Blue-green dual-band led epitaxial wafer, preparation method thereof and blue-green dual-band led

Abstract

The application discloses a blue-green dual-band LED epitaxial wafer and a preparation method and a blue-green dual-band LED thereof, and relates to the technical field of semiconductors. The multi-quantum well light-emitting layer of the blue-green dual-band LED epitaxial wafer comprises a green light multi-quantum well layer, a blue light multi-quantum well layer and a blue light multi-coupling well layer which are stacked in sequence; the green light multi-quantum well layer comprises periodically and alternately stacked green light InGaN quantum well layers and green light GaN quantum barrier layers; the blue light multi-quantum well layer comprises periodically and alternately stacked blue light InGaN quantum well layers and blue light GaN quantum barrier layers; and the blue light multi-coupling well layer comprises periodically and alternately stacked blue light InGaN coupling well layers and blue light InGaN coupling barrier layers, wherein the blue light InGaN coupling barrier layer is a Zn and Si co-doped InGaN layer with a thickness of 1nm-6nm. According to the application, the hole concentration distribution in the multi-quantum well light-emitting layer is good in consistency, and the blue-green dual-band LED is high in light efficiency and good in color rendering performance.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a blue-green dual-band LED epitaxial wafer and its preparation method, and a blue-green dual-band LED. Background Technology

[0002] Currently, there are two types of LED backlight sources used in displays: RGB LEDs and white LEDs. RGB LEDs are made by packaging blue, green, and red LED chips together, while white LEDs produce white light by exciting phosphors with LED chips and mixing the light. For example, a blue LED chip can excite green and red phosphors to emit white light, or a blue LED chip can excite yellow phosphors to emit white light. Among these, RGB LED backlight sources offer the best display effect but are more expensive. White LEDs require phosphors, and the choice of phosphors has a significant impact on the color gamut. Furthermore, the uniformity of the phosphor mixture is difficult to control, leading to problems such as poor light uniformity, poor color consistency, and less than ideal color rendering. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a blue-green dual-band LED epitaxial wafer and its preparation method, and a blue-green dual-band LED. A single LED chip can simultaneously excite light sources in both blue and green bands, and the hole concentration distribution in the multi-quantum well light-emitting layer is highly consistent. The blue-green dual-band LED has high luminous efficacy and good color rendering performance.

[0004] To address the aforementioned issues, this invention discloses a blue-green dual-band LED epitaxial wafer, comprising a substrate, and a buffer layer, an N-type semiconductor layer, a low-temperature stress relief layer, a multi-quantum-well light-emitting layer, an electron blocking layer, and a P-type semiconductor layer sequentially stacked on the substrate. The multi-quantum-well light-emitting layer includes a green multi-quantum-well layer, a blue multi-quantum-well layer, and a blue multi-coupling-well layer stacked sequentially. The green light multi-quantum well layer comprises periodically alternating layers of green InGaN quantum well layers and green GaN quantum barrier layers; the blue light multi-quantum well layer comprises periodically alternating layers of blue InGaN quantum well layers and blue GaN quantum barrier layers; the blue light multi-coupled well layer comprises periodically alternating layers of blue InGaN coupled well layers and blue InGaN coupled barrier layers, wherein the blue InGaN coupled barrier layer is a Zn and Si co-doped InGaN layer with a thickness of 1 nm to 6 nm.

[0005] As an improvement to the above technical solution, when growing the blue InGaN coupling barrier layer, a Zn source and a Si source are introduced for co-doping, the growth temperature is 720℃~980℃, and the growth pressure is 30Torr~360Torr. The Si doping concentration of the blue InGaN coupling barrier layer is 1.25 × 10⁻⁶. 17 / cm 3 ~8.67×10 17 / cm 3 The flow rate into the Zn source is 1 sccm to 50 sccm.

[0006] As an improvement to the above technical solution, the number of cycles in which the blue light multi-coupled trap layers are alternately stacked is 1 to 8; The blue light InGaN coupling well layer is an undoped InGaN layer with an In composition ratio of 0.03~0.19 and a thickness of 1nm~6nm; The In composition ratio of the blue InGaN coupling barrier layer is 0.002~0.09.

[0007] As an improvement to the above technical solution, the number of cycles in which the green light multi-quantum well layers are alternately stacked is 2 to 12; The green InGaN quantum well layer is an undoped InGaN layer with an In composition ratio of 0.22~0.28 and a thickness of 2nm~5nm; The green GaN quantum barrier layer is a Si-doped GaN layer with a thickness of 5nm~16nm and a Si doping concentration of 1.25×10⁻⁶. 17 / cm 3 ~8.67×10 17 / cm 3 .

