Nitride light-emitting diode, preparation method thereof and light-emitting device

Abstract

The invention belongs to the technical field of semiconductors, and particularly relates to a nitride light-emitting diode and a preparation method thereof, and a light-emitting device, the nitride light-emitting diode at least comprises an epitaxial structure, the epitaxial structure comprises n epitaxial layers (n > = 2), the first epitaxial layer to the nth epitaxial layer are stacked in sequence, the first epitaxial layer comprises an n-type nitride layer, a first active layer and a first p-type nitride layer, each of the second epitaxial layer to the nth epitaxial layer includes a second active layer and a second p-type nitride layer; the tunneling layer is located between the two epitaxial layers, and the tunneling layer comprises a p-type contact layer and an n-type contact layer; the electrode structure comprises a first electrode and a second electrode, the first electrode is electrically connected with the n-type nitride layer, and the second electrode is electrically connected with the second p-type nitride layer of the nth epitaxial layer. According to the nitride light-emitting diode and the manufacturing method thereof, a single nitride light-emitting diode can be suitable for a high-current-density environment through a mode of connecting multiple epitaxial layers in series, and the nitride light-emitting diode has the effect of greatly improving the brightness and has extremely high industrial practical value.

Description

Nitride light-emitting diode, preparation method thereof, and light-emitting device Technical Field

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

[0002] GaN-based light-emitting diodes are widely used in daily life. Compared with traditional light sources, LEDs have the advantages of small size, low energy consumption, and long life. They are an important trend in the development of modern lighting and have been widely used in indicator lights, backlight sources, display screens and other fields.

[0003] Traditional GaN-based light-emitting diodes typically consist of an N-type nitride layer, an active layer, and a P-type nitride layer. The N-type nitride layer provides electrons, and the P-type nitride layer provides holes. The electrons and holes recombine in the active layer, releasing energy and emitting light. However, traditional light-emitting diodes consist of only a single epitaxial layer. Under high current density conditions, the external quantum effect (EQE) is significantly attenuated, and the brightness is also limited by the limitations of a single epitaxial layer, making it impossible to achieve higher brightness requirements at the same size and current density. Therefore, to meet the current high brightness requirements, multiple light-emitting diodes are usually connected in series for use in high-voltage (HV) products, but this requires a more complex structural design and is more expensive. Technical Solutions

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a nitride light-emitting diode suitable for high current density environments, which utilizes a design of multiple epitaxial layers connected in series to achieve high brightness.

[0005] According to a first aspect of the present invention, the present invention provides a nitride light-emitting diode, comprising:

[0006] An epitaxial structure comprising n epitaxial layers (n≥2), wherein a first epitaxial layer to an nth epitaxial layer are sequentially stacked, wherein the first epitaxial layer comprises an n-type nitride layer, a first active layer, and a first p-type nitride layer stacked in sequence, and each of the second epitaxial layer to the nth epitaxial layer comprises a second active layer and a second p-type nitride layer located on the second active layer;

[0007] a tunneling layer located between two adjacent epitaxial layers, the tunneling layer comprising a p-type contact layer and an n-type contact layer located on the p-type contact layer;

[0008] The electrode structure includes a first electrode and a second electrode, wherein the first electrode is electrically connected to the n-type nitride layer, and the second electrode is electrically connected to the second p-type nitride layer of the n-th epitaxial layer.

[0009] Preferably, the p-type doping concentration of the first p-type nitride layer is the same as or different from the p-type doping concentration of the second p-type nitride layer.

[0010] Preferably, the p-type doping concentration of the p-type contact layer is not lower than the p-type doping concentration of the first p-type nitride layer, and is not lower than the p-type doping concentration of the second p-type nitride layer.

[0011] Preferably, the p-type doping concentration of the p-type contact layer is twice or more than the p-type doping concentration of the first p-type nitride layer or the second p-type nitride layer.

[0012] Preferably, the doping concentration of the p-type contact layer is 1E 20 ~1E 21 atoms / cm 3 .

[0013] Preferably, the n-type doping concentration of the n-type contact layer is higher than the n-type doping concentration of the n-type nitride layer.

[0014] Preferably, the n-type doping concentration of the n-type contact layer is twice or more than the n-type doping concentration of the n-type nitride layer.

[0015] Preferably, the doping concentration of the n-type contact layer is 1E 20 ~1E 21 atoms / cm 3 .

[0016] Preferably, a V-shaped structure is formed in the n-type contact layer.

[0017] Preferably, the thickness of the n-type contact layer is not less than the thickness of the p-type contact layer.

