Ultra-large single crystal domain quasi-suspended graphene and preparation method thereof

Abstract

The present invention belongs to the technical field of epitaxial graphene, and discloses a super-large single crystal domain quasi-suspended graphene and a preparation method thereof. Semiconductor graphene is first prepared on the surface of a SiC substrate; then the semiconductor graphene is prepared into quasi-suspended graphene by hydrogen intercalation. The present invention first directly grows on an insulating substrate so that the width of the graphene single crystal is expanded to 500 μm, and the length reaches the millimeter level, while the growth is uniform and has no obvious defects; then the coupling effect of the substrate on the graphene is weakened by hydrogen intercalation, so that super-large single crystal domain quasi-suspended graphene is obtained, so that the room temperature mobility can reach 3300 cm 2 / V·s, which is at least three times that of traditional epitaxial graphene; the top-gate device prepared with quasi-suspended graphene exhibits ultra-long ballistic transport performance at room temperature that can reach the centimeter level. Therefore, the present invention can be applied to the field of integrated circuits and will bring new prospects for the development of the electronics field.

Description

Technical Field

[0001] The invention belongs to the technical field of epitaxial graphene, and specifically relates to quasi-suspended graphene and a preparation method thereof. Background Art

[0002] The rapid development of the semiconductor information industry has greatly changed the way people live. This rapid development is achieved by the continuous miniaturization of electronic components. However, when Moore's Law approaches the physical limit, the ceiling of silicon chip manufacturing technology is within reach. In the post-Moore era, the density of integrated circuits can be increased by miniaturizing the size of devices. Unfortunately, it is difficult for traditional materials to break through their own limits, and the development of integrated circuits has to be further promoted through the research and development of new materials, new structures and new principle devices. Speaking of new materials, two-dimensional materials have been increasingly valued in recent years due to their atomic-level thickness and excellent performance. Graphene is the leader among two-dimensional materials, not only because it is the first two-dimensional material discovered, but also because it has great potential application value in mechanics, electronics, optics, sensing, energy and other fields, and is considered to be the cornerstone for replacing Si-based materials.

[0003] Compared with many other graphene growth methods, epitaxial growth of graphene using single-crystal SiC substrates can effectively avoid the introduction of defects in the preparation of electronic devices, such as wrinkles, cracks, impurity contamination and other unfavorable factors. Most importantly, the epitaxial graphene process is compatible with modern semiconductor processes. As far as the current development trend is concerned, this seems to be the only basic material that can be used to prepare two-dimensional nanoelectronic devices. Since the Si sublimation rate of the C surface of SiC is difficult to control, the grown graphene is generally multilayer. The Si surface can generally grow a large area of ​​single-layer epitaxial graphene, thus becoming the most widely studied platform. However, the mobility of single-layer graphene on the Si surface is lower than that of mechanically exfoliated graphene and CVD graphene. This is because the substrate and buffer layer have a decisive influence on the mobility of single-layer epitaxial graphene. Single-layer epitaxial graphene is severely n-type doped by the substrate and buffer layer, resulting in low mobility. The buffer layer has an atomic arrangement similar to that of graphene. Since its own carbon atoms and substrate silicon atoms are partially bonded, it does not have the intrinsic properties of graphene. Quasi-free standing graphene can be obtained through hydrogen intercalation, which greatly weakens the coupling with the substrate, and the mobility hardly changes with temperature. However, it is still limited by step scattering and the width of the terrace, and the development of single-domain graphene has been stagnant. The growth process of Si-surface epitaxial graphene is inevitably affected by the step bunching phenomenon. The epitaxial graphene at the steps is preferentially nucleated, and the growth rate is significantly faster than the growth of graphene at the terraces. The terraces are generally covered with a single layer of graphene, while the steps are generally covered with double or triple layers of graphene. It is important that the steps and double (or triple) layers of graphene have a scattering effect on carriers, which will also affect the mobility of single-layer epitaxial graphene.

