CN115714155A - Deep ultraviolet light emitting diode epitaxial wafer, preparation method thereof and deep ultraviolet light emitting diode - Google Patents

Abstract

The invention discloses a deep ultraviolet light emitting diode epitaxial wafer and a preparation method thereof, and a deep ultraviolet light emitting diode, wherein the deep ultraviolet light emitting diode epitaxial wafer comprises a substrate, and a buffer layer, a nucleation layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electronic barrier layer, a P-type AlGaN layer and a P-type contact layer which are sequentially stacked on the substrate; the nucleation layer comprises a two-dimensional AlGaN nucleation preparation layer, an Al nano-dot layer, an AlGaN nano-cluster nucleation point layer and an AlGaN nucleation layer which are sequentially stacked on the buffer layer. The deep ultraviolet light emitting diode epitaxial wafer provided by the invention can reduce the dislocation density of the deep ultraviolet light emitting diode, reduce the non-radiative recombination efficiency of a quantum well and improve the light emitting efficiency of the deep ultraviolet light emitting diode.

Description

Deep ultraviolet light emitting diode epitaxial wafer and preparation method thereof, deep ultraviolet light emitting diode

technical field

The invention relates to the field of optoelectronic technology, in particular to a deep ultraviolet light emitting diode epitaxial wafer, a preparation method thereof, and a deep ultraviolet light emitting diode.

Background technique

Deep ultraviolet solid light sources are widely used in sterilization, water purification, biochemistry and medicine, high-density optical storage light sources, fluorescence analysis systems and related information sensing fields.

The efficiency of the ultraviolet LED reported in the early stage is extremely low. When the luminous wavelength is 400nm, the external quantum efficiency is 50%. As the wavelength is further shortened, the external quantum efficiency drops sharply, and it is only 0.2% at 250nm. This is mainly due to the large difference in the atomic mobility and adhesion coefficient between Al atoms and Ga atoms in the growth of GaN and AlGaN materials, the mobility of Al atoms is lower than that of Ga atoms, and the adhesion coefficient is also higher, so that During the growth process of AlGaN materials with high Al composition, a large number of three-dimensional island structures are formed, which makes it difficult to move freely on the surface and grow into a smooth two-dimensional plane, which will directly and greatly reduce the crystal quality of AlGaN. The defect density in AlGaN material is relatively high, which can reach the dislocation density of 10 ¹⁰ cm ^-2 -10 ¹¹ cm ^-2 , while the dislocation density in GaN is relatively low at 10 ⁸ cm ^-2 , such a high dislocation density The density will turn this region into a non-radiative recombination center, reducing the radiative recombination efficiency in the active region and thus affecting the optoelectronic performance of nitride semiconductor devices.

Contents of the invention

The technical problem to be solved by the present invention is to provide a deep ultraviolet light emitting diode epitaxial wafer, which reduces the dislocation density of deep ultraviolet light emitting diodes, reduces the non-radiative recombination efficiency of quantum wells, and improves the luminous efficiency of deep ultraviolet light emitting diodes.

The technical problem to be solved by the present invention is also to provide a method for preparing a deep ultraviolet light-emitting diode epitaxial wafer, which has a simple process and can stably produce the above-mentioned deep ultraviolet light-emitting diode epitaxial wafer with good performance.

In order to solve the above technical problems, the present invention provides a deep ultraviolet light-emitting diode epitaxial wafer, including a substrate and a buffer layer, a nucleation layer, a non-doped AlGaN layer, an N-type AlGaN layer, Multi-quantum well layer, electron blocking layer, P-type AlGaN layer and P-type contact layer;

The nucleation layer includes a two-dimensional AlGaN nucleation preparation layer, an Al nano-dot layer, an AlGa nano-cluster nucleation point layer and an AlGaN nucleation layer stacked in sequence on the buffer layer.

In one embodiment, the thickness of the two-dimensional AlGaN nucleation preparation layer is 10nm-100nm;

The thickness of the Al nano-dot layer is 5nm-50nm;

The thickness of the AlGa nanocluster nucleation point layer is 50nm-500nm;

The thickness of the AlGaN nucleation layer is 0.5 μm-5 μm.

In one embodiment, the Al component concentration in the two-dimensional AlGaN nucleation preparation layer is 0.1-1.

In one embodiment, the Al component concentration in the AlGaN nucleation layer is 0.1-1.

