JP2024032646A - Bolometer using carbon nano-tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-resistant bolometer and a method for manufacturing the bolometer.

SOLUTION: The present invention relates to a bolometer including two electrodes on a substrate and a bolometer film including a carbon nano-tube. The bolometer film is provided to connect regions of upper surfaces of the two electrodes, regions in contact with electrode walls of the two electrodes, and a region between the two electrodes on the substrate. Area density of the regions in contact with the electrode walls of the bolometer film is equal to area density of the region between the electrodes on the substrate at the most, or a film thickness of the regions in contact with the electrode walls of the bolometer film is equal to a film thickness of the region between the electrodes on the substrate at the most.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a bolometer using carbon nanotubes and a method for manufacturing the same.

Infrared sensors have a wide range of applications, including not only security surveillance cameras, but also human body thermography, vehicle-mounted cameras, and inspections of structures, food, etc., and their industrial applications have become active in recent years. ing. In particular, the development of inexpensive and high-performance uncooled infrared sensors that can acquire biological information through cooperation with IoT (Internet of Things) is expected. Conventional uncooled infrared sensors mainly use VO _x (vanadium oxide) in the bolometer part, but this requires heat treatment under vacuum, which increases the process cost and reduces the temperature coefficient of resistance. (TCR: Temperature Coefficient Resistance) is small (approximately -2.0%/K).

To improve TCR, it is necessary to use a material that has a large resistance change with temperature changes and high conductivity, so semiconducting single-walled carbon nanotubes with a large band gap and carrier mobility are used in the bolometer part. is expected. Additionally, because carbon nanotubes are chemically stable, inexpensive device fabrication processes such as printing technology can be applied to them, making it possible to create low-cost, high-performance infrared sensors.

For example, in Patent Document 1, ordinary single-walled carbon nanotubes are applied to the bolometer part, and the chemical stability of the single-walled carbon nanotubes is utilized to prepare a dispersion liquid mixed in an organic solvent, which is then placed on the electrode. It has been proposed to fabricate a bolometer using an inexpensive thin film coating process. At that time, by annealing the single-walled carbon nanotubes in air, they succeeded in improving the TCR to approximately -1.8%/K.

Single-walled carbon nanotubes usually contain semiconductor-type carbon nanotubes and metallic-type carbon nanotubes in a ratio of 2:1, so there is a problem in that they must be separated. Therefore, in Patent Document 2, since single-walled carbon nanotubes contain a mixture of metallic and semiconducting components, semiconducting single-walled carbon nanotubes with uniform chirality are extracted using an ionic surfactant, and the bolometer portion is By applying this method to , we succeeded in realizing a TCR of -2.6%/K.

WO2012/049801 Japanese Patent Application Publication No. 2015-49207

However, in order to put an infrared sensor using carbon nanotubes (CNT uncooled infrared sensor) into practical use, it is necessary to improve characteristics such as lower resistance in addition to improving TCR.
For example, the bolometer part of a CNT uncooled infrared sensor has a structure in which the electrodes are connected by a bolometer film containing carbon nanotubes, so how the carbon nanotubes are bonded to the electrodes affects the resistance. However, with the conventional method of forming a bolometer film in a bolometer, it is sometimes difficult to reduce the resistance.
Therefore, an object of the present invention is to provide a bolometer that can reduce resistance and a method for manufacturing the same.

One aspect of the present invention is
A bolometer comprising two electrodes provided on a substrate and a bolometer film containing carbon nanotubes,
The bolometer film is provided to connect the upper surface area of the two electrodes, the area in contact with the electrode wall of the two electrodes, and the area between the two electrodes on the substrate,
The area density of the region of the bolometer film in contact with the electrode wall is less than or equal to the area density of the region between the electrodes on the substrate, or the film thickness of the region of the bolometer film in contact with the electrode wall is less than or equal to the film thickness of the region between the electrodes on the substrate. Something about bolometers.

Further, another aspect of the present invention is
A method for manufacturing a bolometer comprising two electrodes provided on a substrate and a bolometer film containing carbon nanotubes, the method comprising:
The substrate with electrodes formed on its surface is passed through the liquid surface of the carbon nanotube dispersion liquid at a movement speed/number of movements of 5 μm/sec or less. The present invention relates to a manufacturing method including a step of forming an electrode wall of two electrodes and a region between two electrodes on a substrate so as to connect them.

According to the present invention, it is possible to provide a bolometer that can reduce resistance and a method for manufacturing the same.

FIG. 1 is a schematic diagram (cross-sectional view) showing the structure of a bolometer according to an embodiment of the present invention. FIG. 1 is a schematic diagram (perspective view) showing the structure of a bolometer according to an embodiment of the present invention. FIG. 1 is a schematic diagram (cross-sectional view) showing the structure of a bolometer according to an embodiment of the present invention. FIG. 3 is a diagram (top view) showing the orientation direction of carbon nanotubes in the present invention. FIG. 3 is a diagram showing an example of a bolometer array according to an embodiment of the present invention. FIG. 1 is a schematic diagram showing one step in a method for manufacturing a bolometer according to an embodiment of the present invention. It is a SEM image of the bolometer film in an example. It is a SEM image of the bolometer film in an example. This is an image obtained by subjecting a SEM image of a bolometer film in an example to two-dimensional fast Fourier transform processing. It is a SEM image of the bolometer film in an example. It is a SEM image of the bolometer film in an example. It is a SEM image of the bolometer film in an example. FIG. 2 is a schematic diagram (cross-sectional view) showing the structure of a bolometer in a conventional example. It is a SEM image of a bolometer film in a conventional example.

FIG. 1 is a cross-sectional view of an example of the bolometer of this embodiment. The bolometer of this embodiment has a bolometer film (hereinafter referred to as "carbon nanotube film" or "carbon nanotube film" or " (also referred to as "CNT film") 3.

Carbon nanotubes of various lengths can be used as carbon nanotubes for the bolometer film depending on the purpose, but when short carbon nanotubes are used, the bolometer film is formed between the top surface of the two electrodes and the top surface of the two electrodes as shown in FIG. Formed in the area between two electrodes, the carbon nanotubes on the top surface of the electrodes are not connected to the bolometer film between the electrodes. Therefore, it has been found that there is a problem in that the carbon nanotubes on the upper surface of the electrode do not contribute as a component of the bolometer film. In addition, when attempting to fabricate a bolometer film spanning two electrodes, it was found that there was a problem in that agglomerated masses of carbon nanotubes were formed irregularly and partially on the electrodes, as shown in Figure 14. . Bolometers such as these have a problem in that they tend to have high resistance.

On the other hand, in the bolometer of the present embodiment, as shown in FIGS. 1 and 2, the bolometer film 3 has a region on the upper surface of the two electrodes 2 and 4 (also referred to as "region A"), a region on the upper surface of the two electrodes 2 and 4, It is formed to connect a region in contact with the electrode wall (also referred to as "region B") and a region sandwiched between two electrodes on the substrate (also referred to as "region C").
Further, the bolometer of this embodiment has a feature that the areal density of region B is less than or equal to the areal density of region C, or that the film thickness of region B is less than or equal to the film thickness of region C.
With such a configuration, the resistance of the bolometer can be reduced.

[Structure of bolometer]
Each component of the bolometer of this embodiment will be explained in detail.

1. Substrate As the substrate, those used for bolometers can be used without particular limitation.
The substrate may be either a flexible substrate or a rigid substrate, and can be selected as appropriate, but it is preferable that at least the surface on which the elements are formed is insulating or semiconducting. For example, inorganic materials such as Si, SiO ₂ coated Si, SiO ₂ , SiN, and glass, and organic materials such as polymers, resins, and plastics, such as parylene, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene. Terephthalate, acrylonitrile styrene resin, acrylonitrile butadiene styrene resin, fluororesin, methacrylic resin, polycarbonate, etc. can be used, but are not limited to these.

An intermediate layer that enhances the adhesiveness between the substrate and the carbon nanotubes may be provided at a portion of the substrate surface where the carbon nanotubes are bonded. The intermediate layer is not particularly limited as long as it is a layer made of a material that enhances the bond between the substrate and carbon nanotubes.
The material of the intermediate layer is preferably a compound having both a partial structure that is bonded to or attached to the substrate surface and a partial structure that is bonded to or attached to the carbon nanotubes. Thereby, the intermediate layer functions as an intermediary for bonding the substrate and carbon nanotubes. Here, the bond between the substrate and the intermediate layer and the bond between the intermediate layer and the carbon nanotubes are not only chemical bonds, but also electrostatic interactions, surface adsorption, hydrophobic interactions, van der Waals forces, Various intermolecular interactions such as hydrogen bonds can be used. It is also preferred that the material of the intermediate layer is a compound that increases the lyophilicity of the substrate surface.

Examples of the partial structure in the intermediate layer material that is bonded or attached to the substrate surface include an alkoxysilyl group (SiOR), SiOH, a hydrophobic portion, or a hydrophobic group. Examples of the hydrophobic moiety or hydrophobic group include a methylene group (methylene chain) and an alkyl group having 1 or more carbon atoms, preferably 2 or more carbon atoms, and preferably 20 or less carbon atoms, more preferably 10 or less carbon atoms.
Examples of partial structures bonded to or attached to carbon nanotubes in the intermediate layer material include primary amino groups (-NH ₂ ), secondary amino groups (-NHR ₁ ), and tertiary amino groups (-NR _{1 )} . R ₂ ), ammonium group (-NH ₄ ), imino group (=NH), imido group (-C(=O)-NH-C(=O)-), amide group (-C(= O)NH-), epoxy group, isocyanurate group, isocyanate group, ureido group, sulfide group, mercapto group and the like.

