Bolometer, method for detection, and method for manufacturing bolometer

Abstract

To provide a bolometer with a high TCR, a method for detection, and a method for manufacturing a bolometer.SOLUTION: The bolometer includes: a gate electrode to which a gate voltage can be applied; a drain electrode to which a drain voltage can be applied; a source electrode; and a first film connecting the drain electrode and the source electrode to each other, the first film containing a carbon nano tube. When the drain voltage is negative, the gate voltage is set to be between a first upper limit value and a first lower limit value, the first upper limit value being a gate voltage when the drain current of the drain electrode is the smallest and the first lower limit value being a gate voltage which satisfies the Expressions (1) and (2): the first lower limit value=the first upper limit value-(the first upper limit value-the medium value)×2...Expression (2).SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present disclosure relates to bolometers, detection methods, and methods of manufacturing bolometers. [Background technology]

[0002] It is known to use a bolometer as an infrared sensor.

[0003] For example, Patent Document 1 discloses a bolometer that uses a semiconducting carbon nanotube (CNT) to improve the temperature coefficient of resistance (TCR), which is related to improved performance of an infrared sensor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-49207 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the infrared receiving element disclosed in Patent Document 1, the position of the Fermi energy of the channel portion containing CNT is controlled by doping the channel portion with a control member containing an electrolyte. In addition, in this infrared receiving element, it is disclosed that the position of the Fermi energy of the channel portion containing CNT is further controlled by setting the voltage between the source electrode and the drain electrode and the voltage between the source electrode and the gate electrode, and as a result, the value of TCR is controlled. However, depending on the voltage value set, it may be difficult to achieve a high TCR.

[0006] An object of the present disclosure is to provide a bolometer, a detection method, and a method for manufacturing a bolometer that solves the above-mentioned problems. [Means for solving the problem]

[0007] The bolometer of the present disclosure comprises a gate electrode to which a gate voltage can be applied, a drain electrode to which a drain voltage can be applied, a source electrode, and a first film connecting the drain electrode and the source electrode and containing carbon nanotubes, wherein when the drain voltage is negative, the gate voltage is set between a first upper limit value and a first lower limit value, the first upper limit value being the gate voltage when the drain current of the drain electrode is at a minimum, and the first lower limit value being the gate voltage that satisfies the relationship between equations (1) and (2).

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[0008] The detection method disclosed herein includes applying a negative drain voltage to a drain electrode of a bolometer including a gate electrode, a drain electrode, a source electrode, and a first film connecting the drain electrode and the source electrode and including a carbon nanotube, and applying a gate voltage between a first upper limit value and a first lower limit value to the gate electrode to detect infrared rays, the first upper limit value being the gate voltage when the drain current of the drain electrode is at a minimum, and the first lower limit value being the gate voltage that satisfies the relationship between equations (1) and (2).

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[0009] The method for manufacturing a bolometer disclosed herein includes connecting a drain electrode and a source electrode, laminating a first film containing carbon nanotubes, and providing a second film on the surface of the first film for doping the first film, and providing the second film such that, in the step of providing the second film, when a drain voltage applied to the drain electrode is negative, a gate voltage applied to a gate electrode is set between a first upper limit value and a first lower limit value, the first upper limit value being the gate voltage when the drain current of the drain electrode is at a minimum, and the first lower limit value being the gate voltage having the relationship between equations (1) and (2).

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[0010] The bolometer, detection method, and bolometer manufacturing method according to the present disclosure facilitate high TCR. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view I showing an example of the configuration of a bolometer according to the present disclosure. [Diagram 2] 1 is a graph I showing an example of transport characteristics of a bolometer according to the present disclosure. [Diagram 3] Graph II illustrates an example of transport characteristics of a bolometer according to the present disclosure. [Figure 4] 1 is a graph I showing an example of the slope of the transport characteristic calculated based on the transport characteristic of a bolometer according to the present disclosure. [Diagram 5] 1 is a flowchart I showing an example of a process of a detection method according to the present disclosure. [Figure 6] 1 is a graph showing the relationship between the TCR and the slope of the transport characteristic of a bolometer according to the present disclosure. [Figure 7] 2 is a cross-sectional view II showing an example of the configuration of a bolometer according to the present disclosure. [Figure 8]Graph III illustrates an example of transport characteristics of a bolometer according to the present disclosure. [Figure 9] Graph II shows an example of the slope of the transport characteristic calculated based on the transport characteristic of a bolometer according to the present disclosure. [Figure 10] 4 is a flowchart illustrating an example of a process for a bolometer manufacturing method according to the present disclosure. [Figure 11] 4 is a graph IV showing an example of transport characteristics of a bolometer according to the present disclosure. [Figure 12] 3 is a cross-sectional view III showing an example of the configuration of a bolometer according to the present disclosure. [Figure 13] 11 is a flowchart II showing an example of a process of a detection method according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, each embodiment of the present disclosure will be described with reference to the drawings. Note that the drawings and specific configurations used in each embodiment should not be used to interpret the disclosure. The same or corresponding configurations in all drawings are given the same reference numerals, and common descriptions are omitted. It should be noted that in this disclosure, the drawings may relate to one or more embodiments.