[0008] As an improvement to the above technical solution, the number of cycles in which the blue light multi-quantum well layers are alternately stacked is 3 to 15; The blue light InGaN quantum well layer is an undoped InGaN layer with an In composition ratio of 0.03~0.19 and a thickness of 2nm~5nm; The blue light GaN quantum barrier layer is a Si-doped GaN layer with a thickness of 5nm~16nm and a Si doping concentration of 1.25×10⁻⁶. 17 / cm 3 ~8.67×10 17 / cm 3 .

[0009] As an improvement to the above technical solution, the emission wavelength of the green light multi-quantum well layer is λ1, the emission wavelength of the blue light multi-quantum well layer is λ2, and the emission wavelength of the blue light multi-coupled well layer is λ3, where λ1 > λ2 and λ2 = λ3.

[0010] Accordingly, the present invention also discloses a method for preparing a blue-green dual-band LED epitaxial wafer, which includes the following steps: A substrate is provided on which a buffer layer, an N-type semiconductor layer, a low-temperature stress relief layer, a multi-quantum-well light-emitting layer, an electron blocking layer and a P-type semiconductor layer are sequentially grown. The multi-quantum-well light-emitting layer includes a green multi-quantum-well layer, a blue multi-quantum-well layer, and a blue multi-coupling-well layer stacked sequentially. The green light multi-quantum well layer comprises periodically alternating layers of green InGaN quantum well layers and green GaN quantum barrier layers; the blue light multi-quantum well layer comprises periodically alternating layers of blue InGaN quantum well layers and blue GaN quantum barrier layers; the blue light multi-coupled well layer comprises periodically alternating layers of blue InGaN coupled well layers and blue InGaN coupled barrier layers, wherein the blue InGaN coupled barrier layer is a Zn and Si co-doped InGaN layer with a thickness of 1 nm to 6 nm.

[0011] As an improvement to the above technical solution, the growth temperature of the blue InGaN coupling well layer is 660℃~950℃, and the growth pressure is 30Torr~360Torr. The growth temperature of the blue light InGaN coupling barrier layer is 720℃~980℃, and the growth pressure is 30Torr~360Torr. When growing the blue light InGaN coupling barrier layer, a Zn source and a Si source are introduced for co-doping. The Zn source is DMZn or DEZn, and the flow rate is 1sccm~50sccm.

[0012] As an improvement to the above technical solution, the growth temperature of the green InGaN quantum well layer is 620℃~950℃ and the growth pressure is 30Torr~360Torr, and the growth temperature of the green GaN quantum barrier layer is 720℃~980℃ and the growth pressure is 30Torr~360Torr. The growth temperature of the blue InGaN quantum well layer is 660℃~950℃, and the growth pressure is 30Torr~360Torr. The growth temperature of the blue GaN quantum barrier layer is 720℃~980℃, and the growth pressure is 30Torr~360Torr.

[0013] Accordingly, the present invention also discloses a blue-green dual-band LED, comprising the above-mentioned blue-green dual-band LED epitaxial wafer or the blue-green dual-band LED epitaxial wafer prepared by the above-mentioned preparation method.

[0014] Implementing this invention has the following beneficial effects: 1. The blue-green dual-band LED epitaxial wafer provided by the present invention has a multi-quantum well light-emitting layer comprising a green multi-quantum well layer, a blue multi-quantum well layer and a blue multi-coupling well layer stacked sequentially. A single LED chip can simultaneously excite light sources in both blue and green bands. When applied to RGB LED backlight sources, it can reduce costs. When applied to white LED backlight sources, it can reduce the use of phosphors.

[0015] 2. In the blue-green dual-band LED epitaxial wafer provided by the present invention, the blue light multi-coupled well layer near the P-type semiconductor layer includes periodically alternating layers of blue light InGaN coupled well layers and blue light InGaN coupled barrier layers. The blue light InGaN coupled barrier layer is a thin barrier layer structure with a thickness of only 1nm~6nm. The wave function of holes is coupled in the blue light multi-coupled well layer, which greatly improves the transport capability of holes to the well layer near the N-type semiconductor layer. At the same time, the low bandgap InGaN material further improves the hole injection efficiency of the P-type semiconductor layer, so that the hole concentration is uniformly distributed in each well layer of the multi-quantum well light-emitting layer, thereby improving the luminous efficacy and color rendering performance of the blue-green dual-band light-emitting diode.

