Deep ultraviolet led structure, method of manufacturing the same, and light emitting device

Abstract

The application belongs to the technical field of deep ultraviolet LED, and particularly relates to a deep ultraviolet LED structure, a preparation method thereof and a light emitting device. The deep ultraviolet LED structure comprises a substrate, an n-type semiconductor layer arranged on one side of the substrate, a light emitting layer arranged on a side of the n-type semiconductor layer away from the substrate, a p-type semiconductor layer arranged on a side of the light emitting layer away from the substrate, a p-type electrode arranged on a side of the p-type semiconductor layer away from the substrate, and the material of the p-type electrode comprises at least one of n-Ga2O3 or n-(Al x Ga 1‑x )2O3, and x is 0-0.5; and an n-type electrode electrically connected with the n-type semiconductor layer. The deep ultraviolet LED structure has high ultraviolet transmittance, high stability, and can realize a top light emitting structure.

Description

Technical Field

[0001] This application belongs to the field of deep ultraviolet LED technology, specifically relating to deep ultraviolet LED structures, their fabrication methods, and light-emitting devices. Background Technology

[0002] Deep ultraviolet (DUV) light-emitting diodes (LEDs) in the wavelength range below 280 nm have become an ideal alternative to traditional mercury-containing toxic gas UV lamps due to their advantages such as small size, fast turn-on speed, environmental friendliness, low power consumption, long lifespan, and continuously tunable emission wavelength (200~365 nm). They have wide applications in sterilization, water purification, biochemical detection, medical diagnosis, aircraft early warning, and non-line-of-sight communication. However, the external quantum efficiency of commercially available DUV LEDs is currently less than 10%, far lower than that of mature InGaN-based blue LEDs, severely restricting their large-scale promotion in high-end applications. One bottleneck is that, due to the difficulty of p-type doping of AlGaN, traditional DUV LEDs typically use p-GaN as the hole injection layer. However, GaN and the ohmic electrodes deposited on top of it strongly absorb deep ultraviolet light, preventing photons from escaping from the p-side. Currently, deep ultraviolet (DUV) LEDs are typically packaged using flip-chip bonding, emitting light from the back of the substrate. Due to photon loss, total internal reflection, and other factors, DUV LEDs suffer from low photon extraction efficiency, severely degrading the device's light extraction efficiency and output power. Therefore, DUV LEDs still require further improvement. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a deep ultraviolet LED structure, its fabrication method, and a light-emitting device. This deep ultraviolet LED structure has high deep ultraviolet transmittance, high photon extraction efficiency, and can achieve top-emitting light.

[0004] A first aspect of this application provides a deep ultraviolet (DUV) LED structure. According to an embodiment of this application, the DUV LED structure includes: a substrate; an n-type semiconductor layer disposed on one side of the substrate; a light-emitting layer disposed on the side of the n-type semiconductor layer away from the substrate; a p-type semiconductor layer disposed on the side of the light-emitting layer away from the substrate; and a p-type electrode disposed on the side of the p-type semiconductor layer away from the substrate, wherein the p-type electrode is made of n-Ga₂O₃ or n-(Al₂O₃)₂O₃. x Ga 1-x At least one of n-Ga₂O₃ and x is 0 to 0.5; an n-type electrode, wherein the n-type electrode is electrically connected to the n-type semiconductor layer. This application utilizes ultrawide bandgap n-Ga₂O₃ and / or n-(Al₂O₃)₂O₃, which possess both high ultraviolet transmittance and high conductivity. x Ga 1-xUsing Ga₂O₃ as a transparent conductive electrode can significantly reduce the absorption of deep ultraviolet light, thus enabling the deep ultraviolet LED structure to exhibit high ultraviolet transmittance, high stability, and top-emitting structure. Ga₂O₃ possesses an ultra-wide bandgap of ~4.9 eV, with a corresponding absorption band edge at 253 nm, resulting in extremely high transmittance (>80%) in the deep ultraviolet region. Furthermore, doping can achieve a carrier concentration of 10... 15 ~10 20 cm -3 The n-type conductivity reduces the on-resistance of the device.

[0005] According to embodiments of this application, the p-type electrode includes a dopant element and satisfies at least one of the following conditions: The doping element includes at least one of Si, Ge, and Sn; The doping concentration of the dopant element is 0.03 wt% to 5 wt%.

[0006] According to an embodiment of this application, the thickness of the p-type electrode is 50 nm to 500 nm.

[0007] According to an embodiment of this application, the deep ultraviolet LED structure further includes: an interface control layer, the interface control layer being disposed between the p-type semiconductor layer and the p-type electrode, the interface control layer including at least one of a nitride layer and a metal nanoparticle layer, wherein the band gap of the nitride layer is smaller than the band gap of the p-type semiconductor layer and the band gap of the p-type electrode, preferably less than 3.5 eV; The work function of the metal nanoparticle layer is not less than 4.8 eV.

