CN114784150A - Epitaxial wafer of deep ultraviolet light-emitting diode and preparation method thereof - Google Patents

Epitaxial wafer of deep ultraviolet light-emitting diode and preparation method thereof Download PDF

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CN114784150A
CN114784150A CN202210167768.2A CN202210167768A CN114784150A CN 114784150 A CN114784150 A CN 114784150A CN 202210167768 A CN202210167768 A CN 202210167768A CN 114784150 A CN114784150 A CN 114784150A
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layer
algan
aln
substrate
thickness
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尹涌
易丁丁
张琰琰
陆香花
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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
    • H01L33/005—Processes
    • H01L33/0062—Processes for devices with an active region comprising only III-V compounds
    • H01L33/0075—Processes for devices with an active region comprising only III-V compounds 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
    • H01L33/005—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
    • 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
    • H01L33/0095—Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
    • 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
    • H01L33/04—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 quantum effect structure or superlattice, e.g. tunnel junction
    • H01L33/06—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 quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier
    • 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 an epitaxial wafer of a deep ultraviolet light-emitting diode and a preparation method thereof, belonging to the technical field of photoelectron manufacturing. The preparation method of the epitaxial wafer comprises the following steps: providing a substrate; forming an AlN film layer on the substrate; forming an AlGaN composite layer on the AlN film layer, wherein the AlGaN composite layer comprises a plurality of first AlGaN layers and a plurality of second AlGaN layers which are sequentially and alternately laminated, the first AlGaN layers grow in a mixed atmosphere of nitrogen and hydrogen, and the second AlGaN layers grow in a hydrogen atmosphere; and forming a light emitting structure on the AlGaN composite layer. The AlGaN layer with a flat surface and low dislocation density can be grown, the crystal quality of a subsequently grown film layer is improved, and the starting voltage yield of the deep ultraviolet light-emitting diode is improved.

Description

Epitaxial wafer of deep ultraviolet light-emitting diode and preparation method thereof
Technical Field
The disclosure relates to the technical field of photoelectron manufacturing, in particular to an epitaxial wafer of a deep ultraviolet light emitting diode and a preparation method thereof.
Background
The Light Emitting Diode (LED) is a new product with great influence in the photoelectronic industry, has the characteristics of small volume, long service life, rich and colorful colors, low energy consumption and the like, and is widely applied to the fields of illumination, display screens, signal lamps, backlight sources, toys and the like. The core structure of the LED is an epitaxial wafer, and the manufacturing of the epitaxial wafer has great influence on the photoelectric characteristics of the LED.
In the related art, an epitaxial wafer generally includes an AlN layer, an AlGaN layer, an n-type layer, a multiple quantum well layer, and a p-type layer, which are sequentially stacked on a substrate. During epitaxial growth, a high temperature annealing process is typically employed to improve the crystal quality of the AlN layer.
However, when the AlGaN layer is epitaxially grown on the AlN template annealed at high temperature, many hillocks are formed on the surface of the AlGaN layer, which easily affects the crystal quality of a subsequently grown film layer, and reduces the yield of the turn-on voltage of the deep ultraviolet light emitting diode.
Disclosure of Invention
The embodiment of the disclosure provides an epitaxial wafer of a deep ultraviolet light-emitting diode and a preparation method thereof, which can grow an AlGaN layer with a smooth surface and low dislocation density, improve the crystal quality of a subsequently grown film layer, and improve the turn-on voltage yield of the deep ultraviolet light-emitting diode. The technical scheme is as follows:
in one aspect, an embodiment of the present disclosure provides an epitaxial wafer of a deep ultraviolet light emitting diode, where the epitaxial wafer includes a substrate, and an AlN film layer, an AlGaN composite layer, and a light emitting structure that are sequentially formed on the substrate; the AlGaN composite layer comprises a plurality of first AlGaN layers and a plurality of second AlGaN layers which are alternately stacked in sequence, wherein the first AlGaN layers grow in the mixed atmosphere of nitrogen and hydrogen, and the second AlGaN layers grow in the atmosphere of hydrogen.
Optionally, the first AlGaN layer has a thickness not greater than a thickness of the second AlGaN layer.
Optionally, the thickness of the first AlGaN layer is 1nm to 10nm, and the thickness of the second AlGaN layer is 1nm to 10 nm.
