Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
  • H10F30/20—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors
  • H10F30/21—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation
  • H10F30/22—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes
  • H10F30/227—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes the potential barrier being a Schottky barrier
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
  • H10F30/20—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors
  • H10F30/21—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation
  • H10F30/28—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices being characterised by field-effect operation, e.g. junction field-effect phototransistors

Definitions

• Patent Document 1 describes an electromagnetic wave detector.
• the electromagnetic wave detector described in Patent Document 1 has a semiconductor layer, a first dielectric layer and a second dielectric layer, a first electrode and a second electrode, and a graphene layer.
• the electromagnetic wave detector described in Patent Document 1 a voltage is applied to the graphene layer via the first electrode and the second electrode.
• photocarriers are generated by photoelectric conversion.
• the generated photocarriers are amplified by the voltage applied to the graphene layer. In this way, the electromagnetic wave detector described in Patent Document 1 has increased detection sensitivity for electromagnetic waves.
• Patent Document 1 the detection sensitivity for electromagnetic waves depends on the quantum efficiency of the semiconductor layer.
• the quantum efficiency of the semiconductor layer for electromagnetic waves may be insufficient.
• This disclosure has been made in consideration of such problems in the conventional technology. This disclosure provides an electromagnetic wave detector with improved detection sensitivity.
• the electromagnetic wave detector disclosed herein comprises a graphene layer, a thermoelectric material layer, and a semiconductor layer.
• the graphene layer, the thermoelectric material layer, and the semiconductor layer are electrically connected in series. There is a Schottky junction between the graphene layer and the semiconductor layer.
• the radio wave detector disclosed herein can improve the detection accuracy of electromagnetic waves.
• FIG. 2 is a plan view of the electromagnetic wave detector 100A. 2 is a cross-sectional view of the electromagnetic wave detector 100A taken along line II-II of FIG.
• FIG. 11 is a cross-sectional view of an electromagnetic wave detector 100A according to a first modified example.
• FIG. 11 is a cross-sectional view of an electromagnetic wave detector 100A according to a second modified example.
• FIG. 11 is a cross-sectional view of an electromagnetic wave detector 100A according to a third modified example.
• FIG. 11 is a cross-sectional view of an electromagnetic wave detector 100A according to a fourth modified example.
• FIG. 13 is a cross-sectional view of an electromagnetic wave detector 100A according to a fifth modified example.
• 1 is a cross section of an electromagnetic wave detector 100B.
• thermoelectric material layer 70 For example, a band gap is formed in the thermoelectric material layer 70 by stacking two or more graphene layers.
• the size of the band gap can be adjusted by changing the number of stacked graphene layers.
• the number of graphene layers in the multi-layer graphene increases, the mobility in the channel region decreases.
• the effect of carrier scattering from the substrate is suppressed, and the noise of the electromagnetic wave detector 100A decreases. Therefore, in the electromagnetic wave detector 100A having a thermoelectric material layer 70 using multi-layer graphene, light absorption is increased, and the detection sensitivity of the electromagnetic wave is improved.
• the carriers of the n-type bismuth telluride are electrons
• the Seebeck coefficient of the n-type bismuth telluride is a negative value
• the composition of the n-type bismuth telluride is Bi2Te3-YSeY ( 0 ⁇ Y ⁇ 3).
• the thermoelectric material layer 70 may use a plurality of pairs of p-type bismuth telluride and n-type bismuth telluride connected in series with each other.
• the constituent material of the thermoelectric material layer 70 may be doped with impurities to control the p-type or n-type polarity and electrical conductivity, and the crystal grain size may be controlled.
• a bias voltage is applied to the electromagnetic wave detector 100A from the power source 110. More specifically, the power source 110 is electrically connected to the substrate 10 (semiconductor layer 11) and the electrode 60, and a bias voltage is applied so that the potential at the substrate 10 is higher than the potential at the electrode 60.
• an ammeter is connected to the electromagnetic wave detector 100A for detecting the current flowing through the substrate 10, the graphene layer 40, and the thermoelectric material layer 70. A voltmeter may be connected instead of this ammeter.
