A semiconductor graphene-quasi-suspended graphene all-carbon structure and preparation method thereof

Abstract

The present invention belongs to the technical field of carbon-based devices, and discloses a semiconductor graphene-quasi-suspended graphene all-carbon structure and a preparation method thereof. Semiconductor graphene is first prepared on the surface of a SiC substrate; then, in a local area of ​​the semiconductor graphene, quasi-suspended graphene is prepared by hydrogen intercalation, electron beam direct writing, focused ion beam, laser induction or atomic force microscope tip heating. The above-mentioned semiconductor graphene and quasi-suspended graphene are both single-layer, and form a seamlessly overlapped continuous whole on the plane; the quasi-suspended graphene can be used as an electrode part, and the semiconductor graphene can be used as a channel material. The present invention can directly grow a single-layer single-crystal semiconductor graphene on an insulating substrate, which has an ultra-large crystal domain and ultra-high room temperature high mobility; and on this basis, a quasi-suspended graphene-semiconductor graphene all-carbon structure is directly obtained by a variety of means, in the expectation of using the structure to prepare all-carbon devices and integrated circuits with excellent performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon-based devices, and in particular, relates to a full-carbon structure and a preparation method thereof. Background Art

[0002] At the beginning of this century, carbon-based devices and all-carbon integrated circuits gradually attracted the attention of researchers around the world, and carbon-based electronics gradually became a new field that could replace silicon-based COMS technology. Compared with silicon-based materials, carbon-based semiconductors have the advantages of lower cost, lower power consumption and higher efficiency; and all-carbon circuits have strong tolerance to harsh environments and excellent radiation resistance. Compared with silicon-based circuits, they can meet the needs of different application functions and scenarios.

[0003] Among the existing carbon-based materials, graphene has advantages in connection positioning and patterning due to its unique two-dimensional material morphology, and is compatible with traditional semiconductor planar preparation processes when building devices; in addition, graphene has high carrier saturation velocity, high carrier mobility and excellent thermal conductivity, so it is expected to become a substitute for silicon-based materials in the field of integrated circuits. Since graphene has no band gap, it is difficult to use in logic circuits, which limits its application in the semiconductor field. The preparation of graphene-based all-carbon devices and integrated circuits requires the use of complex processes to open the band gap of graphene, or the growth of other conductive carbon materials as functional parts, which increases the difficulty of preparing all-carbon devices and integrated circuits.

[0004] Graphene is a two-dimensional material made of carbon atoms, while graphite consists of multiple layers of graphene. Single layers of graphene can be peeled off from graphite and have electronic properties similar to those of graphite. Graphene is a semimetal, neither a metal nor a semiconductor, and can be described as a semiconductor without a band gap (Wallace 1947). The electronic properties of graphene are now well understood, with high electron mobility and good electrical conductivity, making it a promising two-dimensional electronic material for a wide range of applications. However, due to the lack of a band gap, graphene cannot be used in conventional digital electronics, i.e. it cannot be switched on and off by applying an electric field, which is required for electronics in conventional semiconductors such as silicon. Although various schemes have been discovered to "modify" graphene so that it has a band gap, for example by creating narrow graphene ribbons (Han 2010) or by chemically modifying the properties of graphene (Elias 2009), these "modifications" severely degrade its electrical properties, so that so far, no effective method has been found to produce semiconducting graphene with semiconducting properties while taking into account high mobility (Schwierz 2015).