Optionally, the number of cycles in which the first AlGaN layer and the second AlGaN layer are alternately stacked is 5 to 50.
Optionally, the AlN film layer includes a first AlN layer and a second AlN layer sequentially stacked on the substrate, the first AlN layer having a thickness of 10nm to 500nm, and the second AlN layer having a thickness of 500nm to 2000 nm.
On the other hand, the embodiment of the present disclosure further provides a preparation method of an epitaxial wafer of a deep ultraviolet light emitting diode, where the preparation method includes:
providing a substrate;
forming an AlN film layer on the substrate;
forming an AlGaN composite layer on the AlN film layer, wherein the AlGaN composite layer comprises a plurality of first AlGaN layers and a plurality of second AlGaN layers which are sequentially and alternately laminated, the first AlGaN layers grow in a mixed atmosphere of nitrogen and hydrogen, and the second AlGaN layers grow in a hydrogen atmosphere;
and forming a light emitting structure on the AlGaN composite layer.
Optionally, the AlGaN composite layer is formed in a manner that a volume ratio of nitrogen to hydrogen is 1: and growing in a mixed atmosphere of 5 to 1: 20.
Optionally, the growth temperature of the first AlGaN layer is 1000 ℃ to 1200 ℃, and the growth pressure is 30mbar to 70 mbar; the growth temperature of the second AlGaN layer is 1000-1200 ℃, and the growth pressure is 30-70 mbar.
Optionally, when the first AlGaN layer is grown, ammonia gas, trimethylaluminum and trimethylgallium are introduced as reactants, wherein the introduction amount of nitrogen is 4000sccm to 6000sccm, and the introduction amount of hydrogen is 40000sccm to 60000 sccm; and introducing ammonia gas, trimethylaluminum and trimethylgallium as reactants when the second AlGaN layer grows, wherein the introduction amount of the hydrogen gas is 50000sccm to 60000 sccm.
Optionally, the forming an AlN film layer on the substrate includes: depositing a first AlN layer on the surface of the substrate by adopting a physical vapor deposition method; annealing the first AlN layer in a nitrogen atmosphere at a temperature of 1500-2000 ℃; growing a second AlN layer on the first AlN layer by metal organic chemical vapor deposition.
The beneficial effect that technical scheme that this disclosure embodiment provided brought includes at least:
the epitaxial wafer of the deep ultraviolet light-emitting diode provided by the implementation of the disclosure comprises an AlN film layer, an AlGaN composite layer and a light-emitting structure which are formed on a substrate. The AlGaN composite layer comprises a plurality of first AlGaN layers and a plurality of second AlGaN layers which are sequentially and alternately stacked. Since the AlGaN composite layer is grown on the smooth AlN film layer as a transition layer in this way, since the first AlGaN layer is grown in a mixed atmosphere of nitrogen and hydrogen, the density of the screw dislocation and the mixed dislocation of the grown AlGaN film can be increased to interrupt the formation of hillocks, thereby reducing the size of the hillocks. And the second AlGaN layer grows in a pure hydrogen atmosphere, so that the AlGaN film with better crystal quality can be obtained. Like this with first AlGaN layer and the alternate growth of second AlGaN layer, the formation of hillock can be reduced on first AlGaN layer, rete crystal quality can be guaranteed on the second AlGaN layer, consequently this AlGaN composite bed when reducing the size of hillock, also can guarantee the crystal quality of AlGaN film, effectual reduction because the dislocation that heterojunction substrate and epitaxial layer produced because of the lattice mismatch to improve the crystal quality of the rete of the follow-up growth of epitaxial growth, promote deep ultraviolet emitting diode's opening voltage yield.
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 epitaxial wafer of a deep ultraviolet light emitting diode provided in an embodiment of the present disclosure;
fig. 2 is a flowchart of a method for manufacturing an epitaxial wafer of a deep ultraviolet light emitting diode according to an embodiment of the present disclosure;
fig. 3 is a schematic view of a process for preparing an epitaxial wafer of a deep ultraviolet light emitting diode according to an embodiment of the present disclosure;
fig. 4 is a schematic view of a process for preparing an epitaxial wafer of a deep ultraviolet light emitting diode according to an embodiment of the present disclosure.
