CN113161453B - Light emitting diode epitaxial wafer and manufacturing method thereof - Google Patents

Light emitting diode epitaxial wafer and manufacturing method thereof Download PDF

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CN113161453B
CN113161453B CN202110104662.3A CN202110104662A CN113161453B CN 113161453 B CN113161453 B CN 113161453B CN 202110104662 A CN202110104662 A CN 202110104662A CN 113161453 B CN113161453 B CN 113161453B
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electron blocking
type layer
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CN113161453A (en
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姚振
从颖
董彬忠
李鹏
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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 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
    • H01L33/14—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 carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
    • H01L33/145—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 carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure with a current-blocking structure
    • 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
    • H01L33/025—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
    • H01L33/02—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 manufacturing method thereof, and belongs to the technical field of semiconductors. The light-emitting diode epitaxial wafer comprises a substrate, and a low-temperature buffer layer, a high-temperature buffer layer, an N-type layer and an active layer which are sequentially stacked on the substrate, and further comprises an electron blocking layer and a P-type layer which are sequentially stacked on the active layer and alternately grow in multiple periods, wherein each electron blocking layer is an AlGaN layer, and along the stacking direction of the epitaxial wafer, the Al component in the electron blocking layer in each period is gradually reduced, the thickness is gradually reduced, and the doping concentration of Mg in the P-type layer in each period is gradually increased. The light-emitting diode epitaxial wafer can increase the overlapping degree of wave functions of electrons and holes on spatial distribution, so that the internal quantum efficiency of an LED can be improved.

Description

Light emitting diode epitaxial wafer and manufacturing method thereof
Technical Field
The disclosure relates to the technical field of semiconductors, and in particular relates to a light emitting diode epitaxial wafer and a manufacturing method thereof.
Background
A Light Emitting Diode (LED) is a semiconductor electronic component capable of Emitting Light. As a novel high-efficiency, environment-friendly and green solid-state illumination light source, the LED is a new generation light source with a wide prospect, and is rapidly and widely applied to the fields such as traffic signal lamps, automobile interior and exterior lamps, urban landscape illumination, indoor and outdoor display screens, small-distance display screens and the like.
Generally, GaN-based LEDs are epitaxially grown on a sapphire substrate. The traditional GaN-based LED epitaxial structure generally adopts an InGaN/GaN superlattice structure as an active layer. However, a large lattice mismatch exists between the InGaN layer and the GaN layer, resulting in a large compressive stress between the InGaN layer and the GaN layer. The piezoelectric polarization electric field is generated by the pressure stress, so that the overlapping of electron and hole wave functions is reduced, the internal quantum efficiency is reduced, and the luminous efficiency of the LED is influenced.
Disclosure of Invention
The embodiment of the disclosure provides a light emitting diode epitaxial wafer and a manufacturing method thereof, which can increase the overlapping degree of wave functions of electrons and holes on spatial distribution and improve the internal quantum efficiency of an LED. The technical scheme is as follows:
in one aspect, a light emitting diode epitaxial wafer is provided, the light emitting diode epitaxial wafer comprises a substrate, and a low-temperature buffer layer, a high-temperature buffer layer, an N-type layer and an active layer which are sequentially laminated on the substrate,
the light-emitting diode epitaxial wafer further comprises a plurality of electronic barrier layers and P-type layers which are sequentially stacked on the active layer and alternately grow in a periodic mode, each electronic barrier layer is an AlGaN layer, Al components in the electronic barrier layers in each period gradually decrease along the stacking direction of the epitaxial wafer, the thickness gradually decreases, and the doping concentration of Mg in the P-type layers in each period gradually increases.
Optionally, the variation range of the Al component in the electron blocking layers is 0.1-0.4.
Optionally, the reduction range of the Al component in the electron blocking layers is 0.05-0.25.
Optionally, the thickness of the electron blocking layers varies from 1nm to 20 nm.
Optionally, the thickness of the electron blocking layers is reduced by 5-15 nm.
