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

Abstract

The invention provides a preparation method of quasi-suspended graphene, quasi-suspended graphene and a field effect transistor, which can be applied to the technical field of graphene. The preparation method of the quasi-suspended graphene comprises the following steps: putting semiconductor graphene epitaxially grown on a silicon carbide substrate into an annealing furnace, and pumping out air in the annealing furnace until the gas pressure in the annealing furnace is reduced to a first preset pressure range; filling nitrogen or inert gas into the annealing furnace in a first preset pressure range until the pressure of the nitrogen or inert gas in the annealing furnace is increased to a second preset pressure range; the method comprises the following steps: annealing 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 annealing temperature, annealing duration and gas flow.

Description

Technical Field

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

[0002] The emergence of semiconductor graphene has promoted the development of graphene electronics and opened up a new path for the future of graphene. Semiconductor graphene can be transformed into quasi-suspended graphene. Currently, hydrogen is generally used to intercalate semiconductor graphene at a temperature above 860 °C (for example, 1200 °C) to form quasi-suspended graphene. However, hydrogen itself has the properties of flammability and explosiveness. Once there is a leakage in the place where hydrogen is stored, and hydrogen accumulates to a certain concentration with an inducement such as a spark, an explosion may occur, causing harm to personnel and equipment, and having low safety. Summary of the Invention

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

[0004] One aspect of the present application provides a preparation method of quasi-suspended graphene, including: putting the semiconductor graphene epitaxially grown on a silicon carbide substrate into an annealing furnace, and pumping out the air in the annealing furnace until the gas pressure in the annealing furnace drops to a first predetermined pressure range; filling the annealing furnace with nitrogen or an inert gas 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 atmosphere of the nitrogen or inert gas, and converting the semiconductor graphene into quasi-suspended graphene by adjusting at least one parameter among the annealing temperature, annealing duration 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 duration 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 to 10 -6 Pa; the second predetermined pressure range includes 1 Pa to 10 3 Pa.

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

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

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

[0013] Another aspect of the present invention also provides a field effect transistor, which uses 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. When annealing, a chemically stable gas (nitrogen or inert gas) is used. 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 can avoid using flammable and explosive hydrogen, reducing the danger and improving the safety of preparing quasi-suspended graphene. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematically shows a flowchart of a method for preparing quasi-suspended graphene according to an embodiment of the present invention;

[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 Raman test result diagram 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 the result diagram of quasi-suspended graphene according to an embodiment of the present invention under a scanning tunneling microscope;

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

[0022] Figure 5 Shows the transfer characteristic curve of a field effect transistor with quasi-suspended graphene as the channel material according to an embodiment of the present invention. Detailed implementation manners

[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 merely exemplary and are not intended to limit the scope of the present invention. In the following detailed description, for the sake of explanation, many specific details are set forth in order to provide a comprehensive understanding of the embodiments of the present invention. However, obviously, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present invention.

[0024] The terms used herein are merely for describing specific embodiments and are not intended to limit the present invention. The terms "including", "comprising", etc. used herein indicate the presence of the described 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] In the case of using expressions such as "at least one of A, B, and C, etc.", generally, it should be interpreted according to the meaning that those skilled in the art usually understand this expression (for example, "a system having at least one of A, B, and C" should include, but is not limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0027] Semiconductor technology is the cornerstone of the development of modern electronic information science and technology and a key driving force for promoting global informatization. Complementary Metal Oxide Semiconductor (CMOS) and radio frequency circuits based on silicon have reached a certain level of complexity and integration, and at the same time have shown excellent manufacturability and reliability. However, as the size of semiconductor devices becomes smaller and smaller, the development of semiconductor devices has become increasingly challenging. Many physical effects that limit the further development of semiconductor devices have emerged, resulting in an increase in the power consumption of the devices and causing problems such as device heating, limiting the response speed of the devices, affecting the reliability and lifespan of the devices, etc. The development of semiconductor devices can no longer meet the rapid development of information technology and industry. Therefore, the need to find the next-generation semiconductor functional materials is becoming increasingly urgent.

[0028] In recent years, two-dimensional materials represented by graphene have attracted increasing attention due to their atomic-level thickness and excellent electrical properties. Two-dimensional materials represented by graphene are considered to be promising materials for promoting the continuous miniaturization of transistor sizes. As a typical two-dimensional material, graphene has a high carrier saturation velocity, a high carrier mobility, and excellent thermal conductivity, and is compatible with traditional semiconductor planar fabrication processes when constructing devices. Therefore, it is expected to become a substitute for silicon-based materials in the field of integrated circuits. In particular, the emergence of semiconductor graphene has overcome the key technical problems that have long hindered the development of graphene electronics and opened up a new path for the future of graphene.

