Light emitting diode with improved color purity and preparation method thereof

Abstract

The invention provides a light emitting diode with improved color purity and a preparation method thereof, and belongs to the technical field of photoelectron manufacturing. The light-emitting diode comprises a first semiconductor layer, a first light-emitting layer, a second light-emitting layer and a second semiconductor layer which are sequentially stacked, the first light-emitting layer is a green light-emitting layer, the second light-emitting layer is a blue light-emitting layer, and the ratio of the light-emitting intensity of the first light-emitting layer to the light-emitting intensity of the second light-emitting layer ranges from 2: 10 to 4.8: 10. According to the embodiment of the invention, the color gamut value of the light-emitting diode can be improved, the color purity of the light-emitting diode can be improved, and the light-emitting effect is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of optoelectronic manufacturing technologies, and particularly to a light-emitting diode for improving color purity and a preparation method thereof. Background Art

[0002] As a highly influential new product in the optoelectronic industry, a light-emitting diode (LED) has the characteristics of small size, long service life, rich and colorful colors, low energy consumption, etc., and is widely used in the fields of lighting, display screens, signal lights, backlights, toys, etc.

[0003] In related technologies, a light-emitting diode generally includes a blue light epitaxial wafer and phosphors of various colors. The light emitted by the epitaxial wafer and the light excited by the phosphors are synthesized into lights of various colors to increase the color gamut value of the light-emitting diode.

[0004] However, although the synthesis of lights of different colors by the phosphor and the epitaxial wafer can expand the color range of the light emitted by the light-emitting diode, the purity of the color of the light emitted by the light-emitting diode is poor, resulting in the light-emitting color of the light-emitting diode not being bright enough and affecting the light-emitting effect. Summary of the Invention

[0005] Embodiments of the present disclosure provide a light-emitting diode for improving color purity and a preparation method thereof, which can not only improve the color gamut value of the light-emitting diode, but also improve the color purity of the light-emitting diode and the light-emitting effect. The technical solutions are as follows:

[0006] On the one hand, embodiments of the present disclosure provide a light-emitting diode, which includes a first semiconductor layer, a first light-emitting layer, a second light-emitting layer, and a second semiconductor layer stacked in sequence. The first light-emitting layer is a green light-emitting layer, the second light-emitting layer is a blue light-emitting layer, and the ratio of the light-emitting intensity of the first light-emitting layer to the light-emitting intensity of the second light-emitting layer is 2:10 to 4.8:10.

[0007] Optionally, the ratio of the light-emitting intensity of the first light-emitting layer to the light-emitting intensity of the second light-emitting layer is 3.6:10 to 4.8:10.

[0008] Optionally, the ratio of the light-emitting intensity of the first light-emitting layer to the light-emitting intensity of the second light-emitting layer is 3.6:10 to 4:10.

[0009] Optionally, the ratio of the light-emitting intensity of the first light-emitting layer to the light-emitting intensity of the second light-emitting layer is 4:10 to 4.8:10.

[0010] Optionally, the first light-emitting layer includes 1 to 10 pairs of quantum barrier layers and quantum well layers stacked alternately, and the second light-emitting layer includes 5 to 50 pairs of quantum barrier layers and quantum well layers stacked alternately.

[0011] Optionally, the first light-emitting layer includes 3 pairs of quantum barrier layers and quantum well layers stacked alternately, and the second light-emitting layer includes 10 pairs of quantum barrier layers and quantum well layers stacked alternately; alternatively, the first light-emitting layer includes 6 pairs of quantum barrier layers and quantum well layers stacked alternately, and the second light-emitting layer includes 9 pairs of quantum barrier layers and quantum well layers stacked alternately.

[0012] Optionally, the thickness of the quantum well layer of the first light-emitting layer is 2 nm to 5 nm, and the thickness of the quantum barrier layer of the first light-emitting layer is 10 nm to 150 nm; the thickness of the quantum well layer of the second light-emitting layer is 2 nm to 5 nm, and the thickness of the quantum barrier layer of the second light-emitting layer is 8 nm to 14 nm.

[0013] On the other hand, an embodiment of the present disclosure provides a method for manufacturing a light-emitting diode. The manufacturing method includes: forming a first semiconductor layer on a substrate; sequentially forming a first light-emitting layer and a second light-emitting layer on the surface of the first semiconductor layer. The first light-emitting layer is a green light-emitting layer, and the second light-emitting layer is a blue light-emitting layer, and the ratio of the light-emitting intensity of the first light-emitting layer to the light-emitting intensity of the second light-emitting layer is 2:10 to 4.8:10; forming a second semiconductor layer on the surface of the second light-emitting layer.

[0014] Optionally, forming the first light-emitting layer on the first semiconductor layer includes: controlling the growth temperature to be 700 °C to 780 °C, the growth pressure to be 200 torr to 400 torr, controlling the rotation speed of the graphite disk to be 500 r / min to 1000 r / min, and growing the quantum well layer of the first light-emitting layer; controlling the growth temperature to be 850 °C to 1000 °C, the growth pressure to be 200 torr to 400 torr, controlling the rotation speed of the graphite disk to be 500 r / min to 1000 r / min, and growing the quantum barrier layer of the first light-emitting layer.

