Field effect transistor and method of manufacturing the same

Abstract

A method for manufacturing a field effect transistor includes the steps of: providing a graphene nanoribbon composite structure including a substrate and a plurality of graphene nanoribbons, the plurality of graphene nanoribbons being spaced apart on the substrate and extending in the same direction, the substrate having a plurality of spaced-apart protrusions; forming a source electrode and a drain electrode at both ends of each graphene nanoribbon in a spaced-apart manner and electrically connecting the source electrode and the drain electrode to the graphene nanoribbon; forming an insulating layer on a surface of the plurality of graphene nanoribbons away from the substrate; and forming a gate electrode on a surface of the insulating layer away from the substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to a field effect transistor and a preparation method thereof. BACKGROUND

[0002] Field Effect Transistor (FET) is also called field effect tube, which mainly has two types: junction FET (JFET) and metal-oxide semiconductor FET (MOS-FET). Field effect transistor is a voltage-controlled semiconductor device with majority carriers participating in conduction, also known as unipolar transistor. Field effect transistor has high input resistance, small noise and low power, and has become a strong competitor of bipolar transistor and power transistor.

[0003] In the prior art, the material forming the semiconductor layer in the field effect transistor is amorphous silicon or polycrystalline silicon. The preparation technology of amorphous silicon field effect transistor using amorphous silicon as the semiconductor layer is relatively mature, but in the amorphous silicon field effect transistor, the semiconductor layer usually contains a large number of dangling bonds, which makes the mobility of the carriers very low, thereby resulting in a slow response speed of the field effect transistor. The field effect transistor using polycrystalline silicon as the semiconductor layer has a higher carrier mobility than the field effect transistor using amorphous silicon as the semiconductor layer, and thus has a faster response speed. However, the low-temperature preparation of polycrystalline silicon field effect transistor has a high cost and a complex method, and it is difficult to prepare in a large area. SUMMARY

[0004] Therefore, it is necessary to provide a field effect transistor and a preparation method thereof, wherein the semiconductor layer is a plurality of graphene nanoribbons arranged in order, which can be prepared in a large area with low cost and energy consumption

[0005] A preparation method of a field effect transistor, comprising the following steps:

[0006] Providing a graphene nanoribbon composite structure, the graphene nanoribbon composite structure comprising a substrate and a plurality of graphene nanoribbons, the plurality of graphene nanoribbons being arranged at intervals on the substrate and extending in the same direction, the substrate having a plurality of protrusions arranged at intervals;

[0007] Forming a source electrode and a drain electrode at intervals at both ends of each graphene nanoribbon, and electrically connecting the source electrode and the drain electrode with the graphene nanoribbon;

[0008] Forming an insulating layer on the surface of the plurality of graphene nanoribbons away from the substrate; and

[0009] Forming a gate electrode on the surface of the insulating layer away from the substrate.

[0010] A field effect transistor comprises a semiconductor layer, a source, a drain, an insulating layer and a gate, the semiconductor layer is a graphene nanoribbon composite structure, the graphene nanoribbon composite structure comprises a substrate and a plurality of graphene nanoribbons, the substrate comprises a substrate body and a plurality of protrusions, the plurality of protrusions are arranged on the surface of the substrate body, and the plurality of graphene nanoribbons are arranged on the substrate body and extend in the same direction.

[0011] A field effect transistor comprises a semiconductor layer, a source and a drain, the semiconductor layer is a graphene nanoribbon composite structure, the graphene nanoribbon composite structure comprises a substrate and a plurality of graphene nanoribbons, the substrate comprises a substrate body and a plurality of protrusions, the plurality of protrusions are arranged on the surface of the substrate body, and the plurality of graphene nanoribbons are arranged on the substrate body and extend in the same direction; the substrate is a silicon wafer with silicon oxide, and the plurality of graphene nanoribbons are arranged on the silicon oxide.

[0012] Compared with the prior art, in the field effect transistor provided by the application, the semiconductor layer is a plurality of graphene nanoribbons arranged in order, the plurality of graphene nanoribbons are obtained by combining a graphene film with a substrate with a plurality of protrusions, before the combination, water or an organic solvent is arranged on the substrate to form wrinkles near the protrusions, and the graphene film is further etched. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The process flow chart of the preparation method of the graphene nanoribbon composite structure provided by the first embodiment of the application is shown.

[0014] Figure 2 The atomic force microscope (AFM) photo of the second composite structure provided by the first embodiment of the application is shown.

[0015] Figure 3 The scanning electron microscope (SEM) photo of the graphene nanoribbon composite structure is shown. Figure 1 The scanning electron microscope (SEM) photo of the graphene nanoribbon composite structure is shown.

[0016] Figure 4 The atomic force microscope (AFM) photo of the graphene nanoribbon composite structure is shown. Figure 1 The atomic force microscope (AFM) photo of the graphene nanoribbon composite structure is shown.

[0017] Figure 5 The top view structural schematic diagram of the graphene nanoribbon composite structure is shown. Figure 1 The top view structural schematic diagram of the graphene nanoribbon composite structure is shown.

[0018] Figure 6 The process flow chart of the preparation method of the graphene nanoribbon composite structure provided by the second embodiment of the application is shown.

[0019] Figure 7 A process flow chart of the preparation method of the graphene nanoribbon composite structure provided by the third embodiment of the present application is shown in FIG. 3.

[0020] Figure 8 A process flow chart of the preparation method of the graphene nanoribbon composite structure provided by the fourth embodiment of the present application is shown in FIG. 4.

[0021] Figure 9 A process flow chart of the preparation method of the field effect transistor provided by the fifth embodiment of the present application is shown in FIG. 5.

[0022] Figure 10 A structure diagram of the source electrode, the drain electrode and the graphene nanoribbon electrically connected provided by the fifth embodiment of the present application is shown in FIG. 6.

[0023] Figure 11 A structure diagram of the field effect transistor provided by the fifth embodiment of the present application is shown in FIG. 7.

[0024] Figure 12 A process flow chart of the preparation method of the field effect transistor provided by the sixth embodiment of the present application is shown in FIG. 8.

[0025] Figure 13 A structure diagram of the field effect transistor provided by the sixth embodiment of the present application is shown in FIG. 9.

[0026] Figure 14 A process flow chart of the preparation method of the field effect transistor provided by the seventh embodiment of the present application is shown in FIG. 10.

