Preparation method of quasi-suspended graphene, quasi-suspended graphene and field effect transistor

Abstract

The present invention provides a method for preparing quasi-suspended graphene, quasi-suspended graphene, and a field-effect transistor, which can be applied to the field of graphene technology. The method for preparing quasi-suspended graphene includes: placing semiconductor graphene epitaxially grown on a silicon carbide substrate into an annealing furnace, and evacuating the air from the annealing furnace until the gas pressure in the annealing furnace drops to a first predetermined pressure range; filling the annealing furnace within the first predetermined pressure range with nitrogen or an inert gas until the nitrogen or inert gas pressure in the annealing furnace rises to a second predetermined pressure range; and annealing the semiconductor graphene in a nitrogen or inert gas atmosphere, and converting the semiconductor graphene into quasi-suspended graphene by adjusting at least one parameter of the annealing temperature, annealing duration, and gas flow rate.

Description

Technical Field

[0001] The present invention relates to the technical field of graphene, and in particular to a preparation method of quasi-suspended graphene, the quasi-suspended graphene and a field effect transistor. Background Art

[0002] The emergence of semiconducting graphene has accelerated the development of graphene electronics and paved a new path for the future of graphene. Semiconducting graphene can be transformed into quasi-suspended graphene. Currently, hydrogen is typically used to intercalate semiconducting graphene at temperatures above 860°C (e.g., 1200°C) to form quasi-suspended graphene. However, hydrogen is inherently flammable and explosive. If a hydrogen storage leak occurs, accumulation to a certain concentration, and the presence of sparks or other triggering factors, an explosion could occur, potentially harming personnel and equipment, posing a low safety risk. Summary of the Invention

[0003] In view of the above problems, the present invention provides a method for preparing quasi-suspended graphene, quasi-suspended graphene and a field-effect transistor.

[0004] One aspect of the present application provides a method for preparing quasi-suspended graphene, comprising: placing semiconductor graphene epitaxially grown on a silicon carbide substrate into an annealing furnace, and extracting the air in the annealing furnace until the gas pressure in the annealing furnace drops to a first predetermined pressure range; filling nitrogen or an inert gas into the annealing furnace within the first predetermined pressure range until the pressure of the nitrogen or inert gas in the annealing furnace rises to a second predetermined pressure range; annealing the semiconductor graphene in the nitrogen or inert gas atmosphere, and converting the semiconductor graphene into quasi-suspended graphene by adjusting at least one parameter among the annealing temperature, annealing time, and gas flow rate.

[0005] According to an embodiment of the present invention, the inert gas includes at least one of helium, neon, argon, krypton, xenon and radon.

[0006] According to an embodiment of the present invention, the annealing temperature is between 400° C. and 850° C.

[0007] According to an embodiment of the present invention, the annealing time is between 10 minutes and 60 minutes.

[0008] According to an embodiment of the present invention, the gas flow rate is between 50 sccm and 500 sccm.

[0009] According to an embodiment of the present invention, the first predetermined pressure range includes 10 -5 Pa ~10 -6 Pa; the second predetermined pressure range includes 1Pa ~10 3 Pa.

[0010] According to an embodiment of the present invention, the annealing furnace is equipped with an inlet valve for introducing the nitrogen or inert gas, and an exhaust valve for exhausting the nitrogen or inert gas.

[0011] According to an embodiment of the present invention, the above-mentioned annealing of the semiconductor graphene in the above-mentioned nitrogen or inert gas atmosphere includes: during the annealing of the above-mentioned semiconductor graphene, the above-mentioned intake valve and the above-mentioned exhaust valve are both in the open state, and when the pressure of the nitrogen or inert gas introduced through the above-mentioned intake valve rises to the second predetermined pressure range, the above-mentioned semiconductor graphene is annealed; or during the annealing of the above-mentioned semiconductor graphene, the above-mentioned exhaust valve is in the closed state, and when the pressure of the above-mentioned nitrogen or inert gas introduced through the above-mentioned intake valve rises to the above-mentioned second predetermined pressure range, the above-mentioned intake valve is closed, and the semiconductor graphene is annealed.

[0012] Another aspect of the present invention further provides a quasi-suspended graphene, which is prepared using the above-mentioned method for preparing quasi-suspended graphene.

[0013] Another aspect of the present invention provides a field effect transistor using the above-mentioned quasi-suspended graphene as a channel material.

