A vertical UV LED chip and preparation method thereof

Abstract

The present invention discloses a vertical UV LED chip and a preparation method thereof. The chip comprises a conductive substrate, an epitaxial layer, a high-aluminum layer, a transparent conductive layer and an electrode structure. The electrode structure is arranged between the conductive substrate and the transparent conductive layer. The high-aluminum layer is arranged between the transparent conductive layer and the epitaxial layer. The high-aluminum layer is provided with a plurality of through holes, which are arranged in an array. The high-aluminum layer is composed of Al x Ga 1‑ x N, x is 0.15-0.45, the transparent conductive layer is filled into the through hole and forms a conductive connection with the epitaxial layer. The chip of the present invention improves the light uniformity and brightness by improving the core current expansion performance.

Description

Technical Field

[0001] The present invention relates to the technical field of light emitting diodes, and in particular to a vertical UV LED chip and a preparation method thereof. Background Art

[0002] UV LEDs are widely used in the fields of manicure, disinfection, industrial curing, etc. Since it is difficult to obtain bulk material substrates of group III nitrides for UV LED chips, the epitaxy of AlGaN ultraviolet light-emitting diodes can usually only be carried out on heterogeneous substrates such as sapphire. Since the lattice constants of these heterogeneous substrates are different from those of AlGaN materials with high aluminum components, and since the surface mobility of Al atoms is very low, during the epitaxial growth of AlGaN with high aluminum components, it is difficult for Al atoms reaching the reaction interface to migrate to the lowest energy points such as steps or kinks, so ideal two-dimensional epitaxial growth cannot be achieved, resulting in the AlGaN film with high Al components consisting of many small sub-grains distributed in a mosaic shape. Between these sub-grains, a density of up to 10 9 ~10 11 cm -2 Threading dislocations in the material act as non-radiative recombination centers, and too high a dislocation density will strongly reduce the internal quantum efficiency of the LED.

[0003] In addition, due to the influence of the epitaxial material (AlGaN), the energy level of the epitaxial layer is relatively high, and the current is not easy to diffuse in the chip, so the brightness of the chip cannot be improved. If the current diffusion performance of the UV LED chip can be improved, the luminous uniformity and brightness of the UV LED chip can be improved. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a vertical UV LED chip and a preparation method thereof, so as to improve the light emission uniformity and brightness of the UV LED chip by improving the current expansion performance of the chip.

[0005] In order to solve the above technical problems, the present invention provides a vertical UV LED chip, including a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al x Ga 1-x N, x is 0.15-0.45, the transparent conductive layer is filled into the through hole and forms a conductive connection with the epitaxial layer.

[0006] As an improvement of the above solution, the size of the through hole is (3-10)*(3-10) μm;

[0007] The thickness of the high aluminum layer is 10-100 nm.

[0008] As an improvement of the above solution, the high aluminum layer is provided with m rows and n columns of through holes, m≥3, n≥3, wherein the through holes in odd rows are on even columns, and the through holes in even rows are on odd columns.

[0009] As an improvement to the above solution, the through holes in the odd number rows are correspondingly arranged on the center lines of two adjacent through holes in the even number rows;

[0010] The distance between through holes in the same row or column is 35-40 μm.

[0011] As an improvement of the above scheme, x is 0.2 to 0.4;

[0012] The high-aluminum layer is subjected to oxidation treatment so that the aluminum on the surface of the high-aluminum layer is oxidized to form aluminum oxide.

[0013] As an improvement of the above solution, the electrode structure includes an Ag layer, a TiW layer and a Pt layer, the Ag layer is arranged between the transparent conductive layer and the TiW layer, and the Pt layer is arranged on the TiW layer.

