WO2022089181A1 - Gan-on-si epitaxial substrate having 2d material interlayer - Google Patents

Abstract

Disclosed is a GaN-on-Si epitaxial substrate having a 2D material interlayer; a 2D material ultra-thin interposer having a polycrystalline orientation is provided on a silicon wafer substrate, and the 2D material ultra-thin interposer has at least one top layer; a top lattice constant is highly matched to AlN, AlGaN, or GaN; a GaN monocrystalline epitaxial layer is grown on the top layer of the 2D material ultra-thin interposer by van der Waals epitaxial growth, or, an AlGaN or AlN nucleation enhancer layer is grown on the top layer of the 2D material ultra-thin interposer by van der Waals epitaxial growth, then the nucleation enhancer layer has a GaN monocrystalline epitaxial layer. The present invention effectively overcomes the quality problem of defective GaN layers caused by heterogeneous epitaxial lattice mismatch, alleviates the problem of thermal stress caused in part by the difference in coefficient of thermal expansion, and is beneficial for use in growing high-quality GaN epitaxial layers for the fabrication of GaN-based wide-bandgap photoelectric and semiconductor components.

Description

GaN-on-Si epitaxial substrate with 2D material interlayer technical field

The present invention relates to a gallium nitride on silicon GaN-on-Si epitaxial substrate with an intermediate layer of 2D material.

Background technique

In the manufacturing process of optoelectronic and semiconductor components, epitaxy has an important impact on the quality of products. The impact on quality includes component performance, yield, reliability and life. Usually, the material of the substrate hopes to minimize the defect density of the single crystal material, and the crystal structure, lattice constant (lattice constant), and coefficient of thermal expansion (CTE, coefficient of thermal expansion) match the epitaxial material to avoid as much as possible in the epitaxy process. affect crystal quality. In recent years, the third-generation semiconductor technology and market have developed rapidly with the demand for power and high-frequency semiconductor components. The basis for quality improvement depends on the supply of high-quality epitaxial substrates of silicon carbide and gallium nitride, the two main protagonists of the third-generation semiconductor materials. Unlike GaN-based LEDs, which mainly use sapphire substrates, according to the current technology, the most commonly used GaN substrates are GaN-on-Si and GaN-on-SiC. on-SiC) two substrates.

The main reason comes from the current cost and size constraints of the development of GaN single crystal technology. The melting points of both aluminum nitride and gallium nitride are above 2500 degrees Celsius and there is a problem of high vapor pressure. In other words, if you want to directly produce single crystal substrates of the above two materials by the method of melting crystal growth, not only the manufacturing cost If it is higher, it will generate more waste heat and cause inevitable pollution to the environment. For the vapor phase crystal growth part, the current GaN crystal growth method adopts the hydride vapor phase epitaxy (HVPE) method to produce single crystal gallium nitride substrates. Due to the limitations of production cost and yield conditions, the current mass production The technology reaches 4-inch substrates and the cost is extremely high. In fact, the defect density of the above-mentioned vapor phase method is still higher than that of other liquid phase crystallization processes, but it is limited by the slow growth rate of the remaining processes and the higher cost of mass production. Under the consideration of compromise, the mainstream of commercial transformation is still limited to the HVPE method. The literature points out that the vapor-phase GaN crystal growth rate is still possible to increase several times and maintain good crystallinity, but due to the deterioration of defect density, it has not been used as an orientation to reduce the cost of GaN substrates. As for the aluminum nitride crystal growth technology, physical vapor transport (PVT), one of the gas phase methods, is used to produce single crystal aluminum nitride substrates. Due to the limitations of production technology and yield, only two manufacturers in the world have Mass production capacity, the current mass production technology only reaches 2-inch substrates and the cost is extremely high, and the production capacity is all occupied by a few manufacturers and cannot be widely supplied to the market. Due to the chemical characteristics of aluminum nitride itself and the limitations of physical vapor transport method hardware components, the existence of carbon (C) and oxygen (O) impurities in the finished single crystal product is inevitable, which also affects the component characteristics to a certain extent.

