CN108550675A - A kind of LED epitaxial slice and preparation method thereof - Google Patents

Abstract

The invention discloses a light-emitting diode epitaxial wafer and a preparation method thereof, belonging to the technical field of semiconductors. The epitaxial wafer includes a substrate and a buffer layer, an N-type semiconductor layer, an active layer, an electron blocking layer, and a P-type semiconductor layer stacked on the substrate in sequence. The buffer layer and the electron blocking layer include multiple composite structures stacked in sequence, each A composite structure includes a first sublayer and a second sublayer stacked in sequence, the material of the first sublayer is aluminum boron nitride, and the material of the second sublayer is indium gallium nitride. The aluminum boron nitride of the present invention increases the energy level of the electron blocking layer, raises the energy level of the conduction band, reduces the energy level of the valence band, increases the forbidden band width between the conduction band and the valence band, and enhances the blocking effect on electrons At the same time, the injection of holes is increased, so that under the condition of effectively blocking the transition of electrons to the P-type semiconductor layer, it is beneficial to inject holes into the active layer, increase the number of holes injected into the active layer, and improve the luminous efficiency of the LED.

Description

A light-emitting diode epitaxial wafer and its preparation method

technical field

The invention relates to the technical field of semiconductors, in particular to a light-emitting diode epitaxial wafer.

Background technique

A light-emitting diode (English: Light Emitting Diode, referred to as: LED) is a semiconductor electronic component that can emit light. LED has the advantages of energy saving and environmental protection, high reliability, long service life, etc., so it is currently receiving more and more attention and research.

Epitaxial wafers are the primary products in the LED manufacturing process. Existing LED epitaxial wafers include substrate, buffer layer, N-type semiconductor layer, active layer, electron blocking layer and P-type semiconductor layer, buffer layer, N-type semiconductor layer, active layer, electron blocking layer and P-type semiconductor layer Layers are stacked sequentially on the substrate. The substrate is used to provide a growth surface for epitaxial materials, the buffer layer is used to alleviate the lattice mismatch between the substrate and the N-type semiconductor layer, the N-type semiconductor layer is used to provide electrons for recombination and light emission, and the P-type semiconductor layer is used for Holes for recombination luminescence are provided, the active layer is used for recombination luminescence of electrons and holes, and the electron blocking layer is used for blocking electrons from transitioning to the P-type semiconductor layer for non-radiative recombination with holes.

In the process of realizing the present invention, the inventor finds that there are at least the following problems in the prior art:

The electron blocking layer is usually implemented with aluminum gallium nitride (AlGaN) with a thickness greater than 50nm. If the thickness of the electron blocking layer is too small, it may not be able to effectively block the transition of electrons to the P-type semiconductor layer, resulting in non-radiative recombination in the P-type semiconductor layer. If the thickness of the electron blocking layer is too large, although it can effectively block the transition of electrons to the P-type semiconductor layer, it may also limit the hole injection of the P-type semiconductor layer into the active layer and electrons to perform radiative recombination and light emission.

Contents of the invention

The embodiment of the present invention provides a light-emitting diode epitaxial wafer and a preparation method thereof, which can solve the problem of being unable to effectively block the transition of electrons to the P-type semiconductor layer or limit the hole injection of the P-type semiconductor layer into the active layer and electrons to perform radiative recombination and light emission. . Described technical scheme is as follows:

On the one hand, an embodiment of the present invention provides a light-emitting diode epitaxial wafer, the light-emitting diode epitaxial wafer includes a substrate, a buffer layer, an N-type semiconductor layer, an active layer, an electron blocking layer, and a P-type semiconductor layer, and the buffer layer, the N-type semiconductor layer, the active layer, the electron blocking layer and the P-type semiconductor layer are sequentially stacked on the substrate, and the electron blocking layer includes a plurality of composite structures stacked in sequence, Each of the composite structures includes a first sublayer and a second sublayer stacked in sequence, the first sublayer is made of aluminum boron nitride, and the second sublayer is made of indium gallium nitride.

Optionally, the electron blocking layer has a thickness of 10 nm˜15 nm.

Optionally, the number of the composite structures is 2-4.