[0027] Figure 15 A structure diagram of the interdigital electrode provided by the seventh embodiment of the present application is shown in FIG. 11.

[0028] Figure 16 A top view structure diagram of the field effect transistor provided by the seventh embodiment of the present application is shown in FIG. 12.

[0029] Main element symbol explanation

[0030] Graphene nanoribbon composite structure 20

[0031] Substrate 10

[0032] Mask layer 12

[0033] First surface 122

[0034] Second surface 124

[0035] Through hole 126

[0036] Metal layer 14

[0037] Substrate 16

[0038] Substrate body 162

[0039] protrusion 164

[0040] growth substrate 11

[0041] graphene film 13

[0042] adhesive layer 15

[0043] first composite structure 17

[0044] second composite structure 19

[0045] folds 18

[0046] graphene nanoribbons 22

[0047] field effect transistor 100, 200, 300

[0048] source 102

[0049] drain 104

[0050] insulating layer 106

[0051] gate 108

[0052] interdigital electrode 210

[0053] first electrode 212

[0054] first sub-electrode 2120

[0055] connection portion 2122

[0056] second electrode 214

[0057] second sub-electrode 2140

[0058] The following specific embodiments will further illustrate the present application in conjunction with the above figures. DETAILED DESCRIPTION

[0059] The field effect transistor and the preparation method thereof provided by the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0060] Please refer to Figure 1 , Figure 2 and Figure 5 , the first embodiment of the present application provides a preparation method of a graphene nanoribbon composite structure 20, comprising the following steps:

[0061] S11, a mask layer 12 is arranged on a substrate 10, the mask layer 12 has opposite first and second surfaces 122 and 124, the first surface 122 is in direct contact with the substrate 10, the mask layer 12 has a plurality of spaced-apart through holes 126 extending from the first surface 122 to the second surface 124, an X direction and a Y direction are defined on the surface of the substrate 10, the X direction and the Y direction are perpendicular to each other;

[0062] S12, a metal layer 14 is arranged on the second surface 124, and the metal layer 14 fills the through holes 126;

[0063] S13, the mask layer 12 is peeled off, the metal layer 14 on the second surface 124 of the mask layer 12 is also removed, and the metal layer 14 in the through holes 126 remains on the substrate 10;

[0064] S14, the metal layer 14 remaining on the substrate 10 is used as a mask to etch the substrate 10;

[0065] S15, the metal layer 14 remaining on the substrate 10 is removed, and a substrate 16 is obtained, the substrate 16 includes a substrate body 162 and a plurality of spaced-apart protrusions 164 arranged on the surface of the substrate body 162;

[0066] S16, a graphene film 13 is grown on a growth substrate 11;

[0067] S17, an adhesive layer 15 is arranged on the surface of the graphene film 13 away from the growth substrate 11, the growth substrate 11 is removed, and water or an organic solvent is used for cleaning;

[0068] S18, the graphene film 13 and the adhesive layer 15 are taken out of the water or the organic solution by using the substrate 16, and dried to obtain a first composite structure 17, the first composite structure 17 includes the substrate 16, the graphene film 13 and the adhesive layer 15, the graphene film 13 is located between the adhesive layer 15 and the substrate 16, and the graphene film 13 is in direct contact with the protrusions 164;

[0069] S19, the adhesive layer 15 is removed to obtain a second composite structure 19, the second composite structure 19 includes the substrate 16 and the graphene film 13, the graphene film 13 is located on the surface of the protrusions 164 and the surface of the substrate body 162 between adjacent protrusions 164, and the graphene film 13 forms a wrinkle 18 near the protrusions 164, the wrinkle 18 is located on the surface of the substrate body 162 between adjacent protrusions 164 and extends in the Y direction, and the thickness of the graphene film 13 at the wrinkle 18 is greater than the thickness of the graphene film 13 on the surface of the substrate body 162 between adjacent protrusions 164;

[0070] S20, etching away from the surface of the substrate 16 of the graphene film 13, removing the graphene film 13 on the protrusions 164 and the graphene film 13 on the surface of the substrate body 162 between the adjacent protrusions 164 except the wrinkle 18, so as to obtain a graphene nanoribbon composite structure 20, which comprises the substrate body 162, the plurality of protrusions 164 and a plurality of mutually parallel graphene nanoribbons 22, the plurality of graphene nanoribbons 22 are arranged on the substrate body 162.

[0071] In step S11, the material of the substrate 10 can be a conductor, a semiconductor or an insulating material. Specifically, the material of the substrate 10 can be gallium nitride, gallium arsenide, sapphire, aluminum oxide, magnesium oxide, silicon, silicon dioxide, silicon nitride, quartz or glass, etc. The material of the substrate 10 can also be a flexible material such as polyethylene terephthalate (PET), polyimide (PI), etc. Further, the material of the substrate 10 can also be a doped semiconductor material such as P-type gallium nitride, N-type gallium nitride, etc. The size, thickness and shape of the substrate 10 are not limited and can be selected according to actual needs. Preferably, the material of the substrate 10 is silicon oxide. In this embodiment, the substrate 10 is a silicon wafer with a thickness of 300 nm (nanometer) of silicon oxide.

[0072] The material of the mask layer 12 is not limited and can be ZEP520A, HSQ (hydrogen silsesquioxane), PMMA (Polymethylmethacrylate), PS (Polystyrene), SOG (Silicon on glass), MMA (Methylmethacrylate) or other organic silicon-based oligomers, etc. The mask layer 12 can be formed by deposition on the surface of the substrate 10 and then dried, or can be formed by a screen printing method. In this embodiment, the material of the mask layer 12 is PMMA.

[0073] The way of arranging a plurality of through holes 126 on the mask layer 12 is not limited. In this embodiment, an array of through holes 126 with a diameter of 40 nm, a distance between through holes 126 in each column of 500 nm or less and a distance between columns of 500 nm or more is exposed by electron beam exposure. That is, in the X direction, the distance between adjacent through holes 126 is greater than 500 nm; in the Y direction, the distance between adjacent through holes 126 is less than 500 nm. The shape of the through holes 126 is not limited and can be circular, square, triangular, etc.

