Deep ultraviolet light emitting diode and epitaxial growth method thereof

Abstract

The application provides 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 and a hole injection layer. The quantum well active layer comprises at least one potential well layer and at least two potential barrier layers arranged alternately, and each potential well layer is inserted between two adjacent potential barrier layers. The material of the potential well layer is aluminum gallium nitride. In the direction from the substrate to the quantum well active layer, the aluminum component content in the potential well layer gradually decreases and then gradually increases. The application limits the carriers in the potential well layer, reduces the absolute difference between the aluminum component content near the potential barrier layer in the potential well layer and the aluminum component content of the potential barrier layer, reduces the piezoelectric polarization intensity in the quantum well, further improves the wave function overlap rate of the electrons and holes in the quantum well active layer, and further improves the light emitting efficiency 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] In deep ultraviolet (DUV) light-emitting diodes (LEDs), AlGaN is a direct wide-bandgap semiconductor material. Its bandgap width can be continuously adjusted by changing the amount of Al doping (from GaN with a bandgap of 3.4 eV to AlN with a bandgap of 6.2 eV), achieving light emission in the spectral range of 365 nm to 200 nm. It also possesses excellent properties such as stable physicochemical properties, high temperature resistance, and radiation resistance, making it the best candidate material for fabricating semiconductor DUV light source devices. Furthermore, AlGaN-based DUVs offer numerous advantages over traditional mercury lamps, including smaller size, lower power consumption, environmental friendliness, safety, and higher integration, and are expected to achieve breakthroughs and widespread applications in the coming years, attracting increasing attention and importance in recent years.

[0003] However, the luminous efficiency of deep ultraviolet (LEX) LEDs based on AlGaN materials remains relatively low. This is because AlGaN has a wurtzite structure, which exhibits spontaneous polarization and piezoelectric polarization along the c-direction perpendicular lattice. This polarization generates a large polarization electric field within the material. The electric field generated by polarization causes the wave functions of electrons and holes to separate, reducing the wave function overlap ratio and thus lowering the luminous efficiency of the LEX LED. Specifically, the piezoelectric polarization of AlGaN is related to the internal stress of the thin film. When the material is subjected to stress, the c / a ratio (the ratio of the perpendicular lattice constant to the basal lattice constant) changes, thereby affecting the polarization intensity within the material.

[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 low luminous efficiency of the quantum well active layer in existing deep ultraviolet light-emitting diodes.

[0006] To solve the above-mentioned technical problems, the present invention first provides a deep ultraviolet light-emitting diode, which includes a substrate, an intrinsic layer, an electron injection layer, a quantum well active layer, an electron blocking layer and a hole injection layer stacked from bottom to top. The quantum well active layer includes at least one potential well layer and at least two potential barrier layers arranged alternately, with each potential well layer inserted between two adjacent potential barrier layers. The material of the potential well layer is aluminum gallium nitride.

[0007] In the direction from the substrate to the quantum well active layer, the aluminum content in the potential well layer first gradually decreases and then gradually increases.

[0008] In the deep ultraviolet light-emitting diode provided in the embodiments of the present invention, the thickness of the potential well layer ranges from 0.5 nm to 10 nm, and the mass percentage of aluminum component in the potential well layer ranges from 20% to 70%.

[0009] In the deep ultraviolet light-emitting diode provided in the embodiments of the present invention, the growth temperature of the potential well layer is first gradually decreased and then gradually increased.

[0010] In the deep ultraviolet light-emitting diode provided in the embodiments of the present invention, the aluminum component content in the barrier layer remains unchanged from the side surface of the barrier layer closer to the substrate to the side surface of the barrier layer farther from the substrate.

[0011] In the deep ultraviolet light-emitting diode provided in the embodiments of the present invention, the thickness of the barrier layer ranges from 0.5 nm to 10 nm, and the mass percentage of aluminum component in the barrier layer ranges from 30% to 75%.

[0012] In the deep ultraviolet light-emitting diode provided in the embodiments of the present invention, the growth temperature range of the quantum well active layer is 950 to 1100, and the five-to-three ratio parameter range of the quantum well active layer is 50 to 10000.