Table 1

A similar situation also exists in the current silicon carbide (SiC) single crystal. Silicon carbide substrates are the current substrate materials for high-performance power semiconductors and high-end light-emitting diodes. Transport, PVT), high-quality large-size silicon carbide single crystal growth technology is difficult, high-end mass production technology is in the hands of a few manufacturers, and there is still a lot of room for improvement in the application cost. Gallium nitride on silicon carbide (GaN-on-SiC) is a high-quality GaN epitaxial substrate, but for the above reasons, large-scale substrates have problems such as high price, limited supply and technology in the hands of a few manufacturers; relatively In other words, due to the large size, low cost, high productivity and stable quality of silicon substrates, the development of gallium nitride (GaN-on-Si) substrates on silicon wafers is more commonly concerned by relevant manufacturers.

Two substrate technologies, GaN-on-Si and GaN-on-SiC, are both heterojunction epitaxy technologies in epitaxy process. Overcoming the lattice matching problem between different materials and the thermal stress problem caused by the different thermal expansion coefficients between the epitaxial layer and the substrate, the higher quality of GaN-on-SiC than GaN-on-Si is precisely because of the GaN-on-SiC lattice The degree of mismatch (lattice mismatch) is smaller than that of GaN-on-Si; another important feature is that the gallium nitride layer has significant tensile stress on the silicon surface. When the thickness of the gallium nitride layer is increased, the stress is higher, resulting in the bending of the substrate Deformation and even cracking of the gallium nitride layer is possible, and the associated effects become more severe as the wafer size increases. Relevant technical difficulties have led to the generally low yield of GaN-on-Si, and it is mostly used in power supply products. Currently, mass production is still dominated by six inches, and the advantages of large size of silicon wafers have not been fully utilized.

Two-dimensional (2D) materials is a rapidly developing emerging field. The earliest and most well-known material in the 2D material family that attracts a lot of R&D investment is graphene, whose two-dimensional layered structure has special or Excellent physical/chemical/mechanical/optical properties, there is no strong bond between layers, only van der Waals force, which also means that there is no dangling bond on the surface of the layered structure. At present, graphene has been It has been confirmed to have a wide range of excellent application potential; graphene research and development work is generally carried out around the world, and it also drives the research and development of more 2D materials, including hexagonal boron nitride hBN (hexagonal Boron Nitride), transition metal dichalcogenide TMDs (transition metal dichalcogenide TMDs (transition metal dichalcogenide) Metal dichalcogenides) and black phosphorus are also the ones who have accumulated more research and development achievements in the 2D material family. Each of the above materials has specific material properties and application potential, and the manufacturing technology development of related materials is also actively promoted. In addition to its excellent optoelectronic properties, graphene, hBN and MoS ₂ , one of the TMDs materials, are considered to have excellent diffusion barrier properties and varying degrees of high temperature stability. In particular, hBN has excellent chemical passivation properties. Inertness and high temperature oxidation resistance.

Due to the above-mentioned nature of the layered structure and the bonding characteristics of the van der Waals force between layers, the technical feasibility of fabricating two or more materials in the 2D material family into layered stacked hetero-structures (hetero-structures) is greatly opened. Different characteristics make it possible to create new application characteristics or make new components. At present, the research and development in the field of optoelectronics and semiconductors is quite active. Specifically, it can be mechanical composition lamination, or physical or chemical vapor deposition.

The van der Waals bonding characteristics of 2D materials have also attracted attention for the use of epitaxial substrates applied to traditional 3D materials. expansion) must be very well matched with the substrate material, but in reality, it often encounters situations such as the lack of suitable substrate materials for the subject of the present invention, or the ideal substrate material is expensive or difficult to obtain. Another solution, the so-called van der Waals Epitaxy. The mechanism that van der Waals epitaxy may be beneficial to heteroepitaxy comes from the fact that the direct chemical bonds at the traditional epitaxy interface are replaced by van der Waals force bonding, which will relieve the stress or strain energy from the mismatch of lattice and thermal expansion in the epitaxy process to a certain extent. , so that the quality of the epitaxial layer can be improved, or through the introduction of 2D materials and van der Waals epitaxy, some hetero-epitaxial technologies that could not be practical before become possible. Relevant studies also pointed out that when the above-mentioned 2D materials are stacked with each other in heterostructures, the interaction force is dominated by van der Waals forces; while the epitaxial time of 3D materials on 2D materials, due to the dangling bonds of 3D materials on the interface ( dangling bond) while contributing to the bonding force of the interface, this epitaxy is not essentially a pure van der Waals epitaxy (van der Waals Epitaxy) or more precisely Quasi van der Waals Epitaxy (Quasi van der Waals Epitaxy); in either case , the matching degree of lattice and thermal expansion undoubtedly still plays a certain role in the final epitaxy quality, and both the 2D material interposer and the substrate material contribute to the overall matching degree. The above-mentioned 2D layered material has a hexagon or honeycomb structure, and is considered to be structurally compatible with Wurtzite and Zinc-Blende structural materials in epitaxial time, and the related fields of the present invention are mainly Epitaxial materials belong to this type of structure.

