Hetero semiconductor structure and method of manufacturing the same

Abstract

The present application discloses a hetero-semiconductor structure and a method for manufacturing the same. The method comprises forming a first epitaxial film composed of three-dimensional semiconductor material on a substrate by epitaxy in a vacuum condition; and forming a second epitaxial film composed of two-dimensional semiconductor material on the first epitaxial film by epitaxy in the vacuum condition. The substrate is an oxide single crystal substrate, the three-dimensional semiconductor material is N-type semiconductor material with three-dimensional crystal structure, and the two-dimensional semiconductor material is P-type semiconductor material with multi-layered layered crystal structure. Thus, the cleanliness and epitaxial quality of the interface between the two-dimensional and three-dimensional materials in the hetero-semiconductor structure are effectively improved.

Description

Technical Field

[0001] This invention relates to a semiconductor structure, and more particularly to a heterogeneous semiconductor structure suitable for optical applications and a method for manufacturing the same. Background Technology

[0002] In the field of heterogeneous semiconductor technology, integrating semiconductor materials of different types or different lattice structures into a single component has the potential to realize applications in optoelectronic devices (such as photodetectors). However, in existing technologies, lattice mismatches between heterogeneous materials or poor epitaxial quality often lead to interface defects during epitaxial growth, such as interlayer dislocations, voids, interface discontinuities, or chemical contamination. These defects subsequently affect the carrier migration efficiency, interface stability, and overall performance of the device. Especially in heteroepitaxial growth, controlling interface quality remains a technical challenge. The industry still has a strong demand for high-quality, reproducible, and scalable heterosemiconductor structures. Summary of the Invention

[0003] This invention discloses a heterogeneous semiconductor structure suitable for optical applications and its manufacturing method, mainly to improve the problems existing in the prior art.

[0004] This invention discloses a method for manufacturing a heterogeneous semiconductor structure, comprising: performing a first epitaxial operation, including: using a vacuum epitaxial system at a depth between 10... -12 Torr to 10 -7 Under a vacuum condition, a first epitaxial film composed of a three-dimensional semiconductor material is epitaxially formed on a substrate; wherein the substrate is an oxide single-crystal substrate, and the three-dimensional semiconductor material is an N-type semiconductor material having a three-dimensional crystal structure; and a second epitaxial operation is performed, comprising: in the vacuum epitaxial system, under the condition of maintaining and not breaking the vacuum, epitaxially forming a second epitaxial film composed of a two-dimensional semiconductor material on the first epitaxial film; wherein the two-dimensional semiconductor material is a P-type semiconductor material having a multilayered crystal structure.

[0005] Optionally, the vacuum epitaxy system is a molecular beam epitaxy system, and the vacuum conditions are between 10... -11 Torr to 10 -9 Torr.

[0006] Optionally, the oxide single-crystal substrate is a sapphire single-crystal substrate, and the three-dimensional semiconductor material has a first bandgap between 4.8 eV and 5.0 eV and an in-plane lattice constant between 2.8 Å and 3.3 Å in the b-axis direction; wherein the two-dimensional semiconductor material has a second bandgap between 1.9 eV and 2.1 eV, and the relative difference between the in-plane lattice constants of the two-dimensional semiconductor material and the three-dimensional semiconductor material is not greater than 25%. Optionally, the manufacturing method further includes: a surface pretreatment operation performed between the first epitaxial operation and the second epitaxial operation; wherein the surface pretreatment operation includes: after the first epitaxial operation, performing a vapor deposition pretreatment on the first epitaxial film formed on the substrate using a metal source to form a metal termination layer on the surface of the first epitaxial film.

[0007] Optionally, the metal atoms in the vapor deposition pretreatment are the same as at least one metal element in the three-dimensional semiconductor material; wherein the metal atoms in the vapor deposition pretreatment form bonds with the oxygen element of the three-dimensional semiconductor material to form the metal terminal layer.

[0008] Optionally, the second epitaxial operation is performed after the surface pretreatment operation, which includes further forming the second epitaxial film on the metal terminal layer on the first epitaxial film, and forming a non-metallic passivation layer between the interface of the first epitaxial film and the second epitaxial film.

[0009] Optionally, the three-dimensional semiconductor material of the first epitaxial thin film is β-gallium oxide (β-Ga2O3); the metal atom in the evaporation pretreatment is gallium (Ga); the two-dimensional semiconductor material of the second epitaxial thin film is gallium selenide (GaSe), and the non-metallic element in the non-metallic passivation layer is selenium (Se).

[0010] Optionally, the first epitaxial operation includes heating the substrate to a first epitaxial temperature between 400°C and 500°C.

[0011] Optionally, the first epitaxial operation further includes: oxygen activation using a radio frequency oxygen plasma source of the vacuum epitaxial system, with a radio frequency power of 250 W to 350 W, an oxygen gas flow rate of 0.5 sccm to 2 sccm, a gallium atom source as the metal source, and a metal atom flux of 1.0 × 10⁻⁶. -8 Torr up to 5.0×10 -8 The first epitaxial film is formed under conditions of Torr and epitaxial time of 30 to 120 minutes; wherein the surface roughness (RMSroughness) of the first epitaxial film is not greater than 1 nm.

[0012] Optionally, in the surface pretreatment operation, the vapor deposition pretreatment first heats the substrate to a vapor deposition temperature of 380°C to 460°C; then the metal source is turned on to perform atomic pre-vapor deposition for 1 to 10 minutes to form the metal terminal layer.

[0013] Optionally, the metal source flux in the vapor deposition pretreatment is between 1.0 × 10⁻⁶. -8 Up to 8.0×10 -8 Torr, wherein the metal atoms used in the metal source are the same as the metal elements of the three-dimensional semiconductor material; the surface pretreatment operation is followed by raising the substrate temperature from the evaporation temperature to an annealing temperature of 550°C to 650°C, maintaining it for 5 to 15 minutes, and then cooling it down to form the metal terminal layer.

[0014] Optionally, the second epitaxial operation adjusts the substrate to a second epitaxial temperature between 410°C and 440°C; subsequently, a metal source and a non-metal source in the vacuum epitaxial system are turned on to perform epitaxy and form the second epitaxial film.

[0015] Optionally, the metal source flux ranges from 2.0 × 10⁻⁶. -8 Torr up to 8.0×10 -8 Torr, the nonmetallic source flux ranges from 2.0 × 10⁻⁶. -7 Torr up to 8.0×10 -7 Torr, and the flux ratio between the non-metal source and the metal source is between 8 and 15; wherein the metal source is a gallium atom beam source, the non-metal source is a selenium atom beam source, and the epitaxial time of the second epitaxial operation is between 30 minutes and 120 minutes.

[0016] Optionally, during the second epitaxial operation, real-time monitoring by high-energy reflected electron diffraction (RHEED) shows that the nucleation delay time during the growth of the second epitaxial thin film is less than 3 minutes.

[0017] This invention also discloses a heterogeneous semiconductor structure, comprising: a substrate; wherein the substrate is an oxide single-crystal substrate; a first epitaxial thin film formed on the substrate and composed of a three-dimensional semiconductor material; wherein the three-dimensional semiconductor material is an N-type semiconductor material with a three-dimensional crystal structure; and a second epitaxial thin film formed on the first epitaxial thin film and composed of a two-dimensional semiconductor material; wherein the two-dimensional semiconductor material is a P-type semiconductor material with a multilayered crystal structure.

