CN109119514B - A kind of preparation method of light-emitting diode epitaxial wafer and light-emitting diode epitaxial wafer - Google Patents

Abstract

The invention discloses a preparation method of a light-emitting diode epitaxial wafer and a light-emitting diode epitaxial wafer, belonging to the technical field of semiconductors. The preparation method includes: using chemical vapor deposition technology to sequentially grow a buffer layer, an N-type semiconductor layer, an active layer, a P-type semiconductor layer and a contact layer on a substrate, and the contact layer is a P-type doped nitride; The surface of the contact layer is irradiated with electrons to increase nitrogen vacancies in the contact layer. By irradiating the surface of the contact layer with electrons, the invention changes the microstructure of the crystal of the contact layer, affects the form and quantity of defects in the contact layer, generates more nitrogen vacancies without changing the ratio of nitrogen elements, and increases the contact layer. The nitrogen vacancies in the P-type dopant promote the incorporation of P-type dopants, improve the effectiveness of the incorporation of doping elements, change the high impurity state caused by heavy doping, improve the mobility of carriers, and improve the electrode and contact layer. The electrical contact reduces the series resistance and improves the light efficiency of the entire LED.

Description

A kind of preparation method of light-emitting diode epitaxial wafer and light-emitting diode epitaxial wafer

technical field

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

Background technique

Light Emitting Diode (English: Light Emitting Diode, LED for short) is a semiconductor electronic component that can emit light. LEDs have attracted widespread attention due to their advantages of energy saving, environmental protection, high reliability, and long service life. For civil lighting, light efficiency and service life are the main criteria, so increasing the luminous efficiency of LEDs and improving the antistatic ability of LEDs are particularly critical for the wide application of LEDs.

Epitaxial wafers are the primary finished products in the LED fabrication process. The existing LED epitaxial wafer includes a substrate, a buffer layer, an N-type semiconductor layer, an active layer and a P-type semiconductor layer, and the buffer layer, the N-type semiconductor layer, the active layer and the P-type semiconductor layer are sequentially stacked on the substrate. The P-type semiconductor layer is used to provide holes for recombination emission, the N-type semiconductor layer is used to provide electrons for recombination emission, the active layer is used for radiative recombination emission of electrons and holes, and the substrate is used to provide epitaxial materials Growth surface; The material of the substrate is usually sapphire, and the material of the N-type semiconductor layer is usually gallium nitride. Sapphire and gallium nitride are heterogeneous materials, and there is a large lattice mismatch between the two. It is used to alleviate the lattice mismatch between the substrate and the N-type semiconductor layer. In addition, in order to form a good ohmic contact with the electrodes in the chip process, a heavily doped contact layer is usually provided on the P-type semiconductor layer.

In the process of realizing the present invention, the inventor found that the prior art has at least the following problems:

The stress and defects caused by the lattice mismatch between sapphire and gallium nitride will extend to the contact layer with epitaxial growth, and the contact layer is heavily doped, so the defect concentration in the contact layer is very high, and the high concentration of defects The migration of carriers will be bound, resulting in low luminous efficiency of LED.

SUMMARY OF THE INVENTION

The embodiments of the present invention provide a preparation method of a light-emitting diode epitaxial wafer and a light-emitting diode epitaxial wafer, which can solve the problem that high-concentration defects in the contact layer in the prior art will constrain the migration of carriers and cause low luminous efficiency of LEDs. question. The technical solution is as follows:

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

A buffer layer, an N-type semiconductor layer, an active layer, a P-type semiconductor layer and a contact layer are sequentially grown on the substrate by chemical vapor deposition technology, and the contact layer is a P-type doped nitride;

The surface of the contact layer is irradiated with electrons to increase nitrogen vacancies in the contact layer.

Optionally, the radiation dose of electron irradiation is 10 ¹⁶ /cm ² to 10 ²² /cm ² .

Optionally, performing electron irradiation on the surface of the contact layer to increase nitrogen vacancies in the contact includes:

The surface of the contact layer is irradiated with an electron beam provided by a transmission electron microscope as a light source.

Preferably, the diameter of the electron beam is 8 μm˜30 μm.

Optionally, the preparation method also includes:

After the electron irradiation of the surface of the contact layer, the contact layer is annealed.

Preferably, the temperature of the annealing treatment is 700°C to 900°C.