[0004] In summary, the development of epitaxial graphene faces the following challenges: 1) Affected by the substrate and buffer layer, it is n-type doped and has low mobility; 2) The mobility is temperature-dependent; 3) It is scattered by steps and double (or triple) layers of graphene at the steps, that is, the performance of graphene is affected by the morphology; 4) The epitaxial graphene covering the platform is single-layer and has good uniformity, but the platform width is generally less than 10μm due to the limitations of the growth process, and the length does not exceed 50μm; 4) Single-domain quasi-suspended graphene is greatly affected by size. Summary of the invention

[0005] The present invention aims to overcome the related technical problems of existing epitaxial graphene and provide a super-large single crystal domain quasi-suspended graphene and a preparation method thereof; a single-layer single crystal semiconductor graphene having super-large crystal domains and super-high room temperature mobility is directly grown on an insulating substrate first, and then a super-large single crystal domain quasi-suspended graphene having high room temperature mobility and a centimeter-level super-long ballistic free path at room temperature is obtained by hydrogen intercalation.

[0006] In order to solve the above technical problems, the present invention is implemented by the following technical solutions:

[0007] According to one aspect of the present invention, there is provided an ultra-large single-crystal domain quasi-suspended graphene, comprising a silicon carbide substrate, wherein the Si surface of the silicon carbide substrate is prepared with uniformly grown quasi-suspended graphene; the quasi-suspended graphene is a single layer, and its crystal domain width can reach 500 microns and its length is sub-centimeter level; the quasi-suspended graphene has a centimeter-level ballistic transport free path at room temperature.

[0008] Furthermore, the crystal domain width of the semiconductor graphene is greater than 200 microns, and the room temperature mobility of the quasi-suspended graphene can reach 3300 cm 2 / (V·s).

[0009] Furthermore, the quasi-suspended graphene is not bonded to the SiC substrate and has semi-metallic properties.

[0010] Furthermore, the silicon carbide substrate is 6H, 4H or 3C.

[0011] According to another aspect of the present invention, a method for preparing the above-mentioned ultra-large single-crystal domain quasi-suspended graphene is provided, comprising the following preparation process:

[0012] (i) preparing the semiconductor graphene on the surface of the SiC substrate; the semiconductor graphene is a single layer and grows uniformly, the crystal domain width of the semiconductor graphene can reach 500 microns, the length is sub-centimeter level, and the room temperature mobility reaches at least 4500cm 2 / (V·s);

[0013] (ii) preparing the semiconductor graphene into quasi-suspended graphene through hydrogen intercalation.

[0014] Furthermore, the semiconductor graphene can be obtained by the following three methods:

[0015] A: The first method for preparing the semiconductor graphene is carried out according to the following steps:

[0016] (1) taking two SiC substrates for pretreatment, and preparing a carbon film on the C surface of one of the SiC substrates after the pretreatment;

[0017] (2) stacking two SiC substrates and placing them in a crucible, with the Si surfaces of the two SiC substrates facing each other;

[0018] (3) annealing the crucible stacked with two SiC substrates under vacuum conditions to clean the SiC substrates;

[0019] (4) heating the crucible stacked with two SiC substrates in an argon atmosphere; heating the SiC substrates in an argon atmosphere to perform preliminary morphology focusing;

[0020] (5) The crucible stacked with two SiC substrates is further heated in an argon atmosphere to grow semiconductor graphene, thereby obtaining semiconductor graphene on both SiC substrates.

[0021] Preferably, in the pretreatment of step (1), the two SiC substrates are subjected to mechanical and chemical polishing, followed by ultrasonic cleaning and N 2 dry.

[0022] Furthermore, the carbon film in step (1) is one of photoresist, PMMA and amorphous carbon, and the carbon film is prepared by one of high temperature decomposition, physical evaporation, chemical plating and coating.

[0023] Preferably, the annealing temperature under vacuum conditions in step (3) is 900-950° C. and the time is 20-30 min.

[0024] Preferably, the temperature of heating the SiC substrate in step (4) is 1250-1300° C., and the heating time is 20-30 min.

[0025] Preferably, the further heating in step (5) is performed at a temperature of 1560°C-1700°C and for a time of 50-600 min.

[0026] B: The second method for preparing the semiconductor graphene is carried out according to the following steps:

[0027] (1) Take two SiC substrates for pretreatment;

[0028] (2) stacking two SiC substrates and placing them in a crucible, with the C surfaces of the two SiC substrates facing the Si surfaces;

[0029] (3) annealing the crucible stacked with two SiC substrates under vacuum conditions to clean the SiC substrates;

[0030] (4) heating the crucible stacked with two SiC substrates in an argon atmosphere; heating the SiC substrates in an argon atmosphere to perform preliminary morphology focusing;

[0031] (5) The crucible stacked with two SiC substrates is further heated in an argon atmosphere to grow semiconductor graphene, thereby obtaining semiconductor graphene on a SiC substrate.

