Ultraviolet light-emitting diode epitaxial wafer with electron transport layer and preparation method thereof

Abstract

The present disclosure provides an ultraviolet light-emitting diode epitaxial wafer with an electron transport layer and a preparation method thereof, which belongs to the technical field of light-emitting diodes. An electron transport layer is added between the light-emitting layer and the n-type AlGaN layer, and the electron transport layer includes a BN / n‑AlGaN / graphene superlattice, and the BN sublayer increases the barrier height and improves the uniformity of light emission; and the radius of the B atoms in the BN sublayer is small, which reduces the defects that extend into the light-emitting layer. The n‑AlGaN sublayer provides electrons to increase the concentration of electrons that can enter the light-emitting layer. The graphene sublayer can isolate defects from the light-emitting layer and reduce defects in the light-emitting layer. The luminous efficiency and uniformity of the obtained ultraviolet light-emitting diode can be improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of light emitting diodes, and in particular to an ultraviolet light emitting diode epitaxial wafer with an electron transport layer and a preparation method thereof. Background Art

[0002] With the development of LED applications, the market demand for UV LEDs is growing. UV LEDs with a wavelength of 210-400nm have advantages that traditional UV light sources cannot match. UV LEDs are often used in lighting, biomedicine, anti-counterfeiting identification, air and water purification, biochemical testing, high-density information storage, etc.

[0003] In recent years, AlGaN-based high-brightness ultraviolet light-emitting diodes have been developed. The basic structure of the epitaxial wafer of AlGaN-based ultraviolet light-emitting diodes is usually a substrate and a buffer layer, an n-type AlGaN layer, a light-emitting layer and a p-type AlGaN layer deposited on the substrate in sequence. Carriers enter the light-emitting layer from other layers to recombine and emit light.

[0004] There are many defects in the n-type AlGaN layer, which will lead to an increase in the ionization energy of the Si donor and a decrease in the electron mobility, making Si doping in the n-type AlGaN layer difficult and having low conductivity, resulting in low electron recombination efficiency and easy current congestion in the final ultraviolet light-emitting diode epitaxial wafer, and low luminous efficiency and luminous uniformity of the ultraviolet light-emitting diode epitaxial wafer. Summary of the invention

[0005] The embodiment of the present disclosure provides an ultraviolet light-emitting diode epitaxial wafer with an electron transport layer and a preparation method thereof, which can improve the electron recombination efficiency and the planar expansion of the current to improve the luminous efficiency and luminous uniformity of the obtained ultraviolet light-emitting diode epitaxial wafer. The technical solution is as follows:

[0006] An embodiment of the present disclosure provides an ultraviolet light emitting diode epitaxial wafer with an electron transport layer, wherein the ultraviolet light emitting diode epitaxial wafer with an electron transport layer comprises a substrate and a buffer layer, an n-type AlGaN layer, an electron transport layer, a light emitting layer and a p-type AlGaN layer sequentially stacked on the substrate, wherein the electron transport layer comprises a BN / n-AlGaN / graphene superlattice, and the BN / n-AlGaN / graphene superlattice comprises BN sublayers, n-AlGaN sublayers and graphene sublayers periodically stacked in sequence.

[0007] Optionally, the thickness of the BN sublayer and the thickness of the n-AlGaN sublayer are both equal to the thickness of the graphene sublayer.

[0008] Optionally, the BN sublayer has a thickness of 3-10 nm.

[0009] Optionally, the period number of the BN / n-AlGaN / graphene superlattice is 3-10.

[0010] Optionally, the n-type impurity of the n-AlGaN sublayer is Si element, and the doping concentration of Si element in the n-AlGaN sublayer is 1×10 17 -1×10 18 cm -3 .

[0011] Optionally, the Al component in the n-AlGaN sublayer is in the range of 40-50%.

[0012] Optionally, the BN sublayer is doped with Mg element.