[0005] It has also been found that when silicon carbide is heated to above 1000°C in an inert atmosphere, graphene forms on its surface. This form of graphene is called epitaxial graphene (van Bommel, 1975). Van Bommel also found that when the silicon face of hexagonal polycrystalline silicon carbide is heated to above 1000°C in a vacuum, its surface becomes graphitized (van Bommel, 1975). Graphitization occurs because silicon sublimates from the surface at high temperatures and the surface is covered with carbon atoms. At high temperatures, the carbon atoms react chemically and cover the surface of the silicon carbide in the form of silicon-carbon bonds. This form of graphene is called a buffer layer. Subsequent studies have shown that due to the presence of silicon-carbon bonds, the buffer layer does not have the intrinsic electrical properties of graphene, but is an insulator (Emtsev, 2008). In subsequent studies, an optimized high-temperature annealing method, the so-called confinement-controlled sublimation method (de Heer in 2011), was used to control the sublimation of silicon from the SiC surface. The electronic structure measurements showed that the electronic structure of this buffer layer does have a semiconductor band gap (Nair in 2017), but the measurement of its electronic performance in electronic devices showed that the electron mobility was very low (Turmaud in 2018), which was due to the disorder of the binding between the buffer layer and the SiC surface. In addition, the measurements also showed that a considerable part of the buffer layer was "contaminated" by graphene, which was caused by the graphene strips "decorated" on the atomic steps of the SiC surface. Therefore, the buffer layer produced by the CCS method (Nevius in 2015) is not suitable for electronics. Due to the bunching effect on the silicon surface during the growth of the buffer layer, its morphology is stepped, that is, the alternating morphology of step-terrace-step, which will restrict the size of the crystal domain and affect its transport properties. Summary of the invention

[0006] The present invention aims to overcome the complex and expensive preparation process of existing all-carbon devices and integrated circuits, as well as technical problems such as contact caused by overlapping metal electrodes, and provides a semiconductor graphene-quasi-suspended graphene all-carbon structure and a preparation method thereof, which can directly grow a single-layer single-crystal semiconductor graphene on an insulating substrate, which has an ultra-large crystal domain and ultra-high room temperature high mobility; and on this basis, a quasi-suspended graphene-semiconductor graphene all-carbon structure is directly obtained by various means, in the hope of using this structure to prepare all-carbon devices and integrated circuits with excellent performance.

[0007] In order to solve the above technical problems, the present invention is implemented by the following technical solutions:

[0008] According to one aspect of the present invention, there is provided a semiconductor graphene-quasi-suspended graphene all-carbon structure, comprising a silicon carbide substrate, wherein the Si surface of the silicon carbide substrate is prepared with semiconductor graphene and quasi-suspended graphene; the semiconductor graphene and the quasi-suspended graphene are both single-layered, and form a seamlessly overlapped continuous whole on a plane; the quasi-suspended graphene can be used as an electrode part, and the semiconductor graphene can be used as a channel material.

[0009] Furthermore, the semiconductor graphene has a graphene lattice structure, is partially bonded to the SiC substrate, and has a band gap.

[0010] Furthermore, the semiconductor graphene grows uniformly, its crystal domain width is greater than 200 microns, its length is sub-centimeter level, and its room temperature mobility reaches at least 4500cm 2 / (V·s).

[0011] Furthermore, the silicon carbide substrate is 6H, 4H or 3C.

[0012] According to another aspect of the present invention, a method for preparing the above-mentioned semiconductor graphene-quasi-suspended graphene all-carbon structure is provided, comprising the following preparation process:

[0013] (1) preparing the semiconductor graphene on the surface of the SiC substrate;

[0014] (ii) preparing quasi-suspended graphene in a local area of ​​the semiconductor graphene obtained in step (i), wherein the quasi-suspended graphene is prepared by one of hydrogen intercalation, electron beam direct writing, focused ion beam, laser induction and atomic force microscope tip heating.

[0015] Furthermore, the semiconductor graphene can be obtained by the following three methods:

[0016] A: The first method for preparing the semiconductor graphene is carried out according to the following steps:

[0017] (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;

[0018] (2) stacking two SiC substrates and placing them in a crucible, with the Si surfaces of the two SiC substrates facing each other;

[0019] (3) annealing the crucible stacked with two SiC substrates under vacuum conditions to clean the SiC substrates;

[0020] (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;

[0021] (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.

[0022] Preferably, the pretreatment in step (1) is to perform mechanical and chemical polishing on the two SiC substrates, followed by ultrasonic cleaning and N2 drying.

[0023] 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.

[0024] Preferably, the annealing temperature under vacuum conditions in step (3) is 900-950° C. and the time is 20-30 min.

[0025] Preferably, the temperature of heating the SiC substrate in step (4) is 1250-1300° C., and the heating time is 20-30 min.

[0026] 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.

