CN110600595A - Aluminum gallium nitrogen-based ultraviolet LED epitaxial structure and ultraviolet LED lamp - Google Patents

Abstract

The invention relates to an AlGaN-based ultraviolet LED epitaxial structure and an ultraviolet LED lamp. The AlGaN-based ultraviolet LED epitaxial structure comprises a substrate, a buffer layer, a first AlGaN layer, a light-emitting layer and a second aluminum Gallium nitride layer; the second AlGaN layer includes a plurality of second AlGaN sublayers, the plurality of second AlGaN sublayers are stacked in sequence, and the aluminum composition of the plurality of second AlGaN sublayers is different from that of The aluminum composition of the second AlGaN sublayer connected to the light emitting layer is larger than the aluminum composition of other second AlGaN sublayers. The aluminum composition of the second AlGaN sublayer near the light-emitting layer is the largest, and the aluminum composition of the second AlGaN sublayer far away from the light-emitting layer is the smallest. The second AlGaN sublayers with different compositions weaken the second AlGaN sublayer. The built-in electric field of the nitrogen layer weakens the piezoelectric polarization effect between the second AlGaN layer and the light-emitting layer, thereby increasing the effective injection rate of holes, increasing the radiative recombination rate of electrons and holes, and improving the aluminum Intrinsic Quantum Rate and Luminous Efficiency of Gallium Nitride-Based UV LED Epitaxial Structure.

Description

AlGaN-based ultraviolet LED epitaxial structure and ultraviolet LED lamp

technical field

The invention relates to the technical field of semiconductors, in particular to an aluminum gallium nitrogen-based ultraviolet LED epitaxial structure and an ultraviolet LED lamp.

Background technique

With the continuous development of light emitting diode (Light Emitting Diode, LED) technology, ultraviolet light emitting diodes are becoming more and more important in the commercial field, and have great application value. Moreover, compared with the traditional ultraviolet light source mercury lamp, ultraviolet LED has the advantages of super long life, no heat radiation, high energy, uniform irradiation, high efficiency, small size and no toxic substances, which makes ultraviolet LED the most likely Replace the traditional UV light source. Therefore, UV LEDs are receiving more and more attention from researchers. Among them, the luminous power of the ultraviolet LED is related to the internal quantum rate of the light emitted by the ultraviolet LED epitaxial wafer inside. Currently, the preparation of the ultraviolet LED epitaxial wafer mainly uses the III-nitride AlGaN (aluminum gallium nitrogen) material.

However, due to the strong spontaneous and piezoelectric polarization between III-nitride materials, a strong polarization electric field is generated, which eventually leads to the leakage of electrons in the light-emitting layer, which reduces the radiative recombination efficiency of electrons and holes in the light-emitting layer. As a result, the internal quantum rate of the light emitted by the ultraviolet LED epitaxial wafer is low, which in turn causes the luminous power of the ultraviolet LED epitaxial wafer to be low.

Contents of the invention

Based on this, it is necessary to provide an AlGaN-based ultraviolet LED epitaxial structure and an ultraviolet LED lamp with a simple structure and improved internal quantum rate and luminous efficiency.

An AlGaN-based ultraviolet LED epitaxial structure, comprising: a substrate, a buffer layer, a first AlGaN layer, a light-emitting layer, and a second AlGaN layer that are sequentially stacked, and the first AlGaN layer is used for Provide electrons, the second AlGaN layer is used to provide holes, and the light-emitting layer is used for radiation recombination of electrons and holes to emit light; the second AlGaN layer includes a plurality of second AlGaN sublayers A plurality of second AlGaN sublayers are stacked in sequence, the aluminum components of the plurality of second AlGaN sublayers are different, and the aluminum gallium nitride sublayers connected to the light emitting layer are The aluminum composition is greater than that of the other second AlGaN sublayers.

In one of the embodiments, the aluminum composition of each of the second AlGaN sublayers decreases sequentially from being close to the light emitting layer to being far away from the light emitting layer.

