CN112687770B - LED epitaxial growth method - Google Patents
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- 238000000034 method Methods 0.000 title claims abstract description 58
- 229910002704 AlGaN Inorganic materials 0.000 claims abstract description 17
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- 230000004888 barrier function Effects 0.000 claims abstract description 15
- 239000000758 substrate Substances 0.000 claims abstract description 15
- 238000001816 cooling Methods 0.000 claims abstract description 14
- 238000000137 annealing Methods 0.000 claims abstract description 11
- 230000008569 process Effects 0.000 claims description 24
- 229910052594 sapphire Inorganic materials 0.000 claims description 11
- 239000010980 sapphire Substances 0.000 claims description 11
- 230000001788 irregular Effects 0.000 claims description 6
- 125000004429 atom Chemical group 0.000 claims description 5
- 125000004430 oxygen atom Chemical group O* 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 4
- 230000003247 decreasing effect Effects 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 2
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- 239000010410 layer Substances 0.000 description 119
- XCZXGTMEAKBVPV-UHFFFAOYSA-N trimethylgallium Chemical compound C[Ga](C)C XCZXGTMEAKBVPV-UHFFFAOYSA-N 0.000 description 29
- 239000011777 magnesium Substances 0.000 description 20
- IBEFSUTVZWZJEL-UHFFFAOYSA-N trimethylindium Chemical compound C[In](C)C IBEFSUTVZWZJEL-UHFFFAOYSA-N 0.000 description 7
- 239000007789 gas Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 5
- 239000000463 material Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
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- 238000000407 epitaxy Methods 0.000 description 2
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- 239000002096 quantum dot Substances 0.000 description 2
- 230000002829 reductive effect Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000002834 transmittance Methods 0.000 description 2
- 230000005428 wave function Effects 0.000 description 2
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical group [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000013256 coordination polymer Substances 0.000 description 1
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- 238000005265 energy consumption Methods 0.000 description 1
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- 229910052733 gallium Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
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- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
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Abstract
The application discloses an LED epitaxial growth method, which sequentially comprises the following steps: the method comprises the steps of processing a substrate, growing a low-temperature GaN buffer layer, growing an undoped GaN layer, growing an N-type GaN layer doped with Si, growing a multi-quantum well layer, growing an AlGaN electron blocking layer and growing a P-type GaN layer doped with Mg, and cooling, wherein the growing of the multi-quantum well layer sequentially comprises the steps of In-doping pretreatment, growing an InGaN well layer, ga 2O3 pre-growth, growing a Ga 2O3 layer, annealing treatment, growing a GaN graded layer and growing a GaN barrier layer. The method solves the problems of low growth quality of the quantum well and low radiation recombination efficiency of the quantum well existing in the conventional LED epitaxial growth method, thereby improving the luminous efficiency of the LED.
Description
Technical Field
The invention belongs to the technical field of LEDs, and particularly relates to an LED epitaxial growth method.
Background
A Light-Emitting Diode (LED) is a semiconductor electronic device that converts electrical energy into Light energy. When current flows through the LED, electrons and holes in the LED are recombined in the multiple quantum wells of the LED to emit monochromatic light. The LED is used as a novel high-efficiency, environment-friendly and green solid-state lighting source, and has the advantages of low voltage, low energy consumption, small volume, light weight, long service life, high reliability, rich colors and the like. At present, the scale of producing LEDs in China is gradually expanding, but the LEDs still have the problem of low luminous efficiency, and the energy-saving effect of the LEDs is affected.
The quality of the LED epitaxial InGaN/GaN multi-quantum well prepared by the existing LED multi-quantum well growth method is low, the radiation efficiency of the multi-quantum well light-emitting region is low, the improvement of the light-emitting efficiency of the LED is seriously hindered, and the energy-saving effect of the LED is influenced.
In view of the above, there is an urgent need to develop a new method for epitaxial growth of LEDs, which solves the problems of low growth quality and low radiation recombination efficiency of the quantum wells of the existing LEDs, thereby improving the light-emitting efficiency of the LEDs.
Disclosure of Invention
The invention solves the problems of low quantum well growth quality and low quantum well radiation recombination efficiency existing in the existing LED epitaxial growth method by adopting a novel multi-quantum well layer growth method, thereby improving the luminous efficiency of the LED.
