Luminescent layer structure, composite insertion layer structure, preparation method and application thereof

Abstract

The present invention discloses a light-emitting layer structure, a composite insertion layer structure, and its preparation method and application. The composite insertion layer structure includes: at least one composite insertion layer unit, comprising a first AlN layer, a first SiN layer, a second AlN layer, and a second SiN layer stacked sequentially along a selected direction, wherein the stacked structure formed by the first AlN layer, the first SiN layer, and the second AlN layer has multiple AlN microstructures and multiple SiN microstructures interlaced within the structure. The present invention reduces stress in the light-emitting layer of an epitaxial wafer, enhances the radiative recombination efficiency within the light-emitting layer, and improves the brightness of the LED epitaxial wafer.

Description

Technical Field

[0001] The present invention particularly relates to a light-emitting layer structure, a composite insertion layer structure, a preparation method and application thereof, and belongs to the technical field of semiconductor devices. Background Art

[0002] Nitride light-emitting diodes (LEDs) are semiconductor light-emitting devices with the advantages of long life, low energy consumption, small size, and high reliability. They play an increasingly important role in large-screen color displays, traffic lights, and lighting. However, they still have problems with low luminous intensity and efficiency. Further improving the luminous intensity and efficiency of LEDs is a goal that is constantly pursued in the development of LED lighting display application technology.

[0003] The LED production process generally involves three stages: epitaxial growth, chip manufacturing, and packaging. Epitaxial growth accounts for over 80% of the LED's brightness and is the core of the entire industry chain. Currently, due to the lack of GaN single crystals in nature and the extreme difficulty of growing bulk single crystal GaN, GaN material is primarily grown using heteroepitaxial methods. However, due to the significant lattice constant mismatch and thermal expansion coefficient differences between the substrate material and the III-V nitride semiconductor material, epitaxial growth of high-quality nitride materials is extremely difficult. This also leads to polarization effects in the nitride light-emitting layer, resulting in spatial separation of electrons and holes, reducing the overlap of electron and hole wave functions in the active region and the probability of radiative recombination, thereby reducing LED brightness and causing a "droop" effect in efficiency. Summary of the Invention

[0004] The main purpose of the present invention is to provide a light-emitting layer structure, a composite insertion layer structure, and a preparation method and application thereof, thereby overcoming the deficiencies in the prior art.

[0005] To achieve the aforementioned object of the invention, the technical solutions adopted by the present invention include:

[0006] A first aspect of the present invention provides a composite insertion layer structure, comprising at least one composite insertion layer unit, wherein the composite insertion layer unit comprises a first AlN layer, a first SiN layer, a second AlN layer, and a second SiN layer stacked in sequence along a selected direction, wherein the interior of the stacked structure layer formed by the first AlN layer, the first SiN layer, and the second AlN layer has a plurality of AlN microstructures and a plurality of SiN microstructures that are intertwined and distributed.

[0007] A second aspect of the present invention provides a method for preparing a composite insert layer structure, comprising:

[0008] The step of preparing a precursor for forming a composite insert structure, the precursor comprising a first Al layer, a Si layer, and a second Al layer stacked in a selected direction;

[0009] The precursor is heat-treated under at least the condition that a Si source and a N source coexist, so that at least part of the Al atoms in the first Al layer and the second Al layer and part of the Si atoms in the Si layer are mutually dissolved and diffused, and at least part of the Al atoms and at least part of the Si atoms in the precursor are respectively combined with the N atoms provided by the N source to form AlN and SiN, and part of the Si atoms in the Si source are also combined with part of the N atoms in the N source to form SiN, thereby forming a composite insertion layer unit.

[0010] The third aspect of the present invention provides a light-emitting layer structure, which includes at least one quantum well layer and at least one quantum barrier layer stacked in sequence along a selected direction, the quantum barrier layer includes at least two barrier layers stacked along the selected direction and at least one composite insertion layer, wherein at least one composite insertion layer is arranged between two adjacent barrier layers, and the composite insertion layer includes the composite insertion layer structure.

[0011] A fourth aspect of the present invention provides an epitaxial wafer comprising the light-emitting layer structure.

[0012] A fifth aspect of the present invention provides a light-emitting device comprising the epitaxial wafer.

[0013] Compared with the prior art, the present invention reduces the stress of the light-emitting layer in the epitaxial wafer, enhances the radiation recombination efficiency in the light-emitting layer, and improves the brightness of the LED epitaxial wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic structural diagram of an LED epitaxial wafer provided in a typical embodiment of the present invention;

[0015] Figure 2 1 is a schematic structural diagram of a composite insert layer provided in a typical embodiment of the present invention;

[0016] Figure 3 This is an electron microscope image of a partial structure of a composite insertion layer provided in a typical embodiment of the present invention;

[0017] Figure 4 This is a schematic diagram of a process for preparing an LED epitaxial wafer provided in a typical embodiment of the present invention;

[0018] Figure 5 This is a schematic diagram of a preparation process of a composite insert layer provided in a typical embodiment of the present invention;

[0019] Figure 6 Schematic diagram of the structure of the composite insertion layer used in Comparative Example 1. DETAILED DESCRIPTION

[0020] In view of the shortcomings of the prior art, the inventors of this case, after long-term research and extensive practice, have proposed the technical solution of the present invention. The following will further explain this technical solution, its implementation process and principles.

[0021] A first aspect of the present invention provides a composite insertion layer structure, comprising at least one composite insertion layer unit, wherein the composite insertion layer unit comprises a first AlN layer, a first SiN layer, a second AlN layer, and a second SiN layer stacked in sequence along a selected direction, wherein the interior of the stacked structure layer formed by the first AlN layer, the first SiN layer, and the second AlN layer has a plurality of AlN microstructures and a plurality of SiN microstructures that are intertwined and distributed.

[0022] Furthermore, the plurality of AlN microstructures include a plurality of first AlN microstructures and a plurality of second AlN microstructures, and the plurality of first AlN microstructures and the plurality of second AlN microstructures are spaced apart and distributed in the first SiN layer.

[0023] Furthermore, the plurality of SiN microstructures include a plurality of first SiN microstructures and a plurality of second SiN microstructures, the plurality of first SiN microstructures are distributed at intervals in the first AlN layer, and the plurality of second SiN microstructures are distributed at intervals in the second AlN layer.