[0013] The embodiment of the present disclosure provides a method for preparing an ultraviolet light emitting diode epitaxial wafer having an electron transport layer, and the method for preparing an ultraviolet light emitting diode epitaxial wafer having an electron transport layer comprises:

[0014] providing a substrate;

[0015] growing a buffer layer on the substrate;

[0016] growing an n-type AlGaN layer on the buffer layer;

[0017] Growing an electron transport layer on the n-type AlGaN layer, the electron transport layer comprising a BN / n-AlGaN / graphene superlattice, the BN / n-AlGaN / graphene superlattice comprising a BN sublayer, an n-AlGaN sublayer and a graphene sublayer that are periodically stacked in sequence;

[0018] growing a light-emitting layer on the electron transport layer;

[0019] A p-type AlGaN layer is grown on the light emitting layer.

[0020] Optionally, the growth temperature of the BN sublayer is 900-1000° C., and the growth pressure of the BN is 150-300 Torr.

[0021] Optionally, the graphene sublayer is grown using a physical vapor deposition device, the deposition temperature of the graphene sublayer is 1000-1200° C., and the deposition pressure of the graphene sublayer is 0.1-1 atm.

[0022] Optionally, the growth temperature of the n-AlGaN sublayer is 1000-1100° C., and the growth pressure of the n-AlGaN sublayer is 75-100 Torr.

[0023] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure include:

[0024] An electron transport layer is added between the light-emitting layer and the n-type AlGaN layer, and the electron transport layer includes a BN / n-AlGaN / graphene superlattice. The addition of a BN sublayer in the BN / n-AlGaN / graphene superlattice can increase a certain barrier height, promote the lateral expansion of electrons so that the current can enter the light-emitting layer more evenly, and improve the overall light uniformity of the ultraviolet light-emitting diode; and the radius of the B atoms in the BN sublayer is small, which can play a role in fixing dislocations and blocking dislocations from extending upward, so as to ensure the quality of the n-AlGaN sublayer and the graphene sublayer grown on the BN sublayer, reduce defects that extend into the light-emitting layer, and reduce the non-radiative recombination of carriers in the light-emitting layer to improve the light-emitting efficiency of the ultraviolet light-emitting diode. The n-AlGaN sublayer on the BN sublayer can provide a certain amount of electrons, increase the concentration of electrons that can enter the light-emitting layer, and also ensure the mobility of electrons. The graphene sublayer can isolate defects from the light-emitting layer, further reduce defects that can enter the light-emitting layer, and improve the light-emitting efficiency of the light-emitting layer. And due to the strong polarization effect and the two-dimensional material properties of the graphene material itself, a two-dimensional electron gas can be formed at the interface between the n-AlGaN sublayer and the graphene sublayer, and the mobility of electrons can be increased to increase the concentration of electrons that recombine in the light-emitting layer. The luminous efficiency and luminous uniformity of the obtained ultraviolet light-emitting diode can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 It is a schematic structural diagram of an ultraviolet light-emitting diode epitaxial wafer with an electron transport layer provided in an embodiment of the present disclosure;

[0027] Figure 2 It is a schematic structural diagram of another ultraviolet light-emitting diode epitaxial wafer with an electron transport layer provided in an embodiment of the present disclosure;

[0028] Figure 3 It is a flow chart of a method for preparing an ultraviolet light-emitting diode epitaxial wafer with an electron transport layer provided in an embodiment of the present disclosure;

