CN112366255A - Light emitting diode epitaxial wafer and preparation method thereof - Google Patents

Light emitting diode epitaxial wafer and preparation method thereof Download PDF

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CN112366255A
CN112366255A CN202011061495.0A CN202011061495A CN112366255A CN 112366255 A CN112366255 A CN 112366255A CN 202011061495 A CN202011061495 A CN 202011061495A CN 112366255 A CN112366255 A CN 112366255A
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gan
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type impurities
nucleation
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CN112366255B (en
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姚振
从颖
董彬忠
李鹏
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HC Semitek Zhejiang Co Ltd
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HC Semitek Zhejiang Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/025—Physical imperfections, e.g. particular concentration or distribution of impurities
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005—Processes
    • H01L33/0062—Processes for devices with an active region comprising only III-V compounds
    • H01L33/0066—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound
    • H01L33/007—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound comprising nitride compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/12—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a stress relaxation structure, e.g. buffer layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/26—Materials of the light emitting region
    • H01L33/30—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table
    • H01L33/32—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table containing nitrogen
    • H01L33/325—Materials of the light emitting region containing only elements of Group III and Group V of the Periodic Table containing nitrogen characterised by the doping materials

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Abstract

The disclosure provides a light emitting diode epitaxial wafer and a preparation method thereof, and belongs to the technical field of light emitting diodes. The nucleating layer, the GaN filling layer and the n-type GaN layer which are sequentially stacked on the GaN buffer layer are all doped with n-type impurities. The doping concentration of n-type impurities in the nucleation layer and the GaN filling layer is gradually increased, so that the defects existing in the bottom layer are reduced, and a good growth foundation is provided for the epitaxial structure grown subsequently to reduce the defects. The doping concentration of n-type impurities in the n-type GaN layer is 2E 8-6E18/cm3The doping concentration of n-type impurities in the n-type GaN layer is greatly reduced compared with the conventional n-type GaN layer, the doped Si source is dispersed into the GaN filling layer and the nucleation layer, the density of defects is reduced, the quality of the n-type GaN layer can be improved,the quality of the active layer grown on the n-type GaN layer can be improved, and the quality of the finally obtained light emitting diode epitaxial wafer is improved.

Description

Light emitting diode epitaxial wafer and preparation method thereof
Technical Field
The disclosure relates to the technical field of light emitting diodes, and particularly relates to a light emitting diode epitaxial wafer and a preparation method thereof.
Background
The light emitting diode is a light emitting device with wide application, and is commonly used for communication signal lamps, automobile interior and exterior lamps, urban illumination, landscape illumination and the like, and the light emitting diode epitaxial wafer is a basic structure for preparing the light emitting diode. The light emitting diode epitaxial wafer generally includes a substrate and a GaN buffer layer, a nucleation layer, an undoped GaN layer, an n-type GaN layer, an active layer and a p-type GaN layer sequentially stacked on the substrate.
In the related art, the n-type GaN layer in the led epitaxial wafer is a semiconductor material for providing electrons, and in order to provide sufficient electrons, the n-type GaN layer is usually doped with a large amount of n-type impurities. However, the doping of n-type impurities is more, which may cause more defects in the n-type GaN layer, and the defects in the n-type GaN layer may easily extend and move into the active layer, which may cause more defects in the active layer, and non-radiative recombination between electrons and holes in the defects, which may affect the light emitting efficiency of the light emitting diode epitaxial wafer.
Disclosure of Invention
The embodiment of the disclosure provides a light emitting diode epitaxial wafer and a preparation method thereof, which can improve the luminous efficiency of the finally obtained light emitting diode epitaxial wafer by the crystal quality of an n-type GaN layer. The technical scheme is as follows:
the disclosed embodiment provides a light emitting diode epitaxial wafer, which comprises a substrate, and a GaN buffer layer, a nucleation layer, a GaN filling layer, an n-type GaN layer, an active layer and a p-type GaN layer which are sequentially stacked on the substrate,
the GaN filling layer and the nucleation layer are doped with n-type impurities, the doping concentration of the n-type impurities in the nucleation layer, the doping concentration of the n-type impurities in the GaN filling layer and the doping concentration of the n-type impurities in the n-type GaN layer are sequentially increased, and the doping concentration of the n-type impurities in the n-type GaN layer is 2E 8-6E18/cm3。
Optionally, the nucleation layer includes a first GaN nucleation layer and a second GaN nucleation layer which are alternately stacked, the first GaN nucleation layer is made of a GaN material doped with n-type impurities, and the second GaN nucleation layer is made of an undoped GaN material.