[0024] Furthermore, the plurality of first AlN microstructures are integrated with the first AlN layer, and the plurality of second AlN microstructures are integrated with the second AlN layer.

[0025] Furthermore, the plurality of first SiN microstructures and the plurality of second SiN microstructures are integrated with the first SiN layer.

[0026] Furthermore, the second SiN layer has a plurality of nanopore structures therein.

[0027] Furthermore, the nanopore structure is a through-hole within a through-hole that penetrates the second SiN layer along the selected direction.

[0028] Furthermore, the nanopore structure is formed by the discontinuous membrane structure of the second SiN layer itself.

[0029] In a more typical embodiment, the composite insert layer structure includes: a plurality of the composite insert layer units, and the plurality of the composite insert layer units are stacked in sequence along the selected direction.

[0030] A second aspect of the present invention provides a method for preparing a composite insert layer structure, comprising:

[0031] The step of preparing a precursor for forming a composite insert structure, the precursor comprising a first Al layer, a Si layer, and a second Al layer stacked in a selected direction;

[0032] The precursor is heat-treated under at least the condition that a Si source and a N source coexist, so that at least part of the Al atoms in the first Al layer and the second Al layer and part of the Si atoms in the Si layer are mutually dissolved and diffused, and at least part of the Al atoms and at least part of the Si atoms in the precursor are respectively combined with the N atoms provided by the N source to form AlN and SiN, and part of the Si atoms in the Si source are also combined with part of the N atoms in the N source to form SiN, thereby forming a composite insertion layer unit.

[0033] Furthermore, the composite insertion layer unit includes a first AlN layer, a first SiN layer, a second AlN layer, and a second SiN layer sequentially stacked along a selected direction, wherein the stacked structure layer formed by the first AlN layer, the first SiN layer, and the second AlN layer has a plurality of AlN microstructures and a plurality of SiN microstructures distributed in an interlaced manner, and the second SiN layer has a plurality of nanopore structures therein;

[0034] The first AlN layer is formed by combining a portion of Al atoms in the first Al layer with N atoms provided by the N source, the second AlN layer is formed by combining a portion of Al atoms in the second Al layer with N atoms provided by the N source, the first SiN layer is formed by combining a portion of Si in the Si layer with N atoms provided by the N source, a plurality of AlN microstructures are formed by combining a portion of Al atoms diffused from the first Al layer or the second Al layer into the Si layer or the first SiN layer with N atoms provided by the N source, and a plurality of SiN microstructures are formed by combining a portion of Si atoms diffused from the Si layer into the first Al layer / the first AlN layer, the second Al layer / the second AlN layer with N atoms provided by the N source.

[0035] Furthermore, the plurality of AlN microstructures include a plurality of first AlN microstructures and a plurality of second AlN microstructures, and the plurality of first AlN microstructures and the plurality of second AlN microstructures are spaced apart and distributed in the first SiN layer. The first AlN microstructure is formed by combining a portion of Al atoms diffused from the first Al layer into the Si layer or the first SiN layer with N atoms provided by the N source, and the second AlN microstructure is formed by combining a portion of Al atoms diffused from the second Al layer into the Si layer or the first SiN layer with N atoms provided by the N source.

[0036] Furthermore, the multiple SiN microstructures include multiple first SiN microstructures and multiple second SiN microstructures, the multiple first SiN microstructures are spaced apart in the first AlN layer, and the multiple second SiN microstructures are spaced apart in the second AlN layer. The first SiN microstructures are formed by combining a portion of Si atoms diffused from the Si layer into the first Al layer / the first AlN layer with N atoms provided by the N source, and the second SiN microstructures are formed by combining a portion of Si atoms diffused from the Si layer into the second Al layer / the second AlN layer with N atoms provided by the N source.

[0037] Furthermore, the plurality of first AlN microstructures are integrated with the first AlN layer, and the plurality of second AlN microstructures are integrated with the second AlN layer.

[0038] Furthermore, the plurality of first SiN microstructures and the plurality of second SiN microstructures are integrated with the first SiN layer.

[0039] Furthermore, the heat treatment temperature is 900° C. to 1200° C., and the pressure is 100 torr to 500 torr.

[0040] Furthermore, when the precursor is heat-treated, the supply flow rate of the Si source is 10 scc-300 sccm, and the supply flow rate of the N source is 2 slm-50 slm.

[0041] Furthermore, the heat treatment time is 15s~45s.

[0042] Furthermore, the second SiN layer has a plurality of nanopore structures therein.

[0043] Furthermore, the nanopore structure is a through-hole within a through-hole that penetrates the second SiN layer along the selected direction.

[0044] Furthermore, the nanopore structure is formed by the discontinuous membrane structure of the second SiN layer itself.

[0045] The third aspect of the present invention provides a light-emitting layer structure, which includes at least one quantum well layer and at least one quantum barrier layer stacked in sequence along a selected direction, the quantum barrier layer includes at least two barrier layers stacked along the selected direction and at least one composite insertion layer, wherein at least one composite insertion layer is arranged between two adjacent barrier layers, and the composite insertion layer includes the composite insertion layer structure.

[0046] Furthermore, the quantum barrier layer includes a first barrier layer, a second barrier layer, and a third barrier layer stacked along the selected direction, and the composite insertion layer is stacked between the second barrier layer and at least one of the first barrier layer and the third barrier layer.

[0047] Furthermore, the quantum well layer and the quantum barrier layer are periodically and repeatedly stacked.

[0048] Furthermore, the quantum well layer and the quantum barrier layer are both made of nitride.

[0049] Furthermore, the materials of the quantum well layer and the quantum barrier layer are both group III-V nitrides.

[0050] Furthermore, the material of the quantum barrier layers is nitride containing Al.

[0051] A fourth aspect of the present invention provides an epitaxial wafer comprising the light-emitting layer structure.

[0052] A fifth aspect of the present invention provides a light-emitting device comprising the epitaxial wafer.