[0008] According to embodiments of this application, the deep ultraviolet LED structure satisfies at least one of the following conditions: The nitride layer includes at least one of InGaN and GaN; The thickness of the nitride layer is 0.5 nm to 10 nm; The metal nanoparticle layer includes at least one of Ni, Au, and Ir; The vacancy rate of the metal nanoparticles in the metal nanoparticle layer is 10%-70%; The particle size of the metal nanoparticles is 2 nm-800 nm.

[0009] According to embodiments of this application, the deep ultraviolet LED structure further includes at least one of the following: An aluminum nitride template layer is disposed between the substrate and the n-type semiconductor layer; A grid p-type ohmic electrode is disposed on the side of the p-type electrode away from the substrate.

[0010] According to embodiments of this application, the deep ultraviolet LED structure satisfies any one of the following conditions: The deep ultraviolet LED structure is a front-mounted structure, and the substrate includes at least one of sapphire, silicon, silicon carbide, and gallium oxide; The deep ultraviolet LED structure is a vertical structure, and the substrate includes at least one of silicon, silicon carbide, and gallium oxide.

[0011] A second aspect of this application provides a method for fabricating the aforementioned deep ultraviolet (DUV) LED structure. According to embodiments of this application, the method includes: growing an epitaxial structure on one side of a substrate using at least one of metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), magnetron sputtering, and pulsed laser deposition (PLD), wherein the epitaxial structure comprises an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer sequentially stacked on one side of the substrate, or the epitaxial structure comprises an aluminum nitride template layer, an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer sequentially stacked on one side of the substrate; depositing a p-type electrode on the side of the epitaxial structure away from the substrate using at least one of magnetron sputtering, PLD, and MOCVD; forming an n-type electrode electrically connected to the n-type semiconductor layer using electron beam evaporation; and annealing the product forming the n-type electrode in a protective atmosphere to obtain the DUV LED structure. This method is convenient and simple to operate, and the resulting DUV LED structure has high DUV transmittance and excellent overall performance.

[0012] According to embodiments of this application, the method further includes at least one of the following: After the epitaxial structure is formed and before the p-type electrode is formed, an interface control layer is formed on the side of the epitaxial structure away from the substrate using at least one of metal-organic chemical vapor deposition, magnetron sputtering, and electron beam evaporation. After the p-type electrode is formed, a grid of p-type ohmic electrodes is formed on the side of the p-type electrode away from the substrate by electron beam evaporation and / or magnetron sputtering.

[0013] A third aspect of this application provides a light-emitting device. According to an embodiment of this application, the light-emitting device includes the deep ultraviolet LED structure described above. This light-emitting device possesses all the features and advantages of the deep ultraviolet LED structure described above, which will not be repeated here.

[0014] This application uses an ultra-wide bandgap semiconductor material as the p-type electrode of a deep ultraviolet LED, replacing p-GaN and its upper metal electrode, to fabricate a deep ultraviolet LED structure that can achieve top-emitting light, which has at least the following beneficial effects: 1. High deep ultraviolet transmittance. Gallium oxide has an ultrawide bandgap of ~4.9 eV, exhibiting extremely high transmittance in the deep ultraviolet band above 250 nm. Using gallium oxide as the transparent conductive electrode in deep ultraviolet LEDs, replacing traditional p-GaN and metal electrodes (Ni / Au), significantly reduces the absorption of deep ultraviolet emitted photons, thereby improving the light extraction efficiency of the device.

[0015] 2. By constructing a tunnel junction of p-type electrode / interface control layer / p-type semiconductor layer through setting an interface control layer, the depletion region width on the p-type semiconductor side can be effectively reduced, the electron tunneling probability can be increased, and the hole injection efficiency can be increased. This can greatly improve photon extraction without sacrificing the electrical performance of the device, and is expected to revolutionize the existing DUV-LED chip design and packaging scheme.

[0016] 3. It can realize a top-emitting light structure, which not only simplifies the high-reflectivity electrode and dam structure and improves the device yield from the chip design and packaging level, but also can be integrated with silicon substrates to develop CMOS process compatible ultraviolet light-emitting chips and modules. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a deep ultraviolet LED structure according to an embodiment of this application.

[0018] Figure 2 This is a band structure diagram of a p-AlGaN / n-Ga2O3 heterojunction according to an embodiment of this application.

[0019] Figure 3 This is a schematic diagram of a deep ultraviolet LED structure according to another embodiment of this application.

[0020] Figure 4 This is a band structure diagram of a p-AlGaN / interface control layer / n-Ga2O3 tunnel junction according to an embodiment of this application.