The individual labels in the figures are illustrated as follows:
10. a substrate;
20. an AlN film layer; 21. a first AlN layer; 22. a second AlN layer;
30. an AlGaN composite layer; 31. a first AlGaN layer; 32. a second AlGaN layer;
40. a light emitting structure; 41. an n-type AlGaN layer; 42. a multi-quantum well layer, 43, p-type layer;
421、AlxGa1-xan N quantum well layer; 422. al (Al)yGa1-yAn N quantum barrier layer;
431. a p-type barrier layer; 432. a p-type AlGaN layer; 433. and a p-type GaN layer.
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 epitaxial wafer of a deep ultraviolet light emitting diode provided in an embodiment of the present disclosure. As shown in fig. 1, the epitaxial wafer includes a substrate 10, and an AlN film layer 20, an AlGaN composite layer 30, and a light emitting structure 40 sequentially formed on the substrate 10.
As shown in fig. 1, the AlGaN composite layer 30 includes a plurality of first AlGaN layers 31 and a plurality of second AlGaN layers 32 alternately stacked in this order, the first AlGaN layers 31 being grown in a mixed atmosphere of nitrogen and hydrogen, and the second AlGaN layers 32 being grown in a pure hydrogen atmosphere.
The epitaxial wafer of the deep ultraviolet light emitting diode provided by the embodiment of the present disclosure includes an AlN film layer 20, an AlGaN composite layer 30, and a light emitting structure 40 formed on a substrate 10. The AlGaN composite layer 30 includes a plurality of first AlGaN layers 31 and a plurality of second AlGaN layers 32 alternately stacked in this order. Thus, the AlGaN composite layer 30 is grown as a transition layer on the smooth AlN film layer 20, and since the first AlGaN layer 31 is grown in a mixed atmosphere of nitrogen and hydrogen, the density of the screw dislocation and the mixed dislocation of the grown AlGaN film can be increased to interrupt the formation of the hillock, thereby reducing the size of the hillock. And the second AlGaN layer 32 grows in a pure hydrogen atmosphere, so that an AlGaN film with better crystal quality can be obtained. Like this with first AlGaN layer 31 and the alternative growth of second AlGaN layer 32, the formation of hillock can be reduced on first AlGaN layer 31, rete crystal quality can be guaranteed on second AlGaN layer 32, consequently this AlGaN composite bed 30 when reducing the size of hillock, also can guarantee the crystal quality of AlGaN film, the effectual dislocation that has reduced because heterojunction substrate 10 and epitaxial layer produce because of the lattice mismatch, thereby improve the crystal quality of the rete of the follow-up growth of epitaxial growth, promote deep ultraviolet emitting diode's opening voltage yield.
Alternatively, the substrate 10 is a sapphire substrate, a silicon substrate, zinc oxide, quartz glass, or a silicon carbide substrate. The substrate 10 may be a flat substrate or a patterned substrate.
As an example, in the embodiments of the present disclosure, the substrate 10 is a sapphire substrate. The sapphire substrate is a common substrate, the technology is mature, and the cost is low. The substrate can be a patterned sapphire substrate or a sapphire flat sheet substrate.
Alternatively, as shown in fig. 1, the light emitting structure 40 includes an n-type AlGaN layer 41, a multiple quantum well layer 42, and a p-type layer 43, which are sequentially stacked on the AlGaN composite layer 30.
In the embodiment of the present disclosure, the thickness of the n-type AlGaN layer is 1000nm to 2000 nm. As an example, the thickness of the n-type AlGaN layer is 1500 nm.
Optionally, the doping concentration of silicon in the n-type AlGaN layer is 1017cm-3To 1019cm-3. Too high a doping concentration of silicon may decrease crystal quality, resulting in an increase in defects, and too low a doping concentration of silicon may decrease conductivity of the n-type AlGaN layer. Controlling the doping concentration of silicon within this range enables the n-type AlGaN layer to have a good crystal quality while also having sufficient conductivity.
