LED chip structure with dual-channel hole injection function and preparation method thereof

Abstract

The invention relates to an LED chip structure with a dual-channel hole injection function and a preparation method thereof. According to the structure, an intrinsic layer of a sandwich structure and an N-type GaN layer are epitaxially grown on a P-type GaN layer, namely, the GaN layer above a P region completely absorbs photons, photo-generated electrons and holes are generated after the material absorbs the photons, and the photo-generated holes can be re-injected into a quantum well and emit the photons through radiation recombination by adjusting the electric field of the part of the material, so that the light emitting efficiency is improved. Therefore, the problem that in a traditional method, the top GaN layer absorbs photons, but photo-generated holes are not effectively utilized is effectively solved. According to the invention, the utilization rate of photons at the top of the device can be obviously improved, so that the emergent light of the substrate is increased.

Description

Technical Field

[0001] The technical solution of the present invention relates to the field of semiconductor light-emitting devices, and specifically to a chip structure of an LED with a PIN structure and a preparation method thereof. Background Art

[0002] In recent years, deep-ultraviolet light-emitting diodes (DUV LEDs) have shown great application potential in many fields such as sensors, sterilization, air purification, water treatment, and optical communications. Compared with traditional mercury lamps, AlGaN-based DUV LEDs are not only non-toxic and environmentally friendly, but also have significant advantages such as small size, long life, fast response speed, and strong controllability. These advantages provide valuable opportunities for the research and development of related technologies and promote the widespread application of deep ultraviolet light sources in various industries.

[0003] For DUV LEDs with shorter emission wavelengths, they still face many physical mechanism and process technology challenges in achieving high electro-optical conversion efficiency (Wall-plug Efficiency, referred to as WPE) and high external quantum efficiency (External Quantum Efficiency, referred to as EQE). As the wavelength is further reduced, the EQE of DUV LEDs usually decreases, resulting in a significant decrease in its luminous efficiency. Among them, the low light extraction efficiency (Light Extraction Efficiency, referred to as LEE) is the main reason for this problem. In traditional LEDs, due to the difficulty of P-type doping of AlGaN materials, a good ohmic contact is usually achieved by using a heavily doped GaN layer on the top layer. However, the severe absorption of ultraviolet light by GaN materials and electrodes leads to low light extraction efficiency. This problem is particularly prominent in short-wavelength DUV LEDs. As the emission wavelength decreases, the absorption effect becomes more significant, further affecting the light output performance of the LED. Therefore, solving the material absorption problem and optimizing the light extraction efficiency have become key technical problems to improve the performance of short-wavelength DUV LEDs.

[0004] In order to improve the light extraction efficiency of the chip, patent CN119069586A proposed a method of using a photonic crystal structure, but its production process is complicated and has high requirements for the process. Another patent CN118610328A proposed a roughened surface technology, but because it uses dry etching or wet etching processes, it faces greater technical challenges. Document DOI: 10.1109 / LED.2024.3351857 proposed thinning the GaN layer to reduce light absorption, but it brings about problems such as current crowding. Therefore, in order to further improve the luminous efficiency of light-emitting diodes, including internal quantum efficiency and external quantum efficiency, it is particularly important to improve the luminous performance of LEDs by optimizing the epitaxial structure of light-emitting diodes. Summary of the invention

[0005] The purpose of the present invention is to solve the serious problem of the performance degradation of the device caused by light absorption in the traditional AlGaN-based LED, and propose an LED chip structure with a PIN structure and a preparation method thereof. After the photon is absorbed by the material, the energy is transferred to the electrons in the material, and the electrons are excited to jump from the valence band to the conduction band to form electron-hole pairs. However, in the traditional LED structure, the electric field near the absorption layer is not effectively regulated, resulting in the inability of the photogenerated carriers to be fully separated and effectively participate in the light-emitting process. The LED structure proposed by the present invention forms a sandwich structure by growing an AlGaN intrinsic layer and an N-type GaN layer on the P-type GaN cover layer of the traditional LED. By adjusting the thickness and composition of each intrinsic layer in the sandwich structure and the doping concentration of the N-type GaN layer, the internal electric field of the ultraviolet light absorbing material layer is accurately adjusted. By reasonably designing the electric field, the electron-hole pairs generated by the material absorbing photons can be effectively separated, so that the photogenerated carriers are re-injected into the multi-quantum well of the LED under the action of the electric field, and recombine with the electrons in the well to generate radiant light. In addition, the separation process of the photogenerated carriers under the electric field will also induce collision ionization, thereby further improving the photoelectric performance. According to the absorption characteristics of the material and the emission spectrum of the quantum well, the present invention can flexibly adjust the structure of the intrinsic layer and the doping concentration of the N-type GaN layer, and is suitable for ultraviolet LED application scenarios with different wavelengths.