[0014] Accordingly, the present invention also provides a method for preparing a vertical UV LED chip, comprising the following steps:

[0015] S1, forming an epitaxial layer on a substrate;

[0016] S2, forming Al on the epitaxial layer x Ga 1-x A high aluminum layer made of N, x is 0.15 to 0.45, wherein the high aluminum layer is provided with a plurality of through holes, and the through holes are arranged in an array;

[0017] S3, performing oxidation treatment on the high aluminum layer to oxidize aluminum on the surface of the high aluminum layer to form aluminum oxide;

[0018] S4, forming a transparent conductive layer on the high aluminum layer, and filling the transparent conductive layer into the through hole to form a conductive connection with the epitaxial layer;

[0019] S5, forming an electrode structure on the transparent conductive layer;

[0020] S6. Remove the substrate and bond the electrode structure to the conductive substrate.

[0021] As an improvement of the above scheme, in step S2, MOCVD is used to introduce TMAl, TMGa, NH3 and N2 at a temperature of 900-1300°C, with flow rates of 250-350sccm, 10-16sccm, 30-35SLM and 70-85SLM respectively, to form an Al epitaxial layer on the epitaxial layer.x Ga 1-x High aluminum layer made of N.

[0022] As an improvement of the above solution, in step S2, the high aluminum layer is etched by ICP etching or photolithography until the surface of the epitaxial layer is etched to form a plurality of through holes arranged in an array.

[0023] As an improvement of the above scheme, in step S3, the high-aluminum layer is placed in an oxidation device, oxygen is introduced, and the device is started to bombard the high-aluminum layer, and the treatment time is 5 to 15 minutes.

[0024] The implementation of the present invention has the following beneficial effects:

[0025] The vertical UV LED chip provided by the present invention is provided with Al on the epitaxial layer. x Ga 1-x The high-aluminum layer made of N, through the oxidation of aluminum in the high-aluminum layer into non-conductive aluminum oxide, plays the role of current blocking, allowing the current to diffuse evenly in the high-aluminum layer, making the high-aluminum layer a current expansion layer, thereby improving the current expansion performance of the chip, and then improving the brightness and luminous uniformity of the chip.

[0026] The present invention sets a plurality of through holes arranged in an array in the high aluminum layer, and sets a transparent conductive layer on the high aluminum layer and fills the through holes, so that the transparent conductive layer is in full contact with the high aluminum layer and the epitaxial layer, further improving the current expansion performance of the chip, and further improving the brightness and luminous uniformity of the chip.

[0027] The present invention further designs the arrangement of through holes and the distance between through holes, thereby improving the current expansion performance of the chip, improving the brightness and luminous uniformity of the chip, and allowing the transparent conductive layer to fully contact with the high aluminum layer and the epitaxial layer to avoid increasing the influence of the high aluminum layer on the chip voltage, thereby ensuring the stability of the chip voltage.

[0028] The electrode structure of the present invention uses a metal stacked structure of Ag / TiW / Pt, which can be well bonded to a conductive substrate through AuSn to form a vertical UV LED chip.

[0029] The preparation method of the vertical UV LED chip of the present invention is simple. After forming the epitaxial layer, MOCVD is continuously used to form the high aluminum layer. The process is simple, the material is easy to obtain, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the vertical UV LED chip of the present invention;

[0031] Figure 2 It is a top view of the high aluminum layer of the present invention. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0033] See also Figure 1 and Figure 2 The present invention provides a vertical UV LED chip, comprising a conductive substrate 10, an epitaxial layer 20, a high aluminum layer 30, a transparent conductive layer 40 and an electrode structure 50, wherein the electrode structure 50 is arranged between the conductive substrate 10 and the transparent conductive layer 40, the high aluminum layer 30 is arranged between the transparent conductive layer 40 and the epitaxial layer 20, the high aluminum layer 30 is provided with a plurality of through holes 41, the through holes 41 are arranged in an array, and the high aluminum layer 30 is composed of Al x Ga 1-x N, the transparent conductive layer 40 is filled into the through hole 41 and forms a conductive connection with the epitaxial layer 20.

[0034] Since the aluminum content in the high aluminum layer 30 of the present invention is high, part of the aluminum in the high aluminum layer 30 will be oxidized into non-conductive aluminum oxide when it encounters oxygen. This part of non-conductive aluminum oxide can play a role in current blocking, thereby allowing the current to diffuse evenly in the high aluminum layer 30, making the high aluminum layer 30 a current expansion layer, thereby improving the current expansion performance of the chip.