[0053] The technical solution, its implementation process and principles will be further explained below in conjunction with the accompanying drawings and specific implementation cases. Unless otherwise specified, the semiconductor epitaxial growth, metal deposition, nitrogen heat treatment processes and equipment used in the embodiments of the present invention are well known to those skilled in the art and are not specifically limited or described here.

[0054] In a typical implementation case, please refer to Figure 1 An LED epitaxial wafer includes a substrate and a first nitride layer, a nitride light-emitting layer, and a second nitride layer sequentially stacked on the substrate along a selected direction. The nitride light-emitting layer includes a nitride quantum well layer, a first nitride barrier layer, a composite insertion layer, a second nitride barrier layer, and a third nitride barrier layer sequentially stacked on the first nitride layer along a selected direction. The second nitride layer is stacked on the third nitride barrier layer. It should be noted that Figure 1 Only the case where a composite insertion layer is set between the first nitride barrier layer and the second nitride barrier layer is shown. Of course, the composite insertion layer can also be set between the second nitride barrier layer and the third nitride barrier layer, or a composite insertion layer can be set between the first nitride barrier layer and the second nitride barrier layer and between the second nitride barrier layer and the third nitride barrier layer.

[0055] Specifically, the first nitride layer is an n-type doped nitride layer, and the doping concentration of the n-type impurities is 1×10 18 cm -3 ~1×10 19 cm -3More specifically, the material of the first nitride layer is a III-V group nitride. For example, the first nitride layer can be an n-type GaN layer, an n-type AlGaN layer, or an n-type InGaN layer. Specifically, the second nitride layer is a p-type doped nitride layer, and the p-type impurity doping concentration is 1×10 19 cm -3 ~1×10 21 cm -3 More specifically, the second nitride layer is made of a III-V group nitride. For example, the second nitride layer can be a p-type GaN layer, a p-type AlGaN layer, or a p-type InGaN layer.

[0056] Specifically, the material of the nitride quantum well layer is a group III-V nitride. Exemplarily, the nitride quantum well layer can be a GaN quantum well layer, an AlGaN quantum well layer, or an InGaN quantum well layer.

[0057] Specifically, the material of the first nitride barrier layer is a III-V nitride. Exemplarily, the first nitride barrier layer can be a GaN barrier layer, an AlGaN barrier layer, or an InGaN barrier layer. Specifically, the second nitride barrier layer is mainly used to reduce the resistance of the nitride light-emitting layer, thereby reducing the operating voltage of the epitaxial wafer. Specifically, the material of the second nitride barrier layer is a III-V nitride. Exemplarily, the second nitride barrier layer can be a GaN barrier layer, an AlGaN barrier layer, or an InGaN barrier layer, with a doping concentration of 2×10 17 cm -3 ~8×10 17 cm -3 Specifically, the third nitride barrier layer is made of a III-V group nitride. Exemplarily, the third nitride barrier layer may be a GaN barrier layer, an AlGaN barrier layer, or an InGaN barrier layer.

[0058] Please also refer to Figure 2 and Figure 3 , the composite insert layer comprises at least one composite insert layer unit, Figure 2 The structure of a single composite insertion layer unit is shown, each of the composite insertion layer units includes a first AlN layer, a first SiN layer, a second AlN layer, and a second SiN layer stacked in sequence along a selected direction, wherein the interior of the stacked structure layer formed by the first AlN layer, the first SiN layer, and the second AlN layer has multiple AlN microstructures and multiple SiN microstructures that are intertwined and distributed.

[0059] Specifically, the plurality of AlN microstructures include a plurality of first AlN microstructures and a plurality of second AlN microstructures, and the plurality of first AlN microstructures and the plurality of second AlN microstructures are spaced apart and distributed in the first SiN layer; the plurality of SiN microstructures include a plurality of first SiN microstructures and a plurality of second SiN microstructures, and the plurality of first SiN microstructures are spaced apart and distributed in the first AlN layer, and the plurality of second SiN microstructures are spaced apart and distributed in the second AlN layer.

[0060] More specifically, the plurality of first AlN microstructures are integrated with the first AlN layer, the plurality of second AlN microstructures are integrated with the second AlN layer, and the plurality of first SiN microstructures and the plurality of second SiN microstructures are integrated with the first SiN layer.

[0061] On the one hand, the composite insertion layer in the present invention can effectively release the stress in the composite insertion layer through relaxation between the internal AlN and SiN polycrystalline interface, improve the crystal quality of the AlN layer / AlN microstructure, reduce the scattering of light by defects, and greatly improve the brightness and leakage performance of the epitaxial wafer; on the other hand, the composite insertion layer in the present invention increases the longitudinal extension distance of Si atoms with small atomic radius in the thickness direction, and the introduction of Si atoms can be used to modulate the lattice constant of the Al-containing nitride quantum barrier layer, further introduce tensile stress in the nitride quantum barrier layer, and better compensate for the compressive stress of the nitride quantum well layer, reduce the internal stress distribution of the nitride quantum well layer, improve the crystal quality and composition uniformity of the nitride quantum well layer, and reduce non-radiative recombination. Furthermore, the surface of the composite insertion layer introduced by the present invention has a surface with a low N vacancy concentration distribution, which reduces the capture of holes, improves the uniformity of carrier distribution in the nitride light-emitting layer, improves the radiative recombination efficiency, and improves the brightness of the epitaxial wafer.

[0062] More specifically, the second SiN layer comprises multiple nanopore structures. Specifically, the nanopore structures are through-holes extending through the second SiN layer along the selected direction. More specifically, the nanopore structures are formed by discontinuous membrane structures within the second SiN layer itself. Nanopores often nucleate at dislocation centers, shielding dislocations on the surface of the composite insertion layer and preventing them from extending upward to form leakage paths. The N heat treatment also fills N vacancies, reducing nitrogen vacancy defects on the surface of the composite insertion layer and improving leakage performance of the epitaxial wafer.

[0063] In a more specific embodiment, please refer to Figure 4 A method for preparing an LED epitaxial wafer comprises the following steps:

[0064] (1) Providing a substrate for growing an LED epitaxial wafer. The substrate may be a Si substrate, a GaN substrate, or a sapphire substrate.

[0065] (2) Growing a first nitride layer with a thickness of 1 μm to 10 μm on the substrate at a temperature of 1050° C. to 1150° C. and a pressure of 100 torr to 500 torr.

