Ultraviolet LED and manufacturing method thereof

Abstract

The present application provides a UV LED and a method for manufacturing the same. In the manufacturing method, an N-type transition layer is formed on an electron-supplying layer and / or a P-type transition layer is formed on a hole-supplying layer. The materials of both the electron-supplying layer and the hole-supplying layer include at least Al, Ga, and N, and the materials of the N-type transition layer and the P-type transition layer are GaN. An N-electrode is formed on the N-type transition layer, and an ohmic contact is formed between the N-type transition layer and the N-electrode. A P-electrode is formed on the P-type transition layer, and an ohmic contact is formed between the P-type transition layer and the P-electrode. Compared to directly forming an ohmic contact electrode on an aluminum-containing GaN-based material, this method avoids annealing, and avoids degradation of the electron-supplying layer's performance due to high temperatures during the annealing process, thereby reducing the electron-hole recombination rate in the active layer.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to an ultraviolet LED and a method for manufacturing the same. Background Art

[0002] Ultraviolet (UV) light is categorized as UVC (ultraviolet light with a wavelength less than 280nm), UVB (ultraviolet light with a wavelength between 280nm and 315nm), and UVA (ultraviolet light between 315nm and 400nm). UVA is primarily used for UV curing and document and banknote authentication; UVB is primarily used in medical treatment, printing, and aesthetic applications such as air purifiers using photocatalysts; and UVC is primarily used for sterilization, biochemical testing, high-density information storage, and military confidential communications. UV LEDs offer advantages such as energy efficiency, environmental friendliness, lightweight design, spectral purity, safety, and the absence of mercury pollution, making them suitable replacements for traditional mercury-containing UV light sources. x Ga 1-x The emission wavelength of the ultraviolet LED with N (0≤x≤1) material as the active region covers the ultraviolet band of 210nm to 365nm (called short-wave ultraviolet), and is an ideal material for realizing ultraviolet LED device products in this band.

[0003] Existing Al x Ga 1-x The luminous efficiency of N-based ultraviolet LEDs with wavelengths below 280nm is not high. Summary of the Invention

[0004] The object of the present invention is to provide an ultraviolet LED and a manufacturing method thereof to improve luminous efficiency.

[0005] To achieve the above object, one aspect of the present invention provides a UV LED, comprising:

[0006] An electron supply layer, a hole supply layer, and an active layer between the electron supply layer and the hole supply layer, wherein the materials of the electron supply layer and the hole supply layer both include at least three elements: Al, Ga, and N; an N-type transition layer is provided on the electron supply layer and / or a P-type transition layer is provided on the hole supply layer, and the materials of the N-type transition layer and the P-type transition layer are GaN; an N-electrode is provided on the N-type transition layer, and an ohmic contact is formed between the N-type transition layer and the N-electrode; a P-electrode is provided on the P-type transition layer, and an ohmic contact is formed between the P-type transition layer and the P-electrode.

[0007] Optionally, when the electron supply layer has the N-type transition layer on it, an N-type graded material layer is provided between the electron supply layer and the N-type transition layer, the N-type graded material layer comprises at least three elements: Al, Ga, and N, and the mass percentage of Ga in the N-type graded material layer is greater than the mass percentage of Ga in the electron supply layer;

[0008] When the P-type transition layer is provided on the hole-supplying layer, a P-type gradient material layer is provided between the hole-supplying layer and the P-type transition layer, and the P-type gradient material layer includes at least three elements: Al, Ga, and N. The mass percentage of Ga in the P-type gradient material layer is greater than the mass percentage of Ga in the hole-supplying layer.

[0009] Optionally, the N-type transition layer is an N-type ion heavily doped GaN layer, and / or the P-type transition layer is a P-type ion heavily doped GaN layer.

[0010] Optionally, the electron supply layer and / or the hole supply layer is made of AlGaN.

[0011] Optionally, the active layer includes a quantum well structure.

[0012] Optionally, the quantum well structure is a multi-quantum well structure.

[0013] Optionally, the quantum well structure includes Al x Ga 1-x N layer and Al y Ga 1-y N layers, 1≥x≥0, 1≥y≥0.

[0014] Optionally, an electron blocking layer is provided between the hole-supplying layer and the active layer.

[0015] Optionally, the material of the N-electrode and / or the P-electrode is at least one of Ti, Al, Ni, and Au.

[0016] Optionally, a mask layer is provided on the electron supply layer and the hole supply layer, the mask layer is made of insulating material, and a region of the mask layer is complementary to a region of the N-type transition layer and the P-type transition layer.

[0017] A second aspect of the present invention provides a method for manufacturing an ultraviolet LED, comprising:

[0018] Providing a first functional layer, wherein the first functional layer is one of an electron supply layer and a hole supply layer, and a material of the first functional layer includes at least three elements: Al, Ga, and N;

[0019] forming an active layer on the first functional layer;

[0020] forming a second functional layer on the active layer, the second functional layer being the other of the electron supply layer and the hole supply layer, wherein the material of the second functional layer comprises at least three elements: Al, Ga, and N;

[0021] Patterning the second functional layer and the active layer, exposing a portion of the first functional layer, and forming a transition layer on the second functional layer and / or the exposed first functional layer, wherein the transition layer on the electron supply layer is an N-type transition layer, the transition layer on the hole supply layer is a P-type transition layer, and the material of the N-type transition layer and the P-type transition layer is GaN;

[0022] An N-electrode is formed on the N-type transition layer, and an ohmic contact is formed between the N-type transition layer and the N-electrode; a P-electrode is formed on the P-type transition layer, and an ohmic contact is formed between the P-type transition layer and the P-electrode.

