A construction and verification method of a single-layer graphene terahertz pyroelectric detector

Abstract

The present invention discloses a construction and verification method of a single-layer graphene terahertz thermoelectric detector, which belongs to the technical field of terahertz detector design, and includes the following steps: constructing a full dielectric substrate; obtaining a single-layer graphene, and constructing a single-layer graphene terahertz thermoelectric detector based on the full dielectric substrate; verifying the single-layer graphene terahertz thermoelectric detector using X-polarized terahertz waves to obtain thermoelectric potential and photovoltage signals; the full dielectric substrate is composed of a complete area without any graphics and a specific graphic supersurface area, and the supersurface locally enhances the absorption of terahertz waves by graphene to form a thermoelectric potential; the detector provided by the present invention has a simple structure, does not require the traditional symmetrical electrode thermoelectric detector to accurately control the incident light spot position, and does not involve the complex electrode preparation process of the asymmetric electrode thermoelectric detector. The present invention is supported by the "Central Guidance Local Science and Technology Development Project (No.: 2021ZYD0039)".

Description

Technical Field

[0001] The invention belongs to the technical field of terahertz detector design, and in particular relates to a structure and verification method of a single-layer graphene terahertz thermoelectric detector. Background Art

[0002] Terahertz detectors are one of the basic research in the terahertz field. More and more terahertz detection principles have been reported, among which the most widely used is the thermoelectric effect. The working principle of thermoelectric detectors is mainly based on the temperature difference potential of materials. These materials generally have suitable thermal conductivity and electrical conductivity, among which graphene materials are particularly popular. Graphene terahertz thermoelectric detectors can be divided into symmetrical electrodes and asymmetrical electrodes according to electrode classification. The positive and negative electrodes used in symmetrical electrode graphene thermoelectric detectors are the same metal, and the generation of electrical signals is mainly through the terahertz wave irradiating different positions of graphene to form a temperature difference; when this detector is working, it is required that the light beam spot cannot cover the entire photosensitive area, nor can it irradiate the central area, but can only irradiate one side of one of the electrodes; when the photosensitive channel is narrow, the irradiation position of the light beam needs to be precisely controlled, and the control of the light spot position is extremely difficult, so this type of detector application is basically only suitable for laboratories. The positive and negative electrodes of the asymmetric electrode graphene thermoelectric detector are dissimilar metals. The terahertz beam can irradiate the entire device. Dissimilar metals have different thermal conductivities, thus forming a temperature difference potential between the two metal electrodes. However, the preparation process of different metal electrodes on the same device is difficult and costly. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for constructing and verifying a single-layer graphene terahertz thermoelectric detector, provides a method for constructing a single-layer graphene terahertz thermoelectric detector with regionalized electromagnetic absorption enhancement, and produces differences in terahertz wave energy absorption by different regions of the single-layer graphene, thereby forming a temperature difference potential between different regions.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0005] The present invention provides a construction and verification method of a single-layer graphene terahertz pyroelectric detector, comprising the following steps:

[0006] S1. constructing a full dielectric substrate;

[0007] S2, obtaining a single-layer graphene, and constructing a single-layer graphene terahertz thermoelectric detector based on a full dielectric substrate;

[0008] S3. Verify the single-layer graphene terahertz thermoelectric detector using X-polarized terahertz waves.

[0009] The beneficial effects of the present invention are as follows: a construction and verification method of a single-layer graphene terahertz thermoelectric detector provided by the present invention divides high-resistance silicon into two regions through conventional etching technology, one region retains complete high-resistance silicon, and the other region is etched into a special patterned super-surface array to obtain a full dielectric substrate, and a single-layer graphene is spread flat on the full dielectric substrate, and then two gold electrodes are evaporated onto the surface of the single-layer graphene, and the positions of the two gold electrodes are respectively located in the complete high-resistance silicon region and the super-surface high-resistance silicon region to form a single-layer graphene terahertz thermoelectric detector, so that different regions of the single-layer graphene have different absorption of terahertz wave energy, thereby forming a temperature difference potential between different regions. The single-layer graphene terahertz thermoelectric detector provided by this scheme uses symmetrical electrodes, is easy to manufacture, and allows the terahertz spot to cover the entire photosensitive area. The present invention does not require the traditional symmetrical electrode thermoelectric detector to accurately control the position of the incident light spot, nor does it require the complex electrode preparation process of the asymmetric electrode thermoelectric detector.

