Deep ultraviolet light emitting diode and epitaxial growth method thereof

Abstract

The application discloses a deep ultraviolet light emitting diode and an epitaxial growth method thereof. The deep ultraviolet light emitting diode comprises, from bottom to top, a substrate, an intrinsic layer, an electron injection layer, a quantum well active layer, an electron blocking layer, a hole injection layer and a P-type contact layer. The deep ultraviolet light emitting diode further comprises a leakage current improvement layer. The leakage current improvement layer is arranged between the electron injection layer and the current expansion layer and / or arranged between the quantum well active layer and the electron blocking layer. The leakage current improvement layer is a non-intentionally doped layer. The leakage current improvement layer can not only reduce the dislocation density of the electron injection layer penetrating into the quantum well active layer, but also block the internal diffusion of silicon elements in the electron injection layer into the quantum well active layer or block the internal diffusion of magnesium elements in the hole injection layer into the quantum well active layer, thereby reducing the reverse leakage current of the deep ultraviolet light emitting diode.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronics, and more particularly to a deep ultraviolet light-emitting diode and its epitaxial growth method. Background Technology

[0002] Currently, light with wavelengths between 200 and 350 nanometers in the ultraviolet spectrum is referred to as deep ultraviolet light. Deep ultraviolet light-emitting diodes (LEDs) possess significant application value in fields such as lighting, sterilization, medical treatment, printing, biochemical detection, high-density information storage, and secure communication due to their advantages of high efficiency, environmental friendliness, energy saving, and reliability—advantages that ordinary ultraviolet LEDs cannot match.

[0003] However, deep ultraviolet (DUV) light-emitting diodes (LEDs) typically exhibit significant leakage current, which increases with chip size. This is primarily due to several factors. First, the epitaxial structure of DUVs utilizes aluminum gallium nitride (AGaN) materials with a high aluminum content. The heteroepitaxial growth of this high-aluminum AGaN material on a sapphire substrate allows numerous dislocations to penetrate into the quantum well active region, leading to leakage. Second, because electrons have a higher electron transport capacity than holes in DUVs, electrons often bypass the electron blocking layer, resulting in electron overflow and leakage. Finally, the epitaxial structure of DUVs is typically grown at high temperatures, causing silicon from the N-type injection layer and magnesium from the P-type injection layer to diffuse into the quantum well active region, further contributing to leakage.

[0004] Therefore, there is an urgent need for a deep ultraviolet light-emitting diode and its epitaxial growth method to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a deep ultraviolet light-emitting diode and its epitaxial growth method, which improves the technical problem of large leakage current in the epitaxial structure of deep ultraviolet light-emitting diodes in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides a deep ultraviolet light-emitting diode, including a substrate, an intrinsic layer disposed on the substrate, an electron injection layer disposed on the intrinsic layer, a current spreading layer disposed on the electron injection layer, a quantum well active layer disposed on the current spreading layer, an electron blocking layer disposed on the quantum well active layer, a hole injection layer disposed on the electron blocking layer, and a P-type contact layer disposed on the hole injection layer.

[0007] The deep ultraviolet light-emitting diode also includes a leakage current improvement layer, which is disposed between the electron injection layer and the current spreading layer and / or between the quantum well active layer and the electron blocking layer; the leakage current improvement layer is an unintentionally doped layer.

[0008] In the deep ultraviolet light-emitting diode provided in the embodiments of the present invention, the leakage current improvement layer includes a first improvement layer, which is disposed between the electron injection layer and the current spreading layer;

[0009] The first improvement layer is a first superlattice structure formed by alternating first sublayers and second sublayers. The first sublayer uses aluminum nitride as the growth material, and the second sublayer uses gallium nitride as the growth material.

[0010] In the deep ultraviolet light-emitting diode provided in the embodiments of the present invention, the deep ultraviolet light-emitting diode further includes an N-type electrode and a P-type electrode;

[0011] In this structure, a stepped structure is formed between the first improvement layer and the current spreading layer, and the area of ​​the first improvement layer is larger than the area of ​​the current spreading layer. The P-type electrode is disposed on the P-type contact layer, and the N-type electrode is disposed at the stepped structure of the first improvement layer.

[0012] In the deep ultraviolet light-emitting diode provided in the embodiments of the present invention, in the first superlattice structure, the thickness of the first sublayer ranges from 0.1 nm to 5 nm, and the thickness of the second sublayer ranges from 0.2 nm to 6 nm; the superlattice period of the first superlattice structure ranges from 2 to 20.

[0013] In the deep ultraviolet light-emitting diode provided in the embodiments of the present invention, the difference between the growth temperature of the first sublayer and the growth temperature of the second sublayer is between 20°C and 100°C; the intermediate temperature change time between the first sublayer and the second sublayer is between 20s and 200s.

[0014] In the deep ultraviolet light-emitting diode provided in the embodiments of the present invention, the leakage current improvement layer further includes a second improvement layer, which is disposed between the quantum well active layer and the electron blocking layer.

[0015] The second improvement layer is a second superlattice structure formed by alternating third and fourth sublayers, and the third sublayer is made of Al. a Ga 1-a Nitrogen (N) was used as the growth material, and Al was used for the fourth sublayer. b Ga 1-b N is used as the growth material, the third sublayer is in contact with the quantum well active layer, and the fourth sublayer is in contact with the electron blocking layer;

[0016] In the active layer of the quantum well, the proportion of Al component of the quantum barrier is x, and the relationship between a, b and x satisfies 40%≤b≤x≤a≤100% and 5%≤ab≤30%.