Optionally, the doping concentration of the n-type impurity in the first GaN nucleating layer is 1E 17-6E 17/cm3。
Optionally, the doping concentration of the n-type impurity in the GaN fill-flat layer increases and then decreases in the growth direction of the GaN fill-flat layer.
Optionally, the doping concentration of the n-type impurity in the GaN filling layer is 5-10 times of the doping concentration of the n-type impurity in the nucleation layer.
Optionally, the doping concentration of the n-type impurity in the GaN filling layer is 0.15-0.5 times of the doping concentration of the n-type impurity in the n-type GaN layer.
Optionally, the doping concentration of the n-type impurity in the GaN filling layer is 1E18-6E18/cm3。
The embodiment of the disclosure provides a preparation method of a light-emitting diode epitaxial wafer, which comprises the following steps:
providing a substrate;
growing a GaN buffer layer on the substrate;
growing a nucleation layer on the GaN buffer layer, wherein n-type impurities are doped in the nucleation layer;
growing a GaN filling layer on the nucleating layer, wherein n-type impurities are doped in the GaN filling layer, and the doping concentration of the n-type impurities in the GaN filling layer is greater than that of the n-type impurities in the nucleating layer;
growing an n-type GaN layer on the GaN filling layer, wherein the doping concentration of n-type impurities in the nucleation layer is greater than that of the n-type impurities in the GaN filling layer, and the doping concentration of the n-type impurities in the n-type GaN layer is 2E 8-6E18/cm3；
Growing an active layer on the n-type GaN layer;
and growing a p-type GaN layer on the active layer.
Optionally, the growing an n-type GaN layer on the GaN fill-up layer includes:
and introducing reaction gas into the reaction cavity and introducing a Si source discontinuously, and growing an n-type GaN layer on the GaN filling layer.
Optionally, 180-300 s of Si source with the flow rate of 40-80 is introduced into the reaction cavity every time.
The beneficial effects brought by the technical scheme provided by the embodiment of the disclosure include:
in the light emitting diode epitaxial wafer provided by the present disclosure, the GaN buffer layer is still grown on the substrate first and is used for alleviating lattice mismatch between subsequent materials and the substrate. The nucleating layer, the GaN filling layer and the n-type GaN layer which are sequentially stacked on the GaN buffer layer are all doped with n-type impurities, the doping concentration of the n-type impurities in the nucleating layer and the GaN filling layer is gradually increased, and the doping concentration of the n-type impurities in the n-type GaN layer is 2E 8-6E18/cm3. The nucleation layer and the GaN filling layer disperse the concentration of n-type impurities needing to be doped in the original n-type GaN layer, and the nucleation layer, the GaN filling layer and the n-type GaN layer are used as donors for providing electrons, so that even if the doping concentration of the n-type impurities in the n-type GaN layer is far smaller than that of the n-type impurities in the traditional n-type GaN layer, sufficient electrons can be ensured to enter the active layer for compounding. On the basis, the doped n-type impurities in the nucleation layer closer to the substrate are relatively less, so that the defects existing in the bottom layer can be reduced as much as possible, and a good growth basis is provided for the subsequent epitaxial structure to reduce the defects. And because the doped Si source is dispersed in the GaN filling layer and the nucleating layer, although defects still can be generated, compared with the defects generated when the Si source is concentrated on the n-type GaN layer, the density of the defects can be greatly reduced, the quality of the n-type GaN layer can be improved, and the quality of an active layer grown on the n-type GaN layer can be improved. And the energy is also required for moving the defects in the crystal, and the energy required for moving the defects in the nucleation layer and the GaN filling layer to the active layer is far more than that required for moving the defects in the n-type GaN layer to the active layer. Defects that enough energy moves into the active layer are reduced, the quality of the active layer is further improved, and the quality of the finally obtained light emitting diode epitaxial wafer is improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an led epitaxial wafer according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of another light emitting diode epitaxial wafer according to an embodiment of the present disclosure;
fig. 3 is a flowchart of a method for manufacturing an epitaxial wafer of a light emitting diode according to an embodiment of the present disclosure;
fig. 4 is a flowchart of another method for manufacturing an epitaxial wafer of a light emitting diode according to an embodiment of the present disclosure.
