CN111725371A - LED epitaxial bottom layer structure and growth method thereof - Google Patents
LED epitaxial bottom layer structure and growth method thereof Download PDFInfo
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- CN111725371A CN111725371A CN201910216879.6A CN201910216879A CN111725371A CN 111725371 A CN111725371 A CN 111725371A CN 201910216879 A CN201910216879 A CN 201910216879A CN 111725371 A CN111725371 A CN 111725371A
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- H—ELECTRICITY
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- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/26—Materials of the light emitting region
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- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
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- H01L33/0062—Processes for devices with an active region comprising only III-V compounds
- H01L33/0075—Processes for devices with an active region comprising only III-V compounds comprising nitride compounds
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
- H01L33/14—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
Abstract
The invention relates to an LED epitaxial bottom layer structure and a growth method thereof, belonging to the technical field of LED epitaxial growth. The structure comprises a sapphire substrate, an AlGaN/AlN nucleating layer, a non-doped GaN layer, an N-type GaN layer, a multi-quantum well layer, a p-type AlGaN layer and a p-type GaN layer from bottom to top; the AlGaN/AlN nucleating layer is formed by alternately growing the ALGaN buffer layer and the high-temperature ALN layer for 3-10 periods. The invention has the advantages of influencing the lattice mismatch between the substrate and the epitaxy, changing the stress distribution of the epitaxial wafer so as to change the warping degree in the growth process, improving the crystallization quality of the GaN film grown under the high-temperature condition and improving the uniformity, improving the structural quality of the whole LED epitaxial layer, increasing the radiative recombination probability of current carriers by reducing the structural defects so as to improve the brightness, lowering the production cost, improving the growth quality and finally improving the luminous efficiency of the GaN-based LED device.
Description
Technical Field
The invention relates to an LED epitaxial bottom layer structure and a growth method thereof, belonging to the technical field of LED epitaxial growth.
Background
A Light Emitting Diode (LED) is a semiconductor solid Light Emitting device that directly converts electricity into Light using a semiconductor PN junction as a Light Emitting material. When a forward voltage is applied to two ends of a PN junction of a semiconductor body, minority carriers injected into the PN junction are recombined, excess energy is released to cause photon emission, and light with the colors of red, orange, yellow, green, cyan, blue and purple is directly emitted. Among them, the III-V group compound semiconductor represented by gallium nitride (GaN) has a great potential for application in the field of photoelectrons such as high-brightness blue light emitting diodes and blue lasers due to its characteristics of wide band gap, high luminous efficiency, high electron saturation drift velocity, stable chemical properties, etc., and has attracted much attention.
Currently, epitaxial growth of GaN-based semiconductor materials is mainly achieved using organic chemical metal vapor deposition (MOCVD). The method comprises the following steps: with high purity H2Or N2Or hydrogen-nitrogen mixed gas is used as carrier gas, and the sapphire substrate is processed at the high temperature of 1000-1100 ℃ for 5-20 minutes under the pressure of 760-780 Torr; reducing the temperature to 480-550 ℃, and growing a low-temperature buffer gallium nitride layer with the thickness of 10-50 nm on the sapphire substrate; raising the temperature to 1000-1100 ℃, and continuously growing 1-2.5 mu m of undoped gallium nitride (uGaN) on the low-temperature buffer gallium nitride layer; keeping the temperature, and continuously growing an n-type Si-doped gallium nitride layer of 2-4 mu m on the undoped gallium nitride layer; raising the temperature to 700-800 ℃, growing an indium-doped gallium nitride well layer on the n-type Si-doped gallium nitride layer, raising the temperature to 800-1000 ℃ to grow an undoped gallium nitride barrier layer on the indium-doped gallium nitride well layer, forming a group of quantum well barriers by the well layer and the barrier layer, and repeatedly growing one or more groups of quantum well barriers to form an active layer; after the growth of the active layer is finished, raising the temperature to 950-1050 ℃ and continuously growing a 20-80 nm p-type aluminum gallium nitride layer; reducing the temperature to 900-1000 ℃, and continuously growing a magnesium-doped p-type gallium nitride layer with the thickness of 0.1-0.5 mu m on the p-type aluminum gallium nitride layer; reducing the temperature to 600-700 ℃, and growing a low-temperature magnesium-doped indium gallium nitride layer with the thickness of 5-10 nm on the magnesium-doped p-type gallium nitride layer; reducing the temperature by 600-750 ℃, and activating the p-type aluminum gallium nitrogen layer in a nitrogen atmosphere for 10-30 minutes.
