Multi-junction monolithic light emitting element, method for manufacturing the same, and light emitting device

Abstract

The present application relates to the technical field of semiconductor device manufacturing, and particularly provides a multi-junction monolithic light emitting element, a manufacturing method thereof and a light emitting device. The multi-junction monolithic light emitting element comprises at least: a first light emitting unit comprising, from bottom to top, a first N-type layer, a first light emitting layer and a first P-type layer which are sequentially stacked; a first tunnel junction located above the first light emitting unit and having a non-intentionally doped structure; and a second light emitting unit located above the first tunnel junction and comprising, from bottom to top, a second N-type layer, a second light emitting layer and a second P-type layer which are sequentially stacked; wherein the first light emitting unit and the second light emitting unit are superimposed and electrically connected through the first tunnel junction, and the first light emitting unit, the first tunnel junction and the second light emitting unit are grown in the same device. The multi-junction monolithic light emitting element is grown in the above-mentioned structure and in the same device, which greatly simplifies the growth process flow, simplifies the equipment requirements, and improves the light emitting brightness.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device manufacturing technology, and in particular to a multi-junction monolithic light-emitting element, its manufacturing method, and a light-emitting device. Background Technology

[0002] A light-emitting diode (LED) is a solid-state semiconductor light-emitting element that contains various light-emitting materials and components. Due to its advantages such as low cost, low power consumption, high luminous efficiency, small size, energy saving, environmental friendliness, and good reliability, it is widely used in various scenarios including lighting, visible light communication, and light-emitting displays.

[0003] To improve the luminous efficiency of light-emitting diodes (LEDs), researchers are increasingly exploring the use of tunnel junctions (TJs) to stack two or more LEDs (or PN junctions) to form multi-junction LEDs. Compared to a single LED, a multi-junction LED can emit more light from its emitting surface, thereby increasing its brightness.

[0004] In the fabrication process of multi-junction light-emitting devices (MLEDs), the common growth methods for tunnel junctions and their associated epitaxial structures are as follows: The first method involves cooling the MOCVD after growing the first set of epitaxial structures and removing the epitaxial wafer at atmospheric pressure. This wafer is then reinserted into the MOCVD to grow the tunnel junction and subsequent epitaxial structures of different PN junctions. The second method involves growing the tunnel junction and subsequent epitaxial structures of different PN junctions using other equipment (such as MBE / RPCVD). Existing multi-junction light-emitting device fabrication processes are complex and require diverse equipment. Summary of the Invention

[0005] To achieve at least one or more advantages of the present invention, one embodiment of the present invention provides a multi-junction monolithic light-emitting element, comprising at least: a first light-emitting unit comprising, from bottom to top, a first N-type layer, a first light-emitting layer, and a first P-type layer stacked sequentially; a first tunnel junction located above the first light-emitting unit and having an unintentionally doped structure; and a second light-emitting unit located above the first tunnel junction, comprising, from bottom to top, a second N-type layer, a second light-emitting layer, and a second P-type layer stacked sequentially; wherein the first light-emitting unit and the second light-emitting unit are superimposed and current-conducting through the first tunnel junction, and the first light-emitting unit, the first tunnel junction, and the second light-emitting unit are grown in the same device.

[0006] In some embodiments, the first light-emitting unit includes, from bottom to top, a first N-type layer, a first stress-relieving layer, a first light-emitting layer, a first electron-blocking layer, and a first P-type layer stacked in sequence.

[0007] In some embodiments, the first light-emitting unit may further include a first P-type contact layer located above the first P-type layer, and a first tunnel junction located above the first P-type contact layer. The thickness of the first P-type contact layer is greater than or equal to 1 nanometer and less than or equal to 10 nanometers.

[0008] In some embodiments, the thickness of the first tunnel junction is greater than or equal to 2 nanometers and less than or equal to 20 nanometers.

[0009] In some embodiments, the first tunnel junction is made of unintentionally doped gallium nitride (GaN) or unintentionally doped indium gallium nitride (InGaN).

[0010] In some embodiments, the concentration of carbon atoms in the first tunnel junction is greater than 5E18Atoms / cm3.

[0011] In some embodiments, the second light-emitting unit comprises, from bottom to top, a second N-type layer, a second stress-relieving layer, a second light-emitting layer, a second electron-blocking layer, and a second P-type layer stacked sequentially. The second N-type layer is made of N-type doped gallium nitride with a doping concentration of 5E18 Atoms / cm³ to 5E20 Atoms / cm³. The thickness of the second N-type layer is greater than or equal to 2 nanometers and less than or equal to 300 nanometers. The thickness of the first N-type layer is greater than or equal to the thickness of the second N-type layer.