[0066] Specifically, the first nitride layer is an n-type doped nitride layer, and the doping concentration of the n-type impurities is 1×10 18 cm -3 ~1×10 19 cm -3 More specifically, the first nitride layer is made of a III-V group nitride. For example, the first nitride layer can be an n-type GaN layer, an n-type AlGaN layer, or an n-type InGaN layer.

[0067] (3) Growing a nitride light-emitting layer on the first nitride layer, specifically comprising:

[0068] S31: growing a nitride quantum well layer with a thickness of 1 nm to 8 nm on the first nitride layer at a temperature of 700° C. to 1000° C. and a pressure of 100 torr to 500 torr.

[0069] Specifically, the material of the nitride quantum well layer is a group III-V nitride. Exemplarily, the nitride quantum well layer can be a GaN quantum well layer, an AlGaN quantum well layer, or an InGaN quantum well layer.

[0070] S32: Growing a first nitride barrier layer (i.e., the aforementioned first barrier layer) with a thickness of 1 nm to 3 nm on the nitride quantum well layer at a temperature of 750° C. to 1050° C. and a pressure of 100 torr to 500 torr. The first nitride barrier layer serves as a contact layer for the nitride quantum well layer and also as a growth template for the composite insertion layer.

[0071] Specifically, the material of the first nitride barrier layer is a group III-V nitride. Exemplarily, the first nitride barrier layer can be a GaN barrier layer, an AlGaN barrier layer, or an InGaN barrier layer.

[0072] S33: Please also refer to Figure 5 Growing a composite insertion layer on the first nitride barrier layer comprises at least the following steps:

[0073] S331: Under the conditions of temperature of 500℃~1000℃, pressure of 200torr~300torr and reducing atmosphere, an Al source is introduced into the reaction chamber at a flow rate of 100sccm~300sccm, and maintained for 2s~10s to form a first Al deposition layer (i.e. the aforementioned first Al layer, the same below) on the first nitride barrier layer.

[0074] Specifically, the first deposited Al layer can play a blocking role when performing step S332, preventing Si atoms from crossing the first nitride barrier layer and entering the nitride quantum well layer, thereby avoiding the non-radiative recombination in the nitride quantum well layer, reduced brightness of the epitaxial wafer, and leakage problems caused thereby.

[0075] S332: In a reducing gas atmosphere at a temperature of 500°C to 1000°C and a pressure of 200 torr to 300 torr, a Si source is introduced into the reaction chamber at a flow rate of 10 sccm to 300 sccm. The heat treatment is performed for 5s to 20s to form a Si deposition layer (i.e., the aforementioned Si layer, the same below) on the first Al deposition layer.

[0076] S333: Under the conditions of temperature of 500℃~1000℃, pressure of 100torr~200torr and reducing atmosphere, an Al source is introduced into the reaction chamber at a flow rate of 10sccm~100sccm, and heat treatment is performed for 5s~15s to form a second Al deposition layer (i.e. the aforementioned second Al layer, the same below) on the Si deposition layer, thereby forming a precursor of the composite insertion layer.

[0077] Specifically, the second Al deposition layer acts as a covering layer, which is used to block the Si atom enrichment in the Si deposition layer, and prevent the enriched Si from acting as a carrier scattering center to cause carrier scattering during the transmission process in the nitride light-emitting layer, thereby reducing the carrier transmission ability in the nitride light-emitting layer, and ultimately causing uneven distribution of carriers in the nitride light-emitting layer, affecting the luminescence performance.

[0078] S334: Under the conditions of a temperature of 900°C to 1200°C, a pressure of 100 torr to 500 torr and a reducing atmosphere, a Si source and a N source are continuously introduced into the reaction chamber, the Si source flow rate is 10 sccm to 300 sccm, and the N source flow rate is 2 slm to 50 slm, and the precursor of the composite insertion layer is heat-treated for 15s to 45s, thereby converting the precursor of the composite insertion layer into a composite insertion layer, such as Figure 2 and Figure 3 shown.

[0079] Specifically, during the N and Si co-heat treatment in step S334, Al atoms and Si atoms in the precursor of the composite insertion layer diffuse into each other. Under the N heat treatment, the first and second Al deposited layers and the diffused Al atoms form AlN, while the Si deposited layer and the diffused Si atoms form SiN, thereby forming an AlN / SiN stack having multiple AlN and SiN microstructures interlaced. Furthermore, a portion of the Si atoms in the Si source treatment in step S334 combine with a portion of the N atoms that did not participate in the nitrogen heat reaction of the first and second Al deposited layers and the Si deposited layer to form a nanometer-thick SiN layer (i.e., the aforementioned second SiN layer) distributed on the surface of the AlN / SiN stack. This SiN layer has multiple nanopore structures formed by discontinuities. The nanofilm layer often nucleates at dislocation centers, thus shielding dislocations on the surface of the composite insertion layer and preventing them from extending upward to form leakage channels. The N heat treatment also fills N vacancies, reducing nitrogen vacancy defects on the surface of the composite insertion layer and improving the leakage performance of the epitaxial wafer.

[0080] Specifically, the AlN / SiN stack includes a first AlN layer, a first SiN layer, and a second AlN layer stacked in sequence, as well as a plurality of AlN microstructures and a plurality of SiN microstructures, wherein the plurality of AlN microstructures include a plurality of first AlN microstructures and a plurality of second AlN microstructures, and the plurality of first AlN microstructures and the plurality of second AlN microstructures are spaced apart in the first SiN layer, and the plurality of SiN microstructures include a plurality of first SiN microstructures and a plurality of second SiN microstructures, and the plurality of first SiN microstructures are spaced apart in the first AlN layer, and the plurality of second SiN microstructures are spaced apart in the second AlN layer, wherein the first AlN layer is formed by converting a portion of the first Al deposited layer through N heat treatment, and the The first SiN layer is formed by transforming a portion of the Si deposited layer through N heat treatment, the second AlN layer is formed by transforming a portion of the second Al deposited layer through N heat treatment, the first AlN microstructure is formed by transforming a portion of Al atoms diffused from the first Al deposited layer into the Si deposited layer through N heat treatment, the second AlN microstructure is formed by transforming a portion of Al atoms diffused from the second Al deposited layer into the Si deposited layer through N heat treatment, the first SiN microstructure is formed by transforming a portion of Si atoms diffused from the Si deposited layer into the first Al deposited layer through N heat treatment, and the second SiN microstructure is formed by transforming a portion of Si atoms diffused from the Si deposited layer into the second Al layer through N heat treatment.

