Detection element for electromagnetic wave detection device, and electromagnetic wave detection device

Abstract

To provide a detection element for an electromagnetic wave detection device that has a fast response speed and low noise, and an electromagnetic wave detection device equipped with the same. [Solution] A detection element for an electromagnetic wave detection device having a pair of conductive wires for detecting electromagnetic waves from infrared to microwave, wherein the pair of conductive wires consists of a pair of conductive wires comprising two conductive wires containing different conductive types and having different Seebeck coefficients, a pair of conductive wires comprising two conductive wires containing the same conductive type and having different Seebeck coefficients, or a pair of conductive wires comprising one conductive wire containing different conductive types or the same conductive type and having two regions with different Seebeck coefficients, and an electromagnetic wave detection device equipped therewith.

Description

[Technical Field]

[0001] This disclosure relates to a detection element for an electromagnetic wave detection device and an electromagnetic wave detection device. [Background technology]

[0002] Conventional electromagnetic wave detection devices exist that can detect electromagnetic waves ranging from infrared to microwave, such as terahertz waves. The detection element of an electromagnetic wave detection device generally has a structure in which an electromagnetic wave absorber that absorbs electromagnetic waves such as terahertz waves and generates heat is applied to the junction between a P-type metal member and an N-type metal member provided on a substrate (see, for example, Patent Document 1). Furthermore, detection elements for electromagnetic wave detection devices that utilize individual P-type and N-type carbon nanotube films formed on a substrate are also known (see, for example, Patent Document 1). In this detection element, an electromotive force is generated at the PN junction of the carbon nanotube due to the heat generated by absorbing electromagnetic waves such as terahertz waves. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-23554 [Patent Document 2] International Public Gazette 2018 / 207780 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, these detection elements generate heat through the absorption of electromagnetic waves, which then dissipates into the electromagnetic wave absorber or substrate. As a result, their response speed is low. Furthermore, in detection elements using P-type and N-type carbon nanotube films alone, the high resistance of the carbon nanotube film results in increased noise.

[0005] Therefore, an object of the present disclosure is to provide a detection element for an electromagnetic wave detection device having high response speed and low noise, and an electromagnetic wave detection device including the same. [Means for Solving the Problem]

[0006] Means for solving the problem include the following aspects. <1> A detection element for an electromagnetic wave detection device that has a pair of conductive wires and detects electromagnetic waves from infrared rays to microwaves, wherein the pair of conductive wires is a pair of conductive wires composed of two conductive wires containing nanocarbons of different conductivity types and having different Seebeck coefficients, a pair of conductive wires composed of two conductive wires containing nanocarbons of the same conductivity type and having different Seebeck coefficients, or a pair of conductive wires composed of one conductive wire containing nanocarbons of different conductivity types or nanocarbons of the same conductivity type and having two regions with different Seebeck coefficients, which is the detection element for an electromagnetic wave detection device. <2> The detection element for an electromagnetic wave detection device according to <1>, wherein the nanocarbon of the same conductivity type is P-type nanocarbon. <3> The detection element for an electromagnetic wave detection device according to <1> or <2>, wherein the nanocarbon is a carbon nanotube. <4> The detection element for an electromagnetic wave detection device according to any one of <1> to <3>, wherein a detection portion of the detection element is in an unsupported state. <5> The detection element for an electromagnetic wave detection device according to any one of claims 1 to <4>, wherein a plurality of each of the two conductive wires and the one conductive wire are provided and form a bundle. <6> A detection element for an electromagnetic wave detection device that has a pair of conductive wires and detects electromagnetic waves from infrared rays to microwaves, wherein a detection portion of the detection element is A junction of a pair of conductive wires consisting of two conductive wires containing nanocarbons of different conductivity types or nanocarbons of the same conductivity type and having different Seebeck coefficients, A stitched portion of a pair of conductive wires consisting of two conductive wires containing nanocarbons of different conductivity types or nanocarbons of the same conductivity type and having different Seebeck coefficients, A twisted portion of a pair of conductive wires consisting of two conductive wires containing nanocarbons of different conductivity types or nanocarbons of the same conductivity type and having different Seebeck coefficients, A woven portion of a pair of conductive wires consisting of two conductive wires containing nanocarbons of different conductivity types or nanocarbons of the same conductivity type and having different Seebeck coefficients, or A boundary between two regions of a single conductive wire having two regions containing nanocarbons of different conductivity types or nanocarbons of the same conductivity type and having different Seebeck coefficients, A detection element for an electromagnetic wave detection device comprising at least <7> The detection element for an electromagnetic wave detection device according to <6>, wherein the nanocarbons of the same conductivity type are P-type nanocarbons. <8> The detection element for an electromagnetic wave detection device according to <6> or <7>, wherein the nanocarbon is a carbon nanotube. <9> The detection element for an electromagnetic wave detection device according to any one of <6> to <8>, wherein a detection portion of the detection element is in an unsupported state. <10> The detection element for an electromagnetic wave detection device according to any one of <6> to <9>, comprising a plurality of each of said two conductive wires and said one conductive wire bundled together. <11> Comprising the detection element for an electromagnetic wave detection device according to any one of claims 1 to 10, An electromagnetic wave detection device that detects electromagnetic waves from infrared rays to microwaves.

Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a detection element for an electromagnetic wave detection device having fast response speed and low noise, and an electromagnetic wave detection device including the same. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing an example of an electromagnetic wave detection device in this disclosure. [Figure 2] This is a schematic diagram showing an example of a detection element (a pair of conductive wires) for an electromagnetic wave detection device according to the first embodiment of this disclosure. [Figure 3] This is a schematic diagram showing an example of a detection element (a pair of conductive wires) for an electromagnetic wave detection device according to the second embodiment of this disclosure. [Figure 4] This is a schematic diagram showing an example of a detection element (a pair of conductive wires) for an electromagnetic wave detection device according to the third embodiment of this disclosure. [Figure 5] This is a schematic diagram showing an example of a detection element (a pair of conductive wires) for an electromagnetic wave detection device according to the fourth embodiment of this disclosure. [Figure 6] This is a schematic diagram showing an example of a detection element (a pair of conductive wires) for an electromagnetic wave detection device according to the fifth embodiment of this disclosure. [Figure 7] This graph shows the switching characteristics of the detection element for the electromagnetic wave detection device of Example 1. [Figure 8] This graph shows the switching characteristics of the detection element for the electromagnetic wave detection device in Example 2. [Figure 9] This graph shows the switching characteristics of the detection element for the electromagnetic wave detection device in Example 3. [Figure 10] This graph shows the switching characteristics of the detection element for the electromagnetic wave detection device of Example 4. [Modes for carrying out the invention]

[0009] The following describes an example of an embodiment of this disclosure. These descriptions and examples are illustrative and do not limit the scope of the invention. In the numerical ranges described in stages within this specification, one numerical range is described The upper or lower limits may be replaced with the upper or lower limits of other stepped numerical ranges. Furthermore, within the numerical ranges described herein, the upper or lower limits of those ranges may be replaced with the values ​​shown in the examples. Each component in the composition may contain multiple types of the relevant substance. When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of those multiple substances present in the composition.

[0010] <Detection element for electromagnetic wave detection device / Electromagnetic wave detection device> The electromagnetic wave detection device of this disclosure comprises a detection element for electromagnetic wave detection devices (hereinafter also simply referred to as the "detection element"). The detection element is one of the detection elements for electromagnetic wave detection devices described in the first disclosure to the second disclosure below.

[0011] The first detection element for the electromagnetic wave detection device of this disclosure has a pair of conductive wires. Furthermore, in the first detection element of the present disclosure, the pair of conductive wires is a pair of conductive wires consisting of two conductive wires containing different conductive types and having different Seebeck coefficients, a pair of conductive wires consisting of two conductive wires containing the same conductive type and having different Seebeck coefficients, or a pair of conductive wires consisting of one conductive wire containing different conductive types or the same conductive type and having two regions with different Seebeck coefficients.

[0012] In the first detection element of this disclosure, a conductive wire containing nanocarbon is applied to a pair of conductive wires. Because the conductive wire containing nanocarbon has lower resistance than a carbon nanotube film alone, the signal-to-noise ratio (S / N) is higher, resulting in less noise and a faster response speed.

[0013] The second detection element for the electromagnetic wave detection device of this disclosure has a pair of conductive wires. Furthermore, in the second detection element of this disclosure, the detection unit of the detection element is: The joint between a pair of conductive wires, each consisting of two conductive wires containing different types of nanocarbon or the same type of nanocarbon, and having different Seebeck coefficients. A joint between two conductive wires, each containing nanocarbon of different conductivity types or the same conductivity type, and having different Seebeck coefficients. A twisted portion of a pair of conductive wires consisting of two conductive wires containing different types of conductive nanocarbon or the same type of conductive nanocarbon, and having different Seebeck coefficients. A braided section of a pair of conductive wires consisting of two conductive wires containing different types of conductive nanocarbon or the same type of conductive nanocarbon, but with different Seebeck coefficients, or The boundary between two regions of a conductive wire having two regions with different Seebeck coefficients, containing nanocarbons of different conductivity types or the same conductivity type. It consists of at least these.

[0014] In the detection element of the second disclosure, a conductive wire containing nanocarbon is applied to a pair of conductive wires. Because the conductive wire containing nanocarbon has lower resistance than a carbon nanotube film alone, the signal-to-noise ratio (S / N) is higher, resulting in less noise. Conductive wires containing nanocarbon absorb electromagnetic waves and generate heat without the need for electromagnetic wave absorbing materials. The detection section (i.e., the part where electromotive force is generated by heat generation) is made up of the knot, stitch, twist, weave, and boundary sections described above. In the knot section, a pair of conductive wires are tied together; in the stitch section, a pair of conductive wires are stitched together; in the twist section, a pair of conductive wires are twisted together; and in the weave section, a pair of conductive wires are knitted or woven in. The boundary section is made up of a single conductive wire. By applying these sections to the detection section where electromotive force is generated by the absorption of electromagnetic waves by conductive wires containing nanocarbon, noise is reduced and the response speed is increased.