[0027] B: The second method for preparing the semiconductor graphene is carried out according to the following steps:

[0028] (1) Take two SiC substrates for pretreatment;

[0029] (2) stacking two SiC substrates and placing them in a crucible, with the C surfaces of the two SiC substrates facing the Si surfaces;

[0030] (3) annealing the crucible stacked with two SiC substrates under vacuum conditions to clean the SiC substrates;

[0031] (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;

[0032] (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.

[0033] Preferably, the pretreatment in step (1) is to perform mechanical and chemical polishing on the two SiC substrates, followed by ultrasonic cleaning and N2 drying.

[0034] Preferably, the annealing temperature under vacuum conditions in step (3) is 900-950° C. and the time is 20-30 min;

[0035] Preferably, the temperature of heating the SiC substrate in step (4) is 1250-1300° C., and the heating time is 20-30 min.

[0036] 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.

[0037] C: The third method for preparing the semiconductor graphene is carried out according to the following steps:

[0038] (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;

[0039] (2) annealing the modified crucible stacked with two SiC substrates under vacuum conditions to clean the SiC substrates;

[0040] (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;

[0041] (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.

[0042] Preferably, the pretreatment in step (1) is to perform mechanical and chemical polishing on the two SiC substrates, followed by ultrasonic cleaning and N2 drying.

[0043] Preferably, the annealing temperature under vacuum conditions in step (3) is 900-950° C. and the time is 20-30 min;

[0044] Preferably, the temperature of heating the SiC substrate in step (4) is 1250-1300° C., and the heating time is 20-30 min.

[0045] 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.

[0046] Furthermore, when the quasi-suspended graphene is prepared by hydrogen intercalation, it is obtained according to the following steps:

[0047] (1) spin coating a photoresist on the surface of the semiconductor graphene;

[0048] (2) patterning the spin-coated photoresist using photolithography;

[0049] (3) depositing a dielectric layer on the patterned semiconductor graphene surface;

[0050] (4) stripping the photoresist from the semiconductor graphene deposited with the dielectric layer to obtain a patterned dielectric layer; that is, part of the semiconductor graphene surface is covered with the dielectric layer, and the rest of the semiconductor graphene surface is not covered with the dielectric layer;

[0051] (5) The semiconductor graphene covered with the patterned dielectric layer is heated in a hydrogen atmosphere to obtain a semiconductor graphene-quasi-suspended graphene all-carbon structure.

[0052] Furthermore, the dielectric layer is made of one of Al2O3, HfO2, Y2O3 and SiO2.

[0053] Furthermore, the deposition method is one of atomic layer deposition, electron beam evaporation and magnetron sputtering.

[0054] Preferably, in step (5), the hydrogen flow rate is 50-100 sccm.

[0055] Preferably, the heating temperature in step (5) is 500-1100°C.

[0056] Preferably, the heating time in step (5) is 5-60 min.

[0057] Furthermore, when the quasi-suspended graphene is prepared by laser induction, the laser power used is 520-1500 mJ.

[0058] Furthermore, when the quasi-suspended graphene is prepared by heating the atomic force microscope tip, the tip is one of an atomic force microscope tip, a scanning tunneling microscope tip and a multi-probe scanning tip; and the heating temperature of the atomic force microscope tip is 500-900°C.

[0059] The beneficial effects of the present invention are:

[0060] (I) The semiconductor graphene-quasi-suspended graphene all-carbon structure and preparation method thereof of the present invention successfully obtain a semiconductor graphene-quasi-suspended graphene plane seamless overlapping structure; wherein the quasi-suspended graphene has no interaction with the SiC substrate (interaction refers to bonding with the SiC substrate), retaining the inherent properties of graphene itself with semi-metallic properties, thereby serving as an electrode part; wherein the semiconductor graphene is partially bonded with the SiC substrate, the symmetry is broken, and the band gap is opened, thereby serving as a channel material; more importantly, the graphene as the electrode and the graphene as the channel are seamlessly connected, so that the contact resistance can be ignored, which is expected to completely solve the problem of overlapping metal electrodes with two-dimensional materials.

