CN117080327A - Light-emitting diode epitaxial wafer and preparation method thereof - Google Patents
Light-emitting diode epitaxial wafer and preparation method thereof Download PDFInfo
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- 229910002704 AlGaN Inorganic materials 0.000 claims abstract description 54
- 230000007704 transition Effects 0.000 claims abstract description 46
- 230000004888 barrier function Effects 0.000 claims abstract description 44
- 239000000758 substrate Substances 0.000 claims abstract description 28
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- 238000000034 method Methods 0.000 claims description 8
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- 238000004519 manufacturing process Methods 0.000 claims description 4
- 230000008569 process Effects 0.000 claims description 2
- 239000004065 semiconductor Substances 0.000 abstract description 2
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 30
- 235000012431 wafers Nutrition 0.000 description 28
- 238000002248 hydride vapour-phase epitaxy Methods 0.000 description 10
- 238000001451 molecular beam epitaxy Methods 0.000 description 10
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- 238000010586 diagram Methods 0.000 description 3
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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
- H01L33/02—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
- H01L33/04—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 with a quantum effect structure or superlattice, e.g. tunnel junction
- H01L33/06—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 with a quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier
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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
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- 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
- H01L33/0075—Processes for devices with an active region comprising only III-V compounds comprising nitride compounds
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- H—ELECTRICITY
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- 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
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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
- H01L33/02—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
- H01L33/26—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 system
- H01L33/32—Materials of the light emitting region containing only elements of group III and group V of the periodic system containing nitrogen
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- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The invention discloses a light-emitting diode epitaxial wafer and a preparation method thereof, and relates to the field of semiconductor photoelectric devices. The light-emitting diode epitaxial wafer sequentially comprises a substrate, a buffer layer, an N-type AlGaN layer, a multiple quantum well layer, an electron blocking layer and a P-type AlGaN layer; the multi-quantum well layer is of a periodic structure, and the period number is more than or equal to 3; the multi-quantum well layer of each period comprises a quantum barrier layer, a first transition layer, a quantum well layer and a second transition layer which are sequentially stacked; wherein the quantum barrier layer is Al y Ga 1‑y N layer, quantum well layer is Al x Ga 1‑x An N layer; x is 0.3-0.5, y is 0.4-0.6, and x is less than y; the first transition layer comprises a first InN layer and a first AlN layer which are sequentially laminated on the quantum barrier layer; second passThe transition layer comprises a second AlN layer and a second InN layer which are sequentially laminated on the quantum well layer. By implementing the invention, the luminous efficiency of the LED epitaxial wafer can be improved.
Description
Technical Field
The invention relates to the field of semiconductor photoelectric devices, in particular to a light-emitting diode epitaxial wafer and a preparation method thereof.
Background
Ultraviolet LEDs (UV LEDs) are mainly used in biomedical, anti-counterfeit, purification (water, air, etc.), computer data storage, military, etc. With the development of technology, new application can be continuously appeared to replace the original technology and products, and ultraviolet LEDs have wide market application prospects, for example, ultraviolet LED phototherapy instruments are popular medical instruments in the future, but the technology is still in a growing period.
The development of ultraviolet LEDs has faced a number of unique technical difficulties compared to GaN-based blue LEDs, such as: epitaxial growth of high Al composition AlGaN material is difficult, and in general, the higher the Al composition is, the lower the crystal quality is, and the dislocation density is generally 10 9 ～10 10 /cm 2 Or even higher; this results in dislocations extending into the multiple quantum well active region to form a polarized electric field, so that the recombination probability of electrons and holes is reduced, and the light emission efficiency is lowered. In addition, the luminous efficiency is also reduced due to the existence of a large polarized electric field between the well barriers between the ultraviolet LED multiple quantum well active regions.
Disclosure of Invention
The invention aims to solve the technical problem of providing a light-emitting diode epitaxial wafer and a preparation method thereof, which can improve the luminous efficiency of a light-emitting diode.
