Light emitting diode and method for manufacturing the same

Abstract

The present invention provides a light-emitting diode and a manufacturing method thereof, wherein the light-emitting diode comprises a substrate, a first semiconductor layer, a quantum well layer and a second semiconductor layer from bottom to top, wherein the doping type of the first semiconductor layer is n-type, the second semiconductor layer comprises at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottom semiconductor layer and the quantum well layer and between adjacent semiconductor layers, and the doping type of the bottom and top semiconductor layers is p-type, and the doping type of the remaining semiconductor layers is p-type or unintentionally doped, and two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer, the quantum well layer and the semiconductor layer. The technical solution of the present invention reduces the difference in the concentration of electrons and holes in the quantum well layer, thereby significantly improving the photoelectric conversion efficiency of the light-emitting diode.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a light emitting diode and a manufacturing method thereof. Background Art

[0002] Semiconductor light emitting diodes have the advantages of a wide adjustable wavelength range, high luminous efficiency, energy saving and environmental protection, long life, small size and strong designability. They have gradually replaced incandescent lamps and fluorescent lamps and become the light source for ordinary household lighting. They are also widely used in new scenarios, such as Mini-LED, indoor high-resolution display screens, outdoor display screens, mobile phone backlights, TV backlights, laptop backlights, household lamps, street lights, car lights and flashlights.

[0003] However, in traditional light-emitting diodes, nitride semiconductor layers are generally grown on sapphire substrates using heteroepitaxial growth. Nitride semiconductor layers include n-type semiconductor layers, quantum well layers, and p-type semiconductor layers from bottom to top. The hole ionization efficiency of traditional nitride semiconductor layers is much lower than the electron ionization efficiency, resulting in a hole concentration that is 1 to 2 orders of magnitude lower than the electron concentration. Excess electrons cannot participate in radiative recombination and overflow from the quantum well layer to the p-type semiconductor layer to produce non-radiative recombination. At the same time, low hole ionization efficiency leads to low hole concentration in the p-type semiconductor layer and difficulty in effectively injecting holes into the quantum well layer, resulting in low efficiency of hole injection into the quantum well layer. Therefore, the difference between the electron and hole concentrations in the quantum well layer is large, the probability of electron and hole wave function overlap is low, and the recombination efficiency of electrons and holes in the quantum well layer is low, resulting in low luminescence efficiency of the quantum well layer.

[0004] Therefore, a light emitting diode and a method for manufacturing the same are provided to improve the light emitting efficiency of the light emitting diode. Summary of the invention

[0005] The object of the present invention is to provide a light emitting diode and a method for manufacturing the same, so that the difference in the concentration of electrons and holes in the quantum well layer is reduced, thereby significantly improving the photoelectric conversion efficiency of the light emitting diode.

[0006] To achieve the above-mentioned purpose, the present invention provides a light-emitting diode, comprising a substrate, a first semiconductor layer, a quantum well layer and a second semiconductor layer from bottom to top, the doping type of the first semiconductor layer is n-type, the second semiconductor layer comprises at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottommost semiconductor layer and the quantum well layer, an unintentionally doped AlN layer is formed between adjacent semiconductor layers, and the doping type of the bottommost and topmost semiconductor layers is p-type, the doping type of the remaining semiconductor layers is p-type or is unintentionally doped, a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the quantum well layer, and a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the semiconductor layer.

[0007] Optionally, the second semiconductor layer has the functions of multiple two-dimensional hole gas tunneling acceleration and multiple electron tunneling deceleration.

[0008] Optionally, the second semiconductor layer includes a first region close to the quantum well layer, a second region away from the quantum well layer, and an intermediate region between the first region and the second region, the first region, the intermediate region and the second region each contain at least one layer of the semiconductor layer, and the first region, the intermediate region and the second region each contain at least one layer of the unintentionally doped AlN layer.

[0009] Optionally, an Al composition in the semiconductor layer in the second region is less than an Al composition in the semiconductor layer in the first region and less than an Al composition in the semiconductor layer in the middle region.

[0010] Optionally, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer and the quantum well layer in the first region and between adjacent semiconductor layers is a,

[0011] Optionally, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the middle region and the topmost semiconductor layer in the first region and between adjacent semiconductor layers in the middle region is b,

[0012] Optionally, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the second region and the topmost semiconductor layer in the middle region and between adjacent semiconductor layers in the second region is c,

[0013] Optionally, the sum of the thicknesses of the semiconductor layers in the first region is d,

[0014] Optionally, the sum of the thicknesses of the semiconductor layers in the middle region is e,

[0015] Optionally, the sum of the thicknesses of the semiconductor layers in the second region is f,

[0016] Optionally, the second semiconductor layer includes a first p-type semiconductor layer, an unintentionally doped semiconductor layer, and a second p-type semiconductor layer stacked from bottom to top, the first p-type semiconductor layer is located in the first region, the unintentionally doped semiconductor layer is located in the middle region, and the second p-type semiconductor layer is located in the second region.

[0017] Optionally, the material of the first semiconductor layer, the quantum well layer and the semiconductor layer includes at least one of GaN, AlGaN, InGaN, AlInGaN, InN and AlInN.

[0018] The present invention also provides a method for manufacturing a light emitting diode, comprising:

[0019] providing a substrate;

[0020] A first semiconductor layer, a quantum well layer, and a second semiconductor layer are sequentially formed on the substrate, wherein the doping type of the first semiconductor layer is n-type, the second semiconductor layer includes at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottom semiconductor layer and the quantum well layer, an unintentionally doped AlN layer is formed between adjacent semiconductor layers, and the doping types of the bottom and top semiconductor layers are p-type, and the doping types of the remaining semiconductor layers are p-type or unintentionally doped, a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the quantum well layer, and a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the semiconductor layer.

[0021] Optionally, the second semiconductor layer has the functions of multiple two-dimensional hole gas tunneling acceleration and multiple electron tunneling deceleration.

[0022] Optionally, the second semiconductor layer includes a first region close to the quantum well layer, a second region away from the quantum well layer, and an intermediate region between the first region and the second region, the first region, the intermediate region and the second region each contain at least one layer of the semiconductor layer, and the first region, the intermediate region and the second region each contain at least one layer of the unintentionally doped AlN layer.

