CN113394319A - Deep ultraviolet light-emitting element and preparation method thereof - Google Patents
Deep ultraviolet light-emitting element and preparation method thereof Download PDFInfo
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Abstract
The invention provides a deep ultraviolet light-emitting element and a preparation method thereof, wherein the deep ultraviolet light-emitting element comprises: the epitaxial layer comprises a substrate and an epitaxial layer located on the substrate, wherein the epitaxial layer sequentially comprises from bottom to top: the light-emitting diode comprises a first n-type semiconductor layer, blocking layers, a quantum well layer and a P-type semiconductor layer, wherein the blocking layers comprise at least two hole blocking layers and a second n-type semiconductor layer between every two adjacent hole blocking layers. According to the invention, the blocking layer is additionally arranged between the first n-type semiconductor layer and the quantum well layer, so that the distribution of electron and hole wave functions in the quantum well layer can be regulated and controlled, the diffusion transition of a p-type hole to the first n-type semiconductor layer is reduced, meanwhile, the concentration difference degree of the electron and the hole of the quantum well layer can be reduced, the overlapping and recombination probability of the electron wave functions of the electron and the hole in the quantum well layer is improved, the quantum conversion efficiency of the deep ultraviolet light-emitting element is further improved, and the light-emitting efficiency of the deep ultraviolet light-emitting element is improved to 5% -10%.
Description
Technical Field
The invention relates to the technical field of semiconductor chips, in particular to a deep ultraviolet light-emitting element and a preparation method thereof.
Background
The deep ultraviolet light emitting element has a wavelength range of 200-300 nm, can interrupt DNA or RNA of viruses and bacteria by the emitted deep ultraviolet light, directly kills the viruses and the bacteria, and can be widely applied to the sterilization and disinfection fields of air purification, tap water sterilization, household air conditioner sterilization, automobile air conditioner sterilization and the like.
The p-type semiconductor layer of the deep ultraviolet light-emitting element uses AlGaN with high Al composition, and as the Al composition rises, the doping and ionization efficiency of Mg is reduced, so that the hole concentration of the deep ultraviolet light-emitting element is generally lower than 1E17cm-2The n-type semiconductor layer is doped with Si, the doping and ionization efficiency of the Si is high, and the electron concentration is generally higher than 5E18cm-2. Due to the fact that the difference between the hole concentration and the electron concentration of the p-type semiconductor layer and the n-type semiconductor layer is large, the electron concentration injected into the quantum well layer is far higher than the hole concentration, the distribution of electron-hole wave functions in the space of the quantum well layer is extremely inconsistent, and the electron-hole recombination efficiency is low. Under the condition of large-current injection, redundant electrons overflow the quantum well layer and leak to the p-type semiconductor layer, and further generate non-radiative recombination with holes, and further the luminous efficiency is rapidly reduced. Therefore, the large concentration difference and the uneven distribution of the electrons and the holes in the deep ultraviolet light-emitting element are important reasons for the light-emitting efficiency of the deep ultraviolet light-emitting element to be generally lower than 5%.
Disclosure of Invention
The invention aims to provide a deep ultraviolet light-emitting element and a preparation method thereof, which are used for solving the problems of large concentration difference and uneven distribution of electrons and holes in the deep ultraviolet light-emitting element.
In order to achieve the above and other related objects, the present invention provides a deep ultraviolet light emitting element comprising: the epitaxial layer comprises a substrate and an epitaxial layer located on the substrate, wherein the epitaxial layer sequentially comprises from bottom to top: the light-emitting diode comprises a first n-type semiconductor layer, blocking layers, a quantum well layer and a P-type semiconductor layer, wherein the blocking layers comprise at least two hole blocking layers and a second n-type semiconductor layer between every two adjacent hole blocking layers.
Optionally, in the deep ultraviolet light emitting element, the blocking layer is a sandwich structure layer, and includes a first hole blocking layer, a second n-type semiconductor layer, and a second hole blocking layer that are stacked.
Optionally, in the deep ultraviolet light emitting element, the first hole blocking layer has a thickness of
Optionally, in the deep ultraviolet light emitting element, the second hole blocking layer has a thickness of
Optionally, in the deep ultraviolet light emitting device, the thickness of the second n-type semiconductor layer is 50nm to 200 nm.
Optionally, in the deep ultraviolet light emitting element, the hole blocking layer is made of at least one of AlGaN and AlN.