[0032] Preferably, in the pretreatment of step (1), the two SiC substrates are subjected to mechanical and chemical polishing, followed by ultrasonic cleaning and N 2dry.

[0033] Preferably, the annealing temperature under vacuum conditions in step (3) is 900-950° C. and the time is 20-30 min;

[0034] Preferably, the temperature of heating the SiC substrate in step (4) is 1250-1300° C., and the heating time is 20-30 min.

[0035] Preferably, the further heating in step (5) is performed at a temperature of 1560°C-1700°C and for a time of 50-600 min.

[0036] C: The third method for preparing the semiconductor graphene is carried out according to the following steps:

[0037] (1) Pre-treating a SiC substrate and placing it in a modified crucible, wherein the modified crucible has a structure in which the outer surface of the bottom is a plane;

[0038] (2) annealing the modified crucible stacked with two SiC substrates under vacuum conditions to clean the SiC substrates;

[0039] (3) heating the modified crucible stacked with two SiC substrates in an argon atmosphere; heating the SiC substrates in an argon atmosphere to perform preliminary morphology focusing;

[0040] (4) The modified crucible stacked with two SiC substrates is further heated in an argon atmosphere to grow semiconductor graphene, thereby obtaining semiconductor graphene on the SiC substrate.

[0041] Preferably, in the pretreatment of step (1), the two SiC substrates are subjected to mechanical and chemical polishing, followed by ultrasonic cleaning and N 2 dry.

[0042] Preferably, the annealing temperature under vacuum conditions in step (3) is 900-950° C. and the time is 20-30 min;

[0043] Preferably, the temperature of heating the SiC substrate in step (4) is 1250-1300° C., and the heating time is 20-30 min.

[0044] Preferably, the further heating in step (5) is performed at a temperature of 1560°C-1700°C and for a time of 50-600 min.

[0045] Furthermore, the quasi-suspended graphene is prepared by hydrogen intercalation, which is to heat the semiconductor graphene at 900-1300° C. for 10-80 min in a hydrogen atmosphere.

[0046] Furthermore, the hydrogen flow rate of the hydrogen atmosphere is 50-100 sccm.

[0047] The beneficial effects of the present invention are:

[0048] The present invention first directly grows on an insulating substrate, and the width of the graphene single crystal is extended to 500μm, reaching the millimeter level, and the growth is uniform without obvious defects; then the coupling effect of the substrate on the graphene is weakened by hydrogen intercalation, and ultra-large single crystal domain quasi-suspended graphene is obtained, so that the room temperature mobility can reach 3300cm 2 / V·s, which is at least three times that of traditional epitaxial graphene; the top-gate device prepared with quasi-suspended graphene exhibits ultra-long ballistic transport performance at room temperature up to centimeter level. Therefore, the present invention can be applied to the field of integrated circuits, greatly reducing chip power consumption and heating problems, and will bring new prospects for the development of the electronics field. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a flow chart of the quasi-suspended graphene growth of the present invention.

[0050] Figure 2 It is a schematic diagram of the atomic structure of the quasi-suspended graphene of the present invention (side view), wherein the yellow solid spheres represent Si atoms, the gray solid spheres represent C atoms, and the blue solid spheres represent H atoms.

[0051] Figure 3 This is a Raman spectrum of randomly selected points characterizing the quasi-suspended graphene sample prepared in Example 1.

[0052] Figure 4 This is the SEM image of the quasi-suspended graphene prepared in Example 2.

[0053] Figure 5 AFM morphology and friction force (LFM) images of the quasi-suspended graphene prepared in Example 3. (a) Schematic diagram of AFM scanning sample; (b) morphology image, inset is random line scan data; (c) friction force (LFM) image, inset is random line scan data.

[0054] Figure 6 This is a graph showing the relationship between the mobility of the quasi-suspended graphene prepared in Example 4 and the temperature.

[0055] Figure 7 This is a graph showing the relationship between the transfer characteristic curve of the quasi-suspended graphene prepared in Example 1 and the temperature. DETAILED DESCRIPTION

[0056] The present invention is further described in detail below through specific examples. The following examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way.