[0014] According to the method for preparing quasi-suspended graphene provided by an embodiment of the present invention, quasi-suspended graphene can be obtained by annealing semiconductor graphene. A chemically stable gas (nitrogen or inert gas) is used during annealing. As embedded atoms such as N or Ar saturate the silicon dangling bonds on the surface of silicon carbide (SiC), the semiconductor graphene can be completely separated from the substrate and transformed into independent graphene. This process does not require the use of flammable and explosive hydrogen, reducing the risk and improving the safety of preparing quasi-suspended graphene. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The flowchart of the method for preparing quasi-suspended graphene according to an embodiment of the present invention is schematically shown;

[0016] Figure 2A shows a structural diagram of semiconductor graphene under a scanning electron microscope according to an embodiment of the present invention;

[0017] Figure 2B shows a structural diagram of quasi-suspended graphene under a scanning electron microscope according to an embodiment of the present invention;

[0018] Figure 3A shows a graph showing Raman test results of semiconductor graphene according to an embodiment of the present invention;

[0019] Figure 3B shows a Raman test result diagram of quasi-suspended graphene according to an embodiment of the present invention;

[0020] Figure 4A shows a result diagram of quasi-suspended graphene under a scanning tunneling microscope according to an embodiment of the present invention;

[0021] Figure 4B shows a scanning tunneling spectrum test result diagram of quasi-suspended graphene according to an embodiment of the present invention;

[0022] Figure 5 The figure shows the transfer characteristic curve of a field effect transistor using quasi-suspended graphene as the channel material according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concept of the present invention.

[0024] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0025] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0026] When expressions such as "at least one of A, B, and C, etc." are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0027] Semiconductor technology is the cornerstone of modern electronic information science and technology and a key driver of global informatization. Silicon-based complementary metal oxide semiconductor (CMOS) and radio frequency circuits have achieved a certain level of complexity and integration, while also demonstrating excellent manufacturability and reliability. However, as semiconductor devices shrink in size, their development becomes increasingly challenging. Numerous physical effects that restrict their further development have begun to emerge, increasing device power consumption and causing issues such as overheating. This limits device response speed, impacts reliability, and reduces lifespan. As a result, the development of semiconductor devices is unable to keep pace with the rapid growth of information technology and industry. Therefore, the need to identify next-generation semiconductor functional materials is becoming increasingly urgent.

[0028] In recent years, two-dimensional materials, such as graphene, have garnered increasing attention due to their atomically thin structure and exceptional electrical properties. These materials are considered promising candidates for the continued miniaturization of transistors. As a leading two-dimensional material, graphene offers a promising alternative to silicon-based materials in the integrated circuit field due to its high carrier saturation velocity, high carrier mobility, and excellent thermal conductivity, as well as its compatibility with traditional semiconductor planar fabrication processes for device construction. The emergence of semiconducting graphene, in particular, has overcome key technical challenges that have long hindered the development of graphene electronics, paving a new path for the future of graphene.

[0029] Because semiconducting graphene exhibits semiconductor properties and quasi-suspended graphene exhibits semi-metallic properties, quasi-suspended graphene can be fabricated as an electrode and semiconducting graphene as a channel material. The two can then be seamlessly joined on a plane to form a continuous, overlapping whole. This approach maximizes the intrinsic properties of semiconducting graphene and allows the fabrication of high-performance quasi-suspended graphene-semiconducting graphene field-effect transistors and circuits. Therefore, the transformation of semiconducting graphene into quasi-suspended graphene is of great significance for graphene and even all-carbon devices and circuits.

[0030] Existing methods for preparing quasi-suspended graphene typically use hydrogen at temperatures above 860°C, such as 1200°C, to intercalate semiconducting graphene to form quasi-suspended graphene. However, hydrogen is inherently flammable and explosive. If a leak occurs in a hydrogen storage facility, accumulation of hydrogen to a certain concentration, and the presence of sparks or other triggering factors, could trigger an explosion, potentially harming personnel and equipment. Furthermore, the high temperature of 1200°C results in significant energy loss and increases production costs. Therefore, finding a safer and more cost-effective method for preparing quasi-suspended graphene could further promote the development of graphene electronics.

[0031] Figure 1 The flowchart of the method for preparing quasi-suspended graphene according to an embodiment of the present invention is schematically shown.

[0032] like Figure 1 As shown, the method includes operations S110 to S130.