[0029] Figure 4 It is a flow chart of another method for preparing an ultraviolet light-emitting diode epitaxial wafer with an electron transport layer provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0031] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The words "first", "second", "third" and similar words used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", "top", "bottom" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0032] Figure 1 is a schematic diagram of the structure of an ultraviolet light-emitting diode epitaxial wafer with an electron transport layer provided in an embodiment of the present disclosure, with reference to Figure 1 It can be seen that the embodiment of the present disclosure provides an ultraviolet light emitting diode epitaxial wafer with an electron transport layer 4, and the ultraviolet light emitting diode epitaxial wafer with an electron transport layer 4 includes a substrate 1 and a buffer layer 2, an n-type AlGaN layer 3, an electron transport layer 4, a light emitting layer 5 and a p-type AlGaN layer 6 stacked in sequence on the substrate 1, the electron transport layer 4 includes a BN / n-AlGaN / graphene superlattice, and the BN / n-AlGaN / graphene superlattice includes a BN sublayer 41, an n-AlGaN sublayer 42 and a graphene sublayer 43 periodically stacked in sequence.

[0033] An electron transport layer 4 is added between the light-emitting layer 5 and the n-type AlGaN layer 3, and the electron transport layer 4 includes a BN / n-AlGaN / graphene superlattice. The addition of the BN sublayer 41 in the BN / n-AlGaN / graphene superlattice can increase a certain barrier height, promote the lateral expansion of electrons so that the current can enter the light-emitting layer 5 more evenly, and improve the overall luminescence uniformity of the ultraviolet light-emitting diode; and the radius of the B atoms in the BN sublayer 41 is small, which can play a role in fixing dislocations and blocking the dislocations from extending upward, so as to ensure the quality of the n-AlGaN sublayer and the graphene sublayer 43 grown on the BN sublayer 41, reduce defects that extend into the light-emitting layer 5, and reduce the non-radiative recombination of carriers in the light-emitting layer 5 to improve the luminous efficiency of the ultraviolet light-emitting diode. The n-AlGaN sublayer 42 on the BN sublayer 41 can provide a certain amount of electrons, increase the concentration of electrons that can enter the light-emitting layer 5, and also ensure the mobility of electrons. The graphene sublayer 43 can isolate defects from the light-emitting layer 5, further reduce defects that may enter the light-emitting layer 5, and improve the luminous efficiency of the light-emitting layer 5. In addition, due to the strong polarization effect and the two-dimensional material properties of the graphene material itself, a two-dimensional electron gas can be formed at the interface between the n-AlGaN sublayer 42 and the graphene sublayer 43, and the mobility of electrons can also be improved to increase the concentration of electrons that are recombined in the light-emitting layer 5. The luminous efficiency and luminous uniformity of the obtained ultraviolet light-emitting diode can be improved.

[0034] Optionally, the thickness of the BN sublayer 41 and the thickness of the n-AlGaN sublayer 42 are both equal to the thickness of the graphene sublayer 43 .

[0035] The thickness of the BN sublayer 41 and the thickness of the n-AlGaN sublayer 42 are both equal to the thickness of the graphene sublayer 43. The thickness of all sublayers in the BN / n-AlGaN / graphene superlattice are equal, which facilitates preparation and can also ensure that there are fewer defects in the light-emitting layer 5 grown on the BN / n-AlGaN / graphene superlattice, and the concentration of electrons entering the light-emitting layer 5 is higher, so that the light-emitting uniformity and light-emitting efficiency of the obtained light-emitting layer 5 are higher.

[0036] In other implementations provided in the present disclosure, the thickness of the BN sublayer 41 and the thickness of the graphene sublayer 43 in the BN / n-AlGaN / graphene superlattice may also be set to different thicknesses, which is not limited in the present disclosure.

[0037] Optionally, the thickness of the BN sublayer 41 is 3-10 nm.

[0038] When the thickness of the BN sublayer 41 is within the above range, the electron and defect blocking effect can be ensured, while the quality of the BN sublayer 41 itself is also good, and the preparation cost of the BN sublayer 41 itself is also low.

[0039] It should be noted that when the thickness of the BN sublayer 41 is within the range of 3-10 nm, the thickness of the n-AlGaN sublayer 42 and the graphene sublayer 43, which are equal to the BN sublayer 41, are also within the range of 3-10 nm. The BN / n-AlGaN / graphene superlattice is easy to prepare as a whole and can ensure that the quality of the obtained light-emitting layer 5 is good.

