Double-layer graphene terahertz detector based on vertical butterfly-shaped coupled antenna and preparation method of double-layer graphene terahertz detector

Abstract

The invention discloses a double-layer graphene terahertz detector based on a vertical butterfly-shaped coupled antenna and a preparation method of the double-layer graphene terahertz detector. The terahertz detector comprises a silicon substrate; the silicon dioxide supporting layer is attached to the upper surface of the silicon substrate; the bottom grid is embedded into the upper surface layer of the silicon dioxide supporting layer or attached to the upper surface of the silicon dioxide supporting layer and comprises a wing-shaped antenna part and a rectangular antenna part; the top gate is arranged above the silicon dioxide supporting layer in parallel and comprises a wing-shaped antenna part and a rectangular antenna part; the bottom grid and the top grid jointly form a bowknot structure, and the rectangular antenna parts of the bottom grid and the top grid are semi-staggered and semi-overlapped along the width direction; the graphene part is a rectangular antenna part which is vertically connected with the bottom grid and the top grid and comprises a wrapping layer, a double-layer graphene layer and a wrapping layer from bottom to top; the source electrode and the drain electrode are connected to the left end and the right end of the graphene part respectively. According to the terahertz detector, terahertz detection can be realized at room temperature, and the size of the detector is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the field of terahertz detection technology, and in particular to a double-layer graphene terahertz detector based on a vertical butterfly-shaped coupling antenna and a preparation method thereof. Background Art

[0002] Graphene is a widely studied two-dimensional atomic crystal with linear bandgap and zero bandgap. It has ultra-high carrier mobility at room temperature, ultra-fast photoelectron relaxation speed (1ps), and ultra-wideband absorption spectrum (from visible light to infrared to terahertz range). Due to its excellent electronic and optical properties, it has become a hot spot in the research of photoelectric detection technology, especially the high carrier mobility and wide spectral absorption range at room temperature. However, in the field of terahertz wave detection, the application of graphene still faces challenges. Its light absorption rate is relatively low, which limits the responsivity of graphene-based detection devices. There are also studies focusing on the design of antenna structures for enhanced external absorption and the integration of graphene materials with these structures. In addition, there are also designs for graphene as a channel material, such as integrating double-layer graphene (BLG) on different substrates for enhanced absorption. BLG is a narrow-band semiconductor with a tunable band structure that is highly sensitive to the lateral electric field. This ensures a steep bipolar field effect and allows independent control of the bandgap size and carrier density. BLG also has a high-mobility electronic system, which is a key feature for high-frequency applications. There are currently a variety of terahertz detectors designed based on BLG materials. There are tunnel field-effect transistors made of double-layer graphene (BLG), which can use the electrically tunable band structure of BLG to create a lateral tunnel junction, which has high responsiveness and low noise characteristics at low temperatures. There are also terahertz detectors prepared based on the principle of graphene plasma resonance, which provides a feasible way for the development of graphene terahertz detectors at room temperature.

[0003] In 2020, Tu Xuecou et al. proposed a bow-tie antenna coupled terahertz detector (CN 112577613A). The thermal conductivity of the device was reduced to the limit by designing the contact connection shape between the antenna and the hexanitrogen pentaniobium film, thereby improving the detection performance of the device. This method is based on reducing the thermal conductivity of the device. The size of the thermosensitive material hexanitrogen pentaniobium nanobridge is at the nanometer level, and the length and width are controlled in the range of tens of nm. The processing accuracy requirements are high and the detection performance of this design at room temperature is currently unknown.

[0004] In 2021, Xu Youlong and others proposed a graphene-based antenna-enhanced terahertz detector and its preparation method (CN13764858 A). The collaborative joint antenna designed in this invention uses a logarithmic periodic antenna as the source-drain antenna of the transistor detector, and adds a rectangular patch antenna corresponding to the detection frequency at the gate. The two antennas work together to introduce the terahertz signal of the target frequency band into the channel to enhance the detection performance. However, the antenna size of this design is large and is in the theoretical design simulation stage. The impact of detection performance in non-environmental conditions during this period is not considered.

[0005] In summary, the current application of single-layer graphene in photodetectors is because graphene has a large bandwidth. However, graphene photodetectors are limited by their low light responsivity due to their weak light absorption, and most of the high-sensitivity graphene terahertz detection devices reported so far have the characteristics of high sensitivity and low noise at extremely low temperatures. There are few designs of terahertz detection devices at room temperature, and the detection capability of devices at room temperature is reduced. Some devices are actually in the theoretical simulation stage due to the difficulty of processing, which further limits the practical application of graphene terahertz detection devices. Therefore, high-sensitivity and low-cost terahertz detectors at room temperature are still in short supply, and it is still necessary to continue to explore new material systems, device structures and corresponding new detection mechanisms. Summary of the invention

[0006] The purpose of the present invention is to provide a double-layer graphene terahertz detector based on a vertical butterfly-shaped coupling antenna and a preparation method thereof. The present invention further processes and designs the detection material, i.e., the double-layer graphene, based on enhanced external absorption, and adopts a design structure of a vertical butterfly-shaped coupling antenna, which can realize terahertz detection at room temperature and effectively reduce the size of the detection device.

[0007] In a first aspect, the present invention provides a double-layer graphene terahertz detector based on a vertical butterfly coupling antenna, comprising:

[0008] Silicon substrate;

[0009] A silicon dioxide support layer attached to the upper surface of the silicon substrate;

[0010] A bottom grid embedded in the upper surface of the silicon dioxide support layer or attached to the upper surface of the silicon dioxide support layer includes a wing-shaped antenna portion and a rectangular antenna portion extending from the root of the wing-shaped antenna;

[0011] A top gate arranged in parallel above the silicon dioxide support layer comprises a fin-shaped antenna portion and a rectangular antenna portion extending from the root of the fin-shaped antenna;

[0012] The bottom grid and the top grid together form a bow-tie structure in the horizontal direction, wherein the rectangular antenna portion of the bottom grid and the rectangular antenna portion of the top grid are parallel along the length direction of the rectangular antenna and half-staggered and half-overlapped along the width direction of the rectangular antenna;

[0013] A graphene component, which connects the rectangular antenna part of the bottom grid and the rectangular antenna part of the top grid from top to bottom, comprises a wrapping layer, a double-layer graphene layer and a wrapping layer of a sandwich structure from bottom to top, and the size of the graphene component along the length direction of the rectangular antenna does not exceed the rectangular antenna parts of the bottom grid and the top grid;

[0014] A source electrode and a drain electrode are respectively connected to the left and right ends of the graphene component.

