LED, optical communication device and optical communication system

Abstract

The invention provides an LED which is applied to the field of LEDs or the field of optical communication. The LED includes a P-type semiconductor layer, an active layer, and an N-type semiconductor layer. The active layer is located between the P-type semiconductor layer and the N-type semiconductor layer. The active layer comprises M barrier layers and M-1 well layers. The barrier layers and the well layers are alternately distributed. M is an integer greater than 1. And each barrier layer in the M barrier layers is a P-type doped layer. The sum of the doping concentration of N first barrier layers, close to the N-type semiconductor layer, in the M barrier layers is larger than the sum of the doping concentration of N second barrier layers, close to the P-type semiconductor layer, in the M barrier layers. When M is an even number, N = M / 2; and when M is an odd number, N = M / 2-1 / 2. In the technical scheme provided by the invention, the bandwidth of the LED can be improved by controlling the P-type doping concentration of the M barrier layers, so that the optical communication efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of LEDs or optical communication, and particularly to light emitting diodes (LEDs), LED arrays, optical communication devices, and optical communication systems. Background Art

[0002] For short-distance data communication, electrical interconnection is generally used. For example, copper cables are used for short-distance interconnection within 10 meters in a data center, metal wires are used for communication on a printed circuit board (PCB), and metal interconnection is also used between chips. With the rapid development of technologies such as the Internet, cloud computing, edge computing, and artificial intelligence (AI), the communication bandwidth required for short-distance scenarios such as 10-meter interconnection in a data center, interconnection on a PCB, and interconnection between chips has increased sharply. Optical interconnection has absolute advantages over electrical interconnection in terms of performance such as rate and transmission distance. Replacing electrical interconnection with optical interconnection has become the mainstream trend in short-distance communication scenarios. In optical interconnection, a laser is generally used as the light source of the transmitter. However, lasers have problems such as high threshold current, high power consumption, poor performance at high temperatures, and high costs. By using Micro-LED as the light source, it is beneficial to realize an optical communication system with low power consumption, low cost, wide-temperature operation, and high reliability. However, the bandwidth of Micro-LED is relatively low, which reduces the efficiency of optical communication. Summary of the Invention

[0003] This application provides an LED, an LED array, an optical communication device, and an optical communication system. By controlling the P-type doping concentration of M barrier layers, the bandwidth of the LED can be increased, thereby improving the efficiency of optical communication.

[0004] In a first aspect of this application, an LED is provided. The LED includes a P-type semiconductor layer, an active layer, and an N-type semiconductor layer. The active layer is located between the P-type semiconductor layer and the N-type semiconductor layer. The active layer includes M barrier layers and M - 1 well layers. The barrier layers and the well layers are alternately distributed. M is an integer greater than 1. Each of the M barrier layers is a P-type doped layer. The sum of the doping concentrations of N first barrier layers among the M barrier layers close to the N-type semiconductor layer is greater than the sum of the doping concentrations of N second barrier layers among the M barrier layers close to the P-type semiconductor layer. When M is an even number, N = M / 2; when M is an odd number, N = M / 2 - 1 / 2.

[0005] In this application, by performing P-type doping on each barrier layer, the number of carriers in the active layer can be increased. Moreover, by controlling the distribution of the P-type doping concentration in the M barrier layers, it is beneficial to improve the uniformity of the carrier distribution in the active region and the transport of carriers in the multiple quantum wells, thereby increasing the bandwidth of the LED.

[0006] In an alternative embodiment of the first aspect, the P-type edge barrier layer is the barrier layer closest to the P-type semiconductor layer among the M barrier layers. The N-type edge barrier layer is the barrier layer closest to the N-type semiconductor layer among the M barrier layers. The target barrier layer is a non-edge barrier layer among the M barrier layers. The doping concentration of the barrier layers from the N-type edge barrier layer to the target barrier layer gradually increases. The doping concentration of the barrier layers from the target barrier layer to the P-type edge barrier layer gradually decreases. Through this design of the doping concentration distribution, it is beneficial to improve the uniformity of the carrier distribution in the active region, thereby improving the concentration matching of electrons and holes and improving the LED bandwidth.

[0007] In an alternative embodiment of the first aspect, M is equal to 6. In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the doping concentrations of the M barrier layers are C1, C2, C3, C4, C5, and C6 respectively, and C1 < C2 > C3 > C4 > C5 > C6.

[0008] In an alternative embodiment of the first aspect, in the direction from the N-type semiconductor layer to the P-type semiconductor layer, the doping concentrations of the M barrier layers gradually decrease. Through this design of the doping concentration distribution, the hole concentration in the quantum wells near the N side can be replenished, and the LED bandwidth can be improved.

[0009] In an alternative embodiment of the first aspect, M is equal to 6. In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the doping concentrations of the M barrier layers are C1, C2, C3, C4, C5, and C6 respectively, and C1 > C2 > C3 > C4 > C5 > C6.

[0010] In an alternative embodiment of the first aspect, the doping concentrations of the X barrier layers close to the N-type semiconductor layer among the M barrier layers are the same. The doping concentrations of the Y barrier layers close to the P-type semiconductor layer among the M barrier layers are the same. The doping concentration of each of the X barrier layers is greater than the doping concentration of each of the Y barrier layers. M is equal to the sum of X and Y. Through this design of the doping concentration distribution, the difficulty of LED epitaxy can be reduced while improving the LED bandwidth.

[0011] In an alternative embodiment of the first aspect, M is equal to 6. In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the doping concentrations of the M barrier layers are C1, C2, C3, C4, C5, and C6 respectively, and C1 = C2 = C3 > C4 = C5 = C6.

[0012] In an alternative embodiment of the first aspect, the doping concentrations of X barrier layers among the M barrier layers that are closer to the N-type semiconductor layer are the same. The doping concentrations of Y barrier layers among the M barrier layers that are closer to the P-type semiconductor layer are the same. Among the M barrier layers, excluding the X barrier layers and the Y barrier layers, the doping concentrations of Z barrier layers are the same. The doping concentrations of Z barrier layers among the M barrier layers are the same. The doping concentration of the barrier layers in the X barrier layers is greater than the doping concentration of the barrier layers in the Z barrier layers. The doping concentration of the barrier layers in the Z barrier layers is greater than the doping concentration of the barrier layers in the Y barrier layers. M is equal to the sum of X, Y, and Z. Through this design of the doping concentration distribution, the difficulty of epitaxial control of the LED can be reduced.

[0013] In an alternative embodiment of the first aspect, M is equal to 6. In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the doping concentrations of the M barrier layers are C1, C2, C3, C4, C5, and C6 respectively, and C1 = C2 > C3 = C4 > C5 = C6.

[0014] In an alternative embodiment of the first aspect, the doping concentration of the barrier layer with the highest doping concentration among the M barrier layers ranges from 1×10 18 to 1×10 21 per cubic centimeter. The doping concentration of the barrier layer with the lowest doping concentration among the M barrier layers ranges from 1×10 16 to 1×10 18 per cubic centimeter.