• the manufacturing method of the electromagnetic wave detector 100A includes a preparation process, a first insulating film forming process, a first electrode forming process, a graphene layer forming process, a second insulating film forming process, a second electrode forming process, and a thermoelectric material layer forming process.
• the substrate 10 is prepared.
• the first insulating film forming step is performed after the preparation step.
• the insulating film 20 is formed on the substrate 10.
• the constituent material of the insulating film 20 is deposited by, for example, a CVD (Chemical Vapor Deposition) method.
• the constituent material of the deposited insulating film 20 is patterned. This patterning forms an opening. This patterning is performed, for example, by etching using a resist pattern formed on the constituent material of the deposited insulating film 20 as a mask.
• the first electrode forming process is performed after the first insulating film forming process.
• an electrode 30 is formed on the insulating film 20.
• the second electrode forming process is performed after the first electrode forming process.
• the electrode 30 may be formed, for example, by a lift-off method, or may be formed by etching the constituent material of the electrode 30 that has been deposited by sputtering or the like using a resist pattern as a mask.
• the second electrode forming process may be performed after the first electrode forming process.
• thermoelectric conversion occurs in the thermoelectric material layer 70
• the resistance value of the thermoelectric material layer 70 changes, and therefore, when a change occurs in the bias voltage applied to the graphene layer 40, the electrical resistance value of the graphene layer 40 also changes. This is called the optical bias effect.
• the current I can be made zero by adjusting the voltage V to perform reverse bias operation.
• the electromagnetic wave detector according to this embodiment is capable of off operation. At this time, the current I flows through the Schottky junction between the graphene layer 40 and the substrate 10 only when light is irradiated, so the current I can be detected only when light is irradiated.
• electromagnetic waves may be detected by using two or more of the same electromagnetic wave detectors 100A.
• two or more of the same electromagnetic wave detectors 100A are prepared.
• One electromagnetic wave detector 100A is placed in a shielded space where electromagnetic waves are not irradiated, and the other electromagnetic wave detector 100A is placed in a space where the electromagnetic waves to be measured are irradiated.
• the difference between the current I or voltage V of the other electromagnetic wave detector 100A irradiated with electromagnetic waves and the current I or voltage V of the electromagnetic wave detector 100A placed in the shielded space is detected. In this way, electromagnetic waves may be detected.
• the range of the main detection wavelength of the electromagnetic wave detector 100A is determined according to the constituent material of the thermoelectric material layer 70.
• electromagnetic waves of the detection wavelength are incident on the thermoelectric material layer 70, carriers are generated in the thermoelectric material layer 70 by thermoelectric conversion.
• the generated carriers are extracted as photocurrent from the electrode 60 and the substrate 10.
• the carriers generated in the region directly under the insulating film 50 cause an electric field change in the graphene layer 40 through the insulating film 50.
• the resistance value of the thermoelectric material layer 70 changes, a change occurs in the bias voltage applied to the graphene layer 40, and the electrical resistance value of the graphene layer 40 changes. This is the optical bias effect described above.
• thermoelectric material layer 70 since the thermoelectric material layer 70 generates heat when irradiated with electromagnetic waves, the heat generated in the thermoelectric material layer 70 is transmitted to the diode composed of the graphene layer 40 and the substrate 10, changing the diode characteristics of the diode. This is the thermal gate effect described above.
• the combination of these resistance changes changes the resistance value of the graphene layer 40, the thermoelectric material layer 70, and the diode composed of the graphene layer 40 and the substrate 10, and this change can be detected as an electrical signal to operate the electromagnetic wave detector 100A.
• the graphene that constitutes the graphene layer 40 has high mobility, and a large displacement current can be obtained for a small change in resistance. Therefore, the current extracted from the electrode 60 via the graphene layer 40 due to the thermoelectric conversion of the thermoelectric material layer 70 is greatly amplified by the optical gate effect, optical bias effect, and thermal gate effect. Therefore, the electromagnetic wave detector 100A can achieve high sensitivity that significantly exceeds the efficiency of the thermoelectric conversion of the thermoelectric material layer 70.
