Electromagnetic wave detector and array of electromagnetic wave detectors

Abstract

An electromagnetic wave detection device includes: a semiconductor layer (4); a two-dimensional material layer (1) electrically connected to the semiconductor layer; a first electrode portion (2a) electrically connected to the two-dimensional material layer without passing through the semiconductor layer; a second electrode portion (2b) electrically connected to the two-dimensional material layer via the semiconductor layer (4); and a ferroelectric layer (5) in contact with at least a portion of the two-dimensional material layer.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an electromagnetic wave detector and an electromagnetic wave detector array. BACKGROUND

[0002] In the past, as a material of an electromagnetic wave detection layer used in a next-generation electromagnetic wave detector, graphene, which is one example of a two-dimensional material layer, having extremely high mobility, has been known. The absorption rate of graphene is as low as 2.3%. Therefore, a high-sensitivity method in an electromagnetic wave detector using graphene has been proposed. For example, in U.S. Patent Application Publication No. 2015 / 0243826 (Patent Literature 1), a detector having the following configuration is proposed. That is, in the detector of the above-described Patent Literature 1, two or more dielectric layers are provided on an n-type semiconductor layer. A graphene layer is formed on the two dielectric layers and on a surface portion of the n-type semiconductor layer located between the two dielectric layers. The graphene layer and the n-type semiconductor layer are Schottky-joined. A source electrode / drain electrode connected to both ends of the graphene layer is disposed on the dielectric layer. A gate electrode is connected to the n-type semiconductor layer. In a case where a voltage is applied between the gate electrode and the source electrode or the drain electrode, a breaking operation can be performed by the above-described Schottky-joining.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: U.S. Patent Application Publication No. 2015 / 0243826 SUMMARY

[0006] However, regarding a state in which a voltage is applied between the gate electrode and the source electrode or the drain electrode, the sensitivity of the detector depends on the quantum efficiency of the semiconductor layer. Therefore, photo-carriers cannot be sufficiently amplified, and it is difficult to achieve high sensitivity of the detector.

[0007] The main object of the present disclosure is to provide an electromagnetic wave detector and an electromagnetic wave detector array having higher detection sensitivity than the above-described detector.

[0008] The electromagnetic wave detector according to the present disclosure includes a semiconductor layer, a two-dimensional material layer electrically connected to the semiconductor layer, a first electrode portion electrically connected to the two-dimensional material layer without passing through the semiconductor layer, a second electrode portion electrically connected to the two-dimensional material layer via the semiconductor layer, and a ferroelectric layer in contact with at least a portion of the two-dimensional material layer.

[0009] According to the present disclosure, it is possible to provide an electromagnetic wave detector and an electromagnetic wave detector array having higher detection sensitivity than the above-described detector. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1is a schematic plan view of the electromagnetic wave detector according to Embodiment 1.

[0011] Figure 2 is a schematic cross-sectional view along the line segment II-II of Figure 1

[0012] Figure 3 is a flowchart for explaining a manufacturing method of the electromagnetic wave detector according to Embodiment 1.

[0013] Figure 4 is a schematic plan view of the electromagnetic wave detector according to Embodiment 2.

[0014] Figure 5 is a schematic cross-sectional view along the line segment V-V of Figure 4

[0015] Figure 6 is a schematic cross-sectional view showing a first modification of the electromagnetic wave detector according to Embodiment 2.

[0016] Figure 7 is a schematic cross-sectional view showing a second modification of the electromagnetic wave detector according to Embodiment 2.

[0017] Figure 8 is a schematic plan view of the electromagnetic wave detector according to Embodiment 3.

[0018] Figure 9 is a schematic cross-sectional view along the line segment IX-IX of Figure 8

[0019] Figure 10 is a schematic plan view of the electromagnetic wave detector according to Embodiment 4.

[0020] Figure 11 is a schematic cross-sectional view along the line segment XI-XI of Figure 10

[0021] Figure 12 is a schematic plan view showing a first modification of the electromagnetic wave detector according to Embodiment 4.

[0022] Figure 13 is a schematic cross-sectional view along the line segment XIII-XIII of Figure 12

[0023] Figure 14 is a schematic plan view showing a second modification of the electromagnetic wave detector according to Embodiment 4.

[0024] Figure 15 is a schematic cross-sectional view along the line segment XV-XV of Figure 14

[0025] ​​​​​​Figure 16 is a cross-sectional view of the electromagnetic wave detector according to Embodiment 5.

[0026] Figure 17 is a plan view of a modification of the electromagnetic wave detector according to Embodiment 5.

[0027] Figure 18 is a cross-sectional view along line segment XVIII-XVIII of Figure 17 .

[0028] Figure 19 is a cross-sectional view of the electromagnetic wave detector according to Embodiment 7.

[0029] Figure 20 is a cross-sectional view of the electromagnetic wave detector according to Embodiment 8.

[0030] Figure 21 is a cross-sectional view of the electromagnetic wave detector according to Embodiment 9.

[0031] Figure 22 is a plan view of the electromagnetic wave detector according to Embodiment 10.

[0032] Figure 23 is a cross-sectional view along line segment XXIII-XXIII of Figure 22 .

[0033] Figure 24 is a cross-sectional view along line segment XXIV-XXIV of Figure 22 .

[0034] Figure 25 is a plan view of a first modification of the electromagnetic wave detector according to Embodiment 10.

[0035] Figure 26 is a cross-sectional view along line segment XXVI-XXVI of Figure 25 .

[0036] Figure 27 is a plan view of a second modification of the electromagnetic wave detector according to Embodiment 10.

[0037] Figure 28 is a cross-sectional view along line segment XXVIII-XXVIII of Figure 27 .

[0038] Figure 22 is a cross-sectional view of the electromagnetic wave detector according to Embodiment 11.

[0039] Figure 1 is a cross-sectional view of a modification of the electromagnetic wave detector according to Embodiment 11.

[0040] Figure 2 is a cross-sectional view of an electromagnetic wave detector according to Embodiment 12.

[0041] Figure 1 is a cross-sectional view of a modification of the electromagnetic wave detector according to Embodiment 12.

[0042] Figure 1 is a cross-sectional view of an electromagnetic wave detector according to Embodiment 14.

[0043] Figure 2 is a cross-sectional view of an electromagnetic wave detector according to Embodiment 15.

[0044] Figure 1 is a cross-sectional view of an electromagnetic wave detector according to Embodiment 16.

[0045] Figure 2 is a cross-sectional view of a modification of the electromagnetic wave detector according to Embodiment 16.

[0046] Figure 1 is a cross-sectional view of an electromagnetic wave detector according to Embodiment 17.

[0047] Figure 2 is a plan view of an electromagnetic wave detector according to Embodiment 18.

[0048] Figure 2 is a plan view of a modification of the electromagnetic wave detector according to Embodiment 18.

[0049] (Symbol Explanation)

[0050] 1: two-dimensional material layer; 2a: first electrode portion; 2b, 2ba: second electrode portion; 2bb: fourth electrode portion; 2c: third electrode portion; 2d: connecting conductor portion; 3, 3b: insulating film; 4, 4a, 4b: semiconductor layer; 5, 5a, 5b: ferroelectric layer; 6: tunnel insulating layer; 7: conductor; 8: contact layer; 9: void; 100, 200, 201, 202, 203: electromagnetic wave detector. DETAILED DESCRIPTION

[0051] Hereinafter, embodiments of the present disclosure will be described. Furthermore, the same structure will not be repeatedly described with the same reference numerals.

[0052] In the following embodiments described, the drawings are schematic drawings conceptually illustrating functions or configurations. In addition, the present disclosure is not limited to the following embodiments described. The basic structure of the electromagnetic wave detector is common in all embodiments except for cases specifically described. In addition, parts to which the same reference signs are attached are the same or comparable as described above. This is common throughout the specification.

[0053] In the following embodiments described, regarding the electromagnetic wave detector, the structure in which visible light or infrared light is detected is described, but the present disclosure is not limited to these. The embodiments described below are effective as a detector of an electric wave such as X-rays, ultraviolet light, near-infrared light, terahertz (THz) waves, or microwaves in addition to visible light or infrared light. Furthermore, in the embodiments of the present disclosure, these light and electric waves are collectively described as electromagnetic waves.

[0054] In addition, in the embodiments of the present disclosure, there are cases in which the term in which p-type graphene or n-type graphene is used as graphene is used. In the following embodiments, graphene in which holes are more than intrinsic state graphene is referred to as p-type graphene, and graphene in which electrons are more is referred to as n-type graphene.

[0055] In addition, in the embodiments of the present disclosure, regarding the material of a member that contacts graphene, which is one example of a two-dimensional material layer, there are cases in which the term in which n-type or p-type is used. Here, for example, an n-type material refers to a material having electron-donating properties, and a p-type material refers to a material having electron-accepting properties. In addition, there are cases in which a bias occurs in the charge in the entire molecule, and a case in which electrons become dominant is referred to as n-type, and a case in which holes become dominant is referred to as p-type. As these materials, either one of an organic substance and an inorganic substance or a mixture thereof can be used.

[0056] In addition, regarding a phenomenon referred to as virtual surface plasmon resonance in the sense of a resonance applied to a metal surface other than a surface plasmon resonance phenomenon and a plasmon resonance phenomenon, a visible light domain / near-infrared light domain, or a phenomenon referred to as a metamaterial or a plasmonic metamaterial in the sense of operating a specific wavelength by a structure of a size of a wavelength or less, they are not distinguished by names in particular, and are handled equally in terms of the effects of the phenomenon. Here, these resonances are referred to as surface plasmon resonance, plasmon resonance, or simply resonance.

[0057] In addition, in the embodiments described below, as the material of the two-dimensional material layer, graphene is described as an example, but the material constituting the two-dimensional material layer is not limited to graphene. For example, as the material of the two-dimensional material layer, a material such as a transition metal dichalcogenide (TMD), black phosphorus, silicene (a two-dimensional honeycomb structure based on silicon atoms), germanene (a two-dimensional honeycomb structure based on germanium atoms), or the like can be applied. As the transition metal dichalcogenide, for example, a transition metal dichalcogenide such as MoS2, WS2, WSe2, or the like can be given.

[0058] These materials have a similar structure to graphene and are materials that can arrange atoms in a single layer in a two-dimensional plane. Therefore, even in the case where these materials are applied to the two-dimensional material layer, the same effects as in the case where graphene is applied to the two-dimensional material layer can be obtained.

[0059] Embodiment 1

[0060] Structure of electromagnetic wave detector

[0061] Figure 2 is a top view schematic diagram of the electromagnetic wave detector according to Embodiment 1. Figure 2 is a cross-sectional view schematic diagram along the line segment II-II of Figure 2 Figure 2 The electromagnetic wave detector shown in Figure 2 The electromagnetic wave detector shown in Figure 2 In the electromagnetic wave detector shown in Figure 2

[0062] The semiconductor layer 4 has a first surface and a second surface on the side opposite to the first surface. As shown in Figure 2 Figure 2 ​​​As shown, the two-dimensional material layer 1, the first electrode portion 2a, the insulating film 3, and the ferroelectric layer 5 are disposed on the first surface of the semiconductor layer 4. The second electrode portion 2b is disposed on the second surface of the semiconductor layer 4. Hereinafter, on the first surface, the portion on the side opposite to the semiconductor layer 4 of each of the two-dimensional material layer 1, the first electrode portion 2a, the insulating film 3, and the ferroelectric layer 5 is referred to as an upper portion of each, and the portion on the side of the semiconductor layer 4 of each of the two-dimensional material layer 1, the first electrode portion 2a, the insulating film 3, and the ferroelectric layer 5 is referred to as a lower portion of each.

[0063] The semiconductor layer 4 is composed of, for example, a semiconductor material such as silicon (Si). Specifically, as the semiconductor layer 4, a silicon substrate doped with an impurity or the like is used.

[0064] Here, the semiconductor layer 4 can also be a multilayer structure, and a pn junction photodiode, a pin photodiode, a Schottky photodiode, or an avalanche photodiode can be used. In addition, a phototransistor can also be used as the semiconductor layer 4.

[0065] As the semiconductor material constituting the semiconductor layer 4, as described above, a silicon substrate is exemplified, but other materials can also be used as the material constituting the semiconductor layer 4. For example, as the material constituting the semiconductor layer 4, germanium (Ge), a compound semiconductor such as a Group III-V or Group II-V semiconductor, mercury cadmium telluride (HgCdTe), indium antimony (InSb), lead selenide (PbSe), lead sulfide (PbS), cadmium sulfide (CdS), gallium nitride (GaN), silicon carbide (SiC), gallium phosphide (GaP), indium gallium arsenide (InGaAs), indium arsenide (InAs), a substrate containing a quantum well or a quantum dot, a material of Type II superlattice, or a material composed of a combination of these materials can be used.

[0066] In the electromagnetic wave detector according to the present embodiment, it is preferable to dope the semiconductor layer 4 and the semiconductor layer 4 with an impurity in such a manner that the resistivity of the semiconductor layer 4 and the semiconductor layer 4 becomes 100 Ω·cm or less. By doping the semiconductor layer 4 and the semiconductor layer 4 with a high concentration, the moving speed (readout speed) of the carrier in the semiconductor layer 4 and the semiconductor layer 4 becomes fast. As a result, the response speed of the electromagnetic wave detector is improved.

[0067] In addition, the thickness T1 of the semiconductor layer 4 is preferably 10 μm or less. By thinning the thickness T1 of the semiconductor layer 4, the deactivation of the carrier becomes less.

[0068] As shown in FIG. 1, the electromagnetic wave detector 1 includes a two-dimensional material layer 1, a first electrode portion 2a, an insulating film 3, a semiconductor layer 4, a second electrode portion 2b, and a ferroelectric layer 5. Figure 3As shown, between the first electrode portion 2a and the second electrode portion 2b, a power supply circuit for applying a bias voltage V is electrically connected. The above-described power supply circuit is a circuit for applying a voltage V to the two-dimensional material layer 1. To the above-described power supply circuit, an unillustrated ammeter for detecting a current I in the two-dimensional material layer 1 is connected.

[0069] The insulating film 3 is disposed on the first surface of the semiconductor layer 4. The insulating film 3 has a lower surface in contact with the first surface of the semiconductor layer 4 and an upper surface on the side opposite to the lower surface. An opening portion exposing a part of the first surface of the semiconductor layer 4 is formed in the insulating film 3. The opening portion reaches from the upper surface to the lower surface. At least a part of the upper surface of the insulating film 3 is in contact with the lower surface of the two-dimensional material layer 1. In other words, the insulating film 3 is disposed on the lower portion of the two-dimensional material layer 1.

[0070] As the insulating film 3, for example, an insulating film composed of silicon oxide can be used. Further, the material constituting the insulating film 3 is not limited to the above-described silicon oxide, and other insulating materials can be used. For example, as the material constituting the insulating film 3, tetraethyl orthosilicate, silicon nitride, hafnium oxide, aluminum oxide, nickel oxide, boron nitride, or a siloxane-based polymer material, or the like can be used. For example, boron nitride has an atomic arrangement similar to that of graphene, and therefore, even if it is in contact with the two-dimensional material layer 1 composed of graphene, it does not adversely affect the mobility of charges. Therefore, from the viewpoint of suppressing the insulating film 3 from hindering the performance of the two-dimensional material layer 1 such as electron mobility, boron nitride is preferable as the material constituting the insulating film 3.

[0071] Further, regarding the thickness T2 of the insulating film 3, that is, the distance between the lower surface and the upper surface of the insulating film 3, there is no particular limitation as long as the first electrode portion 2a is insulated from the semiconductor layer 4 and does not generate a tunnel current. Further, the insulating film 3 can not be disposed on the lower portion of the two-dimensional material layer 1.

[0072] The first electrode portion 2a is disposed on the upper surface of the insulating film 3. The first electrode portion 2a is disposed at a position apart from the opening portion of the insulating film 3. The first electrode portion 2a has a lower surface in contact with the upper surface of the insulating film 3, an upper surface on the side opposite to the lower surface, and a side surface extending in a direction intersecting the upper surface. The second electrode portion 2b is disposed on the second surface of the semiconductor layer 4. As a material constituting the first electrode portion 2a and the second electrode portion 2b, any material can be used as long as it is an electrical conductor. For example, as the material, a metallic material such as gold (Au), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), chromium (Cr), or palladium (Pd) can be used. In addition, an unillustrated adhesion layer can be formed between the first electrode portion 2a and the insulating film 3 or between the second electrode portion 2b and the semiconductor layer 4. The adhesion layer improves the adhesion of the first electrode portion 2a and the insulating film 3 or the adhesion of the second electrode portion 2b and the semiconductor layer 4. As a material constituting the adhesion layer, any material can be used, but for example, a metallic material such as chromium (Cr) or titanium (Ti) can be used.