Detailed Description
To make the objects, technical solutions and advantages of the present disclosure more apparent, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
Fig. 1 is a schematic structural diagram of an led epitaxial wafer according to an embodiment of the present disclosure. As can be seen from fig. 1, the present disclosure provides a light emitting diode epitaxial wafer, which includes a substrate 1, and a GaN buffer layer 2, a nucleation layer 3, a GaN fill-up layer 4, an n-type GaN layer 5, an active layer 6, and a p-type GaN layer 7 sequentially stacked on the substrate 1.
The nucleation layer 3 and the GaN filling layer 4 are doped with n-type impurities, the doping concentration of the n-type impurities in the nucleation layer 3, the doping concentration of the n-type impurities in the GaN filling layer 4 and the doping concentration of the n-type impurities in the n-type GaN layer 5 are sequentially increased, and the doping concentration of the n-type impurities in the n-type GaN layer 5 is 2E 8-6E18/cm3。
In the light emitting diode epitaxial wafer provided by the present disclosure, the GaN buffer layer 2 is still grown on the substrate 1 first, and is used for alleviating lattice mismatch between subsequent materials and the substrate 1. The nucleating layer 3, the GaN filling layer 4 and the n-type GaN layer 5 which are sequentially laminated on the GaN buffer layer 2 are all doped with n-type impurities, and the n-type impurities in the nucleating layer 3 and the GaN filling layer 4The doping concentration is gradually increased, and the doping concentration of the n-type impurities in the n-type GaN layer 5 is 2E 8-6E18/cm3. The nucleation layer 3 and the GaN leveling layer 4 disperse the concentration of the n-type impurity to be doped in the original n-type GaN layer 5, and the nucleation layer 3, the GaN leveling layer 4 and the n-type GaN layer 5 are both used as donors for providing electrons, so that even if the doping concentration of the n-type impurity in the n-type GaN layer 5 is far less than that of the n-type impurity in the conventional n-type GaN layer 5, sufficient electrons can be ensured to enter the active layer 6 for recombination. On the basis, the doped n-type impurities in the nucleation layer 3 closer to the substrate 1 are relatively less, so that the defects existing in the bottom layer can be reduced as much as possible, and a good growth foundation is provided for the subsequent epitaxial structure to reduce the defects. Moreover, since the doped Si source is dispersed in the GaN fill-up layer 4 and the nucleation layer 3, although defects are still generated, the density of defects is greatly reduced, the quality of the n-type GaN layer 5 itself can be improved, and the quality of the active layer 6 grown on the n-type GaN layer 5 can be improved, compared with the defects generated when Si sources are all concentrated on the n-type GaN layer 5. And the energy is also required for moving the defects in the crystal, and the energy required for moving the defects in the nucleation layer 3 and the GaN filling layer 4 into the active layer 6 is far more than that required for moving the defects in the n-type GaN layer 5 into the active layer 6. Defects with sufficient energy to move into the active layer 6 are also reduced, the quality of the active layer 6 is further improved, and the quality of the finally obtained light emitting diode epitaxial wafer is improved.
Note that, as the n-type doping concentration in the n-type GaN layer 5 decreases, the quality of the n-type GaN layer 5 itself also increases, and the quality of the active layer 6 grown on the n-type GaN layer 5 can naturally increase.
Note that the nucleation layer 3 is actually a plurality of GaN island-like structures 3a distributed at intervals on the GaN buffer layer 2.
Alternatively, the thickness of the nucleation layer 3 may be 20 to 80nm as a whole. Can stably supply electrons and establish a good growth base.