In order to solve the above problems, the invention provides a method for preparing a deep ultraviolet light-emitting diode epitaxial wafer, comprising the following steps:

Prepare the substrate;

sequentially depositing a buffer layer, a nucleation layer, a non-doped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electron blocking layer, a P-type AlGaN layer and a P-type contact layer on the substrate;

The nucleation layer includes a two-dimensional AlGaN nucleation preparation layer, an Al nano-dot layer, an AlGa nano-cluster nucleation point layer and an AlGaN nucleation layer stacked in sequence on the buffer layer.

In one embodiment, depositing the two-dimensional AlGaN nucleation preparation layer on the buffer layer comprises the following steps:

The temperature of the reaction chamber is controlled at 700°C-1000°C, the pressure is controlled at 50torr-300torr, N ₂ and NH ₃ are fed as carrier gas, and N source, Ga source and Al source are fed to complete the deposition.

In one embodiment, depositing the Al nano-dot layer on the two-dimensional AlGaN nucleation preparation layer comprises the following steps:

Firstly, the temperature of the reaction chamber is controlled at 900°C-1100°C, the pressure is controlled at 100torr-500torr, N ₂ is fed as carrier gas, and Al source is fed to complete the deposition.

In one embodiment, depositing the AlGa nanocluster nucleation dot layer on the Al nano dot layer comprises the following steps:

The temperature of the reaction chamber is controlled at 900°C-1100°C, the pressure is controlled at 100torr-500torr, N ₂ is fed as carrier gas, and Al source and Ga source are fed to complete the deposition.

In one embodiment, depositing the AlGaN nucleation layer on the AlGa nanocluster nucleation point layer comprises the following steps:

Control the temperature of the reaction chamber at 1000°C-1200°C, control the pressure at 50torr-300torr, feed _N2 as carrier gas, _N2 , _NH3 and _H2 as carrier gas, Ga source, Al source and N The source completes the deposition.

Correspondingly, the present invention also provides a deep ultraviolet light emitting diode, which comprises the above-mentioned deep ultraviolet light emitting diode epitaxial wafer.

Implement the present invention, have following beneficial effect:

In the present invention, a nucleation layer is grown on the buffer layer, and the nucleation layer includes a two-dimensional AlGaN nucleation preparation layer, an Al nano-dot layer, an AlGa nano-cluster nucleation point layer and an AlGaN layer stacked sequentially on the buffer layer. nucleation layer. Among them, the two-dimensional AlGaN nucleation preparation layer provides a flat nucleation surface for the growth of the Al nano-dot layer, reducing the contact angle of its nucleation growth; the Al nano-dot layer controls the density of the nucleation point, and the Al nano-dot layer The nucleation point density is closely related to the density of the subsequent layered structure; the AlGa nanocluster nucleation point layer introduces Ga atoms, so that the Al nano point layer continues to grow, and at the same time reduces the lattice mismatch with the subsequent AlGaN nucleation layer , improve the crystal quality of the AlGaN nucleation layer; the density of the AlGaN nucleation layer is closely related to the dislocation density of the deep ultraviolet epitaxial layer, and the fusion of the AlGaN nucleation layer produces line defects, which reduces the crystal quality of the GaN epitaxial layer. The two-dimensional AlGaN nucleation preparation layer, Al nano-dot layer, and AlGa nano-cluster nucleation point layer can effectively control the density of the AlGaN nucleation layer to control the dislocation density, reduce the defect density, reduce the non-radiative recombination efficiency of quantum wells, and improve Luminous efficiency of deep ultraviolet light-emitting diodes.

Description of drawings

FIG. 1 is a schematic structural view of a deep ultraviolet light-emitting diode epitaxial wafer provided by the present invention.

Among them: substrate 1, buffer layer 2, nucleation layer 3, non-doped AlGaN layer 4, N-type AlGaN layer 5, multiple quantum well layer 6, electron blocking layer 7, P-type AlGaN layer 8, P-type contact layer 9 , a two-dimensional AlGaN nucleation preparation layer 31 , an Al nano-dot layer 32 , an AlGa nano-cluster nucleation point layer 33 , and an AlGaN nucleation layer 34 .

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below.

Unless otherwise stated or contradictory, terms and phrases used herein have the following meanings:

In the present invention, "its combination", "any combination thereof", "any combination thereof" and the like include all suitable combinations of any two or more of the listed items.

In the present invention, "preferred" is only to describe an implementation or an example with better effects, and it should be understood that it does not constitute a limitation to the protection scope of the present invention.

In the present invention, the technical features described in open form include closed technical solutions consisting of the enumerated features, as well as open technical solutions including the enumerated features.