The material for such an intermediate layer is not particularly limited, but includes, for example, a silane coupling agent. The silane coupling agent has in its molecule both a reactive group that binds to or interacts with an inorganic material and a reactive group that binds to or interacts with an organic material, and has the function of binding the organic material and the inorganic material. In this embodiment, for example, a silane coupling agent having both a reactive group that binds to a substrate such as a Si substrate and a reactive group that binds to carbon nanotubes is used to present a reactive group that binds to carbon nanotubes on the substrate. By forming a single-layer multilayer film, carbon nanotubes can be fixed on a substrate.

Examples of silane coupling agents include:
3-aminopropyltrimethoxysilane, 3-aminopropylmethyltriethoxysilane, 3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane (APTES), 3-(2-aminoethyl)aminopropyltrimethoxysilane , N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyl A silane coupling agent (aminosilane compound) having an amino group and an alkoxysilyl group such as dimethoxysilane;
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl) ) A silane coupling agent having an epoxy group and an alkoxysilyl group such as ethyltrimethoxysilane, 3-glycidoxypropyldiethoxysilane, triethoxy(3-glycidyloxypropyl)silane;
Isocyanurate-based silane coupling agents such as tris-(trimethoxysilylpropyl) isocyanurate;
A ureido-based silane coupling agent such as 3-ureidopropyltrialkoxysilane;
Mercapto-based silane coupling agents such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane;
Sulfide-based silane coupling agents such as bis(triethoxysilylpropyl)tetrasulfide; and isocyanate-based silane coupling agents such as 3-isocyanatepropyltriethoxysilane;
Examples include.

In particular, a silane coupling agent having an amino group (aminosilane compound) is preferred because it has good bonding properties with carbon nanotubes.

Note that in this specification, the term "substrate" refers to any base material on which the bolometer film and electrodes of this embodiment are formed and supports the bolometer film and electrodes. The "substrate" is not limited to a flat base material such as a glass plate or a silicon wafer, and may have a structure or a multilayer structure. Therefore, the bolometer of this embodiment is not limited to the forms shown in FIGS. 1 and 2, but can also be applied to a bolometer having a diaphragm structure or a bolometer having an arbitrary layer such as a heat insulating layer below the bolometer film. For example, in the case of a bolometer having a diaphragm structure, a diaphragm having a gap as a heat insulating structure is provided, and the bolometer film and electrode of this embodiment are provided on top of the diaphragm. The entire material can be considered a "substrate." In addition, in the case of a bolometer having a heat insulating layer below the bolometer film, the heat insulating layer and other layers that may be formed thereon as necessary can be considered as a "substrate", and the present embodiment A bolometer membrane and electrodes will be provided.

2. Electrode Any electrode used in a bolometer can be used without particular limitation.
The material of the electrode is not particularly limited as long as it is conductive, but gold, platinum, titanium, copper, cobalt, nickel, carbon, palladium, iron, aluminum, silver, tungsten, zinc, chromium, tin, lead, magnesium, Single substances such as manganese, yttrium, niobium, vanadium, zirconium, molybdenum, indium, lanthanum, tantalum, hafnium, bismuth, ruthenium, and rhodium, and alloys containing them can be used alone or in combination.
The thickness of the electrode can be adjusted as appropriate, but is preferably 10 nm to 1 mm, more preferably 50 nm to 1 μm.
The distance between the two electrodes is preferably 1 μm to 500 μm, and more preferably 5 to 200 μm for miniaturization. If the thickness is 5 μm or more, for example, even if a small amount of metallic carbon nanotubes is included, deterioration in TCR characteristics can be suppressed. Further, if the thickness is 500 μm or less, it is advantageous for application to an image sensor formed into a two-dimensional array.

3. Bolometer Film As explained above, the bolometer film (carbon nanotube film) of the bolometer of this embodiment has a region on the upper surface of the two electrodes 2 and 4 (region A), a region in contact with the electrode walls of the two electrodes (region B ), and a region (region C) sandwiched between the two electrodes on the substrate. In this way, the carbon nanotubes in region A and the carbon nanotubes in region C are connected via the carbon nanotubes in region B, so that the carbon nanotubes in regions A and B can be used as components of the bolometer film. It becomes like this. This increases the contact area between the electrode and the carbon nanotube, making it possible to lower the resistance of the bolometer.
Note that the bolometer film may be one carbon nanotube layer, or may include two or more carbon nanotube layers. When the bolometer film includes two or more carbon nanotube layers, if at least one layer is formed so as to connect regions A, B, and C, the effect of lowering the resistance can be obtained.

Furthermore, in the bolometer of this embodiment, the areal density of the bolometer film in region B is less than or equal to the areal density of the bolometer film in region C, or the film thickness of the bolometer film in region B is less than or equal to the film thickness of the bolometer film in region C. It has the following characteristics.
In this embodiment, whether the areal density of the bolometer film in region B is less than or equal to the areal density of the bolometer film in region C, or whether the film thickness of the bolometer film in region B is less than or equal to the film thickness of the bolometer film in region C. , or both the areal density and film thickness of the bolometer film in region B may be less than or equal to the areal density and film thickness of the bolometer film in region C, respectively. In this specification, these may be collectively described as "the areal density and/or film thickness of the bolometer film in region B is equal to or less than the areal density and/or film thickness of the bolometer film in region C."
With such a configuration, further reduction in resistance can be achieved. The reason for this is not clear, but the resistance of a bolometer is greatly influenced by the contact state between the bolometer film and the electrode. This is thought to be because by suppressing the increase, the influence of impurities remaining in the bolometer film, for example, the residual surfactant described below, can be reduced, and thereby the contact state between the electrode and the bolometer film can be improved.
The film thickness and/or areal density of the bolometer film in region B is preferably 95% or less, and preferably 90% or less, of the film thickness and/or areal density of the bolometer film in region C, each independently. More preferred. Although the lower limit is not particularly limited, it is preferably 30% or more, more preferably 50% or more.
Furthermore, when the bolometer film is composed of two or more layers, such as when it includes an alignment layer to be described later, the upper layer may be mainly formed to connect region A, region B, and region C. The lower layer may be formed to connect Area A, Area B, and Area C as described above, but it is not necessarily connected and may be formed in Area A and Area C, or mainly in Area C. By connecting the lower layer to the electrodes in areas A and B, and connecting the upper layer to the lower layer in area C, it is possible to achieve low resistance. In this case, even if the upper layer is formed in the same way in area A, area B, and area C, only the upper layer exists in area B and there is almost no lower layer, or in area B Since there is a lower layer in which the film thickness and areal density are smaller than those in region C, the film thickness and/or areal density of the entire bolometer film in region B are different from the film thickness and/or areal density of the entire bolometer film in region C. Or, it has the characteristic of being less than or equal to the areal density. In particular, when the lower layer is mainly formed only in region C and is almost absent in region B, the film thickness and/or areal density of the bolometer in region B may be different from the film thickness and/or area density of the bolometer in region C. It can be much smaller than the areal density (Figure 11). In this case, the lower limit of the ratio of the film thickness and areal density of region B to region C is not particularly limited, but from the viewpoint of lowering the resistance, it is preferably 2% or more, and 5% or more. It is more preferable that there be.

In this specification, values measured in the central region of each region can be used as the film thickness and area density values of each region of the bolometer film.
Region b, where the film thickness and areal density of region B are measured, can be a 60% region at the center of region B. For example, in FIG. 3, when the height of the electrode is h, a range of 0.6h is centered around the center line of the height h, specifically, when the lower end of the electrode is 0h and the upper end is 1h, The range is from 0.2h to 0.8h. As described later, the areal density and film thickness of region b can be the average value of measured values measured at 10 random points included in the region.
Similarly, region c, in which the film thickness and areal density of region C are measured, can be set at 60% of the center of region C. For example, in FIG. 3, when the distance between the electrodes is w, the range of 0.6w is centered around the center line of the distance w, specifically, when the left end of the area between the electrodes is 0w and the right end is 1w. The range is 0.2w to 0.8w. The areal density and film thickness of region c can be the average value of measured values measured at 10 random points included in the region, as described later.

- Areal Density The areal density can be measured as the occupancy rate of carbon nanotubes in the regions b and c defined above. The carbon nanotube occupancy rate is determined by calculating the area occupied by carbon nanotubes and the area of the gap (area not occupied by carbon nanotubes) using image software at each measurement point, and calculating the carbon nanotube occupancy rate = It can be determined as: area occupied by carbon nanotubes/(area occupied by carbon nanotubes + area of gap). The image software is not particularly limited, but WinROOF or the like can be used. For example, the areal density is determined by calculating the carbon nanotube occupancy rate at 10 random measurement points (the area of each measurement point is 100 nm x 1 μm) in the SEM images of regions b and c, and then calculating the average value. You can ask for it.
Note that when the bolometer film contains a material other than carbon nanotubes, the area occupied by the other material is included in the area occupied by carbon nanotubes.

Furthermore, even when the bolometer film is composed of two or more layers, such as when it includes an alignment layer described below, the areal density refers to the areal density of the entire bolometer film having two or more layers. In the case of a bolometer film with two or more layers, if the upper layer is the only layer that connects region A, region B, and region C, the upper layer has a larger area than the lower layer. Since the density is small, the areal density of region B is clearly smaller than that of region C. In the case of two or more layers, the upper layer may or may not be oriented.

- Film Thickness The film thickness can be determined by measuring the film thickness at 10 random measurement points in each of the regions b and c defined above, and taking the average value thereof. The film thickness can be measured using a SEM image, a cross-sectional TEM, a laser microscope, or the like.
Note that when the bolometer film is composed of two or more layers, the film thickness means the total thickness of all the layers.