[0018] Preferably, the thickness of the p-type contact layer is 10-100 angstroms, and the thickness of the n-type contact layer is 50-500 angstroms.

[0019] Preferably, the tunneling layer further includes an insertion layer, and the insertion layer is located between the p-type contact layer and the n-type contact layer.

[0020] Preferably, the insertion layer is an undoped or unintentionally doped nitride layer.

[0021] Preferably, the insertion layer is a single layer structure or a superlattice structure.

[0022] Preferably, the insertion layer includes a GaN layer or an InGaN layer or a GaN / InGaN superlattice.

[0023] Preferably, the thickness of the insertion layer is 20 to 200 angstroms.

[0024] Preferably, the tunneling layer further includes an n-type doped electron supply layer.

[0025] Preferably, the n-type doping concentration of the electron supply layer is lower than the n-type doping concentration of the n-type contact layer.

[0026] Preferably, the n-type doping concentration of the electron supply layer is 1E 19 ~1E 20 atoms / cm 3 .

[0027] Preferably, the carbon concentration of the electron supply layer is 1E 17 ~1E 18 atoms / cm 3 .

[0028] Preferably, the electron supply layer includes a GaN layer or an InGaN layer.

[0029] Preferably, the thickness of the electron supply layer is 200 to 1000 angstroms.

[0030] Preferably, a stress release layer is further included, and the stress release layer is located between the n-type nitride layer and the first active layer, and between the tunneling layer and the second active layer.

[0031] Preferably, an electron blocking layer is further included, and the electron blocking layer is located on the second active layer in the nth epitaxial layer.

[0032] According to a second aspect of the present invention, the present invention provides a method for preparing a nitride light-emitting diode, comprising the following steps:

[0033] Providing a substrate, and growing an epitaxial structure on the substrate, wherein the epitaxial structure includes n epitaxial layers (n≥2), and sequentially growing a first epitaxial layer to an nth epitaxial layer, wherein the first epitaxial layer includes an n-type nitride layer, a first active layer, and a first p-type nitride layer grown in sequence, and each of the second epitaxial layer to the nth epitaxial layer includes a second active layer and a second p-type nitride layer located on the second active layer;

[0034] growing a tunneling layer between two adjacent epitaxial layers at a low temperature, the tunneling layer comprising a p-type contact layer and an n-type contact layer located on the p-type contact layer;

[0035] The nth epitaxial layer is etched to the n-type nitride layer to form a first electrode production area, and a first electrode and a second electrode are respectively produced in the first electrode production area and on the surface of the nth epitaxial layer. The first electrode and the second electrode are respectively electrically connected to the n-type nitride layer and the second p-type nitride layer of the nth epitaxial layer.

[0036] Preferably, the method further includes the following steps: growing an insertion layer between the p-type contact layer and the n-type contact layer at a low temperature, and growing an electron supply layer on the tunneling layer at a low temperature.

[0037] According to a third aspect of the present invention, a light-emitting device includes the above-mentioned nitride light-emitting diode. Beneficial effects

[0038] By connecting multiple epitaxial layers in series, this invention enables a single nitride light-emitting diode to operate in high-current density environments. Furthermore, by eliminating the traditional n-type nitride layer from the second epitaxial layer to the nth epitaxial layer and utilizing a tunneling layer to transport carriers (electrons and holes) to the epitaxial structure, high brightness can be achieved within a relatively small area. The nitride light-emitting diode of this invention has been shown to increase luminance by at least 60%, demonstrating its high industrial practical value.

[0039] The light-emitting device described in the present invention includes the above-mentioned nitride light-emitting diode, and has the above-mentioned technical effects.

[0040] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained through the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In addition, the accompanying drawings are for description only and are not drawn to scale.

[0042] FIG1 is a schematic structural diagram of the epitaxial structure of a nitride light-emitting diode according to Example 1 of the present invention.

[0043] FIG2 is a schematic structural diagram of one of the nitride light-emitting diodes according to Example 1 of the present invention.

[0044] FIG3 is an enlarged schematic diagram of the n-type contact layer of Example 1 provided by the present invention.

[0045] FIG4 is a schematic structural diagram of a second nitride light-emitting diode according to Example 1 of the present invention.

[0046] FIG5 is a schematic structural diagram of the third nitride light-emitting diode according to Example 1 of the present invention.

[0047] FIG6 is a schematic structural diagram of a nitride light-emitting diode according to Example 2 of the present invention.

[0048] FIG7 is a schematic structural diagram of one of the nitride light-emitting diodes according to Example 3 of the present invention.

[0049] FIG8 is a schematic structural diagram of a second nitride light-emitting diode according to Example 3 of the present invention.