[0015] In an alternative embodiment of the first aspect, the sum of the thicknesses of K first barrier layers and K first well layers among the M barrier layers and M - 1 well layers that are closer to the N-type semiconductor is greater than the sum of the thicknesses of K second barrier layers and K second well layers that are closer to the P-type semiconductor. When M is an even number, K = M / 2 - 1. When M is an odd number, K = M / 2 - 1 / 2. The thicknesses of the barrier layers and well layers closer to the P side are less than those closer to the N side, which is beneficial to increasing the density of carriers in the quantum wells closer to the P side and also helps to improve the transport characteristics of carriers in the multiple quantum wells, especially the injection and transport of hole carriers, thereby improving the bandwidth of the LED.

[0016] In an alternative embodiment of the first aspect, the thicknesses of the M - 1 well layers are the same, and the thicknesses of the M barrier layers are different.

[0017] In an alternative embodiment of the first aspect, the thicknesses of the K first barrier layers are the same. The thicknesses of the K second barrier layers are the same, and the thickness of the first barrier layer is greater than that of the second barrier layer.

[0018] In an alternative embodiment of the first aspect, the M barrier layers include X first barrier layers and Y second barrier layers, M is equal to the sum of X and Y, the thicknesses of the X first barrier layers are the same, the thicknesses of the Y second barrier layers are the same, and the thickness of the first barrier layer is greater than that of the second barrier layer.

[0019] In an alternative embodiment of the first aspect, the M barrier layers have the same thickness, and the M - 1 well layers have different thicknesses.

[0020] In an alternative embodiment of the first aspect, the K first well layers have the same thickness, the K second well layers have the same thickness, and the thickness of the first well layer is greater than that of the second well layer.

[0021] In an alternative embodiment of the first aspect, the M - 1 well layers include X - 1 first well layers and Y second well layers, M is equal to the sum of X and Y, the X - 1 first well layers have the same thickness, the Y second well layers have the same thickness, and the thickness of the first well layer is greater than that of the second well layer.

[0022] In an alternative embodiment of the first aspect, the M barrier layers have different thicknesses, and the M - 1 well layers have different thicknesses.

[0023] In an alternative embodiment of the first aspect, the M barrier layers include X first barrier layers and Y second barrier layers, M is equal to the sum of X and Y, the X first barrier layers have the same thickness, the Y second barrier layers have the same thickness, and the thickness of the first barrier layer is greater than that of the second barrier layer.

[0024] In an alternative embodiment of the first aspect, the M - 1 well layers include X - 1 first well layers and Y second well layers, M is equal to the sum of X and Y, the X - 1 first well layers have the same thickness, the Y second well layers have the same thickness, and the thickness of the first well layer is greater than that of the second well layer.

[0025] The second aspect of the present application provides an LED array. The LED array includes another LED and the LED described in the first aspect or any one of the first aspects, and the another LED and the LED share the same substrate.

[0026] The third aspect of the present application provides an optical communication device. The optical communication device includes the LED described in the first aspect or any one of the first aspects or the LED array described in the second aspect. The optical communication device further includes a processing circuit. The processing circuit is configured to transmit an electrical signal to the LED or the LED array. The LED or the LED array is configured to generate an optical signal according to the electrical signal.

[0027] In an alternative embodiment of the third aspect, the optical communication device further includes an optical coupling structure, and the optical coupling structure is configured to reduce the divergence angle of the LEDs in the LED or the LED array.

[0028] In an alternative embodiment of the third aspect, the optical communication device further includes a photodetector (PD). The PD or PD array is configured to receive another optical signal and convert the another optical signal into another electrical signal, and the processing circuit is configured to receive the another electrical signal.

[0029] In an alternative embodiment of the third aspect, the optical communication device further includes another optical coupling structure, and the another optical coupling structure is configured to condense the another optical signal. The PD or PD array is configured to convert the condensed another optical signal into another electrical signal.

[0030] The fourth aspect of the present application provides an optical communication system. The optical communication system includes another optical communication device and the optical communication device described in the third aspect or any one of the embodiments of the third aspect. The optical communication device and the another optical communication device are connected by an optical fiber or an optical waveguide. The optical communication device is configured to transmit an optical signal to the another optical communication device. Description of the Drawings

[0031] Figure 1a The first schematic structural diagram of the LED provided by the embodiment of the present application;

[0032] Figure 1b The second schematic structural diagram of the LED provided by the embodiment of the present application;

[0033] Figure 2 Schematic diagram of the relationship between the bandwidth and the injection current density of the LED under different P-type doping concentrations calculated according to the LED bandwidth formula;

[0034] Figure 3a Schematic diagram of the concentration distribution of electrons in the multi-quantum well active region;

[0035] Figure 3b Schematic diagram of the concentration distribution of hole carriers in the multi-quantum well active region;

[0036] Figure 4 The third schematic structural diagram of the LED provided by the embodiment of the present application;

[0037] Figure 5 Schematic diagram of the simulation of the bandwidth of the LED with undoped active region barriers provided by the embodiment of the present application;

[0038] Figure 6 Schematic diagram of the simulation of the bandwidth of the LED with the first exemplary doping provided by the embodiment of the present application;

[0039] Figure 7 Schematic diagram of the simulation of the bandwidth of the LED with the second exemplary doping provided by the embodiment of the present application;

[0040] Figure 8Schematic diagram of the bandwidth simulation of the LED doped with the third example provided by the embodiment of the present application;

[0041] Figure 9a The fourth structural schematic diagram of the LED provided by the embodiment of the present application;

[0042] Figure 9b The fifth structural schematic of the LED provided by the embodiment of the present application;

[0043] Figure 9c The sixth structural schematic of the LED provided by the embodiment of the present application;

[0044] Figure 9d The seventh structural schematic of the LED provided by the embodiment of the present application;

[0045] Figure 9e The eighth structural schematic of the LED provided by the embodiment of the present application;

[0046] Figure 9f The ninth structural schematic of the LED provided by the embodiment of the present application;

[0047] Figure 9g The tenth structural schematic of the LED provided by the embodiment of the present application;

[0048] Figure 10 The structural schematic diagram of the epitaxial wafer provided by the embodiment of the present application;

[0049] Figure 11 The eleventh structural schematic diagram of the LED provided by the embodiment of the present application;

[0050] Figure 12 The structural schematic diagram of the LED array provided by the embodiment of the present application;

[0051] Figure 13 The first structural schematic diagram of the optical communication device provided by the embodiment of the present application;

[0052] Figure 14 The second structural schematic diagram of the optical communication device provided by the embodiment of the present application;

[0053] Figure 15 The third structural schematic diagram of the optical communication device provided by the embodiment of the present application;

[0054] Figure 16 The fourth structural schematic diagram of the optical communication device provided by the embodiment of the present application;

[0055] Figure 17 The fifth structural schematic diagram of the optical communication device provided by the embodiment of the present application;

[0056] Figure 18Schematic diagram of the optical communication system provided by the embodiment of the present application. Detailed implementation manners

[0057] The present application provides an LED, an LED array, an optical communication device, and an optical communication system. By controlling the P-type doping concentration of M barrier layers, the bandwidth of the LED can be increased, thereby improving the efficiency of optical communication. It should be understood that the "first", "second", or "target", etc. used in the present application are only for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying an order. In addition, for the sake of simplicity and clarity, repeated reference numerals and / or letters are used in multiple drawings of the present application. The repetition does not indicate a strict limitation relationship between various embodiments and / or configurations.

