A UV LED epitaxial structure and its growth method
By growing multiple AlN layers in the epitaxial structure of UV LEDs, the problem of low luminous efficiency of UV LEDs has been solved, and the crystal quality and luminous efficiency have been significantly improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUANGZHOU ZHONGTUO PHOTOELECTRIC TECH CO LTD
- Filing Date
- 2022-03-09
- Publication Date
- 2026-06-30
AI Technical Summary
The low luminous efficiency of UV LEDs limits their further application.
A growth method is adopted to sequentially grow a buffer layer, an unintentionally doped layer, an n-type doped layer, a multi-quantum-well light-emitting layer, an EBL layer, and a p-type AlGaN layer on a substrate. Specifically, the growth temperature and gas flow rate are controlled to form a multilayer AlN layer to improve crystal quality.
This improves the crystal quality of UV LED epitaxial wafers, reduces nonradiative recombination caused by defects, increases the recombination probability of electrons and holes, and greatly improves luminous efficiency.
Smart Images
Figure CN114744083B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor materials technology, specifically relating to a UV LED epitaxial structure and its growth method. Background Technology
[0002] With the continuous development of LED technology, the emission wavelength of LEDs has expanded from the visible light band to the ultraviolet band. The ultraviolet band has a wavelength of 100–400 nm. Based on different wavelengths, ultraviolet light is generally divided into three bands: UVA (400–315 nm), UVB (315–280 nm), and UVC (280–100 nm). UVA is mainly used for ultraviolet curing and UV inkjet printing, UVB is primarily used in medical applications, and UVC is used for sterilization and disinfection. As a new type of ultraviolet light source, UV LEDs have advantages such as low energy consumption, small size, good integration, long lifespan, and environmental friendliness, making them one of the most promising fields and industries in the current III-nitride semiconductor industry. Although UV LEDs have broad application prospects, their luminous efficiency is lower than that of blue light, which limits their further application. Summary of the Invention
[0003] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a method for growing a UV LED epitaxial structure, which can improve the crystal quality of the LED epitaxial wafer, reduce non-radiative recombination caused by defects, increase the recombination probability of electrons and holes, improve the internal quantum efficiency, and greatly improve the luminous efficiency.
[0004] The second objective of this invention is to provide a UV LED epitaxial structure.
[0005] One of the objectives of this invention is achieved through the following technical solution:
[0006] A method for growing a UV LED epitaxial structure includes: sequentially growing a buffer layer, an unintentionally doped layer, an n-type doped layer, a multi-quantum-well light-emitting layer, an EBL layer, and a p-type AlGaN layer on a substrate;
[0007] The buffer layer comprises a first AlN layer, a second AlN layer, a third AlN layer, and a fourth AlN layer stacked sequentially, and its growth method is as follows:
[0008] 1) A first AlN layer is grown on the substrate. The growth temperature of the first AlN layer is 800-900℃, the pressure is 50-100 torr, the TMAl flow rate is 100-200 sccm, and the NH3 flow rate is 2-10 slm.
[0009] 2) A second AlN layer is grown on the first AlN layer. The growth temperature of the second AlN layer is 1000-1100℃, the pressure is 50-100 torr, the TMAl flow rate is 200-300 sccm, and the NH3 flow rate is 1-8 slm.
[0010] 3) A third AlN layer is grown on the second AlN layer. The growth temperature of the third AlN layer is 900-1000℃, the pressure is 50-100 torr, the TMAl flow rate is 200-300 sccm, and the NH3 flow rate is 1-8 slm.
[0011] 4) A fourth AlN layer is grown on the third AlN layer. The growth temperature of the fourth AlN layer is 1000-1100℃, the pressure is 50-100tor, the TMAl flow rate is 250-350sccm, and the NH3 flow rate is 1-8slm.
[0012] Furthermore, in step 2), the NH3 flow rate for growing the second AlN layer is less than the NH3 flow rate for growing the first AlN layer;
[0013] In step 3), the NH3 flow rate for growing the third AlN layer is less than the NH3 flow rate for growing the first AlN layer;
[0014] In step 4), the NH3 flow rate for growing the fourth AlN layer is less than that for growing the second and third AlN layers; the TMAl flow rate for growing the fourth AlN layer is greater than that for growing the second and third AlN layers.
