CN112151645A - Preparation of large-angle oblique-cutting sapphire substrate AlN, light-emitting diode and preparation method thereof - Google Patents

Abstract

The invention discloses a preparation of AlN of a large-angle chamfered sapphire substrate, a light-emitting diode and a preparation method thereof. The preparation method of the AlN of a large-angle chamfered sapphire substrate comprises: selecting a large-angle chamfered sapphire substrate and a conventional sapphire substrate; The AlN layer was grown on the large-angle chamfered sapphire substrate and the conventional sapphire substrate to obtain the large-angle chamfered AlN epitaxial layer on the sapphire substrate and the conventional sapphire substrate AlN epitaxial layer; The growth surface is attached to the AlN growth surface of the AlN epitaxial layer of the conventional sapphire substrate, and high-temperature annealing is performed; the AlN layer and high-temperature annealing treatment are repeated on the large-angle chamfered AlN epitaxial layer of the sapphire substrate after high-temperature annealing until high-temperature annealing. The large-angle chamfering of the AlN layer on the AlN epitaxial layer of the sapphire substrate reaches a preset thickness. The invention prepares high-quality AlN thin films on the large-angle chamfered sapphire substrate by annealing the large-angle chamfered sapphire substrate after growing the AlN thin film.

Description

Preparation of AlN, light-emitting diode and preparation method of large-angle chamfered sapphire substrate

technical field

The invention belongs to the technical field of wide-bandgap semiconductors, and in particular relates to a method for preparing AlN of a large-angle chamfered sapphire substrate, a method for preparing a light-emitting diode, and a light-emitting diode.

Background technique

In the prior art, the AlGaN-based solid-state deep ultraviolet light source has the advantages of environmental protection and long working life, and is the key technology to replace the traditional mercury lamp. As a wide-bandgap semiconductor, AlGaN has been proven to be one of the ideal choices for a clean and environmentally friendly deep ultraviolet (Deep Ultraviolet, DUV) light source.

Compared with the mature technology of blue LED based on InGaN, the external quantum efficiency of AlGaN-based deep ultraviolet light emitting diode (DUV-LED) is lower than 10% in most cases. The large-angle chamfering of the substrate can increase the electron wave function overlap and enhance the carrier localization. The large-angle chamfering of the substrate is very necessary to improve the radiative recombination efficiency and the internal quantum efficiency. The mesa density can be effectively reduced by increasing the substrate chamfering angle, which helps atoms to be effectively incorporated into the step sites even at smaller migration lengths. The epitaxial structure based on the large-angle chamfered substrate has many advantages, and there are many methods to prepare AlN thin films on the traditional C-plane sapphire substrate, including continuous high-temperature growth based on metal organic vapor phase growth, hydride vapor phase epitaxy (Hydride vapor phase epitaxy). Vapor Phase Epitaxy, referred to as HVPE) and molecular beam epitaxy.

However, the most critical problem is still the epitaxial growth of AlN. The above methods cannot solve the problem that the dislocation density and surface morphology of the AlN structure epitaxially grown on the large-angle bevel sapphire will deteriorate. The preparation of AlN requires high temperature and high pressure equipment and precise flow control systems. At present, the crystal quality prepared by the expensive commercial high temperature metal organic chemical vapor deposition (High Temperature Metal Organic Chemical Vapor Deposition, referred to as HT-MOCVD) still has a lot of room for improvement, and the lattice constants of AlN materials and sapphire substrates are very different. There is a large thermal mismatch, which makes the AlN surface extremely prone to cracks, and the development of deep ultraviolet devices on a large-angle bevel cut sapphire substrate is greatly restricted.

SUMMARY OF THE INVENTION

In order to solve the above problems existing in the prior art, the present invention provides a method for preparing AlN of a large-angle chamfered sapphire substrate, a method for preparing a light-emitting diode, and a light-emitting diode.

An embodiment of the present invention provides a method for preparing AlN of a large-angle beveled sapphire substrate, and the method for preparing the AlN of a large-angle beveled sapphire substrate includes:

Select a large angle to chamfer the sapphire substrate, a conventional sapphire substrate;

growing an AlN layer on the large-angle chamfered sapphire substrate to obtain a large-angle chamfered sapphire substrate AlN epitaxial layer, and growing the AlN layer on the conventional sapphire substrate to obtain a conventional sapphire substrate AlN epitaxial layer;

The AlN growth surface of the large-angle chamfered AlN epitaxial layer of the sapphire substrate is attached to the AlN growth surface of the conventional sapphire substrate AlN epitaxial layer, and placed in a high-temperature annealing furnace for high-temperature annealing. The high-angle chamfering of the AlN epitaxial layer on the sapphire substrate and the peeling of the AlN epitaxial layer on the conventional sapphire substrate;

Repeatedly growing an AlN layer and high temperature annealing on the AlN epitaxial layer of the large-angle chamfered sapphire substrate after high-temperature annealing until the AlN layer on the AlN epitaxial layer of the large-angle chamfered sapphire substrate after the high-temperature annealing reaches a preset thickness , to complete the preparation of large-angle chamfered sapphire substrate AlN.

