CN116469976A - LED epitaxial wafer, preparation method thereof and LED - Google Patents

LED epitaxial wafer, preparation method thereof and LED Download PDF

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Publication number
CN116469976A
CN116469976A CN202310438487.0A CN202310438487A CN116469976A CN 116469976 A CN116469976 A CN 116469976A CN 202310438487 A CN202310438487 A CN 202310438487A CN 116469976 A CN116469976 A CN 116469976A
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layer
gan layer
emitting diode
light
epitaxial wafer
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程龙
郑文杰
高虹
刘春杨
胡加辉
金从龙
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Jiangxi Zhao Chi Semiconductor Co Ltd
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Jiangxi Zhao Chi Semiconductor 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
    • H01L33/04—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
    • H01L33/005—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
    • H01L33/10—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 light reflecting structure, e.g. semiconductor Bragg reflector
    • 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
    • H01L33/02—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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Computer Hardware Design (AREA)
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  • Led Devices (AREA)

Abstract

The invention discloses a light-emitting diode epitaxial wafer and a preparation method thereof, and an LED, wherein the light-emitting diode epitaxial wafer comprises a substrate, and a buffer layer, a composite undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer and a P-type GaN layer which are sequentially laminated on the substrate; the composite undoped GaN layer comprises a first intrinsic GaN layer, a reflecting layer and a second intrinsic GaN layer which are sequentially laminated on the buffer layer, wherein the reflecting layer comprises an AlN reflecting layer, an Al reflecting layer and SiO 2 A reflective layer. The light-emitting diode epitaxial wafer provided by the invention can reduce dislocation density, reduce non-radiative recombination of quantum wells,the light extraction efficiency of the light emitting diode is improved, and the light emitting efficiency of the light emitting diode is improved.

Description

LED epitaxial wafer, preparation method thereof and LED
Technical Field
The invention relates to the technical field of photoelectricity, in particular to a light-emitting diode epitaxial wafer, a preparation method thereof and an LED.
Background
An InGaN-based light emitting diode, LED for short, is a semiconductor device capable of converting electric energy into light energy. As a novel illumination light source, the LED lamp has the advantages of small volume, light weight, good directivity, long service life, energy conservation, environmental protection and the like, and has wide application prospect. The LED, which is a novel green light source, will lead the trend of future development in the lighting field with its unique characteristics, and will become a "fourth generation light source" following incandescent lamps, burst lamps, high intensity gas discharge lamps.
At present, the internal quantum efficiency of GaN can reach a very high value due to the improvement of the growth quality of materials and the improvement of the manufacturing process of devices. The internal quantum efficiency of the high-quality LED is over 90 percent, and the internal quantum efficiency of the GaN-based blue LED is over 80 percent, but the luminous efficiency is still lower. Light extraction efficiency becomes a major factor limiting its luminous efficiency.
Due to the large lattice mismatch and the difference of thermal expansion coefficients between the substrate and the GaN, a large number of defects exist in the GaN epitaxial layer, and the radiation recombination efficiency of the quantum well layer is reduced. In addition, the GaN is a high refractive index material, and most of light emitted in the active region of the GaN epitaxial layer can generate total reflection phenomenon at an air interface, is restrained in the LED, and is absorbed and lost after multiple total reflections. Factors that cause light absorption include epitaxial layers, quantum wells, chip electrodes, and substrate absorption, etc., reducing the external quantum efficiency of the LED.
Disclosure of Invention
The invention aims to solve the technical problem of providing a light-emitting diode epitaxial wafer, which can reduce dislocation density, reduce non-radiative recombination of quantum wells, improve light extraction efficiency of a light-emitting diode and improve luminous efficiency of the light-emitting diode.
The invention also aims to provide a preparation method of the light-emitting diode epitaxial wafer, which has simple process and can stably prepare the light-emitting diode epitaxial wafer with good luminous efficiency.
In order to solve the technical problems, the invention provides a light-emitting diode epitaxial wafer, which comprises a substrate, and a buffer layer, a composite undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer and a P-type GaN layer which are sequentially laminated on the substrate;
the composite undoped GaN layer comprises a first intrinsic GaN layer, a reflecting layer and a second intrinsic GaN layer which are sequentially laminated on the buffer layer, wherein the reflecting layer comprises an AlN reflecting layer, an Al reflecting layer and SiO 2 A reflective layer.