[0017] In the deep ultraviolet light-emitting diode provided in the embodiments of the present invention, in the second superlattice structure, the thickness of the third sublayer ranges from 0.1 nm to 20 nm, and the thickness of the fourth sublayer ranges from 0.1 nm to 20 nm; the superlattice period of the second superlattice structure ranges from 1 to 50.

[0018] This invention also proposes an epitaxial growth method for deep ultraviolet light-emitting diodes, the method comprising:

[0019] An intrinsic layer is epitaxially grown on a substrate;

[0020] An electron-injected layer is epitaxially grown on the intrinsic layer;

[0021] A quantum well active layer is epitaxially grown on the electron injection layer;

[0022] An electron blocking layer is epitaxially grown on the active layer of a quantum well;

[0023] Epitaxial growth of a hole injection layer on an electron blocking layer;

[0024] An n-type contact layer is epitaxially grown on the hole injection layer;

[0025] The deep ultraviolet light-emitting diode also includes a leakage current improvement layer, which is disposed between the electron injection layer and the current spreading layer, and / or, the leakage current improvement layer is disposed between the quantum well active layer and the electron blocking layer; the leakage current improvement layer is an unintentionally doped layer.

[0026] In the epitaxial growth method for deep ultraviolet light-emitting diodes provided in this embodiment of the invention, the step of epitaxially growing an electron injection layer on the intrinsic layer further includes:

[0027] A first improvement layer is epitaxially grown on the electron injection layer. The first improvement layer is a first superlattice structure formed by alternating multiple first sublayers and multiple second sublayers. The first sublayer uses aluminum nitride as the growth material, and the second sublayer uses gallium nitride as the growth material.

[0028] The difference between the growth temperature of the first sublayer and the growth temperature of the second sublayer ranges from 20℃ to 100℃; the intermediate temperature change time between the first and second sublayers ranges from 20s to 200s.

[0029] In the epitaxial growth method of deep ultraviolet light-emitting diode provided in the embodiments of the present invention, when the intermediate temperature change time between the first sublayer and the second sublayer is between 50s and 200s, after the second sublayer is epitaxially grown on the electron injection layer, a capping layer is epitaxially grown on the second sublayer at a first temperature, and the first sublayer is epitaxially grown on the capping layer at a second temperature.

[0030] The thickness of the capping layer ranges from 0.1 nm to 1 nm, the second temperature is greater than the first temperature, and the material of the capping layer is the same as that of the first sublayer.

[0031] The beneficial effects of this invention are as follows: Unlike the prior art, this invention provides a leakage current improvement layer between the electron injection layer and the current spreading layer, and / or between the quantum well active layer and the electron blocking layer. The leakage current improvement layer between the electron injection layer and the current spreading layer reduces the dislocation density penetrating from the electron injection layer to the quantum well active layer and blocks the internal diffusion of silicon elements in the electron injection layer into the quantum well active layer, thereby reducing the reverse leakage current of the deep ultraviolet light-emitting diode. The leakage current improvement layer between the quantum well active layer and the electron blocking layer blocks the internal diffusion of magnesium elements in the hole injection layer into the quantum well active layer, ultimately reducing the reverse leakage current of the deep ultraviolet light-emitting diode. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the first structure of the deep ultraviolet light-emitting diode provided in the embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the second structure of the deep ultraviolet light-emitting diode provided in the embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the third structure of the deep ultraviolet light-emitting diode provided in the embodiments of the present invention;

[0035] Figure 4 This is a process flow diagram of the epitaxial growth method for deep ultraviolet light-emitting diodes provided in an embodiment of the present invention. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] Please see Figures 1 to 3 This invention provides a deep ultraviolet light-emitting diode 100, including a substrate 11, an intrinsic layer 12 disposed on the substrate 11, an electron injection layer 13 disposed on the intrinsic layer 12, a current spreading layer 15 disposed on the electron injection layer 13, a quantum well active layer 16 disposed on the current spreading layer 15, an electron blocking layer 17 disposed on the quantum well active layer 16, a hole injection layer 18 disposed on the electron blocking layer 17, and a P-type contact layer 19 disposed on the hole injection layer 18.

[0038] In this embodiment, the deep ultraviolet light-emitting diode 100 further includes a leakage current improvement layer 14, which is disposed between the electron injection layer 13 and the current spreading layer 15 and / or between the quantum well active layer 16 and the electron blocking layer 17; the leakage current improvement layer 14 is an unintentionally doped layer.

[0039] In this embodiment of the invention, a leakage current improvement layer 14 is provided between the electron injection layer 13 and the current spreading layer 15 and / or between the quantum well active layer 16 and the electron blocking layer 17. The leakage current improvement layer 14 provided between the electron injection layer 13 and the current spreading layer 15 can reduce the dislocation density penetrating from the electron injection layer 13 to the quantum well active layer 16 and can block the internal diffusion of silicon elements in the electron injection layer 13 to the quantum well active layer 16, thereby reducing the reverse leakage current of the deep ultraviolet light-emitting diode 100. And / or, the leakage current improvement layer 14 provided between the quantum well active layer 16 and the electron blocking layer 17 can block the internal diffusion of magnesium elements in the hole injection layer 18 to the quantum well active layer 16, ultimately reducing the reverse leakage current of the deep ultraviolet light-emitting diode 100.

[0040] The technical solution of this application will now be described in conjunction with specific embodiments.