[0013] An example of the configuration of a bolometer according to the present disclosure will now be described with reference to FIGS.

[0014] (Bolometer configuration) The bolometer 1 is used as a sensor for detecting infrared rays. As shown in FIG. 1, the bolometer 1 includes a substrate 11, a gate electrode 12, an insulating layer 13, a drain electrode 14, a source electrode 15, a first film 16, a second film 17, and an infrared absorbing layer 20.

[0015] (substrate) The substrate 11 is a Si substrate processed using a silicon wafer. For example, the substrate 11 may have a readout circuit formed thereon. For example, in order to ensure a sufficient amount of temperature rise due to infrared absorption, the substrate 11 may be formed with a MEMS (Micro Electro Mechanical Systems) structure in which the lower part of the bolometer is hollow. For example, a polymer film such as Parylene (registered trademark) having low thermal conductivity may be formed on the substrate 11 in order to ensure heat insulation. For example, the substrate 11 may have an electrically insulating base insulating layer. Methods for forming the base insulating layer include a method of subjecting the substrate 11 to heat treatment, a method of directly forming the base insulating layer by a CVD (Chemical Vapor Deposition) method, and a method of applying a solution in which a polymer or a polymer precursor is dissolved by spin coating and forming a polymer film by a heat treatment. Examples of the base insulating layer include silicon oxide, silicon nitride, polyimide, and Parylene (registered trademark). On a portion P of the surface of the substrate 11, a gate electrode 12, which will be described later, is provided.

[0016] (insulating layer) An insulating layer 13 is provided on a portion of the surface of the substrate 11 with a gate electrode 12 interposed therebetween. The insulating layer 13 is laminated so as to cover the surface of the substrate 11 and the surface of the gate electrode 12 . For example, the insulating layer 13 may have a thickness sufficient to protect the first film 16 from P-type doping by water or oxygen.

[0017] (gate electrode) The gate electrode 12 is provided on the surface of the substrate 11 . A gate voltage can be applied to the gate electrode 12 . The gate voltage is the voltage applied to the gate electrode 12 relative to the source electrode 15 .

[0018] (Drain electrode) The drain electrode 14 is provided on the surface of the insulating layer 13 . A drain voltage can be applied to the drain electrode 14 . The drain voltage is the voltage applied to the drain electrode 14 relative to the source electrode 15 . For example, a negative voltage may be applied to the drain voltage.

[0019] (Source electrode) The source electrode 15 is provided on the surface of the insulating layer 13 . For example, the source electrode 15 is connected to GND (ground).

[0020] (first membrane) The first film 16 connects the drain electrode 14 and the source electrode 15 . For example, a first film 16 covers the drain electrode 14 and the source electrode 15 . The first film 16 includes CNTs 161 . For example, in the present disclosure, the first film 16 has a CNT network formed by a plurality of CNTs 161 . Carriers are induced in the CNTs 161 included in the first film 16 by the gate voltage. As a result, a drain current flows between the drain electrode 14 and the source electrode 15. The induced carriers in the CNTs 161 change according to the doping effect of the second film 17, which will be described later. CNT161 is a fibrous material with a diameter of 0.6 to 1.5 nm and a length of 100 nm to 5.0 um. The properties of CNT161 change depending on the arrangement of the six-membered rings in the circumferential direction. Regarding CNT161, a cylindrical CNT made of a single graphene sheet is called a single-walled CNT, a CNT in which multiple CNTs of different diameters are stacked coaxially to form multiple layers is called a multi-walled CNT, and a CNT with two layers is called a double-walled CNT. For example, the CNT 161 may be any of a single-walled CNT, a double-walled CNT, and a multi-walled CNT. As an example, CNT 161 of the present disclosure is a single-walled CNT. CNT161 exists in two types: semiconducting type, which exhibits semiconducting properties, and metallic type, which exhibits metallic properties. Single-walled CNTs usually contain semiconducting CNTs and metallic CNTs in a ratio of 2:1. Therefore, when using a large amount of CNTs that exhibit one type of properties, a separation process is necessary. For example, the CNT 161 may be a semiconducting CNT, which can improve the absolute value of the TCR of the bolometer 1.

[0021] (Second membrane) The second film 17 is provided on the surface of the first film 16 . The second film 17 provides a doping effect to the first film 16 . The second film 17 has a doping effect of donating electrons to the CNTs 161 contained in the first film 16 (carriers induced by the gate voltage become electrons: N-type doping) or withdrawing electrons (carriers induced by the gate voltage become holes: P-type doping). For example, the second film 17 includes PMMA. The PMMA film formed using a solution of PMMA (poly methyl methacrylate) dissolved in anisole performs P-type doping on the CNTs 161 included in the first film 16. In FIG. 2, the transport properties of a bolometer 1 having a CNT network in the first film 16, in which the CNTs 161 are P-doped, are shown. FIG. 2 shows, as transport characteristics, the drain current value obtained at each gate voltage value for the bolometer 1 when the gate voltage is swept over a predetermined range. In FIG. 2, the two-dot chain line indicates the transport characteristics in a state where a drain voltage of -0.1 V is applied to the bolometer 1 in an environment of 303 K. In FIG. 2, the one-dot chain line indicates the transport characteristics in a state where a drain voltage of -0.1 V is applied to the bolometer 1 in an environment of 298 K. In FIG. 2, the gate voltage is swept in the range of -15 V to 15 V from each state, and the gate voltage value (Gate Voltage: V g The drain current (I d2, the solid line is a curve (TCR curve) showing the TCR value calculated based on the transport characteristic shown by the two-dot chain line and the transport characteristic shown by the one-dot chain line versus each gate voltage value. For example, the second film 17 may be an insulating film made of silicon oxide, alumina, or the like.