Preferably, the contact layer is in a nitrogen atmosphere during the annealing process.

More preferably, the vacuum degree of the nitrogen atmosphere is 10 ^-8 Torr to 10 ^-6 Torr.

Preferably, the duration of the annealing treatment is 15min-50min.

On the other 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, a P-type semiconductor layer, and a contact layer, and the buffer layer layer, the N-type semiconductor layer, the active layer, the P-type semiconductor layer and the contact layer are sequentially stacked on the substrate, and the surface of the contact layer is a surface treated by electron irradiation.

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

By irradiating the surface of the contact layer with electrons, the microstructure of the crystal of the contact layer is changed, the shape and quantity of defects in the contact layer are affected, and more nitrogen vacancies are generated without changing the proportion of nitrogen elements, increasing the amount of nitrogen in the contact layer. Nitrogen vacancies, promote the incorporation of P-type dopants, improve the effectiveness of the incorporation of doping elements, change the high impurity state due to heavy doping, improve the mobility of carriers, and improve the electrical contact between the electrode and the contact layer , reduce the series resistance and improve the light efficiency of the entire LED.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

1 is a flowchart of a method for preparing a light-emitting diode epitaxial wafer provided by an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a light emitting diode epitaxial wafer provided by an embodiment of the present invention.

Detailed ways

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

An embodiment of the present invention provides a method for preparing a light-emitting diode epitaxial wafer. FIG. 1 is a flowchart of a method for preparing a light-emitting diode epitaxial wafer according to an embodiment of the present invention. Referring to FIG. 1 , the preparation method includes:

Step 101: A buffer layer, an N-type semiconductor layer, an active layer, a P-type semiconductor layer and a contact layer are sequentially grown on the substrate by chemical vapor deposition technology, and the contact layer is a P-type doped nitride.

Specifically, this step 101 may include:

The temperature is controlled to be 400°C to 600°C (preferably 500°C), the pressure is 400torr to 600torr (preferably 500torr), and a buffer layer with a thickness of 15nm to 35nm (preferably 25nm) is grown on the substrate;

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

The temperature is controlled to be 1000°C to 1200°C (preferably 1100°C), the pressure is 100torr to 500torr (preferably 300torr), and an N-type semiconductor layer with a thickness of 1 μm to 5 μm (preferably 3 μm) is grown on the buffer layer. The doping concentration of the N-type dopant in the layer is 10 ¹⁸ cm ^-3 to 10 ¹⁹ cm ^-3 (preferably 5*10 ¹⁸ cm ^-3 );

The control pressure is 100torr to 500torr (preferably 300torr), and the active layer is grown on the N-type semiconductor layer, and the active layer includes multiple quantum wells and multiple quantum barriers grown alternately; the number of quantum wells is the same as the number of quantum barriers , the number of quantum barriers is 5 to 15 (preferably 10); the thickness of the quantum well is 2.5 nm to 3.5 nm (preferably 3 nm), and the growth temperature of the quantum well is 720 ° C to 829 ° C (preferably 770 ° C ); the thickness of the quantum barrier is 9nm to 20nm (preferably 15nm), and the growth temperature of the quantum barrier is 850°C to 959°C (preferably 900°C);

Control the temperature to be 850°C to 1080°C (preferably 960°C), the pressure to be 100torr to 300torr (preferably 200torr), and to grow a P-type semiconductor layer with a thickness of 100nm to 800nm (preferably 450nm) on the active layer, P-type The doping concentration of the P-type dopant in the semiconductor layer is 10 ¹⁸ cm ^-3 to 10 ¹⁹ cm ^-3 (preferably 5*10 ¹⁸ cm ^-3 );

The temperature is controlled to be 850°C to 1050°C (preferably 950°C), the pressure is 100torr to 300torr (preferably 200torr), and a contact layer with a thickness of 5nm to 300nm (preferably 150nm) is grown on the P-type semiconductor layer.

Specifically, the material of the substrate can be sapphire with a [0001] crystal orientation, and the material of the buffer layer can be gallium nitride (GaN). The material of the N-type semiconductor layer can be N-type doped gallium nitride. The material of the quantum well can be indium gallium nitride (InGaN), and the material of the quantum barrier can be gallium nitride. The material of the P-type semiconductor layer can be P-type doped gallium nitride. The material of the P-type contact layer can be P-type doped indium gallium nitride.

