Light emitting diode and light emitting device

Abstract

The invention discloses a light-emitting diode and a light-emitting device, the light-emitting diode comprises an epitaxial stack structure, the epitaxial stack structure sequentially comprises an N-type semiconductor layer, an active layer and a P-type semiconductor layer from bottom to top, the active layer is located between the N-type semiconductor layer and the P-type semiconductor layer, the P-type semiconductor layer comprises a P-type cladding layer, and the P-type cladding layer is located between the N-type semiconductor layer and the P-type semiconductor layer. The P-type coating layer comprises a first doping layer and a second doping layer which are adjacent to each other, the first doping layer is close to the active layer, the doping concentration of the first doping layer is increased from the first doping concentration on one side close to the active layer to the second doping concentration on one side far away from the active layer, and the doping concentration of the second doping layer is greater than or equal to the second doping concentration. Therefore, diffusion of the P-type semiconductor layer from a high-concentration region to a low-concentration region can be buffered, the problem that P-type impurities enter the active layer to cause overlarge deviation of electron and hole recombination positions is avoided, and the luminous efficiency and reliability of the light-emitting diode are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a light emitting diode and a light emitting device. Background Art

[0002] Light Emitting Diode (LED) is a semiconductor device that can directly convert electrical energy into light energy, and is a solid-state cold light source. The inherent physical properties of LED enable it to operate at low voltage / current, and it has the characteristics of high luminous efficiency, small size, long life, and energy saving, and is considered to be the best light source. In recent years, LED has been widely used in daily life, such as lighting, signal lights, backlight sources, car lights, and large-screen displays. At the same time, these applications have put forward higher requirements on the brightness and reliability of LED.

[0003] Red LED chips are generally made of AlGaInP quaternary materials. The epitaxial growth technology of red LEDs is mainly to grow AlGaInP materials on GaAs growth substrates. Since the lattice matching between AlGaInP and GaAs is good, fewer dislocations are generated during the epitaxial growth process, and the quantum efficiency inside the AlGaInP material exceeds 95%. However, the internal quantum efficiency of existing red light epitaxial structures is still affected by the diffusion of doped atoms in the semiconductor layer, resulting in a decrease in light extraction efficiency and reduced reliability. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a light emitting diode and a light emitting device to further improve the internal quantum efficiency and reliability of the light emitting diode.

[0005] In order to achieve the above-mentioned purpose and other related purposes, the present invention provides a light-emitting diode, which includes an epitaxial stack structure, which includes, from bottom to top, an N-type semiconductor layer, an active layer and a P-type semiconductor layer, the active layer is located between the N-type semiconductor layer and the P-type semiconductor layer, the P-type semiconductor layer includes a P-type cladding layer, the P-type cladding layer includes adjacent first doping layers and second doping layers, the first doping layer is close to the active layer, the doping concentration of the first doping layer increases from a first doping concentration on a side close to the active layer to a second doping concentration on a side away from the active layer, and the doping concentration of the second doping layer is greater than or equal to the second doping concentration.

[0006] According to one aspect of the present invention, there is also provided a light emitting device, which includes a circuit substrate and at least one light emitting element located on the circuit substrate, wherein the light emitting element includes the above-mentioned light emitting diode.

[0007] Compared with the prior art, the light emitting diode and the light emitting device of the present invention have at least the following beneficial effects:

[0008] The light emitting diode of the present invention comprises an epitaxial stacking structure, the epitaxial stacking structure comprises an N-type semiconductor layer, an active layer and a P-type semiconductor layer from bottom to top, the P-type semiconductor layer comprises a P-type cladding layer, the P-type cladding layer comprises an adjacent first doping layer and a second doping layer, the first doping layer is arranged close to the active layer, the doping concentration of the first doping layer increases from the first doping concentration on the side close to the active layer to the side away from the active layer to the second doping concentration, and the doping concentration of the second doping layer is greater than or equal to the second doping concentration. Thus, the arrangement of the first doping layer arranged close to the active layer in the P-type cladding layer of the present invention with the doping concentration increasing in the direction away from the active layer can buffer the diffusion of the P-type semiconductor layer from the high concentration region (the second doping layer) to the low concentration region (the active layer), prevent the diffusion of the P-type impurities into the active layer and affect the recombination position of the electrons and holes in the active layer, so that the recombination position deviates too much and affects the luminous efficiency and reliability of the light emitting diode, thereby improving the luminous efficiency and reliability of the light emitting diode.