Optionally, in the deep ultraviolet light emitting element, an Al component content in a material of the hole blocking layer is greater than 90%.
Optionally, in the deep ultraviolet light emitting element, a material of the second n-type semiconductor layer includes AlGaN.
Optionally, in the deep ultraviolet light emitting device, the Al component content in the material of the second n-type semiconductor layer is the same as that in the first n-type semiconductor layer.
Optionally, in the deep ultraviolet light emitting element, the Al component content in the material of the second n-type semiconductor layer is 50% to 75%.
Optionally, in the deep ultraviolet light emitting device, the first n-type semiconductor layer material is doped with Si, and the Si doping concentration is 8E18cm-3～5E19cm-3。
Optionally, in the deep ultraviolet light emitting element, the second n-type semiconductor layer is doped with Si, and the Si doping concentration in the second n-type semiconductor layer is 1.6% to 62.5% of the Si doping concentration in the first n-type semiconductor layer.
Optionally, in the deep ultraviolet light emitting device, the Si doping concentration in the material of the second n-type semiconductor layer is 8E17cm-3～5E18cm-3。
Optionally, in the deep ultraviolet light emitting element, the P-type semiconductor layer includes a P-type electron blocking layer and a P-type contact layer on the P-type electron blocking layer.
Optionally, in the deep ultraviolet light emitting element, the p-type electron blocking layer is made of AlGaN.
Optionally, in the deep ultraviolet light emitting device, a material of the p-type contact layer includes at least one of AlGaN and GaN.
Optionally, in the deep ultraviolet light emitting device, the epitaxial layer further includes an AlN layer located between the substrate and the first n-type semiconductor layer.
In order to achieve the above objects and other related objects, the present invention also provides a method for manufacturing a deep ultraviolet light emitting device, including:
providing a substrate;
forming an epitaxial layer on the substrate, wherein the epitaxial layer sequentially comprises from bottom to top: the light-emitting diode comprises a first n-type semiconductor layer, blocking layers, a quantum well layer and a P-type semiconductor layer, wherein the blocking layers comprise at least two hole blocking layers and a second n-type semiconductor layer between every two adjacent hole blocking layers.
Optionally, in the preparation method of the deep ultraviolet light emitting element, the blocking layer is a sandwich structure layer, and includes a first hole blocking layer, a second n-type semiconductor layer, and a second hole blocking layer, which are stacked.
Optionally, in the preparation method of the deep ultraviolet light emitting element, the thickness of the first hole blocking layer is
Optionally, in the preparation method of the deep ultraviolet light emitting element, the thickness of the second hole blocking layer is
Optionally, in the method for manufacturing the deep ultraviolet light emitting device, the thickness of the second n-type semiconductor layer is 50nm to 200 nm.
Optionally, in the preparation method of the deep ultraviolet light emitting element, the material of the hole blocking layer is at least one of AlGaN and AlN.
Optionally, in the preparation method of the deep ultraviolet light emitting element, the content of the Al component in the material of the hole blocking layer is greater than 90%.
Optionally, in the preparation method of the deep ultraviolet light emitting element, a material of the second n-type semiconductor layer includes AlGaN.
Optionally, in the preparation method of the deep ultraviolet light emitting device, the Al component content in the material of the second n-type semiconductor layer is the same as that in the material of the first n-type semiconductor layer.
Optionally, in the preparation method of the deep ultraviolet light emitting element, the Al component content in the material of the second n-type semiconductor layer is 50% to 75%.
Optionally, in the preparation method of the deep ultraviolet light emitting device, the first n-type semiconductor layer material is doped with Si, and the Si doping concentration is 8E18cm-3～5E19cm-3。
Optionally, in the preparation method of the deep ultraviolet light emitting element, the second n-type semiconductor layer is doped with Si, and the Si doping concentration in the second n-type semiconductor layer is 1.6% to 62.5% of the Si doping concentration in the first n-type semiconductor layer.
Optionally, in the preparation method of the deep ultraviolet light emitting device, the Si doping concentration in the material of the second n-type semiconductor layer is 8E17cm-3～5E18cm-3。
Optionally, in the preparation method of the deep ultraviolet light emitting element, the P-type semiconductor layer includes a P-type electron blocking layer and a P-type contact layer located on the P-type electron blocking layer.
Optionally, in the preparation method of the deep ultraviolet light emitting element, the material of the p-type electron blocking layer includes AlGaN.