[0013] In this case, the barrier layer in the active layer of the quantum well uses SiH4 as an N-type dopant.

[0014] Accordingly, the present invention also provides an epitaxial growth method for deep ultraviolet light-emitting diodes, the method comprising:

[0015] An intrinsic layer is epitaxially grown on a substrate;

[0016] An electron-injected layer is epitaxially grown on the intrinsic layer;

[0017] A quantum well active layer is epitaxially grown on the electron injection layer;

[0018] An electron blocking layer is epitaxially grown on the active layer of a quantum well;

[0019] Epitaxial growth of a hole injection layer on an electron blocking layer;

[0020] The quantum well active layer includes at least one potential well layer and at least two potential barrier layers arranged alternately, with each potential well layer inserted between two adjacent potential barrier layers. The material of the potential well layer is aluminum gallium nitride. In the direction from the substrate to the quantum well active layer, the aluminum content in the potential well layer first gradually decreases and then gradually increases.

[0021] In the epitaxial growth method of deep ultraviolet light-emitting diode provided in the embodiments of the present invention, in the step of epitaxially growing a quantum well active layer on the electron injection layer, the growth temperature range of the quantum well active layer is 950 to 1100, and the quantum well active layer has a 5:3 ratio parameter, the range of which is 50 to 10000.

[0022] In this case, the barrier layer in the active layer of the quantum well uses SiH4 as an N-type dopant.

[0023] In the epitaxial growth method of deep ultraviolet light-emitting diode provided in the embodiments of the present invention, in the step of epitaxially growing each potential well layer, the flow rate of gallium source into the reaction cavity is gradually increased first, and then the flow rate of gallium source into the reaction cavity is gradually decreased.

[0024] In the epitaxial growth method of deep ultraviolet light-emitting diodes provided in the embodiments of the present invention, in the step of epitaxially growing each potential well layer, the growth temperature in the reaction chamber is gradually reduced first, and then the growth temperature in the reaction chamber is gradually increased.

[0025] The beneficial effects of this invention are as follows: Unlike existing technologies, this invention provides a deep ultraviolet (DUV) light-emitting diode and its epitaxial growth method. The DUV comprises, from bottom to top, a substrate, an intrinsic layer, an electron injection layer, a quantum well active layer, an electron blocking layer, and a hole injection layer. The quantum well active layer includes at least one potential well layer and at least two potential barrier layers alternately arranged, with each potential well layer inserted between two adjacent potential barrier layers. The material of the potential well layer is aluminum gallium nitride (AlGaN). In the direction from the substrate to the quantum well active layer, the aluminum content in the potential well layer first gradually decreases and then gradually increases. This invention, through substrate... In the direction towards the active layer of the quantum well, the aluminum content in the potential well layer is gradually reduced and then gradually increased. While confining the charge carriers inside the potential well layer, the absolute difference between the aluminum content on the side of the potential well layer near the barrier layer and the aluminum content in the barrier layer is reduced. This reduces the difference in lattice constant between the potential well layer and the barrier layer, thereby avoiding the compressive stress caused by the interface abrupt change between the potential well layer and the barrier layer. This further reduces the piezoelectric polarization intensity inside the quantum well, further improves the wave function overlap rate of electrons and holes in the active layer of the quantum well, and further improves the luminous efficiency of the deep ultraviolet light-emitting diode. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the cross-sectional structure of the deep ultraviolet light-emitting diode provided in an embodiment of the present invention;

[0027] Figure 2 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;

[0028] Figure 3AA graph showing the relative variation of aluminum content in the barrier layer and aluminum content in the well layer in a quantum well structure of a deep ultraviolet light-emitting diode (LELED) for existing technology.

[0029] Figure 3B The graph showing the relative change between the aluminum content of the barrier layer and the aluminum content of the well layer in the quantum well structure of the deep ultraviolet light-emitting diode provided by the present invention.