[0006] The technical solution of the present invention is:

[0007] A chip structure of an LED having a dual-channel hole injection function, the structure comprising one of the following two structures:

[0008] The first type includes, from bottom to top, a substrate, a buffer layer, and an N-type electron injection layer; wherein the N-type electron injection layer is divided into two parts, the upper part is exposed, the area of ​​the exposed part is 5% to 90% of the lower part, and the thickness is 10% to 80% of the entire N-type electron injection layer;

[0009] The upper layer of the N-type electron injection layer is distributed with a multi-quantum well layer, a P-type electron blocking layer, a P-type semiconductor transmission layer, and a top P contact layer from bottom to top; the top P contact layer is a "sandwich-like" sandwich structure, that is, two intrinsic layers and an intrinsic sandwich layer sandwiched therein; the top of the sandwich structure is the top N contact layer; the middle of the top N contact layer is covered with an ohmic electrode; the middle of the exposed part of the lower layer of the N-type electron injection layer is also provided with an ohmic electrode;

[0010] Alternatively, the second type includes, from bottom to top, a substrate, a buffer layer, and an N-type electron injection layer; wherein the N-type electron injection layer is divided into two parts, the upper part is exposed, the area of ​​the exposed part is 5% to 90% of the lower part, and the thickness is 10% to 80% of the entire N-type electron injection layer;

[0011] The upper layer of the N-type electron injection layer is distributed with a multi-quantum well layer, a P-type electron blocking layer, a P-type semiconductor transmission layer, and a top P contact layer from bottom to top; the top P contact layer is an array-distributed "sandwich-like" sandwich structure, namely, two intrinsic layers and an intrinsic sandwich sandwiched therebetween; the array-distributed sandwich structure occupies 10% to 90% of the surface area of ​​the top P contact layer, and the top of the sandwich structure is the top N contact layer, together forming an array-distributed convex structure; the P-type ohmic electrode covers the surface, sidewalls and exposed top P contact layer of the convex structure;

[0012] An ohmic electrode is disposed in the middle of the exposed portion of the lower layer of the N-type electron injection layer;

[0013] The substrate is sapphire, Si, SiC, AlN, quartz glass or GaN.

[0014] The material of the buffer layer is Al x1 In y1 Ga 1-x1-y1 N, where 0≤x1≤1, 0≤y1≤1, 0≤1-x1-y1≤1, and the thickness is 10 to 2000 nm.

[0015] The material of the N-type electron injection layer is Al x1 In y1 Ga 1-x1-y1 N, where 0≤x1≤1, 0≤y1≤1, 0≤1-x1-y1≤1, and the thickness is 2 to 8 μm.

[0016] The material of the multi-quantum well layer is Al x1 In y1 Ga 1-x1-y1 N / A x2 In y2 Ga 1-x2-y2N, where 0≤x1≤1, 0≤y1≤1, 0≤1-x1-y1≤1, 0≤x2≤1, 0≤y2≤1, 0≤1-x2-y2≤1; where the quantum barrier Al x2 In y2 Ga 1-x2-y2 The thickness of N is 5 to 50 nm, and the quantum well Al x1 In y1 Ga 1-x1-y1 The thickness of N is 1 to 10 nm.

[0017] The material of the P-type electron blocking layer is Al x3 In y3 Ga 1-x3-y3 N, where 0≤x3≤1, 0≤y3≤1, 0≤1-x3-y3, and the thickness is 10 to 500 nm.

[0018] The Al of the P-type semiconductor transport layer x4 In y4 Ga 1-x4-y4 N, where 0≤x4≤1, 0≤y4≤1, 0≤1-x4-y4, and the thickness is 10 to 500 nm.

[0019] The Al of the top P contact layer x5 In y5 Ga 1-x5-y5 N, where 0≤x5≤1, 0≤y5≤1, 0≤1-x5-y5, the thickness is 1-500nm, and the material is heavily doped with P type.

[0020] The first intrinsic layer is made of Al x6 In y6 Ga 1-x6-y6 N, where 0≤x6≤1, 0≤y6≤1, 0≤1-x6-y6, thickness is 1 to 100 nm, and is not intentionally doped.

[0021] The intrinsic interlayer material is Al x7 In y7 Ga 1-x7-y7 N, where 0≤x7≤x6, y6≤y7≤1, 0≤1-x7-y7, thickness is 1 to 100 nm, and it is not intentionally doped.

[0022] The top N contact layer is made of Al x8 In y8 Ga 1-x8-y8 N, where 0≤x8≤1, 0≤y8≤1, 0≤1-x8-y8, thickness is 10~1000nm, material doping is N-type heavy doping, doping concentration is 10 18 -10 21 cm -3.

[0023] The material of the P-type ohmic electrode is Ni / Au, Cr / Au, Pt / Au or Ni / Al.

[0024] The material of the N-type ohmic electrode is N-type ohmic electrode Al / Au, Cr / Au or Ti / Al / Ti / Au.