Optionally, each of the composite structures further includes a third sublayer, the third sublayer is arranged between the first sublayer and the second sublayer, and the material of the third sublayer adopts Aluminum Gallium Nitride.

Preferably, the material of the third sublayer is _{AlyGa1 -yN} , 0.2≤y≤0.4.

Optionally, the material of the first sublayer is B _x Al _1-x N, 0.1≤x≤0.2.

Optionally, the material of the second sublayer is In _z Ga _1-z N, 0.02≤z≤0.2.

On the other hand, an embodiment of the present invention provides a method for preparing a light-emitting diode epitaxial wafer, the preparation method comprising:

providing a substrate;

sequentially growing a buffer layer, an N-type semiconductor layer, an active layer, an electron blocking layer, and a P-type semiconductor layer on the substrate;

Wherein, the electron blocking layer includes a plurality of composite structures stacked in sequence, each of the composite structures includes a first sublayer and a second sublayer stacked in sequence, and the material of the first sublayer is aluminum boron nitride, The material of the second sublayer is InGaN.

Optionally, the growth temperature of the electron blocking layer is 900°C-1200°C.

Optionally, the growth pressure of the electron blocking layer is 100 torr-300 torr.

The beneficial effects brought by the technical solution provided by the embodiments of the present invention are:

By designing the electron blocking layer as multiple composite structures stacked in sequence, each composite structure includes a first sublayer and a second sublayer, and the material of the first sublayer is aluminum boron nitride. Compared with aluminum gallium nitride, Aluminum boron nitride can increase the energy level of the electron blocking layer, increase the energy level of the conduction band, reduce the energy level of the valence band, increase the forbidden band width between the conduction band and the valence band, and enhance the blocking effect on electrons. At the same time, the injection of holes is increased, so that under the condition of effectively blocking the transition of electrons to the P-type semiconductor layer, it is beneficial to inject holes into the active layer, increase the number of holes injected into the active layer, and improve the luminous efficiency of the LED. Moreover, the material of the second sub-layer is InGaN, which can accumulate holes, which is beneficial for hole injection into the active layer, further increases the number of holes injected into the active layer, and improves the luminous efficiency of the LED. In addition, the first sublayer and the second sublayer are laminated alternately to form a superlattice structure, which can relieve the stress between the first sublayer and the second sublayer due to heterogeneous materials.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

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

Fig. 2 is a schematic structural view of an electron blocking layer provided by an embodiment of the present invention;

Fig. 3 is a schematic structural diagram of another electron blocking layer provided by an embodiment of the present invention;

Fig. 4 is a flow chart of a method for manufacturing a light-emitting diode epitaxial wafer provided by an embodiment of the present invention.

Detailed ways

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

An embodiment of the present invention provides a light-emitting diode epitaxial wafer. FIG. 1 is a schematic structural diagram of a light-emitting diode epitaxial wafer provided by an embodiment of the present invention. Referring to FIG. 1, the light-emitting diode epitaxial wafer includes a substrate 1, a buffer layer 2, an N-type The semiconductor layer 3, the active layer 4, the electron blocking layer 5 and the P-type semiconductor layer 6, the buffer layer 2, the N-type semiconductor layer 3, the active layer 4, the electron blocking layer 5 and the P-type semiconductor layer 6 are sequentially stacked on the substrate 1 on.

FIG. 2 is a schematic structural diagram of an electron blocking layer provided by an embodiment of the present invention. Referring to FIG. 2, in this embodiment, the electron blocking layer 6 includes a plurality of composite structures 60 stacked in sequence, and each composite structure 60 includes a first sublayer 61 and a second sublayer 62 stacked in sequence, and the first sublayer The material of 61 is boron aluminum nitride (BAlN), and the material of the second sublayer 62 is indium gallium nitride (InGaN).