[0074] In step S12, the metal layer 14 can be deposited on the second surface 124 of the mask layer 12 by electron beam evaporation, ion beam sputtering or other methods, and fill the through holes 126. The material of the metal layer 14 is a metal that can be removed by etching solution, such as iron, gold, chromium, copper or aluminum, etc. The thickness of the metal layer 14 is not limited. In this embodiment, the metal layer 14 is a copper layer with a thickness of 15 nm.

[0075] In step S13, the method of peeling off the mask layer 12 is not limited, such as using tweezers or other tools to peel off the mask layer 12, or using organic solvents to dissolve and remove the mask layer 12.

[0076] In step S14, the metal layer 14 remaining on the substrate 10 in step S13 is used as a mask, and the substrate 10 is dry etched by reactive ion etching (RIE) to form a plurality of spaced protrusions 164 on the substrate 10, and the metal layer 14 remaining on the substrate 10 covers the plurality of protrusions 164. In this embodiment, the etching depth is 15 nm (nanometers), i.e. the height of the protrusions 164 is 15 nm.

[0077] In step S15, the metal layer 14 remaining on the substrate 10 is removed by etching solution. That is, the metal layer 14 remaining on the substrate 10 is removed by wet etching method. The type of etching solution is selected according to the different materials of the metal layer 14. In this embodiment, the metal layer 14 is a copper layer, and the etching solution is sulfuric acid, nitric acid, hydrochloric acid, or a mixed solution composed of hydrogen peroxide, hydrochloric acid and deionized water (the volume ratio of hydrogen peroxide, hydrochloric acid and deionized water is 1:1:50). In this embodiment, the plurality of protrusions 164 are arranged in order, the direction of the protrusions 164 in each row is defined as the X direction, and the direction of the protrusions 164 in each column is defined as the Y direction. That is, the protrusions 164 in each row are arranged along the X direction, and the protrusions 164 in each column are arranged along the Y direction. The shape of the protrusions 164 is not limited, which can be circular, square, triangular, etc. In this embodiment, the protrusions 164 are cylindrical, with a diameter of 40 nm and a height of 15 nm.

[0078] In step S16, the method of growing the graphene film 13 on the growth substrate 11 is not limited. In this embodiment, the process of growing the graphene film 13 on the growth substrate 11 is as follows: a catalyst layer is deposited on the growth substrate 11, then the growth substrate 11 with the deposited catalyst layer is put into a reaction chamber, carbon source gas is introduced, and the reaction chamber is heated to 800-1000°C, so as to grow the graphene film 13 on the growth substrate 11.

[0079] The material of the growth substrate 11 can be copper, and the size of the growth substrate 11 is not limited and can be selected according to actual needs. In this embodiment, the growth substrate 11 is a copper sheet.

[0080] A layer of metal or metal compound material is deposited on the surface of the growth substrate 11 to form the catalyst layer. The metal can be one or any combination of gold, silver, copper, iron, cobalt, and nickel. The metal compound can be one or any combination of zinc sulfide, zinc oxide, iron nitrate, iron chloride, and copper chloride. The method of depositing the catalyst layer on the growth substrate 11 is not limited, such as chemical vapor deposition, physical vapor deposition, vacuum thermal evaporation, magnetron sputtering, plasma-enhanced chemical vapor deposition, or printing, etc.

[0081] The reaction chamber is a closed cavity having an inlet and an outlet. The inlet is used to introduce a reaction gas, such as a carbon source gas, etc., and the outlet is connected to a vacuum pumping device. The vacuum pumping device controls the vacuum degree and gas pressure of the reaction chamber through the outlet. Further, the reaction chamber can also include a water cooling device and a heating device for controlling the temperature in the reaction chamber. In this embodiment, the reaction chamber is a quartz tube.

[0082] The carbon source gas can be methane, ethane, ethylene, acetylene, or the like. Non-oxidizing gas such as hydrogen can be introduced into the reaction chamber. Under the continuous introduction of non-oxidizing gas, when the temperature in the reaction chamber is 800-1000°C, the carbon source gas is cracked to deposit carbon atoms on the surface of the catalyst layer to form a graphene film 13. The gas flow rate of the carbon source gas is 20-90 sccm (standard cubic centimeter per minute), and the gas flow rate ratio of the non-oxidizing gas to the carbon source gas is 45:2-15:2. The reaction chamber can also be a vacuum environment with a gas pressure of 10-1-102 Pa. The constant temperature time for growing the graphene film 13 is 10-60 min. In this embodiment, the gas pressure in the reaction chamber is 500 mTorr, the reaction temperature is 1000°C, the carbon source gas is methane, the gas flow rate is 25 sccm, and the constant temperature time is 30 min.

[0083] The material of the adhesive layer 15 is not limited in step S17, and in this embodiment, the material of the adhesive layer 15 is PMMA (polymethyl methacrylate). The method of removing the growth substrate 11 is not limited, for example, the growth substrate 11 is removed by chemical etching. The material of the growth substrate 11 is copper, and the etching solution for removing the growth substrate 11 is sulfuric acid, nitric acid, hydrochloric acid, or a mixture of hydrogen peroxide, hydrochloric acid, and deionized water (the volume ratio of hydrogen peroxide, hydrochloric acid, and deionized water is 1:1:50). In this embodiment, the material of the growth substrate 11 is copper, and the etching solution for removing the growth substrate 11 is a mixture of hydrogen peroxide, hydrochloric acid, and deionized water (the volume ratio of hydrogen peroxide, hydrochloric acid, and deionized water is 1:1:50).

[0084] After removing the growth substrate 11, the residual impurities are removed by rinsing with water or an organic solvent. The water is preferably deionized water, and the type of the organic solvent is not limited, such as isopropyl alcohol, etc.