[0073] In addition, in the electromagnetic wave detector shown in Figure 3 , the first electrode portion 2a is formed on the lower portion of the two-dimensional material layer 1, but the first electrode portion 2a can also be formed on the upper portion of the two-dimensional material layer 1. In addition, in the electromagnetic wave detector shown in Figure 1 , the second electrode portion 2b is provided on the entire surface of the second surface of the semiconductor layer 4, but the second electrode portion 2b can be in contact with at least a portion of the semiconductor layer 4. For example, the second electrode portion 2b can be provided so as to be in contact with a portion of the first surface, the second surface, and the side surface extending in a direction intersecting the first surface of the semiconductor layer 4. Such an electromagnetic wave detector can detect an electromagnetic wave incident from the second surface side. Furthermore, as shown in Figure 2 , the electromagnetic wave detector in which the second electrode portion 2b is provided on the entire surface of the second surface is preferable in the case where an electromagnetic wave incident only from the first surface side becomes a detection object. In the electromagnetic wave detector shown in Figure 3 , an electromagnetic wave incident from the first surface side and transmitted through the ferroelectric layer 5 and the semiconductor layer 4 is reflected by the second electrode portion 2b to reach the ferroelectric layer 5 again, so the absorption rate of the electromagnetic wave in the ferroelectric layer 5 is improved.

[0074] The two-dimensional material layer 1 is disposed on the first electrode portion 2a, the insulating film 3, and the semiconductor layer 4. The two-dimensional material layer 1 extends from the inside of the opening portion of the insulating film 3 to the first electrode portion 2a. A portion of the two-dimensional material layer 1 is disposed on the first electrode portion 2a in contact with the first electrode portion 2a. Another portion of the two-dimensional material layer 1 is disposed inside the opening portion of the insulating film 3 in contact with the semiconductor layer 4. The two-dimensional material layer 1 is disposed on the lower portion of the ferroelectric layer 5 in contact with the ferroelectric layer 5. The two-dimensional material layer 1 is disposed between the first electrode portion 2a, the insulating film 3, and the semiconductor layer 4 and the ferroelectric layer 5.

[0075] Specifically, the two-dimensional material layer 1 includes a first portion electrically connected to the semiconductor layer 4, a second portion electrically connected to the first electrode portion 2a, and a third portion electrically connecting the first portion and the second portion.

[0076] The first portion is disposed on the first surface of the semiconductor layer 4 within the opening of the insulating film 3. The first portion is disposed below the ferroelectric layer 5. The first portion is disposed between the semiconductor layer 4 and the ferroelectric layer 5, and is in contact with both the semiconductor layer 4 and the ferroelectric layer 5. Preferably, the first portion is Schottky bonded to the semiconductor layer 4.

[0077] The second part is disposed on the upper surface of the insulating film 3. A portion of the second part is disposed on the upper surface of the first electrode portion 2a. At least a portion of the second part is disposed on the lower part of the ferroelectric layer 5. The second part is disposed between the first electrode portion 2a and the ferroelectric layer 5, and is in contact with both the first electrode portion 2a and the ferroelectric layer 5.

[0078] The third portion is disposed on the upper surface of the insulating film 3 and on the inner peripheral surface of the opening of the insulating film 3. The third portion is disposed between the insulating film 3 and the ferroelectric layer 5, and is in contact with both the insulating film 3 and the ferroelectric layer 5. In other words, the insulating film 3 separates the third portion of the two-dimensional material layer 1 from the semiconductor layer 4.

[0079] The thicknesses of the first, second, and third portions of the two-dimensional material layer 1 are, for example, equal. Unevennesses caused by the first, second, and third portions are formed on the upper surface of the two-dimensional material layer 1. The distance between the upper surface of the first portion and the first surface of the semiconductor layer 4 is less than the distance between the upper surface of the second portion and the first surface of the semiconductor layer 4.

[0080] The two-dimensional material layer 1 includes a region in contact with the ferroelectric layer 5 and a region in contact with the semiconductor layer 4. The ferroelectric layer 5 is configured to generate an electric field in at least one of the regions of the two-dimensional material layer 1 in contact with the ferroelectric layer 5 and in contact with the semiconductor layer 4, in a direction perpendicular to the extension direction of the two-dimensional material layer 1.

[0081] also, Figure 1 The opening of the two-dimensional material layer 1 relative to the insulating film 3 is located from the center of the first electrode portion 2a side ( Figure 2 (left side) extends to its opposite side ( Figure 1 (to the right of), but not limited to. Figure 2 In this configuration, the end (right end) of the two-dimensional material layer 1 located on the side opposite to the first electrode portion 2a can also be positioned on the left side relative to the center of the opening of the insulating film 3. Furthermore, Figure 2The two-dimensional material layer 1 in the semiconductor device 100 is configured to expose a part of the first surface of the semiconductor layer 4 at the opening portion of the insulating film 3, but is not limited thereto. The two-dimensional material layer 1 can also be configured to cover the entire first surface of the semiconductor layer 4 at the opening portion of the insulating film 3. The end portion (right end) of the two-dimensional material layer 1 on the side opposite to the first electrode portion 2a can also be disposed on the insulating film 3 on the side opposite to the first electrode portion 2a with respect to the opening portion.

[0082] The two-dimensional material layer 1 can use, for example, single-layer graphene. The single-layer graphene is a single atomic layer of a two-dimensional carbon crystal. In addition, the single-layer graphene has carbon atoms at each chain configured in a hexagonal shape. In addition, the two-dimensional material layer 1 can be configured to stack two or more layers of graphene. In addition, as the two-dimensional material layer 1, undoped graphene or graphene doped with p-type or n-type impurities can be used.

[0083] In the case where the two-dimensional material layer 1 uses multi-layer graphene, the photoelectric conversion efficiency of the two-dimensional material layer 1 increases, and the sensitivity of the electromagnetic wave detector becomes higher. The multi-layer graphene used as the two-dimensional material layer 1 can have the same or different orientations of the lattice vectors of the hexagonal lattices in the two layers of graphene. For example, by stacking two or more layers of graphene, a band gap is formed in the two-dimensional material layer 1. As a result, the wavelength selection effect of the electromagnetic wave for photoelectric conversion can be obtained. In addition, as the number of layers of the multi-layer graphene constituting the two-dimensional material layer 1 increases, the mobility of the carriers in the channel region decreases. On the other hand, in this case, the two-dimensional material layer 1 is less likely to be affected by the carrier scattering from the base structure of the substrate or the like, and as a result, the noise level decreases. Therefore, with respect to the electromagnetic wave detector using the multi-layer graphene as the two-dimensional material layer 1, the light absorption increases, and the detection sensitivity of the electromagnetic wave can be improved.

[0084] In addition, in a case where the two-dimensional material layer 1 is in contact with the first electrode portion 2a, carriers are doped from the first electrode portion 2a to the two-dimensional material layer 1. For example, in a case where gold (Au) is used as the material of the first electrode portion 2a, holes are doped to the two-dimensional material layer 1 in the vicinity of the first electrode portion 2a due to the difference in work function between the two-dimensional material layer 1 and Au. When the electromagnetic wave detector is driven in an electron conduction state in this state, the mobility of electrons flowing in the channel region of the two-dimensional material layer 1 decreases due to the influence of the holes doped from the first electrode portion 2a to the two-dimensional material layer 1, and the contact resistance between the two-dimensional material layer 1 and the first electrode portion 2a increases. Due to this increase in contact resistance, the mobility of electrons (carriers) in the electromagnetic wave detector caused by the electric field effect decreases, and the performance of the electromagnetic wave detector can decrease. In particular, in a case where single-layer graphene is used as the two-dimensional material layer 1, the amount of doping of carriers injected from the first electrode portion 2a is large. Therefore, the decrease in the mobility of the above-described electrons in the electromagnetic wave detector is particularly significant in a case where single-layer graphene is used as the two-dimensional material layer 1. Therefore, in a case where the two-dimensional material layer 1 is entirely formed of single-layer graphene, there is a possibility that the performance of the electromagnetic wave detector decreases.

[0085] Therefore, the above-described first portion of the two-dimensional material layer 1 to which carriers from the first electrode portion 2a are easily doped can also be composed of multi-layer graphene. Multi-layer graphene is less doped with carriers from the first electrode portion 2a than single-layer graphene. Therefore, it is possible to suppress an increase in contact resistance between the two-dimensional material layer 1 and the first electrode portion 2a. As a result, it is possible to suppress a decrease in the mobility of the above-described electrons in the electromagnetic wave detector, and it is possible to improve the performance of the electromagnetic wave detector.

[0086] In addition, as the two-dimensional material layer 1, graphene nanoribbons (hereinafter also referred to as graphene nanoribbons) can also be used. In this case, as the two-dimensional material layer 1, for example, any structure of a graphene nanoribbon monomer, a complex in which a plurality of graphene nanoribbons are stacked, or a structure in which graphene nanoribbons are periodically arranged on a plane can be used. For example, in a case where a structure in which graphene nanoribbons are periodically arranged is used as the two-dimensional material layer 1, plasmon resonance can occur in the graphene nanoribbons. As a result, it is possible to improve the sensitivity of the electromagnetic wave detector. Here, a structure in which graphene nanoribbons are periodically arranged is sometimes referred to as a graphene metamaterial. Therefore, in an electromagnetic wave detector in which a graphene metamaterial is used as the two-dimensional material layer 1, the above-described effects can also be obtained.

[0087] The ferroelectric layer 5 is disposed on the two-dimensional material layer 1. That is, the ferroelectric layer 5 is disposed on the side opposite to the semiconductor layer 4 with respect to the two-dimensional material layer 1. The ferroelectric layer 5 is in contact with the two-dimensional material layer 1. The ferroelectric layer 5 is disposed on the upper portion of each of the above-mentioned first portion, the above-mentioned second portion, and the above-mentioned third portion of the two-dimensional material layer 1, and is in contact with each of the above-mentioned first portion, the above-mentioned second portion, and the above-mentioned third portion of the two-dimensional material layer 1.

[0088] Specifically, the ferroelectric layer 5 has a fourth portion disposed on the upper portion of the above-mentioned first portion of the two-dimensional material layer 1 and in contact with the above-mentioned first portion, a fifth portion disposed on the upper portion of the above-mentioned second portion of the two-dimensional material layer 1 and in contact with the above-mentioned second portion, and a sixth portion disposed on the upper portion of the above-mentioned third portion of the two-dimensional material layer 1 and in contact with the above-mentioned third portion.

[0089] The thickness of each of the above-mentioned fourth portion, the above-mentioned fifth portion, and the above-mentioned sixth portion of the ferroelectric layer 5 is, for example, equal to each other. On the upper surface of the two-dimensional material layer 1, a concavo-convex is formed due to the above-mentioned first portion, the above-mentioned second portion, and the above-mentioned third portion. The distance between the upper surface of the above-mentioned first portion and the first face of the semiconductor layer 4 is smaller than the distance between the upper surface of the above-mentioned second portion and the first face of the semiconductor layer 4.

[0090] As a material constituting the ferroelectric layer 5, any material can be used as long as it generates polarization with respect to a detection wavelength. The material constituting the ferroelectric layer 5 includes, for example, at least any one of BaTiO3 (barium titanate), LiNbO3 (lithium niobate), LiTaO3 (lithium tantalate), SrTiO3 (strontium titanate), PZT (lead zirconate titanate), SBT (strontium bismuth tantalate), BFO (bismuth ferrite), ZnO (zinc oxide), HfO2 (hafnium oxide), and a polyvinylidene fluoride-based ferroelectric (PVDF, P(VDF-TrFE), P(VDF-TrFE-CTFE), or the like) as an organic polymer. In addition, the ferroelectric layer 5 can be a layer in which different ferroelectric materials are further stacked or mixed.

[0091] Further, the material constituting the ferroelectric layer 5 is not limited to the above-mentioned ferroelectric material, and can be any pyroelectric material that functions as a pyroelectric effect. Specifically, the material constituting the ferroelectric layer 5 can be any ferroelectric material that generates a change in polarization with respect to a change in thermal energy. Under the pyroelectric effect, electromagnetic waves function only as a heat source, and thus there is substantially no wavelength dependence in the pyroelectric effect. Therefore, the ferroelectric layer 5 has sensitivity to electromagnetic waves of a wide frequency band.

[0092] It is preferable that the ferroelectric layer 5 be designed so that the speed of change in dielectric polarization in the ferroelectric layer 5 is as short as possible. Specifically, the thickness of the ferroelectric layer 5 is preferably as thin as possible in a range in which a change in polarization can be provided to the two-dimensional material layer 1.

[0093] Further, the electromagnetic wave detector described above can further have a Mott insulator that is in contact with the ferroelectric layer 5 and that changes in physical properties (for example, temperature) by photoinduced phase transition by light irradiation.

[0094] Further, the ferroelectric layer 5 is configured to overlap at least any one of the above-described first portion, the above-described second portion, and the above-described third portion of the two-dimensional material layer 1, and is configured to change in resistance value of the two-dimensional material layer 1 at the time of change in polarization within the ferroelectric layer 5.

[0095] Further, the film thickness of the ferroelectric layer 5 is preferably a thickness that applies the largest possible electric field to the graphene layer 1 in a case where electromagnetic waves are irradiated to the graphene layer 1. Further, the direction of polarization of the ferroelectric layer 5 is not particularly limited, but is preferably a direction perpendicular to the planar direction of the two-dimensional material layer.

[0096] Further, an unillustrated protective film can be formed on the two-dimensional material layer 1. The protective film can be provided so as to cover the periphery of the two-dimensional material layer 1, the semiconductor layer 4, the first electrode portion 2a, and the ferroelectric layer 5. As a material constituting the protective film, any material can be used, and for example, as the protective film, an insulating film composed of silicon oxide can be used. As a material constituting the protective film, an insulator such as an oxide or a nitride, for example, silicon oxide, silicon nitride, hafnium oxide, aluminum oxide, boron nitride, or the like can be used.

[0097] The electromagnetic wave detector according to the present embodiment has the structure described above.

[0098] <Method for manufacturing electromagnetic wave detector>

[0099] Figure 1 is a flowchart for explaining the method for manufacturing the electromagnetic wave detector according to Embodiment 1. The method for manufacturing the electromagnetic wave detector shown in Figure 2 , the method for manufacturing the electromagnetic wave detector shown in Figure 2 , and the method for manufacturing the electromagnetic wave detector shown in Figure 4 are described with reference to the flowchart.

[0100] First, the preparation step (S1) shown in Figure 5 is performed. In this step (S1), for example, the semiconductor layer 4 composed of silicon or the like is prepared as a flat substrate.

[0101] Next, an electrode forming step (S2) is implemented. In this step (S2), a second electrode portion 2b is formed on the back surface of the semiconductor layer 4. Specifically, a protective film is first formed on the surface of the semiconductor layer 4. As the protective film, for example, a resist is used. In this state, the second electrode portion 2b is formed on the back surface of the semiconductor layer 4. As the material constituting the second electrode portion 2b, for example, a metal such as gold (Au), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), chromium (Cr), or the like can be used. At this time, in order to improve the adhesion of the semiconductor layer 4 and the second electrode portion 2b, an adhesion layer can also be formed on the back surface of the semiconductor layer 4 prior to the second electrode portion 2b. As the material of the adhesion layer, for example, chromium (Cr) or titanium (Ti) can be used. Furthermore, the above step (S2) can also be implemented after the steps (S3 to S7) as long as the surface of the semiconductor layer 4 is protected.

[0102] Next, an insulating film forming step (S3) is implemented. In this step (S3), an insulating film 3 is formed on the surface of the semiconductor layer 4. The insulating film 3, for example, in the case where the semiconductor layer 4 is silicon, can be silicon oxide (SiO2) formed by partially thermally oxidizing the surface of the semiconductor layer 4. Alternatively, the insulating layer can be formed on the surface of the semiconductor layer 4 by a CVD (Chemical vapor deposition) method, a sputtering method, or the like.