[0033] In operation S110 , semiconductor graphene epitaxially grown on a silicon carbide substrate is placed in an annealing furnace, and air in the annealing furnace is extracted until the gas pressure in the annealing furnace drops to a first predetermined pressure range.

[0034] In operation S120, nitrogen or an inert gas is filled into the annealing furnace having a first predetermined pressure range until the pressure of the nitrogen or inert gas in the annealing furnace rises to a second predetermined pressure range.

[0035] In operation S130 , the semiconductor graphene is annealed in a nitrogen or inert gas atmosphere, and the semiconductor graphene is transformed into quasi-suspended graphene by adjusting at least one parameter of annealing temperature, annealing time, and gas flow rate.

[0036] According to the method for preparing quasi-suspended graphene provided by an embodiment of the present invention, quasi-suspended graphene can be obtained by annealing semiconductor graphene. During annealing, chemically stable gases such as nitrogen or inert gas can be used, and there is no need to use flammable and explosive hydrogen, which reduces the risk and improves the safety of preparing quasi-suspended graphene.

[0037] Optionally, the graphene epitaxially grown on the silicon carbide substrate can be placed in a rapid annealing furnace, the air in the rapid annealing furnace can be extracted, and the rapid annealing furnace can be evacuated to a vacuum state. The first predetermined pressure range can be used to detect whether the rapid annealing furnace has reached a vacuum state. The first predetermined pressure range can be adjusted according to actual needs. In one example, the first predetermined pressure range can be 10 -5 Pa ~10 -6 Pa, when the gas pressure in the rapid annealing furnace is 10 -5 Pa ~10 -6 Pa range, it can be indicated that the rapid annealing furnace has reached a vacuum state. In this case, the operation of extracting air from the rapid annealing furnace can be stopped.

[0038] In some embodiments, a vacuum pump and a molecular pump for assisting the vacuum pump may be used during the process of evacuating the rapid annealing furnace. -5 Pa ~10 -6In the case of Pa, the vacuum pump and the molecular pump can be turned off, but the molecular pump will not stop working immediately due to its own working characteristics. Therefore, in order to protect the stability of the molecular pump equipment, at the moment when the molecular pump completely stops working, nitrogen or at least one of the inert gases can be filled into the rapid annealing furnace that has been evacuated to vacuum. For example, only nitrogen, only one of the inert gases, nitrogen and at least one inert gas, or at least one inert gas can be introduced.

[0039] Optionally, the second predetermined pressure range can be used to detect whether the atmosphere concentration in the annealing furnace is suitable for annealing semiconductor graphene. The second predetermined pressure range can be adaptively adjusted according to actual needs. In one embodiment, the second predetermined pressure range can be 1Pa~10 3 Pa, for example, semiconductor graphene can be annealed when the pressure of nitrogen or inert gas reaches 3Pa, 5Pa, 10Pa, 15Pa, 20Pa, 50Pa, 100Pa, 200Pa, 500Pa and 1000Pa. The pressure of nitrogen or inert gas may affect the time required to transform semiconductor graphene into quasi-suspended graphene, as well as the crystal quality and other properties of the quasi-suspended graphene after transformation. For example, the greater the pressure of nitrogen or inert gas, the denser the concentration of nitrogen or inert gas atmosphere, the more embedded atoms such as N or Ar in the annealing furnace, and the more embedded atoms such as N or Ar may accelerate the saturation of silicon dangling bonds on the SiC surface, thereby shortening the time required to transform semiconductor graphene into quasi-suspended graphene. For example, the higher the concentration of the atmosphere in the annealing furnace, the more and more evenly the embedded atoms such as N or Ar are distributed around the semiconductor graphene. The evenly distributed embedded atoms such as N or Ar can evenly saturate the silicon dangling bonds on the SiC surface, thereby improving the crystal quality of the quasi-suspended graphene. However, it should be noted that an overly concentrated nitrogen or inert gas atmosphere (greater than 1000 Pa) may reduce the crystal quality and is not conducive to the transformation of semiconductor graphene into quasi-suspended graphene. Therefore, the pressure setting of the nitrogen or inert gas can be adaptively adjusted in combination with specific experimental conditions. In one example, the second predetermined pressure range can be preferably 1Pa ~ 10 2 Pa.

[0040] Optionally, when the gas pressure in the rapid annealing furnace reaches a second predetermined pressure range as detected by a pressure gauge, the semiconductor graphene can be annealed by adjusting at least one parameter among the annealing temperature, annealing time and gas flow rate to transform the semiconductor graphene into quasi-suspended graphene.

