Heteroepitaxial GaN single crystal thin film with high heat dissipation capability and preparation method of heteroepitaxial GaN single crystal thin film

Abstract

The invention discloses a heteroepitaxial GaN single crystal thin film with high heat dissipation capability and a preparation method thereof, and belongs to the field of semiconductor thin films. The patterned AlN composite structure is constructed, the GaN single crystal thin film with high heat dissipation capability and low dislocation density is directly formed on the functional substrate with high thermal conductivity in an epitaxial mode, and the heat dissipation problem of a high-performance GaN device can be solved. According to the method, the Van der Waals force integration and two-dimensional material assisted modification technology is utilized, and low-damage and high-strength combination of the high-quality AlN template and the functional substrate is achieved; through innovative graphical design and selective region epitaxy, effective control of GaN crystal quality and construction of a super-efficient in-plane-vertical mixed heat dissipation path are synchronously realized. A material platform is provided for laser diodes driven by high current density, high-power electronic devices and the like, the working stability, reliability and service life of the laser diodes and the high-power electronic devices are expected to be improved, and the laser diodes and the high-power electronic devices are widely applied to power management, electric automobiles, consumer electronics, photovoltaic inversion and other high-power electronic devices.

Description

Technical Field

[0001] This invention relates to semiconductor thin film materials, specifically to a heteroepitaxial GaN single crystal thin film with high heat dissipation capability and its preparation method. Background Technology

[0002] Gallium nitride (GaN)-based semiconductors are key materials for fabricating high-performance optoelectronic devices (such as miniature light-emitting diodes or laser diodes) and high-power electronic devices (such as high electron mobility transistors), with wide applications in displays, communications, and energy. Currently, GaN devices are mainly fabricated through epitaxial growth on heterogeneous substrates such as sapphire (Al2O3), silicon (Si), or silicon carbide (SiC). However, as devices develop towards higher power and miniaturization, the inherently low thermal conductivity of these substrates (approximately 35 W / m·K for sapphire, approximately 150 W / m·K for silicon, and approximately 490 W / m·K for silicon carbide) has become a core bottleneck restricting performance improvement. The large amount of heat generated during device operation cannot be dissipated in time, leading to increased chip junction temperature and causing serious problems such as efficiency degradation, wavelength drift, and decreased reliability—the so-called "thermal barrier." To solve the heat dissipation problem, transferring the GaN epitaxial layer to a polycrystalline diamond substrate with a thermal conductivity exceeding 1000 W / m·K is considered a promising future technology approach with practical application potential. However, this approach faces two major challenges: (1) High thermal resistance at the heterogeneous integration interface: Low-temperature bonding technology introduces a low thermal conductivity interface layer, forming a new heat dissipation bottleneck; (2) Difficulty in direct epitaxy of high-quality GaN: There are huge differences in lattice and chemical properties between diamond and GaN, making it difficult to epitaxially obtain GaN single-crystal thin films with low dislocation density. Therefore, developing a new method for the direct growth of GaN single-crystal thin films with low dislocation density and high heat dissipation capacity on polycrystalline diamond substrates is of great significance for breaking through the thermal management limits of existing devices and promoting the development of next-generation high-performance GaN technology. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention proposes a heteroepitaxial GaN single crystal thin film with high heat dissipation capability and its preparation method.

