A low-blue-shift InGaN red LED device based on a well-well coupling structure and a preparation method thereof

Abstract

The application provides a low-blue-shift InGaN red LED device based on a well-well coupling structure and a preparation method thereof. The LED device comprises, from bottom to top, a substrate, a buffer layer, an undoped GaN layer, an n-type doped GaN layer, a superlattice layer and / or a low-temperature GaN layer, a wide-shallow quantum well and a tunneling barrier composite layer, an InGaN narrow-deep quantum well and a red light barrier composite layer, and a p-type region. The preparation method of the LED device comprises: epitaxially growing, on the substrate, the buffer layer, the undoped GaN layer, the n-type doped GaN layer, the superlattice layer and / or the low-temperature GaN layer, the wide-shallow quantum well and the tunneling barrier composite layer, the InGaN narrow-deep quantum well and the red light barrier composite layer, and the p-type region in sequence. Through the tunneling effect of carriers, the application maintains the carrier concentration in the light-emitting well, and improves the blue-shift amplitude of the light-emitting wavelength of the InGaN-based red LED.

Description

Technical Field

[0001] This invention relates to a low blue-shift InGaN red LED device based on a trap-trap coupling structure and its fabrication method, belonging to the field of light-emitting diode technology. Background Technology

[0002] In the LED field, the development of new display technologies, represented by AR / VR, has placed entirely new demands on display devices, one of the most significant features being the significantly increased resolution requirements. Of the original red, green, and blue LEDs, blue and green LEDs are based on the InGaN material system, while red LEDs are based on the AlGaInP material system. However, the AlGaInP material system has a very high carrier mobility, leading to more carriers participating in non-radiative recombination on the sidewalls as the chip size decreases, resulting in a rapid decline in luminous efficiency—a phenomenon known as the size-dependent effect. Furthermore, AlGaInP-based LEDs have poor high-temperature performance, facing an efficiency drop of over 90% in Micro-LEDs that may operate at high current densities. The integration of GaAs-based red LEDs and GaN-based blue and green LEDs under conditions of fully miniaturized driving circuits also introduces additional process complexity.

[0003] Therefore, InGaN-based red LEDs have become a hot topic in both industry and academia. Due to the low carrier mobility in GaN materials, their size effect is relatively insignificant, and their performance is relatively better at high temperatures. Prior art documents disclose some red micro-LEDs based on InGaN materials (Hsiao FH, Lee TY, Miao WC, et al. Investigations on the high performance of InGaN red micro-LEDs with single quantum well for visible light communication applications [J]. Discover Nano, 2023, 18 (1): 95.; Pasayat SS, Gupta C, Wong MS, et al. Demonstration of ultra-small(<10μm)632nmred InGaN micro-LEDs with useful on-wafer external quantum efficiency(>0.2%) for mini-displays[J].Applied Physics Express,2020,14(1):011004.;Chen Z,ShengB,Liu F,et al.High-Efficiency InGaN Red Mini-LEDs on Sapphire Toward Full-Color Nitride Displays:Effect of Strain Modulation[J].Advanced FunctionalMaterials, 2023:2300042.).

[0004] However, the high In composition active region required for red LEDs is usually accompanied by a very serious blue shift problem, that is, the emission wavelength gradually transitions from red light to yellow light or even green light as the injection current density increases. This is a common problem in GaN-based LEDs, but it is more serious in red LEDs, to the point that it cannot meet the basic requirements of display. The inherent physical mechanism that causes this situation is the piezoelectric polarization caused by the inherent compressive stress of GaN / InGaN materials. Traditional LED growth is based on c-plane sapphire substrates, where the GaN surface is a polar surface. When the GaN material is subjected to external stress and deforms, polarization occurs, i.e., piezoelectric polarization. The existence of this built-in polarized electric field will have an adverse effect on the luminous efficiency of GaN-based LEDs. Under the combined effect of spontaneous polarization and piezoelectric polarization, a polarized electric field opposite to the c-axis

[0001] will be generated in the InGaN quantum well of the active region of the polar GaN-based LED, causing the energy band of the active region to tilt, reducing the overlap integral of the electron-hole wave function, decreasing the carrier recombination probability, severely suppressing the IQE of the LED, and causing a red shift in wavelength. This phenomenon is known as the quantum confinement Stark effect (QCSE).

[0005] The QCSE effect causes a red shift in the emission wavelength of LEDs at low current densities. Furthermore, as the injected current (carrier concentration) increases further, the polarization electric field is shielded, resulting in a blue shift in wavelength. Specifically for red LEDs, due to the higher In content and more severe lattice mismatch in the active region, the QCSE is more pronounced, typically exhibiting a blue shift of over 50 nm (injection current density 1-1000 A / cm²). 2 This is one of the inherent defects of the InGaN material system. If it is not improved, it will not be able to meet the normal RGB display requirements, which will greatly hinder the further development of small-size display technology. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a low-blue-shift InGaN red LED device based on a trap-trap coupling structure and its fabrication method. This invention can improve the blue-shift amplitude of the emission wavelength of InGaN-based red LEDs.