In one embodiment, the aluminum composition of each of the second AlGaN sublayers decreases linearly from being close to the light emitting layer to being far away from the light emitting layer.

In one embodiment, the aluminum composition of the second AlGaN sub-layer is 0-0.8.

In one embodiment, the aluminum composition of the second AlGaN sub-layer is 0.05-0.65.

In one embodiment, the plurality of second AlGaN sublayers have the same thickness.

In one embodiment, the thickness of the second AlGaN sublayer is 20-30 nm.

In one embodiment, the dopant atoms of the second AlGaN layer include magnesium atoms.

In one embodiment, the doping concentration of magnesium atoms in the second AlGaN layer is 1×10 ¹⁷ cm ⁻³ .

An ultraviolet LED lamp, comprising a lamp holder, a lampshade, and the AlGaN-based ultraviolet LED epitaxial structure described in any of the above embodiments, the AlGaN-based ultraviolet LED epitaxial structure is arranged on the lamp holder, the The lampshade is connected with the lamp holder, and is covered with the AlGaN-based ultraviolet LED epitaxial structure.

In the above-mentioned AlGaN-based ultraviolet LED epitaxial structure and ultraviolet LED lamp, the aluminum component of the second AlGaN sublayer close to the light-emitting layer is the largest, which is used to reduce the leakage of electrons from the light-emitting layer; the second AlGaN sublayer far away from the light-emitting layer The aluminum composition of the AlGaN sublayer is the smallest, which is used to provide holes to the light-emitting layer; the second AlGaN sublayer with different composition weakens the built-in electric field of the second AlGaN layer, making the second AlGaN The piezoelectric polarization effect between the layer and the light-emitting layer is weakened, thereby increasing the effective injection rate of holes, so that the second AlGaN sublayer has the functions of blocking electron leakage and increasing the hole injection rate, thereby making electrons and holes The radiation recombination rate of the hole is improved, and the internal quantum rate and luminous rate of the AlGaN-based ultraviolet LED epitaxial structure are improved.

Description of drawings

FIG. 1 is a schematic structural view of an epitaxial structure of an AlGaN-based ultraviolet LED according to an embodiment.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the associated drawings. Preferred embodiments of the invention are shown in the accompanying drawings. However, the present invention can be embodied in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

It should be noted that when an element is referred to as being “disposed on” another element, it may be directly on the other element or there may also be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and similar expressions are used herein for purposes of illustration only and are not intended to represent the only embodiments.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terms used in the description of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The invention relates to an epitaxial structure of an aluminum gallium nitrogen-based ultraviolet LED. For example, the AlGaN-based ultraviolet LED epitaxial structure includes: a substrate, a buffer layer, a first AlGaN layer, a light-emitting layer, and a second AlGaN layer that are sequentially stacked, and the first AlGaN layer is used for The second AlGaN layer is used for providing electrons, the second AlGaN layer is used for providing holes, and the light-emitting layer is used for radiation recombination of electrons and holes to emit light; the second AlGaN layer includes a plurality of second AlGaN layers layer, a plurality of second AlGaN sublayers are stacked in sequence, the aluminum components of the plurality of second AlGaN sublayers are different, and the second AlGaN sublayer connected to the light emitting layer The aluminum composition of the second AlGaN sublayer is greater than that of the other second AlGaN sublayers. The aluminum composition of the second AlGaN sublayer close to the light-emitting layer is the largest, which is used to reduce the leakage of electrons from the light-emitting layer; the aluminum composition of the second AlGaN sublayer far away from the light-emitting layer is the smallest, used to emit light The layer provides holes; the second AlGaN sublayer with different components weakens the built-in electric field of the second AlGaN layer, so that the piezoelectric polarization effect between the second AlGaN layer and the light-emitting layer is weakened, Thereby improving the effective injection rate of holes, so that the second AlGaN sublayer has the functions of blocking electron leakage and increasing the hole injection rate, thereby improving the radiative recombination rate of electrons and holes, and improving the AlGaN-based ultraviolet radiation. Intrinsic Quantum Rate and Luminous Efficiency of LED Epitaxial Structures.