The LED epitaxial growth method sequentially comprises the following steps: treating a substrate, growing a low-temperature GaN buffer layer, growing an undoped GaN layer, growing an Si-doped N-type GaN layer, growing a multi-quantum well layer, growing an AlGaN electron blocking layer, growing an Mg-doped P-type GaN layer, and cooling; wherein growing the multiple quantum well layer sequentially comprises: wherein growing the multiple quantum well layer sequentially comprises: the preparation method comprises the following specific steps of In-doped pretreatment, inGaN well layer growth, ga 2O3 pre-growth, ga 2O3 layer growth, annealing treatment, gaN graded layer growth and GaN barrier layer growth:
A. Controlling the pressure of the reaction cavity at 200-280mbar, controlling the temperature of the reaction cavity at 800-850 ℃, introducing NH 3 and TMIn, and carrying out In doping pretreatment for 10-20 seconds;
B. The pressure of the reaction cavity is kept unchanged, the temperature of the reaction cavity is increased to 900-950 ℃, NH 3, TMGa and TMIn are introduced, and an InGaN well layer with the thickness of 3-5nm is grown;
C. Keeping the pressure of the reaction cavity unchanged, reducing the temperature of the reaction cavity to 600-650 ℃, introducing NH 3、TMGa、O2 and N 2, performing 60-80 seconds Ga 2O3 pre-growth, and controlling the molar content of O atoms to be uniformly increased from 15% to 30% in the pre-growth process;
D. Keeping the pressure of the reaction cavity unchanged, raising the temperature of the reaction cavity to 800-840 ℃, introducing NH 3、TMGa、O2 and N 2, and growing a Ga 2O3 layer with the thickness of 10-15 nm;
E. Maintaining the pressure of the reaction cavity unchanged, reducing the temperature of the reaction cavity to 700-750 ℃, introducing O 2 and N 2 for annealing treatment of 60-80S, wherein the flow ratio of the introduced gas is N 2:O2 = 200:35sccm;
F. Raising the temperature of the reaction cavity to 850 ℃, raising the pressure of the reaction cavity to 300mbar, introducing NH 3、TMGa、N2 and SiH 4, growing a GaN graded layer with the thickness of 5-8nm, controlling the doping concentration of Si to gradually decrease from 1E22atom/cm 3 to 1E21 atom/cm 3 in the growing process, gradually decreasing the temperature from 850 ℃ to 780 ℃, and gradually increasing the pressure of the reaction cavity from 300mbar to 450mbar;
G. Reducing the temperature to 800 ℃, keeping the pressure of the reaction cavity at 300-400mbar, introducing NH 3 with the flow rate of 50000-70000sccm, TMGa with the flow rate of 20-100sccm and N 2 with the flow rate of 100-130L/min, and growing a GaN barrier layer with the thickness of 10 nm;
Repeating the steps A-G, and periodically and sequentially carrying out the steps of In-doped pretreatment, inGaN well layer growth, ga 2O3 pre-growth, ga 2O3 layer growth, annealing treatment, gaN graded layer growth and GaN barrier layer growth, wherein the number of cycles is 2-12.
Preferably, the specific process of processing the substrate is as follows:
And (3) introducing H 2 of 100-130L/min at the temperature of 1000-1100 ℃, maintaining the pressure of the reaction cavity at 100-300mbar, and treating the sapphire substrate for 5-10min.
Preferably, the specific process of growing the low-temperature GaN buffer layer is as follows:
cooling to 500-600 ℃, maintaining the pressure of the reaction cavity at 300-600mbar, introducing NH 3 with the flow rate of 10000-20000sccm, TMGa with the flow rate of 50-100sccm and H 2 with the flow rate of 100-130L/min, and growing a low-temperature GaN buffer layer with the thickness of 20-40nm on the sapphire substrate;
Raising the temperature to 1000-1100 ℃, maintaining the pressure of the reaction cavity at 300-600mbar, introducing NH 3 with the flow rate of 30000-40000sccm and H 2 with the flow rate of 100-130L/min, preserving heat for 300-500s, and corroding the low-temperature GaN buffer layer into an irregular island shape.
Preferably, the specific process of growing the undoped GaN layer is as follows:
Raising the temperature to 1000-1200 ℃, keeping the pressure of the reaction cavity at 300-600mbar, introducing NH 3 with the flow rate of 30000-40000sccm, TMGa with the flow rate of 200-400sccm and H 2 with the flow rate of 100-130L/min, and continuously growing a 2-4 mu m undoped GaN layer.