[0035] In addition, since a plurality of through holes 31 are provided in the high aluminum layer 30 , the transparent conductive layer 40 filled in the through holes 31 is in full contact with the high aluminum layer 30 and the epitaxial layer 20 , further improving the current expansion performance of the chip.

[0036] Among them, the height of the aluminum content in the high aluminum layer 30 plays an important role in the current expansion of the high aluminum layer 30. If the aluminum content in the high aluminum layer 30 is too low, it is difficult to oxidize to form non-conductive aluminum oxide, and the current diffusion effect cannot be achieved; if the aluminum content in the high aluminum layer 30 is too high, the high aluminum layer 30 is prone to crystal growth and cracking during formation, affecting the crystal structure of the entire high aluminum layer 30, and further affecting the optoelectronic performance of the chip. Preferably, the aluminum content in the high aluminum layer 30 is 0.15-0.45, that is, x is 0.15-0.45. More preferably, x is 0.2-0.4. Optimally, x is 0.2-0.35.

[0037] Among them, the material Al x Ga 1-x N can be well formed on the epitaxial layer 20 (less defects), because it has a high energy level and does not absorb ultraviolet light, and it contains Al, which can be oxidized into non-conductive aluminum oxide. Therefore, the present invention uses Al x Ga 1-x N is used to prepare the high aluminum layer 30.

[0038] If the present invention uses SiO2 to make the current blocking layer, wherein SiO2 is formed by deposition at a temperature of about 200-300°C, and has relatively high defects and absorbs purple light.

[0039] In addition to the aluminum content in the high aluminum layer 30 affecting the current expansion performance of the high aluminum layer 30, the size of the through hole 31 of the high aluminum layer 30 and the distance between the through holes 31 also play an important role in the current expansion performance of the high aluminum layer 30. If the size of the through hole 31 is too small, it is difficult for the transparent conductive layer 40 to fill it in and form a conductive connection with the epitaxial layer 20, which will affect the current expansion performance; if the size of the through hole 31 is too large, the current blocking area in the high aluminum layer 30 is too small, and a good current expansion effect cannot be achieved. Preferably, the size of the through hole 31 is (3~10)*(3~10)μm. Specifically, the size of the through hole 31 is 3*3μm, 4*4μm, 5*5μm, 6*6μm, 7*7μm, 8*8μm, 9*9μm or 10*10μm.

[0040] Specifically, the high aluminum layer 30 is provided with m rows and n columns of through holes 31, m≥3, n≥3, wherein the through holes 31 in odd rows are on even columns, and the through holes 31 in even rows are on odd columns. The present invention sets the positions of the through holes 31 in this cross-arrangement manner, which can further improve the current expansibility of the high aluminum layer 30 and make the current diffusion more uniform.

[0041] Preferably, the through holes 31 in an odd-numbered row are correspondingly arranged on the center lines of two adjacent through holes 31 in an even-numbered row.

[0042] Preferably, the distance between the through holes 31 in the same row or column is 35-40 μm.

[0043] The thickness of the high aluminum layer 30 is 10 to 100 nm. If the thickness of the high aluminum layer 30 is too thin, the current is easy to tunnel, and the current blocking and diffusion function cannot be achieved; if the thickness of the high aluminum layer 30 is too thick, the high aluminum layer 30 is easy to grow and crack, affecting the crystal structure of the entire high aluminum layer 30, and further affecting the optoelectronic performance of the chip. Preferably, the thickness of the high aluminum layer 30 is 20 to 80 nm. More preferably, the thickness of the high aluminum layer 30 is 25 to 60 nm.

[0044] Specifically, the conductive substrate 10 of the present invention is a conductive silicon substrate, which is bonded to the electrode structure 50 via AuSn, so an AuSn layer (not shown in the figure) is provided between the conductive substrate 10 and the electrode structure 50 .