[0023] Optionally, before forming the N-type transition layer on the electron supply layer, an N-type graded material layer is first formed, wherein the N-type graded material layer includes at least three elements: Al, Ga, and N, and the mass percentage of Ga in the N-type graded material layer is greater than the mass percentage of Ga in the electron supply layer;

[0024] And / or before forming the P-type transition layer on the hole-supplying layer, a P-type gradient material layer is first formed, wherein the P-type gradient material layer includes at least three elements: Al, Ga, and N, and the mass percentage of Ga in the P-type gradient material layer is greater than the mass percentage of Ga in the hole-supplying layer.

[0025] Optionally, the N-type transition layer is an N-type ion heavily doped GaN layer, and / or the P-type transition layer is a P-type ion heavily doped GaN layer.

[0026] Optionally, before forming a transition layer on the second functional layer and / or the exposed first functional layer, a mask layer is formed on the second functional layer and the exposed first functional layer, the mask layer is an insulating material, and the area of ​​the mask layer is complementary to the area of ​​the transition layer to be formed.

[0027] Optionally, the electron supply layer and / or the hole supply layer is made of AlGaN.

[0028] Optionally, the active layer includes a quantum well structure.

[0029] Optionally, the quantum well structure is a multi-quantum well structure.

[0030] Optionally, the quantum well structure includes Al x Ga 1-x N layer and Al y Ga1-y N layers, 1≥x≥0, 1≥y≥0.

[0031] Optionally, an electron blocking layer is provided between the hole-supplying layer and the active layer.

[0032] Optionally, the material of the N-electrode and / or the P-electrode is at least one of Ti, Al, Ni, and Au.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] In the method for manufacturing a UV LED of the present invention, an N-type transition layer is formed on the electron supply layer and / or a P-type transition layer is formed on the hole supply layer. The materials of both the electron supply layer and the hole supply layer include at least Al, Ga, and N, and the materials of the N-type transition layer and the P-type transition layer are GaN. An N-electrode is formed on the N-type transition layer, and an ohmic contact is formed between the N-type transition layer and the N-electrode. A P-electrode is formed on the P-type transition layer, and an ohmic contact is formed between the P-type transition layer and the P-electrode. Compared to directly forming an ohmic contact electrode on an aluminum-containing GaN-based material, this method avoids annealing, and avoids the degradation of the electron supply layer performance caused by the high temperature during the annealing process, thereby reducing the electron-hole recombination rate in the active layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a flow chart of a method for manufacturing an ultraviolet LED according to a first embodiment of the present invention;

[0036] Figures 2 to 6 yes Figure 1 Schematic diagram of the intermediate structure corresponding to the process;

[0037] Figure 7 is in accordance with Figure 1 Schematic diagram of the cross-sectional structure of the UV LED produced by the process;

[0038] Figure 8 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a second embodiment of the present invention;

[0039] Figure 9 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a third embodiment of the present invention;

[0040] Figure 10 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a fourth embodiment of the present invention;

[0041] Figure 11 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a fifth embodiment of the present invention;

[0042] Figure 12 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a sixth embodiment of the present invention;

[0043] Figure 13 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a seventh embodiment of the present invention;

[0044] Figure 14 is a schematic cross-sectional structural diagram of an ultraviolet LED according to an eighth embodiment of the present invention;

[0045] Figure 15 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a ninth embodiment of the present invention;

[0046] Figure 16 FIG. 1 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a tenth embodiment of the present invention.

[0047] To facilitate understanding of the present invention, all reference numerals appearing in the present invention are listed below:

[0048] Substrate 100 Electron supply layer 11

[0049] Active layer 12 Hole supply layer 13

[0050] N-type transition layer 141 P-type transition layer 142

[0051] N electrode 151 P electrode 152

[0052] N-type graded material layer 161 P-type graded material layer 162

[0053] N-type ion heavily doped GaN layer 141 ′ electron blocking layer 17

[0054] P-type ion heavily doped GaN layer 142' mask layer 18

[0055] UV LED1, 2, 3, 4, 5, 6, 7, 8, 9, 10 DETAILED DESCRIPTION

[0056] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0057] Figure 1 4 is a flow chart of a method for manufacturing an ultraviolet LED according to a first embodiment of the present invention. Figures 2 to 6 yes Figure 1 Schematic diagram of the intermediate structure corresponding to the process. Figure 7 is in accordance with Figure 1 Schematic diagram of the cross-sectional structure of the UV LED produced by the process.

[0058] First, refer to Figure 1 Step S1, Figure 2 and Figure 3As shown, a first functional layer is provided, which is an electron supply layer 11. The material of the electron supply layer 11 includes at least three elements: Al, Ga, and N. Figure 3 It is along Figure 2 Cross-sectional view along line AA.