[0041] Example 1

[0042] Please see Figure 1 , Figure 1 This is a schematic diagram of a first structure of a deep ultraviolet light-emitting diode 100 provided in an embodiment of the present invention; wherein, the deep ultraviolet light-emitting diode 100 includes a substrate 11, an intrinsic layer 12 disposed on the substrate 11, an electron injection layer 13 disposed on the intrinsic layer 12, a current spreading layer 15 disposed on the electron injection layer 13, a quantum well active layer 16 disposed on the current spreading layer 15, an electron blocking layer 17 disposed on the quantum well active layer 16, a hole injection layer 18 disposed on the electron blocking layer 17, and a P-type contact layer 19 disposed on the hole injection layer 18;

[0043] In this embodiment of the invention, the deep ultraviolet light-emitting diode 100 further includes a leakage current improvement layer 14, which is disposed between the electron injection layer 13 and the current spreading layer 15. The leakage current improvement layer 14 is an unintentionally doped layer. The unintentionally doped layer is a type of contaminating impurity, and is not a doped material that is artificially introduced as a donor or acceptor.

[0044] In this embodiment of the invention, substrate 11 is a sapphire substrate. Sapphire substrates have many advantages: firstly, the production technology of sapphire substrates is mature, and the device quality is good; secondly, sapphire has excellent stability and can be used in high-temperature growth processes; finally, sapphire has high mechanical strength and is easy to handle and clean. Therefore, most processes generally use sapphire as a substrate.

[0045] In this embodiment of the invention, the intrinsic layer 12 includes a low-temperature buffer layer disposed on the substrate 11 and an aluminum nitride intrinsic layer disposed on the low-temperature buffer layer; wherein, the material of the low-temperature buffer layer is aluminum nitride, the growth temperature ranges from 400°C to 800°C, and the thickness ranges from 10nm to 50nm; the material of the aluminum nitride intrinsic layer 12 is aluminum nitride, the growth temperature ranges from 1200°C to 1400°C, and the thickness ranges from 500nm to 4000nm.

[0046] In this embodiment of the invention, the electron injection layer 13 is made of N-type doped aluminum gallium nitride material; wherein the aluminum content ranges from 20% to 90%, the thickness of the electron injection layer 13 ranges from 500 nm to 4000 nm, and the growth temperature of the electron injection layer 13 ranges from 800 °C to 1200 °C.

[0047] In an embodiment of the present invention, the leakage current improvement layer 14 includes a first improvement layer 141, which is disposed on the electron injection layer 13.

[0048] The first improvement layer 141 is a first superlattice structure formed by alternating first sublayers and second sublayers. The first sublayer uses aluminum nitride as the growth material, and the second sublayer uses gallium nitride as the growth material.

[0049] Specifically, the growth temperature of the first improvement layer 141 is between 800°C and 1200°C; the difference between the growth temperature of the first sublayer and the growth temperature of the second sublayer is between 20°C and 100°C; and the intermediate temperature change time between the first sublayer and the second sublayer is between 20s and 200s.

[0050] Furthermore, if the intermediate temperature change time between the first sublayer and the second sublayer exceeds 50 seconds, after the second sublayer is epitaxially grown on the electron injection layer 13, a capping layer is epitaxially grown on the second sublayer at the first temperature, and the first sublayer is epitaxially grown on the capping layer at the second temperature.

[0051] The thickness of the capping layer ranges from 0.1 nm to 1 nm, the second temperature is greater than the first temperature, and the material of the capping layer is the same as that of the first sublayer.

[0052] In this embodiment of the invention, in the first superlattice structure, the thickness of the first sublayer ranges from 0.1 nm to 5 nm, and the thickness of the second sublayer ranges from 0.2 nm to 6 nm; the superlattice period of the first superlattice structure ranges from 2 to 20.

[0053] In this embodiment of the invention, the current spreading layer 15 is disposed on the first improvement layer 141, and the quantum well active layer 16 is disposed on the current spreading layer 15; wherein, the growth temperature range of the current spreading layer 15 and the quantum well active layer 16 is between 700°C and 1100°C.

[0054] Specifically, the material of the current spreading layer 15 is aluminum gallium nitride, the percentage of aluminum in the current spreading layer 15 is between 20% and 90%, and the thickness of the current spreading layer 15 is between 10 nm and 300 nm.

[0055] Specifically, the barrier thickness of the quantum well active layer 16 ranges from 5 nm to 30 nm, and the percentage of aluminum in the barrier ranges from 20% to 100%; the well thickness of the quantum well active layer 16 ranges from 0.1 to 5 nm; and the percentage of aluminum in the well ranges from 0% to 80%.

[0056] Specifically, a stepped structure is formed between the first improvement layer 141 and the current extension layer 15, and the area of ​​the first improvement layer 141 is larger than the area of ​​the current extension layer 15.

[0057] In this embodiment of the invention, an electron blocking layer 17 is disposed on the quantum well active layer 16, and the growth temperature of the electron blocking layer 17 is between 700°C and 1100°C; wherein, the electron blocking layer 17 is a single-layer AlGaN structure, or, the electron blocking layer 17 is a third superlattice structure formed by alternating fifth sublayers and sixth sublayers, wherein the fifth sublayer is made of Al c Ga 1-c Nitrogen (N) was used as the growth material, and Al was used for the sixth sublayer. d Ga 1-d N is used as the growth material, where 0 < c ≤ d < 1.

[0058] Among them, the electron blocking layer 17 is a p-type doped semiconductor material, which uses Mg as a p-type dopant.

[0059] Furthermore, the percentage of aluminum in the electron blocking layer 17 ranges from 50% to 80%, and the thickness of the electron blocking layer 17 ranges from 0.1 nm to 200 nm.

[0060] In this embodiment of the invention, a hole injection layer 18 is disposed on an electron blocking layer 17, and the growth temperature of the hole injection layer 18 is between 700°C and 1100°C. The hole injection layer 18 is made of p-type doped aluminum gallium nitride, the percentage of aluminum in the hole injection layer 18 is between 0% and 100%, the thickness of the hole injection layer 18 is between 1 nm and 50 nm, and magnesium is used as a p-type dopant in the hole injection layer 18.

