Light detecting element, light sensor unit, and receiving device

Abstract

The present application provides a novel light detecting element, a light sensor unit, and a receiving device. The present light detecting element has: a superlens having a plurality of nanostructures arranged two-dimensionally; a magnetic element having a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched by the first ferromagnetic layer and the second ferromagnetic layer, and light passing through the superlens is irradiated to the magnetic element.

Description

Technical Field

[0001] This invention relates to optical detection elements, optical sensor units, and receiving devices. Background Technology

[0002] Photoelectric conversion elements are used in a variety of applications.

[0003] For example, Patent Document 1 describes a receiving device that uses a photodiode to receive optical signals. The photodiode is, for example, a pn-junction diode using a semiconductor pn-junction. Furthermore, for example, Patent Document 2 describes a light sensor using a semiconductor pn-junction and an image sensor using that light sensor.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2001-292107

[0007] Patent Document 2: US Patent No. 9,842,874 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] Although optical sensors using PN junctions with semiconductors are widely used, new breakthroughs are required for further development.

[0010] The present invention was made in view of the above-mentioned problems, and its purpose is to provide a novel optical detection element, optical sensor unit and receiving device.

[0011] Technical solutions for solving the problem

[0012] To address the aforementioned issues, the following technical solution is provided.

[0013] (1) A first method provides a photodetector having: a superlens having a plurality of nanostructures arranged in two dimensions; a magnetic element having a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, wherein light passing through the superlens is irradiated onto the magnetic element.

[0014] (2) In the optical detection element described above, when viewed from above the arrangement surface of the plurality of nanostructures, the superlens has a first region, and the top view area of ​​each of the plurality of nanostructures contained in the first region decreases from the center of the first region toward the outside.

[0015] (3) In the optical detection element described above, when viewed from above the arrangement surface of the plurality of nanostructures, the superlens also has an annular region outside the first region, and the top view area of ​​each of the plurality of nanostructures enclosing the annular region decreases from the inner peripheral side of the annular region toward the outer peripheral side.

[0016] (4) In the optical detection element described above, when viewed from above the arrangement surface of the plurality of nanostructures, each of the plurality of nanostructures has a long side direction and a short side direction in its top view shape, and the configuration angle of the top view shape of at least one of the plurality of nanostructures is different from the configuration angle of the top view shape of the other nanostructures.

[0017] (5) In the light detection element described above, the magnetic element may also be positioned at the focal point of the light converged by the superlens.

[0018] (6) In the optical detection element described above, the light may be light in a specific wavelength region within the wavelength region of 380 nm or more and less than 800 nm.

[0019] (7) In the optical detection element described above, the light may be light in a specific wavelength region in the wavelength region of 800 nm or more and 1 mm or less.

[0020] (8) In the optical detection element described above, the light may be light in a specific wavelength region in the wavelength region of 200 nm or more and less than 380 nm.

[0021] (9) A second approach provides a light sensor unit having multiple light detection elements, wherein the multiple light detection elements are light detection elements of the above approach.

[0022] (10) In the optical sensor unit of the above manner, the plurality of optical detection elements may also include at least a first optical detection element and a second optical detection element. The first optical detection element is provided with the magnetic element at the focal point of light in a first wavelength region converged by the superlens, and the second optical detection element is provided with the magnetic element at the focal point of light in a second wavelength region different from the first wavelength region converged by the superlens.

[0023] (11) In the optical sensor unit of the above manner, the first wavelength region may be a specific wavelength region in the wavelength region of 380nm or more and less than 800nm, and the second wavelength region may be a specific wavelength region in the wavelength region of 800nm ​​or more and less than 1mm.

[0024] (12) In the optical sensor unit of the above manner, the plurality of optical detection elements may also have a third optical detection element, wherein the magnetic element is disposed at the focal point of light in a third wavelength region that is different from the first wavelength region and the second wavelength region converged by the superlens, and the third wavelength region is a specific wavelength region in the wavelength region of 200 nm or more and less than 380 nm.

[0025] (13) In the optical sensor unit of the above-described manner, the plurality of optical detection elements may also be arranged in one dimension.

[0026] (14) In the optical sensor unit of the above-described manner, the plurality of optical detection elements may also be arranged in a two-dimensional arrangement.

[0027] (15) In the optical sensor unit of the above manner, at least one of the optical detection elements constituting a pixel among the plurality of optical detection elements may have a different structure of the nanostructure of the superlens compared with the other optical detection elements constituting the pixel.

[0028] (16) In the optical sensor unit of the above manner, at least one of the optical detection elements constituting a pixel may have a different distance between the superlens and the magnetic element compared to the other optical detection elements constituting the pixel.

[0029] (17) A third approach provides a receiving device having a light detection element as described above.

[0030] Invention Effects

[0031] The optical detection element, optical sensor unit, and receiving device described above operate based on a novel principle. Attached Figure Description

[0032] Figure 1 This is a cross-sectional view of the light detection element according to the first embodiment.

[0033] Figure 2 This is a top view of the first example of a superlens.

[0034] Figure 3 This is a schematic diagram of one unit that constitutes the superlens in the first example.

[0035] Figure 4 This is a top view of the superlens in the second example.

[0036] Figure 5 This is a schematic diagram of one unit that constitutes the superlens in the second example.

[0037] Figure 6This is a schematic diagram used to explain the operation of the light detection element in the first embodiment.

[0038] Figure 7 This is a diagram used to explain the first mechanism of the first operating example of the light detection element in the first embodiment.

[0039] Figure 8 This is a diagram illustrating the second mechanism of the first operating example of the light detection element in the first embodiment.

[0040] Figure 9 This is a diagram illustrating the first mechanism of a second operating example of the light detection element in the first embodiment.

[0041] Figure 10 This is a diagram illustrating the second mechanism of a second operating example of the light detection element in the first embodiment.

[0042] Figure 11 This is a diagram illustrating another example of the second operation of the light detection element in the first embodiment.

[0043] Figure 12 This is a diagram illustrating another example of the second operation of the light detection element in the first embodiment.

[0044] Figure 13 This is a conceptual diagram of the optical sensor device in the first application example.

[0045] Figure 14 This is a diagram illustrating an example of the specific structure of the optical sensor unit in the first application example.

[0046] Figure 15 This is a conceptual diagram of the cross-section of the optical sensor device in the first application example.

[0047] Figure 16 This is a diagram illustrating an example of the specific structure of the optical sensor unit in the first modified example.

[0048] Figure 17 This is a conceptual diagram of the cross-section of the optical sensor device in the second variation.

[0049] Figure 18 This is a conceptual diagram of the transceiver system in the second application example.

[0050] Figure 19 This is a block diagram of the transceiver device in the second application example.

[0051] Figure 20 This is a magnified schematic diagram of the vicinity of the optical detection element in the transceiver device of the second application example.

[0052] Figure 21 This is a conceptual diagram of another example of a communication system.

[0053] Figure 22 This is a conceptual diagram of another example of a communication system. Detailed Implementation

[0054] Hereinafter, embodiments will be described in detail with reference to appropriate figures. In the accompanying drawings used in the following description, for ease of understanding, some features are sometimes shown enlarged for convenience, and the dimensions and proportions of each component may differ from the actual dimensions. The materials, dimensions, etc., illustrated in the following description are examples, and the present invention is not limited thereto; appropriate modifications and implementations can be made within the scope of achieving the effects of the present invention.

[0055] Directions are defined as follows: The stacking direction of the magnetic element 10 is defined as the z-direction; a direction within a plane orthogonal to the z-direction is defined as the x-direction; and a direction orthogonal to both the x- and z-directions is defined as the y-direction. Hereinafter, the +z direction may be expressed as "up" and the -z direction as "down." The +z direction is from the magnetic element 10 toward the superlens 20. Up and down are not necessarily aligned with the direction of applied gravity.

[0056] First Implementation Method

[0057] Figure 1 This is a cross-sectional view of the light detection element 100 according to the first embodiment. Figure 1 In the diagram, arrows indicate the direction of magnetization in the initial state of a ferromagnetic material.

[0058] The photodetector 100 includes a magnetic element 10 and a superlens 20. Light that has passed through the superlens 20 is shone onto the magnetic element 10. The magnetic element 10 detects the light that has been shone onto it. The magnetic element 10 converts the light into an electrical signal. The superlens 20 converges the light toward the magnetic element 10. The magnetic element 10 is, for example, positioned at the focal point of the light converged by the superlens 20. An insulating layer 91 is, for example, between the magnetic element 10 and the superlens 20.

[0059] The light used in this specification is not limited to visible light, but also includes infrared light with wavelengths longer than visible light, or ultraviolet light with wavelengths shorter than visible light. Visible light has wavelengths of, for example, 380 nm or more and less than 800 nm. Infrared light has wavelengths of, for example, 800 nm or more and less than 1 mm. Ultraviolet light has wavelengths of, for example, 200 nm or more and less than 380 nm.