[0015] In the first and second detection elements of this disclosure, it is preferable that the detection portion of the detection element is in an unsupported state. In the first detection element of this disclosure, the conductive wire containing nanocarbon absorbs electromagnetic waves and generates heat without the addition of an electromagnetic wave absorbing material. Furthermore, the detection portion of the detection element, which is composed of the contact portion of a pair of conductive wires (i.e., the part where electromotive force is generated due to the heat generation), is in an unsupported state. Therefore, the heat generated by the absorption of electromagnetic waves in the conductive wire containing nanocarbon does not diffuse to the electromagnetic wave absorbing material or to the substrate supporting the detection portion of the conductive wire. As a result, the response speed is increased. In the second detection element of this disclosure, a conductive wire containing nanocarbon is applied to a detection unit that generates an electromotive force by absorbing electromagnetic waves, and by making the detection unit unsupported, the heat generated by the absorption of electromagnetic waves in the conductive wire containing nanocarbon does not diffuse to the electromagnetic wave absorber or the substrate supporting the detection unit of the conductive wire. As a result, the response speed is increased.

[0016] Here, the state in which the detection part of the detection element is unsupported means that the detection part of the detection element (i.e., the part where electromotive force is generated due to heat generation) is not in contact with any other component. Furthermore, "two conductive wires with different Seebeck coefficients" are preferably two conductive wires where the difference in Seebeck coefficients is, for example, 1 μV / K or more in absolute value (preferably 10 μV / K or more, more preferably 20 μV / K or more). Similarly, "two regions with different Seebeck coefficients in a single conductive wire" are preferably two regions where the difference in Seebeck coefficients is, for example, 1 μV / K or more in absolute value (preferably 10 μV / K or more, more preferably 20 μV / K or more). Furthermore, a larger absolute value in the difference between Seebeck coefficients is preferable because it results in a higher amount of electromotive force generated by heat.

[0017] The Seebeck coefficient is measured and calculated as follows: The thermoelectric power generated is measured using a thermoelectric property measuring device while one end of the conductive wire or region of the conductive wire is heated to create a temperature difference of 0.5 to 30°C between the two ends of the conductive wire or region of the conductive wire. Then, preferably, the temperature difference is varied to about three levels during the measurement, and the Seebeck coefficient is calculated from the arithmetic mean of the obtained thermoelectric powers.

[0018] The electromagnetic wave detection device (or detection element for electromagnetic wave detection device) of this disclosure is a device (or element) that detects electromagnetic waves from infrared to microwave (specifically, electromagnetic waves with wavelengths of 780 nm to 1 mm), but it is particularly effective to apply it to a terahertz wave detection device that detects terahertz waves with frequencies of 0.3 GHz to 30 THz and wavelengths of 0.03 to 3 mm.

[0019] The following describes in detail an embodiment of an electromagnetic wave detection device and detection element of this disclosure, with reference to the drawings.

[0020] <Electromagnetic wave detection device> As shown in Figure 1, the electromagnetic wave detection device 10 according to this embodiment includes, for example, a detection element 12, an amplifier 14 that amplifies the analog signal (electromotive force signal) from the detection element 12, an analog-to-digital converter 16 that converts the amplified analog signal (electromotive force signal) into a digital signal (electric pulse or optical pulse, etc.), and a measuring instrument 18 that detects electromagnetic waves from the digital signal from the analog-to-digital converter 16 and measures the characteristics of the electromagnetic waves (wavelength, intensity, etc.). The detection element 12 includes, for example, a pair of conductive wires 12A, electrodes 12B that electrically connect both ends of the pair of conductive wires 12A, and supports 12C that support both ends of the pair of conductive wires 12A.

[0021] Thus, in the detection element 12, the detection unit (the detection unit for the pair of conductive wires 12A) is in an unsupported state. Here, the detection part of the detection element 12 (the detection part of the pair of conductive wires 12A) is composed of the following parts. In these parts, when the conductive wires containing nanocarbon absorb electromagnetic waves and generate heat, an electromotive force is generated by the heat generated. 1) Contact area of ​​two conductive wires containing different types of conductive nanocarbon and having different Seebeck coefficients 2) Contact area of ​​two conductive wires containing the same type of conductive nanocarbon but with different Seebeck coefficients 3) The boundary between two regions of a conductive wire that contains nanocarbons of different conductivity types or nanocarbons of the same conductivity type and have different Seebeck coefficients.

[0022] Electrode 12B is composed of a metal such as Al, Mo, Cr, Ta, Ti, Au, Ag, or an alloy thereof. The support 12C is composed of, for example, a metal member made of steel or other metal, a resin member, or the like.

[0023] The electromagnetic wave detection device 10 is not limited to the above configuration, except for the pair of conductive wires of the detection element 12, and any electromagnetic wave detection device with a well-known configuration may be used.

[0024] <Detection element for electromagnetic wave detection device> The following describes the detection elements 110, 210, 310, 410, and 510 according to the first to fifth embodiments, which are applied to the detection element 12.

[0025] (First Embodiment) As shown in Figure 2, the detection element 110 according to the first embodiment has, for example, a pair of conductive wires 112. The pair of conductive wires 112 consists of two conductive wires 114A and 114B that contain nanocarbons of different conductivity types or the same conductivity type, and have different Seebeck coefficients. When two conductive wires 114A and 114B contain nanocarbon of the same conductivity type, the Seebeck coefficients of the two conductive wires 114A and 114B can be made different by changing either the type or amount of dopant used to dope the nanocarbon in the two conductive wires 114A and 114B.