Preferably, the specific process of growing the Si-doped GaN layer is as follows:
maintaining the pressure of the reaction cavity at 300-600mbar, maintaining the temperature at 1000-1200 ℃, introducing NH 3 with the flow rate of 30000-60000sccm, TMGa with the flow rate of 200-400sccm, H 2 with the flow rate of 100-130L/min and SiH 4 with the flow rate of 20-50sccm, and continuously growing N-type GaN doped with Si with the doping concentration of 3m-4 μm, wherein the doping concentration of Si is 5E18-5E19atoms/cm 3.
Preferably, the specific process of growing the AlGaN electron blocking layer is as follows:
And growing the AlGaN electron blocking layer under the conditions of 900-950 ℃, reaction cavity pressure of 200-400mbar, NH 3 with 500-70000 sccm, TMGa with 30-60sccm, H 2 with 100-130L/min, TMAL with 100-130sccm and Cp 2 Mg with 1000-1300sccm, wherein the thickness of the AlGaN electron blocking layer is 40-60nm, and the doping concentration of Mg is 1E19-1E20atoms/cm 3.
Preferably, the specific process of growing the P-type GaN layer doped with Mg is as follows:
Maintaining the pressure of the reaction cavity at 400-900mbar and the temperature at 950-1000 ℃, introducing NH 3 with the flow rate of 50000-70000sccm, TMGa with the flow rate of 20-100sccm, H 2 with the flow rate of 100-130L/min and Cp 2 Mg with the flow rate of 1000-3000sccm, and continuously growing a 50-200nm P-type GaN layer doped with Mg, wherein the doping concentration of Mg is 1E19-1E20atoms/cm 3.
Preferably, the specific process of cooling is as follows:
Cooling to 650-680 deg.C, maintaining the temperature for 20-30min, closing the heating system, closing the gas supply system, and cooling with furnace.
Compared with the traditional growth method, the LED epitaxial growth method provided by the invention achieves the following effects:
1. In the growth process of the multi-quantum well layer, in doping pretreatment is firstly carried out, so that the surface of a GaN potential barrier is rough, the growth of an InGaN potential well is influenced, the transverse growth of InGaN is restrained, the three-dimensional growth of the InGaN is promoted, the number of quantum dots In the InGaN is increased, and the luminous efficiency of an LED chip is improved.
2. The Ga 2O3 layer is regrown after the InGaN well layer is grown, so that the number of electrons in an active region of the quantum well can be increased, the overlapping integral of wave functions of electrons and holes is improved, the recombination efficiency of the electrons and the holes is improved, and the internal quantum efficiency of the LED is improved. The Ga 2O3 layer pre-growth is carried out before the Ga 2O3 layer is grown, the mole content of O atoms is uniformly increased In the process, so that the film quality of the Ga 2O3 layer grown subsequently is improved, the surface morphology of the material can be changed, the surface mobility of In atoms is improved, the optical quality is improved, and the luminous efficiency of the LED is improved. Through annealing treatment, the light transmittance of the Ga 2O3 layer can be improved, and the resistance of the Ga 2O3 layer is reduced, so that the current expansion is facilitated.
3. According to the multi-quantum well layer, the GaN gradual change layer is grown before the GaN barrier layer is grown, and the temperature, the pressure and the doping concentration of Si are uniformly changed, so that the distribution central axes of holes and electrons in the multi-quantum well are overlapped, the efficiency of electron-hole transition is improved, and the luminous efficiency of the LED chip is improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:
FIG. 1 is a schematic diagram of an LED epitaxy structure prepared by the method of the present invention;
fig. 2 is a schematic structural diagram of an LED epitaxy prepared by a conventional method;
Wherein, 1, a sapphire substrate, 2, a low-temperature GaN buffer layer, 3, an undoped GaN layer, 4, an N-type GaN layer, 5, a multiple quantum well layer, 6, an AlGaN electron blocking layer, 7, a P-type GaN layer, 51, an InGaN well layer, 52, a Ga 2O3 layer, 53, a GaN graded layer, 54 and a GaN barrier layer.
Detailed Description
Certain terms are used throughout the description and claims to refer to particular components. Those of skill in the art will appreciate that a hardware manufacturer may refer to the same component by different names. The description and claims do not take the form of an element differentiated by name, but rather by functionality. As used throughout the specification and claims, the word "comprise" is an open-ended term, and thus should be interpreted to mean "include, but not limited to. By "substantially" is meant that within an acceptable error range, a person skilled in the art is able to solve the technical problem within a certain error range, substantially achieving the technical effect. The description hereinafter sets forth a preferred embodiment for practicing the application, but is not intended to limit the scope of the application, as the description is given for the purpose of illustrating the general principles of the application. The scope of the application is defined by the appended claims.