• the electromagnetic wave detector 100A there is a Schottky junction between the substrate 10 (semiconductor layer 11) and the graphene layer 40. That is, in the electromagnetic wave detector 100A, a diode exists between the substrate 10 and the graphene layer 40. Therefore, in the electromagnetic wave detector 100A, a current flows during quasi-bias, but no current flows during reverse bias. That is, the electromagnetic wave detector 100A is capable of off operation.
• thermoelectric material layer 70 generates heat when irradiated with electromagnetic waves.
• the heat generated in the thermoelectric material layer 70 is transferred to the diode, causing a change in the diode characteristics of the diode.
• the current flowing through the electromagnetic wave detector 100A changes (thermal gate effect).
• the heat generated by the thermoelectric material layer 70 when irradiated with electromagnetic waves has low dependency on the wavelength of the incident electromagnetic waves. Therefore, the electromagnetic wave detector 100A can improve the detection accuracy of electromagnetic waves.
• thermoelectric material layer 70 carriers are generated in the thermoelectric material layer 70 by irradiation with electromagnetic waves. Since the graphene layer 40 is disposed opposite the thermoelectric material layer 70 with the insulating film 50 interposed therebetween, the Fermi level in the graphene layer 40 changes due to the potential difference between the thermoelectric material layer 70 and the graphene layer 40 caused by the generation of carriers, and the electrical resistance value of the graphene layer 40 changes (optical gate effect). Furthermore, the electrical resistance value of the graphene layer 40 also changes due to a change in the bias voltage applied to the graphene layer 40 caused by the generation of photocarriers (optical bias effect).
• the single-layer graphene constituting the graphene layer 40 is only one atom thick, the generation of carriers in the thermoelectric material layer 70 causes a large change in the Fermi level and electrical resistance value of the graphene layer 40.
• the single-layer graphene constituting the graphene layer 40 has a large electron mobility. Therefore, due to the optical gate effect and optical bias effect, the change in current accompanying the incidence of electromagnetic waves on the thermoelectric material layer 70 becomes extremely large. From this perspective, the electromagnetic wave detector 100A can improve the detection accuracy of electromagnetic waves.
• thermoelectric material layer 70 When the material constituting the thermoelectric material layer 70 is a layered material such as multi-layer graphene, the electrical resistance value in the thickness direction is larger than the cell resistance value in the in-plane direction.
• the thermoelectric material layer 70 In the electromagnetic wave detector 100A, the thermoelectric material layer 70 is in edge contact with the electrodes 60 and 30 (the side surfaces 70a and 70b are connected to the electrodes 60 and 30, respectively), so that the efficiency of extracting carriers generated by the electromagnetic waves entering the thermoelectric material layer 70 is improved.
• the band is linearly dispersed, so that the wavelength band of the electromagnetic waves that can be absorbed is wide.
• the absorption rate of the electromagnetic waves of multi-layer graphene increases according to the number of layers stacked.
• the detection sensitivity to the electromagnetic waves is further improved by using multi-layer graphene as the material constituting the thermoelectric material layer 70.
• the material constituting the thermoelectric material layer 70 is a thin layered material of about several layers or a bulk material, it is not necessarily necessary to form edge contacts.
• the constituent material of the substrate 10 is a semiconductor material, it is possible to form an external circuit, such as a readout circuit, connected to the electromagnetic wave detector 100A on the substrate 10.
• an external circuit such as a readout circuit
• FIG. 3 is a cross-sectional view of the electromagnetic wave detector 100A according to the first modification.
• FIG. 3 shows a cross section at a position corresponding to II-II in FIG. 1.
• the electromagnetic wave detector 100A may further include a buffer layer 12.
• the constituent material of the buffer layer 12 is an electrically insulating material.
• Specific examples of the constituent material of the buffer layer 12 include metal oxides such as alumina and hafnium oxide, oxides of semiconductor materials such as silicon oxide and silicon nitride, and boron nitride.
• the buffer layer 12 is formed by using an ALD method, a vacuum deposition method, a sputtering method, or the like.
• the buffer layer 12 may be formed by oxidizing or nitriding the surface 10a, or a natural oxide film present on the surface 10a may be used as the buffer layer 12.
