InGaN red light LED device capable of realizing low blue shift under large current based on barrier layer high-temperature growth and preparation method of InGaN red light LED device

Abstract

The invention discloses an InGaN red light LED device for realizing low blue shift under large current based on barrier layer high-temperature growth and a preparation method thereof, and belongs to the technical field of red light LEDs. The InGaN red light LED device comprises a substrate, a GaN body material layer, a lower structure layer of an active region, the active region, a p-type AlGaN electron barrier layer and a p-type region, the active region comprises a blue light quantum well layer-blue light barrier layer composite layer and a red light quantum well layer-red light barrier layer composite layer; the growth temperature of the red light barrier layer is 905 DEG C or above. According to the invention, the technical path that quantum dots are formed based on the annealing effect after high-temperature growth of the barrier layer is adopted, and the preparation of the low-blue-shift InGaN red light LED device under large current can be realized.

Description

Technical Field

[0001] This invention relates to an InGaN red LED device and its fabrication method based on high-temperature growth of a barrier layer to achieve low blue shift under high current, belonging to the field of red LED technology. Background Technology

[0002] In the field of LED technology, the rise of new display technologies such as AR / VR has placed revolutionary demands on the performance indicators of display devices, among which a significant increase in resolution is one of the most prominent requirements. Currently, in LED technology, the InGaN material system for blue and green light, and the AlGaInP material system for red light, are becoming increasingly mature. However, AlGaInP material has the characteristic of high carrier mobility. This characteristic means that when the chip size is miniaturized, more carriers will participate in the nonradiative recombination process on the sidewalls, resulting in a sharp decline in the luminous efficiency of the device. In addition, AlGaInP and InGaN materials face technical bottlenecks in monolithic integration. Therefore, the performance and integration compatibility of red Micro-LEDs, essential for achieving full-color Micro-LED chip integration, still require further optimization (A. Cheng, Z. Hao, C. Sun, et al., “Recent progresses on InGaN red micro-LEDs for display,” Progress in Quantum Electronics 102 (100575 (2025).). Due to the lower carrier mobility in high-In-content InGaN materials, their size effect is relatively insignificant, and their performance at high temperatures is relatively better. Furthermore, the use of InGaN materials for all full-color applications solves the difficulty of monolithic integration of RGB three-color LEDs. Therefore, InGaN red LEDs have become a hot topic of interest in both industry and academia.

[0003] Because new display technologies such as AR require LEDs to operate at high current densities, and InGaN red LEDs suffer from severe quantum confinement Stark effect (QCSE) and bandgap filling effect (A. Cheng, Z. Hao, C. Sun, et al., “Recent progresses on InGaN red micro-LEDs for display,” Progress in Quantum Electronics 102(100575 (2025).), InGaN red LEDs face a serious blue shift problem under high current. Although current techniques for suppressing the blue shift problem of InGaN red LEDs have shown some effectiveness in specific scenarios, they still have multi-dimensional technical defects and cannot simultaneously meet the comprehensive requirements of next-generation displays for device efficiency and process complexity: Firstly, the scheme of using nanowire (NW) active regions (Y. Xiao, Y. Wu, M. Reddeppa, et al., “Spectrally Pure, High Operational Dynamic Range, Deep Red Micro-LEDs,” NanoLetters 24(41), 12900-12906). (2024).), although relying on low-dimensional structures to achieve strong carrier localization to reduce blue shift, the uniformity control of NW arrays and electrode contact fabrication are difficult, facing problems such as high process complexity and high cost when fabricating on a large scale, making it difficult to meet the needs of industrial-grade mass production; secondly, the growth technology based on semi-polar / non-polar substrates (S.-WH Chen, Y.-M. Huang, KJ Singh, et al., “Full-color micro-LED display with high color stability using semipolar (20-21) InGaN LEDs and quantum-dotphotoresist,” Photonics Research 8(5), 630-636) (2020). Although it can reduce the blue shift caused by QCSE from the root, if the substrate is non-traditional crystal orientation, its mechanical processing is prone to introduce surface damage, which leads to a decrease in the crystal quality of the epitaxial layer. In addition, the In doping efficiency of InGaN layer on semi-polar / non-polar substrates is low and the surface dynamics process is complex, which makes the device efficiency generally lower than that of c-plane substrate devices. At the same time, the high cost of special substrates also limits its commercial application.

[0004] Developing novel techniques to suppress the blue shift problem in InGaN red LEDs, in order to fabricate InGaN red LED devices with low blue shift under high current, remains one of the urgent problems to be solved in this field. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide an InGaN red LED device with low blue shift under high current based on high-temperature growth of a barrier layer, and a method for its fabrication. The present invention employs a technical approach based on the formation of quantum dots through annealing after high-temperature growth of a barrier layer, enabling the fabrication of an InGaN red LED device with low blue shift under high current.