[0015] Furthermore, the thickness of the first AlN layer is 10-50 nm;
[0016] The thickness of the second AlN layer is 20-80 nm;
[0017] The thickness of the third AlN layer is 20-80 nm;
[0018] The thickness of the fourth AlN layer is 150-300 nm.
[0019] Furthermore, the thickness of the second AlN layer is greater than the thickness of the first AlN layer; the thickness of the third AlN layer is greater than the thickness of the first AlN layer.
[0020] Furthermore, the unintentionally doped layer is any one or a combination of two or more of AlN, AlGaN, and InAlGaN; the growth temperature of the unintentionally doped layer is 1000–1400°C.
[0021] Furthermore, the n-type doped layer is any one or a combination of two or more of AlN, AlGaN, and InAlGaN; the growth temperature of the n-type doped layer is 1000–1400℃, and the Si doping concentration in the n-type doped layer is 1e18–3e19 Atom / cm³. 3 .
[0022] Furthermore, the multi-quantum-well light-emitting layer is (Al x Ga 1-x N / Al y Ga 1-y N) n Where x is 0.2 to 0.4, y is 0.3 to 0.6, and n is 5 to 10; the growth temperature of the multi-quantum well light-emitting layer is 900 to 1100℃.
[0023] Furthermore, the EBL layer is any one or a combination of two or more of p-AlGaN, p-AlInGaN, and p-AlN, and the Mg doping concentration in the EBL layer is 5e18 to 3.5e19 atm / cm³. 3 ;
[0024] The Mg doping concentration in the p-type AlGaN layer can be 5e18 to 1e20 Atom / cm³. 3 ;
[0025] The substrate is any one of sapphire, silicon, and silicon carbide.
[0026] Furthermore, the thickness of the unintentionally doped layer is 2.0–4.0 μm;
[0027] The thickness of the n-type doped layer is 1–4 μm;
[0028] In the multi-quantum-well light-emitting layer, the potential well Al x Ga 1-x The thickness of N is 2–4 nm, and the barrier Al y Ga 1-y The thickness of N is 3–10 nm;
[0029] The thickness of the EBL layer is 30–80 nm;
[0030] The thickness of the p-type AlGaN layer is 30–150 nm.
[0031] The second objective of this invention is achieved by the following technical solution:
[0032] A UV LED epitaxial structure is fabricated using the growth method described above.
[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0034] The present invention discloses a method for growing a UV LED epitaxial structure. The grown buffer layer comprises a first AlN layer, a second AlN layer, a third AlN layer, and a fourth AlN layer stacked sequentially, resulting in a buffer layer with good crystal quality and surface finish. This buffer layer can improve the crystal quality of the LED epitaxial wafer, reduce nonradiative recombination caused by defects, increase the recombination probability of electrons and holes, improve the internal quantum efficiency, and greatly improve the luminous efficiency.
[0035] The present invention provides a UV LED epitaxial structure with good crystal quality and high luminous efficiency. Attached Figure Description
[0036] Figure 1 This is a schematic diagram of a UV LED epitaxial structure according to the present invention.
[0037] Among them, 1 is the substrate; 2 is the buffer layer; 3 is the unintentionally doped layer; 4 is the n-type doped layer; 5 is the multi-quantum well light-emitting layer; 51 is the potential well; 52 is the potential barrier; 6 is the EBL layer; and 7 is the p-type AlGaN layer. Detailed Implementation
[0038] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.
[0039] Example 1
[0040] A UV LED epitaxial structure, such as Figure 1 As shown, it includes: a buffer layer 2, an unintentionally doped layer 3, an n-type doped layer 4, a multi-quantum-well light-emitting layer 5, an EBL layer 6, and a p-type AlGaN layer 7 grown sequentially on a substrate 1.
[0041] Furthermore, the substrate 1 is sapphire;
[0042] The buffer layer 2 comprises a first AlN layer, a second AlN layer, a third AlN layer, and a fourth AlN layer stacked sequentially.
[0043] The unintentionally doped layer 3 is AlN.
[0044] The n-type doped layer 4 is AlGaN;
[0045] The multi-quantum-well light-emitting layer 5 is (Al) x Ga 1-x N / Al y Ga 1-y N) n Where x is 0.2, y is 0.3, and n is 5;
[0046] The EBL layer 6 is a p-AlGaN barrier layer.