[0012] In some embodiments, the second light-emitting unit may further include a first N-type contact layer located above the first tunnel junction and below the second N-type layer.

[0013] In some embodiments, the first N-type contact layer is made of N-type doped gallium nitride or indium gallium nitride, with a doping concentration of 5E19 attoms / cm³ to 5E21 attoms / cm³. The thickness of the first N-type contact layer is greater than or equal to 2 nanometers and less than or equal to 50 nanometers. The thickness of the first tunnel junction is greater than the thickness of the first N-type contact layer.

[0014] In some embodiments, the multi-junction monolithic light-emitting element may further include a substrate. One side surface of the substrate includes, from bottom to top, a first light-emitting unit, a first tunnel junction, and a second light-emitting unit stacked sequentially, and an undoped layer may be included between the substrate and the first light-emitting unit.

[0015] In some embodiments, the substrate is at least one of a sapphire substrate, a silicon substrate, and a silicon carbide substrate. The undoped layer is preferably unintentionally doped gallium nitride (U-GaN).

[0016] To achieve at least one or more advantages of the present invention, one embodiment of the present invention provides a multi-junction monolithic light-emitting element, comprising at least: a first light-emitting unit comprising, from bottom to top, a first N-type layer, a first light-emitting layer, and a first P-type layer stacked sequentially; a first tunnel junction located above the first light-emitting unit and having an unintentionally doped structure; a second light-emitting unit located above the first tunnel junction and comprising, from bottom to top, a second N-type layer, a second light-emitting layer, and a second P-type layer stacked sequentially; a second tunnel junction located above the second light-emitting unit and having an unintentionally doped structure; and a third light-emitting unit located above the second tunnel junction and comprising, from bottom to top, a third N-type layer, a third light-emitting layer, and a third P-type layer stacked sequentially; wherein the first light-emitting unit and the second light-emitting unit are superimposed and current-conducting through the first tunnel junction, and the second light-emitting unit and the third light-emitting unit are superimposed and current-conducting through the second tunnel junction, and the first light-emitting unit, the first tunnel junction, the second light-emitting unit, the second tunnel junction, and the third light-emitting unit are grown in the same device.

[0017] In some embodiments, the first tunnel junction and the second tunnel junction have the same structure.

[0018] To achieve at least one or more advantages of the present invention, one embodiment of the present invention provides a light-emitting device, comprising: a substrate; and a light-emitting element mounted on the substrate, wherein the light-emitting element is a multi-junction monolithic light-emitting element as described above.

[0019] To achieve at least one or more advantages of the present invention, one embodiment of the present invention provides a method for manufacturing a multi-junction monolithic light-emitting element, comprising the following steps: providing a substrate; growing a first light-emitting unit on the substrate, the first light-emitting unit comprising, from bottom to top, a first N-type layer, a first stress-relieving layer, a first light-emitting layer, a first electron blocking layer, a first P-type layer, and a first P-type contact layer stacked sequentially; growing a first tunnel junction above the first P-type contact layer to form an interrupt layer; growing a first N-type contact layer above the first tunnel junction; forming a second light-emitting unit on the first N-type contact layer, the second light-emitting unit comprising, from bottom to top, a second N-type layer, a second stress-relieving layer, a second light-emitting layer, a second electron blocking layer, a second P-type layer, and a second P-type contact layer stacked sequentially, thereby forming a multi-junction monolithic light-emitting element.

[0020] In some embodiments, the first light-emitting unit, the first tunnel junction, and the second light-emitting unit are grown in the same device.

[0021] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other beneficial effects of the invention can be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships shown in the drawings in the following description are based on the direction in which the components are drawn in the figure.

[0023] Figure 1 This is a cross-sectional structural diagram of the first embodiment of the multi-junction monolithic light-emitting element in this invention;

[0024] Figure 2 This is a cross-sectional structural diagram of the second embodiment of the multi-junction monolithic light-emitting element in this invention;

[0025] Figure 3 This is a schematic flowchart illustrating a manufacturing method for a multi-junction monolithic light-emitting element according to an embodiment of the present invention.

[0026] Figures 4a to 4d Based on Figure 3 The diagram shows a process flow diagram of one embodiment of the preparation method.