[0007] To achieve the above objectives, the first aspect of the present invention provides a low blue-shift InGaN red LED device based on a well-well coupling structure, comprising, from bottom to top: a substrate, a buffer layer grown on the substrate, an undoped GaN layer grown on the buffer layer, an n-type doped GaN layer grown on the undoped GaN layer, a superlattice layer and / or a low-temperature GaN layer grown on the n-type doped GaN layer, a wide and shallow quantum well and tunneling barrier composite layer grown on the superlattice layer or the low-temperature GaN layer, an InGaN narrow and deep quantum well and red light barrier composite layer grown on the wide and shallow quantum well and tunneling barrier composite layer, and a p-type region grown on the InGaN narrow and deep quantum well and red light barrier composite layer.

[0008] It should be noted that in this invention, InGaN refers to indium gallium nitride, and does not specifically refer to the ratio of In, Ga, and N elements therein.

[0009] It should be noted that in this invention, the thickness of the wide and shallow quantum well layer is its width, and the thickness of the InGaN narrow and deep quantum well layer is its width. The depth of the wide and shallow quantum well layer and the InGaN narrow and deep quantum well layer refers to the depth of the "potential well" in the band structure, and there is no depth in a geometric sense.

[0010] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the substrate includes a c-plane sapphire substrate or a c-plane GaN substrate to ensure that the GaN material and InGaN material on the substrate are both polar surface materials.

[0011] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the substrate is 2-8 inches in size, for example, 2 inches, 4 inches, 6 inches or 8 inches.

[0012] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the buffer layer includes a low-temperature buffer layer, and optionally includes a high-temperature buffer layer; when a high-temperature buffer layer is included, it is located above the low-temperature buffer layer; the material of the low-temperature buffer layer includes GaN material, and the growth temperature is 500-550℃; the material of the high-temperature buffer layer includes GaN material, and the growth temperature is 1000-1050℃.

[0013] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the thickness of the low-temperature buffer layer is 0.2-0.5 μm, and the thickness of the high-temperature buffer layer is 0-0.5 μm.

[0014] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the thickness of the undoped GaN layer is 1-3 μm.

[0015] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the thickness of the n-type doped GaN layer is 2-4 μm.

[0016] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the doping element in the n-type doped GaN layer is silicon.

[0017] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the superlattice layer comprises an InGaN / GaN superlattice with 2-30 periods.

[0018] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the InGaN / GaN superlattice comprises an InGaN layer with a thickness of 1-3 nm and a GaN layer with a thickness of 2-6 nm.

[0019] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, with the total number of In and Ga atoms in the InGaN layer of the InGaN / GaN superlattice being 100%, the In content in the InGaN layer is 2-10%.

[0020] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the superlattice layer is a silicon-doped superlattice layer or an undoped superlattice layer.

[0021] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the material of the low-temperature GaN layer includes undoped GaN material, and the growth temperature is 700-850℃, more preferably 820-840℃.

[0022] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the thickness of the low-temperature GaN layer is 5-100 nm.

[0023] In the aforementioned low blue-shift InGaN red LED device based on a well-well coupling structure, preferably, the wide and shallow quantum well and tunneling barrier composite layer comprises a wide and shallow quantum well layer and a tunneling barrier layer.

[0024] In the aforementioned low blue-shift InGaN red LED device based on a well-well coupling structure, preferably, the material of the wide and shallow quantum well layer includes InGaN material, with the total number of In and Ga atoms in the InGaN material being 100%, the atomic percentage of In is 5-20%, more preferably 5-15%.

[0025] In the aforementioned low blue-shift InGaN red LED device based on a well-well coupling structure, preferably, the wide and shallow quantum well layer is a silicon-doped wide and shallow quantum well layer or an undoped wide and shallow quantum well layer.

[0026] In the aforementioned low blue-shift InGaN red LED device based on a well-well coupling structure, preferably, the thickness of the wide and shallow quantum well layer is 5-15 nm.

[0027] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the material of the tunneling barrier layer includes GaN material or InGaN material, and the atomic percentage of In in the tunneling barrier layer is 0-10%, with the total number of In (if contained) and Ga atoms in the GaN material or InGaN material being 100%.

[0028] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the tunneling barrier layer is a silicon-doped tunneling barrier layer or an undoped tunneling barrier layer.

[0029] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the thickness of the tunneling barrier layer is 2-5 nm.

[0030] In the aforementioned low blue-shift InGaN red LED device based on a well-well coupling structure, preferably, the InGaN narrow-deep quantum well and red barrier composite layer comprises an InGaN narrow-deep quantum well layer and a red barrier layer.

[0031] In the aforementioned low blue-shift InGaN red LED device based on a well-well coupling structure, preferably, the material of the InGaN narrow deep quantum well layer includes InGaN material, with the total number of In and Ga atoms in the InGaN material being 100%, the atomic percentage of In is 25-40%, more preferably 25-35%.