[0029] Based on the properties that semiconductor graphene exhibits semiconductor characteristics and quasi-suspended graphene exhibits semi-metal characteristics, quasi-suspended graphene can be fabricated into the electrode part, and semiconductor graphene can be fabricated into the channel material, and a seamless and continuous whole of quasi-suspended graphene and semiconductor graphene can be formed on the plane. In this way, the intrinsic properties of semiconductor graphene can be utilized to the greatest extent, and excellent-performance quasi-suspended graphene-semiconductor graphene field-effect transistors and circuits can be fabricated using this structure. Based on this, the transformation of semiconductor 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 generally use hydrogen at temperatures above 860 °C, such as 1200 °C, to intercalate semiconductor graphene to form quasi-suspended graphene. However, hydrogen itself is flammable and explosive. Once there is a leak in the place where hydrogen is stored, when hydrogen accumulates to a certain concentration and there are incentives such as sparks, an explosion may be triggered, causing harm to personnel and equipment. Moreover, the high temperature of 1200 °C results in large energy losses and further increases the preparation cost. Therefore, finding a safer and lower-cost method for preparing quasi-suspended graphene can further promote the development of graphene electronics.

[0031] Figure 1 Schematically shows a flowchart of a method for preparing quasi-suspended graphene according to an embodiment of the present invention.

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

[0033] In operation S110, the semiconductor graphene epitaxially grown on a silicon carbide substrate is placed in an annealing furnace, and the air in the annealing furnace is pumped out 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 nitrogen or the inert gas in the annealing furnace rises to a second predetermined pressure range.

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

[0036] According to the method for preparing quasi-suspended graphene provided by the embodiment of the present invention, quasi-suspended graphene can be obtained by annealing semiconductor graphene. When annealing, chemically stable gases such as nitrogen or inert gases can be used, without using flammable and explosive hydrogen, reducing the danger and improving 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, and the air in the rapid annealing furnace is pumped out to make the rapid annealing furnace in a vacuum state. The first predetermined pressure range can be used to detect whether the inside of the rapid annealing furnace reaches 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 within the range of 10 -5 Pa ~ 10 -6 Pa, it can be characterized that the inside of the rapid annealing furnace reaches a vacuum state. In this case, the operation of pumping out air from the rapid annealing furnace can be stopped.

[0038] In some embodiments, during the process of evacuating the rapid annealing furnace, a vacuum pump and a molecular pump for assisting the vacuum pump can be used. When it is detected by a pressure gauge that the gas pressure inside the rapid annealing furnace reaches 10 -5 Pa ~ 10 -6In the case of [[Pa]], the vacuum pump and the molecular pump can be turned off. However, due to its own working characteristics, the molecular pump will not stop working immediately. Therefore, to protect the stability of the molecular pump equipment, at the moment when the molecular pump completely stops working, at least one of nitrogen or inert gas can be filled into the rapidly annealed furnace that has been evacuated to vacuum. For example, only nitrogen is introduced, only one of the inert gases is introduced, nitrogen and at least one inert gas are introduced, or at least one inert gas is introduced, etc.

[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 adjusted adaptively according to actual needs. In one embodiment, the second predetermined pressure range can be 1 Pa to 10 3 Pa. For example, semiconductor graphene can be annealed when the pressure of nitrogen or inert gas reaches 3 Pa, 5 Pa, 10 Pa, 15 Pa, 20 Pa, 50 Pa, 100 Pa, 200 Pa, 500 Pa, and 1000 Pa, etc. 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 transformed quasi-suspended graphene. For example, the greater the pressure of nitrogen or inert gas, the higher the concentration of nitrogen or inert gas atmosphere, and the more embedded atoms such as N or Ar in the annealing furnace. The excessive N or Ar and other embedded atoms 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. Another example is that the higher the atmosphere concentration in the annealing furnace, the more and more uniform the distribution of embedded atoms such as N or Ar around the semiconductor graphene. The uniformly distributed N or Ar and other embedded atoms can make the silicon dangling bonds on the SiC surface saturated uniformly, 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 setting of the pressure of nitrogen or inert gas can be adjusted adaptively in combination with specific experimental conditions. In one example, the second predetermined pressure range can be preferably 1 Pa to 10 2 Pa.

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

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

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

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

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

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

[0046] Optionally, the annealing furnace may be configured with an intake valve for introducing nitrogen or inert gas and an exhaust valve for discharging nitrogen or inert gas.