• the buffer layer 12 is disposed on the surface 10a exposed from the opening of the insulating film 20, and one end of the graphene layer 40 is in contact with the surface 10a via the buffer layer 12.
• the buffer layer 12 has a thickness that allows a tunneling current to flow (for example, a thickness of 1 nm or more and 10 nm or less). Therefore, even with the buffer layer 12 interposed, the graphene layer 40 and the substrate 10 are electrically connected, and a Schottky junction exists between them.
• the buffer layer 12 is interposed between the graphene layer 40 and the substrate 10 as described above, the insulating performance between the graphene layer 40 and the substrate 10 is improved, making it possible to reduce dark current (reduce noise).
• FIG. 4 is a cross-sectional view of the electromagnetic wave detector 100A according to Modification 2.
• Fig. 5 is a cross-sectional view of the electromagnetic wave detector 100A according to Modification 3.
• Figs. 4 and 5 show a cross section at a position corresponding to II-II in Fig. 1.
• the graphene layer 40 has a side surface 40a in contact with the electrode 30 at the other end.
• the insulating film 50 has a side surface 50a in contact with the electrode 30.
• the position of side 40a, the position of side 50a, and the position of side 70b may be aligned with each other.
• the electrode 30 can be formed by embedding the electrode 30 after etching the ends of the graphene layer 40 and the thermoelectric material layer 70, which makes the manufacturing process easier.
• the number of times the electrodes are formed is reduced, which reduces process damage to the graphene layer 40 and the thermoelectric material layer 70.
• the side 70a and the side 70b may be inclined so that the distance between the side 70a and the side 70b increases as the side approaches the insulating film 50.
• the side 40a, the side 50a, and the side 70b may be inclined flat surfaces.
• the side of the electrode 30 in contact with the side 40a, the side 50a, and the side 70b may be inclined so that the upper end protrudes more than the lower end, and the side of the electrode 60 in contact with the side 70a may be inclined so that the upper end protrudes more than the lower end.
• the inclined flat surface is formed by performing etching in a state in which the graphene layer 40, the insulating film 50, and the thermoelectric material layer 70 are formed.
• the electrode 30 is formed by a vacuum deposition method or the like, and at this time, the inclined flat surface becomes the film formation surface, so that good contact can be ensured between the electrode 30 and the inclined flat surface even if the film is not formed in an inclined state.
• the side surface 70a is inclined, and the electrode 60 is formed using the side surface 70a as a deposition surface, so good contact between the side surface 70a and the electrode 60 can be ensured.
• FIG. 6 is a cross-sectional view of the electromagnetic wave detector 100A according to the fourth modification.
• FIG. 7 is a cross-sectional view of the electromagnetic wave detector 100A according to the fifth modification.
• FIGS. 6 and 7 show a cross section at a position corresponding to II-II in FIG. 1.
• the electromagnetic wave detector 100A may further include an electrode 80.
• the electrode 80 is disposed on the surface 10a.
• the electrode 80 has a surface 80a.
• the surface 80a is a surface facing the opposite side to the substrate 10.
• the surface 80a and the surface 20a may be flat surfaces.
• the material of the electrode 80 may be any material as long as it is a conductor.
• the material of the electrode 80 may include at least one of aluminum, gold, silver, copper, nickel, chromium, and palladium, for example.
• One end of the graphene layer 40 is disposed on the electrode 80 (surface 80a).
• the electrode 80 and the substrate 10 are Schottky junctioned. Therefore, in this case as well, there is a Schottky junction between the graphene layer 40 and the substrate 10. In this case, the contact resistance between the graphene layer 40 and the substrate 10 can be reduced compared to when there is no electrode 80. Also, in this case, the graphene layer 40 becomes flat, and therefore the carrier mobility in the graphene layer 40 is improved.
• the graphene layer 40 may face the substrate 10 with a gap 21 therebetween. That is, the insulating film 20 below the graphene layer 40 may be removed, for example, by etching. In this case, carriers flowing through the graphene layer 40 are not scattered by the underlying insulating film 20, and the mobility of carriers is improved, and the efficiency of carrier extraction is improved, thereby further improving the detection sensitivity for electromagnetic waves.