In order to solve the problems, the invention discloses a light-emitting diode epitaxial wafer, which comprises a substrate, a buffer layer, an N-type AlGaN layer, a multiple quantum well layer, an electron blocking layer and a P-type AlGaN layer, wherein the buffer layer, the N-type AlGaN layer, the multiple quantum well layer, the electron blocking layer and the P-type AlGaN layer are sequentially laminated on the substrate; the multi-quantum well layer is of a periodic structure, and the period number is more than or equal to 3;
the multi-quantum well layer of each period comprises a quantum barrier layer, a first transition layer, a quantum well layer and a second transition layer which are sequentially stacked;
wherein the quantum barrier layer is Al y Ga 1-y N layer, quantum well layer is Al x Ga 1-x An N layer; x is 0.3-0.5, y is 0.4-0.6, and x is less than y;
the first transition layer comprises a first InN layer and a first AlN layer which are sequentially laminated on the quantum barrier layer;
the second transition layer comprises a second AlN layer and a second InN layer which are sequentially laminated on the quantum well layer.
As an improvement of the technical scheme, the thickness of the quantum well layer is 1.5-5 nm, and the thickness of the quantum barrier layer is 10-20 nm; the cycle number of the multiple quantum well layer is 3-15;
the thickness of the first InN layer is 1 nm-3 nm, and the thickness of the first AlN layer is 1 nm-3 nm;
the thickness of the second InN layer is 1 nm-3 nm, and the thickness of the second AlN layer is 1 nm-3 nm.
As an improvement of the technical proposal, the first InN layer and the second InN layer are doped with Mg with the doping concentration of 1 multiplied by 10 18 cm -3 ～5×10 18 cm -3 。
As an improvement of the technical proposal, the quantum barrier layer is doped with Si, and the doping concentration is 8 multiplied by 10 17 cm -3 ～6×10 18 cm -3 ；
The thickness of the first AlN layer is 2-3 nm, and the thickness of the second AlN layer is 2-3 nm.
As an improvement of the technical scheme, the Al component proportion in the P-type AlGaN layer is smaller than the Al component proportion in the quantum well layer;
the P-type doping element of the P-type AlGaN layer is Mg, and the doping concentration is 3 multiplied by 10 19 cm -3 ～5×10 20 cm -3 The thickness of the P-type AlGaN layer is 150 nm-300 nm.
As an improvement of the technical scheme, the Al component ratio in the N-type AlGaN layer is larger than the Al component ratio in the quantum well layer;
the N-type doping element of the N-type AlGaN layer is Si, and the doping concentration is 5 multiplied by 10 18 cm -3 ～1×10 20 cm -3 The thickness of the N-type AlGaN layer is 1-3 mu m。
As an improvement of the technical scheme, the buffer layer is made of AlN material and has a thickness of 1-4 mu m.
Correspondingly, the invention also discloses a preparation method of the light-emitting diode epitaxial wafer, which is used for preparing the light-emitting diode epitaxial wafer and comprises the following steps:
providing a substrate, and sequentially growing a buffer layer, an N-type AlGaN layer, a multiple quantum well layer, an electron blocking layer and a P-type AlGaN layer on the substrate; the multi-quantum well layer is of a periodic structure, and the period number is more than or equal to 3;
the multi-quantum well layer of each period comprises a quantum barrier layer, a first transition layer, a quantum well layer and a second transition layer which are sequentially stacked;
wherein the quantum barrier layer is Al y Ga 1-y N layer, quantum well layer is Al x Ga 1-x An N layer; x is 0.3-0.5, y is 0.4-0.6, and x is less than y;
the first transition layer comprises a first InN layer and a first AlN layer which are sequentially laminated on the quantum barrier layer;
the second transition layer comprises a second AlN layer and a second InN layer which are sequentially laminated on the quantum well layer.
As an improvement of the technical scheme, the growth temperature of the first InN layer and the second InN layer is 750-820 ℃;
the growth temperature of the first AlN layer and the second AlN layer is 1000-1150 ℃;
the growth temperature of the quantum well layer is 1000-1150 ℃;
the growth temperature of the quantum barrier layer is 1000-1150 ℃.
