. Referring to Figure 1 it can be seen that the embodiment of the present disclosure provides a light-emitting diode epitaxial wafer with improved internal quantum efficiency. The light-emitting diode epitaxial wafer with improved internal quantum efficiency includes a substrate 1, and an n-type composite layer 2, a multi-quantum well layer 3, a p-type GaN layer 4, and a p-type contact layer 5 that are sequentially stacked on the substrate 1. The n-type composite layer 2 includes a gallium aluminum nitride layer 21, a first gallium nitride layer 22, a first silicon-doped gallium nitride layer 23, a second silicon-doped gallium nitride layer 24, and a silicon-doped aluminum nitride layer 25 that are sequentially stacked. The doping concentration of silicon in the first silicon-doped gallium nitride layer 23 is less than the doping concentration of silicon in the second silicon-doped gallium nitride layer 24, and the doping concentration of silicon in the silicon-doped aluminum nitride layer 25 is lower than the doping concentration of silicon in the first silicon-doped gallium nitride layer 23.

[0027] In the light-emitting diode epitaxial wafer, the n-type composite layer 2 includes a gallium aluminum nitride layer 21, a first gallium nitride layer 22, a first silicon-doped gallium nitride layer 23, a second silicon-doped gallium nitride layer 24, and a silicon-doped aluminum nitride layer 25 that are stacked in sequence. The gallium aluminum nitride layer 21 can block the flow of electrons on the side close to the multi-quantum well layer 3 towards the substrate 1 or the structure below the n-type composite layer 2, avoiding electron backflow. The silicon-doped aluminum nitride layer 25 can avoid electron backflow. At the same time, due to the doping of a certain amount of silicon element, the resistance to electrons is not too large, which can reduce electron backflow and play a certain role in current spreading, which is beneficial to improving the light-emitting efficiency of the light-emitting diode and the light extraction uniformity of the light-emitting diode. The first gallium nitride layer 22 can play a good transition role, ensuring that the quality of the n-type composite layer 2 is good, and can also block electron backflow to a certain extent, reducing the possibility of current breakdown. The first silicon-doped gallium nitride layer 23 and the second silicon-doped gallium nitride layer 24 can stably provide electrons. The doping concentration of silicon in the first silicon-doped gallium nitride layer 23 is less than the doping concentration of silicon in the second silicon-doped gallium nitride layer 24, and the doping concentration of silicon in the silicon-doped aluminum nitride layer 25 is lower than the doping concentration of silicon in the first silicon-doped gallium nitride layer 23, which can ensure that there are sufficient electrons in the part close to the multi-quantum well layer 3, promoting the flow of electrons towards the multi-quantum well layer 3. At the same time, there are also a part of electrons on the side of the n-type composite layer 2 far from the multi-quantum well layer 3, which can make it easier for electrons to flow towards the multi-quantum well layer 3 with almost no electrons, improving the uniformity and quantity of electrons entering the multi-quantum well layer 3, and the internal quantum efficiency of the light-emitting diode can be improved, and the light extraction uniformity and light extraction efficiency of the light-emitting diode can be improved.

[0028] Optionally, the thickness of the n-type composite layer 2 is 1 - 3 μm.

[0029] When the thickness of the n-type composite layer 2 is within the above range, it can ensure that the obtained n-type composite layer 2 has good quality and can also ensure the stable light emission of the light-emitting diode.

[0030] Optionally, the ratios of the thicknesses of the gallium aluminum nitride layer 21, the silicon-doped aluminum nitride layer 25, and the n-type composite layer 2 are all 1:5 - 1:15, and the ratios of the thicknesses of the first silicon-doped gallium nitride layer 23, the second silicon-doped gallium nitride layer 24, and the n-type composite layer 2 are all 1:80 - 1:150.

[0031] When the ratios of the thicknesses of the layers included in the n-type composite layer 2 to the overall thickness of the n-type composite layer 2 are within the above range, it can ensure that the n-type composite layer 2 can stably provide electrons, and the obtained n-type composite layer 2 has good quality, which can ensure the effective improvement of the light extraction efficiency of the light-emitting diode.