[0047] Annealing the semiconductor graphene in a nitrogen or inert gas atmosphere includes: during the annealing of the semiconductor graphene, both the intake valve and the exhaust valve are in an open state, and when the pressure of the nitrogen or inert gas introduced through the intake valve rises to the second predetermined pressure range, the semiconductor graphene is annealed. For example, when annealing the semiconductor graphene in a nitrogen or inert gas atmosphere, annealing can be carried out while introducing nitrogen or inert gas 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, annealing can be carried out when the rapid annealing furnace is filled with a nitrogen or inert gas atmosphere, or when the atmosphere concentration of the nitrogen or inert gas is maintained within the second predetermined pressure range. For example, during the annealing of the semiconductor graphene, the exhaust valve is in a closed state, 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 a quasi-suspended graphene prepared by the above method for preparing quasi-suspended graphene.

[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 the embodiments of the present invention, chemically stable nitrogen or inert gas is used to replace flammable and explosive hydrogen. With the embedding atoms such as N or Ar in the nitrogen or inert gas, 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 and does not require high temperature (1200 °C), improving the safety of preparing quasi-suspended graphene and reducing the cost at the same time.

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

[0053] Example 1

[0054] Use epitaxially grown semiconductor graphene as a sample.

[0055] Place the sample in a rapid annealing furnace. The annealing gas is argon. When the argon reaches a pressure of 3 Pa, high-temperature annealing is started. The annealing temperature is 650 °C, the annealing time is 30 min, and the gas flow rate is 200 sccm. High-temperature annealing is carried out on the semiconductor graphene.

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

[0057] As Figure 2A and Figure 2B shown, by comparing the structural diagrams of semiconductor graphene and quasi-suspended graphene under a scanning electron microscope, it is found that the morphologies of semiconductor graphene and quasi-suspended graphene hardly change under the electron microscope, and both have good conductivity, indicating that high-temperature annealing (650 °C) of semiconductor graphene in an argon atmosphere does not damage the surface of semiconductor graphene.

[0058] Figure 3A Shows the Raman test result diagram of semiconductor graphene according to an embodiment of the present invention; Figure 3B Shows the Raman test result diagram of quasi-suspended graphene according to an embodiment of the present invention.

[0059] As Figure 3A and Figure 3B shown, the abscissa is the Raman shift and the ordinate is the Raman intensity. By comparing the Raman test result diagrams of semiconductor graphene and quasi-suspended graphene, it is found that for high-temperature annealing of semiconductor graphene in an argon atmosphere, the Raman shift of the obtained sample significantly shows a 2D peak representing the characteristic signal of graphene at about 2700 cm -1 proving that the quasi-suspended graphene obtained by annealing semiconductor graphene already has semi-metallic properties.

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

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

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

[0063] As Figure 4B shown in the figure, the abscissa is the bias voltage and the ordinate is the differential conductance spectrum, Figure 4B characterizing that the quasi-suspended graphene presents the characteristics of a zero bandgap and has no doping, showing the characteristics of quasi-suspended graphene.

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

[0065] As Figure 5 shown, the abscissa is the gate voltage and the ordinate is the channel current. Quasi-suspended graphene is used as the channel material to fabricate a field-effect transistor, and the obtained field-effect transistor is electrically tested. The transfer characteristic curve of the field-effect transistor can be as Figure 5 shown. According to Figure 5 the curve shown, it can be obtained that the transfer characteristic curve of the field-effect transistor exhibits obvious bipolar characteristics of graphene, further proving that semiconductor graphene becomes quasi-suspended graphene after annealing.

[0066] Example 2

[0067] Use epitaxially grown semiconductor graphene as the sample.

[0068] Put the sample into a rapid annealing furnace. The annealing gas is nitrogen. When the nitrogen reaches a pressure of 15 Pa, high-temperature annealing is started. The annealing temperature is 650 °C, the annealing time is 30 min, and the gas flow rate is 200 sccm. High-temperature annealing is performed on the semiconductor graphene. Perform relevant scanning electron microscopy tests, Raman tests, scanning tunneling microscopy tests, and scanning tunneling spectroscopy tests on the annealed semiconductor graphene.

[0069] Example 3

[0070] Use epitaxially grown semiconductor graphene as the sample.