In the embodiment of the present invention, the electron blocking layer is designed as a plurality of composite structures stacked in sequence, each composite structure includes a first sublayer and a second sublayer, the material of the first sublayer is aluminum boron nitride, and aluminum nitride Compared with gallium, aluminum boron nitride can increase the energy level of the electron blocking layer, increase the energy level of the conduction band, reduce the energy level of the valence band, increase the forbidden band width between the conduction band and the valence band, and enhance the electron The blocking effect, while increasing the injection of holes, so that in the case of effectively blocking the transition of electrons to the P-type semiconductor layer, it is beneficial to inject holes into the active layer, increase the number of holes injected into the active layer, and improve the luminous efficiency of the LED . Moreover, the material of the second sub-layer is InGaN, which can accumulate holes, which is beneficial for hole injection into the active layer, further increases the number of holes injected into the active layer, and improves the luminous efficiency of the LED. In addition, the first sublayer and the second sublayer are laminated alternately to form a superlattice structure, which can relieve the stress between the first sublayer and the second sublayer due to heterogeneous materials.

In a specific implementation, the electron blocking layer may be doped with a P-type dopant, such as magnesium (Mg), or may not be doped with a P-type dopant. Specifically, when the electron blocking layer is doped with a P-type dopant, the doping concentration of the P-type dopant in the electron blocking layer may be 3*10 ¹⁷ /cm ³ -8*10 ¹⁷ /cm ³ .

Optionally, the thickness of the electron blocking layer 6 may be 10 nm˜15 nm, preferably 12 nm or 15 nm.

In order to effectively prevent electrons from transitioning into the P-type semiconductor layer and holes for non-radiative luminescence, the thickness of the electron blocking layer is usually greater than 50nm, resulting in too large a thickness of the electron blocking layer. On the one hand, it will affect the light emitted by the active layer from the inside of the LED. On the other hand, it will increase the series resistance in the LED, causing the forward voltage of the LED to increase. The embodiment of the present invention utilizes the strong blocking effect of aluminum boron nitride on electrons to reduce the thickness of the electron blocking layer to 10nm to 15nm, which can effectively avoid adverse effects on the light extraction efficiency and forward conduction voltage of the LED, and improve the performance of the LED. The light extraction efficiency reduces the forward conduction voltage of the LED.

If the thickness of the electron blocking layer is less than 10nm, the electronic blocking layer may not be able to effectively block the transition of electrons into the P-type semiconductor layer due to the thickness of the electron blocking layer, which will cause LED overflow and affect the reliability and service life of the LED; if the electron blocking layer If the thickness of the electron blocking layer is greater than 15nm, it may not be able to further effectively improve the blocking effect on electrons and the injection efficiency of holes, resulting in waste of materials. If the thickness of the electron blocking layer is greater than 50nm, it may also affect the light extraction efficiency and forward conduction voltage of the LED.

Optionally, the number of composite structures 60 may be 2 to 4, preferably 3.

If the number of composite structures is less than 2, the superlattice structure cannot be formed, resulting in greater stress in the electron blocking layer, which in turn affects the crystal quality of the epitaxial wafer and reduces the luminous efficiency of the LED. It may also be due to the fact that the number of composite structures is too small However, it cannot effectively block the transition of electrons into the P-type semiconductor layer, causing LED overflow; if the number of composite structures is greater than 4, the thickness of the electron blocking layer may increase due to the large number of composite structures, which will affect the The active layer emits light from the LED, and on the other hand, it also increases the series resistance in the LED, resulting in an increase in the forward conduction voltage of the LED.

Optionally, the material of the first sublayer 61 can be B _x Al _1-x N, 0.1≤x≤0.2, preferably x=0.14.

If x<0.1, it may be that the molar content of the boron component in the first sublayer is too low to effectively block electrons from transitioning into the P-type semiconductor layer, causing LED overflow, affecting the reliability and service life of the LED, and possibly In order to effectively avoid preventing electrons from jumping into the P-type semiconductor layer for non-radiative recombination with holes, the thickness of the electron blocking layer is increased, resulting in too large thickness of the electron blocking layer, which affects the light extraction efficiency and forward conduction voltage of the LED; if x >0.2, it may be that the internal stress of the electron blocking layer is too high due to too high molar content of the boron component in the first sub-layer, which affects the crystal quality of the epitaxial wafer and reduces the luminous efficiency of the LED on the contrary.

Optionally, the material of the second sublayer 62 may be In _z Ga _1-z N, 0.02≤z≤0.2, preferably z=0.1.