Optionally, in the preparation method of the deep ultraviolet light emitting element, a material of the p-type contact layer includes at least one of AlGaN and GaN.
Optionally, in the method for manufacturing a deep ultraviolet light emitting device, the epitaxial layer further includes an AlN layer located between the substrate and the first n-type semiconductor layer.
Optionally, in the preparation method of the deep ultraviolet light emitting element, a process for forming the first n-type semiconductor layer, the blocking layer, the quantum well layer, and the p-type semiconductor layer is any one of an MOCVD process, a molecular beam epitaxy process, an HVPE process, a plasma-assisted chemical vapor deposition, and a sputtering method.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
according to the invention, the blocking layer is additionally arranged between the first n-type semiconductor layer and the quantum well layer, so that the distribution of electron hole wave functions in the quantum well layer can be regulated and controlled, the diffusion transition of p-type holes to the first n-type semiconductor layer is reduced, meanwhile, the high electron barrier formed by the blocking layer can reduce the injection efficiency of electrons to the quantum well layer, the difference degree of electrons and holes of the quantum well layer is reduced, the overlapping and recombination probability of the electron wave functions of the electrons and the holes in the quantum well layer is improved, the quantum conversion efficiency of the deep ultraviolet light-emitting element is further improved, and the light-emitting efficiency of the deep ultraviolet light-emitting element is improved to 5% -10%.
Drawings
Fig. 1 is a schematic structural diagram of an ultraviolet semiconductor light emitting device according to an embodiment of the present invention;
fig. 2 is a flowchart of a method for manufacturing an ultraviolet semiconductor light emitting element according to an embodiment of the present invention;
wherein, in fig. 1 to 2:
100-substrate, 101-first n-type semiconductor layer, 102-blocking layer, 1021-first hole blocking layer, 1022-second n-type semiconductor layer, 1023-second hole blocking layer, 103-quantum well layer, 104-p type semiconductor layer, 1041-p type electron blocking layer, 1042-p type contact layer, 105-AlN layer.
Detailed Description
In the deep ultraviolet light-emitting element in the prior art, the difference between the hole concentration and the electron concentration of a p-type semiconductor layer and an n-type semiconductor layer is large, so that the electron concentration injected into a quantum well layer is far higher than the hole concentration, further, the distribution of an electron hole wave function in the space of the quantum well layer is extremely inconsistent, and the electron hole recombination efficiency is low. In the case of high current injection, excess electrons overflow the quantum well layer, leak to the p-type semiconductor layer, and are non-radiatively recombined with holes, which further causes a rapid decrease in light emission efficiency. Therefore, the large concentration difference and the uneven distribution of the electrons and the holes in the deep ultraviolet light-emitting element are important reasons for the light-emitting efficiency of the deep ultraviolet light-emitting element to be generally lower than 5%.
In order to solve the problems of large concentration difference and uneven distribution of electrons and holes in an ultraviolet semiconductor light-emitting element, the invention provides the ultraviolet semiconductor light-emitting element, a hole blocking layer is added between a first n-type semiconductor layer and a quantum well layer, so that the diffusion transition of p-type holes to the first n-type semiconductor layer can be reduced, meanwhile, a high electron barrier is formed, the injection efficiency of electrons to the quantum well layer can be reduced, the concentration difference degree of electrons and holes of the quantum well layer is reduced, the overlapping recombination probability of electron wave functions of the electrons and the holes in the quantum well layer is improved, and further, the quantum conversion efficiency of the deep ultraviolet semiconductor light-emitting element is improved.
Before describing embodiments according to the present invention, the following description will be made in advance. First, in the present specification, the Al composition ratio is not explicitly given, and when only "AlGaN" is given, it means that the chemical composition ratio of the group III element (the sum of Al and Ga) to N is 1: 1, any compound having an unfixed ratio of the group III element Al to Ga. Note that, when only denoted by "AlN" or "GaN", Ga and Al are not included in the composition ratio, but are not excluded by the mere designation of "AlGaN". The value of the Al composition ratio can be measured by photoluminescence measurement, X-ray diffraction measurement, or the like.