[0021] Figure 5 This is a schematic diagram of a deep ultraviolet LED structure according to another embodiment of this application.

[0022] Figure 6 This is a schematic diagram of a deep ultraviolet LED structure according to another embodiment of this application.

[0023] Figure 7 This is a schematic diagram of a deep ultraviolet LED structure according to another embodiment of this application.

[0024] Figure 8 This is a transmittance data graph of the deep ultraviolet LED structure of Embodiment 1 and Comparative Example 1 of this application. Detailed Implementation

[0025] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0026] This application is based on the inventor's discoveries and understanding of the following facts and problems: As mentioned earlier, the strong absorption of deep ultraviolet light by GaN and ohmic electrodes prevents current deep ultraviolet LEDs from using a top-mounted structure, while a flip-chip structure results in low photon extraction efficiency, severely degrading the device's light extraction efficiency and output power. Meanwhile, compared to flip-chip structures, top-emitting top-mounted deep ultraviolet LED structures offer advantages such as simpler manufacturing processes and lower costs, and can also be integrated on mature semiconductor substrates like silicon or SiC. Therefore, developing a transparent conductive electrode with high transmittance in the deep ultraviolet band to meet the application requirements of high-efficiency, top-emitting deep ultraviolet LEDs would be of great significance. Researchers have proposed various improvement schemes, such as using ITO as a transparent conductive electrode with micropores, using ITO and AZO layers as the transparent conductive layer of the UV chip, and using metal-doped ITO as a transparent conductive film. Other researchers have proposed removing a portion of p-GaN to reduce its absorption of DUV light; and replacing p-GaN with a composite transparent conductive layer consisting of a wide-bandgap semiconductor superlattice ohmic contact layer, a metal oxide work function adjustment layer, and a graphene layer or a Ga2O3 wide-bandgap transparent electrode layer to reduce the absorption of emitted photons. However, these technologies are not suitable for top-emitting deep UV LEDs, as the metal p-electrode on top of the transparent conductive layer will severely absorb deep UV light, failing to meet the structural requirements of top-emitting deep UV LEDs.

[0027] In response to the above situation, the inventors of this application conducted in-depth research and proposed using Ga2O3 and / or (Al2O3) ultrawide bandgap semiconductor materials that combine high deep ultraviolet transmittance and high conductivity. x Ga 1-x As a p-type electrode, 2O3 can not only improve light extraction efficiency, but also reduce the potential barrier through band modulation at the interface between the p-type electrode and the p-type semiconductor layer, thereby reducing the device turn-on voltage and thus obtaining a high-efficiency deep ultraviolet LED structure.

[0028] In view of this, a first aspect of this application provides a deep ultraviolet LED structure. According to an embodiment of this application, referring to... Figure 1The deep ultraviolet LED structure includes: a substrate 1; an n-type semiconductor layer 3 disposed on one side of the substrate 1; a light-emitting layer 4 disposed on the side of the n-type semiconductor layer 3 away from the substrate 1; a p-type semiconductor layer 5 disposed on the side of the light-emitting layer 4 away from the substrate 1; and a p-type electrode 7 disposed on the side of the p-type semiconductor layer 5 away from the substrate 1, wherein the material of the p-type electrode 7 includes n-Ga2O3 or n-(Al2O3)2O3. x Ga 1-x At least one of 2O3, x is 0~0.5; n-type electrode 8, the n-type electrode 8 being electrically connected to the n-type semiconductor layer 3.

[0029] This application utilizes n-Ga2O3 and / or n-(Al) with an ultrawide bandgap that combines high ultraviolet transmittance and high conductivity. x Ga 1-x Using Ga₂O₃ as a transparent conductive electrode can significantly reduce the absorption of deep ultraviolet light, thus enabling the deep ultraviolet LED structure to exhibit high ultraviolet transmittance, high stability, and top-emitting structure. Ga₂O₃ possesses an ultra-wide bandgap of ~4.9 eV, with a corresponding absorption band edge at 253 nm, resulting in extremely high transmittance (>80%) in the deep ultraviolet region. Furthermore, doping can achieve a carrier concentration of 10... 15 ~10 20 cm -3 The n-type conductivity reduces the on-resistance of the device.

[0030] According to embodiments of this application, the p-type electrode includes a dopant element. In some embodiments, the dopant element includes at least one of Si, Ge, and Sn. By doping with the above elements, the p-type electrode can achieve n-type conductivity, thereby reducing the on-resistance of the device. In some embodiments, the doping concentration of the dopant element is 0.03wt% to 5wt%, specifically 0.03wt%, 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, or any range between two of these. Within the above doping range, the p-type electrode exhibits high conductivity, which is beneficial for improving the overall performance of the device.