[0009] The light emitting device of the present invention includes the above-mentioned light emitting diode and also has the above-mentioned technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic diagram of the structure of an epitaxial stack structure of a light emitting diode according to an embodiment of the present invention;

[0011] Figure 2 A schematic diagram of the variation of doping concentration in a P-type space layer and a P-type cladding layer in an example of an embodiment of the present invention;

[0012] Figure 3 A schematic diagram of the variation of doping concentration in a P-type space layer and a P-type cladding layer in another example of an embodiment of the present invention;

[0013] Figure 4 A schematic diagram of the variation of doping concentration in a P-type space layer and a P-type cladding layer in another example of an embodiment of the present invention;

[0014] Figure 5 A schematic diagram of the structure of a light emitting diode in an example of an embodiment of the present invention;

[0015] Figure 6 A schematic diagram of the structure of a light emitting diode in another example of an embodiment of the present invention;

[0016] Figure 7 FIG. 4 is a schematic diagram of the structure of a light emitting device in an embodiment of the present invention.

[0017] List of reference numerals:

[0018] 100 Growth substrate

[0019] 200 buffer layer

[0020] 300 Etching stop layer

[0021] 400 N-type ohmic contact layer

[0022] 500 N-type current blocking layer

[0023] 510 N-type current expansion layer

[0024] 001 epitaxial stacking structure

[0025] 600 epitaxial layer

[0026] 601 N-type semiconductor layer

[0027] 6011 N-type coating

[0028] 6012 N-type space layer

[0029] 602 Active layer

[0030] 603 P-type semiconductor layer

[0031] 6031 P-type space layer

[0032] 6032 P-type cladding

[0033] 6032-1 first doping layer

[0034] 6032-2 Second doping layer

[0035] AThe first doping concentration

[0036] B The second doping concentration

[0037] 700 Transition Layer

[0038] 800 P-type current spreading layer

[0039] 900 P-type ohmic contact layer

[0040] 1000 bonding layers

[0041] 1010 Bonding Substrate

[0042] 1021 P-type electrode

[0043] 1022 N-type electrode

[0044] 10 Lighting Device

[0045] 11 Circuit board

[0046] 12 Light emitting elements

[0047] 13 circuit layers DETAILED DESCRIPTION

[0048] The following specific embodiments illustrate the embodiments of the present invention, and those familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0049] It should be noted that the diagrams provided in the embodiments of the present invention are only used to illustrate the basic concept of the present invention in a schematic manner. Although the diagrams only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, the form, quantity and proportion of each component can be changed at will during actual implementation, and the layout of the components may also be more complex. The structures, proportions, sizes, etc. illustrated in the drawings of the specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions that can be implemented in this application, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by the present invention.

[0050] In the prior art, the higher the doping of the P-type semiconductor layer, the more effectively the conduction band gap difference between the P-type semiconductor layer and the active layer can be improved, thereby reducing the current of the leakage electrons and improving the luminescence efficiency of the epitaxial structure. The inventors have experimentally found that due to the different physical and chemical properties of P-type doping atoms such as Mg and Zn and the replaced group III source atoms, the chemical bonds of the doping atoms in the crystal material are unstable, and there is a phenomenon of diffusion from the high concentration area to the low concentration area under the action of the electric field or thermal field. At the same time, the diffusion distance of the doping atoms increases with the increase of the doping concentration. If the doping concentration is too high, the diffusion of the doping atoms will cause the electron and hole recombination positions to deviate too much, and even the doping atoms will diffuse into the active area to form non-radiative recombination centers, reducing the luminescence efficiency and reliability of the device.

[0051] In order to solve the problems existing in the background technology and the above-mentioned technical problems, this embodiment provides a light emitting diode, including:

[0052] An epitaxial stack structure, the epitaxial stack structure includes an N-type semiconductor layer, an active layer and a P-type semiconductor layer from bottom to top, the active layer is located between the N-type semiconductor layer and the P-type semiconductor layer, the P-type semiconductor layer includes a P-type cladding layer, the P-type cladding layer includes adjacent first doping layers and second doping layers, the first doping layer is close to the active layer, the doping concentration of the first doping layer increases from the first doping concentration on the side close to the active layer to the side away from the active layer to the second doping concentration, and the doping concentration of the second doping layer is greater than or equal to the second doping concentration. Therefore, the arrangement of the first doping layer arranged close to the active layer in the P-type cladding layer of the P-type semiconductor layer of this embodiment with an increasing doping concentration in a direction away from the active layer can buffer the diffusion of the P-type semiconductor layer from a high concentration region (second doping layer) to a low concentration region (active layer), avoid the phenomenon that the electron and hole recombination position deviates too much due to the entry of P-type impurities into the active layer, and improve the luminous efficiency and reliability of the light-emitting diode.

