Confined metal atom intercalated graphene and preparation method and application thereof

Abstract

The application discloses a confined metal atom intercalated graphene and a preparation method and application thereof. The method comprises the following steps: after SiC-based graphene with a metal thin layer grown on the surface is pasted together in a "face-to-face" mode, the SiC-based graphene is placed in a closed vacuum container, a confined space constructed by the SiC-based graphene can effectively control the volatilization of metal atoms, the randomness of metal intercalation is inhibited, and the metal intercalation area is increased. The metal intercalation technology is simple and effective, can be popularized to metal intercalation of various SiC-based graphene and buffer layers, and is expected to promote large-scale and uniform metal intercalation of SiC-based graphene, and provide important guidance and reference value for application in the fields of microelectronics and two-dimensional metal materials.

Description

Technical Field

[0001] This invention belongs to the field of two-dimensional material preparation and modification technology, and relates to a confined metal atom intercalated graphene, its preparation method and application. Background Technology

[0002] Since its invention, the integrated circuit industry has faced a technological bottleneck stemming from the reduction in transistor channel size. Therefore, from the perspective of exploring new materials, finding novel semiconductor materials to replace single-crystal silicon is urgently needed for the development and application of future microelectronic devices. Graphene is composed of carbon atoms through sp... 2 Hexagonal honeycomb-shaped two-dimensional crystals formed by hybridization possess excellent electron mobility, thermal conductivity, and mechanical properties, demonstrating broad application prospects in the information field. Epitaxial graphene is prepared through high-temperature pyrolysis of single-crystal SiC substrates, allowing for direct application in electronic device fabrication without transfer. Combined with traditional silicon-based processes, it holds promise as an ideal candidate semiconductor material for the post-Moore's Law era. Since its discovery, SiC-based graphene has attracted significant attention. A collaborative research effort between Professor Ma Lei's team at Tianjin University and Professor Walter A. de Heer's group at Georgia Institute of Technology has achieved a major breakthrough, preparing a regular, ordered monolayer of graphene on the SiC surface using quasi-equilibrium annealing technology. This has created the world's first functional graphene semiconductor, opening up practical applications for graphene in the semiconductor field.

[0003] SiC-based graphene is considered an ideal candidate material for next-generation high-performance electronic devices. However, the bonding state between the graphene surface layer and the SiC substrate has always been a key issue restricting the development and application of SiC-based graphene. Currently, metal atom intercalation technology can only randomly form an extremely thin layer of metal atoms between graphene and the SiC substrate, resulting in very limited graphene ionization effects. Two factors constrain current metal intercalation technology: firstly, the surface morphology of SiC-based graphene after high-temperature pyrolysis is extremely non-uniform, containing numerous pores, buffer layer structures, and graphene of varying thicknesses, making large-scale uniform metal intercalation difficult. Secondly, the migration and volatilization rates of metal atoms on the graphene surface are relatively fast, and conventional annealing techniques offer no means to limit metal atom volatilization, failing to effectively control the metal intercalation region and area. Therefore, solving the problems of substrate uniformity and intercalation randomness is sufficient to ensure large-scale uniform metal intercalation modification of SiC-based graphene and more effectively address the bonding problem of the intermediate interface layer. Therefore, it is necessary to optimize metal intercalation technology. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a confined metal atom intercalated graphene, its preparation method, and its application, thereby solving the problem that the prior art cannot obtain large-scale uniform metal intercalated SiC-based graphene.

[0005] This invention is achieved through the following technical solution:

[0006] A method for preparing confined metal atom intercalated graphene includes the following steps:

[0007] S1: Heat treatment of single-crystal SiC substrate to obtain SiC-based graphene;

[0008] S2: A metal nanofilm is grown on the surface of each of the two SiC-based graphene sheets;

[0009] S3: After bonding two pieces of SiC-based graphene with metal nanolayers, annealing is performed under vacuum conditions to obtain the confined metal atom intercalated graphene; during bonding, the two metal nanolayers are in contact.

[0010] Preferably, in step S1, before heat treatment of the single-crystal SiC substrate, a pretreatment of the single-crystal SiC substrate is further included; the pretreatment process is as follows: under vacuum conditions, the single-crystal SiC substrate is heated to 550-650°C and held at that temperature for 8 hours.