[0018] Optionally, the oxide single-crystal substrate is a sapphire single-crystal substrate, and the three-dimensional semiconductor material has a first bandgap between 4.8 eV and 5.0 eV and an in-plane lattice constant between 2.8 Å and 3.3 Å in the b-axis direction; wherein the two-dimensional semiconductor material has a second bandgap between 1.9 eV and 2.1 eV, and the relative difference between the in-plane lattice constants of the two-dimensional semiconductor material and the three-dimensional semiconductor material is not greater than 25%.

[0019] Optionally, the heterogeneous semiconductor structure further includes: a metal termination layer formed between the first epitaxial thin film and the second epitaxial thin film; and a non-metal passivation layer formed between the first epitaxial thin film and the second epitaxial thin film; wherein the metal termination layer is formed on the first epitaxial thin film, and the non-metal passivation layer is formed on the metal termination layer and located below the second epitaxial thin film; wherein the metal atoms of the metal termination layer are the same as the metal elements of the three-dimensional semiconductor material, and the non-metal elements of the non-metal passivation layer are the same as the non-metal elements of the two-dimensional semiconductor material.

[0020] Optionally, the first epitaxial film has a thickness of 20 nanometers to 50 nanometers, the second epitaxial film is formed by stacking multiple two-dimensional structural units with a total thickness of between 50 nanometers and 120 nanometers, the thickness of each two-dimensional structural unit is between 0.50 nanometers and 1.0 nanometers, and the thickness of the non-metallic passivation layer is between 0.3 nanometers and 1.0 nanometers.

[0021] In summary, the heterogeneous semiconductor structure and its manufacturing method for optical applications disclosed in the embodiments of this invention can effectively improve the cleanliness and epitaxial quality of the interface between two-dimensional and three-dimensional materials in the heterogeneous semiconductor structure through the above-mentioned technical solutions. Compared with traditional transfer or peel-off stacking methods, this invention can significantly reduce the interface defect density and enhance the integrity of the heterogeneous structure bonding. In addition, this invention can achieve high-quality heterojunction structures, which have excellent electrical stability and response performance for subsequent optoelectronic component applications (such as self-powered photodetectors).

[0022] To further understand the features and technical content of this invention, please refer to the following detailed description and accompanying drawings. However, these descriptions and drawings are only for illustrating the invention and are not intended to limit the scope of protection of the invention in any way. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the manufacturing process of the first embodiment of the present invention. Figure 2A This is a schematic diagram of the formation of the first epitaxial layer in the first embodiment of the present invention. Figure 2BThis is a schematic diagram of the formation of the second epitaxial layer in the first embodiment of the present invention. Figure 3 This is a schematic diagram of the manufacturing process of the second embodiment of the present invention. Figure 4A This is a schematic diagram of the metal terminal layer formed according to the second embodiment of the present invention. Figure 4B This is a schematic diagram of the formation of a non-metallic passivation layer according to the second embodiment of the present invention. Figure 5A This is a schematic diagram of a heterogeneous semiconductor structure according to a second embodiment of the present invention. Figure 5B for Figure 5A A magnified view of a portion of region VB. Figure 6 The results of in-situ high-energy electron diffraction (IHEED) analysis in this embodiment of the invention are for samples S1 to S3. Figure 7 The results of photoluminescence (PL) analysis in this embodiment of the invention are for samples S1 to S3. Figure 8 This is an analytical image (for sample S3) obtained by high-resolution transmission electron microscopy (HRTEM) of a heterosemiconductor structure according to an embodiment of the present invention. Figure 9 for Figure 8 A high-magnification image of a heterogeneous semiconductor structure. Detailed Implementation In the following description, if a specific drawing is indicated or shown in a specific drawing, it is only to emphasize that most of the relevant content mentioned in the following description appears in that specific drawing, but does not limit the following description to refer only to that specific drawing.

[0024] This invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of this invention.

[0025] It should be understood that although terms such as "first," "second," and "third" may be used in this article to describe various materials or parameters, these materials or parameters should not be limited by these terms. These terms are mainly used to distinguish one material from another, or one parameter from another.

[0026] Additionally, the term "or" as used in this document should be interpreted as including, depending on the context, any combination of one or more of the related listed items.

[0027] [First Embodiment] Please see Figure 1, Figure 2A and Figure 2B As shown, the first embodiment of the present invention provides a method for manufacturing a heterogeneous semiconductor structure, including step S110 (first epitaxial operation) and step S120 (second epitaxial operation).

[0028] [First Extension Task] like Figure 2A As shown, step S110 is to perform a first epitaxial operation, which includes: using a vacuum epitaxial system E under vacuum conditions to epitaxially form a first epitaxial thin film 1 made of a three-dimensional semiconductor material on a substrate S. The vacuum epitaxial system E can be, for example, a molecular beam epitaxy (MBE) system. More specifically, the vacuum epitaxial system E is a system used for the epitaxy of semiconductor materials, which deposits atoms or molecules onto the surface of a substrate in an ultra-high vacuum environment to form an epitaxial thin film.

[0029] In some embodiments, the vacuum conditions are achieved within the vacuum chamber E1 of the vacuum epitaxial system E. The operating pressure range of the vacuum conditions may be between approximately 10... -12 Torr to 10 -7 Torr, preferably between 10 -11 Torr to 10 - 8 Torr, and the preferred option is between 10 -11 Torr to 10 -9 Torr.

[0030] In some embodiments, the substrate S is an electrically insulating single crystal substrate. Optionally, the substrate S is a sapphire single crystal substrate (e.g., a c-plane sapphire substrate). The sapphire single crystal substrate is formed of single crystal alumina (α-Al₂O₃), but the invention is not limited thereto. The substrate S may also be other oxide single crystal substrates, such as strontium titanate (SrTiO₃) single crystal substrates, lanthanum aluminate (LaAlO₃) single crystal substrates, or magnesium oxide (MgO) single crystal substrates.

[0031] The three-dimensional semiconductor material is an N-type semiconductor material with a three-dimensional crystal structure (i.e., a semiconductor material that inherently or after doping exhibits N-type conductivity). The three-dimensional semiconductor material can be a three-dimensional carrier layer in a heterogeneous semiconductor structure, possessing high collapse electric field, high thermal stability, and the ability to form semiconductor heterojunctions with two-dimensional materials.

[0032] In this embodiment, the three-dimensional semiconductor material is gallium oxide (Ga2O3), particularly n-type β-gallium oxide (n-type β-Ga2O3), but is not limited thereto. The three-dimensional N-type semiconductor material can also be other suitable metal oxides, such as indium oxide (In2O3) or zinc oxide (ZnO).

[0033] In terms of physical properties, the three-dimensional semiconductor material has a first bandgap between 2.8 eV and 5.0 eV, and more preferably between 4.8 eV and 5.0 eV, and the first in-plane lattice constant (b-axis direction) of the three-dimensional semiconductor material is between 2.8 Å and 3.3 Å.