[0030] Figure 4A A schematic diagram of the electron wave function and hole wave function curves in a quantum well structure of a deep ultraviolet light-emitting diode provided for existing technology;

[0031] Figure 4B A schematic diagram of the electron wave function and hole wave function curves in the quantum well structure of the deep ultraviolet light-emitting diode provided by the present invention;

[0032] Figure 5 The graphs show the changes in light output power as a function of current for two deep ultraviolet light-emitting diodes with different structures. Detailed Implementation

[0033] 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.

[0034] Please see Figures 1 to 5 The present invention provides a deep ultraviolet light-emitting diode 100 and its epitaxial growth method, comprising a substrate 11, an intrinsic layer 12, an electron injection layer 13, a quantum well active layer 14, an electron blocking layer 15 and a hole injection layer 16 stacked from bottom to top.

[0035] Specifically, the quantum well active layer 14 includes at least one potential well layer 142 and at least two potential barrier layers 141 arranged alternately, with each potential well layer 142 inserted between two adjacent potential barrier layers 141, and the material of the potential well layer 142 is aluminum gallium nitride.

[0036] In the direction (D1) from the substrate 11 to the quantum well active layer 14, the aluminum content in the potential well layer 142 first gradually decreases and then gradually increases.

[0037] This invention, by gradually decreasing and then gradually increasing the aluminum content in the potential well layer 142 along the direction (D1) from the substrate 11 to the quantum well active layer 14, confines the charge carriers within the potential well layer 142 while reducing the absolute difference between the aluminum content in the potential well layer 142 and the barrier layer 141. This reduces the lattice constant difference between the potential well layer 142 and the barrier layer 141, thereby avoiding the compressive stress caused by the interface abrupt change between the potential well layer 142 and the barrier layer 141. Consequently, it reduces the piezoelectric polarization intensity within the quantum well active layer 14, further improves the wave function overlap rate of the quantum well active layer 14, and further enhances the luminous efficiency of the deep ultraviolet light-emitting diode 100.

[0038] The technical solution of this application will now be described in conjunction with specific embodiments.

[0039] Please see Figure 1 , Figure 1 This is a schematic cross-sectional view 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, an electron injection layer 13, a quantum well active layer 14, an electron blocking layer 15, and a hole injection layer 16 stacked from bottom to top;

[0040] The quantum well active layer 14 includes at least one potential well layer 142 and at least two potential barrier layers 141 arranged alternately, with each potential well layer 142 inserted between two adjacent potential barrier layers 141, and the material of the potential well layer 142 is aluminum gallium nitride.

[0041] Furthermore, in the direction (D1) from the substrate 11 to the quantum well active layer 14, the aluminum content in the potential well layer 142 first gradually decreases and then gradually increases.

[0042] In this embodiment of the invention, the substrate 11 is made of sapphire. Sapphire has many advantages: firstly, its production technology is mature and the device quality is good; secondly, sapphire has excellent stability and can be used in high-temperature growth processes; and finally, sapphire has high mechanical strength and is easy to handle and clean. Therefore, most processes generally use sapphire as the substrate 11.

[0043] 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 to 800, and the thickness ranges from 10 nm to 50 nm; the aluminum nitride intrinsic layer is aluminum nitride, the growth temperature ranges from 1200 to 1400, and the thickness ranges from 500 nm to 4000 nm.

[0044] In this embodiment of the invention, the electron injection layer 13 is made of N-type doped aluminum gallium nitride material, and the dopant is SiH4; wherein, the aluminum content in the electron injection layer 13 is between 20% and 90%, the thickness of the electron injection layer 13 is between 500 nm and 4000 nm, and the growth temperature of the electron injection layer 13 is between 900 and 1200 °C.

[0045] In this embodiment of the invention, the quantum well active layer 14 is disposed on the electron injection layer 13, and the growth temperature of the quantum well active layer 14 is between 900 and 1100 degrees Celsius.