In an embodiment of the present invention, the chamfering direction of the large-angle chamfered sapphire substrate is that the c-plane deviates from the a-plane, and the chamfering angle ranges from 0.2° to 6°;

In an embodiment of the present invention, the thickness of the AlN layer grown on the large-angle chamfered sapphire substrate is 200 nm˜400 nm.

In an embodiment of the present invention, the thickness of the AlN layer grown on the conventional sapphire substrate is 200 nm˜300 nm.

In one embodiment of the present invention, the AlN growth surface of the AlN epitaxial layer of the large-angle chamfered sapphire substrate is attached to the AlN growth surface of the AlN epitaxial layer of the conventional sapphire substrate, and placed in a high-temperature annealing furnace Performing high temperature annealing includes:

The AlN growth surface of the AlN epitaxial layer of the AlN epitaxial layer of the sapphire substrate with the large angle beveled and the AlN growth surface of the AlN epitaxial layer of the conventional sapphire substrate are attached up and down, and placed in a high temperature annealing furnace, wherein the large angle oblique The AlN growth surface of the AlN epitaxial layer of the cut sapphire substrate is on the bottom, and the AlN growth surface of the AlN epitaxial layer on the conventional sapphire substrate is on the top. Process conditions: nitrogen and argon are introduced into the high-temperature annealing furnace, and nitrogen and argon are introduced into the annealing furnace. The gas volume ratio is 3:1, and the pressure in the high-temperature annealing furnace is maintained at 0.03 to 0.6 atmospheres; the temperature of the high-temperature annealing furnace is raised to 1600 ° C to 1750 ° C, and the high temperature annealing treatment is carried out for 1 h to 3 hours; Cool to room temperature.

In an embodiment of the present invention, the time for rapidly cooling the high temperature annealing furnace to room temperature is controlled within 0.5h to 1.5h.

In an embodiment of the present invention, the preset thickness of the AlN layer of the large-angle chamfered AlN epitaxial layer of the sapphire substrate is 0.2 μm˜5 μm.

Another embodiment of the present invention provides a method for fabricating a light-emitting diode, and the method for fabricating the light-emitting diode includes:

A large-angle chamfered sapphire substrate AlN epitaxial layer is prepared by any of the above-mentioned methods for preparing AlN on a large-angle chamfered sapphire substrate, and the thickness of the AlN layer of the large-angle chamfered sapphire substrate AlN epitaxial layer is a preset thickness ;

growing an AlN homoepitaxial layer on the AlN growth surface of the AlN epitaxial layer of the large-angle chamfered sapphire substrate;

growing an n-type AlGaN layer on the AlN homoepitaxial layer;

growing an AlGaN/AlN multiple quantum well layer on the n-type AlGaN layer;

growing an AlGaN electron blocking layer on the AlGaN/AlN multiple quantum well layer;

growing a p-type AlGaN layer on the AlGaN electron blocking layer;

Part of the p-type AlGaN layer is etched to the n-type AlGaN layer by an inductively coupled plasma etching process to form an n-type AlGaN mesa, and a metal sputtering method is used to deposit n-type electrodes on the n-type AlGaN mesa, respectively, A p-type electrode is deposited on another part of the p-type AlGaN layer to complete the preparation of the light-emitting diode.

In an embodiment of the present invention, the chamfering direction of the large-angle chamfered sapphire substrate is that the c-plane deviates from the a-plane, and the chamfering angle ranges from 0.2° to 6°.

Yet another embodiment of the present invention provides a light-emitting diode prepared by any of the above-mentioned methods for preparing a light-emitting diode.

Compared with the prior art, the beneficial effects of the present invention:

The method for preparing AlN of a large-angle chamfered sapphire substrate provided by the present invention prepares a high-quality AlN film on the large-angle chamfered sapphire substrate by annealing the large-angle chamfered sapphire substrate after growing the AlN film. , so as to obtain a large-angle chamfered sapphire/AlN with low dislocation density, smooth surface and good uniformity as a template, which effectively overcomes the problems of high AlN dislocation density and poor surface roughness in the existing AlN growth technology.