[0061] (ii) The semiconductor graphene-quasi-suspended graphene all-carbon structure and preparation method thereof of the present invention, the obtained semiconductor graphene is a single layer and grows uniformly, with an ultra-large single crystal domain (the width of the crystal domain is greater than 200 microns, and the optimal width can reach 500 microns); at the same time, the semiconductor graphene has a high on-off ratio (up to 10 4 ), quasi-suspended graphene has a high mobility (up to 3000cm 2 / (V·S)), thus combining the advantages of semiconductor graphene and quasi-suspended graphene, achieving seamless connection between electrode (quasi-suspended graphene) and channel (semiconductor graphene), thus eliminating the technical difficulty of device performance affected by "contact".

[0062] (III) The semiconductor graphene-quasi-suspended graphene all-carbon structure and preparation method thereof of the present invention can be prepared directly on the Si surface of the insulating substrate silicon carbide, without the need for transfer operation, thereby avoiding damage and contamination of the sample during the transfer process, which can save costs and simplify production steps in practical applications.

[0063] (iv) The semiconductor graphene-quasi-suspended graphene all-carbon structure and its preparation method of the present invention can be used to prepare all-carbon devices and all-carbon integrated circuits, thereby solving the problems of poor performance and high power consumption of device miniaturization caused by the small size effect, which opens up an important channel in the field of device miniaturization and environmental friendliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 It is a schematic diagram of the structure of the quasi-suspended graphene-semiconductor graphene prepared in Example 1 of the present invention.

[0065] Figure 2 This is a Raman image of the structure of the quasi-suspended graphene-semiconductor graphene prepared in Example 1 of the present invention.

[0066] Figure 3 This is a SEM image of the structure of the quasi-suspended graphene-semiconductor graphene prepared in Example 1 of the present invention.

[0067] Figure 4 It is a device output characteristic curve diagram of the quasi-suspended graphene-semiconductor graphene prepared in Example 1 of the present invention.

[0068] Figure 5 This is a SEM image of the structure of the quasi-suspended graphene-semiconductor graphene prepared in Example 14 of the present invention.

[0069] Figure 6 This is a SEM image of the structure of the quasi-suspended graphene-semiconductor graphene prepared in Example 16 of the present invention. DETAILED DESCRIPTION

[0070] 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.

[0071] Example 1

[0072] Semiconductor graphene is grown directly on the Si surface of the SiC substrate. The specific steps are as follows:

[0073] (1) Selecting two silicon carbide wafers, referred to as silicon carbide substrate A and silicon carbide substrate B;

[0074] (2) The silicon carbide substrate A and the silicon carbide substrate B were ultrasonically treated in acetone, anhydrous ethanol, and deionized water, and then dried with N2;

[0075] (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 one of pyrolysis, spin coating, physical evaporation and chemical plating;

[0076] (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;

[0077] (5) Alternatively, a silicon carbide wafer A and a silicon carbide wafer B, both of which are not coated with a carbon film, are placed in a conventional graphite crucible. Specifically, the C surface of the silicon carbide wafer A is opposite to the Si surface of the silicon carbide wafer B.

[0078] (6) Alternatively, a silicon carbide wafer is selected and placed in a modified graphite crucible, wherein the modified graphite crucible is a bottom outer surface of the crucible that is changed from a curved surface to a flat surface;

[0079] (7) Place the graphite crucible containing the silicon carbide sheet into an induction heating furnace:

[0080] The first stage is to maintain the temperature in a vacuum environment at 900-950°C for 20-30 minutes;

[0081] The second stage is 400 sccm flowing argon, constant temperature 1250-1300°C for 20-30 min;

[0082] The third stage is 400 sccm flowing argon, maintained at 1560-1700°C for 50-600 min;

[0083] (8) After furnace cooling, semiconductor graphene is obtained.

[0084] The steps for preparing semiconductor graphene-quasi-suspended graphene all-carbon structure are as follows:

[0085] (9) Spin coating photoresist on the prepared semiconductor graphene surface:

[0086] (10) patterning the spin-coated photoresist using photolithography, which is performed in a photolithography machine;

[0087] (11) depositing an Al2O3 dielectric layer on the patterned semiconductor graphene surface by atomic layer deposition;

[0088] (12) placing the semiconductor graphene with the dielectric layer deposited thereon in an organic solvent and peeling it off to obtain a patterned dielectric layer; that is, part of the semiconductor graphene surface is covered with the dielectric layer, and the rest of the semiconductor graphene surface is not covered with the dielectric layer;

[0089] (13) Finally, the mixture was placed in a hydrogen atmosphere and heated at a hydrogen flow rate of 80 sccm, a heating temperature of 1000°C, and a heating time of 11 min to obtain a semiconductor graphene-quasi-suspended graphene all-carbon structure. In the structure, both the semiconductor graphene and the quasi-suspended graphene are single layers and form a seamlessly overlapped continuous whole on the plane, such as Figure 1 and Figure 2 shown.

