Photodetection element, receiving device, and photo sensor device

Abstract

To provide a light detection element making a good response to light, a receiving device and an optical sensor device.SOLUTION: A light detection element 100 has a magnetic element 10 comprising a first ferromagnetic layer 1, a second ferromagnetic layer 2, and a spacer layer 3 sandwiched between the first ferromagnetic layer 1 and second ferromagnetic layer 2. The first ferromagnetic layer 1 is irradiated with light L from a direction crossing a laminating direction of the magnetic element 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a light detection element, a receiving device, and a light sensor device. [Background technology]

[0002] Photoelectric conversion elements are used for a variety of purposes.

[0003] For example, Patent Document 1 describes a receiving device that receives an optical signal using a photodiode. The photodiode is, for example, a pn junction diode that uses a semiconductor pn junction, and converts light into an electrical signal.

[0004] Furthermore, for example, Patent Document 2 describes an optical sensor using a semiconductor pn junction and an image sensor using this optical sensor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-292107 [Patent Document 2] U.S. Patent No. 9,842,874 Summary of the Invention [Problem to be solved by the invention]

[0006] Photodetectors using semiconductor pn junctions are widely used, but new photodetectors are needed for further development. Furthermore, photodetectors convert light into electrical signals, and there is a need for improved conversion accuracy.

[0007] The present invention has been made in view of the above problems, and has as its object to provide a light detection element, a receiving device, and a light sensor device that have good response to light. [Means for solving the problem]

[0008] In order to solve the above problems, the following means are provided.

[0009] (1) A first aspect of the light detection element has a magnetic element including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer, and light is irradiated onto the first ferromagnetic layer from a direction intersecting the stacking direction of the magnetic element.

[0010] (2) The light detection element according to the above aspect may further include a first electrode and a second electrode sandwiching the magnetic element in the stacking direction, and at least one side surface of the first electrode or the second electrode and a side surface of the magnetic element may be in contact with the same imaginary plane at least in part, and the light may be irradiated onto the first ferromagnetic layer from the imaginary plane side.

[0011] (3) The light-detecting element according to the above aspect may be configured such that a part of the side surface of the magnetic element is a flat surface, and the light is irradiated onto the flat surface.

[0012] (4) In the light-detecting element according to the above aspect, a part of the side surface of the magnetic element may be a flat surface, and the flat surface may be in contact with the imaginary plane.

[0013] (5) The light-detecting element according to the above aspect may further include an oxide film that covers the flat surface and is capable of transmitting light.

[0014] (6) The light-detecting element according to the above aspect may further include a heat generating portion, and the heat generating portion may be located behind the magnetic element in the light irradiation direction in which the light is mainly irradiated onto the magnetic element.

[0015] (7) The light detection element according to the above aspect may further have an expansion portion, the heat generating portion being located in a position capable of heating the expansion portion, the expansion portion being located behind the magnetic element in the light irradiation direction in which the light is mainly irradiated onto the magnetic element, and the expansion portion having a linear thermal expansion coefficient greater than that of the first ferromagnetic layer.

[0016] (8) In the light-sensing element according to the above aspect, the light may be light that includes a high-frequency optical signal and whose intensity changes.

[0017] (9) In the photodetector according to the above aspect, the light may be light that has passed through a wavelength filter.

[0018] (10) A receiving device according to a second aspect includes the photodetector element according to the above aspect.

[0019] (11) An optical sensor device according to a third aspect includes the optical detection element according to the above aspect. [Effects of the Invention]