[0103] Next, an electrode forming step (S4) is implemented. In this step (S4), a first electrode portion 2a is formed on the insulating film 3. As the material constituting the first electrode portion 2a, for example, a metal such as gold (Au), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), chromium (Cr), or the like is used. At this time, in order to improve the adhesion of the first electrode portion 2a and the insulating film 3, an adhesion layer can also be formed between the insulating film 3 and the first electrode portion 2a. As the material constituting the adhesion layer, for example, chromium (Cr) or titanium (Ti), or the like can be used.

[0104] As the method of forming the first electrode portion 2a, for example, a process such as the following can be used. First, a resist mask is formed on the surface of the insulating film 3 using photolithography or EB drawing, or the like. In the resist mask, an opening portion is formed in the region where the first electrode portion 2a is to be formed. Thereafter, a film of a metal or the like that is to become the first electrode portion 2a is formed on the resist mask. In the formation of this film, a vapor deposition method, a sputtering method, or the like can be used. At this time, the film is formed so as to extend from the inside of the opening portion of the resist mask to the upper surface of the resist mask. Thereafter, by removing the resist mask together with a part of the film, the other part of the film disposed in the opening portion of the resist mask remains on the surface of the insulating film 3, becoming the first electrode portion 2a. The above method is a method generally referred to as lift-off.

[0105] As the method of forming the first electrode portion 2a, another method can be used. For example, a film such as a metal film corresponding to the first electrode portion 2a is first formed on the surface of the insulating film 3. Thereafter, a resist mask is formed on the film by a photolithography method. The resist mask is formed so as to cover the region where the first electrode portion 2a is to be formed, and not to be formed in the region other than the region where the first electrode portion 2a is to be formed. Thereafter, the film is partially removed by wet etching or dry etching using the resist mask as a mask. As a result, a part of the film remains under the resist mask. The part of the film becomes the first electrode portion 2a. Thereafter, the resist mask is removed. In this way, the first electrode portion 2a can be formed.

[0106] Next, an opening portion forming step (S5) is performed. In this step (S5), the opening portion is formed in the insulating film 3. Specifically, a resist mask is formed on the insulating film 3 using photolithography or EB drawing. In the resist mask, the opening portion is formed in the region of the insulating film 3 where the opening portion is to be formed. Thereafter, the insulating film 3 is partially removed by wet etching or dry etching using the resist mask as a mask, and the opening portion is formed. Next, the resist mask is removed. Further, the above step (S5) can be performed prior to the step (S4).

[0107] Next, a two-dimensional material layer forming step (S6) is performed. In this step (S6), the two-dimensional material layer 1 is formed so as to cover the entirety of the first electrode portion 2a, the insulating film 3, and a part of the semiconductor layer 4 exposed in the opening portion of the insulating film 3. As the material constituting the two-dimensional material layer 1, an atomic layer material such as graphene or a molecular layer material can be used. The two-dimensional material layer 1 can be formed by any method. For example, the two-dimensional material layer 1 can be formed by epitaxial growth, or can be transferred and attached to the first electrode portion 2a, the insulating film 3, and a part of the semiconductor layer 4 by transferring the two-dimensional material layer 1 formed in advance by a CVD method. Alternatively, the two-dimensional material layer 1 can be formed by screen printing or the like. Alternatively, the two-dimensional material layer 1 can be transferred onto the above-described first electrode portion 2a or the like by peeling the two-dimensional material layer 1 by mechanical peeling or the like. Next, a resist mask is formed on the two-dimensional material layer 1 using photolithography or the like. The resist mask is formed so as to cover the region where the two-dimensional material layer 1 remains, and not to be formed in the region where the two-dimensional material layer 1 does not remain. Thereafter, the two-dimensional material layer 1 is partially removed by etching using oxygen plasma with the resist mask serving as a mask. Thus, the part of the two-dimensional material layer 1 that is not needed is removed, and the two-dimensional material layer 1 as shown in FIGS. 1 and 2 is formed. Thereafter, the resist mask is removed. Figure 4 and Figure 6

[0108] ​Next, the ferroelectric layer formation process (S7) is performed. In this process (S7), a ferroelectric layer 5 is formed on the two-dimensional material layer 1. Materials used to form the ferroelectric layer 5 include, for example, BaTiO3 (barium titanate), LiNbO3 (lithium niobate), LiTaO3 (lithium tantalate), SrTiO3 (strontium titanate), PZT (lead zirconate titanate), SBT (strontium bismuth tantalate), BFO (bismuth ferrite), ZnO (zinc oxide), HfO2 (hafnium oxide), and polyvinylidene fluoride-based ferroelectric materials as organic polymers. Furthermore, the ferroelectric layer 5 can be formed by any method. For example, if the ferroelectric layer 5 is composed of a polymer-based material, it can be processed using photolithography after forming a polymer film by spin coating or similar methods. With other materials, it can be patterned using photolithography after forming a film by sputtering, vapor deposition, MOD coating, or similar methods. Alternatively, a method known as stripping can be used, in which the resist mask is removed after the ferroelectric material has been coated using the resist mask as a mask.

[0109] Through the above processes (S1~S7), we can obtain Figure 7 as well as Figure 5 to Figure 7 The electromagnetic wave detector shown is an example. Furthermore, while the two-dimensional material layer 1 is formed on the first electrode portion 2a using the above manufacturing method, the two-dimensional material layer 1 can also be pre-formed on the insulating film 3, and the first electrode portion 2a can be formed by overlapping a portion of this two-dimensional material layer 1. However, when using this configuration, care must be taken to avoid damaging the two-dimensional material layer 1 during the formation of the first electrode portion 2a. For example, one could consider forming the first electrode portion 2a while pre-covering the area of ​​the two-dimensional material layer 1 where the first electrode portion 2a is formed with a protective film or similar material.

[0110] Operating principle of electromagnetic wave detectors

[0111] Next, the operating principle of the electromagnetic wave detector involved in this embodiment will be explained.

[0112] First, such as Figure 4 As shown, a power supply circuit for applying voltage V is electrically connected between the first electrode portion 2a and the second electrode portion 2b, connecting the first electrode portion 2a, the two-dimensional material layer 1, the semiconductor layer 4, and the second electrode portion 2b in the described order. Next, a voltage V is applied between the first electrode portion 2a and the second electrode portion 2b. Preferably, the voltage V is set to be reverse biased relative to the Schottky junction of the two-dimensional material layer 1 and the semiconductor layer 4. By applying voltage V, a current I flows through the two-dimensional material layer 1, which becomes part of the current path between the first electrode portion 2a and the second electrode portion 2b. A galvanometer (not shown) is provided in the power supply circuit to monitor the current I flowing through the two-dimensional material layer 1.

[0113] Next, the ferroelectric layer 5 is irradiated with electromagnetic waves. In this case, a change in dielectric polarization occurs in the inside of the ferroelectric layer 5 by the pyroelectric effect of the ferroelectric layer 5. Due to this, a change in polarization in the ferroelectric layer 5 provides a change in electric field to the two-dimensional material layer 1. As a result, it becomes a state in which a gate voltage is virtually applied to the two-dimensional material layer 1, and the resistance value in the two-dimensional material layer 1 changes. This is called a photo-gate effect. By the change in the resistance value in the two-dimensional material layer 1, the current I as a photo current flowing in the two-dimensional material layer 1 changes. By detecting the change in this current I, it is possible to detect electromagnetic waves irradiated to the electromagnetic wave detector.

[0114] In addition, for example, in a case where the semiconductor layer 4 constituting the semiconductor layer 4 is composed of p-type material silicon and the two-dimensional material layer 1 is composed of n-type material graphene, the two-dimensional material layer 1 and the semiconductor layer 4 are Schottky-joined. At this time, the voltage V is adjusted, a reverse bias is applied to the above-described Schottky junction, and thus it is possible to make the current I zero. That is, in the electromagnetic wave detector according to the present embodiment, it is possible to perform a disconnection operation.

[0115] In addition, at the time of irradiation of the ferroelectric layer 5 with electromagnetic waves, by the pyroelectric effect, the dielectric polarization of the ferroelectric layer 5 changes, the Fermi level of the two-dimensional material layer 1 is modulated, and the energy barrier of the two-dimensional material layer 1 and the semiconductor layer 4 is lowered. As a result, only at the time when electromagnetic waves are irradiated, a current flows in the semiconductor layer 4, and the current I is detected.

[0116] Here, the electromagnetic wave detector according to the present embodiment is not limited to the structure described above that detects a change in current in the two-dimensional material layer 1, and for example, a constant current can flow between the first electrode portion 2a and the second electrode portion 2b, and a change in voltage V (that is, a change in voltage value in the two-dimensional material layer 1) between the first electrode portion 2a and the second electrode portion 2b can be detected.

[0117] In addition, the same electromagnetic wave detector can be used two or more to detect electromagnetic waves. For example, two or more of the same electromagnetic wave detector is prepared. One electromagnetic wave detector is disposed in a shielded space that is not irradiated with electromagnetic waves. The other electromagnetic wave detector is disposed in a space irradiated with electromagnetic waves as a measurement target. Furthermore, a difference between the current I or the voltage V of the other electromagnetic wave detector irradiated with electromagnetic waves and the current I or the voltage V of the electromagnetic wave detector disposed in the shielded space is detected. In this way, it is also possible to detect electromagnetic waves.

[0118] <Operation of electromagnetic wave detector>

[0119] Next, the operation of the electromagnetic wave detector according to the present embodiment will be described. Figure 4 and Figure 1The specific operation of the electromagnetic wave detector is shown. Here, a case where p-type silicon is used as the semiconductor layer 4, graphene is used as the two-dimensional material layer 1, and lithium niobate is used as the ferroelectric layer 5 is described.

[0120] As shown in Figure 2 When a voltage is applied in a manner that the Schottky junction with the two-dimensional material layer 1 and the semiconductor layer 4 is reverse-biased, a depletion layer is formed in the vicinity of the junction interface of the two-dimensional material layer 1 and the semiconductor layer 4. The range of the detection wavelength of the electromagnetic wave detector is determined in accordance with the absorption wavelength of lithium niobate.

[0121] When an electromagnetic wave of the detection wavelength is incident on the ferroelectric layer 5, a change in dielectric polarization occurs in the ferroelectric layer 5 by the pyroelectric effect. By the change in polarization in the ferroelectric layer 5, a change in electric field is generated in the two-dimensional material layer 1. This is the above-described light gate effect. As described above, the graphene constituting the two-dimensional material layer 1 has a high mobility, and a large displacement current can be obtained in response to a slight change in electric field. Therefore, by the pyroelectric effect of the ferroelectric layer 5, the Fermi level of the two-dimensional material layer 1 is greatly changed, and the energy barrier with the semiconductor layer 4 is lowered. As a result, charge is injected from the first electrode portion 2a into the two-dimensional material layer 1. Furthermore, the photo-injected current charge taken out from the semiconductor layer 4 is greatly amplified in the two-dimensional material layer 1 by the light gate effect. Therefore, in the electromagnetic wave detector according to the present embodiment, high sensitivity exceeding the quantum efficiency of 100% can be achieved.

[0122] Furthermore, if the speed of the change in dielectric polarization of the ferroelectric layer 5 is designed to be as short as possible, the time from the incidence of the electromagnetic wave on the electromagnetic wave detector to the generation of the change in resistance value in the two-dimensional material layer 1 becomes short. According to such an electromagnetic wave detector, the delay of amplification due to the light gate effect is eliminated, and high-speed responsiveness can be achieved.

[0123] <Effects>

[0124] The electromagnetic wave detector according to the present embodiment includes: a semiconductor layer 4; a two-dimensional material layer 1 electrically connected to the semiconductor layer 4; a first electrode portion 2a electrically connected to the two-dimensional material layer 1 without passing through the semiconductor layer 4; a second electrode portion 2b electrically connected to the two-dimensional material layer 1 via the semiconductor layer 4; and a ferroelectric layer 5 in contact with at least a part of the two-dimensional material layer 1.

[0125] In the above-described electromagnetic wave detector, when the polarization in the ferroelectric layer 5 changes by the pyroelectric effect, the resistance value of the two-dimensional material layer 1 can change. As a result, the conductivity of the two-dimensional material layer 1 is modulated by the above-described light gate effect, and as a result, the photoelectric current can be amplified in the two-dimensional material layer 1.

[0126] The amount of change in current in the two-dimensional material layer 1 caused by a change in polarization in the ferroelectric layer 5 is larger than that in a general semiconductor. In particular, in the two-dimensional material layer 1, a large change in current occurs in response to a slight change in electric potential, as compared with a general semiconductor. For example, in the case where a single layer of graphene is used as the two-dimensional material layer 1, the thickness of the two-dimensional material layer 1 is one atomic layer, and is extremely thin. In addition, the mobility of electrons in a single layer of graphene is large. In this case, the above-mentioned amount of change in current in the two-dimensional material layer 1 calculated from the mobility and the thickness of the two-dimensional material layer 1 and the like becomes several hundred to several thousand times larger than that in a general semiconductor.

[0127] Therefore, by utilizing the photogate effect, the extraction efficiency of the detection current in the two-dimensional material layer 1 is greatly improved. Such a photogate effect does not directly enhance the quantum efficiency of a photoelectric conversion material as in a general semiconductor, but increases the change in current due to the incidence of electromagnetic waves. Therefore, the quantum efficiency of the above-mentioned electromagnetic wave detector calculated from the differential current due to the incidence of electromagnetic waves can exceed 100%. Therefore, the detection sensitivity of the electromagnetic wave detector according to the present embodiment in detecting electromagnetic waves is higher than that of a conventional semiconductor electromagnetic wave detector or a graphene electromagnetic wave detector that does not utilize the photogate effect.

[0128] In addition, the electromagnetic wave detector according to the present embodiment further includes an insulating film 3 in which an opening portion is formed that is in contact with a part of the semiconductor layer 4 and opens another part of the semiconductor layer 4. The two-dimensional material layer 1 is electrically connected to the above-mentioned another part of the semiconductor layer 4 at the above-mentioned opening portion, and specifically, is Schottky-junctioned to the semiconductor layer 4. By the Schottky junction of the two-dimensional material layer 1 and the semiconductor layer 4, no current flows when a reverse bias is applied, and the electromagnetic wave detector can perform a breaking operation.

[0129] In addition, in the electromagnetic wave detector according to the present embodiment, the above-mentioned two-dimensional material layer 1 has a region disposed on the insulating film 3, and thus is more easily modulated in conductivity by the above-mentioned photogate effect than when the two-dimensional material layer 1 does not have a region disposed on the insulating film 3.

[0130] In addition, in the electromagnetic wave detector according to the present embodiment, the amount of change in the current value I when the electromagnetic wave detector is irradiated with the electromagnetic wave includes, in addition to the amount of change in the current due to the change in the resistance of the two-dimensional material layer 1 caused by the dielectric polarization occurring in the ferroelectric layer 5 and the amount of change in the current due to the energy barrier change of the two-dimensional material layer 1 and the semiconductor layer 4, the amount of change in the current due to the photoelectric conversion occurring in the two-dimensional material layer 1. That is, in the electromagnetic wave detector according to the present embodiment, by the incidence of the electromagnetic wave, in addition to the current generated in the above-mentioned photo gate effect and the current accompanying the energy barrier change, the photocurrent caused by the photoelectric conversion efficiency of the two-dimensional material layer 1 itself can be detected.

[0131] As described above, the electromagnetic wave detector according to the present embodiment can simultaneously achieve high sensitivity with a quantum efficiency of 100% or more and a break operation.

[0132] In addition, in the electromagnetic wave detector according to the present embodiment, when silicon is used in the semiconductor layer 4, a readout circuit can be formed in the semiconductor layer 4. Thus, the signal can be read out without forming a circuit outside the element.

[0133] Embodiment 2

[0134] Structure of electromagnetic wave detector

[0135] Figure 1 is a schematic plan view of the electromagnetic wave detector according to Embodiment 2. Figure 2 is a schematic cross-sectional view along the line segment V-V of Figure 4 . Figure 5 is a schematic cross-sectional view illustrating a first modification of the electromagnetic wave detector according to Embodiment 2. Figure 6 is a schematic cross-sectional view illustrating a second modification of the electromagnetic wave detector according to Embodiment 2. In addition, Figure 5 correspond to Figure 5 .

[0136] Figure 6 The electromagnetic wave detector illustrated in Figure 7 has basically the same structure as the electromagnetic wave detectors illustrated in Figure 5 , and the same effects can be obtained, but the configuration of the ferroelectric layer 5 is different from that of the electromagnetic wave detectors illustrated in Figure 5 and Figure 7 . That is, in the electromagnetic wave detector illustrated in Figure 8 , the ferroelectric layer 5 is disposed at the lower portion of the two-dimensional material layer 1 or the insulating film 3. In Figure 9 , the ferroelectric layer 5 is formed at the lower portion of the two-dimensional material layer 1 and the upper portion of the semiconductor layer 4.

