CN116732607A - Nitride epitaxial structure, epitaxial growth method and application thereof - Google Patents

Abstract

The application discloses a nitride epitaxial structure, an epitaxial growth method and application thereof. The nitride epitaxial structure comprises a hexagonal boron nitride layer, a single-layer amorphous boron nitride layer and a nitride semiconductor layer which are sequentially stacked; the nitride semiconductor layer is formed by the growth of the hexagonal boron nitride layer through remote epitaxy. The epitaxial growth method comprises the following steps: growing a hexagonal boron nitride layer on the substrate; growing a single-layer amorphous boron nitride layer; and growing a nitride semiconductor layer. According to the epitaxial growth method of the nitride semiconductor layer based on the in-situ growth single-layer amorphous boron nitride/hexagonal boron nitride composite insertion layer, provided by the application, a plurality of layers of hexagonal boron nitride are used as a polar bottom layer to be matched with the single-layer amorphous boron nitride layer, so that a high-quality single crystal nitride film with low grain boundary defects, low mismatch dislocation and low stress is remotely grown on any substrate in an epitaxial manner; in addition, the hexagonal boron nitride/epitaxial substrate after the epitaxial layer is stripped can be recycled, and the material cost can be reduced.

Description

Nitride epitaxial structure, epitaxial growth methods and their applications

Technical field

The present invention relates to the technical field of semiconductor preparation processes, in particular to the field of nitride and crystal growth, and in particular to a nitride epitaxial structure, an epitaxial growth method and its application.

Background technique

As representatives of the third generation of semiconductor materials, wide bandgap semiconductor materials such as gallium nitride (GaN) and aluminum nitride (AlN) have the advantages of high breakdown field strength, thermal conductivity and electron mobility. They are the next generation of optoelectronics in the future. , core foundation of power electronics and high-frequency microelectronics.

At present, epitaxial nitride single crystal films and devices mostly use heteroepitaxial growth methods, such as sapphire (Al ₂ O ₃ ), silicon carbide (SiC), silicon (Si), etc. as substrates for epitaxial growth. However, due to the large lattice mismatch and thermal expansion coefficient mismatch in heteroepitaxial growth, large stress, defects and even cracks are usually generated during nitride epitaxial growth, thus affecting the preparation of subsequent devices.

In order to solve the above problems, in recent years, more and more attention has been focused on two-dimensional materials, such as graphene, hexagonal boron nitride (h-BN), and transition metal dihalocarbons (TMDC). In 2017, Kim et al. from the Massachusetts Institute of Technology proposed a new epitaxy concept - remote epitaxy, believing that the polarity of the substrate will "penetrate" the single layer of graphene and act on the epitaxial layer, thus guiding the orientation of the epitaxial layer. It is beneficial to obtain single crystal semiconductor materials without grain boundary defects. They used first-principles calculations combined with experimental results to prove that remote epitaxy is achieved by an ionic substrate, and that the number of penetrable graphene layers is related to the ionic size of the substrate. However, current research progress requires the search for an appropriate substrate, especially the substrate with considerable ionicity to achieve the above-mentioned remote epitaxy, thus limiting the selection and application range of substrate materials.

Some existing technologies related to the above current situation disclose a variety of nitride epitaxy methods, such as:

On a single-layer graphene/6H-SiC (0001) substrate, a GaN nucleation layer was grown using the metal-organic chemical vapor deposition method MOCVD. In this technical solution, single-layer graphene may be destroyed by gases such as NH ₃ and H ₂ during the growth process, resulting in holes, thereby exposing the heterogeneous substrate and preventing graphene from fully exerting its ability to reduce stress. , The role of the substrate can be peeled off. (T Journot, et al. "Remote epitaxy using graphene enables growth of stress-free GaN." Nanotechnology 30 (2019) 505603.)

On a polycrystalline diamond substrate using an h-BN insertion layer, a low-temperature AlN buffer layer, a high-temperature AlN buffer layer, an AlGaN-I layer, and an AlGaN-II layer are grown sequentially, and finally a GaN film is grown at 1050°C, (002) half The height and width are 1.2°. (Wenqiang Xu, et al. "High quality GaN grown on polycrystalline diamond substrates with h-BN insertion laye rs by MOCVD." Materials Letters 305(2021)130806.)