In addition, the present specification does not limit the components and method steps disclosed in the claims to the components and method steps of the embodiments. In particular, the dimensions, materials, shapes, the structural order, the adjacent order, the manufacturing method, and the like of the structural members described in the embodiments are merely illustrative examples without limiting the scope of the present invention. The size and positional relationship of the structural components shown in the drawings are exaggerated for clarity of illustration.
The present application will be described in further detail below with reference to the drawings, but is not limited thereto.
Example 1
According to the LED epitaxial growth method provided by the embodiment of the invention, the GaN-based LED epitaxial wafer is grown by MOCVD, high-purity H 2 or high-purity N 2 or mixed gas of high-purity H 2 and high-purity N 2 is used as carrier gas, high-purity NH 3 is used as an N source, metal organic source trimethylgallium (TMGa) is used as a gallium source, trimethylindium (TMIn) is used as an indium source, N-type dopant is silane (SiH 4), trimethylaluminum (TMAL) is used as an aluminum source, P-type dopant is magnesium cyclopentadienyl (CP 2 Mg), and the reaction pressure is between 70mbar and 600 mbar. The specific growth mode is as follows (see fig. 1 for epitaxial structure):
The LED epitaxial growth method sequentially comprises the following steps: treating a sapphire substrate 1, growing a low-temperature GaN buffer layer 2, growing an undoped GaN layer 3, growing an Si-doped N-type GaN layer 4, growing a multi-quantum well layer 5, growing an AlGaN electron blocking layer 6, growing an Mg-doped P-type GaN layer 7, and cooling; wherein,
Step 1: the sapphire substrate 1 is processed.
Specifically, the step 1 is further that:
The sapphire substrate is processed for 5 to 10 minutes under the conditions that the temperature is 1000 to 1100 ℃, the pressure of a reaction cavity is 100 to 300mbar and H 2 of 100 to 130L/min is introduced.
Step 2: and growing a low-temperature GaN buffer layer 2, and forming irregular islands on the low-temperature GaN buffer layer 2.
Specifically, the step 2 is further that:
Under the conditions that the temperature is 500-600 ℃, the pressure of a reaction cavity is 300-600mbar, 10000-20000sccm of NH 3, 50-100sccm of TMGa and 100-130L/min of H 2 are introduced, the low-temperature GaN buffer layer 2 is grown on the sapphire substrate 1, and the thickness of the low-temperature GaN buffer layer 2 is 20-40nm;
And forming the irregular island on the low-temperature GaN buffer layer 2 under the conditions that the temperature is 1000-1100 ℃, the pressure of a reaction cavity is 300-600mbar, and 30000-40000sccm of NH 3 and 100-130L/min of H 2 are introduced.
Step 3: an undoped GaN layer 3 is grown.
Specifically, the step 3 is further:
The undoped GaN layer 3 is grown under the conditions that the temperature is 1000-1200 ℃, the pressure of a reaction cavity is 300-600mbar, and 30000-40000sccm of NH 3, 200-400sccm of TMGa and 100-130L/min of H 2 are introduced; the thickness of the undoped GaN layer 3 is 2-4 μm.
Step 4: a Si doped N-type GaN layer 4 is grown.
Specifically, the step 4 is further:
The pressure of the reaction cavity is kept at 300-600mbar, the temperature is kept at 1000-1200 ℃, NH 3 with the flow rate of 30000-60000sccm, TMGa with the flow rate of 200-400sccm, H 2 with the flow rate of 100-130L/min and SiH 4 with the flow rate of 20-50sccm are introduced, and an N-type GaN layer 4 doped with Si with the concentration of 3-4 μm is continuously grown, wherein the doping concentration of Si is 5E18atoms/cm 3-1E19atoms/cm3.
Step 5: a multiple quantum well layer 5 is grown.