Based on the use of epitaxial substrates, single crystal is one of the requirements to ensure the quality of epitaxial crystals. Generally, the growth of 2D materials tends to correlate with the crystal orientation of the crystalline substrate during the nucleation stage. It belongs to a polycrystalline structure, and the 2D material has already formed an inconsistent direction in the nucleation stage. After the nuclei aggregate into a continuous film with the growth, there are still domains with different orientations instead of single crystals; when the substrate is a single crystal material such as sapphire, it is still Due to the symmetry correlation between the two structures, the possible specific nucleation direction is not unique, and it is impossible to form a single crystal continuous film. Recent studies have found that by improving the existing process, when the copper foil is heat-treated to form a copper foil with a specific lattice orientation, the anisotropic lattice domains formed during the growth of 2D materials graphene and hexagonal boron nitride (hBN) can be eliminated. ) feature while growing into continuous thin films of single-crystal graphene and hexagonal boron nitride.

In recent years, many studies have pointed out that 2D material families are usually ideal substrate materials for heteroepitaxy. For example, hBN is regarded as an excellent epitaxial substrate for transition metal dichalcogenides (transition metal dichalcogenides) materials. The surface can be epitaxially grown with MoS ₂ , WS ₂ , MoSe ₂ , WSe ₂ and other TMD materials and maintain up to 95% of the surface area as a single crystal continuous film.

Recent studies have pointed out that layered MoS ₂ , WS ₂ , MoSe ₂ , WSe ₂ and other TMD materials with good crystallinity can be grown on the c-plane sapphire surface of a single crystal by CVD or other methods. There are two types of TMD materials grown. (0° and 60°) crystal orientation (reference: Nature 2019, v. 567, 169-170). For the AlGaN and GaN materials concerned by the present invention, the crystal structure has hexagonal symmetry on the epitaxial junction. Although the above-mentioned TMD layer does not constitute a single crystal layer, theoretically it does not hinder AlGaN and GaN epitaxy when used as an epitaxial substrate. The technology of peeling off the TMD layer from the sapphire surface and transferring it to the surface of other substrates has been practical and large-scale, and the sapphire substrate can be recycled and used repeatedly, which is a feasible process for commercial mass production (ref. : ACS Nano 2015, 9, 6, 6178-6187). Therefore, in addition to the previous method of fabricating TMD single-crystal continuous thin films, transferring the TMD layer on the sapphire surface to a substrate whose thermal expansion coefficient is highly matched to AlGaN and GaN is another feasible solution for mass production.

The existing process gallium nitride on silicon wafer (GaN-on-Si), as shown in Figure 1. Heteroepitaxy needs to overcome the lattice matching problem between different materials, as well as the thermal stress problem caused by the different thermal expansion coefficients between the epitaxial layer and the substrate. The GaN-on-Si lattice mismatch is relatively high, resulting in During the epitaxy process, the defect density of the gallium nitride layer is relatively high; another important feature is that the gallium nitride layer has significant tensile stress on the silicon surface. When the thickness of the gallium nitride layer is increased, the stress is higher, resulting in the bending deformation of the substrate or even nitriding The gallium layer may crack, and the associated effect becomes more severe as the wafer size increases. Relevant technical difficulties have led to the generally low yield of GaN-on-Si, and it is mostly used in power supply products. Currently, mass production is still dominated by six inches, and the advantages of large size of silicon wafers have not been fully utilized.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the prior art, the present invention provides a gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material intermediate layer.