In this specification, a layer that electrically functions as a p-type layer is referred to as a p-type layer, and a layer that electrically functions as an n-type layer is referred to as an n-type layer. On the other hand, when a specific impurity such as Mg or Si is not particularly added and does not electrically function as a p-type or an n-type, it is referred to as "i-type" or "undoped". The undoped layer may be mixed with impurities inevitable in the manufacturing process, and specifically, when the carrier density is small (for example, less than 4 × 10/cm), it is referred to as "undoped" in the present specification. The values of the concentrations of impurities such as Mg and Si were obtained by SIMS analysis.
The deep ultraviolet light emitting device and the method for manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings and specific examples. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
Referring to fig. 1, the deep ultraviolet light emitting device provided in this embodiment includes: the substrate 100 and lie in epitaxial layer on the substrate 100, the epitaxial layer includes from bottom to top in proper order: a first n-type semiconductor layer 101, a blocking layer 102, a quantum well layer 103, and a P-type semiconductor layer 104. The blocking layer 102 includes at least two hole blocking layers and a second n-type semiconductor layer between each two adjacent hole blocking layers.
As the substrate 100, a substrate which can transmit light emitted from the quantum well layer 103 and emit deep ultraviolet light from the substrate side is preferably used, and for example, a sapphire substrate, a single crystal AlN substrate, or the like can be used. As the substrate 100, an AlN template substrate in which an undoped AlN structure layer is epitaxially grown on the surface of a sapphire substrate may be used. In order to improve the light extraction efficiency, the light exit side of the substrate 100 or the opposite side thereof, or the surface of the AlN structure layer of the AlN template substrate may be in a concave-convex shape. In order to reduce the dislocation of the AlN structure layer, high-temperature (for example, 1500 ℃ or higher) annealing treatment may be performed.
An AlN layer 105 may be disposed between the substrate 100 and the first n-type semiconductor layer 101. The AlN layer 105 may serve as a buffer layer for mitigating lattice mismatch between the substrate 100 and the first n-type semiconductor layer 101. Of course, the AlN layer 105 may also serve as an unintentional doping layer or the like.
The first n-type semiconductor layer 101 may be provided on the substrate 100 via the AlN layer 105 as needed, or the first n-type semiconductor layer 101 may be provided directly on the substrate 100. The first n-type semiconductor layer 101 may be a conventional n-type layer, and may be formed of n-AlGaN, for example. The first n-type semiconductor layer 101 functions as an n-type layer by doping an n-type dopant, and specific examples of the n-type dopant include, but are not limited to, silicon (Si), germanium (Ge), tin (Sn), sulfur (S), oxygen (O), titanium (Ti), zirconium (Zr), and the like. The dopant concentration of the n-type dopant may be a dopant concentration at which the first n-type semiconductor layer 101 can function as an n-type layer. Further, the n-type dopant in the first n-type semiconductor layer 101 is preferably Si, and the doping concentration of Si is preferably 8E18cm-3～5E19cm-3. The first n-type semiconductor layer 101 preferably has a band gap wider than that of the quantum well layer 103 (a well layer in the case of a multiple quantum well structure) and has a transmittance for deep ultraviolet light to be emitted. The first n-type semiconductor layer 101 may have a single-layer structure or a multi-layer structure, or may have a superlattice structure.
The blocking layer 102 includes at least two hole blocking layers and a second n-type semiconductor layer between each two adjacent hole blocking layers. The blocking layer 102 may include two spatial blocking layers and one second n-type semiconductor layer, or may include three spatial blocking layers and two second n-type semiconductor layers. For example, the blocking layer 102 includes a first hole blocking layer, a second n-type semiconductor layer, and a second hole blocking layer in this order; for another example, the blocking layer 102 includes a first hole blocking layer, a second n-type semiconductor layer, a second hole blocking layer, a second n-type semiconductor layer, and a first hole blocking layer in sequence. The first hole blocking layer and the second hole blocking layer may be identical or may not be identical, for example, at least one of the material, Al composition, and thickness may be different. Of course, the blocking layer 102 may also include four layers and five layers of space blocking layers, and the second n-type semiconductor layer is also added accordingly, which is not described herein.
Preferably, the blocking layer 102 is a sandwich structure, and includes a first hole blocking layer 1021, a second n-type semiconductor layer 1022, and a second hole blocking layer 1023, which are sequentially stacked, as shown in fig. 1. The following embodiments are described in detail with the blocking layer 102 as a sandwich structure.