Please refer to FIG. 1 , which is a schematic structural diagram of an epitaxial structure of an AlGaN-based ultraviolet LED according to an embodiment of the present invention.

An AlGaN-based ultraviolet LED epitaxial structure 10, comprising: a substrate 100, a buffer layer 200, a first AlGaN layer 300, a light-emitting layer 400, and a second AlGaN layer 500, which are sequentially stacked. The AlGaN layer 300 is used to provide electrons, the second AlGaN layer 500 is used to provide holes, and the light-emitting layer 400 is used for radiation recombination of electrons and holes to emit light; the second AlGaN layer 500 It includes a plurality of second AlGaN sublayers 510, the plurality of second AlGaN sublayers 510 are stacked in sequence, and the aluminum components of the plurality of second AlGaN sublayers 510 are different from the light-emitting The aluminum composition of the second AlGaN sublayer to which layer 400 is connected is greater than the aluminum composition of the other second AlGaN sublayers.

In this embodiment, the aluminum composition of the second AlGaN sublayer is the aluminum content in the material of the second AlGaN sublayer. The aluminum composition of the second AlGaN sublayer 510 close to the light emitting layer 400 is the largest, which is used to reduce the leakage of electrons from the light emitting layer 400; the aluminum composition of the second AlGaN sublayer 510 far away from the light emitting layer 400 is the smallest , used to provide holes to the light-emitting layer 400; the second AlGaN sublayer 510 with different components weakens the built-in electric field of the second AlGaN layer 500, so that the second AlGaN layer 500 and the light-emitting layer 400 The piezoelectric polarization effect between them is weakened, thereby increasing the effective injection rate of holes, so that the second AlGaN sublayer 510 has the functions of blocking electron leakage and increasing the hole injection rate, thereby making the radiation of electrons and holes The recombination rate is improved, and the internal quantum rate and luminous rate of the AlGaN-based ultraviolet LED epitaxial structure are improved.

In one embodiment, please refer to FIG. 1 , the aluminum composition of each of the second AlGaN sub-layers 510 decreases sequentially from close to the light emitting layer 400 to away from the light emitting layer 400 . Since the diAlGaN layer is composed of a plurality of second AlGaN sublayers 510, and each of the second AlGaN sublayers 510 has a different aluminum composition, that is, it is close to the light emitting The second AlGaN sublayer 510 of the layer 400 has the largest aluminum composition, and the second AlGaN sublayer 510 furthest from the light emitting layer 400 has the smallest Al composition. In this embodiment, the second AlGaN sublayer 510 connected to the light emitting layer 400 is recorded as the first layer, and the second AlGaN sublayer 510 that is farthest from the light emitting layer 400 Layer 510 is denoted as a second layer, and the second AlGaN sublayer 510 located between said first layer and said second layer is denoted as a third layer, said third layer comprising at least one third sublayer, The aluminum composition of the first layer is the largest, the aluminum composition of the second layer is the smallest, and the aluminum composition of the third sublayer is between the aluminum composition of the first layer and the aluminum composition of the second layer. Among the components, that is, the aluminum component of the third sublayer is smaller than the aluminum component of the first layer and larger than the aluminum component of the second layer. Since the aluminum composition of the first layer is the largest, the electrons in the light emitting layer 400 are blocked by the first layer, reducing the leakage of electrons in the light emitting layer 400 to the second AlGaN layer In 500, it plays the function of blocking electron leakage; the aluminum component of the second layer is the smallest, and the second layer is used to connect with the external electrode to provide a high concentration of holes, and the third layer The aluminum composition of the first layer is smaller than that of the first layer, and is used to provide a high concentration of holes together with the second layer. In this way, the second AlGaN layer 500 is composed of the first layer, the second layer and the third layer, that is, the second AlGaN layer 500 is composed of a second aluminum alloy with different aluminum components. Gallium nitride sublayer 510, that is, the second AlGaN layer 500 is composed of the second AlGaN sublayer 510 whose aluminum composition decreases successively, so that the adjacent layers in the second AlGaN layer 500 An electric field opposite to the built-in electric field is formed between the two second AlGaN sub-layers 510, so that the built-in electric field of the second AlGaN layer 500 is weakened, so that the second AlGaN layer 500 and The piezoelectric polarization effect between the light-emitting layers 400 is weakened, which improves the effective injection rate of holes, so that the second AlGaN sublayer 510 has the functions of blocking electron leakage and increasing the hole injection rate, and improves the electron and hole injection rate. The radiative recombination rate of the hole, thereby improving the internal quantum rate and luminance of the AlGaN-based UV LED epitaxial structure.