[0032] Exemplarily, the thicknesses of the gallium aluminum nitride layer 21, the first gallium nitride layer 22, the first silicon-doped gallium nitride layer 23, the second silicon-doped gallium nitride layer 24, and the silicon-doped aluminum nitride layer 25 are all 1 - 3 microns.

[0033] When the thicknesses of the layers in the n-type composite layer 2 are all within the above ranges, it can ensure that the n-type composite layer 2 plays a role in regulating electrons, while effectively reducing the possible light absorption problem of the n-type composite layer 2 and improving the light extraction efficiency of the obtained light-emitting diode.

[0034] Optionally, the thickness of the first silicon-doped gallium nitride layer 23 is less than the thickness of the second silicon-doped gallium nitride layer 24.

[0035] When the thickness of the first silicon-doped gallium nitride layer 23 is less than the thickness of the second silicon-doped gallium nitride layer 24, it can ensure the stable supply of electrons without excessively increasing the manufacturing cost of the n-type composite layer 2.

[0036] Optionally, the doping concentration of silicon in the second silicon-doped gallium nitride layer 24 is 10 18 cm -3 ~10 19 cm -3 , and the doping concentration of silicon in the first silicon-doped gallium nitride layer 23 is 10 17 cm -3 ~10 18 cm -3 。 This can ensure the quality of the n-type composite layer 2 while ensuring the role of the n-type composite layer 2 in regulating the electron concentration.

[0037] Exemplarily, the component of Al in the aluminum gallium nitride layer 21 is 0.5 to 0.8, and the component of Al in the silicon-doped aluminum nitride layer is 0.1 to 0.2.

[0038] When the ranges of the components of Al in the aluminum gallium nitride layer 21 and the silicon-doped aluminum nitride layer are respectively within the above ranges, it can effectively improve the light extraction efficiency of the finally obtained light-emitting diode.

[0039] Figure 2 is a schematic structural diagram of another light-emitting diode epitaxial wafer for improving the internal quantum efficiency provided by an embodiment of the present disclosure. Referring to Figure 2 it can be seen that the embodiment of the present disclosure provides a light-emitting diode epitaxial wafer for improving the internal quantum efficiency. The light-emitting diode epitaxial wafer for improving the internal quantum efficiency includes an AlN nucleation layer 6, a GaN planarization layer, an n-type composite layer 2, a multi-quantum well layer 3, an AlGaN electron blocking layer 8, a p-type GaN layer 4, and a p-type contact layer 5 stacked in sequence.

[0040] It should be noted that Figure 2 the n-type composite layer 2 shown in Figure 1 has the same structure as the n-type composite layer 2 shown in

[0041] and will not be described in detail here.

[0042] Exemplarily, the light-emitting diode epitaxial wafer for improving the internal quantum efficiency further includes an AlN nucleation layer 6 and a GaN planarization layer. The AlN nucleation layer 6 and the GaN planarization layer are stacked in sequence and are both located between the substrate 1 and the n-type composite layer 2. The substrate 1 has a plurality of grooves 11 spaced from each other. The AlN nucleation layer 6 includes a plurality of AlN filling layers 61 corresponding to the grooves 11 one by one. Each AlN filling layer 61 is located in one groove 11 and the height of the AlN filling layer 61 is lower than the depth of the groove 11. The GaN planarization layer covers the surface of the AlN nucleation layer 6 and the surface of the substrate 1.