[0022] (Infrared absorbing layer) An infrared absorbing layer 20 may be provided to improve the infrared absorption of the bolometer 1 . The infrared absorbing layer 20 is provided on the surface of the second film 17 . The material used for the infrared absorbing layer 20 may be a carbon material such as gold black, carbon nanotube, carbon nanohorn, or carbon black, or a composite material of a carbon material and a polymer resin. In this case, the polymer resin may be PVA, PMMA, P4VP, or the like, but is not limited to these three types as long as it can uniformly disperse CNTs and maintain the structure of the polymer resin.

[0023] (Upper and lower limits of gate voltage) For example, in the bolometer 1, when the drain voltage is negative, the gate voltage is set between a first upper limit value and a first lower limit value, which will be described later. Here, the "first upper limit value" and the "first lower limit value" of the gate voltage will be described in detail with reference to Figures 3 to 4. The determination of the first upper limit value, the first lower limit value, and the median value described below also corresponds to some steps of the detection method of the present disclosure. 3 and 4, the CNT 161 is p-type doped with a PMMA film (second film 17) formed using an anisole-dispersed PMMA solution. In FIG. 3, the dashed line indicates the drain voltage (V d ) -0.1V was applied, and the gate voltage was swept from this state to obtain a single I d V g data (transport properties). In Fig. 3, the solid lines represent the I dV g The TCR curve shows the TCR value at each gate voltage value calculated based on the data. The TCR curve shown by the solid line is the I d V g Data and I under different temperature conditions of 303K d V g The calculation is based on the data. The first upper limit of the gate voltage is the drain current I d is the gate voltage indicated by line U in FIG. 3 at point Mi where is the minimum. The first lower limit of the gate voltage is a gate voltage that satisfies the relationship of the following equations (1) and (2), such as the line L shown in FIG. 3. Here, the argmax function is a variable when the maximum value is achieved. In terms of equation (1), |dlog|I total (V g )| / dV g V when | achieves its maximum value g The current flowing through bolometer 1 is I total Then, the gate voltage value that maximizes the absolute value of TCR is a single I d V g It can be estimated from the data (transport properties). total is the drain current I d and V g is the gate voltage, and the calculated median value represents the gate voltage value at which the absolute value of TCR is maximized. The median value of the gate voltage shown by equation (1) is the gate voltage value shown by line C, which will be described later. As shown in FIG. 3, the line L is symmetrical with the line U with respect to the line C.

[0024]

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[0025] In FIG. 4, the solid line represents the TCR values, transcribed from FIG. In FIG. 4, the dashed line indicates the Id V g dlog|I calculated from the data total (V g )| / dV g It is. As shown in Figure 4, the gate voltage at which the absolute value of TCR is maximum and argmax|dlog|I total (V g )| / dV g The gate voltage of | and coincide at the gate voltage shown by line C.

[0026] For example, in the bolometer 1, when the drain voltage is negative, the gate voltage may be set between a second upper limit value and a second lower limit value, which will be described later. Moreover, the second upper limit may be set based on the median value of the gate voltage. Furthermore, a second lower limit may be set based on the median value of the gate voltage. The second upper limit value is a gate voltage that satisfies the relationship of equation (3), such as line UH shown in FIG. In this case, the second lower limit is a gate voltage that satisfies the relationship of equation (4), such as line LH shown in FIG.

[0027] Second upper limit = median + (upper limit - median) / 2 ... formula (3) Second lower limit = Second upper limit - (Second upper limit - Median) x 2 ... Formula (4)

[0028] (Detection method) An example of a method for detecting infrared rays using the bolometer 1 of the present disclosure will be described. An example of a method for detecting infrared rays using the bolometer 1 of the present disclosure is carried out according to the flow shown in FIG.

[0029] First, an operator applies a negative drain voltage to the drain electrode 14 (ST11). Specifically, the worker applies a negative drain voltage to a bolometer that includes a gate electrode 12, a drain electrode 14, a source electrode 15, and a first film 16 that connects the drain electrode 14 and the source electrode 15 and contains carbon nanotubes.

[0030] Next, the operator determines a first upper limit value of the gate voltage (ST12). The first upper limit is the gate voltage when the drain current of the drain electrode 14 is at a minimum. The operator sweeps the gate voltage in a predetermined range from the state in which the drain voltage is applied in ST11, and obtains the transport characteristics indicating the drain current values ​​obtained at each gate voltage value. Next, the operator obtains the gate voltage at which the drain current of the drain electrode 14 is minimum from the transport characteristics, and determines this gate voltage as the first upper limit value.

[0031] Next, the operator calculates the median value of the gate voltage (ST13). The worker calculates the median gate voltage using the above-mentioned formula (1).