[0060] The magnetic element 10 has at least a first ferromagnetic layer 1, a second ferromagnetic layer 2, and a spacer layer 3. The spacer layer 3 is located between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. In addition, the magnetic element 10 may also have a buffer layer 4, a seed layer 5, a third ferromagnetic layer 6, a magnetic coupling layer 7, a vertical magnetization induction layer 8, a cover layer 9, and an insulating layer 90. The buffer layer 4, seed layer 5, third ferromagnetic layer 6, and magnetic coupling layer 7 are located between the second ferromagnetic layer 2 and the second electrode 12. The vertical magnetization induction layer 8 and the cover layer 9 are located between the first ferromagnetic layer 1 and the first electrode 11. The insulating layer 90 is located between the first electrode 11 and the second electrode 12, covering the periphery of the laminate 15.

[0061] The magnetic element 10 is, for example, an MTJ (Magnetic Tunnel Junction) element in which the spacer layer 3 is made of insulating material. When the magnetic element 10 is illuminated by external light, its resistance changes. The resistance of the magnetic element 10 in the z-direction (the resistance when current flows in the z-direction) varies according to the relative change in the magnetization state M1 of the first ferromagnetic layer 1 and the magnetization state M2 of the second ferromagnetic layer 2. Such an element is also called a magnetoresistive element.

[0062] The first ferromagnetic layer 1 is a light-detecting layer whose magnetization changes when illuminated by external light. The first ferromagnetic layer 1 is also referred to as a magnetization-free layer. A magnetization-free layer is a layer containing a magnetic material whose magnetization changes when energy is applied from a specified external source. This specified external energy can be, for example, externally illuminated light, a current flowing along the z-direction of the magnetic element 10, or an external magnetic field. The magnetization M1 of the first ferromagnetic layer 1 changes according to the intensity of the illuminated light.

[0063] The first ferromagnetic layer 1 comprises a ferromagnetic material. The first ferromagnetic layer 1 contains at least one of magnetic elements, such as Co, Fe, or Ni. The first ferromagnetic layer 1 may also contain elements such as B, Mg, Hf, and Gd along with the magnetic elements described above. The first ferromagnetic layer 1 may also be an alloy containing both magnetic and non-magnetic elements. The first ferromagnetic layer 1 may also be composed of multiple layers. For example, the first ferromagnetic layer 1 may be a CoFeB alloy, a stack of CoFeB alloy layers sandwiched by Fe layers, or a stack of CoFe alloy layers sandwiched by CoFe layers. Generally, "ferromagnetism" includes "ferrimagnetism." The first ferromagnetic layer 1 may also exhibit ferrimagnetism instead of ferrimagnetism. On the other hand, the first ferromagnetic layer 1 may also exhibit ferromagnetism instead of ferrimagnetism. For example, the CoFeB alloy exhibits ferromagnetism instead of ferrimagnetism.

[0064] The first ferromagnetic layer 1 can be an in-plane magnetized film with an easy magnetization axis in the in-plane direction (any direction in the xy plane), or a perpendicular magnetized film with an easy magnetization axis in the normal direction (z direction).

[0065] The thickness of the first ferromagnetic layer 1 is, for example, 1 nm or more and 5 nm or less. Preferably, the thickness of the first ferromagnetic layer 1 is 1 nm or more and 2 nm or less. When the first ferromagnetic layer 1 is a perpendicularly magnetized film, if the thickness of the first ferromagnetic layer 1 is thin, the effect of perpendicular magnetic anisotropy from the layers above and below the first ferromagnetic layer 1 is enhanced, and the perpendicular magnetic anisotropy of the first ferromagnetic layer 1 is increased. That is, if the perpendicular magnetic anisotropy of the first ferromagnetic layer 1 is high, the force required for magnetization M1 to return along the z-direction is enhanced. On the other hand, if the thickness of the first ferromagnetic layer 1 is thick, the effect of perpendicular magnetic anisotropy from the layers above and below the first ferromagnetic layer 1 is relatively weakened, and the perpendicular magnetic anisotropy of the first ferromagnetic layer 1 is weakened.

[0066] If the thickness of the first ferromagnetic layer 1 decreases, the volume of the ferromagnetic material decreases; if it increases, the volume of the ferromagnetic material increases. The ease with which the first ferromagnetic layer 1 is magnetized when external energy is applied is inversely proportional to the product (KuV) of the magnetic anisotropy (Ku) and volume (V) of the first ferromagnetic layer 1. That is, if the product of the magnetic anisotropy and volume of the first ferromagnetic layer 1 decreases, the reactivity to light increases. From this viewpoint, to improve the reactivity to light, it is preferable to reduce the volume of the first ferromagnetic layer 1 after appropriately designing the magnetic anisotropy of the first ferromagnetic layer 1.

[0067] When the thickness of the first ferromagnetic layer 1 is greater than 2 nm, an intercalation layer, for example, composed of Mo or W, can be disposed within the first ferromagnetic layer 1. That is, a stack of ferromagnetic layers, an intercalation layer, and another ferromagnetic layer sequentially stacked along the z-direction can also be used as the first ferromagnetic layer 1. The overall perpendicular magnetic anisotropy of the first ferromagnetic layer 1 is improved by the interfacial magnetic anisotropy at the interface between the intercalation layer and the ferromagnetic layer. The thickness of the intercalation layer is, for example, 0.1 nm to 1.0 nm.

[0068] The second ferromagnetic layer 2 is a magnetization-fixed layer. The magnetization-fixed layer is a layer composed of a magnetic material whose magnetization state is less likely to change compared to a magnetization-free layer when subjected to energy from a predetermined external source. For example, when energy from a predetermined external source is applied to the magnetization-fixed layer, the direction of magnetization is less likely to change compared to a magnetization-free layer. Additionally, for example, when energy from a predetermined external source is applied to the magnetization-fixed layer, the magnitude of magnetization is less likely to change compared to a magnetization-free layer. The coercivity of the second ferromagnetic layer 2 is, for example, greater than that of the first ferromagnetic layer 1. The second ferromagnetic layer 2, for example, has an easy magnetization axis in the same direction as the first ferromagnetic layer 1. The second ferromagnetic layer 2 can be an in-plane magnetization film or a perpendicular magnetization film.

[0069] The material constituting the second ferromagnetic layer 2 is, for example, the same as that of the first ferromagnetic layer 1. The second ferromagnetic layer 2 can also be, for example, a multilayer film in which Co with a thickness of 0.4 nm to 1.0 nm and Pt with a thickness of 0.4 nm to 1.0 nm are alternately stacked multiple times. Alternatively, the second ferromagnetic layer 2 can also be a laminate in which Co with a thickness of 0.4 nm to 1.0 nm, Mo with a thickness of 0.1 nm to 0.5 nm, a CoFeB alloy with a thickness of 0.3 nm to 1.0 nm, and Fe with a thickness of 0.3 nm to 1.0 nm are sequentially stacked.

[0070] The magnetization of the second ferromagnetic layer 2 can also be fixed, for example, by magnetic coupling with the third ferromagnetic layer 6 that holds the magnetic coupling layer 7. In this case, the layer combining the second ferromagnetic layer 2, the magnetic coupling layer 7, and the third ferromagnetic layer 6 is sometimes referred to as a magnetization-fixed layer. Details of the magnetic coupling layer 7 and the third ferromagnetic layer 6 will be described later.

[0071] Spacer layer 3 is disposed between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. Spacer layer 3 is made of a layer composed of a conductor, an insulator, or a semiconductor, or a layer containing current-carrying points composed of conductors within an insulator. Spacer layer 3 is, for example, a non-magnetic layer. The film thickness of spacer layer 3 can be adjusted according to the orientation direction of the magnetization of the first ferromagnetic layer 1 and the magnetization of the second ferromagnetic layer 2 in the initial state described later.

[0072] When the spacer layer 3 is made of an insulating material, materials containing aluminum oxide, magnesium oxide, titanium oxide, or silicon oxide can be used as the material for the spacer layer 3. Alternatively, these insulating materials can also contain elements such as Al, B, Si, and Mg, or magnetic elements such as Co, Fe, and Ni. By adjusting the thickness of the spacer layer 3, a high TMR effect is achieved between the first ferromagnetic layer 1 and the second ferromagnetic layer 2, thereby obtaining a high magnetoresistivity change rate. To efficiently utilize the TMR effect, the thickness of the spacer layer 3 can be set to approximately 0.5–5.0 nm, or approximately 1.0–2.5 nm.

[0073] When the spacer layer 3 is composed of a non-magnetic conductive material, conductive materials such as Cu, Ag, Au, or Ru can be used. In order to efficiently utilize the GMR effect, the film thickness of the spacer layer 3 can be set to about 0.5 to 5.0 nm, or it can be set to about 2.0 to 3.0 nm.

[0074] When the spacer layer 3 is made of a non-magnetic semiconductor material, materials such as zinc oxide, indium oxide, tin oxide, germanium oxide, gallium oxide, or ITO can be used. In this case, the film thickness of the spacer layer 3 can also be set to about 1.0 to 4.0 nm.