[0045] The electrode structure 50 of the present invention is a metal laminate structure. Preferably, the electrode structure 50 includes an Ag layer 51, a TiW layer 52 and a Pt layer 53, wherein the Ag layer 51 is disposed between the transparent conductive layer 40 and the TiW layer 52, and the Pt layer 53 is disposed between the TiW layer 52 and the AuSn layer. Preferably, the transparent conductive layer 40 is an ITO layer, but is not limited thereto.

[0046] Specifically, the epitaxial layer 20 includes a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23. The active layer 22 is disposed between the first semiconductor layer 21 and the second semiconductor layer 23, and the high aluminum layer 30 is disposed on the second semiconductor layer 23. Preferably, a super lattice layer (not shown in the figure) is further disposed between the first semiconductor layer 21 and the active layer 22, and the super lattice layer is used to buffer the lattice mismatch between the first semiconductor layer 21 and the active layer 22 to reduce defects. x Ga 1-x N layer, active layer 22 is In y Ga 1-y N / A z Ga 1-z N multi-quantum well layer, the second semiconductor layer 23 is a p-type GaN layer.

[0047] The vertical UV LED chip provided by the present invention is provided with Al on the epitaxial layer 20. x Ga 1-x The high-aluminum layer 30 made of N, through the oxidation of aluminum in the high-aluminum layer 30 into non-conductive aluminum oxide, plays a role of current blocking, allowing the current to diffuse evenly in the high-aluminum layer 30, making the high-aluminum layer 30 a current spreading layer, thereby improving the current spreading performance of the chip, and then improving the brightness and luminous uniformity of the chip.

[0048] The present invention sets a plurality of through holes 31 arranged in an array in the high aluminum layer 30, and sets a transparent conductive layer 40 on the high aluminum layer 30 and fills the through holes 31, so that the transparent conductive layer 40 is in full contact with the high aluminum layer 30 and the epitaxial layer 20, further improving the current expansion performance of the chip, and further improving the brightness and luminous uniformity of the chip.

[0049] The present invention further designs the arrangement of the through holes 31 and the distance between the through holes 31, thereby improving the current expansion performance of the chip, improving the brightness and luminous uniformity of the chip, and allowing the transparent conductive layer 40 to fully contact with the high aluminum layer 30 and the epitaxial layer 20 to avoid increasing the influence of the high aluminum layer 30 on the chip voltage, thereby ensuring the stability of the chip voltage.

[0050] The electrode structure 50 of the present invention uses a metal stacked structure of Ag / TiW / Pt, which can be well bonded to the conductive substrate 10 through AuSn to form a vertical UV LED chip.

[0051] Accordingly, the present invention also provides a method for preparing a vertical UV LED chip, comprising the following steps:

[0052] S1, forming an epitaxial layer on a substrate;

[0053] Specifically, the substrate is a sapphire, silicon or silicon carbide substrate. The epitaxial layer is formed on the substrate by MOCVD, and the epitaxial layer includes a first semiconductor layer, an active layer and a second semiconductor layer, and the active layer is arranged between the first semiconductor layer and the second semiconductor layer. The first semiconductor layer is an n-type Al x Ga 1-x N layer, the active layer is In y Ga 1- y N / A z Ga 1-z N multi-quantum well layer, and the second semiconductor layer is a p-type GaN layer.

[0054] Preferably, a super lattice layer is further provided between the first semiconductor layer and the active layer, and the super lattice layer is used to buffer the lattice mismatch between the first semiconductor layer and the active layer to reduce defects.

[0055] S2, forming Al on the epitaxial layer x Ga 1-x A high aluminum layer made of N, wherein the high aluminum layer is provided with a plurality of through holes, and the through holes are arranged in an array;

[0056] Specifically, MOCVD is used to introduce TMAl, TMGa, NH3 and N2 at a temperature of 900-1300°C, with flow rates of 250-350sccm, 10-16sccm, 30-35SLM and 70-85SLM, respectively, to form an Al-based epitaxial layer. x Ga 1-x High aluminum layer made of N.