[0137] Figure 8The first modification of the electromagnetic wave detector according to Embodiment 2 basically has the same structure as the electromagnetic wave detector according to Embodiment 2, but the configuration of the ferroelectric layer 5 is different from that of the electromagnetic wave detector according to Embodiment 2. That is, in the electromagnetic wave detector according to Embodiment 2, the ferroelectric layer 5 is formed on the lower portion of the two-dimensional material layer 1 and the upper portion of the semiconductor layer 4. Figure 8 The electromagnetic wave detector according to Embodiment 2 basically has the same structure as the electromagnetic wave detector according to Embodiment 2, but the configuration of the ferroelectric layer 5 is different from that of the electromagnetic wave detector according to Embodiment 2. That is, in the electromagnetic wave detector according to Embodiment 2, the ferroelectric layer 5 is formed on the lower portion of the two-dimensional material layer 1 and the upper portion of the semiconductor layer 4. Figure 1 The electromagnetic wave detector according to Embodiment 2 basically has the same structure as the electromagnetic wave detector according to Embodiment 2, but the configuration of the ferroelectric layer 5 is different from that of the electromagnetic wave detector according to Embodiment 2. That is, in the electromagnetic wave detector according to Embodiment 2, the ferroelectric layer 5 is formed on the lower portion of the two-dimensional material layer 1 and the upper portion of the semiconductor layer 4. Figure 2 The electromagnetic wave detector according to Embodiment 2 basically has the same structure as the electromagnetic wave detector according to Embodiment 2, but the configuration of the ferroelectric layer 5 is different from that of the electromagnetic wave detector according to Embodiment 2. That is, in the electromagnetic wave detector according to Embodiment 2, the ferroelectric layer 5 is formed on the lower portion of the two-dimensional material layer 1 and the upper portion of the semiconductor layer 4.

[0138] Figure 1 The second modification of the electromagnetic wave detector according to Embodiment 2 basically has the same structure as the electromagnetic wave detector according to Embodiment 2, but the configuration of the ferroelectric layer 5 is different from that of the electromagnetic wave detector according to Embodiment 2. That is, in the electromagnetic wave detector according to Embodiment 2, the ferroelectric layer 5 is formed on the lower portion of the two-dimensional material layer 1 and the upper portion of the semiconductor layer 4. Figure 2 The electromagnetic wave detector according to Embodiment 2 basically has the same structure as the electromagnetic wave detector according to Embodiment 2, but the configuration of the ferroelectric layer 5 is different from that of the electromagnetic wave detector according to Embodiment 2. That is, in the electromagnetic wave detector according to Embodiment 2, the ferroelectric layer 5 is formed on the lower portion of the two-dimensional material layer 1 and the upper portion of the semiconductor layer 4. Figure 10 The electromagnetic wave detector according to Embodiment 2 basically has the same structure as the electromagnetic wave detector according to Embodiment 2, but the configuration of the ferroelectric layer 5 is different from that of the electromagnetic wave detector according to Embodiment 2. That is, in the electromagnetic wave detector according to Embodiment 2, the ferroelectric layer 5 is formed on the lower portion of the two-dimensional material layer 1 and the upper portion of the semiconductor layer 4. Figure 11 The electromagnetic wave detector according to Embodiment 2 basically has the same structure as the electromagnetic wave detector according to Embodiment 2, but the configuration of the ferroelectric layer 5 is different from that of the electromagnetic wave detector according to Embodiment 2. That is, in the electromagnetic wave detector according to Embodiment 2, the ferroelectric layer 5 is formed on the lower portion of the two-dimensional material layer 1 and the upper portion of the semiconductor layer 4.

[0139] <Effects>

[0140] In the electromagnetic wave detector according to Embodiment 2, the ferroelectric layer 5 is disposed on the lower portion of the two-dimensional material layer 1 or the lower portion of the insulating film 3.

[0141] In this case, the ferroelectric layer 5 is disposed on the lower portion of the two-dimensional material layer 1 or the lower portion of the insulating film 3, so that the two-dimensional material layer 1 can eliminate process damage in the film formation of the ferroelectric layer 5 and can prevent the performance of the two-dimensional material layer 1 from being degraded, and thus the electromagnetic wave detector can be made highly sensitive.

[0142] In this case, the ferroelectric layer 5 is disposed on the lower portion of the two-dimensional material layer 1 or the lower portion of the insulating film 3, so that the two-dimensional material layer 1 can eliminate process damage in the film formation of the ferroelectric layer 5 and can prevent the performance of the two-dimensional material layer 1 from being degraded, and thus the electromagnetic wave detector can be made highly sensitive.

[0143] Embodiment 3

[0144] <Structure of electromagnetic wave detector>

[0145] Figure 10 is a schematic top view of the electromagnetic wave detector according to Embodiment 3. Figure 12 is a schematic cross-sectional view taken along line A-A' in Figure 13A cross-sectional view of line segment IX-IX.

[0146] Figure 12 The electromagnetic wave detector shown basically has the same characteristics as... Figure 14 as well as Figure 15 The electromagnetic wave detector shown has the same structure and can achieve the same effect, but in terms of the two-dimensional material layer 1, the first electrode portion 2a, the second electrode portion 2b, and the semiconductor layer 4 being disposed on the ferroelectric layer 5, it is similar to... Figure 14 as well as Figure 10 The electromagnetic wave detector shown is different. That is, it is characterized by having a semiconductor layer 4 and a first electrode portion 2a disposed on a portion of the ferroelectric layer 5, a second electrode portion 2b disposed on the semiconductor layer 4, and a two-dimensional material layer 1 extending from the first electrode portion 2a through the ferroelectric layer 5 to the semiconductor layer 4.

[0147] <Effects>

[0148] The aforementioned electromagnetic wave detector has layers formed on the ferroelectric layer 5. Therefore, the ferroelectric layer 5 can be configured as a ferroelectric crystalline substrate. This ferroelectric layer 5 has higher crystallinity and is thicker than a ferroelectric layer 5 that is not configured as a ferroelectric crystalline substrate. The rate of polarization change generated by electromagnetic wave irradiation in this ferroelectric layer 5 is higher than that in a ferroelectric layer 5 that is not configured as a ferroelectric crystalline substrate, thus improving the sensitivity of the electromagnetic wave detector. Furthermore, in the electromagnetic wave detector according to Embodiment 1, when the ferroelectric layer 5 is deposited on the two-dimensional material layer 1, the two-dimensional material layer 1 may be damaged by the process. In contrast, in the electromagnetic wave detector according to Embodiment 3, the two-dimensional material layer 1 is not subject to the aforementioned process damage, thus preventing performance degradation of the two-dimensional material layer 1 and enabling high sensitivity of the electromagnetic wave detector.

[0149] Here, the structure of the electromagnetic wave detector involved in this embodiment can also be applied to other embodiments.

[0150] Implementation method 4.

[0151] <Structure of an Electromagnetic Wave Detector>

[0152] Figure 1 This is a top view schematic diagram of the electromagnetic wave detector involved in Embodiment 4. Figure 2 It is along Figure 1 A cross-sectional diagram of line segment XI-XI. Figure 2 This is a top view schematic diagram showing a first modified example of the electromagnetic wave detector according to Embodiment 4. Figure 10 It is along Figure 12 A cross-sectional schematic diagram of line segment XIII-XIII. Figure 14 This is a top view schematic diagram showing a second variation of the electromagnetic wave detector according to Embodiment 4.Figure 16 is a cross-sectional view taken along the line segment XV-XV of Figure 16 .

[0153] Figure 1 The electromagnetic wave detector shown in FIG. 6 has substantially the same structure as the electromagnetic wave detectors shown in FIGS. 1 to 5 and FIG. 7, and can achieve the same effects, but the ferroelectric layer 5 is disposed differently from the electromagnetic wave detectors shown in FIGS. 1 to 5 and FIG. 7. That is, in the electromagnetic wave detector shown in FIG. 6, the ferroelectric layer 5 is disposed only on the upper portion of the interface between the two-dimensional material layer 1 and the semiconductor layer 4. In other words, the ferroelectric layer 5 is disposed so as to overlap only the above-mentioned first portion of the two-dimensional material layer 1 and to be in contact with only the above-mentioned first portion. Figure 17 Figure 18 Figure 17 Figure 16 Figure 1

[0154] In the first modification of the electromagnetic wave detector according to Embodiment 4, the ferroelectric layer 5 is disposed only on the upper portion of the two-dimensional material layer 1 on the insulating film 3. In other words, the ferroelectric layer 5 is disposed so as to overlap only the above-mentioned second portion and the above-mentioned third portion of the two-dimensional material layer 1 and to be in contact with only the above-mentioned second portion and the above-mentioned third portion. Figure 2

[0155] In the second modification of the electromagnetic wave detector according to Embodiment 4, the ferroelectric layer 5 is disposed on a portion of the two-dimensional material layer 1. In other words, the ferroelectric layer 5 is disposed so as to overlap only the above-mentioned third portion of the two-dimensional material layer 1 and to be in contact with only the above-mentioned third portion. Figure 1 <Effects>

[0156]

[0157] In the above-described electromagnetic wave detector, the ferroelectric layer 5 is disposed on the upper portion of the interface between the two-dimensional material layer 1 and the semiconductor layer 4. In this case, when an electromagnetic wave is incident on the ferroelectric layer 5, the energy barrier of the two-dimensional material layer 1 and the semiconductor layer 4 can be changed by the polarization change of the ferroelectric layer 5, and the electromagnetic wave detector can be made highly sensitive.

[0158] In the first modification of the above-described electromagnetic wave detector, the ferroelectric layer 5 is disposed only on the upper portion of the two-dimensional material layer 1 on the insulating film 3. In this case, when an electromagnetic wave is incident on the ferroelectric layer 5, the conductivity of the two-dimensional material layer 1 can be modulated by the polarization change of the ferroelectric layer 5, and the electromagnetic wave detector can be made highly sensitive.

[0159] ​​​​​​​In addition, in the second modification of the electromagnetic wave detector described above, the ferroelectric layer 5 is arranged on a part of the two-dimensional material layer 1. In this case, when an electromagnetic wave is incident on the ferroelectric layer 5, a modulation of the electrical conductivity is generated in the vicinity of the region where the ferroelectric layer 5 is in contact. Thus, the modulation of the electrical conductivity can be performed on an arbitrary region of the two-dimensional material layer 1.

[0160] Here, the structure of the electromagnetic wave detector according to the present embodiment can also be applied to other embodiments.

[0161] Embodiment 5

[0162] <Structure of electromagnetic wave detector>

[0163] Figure 2 is a cross-sectional view of the electromagnetic wave detector according to Embodiment 5. Figure 17 corresponds to. Figure 18 Figure 8 is a top view schematically showing a first modification of the electromagnetic wave detector according to Embodiment 5. Figure 9 is a cross-sectional view along the line segment XVIII-XVIII of Figure 8

[0164] Figure 9 The electromagnetic wave detector shown in FIG. 18 basically has the same structure as the electromagnetic wave detectors shown in FIGS. 1 and 2, and the same effects can be obtained, but differs from the electromagnetic wave detectors shown in FIGS. 1 and 2 in that the insulating film 3b that separates the ferroelectric layer 5 from the two-dimensional material layer 1 is provided. In other words, the electromagnetic wave detector shown in FIG. 18 basically has the same structure as the electromagnetic wave detector shown in FIG. 3, and the same effects can be obtained, but differs from the electromagnetic wave detector shown in FIG. 3 in that the two-dimensional material layer 1, the first electrode portion 2a, the second electrode portion 2b, the semiconductor layer 4, and the insulating film 3b are arranged on the ferroelectric layer 5. Figure 17 Figure 18 Figure 16 Figure 16

[0165] Figure 1 Figure 2 Figure 19 Figure 19 Figure 1 Figure 19 Figure 1 Figure 2 Figure 1 Figure 2

[0166] ​​​​​​​​​​​​​​​​The thickness of the insulating film 3b is preferably the thickness that can provide the electric field change generated by the pyroelectric effect of the ferroelectric layer 5 to the two-dimensional material layer 1 without shielding the electric field change.

[0167] <Effects>

[0168] In the electromagnetic wave detector described above, the insulating film 3b is disposed between the ferroelectric layer 5 and the two-dimensional material layer 1.

[0169] By interposing the insulating film 3b between the ferroelectric layer 5 and the two-dimensional material layer 1, the ferroelectric layer 5 does not directly contact the two-dimensional material layer 1. In the case where the ferroelectric layer 5 directly contacts the two-dimensional material layer 1, the spontaneous polarization of the ferroelectric layer 5 and the exchange of electric charges between the two-dimensional material layer 1 are generated, so the light response becomes small. In addition, in the case where the ferroelectric layer 5 and the two-dimensional material layer 1 contact each other, there is a possibility that hysteresis is generated and the response speed of the electromagnetic wave detector is reduced. By interposing the insulating film 3b, these effects can be suppressed. In addition, even in the case where the insulating film 3b is interposed, the electric field change generated by the pyroelectric effect of the ferroelectric layer 5 can be provided to the two-dimensional material layer 1.

[0170] In addition, in the case where the insulating film 3b absorbs the electromagnetic wave of the detection wavelength and generates heat, by providing heat energy to the ferroelectric layer 5 by using the heat generation of the insulating film 3b, the polarization change can be increased, and the electromagnetic wave detector can be made highly sensitive.

[0171] Here, the structure of the electromagnetic wave detector according to the present embodiment can also be applied to other embodiments.

[0172] Embodiment 6.

[0173] <Structure of electromagnetic wave detector>

[0174] In the electromagnetic wave detector according to the present embodiment, the position of the end portion of the two-dimensional material layer 1 in plan view is not particularly limited, but in the electromagnetic wave detector according to the present embodiment, the above-described first portion of the two-dimensional material layer 1 has the end portion of the two-dimensional material layer 1 in plan view. The electromagnetic wave detector according to the present embodiment basically has the same structure as the electromagnetic wave detector shown in Figure 19 and Figure 20 the same effects can be obtained, but the end portion of the two-dimensional material layer 1 is disposed on the semiconductor layer 4.

[0175] In other words, the end portion of the two-dimensional material layer 1 in plan view is disposed in the opening portion of the insulating film 3. The above-described end portion of the two-dimensional material layer 1 is, for example, an end portion in the length direction of the two-dimensional material layer 1.

[0176] The shape of the end of the two-dimensional material layer 1 when viewed from above is, for example, rectangular, but it can also be triangular or comb-shaped. Furthermore, the first portion of the two-dimensional material layer 1 may have multiple ends electrically connected to the semiconductor layer 4. Alternatively, the first portion of the two-dimensional material layer 1 may only have a portion of the end of the two-dimensional material layer 1 when viewed from above. For example, the end of the two-dimensional material layer 1 when viewed from above may have a portion disposed within an opening in the insulating film 3 and a portion disposed on the insulating film 3.

[0177] Alternatively, the aforementioned end of the two-dimensional material layer 1 can also be a graphene nanoribbon. In this case, the graphene nanoribbon has a band gap, so a Schottky junction is formed at the junction region between the graphene nanoribbon and the semiconductor portion, thereby reducing dark current and improving the sensitivity of the electromagnetic wave detector.

[0178] <Effects>

[0179] In the aforementioned electromagnetic wave detector, the end of the two-dimensional material layer 1 is located on the semiconductor layer 4. In this case, the junction region between the two-dimensional material layer 1 and the semiconductor portion forms a Schottky junction. As a result, by operating the two-dimensional material layer 1 and the semiconductor portion with reverse bias, the dark current of the electromagnetic wave detector can be reduced, and the sensitivity can be improved. Furthermore, by operating the two-dimensional material layer 1 and the semiconductor portion with forward bias, the extracted photocurrent can be amplified, thereby improving the sensitivity.

[0180] The structure of the electromagnetic wave detector described in this embodiment can also be applied to other embodiments.

[0181] Implementation method 7.

[0182] <Structure of an Electromagnetic Wave Detector>

[0183] Figure 20 This is a cross-sectional schematic diagram of the electromagnetic wave detector involved in Embodiment 7. Figure 1 and Figure 20 correspond.