[0015] Optionally, forming the second light-emitting layer on the first light-emitting layer includes: controlling the growth temperature to be 780 °C to 850 °C, the growth pressure to be 150 torr to 300 torr, controlling the rotation speed of the graphite disk to be 500 r / min to 1000 r / min, and growing the quantum well layer of the second light-emitting layer; controlling the growth temperature to be 830 °C to 920 °C, the growth pressure to be 150 torr to 300 torr, controlling the rotation speed of the graphite disk to be 500 r / min to 1000 r / min, and growing the quantum barrier layer of the second light-emitting layer.

[0016] The beneficial effects brought by the technical solution provided by the embodiment of the present disclosure at least include:

[0017] The light-emitting diode provided by an embodiment of the present disclosure includes a first semiconductor layer, a first light-emitting layer, a second light-emitting layer, and a second semiconductor layer stacked in sequence. Among them, the first light-emitting layer is a green light-emitting layer, and the second light-emitting layer is a blue light-emitting layer. Compared with synthesizing light of different colors by using the light emitted by the light-emitting layer and the excitation of the phosphor, the embodiment of the present disclosure directly uses two light-emitting layers of different colors, and synthesizes the light of the required color by using the different colors of light emitted by the different light-emitting layers, which can also achieve the purpose of expanding the color range of the light emitted by the light-emitting diode to improve the color gamut. At the same time, since the phosphor is usually encapsulated on the epitaxial layer after the epitaxial layer is prepared, the distance between the phosphor and the light-emitting layer in the epitaxial layer is relatively far, which will affect the excitation energy received by the phosphor, resulting in a decrease in the luminous efficiency of the phosphor and poor color purity of the phosphor. In the embodiment of the present disclosure, two light-emitting layers of different colors are directly arranged in a stacked manner, and the light of the required color is synthesized by using the different colors of light emitted by the two light-emitting layers. Therefore, the problem of insufficiently bright emission color will not occur, and the color of the emitted light can be closer to the monochromatic light in the spectrum, improving the color purity of the light-emitting diode and the emission effect. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0019] Figure 1 is a schematic structural diagram of a light-emitting diode provided by an embodiment of the present disclosure;

[0020] Figure 2 is a spectrogram of a light-emitting diode provided by an embodiment of the present disclosure;

[0021] Figure 3 is a spectrogram of another light-emitting diode provided by an embodiment of the present disclosure;

[0022] Figure 4 is a flowchart of a method for manufacturing a light-emitting diode provided by an embodiment of the present disclosure.

[0023] The descriptions of the marks in the drawings are as follows:

[0024] 10. Substrate;

[0025] 20. First semiconductor layer;

[0026] 31. First light-emitting layer; 32. Second light-emitting layer;

[0027] 40. Second semiconductor layer; 41. Low-temperature p-type GaN layer; 42. Electron blocking layer; 43. High-temperature p-type GaN layer; 44. p-type contact layer;

[0028] 51. Buffer layer; 52. u-shaped GaN layer;

[0029] 61. Superlattice layer; 62. Pre-multi-quantum well layer. Detailed implementation manners

[0030] To make the objectives, technical solutions, and advantages of the present disclosure clearer, the following will further describe the embodiments of the present disclosure in detail with reference to the accompanying drawings.

[0031] Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the art to which the present disclosure pertains. The terms "first", "second", "third", and similar terms used in the specification and claims of the present patent application do not denote any order, quantity, or importance, but are only used to distinguish different components. Similarly, terms such as "a" or "one" do not denote a quantity limitation, but mean that there is at least one. The terms "comprising" or "including" and similar terms are intended to mean that the elements or items appearing before "comprising" or "including" cover the elements or items listed after "comprising" or "including" and their equivalents, and do not exclude other elements or items. The terms "connected" or "coupled" and similar terms are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right", "top", "bottom", etc. are only used to indicate relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationships may also change accordingly.

[0032] Figure 1 is a schematic structural diagram of a light-emitting diode provided by an embodiment of the present disclosure. As Figure 1 shown, the light-emitting diode includes a first semiconductor layer 20, a first light-emitting layer 31, a second light-emitting layer 32, and a second semiconductor layer 40 that are stacked in sequence. The first light-emitting layer 31 is a green light-emitting layer, and the second light-emitting layer 32 is a blue light-emitting layer.

[0033] Among them, the ratio of the light-emitting intensity of the first light-emitting layer 31 to the light-emitting intensity of the second light-emitting layer 32 is 2:10 to 4.8:10. In the embodiment of the present disclosure, the green light emitted by the first light-emitting layer and the blue light emitted by the second light-emitting layer are mixed to obtain cyan light, and the color depth of the cyan light will be different. Since the blue light intensity is relatively large, the component of blue light in the mixed color will be more prominent, and thus the obtained cyan light will be more biased towards the blue side of the cyan tone.

[0034] The light-emitting diode provided by the embodiment of the present disclosure includes a first semiconductor layer 20, a first light-emitting layer 31, a second light-emitting layer 32, and a second semiconductor layer 40 that are stacked in sequence. Among them, the first light-emitting layer 31 is a green light-emitting layer, and the second light-emitting layer 32 is a blue light-emitting layer. Compared with synthesizing light of different colors by using the light emission of the light-emitting layer and the excitation of the phosphor, the embodiment of the present disclosure directly uses two light-emitting layers of different colors, and synthesizes the light of the required color by using the different colors emitted by the different light-emitting layers, which can also achieve the purpose of expanding the color range of the light emitted by the light-emitting diode to improve the color gamut. At the same time, since the phosphor is usually encapsulated on the epitaxial layer after the epitaxial layer is prepared, the distance between the phosphor and the light-emitting layer in the epitaxial layer is relatively far, which will affect the excitation energy received by the phosphor, resulting in a decrease in the luminous efficiency of the phosphor, and thus the color purity of the phosphor is poor. In the embodiment of the present disclosure, two light-emitting layers of different colors are directly arranged in a stack, and the light of the required color is synthesized by using the different colors emitted by the two light-emitting layers. Therefore, there will be no problem that the emitted color is not bright enough, and the color of the emitted light can be closer to the monochromatic light in the spectrum, improving the color purity of the light-emitting diode and improving the light-emitting effect.