The solution of the present invention is as follows:

A gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material intermediate layer, including a single crystal silicon wafer substrate;

A polycrystalline 2D material ultra-thin interposer on the silicon wafer substrate, and the polycrystalline 2D material ultra-thin interposer has at least one top layer;

The lattice constant of the top layer is highly matched with AlN, AlGaN or GaN; wherein, the lattice constant of the top layer is highly matched with GaN, and a GaN single crystal epitaxial layer is grown on the top layer of the 2D material ultra-thin interlayer by van der Waals epitaxy; or, the lattice constant of the top layer is The constant is highly matched with AlN or AlGaN, and the top layer of the 2D material ultra-thin interposer is grown with an AlGaN or AlN nucleation auxiliary layer by van der Waals epitaxy, and then has a GaN single crystal epitaxial layer on the AlGaN or AlN nucleation auxiliary layer.

The thickness of the 2D material ultra-thin interposer is greater than 0.5 nm.

The 2D material ultra-thin interposer is a 2D layer suitable for GaN, AlGaN or AlN epitaxy.

The 2D material ultra-thin interposer has a single-layer structure with only a top layer, and the top layer is a 2D material suitable for GaN, AlGaN or AlN epitaxy.

The 2D material ultra-thin interposer is a composite layer structure formed by a top layer and a bottom layer, the top layer is a 2D material suitable for AlN, AlGaN or GaN epitaxy, and the bottom layer is a 2D material suitable for a single crystal base layer.

The top layer adopts WS ₂ or MoS ₂ ; the bottom layer adopts hBN.

The single-layer structure or composite-layer structure of the 2D material ultra-thin interposer has a top lattice constant a that does not match AlN, AlGaN or GaN by more than 20% and is suitable for AlN, AlGaN or GaN epitaxy.

At least the top layer of the polycrystalline 2D material ultra-thin interposer is composed of two crystalline domains with matching directions at an angle of 60 degrees.

A silicon dioxide (SiO ₂ ) layer is added between the surface of the monocrystalline silicon substrate and the polycrystalline 2D material ultra-thin interposer to improve the dielectric properties of the silicon substrate and improve the application performance of high-frequency components.

After adopting the above scheme, the present invention can firstly grow layers with good crystallinity on the c-plane sapphire surface of single crystal by means of the application of polycrystalline 2D material ultra-thin interposer and van der Waals epitaxy (VDWE). Two (0° and 60°) crystalline domains point to the polycrystalline 2D material layer; the 2D material layer is transferred to the surface of the single crystal silicon substrate to form a surface lattice constant that is highly matched to AlN, AlGaN and GaN. The substrate can effectively overcome the defect quality problem of the gallium nitride layer caused by the mismatch of the heteroepitaxial lattice; the characteristics of the van der Waals junction can alleviate some of the thermal stress problems caused by different thermal expansion coefficients. Therefore, the substrate structure of the present invention is advantageous for growing high-quality GaN epitaxial layers for the fabrication of GaN-based and other wide-energy-gap optoelectronic and semiconductor components.

Description of drawings

1 is a schematic diagram of a gallium nitride (GaN-on-Si) structure on a silicon wafer in the prior art;

FIG. 2 is a schematic structural diagram of Embodiment 1 of the present invention;

3 is a schematic structural diagram of Embodiment 2 of the present invention;

4 is a schematic structural diagram of Embodiment 3 of the present invention;

5 is a schematic structural diagram of Embodiment 4 of the present invention;

FIG. 6 is a schematic structural diagram of Embodiment 5 of the present invention.

Detailed ways

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

Please refer to FIGS. 2 to 6 , which are several embodiments of the gallium nitride on silicon GaN-on-Si epitaxial substrate with a 2D material intermediate layer disclosed in the present invention.

As shown in the first embodiment shown in FIG. 2 , the GaN-on-Si epitaxial substrate of gallium nitride on silicon with a 2D material intermediate layer includes a single crystal silicon wafer substrate 1; 2D material ultra-thin interposer, the polycrystalline 2D material ultra-thin interposer has only one top layer 21, that is, the 2D material ultra-thin interposer has a single-layer structure, and the top layer 21 is a 2D material suitable for GaN epitaxy, The lattice constant of the top layer 21 is highly matched with GaN; a GaN single crystal epitaxial layer 3 is grown on the top layer 21 of the 2D material ultra-thin interposer by van der Waals epitaxy.