[0025] The method for preparing the LED chip structure with dual-channel hole injection function is one of the following two methods:

[0026] Method 1 includes the following steps:

[0027] The first step is to bake the substrate at 950°C to 1400°C in a MOCVD (metal organic chemical vapor deposition) or MBE (molecular beam epitaxy) reactor;

[0028] The second step is to epitaxially grow a buffer layer with a thickness of 10 to 2000 nm on the surface of the substrate treated in the first step in a reaction furnace;

[0029] In the third step, in the reactor, an N-type electron injection layer with a thickness of 2 to 8 μm, a quantum barrier Al x2 In y2 Ga 1-x2-y2 The thickness of N is 5 to 50 nm, and the quantum well Al x1 In y1 Ga 1-x1-y1 N multi-quantum well layer with a thickness of 1 to 10 nm and a P-type electron blocking layer, a P-type semiconductor transport layer and a top P contact layer with a thickness of 100 to 500 nm;

[0030] Step 4, epitaxially growing a first intrinsic layer and an intrinsic interlayer with a thickness of 1 to 100 nm and a top N contact layer with a thickness of 10 to 1000 nm on the epitaxial layer obtained in the third step in a reaction furnace;

[0031] Step 5: Make steps by photolithography and dry etching to expose the N-type electron injection layer;

[0032] Step 6: evaporate and photolithography to produce an N-type ohmic electrode;

[0033] Thus, a chip structure of an LED with a dual-channel hole injection function is obtained;

[0034] Or method 2, a second method for preparing a chip structure of an LED having a dual-channel hole injection function, comprises the following steps:

[0035] The first step is to bake the substrate at 950°C to 1400°C in a MOCVD (metal organic chemical vapor deposition) or MBE (molecular beam epitaxy) reactor;

[0036] The second step is to epitaxially grow a buffer layer with a thickness of 10 to 2000 nm on the surface of the substrate treated in the first step in a reaction furnace;

[0037] In the third step, in the reactor, an N-type electron injection layer with a thickness of 2 to 8 μm, a quantum barrier Al x2 In y2 Ga 1-x2-y2 The thickness of N is 5 to 50 nm, and the quantum well Al x1 In y1 Ga 1-x1-y1 N multi-quantum well layer with a thickness of 1 to 10 nm and a P-type electron blocking layer, a P-type semiconductor transport layer and a top P contact layer with a thickness of 100 to 500 nm;

[0038] Step 4, epitaxially growing a first intrinsic layer and an intrinsic interlayer with a thickness of 1 to 100 nm and a top N contact layer with a thickness of 10 to 1000 nm on the epitaxial layer obtained in the third step in a reaction furnace;

[0039] Step 4: fabricating a step by photolithography and dry etching to expose the N-type electron injection layer;

[0040] Step 5: patterning the first intrinsic layer, the intrinsic interlayer and the top N-contact layer by photolithography and dry etching processes to partially expose the top P-contact layer;

[0041] Step 6: evaporate and photolithography to produce an N-type ohmic electrode made of Ti / Al / Ti / Au and a P-type ohmic electrode made of Ni / Au;

[0042] Thus, a chip structure of an LED with a dual-channel hole injection function is obtained.

[0043] The above-mentioned method for preparing the chip structure of an LED, the epitaxial growth process is completed by a metal organic chemical vapor deposition system (MOCVD), a molecular beam epitaxy system (MBE), a hydride vapor phase epitaxy (HVPE) or a plasma enhanced chemical vapor deposition system (PECVD) which are well known in the technical field.

[0044] In the above-mentioned method for preparing the chip structure of an LED, the P-type ohmic electrode and the N-type ohmic electrode are prepared by electron beam deposition (E-beam) or magnetron sputtering (Sputter) methods well known in the technical field.

[0045] The above-mentioned method for preparing the LED chip structure, the photolithography process, dry etching process and evaporation process are well known in the technical field.

[0046] The essential features of the present invention are:

[0047] Current technologies mainly focus on preventing materials from absorbing ultraviolet light to improve light extraction efficiency, and commonly used methods include patterning, dielectric cavities, etc. However, these methods usually involve complex process flows.

[0048] The present invention proposes an innovative solution to epitaxially grow an intrinsic layer and an N-type GaN layer on a traditional P-type GaN layer, that is, to allow the GaN layer above the P region to completely absorb photons. After the material absorbs photons, photogenerated electrons and holes are generated. By adjusting the electric field of this part of the material, the photogenerated holes can be re-injected into the quantum well and emit photons through radiation recombination, thereby effectively avoiding the problem in the traditional method that the top GaN layer absorbs photons but the photogenerated holes are not effectively utilized. Since the ultraviolet LED emits light from the substrate, this method can significantly improve the utilization rate of photons at the top of the device, thereby increasing the light output of the substrate.

[0049] In terms of electric field regulation, this patent proposes a sandwich structure (see Examples 2 and 3), which utilizes the polarization effect of AlGaN material and its built-in electric field. By adjusting the material composition and thickness of the intrinsic layer and the thickness of the N-type GaN above, the intensity and influence range of the electric field can be flexibly adjusted, thereby achieving effective control of photogenerated holes.