[0004] One object of the present invention is to provide a method for preparing heteroepitaxial GaN single crystal thin films with high heat dissipation capability. The method for preparing a high heat dissipation heteroepitaxial GaN single crystal thin film of the present invention includes the following steps: 1) Preparation of AlN composite structure: a) Growth of transition metal chalcogenides on a growth substrate; b) Growing the first single-crystal AlN thin film on a transition metal chalcogenide; c) Place the above structure in water and use the capillary action of water molecules to break the interfacial adsorption between the transition metal chalcogenide and the growth substrate, completely peel off the first single crystal AlN film / transition metal chalcogenide from the growth substrate, and let it float on the water surface completely under the action of buoyancy and tension. d) Transfer a crystal orientation transition layer on a functional substrate, the crystal orientation transition layer having a long-range ordered lattice structure; e) A continuous and flat second single-crystal AlN film is grown on the crystal orientation transition layer, and the functional substrate, the crystal orientation transition layer and the second single-crystal AlN film form a support substrate. f) The first layer of single-crystal AlN film / transition metal chalcogenide floating on the water surface is retrieved and placed in the air to be heated and dried. The bottom surface of the first layer of single-crystal AlN film / transition metal chalcogenide is tightly bonded to the surface of the supporting substrate by van der Waals forces to form an AlN composite structure of first layer of single-crystal AlN film / transition metal chalcogenide / second layer of single-crystal AlN film / crystal orientation transition layer / functional substrate, which is used to adjust the crystal orientation. 2) Modification and graphical representation of AlN composite structures: a) The AlN composite structure is treated in a high-temperature ammonia atmosphere, where nitrogen atoms in the ammonia replace chalcogens in the transition metal chalcogens, thereby modifying the layered transition metal chalcogens and generating a bonded transition layer composed of interlayer covalently bonded transition metal nitrogen compounds, thus obtaining the modified AlN composite structure. b) The mask is processed by laser etching to form a two-dimensional periodic array of circular holes, thus obtaining the first patterned mask. c) Using the first patterned mask as a mask, the modified AlN composite structure is etched down to the surface of the functional substrate using inductively coupled plasma (ICP) or reactive ion etching (RIE). A two-dimensional periodically arranged array of circular holes is etched out in the modified AlN composite structure as an embedded vertical heat dissipation channel. The surface of the first unetched single-crystal AlN thin film is defined as the first region, and the surface of the etched functional substrate is defined as the second region. The etched regions correspond one-to-one with the array of circular holes in the first patterned mask, i.e., they have the same diameter, thus obtaining a patterned AlN composite structure to achieve stress release and prevent the regenerated long film from cracking. 3) Fabrication of the thermally conductive extension layer: a) A thermally conductive extended material with a layered structure and disordered in-plane orientation is grown on a patterned AlN composite structure by chemical vapor deposition (CVD) to cover a first region with low thermal conductivity, a second region with high thermal conductivity, and a sidewall connecting the first and second regions. b) Using a second patterned mask complementary to the pattern of the first patterned mask as a mask, the thermally conductive extension material grown above the first region is etched away, while the thermally conductive extension material on the second region and the sidewalls connecting the first and second regions is retained. The thermally conductive extension material has efficient in-plane thermal conductivity and connects the low thermal conductivity first region with the high thermal conductivity second region through sidewall interconnection to obtain a thermally conductive extension layer. The thermally conductive extension layer introduces new thermal conduction channels, avoiding the thermal conduction limitation problem introduced by the first single-crystal AlN film / bonding transition layer / second single-crystal AlN film in the vertical direction, thereby improving the thermal conductivity of the entire structure. 4) Preparation of single-crystal GaN template layer: GaN was grown on a patterned AlN composite structure with a thermally conductive extended layer using metal-organic chemical vapor deposition (MOCVD). The specific process involved altering the GaN growth mode by changing the growth temperature, V / III ratio, and growth pressure, leading to three-dimensional GaN growth, a transition region from three-dimensional to two-dimensional growth, and finally, two-dimensional GaN growth. In the second region, the exposed functional substrate with thermally conductive extended material inhibited GaN nucleation and growth, resulting in low nucleation density, random in-plane orientation of the nucleated GaN, and slow or no growth. The first region exposed the first single-crystal AlN film. Since GaN and AlN belong to the same nitride semiconductor material system, GaN nucleation density was high, and the nucleated GaN nucleation was relatively rapid. N and the first layer of single-crystal AlN below have the same ordered crystal orientation, that is, GaN has a single crystal structure. Since there is no problem of high index crystal planes being exposed at its edges, the growth rate is fast, that is, GaN grows in the first region. As growth proceeds, in the two stages of three-dimensional growth and the transition from three-dimensional growth to two-dimensional growth, the lateral and longitudinal growth rates of the single-crystal GaN component above the first region are higher than those of the second region with exposed high index crystal planes. As a result, after entering the two-dimensional growth mode, the single-crystal GaN component above the first region will wrap around and bury the second region, so that the two-dimensional GaN has a single crystal structure. That is, the two-dimensional GaN has a single crystal structure in the region near the surface. The two-dimensional growth of GaN extends laterally to form a planar two-dimensional continuous single-crystal GaN template layer. 5) Preparation of GaN single-crystal thin films: a) Two-dimensional materials with layered structures and disordered in-plane orientation are grown on a single-crystal GaN template layer using CVD; b) Using the second patterned mask as a mask, etch away the two-dimensional material above the first region, while retaining the two-dimensional material above the second region; c) GaN is grown using a lateral epitaxial method. GaN is grown on a single-crystal GaN template layer exposed above the first region and gradually expands to cover the second region. Dislocation turning and annihilation are induced by stretching the lattice through lateral epitaxy, thereby reducing the dislocation density and obtaining a GaN single-crystal thin film with a smooth surface and low dislocation density.