Optionally, the doping concentration of Mg in a plurality of the P-type layers varies in a range of 5 x 1017cm-3~6*1020cm-3。
Optionally, the thickness of a plurality of the P-type layers is gradually reduced.
In another aspect, a method for manufacturing a light emitting diode epitaxial wafer is provided, the method comprising:
providing a substrate;
sequentially growing a low-temperature buffer layer, a high-temperature buffer layer, an N-type layer and an active layer on the substrate;
and growing a plurality of electron blocking layers and P-type layers which alternately grow in cycles on the active layer, wherein each electron blocking layer is an AlGaN layer, the Al component in the electron blocking layer in each cycle is gradually reduced, the thickness is gradually reduced, and the doping concentration of Mg in the P-type layer in each cycle is gradually increased along the stacking direction of the epitaxial wafer.
Optionally, the growth temperature of each of the electron blocking layers is 930-970 ℃, and the growth pressure is 100-200 torr.
Optionally, the growth temperature of the P-type layers is 940-980 ℃, and the growth pressure is 200-600 torr.
The technical scheme provided by the embodiment of the disclosure has the following beneficial effects:
the method comprises the step of setting a plurality of electron blocking layers and P-type layers which are alternately grown in a periodic mode, wherein the Al component in the electron blocking layers in each period is gradually reduced and the thickness is gradually reduced along the lamination direction of the epitaxial wafer. That is, in the direction from the active layer to the P-type layer, the Al composition in the electron blocking layer near the active layer is the highest and the thickness is the thickest, so that most of electrons leaking from the active layer can be blocked, and the electrons can be prevented from overflowing. And the electron blocking layers in a plurality of subsequent periods need to block fewer electrons, so that the Al component and the thickness can be gradually reduced and gradually reduced, and the leaked small part of electrons can be further blocked, so that the effect of better preventing the overflow of the electrons is achieved. Meanwhile, the blocking of holes provided by the P-type layer can be reduced, and the injection of the holes is favorably improved. Further, the doping concentration of Mg in the P-type layer of each period gradually increases, that is, in the direction from the active layer to the P-type layer, the doping concentration of Mg in the P-type layer close to the active layer is the highest, so that more holes are provided, and the P-type layer and the electrons are radiated and recombined in the active layer to emit light. And the arrangement of a plurality of P-type layers can provide the maximized number and concentration of holes so as to form larger hole potential energy flow, thereby greatly increasing the injection of the holes. Therefore, the adoption of the epitaxial structure can effectively increase the overlapping degree of wave functions of electrons and holes on spatial distribution, and further improve the internal quantum efficiency of the diode.
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 partial structural view of an epitaxial wafer of a light emitting diode 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, and as shown in fig. 1, the led epitaxial wafer includes a substrate 1, and a low-temperature buffer layer 2, a high-temperature buffer layer 3, an N-type layer 4, and an active layer 5 sequentially stacked on the substrate 1.
The light emitting diode epitaxial wafer further comprises a plurality of periodically and alternately grown electron blocking layers 6 and P-type layers 7 which are sequentially laminated on the active layer 5. Each electron blocking layer 6 is an AlGaN layer, and along the stacking direction of the epitaxial wafer, the Al component in the electron blocking layer 6 in each period gradually decreases, the thickness gradually decreases, and the doping concentration of Mg in the P-type layer 7 in each period gradually increases.