[0020] The light detection element, receiving device, and light sensor device according to the above aspects have good responsiveness to light. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a perspective view of a light-detecting element according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the photodetector according to the first embodiment. [Figure 3] FIG. 2 is a plan view of the light-detecting element according to the first embodiment. [Figure 4] 5A and 5B are diagrams illustrating a first mechanism of a first operation example of the photodetector according to the first embodiment. [Figure 5] 5A and 5B are diagrams illustrating a second mechanism of the first operation example of the photodetector according to the first embodiment. [Figure 6] 5A and 5B are diagrams illustrating a first mechanism of a second operation example of the light-detecting element according to the first embodiment. [Figure 7] 10A and 10B are diagrams illustrating a second mechanism of a second operation example of the light-detecting element according to the first embodiment. [Figure 8] 10A and 10B are diagrams illustrating another example of the second operation example of the light-detecting element according to the first embodiment. [Figure 9]10A and 10B are diagrams illustrating another example of the second operation example of the light-detecting element according to the first embodiment. [Figure 10] FIG. 10 is a cross-sectional view of a light-detecting element according to a first modified example. [Figure 11] FIG. 10 is a cross-sectional view of a light-detecting element according to a second modified example. [Figure 12] FIG. 10 is a cross-sectional view of a light-detecting element according to a third modified example. [Figure 13] FIG. 10 is a cross-sectional view of a light-detecting element according to a fourth modified example. [Figure 14] FIG. 10 is a cross-sectional view of a photodetector according to a second embodiment. [Figure 15] FIG. 10 is a cross-sectional view of a light-detecting element according to a third embodiment. [Figure 16] FIG. 10 is a cross-sectional view of a light-detecting element according to a fourth embodiment. [Figure 17] FIG. 10 is a block diagram of a transmitting / receiving device according to a first application example. [Figure 18] FIG. 1 is a conceptual diagram of an example of a communication system. [Figure 19] FIG. 10 is a conceptual diagram of a cross section of an optical sensor device according to a second application example. [Figure 20] FIG. 2 is a schematic diagram of an example of a terminal device. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, the embodiments will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for convenience in order to make the features easier to understand, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate changes can be made within the scope of the effects of the present invention.

[0023] The directions are defined as follows. The stacking direction of the magnetic element 10 is the z direction, one direction in a plane perpendicular to the z direction is the x direction, and the direction perpendicular to the x and z directions is the y direction. The z direction is an example of a stacking direction. Hereinafter, the +z direction may be expressed as "up" and the -z direction as "down". The +z direction is the direction from the second ferromagnetic layer 2 to the first ferromagnetic layer 1. Up and down do not necessarily coincide with the direction in which gravity is applied.

[0024] "First embodiment" Fig. 1 is a perspective view of a photodetector 100 according to the first embodiment. Fig. 2 is a yz cross-sectional view of the photodetector 100 according to the first embodiment. Fig. 3 is a plan view of the photodetector 100 according to the first embodiment as viewed from the z direction.

[0025] The light detecting element 100 converts the state or change in state of the irradiated light L into an electrical signal. In this specification, light L is not limited to visible light but also includes infrared light, which has a longer wavelength than visible light, and ultraviolet light, which has a shorter wavelength than visible light. The wavelength of visible light is, for example, 380 nm or more and less than 800 nm. The wavelength of infrared light is, for example, 800 nm or more and 1 mm or less. The wavelength of ultraviolet light is, for example, 200 nm or more and less than 380 nm.

[0026] The light-detecting element 100 includes, for example, a magnetic element 10, a first electrode 20, a second electrode 30, a light emitting section 40, and an insulating layer 50.

[0027] The light irradiating unit 40 is, for example, a portion from which light L propagated from a light source is emitted. The light L emitted from the light irradiating unit 40 is irradiated onto the side surface 10s of the magnetic element 10. The light irradiating unit 40 faces the side surface 10s of the magnetic element 10, for example.

[0028] Light L is irradiated onto the magnetic element 10 from a direction intersecting the z direction. Light L is irradiated onto the side surface 10s of the magnetic element 10, for example, from the y direction. Hereinafter, the direction in which light is mainly irradiated onto the magnetic element 10 will be referred to as the light irradiation direction. "Mainly irradiated" means that the intensity of light irradiated from that direction is greater than the intensity of light irradiated from other directions. In Figures 1 and 2, the y direction is the light irradiation direction onto the magnetic element 10. Light L is, for example, light that includes a high-frequency optical signal and whose intensity changes, or light that has passed through a wavelength filter and has a controlled wavelength range. The high-frequency optical signal is, for example, a signal having a frequency of 100 MHz or more.

[0029] The first electrode 20 contacts a first surface of the magnetic element 10. The first surface is the surface of the magnetic element 10 facing the first ferromagnetic layer 1 in the z direction. The second electrode 30 contacts a second surface of the magnetic element 10. The second surface is the surface of the magnetic element 10 facing the second ferromagnetic layer 2 in the z direction. The first electrode 20 and the second electrode 30 sandwich the magnetic element 10 in the z direction, for example.

[0030] The first electrode 20 and the second electrode 30 are made of a conductive material. The first electrode 20 and the second electrode 30 are made of a metal such as Cu, Al, Au, or Ru. Ta or Ti may be laminated above and below these metals. The first electrode 20 and the second electrode 30 may also be a laminated film of Cu and Ta, a laminated film of Ta, Cu, and Ti, or a laminated film of Ta, Cu, and TaN. The first electrode 20 and the second electrode 30 may also be made of TiN or TaN.