[0184] Figure 1 The electromagnetic wave detector shown basically has the same characteristics as... Figure 2 as well as Figure 1 The electromagnetic wave detector shown has the same structure and can achieve the same effect, but the structure of the connection between the semiconductor layer 4 and the two-dimensional material layer 1 is different. Figure 2 as well as Figure 20 The electromagnetic wave detectors shown are different. That is, Figure 20 The electromagnetic wave detector shown also has a tunnel insulating layer 6 disposed between the two-dimensional material layer 1 and the semiconductor layer 4.

[0185] The tunnel insulating layer 6 is provided inside the opening portion of the insulating film 3. The thickness of the tunnel insulating layer 6 is set to generate a tunnel current between the two-dimensional material layer 1 and the semiconductor layer 4 when an electromagnetic wave that is a detection target is incident on the two-dimensional material layer 1 and the ferroelectric layer 5. The thickness of the tunnel insulating layer 6 is, for example, 1 nm or more and 10 nm or less. The material constituting the tunnel insulating layer 6 is an arbitrary material having electrical insulation, and, for example, includes at least one selected from the group consisting of a metal oxide such as aluminum oxide and hafnium oxide, or an oxide of a semiconductor including silicon oxide and silicon nitride, and a nitride such as boron nitride. As a method of producing the tunnel insulating layer 6, an arbitrary method can be used. For example, the tunnel insulating layer 6 can be produced using an ALD (Atomic Layer Deposition) method, a vacuum evaporation method, a sputtering method, or the like. Alternatively, the tunnel insulating layer 6 can be formed by oxidizing or nitriding the surface of the semiconductor layer 4. Alternatively, a natural oxide film formed on the surface of the semiconductor layer 4 can be used as the tunnel insulating layer 6.

[0186] Here, the structure of the electromagnetic wave detector according to the present embodiment can also be applied to other embodiments.

[0187] <Effects>

[0188] The above-described electromagnetic wave detector has the tunnel insulating layer 6. The tunnel insulating layer 6 is provided between the two-dimensional material layer 1 and the semiconductor layer 4. The tunnel insulating layer 6 has a thickness that enables a tunnel current to be formed between the two-dimensional material layer 1 and the semiconductor layer 4. In this case, by making the film thickness of the tunnel insulating layer 6 a thickness that enables tunnel injection from the semiconductor layer 4 to the two-dimensional material layer 1, the injection efficiency is improved, and thus a large photocurrent is injected to the two-dimensional material layer 1, and the sensitivity of the electromagnetic wave detector can be improved. In addition, by suppressing the leakage current in the junction interface of the semiconductor layer 4 and the two-dimensional material layer 1 using the tunnel insulating layer 6, the dark current can be reduced.

[0189] Embodiment 8.

[0190] <Structure of electromagnetic wave detector>

[0191] Figure 21 is a cross-sectional view schematically showing an electromagnetic wave detector according to Embodiment 8. Furthermore, Figure 21 corresponds to Figure 1

[0192] Figure 21 The electromagnetic wave detector shown in Figure 1 and Figure 2 has basically the same structure as the electromagnetic wave detector shown in Figure 21 and Figure 22 ​The electromagnetic wave detectors shown are different. That is, Figure 23 The electromagnetic wave detector shown also includes a third electrode portion 2c that is in contact with the ferroelectric layer 5 and disposed on the side opposite to the two-dimensional material layer 1. The third electrode portion 2c is disposed on the upper part of the ferroelectric layer 5. The third electrode portion 2c is electrically connected to the surface of the ferroelectric layer 5, and a voltage V is applied between the third electrode portion 2c and the first electrode portion 2a or the second electrode portion 2b.

[0193] When an electromagnetic wave is incident on the ferroelectric layer 5 from the third electrode portion 2c side, the third electrode portion 2c preferably exhibits high transmittance at the wavelength of the electromagnetic wave detected by the electromagnetic wave detector.

[0194] Here, the third electrode portion 2c is positioned on the side opposite to the two-dimensional material layer 1, but it only needs to contact the ferroelectric layer 5; other structures are also possible. Furthermore, the direction in which the voltage is applied from the third electrode portion 2c is preferably perpendicular to the extending direction of the two-dimensional material layer 1. The structure of the electromagnetic wave detector according to this embodiment can also be applied to other embodiments.

[0195] <Effects>

[0196] The aforementioned electromagnetic wave detector includes a third electrode portion 2c. The third electrode portion 2c is electrically connected to the ferroelectric layer 5. In this case, a voltage can be applied to the third electrode portion 2c, and the polarization of the ferroelectric layer 5 can be controlled. Figure 22 The same voltage as that applied to the first electrode 2a can be applied, but other voltages can also be applied. By controlling the polarization of the ferroelectric layer 5, the polarization change irradiated by electromagnetic waves can be controlled, and the energy barrier of the two-dimensional material layer 1 and the semiconductor layer 4 can be efficiently reduced by electromagnetic wave irradiation, thus improving the sensitivity of the electromagnetic wave detector.

[0197] Implementation method 9.

[0198] <Structure of an Electromagnetic Wave Detector>

[0199] Figure 24 This is a cross-sectional schematic diagram of the electromagnetic wave detector according to Embodiment 9. Furthermore, Figure 22 and Figure 25 correspond.

[0200] Figure 26 The electromagnetic wave detector shown basically has the same characteristics as... Figure 25 as well as Figure 27 The electromagnetic wave detector shown has the same structure and can achieve the same effect, but the structure of the connection between the two-dimensional material layer 1 and the semiconductor layer 4 is different. Figure 28 as well as Figure 27 The electromagnetic wave detectors shown are different. That is, Figure 22The electromagnetic wave detector shown also includes a connecting conductor portion 2d that electrically connects the two-dimensional material layer 1 and the semiconductor layer 4.

[0201] The conductive portion 2d is disposed inside the opening of the insulating film 3. Viewed from above, the conductive portion 2d is configured to overlap and contact both the two-dimensional material layer 1 and the semiconductor layer 4. The lower surface of the conductive portion 2d contacts the upper surface of the semiconductor layer 4. The upper surface of the conductive portion 2d contacts the lower surface of the two-dimensional material layer 1. Preferably, the position of the upper surface of the conductive portion 2d is substantially the same as the position of the upper surface of the insulating film 3. In other words, preferably, the thickness of the conductive portion 2d is equal to the thickness of the insulating film 3. In this case, the two-dimensional material layer 1 extends planarly from the upper surface of the insulating film 3 to the upper surface of the conductive portion 2d without bending.

[0202] When an electromagnetic wave is incident on the ferroelectric layer 5 from the side of the connecting conductor portion 2d, the connecting conductor portion 2d preferably exhibits high transmittance at the wavelength of the electromagnetic wave detected by the electromagnetic wave detector.

[0203] The structure of the electromagnetic wave detector described in this embodiment can also be applied to other embodiments.

[0204] <Effects>

[0205] The aforementioned electromagnetic wave detector includes a conductive connection portion 2d. The conductive connection portion 2d electrically connects the semiconductor layer 4 and the two-dimensional material layer 1. In this case, by providing the conductive connection portion 2d between the two-dimensional material layer 1 and the semiconductor layer 4, the contact resistance between the two-dimensional material layer 1 and the semiconductor layer 4 can be reduced. Furthermore, the conductive connection portion 2d and the semiconductor layer 4 form a Schottky junction, which can reduce dark current.

[0206] Furthermore, it is preferable that the thickness of the conductive portion 2d and the thickness of the insulating film 3 are substantially the same, and that the position of the upper surface of the conductive portion 2d is substantially the same as the position of the upper surface of the insulating film 3. In this case, the two-dimensional material layer 1 is formed horizontally without bending, so the mobility of charge carriers in the two-dimensional material layer 1 is increased. The photoblock effect is proportional to the mobility, so the sensitivity of the electromagnetic wave detector is improved.

[0207] Implementation method 10.

[0208] <Structure of an Electromagnetic Wave Detector>

[0209] Figure 1 This is a top view schematic diagram of the electromagnetic wave detector involved in Embodiment 10. Figure 2 It is along Figure 1 A cross-sectional schematic diagram of line segment XXIII-XXIII.Figure 2 It is along Figure 22 A cross-sectional diagram of line segment XXIV-XXIV. Figure 1 This is a top view schematic diagram showing a first modified example of the electromagnetic wave detector according to Embodiment 10. Figure 2 It is along Figure 22 A cross-sectional diagram of line segment XXVI-XXVI. Figure 22 This is a top view schematic diagram showing a second variation of the electromagnetic wave detector according to Embodiment 10. Figure 22 to Figure 24 It is along Figure 22 A cross-sectional schematic diagram of line segment XXVIII-XXVIII.

[0210] Figure 23 The electromagnetic wave detector shown basically has the same characteristics as... Figure 22 to Figure 24 as well as Figure 22 to Figure 24 The electromagnetic wave detector shown has the same structure and can achieve the same effect, but the structure of the two-dimensional material layer 1 and the insulating film 3 is different. Figure 27 as well as Figure 28 The electromagnetic wave detectors shown are different. That is, Figure 25 The electromagnetic wave detector shown has a connection portion with multiple two-dimensional material layers 1 and semiconductor layers 4, which is consistent with... Figure 26 as well as Figure 22 The electromagnetic wave detectors shown are different.

[0211] exist Figure 22 In the electromagnetic wave detector shown, multiple openings are formed in the insulating film 3. A two-dimensional material layer 1 extends into the interior of each of the multiple openings and is electrically connected to the semiconductor layer 4 inside each of the multiple openings. A first opening, a second opening, and a third opening are formed in the insulating film 3 as multiple openings. The first opening, the second opening, and the third opening are arranged at intervals. The first opening, the second opening, and the third opening each penetrate the insulating film 3 and are exposed on the surface of the bottom semiconductor layer 4. The two-dimensional material layer 1 extends from the upper surface of the insulating film 3 into the interior of the first opening, the second opening, and the third opening. The two-dimensional material layer 1 contacts the semiconductor layer 4 at the bottom of the first opening, the second opening, and the third opening.

[0212] As described above, by providing multiple openings in the insulating film 3, the contact area between the two-dimensional material layer 1 and the semiconductor layer 4 is increased, which allows the current flowing from the semiconductor layer 4 to the two-dimensional material layer 1 to be dispersed. Therefore, the area in which the two-dimensional material layer 1 receives the influence of electric field changes via the ferroelectric layer 5 can be expanded.

[0213] For example, consider the case where the electromagnetic wave detector of this embodiment is used as a single pixel. For example, consider... Figure 25 The electromagnetic wave detector shown is represented by a single pixel with a planar quadrilateral shape.Figure 25 In the case where an electromagnetic wave is incident on the ferroelectric layer 5 from the side of the first electrode portion 2a, in order to reduce the attenuation of the electromagnetic wave incident on the ferroelectric layer 5, it is preferable to reduce the area of the first electrode portion 2a as much as possible. Therefore, as shown in Figure 22 and Figure 22 to Figure 24 the first electrode portion 2a is disposed at one of the four corners of the pixel. Also, as shown in Figure 27 the first, second, and third openings of the insulating film 3 are disposed at the other three corners. Thereby, it is possible to suppress the attenuation of the electromagnetic wave due to the first electrode portion 2a to the minimum, and to increase the contact area of the two-dimensional material layer 1 and the ferroelectric layer 5. As a result, it is possible to expand the region of the two-dimensional material layer 1 that receives the influence of the change in electric field from the ferroelectric layer 5, and to make the electromagnetic wave detector highly sensitive. Furthermore, the areas of the first electrode portion 2a and the opening portions of the insulating film 3 are preferably as small as possible.

[0214] In Figure 22 to Figure 24 , a plurality of connection portions to the semiconductor layer 4 are provided, but a plurality of connection portions of the two-dimensional material layer 1 and the first electrode portion 2a can also be provided as shown in Figure 27 and Figure 25 . The plurality of first electrode portions 2a are each disposed, for example, at two or more of the four corners of the pixel described above. Furthermore, the plurality of first electrode portions 2a can also be disposed at other positions on the insulating film 3 as long as they are each disposed on the insulating film 3.

[0215] In addition, a plurality of connection portions of the two-dimensional material layer 1 and the semiconductor layer 4 and a plurality of connection portions of the two-dimensional material layer 1 and the first electrode portion 2a can each be provided. For example, the connection portions of the two-dimensional material layer 1 and the semiconductor layer 4 and the connection portions of the two-dimensional material layer 1 and the first electrode portion 2a can each be disposed at two of the four corners of the pixel described above.

[0216] Figure 26 and Figure 29 the electromagnetic wave detector shown in Figure 30 has basically the same structure as the electromagnetic wave detector shown in Figure 29 , and the same effects can be obtained, but the structure of the first electrode portion 2a and the insulating film 3 is different from that of the electromagnetic wave detector shown in Figure 1 . That is, in the electromagnetic wave detector shown in Figure 2 , the first electrode portion 2a is formed in a ring shape, and the above-mentioned first portion of the two-dimensional material layer 1 is disposed more inward than the first electrode portion 2a. The first electrode portion 2a is disposed, for example, at the outer peripheral portion of the pixel described above. The opening portion of the insulating film 3 is disposed more inward than the first electrode portion 2a, and is disposed, for example, at the center of the pixel described above. The first electrode portion 2a is disposed on the upper surface of the insulating film 3 in such a manner as to surround the outer periphery of the opening portion of the insulating film 3. In the electromagnetic wave detector shown in Figure 1The electromagnetic wave detector shown has an increased photoelectric current taken out from the semiconductor layer 4 via the two-dimensional material layer 1, so the detection sensitivity is high. Further, regarding the width of the first electrode portion 2a, in order to suppress attenuation of electromagnetic waves, it is preferable to be as thin as possible. The two-dimensional material layer 1 can also be disposed in a region partially overlapping the opening portion of the insulating film 3 and the first electrode portion 2a and substantially overlapping the planar shape of the semiconductor layer 4.

[0217] Here, the structure of the electromagnetic wave detector of the present embodiment can also be applied to other embodiments.

[0218] <Effects>

[0219] In the electromagnetic wave detector shown, Figure 2 , Figure 29 In the electromagnetic wave detector shown, at least either the connecting portion of the two-dimensional material layer 1 and the semiconductor layer 4 or the connecting portion of the two-dimensional material layer 1 and the first electrode portion 2a is provided with a plurality of.

[0220] By providing at least either the connecting portion of the two-dimensional material layer 1 and the semiconductor layer 4 or the connecting portion of the two-dimensional material layer 1 and the first electrode portion 2a with a plurality of, the current flowing between the semiconductor layer 4 and the first electrode portion 2a via the two-dimensional material layer 1 does not flow locally in the two-dimensional material layer 1 but disperses. As a result, in the electromagnetic wave detector shown, Figure 1 , Figure 2 In the electromagnetic wave detector shown, compared to the case where each connecting portion is provided with only one, the region in which the current in the two-dimensional material layer 1 can change due to changes in polarization in the ferroelectric layer 5 is wider, so the detection sensitivity is high.

[0221] In the electromagnetic wave detector shown in Figure 29 and Figure 29 In the electromagnetic wave detector shown, the first electrode portion 2a is formed in a ring shape, and the above first portion of the two-dimensional material layer 1 is disposed further inward than the first electrode portion 2a. In this case, it is possible to minimize the attenuation of electromagnetic waves due to the first electrode portion 2a and to expand the region in the two-dimensional material layer 1 that receives the influence of changes in the electric field from the semiconductor layer 4. As a result, it is possible to make the electromagnetic wave detector highly sensitive.

[0222] Embodiment 11.

[0223] <Structure of electromagnetic wave detector>

[0224] Figure 30 is a cross-sectional view schematically showing an electromagnetic wave detector according to Embodiment 11. Figure 29 is a cross-sectional view schematically showing a modification of the electromagnetic wave detector according to Embodiment 11.

[0225] Figure 29 The electromagnetic wave detector shown basically has the same configuration asFigure 30 as well as Figure 31 The electromagnetic wave detector shown has the same structure and can achieve the same effect, but the structure of semiconductor layer 4 is different. Figure 32 as well as Figure 31 The electromagnetic wave detectors shown are different. That is, Figure 1 The electromagnetic wave detector shown relates to semiconductor layer 4, which includes semiconductor layer 4a (first semiconductor portion) and semiconductor layer 4b (second semiconductor portion), and... Figure 2 as well as Figure 1 The electromagnetic wave detectors shown are different.