[0034] [Second Extension Operation] like Figure 2B As shown, step S120 is to perform a second epitaxial operation, which includes: in the vacuum epitaxial system E, under the condition of maintaining the vacuum (without breaking the vacuum condition), epitaxially forming a second epitaxial film 2 made of two-dimensional semiconductor material on the first epitaxial film 1. In other words, the first epitaxial film 1 and the second epitaxial film 2 are formed sequentially in the vacuum cavity E1 of the same vacuum epitaxial system E (molecular beam epitaxy system) under conditions where the vacuum is not broken.

[0035] The two-dimensional semiconductor material is a P-type semiconductor material with a two-dimensional layered crystal structure. In other words, the second epitaxial thin film 2 is a multilayered structure formed by two-dimensional semiconductor material, each layer is formed by covalent bonds, and the layers are bonded together by van der Waals forces.

[0036] In some embodiments, the two-dimensional semiconductor material is gallium selenide (GaSe), particularly a layered gallium selenide structure that is inherently P-type conductive, exhibiting lattice matching when forming a heterojunction with the aforementioned three-dimensional semiconductor material. For example, the relative difference in in-plane lattice constants between GaSe (3.785 Å) and β-Ga₂O₃ (b≈3.04 Å) is less than 25%. Furthermore, the two-dimensional semiconductor material has a second bandgap between 1.9 eV and 2.1 eV, making it suitable for optoelectronic applications in the visible to near-infrared region.

[0037] In other embodiments, the two-dimensional semiconductor material may also be a layered semiconductor with properties similar to gallium selenide, such as molybdenum sulfide (MoS2), molybdenum selenide (MoSe2), molybdenum telluride (MoTe2); or tungsten sulfide (WS2), tungsten selenide (WSe2), tungsten telluride (WTe2).

[0038] The two-dimensional semiconductor materials mentioned above can be selected according to application requirements, and their number of layers, thickness and growth temperature can be further controlled to optimize carrier migration efficiency, band alignment and photoresponse characteristics in heterostructures.

[0039] [Second Embodiment] In the above embodiment, a first epitaxial film 1 and a second epitaxial film 2 are sequentially epitaxially formed on the substrate S through a first epitaxial operation (step S110) and a second epitaxial operation (step S120).

[0040] Please see Figure 3 , Figure 4A and Figure 4B As shown, a second embodiment of the present invention also provides a method for manufacturing a heterogeneous semiconductor structure, which includes a first epitaxial operation (step S110), a surface pretreatment operation (step S110a), and a second epitaxial operation (step S120). The main difference between the second embodiment and the first embodiment is that the manufacturing method of the second embodiment further includes a surface pretreatment operation (step S110a) performed between the first epitaxial operation (step S110) and the second epitaxial operation (step S120).

[0041] [Surface Pretreatment Operation] Specifically, such as Figure 4A The surface pretreatment operation includes: after the first epitaxial operation (step S110), performing atomic-level metal evaporation pretreatment on the first epitaxial thin film 1 formed on the substrate S using a metal source E2a to form a metal-terminated surface 1a on the surface of the first epitaxial thin film 1 to promote the nucleation and growth of the two-dimensional semiconductor material in the subsequent second epitaxial operation (step S120). That is, the metal-terminated surface 1a can change the surface free energy, shorten the subsequent nucleation delay of the two-dimensional semiconductor material, and suppress the generation of interface defects. It is worth mentioning that the surface pretreatment operation is also performed in the vacuum epitaxial system E, maintaining the vacuum conditions (without breaking the vacuum conditions).

[0042] The metal atoms in the atomic-level metal evaporation pretreatment are the same as or matched with at least one metal element in the three-dimensional semiconductor material (such as chemically compatible metal elements, such as gallium, indium, or aluminum). For example, when the three-dimensional semiconductor material of the first epitaxial thin film 1 is gallium oxide (Ga2O3), the metal atoms of the atomic-level metal evaporation pretreatment can be gallium (Ga), which can form bonds with the oxygen elements of the first epitaxial thin film 1 (capped oxygen defects) to form the metal-terminated surface of gallium, thereby promoting the subsequent nucleation and layered stacking of two-dimensional semiconductor materials.

[0043] In other embodiments, the metal atoms used in the atomic evaporation process may also be selected from elements that are the same as or chemically compatible with the main group metals of the three-dimensional semiconductor material, such as indium (In), aluminum (Al), or zinc (Zn), depending on the material system and interface engineering requirements.

[0044] Then, as Figure 4B The second epitaxial operation (step S120) involves further forming a second epitaxial film 2 composed of a two-dimensional semiconductor material on the metal termination layer 1a on the surface of the first epitaxial film 1. The two-dimensional semiconductor material reacts with the metal termination layer 1a to form a non-metal passivation layer 1b between the interface of the first epitaxial film 1 and the second epitaxial film 2. The non-metal passivation layer 1b is formed on the metal termination layer 1a.

[0045] The non-metallic elements in the non-metallic passivation layer 1b are the same as those in the two-dimensional semiconductor material.

[0046] For example, when the two-dimensional semiconductor material of the second epitaxial thin film 2 is gallium selenide (GaSe), the non-metallic element in the non-metallic passivation layer 1b is selenium (Se), which originates from the non-metallic elements in the two-dimensional semiconductor material. This non-metallic element can react with the metallic element of the metal terminal layer 1a on the surface of the first epitaxial thin film 1 (e.g., the reaction between selenium and gallium), thereby forming the non-metallic passivation layer (e.g., a selenium passivation layer). It is worth noting that during the epitaxial operation of the second epitaxial thin film 2 (e.g., GaSe), the flux of the non-metallic source E2b (e.g., a Se atom beam) is set much higher than the flux of the metallic source E2a (e.g., a Ga atom beam), forming a selenium-rich environment. This selenium-rich environment helps to increase the surface Se atom concentration, thereby promoting the reaction between Se and the surface of the metallic terminal layer 1a (e.g., Ga) to form a continuous and stable non-metallic passivation layer, improving the interface quality and epitaxial stability of the heterostructure.

[0047] The non-metallic passivation layer 1b has a single-layer or sub-single-layer thickness and exists between the first epitaxial film 1 and the second epitaxial film 2 in the form of van der Waals forces or weak bonds, which helps to maintain the interlayer stacking characteristics of the two-dimensional layered material and improve the stability of heteroepitaxial integration.

[0048] In other embodiments, when the two-dimensional semiconductor material of the second epitaxial thin film 2 is another layered semiconductor material with properties similar to gallium selenide, such as molybdenum sulfide, molybdenum selenide, molybdenum telluride, tungsten sulfide, tungsten selenide, or tungsten telluride, the non-metallic element in the non-metallic passivation layer 1b can correspond to the main group anionic element in the two-dimensional semiconductor material, for example as follows: the non-metallic element can be selenium (Se), sulfur (S), or tellurium (Te).

[0049] The aforementioned non-metallic elements can bond with the metallic elements (such as gallium) of the metal terminal layer 1a formed on the surface of the first epitaxial film 1 during the epitaxial process, forming a stable non-metallic passivation layer 1b, thereby promoting the bonding integrity of the heterojunction and reducing the interface defect density.