As an example, in the embodiments of the present disclosure, the doping concentration of silicon in the n-type AlGaN layer is 5 × 1018cm-3。
Optionally, the MQW layer 42 comprises 3 to 8 AlxGa1-xN quantum well layer 421 and AlyGa1-yAnd the N quantum barrier layers 422, wherein x is more than 0 and less than y is less than 1. That is, the multiple quantum well layer 42 includes Al of 3 to 8 periods alternately stackedxGa1-xN quantum well layer 421 and AlyGa1-yN quantum barrier layer422。
As an example, in the embodiment of the present disclosure, the multiple quantum well layer 42 includes 5 periods of Al alternately stackedxGa1-xN quantum well layer 421 and AlyGa1-yN quantum barrier layer 422.
Alternatively, AlxGa1-xThe thickness of the N quantum well layer 421 may be 2nm to 4 nm. Al (Al)yGa1-yThe thickness of the N quantum barrier layer 422 may be 9nm to 14 nm.
Exemplarily, in the embodiments of the present disclosure, AlxGa1-xThe thickness of the N quantum well layer 421 is 3 nm. Al (aluminum)yGa1-yThe thickness of the N quantum barrier layer 422 is 11 nm.
It should be noted that fig. 1 only shows a partial structure of the mqw layer 42, and is not intended to limit AlxGa1-xN quantum well layer 421 and AlyGa1-yThe number of cycles of alternately stacking the N quantum barrier layers 422, and Al may be grown on the N-type AlGaN layer when the multiple quantum well layer 42 is grownyGa1-yAnd an N quantum barrier layer 422.
In the present embodiment, the p-type layer 43 includes a p-type barrier layer 431, a p-type AlGaN layer 432, and a p-type GaN layer 433, which are sequentially stacked on the multiple quantum well layer 42. The p-type barrier layer 431, the p-type AlGaN layer 432, and the p-type GaN layer 433 are all Mg-doped.
Illustratively, the p-type barrier layer 431 is an AlGaN layer.
Wherein the thickness of the p-type barrier layer 431 is 5nm to 15 nm. As an example, in the embodiments of the present disclosure, the thickness of the p-type barrier layer 431 is 10 nm. If the thickness of the p-type blocking layer 431 is too thin, the blocking effect on electrons is reduced, and if the thickness of the p-type blocking layer 431 is too thick, the absorption of light by the p-type blocking layer 431 is increased, thereby reducing the light emitting efficiency of the deep ultraviolet light emitting diode.
Illustratively, the p-type AlGaN layer 432 has a thickness of 20nm to 30 nm. As an example, in the disclosed embodiment, the thickness of the p-type AlGaN layer 432 is 25 nm.
Illustratively, the thickness of the p-type GaN layer 433 is 30nm to 70 nm. As an example, in the embodiments of the present disclosure, the thickness of the p-type GaN layer 433 is 50 nm.
In the embodiment of the present disclosure, the AlN film layer 20 grown on the substrate 10 serves as a buffer layer to facilitate carrier transport.
In the embodiment of the present disclosure, the AlN film layer 20 includes a first AlN layer 21 and a second AlN layer 22 sequentially stacked on the substrate 10, and the first AlN layer 21 is a film layer subjected to high-temperature annealing.
The first AlN layer 21 is annealed at a high temperature, which can improve the crystal quality of the first AlN layer 21. On the other hand, the AlGaN film layer is directly grown on the AlN film layer 20 after high-temperature annealing, which is easy to form hillocks on the surface of the AlGaN film, so that the growth of the second AlN layer 22 on the first AlN layer 21 can improve the problem that hillocks are easy to form on the surface of the AlGaN film, and is beneficial to the epitaxial growth of the AlGaN film.
Illustratively, the thickness of the first AlN layer 21 is 10nm to 500 nm. As an example, the thickness of the first AlN layer 21 is 200 nm.
Illustratively, the thickness of the second AlN layer 22 is 500nm to 2000 nm. As an example, the thickness of the second AlN layer 22 is 1000 nm.
The AlN film layer 20 is too thin to play a role in buffering the AlN film layer 20; if the AlN film 20 is too thick, the light absorption of the AlN film 20 may increase.
As an example, in the embodiment of the present disclosure, the thickness of the AlN film layer 20 is the sum of the thickness of the first AlN layer 21 and the thickness of the second AlN layer 22, and the thickness of the AlN film layer 20 may be 1200 nm.