[0031] The first electrode 20 and the second electrode 30 may be transparent to the wavelength range of light irradiated onto the magnetic element 10. For example, the first electrode 20 and the second electrode 30 may be transparent electrodes containing an oxide transparent electrode material such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), or indium gallium zinc oxide (IGZO). The first electrode 20 and the second electrode 30 may also be configured to have a plurality of metal pillars in these transparent electrode materials.

[0032] The insulating layer 50 is located between the first electrode 20 and the second electrode 30. The insulating layer 50 covers, for example, the magnetic element 10 except for the side surface 10s on which the light L is irradiated. The insulating layer 50 is an interlayer insulating film. The insulating layer 50 is, for example, an oxide, nitride, or oxynitride of Si, Al, or Mg. The insulating layer 50 is, for example, silicon oxide (SiO x ), silicon nitride (SiN x ), silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al2O3), zirconium oxide (ZrO x ) etc.

[0033] When the state of the irradiated light L changes, the resistance value of the magnetic element 10 in the z direction changes in accordance with the change in the state of the light L. When the state of the irradiated light L to the magnetic element 10 changes, the output voltage from the magnetic element 10 changes in accordance with the change in the state of the light L. The magnetic element 10 has, for example, 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. The magnetic element 10 may have other layers in addition to these.

[0034] A portion of the side surface of the magnetic element 10 is irradiated with light. For example, the side surface 10s is irradiated with light. The side surface 10s is the side surface of the magnetic element 10 that is primarily irradiated with light L. The intensity of the light irradiated to the side surface 10s is greater than the intensity of the light irradiated to the other side surfaces. The side surface 10s is, for example, a light-receiving surface for the light L.

[0035] A part of the side surface of the magnetic element 10 is flat. For example, the side surface 10s is flat. For example, the light L is irradiated onto the side surface 10s, which is a flat surface.

[0036] The side surface of the magnetic element 10 and the side surface of at least one of the first electrode 20 and the second electrode 30 are at least partially in contact with the same imaginary plane VS. The imaginary plane VS is one of the tangent planes to the side surface of the magnetic element 10. Light L is irradiated onto the first ferromagnetic layer 1 from the imaginary plane VS side.

[0037] For example, the side surface 10s, the side surface 20s of the first electrode 20, and the side surface 30s of the second electrode 30 are in contact with the same imaginary plane VS. The side surface 10s, the side surface 20s, and the side surface 30s are continuous. The side surface 20s is the side surface of the first electrode 20 that is mainly irradiated with light L. The side surface 30s is the side surface of the second electrode 30 that is mainly irradiated with light L.

[0038] The magnetic element 10 is, for example, an MTJ (Magnetic Tunnel Junction) element in which the spacer layer 3 is made of an insulating material. In this case, the resistance value in the z direction (the resistance value when a current flows in the z direction) of the magnetic element 10 changes according to the relative change between the magnetization state of the first ferromagnetic layer 1 and the magnetization state of the second ferromagnetic layer 2. Such an element is also called a magnetoresistance effect element.

[0039] The first ferromagnetic layer 1 is a light detection layer whose magnetization state changes when irradiated with light from the outside. The first ferromagnetic layer 1 is also called a magnetization free layer. The magnetization free layer is a layer containing a magnetic material whose magnetization state changes when a predetermined external force is applied. The predetermined external force is, for example, light L irradiated from the outside, a current flowing in the z direction of the magnetic element 10, or an external magnetic field. The magnetization state of the first ferromagnetic layer 1 changes depending on the intensity of the light L irradiated to the first ferromagnetic layer 1.

[0040] The first ferromagnetic layer 1 includes a ferromagnetic material. The first ferromagnetic layer 1 includes at least one of magnetic elements such as Co, Fe, or Ni. The first ferromagnetic layer 1 may include a non-magnetic element such as B, Mg, Hf, or Gd in addition to the magnetic elements described above. The first ferromagnetic layer 1 may be, for example, an alloy including a magnetic element and a non-magnetic element. The first ferromagnetic layer 1 may be composed of multiple layers. The first ferromagnetic layer 1 may be, for example, a CoFeB alloy, a stacked body in which a CoFeB alloy layer is sandwiched between Fe layers, or a stacked body in which a CoFeB alloy layer is sandwiched between CoFe layers.

[0041] The first ferromagnetic layer 1 may be an in-plane magnetization film having an axis of easy magnetization in the in-plane direction (any direction in the xy plane) or a perpendicular magnetization film having an axis of easy magnetization in the direction perpendicular to the film plane (z direction).