Optionally, before step 101, the preparation method may further include:

The temperature is controlled to be 1000°C to 1200°C (preferably 1100°C), and the substrate is annealed for 1 minute to 10 minutes (preferably 8 minutes) in a hydrogen atmosphere;

The substrate is nitrided.

The above steps are used to clean the surface of the substrate to avoid doping impurities into the epitaxial wafer, affecting the overall crystal quality and reducing the luminous efficiency of the LED.

Optionally, before growing the N-type semiconductor layer on the buffer layer, the preparation method may further include:

The temperature is controlled to be 1000°C to 1100°C (preferably 1050°C), the pressure is 100torr to 500torr (preferably 300torr), and an undoped gallium nitride layer with a thickness of 1 μm to 5 μm (preferably 3 μm) is grown on the buffer layer.

Accordingly, the N-type semiconductor layer is grown on the undoped gallium nitride layer.

The lattice mismatch between the substrate and the N-type semiconductor layer is alleviated by using the undoped gallium nitride layer.

In a specific implementation, the buffer layer is a thin layer of gallium nitride that is first grown on the substrate at a low temperature, so it is also called a low temperature buffer layer. Then, the longitudinal growth of gallium nitride in the low temperature buffer layer will form multiple independent three-dimensional island structures, which are called three-dimensional nucleation layers; then nitrogen is carried out on and between all three-dimensional island structures. The lateral growth of gallium nitride forms a two-dimensional planar structure, which is called a two-dimensional recovery layer; finally, a thicker layer of gallium nitride is grown on the two-dimensional growth layer at high temperature, which is called a high-temperature buffer layer. In this embodiment, the three-dimensional nucleation layer, the two-dimensional recovery layer and the high temperature buffer layer are collectively referred to as the undoped gallium nitride layer.

Optionally, before growing the active layer on the N-type semiconductor layer, the preparation method may further include:

The temperature is controlled to be 800°C to 1100°C (preferably 950°C), the pressure is controlled to be 100torr to 500torr (preferably 300torr), and a stress release layer with a thickness of 50nm to 500nm (preferably 100nm) is grown on the N-type semiconductor layer.

Accordingly, the active layer is grown on the stress release layer.

Specifically, the material of the stress release layer can be gallium indium aluminum nitride (AlInGaN), which can effectively release the stress caused by the lattice mismatch between sapphire and gallium nitride, improve the crystal quality of the epitaxial wafer, and improve the luminous efficiency of the LED.

Preferably, the molar content of the aluminum component may be less than 0.2, and the molar content of the indium component may be less than 0.05 to avoid adverse effects.

Optionally, before growing the P-type semiconductor layer on the active layer, the preparation method may further include:

The temperature is controlled to be 850°C to 1080°C (preferably 960°C), the pressure is 200torr to 500torr (preferably 350torr), and an electron blocking layer with a thickness of 50nm to 150nm (preferably 100nm) is grown on the active layer.

Accordingly, the P-type semiconductor layer is grown on the electron blocking layer.

Specifically, the material of the electron blocking layer can be P-type doped aluminum gallium nitride (AlGaN), such as _{AlyGa1 -yN} , 0.1<y<0.5.

Step 102 : irradiating the surface of the contact layer with electrons to increase nitrogen vacancies in the contact layer.

In this embodiment, electron irradiation (English: Electron irradiation) uses high-energy electron beams to irradiate the material to cause displacement of crystal atoms and improve the properties of the material.

In the embodiment of the present invention, by irradiating the surface of the contact layer with electrons, the microstructure of the crystal of the contact layer is changed, the shape and quantity of defects in the contact layer are affected, and more nitrogen vacancies are generated without changing the proportion of nitrogen elements, increasing the Nitrogen vacancies in the contact layer promote the incorporation of P-type dopants, improve the effectiveness of the incorporation of doping elements, change the high impurity state due to heavy doping, improve the mobility of carriers, and improve the electrode and contact The electrical contact of the layers reduces the series resistance and improves the light efficiency of the entire light-emitting diode.

Alternatively, the radiation dose of electron irradiation may be 10 ¹⁶ /cm ² to 10 ²² /cm ² , preferably 10 ¹⁹ /cm ² .