In one embodiment, the first intrinsic GaN layer has a thickness of 0.5 μm to 5 μm;
the thickness of the reflecting layer is 10 nm-100 nm;
the thickness of the second intrinsic GaN layer is 0.5-5 μm.
In one embodiment, the AlN reflective layer has a thickness of: thickness of the Al reflective layer: the SiO is 2 Thickness of reflective layer= (1-10): 1: (1-10).
In one embodiment, the AlN reflective layer, al reflective layer and SiO 2 Sequentially laminating the reflecting layers to obtain a periodic layer, wherein the reflecting layer comprises a plurality of periodic layers;
in one embodiment, the reflective layer comprises 1 to 50 of the periodic layers.
In one embodiment, the first intrinsic GaN layer is grown at a temperature of 1000 ℃ to 1200 ℃;
the growth temperature of the second intrinsic GaN layer is 1000-1200 ℃;
the growth temperature of the reflecting layer is 900-1100 ℃.
In one embodiment, the growth atmosphere of the first or second intrinsic GaN layer is N 2 、H 2 And NH 3 A mixed gas in which N 2 、H 2 And NH 3 The gas ratio is1：(1～5)：(1～10)；
The AlN reflecting layer has a growth atmosphere of N 2 And NH 3 Mixed gas, N 2 And NH 3 The gas ratio is (1-5): (1-5);
the growth atmosphere of the Al reflecting layer is N 2 ；
The SiO is 2 The growth atmosphere of the reflecting layer is N 2 And O 2 Mixed gas, N 2 And O 2 The gas ratio is (1-5): (1-5).
In one embodiment, the first intrinsic GaN layer or the reflective layer or the second intrinsic GaN layer is grown at a pressure of 50torr to 300torr.
In order to solve the problems, the invention provides a preparation method of a light-emitting diode epitaxial wafer, which comprises the following steps:
s1, preparing a substrate;
s2, sequentially depositing a buffer layer, a composite undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer and a P-type GaN layer on the substrate;
the composite undoped GaN layer comprises a first intrinsic GaN layer, a reflecting layer and a second intrinsic GaN layer which are sequentially laminated on the buffer layer, wherein the reflecting layer comprises an AlN reflecting layer, an Al reflecting layer and SiO 2 A reflective layer.
Correspondingly, the invention further provides an LED, and the LED comprises the LED epitaxial wafer.
The implementation of the invention has the following beneficial effects:
the invention provides a light-emitting diode epitaxial wafer which is provided with a composite undoped GaN layer with a specific structure, wherein the composite undoped GaN layer comprises a first intrinsic GaN layer, a reflecting layer and a second intrinsic GaN layer which are sequentially laminated on a buffer layer, and the reflecting layer comprises an AlN reflecting layer, an Al reflecting layer and SiO 2 A reflective layer.
First, the first and second intrinsic GaN layers can realize release of compressive stress through stacking faults by adjusting thickness, line defects are reduced, crystal quality is improved, and reverse leakage current is reduced. And reduction of compressive stressThe method is favorable for forming an In-rich luminescence center In the InGaN quantum well, and improves the luminescence intensity of the device. Secondly, gaN is a high refractive index material, light emitted in an active region of the GaN epitaxial layer mostly generates a total reflection phenomenon at an air interface, is bound in the LED, is absorbed and lost after multiple times of total reflection, and greatly reduces the external quantum efficiency of the LED. The deposited reflective layer comprises an AlN reflective layer having a refractive index n=2, an al reflective layer having a refractive index n=1.07, sio 2 A reflective layer having a refractive index n=1.6 lower than that of GaN, further comprising AlN reflective layer, al reflective layer and SiO 2 The reflecting layer forms a superlattice structure, and the high-reflection film formed by alternately superposing high-refractive index materials and low-refractive index materials reduces the absorption of light emitted by the LED by the substrate and improves the light extraction efficiency of the LED. Finally, the light-emitting diode epitaxial wafer provided by the invention can reduce dislocation density, reduce non-radiative recombination of quantum wells, improve light extraction efficiency of the light-emitting diode and improve light-emitting efficiency of the light-emitting diode.