[0023] Optionally, an Al composition in the semiconductor layer in the second region is less than an Al composition in the semiconductor layer in the first region and less than an Al composition in the semiconductor layer in the middle region.

[0024] Optionally, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer and the quantum well layer in the first region and between adjacent semiconductor layers is a,

[0025] Optionally, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the middle region and the topmost semiconductor layer in the first region and between adjacent semiconductor layers in the middle region is b,

[0026] Optionally, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the second region and the topmost semiconductor layer in the middle region and between adjacent semiconductor layers in the second region is c,

[0027] Optionally, the sum of the thicknesses of the semiconductor layers in the first region is d,

[0028] Optionally, the sum of the thicknesses of the semiconductor layers in the middle region is e,

[0029] Optionally, the sum of the thicknesses of the semiconductor layers in the second region is f,

[0030] Optionally, the second semiconductor layer includes a first p-type semiconductor layer, an unintentionally doped semiconductor layer, and a second p-type semiconductor layer stacked from bottom to top, the first p-type semiconductor layer is located in the first region, the unintentionally doped semiconductor layer is located in the middle region, and the second p-type semiconductor layer is located in the second region.

[0031] Optionally, the material of the first semiconductor layer, the quantum well layer and the semiconductor layer includes at least one of GaN, AlGaN, InGaN, AlInGaN, InN and AlInN.

[0032] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0033] The light-emitting diode and the manufacturing method thereof of the present invention, since the second semiconductor layer includes at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottom semiconductor layer and the quantum well layer, an unintentionally doped AlN layer is formed between adjacent semiconductor layers, and the doping type of the bottom and top semiconductor layers is p-type, and the doping type of the remaining semiconductor layers is p-type or unintentionally doped, a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the quantum well layer, and a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the semiconductor layer, so that the effects of multiple electron tunneling deceleration and multiple two-dimensional hole gas tunneling acceleration can be achieved simultaneously, thereby reducing the difference in electron and hole concentrations in the quantum well layer, increasing the probability of electron and hole wave function overlap, and increasing the radiation recombination efficiency of electrons and holes in the quantum well layer, thereby increasing the luminescence efficiency of the quantum well layer, and thus significantly improving the photoelectric conversion efficiency of the light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic structural diagram of a light emitting diode according to an embodiment of the present invention;

[0035] Figure 2 is a transmission electron microscope image of a light emitting diode according to an embodiment of the present invention;

[0036] Figure 3 The figure is a flow chart of a method for manufacturing a light emitting diode according to an embodiment of the present invention.

[0037] Among them, Figure 1 to Figure 3 The reference numerals are described as follows:

[0038] 11-substrate; 12-first semiconductor layer; 13-quantum well layer; 14-second semiconductor layer; 141-first unintentionally doped AlN layer; 142-first p-type semiconductor layer; 143-second unintentionally doped AlN layer; 144-unintentionally doped semiconductor layer; 145-third unintentionally doped AlN layer; 146-second p-type semiconductor layer. DETAILED DESCRIPTION

[0039] In order to make the purpose, advantages and features of the present invention more clear, the light emitting diode and the manufacturing method thereof proposed by the present invention are further described in detail below. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0040] An embodiment of the present invention provides a light-emitting diode, comprising a substrate, a first semiconductor layer, a quantum well layer and a second semiconductor layer from bottom to top, wherein the doping type of the first semiconductor layer is n-type, the second semiconductor layer comprises at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottommost semiconductor layer and the quantum well layer, an unintentionally doped AlN layer is formed between adjacent semiconductor layers, and the doping type of the bottommost and topmost semiconductor layers is p-type, the doping type of the remaining semiconductor layers is p-type or is unintentionally doped, a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the quantum well layer, and a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the semiconductor layer.

[0041] See below Figure 1 and Figure 2 The light emitting diode provided in this embodiment is described in more detail. Figure 1 and Figure 2 It is also a longitudinal cross-section of a light-emitting diode.

[0042] The light-emitting diode includes a substrate 11, a first semiconductor layer 12, a quantum well layer 13 and a second semiconductor layer 14 from bottom to top, the doping type of the first semiconductor layer 12 is n-type, the second semiconductor layer 14 includes at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottom semiconductor layer and the quantum well layer 13, and an unintentionally doped AlN layer is formed between adjacent semiconductor layers, then, the second semiconductor layer 14 includes at least three layers of the unintentionally doped AlN layer.

[0043] Among them, the doping type of the bottom and top semiconductor layers is p-type, and the doping type of the remaining semiconductor layers is p-type or unintentionally doped, and two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the quantum well layer 13, and two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the semiconductor layer.

[0044] Among them, since the second semiconductor layer 14 includes at least three layers of the unintentionally doped AlN layer, each layer of the unintentionally doped AlN layer has two junctions with its adjacent structure, and therefore, at least 6 interfaces of two-dimensional hole gas are formed in the light-emitting diode. It should be noted that the two-dimensional hole gas at the junction of the bottom unintentionally doped AlN layer and the quantum well layer 13 is only located in the unintentionally doped AlN layer, and the two-dimensional hole gas at the junction of other unintentionally doped AlN layers and the semiconductor layer can be located in both the unintentionally doped AlN layer and the semiconductor layer.

[0045] Furthermore, when the doping type of the remaining semiconductor layers is p-type, at least three layers of the unintentionally doped AlN layers and at least three layers of semiconductor layers with a doping type of p-type are formed on the quantum well layer 13, so that a stacking structure of at least three layers of undoped u-doped p is formed on the quantum well layer 13, at this time, the undoped u is the unintentionally doped AlN layer, and the doped p is the semiconductor layer with a doping type of p-type; when the remaining semiconductor layers are unintentionally doped, at least three layers of the unintentionally doped AlN layers, at least one layer of unintentionally doped semiconductor layers and at least two layers of semiconductor layers with a doping type of p-type are formed on the quantum well layer 13, so that a stacking structure of at least two layers of undoped u-doped p is formed on the quantum well layer 13, at this time, the undoped u is a combination of the unintentionally doped AlN layer and the unintentionally doped semiconductor layer or a single layer of the unintentionally doped AlN layer, and the doped p is the semiconductor layer with a doping type of p-type. Therefore, at least two layers of non-doped u-doped p-doped stacking structures are formed on the quantum well layer 13 .