[0085] In step S18, during the process of taking out the graphene film 13 and the adhesive layer 15 from the water or organic solution by using the substrate 16, the substrate 16 is in direct contact with the graphene film 13, and the adhesive layer 15 is located on the surface of the graphene film 13 away from the substrate 16. Before drying, the water or organic solvent separates the graphene film 13 from the substrate 16, that is, there is water or organic solvent between the graphene film 13 and the substrate 16. As the water or organic solvent evaporates, a vacuum state gradually forms between the graphene film 13 and the substrate 16, and the graphene film 13 is thus tightly attached to the substrate 16. Because there are multiple protrusions 164 on the substrate body 162, the graphene film 13 cannot be flatly attached to the substrate body 162, and therefore wrinkles 18 are formed near the protrusions 164. The wrinkles 18 are located on the surface of the substrate body 162 between adjacent protrusions 164 and extend in the Y direction, and the thickness of the graphene film 13 at the wrinkles 18 is greater than the thickness of the graphene film 13 on the surface of the substrate body 162 between adjacent protrusions 164. In this embodiment, there are two layers of graphene film 13 at the wrinkles 18, and there is one layer of graphene film 13 on the surface of the substrate body 162 between adjacent protrusions 164. In this embodiment, after taking out the graphene film 13 and the adhesive layer 15 from the water or organic solution by using the substrate 16, the graphene film 13 is naturally dried for 3 to 6 hours, and then baked at a temperature of 150 degrees for 2 minutes. The distance between adjacent protrusions 164 in the Y direction is less than the distance between adjacent protrusions 164 in the X direction, so multiple wrinkles 18 are formed in the Y direction. The distance between adjacent protrusions 164 in the X direction is 200 nanometers to 1 micrometer, and the distance between adjacent protrusions 164 in the Y direction is 100 nanometers to 800 nanometers. In this embodiment, the distance between adjacent protrusions 164 in the X direction is 1 micrometer, and the distance between adjacent protrusions 164 in the Y direction is 500 nanometers.

[0086] In step S19, the method for removing the adhesive layer 15 is not limited, for example, the adhesive layer 15 can be dissolved and removed by using an organic solvent. The first composite structure 17 has one more adhesive layer 15 than the second composite structure 19. In the embodiment, the material of the adhesive layer 15 is PMMA, and the PMMA is removed by using acetone. Preferably, the adhesive layer 15 is removed by using an organic solvent, and after being taken out from the organic solution, annealing treatment is performed. The annealing treatment is to remove the residual adhesive layer 15 (for example, PMMA) on the surface of the graphene film 13 during the transfer process of the graphene film 13. In the embodiment, the annealing treatment is performed under the following conditions: hydrogen and argon are introduced under vacuum, the pressure is 2 Pa, and the annealing treatment is performed at 400°C for 2 hours.

[0087] In step S20, the graphene film 13 away from the surface of the substrate 16 is etched, so as to remove the graphene film 13 on the protrusions 164 and the graphene film 13 on the surface of the substrate body 162 between the adjacent protrusions 164 except the wrinkle 18. When the graphene film 13 on the surface of the substrate body 162 between the adjacent protrusions 164 except the wrinkle 18 is etched, the graphene film 13 on the wrinkle 18 is also etched. Since the thickness of the graphene film 13 on the wrinkle 18 is greater than the thickness of the graphene film 13 on the surface of the substrate body 162 between the adjacent protrusions 164, when the graphene film 13 on the surface of the substrate body 162 between the adjacent protrusions 164 except the wrinkle 18 is completely etched and removed, the graphene still exists on the wrinkle 18, so that the graphene nanoribbon 22 is obtained on each wrinkle 18. In the embodiment, the etching is performed by using RIE in step S21, and the etching conditions are as follows: the volume flow rate of hydrogen is 50 sccm, the pressure is 5 Pa, the power is 5 W, and the etching time is 50 s.

[0088] Further, the plurality of protrusions 164 can also be etched and removed. That is, the method for preparing the graphene nanoribbon composite structure 20 further comprises a step of etching and removing the plurality of protrusions 164.

[0089] Embodiment one

[0090] A silicon wafer with a 300 nm thick SiO2surface was used as the substrate 10. PMMA e-beam resist was spin-coated on the SiO2surface of the silicon wafer (i.e., the SiO2surface was in direct contact with the PMMA), to a thickness of 80 nm, and subjected to e-beam exposure and subsequent development. The exposed pattern was an array of vias with a diameter of 40 nm, a pitch of 500 nm between vias in each column, and a column-to-column pitch of 500 nm. The substrate 10 was then subjected to e-beam evaporation of 15 nm of copper, and the copper was removed using PG Remover solution to form an array of copper pillars with a diameter of 40 nm, a pitch of 500 nm between pillars in each column, and a column-to-column pitch of 500 nm. The substrate 10 was then etched using the array of copper pillars as a mask, and the copper pillars were removed to obtain a substrate 16 having an array structure. The protrusions 164 on the substrate 16 were cylindrical, with a diameter of 40 nm and a height of 15 nm. To transfer the graphene, PMMA was spin-coated onto a copper foil on which a single layer of graphene had been grown, at a speed of 3000 rpm, and then baked on a hot plate at 180°C for 2 minutes to evaporate the solvent. Since both surfaces of the copper foil were covered with graphene during the growth of the graphene, the graphene on the back surface of the copper foil was removed using reactive ion etching (RIE) under the following conditions: oxygen etching, a pressure of 2 Pa, a flow rate of 40 sccm, a power of 50 W, and an etching time of 30 seconds. The copper foil was then placed in an etching solution composed of hydrochloric acid, hydrogen peroxide, and water in a ratio of 1 : 1 : 50. After the copper foil was completely etched, the graphene and the PMMA film were washed several times with deionized water. The graphene and the PMMA film were then lifted using the substrate 16 having the array structure, and left to stand for 6 hours to allow the water to evaporate. The substrate 16 was then baked on a hot plate at 150°C for 2 minutes to obtain a sample. The sample was then placed in an acetone solution, left to stand for 10 minutes, and then removed. The sample was washed with deionized water and the surface water was blown off using nitrogen gas. Finally, the substrate 16 with the graphene was placed in an annealing furnace and annealed under the following conditions: 100 sccm of H2, 100 sccm of Ar, and 400°C for 2 hours, to obtain the graphene nanoribbon composite structure 20.

[0091] Figure 2 An atomic force microscope (AFM) image of the graphene film 13 and the adhesive layer 15 after they were removed from the water or organic solution using the substrate 16, dried, and the adhesive layer 15 was removed, i.e., an AFM image of the second composite structure 19. As shown in FIG. 6, the graphene film 13 was transferred onto the substrate 16 without any defects. Figure 2 As shown in FIG. 6, the graphene film 13 was transferred onto the substrate 16 without any defects.