[0016] 3. In the blue-green dual-band LED epitaxial wafer provided by this invention, the blue InGaN coupling barrier layer is co-doped with Zn and Si. The defect passivation effect of Zn is used to improve the crystal quality and significantly reduce the non-radiative recombination rate, thereby improving the luminous efficiency of Micro-LED at low operating current density. At the same time, the doping of Zn introduces holes into the valence band of the blue InGaN coupling barrier layer, which can effectively reduce the potential barrier of the blue InGaN coupling barrier layer, making it easier for holes to be injected from the P-type semiconductor layer into the multi-quantum well light-emitting layer, further improving the hole injection efficiency of the P-type semiconductor layer, and making the hole concentration distribution in each well layer of the multi-quantum well light-emitting layer more uniform, thereby further improving the luminous efficacy and color rendering performance of the blue-green dual-band LED provided by this invention. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the blue-green dual-band LED epitaxial wafer provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the multi-quantum-well light-emitting layer in the blue-green dual-band LED epitaxial wafer provided in an embodiment of the present invention; Figure 3 This is a flowchart of the method for preparing a blue-green dual-band LED epitaxial wafer according to an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below.

[0019] like Figure 1 and Figure 2As shown, the present invention provides a blue-green dual-band LED epitaxial wafer, including a substrate 100, and a buffer layer 200, an N-type semiconductor layer 300, a low-temperature stress relief layer 400, a multi-quantum well light-emitting layer 500, an electron blocking layer 600 and a P-type semiconductor layer 700 sequentially stacked on the substrate 100.

[0020] The multi-quantum-well light-emitting layer 500 includes a green multi-quantum-well layer 510, a blue multi-quantum-well layer 520 and a blue multi-coupling-well layer 530 stacked sequentially.

[0021] By sequentially stacking a green quantum well layer 510, a blue quantum well layer 520, and a blue multi-coupling well layer 530, a single LED chip can simultaneously excite light sources in both blue and green wavelengths. This can reduce costs when applied to RGB LED backlight sources and reduce the use of phosphors when applied to white LED backlight sources.

[0022] The green light multi-quantum well layer 510 includes a periodically alternating stacked green light InGaN quantum well layer 511 and a green light GaN quantum barrier layer 512; the blue light multi-quantum well layer 520 includes a periodically alternating stacked blue light InGaN quantum well layer 521 and a blue light GaN quantum barrier layer 522; the blue light multi-coupled well layer 530 includes a periodically alternating stacked blue light InGaN coupled well layer 531 and a blue light InGaN coupled barrier layer 532, wherein the blue light InGaN coupled barrier layer 532 is a Zn and Si co-doped InGaN layer with a thickness of 1 nm to 6 nm.

[0023] In the multi-quantum-well light-emitting layer 500, the layer closest to the P-type semiconductor layer 700 is the blue light multi-coupled-well layer 530. Specifically, the blue light multi-coupled-well layer 530 includes periodically alternating layers of blue light InGaN coupled-well layer 531 and blue light InGaN coupled-barrier layer 532. The thickness of the blue light InGaN coupled-barrier layer 532 is only 1nm~6nm, which is a thin barrier layer structure. The wave function of holes is coupled in the blue light multi-coupled-well layer, which greatly improves the transport capability of holes to the well layer close to the N-type semiconductor layer 300. At the same time, the low bandgap InGaN material further improves the hole injection efficiency of the P-type semiconductor layer 700. Furthermore, the blue InGaN coupling barrier layer 532 is co-doped with Zn and Si. The defect passivation effect of Zn improves crystal quality and significantly reduces the non-radiative recombination rate, thereby increasing the luminous efficiency of the Micro-LED at low operating current densities. Simultaneously, the Zn doping introduces holes into the valence band of the blue InGaN coupling barrier layer 532, effectively lowering the barrier and facilitating hole injection from the P-type semiconductor layer 700 into the multi-quantum-well emitting layer 500, further improving the hole injection efficiency of the P-type semiconductor layer 700. By setting the blue multi-coupling-well layer 530, the radiative recombination rate of carriers in the multi-quantum-well emitting layer 500 is increased, leading to improved luminous efficiency. In addition, the uniformity of hole concentration distribution in each well layer of the multi-quantum-well emitting layer 500 is improved. Consequently, the consistency of green and blue light intensity is enhanced, improving the light emission uniformity of the blue-green dual-band LED and reducing spectral deviation, thereby suppressing color temperature shift and improving color tone consistency. In summary, this invention can improve the luminous efficacy and color rendering performance of blue-green dual-band light-emitting diodes.