As an improvement of the technical scheme, the buffer layer is made of AlN material;
the growth temperature is 1200-1300 ℃, and NH is generated in the growth process 3 Is pulse type.
The implementation of the invention has the following beneficial effects:
in the LED epitaxial wafer, the multiple quantum well layers in each period comprise a quantum barrier layer, a first transition layer and a quantum well which are sequentially stackedA layer and a second transition layer; the quantum barrier layer is Al y Ga 1-y N layer, quantum well layer is Al x Ga 1-x An N layer; x is 0.3-0.5, y is 0.4-0.6, and x is less than y; the first transition layer comprises a first InN layer and a first AlN layer which are sequentially laminated on the quantum barrier layer; the second transition layer comprises a second AlN layer and a second InN layer which are sequentially laminated on the quantum well layer. The polarization fields of the trap barriers can be regulated and controlled by introducing the first transition layer and the second transition layer, the reverse polarization electric field in the original quantum trap can be compensated to a certain extent, the QCSE effect caused by spontaneous polarization and piezoelectric polarization of the material is reduced, the wave function overlapping rate of electrons and holes in the quantum trap is improved, and therefore the purpose of improving the internal quantum efficiency is achieved. Meanwhile, the first AlN layer and the second AlN layer are introduced at two sides of the quantum well layer, so that electrons and holes can be effectively limited in the quantum well region, the electrons and the holes can be more effectively compounded, and the luminous efficiency of the light-emitting diode epitaxial wafer is improved.
Drawings
Fig. 1 is a schematic structural diagram of an led epitaxial wafer according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a first transition layer according to an embodiment of the invention;
FIG. 3 is a schematic diagram illustrating a second transition layer according to an embodiment of the invention;
fig. 4 is a flowchart of a method for manufacturing an led epitaxial wafer according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail below in order to make the objects, technical solutions and advantages of the present invention more apparent.
Referring to fig. 1 to 3, the invention discloses a light emitting diode epitaxial wafer, which comprises a substrate 1, a buffer layer 2, an N-type AlGaN layer 3, a multiple quantum well layer 4, an electron blocking layer 5 and a P-type AlGaN layer 6 which are sequentially laminated on the substrate 1; the multiple quantum well layer 4 has a periodic structure, and the multiple quantum well layer 4 of each period includes a quantum barrier layer 41, a first transition layer 42, a quantum well layer 43, and a second transition layer 44, which are sequentially stacked. Wherein the quantum well layer 43 is Al x Ga 1-x N layer (x=0.3 to the whole0.5 With quantum barrier layer 41 of Al y Ga 1-y N layers (y=0.4 to 0.6), and x < y. Preferably, x is 0.3 to 0.4, and exemplary is 0.31, 0.33, 0.35, or 0.37, but is not limited thereto. y is 0.45 to 0.55, and exemplary is 0.48, 0.5, 0.52 or 0.54, but is not limited thereto.
Wherein the cycle number of the multiple quantum well layer 4 is equal to or more than 3, preferably 4 to 15, more preferably 5 to 10.
The first transition layer 42 includes a first InN layer 411 and a first AlN layer 412 sequentially stacked on the quantum barrier layer 41. Among them, the thickness of the first InN layer 411 is 0.5nm to 4nm, and exemplary is 0.8nm, 1.5nm, 2.2nm, 2.9nm, 3.6nm, or 4.3nm, but is not limited thereto. Preferably, the thickness of the first InN layer 411 is 1nm to 3nm. The thickness of the first AlN layer 412 is 0.5nm to 3.5nm, and when the thickness thereof is < 0.5nm, it is difficult to effectively weaken the piezoelectric polarization between the well barriers; when the thickness of the epitaxial wafer is more than 3.5nm, the working voltage of the light-emitting diode epitaxial wafer is easy to rise. The thickness of the first AlN layer 412 is, but not limited to, 0.7nm, 1.2nm, 1.8nm, 2.3nm, 2.8nm, or 3.3nm, for example. Preferably, the thickness of the first AlN layer 412 is 1nm to 3nm.