[0047] The growth method of the aforementioned UV LED epitaxial structure is as follows:
[0048] 1. Preparation of growth buffer layer 2:
[0049] 1) A first AlN layer is grown on substrate 1. The growth temperature of the first AlN layer is 800℃, the pressure is 50 torr, the TMAl flow rate is 100 sccm, and the NH3 flow rate is 3 slm. The thickness of the first AlN layer is 10-20 nm.
[0050] 2) A second AlN layer is grown on the first AlN layer. The growth temperature of the second AlN layer is 1000℃, the pressure is 50 torr, the TMAl flow rate is 200 sccm, and the NH3 flow rate is 2 slm. The thickness of the second AlN layer is 30-40 nm.
[0051] 3) A third AlN layer is grown on the second AlN layer. The growth temperature of the third AlN layer is 900℃, the pressure is 50 torr, the TMAl flow rate is 200 sccm, and the NH3 flow rate is 2 slm. The thickness of the third AlN layer is 30-40 nm.
[0052] 4) A fourth AlN layer is grown on the third AlN layer. The growth temperature of the fourth AlN layer is 1000℃, the pressure is 50tor, the TMAl flow rate is 250sccm, and the NH3 flow rate is 1slm. The thickness of the fourth AlN layer is 150-200nm.
[0053] 2. Growth of unintentionally doped layer 3 and n-type doped layer 4:
[0054] The unintentionally doped layer 3 is AlN, and its absorption wavelength is less than that of UV L1 ED; the growth temperature of the unintentionally doped layer 3 is 1000℃, and the thickness of the unintentionally doped layer 3 is 2.0~3μm.
[0055] The n-type doped layer 4 is AlGaN, and its absorption wavelength is shorter than that of UV LEDs; the growth temperature of the n-type doped layer 4 is 1000℃, and the Si doping concentration in the n-type doped layer 4 is 1e18~3e19 Atom / cm³. 3 The thickness of the n-type doped layer 4 is 1–2 μm.
[0056] 3. Growth of a multi-quantum-well light-emitting layer 5:
[0057] Furthermore, the multi-quantum-well light-emitting layer 5 is (Al)x Ga 1-x N / Al y Ga 1-y N) n The growth temperature is 900–1100℃;
[0058] The multi-quantum-well light-emitting layer 5 is composed of a multi-quantum-well structure stacked sequentially over multiple periods. The multi-quantum-well structure includes interconnected potential wells 51 (Al). x Ga 1-x N) and barrier 52 (Al) y Ga 1-y N);
[0059] In the multi-quantum well structure, the total thickness of the potential well 51 is 2-4 nm, and the total thickness of the barrier 52 is 3-10 nm; in the multi-quantum well light-emitting layer 5, the period n is 5.
[0060] 4. Growth of EBL layer 6:
[0061] The EBL layer 6 is a p-AlGaN barrier layer, and the Mg doping concentration in the EBL layer 6 is 5e18~3.5e19 Atom / cm³. 3 The thickness of the EBL layer 6 is 30–80 nm.
[0062] 5. Growth of p-type AlGaN layer 7:
[0063] The Mg doping concentration in the p-type AlGaN layer 7 can be 5e18~1e20 Atom / cm³. 3 The thickness is 30–150 nm.
[0064] The present invention provides a UV LED epitaxial structure that can improve the crystal quality of LED epitaxial wafers, reduce nonradiative recombination caused by defects, increase the recombination probability of electrons and holes, improve internal quantum efficiency, and greatly improve luminous efficiency.
[0065] Example 2
[0066] A UV LED epitaxial structure, such as Figure 1 As shown, it includes: a buffer layer 2, an unintentionally doped layer 3, an n-type doped layer 4, a multi-quantum-well light-emitting layer 5, an EBL layer 6, and a p-type AlGaN layer 7 grown sequentially on a substrate 1.
[0067] Furthermore, the substrate 1 is a silicon substrate 1;
[0068] The buffer layer 2 comprises a first AlN layer, a second AlN layer, a third AlN layer, and a fourth AlN layer stacked sequentially.
[0069] The unintentionally doped layer 3 is AlGaN;
[0070] The n-type doped layer 4 is InAlGaN;
[0071] The multi-quantum-well light-emitting layer 5 is (Al) x Ga 1-x N / Al y Ga 1-y N) n Where x is 0.3, y is 0.5, and n is 8;
[0072] The EBL layer 6 is a p-AlInGaN barrier layer.