[0042] The thickness of the first ferromagnetic layer 1 is, for example, 1 nm or more and 5 nm or less. The thickness of the first ferromagnetic layer 1 is preferably, for example, 1 nm or more and 2 nm or less. When the first ferromagnetic layer 1 is a perpendicular magnetization film, if the thickness of the first ferromagnetic layer 1 is thin, the effect of perpendicular magnetic anisotropy applied from the layers above and below the first ferromagnetic layer 1 is strengthened, and the perpendicular magnetic anisotropy of the first ferromagnetic layer 1 is increased. In other words, if the perpendicular magnetic anisotropy of the first ferromagnetic layer 1 is high, the force that causes the magnetization M1 to return to the z-direction is strengthened. On the other hand, if the thickness of the first ferromagnetic layer 1 is thick, the effect of perpendicular magnetic anisotropy applied 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.

[0043] As the thickness of the first ferromagnetic layer 1 decreases, its volume as a ferromagnetic material decreases, and as it increases, its volume as a ferromagnetic material increases. The responsiveness of the magnetization of the first ferromagnetic layer 1 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. In other words, as the product of the magnetic anisotropy and volume of the first ferromagnetic layer 1 decreases, its responsiveness to light increases. From this perspective, in order to enhance its responsiveness 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.

[0044] If the thickness of the first ferromagnetic layer 1 is greater than 2 nm, an insertion layer made of, for example, Mo or W may be provided within the first ferromagnetic layer 1. That is, the first ferromagnetic layer 1 may be a stack in which a ferromagnetic layer, an insertion layer, and a ferromagnetic layer are stacked in this order in the z direction. The interfacial magnetic anisotropy at the interface between the insertion layer and the ferromagnetic layer enhances the perpendicular magnetic anisotropy of the entire first ferromagnetic layer 1. The thickness of the insertion layer is, for example, 0.1 nm to 0.6 nm.

[0045] The second ferromagnetic layer 2 is a magnetization fixed layer. The magnetization fixed layer is a layer made of a magnetic material whose magnetization state is less likely to change when a predetermined external energy is applied than the magnetization free layer. For example, the magnetization direction of the magnetization fixed layer is less likely to change when a predetermined external energy is applied than the magnetization free layer. Also, for example, the magnitude of the magnetization of the magnetization fixed layer is less likely to change when a predetermined external energy is applied than the magnetization free layer. The coercive force of the second ferromagnetic layer 2 is, for example, greater than the coercive force of the first ferromagnetic layer 1. The second ferromagnetic layer 2 has an easy axis of magnetization in the same direction as the first ferromagnetic layer 1, for example. The second ferromagnetic layer 2 may be an in-plane magnetization film or a perpendicular magnetization film.

[0046] 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 may be, for example, a laminate in which Co is 0.4 nm to 1.0 nm thick, Mo is 0.1 nm to 0.5 nm thick, a CoFeB alloy is 0.3 nm to 1.0 nm thick, and Fe is 0.3 nm to 1.0 nm thick are laminated in this order.

[0047] The magnetization of the second ferromagnetic layer 2 may be fixed by magnetic coupling with a third ferromagnetic layer via a magnetic coupling layer, for example. In this case, the combination of the second ferromagnetic layer 2, the magnetic coupling layer, and the third ferromagnetic layer may be referred to as a magnetization fixed layer.

[0048] The third ferromagnetic layer is magnetically coupled to the second ferromagnetic layer 2, for example. The magnetic coupling is, for example, an antiferromagnetic coupling caused by RKKY interaction. The material constituting the third ferromagnetic layer is, for example, the same as that of the first ferromagnetic layer 1. The magnetic coupling layer is, for example, Ru, Ir, or the like.

[0049] The spacer layer 3 is a non-magnetic layer disposed between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. The spacer layer 3 is composed of a layer made of a conductor, an insulator, or a semiconductor, or a layer containing current-carrying points made of a conductor in an insulator. The thickness of the spacer layer 3 can be adjusted depending on the orientation directions of the magnetizations of the first ferromagnetic layer 1 and the second ferromagnetic layer 2 in the initial state, which will be described later.

[0050] For example, when the spacer layer 3 is made of an insulator, the magnetic element 10 has a magnetic tunnel junction (MTJ) consisting of the first ferromagnetic layer 1, the spacer layer 3, and the second ferromagnetic layer 2. Such an element is called an MTJ element. In this case, the magnetic element 10 can exhibit a tunnel magnetoresistance (TMR) effect. When the spacer layer 3 is made of a metal, the magnetic element 10 can exhibit a giant magnetoresistance (GMR) effect. Such an element is called a GMR element. The magnetic element 10 may be called an MTJ element, a GMR element, or other names depending on the material of the spacer layer 3, but is also collectively called a magnetoresistance effect element.