[0005] After obtaining a GaN single-crystal thin film with a smooth surface and low dislocation density, quantum structures for light-emitting devices or heterojunction structures for electronic devices are selectively prepared.

[0006] In step 1)a), sapphire is used as the growth substrate. A flat growth substrate refers to a (0001) oriented growth substrate with a surface roughness not exceeding 0.5 nm and a diameter of 2–8 inches. The transition metal chalcogenide is one of highly oriented molybdenum disulfide (MoS2), MoSe2, MoTe2, WS2, WSe2, WTe2, ReS2, ReSe2, and ReTe2, and the growth method is chemical vapor deposition (CVD) or metal-organic chemical vapor deposition (MOCVD), with a thickness of 3–30 atomic layers.

[0007] In step 1)b), the first single-crystal AlN thin film is grown by physical vapor deposition, molecular beam epitaxy or magnetron sputtering, with a growth temperature between 300 and 900°C, a growth rate between 1 nm / min and 20 nm / min, and a thickness between 20 nm and 500 nm.

[0008] In step 1), d), the functional substrate is made of polycrystalline diamond or boron arsenide, with a lattice structure and high thermal conductivity. A flat functional substrate refers to a substrate with a surface roughness not exceeding 2 nm. A long-range ordered lattice structure means that when the electron beam is incident along the <10-10> and <11-20> crystal phases using a high-energy reflection electron diffractometer, diffraction fringes characteristic of a single crystal can be observed. The thickness of the crystal orientation transition layer is 2-30 atoms, and the crystal orientation transition layer uses highly oriented graphene or boron nitride to adjust the crystal orientation.

[0009] In step 1) e), the growth conditions for growing the second single-crystal AlN film are the same as those for growing the first single-crystal AlN film in step 1) b).

[0010] In step 2)a), a high-temperature ammonia atmosphere treatment is performed in the metal-organic chemical vapor deposition system, with an ammonia flow rate between 0.01 SLM and 1 SLM, a nitrogen flow rate between 0.1 SLM and 10 SLM, an ambient vacuum degree between 10 and 1000 mbar, and a temperature between 20 and 600 °C. If the temperature is too high, the transition metal chalcogenide compounds will decompose.

[0011] In step 2)b), the size of the mask is the same as that of the flat growth substrate, i.e., between 2 and 8 inches, and both have the same reference edge setting. The two are aligned by aligning the reference edges. The circular holes of the mask penetrate from one side of the mask to the other side, with a diameter of 20 to 500 μm, and the distance between adjacent circular holes is 50 to 500 μm.

[0012] In step 3)a), the thermal conductivity extension material is multilayer graphene or boron nitride (BN). When preparing multilayer graphene or boron nitride by chemical vapor deposition (CVD), due to the lack of catalysis on the growth substrate, the migration ability of reactant atoms on the non-metallic surfaces such as the first AlN film and the functional substrate is insufficient when the growth temperature is in the range of 800–1100 °C. This results in the film structure formed by multilayer graphene or boron nitride being composed of randomly distributed in-plane oriented crystal domains. The growth time is controlled to keep its thickness approximately 5–20 atomic layers.