[0046] exist Figure 1-2 In the embodiment shown, the second semiconductor layer 14 includes three stacked semiconductor layers, the doping type of the bottom and top semiconductor layers is p-type, and the semiconductor layer in the middle layer is unintentionally doped, that is, a first p-type semiconductor layer 142, an unintentionally doped semiconductor layer 144, and a second p-type semiconductor layer 146 are stacked from bottom to top, a first unintentionally doped AlN layer 141 is formed between the bottom first p-type semiconductor layer 142 and the quantum well layer 13, a second unintentionally doped AlN layer 143 is formed between the first p-type semiconductor layer 142 and the unintentionally doped semiconductor layer 144, and the unintentionally doped semiconductor layer 146 is formed between the first p-type semiconductor layer 142 and the unintentionally doped semiconductor layer 144. A third unintentionally doped AlN layer 145 is formed between the first unintentionally doped AlN layer 141 and the quantum well layer 13 and the first p-type semiconductor layer 142, two-dimensional hole gases A1 and A2 are formed at the interface between the first unintentionally doped AlN layer 141, the quantum well layer 13 and the first p-type semiconductor layer 142, two-dimensional hole gases A3 and A4 are formed at the interface between the second unintentionally doped AlN layer 143, the first p-type semiconductor layer 142 and the unintentionally doped semiconductor layer 144, and two-dimensional hole gases A5 and A6 are formed at the interface between the third unintentionally doped AlN layer 145, the unintentionally doped semiconductor layer 144 and the second p-type semiconductor layer 146. In other embodiments, the doping type of the semiconductor layer in the middle layer may also be p-type; compared with the doping type of the semiconductor layer in the middle layer being p-type, when the semiconductor layer in the middle layer is unintentionally doped, the brightness and light efficiency of the light emitting diode are higher.

[0047] Among them, Figure 1-2In the illustrated embodiment, two layers of undoped u-doped p stacking structures are formed on the quantum well layer 13, i.e., an undoped u-doped p-undoped u-doped p structure from bottom to top, the undoped u of the bottom layer is the first unintentionally doped AlN layer 141, the doped p of the bottom layer is the first p-type semiconductor layer 142, the undoped u of the top layer is a combination of the second unintentionally doped AlN layer 143, the unintentionally doped semiconductor layer 144 and the third unintentionally doped AlN layer 145, and the doped p of the top layer is the second p-type semiconductor layer 146.

[0048] The materials of the first semiconductor layer 12, the quantum well layer 13 and the semiconductor layer may include at least one of nitride semiconductor materials such as GaN, AlGaN, InGaN, AlInGaN, InN and AlInN, and the materials of the first semiconductor layer 12, the quantum well layer 13 and the semiconductor layer do not include AlN.

[0049] Among them, the principle of forming the two-dimensional hole gas is: due to the large difference in Al composition between the material AlN of the unintentionally doped AlN layer and the materials of the quantum well layer 13 and the semiconductor layer (the Al composition of the material AlN of the unintentionally doped AlN layer is 100%, and the Al composition of the materials of the quantum well layer 13 and the semiconductor layer is much less than 100%), resulting in the formation of two-dimensional hole gas at the junction of the unintentionally doped AlN layer, the quantum well layer 13 and the semiconductor layer due to energy band changes.

[0050] In existing light-emitting diodes, since the electron concentration in the quantum well layer is very high and much higher than the hole concentration, the electrons cannot completely radiate and recombine in the quantum well layer, resulting in excess electrons overflowing from the quantum well layer to the p-type semiconductor layer to produce non-radiative recombination; and the hole concentration in the p-type semiconductor is also low, making it difficult to effectively inject holes longitudinally into the quantum well layer. Therefore, the difference between the electron and hole concentrations in the quantum well layer is large, the probability of electron and hole wave function overlap is low, and the radiative recombination efficiency of electrons and holes in the quantum well layer is low, which in turn leads to low luminescence efficiency of the quantum well layer, and thus low photoelectric conversion efficiency of the light-emitting diode.

[0051] In an embodiment of the present invention, the second semiconductor layer 14 includes at least three stacked semiconductor layers, which is equivalent to dividing the second semiconductor layer 14 into at least three semiconductor layers, and inserting the unintentionally doped AlN layer between the quantum well layer 13 and the bottom semiconductor layer and between adjacent semiconductor layers. Since AlN has a high potential barrier, the unintentionally doped AlN layer acts as a barrier layer, and a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer, the quantum well layer 13 and the semiconductor layer. The barrier layer and the two-dimensional hole gas can both block the electrons overflowing from the quantum well layer 13, so that the electrons overflowing from the quantum well layer 13 are decelerated, thereby reducing the number of electrons overflowing from the quantum well layer 13 into the semiconductor layer with a doping type of p-type, thereby reducing the probability of non-radiative recombination of electrons overflowing into the semiconductor layer with a doping type of p-type and holes, thereby improving the hole injection efficiency and expansion capability, and improving the radiative recombination efficiency of electrons and holes in the quantum well layer 13.

[0052] Furthermore, by forming at least two layers of non-doped u-doped p stacking structures on the quantum well layer 13, and forming a two-dimensional hole gas at the interface between the non-intentionally doped AlN layer, the quantum well layer 13 and the semiconductor layer, the two-dimensional hole gas can provide more holes, so that the longitudinal tunneling acceleration injection capability and lateral expansion capability of the holes can be improved, thereby increasing the hole concentration in the semiconductor layer with a doping type of p-type, so that the holes can be effectively injected longitudinally into the quantum well layer 13. Furthermore, at least 6 interfaces of two-dimensional hole gas are formed in the light-emitting diode, so that sufficient longitudinal hole injection capability and lateral expansion capability can be provided.