[0092] Figure 3 Figure 2 is a scanning electron microscope (SEM) photo of the graphene nanoribbon composite structure 20 in step S20. Figure 4 Figure 3 is an atomic force microscope (AFM) photo of the graphene nanoribbon composite structure 20 in step S20. Figure 4 In the longitudinal direction, the strip structure between adjacent dots is the graphene nanoribbon 22. It can be seen that the plurality of graphene nanoribbons 22 are arranged at intervals and extend in the same direction and are parallel to each other.

[0093] Figure 2 is a scanning electron microscope (SEM) photo of the graphene nanoribbon composite structure 20 in step S20. Figure 4 and Figure 5 The present application further provides the graphene nanoribbon composite structure 20, which comprises the substrate 16 and the plurality of graphene nanoribbons 22 arranged at intervals on the substrate 16 and extending in the same direction. The substrate 16 comprises the substrate body 162 and the plurality of protrusions 164 arranged at intervals on the surface of the substrate body 162, and the graphene nanoribbons 22 are in direct contact with the substrate body 162. Each graphene nanoribbon 22 is located between two adjacent protrusions 164 and extends between the two protrusions 164, that is, the graphene nanoribbon 22 extends from one protrusion 164 to another protrusion 164. The plurality of graphene nanoribbons 22 are parallel to each other, and each graphene nanoribbon 22 is a strip structure or a one-dimensional linear structure. Further, when the plurality of protrusions 164 are etched and removed, the graphene nanoribbon composite structure is composed of the substrate body 162 and the plurality of graphene nanoribbons 22 and does not comprise the plurality of protrusions 164. The material of the substrate 16 is the same as that of the base 10.

[0094] Figure 2 is a scanning electron microscope (SEM) photo of the graphene nanoribbon composite structure 20 in step S20. Figure 2 、 Figure 5 and Figure 6 The second embodiment of the present application provides a preparation method of the graphene nanoribbon composite structure 20, which comprises the following steps:

[0095] S21, providing a substrate 16, which comprises a substrate body 162 and a plurality of protrusions 164 arranged at intervals on the surface of the substrate body 162;

[0096] S22, growing a graphene film 13 on a growth base 11;

[0097] S23, arranging an adhesive layer 15 on the surface of the graphene film 13 away from the growth base 11;

[0098] S24, removing the growth base 11 and cleaning with water or an organic solvent;

[0099] S25, the graphene film 13 and the adhesive layer 15 are taken out from the water or organic solution by using the substrate 16, and dried to obtain a first composite structure 17, the first composite structure 17 comprising the substrate 16, the graphene film 13 and the adhesive layer 15, the graphene film 13 being located between the adhesive layer 15 and the substrate 16, and the graphene film 13 being in direct contact with the protrusions 164;

[0100] S26, the adhesive layer 15 is removed to obtain a second composite structure 19, the second composite structure 19 comprising the substrate 16 and the graphene film 13, the graphene film 13 being located on the surface of the protrusions 164 and the surface of the substrate body 162 between adjacent protrusions 164, and the graphene film 13 forming a wrinkle 18 near the protrusions 164, the wrinkle 18 being located on the surface of the substrate body 162 between adjacent protrusions 164 and extending in the Y direction, and the thickness of the graphene film 13 at the wrinkle 18 being greater than the thickness of the graphene film 13 on the surface of the substrate body 162 between adjacent protrusions 164;

[0101] S27, etching is performed from the surface of the graphene film 13 away from the substrate 16 to remove the graphene film 13 on the protrusions 164 and the graphene film 13 on the surface of the substrate body 162 between adjacent protrusions 164 except for the wrinkle 18, thereby obtaining a graphene nanoribbon composite structure 20, the graphene nanoribbon composite structure 20 comprising the substrate body 162, the plurality of protrusions 164 and a plurality of mutually parallel graphene nanoribbons 22, the plurality of graphene nanoribbons 22 being arranged on the substrate body 162 in a spaced manner.

[0102] The second embodiment of the present application is similar to the first embodiment, and the difference is that, in the second embodiment, the preparation method of the substrate 16 is not limited, as long as the substrate 16 comprises a substrate body 162 and a plurality of protrusions 164 arranged in a spaced manner, and the plurality of protrusions 164 are arranged on the surface of the substrate body 162.

[0103] Please refer to Figure 2 、 Figure 5 and Figure 7 , the third embodiment of the present application provides a preparation method of a graphene nanoribbon composite structure 20, comprising the following steps:

[0104] S31, providing a substrate 16, the substrate 16 comprising a substrate body 162 and a plurality of protrusions 164 arranged in a spaced manner, the protrusions 164 being arranged on the surface of the substrate body 162;

[0105] S32, dropping water or an organic solvent on the surface of the protrusions 164 and the surface of the substrate body 162 between adjacent protrusions 164;

[0106] S33, a graphene film 13 is arranged on the surface of the substrate 16, and the protrusions 164 are located between the graphene film 13 and the substrate body 162, and dried, so that the graphene film 13 forms a wrinkle 18 near the protrusions 164, the wrinkle 18 is located on the surface of the substrate body 162 between adjacent protrusions 164 and extends in the Y direction, and the thickness of the graphene film 13 at the wrinkle 18 is greater than the thickness of the graphene film 13 on the surface of the substrate body 162 between adjacent protrusions 164;

[0107] S34, etching from the surface of the graphene film 13 away from the substrate 16, removing the graphene film 13 on the protrusions 164 and the graphene film 13 on the surface of the substrate body 162 between adjacent protrusions 164 except the wrinkle 18, thereby obtaining a graphene nanobelt composite structure 20, which comprises the substrate body 162, the plurality of protrusions 164 and a plurality of mutually parallel graphene nanobelts 22, which are arranged on the substrate body 162.

[0108] In step S32, the method of dropping water or organic solvent on the surface of the protrusions 164 and the surface of the substrate body 162 between adjacent protrusions 164 is not limited, for example, water or organic solvent is dropped on the surface of the protrusions 164 and the surface of the substrate body 162 between adjacent protrusions 164 by using a dropper. In this way, during the drying process, as the water or organic solvent evaporates, a vacuum state is gradually formed between the graphene film 13 and the substrate 16, and the graphene film 13 is thus closely attached to the substrate 16. Because there are a plurality of protrusions 164 on the substrate body 162, the graphene film 13 cannot be flatly attached to the substrate body 162, and therefore a wrinkle 18 is formed near the protrusions 164.