In the present invention, when referring to a numerical interval, unless otherwise specified, both endpoints of the numerical interval are included.

The traditional nucleation layer is a large number of three-dimensional island structures, and the high nucleation density leads to the formation of a large number of dislocations when the nucleation layer islands merge and extend along the direction of the epitaxial layer to the quantum well to form a non-radiative recombination center, reducing the deep ultraviolet light-emitting diode. internal quantum efficiency.

In order to solve the above problems, the present invention provides a deep ultraviolet light-emitting diode epitaxial wafer, as shown in Figure 1, comprising a substrate 1 and a buffer layer 2, a nucleation layer 3, a non-doped A mixed AlGaN layer 4, an N-type AlGaN layer 5, a multi-quantum well layer 6, an electron blocking layer 7, a P-type AlGaN layer 8 and a P-type contact layer 9;

The nucleation layer 3 includes a two-dimensional AlGaN nucleation preparation layer 31 , an Al nano-dot layer 32 , an AlGa nano-cluster nucleation point layer 33 and an AlGaN nucleation layer 34 sequentially stacked on the buffer layer 2 .

In one embodiment, the thickness of the two-dimensional AlGaN nucleation preparation layer is 10nm-100nm; the thickness of the Al nano-dot layer is 5nm-50nm; the thickness of the AlGa nano-cluster nucleation point layer is 50nm -500 nm; the thickness of the AlGaN nucleation layer is 0.5 μm-5 μm. In one embodiment, the Al component concentration in the two-dimensional AlGaN nucleation preparation layer is 0.1-1; the Al component concentration in the AlGaN nucleation layer is 0.1-1.

In the nucleation layer of the present invention, the two-dimensional AlGaN nucleation preparation layer provides a smooth nucleation surface for the growth of the Al nano-dot layer, reducing the contact angle of its nucleation growth; the Al nano-dot layer controls The density of the nucleation point, and the density of the nucleation point of the Al nano-dot layer is closely related to the density of the AlGaN nucleation layer; the AlGa nano-cluster nucleation point layer introduces Ga atoms, so that the Al nano-dot layer continues to grow up, At the same time, the lattice mismatch with the subsequent AlGaN nucleation layer is reduced, and the crystal quality of the AlGaN nucleation layer is improved; the density of the AlGaN nucleation layer is closely related to the dislocation density of the deep ultraviolet epitaxial layer, and the fusion of the AlGaN nucleation layer produces line defects , reduce the crystal quality of the GaN epitaxial layer, and the density of the AlGaN nucleation layer can be effectively controlled to control the dislocation density by depositing a two-dimensional AlGaN nucleation preparation layer, Al nano-dot layer, and AlGa nano-cluster nucleation point layer before, reducing Defect density reduces the non-radiative recombination efficiency of quantum wells and improves the luminous efficiency of deep ultraviolet light-emitting diodes.

Except above-mentioned nucleation layer, the characteristics of other layered structures of the present invention are as follows:

In one embodiment, the substrate is selected from one of a sapphire substrate, a SiO ₂ sapphire composite substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, and a zinc oxide substrate. Preferably, the substrate is a sapphire substrate. Sapphire is currently the most commonly used substrate material. The sapphire substrate has a mature preparation process, low price, easy cleaning and handling, and good stability at high temperatures.

In one embodiment, the buffer layer is an AlN buffer layer. The use of the AlN buffer layer provides the nucleation center with the same orientation as the substrate, releasing the stress caused by the lattice mismatch between AlGaN and the substrate and the thermal stress caused by the thermal expansion coefficient mismatch, and further growth provides a flat surface. Nucleation surface, reducing the contact angle of its nucleation growth, so that the island-shaped GaN grains can be connected into a surface within a small thickness, transforming into two-dimensional epitaxial growth, improving the crystal quality of the subsequent deposited AlGaN layer and reducing the dislocation density , improve the multiple quantum well layer radiation recombination efficiency. In one embodiment, the thickness of the buffer layer is 80nm-150nm.