[0024] In one embodiment, during the growth of the blue InGaN coupling barrier layer 532, a Zn source and a Si source are introduced for co-doping. The growth temperature is 720℃~980℃, and the growth pressure is 30 Torr~360 Torr. The Si doping concentration of the blue InGaN coupling barrier layer 532 is 1.25 × 10⁻⁶. 17 / cm 3 ~8.67×10 17 / cm 3 An example is 1.25 × 10 17 / cm 3 2.5×10 17 / cm 3 5×10 17 / cm 3 6.5×10 17 / cm 3 7×10 17 / cm 3 Or 8.67×10 17 / cm 3However, this is not limited to the above; the flow rate of the Zn source is 1 sccm to 50 sccm, exemplarily 1 sccm, 5 sccm, 10 sccm, 20 sccm, 35 sccm, or 50 sccm, but not limited to these. It is understood that the Zn doping concentration is affected by the combined effects of flow rate, growth temperature, and growth pressure. This invention limits the Zn doping concentration by defining the growth temperature, growth pressure, and the flow rate of the Zn source. Optionally, the Zn source is DMZn or DEZn, without specific limitation here.

[0025] In one embodiment, the number of alternating stacked periods of the blue light multi-coupled well layer 530 is 1 to 8, exemplarily 1, 2, 3, 4, 5, 6, 7, or 8. The blue light InGaN coupling well layer 531 is an undoped InGaN layer with an In composition ratio of 0.03 to 0.19, exemplarily 0.03, 0.05, 0.09, 0.1, 0.15, or 0.19, but not limited thereto. The thickness of the blue light InGaN coupling well layer 531 is 1 nm to 6 nm, exemplarily 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, or 6 nm, but not limited thereto. The In composition ratio of the blue light InGaN coupling barrier layer 532 is 0.002 to 0.09, exemplarily 0.002, 0.008, 0.01, 0.04, 0.06, or 0.09, but not limited thereto. The thickness of the blue InGaN coupling barrier layer 532 is 1nm to 6nm, exemplarily 1nm, 2nm, 3nm, 4nm, 5nm, or 6nm, but not limited to these. In the blue multi-coupled well layer 530, both the blue InGaN coupling well layer 531 and the blue InGaN coupling barrier layer 532 are made of InGaN. InGaN material has a low bandgap. The blue InGaN coupling well layer 531 and the blue InGaN coupling barrier layer 532 are periodically and alternately stacked to further improve the hole injection efficiency of the P-type semiconductor layer 700.

[0026] The green light multi-quantum well layer 510 is used to emit green light. In one embodiment, the number of alternating stacked periods of the green light multi-quantum well layer 510 is 2 to 12, exemplarily 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12. The green light InGaN quantum well layer 511 is an undoped InGaN layer with an In composition ratio of 0.22 to 0.28, exemplarily 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, or 0.28, but not limited thereto. The thickness of the green light InGaN quantum well layer 511 is 2 nm to 5 nm, exemplarily 2 nm, 3 nm, 4 nm, or 5 nm, but not limited thereto. The thickness of the green light GaN quantum barrier layer 512 is 5 nm to 16 nm, exemplarily 5 nm, 8 nm, 10 nm, 14 nm, 15 nm, or 16 nm, but not limited thereto. The green GaN quantum barrier layer 512 is a Si-doped GaN layer with a Si doping concentration of 1.25 × 10⁻⁶. 17 / cm 3 ~8.67×10 17 / cm 3 An example is 1.25 × 10 17 / cm 3 2.5×10 17 / cm 3 5×10 17 / cm 3 6.5×10 17 / cm 3 7×10 17 / cm 3 Or 8.67×10 17 / cm 3 However, this is not the only benefit. Si doping of the green GaN quantum barrier layer 512 improves the interface quality and In composition fluctuations of the green multi-quantum-well layer 510, and under the action of an applied positive current, it shields the polarization electric field to a greater extent, thereby effectively improving the radiative recombination efficiency of charge carriers.