[0027] Reference numerals: 1-Multi-junction monolithic light-emitting element; 10-Substrate; 2-First light-emitting unit; 20-Undoped layer; 21-First N-type layer; 22-First light-emitting layer; 23-First P-type layer; 24-First stress-relieving layer; 25-First electron blocking layer; 26-First P-type contact layer; 27-First low-temperature insertion layer; 3-First tunnel junction; 30-First N-type contact layer; 4-Second light-emitting unit; 41-Second N-type layer; 42-Second light-emitting layer; 43-Second P-type layer; 44-Second stress-relieving layer; 45-Second electron blocking layer; 46-Second P-type contact layer; 47-Second low-temperature insertion layer; 5-Second tunnel junction; 40-Second N-type contact layer; 6-Third light-emitting unit; 61-Third N-type layer; 62-Third light-emitting layer; 63-Third P-type layer; 64-Third stress-relieving layer; 65-Third electron blocking layer; 66-Third P-type contact layer; 67-Third low-temperature insertion layer. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be noted that all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be construed as limiting the invention; it should be further understood that the terms used in this invention should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this invention.

[0030] Please see Figure 1 , Figure 1 This is a cross-sectional structural diagram of the first embodiment of the multi-junction monolithic light-emitting element of the present invention. To achieve at least one or more advantages of the present invention, one embodiment of the present invention provides a multi-junction monolithic light-emitting element 1, comprising at least: a first light-emitting unit 2, comprising, from bottom to top, a first N-type layer 21, a first light-emitting layer 22, and a first P-type layer 23 stacked sequentially; a first tunnel junction 3, located above the first light-emitting unit 2, having an unintentionally doped structure; and a second light-emitting unit 4, located above the first tunnel junction 3, comprising, from bottom to top, a second N-type layer 41, a second light-emitting layer 42, and a second P-type layer 43 stacked sequentially. The first light-emitting unit 2 and the second light-emitting unit 4 are superimposed and current-conducting through the first tunnel junction 3. The first light-emitting unit 2, the first tunnel junction 3, and the second light-emitting unit 4 are grown in the same equipment, which greatly simplifies the growth process, reduces equipment requirements, improves luminous brightness, reduces voltage, reduces leakage current, and thus improves the performance of the multi-junction monolithic light-emitting element 1.

[0031] The multi-junction monolithic light-emitting element 1 may further include a substrate 10. The substrate 10 can be a support substrate or a growth substrate, etc., and can be selected according to the needs of the product manufacturing process. In some specific embodiments, preferably, the substrate 10 is one of a sapphire substrate, a silicon substrate, or a silicon carbide substrate. These are commonly used substrate materials in actual production, and the manufacturing processes are relatively mature, which can reduce the overall cost of the light-emitting element. During the manufacturing process, the first light-emitting unit 2, the first tunnel junction 3, and the second light-emitting unit 4 are formed on the substrate 10. As shown in the figure, one side surface of the substrate 10 includes, from bottom to top, the first light-emitting unit 2, the first tunnel junction 3, and the second light-emitting unit 4 stacked sequentially.

[0032] In some specific embodiments, as shown in the figure, an undoped layer 20 may be included between the substrate 10 and the first light-emitting unit 2 to reduce lattice mismatch defects between the substrate 10 and the first light-emitting unit 2, improve the crystal quality of the first light-emitting unit 2, and thus improve the photoelectric performance of the first light-emitting unit 2. Generally, the undoped layer 20 and the N-type or P-type semiconductor layer in the first light-emitting unit 2 that contacts the undoped layer 20 are made of the same material, thereby ensuring the adhesion and performance between the undoped layer 20 and the first light-emitting unit 2. In some specific embodiments, preferably, the undoped layer 20 is unintentionally doped gallium nitride (U-GaN).

[0033] The first light-emitting unit 2 is formed on one side surface of the substrate 10. In some embodiments, the first light-emitting unit 2 may include, from bottom to top, at least a first N-type layer 21, a first stress-relieving layer 24, a first light-emitting layer 22, a first electron blocking layer (EBL) 25, and a first P-type layer 23 stacked in sequence. In some embodiments, the first N-type layer 21 and the first P-type layer 23 are preferably made of gallium nitride (GaN).

[0034] In some specific embodiments, such as Figure 1 As shown, a first stress-relieving layer 24 may be provided between the first N-type layer 21 and the first light-emitting layer 22 to balance the internal stress in the first light-emitting unit 2, thereby improving the reliability and performance of the first light-emitting unit 2. In some specific embodiments, a first electron blocking layer (EBL) 25 may be provided between the first light-emitting layer 22 and the first P-type layer 23 to control the flow of electrons in the first light-emitting unit 2 and improve the luminous efficiency. A first low-temperature insertion layer 27 may also be provided between the first light-emitting layer 22 and the first electron blocking layer (EBL) 25 to increase the number of holes, thereby increasing the radiative recombination of electrons and holes and improving the luminous efficiency of the first light-emitting unit 2.