In one embodiment, the growth temperature of the non-doped AlGaN layer is 1000° C.-1300° C., the growth pressure is 50 torr-500 torr, and the growth thickness is 1 μm-5 μm. Preferably, the growth temperature of the non-doped AlGaN layer is 1200° C., the growth pressure is 100 torr, and the growth thickness is 2 μm-3 μm. The non-doped AlGaN layer has higher growth temperature and lower pressure, and the prepared GaN crystal quality is better. At the same time, as the thickness of AlGaN increases, the compressive stress will be released through stacking faults, line defects will be reduced, and the crystal quality will be improved. increase, the reverse leakage is reduced, but increasing the thickness of the AlGaN layer consumes a lot of MO source metal-organic source materials, which greatly increases the epitaxial cost of light-emitting diodes. Therefore, the thickness is controlled at 2μm-3μm, which not only saves production costs, but also GaN materials have Higher crystal quality.

In one embodiment, the growth temperature of the N-type AlGaN layer is 1000°C-1300°C, the Si doping concentration is 1*10 ¹⁹ atoms/cm ³ -5*10 ²⁰ atoms/cm ³ , and the thickness is 1 μm- 5 μm. Preferably, the growth temperature is 1200° C., the growth pressure is 100 torr, the growth thickness is 2 μm-3 μm, and the Si doping concentration is 2.5*10 ¹⁹ atoms/cm ³ . First, the N-type doped AlGaN layer provides sufficient electron and hole recombination for the ultraviolet LED to emit light. Secondly, the resistivity of the N-type doped AlGaN layer is higher than that of the transparent electrode on the P-type GaN layer, so sufficient Si doping can effectively reduce the resistivity of the N-type GaN layer. Finally, the sufficient thickness of the N-type doped AlGaN layer can effectively release the stress and improve the luminous efficiency of the light-emitting diode.

In one embodiment, the multiple quantum well layers are alternately stacked _{AlxGa1 -xN} quantum well layers and _{AlyGa1 -yN} quantum barrier layers, and the number of stacking periods is 3-15. Among them, the growth temperature of Al _x Ga _1-x N quantum well layer is 950°C-1150°C, the thickness is 2nm-5nm, the growth pressure is 50torr-300torr, and the Al composition is 0.2-0.6; the Al _y Ga _1-y N quantum barrier layer The growth temperature is 1000°C-1300°C, the thickness is 5nm-15nm, the growth pressure is 50torr-300torr, and the Al component is 0.4-0.8.

Preferably, the number of stacking cycles is 9, wherein the growth temperature of the Al _x Ga _1-x N quantum well layer is 1050°C, the thickness is 3.5nm, the pressure is 200torr, and the Al composition is 0.55; the Al _y Ga _1-y N quantum barrier The layer growth temperature was 1150° C., the thickness was 11 nm, the growth pressure was 200 torr, and the Al composition was 0.7. Multiple quantum wells are regions where electrons and holes recombine. Reasonable structural design can significantly increase the degree of overlap between electron and hole wave functions, thereby improving the luminous efficiency of LED devices.

In one embodiment, the electron blocking layer is an AlGaN electron blocking layer with a thickness of 10nm-100nm, a growth temperature of 1000°C-1100°C, a pressure of 100torr-300torr, and an Al component of 0.4-0.8. Preferably, the thickness of the AlGaN electron blocking layer is 30nm, the Al composition is 0.75, the growth temperature is 1050°C, and the growth pressure is 200torr, which can not only effectively limit the electron overflow, but also reduce the blocking of holes, and improve the hole vector to the quantum well. Injection efficiency, reduce carrier Auger recombination, improve luminous efficiency of light-emitting diodes.

In one embodiment, the growth temperature of the P-type AlGaN layer is 1000°C-1100°C, the thickness is 20nm-200nm, the growth pressure is 100torr-600torr, and the Mg doping concentration is 1*10 ¹⁹ atoms/cm ³ -5 *10 ²⁰ atoms/cm ³ .

Preferably, the growth temperature of the P-type AlGaN layer is 1050° C., the thickness is 100 nm, the growth pressure is 200 torr, and the Mg doping concentration is 5*10 ¹⁹ atoms/cm ³ . If the Mg doping concentration is too high, the crystal quality will be damaged, while doping A lower impurity concentration will affect the hole concentration. At the same time, the P-type doped AlGaN layer can effectively fill up the epitaxial layer to obtain a deep ultraviolet LED epitaxial wafer with a smooth surface.

In one embodiment, the growth temperature of the P-type contact layer is 900°C-1100°C, the thickness is 5nm-50nm, the growth pressure is 100torr-600torr, and the Mg doping concentration is 5*10 ¹⁹ atoms/cm ³ - 5*10 ²⁰ atoms/cm ³ .

Preferably, the growth temperature of the P-type doped AlGaN layer is 950° C., the thickness is 10 nm, the growth pressure is 200 torr, the Mg doping concentration is 1*10 ²⁰ atoms/cm ³ , and the P-type contact layer with high doping concentration reduces contact resistance.