[0057] Among them, the height of the aluminum content in the high aluminum layer plays an important role in the current expansion of the high aluminum layer. If the aluminum content in the high aluminum layer is too low, it is difficult to oxidize to form non-conductive aluminum oxide, and the current diffusion effect cannot be achieved; if the aluminum content in the high aluminum layer is too high, the high aluminum layer is prone to crystal growth and cracking during formation, affecting the crystal structure of the entire high aluminum layer, and further affecting the optoelectronic performance of the chip. Preferably, the aluminum content in the high aluminum layer is 0.15-0.45, that is, x is 0.15-0.45. More preferably, x is 0.2-0.4. Optimally, x is 0.2-0.35.

[0058] It should be noted that the aluminum content in the high aluminum layer is controlled by the flow rate of various gases introduced in the present invention. If the formation temperature of the high aluminum layer and the flow rate of the introduced gas in the present invention exceed the above range, it is difficult to ensure that x is 0.15 to 0.45, thereby affecting the current expansion performance of the high aluminum layer.

[0059] The thickness of the high aluminum layer is 10 to 100 nm. If the thickness of the high aluminum layer is too thin, the current is easy to tunnel, and it cannot block and diffuse the current; if the thickness of the high aluminum layer is too thick, the high aluminum layer is easy to grow and crack, affecting the crystal structure of the entire high aluminum layer, and further affecting the optoelectronic performance of the chip. Preferably, the thickness of the high aluminum layer is 30 to 60 nm. More preferably, the thickness of the high aluminum layer is 30 to 50 nm.

[0060] Among them, the material Al x Ga 1-x N can be well formed on the epitaxial layer (less defects), because it has a high energy level and does not absorb violet light, and it contains Al, which can be oxidized into non-conductive aluminum oxide. Therefore, the present invention uses Al x Ga 1-x N is used to prepare the high aluminum layer.

[0061] If the present invention uses SiO2 to make the current blocking layer, wherein SiO2 is formed by deposition at a temperature of about 200-300°C, and has relatively high defects and absorbs purple light.

[0062] Specifically, the high aluminum layer is etched by ICP etching or photolithography until the surface of the epitaxial layer is etched to form a plurality of through holes arranged in an array.

[0063] Among them, in addition to the aluminum content in the high aluminum layer, the through-hole size and the distance between the through-holes in the high aluminum layer also play an important role in the current expansion performance of the high aluminum layer. If the size of the through-hole is too small, it is difficult for the transparent conductive layer to fill it and form a conductive connection with the epitaxial layer, which will affect the current expansion performance; if the size of the through-hole is too large, the current blocking area in the high aluminum layer is too small, and it cannot play a good current expansion role.

[0064] Preferably, the size of the through hole is (3-10)*(3-10) μm. Specifically, the size of the through hole is 3*3 μm, 4*4 μm, 5*5 μm, 6*6 μm, 7*7 μm, 8*8 μm, 9*9 μm or 10*10 μm.

[0065] Specifically, the high-aluminum layer is provided with m rows and n columns of through holes, m≥3, n≥3, wherein the through holes in odd rows are on even columns, and the through holes in even rows are on odd columns. The present invention sets the positions of the through holes in this cross-arrangement manner, which can further improve the current expansibility of the high-aluminum layer and make the current diffusion more uniform.

[0066] Preferably, the through holes in an odd-numbered row are correspondingly arranged on the center lines of two adjacent through holes in an even-numbered row.

[0067] Preferably, the distance between the through holes in the same row or column is 35-40 μm.

[0068] S3, performing oxidation treatment on the high aluminum layer to oxidize aluminum on the surface of the high aluminum layer to form aluminum oxide;

[0069] Specifically, the high-aluminum layer is placed in an oxidation device, oxygen is introduced, and the device is started to bombard the high-aluminum layer for a treatment time of 5 to 15 minutes. The oxidation device is preferably a plasma cleaner or a high-temperature oxidation furnace.