[0071] Put the sample into a rapid annealing furnace. The annealing gas is argon. When the argon reaches a pressure of 3 Pa, high-temperature annealing is started. The annealing temperature is 400 °C, the annealing time is 30 min, and the gas flow rate is 200 sccm. High-temperature annealing is performed on the semiconductor graphene. Perform relevant scanning electron microscopy tests, Raman tests, scanning tunneling microscopy tests, and scanning tunneling spectroscopy tests on the annealed semiconductor graphene.

[0072] Example 4

[0073] Use epitaxially grown semiconductor graphene as the sample.

[0074] Put the sample into a rapid annealing furnace. The annealing gas is argon. When the argon reaches a pressure of 3 Pa, high-temperature annealing is started. The annealing temperature is 850 °C, the annealing time is 30 min, and the gas flow rate is 200 sccm. High-temperature annealing is performed on the semiconductor graphene. Perform relevant scanning electron microscopy tests, Raman tests, scanning tunneling microscopy tests, and scanning tunneling spectroscopy tests on the annealed semiconductor graphene.

[0075] Example 5

[0076] Use epitaxially grown semiconductor graphene as the sample.

[0077] Place the sample in a rapid annealing furnace. The annealing gas is argon. When the argon pressure reaches 3 Pa, start high-temperature annealing. The annealing temperature is 650 °C, the annealing time is 10 min, and the gas flow rate is 200 sccm. Perform high-temperature annealing on the semiconductor graphene. Conduct relevant scanning electron microscopy tests, Raman tests, scanning tunneling microscopy tests, and scanning tunneling spectroscopy tests on the annealed semiconductor graphene.

[0078] Example 6

[0079] Use epitaxially grown semiconductor graphene as the sample.

[0080] Place the sample in a rapid annealing furnace. The annealing gas is argon. When the argon pressure reaches 3 Pa, start high-temperature annealing. The annealing temperature is 650 °C, the annealing time is 60 min, and the gas flow rate is 200 sccm. Perform high-temperature annealing on the semiconductor graphene. Conduct relevant scanning electron microscopy tests, Raman tests, scanning tunneling microscopy tests, and scanning tunneling spectroscopy tests on the annealed semiconductor graphene.

[0081] Example 7

[0082] Use epitaxially grown semiconductor graphene as the sample.

[0083] Place the sample in a rapid annealing furnace. The annealing gas is argon. When the argon pressure reaches 3 Pa, start high-temperature annealing. The annealing temperature is 650 °C, the annealing time is 30 min, and the gas flow rate is 50 sccm. Perform high-temperature annealing on the semiconductor graphene. Conduct relevant scanning electron microscopy tests, Raman tests, scanning tunneling microscopy tests, and scanning tunneling spectroscopy tests on the annealed semiconductor graphene.

[0084] Example 8

[0085] Use epitaxially grown semiconductor graphene as the sample.

[0086] Place the sample in a rapid annealing furnace. The annealing gas is argon. When the argon pressure reaches 3 Pa, start high-temperature annealing. The annealing temperature is 650 °C, the annealing time is 30 min, and the gas flow rate is 500 sccm. Perform high-temperature annealing on the semiconductor graphene. Conduct relevant scanning electron microscopy tests, Raman tests, scanning tunneling microscopy tests, and scanning tunneling spectroscopy tests on the annealed semiconductor graphene.

[0087] Comparative Example 1

[0088] Use epitaxially grown semiconductor graphene as the sample.

[0089] Put the sample into a rapid annealing furnace. The annealing gas is argon. When the argon pressure reaches 3 Pa, start high-temperature annealing. The annealing temperature is 350 °C, the annealing time is 30 min, and the gas flow rate is 200 sccm. Conduct high-temperature annealing on the semiconductor graphene. Conduct relevant scanning electron microscopy tests, Raman tests, scanning tunneling microscopy tests, and scanning tunneling spectroscopy tests on the annealed semiconductor graphene.

[0090] Comparative Example 2

[0091] Use epitaxially grown semiconductor graphene as the sample.

[0092] Put the sample into a rapid annealing furnace. The annealing gas is argon. When the argon pressure reaches 3 Pa, start high-temperature annealing. The annealing temperature is 650 °C, the annealing time is 8 min, and the gas flow rate is 200 sccm. Conduct high-temperature annealing on the semiconductor graphene. Conduct relevant scanning electron microscopy tests, Raman tests, scanning tunneling microscopy tests, and scanning tunneling spectroscopy tests on the annealed semiconductor graphene.

[0093] Comparative Example 3

[0094] Use epitaxially grown semiconductor graphene as the sample.