Correspondingly, the present invention also provides a method for preparing the above-mentioned deep ultraviolet light-emitting diode epitaxial wafer, comprising the following steps:

S1. Prepare the substrate;

S2, sequentially depositing a buffer layer, a nucleation layer, a non-doped AlGaN layer, an N-type AlGaN layer, a multiple quantum well layer, an electron blocking layer, a P-type AlGaN layer, and a P-type contact layer on the substrate;

The nucleation layer includes a two-dimensional AlGaN nucleation preparation layer, an Al nano-dot layer, an AlGa nano-cluster nucleation point layer and an AlGaN nucleation layer stacked in sequence on the buffer layer.

In one embodiment, the step S2 includes the following steps:

S21. Depositing an AlN buffer layer on the front surface of the substrate by PVD.

S22. Depositing the two-dimensional AlGaN nucleation preparation layer on the buffer layer:

The temperature of the reaction chamber is controlled at 700°C-1000°C, the pressure is controlled at 50torr-300torr, N ₂ and NH ₃ are fed as carrier gas, and N source, Ga source and Al source are fed to complete the deposition.

S23. Depositing the Al nano-dot layer on the two-dimensional AlGaN nucleation preparation layer:

Firstly, the temperature of the reaction chamber is controlled at 900°C-1100°C, the pressure is controlled at 100torr-500torr, N ₂ is fed as carrier gas, and Al source is fed to complete the deposition.

It should be noted that, in one embodiment, the substrate used in the present invention is a PSS substrate, the deposition direction of which is mainly the C surface, and the other surfaces of the PSS image are basically not deposited; Al thin film layer is not formed on the bottom, but Al nano dots are obtained.

S24. Depositing the AlGa nanocluster nucleation dot layer on the Al nano dot layer:

The temperature of the reaction chamber is controlled at 900°C-1100°C, the pressure is controlled at 100torr-500torr, N ₂ is fed as carrier gas, and Al source and Ga source are fed to complete the deposition.

It should be noted that as the Al nano-dot layer continues to deposit the AlGa nano-cluster layer, the AlGa nano-cluster layer continues to grow with the Al nano-dot layer as a similar crystal nucleus, and the AlGa nano-cluster layer continues to grow according to the epitaxial growth conditions, such as high pressure. The nanocluster layer tends to grow three-dimensionally, so the subsequent deposition is the nucleation point of the AlGa nanocluster.

S25. Depositing the AlGaN nucleation layer on the AlGa nanocluster nucleation point layer:

Control the temperature of the reaction chamber at 1000°C-1200°C, control the pressure at 50torr-300torr, feed _N2 as carrier gas, _N2 , _NH3 and _H2 as carrier gas, Ga source, Al source and N The source completes the deposition.

S26. Depositing the non-doped AlGaN layer on the AlGaN nucleation layer:

The temperature of the reaction chamber is controlled to be 1000°C-1300°C, the growth pressure is 50torr-500torr, and the N source, Ga source and Al source are supplied to complete the deposition.

S27. Depositing the N-type AlGaN layer on the non-doped AlGaN layer:

The temperature of the reaction chamber is controlled at 1000°C-1300°C, the pressure is 50torr-300torr, and Si source, Al source, N source and Ga source are fed to complete the deposition.

S28. Depositing the multiple quantum well layer on the N-type AlGaN layer:

First control the temperature of the reaction chamber at 950°C-1150°C, the pressure at 50torr-300torr, feed in N source, Ga source and Al source to complete the Al _x Ga _1-x N quantum well layer deposition, and then control the temperature at 1000°C -1300°C, continue to feed N source, Ga source and Al source to complete _{AlyGa 1-y} N deposition, and repeat stacking for 3-15 cycles.

S29. Depositing the electron blocking layer on the multiple quantum well layer:

The temperature of the reaction chamber is controlled at 1000°C-1100°C, the pressure is 100torr-300torr, and N source, Ga source and Al source are fed to complete the AlGaN layer deposition.

S30, depositing the P-type AlGaN layer and the P-type contact layer on the electron blocking layer:

The temperature of the reaction chamber is controlled at 1000°C-1100°C, the pressure is 100torr-600torr, and Mg source, N source, Ga source and Al source are introduced to complete the deposition of the P-type AlGaN layer, and then the temperature of the reaction chamber is controlled at 900°C-1100°C. The pressure is 100torr-600torr, and the Mg source, N source, Ga source and Al source are fed to complete the deposition of the P-type AlGaN contact layer.