[0006] To achieve the above objectives, the first aspect of the present invention provides an InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, comprising, from bottom to top: a substrate, a GaN bulk material layer grown on the substrate, a lower structure layer of the active region grown on the GaN bulk material layer, an active region grown on the lower structure layer of the active region, a p-type AlGaN electron blocking layer grown on the active region, and a p-type region grown on the p-type AlGaN electron blocking layer; wherein, the active region includes a composite layer of a blue quantum well layer and a composite layer of a red quantum well layer and a red quantum well layer, wherein the composite layer of the red quantum well layer and the red quantum well layer is grown on the composite layer of the blue quantum well layer and the blue quantum well layer in one cycle; the material of the red quantum well layer includes InGaN material; and the growth temperature of the red quantum well layer is above 905°C.

[0007] This invention discovers that when the growth temperature of the red light barrier layer is above 905°C, the high-temperature growth of the red light barrier layer can promote the migration and redistribution of In atoms in the lower well to form a quantum dot structure, thereby enabling the realization of InGaN red LED devices with low blue shift under high current.

[0008] It should be noted that in this invention, Ga represents gallium; N represents nitrogen; In represents indium; Al represents aluminum; Mg represents magnesium; GaN represents gallium nitride; InGaN represents indium gallium nitride, and the proportions of In, Ga, and N are not specifically indicated; MOCVD represents metal-organic chemical vapor deposition; and QCSE represents quantum confinement Stark effect.

[0009] According to a specific embodiment of the present invention, preferably, the substrate includes a c-plane sapphire substrate to ensure that the GaN material and InGaN material on the substrate are also polar surface materials.

[0010] According to a specific embodiment of the present invention, preferably, the size of the substrate is 2-8 inches, for example, it can be 2 inches, 4 inches, 6 inches or 8 inches, etc.

[0011] According to a specific embodiment of the present invention, preferably, the GaN bulk material layer comprises, from bottom to top: a low-temperature buffer layer grown on the substrate, a high-temperature buffer layer grown on the low-temperature buffer layer, an unintentionally doped GaN layer grown on the high-temperature buffer layer, and an n-type doped GaN layer grown on the unintentionally doped GaN layer.

[0012] According to a specific embodiment of the present invention, preferably, the material of the low-temperature buffer layer includes GaN material, and the growth temperature is 550-600℃.

[0013] According to a specific embodiment of the present invention, preferably, the thickness of the low-temperature buffer layer is 0.2-0.5 μm.

[0014] According to a specific embodiment of the present invention, preferably, the material of the high-temperature buffer layer includes GaN material, and the growth temperature is 1000-1050℃.

[0015] According to a specific embodiment of the present invention, preferably, the thickness of the high-temperature buffer layer is 0.1-0.5 μm.

[0016] According to a specific embodiment of the present invention, preferably, the thickness of the unintentionally doped GaN layer is 2-4 μm.

[0017] According to a specific embodiment of the present invention, preferably, the doping element in the n-type doped GaN layer is silicon, and the silicon doping concentration is 5E18-3E19 cm⁻¹. -3 .

[0018] According to a specific embodiment of the present invention, preferably, the thickness of the n-type doped GaN layer is 1-3 μm.

[0019] According to a specific embodiment of the present invention, preferably, the lower structural layer of the active region includes an InGaN / GaN superlattice layer and / or a low-temperature GaN layer. More preferably, the lower structural layer of the active region includes an InGaN / GaN superlattice layer and a low-temperature GaN layer, wherein the low-temperature GaN layer is grown on the InGaN / GaN superlattice layer, and the active region is grown on the low-temperature GaN layer.

[0020] According to a specific embodiment of the present invention, preferably, the InGaN / GaN superlattice layer comprises an InGaN / GaN superlattice with 2-30 cycles, wherein the InGaN / GaN superlattice comprises an InGaN layer with a thickness of 1-3 nm and a GaN layer with a thickness of 2-15 nm.

[0021] According to a specific embodiment of the present invention, 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 3-8%.

[0022] According to a specific embodiment of the present invention, preferably, the InGaN / GaN superlattice layer is a silicon-doped superlattice layer or an unintentionally doped superlattice layer. More preferably, the InGaN / GaN superlattice layer is a silicon-doped InGaN / GaN superlattice layer, and the silicon doping concentration is 5E18-3E19 cm⁻¹. -3 .

[0023] According to a specific embodiment of the present invention, preferably, the material of the low-temperature GaN layer includes unintentionally doped GaN material, and the growth temperature is 700-850℃, more preferably 820-840℃.

[0024] According to a specific embodiment of the present invention, preferably, the thickness of the low-temperature GaN layer is 0-100 nm, more preferably 5-100 nm.

[0025] According to a specific embodiment of the present invention, preferably, the material of the blue quantum well layer includes unintentionally doped InGaN material, wherein the total number of In and Ga atoms in the unintentionally doped InGaN material is 100%, and the atomic percentage of In is 3-15%.

[0026] According to a specific embodiment of the present invention, preferably, the thickness of the blue quantum well layer is 2-4 nm.