The growing multiple quantum well layer 5 further comprises:
A. Controlling the pressure of the reaction cavity at 200-280mbar, controlling the temperature of the reaction cavity at 800-850 ℃, introducing NH 3 and TMIn, and carrying out In doping pretreatment for 10-20 seconds;
B. The pressure of the reaction cavity is kept unchanged, the temperature of the reaction cavity is increased to 900-950 ℃, NH 3, TMGa and TMIn are introduced, and an InGaN well layer 51 with the thickness of 3-5nm is grown;
C. Keeping the pressure of the reaction cavity unchanged, reducing the temperature of the reaction cavity to 600-650 ℃, introducing NH 3、TMGa、O2 and N 2, performing 60-80 seconds Ga 2O3 pre-growth, and controlling the molar content of O atoms to be uniformly increased from 15% to 30% in the pre-growth process;
D. Keeping the pressure of the reaction cavity unchanged, raising the temperature of the reaction cavity to 800-840 ℃, introducing NH 3、TMGa、O2 and N 2, and growing a Ga 2O3 layer 52 with the thickness of 10-15 nm;
E. Maintaining the pressure of the reaction cavity unchanged, reducing the temperature of the reaction cavity to 700-750 ℃, introducing O 2 and N 2 for annealing treatment of 60-80S, wherein the flow ratio of the introduced gas is N 2:O2 = 200:35sccm;
F. Raising the temperature of the reaction chamber to 850 ℃, raising the pressure of the reaction chamber to 300mbar, introducing NH 3、TMGa、N2 and SiH 4, growing a 5-8nm GaN graded layer 53, controlling the doping concentration of Si to gradually decrease from 1E22atom/cm 3 to 1E21 atom/cm 3 in the growing process, gradually decreasing the temperature from 850 ℃ to 780 ℃, and gradually increasing the pressure of the reaction chamber from 300mbar to 450mbar;
G. Reducing the temperature to 800 ℃, keeping the pressure of the reaction cavity at 300-400mbar, introducing NH 3 with the flow rate of 50000-70000sccm, TMGa with the flow rate of 20-100sccm and N 2 with the flow rate of 100-130L/min, and growing a GaN barrier layer 54 with the flow rate of 10 nm;
repeating the steps A-G, and periodically and sequentially carrying out the steps of In-doped pretreatment, growth of InGaN well layer 51, ga 2O3 pre-growth, growth of Ga 2O3 layer 52, annealing treatment, growth of GaN graded layer 53 and growth of GaN barrier layer 54, wherein the number of periods is 2-12.
Step 6: an AlGaN electron blocking layer 6 is grown.
Specifically, the step 6 is further:
The AlGaN electron blocking layer 6 is grown under the conditions that the temperature is 900-950 ℃, the pressure of a reaction cavity is 200-400mbar, NH 3 with the concentration of 50000-70000sccm, TMGa with the concentration of 30-60sccm, H 2 with the concentration of 100-130L/min, TMAL with the concentration of 100-130sccm and Cp 2 Mg with the concentration of 1000-1300sccm are introduced, the thickness of the AlGaN electron blocking layer is 40-60nm, and the doping concentration of Mg is 1E19-1E20atoms/cm 3.
Step 7: a Mg doped P-type GaN layer 7 is grown.
Specifically, the step 7 is further:
Under the conditions of temperature of 950-1000 ℃, reaction cavity pressure of 400-900mbar, NH 3 with 500-70000 sccm, TMGa with 20-100sccm, H 2 with 100-130L/min and Cp 2 Mg with 1000-3000sccm, a Mg doped P-type GaN layer 7 with thickness of 50-200nm is grown, and the Mg doping concentration is 1E19-1E20atoms/cm 3.
Step 8: preserving heat at 650-680 deg.C for 20-30min, closing heating system, closing gas supply system, and cooling with furnace.
Example 2
A comparative example, a conventional method of growing an LED epitaxial structure (see fig. 2 for an epitaxial structure), is provided below.
Step 1: the sapphire substrate is processed for 5 to 10 minutes under the conditions that the temperature is 1000 to 1100 ℃, the pressure of a reaction cavity is 100 to 300mbar and H 2 of 100 to 130L/min is introduced.
Step 2: and growing a low-temperature GaN buffer layer, and forming irregular islands on the low-temperature GaN buffer layer 2.
Specifically, the step 2 is further that:
Under the conditions that the temperature is 500-600 ℃, the pressure of a reaction cavity is 300-600mbar, 10000-20000sccm of NH 3, 50-100sccm of TMGa and 100-130L/min of H 2 are introduced, the low-temperature GaN buffer layer 2 is grown on the sapphire substrate 1, and the thickness of the low-temperature GaN buffer layer 2 is 20-40nm;
And forming the irregular island on the low-temperature GaN buffer layer 2 under the conditions that the temperature is 1000-1100 ℃, the pressure of a reaction cavity is 300-600mbar, NH 3 of 30000-40000sccm and H 2 of 100-130L/min are introduced.
Step 3: an undoped GaN layer 3 is grown.