[0109] Further, in step S33, the graphene film 13 is arranged on the surface of the substrate 16 by using the adhesive layer 15, and the specific method is as described in the second embodiment of the present application, which will not be repeated here.

[0110] The third embodiment of the present application is similar to the first embodiment, and the difference is that: 1, in the third embodiment, the preparation method of the substrate 16 is not limited, as long as the substrate 16 comprises a substrate body 162 and a plurality of protrusions 164 arranged at intervals, and the plurality of protrusions 164 are arranged on the surface of the substrate body 162; 2, before the graphene film 13 is arranged on the surface of the substrate 16, water or organic solvent needs to be arranged on the surface of the protrusions 164.

[0111] Please refer to Figure 2 , Figure 5 and Figure 8 , the fourth embodiment of the present application provides a preparation method of a graphene nanobelt composite structure 20, comprising the following steps:

[0112] S41, providing a substrate 16, the substrate 16 comprising a substrate body 162 and a plurality of spaced protrusions 164, the protrusions 164 being arranged on a surface of the substrate body 162;

[0113] S42, arranging a graphene film 13 on the surface of the substrate 16 in an environment of water or organic solvent, and the protrusions 164 are located between the graphene film 13 and the substrate body 162, so that there is water or organic solvent between the substrate 16 and the graphene film 13, and then drying, so that the graphene film 13 forms a wrinkle 18 near the protrusions 164, the wrinkle 18 is located on the surface of the substrate body 162 between adjacent protrusions 164 and extends in the Y direction, and the thickness of the graphene film 13 at the wrinkle 18 is greater than the thickness of the graphene film 13 on the surface of the substrate body 162 between adjacent protrusions 164;

[0114] S43, etching from the surface of the graphene film 13 away from the substrate 16, removing the graphene film 13 on the protrusions 164 and the graphene film 13 on the surface of the substrate body 162 between adjacent protrusions 164 except the wrinkle 18, thereby obtaining a graphene nanoribbon composite structure 20, the graphene nanoribbon composite structure 20 comprising the substrate body 162, the plurality of protrusions 164 and a plurality of graphene nanoribbons 22, the plurality of graphene nanoribbons 22 being arranged on the substrate body 162.

[0115] Further, in step S42, the graphene film 13 is arranged on the surface of the substrate 16 by using the adhesive layer 15, and the specific method is as described in the second embodiment of the present application, which will not be repeated here.

[0116] The fourth embodiment of the present application is similar to the third embodiment, and the difference is that: a graphene film 13 is arranged on the surface of the substrate 16 in an environment of water or organic solvent, and the protrusions 164 are located between the graphene film 13 and the substrate body 162, so that there is water or organic solvent between the substrate 16 and the graphene film 13 before drying. Then when drying, with the evaporation of water or organic solvent, the graphene film 13 will form a wrinkle 18 near the protrusions 164.

[0117] Please refer to Figure 9 and Figure 11 , the fifth embodiment of the present application provides a preparation method of a top gate type field effect transistor 100, comprising the following steps:

[0118] S51, providing the graphene nanoribbon composite structure 20, the graphene nanoribbon composite structure 20 comprising the substrate 16 and a plurality of graphene nanoribbons 22, the plurality of graphene nanoribbons 22 being arranged on the substrate 16 and extending in the same direction;

[0119] S52, a source electrode 102 and a drain electrode 104 are formed at intervals at two ends of each graphene nanoribbon 22, and the source electrode 102 and the drain electrode 104 are electrically connected to the graphene nanoribbon 22;

[0120] S53, an insulating layer 106 is formed on surfaces of the plurality of graphene nanoribbons 22 away from the substrate 16; and

[0121] S54, a gate electrode 108 is formed on a surface of the insulating layer 106 away from the substrate 16, to obtain a field effect transistor 100.

[0122] In step S51, the method for preparing the graphene nanoribbon composite structure 20 has been described in detail in the first to fourth embodiments, and will not be repeated here. The plurality of graphene nanoribbons 22 are the semiconductor layer of the field effect transistor 100. The material of the substrate 16 is an insulating material, such as P-type or N-type silicon with a certain thickness of oxide layer, transparent quartz, or transparent quartz formed with an oxide layer, etc. In addition, the insulating material can also be a resin material, such as PET, etc.

[0123] In step S52, preferably, the source electrode 102 and the drain electrode 104 respectively cover the protrusions 164 and are in direct contact with the graphene nanoribbon 22. The graphene nanoribbon 22 has opposite first and second ends, the first end is in direct contact with the source electrode 102, and the second end is in direct contact with the drain electrode 104, as shown in Figure 10 .

[0124] The material of the source electrode 102 and the drain electrode 104 should have good conductivity. Specifically, the material of the source electrode 102 and the drain electrode 104 can be metal, alloy, indium tin oxide (ITO), antimony tin oxide (ATO), conductive silver paste, conductive polymer, and metallic carbon nanotube film, etc. The source electrode 102 and the drain electrode 104 can be formed by different methods according to the type of the material. Specifically, when the material of the source electrode 102 and the drain electrode 104 is metal, alloy, ITO or ATO, the source electrode 102 and the drain electrode 104 can be formed by evaporation, sputtering, deposition, masking and etching, etc. When the material of the source electrode 102 and the drain electrode 104 is conductive silver paste, conductive polymer or carbon nanotube film, the conductive silver paste or carbon nanotube film can be coated or adhered on the surface of the protrusion 164 by printing, coating or direct adhesion to form the source electrode 102 and the drain electrode 104. Generally, the thickness of the source electrode 102 and the drain electrode 104 is 0.5 nanometer to 100 micrometers, and the distance between the source electrode 102 and the drain electrode 104 is 10 nanometers to 800 nanometers. In this embodiment, the material of the source electrode 102 and the drain electrode 104 is metal, the thickness of the source electrode 102 and the drain electrode 104 is 50 nanometers, and the distance between the source electrode 102 and the drain electrode 104 is 150 nanometers.

