CN109473511B - Gallium nitride-based light emitting diode epitaxial wafer and growth method thereof - Google Patents

Gallium nitride-based light emitting diode epitaxial wafer and growth method thereof Download PDF

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CN109473511B
CN109473511B CN201811063800.2A CN201811063800A CN109473511B CN 109473511 B CN109473511 B CN 109473511B CN 201811063800 A CN201811063800 A CN 201811063800A CN 109473511 B CN109473511 B CN 109473511B
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semiconductor layer
magnesium
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gallium nitride
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CN109473511A (en
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王倩
洪威威
陆香花
周飚
胡加辉
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HC Semitek Suzhou Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier 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
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
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    • H01L21/67253—Process monitoring, e.g. flow or thickness monitoring
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier 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 with at least one potential-jump barrier or surface barrier 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

Abstract

The invention discloses a gallium nitride-based light emitting diode epitaxial wafer and a growth method thereof, belonging to the technical field of semiconductors. The growth method comprises the following steps: providing a substrate; growing an N-type semiconductor layer on the substrate; growing an active layer on the N-type semiconductor layer; growing a first P-type semiconductor layer on the active layer in a growth atmosphere formed of hydrogen; growing a second P-type semiconductor layer on the first P-type semiconductor layer in a growth atmosphere formed of nitrogen; the first P-type semiconductor layer and the second P-type semiconductor layer respectively comprise a plurality of magnesium nitride layers and a plurality of magnesium-doped gallium nitride layers, and the magnesium nitride layers and the magnesium-doped gallium nitride layers are alternately stacked. The invention can improve the hole concentration in the P-type semiconductor layer and finally improve the luminous efficiency of the LED.

Description

Gallium nitride-based light emitting diode epitaxial wafer and growth method thereof
Technical Field
The invention relates to the technical field of semiconductors, in particular to a gallium nitride-based light emitting diode epitaxial wafer and a growth method thereof.
Background
A Light Emitting Diode (LED) is a semiconductor electronic component capable of Emitting Light. With the rapid development of the LED industry, LEDs are widely used in the fields of traffic lights, street lamps, landscape lamps, lighting, backlight sources, etc., and the requirements for the LED brightness are increasing. The epitaxial wafer is a primary finished product in the LED preparation process, and a plurality of experts and scholars of the LED realize the improvement of the LED brightness by adjusting the structure of the epitaxial wafer.
Gallium nitride (GaN) has good thermal conductivity, and also has excellent characteristics of high temperature resistance, acid and alkali resistance, high hardness and the like, so that gallium nitride (GaN) based LEDs are receiving more and more attention and research. The conventional gallium nitride-based LED includes a substrate, an N-type semiconductor layer, an active layer, and a P-type semiconductor layer, which are sequentially stacked on the substrate. The P-type semiconductor layer is used for providing holes for carrying out compound luminescence, the N-type semiconductor layer is used for providing electrons for carrying out compound luminescence, the active layer is used for carrying out radiation compound luminescence of the electrons and the holes, and the substrate is used for providing a growth surface for the epitaxial material.
In the process of implementing the invention, the inventor finds that the prior art has at least the following problems:
since the radius of the magnesium atom is almost equal to that of the gallium atom, substitutional atoms are easily formed, and therefore, gallium nitride doped with magnesium is generally used for the P-type semiconductor layer. Theoretically, the doping concentration of magnesium element in the P-type semiconductor layer is positively correlated with the concentration of free holes in the P-type semiconductor layer. If the doping concentration of the magnesium element in the P-type semiconductor layer is low, the concentration of free holes in the P-type semiconductor layer is low, and the recombination luminescence of electrons and holes in the active layer can be limited, so that the luminous efficiency of the LED is low. Therefore, the doping concentration of magnesium element in the P-type semiconductor layer is generally high.
The problem of magnesium compensation can be caused by high doping concentration of magnesium element, a neutral complex is easily formed in the P-type semiconductor layer, the activation efficiency of magnesium is reduced, and a large number of point defects are generated, so that the crystal quality of the P-type semiconductor layer is poor, the concentration of free holes in the P-type semiconductor layer is influenced, the compound luminescence of electrons and holes in the active layer is limited, and the luminous efficiency of the LED is low. That is, the light emitting efficiency of the LED is restricted by the crystal quality of the P-type semiconductor layer and the activation efficiency of magnesium atoms in the P-type semiconductor layer.