[0013] In step 4), during metal-organic chemical vapor deposition, the thickness of the three-dimensional GaN growth is between 50 and 1000 nm, the growth temperature is between 950 and 1050 °C, the working pressure is between 400 and 600 Torr, and the V / III ratio is between 4000 and 7000. At this point, the in-plane migration ability of metal atoms is insufficient, resulting in a lower lateral growth rate than longitudinal growth rate of GaN. Consequently, the three-dimensional GaN acts as a dislocation annihilation layer, forming a rough morphology composed of discontinuous GaN islands with high aspect ratios. The transition region from three-dimensional to two-dimensional growth uses the same growth parameters as the two-dimensional growth. The thickness of the transition region from three-dimensional to two-dimensional growth is between 300 and 2000 nm, while the thickness of two-dimensional GaN is between 500 and 2000 nm. The growth temperature is between 1050 and 1200 °C, the working pressure is between 50 and 250 Torr, and the V / III ratio is between 1000 and 2500. At this point, the in-plane migration ability of metal atoms is enhanced, resulting in a higher lateral growth rate than longitudinal growth rate for GaN. This leads to a continuous, smooth, and flat morphology in two-dimensional GaN, with a dislocation density near the surface of 5 × 10⁻⁶. 8 cm -2 ~5×10 9 cm -2 between.

[0014] In step 5)a), the two-dimensional material is multilayer graphene or boron nitride (BN). Multilayer graphene or boron nitride is prepared using CVD at a growth temperature between 800 and 1100 °C, with a thickness of approximately 3 to 10 atomic layers.

[0015] In step 5)c), GaN is deposited using metal-organic chemical vapor deposition in a two-dimensional growth mode. The GaN thickness is between 500 and 2000 nm, the growth temperature is between 1050 and 1200 °C, the working pressure is between 50 and 250 Torr, the V / III ratio is between 1000 and 2500, and the dislocation density of GaN near the surface is 5 × 10⁻⁶. 7 cm -2 ~5×10 8 cm -2 between.

[0016] Another objective of this invention is to provide a heteroepitaxial GaN single-crystal thin film with high heat dissipation capability.

[0017] The high heat dissipation heteroepitaxial GaN single-crystal thin film of the present invention is prepared by the following method: a transition metal chalcogenide is grown on a growth substrate; a first single-crystal AlN thin film is grown on the transition metal chalcogenide, placed in water, and the first single-crystal AlN thin film / transition metal chalcogenide is peeled off from the growth substrate; a crystal orientation transition layer with a long-range ordered lattice structure is transferred on a functional substrate, and a second single-crystal AlN thin film is grown on the crystal orientation transition layer to form a support substrate; the bottom surface of the first single-crystal AlN thin film / transition metal chalcogenide is placed on the surface of the support substrate, and an AlN composite structure is formed by van der Waals forces; the AlN composite structure is treated in a high-temperature ammonia atmosphere to modify the transition metal chalcogenide, generating a bonding transition layer, and obtaining a modified AlN composite structure; a first patterned mask with a two-dimensional periodic array of circular holes is used. As a mask, the modified AlN composite structure is etched onto the surface of the functional substrate. The surface of the first unetched single-crystal AlN film is defined as the first region, and the etched functional substrate exposed is defined as the second region. A thermally conductive extension material is grown on the patterned AlN composite structure. The thermally conductive extension material grown above the first region is removed to obtain a thermally conductive extension layer that connects the first and second regions. GaN is grown on this layer, forming a three-dimensional GaN, a transition region from three-dimensional to two-dimensional growth, and a two-dimensional GaN, which serves as a single-crystal GaN template layer. A two-dimensional material is grown on the single-crystal GaN template layer, and the two-dimensional material above the first region is removed. GaN is grown by lateral epitaxy. The GaN grows on the single-crystal GaN template layer exposed above the first region and gradually expands to cover the second region, resulting in a GaN single-crystal film with a smooth surface and low dislocation density.

[0018] Advantages of this invention: This invention utilizes a patterned AlN composite structure with embedded vertical heat dissipation channels as a heterogeneous substrate, enabling the direct epitaxy of GaN single-crystal thin films with high heat dissipation capacity and low dislocation density on a high thermal conductivity functional substrate. This provides a material basis for addressing the heat dissipation bottleneck faced by high-performance GaN devices. Its core advantages lie in: employing van der Waals force integration and two-dimensional material-assisted modification techniques to achieve low-damage and high-strength bonding between the high-quality AlN template and the functional substrate, avoiding the high thermal resistance problem of traditional bonding interfaces; and simultaneously achieving effective control of GaN crystal quality and the construction of an ultra-efficient in-plane-vertical hybrid heat dissipation path through innovative patterned design and selective region epitaxy. This method is highly compatible with existing wide-bandgap semiconductor epitaxial growth, micro / nano fabrication, and device fabrication processes. The fabricated high-heat-dissipation capacity and low dislocation density provide a material platform for high-current-density driven laser diodes and high-power electronic devices, potentially improving their operational stability, reliability, and lifespan. It has broad application prospects in the development of high-power electronic devices for power management, electric vehicles, consumer electronics, and photovoltaic inverters. Attached Figure Description