CVD graphene used as a GaN film growth substrate was synthesized on Cu foil, the CVD graphene was transferred to the Si/SiO2 substrate, and then oxygen plasma treatment was performed on the surface. GaN films were epitaxially grown on CVD graphene using ZnO nanowalls as the interlayer. (Hyobin Yoo, et al. "Microstructures of GaN Thin Films Grown on Graphene Layers." Advanced Materials 24 (2012) 515-518.)

In the above two technical solutions, nitride is epitaxially grown on multi-layer graphene or h-BN. Due to the weak van der Waals force between graphene and nitride, more grain boundary defects will be generated in the nitride film, reducing the Crystal quality of the epitaxial layer.

On the (111) Si substrate, an AlN film was grown heteroepitaxially using metal organic chemical vapor deposition (MOCVD) technology. (A.P. Lange, et al. "Influence of trimethylaluminum predoses on the growthmorphology, film-s ubstrate interface, and microstructure of MOCVD-grown AlN on (111)Si." Journal of Crystal Growth 5 11 (2019) 106-117)

In the above technical solution, nitride is heteroepitaxially grown on sapphire (Al ₂ O ₃ ), silicon carbide (SiC), silicon (Si) and other substrates, and a large number of mismatch dislocations will be generated due to lattice mismatch and thermal mismatch. , reducing the crystal quality of the epitaxial layer.

The two-dimensional material layer formed by growing graphene or boron nitride on an AlN single crystal substrate is used as an insertion layer, and an LED epitaxial film layer is grown on the insertion layer; after peeling off, the composite epitaxial layer is transferred to the metal substrate to obtain a flexible Deep UV LED epitaxial structure. (Chinese invention patent: a flexible deep ultraviolet LED epitaxial structure and its preparation method, CN115172537A)

In the above technical solution, when the AlN intrinsic layer is grown on the two-dimensional material insertion layer, the high temperature will cause the decomposition of the substrate AlN and destroy the graphene or few-layer boron nitride two-dimensional insertion layer. When using multi-layer boron nitride, its polarity will affect the epitaxial layer AlN, resulting in a new lattice mismatch and causing greater stress in the AlN film. This solution limits the choice of epitaxial substrates and cannot obtain high-quality single-crystal AlN intrinsic layers.

After growing a graphene film on the patterned substrate, a boron nitride film is grown, and then an aluminum nitride film, a gallium nitride buffer layer, an AlGaN barrier layer and a gallium nitride cap layer are sequentially grown to obtain gallium nitride-based power. The epitaxial structure of the device. (Chinese invention patent: an epitaxial structure and preparation method of gallium nitride-based power devices, CN115411093A)

This solution uses multi-layer graphene and boron nitride films. Due to the weak van der Waals force between graphene and nitride, more grain boundary defects will be generated in the aluminum nitride film, reducing the crystal quality of aluminum nitride.

Polish and clean the copper substrate; grow an h-BN-graphene composite layer on the copper substrate; use atomic layer deposition to grow an aluminum nitride layer on the h-BN-graphene composite layer; on the aluminum nitride The gallium nitride layer is grown on the thin layer using metal-organic chemical vapor deposition. (Chinese invention patent: A method for preparing a gallium nitride epitaxial structure based on a hexagonal boron nitride-graphene composite layer as a buffer layer, CN107706274A)

Using metal-organic chemical vapor deposition to grow a gallium nitride layer on a thin aluminum nitride layer will produce misfit dislocations and reduce the crystal quality of the epitaxial gallium nitride layer.

Based on the above technical status, it is of great significance to develop a growth method that has broad substrate adaptability and can use remote epitaxy to obtain low stress, low defect density and exfoliable single crystal nitride materials.

Contents of the invention

In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a nitride epitaxial structure, an epitaxial growth method and their applications.