[0035] The first tunnel junction 3 is formed on the surface of the first light-emitting unit 2 away from the substrate 10. In the illustration, the first tunnel junction 3 is formed on the surface of the first P-type layer 23 in the first light-emitting unit 2 away from the first light-emitting layer 22. The material of the first tunnel junction 3 is preferably unintentionally doped gallium nitride (GaN) or unintentionally doped indium gallium nitride (InGaN), but is not limited to these two materials. Excessive or insufficient thickness of the first tunnel junction 3 can easily lead to excessively high voltage in the multi-junction monolithic light-emitting element 1, thereby affecting the performance of the multi-junction monolithic light-emitting element 1. Preferably, the thickness of the first tunnel junction 3 is greater than or equal to 2 nanometers and less than or equal to 20 nanometers, which ensures that the first light-emitting unit 2 and the second light-emitting unit 4 are connected and electrically conductive through the first tunnel junction 3, while also ensuring the overall stability of the multi-junction monolithic light-emitting element 1.

[0036] Generally, after the multi-junction monolithic light-emitting element 1 is formed through one-time growth and two-time growth, the carbon atom concentration in the first tunnel junction 3 differs. The carbon atom concentration in the first tunnel junction 3 is related to the growth temperature of the first tunnel junction 3. The higher the growth temperature of the first tunnel junction 3, the lower the carbon atom concentration in the first tunnel junction 3; the lower the growth temperature of the first tunnel junction 3, the higher the carbon atom concentration in the first tunnel junction 3. In some specific embodiments, preferably, the growth temperature of the first tunnel junction 3 is 750℃-950℃, and the carbon atom concentration in the first tunnel junction 3 is greater than 5E18 atoms / cm3.

[0037] If a single-junction (one light-emitting unit) light-emitting element has a luminance (LOP) of 177.9mW, a voltage (VF1) of 2.964V, and a leakage current (IR) of 0.003mA. If a single-junction (two light-emitting units) light-emitting element has no tunnel junction and is formed by two separate growth processes, its luminance (LOP) is 78.4mW, its voltage (VF1) is 8.674V, and its leakage current (IR) is 23.9mA. This results in severe leakage and affects overall performance. In an embodiment of this invention, the multi-junction single-junction light-emitting element 1 has two or more junctions and a tunnel junction, formed by a single growth process. Its luminance (LOP) is 293.8mW, its voltage (VF1) is 7.373V, and its leakage current (IR) is 0.002mA. Generally, the voltage of a double-junction monolithic light-emitting element is higher than that of a single-junction monolithic light-emitting element; the voltage of a double-junction monolithic light-emitting element is 2-3 times that of a single-junction monolithic light-emitting element. Among double-junction or multi-junction monolithic light-emitting elements, within the product's preset voltage fluctuation range, the lower the voltage, the better the product's performance. Compared with single-junction monolithic light-emitting elements and double-junction monolithic light-emitting elements (without a tunnel junction), the multi-junction monolithic light-emitting element 1 provided by this invention has significant advantages in brightness, voltage, and leakage current, resulting in better overall performance.

[0038] In some specific embodiments, as shown in the figure, the first light-emitting unit 2 may further include a first P-type contact layer 26. The first P-type contact layer 26 is located above the first P-type layer 23, and the first tunnel junction 3 is located above the first P-type contact layer 26. In other words, the first P-type contact layer 26 is disposed between the first P-type layer 23 and the first tunnel junction 3 in the first light-emitting unit 2. The thickness of the first P-type contact layer 26 is greater than or equal to 1 nanometer and less than or equal to 10 nanometers. The arrangement of the first P-type contact layer 26 facilitates current conduction between the first light-emitting unit 2 and the first tunnel junction 3.

[0039] The second light-emitting unit 4 is formed on the surface of the first tunnel junction 3 on the side away from the first light-emitting unit 2. In some embodiments, the second light-emitting unit 4 may include, from bottom to top, at least a second N-type layer 41, a second stress-relieving layer 44, a second light-emitting layer 42, a second electron-blocking layer 45, and a second P-type layer 43 stacked in sequence. In some embodiments, preferably, the second N-type layer 41 is made of N-type doped gallium nitride with a doping concentration of 5E18 Atoms / cm3 to 5E20 Atoms / cm3. The thickness of the second N-type layer 41 is greater than or equal to 2 nanometers and less than or equal to 300 nanometers. In some embodiments, preferably, the second N-type layer 41 and the second P-type layer 43 are made of gallium nitride (GaN).