[0031] According to embodiments of this application, the thickness of the p-type electrode is 50 nm to 500 nm, specifically within the range of 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, or any two of these ranges. Within this thickness range, it exhibits both good conductivity and low deep ultraviolet absorption.

[0032] According to embodiments of this application, research has found that Al 0.4 Ga 0.6 The conduction band shift and valence band shift of the N / Ga2O3 heterojunction are 0.18 and 0.35 eV, respectively, and its band arrangement belongs to type-II interleaved type (He X, Sun R, Xu X, et al. ACS Applied Materials & Interfaces, 2024, 16: 64146-64155). n-Ga2O3 or n-(Al) x Ga 1-x Using at least one of p-type GaN and n-Ga2O3 as a p-type electrode, the high electron concentration within it may widen the depletion region at the p-type semiconductor layer / p-type electrode heterojunction interface, thereby reducing the hole injection efficiency of the p-type semiconductor layer and leading to increased resistance. Taking p-AlGaN as the p-type semiconductor layer material and n-Ga2O3 as the p-type electrode material as an example, the energy band diagram of the p-AlGaN / n-Ga2O3 heterojunction is as follows. Figure 2 As shown ( Figure 2 In this context, Ec represents the conduction band, Ef represents the Fermi level, and Ev represents the valence band. Therefore, this application constructs a tunnel junction by adding an interface modulation layer between the p-type semiconductor layer and the p-type electrode to modulate the energy band. This reduces the width of the depletion region on the p-type semiconductor layer side and improves hole injection efficiency.

[0033] Therefore, according to the embodiments of this application, referring to Figure 3 The deep ultraviolet LED structure further includes an interface modulation layer 6, which is disposed between the p-type semiconductor layer 5 and the p-type electrode 7. The interface modulation layer 6 includes at least one of a nitride layer and a metal nanoparticle layer. The band gap of the interface modulation layer is smaller than the band gap of the p-type semiconductor layer and the band gap of the p-type electrode. In some embodiments, the band gap of the nitride layer is less than 3.5 eV. In some embodiments, the work function of the metal nanoparticle layer is not less than 4.8 eV. By setting the interface modulation layer for bandgap modulation, the depletion region width on the p-type semiconductor layer side can be effectively reduced, improving hole injection efficiency.

[0034] Specifically, when a forward bias is applied to the deep ultraviolet LED structure, the tunnel junction formed by the p-type electrode / interface control layer / p-type semiconductor layer at the top is under a reverse bias. The high polarization electric field generated by the high polarization charge density at the interface causes the energy band of the interface control layer to bend, aligning the energy bands on both sides of the p-type electrode-p-type semiconductor layer. Valence band electrons of the p-type semiconductor layer cross the potential barrier and are injected into the conduction band of the p-type electrode through quantum tunneling. The resulting holes are simultaneously injected into the active region and undergo radiative recombination with electrons. This structure can effectively reduce the depletion region width of the p-type semiconductor layer, increase electron tunneling, and improve hole injection efficiency. Taking p-AlGaN as the p-type semiconductor layer material and n-Ga2O3 as the p-type electrode material as an example, the energy band diagram of the p-AlGaN / interface control layer / n-Ga2O3 tunnel junction is as follows. Figure 4 As shown ( Figure 4 In this context, Ec is the conduction band, Ef is the Fermi level, and Ev is the valence band.

[0035] According to embodiments of this application, the nitride layer includes at least one of InGaN and GaN. This results in a narrower bandgap, which is more conducive to effectively reducing the depletion region width of the p-type semiconductor layer, increasing electron tunneling, and improving hole injection efficiency.

[0036] According to embodiments of this application, the thickness of the nitride layer is 0.5 nm to 10 nm, specifically within the range of 0.5 nm, 1 nm, 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, or any two of these ranges. This thickness range effectively reduces the depletion region width of the p-type semiconductor layer, increases the electron tunneling probability, and improves hole injection efficiency, while having minimal impact on the deep ultraviolet transmittance of the deep ultraviolet LED structure.

[0037] According to embodiments of this application, the metal nanoparticle layer includes at least one of Ni, Au, and Ir. This facilitates a more effective reduction in the depletion region width of the p-type semiconductor layer, increases electron tunneling, and improves hole injection efficiency.

[0038] According to embodiments of this application, the duty cycle of the metal nanoparticles in the metal nanoparticle layer is between 10% and 70%, specifically within the ranges of 10%, 20%, 30%, 40%, 50%, 60%, 70%, or any two thereof. This duty cycle range minimizes the absorption of emitted photons while significantly improving the charge transport performance at the interface.

[0039] According to embodiments of this application, the particle size of the metal nanoparticles is 2 nm to 800 nm, specifically within the range of 2 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, or any two of these ranges. This size range minimizes the absorption of emitted photons while actively modulating the carrier transport mechanism.