In one embodiment, the film thickness and/or areal density in the entire area A to C of the bolometer film are independently 1.2 times or less of the film thickness and/or areal density in area c, For example, the film thickness and/or areal density of region c or less. Depending on the method of manufacturing the bolometer film, pools of carbon nanotube dispersion may occur at the corners where the electrode and the substrate are in contact (at both ends of region C), and the bolometer film may become thick. On the other hand, in the manufacturing method of the present embodiment, which will be described later, such liquid pools are less likely to occur, so thick portions are less likely to occur in the bolometer film, and a uniform and low-resistance bolometer film can be manufactured.

The thickness of the bolometer film (herein referred to as the thickness of region C (region c)) is not particularly limited, but is, for example, 1 nm or more, for example, several nm to 100 μm, preferably 5 nm to 10 μm, more preferably 10 nm to 1 μm, More preferably, the range is from 15 nm to 500 nm, particularly preferably from 15 nm to 200 nm.
When the thickness of the bolometer film is 1 nm or more, good light absorption can be obtained.
Furthermore, if the thickness of the bolometer film is 10 nm or more, preferably 15 nm or more, sufficient light absorption can be obtained without providing a light reflection layer or a light absorption layer, so the device structure can be simplified. .
Further, it is preferable that the thickness of the bolometer film is 1 μm or less, preferably 500 nm or less, from the viewpoint of simplifying the manufacturing method.
In addition, when providing a light reflective layer or a light absorbing material layer, the thickness of the bolometer film may be made thinner than the above range to further simplify the manufacturing process and improve the resistance value.
When the bolometer film is composed of two or more layers, such as when it includes an alignment layer described below, it is preferable that the total thickness of all the layers is within the above range.

Further, the density of the bolometer film (in this specification, the density of region C (region c)) is, for example, 0.03 g/cm ³ or more, preferably 0.1 g/cm ³ or more, and more preferably 0.3 g/cm 3 or more. / ^cm3 or more. Although the upper limit is not particularly limited, it can be set to the upper limit of the true density of the carbon nanotubes used (for example, about 1.4 g/cm ³ ).
When the density of the bolometer film is 0.03 g/cm ³ or more, good light absorption can be obtained.
Furthermore, if the density of the bolometer film is 0.1 g/cm ³ or more, sufficient light absorption can be obtained without providing a light reflective layer or a light absorbing material layer, and the device structure can be simplified. It is preferable in that sense.
Note that when a light reflecting layer or a light absorbing material layer is provided, a lower density than the above may be appropriately selected as the density of the bolometer film.
When the bolometer film is composed of two or more layers, such as when it includes an alignment layer to be described later, it is preferable that the average density of all the layers is within the above range.

The density of the bolometer film can be calculated from the weight, area, and thickness of the bolometer film determined above.

As described above, the bolometer film of this embodiment may have one carbon nanotube layer, or may include two or more carbon nanotube layers.

When the bolometer film is composed of one carbon nanotube layer, the carbon nanotube layer may be a non-oriented layer or an oriented layer.

When the bolometer film includes two or more carbon nanotube layers, all the layers may be non-oriented layers, all the layers may be oriented layers, or a combination of non-oriented layers and oriented layers.
A preferred example of a bolometer film containing two or more carbon nanotube layers is one in which one layer is an orientation layer and the other layer is a layer in which, for example, carbon nanotubes are oriented in various directions to form a dense network-like structure. Another example is a bolometer film which is a non-oriented layer. By overlapping the oriented layer with the non-oriented layer, not only the contact area between the carbon nanotubes in the oriented layer increases, but also the carbon nanotubes in the oriented layer overlap with the dense carbon nanotubes in the non-oriented layer, which further increases the conductive path. increases and resistance decreases. This makes it possible to achieve low resistance and a large resistance change (high TCR) against temperature changes.
In another example, the bolometer film may be composed of two or more non-oriented layers. For example, carbon nanotubes in a non-oriented layer are provided to connect the upper surfaces of two electrodes, the electrode walls of the two electrodes, and the area between the two electrodes on the substrate in a dense carbon nanotube layer in the non-oriented layer. The effect of lowering resistance can also be obtained by overlapping layers.
Note that in this specification, the "alignment layer" refers to a layer in which at least some carbon nanotubes are oriented. The degree of orientation of the orientation layer will be described later. A "non-oriented layer" (non-oriented carbon nanotube layer) is a layer in which carbon nanotubes are oriented in different directions, preferably a layer in which carbon nanotubes are oriented in various directions to form a network-like structure. For example, it refers to a layer having an orientation degree fx/fy of less than 1.5, which will be described later.

In addition, when the bolometer film includes two or more carbon nanotube layers, "the bolometer film is provided so as to connect the upper surfaces of the two electrodes, the electrode walls of the two electrodes, and the area between the two electrodes on the substrate." The term ``contains'' only needs to mean that the bolometer film is formed so as to connect the above-mentioned regions as a whole. For example, all the layers constituting the bolometer film may be provided to connect the top surfaces of the two electrodes, the electrode walls of the two electrodes, and the area between the two electrodes on the substrate, or Only some of the layers are formed to connect the top surfaces of the two electrodes, the electrode walls of the two electrodes, and the area between the two electrodes on the substrate, so that the bolometer film as a whole is formed between the two electrodes. The upper surface of the electrode, the electrode walls of the two electrodes, and the area between the two electrodes on the substrate may be connected. When the bolometer film includes an alignment layer, from the viewpoint of reducing resistance, at least the alignment layer is provided so as to connect the upper surfaces of the two electrodes, the electrode walls of the two electrodes, and the region between the two electrodes on the substrate. It is preferable that

The degree of orientation of carbon nanotubes is measured in one direction from the center (one direction passing through the center) in a planar FFT image obtained by processing a SEM image of a carbon nanotube film by two-dimensional fast Fourier transform and expressing the distribution of unevenness in each direction as a frequency distribution. The integrated value f of the amplitude (intensity) from frequency -1 μm ^-1 to +1 μm ^-1 is calculated, the integrated value in the direction x where the integrated value f is maximum is fx, and the direction y perpendicular to the direction x is calculated. It can be defined by the value of fx/fy, where fy is the integrated value of fy. In the alignment layer of this embodiment, fx/fy≧1.5 is preferable, and fx/fy≧1.8 is more preferable. Note that the SEM image that is the source of the above FFT image needs to show irregularities in order to be calculated by Fourier transform, and from the perspective of observing carbon nanotubes, the viewing range is approximately 0.05 to 50 μm in both the vertical and horizontal directions. It is preferable to have one.
It is preferable that the degree of orientation in at least region C (region c) is within the above range.

The orientation direction of carbon nanotubes can be either parallel to the electrode (perpendicular to the direction of current flow (Figure 4, left)) or perpendicular to the electrode (parallel to the direction of current flow (Figure 4, right)). However, if the carbon nanotubes are not oriented perpendicular to the electrode (parallel to the direction in which the current flows), a higher resistance reduction effect can be obtained than when the carbon nanotubes are oriented parallel to the electrode. can.

The carbon nanotubes used in the bolometer film will be explained.
A carbon nanotube film (CNT film) as a bolometer film is a thin film mainly composed of a plurality of carbon nanotubes that form a conductive path that electrically connects two electrodes. For example, carbon nanotubes preferably have a network-like structure, and preferably form a three-dimensional network-like structure that is difficult to aggregate and provides a uniform conductive path. Further, it is more preferable that a layer having a structure in which carbon nanotubes are oriented is formed above or below the network structure of carbon nanotubes.

Single-walled, double-walled, and multi-walled carbon nanotubes can be used, but when separating semiconductor types, single-walled or several-walled (for example, two-walled or three-walled) carbon nanotubes are preferred; More preferred are layered carbon nanotubes. The carbon nanotubes preferably contain 80% by mass or more of single-walled carbon nanotubes, more preferably 90% by mass or more (including 100% by mass).

The bolometer film uses semiconducting carbon nanotubes, which have a large band gap and carrier mobility. The content of semiconducting carbon nanotubes, preferably semiconducting carbon nanotubes, is generally 67% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more of the total amount of carbon nanotubes. In particular, it is preferable that semiconducting carbon nanotubes be contained in a proportion of 90% by mass or more of the total amount of carbon nanotubes, more preferably 95% by mass or more, and even more preferably 99% by mass or more (including 100% by mass).

The diameter of the carbon nanotube is preferably between 0.6 and 1.5 nm, more preferably between 0.6 and 1.4 nm, and preferably between 0.7 and 1.2 nm, from the viewpoint of increasing the band gap and improving TCR. More preferred. Further, in one embodiment, a thickness of 1 nm or less may be particularly preferable. If the diameter is 0.6 nm or more, it is easier to manufacture carbon nanotubes. If it is 1.5 nm or less, it is easy to maintain the band gap within an appropriate range, and a high TCR can be obtained.

In this specification, the diameter of the carbon nanotube is determined by observing a carbon nanotube film using an atomic force microscope (AFM) and measuring the diameter at about 100 locations, and determining the diameter of the carbon nanotube by 60% or more, preferably 70% of the diameter. % or more, optionally preferably 80% or more, more preferably 100%, is within the range of 0.6 to 1.5 nm. Preferably, 60% or more, preferably 70% or more, optionally preferably 80% or more, more preferably 100% within the range of 0.6 to 1.4 nm, even more preferably 0.7 to 1.2 nm. within range. In one embodiment, 60% or more, preferably 70% or more, optionally preferably 80% or more, and more preferably 100% is within the range of 0.6 to 1 nm.

