CN120264870A - A graphene flexible terahertz wave detector and preparation method thereof - Google Patents
A graphene flexible terahertz wave detector and preparation method thereof Download PDFInfo
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Abstract
本发明公开了一种石墨烯柔性太赫兹波探测器及其制备方法，所述探测器包括衬底层和石墨烯层；所述衬底层为柔性绝缘结构，所述石墨烯层位于所述衬底层的上方，所述石墨烯层为单层石墨烯薄膜，所述石墨烯层两端分别覆盖连接有非对称电极的源极金属电极和漏极金属电极。本申请提供的石墨烯柔性太赫兹波探测器，具有良好的柔韧性和稳定性，支持可识别、可重复的太赫兹响应，并可将响应波长范围拓展至紫外至毫米波频段。在与柔性曲面共形附着下，实现对复合材质物体和隐匿物体的高分辨率太赫兹波成像。
The present invention discloses a graphene flexible terahertz wave detector and a preparation method thereof, wherein the detector comprises a substrate layer and a graphene layer; the substrate layer is a flexible insulating structure, the graphene layer is located above the substrate layer, the graphene layer is a single-layer graphene film, and the two ends of the graphene layer are respectively covered with a source metal electrode and a drain metal electrode connected to an asymmetric electrode. The graphene flexible terahertz wave detector provided in the present application has good flexibility and stability, supports recognizable and repeatable terahertz response, and can expand the response wavelength range to ultraviolet to millimeter wave frequency bands. Under conformal attachment to a flexible curved surface, high-resolution terahertz wave imaging of composite material objects and hidden objects is achieved.
Description
Technical Field
The invention relates to the technical field of flexible wearable terahertz wave detection and imaging, in particular to a graphene flexible terahertz wave detector and a preparation method thereof.
Background
Terahertz waves (0.1 THz-10 THz) are used as transition wave bands between microwaves and infrared rays in electromagnetic spectrums, have the characteristics of low photon energy, high penetrability, high bandwidth, molecular fingerprint spectrum and the like, and have important application prospects in the fields of wireless communication, radar imaging, medical detection and the like. The terahertz detector is used as a core functional component of a terahertz technology system, and can realize target object detection and two-dimensional image reconstruction by converting terahertz wave signals into electric signals. The miniaturized and flexible terahertz wave detector can improve the integration level, resolution and applicability of devices, and provides a technical basis for developing a high-spatial-resolution wearable imaging system. However, commercial terahertz detectors (such as Gao Laiguan, bolometers, schottky diodes, etc.) still face core challenges in terms of miniaturization, high-resolution detection and imaging, and conventional materials are bulky and limited in detection efficiency due to low terahertz absorption efficiency, need to rely on antennas to achieve terahertz focusing. In addition, most practical objects have three-dimensional curvature, which cannot be accurately measured by conventional rigid terahertz detectors. For example, in the current technology, terahertz images for human body safety inspection are obtained by rotating a terahertz detector by 360 °, which results in a terahertz imaging system that is very heavy. Although several types of terahertz tomography techniques have been reported, they still require complex systems and cannot be moved, which is disadvantageous for miniaturization and high integration of the detection and imaging systems.
Therefore, how to design a flexible terahertz wave detector to improve the integration level, the curved surface imaging capability and the application range of the terahertz wave detection and imaging system has become a technical problem to be solved by those skilled in the art.
Disclosure of Invention
The invention provides a graphene flexible terahertz wave detector and a preparation method thereof, which are used for solving the technical problems of how to design the flexible terahertz wave detector so as to improve the integration level and the application range of a terahertz wave detection and imaging system and improve the detection efficiency and the curved surface imaging capability of the terahertz wave detector.
The invention provides a graphene flexible terahertz wave detector which comprises a substrate layer and a graphene layer, wherein the substrate layer is of a flexible insulation structure, the graphene layer is positioned above the substrate layer, the graphene layer is a single-layer graphene film, and two ends of the graphene layer are respectively covered with a source electrode metal electrode and a drain electrode metal electrode which are connected with asymmetric electrodes.
