CN112420883B - LED epitaxial growth method for improving luminous efficiency - Google Patents

LED epitaxial growth method for improving luminous efficiency Download PDF

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CN112420883B
CN112420883B CN202011292735.8A CN202011292735A CN112420883B CN 112420883 B CN112420883 B CN 112420883B CN 202011292735 A CN202011292735 A CN 202011292735A CN 112420883 B CN112420883 B CN 112420883B
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徐平
王杰
谢鹏杰
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Xiangneng Hualei Optoelectrical Co Ltd
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Abstract

The application discloses LED epitaxial growth method for improving luminous efficiency, which 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 the growing of the multi-quantum well layer sequentially comprises Mg-doped pretreatment, growing an InGaN well layer and growing In gradual change In x Mg 1‑x‑y N y The method comprises the steps of layer growing, mgAlN layer growing, gaN graded layer growing and GaN barrier layer growing. 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

LED epitaxial growth method for improving luminous efficiency
Technical Field
The invention belongs to the technical field of LEDs, and particularly relates to an LED epitaxial growth method for improving luminous efficiency.
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 foregoing, a new method for epitaxial growth of LEDs is urgently needed to solve the problems of low growth quality and low radiation recombination efficiency of quantum wells of the existing LEDs, so as to improve the light-emitting efficiency of 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 for improving the luminous efficiency sequentially comprises the following steps of: 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: mg-doped pretreatment, growth of InGaN well layer, growth of In graded In x Mg 1-x-y N y The method comprises the following specific steps of layer growth, mgAlN layer growth, gaN gradual change 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 ℃, and introducing NH 3 Cp and Cp 2 Mg, carrying out Mg-doped pretreatment for 25-35 seconds, and controlling the doping concentration of Mg to be 2E20 atoms/cm 3 Gradual decrease to 2E18atom/cm 3 ；
B. The pressure of the reaction cavity is kept unchanged, the temperature of the reaction cavity is increased to 900-950 ℃, and NH is introduced 3 TMGa and TMIn, and growing an InGaN well layer with the thickness of 3-5 nm;
C. maintaining the pressure of the reaction cavity unchanged, raising the temperature of the reaction cavity to 1000-1050 ℃, and introducing NH 3 、Cp 2 Mg, TMIn and N 2 Growing In with thickness of 8-12nm x Mg 1-x-y N y A layer, wherein x ranges from 0.05 to 0.20, y ranges from 0.02 to 0.15, and the atomic molar content of In is controlled to gradually increase from 8% to 20% during the growth process;
D. maintaining the pressure of the reaction cavity unchanged, reducing the temperature of the reaction cavity to 700-750 ℃, and introducing NH 3 、Cp 2 Mg, TMAL and N 2 Growing a MgAlN layer with the thickness of 10-15 nm;
E. raising the temperature of the reaction cavity to 850 ℃, raising the pressure of the reaction cavity to 300mbar, and introducing NH 3 、TMGa、N 2 SiH (SiH) 4 Growing a GaN gradient layer with the thickness of 5-8nm, and controlling the doping concentration of Si to be 1E22atom/cm in the growth process 3 Gradually reducing to 1E21atom/cm 3 Gradually reducing the temperature from 850 ℃ to 780 ℃ and gradually increasing the pressure of the reaction cavity from 300mbar to 450mbar;
F. controlling the temperature to 800 ℃, keeping the pressure of the reaction cavity to 300-400mbar, and introducing NH with the flow rate of 50000-70000sccm 3 TMGa 20-100sccm and N100-130L/min 2 Growing a GaN barrier layer of 10 nm;
repeating the steps A-F, periodically and sequentially carrying out Mg-doped pretreatment, inGaN well layer growth and In gradual change In growth x Mg 1-x-y N y The method comprises the steps of layer growth, mgAlN layer growth, gaN gradual change layer growth and GaN barrier layer growth, wherein the number of cycles is 3-10.
Preferably, the specific process of processing the substrate is as follows:
at 1000-1100 deg.c, H of 100-130L/min is introduced 2 The pressure of the reaction cavity is kept at 100-300mbar, and the sapphire substrate is processed for 5-10min.