[0053] Therefore, it can be seen from the above content that the second semiconductor layer 14 of the present invention can simultaneously achieve the effects of multiple electron tunneling deceleration and multiple two-dimensional hole gas tunneling acceleration, so that the difference in electron and hole concentrations in the quantum well layer 13 is reduced, the probability of electron and hole wave function overlap is increased, and the radiation recombination efficiency of electrons and holes in the quantum well layer 13 is improved, thereby improving the luminescence efficiency of the quantum well layer 13, thereby significantly improving the photoelectric conversion efficiency of the light-emitting diode (for example, greater than 70%).

[0054] Furthermore, the second semiconductor layer 14 may include a first region close to the quantum well layer 13, a second region away from the quantum well layer 13, and an intermediate region located between the first region and the second region, the first region, the intermediate region and the second region all contain at least one layer of the semiconductor layer, and the first region, the intermediate region and the second region all contain at least one layer of the unintentionally doped AlN layer.

[0055] Preferably, the Al composition of the semiconductor layer in the second region is less than the Al composition of the semiconductor layer in the first region and less than the Al composition of the semiconductor layer in the middle region. When the first region, the middle region and the second region each contain at least two layers of the semiconductor layer, the Al composition of each layer of the semiconductor layer in the first region may be equal or unequal, the Al composition of each layer of the semiconductor layer in the middle region may be equal or unequal, and the Al composition of each layer of the semiconductor layer in the second region may be equal or unequal.

[0056] Among them, due to the gradient difference between the Al components in the semiconductor layers in the first region, the middle region and the second region, the Al components in the semiconductor layers in the first region, the middle region and the second region and the unintentionally doped AlN layers in contact with each layer of the semiconductor layers are different, so that each layer of the unintentionally doped AlN layer has a different deceleration effect on the electrons overflowing from the quantum well layer 13. Under the above-mentioned gradient difference in the Al components in the semiconductor layers in the first region, the middle region and the second region, each layer of the unintentionally doped AlN layer has the best deceleration effect on the electrons overflowing from the quantum well layer 13.

[0057] Preferably, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer and the quantum well layer 13 and between adjacent semiconductor layers in the first region is a. and / or, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the middle region and the topmost semiconductor layer in the first region and between adjacent semiconductor layers in the middle region is b, and / or, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the second region and the topmost semiconductor layer in the middle region and between adjacent semiconductor layers in the second region is c, Among them, when the first region, the middle region and the second region contain at least two layers of the unintentionally doped AlN layer, the thickness of each layer of the unintentionally doped AlN layer in the first region may be equal or unequal, the thickness of each layer of the unintentionally doped AlN layer in the middle region may be equal or unequal, and the thickness of each layer of the unintentionally doped AlN layer in the second region may be equal or unequal.

[0058] Among them, for the sum of the thickness of all unintentionally doped AlN layers in the first region, the sum of the thickness of all unintentionally doped AlN layers in the middle region, and the sum of the thickness of all unintentionally doped AlN layers in the second region, if it is less than the minimum value of the above range, it will result in the inability to form two-dimensional hole gas, and the electron deceleration and hole lateral expansion functions cannot be achieved. If it is greater than the maximum value of the above range, the electron tunneling function cannot be achieved, and the longitudinal injection of holes will be blocked, resulting in an increase in resistance value and a high voltage.

[0059] Preferably, the sum of the thicknesses of the semiconductor layers in the first region is d, If the sum of the thicknesses d of the semiconductor layers in the first region is less than This results in a failure to generate sufficient hole concentration, which in turn results in a decrease in photoelectric conversion efficiency; if the sum of the thicknesses d of the semiconductor layers in the first region is greater than This will result in an increase in the ratio of light absorption and non-radiative recombination, leading to a decrease in photoelectric conversion efficiency.

[0060] Preferably, the sum of the thicknesses of the semiconductor layers in the middle region is e, If the sum of the thicknesses e of the semiconductor layers in the middle region is less than The functions of electron deceleration and hole lateral expansion cannot be achieved; if the sum of the thicknesses e of the semiconductor layers in the middle region is greater than The hole tunneling function cannot be realized, and there is a problem of high resistance, which leads to abnormally high voltage and reduced photoelectric conversion efficiency.

[0061] Preferably, the sum of the thicknesses of the semiconductor layers in the second region is f, In the process of growing and forming the second semiconductor layer 14, defects in each layer structure will extend upward, and finally a V-shaped pit defect will be formed on the top of the second semiconductor layer 14. By controlling the sum of the thicknesses of the semiconductor layers in the second region (especially the thickness of the semiconductor layer at the top), the V-shaped pit defect can be filled. Therefore, if the sum of the thicknesses of the semiconductor layers in the second region is less than This will result in the inability to fill the V-shaped pit defect, and thus the inability to form a flat epitaxial layer surface. At the same time, it will also cause the contact voltage between the second semiconductor layer 14 and the electrode connected thereto to be abnormally high. If the sum of the thicknesses f of the semiconductor layers in the second region is greater than This will cause defects related to the doped Mg (such as Mg complexes or impurities) to be generated in the semiconductor layer with p-type doping in the second region, thereby increasing the probability of light absorption and non-radiative recombination, thereby reducing the photoelectric conversion efficiency.

[0062] Wherein, when the first region, the middle region and the second region all contain at least two layers of the semiconductor layers, the thickness of each layer of the semiconductor layers in the first region may be equal or unequal, the thickness of each layer of the semiconductor layers in the middle region may be equal or unequal, and the thickness of each layer of the semiconductor layers in the second region may be equal or unequal.

[0063] exist Figure 1 and Figure 2 In the illustrated embodiment, the first unintentionally doped AlN layer 141 and the first p-type semiconductor layer 142 are located in the first region, the second unintentionally doped AlN layer 143 and the unintentionally doped semiconductor layer 144 are located in the middle region, and the third unintentionally doped AlN layer 145 and the second p-type semiconductor layer 146 are located in the second region.