According to the technical scheme, the graphene flexible terahertz wave detector comprises a substrate layer with a flexible insulating structure, a single-layer graphene layer, a source electrode metal electrode and a drain electrode metal electrode, has good flexibility and stability, and supports identifiable and repeatable terahertz response. The source metal electrode and the drain metal electrode are formed by asymmetric electrodes, have a wide-spectrum photo-thermal electric effect from ultraviolet to millimeter wave frequency bands, and the single-layer graphene layer has wide-spectrum absorption from ultraviolet to millimeter wave frequency bands, so that the response wavelength range can be expanded to ultraviolet to millimeter wave frequency bands. Because the substrate layer is of a flexible insulating structure, the graphene flexible terahertz wave detector can realize high-resolution terahertz wave imaging of composite material objects and hidden objects under conformal attachment with a flexible curved surface.
Further, the graphene layer is of a rectangular structure.
Further, the rectangular structure has a long dimension ranging from 2 μm to 3000 μm, and the rectangular structure has a wide dimension ranging from 2 μm to 3000 μm.
Further, the source metal electrode and/or the drain metal electrode is circular.
Further, the diameter of the circle ranges from 10 μm to 1000 μm.
Further, the source metal electrode and/or the drain metal electrode is regular polygon.
Further, the side length of the regular polygon ranges from 10 mu m to 1000 mu m.
Further, the source metal electrode is any one of Al, ag, au, bi, cr, ti, ni and the drain metal electrode is any one of Al, ag, au, bi, cr, ti, ni, and the source metal electrode and the drain metal electrode are different in material.
Further, the substrate layer is made of a single material selected from any one of mica, polyethylene terephthalate, polydimethylsiloxane, polymethyl methacrylate, polystyrene and polyvinyl alcohol.
The invention further provides a preparation method of the graphene flexible terahertz wave detector, which comprises the following steps:
Performing plasma etching treatment on one surface of the obtained substrate layer to form a hydrophilic surface;
transferring a graphene layer on one surface of the substrate layer subjected to hydrophilic treatment, and performing patterning treatment on the graphene layer to obtain a single-layer graphene film;
and carrying out photoetching, sputtering, deposition or evaporation treatment on two ends of the graphene layer to form a source electrode metal electrode and a drain electrode metal electrode of an asymmetric electrode so as to obtain the graphene flexible terahertz wave detector.
The application provides a graphene flexible terahertz wave detector and a preparation method thereof, and compared with the prior art, the graphene flexible terahertz wave detector has the following beneficial effects:
According to the graphene flexible terahertz wave detector, the source metal electrode and the drain metal electrode are formed by asymmetric electrodes, the graphene flexible terahertz wave detector has a wide-spectrum photo-thermal effect from ultraviolet to millimeter wave frequency bands, the single-layer graphene layer has wide-spectrum absorption from ultraviolet to millimeter wave frequency bands, and the response wavelength range can be expanded to ultraviolet to millimeter wave frequency bands. Because the substrate layer is of a flexible insulating structure, the graphene flexible terahertz wave detector can realize high-resolution terahertz wave imaging of composite material objects and hidden objects under conformal attachment with a flexible curved surface.