[0053] Optionally, the P-type semiconductor layer further includes:

[0054] The P-type space layer is disposed between the active layer and the P-type cladding layer, and the doping concentration of the P-type space layer increases from the first unintentional doping concentration to the first doping concentration in a direction away from the active layer. In this embodiment, the arrangement of the P-type space layer can further buffer the doping atoms diffused from the P-type semiconductor layer and prevent the P-type doping atoms from entering the active layer.

[0055] Optionally, the first unintentional doping concentration is in the range of 1E16 atoms / cm 3 ~1E17 atoms / cm 3 .

[0056] Optionally, the value of the first doping concentration is between 1E17 atoms / cm 3 ~5E17 atoms / cm 3 .

[0057] Optionally, the value of the second doping concentration is greater than or equal to 5E17 atoms / cm 3 .

[0058] Optionally, the doping concentration of the second doping layer is not greater than 2E18 atoms / cm 3 .

[0059] Optionally, the thickness of the first doping layer is t1, the thickness of the second doping layer is t2, and the thickness of the first doping layer is greater than the thickness of the second doping layer. Setting the thickness t1 of the first doping layer to be greater than the thickness t2 of the second doping layer can prevent too many diffused atoms of the second doping layer from crossing the first doping layer into the active layer, which has a certain blocking effect on the diffused atoms.

[0060] Optionally, the relationship between the thickness of the first doping layer and the thickness of the second doping layer is: 1<t1 / t2<2. The thickness of the first doping layer and the second doping layer is more conducive to the effective recombination of electrons and holes in the active layer, while avoiding the diffusion of doping atoms.

[0061] Optionally, the atomic radius of the doped atoms in the P-type semiconductor layer is smaller than the atomic radius of the group III element doped and substituted in the P-type semiconductor layer. Since the doped atomic radius in the P-type semiconductor layer is smaller than the substituted atomic radius, the chemical bonds in the P-type semiconductor layer are unstable and are prone to diffusion from high-concentration areas to low-concentration areas. When they diffuse into the active area, they affect the recombination position of holes and electrons, reducing the luminous efficiency of the light-emitting diode.

[0062] Optionally, the doping atoms of the first doping layer and the second doping layer are Mg and / or Zn. When the doping atoms in the P-type semiconductor layer are Mg, their mixing into the active layer will increase the non-radiative recombination probability of the active layer and reduce the luminous efficiency.

[0063] Optionally, the thickness of the P-type cladding layer is between 0.3 μm and 4 μm.

[0064] Optionally, the thickness of the P-type space layer is

[0065] Optionally, the material of the active layer is AlGaInP material.

[0066] Optionally, the material of the first doping layer and the second doping layer is AlInP material.

[0067] Optionally, the material of the P-type space layer is Al x Ga (1-x) InP, where 0.5≤x≤0.8.

[0068] Optionally, the epitaxial stack structure further includes:

[0069] The transition layer is arranged above the P-type semiconductor layer. The transition layer is used for lattice transition between layers to improve the growth quality of the epitaxial structure layer.

[0070] The P-type current expansion layer is arranged above the transition layer, and is used for current expansion to improve the light-emitting efficiency of the light-emitting diode.

[0071] The P-type ohmic contact layer is arranged above the P-type current spreading layer, and the P-type ohmic contact layer is used for forming a good ohmic contact between the electrode and the epitaxial structure.

[0072] Optionally, the N-type semiconductor layer includes:

[0073] The N-type cladding layer has N-type doping and provides electrons for the active layer.

[0074] Optionally, the N-type semiconductor layer further includes:

[0075] The N-type space layer is disposed between the N-type cladding layer and the active layer. In this embodiment, the N-type space layer is used to block impurities from entering the active layer, ensuring that electrons effectively recombine with holes in the active layer to emit light.

[0076] Optionally, the epitaxial stack structure further includes:

[0077] The N-type ohmic contact layer is arranged on a side of the N-type cladding layer away from the active layer, and the N-type ohmic contact layer is used to form a good ohmic contact between the N-electrode and the epitaxial structure.

[0078] The N-type current blocking layer is arranged above the N-type ohmic contact layer and below the N-type cladding layer. The N-type current blocking layer is arranged to prevent electron overflow.