[0035] Optionally, the ratio of the luminous intensity of the first light-emitting layer 31 to the luminous intensity of the second light-emitting layer 32 is 3.6:10 to 4.8:10.

[0036] By controlling the ratio of the green light intensity to the blue light intensity within 0.5, the energy loss of converting high-energy blue light into green light can be reduced, thereby improving the overall light efficiency; since the current threshold of the blue LED chip is low, by increasing the proportion of blue light, the efficiency attenuation or heating problem caused by over-driving the green light module can be avoided. And too high a proportion of green light may cause the color of the object to appear cyan. Controlling the ratio of the green light intensity to the blue light intensity within the above range helps to form a smoother continuous spectrum and improve the color realism.

[0037] Optionally, the ratio of the luminous intensity of the first light-emitting layer 31 to the luminous intensity of the second light-emitting layer 32 is 3.6:10 to 4:10.

[0038] By controlling the ratio of the green light intensity to the blue light intensity within the above range, a color temperature range of 3000K to 5000K can be stably output, meeting the requirements of neutral white to warm white, and having good color consistency.

[0039] Optionally, the ratio of the luminous intensity of the first light-emitting layer 31 to the luminous intensity of the second light-emitting layer 32 is 4:10 to 4.8:10.

[0040] Compared with the ratio of the green light intensity to the blue light intensity within 4:10, controlling the ratio of the green light intensity to the blue light intensity to be 4:10 to 4.8:10, the increase in the proportion of green light can make up for the light in the wavelength range of 530 nm to 560 nm to which the human eye is sensitive, and optimize the display effect of cyan-yellow objects. At the same time, when the proportion of green light is close to 50%, the color gamut coverage can be improved to meet the high-end display requirements.

[0041] Optionally, the first light-emitting layer 31 includes 1 to 10 pairs of quantum barrier layers and quantum well layers stacked alternately, and the second light-emitting layer 32 includes 5 to 50 pairs of quantum barrier layers and quantum well layers stacked alternately.

[0042] Exemplarily, the green light-emitting layer includes alternately grown InGaN quantum well layers and GaN quantum barrier layers. The green light-emitting layer may include 1 to 10 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0043] Exemplarily, the blue light-emitting layer includes alternately grown InGaN quantum well layers and GaN quantum barrier layers. The third light-emitting layer may include 5 to 50 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0044] In the embodiment of the present disclosure, the first light-emitting layer 31 is a green light-emitting layer, the second light-emitting layer 32 is a blue light-emitting layer, and the green light emitted by the first light-emitting layer 31 and the blue light emitted by the second light-emitting layer 32 can form cyan light after mixing. The cyan light can fill the spectral gap in the LED white light illumination, forming a more saturated spectral of the white light source to improve the illumination quality.

[0045] At the same time, controlling the number of periods of the quantum barrier layers and quantum well layers of the first light-emitting layer 31 and the second light-emitting layer 32 within the above range can keep the ratio of the light intensity of the first light-emitting layer 31 to the light intensity of the second light-emitting layer 32 in a suitable interval, so as to ensure better color purity of the cyan light obtained by mixing the light emitted by the first light-emitting layer 31 and the second light-emitting layer 32.

[0046] Optionally, the light intensity of the first light-emitting layer 31 is positively correlated with the logarithm of the number of pairs of quantum barrier layers and quantum well layers, and the light intensity of the second light-emitting layer 32 is positively correlated with the logarithm of the number of pairs of quantum barrier layers and quantum well layers.

[0047] In the embodiment of the present disclosure, the more the number of alternating layers of the quantum well layers and quantum barrier layers in the light-emitting layer, the greater the light intensity of the light-emitting layer. Therefore, the number of periods of the quantum well layers and quantum barrier layers in the light-emitting layer can be adjusted so that the light intensity of the light-emitting layer meets the usage requirements.

[0048] Exemplarily, the first light-emitting layer 31 includes 3 pairs of quantum barrier layers and quantum well layers stacked alternately, and the second light-emitting layer 32 includes 10 pairs of quantum barrier layers and quantum well layers stacked alternately.

[0049] Figure 2 It is the spectral diagram of a light-emitting diode provided by an embodiment of the present disclosure. Figure 2 It shows the spectral diagram of a light-emitting diode in which the number of periods of the quantum well layer and the quantum barrier layer of the first light-emitting layer 31 is 3, and the number of periods of the quantum well layer and the quantum barrier layer of the second light-emitting layer 32 is 10. As Figure 2 shown, the light intensity of blue light is 100%, and the light intensity of green light is 20%, that is, the ratio of the light intensity of the first light-emitting layer 31 to the light intensity of the second light-emitting layer 32 is 2:10.

[0050] In the embodiment of the present disclosure, the blue light intensity is 5 times that of the green light intensity. After mixing, cyan light will be obtained, and the color depth of the cyan light will be different. Since the blue light intensity is relatively large, the component of blue light in the mixed color will be more prominent, so the obtained cyan light will be more biased towards the cyan tone on the blue light side.