[0058] The LED provided by the present application is applied to the field of LEDs and / or the field of optical communication. In the field of optical communication, electrical interconnection is generally used for short-distance data communication. Optical interconnection has absolute advantages over electrical interconnection in terms of performance such as rate and transmission distance. Replacing electrical interconnection with optical interconnection has become the mainstream trend in short-distance communication scenarios. In optical interconnection, a laser is generally used as the light source of the transmitter. Lasers have problems such as high threshold current, high power consumption, poor performance at high temperatures, and high costs. By using Micro-LED as the light source, it is beneficial to realize an optical communication system with low power consumption, low cost, wide-temperature operation, and high reliability. However, the bandwidth of Micro-LED is relatively low, which reduces the efficiency of optical communication.

[0059] Therefore, the present application provides an LED. Figure 1a The first schematic diagram of the LED provided by the embodiment of the present application. As Figure 1a shown, the LED includes a P-type semiconductor layer 101, an active layer 102, and an N-type semiconductor layer 103. The P-type semiconductor layer 101 is also referred to as the P-type layer 101. The N-type semiconductor layer 103 is also referred to as the N-type layer 103. The active layer 102 is located between the P-type semiconductor layer 101 and the N-type semiconductor layer 103. The active layer 102 includes M barrier layers and M - 1 well layers. The barrier layers and the well layers are alternately distributed. M is an integer greater than 1. In Figure 1a the example, the active layer 102 includes 3 barrier layers and 2 well layers. Each of the M barrier layers is a P-type doped layer. The dopant of the P-type doped layer can be magnesium (Mg). The sum of the doping concentrations of the N first barrier layers in the M barrier layers close to the N-type semiconductor layer 103 is greater than the sum of the doping concentrations of the N second barrier layers in the M barrier layers close to the P-type semiconductor layer 101. When M is an even number, N = M / 2; when M is an odd number, N = M / 2 - 1 / 2. Figure 1b The second schematic diagram of the LED provided by the embodiment of the present application. As Figure 1b shown, when M is equal to 6, the M barrier layers include 3 first barrier layers and 3 second barrier layers.

[0060] According to the ABC model of LED recombination, the internal quantum efficiency of an LED can be expressed as:

[0061]

[0062] Where IQE is the internal quantum efficiency of the LED, A is the Shockley-Read-Hall (SRH) recombination coefficient related to defects, B is the radiative recombination coefficient, C is the Auger recombination coefficient, and n is the carrier density. The differential carrier lifetime μ of the LED is:

[0063]

[0064] The bandwidth f of the LED 3dB is inversely proportional to the carrier lifetime:

[0065] τ -1 = 2πf 3dB = A + 2Bn + 3Cn 2

[0066] It can be seen from the above formula that increasing the SRH recombination coefficient A, the radiative recombination coefficient B, the Auger recombination coefficient C, and the carrier density n can all increase the bandwidth of the LED. Also, as the injection current density n increases, the bandwidth of the LED will also increase. When operating at low currents, the current density n in the active region of the LED is very low, resulting in a limited bandwidth of the LED at low currents. To increase the bandwidth of the LED operating at low currents, doping can be carried out in the active region of the LED to provide background carriers and increase the value of n. For GaN-based LEDs, due to the difficulty of P-type doping and the high P-type activation energy, the hole concentration in the device is much lower than the electron concentration. Therefore, P-type doping can be preferentially selected for doping in the quantum well. Figure 2 is a schematic diagram of the relationship between the bandwidth and injection current density of the LED calculated according to the LED bandwidth formula at different P-type doping concentrations of the barrier layer. Figure 2 The abscissa of 2 . Figure 2 is the current density, with the unit of amperes per square centimeter A / cm 18 . When the barrier layer of the quantum well is not doped, the relationship between the bandwidth and injection current density of the LED is curve 201. When the P-type doping concentration of the quantum well barrier layer is 1×10 19 per cubic centimeter, the relationship between the bandwidth and injection current density of the LED is curve 202. When the P-type doping concentration of the quantum well barrier layer is 5×10 20When it is per cubic centimeter, the relationship between the bandwidth of the LED and the injection current density is curve 204. According to Figure 2 It can be known that by performing P-type doping on the quantum well barrier layer, the bandwidth of the LED can be effectively improved, especially at low currents. When the P-type doping concentration reaches 10 19 per cubic centimeter, at low current densities, the bandwidth of the LED is significantly improved and can reach 1 GHz. In the case of high currents, the bandwidth of the LED can reach 3 GHz.

[0067] On the other hand, GaN-based LEDs have problems of carrier mismatch and uneven carrier distribution. Figure 3a is the concentration distribution diagram of electrons in the multi-quantum well active region. Figure 3b is the concentration distribution diagram of hole carriers in the multi-quantum well active region. Figure 3a and Figure 3b The abscissa in is the distance from the N-type layer 103. Figure 3a and Figure 3b The ordinate in and is the logarithm of the electron concentration and the hole concentration. The unit is Log (electron concentration / cm 3 ) and Log (hole concentration / cm 3 ). As shown in Figure 3a and Figure 3b , under low current injection of 500 A / cm 2 , since the P-type doping efficiency of GaN is much lower than the N-type doping efficiency, and the mobility of holes is lower than that of electrons, the hole concentration (15th to 18th power) injected into the quantum well is one to two orders of magnitude lower than the electron concentration (17.5th to 18.5th power). As shown in Figure 3a and Figure 3b , the distribution of electrons in the multi-quantum well is more uniform. Compared with the distribution of electrons, the distribution of holes in the multi-quantum well is more uneven, and there is a characteristic that the concentration of holes in the N-side quantum well is low and the concentration of holes in the P-side quantum well is high. Therefore, in the embodiments of the present application, the P-type doping concentration in the region close to the N side is higher than the P-type doping concentration in the region close to the P side. By controlling the distribution of the P-type doping concentration, the hole concentration in the quantum well close to the N side can be supplemented, and a more uniform carrier distribution and more matched electron and hole concentrations can be achieved to improve the bandwidth of the LED.

[0068] According to the description above Figure 1a , the sum of the doping concentrations of the N first barrier layers in the M barrier layers close to the N-type semiconductor layer 103 is greater than the sum of the doping concentrations of the N second barrier layers in the M barrier layers close to the P-type semiconductor layer 101. Hereinafter, M is taken as 6 for description. Figure 4 is the third structural schematic diagram of the LED provided by the embodiments of the present application. As shown in Figure 4As shown, the LED includes an N-type layer 103, a P-type layer 101, and an active layer located between the N-type layer 103 and the P-type layer 101. The active layer includes six barrier layers. The doping concentrations of the six barrier layers are C1, C2, C3, C4, C5, and C6 respectively. C1 + C2 + C3 > C4 + C5 + C6. This application provides several different distribution designs of doping concentrations. Taking M equal to 6 as an example, the following describes them separately.