[0026] The combinations of the two conductive wires 114A and 114B are as follows: 1) A combination of a P-type conductive wire 114A containing P-type nanocarbon that is either undoped or doped with a P-type dopant, and an N-type conductive wire 114B containing N-type nanocarbon that is doped with an N-type dopant. 2) A combination of a P-type conductive wire 114A containing P-type nanocarbon that is either undoped or doped with a P-type dopant, and a P-type conductive wire 114B containing P-type nanocarbon that is doped with more P-type dopant than the P-type nanocarbon contained in the P-type conductive wire 114A. 3) A combination of an N-type conductive wire 114A containing N-type nanocarbon doped with an N-type dopant, and an N-type conductive wire 114B containing N-type nanocarbon doped with more N-type dopant than the N-type nanocarbon contained in the N-type conductive wire 114A.

[0027] Among these combinations, the combination of P-type conductive wire 114A and P-type conductive wire 114B is preferred because it is less prone to deterioration of carrier characteristics and has high durability. In other words, it is preferable that the nanocarbon of the same conductive type be P-type nanocarbon.

[0028] The two conductive wires 114A and 114B are, for example, each made of conductive wire such as nanocarbon yarn. The two conductive wires 114A and 114B may be the same type of conductive wire or different types of conductive wire.

[0029] Details of the two conductive wires 114A and 114B will be described later.

[0030] The detection portion 116 of the detection element 110 is composed of a joint portion 118 of a pair of conductive wires 112, which consist of two conductive wires 114A and 114B. Specifically, one end of the two conductive wires 114A and 114B is joined together, and this joint portion 118 constitutes the detection portion 116 of the detection element 110.

[0031] Examples of knots 118 include knots formed by a single knot or figure-eight knot between two conductive wires 114A and 114B; knots formed by a square knot, single connection or double connection between two conductive wires 114A and 114B; knots formed by wrapping one conductive wire 114B around the other conductive wire 114A and making a single or double knot; and other knots formed by connecting two conductive wires 114A and 114B using well-known methods.

[0032] The knot 118 can also be exemplified by a knot made of a binding material that brings the two conductive wires 114A and 114B into contact with each other. Examples of knotting materials include nanocarbon yarn, nanocarbon ribbon, yarn or ribbon of natural fibers (silk, cotton, etc.), yarn or ribbon of chemical fibers (polyester fiber, nylon fiber, etc.), and blended yarns of natural and chemical fibers.

[0033] In Figure 2, an example is shown in which the detection section 116 of the detection element 110 is constructed by forming a knot 118 with two conductive wires 114A and 114B that are bundled together.

[0034] (Second embodiment) As shown in Figure 3, the detection element 210 according to the second embodiment has a pair of conductive wires 212. The pair of conductive wires 212 consists of two conductive wires 214A and 214B that contain nanocarbons of different conductivity types or the same conductivity type, and have different Seebeck coefficients. When two conductive wires 214A and 214B contain nanocarbon of the same conductivity type, the Seebeck coefficients of the two conductive wires 214A and 214B can be made different by changing either the type and amount of nanocarbon, or the type and amount of dopant used to dope the nanocarbon. The combination of the two conductive wires 214A and 214B is the same as the combination of the two conductive wires 114A and 114B in the first embodiment.

[0035] In the detection element 210, the two conductive wires 214A and 214B are applied as a woven or knitted body in which conductive wires such as nanocarbon yarn are braided or woven, for example. The two conductive wires 214A and 214B may be the same type of conductive wire or may be different types of conductive wires.

[0036] Details of the two conductive wires, 214A and 214B, will be described later.

[0037] The detection portion 216 of the detection element 210 is composed of a stitched portion 218 of a pair of conductive wires 212, each consisting of two conductive wires 214A and 214B. Specifically, for example, one end of a knitted or woven body in which two conductive wires 214A and 214B are braided or woven is stitched together, and this stitched portion 218 constitutes the detection portion 216 of the detection element 210.

[0038] The seam 218 can be exemplified by a seam formed by sewing together two knitted or woven bodies, each containing two conductive wires 214A and 214B, with a sewing material. Examples of sewing materials include nanocarbon yarn, nanocarbon ribbon, yarn or ribbon made from natural fibers (silk, cotton, etc.), yarn or ribbon made from chemical fibers (polyester fiber, nylon fiber, etc.), and blended yarns of natural and chemical fibers.

[0039] The seam 218 can also be exemplified by a seam in which one conductive wire 214A is woven or knitted into a woven fabric, and the other conductive wire 214B is sewn into that fabric.

[0040] Here, examples of sewing methods include well-known stitches such as running stitch, basting stitch, backstitch, double backstitch, and overcast stitch.

[0041] Figure 3 shows an example in which the detection part 216 of the detection element 210 is formed by a seam 218, which is created by sewing together two knitted bodies, in which two conductive wires 214A and 214B are braided or woven, with a sewing material. Here, in Figure 3, 218A represents the sewing material.

[0042] (Third embodiment) As shown in Figure 4, the detection element 310 according to the third embodiment has a pair of conductive wires 312. The pair of conductive wires 312 consists of two conductive wires 314A and 314B that contain different types of conductive nanocarbon or the same type of conductive nanocarbon and have different Seebeck coefficients. When two conductive wires 314A and 314B contain nanocarbon of the same conductivity type, the Seebeck coefficients of the two conductive wires 314A and 314B can be made different by changing either the type and amount of nanocarbon, or the type and amount of dopant used to dope the nanocarbon. The combination of the two conductive wires 314A and 314B is the same as the combination of the two conductive wires 114A and 114B in the first embodiment.