As can be seen from fig. 1, the nucleation layer 3 may include first GaN nucleation layers 31 and second GaN nucleation layers 32 alternately stacked, the first GaN nucleation layers 31 being made of a GaN material doped with n-type impurities, and the second GaN nucleation layers 32 being made of an undoped GaN material.
The concentration of n-type impurity doping in the nucleation layer 3 is low, but a certain current channel can be provided to ensure the supply of electrons. And the first GaN nucleation layer 31 doped with n-type impurities and the second GaN nucleation layer 32 not doped with n-type impurities are alternately grown during the growth of the nucleation layer 3, and the small amount of n-type impurities doped in the first GaN nucleation layer 31 can promote the viscosity of the volume of the GaN island-shaped structures 3a and increase the volume of each individual GaN island-shaped structure 3 a. The volume of each single GaN island-shaped structure 3a is increased, the GaN filling layer 4 continues to grow on the GaN island-shaped structures 3a, and when the film-shaped GaN filling layer 4 is synthesized in parallel, the number of grain boundary defects in the GaN filling layer 4 due to the combination of the island-shaped structures 3a is less, so that the growth quality of the GaN filling layer 4 growing on the nucleation layer 3 can be improved.
Optionally, the doping concentration of the n-type impurity in the first GaN nucleation layer 31 can be 1E 17-6E 17/cm3。
The nucleation layer 3 and the GaN-filled layer 4 obtained at this time have good overall quality, and the nucleation layer 3 can stably supply electrons.
Illustratively, the ratio of the content of Si to the composition of Ga in the nucleation layer 3 may be 0.01 to 0.02. The obtained nucleation layer 3 has good quality as a whole and is not easy to generate excessive defects.
Optionally, the thickness of the first GaN nucleation layer 31 may be 10 to 20nm, and the thickness of the second GaN nucleation layer 32 may be 15 to 30 nm. The quality of the resulting nucleation layer 3 is good and the quality of the GaN-filled layer 4 grown on the nucleation layer 3 is also good.
Optionally, the thickness of the GaN filling-up layer 4 can be 2-3.5 um. It is possible to fill in the nucleation layer 3 efficiently and to ensure the quality of the n-type GaN layer 5 grown on the GaN-filled layer 4.
Illustratively, the doping concentration of the n-type impurity in the GaN filled-up layer 4 may increase first and then decrease in the growth direction of the GaN filled-up layer 4.
When the GaN filling layer 4 is initially grown on the nucleation layer 3, the doping concentration of n-type doping is small, which can realize good transition with the nucleation layer 3 and ensure the quality of the part directly grown on the rough nucleation layer 3. The higher doping concentration of the n-type doping in the middle of the GaN filled layer 4 can effectively provide enough electrons to ensure that the number of electrons finally entering the active layer 6 is enough. The doping concentration of the n-type doping at the end of the GaN filled layer 4 is further reduced, so that the electron concentration at the end of the GaN filled layer 4 is naturally lower than that at the middle of the GaN filled layer 4 when not energized, and electrons more easily enter the middle of the GaN filled layer 4 with high electron concentration into the end of the GaN filled layer 4 with low electron concentration and then enter the n-type GaN layer 5 when energized. While ensuring stable flow of electrons, defects that may be present in the GaN filled-up layer 4 are reduced, and the manufacturing cost of the GaN filled-up layer 4 is reduced.
Optionally, the doping concentration of the n-type impurity in the GaN filling-up layer 4 may be 5 to 10 times of the doping concentration of the n-type impurity in the nucleation layer 3.
The doping concentration of the n-type impurities in the GaN filling layer 4 is 5-10 times of that of the n-type impurities in the nucleation layer 3, the GaN filling layer 4 can stably grow on the nucleation layer 3 and is finally transited to the n-type GaN layer 5, and the growth quality of the GaN filling layer 4 and the growth quality of the n-type GaN layer 5 can be improved.
Optionally, the doping concentration of the n-type impurities in the GaN filling-up layer 4 is 0.15 to 0.5 times of the doping concentration of the n-type impurities in the n-type GaN layer 5. Can be stably transited to the n-type GaN layer 5, and ensures the crystal quality of the obtained n-type GaN layer 5.