In order to achieve the foregoing invention objectives, the technical solutions adopted by the present invention include:

In a first aspect, the present invention provides a nitride epitaxial structure, which includes a hexagonal boron nitride layer, a single-layer amorphous boron nitride layer and a nitride semiconductor layer that are stacked in sequence;

The nitride semiconductor layer is formed by growing the hexagonal boron nitride layer through remote epitaxial growth.

In a second aspect, the present invention also provides an epitaxial growth method of a nitride semiconductor layer, which includes:

Grow a hexagonal boron nitride layer on the substrate;

Grow a single layer of amorphous boron nitride layer on the surface of the hexagonal nitride layer;

A nitride semiconductor layer is grown on the surface of the single-layer amorphous boron nitride layer.

In a third aspect, the present invention also provides a nitride semiconductor layer produced by the above epitaxial growth method.

In a fourth aspect, the present invention also provides a nitride semiconductor device, which includes the above-mentioned nitride epitaxial structure or nitride semiconductor layer.

Based on the above technical solution, compared with the existing technology, the beneficial effects of the present invention at least include:

The invention provides an epitaxial growth method for a nitride semiconductor layer based on the in-situ growth of a single layer of amorphous boron nitride/hexagonal boron nitride composite insertion layer. The multilayer hexagonal boron nitride is used as the polar bottom layer, and a single layer of hexagonal boron nitride is used as the polar bottom layer. An amorphous boron nitride layer realizes remote epitaxial growth of high-quality single crystal nitride films with low grain boundary defects, low misfit dislocations, and low stress. The choice of substrate is arbitrary and is not limited to specific ions. flexible substrate; in addition, the hexagonal boron nitride/epitaxial substrate after the epitaxial layer is peeled off can be repeatedly used, which can reduce material costs.

The above description is only an overview of the technical solutions of the present invention. In order to enable those skilled in the art to more clearly understand the technical means of the present application and implement them in accordance with the contents of the description, the following is a detailed description of the preferred embodiments of the present invention. The description of the drawings is as follows.

Description of drawings

Figure 1 is a schematic process flow diagram of an epitaxial growth method provided by a typical implementation case of the present invention;

FIG. 2 is a schematic structural diagram of a nitride epitaxial structure provided in a typical embodiment of the present invention.

Detailed ways

In view of the deficiencies in the prior art, the inventor of this case was able to propose the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principles will be further explained below.

Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described here. Therefore, the protection scope of the present invention is not limited to the specific implementation disclosed below. Example limitations.

Furthermore, relative terms such as "first" and "second" are merely used to distinguish one component or method step from another with the same name and do not necessarily require or imply that such components or method steps are mutually exclusive. any such actual relationship or sequence exists between them.

Ultrathin amorphous BN (boron nitride, the same below) was first reported as a dielectric material for two-dimensional nanoelectronics in 2016. For example, pulsed laser deposition (PLD) can be used to deposit 1-5 nm amorphous BN on various substrates. And the deposition temperature can reach below 200℃. The amorphous BN film is amorphous, has no obvious long-range ordered structure, and does not have polarity caused by the crystal structure. This means that the orientation of remote epitaxial GaN using a single layer of amorphous BN is completely controlled by the substrate and will not Creates an additional phase and is more stable at high temperatures than graphene.

Unlike single-layer amorphous BN, h-BN is not only a layered two-dimensional material, but also ionic (0.256). Its ionicity is greater than the SiC substrate that has been proven to be able to implement nitride remote epitaxy (ionicity 0.177). Therefore, the present invention creatively combines the characteristics of the above two materials and through long-term practice, proposes a nitride growth method for in-situ growth of a single layer of amorphous boron nitride/hexagonal boron nitride composite insertion layer to obtain low Stress, low defect density and exfoliable single crystal nitride materials.

Specifically, as shown in Figures 1 and 2, embodiments of the present invention provide a nitride epitaxial structure, which includes a hexagonal boron nitride layer, a single-layer amorphous boron nitride layer, and a nitride semiconductor layer that are stacked in sequence; The nitride semiconductor layer is formed by growing the hexagonal boron nitride layer through remote epitaxial growth.