[0040] According to the embodiments of this application, referring to Figure 5 The deep ultraviolet LED structure further includes an aluminum nitride template layer 2, which is disposed between the substrate 1 and the n-type semiconductor layer 2. The aluminum nitride template layer improves the quality of the n-type semiconductor layer, thereby enhancing the performance of the deep ultraviolet LED structure.

[0041] According to the embodiments of this application, referring to Figure 6 The deep ultraviolet LED structure also includes a grid-type p-electrode 9, which is disposed on the side of the p-electrode 7 away from the substrate 1. This improves conductivity, enhances ohmic contact, and increases transmittance.

[0042] According to embodiments of this application, the grid p-type ohmic electrode adopts a grid structure, with a light-transmitting portion ratio >50%. Therefore, it possesses both high conductivity and high transmittance.

[0043] According to embodiments of this application, the work function of the grid p-type ohmic electrode is >4.0 eV, and the metal thickness is 20 nm to 400 nm. This further improves the ohmic contact characteristics of the metal-semiconductor material.

[0044] According to embodiments of this application, the material of the grid p-type ohmic electrode includes metal, specifically at least one selected from Ti, Al, Ni, and Au. In some embodiments, the grid p-type ohmic electrode can be a Ti / Al / Ni / Au electrode with thicknesses of 30 nm / 120 nm / 30 nm / 50 nm, respectively. In other embodiments, the grid p-type ohmic electrode can be a Ti / Au electrode with thicknesses of 50 nm / 50 nm, respectively.

[0045] It is understood that the deep ultraviolet LED structure of this application can achieve top light emission by using a material with high deep ultraviolet transmittance as a p-type electrode. Specifically, it can be a front-mounted structure or a vertical structure, thus having the advantages of simple manufacturing process and low cost. At the same time, it can also be integrated on silicon or SiC substrates with mature semiconductor technology.

[0046] According to the embodiments of this application, referring to Figure 6The deep ultraviolet LED structure is a front-mounted structure, and the substrate includes at least one of sapphire, silicon, silicon carbide, and gallium oxide. Therefore, the manufacturing process is simple, the cost is low, and a wider range of substrate types can be used.

[0047] According to the embodiments of this application, referring to Figure 7 The deep ultraviolet LED structure is a vertical structure, and the substrate includes at least one of silicon, silicon carbide, and gallium oxide. Therefore, the manufacturing process is simple, the cost is low, and a wider range of substrate types can be used.

[0048] According to embodiments of this application, in the deep ultraviolet LED structure, the n-type semiconductor material may include n-AlGaN; the light-emitting layer material may include AlGaN multiple quantum wells; the p-type semiconductor material may include p-AlGaN; and the n-type electrode material may include metal, specifically at least one of Ti, Al, Ni, and Au. Therefore, the deep ultraviolet LED structure exhibits superior overall performance.

[0049] A second aspect of this application provides a method for fabricating the aforementioned deep ultraviolet LED structure. According to embodiments of this application, the method includes the following steps: S10: An epitaxial structure is grown on one side of a substrate using at least one of metal-organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE), wherein the epitaxial structure comprises an n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer sequentially stacked on one side of the substrate, or the epitaxial structure comprises an aluminum nitride template layer, an n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer sequentially stacked on one side of the substrate.

[0050] According to the embodiments of this application, the substrate, aluminum nitride template layer, n-type semiconductor layer, light-emitting layer and p-type semiconductor layer can be the same as those described above, and will not be repeated here.

[0051] According to the embodiments of this application, the parameters of the specific operating steps of metal-organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) are not particularly limited and can be flexibly selected and adjusted according to actual needs.

[0052] In some embodiments, the deep ultraviolet LED epitaxial structure is grown based on metal-organic chemical vapor deposition (MOCVD), with the metal source being one or more of trimethylaluminum, triethylaluminum, trimethylgallium, and triethylgallium, the gas pressure being 20 torr to 2000 torr, and the epitaxial temperature being 900℃ to 1300℃.

[0053] S20: Deposit a p-type electrode on the side of the epitaxial structure away from the substrate using at least one of magnetron sputtering, pulsed laser deposition (PLD), and metal-organic chemical vapor deposition.

[0054] In some embodiments, n-type doped Ga2O3 can be prepared as a p-type electrode using laser pulse deposition, with a substrate temperature of 700℃~850℃, a target spacing of 40mm~50mm, an oxygen pressure of 20mTorr, a laser energy of 100mJ~130mJ, a pulse laser frequency of 2Hz~5Hz, and a growth time of 10min~120min.

[0055] S30: An n-type electrode electrically connected to the n-type semiconductor layer is formed using an electron beam evaporation method.