If z<0.02, the molar content of the indium component in the second sublayer may be too low to play a role in accumulation, thereby failing to achieve the effect of increasing the number of holes injected into the active layer; if z>0.2, then It may be that the crystal quality of the electron blocking layer is poor because the molar content of the indium component in the second sublayer is too high, which further affects the crystal quality of the epitaxial wafer as a whole, resulting in a decrease in the luminous efficiency of the LED.

In the above implementation manner, that is, when the composite structure 60 is composed of the first sublayer 61 and the second sublayer 62 as shown in FIG. 2 , the thickness of the first sublayer 61 can be 2 nm to 3 nm, preferably 2 nm; The thickness of the sublayer 62 may be 2nm˜5nm, preferably 2nm.

If the thickness of the first sub-layer is less than 2nm, it may be that the first sub-layer is too thin to effectively block the transition of electrons into the P-type semiconductor layer, resulting in LED overflow, which affects the reliability and service life of the LED. Avoid blocking the transition of electrons to the P-type semiconductor layer for non-radiative recombination with holes to increase the molar content of the boron component in the first sublayer, resulting in too high a molar content of the boron component, which in turn causes too much internal stress in the electron blocking layer. If the thickness of the first sublayer is greater than 3nm, it may cause the thickness of the electron blocking layer to be too large due to the thickness of the first sublayer, which will affect the LED's luminous efficiency. Light extraction efficiency and forward voltage.

If the thickness of the second sublayer is less than 2nm, it may not be able to accumulate because the second sublayer is too thin to achieve the effect of increasing the number of holes injected into the active layer; if the thickness of the second sublayer is greater than 5nm, the thickness of the electron blocking layer may be too large because the third sublayer is too thick, which will affect the light extraction efficiency and forward conduction voltage of the LED. At the same time, the crystal quality of the electron blocking layer may be poor, which will affect the overall epitaxial wafer The quality of the crystal will reduce the luminous efficiency of the LED.

FIG. 3 is a schematic structural diagram of another electron blocking layer provided by an embodiment of the present invention. Referring to FIG. 3 , optionally, each composite structure 60 may include a third sublayer 63 in addition to the first sublayer 61 and the second sublayer 62, and the third sublayer 63 is arranged on the first sublayer 61. Between the second sublayer 62 and the third sublayer 63 is made of AlGaN.

There is a large lattice mismatch between the first sublayer formed with aluminum boron nitride and the second sublayer formed with indium gallium nitride, resulting in poor crystal quality of the electron blocking layer, which in turn causes the overall epitaxial wafer The quality of the crystal is poor, which affects the luminous efficiency of the LED. In the embodiment of the present invention, the third sublayer formed by aluminum gallium nitride is inserted between the first sublayer and the second sublayer, which can effectively alleviate the lattice mismatch between the first sublayer and the second sublayer, and improve the electron density. The crystal quality of the barrier layer can avoid adverse effects on the luminous efficiency of the LED. Moreover, AlGaN has a higher energy level, which can also strengthen the blocking effect on electrons, and further prevent electrons from transitioning into the P-type semiconductor layer to perform non-radiative recombination with holes.

Preferably, the material of the third sublayer 63 may be _{AlyGa1 -yN} , 0.2≤y≤0.4, preferably y=0.3.

If y<0.2, the lattice mismatch between the first sublayer formed by aluminum boron nitride may be caused due to the low molar content of the aluminum component in the third sublayer, which affects the crystal quality of the electron blocking layer, Finally, the luminous efficiency of the LED is low; if y>0.4, the molar content of the gallium component in the third sublayer may be too low to cause a lattice mismatch with the second sublayer formed by using InGaN , will also affect the crystal quality of the electron blocking layer, and finally cause the luminous efficiency of the LED to be low.

In the above implementation manner, that is, when the composite structure 60 is composed of the first sublayer 61, the third sublayer 63 and the second sublayer 62 as shown in FIG. It is preferably 2 nm; the thickness of the third sublayer 63 is 1 nm˜3.5 nm, preferably 1 nm; the thickness of the second sublayer 62 is 2 nm˜4.5 nm, preferably 2 nm.