[0051] Exemplarily, the first light-emitting layer 31 includes 6 pairs of alternately stacked quantum barrier layers and quantum well layers, and the second light-emitting layer 32 includes 9 pairs of alternately stacked quantum barrier layers and quantum well layers.

[0052] Figure 3 It is the spectral diagram of another light-emitting diode provided by an embodiment of the present disclosure. Figure 3 It shows the spectral diagram of a light-emitting diode in which the number of periods of the quantum well layer and the quantum barrier layer of the first light-emitting layer 31 is 6, and the number of periods of the quantum well layer and the quantum barrier layer of the second light-emitting layer 32 is 9. As Figure 3 shown, the light intensity of blue light is 100%, and the light intensity of green light is 36%, that is, the ratio of the light intensity of the first light-emitting layer 31 to the light intensity of the second light-emitting layer 32 is 3.6:10.

[0053] In the embodiment of the present disclosure, because the component of blue light is more, the mixed light will be more biased towards the cyan on the blue light side. Compared with Figure 2 the light-emitting diode shown, Figure 3 in the light-emitting diode shown, the proportion of green light increases. Therefore, the mixed color will be more biased towards pure cyan or slightly greenish cyan. Therefore, according to the actual designed light-emitting color requirements, technicians can flexibly adjust the number of periods of the quantum well layer and the quantum barrier layer in the light-emitting layer, so as to adjust the inclination degree of cyan towards blue or green, so as to achieve the purpose of controlling the light-emitting color of the light-emitting diode.

[0054] Optionally, the thickness of the quantum well layer of the first light-emitting layer 31 is 2 nm to 5 nm, and the thickness of the quantum barrier layer of the first light-emitting layer 31 is 10 nm to 150 nm.

[0055] Exemplarily, the thickness of the quantum well layer of the first light-emitting layer 31 is 3 nm, and the thickness of the quantum barrier layer of the first light-emitting layer 31 is 12.5 nm.

[0056] Optionally, the thickness of the quantum well layer of the second light-emitting layer 32 is 2 nm to 5 nm, and the thickness of the quantum barrier layer of the second light-emitting layer 32 is 8 nm to 14 nm.

[0057] Exemplarily, the thickness of the quantum well layer of the second light-emitting layer 32 is 3.5 nm, and the thickness of the quantum barrier layer of the second light-emitting layer 32 is 9.6 nm.

[0058] In the above implementation, the thickness of the quantum barrier layer of the light-emitting layer is greater than that of the quantum well layer, making the quantum well layer relatively thin, so that electrons and holes are more easily quantum-confined in the well, increasing the probability of radiative recombination, thereby improving the light-emitting efficiency. Moreover, the thinner quantum well layer reduces the possibility of photons being absorbed in the well, further improving the light-emitting efficiency. At the same time, the thicker quantum barrier layer can more effectively confine the movement of electrons and holes, making them recombine and emit light more effectively in the quantum well.

[0059] Optionally, as Figure 1 shown, the light-emitting diode further includes: a superlattice layer 61 and a pre-multi-quantum well layer 62. The superlattice layer 61 and the pre-multi-quantum well layer 62 are sequentially stacked on the first semiconductor layer 20 and are located between the first semiconductor layer 20 and the first light-emitting layer 31. Both the superlattice layer 61 and the pre-multi-quantum well layer 62 include a plurality of quantum well layers and quantum barrier layers stacked alternately.

[0060] Exemplarily, the quantum well layer of the superlattice layer 61 is an In x Ga 1-x N layer (0 < x < 0.1), and the quantum barrier layer of the superlattice layer 61 is a GaN layer.

[0061] Exemplarily, the quantum well layer of the pre-multi-quantum well layer 62 is an In x Ga 1-x N layer (0 < x < 0.1), and the quantum barrier layer of the pre-multi-quantum well layer 62 is a GaN layer.

[0062] In the embodiments of the present disclosure, by providing the superlattice layer 61, the dislocation density can be effectively reduced, the crystal quality can be improved, and thus the light-emitting efficiency and reliability of the light-emitting diode can be enhanced. Among them, the provided pre-multi-quantum well layer 62 can improve the quality and uniformity of the multi-quantum well.

[0063] Optionally, one of the first semiconductor layer 20 and the second semiconductor layer 40 is an n-type layer, and the other of the first semiconductor layer 20 and the second semiconductor layer 40 is a p-type layer.

[0064] As an example, in the embodiments of the present disclosure, the first semiconductor layer 20 is an n-type layer and the second semiconductor layer 40 is a p-type layer.

[0065] Among them, the n-type layer can be an n-type GaN layer, and the thickness of the n-type layer is 1 μm to 2 μm.

[0066] Optionally, as Figure 1 shown, the second semiconductor layer 40 includes a low-temperature p-type GaN layer 41, an electron blocking layer 42, a high-temperature p-type GaN layer 43, and a p-type contact layer 44 that are sequentially stacked on the second light-emitting layer 32.

[0067] Exemplarily, the thickness of the low-temperature p-type GaN layer 41 is 15 nm to 40 nm. The low-temperature p-type GaN layer 41, as a protective layer, can reduce the impact on the multi-quantum well layer during the growth of the high-temperature p-type GaN layer 43, and prevent the multi-quantum well structure and optoelectronic characteristics from being affected by high temperature. At the same time, the growth temperature of the low-temperature p-type GaN layer 41 is relatively low. Through low-temperature growth, the thickness and surface morphology of the p-type GaN layer can be better controlled, thereby optimizing the optoelectronic performance of the light-emitting diode.