In one embodiment, referring to FIG. 1 , the aluminum composition of each second AlGaN sub-layer 510 decreases linearly from close to the light emitting layer 400 to away from the light emitting layer 400 . In this embodiment, the number of the second AlGaN sub-layers 510 is four layers, from close to the light-emitting layer 400 to away from the light-emitting layer 400, the second AlGaN sub-layers 500 include sequentially stacked The first polarized layer, the second polarized layer, the third polarized layer and the fourth polarized layer, the first polarized layer and the side of the light emitting layer 400 away from the first AlGaN layer 300 connected, the second polarized layer is connected to the first polarized layer away from the light emitting layer 400, the third polarized layer is connected to the second polarized layer away from the first polarized layer, The fourth polarized layer is connected to the third polarized layer away from the second polarized layer. The aluminum composition of the first polarized layer, the aluminum composition of the second polarized layer, the aluminum composition of the third polarized layer, and the aluminum composition of the fourth polarized layer decrease linearly in sequence , that is, the aluminum composition of the first polarized layer, the aluminum composition of the second polarized layer, the aluminum composition of the third polarized layer, and the aluminum composition of the fourth polarized layer are The arithmetic sequence is arranged, that is, the absolute value of the difference between the aluminum components of two adjacent second AlGaN sub-layers 510 is equal. In this way, the aluminum composition of the plurality of second AlGaN sub-layers 510 decreases linearly, so that the electric field formed between two adjacent second AlGaN sub-layers 510 is more uniform, so that the first The weakening of the built-in electric field of the diAlGaN layer 500 is uniform, that is, the electric field intensity of the built-in electric field of the second AlGaN layer 500 is uniformly weakened sequentially, so that the built-in electric field of the second AlGaN layer 500 When the electric field is uniformly weakened, the effective injection rate of holes is increased, so that the second AlGaN sublayer 510 has the functions of blocking electron leakage and increasing the hole injection rate, and improving the radiative recombination rate of electrons and holes, thereby The internal quantum rate and luminous efficiency of the AlGaN-based ultraviolet LED epitaxial structure are improved.