[0032] Next, the operator calculates the first lower limit value of the gate voltage (ST14). The first lower limit is a gate voltage that satisfies the relationship of formulas (1) and (2). The operator calculates the first lower limit value from the median value of the calculated gate voltages.

[0033] Next, the worker applies a gate voltage between the first upper limit value and the first lower limit value to the gate electrode 12 (ST15). By applying a gate voltage between the first upper limit value and the first lower limit value, the operator can apply a gate voltage close to the gate voltage value at which the absolute value of the TCR is maximum.

[0034] Next, the operator detects infrared rays with the bolometer 1 (ST16). Here, infrared rays are detected in a state where the absolute value of TCR can be maximized by the gate voltage value applied by ST15. (Complete)

[0035] (Action and Effects) According to the bolometer 1 of the present disclosure, by applying a gate voltage between the first upper limit value and the first lower limit value, it is possible to apply a gate voltage close to the gate voltage at which the absolute value of the TCR is maximum. Therefore, the bolometer 1 of the present disclosure is prone to high TCR.

[0036] As a comparative example, a bolometer having an electric double layer transistor structure is given. One advantage of adopting an electric double-layer transistor structure is that it enables carrier control with a low gate voltage, but it also has many challenges. For example, electrolyte materials for electric double-layer transistors include ionic liquids, water with dissolved salts, organic solvents, and ion gels that contain them, but these are difficult to miniaturize, which makes it difficult to fabricate an array of bolometers. In addition, the potential window of the electrolyte is only a few volts, which limits the voltage that can be applied. Therefore, application of an excessive gate voltage causes degradation of the electrolyte, which makes the material susceptible to degradation.

[0037] In contrast to the comparative example, in the bolometer 1 of the present disclosure, the CNT network can be used as the bolometer resistor while controlling the gate voltage to be close to the gate voltage at which the absolute value of the TCR is maximized. This makes it easier to achieve a high TCR, and is expected to improve the detection ability of the bolometer. Furthermore, the components of the bolometer 1 of the present disclosure can be manufactured using conventional semiconductor processes, and therefore problems with miniaturization and material degradation as seen in the comparative example are unlikely to occur.

[0038] In addition, in the present disclosure, it has been confirmed that the greater the slope of the transport property data, the greater the absolute value of the TCR, as shown in FIG. FIG. 6 shows the I d V g The TCR (vertical axis) calculated based on the data and the slope of the transport property data |dlog|I total (V g )| / dV g | (horizontal axis) and the relationship between | and . The greater the gradient of the transport property data, the greater the absolute value of TCR, and a correlation can be confirmed. That is, I d V g It can be said that the greater the slope of the data, the larger the TCR tends to be. In the CNT-TFT, the hole current (I d V g The current (I in Figures 2 and 3) is the current on the negative side of the minimum current value in the data. d V g When comparing the hole current with the current on the positive side of the point where the current value is minimum in the data, the hole current is I d V g In many cases, the slope of the curve is steep. Therefore, it is thought that the point where the absolute value of TCR is maximized tends to be located on the negative side of the point where the current is minimum.

[0039] The bolometer 1 of the present disclosure "comprises a gate electrode 12 to which a gate voltage can be applied, a drain electrode 14 to which a drain voltage can be applied, a source electrode 15, and a first film 16 connecting the drain electrode 14 and the source electrode 15 and including a carbon nanotube 161, and when the drain voltage is negative, the gate voltage is set between a first upper limit value and a first lower limit value, the first upper limit value being the gate voltage at which the drain current of the drain electrode 14 is minimum, and the first lower limit value being a gate voltage that satisfies the relationship between equations (1) and (2)," thereby achieving the following effects. The bolometer 1 of the present disclosure can obtain the effect that "by applying a gate voltage between the first upper limit value and the first lower limit value, it is possible to apply a gate voltage close to the gate voltage at which the absolute value of the TCR is maximized." Therefore, the bolometer 1 of the present disclosure can easily have a high TCR.

[0040] In addition, in the bolometer 1 of the present disclosure, since "the carbon nanotubes are semiconducting carbon nanotubes", an effect can be obtained that "the absolute value of the TCR of the bolometer 1 can be improved".

[0041] In addition, in the bolometer 1 of the present disclosure, the first film 16 covers the drain electrode 14 and the source electrode 15, which has the effect of increasing the contact area between the CNTs 161 in the CNT network and the drain electrode 14 or the source electrode 15, thereby reducing the resistance of the bolometer 1.

[0042] The order of the steps disclosed above can be changed as appropriate. For example, the order of the steps of the detection method (steps S11 to S14) may be changed. For example, the first upper limit, the median, and the first lower limit of the gate voltage may be determined from the predicted characteristic data and the TCR curve acquired in advance (ST12-ST14), then a negative drain voltage may be applied (ST11), and then ST15-ST16 may be performed.

[0043] For example, the insulating film 13 disclosed above may be substantially doped with respect to the first film 16 . For example, when a fixed charge exists in the insulating layer 13 disclosed above, a situation where a gate voltage is effectively applied to the bolometer 1 is reproduced, and N-type doping may be substantially performed. In this case, an operator may perform P-type doping by using the second film 17, and move the minimum value of the TCR curve to the vicinity of a gate voltage of 0 V. For example, silicon nitride is an example of the insulating layer 13 having a fixed charge.