[0041] Optionally, the inert gas used in the above operation may include at least one of helium, neon, argon, krypton, xenon, and radon. By using nitrogen or an inert gas to prepare quasi-suspended graphene, the flammable and explosive hydrogen used in related art is replaced, thereby improving the safety of preparing quasi-suspended graphene.

[0042] Optionally, the annealing temperature in the above operation can be between 400°C and 850°C. Too low an annealing temperature (<400°C) may not be sufficient to convert the semiconducting graphene into quasi-suspended graphene, and too high an annealing temperature (>850°C) may destroy the structure and properties of the semiconducting graphene. Therefore, the annealing temperature is set between 400°C and 850°C. Preferably, the annealing temperature can be set between 500°C and 800°C.

[0043] The annealing temperature of the embodiment of the present invention can be between 400°C and 850°C, which is much lower than the 1200°C required for preparing quasi-suspended graphene using the hydrogen intercalation preparation method. The method of preparing quasi-suspended graphene of the present invention has low energy loss and low preparation cost.

[0044] Optionally, the annealing time in the above operation can be between 10 minutes and 60 minutes. An annealing time that is too short (<10 minutes) may not be sufficient to convert the semiconductor graphene into quasi-suspended graphene, and an annealing time that is too long (>60 minutes) may damage the structure and properties of the semiconductor graphene. Therefore, the annealing time is set between 10 minutes and 60 minutes. Preferably, the annealing time can be set between 15 minutes and 60 minutes.

[0045] Optionally, the gas flow rate in the above operation can be between 50 sccm and 500 sccm. A gas flow rate that is too small (<50 sccm) may not be sufficient to convert the semiconducting graphene into quasi-suspended graphene, and a gas flow rate that is too large (>500 sccm) may damage the structure and properties of the semiconducting graphene. Therefore, the gas flow rate is set between 50 sccm and 500 sccm. Preferably, the gas flow rate can be set between 100 sccm and 500 sccm.

[0046] Optionally, the annealing furnace may be equipped with an inlet valve for introducing nitrogen or an inert gas, and an exhaust valve for exhausting nitrogen or an inert gas.

[0047] Annealing the semiconductor graphene in a nitrogen or inert gas atmosphere includes: during the annealing process, both the inlet valve and the exhaust valve are in an open state, and the semiconductor graphene is annealed when the pressure of the nitrogen or inert gas introduced through the inlet valve rises to a second predetermined pressure range. For example, when annealing the semiconductor graphene in a nitrogen or inert gas atmosphere, the annealing can be performed while the nitrogen or inert gas is introduced when the pressure of the nitrogen or inert gas in the annealing furnace reaches the second predetermined pressure range.

[0048] Alternatively, when annealing the semiconductor graphene in a nitrogen or inert gas atmosphere, the semiconductor graphene can be annealed while the rapid annealing furnace is fully covered with the nitrogen or inert gas atmosphere, or while the concentration of the nitrogen or inert gas atmosphere is maintained within a second predetermined pressure range. For example, during the annealing of the semiconductor graphene, the tail valve is closed, and when the pressure of the nitrogen or inert gas introduced through the intake valve rises to the second predetermined pressure range, the intake valve is closed and the semiconductor graphene is annealed.

[0049] The present invention also provides quasi-suspended graphene prepared by the above-mentioned quasi-suspended graphene preparation method.

[0050] The present invention also provides a field effect transistor, in which quasi-suspended graphene is used as a channel material.

[0051] According to the method for preparing quasi-suspended graphene provided by an embodiment of the present invention, chemically stable nitrogen or inert gas is used instead of flammable and explosive hydrogen. As atoms such as N or Ar in the nitrogen or inert gas are embedded, the silicon dangling bonds on the SiC surface are saturated, and the semiconductor graphene can be completely separated from the substrate and transformed into independent graphene. This process does not require the use of hydrogen or high temperature (1200°C), thereby improving the safety of preparing quasi-suspended graphene and reducing costs.

[0052] The following further describes the preparation method of quasi-suspended graphene provided by the embodiments of the present invention through Examples 1 to 8.

[0053] Example 1

[0054] Epitaxially grown semiconductor graphene was used as the sample.