[0075] When the spacer layer 3 is a non-magnetic insulator containing a layer with current-carrying points made of conductors, it can also be configured as a non-magnetic insulator made of aluminum oxide or magnesium oxide containing current-carrying points made of non-magnetic conductors such as Cu, Au, or Al. Alternatively, the conductors can be made of magnetic elements such as Co, Fe, or Ni. In this case, the film thickness of the spacer layer 3 can be set to about 1.0 to 2.5 nm. The current-carrying points are, for example, columnar bodies with a diameter of 1 nm or more and 5 nm or less when viewed from a direction perpendicular to the film surface.

[0076] The third ferromagnetic layer 6 is magnetically coupled to the second ferromagnetic layer 2, for example. This magnetic coupling is, for example, antiferromagnetic coupling, generated through RKKY interactions. The direction of magnetization M2 in the second ferromagnetic layer 2 and the direction of magnetization M6 in the third ferromagnetic layer 6 are antiparallel. The material constituting the third ferromagnetic layer 6 is, for example, the same as that in the first ferromagnetic layer 1.

[0077] The magnetic coupling layer 7 is located between the second ferromagnetic layer 2 and the third ferromagnetic layer 6. The magnetic coupling layer 7 is, for example, Ru, Ir, etc.

[0078] Buffer layer 4 is a layer that mitigates lattice mismatch between different crystals. Buffer layer 4 is, for example, a metal containing at least one element selected from the group consisting of Ta, Ti, Zr, and Cr, or a nitride containing at least one element selected from the group consisting of Ta, Ti, Zr, and Cu. More specifically, buffer layer 4 is, for example, Ta (monomer), NiCr alloy, TaN (tantalum nitride), or CuN (copper nitride). The film thickness of buffer layer 4 is, for example, 1 nm or more and 5 nm or less. Buffer layer 4 is, for example, amorphous. Buffer layer 4 is, for example, located between seed layer 5 and second electrode 12, and is in contact with second electrode 12. Buffer layer 4 suppresses the influence of the crystal structure of second electrode 12 on the crystal structure of second ferromagnetic layer 2.

[0079] The seed layer 5 improves the crystallinity of the layers stacked on top of the seed layer 5. The seed layer 5 is, for example, located between the buffer layer 4 and the third ferromagnetic layer 6, and is situated on the buffer layer 4. The seed layer 5 is, for example, Pt, Ru, Zr, or NiFeCr. The film thickness of the seed layer 5 is, for example, 1 nm or more and 5 nm or less.

[0080] The capping layer 9 is located between the first ferromagnetic layer 1 and the first electrode 11. The capping layer 9 may also include a vertically magnetized induction layer 8 stacked on and in contact with the first ferromagnetic layer 1. The capping layer 9 prevents damage to the underlying layer during the manufacturing process and improves the crystallinity of the underlying layer during annealing. The film thickness of the capping layer 9 is, for example, less than 10 nm, to allow sufficient light to irradiate the first ferromagnetic layer 1.

[0081] The vertical magnetization induction layer 8 senses the vertical magnetic anisotropy of the first ferromagnetic layer 1. The vertical magnetization induction layer 8 is, for example, magnesium oxide, W, Ta, Mo, etc. When the vertical magnetization induction layer 8 is magnesium oxide, it is preferable that the magnesium oxide is oxygen-deficient to improve conductivity. The film thickness of the vertical magnetization induction layer 8 is, for example, 0.5 nm or more and 5.0 nm or less.

[0082] The insulating layer 90 is, for example, an oxide, nitride, or oxynitride of Si, Al, or Mg. The insulating layer 90 is, for example, silicon oxide (SiO2). x ), silicon nitride (SiN) x Silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al2O3), zirconium oxide (ZrO2) x )wait.

[0083] The first electrode 11 is disposed, for example, on the superlens 20 side of the magnetic element 10. Incident light irradiates the magnetic element 10 from the first electrode 11 side, irradiating at least the first ferromagnetic layer 1. The first electrode 11 is made of a conductive material. The first electrode 11 is, for example, a transparent electrode that is transmissive to light in the wavelength range of use. The first electrode 11 preferably transmits more than 80% of the light in the wavelength range of use. The first electrode 11 is, for example, an oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), or indium gallium zinc oxide (IGZO). The first electrode 11 may also be provided as having a structure of multiple columnar metals in the transparent electrode material of these oxides. It is not necessary to use the transparent electrode material described above as the first electrode 11; the irradiated light can also reach the first ferromagnetic layer 1 by using a metal material such as Au, Cu, or Al with a thin film thickness. When a metal is used as the material of the first electrode 11, the film thickness of the first electrode 11 is, for example, 3 to 10 nm. In addition, the first electrode 11 may also have an anti-reflective film on the irradiated surface of the irradiated light.

[0084] The second electrode 12 is made of a conductive material. The second electrode 12 is made of a metal such as Cu, Al, or Au. Ta or Ti may also be stacked on top of these metals. Alternatively, a Cu and Ta laminate, a Ta, Cu, and Ti laminate, or a Ta, Cu, and TaN laminate may also be used. TiN or TaN may also be used as the second electrode 12. The film thickness of the second electrode 12 is, for example, 200 nm to 800 nm.

[0085] The second electrode 12 can also be transmissive to light irradiated onto the magnetic element 10. The material of the second electrode 12 can be the same as that of the first electrode 11, such as transparent electrode materials made of oxides like indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and indium gallium zinc oxide (IGZO). When light is irradiated from the first electrode 11, light may reach the second electrode 12 depending on the intensity of the light. However, in this case, because the second electrode 12 is constructed using a transparent electrode material made of oxides, light reflection at the interface between the second electrode 12 and the layer adjacent to it can be suppressed compared to the case where the second electrode 12 is made of metal.

[0086] The superlens 20 has multiple nanostructures 21. These nanostructures 21 are formed, for example, on a substrate 22. The superlens 20 is a lens utilizing a metasurface. The superlens 20 controls the phase distribution of light, functioning as a lens. The metasurface functions as a metamaterial through its planar structure. Metamaterials are media with a negative refractive index, or are designed to have a refractive index (dielectric constant, permeability) not found in nature. Because the superlens 20 can reduce the focal distance, the photodetector 100 can be miniaturized. Furthermore, because the superlens 20 can reduce the size of the focal spot, high-energy light can be efficiently irradiated onto the magnetic element 10.

[0087] The superlens 20 includes, for example, a dielectric that generates surface plasmon excitation. Additionally, the superlens 20 transmits light in the operating frequency band. The nanostructure 21 is, for example, titanium oxide or gallium nitride. If the light incident on the photodetector 100 is infrared, the nanostructure 21 may also be amorphous silicon. The substrate 22 is, for example, silicon dioxide or aluminum oxide.

[0088] Multiple nanostructures 21 are arranged in a two-dimensional plane on the xy plane. The xy plane is an example of the arrangement plane of multiple nanostructures 21. Figure 2 This is a top view of the first example of the superlens 20.

[0089] Figure 3 This is a schematic diagram of a unit 23 that constitutes the superlens 20 in the first example. Figure 3 The image above is a top view from the z-axis. Figure 3 The image below is a three-dimensional view. Multiple units 23 are arranged in the same plane to form a superlens 20.

[0090] The nanostructure 21 is, for example, a cylinder with a diameter φ and a height H. In the superlens 20, these nanostructures 21 are periodically arranged in each period U. In multiple nanostructures 21, the diameter φ has multiple values. In multiple nanostructures 21, the height H may have only one value or multiple values. The diameter φ and the period U are below the wavelength of the light used. Figure 3In the example shown, the length of the base 22 in a unit 23 in the x direction is U, and the length in the y direction is also U.

[0091] like Figure 2 As shown, for example, when viewed from above in the z-direction, the superlens 20 has a first region A1 and an annular region A2. The first region A1 is, for example, circular. The annular region A2 is located outside the first region A1. The outer periphery of the annular region A2 and the outer periphery of the first region A1 are, for example, concentric circles. The first region A1 contains a plurality of nanostructures 21. The annular region A2 also contains a plurality of nanostructures 21. The superlens 20 may also lack the annular region A2.

[0092] The top-view area of ​​each of the plurality of nanostructures 21 enclosed within the first region A1 decreases, for example, from the center of the first region A1 toward the outside. For example, in the first region A1, the diameter φ of the nanostructure 21 decreases from the center toward the outside.

[0093] The top-view area of ​​each of the plurality of nanostructures 21 enclosed within the annular region A2 decreases, for example, from the inner periphery of the annular region A2 toward the outer periphery. For example, in the annular region A2, the diameter φ of the nanostructure 21 decreases from the inner periphery toward the outer periphery. The top-view area of ​​the nanostructures 21 arranged at the innermost periphery of the annular region A2 is, for example, larger than the top-view area of ​​the nanostructures 21 arranged at the outermost periphery of the first region A1.

[0094] The superlens 20 can control the phase distribution of light by adjusting the configuration of multiple nanostructures 21, the size of each nanostructure 21, and the period of the configuration of the multiple nanostructures 21.

[0095] For example, Table 1 shows the diameter of the superlens 20 set to 3 μm, the focal distance of the light focused by the superlens 20 set to 3 μm, and the dimensions of each nanostructure 21 and the periodicity of the arrangement of multiple nanostructures 21 when the superlens 20 is composed only of the first region A1. In this example, the nanostructures 21 are made of titanium oxide, and the insulating layer 91 is made of silicon dioxide. In Table 1, λ is the wavelength of the light focused by the superlens 20 to a focal distance of 3 μm, and φ... max For the diameter of the largest nanostructure 21, φ min H is the diameter of the smallest nanostructure 21, H is the height of the nanostructure 21, and U is the period between the nanostructures 21.