The second transition layer 44 includes a second AlN layer 441 and a second InN layer 442 sequentially stacked on the quantum well layer 43. Wherein the thickness of the second AlN layer 441 is 0.5nm to 3.5nm, and when the thickness thereof is less than 0.5nm, it is difficult to effectively weaken the piezoelectric polarization between the well barriers; when the thickness of the epitaxial wafer is more than 3.5nm, the working voltage of the light-emitting diode epitaxial wafer is easy to rise. The thickness of the second AlN layer 441 is, but not limited to, 0.7nm, 1.2nm, 1.8nm, 2.3nm, 2.8nm, or 3.3nm, for example. Preferably, the thickness of the second AlN layer 441 is 1nm to 3nm. The thickness of the second InN layer 442 is 0.5nm to 4nm, and exemplary is 0.8nm, 1.5nm, 2.2nm, 2.9nm, 3.6nm, or 4.3nm, but is not limited thereto. Preferably, the thickness of the second InN layer 442 is 1nm to 3nm.
Preferably, in one embodiment of the present invention, the first InN layer 421 and the second InN layer 442 are doped with Mg at a doping concentration of 1×10 18 cm -3 ～5×10 18 cm -3 . By introducing Mg doping, one provides a small amount of holes, so that the quantum well layerThe number of middle holes and electrons is more matched, so that the recombination efficiency is improved, and the luminous efficiency is improved; the two can effectively reduce the working voltage, so that the first AlN layer 422 and the second AlN layer 441 can be thicker, thereby weakening the polarization field better and improving the luminous efficiency. Specifically, the thickness of the first AlN layer 422 and the second AlN layer 441 may be increased to 2nm to 3nm based on this scheme.
Exemplary, the doping concentration of Mg in the first InN layer 421 and the second InN layer 442 is 1.5x10 18 cm -3 、2×10 18 cm -3 、2.5×10 18 cm -3 、3×10 18 cm -3 Or 4X 10 18 cm -3 But is not limited thereto. Preferably, the Mg doping concentration in the first InN layer 421 and the second InN layer 442 is 2×10 18 cm -3 ～5×10 18 cm -3 。
Preferably, in one embodiment of the present invention, the quantum barrier layer 41 is doped with Si at a doping concentration of 8×10 17 cm -3 ～6×10 18 cm -3 Si doping is also beneficial to reducing series resistance and operating voltage. Exemplary, the Si doping concentration in the quantum barrier layer 41 is 9×10 17 cm -3 、2×10 18 cm -3 、3×10 18 cm -3 Or 4X 10 18 cm -3 But is not limited thereto. Preferably 2X 10 18 cm -3 ～5×10 18 cm -3 。
Among them, the substrate 1 is a sapphire substrate, a silicon substrate, or a gallium oxide substrate, but is not limited thereto. Preferably a sapphire substrate or a silicon substrate, more preferably a sapphire substrate.
Among them, the buffer layer 2 is an AlN layer or a low-temperature AlGaN layer, preferably an AlN layer. The thickness of the buffer layer 2 is 1 μm to 4 μm, and exemplary is 1.4 μm, 1.8 μm, 2.2 μm, 2.7 μm, 3.3 μm or 3.8 μm, but is not limited thereto.
Among them, the thickness of the N-type AlGaN layer 3 is 1 μm to 3 μm, and exemplary is 1.4 μm, 1.9 μm, 2.4 μm or 2.8 μm, but not limited thereto. The N-type doping element in the N-type AlGaN layer is Si, but is not limited thereto. N-type doping concentration of 5×10 18 cm -3 ～1×10 20 cm -3 。
Based on this control, the dislocation defect extending from the substrate 1 can be better reduced, the dislocation defect entering the multiple quantum well layer 4 can be reduced, the polarization field can be weakened, and the luminous efficiency can be improved. Preferably, the ratio of the Al component in the N-type AlGaN layer 3 is 0.4 to 0.55, and exemplary is 0.44, 0.47, 0.5, 0.52 or 0.54, but is not limited thereto. Preferably 0.48 to 0.52.