[0055] The sample was placed in a rapid annealing furnace with argon as the annealing gas. When the argon pressure reached 3 Pa, high-temperature annealing began. The annealing temperature was 650°C, the annealing time was 30 minutes, and the gas flow rate was 200 sccm. High-temperature annealing was performed on the semiconductor graphene.

[0056] Figure 2Ashows a structural diagram of semiconductor graphene under a scanning electron microscope according to an embodiment of the present invention; Figure 2B The structure of quasi-suspended graphene under a scanning electron microscope according to an embodiment of the present invention is shown.

[0057] like Figure 2A and Figure 2B As shown in the figure, after comparing the structural diagrams of semiconductor graphene and quasi-suspended graphene under a scanning electron microscope, it was found that the morphology of semiconductor graphene and quasi-suspended graphene under the electron microscope hardly changed, and both had good conductivity, indicating that high-temperature annealing (650°C) of semiconductor graphene in an argon atmosphere did not damage the surface of semiconductor graphene.

[0058] Figure 3A shows a graph showing Raman test results of semiconductor graphene according to an embodiment of the present invention; Figure 3B A graph showing the Raman test results of quasi-suspended graphene according to an embodiment of the present invention is shown.

[0059] like Figure 3A and Figure 3B As shown, the horizontal axis is Raman shift and the vertical axis is Raman intensity. After comparing the Raman test results of semiconductor graphene and quasi-suspended graphene, it is found that the Raman shift of the sample obtained by high-temperature annealing of semiconductor graphene in an argon atmosphere is 2700 cm -1 2D peaks representing the characteristic signals of graphene clearly appear on the left and right, proving that the quasi-suspended graphene obtained by annealing the semiconductor graphene has semi-metallic properties.

[0060] Figure 4A The result of quasi-suspended graphene under a scanning tunneling microscope according to an embodiment of the present invention is shown.

[0061] like Figure 4A As shown in , the suspended graphene is scanned with a scanning range of 8nm×8nm. Figure 4A As shown, the atomic structure of the quasi-suspended graphene obtained by annealing the semiconductor graphene presents the standard hexagonal structure of graphene.

[0062] Figure 4B A scanning tunneling spectrum test result diagram of quasi-suspended graphene according to an embodiment of the present invention is shown.

[0063] like Figure 4B In the figure shown, the horizontal axis is the bias voltage and the vertical axis is the differential conductance spectrum. Figure 4B Characterization: The quasi-suspended graphene exhibits the characteristics of zero band gap and is free of any doping, showing the characteristics of quasi-suspended graphene.

[0064] Figure 5The figure shows the transfer characteristic curve of a field effect transistor using quasi-suspended graphene as the channel material according to an embodiment of the present invention.

[0065] like Figure 5 As shown, the horizontal axis is the gate voltage and the vertical axis is the channel current. The quasi-suspended graphene is used as the channel material to prepare a field effect transistor, and the obtained field effect transistor is electrically tested. The transfer characteristic curve of the field effect transistor can be shown as follows Figure 5 As shown. Figure 5 From the curve shown, it can be seen that the transfer characteristic curve of the field effect transistor presents obvious graphene bipolar characteristics, which further proves that the semiconductor graphene becomes quasi-suspended graphene after annealing.

[0066] Example 2

[0067] Epitaxially grown semiconductor graphene was used as the sample.

[0068] The sample was placed in a rapid annealing furnace, using nitrogen as the annealing gas. High-temperature annealing began when the nitrogen pressure reached 15 Pa. The annealing temperature was 650°C, the annealing time was 30 minutes, and the gas flow rate was 200 sccm. The annealed semiconductor graphene was then subjected to relevant scanning electron microscopy, Raman spectroscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy.

[0069] Example 3

[0070] Epitaxially grown semiconductor graphene was used as the sample.

[0071] The sample was placed in a rapid annealing furnace, using argon as the annealing gas. High-temperature annealing began when the argon pressure reached 3 Pa. The annealing temperature was set at 400°C, the annealing time was 30 minutes, and the gas flow rate was 200 sccm. The annealed graphene was then subjected to relevant scanning electron microscopy, Raman spectroscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy.

[0072] Example 4

[0073] Epitaxially grown semiconductor graphene was used as the sample.

[0074] The sample was placed in a rapid annealing furnace, using argon as the annealing gas. High-temperature annealing began when the argon pressure reached 3 Pa. The annealing temperature was 850°C, the annealing time was 30 minutes, and the gas flow rate was 200 sccm. The annealed graphene was then subjected to relevant scanning electron microscopy, Raman spectroscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy.