[0050] Figure annotation:

[0051] 1. First epitaxial layer; 2. Second epitaxial layer; n, nth epitaxial layer; 10. Epitaxial layer; 11. N-type nitride layer; 12. First active layer; 13. First p-type nitride layer; 21. Second active layer; 22. Second p-type nitride layer; 30. Tunneling layer; 31. P-type contact layer; 32. N-type contact layer; 321. V-type structure; 33. Insertion layer; 40. Electrode structure; 41. First electrode; 42. Second electrode; 50. Electron supply layer; 60. Stress release layer; 70. Electron blocking layer; 80. Substrate. Modes for Carrying Out the Invention

[0052] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and examples, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0053] Example 1

[0054] 1 and 2 , an embodiment of the present invention discloses a nitride light emitting diode, which includes at least: an epitaxial structure, a tunneling layer 30 and an electrode structure 40 .

[0055] Specifically, the epitaxial structure includes n epitaxial layers 10, stacked sequentially from the first epitaxial layer 1 to the nth epitaxial layer n. The number n of epitaxial layers 10 is ≥ 2, meaning the number of epitaxial layers 10 is at least 2, and may also be an integer such as 3, 4, or 5, without particular limitation in the present invention. By connecting multiple epitaxial layers 10 in series, a single nitride light-emitting diode is formed, thereby enhancing the light intensity of the light-emitting diode.

[0056] The first epitaxial layer 1 includes an n-type nitride layer 11, a first active layer 12, and a first p-type nitride layer 13 stacked in sequence, while each of the second epitaxial layer 2 through the nth epitaxial layer n includes a second active layer 21 and a second p-type nitride layer 22 located on the second active layer 21. The first epitaxial layer 1 of this embodiment differs from the remaining epitaxial layers above it in that it additionally includes an n-type nitride layer 11.

[0057] The n-type nitride layer 11 of this embodiment is doped with n-type impurities, such as Si, Ge, Sn, Se or Te, but the impurity types are not limited thereto, to provide electrons. Preferably, the material of the n-type nitride layer 11 is GaN, and the doped n-type impurity is Si, with a doping concentration of 1E 18 ~8E 19 atoms / cm 3 The n-type nitride layer 11 may be a single layer structure or a super lattice structure, and its thickness is 10000-40000 angstroms.

[0058] The first p-type nitride layer 13 and the second p-type nitride layer 22 are doped with p-type impurities, such as Mg, Zn, Ca, Sr, or Ba, but the impurity types are not limited thereto, to provide holes. Preferably, the first p-type nitride layer 13 and the second p-type nitride layer 22 are both made of GaN, and the p-type impurity doped is Mg, with a doping concentration of 5E 19 ~3E 20 atoms / cm 3 The first p-type nitride layer 13 and the second p-type nitride layer 22 have the same or different p-type doping concentrations. The second p-type nitride layer 22 of the nth epitaxial layer n further includes an ohmic contact layer (not shown in the figure). The ohmic contact layer is highly doped, for example, with a p-type doping concentration higher than 1×10 20 atoms / cm 3 , forming an ohmic contact with the second electrode 42.

[0059] The first active layer 12 and the second active layer 21 are both regions that actually emit light in the light-emitting diode, and are both regions that provide light radiation for the recombination of electrons and holes. By adjusting the composition ratio of the semiconductor materials in the active layer, it is expected that different wavelengths of light will be radiated. The active layer includes a well layer and a barrier layer, wherein the barrier layer has a larger band gap than the well layer. The active layer can be a periodic structure of a single quantum well or multiple quantum wells. In this embodiment, it is preferred that the first active layer 12 and the second active layer 21 are both periodic structures of multiple quantum wells. Specifically, the active layer includes 5 to 18 quantum well structures, and the thickness of a single quantum well structure is between 100 and 170 angstroms. Among them, the single quantum well structure is an InGaN well layer and a GaN barrier layer, or an InGaN well layer and an AlGaN barrier layer.

[0060] A tunneling layer 30 is located between two adjacent epitaxial layers 10. A tunneling layer 30 is required between each pair of epitaxial layers 10 and includes a p-type contact layer 31 and an n-type contact layer 32 located on the p-type contact layer 31. The tunneling layer 30 forms a tunneling junction between the p-type contact layer 31 and the n-type contact layer 32, facilitating the transfer of excess carriers (electrons and holes) into different epitaxial layers 10 for radiative recombination.