[0046] Specifically, the quantum well active layer 14 is a periodically arranged AlGaN multilayer periodic structure. Each periodic structure includes a barrier layer 141 and a well layer 142. Each well layer 142 is inserted between two adjacent barrier layers 141. The material of both the barrier layer 141 and the well layer 142 is aluminum gallium nitride. The only difference between the barrier layer 141 and the well layer 142 is the content of aluminum composition.

[0047] Furthermore, the total aluminum content of each potential well layer 142 is lower than the total aluminum content of each potential barrier layer 141, in order to ensure that the charge carriers in the quantum well active layer 14 are confined within the potential well layer 142.

[0048] Furthermore, along the direction (D1) from the substrate 11 to the quantum well active layer 14, the aluminum content in the potential well layer 142 gradually decreases and then gradually increases. This arrangement ensures that the absolute difference between the aluminum content in the potential well layer 142 near the barrier layer 141 and the aluminum content in the barrier layer 141 is reduced, thereby reducing the lattice constant difference between the potential well layer 142 and the barrier layer 141 (the piezoelectric stress inside the quantum well active layer 14 originates from the lattice constant difference between the potential well layer 142 and the barrier layer 141; the larger the lattice constant difference, the greater the piezoelectric stress). This avoids the compressive stress caused by the interface abrupt change between the potential well layer 142 and the barrier layer 141, thereby reducing the piezoelectric polarization intensity inside the quantum well active layer 14, further improving the wave function overlap rate of the quantum well active layer 14, and further enhancing the luminous efficiency of the deep ultraviolet light-emitting diode 100.

[0049] Specifically, the lattice constants of AlN and GaN are fixed and independent of AlGaN. The lattice constant of AlGaN is determined by the Al content. Assuming the Al content in AlGaN material is x, the lattice constant of AlGaN material can be approximately calculated using the following formula:

[0050]

[0051] Among them, a AlNLet a be the lattice constant of AlN. GaN Let be the lattice constant of GaN. is the lattice constant of AlGaN material.

[0052] Therefore, the higher the Al content in AlGaN materials, the greater the lattice constant.

[0053] In this embodiment of the invention, the thickness of the potential well layer 142 ranges from 0.5 nm to 10 nm, and the mass percentage of aluminum in the potential well layer 142 ranges from 20% to 70%. Specifically, when the mass percentage of aluminum in the potential well layer 142 is less than 20%, the quantum well active layer 14 has difficulty emitting light with wavelengths below 280 nm; when the mass percentage of aluminum in the potential well layer 142 is greater than 70%, carrier injection becomes difficult, leading to electrical anomalies.

[0054] In this embodiment of the invention, the growth temperature of the potential well layer 142 is first gradually decreased and then gradually increased; this is because the growth temperature also affects the Al component content in the epitaxially grown AlGaN material, wherein the higher the growth temperature, the higher the Al component content in the epitaxially grown AlGaN material.

[0055] In this embodiment of the invention, the aluminum content in the barrier layer 141 remains constant from the side of the barrier layer 141 closest to the substrate to the side of the barrier layer 141 furthest from the substrate. Since Al atoms are relatively small, when they replace Ga atoms, they decrease the lattice constant of the epitaxial layer, thereby widening the bandgap. Therefore, keeping the aluminum content in the barrier layer 141 constant can effectively stabilize the brightness characteristics of the deep ultraviolet light-emitting diode 100.

[0056] Furthermore, the thickness of the barrier layer 141 ranges from 0.5 nm to 10 nm, and the mass percentage of aluminum component in the barrier layer 141 ranges from 30% to 75%.

[0057] In this embodiment of the invention, the growth temperature range of the quantum well active layer 14 is 950 to 1100, and the range of the 5:3 ratio parameter of the quantum well active layer is 50 to 10000.

[0058] Among them, the 5:3 ratio parameter refers to the molar ratio of group V source to group III source introduced into the reaction chamber during epitaxial growth. Under the condition of high 5:3 ratio parameter, the grown epitaxial layer will bring higher epitaxial lattice quality; conversely, under the condition of low 5:3 ratio parameter, although the epitaxial lattice quality of the grown epitaxial layer is poor, a flat epitaxial lattice surface can be obtained.