[0050] The beneficial effects of the present invention are:

[0051] (1) The LED structure proposed in the present invention grows an intrinsic layer and an N-type GaN layer on the P-type GaN capping layer of a conventional LED, and adjusts the thickness and composition of the intrinsic layer and the doping concentration of the N-type GaN layer to precisely control the internal electric field of the ultraviolet light absorbing material layer. The electron-hole pairs generated by the material absorbing photons are effectively separated, so that the photogenerated carriers are re-injected into the multi-quantum wells of the LED under the action of the electric field and recombine with the electrons in the quantum wells, thereby generating radiant light. As shown in the attached figure Fig.10 As shown, the hole concentration of the lower quantum well with the PIN structure of the present invention in Example 3 is increased by nearly 200% compared with that in Example 1 with the traditional structure.

[0052] (2) The LED structure of the present invention has extremely high flexibility, and can adjust the thickness of the intrinsic layer, the material composition and the doping concentration of the N-type GaN layer according to the absorption characteristics of the material and the emission spectrum of the quantum well. This flexible adjustment mechanism enables the LED structure of the present invention to adapt to the application requirements of ultraviolet LEDs of different wavelengths, especially in special fields such as ultraviolet light irradiation and disinfection.

[0053] (3) The preparation method proposed by the present invention is simple and easy to implement, the operation process is convenient, and it has strong repeatability, which can effectively reduce the instability in the production process. In addition, the preparation process of the present invention has low cost, and the materials and processes used are relatively common and mature, so it has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0055] Figure 1 This is a schematic diagram of the standard LED device structure in the prior art.

[0056] Figure 2 For standard LEDs, Figure 1 The product shown is a schematic diagram of the structure after steps are made by photolithography and dry etching to expose part of the N-type electron injection layer.

[0057] Figure 3 For standard LEDs, Figure 2 The product shown is a schematic structural diagram of a standard LED chip obtained by fabricating N-type electrodes and P-type electrodes through photolithography and metal evaporation, namely, Example 1.

[0058] Figure 4 This is a schematic diagram of the epitaxial structure of growing the first and second intrinsic layers, the intrinsic interlayer and the top N contact layer on the surface of the top P contact layer of the standard LED epitaxial wafer in Example 2.

[0059] Figure 5 This is a schematic diagram of the structure of the product in Example 2 after steps are made by photolithography and dry etching to expose a portion of the N-type electron injection layer.

[0060] Figure 6 This is a schematic structural diagram of an LED chip of the present invention obtained by fabricating an N-type electrode through photolithography and metal evaporation in Example 2.

[0061] Figure 7 This is a schematic diagram of the structure of the product in Example 3, in which the first and second intrinsic layers, the intrinsic interlayer and the top N-contact layer are patterned by photolithography and dry etching to expose a portion of the ohmic contact layer.

[0062] Figure 8 This is a schematic structural diagram of an LED chip of the present invention obtained by fabricating an N-type electrode and a P-type electrode through photolithography and metal evaporation in Example 3.

[0063] Fig. 9 The IV curves are those of the standard LED device, i.e., Example 1, and the device structure of Example 3 of the present invention.

[0064] Fig.10 The lateral one-dimensional hole concentration distribution in the last quantum well of the standard LED device, i.e., Example 1 and the device structure Example 3 of the present invention.

[0065] Among them, 101. substrate, 102. buffer layer, 103. N-type electron injection layer, 104. multi-quantum well layer, 105. P-type electron blocking layer, 106. P-type semiconductor transport layer, 107. top P-contact layer, 108. N-type ohmic electrode, 109. P-type ohmic electrode, 110. first intrinsic layer, 111. intrinsic interlayer, 112. top N-contact layer. DETAILED DESCRIPTION

[0066] The present invention is further described below in conjunction with embodiments and drawings, but this is not intended to limit the scope of protection of the claims of this application.

[0067] The preparation methods involved include photolithography, etching, metal evaporation, etc., which are all common operating processes, and the raw materials involved can be obtained through general channels.

[0068] Figure 1 The illustrated embodiment shows that the standard LED epitaxial wafer structure in the prior art includes: a substrate 101 , a buffer layer 102 , an N-type electron injection layer 103 , a multi-quantum well layer 104 , a P-type electron blocking layer 105 , a P-type semiconductor transport layer 106 , and a top P contact layer 107 .

[0069] Example 1 (Comparative Example)

[0070] The chip structure of an LED of the present embodiment includes, from bottom to top, a substrate 101, a buffer layer 102, an N-type electron injection layer 103, an N-type ohmic electrode 108 formed on the N-type electron injection layer 103, a multi-quantum well layer 104, a P-type electron blocking layer 105, a P-type semiconductor transport layer 106, a top P-contact layer 107, and a P-type ohmic electrode 109 formed on the top P-contact layer 107.