[0059] The electron supply layer 11 may be an N-type semiconductor, such as an N-type III-V compound. The N-type doping element may include at least one of Si, Ge, Sn, Se, or Te. In some embodiments, the material of the electron supply layer 11 includes AlGaN, that is, only includes Al, Ga, and N. More specifically, the ratio of Al, Ga, and N is not limited, that is, the material is Al m Ga 1-m N, where m is the percentage of the mass of Al to the sum of the masses of Al and Ga, 1>m>0. In some embodiments, the material of the electron supply layer 11 may include In, P, and other elements in addition to Al, Ga, and N.

[0060] The electron-supplying layer 11 may include one or more layers.

[0061] Next, refer to Figure 1 Step S2 in Figure 2 and Figure 3 As shown, an active layer 12 is formed on the first functional layer.

[0062] The active layer 12 may include at least one of a single quantum well structure, a multiple quantum well (MQW) structure, a quantum wire structure, and a quantum dot structure. The active layer 12 may include a well layer and a barrier layer formed of a GaN-based semiconductor material.

[0063] For example, the well layer may include Al x Ga 1-x N layer, wherein x is the percentage of the mass of Al element to the sum of the mass of Al element and Ga element, 1≥x≥0; and / or the barrier layer may include Al y Ga 1-y N layer, wherein y is the percentage of the mass of the Al element to the sum of the masses of the Al element and the Ga element, and 1 ≥ y ≥ 0. The band gap width of the well layer is smaller than the band gap width of the barrier layer.

[0064] The formation process of the well layer and / or the barrier layer may include: atomic layer deposition (ALD), chemical vapor deposition (CVD), molecular beam epitaxy (MBE), plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), metal-organic chemical vapor deposition (MOCVD), or a combination thereof.

[0065] The well layer and / or barrier layer may be doped with Al or not doped with Al. Not doping with Al can improve the crystal quality of the layer itself, but doping with Al can reduce its resistance.

[0066] Multiple layers of well layers and barrier layers can be alternately formed into a multi-quantum well structure, further improving the luminous efficiency.

[0067] Next, refer to Figure 1 Step S3 in Figure 2 and Figure 3 As shown, a second functional layer is formed on the active layer 12 . The second functional layer is a hole-providing layer 13 . The material of the second functional layer includes at least three elements: Al, Ga, and N.

[0068] The hole supply layer 13 may be a P-type semiconductor, such as a P-type III-V compound. The P-type doping element may include at least one of Mg, Zn, Ca, Sr, or Ba. In some embodiments, the material of the hole supply layer 13 includes AlGaN, that is, only includes Al, Ga, and N. More specifically, the ratio of Al, Ga, and N is not limited, that is, the material is Al n Ga 1-n N, where n is the percentage of the mass of Al to the sum of the masses of Al and Ga, 1>n>0. In some embodiments, the material of the hole supply layer 13 may include In, P, and other elements in addition to Al, Ga, and N.

[0069] The hole supply layer 13 may include one or more layers.

[0070] Afterwards, refer to Figure 1 Step S4 in Figures 4 to 6As shown, the second functional layer and the active layer 12 are patterned to expose a portion of the first functional layer, and an N-type transition layer 141 is formed on the exposed first functional layer. The material of the N-type transition layer 141 is GaN.

[0071] Reference Figure 4 As shown, patterning the second functional layer and the active layer 12 may include: first forming a photoresist mask layer on the second functional layer; then exposing the photoresist mask layer to develop a photoresist pattern; and then dry etching or wet etching the second functional layer and the active layer 12 using the photoresist pattern.

[0072] Specifically, before forming the photoresist mask layer, a stripping solution (dimethyl sulfoxide) can be used to remove the photoresist mask layer at 70°C to 100°C under ultrasonic conditions. Figure 2 and Figure 3 The intermediate structure shown is cleaned to remove surface organic particles; and H2SO4:H2O2:H2O (5:1:1) is used to clean at 80°C to 90°C to remove surface metal particles and surface oxide layer;

[0073] Next, the surface of the second functional layer is coated with a thickening agent HMDS (hexamethyldisilazane) to modify the surface of the second functional layer from hydrophilic to hydrophobic.

[0074] After etching, the remaining photoresist pattern can be removed by ashing.

[0075] Reference Figure 5 As shown, after patterning the second functional layer and the active layer 12 , a mask layer 18 may be formed on the second functional layer and the exposed first functional layer.

[0076] The mask layer 18 may be made of an insulating material, such as silicon dioxide, silicon nitride, etc., and may be formed into a layer of uniform thickness by using a physical vapor deposition method or a chemical vapor deposition method.

[0077] Reference Figure 6 As shown, the mask layer 18 is patterned to remove the mask layer 18 in the area where the N-type transition layer 141 is to be formed. The remaining mask layer 18 prevents the N-type transition layer 141 from being formed thereon in subsequent steps. In other words, the area of ​​the remaining mask layer 18 must be complementary to the area where the N-type transition layer 141 is to be formed.

[0078] The formation process of the N-type transition layer 141 may refer to the formation process of the well layer and / or the barrier layer.