[0096] Table 1

[0097] λ(nm) 1550 1310 880 633 530 430 290 <![CDATA[φ max (nm)]]> 725 630 410 290 240 195 135 <![CDATA[φ min (nm)]]> 471 410 267 189 156 127 88 H(nm) 800 800 800 800 800 800 800 U(nm) 755 656 427 302 250 203 140

[0098] As shown in Table 1, by adjusting the size and period of the nanostructure 21, the focal distance of the superlens 20 can be made the same even if the wavelengths of the incident light are different.

[0099] Furthermore, the structure of the superlens 20 is not limited to... Figure 2 and Figure 3 The structure shown. For example, in Figure 2 The outer side of the annular region A2 of the superlens 20 shown may also have one or more annular regions. Figure 4 This is a top view of the second example, the superlens 20A. Figure 5 This is a schematic diagram of a unit 23A that constitutes the superlens 20A in the second example. Figure 5 The image above is a top view from the z-axis. Figure 5 The image below is a 3D view. Multiple units 23A are arranged in the same plane to form a superlens 20A.

[0100] Multiple nanostructures 21A are arranged in two dimensions on the xy plane. When viewed from above on the xy plane, at least one of the nanostructures 21A has a different orientation angle compared to the planar shapes of the other nanostructures 21A.

[0101] For each nanostructure 21A, for example, the top-view shape has a long side direction and a short side direction. Figure 5 The nanostructure 21A shown is a cuboid with length L along its long side, width W along its short side, and height H. Its top view shows it as a rectangle with length L along its long side and width W along its short side. Length L, width W, and period U are below the wavelength of the light used. Figure 5 In the example shown, the length of the substrate 22 in a unit 23A in the x-direction is U, and the length in the y-direction is also U. In the superlens 20A, the nanostructures 21A are periodically arranged in each period U. The long side direction of the nanostructures 21A is tilted relative to the reference axis (e.g., the x-direction) at a configuration angle θ. In multiple nanostructures 21A, the configuration angle θ can also have multiple values; for example, its distribution can also have the regularity of Panchanratonam Berry geometric phase.

[0102] For example, Table 2 shows the dimensions of each nanostructure 21A and the period of arrangement of multiple nanostructures 21A when the diameter of the superlens 20A is set to 3 μm, the focal distance of the light converged by the superlens 20A is set to 3 μm, and the distribution of the arrangement angle θ of the nanostructures 21A satisfies the regularity of the Panchanratonam-Berry geometric phase. In this example, the nanostructures 21A are made of titanium oxide, and the insulating layer 91 is made of silicon dioxide. In Table 2, λ is the wavelength of the light converged by the superlens 20A to a focal distance of 3 μm, W is the top-view width of the nanostructure 21A, L is the top-view length of the nanostructure 21A, H is the height of the nanostructure 21A, and U is the period between the nanostructures 21A.

[0103] Table 2

[0104] λ(nm) 1550 1310 880 633 530 430 290 W(nm) 145 140 115 95 80 45 40 L(nm) 555 510 455 380 265 165 135 H(nm) 600 600 600 600 600 600 600 U(nm) 605 565 505 430 315 215 185

[0105] As shown in Table 2, by adjusting the size and period of the nanostructure 21A, the focal distance of the superlens 20A can be made the same even if the wavelengths of the incident light are different.

[0106] The insulating layer 91 is located between the magnetic element 10 and the superlens 20. The material of the insulating layer 91 is not particularly limited as long as it allows light in the operating frequency band to pass through. For example, the same material as the insulating layer 90 can be used in the insulating layer 91. The insulating layer 91 and the insulating layer 90 can be the same material or different materials. Furthermore, the insulating layer 91 and the substrate 22 can be the same material or different materials.

[0107] The photodetector 100 is obtained by sequentially fabricating a second electrode 12, a magnetic element 10, a first electrode 11, an insulating layer 91, and a superlens 20.

[0108] The magnetic element 10 is fabricated through a layer stacking process, an annealing process, and a processing process. First, a buffer layer 4, a seed layer 5, a third ferromagnetic layer 6, a magnetic coupling layer 7, a second ferromagnetic layer 2, a spacer layer 3, a first ferromagnetic layer 1, a vertical magnetization induction layer 8, and a capping layer 9 are sequentially stacked on the second electrode 12. Each layer is formed, for example, by sputtering.

[0109] Next, the laminated film is annealed. The annealing temperature is, for example, 250°C or higher and 400°C or lower. Then, the laminated film is processed into a columnar laminate 15 by photolithography and etching. The laminate 15 can be a cylinder or a prism. For example, the shortest width of the laminate 15 when viewed from the z-direction is 10 nm or higher and 1000 nm or lower.

[0110] Next, an insulating layer 90 is formed to cover the sides of the laminate 15. The insulating layer 90 may also be laminated multiple times. Then, the upper surface of the capping layer 9 is exposed from the insulating layer 90 by chemical mechanical polishing, and the first electrode 11 is formed on the capping layer 9.

[0111] Next, an insulating layer 91 is deposited on the first electrode 11. A resist with a predetermined pattern is formed on the upper surface of the insulating layer 91, and dry etching is performed. Holes with a predetermined pattern are formed on the upper surface of the insulating layer 91 by dry etching. Then, a superlens 20 is formed by filling the holes with the material constituting the nanostructure 21. Through the above steps, a photodetector element 100 is obtained. When using the wavelength filter 40 described later, a dielectric multilayer film, such as that which serves as the wavelength filter 40, is deposited between the first electrode 11 and the insulating layer 91. In this way, in the fabrication of the photodetector element 100, the magnetic element 10 and the superlens 20 can be continuously formed by a vacuum film deposition process.

[0112] Next, the operation of the light detection element 100 in the first embodiment will be explained. Figure 6 This is a schematic diagram used to illustrate the operation of the light detection element 100. Figure 6 In the image, the insulating layer 91 between the magnetic element 10 and the superlens 20 is omitted.

[0113] The light L incident on the photodetector 100 is converged by the superlens 20. For example... Figure 6 As shown, the light L incident on the superlens 20 can also be light that has passed through the polarization filter 30. The photodetector 100 can also have a polarization filter 30 on the side of the superlens 20 opposite to the magnetic element 10. In use... Figure 4 In the case of the superlens 20A shown, polarization filter 30 is preferably used. Even when using Figure 4 In the case of the superlens 20A shown, if the light incident on the light detection element 100 is polarized light such as laser light, the polarization filter 30 may not be necessary.

[0114] The magnetic element 10 is positioned at the focal point of the light L in the operating frequency band converged by the superlens 20. The focal point of the light L in the operating frequency band preferably overlaps with, for example, the first ferromagnetic layer 1. For example, when using visible light, the magnetic element 10 is positioned at the focal point of light in a specific wavelength region within the wavelength region of 380 nm to less than 800 nm. Similarly, when using infrared light, the magnetic element 10 is positioned at the focal point of light in a specific wavelength region within the wavelength region of 800 nm to less than 1000 nm. Furthermore, when using ultraviolet light, the magnetic element 10 is positioned at the focal point of light in a specific wavelength region within the wavelength region of 200 nm to less than 380 nm.

[0115] Alternatively, the light L irradiated onto the magnetic element 10 can also be light that has passed through the wavelength filter 40. The photodetector 100 may also have a wavelength filter 40. The wavelength filter 40 may be disposed, for example, between the magnetic element 10 and the superlens 20, or on the side of the superlens 20 opposite to the magnetic element 10. Moreover, the light L irradiated onto the magnetic element 10 has passed through the superlens 20.

[0116] The output voltage from the magnetic element 10 varies according to the intensity of the light L incident on the first ferromagnetic layer 1. The variation in the output voltage from the magnetic element 10 is influenced by the change in resistance along the stacking direction of the first ferromagnetic layer 1, the second ferromagnetic layer 2, and the spacer layer 3. In the first example, the case where the intensity of the light incident on the first ferromagnetic layer 1 is either a first intensity or a second intensity will be described. The intensity of the second intensity light is greater than the intensity of the first intensity light. The first intensity could also be the case where the intensity of the light incident on the first ferromagnetic layer 1 is zero.

[0117] Figure 7 and Figure 8 This is a diagram used to illustrate a first example of the operation of the magnetic element 10. Figure 7 This diagram is used to illustrate the first mechanism of the first action example. Figure 8 This diagram illustrates the second mechanism of the first action example. Figure 7 and Figure 8 In the illustration, only the first ferromagnetic layer 1, the second ferromagnetic layer 2, and the spacer layer 3 of the magnetic element 10 are shown. Figure 7 and Figure 8 In the chart above, the vertical axis represents the intensity of light irradiating the first ferromagnetic layer 1, and the horizontal axis represents time. Figure 7 and Figure 8 In the chart below, the vertical axis represents the resistance value of the magnetic element 10 in the z-direction, and the horizontal axis represents time.