[0081] S34: growing a second nitride barrier layer (ie, the aforementioned second barrier layer) with a thickness of 3 nm to 9 nm on the composite insertion layer at a temperature of 750° C. to 1050° C. and a pressure of 100 torr to 500 torr.

[0082] Specifically, the second nitride barrier layer is mainly used to reduce the resistance of the nitride light-emitting layer, thereby reducing the operating voltage of the epitaxial wafer.

[0083] Specifically, the material of the second nitride barrier layer is a III-V group nitride. For example, the second nitride barrier layer can be a GaN barrier layer, an AlGaN barrier layer, or an InGaN barrier layer, etc., with a doping concentration of 2×10 17 cm -3 ~8×10 17 cm -3 ;

[0084] S35: growing a third nitride barrier layer (ie, the aforementioned third barrier layer) with a thickness of 3 nm to 9 nm on the second nitride barrier layer at a temperature of 750° C. to 1050° C. and a pressure of 100 torr to 500 torr.

[0085] Specifically, the material of the third nitride barrier layer is a III-V group nitride. Exemplarily, the third nitride barrier layer can be a GaN barrier layer, an AlGaN barrier layer, or an InGaN barrier layer, etc.

[0086] S36: Periodically repeat steps S31 to S36 for more than 0 times to form a nitride light-emitting layer. As a typical embodiment, steps S31 to S36 may be periodically repeated for 2 to 15 times to form a nitride light-emitting layer.

[0087] (4) Under the conditions of a temperature of 950°C to 1150°C and a pressure of 100 torr to 500 torr, a second nitride layer with a thickness of 20 nm to 300 nm is grown on the nitride light-emitting layer to form an LED epitaxial wafer.

[0088] Specifically, the second nitride layer is a p-type doped nitride layer, and the doping concentration of the p-type impurities is 1×10 19 cm -3 ~1×10 21 cm -3 More specifically, the second nitride layer is made of a III-V group nitride. For example, the second nitride layer can be a p-type GaN layer, a p-type AlGaN layer, or a p-type InGaN layer.

[0089] It should be noted that, in another embodiment of the present invention, step S33 of growing a composite insertion layer can be performed after growing the second nitride barrier layer and before growing the third nitride barrier layer. Of course, in another embodiment of the present invention, step S33 of growing a composite insertion layer can be performed after growing the first nitride barrier layer and before growing the second nitride barrier layer, as well as after growing the second nitride barrier layer and before growing the third nitride barrier layer.

[0090] On the one hand, the composite insertion layer in the present invention can effectively release the stress in the composite insertion layer through relaxation between the internal AlN and SiN polycrystalline interface, improve the crystal quality of the AlN layer / AlN microstructure, reduce the scattering of light by defects, and greatly improve the brightness and leakage performance of the epitaxial wafer; on the other hand, the composite insertion layer in the present invention increases the longitudinal extension distance of Si atoms with small atomic radius in the thickness direction, and the introduction of Si atoms can be used to modulate the lattice constant of the Al-containing nitride quantum barrier layer, further introduce tensile stress in the nitride quantum barrier layer, and better compensate for the compressive stress of the nitride quantum well layer, reduce the internal stress distribution of the nitride quantum well layer, improve the crystal quality and composition uniformity of the nitride quantum well layer, and reduce non-radiative recombination. Furthermore, the surface of the composite insertion layer introduced by the present invention has a surface with a low N vacancy concentration distribution, which reduces the capture of holes, improves the uniformity of carrier distribution in the nitride light-emitting layer, improves the radiative recombination efficiency, and improves the brightness of the epitaxial wafer.

[0091] Specifically, the process adopted in step S334 of preparing the composite insertion layer of the present invention reduces the N vacancy concentration. The SiN layer (second SiN layer) formed at the same time has a surface roughening effect on the second nitride barrier layer, forming a nitride barrier layer with a surface roughening structure. During the periodic cycle of the nitride light-emitting layer, the nitride quantum well layer also presents a surface roughening structure, which generally increases the light-emitting area of ​​the nitride light-emitting layer, which is beneficial to improving the brightness of the epitaxial wafer. Moreover, the composite insertion layer introduced in the present invention also greatly reduces the stress in the nitride light-emitting layer, provides support for the nitride light-emitting layer with a large light-emitting surface, and does not cause excessive stress due to the increase in the contact area between the nitride quantum barrier and the nitride quantum well layer.

[0092] Example 1

[0093] A method for preparing an LED epitaxial wafer comprises the following steps:

[0094] (1) Provide 6-inch sapphire substrate.

[0095] (2) Under the conditions of temperature of 1050℃ and pressure of 100 torr, a 3μm thick n-type GaN layer was grown on a sapphire substrate, and the n-type impurity doping concentration was 5×10 18 cm -3.

[0096] (3) Growing a nitride light-emitting layer on the n-type GaN layer, specifically including:

[0097] S31: growing an InGaN quantum well layer with a thickness of 5 nm on the n-type GaN layer under the conditions of a temperature of 800° C. and a pressure of 300 Torr.

[0098] S32: growing a first AlGaN barrier layer with a thickness of 2 nm on the InGaN quantum well layer under conditions of a temperature of 800° C. and a pressure of 200 Torr.

[0099] S33: Growing a composite insertion layer on the first AlGaN barrier layer, comprising at least the following steps:

[0100] S331: Under the conditions of temperature of 600°C, pressure of 250 torr and reducing atmosphere, an Al source is introduced into the reaction chamber at a flow rate of 150 sccm and maintained for 5 seconds to form a first Al deposition layer on the first nitride barrier layer.

[0101] S332: At a temperature of 600°C, a pressure of 250 torr and a reducing gas atmosphere, a Si source is introduced into the reaction chamber at a flow rate of 200 sccm. The heat treatment is performed for 10 seconds to form a Si deposition layer on the first Al deposition layer.