Specifically, the step 3 is further:
Introducing 30000-40000sccm of NH 3, 200-400sccm of TMGa and 100-130L/min of H 2 into a reaction chamber at 1000-1200 ℃ under the pressure of 300-600 mbar; the thickness of the undoped GaN layer 3 is 2-4 μm.
Step 4: a Si doped N-type GaN layer 4 is grown.
Specifically, the step 4 is further:
And growing an Si doped N-type GaN layer 4 under the conditions that the temperature is 1000-1200 ℃, the pressure of a reaction cavity is 300-600mbar, 30000-60000sccm of NH 3, 200-400sccm of TMGa, 100-130L/min of H 2 and 20-50sccm of SiH 4 are introduced, the thickness of the N-type GaN is 3-4 mu m, and the Si doping concentration is 5E18-1E19atoms/cm 3.
Step 5: an InGaN/GaN multiple quantum well layer 5 is grown.
Specifically, the growing multiple quantum well layer 5 is further:
Maintaining the pressure of the reaction cavity at 300-400mbar and the temperature at 720 ℃, introducing NH 3 with the flow rate of 50000-70000sccm, TMGa with the flow rate of 20-40sccm, TMIn with the flow rate of 10000-15000sccm and N 2 with the flow rate of 100-130L/min, and growing an InGaN well layer 51 with the thickness of 3nm doped with In;
Raising the temperature to 800 ℃, keeping the pressure of the reaction cavity at 300-400mbar, introducing NH 3 with the flow rate of 50000-70000sccm, TMGa with the flow rate of 20-100sccm and N 2 with the flow rate of 100-130L/min, and growing a GaN barrier layer 54 with the flow rate of 10 nm;
and repeatedly and alternately growing the InGaN well layer 51 and the GaN barrier layer 54 to obtain the InGaN/GaN multi-quantum well light-emitting layer, wherein the number of the alternately growing periods of the InGaN well layer 51 and the GaN barrier layer 54 is 7-13.
Step 6: an AlGaN electron blocking layer 6 is grown.
Specifically, the step 6 is further:
The AlGaN electron blocking layer 6 is grown under the conditions that the temperature is 900-950 ℃, the pressure of a reaction cavity is 200-400mbar, 50000-70000sccm of NH 3, 30-60sccm of TMGa, 100-130L/min of H 2, 100-130sccm of TMAL and 1000-1300sccm of Cp 2 Mg are introduced, the thickness of the AlGaN layer 6 is 40-60nm, and the doping concentration of Mg is 1E19-1E20atoms/cm 3.
Step 7: a Mg doped P-type GaN layer 7 is grown.
Specifically, the step 7 is further:
Under the conditions of temperature of 950-1000 ℃, reaction cavity pressure of 400-900mbar, NH 3 with 500-70000 sccm, TMGa with 20-100sccm, H 2 with 100-130L/min and Cp 2 Mg with 1000-3000sccm, a Mg doped P-type GaN layer 7 with thickness of 50-200nm is grown, and the Mg doping concentration is 1E19-1E20atoms/cm 3.
Step 8: preserving heat at 650-680 deg.C for 20-30min, closing heating system, closing gas supply system, and cooling with furnace.
Sample 1 and sample 2 were prepared according to the above examples 1 and 2, respectively, with the ITO layer plated at about 150nm under the same pre-process conditions, the Cr/Pt/Au electrode plated at about 1500nm under the same conditions, the protective layer plated at about 100nm of SiO 2 under the same conditions, then the samples were ground and cut into 635 μm (25 mil) chip particles under the same conditions, after which the sample 1 and sample 2 were each picked up at 1000 grains at the same position and packaged into white LEDs under the same packaging process. The photoelectric properties of sample 1 and sample 2 were tested using an integrating sphere under a drive current of 350 mA.
Table 1 results of comparing electrical parameters of samples 1 and 2
As can be seen from table 1, the light-emitting efficiency of the LED (sample 1) prepared by the method for epitaxial growth of the present invention is obviously improved, and the electrical parameters of other LEDs such as voltage, reverse voltage, electric leakage, antistatic ability, etc. are better, because the technical scheme of the present invention solves the problems of low quantum well growth quality and low quantum well radiation recombination efficiency existing in the existing LED, thereby improving the light-emitting efficiency of the LED, and improving the photoelectric performance of other LEDs.
The LED epitaxial growth method achieves the following effects:
1. In the growth process of the multi-quantum well layer, in doping pretreatment is firstly carried out, so that the surface of a GaN potential barrier is rough, the growth of an InGaN potential well is influenced, the transverse growth of InGaN is restrained, the three-dimensional growth of the InGaN is promoted, the number of quantum dots In the InGaN is increased, and the luminous efficiency of an LED chip is improved.