Preferably, the specific process of growing the low-temperature GaN buffer layer is as follows:
cooling to 500-600deg.C, maintaining reaction chamber pressure at 300-600mbar, and introducing NH with flow rate of 10000-20000sccm 3 TMGa 50-100sccm and H100-130L/min 2 Growing a low-temperature GaN buffer layer with the thickness of 20-40nm on a sapphire substrate;
raising the temperature to 1000-1100 ℃, keeping the pressure of the reaction cavity at 300-600mbar, and introducing NH with the flow rate of 30000-40000sccm 3 H of 100-130L/min 2 Thermal insulation 300-And (500 s) etching 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, and introducing NH with the flow rate of 30000-40000sccm 3 TMGa 200-400sccm and H100-130L/min 2 And continuously growing an undoped GaN layer with the thickness of 2-4 mu m.
Preferably, the specific process of growing the Si-doped N-type GaN layer is as follows:
maintaining the pressure of the reaction cavity at 300-600mbar, maintaining the temperature at 1000-1200deg.C, and introducing NH with flow rate of 30000-60000sccm 3 200-400sccm TMGa, 100-130L/min H 2 SiH of 20-50sccm 4 Continuously growing N-type GaN doped with Si with the thickness of 3m-4 mu m, wherein the doping concentration of Si is 5E18-1E19atoms/cm 3 。
Preferably, the specific process of growing the AlGaN electron blocking layer is as follows:
introducing NH of 50000-70000sccm at 900-950 deg.C and reaction chamber pressure of 200-400mbar 3 30-60sccm TMGa, 100-130L/min H 2 100-130sccm TMAL, 1000-1300sccm Cp 2 Growing the AlGaN electron blocking layer under the condition of Mg, wherein the thickness of the AlGaN layer is 40-60nm, and the doping concentration of Mg is 1E19-1E20atoms/cm 3 。
Preferably, the specific process of growing the Mg-doped P-type GaN layer is as follows:
maintaining the pressure of the reaction cavity at 400-900mbar and the temperature at 950-1000 ℃, and introducing NH with the flow rate of 50000-70000sccm 3 TMGa 20-100sccm, H100-130L/min 2 Cp of 1000-3000sccm 2 Mg, continuously growing a 50-200nm Mg doped P-type GaN layer, wherein the Mg doping concentration is 1E19 3 -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 for improving the luminous efficiency achieves the following effects:
1. in the growth process of the multi-quantum well layer, mg doping pretreatment is firstly carried out, the doping concentration of Mg is controlled to change regularly, the crystallization quality of an InGaN well layer is improved, the dislocation density is reduced, the hole concentration and the mobility of a quantum well region are improved, more hole-electron pairs are provided for a light-emitting active region of an LED device, the carrier recombination probability is improved, the brightness is improved, and the photoelectric performance of the LED device is improved.
2. The multi-quantum well layer of the invention regenerates In gradual change In after the InGaN well layer is grown x Mg 1-x-y N y The layer can increase the number of the quasi quantum dots of the light-emitting layer, improve the overlapping integration of electron and hole wave functions and improve the recombination efficiency of electrons and holes. The molar content of In atoms is uniformly increased In the growth process, so that fluctuation of In component distribution In the multi-quantum well layer is regulated, the surface morphology of the material can be changed, and the surface mobility of In atoms is improved; since the surface mobility of In atoms is improved, the optical quality can be changed, thereby improving the luminous efficiency of the LED.
3. According to the invention, the MgAlN layer is introduced into the multi-quantum well layer, so that effective potential barrier difference can be formed near the quantum well, and the potential barrier difference can inhibit holes in the quantum well from overflowing the quantum well, so that the hole concentration in the quantum well can be effectively improved, the recombination probability of electrons and holes is further improved, and the luminous efficiency of the LED is improved.
4. The multiple quantum well layer grows the GaN gradual change layer before growing the GaN barrier layer, and the distribution central axes of holes and electrons in the multiple quantum well are overlapped by uniformly changing the temperature, the pressure and the doping concentration of Si, so that the efficiency of electron-to-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, in gradual change In x Mg 1-x-y N y Layer, 53, mgAlN layer, 54, gaN graded layer, 55, 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 the preferred embodiment for carrying out the present application, but is not intended to limit the scope of the present application in general, for the purpose of illustrating the general principles of the present application. The scope of the present 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 is described in further detail below with reference to the drawings, but is not intended to be limiting.