[0051] When the spacer layer 3 is made of an insulating material, a material containing aluminum oxide, magnesium oxide, titanium oxide, silicon oxide, or the like can be used. These insulating materials may also contain elements such as Al, B, Si, and Mg, or magnetic elements such as Co, Fe, and Ni. A high magnetoresistance ratio can be obtained by adjusting the thickness of the spacer layer 3 so that a high TMR effect is exhibited between the first ferromagnetic layer 1 and the second ferromagnetic layer 2. To efficiently utilize the TMR effect, the thickness of the spacer layer 3 may be approximately 0.5 to 5.0 nm, or approximately 1.0 to 2.5 nm.

[0052] When the spacer layer 3 is made of a nonmagnetic conductive material, conductive materials such as Cu, Ag, Au, or Ru can be used. To efficiently utilize the GMR effect, the thickness of the spacer layer 3 may be about 0.5 to 5.0 nm, or about 2.0 to 3.0 nm.

[0053] When the spacer layer 3 is made of a non-magnetic semiconductor material, it can be made of zinc oxide, indium oxide, tin oxide, germanium oxide, gallium oxide, ITO, etc. In this case, the thickness of the spacer layer 3 may be about 1.0 to 4.0 nm.

[0054] When a layer including current-carrying points formed by a conductor in a nonmagnetic insulator is used as the spacer layer 3, the current-carrying points may be formed by a nonmagnetic conductor such as Cu, Au, or Al in a nonmagnetic insulator made of aluminum oxide or magnesium oxide. The conductor may also be made of a magnetic element such as Co, Fe, or Ni. In this case, the thickness of the spacer layer 3 may be approximately 1.0 to 2.5 nm. The current-carrying points are, for example, columnar bodies with a diameter of 1 nm to 5 nm when viewed perpendicular to the film surface.

[0055] The magnetic element 10 may also have an underlayer, a cap layer, a perpendicular magnetization induction layer, etc. The underlayer is located between the second ferromagnetic layer 2 and the second electrode 30. The underlayer is a seed layer or a buffer layer. The seed layer improves the crystallinity of the layer stacked on the seed layer. The seed layer is, for example, Pt, Ru, Hf, Zr, or NiFeCr. The thickness of the seed layer is, for example, 1 nm or more and 5 nm or less. The buffer layer is a layer that alleviates lattice mismatch between different crystals. The buffer layer is, for example, Ta, Ti, W, Zr, Hf, or nitrides of these elements. The thickness of the buffer layer is, for example, 1 nm or more and 5 nm or less.

[0056] The cap layer is located between the first ferromagnetic layer 1 and the first electrode 20. The cap layer prevents damage to the lower layer during the process and improves the crystallinity of the lower layer during annealing. The thickness of the cap layer is, for example, 3 nm or less so that the first ferromagnetic layer 1 is irradiated with sufficient light. The cap layer is, for example, made of MgO, W, Mo, Ru, Ta, Cu, Cr, or a laminated film of these materials.

[0057] The perpendicular magnetization induction layer is formed when the first ferromagnetic layer 1 is a perpendicular magnetization film. The perpendicular magnetization induction layer is stacked on the first ferromagnetic layer 1. The perpendicular magnetization induction layer induces perpendicular magnetic anisotropy in the first ferromagnetic layer 1. The perpendicular magnetization induction layer is made of, for example, magnesium oxide, W, Ta, Mo, etc. When the perpendicular magnetization induction layer is made of magnesium oxide, it is preferable that the magnesium oxide has oxygen deficiency to increase conductivity. The film thickness of the perpendicular magnetization induction layer is, for example, 0.5 nm or more and 2.0 nm or less.

[0058] The photodetector element 100 is fabricated through a process of stacking each layer, an annealing process, and a processing process. First, the second electrode 30, the second ferromagnetic layer 2, the spacer layer 3, and the first ferromagnetic layer 1 are stacked in this order on a substrate. Each layer is formed by, for example, sputtering.

[0059] Next, the laminated film is annealed. The annealing temperature is, for example, 250°C to 450°C. When the substrate is a circuit board, it is preferable to anneal at 400°C or higher. Thereafter, the laminated film is processed into a predetermined columnar shape by photolithography and etching. The columnar shape may be a cylindrical or rectangular columnar shape. For example, the minimum width of the columnar shape when viewed from the z direction may be 10 nm to 2000 nm, or 30 nm to 500 nm.