[0011] Preferably, in step S1, the heat treatment temperature is 1250℃~1400℃, and the heat treatment time is 10~15min.

[0012] Preferably, in step S2, a metal nanofilm is grown on the surface of the SiC-based graphene using molecular beam epitaxy; during the growth process, the metal source is heated to 500–700°C, and the growth time is 10–20 min; the thickness of the metal nanofilm is 5–10 nm.

[0013] Preferably, in step S3, the sample heating rate is 25-35℃ / min, and the sum of the heating time and the holding time does not exceed 1h.

[0014] Preferably, in step S3, the annealing temperature is 600-800℃ and the annealing time is 20-30 min.

[0015] Preferably, in step S3, the vacuum degree is 1×10⁻⁶. -2 ~5×10 -2 Torr.

[0016] Preferably, the metal in the metal nanofilm is In or Cu.

[0017] A confined metal atom intercalated graphene is prepared by the above method.

[0018] The above-mentioned application of confined metal atom intercalated graphene in the field of integrated circuits.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] This invention discloses a method for preparing confined metal atom intercalated graphene. The method involves bonding SiC-based graphene with metal nanolayers grown on its surface together in a "face-to-face" manner and then annealing it under vacuum conditions. This method can effectively construct a confined space, which can effectively regulate the volatilization of metal atoms, suppress the randomness of metal intercalation, and thus increase the metal intercalation area.

[0021] Furthermore, in step S1, before heat treatment of the single-crystal SiC substrate, a pretreatment of the single-crystal SiC substrate is also included; the pretreatment process is as follows: under vacuum conditions, the single-crystal SiC substrate is heated to 550-650°C and held for 8 hours. This pretreatment process can remove impurities such as surface water vapor and adsorbates.

[0022] Furthermore, in step S1, the heat treatment temperature is 1250℃~1400℃ and the heat treatment time is 10~15min, which allows graphene thin layers to be fully grown on the SiC surface.

[0023] Furthermore, in step S2, a metal nanofilm is grown on the surface of the SiC-based graphene using molecular beam epitaxy. During the growth process, the metal source is heated to 500–700°C for 10–20 min, which allows a metal nanofilm with a thickness of 5–10 nm to be grown on the surface of the SiC graphene. This thickness allows the surface of the SiC graphene to be uniformly covered by metal atoms.

[0024] Furthermore, in step S3, the sample heating rate is 25-35℃ / min, and the sum of the heating time and the holding time does not exceed 1 hour. If the time is too long, the infiltrated metal atoms will overflow and cannot effectively form intercalated graphene.

[0025] Furthermore, in step S3, the vacuum degree is 1×10⁻⁶. -2 ~5×10 -2 Torr, with a heating rate of 25–35 °C / min, an annealing temperature of 600–800 °C, and an annealing time of 20–30 min, allows metal atoms to be effectively inserted into the graphene layer.

[0026] Furthermore, in the metal nanofilm, the metal is In or Cu, which can effectively yield graphene with In or Cu atom intercalation. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic flowchart of a method for preparing confined metal atom intercalated graphene according to the present invention;

[0029] Figure 2 This is a schematic diagram of confined metal atom intercalation in the present invention;

[0030] Figure 3 The above are the SEM characterization results of confined metal atom intercalated graphene in Example 2 of this invention.

[0031] Figure 4 The Raman spectral characterization results of confined metal atom intercalated graphene in Example 3 of this invention are shown.

[0032] Among them, 1. Sealed vacuum container, 2. Substrate placement frame, 3. SiC substrate, 4. Graphene, and 5. Metal atoms. Detailed Implementation

[0033] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0034] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0035] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0036] In this article, unless otherwise specified, the terms “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of”. For example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a”.

[0037] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0038] like Figure 1 As shown, this invention provides a method for preparing confined metal atom intercalated graphene. This invention mainly utilizes confined intercalation technology to achieve large-scale, uniform metal atom intercalation in SiC-based graphene, specifically including the following steps:

[0039] S1: Pre-treat the single-crystal SiC substrate, and then heat-treat the pre-treated single-crystal SiC substrate to obtain SiC-based graphene.