[0073] The growth method of the aforementioned UV LED epitaxial structure is as follows:
[0074] 1. Preparation of growth buffer layer 2:
[0075] 1) A first AlN layer is grown on substrate 1. The growth temperature of the first AlN layer is 850℃, the pressure is 75 torr, the TMAl flow rate is 150 sccm, and the NH3 flow rate is 6 slm. The thickness of the first AlN layer is 20-30 nm.
[0076] 2) A second AlN layer is grown on the first AlN layer. The growth temperature of the second AlN layer is 1050℃, the pressure is 70 torr, the TMAl flow rate is 250 sccm, and the NH3 flow rate is 4 slm. The thickness of the second AlN layer is 40-50 nm.
[0077] 3) A third AlN layer is grown on the second AlN layer. The growth temperature of the third AlN layer is 950℃, the pressure is 70 torr, the TMAl flow rate is 250 sccm, and the NH3 flow rate is 4 slm. The thickness of the third AlN layer is 40-50 nm.
[0078] 4) A fourth AlN layer is grown on the third AlN layer. The growth temperature of the fourth AlN layer is 1050℃, the pressure is 50-100tor, the TMAl flow rate is 300sccm, and the NH3 flow rate is 2slm. The thickness of the fourth AlN layer is 200-300nm.
[0079] 2. Growth of unintentionally doped layer 3 and n-type doped layer 4:
[0080] The unintentionally doped layer 3 is AlGaN, and its absorption wavelength is less than that of UV LED; the growth temperature of the unintentionally doped layer 3 is 1200℃, and the thickness of the unintentionally doped layer 3 is 3.0~4.0μm.
[0081] The n-type doped layer 4 is InAlGaN, and its absorption wavelength is shorter than that of UV LEDs; the growth temperature of the n-type doped layer 4 is 1200℃, and the Si doping concentration in the n-type doped layer 4 is 1e18~3e19 Atom / cm³. 3 The thickness of the n-type doped layer 4 is 2–3 μm.
[0082] 3. Growth of a multi-quantum-well light-emitting layer 5:
[0083] Furthermore, the multi-quantum-well light-emitting layer 5 is (Al) x Ga 1-x N / Al y Ga 1-y N) n The growth temperature is 900–1100℃;
[0084] The multi-quantum-well light-emitting layer 5 is composed of a multi-quantum-well structure stacked sequentially over multiple periods. The multi-quantum-well structure includes interconnected potential wells 51 (Al). x Ga 1-x N) and barrier 52 (Al) y Ga 1-y N);
[0085] In the multi-quantum-well structure, the total thickness of the potential well 51 is 2-4 nm, and the total thickness of the barrier 52 is 3-10 nm; in the multi-quantum-well light-emitting layer 5, the period n is 8.
[0086] 4. Growth of EBL layer 6:
[0087] The EBL layer 6 is a p-AlInGaN barrier layer, and the Mg doping concentration in the EBL layer 6 is 5e18~3.5e19 Atom / cm³. 3 The thickness of the EBL layer 6 is 30–80 nm.
[0088] 5. Growth of p-type AlGaN layer 7:
[0089] The Mg doping concentration in the p-type AlGaN layer 7 can be 5e18~1e20 Atom / cm³. 3 The thickness is 30–150 nm.
[0090] The present invention provides a UV LED epitaxial structure that can improve the crystal quality of LED epitaxial wafers, reduce nonradiative recombination caused by defects, increase the recombination probability of electrons and holes, improve internal quantum efficiency, and greatly improve luminous efficiency.
[0091] Example 3
[0092] A UV LED epitaxial structure, such as Figure 1As shown, it includes: a buffer layer 2, an unintentionally doped layer 3, an n-type doped layer 4, a multi-quantum-well light-emitting layer 5, an EBL layer 6, and a p-type AlGaN layer 7 grown sequentially on a substrate 1.
[0093] Furthermore, the substrate 1 is silicon carbide;
[0094] The buffer layer 2 comprises a first AlN layer, a second AlN layer, a third AlN layer, and a fourth AlN layer stacked sequentially.