The blocking layer 102 includes a first hole blocking layer 1021, a second n-type semiconductor layer 1022, and a second hole blocking layer 1023 stacked on the first n-type semiconductor layer 101. The material of each of the first hole blocking layer 1021 and the second hole blocking layer 1023 may be at least one of AlGaN and AlN, that is, the material of the first hole blocking layer 1021 may be the same as or different from that of the second hole blocking layer 1023. For example, the first hole blocking layer 1021 is made of AlGaN, and the second hole blocking layer 1023 is made of AlN. The Al component content in the material of each of the first hole blocking layer 1021 and the second hole blocking layer 1023 is greater than 90%, and the Al component content in the material of each of the first hole blocking layer 1021 and the second hole blocking layer 1023 may be the same or different. For example, the first hole blocking layer 1021 and the second hole blocking layer 1023 are made of AlGaN, and the Al content is 95%. For another example, the first hole blocking layer 1021 is made of AlGaN, the Al content is 95%, and the second hole blocking layer 1023 is made of AlN.
Since the first hole blocking layer 1021 and the second hole blocking layer 1023 are high-Al-composition structural layers and have relatively high electron barriers, electrons in the first n-type semiconductor layer 101 need more energy to enter the quantum well layer 103, and therefore, the injection efficiency of electrons into the quantum well layer 103 can be reduced by the first hole blocking layer 1021 and the second hole blocking layer 1023. It is known from the boltzmann distribution or dirac distribution that holes may transit to the first n-type semiconductor layer 101 with a certain probability, and the sandwich structure composed of the first hole blocking layer 1021, the second n-type semiconductor layer 1022, and the second hole blocking layer 1023 can reduce the diffusion transition of p-type holes to the first n-type semiconductor layer 101 by a high barrier and band control, thereby increasing the injection efficiency of p-type holes. According to the above analysis, the blocking layer 102, i.e., the sandwich structure of the first hole blocking layer 1021, the second n-type semiconductor layer 1022 and the second hole blocking layer 1023, can alleviate the concentration difference degree and the non-uniform distribution of electrons and holes in the quantum well layer 103.
Since AlGaN is a high-resistance material, the higher the Al composition, the higher the electron ionization energy, the higher the resistance value, and the higher the voltage, the thickness of the first hole blocking layer 1021 and the second hole blocking layer 1023 cannot be too thick to exceed a designed value, otherwise, the first hole blocking layer 1021 and/or the second hole blocking layer 1023 are too thick, which may cause problems such as a sharp increase in resistance value and a high voltage increase. The thickness (design value) of the first hole blocking layer 1021 is preferably set to be thick
The thickness (design value) of the second hole blocking layer 1023 is preferably set to be thick
The second n-type semiconductor layer 1022 serves to control the concentration of electrons injected into the quantum well layer 103, and current spreading. The material of the second n-type semiconductor layer 1022 includes, but is not limited to, AlGaN. Al component in the material of the second n-type semiconductor layer 1022The content may be the same as or different from that of the first n-type semiconductor layer 101. Preferably, the second n-type semiconductor layer 1022 is made of the same material as the first n-type semiconductor layer 101 in Al content. The Al component content in the material of the second n-type semiconductor layer 1022 is preferably 50% to 75%. The second n-type semiconductor layer 1022 is doped with an n-type dopant, which may be, but not limited to, silicon (Si), germanium (Ge), tin (Sn), sulfur (S), oxygen (O), titanium (Ti), zirconium (Zr), or the like. Further, the n-type dopant is preferably Si, and the doping concentration of Si in the second n-type semiconductor layer 1022 is much lower than that of the first n-type semiconductor layer 101, so as to achieve the effects of controlling the concentration of electrons injected into the quantum well layer 103 and improving the lateral current spreading of the first n-type AlGaN layer 101. Further, the Si doping concentration in the second n-type semiconductor layer 1022 is 1.6% to 62.5% of the Si doping concentration of the first n-type semiconductor layer 101. Preferably, the doping concentration of Si in the material of the second n-type semiconductor layer 1022 is 8E17cm-3～5E18cm-3. The thickness of the second n-type semiconductor layer 1022 is preferably 50nm to 200 nm.
The quantum well layer 103 is disposed on the blocking layer 102. The Quantum Well layer 103 may have a single-layer structure, and preferably has a multi-Quantum Well (MQW) structure in which a Well layer and a barrier layer made of AlGaN having different Al composition ratios are stacked. In the case of the single-layer structure, the layer emitting deep ultraviolet light is the quantum well layer itself, and in the case of the multiple quantum well structure, the layer emitting deep ultraviolet light is the well layer. The quantum well layer 103 is a conventional structure and will not be described herein.