If the radiation dose of electron irradiation is less than 10 ¹⁶ /cm ² , the nitrogen vacancies in the contact layer may not be effectively increased due to the fact that the radiation dose of electron irradiation is too small, and the light efficiency improvement effect of the light-emitting diode is not obvious; If the radiation dose is greater than 10 ²² /cm ² , the main structure of the crystal of the contact layer may be affected due to too much radiation dose of electrical irradiation, and the light efficiency of the light-emitting diode will be reduced instead.

Among them, the radiation dose is the total number of electrons radiated per unit area of the electron-irradiated surface.

Optionally, the temperature of the environment in which the contact layer is irradiated may be 20°C to 150°C, preferably 85°C.

Optionally, the pressure of the environment where the contact layer is placed during electron irradiation may be 5 Torr to 50 Torr, such as 28 Torr.

Optionally, this step 102 may include:

An electron beam provided by a transmission electron microscope (English: Transmission Electron Microscope, TEM for short) is used as a light source to illuminate the surface of the contact layer.

Directly using existing equipment for electron irradiation is simpler and more convenient to implement.

Specifically, a transmission electron microscope may include an electron gun, a condenser lens, a sample chamber, an objective lens, an intermediate mirror, a transmission mirror, and the like. Among them, the electron gun (English: electronic gun) is used to emit electrons, and is composed of a cathode (English: cathode), a grid (English: guid), and an anode (English: anode).

The cathode is the source of free electrons. In TEM, a heating filament (English: filament) is usually used as a cathode, and the material of the filament can be tungsten or lanthanum hexaboride. When a heating current of several amperes flows through the filament, the filament begins to emit free electrons based on the field electron emission or thermionic emission mechanism. Within a certain range, the amount of free electrons emitted by the filament is proportional to the heating current intensity.

The anode is a metal cylinder with an empty center. The anode is below the cathode. When an accelerating voltage of tens of kilovolts or hundreds of kilovolts is applied to the anode, it will have a strong gravitational effect on the free electrons emitted by the heating of the cathode, and make them change from a disordered state to an orderly directional movement, and at the same time Accelerate the free electrons to a certain speed to form a beam to the target surface of the anode. The electron beam current moving in the axis will be shot out of the electron gun through the circular hole in the center of the anode and become the light source for illuminating the sample.

The grid is located between the cathode and anode, near the top of the filament. The grid is a cap-shaped metal object with a small hole in the center for the electron beam to pass through. A negative voltage of 0 to 1000V is applied to the grid (for the cathode), this negative voltage (called grid bias) can make the electron beam converge to the central axis, and at the same time, it also has a negative effect on the emission of free electrons on the filament. certain regulatory inhibition.

When the transmission electron microscope is working, under the action of the filament power supply, the current flows through the filament cathode, causing the filament to heat up. When the heating of the filament reaches above 2500°C, the filament generates free electrons, and the generated free electrons escape from the surface of the filament. At the same time, the accelerating voltage makes the surface of the anode gather dense positive charges, forming a strong positive electric field. Under the action of this positive electric field, free electrons fly out of the electron gun. In addition, adjusting the magnitude of the grid bias voltage can control the magnitude of the electron beam flux.

In practical applications, an electron beam provided by a TEM of 200 kiloelectron volts (English: kilo electron volt, keV for short) can be used as a light source. Further, the power source of the TEM can use a high voltage source of up to 100,000 volts to 300,000 volts. By controlling the heating current of the cathode in the TEM, the accelerating voltage of the anode in the TEM, the grid bias voltage of the grid in the TEM, and the duration of the electron irradiation, the radiation dose of the electron irradiation is 10 ¹⁶ /cm ² -10 ²² /cm ² .

Preferably, the diameter of the electron beam may be 8 μm˜30 μm, preferably 19 μm.

If the diameter of the electron beam is less than 8μm, the electron beam may be too concentrated because the diameter of the electron beam is too small, which will damage the main structure of the contact layer and affect the luminous efficiency of the LED; if the diameter of the electron beam is greater than 30μm, it may be Because the diameter of the electron beam is too large, the electron beam is too scattered, and the nitrogen vacancies in the contact layer cannot be effectively increased, and the light efficiency improvement effect of the light emitting diode is not obvious.

Step 103: Perform annealing treatment on the contact layer. This step 103 is an optional step.