[0043] In the detection element 310, the two conductive wires 314A and 314B are, for example, each made of a conductive wire such as nanocarbon yarn. The two conductive wires 314A and 314B may be the same type of conductive wire or different types of conductive wire.

[0044] Details of the two conductive wires 314A and 314B will be described later.

[0045] The detection portion 316 of the detection element 310 is composed of a twisted portion 318 of a pair of conductive wires 312, which consist of two conductive wires 314A and 314B. Specifically, one end of the two conductive wires 314A and 314B are twisted together, and this twisted portion 318 constitutes the detection portion 316 of the detection element 310. Alternatively, the entire two conductive wires 314A and 314B may be twisted together.

[0046] The twisted portion 318 can be exemplified by a twisted portion formed by bundling one end of two conductive wires 314A and 314B together and twisting the bundled portion so that the ends of the conductive wires 314A and 314B wrap around each other.

[0047] (Fourth embodiment) The detection element 410 according to the fourth embodiment has a pair of conductive wires 412, as shown in Figure 5. The pair of conductive wires 412 consists of two conductive wires 414A and 414B that contain nanocarbons of different conductivity types or the same conductivity type, and have different Seebeck coefficients. When two conductive wires 414A and 414B contain nanocarbon of the same conductivity type, the Seebeck coefficients of the two conductive wires 414A and 414B can be made different by changing either the type and amount of nanocarbon, or the type and amount of dopant used to dope the nanocarbon. The combination of the two conductive wires 414A and 414B is the same as the combination of the two conductive wires 114A and 114B in the first embodiment.

[0048] In the detection element 410, the two conductive wires 414A and 414B are, for example, each made of a conductive wire such as nanocarbon yarn. The two conductive wires 414A and 414B may be the same type of conductive wire or different types of conductive wire.

[0049] Details of the two conductive wires 414A and 414B will be described later.

[0050] The detection portion 416 of the detection element 410 is composed of a braided portion 418 of a pair of conductive wires 412, consisting of two conductive wires 414A and 414B. Specifically, one end of the two conductive wires 414A and 414B are braided or woven together, and this braided portion 418 constitutes the detection portion 416 of the detection element 410. Alternatively, the entirety of the two conductive wires 414A and 414B may be braided or woven together.

[0051] The knitted section 418 can be exemplified by a knitted section in which two conductive wires 414A and 414B are knitted using well-known knitting methods such as plain knit, jersey knit, or stockinette knit. The woven section 418 can be exemplified by a section in which two conductive wires 414A and 414B are woven using a well-known weaving method such as plain weave, twill weave, or satin weave.

[0052] (Fifth embodiment) As shown in Figure 6, the detection element 510 according to the fifth embodiment has, for example, a pair of conductive wires 512. The pair of conductive wires 512 consists of one conductive wire 514 having two regions 514A and 514B with different Seebeck coefficients, each containing nanocarbon of different conductivity types or the same conductivity type. When two regions 514A and 514B of a single conductive wire 514 contain nanocarbon of the same conductivity type, the Seebeck coefficients of the two regions 514A and 514B of a single conductive wire 514 can be made different by changing either the type and amount of nanocarbon or the type and amount of dopant used to dope the nanocarbon in the two regions 514A and 514B.

[0053] The combinations of two regions 514A and 514B in a single conductive wire 514 are as follows: 1) A combination of a P-type region 514A containing P-type nanocarbon that is either undoped or doped with a P-type dopant, and an N-type region 514B containing N-type nanocarbon that is doped with an N-type dopant. 2) A combination of a P-type region 514A containing P-type nanocarbons that are either undoped or doped with a P-type dopant, and a P-type region 514B containing P-type nanocarbons that are doped with more P-type dopant than the P-type nanocarbons contained in P-type region 514A. 5) A combination of an N-type region 514A containing N-type nanocarbons doped with an N-type dopant, and an N-type region 514B containing N-type nanocarbons that are doped with more N-type dopant than the N-type nanocarbons contained in N-type region 514A.

[0054] Among these combinations, the combination of P-type region 514A and P-type region 514B is preferred because it is less prone to deterioration of carrier characteristics and has high durability. In other words, it is preferable that the same conductive nanocarbon is P-type nanocarbon.

[0055] In the detection element 510, one of the conductive wires 514 is, for example, a conductive wire such as nanocarbon yarn. Further details about one of the conductive wires 514 will be described later.

[0056] The detection portion 516 of the detection element 510 is composed of the boundary portion 518 of two regions 514A and 514B with different Seebeck coefficients in a single conductive wire 514. Specifically, for example, the conductive wire 514 is bent or curved starting from the boundary portion 518, and the part with the highest curvature is designated as the boundary portion 518, and this boundary portion 518 is designated as the detection portion 516 of the detection element 510.

[0057] (Other embodiments) In the first to fifth embodiments described above, the detection units 116, 216, 316, 416, and 516 of each detection element 110, 210, 310, 410, and 510 were described in an unsupported state, but they may also be provided in a state supported by other members. Examples of configurations in which the detection units 116, 216, 316, 416, and 516 are supported by other members include configurations in which each conductive wire of a pair of conductive wires is provided on a flexible substrate, and configurations in which they are sewn into a cloth substrate.