Correspondingly, the present invention also provides a deep ultraviolet light emitting diode, which comprises the above-mentioned deep ultraviolet light emitting diode epitaxial wafer.

Above, MOCVD equipment, CVD equipment or PVD equipment are used to complete the deposition process, and the present invention does not limit the deposition method. High-purity N ₂ (nitrogen) and H ₂ (hydrogen) were used as carrier gases. High-purity NH ₃ (ammonia) provides N (nitrogen) source, what the aluminum source selects is TMAl (trimethylaluminum), what the magnesium source selects is Cp ₂ Mg (magnesocene), respectively adopts TMGa (trimethylgallium ) and TEGa (triethylgallium) as the gallium source, and silane (SiH ₄ ) as the N-type dopant, not limited to the above list.

Further illustrate the present invention with specific embodiment below:

Example 1

This embodiment provides a deep ultraviolet light-emitting diode epitaxial wafer, including a substrate and a buffer layer, a nucleation layer, a non-doped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, and an electronic layer sequentially stacked on the substrate. barrier layer, P-type AlGaN layer and P-type contact layer;

The nucleation layer includes a two-dimensional AlGaN nucleation preparation layer, an Al nano-dot layer, an AlGa nano-cluster nucleation point layer and an AlGaN nucleation layer stacked in sequence on the buffer layer.

The thickness of the two-dimensional AlGaN nucleation preparation layer is 50 nm, the thickness of the Al nano-dot layer is 20 nm, the thickness of the AlGa nano-cluster nucleation point layer is 350 nm, and the thickness of the AlGaN nucleation layer is 1.9 μm.

The Al component concentration in the two-dimensional AlGaN nucleation preparation layer is 0.5, and the Al component concentration in the AlGaN nucleation layer is 0.45.

The preparation method of the above-mentioned deep ultraviolet light-emitting diode epitaxial wafer comprises the following steps:

S1. Prepare the substrate;

S2, sequentially depositing a buffer layer, a nucleation layer, a non-doped AlGaN layer, an N-type AlGaN layer, a multiple quantum well layer, an electron blocking layer, a P-type AlGaN layer, and a P-type contact layer on the substrate;

Described step S2 comprises the following steps:

S21. Depositing an AlN buffer layer on the front surface of the substrate by PVD.

S22. Depositing the two-dimensional AlGaN nucleation preparation layer on the buffer layer:

The temperature of the reaction chamber is controlled at 820°C, the pressure is controlled at 100torr, N ₂ and NH ₃ are fed as carrier gas, and N, Ga and Al sources are fed to complete the deposition.

S23. Depositing the Al nano-dot layer on the two-dimensional AlGaN nucleation preparation layer:

Firstly, the temperature of the reaction chamber is controlled at 980°C, the pressure is controlled at 300torr, N ₂ is fed as carrier gas, and Al source is fed to complete the deposition.

S24. Depositing the AlGa nanocluster nucleation dot layer on the Al nano dot layer:

The temperature of the reaction chamber is controlled at 980°C, the pressure is controlled at 300torr, N ₂ is fed as a carrier gas, and Al and Ga sources are fed to complete the deposition.

S25. Depositing the AlGaN nucleation layer on the AlGa nanocluster nucleation point layer:

The temperature of the reaction chamber is controlled at 1050°C, the pressure is controlled at 150torr, N ₂ is fed as carrier gas, N ₂ , NH ₃ and H ₂ are fed as carrier gas, and Ga source, Al source and N source are fed to complete the deposition.

S26. Depositing the non-doped AlGaN layer on the AlGaN nucleation layer:

The temperature of the reaction chamber is controlled at 1200° C., the growth pressure is 100 torr, N source, Ga source and Al source are supplied to complete the deposition and control the thickness to 2.5 μm.

S27. Depositing the N-type AlGaN layer on the non-doped AlGaN layer:

The temperature of the reaction chamber is controlled at 1200° C., the pressure is 100 torr, and Si source, Al source, N source and Ga source are introduced to complete the deposition and control the thickness to 2.5 μm.

S28. Depositing the multiple quantum well layer on the N-type AlGaN layer:

First control the temperature of the reaction chamber at 1150°C, the pressure at 200torr, and feed in N source, Ga source and Al source to complete the Al _x Ga _1-x N quantum well layer deposition and control the thickness to 3.5nm, and the Al composition to 0.55; Then control the temperature at 1150°C and the growth pressure at 200torr, continue to feed N source, Ga source and Al source to complete the deposition of _{AlyGa 1-y} N and control the thickness to 11nm, and the Al composition to 0.7; repeat stacking for 9 cycles .