However, the P-type semiconductor layer is generally grown in a growth atmosphere formed of a mixed gas of nitrogen and hydrogen. Hydrogen atoms in the hydrogen gas and magnesium atoms can form Mg-H bonds, so that the activation efficiency of magnesium is low; meanwhile, the crystal quality of the P-type semiconductor layer is poor under the growth atmosphere of nitrogen. Therefore, the concentration of free holes in the P-type semiconductor layer is low, which seriously affects the luminous efficiency of the LED.
Disclosure of Invention
The embodiment of the invention provides a gallium nitride-based light-emitting diode epitaxial wafer and a growth method thereof, which can solve the problem of low luminous efficiency of an LED (light-emitting diode) caused by low concentration of free holes in a P-type semiconductor layer in the prior art. The technical scheme is as follows:
in one aspect, an embodiment of the present invention provides a growth method of a gallium nitride-based light emitting diode epitaxial wafer, where the growth method includes:
providing a substrate;
growing an N-type semiconductor layer on the substrate;
growing an active layer on the N-type semiconductor layer;
growing a first P-type semiconductor layer on the active layer in a growth atmosphere formed of hydrogen;
growing a second P-type semiconductor layer on the first P-type semiconductor layer in a growth atmosphere formed of nitrogen;
the first P-type semiconductor layer and the second P-type semiconductor layer respectively comprise a plurality of magnesium nitride layers and a plurality of magnesium-doped gallium nitride layers, and the magnesium nitride layers and the magnesium-doped gallium nitride layers are alternately stacked.
Optionally, the number of magnesium nitride layers in the first P-type semiconductor layer is the same as the number of magnesium-doped gallium nitride layers in the first P-type semiconductor layer; the number of the magnesium nitride layers in the first P-type semiconductor layer is 5-10.
Optionally, the number of magnesium nitride layers in the second P-type semiconductor layer is the same as the number of magnesium-doped gallium nitride layers in the second P-type semiconductor layer; the number of the magnesium nitride layers in the second P-type semiconductor layer is 5-10.
Optionally, the thickness of the magnesium nitride layer is 1nm to 3 nm.
Optionally, the thickness of the magnesium-doped gallium nitride layer is 4nm to 7 nm.
Optionally, the doping concentration of the magnesium element in the magnesium-doped gallium nitride layer is 1020cm-3～3*1020cm-3。
Optionally, the sum of the thicknesses of the second P-type semiconductor layer and the first P-type semiconductor layer is 100nm to 200 nm.
Optionally, the growth conditions of the first P-type semiconductor layer are the same as the growth conditions of the second P-type semiconductor layer, and the growth conditions include a growth temperature and a growth pressure.
Preferably, the growth temperature of the first P-type semiconductor layer is 800-1000 ℃, and the growth pressure of the first P-type semiconductor layer is 200-600 torr.
In another aspect, an embodiment of the present invention provides a gallium nitride-based light emitting diode epitaxial wafer, including a substrate, an N-type semiconductor layer, an active layer, a first P-type semiconductor layer, and a second P-type semiconductor layer, the N-type semiconductor layer, the active layer, the first P-type semiconductor layer, and the second P-type semiconductor layer being sequentially stacked on the substrate, the first P-type semiconductor layer being grown in a growth atmosphere formed of hydrogen gas, the second P-type semiconductor layer being grown in a growth atmosphere formed of nitrogen gas; the first P-type semiconductor layer and the second P-type semiconductor layer respectively comprise a plurality of magnesium nitride layers and a plurality of magnesium-doped gallium nitride layers, and the magnesium nitride layers and the magnesium-doped gallium nitride layers are alternately stacked.