[0079] Reference Figure 6 As shown, in order to improve the quality of the N-type transition layer 141, an N-type gradient material layer 161 may be formed on the exposed first functional layer. The material of the N-type gradient material layer 161 may be Al t Ga 1-tN, where t is the percentage of the mass of Al to the sum of the masses of Al and Ga, and m>t>0. That is, the mass percentage of Ga in the N-type graded material layer 161 is between the mass percentage of Ga in the first functional layer and the mass percentage of Ga in the N-type transition layer 141. In the N-type graded material layer 161, the mass percentage of Ga can gradually increase along the thickness direction from the first functional layer to the N-type transition layer 141.

[0080] According to the material of the first functional layer, the material of the N-type graded material layer 161 may include elements such as In and P in addition to Al, Ga, and N.

[0081] The formation process of the N-type graded material layer 161 may refer to the formation process of the well layer and / or the barrier layer.

[0082] Next, refer to Figure 1 Step S5 in Figure 7 As shown, an N-electrode 151 is formed on the N-type transition layer 141 , and an ohmic contact is formed between the N-type transition layer 141 and the N-electrode 151 ; a P-electrode 152 is formed on the second functional layer, and an ohmic contact is formed between the second functional layer and the P-electrode 152 .

[0083] Reference Figure 7 As shown, the material of the N-electrode 151 and the P-electrode 152 can be at least one of Ti, Al, Ni, and Au. For example, the N-electrode 151 and the P-electrode 152 can be a stacked structure of Ti layer / Al layer / Ni layer / Au layer, or a stacked structure of Ti layer / Al layer, or a stacked structure of Ni layer / Au layer, and can be formed by sputtering.

[0084] In some embodiments, the P-electrode 152 on the surface of the second functional layer can be sputtered in the same process as the N-electrode 151 on the surface of the N-type transition layer 141. In this case, the mask layer 18 is removed from a portion of the surface of the second functional layer before forming the P-electrode 152. The P-electrode 152 on the surface of the second functional layer requires high-temperature annealing to form a P-type ohmic contact.

[0085] In some embodiments, the P-electrode 152 on the surface of the second functional layer can be sputtered before or after the N-electrode 151 on the surface of the N-type transition layer 141 is formed.

[0086] Since the N-type transition layer 141 is made of GaN, low contact resistance can be formed between the N-electrode 151 and the N-type transition layer 141 without annealing. In addition, the electron supply layer 11 does not need to be made too thick, which can improve the quality of the electron supply layer 11.

[0087] In the fabrication method of a UV LED in this embodiment, an N-type transition layer 141 is formed on the electron supply layer 11. The material of the electron supply layer 11 includes at least Al, Ga, and N, and the material of the N-type transition layer 141 is GaN. An N-electrode 151 is formed on the N-type transition layer 141, and an ohmic contact is formed between the N-type transition layer 141 and the N-electrode 151. Compared to directly forming the N-electrode 151 on an aluminum-containing GaN-based material and then performing high-temperature annealing to form an ohmic contact, this method avoids annealing and the degradation of the electron supply layer 11 performance caused by the high temperature during the annealing process. It also reduces the electron-hole recombination rate in the active layer 12. Consequently, the luminous efficiency of the UV LED 1 can be improved.

[0088] Reference Figure 7 As shown, the ultraviolet LED 1 of the first embodiment of the present invention includes:

[0089] The electron supply layer 11, the hole supply layer 13, and the active layer 12 between the electron supply layer 11 and the hole supply layer 13, the materials of the electron supply layer 11 and the hole supply layer 13 all include at least three elements: Al, Ga, and N; the electron supply layer 11 has an N-type transition layer 141, and the material of the N-type transition layer 141 is GaN; the N-type transition layer 141 is provided with an N-electrode 151, and an ohmic contact is formed between the N-type transition layer 141 and the N-electrode 151; the hole supply layer 13 is provided with a P-electrode 152, and an ohmic contact is formed between the hole supply layer 13 and the P-electrode 152.

[0090] The electron supply layer 11 may include one or more layers. The electron supply layer 11 may be an N-type semiconductor, such as an N-type III-V compound. The N-type doping element may include at least one of Si, Ge, Sn, Se, or Te. In some embodiments, the material of the electron supply layer 11 includes AlGaN, that is, only includes Al, Ga, and N. More specifically, the ratio of the three elements Al, Ga, and N is not limited, that is, the material is Al m Ga 1-m N, where m is the percentage of the mass of Al to the sum of the masses of Al and Ga, 1>m>0. In some embodiments, the material of the electron supply layer 11 may include In, P, and other elements in addition to Al, Ga, and N.

[0091] The active layer 12 may include at least one of a single quantum well structure, a multiple quantum well (MQW) structure, a quantum wire structure, and a quantum dot structure. The active layer 12 may include a well layer and a barrier layer formed of a GaN-based semiconductor material.

[0092] For example, the well layer may include Al x Ga 1-xN layer, wherein x is the percentage of the mass of Al element to the sum of the mass of Al element and Ga element, 1≥x≥0; and / or the barrier layer may include Al y Ga 1-y N layer, where y is the percentage of the mass of Al to the sum of the masses of Al and Ga, and 1 ≥ y ≥ 0. The band gap of the well layer is smaller than the band gap of the barrier layer. The well layer and / or the barrier layer may be doped with Al or may not be doped with Al.