[0090] Figure 2 This is the Raman image of the quasi-suspended graphene-semiconductor graphene structure prepared in Example 1. It can be clearly seen that there is a clear boundary between the distribution of the quasi-suspended graphene and the semiconductor graphene, and both are uniform without other impurities.

[0091] Figure 3 This is a SEM image of the quasi-suspended graphene-semiconductor graphene structure prepared in Example 1. It can be seen from the image that the dark contrast portion is the quasi-suspended graphene, and the light contrast portion is the semiconductor graphene.

[0092] Figure 4 This is the device performance diagram of the quasi-suspended graphene-semiconductor graphene structure prepared in Example 1. It can be seen that the device reaches 10 4 The above switch ratio.

[0093] Example 2

[0094] The method of Example 1 was used to prepare the semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the deposited dielectric layer in step (11) was HfO2. A seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0095] Example 3

[0096] The method of Example 1 was used to prepare the semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the deposited dielectric layer in step (11) was Y2O3. A seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0097] Example 4

[0098] The method of Example 1 was used to prepare the semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the deposited dielectric layer in step (11) was SiO2. A seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0099] Example 5

[0100] The method of Example 1 was used to prepare the semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the deposition method in step (11) was electron beam evaporation. A seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0101] Example 6

[0102] The method of Example 1 was used to prepare the semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the deposition method in step (11) was magnetron sputtering. A seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0103] Example 7

[0104] The method of Example 1 was used to prepare a semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the hydrogen flow rate in step (13) was 50 sccm; a seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared.

[0105] Example 8

[0106] The method of Example 1 was used to prepare a semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the hydrogen flow rate in step (13) was 100 sccm; a seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared.

[0107] Example 9

[0108] The method of Example 1 was used to prepare a semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the heating temperature in step (13) was 500° C.; a seamless quasi-suspended graphene-semiconductor graphene structure was successfully prepared, but the graphene D peak was high and the quality was poor.

[0109] Example 10

[0110] The method of Example 1 was used to prepare a semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the heating temperature in step (13) was 1000° C.; a seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared.

[0111] Embodiment 11

[0112] The method of Example 1 was used to prepare a semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the heating time in step (13) was 5 minutes; a seamless quasi-suspended graphene-semiconductor graphene structure was successfully prepared, but the graphene D peak was high and the quality was poor.

[0113] Example 12

[0114] The semiconductor graphene-quasi-suspended graphene all-carbon structure was prepared using the method of Example 1, the only difference being that the heating time in step (13) was 60 min; a seamless quasi-suspended graphene-semiconductor graphene junction was successfully prepared.

[0115] Embodiment 13

[0116] The semiconductor graphene-quasi-suspended graphene all-carbon structure was prepared using the method of Example 1, the only difference being that the heating time in step (13) was 30 minutes; a seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0117] Embodiment 14

[0118] Semiconductor graphene is grown directly on the Si surface of the SiC substrate. The specific steps are as follows:

[0119] (1) Selecting two silicon carbide wafers, referred to as silicon carbide substrate A and silicon carbide substrate B;

[0120] (2) The silicon carbide substrate A and the silicon carbide substrate B were ultrasonically treated in acetone, anhydrous ethanol, and deionized water, and then dried with N2;

[0121] (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;

[0122] (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;

[0123] (5) Alternatively, a silicon carbide wafer A and a silicon carbide wafer B, both of which are not coated with a carbon film, are placed in a conventional graphite crucible. Specifically, the C surface of the silicon carbide wafer A is opposite to the Si surface of the silicon carbide wafer B.