If the thickness of the third sublayer is less than 1 nm, it may be that the third sublayer is too thin to effectively alleviate the lattice mismatch between the first sublayer and the second sublayer, resulting in poor crystal quality of the electron blocking layer, Finally, the luminous efficiency of the LED is low; if the thickness of the third sublayer is greater than 3.5nm, the overall thickness of the electron blocking layer may be too large due to the thickness of the third sublayer, which will affect the light extraction efficiency and forward conduction voltage of the LED. .

In addition, as when the composite structure 60 is composed of the first sublayer 61 and the second sublayer 62 as shown in FIG. Prevent electrons from transitioning into the P-type semiconductor layer, causing LED overflow, affecting the reliability and service life of the LED, and may also increase the first The molar content of the boron component in the sublayer causes the molar content of the boron component to be too high, which in turn causes too much internal stress in the electron blocking layer, affects the crystal quality of the epitaxial wafer, and reduces the luminous efficiency of the LED instead; if the first sublayer If the thickness is greater than 3nm, the thickness of the electron blocking layer may be too large because the first sub-layer is too thick, thereby affecting the light extraction efficiency and forward conduction voltage of the LED.

If the thickness of the second sublayer is less than 2nm, it may not be able to accumulate because the second sublayer is too thin to achieve the effect of increasing the number of holes injected into the active layer; if the thickness of the second sublayer is greater than 4.5nm, the overall thickness of the electron blocking layer may be too large because the third sub-layer is too thick, thereby affecting the light extraction efficiency and forward conduction voltage of the LED.

Specifically, the material of the substrate 1 can be sapphire, preferably sapphire with [0001] crystal orientation. The material of the buffer layer 2 can be aluminum nitride or gallium nitride. The material of the N-type semiconductor layer 3 can be N-type doped (such as silicon) gallium nitride. The active layer 4 can include multiple quantum wells and multiple quantum barriers, and multiple quantum wells and multiple quantum barriers are alternately stacked; the material of the quantum wells can be indium gallium nitride, such as In _t Ga _1-t N,0 <t<1; gallium nitride can be used as the material of the quantum barrier. The material of the P-type semiconductor layer 6 can be P-type doped (such as magnesium) gallium nitride.

Further, the thickness of the buffer layer 2 may be 15nm-35nm, preferably 25nm. The thickness of the N-type semiconductor layer 3 can be 1 μm to 5 μm, preferably 3 μm; the doping concentration of the N-type dopant in the N-type semiconductor layer 3 can be 10 ¹⁸ cm ^-3 to 10 ¹⁹ cm ^-3 , preferably 5* 10 ¹⁸ cm ^-3 . The thickness of quantum well can be 2.5nm～3.5nm, is preferably 3nm; The thickness of quantum barrier can be 9nm～20nm, is preferably 15nm; The quantity of quantum well is identical with the quantity of quantum barrier, and the quantity of quantum barrier can be 5～ 11, preferably 8. The thickness of the P-type semiconductor layer 6 may be 100nm-800nm, preferably 450nm; the doping concentration of the P-type dopant in the P-type semiconductor layer 6 may be 3*10 ¹⁷ /cm ³ -8*10 ¹⁷ /cm ³ .

Optionally, as shown in FIG. 1, the light-emitting diode epitaxial wafer may further include an undoped gallium nitride layer 7, and the undoped gallium nitride layer 7 is arranged between the buffer layer 2 and the N-type semiconductor layer 3, so as to Further alleviate the lattice mismatch between the substrate and the N-type semiconductor layer, improve the overall crystal quality of the epitaxial wafer, and then improve the luminous efficiency of the LED.

Further, the thickness of the undoped gallium nitride layer 7 may be 1 μm˜5 μm, preferably 3 μm.

Optionally, as shown in FIG. 1, the light emitting diode epitaxial wafer may also include a P-type contact layer 8, which is disposed on the P-type semiconductor layer 6, so as to realize the electrodes or electrodes formed during the fabrication process of the epitaxial wafer and the chip. Ohmic contact between transparent conductive films.

Specifically, the material of the P-type contact layer 8 can be P-type doped InGaN.