[0118] First, in the state where light of a first intensity is irradiated onto the first ferromagnetic layer 1 (hereinafter referred to as the initial state), the magnetization M1 of the first ferromagnetic layer 1 and the magnetization M2 of the second ferromagnetic layer 2 are parallel. The resistance value in the z-direction of the magnetic element 10 represents the first resistance value R1, and the magnitude of the output voltage from the magnetic element 10 represents the first value. A voltage is generated across the magnetic element 10 in the z-direction by flowing an induced current Is along the z-direction, and the resistance value in the z-direction of the magnetic element 10 is calculated using Ohm's law based on this voltage value. The output voltage from the magnetic element 10 is generated between the first electrode 11 and the second electrode 12. Figure 7In the example shown, an induced current Is flows from the first ferromagnetic layer 1 toward the second ferromagnetic layer 2. By flowing the induced current Is in this direction, a spin-transfer torque in the same direction as the magnetization M2 of the second ferromagnetic layer 2 acts on the magnetization M1 of the first ferromagnetic layer 1. Initially, magnetization M1 and magnetization M2 are parallel. Furthermore, by flowing the induced current Is in this direction, it is possible to prevent the magnetization M1 of the first ferromagnetic layer 1 from reversing during operation.

[0119] Next, the intensity of the light irradiating the first ferromagnetic layer 1 changes from a first intensity to a second intensity. The second intensity is greater than the first intensity, and the magnetization M1 of the first ferromagnetic layer 1 changes from its initial state. The state of magnetization M1 of the first ferromagnetic layer 1 when no light is irradiated is different from the state of magnetization M1 of the first ferromagnetic layer 1 when light of the second intensity is irradiated. The state of magnetization M1 refers to, for example, its tilt angle or magnitude relative to the z-direction.

[0120] For example, such as Figure 7 As shown, if the intensity of light irradiating the first ferromagnetic layer 1 changes from a first intensity to a second intensity, the magnetization M1 tilts relative to the z-direction. Additionally, for example, as... Figure 8 As shown, if the intensity of the light irradiating the first ferromagnetic layer 1 changes from a first intensity to a second intensity, the magnitude of the magnetization M1 decreases. For example, when the magnetization M1 of the first ferromagnetic layer 1 is tilted relative to the z-direction according to the intensity of the light irradiation, its tilt angle is greater than 0° and less than 90°.

[0121] If the magnetization M1 of the first ferromagnetic layer 1 changes from its initial state, the resistance value in the z-direction of the magnetic element 10 represents the second resistance value R2, and the magnitude of the output voltage from the magnetic element 10 represents the second value. The second resistance value R2 is greater than the first resistance value R1, and the second value of the output voltage is greater than the first value. The second resistance value R2 lies between the resistance value when magnetizations M1 and M2 are parallel (the first resistance value R1) and the resistance value when magnetizations M1 and M2 are antiparallel.

[0122] exist Figure 7 In the illustrated case, a spin-transfer torque in the same direction as the magnetization M2 of the second ferromagnetic layer 2 acts on the magnetization M1 of the first ferromagnetic layer 1. Therefore, if magnetization M1 is to return to a state parallel to magnetization M2, and the intensity of light irradiated onto the first ferromagnetic layer 1 changes from a second intensity to a first intensity, the magnetic element 10 returns to its initial state. Figure 8In the scenario shown, if the intensity of the light irradiating the first ferromagnetic layer 1 returns to the first intensity, the magnetization M1 of the first ferromagnetic layer 1 is restored, and the magnetic element 10 returns to its initial state. In any case, the resistance value in the z-direction of the magnetic element 10 returns to the first resistance value R1. That is, when the intensity of the light irradiating the first ferromagnetic layer 1 changes from the second intensity to the first intensity, the resistance value in the z-direction of the magnetic element 10 changes from the second resistance value R2 to the first resistance value R1, and the magnitude of the output voltage from the magnetic element 10 changes from the second value to the first value.

[0123] The output voltage from the magnetic element 10 can change in response to changes in the intensity of light irradiating the first ferromagnetic layer 1, converting changes in the intensity of the irradiated light into changes in the output voltage from the magnetic element 10. That is, the magnetic element 10 can replace light with an electrical signal. For example, a first signal (e.g., "1") is treated when the output voltage from the magnetic element 10 is above a threshold, and a second signal (e.g., "0") is treated when the output voltage is below the threshold.

[0124] Here, the example is given where magnetization M1 and magnetization M2 are parallel in the initial state. However, magnetization M1 and magnetization M2 can also be antiparallel in the initial state. In this case, the more the state of magnetization M1 changes (e.g., the greater the change in the angle of magnetization M1 from the initial state), the smaller the resistance value in the z-direction of the magnetic element 10. When the initial state is set as antiparallel magnetization M1 and magnetization M2, the induced current Is preferably flows from the second ferromagnetic layer 2 toward the first ferromagnetic layer 1. By the induced current Is flowing in this direction, a spin-transfer torque in the opposite direction to the magnetization M2 of the second ferromagnetic layer 2 acts on the magnetization M1 of the first ferromagnetic layer 1. In the initial state, magnetization M1 and magnetization M2 are antiparallel.

[0125] In the first example, the case where the light irradiated onto the first ferromagnetic layer 1 has two phases, namely a first intensity and a second intensity, was explained. However, in the second example, the case where the intensity of the light irradiated onto the first ferromagnetic layer 1 changes in multiple phases or is simulated is explained.

[0126] Figure 9 and Figure 10 This is a diagram used to illustrate a second operating example of the magnetic element 10 in the first embodiment. Figure 9 This diagram is used to illustrate the first mechanism of the second action example. Figure 10 This diagram illustrates the second mechanism used to explain the second action example. Figure 9 and Figure 10 In the illustration, only the first ferromagnetic layer 1, the second ferromagnetic layer 2, and the spacer layer 3 of the magnetic element 10 are shown. Figure 9 and Figure 10In the chart above, the vertical axis represents the intensity of light illuminating the first ferromagnetic layer 1, and the horizontal axis represents time. Figure 9 and Figure 10 In the chart below, the vertical axis represents the resistance value of the magnetic element 10 in the z-direction, and the horizontal axis represents time.

[0127] exist Figure 9 In the case where the intensity of the light irradiating the first ferromagnetic layer 1 is high, the magnetization M1 of the first ferromagnetic layer 1 tilts from its initial state due to the energy from the outside based on the light irradiation. The angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 in the state without light irradiation and the angle between the direction of the magnetization M1 in the state with light irradiation are both greater than 0° and less than 90°.

[0128] If the magnetization M1 of the first ferromagnetic layer 1 tilts from its initial state, the resistance value in the z-direction of the magnetic element 10 changes. Furthermore, the output voltage from the magnetic element 10 changes. For example, depending on the tilt of the magnetization M1 of the first ferromagnetic layer 1, the resistance value in the z-direction of the magnetic element 10 becomes a second resistance value R2, a third resistance value R3, and a fourth resistance value R4, and the output voltage from the magnetic element 10 becomes a second value, a third value, and a fourth value. The resistance values ​​increase in the order of first resistance value R1, second resistance value R2, third resistance value R3, and fourth resistance value R4. The output voltage from the magnetic element 10 increases in the order of first value, second value, third value, and fourth value.

[0129] Regarding the magnetic element 10, when the intensity of light irradiating the first ferromagnetic layer 1 changes, the output voltage (resistance value in the z-direction of the magnetic element 10) from the magnetic element 10 changes. For example, if the first value (first resistance value R1) is defined as "0", the second value (second resistance value R2) as "1", the third value (third resistance value R3) as "2", and the fourth value (fourth resistance value R4) as "3", then information from four values ​​can be read from the magnetic element 10. Here, as an example, the case of reading four values ​​is shown, but the number of values ​​read can be freely designed by designing the threshold of the output voltage (resistance value of the magnetic element 10) from the magnetic element 10. Alternatively, the analog value of the output of the magnetic element 10 can also be used as is.

[0130] in addition, Figure 10The same applies to the first ferromagnetic layer 1. If the intensity of the light irradiating the first ferromagnetic layer 1 increases, the magnetization M1 of the first ferromagnetic layer 1 decreases from its initial state due to the external energy derived from the light irradiation. If the magnetization M1 of the first ferromagnetic layer 1 decreases from its initial state, the resistance value in the z-direction of the magnetic element 10 changes. Furthermore, the output voltage from the magnetic element 10 changes. For example, depending on the magnitude of the magnetization M1 of the first ferromagnetic layer 1, the resistance value in the z-direction of the magnetic element 10 becomes a second resistance value R2, a third resistance value R3, and a fourth resistance value R4, and the output voltage from the magnetic element 10 becomes a second, a third, and a fourth value, respectively. Therefore, with… Figure 9 Similarly, the differences in these output voltages (resistance values) can be read from the photodetector 100 as multi-valued or analog data.

[0131] In addition, the second action example is the same as the first action example. If the intensity of the light irradiated onto the first ferromagnetic layer 1 returns to the first intensity, the magnetization M1 state of the first ferromagnetic layer 1 is restored, and the magnetic element 10 returns to the initial state.