[0095] Put the sample into a rapid annealing furnace. The annealing gas is argon. When the argon pressure reaches 3 Pa, start high-temperature annealing. The annealing temperature is 650 °C, the annealing time is 30 min, and the gas flow rate is 40 sccm. Conduct high-temperature annealing on the semiconductor graphene. Conduct relevant scanning electron microscopy tests, Raman tests, scanning tunneling microscopy tests, and scanning tunneling spectroscopy tests on the annealed semiconductor graphene.

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

[0097] Table 1

[0098]

[0099] As can be seen from Table 1 above, high-temperature annealing of semiconductor graphene in a nitrogen atmosphere and an argon atmosphere can both transform the 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 the high-temperature annealing of semiconductor graphene can be obtained, and the comparison results are shown in Table 2.

[0101] Table 2

[0102]

[0103] As can be seen from Table 2 above, high-temperature annealing of semiconductor graphene at an annealing temperature of 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 transform.

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

[0105] Table 3

[0106]

[0107] As can be seen from Table 3 above, high-temperature annealing of semiconductor graphene with an annealing duration of 10 min to 60 min can transform semiconductor graphene into quasi-suspended graphene. When the annealing duration is less than 10 min, semiconductor graphene cannot transform.

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

[0109] Table 4

[0110]

[0111] As can be seen from Table 4 above, high-temperature annealing of semiconductor graphene with a gas flow rate of 50 sccm to 500 sccm can transform semiconductor graphene into quasi-suspended graphene. When the gas flow rate is less than 50 sccm, semiconductor graphene cannot transform.

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

[0113] Compared with the method of forming quasi-suspended graphene by hydrogen intercalation of semiconductor graphene, the temperature of the method for preparing quasi-suspended graphene in the embodiments of the present invention is greatly reduced, and it has obvious advantages in energy conservation and cost reduction. The field-effect transistor electronic device prepared by using the quasi-suspended graphene formed in the embodiments of the present invention as a channel material has excellent electrical properties and meets the requirements of practical applications.

[0114] It should be noted that, unless it is explicitly stated that there is a sequential execution order between different operations shown in the flowcharts in the embodiments of the present invention, or there is a sequential execution order in the technical implementation of different operations, the execution order between multiple operations can be unsequenced, and multiple operations can also be executed simultaneously.

[0115] Those skilled in the art can understand that the features described in the various embodiments of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present invention.

[0116] The embodiments of the present invention have been described above. However, these embodiments are only for illustrative purposes and not for limiting the scope of the present invention. Although the embodiments have been described separately above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should fall within the scope of the present invention.

Claims

1. A preparation method of quasi-suspended graphene, characterized in that, The method includes: Put the semiconductor graphene epitaxially grown on a silicon carbide substrate into an annealing furnace, and evacuate the air in the annealing furnace until the gas pressure in the annealing furnace drops to a first predetermined pressure range; Fill the annealing furnace with nitrogen or an inert gas 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; Anneal the semiconductor graphene in the atmosphere of the nitrogen or inert gas, and transform the semiconductor graphene into quasi-suspended graphene by adjusting at least one parameter among the annealing temperature, annealing duration, and gas flow rate.

2. The preparation method according to claim 1, wherein 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 temperature is between 400°C and 850°C.

4. The preparation method according to claim 1, characterized in that, The annealing duration is between 10 minutes and 60 minutes.

5. The preparation method according to claim 1, wherein, The gas flow rate is between 50 sccm and 500 sccm.

6. The preparation method according to claim 1, characterized in that, The first predetermined pressure range includes 10 -5 Pa to 10 -6 Pa; the second predetermined pressure range includes 1 Pa to 10 3 Pa.

7. The preparation method according to claim 1, characterized in that, The annealing furnace is configured with an intake valve for introducing the nitrogen or inert gas and an exhaust valve for discharging the nitrogen or inert gas.

8. The preparation method according to claim 7, characterized in that, The annealing of the semiconductor graphene in the atmosphere of the nitrogen or inert gas includes: During the annealing of the semiconductor graphene, both the intake valve and the exhaust valve are in an open state, and when the pressure of the nitrogen or inert gas introduced through the intake valve rises to the second predetermined pressure range, anneal the semiconductor graphene; or During the annealing of the semiconductor graphene, the exhaust valve is in a closed state, and when the pressure of the nitrogen or inert gas introduced through the intake valve rises to the second predetermined pressure range, close the intake valve and anneal the semiconductor graphene.

9. A quasi-suspended graphene, characterized in that, Prepared by using the preparation method of quasi-suspended graphene according to any one of claims 1 to 8.

10. A field effect transistor, characterized in that, Use the quasi-suspended graphene according to claim 9 as a channel material.

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