[0015] In the above-mentioned double-layer graphene terahertz detector based on vertical butterfly coupling antenna, along the length direction of the rectangular antenna, the graphene component is close to but not in contact with the wing-shaped antenna parts of the bottom grid and the top grid;

[0016] A dimension of the double-layer graphene component along a length direction of the rectangular antenna is smaller than a dimension of the double-layer graphene component along a width direction of the rectangular antenna.

[0017] In the above-mentioned double-layer graphene terahertz detector based on vertical butterfly coupling antenna, the bottom gate is embedded in the upper surface layer of the silicon dioxide support layer, the thickness of the silicon dioxide layer is greater than 50nm, and the bottom gate and the top gate each include a 3-5nm thick chromium layer and a 40-45nm thick gold layer from bottom to top.

[0018] In the above-mentioned double-layer graphene terahertz detector based on vertical butterfly coupling antenna, the bottom grid is attached to the upper surface of the silicon dioxide support layer, and the rectangular antenna parts of the bottom grid and the top grid are both made of transparent semiconductor materials, preferably multilayer graphene.

[0019] In the above-mentioned double-layer graphene terahertz detector based on vertical butterfly coupling antenna, the thickness of the wrapping layer is 15nm to 30nm;

[0020] The material of the wrapping layer is boron nitride, hafnium oxide or aluminum oxide.

[0021] In the above-mentioned double-layer graphene terahertz detector based on vertical butterfly coupling antenna, the source electrode and the drain electrode are asymmetric structures;

[0022] The source electrode and the drain electrode are close to each other but do not contact the rectangular antenna portion of the bottom gate and the top gate;

[0023] The source electrode and the drain electrode are made of gold or chromium.

[0024] In a second aspect, the present invention provides a method for preparing a double-layer graphene terahertz detector based on a vertical butterfly coupling antenna as described in any one of the above, comprising the following steps:

[0025] S1, providing double-layer graphene and a wrapping layer material;

[0026] S2, spin coating photoresist on the silicon dioxide surface of the silicon substrate provided with a silicon dioxide support layer, exposing the photoresist according to a preset pattern of the bottom gate to obtain a pattern of the bottom gate;

[0027] Etching the bottom gate pattern without photoresist protection, depositing a metal film on the surface of the etched product, removing the metal film in the area covered by the photoresist, and obtaining a bottom gate embedded in the upper surface layer of the silicon dioxide support layer or attached to the surface of the silicon dioxide support layer;

[0028] S3, placing the double-layer graphene and the wrapping layer material on the rectangular antenna portion of the bottom grid in the product obtained in step S2 to form the graphene component;

[0029] S4, spin-coating a photoresist on the surface of the product obtained in step S3, exposing the photoresist according to a preset pattern of the top gate, and obtaining a pattern of the top gate;

[0030] Etching the pattern of the top gate without photoresist protection, depositing a metal film on the surface of the etched product, removing the metal film in the area covered by the photoresist, and obtaining a top gate arranged on the graphene component;

[0031] S5, modifying the shape of the graphene component in the product obtained in step S4, and removing the portion that exceeds the length direction of the rectangular antenna;

[0032] S6, spin-coating a photoresist on the surface of the product obtained in step S5, exposing the photoresist according to a preset pattern of the source electrode and the drain electrode, and obtaining patterns of the source electrode and the drain electrode;

[0033] The source electrode and the drain electrode without photoresist protection are etched, a metal film is deposited on the surface of the etched product, and the metal film in the area covered by the photoresist is removed to obtain the source electrode and the drain electrode connected to the two ends of the graphene component.

[0034] In the above-mentioned method for preparing a double-layer graphene terahertz detector based on a vertical butterfly coupling antenna, when the material of the wrapping layer is boron nitride, the method for preparing the graphene component comprises the following steps:

[0035] (a) spin coating a polypropylene carbonate solution on a silicon wafer and baking to form a PPC film on the silicon wafer;

[0036] (b) peeling off the PPC film on the silicon wafer by means of a perforated tape, and placing the PPC film tape on a polydimethylsiloxane block on a transparent glass sheet to fix it, thereby obtaining a protruding structure;

[0037] (c) The protruding structure is used to first pick up the boron nitride peeled off on the silicon substrate, then pick up the double-layer graphene on the silicon wafer through the boron nitride, and finally pick up the boron nitride again to form the graphene component.

[0038] In a third aspect, the present invention provides a method for improving terahertz detection sensitivity, comprising the following steps:

[0039] In the terahertz detection process, an electric field is applied to the bottom gate and the top gate of the double-layer graphene terahertz detector based on the vertical butterfly coupling antenna described in any one of the above items to obtain a photocurrent response and calculate the photoresponsivity;

[0040] According to the light response, the structure of the double-layer graphene terahertz detector is adjusted to improve the detection sensitivity at room temperature.

[0041] In a fourth aspect, the present invention provides a modulation method for photoelectric detection of a terahertz detector, comprising the following steps:

[0042] In the terahertz detection process, the polarization direction of the incident light of the double-layer graphene terahertz detector based on the vertical butterfly coupling antenna described in any one of the above items is adjusted to achieve modulation of photoelectric detection at room temperature.

[0043] The present invention has the following beneficial effects:

[0044] (1) The present invention provides a terahertz detector design based on double-layer graphene band regulation and terahertz signal reception. The design structure of the vertical butterfly-shaped coupling antenna is adopted to couple the terahertz signal to the detection material, that is, the double-layer graphene, to achieve the enhancement effect of the terahertz field in the device. At the same time, the terahertz electric field opens the double-layer graphene band gap and changes the resistance of the device. The above two effects are superimposed to achieve the detection of terahertz waves by graphene. The antenna is vertically separated and half-staggered and overlapped. By applying gate voltage to the left and right antenna half arms at the same time, the carrier concentration in the BLG in the overlapping area is simultaneously regulated by the top gate and the bottom gate, thereby achieving the opening of the band gap. The BLG on the left and right sides of the overlapping area is only regulated by the top gate or the bottom gate, thereby completing the construction of the pn junction in the BLG and inducing the generation of photocurrent of the photothermoelectric effect. Thereby, the detection of terahertz signals by the enhanced device at room temperature is achieved. In addition, the design also minimizes the impact on the device performance and reduces the size of the antenna, thereby reducing the size of the device.