[0057] Example 1

[0058] (1) Selecting two silicon carbide wafers, referred to as silicon carbide substrate A and silicon carbide substrate B, respectively; performing chemical mechanical polishing (CMP) on the silicon carbide substrate A and the silicon carbide substrate B, removing paraffin wax and thoroughly cleaning;

[0059] (2) ultrasonically treating silicon carbide substrate A and silicon carbide substrate B in acetone, anhydrous ethanol, and deionized water for 15-30 min, and then drying with N2;

[0060] (3) The C surface of the silicon carbide wafer A is covered with a carbon film, and the silicon carbide wafer B is not coated with a carbon film; wherein the carbon film can be prepared by high temperature decomposition, spin coating, physical evaporation and chemical plating;

[0061] (4) placing a silicon carbide wafer A coated with a carbon film and a silicon carbide wafer B not coated with a carbon film into a conventional graphite crucible; specifically, the silicon carbide wafer A at the bottom is stacked with the silicon carbide wafer B at the top, and the Si surface of the silicon carbide wafer A is opposite to the Si surface of the silicon carbide wafer B;

[0062] (5) Place the graphite crucible containing silicon carbide sheet A and silicon carbide sheet B into an induction heating furnace:

[0063] The first stage is to maintain the temperature in a vacuum environment at 900-950°C for 20-30 minutes;

[0064] The second stage is 400 sccm flowing argon, constant temperature 1250-1300°C for 20-30 min;

[0065] The third stage was 400 sccm flowing argon at 1605°C for 95 min;

[0066] (6) After furnace cooling, semiconductor graphene is obtained.

[0067] (7) The crucible containing the sample was placed in an induction heating furnace and annealed at 1000°C for 11 min in an 80 sccm H2 atmosphere.

[0068] (8) After cooling in a furnace, a sample is obtained.

[0069] Figure 3 This is the Raman spectrum of randomly selected points of the sample prepared in Example 1. Figure 7 The relationship between the transfer characteristic curve of the sample prepared in Example 1 and the temperature is shown, showing a centimeter-level room temperature ballistic transport free path.

[0070] Example 2

[0071] (1) Selecting two silicon carbide wafers, referred to as silicon carbide substrate A and silicon carbide substrate B, respectively; performing chemical mechanical polishing (CMP) on the silicon carbide substrate A and the silicon carbide substrate B, removing paraffin wax and thoroughly cleaning;

[0072] (2) ultrasonically treating silicon carbide substrate A and silicon carbide substrate B in acetone, anhydrous ethanol, and deionized water for 15-30 min, and then drying with N2;

[0073] (3) placing silicon carbide wafer A and silicon carbide wafer B into a conventional graphite crucible, specifically, the C surface of silicon carbide wafer A is opposite to the Si surface of silicon carbide wafer B;

[0074] (4) Place the crucible stacked with the silicon carbide substrate into an induction heating furnace:

[0075] The first stage is to maintain the temperature in a vacuum environment at 900-950°C for 20-30 minutes;

[0076] The second stage is 400 sccm flowing argon, constant temperature 1250-1300°C for 20-30 min;

[0077] The third stage was 400 sccm flowing argon at 1610 °C for 105 min;

[0078] (5) After furnace cooling, a sample is obtained.

[0079] (6) The crucible containing the sample was placed in an induction heating furnace and annealed at 900 °C for 15 min in a 90 sccm H2 atmosphere.

[0080] (7) After cooling in a furnace, a sample is obtained.

[0081] Figure 4 This is the SEM image of the sample prepared in Example 2.

[0082] Example 3

[0083] (1) Select a silicon carbide wafer as a silicon carbide substrate for chemical mechanical polishing (CMP), remove the paraffin wax and clean it thoroughly;

[0084] (2) ultrasonically treating the silicon carbide substrate in acetone, anhydrous ethanol, or deionized water for 15-30 min, and then drying it with N2;

[0085] (3) placing the silicon carbide sheet into a modified graphite crucible, wherein the modified graphite crucible is to change the outer surface of the bottom of the crucible from a curved surface to a flat surface;

[0086] (4) Place the modified graphite crucible containing the silicon carbide substrate into an induction heating furnace:

[0087] The first stage is to maintain the temperature in a vacuum environment at 900-950°C for 20-30 minutes;

[0088] The second stage is 400 sccm flowing argon, constant temperature 1250-1300°C for 20-30 min;

[0089] The third stage was 400 sccm flowing argon at 1700 °C for 80 min;

[0090] (5) After furnace cooling, a sample is obtained.