[0226] like Figure 2 As shown, semiconductor layer 4 includes, for example, semiconductor layers 4a and 4b. Furthermore, semiconductor layer 4 may also include three or more semiconductor layers. Semiconductor layer 4a is exposed in the opening of the insulating film 3 and is electrically connected to the first electrode portion 2a via the two-dimensional material layer 1. Semiconductor layer 4a is, for example, in contact with the two-dimensional material layer 1 and the insulating film 3. Semiconductor layer 4b is, for example, disposed on the side opposite to semiconductor layer 4a and the two-dimensional material layer 1, and is electrically connected to the second electrode portion 2b. Furthermore, semiconductor layers 4a and 4b in… Figure 31 Mid-layer stacking, but not limited to this.

[0227] The conductivity type of semiconductor layer 4a is different from that of semiconductor layer 4b. For example, semiconductor layer 4a has an n-type conductivity, while semiconductor layer 4b has a p-type conductivity. Therefore, semiconductor layer 4 constitutes a diode. For example, semiconductor layer 4 can constitute a photodiode that is sensitive to wavelengths different from those of the ferroelectric layer 5.

[0228] in addition, Figure 1 The electromagnetic wave detector shown basically has the same characteristics as... Figure 2 The electromagnetic wave detector shown has the same structure and achieves the same effect. However, in addition to the second electrode 2ba electrically connected to the semiconductor layer 4b (the second semiconductor portion), it also has a fourth electrode electrically connected to the semiconductor layer 4a (the first semiconductor portion). Figure 31 The electromagnetic wave detectors shown are different.

[0229] The two-dimensional material layer 1 is electrically connected to semiconductor layers 4a and 4b. The interface between semiconductor layers 4a and 4b is disposed within the aforementioned opening of the insulating film 3. Semiconductor layer 4a is in contact with, for example, the two-dimensional material layer 1 and the fourth electrode portion 2bb. Semiconductor layer 4b is in contact with, for example, the two-dimensional material layer 1 and the insulating film 3, except for the second electrode portion 2b.

[0230] like Figure 31As shown, a voltage V2 is applied between the 2nd electrode portion 2ba and the 4th electrode portion 2bb. At this time, by applying the voltage V2 in a reverse bias, a depletion layer is formed at the interface of the semiconductor layer 4a and the semiconductor layer 4b, so a depletion layer is formed at the interface of the two-dimensional material layer 1 and the semiconductor layer 4a and the semiconductor layer 4b.

[0231] Here, the structure of the electromagnetic wave detector of the present embodiment can also be applied to other embodiments.

[0232] <Effects>

[0233] In the above electromagnetic wave detector, the semiconductor layer 4 includes the semiconductor layer 4a and the semiconductor layer 4b. By forming a pn junction with the semiconductor layer 4a and the semiconductor layer 4b, the dark current can be reduced. In addition, by configuring a photodiode having sensitivity to wavelengths different from the ferroelectric layer 5 with the semiconductor layer 4a and the semiconductor layer 4b, a wideband wavelength can be detected with the ferroelectric layer 5 and the above photodiode.

[0234] Embodiment 12.

[0235] <Structure of electromagnetic wave detector>

[0236] Figure 32 is a cross-sectional view schematically showing an electromagnetic wave detector according to Embodiment 12. Figure 31 is a cross-sectional view schematically showing a modification of the electromagnetic wave detector according to Embodiment 12.

[0237] Figure 31 The electromagnetic wave detector shown basically has the same structure as Figure 32 and Figure 31 the electromagnetic wave detector shown in FIG. 1, and the same effects can be obtained, but the structure of the ferroelectric layer 5 is different from Figure 31 and Figure 32 the electromagnetic wave detector shown in FIG. 1. That is, Figure 1 the electromagnetic wave detector shown in FIG. 1 differs in that the ferroelectric layer 5 includes the ferroelectric layer 5a (1st ferroelectric portion) and the ferroelectric layer 5b (2nd ferroelectric portion). Figure 2 and Figure 33 the electromagnetic wave detector shown in FIG. 1.

[0238] As described above, the materials that constitute the ferroelectric layer 5a and the ferroelectric layer 5b are each an arbitrary ferroelectric that generates a polarization change in response to a change in thermal energy, but it is preferable that the absorption wavelengths of the electromagnetic waves be different from each other.

[0239] As Figure 33As shown, the ferroelectric layer 5 includes, for example, a ferroelectric layer 5a and a ferroelectric layer 5b. In addition, the ferroelectric layer 5 can include three or more ferroelectric layers. The ferroelectric layer 5a is disposed on the side of the two-dimensional material layer 1 relative to the ferroelectric layer 5b and is in contact with the two-dimensional material layer 1. The ferroelectric layer 5b is in contact with the ferroelectric layer 5a but is not in contact with the two-dimensional material layer 1. In addition, the ferroelectric layer 5a and the ferroelectric layer 5b are stacked in the middle but are not limited thereto. Figure 1

[0240] Figure 2 The electromagnetic wave detector shown basically has the same structure as the electromagnetic wave detector shown in Figure 1 and can achieve the same effects, but the structure of the ferroelectric layer 5 is different from that of the electromagnetic wave detector shown in Figure 2 . That is, the electromagnetic wave detector shown in Figure 33 is different from the electromagnetic wave detector shown in Figure 1 in that the ferroelectric layer 5a and the ferroelectric layer 5b are in contact with the two-dimensional material layer 1.

[0241] The ferroelectric layer 5a is disposed so as to overlap the above-mentioned first portion of the two-dimensional material layer 1. The ferroelectric layer 5b is disposed so as to overlap the above-mentioned second portion and the above-mentioned third portion of the two-dimensional material layer 1. The polarizability of the material constituting each of the ferroelectric layer 5a and the ferroelectric layer 5b is different from each other. Preferably, the polarizability of the material constituting each of the ferroelectric layer 5a and the ferroelectric layer 5b is designed so that the Fermi level in each region of the two-dimensional material layer 1 becomes optimal. For example, the polarizability of the material constituting the ferroelectric layer 5a is set to be higher than the polarizability of the material constituting the ferroelectric layer 5b.

[0242] <Effects>

[0243] In the above-mentioned electromagnetic wave detector, the ferroelectric layer 5 includes the ferroelectric layer 5a and the ferroelectric layer 5b. In the electromagnetic wave detector shown in Figure 2 , the absorption wavelength of electromagnetic waves of the ferroelectric layer 5a and the ferroelectric layer 5b is different from each other, so that a wide frequency band of wavelengths can be detected compared to a case where the absorption wavelength of electromagnetic waves of the material constituting each of the ferroelectric layer 5a and the ferroelectric layer 5b is equal to each other. In the electromagnetic wave detector shown in Figure 33 , the polarizability of the material constituting each of the ferroelectric layer 5a and the ferroelectric layer 5b is different from each other, so that it can be designed so that the Fermi level in each region of the two-dimensional material layer 1 becomes optimal. By optimally designing the Fermi level in each region of the two-dimensional material layer 1, high performance of the electromagnetic wave detector is achieved.

[0244] Embodiment 13.

[0245] <Structure of electromagnetic wave detector>

[0246] ​In the electromagnetic wave detector according to the present embodiment, the two-dimensional material layer 1 includes a region corresponding to the channel region as a disorder layer structure portion Figure 33 and Figure 33 different from the electromagnetic wave detector shown in FIGS. 1 to 3.

[0247] In the electromagnetic wave detector described above, the region in the two-dimensional material layer 1 corresponding to the channel region becomes a disorder layer structure portion. Here, the disorder layer structure refers to a structure in which a plurality of graphenes are stacked and the lattices of the stacked graphenes do not match each other. Further, the entire two-dimensional material layer 1 can be a disorder layer structure, or only a part thereof can be a disorder layer structure.

[0248] As a method of producing the disorder layer structure portion, any method can be used. For example, the disorder layer structure portion can be formed by transferring a single-layer graphene produced by a CVD method multiple times and stacking a plurality of graphenes. Alternatively, the disorder layer structure portion can be formed by growing graphenes on a graphene using ethanol or methane as a carbon source by a CVD method. By making the contact region with the insulating film 3 in the two-dimensional material layer 1 a disorder layer structure, the mobility of carriers in the two-dimensional material layer 1 is increased. Here, a normally stacked graphene is called A-B stacking in which the lattices of the stacked graphenes match each other. However, the graphene produced by a CVD method is polycrystalline, and in a case where the graphene is further transferred multiple times on the graphene or a case where the graphene is stacked on the graphene of the substrate using a CVD method, a disorder layer structure in which the lattices of the stacked graphenes do not match each other is formed.

[0249] The graphene of the disorder layer structure has less influence of interaction between layers and has properties equivalent to those of a single-layer graphene. Further, the two-dimensional material layer 1 is affected by carrier scattering in the insulating film 3 serving as a substrate, and the mobility is decreased. However, in the graphene of the disorder layer structure, the graphene in contact with the insulating film 3 is affected by carrier scattering, but the upper graphene stacked on the graphene in the disorder layer structure is less likely to be affected by carrier scattering in the insulating film 3 of the substrate. Further, in the graphene of the disorder layer structure, the influence of interaction between layers is small, and thus the conductivity is also increased. According to the above, the mobility of carriers can be increased in the graphene of the disorder layer structure. As a result, the sensitivity of the electromagnetic wave detector can be increased.

[0250] Further, the graphene of the disorder layer structure can be applied only to a part of the two-dimensional material layer 1 present on the insulating film 3. For example, in the contact region with the semiconductor layer 4 or the contact region with the first electrode portion 2a in the two-dimensional material layer 1, a graphene that is not a disorder layer structure, such as a single-layer graphene, can be used. In this case, it is not necessary to increase the contact resistance of the first electrode portion 2a and the two-dimensional material layer 1 and the semiconductor layer 4, and the influence of carrier scattering in the insulating film 3 on the two-dimensional material layer 1 can be suppressed.

[0251] Here, the structure of the electromagnetic wave detector in this embodiment can also be applied to other embodiments.

[0252] <Effects>

[0253] In the aforementioned electromagnetic wave detector, the two-dimensional material layer 1 comprises a disordered layer structure. In this case, the carrier mobility in the two-dimensional material layer 1 can be increased. As a result, the sensitivity of the electromagnetic wave detector can be improved.

[0254] Implementation method 14.

[0255] <Structure of an Electromagnetic Wave Detector>

[0256] Figure 34 This is a cross-sectional schematic diagram of the electromagnetic wave detector involved in Embodiment 14.

[0257] Figure 34 The electromagnetic wave detector shown basically has the same characteristics as... Figure 1 as well as Figure 2 The electromagnetic wave detector shown has the same structure and can achieve the same effect, but the structure on the two-dimensional material layer 1 is different. Figure 1 as well as Figure 2 The electromagnetic wave detector shown is different. That is, in Figure 34 In the electromagnetic wave detector shown, at least one conductor 7 is formed on the upper surface of the two-dimensional material layer 1, which is related to... Figure 1 as well as Figure 2 The electromagnetic wave detector shown is different. Multiple conductors 7 are disposed on the upper surface of the two-dimensional material layer 1. The multiple conductors 7 are arranged at intervals from each other. The conductors 7 are floating electrodes. This will be explained in detail below.

[0258] like Figure 34 As shown, the electromagnetic wave detector according to this embodiment has a conductor 7 serving as a floating electrode disposed on a two-dimensional material layer 1. The material constituting the conductor 7 can be any material as long as it is a conductor. For example, metals such as gold (Au), silver (Ag), copper (Cu), aluminum (Al), nickel (Ni), chromium (Cr), or palladium (Pd) can be used as the material for the conductor 7. Here, the conductor 7 is not connected to a power supply circuit or the like, and is thus floating.

[0259] Conductors 7 are disposed on a two-dimensional material layer 1 located between the first electrode portion 2a and the semiconductor layer 4. The plurality of conductors 7 have a one-dimensional or two-dimensional periodic structure. For example, as an example of a one-dimensional periodic structure, a material layer 1 can be used... Figure 35the horizontal direction of the paper or the depth direction of the paper. In addition, as an example of a two-dimensional periodic configuration, a configuration in which the conductive bodies 7 are arranged at positions corresponding to lattice points of a square lattice or a triangular lattice or the like in a plan view of the electromagnetic wave detector can be employed. In addition, the planar shape of each conductive body 7 can be any shape such as a circular shape, a triangular shape, a quadrangular shape, a polygonal shape, or an elliptical shape, and the like in a plan view. In addition, the arrangement of the conductive bodies 7 in a plan view is not limited to an arrangement having the above-described periodic symmetry, and can be an arrangement having asymmetry in a plan view. Here, the specific method of forming the conductive bodies 7 can employ any method, but for example, the same method as the manufacturing method of the first electrode portion 2a described in Embodiment 1 can be used.

[0260] In the electromagnetic wave detector according to the present embodiment, the conductive bodies 7 serving as floating electrodes are provided on the two-dimensional material layer 1. Therefore, surface carriers generated in the ferroelectric layer 5 by irradiation of electromagnetic waves can move back and forth between the plurality of conductive bodies 7, as a result of which the lifetime of the photo-carriers is lengthened. Thus, the sensitivity of the electromagnetic wave detector can be improved.

[0261] In addition, by arranging the plurality of conductive bodies 7 in a configuration constituting a one-dimensional periodicity and making the material of the conductive bodies 7 a material that generates surface plasmon resonance, polarization dependence is generated in the conductive bodies 7 by the irradiated electromagnetic waves. As a result, only electromagnetic waves of a specific polarization can be irradiated to the semiconductor layer 4 of the electromagnetic wave detector. In this case, the electromagnetic wave detector according to the present embodiment can detect only light of a specific polarization.

[0262] In addition, by arranging the plurality of conductive bodies 7 in a configuration constituting a two-dimensional periodicity and making the material of the conductive bodies 7 a material that generates surface plasmon resonance, electromagnetic waves of a specific wavelength can be resonated by the plurality of conductive bodies 7. In this case, the electromagnetic wave detector can detect only electromagnetic waves having a specific wavelength. In this case, the electromagnetic wave detector according to the present embodiment can detect only electromagnetic waves of a specific wavelength with high sensitivity.

[0263] In addition, in a case where the plurality of conductive bodies 7 are formed in a configuration that is asymmetric in a plan view, polarization dependence is generated in the conductive bodies 7 with respect to the irradiated electromagnetic waves, similarly to the case where the plurality of conductive bodies 7 are made into a one-dimensional periodic configuration. As a result, only electromagnetic waves of a specific polarization can be irradiated to the semiconductor layer 4. In this case, the electromagnetic wave detector according to the present embodiment can detect only light of a specific polarization.

[0264] In addition, the above-described electromagnetic wave detector can be configured to have the conductive bodies 7 under the two-dimensional material layer 1. With such a structure, the same effects asFigure 36 The electromagnetic wave detector shown above has the same effect. Furthermore, in this case, the two-dimensional material layer 1 is not damaged when the conductive body 7 is formed, so the mobility of the carriers in the two-dimensional material layer 1 can be suppressed from decreasing.

[0265] In addition, a concave-convex portion can be formed in the two-dimensional material layer 1. In this case, the concave-convex portion of the two-dimensional material layer 1 can be configured to be periodic or asymmetric, similarly to the plurality of conductive bodies 7 described above. In this case, the same effect as in the case where the plurality of conductive bodies 7 are formed can be obtained.

[0266] Here, the structure of the electromagnetic wave detector of the present embodiment can also be applied to other embodiments.

[0267] <Effects>

[0268] The electromagnetic wave detector described above further includes one or more conductive bodies 7. The one or more conductive bodies 7 are configured to be in contact with the two-dimensional material layer 1. In this case, the lifetime of the photo-carriers in the two-dimensional material layer 1 is lengthened. As a result, the sensitivity of the electromagnetic wave detector can be improved.

[0269] Embodiment 15.

[0270] <Structure of electromagnetic wave detector>

[0271] Figure 35 is a cross-sectional view of an electromagnetic wave detector according to Embodiment 15.

[0272] Figure 1 The electromagnetic wave detector shown above basically includes the same structure as Figure 2 and Figure 1 and can obtain the same effect, but the structure on the two-dimensional material layer 1 is different from that of the electromagnetic wave detectors shown in Figure 2 and Figure 35 . That is, in the electromagnetic wave detector shown in Figure 36 , at least one or more contact layers 8 are formed on the upper surface of the two-dimensional material layer 1, which is different from the electromagnetic wave detectors shown in Figure 35 and Figure 35 . Hereinafter, a detailed description will be given.