[0044] The above disclosure discloses that, from a state in which a negative drain voltage is applied to the drain electrode 14 of the bolometer 1, a gate voltage between a first upper limit value and a first lower limit value is applied to the gate electrode 12, so that a gate voltage can be applied close to the gate voltage at which the absolute value of the TCR is maximum. In contrast, in the bolometer 100 disclosed below, the gate electrode 12 and the source electrode 15 are short-circuited, and the bolometer 100 can be driven at a gate voltage of 0 V. The doping or undoping action of the second film 17B moves the minimum value of the TCR curve to the vicinity of a gate voltage of 0 V, which makes it easier to maximize the absolute value of the TCR when the bolometer 100 is driven at a gate voltage of 0 V. The undoping action here refers to a general term for the action of canceling P-type doping caused by oxygen and water adsorbed to the CNT. An example of the configuration of a bolometer according to the present disclosure will be described below with reference to FIGS. In addition, components common to those disclosed above are given the same reference numerals and detailed explanations are omitted.

[0045] (Bolometer configuration) As shown in FIG. 7, the bolometer 100 includes a substrate 11, a gate electrode 12, an insulating layer 13, a drain electrode 14, a source electrode 15, a first film 16B, a second film 17B, and an infrared absorbing layer 20, and further includes a short-circuit member 18.

[0046] (Second membrane 17B) The second film 17B contains a low molecular weight material or a high molecular weight material as a material that performs a doping or dedoping action. For example, the second film 17B may include P4VP or P4VBM. For example, the second film 17B may include a polymer material (e.g., P4VP or P4VBM) in which N-DMBI (4-(2,3-dihydro1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI), a low molecular weight material known to perform N-type doping, is dispersed. In addition, the low molecular weight material is not limited to N-DMBI, and various materials may be selected as long as stable doping is performed. For example, P4VP or P4VP having N-DMBI dispersed therein performs P-type dedoping or N-type doping on CNTs 161B contained in first film 16B. For example, P4VBM or P4VBM with N-DMBI dispersed therein performs P-type dedoping or N-type doping on CNTs 161B contained in first film 16B. In FIG. 8-FIG. 9, the first upper limit, the median, and the first lower limit of the gate voltage of the first film 16B including the CNTs 161B that have been dedoped from P-type or doped to N-type by P4VP are as follows. The graphs in FIG. 8-FIG. 9 show the relationship between the bolometer 100 and a given drain voltage (V d =-0.1V). The first upper limit of the gate voltage is the drain current I d is the gate voltage indicated by line UB in FIG. 8 at point MiB where is the minimum. The median value of the gate voltage is the gate voltage value indicated by the line CB in Fig. 8. As shown in Fig. 9, the gate voltage at which the absolute value of TCR is maximum and argmax|dlog|I total (V g )| / dV g The gate voltage of | coincides with the gate voltage indicated by line CB. The gate voltage value indicated by line CB is close to 0V. The first lower limit of the gate voltage is a gate voltage that satisfies the relationship of formulas (1) and (2) as shown by line LB in Fig. 8. Line LB is symmetrical to line UB with respect to line CB.

[0047] (Short circuit component) The short-circuit member 18 shorts the gate electrode 12 and the source electrode 15 . The short-circuit member 18 makes the potential of the gate electrode 12 equal to the potential of the source electrode 15. For example, in the case of the source electrode 15 disclosed above, the gate voltage is 0V.

[0048] (Manufacturing method) An example of a method for manufacturing the bolometer 100 of the present disclosure will be described. An example of a method for manufacturing the bolometer 100 of the present disclosure is carried out according to the flow shown in FIG.

[0049] First, an operator connects the drain electrode 14 and the source electrode 15, and laminates the first film 16B including carbon nanotubes (ST21).

[0050] Next, the worker provides a second film 17B on the surface of the first film 16B, which performs a P-type undoping action or an N-type doping action on the first film 16B (ST22). In ST22, the worker provides the second film 17B so that when the drain voltage applied to the drain electrode 14 is negative, the gate voltage (which is 0 V) ​​applied to the gate electrode 12 is set between the first upper limit value and the first lower limit value. The first upper limit is the gate voltage when the drain current of the drain electrode 14 is at a minimum, and the first lower limit is the gate voltage that satisfies the relationship of formulas (1) and (2). At this point, the bolometer 100 to which a predetermined voltage is applied is manufactured by the gate electrode 12 having the same potential as the source electrode 15. (Complete)

[0051] (Action and Effects) According to the bolometer 100 of the present disclosure, by applying a gate voltage between the first upper limit value and the first lower limit value, it is possible to drive the bolometer 100 near the gate voltage at which the absolute value of the TCR is maximized. Furthermore, the bolometer 100 of the present disclosure can be driven at a gate voltage of 0 V by the gate electrode 12 having the same potential as the source electrode 15 connected to GND. By performing P-type undoping or N-type doping on the second film 17B, the minimum value of the TCR curve is shifted to the vicinity of a gate voltage of 0 V. This makes it easier to maximize the absolute value of the TCR when the bolometer 100 is driven at a gate voltage of 0 V. Thus, the bolometer 100 of the present disclosure is prone to high TCR.