In one embodiment, please refer to FIG. 1 , the aluminum composition of the second AlGaN sublayer 510 is 0˜0.8. In one of the embodiments, the aluminum composition of the second AlGaN sub-layer is 0-0.8 and not 0. In this embodiment, the second AlGaN layer 500 includes four second AlGaN sublayers 510, and the aluminum composition of the four second AlGaN sublayers 510 is between 0 and 0.8, wherein, The aluminum composition of the second AlGaN sublayer 510 close to the light emitting layer 400 is the largest, that is, the aluminum composition of the second AlGaN sublayer 510 close to the light emitting layer 400 is less than and close to 0.8; The aluminum composition of the second AlGaN sublayer 510 at the farthest position of the light emitting layer 400 is the smallest, that is, the aluminum composition of the second AlGaN sublayer 510 at the farthest position from the light emitting layer 400 is greater than and close to 0; the aluminum composition of the second AlGaN sublayer 510 located between the two second AlGaN sublayers 510 is between 0 and 0.8. In this way, the aluminum composition of the four second AlGaN sublayers 510 is different, and the aluminum composition of the second AlGaN sublayer 510 close to the light emitting layer 400 is the largest, as an electron blocking layer, Its function is to block electrons in the light emitting layer 400 from leaking into the second AlGaN layer 500, and the aluminum composition of the other second AlGaN sublayers 510 is smaller than that of the second AlGaN sublayers close to the light emitting layer 400 The aluminum composition of the nitrogen sublayer 510, that is, other second AlGaN sublayers 510 provide holes, wherein the aluminum composition of the second AlGaN sublayer 510 farthest from the light-emitting layer 400 is the smallest, which The role is to provide a high concentration of holes. The second AlGaN sublayer 510 with different aluminum composition weakens the built-in electric field of the second AlGaN layer 500, so that the pressure between the second AlGaN layer 500 and the light emitting layer 400 The electric polarization effect is weakened, which improves the effective injection rate of holes, so that the second AlGaN sublayer 510 has the functions of blocking electron leakage and increasing the hole injection rate, and improves the radiative recombination rate of electrons and holes, thereby The internal quantum rate and luminous efficiency of the AlGaN-based ultraviolet LED epitaxial structure are improved. In other embodiments, the aluminum composition of the second AlGaN sublayer 510 is 0.05-0.65, and the second AlGaN layer 500 includes four second AlGaN sublayers 510 stacked in sequence, four The second AlGaN sublayer 510 is sequentially composed of the first polarized layer, the second polarized layer, the third polarized layer and the fourth polarized layer, and the aluminum composition of the first polarized layer is 0.65, so The aluminum composition of the second polarization layer is 0.45, the aluminum composition of the third polarization layer is 0.25, and the aluminum composition of the fourth polarization layer is 0.05. The above-mentioned four-layer second AlGaN sub-layer 510 has a lower difference in aluminum composition, so that the electric field formed between two adjacent second AlGaN sub-layers 510 is more uniform, so that the second The weakening of the built-in electric field of the AlGaN layer 500 is uniform, that is, the electric field strength of the built-in electric field of the second AlGaN layer 500 is uniformly weakened sequentially, so that the built-in electric field of the second AlGaN layer 500 In the case of uniform weakening, the effective injection rate of holes is increased, so that the second AlGaN sublayer 510 has the functions of blocking electron leakage and increasing the hole injection rate, and improving the radiative recombination rate of electrons and holes, thereby improving The internal quantum rate and luminous efficiency of AlGaN-based ultraviolet LED epitaxial structure were studied.

In one embodiment, please refer to FIG. 1 , the plurality of second AlGaN sub-layers 510 have the same thickness. When the AlGaN-based ultraviolet LED epitaxial structure is energized, an electric field is formed between the surfaces of two adjacent second AlGaN sub-layers 510, and the field strength direction of this electric field is the same as that of the second AlGaN sublayer 510. The field strength direction of the built-in electric field in the nitrogen sub-layer 510 is opposite, and its effect is to weaken the built-in electric field of the second AlGaN layer 500, making it easier for holes to be injected from the second AlGaN layer 500 The light-emitting layer 400 improves the effective injection rate of holes. While the thicknesses of the plurality of second AlGaN sublayers 510 are uniform and equal, the high-concentration holes generated by the second AlGaN layers 500 pass through the second AlGaN sublayers 510 with the same thickness in sequence, Make holes travel through the second AlGaN sub-layer 510 in the same way, so that holes can pass through the second AlGaN layer 500 more easily, and the effective injection rate of holes is improved, thereby improving the efficiency of electrons. The radiative recombination rate with the holes, thereby improving the internal quantum rate and luminous rate of the AlGaN-based ultraviolet LED epitaxial structure.