The growth of GaN epitaxy by using MOCVD equipment generally requires that a sapphire substrate is placed in a reaction chamber for reaction. Due to the lattice mismatch between sapphire and GaN, dislocations may be generated during growth to affect the crystalline quality. In order to minimize the influence of these dislocations, it is generally necessary to grow a GaN buffer layer on sapphire and then grow a GaN single crystal when growing a high-purity GaN single crystal. The composition and growth conditions of the buffer layer play a crucial role in the crystalline quality of the GaN crystal. When the MOCVD machine station grows epitaxy, particularly a patterned substrate is used, the epitaxial wafer is warped due to lattice mismatch between the substrate and the epitaxy and stress generated by thermal deformation difference, so that the center and the edge of the epitaxy are not uniform when an epitaxial structure is grown, and finally the uniformity is caused, and the luminous intensity of the epitaxial wafer is greatly reduced. The epitaxial buffer layer is a connecting layer between the sapphire substrate and the GaN epitaxy, the growth condition can affect the lattice mismatch between the substrate and the epitaxy, the stress distribution of an epitaxial wafer is changed, the warping degree in the growth process is changed, the crystallization quality of a GaN film grown under a high-temperature condition is improved, the uniformity is improved, the structural quality of the whole LED epitaxy layer is higher, the reduction of structural defects enables the radiative recombination probability of carriers to be increased, the brightness is improved, the production cost is low, the growth quality is improved, and the luminous efficiency of the GaN-based LED device is finally improved.
The invention content is as follows:
the invention provides an LED epitaxial bottom layer structure for improving GaN crystal quality and a growth method thereof, aiming at the problems of the existing GaN-based LED epitaxial growth technology.
The invention adopts the following technical scheme:
an LED epitaxial bottom layer structure comprises a sapphire substrate, an AlGaN/AlN nucleating layer, an undoped GaN layer, an N-type GaN layer, a multi-quantum well layer, a p-type AlGaN layer and a p-type GaN layer from bottom to top;
the AlGaN/AlN nucleating layer is formed by alternately growing an ALGaN buffer layer and a high-temperature ALN layer for 3-10 periods.
A growth method of the LED epitaxial bottom layer structure comprises the following steps:
(1) growing an ALGaN buffer layer on a sapphire substrate, namely growing a low-temperature GaN buffer layer with the thickness of 5nm-20nm in a reaction chamber of an MOCVD growth furnace at the temperature of 500-600 ℃;
(2) growing an ALN layer on the ALGaN buffer layer at the high temperature of 950-1050 ℃;
(3) alternately growing the ALGaN buffer layer and the ALN layer for 3-10 cycles to obtain an AlGaN/AlN nucleating layer;
(4) heating the MOCVD growth furnace to 1150 ℃ to grow the non-doped GaN layer with the thickness of 2.5 mu m;
(5) growing an n-type GaN layer with the thickness of 3 mu m at 1150 ℃;
(6) growing a 12-period multi-quantum well layer;
(7) heating an MOCVD growth furnace to 1000 ℃ to grow a p-type AlGaN layer with the thickness of 60 nm;
(8) cooling the MOCVD growth furnace to 980 ℃ to grow a p-type GaN layer with the thickness of 160 nm;
(9) and cooling the MOCVD growth furnace to 950-980 ℃ to grow the highly-doped p-type GaN electrode contact layer with the thickness of 25nm, cooling to room temperature (generally 25 +/-5 ℃), and finishing the growth.