[0069] In the first example, the P-type edge barrier layer is the barrier layer closest to the P-type semiconductor layer among the M barrier layers. The N-type edge barrier layer is the barrier layer closest to the N-type semiconductor layer among the M barrier layers. The target barrier layer is the non-edge barrier layer among the M barrier layers. The doping concentration of the barrier layers from the N-type edge barrier layer to the target barrier layer gradually increases. The doping concentration of the barrier layers from the target barrier layer to the P-type edge barrier layer gradually decreases. For example, when the value of C3 is the largest among the doping concentrations of the M barrier layers, C1 < C2 < C3 > C4 > C5 > C6. When the value of C2 is the largest among the doping concentrations of the M barrier layers, C1 < C2 > C3 > C4 > C5 > C6. For example, the doping concentration range of C1 is between 4.5×10 19 and 5.5×10 19 per cubic centimeter; the doping concentration range of C2 is between 0.5×10 20 and 1.5×10 20 per cubic centimeter; the doping concentration range of C3 is between 4.5×10 19 and 5.5×10 19 per cubic centimeter; the doping concentration range of C4 is between 0.5×10 19 and 1.5×10 19 per cubic centimeter; the doping concentration range of C5 is between 4.5×10 18 and 5.5×10 18 per cubic centimeter; the doping concentration range of C6 is between 0.5×10 18 and 1.5×10 18 per cubic centimeter.

[0070] Figure 5 It is a simulation schematic diagram of the bandwidth of the LED with undoped barrier layers in the active region provided by the embodiment of this application. Figure 5 The abscissa of Figure 5 is the bandwidth, and the unit is GHz. Figure 5 The ordinate of 2 is the responsivity, and the unit is decibel dB. As Figure 6 shown, at a low current density of 500 A / cm Figure 6 the 3 dB modulation bandwidth of the LED with undoped barrier layers is only 0.84 GHz. Figure 6 It is a simulation schematic diagram of the bandwidth of the LED doped with the first example provided by the embodiment of this application. As Figure 6 shown, at 500 A / cm2 At a low current density, the 3dB modulation bandwidth of the LED doped with the first example is 1.51 GHz. Compared with the Figure 5 modulation bandwidth of the LED in

[0071] In the second example, in the direction from the N-type semiconductor layer 103 to the P-type semiconductor layer 101, the doping concentration of the M barrier layers gradually decreases. At this time, C1 > C2 > C3 > C4 > C5 > C6. For example, the doping concentration range of C1 is between 4.5×10 20 and 5.5×10 20 per cubic centimeter; the doping concentration range of C2 is between 0.5×10 20 and 1.5×10 20 per cubic centimeter; the doping concentration range of C3 is between 4.5×10 19 and 5.5×10 19 per cubic centimeter; the doping concentration range of C4 is between 0.5×10 19 and 1.5×10 19 per cubic centimeter; the doping concentration range of C5 is between 4.5×10 18 and 5.5×10 18 per cubic centimeter; the doping concentration range of C6 is between 0.5×10 18 and 1.5×10 18 per cubic centimeter.

[0072] Figure 7 is a simulation schematic diagram of the bandwidth of the LED doped with the second example provided by the embodiment of the present application. As Figure 7 shown, at a low current density of 500 A / cm 2 , the 3dB modulation bandwidth of the LED doped with the second example is 1.34 GHz. Compared with the Figure 5 modulation bandwidth of the LED in

[0073] In the third example, the doping concentration of the X barrier layers close to the N-type semiconductor layer 103 in the M barrier layers is the same. The doping concentration of the Y barrier layers close to the P-type semiconductor layer 101 in the M barrier layers is the same. The doping concentration of the barrier layers in the X barrier layers is greater than the doping concentration of the barrier layers in the Y barrier layers. M is equal to the sum of X and Y. For example, C1 = C2 = C3 > C4 = C5 = C6. The doping concentration range of C1, C2, and C3 is between 4.5×10 19 and 5.5×10 19 per cubic centimeter; the doping concentration range of C4, C5, and C6 is between 0.5×10 18 and 1.5×10 18 per cubic centimeter.

[0074] Figure 8 This is a simulation schematic diagram of the bandwidth of an LED doped with a third exemplary doping provided by an embodiment of the present application. As Figure 8 shown, at a low current density of 500 A / cm 2 , the 3 dB modulation bandwidth of the LED doped with the third exemplary doping is 1.46 GHz. Compared with the modulation bandwidth of the LED in Figure 5 , it is increased by 0.62 GHz.

[0075] In the fourth example, the doping concentrations of X barrier layers among the M barrier layers close to the N-type semiconductor layer 103 are the same. The doping concentrations of Y barrier layers among the M barrier layers close to the P-type semiconductor layer 101 are the same. The doping concentrations of the other Z barrier layers among the M barrier layers are the same. The doping concentration of the barrier layers in the X barrier layers is greater than that of the barrier layers in the Z barrier layers. The doping concentration of the barrier layers in the Z barrier layers is greater than that of the barrier layers in the Y barrier layers. M is equal to the sum of X, Y, and Z. For example, C1 = C2 > C3 = C4 > C5 = C6. The doping concentration range of C1 and C2 is between 4.5×10 19 and 5.5×10 19 per cubic centimeter; the doping concentration range of C3 and C4 is between 0.5×10 19 and 1.5×10 19 per cubic centimeter; the doping concentration range of C5 and C6 is between 4.5×10 18 and 5.5×10 18 per cubic centimeter.

[0076] According to the foregoing Figure 2 description, the bandwidth of the LED can be improved by P-type doping of the barrier layers in the active region. In practical applications, there is a preferred range for the maximum and minimum values of the doping concentration. The preferred range of the highest doping concentration among the M barrier layers is between 1×10 18 and 1×10 20 per cubic centimeter, and the preferred range of the lowest doping concentration among the M barrier layers is between 1×10 16 and 1×10 18 per cubic centimeter.

[0077] In practical applications, the thicknesses of the well layers and barrier layers in the active layer also affect the density, transport, and matching of carriers, thereby affecting the bandwidth of the LED. The LED active layer includes M barrier layers and M - 1 well layers. The sum of the thicknesses of K first well layers and K first barrier layers among all the barrier layers and well layers close to the N-type semiconductor layer 103 is greater than the sum of the thicknesses of K second barrier layers and K second well layers close to the P-type semiconductor layer 101. When M is an even number, K = M / 2 - 1; when M is an odd number, K = M / 2 - 1 / 2. Figure 9aThis is the fourth structural schematic diagram of the LED provided by the embodiments of the present application. The embodiments of the present application are described by taking M = 6 as an example. As Figure 9a shown, the LED includes an N-type layer 103, a P-type layer 101, and an active layer located between the N-type layer 103 and the P-type layer 101. The active layer includes six barrier layers and five well layers. The thicknesses of the six barrier layers are d1, d2, d3, d4, d5, and d6 respectively. The thicknesses of the five well layers are D1, D2, D3, D4, and D5 respectively. The thickness of a well layer or a barrier layer refers to the length of the well layer or the barrier layer in the first direction. The first direction refers to the light-emitting direction or the light-emitting opposite direction of the LED. In Figure 9a the example of, d1 + d2 + d3 + D1 + D2 > d4 + d5 + d6 + D4 + D5. The present application provides several different distribution designs of the well-barrier layer thicknesses. The following describes them separately by taking M equal to 6 as an example.