A p-type semiconductor layer 104 disposed on the quantum well layer 103, and the p-type semiconductor layer 104 may include a p-type electron blocking layer 1041 and a p-type contact layer 1042. The p-type electron blocking layer 1041 is used for blocking electrons, preventing the electrons from overflowing to the p-type contact layer 1042, and further injecting the electrons into the quantum well layer 103, so as to reduce the occurrence of non-radiative recombination and further improve the light emitting efficiency of the deep ultraviolet light emitting device.
The p-type electron blocking layer 1041 is preferably made of AlGaN, but is not limited thereto. The thickness of the p-type electron blocking layer 1041 is not particularly limited. The thickness of the p-type electron blocking layer 1041 is preferably larger than the thickness of the barrier layer. Examples of the p-type dopant doped into the p-type electron blocking layer 1041 include, but are not limited to, magnesium (Mg), zinc (Zn), calcium (Ca), beryllium (Be), and manganese (Mn). The p-type dopant is preferably Mg. The dopant concentration of the p-type electron blocking layer 1041 is not particularly limited as long as it can function as a p-type semiconductor layer.
The p-type contact layer 1042 is disposed on the p-type electron blocking layer 1041. The p-type contact layer 1042 is a layer for reducing contact resistance between a p-side electrode disposed directly above it and the p-type electron blocking layer 1041. The material of the p-type contact layer 1042 includes at least one of AlGaN and GaN, but is not limited thereto. As the p-type contact layer of the deep ultraviolet light emitting element, a p-type GaN layer which is easy to increase the hole concentration is generally used, and a p-type AlGaN layer may be used, and although the hole concentration may be slightly decreased in the AlGaN layer compared to the GaN layer, the deep ultraviolet light emitted from the light emitting layer can transmit through the p-type AlGaN layer, so that the light extraction efficiency of the whole deep ultraviolet light emitting element is improved, and the light emission output of the deep ultraviolet light emitting element can be improved.
Compared with the existing deep ultraviolet light-emitting element, the embodiment has the blocking layer between the first n-type semiconductor layer and the quantum well layer, the structure can regulate and control the distribution of electron hole wave functions in the quantum well layer, the diffusion transition of a p-type hole to the first n-type semiconductor layer can be reduced, meanwhile, the blocking layer structure forms a high electron barrier, the injection efficiency of electrons to the quantum well layer can be reduced, the difference degree of the electron holes of the quantum well layer is reduced, the overlapping and recombination probability of the electron wave functions of the electron and the hole in the quantum well layer is improved, the quantum conversion efficiency of the deep ultraviolet light-emitting element is finally improved, and the light-emitting efficiency of the deep ultraviolet light-emitting element is improved to 5% -10%.
In addition, the invention also provides a preparation method of the deep ultraviolet light-emitting element, which specifically comprises the following steps:
step S0: providing a substrate;
step S1: forming an epitaxial layer on the substrate, wherein the epitaxial layer sequentially comprises from bottom to top: the light-emitting diode comprises a first n-type semiconductor layer, blocking layers, a quantum well layer and a P-type semiconductor layer, wherein the blocking layers comprise at least two hole blocking layers and a second n-type semiconductor layer between every two adjacent hole blocking layers.
Preferably, the blocking layer is of a sandwich structure and comprises a first hole blocking layer, a second n-type semiconductor layer and a second hole blocking layer which are sequentially stacked.
A buffer layer may be further disposed between the substrate and the first n-type semiconductor layer to mitigate lattice mismatch between the substrate and the first n-type semiconductor layer. As the buffer layer, an undoped group III nitride semiconductor layer, such as an AlN layer, can be used.
The p-type semiconductor layer comprises a p-type electron blocking layer and a p-type contact layer, the p-type electron blocking layer is used for blocking electrons, and the p-type contact layer is used for reducing contact resistance between a p-side electrode arranged right above the p-type contact layer and the p-type electron blocking layer.
Referring to fig. 2, the process of forming the epitaxial layer specifically includes:
step S11: forming a buffer layer on the substrate;
step S12: forming a first n-type semiconductor layer on the buffer layer;
step S13: forming a blocking layer on the first n-type semiconductor layer;
step S14: forming a quantum well layer on the blocking layer;
step S15: and forming a p-type semiconductor layer on the quantum well layer.