[0040] In an implementation provided in the present disclosure, the thickness of the BN sublayer 41 , the n-AlGaN sublayer 42 , and the graphene sublayer 43 may also be 5 nm, and the present disclosure does not make any limitation thereto.

[0041] Exemplarily, the period number of the BN / n-AlGaN / graphene superlattice is 3-10.

[0042] When the number of periods of the BN / n-AlGaN / graphene superlattice is within the above range, the BN / n-AlGaN / graphene superlattice can effectively release the stress accumulated in the epitaxial material between the light-emitting layer 5 and the substrate 1 to improve the crystal quality of the light-emitting layer 5 and the BN / n-AlGaN / graphene superlattice, and the overall preparation cost of the ultraviolet light-emitting diode epitaxial wafer will not be too high.

[0043] It should be noted that in the BN / n-AlGaN / graphene superlattice, there is one BN sublayer 41, one n-AlGaN sublayer 42 and one graphene sublayer 43, and a total of three layers form one period. In the BN / n-AlGaN / graphene superlattice, there is one BN sublayer 41, one n-AlGaN sublayer 42 and one graphene sublayer 43, and these three layers are alternately stacked to form the BN / n-AlGaN / graphene superlattice.

[0044] Optionally, the n-type impurity of the n-AlGaN sublayer 42 is Si element, and the doping concentration of Si element in the n-AlGaN sublayer 42 is 1×10 17 -1×10 18 cm -3 .

[0045] The doping concentration of Si element in the n-AlGaN sublayer 42 is within the above range, which can ensure that the obtained n-AlGaN sublayer 42 has good quality. At the same time, the n-AlGaN sublayer 42 can also provide more sufficient electrons, thereby increasing the concentration of electrons that can enter the light-emitting layer 5 to improve the efficiency of carrier recombination luminescence in the light-emitting layer 5.

[0046] Optionally, the Al component in the n-AlGaN sublayer 42 is in the range of 40-50%.

[0047] The value range of the Al component in the n-AlGaN sublayer 42 is within the above range, which can ensure that the quality of the n-AlGaN sublayer 42 is good and can also play a certain role in current expansion, and the doping rate of the Si element in the n-AlGaN sublayer 42 will not be too low.

[0048] Figure 2 is a schematic diagram of the structure of another ultraviolet light-emitting diode epitaxial wafer with an electron transport layer provided in an embodiment of the present disclosure, with reference to Figure 2 It can be seen that the ultraviolet light-emitting diode epitaxial wafer may also include a substrate 1 and a buffer layer 2, an n-type AlGaN layer 3, an electron transport layer 4, a light-emitting layer 5, a p-type AlGaN layer 6 and a p-type GaN layer 7 stacked in sequence on the substrate 1, the electron transport layer 4 includes a BN / n-AlGaN / graphene superlattice, and the BN / n-AlGaN / graphene superlattice includes a BN sublayer 41, an n-AlGaN sublayer 42 and a graphene sublayer 43 periodically stacked in sequence.

[0049] It should be noted that the structure of the electron transport layer 4 can refer to Figure 1 The structure of the electron transport layer 4 is shown in , so it will not be described again here.

[0050] Optionally, the substrate 1 may be a sapphire substrate 1 .

[0051] For example, the buffer layer 2 may include a first AlN sublayer 21 and a second AlN sublayer 22 sequentially stacked on the substrate 1 , and a growth temperature of the first AlN sublayer 21 is lower than a growth temperature of the second AlN sublayer 22 .