[0050] In other words, the non-metallic element can be an element of Group VIA of the periodic table, including but not limited to selenium (Se), sulfur (S), and tellurium (Te). It can form stable chemical bonds with the metal elements (such as Ga and In) of the metal terminal layer, which helps to construct a high-quality two-dimensional-three-dimensional hybrid heterostructure.

[0051] The above describes the procedures for the first epitaxial operation, the second epitaxial operation, and the surface pretreatment operation. The following sections will describe the procedure details and process conditions for each of these operations.

[0052] [Process details and technological conditions for the first epitaxial operation] Please continue reading. Figure 1 and Figure 2A As shown, the first epitaxial operation (step S110) is intended to epitaxially form a first epitaxial thin film 1 composed of a three-dimensional semiconductor material on the substrate S.

[0053] In some embodiments of the present invention, the first epitaxial operation is performed using a plasma-assisted molecular beam epitaxy (PA-MBE) system. This system has an ultra-high vacuum chamber (E1) to provide an atomically clean environment, the operating pressure of which can be between approximately 10... -11 Torr to approximately 10 -8 Torr, with a preferred range of approximately 10 -11 Torr to 10 -9Torr, and preferably about 10 -10 Torr. In the epitaxial process, the first epitaxial operation uses an electrically insulating single-crystal substrate, preferably a sapphire single-crystal substrate, with a chemical composition of single-crystal aluminum oxide (α-Al2O3). Alternatively, other insulating oxide single-crystal substrates with lattice matching with the subsequent three-dimensional semiconductor material can also be used, such as strontium titanate (SrTiO3) single-crystal substrates, lanthanum aluminate (LaAlO3) single-crystal substrates, or magnesium oxide (MgO) single-crystal substrates. In this embodiment, the first epitaxial thin film 1 is formed by epitaxy of a three-dimensional N-type semiconductor material, namely β-phase gallium oxide (β-Ga2O3), which has an ultrawide bandgap (about 4.8 to 5.0 eV), a high breakdown electric field, and high thermal stability, and is suitable as a substrate layer for subsequent epitaxial growth of two-dimensional semiconductor materials. The process conditions for the first epitaxial operation include: firstly, heating the substrate S to a first epitaxial temperature between approximately 400°C and approximately 500°C, preferably between approximately 425°C and 475°C, and particularly preferably 450°C. The ramp rate to the first epitaxial temperature is approximately 5°C / min to 20°C / min, preferably approximately 10°C / min. Next, oxygen activation is performed using a radio frequency (RF) oxygen plasma source of a molecular beam epitaxy system, with an RF power of approximately 250W to 350W, preferably approximately 300W, and an oxygen plasma flow rate of approximately 0.5 sccm to 2 sccm, preferably approximately 1 sccm. The metal source E2a of the vacuum epitaxial system E is a gallium (Ga) atom source, with a Ga flux ranging from approximately 1.0 × 10⁻⁶. -8 Torr up to 5.0×10 -8 Between Torr, approximately 2.0 × 10 is preferred. -8 Torr is used to control the thickness and composition of the film.

[0054] Under the above conditions, an epitaxial growth time of approximately 30 to 120 minutes, preferably 45 to 75 minutes, and particularly preferably 55 to 65 minutes (e.g., 60 minutes), can form a first epitaxial film 1 (e.g., a β-Ga2O3 film layer) on the surface of the substrate S, with a thickness of approximately 20 nm to 50 nm, preferably approximately 30 nm to 35 nm. Subsequently, the temperature is lowered to a first cooling temperature of 20°C to 80°C at a rate of 10°C / min to 30°C / min, preferably approximately 20°C / min. The epitaxy process is monitored in real-time by high-energy reflection electron diffraction (RHEED) using a vacuum epitaxial system E (e.g., PA-MBE), allowing for real-time assessment of epitaxial growth behavior and surface crystallization properties.

[0055] For example, the formed β-Ga2O3 thin film has a clear epitaxial orientation in the (201) crystal plane direction, and its in-plane lattice constant b-axis direction is about 2.8 Å to 3.3 Å, preferably about 3.0 Å to 3.1 Å, and particularly preferably about 3.04 Å; its surface roughness (RMS roughness) is less than 1 nm, preferably less than 0.8 nm, and particularly preferably about 0.56 nm.

[0056] The aforementioned first epitaxial process can effectively provide a three-dimensional N-type semiconductor substrate with atomic-level cleanliness, low defect density, high crystal quality, and stable surface properties, which is helpful for the subsequent nucleation, growth, and interface engineering of two-dimensional semiconductor materials to form a mixed-dimensional heterosemiconductor structure with excellent optoelectronic properties.

[0057] [Details of surface pretreatment procedures and process conditions] Please continue reading. Figure 3 , Figure 4A and Figure 4B As shown above, the method for manufacturing the heterogeneous semiconductor structure may selectively further perform a surface pretreatment operation (step S110a) between the first epitaxial operation (step S110) and the second epitaxial operation (step S120). Specifically, this surface pretreatment operation is performed in the vacuum chamber E1 of the vacuum epitaxial system E while maintaining the vacuum conditions (i.e., without breaking the vacuum environment).

[0058] The surface pretreatment process comprises two main steps: atomic metal vapor deposition (i.e., atomic-level metal vapor deposition pretreatment) and subsequent annealing. In the atomic metal vapor deposition step, the substrate S is first heated from the aforementioned first cooling temperature (e.g., 20°C to 80°C) to a vapor deposition temperature between approximately 380°C and approximately 460°C, preferably between approximately 400°C and approximately 450°C, and particularly preferably between approximately 420°C and approximately 430°C (e.g., 425°C). Then, the metal source E2a is turned on, and atomic vapor deposition is performed for approximately 1 to 10 minutes, preferably between approximately 3 to 7 minutes, and particularly preferably between approximately 4 to 6 minutes (e.g., 5 minutes). The flux of metal atoms (e.g., Ga flux) used in the atomic vapor deposition step is approximately 1.0 × 10⁻⁶. -8 Up to 8.0×10 -8 Between Torr, the preferred range is approximately 3.0 × 10. -8 Up to 6.0×10 -8 Torr, preferably approximately 4.0 × 10⁻⁶ -8 Up to 5.0×10 -8 Torr (e.g., 4.5 × 10) -8 Torr).

[0059] In the above-mentioned atomic evaporation process, the metal atoms used in the metal source E2a can be elements that are the same as or chemically compatible with at least one metal element of the three-dimensional semiconductor material, such as, but not limited to, gallium (Ga), indium (In), or aluminum (Al). For example, when the three-dimensional semiconductor material of the first epitaxial thin film 1 is gallium oxide (Ga2O3), the selected metal atom is gallium (Ga).

[0060] The substrate S is then subjected to an annealing process, wherein the temperature of the substrate S is increased from the vapor deposition temperature (e.g., about 425°C) at a rate of about 10°C / min to 20°C / min to an annealing temperature between about 550°C and 650°C, preferably between about 580°C and 620°C, and particularly preferably between about 600°C, and this annealing temperature is maintained for about 5 minutes to 15 minutes, preferably between about 8 minutes and 12 minutes (e.g., 10 minutes); then the substrate S is cooled from the annealing temperature to a second epitaxial temperature (e.g., about 425°C to 440°C) for the subsequent second epitaxial operation at a rate of about 10°C / min to 30°C / min.