[0078] In the first method, the thicknesses of M - 1 well layers are the same, and the thicknesses of M barrier layers are different. At this time, D1 = D2 = D3 = D4 = D5. The different thicknesses of the M barrier layers mean that there are barrier layers with different thicknesses among the M barrier layers. For example, d1 > d2 > d3 > d4 > d5 > d6. The M barrier layers may include barrier layers with the same thickness. For example, d1 = d2 > d3 > d4 > d5 > d6. In practical applications, in order to improve the injection and transport of holes, the thickness of the barrier layer close to the P side can be reduced. The thicknesses of K first barrier layers are the same, and the thicknesses of K second barrier layers are the same. The thickness of the first barrier layer is greater than the thickness of the second barrier layer. At this time, d1 = d2 = d3 > d4 = d5 = d6. Figure 9b This is the fifth structural schematic of the LED provided by the embodiments of the present application. As Figure 9b shown, D1 = D2 = D3 = D4 = D5, d1 = d2 = d3 > d4 = d5 = d6. For example, D1 is equal to 2 nanometers. The P-type layer 101 includes a P-ALGaN EBL electron blocking layer 901 and a P-GaN layer 902. It should be understood that in practical applications, the P-type layer 101 may further include a P + -GaN contact layer. The P-GaN layer 902 is located between the P-ALGaN EBL electron blocking layer 901 and the P + -GaN contact layer.

[0079] In the second method, the thicknesses of the M barrier layers are the same, and the thicknesses of the M - 1 well layers are different. At this time, d1 = d2 = d3 = d4 = d5 = d6. The fact that the thicknesses of the M - 1 well layers are different means that there are well layers with different thicknesses among the M - 1 well layers. For example, D1 > D2 > D3 > D4 > D5. The M - 1 well layers may include well layers with the same thickness. For example, D1 = D2 > D3 > D4 > D5. In practical applications, in order to increase the carrier density in the quantum wells near the P side and increase the spatial overlap of the electron and hole wave functions, the thickness of the well layers can be reduced. The M - 1 well layers include X - 1 first well layers and Y second well layers. M is equal to the sum of X and Y. The thicknesses of the X - 1 first well layers are the same. The thicknesses of the Y second well layers are the same. The thickness of the first well layer is greater than the thickness of the second well layer. For example, D1 = D2 > D3 = D4 = D5. Figure 9c The sixth structural schematic diagram of the LED provided by the embodiment of the present application is as follows. Figure 9c As shown, d1 = d2 = d3 = d4 = d5 = d6, D1 = D2 > D3 = D4 = D5. For example, D1 is equal to 3 nanometers, and D3 is equal to 1.5 nanometers.

[0080] In the third method, the thicknesses of the M barrier layers are different, and the thicknesses of the M - 1 well layers are different. The thicknesses of the K first barrier layers are the same. The thicknesses of the K second barrier layers are the same. The thickness of the first barrier layer is greater than the thickness of the second barrier layer. The thicknesses of the first well layers between the K first barrier layers are the same. The thicknesses of the second well layers between the K second barrier layers are the same. The thickness of the first well layer is greater than the thickness of the second well layer. At this time, d1 = d2 = d3 > d4 = d5 = d6. D1 = D2 > D4 = D5. Figure 9d The seventh structural schematic diagram of the LED provided by the embodiment of the present application is as follows. Figure 9d As shown, d1 = d2 = d3 > d4 = d5 = d6. D1 = D2 > D3 = D4 = D5. In this design, the barrier layer near the P side is thinner, the injection and transport of holes are better, and at the same time, the well layer near the P side is also thinner, the carrier density in the quantum well is higher, and the spatial overlap of the electron and hole wave functions is more, which is beneficial to improving the radiative recombination efficiency and modulation rate of the LED.

[0081] It should be understood that in the embodiment of the present application, the P - type doping concentration of the barrier layer in the LED and the thicknesses of the well layers and barrier layers in the active layer can be controlled simultaneously, so as to increase the bandwidth of the LED. For example, Figure 9e The eighth structural schematic diagram of the LED provided by the embodiment of the present application is as follows. In the Figure 9e LED, D1 = D2 = D3 = D4 = D5, d1 = d2 = d3 > d4 = d5 = d6, C1 < C2 > C3 > C4 > C5 > C6. Another example is Figure 9f The ninth structural schematic diagram of the LED provided by the embodiment of the present application is as follows. In theFigure 9f In the LED, d1 = d2 = d3 = d4 = d5 = d6, D1 = D2 > D3 = D4 = D5, C1 < C2 > C3 > C4 > C5 > C6. For another example, Figure 9g This is the tenth structural schematic diagram of the LED provided by the embodiment of the present application. In Figure 9g In the LED, d1 = d2 = d3 > d4 = d5 = d6. D1 = D2 > D3 = D4 = D5, C1 < C2 > C3 > C4 > C5 > C6. It should be understood that Figures 9e - 9g These are just several examples provided by the embodiment of the present application. In practical applications, the doping concentration of the stack layer can refer to the description in any of the foregoing Figures 4 - 8 figures.

[0082] Figure 10 This is the structural schematic diagram of the epitaxial wafer provided by the embodiment of the present application. As Figure 10 shown, the epitaxial wafer includes a substrate 1002, an undoped U-GaN layer 1001, an N-type semiconductor layer 103, an active layer 102, and a P-type semiconductor layer 101. The P-type semiconductor layer 101 includes a P-type electron blocking layer, a P-GaN layer, and a P + -GaN contact layer. The N-type semiconductor layer 103 includes an n-GaN layer and a superlattice layer. By bonding the epitaxial wafer and other chips and removing the substrate 1002 and the U-GaN layer, an LED with a flip-chip structure can be fabricated.