[0058] In the first to fifth embodiments described above, each detection element 110, 210, 310, 410, and 510 may have one or more other conductive wires having the same carrier characteristics, in addition to the two conductive wires or one conductive wire that constitute a pair of conductive wires. In other words, each of the two conductive wires constituting a pair of conductive wires, and each conductive wire itself, may be present in multiples and bundled together. This improves thermal conductivity and the signal-to-noise ratio (S / N) (i.e., noise). As a result, the response speed is further improved.

[0059] <Conductive wire> The details of the conductive wires applied to the detection elements 110, 210, 310, 410, and 510 according to the first to third embodiments will be described below. Reference numerals will be omitted in the description.

[0060] The conductive wire contains nanocarbon. For example, if we take single-walled carbon nanotubes as the nanocarbon, it is preferable from the viewpoint of conductivity and durability that the nanocarbon content in the conductive wire be 0.2% by mass or more. In particular, the conductive wire is preferably a conductive wire that contains nanocarbon as its main component. Specifically, the conductive wire is preferably a conductive wire that contains nanocarbon in an amount of 50% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more, and ideally 100% by mass.

[0061] Examples of conductive wires include nanocarbon yarns and other conductive wires with a diameter of 50 to 500 μm. The conductive wire may also be covered with an insulating resin coating layer. Examples of well-known insulating resins for the insulating resin coating layer include polyethylene, polyolefins (polyethylene, polypropylene, etc.), polystyrene, poly(meth)acrylic acid esters, styrene-(meth)acrylic acid ester copolymers, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, straight silicone resin or its modified products, fluororesin, polycarbonate, phenolic resin, epoxy resin, and polyurethane resin.

[0062] (Nanocarbon) Carbon nanotubes (CNTs) are preferred as the nanocarbons that make up the conductive wires. Carbon nanotubes are preferred because they have a high thermoelectric power and are easily formed into wires. Carbon nanotubes may be single-walled carbon nanotubes (SWCNTs) in which a single carbon film (graphene sheet) is wound into a cylindrical shape. Carbon nanotubes may also be multi-walled carbon nanotubes (MWCNTs), such as double-walled, triple-walled, or quadruple-walled carbon nanotubes, in which two graphene sheets are wound concentrically. Considering thermoelectric properties, carbon nanotubes with 10 layers or less are preferable. Single-walled carbon nanotubes are preferable because they easily provide high thermoelectric properties. Multi-walled carbon nanotubes are preferable because they are inexpensive and easy to mass-produce. Single-walled and multi-walled carbon nanotubes can also be used in combination. Furthermore, carbon nanotubes may be metallic carbon nanotubes, semiconducting carbon nanotubes, or a mixture of both. The method for producing carbon nanotubes is not particularly limited. Carbon nanotubes can be produced by methods such as arc discharge, chemical vapor deposition (CVD), and laser ablation. Commercially available carbon nanotubes may also be used.

[0063] Nanocarbon may also be graphene. By inserting carriers between two layers of graphene, graphene can be used as a semiconductor material.

[0064] Other examples of nanocarbons include carbon nanorods, carbon nanowires, graphene, and fullerenes.

[0065] --Type P Dopant-- P-type dopants that can be doped into nanocarbons refer to dopants whose Seebeck coefficient in the doped nanocarbon is a positive value, and include nonionic compounds or ionic compounds. P-type dopants are preferable to N-type dopants in terms of durability. In particular, when the solvent for the P-type dopant solution used for doping is water, a nonionic compound is preferred as the P-type dopant. On the other hand, when the solvent of the P-type dopant solution for doping is an organic solvent, an ionic compound is preferable as the P-type dopant.

[0066] Examples of non-ionic compounds that are P-type dopants include tetracyanoquinodimethane (TCNQ) derivatives (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, 2,5-dimethyl-7,7,8,8-tetracyanoquinodimethane, 2-fluoro-7,7,8,8-tetracyanoquinodimethane, 2,5-difluoro-7,7,8,8-tetracyanoquinodimethane, etc.), benzoquinone derivatives (2,3-dichloro-5,6-dicyano-p-benzoquinone, tetrafluoro-1,4-benzoquinone, etc.) quinosaline derivatives (5,8H-5,8-bis(dicyanomethylene)quinoxaline, dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile, etc.), 9H-carbazole, 9H-carbazol-4-ol, pyrazine and the like.

[0067] Examples of ionic compounds that are P-type dopants include perchlorate ion (ClO 4- ), permanganate ion (MnO 4- ), iodate ion (IO 3- ), thiocyanate ion (SCN - ), hexafluorophosphate ion (PF 6- ), tetrafluoroborate ion (BF 4- ), trifluoromethanesulfonate anion (TfO - ), bis(trifluoromethanesulfonyl)amine anion (TFSI - ), iodide ion (I - ), bromide ion (Br - ), chloride ion (Cl - ), nitrate ion (NO 3- ) or tosylate ion (Tos - ), including hydracids and metal salts thereof. Examples of metal salts include silver salts and copper salts.

[0068] --Type N Dopant-- N-type dopants that can be used to dope nanocarbons refer to dopants that result in a negative Seebeck coefficient in the doped nanocarbons, and include nonionic compounds or ionic compounds. In particular, when the solvent for the N-type dopant solution used for doping is water, a nonionic compound is preferred as the N-type dopant. On the other hand, when the solvent for the N-type dopant solution used for doping is an organic solvent, an ionic compound is preferred as the N-type dopant.