[0027] The blue light multi-quantum well layer 520 is used to emit blue light. In one embodiment, the number of alternating stacked periods of the blue light multi-quantum well layer 520 is 3 to 15, exemplarily 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15. The blue light InGaN quantum well layer 521 is an undoped InGaN layer with an In composition ratio of 0.03 to 0.19, exemplarily 0.03, 0.05, 0.09, 0.1, 0.15, or 0.19, but not limited thereto. The thickness of the blue light InGaN quantum well layer 521 is 2 nm to 5 nm, exemplarily 2 nm, 3 nm, 4 nm, or 5 nm, but not limited thereto. The thickness of the blue light GaN quantum barrier layer 522 is 5 nm to 16 nm, exemplarily 5 nm, 8 nm, 10 nm, 14 nm, 15 nm, or 16 nm, but not limited thereto. The blue GaN quantum barrier layer 522 is a Si-doped GaN layer with a Si doping concentration of 1.25 × 10⁻⁶. 17 / cm 3 ~8.67×10 17 / cm 3 An example is 1.25 × 10 17 / cm 3 2.5×10 17 / cm 3 5×10 17 / cm 3 6.5×10 17 / cm 3 7×10 17 / cm 3 Or 8.67×10 17 / cm 3 However, this is not the only benefit. Si doping of the blue GaN quantum barrier layer 522 improves the interface quality and In composition fluctuations of the blue multi-quantum-well layer 520, and under the action of an applied positive current, it shields the polarization electric field to a greater extent, thereby effectively improving the radiative recombination efficiency of charge carriers.

[0028] Because the In composition of the blue InGaN quantum well layer 521 in the blue multi-quantum well layer 520 is low, carriers are less likely to recombine and generate photons in the blue multi-quantum well layer 520, thus affecting the brightness of the blue light. In one embodiment, the emission wavelength of the green multi-quantum well layer 510 is λ1, the emission wavelength of the blue multi-quantum well layer 520 is λ2, and the emission wavelength of the blue multi-coupled well layer 530 is λ3, where λ1 > λ2 and λ2 = λ3. The blue multi-quantum well layer 520 and the blue multi-coupled well layer 530 have the same emission wavelength, which is used to enhance the luminous intensity of the blue light.

[0029] It is understood that the green InGaN quantum well layer 511, the green GaN quantum barrier layer 512, the blue InGaN quantum well layer 521, the blue GaN quantum barrier layer 522, and the blue InGaN coupling well layer 531 can all be single-layer or multi-layer structures, and no specific limitation is made here.

[0030] Besides the multi-quantum-well light-emitting layer 500, the other features of the layered structure of the present invention are as follows: The substrate 100 can be one of a sapphire substrate, a SiO2 sapphire composite substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, or a zinc oxide substrate. In one embodiment, the substrate 100 is selected as a sapphire substrate.

[0031] The buffer layer 200 can be an AlN buffer layer and / or an AlGaN buffer layer. In one embodiment, the buffer layer 200 is an AlN buffer layer with a thickness of 20 nm to 200 nm.

[0032] The N-type semiconductor layer 300 includes an undoped GaN layer and an N-type GaN layer. The thickness of the undoped GaN layer is 1 μm to 5 μm, and the thickness of the N-type GaN layer is 2 μm to 3 μm. The Si doping concentration is 1 × 10⁻⁶. 19 / cm 3 ~5×10 19 / cm 3 .

[0033] The low-temperature stress relief layer 400 may include periodically alternating layers of InGaN and GaN stress relief layers, with 2 to 10 alternating stacking periods. The InGaN stress relief layer has a thickness of 1 nm to 3 nm, and the GaN stress relief layer has a thickness of 15 nm to 30 nm. The growth temperature of the low-temperature stress relief layer 400 is 800℃ to 900℃.

[0034] The electron blocking layer 600 can be an AlGaN electron blocking layer with a thickness of 10nm~100nm and an Al composition ratio of 0.4~0.8%.

[0035] The P-type semiconductor layer 700 can be a P-type GaN layer with a thickness of 10nm~50nm and a Mg doping concentration of 1×10⁻⁶. 19 / cm 3 ~5×10 20 / cm 3 .

[0036] Correspondingly, such as Figure 3 As shown, this invention also discloses a method for preparing a blue-green dual-band LED epitaxial wafer, which includes the following steps: S1. Provide a substrate 100.

[0037] In one embodiment, the substrate 100 is selected as a sapphire substrate.

[0038] S2. A buffer layer 200, an N-type semiconductor layer 300, a low-temperature stress relief layer 400, a multi-quantum well light-emitting layer 500, an electron blocking layer 600, and a P-type semiconductor layer 700 are sequentially grown on the substrate 100.