[0019] Figure 1 A schematic diagram showing the preparation of the first single-crystal AlN thin film using the high heat dissipation heteroepitaxial GaN single-crystal thin film method according to the present invention; Figure 2 A schematic diagram showing the preparation of a second single-crystal AlN thin film using the high heat dissipation heteroepitaxial GaN single-crystal thin film method according to the present invention; Figure 3 A schematic diagram of an AlN composite structure obtained by the method for preparing a high heat dissipation heteroepitaxial GaN single crystal thin film according to the present invention; Figure 4 This is a schematic diagram of the bonding transition layer obtained after modification by the method for preparing high heat dissipation heteroepitaxial GaN single crystal thin films according to the present invention. Figure 5 This is a schematic diagram of a patterned AlN composite structure obtained by the method for preparing a high heat dissipation heteroepitaxial GaN single crystal thin film according to the present invention. Figure 6 This is a schematic diagram of the thermally conductive extended layer obtained by the method for preparing a high heat dissipation heteroepitaxial GaN single crystal thin film according to the present invention. Figure 7 This is a schematic diagram of the single-crystal GaN template layer obtained by the method for preparing a high-heat-dissipation heteroepitaxial GaN single-crystal thin film according to the present invention; Figure 8 This is a schematic diagram illustrating the preparation method of a heteroepitaxial GaN single-crystal thin film with high heat dissipation capability according to the present invention. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0021] The method for preparing a high heat dissipation heteroepitaxial GaN single crystal thin film in this embodiment includes the following steps: 1) Preparation of AlN composite structure: a) Using 5-inch sapphire as the growth substrate, CVD is used to grow 20 atomic-layer-thick MoS2 on the growth substrate to form a transition metal chalcogenide. b) A first single-crystal AlN film with a thickness of 300 nm was grown on a transition metal chalcogenide substrate using physical vapor deposition at a growth temperature of 600 °C and a growth rate of 10 nm / min. Figure 1 As shown; c) Place the above structure in water and use the capillary action of water molecules to break the interfacial adsorption between the transition metal chalcogenide and the growth substrate, completely peel off the first single crystal AlN film / transition metal chalcogenide from the growth substrate, and let it float on the water surface completely under the action of buoyancy and tension. d) Using diamond as a functional substrate, a 20-atom-thick graphene with a long-range ordered lattice structure is transferred on the functional substrate as a crystal orientation transition layer. e) Using the same growth conditions as in step 1)b) on the first single-crystal AlN film, a continuous and flat second single-crystal AlN film is grown on the crystal orientation transition layer. The functional substrate, the crystal orientation transition layer, and the second single-crystal AlN film form a supporting substrate, such as... Figure 2 As shown; f) The first layer of single-crystal AlN film / transition metal chalcogenide floating on the water surface is retrieved and dried in air. The bottom surface of the first layer of single-crystal AlN film / transition metal chalcogenide is then tightly bonded to the surface of the substrate using van der Waals forces, forming an AlN composite structure of first layer single-crystal AlN film / transition metal chalcogenide / second layer single-crystal AlN film / crystal orientation transition layer / functional substrate, as shown below. Figure 3 As shown, it is used to adjust the crystal orientation; 2) Modification and graphical representation of AlN composite structures: a) The AlN composite structure was treated in a high-temperature ammonia atmosphere with an ammonia flow rate of 0.5 SLM, a nitrogen flow rate of 5 SLM, an ambient vacuum of 500 mbar, and a temperature of 300 °C. The nitrogen atoms in the ammonia replaced the sulfur atoms in the transition metal chalcogenide, modifying the layered structure of the transition metal chalcogenide and generating molybdenum nitride (MoN) with interlayer covalent bonds as a bonding transition layer, resulting in the modified AlN composite structure, as shown below. Figure 4 As shown; b) A 5-inch mask is processed using laser etching to form a two-dimensional periodic array of circular holes with a diameter of 300 μm and a distance of 300 μm between adjacent holes, thus obtaining the first patterned mask. c) Using the first patterned mask as a mask, the modified AlN composite structure is etched down to the surface of the functional substrate via ICP. A two-dimensional, periodically arranged array of circular holes is etched into the modified AlN composite structure. The unetched surface of the first single-crystal AlN thin film is defined as the first region, and the etched functional substrate surface is defined as the second region. The etched regions correspond one-to-one with the circular hole array of the first patterned mask, i.e., they have the same diameter, thus obtaining