Example 1
The embodiment adopts the LED epitaxial growth method for improving the luminous efficiency, adopts MOCVD to grow the GaN-based LED epitaxial wafer, and adopts high-purity H 2 Or high purity N 2 Or high purity H 2 And high purity N 2 High purity NH using the mixed gas of (2) as carrier gas 3 As N source, trimethyl gallium (TMGa) as gallium source, trimethyl indium (TMIn) as indium source, and Silane (SiH) as N-type dopant 4 ) Trimethylaluminum (TMAL) as aluminum source, the P-type dopant is magnesium dicyclopentadiene (CP) 2 Mg) at a reaction pressure of between 70mbar and 900 mbar. The specific growth mode is as follows (see fig. 1 for epitaxial structure):
an LED epitaxial growth method for improving luminous efficiency 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, the liquid crystal display device comprises a liquid crystal display device,
step 1: the sapphire substrate 1 is processed.
Specifically, the step 1 is further that:
at 1000-1100 deg.C, the pressure of reaction cavity is 100-300mbar, H is introduced into the reaction cavity at 100-130L/min 2 The sapphire substrate is processed for 5 to 10 minutes.
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:
introducing 10000-20000sccm NH at 500-600deg.C and reaction chamber pressure of 300-600mbar 3 50-100sccm TMGa, 100-130L/min H 2 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;
introducing NH of 30000-40000sccm at 1000-1100deg.C and reaction chamber pressure of 300-600mbar 3 H of 100-130L/min 2 The temperature is kept for 300-500s, and the irregular island is formed on the low-temperature GaN buffer layer 2.
Step 3: the undoped GaN layer 3 is grown.
Specifically, the step 3 is further:
introducing NH of 30000-40000sccm at 1000-1200deg.C and reaction chamber pressure of 300-600mbar 3 200-400sccm TMGa, 100-130L/min H 2 The undoped GaN layer 3 is grown; the undoped GaN layer 3 has a thickness of 2-4 μm.
Step 4: a Si doped N-type GaN layer 4 is grown.
Specifically, the step 4 is further:
maintaining the pressure of the reaction cavity at 300-600mbar, maintaining the temperature at 1000-1200deg.C, and introducing NH with flow rate of 30000-60000sccm 3 200-400sccm TMGa, 100-130L/min H 2 SiH of 20-50sccm 4 Continuously growing an N-type GaN layer 4 doped with Si with the thickness of 3-4 mu m, wherein the doping concentration of Si is 5E18-5E19atoms/cm 3 。
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 ℃, and introducing NH 3 Cp and Cp 2 Mg, carrying out Mg-doped pretreatment for 25-35 seconds, and controlling the doping concentration of Mg to be 2E20 atoms/cm 3 Gradual decrease to 2E18atom/cm 3 ；
B. The pressure of the reaction cavity is kept unchanged, the temperature of the reaction cavity is increased to 900-950 ℃, and NH is introduced 3 TMGa and TMIn, and an InGaN well layer 51 having a thickness of 3 to 5nm is grown;
C. maintaining the pressure of the reaction cavity unchanged, raising the temperature of the reaction cavity to 1000-1050 ℃, and introducing NH 3 、Cp 2 Mg, TMIn and N 2 Growing In with thickness of 8-12nm x Mg 1-x-y N y Layer 52, where x ranges from 0.05 to 0.20 and y ranges from 0.02 to 0.15, controlling the In atomic molar content to gradually increase from 8% to 20% during growth;
D. maintaining the pressure of the reaction cavity unchanged, reducing the temperature of the reaction cavity to 700-750 ℃, and introducing NH 3 、Cp 2 Mg, TMAL and N 2 Growing a MgAlN layer 53 with the thickness of 10-15 nm;
E. raising the temperature of the reaction cavity to 850 ℃, raising the pressure of the reaction cavity to 300mbar, and introducing NH 3 、TMGa、N 2 SiH (SiH) 4 Growing a GaN gradient layer 54 with the thickness of 5-8nm, and controlling the doping concentration of Si to be 1E22atom/cm during the growth process 3 Gradually reducing to 1E21atom/cm 3 Gradually reducing the temperature from 850 ℃ to 780 ℃ and gradually increasing the pressure of the reaction cavity from 300mbar to 450mbar;
F. controlling the temperature to 800 ℃, keeping the pressure of the reaction cavity to 300-400mbar, and introducing NH with the flow rate of 50000-70000sccm 3 TMGa 20-100sccm and N100-130L/min 2 Growing a GaN barrier layer 55 of 10 nm;
repeating the steps A-F, periodically and sequentially carrying out Mg-doped pretreatment, inGaN well layer 51 growth and In gradual change In growth x Mg 1-x-y N y The steps of the layer 52, the MgAlN layer 53, the GaN graded layer 54 and the GaN barrier layer 55 are carried out, and the number of cycles is 3-10.