[0056] In some embodiments, when the deep ultraviolet structure is a front-mounted structure, inductively coupled plasma etching of the deep ultraviolet LED epitaxial layer can be used to form a mesa that extends to the n-type semiconductor layer (i.e., is only exposed but does not penetrate the n-type semiconductor layer). Then, an n-type electrode electrically connected to the n-type semiconductor layer can be formed on the mesa by electron beam evaporation.

[0057] In some embodiments, Ar / Cl2 / BCl3 plasma etching of the deep ultraviolet LED epitaxial layer can be used, with Ar / Cl2 / BCl3 fluxes of 20 / 20 / 30 sccm, and the mesa area can be 100×500 µm. 2 .

[0058] In some embodiments, when the deep ultraviolet structure is a vertical structure, the n-type electrode can be directly formed on the side of the substrate away from the light-emitting layer. As an example, an n-type electrode can be deposited on the back side of the substrate using electron beam evaporation. Specifically, the n-type electrode can be a Ti / Al / Ni / Au metal ohmic electrode.

[0059] S40: Anneal the product forming the n-type electrode in a protective atmosphere to obtain the deep ultraviolet LED structure.

[0060] According to embodiments of this application, the protective atmosphere can be at least one of N2, Ar, and air. This effectively protects the device while reducing cost.

[0061] According to embodiments of this application, the annealing temperature can be 400℃~900℃, specifically 400℃, 500℃, 600℃, 700℃, 800℃, 900℃ or any two of them.

[0062] According to an embodiment of this application, the above method further includes: after forming the epitaxial structure and before forming the p-type electrode, forming an interface control layer on the side of the epitaxial structure away from the substrate using at least one of metal-organic chemical vapor deposition, magnetron sputtering, and electron beam evaporation.

[0063] In some embodiments, when the interface control layer is made of metal nanoparticles, thermal annealing can be performed after the deposition of the ultrathin metal layer to form metal nanoparticles. The annealing temperature can be 400°C to 900°C, specifically 400°C, 500°C, 600°C, 700°C, 800°C, 900°C or any two of them. The annealing atmosphere includes N2, Ar, air or a mixture of several of them.

[0064] According to an embodiment of this application, the above method further includes: after forming the p-type electrode, forming a grid p-type ohmic electrode on the side of the p-type electrode away from the substrate by electron beam evaporation and / or magnetron sputtering.

[0065] In some embodiments, the work function of the grid p-type ohmic electrode is >4.0 eV, and the metal thickness is between 20 nm and 400 nm, which can be an alloy or a multilayer structure. Furthermore, the metal electrode adopts a grid structure, and the proportion of the light-transmitting portion is >50%.

[0066] In a third aspect, this application provides a light-emitting device. According to an embodiment of this application, the light-emitting device includes the deep ultraviolet LED structure described above. This light-emitting device can be used in fields such as sterilization and disinfection, water purification, biochemical detection, medical diagnosis, aircraft early warning, and non-line-of-sight communication.

[0067] The embodiments of this application are described in detail below.

[0068] Example 1: A deep ultraviolet LED epitaxial structure was grown on a sapphire substrate (1) using metal-organic chemical vapor deposition (MOCVD). The epitaxial structure included an AlN template layer (2), n-AlGaN (3), a quantum well light-emitting layer (4), and p-AlGaN (5). The emission wavelength was 275 nm, and the hole concentration of Mg-doped AlGaN was 5 × 10⁻⁶. 17 cm -3 .

[0069] A 5 nm p-GaN interface control layer was epitaxially formed on p-AlGaN using MOCVD (6).

[0070] Si-doped conductive gallium oxide (7) was deposited on the interface control layer (6) using pulsed laser deposition (PLD) technology. The ratio of SiO2 / (SiO2+Ga2O3) in the target material was 0.03 wt%, the substrate temperature was 750 ℃, the chamber pressure was 20 mTorr, and the thickness was 200 nm.

[0071] Following photolithography, inductively coupled plasma (ICP-PAP) etching was used to etch the deep ultraviolet LED epitaxial layer, forming mesa extending to the Si-doped n-AlGaN layer (i.e., only exposed but not penetrating the Si-doped n-AlGaN layer 3). Ar / Cl2 / BCl3 plasmas were used with flow rates of 20 / 20 / 30 sccm, and the mesa area was 100 × 500 µm. 2 .

[0072] Based on photolithography, overlays were made on the existing thin film surface, and Ti / Al / Ni / Au electrodes were deposited on the exposed n-AlGaN layer by electron beam evaporation (8), with thicknesses of 30 / 120 / 30 / 50 nm, respectively.

[0073] After removing the photoresist, the sample was annealed in a rapid annealing furnace at 700℃ for 1 min under a nitrogen atmosphere. The resulting deep ultraviolet LED structure is referenced. Figure 5 .