[0040] In this step, the SiC substrate is a Grade A sample, and either the Si or C side can be used, with single-sided polishing.

[0041] The pretreatment process is as follows: a clean single-crystal SiC substrate is introduced into a vacuum chamber. Under vacuum conditions, the single-crystal SiC substrate is heated using a direct current and degassed to remove surface water vapor and adsorbates. During this pretreatment, the direct current is 0.5–0.7 A, resulting in a heating temperature of 550–650 °C, and the degassed time is 8 hours. In this step, the background vacuum level of the sample preparation chamber is less than 5 × 10⁻⁶. -10 Torr.

[0042] The heat treatment process is as follows: the single crystal SiC substrate is heated by direct current to perform heat treatment; the direct current is 2.0 to 2.5A, the heat treatment temperature is 1250℃ to 1400℃, and the heat treatment time is 10 to 15 minutes.

[0043] S2: A metal nanofilm is grown on the surface of each of the two SiC-based graphene sheets;

[0044] Specifically, a metal nanofilm is grown on the surface of SiC-based graphene using molecular beam epitaxy. During the growth process, a K-Cell evaporation source is used to heat the metal source to 500–700°C using a direct current of 1.8–2.1 A, and the growth time is 10–20 min. The thickness of the metal nanofilm is 5–10 nm.

[0045] S3: As Figure 2As shown, two SiC-based graphene sheets with grown metal nanolayers are bonded together and then annealed under vacuum conditions to obtain the confined metal atom intercalated graphene, thus achieving metal atom intercalation. During bonding, the two metal nanolayers are in contact, meaning the two substrates are bonded together in a "face-to-face" manner. In this step, the annealing temperature is 600–800°C, the annealing time is 20–30 minutes, and the vacuum level of the furnace is less than 5 × 10⁻⁶. -2 Torr.

[0046] Furthermore, the present invention can be used in, for example Figure 2 The confined intercalation process is completed in the device shown. Specifically, graphene 4 is first grown on SiC substrate 3 to obtain SiC-based graphene. Then, metal atoms 5 are grown on SiC-based graphene. After the two SiC-based graphene sheets with metal nanosheets are bonded "face to face", they are placed in substrate placement frame 2. Then, the entire material is placed in a sealed vacuum container 1 for confined intercalation.

[0047] This invention utilizes a confined metal atom intercalation technique to achieve large-area, uniform metal intercalation of SiC-based graphene simply and rapidly. The "face-to-face" bonding method creates a confined space within a sealed vacuum container. Under heating and annealing conditions, the volatilization of metal atoms can be effectively controlled, suppressing the randomness of metal intercalation and thus increasing the intercalation area. This metal intercalation technique is simple and effective, and can be extended to various types of SiC-based graphene and buffer layers. It can advance the large-scale, uniform metal intercalation of SiC-based graphene, providing important guidance and reference value for applications in microelectronics and two-dimensional metal materials. In this method, the uniform surface graphene on the SiC base provides an excellent substrate for large-area metal atom intercalation. The SiC-based intercalated graphene obtained by this technique exhibits good near-free properties.

[0048] This invention relates to graphene, a novel carbon-based material for microelectronics, and discloses a method for confined metal atom intercalation of graphene. SiC-based graphene with thin metal layers on its surface is bonded together face-to-face and placed in a sealed vacuum container. The resulting confined space effectively controls the volatilization of metal atoms, suppresses the randomness of metal intercalation, and thus increases the intercalation area. This metal intercalation technique is simple and effective, and can be extended to the metal intercalation of various SiC-based graphenes and buffer layers. It is expected to advance the large-scale, uniform metal intercalation of SiC-based graphene, providing important guidance and reference value for applications in microelectronics and two-dimensional metal materials.

[0049] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0050] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0051] Example 1

[0052] The Si-terminated single-crystal 6H-SiC(0001) substrate was heated to 580℃ under DC conditions of 0.51A and degassed for 8 hours; the vacuum in the sample preparation chamber was maintained at 2.5 × 10⁻⁶. -10 The SiC substrate was rapidly heated to 1300±20℃ using a DC current of 2.1A for 15 min; the sample was then cooled and set aside. The metallic In source material was heated to 550℃ using a K-Cell evaporation apparatus at a heating current of 1.9A for 12 min. Both substrates were then removed from the growth chamber, placed in a confined vacuum apparatus, and heated to 650℃, maintaining an annealing time of 20 min at a vacuum level of 1.1×10⁻⁶. -2 Torr.