[0032] In the aforementioned low blue-shift InGaN red LED device based on a well-well coupling structure, preferably, the InGaN narrow-deep quantum well layer is an undoped InGaN narrow-deep quantum well layer.

[0033] In the aforementioned low blue-shift InGaN red LED device based on a well-well coupling structure, preferably, the thickness of the InGaN narrow-depth quantum well layer is 2-4 nm.

[0034] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the material of the red barrier layer includes GaN material or InGaN material, and the atomic percentage of In in the red barrier layer is 0-10% based on the total number of In (if contained) and Ga atoms in the GaN material or InGaN material being 100%.

[0035] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the red barrier layer is an undoped red barrier layer.

[0036] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the thickness of the red barrier layer is 5-20 nm.

[0037] In the aforementioned low blue-shift InGaN red LED device based on a well-well coupling structure, preferably, the wide shallow quantum well and tunneling barrier composite layer and the narrow deep InGaN quantum well and red light barrier composite layer are grown alternately, with the number of alternating growth cycles being 1-5 cycles.

[0038] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the p-type region includes a lower p-type AlGaN electron blocking layer and an upper p-type GaN layer.

[0039] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, with the total number of Al and Ga atoms in AlGaN being 100%, the atomic percentage of Al in the p-type AlGaN electron blocking layer is 5-40%.

[0040] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the thickness of the p-type AlGaN electron blocking layer is 10-100 nm.

[0041] In the aforementioned low blue-shift InGaN red LED device based on a well-well coupling structure, preferably, the doping element in the p-type GaN layer is Mg.

[0042] In the aforementioned low blue-shift InGaN red LED device based on a trap-trap coupling structure, preferably, the thickness of the p-type GaN layer is 20-150 nm.

[0043] A second aspect of the present invention provides a method for fabricating the aforementioned low blue-shift InGaN red LED device based on a well-well coupling structure, comprising the following steps:

[0044] (1) A buffer layer, an undoped GaN layer, an n-type doped GaN layer, a superlattice layer and / or a low-temperature GaN layer are epitaxially grown sequentially on the substrate.

[0045] (2) Epitaxially growing a wide and shallow quantum well and tunneling barrier composite layer on the superlattice layer or the low-temperature GaN layer;

[0046] (3) An InGaN narrow and deep quantum well and red light barrier composite layer is epitaxially grown on the wide and shallow quantum well and tunneling barrier composite layer.

[0047] (4) A p-type region is epitaxially grown on the InGaN narrow deep quantum well and red light barrier composite layer to obtain the low blue shift InGaN red light LED device based on the well-well coupling structure.

[0048] In the above preparation method, preferably, step (1) specifically includes: using MOCVD (metal-organic chemical vapor deposition) epitaxial growth method, sequentially epitaxially growing a low-temperature buffer layer, a high-temperature buffer layer, an undoped GaN layer, an n-type doped GaN layer, and a superlattice layer and / or a low-temperature GaN layer on the substrate, with growth conditions including: growth pressure of 50-1000 mbar, Ga source flow rate of 10-200 sccm; In source flow rate of 20-300 sccm; N source flow rate of 2-10 slm; carrier gas of nitrogen or hydrogen; growth temperature of the low-temperature buffer layer of 500-550℃; growth temperature of the high-temperature buffer layer of 1000-1050℃; growth temperature of the undoped GaN layer of 1020-1050℃; growth temperature of the n-type doped GaN layer of 1000-1050℃; growth temperature of the superlattice layer of 700-850℃; and growth temperature of the low-temperature GaN layer of 700-850℃. More preferably, the doping element in the n-type doped GaN layer is silicon, the doping source includes silane, and the doping concentration is 1E18-5E18 cm⁻¹. -3 More preferably, when the superlattice layer is a silicon-doped superlattice layer, the doping source includes silane, and the doping concentration is 1E18-5E18 cm⁻¹. -3 .

[0049] In the above preparation method, preferably, step (2) specifically includes: epitaxially growing a wide and shallow quantum well and tunneling barrier composite layer on the superlattice layer or the low-temperature GaN layer using MOCVD epitaxial growth, wherein the growth conditions include: growth pressure of 50-1000 mbar, Ga source flow rate of 10-200 sccm, In source flow rate of 20-300 sccm, N source flow rate of 2-10 slm, carrier gas of nitrogen or hydrogen, growth temperature of the wide and shallow quantum well layer of 700-850℃, and growth temperature of the tunneling barrier layer of 700-850℃. More preferably, when the wide and shallow quantum well layer is a silicon-doped wide and shallow quantum well layer, the doping source includes silane, and the doping concentration is 1E18-5E18 cm⁻¹. -3 More preferably, when the tunneling barrier layer is a silicon-doped tunneling barrier layer, the doping source includes silane, and the doping concentration is 1E18-5E18 cm⁻¹. -3 .