[0071] In the above, the substrate 101 is sapphire; the material of the buffer layer 102 is AlN, with a thickness of 2 μm; the material of the N-type electron injection layer 103 is Al 0.82 Ga 0.18 N, with a thickness of 4 μm; the material of the multi-quantum well layer 104 is Al 0.6 Ga 0.4 N / A 0.8 Ga 0.2 N, where the quantum barrier Al 0.8 Ga 0.2 The thickness of N is 9nm, and the quantum well Al 0.6 Ga 0.4The thickness of N is 1 nm; the material of the P-type electron blocking layer 105 is Al 0.82→0.67 Ga 0.18→0.33 N, with a thickness of 40 nm, and the material of the P-type semiconductor transport layer 106 is Al 0.67→0 Ga 0.33→0 N, with a thickness of 10nm. The material of the top P contact layer 107 is GaN, with a thickness of 2nm; the material of the N-type ohmic electrode 108 is Ti / Al / Ti / Au, with a thickness of 20 / 30 / 60 / 100nm. The material of the P-type ohmic electrode 109 is P-type ohmic electrode Ni / Au, with a thickness of 10 / 10nm.

[0072] The method for preparing the above-mentioned LED chip structure comprises the following steps:

[0073] In the first step, the sapphire substrate 101 is baked at 1200° C. in a reaction furnace to remove foreign matter on the surface of the substrate;

[0074] Step 2: In a reaction furnace, a buffer layer 102 with a thickness of 2 μm and made of AlN is epitaxially grown on the surface of the sapphire substrate 101 processed in the first step;

[0075] In the third step, in the reactor, an N-type electron injection layer 103 with a thickness of 4 μm and a multi-quantum well layer 104 made of Al are sequentially epitaxially grown on the buffer layer obtained in the second step. 0.6 Ga 0.4 N / A 0.8 Ga 0.2 N, where the quantum barrier Al 0.8 Ga 0.2 The thickness of N is 9nm, and the quantum well Al 0.6 Ga 0.4 The thickness of N is 1 nm; the material of the P-type electron blocking layer 105 is Al 0.82→0.67 Ga 0.18→ 0.33 N, with a thickness of 40 nm, and the material of the P-type semiconductor transport layer 106 is Al 0.67→0 Ga 0.33→0 N, with a thickness of 10 nm. The top P contact layer 107 is made of GaN, with a thickness of 2 nm.

[0076] Step 4: fabricate a step by photolithography and dry etching to expose the N-type electron injection layer 103 (see Figure 2 );

[0077] Step 5: evaporate and photolithography to produce an N-type ohmic electrode 108 made of Ti / Al / Ti / Au and a P-type ohmic electrode 109 made of Ni / Au (see the process). Figure 3 );

[0078] Thus, an LED chip structure of this embodiment is obtained.

[0079] In standard structure LED devices, the top layer is usually heavily doped with GaN to achieve good ohmic contact. However, the significant absorption of ultraviolet light by GaN materials and their electrodes leads to low light extraction efficiency. Therefore, to improve the optoelectronic performance of the device, solving the light absorption problem is a challenge that needs to be overcome.

[0080] Example 2

[0081] The first LED chip structure with dual-channel hole injection function includes, from bottom to top, a substrate 101, a buffer layer 102, and an N-type electron injection layer 103; wherein the N-type electron injection layer 103 is divided into two parts, the upper part is exposed, the area of ​​the exposed part is 5% to 90% of the lower part (specifically 30% in this embodiment), and the thickness is 10% to 80% of the entire N-type electron injection layer 103 (specifically 20% in this embodiment);

[0082] The upper layer of the N-type electron injection layer 103 is distributed with a P-type electron blocking layer 105, a P-type semiconductor transport layer 106, and a top P-contact layer 107 from bottom to top; the top P-contact layer 107 is a "sandwich-like" sandwich structure, that is, two intrinsic layers 110 and an intrinsic sandwich 111 sandwiched therebetween; the top of the sandwich structure is a top N-contact layer 112; the middle of the top N-contact layer 112 is covered with an ohmic electrode 108; the middle of the exposed part of the lower layer of the N-type electron injection layer 103 is also provided with an ohmic electrode 108;

[0083] In the above, the substrate 101 is sapphire, and the device is usually in a geometric shape such as square, rectangle, circle, etc. (specifically square in this embodiment), with a size of 350×350 μm. 2 The material of the buffer layer 102 is AlN, with a thickness of 2 μm; the material of the N-type electron injection layer 103 is Al 0.82 Ga 0.18 N, with a thickness of 4 μm; the material of the multi-quantum well layer 104 is Al 0.6 Ga 0.4 N / A 0.8 Ga 0.2 N, where the quantum barrier Al 0.8 Ga 0.2 The thickness of N is 9nm, and the quantum well Al 0.6 Ga 0.4 The thickness of N is 1 nm, and the number of quantum well pairs is 3; the material of the P-type electron blocking layer 105 is Al 0.82→0.67 Ga 0.18→0.33 N, with a thickness of 40 nm, and the material of the P-type semiconductor transport layer 106 is Al 0.67→0 Ga0.33→0 N, with a thickness of 10nm. The top P contact layer 107 is made of GaN, with a thickness of 2nm; the two intrinsic layers 110 are made of Al 0.1 Ga 0.9 N, with a thickness of 10 nm, the intrinsic interlayer 111 is made of GaN with a thickness of 30 nm, and the top N contact layer 112 is made of GaN with a doping concentration of 1×10 20 cm -3 The N-type ohmic electrode 108 is made of Ti / Al / Ti / Au and has a thickness of 20 / 30 / 60 / 100 nm.