[0059] In this embodiment of the invention, the barrier layer 141 in the active layer 14 of the quantum well uses SiH4 as an N-type dopant; wherein, appropriate N-type doping in the barrier layer 141 can reduce the loss of interface charge in the active layer 14 of the quantum well and increase the electron carrier concentration.

[0060] In this embodiment of the invention, an electron blocking layer 15 is disposed on the active layer 14 of the quantum well, and the growth temperature of the electron blocking layer 15 is between 700 and 1100°C; wherein, the electron blocking layer 15 is a single-layer AlGaN structure, the electron blocking layer 15 is a P-type doped semiconductor material, and magnesia pyrocene is used as the P-type dopant.

[0061] Furthermore, the percentage of aluminum in the electron blocking layer 15 ranges from 50% to 100%, and the thickness of the electron blocking layer 15 ranges from 1 nm to 100 nm.

[0062] In this embodiment of the invention, the hole injection layer 16 is disposed on the electron blocking layer 15, and the growth temperature of the hole injection layer 16 is between 700 and 1100 °C. The material of the hole injection layer 16 is p-type doped aluminum gallium nitride, the percentage of aluminum content in the hole injection layer 16 is between 20% and 60%, the thickness of the hole injection layer 16 is between 1 nm and 100 nm, and magnesia pyrocene is used as the dopant in the hole injection layer 16.

[0063] Furthermore, in this embodiment of the invention, the deep ultraviolet light-emitting diode 100 further includes an N-type electrode 17 and a P-type electrode 18;

[0064] In this structure, a stepped structure is formed between the quantum well active layer 14 and the electron injection layer 13, and the area of ​​the quantum well active layer 14 is smaller than the area of ​​the electron injection layer 13. The P-type electrode 18 is disposed on the hole injection layer 16, and the N-type electrode 17 is disposed at the stepped structure of the electron injection layer 13.

[0065] 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 1 as well as Figure 2 , Figure 2 This is a process flow diagram of the epitaxial growth method for a deep ultraviolet light-emitting diode 100 provided in an embodiment of the present invention. Specifically, the epitaxial growth method includes:

[0066] S10, an intrinsic layer 12 is epitaxially grown on a substrate 11.

[0067] Specifically, S10 also includes:

[0068] First, a substrate 11 is provided, which is made of sapphire material. Then, a low-temperature buffer layer is grown on the substrate 11 at a temperature of 400–800°C, with a thickness ranging from 10 nm to 50 nm. Finally, the growth temperature is increased to between 1200 and 1400°C, and an intrinsic aluminum nitride layer is grown on the low-temperature buffer layer, with a thickness ranging from 500 nm to 4000 nm. The low-temperature buffer layer and the intrinsic aluminum nitride layer constitute the intrinsic layer 12, and both the low-temperature buffer layer and the intrinsic aluminum nitride layer are made of aluminum nitride.

[0069] S20, an electron injection layer 13 is epitaxially grown on intrinsic layer 12.

[0070] Specifically, S20 also includes:

[0071] First, the growth temperature is lowered to between 900 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; the aluminum content ranges from 20% to 90%, and the N-type dopant is SiH4.

[0072] S30, a quantum well active layer 14 is epitaxially grown on the electron injection layer 13.

[0073] Specifically, S30 also includes:

[0074] First, the growth temperature in the reaction chamber is reduced to between 900 and 1200 degrees Celsius, and a quantum well active layer 14 is epitaxially grown on the electron injection layer 13. The quantum well active layer 14 is a periodically arranged AlGaN multilayer periodic structure. Each periodic structure includes a barrier layer 141 and a well layer 142. The material of both the barrier layer 141 and the well layer 142 is aluminum gallium nitride. The only difference between the barrier layer 141 and the well layer 142 is the content of aluminum composition.

[0075] In the direction (D1) from the substrate 11 to the quantum well active layer 14, the aluminum content in the potential well layer 142 first gradually decreases and then gradually increases.