Illustratively, the doping concentration of the n-type impurity in the GaN fill-up layer 4 is 1E18-6E18/cm3. The obtained GaN filled-up layer 4 can stably supply electrons, and the crystal quality of the GaN filled-up layer 4 is also good.
Illustratively, the ratio of the content of Si to the composition of Ga in the GaN fill-up layer 4 may be 0.02 to 0.04. A good transition can be achieved on the basis of the nucleation layer 3, without the risk of excessive defects.
Optionally, the thickness of the n-type GaN layer 5 can be 2-3 um. It is possible to efficiently supply electrons and to ensure the quality of the active layer 6 grown on the n-type GaN layer 5.
Fig. 2 is a schematic structural diagram of another light emitting diode epitaxial wafer according to an embodiment of the present disclosure, and as can be seen from fig. 2, in another implementation manner provided by the present disclosure, the light emitting diode epitaxial wafer may include a substrate 1, and a GaN buffer layer 2, a nucleation layer 3, a GaN filling layer 4, an n-type GaN layer 5, an active layer 6, an electron blocking layer 8, and a p-type GaN layer 7, which are sequentially stacked and grown on the substrate 1.
It should be noted that the structures of the nucleation layer 3, the GaN filled-up layer 4 and the n-type GaN layer 5 shown in fig. 2 are the same as the structures of the nucleation layer 3, the GaN filled-up layer 4 and the n-type GaN layer 5 shown in fig. 1, and thus the description thereof is omitted.
Alternatively, the substrate 1 may be a sapphire substrate 1. Easy to manufacture and obtain.
Alternatively, the thickness of the GaN buffer layer 2 may be 10-30 nm. The lattice mismatch between the n-type GaN layer 5 and the substrate 1 can be reduced, and the growth quality of the light-emitting diode epitaxial wafer is ensured.
Exemplarily, the active layer 6 may include GaN barrier layers 62 and InGaN well layers 61 alternately stacked. The thickness of the GaN barrier layer 62 can be 8-15 nm, and the thickness of the InGaN well layer 61 can be 1.5-3 nm.
Alternatively, the electron blocking layer 8 may be Mg-doped AlyGa1-yN layers, wherein y ranges from 0.15 to 0.25. The effect of blocking electrons is better.
Illustratively, the thickness of the electron blocking layer 8 may be 30 to 50 nm. The LED epitaxial wafer has good overall quality.
Optionally, the p-type GaN layer 7 can be doped with Mg, and the thickness of the p-type GaN layer 7 can be 50-80 nm. The obtained p-type GaN layer 7 has good quality as a whole.
Note that in implementations provided in the present disclosure, the n-type impurity may be Si.
Fig. 3 is a flowchart of a method for manufacturing an led epitaxial wafer according to an embodiment of the present disclosure, and as shown in fig. 3, the method for manufacturing an led epitaxial wafer includes:
s101: a substrate is provided.
S102: a nucleation layer is grown on the substrate.
S103: and growing a nucleation layer on the GaN buffer layer, wherein n-type impurities are doped in the nucleation layer.
The nucleation layer may include first and second GaN nucleation layers alternately stacked, the first GaN nucleation layer being made of a GaN material doped with n-type impurities, the second GaN nucleation layer being made of an undoped GaN material.
Optionally, when the first GaN nucleating layer is grown, a Si source with the flow rate of 5-20 sccm is introduced into the reaction cavity. A nucleation layer of good quality and providing sufficient electrons can be obtained.
In another implementation manner provided by the present disclosure, when the first GaN nucleation layer is grown, a Si source with a flow rate of 5 to 16sccm may be introduced into the reaction chamber. The quality of the resulting nucleation layer can be further improved.
Illustratively, the growth temperature of the nucleation layer can be 1000-1050 ℃, and the growth pressure of the nucleation layer can be 200-500 torr. The quality of the finally obtained nucleation layer can be ensured to be better.
S104: and growing a GaN filling layer on the nucleating layer, wherein n-type impurities are doped in the GaN filling layer, and the doping concentration of the n-type impurities in the GaN filling layer is greater than that of the n-type impurities in the nucleating layer.