a patterned AlN composite structure. Figure 5 As shown, this is done to achieve stress relief, so that the regenerated long film does not crack; 3) Fabrication of the thermally conductive extension layer: a) A multilayer graphene with a layered structure and disordered in-plane orientation of 10 atomic layers was grown on a patterned AlN composite structure by chemical vapor deposition (CVD) to cover a first region with low thermal conductivity, a second region with high thermal conductivity, and a sidewall connecting the first and second regions. b) Using a second patterned mask complementary to the pattern of the first patterned mask, the multilayer graphene grown above the first region is etched away, retaining the second region and the multilayer graphene on the sidewalls connecting the first and second regions. The multilayer graphene has high in-plane thermal conductivity, and by connecting the low thermal conductivity first region with the high thermal conductivity second region through sidewall interconnection, a thermally conductive extended layer is obtained, such as... Figure 6 As shown, the thermal conductivity extension layer introduces new thermal conduction channels, avoiding the thermal conduction limitation problem introduced by the first single-crystal AlN film / bonding transition layer / second single-crystal AlN film in the vertical direction, thereby improving the thermal conductivity of the entire structure; 4) Preparation of single-crystal GaN template layer: GaN was grown on a patterned AlN composite structure with a thermally conductive extended layer using metal-organic chemical vapor deposition (MOCVD). The specific process involved altering the GaN growth mode by changing the growth temperature, V / III ratio, and growth pressure, resulting in three-dimensional GaN growth, a transition region from three-dimensional to two-dimensional growth, and finally, two-dimensional GaN growth. The three-dimensional GaN growth was 500 nm thick, at a growth temperature of 1000 °C, a working pressure of 500 Torr, and a V / III ratio of 6000. Because the second region exposed a functional substrate with thermally conductive extended material, GaN nucleation and growth were suppressed, resulting in low nucleation density, random in-plane orientation, and slow growth rate of the nucleated GaN. The first region exposed a first single-crystal AlN film. Since GaN and AlN both belong to the nitride semiconductor material system, GaN nucleation density was high, and the nucleated GaN shared the same properties as the underlying first single-crystal AlN film. The crystal orientation of GaN, i.e., GaN has a single-crystal structure, and due to the absence of high-index crystal planes exposed at its edges, its growth rate is fast; that is, GaN grows in the first region. As growth progresses, in the two stages of three-dimensional growth and the transition region from three-dimensional to two-dimensional growth, the lateral and longitudinal growth rates of the single-crystal GaN component above the first region are higher than those in the second region where high-index crystal planes are exposed. The thickness of the transition region from three-dimensional to two-dimensional growth is 1000 nm. The growth temperature of the two-dimensional GaN is 1100℃, the working pressure is 150 Torr, and the V / III ratio is 2000. This results in the single-crystal GaN component above the first region encapsulating and burying the second region after entering the two-dimensional growth mode, giving the two-dimensional GaN a single-crystal structure. In other words, the two-dimensional GaN near the surface is a single-crystal structure. The thickness of the two-dimensional GaN is 1000 nm. The lateral expansion of the two-dimensional GaN growth forms a planar, two-dimensional, continuous single-crystal GaN template layer, such as... Figure 7 As shown, the dislocation density near the surface of two-dimensionally grown GaN is 3 × 10⁻⁶. 9 cm -2 ; 5) Preparation of GaN single-crystal thin films: a) Using CVD at a growth temperature of 950℃, multilayer graphene with a layered structure and disordered in-plane orientation was grown on a single-crystal GaN template layer, with a thickness of 8 atomic layers. b) Using the second patterned mask as a mask, etch away the multilayer graphene grown above the first region, while retaining the multilayer graphene above the second region. c) Using a lateral epitaxial growth method, with a growth temperature of 1100℃, a working pressure of 100 Torr, and a V / III ratio of 1500, GaN is grown on a single-crystal GaN template layer exposed above the first region and gradually extends to cover the second region, resulting in a GaN single-crystal thin film, as shown below. Figure 8As shown, the thickness is 1500 nm; dislocation turning and annihilation are induced by lateral epitaxial lattice stretching. X-ray diffraction tests revealed that the full width at half maximum (FWHM) of the GaN (002) and (102) crystal planes are approximately 200 arcsec and 200 arcsec, respectively, corresponding to a dislocation density of approximately 3 × 10⁻⁶. 8 cm -2 Atomic force microscopy revealed that the surface roughness of a 10 μm × 10 region was approximately 0.3 nm, indicating that the obtained GaN single crystal film had a smooth surface and low dislocation density.