The embodiment of the disclosure arranges a plurality of electron blocking layers and P-type layers which are alternately grown in a periodic manner, wherein the Al component in the electron blocking layers in each period is gradually reduced and the thickness is gradually reduced along the lamination direction of the epitaxial wafer. That is, in the direction from the active layer to the P-type layer, the Al composition in the electron blocking layer near the active layer is the highest and the thickness is the thickest, so that most of electrons leaking from the active layer can be blocked, and the electrons can be prevented from overflowing. And the electron blocking layers in a plurality of subsequent periods need to block fewer electrons, so that the Al component and the thickness can be gradually reduced and gradually reduced, and the leaked small part of electrons can be further blocked, so that the effect of better preventing the overflow of the electrons is achieved. Meanwhile, the blocking of holes provided by the P-type layer can be reduced, and the injection of the holes is favorably improved. Further, the doping concentration of Mg in the P-type layer of each period gradually increases, that is, the doping concentration of Mg in the P-type layer close to the active layer is the highest in the direction from the active layer to the P-type layer, so that more holes are provided, and the P-type layer and the electrons are radiated and recombined in the active layer to emit light. And the arrangement of a plurality of P-type layers can provide the maximized number and concentration of holes so as to form larger hole potential energy flow, thereby greatly increasing the injection of the holes. Therefore, the adoption of the epitaxial structure can effectively increase the overlapping degree of wave functions of electrons and holes on spatial distribution, and further improve the internal quantum efficiency of the diode.
Optionally, the light emitting diode epitaxial wafer comprises m periodically and alternately grown electron blocking layers 6 and P-type layers 7 which are sequentially stacked on the active layer 5, wherein m is larger than or equal to 2 and smaller than or equal to 6.
If the number of m is too large, the growth process is complicated, and the growth period is slow. If the number of m is too small, the effect of blocking electrons many times cannot be achieved, and thus the effect of preventing the overflow of electrons cannot be effectively achieved.
Optionally, the Al composition in the electron blocking layers 6 varies in a range of 0.1 to 0.4.
If the content of the Al component in the electron blocking layer is too high, holes may be blocked, and injection of holes may be adversely affected. If the content of the Al component in the electron blocking layer is too low, the electron blocking layer cannot have a good blocking effect on electrons, and the electrons are prevented from overflowing.
Illustratively, the Al composition in the plurality of electron blocking layers 6 gradually decreases from 0.4 to 0.1.
Optionally, the reduction range of the Al component in the electron blocking layers 6 is 0.05-0.25.
If the reduction range of the Al component in the electron blocking layers 6 is too large, the number of layers of the electron blocking layers 6 to be grown is small, and thus electrons cannot be blocked many times, which cannot prevent the electrons from overflowing well. If the reduction range of the Al component in the electron blocking layers 6 is too small, the number of layers of the electron blocking layers 6 to be grown is large on the premise of ensuring the effect of preventing the electron overflow, and the growth period is long.
Optionally, the thickness of the electron blocking layers 6 varies from 1nm to 20 nm.
If the thickness of the electron blocking layer is too thick, holes are blocked, and the injection of holes is adversely affected. If the thickness of the electron blocking layer is too thin, the electron blocking layer cannot have a good blocking effect on electrons, and the electrons are prevented from overflowing.
Illustratively, the thickness of the plurality of electron blocking layers 6 is gradually reduced from 20nm to 1 nm.
Optionally, the thickness of the electron blocking layers is reduced by 5-15 nm.
If the reduction range of the thickness of the electron blocking layers 6 is too large, the number of layers of the electron blocking layers 6 to be grown is small, and electrons cannot be blocked many times, and thus, a good effect of preventing electron overflow cannot be obtained. If the reduction range of the thicknesses of the electron blocking layers 6 is too small, on the premise of ensuring the effect of preventing electron overflow, the number of layers of the electron blocking layers 6 to be grown is large, and the growth period is long.
Optionally, the P-type layer 7 is a Mg-doped GaN layer.
Optionally, the doping concentration of Mg in the plurality of P-type layers 7 varies in a range of 5 x 1017cm-3~6*1020cm-3。
If the doping concentration of Mg in the P-type layer 7 is too high, non-radiative recombination between some holes and leaking electrons is easily caused, thereby reducing the light emitting efficiency. If the doping concentration of Mg in the P-type layer is too low, the effect of effectively improving hole injection cannot be achieved.