2. The Ga 2O3 layer is regrown after the InGaN well layer is grown, so that the number of electrons in an active region of the quantum well can be increased, the overlapping integral of wave functions of electrons and holes is improved, the recombination efficiency of the electrons and the holes is improved, and the internal quantum efficiency of the LED is improved. The Ga 2O3 layer pre-growth is carried out before the Ga 2O3 layer is grown, the mole content of O atoms is uniformly increased In the process, so that the film quality of the Ga 2O3 layer grown subsequently is improved, the surface morphology of the material can be changed, the surface mobility of In atoms is improved, the optical quality is improved, and the luminous efficiency of the LED is improved. Through annealing treatment, the light transmittance of the Ga 2O3 layer can be improved, and the resistance of the Ga 2O3 layer is reduced, so that the current expansion is facilitated.
3. According to the multi-quantum well layer, the GaN gradual change layer is grown before the GaN barrier layer is grown, and the temperature, the pressure and the doping concentration of Si are uniformly changed, so that the distribution central axes of holes and electrons in the multi-quantum well are overlapped, the efficiency of electron-hole transition is improved, and the luminous efficiency of the LED chip is improved.
Since the method section has already described the embodiments of the present application in detail, the description of the structures and the corresponding parts of the methods related in the embodiments is omitted, and the description is omitted. Reference is made to the description of the method embodiments for specific details of construction and are not specifically defined herein.
While the foregoing description illustrates and describes the preferred embodiments of the present application, it is to be understood that the application is not limited to the forms disclosed herein, but is not to be construed as limited to other embodiments, and is capable of numerous other combinations, modifications and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein, either as a result of the foregoing teachings or as a result of the knowledge or technology of the relevant art. And that modifications and variations which do not depart from the spirit and scope of the application are intended to be within the scope of the appended claims.
Claims (8)
1. An LED epitaxial growth method, comprising, in order: treating a substrate, growing a low-temperature GaN buffer layer, growing an undoped GaN layer, growing an Si-doped N-type GaN layer, growing a multi-quantum well layer, growing an AlGaN electron blocking layer, growing an Mg-doped P-type GaN layer, and cooling; the method is characterized in that the multi-quantum well layer is grown in sequence, and the method comprises the following steps: the preparation method comprises the following specific steps of In-doped pretreatment, inGaN well layer growth, ga 2O3 pre-growth, ga 2O3 layer growth, annealing treatment, gaN graded layer growth and GaN barrier layer growth:
A. Controlling the pressure of the reaction cavity at 200-280mbar, controlling the temperature of the reaction cavity at 800-850 ℃, introducing NH 3 and TMIn, and carrying out In doping pretreatment for 10-20 seconds;
B. The pressure of the reaction cavity is kept unchanged, the temperature of the reaction cavity is increased to 900-950 ℃, NH 3, TMGa and TMIn are introduced, and an InGaN well layer with the thickness of 3-5nm is grown;
C. Keeping the pressure of the reaction cavity unchanged, reducing the temperature of the reaction cavity to 600-650 ℃, introducing NH 3、TMGa、O2 and N 2, performing 60-80 seconds Ga 2O3 pre-growth, and controlling the molar content of O atoms to be uniformly increased from 15% to 30% in the pre-growth process;
D. Keeping the pressure of the reaction cavity unchanged, raising the temperature of the reaction cavity to 800-840 ℃, introducing NH 3、TMGa、O2 and N 2, and growing a Ga 2O3 layer with the thickness of 10-15 nm;
E. Maintaining the pressure of the reaction cavity unchanged, reducing the temperature of the reaction cavity to 700-750 ℃, introducing O 2 and N 2 for annealing treatment of 60-80S, wherein the flow ratio of the introduced gas is N 2:O2 = 200:35sccm;
F. Raising the temperature of the reaction cavity to 850 ℃, raising the pressure of the reaction cavity to 300mbar, introducing NH 3、TMGa、N2 and SiH 4, growing a GaN graded layer with the thickness of 5-8nm, controlling the doping concentration of Si to gradually decrease from 1E22atom/cm 3 to 1E21 atom/cm 3 in the growing process, gradually decreasing the temperature from 850 ℃ to 780 ℃, and gradually increasing the pressure of the reaction cavity from 300mbar to 450mbar;
G. Reducing the temperature to 800 ℃, keeping the pressure of the reaction cavity at 300-400mbar, introducing NH 3 with the flow rate of 50000-70000sccm, TMGa with the flow rate of 20-100sccm and N 2 with the flow rate of 100-130L/min, and growing a GaN barrier layer with the thickness of 10 nm;
Repeating the steps A-G, and periodically and sequentially carrying out the steps of In-doped pretreatment, inGaN well layer growth, ga 2O3 pre-growth, ga 2O3 layer growth, annealing treatment, gaN graded layer growth and GaN barrier layer growth, wherein the number of cycles is 2-12.