• Embodiment 2 An electromagnetic wave detector according to embodiment 2 will be described.
• the electromagnetic wave detector according to embodiment 2 is designated as electromagnetic wave detector 100B.
• differences from electromagnetic wave detector 100A will be mainly described, and overlapping descriptions will not be repeated.
• FIG. 8 is a cross-section of the electromagnetic wave detector 100B. Note that FIG. 8 shows a cross-section at a position corresponding to II-II in FIG. 1. As shown in FIG. 8, the electromagnetic wave detector 100B has a substrate 10, an insulating film 20, an electrode 30, a graphene layer 40, an insulating film 50, an electrode 60, and a thermoelectric material layer 70. In this respect, the configuration of the electromagnetic wave detector 100B is common to the configuration of the electromagnetic wave detector 100A.
• the electromagnetic wave detector 100B further includes an electrode 80.
• the semiconductor layer 11 is configured separately from the substrate 10.
• the semiconductor layer 11 is disposed on the insulating film 20.
• one end of the graphene layer 40 is disposed on the electrode 80 (surface 80a), and the other end of the graphene layer 40 is disposed on the semiconductor layer 11.
• the graphene layer 40 is Schottky-bonded to the semiconductor layer 11.
• the electrode 30 is disposed on the semiconductor layer 11 so as to protrude from the insulating film 50.
• the power supply 110 is connected between the electrode 60 and the electrode 80. In these respects, the configuration of the electromagnetic wave detector 100B differs from the configuration of the electromagnetic wave detector 100A.
• the Schottky junction between the semiconductor layer 11 and the graphene layer 40 is closer to the thermoelectric material layer 70 than in the electromagnetic wave detector 100A. Therefore, heat generated in the thermoelectric material layer 70 is easily transferred to the vicinity of the Schottky junction, and the thermal gate effect is easily generated, further improving the detection sensitivity to electromagnetic waves.
• the substrate 10 and the semiconductor layer 11 it is possible to use a substrate 10 made of any material.
• FIG. 9 is a cross-sectional view of the electromagnetic wave detector 100B according to the first modification.
• FIG. 10 is a cross-sectional view of the electromagnetic wave detector 100B according to the second modification.
• FIGS. 9 and 10 show a cross section at a position corresponding to II-II in FIG. 1.
• the electrode 80 is disposed on the insulating film 20.
• the semiconductor layer 11 is disposed on the electrode 30, and the electrode 30 is disposed on the insulating film 20.
• the thermoelectric material layer 70 is disposed on the insulating film 20 so that the side surface 70a and the side surface 70b are connected to the electrode 80 and the electrode 30, respectively.
• the graphene layer 40 is disposed on the insulating film 50 so as to be connected to the electrode 60 and the semiconductor layer 11. In this case, the graphene layer 40 is formed after the semiconductor layer 11 and the electrode 60 are formed, so that process damage to the graphene layer 40 can be reduced.
• Embodiment 3 An electromagnetic wave detector according to embodiment 3 will be described.
• the electromagnetic wave detector according to embodiment 3 is designated as electromagnetic wave detector 100C.
• differences from electromagnetic wave detector 100A will be mainly described, and overlapping descriptions will not be repeated.
• FIG. 11 is a cross-section of the electromagnetic wave detector 100C. Note that FIG. 11 shows a cross-section at a position corresponding to II-II in FIG. 1. As shown in FIG. 11, the electromagnetic wave detector 100C has a substrate 10, an insulating film 20, an electrode 30, a graphene layer 40, an insulating film 50, an electrode 60, and a thermoelectric material layer 70. In this respect, the configuration of the electromagnetic wave detector 100C is common to the configuration of the electromagnetic wave detector 100A.
• the substrate 10 has a protrusion 10c on the surface 10a.
• the top surface of the protrusion 10c and the surface 20a may be flat.
• one end of the graphene layer 40 is on the protrusion 10c (connected to the protrusion 10c), and the other end of the graphene layer 40 is connected to the electrode 30. More specifically, the side surface 40a is connected to the electrode 30.