[0093] Multiple layers of well layers and barrier layers can be alternately formed into a multi-quantum well structure.

[0094] The hole supply layer 13 may include one or more layers. The hole supply layer 13 may be a P-type semiconductor, such as a P-type III-V compound. The P-type doping element may include at least one of Mg, Zn, Ca, Sr, or Ba. In some embodiments, the material of the hole supply layer 13 includes AlGaN, that is, only includes Al, Ga, and N. More specifically, the ratio of Al, Ga, and N is not limited, that is, the material is AlGaN. n Ga 1-n N, where n is the percentage of the mass of Al to the sum of the masses of Al and Ga, 1>n>0. In some embodiments, the material of the hole supply layer 13 may include In, P, and other elements in addition to Al, Ga, and N.

[0095] The upper surface of the hole supply layer 13, the side surfaces of the hole supply layer 13 and the active layer 12, and the upper surface of the electron supply layer 11 may have a mask layer 18, and the region of the mask layer 18 is complementary to the region of the N-type transition layer 141. The mask layer 18 may be an insulating material.

[0096] An N-type gradient material layer 161 may be provided between the electron supply layer 11 and the N-type transition layer 141. The material of the N-type gradient material layer 161 may be Al t Ga 1-t N, where t is the percentage of the mass of Al to the sum of the masses of Al and Ga, and m>t>0. That is, the mass percentage of Ga in the N-type graded material layer 161 is between the mass percentage of Ga in the electron supply layer 11 and the mass percentage of Ga in the N-type transition layer 141. In the N-type graded material layer 161, the mass percentage of Ga can gradually increase along the thickness direction from the electron supply layer 11 to the N-type transition layer 141.

[0097] According to the material of the electron supply layer 11 , the material of the N-type graded material layer 161 may include elements such as In and P in addition to Al, Ga, and N.

[0098] The material of the N-electrode 151 and the P-electrode 152 can be at least one of Ti, Al, Ni, and Au. For example, the N-electrode 151 and the P-electrode 152 can be a stacked structure of Ti layer / Al layer / Ni layer / Au layer, a stacked structure of Ti layer / Al layer, or a stacked structure of Ni layer / Au layer.

[0099] Since the N-type transition layer 141 is made of GaN, low contact resistance can be formed between the N-electrode 151 and the N-type transition layer 141 without annealing. In addition, the electron supply layer 11 does not need to be made too thick, which can improve the quality of the electron supply layer 11.

[0100] Figure 8 FIG. 4 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a second embodiment of the present invention.

[0101] Reference Figure 8 As shown, the structure of the ultraviolet LED 2 of the second embodiment is substantially the same as that of the ultraviolet LED 1 of the first embodiment, with the only difference being that the N-type transition layer 141 is an N-type heavily ion-doped GaN layer 141 ′.

[0102] The N-type ion heavily doped GaN layer 141 ′ on the electron supply layer 11 can provide more electrons to participate in conduction compared to the N-type transition layer 141 made of GaN.

[0103] In the N-type ion heavily doped GaN layer 141 ′, the doping concentration may be greater than 1E19 / cm 3 for different N-type ions.

[0104] The process of forming the N-type ion heavily doped GaN layer 141 ′ may include: doping N-type ions while growing, or performing N-type ion implantation after epitaxial growth of the GaN layer.

[0105] Figure 9 FIG. 4 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a third embodiment of the present invention.

[0106] Reference Figure 9 As shown, the structure of the ultraviolet LED 3 of the third embodiment is substantially the same as that of the ultraviolet LEDs 1 and 2 of the first and second embodiments, with the only difference being that an electron blocking layer 17 is provided between the hole-supplying layer 13 and the active layer 12 .

[0107] The electron blocking layer 17 can prevent electrons from entering the hole supply layer 13 from the active layer 12, thereby increasing the probability of electrons and holes being recombined in the active layer 12 and improving the luminous efficiency. The electron blocking layer 17 may include Al z Ga 1-z N layer, wherein z is the percentage of the mass of the Al element to the sum of the masses of the Al element and the Ga element, 1≥z≥0.

[0108] Accordingly, the manufacturing method is substantially the same as the manufacturing method of the ultraviolet LED of Examples 1 and 2, with the only difference being that a step is performed between step S2 and step S3: an electron blocking layer 17 is formed on the active layer 12; and in step S4, the second functional layer, the electron blocking layer 17 and the active layer 12 are patterned.

[0109] Figure 10 FIG. 4 is a schematic diagram of the cross-sectional structure of an ultraviolet LED according to a fourth embodiment of the present invention.

[0110] Reference Figure 10 As shown, the structure and manufacturing method of the UV LED 4 of this fourth embodiment are substantially the same as those of the UV LED 1 of the first embodiment. The only differences are: the first functional layer is a hole supply layer 13, and the second functional layer is an electron supply layer 11; a P-type transition layer 142 is formed on the exposed first functional layer, and the material of the P-type transition layer 142 is GaN; a P-electrode 152 is formed on the P-type transition layer 142, and an ohmic contact is formed between the P-type transition layer 142 and the P-electrode 152; and an N-electrode 151 is formed on the second functional layer, and an ohmic contact is formed between the second functional layer and the N-electrode 151.