[0061] Through this metal atom evaporation and subsequent annealing process, the surface of the first epitaxial film 1 can be effectively transformed from the original oxygen-terminated surface to the metal-terminated surface, forming a metal-terminated layer 1a. This transformation can be monitored in real time by high-energy reflection electron diffraction (RHEED) to observe the stripe pattern change from continuous to spotty pattern, accompanied by a slight change in spacing, confirming the occurrence of surface reconstruction and strain release. The formation of the metal terminal layer 1a can effectively change the surface free energy of the first epitaxial film 1, thereby improving the nucleation conditions of subsequent two-dimensional semiconductor materials on the surface and significantly shortening the nucleation delay. Experimental observations show that the nucleation delay of two-dimensional semiconductor materials (such as GaSe) on this surface after pretreatment can be significantly shortened from about 15 minutes to less than 1 minute; it can also improve the uniformity of nucleation, the uniformity of growth layer thickness, and the surface coverage of the subsequent second epitaxial film 2 (such as GaSe two-dimensional layered film), avoid interlayer dislocation, and thus ensure the structural quality and excellent optoelectronic properties of the heterostructure interface.

[0062] [Process details and conditions for the second epitaxial operation] Please continue reading. Figure 2B or Figure 4BAs shown, the second epitaxial operation (step S120) of the present invention aims to epitaxially form a second epitaxial film 2 made of two-dimensional semiconductor material on the first epitaxial film 1 to form a mixed-dimensional heterostructure.

[0063] In some embodiments of the present invention, the second epitaxial operation can be performed directly after the first epitaxial operation (as in the first embodiment described above). Figure 1 and Figure 2B Alternatively, as described above, a surface pretreatment operation can be selectively performed after the first epitaxial operation before proceeding (as in the second embodiment described above). Figure 3 and Figure 4B Regardless of whether the aforementioned surface pretreatment is performed, the second epitaxial operation is carried out within the vacuum chamber E1 of the same vacuum epitaxial system E, continuously maintaining the ultra-high vacuum conditions (without breaking the vacuum environment).

[0064] In the second epitaxial operation, the substrate S is heated from the first cooling temperature (e.g., 20°C to 80°C) to a second epitaxial temperature between approximately 410°C and 490°C (i.e., the second epitaxial operation in the first embodiment is performed directly after the first epitaxial operation), preferably in the range of approximately 410°C to 440°C, particularly preferably approximately 425°C, with a heating rate of approximately 5°C / min to 20°C / min, preferably in the range of approximately 8°C / min to 15°C / min, particularly preferably approximately 10°C / min; or cooled from the annealing temperature (e.g., 550°C to 650°C) to the second epitaxial temperature (i.e., the second epitaxial operation in the second embodiment is performed after the surface pretreatment operation), with a cooling rate of approximately 10°C / min to 30°C / min. The aforementioned second epitaxial temperature condition is based on effectively suppressing the formation of impurity phases (such as Ga2Se3 impurity phases) to ensure a high-purity phase structure of the second epitaxial film 2 (such as a GaSe two-dimensional layered film). A second epitaxial temperature range of approximately 410°C to 440°C provides better suppression of impurity phase formation. Conversely, higher temperatures (such as above 480°C) may lead to a longer nucleation delay.

[0065] In the second epitaxial operation, when the substrate S temperature reaches the second epitaxial temperature (e.g., 425°C to 440°C), the metal source E2a (e.g., a gallium (Ga) atomic beam source) and the non-metal source E2b (e.g., a selenium (Se) atomic beam source) of the molecular beam epitaxy system are successively turned on to perform the epitaxial operation, wherein the flux of the metal source E2a is approximately 2.0 × 10⁻⁶. -8 Torr up to 8.0×10 -8 Between Torr, the preferred range is approximately 3.0 × 10. -8 Torr up to 6.0×10-8 Torr, preferably approximately 4.5 × 10⁻⁶ -8 Torr. The E2b flux of the nonmetallic source is approximately 2.0 × 10⁻⁶. -7 Torr up to 8.0×10 -7 Torr, preferably in the range of approximately 3.5 × 10⁻⁶ -7 Torr up to 6.0×10 - 7 Torr, and preferably approximately 4.5 × 10 -7 Torr up to 5.5×10 -7 Torr (e.g., 4.9 × 10) -7 The flux ratio of the nonmetallic source (Se) to the metallic source (Ga) can be maintained between approximately 8 and 15 under the above conditions, preferably between approximately 10 and 13, and particularly preferably between approximately 11.

[0066] Under the above conditions, an epitaxial operation is performed for about 30 to 120 minutes, preferably about 45 to 75 minutes, and particularly preferably about 60 minutes, to form a second epitaxial thin film 2 consisting of a multi-layered two-dimensional semiconductor layer.

[0067] In one specific embodiment, real-time monitoring by high-energy reflected electron diffraction (RHEED) shows that, under surface pretreatment conditions, the nucleation delay time of the GaSe thin film can be significantly shortened to approximately 3 minutes, preferably less than 1 minute (e.g., Figure 6 As shown in the figure, a continuous and clear streaky pattern was observed, confirming its rapid nucleation and subsequent regular layered growth behavior. After the second epitaxial film 2 is formed, a cooling rate between 10°C / min and 30°C / min can be used, preferably between 12°C / min and 20°C / min, and particularly preferably 15°C / min, in order to facilitate stress release and improve the stability of crystal quality of the epitaxial film.

[0068] The in-plane lattice constant of the second epitaxial thin film 2 is approximately 3.6 Å to 4.0 Å along the b-axis, preferably approximately 3.7 Å to 3.9 Å, and particularly preferably approximately 3.785 Å, corresponding to the approximately 3.04 Å in-plane lattice constant along the b-axis of the first epitaxial thin film 1 (a three-dimensional semiconductor material), indicating a certain degree of lattice matching between the two materials. The bandgap of the second epitaxial thin film 2, measured at 25 K, is 1.7 eV to 2.1 eV, preferably approximately 1.75 eV to 1.85 eV, and particularly preferably approximately 1.76 to 1.81 eV, and can be redshifted by approximately 30 meV through strain effects.

[0069] Furthermore, subsequent analyses (such as TEM and photoluminescence PL analysis) confirmed that the two-dimensional semiconductor material (such as GaSe) can generate a non-metal passivation layer when nucleating on the surface of the metal terminal layer. This passivation layer contains the same non-metallic elements as the two-dimensional semiconductor material, such as selenium (Se), and its thickness is approximately at the monolayer to sub-monolayer level. It has a significant passivation effect on the metal terminal layer on the Ga2O3 surface, effectively reducing the interface defect density and improving the interface integrity and carrier transport characteristics of the heterostructure.

[0070] In summary, the process conditions and methods of the second epitaxial operation can effectively achieve the growth of high-quality two-dimensional layered GaSe thin films, and form a mixed-dimensional heterostructure with the Ga2O3 layer of the first epitaxial film, which has good interface cleanliness, lattice matching and photoelectric properties.