[0052] The buffer layer 2 is configured to include a first AlN sublayer 21 and a second AlN sublayer 22 sequentially stacked on the substrate 1. The growth temperature of the first AlN sublayer 21 is lower than the growth temperature of the second AlN sublayer 22, so that a stable transition between the buffer layer 2 and the substrate 1 can be achieved, and the first AlN sublayer 21 grown at a lower temperature can be ensured to grow more densely on the substrate 1, so as to reduce defects in the first AlN sublayer 21. The second AlN sublayer 22 can be grown at a high temperature on the first AlN sublayer 21 and then transition to the growth of the n-type AlGaN sublayer, thereby improving the quality and the preparation efficiency.

[0053] Optionally, the thickness of the first AlN sublayer 21 may be 10-30 nm, and the thickness of the second AlN sublayer 22 may be 2-3 micrometers, which can ensure that the quality of the obtained buffer layer 2 is good.

[0054] It should be noted that in other implementations provided in the present disclosure, the buffer layer 2 may also be configured as a single layer of AlN material or a structure in which gallium nitride or aluminum gallium nitride material is grown on AlN material, and the present disclosure does not impose any limitation on this.

[0055] Exemplarily, the N-type dopant in the n-type AlGaN layer 3 may be Si, and the doping concentration may be 10 18 cm -3 -10 20 cm -3 。

[0056] Optionally, the light-emitting layer 5 includes a plurality of alternately grown quantum barrier layers and quantum well layers. The quantum well layer may be a GaN layer, and the quantum barrier layer may be an AlxGa1-xN (0 < x < 0.3) layer.

[0057] Optionally, the P-type dopant in the p-type AlGaN layer 6 may be Mg, and the doping concentration is 10 17 cm -3 -10 18 cm -3 。

[0058] Exemplarily, the thickness of the p-type GaN layer 7 may be 100 - 300 nm.

[0059] The addition of the p-type GaN layer 7 can be used as a transition layer to achieve good contact with the electrode, and the ohmic contact between the p-type GaN layer 7 and the electrode is also low, which can reduce the resistance between the electrode and the ultraviolet light-emitting diode epitaxial wafer, realize the rapid transfer of current between the electrode and the ultraviolet light-emitting diode epitaxial wafer, reduce the operating voltage required for the obtained ultraviolet light-emitting diode, and improve the service life of the ultraviolet light-emitting diode. When the thickness of the p-type GaN layer 7 is within the above range, it can ensure good quality of the p-type GaN layer 7 itself and also ensure that the p-type GaN layer 7 has sufficient thickness to achieve ohmic contact with the electrode.

[0060] It should be noted that Figure 2 the ultraviolet light-emitting diode in Figure 1 has improved the structure of the buffer layer 2 compared to the ultraviolet light-emitting diode in

[0061] Figure 3 is a flowchart of a method for manufacturing an ultraviolet light-emitting diode epitaxial wafer with an electron transport layer provided by an embodiment of the present disclosure. Referring to Figure 3 it can be seen that the embodiment of the present disclosure provides a method for manufacturing an ultraviolet light-emitting diode epitaxial wafer with an electron transport layer. The method for manufacturing an ultraviolet light-emitting diode epitaxial wafer with an electron transport layer includes:

[0062] S101: Provide a substrate.

[0063] S102: growing a buffer layer on a substrate.

[0064] S103: growing an n-type AlGaN layer on the buffer layer.

[0065] S104: growing an electron transport layer on the n-type AlGaN layer, the electron transport layer comprising a BN / n-AlGaN / graphene superlattice, the BN / n-AlGaN / graphene superlattice comprising a BN sublayer, an n-AlGaN sublayer and a graphene sublayer that are periodically stacked in sequence.

[0066] S105: growing a light-emitting layer on the electron transport layer.

[0067] S106: growing a p-type AlGaN layer on the light-emitting layer.