[0132] Here, the case where magnetization M1 and magnetization M2 are parallel in the initial state is explained as an example, but in the second example, magnetization M1 and magnetization M2 can also be antiparallel in the initial state.

[0133] Furthermore, in the first and second examples of operation, the cases where magnetization M1 and magnetization M2 are parallel or antiparallel in the initial state are illustrated, but it is also possible that magnetization M1 and magnetization M2 are orthogonal in the initial state. For example, in the initial state, the case where magnetization M1 of the first ferromagnetic layer 1 is oriented in any direction along the xy plane in an in-plane magnetized film, and magnetization M2 of the second ferromagnetic layer 2 is oriented perpendicularly along the z direction is equivalent to this case. Since magnetization M1 is oriented in any direction in the xy plane due to magnetic anisotropy, and magnetization M2 is oriented along the z direction, magnetization M1 and magnetization M2 are orthogonal in the initial state.

[0134] Figure 11 and Figure 12 This diagram illustrates another example of the second operation of the magnetic element 10 in the first embodiment. Figure 11 and Figure 12 In the illustration, only the first ferromagnetic layer 1, the second ferromagnetic layer 2, and the spacer layer 3 of the magnetic element 10 are shown. Figure 11 and Figure 12 The direction of the induced current Is applied to the magnetic element 10 is different. Figure 11 The induced current Is flows from the first ferromagnetic layer 1 toward the second ferromagnetic layer 2. Figure 12 The induced current Is flows from the second ferromagnetic layer 2 toward the first ferromagnetic layer 1.

[0135] exist Figure 11 and Figure 12 In any of the cases, an induced current Is flows through the magnetic element 10, and in the initial state, a spin-transfer torque acts on the magnetization M1. Figure 11 In this case, the spin-transfer torque takes effect, making the magnetization M1 parallel to the magnetization M2 of the second ferromagnetic layer 2. Figure 12 In this case, the spin-transfer torque takes effect, making the magnetization M1 antiparallel to the magnetization M2 of the second ferromagnetic layer 2. Figure 11 and Figure 12 In any of the cases, in the initial state, because the effect of magnetic anisotropy on magnetization M1 is greater than the effect of spin-transfer torque, magnetization M1 is oriented in any direction within the xy plane.

[0136] If the intensity of light irradiating the first ferromagnetic layer 1 increases, the magnetization M1 of the first ferromagnetic layer 1 tilts from its initial state due to the external energy based on the light irradiation. This is because the sum of the effects of the light irradiation applied to the magnetization M1 and the effects of the spin-transfer torque is greater than the effect of the magnetic anisotropy of the magnetization M1. If the intensity of light irradiating the first ferromagnetic layer 1 increases, Figure 11 In this case, the magnetization M1 is tilted in a manner parallel to the magnetization M2 of the second ferromagnetic layer 2. Figure 12 In this case, magnetization M1 is tilted in an antiparallel manner to magnetization M2 of the second ferromagnetic layer 2. Because the directions of the spin-transfer torque acting on magnetization M1 are different, Figure 11 and Figure 12 The tilt direction of the magnetization M1 is different.

[0137] If the intensity of the light irradiating the first ferromagnetic layer 1 increases, then in Figure 11 In this case, the resistance of magnetic element 10 decreases, and the output voltage from magnetic element 10 decreases. Figure 12 In this case, the resistance of the magnetic element 10 increases, and the output voltage from the magnetic element 10 increases.

[0138] If the intensity of the light irradiating the first ferromagnetic layer 1 returns to the first intensity, the magnetization M1 of the first ferromagnetic layer 1 is restored due to the effect of magnetic anisotropy on the magnetization M1. As a result, the magnetic element 10 returns to its initial state.

[0139] Here, an example is given where the first ferromagnetic layer 1 is an in-plane magnetization film and the second ferromagnetic layer 2 is a perpendicular magnetization film, but the relationship can also be reversed. That is, in the initial state, magnetization M1 is oriented along the z-direction, and magnetization M2 is oriented along any direction in the xy-plane.

[0140] As described above, the light detection element 100 of the first embodiment uses the superlens 20 to focus light toward the magnetic element 10, replacing the light irradiated toward the magnetic element 10 with the output voltage from the magnetic element 10, thereby enabling the light to be replaced with an electrical signal.

[0141] Furthermore, the smaller the volume of the first ferromagnetic layer 1, the more easily the magnetization M1 of the first ferromagnetic layer 1 changes in response to light irradiation. That is, the smaller the volume of the first ferromagnetic layer 1, the more easily the magnetization M1 of the first ferromagnetic layer 1 tilts due to light irradiation, or the more easily it decreases due to light irradiation. In other words, if the volume of the first ferromagnetic layer 1 is reduced, even a small amount of light can change the magnetization M1. That is, the light detection element 100 of the first embodiment can detect light with high sensitivity.

[0142] More precisely, the ease with which the magnetization M1 changes is determined by the magnitude of the product (KuV) of the magnetic anisotropy (Ku) and volume (V) of the first ferromagnetic layer 1. The smaller the KuV, the more the magnetization M1 changes, even with very small light quantities; conversely, the larger the KuV, the less the magnetization M1 changes unless the light quantity is significantly larger. In other words, the KuV of the first ferromagnetic layer 1 is designed according to the amount of light emitted from the outside used in the application. In the case of operations involving extremely small light quantities and photon detection, reducing the KuV of the first ferromagnetic layer 1 enables the detection of such minute light quantities. This is a significant advantage, as reducing the element size makes the detection of such minute light quantities difficult in conventional pn junction semiconductors. In other words, reducing the volume of the first ferromagnetic layer 1 (i.e., reducing the element area) or the thickness of the first ferromagnetic layer 1 in order to reduce the KuV also enables photon detection.

[0143] Furthermore, the larger the area of ​​the superlens 20, the greater the amount of light converged towards the magnetic element 10 through the superlens 20. Even with a small amount of light, the magnetic element 10 can convert light into an electrical signal, thus reducing the area of ​​the superlens 20. By reducing the area of ​​the superlens 20 by matching the magnetic element 10, the photodetector 100 can be integrated at a high density.

[0144] The optical detection element described above can be applied to optical sensor devices such as receiving devices in communication systems and image sensors.

[0145] (First application example)

[0146] Figure 13 This is a conceptual diagram of the optical sensor device 200 in the first application example. Figure 13 The optical sensor device 200 shown has an optical sensor unit 110 and a semiconductor circuit 120.

[0147] The light sensor unit 110, for example, has a plurality of light detection elements 100. The light detection elements 100 are the light detection elements described above. Each light detection element 100 functions as a light sensor. Preferably, the light detection elements 100 operate in a second operation manner. The light detection elements 100 are arranged, for example, in a matrix-like two-dimensional arrangement. The light detection elements 100 are respectively connected to a first selection line extending in the row direction and a second selection line extending in the column direction. The light sensor unit 110 uses the plurality of light detection elements 100 to detect light and replace it with an electrical signal.

[0148] The semiconductor circuit 120 is disposed, for example, on the outer periphery of the light sensor unit 110. Alternatively, the semiconductor circuit 120 may be formed on the circuit board 101 described later, at a position overlapping with the light sensor unit 110 along the z-direction.

[0149] Semiconductor circuit 120 is electrically connected to each of the photodetector elements 100. Semiconductor circuit 120 processes the electrical signals sent from photosensor unit 110. Semiconductor circuit 120 has, for example, a row decoder 121 and a column decoder 122. The row decoder 121 and column decoder 122 determine the position of the photodetector element 100 that has detected light. In addition to row decoder 121 and column decoder 122, semiconductor circuit 120 may also have memory, arithmetic circuitry, registers, etc.

[0150] Figure 14 An example illustrating the specific structure of a light sensor unit. Figure 14 The illustrated light sensor unit 110 has multiple pixels p1. Each pixel p1 has, for example, a red sensor 100R, a green sensor 100G, a blue sensor 100B, an infrared sensor 100IR, and an ultraviolet sensor 100UV. The red sensor 100R, green sensor 100G, blue sensor 100B, infrared sensor 100IR, and ultraviolet sensor 100UV are each composed of a light detection element 100. Figure 14 The light sensor unit 110 shown illustrates an example where two high-visibility green sensors 100G are configured for one pixel p1, but this is not the only possibility. For example, at least one of the infrared sensor 100IR and the ultraviolet sensor 100UV can be removed.

[0151] The red sensor 100R, green sensor 100G, and blue sensor 100B each detect light in a specific wavelength region within a wavelength range of 380nm to 800nm ​​(hereinafter referred to as the first wavelength region). The blue sensor 100B, for example, detects light in a wavelength range of 380nm to 490nm. The green sensor 100G, for example, detects light in a wavelength range of 490nm to 590nm. The red sensor 100R, for example, detects light in a wavelength range of 590nm to 800nm. The infrared sensor 100IR detects light in a specific wavelength region within a wavelength range of 800nm ​​to 1mm (hereinafter referred to as the second wavelength region). The ultraviolet sensor 100UV detects light in a specific wavelength region within a specific wavelength region within a wavelength range of 200nm to 380nm (hereinafter referred to as the third wavelength region).