[0091] (6) Place the crucible containing the sample in an induction heating furnace at 100 sccmH 2 Anneal at 1100℃ for 30min in atmosphere.

[0092] (7) After cooling in a furnace, a sample is obtained.

[0093] Figure 5 AFM morphology and friction force (LFM) images of the sample prepared in Example 3. (a) Schematic diagram of AFM scanning of the sample; (b) morphology image, the inset is the random line scan data; (c) friction force (LFM) image, the inset is the random line scan data.

[0094] Example 4

[0095] The sample was prepared according to the steps of Example 1, except that the heating time in step (7) was 40 min.

[0096] Figure 6 This is a graph showing the relationship between the mobility of the sample prepared in Example 4 and the temperature.

[0097] Example 5

[0098] The sample was prepared according to the steps of Example 1, except that the heating time in step (7) was 80 min.

[0099] Example 6

[0100] The sample was prepared according to the steps of Example 1, except that the heating time in step (7) was 60 min.

[0101] Example 7

[0102] The sample preparation was carried out according to the steps of Example 2, except that the heating temperature in step (7) was 1200°C.

[0103] Example 8

[0104] The sample preparation was carried out according to the steps of Example 2, except that the heating temperature in step (7) was 1300°C.

[0105] Example 9

[0106] The sample preparation was carried out according to the steps of Example 3, with the only difference being that the hydrogen flow rate in step (7) was 90 sccm.

[0107] Example 10

[0108] The sample preparation was carried out according to the steps of Example 3, with the only difference being that the hydrogen flow rate in step (7) was 50 sccm.

[0109] The present invention discusses in detail the use of hydrogen intercalation to prepare quasi-suspended graphene directly on an insulating substrate. Considering that the mobility of general Si-surface graphene is relatively low due to the influence of factors such as the substrate's n-type doping, the steps and the double / triple-layer graphene strips at the steps as scattering sources, etc.; further, although it is easy to prepare single-layer graphene on the Si surface of SiC, Si-surface graphene is not continuous graphene, but is interspersed with double-layer and / or triple-layer graphene strips, the width (crystal domain size) of which does not exceed 10μm. Therefore, on the basis of growing ultra-large-area single-domain semiconductor graphene, further hydrogen intercalation is used to obtain a crystal domain width of more than 500μm and a room temperature mobility of up to 3300cm 2 / V·s, which is more than three times that of traditional Si-surface graphene.

[0110] Figure 1 This is a flow chart of the growth of quasi-free standing graphene of Example 1. Figure 2 It is a schematic diagram of the atomic structure of the quasi-free standing graphene of Example 1 (side view), wherein the yellow solid spheres represent Si atoms, the gray solid spheres represent C atoms, and the blue solid spheres represent H atoms.

[0111] In order to further characterize the uniformity of the single-crystal domain quasi-suspended graphene, Raman characterization was performed, and it can be seen that the quasi-suspended graphene has a high degree of uniformity, such as Figure 3 shown. Figure 4 This is a SEM image of quasi-suspended graphene. It can be seen from the image that its width can reach more than 200μm. In addition, AFM is used to characterize the uniformity of quasi-suspended graphene. Its morphology image and friction force image show that it has a high degree of uniformity, such as Figure 5 shown. Figure 6 The relationship between the Hall mobility and temperature of quasi-suspended graphene. It can be seen that its mobility has no dependence on temperature. Figure 7 The graph of the transfer characteristics of quasi-suspended graphene changing with temperature shows that the residual resistance is 1G 0 (G 0 The quasi-suspended graphene thus obtained has a room-temperature ballistic transport free path of centimeters.

[0112] The sample uniformity, domain quality, domain width and length, mobility and ballistic free path of ultra-large area single-domain quasi-suspended graphene prepared in the remaining embodiments within the protection scope of the present invention were studied, and similar results to those mentioned above were obtained.

[0113] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments, which are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms of specific changes without departing from the scope of protection of the present invention and the claims, all of which fall within the scope of protection of the present invention.

Claims

1. An ultra-large single-crystal domain quasi-suspended graphene, comprising a silicon carbide substrate, characterized in that: The Si surface of the silicon carbide substrate is prepared with uniformly grown quasi-suspended graphene, which is prepared from semiconductor graphene through hydrogen intercalation; the quasi-suspended graphene is a single layer, and its crystal domain width is greater than 200 microns and less than or equal to 500 microns, and its length is sub-centimeter level; the quasi-suspended graphene has a centimeter-level ballistic transport free path at room temperature.