[0071] [Heterogeneous Semiconductor Structure] Furthermore, such as Figure 5A and Figure 5B As shown, this embodiment of the invention also provides a heterogeneous semiconductor structure 100, comprising: a substrate S, a first epitaxial thin film 1 (composed of a three-dimensional semiconductor material, such as Ga2O3) formed on the substrate S, and a second epitaxial thin film 2 (composed of a two-dimensional semiconductor material, such as GaSe) formed on the first epitaxial thin film 1. The heterogeneous semiconductor structure 100 may also selectively include a metal termination layer 1a (such as a gallium metal termination layer) and a non-metal passivation layer 1b (such as a selenium passivation layer) formed between the first epitaxial thin film 1 and the second epitaxial thin film 2. The metal termination layer 1a is formed on the first epitaxial thin film 1. The non-metal passivation layer 1b is formed on the metal termination layer 1a and below the second epitaxial thin film 2.

[0072] In terms of thickness range, the first epitaxial film 1 (e.g., a three-dimensional semiconductor material layer composed of gallium oxide Ga2O3) has a thickness of about 20 nanometers to about 50 nanometers, preferably about 28 nanometers to about 45 nanometers, and particularly preferably about 30 nanometers to about 40 nanometers.

[0073] The second epitaxial film 2 (e.g., a gallium selenide (GaSe) layer made of a two-dimensional semiconductor material) is formed in a multilayered stacked structure, with a total thickness of approximately 50 nm to approximately 120 nm, preferably approximately 70 nm to approximately 100 nm, and particularly preferably approximately 80 nm to 90 nm. High-resolution transmission electron microscopy (HRTEM) analysis clearly identifies that the second epitaxial film 2 is composed of multiple layers of two-dimensional structural units TL, and the thickness of each two-dimensional structural unit TL is approximately 0.50 nm to 1.0 nm (e.g., approximately 0.8 nm). The second epitaxial film 2 as a whole has approximately 80 to 130 layers of two-dimensional structural units TL, more preferably approximately 90 to 120 layers.

[0074] Furthermore, a non-metal passivation layer 1b is formed between the first epitaxial film 1 and the second epitaxial film 2. The non-metal passivation layer 1b is formed in the early stage of the second epitaxial operation by the reaction of non-metal atoms (such as selenium, Se) with the metal terminal layer (such as gallium, Ga) on the surface of the first epitaxial film. The non-metal passivation layer is mainly composed of non-metal elements that are the same as the non-metal elements in the two-dimensional semiconductor material, forming a stable interface bonding layer.

[0075] According to high-resolution transmission electron microscopy (HRTEM) analysis, the thickness of the non-metallic passivation layer 1b is approximately 0.3 nm to 1.0 nm, preferably approximately 0.4 nm to 0.8 nm, and particularly preferably approximately 0.5 nm to 0.7 nm, corresponding to an atomic thickness from sub-monolayer to monolayer. This passivation layer effectively seals unsaturated bonds at the interface, reduces the interface defect density, and further improves the subsequent epitaxial nucleation rate, thin film quality, and carrier transport characteristics of two-dimensional semiconductor materials.

[0076] By controlling the above process conditions, continuous two-dimensional and three-dimensional semiconductor material epitaxy can be performed under ultra-high vacuum conditions, successfully preparing two-dimensional and three-dimensional mixed-dimensional heterosemiconductor structures with excellent lattice matching, interface quality, material uniformity and tunable photoelectric properties. This structure can effectively improve the photoresponsivity, photoelectric conversion efficiency and self-powered photodetector characteristics of the device, and has the potential to be applied to wafer-level device manufacturing.

[0077] To illustrate the manufacturing method of the heterosemiconductor structure described in this invention in more detail, several exemplary implementations under different conditions will be described below. Although this invention is not limited to specific parameters or device configurations, the process examples given are based on a plasma-assisted molecular beam epitaxy (PA-MBE) system under ultra-high vacuum conditions, and the differences between processes without surface pretreatment and those with surface pretreatment are shown respectively.

[0078] [Process Example 1: Sample S1, without surface pretreatment] First, a sapphire substrate with c-plane crystals is placed into a vacuum epitaxy system and evacuated to approximately 10 °C. -10 After torsion, the substrate was heated to 450°C at a rate of approximately 10°C / min. Radio frequency oxygen plasma was then introduced, with the RF power set to 300 W and the oxygen flow rate to 1.0 sccm. Simultaneously, the gallium (Ga) atom beam source flux was set to 2.0 × 10⁻⁶. -8 A β-Ga₂O₃ thin film with a thickness of approximately 32 nm was formed on the substrate using a torsion method for 60 minutes. The substrate was then cooled to approximately 60°C at a rate of approximately 20°C / min. The substrate was then heated to 480°C at a rate of approximately 10°C / min, and after the substrate temperature stabilized, the Ga flux was set to approximately 4.5 × 10⁻⁶. -8 Torr and Se fluxes are approximately 4.9 × 10⁻⁶. -7 Torr (Se / Ga flux ratio approximately 11) was used for 60 minutes to perform GaSe thin film epitaxy. Finally, the temperature was lowered to room temperature at approximately 15°C / min to complete the preparation of sample S1.

[0079] [Process Example 2: Sample S2, without surface pretreatment] The process conditions for sample S2 were largely the same as those for sample S1, with the only difference being the substrate temperature setting for the second epitaxial operation. First, a β-Ga₂O₃ thin film with a thickness of approximately 32 nm was prepared, similar to the process in S1. The substrate was cooled to approximately 60°C, and then heated to 425°C at a rate of approximately 10°C / min. After the substrate temperature stabilized, the Ga flux (4.5 × 10⁻⁶) was turned on. -8 Torr) and Se flux (4.9 × 10 - 7 Torr (with a Se / Ga flux ratio of approximately 11), GaSe epitaxy was performed for 60 minutes. Finally, the sample was cooled to room temperature at approximately 15°C / min to complete the preparation of sample S2.

[0080] [Process Example 3: Sample S3, with surface pretreatment] First, following the same steps as S1 and S2, a β-Ga₂O₃ thin film layer with a thickness of approximately 32 nm was formed on the c-sapphire substrate, and the substrate was cooled to approximately 60°C. Then, the temperature was increased to 425°C at approximately 10°C / min, and at this temperature, the Ga atom beam source was activated with a flux of approximately 4.5 × 10⁻⁶. -8Torr performed a surface pretreatment for approximately 5 minutes to deposit Ga atoms onto the Ga2O3 film surface. Subsequently, the temperature was increased to approximately 600°C at approximately 15°C / min and maintained at this temperature for approximately 10 minutes for annealing. Then, the temperature was decreased back to the substrate temperature of 425°C at approximately 15°C / min. After temperature stabilization, the Ga flux (4.5 × 10⁻⁶) was turned on. -8 Torr) and Se flux (4.9 × 10 - 7 Torr (with a Se / Ga flux ratio of approximately 11), GaSe epitaxy was performed for 60 minutes. Finally, the substrate was cooled to room temperature at approximately 15°C / min to complete the preparation of sample S3.

[0081] [In-situ RHEED Analysis] The above process examples one to three use in-situ high-energy electron diffraction (in-situ RHEED) to analyze the epitaxial growth behavior of GaSe on Ga2O3 thin films and observe the effects of different epitaxial conditions on GaSe nucleation and growth quality.