[0152] exist Figure 14 In the example shown, for instance, the red sensor 100R, green sensor 100G, and blue sensor 100B can be considered as the first photodetector element, the infrared sensor 100IR as the second photodetector element, and the ultraviolet sensor 100UV as the third photodetector element. The first photodetector element is a photodetector element with a magnetic element 10 positioned at the focal point of light in a first wavelength region converged by the superlens 20. The second photodetector element is a photodetector element with a magnetic element 10 positioned at the focal point of light in a second wavelength region converged by the superlens 20. The third photodetector element is a photodetector element with a magnetic element 10 positioned at the focal point of light in a third wavelength region converged by the superlens 20. The first wavelength region, the second wavelength region, and the third wavelength region are different wavelength regions.

[0153] Figure 15 This is a conceptual cross-sectional view of the optical sensor device 200 according to the first embodiment. The optical sensor device 200 includes, for example, a circuit board 101, a wiring layer 105, and a plurality of light detection elements 100. The wiring layer 105 and each of the plurality of light detection elements 100 are formed on the circuit board 101.

[0154] The aforementioned semiconductor circuit 120 is formed on the circuit board 101. The circuit board 101, for example, has an analog-to-digital converter 102 and an output terminal 103. The electrical signal transmitted from the photodetector 100 is converted into digital data by the analog-to-digital converter 102 and output from the output terminal 103.

[0155] Wiring layer 105 has a plurality of wirings 106. An interlayer insulating film 107 is provided between the plurality of wirings 106. The wirings 106 electrically connect each of the photodetectors 100 to the circuit board 101 and to the various operational circuits formed on the circuit board 101. Each of the photodetectors 100 and the circuit board 101 are connected, for example, via through wirings that penetrate the interlayer insulating film 107 in the z-direction. By shortening the wiring distance between each of the photodetectors 100 and the circuit board 101, noise can be reduced.

[0156] Wiring 106 is conductive. Wiring 106 is, for example, Al, Cu, etc. Interlayer insulating film 107 is an insulator that insulates the wiring between multiple layers or between components. Interlayer insulating film 107 is, for example, an oxide, nitride, or oxynitride of Si, Al, or Mg, and can be made of the same material as insulating layer 90.

[0157] Furthermore, the wavelength filters 40 of the red sensor 100R, green sensor 100G, blue sensor 100B, infrared sensor 100IR, and ultraviolet sensor 100UV each transmit light in different wavelength regions. For example, the wavelength filter 40 of the red sensor 100R transmits light in a wavelength region of 590nm or higher and less than 800nm. For example, the wavelength filter 40 of the green sensor 100G transmits light in a wavelength region of 490nm or higher and less than 590nm. For example, the wavelength filter 40 of the blue sensor 100B transmits light in a wavelength region of 380nm or higher and less than 490nm. For example, the wavelength filter 40 of the infrared sensor 100IR transmits light in a specific wavelength region within a wavelength region of 800nm ​​or higher and less than 1mm. For example, the wavelength filter 40 of the ultraviolet sensor 100UV transmits light in a specific wavelength region within a wavelength region of 200nm or higher and less than 380nm.

[0158] In the plurality of photodetectors 100 constituting a pixel p1, the distance between the magnetic element 10 and the superlens 20 can also be equal. In this case, at least one of the photodetectors 100 constituting a pixel p1 has a different structure of the nanostructure 21 of the superlens 20 compared to the other photodetectors 100 constituting a pixel p1. For example, the nanostructure 21 of the superlens 20 of the red sensor 100R, green sensor 100G, blue sensor 100B, infrared sensor 100IR, and ultraviolet sensor 100UV are different from each other. The structure of the nanostructure 21 refers to, for example, the size of the top view shape of each nanostructure 21, the periodicity of the arrangement of the plurality of nanostructures, etc. For example, the structure of the nanostructure 21 of each superlens 20 can be set such that the focal distance of the superlens 20 of the red sensor 100R relative to light with a wavelength of 633nm, the focal distance of the superlens 20 of the green sensor 100G relative to light with a wavelength of 530nm, the focal distance of the superlens 20 of the blue sensor 100B relative to light with a wavelength of 430nm, the focal distance of the superlens 20 of the infrared sensor 100IR relative to light with a wavelength of 1530nm, and the focal distance of the superlens 20 of the ultraviolet sensor 100UV relative to light with a wavelength of 290nm are equal.

[0159] Figure 15 The light detection element 100 shown has a magnetic element 10 disposed below a superlens 20, but multiple magnetic elements 10 may also be disposed below a superlens 20.

[0160] Furthermore, this example illustrates a two-dimensional arrangement of the light detection elements 100, but it can also be done as follows: Figure 16 The light detection elements 100 are arranged in a one-dimensional array, as shown. Figure 16 The image shows an example where a pixel p2 is composed of a one-dimensional arrangement of a red sensor 100R, a green sensor 100G, a blue sensor 100B, an infrared sensor 100IR, and an ultraviolet sensor 100UV, but it may also be without one or more of these sensors. Additionally, multiple light detection elements 100 can detect light in the same wavelength range, and there is no particular limitation on the wavelength range detected by each light detection element 100.

[0161] In addition, the light sensor unit 110A can also be like Figure 17The illustrated optical sensor device 201 has multiple photodetector elements 100 with varying distances between the magnetic element 10 and the superlens 20. For example, it is also possible that at least one of the multiple photodetector elements 100 constituting a pixel p1 has a different distance between the superlens 20 and the magnetic element 10 compared to the other photodetector elements 100 constituting a pixel p1. In this case, the structure of the nanostructure 21 of the superlens 20 can also be identical among the multiple photodetector elements 100 constituting a pixel p1.

[0162] For example, in the red sensor 100R, green sensor 100G, and blue sensor 100B, the distances between the superlens 20 and the magnetic element 10 are different. In a particular superlens 20 structure, the focal distance of the superlens 20 relative to the light L varies depending on the wavelength of the light L. Regarding the red sensor 100R, the magnetic element 10 (in...) Figure 17 In the example, the first ferromagnetic layer 1) and the superlens 20 are separated by a first focal distance f1. Regarding the green sensor 100G, the magnetic element 10 (in...) Figure 17 In the example, the first ferromagnetic layer 1) and the superlens 20 are separated by a second focal distance f2. Regarding the blue sensor 100B, the magnetic element 10 (in...) Figure 17 In the example, the first ferromagnetic layer 1) and the superlens 20 are separated by a third focal distance f3. The first focal distance f1 is the focal distance of the superlens 20 relative to a specific wavelength of light (e.g., light with a wavelength of 633 nm) within the wavelength region of light (red light) above 590 nm and below 800 nm. The second focal distance f2 is the focal distance of the superlens 20 relative to a specific wavelength of light (e.g., light with a wavelength of 530 nm) within the wavelength region of light (green light) above 490 nm and below 590 nm. The third focal distance f3 is the focal distance of the superlens 20 relative to a specific wavelength of light (e.g., light with a wavelength of 530 nm) within the wavelength region of light (blue light) above 380 nm and below 490 nm. The first focal distance f1 is shorter than the second focal distance f2, and the second focal distance f2 is shorter than the third focal distance f3.

[0163] The light sensor devices 200 and 201 measure the output voltage (resistance value of the magnetic element 10) of the magnetic element 10 of each light detection element 100 from the light sensor units 110 and 110A together with the position information obtained by the row decoder 121 and column decoder 122, and read the intensity of the light illuminating the light sensor unit 110. The light sensor devices 200 and 201 are used, for example, as image sensors. Such image sensors can be used in information terminal devices such as smartphones, tablets, personal computers, and digital cameras.

[0164] This concludes the illustration of one example of light sensor devices 200 and 201, but the light sensor devices are not limited to this example. For example, in light sensor units 110 and 110A, when using... Figure 2 In the case of the superlens 20 shown, or when the light incident on the light detection element 100 is polarized light such as laser light, the polarization filter 30 may not be necessary. Furthermore, the focal distance of light incident on a superlens 20 varies depending on the wavelength. Therefore, the superlens 20 itself functions as a wavelength filter, defining the wavelength region of light irradiating the magnetic element 10 with high intensity. If the wavelength filtering effect achieved by the superlens 20 is sufficient, the wavelength filter 40 may not be necessary.

[0165] (Second Application Example)

[0166] Figure 18 This is a conceptual diagram of the communication system 300 in the second application example. Figure 18 The communication system 300 shown includes multiple transceiver devices 301 and fiber optic cables (FBs) connecting the transceiver devices 301. The communication system 300 can be used for short- and medium-distance communication, such as within and between data centers, and long-distance communication, such as between cities. The transceiver devices 301 are, for example, located within a data center. The fiber optic cables (FBs) connect data centers, for example. The communication system 300 enables communication between the transceiver devices 301, for example, via the fiber optic cables (FBs). The communication system 300 can also enable wireless communication between the transceiver devices 301 without using fiber optic cables (FBs).