Drawings
Fig. 1 is a schematic structural diagram of an led epitaxial wafer according to the present invention;
fig. 2 is a schematic structural diagram of an electron blocking layer of an led epitaxial wafer according to the present invention;
fig. 3 is a flowchart of a method for preparing an led epitaxial wafer according to the present invention;
fig. 4 is a flowchart of step S2 of the method for manufacturing a light emitting diode epitaxial wafer according to the present invention.
Wherein: substrate 1, buffer layer 2, composite undoped GaN layer 3, N-type GaN layer 4, multiple quantum well layer 5, electron blocking layer 6, P-type GaN layer 7, first intrinsic GaN layer 31, reflective layer 32, second intrinsic GaN layer 33, alN reflective layer 321, al reflective layer 322, and SiO 2 A reflective layer 323.
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.
Unless otherwise indicated or contradicted, terms or phrases used herein have the following meanings:
in the present invention, "preferred" is merely to describe embodiments or examples that are more effective, and it should be understood that they are not intended to limit the scope of the present invention.
In the invention, the technical characteristics described in an open mode comprise a closed technical scheme composed of the listed characteristics and also comprise an open technical scheme comprising the listed characteristics.
In the present invention, the numerical range is referred to, and both ends of the numerical range are included unless otherwise specified.
In order to solve the above problems, the present invention provides a light emitting diode epitaxial wafer, as shown in fig. 1 to 2, comprising a substrate 1, and a buffer layer 2, a composite undoped GaN layer 3, an N-type GaN layer 4, a multiple quantum well layer 5, an electron blocking layer 6, and a P-type GaN layer 7 sequentially stacked on the substrate 1;
the composite undoped GaN layer 3 comprises a first intrinsic GaN layer 31, a reflecting layer 32 and a second intrinsic GaN layer 33 sequentially laminated on the buffer layer 2, wherein the reflecting layer 32 comprises an AlN reflecting layer 321, an Al reflecting layer 322 and SiO 2 A reflective layer 323.
The light-emitting diode epitaxial wafer provided by the invention is provided with the composite undoped GaN layer with a specific structure, and the specific structure of the composite undoped GaN layer is described below.
In one embodiment, the thickness of the first intrinsic GaN layer 31 is 0.5 μm to 5 μm; the thickness of the first intrinsic GaN layer 31 is illustratively 1 μm, 2 μm, 3 μm, 4 μm, but is not limited thereto; the thickness of the second intrinsic GaN33 layer is 0.5-5 mu m; the thickness of the second intrinsic GaN layer 33 is illustratively, but not limited to, 1 μm, 2 μm, 3 μm, 4 μm. Preferably, the thickness of the first intrinsic GaN layer 31 is 1 μm to 1.5 μm; the thickness of the second intrinsic GaN layer 33 is 1 μm to 1.5 μm. First, the thickness of the first intrinsic GaN layer 31 and/or the second intrinsic GaN layer 33 is thicker, and as the thickness increases, compressive stress is released through stacking faults, line defects are reduced, crystal quality is improved, and reverse leakage current is reduced. And the reduction of the compressive stress is beneficial to the formation of an In-rich luminescence center In the InGaN quantum well, and the luminescence intensity of the device is improved.
In one embodiment, the reflective layer 32 has a thickness of 10nm to 100nm; the thickness of the reflective layer 32 is exemplified by, but not limited to, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90 nm; preferably, the thickness of the AlN reflective layer 321: thickness of the Al reflection layer 322: the SiO is 2 Thickness of the reflective layer 323= (1 to 10): 1: (1-10). Under the condition, the light escape efficiency of the light-emitting diode can be improved, and the consumption of light in the epitaxial layer through multiple absorption can be reduced.
Further, in one embodiment, the AlN reflective layer 321, al reflective layer 322 and SiO 2 The reflective layer 323 is sequentially laminated to obtain a periodic layer, and the reflective layer comprises a plurality of periodic layers; preferably, the reflective layer 32 includes 1 to 50 of the periodic layers; more preferably, the reflective layer 32 includes 10 to 30 of the periodic layers.