[0084] The method for preparing the above-mentioned LED chip structure comprises the following steps:

[0085] In the first step, the sapphire substrate 101 is baked at 1200° C. in a reaction furnace to remove foreign matter on the surface of the substrate;

[0086] Step 2: In a reaction furnace, a buffer layer 102 with a thickness of 2 μm and made of AlN is epitaxially grown on the surface of the sapphire substrate 101 processed in the first step;

[0087] In the third step, in the reactor, an N-type electron injection layer 103 with a thickness of 4 μm is epitaxially grown on the buffer layer obtained in the second step; the material of the multi-quantum well layer 104 is Al 0.6 Ga 0.4 N / A 0.8 Ga 0.2 N, where the quantum barrier Al 0.8 Ga 0.2 The thickness of N is 9nm, and the quantum well Al 0.6 Ga 0.4 The thickness of N is 1 nm, and the number of quantum well pairs is 3; the material of the P-type electron blocking layer 105 is Al 0.82→0.67 Ga 0.18→0.33 N, with a thickness of 40 nm; the material of the P-type semiconductor transport layer 106 is Al 0.67→0 Ga 0.33→0 N, with a thickness of 10nm; the top P contact layer 107 is made of GaN, with a thickness of 2nm; the first intrinsic layer 110 is made of Al 0.1 Ga 0.9 N, with a thickness of 10 nm; the material of the intrinsic interlayer 111 is GaN, with a thickness of 30 nm; the material of the second intrinsic layer 110 is Al 0.1 Ga 0.9 N, with a thickness of 10 nm and the top N contact layer 112 is made of GaN with a doping concentration of 1×10 20 cm -3 , thickness is 100nm.

[0088] Step 4: fabricate a step by photolithography and dry etching to expose the N-type electron injection layer 103 (see Figure 5 );

[0089] Step 5: evaporate and photolithography to produce an N-type ohmic electrode 108 made of Ti / Al / Ti / Au (see the process for details). Figure 6 );

[0090] Thus, an LED chip structure of this embodiment is obtained.

[0091] Example 3

[0092] The structural parameters of the chip epitaxy in this example are consistent with those in Example 2.

[0093] The second LED chip structure with dual-channel hole injection function includes, from bottom to top, a substrate 101, a buffer layer 102, and an N-type electron injection layer 103; wherein the N-type electron injection layer 103 is divided into two parts, the upper part is exposed, the area of ​​the exposed part is 5% to 90% of the lower part (specifically 30% in this embodiment), and the thickness is 10% to 80% of the entire N-type electron injection layer 103 (specifically 20% in this embodiment);

[0094] The upper layer of the N-type electron injection layer 103 is distributed with a P-type electron blocking layer 105, a P-type semiconductor transport layer 106, and a top P contact layer 107 from bottom to top; on the top P contact layer 107 is an array-distributed "sandwich-like" sandwich structure, namely two intrinsic layers 110 and an intrinsic sandwich 111 sandwiched therebetween; the array-distributed sandwich structure occupies 10% to 90% (specifically 50% in this embodiment) of the surface area of ​​the top P contact layer 107, and the top of the sandwich structure is a top N contact layer 112, together forming an array-distributed convex structure; the P-type ohmic electrode 109 covers the surface, sidewalls and exposed top P contact layer 107 of the convex structure;

[0095] An ohmic electrode 108 is disposed in the middle of the exposed portion of the lower layer of the N-type electron injection layer 103;

[0096] The second method for preparing a chip structure of an LED having a dual-channel hole injection function comprises the following steps:

[0097] In the first step, the sapphire substrate 101 is baked at 1200° C. in a reaction furnace to remove foreign matter on the surface of the substrate;

[0098] Step 2: In a reaction furnace, a buffer layer 102 with a thickness of 2 μm and made of AlN is epitaxially grown on the surface of the sapphire substrate 101 processed in the first step;

[0099] In the third step, in the reactor, an N-type electron injection layer 103 with a thickness of 4 μm is epitaxially grown on the buffer layer obtained in the second step; the material of the multi-quantum well layer 104 is Al 0.6 Ga 0.4 N / A 0.8 Ga 0.2 N, where the quantum barrier Al 0.8 Ga 0.2 The thickness of N is 9nm, and the quantum well Al 0.6 Ga 0.4 The thickness of N is 1 nm; the material of the P-type electron blocking layer 105 is Al 0.82→0.67 Ga 0.18→ 0.33 N, with a thickness of 40 nm; the material of the P-type semiconductor transport layer 106 is Al 0.67→0 Ga 0.33→0 N, with a thickness of 10nm; the top P contact layer 107 is made of GaN, with a thickness of 2nm; the first and second intrinsic layers 110 are made of Al 0.1 Ga 0.9 N, with a thickness of 10 nm; the intrinsic interlayer 111 is made of GaN, with a thickness of 30 nm; and the top N contact layer 112 is made of GaN, with a thickness of 100 nm.