[0167] Figure 19 This is a block diagram of the transceiver 301 in the second application example. The transceiver 301 includes a receiving device 310 and a transmitting device 320. The receiving device 310 receives optical signal L1, and the transmitting device 320 transmits optical signal L2. The light used in the transmission and reception between the transceivers 301 via the optical fiber FB is, for example, near-infrared light with a wavelength of 1000 nm or more and 2000 nm or less.

[0168] The receiving device 310 includes, for example, a light detection element 100 and a signal processing unit 311. The light detection element 100 is the aforementioned light detection element that converts the light signal L1 into an electrical signal. Light containing the light signal L1 with varying light intensity is irradiated onto the light detection element 100. Alternatively, light passing through a waveguide may be irradiated onto the light detection element 100. The light irradiated onto the light detection element 100 (magnetic element 10) is, for example, a laser beam. The signal processing unit 311 processes the electrical signal converted by the light detection element 100. By processing the electrical signal generated from the light detection element 100, the signal processing unit 311 receives the signal contained in the light signal L1.

[0169] Figure 20This is a magnified schematic diagram of the vicinity of the optical detection element 100 in the communication system 300 of the second application example. For example, light propagating in the optical fiber FB, which serves as a waveguide, is focused by the superlens 20 and reaches the magnetic element 10. Figure 20 The light detection element 100 shown can also be used with Figure 6 It also has a polarization filter 30.

[0170] The transmitting device 320 includes, for example, a light source 321, an electrical signal generating element 322, and an optical modulation element 323. The light source 321 is, for example, a laser element. The light source 321 may also be, for example, an LED element. The light emitted by the light source 321 may be light of a single wavelength (monochromatic light). The light source 321 may also be located outside the transmitting device 320. The electrical signal generating element 322 generates an electrical signal based on the transmitted information. The electrical signal generating element 322 may also be integrated with the signal conversion element of the signal processing unit 311. The optical modulation element 323 modulates the light output from the light source 321 based on the electrical signal generated by the electrical signal generating element 322, and outputs an optical signal L2.

[0171] Furthermore, this demonstrates the application of the transceiver device to... Figure 18 The example shown is of communication system 300, but communication systems are not limited to this case.

[0172] For example, Figure 21 This is a conceptual diagram of another example of a communication system. Figure 21 The communication system 300A shown is for communication between two portable terminal devices 350. The portable terminal devices 350 are, for example, smartphones, tablets, etc.

[0173] Each portable terminal device 350 includes a receiving device 310 and a transmitting device 320. The receiving device 310 of another portable terminal device 350 receives an optical signal transmitted from the transmitting device 320 of one portable terminal device 350. The transmission and reception of optical signals between the portable terminal devices 350 are wireless. The light used for transmission and reception between the portable terminal devices 350 is, for example, visible light. The light used for transmission and reception between the portable terminal devices 350 may also be, for example, near-infrared light with a wavelength of 800 nm or more and 2500 nm or less. The aforementioned light detection element is used as the light detection element 100 of each receiving device 310. In this case, light containing the optical signal transmitted from the transmitting device 320 can propagate through a waveguide in the receiving device 310 and then illuminate the light detection element 100, or it can illuminate the light detection element 100 without passing through a waveguide.

[0174] In addition, for example, Figure 22 This is a conceptual diagram of another example of a communication system. Figure 22The communication system 300B shown is for communication between a portable terminal device 350 and an information processing device 360. The information processing device 360 ​​is, for example, a personal computer.

[0175] The portable terminal device 350 includes a transmitting device 320, and the information processing device 360 ​​includes a receiving device 310. Optical signals transmitted from the transmitting device 320 of the portable terminal device 350 are received by the receiving device 310 of the information processing device 360. The transmission and reception of optical signals between the portable terminal device 350 and the information processing device 360 ​​are wireless. The light used for transmission and reception between the portable terminal device 350 and the information processing device 360 ​​is, for example, visible light. The light used for transmission and reception between the portable terminal device 350 and the information processing device 360 ​​may also be, for example, near-infrared light with a wavelength of 800 nm or more and 2500 nm or less. The aforementioned light detection element is used as the light detection element 100 of the receiving device 310.

[0176] The present invention is not limited to the above-described embodiments and variations. Various modifications and alterations can be made within the scope of the spirit of the present invention as described in the claims.

[0177] Explanation of reference numerals in the attached figures

[0178] 1…First ferromagnetic layer, 2…Second ferromagnetic layer, 3…Spacer layer, 4…Buffer layer, 5…Seed layer, 6…Third ferromagnetic layer, 7…Magnetic coupling layer, 8…Vertical magnetization sensing layer, 9…Covering layer, 10…Magnetic element, 11…First electrode, 12…Second electrode, 15…Laminated structure, 20, 20A…Superlens, 21, 21A…Nanostructure, 22…Matrix, 23, 23A…Unit, 30…Polarization filter, 40…Wavelength filter, 90, 91…Insulating layer, 100…Photodetector element, 100B…Blue sensor, 100G…Green sensor, 100R…Red sensor, 100IR…Infrared sensor, 100UV…Ultraviolet sensor 101…Circuit board, 102…Analog-to-digital converter, 103…Output terminal, 105…Wiring layer, 106…Wiring, 107…Interlayer insulation layer, 110…Sensor unit, 120…Semiconductor circuit, 121…Row decoder, 122…Column decoder, 200, 201…Optical sensor device, 300, 300A, 300B…Communication system, 301…Transceiver device, 310…Receiver device, 311…Signal processing unit, 320…Transmitter device, 321…Light source, 322…Electrical signal generating element, 323…Optical modulation element, 350…Information terminal device, 360…Information processing device, L…Light, L1, L2…Optical signal, p1, p2…Pixel.

Claims

1. A photodetector element, comprising: Superlenses, which have multiple nanostructures arranged in a two-dimensional pattern; A magnetic element comprising a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer. Light that has passed through the superlens is shone onto the magnetic element. The magnetic element functions as an optical detection element. In the superlens corresponding to the aforementioned photodetector element, multiple nanostructures are periodically arranged. The output voltage from the magnetic element varies in multiple values ​​depending on the intensity of the light irradiated onto the first ferromagnetic layer.

2. The optical detection element according to claim 1, wherein, When viewed from above, the superlens has a first region. The top-view area of ​​each of the multiple nanostructures enclosed in the first region decreases as it moves outward from the center of the first region.

3. The optical detection element according to claim 2, wherein, When viewed from above, the arrangement plane of the multiple nanostructures also has an annular region on the outer side of the first region. The top-view area of ​​each of the multiple nanostructures enclosed in the annular region decreases from the inner periphery to the outer periphery of the annular region.

4. The optical detection element according to claim 1, wherein, When viewed from above, the arrangement plane of the plurality of nanostructures has a long side direction and a short side direction in its top view. The top-view shape of at least one of the plurality of nanostructures is configured at an angle different from that of the other nanostructures.

5. The optical detection element according to any one of claims 1 to 4, wherein, The magnetic element is positioned at the focal point of the light converged by the superlens.

6. The optical detection element according to claim 5, wherein, The light is light in a specific wavelength region within the wavelength range of 380 nm and above and less than 800 nm.

7. The optical detection element according to claim 5, wherein, The light is light in a specific wavelength region within the wavelength range of 800nm ​​and 1mm.

8. The optical detection element according to claim 5, wherein, The light is light in a specific wavelength region within the wavelength range of 200 nm to less than 380 nm.

9. A light sensor unit having multiple light detection elements, The plurality of optical detection elements are optical detection elements according to any one of claims 1 to 8.

10. The optical sensor unit according to claim 9, wherein, The plurality of optical detection elements includes at least a first optical detection element and a second optical detection element. The magnetic element is disposed at the focal point of the light in the first wavelength region converged by the superlens in the first photodetector element. The second photodetector has the magnetic element positioned at the focal point of light from a second wavelength region, which is different from the first wavelength region, converged by the superlens.

11. The optical sensor unit according to claim 10, wherein, The first wavelength region is a specific wavelength region within the wavelength region above 380nm and below 800nm. The second wavelength region is a specific wavelength region within the wavelength region above 800nm ​​and below 1mm.

12. The optical sensor unit according to claim 10 or 11, wherein, The plurality of optical detection elements also include a third optical detection element. The magnetic element is disposed at the focal point of light from a third wavelength region, which is different from the first and second wavelength regions, converged by the superlens. The third wavelength region is a specific wavelength region within the wavelength regions above 200nm and below 380nm.

13. The optical sensor unit according to any one of claims 9 to 12, wherein, The plurality of optical detection elements are arranged in one dimension.

14. The optical sensor unit according to any one of claims 9 to 12, wherein, The multiple optical detection elements are arranged in a two-dimensional pattern.

15. The optical sensor unit according to any one of claims 9 to 14, wherein, At least one of the photodetectors constituting a pixel among the plurality of photodetectors has a different structure from the other photodetectors constituting the pixel in the nanostructure of the superlens.

16. The optical sensor unit according to any one of claims 9 to 14, wherein, The distance between the superlens and the magnetic element is different between at least one of the photodetectors constituting a pixel and the other photodetectors constituting the pixel.

17. A receiving device having a light detection element according to any one of claims 1 to 8.

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