[0076] Specifically, the growth temperature range of the quantum well active layer 14 is 950 to 1100, and the quantum well active layer 14 has a 5:3 ratio parameter, which ranges from 50 to 10000.

[0077] Among them, the barrier layer 141 in the active layer 14 of the quantum well uses SiH4 as an N-type dopant.

[0078] Furthermore, in the step of epitaxially growing each potential well layer 142, the flow rate of the gallium source into the reaction chamber is gradually increased first, and then the flow rate of the gallium source into the reaction chamber is gradually decreased. The gallium source is trimethylgallium.

[0079] Furthermore, during the epitaxial growth of each potential well layer 142, the growth temperature inside the reaction chamber is gradually reduced first, and then gradually increased.

[0080] In this embodiment of the invention, the thickness of the potential well layer 142 ranges from 0.5 nm to 10 nm, and the mass percentage of aluminum component in the potential well layer 142 ranges from 20% to 70%.

[0081] In this embodiment of the invention, the aluminum content in the barrier layer 141 remains unchanged from the side surface of the barrier layer 141 closest to the substrate to the side surface of the barrier layer 141 furthest from the substrate; the thickness of the barrier layer 141 ranges from 0.5 nm to 10 nm, and the mass percentage of the aluminum component in the barrier layer 141 ranges from 30% to 75%.

[0082] In this embodiment of the invention, the barrier layer 141 in the active layer 14 of the quantum well uses SiH4 as an N-type dopant.

[0083] S40, an electron blocking layer 15 is epitaxially grown on the active layer 14 of the quantum well.

[0084] Specifically, S40 also includes:

[0085] First, the temperature of the reaction chamber is maintained between 700 and 1100 °C, and an electron blocking layer 15 is epitaxially grown on the active layer 14 of the quantum well. The electron blocking layer 15 is a single-layer AlGaN structure and is a P-type doped semiconductor material, using magnesium pyrocene as the P-type dopant.

[0086] Specifically, the percentage of aluminum content in the electron blocking layer 15 ranges from 45% to 100%, and the thickness of the electron blocking layer 15 ranges from 1 nm to 100 nm.

[0087] S50, a hole injection layer 16 is epitaxially grown on the electron blocking layer 15.

[0088] Specifically, the S50 also includes:

[0089] The growth temperature is maintained between 700 and 1100 °C, and a hole injection layer 16 is epitaxially grown on the electron blocking layer 15. The hole injection layer 16 is made of p-type doped aluminum gallium nitride, with the percentage of aluminum content in the hole injection layer 16 ranging from 0 to 100%, and the thickness of the hole injection layer 16 ranging from 1 nm to 100 nm. Magnesium thiocarbamate is used as the p-type dopant in the hole injection layer 16.

[0090] Next, an N-type electrode 17 is disposed at the stepped structure of the electron injection layer 13, with the N-type electrode 17 being opposite to and spaced apart from the quantum well active layer 14; finally, a P-type electrode 18 is formed on the hole injection layer 16.

[0091] In this embodiment of the invention, after the deep ultraviolet light-emitting diode 100 is fabricated, it is compared with the deep ultraviolet light-emitting diode 100 of the prior art. The light output power (mW) of the two deep ultraviolet light-emitting diodes 100 is tested under different driving currents (mA).

[0092] Embodiments of the present invention:

[0093] The film structure of the deep ultraviolet light-emitting diode 100 provided by the present invention has approximately the same structure and materials from bottom to top, from the substrate 11 to the hole injection layer 16, as shown below:

[0094] Substrate 11 is made of sapphire.

[0095] Intrinsic layer 12 is made of aluminum nitride and has a thickness of 2000 nm.

[0096] The electron injection layer 13 is made of Si-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 the thickness is 2500 nm.

[0097] In the quantum well active layer 14, the barrier layer 141 has a thickness of 10 nm and an Al content of 0.55; in the direction (D1) from the substrate 11 to the quantum well active layer 14, the Al content of the well layer 142 first gradually changes from 0.55 to 0.4, and then gradually changes from 0.4 to 0.55, and the thickness of the well layer 142 is 1.8 nm.