In the embodiment of the present disclosure, the AlGaN composite layer 30 includes a plurality of first AlGaN layers 31 and a plurality of second AlGaN layers 32 that are alternately stacked. Here, the first AlGaN layer 31 is grown in a mixed atmosphere of nitrogen and hydrogen.
Alternatively, in the growth atmosphere of the first AlGaN layer 31, the volume ratio of nitrogen gas to hydrogen gas is 1: 5 to 1: 20. By setting the volume ratio of nitrogen to hydrogen to this ratio, a good mixed atmosphere environment is formed, the density of screw dislocation and mixed dislocation of the first AlGaN layer 31 that grows can be increased to interrupt the formation of a hillock, thereby reducing the size of the hillock, and effectively reducing dislocation generated due to lattice mismatch between the heterojunction substrate 10 and the epitaxial layer, thereby improving the crystal quality of the film that is grown subsequently.
As an example, in growing the first AlN layer 21, the flow rate of nitrogen may be 5000 seem, and the flow rate of hydrogen may be 50000 seem, i.e., the volume ratio of nitrogen to hydrogen is 1: 10. Such a volume ratio forms a good mixed atmosphere, and the density of screw dislocations and mixed dislocations of the grown first AlGaN layer 31 can be increased to interrupt the formation of hillocks, thereby reducing the size of the hillocks.
Optionally, the thickness of the first AlGaN layer 31 is not larger than the thickness of the second AlGaN layer 32. The thickness of the first AlGaN layer 31 is set to be smaller than or equal to that of the second AlGaN layer 32, so that the first AlGaN layer 31 is prevented from being too large in thickness, the thickness of the first AlGaN layer 31 with larger screw dislocation and larger dislocation density is reduced on the premise of ensuring that the size of a hillock is reduced, and the crystal quality of the AlGaN film is improved.
Alternatively, the first AlGaN layer 31 has a thickness of 1nm to 10nm, and the second AlGaN layer 32 has a thickness of 1nm to 10 nm.
As an example, in the presently disclosed embodiment, the thickness of the first AlGaN layer 31 is 5nm, and the thickness of the second AlGaN layer 32 is 5 nm.
Alternatively, the number of the first AlGaN layers 31 is 5 to 50, and the number of the second AlGaN layers 32 is 5 to 50.
Illustratively, as shown in fig. 1, the AlGaN composite layer 30 includes 5 first AlGaN layers 31 and 5 second AlGaN layers 32 alternately stacked in this order.
The first AlGaN layer 31 and the second AlGaN layer 32 are provided in this number, so that the grown AlGaN thin film can be ensured to have a certain dislocation density, and the formation of hillocks is interrupted, thereby reducing the size of the hillocks. And a sufficient amount of crystal and a higher quality second AlGaN layer 32 can be obtained. Therefore, the AlGaN composite layer 30 can reduce the size of the hillock, and simultaneously can ensure the crystal quality of the AlGaN thin film, thereby effectively reducing the dislocation generated by lattice mismatch between the heterojunction substrate 10 and the epitaxial layer, improving the crystal quality of the film layer grown subsequently by epitaxial growth, and improving the yield of the turn-on voltage of the deep ultraviolet light emitting diode.
Fig. 2 is a flowchart of a method for manufacturing an epitaxial wafer of a deep ultraviolet light emitting diode according to an embodiment of the present disclosure. The method is used for preparing the epitaxial wafer shown in fig. 1. As shown in fig. 2, the preparation method comprises:
s11: a substrate 10 is provided.
Alternatively, the substrate 10 is a sapphire substrate, a silicon substrate, or a silicon carbide substrate. The substrate can be a flat substrate or a patterned substrate.
As an example, in the embodiments of the present disclosure, the substrate 10 is a sapphire substrate. The sapphire substrate is a common substrate, the technology is mature, and the cost is low. The method can be embodied as a patterned sapphire substrate or a sapphire flat sheet substrate.
In step S11, the sapphire substrate may be pretreated, placed in an MOCVD (Metal-organic Chemical Vapor Deposition) reaction chamber, and subjected to a baking process for 12 to 18 minutes. As an example, in the embodiment of the present disclosure, the sapphire substrate was subjected to a baking treatment for 15 minutes.
Specifically, the baking temperature can be 1000 ℃ to 1200 ℃, and the pressure in the MOCVD reaction chamber during baking can be 100mbar to 200 mbar.