[0052] For example, as a modified example of the method for manufacturing the bolometer 100 of the present disclosure, an operator may perform a step of short-circuiting the gate electrode and the source electrode before ST21. For example, the worker may use a short-circuit member 18 to short-circuit the gate electrode 12 and the source electrode 15 .

[0053] (Changes in TCR curve) The TCR curve is considered to exist in the positive (negative) direction of the gate voltage depending on the conditions, compared to the TCR curve obtained in a vacuum. For example, the TCR curve changes depending on whether the drain voltage applied to the bolometer 100 is positive (negative) or whether the doping of the first film 16B is P-type (undoping from P-type or N-type doping). As disclosed above, when a gate voltage value in the vicinity of a specific voltage (hereinafter referred to as a "specific gate voltage value") is applied, the TCR curve has a minimum value. For example, assume that the specific gate voltage value at which the TCR curve obtained in a vacuum has a minimum value is 0V. When the bolometer 100 is operated in a vacuum, the absolute value of the TCR can be maximized at a specific gate voltage value of 0V. The specific gate voltage value may also vary slightly from 0V depending on the work function of the gate electrode, etc. Here, the "doping effect" of the second film 17B (or the above-mentioned second film 17) will be described in detail with reference to FIG. For example, the second film 17B contains P4VP, which performs P-type dedoping or N-type doping on the CNTs 161 contained in the first film 16. FIG. 11 shows the transport characteristics of a bolometer 100 having a CNT network in the first film 16B, in which the CNTs 161B are N-doped. For example, FIG. 11 shows a comparison of the TCR curve of P-type doping in FIG. 2 with the TCR curve of P-type dedoping or N-type doping. The transport characteristics and TCR curves of P-type dedoping or N-type doping in FIG. 11 are obtained under the same conditions as FIG. 2. Here, the transport characteristics and TCR curves of P-type doping are shown by thin lines. Also, the transport characteristics and TCR curves of P-type dedoping or N-type doping are shown by thick lines. It can be seen that, compared to the TCR curve for P-type doping (thin solid line), the TCR curve for P-type de-doping or N-type doping (thick solid line) exists in the negative direction of the gate voltage.

[0054] Also, CNTs are inherently electrically neutral. However, for example, in an atmospheric environment, CNTs 161B may be P-type doped with water or oxygen. Thus, first film 16B including CNTs 161B may be P-type doped with water or oxygen. When second film 17B is not provided, transport characteristics and TCR curves of first film 16B including CNTs 161B that are P-type doped with water or oxygen show similar trends to those shown in the graph of FIG. 2. From the above, for example, the TCR curve can be shifted by dedoping from P type or doping from N type to CNT 161B that has already been doped with P type by the second film 17B. In this case, the second film 17B may be used to dedope from P type or dope from N type, and the minimum value of the TCR curve may be brought to the vicinity of a gate voltage of 0V. As a result, when driven with a gate voltage of 0V, the shifted TCR curve takes a value close to the minimum value. Therefore, when driven with a gate voltage of 0V, the absolute value of the TCR can be maximized, and the detection performance of the bolometer 100 is improved. In this way, the operator can create a situation close to that when the bolometer 100 is operated in a vacuum.

[0055] The bolometer 100 of the present disclosure is "a bolometer comprising a gate electrode 12 to which a gate voltage can be applied, a drain electrode 14 to which a drain voltage can be applied, a source electrode 15, a first film 16B connecting the drain electrode 14 and the source electrode 15 and including a carbon nanotube 161B, and a second film 17B provided on the surface of the first film 16B and performing a doping effect on the first film 16B, in which, when the drain voltage is negative, the gate voltage is set between a first upper limit value and a first lower limit value, the first upper limit value being the gate voltage when the drain current of the drain electrode 14 is minimum, and the first lower limit value being a gate voltage having the relationship between equations (1) and (2)", and thereby the following effects can be obtained. The bolometer 100 of the present disclosure can achieve the following effect: "The TCR curve can be shifted. As a result, by setting the gate voltage at which the absolute value of the TCR is maximized to be close to a predetermined voltage value, the bolometer 100 can be driven at a gate voltage close to which the absolute value of the TCR is maximized."

[0056] Furthermore, in the bolometer 100 of the present disclosure, the gate electrode 12 and the source electrode 15 are short-circuited, which provides the following effect. The bolometer 100 of the present disclosure can be driven at a gate voltage of 0 V by the gate electrode 12 having the same potential as the source electrode 15 connected to GND. By de-doping the second film 17B from P-type or doping it into N-type, the minimum value of the TCR curve can be moved to the vicinity of a gate voltage of 0 V, which makes it easier to maximize the absolute value of the TCR when the bolometer 100 is driven at a gate voltage of 0 V.