[0061] In addition to forming a tunnel junction that is conducive to carrier migration, the tunnel layer 30 can also provide holes and electrons for the epitaxial layer 10, especially providing sufficient electrons for the second epitaxial layer 2 to the nth epitaxial layer n to make up for the problem of lack of electrons provided by the traditional n-type nitride layer, while also avoiding the instability of relying solely on overflow to provide electrons.

[0062] The p-type contact layer 31 is doped with p-type impurities, such as Mg, Zn, Ca, Sr, or Ba, but the impurity types are not limited thereto. The p-type impurity is primarily used to provide holes for the epitaxial layer 10 immediately below it. In this embodiment, Mg is preferably used as the p-type impurity. The n-type contact layer 32 is doped with n-type impurities, such as Si, Te, Ge, Sn, Pb, Sb, Bi, or Po, but the impurity types are not limited thereto. The n-type impurity is primarily used to provide electrons for the epitaxial layer 10 immediately above it. In this embodiment, Si or Te is preferably used as the n-type impurity.

[0063] Both the p-type contact layer 31 and the n-type contact layer 32 have high doping concentrations to increase the number of holes and electrons and their injection efficiency. Preferably, the p-type doping concentration of the p-type contact layer 31 is no less than the p-type doping concentration of the first p-type nitride layer 13 and no less than the p-type doping concentration of the second p-type nitride layer 22. The n-type doping concentration of the n-type contact layer 32 is higher than the n-type doping concentration of the n-type nitride layer 11.

[0064] More preferably, the p-type doping concentration of the p-type contact layer 31 is 2 times or more than the p-type doping concentration of the first p-type nitride layer 13 or the second p-type nitride layer 22. The n-type doping concentration of the n-type contact layer 32 is 2 times or more than the n-type doping concentration of the n-type nitride layer 11. Optimally, the doping concentration of the p-type contact layer 31 is 1E 20 ~1E 21 atoms / cm 3 , the doping concentration of the n-type contact layer 32 is 1E 20 ~1E 21 atoms / cm 3 .

[0065] Optionally, the p-type contact layer 31 is made of GaN or InGaN, and the n-type contact layer 32 is made of GaN or InGaN. The thickness of the p-type contact layer 31 is 10 to 100 angstroms, and the thickness of the n-type contact layer 32 is 50 to 500 angstroms. Preferably, the thickness of the n-type contact layer 32 is not less than that of the p-type contact layer 31, and the doping concentration is adjusted to further improve electron injection efficiency.

[0066] The n-type contact layer 32 has a v-shaped structure 321 therein. The v-shaped structure 321 starts from the n-type contact layer 32 and extends upward to form a larger v-shaped structure. This can improve the luminous efficiency of the epitaxial layer 10 located thereover and can also release some stress during the growth process, as shown in FIG3 .

[0067] Continuing with reference to FIG2 , the electrode structure 40 includes a first electrode 41 and a second electrode 42 , wherein the first electrode 41 is disposed on the n-type nitride layer 11 , and the second electrode 42 is disposed on the n-th epitaxial layer n, so that the first electrode 41 is electrically connected to the n-type nitride layer 11 , and the second electrode 42 is electrically connected to the second p-type nitride layer 22 of the n-th epitaxial layer n.

[0068] The first electrode 41 and the second electrode 42 are both metal electrodes. The material of the first electrode 41 and the second electrode 42 is selected from one or a combination of the group consisting of Ni, Pd, Pt, Cr, Au, Ti, Ag, Al, Ge, W, SiW, Ta, AuZn, AuBe, AuGe, and AuGeNi. Typically, the first electrode 41 and the second electrode 42 are formed by depositing multiple metal layers. The bottom layer of the electrode can be a metal with good adhesion, such as Cr, and the outermost layer of the electrode can be a metal with good conductivity, such as Au.

[0069] To improve the growth quality and performance of the light-emitting diode and to relieve stress generated during the growth process, this embodiment further includes a stress relief layer 60. This stress relief layer 60 is located between the n-type nitride layer 11 and the first active layer 12, and between the tunneling layer 30 and the second active layer 21. For details, see Figure 4 . The stress relief layer 60 can be a superlattice structure comprising alternating well layers and barrier layers. The well layers are typically layers of an In-containing material, with an In content lower than that of the active layer. In this embodiment, the well layers are preferably InGaN layers, and the barrier layers are preferably GaN layers.

[0070] To prevent electron overflow in the topmost epitaxial layer 10 (nth epitaxial layer n), which could affect the light-emitting diode's luminous intensity, this embodiment further includes an electron blocking layer 70, preferably an AlGaN layer, on the second active layer 21 within the nth epitaxial layer n. The remaining epitaxial layers 10 require electron overflow to provide excess carriers to the various epitaxial layers 10, so an electron blocking layer is not required to prevent electron overflow. For details, see Figure 4.