In step S13, when the blocking layer is a sandwich structure and includes a first hole blocking layer, a second n-type semiconductor layer, and a second hole blocking layer that are sequentially stacked, a specific process of forming the blocking layer on the first n-type semiconductor layer includes:
step S131: forming a first hole blocking layer on the first n-type semiconductor layer;
step S132: forming a second n-type semiconductor layer on the first hole blocking layer;
step S133: and forming a second hole blocking layer on the second n-type semiconductor layer.
In the above-described manufacturing method, the deep ultraviolet light emitting element may be formed by a known thin film growth method such as a MetAl Organic ChemicAl Vapor Deposition (MOCVD) method, a Molecular Beam Epitaxy (MBE) method, an HVPE (Hydride Vapor Phase Epitaxy) method, a plasma assisted ChemicAl Vapor Deposition (PCVD), a sputtering method, and the buffer layer, the first n-type semiconductor layer, the first hole stopper layer, the second n-type semiconductor layer, the second hole stopper layer, the quantum well layer, and the p-type semiconductor layer may be formed by an MOCVD method, for example.
Compared with the technical scheme of the existing deep ultraviolet light-emitting element, the blocking layer structure is arranged between the first n-type semiconductor layer and the quantum well layer, the blocking layer structure can regulate and control the distribution of electron hole wave functions in the quantum well layer, the diffusion transition of p-type holes to the first n-type semiconductor layer can be reduced, meanwhile, a high electron barrier formed by the blocking layer structure can reduce the injection efficiency of electrons to the quantum well layer, the concentration difference degree of electrons and holes of the quantum well layer is reduced, the overlapping and recombination probability of the electron wave functions of the electrons and the holes in the quantum well layer is improved, the quantum conversion efficiency of the deep ultraviolet light-emitting element is finally improved, and the light-emitting efficiency of the deep ultraviolet light-emitting element is improved to 5% -10%.
In addition, it is to be understood that while the present invention has been described in conjunction with the preferred embodiments thereof, it is not intended to limit the invention to those embodiments. It will be apparent to those skilled in the art from this disclosure that many changes and modifications can be made, or equivalents modified, in the embodiments of the invention without departing from the scope of the invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the scope of the protection of the technical solution of the present invention, unless the contents of the technical solution of the present invention are departed.
It is to be further understood that the present invention is not limited to the particular methodology, compounds, materials, manufacturing techniques, uses, and applications described herein, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. It must be noted that, as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a step" means a reference to one or more steps and may include sub-steps. All conjunctions used should be understood in the broadest sense. Thus, the word "or" should be understood to have the definition of a logical "or" rather than the definition of a logical "exclusive or" unless the context clearly dictates otherwise. Structures described herein are to be understood as also referring to functional equivalents of such structures. Language that can be construed as approximate should be understood as such unless the context clearly dictates otherwise.
Claims (35)
1. A deep ultraviolet light emitting element, comprising: the epitaxial layer comprises a substrate and an epitaxial layer located on the substrate, wherein the epitaxial layer sequentially comprises from bottom to top: the light-emitting diode comprises a first n-type semiconductor layer, blocking layers, a quantum well layer and a P-type semiconductor layer, wherein the blocking layers comprise at least two hole blocking layers and a second n-type semiconductor layer between every two adjacent hole blocking layers.
2. The deep ultraviolet light emitting device of claim 1, wherein the blocking layer is a sandwich structure layer comprising a first hole blocking layer, a second n-type semiconductor layer and a second hole blocking layer stacked one on another.
3. The deep ultraviolet light-emitting element according to claim 2, wherein the first hole-blocking layer has a thickness of
4. The deep ultraviolet light-emitting element according to claim 2, wherein the second hole-blocking layer has a thickness of
5. The deep ultraviolet light-emitting element according to claim 2, wherein the thickness of the second n-type semiconductor layer is 50nm to 200 nm.
6. The deep ultraviolet light emitting element according to claim 1, wherein a material of the hole stopper layer is at least one of AlGaN and AlN.
7. The deep ultraviolet light-emitting element according to claim 6, wherein the hole-blocking layer is made of a material having an Al component content of more than 90%.
8. The deep ultraviolet light emitting element according to claim 1, wherein a material of the second n-type semiconductor layer includes AlGaN.