The prior art discloses some nitride epitaxial growth schemes using hexagonal boron nitride as a buffer layer. For example, some prior art discloses growing a hexagonal boron nitride layer first, and then forming an aluminum nitride layer on its surface by MOCVD. Technical solutions to continue growing the gallium nitride layer on the surface of the aluminum nitride layer. In these technical solutions, due to the lack of a single layer of amorphous boron nitride layer, ionic remote epitaxial growth using hexagonal boron nitride cannot be achieved. nitride semiconductor layer, and thus cannot obtain high-quality epitaxial layers obtained by remote epitaxy. The essential explanation is that in the technical solution of first growing an aluminum nitride layer and then growing a gallium nitride layer, there is still a lattice mismatch between aluminum nitride and gallium nitride, which will reduce the quality of the epitaxial layer. The polarity produced by a single layer of amorphous boron nitride due to its lack of crystal structure plays a role similar to that of a single layer of graphene. Multilayer hexagonal boron nitride serves as a two-dimensional layered polar substrate, and its polarity can penetrate Single layer amorphous boron nitride, remote epitaxial single crystal nitride film. During the remote epitaxy process, the epitaxial layer spontaneously relaxes. This unique relaxation phenomenon can significantly reduce the dislocations caused by the lattice mismatch between the epitaxial nitride and the underlying hexagonal boron nitride. However, when single-layer graphene is routinely used in this field Although it can also produce remote epitaxy, it will face other problems and cannot fully exert the control effect of film growth quality. Therefore, in the present invention, a single layer of amorphous boron nitride is specifically used to achieve remote epitaxy, and high-quality single crystal nitride films can be realized.

In some embodiments, the hexagonal boron nitride layer is disposed on the surface of the substrate.

In some embodiments, the substrate is made of any one or a combination of two or more of sapphire, silicon carbide, silicon, and diamond.

In some embodiments, the material of the nitride semiconductor layer includes any one or a combination of gallium nitride and aluminum nitride.

In some embodiments, the thickness of the hexagonal boron nitride layer is 20-100 nm.

In some embodiments, the nitride semiconductor layer has a thickness of 500 nm-3 μm.

Continuing to refer to Figure 1, an embodiment of the present invention also provides an epitaxial growth method of a nitride semiconductor layer, which includes the following steps:

A hexagonal boron nitride layer is grown on the substrate.

A single layer of amorphous boron nitride layer is grown on the surface of the hexagonal nitride layer.

A nitride semiconductor layer is grown on the surface of the single-layer amorphous boron nitride layer.

Among the above technical solutions, embodiments of the present invention provide a nitride growth method based on in-situ growth of a single layer of amorphous boron nitride/hexagonal boron nitride composite insertion layer to obtain low stress, low defect density and peelable of single crystal nitride materials. First, multiple layers of hexagonal boron nitride are grown in situ on the substrate, and then a single layer of amorphous boron nitride is generated. Through remote epitaxy, a single crystal nitride material with low stress, low defect density and exfoliation is obtained.

In some embodiments, the hexagonal boron nitride layer and the single-layer amorphous boron nitride layer are grown continuously in a chamber of the same growth equipment.

In some embodiments, the single layer of amorphous boron nitride is grown in situ on the surface of the hexagonal boron nitride layer.

In some embodiments, the hexagonal boron nitride layer and the single-layer amorphous boron nitride layer are grown using any one of metal-organic chemical vapor deposition and molecular beam epitaxy.

In some embodiments, it specifically includes the following steps:

The hexagonal boron nitride layer is grown under the conditions of the first temperature and the first nitrogen-to-boron ratio, and the growth time is 20-40 minutes.

The single-layer amorphous boron nitride layer is grown under the conditions of the second temperature and the second nitrogen-to-boron ratio, and the growth time is 5-20 s.

Wherein, the first temperature is higher than the second temperature, and the first nitrogen-to-boron ratio is lower than the second nitrogen-to-boron ratio.

In some embodiments, the first temperature is 650-750°C and the second temperature is 200-350°C.