Partial defects and impurity states are eliminated by annealing treatment.

Optionally, the temperature of the annealing treatment may be 700° C.˜900° C., which achieves a better effect.

Optionally, the contact layer may be in a nitrogen atmosphere during the annealing treatment, which achieves a better effect.

Preferably, the vacuum degree of the nitrogen atmosphere can be 10 ^-8 Torr to 10 ^-6 Torr, which is better to achieve.

Optionally, the duration of the annealing treatment may be 15 min to 50 min, which achieves a better effect.

It should be noted that, after the above steps, the temperature is first lowered to 500°C to 900°C (preferably 800°C), and the epitaxial wafer is annealed for 5 minutes to 15 minutes (preferably 10 minutes) in a nitrogen atmosphere , and then the temperature of the epitaxial wafer is lowered to room temperature to end the growth of the epitaxial process.

Controlling temperature and pressure refers to controlling the temperature and pressure in the reaction chamber for growing epitaxial wafers. . High-purity hydrogen, or high-purity nitrogen, or a mixture of hydrogen and nitrogen is used as carrier gas, high-purity ammonia is used as nitrogen source, trimethylgallium or triethylgallium is used as gallium source, and trimethylindium is used as indium source, trimethylaluminum as the aluminum source, silane as the N-type dopant, and MgO as the P-type dopant.

A specific implementation of the preparation method shown in Figure 1 may include:

Step 201 : control the temperature to be 500° C. and the pressure to be 500 torr, and grow a buffer layer with a thickness of 25 nm on the substrate.

Step 202 : control the temperature to be 1100° C., the pressure to be 500 torr, and the duration to be 8 minutes, and perform in-situ annealing treatment on the buffer layer.

Step 203 : controlling the temperature to 1100° C. and the pressure to 300 torr, growing an N-type semiconductor layer with a thickness of 3 μm on the buffer layer, and the doping concentration of the N-type dopant in the N-type semiconductor layer is 5*10 ¹⁸ cm ⁻³ .

Step 204 : the control pressure is 300torr, and the active layer is grown on the N-type semiconductor layer. The active layer includes 10 quantum wells and 10 quantum barriers grown alternately; the thickness of the quantum wells is 3nm, and the growth temperature of the quantum wells is 770 ℃; the thickness of the quantum barrier is 15nm, and the growth temperature of the quantum barrier is 900℃.

Step 205 : control the temperature to be 960° C. and the pressure to be 200 torr, and grow a P-type semiconductor layer with a thickness of 450 nm on the active layer. The doping concentration of the P-type dopant in the P-type semiconductor layer is 5*10 ¹⁸ cm ⁻³ .

Step 206 : control the temperature to be 950° C. and the pressure to be 200 torr, and grow a contact layer with a thickness of 150 nm on the P-type semiconductor layer.

Step 207 : irradiating the surface of the contact layer with electrons to increase nitrogen vacancies in the contact layer, and the radiation dose of the electron irradiation is 10 ¹⁶ /cm ² .

The obtained epitaxial wafer is made into a chip, and the light efficiency of the chip is improved by 3% to 5% compared with that without electron irradiation.

Another specific implementation of the preparation method shown in Figure 1 may include:

Step 301 : control the temperature to be 500° C. and the pressure to be 500 torr, and grow a buffer layer with a thickness of 25 nm on the substrate.

Step 302 : control the temperature to be 1100° C., the pressure to be 500 torr, and the duration to be 8 minutes, and perform in-situ annealing treatment on the buffer layer.

Step 303 : control the temperature to be 1100° C. and the pressure to be 300 torr, grow an N-type semiconductor layer with a thickness of 3 μm on the buffer layer, and the doping concentration of the N-type dopant in the N-type semiconductor layer is 5*10 ¹⁸ cm ⁻³ .

Step 304 : the control pressure is 300torr, and the active layer is grown on the N-type semiconductor layer, and the active layer includes 10 quantum wells and 10 quantum barriers grown alternately; the thickness of the quantum wells is 3nm, and the growth temperature of the quantum wells is 770 ℃; the thickness of the quantum barrier is 15nm, and the growth temperature of the quantum barrier is 900℃.

Step 305 : controlling the temperature to be 960° C. and the pressure of 200 torr, growing a P-type semiconductor layer with a thickness of 450 nm on the active layer, and the doping concentration of the P-type dopant in the P-type semiconductor layer is 5*10 ¹⁸ cm ⁻³ .