[0095] The unintentionally doped layer 3 is InAlGaN;
[0096] The n-type doped layer 4 is InAlGaN;
[0097] The multi-quantum-well light-emitting layer 5 is (Al) x Ga 1-x N / Al y Ga 1-y N) n Where x is 0.4, y is 0.6, and n is 10;
[0098] The EBL layer 6 is a p-AlN barrier layer.
[0099] The growth method of the aforementioned UV LED epitaxial structure is as follows:
[0100] 1. Preparation of growth buffer layer 2:
[0101] 1) A first AlN layer is grown on substrate 1. The growth temperature of the first AlN layer is 900℃, the pressure is 100 torr, the TMAl flow rate is 200 sccm, and the NH3 flow rate is 10 slm. The thickness of the first AlN layer is 40-50 nm.
[0102] 2) A second AlN layer is grown on the first AlN layer. The growth temperature of the second AlN layer is 1100℃, the pressure is 100 torr, the TMAl flow rate is 300 sccm, and the NH3 flow rate is 8 slm. The thickness of the second AlN layer is 70-80 nm.
[0103] 3) A third AlN layer is grown on the second AlN layer. The growth temperature of the third AlN layer is 1000℃, the pressure is 100 torr, the TMAl flow rate is 300 sccm, and the NH3 flow rate is 8 slm. The thickness of the third AlN layer is 70-80 nm.
[0104] 4) A fourth AlN layer is grown on the third AlN layer. The growth temperature of the fourth AlN layer is 1100℃, the pressure is 100tor, the TMAl flow rate is 350sccm, and the NH3 flow rate is 6slm. The thickness of the fourth AlN layer is 200-300nm.
[0105] 2. Growth of unintentionally doped layer 3 and n-type doped layer 4:
[0106] The unintentionally doped layer 3 is InAlGaN, and its absorption wavelength is less than that of UV LED; the growth temperature of the unintentionally doped layer 3 is 1400℃, and the thickness of the unintentionally doped layer 3 is 3.0~4.0μm.
[0107] The n-type doped layer 4 is InAlGaN, and its absorption wavelength is shorter than that of UV LEDs; the growth temperature of the n-type doped layer 4 is 1400℃, and the Si doping concentration in the n-type doped layer 4 is 1e18~3e19 Atom / cm³. 3 The thickness of the n-type doped layer 4 is 3–4 μm.
[0108] 3. Growth of a multi-quantum-well light-emitting layer 5:
[0109] Furthermore, the multi-quantum-well light-emitting layer 5 is (Al) x Ga 1-x N / Al y Ga 1-y N) n The growth temperature is 900–1100℃;
[0110] The multi-quantum-well light-emitting layer 5 is composed of a multi-quantum-well structure stacked sequentially over multiple periods. The multi-quantum-well structure includes interconnected potential wells 51 (Al). x Ga 1-x N) and barrier 52 (Al) y Ga 1-y N);
[0111] In a multi-quantum-well structure, the potential well 51Al x Ga 1-x N has a total thickness of 3-4 nm, and the barrier 52 has a total thickness of 5-10 nm; in the multi-quantum well light-emitting layer 5, the period n is 10.
[0112] 4. Growth of EBL layer 6:
[0113] The EBL layer 6 is a p-AlN barrier layer, and the Mg doping concentration in the EBL layer 6 is 5e18~3.5e19 Atom / cm³. 3 The thickness of the EBL layer 6 is 50-80 nm.
[0114] 5. Growth of p-type AlGaN layer 7:
[0115] The Mg doping concentration in the p-type AlGaN layer 7 can be 5e18~1e20 Atom / cm³. 3 The thickness is 30–150 nm.
[0116] The present invention provides a UV LED epitaxial structure that can improve the crystal quality of LED epitaxial wafers, reduce nonradiative recombination caused by defects, increase the recombination probability of electrons and holes, improve internal quantum efficiency, and greatly improve luminous efficiency.
[0117] Example 4
[0118] A UV LED epitaxial structure, such as Figure 1 As shown, it includes: a buffer layer 2, an unintentionally doped layer 3, an n-type doped layer 4, a multi-quantum-well light-emitting layer 5, an EBL layer 6, and a p-type AlGaN layer 7 grown sequentially on a substrate 1.
[0119] Furthermore, the substrate 1 is a silicon substrate 1;
[0120] The buffer layer 2 comprises a first AlN layer, a second AlN layer, a third AlN layer, and a fourth AlN layer stacked sequentially.