[0070] Due to the high aluminum content in the high aluminum layer, after oxidation treatment, part of the aluminum in the high aluminum layer will be oxidized into non-conductive aluminum oxide. This part of non-conductive aluminum oxide can act as a current barrier, allowing the current to diffuse evenly in the high aluminum layer, making the high aluminum layer a current expansion layer, thereby improving the current expansion performance of the chip.

[0071] S4, forming a transparent conductive layer on the high aluminum layer, and filling the transparent conductive layer into the through hole to form a conductive connection with the epitaxial layer;

[0072] Specifically, a deposition method is used to deposit a transparent conductive layer on the high aluminum layer, and the transparent conductive layer is filled into the through hole to form a conductive connection with the epitaxial layer.

[0073] Preferably, the transparent conductive layer is an ITO layer.

[0074] S5, forming an electrode structure on the transparent conductive layer;

[0075] Specifically, the electrode structure is formed on the transparent conductive layer by evaporation or sputtering. The electrode structure of the present invention is a metal laminated structure.

[0076] Preferably, the electrode structure comprises an Ag layer, a TiW layer and a Pt layer, the Ag layer is arranged between the transparent conductive layer and the TiW layer, and the Pt layer is arranged on the TiW layer.

[0077] S6, removing the substrate and bonding the electrode structure to the conductive substrate;

[0078] Specifically, a layer of AuSn is evaporated on the electrode structure, and then the electrode structure is bonded to the conductive substrate by bonding to form a vertical UV LED chip.

[0079] The vertical UV LED chip provided by the present invention is provided with Al on the epitaxial layer. x Ga 1-x The high-aluminum layer made of N, through the oxidation of aluminum in the high-aluminum layer into non-conductive aluminum oxide, plays the role of current blocking, allowing the current to diffuse evenly in the high-aluminum layer, making the high-aluminum layer a current expansion layer, thereby improving the current expansion performance of the chip, and then improving the brightness and luminous uniformity of the chip.

[0080] The present invention sets a plurality of through holes arranged in an array in the high aluminum layer, and sets a transparent conductive layer on the high aluminum layer and fills the through holes, so that the transparent conductive layer is in full contact with the high aluminum layer and the epitaxial layer, further improving the current expansion performance of the chip, and further improving the brightness and luminous uniformity of the chip.

[0081] The present invention further designs the arrangement of through holes and the distance between through holes, thereby improving the current expansion performance of the chip, improving the brightness and luminous uniformity of the chip, and allowing the transparent conductive layer to fully contact with the high aluminum layer and the epitaxial layer to avoid increasing the influence of the high aluminum layer on the chip voltage, thereby ensuring the stability of the chip voltage.

[0082] The electrode structure of the present invention uses a metal stacked structure of Ag / TiW / Pt, which can be well bonded to a conductive substrate through AuSn to form a vertical UV LED chip.

[0083] The preparation method of the vertical UV LED chip of the present invention is simple. After forming the epitaxial layer, MOCVD is continuously used to form the high aluminum layer. The process is simple, the material is easy to obtain, and the cost is low.

[0084] The present invention will be further described with specific embodiments below.

[0085] Example 1

[0086] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al 0.15 Ga 0.85 N, the transparent conductive layer is filled into the through hole and forms a conductive connection with the epitaxial layer;

[0087] The high aluminum layer is oxidized for 5 minutes and has a thickness of 10 nm. The size of the through hole is 3*3 μm.

[0088] Example 2

[0089] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al 0.2 Ga 0.8 N, the transparent conductive layer is filled into the through hole and forms a conductive connection with the epitaxial layer;

[0090] The high aluminum layer is oxidized for 8 minutes and has a thickness of 25 nm. The size of the through hole is 4*4 μm.

[0091] Example 3

[0092] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al 0.25 Ga 0.75 N, the transparent conductive layer is filled into the through hole and forms a conductive connection with the epitaxial layer;

[0093] The high aluminum layer is oxidized for 10 minutes and has a thickness of 40 nm. The size of the through hole is 5*5 μm.