[0027] According to a specific embodiment of the present invention, preferably, the material of the blue light barrier layer includes unintentionally doped GaN material or unintentionally doped InGaN material, and the atomic percentage of In in the blue light barrier layer is 0-10% based on the total number of In (if contained) and Ga atoms in the unintentionally doped GaN material or unintentionally doped InGaN material being 100%.

[0028] According to a specific embodiment of the present invention, preferably, the thickness of the blue light barrier layer is 3-20 nm.

[0029] According to a specific embodiment of the present invention, preferably, the composite layer of blue quantum well layer-blue barrier layer includes 1-3 cycles of blue quantum well layer and blue barrier layer.

[0030] According to a specific embodiment of the present invention, preferably, the material of the red quantum well layer comprises unintentionally doped InGaN material, wherein the total number of In and Ga atoms in the unintentionally doped InGaN material is 100%, and the atomic percentage of In is 30-40%. The red quantum well layer is the main light-emitting structure under electrical injection.

[0031] According to a specific embodiment of the present invention, preferably, the thickness of the red quantum well layer is 2-4 nm.

[0032] According to a specific embodiment of the present invention, preferably, the growth temperature of the red light barrier layer is 905-940℃, more preferably 905-935℃, even more preferably 910-930℃, and especially preferably 915-925℃.

[0033] According to a specific embodiment of the present invention, preferably, the In atoms in the red light quantum well layer migrate and redistribute under the growth temperature conditions of the red light barrier layer to form quantum dots.

[0034] According to a specific embodiment of the present invention, preferably, the material of the red light barrier layer is an unintentionally doped GaN material or an unintentionally doped InGaN material, and the atomic percentage of In in the red light barrier layer is 0-10% based on the total number of In (if contained) and Ga atoms in the unintentionally doped GaN material or the unintentionally doped InGaN material being 100%.

[0035] According to a specific embodiment of the present invention, preferably, the thickness of the red light barrier layer is 3-8 nm.

[0036] According to a specific embodiment of the present invention, preferably, a composite layer of blue quantum well layer-blue barrier layer with several cycles and a composite layer of red quantum well layer-red barrier layer (1 cycle) constitute an integral structure, and the active region includes the integral structure with 1-3 cycles.

[0037] According to a specific embodiment of the present invention, 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 10-30%.

[0038] According to a specific embodiment of the present invention, preferably, the p-type AlGaN electron blocking layer is doped with Mg, and the Mg doping concentration is 1E18-2E20 cm⁻¹. -3 .

[0039] According to a specific embodiment of the present invention, preferably, the thickness of the p-type AlGaN electron blocking layer is 5-30 nm.

[0040] According to a specific embodiment of the present invention, preferably, the material of the p-type region comprises GaN material and is doped with Mg, wherein the Mg doping concentration is 1E18-2E20 cm⁻¹. -3 .

[0041] According to a specific embodiment of the present invention, preferably, the thickness of the p-type region is 100-300 nm.

[0042] According to a specific embodiment of the present invention, preferably, the InGaN red LED device has an injection current density of 1-100 A / cm². 2 Under these conditions, the blue shift of the emission wavelength is less than 20 nm.

[0043] A second aspect of this invention provides a method for fabricating the aforementioned InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, comprising the following steps: (1) Epitaxial growth of GaN bulk material layer on substrate; (2) An active region lower structure layer is epitaxially grown on the GaN bulk material layer; (3) An active region is epitaxially grown on the lower structural layer of the active region, which includes a composite layer of blue quantum well layer-blue barrier layer and a composite layer of red quantum well layer-red barrier layer. In one cycle, the composite layer of red quantum well layer-red barrier layer is grown on the composite layer of blue quantum well layer-blue barrier layer. The material of the red quantum well layer includes InGaN material, and the growth temperature of the red barrier layer is above 905℃. (4) A p-type AlGaN electron blocking layer and a p-type region are epitaxially grown sequentially on the active region to obtain the InGaN red LED device based on high-temperature growth of the barrier layer to achieve low blue shift under high current.

[0044] According to a specific embodiment of the present invention, preferably, step (1) 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 unintentionally doped GaN layer, and an n-type doped GaN layer on a substrate, with growth conditions including: growth pressure of 50-1000 mbar; Ga source flow rate of 10-200 sccm; N source flow rate of 2-60 slm; carrier gas of nitrogen or hydrogen; growth temperature of the low-temperature buffer layer of 550-600℃; growth temperature of the high-temperature buffer layer of 1000-1050℃; growth temperature of the unintentionally doped GaN layer of 1000-1050℃; and growth temperature of the n-type doped GaN layer of 1000-1050℃. More preferably, the doping element in the n-type doped GaN layer is silicon, the doping source includes silane, and the silicon doping concentration is 5E18-3E19 cm⁻¹. -3.