[0068] An electron transport layer is added between the light-emitting layer and the n-type AlGaN layer, and the electron transport layer includes a BN / n-AlGaN / graphene superlattice. The addition of a BN sublayer in the BN / n-AlGaN / graphene superlattice can increase a certain barrier height, promote the lateral expansion of electrons so that the current can enter the light-emitting layer more evenly, and improve the overall light uniformity of the ultraviolet light-emitting diode; and the radius of the B atoms in the BN sublayer is small, which can play a role in fixing dislocations and blocking dislocations from extending upward, so as to ensure the quality of the n-AlGaN sublayer and the graphene sublayer grown on the BN sublayer, reduce defects that extend into the light-emitting layer, and reduce the non-radiative recombination of carriers in the light-emitting layer to improve the light-emitting efficiency of the ultraviolet light-emitting diode. The n-AlGaN sublayer on the BN sublayer can provide a certain amount of electrons, increase the concentration of electrons that can enter the light-emitting layer, and also ensure the mobility of electrons. The graphene sublayer can isolate defects from the light-emitting layer, further reduce defects that can enter the light-emitting layer, and improve the light-emitting efficiency of the light-emitting layer. And due to the strong polarization effect and the two-dimensional material properties of the graphene material itself, a two-dimensional electron gas can be formed at the interface between the n-AlGaN sublayer and the graphene sublayer, and the mobility of electrons can be increased to increase the concentration of electrons that recombine in the light-emitting layer. The luminous efficiency and luminous uniformity of the obtained ultraviolet light-emitting diode can be improved.

[0069] Optionally, step S104 includes: the growth temperature of the BN sublayer is 900-1000° C., and the growth pressure of BN is 150-300 Torr.

[0070] The growth temperature and growth pressure of the BN sublayer are respectively within the above ranges, which can ensure that the quality of the obtained BN sublayer is good and reduce the defects that may exist inside the electron transport layer.

[0071] For example, during the growth of the BN sublayer, ammonia gas with a flow rate of 20,000-30,000 sccm and a boron source with a flow rate of 20-50 sccm are introduced into the reaction chamber, which can ensure that the quality of the obtained BN sublayer is good and the preparation cost will not be excessively increased.

[0072] Optionally, step S104 includes: the growth temperature of the n-AlGaN sublayer is 1000-1100° C., and the growth pressure of the n-AlGaN sublayer is 75-100 Torr. The quality of the obtained n-AlGaN sublayer can be improved and impurities can be doped into the aluminum gallium nitride material under a low pressure environment, thereby increasing the electron concentration entering the light-emitting layer.

[0073] Exemplarily, step S104 includes: growing the graphene sublayer using a physical vapor deposition device, the deposition temperature of the graphene sublayer is 1000-1200° C., and the deposition pressure of the graphene sublayer is 0.1-1 atm.

[0074] When the deposition temperature and deposition pressure of the graphene sublayer are within the above range, the quality of the obtained graphene sublayer can be improved, so as to improve the crystal quality of the electron transport layer finally obtained. The graphene sublayer is grown using a physical vapor deposition device, which can also improve the density of the graphene sublayer to effectively block defects.

[0075] It should be noted that the structure of the ultraviolet light emitting diode epitaxial wafer obtained after executing step S106 can be referred to Figure 1 The structure of the UV light-emitting diode epitaxial wafer shown in .

[0076] Figure 4 is a flow chart of another method for preparing an ultraviolet light-emitting diode epitaxial wafer with an electron transport layer provided in an embodiment of the present disclosure, with reference to Figure 4 It can be seen that the method for preparing an ultraviolet light-emitting diode epitaxial wafer having an electron transport layer may include:

[0077] S201: providing a substrate.

[0078] Optionally, the substrate may be sapphire (Al2O3) with a (0001) crystal orientation.

[0079] Step S201 may further include: cleaning the substrate. Cleaning can remove impurities on the surface of the substrate to improve the crystal quality of the epitaxial material grown on the substrate.

[0080] S202: growing a buffer layer on the substrate, wherein the buffer layer comprises a first AlN sublayer and a second AlN sublayer sequentially stacked on the substrate.

[0081] For example, the growth temperature of the first AlN sublayer may be 1000-1100°C, and the growth temperature of the second AlN sublayer may be 1300-1400°C.