[0075] Example 5

[0076] Epitaxially grown semiconductor graphene was used as the sample.

[0077] The sample was placed in a rapid annealing furnace, using argon as the annealing gas. High-temperature annealing began when the argon pressure reached 3 Pa. The annealing temperature was 650°C, the annealing time was 10 minutes, and the gas flow rate was 200 sccm. The annealed graphene was then subjected to relevant scanning electron microscopy, Raman spectroscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy.

[0078] Example 6

[0079] Epitaxially grown semiconductor graphene was used as the sample.

[0080] The sample was placed in a rapid annealing furnace, using argon as the annealing gas. High-temperature annealing began when the argon pressure reached 3 Pa. The annealing temperature was 650°C, the annealing time was 60 minutes, and the gas flow rate was 200 sccm. The annealed graphene was then subjected to relevant scanning electron microscopy, Raman spectroscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy.

[0081] Example 7

[0082] Epitaxially grown semiconductor graphene was used as the sample.

[0083] The sample was placed in a rapid annealing furnace, using argon as the annealing gas. High-temperature annealing began when the argon pressure reached 3 Pa. The annealing temperature was 650°C, the annealing time was 30 minutes, and the gas flow rate was 50 sccm. The annealed semiconductor graphene was then subjected to relevant scanning electron microscopy, Raman spectroscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy.

[0084] Example 8

[0085] Epitaxially grown semiconductor graphene was used as the sample.

[0086] The sample was placed in a rapid annealing furnace, using argon as the annealing gas. High-temperature annealing began when the argon pressure reached 3 Pa. The annealing temperature was 650°C, the annealing time was 30 minutes, and the gas flow rate was 500 sccm. The annealed graphene was then subjected to relevant scanning electron microscopy, Raman spectroscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy.

[0087] Comparative Example 1

[0088] Epitaxially grown semiconductor graphene was used as the sample.

[0089] The sample was placed in a rapid annealing furnace, using argon as the annealing gas. High-temperature annealing began when the argon pressure reached 3 Pa. The annealing temperature was 350°C, the annealing time was 30 minutes, and the gas flow rate was 200 sccm. The annealed graphene was then subjected to relevant scanning electron microscopy, Raman spectroscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy.

[0090] Comparative Example 2

[0091] Epitaxially grown semiconductor graphene was used as the sample.

[0092] The sample was placed in a rapid annealing furnace, using argon as the annealing gas. High-temperature annealing began when the argon pressure reached 3 Pa. The annealing temperature was 650°C, the annealing time was 8 minutes, and the gas flow rate was 200 sccm. The annealed graphene was then subjected to relevant scanning electron microscopy, Raman spectroscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy.

[0093] Comparative Example 3

[0094] Epitaxially grown semiconductor graphene was used as the sample.

[0095] The sample was placed in a rapid annealing furnace, using argon as the annealing gas. High-temperature annealing began when the argon pressure reached 3 Pa. The annealing temperature was 650°C, the annealing time was 30 minutes, and the gas flow rate was 40 sccm. The annealed graphene was then subjected to relevant scanning electron microscopy, Raman spectroscopy, scanning tunneling microscopy, and scanning tunneling spectroscopy.

[0096] By comparing Example 1 and Example 2, the effects of different gases on high-temperature annealing of semiconductor graphene can be obtained. The comparison results are shown in Table 1.

[0097] Table 1

[0098]

[0099] It can be seen from Table 1 above that high-temperature annealing of semiconductor graphene in both nitrogen atmosphere and argon atmosphere can transform semiconductor graphene into quasi-suspended graphene.

[0100] By comparing Example 1, Example 3, Example 4 and Comparative Example 1, the effects of different annealing temperatures on high-temperature annealed semiconductor graphene can be obtained. The comparison results are shown in Table 2.

[0101] Table 2

[0102]

[0103] As shown in Table 2 above, high-temperature annealing of semiconductor graphene at 400°C to 850°C can transform semiconductor graphene into quasi-suspended graphene. When the annealing temperature is lower than 400°C, semiconductor graphene will not undergo the transformation.

[0104] By comparing Example 1, Example 5, Example 6 and Comparative Example 2, the effects of different annealing times on high-temperature annealed semiconductor graphene can be obtained. The comparison results are shown in Table 3.