In the second embodiment shown in FIG. 3 , in the first embodiment, the 2D material ultra-thin interposer adopts a composite layer structure instead of a single-layer structure, that is, the 2D material ultra-thin interposer is formed by the top layer 21 and the bottom layer 22 . The top layer 21 is a 2D material suitable for GaN epitaxy, the lattice constant of the top layer 21 is highly matched with GaN, and the bottom layer 22 is a 2D material suitable for use as a single crystal base layer; the top layer 21 of the ultra-thin interlayer of 2D material is made of van der Waals. The GaN single crystal epitaxial layer 3 is epitaxially grown.

As shown in the third embodiment shown in FIG. 4 , the GaN-on-Si epitaxial substrate of gallium nitride on silicon with a 2D material intermediate layer includes a single crystal silicon wafer substrate 1; 2D material ultra-thin interposer, the polycrystalline 2D material ultra-thin interposer has only one top layer 21, that is, the 2D material ultra-thin interposer has a single-layer structure, and the top layer 21 is a 2D material suitable for AlN or AlGaN epitaxy Material, the lattice constant of the top layer 21 is highly matched with AlN or AlGaN; the top layer 21 of the 2D material ultra-thin interlayer is grown with an AlGaN or AlN nucleation auxiliary layer 4 by van der Waals epitaxy, and then the AlGaN or AlN nucleation auxiliary layer 4 has a nucleation auxiliary layer 4. GaN single crystal epitaxial layer 3 .

As shown in the fourth embodiment shown in FIG. 5 , the GaN-on-Si epitaxial substrate of gallium nitride on silicon with a 2D material intermediate layer includes a single crystal silicon wafer substrate 1; 2D material ultra-thin interposer, the 2D material ultra-thin interposer is a composite layer structure formed by a top layer 21 and a bottom layer 22, the top layer 21 is a 2D material suitable for AlN or AlGaN epitaxy, and the lattice constant of the top layer 21 is the same as that of AlN or AlGaN. Highly matched, the bottom layer 22 is a 2D material suitable as a single crystal base layer; the top layer 21 of the 2D material ultra-thin interlayer is grown with an AlGaN or AlN nucleation auxiliary layer 4 by van der Waals epitaxy, and then on the AlGaN or AlN nucleation auxiliary layer 4 It has a GaN single crystal epitaxial layer 3 .

As shown in FIG. 6 , the fifth embodiment is different from the first embodiment in that a silicon dioxide (SiO ₂ ) layer 5 is added between the surface 1 of the single crystal silicon substrate and the ultra-thin interposer of the polycrystalline 2D material, so as to Improve the dielectric properties of silicon substrates and improve the application performance of high-frequency components. Specifically, a silicon dioxide (SiO ₂ ) layer 5 is covered on the silicon wafer substrate 1 , and a polycrystalline 2D material ultra-thin interposer is placed on the silicon dioxide (SiO ₂ ) layer 5 . The material ultra-thin interposer has only one top layer 21, that is, the 2D material ultra-thin interposer has a single-layer structure, the top layer 21 is a 2D material suitable for GaN epitaxy, and the lattice constant of the top layer 21 is highly matched with GaN; the 2D material is ultra-thin A GaN single crystal epitaxial layer 3 is grown on the top layer 21 of the interposer by van der Waals epitaxy. Of course, in the present invention, a silicon dioxide (SiO ₂ ) layer 5 can also be added between the surface 1 of the single crystal silicon substrate and the ultra-thin interposer of the polycrystalline 2D material in the second to fourth embodiments to improve the dielectric properties of the silicon substrate , to improve the application performance of high-frequency components. This article does not illustrate one by one.

The optimal design of the 2D material ultra-thin interposer of the present invention is that the thickness is greater than 0.5 nm. The 2D material ultra-thin interposer is a 2D layer suitable for GaN, AlGaN or AlN epitaxy. Wherein, the top layer 21 can be made of WS ₂ or MoS ₂ or the like; the bottom layer 22 can be made of hBN or the like.