[0111] Reference Figure 10 As shown, in order to improve the quality of the P-type transition layer 142, a P-type gradient material layer 162 may be formed on the exposed first functional layer. The material of the P-type gradient material layer 162 may be Al p Ga 1-p N, where p is the percentage of the mass of Al to the sum of the masses of Al and Ga, and m>p>0. That is, the mass percentage of Ga in the P-type graded material layer 162 is between the mass percentage of Ga in the first functional layer and the mass percentage of Ga in the P-type transition layer 142. In the P-type graded material layer 162, the mass percentage of Ga can gradually increase along the thickness direction from the hole-supplying layer 13 to the P-type transition layer 142.

[0112] According to the material of the hole-supplying layer 13 , the material of the P-type graded material layer 162 may include elements such as In and P in addition to Al, Ga, and N.

[0113] The formation process of the P-type graded material layer 162 may refer to the formation process of the well layer and / or the barrier layer.

[0114] Since the P-type transition layer 142 is made of GaN, the P-type ohmic contact can be formed with low resistance without annealing. In addition, the hole supply layer 13 does not need to be made too thick, which can improve the quality of the hole supply layer 13.

[0115] Figure 11 FIG. 4 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a fifth embodiment of the present invention.

[0116] Reference Figure 11 As shown, the structure of the ultraviolet LED 5 of the fifth embodiment is substantially the same as that of the ultraviolet LED 4 of the fourth embodiment, with the only difference being that the P-type transition layer 142 is a P-type ion heavily doped GaN layer 142 ′.

[0117] The P-type ion heavily doped GaN layer 142 ′ on the hole-supplying layer 13 can provide more holes to participate in conduction compared to the P-type transition layer 142 made of GaN.

[0118] In the GaN layer 142 ′ heavily doped with P-type ions, the doping concentration may be greater than 1E19 / cm 3 for different P-type ions.

[0119] The process of forming the P-type ion heavily doped GaN layer 142 ′ may include: doping P-type ions while growing, or epitaxially growing a GaN layer and then implanting P-type ions.

[0120] Figure 12 FIG. 4 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a sixth embodiment of the present invention.

[0121] Reference Figure 12 As shown, the structure of the ultraviolet LED 6 of the sixth embodiment is substantially the same as that of the ultraviolet LEDs 1, 2, and 3 of the first, second, and third embodiments. The only difference is that the surface of the hole-supplying layer 13 further comprises a P-type transition layer 142, on which a P-electrode 152 is formed, forming an ohmic contact between the P-type transition layer 142 and the P-electrode 152.

[0122] Correspondingly, the manufacturing method is substantially the same as the manufacturing method of the ultraviolet LED of Examples 1, 2 and 3, with the only difference being that: in step S4, a P-type transition layer 142 is formed on the second functional layer and an N-type transition layer 141 is formed on the exposed first functional layer, and the material of the P-type transition layer 142 and the N-type transition layer 141 is GaN; in step S5, an N-electrode 151 is formed on the N-type transition layer 141, and an ohmic contact is formed between the N-type transition layer 141 and the N-electrode 151; and a P-electrode 152 is formed on the P-type transition layer 142, and an ohmic contact is formed between the P-type transition layer 142 and the P-electrode 152.

[0123] The P-electrode 152 on the second functional layer and the N-electrode 151 on the first functional layer of the UV LED 6 can form low-resistance P-type ohmic contacts and low-resistance N-type ohmic contacts respectively without annealing.

[0124] Figure 13 FIG. 4 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a seventh embodiment of the present invention.

[0125] Reference Figure 13As shown, the structure of the UV LED 7 of the seventh embodiment is substantially the same as that of the UV LED 6 of the sixth embodiment. The only difference is that the N-type transition layer 141 on the surface of the electron supply layer 11 is an N-type ion-heavy doped GaN layer 141', and the P-type transition layer 142 on the surface of the hole supply layer 13 is a P-type ion-heavy doped GaN layer 142'.

[0126] The P-type ion heavily doped GaN layer 142 ′ on the hole-supplying layer 13 can provide more holes to participate in conduction compared to the P-type transition layer 142 made of GaN.

[0127] Figure 14 FIG. 4 is a schematic cross-sectional structural diagram of an ultraviolet LED according to an eighth embodiment of the present invention.

[0128] Reference Figure 14 As shown, the structure of the UV LED 8 of the eighth embodiment is substantially the same as that of the UV LED 7 of the seventh embodiment. The only difference is that an N-type transition layer 161 and an N-type ion-doped GaN layer 141' are sequentially formed on the P-type ion-doped GaN layer 142'; and a P-electrode 152 is formed on the N-type ion-doped GaN layer 141'.

[0129] The heavily P-type ion-doped GaN layer 142' and the heavily N-type ion-doped GaN layer 141' can form a tunnel junction. Research has shown that as the voltage applied between the P-electrode 152 and the N-electrode 151 increases, the tunneling current of the tunnel junction increases rapidly. The UV LED 8 of this embodiment can form a P-type ohmic contact with low contact resistance through the tunnel junction.