[0050] In the above preparation method, preferably, step (3) specifically includes: using MOCVD epitaxial growth, growing an InGaN narrow-deep quantum well and a red light barrier composite layer on the wide-shallow quantum well and tunneling barrier composite layer, with the following growth conditions: growth pressure of 50-1000 mbar, Ga source flow rate of 10-200 sccm, In source flow rate of 20-400 sccm, N source flow rate of 2-10 slm, carrier gas of nitrogen or hydrogen, growth temperature of the InGaN narrow-deep quantum well layer of 650-730℃, and growth temperature of the red light barrier layer of 700-850℃.

[0051] In the above preparation method, preferably, step (3) further includes: alternatingly growing the wide shallow quantum well and tunneling barrier composite layer and the InGaN narrow deep quantum well and red light barrier composite layer for 1-5 cycles.

[0052] In the above preparation method, preferably, step (4) specifically includes: using MOCVD epitaxial growth, sequentially growing a p-type AlGaN electron blocking layer and a p-type GaN layer on the InGaN narrow-depth quantum well and red light barrier composite layer, with growth conditions including: growth pressure of 50-1000 mbar, Ga source flow rate of 10-200 sccm; Al source flow rate of 10-400 sccm; N source flow rate of 2-10 slm; carrier gas of nitrogen or hydrogen; growth temperature of the p-type AlGaN electron blocking layer of 900-1000℃; and growth temperature of the p-type GaN layer of 900-1000℃. More preferably, the doping element in the p-type GaN layer is Mg, the doping source includes Cp2Mg (magnesium dicerene), and the doping concentration is 1E18-2E20 cm⁻¹. -2 .

[0053] In the above preparation method, preferably, the Ga source in steps (1) to (4) may include TMGa (trimethylgallium), the N source may include ammonia, the In source may include TMIn (trimethylindium), and the Al source may include TMAl (trimethylaluminum).

[0054] The technical solution of the present invention has at least the following beneficial effects:

[0055] This invention, based on quantum well-coupled structures, develops a "wide-shallow quantum well-tunneling barrier-narrow-deep quantum well" structure. In this structure, the wide-shallow quantum well layer does not participate in luminescence under conventional electrical injection conditions, while simultaneously accumulating excess carriers. The tunneling barrier layer provides the possibility for carrier tunneling between the wide-shallow and narrow-deep wells; its thinness is sufficient for carrier tunneling. The InGaN narrow-deep quantum well layer provides the main carrier radiative recombination region and is grown on a polar surface, serving as the primary luminescent structure under electrical injection. This structure releases the stress in the high-In-component active region, increasing the In-component incorporation efficiency. Simultaneously, under low injection rates, carriers are captured by the narrow-deep red quantum well with stronger trapping capabilities, while under high injection rates, more carriers are injected into the wide-shallow blue quantum well (but this well does not participate in luminescence), maintaining a relatively constant carrier concentration in the red quantum well and minimizing the adverse effects of spontaneous QCSE in the GaN quantum well. Therefore, the InGaN-based red LED based on a polar surface substrate in this invention maintains the carrier concentration in the light-emitting trap through the carrier tunneling effect, thereby improving the blue shift amplitude of the emission wavelength of the InGaN-based red LED and enhancing its performance to meet the high requirements of next-generation display technologies. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the low blue-shift InGaN red LED device based on a trap-trap coupling structure provided in Example 1.

[0057] Figure 2 This is a schematic diagram of the band structure and carrier injection of a low blue-shift InGaN red LED device based on a trap-trap coupling structure under low injection current, as shown in Example 1.

[0058] Figure 3 This is a schematic diagram of the band structure and carrier injection of a low blue-shift InGaN red LED device based on a trap-trap coupling structure under high injection current, as shown in Example 1.

[0059] Figure 4 This is a schematic diagram of the InGaN red LED device in Comparative Example 1.

[0060] Figure 5The current density-peak wavelength curves of the LED devices in Example 1 and Comparative Example 1 are shown.

[0061] Explanation of icon numbers:

[0062] 1-Substrate; 2-Buffer layer; 3-Undoped GaN layer; 4-n-type doped GaN layer; 5-Superlattice layer; 6-Low-temperature GaN layer; 7-Wide and shallow quantum well and tunneling barrier composite layer; 8-InGaN narrow and deep quantum well and red light barrier composite layer; 9-p-type region;

[0063] 201 - Low-temperature buffer layer; 202 - High-temperature buffer layer;

[0064] 701 - Wide and shallow quantum well layer; 702 - Tunneling barrier layer;

[0065] 801-InGaN narrow-depth quantum well layer; 802-red light barrier layer;

[0066] 901-p type AlGaN electron blocking layer; 902-p type GaN layer. Detailed Implementation

[0067] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0068] Example 1

[0069] This embodiment provides a low blue-shift InGaN red LED device based on a well-well coupling structure, such as... Figure 1 As shown, from bottom to top, it includes: a substrate 1, a buffer layer 2 grown on the substrate 1, an undoped GaN layer 3 grown on the buffer layer 2, an n-type doped GaN layer 4 grown on the undoped GaN layer 3, a superlattice layer 5 grown on the n-type doped GaN layer 4, a low-temperature GaN layer 6 grown on the superlattice layer 5, a wide and shallow quantum well and tunneling barrier composite layer 7 grown on the low-temperature GaN layer 6, an InGaN narrow and deep quantum well and red light barrier composite layer 8 grown on the wide and shallow quantum well and tunneling barrier composite layer 7, and a p-type region 9 grown on the InGaN narrow and deep quantum well and red light barrier composite layer 8.