[0045] (2) The present invention can further regulate the doping concentration on both sides of the junction region by applying an electric field at both ends of the bottom gate and top gate antennas of the terahertz detector device, thereby further improving the sensitivity of terahertz detection, thereby achieving a wide range of regulation of the band gap of double-layer graphene and realizing terahertz detection based on the photovoltaic effect or photothermoelectric (PTE) effect in graphene at room temperature.

[0046] (3) The terahertz device of the present invention has polarization characteristics. The photoelectric response of the device is related to its geometric shape and structure. The modulation of photoelectric detection can be achieved by adjusting the polarization direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the overall structure of a double-layer graphene terahertz detector based on a vertical butterfly-shaped coupling antenna provided by an embodiment of the present invention and a schematic diagram of the structure of the graphene components therein, with a top view on the left and a side view on the right.

[0048] Figure 2 It is a schematic diagram of the overall structure of a double-layer graphene terahertz detector based on a vertical butterfly-shaped coupling antenna provided by another embodiment of the present invention and a schematic diagram of the structure of the graphene components therein, with a left-top view and a right-side view.

[0049] Figure 3 : is a schematic diagram of the working principle of a double-layer graphene terahertz detector based on a vertical butterfly coupling antenna provided by an embodiment of the present invention, wherein: Figure 3 a is the absorption of terahertz waves by the two-end device of double-layer graphene. Figure 3 b is a control diagram of adding vertically separated and partially offset top and bottom gates to the double-layer graphene two-terminal device. Figure 3 c is a device with a butterfly antenna and terahertz wave enhanced absorption structure added to the above device.

[0050] Figure 4 Schematic diagram of a source electrode and a drain electrode with an asymmetric structure provided by an embodiment of the present invention.

[0051] Figure 5 The present invention is a device processing flow chart of a double-layer graphene terahertz detector based on a vertical butterfly coupling antenna provided by an embodiment of the present invention, and each figure is represented as follows: Figure (1) coating and development; Figure (2) RIE etching; Figure (3) evaporation coating; Figure (4) stripping of metal film; Figure (5) transferring a double-layer graphene sandwich structure; Figure (6) coating and development; Figure (7) evaporation coating; Figure (8) stripping of metal film; Figure (9) coating and development; Figure (10) RIE etching; Figure (11) evaporation coating; Figure (12) stripping of metal film;

[0052] Figure 6This is a flowchart of the processing and transfer of a graphene component sandwich structure in a double-layer graphene terahertz detector based on a vertical butterfly coupling antenna provided by an embodiment of the present invention, and the figures are as follows: Figure (13) transparent glass sheet; Figure (14) spin coating of PPC solution and drying at 90 degrees Celsius; Figure (15) punching tape; Figure (16) PDMS; Figure (17) fixing with transparent tape; Figure (18) placing punching tape on the structure of Figure (17); Figure (19) picking up boron nitride with structure 18; Figures (20)-(21) picking up double-layer graphene with the picked-up boron nitride; Figures (22)-(23) picking up boron nitride again in the same way; (24) transferring the graphene sandwich to the structure of Figure (4); (25) completing the processing and transfer of the graphene component sandwich structure.

[0053] Figure 7 This is the Raman spectrum of double-layer graphene.

[0054] Figure 8 is a diagram showing the actual processing process of the double-layer graphene terahertz detector based on the vertical butterfly coupling antenna prepared in Example 1 of the present invention, wherein: Figure 8 (a) is an optical microscope photo of the bottom-gate antenna; Figure 8 (b) Placing the sandwich stack hBN / BLG / hBN on the bottom grid antenna; Figure 8 (c) is an optical photograph of the bottom gate, BLG stack and top gate under a 100x objective lens; Figure 8 (d) Modified graphene channel.

[0055] Fig. 9 This is an optical photograph of the double-layer graphene terahertz detector based on the vertical butterfly-shaped coupling antenna prepared in Example 1 of the present invention under a 100-fold objective lens.

[0056] Fig.10 is the electrical characteristic measurement result of the double-layer graphene terahertz detector device based on the vertical butterfly coupling antenna prepared in Example 1 of the present invention, wherein: Fig.10 (a) is the relationship between resistivity ρ and carrier density n; Fig.10 (b) is the relationship between the resistance R and the dual-gate voltage, and the dotted line represents Fig.10 The data in (a).

[0057] Fig.11 (a) is the relationship between the photocurrent Iph and the two gate voltages under 2.7 THz radiation; (b) is the relationship curve between the photocurrent and the incident power, where the blue circles are experimental data.

[0058] Fig.12 is a graph of the relationship between the device's photocurrent and the polarization angle of the incident light.

[0059] The marks in the figure are as follows:

[0060] 1-silicon substrate; 2-silicon dioxide support layer; 3-bottom gate; 4-top gate; 5-graphene component; 6-wrapping layer; 7-double-layer graphene layer; 8-source electrode; 9-drain electrode;

[0061] A-A'-length direction of rectangular antenna; B-B'-width direction of rectangular antenna; C-C'-vertical direction;

[0062] 10- terahertz wave; 11- multilayer graphene rectangular bottom grid; 12- multilayer graphene rectangular top grid;