[0043] Adding the AlN nucleation layer 6 and the GaN planarization layer between the substrate 1 and the n-type composite layer 2 can relieve lattice mismatch and improve the quality of the obtained n-type composite layer 2 and multi-quantum well layer 3. And there are a plurality of grooves 11 on the substrate 1. The AlN nucleation layer 6 includes a plurality of AlN filling layers 61 corresponding to the grooves 11 one by one. The height of the AlN filling layer 61 is lower than the depth of the groove 11. The AlN filling layer 61 can provide a good growth basis for the growth of gallium nitride materials. At the same time, a part of the GaN planarization layer can be located in the groove 11, increasing the connection strength between the GaN planarization layer and the substrate 1 to ensure the stable use of the epitaxial wafer. The side walls of the groove 11 can also block the extension of dislocations to a certain extent, effectively improving the crystal quality of the n-type composite layer 2 and multi-quantum well layer 3 grown on the substrate 1 and the GaN planarization layer.

[0044] Exemplarily, the ratio of the height of the AlN nucleation layer 6 to the depth of the groove 11 is 1:50 to 1:1000.

[0045] When the ratio of the height of the AlN nucleation layer 6 to the depth of the groove 11 is within the above range, the quality of the obtained AlN nucleation layer 6 and GaN planarization layer can be improved to improve the quality of the finally obtained n-type composite layer 2 and multi-quantum well layer 3.

[0046] Optionally, the thickness of the AlN nucleation layer 6 is 15 to 2000 nm, and the thickness of the GaN planarization layer is 1 to 5 μm.

[0047] When the thickness of the AlN nucleation layer 6 and the thickness of the GaN planarization layer are within the above range, the quality of the obtained AlN nucleation layer 6 and GaN planarization layer can be improved to improve the quality of the finally obtained n-type composite layer 2 and multi-quantum well layer 3.

[0048] Optionally, the multi-quantum well layer 3 includes alternately stacked InGaN well layers and GaN barrier layers, which can ensure the stable light emission of the light-emitting diode.

[0049] Optionally, the Al component in the AlGaN electron blocking layer 8 can be 0.15 to 0.25, and the effect of blocking electrons is better.

[0050] Optionally, the p-type GaN layer 4 may be doped with Mg, and the thickness of the p-type GaN layer 4 may be the same as that of the structure shown in Figure 1 , which will not be elaborated here.

[0051] Exemplarily, the material of the p-type contact layer 5 may be a gallium nitride material, and the thickness of the p-type contact layer 5 may be 30-100 nm. It can ensure a good ohmic contact is formed between the p-type contact layer 5 and the electrode to improve the quality of the finally obtained light-emitting diode.

[0052] It should be noted that Figure 2 compared with the epitaxial wafer structure shown in Figure 1 , an AlN nucleation layer 6 and a GaN planarization layer are added between the substrate 1 and the n-type composite layer 2, and at the same time, the structure of the electron blocking layer 8 is also added. The quality and light-emitting efficiency of the obtained epitaxial wafer will be better.

[0053] Figure 3 is a flowchart of a method for preparing an epitaxial wafer of a light-emitting diode for improving the internal quantum efficiency. Referring to Figure 3 , the embodiments of the present disclosure provide a method for preparing an epitaxial wafer of a light-emitting diode for improving the internal quantum efficiency. The preparation method includes:

[0054] S101: Provide a substrate.

[0055] S102: Sequentially grow an n-type composite layer, a multi-quantum well layer, a p-type GaN layer, and a p-type contact layer on the substrate. The n-type composite layer includes a gallium aluminum nitride layer, a first gallium nitride layer, a first silicon-doped gallium nitride layer, a second silicon-doped gallium nitride layer, and a silicon-doped aluminum nitride layer stacked in sequence. The doping concentration of silicon in the first silicon-doped gallium nitride layer is less than that in the second silicon-doped gallium nitride layer, and the doping concentration of silicon in the silicon-doped aluminum nitride layer is lower than that in the first silicon-doped gallium nitride layer.