Table 2

Material	Lattice constant a(nm)
Hexagonal Boron Nitride hBN	0.25
graphene graphene	0.246
WS 2	0.318
MoS 2	0.3161
WSe 2	0.3297
MoSe 2	0.3283

The lattice constant a of the top layer 21 of the single-layer structure or the composite layer structure of the 2D material ultra-thin interposer does not match AlN, AlGaN or GaN by more than 20% and is suitable for AlN, AlGaN or GaN epitaxy. At least the top layer 21 of the polycrystalline 2D material ultra-thin interposer is composed of two crystalline domains with matching directions at an angle of 60 degrees.

The preparation method of the gallium nitride on silicon GaN-on-Si epitaxial substrate with the 2D material intermediate layer of the present invention, the steps are as follows:

Step 1, using a silicon single crystal substrate (chip) that conforms to the epitaxial growth grade as the starting material, and undergoes appropriate pretreatment (including chip cleaning) as the preparation for the subsequent manufacturing process;

Step 2, growing a polycrystalline 2D material layer on the surface of the c-plane sapphire chip with an existing manufacturing process;

Step 3, using the existing process to peel off the applicable 2D layer from the sapphire surface after growing, and transfer it to the surface of the silicon single crystal substrate;

In step 4, using the van der Waals epitaxy technique, subsequent GaN epitaxy can be continued on the silicon single crystal substrate with the polycrystalline 2D material layer on the surface in step 3;

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. It should be pointed out that after reading this specification, the equivalent changes made by those skilled in the art according to the design ideas of this case all fall into the protection scope of this case.

Claims (10)

1. A gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material intermediate layer is characterized by comprising a single crystal silicon wafer substrate;

   A polycrystalline 2D material ultra-thin interposer on the silicon wafer substrate, and the polycrystalline 2D material ultra-thin interposer has at least one top layer;

   The lattice constant of the top layer is highly matched with AlN, AlGaN or GaN; wherein, the lattice constant of the top layer is highly matched with GaN, and a GaN single crystal epitaxial layer is grown on the top layer of the 2D material ultra-thin interlayer by van der Waals epitaxy; or, the lattice constant of the top layer is The constant is highly matched with AlN or AlGaN, and the top layer of the 2D material ultra-thin interposer is grown with an AlGaN or AlN nucleation auxiliary layer by van der Waals epitaxy, and then has a GaN single crystal epitaxial layer on the AlGaN or AlN nucleation auxiliary layer.
2. The gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material interlayer according to claim 1, wherein the thickness of the 2D material ultra-thin interlayer is greater than 0.5 nm.
3. The gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material interlayer according to claim 1, wherein the 2D material ultra-thin interposer is a 2D layer suitable for GaN, AlGaN or AlN epitaxy .
4. The gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material interlayer according to claim 1, wherein the 2D material ultra-thin interlayer is a single-layer structure with only a top layer, and the top layer is suitable for 2D materials for GaN, AlGaN or AlN epitaxy.
5. The gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material interlayer according to claim 1, wherein the 2D material ultra-thin interlayer is a composite layer structure formed by a top layer and a bottom layer, and the top layer is a composite layer structure. To be a 2D material suitable for AlN, AlGaN or GaN epitaxy, the underlying layer is a 2D material suitable as a single crystal base layer.
6. The gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material interlayer according to claim 4 or 5, wherein the 2D material ultra-thin interlayer has a single-layer structure or a top layer of a composite layer structure The lattice constant a does not match AlN, AlGaN or GaN by more than 20% and is suitable for AlN, AlGaN or GaN epitaxy.
7. The gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material intermediate layer according to claim 4 or 5, wherein the top layer adopts WS ₂ or MoS ₂ .
8. The gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material intermediate layer according to claim 5, wherein the bottom layer is hBN.
9. The gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material interlayer according to claim 1, characterized in that: at least the top layer of the polycrystalline 2D material ultra-thin interlayer is composed of two kinds of 60-degree interlayers. It consists of crystallized regions with matching orientations.
10. The gallium nitride-on-silicon GaN-on-Si epitaxial substrate with a 2D material interlayer according to claim 1, characterized in that: a polycrystalline 2D material ultra-thin interlayer is added between the surface of the single crystal silicon substrate and the polycrystalline 2D material ultra-thin interlayer. Silica _SiO2 layer.

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