[0098] Electron blocking layer 15 is a single-layer AlGaN structure with a thickness of 50 nm and an Al composition of 60% by mass.

[0099] The hole injection layer 16 is made of p-type doped aluminum gallium nitride. The mass percentage of aluminum in the hole injection layer 16 is 40%, the thickness is 50 nm, and magnesia pyrocene is used as the p-type dopant.

[0100] Furthermore, using conventional methods, N-type electrodes 17 of the same material are disposed on the electron injection layer 13, and P-type electrodes 18 of the same material are disposed on the hole injection layer 16, to form a complete epitaxial chip structure. The specific process is not described in detail here. Among them, both the N-type electrode 17 and the P-type electrode 18 are multilayer composite metal materials.

[0101] Comparative Example:

[0102] The deep ultraviolet light-emitting diode 100 fabricated by conventional processes has a quantum well active layer 14 in which the barrier layer 141 has a thickness of 10 nm and an Al content of 0.55; the potential well layer 142 has a thickness of 2 nm and an Al content of 0.55; the other film layer structures of the comparative embodiment are the same as the other film layer structures of the embodiments of the present invention.

[0103] Please see Figure 3A as well as Figure 3B , Figure 3A A graph showing the relative variation of aluminum content in the barrier layer and aluminum content in the well layer in a quantum well structure of a deep ultraviolet light-emitting diode (LELED) for existing technology. Figure 3B The graph showing the relative change between the aluminum content of the barrier layer and the aluminum content of the well layer in the quantum well structure of the deep ultraviolet light-emitting diode provided by the present invention.

[0104] The quantum well active layer 14 structure (traditional quantum well structure) in the comparative embodiment is as follows: the barrier layer 141 has a thickness of 10 nm and the Al content in the barrier layer 141 is 0.55; the well layer 142 has a thickness of 2 nm and the Al content in the well layer 142 is 0.55.

[0105] The quantum well active layer 14 structure (V-shaped quantum well structure) in this embodiment of the invention is as follows: the thickness of the barrier layer 141 is 10 nm and the Al content in the barrier layer 141 is 0.55; in the direction (D1) from the substrate 11 to the quantum well active layer 14, the Al content of the well layer 142 first gradually changes from 0.55 to 0.4, and then gradually changes from 0.4 to 0.55, and the thickness of the well layer 142 is 1.8 nm.

[0106] Please see Figure 4A as well as Figure 4B , Figure 4A A schematic diagram of the electron wave function and hole wave function curves in a quantum well structure of a deep ultraviolet light-emitting diode provided for existing technology; Figure 4B A schematic diagram of the electron wave function and hole wave function of the quantum well structure in the deep ultraviolet light-emitting diode provided by the present invention (the horizontal axis represents the equilibrium position of each particle in the medium, and the vertical axis represents the displacement of the particle from the equilibrium position).

[0107] Specifically, the wavefunction overlap rates of electrons and holes in the quantum well region of two deep ultraviolet light-emitting diodes can be obtained through theoretical calculations. For example... Figure 4A as well as Figure 4B As shown, Figure 4A The shaded area represents the wavefunction overlap rate of the quantum well structure in the comparative embodiment. Figure 4BThe shaded area represents the wavefunction overlap rate of the V-shaped quantum well structure proposed in this invention. Generally, the greater the wavefunction overlap rate between electrons and holes, the higher the quantum efficiency of the deep ultraviolet light-emitting diode 100. The calculation results show that the V-shaped quantum well active region structure proposed in this invention can significantly improve the quantum efficiency of the deep ultraviolet light-emitting diode 100.

[0108] Please see Figure 5 , Figure 5 The graphs show the optical output power of two deep ultraviolet light-emitting diodes 100 with different structures as a function of current. Specifically, under different driving currents (mA), the optical output power (mW) of each deep ultraviolet light-emitting diode 100 as a function of driving current was measured. Figure 5 As shown.