Illustratively, the doping concentration of Mg in the P-type layers 7 is 5 × 1017cm-3Gradually increase to 6 x 1020cm-3。
Optionally, the doping concentration of Mg in the P-type layers 7 is increased by 5 × 1017cm-3~6.5*1020cm-3。
If the doping concentration of Mg in the P-type layers 7 is increased too much, the number of layers of the grown P-type layers 7 is small, and the effect of providing the maximum number and concentration of holes cannot be obtained. If the increase of the Mg doping concentration of the P-type layers 7 is too small, the number of layers of the P-type layers 7 to be grown is large on the premise of ensuring the number of the provided holes, and the growth period is long.
Optionally, the thicknesses of the P-type layers are gradually reduced, and the variation range of the thicknesses of the P-type layers 7 is 2-25 nm.
If the thickness of the P-type layer 7 per period is too thick, the P-type layer 7 absorbs light, thereby reducing the light emitting efficiency of the light emitting diode, and if the thickness of the P-type layer 7 per period is too thin, sufficient holes and electrons cannot be provided for radiative recombination light emission, thereby also reducing the light emitting efficiency of the light emitting diode.
Illustratively, the thickness of the plurality of P-type layers 7 is gradually reduced from 25nm to 2 nm.
Optionally, the thickness of the plurality of P-type layers 7 is reduced by 2-15 nm.
If the reduction in the thickness of the P-type layers 7 is too large, the number of layers of the grown P-type layers 7 is small, and the effect of providing the maximum number and concentration of holes cannot be obtained. If the reduction range of the thicknesses of the P-type layers 7 is too small, on the premise of ensuring the internal quantum efficiency, the number of layers of the P-type layers 7 to be grown is large, and the growth period is long.
Alternatively, the substrate 1 may be sapphire (Al as a main component)2O3) Substrate, preferably [0001]]Sapphire of crystal orientation.
Optionally, the low-temperature buffer layer 2 may be a GaN layer with a thickness of 15-30 nm.
Alternatively, the high temperature buffer layer 3 may be a GaN layer with a thickness of 2-3.5 um.
Optionally, the N-type layer 4 is a Si-doped GaN layer with a thickness of 2-3 um.
Alternatively, the active layer 5 includes a plurality of InGaN quantum well layers and GaN quantum barrier layers alternately grown in cycles. The number of cycles of the active layer 5 may be 5 to 11. The thickness of the InGaN quantum well layer is 2 nm-4 nm, and preferably 3.5 nm. The thickness of the GaN quantum barrier layer is 9 nm-20 nm, and the preferable thickness is 12 nm.
One specific implementation of the light emitting diode epitaxial wafer shown in fig. 1 includes: the light-emitting diode epitaxial wafer further comprises three periodically and alternately grown electron blocking layers 6 and P-type layers 7 which are sequentially laminated on the active layer 5. The electron blocking layer of each period is AlxGa1-xAnd x is more than or equal to 0.1 and less than or equal to 0.4.
Fig. 2 is a schematic partial structure diagram of an led epitaxial wafer according to an embodiment of the present disclosure, and as shown in fig. 2, the led epitaxial wafer includes a first electron blocking layer 61, a first P-type layer 71, a second electron blocking layer 62, a second P-type layer 72, a third electron blocking layer 63, and a third P-type layer 73, which are sequentially stacked on an active layer 5.
Wherein the first electron blocking layer 61 is Alx1Ga1-x1And x1 is more than or equal to 0.35 and less than or equal to 0.4 of the N layer. The thickness of the first electron blocking layer 61 is 10 to 20 nm. The second electron blocking layer 62 is Alx2Ga1-x2And x2 is more than or equal to 0.25 and less than or equal to 0.3 of the N layer. The thickness of the second electron blocking layer 62 is 5 to 15 nm. The third electron blocking layer 63 is Alx3Ga1-x3And x3 is more than or equal to 0.03 and less than or equal to 0.1. The thickness of the third electron blocking layer 63 is 1 to 6 nm.
The first P-type layer 71, the second P-type layer 72, and the third P-type layer 73 are all Mg-doped GaN layers. The doping concentration of Mg in the first P-type layer 71 is 5 x 1017cm-3~2*1018cm-3. The thickness of the first P type layer 71 is 15 to 25 nm. The doping concentration of Mg in the second P-type layer 72 is 5 x 1018cm-3~5*1019cm-3. The thickness of the second P type layer 72 is 10-20 nm. The doping concentration of Mg in the third P-type layer 73 is 1 x 1020cm-3~6*1020cm-3. The thickness of the third P-type layer 73 is 2-8 nm.