[0079] According to one aspect of the present invention, this embodiment further provides a light-emitting device, the light-emitting device comprising a circuit substrate and at least one light-emitting element located on the circuit substrate, the light-emitting element comprising the above-mentioned light-emitting diode. The P-type cladding layer of the P-type semiconductor layer of the light-emitting diode comprises a first doping layer that increases the doping concentration in a direction away from the active layer, the first doping layer can buffer the diffusion of the P-type semiconductor layer from a high-concentration region to a low-concentration region, prevent P-type impurities from entering the active layer, resulting in excessive deviation of the recombination position of electrons and holes, and affect the light-emitting efficiency and reliability of the light-emitting diode.

[0080] The present invention is described in detail below with reference to specific embodiments.

[0081] Example 1

[0082] This embodiment provides an epitaxial stack structure of a light emitting diode. Figure 1 , the epitaxial stack structure 001 is arranged on the growth substrate 100 .

[0083] The material of the growth substrate 100 includes but is not limited to one of GaAs, InP and GaP. This embodiment is described by taking the growth substrate 100 as GaAs as an example. The thickness of the growth substrate 100 can be set according to requirements. Optionally, the thickness of the growth substrate 100 is between 200 μm and 500 μm, for example, 350 μm.

[0084] The epitaxial stack structure 001 includes an epitaxial layer 600, and the epitaxial layer 600 includes an N-type semiconductor layer 601, an active layer 602, and a P-type semiconductor layer 603. It should be noted that the epitaxial stack structure 001 may include only the epitaxial layer 600 having a light-emitting function, or may include a doped layer for other functions other than the epitaxial layer 600, for example, an ohmic contact layer or a current spreading layer.

[0085] The N-type semiconductor layer 601 is disposed above the growth substrate 100 and is doped with N-type impurities to provide electrons for composite light emission. The N-type impurities may be Si, Ge, Sn, Se or Te. In this embodiment, the N-type impurities are Si.

[0086] The active layer 602 is disposed above the N-type semiconductor layer 601 and can provide an area for providing light radiation for the recombination of electrons and holes. Different materials can be selected according to different luminescent wavelengths. The active layer 602 can be a periodic structure of a single quantum well or multiple quantum wells. The active layer 602 includes a well layer and a barrier layer, wherein the barrier layer has a larger band gap than the well layer. By adjusting the composition ratio of the semiconductor material in the active layer 602, it is expected to radiate light of different wavelengths. In this embodiment, the active layer 602 is a multiple quantum well layer, and the repetition period of the well layer and the barrier layer is between 10 and 60. The material of the active layer 602 is Al x Ga 1-x InP, 0.5≤x≤0.8, the thickness of each well layer or each barrier layer is between

[0087] The P-type semiconductor layer 603 is arranged above the active layer 602. The P-type semiconductor layer 603 is doped with P-type impurities to provide holes for compound luminescence. Among them, the P-type impurities can be Mg, Zn, Ca, Sr or Ba. In the prior art, the higher the doping of the P-type semiconductor layer 603, the more effectively the conduction band gap difference between the P-type semiconductor layer 603 and the active layer 602 can be improved, thereby reducing the current of the leakage electrons and improving the luminescence efficiency of the epitaxial structure. However, since the physical and chemical properties of P-type doping atoms such as Mg and Zn are different from those of the replaced group III source atoms, and their atomic radius is smaller than the atomic radius of the replaced group III elements, the chemical bonds of the doping atoms in the crystal material are unstable. If a P-type semiconductor layer is formed by a doping technology that is easy to diffuse, there is a phenomenon of diffusion from a high concentration area to a low concentration area in the layer under the action of an electric field or a thermal field. At the same time, the distance and length of the diffusion of doping atoms increase with the increase of doping concentration. If the doping concentration is too high, the diffusion of doping atoms will cause the electron and hole recombination positions to deviate too much, and even the doping atoms will diffuse into the active region to form non-radiative recombination centers, reducing the luminous efficiency and reliability of the device. Therefore, in order to avoid the excessive deviation of the recombination positions of electrons and holes caused by the diffusion of diffused atoms, the doping concentration of the P-type semiconductor layer 603 is set in this embodiment to avoid excessive diffusion of doping atoms in the P-type semiconductor layer 603 into the active layer 602, which affects the recombination positions of electrons and holes.