[0125] In step S53, the material of the insulating layer 106 can be hard material such as silicon nitride or silicon oxide, or flexible material such as benzocyclobutene (BCB), polyester or acrylic resin. The insulating layer 106 can be formed by different methods according to the type of the material. Specifically, when the material of the insulating layer 106 is silicon nitride or silicon oxide, the insulating layer 106 can be formed by deposition. When the material of the insulating layer 106 is benzocyclobutene (BCB), polyester or acrylic resin, the insulating layer 106 can be formed by printing. Generally, the thickness of the insulating layer 106 is 0.5 nanometer to 100 micrometers.

[0126] In this embodiment, a silicon nitride insulating layer 106 is formed by deposition, which covers the plurality of graphene nanoribbons 22, the source electrode 102 and the drain electrode 104. The thickness of the insulating layer 106 is 50 nanometers.

[0127] In step S54, the material of the gate 108 should have good conductivity. Specifically, the material of the gate 108 can be a conductive material such as metal, alloy, ITO, ATO, conductive silver paste, conductive polymer, and carbon nanotube film. The metal or alloy material can be aluminum, copper, tungsten, molybdenum, gold, or an alloy thereof. Specifically, when the material of the gate 108 is metal, alloy, ITO, or ATO, the gate 108 can be formed by evaporation, sputtering, deposition, masking, etching, or the like. When the material of the gate 108 is conductive silver paste, conductive polymer, or carbon nanotube film, the gate 108 can be formed by direct adhesion or printing. Generally, the thickness of the gate 108 is 0.5 nm to 100 μm.

[0128] The gate 108 is electrically insulated from the plurality of graphene nanoribbons 22 by the insulating layer 106. In this embodiment, the material of the gate 108 is aluminum, and the thickness of the gate 108 is 50 nm.

[0129] Referring to Figure 11 The fifth embodiment of the present application further provides a field effect transistor 100 comprising the graphene nanoribbon composite structure 20, a source 102, a drain 104, an insulating layer 106, and a gate 108. The source 102 and the drain 104 are arranged at two ends of each graphene nanoribbon composite structure 20 and are electrically connected to the graphene nanoribbons 22. In this embodiment, the source 102 and the drain 104 are in direct contact with the graphene nanoribbons 22. The insulating layer 106 is arranged between the graphene nanoribbons 22 and the gate 108 and electrically insulates the graphene nanoribbons 22 from the gate 108. The insulating layer 106 also electrically insulates the source 102 and the drain 104 from the gate 108.

[0130] Referring to Figure 12 and Figure 13 The sixth embodiment of the present application provides a method for preparing a bottom-gate field effect transistor 200, comprising the following steps:

[0131] S61, providing the graphene nanoribbon composite structure 20 comprising the substrate 16 and a plurality of graphene nanoribbons 22 arranged on the substrate 16 and extending in the same direction;

[0132] S62, forming a source 102 and a drain 104 at two ends of each graphene nanoribbon 22 and electrically connecting the source 102 and the drain 104 to the plurality of graphene nanoribbons 22; and

[0133] S63, forming a gate 108 on the surface of the substrate 16 away from the graphene nanoribbons 22 to obtain a field effect transistor 200.

[0134] In step S61, the material of the substrate 16 is an insulating material. In step S63, the graphene nanoribbons 22 and the gate 108 are respectively located on the opposite surfaces of the substrate 16, and the substrate 16 corresponds to the insulating layer of the field effect transistor 200.

[0135] It can be understood that when the substrate 16 is a silicon wafer with a certain thickness of silicon oxide, and the graphene nanoribbons 22 are in direct contact with the silicon oxide, the step S63 can be omitted, and at this time, the silicon wafer corresponds to the gate 108 (silicon conductive) of the field effect transistor 200, and the silicon oxide corresponds to the insulating layer (silicon oxide non-conductive) of the field effect transistor 200. In the process of preparing the graphene nanoribbon composite structure 20, the substrate 10 is selected to be a silicon wafer with a certain thickness of silicon oxide, and the mask layer 12 is arranged on the silicon oxide, so as to obtain a silicon wafer substrate 16 with a certain thickness of silicon oxide, wherein the graphene nanoribbons 22 are in direct contact with the silicon oxide.

[0136] Please refer to Figure 13 The sixth embodiment of the present application further provides a field effect transistor 200, which comprises the graphene nanoribbon composite structure 20, a source 102, a drain 104 and a gate 108. The source 102 and the drain 104 are arranged at the two ends of each graphene nanoribbon 22 and are electrically connected with the graphene nanoribbon 22. The material of the substrate 16 is an insulating material. In this embodiment, the source 102, the drain 104 and the graphene nanoribbon 22 are in direct contact. The gate 108 is arranged on the surface of the substrate 16 away from the graphene nanoribbon composite structure 20.

[0137] It can be understood that when the substrate 16 in the graphene nanoribbon composite structure 20 is a silicon wafer with silicon oxide, and the graphene nanoribbons 22 are arranged on the silicon oxide, the gate 108 can be omitted, and the silicon wafer can serve as the gate 108 of the field effect transistor 200, and the silicon oxide can serve as the insulating layer of the field effect transistor.

[0138] The sixth embodiment of the present application is similar to the fifth embodiment, and the difference is that the fifth embodiment is a top-gate field effect transistor, and the sixth embodiment is a bottom-gate field effect transistor.

[0139] Please refer to Figure 14 and Figure 15 The seventh embodiment of the present application provides a preparation method of a field effect transistor 300, which comprises the following steps:

[0140] S71, providing the graphene nanoribbon composite structure 20, which comprises the substrate 16 and a plurality of graphene nanoribbons 22, the plurality of graphene nanoribbons 22 being arranged on the substrate 16 in a spaced manner and extending in the same direction;

[0141] S72, disposing a first electrode 212 and a second electrode 214 on the surface of the graphene nanoribbon composite structure 20, the first electrode 212 and the second electrode 214 covering the plurality of protrusions 164 and being electrically connected with the plurality of graphene nanoribbons 22.

[0142] In step S71, the substrate 16 in the graphene nanoribbon composite structure 20 is a silicon wafer with silicon oxide, and the graphene nanoribbons 22 are disposed on the silicon oxide and directly contact the silicon oxide.