Further, the length of the carbon nanotubes is more preferably between 100 nm and 5 μm because they are easily dispersed and have excellent coating properties. Also, from the viewpoint of the conductivity of the carbon nanotube, it is preferable that the length is 100 nm or more. Further, if the thickness is 5 μm or less, aggregation during film formation can be easily suppressed. The length of the carbon nanotube is more preferably 300 nm to 4 μm, even more preferably 500 nm to 3 μm.
When the bolometer film is composed of two or more carbon nanotube layers, carbon nanotubes having a length within the above range are used for at least one carbon nanotube layer.

In this specification, the length of carbon nanotubes is determined by observing at least 100 carbon nanotubes using an atomic force microscope (AFM) and measuring the length distribution of carbon nanotubes by counting them. % or more, preferably 70% or more, optionally preferably 80% or more, and more preferably 100% is within the range of 100 nm to 5 μm. Preferably, 60% or more, preferably 70% or more, optionally preferably 80% or more, and more preferably 100% is within the range of 300 nm to 4 μm. More preferably, 60% or more, preferably 70% or more, optionally preferably 80% or more, and more preferably 100% is within the range of 500 nm to 3 μm.

When the diameter and length of the carbon nanotube are within the above range, the influence of semiconductor properties becomes large and a large current value can be obtained, so that a high TCR value is easily obtained when used as a bolometer film.

Further, in the bolometer film, in addition to the above-mentioned components, for example, ion conductive agents (surfactants, ammonium salts, inorganic salts), oxides, resins, organic binders, etc. may be used as appropriate.

The content of carbon nanotubes in the bolometer film can be selected as appropriate, but preferably 0.1% by mass or more is effective, more preferably 1% by mass or more based on the total mass of the bolometer film. For example, it is preferably 30% by mass, more preferably 50% by mass or more, and in some cases, 60% by mass or more is preferable.

5. Other Components The bolometer of this embodiment may include any component used in a bolometer in addition to the above.
For example, a protective film can be provided on the surface of the bolometer film if necessary. The protective film is preferably made of a material that is highly transparent in the light wavelength range that is desired to be detected. Examples of the material for the protective film include acrylic resins such as PMMA and PMMA anisole, epoxy resins, Teflon (registered trademark), silicon nitride, and silicon oxide (SiO ₂ ).
Furthermore, a light absorption structure such as a light absorption layer may be provided on the upper side of the bolometer film (on the side where light enters), if necessary. Examples of the light absorption layer provided on the protective layer include, for example, a thin film of titanium nitride, and examples of the light absorption layer provided on the bolometer film include, but are not limited to, a coating film of polyimide.

The bolometer of this embodiment detects temperature using the temperature dependence of electrical resistance due to light irradiation. The bolometer of this embodiment is preferably an infrared sensor. Furthermore, it can be used in a similar manner in frequency ranges other than infrared rays as long as the temperature changes due to light irradiation. The bolometer of this embodiment using a bolometer film containing carbon nanotubes can be particularly suitably used for detecting electromagnetic waves having a wavelength of 0.7 μm to 1 mm. Electromagnetic waves included in the wavelength range include infrared rays and terahertz waves.
Further, detection of changes in electrical resistance due to temperature changes can be performed not only by using the structure shown in FIG. 1, but also by amplifying changes in resistance by providing a field effect transistor with a gate electrode.
In addition, the bolometer of this embodiment has not only the structure shown in FIG. 1, but also an element having a diaphragm structure, an element having a desired heat insulating structure such as a heat insulating layer made of a heat insulating resin instead of the diaphragm structure, etc. The present invention can be applied to any element structure used in a bolometer without particular limitation.

Although the basic configuration of the bolometer of this embodiment has been shown above, any element structure and array structure that can be used for a bolometer can be applied to the bolometer of this embodiment without particular limitation. For example, the bolometer of this embodiment may be a single element, or may be an array of two-dimensional arrays of a plurality of elements, such as those used in image sensors.

[Manufacturing method of bolometer]
One aspect of the present invention relates to a method of manufacturing a bolometer.
According to the manufacturing method of this embodiment, as shown in FIGS. 1 and 2, region A on the upper surface of the electrode of the bolometer film and region C between the electrodes on the substrate are connected via region B in contact with the electrode wall. bolometers can be manufactured.
In one embodiment, according to the manufacturing method of the present embodiment, the areal density of the bolometer film in region B is equal to or lower than the areal density of the bolometer film in region C, or the film thickness of the bolometer film in region B is less than or equal to the areal density of the bolometer film in region C. A bolometer whose film thickness is equal to or less than that of the bolometer film can be manufactured.

1. Step of forming two electrodes on a substrate Two electrodes are formed on a substrate at a distance from each other.
Although the method for producing the electrode is not particularly limited, it can be formed by vapor deposition, sputtering, printing, pressing, or the like. Alternatively, it may be formed into a desired shape using a photomask, a metal mask, or the like. Alternatively, a pre-formed metal thin film or the like may be used.

Alternatively, as shown in FIG. 5, a plurality of electrode pairs may be formed side by side in the vertical and horizontal directions on the substrate to form an array.

In one embodiment, an intermediate layer may be formed on the substrate. Although a case where the intermediate layer is an APTES layer will be explained as an example, the intermediate layer is not limited to the APTES layer.
The intermediate layer can be formed by applying an APTES aqueous solution onto the substrate, washing with water, and drying if necessary.
The APTES solution may be applied by immersing the substrate in the APTES aqueous solution, or by spraying the APTES aqueous solution onto the substrate. Before applying the APTES aqueous solution, regions other than the region where the intermediate layer is to be formed may be protected with various mask materials.
The concentration of the APTES aqueous solution is preferably 0.001 volume% or more and 30 volume% or less, more preferably 0.01 volume% or more and 10 volume% or less, and even more preferably 0.05 volume% or more and 5 volume% or less. Naturally, when using a compound other than APTES as the intermediate layer, the concentration and solvent may be changed as appropriate depending on the compound used.

2. Step of Preparing Carbon Nanotube Dispersion In the manufacturing method of the present embodiment, it is preferable to use a carbon nanotube dispersion containing carbon nanotubes for producing the bolometer film.

The carbon nanotubes used in the carbon nanotube dispersion may be heat-treated in vacuum under an inert atmosphere to remove surface functional groups, impurities such as amorphous carbon, catalysts, and the like. The heat treatment temperature can be selected as appropriate, but is preferably 800-2000°C, more preferably 800-1200°C.

It is preferable to add a surfactant to the carbon nanotube dispersion.
The surfactant is preferably a nonionic surfactant because it can be easily removed. Nonionic surfactants can be selected as appropriate, but hydrophilic surfactants that do not ionize, such as nonionic surfactants with a polyethylene glycol structure such as polyoxyethylene alkyl ethers, and alkyl glucoside nonionic surfactants. It is preferable to use one or a combination of nonionic surfactants composed of a hydrophobic moiety and a hydrophobic moiety such as an alkyl chain. As such a nonionic surfactant, polyoxyethylene alkyl ether represented by formula (1) is preferably used. Further, the alkyl portion may contain one or more unsaturated bonds.

C _n H _2n+1 (OCH ₂ CH ₂ ) _m OH (1)
(In the formula, n = preferably 12 to 18, m = 10 to 100, preferably 20 to 100)

In particular, polyoxyethylene (23) lauryl ether, polyoxyethylene (20) cetyl ether, polyoxyethylene (20) stearyl ether, polyoxyethylene (10) oleyl ether, polyoxyethylene (10) cetyl ether, polyoxyethylene (10) Polyoxyethylene (n) alkyl ether (n is 20 to 100, alkyl chain length is C12 to C18) such as stearyl ether, polyoxyethylene (20) oleyl ether, and polyoxyethylene (100) stearyl ether. More preferred are defined nonionic surfactants. Also, N,N-bis[3-(D-gluconamido)propyl]deoxycholamide, n-dodecyl β-D-maltoside, octyl β-D-glucopyranoside, and digitonin can be used.

Nonionic surfactants include polyoxyethylene sorbitan monostearate (molecular formula: C ₆₄ H ₁₂₆ O ₂₆ , trade name: Tween 60, manufactured by Sigma-Aldrich, etc.), polyoxyethylene sorbitan trioleate (molecular formula: C ₂₄ H ₄₄ O ₆ , product name: Tween 85, manufactured by Sigma-Aldrich, etc.), octylphenol ethoxylate (molecular formula: C ₁₄ H ₂₂ O (C ₂ H ₄ O) _n , n = 1 to 10, product name: Triton X-100 , manufactured by Sigma-Aldrich, etc.), polyoxyethylene (40) isooctyl phenyl ether (molecular formula: C ₈ H ₁₇ C ₆ H ₄₀ (CH ₂ CH ₂₀ ) ₄₀ H, product name: Triton X-405, manufactured by Sigma-Aldrich) ), poloxamer (molecular formula: C ₅ H ₁₀ O ₂ , product name: Pluronic, manufactured by Sigma-Aldrich, etc.), polyvinylpyrrolidone (molecular formula: (C ₆ H ₉ NO) _n , n=5-100, manufactured by Sigma-Aldrich) etc.) can also be used.