[0061] In this embodiment of the invention, a P-type contact layer 19 is disposed on a hole injection layer 18, and the growth temperature of the P-type contact layer 19 is between 400°C and 900°C; wherein, the material of the P-type contact layer 19 is P-type doped gallium nitride, the thickness of the P-type contact layer 19 is between 1 nm and 20 nm, and magnesium is used as the P-type dopant in the P-type contact layer 19.

[0062] In this embodiment of the invention, the deep ultraviolet light-emitting diode 100 further includes an N-type electrode and a P-type electrode; wherein, a stepped structure is formed between the first improvement layer 141 and the current spreading layer 15, and the area of ​​the first improvement layer 141 is larger than the area of ​​the current spreading layer 15, the P-type electrode is disposed on the P-type contact layer 19, and the N-type electrode is disposed at the stepped structure of the first improvement layer 141.

[0063] Unlike existing technologies, in Embodiment 1 of the present invention, a leakage current improvement layer 14 is provided between the electron injection layer 13 and the current spreading layer 15. The leakage current improvement layer 14 provided between the electron injection layer 13 and the current spreading layer 15 can reduce the dislocation density penetrating from the electron injection layer 13 to the quantum well active layer 16, and can block the internal diffusion of silicon elements in the electron injection layer 13 to the quantum well active layer 16, thereby reducing the reverse leakage current of the deep ultraviolet light-emitting diode 100.

[0064] Example 2

[0065] Please see Figure 2 , Figure 2 This is a schematic diagram of a second structure of a deep ultraviolet light-emitting diode 100 provided in an embodiment of the present invention. The structure of the deep ultraviolet light-emitting diode 100 provided in the second embodiment of the present invention is the same as or similar to the structure of the deep ultraviolet light-emitting diode 100 provided in the first embodiment of the present invention. The only difference is that the leakage current improvement layer 14 includes a second improvement layer 142 and does not include a first improvement layer 141. The second improvement layer 142 is only disposed between the quantum well active layer 16 and the electron blocking layer 17. The second improvement layer 142 is an unintentionally doped layer.

[0066] Specifically, the second improvement layer 142 is a second superlattice structure formed by alternating third and fourth sublayers, with the third sublayers using Al. a Ga1-a Nitrogen (N) was used as the growth material, and Al was used for the fourth sublayer. b Ga 1-b N is used as the growth material. The third sublayer is in contact with the quantum well active layer 16, and the fourth sublayer is in contact with the electron blocking layer 17.

[0067] Among them, the Al composition ratio of the quantum barrier (aluminum gallium nitride) in the active layer 16 of the quantum well is x, and the relationship between a, b and x satisfies 40%≤b≤x≤a≤100% and 5%≤ab≤30%.

[0068] Furthermore, in the second superlattice structure, the thickness of the third sublayer ranges from 0.1 nm to 20 nm, and the thickness of the fourth sublayer ranges from 0.1 nm to 20 nm; the superlattice period of the second superlattice structure ranges from 1 to 50.

[0069] Since the electron blocking layer 17 is a P-type doped semiconductor structure, the magnesium element in the electron blocking layer 17 can easily diffuse into the interior of the quantum well active layer 16; therefore, the second improvement layer 142 can also block the diffusion of the magnesium element in the electron blocking layer 17 into the interior of the quantum well active layer 16.

[0070] Compared with Embodiment 1, Embodiment 2 of the present invention reduces the reverse leakage current of the deep ultraviolet light-emitting diode 100 by placing the leakage current improvement layer 14 between the quantum well active layer 16 and the electron blocking layer 17 to block the diffusion of magnesium element in the hole injection layer 18 into the quantum well active layer 16.

[0071] Example 3

[0072] Please see Figure 3 , Figure 3 This is a schematic diagram of a third structure of a deep ultraviolet light-emitting diode 100 provided in an embodiment of the present invention. The structure of the deep ultraviolet light-emitting diode 100 provided in the third embodiment of the present invention is the same as or similar to the structure of the deep ultraviolet light-emitting diode 100 provided in the first embodiment of the present invention. The only difference is that the leakage current improvement layer 14 includes a first improvement layer 141 and a second improvement layer 142. The first improvement layer 141 is disposed between the electron injection layer 13 and the current spreading layer 15, and the second improvement layer 142 is disposed between the quantum well active layer 16 and the electron blocking layer 17. Both the first improvement layer 141 and the second improvement layer 142 are unintentionally doped layers.

[0073] Compared to Embodiment 1, Embodiment 3 of the present invention provides a first improvement layer 141 between the electron injection layer 13 and the current spreading layer 15. The first improvement layer 141 can reduce the dislocation density penetrating from the electron injection layer 13 to the quantum well active layer 16 and can block the internal diffusion of silicon elements in the electron injection layer 13 to the quantum well active layer 16, thereby reducing the reverse leakage current of the deep ultraviolet light-emitting diode 100. At the same time, the second improvement layer 142 disposed between the quantum well active layer 16 and the electron blocking layer 17 can block the internal diffusion of magnesium elements in the hole injection layer 18 to the quantum well active layer 16, ultimately reducing the reverse leakage current of the deep ultraviolet light-emitting diode 100.

[0074] Compared with Embodiment 1 or Embodiment 2 of the present invention, Embodiment 3 of the present invention makes it easier to reduce the reverse leakage current of the deep ultraviolet light-emitting diode 100.