[0010] Furthermore, the step S1 comprises the following steps:

[0011] S11, using ultraviolet curing glue to bond high-resistance silicon to quartz to obtain an initial all-dielectric substrate;

[0012] S12, etching high-resistance silicon to obtain a full dielectric substrate.

[0013] The beneficial effect of adopting the above further scheme is: high-resistance silicon is etched through an etching process so that the high-resistance silicon forms two regions, one region retains the complete high-resistance silicon, and the other region is etched into a special patterned supersurface array, providing a basis for flattening graphene to obtain a single-layer graphene terahertz thermoelectric detector.

[0014] Further, the all-dielectric substrate includes a first region having complete high-resistance silicon and a second region having a patterned metasurface array;

[0015] The second region is composed of 20×20 cells;

[0016] The structure of each of the cells is an incomplete ellipse strip in which both ends of an ellipse are cut into semicircles.

[0017] The beneficial effect of adopting the above further solution is that the absorption rate of the single-layer graphene to the X-polarized terahertz wave of 1.2 THz is significantly enhanced by the second region composed of 20×20 cells.

[0018] Furthermore, the structural parameters of the cell are as follows;

[0019] The height h is 80 μm;

[0020] The lattice period P is 160 μm;

[0021] The major axis I of the ellipse is 160 μm;

[0022] The minor axis W of the ellipse is 60 μm;

[0023] The cutting semicircle radius R is 30 μm.

[0024] The beneficial effect of adopting the above further scheme is that each graphic unit is an incomplete elliptical strip with both ends cut by semicircles, which realizes a strong local effect on the terahertz wave incident from the bottom, enhances the absorption of the terahertz wave by the single-layer graphene, causes the temperature of the single-layer graphene on the second area to rise, thereby forming a temperature difference potential with the single-layer graphene on the first area.

[0025] Furthermore, the step S2 comprises the following steps:

[0026] S21, depositing a single layer of graphene onto the upper side of the copper substrate by chemical vapor deposition;

[0027] S22, transferring the single-layer graphene on the copper substrate to the upper side of the all-dielectric substrate;

[0028] S23, respectively evaporating a first metal electrode and a second metal electrode onto two ends of the surface of the single-layer graphene to obtain a single-layer graphene terahertz pyroelectric detector.

[0029] The beneficial effects of adopting the above further scheme are: through symmetrical vapor deposition electrodes, it is easy to manufacture and allows the terahertz spot to cover the entire photosensitive area, thereby obtaining a single-layer graphene terahertz pyroelectric detector. There is no need for the traditional symmetrical electrode pyroelectric detector to precisely control the position of the incident light spot, nor is there a need for the complex electrode preparation process of the asymmetric electrode pyroelectric detector.

[0030] Furthermore, the channel distance between the first metal electrode and the second metal electrode is 5 mm.