[0071] In order to more conveniently and clearly describe the content and principle of the invention of this embodiment, a specific implementation will be used as an example for detailed description below. The structures and principles of other implementations can be understood with reference to this implementation, as follows:

[0072] In a specific implementation, the epitaxial structure of the nitride light-emitting diode includes two epitaxial layers 10 (n=2). As shown in FIG5 , the nitride light-emitting diode includes: an epitaxial structure including two epitaxial layers 10, wherein the first epitaxial layer 1 to the second epitaxial layer 2 are sequentially stacked, wherein the first epitaxial layer 1 includes an n-type nitride layer 11, a first active layer 12, and a first p-type nitride layer 13 stacked in sequence, and the second epitaxial layer 2 includes a second active layer 21 and a second active layer 22 located at the second active layer 23. a second p-type nitride layer 22 on the epitaxial layer 21; a tunneling layer 30, located between the first epitaxial layer 1 and the second epitaxial layer 2, and located on the first epitaxial layer 1, the tunneling layer 30 includes a p-type contact layer 31 and an n-type contact layer 32 located on the p-type contact layer 31; an electrode structure 40, including a first electrode 41 and a second electrode 42, the first electrode 41 is electrically connected to the n-type nitride layer 11, and the second electrode 42 is electrically connected to the second p-type nitride layer 22 of the second epitaxial layer 2.

[0073] The tunneling layer 30 forms a tunneling junction through the p-type contact layer 31 and the n-type contact layer 32 , so that excess carriers (electrons and holes) can better enter the other epitaxial layer 10 to complete radiation recombination.

[0074] It should be noted that in this specific implementation, the holes in the first active layer 12 within the first epitaxial layer 1 originate from holes provided by the first p-type nitride layer 13 and the p-type contact layer 31, while the electrons originate from electrons provided by the n-type nitride layer 11. The holes in the second active layer 21 within the second epitaxial layer 2 originate from holes provided by the second p-type nitride layer 22. However, since the second epitaxial layer 2 lacks a traditional n-type nitride layer, it cannot obtain electrons from this epitaxial layer. Instead, it relies on excess electrons overflowing from the first epitaxial layer 1 and electrons provided by the n-type contact layer 32.

[0075] In this specific implementation, the second epitaxial layer 2 does not utilize a traditional n-type nitride layer. On the one hand, growing a traditional n-type nitride layer requires high temperatures, which can damage the In component within the underlying first active layer 12 of the first epitaxial layer 1, thereby affecting the brightness of the entire LED. On the other hand, a traditional n-type nitride layer that is too thick will create a longer path for electrons overflowing from the first epitaxial layer 1 to enter the light-emitting region of the second epitaxial layer 2. This reduces the number of overflow electrons entering the second epitaxial layer 2 (second active layer 21), weakening radiative recombination and ultimately affecting the overall luminous efficiency.

[0076] In this embodiment, to improve the growth quality and performance of the LED and to relieve stress generated during the growth process, two stress relief layers 60 are provided. These stress relief layers 60 are located between the n-type nitride layer 11 and the first active layer 12, and between the tunneling layer 30 and the second active layer 21, respectively. Furthermore, to prevent electron overflow from the second epitaxial layer 2 and thus affect the LED's luminous intensity, an electron blocking layer 70 is provided on the second active layer 21 within the second epitaxial layer 2. For details, see FIG. 5 . The stress relief layers 60 and electron blocking layers 70 can be configured according to actual production requirements.

[0077] This embodiment also provides a method for preparing the above-mentioned nitride light-emitting diode, and the method for preparing the nitride light-emitting diode comprises the following steps:

[0078] A substrate 80 is provided; the substrate 80 is sufficiently thick to support the layers and structures grown thereon. The substrate 80 can be made of a conductive or insulating material and can be made of any one or a combination of materials selected from Al2O3, SiO2, SiC, Si, GaAs, GaN, and semiconductor materials with a lattice constant close to that of nitrides. To improve the light extraction efficiency of the substrate 80, it can also be patterned to form a series of concave and convex structures on its surface. This embodiment of the present invention is not particularly limited in this regard, and the substrate 80 can be thinned or removed in subsequent processes. If the substrate 80 is retained after subsequent processes, a buffer layer (not shown) can be grown between the substrate 80 and the first epitaxial layer 1 to avoid lattice mismatch defects.