[0069] As the nonionic compound that acts as the N-type dopant, polyalkyleneimines are preferred. As the polyalkylene imine, polyalkylene imines having constituent units with alkylene groups having 1 to 6 carbon atoms (preferably 1 to 4 carbon atoms, more preferably 1 to 2 carbon atoms) are preferred, and polyethyleneimine is more preferred.

[0070] Examples of ionic compounds that act as N-type dopants include alkali metal salts (salts of lithium, sodium, potassium, or cesium, etc.) and alkylammonium salts (salts of tetraethylammonium ions, tetrabutylammonium ions, etc.). Among these, alkylammonium halides are preferred as ionic compounds, and the following compounds are examples.

[0071] [ka]

[0072] Examples of N-type dopants include complexes of alkali metal salts and cyclic ethylene oxides. Ions found in alkali metal salts include hydroxyl ions (OH) - ), alkoxy ions (CH3O- CH3CH2O - i-PrO - and t-BuO - (etc.), thioions (SH) - and alkylthioions (CH3S - and C2H5S - etc.), cyanuryl ions (CN - ), carboxyl ion (CH3COO - Examples include: Examples of alkali metals contained in alkali metal salts include lithium, sodium, and potassium. Examples of cyclic ethylene oxides include crown ethers.

[0073] Examples of N-type dopants include phosphine compounds such as triphenylphosphine, trioctylphosphine, and 1,3-bis(diphenylphosphine)propane.

[0074] --doping-- One method for doping a conductive wire (or a portion of a conductive wire) containing nanocarbon with a dopant is to immerse the heated conductive wire (or a portion of a conductive wire) in a dopant solution. This method allows for simple and low-cost doping. After doping, the wire is washed. However, doping with a dopant may be performed by methods such as application or brushing.

[0075] From the viewpoint of reducing environmental impact, the solvent of the dopant solution preferably contains water as its main component. The solvent containing water as its main component may also contain water-soluble organic solvents such as alcohols (methanol, ethanol, propanol, etc.). Note that "water as the main component" means, for example, that the proportion of water is 50% by mass (preferably 70% by mass, or 90% by mass) or more of the total solvent. However, the solvent of the dopant solution may have an organic solvent as its main component. Examples of organic solvents include alcohols (ethanol, propanol, etc.), acetone, methyl ethyl ketone, and butyl acetate. Having an organic solvent as the main component means, for example, that the proportion of the organic solvent is 50% by mass (preferably 70% by mass, or 90% by mass) or more of the total solvent. [Examples]

[0076] Examples are described below, but this disclosure is not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" all refer to mass.

[0077] <Example 1> Undoped carbon nanotube yarn with a diameter of approximately 100 μm, with a Seebeck coefficient of approximately 50 μVK. -1 It was prepared as a P-type carbon nanotube yarn. On the other hand, a carbon nanotube yarn with a diameter of approximately 100 μm and an N-type dopant solution (solute: triphenylphosphine, solvent: acetone, concentration: approximately 1 mol / L) were prepared. The carbon nanotube yarn was immersed in the N-type dopant solution and left for more than 24 hours. The carbon nanotube yarn was removed from the N-type dopant solution and washed with acetone. As a result, the entire yarn became an N-type conductive region with a Seebeck coefficient of -55 μVK. -1 We obtained N-type carbon nanotube yarn. The obtained N-type carbon nanotube yarn and P-type carbon nanotube yarn were joined at one end to form a pair of conductive wires. The entire pair of conductive wires obtained was fixed to a quartz glass support using carbon epoxy to obtain a detection element. The response speed of the obtained detection element was investigated by switching light from a terahertz (THz) wave source on and off, and examining its switching characteristics. The results are shown in Figure 1. Furthermore, an investigation into the time constant of the voltage change of the detection element revealed that the response speed of the detection element was 3.5 s. In addition, based on the magnitude of the voltage change under terahertz (THz) wave irradiation and non-irradiation conditions, the signal-to-noise ratio (S / N ratio) was approximately 5.2.

[0078] <Example 2> In Example 1, only the ends of the pair of conductive wires obtained were fixed to a quartz glass support using carbon epoxy to obtain a detection element. In this way, the detection element was in an unsupported state. The response speed of the obtained detection element was investigated by switching light from a terahertz (THz) wave source on and off and examining its switching characteristics. Furthermore, an investigation of the time constant of the voltage change of the detection element revealed that the response speed of the detection element was 11.8 s. In addition, the signal-to-noise ratio (S / N ratio) was approximately 10.9, which is an improvement in sensitivity compared to the S / N ratio of approximately 5.2 of the detection element in Example 1, where the detection unit was supported by a support.