[0070] Substrate 1 is a c-plane sapphire substrate.

[0071] The substrate 1 is 2 inches in size.

[0072] Buffer layer 2 includes a lower low-temperature buffer layer 201 and an upper high-temperature buffer layer 202. The low-temperature buffer layer 201 is made of GaN material and grown at a temperature of 525°C; the high-temperature buffer layer 202 is also made of GaN material and grown at a temperature of 1020°C. Both the low-temperature buffer layer 201 and the high-temperature buffer layer 202 have a thickness of 0.5 μm. Both the low-temperature buffer layer 201 and the high-temperature buffer layer 202 are undoped GaN material layers.

[0073] The thickness of the undoped GaN layer 3 is 2 μm.

[0074] The thickness of the n-type doped GaN layer 4 is 3 μm. The dopant element in the n-type doped GaN layer 4 is silicon, and the doping concentration is 2E18cm⁻¹. -2 .

[0075] Superlattice layer 5 comprises an InGaN / GaN superlattice with 20 periods. The InGaN / GaN superlattice consists of a 2nm thick InGaN layer and a 3nm thick GaN layer. The InGaN layer is specifically made of In... 0.06 Ga 0.94 N. Assuming the total number of In and Ga atoms in the InGaN layer of the InGaN / GaN superlattice is 100%, the In content in the InGaN layer is 6%. Superlattice layer 5 is a silicon-doped superlattice layer with a doping concentration of 2E18cm⁻¹. -2 .

[0076] The material of the low-temperature GaN layer 6 consists of undoped GaN material, and the growth temperature is 830℃. The thickness of the low-temperature GaN layer 6 is 7nm.

[0077] The shallow quantum well and tunneling barrier composite layer 7 includes a shallow quantum well layer 701 and a tunneling barrier layer 702.

[0078] The shallow quantum well layer 701 is made of InGaN material, specifically In 0.14 Ga 0.86 N, taking the total number of In and Ga atoms in the InGaN material as 100%, has an In atomic percentage of 14%. The shallow quantum well layer 701 is a silicon-doped shallow quantum well layer with a doping concentration of 2E18 cm⁻¹. -2 The thickness of the shallow quantum well layer 701 is 7 nm.

[0079] The tunneling barrier layer 702 is made of GaN, and the atomic percentage of In in the tunneling barrier layer 702 is 0%. The tunneling barrier layer 702 is a silicon-doped tunneling barrier layer with a doping concentration of 2E18 cm⁻¹. -2 The thickness of the tunneling barrier layer 702 is 3 nm.

[0080] The InGaN narrow-deep quantum well and red barrier composite layer 8 includes an InGaN narrow-deep quantum well layer 801 and a red barrier layer 802.

[0081] The InGaN narrow deep quantum well layer 801 is made of InGaN material, specifically In 0.30 Ga 0.70 N, taking the total number of In and Ga atoms in the InGaN material as 100%, with In atoms accounting for 30%. The InGaN narrow and deep quantum well layer 801 is an undoped InGaN narrow and deep quantum well layer. The thickness of the InGaN narrow and deep quantum well layer 801 is 3 nm.

[0082] The red barrier layer 802 is made of GaN, and the atomic percentage of In in the red barrier layer 802 is 0%. The red barrier layer 802 is an undoped red barrier layer. The thickness of the red barrier layer 802 is 15 nm.

[0083] Three cycles of alternating growth of a wide, shallow quantum well and tunneling barrier composite layer 7 and an InGaN narrow, deep quantum well and red light barrier composite layer 8.

[0084] The p-type region 9 includes a p-type AlGaN electron blocking layer 901 located at the bottom and a p-type GaN layer 902 located at the top.

[0085] Assuming the total number of Al and Ga atoms in AlGaN is 100%, the atomic percentage of Al in the p-type AlGaN electron blocking layer 901 is 30%. The thickness of the p-type AlGaN electron blocking layer 901 is 15 nm.

[0086] The dopant element in the p-type GaN layer 902 is Mg, with a doping concentration of 1E19 cm⁻¹. -2 The thickness of the p-type GaN layer 902 is 45 nm.