[0031] The beneficial effects of adopting the above further scheme are:

[0032] Furthermore, step S3 includes the following steps:

[0033] S31, injecting an X-polarized terahertz wave with a frequency of 1.2 THz into the single-layer graphene terahertz thermoelectric detector from the bottom to obtain a terahertz energy absorption rate of the first region and a terahertz energy absorption rate of the second region;

[0034] S32, respectively connecting a voltmeter and an ammeter to the first metal electrode and the second metal electrode to obtain an electrical signal of the first metal electrode and an electrical signal of the second metal electrode;

[0035] S33, determining whether the terahertz energy absorption rate of the first area is less than a first preset terahertz energy absorption rate threshold, if so, proceeding to step S34, otherwise returning to step S1;

[0036] S34, determining whether the terahertz energy absorption rate of the second area is greater than a second preset terahertz energy absorption rate threshold, if so, proceeding to step S35, otherwise returning to step S1;

[0037] S35. Based on the terahertz energy absorption rate of the first region and the terahertz energy absorption rate of the second region, and normalizing the first metal electrode electrical signal and the second metal electrode electrical signal, the thermoelectric potential and the photovoltage signal are obtained to complete the verification of the single-layer graphene terahertz thermoelectric detector.

[0038] The beneficial effects of adopting the above further scheme are as follows: X-polarized terahertz waves are incident from the bottom of the device, and in the first region, the terahertz absorption is only acted on by the single-layer graphene alone, and the absorption rate of the single-layer graphene is limited. In the second region, the loss of the all-dielectric metasurface itself is very weak, and there is almost no absorption, but the addition of the metasurface significantly enhances the absorption rate of the single-layer graphene at 1.2 THz. The metasurface localizes the terahertz energy in the dielectric column. Since the metasurface medium itself hardly loses electromagnetic energy, the energy will be conducted to the graphene above the metasurface. Based on the terahertz energy absorption rate of the first region and the terahertz energy absorption rate of the second region, and normalizing the first metal electrode electrical signal and the second metal electrode electrical signal, the thermoelectric potential and photovoltage signals are obtained, and the verification of the single-layer graphene terahertz thermoelectric detector can be completed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The figure is a flowchart of the steps of the construction and verification method of the single-layer graphene terahertz pyroelectric detector in an embodiment of the present invention.

[0040] FIG. 2( a ) is a top view of a cellular structure of a second region in an embodiment of the present invention.

[0041] FIG. 2( b ) is a side view of the cellular structure of the second region in an embodiment of the present invention.

[0042] Figure 3 Schematic diagram of a single-layer graphene terahertz pyroelectric detector in an embodiment of the present invention.

[0043] Figure 4 This is a comparison chart of the absorption rates of a single-layer graphene with and without a patterned supersurface in an embodiment of the present invention.

[0044] FIG. 5( a ) is a diagram showing the local distribution of the terahertz wave magnetic field in the patterned metasurface in an embodiment of the present invention.

[0045] FIG. 5( b ) is a diagram showing the local distribution of the electric field of a terahertz wave in a patterned metasurface in an embodiment of the present invention.

[0046] Figure 6Graph showing the normalized voltage response of the single-layer graphene terahertz pyroelectric detector in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0048] When the terms "include" and / or "comprising" are used in this specification, these terms indicate the existence of the stated features, integers, steps, operations, elements and / or parts, but do not exclude the existence and / or addition of one or more other features, integers, steps, operations, elements, parts and / or groups thereof.

[0049] like Figure 1 As shown, in one embodiment of the present invention, the present invention provides a construction and verification method of a single-layer graphene terahertz pyroelectric detector, comprising the following steps:

[0050] S1, constructing a full dielectric substrate;

[0051] The step S1 comprises the following steps:

[0052] S11, using ultraviolet curing glue to bond high-resistance silicon with a resistivity of 0.03S / m to quartz (silicon dioxide) to obtain an initial all-dielectric substrate;

[0053] S12, etching high-resistance silicon to obtain a full dielectric substrate;

[0054] The all-dielectric substrate comprises a first region having complete high-resistance silicon and a second region having a patterned metasurface array;

[0055] The second region is composed of 20×20 cells;

[0056] The structure of each of the cells is an incomplete ellipse strip with both ends of the ellipse cut into semicircles;

[0057] As shown in FIG. 2( a ) and FIG. 2( b ), the structural parameters of the cell are as follows;

[0058] The height h is 80 μm;

[0059] The lattice period P is 160 μm;