It should be noted that GaN is a high refractive index material, its refractive index n=2.3, and most of light emitted from the active region of the GaN epitaxial layer will generate total reflection phenomenon at the interface of air, and be bound in the LED, and absorbed and lost after multiple total reflection, so as to greatly reduce the external quantum efficiency of the LED. The deposited reflective layer includes an AlN reflective layer 321 having a refractive index n=2, an al reflective layer 322 having a refractive index n=1.07, sio 2 A reflective layer 323 having a refractive index n=1.6 lower than that of GaN, and further, alN reflective layer 321, al reflective layer 322 and SiO 2 The reflective layers 323 are alternately laminated to form a superlattice structure, and the high-reflection film formed by alternately laminating high-refractive-index materials and low-refractive-index materials reduces absorption of light emitted by the LED by the substrate and improves light extraction efficiency of the LED.
In summary, the light-emitting diode epitaxial wafer with the specific composite undoped GaN layer structure provided by the invention can reduce dislocation density, reduce quantum well non-radiative recombination, improve light extraction efficiency of the light-emitting diode and improve luminous efficiency of the light-emitting diode.
Correspondingly, the invention provides a preparation method of the light-emitting diode epitaxial wafer, as shown in fig. 3, comprising the following steps:
s1, preparing a substrate 1;
in one embodiment, the substrate 1 is a sapphire substrate; sapphire is the most commonly used substrate material at present, and the sapphire substrate has the advantages of mature preparation process, low price, easy cleaning and processing and good stability at high temperature.
S2, sequentially depositing a buffer layer 2, a composite undoped GaN layer 3, an N-type GaN layer, a multiple quantum well layer 5, an electron blocking layer 6 and a P-type GaN layer 7 on the substrate 1.
In one embodiment, as shown in fig. 4, step S2 includes the steps of:
s21, depositing a buffer layer 2 on the substrate 1.
Preferably, an AlN buffer layer is deposited in the PVD (physical vapor deposition) application material, the thickness of the AlN buffer layer is 10-20 nm, the AlN buffer layer provides a nucleation center which is the same as the substrate orientation, stress generated by lattice mismatch between GaN and the substrate and thermal stress generated by thermal expansion coefficient mismatch are released, a flat nucleation surface is provided by further growth, and the contact angle of nucleation growth is reduced, so that island-shaped GaN grains can be connected into a plane in a smaller thickness, and the island-shaped GaN grains are converted into two-dimensional epitaxial growth.
S22, depositing a composite undoped GaN layer 3 on the buffer layer 2.
Preferably, the sapphire substrate plated with the AlN buffer layer is transferred into MOCVD before depositing the composite undoped GaN layer, at H 2 Pretreating the atmosphere for 1-10 min at 1000-1200 ℃; therefore, the crystal quality of the AlN buffer layer can be improved, and the crystal quality of a subsequent deposited GaN epitaxial layer can be effectively improved.
Preferably, the growth temperature of the first intrinsic GaN layer is 1000-1200 ℃;
the growth temperature of the second intrinsic GaN layer is 1000-1200 ℃;
the growth temperature of the reflecting layer is 900-1100 ℃.
Preferably, the growth atmosphere of the first or second intrinsic GaN layer is N 2 、H 2 And NH 3 A mixed gas in which N 2 、H 2 And NH 3 The gas ratio is 1: (1-5): (1-10);
the AlN reflecting layer has a growth atmosphere of N 2 And NH 3 Mixed gas, N 2 And NH 3 The gas ratio is (1-5): (1-5);
the growth atmosphere of the Al reflecting layer is N 2 ；
The SiO is 2 The growth atmosphere of the reflecting layer is N 2 And O 2 Mixed gas, N 2 And O 2 The gas ratio is (1-5): (1-5).
The first or second intrinsic GaN layer is grown in the presence of N 2 、H 2 And NH 3 Mixed gas, introduce H 2 The mobility of Ga is improved, the lateral growth of a GaN epitaxial layer is promoted, and the quality of GaN crystals is improved.
The AlN reflective layer grows in the atmosphere of N 2 And NH 3 Mixed gas without H 2 Reducing Al source and H 2 Side reactions occur, degrading the crystal quality of the AlN layer.
The growth atmosphere of the Al reflecting layer is N 2 The Al source is subjected to pyrolysis to deposit an Al radiation layer.
SiO 2 The growth atmosphere of the reflecting layer is N 2 And O 2 Mixed gas, proper gas proportion to improve SiO 2 Crystal quality of the reflective layer.
Preferably, the growth pressure of the first intrinsic GaN layer or the reflective layer or the second intrinsic GaN layer is 50torr to 300torr.
S23, depositing an N-type GaN layer 4 on the composite undoped GaN layer 3.