By using a nonionic surfactant, the dispersibility of carbon nanotubes can be improved.
Furthermore, if a large amount of impurities such as surfactants remain in the carbon nanotube film, a sufficient bond may not be formed between the electrode and the carbon nanotubes. However, since the nonionic surfactant can be easily removed by heat treatment, etc., which will be described later, the amount remaining in the carbon nanotube film can be reduced, thereby preventing contact between the electrode and the carbon nanotube film. You can improve. In one embodiment, the surfactant in the bolometer membrane is preferably removed to reduce the residual amount of surfactant, as described below, and in one embodiment, the bolometer membrane substantially removes the surfactant. It is preferable not to include it. The bolometer membrane does not substantially contain a surfactant when the residual concentration of the surfactant is preferably 0.01% by mass or less, more preferably 0.001% by mass or less, based on the total mass of the bolometer membrane. (including 0% by mass).
In particular, the bolometer of this embodiment has the advantage that by suppressing increases in the thickness and density of the bolometer film in region B in contact with the electrode wall, residual impurities such as surfactants can be reduced.

The method for obtaining the carbon nanotube dispersion is not particularly limited, and conventionally known methods can be applied. For example, a carbon nanotube mixture, a dispersion medium, and a nonionic surfactant are mixed to prepare a solution containing carbon nanotubes, and this solution is treated with ultrasound to disperse the carbon nanotubes. Dispersion solution) is prepared. The dispersion medium is not particularly limited as long as it is a solvent that can disperse and suspend carbon nanotubes during the separation process. For example, water, heavy water, organic solvents, ionic liquids, or mixtures thereof can be used, but water and Heavy water is preferred. In addition to or in place of the ultrasonic treatment, a carbon nanotube dispersion method using mechanical shearing force may be used. Mechanical shearing may be performed in the gas phase. In a micelle-dispersed aqueous solution of carbon nanotubes and a nonionic surfactant, carbon nanotubes are preferably in an isolated state. Therefore, if necessary, bundles, amorphous carbon, impurity catalysts, etc. may be removed using ultracentrifugation treatment. During the dispersion treatment, the carbon nanotubes can be cut, and the length can be controlled by changing the pulverization conditions, ultrasonic output, ultrasonic treatment time, etc. of the carbon nanotubes. For example, untreated carbon nanotubes can be ground with tweezers, a ball mill, etc. to control the aggregate size. After these treatments, the length is controlled to 100 nm to 5 μm using an ultrasonic homogenizer with an output of 40 to 600 W, optionally 100 to 550 W, 20 to 100 KHz, and a treatment time of 1 to 5 hours, preferably ~3 hours. can do. If it is shorter than 1 hour, depending on the conditions, there may be little dispersion and the length may remain almost at its original length. Further, from the viewpoint of shortening the distributed processing time and reducing costs, the time is preferably 3 hours or less. This embodiment may also have the advantage that cutting can be easily adjusted by using a nonionic surfactant. It also has the advantage of not containing ionic surfactants that are difficult to remove.

By dispersing and cutting the carbon nanotubes, surface functional groups are generated on the surfaces or ends of the carbon nanotubes. The functional groups produced include carboxyl groups, carbonyl groups, and hydroxyl groups. If the treatment is in the liquid phase, carboxyl groups and hydroxyl groups are generated, and if the treatment is in the gas phase, carbonyl groups are generated.

Further, the concentration of the surfactant in the liquid containing the heavy water or water and the nonionic surfactant is preferably from the critical micelle concentration to 10% by mass, more preferably from the critical micelle concentration to 3% by mass. If it is less than the critical micelle concentration, it is not preferable because it cannot be dispersed. Further, if the amount is 10% by mass or less, carbon nanotubes with sufficient density can be applied after separation while reducing the amount of surfactant. In this specification, critical micelle concentration (CMC) is defined as the measurement of surface tension by changing the concentration of an aqueous surfactant solution using a surface tension meter such as a Wilhelmy surface tension meter at a constant temperature, for example. It refers to the concentration at which the inflection point occurs. In this specification, "critical micelle concentration" is a value at 25° C. under atmospheric pressure.

The concentration of carbon nanotubes in the above cutting and dispersion step (weight of carbon nanotubes/(total weight of carbon nanotubes, dispersion medium, and surfactant) x 100) is not particularly limited, but for example, 0.0003 to 10% by mass, The content is preferably 0.001 to 3% by mass, more preferably 0.003 to 0.3% by mass.

The dispersion liquid obtained through the above-mentioned cutting and dispersion process may be used as it is in the separation process described below, or may be subjected to processes such as concentration and dilution before the separation process.

Since carbon nanotubes are usually a mixture of semiconducting carbon nanotubes and metallic carbon nanotubes, it is preferable to separate or concentrate the semiconducting carbon nanotubes before use.
Carbon nanotubes can be separated by, for example, an electric field induced layer formation method (ELF method: see, for example, K. Ihara et al. J. Phys. Chem. C. 2011, 115, 22827-22832, Japanese Patent No. 5717233). , which documents are incorporated herein by reference). An example of a separation method using the ELF method will be explained. Carbon nanotubes, preferably single-walled carbon nanotubes, are dispersed with a nonionic surfactant, the dispersion is placed in a vertical separation device, and a voltage is applied to electrodes placed above and below to perform carrier-free electrophoresis. Separate by The mechanism of separation can be estimated as follows, for example. When carbon nanotubes are dispersed with a nonionic surfactant, micelles of semiconducting carbon nanotubes have a negative zeta potential, whereas micelles of metallic carbon nanotubes have a zeta potential of the opposite sign (positive) (in recent years, they have a slight zeta potential). It is also thought that it has a negative zeta potential or almost no charge). Therefore, when an electric field is applied to the carbon nanotube dispersion liquid, conductive carbon nanotube micelles electrophores toward the anode (+), and metal carbon nanotube micelles electrophores toward the cathode (-) due to the difference in zeta potential. Eventually, a layer in which semiconducting carbon nanotubes are concentrated near the anode and a layer in which metallic carbon nanotubes are concentrated near the cathode are formed in the separation tank. The separation voltage can be appropriately set in consideration of the composition of the dispersion medium, the charge amount of the carbon nanotubes, etc., but is preferably 1 V or more and 200 V or less, and more preferably 10 V or more and 200 V or less. From the viewpoint of shortening the time of the separation step, the voltage is preferably 100 V or more. Further, from the viewpoint of suppressing the generation of bubbles during separation and maintaining separation efficiency, the voltage is preferably 200 V or less. Purity improves by repeating separation. The dispersion liquid after separation may be reset to the initial concentration and a similar separation operation may be performed. Thereby, even higher purity can be achieved.

Through the carbon nanotube dispersion/cutting process and separation process described above, a dispersion liquid in which semiconducting carbon nanotubes having a desired diameter and length are concentrated can be obtained. Note that in this specification, a carbon nanotube dispersion liquid in which semiconducting carbon nanotubes are concentrated may be referred to as a "semiconducting carbon nanotube dispersion liquid." The semiconducting carbon nanotube dispersion obtained by the separation step generally contains semiconducting carbon nanotubes in an amount of 67% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably means a dispersion containing 90% by mass or more, more preferably 95% by mass or more, even more preferably 99% by mass or more (the upper limit may be 100% by mass). The separation tendency of metallic and semiconducting carbon nanotubes can be analyzed by microscopic Raman spectroscopy and ultraviolet-visible near-infrared absorption spectrometry.

After the carbon nanotube dispersion/cutting process described above and before the separation process, a centrifugal separation process may be performed to remove bundles, amorphous carbon, metal impurities, etc. from the carbon nanotube dispersion liquid. The centrifugal acceleration can be adjusted as appropriate, but is preferably 10,000 x g to 500,000 x g, more preferably 50,000 x g to 300,000 x g, and may be 100,000 x g to 300,000 x g depending on the case. The centrifugation time is preferably 0.5 to 12 hours, more preferably 1 to 3 hours. The centrifugation temperature can be adjusted as appropriate, but is preferably 4°C to room temperature, more preferably 10°C to room temperature.

The concentration of surfactant in the carbon nanotube dispersion after separation can be controlled as appropriate. The concentration of the surfactant in the carbon nanotube dispersion is preferably from the critical micelle concentration to about 0.5% by mass, more preferably from 0.001% by mass to 0.3% by mass, in order to suppress reagglomeration etc. after coating. 0.01 to 0.1% by mass is particularly preferred.

3. Step of Forming a Bolometer Film As described above, a bolometer film is formed by passing a substrate on which an electrode has been formed and surface treatment has been performed if necessary, through the surface of the carbon nanotube dispersion. The present inventors set the moving speed of the substrate within a predetermined range when passing the liquid surface of the carbon nanotube dispersion, so that the region A on the upper surface of the electrode and the region C between the electrodes on the substrate become the electrode wall. It was discovered for the first time that it is possible to form a bolometer film connected through the contact region B, and that it is thereby possible to reduce the resistance of the bolometer.

The moving speed at which the substrate passes through the surface of the carbon nanotube dispersion liquid is 5 μm/second or less, preferably 3 μm/second or less, and more preferably 2 μm/second or less.
Further, the step of passing the carbon nanotubes through the liquid surface may be performed two or more times. In this case, the movement speed/number of movements may be 5 μm/sec or less, and it is preferably 3 μm/sec or less. The speed is preferably 2 μm/sec or less, and more preferably 2 μm/sec or less. From the viewpoint of forming a homogeneous film, the number of movements is preferably 5 times or less, more preferably 3 times or less, and even more preferably 1 time.
Further, the lower limit of the movement speed/number of movements is not limited, but is 0.01 μm/second or more, preferably 0.02 μm/second or more.