Wherein the electron blocking layer 5 is Al z Ga 1-z The N layer has a Z of 0.6-0.7, and has a higher Al component, so that electron overflow can be effectively blocked, and non-radiative recombination is reduced. The thickness of the modulator blocking layer is 20nm to 80nm, and exemplary is 25nm, 33nm, 41nm, 52nm, 60nm or 70nm, but is not limited thereto.
The thickness of the P-type AlGaN layer 6 is 150nm to 300nm, and 180nm, 210nm, 240nm or 270nm is exemplified, but not limited thereto. The P-type doping element of the P-type AlGaN layer 6 is Mg, but is not limited thereto. The doping concentration is 3×10 19 cm -3 ～5×10 20 cm -3 。
Wherein the Al component ratio in the P-type AlGaN layer 6 is smaller than the Al component ratio in the quantum well layer; based on the control, the doping difficulty of the P-type AlGaN layer 6 can be reduced, and the hole concentration can be improved. Specifically, the Al composition ratio in the P-type AlGaN layer 6 is 0.25 to 0.35, and is exemplified by 0.28, 0.31, or 0.34, but not limited thereto. Preferably 0.28 to 0.33.
Correspondingly, referring to fig. 4, the invention also discloses a preparation method of the light-emitting diode epitaxial wafer, which is used for preparing the light-emitting diode epitaxial wafer and comprises the following steps:
s1: providing a substrate;
s2: sequentially growing a buffer layer, an N-type AlGaN layer, a multiple quantum well layer, an electron blocking layer and a P-type AlGaN layer on a substrate;
specifically, step S2 includes:
s21: growing a buffer layer on a substrate;
wherein the buffer layer may be grown by PVD, MOCVD, MBE or HVPE, but is not limited thereto.
Preferably, in one embodiment of the present invention, the AlN layer is grown by MOCVD as a buffer layer at a growth temperature of 1200-1300 ℃ and NH during growth 3 For pulse-on, in particular NH 3 And (5) introducing the mixture for 20-30 s and stopping for 5-10 s. By the pulse introduction mode, the AlN layer can be prevented from generating cracks, and the crystal quality of the AlN layer is improved, so that lattice mismatch is buffered better.
S22: growing an N-type AlGaN layer on the buffer layer;
among them, the N-type AlGaN layer may be grown by MOCVD, MBE, or HVPE, but is not limited thereto.
Preferably, in one embodiment of the present invention, the N-type AlGaN layer is grown by MOCVD. The growth temperature is 1050-1200 ℃.
S23: growing a multi-quantum well layer on the N-type AlGaN layer;
wherein, step S23 includes the following steps:
s231: growing a quantum barrier layer;
wherein Al can be grown by MOCVD, MBE or HVPE y Ga 1-y The N layer is not limited to this, but serves as a quantum barrier layer.
Preferably, in one embodiment of the invention, al is grown by MOCVD y Ga 1-y The growth temperature of the N layer serving as the quantum barrier layer is 1000-1150 ℃.
S232: growing a first InN layer on the quantum barrier layer;
wherein the first InN layer may be grown by MOCVD, MBE, or HVPE, but is not limited thereto.
Preferably, in one embodiment of the present invention, the first InN layer is grown by MOCVD at a growth temperature of 750 ℃ to 820 ℃.
S233: growing a first AlN layer on the first InN layer;
wherein the first AlN layer may be grown by PVD, MOCVD, MBE or HVPE, but is not limited thereto.
Preferably, in one embodiment of the present invention, the first AlN layer is grown by MOCVD at a growth temperature of 1000 ℃ to 1150 ℃.
S234: growing a quantum well layer on the first AlN layer;
wherein Al can be grown by MOCVD, MBE or HVPE x Ga 1-x The N layer is not limited to this, but is a quantum well layer.
Preferably, in one embodiment of the invention, al is grown by MOCVD x Ga 1-x The growth temperature of the N layer serving as the quantum well layer is 1000-1150 ℃.
S235: growing a second AlN layer on the quantum well layer;
wherein the second AlN layer may be grown by PVD, MOCVD, MBE or HVPE, but is not limited thereto.