Step 6: an AlGaN electron blocking layer 6 is grown.
Specifically, the step 6 is further:
introducing NH of 50000-70000sccm at 900-950 deg.C and reaction chamber pressure of 200-400mbar 3 30-60sccm TMGa, 100-130L/min H 2 100-130sccm TMAL, 1000-1300sccm Cp 2 Growing the AlGaN electron blocking layer 6 under the condition of Mg, wherein the thickness of the AlGaN 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:
introducing NH of 50000-70000sccm at 950-1000deg.C and reaction chamber pressure of 400-900mbar 3 TMGa 20-100sccm, H100-130L/min 2 Cp of 1000-3000sccm 2 Under the condition of Mg, growing a Mg-doped P-type GaN layer 7 with the thickness of 50-200nm and the Mg doping concentration of 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: at 1000-1100 deg.C, the pressure of reaction cavity is 100-300mbar, H is introduced into the reaction cavity at 100-130L/min 2 The sapphire substrate is processed for 5 to 10 minutes.
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:
introducing 10000-20000sccm NH at 500-600deg.C and reaction chamber pressure of 300-600mbar 3 50-100sccm TMGa, 100-130L/min H 2 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;
introducing NH of 30000-40000sccm at 1000-1100deg.C and reaction chamber pressure of 300-600mbar 3 H of 100-130L/min 2 The temperature is kept for 300-500s, and the irregular island is formed on the low-temperature GaN buffer layer 2.
Step 3: the undoped GaN layer 3 is grown.
Specifically, the step 3 is further:
introducing NH of 30000-40000sccm at 1000-1200deg.C and reaction chamber pressure of 300-600mbar 3 200-400sccm TMGa, 100-130L/min H 2 The undoped GaN layer is grown; the undoped GaN layer 3 has a thickness of 2-4 μm.
Step 4: a Si doped N-type GaN layer 4 is grown.
Specifically, the step 4 is further:
introducing NH of 30000-60000sccm at 1000-1200deg.C and reaction chamber pressure of 300-600mbar 3 200-400sccm TMGa, 100-130L/min H 2 、20-50sccmSiH of (2) 4 A Si-doped N-type GaN layer 4 is grown, the thickness of the N-type GaN layer is 3-4 mu m, and the Si doping concentration is 5E18-1E19atoms/cm 3 。
Step 5: an InGaN/GaN multi-quantum hydrazine layer 5 is grown.
Specifically, the growing multi-quantum hydrazine layer 5 is further:
maintaining the pressure of the reaction cavity at 300-400mbar and the temperature at 720 ℃, and introducing NH with the flow rate of 50000-70000sccm 3 20-40sccm TMGa, 10000-15000sccm TMIn and 100-130L/min N 2 An InGaN well layer 51 doped with In and having a thickness of 3nm is grown;
raising the temperature to 800 ℃, keeping the pressure of the reaction cavity at 300-400mbar, and introducing NH with the flow rate of 50000-70000sccm 3 TMGa 20-100sccm and N100-130L/min 2 Growing a GaN barrier layer 55 of 10 nm;
and repeatedly and alternately growing the InGaN well layer 51 and the GaN barrier layer 55 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 55 is 7-13.
Step 6: an AlGaN electron blocking layer 6 is grown.