[0083] Figure 11 This is the eleventh structural schematic diagram of the LED provided by the embodiment of the present application. As Figure 11 shown, in Figure 1aBased on this, the LED includes, in sequence along the first direction, a substrate 1101, a lower electrode layer 1102, a P-type semiconductor layer 101, an active layer 102, an N-type semiconductor layer 103, a transparent upper electrode layer 1103, an upper reflection layer 1104, and a focusing layer 1105. The material of the substrate 1101 can be silicon, an integrated circuit chip, a silicon interposer, an organic substrate, a glass substrate, a sapphire substrate, etc. The substrate 1101 is used as a base and provides processing and control circuits. The lower electrode layer 1102 is located between the substrate 1101 and the P-type semiconductor layer 101. The material of the lower electrode layer 1102 can be a metal. The P-type semiconductor layer 101 is located between the lower electrode layer 1102 and the active layer 102. The material of the P-type semiconductor layer 101 can be GaN, etc. The active layer 102 is located between the P-type semiconductor layer 101 and the N-type semiconductor layer 103. The P-type semiconductor layer 101 is used to provide hole carriers, and the N-type semiconductor layer 103 is used to provide electron carriers. The active layer 102 can be a quantum well composed of gallium nitride (GaN) and indium gallium nitride (InGaN). The active layer 102 is used for radiative recombination according to hole carriers and electron carriers. The N-type semiconductor layer 103 is located between the active layer 102 and the transparent upper electrode layer 1103. The material of the N-type semiconductor layer 103 can be GaN, etc. The transparent upper electrode layer 1103 is located between the N-type semiconductor layer 103 and the upper reflection layer 1104. The transparent upper electrode layer 1103 can be a transparent conductive thin film. The material of the transparent upper electrode layer 1103 can be indium tin oxide, aluminum zinc oxide, etc. The light transmittance of the transparent upper electrode layer 1103 is greater than 0%. For example, in practical applications, the light transmittance of the transparent upper electrode layer 1103 to visible light is greater than 30%, 50%, 70%, or 90%. The upper reflection layer 1104 can be a distributed bragg reflection (DBR) reflection layer. The material of the upper reflection layer 1104 can be silicon dioxide, titanium dioxide, aluminum oxide, tantalum pentoxide, or a combination thereof. The upper reflection layer 1104 is used to reflect photons. The focusing layer 1105 is also called a spacer layer. The material of the focusing layer 1105 can be an insulating glue. A lens 1110 is provided on the focusing layer 1105 of the LED. The lens 1110 is used to adjust the divergence angle of the optical signal output by the LED and improve the coupling efficiency of the optical signal into the optical fiber or waveguide.

[0084] The LED further includes an isolation layer 1107 and a connection electrode 1109. A first electrode 1106 and a second electrode 1108 are disposed on the substrate 1101. The material of the isolation layer 1107 can be insulating glue. The material of the isolation layer 1107 can also be silicon dioxide, silicon nitride, etc. The isolation layer 1107 is used to isolate the connection between the connection electrode 1109 and the lower electrode layer 1102, the P-type semiconductor layer 101, the active layer 102, and the N-type semiconductor layer 103. The connection electrode 1109 is used to connect the transparent upper electrode layer 1103 and the second electrode 1108. The lower electrode layer 1102 is used to connect the first electrode 1106. In Figure 1a In the example of, the LED powers the transparent upper electrode layer 1103 through the second electrode 1108 on the substrate 1101, and powers the lower electrode layer 1102 through the first electrode 1106 on the substrate 1101.

[0085] It should be understood that Figure 11 This is only an example of the LED provided by the embodiments of the present application. In practical applications, those skilled in the art can make adaptive modifications to the structure of the LED according to requirements. For example, in Figure 11 , the positions of the P-type semiconductor layer 101 and the N-type semiconductor layer 103 are interchanged. At this time, the P-type semiconductor layer 101 is located between the active layer 102 and the transparent upper electrode layer 1103, and the N-type semiconductor layer 103 is located between the active layer 102 and the lower electrode layer 1102. Another example is that the lower electrode layer 1102 includes a lower reflective layer and a bonding metal layer. The lower reflective layer is located between the bonding metal layer and the P-type semiconductor layer 101. The bonding metal layer is between the substrate 1101 and the lower reflective layer.

[0086] In the embodiments of the present application, the LED can be a micro light emitting diode (Micro-LED) or a resonant cavity micro light emitting diode (Resonant cavity micro light emitting diode, RC Micro-LED). For example, the length of the P-type semiconductor layer 101 can be less than 100 microns. The length of the P-type semiconductor layer 101 can also be referred to as the lateral dimension of the P-type semiconductor layer 101 or the mesa size of the LED. When Figure 11 is a side view of the LED, the length of the P-type semiconductor layer 101 refers to the maximum dimension of the P-type semiconductor layer 101 in the top view of the LED. For example, when the shape of the P-type semiconductor layer 101 in the top view is circular, the length of the P-type semiconductor layer 101 refers to the diameter of the P-type semiconductor layer 101.

[0087] The embodiments of the present application further provide an LED array. The LED array includes another LED and the foregoing Figure 1a , Figure 1b , Figure 4 , Figures 9a - 9g or Figure 11The LED described in Figure 1a , Figure 1b , Figure 4 , Figures 9a - 9g or Figure 11 The LED described in. Another LED and the LED share the same substrate. Figure 12 is a schematic structural diagram of the LED array provided by the embodiment of the present application. As Figure 12 shown, the LED array includes two LEDs, namely LED 1201 and LED 1202. On the basis of Figure 11 , LED 1201 further includes an insulating layer 1204 and a planarizing layer 1205. The planarizing layer 1205 is used to fill the area between the substrate 1101 and the transparent upper electrode layer 1103. A part of the planarizing layer 1205 can be used as an isolation layer. For the description of LED 1202, reference can be made to the description of LED 1201. LED 1202 and LED 1201 share the substrate 1101. In the example of Figure 12 , LED 1202 and LED 1201 also share the upper reflective layer 1104 and the focusing layer 1105. A lens 1203 is provided on LED 1202. For the description of the lens 1203, reference can be made to the description of the lens 1110. It should be understood that the number of LEDs in the LED array is not limited to two, and according to application requirements, the number of LEDs can be extended to dozens, hundreds, thousands or more.

[0088] The embodiment of the present application also provides an optical communication device. Figure 13 is the first schematic structural diagram of the optical communication device provided by the embodiment of the present application. As Figure 13As shown, the optical communication device 1300 includes a processing circuit 1301 and an LED 1302. The optical communication device 1300 can also be referred to as an optical transmission module, an optical transceiver module, an optical module, an optical transmission device, an optical transmission end, an optical communication device, or an optical interconnection transceiver device, etc. The processing circuit 1301 can also be referred to as a logic circuit. The processing circuit 1301 can be a processor. For example, the processing circuit 1301 can be a central processing unit (CPU), a graphics processing unit (GPU), a neural network processing unit (NPU), a network processor (NP), or a combination of a CPU and an NP. The processing circuit 1301 can further include a hardware chip or other general-purpose processors. The above hardware chip can be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The processing circuit 1301 is used to transmit an electrical signal to the LED 1302. The LED 1302 is used to generate an optical signal according to the electrical signal. For the description of the LED 1302, reference can be made to the foregoing description of Figure 1a , Figure 1b , Figure 4 , Figures 9a - 9g or Figure 11 any one of the figures.

[0089] In practical applications, the optical communication device 1300 can include a processing circuit 1301 and an LED array. For the description of the LED array, reference can be made to the foregoing Figure 12 description. The processing circuit 1301 is used to transmit a plurality of electrical signals to the LED array. The LED array includes a plurality of LEDs. The plurality of LEDs and the plurality of electrical signals are in one-to-one correspondence. The plurality of LEDs are used to obtain a plurality of optical signals according to the plurality of electrical signals. The plurality of optical signals and the plurality of LEDs are in one-to-one correspondence.