[0063] 13-external electrode and pad of bottom gate electrode; 14-external electrode and pad of bottom gate electrode; 15-epitaxial electrode and pad of source electrode, 16-epitaxial electrode and pad of drain electrode; in Figures 13 to 16, the pads are 5nm chromium and 45nm gold deposited by evaporation. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] In the description of the present invention, it should be noted that the terms "up", "down", "horizontal", "vertical", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0066] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "assembly", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] As described in the background technology, how to provide a high-sensitivity, small-size, low-cost graphene terahertz detector at room temperature is still a technical problem that needs to be solved urgently. Based on this, the first part, such as Figure 1-Figure 2As shown, the present invention provides a double-layer graphene terahertz detector based on a vertical butterfly-shaped coupling antenna, comprising: a silicon substrate 1; a silicon dioxide support layer 2 attached to the upper surface of the silicon substrate 1; a bottom grid 3 embedded in the upper surface layer of the silicon dioxide support layer 2 or attached to the upper surface of the silicon dioxide support layer, comprising a wing-shaped antenna part and a rectangular antenna part extending from the root of the wing-shaped antenna (with the extension direction being the length direction of the rectangular antenna part); a top grid 4 arranged in parallel above the silicon dioxide support layer 2, comprising a wing-shaped antenna part and a rectangular antenna part extending from the root of the wing-shaped antenna (with the extension direction being the length direction of the rectangular antenna part); the bottom grid 3 and the top grid 4 are coaxial in the horizontal direction. The bow-tie structure is formed together, wherein the rectangular antenna part of the bottom gate 3 and the rectangular antenna part of the top gate 4 are parallel along the length direction A-A' of the rectangular antenna, and are half-staggered and half-overlapped along the width direction B-B' of the rectangular antenna; a graphene component 5, which connects the rectangular antenna part of the bottom gate 3 and the rectangular antenna part of the top gate 4 from top to bottom, comprises a wrapping layer 6, a double-layer graphene layer 7 and a wrapping layer 6 of a sandwich structure from bottom to top (along the C-C' direction), and the size of the graphene component 4 along the length direction A-A' of the rectangular antenna does not exceed the rectangular antenna part of the bottom gate 3 and the top gate 4; a source electrode 8 and a drain electrode 9 are respectively connected to the left and right ends of the graphene component.

[0068] Based on the above technical scheme, the present invention adopts a double-layer graphene design of a vertical butterfly-shaped coupling antenna, wherein the role of the Bowtie antenna when the device is working is as follows: on the one hand, the bowtie antenna converges the incident terahertz wave into the BLG (double-layer graphene), enhancing the absorption of light waves in different bands including the terahertz wave band; on the other hand, the antenna is vertically separated and half-staggered and overlapped, and the carrier concentration in the BLG in the overlapping area is simultaneously regulated by the top gate and the bottom gate by applying gate voltage to the left and right antenna half arms at the same time, thereby realizing the opening of the band gap, and the BLG on the left and right sides of this overlapping area is only regulated by the top gate or the bottom gate, thereby completing the construction of the pn junction in the BLG, inducing the generation of photocurrent of the photothermoelectric effect; thereby achieving the enhancement of the detection performance of the device in different bands at room temperature. At the same time, the present invention reduces the size of the antenna while minimizing the impact on the performance of the device, thereby reducing the size of the device.

[0069] like Figure 3As shown, coupling the terahertz signal to the detection material, i.e., double-layer graphene, can achieve the enhancement effect of the terahertz field in the device. At the same time, the terahertz electric field opens the band gap of the double-layer graphene and changes the resistance of the device. The above two effects are superimposed, thereby realizing the detection of terahertz waves by graphene. The double-layer graphene is integrated into the vertically discrete metal antenna structure. The rectangular structure led out by the upper and lower metal antennas partially overlaps and is discrete. The overlapping part can be dual-gate regulated at the same time to independently regulate the electronic band gap and carrier doping concentration; while the discrete part is an asymmetric design, which not only enhances the optical absorption of the detector but also achieves the purpose of pn regulation of the graphene material to induce the generation of photocurrent by the photothermoelectric effect. At the same time, since the wavelength of the terahertz wave is much larger than the device size, most of the incident terahertz wave is reflected or transmitted, and only a small part is absorbed by the BLG and used for detection. The introduction of the antenna can effectively scale the size of the detection device and enhance graphene's absorption of different light wavelengths (including terahertz), so as to realize terahertz detection of small-sized devices at room temperature.

[0070] The present invention is a terahertz detector based on double-layer graphene band regulation and terahertz signal reception. First, unlike the design principle of reducing the thermal conductivity of the device to the limit level in the current terahertz detector, the present invention is based on the use of an antenna-gate integrated offset overlap structure that can simultaneously use a double gate to regulate the graphene material, use a bow-tie antenna to implement the reception of light waves of different bands including terahertz signals, and couple the terahertz wave to the graphene material through the rectangular lead part of the antenna. The antenna converges the terahertz wave to achieve high-precision overlap between the generation area and the separation area of ​​photogenerated carriers, thereby effectively increasing the generation and separation efficiency of photogenerated carriers, and then realizing the terahertz measurement of the device at room temperature; secondly, unlike the current terahertz detectors that are mostly designed based on the mechanism of enhancing external absorption, the design scheme of the present invention is to give the antenna as a gate to regulate the graphene material on this mechanism. That is, the optical absorption of the detector is enhanced and the purpose of pn regulation of the graphene material is achieved at the same time, inducing the generation of photocurrent of the photothermoelectric effect. The present invention uses the photothermoelectric effect of graphene as a theoretical basis and combines the antenna design with a wide spectrum including the terahertz band to realize the design of a terahertz detector at room temperature. It can also be said that the terahertz detector of the present invention is a dual-gated graphene terahertz detector device based on a butterfly-type coupled antenna and a field-effect transistor.

[0071] In the above embodiment, preferably, along the length direction A-A' of the rectangular antenna, the graphene component 5 is close to but does not contact the wing-shaped antenna part of the bottom gate 3 and the top gate 4. This is because if the distance is far, the terahertz wave will propagate in the metal rectangular gate and there will be loss. The design of the component 5 being infinitely close to non-contact achieves the double-gate regulation function under the premise of avoiding reducing the absorption of the terahertz wave by the detection device. Preferably, the size of the double-layer graphene component along the length direction A-A' of the rectangular antenna is smaller than the size of the double-layer graphene component along the width direction B-B' of the rectangular antenna. The terahertz wave in the rectangular structure is continuously absorbed by the graphene component during transmission. The excessive length of the graphene in the length direction may cause a significant reduction in the absorption of terahertz waves in some devices (the farther the distance, the greater the loss of terahertz waves). The double-gate regulation part of the detection device is a field effect transistor. The width-to-length ratio of the source-drain electrode is an important parameter affecting the performance of the field effect transistor, affecting the size of the parasitic capacitance and the current driving capability between the source and the drain. For example, the size of the double-layer graphene along the length direction AA' (longitudinal direction) of the rectangular antenna is about 2 μm (not too long, and needs to be smaller than the width of the double-layer graphene between the source and drain).