Specifically, the step 6 is further:
introducing NH of 50000-70000sccm at 900-950 deg.C and reaction chamber pressure of 200-400mbar 3 30-60sccm TMGa, 100-130L/min H 2 100-130sccm TMAL, 1000-1300sccm Cp 2 Growing the AlGaN electron blocking layer 6 under the condition of Mg, wherein the thickness of the AlGaN electron blocking 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:
introducing NH of 50000-70000sccm at 950-1000deg.C and reaction chamber pressure of 400-900mbar 3 TMGa 20-100sccm, H100-130L/min 2 Cp of 1000-3000sccm 2 Under the condition of Mg, growing a Mg-doped P-type GaN layer 7 with the thickness of 50-200nm and the Mg doping concentration of 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, and sample 1 and sample 2 were coated with an ITO layer of about 150nm under the same pre-process conditions, with Cr/Pt/Au electrodes of about 1500nm under the same conditions, and with a protective layer of SiO under the same conditions 2 About 100nm, then the samples were ground and cut under the same conditions into 635 μm (25 mil) chip particles, after which sample 1 and sample 2 were each picked 1000 dies in the same location and packaged under the same packaging process into white LEDs. 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
Figure BDA0002784405420000101
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 for improving the luminous efficiency achieves the following effects:
1. in the growth process of the multi-quantum well layer, mg doping pretreatment is firstly carried out, the doping concentration of Mg is controlled to change regularly, the crystallization quality of an InGaN well layer is improved, the dislocation density is reduced, the hole concentration and the mobility of a quantum well region are improved, more hole-electron pairs are provided for a light-emitting active region of an LED device, the carrier recombination probability is improved, the brightness is improved, and the photoelectric performance of the LED device is improved.
2. The multi-quantum well layer of the invention regenerates In gradual change In after the InGaN well layer is grown x Mg 1-x-y N y The layer can increase the number of the quasi quantum dots of the light-emitting layer, improve the overlapping integration of electron and hole wave functions and improve the recombination efficiency of electrons and holes. The molar content of In atoms is uniformly increased In the growth process, so that fluctuation of In component distribution In the multi-quantum well layer is regulated, the surface morphology of the material can be changed, and the surface mobility of In atoms is improved; since the surface mobility of In atoms is improved, the optical quality can be changed, thereby improving the luminous efficiency of the LED.
3. According to the invention, the MgAlN layer is introduced into the multi-quantum well layer, so that effective potential barrier difference can be formed near the quantum well, and the potential barrier difference can inhibit holes in the quantum well from overflowing the quantum well, so that the hole concentration in the quantum well can be effectively improved, the recombination probability of electrons and holes is further improved, and the luminous efficiency of the LED is improved.
4. 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 been described in detail in the embodiments of the present application, the description of the structures and the corresponding parts of the methods related in the embodiments is omitted, and is not repeated here. 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 this application is not limited to the forms disclosed herein, but is not to be construed as an exclusive use of other embodiments, and is capable of many other combinations, modifications and environments, and adaptations within the scope of the teachings described herein, through the foregoing teachings or through the knowledge or skills of the relevant art. And that modifications and variations which do not depart from the spirit and scope of the present invention are intended to be within the scope of the appended claims.

Claims (8)

1. An LED epitaxial growth method for improving luminous efficiency 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: mg-doped pretreatment, growth of InGaN well layer, growth of In graded In x Mg 1-x-y N y The method comprises the following specific steps of layer growth, mgAlN layer growth, gaN gradual change 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 ℃, and introducing NH 3 Cp and Cp 2 Mg, carrying out Mg-doped pretreatment for 25-35 seconds, and controlling the doping concentration of Mg to be 2E20 atoms/cm 3 Gradual decrease to 2E18atom/cm 3 ；
B. The pressure of the reaction cavity is kept unchanged, the temperature of the reaction cavity is increased to 900-950 ℃, and NH is introduced 3 TMGa and TMIn, and growing an InGaN well layer with the thickness of 3-5 nm;
C. maintaining the pressure of the reaction cavity unchanged, raising the temperature of the reaction cavity to 1000-1050 ℃, and introducing NH 3 、Cp 2 Mg, TMIn and N 2 Growing In with thickness of 8-12nm x Mg 1-x-y N y A layer, wherein x ranges from 0.05 to 0.20, y ranges from 0.02 to 0.15, and the atomic molar content of In is controlled to gradually increase from 8% to 20% during the growth process;
D. maintaining the pressure of the reaction cavity unchanged, reducing the temperature of the reaction cavity to 700-750 ℃, and introducing NH 3 、Cp 2 Mg, TMAL and N 2 Growing a MgAlN layer with the thickness of 10-15 nm;
E. raising the temperature of the reaction cavity to 850 ℃, raising the pressure of the reaction cavity to 300mbar, and introducing NH 3 、TMGa、N 2 SiH (SiH) 4 Growing a GaN gradient layer with the thickness of 5-8nm, and controlling the doping concentration of Si to be 1E22atom/cm in the growth process 3 Gradually reducing to 1E21atom/cm 3 Gradually reducing the temperature from 850 ℃ to 780 ℃ and gradually increasing the pressure of the reaction cavity from 300mbar to 450mbar;
F. the temperature was controlled at 800 c,maintaining the pressure of the reaction cavity at 300-400mbar, and introducing NH with the flow rate of 50000-70000sccm 3 TMGa 20-100sccm and N100-130L/min 2 Growing a GaN barrier layer of 10 nm;
repeating the steps A-F, periodically and sequentially carrying out Mg-doped pretreatment, inGaN well layer growth and In gradual change In growth x Mg 1-x- y N y The method comprises the steps of layer growth, mgAlN layer growth, gaN gradual change layer growth and GaN barrier layer growth, wherein the number of cycles is 3-10.