[0060] Next, an insulating layer 50 is formed so as to cover the side surfaces of the columns. The insulating layer 50 may be stacked multiple times. Next, the top surface of the first ferromagnetic layer 1 is exposed from the insulating layer 50 by chemical mechanical polishing (CMP), and a first electrode 20 is formed on the first ferromagnetic layer 1.

[0061] Next, the substrate and the insulating layer 50 are cut. Then, the insulating layer 50 is removed from the cut surface by, for example, chemical mechanical polishing (CMP) and ion beam etching, thereby exposing the second electrode 30, the second ferromagnetic layer 2, the spacer layer 3, and the first ferromagnetic layer 1 from the insulating layer 50. This makes the side surface 10s flat, and the side surfaces 30s, 10s, and 20s are continuous. Finally, the light irradiator 40 is disposed at a position facing the side surface 10s, thereby obtaining the photodetector element 100.

[0062] Next, several examples of the operation of the photodetector 100 will be described. The first ferromagnetic layer 1 is irradiated with light whose intensity varies. The output voltage from the photodetector 100 varies as the first ferromagnetic layer 1 is irradiated with light. In the first operation example, a case will be described in which the intensity of the light irradiated to the first ferromagnetic layer 1 has two levels: a first intensity and a second intensity. The intensity of the light with the second intensity is greater than the intensity of the light with the first intensity. The first intensity may also be zero when the intensity of the light irradiated to the first ferromagnetic layer 1 is zero.

[0063] 4 and 5 are diagrams illustrating a first operation example of the photodetector element 100 according to the first embodiment. FIG. 4 is a diagram illustrating a first mechanism of the first operation example, and FIG. 5 is a diagram illustrating a second mechanism of the first operation example. In the upper graphs of FIGS. 4 and 5, the vertical axis represents the intensity of light irradiated onto the first ferromagnetic layer 1, and the horizontal axis represents time. In the lower graphs of FIGS. 4 and 5, the vertical axis represents the resistance value of the magnetic element 10 in the z direction, and the horizontal axis represents time.

[0064] First, in a state where the first ferromagnetic layer 1 is irradiated with light of a first intensity (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 of the magnetic element 10 in the z direction exhibits a first resistance value R1, and the magnitude of the output voltage from the magnetic element 10 exhibits a first value. The resistance value of the magnetic element 10 in the z direction is determined by Ohm's law from the voltage generated across both ends of the magnetic element 10 in the z direction by passing a sense current Is through the magnetic element 10 in the z direction. The output voltage from the magnetic element 10 is generated between the first electrode 20 and the second electrode 30. In the example shown in FIG. 4, the sense current Is is passed from the first ferromagnetic layer 1 to the second ferromagnetic layer 2. By passing the sense current Is in this direction, a spin transfer torque acts on the magnetization M1 of the first ferromagnetic layer 1 in the same direction as the magnetization M2 of the second ferromagnetic layer 2, and the magnetizations M1 and M2 become parallel in the initial state. Also, by passing the sense current Is in this direction, it is possible to prevent the magnetization M1 of the first ferromagnetic layer 1 from reversing during operation.

[0065] Next, the intensity of the light irradiated to the first ferromagnetic layer 1 changes from the 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 the magnetization M1 of the first ferromagnetic layer 1 when no light is irradiated to the first ferromagnetic layer 1 is different from the state of the magnetization M1 of the first ferromagnetic layer 1 at the second intensity. The state of the magnetization M1 refers to, for example, the tilt angle or magnitude with respect to the z direction.

[0066] For example, as shown in Fig. 4, when the intensity of light irradiated to the first ferromagnetic layer 1 changes from a first intensity to a second intensity, the magnetization M1 tilts with respect to the z direction. Furthermore, as shown in Fig. 5, when the intensity of light irradiated to the first ferromagnetic layer 1 changes from the 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 tilts with respect to the z direction due to the intensity of light irradiation, the tilt angle is greater than 0° and less than 90°.

[0067] When the magnetization M1 of the first ferromagnetic layer 1 changes from its initial state, the resistance value in the z direction of the magnetoresistive element 10 exhibits a second resistance value R2, and the magnitude of the output voltage from the magnetic element 10 exhibits a 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 is between the resistance value (first resistance value R1) when the magnetization M1 and the magnetization M2 are parallel and the resistance value when the magnetization M1 and the magnetization M2 are antiparallel.