[0045] According to a specific embodiment of the present invention, preferably, step (2) includes: epitaxially growing an InGaN / GaN superlattice layer and / or a low-temperature GaN layer on the GaN bulk material layer using MOCVD epitaxial growth, wherein 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 2-60 slm; a carrier gas of nitrogen or hydrogen; a growth temperature of 700-850℃ for the InGaN / GaN superlattice layer; and a growth temperature of 700-850℃ for the low-temperature GaN layer. More preferably, the InGaN / GaN superlattice layer and the low-temperature GaN layer are epitaxially grown sequentially on the GaN bulk material layer. More preferably, the InGaN / GaN superlattice layer is a silicon-doped superlattice layer, the doping source includes silane, and the silicon doping concentration is 5E18-3E19 cm⁻¹. -3 More preferably, the growth temperature of the low-temperature GaN layer is 820-840℃.

[0046] According to a specific embodiment of the present invention, preferably, step (3) includes: epitaxially growing the active region on the lower structural layer of the active region 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 20-500 sccm; N source flow rate of 2-60 slm; carrier gas of nitrogen or hydrogen; growth temperature of the blue quantum well layer of 780-840℃; growth temperature of the blue barrier layer of 800-870℃; and growth temperature of the red quantum well layer of 680-730℃. Preferably, the growth temperature of the red barrier layer is 905-940℃, more preferably 905-935℃, further preferably 910-930℃, and especially preferably 915-925℃.

[0047] According to a specific embodiment of the present invention, preferably, step (4) includes: epitaxially growing a p-type AlGaN electron blocking layer and a p-type region sequentially on the active region using MOCVD epitaxial growth, wherein the growth conditions include: a growth pressure of 50-1000 mbar; a Ga source flow rate of 10-200 sccm; an Al source flow rate of 10-400 sccm; a N source flow rate of 2-60 slm; a carrier gas of nitrogen or hydrogen; a growth temperature of 900-1000℃ for the p-type AlGaN electron blocking layer; and a growth temperature of 900-1000℃ for the p-type region. More preferably, the p-type AlGaN electron blocking layer is doped with Mg, and the doping source includes Cp2Mg (magnesium pyrocene), with a Mg doping concentration of 1E18-2E20 cm⁻¹. -3More preferably, the p-type region is doped with Mg, and the doping source includes Cp₂Mg (magnesium dicerene), with a Mg doping concentration of 1E₁₈-2E₂₀ cm⁻¹. -3 .

[0048] According to a specific embodiment of the present invention, preferably, the Ga source in steps (1) to (4) may include TMGa (trimethylgallium), TEGa (triethylgallium), etc., the N source may include ammonia, etc., the In source may include TMIn (trimethylindium), etc., and the Al source may include TMAl (trimethylaluminum), etc.

[0049] The present invention has at least the following beneficial effects: This invention proposes a method for achieving low blue shift in the emission wavelength of InGaN red LEDs under high current based on the formation of quantum dots through high-temperature growth and subsequent annealing of a barrier layer. The barrier layer refers to the red light potential barrier layer above the red light quantum well layer, and the high temperature refers to a growth temperature above 905℃. This invention utilizes the sufficient migration kinetic energy (post-annealing effect) of In atoms in the lower red light quantum well layer during the high-temperature barrier layer growth process to locally enrich and form quantum dot structures at certain low potential energy locations, thereby reducing the blue shift of the emission wavelength of the InGaN red LED under high current. Simultaneously, the coverage of the barrier layer during the high-temperature process ensures that the In component does not excessively desorb. Since the migration of In atoms within the red light quantum well layer is accompanied by stress release, and the three-dimensional quantum dots are almost unaffected by the compressive strain of the underlying structure, the formed quantum dots are almost unaffected by the QCSE effect. Therefore, the InGaN red LED prepared by this invention exhibits a very small blue shift in the emission wavelength under high current. Attached Figure Description

[0050] Figure 1 is a schematic diagram of the InGaN red LED device of Example 1.

[0051] Figure 2 TEM images of the InGaN red LED devices of Example 1 and Comparative Example 1.

[0052] Figure 3 The results show the blue shift test results of the emission wavelength of the variable current density in Examples 1, 2 and Comparative Example 1.

[0053] Explanation of icon numbers: 1-Substrate; 2-GaN bulk material layer; 3-Lower structural layer of active region; 4-Active region; 5-p-type AlGaN electron blocking layer; 6-p-type region; 201 - Low-temperature buffer layer; 202 - High-temperature buffer layer; 203 - Unintentionally doped GaN layer; 204 - n-type doped GaN layer; 301 - InGaN / GaN superlattice layer; 302 - Low-temperature GaN layer; 401 - Blue light quantum well layer; 402 - Blue light barrier layer; 403 - Red light quantum well layer; 404 - Red light barrier layer. Detailed Implementation

[0054] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the present invention will now be described in detail below, but this should not be construed as limiting the scope of the invention.