[0079] Growing an epitaxial structure on a substrate 80, the epitaxial structure including n epitaxial layers 10 (n ≥ 2), wherein a first epitaxial layer 1 to an n-th epitaxial layer n are grown in sequence, wherein the first epitaxial layer 1 includes an n-type nitride layer 11, a first active layer 12, and a first p-type nitride layer 13 grown in sequence, and each epitaxial layer from the second epitaxial layer 2 to the n-th epitaxial layer n includes a second active layer 21 and a second p-type nitride layer 22 located on the second active layer 21;

[0080] A tunneling layer 30 is grown between two adjacent epitaxial layers 10 , wherein the tunneling layer 30 includes a p-type contact layer 31 and an n-type contact layer 32 located on the p-type contact layer 31 ;

[0081] All epitaxial layers 10 and the tunneling layer 30 are grown using MOCVD. An n-type impurity source is introduced during the growth of the n-type nitride layer 11 and the n-type contact layer 32, while a p-type impurity source is introduced during the growth of the first p-type nitride layer 13, the p-type contact layer 31, and the second p-type nitride layer 22. The tunneling layer 30 is grown using a low-temperature growth process, with temperatures ranging from 700°C to 900°C.

[0082] The nth epitaxial layer n is etched to form a first electrode fabrication area on the n-type nitride layer 11, and a first electrode 41 and a second electrode 42 are fabricated on the first electrode fabrication area and on the surface of the nth epitaxial layer n, respectively. The first electrode 41 and the second electrode 42 are electrically connected to the n-type nitride layer 11 and the second p-type nitride layer 22 of the nth epitaxial layer n, respectively.

[0083] Specifically, a portion of the epitaxial structure is removed from top to bottom through an etching process to form a stepped structure (MESA), exposing a portion of the upper surface of the n-type nitride layer 11. A first electrode 41 is formed on the exposed upper surface of the n-type nitride layer 11, and a second electrode 42 is formed on the remaining second p-type nitride layer 22 of the n-th epitaxial layer n. The etching process may include plasma dry etching or wet etching using a mixed acid solution. The first electrode 41 and the second electrode 42 may be formed by vapor deposition.

[0084] The nitride light-emitting diode of this embodiment breaks away from the traditional single epitaxial layer structure and employs multiple epitaxial layers 10 connected in series. This allows a single nitride light-emitting diode to easily handle high current density conditions and achieve high brightness within a relatively small area. This makes it a viable alternative to traditional high-voltage HV products (which utilize multiple light-emitting diodes in series), which are complex and expensive. Furthermore, this embodiment eliminates the traditional n-type nitride layers in the second epitaxial layer 2 through the nth epitaxial layer n, reducing production costs and breaking the traditional notion that electrons can only be supplied by the epitaxial layer itself. The tunneling layer 30 located between the two epitaxial layers 10 provides an optimal migration environment for charge carriers, effectively utilizing electrons overflowing from the epitaxial layer 10 and supplying them to the other epitaxial layers. Furthermore, the tunneling layer 30 itself can provide additional holes and electrons to the epitaxial layer 10, thereby improving the radiative recombination efficiency of all epitaxial layers 10 and significantly boosting the overall brightness of the light-emitting diode.

[0085] Example 2

[0086] 6 , this embodiment shares many features with Example 1. The common features will not be described here one by one, and only the differences will be described. This embodiment differs from Example 1 in that tunneling layer 30 further includes an insertion layer 33 located between p-type contact layer 31 and n-type contact layer 32.

[0087] During the fabrication process of the p-type contact layer 31 and the n-type contact layer 32, cross-contamination occurs between the p-type contact layer 31 and the n-type contact layer 32, resulting in an unclear interface between the p-type contact layer 31 and the n-type contact layer 32, which in turn affects the brightness of the nitride light-emitting diode. Therefore, in this embodiment, an insertion layer 33 is provided between the p-type contact layer 31 and the n-type contact layer 32 to improve the unclear interface.

[0088] Insertion layer 33 is relatively thin, preferably between 20 and 200 angstroms. Insertion layer 33 utilizes an undoped nitride layer, preferably GaN or InGaN. Other materials may have the disadvantage of high voltage. In this embodiment, insertion layer 33 has a single layer structure or a superlattice structure. Specifically, insertion layer 33 includes a GaN layer, an InGaN layer, or a GaN / InGaN superlattice.

[0089] This embodiment also provides a method for preparing the above-mentioned nitride light-emitting diode.

[0090] The method for preparing the nitride light-emitting diode of this embodiment is substantially the same as the method in Embodiment 1, except that it further comprises: growing an insertion layer 33 between the p-type contact layer 31 and the n-type contact layer 32 .