Drawings
Fig. 1 is a schematic diagram of a front view structure of a graphene flexible terahertz wave detector provided in embodiment 1 of the present invention;
Fig. 2 is a schematic top view structure of a graphene flexible terahertz wave detector provided in embodiment 1 of the present invention;
fig. 3 is a schematic diagram of the optical response of the graphene flexible terahertz wave detector in embodiment 1 of the present invention under the irradiation of 2.52THz laser at different laser powers;
Fig. 4 is a schematic diagram of the optical response of the graphene flexible terahertz wave detector in embodiment 1 under the irradiation of laser with different wavelengths in the ultraviolet to millimeter wave frequency band;
Fig. 5 is a schematic diagram of the optical response of the graphene flexible terahertz wave detector in embodiment 2 of the present invention under the irradiation of 2.52THz laser at different laser powers;
fig. 6 is a schematic diagram of the optical response of the graphene flexible terahertz wave detector in embodiment 3 of the present invention under the irradiation of 2.52THz laser at different laser powers;
Fig. 7 is a schematic diagram of the optical response of the graphene flexible terahertz wave detector in embodiment 4 under the irradiation of 2.52THz laser at different laser powers;
FIG. 8 is a schematic diagram of the photo-response of the graphene flexible terahertz wave detector under the irradiation of 2.52THz laser at different bending angles;
FIG. 9 is a schematic diagram of the photo-response of the graphene flexible terahertz wave detector under different bending times under the conditions of 2.52THz laser irradiation and 60-degree bending angle;
FIG. 10 is a schematic diagram of a graphene flexible terahertz wave detector of the present invention conformally attached to a curved surface;
FIG. 11 is a schematic view of terahertz wave imaging of a composite object when the graphene flexible terahertz wave detector is conformally attached to a curved surface under 2.52THz laser irradiation;
fig. 12 is a flowchart of a method for manufacturing the graphene flexible terahertz wave detector of the present invention.
Reference numerals:
1-source metal electrode, 2-graphene layer, 3-drain metal electrode, 4-substrate layer.
Detailed Description
The following examples are given for illustrative purposes only and are not to be construed as limiting the invention, as embodiments of the invention are specifically illustrated by the accompanying drawings, which are included by reference and description only, and do not limit the scope of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. In the description of the present invention, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", "a third", etc. may explicitly or implicitly include one or more such feature. In the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.
In the description of the present invention, unless explicitly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected, mechanically connected, electrically connected, directly connected, indirectly connected via an intervening medium, or in communication between two elements. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and the like are used herein for descriptive purposes only and not to indicate or imply that the apparatus or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In the description of the present invention, it should be noted that all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art unless defined otherwise. The terminology used in the description of the present invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention, as the particular meaning of the terms described above in the present invention will be understood to those of ordinary skill in the art in the detailed description of the invention.
Van der Waals two-dimensional atomic crystals refer to materials in which electrons can move freely (planar motion) only in two dimensions, non-nanoscale (1-100 nm), have unique interlayer weak interactions, controllable electron band structures and mechanical stretching characteristics, and are considered as potential flexible detector materials. It has been reported that two-dimensional semiconductors such as transition metal sulfides (TMDC) and black phosphorus are used to fabricate two-terminal devices of simple structure on flexible substrates, which have excellent responsivity, specific detection rate and response time, up to the order of 1.28x 3A/W、3.02 × 1011 Jones and milliseconds, respectively. However, two-dimensional semiconductors have a relatively wide band gap, making them operable only in the ultraviolet to near infrared bands. In contrast, two-dimensional semi-metals (such as graphene, WTe 2、PtTe2、PdTe2、NiTe2 and T d-MoTe2) have zero bandgap structures, and in particular, the second type of semi-metals (such as WTe 2、Cd3As2 and T d-MoTe2) have inclined linear electron dispersion relationships, and exhibit rapid photoelectric response in a wide spectral range from ultraviolet to terahertz wave bands under the drive of photoexcitation hot carriers. However, most of the reported two-dimensional half-metal photodetectors are fabricated on rigid substrates, and even on flexible substrates, additional antenna integration or longer channels are required to achieve long-wave detection, resulting in large device area, slow response speed, and complex fabrication, limiting the detection and imaging applications of the detectors in miniaturized, flexible, and wearable devices.