In the present invention, the single-layer amorphous nitride layer formed is more important. The single-layer amorphous nitride layer should be grown by accurately controlling the growth temperature and time, especially at a lower temperature that needs to be controlled. The growth time is precisely controlled in seconds to form a single controllable amorphous layer on the surface of the hexagonal boron nitride layer. As some typical application examples of the above technical solutions, the epitaxial growth method can be implemented using the following specific steps:

S1: Prepare the substrate. The substrate selection is arbitrary, such as sapphire (Al ₂ O ₃ ), silicon carbide (SiC), silicon (Si), diamond substrate, etc.

S2: Generate a hexagonal boron nitride layer. The hexagonal boron nitride layer is epitaxially grown directly on the substrate using metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), etc., and the thickness can be, for example, 20-100 nm.

S3: Generate a single layer of amorphous boron nitride. In the same reaction chamber where the hexagonal boron nitride layer was generated in step S2, by adjusting the process parameters, continue to grow a single layer of amorphous boron nitride to a thickness of about 0.34nm. This thickness is determined by the lattice parameters of boron nitride. .

S4: Growth of single crystal nitride film. In the same reaction chamber as steps S2 and S3, at a temperature of 1050°C, first pass H ₂ for 10 minutes to clean the substrate surface. Then directly epitaxially grow gallium nitride or aluminum nitride single crystal films in one step, or grow aluminum nitride, gallium nitride stacks, or different gallium nitride stacks (such as gallium nitride nucleation layer + nitrogen The growth temperature of the gallium intrinsic layer) may be, for example, 1000-1100°C, and the growth time may be 0.5-2 h, but is not limited thereto.

In the above steps, the key technical means is to use a single layer of amorphous boron nitride/hexagonal boron nitride layer as a composite insertion layer for remote epitaxy to obtain a high-quality single crystal nitride film, that is, a single layer of amorphous boron nitride. The nitride semiconductor layer is epitaxially grown on the hexagonal boron nitride composite insertion layer, and how to grow the nitride semiconductor layer in step S4 is not absolutely limited to the preferred embodiments exemplified above.

In the above exemplary technical solution, the nitride material is epitaxially grown in a single-layer amorphous boron nitride/multi-layer hexagonal boron nitride composite insertion layer, in which the multi-layer hexagonal boron nitride serves as a two-dimensional layered polar bottom layer, and its polarity It can penetrate single-layer amorphous boron nitride and remotely epitaxial single-crystal nitride films. The growth of the nitride in the epitaxial layer is completely controlled by the multi-layer hexagonal boron nitride layer below. While ensuring the single crystallinity of the epitaxial layer, there are no ionic requirements for the selection of the epitaxial substrate. It is arbitrary and can be widely adapted to various substrates.

The method of growing multi-layer hexagonal boron nitride, single-layer amorphous boron nitride and epitaxial nitride in situ on the substrate can prevent contamination, wrinkles and tears caused by two-dimensional graphene or boron nitride during the transfer process. crack. At the same time, it can also avoid contamination caused by the transfer process when the substrate is transferred to different reaction chambers for growth.

The amorphous boron nitride/hexagonal boron nitride composite layer has more high-temperature stability than graphene and can epitaxial nitride materials at higher temperatures without being destroyed by gases such as NH ₃ and H ₂ .

A third aspect of the embodiment of the present invention also provides a nitride semiconductor layer produced by the above epitaxial growth method.

In some embodiments, the nitride semiconductor layer is separated from the substrate through lift-off.

A fourth aspect of the embodiment of the present invention is a nitride semiconductor device, which includes the above-mentioned nitride epitaxial structure or the above-mentioned nitride semiconductor layer.

In some embodiments, the nitride semiconductor device includes a nitride laser.

In some embodiments, the nitride laser includes a substrate, a hexagonal boron nitride layer, a single-layer amorphous boron nitride layer, an aluminum nitride layer, a gallium nitride buffer layer, and an N-type gallium nitride layer stacked in sequence. , N-type cladding layer, N-type waveguide layer, active area multiple quantum well layer, P-type waveguide layer, P-type cladding layer, P-type gallium nitride layer.

The technical solutions of the present invention are further described in detail below through several examples. However, the examples selected are only for illustrating the invention and do not limit the scope of the invention.