In one embodiment, please refer to FIG. 1 , the thickness of the second AlGaN sublayer 510 is 20-30 nm. In this embodiment, the second AlGaN layer 500 includes four layers of the second AlGaN sublayers 510, and the materials of the second AlGaN sublayers 510 are all AlGaN, except that each The aluminum composition of the second AlGaN sublayer 510 of the layer is different. Four layers of the second AlGaN sublayers 510 are stacked in sequence, the thickness of the second AlGaN sublayers 510 in each layer is the same, and the four second AlGaN sublayers 510 have the same thickness and different aluminum components. The nitrogen sublayer 510 together constitutes the second AlGaN layer 500 . When the AlGaN-based ultraviolet LED epitaxial structure is energized, the second AlGaN layer 500 is used to generate holes, wherein the aluminum composition of the AlGaN sublayer far away from the light emitting layer 400 is The aluminum composition composition of the AlGaN sublayer close to the light emitting layer 400 is smaller than that of the AlGaN sublayer far away from the light emitting layer 400 for generating high-concentration holes, and the four layers with equal thickness The second AlGaN sublayer 510 increases the effective hole injection rate of each of the AlGaN sublayers, thereby increasing the effective hole injection rate of the AlGaN layer and improving the electron-hole ratio. The radiative recombination rate improves the internal quantum rate and luminous rate of the AlGaN-based ultraviolet LED epitaxial structure. In other embodiments, the thicknesses of the four second AlGaN sublayers 510 are equal, and each of the second AlGaN sublayers 510 has a thickness of 25 nm, so that the second AlGaN In the case of the effective hole injection rate of the layer 500, the thickness of the second AlGaN layer 500 is reduced, thereby reducing the overall thickness of the AlGaN-based ultraviolet LED epitaxial structure.

In one embodiment, please refer to FIG. 1 , the dopant atoms of the second AlGaN layer 500 include magnesium atoms. In this embodiment, the material of the second AlGaN layer 500 is P-type AlGaN, and the second AlGaN layer 500 is made by a polarization doping process. The diAlGaN layer 500 includes four layers of the second AlGaN sublayer 510, that is, the second AlGaN layer 500 includes a first polarization-doped AlGaN layer, a second polarization a doped AlGaN layer, a third polarization doped AlGaN layer, and a fourth polarization doped AlGaN layer, the first polarization doped AlGaN layer is connected to the light-emitting layer 400, and the The first polarization doped AlGaN layer, the second polarization doped AlGaN layer, the third polarization doped AlGaN layer and the fourth polarization doped AlGaN layer The aluminum component of the order decreases linearly. Since each layer of the second AlGaN layer 500 is made of the same material, that is, the first polarization-doped AlGaN layer, the second polarization-doped AlGaN layer, and the third pole The material of the polarization-doped AlGaN layer and the fourth polarization-doped AlGaN layer is P-type AlGaN, which makes doping of the second AlGaN layer 500 easier, wherein the first The atoms doped in the dialuminium-gallium-nitride layer 500 are magnesium atoms. According to the activity of the magnesium atoms is stronger than that of the aluminum atoms, the magnesium atoms also generate more holes in the mixture of the aluminum-gallium-nitride layer, so that the second aluminum-gallium-nitride layer The hole concentration provided by the nitrogen layer 500 is increased, so that the second AlGaN layer 500 can provide high-concentration holes for the light-emitting layer 400, thereby improving the hole effectiveness of the second AlGaN layer 500. The injection rate improves the radiative recombination rate of electrons and holes, thereby improving the internal quantum rate and luminous rate of the epitaxial structure of the AlGaN-based UV LED. In other embodiments, the doping atoms of the second AlGaN layer 500 also include other atoms that can generate a large number of holes, for example, the doping atoms of the second AlGaN layer 500 include gold atoms; For example, the dopant atoms of the second AlGaN layer 500 include silver atoms. The above-mentioned dopant atoms are used to increase the number of holes in the second AlGaN layer 500, so that the effective hole injection rate of the second AlGaN layer 500 increases, which facilitates the improvement of the radiative recombination of electrons and holes. rate, thereby improving the internal quantum rate and luminous rate of the AlGaN-based ultraviolet LED epitaxial structure.