[0088] Specifically, refer to Figure 1 In this embodiment, the P-type semiconductor layer 603 includes a P-type cladding layer 6032, and the P-type cladding layer 6032 includes a first doping layer 6032-1 and a second doping layer 6032-2, wherein the first doping layer 6032-1 is disposed close to the active layer 602. Figure 2 , 3 Or 4, the doping concentration of the first doping layer 6032-1 increases from the first doping concentration A on the side close to the active layer 602 to the second doping concentration B on the side away from the active layer 602, and the doping concentration of the second doping layer 6032-2 is greater than or equal to the second doping concentration B. Therefore, in this embodiment, the doping concentration of the first doping layer 6032-1 of the P-type cladding layer 6032 increases from the direction away from the active layer 602, which can buffer the diffusion of the P-type semiconductor layer 603 from the high concentration area to the low concentration area, avoid the problem of excessive deviation of the recombination position of electrons and holes caused by the entry of P-type impurities into the active layer 602, and improve the luminous efficiency and reliability of the light-emitting diode. It should be noted that with the increase of the layer thickness, the change trend from the first doping concentration A to the second doping concentration B in this embodiment is not fixed. For example, it can be as follows Figure 2 The irregular increasing trend in Figure 3 The linear trend in Figure 4Of course, there may also be a trend of increasing slowly first and then increasing sharply. Of course, there may also be a trend of increasing sharply first and then increasing sharply, and then increasing slightly and then increasing sharply. Moreover, since its doping concentration is affected by the diffusion of some doping elements, there may be a situation where the doping concentration in some areas decreases or the doping concentration in some areas remains the same, but it will eventually increase to the second doping concentration. The present invention does not limit the trend of the first doping concentration A increasing to the second doping concentration B. Furthermore, the second doping concentration B in the second doping layer 6032-2 is not the same at each thickness position in the second doping layer 6032-2, and its data may be equal to or slightly greater than the second doping concentration B, such as Figure 4 In addition, Figure 2-4 The 0-A part is a P-type space layer, and the 0 point generally has a certain doping concentration. The doping concentration is consistent with the doping concentration of the active layer, and both come from the background concentration of the gas reaction chamber.

[0089] In this embodiment, the value of the first doping concentration A is less than the value of the second doping concentration B. Optionally, the value of the first doping concentration A is between 1E17 and 5E17 atoms / cm 3 The values ​​in this interval are all the first doping concentration A, and the values ​​of the second doping concentration B are greater than or equal to 5E17 atoms / cm 3 The values ​​in this interval are all the second doping concentration B. Preferably, the second doping concentration B is between 5E17 atoms / cm 3 ~2E18 atoms / cm 3 between, for example, 1E18 atoms / cm 3 In one example, the first doping concentration A is 1E17 atoms / cm 3 The second doping concentration B is 5E17 atoms / cm 3 Optionally, the doping concentration of the second doping layer 6032-2 is greater than or equal to the second doping concentration B, but the doping concentration of the second doping layer 6032-2 is not greater than 2E18 atoms / cm 3 The thickness of the first doping layer 6032-1 is t1, and the thickness of the second doping layer 6032-2 is t2. The thickness t1 of the first doping layer 6032-1 is greater than the thickness t2 of the second doping layer 6032-2, which can prevent too many diffused atoms of the second doping layer 6032-2 from crossing the first doping layer 6032-1 and entering the active layer 602, and has a certain blocking effect on the diffused atoms.

[0090] In this embodiment, the relationship between the thickness of the first doping layer 6032-1 and the thickness of the second doping layer 6032-2 is: 1<t1 / t2<2. The thickness of the first doping layer 6032-1 and the second doping layer 6032-2 is more conducive to the effective recombination of electrons and holes in the active layer 602, while avoiding the diffusion of doped atoms. Optionally, the thickness of the P-type cladding layer 6032 is 0.3μm to 4μm. For example, the thickness of the P-type cladding layer 6032 is 1μm, the thickness of the first doping layer 6032-1 is 0.6μm, and the thickness of the second doping layer 6032-2 is 0.4μm. In this embodiment, the material of the P-type cladding layer 6032 is AlInP, and the atomic radius of the doping atoms of the P-type semiconductor layer 603 is smaller than the atomic radius of the III group element replaced by the doping, for example, it can be Mg, Zn, Ca, Sr or Ba. Since the radius of the above doping atoms is smaller than the radius of the replaced atoms, it is easier to diffuse. In this embodiment, the doping atoms of the P-type semiconductor layer 603 are Mg and / or Zn. When the doping atoms in the P-type semiconductor layer are Mg, their mixing into the active layer will increase the probability of non-radiative recombination of the active layer and reduce the luminous efficiency. The first doping layer 6032-1 with a gradient doping concentration provided in the P-type cladding layer 6032 of the P-type semiconductor layer 603 in this embodiment can have a certain blocking effect on the doping atoms Mg, thereby improving the luminous efficiency.