[0130] In the manufacturing method of the ultraviolet LED 8, the N-type transition layer 161 and the N-type ion-doped GaN layer 141' on the P-type ion-doped GaN layer 142' can be manufactured simultaneously with the N-type transition layer 161 and the N-type ion-doped GaN layer 141' on the electron supply layer 11, and the processes are compatible.

[0131] In some embodiments, the N-type transition layer 161 may be omitted, and the P-type ion heavily doped GaN layer 142 ′ is in direct contact with the N-type ion heavily doped GaN layer 141 ′ to form a tunnel junction.

[0132] Figure 15 FIG. 4 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a ninth embodiment of the present invention.

[0133] Reference Figure 15As shown, the structure of the UV LED 9 of this ninth embodiment is substantially the same as that of the UV LEDs 1, 2, 3, 4, 5, 6, 7, and 8 of the first to eighth embodiments. The only difference is that only the surface of the hole-supplying layer 13 has a P-type transition layer 142, and a P-electrode 152 is formed on the P-type transition layer 142, forming an ohmic contact between the P-type transition layer 142 and the P-electrode 152.

[0134] Correspondingly, the manufacturing method is substantially the same as the manufacturing method of the ultraviolet LED of Examples 1 to 8, with the only difference being that: in step S4, a P-type transition layer 142 is formed on the second functional layer, and the material of the P-type transition layer 142 is GaN; in step S5, an N-electrode 151 is formed on the first functional layer, and an ohmic contact is formed between the first functional layer and the N-electrode 151; and a P-electrode 152 is formed on the P-type transition layer 142, and an ohmic contact is formed between the P-type transition layer 142 and the P-electrode 152.

[0135] The P-electrode 152 on the second functional layer of the ultraviolet LED 9 can form a low-resistance P-type ohmic contact without annealing.

[0136] Figure 16 FIG. 1 is a schematic cross-sectional structural diagram of an ultraviolet LED according to a tenth embodiment of the present invention.

[0137] Reference Figure 16 As shown, the structure of the ultraviolet LED 10 of the tenth embodiment is substantially the same as that of the ultraviolet LEDs 1, 2, 3, 4, 5, 6, 7, 8, and 9 of the first to ninth embodiments, with the only difference being that the ultraviolet LED 10 further includes a substrate 100.

[0138] The substrate 100 may be sapphire, silicon carbide, silicon or GaN-based materials.

[0139] Accordingly, the manufacturing method is substantially the same as the manufacturing method of the ultraviolet LED of the first to ninth embodiments, with the only difference being that in step S1 , a substrate 100 is provided, and a first functional layer is formed on the substrate 100 .

[0140] The method for forming the first functional layer refers to the method for forming the second functional layer.

[0141] Before forming the first functional layer on the substrate 100, a nucleation layer and a buffer layer (not shown) may be formed in sequence. The nucleation layer may be made of, for example, AlN, AlGaN, etc., and the buffer layer may be made of at least one of AlN, GaN, AlGaN, and AlInGaN. The buffer layer may be formed in the same manner as the first functional layer. The nucleation layer may alleviate lattice mismatch and thermal mismatch issues between the epitaxially grown semiconductor layer, such as the first functional layer, and the substrate 100. The buffer layer may reduce the dislocation density and defect density of the epitaxially grown semiconductor layer, thereby improving crystal quality.

[0142] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A UV LED, characterized in that: include: An electron supply layer (11), a hole supply layer (13), and an active layer (12) between the electron supply layer (11) and the hole supply layer (13), wherein the materials of the electron supply layer (11) and the hole supply layer (13) both include at least three elements: Al, Ga, and N; an N-type transition layer (141) is provided on the electron supply layer (11), and an N-type gradient material layer (161) is provided between the electron supply layer (11) and the N-type transition layer (141); the material of the N-type transition layer (141) is GaN; an N-electrode (151) is provided on the N-type transition layer (141), and an ohmic contact is formed between the N-type transition layer (141) and the N-electrode (151), so that a low contact resistance can be formed between the N-electrode (151) and the N-type transition layer (141) without annealing; A P-type transition layer (142) is provided on the hole supply layer (13), and the material of the P-type transition layer (142) is GaN; a P-electrode (152) is provided on the P-type transition layer (142), and an ohmic contact is formed between the P-type transition layer (142) and the P-electrode (152); Wherein, a P-type gradient material layer (162) is provided between the hole supply layer (13) and the P-type transition layer (142); The N-type transition layer (141) is an N-type ion heavily doped GaN layer (141'), and the P-type transition layer (142) is a P-type ion heavily doped GaN layer (142'); Between the P-type ion heavily doped GaN layer (142') and the P electrode (152) are an N-type gradient material layer (161) and an N-type ion heavily doped GaN layer (141') sequentially stacked on the P-type ion heavily doped GaN layer (142').

2. The ultraviolet LED according to claim 1, characterized in that The N-type gradient material layer (161) comprises at least three elements: Al, Ga, and N, and the mass percentage of Ga in the N-type gradient material layer (161) is greater than the mass percentage of Ga in the electron supply layer (11); and / or The P-type gradient material layer (162) comprises at least three elements: Al, Ga, and N; the mass percentage of Ga in the P-type gradient material layer (162) is greater than the mass percentage of Ga in the hole supply layer (13).