[0100] Step 4: fabricating a step by photolithography and dry etching to expose the N-type electron injection layer 103;

[0101] Step 5: patterning the first and second intrinsic layers 110, the intrinsic interlayer 111 and the top N-contact layer 112 by photolithography and dry etching processes, and partially exposing the top P-contact layer 107 (see the process). Figure 7 );

[0102] Step 6: evaporate and photolithography to produce an N-type ohmic electrode 108 made of Ti / Al / Ti / Au and a P-type ohmic electrode 109 made of Ni / Au (see the process). Figure 8 );

[0103] In the above embodiment, the epitaxial growth process is performed by a metal organic chemical vapor deposition system (MOCVD), a molecular beam epitaxy system (MBE), a hydride vapor phase epitaxy (HVPE) or a plasma enhanced chemical vapor deposition system (PECVD) known in the art. The P-type ohmic electrode 108 and the N-type ohmic electrode 109 are made by an electron beam deposition (E-beam) or magnetron sputtering (SPutter) method known in the art; the photolithography process, dry etching process and evaporation process are known in the art.

[0104] Fig. 9The IV characteristic curves of the standard LED device, namely, Example 1, and the device structure Examples 2 and 3 of the present invention, obtained by simulation calculation using Crosslight's APSYS software. As can be seen from the figure, the IV performance of the device in Example 2 of the present invention is relatively poor due to the PIN structure above increasing the built-in electric field and depletion region width of the device. However, Example 3 of the present invention can effectively improve the IV characteristics of the device by patterning the intrinsic semiconductor layer and the N-type GaN layer.

[0105] Fig.10 The lateral one-dimensional hole concentration distribution in the last quantum well of the standard LED device, i.e., Example 1, and the device structure Example 3 of the present invention. As can be seen from the figure, compared with the standard device, the hole concentration of the quantum well below the PIN structure is improved. This also further proves that the structure we proposed can effectively utilize photogenerated carriers, improve carrier injection, and thus improve the performance of the device.

[0106] Matters not covered by the present invention are known technologies.

Claims

1. A chip structure of an LED with a dual-channel hole injection function, characterized in that: The structure consists of one of the following two structures: The first type includes, from bottom to top, a substrate, a buffer layer, and an N-type electron injection layer; wherein the N-type electron injection layer is divided into two parts, the upper part is exposed, the area of ​​the exposed part is 5% to 90% of the lower part, and the thickness is 10% to 80% of the entire N-type electron injection layer; The upper layer of the N-type electron injection layer is distributed with a multi-quantum well layer, a P-type electron blocking layer, a hole transport layer, and a top P-contact layer from bottom to top; the top P-contact layer is a "sandwich-like" sandwich structure, that is, two intrinsic layers and an intrinsic sandwich layer sandwiched therein; the top of the sandwich structure is the top N-contact layer; the middle of the top N-contact layer is covered with an ohmic electrode; the middle of the exposed part of the lower layer of the N-type electron injection layer is also provided with an ohmic electrode; Alternatively, the second type includes, from bottom to top, a substrate, a buffer layer, and an N-type electron injection layer; wherein the N-type electron injection layer is divided into two parts, the upper part is exposed, the area of ​​the exposed part is 5% to 90% of the lower part, and the thickness is 10% to 80% of the entire N-type electron injection layer; The upper layer of the N-type electron injection layer is distributed with a multi-quantum well layer, a P-type electron blocking layer, a hole transport layer, and a top P contact layer from bottom to top. The top P contact layer is an array-distributed "sandwich-like" sandwich structure, namely two intrinsic layers and an intrinsic sandwich sandwiched therebetween; the array-distributed sandwich structure occupies 10% to 90% of the surface area of ​​the top P contact layer, and the top of the sandwich structure is the top N contact layer, together forming an array-distributed convex structure; the P-type ohmic electrode covers the surface, sidewalls and exposed top P contact layer of the convex structure; An ohmic electrode is disposed in the middle of the exposed portion of the lower layer of the N-type electron injection layer.

2. The LED chip structure with dual-channel hole injection function as claimed in claim 1, characterized in that: The substrate is sapphire, Si, SiC, AlN, quartz glass or GaN; The material of the buffer layer is Al x1 In y1 Ga 1-x1-y1 N, where 0≤x1≤1, 0≤y1≤1, 0≤1-x1-y1≤1, and the thickness is 10 to 2000 nm; The material of the N-type electron injection layer is Al x1 In y1 Ga 1-x1-y1 N, where 0≤x1≤1, 0≤y1≤1, 0≤1-x1-y1≤1, and the thickness is 2 to 8 μm; The material of the multi-quantum well layer is Al x1 In y1 Ga 1-x1-y1 N / A x2 In y2 Ga 1-x2-y2 N, where 0≤x1≤1, 0≤y1≤1, 0≤1-x1-y1≤1, 0≤x2≤1, 0≤y2≤1, 0≤1-x2-y2≤1; where the quantum barrier Al x2 In y2 Ga 1-x2-y2 The thickness of N is 5 to 50 nm, and the quantum well Al x1 In y1 Ga 1-x1-y1 The thickness of N is 1 to 10 nm; The material of the P-type electron blocking layer is Al x3 In y3 Ga 1-x3-y3 N, where 0≤x3≤1, 0≤y3≤1, 0≤1-x3-y3, thickness is 10~500nm; The Al of the P-type semiconductor transport layer x4 In y4 Ga 1-x4-y4 N, where 0≤x4≤1, 0≤y4≤1, 0≤1-x4-y4, thickness is 10 to 500 nm; The Al of the top P contact layer x5 In y5 Ga 1-x5-y5 N, where 0≤x5≤1, 0≤y5≤1, 0≤1-x5-y5, the thickness is 10-500nm, and the material is heavily doped with P type.