[0055] It should be noted that, unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0056] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0057] It should be understood that the terms “comprising,” “including,” and / or “containing” as used herein specify the presence of the stated features, integers, steps, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

[0058] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0059] Example 1

[0060] This embodiment provides an InGaN red LED device and its fabrication method that achieves low blue shift under high current by forming quantum dots based on high-temperature growth and subsequent annealing of the barrier layer.

[0061] The structure of the InGaN red LED device is as follows: Figure 1 As shown, from bottom to top, it includes: a substrate 1, a GaN bulk material layer 2 grown on the substrate 1, a lower structure layer 3 of the active region grown on the GaN bulk material layer 2, an active region 4 grown on the lower structure layer 3 of the active region, a p-type AlGaN electron blocking layer 5 grown on the active region 4, and a p-type region 6 grown on the p-type AlGaN electron blocking layer 5.

[0062] Substrate 1 is a c-plane sapphire substrate with a size (i.e., diameter) of 4 inches and a thickness of 650 μm.

[0063] The GaN bulk material layer 2 consists of, from bottom to top: a low-temperature buffer layer 201 grown on the substrate 1, a high-temperature buffer layer 202 grown on the low-temperature buffer layer 201, an unintentionally doped GaN layer 203 grown on the high-temperature buffer layer 202, and an n-type doped GaN layer 204 grown on the unintentionally doped GaN layer 203.

[0064] The low-temperature buffer layer 201 is made of GaN material. The thickness of the low-temperature buffer layer 201 is 0.4 μm.

[0065] The high-temperature buffer layer 202 is made of GaN material. The thickness of the high-temperature buffer layer 202 is 0.2 μm.

[0066] The thickness of the unintentionally doped GaN layer 203 is 3 μm.

[0067] The dopant element in the n-type doped GaN layer 204 is silicon, and the silicon doping concentration is 1E19 cm⁻¹. -3 The thickness of the n-type doped GaN layer 204 is 2 μm.

[0068] The lower structure layer 3 of the active region consists of, from bottom to top: InGaN / GaN superlattice layer 301 and low-temperature GaN layer 302.

[0069] The InGaN / GaN superlattice layer 301 consists of 24 periods of InGaN / GaN superlattices. Each InGaN / GaN superlattice comprises an InGaN layer with a thickness of 1.3 nm and a GaN layer with a thickness of 2.5 nm. 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 5%, i.e., In... 0.05 Ga 0.95 N layers.

[0070] InGaN / GaN superlattice layer 301 is a silicon-doped InGaN / GaN superlattice layer with a silicon doping concentration of 1E19cm⁻¹. -3 .

[0071] The material of the low-temperature GaN layer 302 is unintentionally doped GaN. The thickness of the low-temperature GaN layer 302 is 5 nm.

[0072] The active region 4 includes a composite layer of blue quantum well layer 401 and blue barrier layer 402 and a composite layer of red quantum well layer 403 and red barrier layer 404. In one cycle, the composite layer of red quantum well layer 403 and red barrier layer 404 is grown on the composite layer of blue quantum well layer 401 and blue barrier layer 402.

[0073] The blue quantum well layer 401 is made of unintentionally doped InGaN material. Assuming the total number of In and Ga atoms in the unintentionally doped InGaN material is 100%, the percentage of In atoms is 5%, i.e., In... 0.05 Ga 0.95 N. The thickness of the blue quantum well layer 401 is 3 nm.

[0074] The blue light barrier layer 402 is made of unintentionally doped GaN material. The thickness of the blue light barrier layer 402 is 6 nm.

[0075] The composite layer of blue quantum well layer 401-blue barrier layer 402 consists of two cycles of blue quantum well layer 401 and blue barrier layer 402.

[0076] The red quantum well layer 403 is made of unintentionally doped InGaN material. Assuming the total number of In and Ga atoms in the unintentionally doped InGaN material is 100%, the percentage of In atoms is 35%, i.e., In... 0.35 Ga 0.65 N. The thickness of the red quantum well layer 403 is 3 nm.

[0077] The red light barrier layer 404 is made of unintentionally doped GaN. The thickness of the red light barrier layer 404 is 6 nm. The growth temperature of the red light barrier layer 404 is 915℃. In atoms in the red light quantum well layer migrate and redistribute under the growth temperature conditions of the red light barrier layer 404 to form quantum dots.

[0078] The composite layer of the two-cycle blue quantum well layer 401 and blue barrier layer 402, and the composite layer of the one-cycle red quantum well layer 403 and red barrier layer 404, constitute an integral structure, and the two-cycle integral structure constitutes the active region 4.

[0079] 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 5 is 20%, i.e., Al 0.2 Ga 0.8 The N.p-type AlGaN electron blocking layer 5 is doped with Mg, and the Mg doping concentration is 1E20 cm⁻¹. -3 The thickness of the p-type AlGaN electron blocking layer 5 is 10 nm.