The above-mentioned moving speed can also be adjusted as appropriate depending on the thickness of the electrode.
For example, when the height of the electrode is 50 nm to 150 nm, for example around 100 nm, the moving speed (moving speed/number of movements) is preferably 5 μm/sec or less, preferably 2 μm/sec or less, and the electrode height is In the case of more than 150 nm to 300 nm, for example around 250 nm, the moving speed (moving speed/number of movements) is preferably 2 μm/sec or less, more preferably 1 μm/sec or less.

Note that the above-mentioned moving speed can be adjusted as appropriate depending on humidity, temperature, etc. The humidity and temperature to which the above moving speed can be applied are 10 to 90% RH, preferably 30 to 80% RH, 5 to 40°C, preferably 15 to 30°C.

Further, the above-mentioned moving speed can be adjusted as appropriate depending on the concentration of carbon nanotubes in the carbon nanotube dispersion liquid used, the thickness of the film to be produced, and the like.

Furthermore, the present inventors have discovered that a bolometer film of a desired shape can be formed by further adjusting the moving speed.

For example, a bolometer film consisting of two or more carbon nanotube layers can be formed by reducing the movement speed/number of movements to 0.8 μm/sec or less, preferably 0.5 μm/sec or less.

Furthermore, the present inventors have made it possible to orient at least some of the carbon nanotubes approximately parallel to the liquid surface of the carbon nanotube dispersion (that is, approximately perpendicular to the direction of movement of the substrate) by further reducing the movement speed. We have found that it is possible to form a bolometer film while using this method.
As for the moving speed when aligning carbon nanotubes, the moving speed/number of movements is preferably 0.3 μm/sec or less, more preferably 0.2 μm/sec or less, for example, 0.1 μm/sec or less. This movement speed also depends on the speed at which the liquid interface moves on the substrate due to natural evaporation of the dispersion (e.g., approximately 0.1 to 0.01 μm/sec at humidity of 10 to 70 RH and room temperature (23°C)). Therefore, the moving speed may be adjusted depending on the relationship with conditions such as environmental humidity. In this embodiment, from the viewpoint of orientation, it is more preferable that the movement speed is 0.3 μm/sec or less (the number of times of movement is one).
When the moving speed is low, it is thought that the carbon nanotubes adhere to the substrate while being deposited on the substrate due to the coffee stain phenomenon at the liquid surface of the dispersion liquid. Depending on various conditions such as movement speed, the bolometer film (carbon nanotube layer) may be formed as a single oriented layer on the substrate, or it may be formed as a non-oriented layer (network structure or orientation layer) on the substrate. It is also possible to form a bolometer film consisting of two or more layers: a lower layer) and an alignment layer formed thereon.

When the substrate is passed through the liquid surface of the carbon nanotube dispersion, for example, the substrate may be immersed in a liquid bath of the carbon nanotube dispersion and then pulled up from the liquid bath. Alternatively, the substrate may be pushed down into a bath of carbon nanotube dispersion.
The method of moving the substrate is not particularly limited, and it may be done manually, or it may be placed on a jig that can be moved by pulling or pushing, so that the substrate passes through the surface of the carbon nanotube dispersion liquid. It may be moved in one direction. Examples of the jig for moving include, but are not limited to, a dip coater (FIG. 6), a constant speed moving machine, and the like.

As for the moving method, a constant speed pulling method is preferable. By moving at a constant speed, a bolometer film with a uniform thickness can be formed. Furthermore, since the portion (region B) in contact with the electrode wall moves at a relatively high speed with respect to the film formation surface, a bolometer film with a relatively low thickness or density can be formed. Furthermore, the method of this embodiment has the advantage that it is possible to prevent the bolometer film from becoming thicker in some areas, since a pool of the dispersion liquid is less likely to form at the connection between the electrode and the substrate.
The angle between the liquid surface and the substrate when passing the carbon nanotube dispersion liquid is not particularly limited, but it is preferably approximately perpendicular to the liquid surface, for example, 30 degrees or less from perfect verticality, preferably 20 degrees. Hereinafter, it is preferable that the deviation be within a range of, for example, 10° or less, and it is more preferable that the deviation be perpendicular.

The electrodes formed on the substrate and the liquid surface of the carbon nanotube dispersion may be moved in such a way that the current flowing between the electrodes is perpendicular to the direction of movement of the substrate, or the direction in which the current flows and the substrate The moving directions may be parallel to each other. In either case, a bolometer film can be formed in which region A on the upper surface of the electrode and region C between the electrodes are connected at region B in contact with the electrode wall. In addition, when forming an alignment film, it is possible to increase the height of A low resistance effect can be obtained.
Note that in this specification, the terms "parallel" and "perpendicular" expressing directions may include "substantially parallel" and "substantially perpendicular", respectively. "Substantially parallel" and "substantially perpendicular" may include aspects that are deviated from completely "parallel" and "perpendicular" by 30 degrees or less, preferably 20 degrees or less, more preferably 10 degrees or less.

As described above, after the carbon nanotubes in the dispersion are allowed to adhere to the substrate and electrodes by passing the substrate through the surface of the carbon nanotube dispersion, cleaning treatment with water, ethanol, isopropyl alcohol, etc. The surfactant and solvent in the dispersion can be removed by heat treatment. The temperature of the heat treatment can be set appropriately above the decomposition temperature of the surfactant, but is preferably 150 to 500°C, more preferably 160 to 500°C, for example 180 to 400°C. A temperature of 180° C. or higher is more preferable because it is easier to suppress the residual decomposition products of the surfactant. Further, if the temperature is 500° C. or lower, for example 400° C. or lower, deterioration of the substrate and other components can be suppressed, which is preferable. Further, it is possible to suppress decomposition and size change of carbon nanotubes, separation of functional groups, etc.

4. Additional Steps As described above, after forming the bolometer film on the substrate with electrodes formed on its surface, a protective film or an infrared absorbing structure may be formed, if desired. For these steps, the steps used in the manufacturing process of a bolometer can be applied without restriction as appropriate.

[Additional notes]
Although some or all of the above embodiments may be described as in the following additional notes, the disclosure of the present application is not limited to the following additional notes.

(Additional note 1)
A bolometer comprising two electrodes provided on a substrate and a bolometer film containing carbon nanotubes,
The bolometer film is provided to connect the upper surface area of the two electrodes, the area in contact with the electrode wall of the two electrodes, and the area between the two electrodes on the substrate,
The area density of the region of the bolometer film in contact with the electrode wall is less than or equal to the area density of the region between the electrodes on the substrate, or the film thickness of the region of the bolometer film in contact with the electrode wall is less than or equal to the film thickness of the region between the electrodes on the substrate. Yes, a bolometer.
(Additional note 2)
The bolometer according to supplementary note 1, wherein the bolometer film consists of one or more non-oriented carbon nanotube layers.
(Appendix 3)
The bolometer film is composed of two or more non-oriented carbon nanotube layers, and at least one layer connects the top surfaces of the two electrodes, the electrode walls of the two electrodes, and the area between the two electrodes on the substrate. The bolometer according to appendix 2, which is provided.
(Additional note 4)
The bolometer according to supplementary note 1, wherein the bolometer film includes an alignment layer in which at least some of the carbon nanotubes are aligned.
(Appendix 5)
The bolometer according to appendix 4, wherein the alignment layer is provided so as to connect the upper surfaces of the two electrodes, the electrode walls of the two electrodes, and the region between the two electrodes on the substrate.
(Appendix 6)
The bolometer membrane is
an orientation layer in which at least some of the carbon nanotubes are oriented;
a non-oriented layer in which the carbon nanotubes are oriented in different directions;
including two layers of
The bolometer according to appendix 4, wherein at least the alignment layer is provided to connect the upper surfaces of the two electrodes, the electrode walls of the two electrodes, and the region between the two electrodes on the substrate.
(Appendix 7)
The area density of the area of the bolometer film in contact with the electrode wall is 90% or less of the area density of the area between the electrodes on the substrate, or the film thickness of the area of the bolometer film in contact with the electrode wall is the film in the area between the electrodes on the substrate. The bolometer according to any one of appendices 1 to 6, which has a thickness of 90% or less.
(Appendix 8)
The bolometer according to any one of appendices 1 to 7, wherein the electrode has a thickness of 50 nm or more.
(Appendix 9)
The bolometer according to any one of appendices 1 to 8, wherein the bolometer film contains semiconducting carbon nanotubes in an amount of 90% by mass or more based on the total amount of carbon nanotubes.
(Appendix 10)
A method for manufacturing a bolometer comprising two electrodes provided on a substrate and a bolometer film containing carbon nanotubes, the method comprising:
The substrate with electrodes formed on its surface is passed through the liquid surface of the carbon nanotube dispersion liquid at a movement speed/number of movements of 5 μm/sec or less. A manufacturing method comprising the step of forming an electrode wall of two electrodes and a region between two electrodes on a substrate so as to connect them.
(Appendix 11)
The manufacturing method according to appendix 10, wherein the moving speed is 5 μm/sec or less.
(Appendix 12)
The manufacturing method according to appendix 10, wherein a bolometer film consisting of one or more non-oriented carbon nanotube layers is formed.
(Appendix 13)
A bolometer film consisting of two or more non-oriented carbon nanotube layers is formed, with at least one layer connecting the top surfaces of the two electrodes, the electrode walls of the two electrodes, and the area between the two electrodes on the substrate. The manufacturing method according to appendix 12, wherein the manufacturing method is formed.
(Appendix 14)
A substrate with electrodes formed on its surface is passed through the liquid surface of the carbon nanotube dispersion at a movement speed/number of times of movement of 0.3 μm/sec or less, whereby at least some of the carbon nanotubes are oriented. The manufacturing method according to appendix 10, comprising the step of forming a bolometer film including a layer so as to connect the upper surfaces of the two electrodes, the electrode walls of the two electrodes, and the region between the two electrodes on the substrate.
(Additional note 15)
15. The manufacturing method according to any one of appendices 10 to 14, wherein the substrate having an electrode formed on its surface is moved using a constant speed pulling method.
(Appendix 16)
comprising a step of preparing a carbon nanotube dispersion,
The step of preparing a carbon nanotube dispersion includes the step of subjecting a dispersion of a mixture of metallic carbon nanotubes and semiconducting carbon nanotubes to carrier-free electrophoresis to prepare a carbon nanotube dispersion containing semiconducting carbon nanotubes. The manufacturing method according to any one of Supplementary Notes 10 to 15.
(Appendix 17)
17. The manufacturing method according to any one of appendices 10 to 16, wherein the carbon nanotube dispersion liquid contains semiconducting carbon nanotubes in an amount of 90% by mass or more based on the total amount of carbon nanotubes.