[0022] Finally, it should be noted that the purpose of disclosing the embodiments is to help further understand the present invention. However, those skilled in the art will understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the scope of protection of the present invention is defined by the claims.

Claims

1. A method for preparing a heteroepitaxial GaN single-crystal thin film with high heat dissipation capability, characterized in that, The preparation method includes the following steps: 1) Preparation of AlN composite structure: a) Growth of transition metal chalcogenides on a growth substrate; b) Growing the first single-crystal AlN thin film on a transition metal chalcogenide; c) Place the above structure in water and peel off the first single-crystal AlN film / transition metal chalcogenide from the growth substrate; d) Transfer the crystal orientation transition layer onto the functional substrate; e) A second single-crystal AlN film is grown on the crystal orientation transition layer, and the functional substrate, the crystal orientation transition layer and the second single-crystal AlN film form a support substrate. f) The bottom surface of the first single-crystal AlN thin film / transition metal chalcogenide is tightly bonded to the surface of the supporting substrate by van der Waals forces to obtain an AlN composite structure; 2) Modification and graphical representation of AlN composite structures: a) The AlN composite structure is treated with a high-temperature ammonia atmosphere to modify the transition metal chalcogenide and generate a bonded transition layer, thus obtaining the modified AlN composite structure. b) Prepare a first patterned mask with a two-dimensional periodic array of circular holes; c) Using the first patterned mask as a mask, the modified AlN composite structure is etched onto the surface of the functional substrate. The surface of the first single-crystal AlN thin film that is not etched is defined as the first region, and the functional substrate whose surface is etched and exposed is defined as the second region, thus obtaining the patterned AlN composite structure. 3) Fabrication of the thermally conductive extension layer: a) Growing thermally conductive extended materials on patterned AlN composite structures; b) Using a second patterned mask that is complementary to the pattern of the first patterned mask as a mask, the thermally conductive extended material grown above the first region is etched away to obtain a thermally conductive extended layer; 4) Preparation of single-crystal GaN template layer: GaN is grown on a patterned AlN composite structure with a thermally conductive extended layer. By controlling the growth conditions, the GaN undergoes a process of three-dimensional growth, a transition region from three-dimensional to two-dimensional growth, and two-dimensional growth. The two-dimensional GaN has a single-crystal structure, resulting in a single-crystal GaN template layer. 5) Preparation of GaN single-crystal thin films: a) Growing two-dimensional materials on a single-crystal GaN template layer; b) Using the second patterned mask as a mask, etch away the two-dimensional material above the first region, while retaining the two-dimensional material above the second region; c) GaN is grown using a lateral epitaxial growth method. GaN is grown on a single-crystal GaN template layer exposed above the first region and gradually extends to cover the second region, resulting in a GaN single-crystal thin film.

2. The preparation method according to claim 1, characterized in that, In step 1)a), the transition metal chalcogenide is one of MoS2, MoSe2, MoTe2, WS2, WSe2, WTe2, ReS2, ReSe2 and ReTe2, and the growth method is chemical vapor deposition or metal-organic chemical vapor deposition, with a thickness of 3 to 30 atomic layers.