[0102] S333: Under the conditions of temperature of 600°C, pressure of 150 torr and reducing atmosphere, an Al source is introduced into the reaction chamber with an Al source flow rate of 30 sccm. Heat treatment is performed for 10 seconds to form a second Al deposition layer on the Si deposition layer, thereby forming a precursor of the composite insertion layer.

[0103] S334: Under the conditions of a temperature of 1000°C, a pressure of 300 torr and a reducing atmosphere, Si source and N source are continuously introduced into the reaction chamber. The flow rate of Si source is 100 sccm, and the flow rate of N source is 10 slm. The precursor of the composite insertion layer is heat-treated for 30 seconds, thereby converting the precursor of the composite insertion layer into a composite insertion layer.

[0104] S34: Under the conditions of temperature of 800℃ and pressure of 250torr, a second AlGaN barrier layer with a thickness of 5nm is grown on the composite insertion layer. The doping concentration of the second AlGaN barrier layer is 5×10 17 cm -3 ;

[0105] S35: growing a third AlGaN barrier layer with a thickness of 5 nm on the second AlGaN barrier layer under conditions of a temperature of 800° C. and a pressure of 250 Torr, thereby forming a light emitting layer.

[0106] (4) Under the conditions of temperature of 1000℃ and pressure of 300torr, a p-type GaN layer with a thickness of 50nm is grown on the light-emitting layer. The p-type impurity doping concentration of the p-type GaN layer is 5×10 19 cm -3 , thus forming an LED epitaxial wafer.

[0107] Example 2

[0108] A method for preparing an LED epitaxial wafer comprises the following steps:

[0109] (1) Provide 6-inch sapphire substrate.

[0110] (2) Under the conditions of temperature of 1050℃ and pressure of 100 torr, a 3μm thick n-type GaN layer was grown on a sapphire substrate, and the n-type impurity doping concentration was 5×10 18 cm -3 .

[0111] (3) Growing a nitride light-emitting layer on the n-type GaN layer, specifically including:

[0112] S31: growing an InGaN quantum well layer with a thickness of 5 nm on the n-type GaN layer under the conditions of a temperature of 800° C. and a pressure of 300 Torr.

[0113] S32: growing a first AlGaN barrier layer with a thickness of 2 nm on the InGaN quantum well layer under conditions of a temperature of 800° C. and a pressure of 200 Torr.

[0114] S33: Under the conditions of temperature of 800°C and pressure of 250 torr, a second AlGaN barrier layer with a thickness of 5 nm is grown on the first AlGaN barrier layer. The doping concentration of the second AlGaN barrier layer is 5×10 17 cm -3 ;

[0115] S34: Growing a composite insertion layer on the second AlGaN barrier layer, comprising at least the following steps:

[0116] S341: Under the conditions of temperature of 500°C, pressure of 200 torr and reducing atmosphere, an Al source is introduced into the reaction chamber with an Al source flow rate of 100 sccm and maintained for 5 seconds to form a first Al deposition layer on the first nitride barrier layer.

[0117] S342: At a temperature of 500°C, a pressure of 200 torr and a reducing gas atmosphere, a Si source is introduced into the reaction chamber at a flow rate of 10 sccm. The heat treatment is performed for 15 seconds to form a Si deposition layer on the first Al deposition layer.

[0118] S343: Under the conditions of temperature of 500°C, pressure of 100 torr and reducing atmosphere, an Al source is introduced into the reaction chamber with an Al source flow rate of 10 sccm. Heat treatment is performed for 10 seconds to form a second Al deposition layer on the Si deposition layer, thereby forming a precursor of the composite insertion layer.

[0119] S344: Under the conditions of a temperature of 900°C, a pressure of 100 torr and a reducing atmosphere, Si source and N source are continuously introduced into the reaction chamber. The flow rate of Si source is 50 sccm, and the flow rate of N source is 2 slm. The precursor of the composite insertion layer is heat-treated for 30 seconds, thereby converting the precursor of the composite insertion layer into a composite insertion layer.

[0120] S35: growing a third AlGaN barrier layer with a thickness of 5 nm on the composite insertion layer under the conditions of a temperature of 800° C. and a pressure of 250 Torr, thereby forming a light-emitting layer.

[0121] (4) Under the conditions of temperature of 1000℃ and pressure of 300torr, a p-type GaN layer with a thickness of 50nm is grown on the light-emitting layer. The p-type impurity doping concentration of the p-type GaN layer is 5×10 19 cm -3 , thus forming an LED epitaxial wafer.

[0122] Example 3

[0123] A method for preparing an LED epitaxial wafer comprises the following steps:

[0124] (1) Provide a GaN substrate.

[0125] (2) Under the conditions of temperature of 1050℃ and pressure of 100torr, a 3μm thick n-type GaN layer was grown on a GaN substrate, and the doping concentration of n-type impurities was 5×10 18 cm -3 .

[0126] (3) Growing a nitride light-emitting layer on the n-type GaN layer, specifically including:

[0127] S31: growing an InGaN quantum well layer with a thickness of 5 nm on the n-type GaN layer under the conditions of a temperature of 800° C. and a pressure of 300 Torr.

[0128] S32: growing a first AlGaN barrier layer with a thickness of 2 nm on the InGaN quantum well layer under conditions of a temperature of 800° C. and a pressure of 200 Torr.

[0129] S33: Growing a composite insertion layer on the first AlGaN barrier layer, comprising at least the following steps:

[0130] S331: Under the conditions of temperature of 1000°C, pressure of 300 torr and reducing atmosphere, an Al source is introduced into the reaction chamber with an Al source flow rate of 300 sccm and maintained for 2 seconds to form a first Al deposition layer on the first nitride barrier layer.

[0131] S332: At a temperature of 1000°C, a pressure of 300 torr and a reducing gas atmosphere, a Si source is introduced into the reaction chamber at a flow rate of 300 sccm. The heat treatment is performed for 5 seconds to form a Si deposition layer on the first Al deposition layer.