• the insulating film 50 is a two-dimensional insulating film.
• the insulating film 50 is made of, for example, hexagonal boron nitride (h-BN).
• the thickness of the insulating film 50 may be such that a tunneling current flows between the graphene layer 40 and the thermoelectric material layer 70, or such that a tunneling current does not flow between the graphene layer 40 and the thermoelectric material layer 70.
• the positions of the side surface 40a, the side surface 50a, and the side surface 70b may be aligned with each other. In these respects, the configuration of the electromagnetic wave detector 100C differs from the configuration of the electromagnetic wave detector 100A.
• the insulating film 50 is a two-dimensional insulating film, and therefore the insulating film 50 and the graphene layer 40 are lattice-matched. This improves the mobility of carriers in the graphene layer 40.
• the insulating film 50 is a two-dimensional insulating film, it is possible to form the insulating film 50 thin, which further strengthens the optical gate effect and the thermal gate effect, and further improves the detection sensitivity to electromagnetic waves.
• the thickness of the two-dimensional insulating film constituting the insulating film 50 is such that a tunneling current flows, carriers generated in the thermoelectric material layer 70 are tunnel-injected into the graphene layer 40 via the insulating film 50, causing a change in the Fermi level of the graphene layer 40.
• the graphene layer 40 and the insulating film 50 can be transferred in a stacked state after the electrode 30 is formed, which reduces process damage and makes it easy to obtain edge contact between the graphene layer 40 and the electrode 30.
• Fig. 12 is a cross-sectional view of an electromagnetic wave detector 100C according to the first modification. Note that Fig. 12 shows a cross section at a position corresponding to II-II in Fig. 1. As shown in Fig. 12, the other end of the graphene layer 40 may be disposed on the electrode 30. Moreover, the thermoelectric material layer 70 is disposed on the insulating film 50 such that one end is disposed on the electrode 60 and the other end is disposed on the electrode 30.
• the graphene layer 40 and the insulating film 50 are transferred after the electrode 30 is formed, and then the electrode 60 is formed and the thermoelectric material layer 70 is transferred.
• the electrode 60 is formed, the graphene layer 40 is covered with the insulating film 50, and no process for forming the electrode is performed after the thermoelectric material layer 70 is transferred. Therefore, in this case, process damage to the graphene layer 40 and the thermoelectric material layer 70 can be reduced.
• Fig. 13 is a cross-sectional view of an electromagnetic wave detector 100C according to Modification 2. Note that Fig. 13 shows a cross section at a position corresponding to II-II in Fig. 1. As shown in Fig. 13, the electromagnetic wave detector 100C does not need to have the electrode 30. In this case, the thermoelectric material layer 70 is disposed on the insulating film 50 such that the other end of the thermoelectric material layer 70 is disposed on the other end of the graphene layer 40.
• the other end of the thermoelectric material layer 70 forms a Vendel-Waals heterojunction with the other end of the graphene layer 40, causing an optical switch effect in which the Fermi level of the graphene layer 40 is modulated, changing the barrier between the graphene layer 40 and the thermoelectric material layer 70, and obtaining a large current.
• the graphene layer 40 is covered with the insulating film 50 when the electrode 60 is formed, and no process for forming an electrode is performed after the thermoelectric material layer 70 is transferred, so that process damage to the graphene layer 40 and the thermoelectric material layer 70 can be reduced.
• FIG. 14 is a cross-sectional view of an electromagnetic wave detector 100C according to Modification 3.
• FIG. 14 shows a cross section at a position corresponding to II-II in FIG. 1.
• the electrode 60 may be disposed on the insulating film 20.
• the positions of the side surfaces 40a, 50a, and 70b may be aligned with each other, and the side surfaces 40a, 50a, and 70b may be in contact with the electrode 30.
• the side surface 70a may be in contact with the electrode 60.
• the stacked graphene layer 40, insulating film 50, and thermoelectric material layer 70 are transferred collectively. Therefore, process damage due to the transfer process of each layer can be reduced.
• FIG. 15 is a cross-sectional view of an electromagnetic wave detector 100C according to the fourth modification.
• FIG. 15 shows a cross section at a position corresponding to II-II in FIG. 1.