[0056] In a light-emitting diode epitaxial wafer, the n-type composite layer includes a gallium aluminum nitride layer, a first gallium nitride layer, a first silicon-doped gallium nitride layer, a second silicon-doped gallium nitride layer, and a silicon-doped aluminum nitride layer stacked in sequence. The gallium aluminum nitride layer can block the electrons near the multi-quantum well layer from flowing towards the substrate or the structure below the n-type composite layer, avoiding electron backflow. The silicon-doped aluminum nitride layer can avoid electron backflow. At the same time, due to the doping of a certain amount of silicon element, the resistance to electrons is not too large, which can reduce electron backflow and play a certain role in current spreading, facilitating the improvement of the light-emitting efficiency and the light extraction uniformity of the light-emitting diode. The first gallium nitride layer can play a good transition role, ensuring good quality of the n-type composite layer, and can also block electron backflow to a certain extent, reducing the possibility of current breakdown. The first silicon-doped gallium nitride layer and the second silicon-doped gallium nitride layer can stably provide electrons. The doping concentration of silicon in the first silicon-doped gallium nitride layer is less than that in the second silicon-doped gallium nitride layer, and the doping concentration of silicon in the silicon-doped aluminum nitride layer is lower than that in the first silicon-doped gallium nitride layer, which can ensure sufficient electrons in the part close to the multi-quantum well layer, promoting the flow of electrons towards the multi-quantum well layer. At the same time, there are also some electrons on the side of the n-type composite layer far from the multi-quantum well layer, which can make it easier for electrons to flow towards the multi-quantum well layer with almost no electrons, improving the uniformity and quantity of electrons entering the multi-quantum well layer, and enhancing the internal quantum efficiency of the light-emitting diode, as well as the light extraction uniformity and light extraction efficiency of the light-emitting diode.

[0057] Optionally, the first silicon-doped gallium nitride layer is grown in an atmosphere environment of hydrogen and ammonia, and the volume ratio of hydrogen to ammonia in the atmosphere environment of the first silicon-doped gallium nitride layer is 1.5:1 to 2:1.

[0058] Growing the first silicon-doped gallium nitride layer in an atmosphere environment of hydrogen and ammonia can promote the flow of silicon in the first silicon-doped gallium nitride layer and the uniform growth of the first silicon-doped gallium nitride layer, thereby improving the crystal quality of the first silicon-doped gallium nitride layer.

[0059] Exemplarily, the other layers in the n-type composite layer except the first silicon-doped gallium nitride layer can be grown in an atmosphere environment of hydrogen and ammonia, and in the atmosphere environment of the other layers in the n-type composite layer except the first silicon-doped gallium nitride layer, the volume ratio of hydrogen to ammonia can be 1:1 to 3:2. This can ensure the crystal quality of the n-type composite layer while effectively reducing the preparation cost of the n-type composite layer.

[0060] Exemplarily, the growth temperature and growth pressure of the n-type composite layer can be 850 - 1200 °C and 100 - 300 torr respectively.

[0061] When the growth temperature and growth pressure of the n-type composite layer are within the above ranges, the crystal quality of the obtained n-type composite layer can be improved while reasonably controlling the preparation cost of the n-type composite layer. At the same time, the compactness of the crystals inside the n-type composite layer can be made relatively high, which can reduce the electron migration rate to a certain extent, enabling holes to have more time to move into the multi-quantum well layer relative to electrons, thereby improving the luminous efficiency of the light-emitting diode.

[0062] Optionally, the growth rotation speed of the n-type composite layer is 500 - 800 rpm.

[0063] When the growth rotation speed of the n-type composite layer is within the above range, a relatively compact n-type composite layer can be obtained to reduce the electron migration rate to a certain extent.

[0064] Exemplarily, the growth rotation speeds of the aluminum gallium nitride layer, the first gallium nitride layer, the first silicon-doped gallium nitride layer, the second silicon-doped gallium nitride layer, and the silicon-doped aluminum nitride layer can be 500 - 800 rpm, 500 - 800 rpm, 500 - 800 rpm, 500 - 800 rpm, and 500 - 800 rpm respectively.

[0065] When the growth rotation speeds of each layer in the n-type composite layer are within the above ranges respectively, the quality of the n-type composite layer can be ensured to be good, and the compactness and crystal quality of the first silicon-doped gallium nitride layer and the second silicon-doped gallium nitride layer, which mainly provide electrons, are good. While providing sufficient electrons, the electron migration rate can be reduced to a certain extent.