[0273] In the electromagnetic wave detector shown in Figure 36 , the contact layer 8 is provided on the two-dimensional material layer 1. The contact layer 8 is composed of a material that can supply holes or electrons to the two-dimensional material layer 1 by being in contact with the two-dimensional material layer 1. The two-dimensional material layer 1 can be arbitrarily doped with holes or electrons by the contact layer 8.

[0274] As the contact layer 8, for example, a composition called a positive photoresist containing a photosensitizer having a benzoquinone diazine farm base and an ester aldehyde resin can be used. In addition, as the material constituting the contact layer 8, for example, a material having a polar group can be used. For example, a material having an electron-withdrawing group as one example of the material has an effect of reducing the electron density of the two-dimensional material layer 1. In addition, a material having an electron-donating group as one example of the material has an effect of increasing the electron density of the two-dimensional material layer 1. As the material having an electron-withdrawing group, for example, a material having a halogen, a nitrile, a carboxyl group, or a carbonyl group, or the like can be cited. In addition, as the material having an electron-donating group, for example, a material having an alkyl group, an alcohol, an amino group, or a hydroxyl group, or the like can be cited. In addition, in addition to the above, a material in which a charge is shifted in the entire molecule by a polar group can also be used as the material of the contact layer 8.

[0275] In addition, even in an organic substance, a metal, a semiconductor, an insulator, a two-dimensional material, or any mixture of these materials, as long as it is a material in which a charge is shifted within a molecule to generate polarity, it can be used as the material of the contact layer 8. Here, in the case where the contact layer 8 composed of an inorganic substance is brought into contact with the two-dimensional material layer 1, the conduction type in which the two-dimensional material layer 1 is doped is p-type in the case where the work function of the contact layer 8 is greater than the work function of the two-dimensional material layer 1, and is n-type in the case where the work function of the contact layer 8 is less than the work function of the two-dimensional material layer 1. In contrast to this, in the case where the contact layer 8 is an organic substance, the organic substance as the material constituting the contact layer 8 does not have a definite work function. Therefore, as to whether the two-dimensional material layer 1 becomes n-type doping or p-type doping, it is preferable to judge the polar group of the material of the contact layer 8 in accordance with the polarity of the molecule of the organic substance used in the contact layer 8.

[0276] For example, in the case where, as the contact layer 8, a composition called a positive photoresist containing a photosensitizer having a benzoquinone diazine farm base and an ester aldehyde resin is used, the region in which a resist is formed in the two-dimensional material layer 1 by a photolithography process becomes a p-type two-dimensional material layer region. Thereby, the mask forming process in contact with the surface of the two-dimensional material layer 1 becomes unnecessary. As a result, it is possible to reduce the process damage to the two-dimensional material layer 1 and to simplify the process.

[0277] The electromagnetic wave detector according to the present embodiment is provided with the contact layer 8 on the two-dimensional material layer 1. As described above, by using, for example, a material having an electron-withdrawing group or a material having an electron-donating group as the material of the contact layer 8, it is possible to intentionally make the state (conduction type) of the two-dimensional material layer 1 n-type or p-type. In this case, without taking into account the influence of carrier doping from the polarization of the first electrode portion 2a and the semiconductor layer 4 and the ferroelectric layer 5, it is possible to suppress the carrier doping of the two-dimensional material layer 1. As a result, it is possible to improve the performance of the electromagnetic wave detector.

[0278] In addition, by forming the contact layer 8 on only one of the first electrode portion 2a side or the semiconductor layer 4 side in the upper surface of the two-dimensional material layer 1, a gradient of charge density is formed in the two-dimensional material layer 1. As a result, the mobility of the carriers in the two-dimensional material layer 1 is increased, and the electromagnetic wave detector can be made highly sensitive.

[0279] In addition, a plurality of contact layers 8 can be formed on the two-dimensional material layer 1. The number of contact layers 8 can be three or more, and can be any number. The plurality of contact layers 8 can be formed on the two-dimensional material layer 1 between the first electrode portion 2a and the semiconductor layer 4. In this case, the materials of the plurality of contact layers 8 can be the same material or different materials.

[0280] In addition, in the electromagnetic wave detector according to the present embodiment, the film thickness of the contact layer 8 is preferably sufficiently thin to enable photoelectric conversion in a case where electromagnetic waves are irradiated onto the two-dimensional material layer 1. On the other hand, the contact layer 8 is preferably formed to have a thickness that dopes carriers into the two-dimensional material layer 1 from the contact layer 8. The contact layer 8 can have any structure as long as carriers such as molecules or electrons are introduced into the two-dimensional material layer 1. For example, the two-dimensional material layer 1 can be doped with carriers by immersing the two-dimensional material layer 1 in a solution and supplying carriers to the two-dimensional material layer 1 at the molecular level, without forming a solid contact layer 8 on the two-dimensional material layer 1.

[0281] In addition, as the material of the contact layer 8, a material that causes polarity inversion can be used in addition to the above-described materials. In this case, if the contact layer 8 inverts the polarity, electrons or holes generated at the time of inversion are supplied to the two-dimensional material layer 1. Therefore, the two-dimensional material layer 1 in the portion in contact with the contact layer 8 is doped with electrons or holes. Therefore, even if the contact layer 8 is removed, the portion of the two-dimensional material layer 1 in contact with the contact layer 8 is in a state of being doped with electrons or holes as it is. Therefore, in a case where a material that causes polarity inversion is used as the contact layer 8, the contact layer 8 can be removed from the two-dimensional material layer 1 after a certain period of time has elapsed. In this case, the opening area of the two-dimensional material layer 1 increases compared to a case where the contact layer 8 is present. Therefore, the detection sensitivity of the electromagnetic wave detector can be improved. Here, polarity inversion refers to a phenomenon in which a polar group chemically inverts, such as a phenomenon in which an electron-withdrawing group changes to an electron-donating group or an electron-donating group changes to an electron-withdrawing group or a polar group changes to a nonpolar group or a nonpolar group changes to a polar group.

[0282] Alternatively, the contact layer 8 can be formed using a material that undergoes a polarity change upon irradiation with electromagnetic waves. In this case, by selecting a material that undergoes a polarity change at a specific wavelength of electromagnetic waves as the material of the contact layer 8, it is possible to induce a polarity change in the contact layer 8 only upon irradiation with electromagnetic waves at a specific wavelength, thereby doping the two-dimensional material layer 1. As a result, the photocurrent flowing into the two-dimensional material layer 1 can be increased.

[0283] Alternatively, a material that undergoes a redox reaction when irradiated by electromagnetic waves can be used as the material for contact layer 8. In this case, electrons or holes generated during the redox reaction can be doped into the two-dimensional material layer 1.

[0284] Here, the structure of the electromagnetic wave detector in this embodiment can also be applied to other embodiments.

[0285] <Effects>

[0286] The aforementioned electromagnetic wave detector includes a contact layer 8 that contacts the two-dimensional material layer 1. The contact layer 8 supplies holes or electrons to the two-dimensional material layer 1. In this case, the carrier doping of the two-dimensional material layer 1 can be controlled without considering the influence of carrier doping from the first electrode portion 2a and the semiconductor layer 4. As a result, the performance of the electromagnetic wave detector can be improved.

[0287] Implementation method 16.

[0288] <Structure of an Electromagnetic Wave Detector>

[0289] Figure 36 This is a cross-sectional schematic diagram of the electromagnetic wave detector involved in Embodiment 16. Figure 37 This is a cross-sectional schematic diagram showing a modified example of the electromagnetic wave detector according to Embodiment 16. Figure 37 The electromagnetic wave detector shown basically has the same characteristics as... Figure 1 as well as Figure 2 The electromagnetic wave detector shown has the same structure and achieves the same effect, but differs in that it has gaps 9 formed around the two-dimensional material layer 1. Figure 1 as well as Figure 2 The electromagnetic wave detectors shown are different.

[0290] like Figure 37As shown, a gap 9 is provided between the two-dimensional material layer 1 and the insulating film 3. The two-dimensional material layer 1 has a surface facing the gap 9. That is, unlike the electromagnetic wave detector involved in Embodiment 1, the two-dimensional material layer 1 is not in contact with the insulating film 3. At this time, at the opening, the upper surface of the semiconductor layer 4 is preferably at the same height as the upper surface of the first electrode portion 2a. The two-dimensional material layer 1 extends from the first electrode portion 2a to the semiconductor layer 4. The gap 9 located below the two-dimensional material layer 1 is located between the first electrode portion 2a and the opening. Furthermore, other structures can be adopted as long as the gap 9 is provided between the insulating film 3 and the two-dimensional material layer 1.

[0291] Figure 38 The electromagnetic wave detector shown basically has the same characteristics as... Figure 39 The electromagnetic wave detector shown has the same structure and can achieve the same effect, but the construction of the two-dimensional material layer 1 is different from that of the electromagnetic wave detector shown. Figure 38 The electromagnetic wave detector shown is different. That is, in Figure 38 In the electromagnetic wave detector shown, a gap 9 is formed between the two-dimensional material layer 1 and the ferroelectric layer 5.

[0292] like Figure 38 As shown, a gap 9 is provided between the two-dimensional material layer 1 and the ferroelectric layer 5. That is, unlike the electromagnetic wave detector involved in Embodiment 1, the two-dimensional material layer 1 is not in contact with the ferroelectric layer 5. The polarization change of the ferroelectric layer 5 generated by electromagnetic wave irradiation produces an electric field change in the two-dimensional material layer 1 via the first electrode portion 2a or the semiconductor layer 4. At this time, the polarization direction of the ferroelectric layer 5 can also be a direction parallel to the surface of the two-dimensional material layer 1. Alternatively, an electric field change can be generated through the gap 9. At this time, the polarization direction of the ferroelectric layer 5 can also be a direction perpendicular to the surface of the two-dimensional material layer 1. In addition, the upper surface of the semiconductor layer 4 is preferably at the same height as the upper surface of the first electrode portion 2a. The two-dimensional material layer 1 extends from the first electrode portion 2a to the semiconductor layer 4. The gap 9 located below the two-dimensional material layer 1 is located between the first electrode portion 2a and the semiconductor layer 4. Furthermore, other structures can be adopted as long as the gap 9 is provided between the two-dimensional material layer 1 and the ferroelectric layer 5.

[0293] Here, the structure of the electromagnetic wave detector in this embodiment can also be applied to other embodiments.

[0294] <Effects>

[0295] In the electromagnetic wave detector described above, the void 9 is formed in at least one of the upper portion or the lower portion of the two-dimensional material layer 1. In this case, the influence of the scattering of the carriers accompanying the contact of the insulating film 3 or the ferroelectric layer 5 and the two-dimensional material layer 1 can be eliminated. As a result, the reduction in the mobility of the carriers in the two-dimensional material layer 1 can be suppressed. Therefore, the sensitivity of the electromagnetic wave detector can be improved. Furthermore, the photogating effect can function even when the void 9 is generated in the lower portion of the two-dimensional material layer 1.

[0296] Embodiment 17.

[0297] Structure of electromagnetic wave detector

[0298] Figure 39 is a cross-sectional view schematically showing the electromagnetic wave detector according to Embodiment 17. Figure 38 The electromagnetic wave detector shown basically has the same structure as the electromagnetic wave detector shown in Figure 38 and Figure 39 and can obtain the same effects, but differs from the electromagnetic wave detector shown in Figure 39 and Figure 39 in that it further has the connection conductor portion 2e that electrically connects the two-dimensional material layer 1 and the ferroelectric layer 5, and the ferroelectric layer 5 is connected to the two-dimensional material layer 1 via the connection conductor portion 2e.

[0299] The ferroelectric layer 5 is disposed so as to generate a change in the polarization of the ferroelectric layer 5 due to the irradiation of electromagnetic waves in a direction perpendicular to the interface of the junction of the two-dimensional material layer 1 and the connection conductor portion 2e. In this case, the electric charge generated in the ferroelectric layer 5 by the change in the polarization described above is injected into the two-dimensional material layer 1 via the connection conductor portion 2e.

[0300] ​ The connection conductor portion 2e and the ferroelectric layer 5 shown are disposed in the upper portion of the two-dimensional material layer 1. Furthermore, the connection conductor portion 2e and the ferroelectric layer 5 can also be disposed in the lower portion of the two-dimensional material layer 1. In this case, the connection conductor portion 2e is disposed, for example, in the upper portion of the ferroelectric layer 5. The ferroelectric layer 5 is disposed so as to generate a change in the polarization of the ferroelectric layer 5 due to the irradiation of electromagnetic waves in a direction perpendicular to the first face of the semiconductor layer 4.

[0301] The connection conductor portion 2e and the ferroelectric layer 5 can also be arranged in alignment with the two-dimensional material layer 1 in a direction along the first face and orthogonal to the direction of extension of the two-dimensional material layer 1. In this case, it is preferable that the ferroelectric layer 5 be disposed so as to generate a change in the polarization of the ferroelectric layer 5 due to the irradiation of electromagnetic waves in a direction along the two-dimensional face of the two-dimensional material layer 1. In other words, the ferroelectric layer 5 is disposed so as to generate a change in the polarization of the ferroelectric layer 5 due to the irradiation of electromagnetic waves in a direction along the first face of the semiconductor layer 4.

[0302] <Effects of Actions>

[0303] The surface resistance of the two-dimensional material layer 1 and the ferroelectric layer 5 is high. Therefore, in a case where the ferroelectric layer 5 is not connected to the two-dimensional material layer 1 via the connection conductor portion 2e, the electric charge generated in the ferroelectric layer 5 by the change in polarization does not flow into the two-dimensional material layer 1. In contrast, in the electromagnetic wave detector according to the present embodiment, the ferroelectric layer 5 is connected to the two-dimensional material layer 1 via the connection conductor portion 2e. Therefore, the electric charge generated in the ferroelectric layer 5 by the change in polarization accompanying the irradiation of electromagnetic waves can flow into the two-dimensional material layer 1 via the connection conductor portion 2e. As a result, in the electromagnetic wave detector according to the present embodiment, the conductivity of the two-dimensional material layer 1 can be modulated more efficiently than in an electromagnetic wave detector in which the ferroelectric layer 5 is not connected to the two-dimensional material layer 1 via the connection conductor portion 2e.

[0304] Further, in a case where the connection conductor portion 2e and the ferroelectric layer 5 are disposed on the upper portion of the two-dimensional material layer 1, in the manufacturing method of the electromagnetic wave detector, the step of forming the connection conductor portion 2e and the ferroelectric layer 5 is performed after the step of forming the two-dimensional material layer 1. Therefore, there is a possibility that the two-dimensional material layer 1 is damaged by the process in the step of forming the connection conductor portion 2e and the ferroelectric layer 5.

[0305] In contrast, in a case where the connection conductor portion 2e and the ferroelectric layer 5 are disposed on the lower portion of the two-dimensional material layer 1, in the manufacturing method of the electromagnetic wave detector, the step of forming the connection conductor portion 2e and the ferroelectric layer 5 is performed before the step of forming the two-dimensional material layer 1. Therefore, there is no possibility that the two-dimensional material layer 1 is damaged by the process in the step of forming the connection conductor portion 2e and the ferroelectric layer 5. As a result, it is possible to prevent the decrease in the performance of the two-dimensional material layer 1 and the decrease in the detection sensitivity of the electromagnetic wave detector accompanying the process damage.

[0306] In a case where the connection conductor portion 2e and the ferroelectric layer 5 are arranged on the two-dimensional material layer 1 in a direction along the first surface and orthogonal to the direction of extension of the two-dimensional material layer 1, the ferroelectric layer 5 is preferably disposed so as to generate the change in polarization of the ferroelectric layer 5 by the irradiation of electromagnetic waves in a direction along the two-dimensional surface of the two-dimensional material layer 1. The resistance in the direction along the two-dimensional surface of the two-dimensional material layer 1 is lower than the resistance in the direction perpendicular to the two-dimensional surface of the two-dimensional material layer 1. Therefore, in a case where the ferroelectric layer 5 is disposed so as to generate the change in polarization in the direction along the two-dimensional surface of the two-dimensional material layer 1, it is possible to more efficiently inject the electric charge generated in the ferroelectric layer 5 by the change in polarization accompanying the irradiation of electromagnetic waves into the two-dimensional material layer 1 via the connection conductor portion 2e than in a case where the ferroelectric layer 5 is disposed so as to generate the change in polarization in the direction perpendicular to the two-dimensional surface of the two-dimensional material layer 1.

[0307] The structure of the electromagnetic wave detector of the present embodiment can also be applied to other embodiments.