• the electromagnetic wave detector 100C may have an insulating film 90 and an insulating film 91.
• the insulating film 90 and the insulating film 91 are two-dimensional insulating films.
• the constituent material of the insulating film 90 and the constituent material of the insulating film 91 are, for example, hexagonal boron nitride.
• the insulating film 90 is interposed between the graphene layer 40 and the insulating film 20.
• the insulating film 91 covers the thermoelectric material layer 70.
• the electrode 60 may also be disposed on the insulating film 20.
• the insulating film 90 when the insulating film 90 is interposed between the graphene layer 40 and the insulating film 20 and the thermoelectric material layer 70 is covered with the insulating film 91, the graphene layer 40 and the thermoelectric material layer 70 are encapsulated in a two-dimensional insulating film, which makes it possible to reduce the effects of moisture and oxygen in the air, and residues and impurities in the process. Also, in this case, after the electrodes 30 and 60 are formed, the laminated insulating film 90, graphene layer 40, insulating film 50, thermoelectric material layer 70, and insulating film 91 are transferred all at once, so there is no need to perform a process of forming electrodes after this transfer, and process damage can be reduced.
• the insulating film 50 is a two-dimensional insulating film has been described, but the insulating film 50 may be an insulating film other than a two-dimensional insulating film.
• the protrusion 10c is formed on the substrate 10 has been described, but the protrusion 10c may not be formed on the substrate 10.
• the graphene layer 40 is electrically connected to the substrate 10 by an appropriate method.
• Embodiment 4 An electromagnetic wave detector according to embodiment 4 will be described.
• the electromagnetic wave detector according to embodiment 4 is assumed to be electromagnetic wave detector 100D.
• differences from electromagnetic wave detector 100A and electromagnetic wave detector 100B will be mainly described, and overlapping descriptions will not be repeated.
• FIG. 16 is a cross-sectional view of the electromagnetic wave detector 100D.
• FIG. 16 shows a cross-section at the same position as II-II in FIG. 1.
• FIG. 17 is a cross-sectional view of the laminate 120A.
• FIG. 18 is a cross-sectional view of the laminate 120B. As shown in FIG. 16 to FIG. 18, the electromagnetic wave detector 100D has a laminate 120A and a laminate 120B.
• the laminate 120A has a substrate 10 (semiconductor layer 11), an insulating film 20, an electrode 30, a graphene layer 40, and an insulating film 50. That is, the configuration of the laminate 120A is similar to that of the electromagnetic wave detector 100A, except that it does not have the electrode 60 and does not have the thermoelectric material layer 70.
• the laminate 120B has a substrate 10, an insulating film 20, an electrode 30, an insulating film 50, a thermoelectric material layer 70, and an electrode 80. In the laminate 120B, the electrode 80 is disposed on the substrate 10. That is, the configuration of the laminate 120B is similar to that of the electromagnetic wave detector 100B (see FIG. 9) according to the first modified example, except that it does not have the electrode 60, does not have the graphene layer 40, and the electrode 80 is disposed on the substrate 10.
• the electromagnetic wave detector 100D is formed by hybrid bonding of the laminate 120A and the laminate 120B. That is, in the electromagnetic wave detector 100D, the electrodes 30 of the laminate 120A and the electrodes 30 of the laminate 120B face each other, and the graphene layer 40 of the laminate 120A and the thermoelectric material layer 70 of the laminate 120B are stacked so as to face each other with the insulating film 50 of the laminate 120A and the insulating film 50 of the laminate 120B interposed therebetween.
• the bond between the electrode 30 of the laminate 120A and the electrode 30 of the laminate 120B is preferably a bond between the same type of metal material.
• the electrode 30 of the laminate 120A and the electrode 30 of the laminate 120B are made of copper, and the bond between the electrode 30 of the laminate 120A and the electrode 30 of the laminate 120B is a Cu-Cu bond.
• the power source 110 is connected to the substrate 10 (semiconductor layer 11) of the laminate 120A and the electrode 80 of the laminate 120B, thereby reading out the signal.
• Fig. 19 is a cross-sectional view of an electromagnetic wave detector 100D according to Modification 1.