[0068] Exemplarily, the electron blocking layer 42 can be at least one of an aluminum oxide layer, a titanium oxide layer, and gallium nitride. Among them, the thickness of the electron blocking layer 42 is 15 nm to 35 nm. By restricting the diffusion of electrons, the electron blocking layer 42 helps to confine electrons and holes within the light-emitting layer, thereby improving the internal quantum efficiency and light-emitting efficiency of the light-emitting diode.

[0069] Exemplarily, the thickness of the high-temperature p-type GaN layer 43 is 40 nm to 150 nm. The high-temperature p-type GaN layer 43 helps to increase the hole concentration, thereby improving the internal quantum efficiency and light-emitting efficiency of the light-emitting diode. Moreover, the growth temperature of the high-temperature p-type GaN layer 43 is relatively high. High-temperature growth can reduce carbon impurities, increase the surface mobility of metal atoms, and promote the lateral growth rate of GaN, thereby obtaining higher-quality crystals.

[0070] Exemplarily, the p-type contact layer 44 can be a Mg-doped gallium nitride layer. The p-type contact layer 44 is used to achieve ohmic contact between the epitaxial wafer and the electrode or transparent conductive thin film formed during the chip manufacturing process.

[0071] Among them, the thickness of the p-type contact layer 44 is 1 nm to 6 nm.

[0072] Optionally, as Figure 1 shown, the light-emitting diode further includes a substrate 10, a buffer layer 51, and a U-shaped GaN layer 52. The buffer layer 51 and the U-shaped GaN layer 52 are sequentially stacked on the substrate 10, and the first semiconductor layer 20 is located on the U-shaped GaN layer 52.

[0073] Exemplarily, the substrate is a sapphire substrate, a silicon substrate, silicon carbide, or a silicon oxide substrate. The substrate can be a flat substrate or a patterned substrate.

[0074] As an example, in the embodiments of the present disclosure, the substrate is a silicon oxide substrate.

[0075] Exemplarily, the buffer layer 51 may be at least one of a GaN layer, an AlN layer, and an AlGaN layer.

[0076] For example, the buffer layer 51 includes a stacked low-temperature GaN layer and a high-temperature GaN layer.

[0077] Among them, the U-shaped GaN layer 52 can provide a relatively flat GaN surface, create good conditions for the growth of the subsequent n-type GaN layer, reduce lattice mismatch, and reduce crystal defects.

[0078] Figure 4 It is a flowchart of a method for manufacturing a light-emitting diode provided by the embodiments of the present disclosure. As Figure 4 shown, the manufacturing method includes:

[0079] Step 101: Form a first semiconductor layer 20 on a substrate.

[0080] Exemplarily, the substrate is a sapphire substrate, a silicon substrate, silicon carbide, or a silicon oxide substrate. The substrate may be a flat substrate or a patterned substrate.

[0081] As an example, in the embodiments of the present disclosure, the substrate is a silicon oxide substrate.

[0082] Before epitaxial growth, the substrate is pre-treated, which may specifically include: performing high-temperature cleaning on the substrate in a hydrogen atmosphere at 1000°C to 1200°C for 5 minutes to 20 minutes, and then performing nitridation treatment.

[0083] Before growing the first semiconductor layer 20 in step 101, it may further include: sequentially growing a buffer layer 51 and a U-shaped GaN layer 52 on the substrate.

[0084] In the embodiments of the present disclosure, the buffer layer 51, the U-shaped GaN layer 52, and the epitaxial layer are all grown in a reaction chamber. The reaction chamber is a reaction chamber of a MOCVD (Metal Organic Chemical Vapor Deposition) device.

[0085] Among them, when growing each film layer, the growth substrate is placed in a graphite disk in the MOCVD reaction chamber. By introducing MO sources and reaction gases into the reaction chamber and controlling the rotation of the graphite disk, each film layer is formed on the substrate in the graphite disk.

[0086] The specific process of growing the growth buffer layer 51 may include: lowering the temperature to 700°C to 900°C, first growing a low-temperature GaN layer with a thickness of 2 nm to 10 nm, then raising the temperature to 1000°C to 1100°C, annealing for 3 min to 10 min, with a growth pressure of 50 Torr to 200 Torr, a V / III ratio of 50 to 300, and a rotation speed of the graphite disk of 500 r / min to 1000 r / min.

[0087] Exemplarily, the buffer layer 51 may be at least one of a GaN layer, an AlN layer, and an AlGaN layer.

[0088] For example, the buffer layer 51 includes a stacked low-temperature GaN layer and a high-temperature GaN layer.

[0089] The specific process of growing the U-shaped GaN layer 52 may include: adjusting the temperature to 1000°C to 1200°C, growing a U-shaped GaN layer 52 with a thickness of 1 μm to 2 μm, with a growth pressure of 100 Torr to 500 Torr, a rotation speed of the graphite disk of 600 r / min to 1000 r / min, and a V / III ratio of 200 to 3000.

[0090] Among them, the U-shaped GaN layer 52 can provide a relatively flat GaN surface, create good conditions for the growth of the subsequent n-type GaN layer, reduce lattice mismatch, and reduce crystal defects.

[0091] In the embodiments of the present disclosure, one of the first semiconductor layer 20 and the second semiconductor layer 40 is an n-type layer, and the other of the first semiconductor layer 20 and the second semiconductor layer 40 is a p-type layer.