[0087] This embodiment also provides a method for fabricating the low blue-shift InGaN red LED device based on the well-well coupling structure described above, which includes the following steps:

[0088] (1) Using MOCVD epitaxial growth, a low-temperature buffer layer 201, a high-temperature buffer layer 202, an undoped GaN layer 3, an n-type doped GaN layer 4, a superlattice layer 5, and a low-temperature GaN layer 6 were sequentially epitaxially grown on substrate 1. The growth conditions included: a growth pressure of 200 mbar, a Ga source of TMGa with a source flow rate of 67 sccm, an N source of ammonia with a source flow rate of 5 slm, and a carrier gas of hydrogen. The growth temperature of the low-temperature buffer layer 201 was 525℃; the growth temperature of the high-temperature buffer layer 202 was 1020℃; the growth temperature of the undoped GaN layer 3 was 1040℃; the growth temperature of the n-type doped GaN layer 4 was 1040℃, the dopant element was silicon, the dopant source was silane, and the doping concentration was 2E18cm⁻¹. -2 The growth temperature of superlattice layer 5 is 830℃, the In source is TMI with a source flux of 60 sccm, the dopant is silicon with a dopant source of silane and a doping concentration of 2E18 cm⁻¹. -2 The growth temperature of the low-temperature GaN layer 6 is 830℃.

[0089] (2) A wide and shallow quantum well and tunneling barrier composite layer 7 was epitaxially grown on a low-temperature GaN layer 6 using MOCVD. The growth conditions included: a growth pressure of 200 mbar, a Ga source of TMGa with a source flow rate of 67 sccm, an In source of TMIn with a source flow rate of 180 sccm, an N source of ammonia with a source flow rate of 5 slm, and a nitrogen carrier gas. The growth temperature of the wide and shallow quantum well layer 701 was 740 °C, the dopant element was silicon, the dopant source was silane, and the doping concentration was 2E18 cm⁻¹. -2 The tunneling barrier layer 702 was grown at a temperature of 830℃, with silicon as the dopant, silane as the dopant source, and a doping concentration of 2E18 cm⁻¹. -2 .

[0090] (3) Using MOCVD epitaxial growth, InGaN narrow deep quantum well and red barrier composite layer 8 were epitaxially grown on the wide shallow quantum well and tunneling barrier composite layer 7. The growth conditions included: growth pressure of 200 mbar, Ga source of TMGa with a source flow rate of 67 sccm, In source of TMIn with a source flow rate of 400 sccm, N source of ammonia with a source flow rate of 5 slm, and carrier gas of nitrogen; the growth temperature of InGaN narrow deep quantum well layer 801 was 700℃; the growth temperature of red barrier layer 802 was 830℃; and the wide shallow quantum well and tunneling barrier composite layer 7 and InGaN narrow deep quantum well and red barrier composite layer 8 were grown alternately for 3 cycles.

[0091] (4) Using MOCVD epitaxial growth, a p-type AlGaN electron blocking layer 901 and a p-type GaN layer 902 were sequentially epitaxially grown on the InGaN narrow-depth quantum well and red light barrier composite layer 8. The growth conditions included: a growth pressure of 200 mbar, a Ga source of TMGa with a source flow rate of 67 sccm, an Al source of TMAl with a source flow rate of 40 sccm, an N source of ammonia with a source flow rate of 5 slm, and a carrier gas of hydrogen. The growth temperature of the p-type AlGaN electron blocking layer 901 was 945℃. The growth temperature of the p-type GaN layer 902 was 945℃, the doping element was Mg, the doping source was Cp2Mg, and the doping concentration was 1E19 cm⁻¹. -2 Thus, the low blue-shift InGaN red LED device based on the trap-trap coupling structure was obtained.

[0092] Figure 2 This is a schematic diagram of the band structure and carrier injection of the low blue-shift InGaN red LED device based on a trap-trap coupling structure under low injection current in this embodiment. Figure 3 This diagram illustrates the band structure and carrier injection characteristics of a low-blue-shift InGaN red LED device with a well-well coupling structure under high injection current, as described in this embodiment. Figure 2 and Figure 3 As shown, when the carrier concentration is low, most carriers are captured by the red light narrow deep well with stronger trapping ability, which does not affect the luminescence efficiency at low current density. When the carrier concentration is high, most carriers are captured by the wide shallow well that does not participate in the electric injection luminescence, which acts as a "reservoir" for carriers. They are then injected back into the red light narrow deep well through tunneling, which to a certain extent maintains that the carrier concentration in the red light narrow deep well does not change significantly, that is, the emission wavelength does not produce a large blue shift.

[0093] Comparative Example 1

[0094] This comparative example provides an InGaN red LED device, the structure of which is as follows: Figure 4 As shown, the structure of this device is basically the same as that of Example 1, except that it does not include the wide and shallow quantum well and tunneling barrier composite layer 7.

[0095] The fabrication method of this InGaN red LED device is basically the same as that in Example 1, except that step (2) is not included, and step (3) involves growing the InGaN narrow deep quantum well and red light barrier composite layer 8 for 3 cycles.