EXAMPLES Hereinafter, the present invention will be illustrated in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Example 1)
Step 1: Preparation of carbon nanotube dispersion 100 mg of single-walled carbon nanotubes (Meijo Nano Carbon Co., Ltd., EC1.0 (diameter: about 1.1 to 1.5 nm, average diameter 1.2 nm) were placed in a quartz boat, and vacuum Heat treatment was performed using an electric furnace in an atmosphere.The heat treatment was performed at a temperature of 900°C for 2 hours.The weight after heat treatment was reduced to 80 mg, and surface functional groups and impurities were removed. After crushing the obtained single-walled carbon nanotubes with tweezers, 12 mg was immersed in 40 ml of a 1 wt% surfactant (polyoxyethylene (100) stearyl ether) aqueous solution, and after being sufficiently submerged, Ultrasonic dispersion treatment (BRANSON ADVANCED-DIGITAL SONIFIER device, output 50 W) was performed for 3 hours. As a result, there were no aggregates of carbon nanotubes in the solution. Through this operation, bundles, residual catalyst, etc. were removed, and carbon A nanotube dispersion was obtained. In order to observe the length and diameter of the carbon nanotubes, this dispersion was applied onto a SiO ₂ substrate, dried at 100° C., and then observed using an atomic force microscope (AFM). As a result, it was found that 70% of the single-walled carbon nanotubes had a length in the range of 500 nm to 3 μm, and the average length was approximately 800 nm.
The carbon nanotube dispersion obtained above was introduced into a separation device having a double tube structure. About 15 ml of water, about 70 ml of carbon nanotube dispersion, and about 10 ml of a 2 wt % aqueous surfactant solution were put into the outer tube of the double tube, and about 20 ml of a 2 wt % aqueous surfactant solution was also put into the inner tube. Then, by opening the lower lid of the inner tube, a three-layer structure with different surfactant concentrations was created. By applying a voltage of 200 V using the lower side of the inner tube as an anode and the upper side of the outer tube as a cathode, the semiconducting carbon nanotubes moved to the anode side. On the other hand, the metallic carbon nanotubes moved toward the cathode. Semiconductor-type and metallic-type carbon nanotubes were clearly separated about 80 hours after the start of separation. The separation step was performed at room temperature (approximately 25°C). When the semiconducting carbon nanotube dispersion liquid that had moved to the anode side was recovered and analyzed by optical absorption spectroscopy, it was found that the metallic carbon nanotube component had been removed. Moreover, from the Raman spectrum, 99 wt % of the carbon nanotubes in the carbon nanotube dispersion liquid that moved to the anode side were semiconductor carbon nanotubes. The diameter of the single-walled carbon nanotubes was approximately 1.2 nm in most cases (more than 70%), and the average diameter was 1.2 nm.
A portion of the surfactant was removed from the carbon nanotube dispersion containing 99 wt % of the semiconducting carbon nanotubes (the carbon nanotube dispersion that had moved to the anode side), so that the concentration of the surfactant was 0.05 wt %. Thereafter, carbon nanotube dispersion A (referred to as dispersion A) was adjusted so that the concentration of carbon nanotubes in the dispersion was 0.01 wt%. This dispersion liquid A was used to form a carbon nanotube layer.

Step 2: Formation of Electrodes The Si substrate on which SiO ₂ was formed was subjected to oxygen plasma treatment, then a photoresist was applied, and the electrodes were patterned so that the distance between the electrodes was 100 μm. For the electrodes, Ti was deposited to a thickness of 5 nm and Au to a thickness of 100 nm for both the first and second electrodes by E-gun deposition, and the resist was lifted off.
This substrate with electrodes was sequentially washed with acetone, isopropyl alcohol, and water, and organic matter on the surface was removed by oxygen plasma treatment. The substrate was immersed in a 0.1% by volume APTES aqueous solution for 30 minutes, washed with water, and then dried.

Step 3: Formation of bolometer film The substrate with electrodes formed on the surface prepared in Step 2 is fixed to a dip coater so that the direction of movement is perpendicular to the direction in which current flows through the electrode pair, and the electrode portion is formed in Step 1. After being immersed in a liquid bath of the prepared carbon nanotube dispersion A, an operation of vertically pulling it up at a speed of 4 μm/sec was performed once. After washing with water and isopropyl alcohol, it was dried and heated in the atmosphere at 200°C to remove nonionic surfactants and the like.

(Examples 2 to 4)
A bolometer film was formed in the same manner as in Example 1, except that the operation of pulling up the substrate from the carbon nanotube dispersion liquid A was carried out at the movement speed and number of movements listed in Table 1. In Example 4, the operation of immersing the substrate in a liquid bath and pulling it up at a speed of 10 μm/sec was repeated five times.
The results are shown in Table 1.

(Example 5)
In step 3, the substrate was fixed to a dip coater so that the direction of movement was parallel to the direction in which current flows through the electrode pair, and the operation of pulling the substrate up was performed once at 0.1 μm/sec. A bolometer film was formed in the same manner as in Example 1.

(Example 6)
In step 3, the substrate was fixed to a dip coater so that the direction of movement was perpendicular to the direction in which current flows through the electrode pair, and the operation of lifting the substrate was performed once at 0.1 μm/sec. A bolometer film was formed in the same manner as in Example 1.

(Example 7)
In step 3, the substrate was fixed to a dip coater so that the direction of movement was perpendicular to the direction in which current flows through the electrode pair, and the operation of pulling up the substrate was performed once at 0.4 μm/sec. A bolometer film was formed in the same manner as in Example 1.

(Comparative example 1)
Steps 1 and 2 were performed in the same manner as in Example 1. In step 3, about 100 μL of CNT dispersion liquid A was dropped onto the APTES-attached substrate, the dispersion liquid was spread over the entire surface of the substrate, and the mixture was left standing for 30 minutes. After washing with water and isopropyl alcohol, it was dried and heated in the atmosphere at 200°C to remove nonionic surfactants and the like.
SEM observation of the substrate revealed that carbon nanotubes were attached in a random network. The thickness of the carbon nanotube layer was estimated from SEM observation to be about 10 nm on average.

(Comparative example 2)
In step 3, approximately 100 μL of CNT dispersion liquid A is dropped onto the APTES-attached substrate, the dispersion liquid is spread over the entire surface of the substrate, it is left standing for 30 minutes, the liquid is discarded and dried, and the CNT dispersion liquid is again dispersed on top of the substrate. A bolometer film was formed in the same manner as in Comparative Example 1, except that about 100 μL of Solution A was dropped onto the substrate, the dispersion was spread over the entire surface of the substrate, and the dispersion was allowed to stand for 30 minutes, followed by washing with water and isopropyl alcohol.
SEM observation of the substrate revealed that carbon nanotubes were attached in a random network. The thickness of the carbon nanotube layer was estimated from SEM observation to be about 30 nm on average.

(Comparative Examples 3 to 5)
A bolometer film was formed in the same manner as in Example 1, except that the operation of pulling up the substrate from the carbon nanotube dispersion liquid A was carried out at the movement speed and number of movements listed in Table 1.

Results Table 1 shows the results of the connection of carbon nanotube layers, the thickness of the carbon nanotube layer (between electrodes), the area density ratio of the carbon nanotube layer, and the resistance at 3V for the produced bolometer.

The area density ratio of the carbon nanotube layer was calculated by the following method.
(1) Calculation of carbon nanotube occupancy rate In the SEM images of 10 random points (field of view 100 nm x 1 μm) for each of the region of the formed carbon nanotube layer on the substrate (between the electrodes) and the region in contact with the electrode wall, Using the analysis software "WinROOF", we cut out the part where carbon nanotubes exist and the gap part where there are no carbon nanotubes, and calculated the carbon nanotube occupancy rate.
[Carbon nanotube occupancy rate = Area of the part where carbon nanotubes exist/(Area of the part where carbon nanotubes exist + Area of the gap where carbon nanotubes do not exist)]
It was calculated as
(2) Calculation of area density ratio The area density ratio is
[Carbon nanotube occupancy rate in the area in contact with the electrode wall/carbon nanotube occupancy rate in the area on the substrate (between the electrodes)]
It was calculated as

(Evaluation of Examples 1 to 4 and Comparative Examples 1 to 2)
As shown in Table 1, in the bolometers of Examples 1 to 4, a remarkable effect of lowering the resistance was observed compared to the bolometers of Comparative Examples 1 and 2.
In the bolometer films of Examples 1 to 4, it was confirmed that the carbon nanotube layer on the substrate (between the electrodes) and the carbon nanotube layer on the top surface of the electrode were connected by the carbon nanotube layer in contact with the electrode wall (Figure 7). . Further, the area density ratios were all less than 100%, and it was confirmed that the density of the carbon nanotube layer on the electrode wall was lower than that of the carbon nanotube layer on the substrate (between the electrodes).
On the other hand, in the bolometer films of Comparative Examples 1 and 2, the carbon nanotube layer on the substrate (between the electrodes) and the carbon nanotube layer on the top surface of the electrodes were not connected.
Further, when Comparative Example 1 and Comparative Example 2 were compared, Comparative Example 2 had a thicker carbon nanotube layer and a larger contact area with the electrode, but had higher resistance. This result suggests that when the thickness of the carbon nanotube layer is appropriately thin as in Comparative Example 1, the surfactant can be completely removed, resulting in lower resistance.
From these results, Examples 1 to 4 are superior to Comparative Examples 1 to 2 because the carbon nanotubes on the substrate and the top surface of the electrode are connected and there is no thick part in the bolometer film. It is thought that the effect of lowering resistance was obtained.