[0064] Preferably, the Al component in the second p-type semiconductor layer 146 is less than the Al component in the first p-type semiconductor layer 142 and less than the Al component in the unintentionally doped semiconductor layer 144; preferably, the thickness of the first unintentionally doped AlN layer 141 is And / or, the thickness of the second unintentionally doped AlN layer 143 is And / or, the thickness of the third unintentionally doped AlN layer 145 is Preferably, the thickness of the first p-type semiconductor layer 142 is And / or, the thickness of the unintentionally doped semiconductor layer 144 is And / or, the thickness of the second p-type semiconductor layer 146 is Among them, Figure 2 The thickness of the first unintentionally doped AlN layer 141 is shown in FIG. The thickness of the first p-type semiconductor layer 142 is The thickness of the second unintentionally doped AlN layer 143 is The thickness of the unintentionally doped semiconductor layer 144 is The thickness of the third unintentionally doped AlN layer 145 is The thickness of the second p-type semiconductor layer 146 is

[0065] In summary, the light-emitting diode provided by the present invention comprises a substrate, a first semiconductor layer, a quantum well layer and a second semiconductor layer from bottom to top, the doping type of the first semiconductor layer is n-type, the second semiconductor layer comprises at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottom semiconductor layer and the quantum well layer, an unintentionally doped AlN layer is formed between adjacent semiconductor layers, and the doping type of the bottom and top semiconductor layers is p-type, the doping type of the remaining semiconductor layers is p-type or unintentionally doped, a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the quantum well layer, and a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the semiconductor layer. The light-emitting diode provided by the present invention reduces the difference in the concentration of electrons and holes in the quantum well layer, thereby significantly improving the photoelectric conversion efficiency of the light-emitting diode.

[0066] An embodiment of the present invention provides a method for manufacturing a light emitting diode. Figure 3 , Figure 3 1 is a flow chart of a method for manufacturing a light emitting diode according to an embodiment of the present invention, wherein the method for manufacturing a light emitting diode comprises:

[0067] Step S1, providing a substrate;

[0068] Step S2, sequentially forming a first semiconductor layer, a quantum well layer and a second semiconductor layer on the substrate, wherein the doping type of the first semiconductor layer is n-type, the second semiconductor layer includes at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottom semiconductor layer and the quantum well layer, an unintentionally doped AlN layer is formed between adjacent semiconductor layers, and the doping type of the bottom and top semiconductor layers is p-type, and the doping type of the remaining semiconductor layers is p-type or unintentionally doped, a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the quantum well layer, and a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the semiconductor layer.

[0069] See below Figure 1 and Figure 2 The method for manufacturing the light emitting diode provided in this embodiment is described in more detail.

[0070] According to step S1, a substrate 11 is provided.

[0071] According to step S2, a first semiconductor layer 12, a quantum well layer 13 and a second semiconductor layer 14 are sequentially formed on the substrate 11, wherein the doping type of the first semiconductor layer 12 is n-type, and the second semiconductor layer 14 includes at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottom semiconductor layer and the quantum well layer 13, and unintentionally doped AlN layers are formed between adjacent semiconductor layers, then, the second semiconductor layer 14 includes at least three layers of the unintentionally doped AlN layers.

[0072] Among them, the doping type of the bottom and top semiconductor layers is p-type, and the doping type of the remaining semiconductor layers is p-type or unintentionally doped, and two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the quantum well layer 13, and two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the semiconductor layer.

[0073] The first semiconductor layer 12, the quantum well layer 13 and the second semiconductor layer 14 are sequentially formed on the substrate 11 by epitaxial growth. When growing the first semiconductor layer 12, silane can be used as a dopant; if the doping type of the semiconductor layer is p-type, magnesium cyclopentadienyl can be used as a dopant when growing the semiconductor layer.

[0074] Among them, since the second semiconductor layer 14 includes at least three layers of the unintentionally doped AlN layer, each layer of the unintentionally doped AlN layer has two junctions with its adjacent structure, and therefore, at least 6 interfaces of two-dimensional hole gas are formed in the light-emitting diode. It should be noted that the two-dimensional hole gas at the junction of the bottom unintentionally doped AlN layer and the quantum well layer 13 is only located in the unintentionally doped AlN layer, and the two-dimensional hole gas at the junction of other unintentionally doped AlN layers and the semiconductor layer can be located in both the unintentionally doped AlN layer and the semiconductor layer.

[0075] Furthermore, when the doping type of the remaining semiconductor layers is p-type, at least three layers of the unintentionally doped AlN layers and at least three layers of semiconductor layers with a doping type of p-type are formed on the quantum well layer 13, so that a stacking structure of at least three layers of undoped u-doped p is formed on the quantum well layer 13, at this time, the undoped u is the unintentionally doped AlN layer, and the doped p is the semiconductor layer with a doping type of p-type; when the remaining semiconductor layers are unintentionally doped, at least three layers of the unintentionally doped AlN layers, at least one layer of unintentionally doped semiconductor layers and at least two layers of semiconductor layers with a doping type of p-type are formed on the quantum well layer 13, so that a stacking structure of at least two layers of undoped u-doped p is formed on the quantum well layer 13, at this time, the undoped u is a combination of the unintentionally doped AlN layer and the unintentionally doped semiconductor layer or a single layer of the unintentionally doped AlN layer, and the doped p is the semiconductor layer with a doping type of p-type. Therefore, at least two layers of non-doped u-doped p-doped stacking structures are formed on the quantum well layer 13 .

[0076] exist Figure 1-2 In the embodiment shown, the second semiconductor layer 14 includes three stacked semiconductor layers, the doping type of the bottom and top semiconductor layers is p-type, and the semiconductor layer in the middle layer is unintentionally doped, that is, a first p-type semiconductor layer 142, an unintentionally doped semiconductor layer 144, and a second p-type semiconductor layer 146 are stacked from bottom to top, a first unintentionally doped AlN layer 141 is formed between the bottom first p-type semiconductor layer 142 and the quantum well layer 13, a second unintentionally doped AlN layer 143 is formed between the first p-type semiconductor layer 142 and the unintentionally doped semiconductor layer 144, and the unintentionally doped semiconductor layer 146 is formed between the first p-type semiconductor layer 142 and the unintentionally doped semiconductor layer 144. A third unintentionally doped AlN layer 145 is formed between the first unintentionally doped AlN layer 141 and the quantum well layer 13 and the first p-type semiconductor layer 142, two-dimensional hole gases A1 and A2 are formed at the interface between the first unintentionally doped AlN layer 141, the quantum well layer 13 and the first p-type semiconductor layer 142, two-dimensional hole gases A3 and A4 are formed at the interface between the second unintentionally doped AlN layer 143, the first p-type semiconductor layer 142 and the unintentionally doped semiconductor layer 144, and two-dimensional hole gases A5 and A6 are formed at the interface between the third unintentionally doped AlN layer 145, the unintentionally doped semiconductor layer 144 and the second p-type semiconductor layer 146. In other embodiments, the doping type of the semiconductor layer in the middle layer may also be p-type; compared with the doping type of the semiconductor layer in the middle layer being p-type, when the semiconductor layer in the middle layer is unintentionally doped, the brightness and light efficiency of the light emitting diode are higher.