[0092] As an example, in the embodiments of the present disclosure, the first semiconductor layer 20 is an n-type layer, and the second semiconductor layer 40 is a p-type layer.

[0093] The specific process of growing the first semiconductor layer 20 may include: growing a Si-doped concentration-stabilized n-type GaN layer with a thickness of 1 μm to 2 μm, with a growth temperature of 1050°C to 1150°C, a growth pressure of 100 Torr to 300 Torr, a rotation speed of the graphite disk of 600 r / min to 1200 r / min, and a V / III ratio of 400 to 3000.

[0094] After growing the first semiconductor layer 20 in step 101, it may further include successively growing a superlattice layer 61 and a pre-multiple quantum well layer 62 on the surface of the first semiconductor layer 20.

[0095] Exemplarily, the quantum well layer of the superlattice layer 61 is an In x Ga 1-x N layer (0 < x < 0.1), and the quantum barrier layer of the superlattice layer 61 is a GaN layer.

[0096] Among them, the superlattice layer 61 includes 3 to 10 successively overlapping quantum well layers and quantum barrier layers.

[0097] When growing the superlattice layer 61, control the growth temperature of the In x Ga 1-x N layer to be 750°C to 850°C, the growth pressure to be 100 Torr to 500 Torr, the thickness to be 1 nm to 4 nm, and the V / III ratio to be 500 to 10,000. The growth temperature of the GaN quantum barrier layer is 850°C to 950°C, the growth pressure is 100 Torr to 500 Torr, the V / III ratio is 500 to 10,000, and the thickness is 10 nm to 30 nm.

[0098] Exemplarily, the quantum well layer of the pre-multi-quantum well layer 62 is an In x Ga 1-x N layer (0 < x < 0.1), and the quantum barrier layer of the pre-multi-quantum well layer 62 is a GaN layer.

[0099] Among them, the pre-multi-quantum well layer 62 includes 3 to 10 successively overlapping quantum well layers and quantum barrier layers.

[0100] When growing the pre-multi-quantum well layer 62, control the In x Ga 1-x The growth temperature of the N quantum well layer is 750°C to 850°C, the growth pressure is 100 Torr to 500 Torr, the thickness is 1 nm to 4 nm, and the V / III ratio is 500 to 10,000; control the growth temperature of the GaN quantum barrier layer to be 850°C to 950°C, the growth pressure to be 100 Torr to 500 Torr, the V / III ratio to be 500 to 10,000, and the thickness to be 10 nm to 20 nm.

[0101] Step 102: Sequentially form a first light-emitting layer 31 and a second light-emitting layer 32 on the surface of the first semiconductor layer 20.

[0102] Among them, the first light-emitting layer is a green light-emitting layer, the second light-emitting layer is a blue light-emitting layer, and the ratio of the light-emitting intensity of the first light-emitting layer to the light-emitting intensity of the second light-emitting layer is 2:10 to 4.8:10.

[0103] Exemplarily, the first light-emitting layer 31 includes 1 to 10 pairs of alternately stacked quantum barrier layers and quantum well layers, and the second light-emitting layer 32 includes 5 to 50 pairs of alternately stacked quantum barrier layers and quantum well layers.

[0104] As an example, the green light-emitting layer includes alternately grown InGaN quantum well layers and GaN quantum barrier layers. The green light-emitting layer may include 1 to 10 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0105] As an example, the blue light emitting layer includes alternately grown InGaN quantum well layers and GaN quantum barrier layers. The third light emitting layer may include 5 to 50 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0106] The specific process of growing the first light emitting layer 31 in step 102 includes:

[0107] Controlling the growth temperature to be 700 °C to 780 °C, the growth pressure to be 200 torr to 400 torr, controlling the rotation speed of the graphite disk to be 500 r / min to 1000 r / min, and growing the quantum well layer of the first light emitting layer 31.

[0108] Exemplarily, controlling the growth temperature to be 725 °C, the growth pressure to be 250 torr, controlling the rotation speed of the graphite disk to be 600 r / min, and growing the quantum well layer of the first light emitting layer 31.

[0109] Among them, the thickness of the quantum well layer of the first light emitting layer 31 can be 2 nm to 5 nm. For example, the thickness of the quantum well layer of the first light emitting layer 31 is 3 nm.

[0110] Controlling the growth temperature to be 850 °C to 1000 °C, the growth pressure to be 200 torr to 400 torr, controlling the rotation speed of the graphite disk to be 500 r / min to 1000 r / min, and growing the quantum barrier layer of the first light emitting layer 31.

[0111] Exemplarily, controlling the growth temperature to be 925 °C, the growth pressure to be 250 torr, controlling the rotation speed of the graphite disk to be 600 r / min, and growing the quantum barrier layer of the first light emitting layer 31.

[0112] Among them, the thickness of the quantum barrier layer of the first light emitting layer 31 can be 10 nm to 150 nm. For example, the thickness of the quantum barrier layer of the first light emitting layer 31 is 12.5 nm.

[0113] The specific process of growing the second light emitting layer 32 in step 102 includes:

[0114] Controlling the growth temperature to be 780 °C to 850 °C, the growth pressure to be 150 torr to 300 torr, controlling the rotation speed of the graphite disk to be 500 r / min to 1000 r / min, and growing the quantum well layer of the second light emitting layer 32.