[0090] Figure 14 This is the second structural schematic diagram of the optical communication device provided by the embodiment of the present application. As Figure 14 shown, in Figure 13On the basis of this, the optical communication device 1300 further includes a driving circuit 1401 and a lens 1402. The driving circuit 1401 is configured to receive an electrical signal from the processing circuit 1301 and obtain a driving electrical signal according to the electrical signal. The driving circuit 1401 is further configured to transmit the driving electrical signal to the LED 1302. The LED 1302 is configured to generate an optical signal according to the driving electrical signal and output the optical signal through the lens 1402. Regarding the positional relationship between the lens 1402 and the LED 1302, reference can be made to Figure 11 for the description.

[0091] Figure 15 This is the third structural schematic diagram of the optical communication device provided by the embodiment of the present application. As Figure 15 shown, on the basis of Figure 14 this, the optical communication device 1300 further includes a lens 1501, a PD 1502, an amplifying circuit 1503, and a processing circuit 1504. The lens 1501 is configured to receive another optical signal, adjust the divergence angle of the another optical signal, and focus the another optical signal onto the PD 1502. The PD 1502 is configured to convert the another optical signal into another electrical signal and transmit the electrical signal to the amplifying circuit 1503. The amplifying circuit 1503 can include a trans-impedance amplifier (TIA) and a limiting amplifier (LA). The amplifying circuit 1503 is configured to amplify the another electrical signal and transmit the amplified electrical signal to the processing circuit 1504. The processing circuit 1504 and the processing circuit 1301 can be the same processor. The processing circuit 1504 is configured to process the amplified electrical signal. In practical applications, in order to reduce the cost of the optical communication device 1300 or improve the integration degree of the optical communication device, the PD 1502 and the LED 1302 can be integrated on a substrate. At this time, the PD 1502 and the LED 1302 share the same substrate. The lens 1402, the LED 1302, the driving circuit 1401, and the lens 1501, the PD 1502, the amplifying circuit 1503 can be integrated on the same substrate. At this time, the lens 1402, the LED 1302, the driving circuit 1401, and the lens 1501, the PD 1502, the amplifying circuit 1503 share the same substrate. The lens 1402, the LED 1302, the driving circuit 1401, the processing circuit 1301, and the lens 1501, the PD 1502, the amplifying circuit 1503, the processing circuit 1504 can be integrated on the same substrate. At this time, the lens 1402, the LED 1302, the driving circuit 1401, the processing circuit 1301, and the lens 1501, the PD 1502, the amplifying circuit 1503, the processing circuit 1504 share the same substrate.

[0092] Figure 16 This is the fourth structural schematic diagram of the optical communication device provided by the embodiment of the present application. AsFigure 16 As shown, the optical communication device 1600 includes a processing circuit 1601, a plurality of driving circuits 1602, an LED array 1603, and a lens array 1604. For the description of the processing circuit 1601, reference can be made to the description of the processing circuit 1301 in the foregoing Figure 13 section. The processing circuit 1601 is used to generate a plurality of electrical signals. The plurality of driving circuits 1602 are used to generate a plurality of driving electrical signals according to the plurality of electrical signals. The plurality of driving circuits 1602 and the plurality of driving electrical signals are in one-to-one correspondence. The plurality of driving electrical signals and the plurality of electrical signals are in one-to-one correspondence. The LED array 1603 includes a plurality of LEDs. The plurality of LEDs are used to generate a plurality of optical signals according to the plurality of driving electrical signals. The plurality of LEDs and the plurality of optical signals are in one-to-one correspondence. The plurality of driving electrical signals and the plurality of optical signals are in one-to-one correspondence. The lens array 1604 includes a plurality of lenses. The plurality of lenses are used to adjust the divergence angles of the plurality of optical signals. The plurality of lenses and the plurality of optical signals are in one-to-one correspondence.

[0093] Figure 17 This is the fifth structural schematic diagram of the optical communication device provided by the embodiment of the present application. As Figure 17 shown, on the basis of Figure 16 , the optical communication device 1600 further includes a lens array 1701, a PD array 1702, an amplifier array 1703, and a processing circuit 1704. The lens array 1701 includes a plurality of lenses. The plurality of lenses are used to receive the plurality of optical signals and focus the plurality of optical signals onto the plurality of PDs of the PD array 1702. The plurality of optical signals and the plurality of lenses are in one-to-one correspondence. The plurality of optical signals and the plurality of PDs are in one-to-one correspondence. The plurality of PDs convert the plurality of optical signals into a plurality of electrical signals and transmit the plurality of electrical signals to the plurality of amplifier circuits in the amplifier array 1703. The plurality of electrical signals and the plurality of PDs are in one-to-one correspondence, and the plurality of electrical signals and the plurality of amplifier circuits are in one-to-one correspondence. The plurality of amplifier circuits are used to amplify the plurality of electrical signals to obtain a plurality of amplified electrical signals and transmit the plurality of amplified electrical signals to the processing circuit 1704. The plurality of amplified electrical signals and the plurality of electrical signals are in one-to-one correspondence. The processing circuit 1704 and the processing circuit 1601 can be the same processor.

[0094] Figure 18 This is the structural schematic diagram of the optical communication system provided by the embodiment of the present application. As Figure 18 shown, the optical communication system 1800 includes an optical communication device 1801 and another optical communication device 1802. The optical communication device 1801 and the another optical communication device 1802 are connected by an optical fiber or a waveguide. The optical fiber can be a single-mode optical fiber, a multi-mode optical fiber, an imaging optical fiber, a multi-core optical fiber, a light guiding optical fiber, or a plastic optical fiber, etc. The waveguide can be a flexible optical waveguide or a dielectric optical waveguide, etc. The optical communication device 1801 is used to transmit one or more optical signals to the another optical communication device 1802. For the description of the optical communication device 1801, reference can be made to the foregoing description of Figures 13 - 17Description of the optical communication device in any figure. When the optical communication device 1801 is Figure 13 , Figure 14 or Figure 15 the optical communication device, the optical communication device 1801 is used to transmit an optical signal to another optical communication device 1802. When the optical communication device 1801 is Figure 16 or Figure 17 the optical communication device, the optical communication device 1801 is used to transmit multiple optical signals to another optical communication device 1802. For the description of another optical communication device 1802, reference can be made to the description of the optical communication device 1801.

[0095] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should be covered by the protection scope of the present application.

Claims

1. A light-emitting diode LED, characterized in that, It includes a P-type semiconductor layer, an active layer, and an N-type semiconductor layer, where: The active layer is located between the P-type semiconductor layer and the N-type semiconductor layer. The active layer includes M barrier layers and M - 1 well layers, which are alternately distributed. M is an integer greater than 1. Each of the M barrier layers is a P-type doped layer. The sum of the doping concentrations of N first barrier layers among the M barrier layers close to the N-type semiconductor layer is greater than the sum of the doping concentrations of N second barrier layers among the M barrier layers close to the P-type semiconductor layer. When M is an even number, N = M / 2; when M is an odd number, N = M / 2 - 1 / 2.