[0080] The material of p-type region 6 is GaN, doped with Mg, with a Mg doping concentration of 1E20 cm⁻¹. -3 The thickness of p-type region 6 is 160 nm.

[0081] The fabrication method of this InGaN red LED device includes the following steps: (1) Using MOCVD epitaxial growth, a low-temperature buffer layer 201, a high-temperature buffer layer 202, an unintentionally doped GaN layer 203, and an n-type doped GaN layer 204 were sequentially epitaxially grown on substrate 1 to obtain GaN bulk material layer 2. The growth conditions included: a growth pressure of 200 mbar; a Ga source flow rate of 67 sccm; an N source flow rate of 5 slm; a carrier gas of hydrogen; a growth temperature of 575℃ for the low-temperature buffer layer 201; a growth temperature of 1020℃ for the high-temperature buffer layer 202; a growth temperature of 1040℃ for the unintentionally doped GaN layer 203; and a silicon doping element in the n-type doped GaN layer 204, with silane as the dopant source and a silicon doping concentration of 1E19 cm⁻¹. -3 The growth temperature of the n-type doped GaN layer 204 is 1040℃.

[0082] (2) Using MOCVD epitaxial growth, an InGaN / GaN superlattice layer 301 and a low-temperature GaN layer 302 were epitaxially grown on the GaN bulk material layer 2 to obtain the lower structure layer 3 of the active region. The growth conditions included: a growth pressure of 200 mbar; a Ga source flow rate of 67 sccm; an In source flow rate of 60 sccm; a N source flow rate of 5 slm; and hydrogen as the carrier gas. The InGaN / GaN superlattice layer 301 was a silicon-doped superlattice layer with silane as the doping source and a silicon doping concentration of 1E19 cm⁻¹. -3 The growth temperature of the InGaN / GaN superlattice layer 301 is 830℃; the growth temperature of the low-temperature GaN layer 302 is 830℃.

[0083] (3) Using MOCVD epitaxial growth, the active region 4 is epitaxially grown on the lower structural layer 3 of the active region. The growth conditions of the composite layer of blue quantum well layer 401-blue barrier layer 402 include: growth pressure of 200 mbar; Ga source flow rate of 67 sccm; In source flow rate of 60 sccm; N source flow rate of 5 slm; carrier gas of nitrogen; growth temperature of blue quantum well layer 401 of 820℃; growth temperature of blue barrier layer 402 of 850℃. The growth conditions of the composite layer of red quantum well layer 403-red barrier layer 404 include: growth pressure of 200 mbar; Ga source flow rate of 25 sccm; In source flow rate of 340 sccm; N source flow rate of 5 slm; carrier gas of nitrogen; growth temperature of red quantum well layer 403 of 710℃; growth temperature of red barrier layer 404 of 915℃.

[0084] (4) Using MOCVD epitaxial growth, a p-type AlGaN electron blocking layer 5 and a p-type region 6 were sequentially epitaxially grown on the active region 4. The growth conditions included: a growth pressure of 200 mbar; a Ga source flow rate of 67 sccm; an Al source flow rate of 45 sccm (the Al source was TMAl); an N source flow rate of 5 slm; and hydrogen as the carrier gas. The p-type AlGaN electron blocking layer 5 was doped with Mg, with Cp2Mg as the doping source and a Mg doping concentration of 1E20 cm⁻¹. -3 The growth temperature of the p-type AlGaN electron blocking layer 5 is 945℃; the p-type region 6 is doped with Mg, the doping source is Cp₂Mg, and the Mg doping concentration is 1E₂⁰ cm⁻¹. -3 The growth temperature for p-type region 6 is 945℃.

[0085] In steps (1), (2), and (4) above, the Ga source is TMGa, the N source is ammonia, and the In source is TMIn.

[0086] In step (3) above, the Ga source is TEGa, the N source is ammonia, and the In source is TMIn.

[0087] Example 2

[0088] This embodiment is basically the same as Embodiment 1, except that the growth temperature of the red light barrier layer 404 is increased to 925°C, while the rest is the same as Embodiment 1.

[0089] Comparative Example 1

[0090] This comparative example is basically the same as Example 1, except that the growth temperature of the red light barrier layer 404 is reduced to 880°C, while the rest is the same as Example 1.

[0091] Test case

[0092] In Example 1 and Comparative Example 1, transmission electron microscopy (TEM) analysis was performed after MOCVD epitaxy to determine the formation of quantum dot structures. Subsequently, LED chips with planar dimensions of 500 μm × 850 μm were fabricated from Examples 1, 2, and 1 respectively, and blue shift measurements of the emission wavelength at varying current densities were performed. The LED chip fabrication method was a conventional method in the art, mainly including: optical lithography, mesa etching, passivation, opening electrode windows, and sputtering metal electrodes onto the epitaxial wafer.