2. The ultra-large single-crystal domain quasi-suspended graphene according to claim 1, characterized in that: The room temperature mobility of the quasi-suspended graphene is at least 3300 cm 2 / (V·s).

3. The ultra-large single-crystal domain quasi-suspended graphene according to claim 1, characterized in that: The quasi-suspended graphene is not bonded to the SiC substrate and has semi-metallic properties.

4. The ultra-large single-crystal domain quasi-suspended graphene according to claim 1, characterized in that: The silicon carbide substrate is 6H, 4H or 3C.

5. A method for preparing ultra-large single-crystal domain quasi-suspended graphene as claimed in any one of claims 1 to 4, characterized in that: The preparation process includes the following: (i) directly growing semiconductor graphene on the SiC substrate; the semiconductor graphene is a single layer and grows uniformly, the crystal domain width of the semiconductor graphene is greater than 200 microns and less than or equal to 500 microns, the length is sub-centimeter level, and the room temperature mobility is at least 4500cm 2 / (V·s); the semiconductor graphene is obtained by one of the three methods A, B and C; (ii) preparing the semiconductor graphene into quasi-suspended graphene by hydrogen intercalation; Wherein, in method A of step (i), the semiconductor graphene is obtained according to the following steps: (1) Pre-treating two SiC substrates, and then preparing a carbon film on the C surface of one of the SiC substrates; (2) stacking two SiC substrates and placing them in a crucible, with the Si surfaces of the two SiC substrates facing each other; (3) annealing the crucible stacked with two SiC substrates at 900-950 °C for 20-30 min under vacuum conditions to clean the SiC substrates; (4) heating the crucible with two stacked SiC substrates at 1250-1300 °C for 20-30 min in an argon atmosphere; heating the SiC substrates in an argon atmosphere to perform preliminary morphology bunching; (5) The crucible stacked with two SiC substrates is further heated at 1560° C.-1700° C. in an argon atmosphere to grow semiconductor graphene for 50-600 min, thereby obtaining semiconductor graphene on both SiC substrates; Wherein, in method B of step (I), the semiconductor graphene is obtained according to the following steps: (1) taking two SiC substrates for pretreatment, wherein neither of the two SiC substrates is provided with a carbon film; (2) stacking two SiC substrates and placing them in a crucible, with the C surfaces of the two SiC substrates facing the Si surfaces; (3) annealing the crucible stacked with two SiC substrates at 900-950 °C for 20-30 min under vacuum conditions to clean the SiC substrates; (4) heating the crucible with two stacked SiC substrates at 1250-1300 °C for 20-30 min in an argon atmosphere; heating the SiC substrates in an argon atmosphere to perform preliminary morphology bunching; (5) further heating the crucible stacked with two SiC substrates at 1560° C.-1700° C. in an argon atmosphere to grow semiconductor graphene for 50-600 min, thereby obtaining semiconductor graphene on a SiC substrate; Wherein, in method C of step (I), the semiconductor graphene is obtained according to the following steps: (1) Pre-treating a SiC substrate and placing it in a modified crucible, wherein the structure of the modified crucible is that the outer surface of the bottom is changed from a curved surface to a flat surface; (2) annealing the modified crucible with a SiC substrate at 900-950 °C for 20-30 min under vacuum conditions to clean the SiC substrate; (3) heating the modified crucible with a SiC substrate in an argon atmosphere at 1250-1300 °C for 20-30 min; heating the SiC substrate in an argon atmosphere to perform preliminary morphology focusing; (4) The modified crucible with a SiC substrate placed thereon is further heated at 1560° C.-1700° C. in an argon atmosphere for 50-600 min to grow semiconductor graphene, thereby obtaining semiconductor graphene on the SiC substrate.

6. The method for preparing the ultra-large single-crystal domain quasi-suspended graphene according to claim 5, characterized in that: The quasi-suspended graphene is prepared by hydrogen intercalation, and the semiconductor graphene is heated at 900-1300° C. for 10-80 minutes in a hydrogen atmosphere.

7. The method for preparing the ultra-large single-crystal domain quasi-suspended graphene according to claim 5, characterized in that: The hydrogen flow rate of the hydrogen atmosphere is 50-100 sccm.

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