[0075] Accordingly, embodiments of the present invention also provide an epitaxial growth method for a deep ultraviolet light-emitting diode 100; please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a process flow diagram of the epitaxial growth method for the deep ultraviolet light-emitting diode 100 provided in an embodiment of the present invention. Specifically, taking the preparation of Embodiment 3 of the present invention as an example, the epitaxial growth method includes:

[0076] S10, an intrinsic layer 12 is epitaxially grown on a substrate 11.

[0077] Specifically, S10 also includes:

[0078] First, a substrate 11 is provided, wherein the substrate 11 is a sapphire substrate 11. Then, a buffer layer is grown on the substrate 11 at a low temperature of 400℃ to 800℃, the thickness of the buffer layer ranging from 10nm to 50nm. Finally, the growth temperature is raised to between 1200℃ and 1400℃, and an intrinsic aluminum nitride layer 12 is grown on the buffer layer, the thickness of the intrinsic aluminum nitride layer 12 ranging from 500nm to 4000nm. The buffer layer and the intrinsic aluminum nitride layer 12 constitute the intrinsic layer 12, and both the buffer layer and the intrinsic aluminum nitride layer 12 are made of aluminum nitride.

[0079] S20, an electron injection layer 13 is epitaxially grown on intrinsic layer 12.

[0080] Specifically, S20 also includes:

[0081] First, the growth temperature is lowered to between 800°C and 1200°C; then, an electron injection layer 13 is epitaxially grown on the intrinsic layer 12. The electron injection layer 13 is made of N-type doped aluminum gallium nitride, with the aluminum content ranging from 20% to 90%.

[0082] S30, a quantum well active layer 16 is epitaxially grown on the electron injection layer 13.

[0083] Specifically, S30 also includes:

[0084] First, the growth temperature is maintained between 800°C and 1200°C, and a first improvement layer 141 is epitaxially grown on the electron injection layer 13. The first improvement layer 141 is a first superlattice structure formed by alternating first sublayers and second sublayers. The first sublayers use aluminum nitride as the growth material, and the second sublayers use gallium nitride as the growth material.

[0085] Specifically, the difference between the growth temperature of the first sublayer and the growth temperature of the second sublayer ranges from 20°C to 100°C; the intermediate temperature change time between the first and second sublayers ranges from 20s to 200s.

[0086] Furthermore, if the intermediate temperature change time between the first sublayer and the second sublayer exceeds 50 seconds, after the second sublayer is epitaxially grown on the electron injection layer 13, a capping layer is epitaxially grown on the second sublayer at a first temperature, and the first sublayer is epitaxially grown on the capping layer at a second temperature; wherein, the thickness of the capping layer is between 0.1 nm and 1 nm, the value of the second temperature is greater than the value of the first temperature, and the material of the capping layer is the same as the material of the first sublayer.

[0087] In this embodiment of the invention, in the first superlattice structure, the thickness of the first sublayer ranges from 0.1 nm to 5 nm, and the thickness of the second sublayer ranges from 0.2 nm to 6 nm; the superlattice period of the first superlattice structure ranges from 2 to 20.

[0088] Subsequently, the growth temperature is lowered to between 700°C and 1100°C, and a current extension layer 15 and a quantum well active layer 16 are epitaxially grown sequentially on the first improvement layer 141. The barrier thickness of the quantum well active layer 16 is between 5 and 30 nm, and the percentage of aluminum composition in the barrier is between 20% and 100%. The well thickness of the quantum well active layer 16 is between 0.1 and 5 nm, and the percentage of aluminum composition in the well is between 0 and 80%.

[0089] Specifically, the material of the current spreading layer 15 is aluminum gallium nitride, the percentage of aluminum in the current spreading layer 15 is between 20% and 90%, and the thickness of the current spreading layer 15 is between 10 nm and 300 nm.

[0090] Specifically, a stepped structure is formed between the first improvement layer 141 and the current extension layer 15, and the area of ​​the first improvement layer 141 is larger than the area of ​​the current extension layer 15.

[0091] S40, an electron blocking layer 17 is epitaxially grown on the active layer 16 of the quantum well.

[0092] Specifically, S40 also includes:

[0093] First, maintaining the growth temperature range between 700℃ and 1100℃, a second improvement layer 142 is epitaxially grown on the quantum well active layer 16. Specifically, the second improvement layer 142 is a second superlattice structure formed by alternating third and fourth sublayers, with the third sublayers using Al. a Ga 1-a Nitrogen (N) was used as the growth material, and Al was used for the fourth sublayer. b Ga 1-b N is used as the growth material. The third sublayer is in contact with the quantum well active layer 16, and the fourth sublayer is in contact with the electron blocking layer 17.

[0094] The quantum barrier is defined as x, and the relationship between a, b and x satisfies 40% ≤ b ≤ x ≤ a ≤ 100% and 5% ≤ ab ≤ 30%.

[0095] Furthermore, in the second superlattice structure, the thickness of the third sublayer ranges from 0.1 nm to 20 nm, and the thickness of the fourth sublayer ranges from 0.1 nm to 20 nm; the superlattice period of the second superlattice structure ranges from 1 to 50.

[0096] Subsequently, the growth temperature is maintained between 700°C and 1100°C, and an electron blocking layer 17 is epitaxially grown on the second improved layer 142. The electron blocking layer 17 is a monolayer AlGaN structure, or it is a third superlattice structure formed by alternating fifth and sixth sublayers, with the fifth sublayers using Al... c Ga 1-c Nitrogen (N) was used as the growth material, and Al was used for the sixth sublayer. d Ga 1-d N is used as the growth material, where 0 < c ≤ d < 1.

[0097] Among them, the electron blocking layer 17 is a p-type doped semiconductor material, which uses Mg as a p-type dopant.