The technical scheme provided by the embodiment of the invention has the following beneficial effects:
the first P-type semiconductor layer is grown in the growth atmosphere formed by hydrogen, and the hydrogen has an etching effect, so that the first P-type semiconductor layer can be processed, the defect extending to the P-type semiconductor layer in the epitaxial growth process is effectively covered, and the crystal quality of the P-type semiconductor layer is greatly improved; and then growing the second P-type semiconductor layer in the growth atmosphere formed by nitrogen, so that the formation of Mg-H bonds between hydrogen atoms and magnesium atoms in the growth atmosphere formed by hydrogen can be avoided, namely the doping amount of magnesium in the P-type semiconductor layer is increased, namely the activation efficiency of magnesium in the P-type semiconductor layer is improved. The first P-type semiconductor layer and the second P-type semiconductor layer respectively improve the P-type semiconductor layer in terms of crystal quality of the P-type semiconductor layer and activation efficiency of magnesium atoms in the P-type semiconductor layer, so that the hole concentration in the P-type semiconductor layer can be effectively increased, and finally the luminous efficiency of the LED is improved. And the first P type semiconductor layer and the second P type semiconductor layer respectively comprise a plurality of magnesium nitride layers and a plurality of magnesium-doped gallium nitride layers which are alternately stacked, magnesium atoms form substitutional atoms in the gallium nitride, the substitutional atoms can be effectively doped in the P type semiconductor layer, the proportion of the magnesium atoms at the gallium position is improved, meanwhile, the filling type magnesium atoms are reduced, the magnesium atoms are prevented from existing in the P type semiconductor layer in the form of impurities, the crystal quality of the P type semiconductor layer is improved, and the light emitting efficiency of the LED is further improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a flowchart of a method for growing an epitaxial wafer of a gallium nitride-based light emitting diode according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an epitaxial wafer of a gallium nitride-based light emitting diode according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of the first P-type semiconductor layer and the second P-type semiconductor layer according to an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The embodiment of the invention provides a growth method of a gallium nitride-based light-emitting diode epitaxial wafer. Fig. 1 is a flowchart of a method for growing a gan-based led epitaxial wafer according to an embodiment of the present invention. Referring to fig. 1, the growing method includes:
step 101: a substrate is provided.
Specifically, the material of the substrate may be sapphire (aluminum oxide is a main material), such as sapphire having a crystal orientation of [0001 ].
Specifically, the step 101 may include:
controlling the temperature to be 1000-1200 ℃ (preferably 1100 ℃), and annealing the substrate for 1-10 minutes (preferably 5 minutes) in a hydrogen atmosphere;
the substrate is subjected to a nitridation process.
The surface of the substrate is cleaned through the steps, impurities are prevented from being doped into the epitaxial wafer, and the growth quality of the epitaxial wafer is improved.
Step 102: an N-type semiconductor layer is grown on a substrate.
Specifically, the material of the N-type semiconductor layer may be N-type doped (e.g., silicon) gallium nitride.
Further, the thickness of the N-type semiconductor layer may be 1 μm to 5 μm, preferably 3 μm; the doping concentration of the N-type dopant in the N-type semiconductor layer may be 1018cm-3～1019cm-3Preferably 5 x 1018cm-3。
Specifically, this step 102 may include:
an N-type semiconductor layer is grown on a substrate under a controlled temperature of 1000 to 1200 deg.C (preferably 1100 deg.C) and a pressure of 100to 500torr (preferably 300 torr).
Optionally, before step 102, the preparation method may include:
a Physical Vapor Deposition (PVD) technique is used to form a buffer layer on a substrate.
Accordingly, an N-type semiconductor layer is grown on the buffer layer.
Stress and defects generated by lattice mismatch between the substrate material and the gallium nitride are relieved by arranging the buffer layer, and a nucleation center is provided for epitaxial growth of the gallium nitride material.
Specifically, the buffer layer may be made of aluminum nitride or aluminum gallium nitride.
Specifically, forming a buffer layer on a substrate using PVD techniques may include:
the temperature is controlled to be 400-800 ℃ (preferably 600 ℃), the pressure is controlled to be 4-6 torr (preferably 5torr), the sputtering power is 3000-5000W (preferably 4000W), and a buffer layer is formed on the substrate by adopting the magnetron sputtering technology.