[0066] Figure 4 It is a flowchart of another method for preparing a light-emitting diode epitaxial wafer with improved internal quantum efficiency provided by an embodiment of the present disclosure. Refer to Figure 4 It can be seen that the method for preparing the light-emitting diode epitaxial wafer includes:

[0067] S201: Provide a substrate and fabricate a plurality of grooves on the substrate.

[0068] Among them, the substrate can be a sapphire substrate, which is easy to implement and fabricate.

[0069] It should be noted that the grooves can be obtained through a photolithography process, which can ensure the quality of the obtained grooves.

[0070] S202: Grow an AlN nucleation layer on the substrate. The AlN nucleation layer includes a plurality of AlN filling layers corresponding one-to-one to the grooves, and each AlN filling layer is located in a groove and the height of the AlN filling layer is lower than the depth of the groove.

[0071] Exemplarily, the deposition temperature of the AlN layer can be 400 - 800 °C, the sputtering power can be 3000 - 5000 W, and the pressure can be 2 - 20 mtorr. The obtained AlN layer has good quality.

[0072] S203: Grow a GaN planarization layer on the AlN nucleation layer, where the GaN planarization layer covers the surfaces of both the AlN nucleation layer and the substrate.

[0073] Exemplarily, the growth temperature of the undoped GaN layer can be 1000 - 1100 °C, and the growth pressure is controlled at 100 - 300 torr. The obtained undoped GaN layer has good quality.

[0074] S204: Grow an n-type composite layer on the GaN planarization layer.

[0075] Step S204 can refer to Figure 3 Step S102 shown in [reference], so it will not be elaborated here.

[0076] S205: Grow a multi-quantum well layer on the n-type composite layer.

[0077] In step S205, the multi-quantum well layer includes alternately stacked InGaN well layers and GaN barrier layers, and alternately stacked InGaN well layers and GaN barrier layers can be obtained by alternately introducing different reaction materials into the reaction chamber.

[0078] S206: Grow an AlGaN electron blocking layer on the multi-quantum well layer.

[0079] The growth temperature of the AlGaN electron blocking layer can be 800 - 1000 °C, and the growth pressure of the AlGaN electron blocking layer can be 100 - 300 Torr. The AlGaN electron blocking layer grown under these conditions has good quality, which is beneficial to improving the light emission efficiency of the light-emitting diode.

[0080] S207: Grow a p-type GaN layer on the AlGaN electron blocking layer.

[0081] Optionally, the growth pressure of the p-type GaN layer can be 200 - 600 Torr, and the growth temperature of the p-type GaN layer can be 800 - 1000 °C.

[0082] S208: Grow a p-type contact layer on the p-type GaN layer.

[0083] Optionally, the growth pressure of the p-type contact layer can be 200 - 600 Torr, and the growth temperature of the p-type contact layer can be 800 - 1000 °C.

[0084] It should be noted that in the embodiments of the present disclosure, a Veeco K465i or C4 or RBM O CVD (Metal Organic Chemical Vapor Deposition) apparatus is used to implement the method for growing light-emitting diodes. High-purity H2 (hydrogen gas), or high-purity N2 (nitrogen gas), or a mixed gas of high-purity H2 and high-purity N2 is used as the carrier gas, high-purity NH3 is used as the N source, trimethylgallium (TMGa) and triethylgallium (TEGa) are used as the gallium sources, trimethylindium (TMIn) is used as the indium source, silane (SiH4) is used as the N-type dopant, trimethylaluminum (TMAl) is used as the aluminum source, and bis(cyclopentadienyl)magnesium (CP2Mg) is used as the P-type dopant.