Preferably, the growth temperature of the N-type GaN layer is 1050-1200 ℃, the pressure is 100-600 torr, the thickness is 2-3 μm, and the doping concentration of Si is 1X 10 19 atoms/cm 3 ～5×10 19 atoms/cm 3 . The N-type GaN layer provides sufficient electrons for LED luminescence, the resistivity of the N-type GaN layer is higher than that of the transparent electrode on the GaN layer, so that the resistivity of the N-type GaN layer can be effectively reduced due to sufficient Si doping, and in addition, the N-type GaN layer has sufficient thickness to effectively release stressLuminous efficiency of the light emitting diode.
And S24, growing a multi-quantum well layer 5 on the N-type GaN layer 4.
Preferably, the multiple quantum well layers are InGaN quantum well layers and AlGaN quantum barrier layers which are alternately stacked, and the stacking period number is 6-12, wherein the growth temperature of the InGaN quantum well layers is 790-810 ℃, the thickness is 2-5 nm, and the growth pressure is 50-300 torr; the growth temperature of the AlGaN quantum barrier layer is 800-900 ℃, the thickness is 5-15 nm, the growth pressure is 50-300 torr, and the content of Al component is 0.01-0.1. The multi-quantum well layer is an electron and hole composite region, and the reasonable structural design can remarkably increase the overlapping degree of electron and hole wave functions, so that the luminous efficiency of the LED device is improved.
And S25, growing an electron blocking layer 6 on the multi-quantum well layer 5.
Preferably, the electron blocking layer is an AlInGaN layer with the thickness of 10 nm-20 nm, wherein the Al component concentration gradually changes from 0.01 to 0.05 along the growth direction of the epitaxial layer, the in component concentration is 0.01-0.02, the growth temperature is 950-1000 ℃, and the growth pressure is 200-250 torr; therefore, not only can the overflow of electrons be effectively limited, but also the blocking of holes can be reduced, the injection efficiency of the holes to the quantum well is improved, the auger recombination of carriers is reduced, and the luminous efficiency of the light-emitting diode is improved.
And S26, growing a P-type GaN layer 7 on the electron blocking layer 6.
Preferably, the growth temperature of the P-type GaN layer is 900-1050 ℃, the thickness is 10-50 nm, the growth pressure is 100-600 torr, and the doping concentration of Mg is 1X 10 19 atoms/cm 3 ～1×10 21 atoms/cm 3 . Too high a Mg doping concentration can damage the crystal quality, while a lower doping concentration can affect the hole concentration. Meanwhile, for the LED structure with the V-shaped pits, the higher growth temperature of the GaN layer is favorable for combining the V-shaped pits, so that the LED epitaxial wafer with a smooth surface is obtained.
Correspondingly, the invention further provides an LED, and the LED comprises the LED epitaxial wafer. The photoelectric efficiency of the LED is effectively improved, and other items have good electrical properties.
The invention is further illustrated by the following examples:
example 1
The embodiment provides a light-emitting diode epitaxial wafer, which comprises a substrate, and a buffer layer, a composite undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer and a P-type GaN layer which are sequentially laminated on the substrate;
the composite undoped GaN layer comprises a first intrinsic GaN layer, a reflecting layer and a second intrinsic GaN layer which are sequentially laminated on the buffer layer, wherein the reflecting layer comprises an AlN reflecting layer, an Al reflecting layer and SiO 2 A reflective layer.
Wherein the thickness of the first intrinsic GaN layer is 1.5 μm; the thickness of the second intrinsic GaN layer is 1 μm.
The AlN reflecting layer, the Al reflecting layer and the SiO 2 The reflective layer is laminated in sequence to obtain a periodic layer, the reflective layer comprises 20 periodic layers, the thickness of the reflective layer is 50nm, and the thickness of the AlN reflective layer is as follows: thickness of the Al reflective layer: the SiO is 2 Thickness of reflective layer = 2:1:3.
the growth atmosphere of the first or the second intrinsic GaN layer is N 2 、H 2 And NH 3 A mixed gas in which N 2 、H 2 And NH 3 The gas ratio is 1:3:5, a step of;
the AlN reflecting layer has a growth atmosphere of N 2 And NH 3 Mixed gas, N 2 And NH 3 The gas ratio is 2:3, a step of;
the growth atmosphere of the Al reflecting layer is N 2 ；
The SiO is 2 The growth atmosphere of the reflecting layer is N 2 And O 2 Mixed gas, N 2 And O 2 The gas ratio is 2:3.
example 2
The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 1 in that: the thickness of the first intrinsic GaN layer is 1 μm; the thickness of the second intrinsic GaN layer is 0.5 μm; the thickness of the reflective layer was 35nm. 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 1 in that: the thickness of the first intrinsic GaN layer is 2 μm; the thickness of the second intrinsic GaN layer is 1.5 μm; the thickness of the reflective layer was 60nm. The remainder was the same as in example 1.