• Fig. 20 is a cross-sectional view of an electromagnetic wave detector 100D according to Modification 2.
• the base material 10 of the stack 120B may be made thinner than the base material 10 of the stack 120A, for example, by being ground.
• the base material 10 of the stack 120B may be removed, for example, by being ground. Note that the base material 10 of the stack 120B is ground after hybrid bonding between the stack 120A and the stack 120B, for example.
• FIG. 21 is a cross-sectional view of an electromagnetic wave detector 100D according to Modification 3.
• FIG. 22 is a cross-sectional view of a laminate 120A in the electromagnetic wave detector 100D according to Modification 3.
• FIG. 23 is a cross-sectional view of a laminate 120B in the electromagnetic wave detector 100D according to Modification 3.
• the graphene layer 40 may be in edge contact with the electrode 30, and in the laminate 120B, the thermoelectric material layer 70 may be in edge contact with the electrode 30.
• the graphene layer 40 thermoelectric material layer 70
• a protective film is formed on the graphene layer 40 (thermoelectric material layer 70).
• the graphene layer 40 (thermoelectric material layer 70) is etched using the protective film as a mask to form an opening.
• an electrode 30 is formed in the opening, and edge contact between the graphene layer 40 (thermoelectric material layer 70) and the electrode 30 is achieved.
• the laminate 120A has the graphene layer 40, and the laminate 120B has the thermoelectric material layer 70, so that the graphene layer 40 and the thermoelectric material layer 70 can be formed on separate substrates 10. This eliminates the need to sequentially transfer and form these layers onto the same substrate 10, and it is possible to prevent damage to layers that have already been formed when forming the layers that will be formed later. In other words, the electromagnetic wave detector 100D can reduce the heat resistance temperature of the process and damage to layers that have already been formed.
• the substrate 10 of the laminate 120B When the substrate 10 of the laminate 120B is thinned or removed by grinding, it is possible to prevent the substrate 10 of the laminate 120B from interfering with the incidence of electromagnetic waves on the thermoelectric material layer 70. Furthermore, when the graphene layer 40 and the thermoelectric material layer 70 are in edge contact with the electrode 30, the contact resistance between the electrode 30 and the graphene layer 40 and the thermoelectric material layer 70 is reduced, improving the current extraction efficiency. Furthermore, in this case, the bonding area of the electrode 30 is increased, improving the accuracy of the hybrid bonding.
• ⁇ Appendix 1> A graphene layer; A thermoelectric material layer; A semiconductor layer; the graphene layer, the thermoelectric material layer, and the semiconductor layer are electrically connected in series; a Schottky junction between the graphene layer and the semiconductor layer.
• thermoelectric material layer is a multilayer graphene layer.
• thermoelectric material layer and the graphene layer are disposed opposite each other with the first insulating film interposed therebetween.
• thermoelectric material layer is disposed on the first insulating film.
• ⁇ Appendix 5> Further comprising a first electrode, the first electrode is disposed on the second insulating film, The electromagnetic wave detector according to claim 4, wherein the second end and the thermoelectric material layer are connected with the first electrode interposed therebetween.
• thermoelectric material layer is disposed on the first insulating film.
• thermoelectric material layer is disposed on the first insulating film.
• thermoelectric material layer is disposed on the first insulating film and connected to the first electrode.
• thermoelectric material layer has a third end and a fourth end, and is disposed on the second insulating film such that the third end and the fourth end are connected to the third electrode and the first electrode, respectively;
• the semiconductor layer is disposed on the first electrode;
• the first insulating film covers the thermoelectric material layer; 4.
• ⁇ Appendix 17> Further comprising a first electrode; the first electrode is disposed on the second insulating film; 17. The electromagnetic wave detector of claim 16, wherein the second end is connected to the thermoelectric material layer via the first electrode.
• the graphene layer has a first side at the second end; the thermoelectric material layer has a third end and a fourth end; the thermoelectric material layer has a second side at the fourth end; 18.
• the first insulating film has a fourth side surface in contact with the first electrode; 19.
• thermoelectric material layer has a third side at the third end; 19.

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