9. The deep ultraviolet light-emitting element according to claim 8, wherein the second n-type semiconductor layer is made of a material having the same Al component content as the first n-type semiconductor layer.
10. The deep ultraviolet light emitting element according to claim 8, wherein an Al component content in a material of the second n-type semiconductor layer is 50% to 75%.
11. The deep ultraviolet light emitting device of claim 1, wherein the first n-type semiconductor layer is doped with Si, and the Si doping concentration is 8E18cm-3～5E19cm-3。
12. The deep ultraviolet light emitting element according to claim 11, wherein the second n-type semiconductor layer is doped with Si, and a Si doping concentration in the second n-type semiconductor layer is 1.6% to 62.5% of a Si doping concentration of the first n-type semiconductor layer.
13. The deep ultraviolet light-emitting element according to claim 12, wherein the second n-type semiconductor layer is formed of a material having a Si doping concentration of 8E17cm-3～5E18cm-3。
14. The deep ultraviolet light emitting element according to claim 1, wherein the P-type semiconductor layer comprises a P-type electron blocking layer and a P-type contact layer on the P-type electron blocking layer.
15. The deep ultraviolet light emitting element of claim 14, wherein the p-type electron blocking layer comprises AlGaN.
16. The deep ultraviolet light emitting element according to claim 14, wherein a material of the p-type contact layer includes at least one of AlGaN and GaN.
17. The deep ultraviolet light emitting element of claim 1, wherein the epitaxial layer further comprises an AlN layer between the substrate and the first n-type semiconductor layer.
18. A method for manufacturing a deep ultraviolet light-emitting element is characterized by comprising the following steps:
providing a substrate;
forming an epitaxial layer on the substrate, wherein the epitaxial layer sequentially comprises from bottom to top: the light-emitting diode comprises a first n-type semiconductor layer, blocking layers, a quantum well layer and a P-type semiconductor layer, wherein the blocking layers comprise at least two hole blocking layers and a second n-type semiconductor layer between every two adjacent hole blocking layers.
19. The method according to claim 18, wherein the blocking layer is a sandwich structure layer comprising a first hole blocking layer, a second n-type semiconductor layer, and a second hole blocking layer stacked on the first n-type semiconductor layer.
20. The method according to claim 19, wherein the first hole blocking layer has a thickness of
21. The method according to claim 19, wherein the second hole blocking layer has a thickness of
22. The method according to claim 19, wherein the second n-type semiconductor layer has a thickness of 50nm to 200 nm.
23. The method according to claim 18, wherein the hole stopper is made of at least one of AlGaN and AlN.
24. The method according to claim 23, wherein the hole blocking layer comprises a material having an Al content of more than 90%.
25. The method according to claim 18, wherein the second n-type semiconductor layer comprises AlGaN.
26. The method according to claim 25, wherein the second n-type semiconductor layer is made of a material having the same Al content as the first n-type semiconductor layer.
27. The method according to claim 25, wherein the second n-type semiconductor layer has an Al content of 50% to 75% in a material thereof.
28. The method according to claim 18, wherein the first n-type semiconductor layer is doped with Si, and the Si doping concentration is 8E18cm-3～5E19cm-3。
29. The method according to claim 28, wherein the second n-type semiconductor layer is doped with Si, and wherein a doping concentration of Si in the second n-type semiconductor layer is 1.6% to 62.5% of a doping concentration of Si in the first n-type semiconductor layer.
30. The method according to claim 29, wherein the second n-type semiconductor layer has a Si doping concentration of 8E17cm-3～5E18cm-3。
31. The method according to claim 18, wherein the P-type semiconductor layer comprises a P-type electron blocking layer and a P-type contact layer on the P-type electron blocking layer.
32. The method according to claim 31, wherein the p-type electron blocking layer comprises AlGaN.
33. The method according to claim 31, wherein the p-type contact layer comprises at least one of AlGaN and GaN.
34. The method of claim 18, wherein the epitaxial layer further comprises an AlN layer between the substrate and the first n-type semiconductor layer.
35. The method of manufacturing the deep ultraviolet light emitting element according to claim 18, wherein a process of forming the first n-type semiconductor layer, the blocking layer, the quantum well layer, and the p-type semiconductor layer is any one of an MOCVD process, a molecular beam epitaxy process, an HVPE process, a plasma-assisted chemical vapor deposition, and a sputtering method.
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