Optionally, when the GaN filling layer grows, Si sources with the flow rate of 5-10 sccm, 15-30 sccm and 5-15 sccm are sequentially introduced into the reaction cavity. A GaN fill-up layer of good quality and sufficient electron supply can be obtained.
Illustratively, when the GaN leveling layer grows, the quality of the GaN leveling layer obtained by introducing the Si source with the flow rate of 5-10 sccm into the reaction cavity for 3-5 min is good.
Illustratively, the growth temperature of the GaN filling layer can be 1090-1120 ℃, and the growth pressure of the GaN filling layer can be 150-300 torr. The quality of the finally obtained GaN filling and leveling layer can be ensured to be better.
S105: growing an n-type GaN layer on the GaN filling layer, wherein the doping concentration of n-type impurities in the nucleation layer is greater than that of the GaN filling layer, and the doping concentration of the n-type impurities in the n-type GaN layer is 2E 8-6E18/cm3。
In step S105, growing an n-type GaN layer on the GaN fill-up layer, which may include:
and introducing reaction gas into the reaction cavity and introducing a Si source discontinuously, and growing an n-type GaN layer on the GaN filling layer.
Reaction gas is introduced into the reaction cavity and the Si source is introduced discontinuously, so that enough electrons can be provided in the obtained n-type GaN layer, meanwhile, the part, which is not introduced with the Si source, of the n-type GaN layer has a small number of electrons, a certain electron blocking effect can be achieved to a certain extent, a slight current expansion effect can be achieved, and the distribution of electrons finally entering the active layer is more uniform. In addition, the growing mode has better quality of the part with less Si source doping in the n-type GaN layer, can further disperse the defect density, and reduces the number of the defects which can extend to the active layer so as to improve the crystal quality of the active layer.
Optionally, 180-300 s of Si source with the flow rate of 40-80 is introduced into the reaction cavity every time. The obtained n-type GaN can be ensured to have better quality and relatively uniform distribution.
Illustratively, the Si source can be introduced into the reaction cavity once every time at intervals of 200-250 s.
And introducing a Si source into the reaction cavity at intervals of 200-250 s every time, wherein the time is not long enough, the n-type GaN layer in the reaction cavity still performs reaction growth, but a GaN layer which is not doped completely is not formed, so that the quality of the n-type GaN layer is effectively improved while the n-type GaN layer can stably provide electrons.
Illustratively, the growth temperature of the n-type GaN layer can be 1080-1110 ℃, and the growth pressure of the n-type GaN layer can be 100-250 torr. The quality of the finally obtained n-type GaN layer can be ensured to be better.
S106: an active layer is grown on the n-type GaN layer.
S107: and growing a p-type GaN layer on the active layer.
In the light emitting diode epitaxial wafer provided by the present disclosure, the GaN buffer layer is still grown on the substrate first and is used for alleviating lattice mismatch between subsequent materials and the substrate. The nucleating layer, the GaN filling layer and the n-type GaN layer which are sequentially stacked on the GaN buffer layer are all doped with n-type impurities, the doping concentration of the n-type impurities in the nucleating layer and the GaN filling layer is gradually increased, and the doping concentration of the n-type impurities in the n-type GaN layer is 2E 8-6E18/cm3. The nucleating layer and the GaN filling layer disperse the concentration of n-type impurities to be doped in the original n-type GaN layer, and the nucleating layer, the GaN filling layer and the n-type GaN layer are used as donors for providing electrons, even though the doping concentration of the n-type impurities in the n-type GaN layer is far less than that of the n-type impurities in the conventional n-type GaN layerThe doping concentration of the material can also ensure that enough electrons enter the active layer for recombination. On the basis, the doped n-type impurities in the nucleation layer closer to the substrate are relatively less, so that the defects existing in the bottom layer can be reduced as much as possible, and a good growth basis is provided for the subsequent epitaxial structure to reduce the defects. And because the doped Si source is dispersed in the GaN filling layer and the nucleating layer, although defects still can be generated, compared with the defects generated when the Si source is concentrated on the n-type GaN layer, the density of the defects can be greatly reduced, the quality of the n-type GaN layer can be improved, and the quality of an active layer grown on the n-type GaN layer can be improved. And the energy is also required for moving the defects in the crystal, and the energy required for moving the defects in the nucleation layer and the GaN filling layer to the active layer is far more than that required for moving the defects in the n-type GaN layer to the active layer. Defects that enough energy moves into the active layer are reduced, the quality of the active layer is further improved, and the quality of the finally obtained light emitting diode epitaxial wafer is improved. The structure of the light emitting diode epitaxial wafer after the step S104 is performed can be seen in fig. 1.