Compared with the chips manufactured in the prior art, the LED chip manufactured by the epitaxial wafer has the advantage that the light emitting efficiency of the LED chip is increased by 12%.
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, and as shown in fig. 3, the method for manufacturing includes:
step 301, a substrate is provided.
Step 302, growing a low-temperature buffer layer, a high-temperature buffer layer, an N-type layer and an active layer on the substrate in sequence.
Step 303, growing a plurality of electron blocking layers and P-type layers alternately grown in cycles on the active layer, wherein each electron blocking layer is an AlGaN layer, and along the stacking direction of the epitaxial wafer, the Al component in each cycle of electron blocking layer gradually decreases, the thickness gradually decreases, and the doping concentration of Mg in each cycle of P-type layer gradually increases.
The embodiment of the disclosure arranges a plurality of electron blocking layers and P-type layers which are alternately grown in a periodic manner, wherein the Al component in the electron blocking layers in each period is gradually reduced and the thickness is gradually reduced along the lamination direction of the epitaxial wafer. That is, in the direction from the active layer to the P-type layer, the Al composition in the electron blocking layer near the active layer is the highest and the thickness is the thickest, so that most of electrons leaking from the active layer can be blocked, and the electrons can be prevented from overflowing. And the electron blocking layers in a plurality of subsequent periods need to block fewer electrons, so that the Al component and the thickness can be gradually reduced and gradually reduced, and the leaked small part of electrons can be further blocked, so that the effect of better preventing the overflow of the electrons is achieved. Meanwhile, the blocking of holes provided by the P-type layer can be reduced, and the injection of the holes is favorably improved. Further, the doping concentration of Mg in the P-type layer of each period gradually increases, that is, the doping concentration of Mg in the P-type layer close to the active layer is the highest in the direction from the active layer to the P-type layer, so that more holes are provided, and the P-type layer and the electrons are radiated and recombined in the active layer to emit light. And the arrangement of a plurality of P-type layers can provide the maximized number and concentration of holes so as to form larger hole potential energy flow, thereby greatly increasing the injection of the holes. Therefore, the adoption of the epitaxial structure can effectively increase the overlapping degree of wave functions of electrons and holes on spatial distribution, and further improve the internal quantum efficiency of the diode.
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, and as shown in fig. 4, the method includes:
step 401, a substrate is provided.
The substrate can be a sapphire flat sheet substrate.
Further, step 401 may further include:
and processing the substrate at high temperature for 5-6 min in a hydrogen atmosphere. Wherein the temperature of the reaction chamber is 1000-1100 deg.C, and the pressure of the reaction chamber is controlled at 200-500 torr.
In this example, a Veeco K465i or C4 or RB MOCVD (Metal Organic Chemical Vapor Deposition) apparatus was used to realize the method for manufacturing an epitaxial wafer. 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 the N source, trimethyl gallium (TMGa) and triethyl gallium (TEGa) as gallium sources, trimethyl indium (TMIn) as indium sources, Silane (SiH)4) As N-type dopant, trimethylaluminum (TMAl) as aluminum source, magnesium diclomentate (CP)2Mg) as a P-type dopant. The pressure in the reaction chamber is 100 to 600 torr.
Step 402, growing a low temperature buffer layer on a substrate.
Wherein, the low-temperature buffer layer is a GaN layer.
Illustratively, the temperature in the reaction cavity is controlled to be 530-560 ℃, the pressure is controlled to be 200-500 torr, and a low-temperature buffer layer with the thickness of 15-30 nm is grown on the [0001] surface of the sapphire.
Step 403, growing a high temperature buffer layer on the low temperature buffer layer.
Wherein, the high-temperature buffer layer is a GaN layer.