S29. Depositing the electron blocking layer on the multiple quantum well layer:

The temperature of the reaction chamber is controlled at 1050° C., the pressure is 200 torr, N source, Ga source and Al source are fed to complete the AlGaN layer deposition and the thickness is controlled to be 30 nm, and the Al composition is 0.75.

S30, depositing the P-type AlGaN layer and the P-type contact layer on the electron blocking layer:

The temperature of the reaction chamber is controlled at 1050°C, the pressure is 200torr, and the Mg source, N source, Ga source and Al source are fed to complete the deposition of the P-type AlGaN layer and the thickness is controlled to 100nm, and the Mg doping concentration is 5*10 ¹⁹ atoms/cm ³ ; Then control the temperature of the reaction chamber at 950°C and the pressure of 200torr, and feed in Mg source, N source, Ga source and Al source to complete the deposition of the P-type AlGaN contact layer and control the thickness to 10nm, and the Mg doping concentration to 1*10 ²⁰ atoms /cm ³ .

Example 2

The difference between this embodiment and Embodiment 1 lies in that: the thickness of the two-dimensional AlGaN nucleation preparation layer is 10 nm, and refer to Embodiment 1 for the rest.

Example 3

The difference between this embodiment and Embodiment 1 lies in that the thickness of the two-dimensional AlGaN nucleation preparation layer is 100 nm, and the rest refer to Embodiment 1.

Example 4

The difference between this example and Example 1 lies in that the thickness of the Al nano-dot layer is 5nm, and refer to Example 1 for the rest.

Example 5

The difference between this example and Example 1 lies in that: the thickness of the Al nano-dot layer is 50nm, and refer to Example 1 for the rest.

Example 6

The difference between this example and Example 1 lies in that the thickness of the AlGa nanocluster nucleation point layer is 50 nm, and refer to Example 1 for the rest.

Example 7

The difference between this embodiment and embodiment 1 lies in that the thickness of the AlGa nanocluster nucleation point layer is 500 nm, and the rest refer to embodiment 1.

Example 8

The difference between this embodiment and embodiment 1 lies in that the Al component concentration in the two-dimensional AlGaN nucleation preparation layer is 0.1, and the Al component concentration in the AlGaN nucleation layer is 0.1. All the others refer to Example 1.

Example 9

The difference between this embodiment and embodiment 1 lies in that the Al component concentration in the two-dimensional AlGaN nucleation preparation layer is 0.65, and the Al component concentration in the AlGaN nucleation layer is 0.55. All the others refer to Example 1.

Comparative example 1

This comparative example provides a deep ultraviolet light-emitting diode epitaxial wafer, which is different from Example 1 in that: the nucleation layer is only an AlGaN nucleation layer with a thickness of 1.9 μm. All the other are identical with embodiment 1.

The epitaxial wafers of deep ultraviolet light-emitting diodes prepared in Example 1-Example 9 and Comparative Example 1 were prepared into 15mil*15mil chips using the same chip process conditions. 300 LED chips were extracted respectively. Tested at a current of 120mA/60mA, and calculated the improvement rate of light efficiency of each embodiment relative to Comparative Example 1. The specific test results are shown in Table 1.

Table 1 shows the performance test results of deep ultraviolet light-emitting diode epitaxial wafers prepared in embodiment 1-embodiment 9

From the above results, it can be known that the present invention grows a nucleation layer on the buffer layer, and the nucleation layer includes a two-dimensional AlGaN nucleation preparation layer, an Al nano-dot layer, and an AlGa nano-cluster formation layer sequentially stacked on the buffer layer. Nucleation point layer and AlGaN nucleation layer. Among them, the two-dimensional AlGaN nucleation preparation layer provides a flat nucleation surface for the growth of the Al nano-dot layer, reducing the contact angle of its nucleation growth; the Al nano-dot layer controls the density of the nucleation point, and the Al nano-dot layer The nucleation point density is closely related to the density of the subsequent layered structure; the AlGa nanocluster nucleation point layer introduces Ga atoms, so that the Al nano point layer continues to grow, and at the same time reduces the lattice mismatch with the subsequent AlGaN nucleation layer , improve the crystal quality of the AlGaN nucleation layer; the density of the AlGaN nucleation layer is closely related to the dislocation density of the deep ultraviolet epitaxial layer, and the fusion of the AlGaN nucleation layer produces line defects, which reduces the crystal quality of the GaN epitaxial layer. The two-dimensional AlGaN nucleation preparation layer, Al nano-dot layer, and AlGa nano-cluster nucleation point layer can effectively control the density of the AlGaN nucleation layer to control the dislocation density, reduce the defect density, reduce the non-radiative recombination efficiency of quantum wells, and improve Luminous efficiency of deep ultraviolet light-emitting diodes.