[0143] In step S72, the interdigital electrode 210 includes a first electrode 212 and a second electrode 214. The first electrode 212 includes a plurality of first sub-electrodes 2120, and the second electrode 214 includes a plurality of second sub-electrodes 2140. The plurality of first sub-electrodes 2120 and the plurality of second sub-electrodes 2140 are spaced and alternately disposed on the surface of the graphene nanoribbon composite structure 20, and the plurality of first sub-electrodes 2120 and the plurality of second sub-electrodes 2140 cover the plurality of protrusions 164 and are electrically connected with the plurality of graphene nanoribbons 22. Preferably, the plurality of first sub-electrodes 2120 directly contact the plurality of graphene nanoribbons 22, and the plurality of second sub-electrodes 2140 directly contact the plurality of graphene nanoribbons 22. The extension direction of the plurality of first sub-electrodes 2120 is perpendicular to the extension direction of the plurality of graphene nanoribbons 22, and the extension direction of the plurality of second sub-electrodes 2140 is perpendicular to the extension direction of the plurality of graphene nanoribbons 22. The plurality of first sub-electrodes 2120 are electrically connected with each other, and the plurality of second sub-electrodes 2140 are electrically connected with each other. Specifically, the plurality of first sub-electrodes 2120 are electrically connected by a connecting portion 2122, and the plurality of second sub-electrodes 2140 are electrically connected by a connecting portion 2122, as shown in FIG. 2B. The connecting portion 2122 serves the function of electrical connection and is made of conductive material, such as metal and the like. It can be understood that the connecting portion 2122 can be integrally formed with the plurality of first sub-electrodes 2120, and the connecting portion 502 can be integrally formed with the plurality of second sub-electrodes 2140, thereby forming the interdigital electrode 210. The materials of the first electrode 212 and the second electrode 214 are the same as those of the source electrode 102 and the drain electrode 104. Figure 15

[0144] Please refer to Figure 16 ​The seventh embodiment of the present application further provides a field effect transistor 300 comprising the graphene nanoribbon composite structure 20 and the interdigital electrode 210, wherein the interdigital electrode 210 is arranged on the surface of the graphene nanoribbon composite structure 20 and is electrically connected with the graphene nanoribbons 22. Specifically, a plurality of first sub-electrodes 2120 and a plurality of second sub-electrodes 2140 are arranged alternately and are spaced apart on the surface of the graphene nanoribbon composite structure 20, and the plurality of first sub-electrodes 2120 and the plurality of second sub-electrodes 2140 cover the plurality of protrusions 164 and are in direct contact with the plurality of graphene nanoribbons 22. The substrate 16 in the graphene nanoribbon composite structure 20 is a silicon wafer with silicon oxide, and the graphene nanoribbons 22 are arranged on the silicon oxide and are in direct contact with the silicon oxide. The silicon wafer serves as the gate of the field effect transistor 300, and the silicon oxide serves as the insulating layer of the field effect transistor 300.

[0145] The field effect transistor 100, 200, 300 and the preparation method thereof have the following advantages: first, in the field effect transistor 100, 200, 300 provided by the present application, the semiconductor layer is a plurality of graphene nanoribbons 22 arranged in order, which are obtained by combining the graphene film 13 with the substrate 16 having a plurality of protrusions 164, setting water or an organic solvent on the substrate 16 before the combination, forming the wrinkle 18 near the protrusions 164, and further etching the graphene film 13; second, the field effect transistor 100, 200, 300 can be prepared in a large area, and the cost and energy consumption are low.

[0146] In addition, those skilled in the art can make other changes within the spirit of the present application, and of course, these changes made according to the spirit of the present application should be included in the scope of protection required by the present application.

Claims

1. A method for fabricating a field-effect transistor, comprising the following steps: A graphene nanoribbon composite structure is provided, comprising: providing a substrate, the substrate including a substrate body and a plurality of protrusions spaced apart on the surface of the substrate body; defining an X direction and a Y direction on the surface of the substrate body, the X direction being perpendicular to the Y direction, the distance between adjacent protrusions in the Y direction being less than the distance between adjacent protrusions in the X direction; depositing a graphene film on the surface of the substrate in an environment of water or organic solvent, with the protrusions located between the graphene film and the substrate body, such that water or organic solvent is present between the substrate and the graphene film, followed by drying, and utilizing the... The evaporation of water or organic solvent causes the graphene film to form wrinkles with a greater thickness than other regions between adjacent protrusions, and the graphene film forms wrinkles near each protrusion; and etching is performed from the side of the graphene film away from the substrate, using the thickness difference between the wrinkles and other regions to selectively remove the graphene film in the other regions, retaining the graphene film at the wrinkles and forming a plurality of graphene nanoribbons extending along the Y direction, thereby obtaining a graphene nanoribbon composite structure, the graphene nanoribbon composite structure including the substrate and the plurality of graphene nanoribbons, the plurality of graphene nanoribbons being spaced apart on the substrate; A source and a drain are formed at intervals at both ends of each graphene nanoribbon, and the source and drain are electrically connected to the graphene nanoribbon. An insulating layer is formed on the surface of the plurality of graphene nanoribbons away from the substrate; and A gate is formed on the surface of the insulating layer away from the substrate.

2. The method for fabricating a field-effect transistor as described in claim 1, characterized in that, The method for preparing the substrate includes the following steps: A mask layer is disposed on a substrate, the mask layer having opposing first and second surfaces, the first surface being in contact with the substrate, and the mask layer having a plurality of spaced-apart through holes; A metal layer is disposed on the second surface, and the metal layer fills the through hole; When the mask layer is peeled off, the metal layer on the second surface of the mask layer is also removed at the same time, while the metal layer inside the through hole remains on the substrate. Using the metal layer retained on the substrate as a mask, the substrate is etched; and The metal layer remaining on the substrate is removed to obtain the substrate.

3. The method for fabricating a field-effect transistor as described in claim 1, characterized in that, As the water or organic solvent evaporates, a vacuum is formed between the graphene film and the substrate. Since the substrate has multiple protrusions, the graphene film cannot adhere smoothly to the substrate, thus forming wrinkles near each protrusion.

4. The method for fabricating a field-effect transistor as described in claim 1, characterized in that, The source and drain electrodes respectively cover the plurality of protrusions and are in direct contact with the plurality of graphene nanoribbons.

5. The method for fabricating a field-effect transistor as described in claim 1, characterized in that, Depositing a graphene film on the surface of a substrate in an aqueous or organic solvent environment includes the step of first adding water or an organic solvent to the surface of the substrate, and then depositing a graphene film on the surface of the substrate.

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