[0068] In the case shown in FIG. 4, a spin transfer torque acts on the magnetization M1 of the first ferromagnetic layer 1 in the same direction as the magnetization M2 of the second ferromagnetic layer 2. Therefore, the magnetization M1 attempts to return to a state parallel to the magnetization M2, and when the intensity of the light irradiated to the first ferromagnetic layer 1 changes from the second intensity to the first intensity, the magnetic element 10 returns to its initial state. In the case shown in FIG. 5, when the intensity of the light irradiated to the first ferromagnetic layer 1 returns to the first intensity, the magnitude of the magnetization M1 of the first ferromagnetic layer 1 returns to its original value, and the magnetic element 10 returns to its initial state. In either 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 irradiated to the first ferromagnetic layer 1 changes from the second intensity to the first intensity, the resistance value in the z direction of the photodetector element 100 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.

[0069] The output voltage from the photodetector element 100 changes in response to changes in the intensity of light irradiated onto the first ferromagnetic layer 1, and the change in the intensity of the irradiated light can be converted into a change in the output voltage from the photodetector element 100. In other words, the photodetector element 100 can convert light into an electrical signal. For example, if the output voltage from the photodetector element 100 is equal to or greater than a threshold, it is processed as a first signal (e.g., "1"), and if it is less than the threshold, it is processed as a second signal (e.g., "0").

[0070] Here, the case where the magnetization M1 and the magnetization M2 are parallel in the initial state has been described as an example, but the magnetization M1 and the magnetization M2 may be antiparallel in the initial state. In this case, the resistance value in the z direction of the magnetic element 10 decreases as the state of the magnetization M1 changes (for example, as the angle change of the magnetization M1 from the initial state increases). If the initial state is one in which the magnetization M1 and the magnetization M2 are antiparallel, it is preferable to flow the sense current Is from the second ferromagnetic layer 2 toward the first ferromagnetic layer 1. By flowing the sense current Is in this direction, a spin transfer torque acts on the magnetization M1 of the first ferromagnetic layer 1 in the opposite direction to the magnetization M2 of the second ferromagnetic layer 2, and the magnetization M1 and the magnetization M2 become antiparallel in the initial state.

[0071] In the first operating example, the case where the light irradiated to the first ferromagnetic layer 1 has two levels of intensity, a first intensity and a second intensity, was described as an example, but in the second operating example, the case where the intensity of the light irradiated to the first ferromagnetic layer 1 changes in multiple levels or in an analog manner will be described.

[0072] 6 and 7 are diagrams illustrating a second operation example of the photo-detecting element 100 according to the first embodiment. FIG. 6 is a diagram illustrating a first mechanism of the first operation example, and FIG. 7 is a diagram illustrating a second mechanism of the first operation example. In the upper graphs of FIGS. 6 and 7, the vertical axis represents the intensity of light irradiated onto the first ferromagnetic layer 1, and the horizontal axis represents time. In the lower graphs of FIGS. 6 and 7, the vertical axis represents the resistance value of the magnetic element 10 in the z direction, and the horizontal axis represents time.

[0073] 6, as the intensity of light irradiated onto the first ferromagnetic layer 1 increases, the external energy caused by the light irradiation tilts the magnetization M1 of the first ferromagnetic layer 1 from its initial state. The angle between the direction of the magnetization M1 of the first ferromagnetic layer 1 when no light is irradiated onto the first ferromagnetic layer 1 and the direction of the magnetization M1 when light is irradiated onto the first ferromagnetic layer 1 is both greater than 0° and smaller than 90°.

[0074] When the magnetization M1 of the first ferromagnetic layer 1 tilts from its initial state, the resistance value in the z direction of the magnetoresistive element 10 changes. Consequently, 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 changes from a second resistance value R2 to a third resistance value R3 to a fourth resistance value R4, and the output voltage from the magnetic element 10 changes from a second value to a third value to a fourth value. The resistance values ​​increase in the order of the first resistance value R1, the second resistance value R2, the third resistance value R3, and the fourth resistance value R4. The output voltage from the magnetic element 10 increases in the order of the first value, the second value, the third value, and the fourth value.

[0075] When the intensity of light irradiated onto the first ferromagnetic layer 1 changes, the output voltage from the magnetic element 10 (the resistance value of the magnetic element 10 in the z-direction) 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," the photodetector element 100 can output four values. While the example shown here shows a case where four values ​​are read, the number of values ​​to be read can be freely designed by setting the threshold value of the output voltage from the magnetic element 10 (the resistance value of the magnetic element 10). The photodetector element 100 may also output analog values ​​as they are.