Fig. 4 is a flowchart of another method for manufacturing an led epitaxial wafer according to an embodiment of the present disclosure, and as shown in fig. 4, the method for manufacturing an led epitaxial wafer includes:
s201: a substrate is provided.
Wherein the substrate may be a sapphire substrate. Easy to realize and manufacture.
Optionally, step S201 may further include: and treating the surface of the substrate for 5-6 min under a hydrogen atmosphere.
For example, when processing the surface of the substrate, the temperature of the reaction chamber may be 1000 to 1100 ℃, and the pressure of the reaction chamber may be 200 to 500 torr.
S202: a GaN buffer layer is grown on the substrate.
Alternatively, the GaN buffer layer may be grown on the [0001] plane of the sapphire substrate. The GaN buffer layer is tightly combined with the sapphire substrate, and the obtained GaN buffer layer has good crystal quality.
Optionally, the thickness of the GaN buffer layer can be 10-30 nm.
Optionally, the growth temperature of the GaN buffer layer can be 530-560 ℃, and the growth pressure can be 200-500 Torr. The obtained GaN three-dimensional nucleation layer has better quality.
S203: and growing a nucleation layer on the GaN buffer layer.
S204: and growing a GaN filling layer on the nucleation layer.
S205: and growing an n-type GaN layer on the GaN filling layer.
It should be noted that the structures and growth manners in steps S203 to S205 are the same as those in steps S103 to 105 in fig. 3, and therefore are not described herein again.
S206: an active layer is grown on the n-type GaN layer.
The active layer includes GaN barrier layers and InGaN well layers alternately stacked. The growth temperature of the InGaN well layer can be 760-780 ℃, and the growth temperature of the GaN barrier layer can be 860-890 ℃. The active layer grown under the condition has good quality, and the luminous efficiency of the light-emitting diode can be ensured.
S207: an electron blocking layer is grown on the active layer.
Alternatively, the electron blocking layer may be Mg-doped AlyGa1-yN layers, wherein y ranges from 0.15 to 0.25. The effect of blocking electrons is better.
The growth thickness of the electron blocking layer can be 30-50 nm.
The growth temperature of the electron blocking layer can be 930-970 ℃, and the growth pressure of the electron blocking layer can be 100 Torr. The quality of the electron blocking layer grown under the condition is good, and the improvement of the luminous efficiency of the light-emitting diode is facilitated.
S208: and growing a p-type GaN layer on the electron blocking layer.
Alternatively, the growth pressure of the p-type GaN layer may be 200 to 600Torr, and the growth temperature of the p-type GaN layer may be 940 to 980 ℃.
The structure of the light emitting diode epitaxial wafer after the step S208 is performed can be seen in fig. 2, and the thicknesses of the layers in the light emitting diode epitaxial wafer are described in the light emitting diode epitaxial wafer shown in fig. 2, so the thicknesses of the layers in the epitaxial wafer are not described in detail in the structure shown in fig. 4.
It should be noted that, in the embodiments of the present disclosure, a VeecoK465iorC4 orrbmcvd (metalorganic chemical vapor deposition) apparatus is used to implement the growth method of the LED. By using high-purity H2(Hydrogen) or high purity N2(Nitrogen) or high purity H2And high purity N2The mixed gas of (2) is used as a carrier gas, high-purity NH3As an N source, trimethyl gallium (TMGa) and triethyl gallium (TEGa) as gallium sources, trimethyl indium (TMIn) as indium sources, silane (SiH4) as an N-type dopant, trimethyl aluminum (TMAl) as an aluminum source, and magnesium dicylocene (CP)2Mg) as a P-type dopant.
The above description is intended to be exemplary only and not to limit the present disclosure, and any modification, equivalent replacement, or improvement made without departing from the spirit and scope of the present disclosure is to be considered as the same as the present disclosure.