2. The method for epitaxial growth of LED with improved luminous efficiency as claimed in claim 1, wherein H of 100-130L/min is introduced at 1000-1100deg.C 2 The pressure of the reaction cavity is kept at 100-300mbar, and the sapphire substrate is processed for 5-10min.
3. The method for epitaxial growth of LED for improving luminous efficiency of claim 2, wherein the specific process of growing the low temperature GaN buffer layer is as follows:
cooling to 500-600deg.C, maintaining reaction chamber pressure at 300-600mbar, and introducing NH with flow rate of 10000-20000sccm 3 TMGa 50-100sccm and H100-130L/min 2 Growing a low-temperature GaN buffer layer with the thickness of 20-40nm on a sapphire substrate;
raising the temperature to 1000-1100 ℃, keeping the pressure of the reaction cavity at 300-600mbar, and introducing NH with the flow rate of 30000-40000sccm 3 H of 100-130L/min 2 Preserving the temperature for 300-500s, and corroding the low-temperature GaN buffer layer into an irregular island shape.
4. The method for epitaxial growth of LED for improving luminous efficiency of claim 1, wherein the specific process of growing undoped GaN layer is as follows:
raising the temperature to 1000-1200 ℃, keeping the pressure of the reaction cavity at 300-600mbar, and introducing NH with the flow rate of 30000-40000sccm 3 TMGa 200-400sccm and H100-130L/min 2 And continuously growing an undoped GaN layer with the thickness of 2-4 mu m.
5. The method for epitaxially growing an LED with improved luminous efficiency according to claim 1, wherein the specific process of growing the Si-doped N-type GaN layer is as follows:
maintaining the pressure of the reaction cavity at 300-600mbar, maintaining the temperature at 1000-1200deg.C, and introducing NH with flow rate of 30000-60000sccm 3 200-400sccm TMGa, 100-130L/min H 2 SiH of 20-50sccm 4 Continuously growing N-type GaN doped with Si with the thickness of 3-4 mu m, wherein the doping concentration of Si is 5E18-1E19atoms/cm 3 。
6. The method for epitaxial growth of LED for improving luminous efficiency of claim 1, wherein the specific process of growing AlGaN electron blocking layer is:
introducing NH of 50000-70000sccm at 900-950 deg.C and reaction chamber pressure of 200-400mbar 3 30-60sccm TMGa, 100-130L/min H 2 100-130sccm TMAL, 1000-1300sccm Cp 2 Growing the AlGaN electron blocking layer under the condition of Mg, wherein the thickness of the AlGaN layer is 40-60nm, and the doping concentration of Mg is 1E19-1E20atoms/cm 3 。
7. The method for epitaxially growing an LED with improved luminous efficiency according to claim 1, wherein the specific process of growing the Mg doped P-type GaN layer is as follows:
maintaining the pressure of the reaction cavity at 400-900mbar and the temperature at 950-1000 ℃, and introducing NH with the flow rate of 50000-70000sccm 3 TMGa 20-100sccm, H100-130L/min 2 Cp of 1000-3000sccm 2 Mg, continuously growing a 50-200nm Mg-doped P-type GaN layer, wherein the doping concentration of Mg is 1E19-1E20atoms/cm 3 。
8. The method for LED epitaxial growth to improve luminous efficiency according to claim 1, wherein the specific process of cooling 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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