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

Description of drawings

1 is a schematic flowchart of a method for preparing AlN of a large-angle chamfered sapphire substrate provided in an embodiment of the present invention;

Fig. 2 is a kind of ultraviolet transmission spectrum test schematic diagram provided by the embodiment of the present invention;

3 is a schematic diagram showing the comparison of the test results of the rocking curve of the X-ray diffraction (002) plane of the AlN epitaxial layer prepared by the present invention and the AlN epitaxial layer prepared by traditional PVD provided by the embodiment of the present invention;

4 is a schematic diagram showing the comparison of the test results of the rocking curve of the X-ray diffraction (102) plane of the AlN epitaxial layer prepared by the present invention and the AlN epitaxial layer prepared by traditional PVD provided by the embodiment of the present invention;

5 is a schematic flowchart of a method for manufacturing a light-emitting diode according to an embodiment of the present invention;

6 is a schematic diagram showing the comparison of the test results of the rocking curve of the X-ray diffraction (002) plane of the n-type AlGaN layer regrown on the high-temperature annealed AlN layer in the preparation method of the light-emitting diode provided by the embodiment of the present invention;

7 is a schematic diagram showing the comparison of the test results of the rocking curve of the X-ray diffraction (102) plane of the n-type AlGaN layer regrown on the high-temperature annealed AlN layer in the preparation method of the light-emitting diode provided by the embodiment of the present invention;

FIG. 8 is a schematic structural diagram of a light emitting diode according to an embodiment of the present invention.

Description of reference numbers:

1-AlN epitaxial layer on sapphire substrate with large angle chamfering; 2-AlN homoepitaxial layer; 3-n-type AlGaN layer; 4-AlGaN/AlN multiple quantum well layer; 5-AlGaN electron blocking layer; 6-p-type AlGaN layer; 7-n electrode; 8-p electrode.

Detailed ways

The present invention will be described in further detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

Example 1

In order to solve the problem that the dislocation density and surface morphology of the epitaxially grown AlN structure on the large-angle chamfered sapphire substrate will deteriorate, please refer to FIG. 1. FIG. 1 is a large-angle chamfered sapphire substrate provided by an embodiment of the present invention. Schematic flow diagram of the bottom AlN preparation method. The present embodiment provides a method for preparing AlN of a large-angle beveled sapphire substrate, and the method for preparing the AlN of a large-angle beveled sapphire substrate includes the following steps:

Step 1. Select a large angle to chamfer a sapphire substrate, a conventional sapphire substrate.

Specifically, in this embodiment, a large-angle chamfered sapphire substrate and a conventional sapphire substrate are selected, and the large-angle chamfered sapphire substrate and the conventional sapphire substrate are respectively pretreated, including: the large-angle chamfered sapphire substrate The bottom and the conventional sapphire substrate were ultrasonically cleaned with acetone, dilute hydrochloric acid and deionized water in turn, and then placed in the reaction chamber of a physical vapor deposition (Physical Vapour Deposition, PVD for short) device, and the vacuum degree of the reaction chamber was reduced to 1×10 ^{− 2} Torr, pass hydrogen into the reaction chamber, under the condition of the reaction chamber pressure of PVD device 200 Torr, heat the large-angle chamfered sapphire substrate and the conventional sapphire substrate to a temperature of 950 ℃ ~ 1100 ℃, and keep it for 10min, complete the large-angle bevel cut sapphire substrate and the conventional sapphire substrate. Heat treatment of angle-cut sapphire substrates and conventional sapphire substrates.

Preferably, the chamfering direction of the large-angle chamfering of the sapphire substrate is that the c-plane deviates from the a-plane, and the chamfering angle ranges from 0.2° to 6°.

Step 2, growing an AlN layer on a large-angle chamfered sapphire substrate to obtain an AlN epitaxial layer on a large-angle chamfered sapphire substrate, and growing an AlN layer on a conventional sapphire substrate to obtain an AlN epitaxial layer on a conventional sapphire substrate.