[0057] For example, the second film 17B disclosed above may be appropriately selected as necessary so as to maximize the absolute value of the TCR at a set gate voltage. Two examples are given below. For example, when the bolometer 100 is in a vacuum, the absolute value of the TCR may be maximized near 0 V. In this case, if there is no need to shift the TCR curve, the operator does not need to select the second film 17B to be doped with P-type doping. For example, in an atmospheric environment, CNT 161B may be P-type doped with water or oxygen, and may also be substantially N-type doped due to the fixed charge of insulating layer 13. In this case, if the absolute value of TCR can be maximized near 0 V, the operator may determine that there is no need to shift the TCR curve, and may not select second film 17B to be P-type doped.

[0058] An example of the configuration of a bolometer according to the present disclosure will be described below with reference to FIG.

[0059] (composition) The bolometer 1Z includes a gate electrode 12Z to which a gate voltage can be applied, a drain electrode 14Z to which a drain voltage can be applied, a source electrode 15Z, and a first film 16Z connecting the drain electrode 14Z and the source electrode and including a carbon nanotube 161Z, and when the drain voltage is negative, the gate voltage is set between a first upper limit value and a first lower limit value, the first upper limit value being the gate voltage at which the drain current of the drain electrode 14 is minimum, and the first lower limit value being the gate voltage that satisfies the relationship between equations (1) and (2).

[0060] (Action and Effects) According to the bolometer 1Z of the present disclosure, by applying a gate voltage between the first upper limit value and the first lower limit value, it is possible to apply a gate voltage close to the gate voltage at which the absolute value of the TCR is maximum. Therefore, the bolometer 1Z of the present disclosure is prone to high TCR.

[0061] An example of the detection method according to the present disclosure will now be described with reference to FIG. An example of the detection method according to the present disclosure is carried out according to the flow shown in FIG.

[0062] The detection method includes applying a negative drain voltage to the drain electrode of a bolometer having a gate electrode, a drain electrode, a source electrode, and a first film connecting the drain electrode and the source electrode and containing carbon nanotubes (ST31), applying a gate voltage between a first upper limit value and a first lower limit value to the gate electrode (ST32), and detecting infrared rays (ST33), where the first upper limit value is the gate voltage when the drain current of the drain electrode is at a minimum, and the first lower limit value is the gate voltage that satisfies the relationship between equations (1) and (2).

[0063] (Action and Effects) According to the detection method of the present disclosure, by applying a gate voltage between the first upper limit value and the first lower limit value, it is possible to apply a gate voltage close to the gate voltage at which the absolute value of the TCR is maximum. Thus, the detection methods of the present disclosure are amenable to high TCR.

[0064] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-mentioned embodiments. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be appropriately combined with other embodiments.

[0065] A part or all of the above-described embodiments can be described as, but is not limited to, the following supplementary notes.

[0066] (Appendix 1) a gate electrode to which a gate voltage can be applied; a drain electrode to which a drain voltage can be applied; A source electrode; a first film connecting the drain electrode and the source electrode and including carbon nanotubes; Equipped with When the drain voltage is negative, the gate voltage is set between a first upper limit and a first lower limit; the first upper limit is the gate voltage when a drain current of the drain electrode becomes a minimum, The first lower limit is the gate voltage that satisfies the relationship of formula (1) and formula (2). Bolometer.

number

[0067] (Appendix 2) a second film provided on a surface of the first film and performing a doping action on the first film; Further equipped 2. A bolometer as described in appended claim 1.

[0068] (Appendix 3) The gate electrode and the source electrode are short-circuited. A bolometer as described in appended note 2.

[0069] (Appendix 4) When the drain voltage is negative, the gate voltage is set between a second upper limit and a second lower limit; The second upper limit satisfies the relationship of formula (3), The second lower limit value satisfies the relationship of formula (4). 4. A bolometer according to any one of claims 1 to 3. Second upper limit = median + (first upper limit - median) / 2 ... formula (3) Second lower limit = Second upper limit - (Second upper limit - Median) x 2 ... Formula (4)

[0070] (Appendix 5) The second film comprises a polymeric material. 4. A bolometer according to claim 2 or 3.

[0071] (Appendix 6) The second film comprises PMMA, P4VP, or P4VBM. 4. A bolometer according to claim 2 or 3.

[0072] (Appendix 7) The carbon nanotubes are semiconducting carbon nanotubes. 3. A bolometer according to claim 1 or 2.

[0073] (Appendix 8) The first film covers the drain electrode and the source electrode. 3. A bolometer according to claim 1 or 2.

[0074] (Appendix 9) A bolometer including a gate electrode, a drain electrode, a source electrode, and a first film connecting the drain electrode and the source electrode and including a carbon nanotube, applying a negative drain voltage to the drain electrode; applying a gate voltage between a first upper limit value and a first lower limit value to the gate electrode; Detects infrared rays, the first upper limit is the gate voltage when a drain current of the drain electrode becomes a minimum, The first lower limit is the gate voltage that satisfies the relationship of formula (1) and formula (2). Detection methods.

number

[0075] (Appendix 10) In the step of applying the gate voltage, When the drain voltage is negative, the gate voltage is set between a second upper limit and a second lower limit; The second upper limit satisfies the relationship of formula (3), The second lower limit value satisfies the relationship of formula (4). The detection method described in Appendix 8. Second upper limit = median + (first upper limit - median) / 2 ... formula (3) Second lower limit = Second upper limit - (Second upper limit - Median) x 2 ... Formula (4)