Further, the thickness of the P-type contact layer 8 may be 5 nm to 300 nm, preferably 150 nm; the doping concentration of the P-type dopant in the P-type contact layer 8 may be 3*10 ¹⁷ /cm ³ to 8*10 ¹⁷ /cm 3 cm ³ .

An embodiment of the present invention provides a method for preparing a light emitting diode epitaxial wafer, which is suitable for preparing the light emitting diode epitaxial wafer shown in FIG. 1 . Fig. 4 is a flowchart of a method for preparing a light-emitting diode epitaxial wafer provided by an embodiment of the present invention. Referring to Fig. 4, the preparation method includes:

Step 201: Provide a substrate.

Optionally, this step 201 may include:

Controlling the temperature to 1000°C to 1200°C (preferably 1100°C), annealing the substrate in a hydrogen atmosphere for 6 minutes to 10 minutes (preferably 8 minutes);

The substrate is nitrided.

Cleaning the surface of the substrate through the above steps prevents impurities from being mixed into the epitaxial wafer, which is beneficial to improving the growth quality of the epitaxial wafer.

Step 202: growing a buffer layer, an N-type semiconductor layer, an active layer, an electron blocking layer and a P-type semiconductor layer sequentially on the substrate.

In this embodiment, the electron blocking layer includes a plurality of composite structures stacked in sequence, and each composite structure includes a first sublayer and a second sublayer stacked in sequence, the material of the first sublayer is aluminum boron nitride, and the second sublayer is made of aluminum boron nitride. The material of the sublayer is InGaN.

Optionally, the growth temperature of the electron blocking layer may be 900°C-1200°C.

If the growth temperature of the electron blocking layer is lower than 900°C, the crystal quality of the electron blocking layer may be poor due to the low growth temperature of the electron blocking layer, which will affect the overall crystal quality of the epitaxial wafer, resulting in a decrease in the luminous efficiency of the LED; If the growth temperature of the electron blocking layer is higher than 1200°C, the precipitation of indium may be caused by the high growth temperature of the electron blocking layer, and the molar content of the indium component in the second sublayer is too low to play the role of accumulation, thus The effect of increasing the number of holes injected into the active layer cannot be achieved, or the thickness of the electron blocking layer is increased in order to ensure a certain content of indium in the electron blocking layer, resulting in the thickness of the electron blocking layer being too large, which in turn affects the light output of the LED efficiency and forward voltage.

Further, the growth temperature of the electron blocking layer may be 1090°C to 1200°C, preferably 1150°C.

Optionally, the growth pressure of the electron blocking layer may be 100 torr to 300 torr.

If the growth pressure of the electron blocking layer is lower than 100torr, it may affect the growth rate of the electron blocking layer due to the too low growth pressure of the electron blocking layer, thereby affecting the overall production efficiency of the epitaxial wafer; if the growth pressure of the electron blocking layer is higher than 300torr , it may affect the growth quality of the electron blocking layer because the growth pressure of the electron blocking layer is too high, and then affect the overall crystal quality of the epitaxial wafer, resulting in a decrease in the luminous efficiency of the LED.

Further, the growth pressure of the electron blocking layer may be 100 torr to 190 torr, preferably 150 torr.

Specifically, this step 202 may include:

In the first step, the temperature is controlled at 400°C to 600°C (preferably 500°C), the pressure is 400torr to 600torr (preferably 500torr), and a buffer layer is grown on the substrate;

In the second step, the temperature is controlled at 1000°C to 1200°C (preferably 1100°C), the pressure is 100torr to 500torr (preferably 300torr), and an N-type semiconductor layer is grown on the buffer layer;

The third step is to grow an active layer on the N-type semiconductor layer; wherein, the growth temperature of the quantum well is 720°C to 829°C (preferably 770°C), and the pressure is 100torr to 500torr (preferably 300torr); the growth of the quantum barrier The temperature is 850°C to 959°C (preferably 900°C), and the pressure is 100torr to 500torr (preferably 300torr);

The fourth step is to grow an electron blocking layer on the active layer;

In the fifth step, control the temperature to 850°C-1080°C (preferably 930°C), and the pressure to 100torr-300torr (preferably 200torr), and grow a P-type semiconductor layer on the electron blocking layer.