[0060] The major axis I of the ellipse is 160 μm;

[0061] The minor axis W of the ellipse is 60 μm;

[0062] The cutting semicircle radius R is 30 μm;

[0063] S2, obtaining a single-layer graphene, and constructing a single-layer graphene terahertz thermoelectric detector based on a full dielectric substrate;

[0064] The step S2 comprises the following steps:

[0065] S21, depositing a single layer of graphene onto the upper side of the copper substrate by chemical vapor deposition;

[0066] S22, transferring the single-layer graphene on the copper substrate to the upper side of the all-dielectric substrate;

[0067] S23, respectively evaporating a first metal electrode and a second metal electrode onto both ends of the surface of the single-layer graphene to obtain a single-layer graphene terahertz pyroelectric detector, such as Figure 3 As shown;

[0068] The channel distance between the first metal electrode and the second metal electrode is 5 mm;

[0069] S3. Use X-polarized terahertz waves to verify the single-layer graphene terahertz thermoelectric detector and obtain thermoelectric potential and photovoltage signals;

[0070] The step S3 comprises the following steps:

[0071] S31, injecting an X-polarized terahertz wave with a frequency of 1.2 THz into the single-layer graphene terahertz thermoelectric detector from the bottom to obtain a terahertz energy absorption rate of the first region and a terahertz energy absorption rate of the second region;

[0072] S32, respectively connecting a voltmeter and an ammeter to the first metal electrode and the second metal electrode to obtain an electrical signal of the first metal electrode and an electrical signal of the second metal electrode;

[0073] like Figure 4 As shown, the X-polarized terahertz wave is incident from the bottom of the single-layer graphene terahertz thermoelectric detector. In the first area with complete high-resistance silicon, the terahertz absorption is only caused by the single-layer graphene alone. It can be seen that the absorption rate of the single-layer graphene at 1.2 THz is only 25%; in the second area with the patterned metasurface, the loss of the all-dielectric metasurface itself is very weak, with almost no absorption, but the addition of the metasurface significantly enhances the absorption rate of the single-layer graphene at 1.2 THz to 90%;

[0074] As shown in Figure 5(a) and Figure 5(b), the metasurface is irradiated with a 1.2 THz wave, and the electromagnetic field distribution of the graphene structure on the metasurface is monitored. It can be seen from the monitoring of the electromagnetic field distribution of the graphene structure on the metasurface at 1.2 THz that the metasurface localizes the terahertz energy in the dielectric column. Since the metasurface medium itself hardly loses electromagnetic energy, this energy will be conducted to the graphene above the metasurface, which is the main source of enhanced graphene terahertz energy absorption. The huge difference in terahertz energy absorption between the single-layer graphene in the first region with complete high-resistance silicon and the second region with supersurface high-resistance silicon will cause a temperature difference potential between the two regions.

[0075] S33, determining whether the terahertz energy absorption rate of the first area is less than a first preset terahertz energy absorption rate threshold, if so, proceeding to step S34, otherwise returning to step S1;

[0076] In this embodiment, the first preset terahertz energy absorption rate threshold is 25%;

[0077] S34, determining whether the terahertz energy absorption rate of the second area is greater than a second preset terahertz energy absorption rate threshold, if so, proceeding to step S35, otherwise returning to step S1;

[0078] In this embodiment, the second preset terahertz energy absorption rate threshold is 90%;

[0079] S35, based on the terahertz energy absorption rate of the first region and the terahertz energy absorption rate of the second region, and normalizing the first metal electrode electrical signal and the second metal electrode electrical signal, to obtain a thermoelectric potential and a photovoltage signal;

[0080] like Figure 6 As shown, the device is irradiated from the bottom with 1.2 THz and the output electrical signal is detected. As the terahertz wave is switched on and off, the voltage is significantly enhanced. In contrast, the present invention demonstrates the performance of a device without a metasurface array on the substrate. The graphene is laid flat on a complete high-resistance silicon. This is a traditional symmetrical electrode thermoelectric detection structure. It can be seen that when the terahertz wave is irradiated from the bottom, there is no change in the electrical signal.