[0308] Embodiment 18.

[0309] <Structure of electromagnetic wave detector>

[0310] ​ is a top view schematic diagram of the electromagnetic wave detector according to Embodiment 18. ​ is a cross-sectional view schematic diagram showing a modification of the electromagnetic wave detector according to Embodiment 18.

[0311] ​ The electromagnetic wave detector shown is an electromagnetic wave detector assembly having a plurality of electromagnetic wave detectors 100 according to any of Embodiments 1 to 12 as detection elements. For example, the electromagnetic wave detector according to Embodiment 1 can also be used as the electromagnetic wave detector 100. In ​ In the present embodiment, the electromagnetic wave detectors 100 are arranged in an array in two dimensions. Alternatively, the plurality of electromagnetic wave detectors 100 can be arranged in a line in one dimension. Hereinafter, the details will be described.

[0312] As shown in ​ In the electromagnetic wave detector according to the present embodiment, the electromagnetic wave detectors 100 are arranged in a 2 x 2 array. However, the number of electromagnetic wave detectors 100 arranged is not limited to this. For example, a plurality of electromagnetic wave detectors 100 can be arranged in a 3 x 3 or more array. In the present embodiment, the plurality of electromagnetic wave detectors 100 are arranged periodically in two dimensions, but the plurality of electromagnetic wave detectors 100 can be arranged periodically in a certain direction. Alternatively, the plurality of electromagnetic wave detectors 100 can be arranged at different intervals rather than periodically.

[0313] In addition, when a plurality of electromagnetic wave detectors 100 are arranged in an array, the second electrode portion 2b can also be a common electrode as long as each electromagnetic wave detector 100 can be separated. By making the second electrode portion 2b a common electrode, the wiring of the pixels can be reduced compared to a structure in which the second electrode portion 2b is independent in each electromagnetic wave detector 100. As a result, the electromagnetic wave detector assembly can be made higher resolution.

[0314] The electromagnetic wave detector assembly using a plurality of electromagnetic wave detectors 100 can also be used as an image sensor by arranging a plurality of electromagnetic wave detectors 100 in an array.

[0315] In this embodiment, the electromagnetic wave detector assembly having a plurality of electromagnetic wave detectors 100 according to Embodiment 1 is described as an example, but electromagnetic wave detectors according to other embodiments can be used instead of the electromagnetic wave detectors according to Embodiment 1.

[0316] ​ The electromagnetic wave detector illustrated is an electromagnetic wave detector assembly, basically has the same structure as the electromagnetic wave detector according to ​ ​ ​ In the electromagnetic wave detector according to

[0317] In ​ , the electromagnetic wave detectors 200, 201, 202, and 203 are arranged in a 2 x 2 matrix, but the number of electromagnetic wave detectors arranged is not limited thereto. In this embodiment, the electromagnetic wave detectors 200, 201, 202, and 203 of different kinds are arranged periodically in two dimensions, but can be arranged periodically in one dimension. Alternatively, the electromagnetic wave detectors 200, 201, 202, and 203 of different kinds can be arranged at different intervals, not periodically.

[0318] In ​ the electromagnetic wave detector assembly, the electromagnetic wave detectors 200, 201, 202, and 203 of different kinds according to any of Embodiments 1 to 16 are arranged in one or two dimensions, and the electromagnetic wave detector assembly can have a function as an image sensor. For example, electromagnetic wave detectors that detect electromagnetic waves of different wavelengths, respectively, can be used as the electromagnetic wave detectors 200, 201, 202, and 203. Specifically, electromagnetic wave detectors having different wavelength selectivity, respectively, can be prepared from the electromagnetic wave detectors according to any of Embodiments 1 to 16, and arranged in an array. In this case, the electromagnetic wave detector assembly can detect electromagnetic waves of at least two or more different wavelengths.

[0319] By arranging the electromagnetic wave detectors 200, 201, 202, and 203 of different wavelengths in an array, the wavelength of an electromagnetic wave can be identified in any wavelength region, such as the wavelength region of ultraviolet light, infrared light, terahertz waves, electric waves, and the like, as with an image sensor used in the visible light region. As a result, for example, a colorized image in which the difference in wavelength is expressed as a difference in color can be obtained. ​​

[0320] Further, as the constituent material of the semiconductor layer 4 and the ferroelectric layer 5 constituting the electromagnetic wave detector, a material that detects different wavelengths can be used. For example, a semiconductor material that detects a wavelength of visible light and a semiconductor material that detects a wavelength of infrared light can be used as the above-mentioned constituent material. In this case, for example, when the electromagnetic wave detector is applied to an in-vehicle sensor, the electromagnetic wave detector can be used as a camera for visible light images during the day. Further, the electromagnetic wave detector can also be used as an infrared camera at night. Thus, it is not necessary to separately use a camera having an image sensor according to the detection wavelength of electromagnetic waves.

[0321] Further, as the use of the electromagnetic wave detector other than the image sensor, for example, the electromagnetic wave detector can be used as a position detection sensor that can perform position detection of an object even with a small number of pixels. For example, by the configuration of the electromagnetic wave detector assembly, if electromagnetic wave detectors 200, 201, 202, 203 that detect different wavelengths are used as described above, an image sensor that detects the intensity of electromagnetic waves of a plurality of wavelengths can be obtained. Thus, it is not necessary to use a color filter that has been necessary in a CMOS image sensor or the like in the past, and a color image can be obtained by detecting electromagnetic waves of a plurality of wavelengths.

[0322] Further, it is also possible to form a polarization recognition image sensor by arraying electromagnetic wave detectors 200, 201, 202, 203 that detect different polarizations. For example, four pixels that detect polarization angles of 0°, 90°, 45°, and 135° are taken as one unit, and the electromagnetic wave detectors of the one unit are arranged a plurality of times, whereby polarization imaging can be performed. By the polarization recognition image sensor, for example, recognition of artificial and natural objects, material recognition, recognition of the same temperature objects in the infrared wavelength region, recognition of the boundary between objects, or improvement of equivalent resolution, or the like can be achieved.

[0323] According to the above, the electromagnetic wave detector assembly according to the present embodiment configured as described above can detect electromagnetic waves of a wide wavelength region. Further, the electromagnetic wave detector assembly according to the present embodiment can detect electromagnetic waves of different wavelengths.

[0324] <Effects>

[0325] The above-mentioned electromagnetic detector assembly has a plurality of electromagnetic wave detectors. The plurality of electromagnetic wave detectors 200, 201, 202, 203 can be electromagnetic wave detectors of different kinds. For example, the plurality of electromagnetic wave detectors 200, 201, 202, 203 can detect different wavelengths, respectively. In this case, different wavelengths of electromagnetic waves can be detected by one electromagnetic wave detector assembly.

[0326] Further, in each of the above-described embodiments, as the material of the insulating film 3 or the contact layer 8 or the semiconductor layer 4, a material that changes a characteristic by irradiation of electromagnetic waves and provides a change in potential to the two-dimensional material layer 1 can also be used.

[0327] Here, as the material that changes a characteristic by irradiation of electromagnetic waves and provides a change in potential to the two-dimensional material layer 1, for example, a quantum dot, a ferroelectric material, a liquid crystal material, a fullerene, a rare earth oxide, a semiconductor material, a pn junction material, a metal-semiconductor junction material, or a metal-insulator-semiconductor junction material, or the like can be used. For example, in a case where, as the ferroelectric material, a ferroelectric material having a polarization effect (pyroelectric effect) by electromagnetic waves is used, by irradiation of electromagnetic waves, a change in polarization is generated in the ferroelectric material. As a result, a change in potential can be provided to the two-dimensional material layer 1.

[0328] In a case where, as the material of the insulating film 3 or the like, the above-described material is used, the insulating film 3 or the contact layer 8 or the semiconductor layer 4 changes a characteristic by irradiation of electromagnetic waves. As a result, a change in potential can be provided to the two-dimensional material layer 1.

[0329] Further, while an example in which a material that changes a characteristic by irradiation of electromagnetic waves and provides a change in potential to the two-dimensional material layer 1 is applied to the insulating film 3 or the contact layer 8 or the semiconductor layer 4 is described, a material that changes a characteristic by irradiation of electromagnetic waves and provides a change in potential to the two-dimensional material layer 1 can be applied to at least one or more of the above-described components. For example, in a case where a material that changes a characteristic by irradiation of electromagnetic waves and provides a change in potential to the two-dimensional material layer 1 is applied to the contact layer 8, the contact layer 8 does not necessarily have to be in direct contact with the two-dimensional material layer 1. For example, as long as a change in potential can be provided to the two-dimensional material layer 1, the contact layer 8 can be provided on the upper surface or the lower surface of the two-dimensional material layer 1 with an insulating film or the like interposed therebetween.

[0330] The embodiments disclosed this time are to be considered as illustrative and not restrictive in all points. The embodiments disclosed this time can be combined with at least two of the embodiments disclosed this time as long as there is no contradiction. The scope of the disclosure is indicated not by the above description but by the claims, and it is intended to include all modifications equivalent in meaning and scope to the claims.

Claims

1. An electromagnetic wave detector comprising: a semiconductor layer; a two-dimensional material layer electrically connected to the semiconductor layer; a first electrode portion electrically connected to the two-dimensional material layer without passing through the semiconductor layer; a second electrode portion electrically connected to the two-dimensional material layer via the semiconductor layer; and a ferroelectric layer, wherein the two-dimensional material layer includes a first portion electrically connected to the semiconductor layer, a second portion in contact with the first electrode portion, and a third portion electrically connecting the first portion and the second portion, the ferroelectric layer is disposed in contact with at least either of the first portion and the third portion of the two-dimensional material layer or is disposed apart from the two-dimensional material layer and overlaps at least a portion of the two-dimensional material layer, and the ferroelectric layer is disposed apart from the two-dimensional material layer in a manner that changes a resistance value of the two-dimensional material layer when a polarization in the ferroelectric layer changes.

2. The electromagnetic wave detector according to claim 1, further comprising an insulating film in contact with a portion of the semiconductor layer and having an opening portion that opens another portion of the semiconductor layer, wherein the two-dimensional material layer is electrically connected to the other portion of the semiconductor layer at the opening portion and extends from the opening portion to the insulating film.

3. The electromagnetic wave detector according to claim 1, further comprising an insulating film that separates at least a portion of the two-dimensional material layer and the ferroelectric layer.

4. The electromagnetic wave detector according to claim 1, further comprising a connecting conductive portion that electrically connects the two-dimensional material layer and the ferroelectric layer, wherein the ferroelectric layer is electrically connected to the two-dimensional material layer via the connecting conductive portion.

5. The electromagnetic wave detector according to any one of claims 1 to 4, wherein the first portion is in contact with the semiconductor layer or a conductive member electrically connected to the semiconductor layer, and at least a portion of the two-dimensional material layer includes the first portion.

6. The electromagnetic wave detector according to any one of claims 1 to 4, wherein the first portion is in contact with the semiconductor layer or a conductive member electrically connected to the semiconductor layer, and at least a portion of the two-dimensional material layer includes the third portion.

7. The electromagnetic wave detector according to any one of claims 1 to 4, wherein at least a portion of the two-dimensional material layer includes only the first portion or the third portion.

8. The electromagnetic wave detector according to claim 6, wherein the first portion or the conductive member is in Schottky junction with the semiconductor layer.

9. The electromagnetic wave detector according to claim 6, wherein the first electrode portion is formed in a ring shape in plan view, and the first portion is disposed more inward than the first electrode portion.

10. The electromagnetic wave detector according to claim 6, wherein the first portion has an end portion of the two-dimensional material layer in plan view.

11. The electromagnetic wave detector according to any one of claims 1 to 4, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The ferroelectric layer is disposed on a side opposite to the semiconductor layer with respect to the two-dimensional material layer.

12. The electromagnetic wave detector according to any one of claims 1 to 4, wherein The ferroelectric layer is disposed on the semiconductor layer side with respect to the two-dimensional material layer.

13. The electromagnetic wave detector according to any one of claims 1 to 4, wherein Further provided is a third electrode portion in contact with the ferroelectric layer.

14. The electromagnetic wave detector according to any one of claims 1 to 4, wherein The semiconductor layer, the two-dimensional material layer, the first electrode portion, and the second electrode portion are disposed on the ferroelectric layer.

15. The electromagnetic wave detector according to any one of claims 1 to 4, wherein Further provided is a tunnel insulating layer disposed between the two-dimensional material layer and the semiconductor layer.

16. The electromagnetic wave detector according to claim 15, wherein A thickness of the tunnel insulating layer is set to generate a tunnel current between the two-dimensional material layer and the semiconductor layer when electromagnetic waves as a detection object are incident on the two-dimensional material layer and the ferroelectric layer.

17. The electromagnetic wave detector according to any one of claims 1 to 4, wherein Further provided is a connecting conductor portion electrically connecting between the two-dimensional material layer and the semiconductor layer.

18. The electromagnetic wave detector according to any one of claims 1 to 4, wherein A polarization direction of the ferroelectric layer is a direction perpendicular to an extension direction of the two-dimensional material layer.

19. The electromagnetic wave detector according to any one of claims 1 to 4, wherein The two-dimensional material layer includes a region in contact with the ferroelectric layer and a region in contact with the semiconductor layer, The ferroelectric layer is disposed to generate an electric field in a direction perpendicular to an extension direction of the two-dimensional material layer in at least one of the region of the two-dimensional material layer in contact with the ferroelectric layer and the region in contact with the semiconductor layer.

20. The electromagnetic wave detector according to any one of claims 1 to 4, wherein At least one of a connecting portion of the two-dimensional material layer and the first electrode portion and a connecting portion of the two-dimensional material layer and the semiconductor layer is provided with a plurality.

21. The electromagnetic wave detector according to any one of claims 1 to 4, wherein The ferroelectric layer includes a first ferroelectric portion and a second ferroelectric portion, An electromagnetic wave absorption wavelength of a material constituting the first ferroelectric portion is different from an electromagnetic wave absorption wavelength of a material constituting the second ferroelectric portion.

22. The electromagnetic wave detector according to any one of claims 1 to 4, wherein The ferroelectric layer includes a first ferroelectric portion and a second ferroelectric portion, The first ferroelectric portion and the second ferroelectric portion are each disposed to overlap at least a portion of the two-dimensional material layer, A polarizability of a material constituting the first ferroelectric portion is different from a polarizability of a material constituting the second ferroelectric portion.

23. The electromagnetic wave detector according to any one of claims 1 to 4, wherein The semiconductor layer includes a first semiconductor portion of a first conduction type and a second semiconductor portion of a second conduction type, The two-dimensional material layer is electrically connected to the first semiconductor portion, The second electrode portion is electrically connected to the two-dimensional material layer via the second semiconductor portion.

24. The electromagnetic wave detector according to claim 23, wherein The two-dimensional material layer is electrically connected to the first semiconductor portion and the second semiconductor portion, The electromagnetic wave detector further includes a fourth electrode portion electrically connected to the first semiconductor portion.

25. The electromagnetic wave detector according to any one of claims 1 to 4, wherein The two-dimensional material layer includes a portion in a turbostratic structure.

26. The electromagnetic wave detector according to any one of claims 1 to 4, wherein Further provided is one or more conductors or a contact layer disposed in contact with the two-dimensional material layer.

27. The electromagnetic wave detector according to any one of claims 1 to 4, wherein A gap is formed around the two-dimensional material layer, The two-dimensional material layer has a surface facing the gap.

28. The electromagnetic wave detector according to any one of claims 1 to 4, wherein The two-dimensional material layer contains any material selected from the group consisting of transition metal dichalcogenides, graphene, black phosphorus, silicene, germanene, and borophene.

29. The electromagnetic wave detector according to any one of claims 1 to 4, wherein The two-dimensional material layer contains any material selected from the group consisting of transition metal dichalcogenides, black phosphorus, silicene, germanene, graphene nanoribbons, and borophene.

30. The electromagnetic wave detector according to any one of claims 1 to 4, wherein The first electrode portion, the two-dimensional material layer, the semiconductor layer, and the second electrode portion are electrically connected in the order of the first electrode portion, the two-dimensional material layer, the semiconductor layer, and the second electrode portion, An electromagnetic wave to be detected is detected as a change in a current value flowing between the first electrode portion and the second electrode portion.

31. An electromagnetic wave detector array, wherein A plurality of electromagnetic wave detectors according to any one of claims 1 to 30 are provided, The plurality of electromagnetic wave detectors are arranged in at least either of a first direction and a second direction.

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