3. The LED chip structure with dual-channel hole injection function as claimed in claim 1, characterized in that: The first intrinsic layer is made of Al x6 In y6 Ga 1-x6-y6 N, where 0≤x6≤1, 0≤y6≤1, 0≤1-x6-y6, thickness is 1 to 100 nm, unintentional doping; The intrinsic interlayer material is Al x7 In y7 Ga 1-x7-y7 N, where 0≤x7≤x6, y6≤y7≤1, 0≤1-x7-y7, thickness is 1 to 100 nm, unintentional doping; The top N contact layer is made of Al x8 In y8 Ga 1-x8-y8 N, where 0≤x8≤1, 0≤y8≤1, 0≤1-x8-y8, thickness is 10~1000nm, material doping is N-type heavy doping, doping concentration is 10 18 -10 21 cm -3 .

4. The LED chip structure with dual-channel hole injection function as claimed in claim 1, characterized in that: The material of the P-type ohmic electrode is Ni / Au, Cr / Au, Pt / Au or Ni / Al; The material of the N-type ohmic electrode is N-type ohmic electrode Al / Au, Cr / Au or Ti / Al / Ti / Au.

5. The method for preparing a chip structure of an LED with a dual-channel hole injection function as claimed in claim 1, characterized in that: The steps include: Method 1 includes the following steps: The first step is to bake the substrate at 950°C to 1400°C in a MOCVD (metal organic chemical vapor deposition) or MBE (molecular beam epitaxy) reactor; The second step is to epitaxially grow a buffer layer with a thickness of 10 to 2000 nm on the surface of the substrate treated in the first step in a reaction furnace; In the third step, in the reactor, an N-type electron injection layer with a thickness of 2 to 8 μm, a quantum barrier Al x2 In y2 Ga 1-x2-y2 The thickness of N is 5 to 50 nm, and the quantum well Al x1 In y1 Ga 1-x1-y1 N multi-quantum well layer with a thickness of 1 to 10 nm and a P-type electron blocking layer, a P-type semiconductor transport layer and a top P contact layer with a thickness of 100 to 500 nm; Step 4, epitaxially growing a first intrinsic layer and an intrinsic interlayer with a thickness of 1 to 100 nm and a top N contact layer with a thickness of 10 to 1000 nm on the epitaxial layer obtained in the third step in a reaction furnace; Step 5: Make steps by photolithography and dry etching to expose the N-type electron injection layer; Step 6: evaporate and photolithography to produce an N-type ohmic electrode; Thus, a chip structure of an LED with a dual-channel hole injection function is obtained; Alternatively, method 2, a second method for preparing a chip structure of an LED having a dual-channel hole injection function, comprises the following steps: The first step is to bake the substrate at 950°C to 1400°C in a MOCVD (metal organic chemical vapor deposition) or MBE (molecular beam epitaxy) reactor; The second step is to epitaxially grow a buffer layer with a thickness of 10 to 2000 nm on the surface of the substrate treated in the first step in a reaction furnace; In the third step, in the reactor, an N-type electron injection layer with a thickness of 2 to 8 μm, a quantum barrier Al x2 In y2 Ga 1-x2-y2 The thickness of N is 5 to 50 nm, and the quantum well Al x1 In y1 Ga 1-x1-y1 N multi-quantum well layer with a thickness of 1 to 10 nm and a P-type electron blocking layer, a P-type semiconductor transport layer and a top P contact layer with a thickness of 100 to 500 nm; Step 4, epitaxially growing a first intrinsic layer and an intrinsic interlayer with a thickness of 1 to 100 nm and a top N contact layer with a thickness of 10 to 1000 nm on the epitaxial layer obtained in the third step in a reaction furnace; Step 4: fabricating a step by photolithography and dry etching to expose the N-type electron injection layer; Step 5: patterning the first intrinsic layer, the intrinsic interlayer and the top N-contact layer by photolithography and dry etching processes to partially expose the top P-contact layer; Step 6: evaporate and photolithography to produce an N-type ohmic electrode made of Ti / Al / Ti / Au and a P-type ohmic electrode made of Ni / Au; Thus, a chip structure of an LED with a dual-channel hole injection function is obtained.

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