Step 306 : control the temperature to be 950° C. and the pressure to be 200 torr, and grow a contact layer with a thickness of 150 nm on the P-type semiconductor layer.

Step 307 : irradiating the surface of the contact layer with electrons to increase nitrogen vacancies in the contact layer, and the radiation dose of the electron irradiation is 10 ¹⁹ /cm ² .

The obtained epitaxial wafer is made into a chip, and the light efficiency of the chip is increased by 4% to 7% compared with that without electron irradiation.

Another specific implementation of the preparation method shown in Figure 1 may include:

Step 401 : control the temperature to be 500° C. and the pressure to be 500 torr, and grow a buffer layer with a thickness of 25 nm on the substrate.

Step 402 : control the temperature to be 1100° C., the pressure to be 500 torr, and the duration to be 8 minutes, and perform in-situ annealing treatment on the buffer layer.

Step 403 : control the temperature to 1100° C. and the pressure to 300 torr, grow an N-type semiconductor layer with a thickness of 3 μm on the buffer layer, and the doping concentration of the N-type dopant in the N-type semiconductor layer is 5*10 ¹⁸ cm ⁻³ .

Step 404: control the pressure to 300torr, grow an active layer on the N-type semiconductor layer, the active layer includes 10 quantum wells and 10 quantum barriers grown alternately; the thickness of the quantum wells is 3nm, and the growth temperature of the quantum wells is 770 ℃; the thickness of the quantum barrier is 15nm, and the growth temperature of the quantum barrier is 900℃.

Step 405 : control the temperature to be 960° C. and the pressure to be 200 torr, and grow a P-type semiconductor layer with a thickness of 450 nm on the active layer. The doping concentration of the P-type dopant in the P-type semiconductor layer is 5*10 ¹⁸ cm ⁻³ .

Step 406 : control the temperature to be 950° C. and the pressure to be 200 torr, and grow a contact layer with a thickness of 150 nm on the P-type semiconductor layer.

Step 407 : irradiating the surface of the contact layer with electrons to increase nitrogen vacancies in the contact layer, and the radiation dose of the electron irradiation is 10 ²² /cm ² .

The obtained epitaxial wafer is made into a chip, and the light efficiency of the chip is increased by 2% to 4% compared with that without electron irradiation.

The embodiment of the present invention provides a light-emitting diode epitaxial wafer, which is suitable for being prepared by the preparation method shown in FIG. 1 . 2 is a schematic structural diagram of a light-emitting diode epitaxial wafer provided by an embodiment of the present invention. Referring to FIG. 2, the light-emitting diode epitaxial wafer includes a substrate 10, a buffer layer 20, an N-type semiconductor layer 30, an active Layer 40 , P-type semiconductor layer 50 and contact layer 60 , buffer layer 20 , N-type semiconductor layer 30 , active layer 40 , P-type semiconductor layer 50 and contact layer 60 are sequentially stacked on substrate 10 .

In this embodiment, the surface of the contact layer 60 is a surface treated by electron irradiation.

Specifically, the material of the substrate 10 can be sapphire. The material of the buffer layer 20 may be gallium nitride (GaN). The material of the N-type semiconductor layer 30 can be N-type doped gallium nitride. The active layer 40 may 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 may be indium gallium nitride (InGaN), and the material of the quantum barriers may be nitrogen gallium. The material of the P-type semiconductor layer 50 may be P-type doped gallium nitride. The material of the contact layer 60 can be P-type doped indium gallium nitride.

More specifically, the thickness of the buffer layer 20 may be 15 nm to 35 nm (preferably 25 nm). The thickness of the N-type semiconductor layer 30 may be 1 μm˜5 μm (preferably 3 μm), and the doping concentration of the N-type dopant in the N-type semiconductor layer 30 is 10 ¹⁸ cm ^{−3 ˜10 19} cm ⁻³ (preferably 5* 10 ¹⁸ cm ^-3 ). The number of quantum wells is the same as the number of quantum barriers, and the number of quantum barriers can be 5 to 15 (preferably 10); the thickness of the quantum wells can be 2.5 nm to 3.5 nm (preferably 3 nm), and the thickness of the quantum barriers It may be 9 nm to 20 nm (preferably 15 nm). The thickness of the P-type semiconductor layer 60 may be 100 nm to 800 nm (preferably 450 nm), and the doping concentration of the P-type dopant in the P-type semiconductor layer 50 is 10 ¹⁸ cm ⁻³ to 10 ¹⁹ cm ⁻³ (preferably 5* 10 ¹⁸ cm ^-3 ). The thickness of the contact layer 60 may be 5 nm to 300 nm (preferably 150 nm).