[0040] The thicknesses of the first N-type layer 21 and the second N-type layer 41 can be the same or different, depending on the actual needs of the product. In some specific embodiments, preferably, the thickness of the first N-type layer 21 is greater than or equal to the thickness of the second N-type layer 41. If the second N-type layer 41 in the second light-emitting unit 4 is grown at high temperature, it will cause the first light-emitting layer 22 in the first light-emitting unit 2 located below it to be lost. Therefore, the second N-type layer 41 is generally grown at low temperature. However, low temperature growth is prone to other defects. By controlling the thickness of the second N-type layer 41 to be less than or equal to the thickness of the first N-type layer 21 under low temperature growth, the generation of defects can be reduced, the growth quality can be improved, and thus the performance of the multi-junction monolithic light-emitting element 1 can be improved.

[0041] A second stress-relieving layer 44 may be provided between the second N-type layer 41 and the second light-emitting layer 42 to balance the internal stress in the second light-emitting unit 4, thereby improving the reliability and performance of the second light-emitting unit 4. A second electron blocking layer (EBL) 45 may be provided between the second light-emitting layer 42 and the second P-type layer 43 to control the flow of electrons in the second light-emitting unit 4 and improve the luminous efficiency. A second low-temperature insertion layer 47 may be provided between the second light-emitting layer 42 and the second electron blocking layer (EBL) 45 to increase the number of holes, thereby increasing the radiative recombination of electrons and holes and improving the luminous efficiency of the second light-emitting unit 4.

[0042] In some specific embodiments, as shown in the figure, the second light-emitting unit 4 may further include a first N-type contact layer 30, located above the first tunnel junction 3 and below the second N-type layer 41. In other words, the first N-type contact layer 30 is disposed between the second N-type layer 41 and the first tunnel junction 3 in the second light-emitting unit 4, which is beneficial for current conduction between the second light-emitting unit 4 and the first tunnel junction 3.

[0043] In a preferred embodiment, the first N-type contact layer 30 is made of N-type doped gallium nitride or indium gallium nitride, with a doping concentration of 5E19 to 5E21 atmos / cm3. The thickness of the first N-type contact layer 30 is greater than or equal to 2 nanometers and less than or equal to 50 nanometers. Among the first tunnel junction 3, the first N-type contact layer 30, and the first P-type contact layer 26, the first P-type contact layer 26 is the thinnest. If the thickness of the first P-type contact layer 26 is too high, the voltage in the multi-junction monolithic light-emitting element 1 will be higher than expected, the current conduction effect between the first light-emitting unit 2 and the second light-emitting unit 4 will decrease, and thus affect the overall performance and stability of the multi-junction monolithic light-emitting element 1.

[0044] In the multi-junction monolithic light-emitting element 1, the first N-type contact layer 30 and the first P-type contact layer 26 are both highly doped, with concentrations higher than those of the underlying layers of the same doping type. The first N-type layer 21 and the first P-type layer 23 of the first light-emitting unit 2, and the second N-type layer 41 and the second P-type layer 43 of the second light-emitting unit 4 are also highly doped, but the doping concentrations of these N-type and P-type layers are lower than those of the first N-type contact layer 30 and the first P-type contact layer 26, so as to provide more electrons and holes and improve luminous efficiency.

[0045] The concentrations of the first N-type layer 21 and the first P-type layer 23 are relatively high to provide more electrons and holes. The concentrations of the first N-type layer 21 and the first P-type layer 23 are lower than the concentration of the first P-type contact layer 26.

[0046] High doping concentrations of the N-type and P-type layers provide more holes and electrons, increasing the recombination efficiency and thus improving the brightness of the multi-junction monolithic light-emitting element 1. Furthermore, generally, higher doping concentrations of the first N-type contact layer 30 and the first P-type contact layer 26 result in lower resistance with the N-type and P-type layers, respectively. This facilitates the formation of ohmic contacts with the N-type and P-type layers, promoting current diffusion and improving the current conduction between the first light-emitting unit 2 and the second light-emitting unit 4, thereby enhancing the overall performance and stability of the multi-junction monolithic light-emitting element 1.