[0132] S333: Under the conditions of temperature of 1000°C, pressure of 100 torr and reducing atmosphere, an Al source is introduced into the reaction chamber with an Al source flow rate of 100 sccm. Heat treatment is performed for 5 seconds to form a second Al deposition layer on the Si deposition layer, thereby forming a precursor of the composite insertion layer.

[0133] S334: Under the conditions of a temperature of 1200°C, a pressure of 500 torr and a reducing atmosphere, Si source and N source are continuously introduced into the reaction chamber. The flow rate of Si source is 300 sccm, and the flow rate of N source is 50 slm. The precursor of the composite insertion layer is heat-treated for 40 seconds to transform the precursor into a composite insertion layer.

[0134] S34: Under the conditions of temperature of 800℃ and pressure of 250torr, a second AlGaN barrier layer with a thickness of 5nm is grown on the composite insertion layer. The doping concentration of the second AlGaN barrier layer is 5×10 17 cm -3 ;

[0135] S35: growing a third AlGaN barrier layer with a thickness of 5 nm on the second AlGaN barrier layer under conditions of a temperature of 800° C. and a pressure of 250 Torr.

[0136] S36: Periodically repeat steps S31 to S36 three times to form a nitride light-emitting layer.

[0137] (4) Under the conditions of temperature of 1000℃ and pressure of 300torr, a p-type GaN layer with a thickness of 50nm is grown on the light-emitting layer. The p-type impurity doping concentration of the p-type GaN layer is 5×10 19 cm -3 , thus forming an LED epitaxial wafer.

[0138] Comparative Example 1

[0139] A method for preparing an LED epitaxial wafer comprises the following steps:

[0140] (1) Provide a GaN substrate.

[0141] (2) Under the conditions of temperature of 1050℃ and pressure of 100torr, a 3μm thick n-type GaN layer was grown on a GaN substrate, and the doping concentration of n-type impurities was 5×10 18 cm -3 .

[0142] (3) Growing a nitride light-emitting layer on the n-type GaN layer, specifically including:

[0143] S31: growing an InGaN quantum well layer with a thickness of 5 nm on the n-type GaN layer under the conditions of a temperature of 800° C. and a pressure of 300 Torr.

[0144] S32: growing a first AlGaN barrier layer with a thickness of 2 nm on the InGaN quantum well layer under conditions of a temperature of 800° C. and a pressure of 200 Torr.

[0145] S33: growing a first AlN layer, a first SiN layer, a second AlN layer, and a second SiN layer on the first AlGaN barrier layer in sequence to form a composite insertion layer, such as Figure 6 shown.

[0146] S34: Under the conditions of temperature of 800℃ and pressure of 250torr, a second AlGaN barrier layer with a thickness of 5nm is grown on the composite insertion layer. The doping concentration of the second AlGaN barrier layer is 5×10 17 cm -3 ;

[0147] S35: growing a third AlGaN barrier layer with a thickness of 5 nm on the second AlGaN barrier layer under conditions of a temperature of 800° C. and a pressure of 250 Torr, thereby forming a light emitting layer.

[0148] (4) Under the conditions of temperature of 1000℃ and pressure of 300torr, a p-type GaN layer with a thickness of 50nm is grown on the light-emitting layer. The p-type impurity doping concentration of the p-type GaN layer is 5×10 19 cm -3 , thus forming an LED epitaxial wafer.

[0149] The epitaxial wafers with a wavelength of 460±0.5nm obtained in Examples 1-3 and Comparative Example 1 were subjected to photoluminescence test wavelength uniformity std and X-ray diffractometer (XRD) test (102) half-peak width test, and the same chip processing technology was used to process the nitride light-emitting layer obtained in Examples 1-3 and Comparative Example 1 to obtain Micro-LED chips with a size of 4mil*6mil. The brightness and leakage test results of the obtained Micro-LED chips were respectively performed, as shown in Table 1.

[0150] Table 1 Brightness and leakage test results of various Micro-LED chips

[0151] WLD / nm std / nm (102) / arcsec Brightness mW / 2mA Leakage yield / % Example 1 460.1 0.56 187 12.9 100 Example 2 460.3 0.61 191 12.6 99 Example 3 460.0 0.53 195 13.8 99 Comparative Example 1 460.1 1.52 225 9.7 94

[0152] It can be seen from Table 1 that, compared with the prior art, the present invention reduces the stress of the light-emitting layer in the epitaxial wafer, improves the crystal quality of the epitaxial wafer, enhances the radiation recombination efficiency in the light-emitting layer, improves the brightness of the LED epitaxial wafer, and improves the leakage performance of the epitaxial wafer.

[0153] It should be understood that the above embodiments are merely illustrative of the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent variations or modifications made in accordance with the spirit and substance of the present invention are intended to be encompassed within the scope of protection of the present invention.

Claims

1. A composite insertion layer structure, arranged in a light-emitting layer structure, characterized in that: include: At least one composite insertion layer unit, the composite insertion layer unit comprising a first AlN layer, a first SiN layer, a second AlN layer, and a second SiN layer stacked in sequence along a selected direction, wherein the interior of the stacked structure layer formed by the first AlN layer, the first SiN layer, and the second AlN layer comprises a plurality of AlN microstructures and a plurality of SiN microstructures that are interlaced and distributed, the plurality of AlN microstructures comprising a plurality of first AlN microstructures and a plurality of second AlN microstructures, the plurality of first AlN microstructures and the plurality of second AlN microstructures being distributed at intervals within the first SiN layer, the plurality of SiN microstructures comprising a plurality of first SiN microstructures and a plurality of second SiN microstructures, the plurality of first SiN microstructures being distributed at intervals within the first AlN layer, and the plurality of second SiN microstructures being distributed at intervals within the second AlN layer.

2. The composite insert layer structure according to claim 1, characterized in that: The plurality of first AlN microstructures are integral with the first AlN layer, and the plurality of second AlN microstructures are integral with the second AlN layer.

3. The composite insert layer structure according to claim 1, characterized in that: The plurality of first SiN microstructures and the plurality of second SiN microstructures are integral with the first SiN layer.

4. The composite insert layer structure according to claim 1, characterized in that: The second SiN layer also has a plurality of nanopore structures therein.

5. The composite insert layer structure according to claim 4, characterized in that: The nanopore structure is a through-hole within a through-hole that penetrates the second SiN layer along the selected direction.