In one of the embodiments, the second AlGaN layer 500 includes four P-type AlGaN layers whose aluminum composition decreases linearly in sequence, and the dopant atoms of the second AlGaN layer 500 are magnesium atoms, Its doping concentration is 1×10 ¹⁷ cm ^-3 , the substrate 100 includes a C-plane sapphire substrate 100 , the buffer layer 200 includes an undoped AlGaN layer, and the thickness of the buffer layer 200 is 1 ~2μm, the first AlGaN layer 300 is an N-type AlGaN layer, the thickness of the first AlGaN layer 300 is 1~3μm, and the light emitting layer 400 includes multiple quantum barrier layers and multiple Quantum well layer, the quantum barrier layer and the quantum well layer are stacked in sequence, the thickness of the quantum barrier layer is 8-20 μm, and the thickness of the quantum well layer is 2-7 μm. In this way, the aluminum composition of the second AlGaN sublayer close to the light-emitting layer is the largest, which is used to reduce the leakage of electrons from the light-emitting layer; the aluminum composition of the second AlGaN sublayer far away from the light-emitting layer is the smallest, used for Provide holes to the light-emitting layer; the second AlGaN sublayer with different components weakens the built-in electric field of the second AlGaN layer, making the piezoelectric polarization effect between the second AlGaN layer and the light-emitting layer weakening, thereby improving the effective injection rate of holes, so that the second AlGaN sublayer has the function of blocking electron leakage and increasing the hole injection rate, thereby increasing the radiative recombination rate of electrons and holes, and improving the AlGaN Intrinsic Quantum Rate and Luminous Efficiency of Epitaxial Structures Based on UV LEDs.

In one of the embodiments, the second AlGaN layer 500 includes four second AlGaN sublayers 510 with the same thickness, each of the second AlGaN sublayers 510 has a thickness of 20˜ 30 nm, that is, the thickness of the second AlGaN layer 500 is 80-120 nm. Wherein, the four second AlGaN sub-layers 510 are the first polarization-doped AlGaN layer, the second polarization-doped AlGaN layer, the third polarization-doped AlGaN layer, and the third polarization-doped AlGaN layer, respectively. A nitrogen layer and a fourth polarization-doped Al-GaN layer, the first polarization-doped Al-GaN layer is connected to the light-emitting layer 400 away from the first Al-GaN layer 300, and the first polarization The aluminum composition of the doped AlGaN layer is 0.65, the aluminum composition of the second polarization doped AlGaN layer is 0.45, and the aluminum composition of the third polarization doped AlGaN layer is 0.25 , the aluminum composition of the fourth polarization-doped AlGaN layer is 0.05.

In the above-mentioned AlGaN-based ultraviolet LED epitaxial structure, the aluminum component of the second AlGaN sublayer close to the light-emitting layer is the largest, which is used to reduce the leakage of electrons from the light-emitting layer; the second AlGaN sublayer far away from the light-emitting layer The smallest aluminum composition is used to provide holes to the light-emitting layer; the second Al-GaN sub-layer with different components weakens the built-in electric field of the second Al-GaN layer, so that the second Al-GaN layer and the light-emitting layer The piezoelectric polarization effect between them is weakened, thereby increasing the effective injection rate of holes, so that the second AlGaN sublayer has the functions of blocking electron leakage and increasing the hole injection rate, thereby enabling the radiative recombination of electrons and holes The rate is improved, and the internal quantum rate and luminous rate of the AlGaN-based ultraviolet LED epitaxial structure are improved.