Step S12: an AlN film layer 20 is formed on the substrate 10.
As shown in fig. 3, the AlN film layer 20 grown on the substrate 10 includes a first AlN layer 21 and a second AlN layer 22 sequentially stacked on the substrate 10.
In growing the AlN film layer 20, the following steps may be included:
in a first step, a first AlN layer 21 is deposited on the surface of the substrate 10 using a physical vapor deposition method.
Second, the first AlN layer 21 is annealed in a nitrogen atmosphere at a temperature of 1500 ℃ to 2000 ℃.
Third, a second AlN layer 22 is grown on the first AlN layer 21 using metal-organic chemical vapor deposition.
The first step may include: the substrate 10 is placed in a Physical Vapor Deposition (PVD) apparatus, and a first AlN layer 21 is grown. The process temperature of PVD is 600 ℃, the mixed gas of nitrogen and argon is introduced, and the deposition thickness is 200 nm.
The second step may include: the first AlN layer 21 on which the substrate 10 is deposited is placed in a high-temperature annealing furnace and annealed at 1700 ℃ for 260min under a pure nitrogen atmosphere. The first AlN layer 21 is annealed at a high temperature, which can improve the crystal quality of the first AlN layer 21.
The third step may include: the substrate 10 with the first AlN layer 21 grown thereon is placed in MOCVD, the temperature is raised to 1000 ℃ to 1500 ℃ to grow a second AlN layer 22 with a thickness of 1000nm, the growth pressure is 50mbar, ammonia gas and trimethylaluminum are introduced as reactants, the V/III molar ratio is 300, and the process time is 5000 s.
Wherein the growth temperature of the second AlN layer 22 may be 1350 ℃. The growth temperature affects the growth of the AlN thin film, and a second AlN layer 22 of good quality can be grown in this temperature range.
Step S13: an AlGaN composite layer 30 is formed on the AlN film layer 20.
As shown in fig. 4, growing the AlGaN composite layer 30 may include the following two steps:
in the first step, the volume ratio of nitrogen to hydrogen is 1: the first AlGaN layer 31 is grown in a mixed atmosphere of 5 to 1: 20.
Second, a second AlGaN layer 32 is grown in a pure hydrogen atmosphere.
In the first step, when the first AlGaN layer 31 is grown, the temperature is 1000 ℃ to 1200 ℃, the growth pressure is 30mbar to 70mbar, ammonia gas, trimethylaluminum and trimethylgallium are introduced as reactants, the introduction amount of nitrogen gas is 4000sccm to 6000sccm, and the introduction amount of hydrogen gas is 40000sccm to 60000 sccm.
In the second step, when the second AlGaN layer 32 is grown, the temperature is 1000 ℃ to 1200 ℃, the growth pressure is 30mbar to 70mbar, ammonia gas, trimethylaluminum and trimethylgallium are introduced as reactants, and the introduction amount of hydrogen gas is 50000sccm to 60000 sccm.
Illustratively, the first AlGaN layer 31 is grown at 1150 ℃ under a growth pressure of 50mbar while ammonia, trimethylaluminum and trimethylgallium are fed as reactants. And the flow rate of nitrogen was set to 5000sccm, the flow rate of hydrogen was set to 50000sccm, and the first AlGaN layer 31 having a thickness of 5nm was grown.
Illustratively, the second AlGaN layer 32 is grown at 1150 ℃ under a growth pressure of 50mbar, and ammonia, trimethylaluminum, and trimethylgallium are introduced as reactants. The amount of hydrogen gas introduced was set to 55000sccm, and the second AlGaN layer 32 was grown to a thickness of 5 nm.
In the embodiment of the present disclosure, the formed AlGaN composite layer 30 is cycled through the first step and the second step five times, so as to obtain the AlGaN composite layer 30 having 5 first AlGaN layers 31 and 5 second AlGaN layers 32.
Alternatively, the first AlGaN layer 31 has a thickness of 1nm to 10nm, and the second AlGaN layer 32 has a thickness of 1nm to 10 nm.
As an example, in the embodiment of the present disclosure, the thickness of the first AlGaN layer 31 is 5nm, and the thickness of the second AlGaN layer 32 is 5 nm.
Step S14: a light emitting structure 40 is formed on the AlGaN composite layer 30.