[0072] In an optional embodiment of the present invention, Figure 1 As shown, the thickness of the silicon dioxide layer is greater than 50nm, and the bottom gate and the top gate each include a 3-5nm thick chromium layer and a 40-45nm thick gold layer from bottom to top, which does not exceed the thickness of the silicon dioxide support layer; the metal layer composition of the top gate and the bottom gate is the same. The contact resistance of the chromium-gold-metal electrode is extremely small, which reduces the parasitic capacitance in the device, and the appropriate thickness ensures the device's convergence and absorption of terahertz waves.

[0073] In another optional embodiment of the present invention, Figure 2 As shown, the bottom grid is attached to the upper surface of the silicon dioxide support layer, and the rectangular antenna parts of the bottom grid and the top grid are made of transparent semiconductor materials, preferably multilayer graphene. The materials of the wing-shaped antenna parts of the bottom grid and the top grid each include a 3-5 nm thick chromium layer and a 40-45 nm thick gold layer from bottom to top.

[0074] In the above-mentioned embodiment, the double-grid adopts a structure in which vertical discrete parts overlap and are misaligned. The degree of misalignment is a key parameter that affects the coupling of the terahertz field to the double-layer graphene. The appropriate size balances the electric field enhancement and the degree of band gap opening, that is, the overlapping area needs to be minimized to increase the output electric field of the antenna to the maximum, and the overlapping area needs to be avoided to be too small to achieve the degree of band gap opening. This electrode structure enhances the effect of terahertz field convergence and can effectively regulate the double-layer graphene. The top grid antenna and the bottom grid antenna can change their degree of misalignment, and the misalignment range is adjusted according to the actual situation. The wing-shaped antenna can be proportionally enlarged on the basis of this design, and proportionally enlarged and optimized according to the actual detected terahertz band. The rectangular antenna part is the same as the wing-shaped antenna, which ensures that it has the best effect within the detection band.

[0075] In the above-mentioned embodiment, preferably, the thickness of the wrapping layer is 15nm to 30nm; the material of the wrapping layer is boron nitride, hafnium oxide or aluminum oxide, that is, in addition to boron nitride, other wrapping materials can be selected from high-quality grown hafnium oxide or aluminum oxide, etc., wherein the use of high-quality grown hafnium oxide or aluminum oxide is because in the semiconductor process, it is necessary to consider factors such as material barriers, energy gaps, interface state density and defects, chemical and thermal stability of materials, and compatibility with standard CMOS processes; high-density and uniform high-dielectric materials are used as gate dielectrics, which can reduce the thickness of the wrapping layer without affecting the dielectric properties of the transistor (the dual-gate control graphene component part belongs to the transistor), that is, reducing the gate leakage current caused by direct electron tunneling). The function of the wrapping layer is to wrap the double-layer graphene layer to form a dual-gate control graphene, i.e., a transistor structure. At the same time, by reasonably selecting and optimizing the thickness of the dielectric layer, the parasitic capacitance in the device can be reduced, thereby achieving effective control and efficient detection of terahertz light; the carrier concentration and band gap of the double-layer graphene layer are adjustable under the action of double-gate regulation, and compared with other materials, it has strong broadband absorption.

[0076] In the above embodiments, preferably, Figure 4 As shown, the source electrode and the drain electrode are asymmetric structures; the asymmetric design of the source and drain electrodes (the destruction of their symmetry is that the gate adjustable graphene component is a pn junction, or the electrode structure extending from the source and drain electrodes is asymmetric - such as Figure 4 (15)-(16) The extended electrode structure is asymmetric), which increases the light response in the form of DC voltage between the source and drain electrodes. The source electrode and the drain electrode are close to each other but do not touch the rectangular antenna part of the bottom gate and the top gate, that is, the source and drain electrodes are as close as possible without touching the double gate. The source electrode and the drain electrode are made of chromium or gold.

[0077] The second part, such as Figure 5As shown, the present invention provides a method for preparing a double-layer graphene terahertz detector based on a vertical butterfly coupling antenna as described in any one of the above items, comprising the following steps:

[0078] S1, providing double-layer graphene and a wrapping layer material;

[0079] S2, spin coating photoresist on the silicon dioxide surface of the silicon substrate provided with a silicon dioxide support layer, exposing the photoresist according to a preset pattern of the bottom gate to obtain a pattern of the bottom gate;

[0080] Etching the bottom gate pattern without photoresist protection, depositing a metal film on the surface of the etched product, removing the metal film in the area covered by the photoresist, and obtaining a bottom gate embedded in the upper surface layer of the silicon dioxide support layer or attached to the surface of the silicon dioxide support layer;

[0081] S3, placing the double-layer graphene and the boron nitride on the rectangular antenna portion of the bottom grid in the product obtained in step S2 to form the graphene component;

[0082] S4, spin-coating a photoresist on the surface of the product obtained in step S3, exposing the photoresist according to a preset pattern of the top gate, and obtaining a pattern of the top gate;

[0083] Etching the pattern of the top gate without photoresist protection, depositing a metal film on the surface of the etched product, removing the metal film in the area covered by the photoresist, and obtaining a top gate arranged on the graphene component;

[0084] S5, modifying the shape of the graphene component in the product obtained in step S4, and removing the portion exceeding the AA' region in the length direction of the rectangular antenna;

[0085] S6, spin-coating a photoresist on the surface of the product obtained in step S5, exposing the photoresist according to a preset pattern of the source electrode and the drain electrode, and obtaining patterns of the source electrode and the drain electrode;

[0086] The source electrode and the drain electrode without photoresist protection are etched, a metal film is deposited on the surface of the etched product, and the metal film in the area covered by the photoresist is removed to obtain the source electrode and the drain electrode connected to the two ends of the graphene component.

[0087] In the above embodiment, optionally, in step S1, graphene and boron nitride are peeled off on the silicon substrate using adhesive tape to obtain double-layer graphene and boron nitride;

[0088] Preferably, if Figure 6 As shown, the material of the wrapping layer is boron nitride, and the preparation method of the graphene component comprises the following steps:

[0089] (a) spin coating a polypropylene carbonate (PPC) solution on a silicon wafer and baking to form a PPC film on the silicon wafer;

[0090] (b) The PPC film on the silicon wafer is peeled off by punching tape, and the PPC film tape is placed on the PDMS (polydimethylsiloxane) block on the transparent glass sheet to fix it, resulting in a raised structure;

[0091] (c) The protruding structure is used to first pick up the boron nitride peeled off on the silicon substrate, and then the double-layer graphene on the silicon wafer is picked up by the boron nitride, and finally the boron nitride is picked up again to form the graphene component.