2. The method for epitaxial growth of LED according to claim 1, wherein the sapphire substrate is processed for 5-10min at 1000-1100 ℃ by introducing H 2 of 100-130L/min and maintaining the pressure of the reaction chamber at 100-300 mbar.
3. The method for epitaxial growth of LEDs according to claim 2, wherein the specific process of growing the low temperature GaN buffer layer is:
cooling to 500-600 ℃, maintaining the pressure of the reaction cavity at 300-600mbar, introducing NH 3 with the flow rate of 10000-20000sccm, TMGa with the flow rate of 50-100sccm and H 2 with the flow rate of 100-130L/min, and growing a low-temperature GaN buffer layer with the thickness of 20-40nm on the sapphire substrate;
Raising the temperature to 1000-1100 ℃, maintaining the pressure of the reaction cavity at 300-600mbar, introducing NH 3 with the flow rate of 30000-40000sccm and H 2 with the flow rate of 100-130L/min, preserving heat for 300-500s, and corroding the low-temperature GaN buffer layer into an irregular island shape.
4. The method for epitaxial growth of LEDs according to claim 1, wherein the specific process of growing undoped GaN layer is:
Raising the temperature to 1000-1200 ℃, keeping the pressure of the reaction cavity at 300-600mbar, introducing NH 3 with the flow rate of 30000-40000sccm, TMGa with the flow rate of 200-400sccm and H 2 with the flow rate of 100-130L/min, and continuously growing a 2-4 mu m undoped GaN layer.
5. The method for epitaxial growth of LEDs according to claim 1, wherein the specific process of growing the Si doped N-type GaN layer is:
Maintaining the pressure of the reaction cavity at 300-600mbar, maintaining the temperature at 1000-1200 ℃, introducing NH 3 with the flow rate of 30000-60000sccm, TMGa with the flow rate of 200-400sccm, H 2 with the flow rate of 100-130L/min and SiH 4 with the flow rate of 20-50sccm, and continuously growing N-type GaN doped with Si with the doping concentration of 3-4 μm, wherein the doping concentration of Si is 5E18-1E19atoms/cm 3.
6. The method for epitaxial growth of LEDs of claim 1, wherein said specific process of growing AlGaN electron blocking layer is:
And growing the AlGaN electron blocking layer under the conditions of the temperature of 900-950 ℃, the pressure of a reaction cavity of 200-400mbar, NH 3 with the concentration of 50000-70000sccm, TMGa with the concentration of 30-60sccm, H 2 with the concentration of 100-130L/min, TMAL with the concentration of 100-130sccm and Cp 2 Mg with the concentration of 1000-1300sccm, wherein the thickness of the AlGaN electron blocking layer is 40-60nm, and the doping concentration of Mg is 1E19-1E20atoms/cm 3.
7. The method for epitaxial growth of LEDs according to claim 1, wherein the specific process of growing Mg doped P-type GaN layer is:
Maintaining the pressure of the reaction cavity at 400-900mbar and the temperature at 950-1000 ℃, introducing NH 3 with the flow rate of 50000-70000sccm, TMGa with the flow rate of 20-100sccm, H 2 with the flow rate of 100-130L/min and Cp 2 Mg with the flow rate of 1000-3000sccm, and continuously growing a 50-200nm P-type GaN layer doped with Mg, wherein the doping concentration of Mg is 1E19-1E20atoms/cm 3.
8. The LED epitaxial growth method of claim 1, wherein the specific process of cooling down is:
Cooling to 650-680 deg.C, maintaining the temperature for 20-30min, closing the heating system, closing the gas supply system, and cooling with furnace.
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| JP2016051824A (en) * | 2014-08-29 | 2016-04-11 | 高知県公立大学法人 | Epitaxial growth method and growth device, and method of producing quantum well structure |
| CN111048636A (en) * | 2019-12-23 | 2020-04-21 | 江苏如高第三代半导体产业研究院有限公司 | Gallium oxide-based ultraviolet light-emitting diode and preparation method thereof |
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