The photo-thermal effect is a physical phenomenon that under the induction of light, temperature difference is formed at two ends of a material to promote the diffusion of carriers so as to generate photocurrent, and is a representative photoelectric response mechanism in a graphene photoelectric detector. Because the energy of the terahertz wave is 0.414meV-41.4meV, which is far smaller than the energy of the interband transition of the graphene carriers (the energy of the interband transition is 2E f), incident light mainly excites hot carriers in the graphene layer through the inband, so that the carrier temperature in single-layer graphene is improved, and the metal electrodes of the asymmetric electrodes at the two ends act as radiating fins, so that the temperature distribution along the channel is uneven. Meanwhile, the work function difference of the asymmetric electrode metals at the two ends can cause metal induced doping of different degrees at the two ends of the graphene, so that non-uniform local fermi level distribution is generated in a channel region. The asymmetric fermi level and temperature profile further results in a position dependent seebeck coefficient profile, the presence of which induces a local potential gradient, thereby facilitating the diffusion of hot carriers and hence photocurrent response. Therefore, the single-layer graphene and the asymmetric electrode metal electrode are introduced on the flexible substrate, so that the efficient detection of ultraviolet to millimeter wave frequency bands including terahertz waves is hopeful to be realized, the detection area of the device is reduced, and the miniaturization and the improvement of the integration level of the flexible electronic device are facilitated.
In view of this, as shown in fig. 1 and 2, in embodiment 1 of the present invention, a graphene flexible terahertz wave detector includes a substrate layer 4 and a graphene layer 2, wherein the substrate layer 4 is of a flexible insulating structure, the graphene layer 2 is located above the substrate layer 4, the graphene layer 2 is a single-layer graphene film, and two ends of the graphene layer 2 are respectively covered with a source metal electrode 1 and a drain metal electrode 3 connected with asymmetric electrodes. It should be noted that the "source metal electrode 1 and the drain metal electrode 3 of the asymmetric electrode" means that the source metal electrode 1 and the drain metal electrode 3 are made of metals of two different materials.
In this embodiment, the graphene flexible terahertz wave detector includes a substrate layer 4 of a flexible insulating structure, a single-layer graphene layer 2, a source metal electrode 1 and a drain metal electrode 3, has good flexibility and stability, and supports identifiable and repeatable terahertz response. Because the source metal electrode 1 and the drain metal electrode 3 are asymmetric electrodes and have different work functions, the carrier concentration of the contact areas of the graphene layer 2, the source metal electrode 1 and the drain metal electrode 3 is different, hot carrier diffusion is promoted, and the detection performance of the graphene flexible terahertz wave detector can be effectively improved.
In this embodiment, the substrate layer 4 is polyethylene terephthalate (Polythylene terephthalate, PET), the source metal electrode 1 and the drain metal electrode 3 are Ti and Bi, respectively, the source metal electrode 1 and the drain metal electrode 3 have a wide spectrum photo-thermal effect from ultraviolet to millimeter wave, the single-layer graphene layer 2 has a wide spectrum absorption from ultraviolet to millimeter wave, and the response wavelength range can be expanded to ultraviolet to millimeter wave. Because the substrate layer 4 is of a flexible insulating structure, the graphene flexible terahertz wave detector can realize high-resolution terahertz wave imaging of composite material objects and hidden objects under conformal attachment with a flexible curved surface.
In the embodiment of the application, in the terahertz wave detection process of the graphene flexible terahertz wave detector, the bias voltage V ds =0 is kept, the terahertz wave irradiates on the graphene layer 2, and a current signal or a voltage signal is obtained at the source metal electrode 1 and the drain metal electrode 3. The source metal electrode 1 and the drain metal electrode 3 are asymmetric due to metal materials, and the work function difference of the asymmetric electrode metals at the two ends can cause metal induced doping at the two ends of the graphene to different degrees, so that non-uniform local fermi energy distribution is generated in a channel region of the graphene layer 2, and a temperature gradient exists at the two sides, so that a photo-thermal-electric effect is generated. By changing parameters such as the size of a graphene channel, the materials of the source electrode metal electrode 1 and the drain electrode metal electrode 3 and the like, identifiable and stable room-temperature terahertz wave detection is realized. Fig. 3 is a schematic diagram showing the photo-response of the graphene flexible terahertz wave detector based on the PET substrate under the irradiation of 2.52THz laser, and the photocurrent increases linearly with the increase of the power.