[0053] Example 2

[0054] The single-crystal 6H-SiC(0001) substrate was heated to 600℃ under DC conditions of 0.51A and degassed for 8 hours; the vacuum in the sample preparation chamber was maintained at 4.5 × 10⁻⁶. -10 The SiC substrate was rapidly heated to 1350±20℃ using a 2.3A DC current for 10 min; the sample was then cooled and set aside. The Cu source material was heated to 650℃ using a K-Cell evaporation apparatus at a current of 2.0A for 10 min. Both substrates were then removed from the growth chamber, placed in a confined vacuum apparatus, and heated to 700℃, annealed for 20 min, with the vacuum level maintained at 1.5×10⁻⁶. -2 Torr.

[0055] Figure 3This presents the SEM characterization results of confined metal atom intercalation graphene. SEM measurements show that although the surface of the intercalated graphene has altered the original stepped structure, it remains relatively smooth. Metal atoms enter the interface layer between graphene and the SiC substrate, passivating the Si atoms in the SiC buffer layer and exfoliating the upper graphene layer from the SiC substrate, thus achieving ionization modification of the graphene. This embodiment demonstrates that confined metal atom intercalation can simply and rapidly achieve ionization modification of SiC-based graphene, obtaining large-area, high-quality near-free graphene.

[0056] Example 3

[0057] The C-terminated single-crystal 6H-SiC(000-1) substrate was heated to 580℃ under DC conditions of 0.55A and degassed for 8 hours; the vacuum in the sample preparation chamber was maintained at 3.5 × 10⁻⁶. -10 The SiC substrate was rapidly heated to 1250±20℃ using a 2.0A DC current for 20 min; the sample was then cooled and set aside. The Cu source material was heated to 700℃ using a K-Cell evaporation apparatus at a current of 2.1A for 12 min. Both substrates were then removed from the growth chamber, placed in a confined vacuum apparatus, and heated to 800℃, annealed for 13 min, with the vacuum level maintained at 2.5×10⁻⁶. -2 Torr.

[0058] Figure 4 The results are shown in the Raman spectroscopy analysis. The intercalated graphene obtained under these process conditions was subjected to Raman spectroscopy at an excitation wavelength of 633 nm. The results show that the 2D peak of this graphene is very distinct and exhibits excellent symmetry, with an intensity significantly greater than the G peak of graphene. This indicates that the obtained intercalated graphene possesses good near-free ionization characteristics. This embodiment demonstrates that confined metal atom intercalation technology can obtain high-quality SiC-based near-free graphene.

[0059] Example 4

[0060] This invention provides a method for preparing confined metal atom intercalated graphene, comprising the following steps:

[0061] S1: The single-crystal SiC substrate is introduced into the vacuum chamber. Under vacuum conditions, the single-crystal SiC substrate is heated to 550°C using DC current and held for 8 hours to remove surface water vapor and adsorbents and other impurities, thus obtaining a clean SiC substrate. The pretreated clean SiC substrate is then heated to 1250°C and held for 15 minutes to obtain SiC-based graphene.

[0062] S2: A metal nanofilm was grown on the surface of the SiC-based graphene using molecular beam epitaxy. During the growth process, a K-Cell evaporation source was used to heat the metal source to 500°C for 20 minutes, and the thickness of the resulting metal nanofilm was 5 nm.

[0063] S3: Two SiC-based graphene sheets with metal nanolayers grown on them are bonded together face-to-face and then annealed under vacuum conditions to obtain the confined metal atom intercalated graphene. In this step, the annealing temperature is 600℃, the annealing time is 30 min, and the vacuum degree is 1.5 × 10⁻⁶. -2 Torr.

[0064] Example 5

[0065] This invention provides a method for preparing confined metal atom intercalated graphene, comprising the following steps:

[0066] S1: The single-crystal SiC substrate is introduced into the vacuum chamber. Under vacuum conditions, the single-crystal SiC substrate is heated to 650°C using DC current and held for 8 hours to remove surface water vapor and adsorbents and other impurities, thus obtaining a clean SiC substrate. The pretreated clean SiC substrate is then heated to 1400°C and held for 10 minutes to obtain SiC-based graphene.