[0098] Furthermore, the percentage of aluminum in the electron blocking layer 17 ranges from 50% to 80%, and the thickness of the electron blocking layer 17 ranges from 0.1 nm to 200 nm.

[0099] S50, a hole injection layer 18 is epitaxially grown on the electron blocking layer 17.

[0100] Specifically, the S50 also includes:

[0101] The growth temperature is maintained between 700℃ and 1100℃, and a hole injection layer 18 is epitaxially grown on the electron blocking layer 17. The hole injection layer 18 is made of p-type doped aluminum gallium nitride, the percentage of aluminum in the hole injection layer 18 ranges from 0% to 100%, the thickness of the hole injection layer 18 ranges from 1nm to 50nm, and magnesium is used as the p-type dopant in the hole injection layer 18.

[0102] S60, a P-type contact layer 19 is epitaxially grown on the hole injection layer 18.

[0103] Specifically, the S60 also includes:

[0104] First, the growth temperature is lowered to between 400°C and 900°C to form a P-type contact layer 19 on the hole injection layer 18. The material of the P-type contact layer 19 is P-type doped gallium nitride, the thickness of the P-type contact layer 19 is between 1 nm and 20 nm, and magnesium is used as the P-type dopant in the P-type contact layer 19.

[0105] Next, an N-type electrode is provided at the stepped structure of the first improvement layer 141, with the N-type electrode opposite to and spaced apart from the current extension layer 15; finally, a P-type electrode is formed on the P-type contact layer 19.

[0106] Specifically, four different deep ultraviolet light-emitting diodes 100 were fabricated using the epitaxial growth method described above. After the deep ultraviolet light-emitting diodes 100 were fabricated, the reverse leakage current of each deep ultraviolet light-emitting diode 100 was tested under a reverse voltage of 5V.

[0107] Furthermore, the film structure of the above four different deep ultraviolet light-emitting diodes 100, from bottom to top, from the substrate 11 to the P-type electrode, is shown below:

[0108] Example 1:

[0109] The deep ultraviolet light-emitting diode 100 (deep ultraviolet LED 1) provided in the first embodiment of this application includes:

[0110] Substrate 11 is a sapphire substrate 11;

[0111] Intrinsic layer 12 is aluminum nitride with a thickness of 1000 nm;

[0112] The electron injection layer 13 is an N-type doped aluminum gallium nitride material, wherein the Al component in the electron injection layer 13 accounts for 50% of the mass percentage of the electron injection layer 13 and has a thickness of 1000 nm.

[0113] The first improvement layer 141 is a first superlattice structure formed by alternating first sublayers and second sublayers. The first sublayers use aluminum nitride as the growth material, and the second sublayers use gallium nitride as the growth material. The thickness of the first sublayer is 0.5 nm, and the thickness of the second sublayer is 1 nm. The number of superlattice periods of the first superlattice structure is 10.

[0114] The material of the current spreading layer 15 is AlGaN, wherein the Al component accounts for 70% of the mass percentage of the current spreading layer 15 and the thickness is 100nm.

[0115] The active layer 16 of the quantum well has a quantum well thickness of 1 nm and an Al component mass percentage of 50% in the quantum well, and a quantum barrier thickness of 2 nm and an Al component percentage of 60% in the barrier.

[0116] The electron blocking layer 17 is a single-layer AlGaN structure with a thickness of 10 nm and an Al composition of 40% by mass.

[0117] The hole injection layer 18 is made of p-type doped aluminum gallium nitride. The mass percentage of aluminum in the hole injection layer 18 is 40%, the thickness is 20 nm, and Mg is used as the p-type dopant.

[0118] The material of the P-type contact layer 19 is P-type doped gallium nitride, and the thickness of the P-type contact layer 19 is 10 nm. Mg is used as the p-type dopant.

[0119] Example 2:

[0120] The deep ultraviolet light-emitting diode 100 (deep ultraviolet LED2) provided in the second embodiment of this application includes:

[0121] Substrate 11 is a sapphire substrate 11;

[0122] Intrinsic layer 12 is aluminum nitride with a thickness of 1000 nm;

[0123] The electron injection layer 13 is an N-type doped aluminum gallium nitride material, wherein the Al component in the electron injection layer 13 accounts for 50% of the mass percentage of the electron injection layer 13 and has a thickness of 1000 nm.

[0124] The material of the current spreading layer 15 is AlGaN, wherein the Al component accounts for 70% of the mass percentage of the current spreading layer 15 and the thickness is 100nm.

[0125] The active layer 16 of the quantum well has a quantum well thickness of 1 nm and an Al component mass percentage of 50% in the quantum well, and a quantum barrier thickness of 2 nm and an Al component percentage of 60% in the barrier.

[0126] The second improvement layer 142 is a second superlattice structure formed by alternating third and fourth sublayers, wherein the third sublayer is made of Al. a Ga 1-a Nitrogen (N) was used as the growth material, and Al was used for the fourth sublayer. b Ga 1-b N is used as the growth material. The third sublayer is in contact with the quantum well active layer 16, and the fourth sublayer is in contact with the electron blocking layer 17.

[0127] Where a = 0.65, b = 0.45, the thickness of the third sublayer is between 1 nm and the thickness of the fourth sublayer is 1 nm; the number of superlattice periods of the second superlattice structure is 10;

[0128] The electron blocking layer 17 is a single-layer AlGaN structure with a thickness of 10 nm and an Al composition of 40% by mass.

[0129] The hole injection layer 18 is made of p-type doped aluminum gallium nitride. The mass percentage of aluminum in the hole injection layer 18 is 40%, the thickness is 20 nm, and Mg is used as the p-type dopant.