In the preferred embodiment of the application, the response wavelength range of the graphene flexible detector can be expanded to the ultraviolet to millimeter wave frequency band due to the wide-spectrum photo-thermal-electric effect of the asymmetric electrode in the ultraviolet to millimeter wave frequency band. As shown in fig. 4, the magnitude of the optical response of the graphene flexible terahertz wave detector under the irradiation of lasers with different wavelengths in the ultraviolet-millimeter wave frequency range is shown, the optical response shows an obvious response in the ultraviolet-millimeter wave frequency range along with the change of the excitation wavelength, and the optical response gradually increases along with the increase of the excitation wavelength, which indicates that the graphene flexible terahertz wave detector has a broad-spectrum response covering the terahertz wave from the ultraviolet-millimeter wave frequency range and is the widest response spectrum in the currently reported flexible two-dimensional detector.
Wherein the graphene layer 2 has a rectangular structure.
In addition, the rectangular structure has a long dimension ranging from 2 μm to 3000 μm, and a wide dimension ranging from 2 μm to 3000 μm.
Wherein the source metal electrode 1 and/or the drain metal electrode 3 are circular. Because the source electrode metal electrode 1 and/or the drain electrode metal electrode 3 are circular, sampling the symmetrical structure can enhance the local electric field and improve the graphene absorption, thereby enhancing the device response. The thicknesses of the source metal electrode 1 and the drain metal electrode 3 are larger than the thickness of the graphene layer 2.
In addition, the diameter of the circle is 10 μm to 1000 μm.
Wherein the source metal electrode 1 and/or the drain metal electrode 3 are regular polygons. Because the source electrode metal electrode 1 and/or the drain electrode metal electrode 3 are regular polygons, sampling the symmetrical structure can enhance the local electric field and improve the graphene absorption, thereby enhancing the response of the device
In addition, the side length of the regular polygon ranges from 10 μm to 1000 μm.
Example 2
Unlike example 1, the substrate layer 4 is Polydimethylsiloxane (PDMS), the graphene layer 2 is a single-layer graphene film, and both ends of the graphene layer 2 are respectively covered with the source metal electrode 1 and the drain metal electrode 3 connected with the asymmetric electrode, above the substrate layer 4. The source metal electrode 1 and the drain metal electrode 3 are Ti and Bi, respectively.
In the embodiment of the application, in the terahertz wave detection process of the graphene flexible terahertz wave detector, the bias voltage V ds =0 is kept, the terahertz wave irradiates on the graphene layer 2, and a current signal or a voltage signal is obtained at the source metal electrode 1 and the drain metal electrode 3. The source metal electrode 1 and the drain metal electrode 3 are asymmetric due to metal materials, and the work function difference of the asymmetric electrode metals at the two ends can cause metal induced doping at the two ends of the graphene to different degrees, so that non-uniform local fermi energy distribution is generated in a channel region of the graphene layer 2, and a temperature gradient exists at the two sides, so that a photo-thermal-electric effect is generated. The photo-thermal electric effect drives the hot carrier to move in the channel, so that identifiable and stable room-temperature terahertz wave detection is realized. As shown in fig. 5, the photo-response of the graphene flexible terahertz wave detector based on the PDMS substrate under the irradiation of 2.52THz laser is shown in a schematic diagram, and the photocurrent increases linearly with the increase of the power.
Example 3
The difference from embodiment 1 is that the source metal electrode 1 and the drain metal electrode 3 are composed of Ti and Cr, respectively. The substrate layer 4 is polyethylene terephthalate (Polythylene terephthalate, PET), the graphene layer 2 is positioned above the substrate layer 4, the graphene layer 2 is a single-layer graphene film, and two ends of the graphene layer 2 are respectively covered with a source metal electrode 1 and a drain metal electrode 3 which are connected with asymmetric electrodes.