Preferably, after forming the buffer layer on the substrate using the PVD technique, the preparation method may further include:
and growing an undoped gallium nitride layer on the buffer layer by using an MOCVD (metal organic chemical vapor deposition) technology.
Accordingly, an N-type semiconductor layer is grown on the undoped gallium nitride layer.
Stress and defects generated by lattice mismatch between a substrate material and gallium nitride are further relieved by arranging the undoped gallium nitride layer, and a growth surface with good crystal quality is provided for the main body structure of the epitaxial wafer.
In the specific implementation, firstly, the longitudinal growth of gallium nitride is carried out on the buffer layer, and a plurality of mutually independent three-dimensional island-shaped structures called three-dimensional nucleation layers are formed; then, transverse growth of gallium nitride is carried out on all the three-dimensional island structures and among the three-dimensional island structures to form a two-dimensional plane structure which is called a two-dimensional recovery layer; and finally, growing a thicker gallium nitride layer called an intrinsic gallium nitride layer on the two-dimensional growth layer at a high temperature. The three-dimensional nucleation layer, two-dimensional recovery layer, and intrinsic gallium nitride layer are collectively referred to as undoped gallium nitride layer in this embodiment.
Further, the thickness of the undoped gallium nitride layer may be 1 μm to 5 μm, preferably 3 μm.
Specifically, growing the undoped gallium nitride layer on the buffer layer by using the MOCVD technique may include:
an undoped gallium nitride layer is grown on the buffer layer at a temperature of 1000 ℃ to 1100 ℃ (preferably 1050 ℃) and a pressure of 100torr to 500torr (preferably 300 torr).
Step 103: an active layer is grown on the N-type semiconductor layer.
Specifically, the active layer may include a plurality of quantum wells and a plurality of quantum barriers, which are alternately stacked; the quantum well material may be indium gallium nitride (InGaN), such as InxGa1-xN, 0 < x < 1, and gallium nitride can be used as the material of the quantum barrier.
Further, the thickness of the quantum well may be 2nm to 3nm, preferably 2.5 nm; the thickness of the quantum barrier can be 9 nm-20 nm, preferably 15 nm; the number of quantum wells is the same as the number of quantum barriers, and the number of quantum barriers may be 5to 11, preferably 8.
Specifically, the step 103 may include:
growing an active layer on the N-type semiconductor layer; wherein the growth temperature of the quantum well is 720 ℃ to 829 ℃ (preferably 760 ℃), and the pressure is 100torr to 500torr (preferably 300 torr); the growth temperature of the quantum barrier is 850 to 959 deg.C (preferably 900 deg.C), and the pressure is 100to 500torr (preferably 300 torr).
Optionally, before step 103, the preparation method may comprise:
and growing a stress release layer on the N-type semiconductor layer by using an MOCVD (metal organic chemical vapor deposition) technology.
Accordingly, an active layer is grown on the stress relieving layer.
Stress generated by lattice mismatch between sapphire and gallium nitride is released by arranging the stress release layer, so that the crystal quality of the active layer is improved, electrons and holes can radiate and emit light in the active layer in a composite manner, the internal quantum efficiency of the LED is improved, and the luminous efficiency of the LED is improved.
Specifically, the material of the stress release layer can be gallium indium aluminum nitride (AlInGaN), so that the stress generated by lattice mismatch of sapphire and gallium nitride can be effectively released, the crystal quality of an epitaxial wafer is improved, and the luminous efficiency of the LED is improved.
Preferably, the molar content of the aluminum component in the stress release layer may be less than or equal to 0.2, and the molar content of the indium component in the stress release layer may be less than or equal to 0.05, so as to avoid causing adverse effects.
Further, the thickness of the stress release layer may be 50nm to 500nm, preferably 300 nm.
Specifically, growing the stress release layer on the N-type semiconductor layer by using the MOCVD technique may include:
the temperature is controlled to be 800 ℃ to 1100 ℃ (preferably 950 ℃) and the pressure is controlled to be 100torr to 500torr (preferably 300torr), and the stress release layer is grown on the N-type semiconductor layer.
Step 104: a first P-type semiconductor layer is grown on the active layer in a growth atmosphere formed of hydrogen.