[0096] Test case

[0097] The LED devices of Example 1 and Comparative Example 1 were simulated using SiLENSe software, and the current density-peak wavelength curves were obtained, as shown below. Figure 5 As shown. By Figure 5As can be seen, the emission wavelength of the high-indium quantum well without a well-well coupling structure in Comparative Example 1 exhibits a blue shift exceeding 30 nm as the current density increases. However, the emission wavelength of the quantum well with a well-well coupling structure in Example 1 shows almost no blue shift with changing current density. Therefore, this invention improves the blue shift amplitude of the emission wavelength of InGaN-based red LEDs, thereby enhancing the performance of InGaN-based red LEDs and enabling them to meet the high requirements of next-generation display technologies.

Claims

1. A low blue-shift InGaN red LED device based on a well-well coupling structure, comprising, from bottom to top: The substrate, a buffer layer grown on the substrate, an undoped GaN layer grown on the buffer layer, an n-type doped GaN layer grown on the undoped GaN layer, a superlattice layer and / or a low-temperature GaN layer grown on the n-type doped GaN layer, a wide and shallow quantum well and tunneling barrier composite layer grown on the superlattice layer or the low-temperature GaN layer, an InGaN narrow and deep quantum well and red light barrier composite layer grown on the wide and shallow quantum well and tunneling barrier composite layer, and a p-type region grown on the InGaN narrow and deep quantum well and red light barrier composite layer. The wide and shallow quantum well and tunneling barrier composite layer includes a wide and shallow quantum well layer and a tunneling barrier layer. The material of the wide and shallow quantum well layer includes InGaN material, with the total number of In and Ga atoms in the InGaN material being 100%, the atomic percentage of In is 5-20%; the thickness of the wide and shallow quantum well layer is 5-15 nm. The material of the tunneling barrier layer includes GaN or InGaN, and with the total number of In and Ga atoms in the GaN or InGaN material being 100%, the atomic percentage of In in the tunneling barrier layer is 0-10%; the thickness of the tunneling barrier layer is 2-5 nm. The InGaN narrow-deep quantum well and red light barrier composite layer includes an InGaN narrow-deep quantum well layer and a red light barrier layer. The InGaN narrow-deep quantum well layer is made of InGaN material, with the total number of In and Ga atoms in the InGaN material being 100%, and the atomic percentage of In being 25-40%; the thickness of the InGaN narrow-deep quantum well layer is 2-4 nm. The material of the red light barrier layer includes GaN or InGaN. With the total number of In and Ga atoms in the GaN or InGaN material being 100%, the atomic percentage of In in the red light barrier layer is 0-10%; the thickness of the red light barrier layer is 5-20 nm.

2. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The substrate includes a c-plane sapphire substrate or a c-plane GaN substrate.

3. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The buffer layer includes a low-temperature buffer layer and optionally a high-temperature buffer layer; when a high-temperature buffer layer is included, it is located above the low-temperature buffer layer; the material of the low-temperature buffer layer includes GaN material, and the growth temperature is 500-550 ℃; the material of the high-temperature buffer layer includes GaN material, and the growth temperature is 1000-1050 ℃.

4. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 3, wherein, The thickness of the low-temperature buffer layer is 0.2-0.5 μm, and the thickness of the high-temperature buffer layer is 0-0.5 μm.

5. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The thickness of the undoped GaN layer is 1-3 μm.

6. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The thickness of the n-type doped GaN layer is 2-4 μm.

7. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The doping element in the n-type doped GaN layer is silicon.

8. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The superlattice layer comprises an InGaN / GaN superlattice with 2-30 periods.

9. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 8, wherein, The InGaN / GaN superlattice comprises an InGaN layer with a thickness of 1-3 nm and a GaN layer with a thickness of 2-6 nm.

10. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 9, wherein, Assuming the total number of In and Ga atoms in the InGaN layer of the InGaN / GaN superlattice is 100%, the In content in the InGaN layer is 2-10%.

11. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The superlattice layer is a silicon-doped superlattice layer or an undoped superlattice layer.

12. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The material of the low-temperature GaN layer includes undoped GaN material, and the growth temperature is 700-850 ℃.

13. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The thickness of the low-temperature GaN layer is 5-100 nm.

14. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The shallow quantum well layer is either a silicon-doped shallow quantum well layer or an undoped shallow quantum well layer.

15. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The tunneling barrier layer is either a silicon-doped tunneling barrier layer or an undoped tunneling barrier layer.

16. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The InGaN narrow-depth quantum well layer is an undoped InGaN narrow-depth quantum well layer.

17. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The red light barrier layer is an undoped red light barrier layer.

18. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The wide and shallow quantum well and tunneling barrier composite layer and the narrow and deep InGaN quantum well and red light barrier composite layer are grown alternately, with the number of alternating growth cycles being 1-5 cycles.

19. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 1, wherein, The p-type region includes a p-type AlGaN electron blocking layer located at the bottom and a p-type GaN layer located at the top.

20. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 19, wherein, With the total number of Al and Ga atoms in AlGaN being 100%, the atomic percentage of Al in the p-type AlGaN electron blocking layer is 5-40%.

21. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 19, wherein, The thickness of the p-type AlGaN electron blocking layer is 10-100 nm.

22. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 19, wherein, The doping element in the p-type GaN layer is Mg.

23. The low blue-shift InGaN red LED device based on a well-well coupling structure according to claim 19, wherein, The thickness of the p-type GaN layer is 20-150 nm.

24. A method for fabricating a low blue-shift InGaN red LED device based on a well-well coupling structure as described in any one of claims 1-23, comprising the following steps: (1) A buffer layer, an undoped GaN layer, an n-type doped GaN layer, a superlattice layer and / or a low-temperature GaN layer are epitaxially grown sequentially on the substrate; (2) A wide and shallow quantum well and tunneling barrier composite layer is epitaxially grown on the superlattice layer or the low-temperature GaN layer; (3) An InGaN narrow deep quantum well and red light barrier composite layer is epitaxially grown on the wide shallow quantum well and tunneling barrier composite layer; (4) A p-type region is epitaxially grown on the InGaN narrow deep quantum well and red light barrier composite layer to obtain the low blue shift InGaN red light LED device based on the well-well coupling structure.

25. The preparation method according to claim 24, wherein, Step (1) specifically includes: using MOCVD epitaxial growth, sequentially growing a low-temperature buffer layer, a high-temperature buffer layer, an undoped GaN layer, an n-type doped GaN layer, and a superlattice layer and / or a low-temperature GaN layer on the substrate. The growth conditions include: a growth pressure of 50-1000 mbar, a Ga source flow rate of 10-200 sccm, an In source flow rate of 20-300 sccm, an N source flow rate of 2-10 slm, and a carrier gas of nitrogen or hydrogen. The growth temperature of the low-temperature buffer layer is 500-550 ℃; the growth temperature of the high-temperature buffer layer is 1000-1050 ℃; the growth temperature of the undoped GaN layer is 1020-1050 ℃; the growth temperature of the n-type doped GaN layer is 1000-1050 ℃; the growth temperature of the superlattice layer is 700-850 ℃; and the growth temperature of the low-temperature GaN layer is 700-850 ℃.

26. The preparation method according to claim 25, wherein, The doping element in the n-type doped GaN layer is silicon, and the doping source includes silane, with a doping concentration of 1E18-5E18 cm⁻¹. -3 .

27. The preparation method according to claim 25, wherein, When the superlattice layer is a silicon-doped superlattice layer, the doping source includes silane, and the doping concentration is 1E18-5E18 cm⁻¹. -3 .

28. The preparation method according to claim 24, wherein, Step (2) specifically includes: using MOCVD epitaxial growth, a wide and shallow quantum well and tunneling barrier composite layer is epitaxially grown on the superlattice layer or the low-temperature GaN layer. The growth conditions include: growth pressure of 50-1000 mbar, Ga source flow rate of 10-200 sccm, In source flow rate of 20-300 sccm, N source flow rate of 2-10 slm, carrier gas of nitrogen or hydrogen, growth temperature of the wide and shallow quantum well layer of 700-850 ℃, and growth temperature of the tunneling barrier layer of 700-850 ℃.

29. The preparation method according to claim 28, wherein, When the shallow quantum well layer is a silicon-doped shallow quantum well layer, the doping source includes silane, and the doping concentration is 1E18-5E18 cm⁻¹. -3 .

30. The preparation method according to claim 28, wherein, When the tunneling barrier layer is a silicon-doped tunneling barrier layer, the doping source includes silane, and the doping concentration is 1E18-5E18 cm⁻¹. -3 .

31. The preparation method according to claim 24, wherein, Step (3) specifically includes: using MOCVD epitaxial growth, InGaN narrow deep quantum well and red light barrier composite layer are epitaxially grown on the wide shallow quantum well and tunneling barrier composite layer. The growth conditions include: growth pressure of 50-1000 mbar, Ga source flow rate of 10-200 sccm, In source flow rate of 20-400 sccm, N source flow rate of 2-10 slm, carrier gas of nitrogen or hydrogen, growth temperature of InGaN narrow deep quantum well layer of 650-730℃, and growth temperature of red light barrier layer of 700-850℃.

32. The preparation method according to claim 24, wherein, Step (4) specifically includes: using MOCVD epitaxial growth, a p-type AlGaN electron blocking layer and a p-type GaN layer are epitaxially grown sequentially on the InGaN narrow-depth quantum well and red light barrier composite layer. The growth conditions include: growth pressure of 50-1000 mbar, Ga source flow rate of 10-200 sccm, Al source flow rate of 10-400 sccm, N source flow rate of 2-10 slm, carrier gas of nitrogen or hydrogen, growth temperature of p-type AlGaN electron blocking layer of 900-1000 ℃, and growth temperature of p-type GaN layer of 900-1000 ℃.

33. The preparation method according to claim 32, wherein, The dopant element in the p-type GaN layer is Mg, with Cp₂Mg as the doping source and a doping concentration of 1E¹⁸-2E²⁰ cm⁻¹. -3 .

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