In the embodiment of the application, in the terahertz wave detection process of the graphene flexible terahertz wave detector, the bias voltage V ds =0 is kept, the terahertz wave irradiates on the graphene layer 2, and a current signal or a voltage signal is obtained at the source metal electrode 1 and the drain metal electrode 3. The source metal electrode 1 and the drain metal electrode 3 are asymmetric due to metal materials, and the work function difference of the asymmetric electrode metals at the two ends can cause metal induced doping at the two ends of the graphene to different degrees, so that non-uniform local fermi energy distribution is generated in a channel region of the graphene layer 2, and a temperature gradient exists at the two sides, so that a photo-thermal-electric effect is generated. The photo-thermal electric effect drives the hot carrier to move in the channel, so that identifiable and stable room-temperature terahertz wave detection is realized. As shown in fig. 6, the graphene flexible terahertz wave detector based on the Ti and Cr asymmetric electrodes is shown as a schematic diagram of the photo-response of the graphene flexible terahertz wave detector under the irradiation of 2.52THz laser at different excitation powers, and the photocurrent increases linearly with the increase of the power.
Example 4
The difference from embodiment 2 is that the source metal electrode 1 and the drain metal electrode 3 are composed of Ti and Cr, respectively. The substrate layer 4 is Polydimethylsiloxane (PDMS), the graphene layer 2 is located above the substrate layer 4, the graphene layer 2 is a single-layer graphene film, and two ends of the graphene layer 2 are respectively covered with a source metal electrode 1 and a drain metal electrode 3 connected with asymmetric electrodes.
In the embodiment of the application, in the terahertz wave detection process of the graphene flexible terahertz wave detector, the bias voltage V ds =0 is kept, the terahertz wave irradiates on the graphene layer 2, and a current signal or a voltage signal is obtained at the source metal electrode 1 and the drain metal electrode 3. The source metal electrode 1 and the drain metal electrode 3 are asymmetric due to metal materials, and the work function difference of the asymmetric electrode metals at the two ends can cause metal induced doping at the two ends of the graphene to different degrees, so that non-uniform local fermi energy distribution is generated in a channel region of the graphene layer 2, and a temperature gradient exists at the two sides, so that a photo-thermal-electric effect is generated. The photo-thermal electric effect drives the hot carrier to move in the channel, so that identifiable and stable room-temperature terahertz wave detection is realized. As shown in fig. 7, the photo-response of the graphene flexible terahertz wave detector based on the PDMS substrate and the Ti and Cr asymmetric electrodes under the irradiation of 2.52THz laser is shown, and the photocurrent increases linearly with the increase of the power.
In the above embodiments 1 to 4, the substrate layer 4 may be made of a single material selected from mica, polyethylene terephthalate, polydimethylsiloxane, polymethyl methacrylate, polystyrene, and polyvinyl alcohol. When the material of the substrate layer 4 is unchanged, the source metal electrode 1 is any one of Al, ag, au, bi, cr, ti, ni, the drain metal electrode 3 is any one of Al, ag, au, bi, cr, ti, ni, and the source metal electrode 1 and the drain metal electrode 3 are different in material. The graphene flexible terahertz wave detector is subjected to 2.52THz laser irradiation, and the photocurrent is linearly increased along with the increase of power, and can fluctuate within the range of 0.2nA to 10nA under the condition that the source electrode metal electrode 1 and the drain electrode metal electrode 3 are made of different materials. The source metal electrode 1 and the drain metal electrode 3 are made of the same material and have no influence on the photoelectric current.
The substrate layer 4 is made of a single material selected from one of mica, polymethyl methacrylate, polystyrene, and polyvinyl alcohol, and the source metal electrode 1 and the drain metal electrode 3 are made of two different materials selected from one of Al, ag, au, bi, cr, ti, ni. The thickness of the substrate layer 4 is 80 μm to 500 μm. The substrate layer 4 and the graphene layer 2 have good mechanical flexibility, and can have excellent flexibility and repeatable terahertz wave response under different bending angles and bending times. As shown in fig. 8, the photo-response of the graphene flexible terahertz wave detector under 2.52THz laser irradiation at different bending angles is schematically shown, and the photocurrent intensity is slightly reduced (8%) along with the increase of the bending angle, which is presumably caused by the reduction of the plasmon resonance intensity due to the deformation of the graphene rectangular patterned structure array. As shown in fig. 9, the photo-response of the graphene flexible terahertz wave detector is shown in a schematic diagram under the conditions of 2.52THz laser irradiation and 60-degree bending angle and different bending times, after bending is repeated for 100 times, the photocurrent only decays by 0.3%, which indicates that the device can further bend for a plurality of times. The slight fluctuation in photocurrent intensity during bending may be caused by a slight change in the laser irradiation position. The result shows that the device has good flexibility and stable photocurrent, is suitable for terahertz wave detection and imaging when a three-dimensional curved surface is conformally attached, and has important application potential in wearable intelligent electronic equipment.