Specifically, in this example, the atmosphere in the reaction chamber of the PVD device is replaced with high-purity nitrogen (the nitrogen content is 99.999%), and the distances between the large-angle chamfered sapphire substrate, the conventional sapphire substrate and the target are adjusted to 4 cm. ~6cm, the temperature of the large-angle chamfered sapphire substrate and the conventional sapphire substrate were kept at 620-700 °C, and the radio frequency power was adjusted to 710W ~ 750W by the method of radio frequency magnetron sputtering, and physical sputtering was performed on the large-angle chamfered sapphire substrate respectively. The AlN layer is grown by sputtering to obtain an AlN epitaxial layer on a sapphire substrate with a large angle chamfer, and the AlN epitaxial layer is obtained by physical sputtering growth on a conventional sapphire substrate. Among them, the AlN layer grown on the large-angle chamfered sapphire substrate and the AlN layer grown on the conventional sapphire substrate are both unintentionally doped AlN layers; the physical sputtering growth of the AlN layer on the conventional sapphire substrate is specifically An AlN layer was grown by physical sputtering on the c-plane of a conventional sapphire substrate.

Preferably, the thickness of the AlN layer grown on the large-angle chamfered sapphire substrate is 200 nm˜400 nm, and the thickness of the AlN layer grown on the conventional sapphire substrate is 200 nm˜300 nm.

Step 3. Attach the AlN growth surface of the AlN epitaxial layer of the sapphire substrate at a large angle to the AlN growth surface of the AlN epitaxial layer of the conventional sapphire substrate, and place it in a high-temperature annealing furnace for high-temperature annealing. The AlN epitaxial layer of the sapphire substrate is chamfered at a large angle, and the AlN epitaxial layer of the conventional sapphire substrate is peeled off.

Specifically, in this embodiment, the AlN growth surface of the AlN epitaxial layer of the sapphire substrate is chamfered at a large angle and the AlN growth surface of the AlN epitaxial layer of the conventional sapphire substrate is attached up and down, and the crystal orientation of the AlN epitaxial layer is kept consistent and placed in a high temperature retreat. In the furnace, the AlN growth surface of the AlN epitaxial layer of the sapphire substrate is cut at a large angle at the bottom, and the AlN growth surface of the AlN epitaxial layer of the conventional sapphire substrate is on the top. The volume ratio of nitrogen and argon introduced is 3:1, and the pressure in the high-temperature annealing furnace is maintained at 0.03 to 0.6 atmospheres; the temperature of the high-temperature annealing furnace is raised to 1600 ° C to 1750 ° C, and the high temperature annealing treatment is carried out for 1 h to 3 h; After completion, the high temperature annealing furnace is rapidly cooled to room temperature. Preferably, the time for rapidly cooling the high temperature annealing furnace to room temperature is controlled within 0.5h to 1.5h.

The AlN epitaxial layer and the c-plane sapphire AlN epitaxial layer on the c-plane sapphire AlN epitaxial layer after high-temperature annealing and cooling are separated from the top and bottom, and the AlN growth surface of the AlN epitaxial layer on the sapphire substrate and the AlN epitaxial layer of the conventional sapphire substrate are respectively maintained at a large angle. The AlN growth side of the epitaxial layer faces up for subsequent reuse.

Step 4. Repeat the growth of the AlN layer and the high-temperature annealing on the AlN epitaxial layer of the large-angle chamfered sapphire substrate after high-temperature annealing until the AlN layer on the AlN epitaxial layer of the large-angle chamfered sapphire substrate after high-temperature annealing reaches a preset value thickness to complete the preparation of AlN on the sapphire substrate with a large angle bevel.

Specifically, in this embodiment, the large-angle chamfered AlN epitaxial layer of the sapphire substrate obtained in the above step 3 is placed in a PVD device to re-sputter the AlN layer, and the high-temperature annealing furnace is subjected to high-temperature annealing treatment, and the processes of steps 2 and 3 are repeated. A high-quality large-angle chamfered AlN epitaxial layer on a sapphire substrate with a preset thickness is obtained. Wherein, the thickness of the AlN layer sputtered on the AlN epitaxial layer of the sapphire substrate after high-temperature annealing is 200 nm to 400 nm, and the high-temperature annealing treatment adopts the annealing parameters of step 3 to complete each AlN layer sputtering, High-temperature annealing is performed until the thickness of the AlN epitaxial layer of the sapphire substrate is chamfered at a large angle and reaches a preset thickness.

Preferably, the preset thickness of the AlN layer of the AlN epitaxial layer of the sapphire substrate is chamfered at a large angle to be 0.2 μm˜5 μm.

The effect of the AlN preparation method of the large-angle chamfered sapphire substrate proposed in this embodiment can be further illustrated by the following test results:

1. Test conditions:

The 800nm AlN epitaxial layer on the sapphire substrate with the c-plane deviated from the a-plane by 4° was selected at room temperature of 25°C in a nitrogen atmosphere.