[0039] It is understandable that layered structures can be grown by MOCVD, MBE, PVD, or VPE, but are not limited to these methods.

[0040] In one embodiment, the fabrication of the multi-quantum-well light-emitting layer 500 includes: S21. Fabrication of green light multi-quantum well layer 510.

[0041] In one embodiment, MOCVD growth is employed, with the reaction chamber temperature controlled at 620°C~950°C and the pressure at 30 Torr~360 Torr, and In, Ga, and N sources introduced to grow a green InGaN quantum well layer 511; the reaction chamber temperature is controlled at 720°C~980°C and the growth pressure at 30 Torr~360 Torr, and Ga, N, and Si sources introduced to grow a green GaN quantum barrier layer 512; the green InGaN quantum well layer 511 and the green GaN quantum barrier layer 512 are repeatedly stacked and periodically grown.

[0042] S22, Fabrication of blue light multi-quantum well layer 520.

[0043] In one embodiment, MOCVD growth is employed, with the reaction chamber temperature controlled at 660°C~950°C and the pressure at 30 Torr~360 Torr, and In, Ga, and N sources introduced to grow a blue InGaN quantum well layer 521; the reaction chamber temperature is controlled at 720°C~980°C and the growth pressure at 30 Torr~360 Torr, and Ga, N, and Si sources introduced to grow a blue GaN quantum barrier layer 522; the blue InGaN quantum well layer 521 and the blue GaN quantum barrier layer 522 are repeatedly stacked and periodically grown.

[0044] S23. Fabrication of blue light multi-coupled trap layer 530.

[0045] In one embodiment, MOCVD growth is employed, with the reaction chamber temperature controlled at 660°C~950°C and the pressure at 30 Torr~360 Torr, and In, Ga, and N sources introduced to grow a blue InGaN coupling well layer 531; the reaction chamber temperature is controlled at 720°C~980°C and the growth pressure at 30 Torr~360 Torr, and In, Ga, N, Si, and Zn sources introduced to grow a blue InGaN coupling barrier layer 532; the blue InGaN coupling well layer 531 and the blue InGaN coupling barrier layer 532 are repeatedly stacked and periodically grown.

[0046] The present invention will be further described below with reference to specific embodiments: Example 1 This embodiment provides a blue-green dual-band LED epitaxial wafer, including a substrate and a buffer layer, an N-type semiconductor layer, a low-temperature stress relief layer, a multi-quantum-well light-emitting layer, an electron blocking layer, and a P-type semiconductor layer sequentially stacked on the substrate. The multi-quantum-well light-emitting layer includes a green multi-quantum-well layer, a blue multi-quantum-well layer, and a blue multi-coupling-well layer sequentially stacked.

[0047] The green-light multi-quantum-well layer comprises periodically alternating layers of green InGaN quantum wells and green GaN quantum barriers, with a period of 5 alternations. The green InGaN quantum well layer has an In composition of 0.25%, a thickness of 3 nm, a growth temperature of 780 °C, and a growth pressure of 250 Torr. The green GaN quantum barrier layer is a Si-doped GaN layer with a Si doping concentration of 5 × 10⁻⁶. 17 / cm 3 The thickness is 10 nm, the growth temperature is 850℃, and the growth pressure is 250 Torr.

[0048] The blue-light multi-quantum-well layer comprises periodically alternating layers of blue InGaN quantum wells and blue GaN quantum barriers, with a period of 6 alternations. The InGaN quantum well layer has an In composition of 0.15%, a thickness of 3 nm, a growth temperature of 800℃, and a growth pressure of 250 Torr. The blue GaN quantum barrier layer is a Si-doped GaN layer with a Si doping concentration of 5 × 10⁻⁶. 17 / cm 3 The thickness is 10 nm, the growth temperature is 850℃, and the growth pressure is 250 Torr.

[0049] The blue-light multi-coupled-well layer comprises periodically alternating layers of blue-light InGaN coupled-well layers and blue-light InGaN coupled-barrier layers, with a period of 3 alternations. The blue-light InGaN coupled-well layer has an In composition of 0.03%, a thickness of 5 nm, a growth temperature of 800℃, and a growth pressure of 250 Torr. The blue-light InGaN coupled-barrier layer is a Zn and Si co-doped InGaN layer with an In composition of 0.002% and a Si doping concentration of 8.67 × 10⁻⁶. 17 / cm 3 The thickness is 1 nm, the growth temperature of the blue InGaN coupling barrier layer is 800℃, the growth pressure is 200 Torr, and the flow rate of Zn introduced during growth is 50 sccm.