[0047] Please cooperate. Figure 1 See Figure 2 , Figure 2This is a cross-sectional structural diagram of a second embodiment of the multi-junction monolithic light-emitting element of the present invention. To achieve at least one or more advantages of the present invention, one embodiment of the present invention provides a multi-junction monolithic light-emitting element 1, comprising at least: a first light-emitting unit 2, comprising, from bottom to top, a first N-type layer 21, a first light-emitting layer 22, and a first P-type layer 23 stacked sequentially; a first tunnel junction 3, located above the first light-emitting unit 2, having an unintentionally doped structure; a second light-emitting unit 4, located above the first tunnel junction 3, comprising, from bottom to top, a second N-type layer 41, a second light-emitting layer 42, and a second P-type layer 43 stacked sequentially; and a second tunnel junction 5, located above the second light-emitting unit 2. Above 4, there is an unintentionally doped structure; and a third light-emitting unit 6, located above the second tunnel junction 5, including a third N-type layer 61, a third light-emitting layer 62 and a third P-type layer 63 stacked sequentially from bottom to top; wherein, the first light-emitting unit 2 and the second light-emitting unit 4 are superimposed and current-conducted through the first tunnel junction 3, and the second light-emitting unit 4 and the third light-emitting unit 6 are superimposed and current-conducted through the second tunnel junction 5, and the first light-emitting unit 2, the first tunnel junction 3, the second light-emitting unit 4, the second tunnel junction 5 and the third light-emitting unit 6 are grown in the same device.

[0048] In one specific embodiment, as shown in the figure, the first tunnel junction 3 and the second tunnel junction 5 may have the same structure. The first light-emitting unit 2, the second light-emitting unit 4, and the third light-emitting unit 6 may have the same structure.

[0049] Figure 2 The multi-junction monolithic light-emitting element 1 shown is a triple-junction structure, and... Figure 1 The structural arrangement of the corresponding light-emitting unit in the multi-junction monolithic light-emitting element 1 with the double-junction structure shown is as follows: Figure 1 The descriptions of the embodiments shown are identical and will not be repeated here.

[0050] To achieve at least one or more advantages of the present invention, one embodiment of the present invention provides a light-emitting device, comprising: a substrate; and a light-emitting element mounted on the substrate, wherein the light-emitting element is a multi-junction monolithic light-emitting element 1 as described above.

[0051] Please combine Figure 1 See Figure 3 and Figures 4a to 4d , Figure 3 This is a schematic flowchart illustrating the manufacturing method of a multi-junction monolithic light-emitting element according to an embodiment of the present invention. Figures 4a to 4d Based on Figure 3 A schematic diagram of the process of one embodiment of the preparation method shown. Using... Figure 3 The manufacturing method of the multi-junction monolithic light-emitting element shown obtains as follows: Figure 1 The process flow of the multi-junction monolithic light-emitting element is described below, but the manufacturing method of the multi-junction monolithic light-emitting element is not limited to this.

[0052] To achieve at least one or more advantages of the present invention, one embodiment of the present invention provides a method for manufacturing a multi-junction monolithic light-emitting element 1, which may include at least the following steps: growing a first light-emitting unit 2, growing a first tunnel junction 3, growing a first N-type contact layer 30, and growing a second light-emitting unit 4. For ease of explanation, this embodiment uses a multi-junction monolithic light-emitting element 1 with a double-junction structure as an example to illustrate its manufacturing method. The manufacturing method of monolithic light-emitting elements with three or more junctions is similar to that of the double-junction structure, the main difference being that there are repeated steps in the intermediate process of growing the first light-emitting unit 2 and / or the second light-emitting unit 4 and the tunnel junction.

[0053] Step S11: Grow the first light-emitting unit 2

[0054] like Figure 4a As shown, a substrate 10 is provided, and a first light-emitting unit 2 is grown on one surface of the substrate 10 using metal-organic chemical vapor deposition (MOCVD). The substrate 10 can be a sapphire substrate, a silicon substrate, or a silicon carbide substrate. The first light-emitting unit 2 includes, from bottom to top, a first N-type layer 21, a first stress-relieving layer 24, a first light-emitting layer 22, a first electron-blocking layer 25, a first P-type layer 23, and a first P-type contact layer 26, stacked sequentially. A first low-temperature insertion layer 27 may also be provided between the first light-emitting layer 22 and the first electron-blocking layer 25 in the first light-emitting unit 2.

[0055] Step S12: Grow the first tunnel junction 3

[0056] like Figure 4b As shown, a first tunnel junction 3 is grown on the surface of the first P-type contact layer 26 of the first light-emitting unit 2, away from the first P-type layer 23, to form an interrupt layer. Other light-emitting units are grown on the first light-emitting unit 2 to achieve current conduction. In some specific embodiments, preferably, the growth temperature of the first tunnel junction 3 is 750℃-950℃.

[0057] Step S13: Grow the first N-type contact layer 30

[0058] like Figure 4c As shown, a first N-type contact layer 30 is grown above the first tunnel junction 3. The first N-type contact layer 30 is located on the surface of the first tunnel junction 3 away from the first light-emitting unit 2. In some specific embodiments, preferably, the growth temperature of the first N-type contact layer 30 is 750°C-950°C.