[0130] The P-type contact layer 19 is made of P-type doped gallium nitride, and its thickness is 10 nm. Mg is used as the p-type dopant.

[0131] Example 3:

[0132] The deep ultraviolet light-emitting diode 100 (deep ultraviolet LED3) provided in the third embodiment of the present invention includes:

[0133] Substrate 11 is a sapphire substrate 11;

[0134] Intrinsic layer 12 is aluminum nitride with a thickness of 1000 nm;

[0135] The electron injection layer 13 is an N-type doped aluminum gallium nitride material, wherein the Al component in the electron injection layer 13 accounts for 50% of the mass percentage of the electron injection layer 13 and has a thickness of 1000 nm.

[0136] The first improvement layer 141 is a first superlattice structure formed by alternating first sublayers and second sublayers. The first sublayers use aluminum nitride as the growth material, and the second sublayers use gallium nitride as the growth material. The thickness of the first sublayer is 0.5 nm, and the thickness of the second sublayer is 1 nm. The number of superlattice periods of the first superlattice structure is 10.

[0137] The material of the current spreading layer 15 is AlGaN, wherein the Al component accounts for 70% of the mass percentage of the current spreading layer 15 and the thickness is 100nm.

[0138] The active layer 16 of the quantum well has a quantum well thickness of 1 nm and an Al component mass percentage of 50% in the quantum well, and a quantum barrier thickness of 2 nm and an Al component percentage of 60% in the barrier.

[0139] The second improvement layer 142 is a second superlattice structure formed by alternating third and fourth sublayers, wherein the third sublayer is made of Al. a Ga 1-a Nitrogen (N) was used as the growth material, and Al was used for the fourth sublayer. b Ga 1-b N is used as the growth material. The third sublayer is in contact with the quantum well active layer 16, and the fourth sublayer is in contact with the electron blocking layer 17.

[0140] Where a = 0.65, b = 0.45, the thickness of the third sublayer is between 1 nm and 1 nm, the thickness of the fourth sublayer is 1 nm, and the number of superlattice periods of the second superlattice structure is 10;

[0141] The electron blocking layer 17 is a single-layer AlGaN structure with a thickness of 10 nm and an Al composition of 40% by mass.

[0142] The hole injection layer 18 is made of p-type doped aluminum gallium nitride. The mass percentage of aluminum in the hole injection layer 18 is 40%, the thickness is 20 nm, and Mg is used as the p-type dopant.

[0143] The material of the P-type contact layer 19 is P-type doped gallium nitride, and the thickness of the P-type contact layer 19 is 10 nm. Mg is used as the p-type dopant.

[0144] Comparative Example 1:

[0145] The present invention also provides a comparative embodiment 1, which compares the experimental results with those of the above embodiments. The deep ultraviolet light-emitting diode 100 (deep ultraviolet LED 4) provided in comparative embodiment 1 of the present invention includes:

[0146] Substrate 11 is a sapphire substrate 11;

[0147] Intrinsic layer 12 is aluminum nitride with a thickness of 1000 nm;

[0148] The electron injection layer 13 is an N-type doped aluminum gallium nitride material, wherein the Al component in the electron injection layer 13 accounts for 50% of the mass percentage of the electron injection layer 13 and has a thickness of 1000 nm.

[0149] The material of the current spreading layer 15 is AlGaN, wherein the Al component accounts for 70% of the mass percentage of the current spreading layer 15 and the thickness is 100nm.

[0150] The active layer 16 of the quantum well has a quantum well thickness of 1 nm and an Al component mass percentage of 50% in the quantum well, and a quantum barrier thickness of 2 nm and an Al component percentage of 60% in the barrier.

[0151] The second improvement layer 142 is a second superlattice structure formed by alternating third and fourth sublayers, wherein the third sublayer is made of Al. a Ga 1-a Nitrogen (N) was used as the growth material, and Al was used for the fourth sublayer. b Ga 1-b N is used as the growth material. The third sublayer is in contact with the quantum well active layer 16, and the fourth sublayer is in contact with the electron blocking layer 17.

[0152] Where a = 0.65, b = 0.45, the thickness of the third sublayer is between 1 nm and 1 nm, the thickness of the fourth sublayer is 1 nm, and the number of superlattice periods of the second superlattice structure is 10;

[0153] The electron blocking layer 17 is a single-layer AlGaN structure with a thickness of 10 nm and an Al composition of 40% by mass.

[0154] The hole injection layer 18 is made of p-type doped aluminum gallium nitride. The mass percentage of aluminum in the hole injection layer 18 is 40%, the thickness is 20 nm, and Mg is used as the p-type dopant.

[0155] The material of the P-type contact layer 19 is P-type doped gallium nitride, and the thickness of the P-type contact layer 19 is 10 nm. Mg is used as the p-type dopant.

[0156] In the four deep ultraviolet light-emitting diodes 100 described above, N-type electrodes 110 of the same material are disposed on the electron injection layer using conventional methods, and P-type electrodes 111 of the same material are disposed on the P-type contact layer 19 to form a complete epitaxial chip structure. The specific process is not described in detail here. Among them, both the N-type electrode 110 and the P-type electrode 111 are multilayer composite metal materials.

[0157] Finally, the reverse leakage current of the four deep ultraviolet light-emitting diodes under a reverse voltage of 5V was tested, and the experimental results are shown in Table 1:

[0158] sample Reverse leakage current (uA) Example 1 0.011 Example 2 0.012 Example 3 0.003 Comparative Example 1 0.026

[0159] Table 1

[0160] As shown in Table 1 above, comparing Example 1 or Example 2 with Comparative Example 1, the deep ultraviolet light-emitting diode 100 provided in Example 1 or Example 2 has a relatively low reverse leakage current compared to Comparative Example 1; comparing Example 3 with Example 1 and Example 2, the deep ultraviolet light-emitting diode 100 provided in Example 3 has an even lower reverse leakage current compared to Example 1 and Example 2.