Optionally, after the first step, the preparation method may also include:

The control temperature is 1000°C-1200°C (preferably 1100°C), the pressure is 400torr-600torr (preferably 500torr), and the buffer layer is annealed in situ for 5-10 minutes (preferably 8 minutes).

Optionally, before the second step, the preparation method may also include:

The temperature is controlled to be 1000°C-1100°C (preferably 1050°C), the pressure is 100torr-500torr (preferably 300torr), and an undoped gallium nitride layer is grown on the buffer layer.

Accordingly, an N-type semiconductor layer is grown on the undoped GaN layer.

Optionally, after the sixth step, the preparation method may also include:

Control the temperature to 850°C-1050°C (preferably 950°C), and the pressure to 100torr-300torr (preferably 200torr), and grow a P-type contact layer on the P-type semiconductor layer.

It should be noted that after the above-mentioned epitaxial growth is completed, the temperature will be lowered to 650° C. to 850° C. (preferably 750° C.), and the epitaxial wafer is grown in a nitrogen atmosphere for 5 minutes to 15 minutes (preferably 10 minutes). Annealing treatment, and then reduce the temperature of the epitaxial wafer to room temperature.

The obtained epitaxial wafer is subjected to chip manufacturing processes such as cleaning, deposition, photolithography, and etching to form a single LED chip with a size of 9mil*7mil. The LED chip was tested under a working current of 20mA, and it was found that the LED chip made of the epitaxial wafer obtained in the embodiment of the present invention, compared with the LED chip made of the epitaxial wafer obtained in the prior art, the luminous brightness increased by 1%- 1.5%.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. A light-emitting diode epitaxial wafer, said light-emitting diode epitaxial wafer comprising a substrate, a buffer layer, an N-type semiconductor layer, an active layer, an electron blocking layer and a P-type semiconductor layer, said buffer layer, said N-type semiconductor layer layer, the active layer, the electron blocking layer and the P-type semiconductor layer are sequentially stacked on the substrate, and it is characterized in that the electron blocking layer includes a plurality of composite structures stacked in sequence, and each of the The composite structure includes a first sublayer and a second sublayer stacked in sequence, the first sublayer is made of aluminum boron nitride, and the second sublayer is made of indium gallium nitride. 2 . The light emitting diode epitaxial wafer according to claim 1 , wherein the electron blocking layer has a thickness of 10 nm˜15 nm. 3 . 3. The light-emitting diode epitaxial wafer according to claim 1 or 2, characterized in that, the number of the composite structures is 2-4. 4. The light-emitting diode epitaxial wafer according to claim 1 or 2, wherein each of the composite structures further comprises a third sublayer, and the third sublayer is arranged between the first sublayer and the Between the second sublayers, the material of the third sublayer is aluminum gallium nitride. 5. The light emitting diode epitaxial wafer according to claim 4, characterized in that, the material of the third sublayer is _{AlyGa1 -} yN, 0.2≤y≤0.4. 6. The light-emitting diode epitaxial wafer according to claim 1 or 2, wherein the material of the first sub-layer is B _x Al _1-x N, 0.1≤x≤0.2. 7. The light-emitting diode epitaxial wafer according to claim 1 or 2, characterized in that, the material of the second sub-layer is In _z Ga _1-z N, 0.02≤z≤0.2. 8. A method for preparing a light-emitting diode epitaxial wafer, characterized in that the method for preparing comprises: providing a substrate; sequentially growing a buffer layer, an N-type semiconductor layer, an active layer, an electron blocking layer, and a P-type semiconductor layer on the substrate; Wherein, the electron blocking layer includes a plurality of composite structures stacked in sequence, each of the composite structures includes a first sublayer and a second sublayer stacked in sequence, and the material of the first sublayer is aluminum boron nitride, The material of the second sublayer is InGaN. 9. The preparation method according to claim 8, characterized in that, the growth temperature of the electron blocking layer is 900°C-1200°C. 10. The preparation method according to claim 8 or 9, characterized in that the growth pressure of the electron blocking layer is 100 torr-300 torr.