Example 4
The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 1 in that: thickness of the AlN reflective layer: thickness of the Al reflective layer: the SiO is 2 Thickness of reflective layer = 1:1:3. the remainder was the same as in example 1.
Example 5
The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 1 in that: thickness of the AlN reflective layer: thickness of the Al reflective layer: the SiO is 2 Thickness of reflective layer = 3:1:2. the remainder was the same as in example 1.
Example 6
The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 1 in that: the AlN reflecting layer, the Al reflecting layer and the SiO 2 The reflection layers are sequentially laminated to obtain a periodic layer, and each reflection layer comprises 15 periodic layers. The remainder was the same as in example 1.
Example 7
The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 1 in that: the AlN reflecting layer, the Al reflecting layer and the SiO 2 The reflection layers are sequentially laminated to obtain a periodic layer, and the reflection layers comprise 25 periodic layers. The remainder was the same as in example 1.
Example 8
The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 1 in that: the growth atmosphere of the first or the second intrinsic GaN layer is N 2 、H 2 And NH 3 A mixed gas in which N 2 、H 2 And NH 3 The gas ratio is 1:1:3, a step of; the AlN reflecting layer has a growth atmosphere of N 2 And NH 3 Mixed gas，N 2 And NH 3 The gas ratio is 1:3. the remainder was the same as in example 1.
Example 9
The present embodiment provides a light emitting diode epitaxial wafer, which is different from embodiment 1 in that: the growth atmosphere of the first or the second intrinsic GaN layer is N 2 、H 2 And NH 3 A mixed gas in which N 2 、H 2 And NH 3 The gas ratio is 1:3:3, a step of; the AlN reflecting layer has a growth atmosphere of N 2 And NH 3 Mixed gas, N 2 And NH 3 The gas ratio is 1:1. the remainder was the same as in example 1.
Comparative example 1
This comparative example is different from example 1 in that the undoped GaN layer is a 2.5 μm undoped GaN layer, and the rest is the same as example 1.
The light-emitting diode epitaxial wafers prepared in examples 1 to 9 and comparative example 1 were prepared into 10×24mil chips using the same chip process conditions, 300 LED chips were extracted, and the photoelectric properties of the chips were tested at 120mA/60mA current, and the light efficiency improvement rates of examples 1 to 9 relative to comparative example 1 were calculated, and the specific test results are shown in table 1.
TABLE 1 results of Performance test of LEDs prepared in examples 1 to 9
As can be seen from the above results, the light emitting diode epitaxial wafer provided by the present invention has a composite undoped GaN layer with a specific structure, wherein the composite undoped GaN layer comprises a first intrinsic GaN layer, a reflective layer, and a second intrinsic GaN layer sequentially laminated on the buffer layer, and the reflective layer comprises an AlN reflective layer, an Al reflective layer, and SiO 2 A reflective layer.
First of all,the first and second intrinsic GaN layers can realize release of compressive stress through stacking faults by adjusting thickness, line defects are reduced, crystal quality is improved, and reverse leakage current is reduced. And the reduction of the compressive stress is beneficial to the formation of an In-rich luminescence center In the InGaN quantum well, and the luminescence intensity of the device is improved. Secondly, gaN is a high refractive index material, light emitted in an active region of the GaN epitaxial layer mostly generates a total reflection phenomenon at an air interface, is bound in the LED, is absorbed and lost after multiple times of total reflection, and greatly reduces the external quantum efficiency of the LED. The deposited reflective layer comprises an AlN reflective layer having a refractive index n=2, an al reflective layer having a refractive index n=1.07, sio 2 A reflective layer having a refractive index n=1.6 lower than that of GaN, further comprising AlN reflective layer, al reflective layer and SiO 2 The reflecting layer forms a superlattice structure, and the high-reflection film formed by alternately superposing high-refractive index materials and low-refractive index materials reduces the absorption of light emitted by the LED by the substrate and improves the light extraction efficiency of the LED. Finally, the light-emitting diode epitaxial wafer provided by the invention can reduce dislocation density, reduce non-radiative recombination of quantum wells, improve light extraction efficiency of the light-emitting diode and improve light-emitting efficiency of the light-emitting diode.