2. Test content:

Test 1. Please refer to Fig. 2. Fig. 2 is a schematic diagram of a UV transmission spectrum test provided by the embodiment of the present invention. In Fig. 2, the abscissa is the laser incident wavelength unit of the UV transmission spectrum. The unit is nm, and the ordinate of Fig. 2 is the light transmission. In this embodiment, the 800nm AlN epitaxial layer on the sapphire substrate with the c-plane deviated to the a-plane by 4° is selected to carry out the ultraviolet transmission spectrum test. It can be observed from FIG. 2 that the c-plane deviation obtained by the preparation method of this embodiment is The 800nm AlN epitaxial layer on the 4° sapphire substrate is chamfered on the a-plane, the thickness is accurately controlled, the spectral curve is smooth, and the deep ultraviolet light transmittance near 280nm is good.

Test 2. Please refer to FIG. 3. FIG. 3 is a schematic diagram showing the comparison of the test results of the rocking curve of the X-ray diffraction (002) plane between the AlN epitaxial layer prepared by the present invention and the AlN epitaxial layer prepared by traditional PVD provided by the embodiment of the present invention, FIG. 3 The middle abscissa is the Omega angle and the unit is arcsec, and the ordinate in Figure 3 is the peak intensity after normalization. In this embodiment, the X-ray diffraction of the 800nm AlN epitaxial layer on the sapphire substrate with the c-plane deviated to the a-plane by 4° is selected. The (002) plane rocking curve is tested, and it can be observed from FIG. 3 that the c-plane biased to the a-plane obliquely cut 4° by the preparation method of this embodiment on the 800nm AlN epitaxial film (002) plane rocking curve half height on the sapphire substrate The width is only 98arcsec, which is far lower than 1211arcsec prepared by traditional PVD method, the crystal quality is significantly improved, and the screw dislocation density is significantly reduced. Among them, 002 refers to the Miller index of a specific crystal plane of AlN crystal.

Test 3. Please refer to FIG. 4. FIG. 4 is a schematic diagram of the comparison of the test results of the rocking curve of the X-ray diffraction (102) plane between the AlN epitaxial layer prepared by the present invention and the AlN epitaxial layer prepared by traditional PVD provided by the embodiment of the present invention, FIG. 4 The middle abscissa is the Omega angle and the unit is arcsec, and the ordinate in Figure 4 is the peak intensity after normalization. In this embodiment, the X-ray diffraction of the 800nm AlN epitaxial layer on the sapphire substrate with the c-plane deviated to the a-plane by 4° is selected. The (102) plane rocking curve is tested, and it can be observed from Figure 4 that the c-plane biased to the a-plane obliquely cut at 4° on the sapphire substrate prepared by the preparation method of this embodiment has a half height of the (102) plane rocking curve of the 800nm AlN epitaxial film on the sapphire substrate. The width is only 335arcsec, which is far lower than 1810arcsec prepared by traditional PVD method. The crystal quality is significantly improved, and the edge dislocation density is significantly reduced. Among them, 102 refers to the Miller index of a specific crystal plane of AlN crystal.

To sum up, the preparation method of AlN on a large-angle chamfered sapphire substrate proposed in this embodiment realizes high-quality growth of an AlN epitaxial layer on a large-angle chamfered sapphire substrate by adjusting the annealing process parameters after the physical growth of the AlN film. Thus, a large-angle chamfered sapphire/AlN with low dislocation density, smooth surface and good uniformity is obtained as a template. Based on this template, AlGaN related devices are grown, which effectively overcomes the high dislocation density of AlN in the existing AlN growth technology. At the same time, the AlN preparation method of the large-angle chamfered sapphire substrate in this embodiment is still an epitaxial technology, and the preparation can be carried out only by adjusting the annealing parameters, no special requirements for the growth equipment, simple application and low price. .

Embodiment 2

On the basis of Embodiment 1 above, please refer to FIG. 5 , which is a schematic flowchart of a method for manufacturing a light emitting diode according to an embodiment of the present invention. This embodiment provides a method for preparing a light-emitting diode, and the method for preparing a light-emitting diode includes the following steps:

Step 1. Prepare an AlN epitaxial layer of a large-angle chamfered sapphire substrate.

Specifically, in this embodiment, the AlN epitaxial layer of the large-angle chamfered sapphire substrate is prepared by the method for preparing the large-angle chamfered sapphire substrate AlN described in the first embodiment, and the large-angle chamfered AlN of the sapphire substrate is not repeated here. For the preparation process of the epitaxial layer and its technical effect, please refer to Embodiment 1 for details. The thickness of the AlN epitaxial layer of the large-angle chamfered sapphire substrate is a preset thickness.