[0074] Example 2: A deep ultraviolet LED epitaxial structure was grown on a sapphire substrate (1) using metal-organic chemical vapor deposition (MOCVD). The epitaxial structure included an AlN template layer (2), n-AlGaN (3), a quantum well light-emitting layer (4), and p-AlGaN (5). The emission wavelength was 275 nm, and the hole concentration of Mg-doped AlGaN was 5 × 10⁻⁶. 17 cm -3 .

[0075] A 5 nm InGaN interface control layer was epitaxially formed on p-AlGaN using MOCVD (6).

[0076] Si-doped conductive gallium oxide thin films were deposited on deep ultraviolet LED epitaxial structures using pulsed laser deposition (PLD) technology (7). The ratio of SiO2 / (SiO2+Ga2O3) in the target material was 0.03 wt%, the substrate temperature was 750 ℃, the chamber pressure was 20 mTorr, and the thickness was 200 nm.

[0077] Following photolithography, inductively coupled plasma (ICP-PAP) etching was used to etch the deep ultraviolet LED epitaxial layer, forming mesa extending to the Si-doped n-AlGaN layer (i.e., only exposed but not penetrating the Si-doped n-AlGaN layer 3). Ar / Cl2 / BCl3 plasmas were used with flow rates of 20 / 20 / 30 sccm, and the mesa area was 100 × 500 µm. 2 .

[0078] Based on photolithography, overlays were made on the existing thin film surface, and Ti / Al / Ni / Au electrodes were deposited on the exposed n-AlGaN layer by electron beam evaporation (8), with thicknesses of 30 / 120 / 30 / 50 nm, respectively.

[0079] After removing the photoresist, the sample was annealed in a rapid annealing furnace at a nitrogen atmosphere of 700°C for 1 min.

[0080] Based on photolithography, overlays were made on the existing thin film surface, and a grid of p-type ohmic electrodes Ti / Au (9) was deposited on the n-Ga2O3 layer by electron beam evaporation with thicknesses of 50 / 50 nm.

[0081] After removing the photoresist, the sample was annealed in a rapid annealing furnace at 470℃ for 1 min under a nitrogen atmosphere. The resulting deep ultraviolet LED structure is referenced. Figure 6 .

[0082] Example 3: Deep ultraviolet LED epitaxial structures were grown on conductive SiC substrates (1) using MOCVD. The epitaxial structure included n-AlGaN (3), a quantum well light-emitting layer (4), and p-AlGaN (5). The emission wavelength was 275 nm, and the hole concentration of Mg-doped AlGaN was 5 × 10⁻⁶. 17 cm -3 .

[0083] 2 nm of metallic nickel was deposited on p-AlGaN by electron beam evaporation, and nickel cluster particles were formed by rapid annealing furnace as an interface control layer (6).

[0084] Conductive n-Ga2O3 thin films were grown on a deep ultraviolet full structure with Ni metal cluster particles using pulsed laser deposition equipment (7), with Si, Ge, Sn and other group IV elements as dopants, and the thickness was about 200 nm.

[0085] Mesh p-type ohmic electrodes Ti / Au (9) were deposited on an n-Ga2O3 layer by electron beam evaporation with thicknesses of 50 / 50 nm.

[0086] The samples were annealed in a rapid annealing furnace under a nitrogen atmosphere at a temperature of 470 °C for 1 min.

[0087] A top-emitting vertical deep ultraviolet LED was fabricated by depositing a metal ohmic electrode (8) on the back side of a double-sided polished conductive SiC substrate using electron beam evaporation. The resulting deep ultraviolet LED structure is shown in the figure. Figure 7 .

[0088] Comparative Example 1 Same as Example 1, except that: 200 nm p-GaN is directly prepared on p-AlGaN (5) as a transparent conductive layer using metal-organic chemical vapor deposition (replacing the structure of "5 nm p-GaN interface control layer (6) + 200 nm Si-doped conductive gallium oxide (7)" in Example 1), and then photolithography, inductively coupled plasma etching of the deep ultraviolet LED epitaxial layer, and subsequent steps are performed in sequence, with the remaining parameters being the same as in Example 1.

[0089] Performance testing: Ultraviolet transmittance: In Example 1, after the step of depositing Si-doped conductive gallium oxide on p-AlGaN (5) was completed, the ultraviolet transmittance of the sample after depositing Si-doped conductive gallium oxide was tested directly before photolithography; in Comparative Example 1, after the preparation of the p-GaN transparent conductive layer was completed, the ultraviolet transmittance of the sample was tested under the same test conditions before photolithography. Specifically, an ultraviolet-visible spectrophotometer was used, with a sapphire substrate as the reference, to test the transmittance of the comparative example sample and the example sample respectively, with a test range of 200nm-800nm ​​and a step size of 1.0nm.