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. The light-emitting diode epitaxial wafer is characterized by comprising a substrate, and a buffer layer, a composite undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer and a P-type GaN layer which are sequentially laminated on the substrate;
the composite undoped GaN layer comprises a first intrinsic GaN layer, a reflecting layer and a second intrinsic GaN layer which are sequentially laminated on the buffer layer, wherein the reflecting layer comprises an AlN reflecting layer, an Al reflecting layer and SiO 2 A reflective layer.
2. The light emitting diode epitaxial wafer of claim 1, wherein the first intrinsic GaN layer has a thickness of 0.5 μm to 5 μm;
the thickness of the reflecting layer is 10 nm-100 nm;
the thickness of the second intrinsic GaN layer is 0.5-5 μm.
3. The light-emitting diode epitaxial wafer of claim 1, wherein the AlN reflective layer has a thickness of: thickness of the Al reflective layer: the SiO is 2 Thickness of reflective layer= (1-10): 1: (1-10).
4. The light-emitting diode epitaxial wafer according to claim 1, wherein the AlN reflective layer, the Al reflective layer and SiO 2 The reflective layers are sequentially laminated to obtain a periodic layer, and the reflective layer comprises a plurality of periodic layers.
5. The light-emitting diode epitaxial wafer of claim 1, wherein the reflective layer comprises 1 to 50 of the periodic layers.
6. The light emitting diode epitaxial wafer of claim 1, wherein the first intrinsic GaN layer has a growth temperature of 1000 ℃ to 1200 ℃;
the growth temperature of the second intrinsic GaN layer is 1000-1200 ℃;
the growth temperature of the reflecting layer is 900-1100 ℃.
7. The light-emitting diode epitaxial wafer of claim 1, wherein a growth atmosphere of the first intrinsic GaN layer or the second intrinsic GaN layer is N 2 、H 2 And NH 3 A mixed gas in which N 2 、H 2 And NH 3 The gas ratio is 1: (1-5): (1-10);
the AlN reflecting layer has a growth atmosphere of N 2 And NH 3 Mixed gas, N 2 And NH 3 The gas ratio is (1-5): (1-5);
the Al reflecting layerThe growth atmosphere is N 2 ；
The SiO is 2 The growth atmosphere of the reflecting layer is N 2 And O 2 Mixed gas, N 2 And O 2 The gas ratio is (1-5): (1-5).
8. The light-emitting diode epitaxial wafer of claim 1, wherein a growth pressure of the first intrinsic GaN layer or the reflective layer or the second intrinsic GaN layer is 50torr to 300torr.
9. A method for preparing the light-emitting diode epitaxial wafer according to any one of claims 1 to 8, comprising the steps of:
s1, preparing a substrate;
s2, sequentially depositing a buffer layer, a composite undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an electron blocking layer and a P-type GaN layer on the substrate;
the composite undoped GaN layer comprises a first intrinsic GaN layer, a reflecting layer and a second intrinsic GaN layer which are sequentially laminated on the buffer layer, wherein the reflecting layer comprises an AlN reflecting layer, an Al reflecting layer and SiO 2 A reflective layer.
10. An LED, characterized in that the LED comprises a light emitting diode epitaxial wafer according to any one of claims 1 to 8.
CN202310438487.0A 2023-04-21 2023-04-21 LED epitaxial wafer, preparation method thereof and LED Pending CN116469976A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117153974A (en) * 2023-10-26 2023-12-01 江西兆驰半导体有限公司 LED epitaxial wafer, preparation method thereof and LED

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117153974A (en) * 2023-10-26 2023-12-01 江西兆驰半导体有限公司 LED epitaxial wafer, preparation method thereof and LED
CN117153974B (en) * 2023-10-26 2024-02-20 江西兆驰半导体有限公司 LED epitaxial wafer, preparation method thereof and LED

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