Step 105: a second P-type semiconductor layer is grown on the first P-type semiconductor layer in a growth atmosphere formed of nitrogen.
The first P-type semiconductor layer and the second P-type semiconductor layer respectively comprise a plurality of magnesium nitride layers and a plurality of magnesium-doped gallium nitride layers, and the magnesium nitride layers and the magnesium-doped gallium nitride layers are alternately stacked.
According to the embodiment of the invention, the first P type semiconductor layer is grown in the growth atmosphere formed by hydrogen, and the hydrogen has an etching effect, so that the first P type semiconductor layer can be processed, the defect extending to the P type semiconductor layer in the epitaxial growth process is effectively covered, and the crystal quality of the P type semiconductor layer is greatly improved; and then growing the second P-type semiconductor layer in the growth atmosphere formed by nitrogen, so that the formation of Mg-H bonds between hydrogen atoms and magnesium atoms in the growth atmosphere formed by hydrogen can be avoided, namely the doping amount of magnesium in the P-type semiconductor layer is increased, namely the activation efficiency of magnesium in the P-type semiconductor layer is improved. The first P-type semiconductor layer and the second P-type semiconductor layer respectively improve the P-type semiconductor layer in terms of crystal quality of the P-type semiconductor layer and activation efficiency of magnesium atoms in the P-type semiconductor layer, so that the hole concentration in the P-type semiconductor layer can be effectively increased, and finally the luminous efficiency of the LED is improved. And the first P type semiconductor layer and the second P type semiconductor layer respectively comprise a plurality of magnesium nitride layers and a plurality of magnesium-doped gallium nitride layers which are alternately stacked, magnesium atoms form substitutional atoms in the gallium nitride, the substitutional atoms can be effectively doped in the P type semiconductor layer, the proportion of the magnesium atoms at the gallium position is improved, meanwhile, the filling type magnesium atoms are reduced, the magnesium atoms are prevented from existing in the P type semiconductor layer in the form of impurities, the crystal quality of the P type semiconductor layer is improved, and the light emitting efficiency of the LED is further improved.
Optionally, the number of magnesium nitride layers in the first P-type semiconductor layer is the same as the number of magnesium-doped gallium nitride layers in the first P-type semiconductor layer; the number of magnesium nitride layers in the first P-type semiconductor layer may be 5to 10, preferably 8.
If the number of the magnesium nitride layers and the magnesium-doped gallium nitride layers in the first P-type semiconductor is less than 5, the crystal quality of the P-type semiconductor layer may not be effectively improved due to the small number of the magnesium nitride layers and the magnesium-doped gallium nitride layers in the first P-type semiconductor; if the number of the magnesium nitride layer and the magnesium-doped gallium nitride layer in the first P-type semiconductor is more than 10, the thickness of the P-type semiconductor is thicker, the light absorption of the P-type semiconductor layer is serious, and the light extraction efficiency of the LED is affected.
Optionally, the number of magnesium nitride layers in the second P-type semiconductor layer is the same as the number of magnesium-doped gallium nitride layers in the second P-type semiconductor layer; the number of magnesium nitride layers in the second P-type semiconductor layer may be 5to 10, preferably 8.
If the number of the magnesium nitride layer and the magnesium-doped gallium nitride layer in the second P-type semiconductor is less than 5, the crystal quality of the P-type semiconductor layer may not be effectively improved due to the small number of the magnesium nitride layer and the magnesium-doped gallium nitride layer in the second P-type semiconductor; if the number of the magnesium nitride layer and the magnesium-doped gallium nitride layer in the second P-type semiconductor is greater than 10, the complexity of the process and the implementation cost may be increased due to the greater number of the magnesium nitride layer and the magnesium-doped gallium nitride layer in the second P-type semiconductor.
Alternatively, the magnesium nitride layer may have a thickness of 1nm to 3nm, preferably 2 nm.
If the thickness of the magnesium nitride layer is less than 1nm, the concentration of effective holes in the P-type semiconductor layer cannot be effectively increased due to the fact that the magnesium nitride layer is thin, and the light-emitting efficiency of the LED is not obviously improved; if the thickness of the magnesium nitride layer is greater than 3nm, the crystal structure of the P-type semiconductor layer may be affected by a large amount of Mg due to the relatively thick magnesium nitride layer.