6. The composite insert layer structure according to claim 4, characterized in that: The nanopore structure is formed by the discontinuous membrane structure of the second SiN layer itself.

7. The composite insert layer structure according to claim 1, characterized in that: include: A plurality of the composite insertion layer units are stacked in sequence along the selected direction.

8. A method for preparing a composite insertion layer structure, wherein the composite insertion layer structure is arranged in a light-emitting layer structure, characterized in that: The preparation method of the composite insert layer structure comprises: The step of preparing a precursor for forming a composite insert structure, the precursor comprising a first Al layer, a Si layer, and a second Al layer stacked in a selected direction; The precursor is heat-treated under at least the condition that a Si source and a N source coexist, so that at least part of the Al atoms in the first Al layer and the second Al layer and part of the Si atoms in the Si layer are mutually dissolved and diffused, and at least part of the Al atoms and at least part of the Si atoms in the precursor are respectively combined with the N atoms provided by the N source to form AlN and SiN, and part of the Si atoms in the Si source are also combined with part of the N atoms in the N source to form SiN, thereby forming a composite insertion layer unit.

9. The method for preparing the composite insert layer structure according to claim 8, characterized in that: The composite insertion layer unit includes a first AlN layer, a first SiN layer, a second AlN layer, and a second SiN layer sequentially stacked along a selected direction, wherein the stacked structure layer formed by the first AlN layer, the first SiN layer, and the second AlN layer has a plurality of AlN microstructures and a plurality of SiN microstructures interlaced and distributed therein; The first AlN layer is formed by combining a portion of Al atoms in the first Al layer with N atoms provided by the N source, the second AlN layer is formed by combining a portion of Al atoms in the second Al layer with N atoms provided by the N source, the first SiN layer is formed by combining a portion of Si in the Si layer with N atoms provided by the N source, a plurality of AlN microstructures are formed by combining a portion of Al atoms diffused from the first Al layer or the second Al layer into the Si layer or the first SiN layer with N atoms provided by the N source, and a plurality of SiN microstructures are formed by combining a portion of Si atoms diffused from the Si layer into the first Al layer / the first AlN layer, the second Al layer / the second AlN layer with N atoms provided by the N source.

10. The method for preparing the composite insert layer structure according to claim 9, characterized in that: The multiple AlN microstructures include multiple first AlN microstructures and multiple second AlN microstructures. The multiple first AlN microstructures and the multiple second AlN microstructures are spaced apart in the first SiN layer. The first AlN microstructures are formed by combining a portion of Al atoms diffused from the first Al layer into the Si layer or the first SiN layer with N atoms provided by the N source. The second AlN microstructures are formed by combining a portion of Al atoms diffused from the second Al layer into the Si layer or the first SiN layer with N atoms provided by the N source.

11. The method for preparing the composite insert layer structure according to claim 9, characterized in that: The multiple SiN microstructures include multiple first SiN microstructures and multiple second SiN microstructures. The multiple first SiN microstructures are spaced apart in the first AlN layer, and the multiple second SiN microstructures are spaced apart in the second AlN layer. The first SiN microstructures are formed by combining a portion of Si atoms diffused from the Si layer into the first Al layer / the first AlN layer with N atoms provided by the N source. The second SiN microstructures are formed by combining a portion of Si atoms diffused from the Si layer into the second Al layer / the second AlN layer with N atoms provided by the N source.

12. The method for preparing the composite insert layer structure according to claim 10, characterized in that: The plurality of first AlN microstructures are integral with the first AlN layer, and the plurality of second AlN microstructures are integral with the second AlN layer.

13. The method for preparing the composite insert layer structure according to claim 11, characterized in that: The plurality of first SiN microstructures and the plurality of second SiN microstructures are integral with the first SiN layer.

14. The method for preparing the composite insert layer structure according to claim 8, characterized in that: The heat treatment temperature is 900° C. to 1200° C., and the pressure is 100 torr to 500 torr.

15. The method for preparing the composite insert layer structure according to claim 8, characterized in that: When the precursor is heat-treated, the supply flow rate of the Si source is 10 sccm to 300 sccm, and the supply flow rate of the N source is 2 slm to 50 slm.

16. The method for preparing the composite insert layer structure according to claim 8, characterized in that: The heat treatment time is 15s~45s.

17. The method for preparing the composite insert layer structure according to claim 9, characterized in that: The second SiN layer has a plurality of nanopore structures therein.

18. The method for preparing the composite insert layer structure according to claim 17, characterized in that: The nanopore structure is a through-hole within a through-hole that penetrates the second SiN layer along the selected direction.

19. The method for preparing the composite insert layer structure according to claim 17, characterized in that: The nanopore structure is formed by the discontinuous membrane structure of the second SiN layer itself.

20. A light-emitting layer structure comprising at least one quantum well layer and at least one quantum barrier layer stacked in sequence along a selected direction, characterized in that: The quantum barrier layer includes at least two barrier layers stacked along the selected direction and at least one composite insertion layer, wherein at least one composite insertion layer is arranged between two adjacent barrier layers, and the composite insertion layer includes the composite insertion layer structure according to any one of claims 1 to 7.

21. The light-emitting layer structure according to claim 20, characterized in that: The quantum barrier layer includes a first barrier layer, a second barrier layer, and a third barrier layer stacked along the selected direction, and the composite insertion layer is stacked between the second barrier layer and at least one of the first barrier layer and the third barrier layer.

22. The light-emitting layer structure according to claim 21, characterized in that: The quantum well layer and the quantum barrier layer are periodically and repeatedly stacked.

23. The light-emitting layer structure according to claim 21, characterized in that: The materials of the quantum well layer and the quantum barrier layer are both nitride.

24. The light-emitting layer structure according to claim 23, characterized in that: The materials of the quantum well layer and the quantum barrier layer are both group III-V nitrides, wherein the material of the quantum barrier layer is nitride containing Al.

25. An epitaxial wafer, characterized in that: The light-emitting layer structure comprises the light-emitting layer structure according to any one of claims 20 to 24.

26. A light emitting device, characterized in that: Comprising the epitaxial wafer according to claim 25.

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