Preferably, the chamfering direction of the large-angle chamfering of the sapphire substrate is that the c-plane deviates from the a-plane, and the chamfering angle ranges from 0.2° to 6°.

Preferably, the preset thickness of the AlN layer of the AlN epitaxial layer of the sapphire substrate is chamfered at a large angle to be 0.2 μm˜5 μm.

Step 2, growing an AlN homoepitaxial layer on the AlN growth surface of the AlN epitaxial layer of the sapphire substrate chamfered at a large angle.

Specifically, in this embodiment, the c-plane biased to a-plane chamfered AlN epitaxial layer of the sapphire substrate after high temperature annealing is placed in a metal-organic chemical vapor deposition (Metal-Organic Chemical Vapour Deposition, MOCVD for short) device, and the MOCVD device reacts The room temperature was raised to 1120-1350°C, the pressure of the reaction chamber was adjusted to 85mbar, TMAl and ammonia were passed in and the V/III molar ratio was kept at 435 to grow an AlN homoepitaxial layer with a thickness of 0.5μm to 1μm.

Step 3, growing an n-type AlGaN layer on the AlN homoepitaxial layer.

Specifically, in this embodiment, the MOCVD process is used on the AlN homoepitaxial layer, and under the condition that the temperature of the reaction chamber is 1085°C, ammonia gas with a flow rate of 995 sccm, a gallium source with a flow rate of 49 sccm, and a flow rate of 52 sccm are introduced at the same time. The three gases of the aluminum source are used to grow an n-type AlGaN layer with a thickness of 1.5 μm to 2.5 μm under the condition of maintaining a pressure of 30 Torr. Among them, Si doping can be performed in the growing n-type AlGaN layer, and the Si doping concentration is 5×10 ¹⁸ cm ^-3 .

Step 4, growing an AlGaN/AlN multiple quantum well layer on the n-type AlGaN layer.

Specifically, in this embodiment, the MOCVD process is used on the n-type AlGaN layer, and the LED active region is grown at 1020° C. and 1120° C. in a nitrogen atmosphere, respectively. Repeat the above conditions for 8 cycles to obtain a thickness of 110 nm~ 150nm AlGaN/AlN quantum well barrier.

Step 5, growing an AlGaN electron blocking layer on the AlGaN/AlN multiple quantum well layer.

Specifically, in this embodiment, the temperature of the nitrogen atmosphere in the reaction chamber is kept to 1180° C., and the MOCVD process is used to grow an AlGaN electron blocking layer with a thickness of 35 nm to 45 nm.

Step 6, growing a p-type AlGaN layer on the AlGaN electron blocking layer.

Specifically, in this embodiment, MOCVD process is used on the AlGaN electron blocking layer, the reaction chamber is replaced with a hydrogen atmosphere, the temperature of the reaction chamber is raised to 985° C., the pressure of the reaction chamber is kept at 135 Torr, and the ammonia with a flow rate of 1175 sccm is introduced into the reaction chamber. Gas, 38sccm gallium source, 195sccm aluminum source and 19sccm magnesium source, grow a p-type AlGaN layer with a thickness of 100nm to 220nm, and then keep the reaction chamber temperature at 880°C for 10min to activate carriers. Among them, Mg doping can be performed in the growing p-type AlGaN layer, and the Mg doping concentration is 1×10 ¹⁹ cm ^-3 .

Step 7, using an inductively coupled plasma etching process to etch part of the p-type AlGaN layer to the n-type AlGaN layer to form an n-type AlGaN mesa, and using the method of sputtering metal to deposit n-type electrodes on the n-type AlGaN mesa, respectively, A p-type electrode is deposited on another part of the p-type AlGaN layer to complete the preparation of the light-emitting diode.

Specifically, in this embodiment, the inductively coupled plasma etching method is used to partially etch the p-type AlGaN layer from the top, and etch to the n-type AlGaN layer to form an n-type AlGaN mesa, and the n-type AlGaN mesa and the unetched Electrodes are respectively deposited on the p-type AlGaN layer, and the n-type electrode is deposited on the n-type AlGaN mesa by the method of sputtering metal, and the p-type electrode is deposited on the p-type AlGaN layer to complete the large-angle chamfered AlN sapphire substrate Fabrication of light-emitting diodes on epitaxial layer templates.

It should be noted that the AlN epitaxial layer of the large-angle chamfered sapphire substrate prepared in step 1 of this embodiment is not limited to being prepared by a PVD device, for example, it can also be prepared by a similar process using the MOCVD device in this embodiment.