Alternatively, the thickness of the magnesium-doped gallium nitride layer may be 4nm to 7nm, preferably 5.5 nm.
If the thickness of the magnesium-doped gallium nitride layer is less than 4nm, the crystal structure of the P-type semiconductor layer may be affected due to the thinness of the magnesium-doped gallium nitride layer; if the thickness of the magnesium-doped gallium nitride layer is greater than 7nm, the magnesium-doped gallium nitride layer is too thick to affect the matching with the magnesium nitride layer, so that the concentration of effective holes in the P-type semiconductor layer cannot be effectively increased, and the improvement effect of the luminous efficiency of the LED is not obvious.
Optionally nitrogen doped with magnesiumThe doping concentration of magnesium element in the gallium nitride layer may be 1020cm-3～3*1020cm-3Preferably 2 x 1020cm-3。
If the doping concentration of magnesium element in the magnesium-doped gallium nitride layer is less than 1020cm-3The crystal lattice mismatch between the magnesium nitride layer and the magnesium doped gallium nitride layer may be caused by the small doping concentration of the magnesium element in the magnesium doped gallium nitride layer, so that the crystal quality of the P-type semiconductor layer is reduced; if the doping concentration of magnesium element in the magnesium-doped gallium nitride layer is more than 3 x 1020cm-3There is a possibility that the impurity in the P-type semiconductor layer is too much due to the large doping concentration of the magnesium element in the magnesium-doped gallium nitride layer, and the crystal quality of the P-type semiconductor layer is lowered.
Alternatively, the sum of the thicknesses of the first and second P-type semiconductor layers may be 100nm to 200 nm.
If the sum of the thicknesses of the first and second P-type semiconductor layers is less than 100nm, a sufficient number of holes may not be provided for the active layer due to the small sum of the thicknesses of the first and second P-type semiconductor layers, which may affect the light emitting efficiency of the LED; if the sum of the thicknesses of the first and second P-type semiconductor layers is greater than 200nm, the P-type semiconductor layer may be too thick, and light absorption of the P-type semiconductor layer is severe, which may affect the light emitting efficiency of the LED.
Alternatively, the growth conditions of the first P-type semiconductor layer and the second P-type semiconductor layer may be the same, and the growth conditions include a growth temperature and a growth pressure. The same growth conditions are adopted, and the realization is more convenient.
Preferably, the growth temperature of the first P-type semiconductor layer may be 800 to 1000 ℃, and the growth pressure of the first P-type semiconductor layer may be 200to 600 torr. The quality of the formed P-type semiconductor layer is better by matching with the growth temperature and the growth pressure.
Optionally, before step 104, the preparation method may further include:
and growing an electron blocking layer on the active layer by using an MOCVD (metal organic chemical vapor deposition) technology.
Accordingly, a P-type semiconductor layer is grown on the electron blocking layer.
The electron blocking layer is arranged to prevent electrons from jumping into the hole providing layer to be non-radiatively combined with holes, so that the luminous efficiency of the LED is reduced.
Specifically, the electron blocking layer may be made of P-type doped aluminum gallium nitride (AlGaN) such as AlyGa1-yN，0.1＜y＜0.5。
Further, the thickness of the electron blocking layer may be 20nm to 100nm, preferably 60 nm.
Specifically, growing the electron blocking layer on the active layer by using the MOCVD technology may include:
the electron blocking layer is grown on the active layer at a controlled temperature of 700 to 1000 deg.C (preferably 850 deg.C) and a pressure of 100to 500torr (preferably 300 torr).
Preferably, before growing the electron blocking layer on the active layer by using the MOCVD technique, the preparation method may further include:
and growing a low-temperature P-type layer on the active layer by using an MOCVD (metal organic chemical vapor deposition) technology.
Accordingly, an electron blocking layer is grown on the low temperature P-type layer.
By arranging the low-temperature P-type layer, the phenomenon that indium atoms in the active layer are separated out due to the high growth temperature of the electron blocking layer and the luminous efficiency of the light-emitting diode is influenced is avoided.