[0091] The insertion layer 33 is also grown using the MOCVD method. When the insertion layer 33 begins to grow, the impurity source is turned off and a low temperature environment of 700-900° C. is used to grow the insertion layer 33.

[0092] It should be noted that because the p-type contact layer 31 is grown before the insertion layer 33, p-type impurities are introduced during the growth of the p-type contact layer 31. After the p-type contact layer 31 is grown, a small amount of p-type impurities may remain in the cavity of the growth equipment. Therefore, although no doping is performed during the growth of the insertion layer 33, the residual impurities in the cavity may affect the insertion layer 33, resulting in a very small amount of p-type doping. However, the insertion layer 33 is essentially an unintentionally doped nitride layer.

[0093] Example 3

[0094] 7 and 8 , this embodiment shares many features with Embodiment 1 or 2. The common features will not be described individually here, and only the differences will be described. This embodiment differs from Embodiment 1 or 2 in that an n-type doped electron supply layer 50 is further included on the tunneling layer 30.

[0095] By adding an electron supply layer 50 and performing n-type doping on the electron supply layer 50, more electrons are provided to the epitaxial layer 10 located above it, thereby improving the electron injection efficiency and further improving the luminous efficiency of the entire light-emitting diode. Among them, the n-type doping concentration of the electron supply layer 50 is higher than the n-type doping concentration of the n-type nitride layer 11 and lower than the n-type doping concentration of the n-type contact layer 32. Preferably, the n-type doping concentration of the electron supply layer 50 is 1E 19 ~1E 20 atoms / cm 3 .

[0096] The electron supply layer 50 includes a GaN layer or an InGaN layer, wherein the doping with an In component helps the n-type contact layer 32 to complete the development of the V-shaped structure 321. Regarding the thickness of the electron supply layer 50, this embodiment only requires a relatively thin thickness. Specifically, the thickness of the electron supply layer 50 is preferably 200 to 1000 angstroms.

[0097] This embodiment also provides a method for preparing the above-mentioned nitride light-emitting diode.

[0098] The method for preparing the nitride light-emitting diode of this embodiment is substantially the same as the method in Embodiment 1 or Embodiment 2, except that it further comprises: growing an electron supply layer 50 on the tunneling layer 30 .

[0099] The electron supply layer 50 is also grown using the MOCVD method in a low temperature environment ranging from 700 to 900°C. Since the growth temperature has a positive relationship with the carbon concentration of the growth layer, the carbon concentration in the electron supply layer 50 is relatively low. Specifically, the carbon concentration of the electron supply layer 50 is 1E 17 ~1E 18 atoms / cm 3 .

[0100] Example 4

[0101] This embodiment also provides a light-emitting device that utilizes the nitride light-emitting diode provided by any of the above embodiments. The light-emitting device can be, for example, a white light illumination device, a backlight display device, a car light, a flashlight, a projection lamp, a stage lamp, or the like. This light-emitting device has the sufficient light output and brightness of the nitride light-emitting diode with multiple epitaxial layers 10 connected in series in the above embodiments, meeting the requirements of high brightness, high voltage, and low cost.

[0102] It should be noted that the above embodiments are only used to illustrate the present invention, and are not used to limit the present invention. Those skilled in the art can make various modifications and changes to the present invention without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention. The scope of patent protection of the present invention should be limited to the scope of the claims.

Claims

1. A nitride light-emitting diode, characterized in that include: An epitaxial structure comprising n epitaxial layers (n≥2), wherein a first epitaxial layer to an nth epitaxial layer are sequentially stacked, wherein the first epitaxial layer comprises an n-type nitride layer, a first active layer, and a first p-type nitride layer stacked in sequence, and each of the second epitaxial layer to the nth epitaxial layer comprises a second active layer and a second p-type nitride layer located on the second active layer; a tunneling layer located between two adjacent epitaxial layers, the tunneling layer comprising a p-type contact layer and an n-type contact layer located on the p-type contact layer; The electrode structure includes a first electrode and a second electrode, wherein the first electrode is electrically connected to the n-type nitride layer, and the second electrode is electrically connected to the second p-type nitride layer of the n-th epitaxial layer.

2. The nitride light-emitting diode according to claim 1, characterized in that: The p-type doping concentration of the first p-type nitride layer is the same as or different from the p-type doping concentration of the second p-type nitride layer.

3. The nitride light-emitting diode according to claim 1, characterized in that The p-type doping concentration of the p-type contact layer is not lower than the p-type doping concentration of the first p-type nitride layer, and is not lower than the p-type doping concentration of the second p-type nitride layer.