[0077] Among them, Figure 1-2In the illustrated embodiment, two layers of undoped u-doped p stacking structures are formed on the quantum well layer 13, i.e., an undoped u-doped p-undoped u-doped p structure from bottom to top, the undoped u of the bottom layer is the first unintentionally doped AlN layer 141, the doped p of the bottom layer is the first p-type semiconductor layer 142, the undoped u of the top layer is a combination of the second unintentionally doped AlN layer 143, the unintentionally doped semiconductor layer 144 and the third unintentionally doped AlN layer 145, and the doped p of the top layer is the second p-type semiconductor layer 146.

[0078] The materials of the first semiconductor layer 12, the quantum well layer 13 and the semiconductor layer may include at least one of nitride semiconductor materials such as GaN, AlGaN, InGaN, AlInGaN, InN and AlInN, and the materials of the first semiconductor layer 12, the quantum well layer 13 and the semiconductor layer do not include AlN.

[0079] Among them, the principle of forming the two-dimensional hole gas is: due to the large difference in Al composition between the material AlN of the unintentionally doped AlN layer and the materials of the quantum well layer 13 and the semiconductor layer (the Al composition of the material AlN of the unintentionally doped AlN layer is 100%, and the Al composition of the materials of the quantum well layer 13 and the semiconductor layer is much less than 100%), resulting in the formation of two-dimensional hole gas at the junction of the unintentionally doped AlN layer, the quantum well layer 13 and the semiconductor layer due to energy band changes.

[0080] In existing light-emitting diodes, since the electron concentration in the quantum well layer is very high and much higher than the hole concentration, the electrons cannot completely radiate and recombine in the quantum well layer, resulting in excess electrons overflowing from the quantum well layer to the p-type semiconductor layer to produce non-radiative recombination; and the hole concentration in the p-type semiconductor is also low, making it difficult to effectively inject holes longitudinally into the quantum well layer. Therefore, the difference between the electron and hole concentrations in the quantum well layer is large, the probability of electron and hole wave function overlap is low, and the radiative recombination efficiency of electrons and holes in the quantum well layer is low, which in turn leads to low luminescence efficiency of the quantum well layer, and thus low photoelectric conversion efficiency of the light-emitting diode.

[0081] In an embodiment of the present invention, the second semiconductor layer 14 includes at least three stacked semiconductor layers, which is equivalent to dividing the second semiconductor layer 14 into at least three semiconductor layers, and inserting the unintentionally doped AlN layer between the quantum well layer 13 and the bottom semiconductor layer and between adjacent semiconductor layers. Since AlN has a high potential barrier, the unintentionally doped AlN layer acts as a barrier layer, and a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer, the quantum well layer 13 and the semiconductor layer. The barrier layer and the two-dimensional hole gas can both block the electrons overflowing from the quantum well layer 13, so that the electrons overflowing from the quantum well layer 13 are decelerated, thereby reducing the number of electrons overflowing from the quantum well layer 13 into the semiconductor layer with a doping type of p-type, thereby reducing the probability of non-radiative recombination of electrons overflowing into the semiconductor layer with a doping type of p-type and holes, thereby improving the hole injection efficiency and expansion capability, and improving the radiative recombination efficiency of electrons and holes in the quantum well layer 13.

[0082] Furthermore, by forming at least two layers of non-doped u-doped p stacking structures on the quantum well layer 13, and forming a two-dimensional hole gas at the interface between the non-intentionally doped AlN layer, the quantum well layer 13 and the semiconductor layer, the two-dimensional hole gas can provide more holes, so that the longitudinal tunneling acceleration injection capability and lateral expansion capability of the holes can be improved, thereby increasing the hole concentration in the semiconductor layer with a doping type of p-type, so that the holes can be effectively injected longitudinally into the quantum well layer 13. Furthermore, at least 6 interfaces of two-dimensional hole gas are formed in the light-emitting diode, so that sufficient longitudinal hole injection capability and lateral expansion capability can be provided.

[0083] Therefore, it can be seen from the above content that the second semiconductor layer 14 of the present invention can simultaneously achieve the effects of multiple electron tunneling deceleration and multiple two-dimensional hole gas tunneling acceleration, so that the difference in electron and hole concentrations in the quantum well layer 13 is reduced, the probability of electron and hole wave function overlap is increased, and the radiation recombination efficiency of electrons and holes in the quantum well layer 13 is improved, thereby improving the luminescence efficiency of the quantum well layer 13, thereby significantly improving the photoelectric conversion efficiency of the light-emitting diode (for example, greater than 70%).

[0084] Furthermore, the second semiconductor layer 14 may include a first region close to the quantum well layer 13, a second region away from the quantum well layer 13, and an intermediate region located between the first region and the second region, the first region, the intermediate region and the second region all contain at least one layer of the semiconductor layer, and the first region, the intermediate region and the second region all contain at least one layer of the unintentionally doped AlN layer.

[0085] Preferably, the Al composition of the semiconductor layer in the second region is less than the Al composition of the semiconductor layer in the first region and less than the Al composition of the semiconductor layer in the middle region. When the first region, the middle region and the second region each contain at least two layers of the semiconductor layer, the Al composition of each layer of the semiconductor layer in the first region may be equal or unequal, the Al composition of each layer of the semiconductor layer in the middle region may be equal or unequal, and the Al composition of each layer of the semiconductor layer in the second region may be equal or unequal.