[0092] According to the present invention, when the terahertz detector of the present invention is used for detection, the terahertz light spot is converged and irradiated onto the surface of the metal antenna, the antenna absorbs the terahertz wave, and the terahertz wave is converged into the graphene component through the rectangular structure, so as to realize the detection of terahertz signals at room temperature.

[0093] In order to further improve the sensitivity of the terahertz detector, in the third part, the present invention provides a method for improving the sensitivity of terahertz detection, comprising the following steps: applying an electric field to the bottom gate and the top gate of the double-layer graphene terahertz detector based on the vertical butterfly coupling antenna described in any one of the above items during the terahertz detection process, obtaining a photocurrent response and calculating the photoresponsivity; adjusting the structure of the double-layer graphene terahertz detector according to the photoresponsivity to improve the detection sensitivity at room temperature. Specifically, the detection result can be confirmed according to the responsivity and equivalent noise power of the detection device of the graphene terahertz detector at room temperature, such as the method comprising the following steps: obtaining the responsivity of the detection device at room temperature according to the maximum value of the photocurrent response and the incident light power value obtained; obtaining the equivalent noise power of the detection device at room temperature according to the responsivity and thermal noise of the detection device at room temperature; adjusting the structure of the double-layer graphene terahertz detector according to the responsivity of the detection device at room temperature to improve the detection sensitivity at room temperature. The structure of the double-layer graphene terahertz detector is adjusted to include adjusting the detector specification parameters, such as antenna size, top grid and bottom grid antenna offset overlap area, etc. For example, in one embodiment of the present invention, under the action of the double grid, the photocurrent response of the double-sided graphene terahertz detector shown in the figure clearly shows 6 distribution areas, the maximum value of the photocurrent response is selected and read out and recorded as Ipn, and according to the incident light power value Pin, according to the light loudness formula R = Ipn / Pin, the response of the detection device at room temperature is obtained to be 53.6μA / W; the equivalent noise power (NEP) is calculated based on the thermal noise, the formula Calculate k B is the Boltzmann constant, T is the working environment temperature (300K), R is the device resistance, and Rph is the light response. The NEP of this device is 46nW·Hz-1 / 2 In the present invention, the dual-grid antenna control structure can be further optimized through the V(tg) top grid and V(bg) bottom grid scanning diagrams.

[0094] In the fourth part, the present invention provides a modulation method for photoelectric detection of a terahertz detector, comprising the following steps: in the terahertz detection process, by adjusting the polarization direction of the incident light of the double-layer graphene terahertz detector based on the vertical butterfly coupling antenna described in any one of the above items, to achieve modulation of photoelectric detection at room temperature. In the above application, the modulation is manifested in adjusting the photoelectric response.

[0095] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0096] The methods used in the following examples, unless otherwise specified, are all conventional methods, carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources.

[0097] Example 1

[0098] This embodiment provides a double-layer graphene terahertz detector based on a vertical butterfly coupling antenna and a processing flow thereof.

[0099] like Figure 1 As shown, in the double-layer graphene terahertz detector based on the vertical butterfly coupling antenna of this embodiment, the bottom grid 3 is embedded in the upper surface layer of the silicon dioxide support layer 2, and the bottom grid 3 includes a 5nm thick chromium layer and a 45nm thick gold layer from bottom to top. The coating composition and thickness of the top grid 4 are the same as those of the bottom grid. The thickness of the silicon dioxide support layer 2 is 285nm, and the material of the wrapping layer 6 is boron nitride, and the thickness of the boron nitride layer is 30nm. The size of the double-layer graphene component 5 along the length direction of the rectangular antenna is 2μm. Along the length direction of the rectangular antenna, the graphene component 5 is close to but does not contact the wing-shaped antenna part of the bottom grid 3 and the top grid 4, and the size of the double-layer graphene component 5 along the length direction of the rectangular antenna is smaller than the size of the double-layer graphene component 5 along the width direction of the rectangular antenna, as shown in FIG. Figure 4 As shown, the source electrode and the drain electrode are asymmetric structures (the electrode structure extending from the source and drain electrodes is asymmetric).

[0100] The method for preparing a double-layer graphene terahertz detector based on a vertical butterfly coupling antenna in this embodiment includes:

[0101] (1) Use scotch tape to peel off graphene on a silicon substrate, look for double-layer graphene under an optical microscope, and finally characterize the double-layer graphene by Raman spectroscopy (see Figure 7 for the Raman spectrum). Use the same method to peel off 30nm of boron nitride (hBN).

[0102] (2) Micro-nano processing, the specific steps are as follows:

[0103] 1) First, a bottom-gate antenna structure is prepared, photoresist is spin-coated on a silicon dioxide surface of a silicon substrate with a gold mark and a silicon dioxide support layer, and the photoresist is exposed using an EBL process according to a preset pattern of the bottom gate to obtain a bottom-gate pattern;

[0104] The bottom gate pattern (SiO2) without photoresist protection is etched using RIE (plasma etching) process, with a thickness of about 50nm. A 5nm chromium film and a 45nm gold film are sequentially deposited on the surface of the etched product by electron beam evaporation method. The metal film in the area covered by the photoresist is stripped in acetone solution to obtain the bottom gate embedded in the silicon dioxide support layer.

[0105] 2) Placing double-layer graphene and boron nitride on the rectangular antenna portion of the bottom grid in the product obtained in step 1) to form a graphene component (hBN / BLG / hBN stacking), the specific steps are as follows:

[0106] (a) PPC (poly(methyl ethylene carbonate)) was used for lamination. The PPC film was prepared by spin coating a PPC solution dissolved in anisole on a silicon wafer and baking it on a hot plate at 90 degrees for 2 minutes.

[0107] (b) The PPC film on the silicon wafer is peeled off with a perforated tape and placed on a 1mm*1mm PDMS (polydimethylsiloxane) square on a transparent glass sheet. The resulting raised structure is used to pick up two-dimensional materials.