[0094] Example 4

[0095] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al 0.3 Ga 0.7 N, the transparent conductive layer is filled into the through hole and forms a conductive connection with the epitaxial layer;

[0096] The high aluminum layer is oxidized for 12 minutes and has a thickness of 60 nm. The size of the through hole is 6*6 μm.

[0097] Example 5

[0098] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al 0.35 Ga 0.65 N, the transparent conductive layer is filled into the through hole and forms a conductive connection with the epitaxial layer;

[0099] The high aluminum layer is oxidized for 13 minutes and has a thickness of 70 nm. The size of the through hole is 7*7 μm.

[0100] Example 6

[0101] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al 0.4 Ga 0.6 N, the transparent conductive layer is filled into the through hole and forms a conductive connection with the epitaxial layer;

[0102] The high aluminum layer is oxidized for 14 minutes and has a thickness of 80 nm. The size of the through hole is 8*8 μm.

[0103] Example 7

[0104] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al 0.45 Ga 0.65 N, the transparent conductive layer is filled into the through hole and forms a conductive connection with the epitaxial layer;

[0105] The high aluminum layer is oxidized for 15 minutes and has a thickness of 100 nm. The size of the through hole is 10*10 μm.

[0106] Comparative Example 1

[0107] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a transparent conductive layer and an electrode structure, wherein the transparent conductive layer is arranged between the epitaxial layer and the electrode structure, and the conductive substrate is arranged on the electrode structure.

[0108] Comparative Example 2

[0109] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, and the high aluminum layer is composed of Al 0.1 Ga 0.9 Made of N;

[0110] Wherein, the high aluminum layer has not been oxidized and has a thickness of 10 nm.

[0111] Comparative Example 3

[0112] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, and the high aluminum layer is composed of Al 0.1 Ga 0.9 Made of N;

[0113] The high aluminum layer is oxidized for 5 minutes and has a thickness of 10 nm.

[0114] Comparative Example 4

[0115] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, and the high aluminum layer is composed of Al 0.2 Ga 0.8 Made of N;

[0116] The high aluminum layer is oxidized for 5 minutes and has a thickness of 10 nm.

[0117] Comparative Example 5

[0118] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al 0.1 Ga 0.9 Made of N;

[0119] The high aluminum layer has not been oxidized, has a thickness of 10 nm, and the size of the through hole is 3*3 μm.

[0120] Comparative Example 6

[0121] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al 0.2 Ga 0.8 Made of N;

[0122] The high aluminum layer has not been oxidized, has a thickness of 10 nm, and the size of the through hole is 3*3 μm.

[0123] Comparative Example 7

[0124] A vertical UV LED chip comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al 0.5 Ga 0.5 Made of N;

[0125] The high aluminum layer has not been oxidized, has a thickness of 10 nm, and the size of the through hole is 3*3 μm.

[0126] Specifically, the chip sizes of Examples 1 to 7 and Comparative Examples 1 to 7 are the same. The chips of Examples 1 to 7 and Comparative Examples 1 to 7 are tested, and the results are as follows:

[0127] project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Voltage (V) 3.65 3.67 3.69 3.75 3.89 3.97 4.2 Brightness(mW) 130 135 135 120 115 110 100

[0128] project Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Voltage (V) 3.56 4.5 5.5 6.6 3.63 3.87 4.57 Brightness(mW) 80 65 30 20 90 100 100

[0129] From the above structure, it can be seen that embodiments 1 to 7 of the present invention effectively improve the brightness of the chip by setting a high aluminum layer. The high aluminum layer of embodiment 7 is thicker and has a larger through-hole size, so the brightness is lower than other embodiments, and the voltage is also higher than other embodiments. Comparative Example 1 is an existing vertical structure, and the high aluminum layer of the present invention is not set, so the brightness is significantly lower than that of embodiments 1 to 7 of the present invention; although Comparative Example 2 is provided with a high aluminum layer, the high aluminum layer is not provided with through holes, and has not been oxidized, its brightness is still lower than that of Comparative Example 1, and the voltage is also significantly increased; although Comparative Examples 3 and 4 are provided with a high aluminum layer and have been oxidized, the high aluminum layer is not provided with through holes, and its brightness is still lower than that of Comparative Example 2, and the voltage is also significantly increased; Comparative Examples 5-7 are provided with a high aluminum layer, and the high aluminum layer is provided with through holes. Although no oxidation treatment is performed, the brightness is higher than that of Comparative Example 1, among which, the high aluminum layer of Comparative Example 7 has a significantly increased voltage due to the excessively high aluminum content.