[0050] The emission wavelength of the green multi-quantum well layer is λ1, the emission wavelength of the blue multi-quantum well layer is λ2, and the emission wavelength of the blue multi-coupled well layer is λ3, where λ1 > λ2 and λ2 = λ3.

[0051] Example 2 This embodiment provides a blue-green dual-band LED epitaxial wafer, which differs from Embodiment 1 in that the In composition ratio of the blue InGaN coupling barrier layer is 0.09, and the Si doping concentration is 1.25 × 10⁻⁶. 17 / cm 3 The thickness is 6nm, and the flow rate of Zn introduced during growth is 1sccm.

[0052] Everything else is the same as in Example 1.

[0053] Example 3 This embodiment provides a blue-green dual-band LED epitaxial wafer, which differs from Embodiment 1 in that the In composition ratio of the blue InGaN coupling barrier layer is 0.05, and the Si doping concentration is 5×10⁻⁶. 17 / cm 3 The thickness is 3nm, and the Zn flow rate during growth is 30sccm.

[0054] Everything else is the same as in Example 1.

[0055] Comparative Example 1 This comparative example provides a blue-green dual-band LED epitaxial wafer, which differs from Example 1 in that the multi-quantum well light-emitting layer includes a green multi-quantum well layer and a blue multi-quantum well layer stacked sequentially, that is, it does not include a blue multi-coupling well layer.

[0056] Everything else is the same as in Example 1.

[0057] Comparative Example 2 This comparative example provides a blue-green dual-band LED epitaxial wafer, which differs from Example 1 in that, in the blue light multi-coupled well layer, the blue light InGaN coupling barrier layer is a Si-doped InGaN layer with an In composition ratio of 0.02 and a Si doping concentration of 5 × 10⁻⁶. 17 / cm 3 The thickness is 10nm.

[0058] Everything else is the same as in Example 1.

[0059] The blue-green dual-band LED epitaxial wafers prepared in Examples 1 to 3, Comparative Example 1 and Comparative Example 2 were fabricated into 10mil×24mil chips using the same chip process conditions. 300 chips were randomly selected from each example for performance testing.

[0060] (1) Luminous efficiency improvement rate: On the same LED spot tester, the luminous efficiency improvement rate of Examples 1 to 3 and Comparative Example 2 relative to Comparative Example 1 was measured at a current of 60mA and the current improvement rate was calculated.

[0061] (2) Wavelength uniformity: The peak wavelengths of the chips prepared in Examples 1 to 3, Comparative Example 1 and Comparative Example 2 were measured by PL spectroscopy, and the standard deviation of the peak wavelength (WD_STD) of each chip was calculated.

[0062] (3) Color rendering effect: The color rendering index and fidelity of the chips prepared in Examples 1 to 3, Comparative Example 1 and Comparative Example 2 were tested according to ANSI / IES TM-30-20.

[0063] The specific results are shown in Table 1: Table 1 Performance test results of the examples and comparative examples

[0064] The above description is a preferred embodiment of the invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A blue-green dual-band LED epitaxial wafer, characterized in that, It includes a substrate, and a buffer layer, an N-type semiconductor layer, a low-temperature stress relief layer, a multi-quantum-well light-emitting layer, an electron blocking layer and a P-type semiconductor layer sequentially stacked on the substrate; The multi-quantum-well light-emitting layer includes a green multi-quantum-well layer, a blue multi-quantum-well layer, and a blue multi-coupling-well layer stacked sequentially. The green light multi-quantum well layer comprises periodically alternating layers of green InGaN quantum well layers and green GaN quantum barrier layers; the blue light multi-quantum well layer comprises periodically alternating layers of blue InGaN quantum well layers and blue GaN quantum barrier layers; the blue light multi-coupled well layer comprises periodically alternating layers of blue InGaN coupled well layers and blue InGaN coupled barrier layers, wherein the blue InGaN coupled barrier layer is a Zn and Si co-doped InGaN layer with a thickness of 1 nm to 6 nm.

2. The blue-green dual-band LED epitaxial wafer as described in claim 1, characterized in that, When growing the blue light InGaN coupling barrier layer, Zn source and Si source are introduced for co-doping, the growth temperature is 720℃~980℃, and the growth pressure is 30Torr~360Torr. The Si doping concentration of the blue InGaN coupling barrier layer is 1.25 × 10⁻⁶. 17 / cm 3 ~8.67×10 17 / cm 3 ; The flow rate introduced into the Zn source is 1 sccm to 50 sccm.