Preferably, in one embodiment of the present invention, the second AlN layer is grown by MOCVD at a growth temperature of 1000 ℃ to 1150 ℃.
S236: growing a second InN layer on the second AlN layer;
wherein the second InN layer may be grown by MOCVD, MBE, or HVPE, but is not limited thereto.
Preferably, in one embodiment of the present invention, the second InN layer is grown by MOCVD at a growth temperature of 750 ℃ to 820 ℃.
S237: steps S231 to S236 are periodically repeated until a multi-quantum well layer is obtained.
S24: growing an electron blocking layer on the multiple quantum well layer;
wherein Al can be grown by MOCVD, MBE or HVPE z Ga 1-z And an N layer as an electron blocking layer, but is not limited thereto.
Preferably, in one embodiment of the invention, al is grown by MOCVD z Ga 1-z The growth temperature of the N layer serving as an electron blocking layer is 1050-1200 ℃.
S25: growing a P-type AlGaN layer on the electron blocking layer;
among them, the P-type AlGaN layer may be grown by MOCVD, MBE, or HVPE, but is not limited thereto.
Preferably, in one embodiment of the present invention, the P-type AlGaN layer is grown by MOCVD. The growth temperature is 1000-1150 ℃.
The invention is further illustrated by the following examples:
example 1
Referring to fig. 1 to 3, the present embodiment provides a light emitting diode epitaxial wafer, which includes a substrate 1, a buffer layer 2, an N-type AlGaN layer 3, a multiple quantum well layer 4, an electron blocking layer 5, and a P-type AlGaN layer 6 sequentially stacked on the substrate 1.
Wherein the substrate 1 is a sapphire substrate, the buffer layer 2 is an AlN layer, and the thickness thereof is 1.5 μm. The doping element of the N-type AlGaN layer 3 is Si, and the doping concentration is 1 multiplied by 10 19 cm -3 The thickness thereof was 2.5 μm and the Al component ratio was 0.5.
The multiple quantum well layer 4 is a periodic structure, the period number of which is 5, and the multiple quantum well layer 4 of each period includes a quantum barrier layer 41, a first transition layer 42, a quantum well layer 43 and a second transition layer 44. Wherein the quantum barrier layer 41 is Al y Ga 1-y N layers (y=0.5) with a thickness of 12nm; the first transition layer 42 includes a first InN layer 411 and a first AlN layer 412 sequentially stacked on the quantum barrier layer 41; the thickness of the first InN layer 411 was 2nm, and the thickness of the first AlN layer 412 was 1.5nm. The quantum well layer 43 is Al x Ga 1-x N layers (x=0.35) with a thickness of 2nm. The second transition layer 44 includes a second AlN layer 441 and a second InN layer 442 sequentially stacked on the quantum well layer 43. The thickness of the second AlN layer 441 is 1.5nm, and the thickness of the second InN layer 442 is 2nm.
Wherein the electron blocking layer 5 is Al z Ga 1-z N layers (z=0.65) with a thickness of 25nm. The doping element of the P-type AlGaN layer 6 is Mg, and the doping concentration is 5 multiplied by 10 19 cm -3 The Al component thereof was 0.3 in proportion and 200nm in thickness.
The preparation method of the light-emitting diode epitaxial wafer in the embodiment comprises the following steps:
(1) A substrate is provided.
(2) Growing a buffer layer on a substrate;
wherein the AlN layer is grown by MOCVD, and the growth temperature is 1250 ℃ and NH is obtained during growth 3 Pulse is introduced, namely, firstly introduced for 30 seconds, then closed for 10 seconds, and periodically repeated;
(3) Growing an N-type AlGaN layer on the buffer layer;
wherein, the growth temperature of the N-type AlGaN layer is 1100 ℃ by MOCVD.
(4) Growing a multi-quantum well layer on the N-type AlGaN layer;
the method specifically comprises the following steps:
(I) Growing a quantum barrier layer;
wherein Al is grown by MOCVD y Ga 1-y The growth temperature of the N layer serving as the quantum barrier layer is 1080 ℃.
(II) growing a first InN layer on the quantum barrier layer;
wherein the first InN layer is grown by MOCVD at a growth temperature of 800 ℃.