[0090] Transmittance data chart Figure 8 In the diagram, the black curve represents a conventional device (i.e., Comparative Example 1), which uses p-GaN as a transparent conductive layer and has almost zero transmittance in the deep ultraviolet 280 nm range. The red curve represents the technical solution of this application (Example 1), which uses n-Ga2O3 as a transparent conductive layer and has significantly higher transmittance in the deep ultraviolet band than the conventional device, with a transmittance of approximately 89% at 280 nm. Compared with the conventional device, the technical solution of this application can effectively reduce the absorption of emitted photons and improve the light extraction efficiency at the top of the device.

[0091] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0092] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A deep ultraviolet LED structure, characterized in that, include: Substrate; An n-type semiconductor layer is disposed on one side of the substrate; A light-emitting layer is disposed on the side of the n-type semiconductor layer away from the substrate; A p-type semiconductor layer is disposed on the side of the light-emitting layer away from the substrate; A p-type electrode is disposed on the side of the p-type semiconductor layer away from the substrate, and the material of the p-type electrode includes n-Ga₂O₃ or n-(Al₂O₃)₂O₃. x Ga 1-x At least one of )2O3, where x is 0~0.5; The n-type electrode is electrically connected to the n-type semiconductor layer.

2. The deep ultraviolet LED structure according to claim 1, characterized in that, The p-type electrode includes a doping element and satisfies at least one of the following conditions: The doping element includes at least one of Si, Ge, and Sn; The doping concentration of the dopant element is 0.03 wt% to 5 wt%.

3. The deep ultraviolet LED structure according to claim 1, characterized in that, The thickness of the p-type electrode is 50 nm to 500 nm.

4. The deep ultraviolet LED structure according to claim 1, characterized in that, Also includes: An interface control layer is disposed between the p-type semiconductor layer and the p-type electrode. The interface control layer includes at least one of a nitride layer and a metal nanoparticle layer. The band gap of the nitride layer is smaller than the band gap of the p-type semiconductor layer and the band gap of the p-type electrode, preferably less than 3.5 eV; The work function of the metal nanoparticle layer is not less than 4.8 eV.

5. The deep ultraviolet LED structure according to claim 4, characterized in that, At least one of the following conditions must be met: The nitride layer includes at least one of InGaN and GaN; The thickness of the nitride layer is 0.5 nm to 10 nm; The metal nanoparticle layer includes at least one of Ni, Au, and Ir; The vacancy rate of the metal nanoparticles in the metal nanoparticle layer is 10%-70%; The particle size of the metal nanoparticles is 2 nm-800 nm.

6. The deep ultraviolet LED structure according to claim 1, characterized in that, It also includes at least one of the following: An aluminum nitride template layer is disposed between the substrate and the n-type semiconductor layer; A grid p-type ohmic electrode is disposed on the side of the p-type electrode away from the substrate.

7. The deep ultraviolet LED structure according to claim 1, characterized in that, If any of the following conditions are met: The deep ultraviolet LED structure is a front-mounted structure, and the substrate includes at least one of sapphire, silicon, silicon carbide, and gallium oxide; The deep ultraviolet LED structure is a vertical structure, and the substrate includes at least one of silicon, silicon carbide, and gallium oxide.

8. A method for preparing a deep ultraviolet LED structure according to any one of claims 1 to 7, characterized in that, include: An epitaxial structure is grown on one side of a substrate using at least one of metal-organic chemical vapor deposition, molecular beam epitaxy, magnetron sputtering, and pulsed laser deposition. The epitaxial structure includes an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer sequentially stacked on one side of the substrate, or the epitaxial structure includes an aluminum nitride template layer, an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer sequentially stacked on one side of the substrate. A p-type electrode is deposited on the side of the epitaxial structure away from the substrate using at least one of magnetron sputtering, pulsed laser deposition, and metal-organic chemical vapor deposition; An n-type electrode electrically connected to the n-type semiconductor layer is formed using an electron beam evaporation method; The product forming the n-type electrode is annealed in a protective atmosphere to obtain the deep ultraviolet LED structure.

9. The method according to claim 8, characterized in that, It also includes at least one of the following: After the epitaxial structure is formed and before the p-type electrode is formed, an interface control layer is formed on the side of the epitaxial structure away from the substrate using at least one of metal-organic chemical vapor deposition, magnetron sputtering, and electron beam evaporation. After the p-type electrode is formed, a grid of p-type ohmic electrodes is formed on the side of the p-type electrode away from the substrate by electron beam evaporation and / or magnetron sputtering.

10. A light-emitting device, characterized in that, The deep ultraviolet LED structure includes any one of claims 1 to 7.

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