[0086] Among them, due to the gradient difference between the Al components in the semiconductor layers in the first region, the middle region and the second region, the Al components in the semiconductor layers in the first region, the middle region and the second region and the unintentionally doped AlN layers in contact with each layer of the semiconductor layers are different, so that each layer of the unintentionally doped AlN layer has a different deceleration effect on the electrons overflowing from the quantum well layer 13. Under the above-mentioned gradient difference in the Al components in the semiconductor layers in the first region, the middle region and the second region, each layer of the unintentionally doped AlN layer has the best deceleration effect on the electrons overflowing from the quantum well layer 13.

[0087] Preferably, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer and the quantum well layer 13 and between adjacent semiconductor layers in the first region is a. and / or, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the middle region and the topmost semiconductor layer in the first region and between adjacent semiconductor layers in the middle region is b, and / or, the sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the second region and the topmost semiconductor layer in the middle region and between adjacent semiconductor layers in the second region is c, Among them, when the first region, the middle region and the second region contain at least two layers of the unintentionally doped AlN layer, the thickness of each layer of the unintentionally doped AlN layer in the first region may be equal or unequal, the thickness of each layer of the unintentionally doped AlN layer in the middle region may be equal or unequal, and the thickness of each layer of the unintentionally doped AlN layer in the second region may be equal or unequal.

[0088] Among them, for the sum of the thickness of all unintentionally doped AlN layers in the first region, the sum of the thickness of all unintentionally doped AlN layers in the middle region, and the sum of the thickness of all unintentionally doped AlN layers in the second region, if it is less than the minimum value of the above range, it will result in the inability to form two-dimensional hole gas, and the electron deceleration and hole lateral expansion functions cannot be achieved. If it is greater than the maximum value of the above range, the electron tunneling function cannot be achieved, and the longitudinal injection of holes will be blocked, resulting in an increase in resistance value and a high voltage.

[0089] Preferably, the sum of the thicknesses of the semiconductor layers in the first region is d, If the sum of the thicknesses d of the semiconductor layers in the first region is less than This results in a failure to generate sufficient hole concentration, which in turn results in a decrease in photoelectric conversion efficiency; if the sum of the thicknesses d of the semiconductor layers in the first region is greater than This will result in an increase in the ratio of light absorption and non-radiative recombination, leading to a decrease in photoelectric conversion efficiency.

[0090] Preferably, the sum of the thicknesses of the semiconductor layers in the middle region is e, If the sum of the thicknesses e of the semiconductor layers in the middle region is less than The functions of electron deceleration and hole lateral expansion cannot be achieved; if the sum of the thicknesses e of the semiconductor layers in the middle region is greater than The hole tunneling function cannot be realized, and there is a problem of high resistance, which leads to abnormally high voltage and reduced photoelectric conversion efficiency.

[0091] Preferably, the sum of the thicknesses of the semiconductor layers in the second region is f, In the process of growing and forming the second semiconductor layer 14, defects in each layer structure will extend upward, and finally a V-shaped pit defect will be formed on the top of the second semiconductor layer 14. By controlling the sum of the thicknesses of the semiconductor layers in the second region (especially the thickness of the semiconductor layer at the top), the V-shaped pit defect can be filled. Therefore, if the sum of the thicknesses of the semiconductor layers in the second region is less than This will result in the inability to fill the V-shaped pit defect, and thus the inability to form a flat epitaxial layer surface. At the same time, it will also cause the contact voltage between the second semiconductor layer 14 and the electrode connected thereto to be abnormally high. If the sum of the thicknesses f of the semiconductor layers in the second region is greater than This will cause defects related to the doped Mg (such as Mg complexes or impurities) to be generated in the semiconductor layer with p-type doping in the second region, thereby increasing the probability of light absorption and non-radiative recombination, thereby reducing the photoelectric conversion efficiency.

[0092] Wherein, when the first region, the middle region and the second region all contain at least two layers of the semiconductor layers, the thickness of each layer of the semiconductor layers in the first region may be equal or unequal, the thickness of each layer of the semiconductor layers in the middle region may be equal or unequal, and the thickness of each layer of the semiconductor layers in the second region may be equal or unequal.

[0093] exist Figure 1 and Figure 2 In the illustrated embodiment, the first unintentionally doped AlN layer 141 and the first p-type semiconductor layer 142 are located in the first region, the second unintentionally doped AlN layer 143 and the unintentionally doped semiconductor layer 144 are located in the middle region, and the third unintentionally doped AlN layer 145 and the second p-type semiconductor layer 146 are located in the second region.

[0094] Preferably, the Al component in the second p-type semiconductor layer 146 is less than the Al component in the first p-type semiconductor layer 142 and less than the Al component in the unintentionally doped semiconductor layer 144; preferably, the thickness of the first unintentionally doped AlN layer 141 is And / or, the thickness of the second unintentionally doped AlN layer 143 is And / or, the thickness of the third unintentionally doped AlN layer 145 is Preferably, the thickness of the first p-type semiconductor layer 142 is And / or, the thickness of the unintentionally doped semiconductor layer 144 is And / or, the thickness of the second p-type semiconductor layer 146 is Among them, Figure 2 The thickness of the first unintentionally doped AlN layer 141 is shown in FIG. The thickness of the first p-type semiconductor layer 142 is The thickness of the second unintentionally doped AlN layer 143 is The thickness of the unintentionally doped semiconductor layer 144 is The thickness of the third unintentionally doped AlN layer 145 is The thickness of the second p-type semiconductor layer 146 is

[0095] In summary, the method for manufacturing a light-emitting diode provided by the present invention comprises: providing a substrate; sequentially forming a first semiconductor layer, a quantum well layer and a second semiconductor layer on the substrate, wherein the doping type of the first semiconductor layer is n-type, the second semiconductor layer comprises at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottom semiconductor layer and the quantum well layer, an unintentionally doped AlN layer is formed between adjacent semiconductor layers, and the doping type of the bottom and top semiconductor layers is p-type, and the doping type of the remaining semiconductor layers is p-type or unintentionally doped, a two-dimensional hole gas is formed at the interface between the unintentionally doped AlN layer and the quantum well layer, and a two-dimensional hole gas is formed at the interface between the unintentionally doped AlN layer and the semiconductor layer. The method for manufacturing a light-emitting diode provided by the present invention reduces the difference in the concentration of electrons and holes in the quantum well layer, thereby significantly improving the photoelectric conversion efficiency of the light-emitting diode.