Illustratively, the temperature in the reaction chamber is controlled to be 1000-1100 ℃, the pressure is controlled to be 200-600 torr, and a high-temperature buffer layer with the thickness of 2-3.5um is grown on the transition layer.
Step 404, an N-type layer is grown on the high temperature buffer layer.
Wherein the N-type layer is a GaN layer doped with Si.
Illustratively, the temperature in the reaction chamber is controlled to be 1000-1100 ℃, the pressure is controlled to be 150-300 torr, and an N-type layer with the thickness of 2-3 um is grown on the transition layer.
Step 405, grow an active layer on the N-type layer.
The multiple quantum well layer comprises a plurality of InGaN well layers and GaN barrier layers which alternately grow in a periodic mode. The number of cycles of the MQW layer can be 5-11. The thickness of the InGaN well layer is 2 nm-4 nm, preferably 3.5nm, and the thickness of the GaN barrier layer is 9 nm-20 nm, preferably 12 nm.
Illustratively, step 405 may include:
controlling the temperature in the reaction chamber to be 760-780 ℃ and the pressure to be 200torr, and growing a quantum well layer;
and controlling the temperature in the reaction cavity to be 860-890 ℃ and the pressure to be 200torr, and growing the quantum barrier layer.
And 406, growing a plurality of periods of alternately grown electron blocking layers and P-type layers on the active layer.
And along the stacking direction of the epitaxial wafer, the Al component in the electron blocking layers in each period is gradually reduced, the thickness is gradually reduced, and the doping concentration of Mg in the P-type layers in each period is gradually increased.
Optionally, m periods of alternately grown electron blocking layers and P-type layers are grown on the active layer, wherein m is more than or equal to 2 and less than or equal to 6.
If the number of m is too large, the growth process is complicated, and the growth period is slow. If the number of m is too small, the effect of blocking electrons many times cannot be achieved, and thus the effect of preventing the overflow of electrons cannot be effectively achieved.
Optionally, the variation range of the Al component in the electron blocking layers is 0.1-0.4.
If the content of the Al component in the electron blocking layer is too high, holes may be blocked, and injection of holes may be adversely affected. If the content of the Al component in the electron blocking layer is too low, the electron blocking layer cannot have a good blocking effect on electrons, and the electrons are prevented from overflowing.
Illustratively, the Al composition in the plurality of electron blocking layers gradually decreases from 0.4 to 0.1.
Optionally, the reduction range of the Al component in the electron blocking layers is 0.05-0.25.
If the reduction range of the Al component in the electron blocking layers is too large, the number of layers of the grown electron blocking layers is small, and therefore electrons cannot be blocked for many times, and a good effect of preventing electron overflow cannot be achieved. If the reduction range of the Al component in the electron blocking layers is too small, the number of layers of the electron blocking layers to be grown is large and the growth period is long on the premise of ensuring the effect of preventing electron overflow.
Optionally, the thickness of the electron blocking layers varies from 1nm to 20 nm.
If the thickness of the electron blocking layer is too thick, holes are blocked, and the injection of holes is adversely affected. If the thickness of the electron blocking layer is too thin, the electron blocking layer cannot have a good blocking effect on electrons, and the electrons are prevented from overflowing.
Illustratively, the thickness of the plurality of electron blocking layers is gradually reduced from 20nm to 1 nm.
Optionally, the thickness of the electron blocking layers is reduced by 5-15 nm.
If the reduction range of the thicknesses of the electron blocking layers is too large, the number of layers of the grown electron blocking layers is small, so that electrons cannot be blocked for multiple times, and a good effect of preventing electron overflow cannot be achieved. If the thickness of the electron blocking layers is too small, the number of layers of the electron blocking layers to be grown is large on the premise of ensuring the effect of preventing electron overflow, and the growth period is long.
Optionally, the P-type layer is a Mg-doped GaN layer.
Optionally, the doping concentration of Mg in the plurality of P-type layers varies in a range of 5 x 1017cm-3~6*1020cm-3。
If the doping concentration of Mg in the P-type layer is too high, non-radiative recombination between some holes and leaked electrons is easily caused, thereby reducing the light emitting efficiency. If the doping concentration of Mg in the P-type layer is too low, the effect of effectively improving hole injection cannot be achieved.