In one embodiment, the present application also provides an ultraviolet LED lamp, including a lamp holder, a lampshade, and the AlGaN-based ultraviolet LED epitaxial structure described in any of the above-mentioned embodiments, and the AlGaN-based ultraviolet LED epitaxial structure The structure is arranged on the lamp holder, the lampshade is connected with the lamp holder, and the AlGaN-based ultraviolet LED epitaxial structure is covered.

In the above-mentioned ultraviolet LED lamp, the aluminum composition of the second AlGaN sublayer close to the light-emitting layer is the largest, which is used to reduce the leakage of electrons from the light-emitting layer; the aluminum composition of the second AlGaN sublayer far away from the light-emitting layer is The minimum is used to provide holes to the light-emitting layer; the second AlGaN sublayer with different components weakens the built-in electric field of the second AlGaN layer, making the pressure between the second AlGaN layer and the light-emitting layer The electric polarization effect is weakened, thereby increasing the effective injection rate of holes, so that the second AlGaN sublayer has the functions of blocking electron leakage and increasing the hole injection rate, thereby increasing the radiative recombination rate of electrons and holes, improving The internal quantum rate and luminous efficiency of the AlGaN-based ultraviolet LED epitaxial structure are improved, that is, the luminous efficiency of the ultraviolet LED lamp is improved.

The various technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the various technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. An AlGaN-based ultraviolet LED epitaxial structure, characterized in that it comprises: a substrate, a buffer layer, a first AlGaN layer, a light-emitting layer and a second AlGaN layer which are sequentially stacked, and the first The AlGaN layer is used to provide electrons, the second AlGaN layer is used to provide holes, and the light-emitting layer is used for radiation recombination of electrons and holes to emit light; The second AlGaN layer includes a plurality of second AlGaN sublayers, the plurality of second AlGaN sublayers are stacked in sequence, and the aluminum components of the plurality of second AlGaN sublayers are different , the aluminum composition of the second AlGaN sublayer connected to the light emitting layer is greater than the aluminum composition of other second AlGaN sublayers. 2. The AlGaN-based ultraviolet LED epitaxial structure according to claim 1, characterized in that, from close to the light-emitting layer to away from the light-emitting layer, the aluminum group of each second AlGaN sublayer points decrease sequentially. 3. The AlGaN-based ultraviolet LED epitaxial structure according to claim 2, characterized in that, from close to the light-emitting layer to far away from the light-emitting layer, the aluminum group of each second AlGaN sublayer decrease linearly. 4 . The AlGaN-based ultraviolet LED epitaxial structure according to claim 2 , wherein the aluminum composition of the second AlGaN sublayer is 0-0.8. 5 . The AlGaN-based ultraviolet LED epitaxial structure according to claim 4 , wherein the aluminum composition of the second AlGaN sublayer is 0.05˜0.65. 6 . The AlGaN-based ultraviolet LED epitaxial structure according to claim 1 , wherein the plurality of second AlGaN sub-layers have the same thickness. 7 . The AlGaN-based ultraviolet LED epitaxial structure according to claim 6 , wherein the thickness of the second AlGaN sublayer is 20-30 nm. 8 . The AlGaN-based ultraviolet LED epitaxial structure according to claim 1 , wherein the doping atoms of the second AlGaN layer include magnesium atoms. 9 . The AlGaN-based ultraviolet LED epitaxial structure according to claim 8 , wherein the doping concentration of magnesium atoms in the second AlGaN layer is 1×10 ¹⁷ cm ⁻³ . 10. An ultraviolet LED lamp, characterized in that it comprises a lamp holder, a lampshade, and the AlGaN-based ultraviolet LED epitaxial structure as claimed in any one of claims 1 to 9, the AlGaN-based ultraviolet LED epitaxial structure It is arranged on the lamp holder, the lampshade is connected with the lamp holder, and the AlGaN-based ultraviolet LED epitaxial structure is covered.