(III) growing a first AlN layer on the first InN layer;
wherein the first AlN layer is grown by MOCVD at 1080 ℃.
(IV) growing a quantum well layer on the first AlN layer;
wherein Al is grown by MOCVD x Ga 1-x The growth temperature of the N layer serving as the quantum well layer is 1080 ℃.
(V) growing a second AlN layer on the quantum well layer;
wherein the second AlN layer was grown by MOCVD at 1080 ℃.
(VI) growing a second InN layer on the second AlN layer;
wherein the second InN layer is grown by MOCVD at a growth temperature of 800 ℃.
(VII) periodically repeating the steps (I) - (VI) until a multi-quantum well layer is obtained.
(5) Growing an electron blocking layer on the multiple quantum well layer;
wherein Al is grown by MOCVD z Ga 1-z And N layers, which are used as electron blocking layers, and the growth temperature is 1100 ℃.
(6) Growing a P-type AlGaN layer on the electron blocking layer;
wherein the P-type AlGaN layer is grown by MOCVD. The growth temperature is 1080 ℃.
Example 2
The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 1 in that:
the first InN layer 421 and the second InN layer 442 are doped with Mg at a doping concentration of 3.2x10 18 cm -3 . Accordingly, a Mg source (CP is introduced during the preparation of the layer 2 Mg)。
The thickness of each of the first AlN layer 422 and the second AlN layer 441 was 2nm.
The remainder was the same as in example 1.
Example 3
The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 2 in that:
the quantum barrier layer 41 is doped with Si having a doping concentration of 5 x 10 18 cm -3 . Correspondingly, during the preparation of the layer, a Si source (SiH 4 )。
The remainder was the same as in example 2.
Comparative example 1
This comparative example provides a light emitting diode epitaxial wafer, which differs from example 1 in that:
the multi-quantum well layer does not comprise a first transition layer and a second transition layer, and correspondingly, the preparation method also does not comprise the step of preparing the two layers.
The remainder was the same as in example 1.
Comparative example 2
This comparative example provides a light emitting diode epitaxial wafer, which differs from example 1 in that:
the first transition layer and the second transition layer are both Mg-doped InN layers with thickness of 2nm and Mg doping concentration of 3.2X10 18 cm -3 . The first transition layer and the second transition layer were prepared in the same manner as the first InN layer in example 2.
The remainder was the same as in example 1.
Comparative example 3
This comparative example provides a light emitting diode epitaxial wafer, which differs from example 1 in that:
the first transition layer and the second transition layer are all AlN layers with the thickness of 2nm, and the preparation methods of the first transition layer and the second transition layer are the same as those of the first AlN layer in the embodiment 1.
The remainder was the same as in example 1.
The light emitting diode epitaxial wafers obtained in examples 1 to 3 and comparative examples 1 to 3 were tested as follows:
(1) Manufacturing an epitaxial wafer into a 12mil multiplied by 20mil chip, and testing the luminous power, the forward operating voltage and the dominant wavelength of the epitaxial wafer at 100 mA;
(2) And testing comprehensive parameters such as brightness, forward voltage, reverse current, starting voltage, wavelength and the like of each 1000 chips prepared by the method, wherein the chips which are not in a preset value range are unqualified, the rest are qualified, and the yield is counted.
The specific results are shown in the following table:
as can be seen from the table, when the conventional multiple quantum well layer (comparative example 1) is replaced by the multiple quantum well layer (example 1) of the present invention, the light emitting efficiency and yield of the led epitaxial wafer are improved, the operating voltage thereof is reduced, and the main wavelength is maintained to be substantially stable.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of the invention, such changes and modifications are also intended to be within the scope of the invention.