Specifically, the material of the low-temperature P-type layer may be P-type doped gallium nitride.
Further, the thickness of the low-temperature P-type layer may be 50nm to 100nm, preferably 75 nm; the doping concentration of the P-type dopant in the low-temperature P-type layer may be 1018/cm3～1020/cm3Preferably 1019/cm3。
Specifically, growing the low-temperature P-type layer on the active layer by using the MOCVD technology may include:
the temperature is controlled to be 600 ℃ to 800 ℃ (preferably 700 ℃) and the pressure is controlled to be 200torr to 500torr (preferably 350torr), and the low-temperature P-type layer is grown on the active layer.
Optionally, after step 105, the preparation method may further include:
and growing a contact layer on the P-type semiconductor layer by using an MOCVD (metal organic chemical vapor deposition) technology.
The contact layer is arranged to form ohmic contact with an electrode or a transparent conductive film formed in a chip manufacturing process.
Specifically, the P-type contact layer may be made of P-type doped indium gallium nitride.
Further, the thickness of the P-type contact layer may be 5nm to 100nm, preferably 50 nm; the doping concentration of the P-type dopant in the P-type contact layer may be 1021/cm3～1022/cm3Preferably 5 x 1021/cm3。
Specifically, growing the contact layer on the P-type semiconductor layer by using the MOCVD technology may include:
the contact layer is grown on the P-type semiconductor layer at a temperature of 850 to 1050 deg.C (preferably 950 deg.C) and a pressure of 100to 300torr (preferably 200 torr).
After the completion of the epitaxial growth, the temperature is lowered to 650 to 850 ℃ (preferably 750 ℃), the epitaxial wafer is annealed in a nitrogen atmosphere for 5to 15 minutes (preferably 10 minutes), and then the temperature of the epitaxial wafer is lowered to room temperature.
The control of the temperature and the pressure both refer to the control of the temperature and the pressure in a reaction chamber for growing the epitaxial wafer, and specifically refer to the reaction chamber of a Metal-organic Chemical Vapor Deposition (MOCVD) device. During implementation, trimethyl gallium or triethyl gallium is used as a gallium source, high-purity ammonia gas is used as a nitrogen source, trimethyl indium is used as an indium source, trimethyl aluminum is used as an aluminum source, silane is used as an N-type dopant, and magnesium diclocide is used as a P-type dopant.
The embodiment of the invention provides a gallium nitride-based light emitting diode epitaxial wafer which is suitable for being grown by adopting the growth method of the gallium nitride-based light emitting diode epitaxial wafer shown in figure 1. Fig. 2 is a schematic structural diagram of a gan-based led epitaxial wafer according to an embodiment of the present invention. Referring to fig. 2, the gan-based light emitting diode epitaxial wafer substrate 10, the N-type semiconductor layer 20, the active layer 30, the first P-type semiconductor layer 41 and the second P-type semiconductor layer 42 are sequentially stacked on the substrate 10, and the N-type semiconductor layer 20, the active layer 30, the first P-type semiconductor layer 41 and the second P-type semiconductor layer 42 are sequentially stacked on the substrate 10.
In the present embodiment, the first P-type semiconductor layer 41 is grown in a growth atmosphere formed of hydrogen, and the second P-type semiconductor layer 42 is grown in a growth atmosphere formed of nitrogen. Fig. 3 is a schematic structural diagram of the first P-type semiconductor layer and the second P-type semiconductor layer according to an embodiment of the invention. Referring to fig. 3, each of the first and second P-type semiconductor layers 41 and 42 includes a plurality of magnesium nitride layers 43 and a plurality of magnesium-doped gallium nitride layers 44, and the plurality of magnesium nitride layers 43 and the plurality of magnesium-doped gallium nitride layers 44 are alternately stacked.
Alternatively, as shown in fig. 2, the light emitting diode epitaxial wafer may further include a buffer layer 51, and the buffer layer 51 is disposed between the substrate 10 and the N-type semiconductor layer 20.
Preferably, as shown in fig. 2, the light emitting diode epitaxial wafer may further include an undoped gallium nitride layer 52, and the undoped gallium nitride layer 52 is disposed between the buffer layer 51 and the N-type semiconductor layer 20.