[0115] Exemplarily, controlling the growth temperature to be 801 °C, the growth pressure to be 200 torr, controlling the rotation speed of the graphite disk to be 600 r / min, and growing the quantum well layer of the second light emitting layer 32.

[0116] Among them, the thickness of the quantum well layer of the second light-emitting layer 32 is 2 nm to 5 nm. For example, the thickness of the quantum well layer of the second light-emitting layer 32 is 3.5 nm.

[0117] Control the growth temperature to be 830 °C to 920 °C, the growth pressure to be 150 torr to 300 torr, and control the rotation speed of the graphite disk to be 500 r / min to 1000 r / min to grow the quantum barrier layer of the second light-emitting layer 32.

[0118] Exemplarily, control the growth temperature to be 875 °C, the growth pressure to be 200 torr, and control the rotation speed of the graphite disk to be 600 r / min to grow the quantum barrier layer of the second light-emitting layer 32.

[0119] Among them, the thickness of the quantum barrier layer of the second light-emitting layer 32 is 8 nm to 14 nm. For example, the thickness of the quantum barrier layer of the second light-emitting layer 32 is 9.5 nm.

[0120] Step 103: Form a second semiconductor layer 40 on the surface of the second light-emitting layer 32.

[0121] In the embodiments of the present disclosure, the second semiconductor layer 40 is a p-type layer. As Figure 1 shown, the second semiconductor layer 40 includes a low-temperature p-type GaN layer 41, an electron blocking layer 42, a high-temperature p-type GaN layer 43, and a p-type contact layer 44 stacked in sequence.

[0122] Exemplarily, the thickness of the low-temperature p-type GaN layer 41 is 15 nm to 40 nm. The low-temperature p-type GaN layer 41 serves as a protective layer, which can reduce the influence of the growth of the high-temperature p-type GaN layer 43 on the multi-quantum well layer and prevent the multi-quantum well structure and optoelectronic characteristics from being affected by high temperature.

[0123] Exemplarily, the electron blocking layer 42 can be at least one of an aluminum oxide layer, a titanium oxide layer, and gallium nitride. Among them, the thickness of the electron blocking layer 42 is 15 nm to 35 nm.

[0124] Exemplarily, the thickness of the high-temperature p-type GaN layer 43 is 40 nm to 150 nm. The high-temperature p-type GaN layer 43 helps to increase the hole concentration, thereby improving the internal quantum efficiency and luminous efficiency of the light-emitting diode.

[0125] Exemplarily, the p-type contact layer 44 can be a Mg-doped gallium nitride layer. The p-type contact layer 44 is used to achieve ohmic contact between the epitaxial wafer and the electrode or transparent conductive film formed during the chip manufacturing process.

[0126] Among them, the thickness of the p-type contact layer 44 is 1 nm to 6 nm.

[0127] When growing the low-temperature p-type GaN layer 41, the growth temperature is controlled to be 700 °C to 800 °C, the growth time is 3 min to 15 min, the pressure is 100 Torr to 600 Torr, and the V / III ratio is 1000 to 4000.

[0128] When growing the electron blocking layer 42, the growth temperature is controlled to be 900 °C to 1000 °C, the growth time is 4 min to 15 min, the growth pressure is 50 Torr to 300 Torr, and the V / III ratio is 1000 to 10000.

[0129] When growing the high-temperature p-type GaN layer 43, the growth temperature is controlled to be between 900 °C and 1050 °C, the growth time is 10 min to 20 min, the growth pressure is 100 Torr to 500 Torr, and the V / III ratio is 500 to 4000.

[0130] When growing the p-type contact layer 44, the growth temperature is controlled to be 700 °C to 850 °C, the growth time is 0.5 min to 5 min, the growth pressure is 100 Torr to 500 Torr, and the V / III ratio is 10000 to 20000.

[0131] After step 103, it further includes: annealing the epitaxial wafer.

[0132] After the epitaxial growth is completed, the temperature of the reaction chamber is reduced to 600 °C to 900 °C, and annealing treatment is carried out in a PN 2 atmosphere for 10 min to 30 min, and then gradually reduced to room temperature. Subsequently, single chips are fabricated through subsequent processing steps such as cleaning, deposition, photolithography, and etching.

[0133] In a specific implementation, the embodiments of the present disclosure may use high-purity H 2 or / and N 2 as the carrier gas, use TEGa or TMGa as the Ga source, TMIn as the In source, SiH 4 as the n-type dopant, TMAl as the aluminum source, ammonia gas as the N source, and Cp 2 Mg as the p-type dopant.

[0134] The embodiments of the present disclosure provide Sample 1 and Sample 2, where Sample 1 and Sample 2 are prepared by the preparation method of the embodiments of the present disclosure, and the growth conditions and test results of Sample 1 and Sample 2 are shown in Table 1 below.

[0135] Table 1

[0136]

[0137] In Table 1, the growth conditions of Sample 1 and Sample 2 are the same. The difference is that the cycle period of the quantum well layer and the quantum barrier layer of the green light emitting layer in Sample 1 is 3, and the cycle period of the quantum well layer and the quantum barrier layer of the blue light emitting layer in Sample 1 is 10.

[0138] The cycle period of the quantum well layer and the quantum barrier layer of the green light emitting layer in Sample 2 is 6, and the cycle period of the quantum well layer and the quantum barrier layer of the blue light emitting layer in Sample 2 is 9.