3. The blue-green dual-band LED epitaxial wafer as described in claim 1, characterized in that, The number of alternating stacks of the blue light multi-coupled trap layers is 1 to 8; The blue light InGaN coupling well layer is an undoped InGaN layer with an In composition ratio of 0.03~0.19 and a thickness of 1nm~6nm; The In composition ratio of the blue InGaN coupling barrier layer is 0.002~0.

09.

4. The blue-green dual-band LED epitaxial wafer as described in claim 1, characterized in that, The number of alternating stacks of the green light multi-quantum well layers is 2 to 12; The green InGaN quantum well layer is an undoped InGaN layer with an In composition ratio of 0.22~0.28 and a thickness of 2nm~5nm; The green GaN quantum barrier layer is a Si-doped GaN layer with a thickness of 5nm~16nm and a Si doping concentration of 1.25×10⁻⁶. 17 / cm 3 ~8.67×10 17 / cm 3 .

5. The blue-green dual-band LED epitaxial wafer as described in claim 1, characterized in that, The number of alternating stacks of the blue light multi-quantum well layers is 3 to 15; The blue light InGaN quantum well layer is an undoped InGaN layer with an In composition ratio of 0.03~0.19 and a thickness of 2nm~5nm; The blue light GaN quantum barrier layer is a Si-doped GaN layer with a thickness of 5nm~16nm and a Si doping concentration of 1.25×10⁻⁶. 17 / cm 3 ~8.67×10 17 / cm 3 .

6. The blue-green dual-band LED epitaxial wafer as described in claim 1, characterized in that, The emission wavelength of the green multi-quantum well layer is λ1, the emission wavelength of the blue multi-quantum well layer is λ2, and the emission wavelength of the blue multi-coupled well layer is λ3, where λ1 > λ2 and λ2 = λ3.

7. A method for fabricating a blue-green dual-band LED epitaxial wafer, used to fabricate the blue-green dual-band LED epitaxial wafer as described in any one of claims 1 to 6, characterized in that, Includes the following steps: A substrate is provided on which a buffer layer, an N-type semiconductor layer, a low-temperature stress relief layer, a multi-quantum-well light-emitting layer, an electron blocking layer and a P-type semiconductor layer are sequentially grown. The multi-quantum-well light-emitting layer includes a green multi-quantum-well layer, a blue multi-quantum-well layer, and a blue multi-coupling-well layer stacked sequentially. The green light multi-quantum well layer comprises periodically alternating layers of green InGaN quantum well layers and green GaN quantum barrier layers; the blue light multi-quantum well layer comprises periodically alternating layers of blue InGaN quantum well layers and blue GaN quantum barrier layers; the blue light multi-coupled well layer comprises periodically alternating layers of blue InGaN coupled well layers and blue InGaN coupled barrier layers, wherein the blue InGaN coupled barrier layer is a Zn and Si co-doped InGaN layer with a thickness of 1 nm to 6 nm.

8. The method for preparing a blue-green dual-band LED epitaxial wafer as described in claim 7, characterized in that, The growth temperature of the blue InGaN coupling well layer is 660℃~950℃, and the growth pressure is 30Torr~360Torr. The growth temperature of the blue light InGaN coupling barrier layer is 720℃~980℃, and the growth pressure is 30Torr~360Torr. When growing the blue light InGaN coupling barrier layer, a Zn source and a Si source are introduced for co-doping. The Zn source is DMZn or DEZn, and the flow rate is 1sccm~50sccm.

9. The method for preparing a blue-green dual-band LED epitaxial wafer as described in claim 7, characterized in that, The growth temperature of the green InGaN quantum well layer is 620℃~950℃, and the growth pressure is 30Torr~360Torr. The growth temperature of the green GaN quantum barrier layer is 720℃~980℃, and the growth pressure is 30Torr~360Torr. The growth temperature of the blue InGaN quantum well layer is 660℃~950℃, and the growth pressure is 30Torr~360Torr. The growth temperature of the blue GaN quantum barrier layer is 720℃~980℃, and the growth pressure is 30Torr~360Torr.

10. A blue-green dual-band LED, characterized in that, This includes the blue-green dual-band LED epitaxial wafer as described in any one of claims 1 to 6, or the blue-green dual-band LED epitaxial wafer prepared by the preparation method described in any one of claims 7 to 9.

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