[0096] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A light emitting diode, characterized in that: It includes a substrate, a first semiconductor layer, a quantum well layer and a second semiconductor layer from bottom to top, the doping type of the first semiconductor layer is n-type, the second semiconductor layer includes at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottom semiconductor layer and the quantum well layer, an unintentionally doped AlN layer is formed between adjacent semiconductor layers, and the doping type of the bottom and top semiconductor layers is p-type, the doping type of the remaining semiconductor layers is p-type or is unintentionally doped, a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the quantum well layer, and a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the semiconductor layer.

2. The light emitting diode according to claim 1, characterized in that The second semiconductor layer has the functions of multiple two-dimensional hole gas tunneling acceleration and multiple electron tunneling deceleration.

3. The light emitting diode according to claim 1, characterized in that The second semiconductor layer includes a first region close to the quantum well layer, a second region away from the quantum well layer, and an intermediate region located between the first region and the second region, the first region, the intermediate region and the second region each contain at least one layer of the semiconductor layer, and the first region, the intermediate region and the second region each contain at least one layer of the unintentionally doped AlN layer.

4. The light emitting diode according to claim 3, characterized in that An Al composition in the semiconductor layer in the second region<an Al composition in the semiconductor layer in the first region<an Al composition in the semiconductor layer in the intermediate region.

5. The light emitting diode according to claim 3, characterized in that: The sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer and the quantum well layer and between adjacent semiconductor layers in the first region is a, 6. The light emitting diode according to claim 3, characterized in that The sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the middle region and the topmost semiconductor layer in the first region and between adjacent semiconductor layers in the middle region is b, 7. The light emitting diode according to claim 3, characterized in that: The sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the second region and the topmost semiconductor layer in the middle region and between adjacent semiconductor layers in the second region is c, 8. The light emitting diode according to claim 3, characterized in that: The sum of the thicknesses of the semiconductor layers in the first region is d, 9. The light emitting diode according to claim 3, characterized in that: The sum of the thicknesses of the semiconductor layers in the middle region is e, 10. The light emitting diode according to claim 3, characterized in that: The sum of the thicknesses of the semiconductor layers in the second region is f, 11. The light emitting diode according to any one of claims 3 to 10, characterized in that The second semiconductor layer includes a first p-type semiconductor layer, an unintentionally doped semiconductor layer, and a second p-type semiconductor layer stacked from bottom to top, the first p-type semiconductor layer is located in the first region, the unintentionally doped semiconductor layer is located in the middle region, and the second p-type semiconductor layer is located in the second region.

12. The light emitting diode according to claim 1, characterized in that The material of the first semiconductor layer, the quantum well layer and the semiconductor layer includes at least one of GaN, AlGaN, InGaN, AlInGaN, InN and AlInN.

13. A method for manufacturing a light emitting diode, characterized in that: include: providing a substrate; A first semiconductor layer, a quantum well layer, and a second semiconductor layer are sequentially formed on the substrate, wherein the doping type of the first semiconductor layer is n-type, the second semiconductor layer includes at least three stacked semiconductor layers, an unintentionally doped AlN layer is formed between the bottom semiconductor layer and the quantum well layer, an unintentionally doped AlN layer is formed between adjacent semiconductor layers, and the doping types of the bottom and top semiconductor layers are p-type, and the doping types of the remaining semiconductor layers are p-type or unintentionally doped, a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the quantum well layer, and a two-dimensional hole gas is formed at the junction of the unintentionally doped AlN layer and the semiconductor layer.

14. The method for manufacturing a light emitting diode according to claim 13, wherein: The second semiconductor layer has the functions of multiple two-dimensional hole gas tunneling acceleration and multiple electron tunneling deceleration.

15. The method for manufacturing a light emitting diode according to claim 13, wherein: The second semiconductor layer includes a first region close to the quantum well layer, a second region away from the quantum well layer, and an intermediate region located between the first region and the second region, the first region, the intermediate region and the second region each contain at least one layer of the semiconductor layer, and the first region, the intermediate region and the second region each contain at least one layer of the unintentionally doped AlN layer.

16. The method for manufacturing a light emitting diode according to claim 15, wherein: An Al composition in the semiconductor layer in the second region<an Al composition in the semiconductor layer in the first region<an Al composition in the semiconductor layer in the intermediate region.

17. The method for manufacturing a light emitting diode according to claim 15, wherein: The sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer and the quantum well layer and between adjacent semiconductor layers in the first region is a, 18. The method for manufacturing a light emitting diode according to claim 15, wherein: The sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the middle region and the topmost semiconductor layer in the first region and between adjacent semiconductor layers in the middle region is b, 19. The method for manufacturing a light emitting diode according to claim 15, wherein: The sum of the thicknesses of the unintentionally doped AlN layers between the bottommost semiconductor layer in the second region and the topmost semiconductor layer in the middle region and between adjacent semiconductor layers in the second region is c, 20. The method for manufacturing a light emitting diode according to claim 15, wherein: The sum of the thicknesses of the semiconductor layers in the first region is d, 21. The method for manufacturing a light emitting diode according to claim 15, wherein: The sum of the thicknesses of the semiconductor layers in the middle region is e, 22. The method for manufacturing a light emitting diode according to claim 15, wherein: The sum of the thicknesses of the semiconductor layers in the second region is f, 23. The method for manufacturing a light emitting diode according to any one of claims 15 to 22, characterized in that: The second semiconductor layer includes a first p-type semiconductor layer, an unintentionally doped semiconductor layer, and a second p-type semiconductor layer stacked from bottom to top, the first p-type semiconductor layer is located in the first region, the unintentionally doped semiconductor layer is located in the middle region, and the second p-type semiconductor layer is located in the second region.

24. The method for manufacturing a light emitting diode according to claim 13, wherein: The material of the first semiconductor layer, the quantum well layer and the semiconductor layer includes at least one of GaN, AlGaN, InGaN, AlInGaN, InN and AlInN.

Images