The effect of the light-emitting diode manufacturing method proposed in this embodiment can be further illustrated by the following test results:

1. Test conditions:

The 800nm AlN epitaxial layer on the sapphire substrate with the c-plane deviated from the a-plane by 4° was selected at room temperature of 25°C in a nitrogen atmosphere.

2. Test content:

Test 1. Please refer to FIG. 6. FIG. 6 is the test result of the rocking curve of the X-ray diffraction (002) plane of the n-type AlGaN layer regrown on the high temperature annealed AlN layer in the method for preparing a light-emitting diode provided by the embodiment of the present invention. Compared with the schematic diagram, the abscissa in Fig. 6 is the Omega angle and the unit is arcsec, and the ordinate in Fig. 6 is the peak intensity after normalization processing. In this embodiment, the X-ray diffraction (002) plane rocking curve of the n-type AlGaN layer is tested, It can be observed from FIG. 6 that the (002) plane rocking curve half width of the n-type AlGaN thin film prepared by the preparation method of this embodiment is only 124 arcsec, which is much lower than 809 arcsec prepared by the traditional MOCVD method. The crystal quality was significantly improved, and the screw dislocation density was significantly reduced.

Test 2. Please refer to FIG. 7. FIG. 7 is the test result of the rocking curve of the X-ray diffraction (102) plane of the n-type AlGaN layer regrown on the high temperature annealed AlN layer in the method for preparing a light-emitting diode provided by the embodiment of the present invention Compared with the schematic diagram, the abscissa in Fig. 7 is the Omega angle and the unit is arcsec, and the ordinate in Fig. 7 is the peak intensity after normalization processing. In this embodiment, the X-ray diffraction (102) plane rocking curve of the n-type AlGaN layer is tested, It can be observed from FIG. 7 that the rocking curve half width of the (102) plane of the n-type AlGaN thin film prepared by the preparation method of this embodiment is only 598 arcsec, which is much lower than 1825 arcsec prepared by the traditional MOCVD method. The crystal quality is significantly improved, and the edge dislocation density is significantly reduced.

To sum up, the method for preparing a light-emitting diode provided in this embodiment has good compatibility with the existing MOCVD process for preparing AlGaN-based LEDs, and supports the use of technologies. The large-angle chamfered sapphire substrate prepared by the method in the first embodiment /AlN template, which can be used as a substrate to grow an AlGaN light-emitting layer. The AlGaN light-emitting layer emits deep ultraviolet light under the action of a current, which can significantly improve the quality of Al-component AlGaN materials and significantly improve the internal quantum efficiency of LEDs in the deep ultraviolet band. , which overcomes the problem that the development of deep ultraviolet devices on large-angle beveled sapphire substrates is limited.

The method for fabricating a light emitting diode provided in this embodiment can implement the method for fabricating AlN on a large-angle chamfered sapphire substrate described in Embodiment 1 above.

Embodiment 3

On the basis of the second embodiment above, please refer to FIG. 8 , which is a schematic structural diagram of a light emitting diode according to an embodiment of the present invention. This embodiment provides a light-emitting diode, the structure of which includes from bottom to top: a large-angle chamfered sapphire substrate AlN epitaxial layer 1, AlN homoepitaxial layer 2, n-type AlGaN layer 3, AlGaN/AlN The multiple quantum well layer 4, the AlGaN electron blocking layer 5, the p-type AlGaN layer 6 and the p-electrode 8, the n-type AlGaN layer 3 is provided with an n-electrode 7 above the side, and the light-emitting diode is prepared by using the light-emitting diode described in the second embodiment above The method is prepared and formed, wherein, the AlN epitaxial layer 1 of the large-angle chamfered sapphire substrate is prepared and formed by using the AlN preparation method of the large-angle chamfered sapphire substrate described in the first embodiment.

The light-emitting diode provided in this embodiment can implement the method for preparing AlN on a large-angle chamfered sapphire substrate described in the first embodiment and the method for preparing a light-emitting diode described in the second embodiment, and the implementation principles and technical effects are similar. , and will not be repeated here.