[0081] The present invention provides a construction and verification method of a single-layer graphene terahertz thermoelectric detector, in which a single-layer graphene is flattened on a specially designed all-dielectric substrate, and gold electrodes are used at both ends of the graphene surface; the all-dielectric substrate is composed of a complete area without any pattern and a specific patterned super-surface area, the super-surface area has a strong local effect on the terahertz wave incident from the bottom, the localized terahertz electromagnetic energy is conducted to the upper single-layer graphene, the graphene absorbs the terahertz wave, causes the temperature of the graphene in the corresponding area to rise, and thus forms a temperature difference potential with the graphene on the complete dielectric area; the single-layer graphene terahertz thermoelectric detector provided by the present invention has a simple structure, does not require the precise control of the incident light spot position like a traditional symmetrical electrode thermoelectric detector, and does not involve a complex electrode preparation process like an asymmetric electrode thermoelectric detector.

[0082] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A construction and verification method of a single-layer graphene terahertz pyroelectric detector, characterized in that: The steps include: S1, constructing a full dielectric substrate; S2, obtaining a single-layer graphene, and constructing a single-layer graphene terahertz thermoelectric detector based on a full dielectric substrate; S3. Use X-polarized terahertz waves to verify the single-layer graphene terahertz thermoelectric detector and obtain thermoelectric potential and photovoltage signals; The step S1 comprises the following steps: S11, using ultraviolet curing glue to bond high-resistance silicon to quartz to obtain an initial all-dielectric substrate; S12, etching high-resistance silicon to obtain a full dielectric substrate; The all-dielectric substrate comprises a first region having complete high-resistance silicon and a second region having a patterned metasurface array; The second region is composed of 20×20 cells; The structure of each of the cells is an incomplete ellipse strip with both ends of the ellipse cut into semicircles; The step S2 comprises the following steps: S21, depositing a single layer of graphene onto the upper side of the copper substrate by chemical vapor deposition; S22, transferring the single-layer graphene on the copper substrate to the upper side of the all-dielectric substrate; S23, respectively evaporating a first metal electrode and a second metal electrode onto two ends of the surface of the single-layer graphene to obtain a single-layer graphene terahertz pyroelectric detector; The step S3 comprises the following steps: S31, injecting an X-polarized terahertz wave with a frequency of 1.2 THz into the single-layer graphene terahertz thermoelectric detector from the bottom to obtain a terahertz energy absorption rate of the first region and a terahertz energy absorption rate of the second region; S32, respectively connecting a voltmeter and an ammeter to the first metal electrode and the second metal electrode to obtain an electrical signal of the first metal electrode and an electrical signal of the second metal electrode; S33, determining whether the terahertz energy absorption rate of the first area is less than a first preset terahertz energy absorption rate threshold, if so, proceeding to step S34, otherwise returning to step S1; S34, determining whether the terahertz energy absorption rate of the second area is greater than a second preset terahertz energy absorption rate threshold, if so, proceeding to step S35, otherwise returning to step S1; S35. Based on the terahertz energy absorption rate of the first region and the terahertz energy absorption rate of the second region, the first metal electrode electrical signal and the second metal electrode electrical signal are normalized to obtain a thermoelectric potential and a photovoltage signal.

2. The structure and verification method of the single-layer graphene terahertz pyroelectric detector according to claim 1, characterized in that: The structural parameters of the cell are as follows; high h 80μm; Lattice period P 160μm; Ellipse major axis I 160μm; Ellipse minor axis W 60μm; Cutting semicircle radius R is 30μm.

3. The structure and verification method of the single-layer graphene terahertz pyroelectric detector according to claim 1, characterized in that: The channel distance between the first metal electrode and the second metal electrode is 5 mm.

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