[0091] In an optional embodiment, the P-type semiconductor layer 603 further includes a P-type space layer 6031, which is disposed between the P-type cladding layer 6032 and the active layer 602, and is an unintentionally doped space region, or a passively doped region, and is used to limit the diffusion of holes, and ensure that holes can effectively recombine with electrons in the active layer 602 to emit light. Due to the diffusion of doped impurities in the P cladding layer and the background concentration of doped elements in the gas reaction chamber during the epitaxial production process, the P-type space layer 6031 in the final product has a certain doping concentration generated by unintentional doping, which is a first unintentional doping concentration, and its concentration is lower than the first doping concentration A. In this embodiment, the doping concentration of the P-type space layer 6031 increases to the first doping concentration along the direction away from the active layer 602. For example, the doping concentration of the P-type space layer 6031 increases from the first unintentional doping concentration less than the first doping concentration to the first doping concentration along the direction away from the active layer 602. In this embodiment, the first unintentional doping concentration ranges from 1E16 atoms / cm 3 ~1E17 atoms / cm 3 The P-type space layer 6031 in this embodiment can further buffer the doping atoms diffused from the P-type semiconductor layer and prevent the P-type doping atoms from entering the active layer. In this embodiment, the value of the first doping concentration A is between 1E17 and 5E17 atoms / cm 3For example, the first doping concentration is 1E17 atoms / cm 3 The doping concentration of the P-type space layer 6031 is less than 1E17 atoms / cm in the direction away from the active layer 602. 3 Increased to 1E17 atoms / cm 3 Optionally, the material of the P-type space layer 6031 is Al x Ga 1-x InP, 0.5≤x≤0.8, the thickness of the P-type space layer 6031 is For example,

[0092] In an optional embodiment, the N-type semiconductor layer 601 includes an N-type cladding layer 6011. The material of the N-type cladding layer 6011 is AlInP, the thickness is between 0.5 μm and 4 μm, and the concentration of doped silicon can be in the range of 0.4E18 atoms / cm 3 ~2E18 atoms / cm 3 . Optionally, the N-type semiconductor layer 601 also includes an N-type space layer 6012. The N-type space layer 6012 is arranged between the N-type cladding layer 6011 and the active layer 603. The N-type space layer 6012 belongs to a non-actively doped space region, which can limit the diffusion of electrons and ensure that electrons can effectively recombine with holes in the active region to emit light. However, due to the diffusion of doped impurities in other layers, the N-type space layer 6012 has a certain doping concentration in the final product. In this embodiment, the material of the N-type space layer 6012 is Al x Ga 1-x InP, 0.5≤x≤0.8, thickness between

[0093] In an optional embodiment, the epitaxial stack structure further includes an etching stop layer 300. The etching stop layer 300 is disposed above the growth substrate 100. The etching stop layer 300 is used as an etching stop layer 300 for dry etching or wet etching. In this embodiment, the material of the etching stop layer 300 is GaInP, and the thickness is between The etching stop layer 300 is doped with silicon at a certain concentration.

[0094] In an optional embodiment, in order to eliminate the influence of the lattice defects of the growth substrate 100 on the semiconductor epitaxial layer 600, a buffer layer 200 may be formed between the substrate and the etching stop layer 300. The lattice quality of the buffer layer 200 is better than that of the growth substrate 100, which is conducive to eliminating the influence of the substrate lattice defects on the semiconductor epitaxial layer 600. The material of the buffer layer 200 may be one of GaAs, GaP or InP, and the thickness may be between

[0095] In an optional embodiment, the epitaxial stack structure 001 further includes an N-type ohmic contact layer 400, which is disposed above the etching stop layer 300 to form a good ohmic contact. In this embodiment, the material of the N-type ohmic contact layer 400 is GaAs, and the thickness is between The N-type ohmic contact layer 400 is doped with a certain concentration of silicon, for example, the doping concentration range may be 1E18 atoms / cm 3 ~10E18 atoms / cm 3 .

[0096] In an optional embodiment, the epitaxial stack structure 001 further includes an N-type current blocking layer 500 and an N-type current spreading layer 510. The N-type current blocking layer 500 and the N-type current spreading layer 510 are sequentially disposed on the N-type ohmic contact layer 400. The N-type current blocking layer 500 is used to prevent electron overflow, and the thickness of the current blocking layer is between The material is GaInP, and the doping concentration is less than 5E18 atoms / cm 3 The N-type current spreading layer 510 is used for current spreading. The material is AlGaInP and the thickness is between 1μm and 4μm. The concentration of doped silicon can be in the range of 0.4E18 atoms / cm 3 ~2E18 atoms / cm 3 .