[0082] The growth temperatures of the first AlN sublayer and the second AlN sublayer are respectively within the above ranges, so that the quality of the first AlN sublayer and the second AlN sublayer can be controlled to be good, and the crystal quality of the buffer layer finally obtained can be effectively improved.

[0083] Optionally, the growth pressure of the first AlN sublayer may be 50-70 mbar, and the growth pressure of the second AlN sublayer may be 40-50 mbar. The crystal quality of the obtained buffer layer can be further improved.

[0084] In an implementation provided by the present disclosure, ammonia and trimethylaluminum can be introduced as reactants during the growth of the first AlN sublayer, the V / III molar ratio is 3000, and the process time is 1000s. Ammonia and trimethylaluminum can be introduced as reactants into the second AlN sublayer, the V / III molar ratio is 300, and the process time is 5000s. The quality of the obtained buffer layer is good, and the present disclosure does not limit this.

[0085] S203: growing an n-type AlGaN layer on the buffer layer.

[0086] Optionally, the thickness of the n-type AlGaN layer is between 0.5 and 2.0 microns, the growth temperature is between 1000° C. and 1200° C., the pressure is between 50 Torr and 200 Torr, and the Si doping concentration is between 10 18 cm -3 -10 20 cm -3 A good quality n-type AlGaN layer can be obtained.

[0087] In other implementations provided by the present disclosure, the thickness of the n-type AlGaN layer is 700 nm, and the growth pressure of the n-type AlGaN layer may be 100 mbar, which is not limited by the present disclosure.

[0088] S204: growing an electron transport layer on the n-type AlGaN layer, the electron transport layer comprising a BN / n-AlGaN / graphene superlattice, the BN / n-AlGaN / graphene superlattice comprising a BN sublayer, an n-AlGaN sublayer and a graphene sublayer that are periodically stacked in sequence.

[0089] Step S204 can refer to Figure 3 The step S104 shown in FIG. 1 is not described in detail here.

[0090] S205: growing a light-emitting layer on the electron transport layer.

[0091] The multi-quantum well layer includes a plurality of alternately grown quantum barrier layers and quantum well layers. The quantum well layer can be a GaN layer, and the quantum barrier layer can be an AlxGa1-xN (0 < x < 0.3) layer. For example, the multi-quantum well layer is composed of 4 to 12 periods of GaN and AlxGa1-xN (0 < x < 0.3). The thickness of the quantum well layer is about 3 nm, the growth temperature ranges from 850 °C to 950 °C, and the pressure ranges between 100 Torr and 300 Torr; the thickness of the quantum barrier layer is between 8 nm and 20 nm, the growth temperature is between 900 °C and 1000 °C, and the growth pressure is between 50 Torr and 200 Torr.

[0092] S206: Grow a p-type AlGaN layer on the light-emitting layer.

[0093] Optionally, grow a p-type AlGaN layer on the electron blocking layer at a growth temperature of 950 - 1050 °C and a growth pressure of 100 Torr - 600 Torr.

[0094] S207: Grow a p-type GaN layer on the p-type AlGaN layer.

[0095] Optionally, the growth temperature of the p-type GaN layer is 800 - 900 °C, which can improve the crystal quality of the obtained p-type GaN layer.

[0096] After performing step S207, the structure of the ultraviolet light-emitting diode epitaxial wafer obtained can refer to Figure 2 the structure of the ultraviolet light-emitting diode epitaxial wafer shown in

[0097] It should be noted that in the embodiments of the present disclosure, the epitaxial material can be mainly prepared by an MOCVD device. Among them, high-purity H2 (hydrogen) or high-purity N2 (nitrogen) or a mixed gas of high-purity H2 and high-purity N2 is used as the carrier gas, high-purity NH3 is used as the N source, trimethylgallium (TMGa) and triethylgallium (TEGa) are used as the gallium sources, silane (SiH4) is used as the N-type dopant, trimethylaluminum (TMAl) is used as the aluminum source, and bis(cyclopentadienyl)magnesium (CP2Mg) is used as the P-type dopant.