Illustratively, the doping concentration of Mg in the P-type layers is 5 × 1017cm-3Gradually increase to 6 x 1020cm-3。
Optionally, the doping concentration of Mg in the P-type layers is increased by 5 × 1017cm-3~6.5*1020cm-3。
If the doping concentration of Mg in the P-type layers is increased too much, the number of layers of the grown P-type layers is reduced, and the effect of maximizing the number and concentration of holes cannot be obtained. If the increase of the Mg doping concentration of the P-type layers is too small, the number of layers of the P-type layers to be grown is large on the premise of ensuring the number of the provided holes, and the growth period is long.
Optionally, the thicknesses of the P-type layers are gradually reduced, and the variation range of the thicknesses of the P-type layers 7 is 2-25 nm.
If the thickness of the P-type layer in each period is too thick, the P-type layer absorbs light, thereby reducing the light emitting efficiency of the light emitting diode, and if the thickness of the P-type layer in each period is too thin, sufficient holes and electrons cannot be provided for radiative recombination light emission, thereby also reducing the light emitting efficiency of the light emitting diode.
Illustratively, the thickness of the plurality of P-type layers is gradually reduced from 25nm to 2 nm.
Optionally, the reduction range of the thickness of the plurality of P-type layers is 2-15 nm.
If the reduction in the thickness of the P-type layers is too great, the number of layers of the grown P-type layers is small, and the effect of maximizing the number and concentration of holes cannot be obtained. If the reduction range of the thicknesses of the P-type layers is too small, the number of layers of the P-type layers to be grown is large on the premise of ensuring the internal quantum efficiency, and the growth period is long.
Optionally, the growth temperature of each of the electron blocking layers is 930-970 ℃, and the growth pressure is 100-200 torr.
If the growth temperature of the electron blocking layer is too high, In components In the quantum wells are separated out, and the crystal quality is affected. If the growth temperature of the electron blocking layer is too low, the growth quality of the electron blocking layer is deteriorated.
If the growth pressure of the electron blocking layer is too high, more pre-reaction is caused. If the growth pressure of the electron blocking layer is too low, the growth rate is too low, and the Al doping effect is influenced.
Optionally, the growth temperature of the P-type layers is 940-980 ℃, and the growth pressure is 200-600 torr.
If the growth temperature of the P-type layer is too high, In precipitation of the quantum well layer close to the P-type layer is increased, and the growth quality of the interface is affected. If the growth temperature of the P-type layer is too low, the doping of Mg in the P-type layer is not facilitated.
If the growth pressure of the P-type layer is too high, the surface becomes rough, and the flatness of the whole epitaxial wafer is affected. If the growth pressure of the P-type layer is too low, the doping of Mg in the P-type layer is not facilitated.
The embodiment of the disclosure arranges a plurality of electron blocking layers and P-type layers which are alternately grown in a periodic manner, wherein the Al component in the electron blocking layers in each period is gradually reduced and the thickness is gradually reduced along the lamination direction of the epitaxial wafer. That is, in the direction from the active layer to the P-type layer, the Al composition in the electron blocking layer near the active layer is the highest and the thickness is the thickest, so that most of electrons leaking from the active layer can be blocked, and the electrons can be prevented from overflowing. And the electron blocking layers of a plurality of subsequent periods need less blocked electrons, so that the Al component and the thickness can be gradually reduced and gradually reduced, and the leaked small part of electrons can be further blocked, so that the effect of better preventing the overflow of the electrons is achieved. Meanwhile, the blocking of holes provided by the P-type layer can be reduced, and the injection of the holes is favorably improved. Further, the doping concentration of Mg in the P-type layer of each period gradually increases, that is, the doping concentration of Mg in the P-type layer close to the active layer is the highest in the direction from the active layer to the P-type layer, so that more holes are provided, and the P-type layer and the electrons are radiated and recombined in the active layer to emit light. And the arrangement of a plurality of P-type layers can provide the maximized number and concentration of holes so as to form larger hole potential energy flow, thereby greatly increasing the injection of the holes. Therefore, the adoption of the epitaxial structure can effectively increase the overlapping degree of wave functions of electrons and holes on spatial distribution, and further improve the internal quantum efficiency of the diode.