[0059] Step S14: Grow the second light-emitting unit 4

[0060] like Figure 4dAs shown, a second light-emitting unit 4 is formed on the first N-type contact layer 30. The second light-emitting unit 4 includes, from bottom to top, a second N-type layer 41, a second stress-relieving layer 44, a second light-emitting layer 42, a second electron blocking layer 45, a second P-type layer 43, and a second P-type contact layer 46 stacked sequentially, thereby forming a multi-junction monolithic light-emitting element 1. A second low-temperature insertion layer 47 may also be provided between the second light-emitting layer 42 and the second electron blocking layer 45 in the second light-emitting unit 4. In some specific embodiments, preferably, the growth temperature of the second P-type contact layer 46 is 750℃-950℃. In the multi-junction monolithic light-emitting element 1, the second P-type contact layer 46 or the Nth P-type contact layer is provided in the uppermost light-emitting unit of a double-junction or triple-junction unit 4, which is beneficial for forming ohmic contacts with electrodes and for current conduction between different light-emitting units.

[0061] In some specific embodiments, during the manufacturing process, the first light-emitting unit 2, the first tunnel junction 3, and the second light-emitting unit 4 are grown in the same equipment, which can greatly simplify the growth process, simplify equipment requirements, improve light emission brightness, reduce voltage, reduce leakage current, and thus improve the performance of the multi-junction monolithic light-emitting element 1.

[0062] In some specific embodiments, preferably, the manufacturing method of the multi-junction monolithic light-emitting element 1 may further include the following steps: growing a second tunnel junction 5 on the surface of the second P-type contact layer 46 of the second light-emitting unit 4 away from the second P-type layer 43. The second tunnel junction 5 may have the same structure as the first tunnel junction 3. Growing a third light-emitting unit 6 on the surface of the second tunnel junction 5 away from the second light-emitting unit 4, the third light-emitting unit 6 may have the same structural configuration as the second light-emitting unit 4. In other words, the multi-junction monolithic light-emitting element 1 is a double-junction structure (a junction refers to a light-emitting unit) or a multi-junction structure. Different junctions are connected through tunnel junctions to achieve current conduction between different light-emitting units.

[0063] In summary, compared with existing technologies, the multi-junction monolithic light-emitting element 1 provided by this invention, through its tunnel junction structure, avoids the impact of Mg residue in the MOCVD process on the quality of the tunnel junction. Furthermore, it allows for the simultaneous growth of two or more light-emitting units in MOCVD, significantly simplifying the process steps, reducing equipment requirements, and lowering overall manufacturing costs. Moreover, since multiple light-emitting units and the tunnel junction in the multi-junction monolithic light-emitting element 1 are grown in a single MOCVD process, there is no need to remove and process each light-emitting unit after its growth. This reduces the damage to the epitaxial film layer in the light-emitting unit caused by water and oxygen (air), and avoids affecting the growth quality of the subsequent second and / or third light-emitting units and preventing leakage current. This results in lower voltage, increased brightness, and improved performance of the multi-junction monolithic light-emitting element 1.

[0064] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or the background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0065] Although this document frequently uses terms such as multi-junction monolithic light-emitting element, tunnel junction, light-emitting unit, N-type contact layer, and P-type contact layer, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention. The terms "upper," "lower," "vertical," "horizontal," "top," "bottom," "upper surface," "left," "right," "sidewall," and "directly above" in the specification, claims, and accompanying drawings of the embodiments of the invention indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-junction monolithic light-emitting element, characterized in that, At least including: The first light-emitting unit comprises, from bottom to top, a first N-type layer, a first light-emitting layer, and a first P-type layer stacked in sequence. The first tunnel junction, located above the first light-emitting unit, is an unintentionally doped structure; The second light-emitting unit is located above the first tunnel junction and includes, from bottom to top, a second N-type layer, a second light-emitting layer, and a second P-type layer stacked in sequence. The first light-emitting unit and the second light-emitting unit are superimposed and connected by the first tunnel junction, and the first light-emitting unit, the first tunnel junction and the second light-emitting unit are grown in the same device at one time. The carbon atom concentration in the first tunnel junction is greater than 5E18 atoms / cm³. 3 .

2. The multi-junction monolithic light-emitting element according to claim 1, characterized in that: The first light-emitting unit comprises, from bottom to top, a first N-type layer, a first stress-relieving layer, a first light-emitting layer, a first electron-blocking layer, and a first P-type layer stacked in sequence.

3. The multi-junction monolithic light-emitting element according to claim 2, characterized in that: The first light-emitting unit further includes a first P-type contact layer located above the first P-type layer, and the first tunnel junction is located above the first P-type contact layer; the thickness of the first P-type contact layer is greater than or equal to 1 nanometer and less than or equal to 10 nanometers.