[0067] S2: A metal nanofilm was grown on the surface of the SiC-based graphene using molecular beam epitaxy. During the growth process, a K-Cell evaporation source was used to heat the metal source to 700°C for 10 minutes, and the thickness of the resulting metal nanofilm was 7 nm.

[0068] S3: Two SiC-based graphene sheets with grown metal nanolayers are bonded face-to-face and then annealed under vacuum conditions to obtain the confined metal atom intercalated graphene. In this step, the annealing temperature is 800℃, the annealing time is 20 min, and the vacuum degree is 3.5 × 10⁻⁶. -2 Torr.

[0069] Example 6

[0070] This invention provides a method for preparing confined metal atom intercalated graphene, comprising the following steps:

[0071] S1: The single-crystal SiC substrate is introduced into the vacuum chamber. Under vacuum conditions, the single-crystal SiC substrate is heated to 600℃ using DC current and held for 8 hours to remove surface water vapor and adsorbents and other impurities, thus obtaining a clean SiC substrate. The pretreated clean SiC substrate is then heated to 1300℃ and held for 13 minutes to obtain SiC-based graphene.

[0072] S2: A metal nanofilm was grown on the surface of the SiC-based graphene using molecular beam epitaxy. During the growth process, a K-Cell evaporation source was used to heat the metal source to 600°C for 15 minutes, and the thickness of the resulting metal nanofilm was 7 nm.

[0073] S3: Two pieces of SiC-based graphene with metal nanolayers grown on them are bonded face-to-face and then annealed under vacuum conditions to obtain the confined metal atom intercalated graphene. In this step, the annealing temperature is 700℃, the annealing time is 25 min, and the vacuum degree is 5×10⁻⁶. -2 Torr.

[0074] This invention utilizes a "face-to-face" confined annealing technique to restrict the random volatilization of metal atoms, enabling large-area metal atom intercalation into SiC-based graphene on two substrates: independent uniform SiC buffer layers and flat C-plane polycrystalline graphene. This invention solves the technical challenges of uniform intercalation in Si-plane graphene and grain boundary optimization in C-plane polycrystalline graphene, providing insights for large-scale metal intercalation and ionization modification of SiC-based graphene.

[0075] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing confined metal atom intercalated graphene, characterized in that, Includes the following steps: S1: Heat treatment of single-crystal SiC substrate to obtain SiC-based graphene; S2: A metal nanofilm is grown on the surface of each of the two SiC-based graphene sheets; S3: After bonding two pieces of SiC-based graphene with metal nanolayers face to face, annealing is performed under vacuum conditions to obtain the metal atom intercalated graphene; during bonding, the two metal nanolayers are in contact. In step S3, the sample heating rate is 25~35℃ / min, and the sum of the heating time and the holding time does not exceed 1h; In step S3, the annealing temperature is 600~800℃ and the annealing time is 20~30min; In step S3, the vacuum degree is 1 x 10 -2 -5 x 10 -2 Torr.

2. The method of claim 1, wherein the method is characterized by: In step S1, before heat treatment of the single-crystal SiC substrate, a pretreatment of the single-crystal SiC substrate is also included; the pretreatment process is as follows: under vacuum conditions, the single-crystal SiC substrate is heated to 550~650℃ and held for 8 hours.

3. The method of claim 1, wherein the method is characterized by: In step S1, the heat treatment temperature is 1250℃~1400℃, and the heat treatment time is 10~15min.

4. The method of claim 1, wherein the method is characterized by: In step S2, a metal nanofilm is grown on the surface of the SiC-based graphene using molecular beam epitaxy. During the growth process, the metal source is heated to 500-700°C and the growth time is 10-20 min. The thickness of the metal nanofilm is 5-10 nm.

5. The method of claim 1, wherein the method is characterized by: The metal nanofilm is made of In or Cu.

6. A confined metal atom intercalated graphene, characterized in that, It is prepared by the method described in any one of claims 1 to 5.

7. The application of the confined metal atom intercalated graphene as described in claim 6 in the field of integrated circuits.

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