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 (8)

1. A light emitting diode epitaxial wafer comprises a substrate, and a low-temperature buffer layer, a high-temperature buffer layer, an N-type layer and an active layer which are sequentially laminated on the substrate,
the light-emitting diode epitaxial wafer further comprises a plurality of electronic barrier layers and P-type layers which are sequentially stacked on the active layer and alternately grow periodically, each electronic barrier layer is an AlGaN layer, Al components in the electronic barrier layers in each period are gradually reduced along the stacking direction of the epitaxial wafer, the thickness of the electronic barrier layers is gradually reduced, and the doping concentration of Mg in the P-type layers in each period is gradually increased;
the plurality of periodically and alternately grown electron blocking layers and P-type layers include:
the first electron blocking layer, the first P type layer, the second electron blocking layer, the second P type layer, the third electron blocking layer and the third P type layer are sequentially stacked on the active layer;
the first P type layer, the second P type layer and the third P type layer are all GaN layers doped with Mg, and the doping concentration of Mg in the first P type layer is 5 x 1017cm-3~2*1018cm-3The thickness of the first P type layer is 15-25 nm, and the doping concentration of Mg in the second P type layer is 5 x 1018cm-3~5*1019cm-3The thickness of the second P type layer is 10-20 nm, and the doping concentration of Mg in the third P type layer is 1 x 1020cm-3~6*1020cm-3And the thickness of the third P type layer is 2-8 nm.
2. The light-emitting diode epitaxial wafer as claimed in claim 1, wherein the Al composition in the electron blocking layers varies in a range of 0.1 to 0.4.
3. The light-emitting diode epitaxial wafer according to claim 2, wherein the reduction range of the Al component in the plurality of electron blocking layers is 0.05-0.25.
4. The light-emitting diode epitaxial wafer according to claim 1, wherein the thickness of the electron blocking layers varies from 1nm to 20 nm.
5. The light-emitting diode epitaxial wafer according to claim 4, wherein the thickness of the electron blocking layers is reduced by 5-15 nm.
6. A manufacturing method of a light emitting diode epitaxial wafer is characterized by comprising the following steps:
providing a substrate;
sequentially growing a low-temperature buffer layer, a high-temperature buffer layer, an N-type layer and an active layer on the substrate;
growing a plurality of electron blocking layers and P-type layers which alternately grow in cycles on the active layer, wherein each electron blocking layer is an AlGaN layer, along the lamination direction of the epitaxial wafer, the Al component in the electron blocking layers in each cycle is gradually reduced, the thickness is gradually reduced, and the doping concentration of Mg in the P-type layers in each cycle is gradually increased;
the plurality of periodically and alternately grown electron blocking layers and P-type layers include:
the first electron blocking layer, the first P type layer, the second electron blocking layer, the second P type layer, the third electron blocking layer and the third P type layer are sequentially stacked on the active layer;
the first P type layer, the second P type layer and the third P type layer are all Mg-doped GaN layers, and the doping concentration of Mg in the first P type layer is 5 x 1017cm-3~2*1018cm-3The thickness of the first P type layer is 15-25 nm, and the doping concentration of Mg in the second P type layer is 5 x 1018cm-3~5*1019cm-3The thickness of the second P type layer is 10-20 nm, and the doping of Mg in the third P type layerConcentration of 1 x 1020cm-3~6*1020cm-3And the thickness of the third P type layer is 2-8 nm.
7. The method according to claim 6, wherein the electron blocking layers are grown at 930 to 970 ℃ and at 100 to 200 torr.
8. The method according to claim 6, wherein the growth temperature of the P-type layers is 940-980 ℃ and the growth pressure is 200-600 torr.
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