(Evaluation of Examples 1 to 4 and Comparative Examples 3 to 5)
In the bolometers of Comparative Examples 3 to 5, bolometer films were formed using the same pulling method as in Examples 1 to 4, but because the moving speed was fast, the carbon nanotube layer on the substrate (between the electrodes) and the carbon nanotubes on the top surface of the electrodes were separated. Layers did not connect. Therefore, the resistance was higher than that in Examples 1 to 4.

(Evaluation of Examples 5 to 7)
In Examples 5 and 6, by reducing the moving speed of the substrate, it was possible to create a bolometer film in which carbon nanotubes were oriented in a direction parallel to the liquid surface of the carbon nanotube dispersion (FIG. 8). The SEM image is subjected to two-dimensional Fourier transform processing (Fig. 9), and the integrated value f of the amplitude from frequency -1 μm ^-1 to +1 μm ^-1 in one direction from the center is calculated, and the integrated value f is calculated in relation to the direction x where the integrated value f is maximum. When the integrated value is fx and the integrated value in the direction y perpendicular to the direction x is fy, fx/fy was calculated to be 1.8 in Example 5 and 2.0 in Example 6.
In Example 6, in which the carbon nanotubes were oriented parallel to the electrodes (perpendicular to the direction of current flow), a resistance reduction effect equivalent to that of the bolometers of Examples 1 to 4 was obtained. Further, in Example 6, in which the carbon nanotubes were oriented perpendicular to the electrodes (parallel to the direction in which the current flows), a further lower resistance effect than in Example 5 was achieved.
In addition, all of the carbon nanotube alignment films obtained in Examples 5 and 6 had a two-layer structure, as shown in FIG. 10, with the upper layer being an alignment layer and the lower layer close to the substrate being a network-like non-alignment layer. It was found that the carbon nanotubes on the substrate (between the electrodes) and the carbon nanotubes on the top surface of the electrode were connected in the upper layer with the carbon nanotubes in contact with the electrode wall (Figures 8, 9, and 10 show the results of Example 6). ).
In Example 7, by making the moving speed of the substrate slightly higher than in Examples 5 and 6, it was possible to produce a carbon nanotube film having a two-layer structure, but in which both layers were non-oriented. It was confirmed that the upper layer of this two-layer non-oriented film has a carbon nanotube layer on the substrate (between the electrodes) and a carbon nanotube layer on the top surface of the electrode, which are connected by a carbon nanotube layer in contact with the electrode wall. (Figure 11). The non-oriented film of Example 7 also had the same resistance reduction effect as the bolometers of Examples 1 to 4.

(Example 8)
Step 1: Preparation of carbon nanotube dispersion In the same manner as in Example 1, carbon nanotube dispersion A (described as dispersion A) was prepared so that the concentration of carbon nanotubes in the dispersion was 0.01 wt%. This dispersion liquid A was used to form a carbon nanotube layer.

Step 2: Formation of Electrodes The Si substrate on which SiO ₂ was formed was subjected to oxygen plasma treatment, then a photoresist was applied, and the electrodes were patterned so that the distance between the electrodes was 100 μm. For the electrodes, Ti was deposited to a thickness of 5 nm and Au to a thickness of 100 nm for both the first and second electrodes by E-gun deposition, and the resist was lifted off.
This substrate with electrodes was sequentially washed with acetone, isopropyl alcohol, and water, and organic matter on the surface was removed by oxygen plasma treatment.

Step 3: Formation of bolometer film The substrate with electrodes formed on the surface prepared in Step 2 is fixed to a dip coater so that the direction of movement is perpendicular to the direction in which current flows through the electrode pair, and the electrode portion is formed in Step 1. After being immersed in a liquid bath of the prepared carbon nanotube dispersion A, an operation of vertically pulling it up at a speed of 0.1 μm/sec was performed once. After washing with water and isopropyl alcohol, it was dried and heated in the atmosphere at 200°C to remove nonionic surfactants and the like.

(Comparative example 6)
Steps 1 and 2 were performed in the same manner as in Example 8. In step 3, approximately 100 μL of carbon nanotube dispersion A was dropped onto the substrate, the dispersion was spread over the entire surface of the substrate, and the dispersion was left standing for 30 minutes. After washing with water and isopropyl alcohol, it was dried and heated in the atmosphere at 200°C to remove nonionic surfactants and the like.

Results Table 2 shows the results of the connection of the carbon nanotube layers, the thickness of the carbon nanotube layer (between the electrodes), the area density ratio of the carbon nanotube layers, and the resistance at 3V for the produced bolometer.

(Evaluation of Example 8 and Comparative Example 6)
As shown in Table 2, a significant resistance reduction effect was observed in the bolometer of Example 8 compared to the bolometer of Comparative Example 6.
In the bolometer film of Example 8, it was confirmed that the carbon nanotube layer on the substrate (between the electrodes) and the carbon nanotube layer on the upper surface of the electrode were connected by the carbon nanotube layer in contact with the electrode wall. In Example 8, by not creating an intermediate layer such as an APTES layer and by slowing down the moving speed of the substrate, carbon nanotubes were arranged parallel to the direction of the current in both the lower layer and the upper layer near the substrate. It was oriented (Fig. 12).
On the other hand, in the bolometer film of Comparative Example 6, carbon nanotubes in a random network form were only slightly attached to the substrate, and the carbon nanotube layer on the substrate (between the electrodes) was connected to the carbon nanotube layer on the top surface of the electrodes. It wasn't.
From these results, in Example 8, the carbon nanotube layer is an alignment layer, and the carbon nanotubes on the substrate and the top surface of the electrode are connected, so it has a superior resistance reduction effect compared to Comparative Example 6. This is considered to have been obtained.

1 Substrate 2 First electrode 3 Bolometer film 4 Second electrode 5 CNT film on electrode 6 CNT film between electrodes 7 Electrode

Claims (10)

A bolometer comprising two electrodes provided on a substrate and a bolometer film containing carbon nanotubes,
The bolometer film is provided to connect the upper surface area of the two electrodes, the area in contact with the electrode wall of the two electrodes, and the area between the two electrodes on the substrate,
The area density of the region of the bolometer film in contact with the electrode wall is less than or equal to the area density of the region between the electrodes on the substrate, or the film thickness of the region of the bolometer film in contact with the electrode wall is less than or equal to the film thickness of the region between the electrodes on the substrate. Yes, a bolometer. The bolometer according to claim 1, wherein the bolometer film consists of one or more non-oriented carbon nanotube layers. The bolometer according to claim 1, wherein the bolometer film includes an orientation layer in which at least some of the carbon nanotubes are oriented. 4. The bolometer according to claim 3, wherein the alignment layer is provided to connect the top surfaces of the two electrodes, the electrode walls of the two electrodes, and the area between the two electrodes on the substrate. The bolometer membrane is
an orientation layer in which at least some of the carbon nanotubes are oriented;
a non-oriented layer in which the carbon nanotubes are oriented in different directions;
including two layers of
The bolometer according to claim 3, wherein at least the alignment layer is provided to connect the top surfaces of the two electrodes, the electrode walls of the two electrodes, and the region between the two electrodes on the substrate. The area density of the area of the bolometer film in contact with the electrode wall is 90% or less of the area density of the area between the electrodes on the substrate, or the film thickness of the area of the bolometer film in contact with the electrode wall is the film in the area between the electrodes on the substrate. The bolometer according to any one of claims 1 to 3, having a thickness of 90% or less. A method for manufacturing a bolometer comprising two electrodes provided on a substrate and a bolometer film containing carbon nanotubes, the method comprising:
The substrate with electrodes formed on its surface is passed through the liquid surface of the carbon nanotube dispersion liquid at a movement speed/number of movements of 5 μm/sec or less. A manufacturing method comprising the step of forming an electrode wall of two electrodes and a region between two electrodes on a substrate so as to connect them. A substrate having an electrode formed on its surface is passed through the liquid surface of the carbon nanotube dispersion at a movement speed/number of times of movement of 0.3 μm/sec or less, whereby at least some of the carbon nanotubes are oriented. 8. The manufacturing method according to claim 7, comprising forming a bolometer film including a layer to connect the upper surfaces of the two electrodes, the electrode walls of the two electrodes, and the region between the two electrodes on the substrate. 9. The manufacturing method according to claim 7, wherein the substrate having electrodes formed on its surface is moved using a constant speed pulling method. comprising a step of preparing a carbon nanotube dispersion,
The step of preparing a carbon nanotube dispersion includes the step of subjecting a dispersion of a mixture of metallic carbon nanotubes and semiconducting carbon nanotubes to carrier-free electrophoresis to prepare a carbon nanotube dispersion containing semiconducting carbon nanotubes. The manufacturing method according to claim 7 or 8.

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