Example 1

This embodiment illustrates a nitride growth method based on a single-layer amorphous boron nitride insertion layer, including the following process steps:

(1) Polish and clean the copper substrate and put it into the MBE equipment.

(2) Deposit multiple layers of hexagonal boron nitride (h-BN) at 700°C, bombard with ions at Ar:N ₂ =50:50, the flux is 0.12m A/cm ² , and the boron deposition rate is: Ion energy: 500eV, growth for 30 minutes, and its thickness is about 50nm.

(3) Reduce the temperature to 300°C, bombard ions with Ar:N ₂ =50:50, the flux is 0.28mA/cm ² , and the boron deposition rate is: 0. Ion energy: 500eV. By precisely controlling the growth time to 15 seconds, a single-layer amorphous BN layer with a thickness of approximately 0.34nm was obtained.

(4) Raise the temperature to 700°C. Plasma power 500W. Growth was performed for 20 minutes at a Ga/N ratio of 1.0% to promote the nucleation of GaN on the single layer of amorphous BN. Then complete growth of GaN was started under the condition of Ga/N of 1.9%, forming a gallium nitride semiconductor layer with a thickness of 2 μm.

The gallium nitride semiconductor layer was characterized and tested, and the internal stress was 0.045GPa, and the dislocation density was 6.2×10 ⁷ cm ^-2 ; and, the gallium nitride semiconductor layer provided in this embodiment can be peeled off through thermal release tape.

Example 2

A nitride growth method based on a single-layer amorphous boron nitride insertion layer. This embodiment includes the following process steps:

(1) Place the silicon substrate into the MBE equipment.

(2) Deposit multiple layers of hexagonal boron nitride at 700°C.

(3) Reduce the temperature to 300°C and the RF plasma power to 250W. A single-layer amorphous BN layer is obtained by precisely controlling the growth time.

(4) Raise the temperature to 700°C. Plasma power was increased to 500W. Growth was performed under nitrogen-rich conditions for 20 min to promote the nucleation of GaN on a single layer of amorphous BN. The gallium flux is then increased to initiate full growth of GaN under gallium-rich conditions.

Example 3

A nitride growth method based on a single-layer amorphous boron nitride insertion layer. This embodiment includes the following process steps:

(1) Polish and clean the copper substrate and put it into the MBE equipment.

(2) Deposit multiple layers of hexagonal boron nitride at 700°C.

(3) Reduce the temperature to 300°C and the RF plasma power to 250W. A single-layer amorphous BN layer is obtained by precisely controlling the growth time.

(4) Increase the temperature to 850°C. Plasma power was increased to 300W. Start the growth of a thin layer of AlN.

Example 4

A nitride growth method based on a single-layer amorphous boron nitride insertion layer. This embodiment includes the following process steps:

(1) Place the silicon substrate into the MBE equipment.

(2) Deposit multiple layers of hexagonal boron nitride at 700°C.

(3) Reduce the temperature to 300°C and the RF plasma power to 250W. A single-layer amorphous BN layer is obtained by precisely controlling the growth time.

(4) Increase the temperature to 850°C. Plasma power was increased to 300W. Start the growth of a thin layer of AlN.

Examples 2-4 all obtained nitride films similar to Example 1, and such nitride films all had better film quality than existing nitride film growth methods, including but not Limited to lower internal stress and lower dislocation density.

Example 5

The technical solution of the present invention also provides a semiconductor device structure prepared based on the above method, wherein the structure from bottom to top is: copper substrate, h-BN layer, single-layer amorphous BN layer, aluminum nitride layer and a gallium nitride layer; the thickness of h-BN is 20-100nm, and the preferred thickness of h-BN is 80nm; the thickness of the aluminum nitride layer is 20-100nm, and the preferred thickness of the aluminum nitride layer is 80nm; nitriding The thickness of the gallium layer is 1-5 μm, and the preferred thickness of the gallium nitride layer is 3 μm.