[0085] The above are only optional embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A light-emitting diode epitaxial wafer for improving internal quantum efficiency, characterized in that The light-emitting diode epitaxial wafer for improving the internal quantum efficiency includes a substrate and an n-type composite layer, a multi-quantum well layer, a p-type GaN layer, and a p-type contact layer that are sequentially stacked on the substrate. The n-type composite layer includes a gallium aluminum nitride layer, a first gallium nitride layer, a first silicon-doped gallium nitride layer, a second silicon-doped gallium nitride layer, and a silicon-doped aluminum nitride layer that are sequentially stacked. The doping concentration of silicon in the first silicon-doped gallium nitride layer is less than the doping concentration of silicon in the second silicon-doped gallium nitride layer, and the doping concentration of silicon in the silicon-doped aluminum nitride layer is lower than the doping concentration of silicon in the first silicon-doped gallium nitride layer.

2. The light-emitting diode epitaxial wafer according to claim 1, wherein The ratios of the thickness of the gallium aluminum nitride layer, the thickness of the silicon-doped aluminum nitride layer, and the thickness of the n-type composite layer are all 1:5 to 1:15, and the ratios of the thickness of the first silicon-doped gallium nitride layer, the thickness of the second silicon-doped gallium nitride layer, and the thickness of the n-type composite layer are all 1:80 to 1:

150.

3. The light-emitting diode epitaxial wafer according to claim 1, wherein, The thicknesses of the gallium aluminum nitride layer, the first gallium nitride layer, the first silicon-doped gallium nitride layer, the second silicon-doped gallium nitride layer, and the silicon-doped aluminum nitride layer are all 1 to 3 microns.

4. The light-emitting diode epitaxial wafer according to any one of claims 1 to 3, wherein The thickness of the first silicon-doped gallium nitride layer is less than the thickness of the second silicon-doped gallium nitride layer.

5. The light-emitting diode epitaxial wafer according to any one of claims 1 to 3, characterized in that, The light-emitting diode epitaxial wafer for improving the internal quantum efficiency further includes an AlN nucleation layer and a GaN planarization layer. The AlN nucleation layer and the GaN planarization layer are sequentially stacked and are both located between the substrate and the n-type composite layer. The substrate has a plurality of grooves spaced apart from each other. The AlN nucleation layer includes a plurality of AlN filling layers corresponding to the grooves one by one. Each AlN filling layer is located in one of the grooves and the height of the AlN filling layer is lower than the depth of the groove. The GaN planarization layer covers the surface of the AlN nucleation layer and the surface of the substrate.

6. The light-emitting diode epitaxial wafer according to claim 5, characterized in that The ratio of the height of the AlN nucleation layer to the depth of the groove is 1:50 to 1:1000.

7. The light-emitting diode epitaxial wafer according to claim 5, wherein, The thickness of the AlN nucleation layer is 15 to 2000 nm, and the thickness of the GaN planarization layer is 1 to 5 μm.

8. A method for preparing a light-emitting diode epitaxial wafer with improved internal quantum efficiency, characterized in that, The preparation method includes: Providing a substrate; Growing an n-type composite layer, a multi-quantum well layer, a p-type GaN layer, and a p-type contact layer on the substrate in sequence. The n-type composite layer includes a gallium aluminum nitride layer, a first gallium nitride layer, a first silicon-doped gallium nitride layer, a second silicon-doped gallium nitride layer, and a silicon-doped aluminum nitride layer that are sequentially stacked. The doping concentration of silicon in the first silicon-doped gallium nitride layer is less than the doping concentration of silicon in the second silicon-doped gallium nitride layer, and the doping concentration of silicon in the silicon-doped aluminum nitride layer is lower than the doping concentration of silicon in the first silicon-doped gallium nitride layer.

9. The preparation method according to claim 8, characterized in that, The first silicon-doped gallium nitride layer is grown in an atmosphere environment of hydrogen and ammonia, and the volume ratio of hydrogen to ammonia in the atmosphere environment of the first silicon-doped gallium nitride layer is 1.5:1 to 2:

1.

10. The preparation method according to claim 9, wherein, The growth rotation speed of the n-type composite layer is 500 to 800 rpm.

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