2. The LED according to claim 1, wherein, The P-type edge barrier layer is the barrier layer closest to the P-type semiconductor layer among the M barrier layers. The N-type edge barrier layer is the barrier layer closest to the N-type semiconductor layer among the M barrier layers. The target barrier layer is a non-edge barrier layer among the M barrier layers. The doping concentration of the barrier layers from the N-type edge barrier layer to the target barrier layer gradually increases, and the doping concentration of the barrier layers from the target barrier layer to the P-type edge barrier layer gradually decreases.

3. The LED according to claim 2, wherein, M is equal to 6. In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the doping concentrations of the M barrier layers are C1, C2, C3, C4, C5, and C6 respectively, where C1 < C2 > C3 > C4 > C5 > C6.

4. The LED according to claim 1, wherein In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the doping concentrations of the M barrier layers gradually decrease.

5. The LED according to claim 4, wherein M is equal to 6. In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the doping concentrations of the M barrier layers are C1, C2, C3, C4, C5, and C6 respectively, where C1 > C2 > C3 > C4 > C5 > C6.

6. The LED according to claim 1, wherein The doping concentrations of X barrier layers among the M barrier layers close to the N-type semiconductor layer are the same. The doping concentrations of Y barrier layers among the M barrier layers close to the P-type semiconductor layer are the same. The doping concentration of the barrier layers in the X barrier layers is different from the doping concentration of the barrier layers in the Y barrier layers. M is equal to the sum of X and Y.

7. The LED according to claim 6, wherein, M is equal to 6. In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the doping concentrations of the M barrier layers are C1, C2, C3, C4, C5, and C6 respectively, where C1 = C2 = C3 > C4 = C5 = C6.

8. The LED according to claim 1, characterized in that, The doping concentrations of X barrier layers among the M barrier layers close to the N-type semiconductor layer are the same. The doping concentrations of Y barrier layers among the M barrier layers close to the P-type semiconductor layer are the same. Among the M barrier layers, excluding the X barrier layers and the Y barrier layers, the doping concentrations of Z barrier layers are the same. The doping concentration of the barrier layers in the X barrier layers is greater than the doping concentration of the barrier layers in the Z barrier layers. The doping concentration of the barrier layers in the Z barrier layers is greater than the doping concentration of the barrier layers in the Y barrier layers. M is equal to the sum of X, Y, and Z.

9. The LED according to claim 8, characterized in that, M is equal to 6. In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the doping concentrations of the M barrier layers are C1, C2, C3, C4, C5, and C6 respectively, where C1 = C2 > C3 = C4 > C5 = C6.

10. The LED according to any one of claims 1 to 9, characterized in that, The doping concentration range of the highest doping concentration among the M barrier layers is between 1×10 18 and 1×10 21 per cubic centimeter, and the doping concentration range of the lowest doping concentration among the M barrier layers is between 1×10 16 and 1×10 18 per cubic centimeter.

11. The LED according to any one of claims 1 to 10, characterized in that, The sum of the thicknesses of the K first barrier layers and the K first well layers among the M barrier layers and the M - 1 well layers, which are close to the N-type semiconductor, is greater than the sum of the thicknesses of the K second barrier layers and the K second well layers, which are close to the P-type semiconductor. When M is an even number, K = M / 2 - 1; when M is an odd number, K = M / 2 - 1 / 2.

12. The LED according to claim 11, wherein The thicknesses of the M - 1 well layers are the same, and the thicknesses of the M barrier layers are different.

13. The LED according to claim 12, wherein The thicknesses of the K first barrier layers are the same, the thicknesses of the K second barrier layers are the same, and the thickness of the first barrier layer is greater than that of the second barrier layer.

14. The LED according to claim 12, wherein The M barrier layers include X first barrier layers and Y second barrier layers, M is equal to the sum of X and Y, the thicknesses of the X first barrier layers are the same, the thicknesses of the Y second barrier layers are the same, and the thickness of the first barrier layer is greater than that of the second barrier layer.

15. The LED according to claim 11, characterized in that, The thicknesses of the M barrier layers are the same, and the thicknesses of the M - 1 well layers are different.

16. The LED according to claim 15, characterized in that, The thicknesses of the K first well layers are the same, the thicknesses of the K second well layers are the same, and the thickness of the first well layer is greater than that of the second well layer.

17. The LED according to claim 15, wherein The M - 1 well layers include X - 1 first well layers and Y second well layers, M is equal to the sum of X and Y, the thicknesses of the X - 1 first well layers are the same, the thicknesses of the Y second well layers are the same, and the thickness of the first well layer is greater than that of the second well layer.

18. The LED according to claim 11, wherein The thicknesses of the M barrier layers are different, and the thicknesses of the M - 1 well layers are different.

19. The LED according to claim 18, wherein The M barrier layers include X first barrier layers and Y second barrier layers, M is equal to the sum of X and Y, the thicknesses of the X first barrier layers are the same, the thicknesses of the Y second barrier layers are the same, and the thickness of the first barrier layer is greater than that of the second barrier layer.

20. The LED according to claim 18, characterized in that, The M - 1 well layers include X - 1 first well layers and Y second well layers, M is equal to the sum of X and Y, the thicknesses of the X - 1 first well layers are the same, the thicknesses of the Y second well layers are the same, and the thickness of the first well layer is greater than that of the second well layer.

21. A light-emitting diode LED array, characterized in that, Comprising another LED and the LED according to any one of the preceding claims 1 to 20, and the another LED and the LED share the same substrate.

22. An optical communication device, characterized in that, Comprising the light-emitting diode LED according to any one of the preceding claims 1 to 20 or the LED array according to the preceding claim 21, the optical communication device further comprises a processing circuit, wherein: The processing circuit is configured to transmit an electrical signal to the LED or the LED array; The LED or the LED array is configured to generate an optical signal according to the electrical signal.

23. The optical communication device according to claim 22, characterized in that, The optical communication device further comprises an optical coupling structure, wherein: The optical coupling structure is configured to reduce the emission angle of the LEDs in the LED or the LED array.

24. The optical communication device according to claim 22 or 23, characterized in that, The optical communication device further comprises a detector PD or a PD array, wherein: The PD or the PD array is configured to receive another optical signal and convert the another optical signal into another electrical signal; The processing circuit is configured to receive the another electrical signal.

25. The optical communication device according to claim 24, characterized in that, The optical communication device further comprises another optical coupling structure, wherein: The another optical coupling structure is configured to condense the another optical signal. The PD or the PD array is configured to convert the concentrated another optical signal into the another electrical signal.

26. An optical communication system, characterized in that, Comprising another optical communication device and the optical communication device according to any one of the preceding claims 22 to 25, wherein: The optical communication device and the another optical communication device are connected by an optical fiber or an optical waveguide, and the optical communication device is configured to transmit an optical signal to the another optical communication device.

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