[0082] like Figure 6 As shown, at higher temperature conditions (e.g., 480°C, sample S1), a delayed nucleation phenomenon was observed, requiring approximately 15 to 20 minutes for the blurry pattern to gradually transform into a clear striped diffraction pattern. However, at lower epitaxial temperature conditions (e.g., 425°C, sample S2), the nucleation time of GaSe was shortened to approximately 5 to 10 minutes, indicating an improved nucleation efficiency at lower temperatures.

[0083] In contrast, in the preferred embodiment (sample S3), a Ga-terminated surface is formed on the Ga2O3 surface through a Ga pre-treatment process, which further significantly improves the nucleation behavior of GaSe. According to RHEED real-time observation, under these conditions, the GaSe film can rapidly complete nucleation within about 1 to 2 minutes, quickly producing a clear and well-defined striped diffraction pattern, and maintaining good layered growth behavior.

[0084] Furthermore, the GaSe layer of sample S3, after Ga pretreatment, has an in-plane lattice constant of approximately 3.785 Å according to RHEED analysis, confirming good two-dimensional layered crystal quality and exhibiting significantly improved uniformity and surface coverage.

[0085] [Photoluminescence (PL) Analysis] like Figure 7As shown, photoluminescence (PL) analysis was performed at a low temperature of 25K to compare the differences in PL signals between sample S1 (480°C without pretreatment), sample S2 (425°C without pretreatment), and sample S3 (425°C with Ga surface pretreatment).

[0086] The main PL peak of sample S1 (480°C) is located at approximately 1.77 eV, exhibiting a relatively broad signal profile. The shoulder peaks are located at ~1.76 eV and ~1.81 eV, which are attributed to bound excitons and free excitons, respectively, representing signals related to impurities or oxygen vacancies.

[0087] The main PL peak of sample S2 (425°C) is about 1.78 eV, which is about 30 meV redshift compared to S1. This indicates that the lower growth temperature introduces compressive strain, which effectively controls the bandgap characteristics of the GaSe film.

[0088] Sample S3 (pretreated with Ga at 425°C) also showed a main peak position of about 1.78 eV, which was close to the main peak position of S2. This shows that the Ga pretreatment conditions did not significantly change the main peak energy position, but the signal was clearer and stronger, indicating that Ga pretreatment can further improve crystal quality, reduce defect density and improve luminescence efficiency.

[0089] [High-resolution transmission electron microscopy (HRTEM) analysis] like Figure 8 and Figure 9 As shown, high-resolution transmission electron microscopy (HRTEM) analysis of sample S3 (425°C, Ga pretreated) reveals a clear and contrasting heterojunction structure at the interface between the first epitaxial layer 1 (Ga2O3) and the second epitaxial layer 2 (GaSe). This structure can be attributed to a non-metallic passivation layer 1b (Se passivation layer) with a thickness of approximately 0.4 to 0.8 nm formed between the two layers. This layer provides a clear compositional transition and a stable bonding interface structure between the two layers.

[0090] Furthermore, high-resolution images further confirmed that the GaSe thin film layer above the Se passivation layer exhibits a clear multilayered structure (two-dimensional structural unit TL), with typical two-dimensional crystal characteristics. The van der Waals gap is clearly visible between the layers, proving that the GaSe layer is indeed epitaxially stacked on the Ga2O3 layer in a layered structure. The layers and interlayers of the second epitaxial layer 2 are arranged regularly without obvious dislocations or defects, showing that the epitaxial process is highly ordered.

[0091] Depend on Figure 8 and Figure 9 The high-resolution transmission electron microscopy (HRTEM) analysis results show that the thickness of the first epitaxial film 1 (Ga2O3) formed in sample S3 is about 30 to 40 nanometers, and the thickness of the second epitaxial film 2 (GaSe) is about 80 to 90 nanometers, corresponding to more than 100 two-dimensional structural units (TL). The thickness of the non-metallic passivation layer 1b (Sepassivation layer) between the two is about 0.5 to 0.7 nanometers, which is a monolayer to sub-monolayer structure with good structural stability and interface integrity.

[0092] The analysis results show that Ga surface pretreatment can form a Ga terminal surface on the Ga2O3 surface and further form a Se passivation layer to achieve high-quality heterogeneous integration between two-dimensional and three-dimensional semiconductor materials, effectively reduce interface defects and dislocation density, and ensure the high-quality epitaxial characteristics of the overall structure.

[0093] Applications of heterogeneous semiconductor structures The heterosemiconductor structure of this invention can be applied, for example, to a self-powered broadband photodetector. Specifically, it utilizes a PN heterostructure composed of two-dimensional gallium selenide (GaSe) and three-dimensional gallium oxide (Ga2O3). The band gaps of the two materials respectively cover the visible light (approximately 1.78 eV) to deep ultraviolet (approximately 4.96 eV) range, forming an internal electric field without an external bias voltage, effectively promoting the separation of photogenerated carriers. The device of this invention exhibits high responsivity and high detection rate even at zero bias voltage, making it suitable for low-power, wide-band photoelectric sensing, environmental monitoring, and high-sensitivity military detection devices.

[0094] [Beneficial Effects of the Examples] In this embodiment of the invention, a mixed-dimensional heterosemiconductor structure with a well-defined interface is formed by sequentially epitaxially growing a three-dimensional N-type semiconductor material (such as β-Ga2O3) and a two-dimensional P-type semiconductor material (such as GaSe) on an oxide single-crystal substrate (such as a sapphire substrate).

[0095] The embodiments of the present invention can effectively improve the cleanliness and epitaxial quality of the interface between two-dimensional and three-dimensional materials in heterogeneous semiconductor structures through the above-described technical solutions. Compared with traditional transfer or peel-off stacking methods, the present invention can significantly reduce the interface defect density and enhance the integrity of heterogeneous structure bonding. In addition, the present invention can achieve high-quality heterojunction structures, which have excellent electrical stability and response performance for subsequent optoelectronic component applications (such as self-powered photodetectors).

[0096] In particular, the surface pretreatment process (i.e., Ga vapor deposition and annealing on the surface of the first epitaxial film) introduced in the embodiments can significantly improve the quality and uniformity of subsequent GaSe epitaxy.

[0097] This invention addresses common problems in traditional heterostructures, such as high interface defect density, difficulty in epitaxial nucleation, and interlayer misalignment. By introducing a metal termination layer and forming a non-metallic passivation layer, the surface free energy of the epitaxial layer can be effectively reduced, nucleation uniformity promoted, and a stable bonding interface formed. This enables high-quality, low-defect two-dimensional / three-dimensional heterostructure epitaxy with excellent lattice matching and layered stacking properties. Furthermore, it can be applied to highly sensitive, self-powered optoelectronic components to improve the component's photoresponse efficiency and reliability.

[0098] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Therefore, all equivalent technical changes made based on the description and drawings of the present invention are included within the protection scope of the present invention.

Claims

1. A method for manufacturing a heterogeneous semiconductor structure, characterized in that, The manufacturing method includes: Performing a first epitaxial operation includes: using a vacuum epitaxial system at a depth between 10... -12 Torr to 10 -7 Under a vacuum condition, a first epitaxial thin film composed of a three-dimensional semiconductor material is epitaxially formed on a substrate; wherein the substrate is an oxide single-crystal substrate, and the three-dimensional semiconductor material is an N-type semiconductor material having a three-dimensional crystal structure; and Performing a second epitaxial operation includes: in the vacuum epitaxial system, under conditions of maintaining and not breaking the vacuum, epitaxially forming a second epitaxial film composed of a two-dimensional semiconductor material on the first epitaxial film; wherein the two-dimensional semiconductor material is a P-type semiconductor material with a multilayered crystal structure.