4. The multi-junction monolithic light-emitting element according to claim 1, characterized in that: The thickness of the first tunnel junction is greater than or equal to 2 nanometers and less than or equal to 20 nanometers.

5. The multi-junction monolithic light-emitting element according to claim 1, characterized in that: The first tunnel junction is made of unintentionally doped gallium nitride or unintentionally doped indium gallium nitride.

6. The light-emitting element according to claim 1, characterized in that: The second light-emitting unit comprises, from bottom to top, a second N-type layer, a second stress-relieving layer, a second light-emitting layer, a second electron-blocking layer, and a second P-type layer stacked sequentially; the second N-type layer is made of N-type doped gallium nitride with a doping concentration of 5E18 Atoms / cm³. 3 Up to 5E20Atoms / cm 3 The thickness of the second N-type layer is greater than or equal to 2 nanometers and less than or equal to 300 nanometers; the thickness of the first N-type layer is greater than or equal to the thickness of the second N-type layer.

7. The multi-junction monolithic light-emitting element according to claim 6, characterized in that: The second light-emitting unit further includes a first N-type contact layer, located above the first tunnel junction and below the second N-type layer.

8. The multi-junction monolithic light-emitting element according to claim 7, characterized in that: The first N-type contact layer is made of N-type doped gallium nitride or indium gallium nitride, with a doping concentration of 5E19 atmos / cm³. 3 Up to 5E21Atoms / cm 3 The thickness of the first N-type contact layer is greater than or equal to 2 nanometers and less than or equal to 50 nanometers; the thickness of the first tunnel junction is greater than the thickness of the first N-type contact layer.

9. The multi-junction monolithic light-emitting element according to claim 1, characterized in that: The multi-junction monolithic light-emitting element further includes a substrate, on one side surface of which the first light-emitting unit, the first tunnel junction and the second light-emitting unit are stacked sequentially from bottom to top, and an undoped layer is also included between the substrate and the first light-emitting unit.

10. The multi-junction monolithic light-emitting element according to claim 9, characterized in that: The substrate is one of sapphire substrate, silicon substrate, and silicon carbide substrate; the undoped layer is gallium nitride that is not intentionally doped.

11. A multi-junction monolithic light-emitting element, characterized in that, At least including: The first light-emitting unit comprises, from bottom to top, a first N-type layer, a first light-emitting layer, and a first P-type layer stacked in sequence. The first tunnel junction, located above the first light-emitting unit, is an unintentionally doped structure; The second light-emitting unit is located above the first tunnel junction and includes, from bottom to top, a second N-type layer, a second light-emitting layer, and a second P-type layer stacked in sequence. The second tunnel junction, located above the second light-emitting unit, is an unintentionally doped structure; The third light-emitting unit is located above the second tunnel junction and includes, from bottom to top, a third N-type layer, a third light-emitting layer, and a third P-type layer stacked in sequence. The first light-emitting unit and the second light-emitting unit are superimposed and connected by current through the first tunnel junction, and the second light-emitting unit and the third light-emitting unit are superimposed and connected by current through the second tunnel junction. The first light-emitting unit, the first tunnel junction, the second light-emitting unit, the second tunnel junction and the third light-emitting unit are grown in the same device in one go.

12. A light-emitting device, comprising: substrate; A light-emitting element is mounted on the substrate, wherein the light-emitting element is a multi-junction monolithic light-emitting element as described in any one of claims 1 to 11.

13. A method for manufacturing a multi-junction monolithic light-emitting element, characterized in that, The manufacturing method includes the following steps: A substrate is provided, on which a first light-emitting unit is grown. The first light-emitting unit includes, from bottom to top, a first N-type layer, a first stress-relieving layer, a first light-emitting layer, a first electron-blocking layer, a first P-type layer, and a first P-type contact layer stacked in sequence. A first tunnel junction is grown above the first P-type contact layer to form an interruption layer; A first N-type contact layer is grown above the first tunnel junction; A second light-emitting unit is formed on the first N-type contact layer. The second light-emitting unit includes, from bottom to top, a second N-type layer, a second stress-relieving layer, a second light-emitting layer, a second electron-blocking layer, a second P-type layer, and a second P-type contact layer stacked in sequence, thereby forming a multi-junction monolithic light-emitting element.

14. The method for manufacturing a multi-junction monolithic light-emitting element according to claim 13, characterized in that: The first light-emitting unit, the first tunnel junction, and the second light-emitting unit are grown in the same device in a single process.

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