Optionally, as shown in FIG. 2 , the light-emitting diode epitaxial wafer may further include an undoped gallium nitride layer 70 , and the undoped gallium nitride layer 70 is disposed between the buffer layer 20 and the N-type semiconductor layer 30 to The lattice mismatch between the substrate and the N-type semiconductor layer is alleviated.

Specifically, the thickness of the undoped gallium nitride layer 70 may be 1 μm˜5 μm (preferably 3 μm).

Optionally, as shown in FIG. 2 , the light emitting diode epitaxial wafer may further include a stress release layer 80, and the stress release layer 80 is disposed between the N-type semiconductor layer 30 and the active layer 40 to release the sapphire and gallium nitride crystals. stress due to lattice mismatch.

Specifically, the material of the stress release layer 80 may be gallium indium aluminum nitride (AlInGaN); the molar content of the aluminum component may be less than 0.2, and the molar content of the indium component may be less than 0.05; the thickness of the stress release layer 80 may be 50 nm ~500nm (preferably 100nm).

Optionally, as shown in FIG. 2 , the light emitting diode epitaxial wafer may further include an electron blocking layer 90 , and the electron blocking layer 90 is disposed between the active layer 40 and the P-type semiconductor layer 50 to prevent electrons from transitioning to the P-type semiconductor layer. The non-radiative recombination with holes in the layer reduces the luminous efficiency of the LED.

Specifically, the material of the electron blocking layer 90 can be P-type doped aluminum gallium nitride (AlGaN), such as _{AlyGa1 -yN} , 0.1<y<0.5; the thickness of the electron blocking layer 90 can be 50nm˜150nm (preferably 100 nm).

The above 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 the range.

Claims (8)

1. A preparation method of a light emitting diode epitaxial wafer is characterized by comprising the following steps:

growing a buffer layer, an N-type semiconductor layer, an active layer, a P-type semiconductor layer and a contact layer on a substrate in sequence by adopting a chemical vapor deposition technology, wherein the contact layer is P-type doped nitride;

performing electron irradiation on the surface of the contact layer to increase nitrogen vacancies in the contact layer; the electron irradiation is to irradiate the material by adopting a high-energy electron beam, the electron beam is provided by a transmission electron microscope with 200 kilo-electron volts, and the power supply voltage of the transmission electron microscope is 10-30 kilo-volts; increasing nitrogen vacancies in the contact layer for facilitating incorporation of the P-type dopant;

and annealing the contact layer.

2. The production method according to claim 1, wherein the electron irradiation is performed at a radiation dose of 10¹⁶/cm²～10²²/cm²。

3. The production method according to claim 1 or 2, wherein the diameter of the electron beam is 8 μm to 30 μm.

4. The production method according to claim 1 or 2, wherein the temperature of the annealing treatment is 700 ℃ to 900 ℃.

5. The production method according to claim 1 or 2, characterized in that the contact layer is in a nitrogen atmosphere when the annealing treatment is performed.

6. The production method according to claim 5, wherein the nitrogen atmosphere has a degree of vacuum of 10^-8Torr～10^-6Torr。

7. The production method according to claim 1 or 2, wherein the duration of the annealing treatment is 15 to 50 min.

8. The light-emitting diode epitaxial wafer comprises a substrate, a buffer layer, an N-type semiconductor layer, an active layer, a P-type semiconductor layer and a contact layer, wherein the buffer layer, the N-type semiconductor layer, the active layer, the P-type semiconductor layer and the contact layer are sequentially laminated on the substrate; the electron irradiation is to irradiate the material by adopting a high-energy electron beam, the electron beam is provided by a transmission electron microscope with 200 kilo-electron volts, and the power supply voltage of the transmission electron microscope is 10-30 kilo-volts; increasing nitrogen vacancies in the contact layer for facilitating incorporation of the P-type dopant.

Images