2. The manufacturing method according to claim 1, characterized in that, The vacuum epitaxy system is a molecular beam epitaxy system, and the vacuum conditions are between 10... -11 Torr to 10 -9 Torr.

3. The manufacturing method according to claim 1, characterized in that, The oxide single-crystal substrate is a sapphire single-crystal substrate. The three-dimensional semiconductor material has a first bandgap between 4.8 eV and 5.0 eV and an in-plane lattice constant between 2.8 Å and 3.3 Å in the b-axis direction. The two-dimensional semiconductor material has a second bandgap between 1.9 eV and 2.1 eV, and the relative difference between the in-plane lattice constants of the two-dimensional semiconductor material and the three-dimensional semiconductor material is not greater than 25%.

4. The manufacturing method according to claim 1, characterized in that, The method further includes: a surface pretreatment operation performed between the first epitaxial operation and the second epitaxial operation; wherein the surface pretreatment operation includes: after the first epitaxial operation, performing a vapor deposition pretreatment on the first epitaxial film formed on the substrate using a metal source to form a metal termination layer on the surface of the first epitaxial film.

5. The manufacturing method according to claim 4, characterized in that, The metal atoms in the vapor deposition pretreatment are the same as at least one metal element in the three-dimensional semiconductor material; wherein the metal atoms in the vapor deposition pretreatment form bonds with the oxygen element of the three-dimensional semiconductor material to form the metal terminal layer.

6. The manufacturing method according to claim 5, characterized in that, The second epitaxial operation is performed after the surface pretreatment operation, which includes further forming the second epitaxial film on the metal terminal layer on the first epitaxial film, and forming a non-metallic passivation layer between the interface of the first epitaxial film and the second epitaxial film.

7. The manufacturing method according to claim 6, characterized in that, The three-dimensional semiconductor material of the first epitaxial thin film is β-gallium oxide; the metal atoms in the evaporation pretreatment are gallium; the two-dimensional semiconductor material of the second epitaxial thin film is gallium selenide, and the non-metallic element in the non-metallic passivation layer is selenium.

8. The manufacturing method according to claim 1, characterized in that, The first epitaxial operation includes heating the substrate to a first epitaxial temperature between 400°C and 500°C.

9. The manufacturing method according to claim 8, characterized in that, The first epitaxial operation further includes: oxygen activation using a radio frequency oxygen plasma source of the vacuum epitaxial system, with a radio frequency power of 250W to 350W, an oxygen gas flow rate of 0.5sccm to 2sccm, a gallium atom source as the metal source, and a metal atom flux of 1.0 × 10⁻⁶. -8 Torr up to 5.0×10 -8 The first epitaxial film is formed under conditions of Torr and epitaxial time of 30 to 120 minutes; wherein the surface roughness of the first epitaxial film is not greater than 1 nm.

10. The manufacturing method according to claim 4, characterized in that, In the surface pretreatment process, the vapor deposition pretreatment first heats the substrate to a vapor deposition temperature of 380°C to 460°C; then the metal source is turned on for 1 to 10 minutes of atomic pre-evaporation to form the metal terminal layer.

11. The manufacturing method according to claim 10, characterized in that, The metal source flux in the vapor deposition pretreatment is between 1.0 × 10⁻⁶. -8 Up to 8.0×10 -8 Torr, wherein the metal atoms used in the metal source are the same as the metal elements of the three-dimensional semiconductor material; the surface pretreatment operation is followed by raising the substrate temperature from the evaporation temperature to an annealing temperature of 550°C to 650°C, maintaining it for 5 to 15 minutes, and then cooling it down to form the metal terminal layer.

12. The manufacturing method according to any one of claims 1 to 11, characterized in that, The second epitaxial operation involves adjusting the substrate to a second epitaxial temperature between 410°C and 440°C; subsequently, a metal source and a non-metal source in the vacuum epitaxial system are turned on to perform epitaxy and form the second epitaxial film.

13. The manufacturing method according to claim 12, characterized in that, The flux of the metal source is in the range of 2.0 × 10⁻⁶. - 8 Torr up to 8.0×10 -8 Torr, the nonmetallic source flux ranges from 2.0 × 10⁻⁶. -7 Torr up to 8.0×10 -7 Torr, and the flux ratio between the non-metallic source and the metallic source is between 8 and 15; wherein the metallic source is a gallium atom beam source, the non-metallic source is a selenium atom beam source, and the epitaxial time of the second epitaxial operation is between 30 minutes and 120 minutes.

14. The manufacturing method according to claim 12, characterized in that, Real-time monitoring via high-energy reflection electron diffraction during the second epitaxial operation showed that the nucleation delay time during the growth of the second epitaxial thin film was less than 3 minutes.

15. A heterogeneous semiconductor structure, characterized in that, The heterosemiconductor structure includes: A substrate; wherein the substrate is an oxide single crystal substrate; A first epitaxial thin film is formed on the substrate and is composed of a three-dimensional semiconductor material; wherein the three-dimensional semiconductor material is an N-type semiconductor material with a three-dimensional crystal structure; and A second epitaxial thin film is formed on the first epitaxial thin film and is composed of a two-dimensional semiconductor material; wherein the two-dimensional semiconductor material is a P-type semiconductor material with a multilayered crystal structure.

16. The heterogeneous semiconductor structure according to claim 15, characterized in that, The oxide single-crystal substrate is a sapphire single-crystal substrate. The three-dimensional semiconductor material has a first bandgap between 4.8 eV and 5.0 eV and an in-plane lattice constant between 2.8 Å and 3.3 Å in the b-axis direction. The two-dimensional semiconductor material has a second bandgap between 1.9 eV and 2.1 eV, and the relative difference between the in-plane lattice constants of the two-dimensional semiconductor material and the three-dimensional semiconductor material is not greater than 25%.

17. The heterogeneous semiconductor structure according to claim 15, characterized in that, The heterogeneous semiconductor structure further includes: A metal terminal layer is formed between the first epitaxial film and the second epitaxial film; A non-metallic passivation layer is formed between the first epitaxial film and the second epitaxial film; The metal terminal layer is formed on the first epitaxial film, and the non-metallic passivation layer is formed on the metal terminal layer and located below the second epitaxial film. The metal atoms in the metal terminal layer are the same as the metal elements in the three-dimensional semiconductor material, and the non-metal elements in the non-metal passivation layer are the same as the non-metal elements in the two-dimensional semiconductor material.

18. The heterogeneous semiconductor structure according to claim 17, characterized in that, The first epitaxial film has a thickness of 20 nanometers to 50 nanometers, the second epitaxial film is formed by stacking multiple two-dimensional structural units with a total thickness of between 50 nanometers and about 120 nanometers, the thickness of each two-dimensional structural unit is between 0.50 nanometers and 1.0 nanometers, and the thickness of the non-metallic passivation layer is between 0.3 nanometers and 1.0 nanometers.

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