The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deductions or substitutions can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (10)

1. a large-angle chamfered sapphire substrate AlN preparation method, is characterized in that, comprises: Select a large angle to chamfer the sapphire substrate, a conventional sapphire substrate; growing an AlN layer on the large-angle chamfered sapphire substrate to obtain a large-angle chamfered sapphire substrate AlN epitaxial layer, and growing the AlN layer on the conventional sapphire substrate to obtain a conventional sapphire substrate AlN epitaxial layer; The AlN growth surface of the large-angle chamfered AlN epitaxial layer of the sapphire substrate is attached to the AlN growth surface of the conventional sapphire substrate AlN epitaxial layer, and placed in a high-temperature annealing furnace for high-temperature annealing. The high-angle chamfering of the AlN epitaxial layer on the sapphire substrate and the peeling of the AlN epitaxial layer on the conventional sapphire substrate; Repeatedly growing an AlN layer and high temperature annealing on the AlN epitaxial layer of the large-angle chamfered sapphire substrate after high-temperature annealing until the AlN layer on the AlN epitaxial layer of the large-angle chamfered sapphire substrate after the high-temperature annealing reaches a preset thickness , to complete the preparation of large-angle chamfered sapphire substrate AlN. 2. The method for preparing AlN of a large-angle bevel-cut sapphire substrate according to claim 1, wherein the bevel-cut direction of the large-angle bevel-cut sapphire substrate is that the c-plane deviates from the a-plane, and the bevel angle range is 0.2 °～6°. 3 . The method for preparing AlN of a large-angle chamfered sapphire substrate according to claim 1 , wherein the thickness of the AlN layer grown on the large-angle chamfered sapphire substrate is 200 nm to 400 nm. 4 . 4 . The method for preparing AlN of a large-angle chamfered sapphire substrate according to claim 1 , wherein the thickness of the AlN layer grown on the conventional sapphire substrate is 200 nm to 300 nm. 5 . 5. The preparation method of large-angle beveled sapphire substrate AlN according to claim 1, wherein the AlN growth plane of the large-angle beveled sapphire substrate AlN epitaxial layer and the conventional sapphire substrate AlN epitaxy The AlN growth surface of the layer is attached and placed in a high temperature annealing furnace for high temperature annealing including: The AlN growth surface of the AlN epitaxial layer of the AlN epitaxial layer of the sapphire substrate with the large angle beveled and the AlN growth surface of the AlN epitaxial layer of the conventional sapphire substrate are attached up and down, and placed in a high temperature annealing furnace, wherein the large angle oblique The AlN growth surface of the AlN epitaxial layer of the cut sapphire substrate is on the bottom, and the AlN growth surface of the AlN epitaxial layer on the conventional sapphire substrate is on the top. Process conditions: nitrogen and argon are introduced into the high-temperature annealing furnace, and nitrogen and argon are introduced into the annealing furnace. The gas volume ratio is 3:1, and the pressure in the high-temperature annealing furnace is maintained at 0.03 to 0.6 atmospheres; the temperature of the high-temperature annealing furnace is raised to 1600 ° C to 1750 ° C, and the high temperature annealing treatment is carried out for 1 h to 3 hours; Cool to room temperature. 6 . The method for preparing AlN of a large-angle chamfered sapphire substrate according to claim 5 , wherein the time for rapidly cooling the high-temperature annealing furnace to room temperature is controlled within 0.5h to 1.5h. 7 . 7 . The method for preparing AlN of a large-angle chamfered sapphire substrate according to claim 1 , wherein the preset thickness of the AlN layer of the AlN epitaxial layer of the large-angle chamfered sapphire substrate is 0.2 μm to 5 μm. 8 . 8. A method for preparing a light-emitting diode, comprising: A large-angle chamfered sapphire substrate AlN epitaxial layer is prepared by the method for preparing AlN of a large-angle chamfered sapphire substrate according to any one of claims 1 to 7, and the thickness of the AlN layer of the large-angle chamfered sapphire substrate AlN epitaxial layer is is the preset thickness; growing an AlN homoepitaxial layer on the AlN growth surface of the AlN epitaxial layer of the large-angle chamfered sapphire substrate; growing an n-type AlGaN layer on the AlN homoepitaxial layer; growing an AlGaN/AlN multiple quantum well layer on the n-type AlGaN layer; growing an AlGaN electron blocking layer on the AlGaN/AlN multiple quantum well layer; growing a p-type AlGaN layer on the AlGaN electron blocking layer; Part of the p-type AlGaN layer is etched to the n-type AlGaN layer by an inductively coupled plasma etching process to form an n-type AlGaN mesa, and a metal sputtering method is used to deposit n-type electrodes on the n-type AlGaN mesa, respectively, A p-type electrode is deposited on another part of the p-type AlGaN layer to complete the preparation of the light-emitting diode. 9 . The method for manufacturing a light emitting diode according to claim 8 , wherein the chamfering direction of the large-angle chamfered sapphire substrate is that the c-plane deviates from the a-plane, and the chamfering angle ranges from 0.2° to 6°. 10 . 10 . A light-emitting diode, characterized in that, the light-emitting diode is prepared by the preparation method of any one of claims 8 to 9 .

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