Fig. 10 is a schematic diagram showing conformal adhesion of a graphene flexible terahertz wave detector to a curved surface, where the graphene flexible terahertz wave detector can perform non-invasive imaging on an object in a curved state. The device is fixed on the curved surface of the wrist of a human body, and the terahertz wave imaging capability of the device on a composite material object and a hidden object is researched by using a terahertz bifocal imaging system. Fig. 11 shows a schematic view of terahertz wave imaging of a composite material object when a graphene flexible terahertz wave detector is attached to a curved surface in a conformal manner under 2.52THz laser irradiation, wherein plastic 'T' is hardly found by being attached to paper due to near transparency, and the morphology of metal 'T' and plastic 'T' can be easily observed in a terahertz image, and the two have different contrast ratios, so that the composite material object is very easy to distinguish. The graphene flexible terahertz wave detector can also realize terahertz wave imaging of a hidden object when being attached to a curved surface in a conformal manner under the irradiation of 2.52THz laser, the naked eye can not distinguish the anti-counterfeiting watermark of the RMB, the anti-counterfeiting watermark has different terahertz wave transmittance with surrounding paper under the irradiation of 2.52THz terahertz waves, and an anti-counterfeiting watermark 'orchid' terahertz photocurrent image with 63 multiplied by 53 pixels can be obtained by carrying out two-dimensional raster scanning imaging on a red dotted line frame region. The graphene flexible terahertz wave detector has a crucial role in wearable imaging electronic equipment.
Example 5
As shown in fig. 12, a preparation method of a graphene flexible terahertz wave detector includes:
s1, performing plasma etching treatment on one surface of an obtained substrate layer 4 to form a hydrophilic surface;
S2, transferring the graphene layer 2 on one surface of the substrate layer 4 subjected to hydrophilic treatment, and performing patterning treatment on the graphene layer 2 to obtain a single-layer graphene film;
And S3, carrying out photoetching, sputtering, deposition or evaporation treatment on two end parts of the graphene layer 2 to form a source metal electrode 1 and a drain metal electrode 3 of an asymmetric electrode so as to obtain the graphene flexible terahertz wave detector.
For specific limitation of the preparation method of the graphene flexible terahertz wave detector, reference may be made to the above limitation of the graphene flexible terahertz wave detector, and no further description is given here. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The graphene flexible terahertz wave detector and the preparation method thereof are used for solving the technical problems of how to design a flexible terahertz wave detector, so as to improve the integration level, detection dimension and application range of a terahertz wave detection and imaging system, and improve the detection performance and curved surface imaging capability of the terahertz wave detector. The flexible terahertz wave detector provided by the application has good flexibility and stability, supports wide-spectrum detection of ultraviolet to millimeter wave frequency bands containing terahertz waves, realizes high-resolution terahertz wave imaging of composite material objects and hidden objects under conformal attachment with a flexible curved surface, and has good application prospects.
In this specification, each embodiment is described in a progressive manner, and all the embodiments are directly the same or similar parts referring to each other, and each embodiment mainly describes differences from other embodiments. In particular, for the method embodiments, since they are substantially similar to the apparatus embodiments, the description is relatively simple, with reference to the description of the apparatus embodiments in part. It should be noted that, any combination of the technical features of the foregoing embodiments may be used, and for brevity, all of the possible combinations of the technical features of the foregoing embodiments are not described, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples represent only a few preferred embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that modifications and substitutions can be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and substitutions should also be considered to be within the scope of the present invention. Therefore, the protection scope of the patent of the invention is subject to the protection scope of the claims.
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