3. The ultraviolet LED according to claim 1, characterized in that The material of the electron supply layer (11) and / or the hole supply layer (13) is AlGaN.

4. The ultraviolet LED according to claim 1, characterized in that The active layer (12) includes a quantum well structure.

5. The ultraviolet LED according to claim 4, characterized in that The quantum well structure is a multi-quantum well structure.

6. The ultraviolet LED according to claim 4 or 5, characterized in that: The quantum well structure includes Al x Ga 1-x N layer and Al y Ga 1-y N layers, 1≥x≥0, 1≥y≥0.

7. The ultraviolet LED according to claim 1, characterized in that An electron blocking layer (17) is provided between the hole supply layer (13) and the active layer (12).

8. The ultraviolet LED according to claim 1, characterized in that The material of the N electrode (151) and / or the P electrode (152) is at least one of Ti, Al, Ni, and Au.

9. The ultraviolet LED according to claim 1, characterized in that A mask layer (18) is provided on the electron supply layer (11) and the hole supply layer (13); the mask layer (18) is made of an insulating material; and a region of the mask layer (18) is complementary to a region of the N-type transition layer (141) and the P-type transition layer (142).

10. A method for manufacturing an ultraviolet LED, characterized in that: include: Providing a first functional layer, wherein the first functional layer is an electron supply layer (11), and the material of the first functional layer includes at least three elements: Al, Ga, and N; forming an active layer (12) on the first functional layer; forming a second functional layer on the active layer (12), wherein the second functional layer is a hole supply layer (13), and the material of the second functional layer includes at least three elements: Al, Ga, and N; Patterning the second functional layer and the active layer (12), exposing a portion of the first functional layer, and forming a transition layer on the exposed first functional layer, wherein the transition layer on the electron supply layer (11) is an N-type transition layer (141), and the material of the N-type transition layer (141) is GaN; An N-electrode (151) is formed on the N-type transition layer (141), and an ohmic contact is formed between the N-type transition layer (141) and the N-electrode (151), so that a low contact resistance can be formed between the N-electrode (151) and the N-type transition layer (141) without annealing; Wherein, before forming the N-type transition layer (141) on the electron supply layer (11), an N-type gradient material layer (161) is first formed; forming a transition layer on the second functional layer, wherein the transition layer on the hole supply layer (13) is a P-type transition layer (142), and the material of the P-type transition layer (142) is GaN; forming a P-electrode (152) on the P-type transition layer (142), and forming an ohmic contact between the P-type transition layer (142) and the P-electrode (152); Wherein, before forming the P-type transition layer (142) on the hole-supplying layer (13), a P-type gradient material layer (162) is first formed; The N-type transition layer (141) is an N-type ion heavily doped GaN layer (141'), and / or the P-type transition layer (142) is a P-type ion heavily doped GaN layer (142'); After forming the P-type ion heavily doped GaN layer (142') and before forming the P electrode (152), the method further comprises: sequentially forming a stacked N-type gradient material layer (161) and an N-type ion heavily doped GaN layer (141') on the P-type ion heavily doped GaN layer (142'); The N-type gradient material layer (161) and the N-type ion heavily doped GaN layer (141') on the P-type ion heavily doped GaN layer (142') are formed simultaneously with the N-type gradient material layer (161) and the N-type ion heavily doped GaN layer (141') on the electron supply layer (11).

11. The method for manufacturing an ultraviolet LED according to claim 10, wherein: The N-type gradient material layer (161) comprises at least three elements: Al, Ga, and N, and the mass percentage of Ga in the N-type gradient material layer (161) is greater than the mass percentage of Ga in the electron supply layer (11); And / or the P-type gradient material layer (162) includes at least three elements: Al, Ga, and N, and the mass percentage of Ga in the P-type gradient material layer (162) is greater than the mass percentage of Ga in the hole supply layer (13).

12. The method for manufacturing an ultraviolet LED according to claim 10, wherein: Before forming a transition layer on the second functional layer and / or the exposed first functional layer, a mask layer (18) is formed on the second functional layer and the exposed first functional layer, wherein the mask layer (18) is an insulating material, and an area of ​​the mask layer (18) is complementary to an area of ​​the transition layer to be formed.

13. The method for manufacturing an ultraviolet LED according to claim 10, wherein: The material of the electron supply layer (11) and / or the hole supply layer (13) is AlGaN.

14. The method for manufacturing an ultraviolet LED according to claim 10, wherein: The active layer (12) includes a quantum well structure.

15. The method for manufacturing an ultraviolet LED according to claim 14, wherein: The quantum well structure is a multi-quantum well structure.

16. The method for manufacturing an ultraviolet LED according to claim 14 or 15, wherein: The quantum well structure includes Al x Ga 1-x N layer and Al y Ga 1-y N layers, 1≥x≥0, 1≥y≥0.

17. The method for manufacturing an ultraviolet LED according to claim 10, wherein: An electron blocking layer (17) is formed between the hole supply layer (13) and the active layer (12).

18. The method for manufacturing an ultraviolet LED according to claim 10, wherein: The material of the N electrode (151) and / or the P electrode (152) is at least one of Ti, Al, Ni, and Au.

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