[0124] (6) Alternatively, a silicon carbide wafer is selected and placed in a modified graphite crucible, wherein the modified graphite crucible is a bottom outer surface of the crucible that is changed from a curved surface to a flat surface;

[0125] (7) Place the graphite crucible containing the silicon carbide sheet into an induction heating furnace:

[0126] The first stage is to maintain the temperature in a vacuum environment at 900-950°C for 20-30 minutes;

[0127] The second stage is 400 sccm flowing argon, constant temperature 1250-1300°C for 20-30 min;

[0128] The third stage is 400 sccm flowing argon, maintained at 1560-1700°C for 50-600 min;

[0129] (8) After furnace cooling, semiconductor graphene is obtained.

[0130] The steps for preparing semiconductor graphene-quasi-suspended graphene all-carbon structure are as follows:

[0131] (9) The prepared semiconductor graphene is subjected to local laser induction with a laser power of 520 mJ and a time of 5 min to obtain a semiconductor graphene-quasi-suspended graphene full-carbon structure.

[0132] Figure 5 This is a SEM image of the quasi-suspended graphene-semiconductor graphene structure prepared in Example 14. It can be seen from the image that the dark contrast portion is the quasi-suspended graphene, and the light contrast portion is the semiconductor graphene.

[0133] Embodiment 15

[0134] The method of Example 14 is used to prepare a semiconductor graphene-quasi-suspended graphene full-carbon structure, the only difference being that when the prepared semiconductor graphene is laser induced, a laser power of 1200mJ is used to obtain a semiconductor graphene-quasi-suspended graphene full-carbon structure.

[0135] Example 16

[0136] Semiconductor graphene is grown directly on the Si surface of the SiC substrate. The specific steps are as follows:

[0137] (1) Selecting two silicon carbide wafers, referred to as silicon carbide substrate A and silicon carbide substrate B;

[0138] (2) The silicon carbide substrate A and the silicon carbide substrate B were ultrasonically treated in acetone, anhydrous ethanol, and deionized water, and then dried with N2;

[0139] (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;

[0140] (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;

[0141] (5) Alternatively, a silicon carbide wafer A and a silicon carbide wafer B, both of which are not coated with a carbon film, are placed in a conventional graphite crucible. Specifically, the C surface of the silicon carbide wafer A is opposite to the Si surface of the silicon carbide wafer B.

[0142] (6) Alternatively, a silicon carbide wafer is selected and placed in a modified graphite crucible, wherein the modified graphite crucible is a bottom outer surface of the crucible that is changed from a curved surface to a flat surface;

[0143] (7) Place the graphite crucible containing the silicon carbide sheet into an induction heating furnace:

[0144] The first stage is to maintain the temperature in a vacuum environment at 900-950°C for 20-30 minutes;

[0145] The second stage is 400 sccm flowing argon, constant temperature 1250-1300°C for 20-30 min;

[0146] The third stage is 400 sccm flowing argon, maintained at 1560-1700°C for 50-600 min;

[0147] (8) After furnace cooling, semiconductor graphene is obtained.

[0148] The steps for preparing semiconductor graphene-quasi-suspended graphene all-carbon structure are as follows:

[0149] (9) The prepared semiconductor graphene is locally scanned by atomic force microscope tip heating, the tip is an atomic force microscope tip, the heating temperature is 900° C., the heating time is 5 min, the hydrogen purity is 99.9999%, the hydrogen flow rate is 80 sccm, and a semiconductor graphene-quasi-suspended graphene full carbon structure is obtained.

[0150] Figure 6 This is a SEM image of the quasi-suspended graphene-semiconductor graphene structure prepared in Example 16. It can be seen from the image that the dark contrast portion is the quasi-suspended graphene, and the light contrast portion is the semiconductor graphene.

[0151] Embodiment 17

[0152] The method of Example 16 was used to prepare a semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that when the prepared semiconductor graphene was heated by an atomic force microscope tip, the tip was a scanning tunneling microscope tip. A seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0153] Embodiment 18

[0154] The method of Example 16 was used to prepare the semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that when the prepared semiconductor graphene was heated by an atomic force microscope tip, the tip was a NanoFrazor scanning tip. A seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0155] Embodiment 19

[0156] The method of Example 16 was used to prepare the semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the prepared semiconductor graphene was heated by the tip of an atomic force microscope at a heating temperature of 700° C. A seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0157] Embodiment 20

[0158] The method of Example 16 was used to prepare the semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the prepared semiconductor graphene was heated by the atomic force microscope tip at a heating temperature of 500° C. A seamless quasi-suspended graphene-semiconductor graphene structure was successfully prepared, but the graphene D peak was high and the quality was poor.