[0097] In an optional embodiment, the epitaxial stack structure 001 further includes a transition layer 700, which is disposed above the P-type semiconductor layer 603 and is used for transition of lattice constants. In this embodiment, the material of the transition layer 700 is AlGaInP and the thickness is The doping concentration is 0.5E18atoms / cm 3 ~2E18 atoms / cm 3 .

[0098] In an optional embodiment, the epitaxial stack structure 001 further includes a P-type current spreading layer 800. In this embodiment, the P-type current spreading layer 800 is disposed on the transition layer 700. The material of the P-type current spreading layer 800 is GaP, the thickness is 0 μm to 12 μm, the doping impurity is Mg, and the doping concentration is 0.5E18 atoms / cm 3 ~2E18 atoms / cm 3 .

[0099] In an optional embodiment, the epitaxial stack structure 001 further includes a P-type ohmic contact layer 900. In this embodiment, the P-type ohmic contact layer 900 is disposed on the P-type current spreading layer 800. The material of the P-type ohmic contact layer 900 is GaP and the thickness is Its doping impurity is C, and the doping concentration is greater than 1E19atoms / cm 3 .

[0100] Example 2

[0101] This embodiment provides a light emitting diode, which includes the epitaxial stack structure 001 in Embodiment 1. The epitaxial stack structure 001 may include only the epitaxial layer 600 having the light emitting function in Embodiment 1, or may include the epitaxial layer 600 in Embodiment 1. Figure 1 The epitaxial stack structure 001 shown includes other structures besides the epitaxial layer 600. The epitaxial stack structure 001 includes other functional layers besides the epitaxial layer 600 having the light-emitting function. The light-emitting diode formed by the epitaxial stack structure 001 may be a vertical structure or a horizontal structure.

[0102] In one example of this embodiment, referring to Figure 5 , the light emitting diode is formed into a vertical structure. Specifically, the light emitting diode includes removing the growth substrate 100, the buffer layer 200 and the etching stop layer 300 on the basis of embodiment 1, exposing the N-type ohmic contact layer 400. An N-type electrode 1021 is formed on the N-type ohmic contact layer 400. In addition, a bonding layer 1000 is formed on the P-type ohmic contact layer 900 to bond the bonding substrate 1010 to form a connection with the epitaxial stack structure 001, and an electrode material is evaporated or sputtered on the bonding substrate 1010 to form a P-type electrode 1022. At this time, the bonding substrate 1010 is a conductive substrate.

[0103] In another example of this embodiment, referring to Figure 6, the light-emitting diode forms a horizontal structure. Specifically, the light-emitting diode includes removing the growth substrate 100, the buffer layer 200 and the etching stop layer 300 on the basis of Example 1, exposing the N-type ohmic contact layer 400. A step structure is formed on one side of the epitaxial stack structure 001 of the light-emitting diode (the side where the N-type ohmic contact layer 400 is located), and the step structure includes two mesas, and the first mesa exposes the N-type semiconductor layer 601, or other layers connected to the N-type semiconductor layer 601, such as the N-type ohmic contact layer 400. The second mesa exposes the P-type semiconductor layer 603 or other layers connected to the P-type semiconductor layer 603, such as the P-type ohmic contact layer 900. Subsequently, electrode materials are evaporated or sputtered on the first mesa and the second mesa, respectively, to form a P-type electrode 1021 and an N-type electrode 1022. Furthermore, on one side of the epitaxial stack structure 001 opposite to the step structure (the side where the P-type ohmic contact layer 900 is located), a bonding layer 1000 and a bonding substrate 1010 are also provided. In this case, the bonding substrate 1010 may be an insulating substrate.

[0104] Since the light-emitting diode in this embodiment includes the epitaxial stack structure 001 in Example 1, the P-type semiconductor layer in the epitaxial stack structure 001 includes a first doping layer with an increasing doping concentration in a direction away from the active layer. The first doping layer can buffer the diffusion of the P-type semiconductor layer from the high-concentration area (second doping layer) to the low-concentration area (active layer), thereby preventing P-type impurities from entering the active layer, causing excessive deviation of the recombination position of electrons and holes, and affecting the luminous efficiency and reliability of the light-emitting diode.