Based on the above semiconductor device structure, this embodiment also prepares a laser with a structure based on the above method. The structure of the laser is as follows: sequentially growing an h-BN layer, a single layer of amorphous BN layer, and aluminum nitride on a copper substrate. layer, gallium nitride buffer layer, N-type gallium nitride layer, N-type cladding layer, N-type waveguide layer, active region multiple quantum well layer, P-type waveguide layer, P-type cladding layer, P-type gallium nitride layer, Form a gallium nitride laser structure.

Comparative example 1

This comparative example is generally the same as Example 1, and the main differences are:

The step (3) of growing a single layer of amorphous boron nitride is replaced by taking out the substrate and using magnetron sputtering to form an aluminum nitride nucleation layer instead of the single layer of amorphous boron nitride. The aluminum nitride nucleation layer The thickness is about 20nm.

The disadvantages of this epitaxial method are: ① After growing multiple layers of boron nitride, and then magnetron sputtering the aluminum nitride nucleation layer, contamination will be caused during the substrate transfer process. ②Growing a gallium nitride layer on the aluminum nitride nucleation layer will generate misfit dislocations and reduce the crystal quality of the epitaxial layer gallium nitride.

After characterization, the internal stress of the obtained gallium nitride semiconductor layer is 0.409GPa, and the dislocation density is 9.4×10 ⁷ cm ^-2 .

Comparative example 2

This comparative example is generally the same as Example 1, and the main differences are:

The step of growing a single layer of amorphous boron nitride in step (3) is replaced without removing the substrate, and the same deposition process is continued in the same chamber to form an aluminum nitride nucleation layer instead of the single layer of amorphous boron nitride layer. The thickness of the aluminum nitride nucleation layer is about 20nm.

This epitaxial method grows a gallium nitride layer on an aluminum nitride nucleation layer, which will produce misfit dislocations and reduce the crystal quality of the epitaxial layer gallium nitride.

After characterization, the internal stress of the obtained gallium nitride semiconductor layer is 0.387GPa, and the dislocation density is 9.0×10 ⁷ cm ^-2 .

Comparative example 3

This comparative example is generally the same as Example 1, and the main differences are:

The step of growing a single layer of amorphous boron nitride in step (3) is eliminated, and a gallium nitride epitaxial layer is directly grown on the hexagonal boron nitride layer.

After characterization, the internal stress of the obtained gallium nitride semiconductor layer is 0.605GPa, and the dislocation density is 1.2×10 ⁸ cm ^-2 .

This shows that without the single-layer amorphous boron nitride layer, the ionicity of the hexagonal boron nitride layer cannot control the growth process of the gallium nitride layer through remote epitaxy, resulting in significant internal stress and defects in the gallium nitride layer. deterioration.

Comparative example 4

This comparative example is generally the same as Example 1, and the main differences are:

The step (3) of growing a single layer of amorphous boron nitride is replaced by growing a single layer of graphene using the CVD method.

The disadvantages of this epitaxial method are: ① The growth of boron nitride and graphene needs to be completed in different chambers, and the transfer process in different chambers will also bring contamination to the substrate. ② When growing gallium nitride at high temperature, the growth gas source such as NH ₃ can easily destroy graphene, thus affecting the epitaxial quality.

After characterization, the internal stress of the obtained gallium nitride semiconductor layer is 0.584GPa, and the dislocation density is 1.0×10 ⁸ cm ^-2 .

Comparative example 5

This comparative example is generally the same as Example 1, and the main differences are:

Extend the time for growing a single layer of amorphous boron nitride in step (3) to grow into a multi-layer amorphous boron nitride with a thickness of about 10 nm.

In this epitaxial method, due to the weak van der Waals force between multi-layer amorphous boron nitride and nitride, more grain boundary defects will be generated in the nitride film, reducing the crystal quality of the epitaxial layer.

After characterization, the internal stress of the obtained gallium nitride semiconductor layer is 0.623GPa, and the dislocation density is 1.3×10 ⁸ cm ^-2 .

The above comparative example shows that the thickness and material of the film layer between the hexagonal boron nitride layer and the nitride semiconductor layer are important technical features to achieve effective remote epitaxial control of the epitaxially grown nitride semiconductor layer by hexagonal boron nitride. Effective remote extension is not possible without either feature.