[0159] Embodiment 21

[0160] The method of Example 16 was used to prepare the semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that the prepared semiconductor graphene was heated by the atomic force microscope tip for 1 min. A seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0161] Embodiment 22

[0162] The method of Example 16 was used to prepare the semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that when the prepared semiconductor graphene was heated by the atomic force microscope tip, the hydrogen flow rate was 50 sccm. A seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0163] Embodiment 23

[0164] The method of Example 16 was used to prepare the semiconductor graphene-quasi-suspended graphene all-carbon structure, the only difference being that when the prepared semiconductor graphene was heated by the atomic force microscope tip, the hydrogen flow rate was 100 sccm. A seamlessly connected quasi-suspended graphene-semiconductor graphene structure was successfully prepared, and each part had a high degree of uniformity.

[0165] 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. A semiconductor graphene-quasi-suspended graphene all-carbon structure, comprising a silicon carbide substrate, characterized in that: The Si surface of the silicon carbide substrate is prepared with semiconductor graphene and quasi-suspended graphene; the semiconductor graphene is directly grown on the Si surface of the silicon carbide substrate; the semiconductor graphene grows uniformly, its crystal domain width is greater than 200 microns, its length is sub-centimeter level, and its room temperature mobility reaches at least 4500cm 2 / (V·s); the semiconductor graphene has a graphene lattice structure, is partially bonded to the SiC substrate, and has a band gap; the semiconductor graphene and the quasi-suspended graphene are both single-layer, and form a seamlessly overlapped continuous whole on a plane; the quasi-suspended graphene can be used as an electrode part, and the semiconductor graphene can be used as a channel material.

2. The semiconductor graphene-quasi-suspended graphene all-carbon structure according to claim 1, characterized in that: The silicon carbide substrate is 6H, 4H or 3C.

3. A method for preparing a semiconductor graphene-quasi-suspended graphene all-carbon structure as claimed in any one of claims 1 to 2, characterized in that: The preparation process includes the following: (i) directly growing the semiconductor graphene on the surface of the SiC substrate; the semiconductor graphene is obtained according to one of the three methods A, B, and C; (ii) preparing quasi-suspended graphene in a local area of ​​the semiconductor graphene obtained in step (i), wherein the quasi-suspended graphene is prepared by one of hydrogen intercalation, electron beam direct writing, focused ion beam, laser induction and atomic force microscope tip heating; 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 in an argon atmosphere; heating the SiC substrates at 1250-1300 °C for 20-30 min 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 a modified graphite crucible containing a SiC substrate at 900-950 °C for 20-30 min under vacuum conditions to clean the SiC substrate; (3) heating a modified graphite crucible containing a SiC substrate at 1250-1300 °C for 20-30 min in an argon atmosphere; heating the SiC substrate in an argon atmosphere to perform preliminary morphology focusing; (4) The modified graphite 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.

4. The method for preparing the semiconductor graphene-quasi-suspended graphene all-carbon structure according to claim 3, characterized in that: When the quasi-suspended graphene is prepared by hydrogen intercalation, it is obtained according to the following steps: (1) spin coating a photoresist on the surface of the semiconductor graphene; (2) patterning the spin-coated photoresist using photolithography; (3) depositing a dielectric layer on the patterned semiconductor graphene surface; (4) stripping the photoresist from the semiconductor graphene deposited with the dielectric layer to obtain a patterned dielectric layer; that is, part of the surface of the semiconductor graphene is covered with the dielectric layer, and the rest of the surface of the semiconductor graphene is not covered with the dielectric layer; (5) The semiconductor graphene covered with the patterned dielectric layer is heated in a hydrogen atmosphere to obtain a semiconductor graphene-quasi-suspended graphene all-carbon structure.

5. The method for preparing the semiconductor graphene-quasi-suspended graphene all-carbon structure according to claim 4, characterized in that: The quasi-suspended graphene is prepared by heating using one of an atomic force microscope tip, a scanning tunneling microscope tip and a multi-probe scanning tip.

Images