[0139] It can be seen that the cycle number of the blue light emitting layer in Sample 1 is 10, while the cycle number of the green light emitting layer is 3. Therefore, the blue light intensity in Sample 1 is much higher than the green light intensity, and the resulting cyan light after mixing will be more bluish.

[0140] The cycle number of the blue light emitting layer in Sample 2 is 9, while the cycle number of the green light emitting layer is 6. Therefore, the blue light intensity in Sample 2 is slightly higher than the green light intensity. Compared with Sample 1, since the proportion of green light in Sample 2 increases, the resulting color after mixing will be pure cyan or slightly greenish cyan.

[0141] Figure 2 is the measured spectrum of Sample 1, Figure 3 is the measured spectrum of Sample 2. According to Figure 2 and Figure 3 It can be verified that the ratio of the emission intensity of the green light emitting layer to the emission intensity of the blue light emitting layer in Sample 1 is 2:10; the ratio of the emission intensity of the green light emitting layer to the emission intensity of the blue light emitting layer in Sample 2 is 3.6:10. That is, the blue light intensity in Sample 1 is 5 times stronger than the green light intensity, while the blue light intensity in Sample 2 is 2 to 3 times stronger than the green light intensity. Therefore, the cycle number of the sub-quantum well layer and the quantum barrier layer in the light emitting layer can be adjusted to meet the usage requirements of the emission intensity of the light emitting layer.

[0142] The above are only optional embodiments of the present disclosure, and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A light emitting diode, characterized in that: The light-emitting diode comprises a first semiconductor layer (20), a first light-emitting layer (31), a second light-emitting layer (32) and a second semiconductor layer (40) which are stacked in sequence, the first light-emitting layer (31) is a green light-emitting layer, the second light-emitting layer (32) is a blue light-emitting layer, and the ratio of the light-emitting intensity of the first light-emitting layer (31) to the light-emitting intensity of the second light-emitting layer (32) is 2:10 to 4.8:

10.

2. The light emitting diode according to claim 1, characterized in that: The ratio of the luminous intensity of the first luminous layer (31) to the luminous intensity of the second luminous layer (32) is 3.6:10 to 4.8:

10.

3. The light emitting diode according to claim 2, characterized in that: The ratio of the luminous intensity of the first luminous layer (31) to the luminous intensity of the second luminous layer (32) is 3.6:10 to 4:

10.

4. The light emitting diode according to claim 2, characterized in that: The ratio of the luminous intensity of the first luminous layer (31) to the luminous intensity of the second luminous layer (32) is 4:10 to 4.8:

10.

5. The light emitting diode according to any one of claims 1 to 4, characterized in that: The first light-emitting layer (31) comprises 1 to 10 pairs of quantum barrier layers and quantum well layers stacked alternately, and the second light-emitting layer (32) comprises 5 to 50 pairs of quantum barrier layers and quantum well layers stacked alternately.

6. The light emitting diode according to claim 5, characterized in that: The first light-emitting layer (31) comprises three pairs of quantum barrier layers and quantum well layers stacked alternately, and the second light-emitting layer (32) comprises ten pairs of quantum barrier layers and quantum well layers stacked alternately; or, The first light-emitting layer (31) comprises six pairs of quantum barrier layers and quantum well layers stacked alternately, and the second light-emitting layer (32) comprises nine pairs of quantum barrier layers and quantum well layers stacked alternately.

7. The light emitting diode according to claim 6, characterized in that: The thickness of the quantum well layer of the first light-emitting layer (31) is 2 nm to 5 nm, and the thickness of the quantum barrier layer of the first light-emitting layer (31) is 10 nm to 150 nm; The thickness of the quantum well layer of the second light-emitting layer (32) is 2nm to 5nm, and the thickness of the quantum barrier layer of the second light-emitting layer (32) is 8nm to 14nm.

8. A method for preparing a light emitting diode, characterized in that: The preparation method comprises: forming a first semiconductor layer on a substrate; forming a first light-emitting layer and a second light-emitting layer in sequence on the surface of the first semiconductor layer, wherein the first light-emitting layer is a green light-emitting layer, the second light-emitting layer is a blue light-emitting layer, and the ratio of the light-emitting intensity of the first light-emitting layer to the light-emitting intensity of the second light-emitting layer is 2:10 to 4.8:10; A second semiconductor layer is formed on a surface of the second light emitting layer.

9. The preparation method according to claim 8, characterized in that: Forming a first light emitting layer on the first semiconductor layer includes: Controlling the growth temperature to be 700° C. to 780° C., the growth pressure to be 200 torr to 400 torr, and the rotation speed of the graphite disk to be 500 r / min to 1000 r / min to grow the quantum well layer of the first light-emitting layer; The growth temperature is controlled to be 850° C. to 1000° C., the growth pressure is controlled to be 200 torr to 400 torr, and the rotation speed of the graphite disk is controlled to be 500 r / min to 1000 r / min to grow the quantum barrier layer of the first light-emitting layer.

10. The preparation method according to claim 8, characterized in that: Forming a second light-emitting layer on the first light-emitting layer comprises: Controlling the growth temperature to be 780° C. to 850° C., the growth pressure to be 150 torr to 300 torr, and the rotation speed of the graphite disk to be 500 r / min to 1000 r / min to grow the quantum well layer of the second light-emitting layer; The growth temperature is controlled to be 830° C. to 920° C., the growth pressure is controlled to be 150 torr to 300 torr, and the rotation speed of the graphite disk is controlled to be 500 r / min to 1000 r / min to grow the quantum barrier layer of the second light-emitting layer.

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