[0098] As described above, it is not any form of limitation to the present disclosure. Although the present disclosure has been disclosed as above through embodiments, it is not intended to limit the present disclosure. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content without departing from the technical solution of the present disclosure. However, as long as it does not depart from the technical solution of the present disclosure, any simple modification, equivalent change, and modification made to the above embodiments according to the technical essence of the present disclosure still fall within the scope of the technical solution of the present disclosure.

Claims

1. An ultraviolet light-emitting diode epitaxial wafer having an electron transport layer, characterized in that: The ultraviolet light-emitting diode epitaxial wafer with an electron transport layer includes a substrate and a buffer layer, an n-type AlGaN layer, an electron transport layer, a light-emitting layer and a p-type AlGaN layer stacked in sequence on the substrate, the electron transport layer includes a BN / n-AlGaN / graphene superlattice, and the BN / n-AlGaN / graphene superlattice includes BN sublayers, n-AlGaN sublayers and graphene sublayers stacked in sequence periodically.

2. The ultraviolet light emitting diode epitaxial wafer with an electron transport layer according to claim 1, characterized in that: The thickness of the BN sublayer and the thickness of the n-AlGaN sublayer are both equal to the thickness of the graphene sublayer.

3. The ultraviolet light emitting diode epitaxial wafer with an electron transport layer according to claim 2, characterized in that: The thickness of the BN sublayer is 3-10 nm.

4. The ultraviolet light emitting diode epitaxial wafer with an electron transport layer according to any one of claims 1 to 3, characterized in that: The period number of the BN / n-AlGaN / graphene superlattice is 3-10.

5. The ultraviolet light emitting diode epitaxial wafer with an electron transport layer according to any one of claims 1 to 3, characterized in that: The n-type impurity of the n-AlGaN sublayer is Si element, and the doping concentration of Si element in the n-AlGaN sublayer is 1×10 17 -1×10 20 cm -3 .

6. The ultraviolet light emitting diode epitaxial wafer with an electron transport layer according to any one of claims 1 to 3, characterized in that: The Al component in the n-AlGaN sublayer ranges from 40% to 50%.

7. A method for preparing an ultraviolet light-emitting diode epitaxial wafer having an electron transport layer, characterized in that: The method for preparing the ultraviolet light-emitting diode epitaxial wafer with an electron transport layer comprises: providing a substrate; growing a buffer layer on the substrate; growing an n-type AlGaN layer on the buffer layer; Growing an electron transport layer on the n-type AlGaN layer, the electron transport layer comprising a BN / n-AlGaN / graphene superlattice, the BN / n-AlGaN / graphene superlattice comprising a BN sublayer, an n-AlGaN sublayer and a graphene sublayer that are periodically stacked in sequence; growing a light-emitting layer on the electron transport layer; A p-type AlGaN layer is grown on the light emitting layer.

8. The method for preparing an ultraviolet light emitting diode epitaxial wafer with an electron transport layer according to claim 7, characterized in that: The growth temperature of the BN sublayer is 900-1000° C., and the growth pressure of the BN is 150-300 Torr.

9. The method for preparing an ultraviolet light emitting diode epitaxial wafer with an electron transport layer according to claim 7, characterized in that: The graphene sublayer is grown by using a physical vapor deposition device, the deposition temperature of the graphene sublayer is 1000-1200° C., and the deposition pressure of the graphene sublayer is 0.1-1 atm.

10. The method for preparing an ultraviolet light emitting diode epitaxial wafer with an electron transport layer according to claim 7, characterized in that: The growth temperature of the n-AlGaN sublayer is 1000-1100° C., and the growth pressure of the n-AlGaN sublayer is 75-100 Torr.

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