[0093] TEM images of Example 1 and Comparative Example 1 are as follows: Figure 2As shown, the red box represents the quantum dot structure. It can be seen that, compared to Comparative Example 1, Example 1 utilizes the sufficient migration kinetic energy (post-annealing) of the In atoms in the lower red light trap during the high-temperature barrier layer growth process to locally enrich and form quantum dot structures at certain low potential energy locations. Since the TEM images of Example 2 and Example 1 are not significantly different, only the TEM image of Example 1 is provided here.

[0094] Blue shift test of emission wavelength with varying current density: The testing system used in this test mainly includes a manual probe station and an integrating sphere. The specific functions and parameters of each module of the testing system are as follows: Manual probe station: Model FormFactor EPS150TRIAX, which realizes the electrical connection between the chip sample and the digital source meter by adjusting the three-dimensional probe holder, and provides support for the integrating sphere; Integrating sphere: Model InstrumentSystems ISP 75, which receives the light emitted by the chip sample.

[0095] The blue shift test results of the peak emission wavelength of the variable current density in Examples 1, 2, and 1 are as follows: Figure 3 As shown, the lower left inset is Example 1 at 10 A / cm 2 Photographs of light emission under current injection. It can be seen that the blue shift of the emission wavelength of Example 1 under high current is significantly smaller than that of Comparative Example 1. However, since the growth temperature of the red barrier layer in Example 2 is slightly higher than that in Example 1, there is a small amount of In component desorption. Therefore, the peak wavelength of Example 2 under different current densities is shorter than that of Example 1. However, the blue shift of the emission wavelength of Example 2 under high current is also significantly smaller than that of Comparative Example 1.

[0096] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, comprising, from bottom to top: The system comprises a substrate, a GaN bulk material layer grown on the substrate, a lower structure layer of the active region grown on the GaN bulk material layer, an active region grown on the lower structure layer of the active region, a p-type AlGaN electron blocking layer grown on the active region, and a p-type region grown on the p-type AlGaN electron blocking layer; wherein the active region includes a composite layer of a blue quantum well layer and a composite layer of a red quantum well layer and a red quantum well layer, and the composite layer of the red quantum well layer and the red quantum well layer is grown on the composite layer of the blue quantum well layer and the blue quantum well layer in one cycle; the material of the red quantum well layer includes InGaN material; and the growth temperature of the red quantum well layer is above 905°C.

2. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 1, wherein... The substrate includes a c-plane sapphire substrate; And / or, the GaN bulk material layer comprises, from bottom to top, a low-temperature buffer layer grown on the substrate, a high-temperature buffer layer grown on the low-temperature buffer layer, an unintentionally doped GaN layer grown on the high-temperature buffer layer, and an n-type doped GaN layer grown on the unintentionally doped GaN layer.

3. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 2, wherein... The material of the low-temperature buffer layer includes GaN material, and the growth temperature is 550-600℃; And / or, the thickness of the low-temperature buffer layer is 0.2-0.5 μm; And / or, the material of the high-temperature buffer layer includes GaN material, and the growth temperature is 1000-1050℃; And / or, the thickness of the high-temperature buffer layer is 0.1-0.5 μm; And / or, the thickness of the unintentionally doped GaN layer is 2-4 μm; And / or, the doping element in the n-type doped GaN layer is silicon, and the silicon doping concentration is 5E18-3E19 cm⁻¹. -3 ; And / or, the thickness of the n-type doped GaN layer is 1-3 μm.

4. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 1, wherein... The underlying structure layer of the active region includes an InGaN / GaN superlattice layer and / or a low-temperature GaN layer.

5. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 4, wherein... The underlying structure of the active region includes an InGaN / GaN superlattice layer and a low-temperature GaN layer, wherein the low-temperature GaN layer is grown on the InGaN / GaN superlattice layer and the active region is grown on the low-temperature GaN layer.

6. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 4 or 5, wherein... The InGaN / GaN superlattice layer comprises an InGaN / GaN superlattice with 2-30 cycles, wherein the InGaN / GaN superlattice comprises an InGaN layer with a thickness of 1-3 nm and a GaN layer with a thickness of 2-15 nm.

7. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 6, 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 3-8%. And / or, the InGaN / GaN superlattice layer is a silicon-doped superlattice layer or an unintentionally doped superlattice layer.

8. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 7, wherein... The InGaN / GaN superlattice layer is a silicon-doped InGaN / GaN superlattice layer with a silicon doping concentration of 5E18-3E19 cm⁻¹. -3 .

9. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 4 or 5, wherein... The material of the low-temperature GaN layer includes unintentionally doped GaN material, and the growth temperature is 700-850℃; And / or, the thickness of the low-temperature GaN layer is 0-100 nm.

10. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 1, wherein... The material of the blue quantum well layer includes unintentionally doped InGaN material, with the total number of In and Ga atoms in the unintentionally doped InGaN material being 100%, the atomic percentage of In is 3-15%. And / or, the thickness of the blue quantum well layer is 2-4 nm; And / or, the material of the blue light barrier layer includes unintentionally doped GaN material or unintentionally doped InGaN material, and the atomic percentage of In in the blue light barrier layer is 0-10%, based on the total number of In and Ga atoms in the unintentionally doped GaN material or unintentionally doped InGaN material being 100%. And / or, the thickness of the blue light barrier layer is 3-20 nm; And / or, the composite layer of blue quantum well layer-blue barrier layer includes 1-3 cycles of blue quantum well layer and blue barrier layer.

11. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 1, wherein... The material of the red quantum well layer includes unintentionally doped InGaN material, with the total number of In and Ga atoms in the unintentionally doped InGaN material being 100%, the atomic percentage of In is 30-40%. And / or, the thickness of the red quantum well layer is 2-4 nm; And / or, the growth temperature of the red light barrier layer is 905-940℃; And / or, the In atoms in the red light quantum well layer migrate and redistribute under the growth temperature conditions of the red light barrier layer to form quantum dots; And / or, the material of the red light barrier layer is unintentionally doped GaN material or unintentionally doped InGaN material, and the atomic percentage of In in the red light barrier layer is 0-10%, based on the total number of In and Ga atoms in the unintentionally doped GaN material or unintentionally doped InGaN material being 100%. And / or, the thickness of the red light barrier layer is 3-8 nm.

12. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 1, wherein... A composite layer of blue quantum well layer-blue quantum barrier layer with several cycles, and a composite layer of red quantum well layer-red quantum barrier layer, constitute an integral structure, and the active region includes 1-3 cycles of the integral structure.

13. The InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in claim 1, wherein... 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 is 10-30%. And / or, the p-type AlGaN electron blocking layer is doped with Mg, and the Mg doping concentration is 1E18-2E20 cm⁻¹. -3 ; And / or, the thickness of the p-type AlGaN electron blocking layer is 5-30 nm; And / or, the material of the p-type region includes GaN material, and is doped with Mg, with a Mg doping concentration of 1E18-2E20 cm⁻¹. -3 ; And / or, the thickness of the p-type region is 100-300 nm.

14. A method for fabricating an InGaN red LED device based on high-temperature growth of a barrier layer to achieve low blue shift under high current, as described in any one of claims 1-13, comprising the following steps: (1) Epitaxial growth of GaN bulk material layer on substrate; (2) An active region lower structure layer is epitaxially grown on the GaN bulk material layer; (3) An active region is epitaxially grown on the lower structural layer of the active region, which includes a composite layer of blue quantum well layer-blue barrier layer and a composite layer of red quantum well layer-red barrier layer. In one cycle, the composite layer of red quantum well layer-red barrier layer is grown on the composite layer of blue quantum well layer-blue barrier layer. The material of the red quantum well layer includes InGaN material, and the growth temperature of the red barrier layer is above 905℃. (4) A p-type AlGaN electron blocking layer and a p-type region are epitaxially grown sequentially on the active region to obtain the InGaN red LED device based on high-temperature growth of the barrier layer to achieve low blue shift under high current.

15. The preparation method according to claim 14, wherein, Step (1) includes: using MOCVD epitaxial growth, a low-temperature buffer layer, a high-temperature buffer layer, an unintentionally doped GaN layer, and an n-type doped GaN layer are epitaxially grown sequentially on the substrate. The growth conditions include: a growth pressure of 50-1000 mbar; a Ga source flow rate of 10-200 sccm; an N source flow rate of 2-60 slm; and a carrier gas of nitrogen or hydrogen. The growth temperature of the low-temperature buffer layer is 550-600℃; the growth temperature of the high-temperature buffer layer is 1000-1050℃; the growth temperature of the unintentionally doped GaN layer is 1000-1050℃; and the growth temperature of the n-type doped GaN layer is 1000-1050℃. And / or, step (2) includes: epitaxially growing an InGaN / GaN superlattice layer and / or a low-temperature GaN layer on the GaN bulk material layer using MOCVD epitaxial growth, 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 2-60 slm; carrier gas of nitrogen or hydrogen; growth temperature of the InGaN / GaN superlattice layer of 700-850℃; and growth temperature of the low-temperature GaN layer of 700-850℃. And / or, step (3) includes: epitaxially growing the active region on the lower structural layer of the active region using MOCVD, with growth conditions including: growth pressure of 50-1000 mbar; Ga source flow rate of 10-200 sccm; In source flow rate of 20-500 sccm; N source flow rate of 2-60 slm; carrier gas of nitrogen or hydrogen; growth temperature of the blue quantum well layer of 780-840℃; growth temperature of the blue barrier layer of 800-870℃; and growth temperature of the red quantum well layer of 680-730℃. And / or, step (4) includes: using MOCVD epitaxial growth, sequentially growing a p-type AlGaN electron blocking layer and a p-type region on the active region, 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 2-60 slm; carrier gas of nitrogen or hydrogen; growth temperature of p-type AlGaN electron blocking layer of 900-1000℃; growth temperature of p-type region of 900-1000℃.

Images