[0108] (c) The structure is used to first pick up the thin layer of hBN (boron nitride) peeled off on the silicon substrate, then pick up the double-layer graphene on the silicon wafer through the hBN, and finally pick up the hBN again to form an hBN-BLG-hBN sandwich structure.

[0109] (d) The stacked hBN-BLG-hBN structure is accurately placed on the rectangular lead of the bottom grid-antenna, and then the top layer-antenna structure is processed.

[0110] 3) Spin-coating a photoresist on the surface of the product obtained in step 2), and exposing the photoresist using an EBL process according to a preset pattern of the top gate to obtain a pattern of the top gate;

[0111] The top gate pattern without photoresist protection is etched using RIE process, and 50nm of Au is evaporated on the surface of the etched product; the metal film in the photoresist-covered area is peeled off in acetone solution to obtain the top gate set on the graphene component (note that the rectangular legs of the top gate antenna and the bottom gate antenna do not completely overlap in this process, and need to be half-displaced and half-overlapped);

[0112] 4) using RIE process (plasma etching) to modify the shape of the graphene component in the product obtained in step 3), removing the part that exceeds the length direction of the rectangular antenna, and processing to obtain a long strip BLG that does not exceed the electrode area in the longitudinal direction (the long side direction of the rectangular electrode);

[0113] 5) Further use laser direct writing to obtain the source and drain electrodes of the device. The specific operations are as follows:

[0114] Spin-coating a photoresist on the surface of the product obtained in step 4), exposing the photoresist according to a preset pattern of the source electrode and the drain electrode, and obtaining a pattern of the source electrode and the drain electrode;

[0115] The RIE process is used to etch the patterns of the source electrode and drain electrode without photoresist protection to expose the hBN-wrapped graphene layer. A gold electrode with a thickness greater than the etching depth is evaporated on the surface of the etched product. The product is placed in an acetone solution to remove the gold film in the area covered with the photoresist, thereby obtaining the source electrode and drain electrode connected at both ends of the graphene component.

[0116] The optical photographs of the double-layer graphene terahertz detector based on the vertical butterfly coupling antenna prepared in this embodiment during the processing are shown in the figure. Figure 8 As shown in the figure, the actual photo of the detector under the 100x objective lens is as follows Fig. 9 shown.

[0117] Example 2

[0118] This embodiment is used to discuss the process of realizing room temperature and high sensitivity detection of terahertz waves by controlling the doping concentration of the BLG pn junction.

[0119] (1) Electrical testing

[0120] Electrical tests were performed on the double-layer graphene terahertz detector based on the vertical butterfly-shaped coupling antenna prepared in Example 1. The butterfly antenna acts as the top gate and bottom gate of the device to regulate the carrier distribution in the graphene channel region, thereby constructing a pn junction and improving the sensitivity of terahertz detection. The measurement was performed at room temperature. The same gate voltage V(tg)=V(bg) was applied to the double gates of the device to obtain the change of the channel resistance R with the graphene carrier concentration n, as shown in FIG. Fig.10 As shown in (a), the mobility of electrons and holes at room temperature is calculated and fitted. They are 15000 and 11000 cm 2 / V·s, the contact resistance of the device RC = 522±2Ω, and the residual carrier concentration n = 4.6×10 11 cm -2 , the parasitic capacitance including contact resistance in the device is reduced, which can improve the detection sensitivity of the device. Fig.10 (b) It can be seen that there is a large oblique line with a large resistance value in the pn and np regions, which is due to the influence of the gate overlap area on the device resistance. The resistance change of this oblique line is small, so the band gap opened by the device at room temperature is extremely small, which limits the reduction of the dark current noise I(dark) in the device and reduces the effect of improving the responsiveness of the terahertz detection device. Therefore, the dual-gate antenna control structure needs to be further optimized (such as increasing the dual-gate overlap area, selecting a dielectric material with a higher dielectric constant, etc.) to achieve a larger band gap at room temperature.

[0121] It can be seen from the above results that the present invention can further regulate the doping concentration on both sides of the junction region by applying an electric field at both ends of the bottom gate and top gate antennas of the terahertz detector device, thereby further improving the sensitivity of terahertz detection, so as to achieve a wide range of regulation of the band gap of double-layer graphene and realize terahertz detection based on the photovoltaic effect or photothermoelectric (PTE) effect in graphene at room temperature.

[0122] (2) Terahertz characteristics

[0123] At room temperature, the device measurement results in the terahertz band (2.7 Thz) are as follows Fig.11 As shown: Under dual-gate regulation, the photocurrent response of the BLG detector clearly shows 6 regions, such as Fig.11 (a) shows that the detection mechanism of the BLG detector is still the photothermoelectric effect. However, in the pn and np regions, which are the expected band gap opening regions, the photocurrent is about 0.4nA at room temperature, indicating that the band gap opened by the device at room temperature is very small. After calculation, its responsivity is 53.6μA / W and NEP is 46nW·Hz -1 / 2 . Fig.11 (b) is the function of photocurrent and incident power, P diff is the effective power value irradiated on the device. The test results of the device at the optimal working point show a linear relationship, indicating that the photocurrent is proportional to the incident power. The working mode of this device is mainly based on the photothermoelectric effect.

[0124] In addition, the device has polarization characteristics, according to Fig.12 It can be seen that I ph||(0°) / I ph⊥(90°)=0.5nA / 0.12nA≈5, this device has different responses to light with different polarization directions. Its radiation pattern also shows the polarization characteristics of a dipole antenna, that is, when the polarization direction of the incident light is parallel to the long axis of the device, the photocurrent reaches its maximum value, and when the polarization direction of the incident light is perpendicular to the long axis of the device, the photocurrent reaches its minimum value. It is worth noting that the radiation pattern has small peaks of lower intensity at 90° and 270°, which may be caused by the leads that contact the antenna with the channel. This result shows that the photoelectric response of the device is related to its geometry and structure, and modulation of photoelectric detection can be achieved by adjusting the polarization direction.

[0125] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, can implement the present invention in a wider range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that the present invention can be further improved. In a word, according to the principle of the present invention, the application is intended to include any changes, uses or improvements to the present invention, including departing from the disclosed scope in the application and the changes made with conventional techniques known in the art.