[0130] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A vertical UV LED chip, characterized in that: The invention comprises a conductive substrate, an epitaxial layer, a high aluminum layer, a transparent conductive layer and an electrode structure, wherein the electrode structure is arranged between the conductive substrate and the transparent conductive layer, the high aluminum layer is arranged between the transparent conductive layer and the epitaxial layer, the high aluminum layer is provided with a plurality of through holes, the through holes are arranged in an array, and the high aluminum layer is composed of Al x Ga 1-x N, x is 0.15-0.45, the transparent conductive layer is filled into the through hole and forms a conductive connection with the epitaxial layer; The high-aluminum layer is subjected to oxidation treatment so that the aluminum on the surface of the high-aluminum layer is oxidized to form aluminum oxide.

2. The vertical UV LED chip according to claim 1, characterized in that: The size of the through hole is (3~10)*(3~10)μm; The thickness of the high aluminum layer is 10-100 nm.

3. The vertical UV LED chip according to claim 2, characterized in that: The high aluminum layer is provided with m rows and n columns of through holes, m≥3, n≥3, wherein the through holes in odd rows are on even columns, and the through holes in even rows are on odd columns.

4. The vertical UV LED chip according to claim 3, characterized in that: The through holes in the odd-numbered rows are correspondingly arranged on the center lines of two adjacent through holes in the even-numbered rows; The distance between through holes in the same row or column is 35~40μm.

5. The vertical UV LED chip according to claim 1, characterized in that: x is 0.2~0.

4.

6. The vertical UV LED chip according to claim 1, characterized in that: The electrode structure includes an Ag layer, a TiW layer and a Pt layer, wherein the Ag layer is disposed between the transparent conductive layer and the TiW layer, and the Pt layer is disposed on the TiW layer.

7. A method for preparing a vertical UV LED chip, characterized in that: The following steps are involved: S1, forming an epitaxial layer on a substrate; S2, forming Al on the epitaxial layer x Ga 1-x A high aluminum layer made of N, x is 0.15-0.45, wherein the high aluminum layer is provided with a plurality of through holes, and the through holes are arranged in an array; S3, performing oxidation treatment on the high aluminum layer to oxidize aluminum on the surface of the high aluminum layer to form aluminum oxide; S4, forming a transparent conductive layer on the high aluminum layer, and filling the transparent conductive layer into the through hole to form a conductive connection with the epitaxial layer; S5, forming an electrode structure on the transparent conductive layer; S6. Remove the substrate and bond the electrode structure to the conductive substrate.

8. The method for preparing a vertical UV LED chip according to claim 7, characterized in that: In step S2, MOCVD is used to introduce TMAl, TMGa, NH3 and N2 at a temperature of 900-1300°C, with flow rates of 250-350 sccm, 10-16 sccm, 30-35 SLM and 70-85 SLM, respectively, to form an Al-based epitaxial layer. x Ga 1-x High aluminum layer made of N.

9. The method for preparing a vertical UV LED chip according to claim 8, characterized in that: In step S2, the high aluminum layer is etched by ICP etching or photolithography until the surface of the epitaxial layer is reached to form a plurality of through holes arranged in an array.

10. The method for preparing a vertical UV LED chip according to claim 7, wherein: In step S3, the high-aluminum layer is placed in an oxidation device, oxygen is introduced, and the device is started to bombard the high-aluminum layer, and the treatment time is 5 to 15 minutes.

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