[0109] Specifically, by Figure 5 It can be seen that chip tests were performed on a conventional deep ultraviolet light-emitting diode 100 (comparative embodiment) and a deep ultraviolet light-emitting diode 100 with a V-shaped quantum well structure (embodiment of the present invention). Among them, when the injection current is 40mA, the light output power of the conventional deep ultraviolet light-emitting diode 100 is 9.28mW; while the light output power of the deep ultraviolet light-emitting diode 100 with a V-shaped quantum well structure is 10.07mW. This is because the V-shaped quantum well structure increases the wave function overlap rate of electrons and holes in the quantum well, thereby improving the light output power of the deep ultraviolet light-emitting diode 100.

[0110] In summary, unlike existing technologies, the deep ultraviolet light-emitting diode 100 with a V-shaped quantum well structure proposed in this invention avoids the compressive stress caused by the interface abrupt change in the potential well layer 142 and the barrier layer 141, reduces the piezoelectric polarization intensity inside the active quantum well layer 14, and increases the wave function overlap rate of electrons and holes in the active quantum well layer 14, thereby improving the light output power of the deep ultraviolet light-emitting diode 100.

[0111] 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.

[0112] 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, The device includes a substrate, an intrinsic layer, an electron injection layer, a quantum well active layer, an electron blocking layer, and a hole injection layer stacked from bottom to top. The quantum well active layer includes at least one potential well layer and at least two potential barrier layers arranged alternately. Each potential well layer is inserted between two adjacent potential barrier layers. The material of the potential well layer is aluminum gallium nitride. In the direction from the substrate to the quantum well active layer, the aluminum content in the potential well layer first gradually decreases and then gradually increases; the thickness of the potential well layer ranges from 0.5 nm to 10 nm, and the mass percentage of aluminum in the potential well layer ranges from 20% to 70%. The aluminum content in the barrier layer remains constant from the side of the barrier layer closest to the substrate to the side of the barrier layer furthest from the substrate; the thickness of the barrier layer ranges from 0.5 nm to 10 nm, and the mass percentage of the aluminum content in the barrier layer ranges from 30% to 75%.

2. The deep ultraviolet light-emitting diode according to claim 1, characterized in that, The growth temperature of the potential well layer first gradually decreases and then gradually increases.

3. The deep ultraviolet light-emitting diode according to any one of claims 1 to 2, characterized in that, The growth temperature range of the quantum well active layer is 950℃~1100℃, and the range of the 5-to-3 ratio parameter of the quantum well active layer is 50~10000. The barrier layer in the active layer of the quantum well uses SiH4 as an N-type dopant.

4. An epitaxial growth method for a deep ultraviolet light-emitting diode according to any one of claims 1 to 3, 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; The quantum well active layer includes at least one potential well layer and at least two potential barrier layers arranged alternately, with each potential well layer inserted between two adjacent potential barrier layers. The material of the potential well layer is aluminum gallium nitride. In the direction from the substrate to the quantum well active layer, the aluminum content in the potential well layer first gradually decreases and then gradually increases.

5. The epitaxial growth method for deep ultraviolet light-emitting diodes according to claim 4, characterized in that, In the step of epitaxially growing a quantum well active layer on the electron injection layer, the growth temperature of the quantum well active layer is in the range of 950℃~1100℃, and the quantum well active layer has a 5:3 ratio parameter, which is in the range of 50~10000. The barrier layer in the active layer of the quantum well uses SiH4 as an N-type dopant.

6. The epitaxial growth method for a deep ultraviolet light-emitting diode according to claim 5, characterized in that, In the step of epitaxially growing each of the potential well layers, the flow rate of the gallium source into the reaction chamber is first gradually increased, and then the flow rate of the gallium source into the reaction chamber is gradually decreased.

7. The epitaxial growth method for a deep ultraviolet light-emitting diode according to claim 6, characterized in that, In the step of epitaxially growing each of the potential well layers, the growth temperature in the reaction chamber is first gradually decreased, and then the growth temperature in the reaction chamber is gradually increased.

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