Preferably, in the step (2), the growing time for growing the ALN layer is 1-30 minutes, the Al flow rate is 10-60 sccm, and more preferably, the Al flow rate is 10-60 sccm.
Preferably, the Al flow rate is 30 sccm.
Preferably, in step (2), the ALN layer has a thickness of 1nm to 10nm in length.
Preferably, in the step (3), the ALGaN buffer layer and the ALN layer are alternately grown for 5-10 cycles to obtain an AlGaN/AlN nucleation layer;
preferably, in the step (6), in the multiple quantum well layer, the thickness of the GaN barrier layer is 13nm, the growth temperature is 850 ℃, the thickness of the InGaN well layer is 2nm, and the growth temperature is 760 ℃.
The invention has the beneficial effects that:
according to the invention, the AlGaN buffer layer grown at low temperature is utilized, the AlN layer is grown at high temperature and alternately grown, and then the AlGaN/Al nucleating layer is formed, so that the growth method can affect the lattice mismatch between the substrate and the epitaxy, effectively release the stress between the sapphire substrate and the GaN, change the stress distribution of the epitaxial wafer so as to change the warping degree in the growth process, improve the crystallization quality of the GaN film grown under the high-temperature condition and improve the uniformity, so that the structural quality of the whole LED epitaxial layer is higher, the reduction of structural defects increases the radiative recombination probability of carriers so as to improve the brightness, reduce the production cost, improve the growth quality, and finally improve the luminous efficiency of the GaN-based LED device.
Description of the drawings:
FIG. 1 is a schematic diagram of an LED epitaxial underlayer structure of the present invention;
the solar cell comprises a sapphire substrate, 2, an AlGaN/AlN nucleating layer, 2-a, an ALGaN buffer layer, 2-b, a high-temperature ALN layer, 4, N-type GaN, 5, a multi-quantum well layer, 6, a p-type AlGaN layer, 7 and a p-type GaN layer.
The specific implementation mode is as follows:
in order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific examples, but not limited thereto, and the present invention is not described in detail and is in accordance with the conventional techniques in the art.
Example 1:
an LED epitaxial bottom layer structure is shown in figure 1 and comprises a sapphire substrate 1, an AlGaN/AlN nucleating layer 2, an undoped GaN layer (not shown in the figure), an N-type GaN layer 4, a multi-quantum well layer 5, a p-type AlGaN layer 6 and a p-type GaN layer 7 from bottom to top;
the AlGaN/AlN nucleating layer 2 is formed by alternately growing an ALGaN buffer layer 2-a and a high-temperature ALN layer 2-b for 3-10 periods.
Example 2:
a growth method of an LED epitaxial bottom layer structure comprises the following steps:
(1) growing an ALGaN buffer layer 2-a on the sapphire substrate 1, namely growing a low-temperature GaN buffer layer with the thickness of 5nm in a reaction chamber of an MOCVD growth furnace at 550 ℃;
(2) growing an ALN layer 2-b on the ALGaN buffer layer 2-a at the high temperature of 950-;
(3) alternately growing the ALGaN buffer layer 2-a and the ALN layer 2-b for 6 cycles to obtain an AlGaN/AlN nucleating layer 2;
(4) heating the MOCVD growth furnace to 1150 ℃ to grow the non-doped GaN layer with the thickness of 2.5 mu m;
(5) growing an n-type GaN layer 4 with a thickness of 3 μm at 1150 ℃;
(6) growing a 12-period MQW layer 5;
(7) heating the MOCVD growth furnace to 1000 ℃ to grow a p-type AlGaN layer 6 with the thickness of 60 nm;
(8) cooling the MOCVD growth furnace to 980 ℃ to grow a p-type GaN layer 7 with the thickness of 160 nm;
(9) and cooling the MOCVD growth furnace to 950-980 ℃ to grow the highly-doped p-type GaN electrode contact layer with the thickness of 25nm, cooling to room temperature, and finishing the growth.