Based on the above embodiments and comparative examples, it can be understood that the epitaxial growth method of the nitride semiconductor layer based on the in-situ growth of a single layer of amorphous boron nitride/hexagonal boron nitride composite insertion layer provided by the embodiment of the present invention can Multilayer hexagonal boron nitride serves as the polar bottom layer, combined with a single layer of amorphous boron nitride layer, to achieve remote epitaxial growth of high-quality single crystal nitride films with low grain boundary defects, low misfit dislocations, and low stress; in addition, The hexagonal boron nitride/epitaxial substrate after the epitaxial layer is peeled off can be used repeatedly, which can reduce material costs.

It should be understood that the above embodiments are only to illustrate the technical concepts and characteristics of the present invention. Their purpose is to enable those familiar with the technology to understand the content of the present invention and implement it accordingly, and cannot limit the scope of protection of the present invention. All equivalent changes or modifications made based on the spirit and essence of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A nitride epitaxial structure, characterized in that it includes a hexagonal boron nitride layer, a single-layer amorphous boron nitride layer and a nitride semiconductor layer that are stacked in sequence; The nitride semiconductor layer is formed by growing the hexagonal boron nitride layer through remote epitaxial growth. 2. The nitride epitaxial structure according to claim 1, wherein the hexagonal boron nitride layer is disposed on the surface of the substrate; Preferably, the material of the substrate includes any one or a combination of two or more of sapphire, silicon carbide, silicon, and diamond; And/or, the material of the nitride semiconductor layer includes any one or a combination of gallium nitride and aluminum nitride. 3. The nitride epitaxial structure according to claim 1, wherein the thickness of the hexagonal boron nitride layer is 20-100 nm; Preferably, the thickness of the nitride semiconductor layer is 500 nm-3 μm. 4. An epitaxial growth method of a nitride semiconductor layer, characterized by comprising: Grow a hexagonal boron nitride layer on the substrate; Grow a single layer of amorphous boron nitride layer on the surface of the hexagonal nitride layer; A nitride semiconductor layer is grown on the surface of the single-layer amorphous boron nitride layer. 5. The epitaxial growth method according to claim 4, characterized in that the hexagonal boron nitride layer and the single-layer amorphous boron nitride layer are continuously grown in a chamber of the same growth equipment; And/or, the single-layer amorphous boron nitride layer is grown in situ on the surface of the hexagonal boron nitride layer. 6. The epitaxial growth method according to claim 5, characterized in that the hexagonal boron nitride layer and the single-layer amorphous boron nitride layer are carried out by any one of metal organic chemical vapor deposition and molecular beam epitaxy. grow. 7. The epitaxial growth method according to claim 6, characterized in that it specifically includes: Under the conditions of the first temperature and the first nitrogen-to-boron ratio, the hexagonal boron nitride layer is grown, and the growth time is 20-40 minutes; Under the conditions of the second temperature and the second nitrogen-to-boron ratio, grow the single-layer amorphous boron nitride layer for a growth time of 5-20 s; Wherein, the first temperature is higher than the second temperature, and the first nitrogen-to-boron ratio is lower than the second nitrogen-to-boron ratio. 8. The epitaxial growth method according to claim 7, wherein the first temperature is 650-750°C, and the second temperature is 200-350°C. 9. The nitride semiconductor layer produced by the epitaxial growth method according to any one of claims 4 to 8; Preferably, the nitride semiconductor layer is separated from the substrate through peeling. 10. A nitride semiconductor device, characterized by comprising the nitride epitaxial structure according to any one of claims 1-3 or the nitride semiconductor layer according to claim 9; Preferably, the nitride semiconductor device includes a nitride laser; Preferably, the nitride laser includes a sequentially stacked substrate, a hexagonal boron nitride layer, a single-layer amorphous boron nitride layer, an aluminum nitride layer, a gallium nitride buffer layer, an N-type gallium nitride layer, and an N-type gallium nitride layer. Covering layer, N-type waveguide layer, active area multiple quantum well layer, P-type waveguide layer, P-type cladding layer, P-type gallium nitride layer.