Claims (10)
1. A light-emitting diode epitaxial wafer comprises a substrate, and a buffer layer, an N-type AlGaN layer, a multiple quantum well layer, an electron blocking layer and a P-type AlGaN layer which are sequentially laminated on the substrate; the multi-quantum well layer is of a periodic structure, and the period number is more than or equal to 3;
the multi-quantum well layer of each period comprises a quantum barrier layer, a first transition layer, a quantum well layer and a second transition layer which are sequentially stacked;
wherein the quantum barrier layer is Al y Ga 1-y N layer, quantum well layer is Al x Ga 1-x An N layer; x is 0.3-0.5, y is 0.4-0.6, and x is less than y;
the first transition layer comprises a first InN layer and a first AlN layer which are sequentially laminated on the quantum barrier layer;
the second transition layer comprises a second AlN layer and a second InN layer which are sequentially laminated on the quantum well layer.
2. The light-emitting diode epitaxial wafer of claim 1, wherein the quantum well layer has a thickness of 1.5nm to 5nm and the quantum barrier layer has a thickness of 10nm to 20nm; the cycle number of the multiple quantum well layer is 3-15;
the thickness of the first InN layer is 1 nm-3 nm, and the thickness of the first AlN layer is 1 nm-3 nm;
the thickness of the second InN layer is 1 nm-3 nm, and the thickness of the second AlN layer is 1 nm-3 nm.
3. The led epitaxial wafer of claim 1 or 2, wherein Mg is doped in each of the first InN layer and the second InN layer at a doping concentration of 1×10 18 cm -3 ～5×10 18 cm -3 ；
The thickness of the first AlN layer is 2-3 nm, and the thickness of the second AlN layer is 2-3 nm.
4. The led epitaxial wafer of claim 1 or 2, wherein the quantum barrier layer is doped with Si at a doping concentration of 8 x 10 17 cm -3 ～6×10 18 cm -3 。
5. The light-emitting diode epitaxial wafer of claim 1, wherein the Al composition ratio in the P-type AlGaN layer is smaller than the Al composition ratio in the quantum well layer;
the P-type doping element of the P-type AlGaN layer is Mg, and the doping concentration is 3 multiplied by 10 19 cm -3 ～5×10 20 cm -3 The thickness of the P-type AlGaN layer is 150 nm-300 nm.
6. The light-emitting diode epitaxial wafer of claim 1, wherein the N-type AlGaN layer has a larger Al composition than the quantum well layer;
the N-type doping element of the N-type AlGaN layer is Si, and the doping concentration is 5 multiplied by 10 18 cm -3 ～1×10 20 cm -3 The thickness of the N-type AlGaN layer is 1-3 μm.
7. The led epitaxial wafer of claim 1, wherein the buffer layer is made of AlN and has a thickness of 1 μm to 4 μm.
8. A method for preparing the light-emitting diode epitaxial wafer, which is used for preparing the light-emitting diode epitaxial wafer according to any one of claims 1 to 7, and is characterized by comprising the following steps:
providing a substrate, and sequentially growing a buffer layer, an N-type AlGaN layer, a multiple quantum well layer, an electron blocking layer and a P-type AlGaN layer on the substrate; the multi-quantum well layer is of a periodic structure, and the period number is more than or equal to 3;
the multi-quantum well layer of each period comprises a quantum barrier layer, a first transition layer, a quantum well layer and a second transition layer which are sequentially stacked;
wherein the quantum barrier layer is Al y Ga 1-y N layer, quantum well layer is Al x Ga 1-x An N layer; x is 0.3-0.5, y is 0.4-0.6, and x is less than y;
the first transition layer comprises a first InN layer and a first AlN layer which are sequentially laminated on the quantum barrier layer;
the second transition layer comprises a second AlN layer and a second InN layer which are sequentially laminated on the quantum well layer.
9. The method for manufacturing a light-emitting diode epitaxial wafer according to claim 8, wherein the growth temperature of the first InN layer and the second InN layer is 750-820 ℃;
the growth temperature of the first AlN layer and the second AlN layer is 1000-1150 ℃;
the growth temperature of the quantum well layer is 1000-1150 ℃;
the growth temperature of the quantum barrier layer is 1000-1150 ℃.
10. The method for manufacturing a light-emitting diode epitaxial wafer according to claim 8, wherein the buffer layer is made of AlN;
the growth temperature is 1200-1300 ℃, and NH is generated in the growth process 3 Is pulse type.
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