[0161] In summary, unlike the prior art, this embodiment of the invention provides a leakage current improvement layer 14 between the electron injection layer 13 and the current spreading layer 15 and / or between the quantum well active layer 16 and the electron blocking layer 17. The leakage current improvement layer 14 between the electron injection layer 13 and the current spreading layer 15 can reduce the dislocation density penetrating from the electron injection layer 13 to the quantum well active layer 16 and can block the internal diffusion of silicon elements in the electron injection layer 13 to the quantum well active layer 16, thereby reducing the reverse leakage current of the deep ultraviolet light-emitting diode 100. And / or, the leakage current improvement layer 14 between the quantum well active layer 16 and the electron blocking layer 17 can block the internal diffusion of magnesium elements in the hole injection layer 18 to the quantum well active layer 16, ultimately reducing the reverse leakage current of the deep ultraviolet light-emitting diode 100.

[0162] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0163] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A deep ultraviolet light-emitting diode, characterized in that, Including substrates stacked from bottom to top, Intrinsic layer, electron injection layer, current spread layer, quantum well active layer, electron blocking layer, hole injection layer, and P-type contact layer; The deep ultraviolet light-emitting diode further includes a leakage current improvement layer, which is an unintentionally doped layer; The leakage current improvement layer includes a first improvement layer disposed between the electron injection layer and the current spreading layer. The first improvement layer is a first superlattice structure formed by alternating first sub-layers and second sub-layers. The first sub-layers use aluminum nitride as the growth material, and the second sub-layers use gallium nitride as the growth material. The deep ultraviolet light-emitting diode also includes an N-type electrode and a P-type electrode. A stepped structure is formed between the first improvement layer and the current spreading layer, and the area of ​​the first improvement layer is larger than the area of ​​the current spreading layer. The P-type electrode is disposed on the P-type contact layer, and the N-type electrode is disposed at the stepped structure of the first improvement layer.

2. The deep ultraviolet light-emitting diode according to claim 1, characterized in that, In the first superlattice structure, the thickness of the first sublayer ranges from 0.1 nm to 5 nm, and the thickness of the second sublayer ranges from 0.2 nm to 6 nm; the superlattice period of the first superlattice structure ranges from 2 to 20.

3. The deep ultraviolet light-emitting diode according to claim 2, characterized in that, The difference between the growth temperature of the first sublayer and the growth temperature of the second sublayer is between 20°C and 100°C; the intermediate temperature change time between the first sublayer and the second sublayer is between 20s and 200s.

4. The deep ultraviolet light-emitting diode according to claim 1, characterized in that, The leakage current improvement layer further includes a second improvement layer, which is disposed between the quantum well active layer and the electron blocking layer; The second improvement layer is a second superlattice structure formed by alternating third and fourth sublayers, wherein the third sublayers are made of Al. a Ga 1-a N is used as the growth material, and the fourth sublayer uses Al. b Ga 1-b N is used as the growth material, the third sublayer is in contact with the quantum well active layer, and the fourth sublayer is in contact with the electron blocking layer; The proportion of Al component in the quantum barrier of the active layer of the quantum well is x, and the relationship between a, b and x satisfies 40%≤b≤x≤a≤100% and 5%≤ab≤30%.

5. The deep ultraviolet light-emitting diode according to claim 4, characterized in that, In the second superlattice structure, the thickness of the third sublayer ranges from 0.1 nm to 20 nm, and the thickness of the fourth sublayer ranges from 0.1 nm to 20 nm; the superlattice period of the second superlattice structure ranges from 1 to 50.

6. An epitaxial growth method for a deep ultraviolet light-emitting diode according to any one of claims 1 to 5, characterized in that, The method includes: An intrinsic layer is epitaxially grown on a substrate; An electron injection layer is epitaxially grown on the intrinsic layer; A quantum well active layer is epitaxially grown on the electron injection layer; An electron blocking layer is epitaxially grown on the active layer of the quantum well; A hole injection layer is epitaxially grown on the electron blocking layer; A P-type contact layer is epitaxially grown on the hole injection layer; The deep ultraviolet light-emitting diode further includes a leakage current improvement layer, which is an unintentionally doped layer.

7. The epitaxial growth method for a deep ultraviolet light-emitting diode according to claim 6, characterized in that, The step of epitaxially growing an electron-injected layer on the intrinsic layer further includes: A first improvement layer is epitaxially grown on the electron injection layer. The first improvement layer is a first superlattice structure formed by alternating first sublayers and second sublayers. The first sublayer uses aluminum nitride as the growth material, and the second sublayer uses gallium nitride as the growth material. The difference between the growth temperature of the first sublayer and the growth temperature of the second sublayer is between 20°C and 100°C; the intermediate temperature change time between the first sublayer and the second sublayer is between 20s and 200s.

8. The epitaxial growth method for a deep ultraviolet light-emitting diode according to claim 7, characterized in that, When the intermediate temperature change time between the first sublayer and the second sublayer is between 50s and 200s, after the second sublayer is epitaxially grown on the electron injection layer, a capping layer is epitaxially grown on the second sublayer at a first temperature, and the first sublayer is epitaxially grown on the capping layer at a second temperature. The thickness of the capping layer ranges from 0.1 nm to 1 nm, the second temperature is greater than the first temperature, and the material of the capping layer is the same as the material of the first sub-layer.

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