[0105] Example 3

[0106] This embodiment provides a light emitting device, such as Figure 7 As shown, the light emitting device 10 includes a circuit substrate 11 and at least one light emitting element 12 fixed to the circuit substrate 11, and the light emitting element 12 includes any one or more combinations of light emitting diodes provided in the above-mentioned embodiments 1 and 2 of the present application. One electrode of the light emitting diode is directly fixedly connected to the circuit layer 13 of the circuit substrate 11 through welding and other processes, and the other electrode is connected to the circuit layer 13 of the circuit substrate 11 through a gold wire through a wire bonding process. Because the light emitting device includes any one or more combinations of light emitting diodes provided in embodiments 1 and 2, it has a good light emitting effect and better reliability.

[0107] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A light emitting diode, characterized in that: include: An epitaxial stack structure, the epitaxial stack structure includes, from bottom to top, an N-type semiconductor layer, an active layer and a P-type semiconductor layer, the active layer is located between the N-type semiconductor layer and the P-type semiconductor layer, the P-type semiconductor layer includes a P-type cladding layer, the P-type cladding layer includes adjacent first doping layers and second doping layers, the first doping layer is close to the active layer, the doping concentration of the first doping layer increases from a first doping concentration on a side close to the active layer to a second doping concentration on a side away from the active layer, and the doping concentration of the second doping layer is greater than or equal to the second doping concentration.

2. The light emitting diode according to claim 1, characterized in that: The P-type semiconductor layer further comprises: The P-type space layer is disposed between the active layer and the P-type cladding layer, and the doping concentration of the P-type space layer increases from a first unintentional doping concentration to the first doping concentration along a direction away from the active layer.

3. The light emitting diode according to claim 2, characterized in that: The first unintentional doping concentration is in the range of 1E16 atoms / cm 3 ~1E17 atoms / cm 3 .

4. The light emitting diode according to claim 1 or 2, characterized in that: The value of the first doping concentration is between 1E17atoms / cm 3 ~5E17 atoms / cm 3 .

5. The light emitting diode according to claim 4, characterized in that: The value of the second doping concentration is greater than or equal to 5E17 atoms / cm 3 .

6. The light emitting diode according to claim 5, characterized in that: The doping concentration of the second doping layer is not greater than 2E18atoms / cm 3 .

7. The light emitting diode according to claim 4, characterized in that: The thickness of the first doping layer is t1, and the thickness of the second doping layer is t2. The thickness t1 of the first doping layer is greater than the thickness t2 of the second doping layer.

8. The light emitting diode according to claim 7, characterized in that: The relationship between the thickness of the first doping layer and the thickness of the second doping layer is: 1<t1 / t2<2.

9. The light emitting diode according to claim 1, characterized in that: The atomic radius of the doped atoms in the P-type semiconductor layer is smaller than the atomic radius of the group III element doped and substituted in the P-type semiconductor layer.

10. The light emitting diode according to claim 1, characterized in that: The doping atoms of the first doping layer and the second doping layer are Mg and / or Zn.

11. The light emitting diode according to claim 1, characterized in that: The thickness of the P-type cladding layer is between 0.3 μm and 4 μm.

12. The light emitting diode according to claim 2, characterized in that: The thickness of the P-type space layer is 13. The light emitting diode according to claim 1, characterized in that: The material of the active layer is AlGaInP material.

14. The light emitting diode according to claim 1, characterized in that: The materials of the first doping layer and the second doping layer are AlInP materials.

15. The light emitting diode according to claim 2, characterized in that: The material of the P-type space layer is Al x Ga (1-x) InP, where 0.5≤x≤0.

8.

16. The light emitting diode according to claim 1, characterized in that: The epitaxial stack structure further includes: A transition layer, disposed above the P-type cladding layer; A P-type current spreading layer, disposed above the transition layer; The P-type ohmic contact layer is arranged above the P-type current spreading layer.

17. The light emitting diode according to claim 1, characterized in that: The N-type semiconductor layer comprises: The N-type cladding layer has N-type doping and provides electrons for the active layer.

18. The light emitting diode according to claim 17, characterized in that: The N-type semiconductor layer further comprises: The N-type space layer is disposed between the N-type cladding layer and the active layer to block impurities from entering the active layer.

19. The light emitting diode according to claim 17, characterized in that: The epitaxial stack structure further includes: An N-type ohmic contact layer is disposed on a side of the N-type cladding layer away from the active layer; The N-type current blocking layer is arranged above the N-type ohmic contact layer and below the N-type cladding layer.

20. A light emitting device, characterized in that: The light emitting device comprises a circuit substrate and at least one light emitting element located on the circuit substrate, wherein the light emitting element comprises at least one light emitting diode according to any one of claims 1 to 19.

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