[0121] The unintentionally doped layer 3 is an AlN-AlGaN composite layer;
[0122] The n-type doped layer 4 is an AlGaN superlattice layer;
[0123] The multi-quantum-well light-emitting layer 5 is (Al) x Ga 1-x N / Al y Ga 1-y N) n Where x is 0.3, y is 0.5, and n is 7;
[0124] The EBL layer 6 is a p-type AlN-AlGaN composite barrier layer.
[0125] The growth method of the aforementioned UV LED epitaxial structure is as follows:
[0126] 1. Preparation of growth buffer layer 2:
[0127] 1) A first AlN layer is grown on substrate 1. The growth temperature of the first AlN layer is 850℃, the pressure is 70 torr, the TMAl flow rate is 150 sccm, and the NH3 flow rate is 6 slm. The thickness of the first AlN layer is 30-40 nm.
[0128] 2) A second AlN layer is grown on the first AlN layer. The growth temperature of the second AlN layer is 1050℃, the pressure is 70 torr, the TMAl flow rate is 250 sccm, and the NH3 flow rate is 5 slm. The thickness of the second AlN layer is 40-50 nm.
[0129] 3) A third AlN layer is grown on the second AlN layer. The growth temperature of the third AlN layer is 950℃, the pressure is 70 torr, the TMAl flow rate is 240ccm, and the NH3 flow rate is 4slm. The thickness of the third AlN layer is 50-60nm.
[0130] 4) A fourth AlN layer is grown on the third AlN layer. The growth temperature of the fourth AlN layer is 1050℃, the pressure is 70tor, the TMAl flow rate is 280sccm, and the NH3 flow rate is 3slm. The thickness of the fourth AlN layer is 200-300nm.
[0131] 2. Growth of unintentionally doped layer 3 and n-type doped layer 4:
[0132] The unintentionally doped layer 3 is a stacked AlN-AlGaN composite layer, and the absorption wavelength of its material is less than that of UV LED; the growth temperature of the unintentionally doped layer 3 is 1300℃, and the thickness of the unintentionally doped layer 3 is 2.5~3.5μm.
[0133] The n-type doped layer 4 is an AlGaN superlattice layer, and its absorption wavelength is shorter than that of a UV LED; the growth temperature of the n-type doped layer 4 is 1300℃, and the Si doping concentration in the n-type doped layer 4 is 1e18~3e19 Atom / cm³. 3 The thickness of the n-type doped layer 4 is 2–3 μm.
[0134] 3. Growth of a multi-quantum-well light-emitting layer 5:
[0135] Furthermore, the multi-quantum-well light-emitting layer 5 is (Al) x Ga 1-x N / Al y Ga 1-y N) n The growth temperature is 900–1100℃;
[0136] The multi-quantum-well light-emitting layer 5 is composed of a multi-quantum-well structure stacked sequentially over multiple periods. The multi-quantum-well structure includes interconnected potential wells 51 (Al). x Ga 1-x N) and barrier 52 (Al) y Ga 1-y N);
[0137] In the multi-quantum well structure, the total thickness of the potential well 51 is 2-4 nm, and the total thickness of the barrier 52 is 5-10 nm; in the multi-quantum well light-emitting layer 5, the period n is 7.
[0138] 4. Growth of EBL layer 6:
[0139] The EBL layer 6 is a p-type AlN-AlGaN composite barrier layer, and the Mg doping concentration in the EBL layer 6 is 5e18~3.5e19 Atom / cm³. 3 The thickness of the EBL layer 6 is 50-80 nm.
[0140] 5. Growth of p-type AlGaN layer 7:
[0141] The Mg doping concentration in the p-type AlGaN layer 7 can be 5e18~1e20 Atom / cm³. 3 The thickness is 60–100 nm.
[0142] The present invention provides a UV LED epitaxial structure that can improve the crystal quality of LED epitaxial wafers, reduce nonradiative recombination caused by defects, increase the recombination probability of electrons and holes, improve internal quantum efficiency, and greatly improve luminous efficiency.
[0143] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.