[0105] Table 3

[0106]

[0107] As shown in Table 3, high-temperature annealing of semiconductor graphene can transform semiconductor graphene into quasi-suspended graphene when the annealing time is between 10 minutes and 60 minutes. When the annealing time is less than 10 minutes, semiconductor graphene cannot be transformed.

[0108] By comparing Example 1, Example 7, Example 8 and Comparative Example 3, the effects of different gas flow rates on high-temperature annealing of semiconductor graphene can be obtained. The comparison results are shown in Table 4.

[0109] Table 4

[0110]

[0111] As shown in Table 4, high-temperature annealing of semiconducting graphene at a gas flow rate of 50 sccm to 500 sccm can transform semiconducting graphene into quasi-suspended graphene. When the gas flow rate is less than 50 sccm, semiconducting graphene cannot be transformed.

[0112] The method for preparing quasi-suspended graphene provided by the embodiment of the present invention does not require the use of flammable and explosive gases such as hydrogen, but instead uses gases with high chemical stability, which reduces the risk and provides an ideal solution for the formation of quasi-suspended graphene.

[0113] Compared to methods that use hydrogen intercalation to form quasi-suspended graphene from semiconducting graphene, the method for preparing quasi-suspended graphene in this embodiment of the present invention significantly reduces the temperature required, offering significant advantages in energy conservation and cost reduction. Field-effect transistor electronic devices fabricated using the quasi-suspended graphene formed in this embodiment of the present invention as the channel material exhibit excellent electrical performance, meeting the requirements of practical applications.

[0114] It should be noted that, unless it is clearly stated that there is a sequence of execution between different operations shown in the flowchart in the embodiments of the present invention, or there is a sequence of execution between different operations in technical implementation, otherwise, the execution order of multiple operations may not be prioritized, and multiple operations may also be executed simultaneously.

[0115] It will be understood by those skilled in the art that the features described in the various embodiments of the present invention may be combined and / or coupled in various ways, even if such combinations or couplings are not explicitly described in the present invention. In particular, the features described in the various embodiments of the present invention may be combined and / or coupled in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or couplings fall within the scope of the present invention.

[0116] The above describes embodiments of the present invention. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A method for preparing quasi-suspended graphene, characterized in that: The method comprises: The semiconductor graphene epitaxially grown on the silicon carbide substrate is placed in an annealing furnace, and the air in the annealing furnace is extracted until the gas pressure in the annealing furnace drops to a first predetermined pressure range, wherein the first predetermined pressure range includes 10 -5 Pa ~10 -6 Pa; Filling nitrogen or inert gas into the annealing furnace within a first predetermined pressure range until the pressure of the nitrogen or inert gas in the annealing furnace rises to a second predetermined pressure range, wherein the second predetermined pressure range includes 1Pa~10 3 Pa; The semiconductor graphene is annealed in the nitrogen or inert gas atmosphere, and the semiconductor graphene is converted into quasi-suspended graphene by adjusting at least one parameter among the annealing temperature, annealing time and gas flow rate, wherein the annealing temperature is between 400°C and 850°C, the annealing time is between 10 minutes and 60 minutes, and the gas flow rate is between 50 sccm and 500 sccm.

2. The preparation method according to claim 1, characterized in that The inert gas includes at least one of helium, neon, argon, krypton, xenon and radon.

3. The preparation method according to claim 1, characterized in that The annealing furnace is equipped with an inlet valve for introducing the nitrogen or inert gas, and an exhaust valve for exhausting the nitrogen or inert gas.

4. The preparation method according to claim 3, characterized in that The step of annealing the semiconductor graphene in the nitrogen or inert gas atmosphere comprises: During the annealing of the semiconductor graphene, the intake valve and the exhaust valve are both in an open state, and the semiconductor graphene is annealed when the pressure of the nitrogen or inert gas introduced through the intake valve rises to a second predetermined pressure range; or During the annealing process of the semiconductor graphene, the exhaust valve is in a closed state. When the pressure of the nitrogen or inert gas introduced through the intake valve rises to the second predetermined pressure range, the intake valve is closed and the semiconductor graphene is annealed.

5. A quasi-suspended graphene, characterized in that: The quasi-suspended graphene is prepared by the preparation method of any one of claims 1 to 4.

6. A field effect transistor, characterized in that: The quasi-suspended graphene as claimed in claim 5 is used as the channel material.

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