[0076] (Appendix 11) A drain electrode and a source electrode are connected, and a first film containing carbon nanotubes is laminated thereon; providing a second film on a surface of the first film for performing a doping action on the first film; In the step of providing the second film, when a drain voltage applied to the drain electrode is negative, a gate voltage applied to the gate electrode is set between a first upper limit value and a first lower limit value; the first upper limit is the gate voltage when a drain current of the drain electrode becomes a minimum, The second film is provided so that the first lower limit is the gate voltage that satisfies the relationship of formulas (1) and (2). Bolometer manufacturing method.

number

[0077] (Appendix 12) When the drain voltage is negative, the gate voltage is set between a second upper limit and a second lower limit; In the step of applying the gate voltage, The second upper limit satisfies the relationship of formula (3), The second lower limit value satisfies the relationship of formula (4). 12. A method for manufacturing a bolometer as described in claim 11. Second upper limit = median + (upper limit - median) / 2 ... formula (3) Second lower limit = Second upper limit - (Second upper limit - Median) x 2 ... Formula (4)

[0078] (Appendix 13) In the step of providing the second film, The second film comprises a polymeric material. 13. A method for manufacturing a bolometer according to claim 11 or 12.

[0079] (Appendix 14) In the step of providing the second film, The second film comprises PMMA, P4VP, or P4VBM. 14. A method for manufacturing a bolometer according to any one of claims 11 to 13.

[0080] (Appendix 15) In the step of laminating the first film, The carbon nanotubes are semiconducting carbon nanotubes. 15. A method for manufacturing a bolometer according to any one of claims 11 to 14.

[0081] (Appendix 16) In the step of laminating the first film, The first film covers the drain electrode and the source electrode. 16. A method for manufacturing a bolometer according to any one of claims 11 to 15. [Explanation of symbols]

[0082] 1 Bolometer 11 Substrate 12 Gate electrode 13 Insulating layer 14 Drain electrode 15 Source electrode 16 First membrane 161 Carbon Nanotubes 17 Second membrane 1B Bolometer 16B First membrane 161B Carbon nanotubes 17B Second membrane 1Z Bolometer 12Z Gate electrode 14Z Drain electrode 15Z Source electrode 16Z First membrane 161Z Carbon Nanotube 100 bolometers 18 Short circuit member

Claims

1. a gate electrode to which a gate voltage can be applied; a drain electrode to which a drain voltage can be applied; A source electrode; a first film connecting the drain electrode and the source electrode and including carbon nanotubes; Equipped with When the drain voltage is negative, the gate voltage is set between a first upper limit and a first lower limit; the first upper limit is the gate voltage when a drain current of the drain electrode becomes a minimum, The first lower limit is the gate voltage that satisfies the relationship of formula (1) and formula (2). Bolometer. [0010] First lower limit value = First upper limit value - (First upper limit value - Median value) x 2 ... Formula (2)

2. a second film provided on a surface of the first film and performing a doping action on the first film; Further equipped 2. The bolometer of claim 1.

3. The gate electrode and the source electrode are short-circuited.

3. The bolometer of claim 2.

4. When the drain voltage is negative, the gate voltage is set between a second upper limit and a second lower limit; The second upper limit satisfies the relationship of formula (3), The second lower limit value satisfies the relationship of formula (4). A bolometer according to any one of claims 1 to 3. Second upper limit value=median value+(first upper limit value-median value) / 2...Equation (3) Second lower limit value=Second upper limit value−(Second upper limit value−Median value)×2...Equation (4)

5. The second membrane comprises a polymeric material. A bolometer according to claim 2 or 3.

6. The second film comprises PMMA, P4VP, or P4VBM. A bolometer according to claim 2 or 3.

7. The carbon nanotubes are semiconducting carbon nanotubes.

3. A bolometer according to claim 1 or 2.

8. The first film covers the drain electrode and the source electrode.

3. A bolometer according to claim 1 or 2.

9. A bolometer including a gate electrode, a drain electrode, a source electrode, and a first film connecting the drain electrode and the source electrode and including a carbon nanotube, applying a negative drain voltage to the drain electrode; applying a gate voltage between a first upper limit value and a first lower limit value to the gate electrode; Detects infrared rays, the first upper limit is the gate voltage when a drain current of the drain electrode becomes a minimum, The first lower limit is the gate voltage that satisfies the relationship of formula (1) and formula (2). Detection methods. [0010] First lower limit value = First upper limit value - (First upper limit value - Median value) x 2 ... Formula (2)

10. A drain electrode and a source electrode are connected, and a first film containing carbon nanotubes is laminated thereon; providing a second film on a surface of the first film for performing a doping action on the first film; In the step of providing the second film, when a drain voltage applied to the drain electrode is negative, a gate voltage applied to the gate electrode is set between a first upper limit value and a first lower limit value; the first upper limit is the gate voltage when a drain current of the drain electrode becomes a minimum, The second film is provided so that the first lower limit is the gate voltage that satisfies the relationship of formulas (1) and (2). Bolometer manufacturing method. [0010] First lower limit value = First upper limit value - (First upper limit value - Median value) x 2 ... Formula (2)

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