[0079] <Example 3> In the same manner as in Example 1, two N-type carbon nanotubes and two P-type carbon nanotube yarns were prepared. Two bundles of N-type carbon nanotubes and two bundles of P-type carbon nanotube yarns were connected at one end to form a pair of conductive wires. The ends of the pair of conductive wires obtained were fixed to a quartz glass support using carbon epoxy to obtain a detection element. In this way, the detection part was configured as a detection element in an unsupported state. The response speed of the obtained detection element was investigated by switching light from a terahertz (THz) wave source on and off and examining its switching characteristics. The response speed of the detection element was 4.53 s. The signal-to-noise ratio (S / N ratio) was approximately 81.6, which is an improvement in sensitivity compared to the S / N ratio of the detection element in Example 1. In this case, the magnitude of the noise equivalent power (NEP) was 1.88 × 10⁻¹⁶. -10 W / Hz 1 / 2 Therefore, the typical NEP value of a detection element composed of a carbon nanotube monolayer film is ~100 × 10⁻⁶.-10 W / Hz 1 / 2 This demonstrates that terahertz wave measurements are possible with two orders of magnitude smaller sensitivity than (Erikson et al., ACS Nano 9, 11618 (2015)).

[0080] <Example 4> Undoped carbon nanotube yarn with a diameter of approximately 100 μm, with a Seebeck coefficient of approximately 50 μVK. -1 It was prepared as a P-type carbon nanotube yarn. Meanwhile, a carbon nanotube yarn with a diameter of approximately 100 μm and an N-type dopant solution (solute: triphenylphosphine, solvent: acetone, concentration: approximately 1 mol / L) were prepared. Half of the length of the prepared P-type carbon nanotube yarn was immersed in the N-type dopant solution and left for more than 24 hours. The carbon nanotube yarn was removed from the N-type dopant solution and washed with acetone. As a result, half of the length of the P-type carbon nanotube yarn became an N-type conductive region, with a Seebeck coefficient of approximately -55 μVK. -1 We obtained carbon nanotube yarn. In this process, a single conductive wire, containing both P-type and N-type regions within a carbon nanotube yarn, was fixed to a quartz glass support using carbon epoxy to obtain a detection element. The response speed of the obtained detection element was investigated by switching light from a terahertz (THz) wave source on and off, and examining its switching characteristics. The results are shown in Figure 4. The response of the detection element was then confirmed. The signal-to-noise ratio (S / N ratio) was approximately 1.26. In this case, the noise equivalent power (NEP) was estimated to be 4.83 × 10⁻¹⁶. -12 W / Hz 1 / 2 That was the case.

[0081] [Table 1]

[0082] From the above results, it can be seen that the detection element in this embodiment has a fast response speed and low noise. [Explanation of symbols]

[0083] 10 Electromagnetic wave detection device 12. Detection element for electromagnetic wave detection device 14 Amplifier 16 Digital Converters 18 Measuring Instruments 110, 210, 310, 410, 510 detection elements 112,212,312,412,412 pairs of conductive wires 114A,114B,214A,214B,314A,314B,414A,414B,514 Conductive wire

Claims

1. A detection element for an electromagnetic wave detection device having a pair of conductive wires, which detects electromagnetic waves ranging from infrared to microwave, The pair of conductive wires A pair of conductive wires consisting of two conductive wires containing different types of conductive nanocarbon and having different Seebeck coefficients. A pair of conductive wires consisting of two conductive wires containing the same conductive type of nanocarbon but with different Seebeck coefficients, or A pair of conductive wires, each consisting of a single conductive wire containing nanocarbons of different conductivity types or the same conductivity type, and having two regions with different Seebeck coefficients. A detection element for an electromagnetic wave detection device.

2. The detection element for an electromagnetic wave detection device according to claim 1, wherein the aforementioned nanocarbon of the same conductive type is P-type nanocarbon.

3. The detection element for an electromagnetic wave detection device according to claim 1, wherein the nanocarbon is a carbon nanotube.

4. The detection element for an electromagnetic wave detection device according to claim 1, wherein the detection portion of the detection element is in an unsupported state.

5. The detection element for an electromagnetic wave detection device according to claim 1, wherein each of the two conductive wires and the single conductive wire are multiple and bundled together.

6. A detection element for an electromagnetic wave detection device having a pair of conductive wires, which detects electromagnetic waves ranging from infrared to microwave, The detection unit of the detection element, The joint between a pair of conductive wires, each consisting of two conductive wires containing different types of nanocarbon or the same type of nanocarbon, and having different Seebeck coefficients. A joint between two conductive wires, each containing nanocarbon of different conductivity types or the same conductivity type, and having different Seebeck coefficients. A twisted portion of a pair of conductive wires consisting of two conductive wires containing different types of conductive nanocarbon or the same type of conductive nanocarbon, and having different Seebeck coefficients. A braided section of a pair of conductive wires consisting of two conductive wires containing different types of conductive nanocarbon or the same type of conductive nanocarbon, but with different Seebeck coefficients, or The boundary between two regions of a conductive wire having two regions with different Seebeck coefficients, containing nanocarbons of different conductivity types or the same conductivity type. A detection element for an electromagnetic wave detection device, comprising at least the following:

7. The detection element for an electromagnetic wave detection device according to claim 6, wherein the aforementioned nanocarbon of the same conductive type is P-type nanocarbon.

8. The detection element for an electromagnetic wave detection device according to claim 6, wherein the nanocarbon is a carbon nanotube.

9. The detection element for an electromagnetic wave detection device according to claim 6, wherein the detection portion of the detection element is in an unsupported state.

10. The detection element for an electromagnetic wave detection device according to claim 6, comprising each of the two conductive wires and a plurality of the single conductive wires bundled together.

11. The device comprises a detection element for an electromagnetic wave detection device according to any one of claims 1 to 10, An electromagnetic wave detection device that detects electromagnetic waves ranging from infrared to microwave.

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