Claims

1. A double-layer graphene terahertz detector based on a vertical butterfly-shaped coupling antenna, characterized in that: include: Silicon substrate; A silicon dioxide support layer attached to the upper surface of the silicon substrate; A bottom grid embedded in the upper surface of the silicon dioxide support layer or attached to the upper surface of the silicon dioxide support layer includes a wing-shaped antenna portion and a rectangular antenna portion extending from the root of the wing-shaped antenna; A top gate arranged in parallel above the silicon dioxide support layer comprises a fin-shaped antenna portion and a rectangular antenna portion extending from the root of the fin-shaped antenna; The bottom grid and the top grid together form a bow-tie structure in the horizontal direction, wherein the rectangular antenna portion of the bottom grid and the rectangular antenna portion of the top grid are parallel along the length direction of the rectangular antenna and half-staggered and half-overlapped along the width direction of the rectangular antenna; A graphene component, which connects the rectangular antenna part of the bottom grid and the rectangular antenna part of the top grid from top to bottom, comprises a wrapping layer, a double-layer graphene layer and a wrapping layer of a sandwich structure from bottom to top, and the size of the graphene component along the length direction of the rectangular antenna does not exceed the rectangular antenna parts of the bottom grid and the top grid; A source electrode and a drain electrode are respectively connected to the left and right ends of the graphene component.

2. The double-layer graphene terahertz detector based on vertical butterfly coupling antenna according to claim 1, characterized in that: Along the length direction of the rectangular antenna, the graphene component is close to but not in contact with the fin-shaped antenna parts of the bottom grid and the top grid; A dimension of the double-layer graphene component along a length direction of the rectangular antenna is smaller than a dimension of the double-layer graphene component along a width direction of the rectangular antenna.

3. The double-layer graphene terahertz detector based on a vertical butterfly-shaped coupling antenna according to any one of claims 1 to 2, characterized in that: The bottom gate is embedded in the upper surface layer of the silicon dioxide support layer, the thickness of the silicon dioxide layer is greater than 50nm, and the bottom gate and the top gate each include a 3-5nm thick chromium layer and a 40-45nm thick gold layer from bottom to top.

4. The double-layer graphene terahertz detector based on a vertical butterfly-shaped coupling antenna according to any one of claims 1 to 2, characterized in that: The bottom grid is attached to the upper surface of the silicon dioxide support layer, and the rectangular antenna parts of the bottom grid and the top grid are both made of transparent semiconductor materials, preferably multilayer graphene.

5. The double-layer graphene terahertz detector based on a vertical butterfly-shaped coupling antenna according to any one of claims 1 to 4, characterized in that: The thickness of the encapsulation layer is 15nm to 30nm; The material of the wrapping layer is boron nitride, hafnium oxide or aluminum oxide.

6. The double-layer graphene terahertz detector based on a vertical butterfly-shaped coupling antenna according to any one of claims 1 to 5, characterized in that: The source electrode and the drain electrode are of asymmetric structure; The source electrode and the drain electrode are close to each other but do not contact the rectangular antenna portion of the bottom gate and the top gate; The source electrode and the drain electrode are made of gold or chromium.

7. The method for preparing a double-layer graphene terahertz detector based on a vertical butterfly coupling antenna according to any one of claims 1 to 6 comprises the following steps: S1, providing double-layer graphene and a wrapping layer material; S2, spin coating photoresist on the silicon dioxide surface of the silicon substrate provided with a silicon dioxide support layer, exposing the photoresist according to a preset pattern of the bottom gate to obtain a pattern of the bottom gate; Etching the bottom gate pattern without photoresist protection, depositing a metal film on the surface of the etched product, removing the metal film in the area covered by the photoresist, and obtaining a bottom gate embedded in the upper surface layer of the silicon dioxide support layer or attached to the surface of the silicon dioxide support layer; S3, placing the double-layer graphene and the wrapping layer material on the rectangular antenna portion of the bottom grid in the product obtained in step S2 to form the graphene component; S4, spin-coating a photoresist on the surface of the product obtained in step S3, exposing the photoresist according to a preset pattern of the top gate, and obtaining a pattern of the top gate; Etching the pattern of the top gate without photoresist protection, depositing a metal film on the surface of the etched product, removing the metal film in the area covered by the photoresist, and obtaining a top gate arranged on the graphene component; S5, modifying the shape of the graphene component in the product obtained in step S4, and removing the portion that exceeds the length direction of the rectangular antenna; S6, spin-coating a photoresist on the surface of the product obtained in step S5, exposing the photoresist according to a preset pattern of the source electrode and the drain electrode, and obtaining patterns of the source electrode and the drain electrode; The source electrode and the drain electrode without photoresist protection are etched, a metal film is deposited on the surface of the etched product, and the metal film in the area covered by the photoresist is removed to obtain the source electrode and the drain electrode connected to the two ends of the graphene component.

8. The method for preparing a double-layer graphene terahertz detector based on a vertical butterfly coupling antenna according to claim 7, characterized in that: When the material of the wrapping layer is boron nitride, the method for preparing the graphene component comprises the following steps: (a) spin coating a polypropylene carbonate solution on a silicon wafer and baking to form a PPC film on the silicon wafer; (b) peeling off the PPC film on the silicon wafer by means of a perforated tape, and placing the PPC film tape on a polydimethylsiloxane block on a transparent glass sheet to fix it, thereby obtaining a protruding structure; (c) The protruding structure is used to first pick up the boron nitride peeled off on the silicon substrate, then pick up the double-layer graphene on the silicon wafer through the boron nitride, and finally pick up the boron nitride again to form the graphene component.

9. A method for improving terahertz detection sensitivity, characterized in that: The steps include: In the terahertz detection process, an electric field is applied to the bottom gate and the top gate of the double-layer graphene terahertz detector based on the vertical butterfly coupling antenna according to any one of claims 1 to 6, respectively, to obtain a photocurrent response and calculate the photoresponsivity; According to the light response, the structure of the double-layer graphene terahertz detector is adjusted to improve the detection sensitivity at room temperature.

10. A modulation method for photoelectric detection of a terahertz detector, characterized in that: The steps include: In the terahertz detection process, the polarization direction of the incident light of the double-layer graphene terahertz detector based on the vertical butterfly coupling antenna according to any one of claims 1 to 6 is adjusted to achieve modulation of photoelectric detection at room temperature.

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