As shown in fig. 1, the light emitting structure 40 includes an n-type AlGaN layer 41, a multiple quantum well layer 42, and a p-type layer 43, which are sequentially stacked on the AlGaN composite layer 30.
Wherein, when growing the n-type AlGaN layer, the process temperature is 1000-1200 ℃, the introducing amount of trimethyl aluminum is 30-70 sccm, the introducing amount of ammonia gas is 3000-5000 sccm, the introducing amount of trimethyl gallium is 100-200 sccm, and the introducing amount of silane is 5-20 sccm. To grow an n-type AlGaN layer with a thickness of 1500nm and a silicon doping concentration of 5 × 1018cm-3。
Illustratively, the process temperature is 1100 ℃, the flow rate of trimethylaluminum is 50sccm, the flow rate of ammonia is 4000sccm, the flow rate of trimethylgallium is 150sccm, and the flow rate of silane is 10 sccm.
Growing the MQW layer 42, growing Al for 3-8 periods under the conditions of growth pressure of 100-200 mbar and temperature of 1000-1200 ℃ in a nitrogen atmospherexGa1-xN/AlyGa1-yN(x<y) quantum well as active layer, AlxGa1-xThe N quantum well layer 421 has a thickness of 1 to 5nm and is made of AlyGa1-yThe thickness of the N quantum barrier layer 422 is 5nm to 15 nm.
Illustratively, Al is grown for 5 cycles at 1040 deg.C under 150mbar of growth pressurexGa1-xN/AlyGa1-yN(x<y) quantum well as active layer, AlxGa1-xThe N quantum well layer 421 has a thickness of 3nm and is made of AlyGa1-yThe thickness of the N quantum barrier layer 422 is 11 nm.
In the present embodiment, the p-type layer 43 includes a p-type barrier layer 431, a p-type AlGaN layer 432, and a p-type GaN layer 433 that are sequentially stacked on the multiple quantum well layer 42. The p-type barrier layer 431, the p-type AlGaN layer 432, and the p-type GaN layer 433 are all Mg-doped.
When the p-type layer 43 is grown, a layer of Mg-doped p-type barrier layer 431 is grown under the conditions that the temperature is 500-1500 ℃ and the growth pressure is 100-200 mbar.
Illustratively, a Mg-doped p-type barrier layer 431 is grown at a temperature of 980 ℃ and a growth pressure of 150 mbar.
As an example, the p-type barrier layer 431 is an AlGaN layer.
Wherein the thickness of the p-type barrier layer 431 is 5nm to 15 nm. As an example, in the embodiments of the present disclosure, the thickness of the p-type barrier layer 431 is 10 nm. If the thickness of the p-type blocking layer 431 is too thin, the blocking effect on electrons is reduced, and if the thickness of the p-type blocking layer 431 is too thick, the absorption of light by the p-type blocking layer 431 is increased, thereby reducing the light emitting efficiency of the deep ultraviolet light emitting diode.
Then, a p-type AlGaN layer 432 doped with Mg is grown at a temperature of 500 ℃ to 1500 ℃ and a growth pressure of 100mbar to 300 mbar.
Illustratively, a layer 432 of Mg-doped p-type AlGaN is grown at a temperature of 900 ℃ and a growth pressure of 200 mbar.
As an example, the p-type AlGaN layer 432 has a thickness of 20nm to 30 nm. In the disclosed embodiment, the p-type AlGaN layer 432 has a thickness of 25 nm.
Then, a Mg-doped p-type GaN layer 433 is grown under the conditions of a temperature of 500 ℃ to 1500 ℃ and a growth pressure of 200mbar to 500 mbar.
Illustratively, a layer of Mg-doped p-type GaN 433 is grown at a temperature of 850 ℃ and a growth pressure of 300 mbar.
As an example, the thickness of the p-type GaN layer 433 is 30nm to 70 nm. In the disclosed embodiment, the thickness of the p-type GaN layer 433 is 50 nm.
And finally, annealing the epitaxial wafer. Alternatively, annealing may be performed for 30 minutes in a nitrogen atmosphere to end the growth of the epitaxial wafer. And then the heating system and the gas supply system are closed, and the temperature of the reaction cavity is reduced to room temperature.