4. The nitride light-emitting diode according to claim 1, characterized in that: The p-type doping concentration of the p-type contact layer is twice or more than the p-type doping concentration of the first p-type nitride layer or the second p-type nitride layer.

5. The nitride light-emitting diode according to claim 1, characterized in that The doping concentration of the p-type contact layer is 1E 20 ~1E 21 atoms / cm 3 .

6. The nitride light-emitting diode according to claim 1, characterized in that The n-type doping concentration of the n-type contact layer is higher than the n-type doping concentration of the n-type nitride layer.

7. The nitride light-emitting diode according to claim 1, characterized in that: The n-type doping concentration of the n-type contact layer is twice or more than the n-type doping concentration of the n-type nitride layer.

8. The nitride light-emitting diode according to claim 1, wherein: The doping concentration of the n-type contact layer is 1E 20 ~1E 21 atoms / cm 3 .

9. The nitride light-emitting diode according to claim 1, characterized in that A V-shaped structure is formed in the n-type contact layer.

10. The nitride light-emitting diode according to claim 1, characterized in that The thickness of the n-type contact layer is not less than that of the p-type contact layer.

11. The nitride light-emitting diode according to claim 1 or 10, characterized in that: The thickness of the p-type contact layer is 10-100 angstroms, and the thickness of the n-type contact layer is 50-500 angstroms.

12. The nitride light-emitting diode according to claim 1, characterized in that: The tunneling layer further includes an insertion layer located between the p-type contact layer and the n-type contact layer.

13. The nitride light-emitting diode according to claim 12, characterized in that: The insertion layer is a non-doped or unintentionally doped nitride layer.

14. The nitride light-emitting diode according to claim 12, characterized in that: The insertion layer is a single layer structure or a super lattice structure.

15. The nitride light-emitting diode according to claim 13 or 14, characterized in that: The insertion layer includes a GaN layer or an InGaN layer or a GaN / InGaN superlattice.

16. The nitride light-emitting diode according to claim 12, wherein: The thickness of the insertion layer is 20 to 200 angstroms.

17. The nitride light-emitting diode according to claim 1, characterized in that The tunneling layer also includes an n-type doped electron supply layer.

18. The nitride light-emitting diode according to claim 17, characterized in that The n-type doping concentration of the electron supply layer is lower than the n-type doping concentration of the n-type contact layer.

19. The nitride light-emitting diode according to claim 17, wherein: The n-type doping concentration of the electron supply layer is 1E 19 ~1E 20 atoms / cm 3 .

20. The nitride light emitting diode according to claim 17, wherein The carbon concentration of the electron supply layer is 1E 17 ~1E 18 atoms / cm 3 .

21. The nitride light-emitting diode according to claim 17, wherein: The electron supply layer includes a GaN layer or an InGaN layer.

22. The nitride light-emitting diode according to claim 17, wherein: The thickness of the electron supply layer is 200 to 1000 angstroms.

23. The nitride light-emitting diode according to claim 1, characterized in that The invention further includes a stress release layer, wherein the stress release layer is located between the n-type nitride layer and the first active layer, and between the tunnel layer and the second active layer.

24. The nitride light-emitting diode according to claim 1, characterized in that The method further includes an electron blocking layer, wherein the electron blocking layer is located on the second active layer in the n-th epitaxial layer.

25. A method for preparing a nitride light-emitting diode, characterized in that: The steps include: Providing a substrate, and growing an epitaxial structure on the substrate, wherein the epitaxial structure includes n epitaxial layers (n≥2), and sequentially growing a first epitaxial layer to an nth epitaxial layer, wherein the first epitaxial layer includes an n-type nitride layer, a first active layer, and a first p-type nitride layer grown in sequence, and each of the second epitaxial layer to the nth epitaxial layer includes a second active layer and a second p-type nitride layer located on the second active layer; growing a tunneling layer between two adjacent epitaxial layers at a low temperature, the tunneling layer comprising a p-type contact layer and an n-type contact layer located on the p-type contact layer; The nth epitaxial layer is etched to the n-type nitride layer to form a first electrode production area, and a first electrode and a second electrode are respectively produced in the first electrode production area and on the surface of the nth epitaxial layer. The first electrode and the second electrode are respectively electrically connected to the n-type nitride layer and the second p-type nitride layer of the nth epitaxial layer.

26. The method for preparing a nitride light-emitting diode according to claim 25, wherein: The following steps are also included: An insertion layer is grown between the p-type contact layer and the n-type contact layer at low temperature, and an electron supply layer is grown on the tunneling layer at low temperature.

27. A light emitting device, characterized in that: It comprises the nitride light-emitting diode according to any one of claims 1 to 24.

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