The above is the preferred embodiment of the invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also considered as protection scope of the present invention.

Claims (10)

1. The deep ultraviolet light emitting diode epitaxial wafer is characterized by comprising a substrate, and a buffer layer, a nucleating layer, an undoped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electronic barrier layer, a P-type AlGaN layer and a P-type contact layer which are sequentially stacked on the substrate;

the nucleating layer comprises a two-dimensional AlGaN nucleating preparation layer, an Al nano-dot layer, an AlGaN nano-cluster nucleating point layer and an AlGaN nucleating layer which are sequentially stacked on the buffer layer.

2. The deep ultraviolet light emitting diode epitaxial wafer of claim 1, wherein the thickness of the two-dimensional AlGaN nucleation preparation layer is 10nm to 100nm;

the thickness of the Al nanodot layer is 5nm-50nm;

the thickness of the AlGa nanocluster nucleation point layer is 50-500 nm;

the thickness of the AlGaN nucleating layer is 0.5-5 μm.

3. The deep ultraviolet light emitting diode epitaxial wafer as claimed in claim 1, wherein the concentration of the Al component in the two-dimensional AlGaN nucleation preparation layer is 0.1 to 1.

4. The deep ultraviolet light emitting diode epitaxial wafer of claim 1, wherein the concentration of the Al component in the AlGaN nucleation layer is 0.1 to 1.

5. A preparation method of the deep ultraviolet light-emitting diode epitaxial wafer as claimed in any one of claims 1 to 4, characterized by comprising the following steps:

preparing a substrate;

sequentially depositing a buffer layer, a nucleating layer, a non-doped AlGaN layer, an N-type AlGaN layer, a multi-quantum well layer, an electronic barrier layer, a P-type AlGaN layer and a P-type contact layer on the substrate;

the nucleation layer comprises a two-dimensional AlGaN nucleation preparation layer, an Al nano-dot layer, an AlGaN nano-cluster nucleation point layer and an AlGaN nucleation layer which are sequentially stacked on the buffer layer.

6. The method for preparing the deep ultraviolet light-emitting diode epitaxial wafer as claimed in claim 5, wherein the step of depositing the two-dimensional AlGaN nucleation preparation layer on the buffer layer comprises the following steps:

controlling the temperature of the reaction chamber to 700-1000 ℃, controlling the pressure to 50-300 torr, and introducing N ₂ And NH ₃ And (3) as a carrier gas, and introducing an N source, a Ga source and an Al source to finish deposition.

7. The method for preparing the deep ultraviolet light emitting diode epitaxial wafer as claimed in claim 5, wherein the depositing the Al nanodot layer on the two-dimensional AlGaN nucleation preparation layer comprises the steps of:

firstly, the temperature of the reaction chamber is controlled between 900 ℃ and 1100 ℃, the pressure is controlled between 100torr and 500torr, and N is introduced ₂ As carrier gas, and Al source is introduced to complete deposition.

8. The method of claim 5 wherein depositing the AlGa nanocluster nucleation point layer on the Al nanodot layer comprises the steps of:

controlling the temperature of the reaction chamber at 900-1100 deg.C, controlling the pressure at 100-500 torr, and introducing N ₂ And (3) serving as a carrier gas, and introducing an Al source and a Ga source to finish deposition.

9. The method of claim 5 wherein depositing the AlGaN nucleation layer on the AlGaN nanocluster nucleation site layer comprises the steps of:

controlling the temperature of the reaction chamber to be 1000-1200 ℃, controlling the pressure to be 50-300 torr, and introducing N ₂ As carrier gas, introducing N ₂ 、NH ₃ And H ₂ As carrier gas, throughAnd completing deposition by using a Ga source, an Al source and an N source.

10. A deep ultraviolet light emitting diode, characterized in that the deep ultraviolet light emitting diode comprises the deep ultraviolet light emitting diode epitaxial wafer of any one of claims 1 to 4.

Images