Claims
1. A method for growing a UV LED epitaxial structure, characterized in that, include: A buffer layer, an unintentionally doped layer, an n-type doped layer, a multi-quantum-well light-emitting layer, an EBL layer, and a p-type AlGaN layer are sequentially grown on the substrate. The buffer layer comprises a first AlN layer, a second AlN layer, a third AlN layer, and a fourth AlN layer stacked sequentially, and its growth method is as follows: 1) A first AlN layer is grown on the substrate. The growth temperature of the first AlN layer is 800-900℃, the pressure is 50-100 torr, the TMAl flow rate is 100-200 sccm, and the NH3 flow rate is 2-10 slm. 2) A second AlN layer is grown on the first AlN layer. The growth temperature of the second AlN layer is 1000-1100℃, the pressure is 50-100 torr, the TMAl flow rate is 200-300 sccm, and the NH3 flow rate is 1-8 slm. 3) A third AlN layer is grown on the second AlN layer. The growth temperature of the third AlN layer is 900-1000℃, the pressure is 50-100 torr, the TMAl flow rate is 200-300 sccm, and the NH3 flow rate is 1-8 slm. 4) A fourth AlN layer is grown on the third AlN layer. The growth temperature of the fourth AlN layer is 1000-1100℃, the pressure is 50-100tor, the TMAl flow rate is 250-350sccm, and the NH3 flow rate is 1-8slm.
2. The method for growing a UV LED epitaxial structure as described in claim 1, characterized in that, In step 2), the NH3 flow rate for growing the second AlN layer is less than the NH3 flow rate for growing the first AlN layer; In step 3), the NH3 flow rate for growing the third AlN layer is less than the NH3 flow rate for growing the first AlN layer; In step 4), the NH3 flow rate for growing the fourth AlN layer is less than that for growing the second and third AlN layers; the TMAl flow rate for growing the fourth AlN layer is greater than that for growing the second and third AlN layers.
3. The method for growing a UV LED epitaxial structure as described in claim 1 or 2, characterized in that, The thickness of the first AlN layer is 10-50 nm; The thickness of the second AlN layer is 20-80 nm; The thickness of the third AlN layer is 20-80 nm; The thickness of the fourth AlN layer is 150-300 nm.
4. The method for growing a UV LED epitaxial structure as described in claim 3, characterized in that, The thickness of the second AlN layer is greater than the thickness of the first AlN layer; the thickness of the third AlN layer is greater than the thickness of the first AlN layer.
5. The method for growing a UV LED epitaxial structure as described in claim 1, characterized in that, The unintentionally doped layer is any one or a combination of two or more of AlN, AlGaN, and InAlGaN; the growth temperature of the unintentionally doped layer is 1000–1400℃.
6. The method for growing a UV LED epitaxial structure as described in claim 1, characterized in that, The n-type doped layer is any one or a combination of two or more of AlN, AlGaN, and InAlGaN; the growth temperature of the n-type doped layer is 1000–1400℃, and the Si doping concentration in the n-type doped layer is 1e18–3e19 Atom / cm³. 3 .
7. The method for growing a UV LED epitaxial structure as described in claim 1, characterized in that, The multi-quantum-well light-emitting layer is (Al) x Ga 1-x N / Al y Ga 1-y N) n Where x is 0.2 to 0.4, y is 0.3 to 0.6, and n is 5 to 10; the growth temperature of the multi-quantum well light-emitting layer is 900 to 1100℃.
8. The method for growing a UV LED epitaxial structure as described in claim 1, characterized in that, The EBL layer is any one or a combination of two or more of p-AlGaN, p-AlInGaN, and p-AlN, and the Mg doping concentration in the EBL layer is 5e18 to 3.5e19 atm / cm³. 3 ; The Mg doping concentration in the p-type AlGaN layer can be 5e18 to 1e20 Atm / cm³. 3 ; The substrate is any one of sapphire, silicon, and silicon carbide.
9. The method for growing a UV LED epitaxial structure as described in any one of claims 5-8, characterized in that, The thickness of the unintentionally doped layer is 2.0–4.0 μm; The thickness of the n-type doped layer is 1–4 μm; In the multi-quantum-well light-emitting layer, the potential well Al x Ga 1-x The thickness of N is 2–4 nm, and the barrier Al y Ga 1-y The thickness of N is 3–10 nm; The thickness of the EBL layer is 30–80 nm; The thickness of the p-type AlGaN layer is 30–150 nm.
10. A UV LED epitaxial structure, characterized in that, It is made by the growth method of the UV LED epitaxial structure according to any one of claims 1-9.