3. The preparation method according to claim 1, characterized in that, In step 1)b), the first single-crystal AlN thin film is grown by physical vapor deposition, molecular beam epitaxy or magnetron sputtering, with a growth temperature between 300 and 900°C, a growth rate between 1 nm / min and 20 nm / min, and a thickness between 20 nm and 500 nm.

4. The preparation method according to claim 1, characterized in that, In step 1), d), the functional substrate is made of diamond or boron arsenic; the crystal orientation transition layer is made of graphene or boron nitride, and the thickness of the crystal orientation transition layer is 2 to 30 atoms.

5. The preparation method according to claim 1, characterized in that, In step 2)a), a high-temperature ammonia atmosphere treatment is performed in a metal-organic chemical vapor deposition system, with an ammonia flow rate between 0.01 SLM and 1 SLM, a nitrogen flow rate between 0.1 SLM and 10 SLM, an ambient vacuum degree between 10 and 1000 mbar, and a temperature between 20 and 600 °C.

6. The preparation method according to claim 1, characterized in that, In step 3)a), the thermal conductivity extension material is multilayer graphene or boron nitride; the thickness of the thermal conductivity extension material is 5 to 20 atomic layers.

7. The preparation method according to claim 1, characterized in that, In step 4), metal-organic chemical vapor deposition is used. The thickness of the three-dimensional GaN growth is between 50 and 1000 nm, the growth temperature is between 950 and 1050 °C, the working pressure is between 400 and 600 Torr, and the V / III ratio is between 4000 and 7000. The thickness of the transition region from three-dimensional to two-dimensional growth is between 300 and 2000 nm. The thickness of the two-dimensional GaN growth is between 500 and 2000 nm, the growth temperature is between 1050 and 1200 °C, the working pressure is between 50 and 250 Torr, and the V / III ratio is between 1000 and 2500.

8. The preparation method according to claim 1, characterized in that, In step 5)a), a two-dimensional material is deposited by chemical vapor deposition. The two-dimensional material is multilayer graphene or boron nitride. The growth temperature is in the range of 800~1100℃ and the thickness is 3~10 atomic layers.

9. The preparation method according to claim 1, characterized in that, In step 5)c), GaN is deposited using metal-organic chemical vapor deposition. The GaN thickness is between 500 and 2000 nm, the growth temperature is between 1050 and 1200 °C, the working pressure is between 50 and 250 Torr, and the V / III ratio is between 1000 and 2500.

10. A heteroepitaxial GaN single-crystal thin film with high heat dissipation capability obtained by the preparation method according to claim 1, characterized in that, The GaN single-crystal thin film is prepared by the following method: a transition metal chalcogenide is grown on a growth substrate; a first single-crystal AlN thin film is grown on the transition metal chalcogenide, placed in water, and the first single-crystal AlN thin film / transition metal chalcogenide is peeled off from the growth substrate; a crystal orientation transition layer with a long-range ordered lattice structure is transferred on a functional substrate, and a second single-crystal AlN thin film is grown on the crystal orientation transition layer to form a support substrate; the bottom surface of the first single-crystal AlN thin film / transition metal chalcogenide is placed on the surface of the support substrate, and an AlN composite structure is formed by van der Waals forces; the AlN composite structure is treated in a high-temperature ammonia atmosphere to modify the transition metal chalcogenide, generating a bonded transition layer, and obtaining the modified AlN. An AlN composite structure is constructed. A patterned mask with a two-dimensional periodic array of circular holes is used as a mask to etch the modified AlN composite structure onto the surface of a functional substrate. The unetched surface of the first single-crystal AlN film is defined as the first region, and the etched functional substrate surface is defined as the second region. A thermally conductive extension material is grown on the patterned AlN composite structure. The thermally conductive extension material grown above the first region is removed, resulting in a thermally conductive extension layer connecting the first and second regions. GaN is grown on this layer, sequentially forming a three-dimensional GaN, a transition region from three-dimensional to two-dimensional growth, and a two-dimensional GaN, serving as a single-crystal GaN template layer. A two-dimensional material is grown on the single-crystal GaN template layer, and the two-dimensional material above the first region is removed. GaN is grown by a lateral epitaxial method. GaN grows on a single-crystal GaN template layer exposed above the first region and gradually expands to cover the second region, thus obtaining a GaN single-crystal thin film.

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