Claims (10)

1. A light emitting diode epitaxial wafer is characterized by comprising a substrate, and a GaN buffer layer, a nucleating layer, a GaN filling layer, an n-type GaN layer, an active layer and a p-type GaN layer which are sequentially stacked on the substrate,
the GaN filling layer and the nucleation layer are doped with n-type impurities, the doping concentration of the n-type impurities in the nucleation layer, the doping concentration of the n-type impurities in the GaN filling layer and the doping concentration of the n-type impurities in the n-type GaN layer are sequentially increased, and the doping concentration of the n-type impurities in the n-type GaN layer is 2E 8-6E18/cm3。
2. The light emitting diode epitaxial wafer of claim 1, wherein the nucleation layers comprise first GaN nucleation layers prepared for a GaN material doped with n-type impurities and second GaN nucleation layers prepared for an undoped GaN material, which are alternately stacked.
3. The light emitting diode epitaxial wafer of claim 2, wherein the doping of n-type impurities in the first GaN nucleation layerThe impurity concentration is 1E 17-6E 17/cm3。
4. The light-emitting diode epitaxial wafer as claimed in any one of claims 1 to 3, wherein the doping concentration of the n-type impurity in the GaN filling level layer increases and then decreases in the growth direction of the GaN filling level layer.
5. The light-emitting diode epitaxial wafer according to claim 4, wherein the doping concentration of the n-type impurities in the GaN filling layer is 5-10 times that of the n-type impurities in the nucleation layer.
6. The light-emitting diode epitaxial wafer as claimed in any one of claims 1 to 3, wherein the doping concentration of the n-type impurity in the GaN filling layer is 0.15 to 0.5 times that of the n-type impurity in the n-type GaN layer.
7. The light-emitting diode epitaxial wafer as claimed in any one of claims 1 to 3, wherein the doping concentration of n-type impurities in the GaN filling layer is 1E18-6E18/cm3。
8. A preparation method of a light emitting diode epitaxial wafer is characterized by comprising the following steps:
providing a substrate;
growing a GaN buffer layer on the substrate;
growing a nucleation layer on the GaN buffer layer, wherein n-type impurities are doped in the nucleation layer;
growing a GaN filling layer on the nucleating layer, wherein n-type impurities are doped in the GaN filling layer, and the doping concentration of the n-type impurities in the GaN filling layer is greater than that of the n-type impurities in the nucleating layer;
growing an n-type GaN layer on the GaN filling layer, wherein the doping concentration of n-type impurities in the nucleation layer is greater than that of the n-type impurities in the GaN filling layer, and the doping concentration of the n-type impurities in the n-type GaN layer is 2E 8-6E18/cm3；
Growing an active layer on the n-type GaN layer;
and growing a p-type GaN layer on the active layer.
9. The method for preparing the light-emitting diode epitaxial wafer as claimed in claim 8, wherein the growing the n-type GaN layer on the GaN filling layer comprises:
and introducing reaction gas into the reaction cavity and introducing a Si source discontinuously, and growing an n-type GaN layer on the GaN filling layer.
10. The method for preparing the light-emitting diode epitaxial wafer according to claim 9, wherein the Si source with the flow rate of 40-80 is introduced into the reaction chamber for 180-300 s each time.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9805086D0 (en) * 1997-03-12 1998-05-06 Hewlett Packard Co Light emitting device
CN105932118A (en) * 2016-06-13 2016-09-07 湘能华磊光电股份有限公司 LED epitaxial growth method for improving hole injection
CN106098874A (en) * 2016-07-29 2016-11-09 华灿光电（浙江）有限公司 The epitaxial wafer of a kind of light emitting diode and preparation method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9805086D0 (en) * 1997-03-12 1998-05-06 Hewlett Packard Co Light emitting device
CN105932118A (en) * 2016-06-13 2016-09-07 湘能华磊光电股份有限公司 LED epitaxial growth method for improving hole injection
CN106098874A (en) * 2016-07-29 2016-11-09 华灿光电（浙江）有限公司 The epitaxial wafer of a kind of light emitting diode and preparation method

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