Example 3:
a method for growing an epitaxial bottom layer structure of an LED, as shown in example 2, except that in the step (2), the growth time is 1 minute, and the Al flow rate is 30 sccm.
Example 4:
a method for growing an epitaxial bottom layer structure of an LED, as shown in example 2, except that the ALN layer in step (2) has a thickness of 5 nm.
Example 5:
a method for growing an epitaxial bottom layer structure of an LED, as shown in example 2, except that in a multiple quantum well layer, a GaN barrier layer has a thickness of 13nm, a growth temperature of 850 ℃, an InGaN well layer has a thickness of 2nm, and a growth temperature of 760 ℃.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (7)
1. An LED epitaxial bottom layer structure is characterized by comprising a sapphire substrate, an AlGaN/AlN nucleating layer, an undoped GaN layer, an N-type GaN layer, a multi-quantum well layer, a p-type AlGaN layer and a p-type GaN layer from bottom to top;
the AlGaN/AlN nucleating layer is formed by alternately growing an ALGaN buffer layer and a high-temperature ALN layer for 3-10 periods.
2. A method of growing an LED epitaxial underlayer structure as claimed in claim 1, comprising the steps of:
(1) growing an ALGaN buffer layer on a sapphire substrate, namely growing a low-temperature GaN buffer layer with the thickness of 5nm-20nm in a reaction chamber of an MOCVD growth furnace at the temperature of 500-600 ℃;
(2) growing an ALN layer on the ALGaN buffer layer at the high temperature of 950-1050 ℃;
(3) alternately growing the ALGaN buffer layer and the ALN layer for 3-10 cycles to obtain an AlGaN/AlN nucleating layer;
(4) heating the MOCVD growth furnace to 1150 ℃ to grow the non-doped GaN layer with the thickness of 2.5 mu m;
(5) growing an n-type GaN layer with the thickness of 3 mu m at 1150 ℃;
(6) growing a 12-period multi-quantum well layer;
(7) heating an MOCVD growth furnace to 1000 ℃ to grow a p-type AlGaN layer with the thickness of 60 nm;
(8) cooling the MOCVD growth furnace to 980 ℃ to grow a p-type GaN layer with the thickness of 160 nm;
(9) and cooling the MOCVD growth furnace to 950 ℃ to grow the highly-doped p-type GaN electrode contact layer with the thickness of 25nm, cooling to room temperature, and finishing the growth.
3. The method for growing an LED epitaxial underlayer structure as claimed in claim 2, wherein in the step (2), the growth time for growing the ALN layer is 1 to 30 minutes, and the Al flow rate is 10 to 60 sccm.
4. The method of claim 3, wherein the Al flux is 30 sccm.
5. The growth method of the LED epitaxial underlayer structure as claimed in claim 2, wherein in the step (2), the thickness of the ALN layer is 1nm to 10nm in length.
6. The growth method of the LED epitaxial underlayer structure as claimed in claim 2, wherein in the step (3), the ALGaN buffer layer and the ALN layer are alternately grown for 3-10 cycles to obtain the AlGaN/AlN nucleation layer.
7. The growth method of the LED epitaxial underlayer structure as claimed in claim 2, wherein in the step (6), in the multiple quantum well layer, the thickness of the GaN barrier layer is 13nm, the growth temperature is 850 ℃, the thickness of the InGaN well layer is 2nm, and the growth temperature is 760 ℃.
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| CN113725330A (en) * | 2021-08-10 | 2021-11-30 | 广州市众拓光电科技有限公司 | Silicon-based LED epitaxial structure and preparation method and application thereof |
| WO2023231566A1 (en) * | 2022-05-30 | 2023-12-07 | 湖南三安半导体有限责任公司 | Semiconductor epitaxial structure and preparation method therefor, and semiconductor device |
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