Optionally, as shown in fig. 2, the light emitting diode epitaxial wafer may further include a stress relief layer 60, and the stress relief layer 60 is disposed between the N-type semiconductor layer 20 and the active layer 30.
Optionally, as shown in fig. 2, the light emitting diode epitaxial wafer may further include an electron blocking layer 71, and the electron blocking layer 71 is disposed between the active layer 30 and the first P-type semiconductor layer 41.
Preferably, as shown in fig. 2, the light emitting diode epitaxial wafer may further include a low temperature P-type layer 72, and the low temperature P-type layer 72 is disposed between the active layer 30 and the electron blocking layer 71.
Optionally, as shown in fig. 2, the light emitting diode epitaxial wafer may further include a contact layer 80, and the contact layer 80 is disposed on the second P-type semiconductor layer 42.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (8)

1. A growth method of a gallium nitride-based light emitting diode epitaxial wafer is characterized by comprising the following steps:
providing a substrate;
growing an N-type semiconductor layer on the substrate;
growing an active layer on the N-type semiconductor layer;
growing a first P-type semiconductor layer on the active layer in a growth atmosphere formed of hydrogen;
growing a second P-type semiconductor layer on the first P-type semiconductor layer in a growth atmosphere formed of nitrogen;
the first P-type semiconductor layer and the second P-type semiconductor layer respectively comprise a plurality of magnesium nitride layers and a plurality of magnesium-doped gallium nitride layers, and the magnesium nitride layers and the magnesium-doped gallium nitride layers are alternately stacked; the doping concentration of the magnesium element in the magnesium-doped gallium nitride layer is 1020cm-3～3*1020cm-3And the growth conditions of the second P-type semiconductor layer are the same as those of the first P-type semiconductor layer, and the growth conditions comprise growth temperature and growth pressure.
2. The growth method according to claim 1, wherein the number of magnesium nitride layers in the first P-type semiconductor layer is the same as the number of magnesium-doped gallium nitride layers in the first P-type semiconductor layer; the number of the magnesium nitride layers in the first P-type semiconductor layer is 5-10.
3. The growth method according to claim 1 or 2, wherein the number of magnesium nitride layers in the second P-type semiconductor layer is the same as the number of magnesium-doped gallium nitride layers in the second P-type semiconductor layer; the number of the magnesium nitride layers in the second P-type semiconductor layer is 5-10.
4. The growth method according to claim 1 or 2, wherein the thickness of the magnesium nitride layer is 1nm to 3 nm.
5. The growth method according to claim 1 or 2, wherein the thickness of the magnesium-doped gallium nitride layer is 4nm to 7 nm.
6. The growth method according to claim 1 or 2, wherein the sum of the thicknesses of the first P-type semiconductor layer and the second P-type semiconductor layer is 100nm to 200 nm.
7. The growth method according to claim 1 or 2, wherein the growth temperature of the first P-type semiconductor layer is 800 ℃ to 1000 ℃ and the growth pressure of the first P-type semiconductor layer is 200torr to 600 torr.
8. A gallium nitride-based light emitting diode epitaxial wafer is characterized by comprising a substrate, an N-type semiconductor layer, an active layer, a first P-type semiconductor layer and a second P-type semiconductor layer, wherein the N-type semiconductor layer, the active layer, the first P-type semiconductor layer and the second P-type semiconductor layer are sequentially laminated on the substrate, the first P-type semiconductor layer grows in a growth atmosphere formed by hydrogen, and the second P-type semiconductor layer grows in a growth atmosphere formed by nitrogen; the first P-type semiconductor layer and the second P-type semiconductor layer respectively comprise a plurality of magnesium nitride layers and a plurality of magnesium-doped gallium nitride layers, and the magnesium nitride layers and the magnesium-doped gallium nitride layers are alternately stacked; the doping concentration of the magnesium element in the magnesium-doped gallium nitride layer is 1020cm-3～3*1020cm-3And the growth conditions of the second P-type semiconductor layer are the same as those of the first P-type semiconductor layer, and the growth conditions comprise growth temperature and growth pressure.
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