In particular implementations, embodiments of the present disclosure may employ high purity H2Or/and N2As carrier gas, TEGa or TMGa is used as Ga source, TMIn is used as In source, SiH4As n-type dopant TMAl as aluminium source, Cp2Mg acts 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 preparation method of an epitaxial wafer of a deep ultraviolet light emitting diode is characterized by comprising the following steps:
providing a substrate;
forming an AlN film layer on the substrate;
forming an AlGaN composite layer on the AlN film layer, wherein the AlGaN composite layer comprises a plurality of first AlGaN layers and a plurality of second AlGaN layers which are sequentially and alternately stacked, the first AlGaN layers grow in a mixed atmosphere of nitrogen and hydrogen, and the second AlGaN layers grow in a hydrogen atmosphere;
and forming a light emitting structure on the AlGaN composite layer.
2. The method according to claim 1, wherein the AlGaN composite layer is formed such that the volume ratio of nitrogen gas to hydrogen gas is 1: and (5) growing in a mixed atmosphere of 1: 20.
3. The method according to claim 1, wherein the first AlGaN layer is grown at a growth temperature of 1000 ℃ to 1200 ℃ and a growth pressure of 30mbar to 70 mbar;
the growth temperature of the second AlGaN layer is 1000-1200 ℃, and the growth pressure is 30-70 mbar.
4. The method according to claim 3, wherein ammonia gas, trimethylaluminum and trimethylgallium are introduced as reactants during the growth of the first AlGaN layer, wherein nitrogen gas is introduced in an amount of 4000sccm to 6000sccm, and hydrogen gas is introduced in an amount of 40000sccm to 60000 sccm;
and introducing ammonia gas, trimethylaluminum and trimethylgallium as reactants when the second AlGaN layer grows, wherein the introduction amount of the hydrogen gas is 50000sccm to 60000 sccm.
5. A production method according to any one of claims 1 to 4, wherein said forming an AlN film layer on the substrate comprises:
depositing a first AlN layer on the surface of the substrate by adopting a physical vapor deposition method;
annealing the first AlN layer in a nitrogen atmosphere at a temperature of 1500-2000 ℃;
growing a second AlN layer on the first AlN layer by metal organic chemical vapor deposition.
6. An epitaxial wafer of a deep ultraviolet light emitting diode is characterized in that the epitaxial wafer comprises a substrate (10), and an AlN film layer (20), an AlGaN composite layer (30) and a light emitting structure (40) which are sequentially formed on the substrate (10);
the AlGaN composite layer (30) comprises a plurality of first AlGaN layers (31) and a plurality of second AlGaN layers (32) which are alternately laminated in sequence, wherein the first AlGaN layers (31) grow in a mixed atmosphere of nitrogen and hydrogen, and the second AlGaN layers (32) grow in a hydrogen atmosphere.
7. Epitaxial wafer according to claim 6, characterized in that the thickness of the first AlGaN layer (31) is not greater than the thickness of the second AlGaN layer (32).
8. Epitaxial wafer according to claim 7, characterized in that the first AlGaN layer (31) has a thickness of 1 to 10nm and the second AlGaN layer (32) has a thickness of 1 to 10 nm.
9. An epitaxial wafer according to claim 6, characterized in that the number of periods in which the first AlGaN layers (31) and the second AlGaN layers (32) are alternately stacked is 5 to 50.
10. An epitaxial wafer according to any of claims 6 to 9, characterized in that the AlN film layer (20) comprises a first AlN layer (21) and a second AlN layer (22) laminated in this order on the substrate (10), the first AlN layer (21) having a thickness of 10nm to 500nm, and the second AlN layer (22) having a thickness of 500nm to 2000 nm.
CN202210167768.2A 2022-02-23 2022-02-23 Epitaxial wafer of deep ultraviolet light-emitting diode and preparation method thereof Pending CN114784150A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117476825A (en) * 2023-12-25 2024-01-30 北京中博芯半导体科技有限公司 AlGaN epitaxial structure growth method and application

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117476825A (en) * 2023-12-25 2024-01-30 北京中博芯半导体科技有限公司 AlGaN epitaxial structure growth method and application
CN117476825B (en) * 2023-12-25 2024-04-12 北京中博芯半导体科技有限公司 AlGaN epitaxial structure growth method and application

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