[0076] Similarly, in the case of FIG. 7, as the intensity of light irradiated onto the first ferromagnetic layer 1 increases, the magnitude of the magnetization M1 of the first ferromagnetic layer 1 decreases from its initial state due to external energy from the light irradiation. When the magnetization M1 of the first ferromagnetic layer 1 decreases from its initial state, the resistance value in the z direction of the magnetoresistive element 10 changes. Consequently, 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 changes from a second resistance value R2 to a third resistance value R3 to a fourth resistance value R4, and the output voltage from the magnetic element 10 changes from a second value to a third value to a fourth value. Therefore, similar to the case of FIG. 6, the light-detecting element 100 can output the difference in these output voltages (resistance values) as multi-value or analog data.

[0077] Also, in the second operating example, as in the first operating example, when the intensity of the light irradiated to the first ferromagnetic layer 1 returns to the first intensity, the state of the magnetization M1 of the first ferromagnetic layer 1 returns to its original state, and the magnetic element 10 returns to its initial state.

[0078] Here, the case where the magnetization M1 and the magnetization M2 are parallel in the initial state has been described as an example, but also in the second operation example, the magnetization M1 and the magnetization M2 may be antiparallel in the initial state.

[0079] Although the first and second operation examples illustrate cases in which the magnetization M1 and the magnetization M2 are parallel or antiparallel in the initial state, the magnetization M1 and the magnetization M2 may be orthogonal in the initial state. For example, this applies when the first ferromagnetic layer 1 is an in-plane magnetization film in which the magnetization M1 is oriented in one direction in the xy plane, and the second ferromagnetic layer 2 is a perpendicular magnetization film in which the magnetization M2 is oriented in the z direction. Due to magnetic anisotropy, the magnetization M1 is oriented in one direction in the xy plane, and the magnetization M2 is oriented in the z direction, so that the magnetization M1 and the magnetization M2 are orthogonal in the initial state.

[0080] 8 and 9 are diagrams illustrating another example of the second operation example of the photo-detecting element 100 according to the first embodiment. The flow direction of the sense current Is applied to the magnetic element 10 differs between FIGS. 8 and 9. In FIG. 8, the sense current Is flows from the first ferromagnetic layer 1 to the second ferromagnetic layer 2. In FIG. 9, the sense current Is flows from the second ferromagnetic layer 2 to the first ferromagnetic layer 1.

[0081] 8 and 9, a spin transfer torque acts on the magnetization M1 in the initial state when the sense current Is flows through the magnetic element 10. In the case of FIG. 8, the spin transfer torque acts so that the magnetization M1 becomes parallel to the magnetization M2 of the second ferromagnetic layer 2. In the case of FIG. 9, the spin transfer torque acts so that the magnetization M1 becomes antiparallel to the magnetization M2 of the second ferromagnetic layer 2. In both the cases of FIG. 8 and 9, in the initial state, the effect of magnetic anisotropy on the magnetization M1 is greater than the effect of the spin transfer torque, so that the magnetization M1 is oriented in one of the directions within the xy plane.

[0082] When the intensity of light irradiated onto 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 generated by the light irradiation. This is because the sum of the effect of the light irradiation and the effect of the spin transfer torque acting on the magnetization M1 becomes greater than the effect of the magnetic anisotropy associated with the magnetization M1. When the intensity of light irradiated onto the first ferromagnetic layer 1 increases, the magnetization M1 in the case of FIG. 8 tilts so as to be parallel to the magnetization M2 of the second ferromagnetic layer 2, while the magnetization M1 in the case of FIG. 9 tilts so as to be antiparallel to the magnetization M2 of the second ferromagnetic layer 2. The tilt direction of the magnetization M1 in FIGS. 8 and 9 is different because the direction of the spin transfer torque acting on the magnetization M1 is different.

[0083] When the intensity of light irradiated to the first ferromagnetic layer 1 increases, the resistance value of the magnetic element 10 decreases and the output voltage from the magnetic element 10 decreases in the case of Fig. 8. In the case of Fig. 9, the resistance value of the magnetic element 10 increases and the output voltage from the magnetic element 10 increases.

[0084] When the intensity of the light irradiated to the first ferromagnetic layer 1 returns to the first intensity, the state of the magnetization M1 of the first ferromagnetic layer 1 returns to its original state due to the effect of magnetic anisotropy on the magnetization M1, and as a result, the magnetic element 10 returns to its initial state.

[0085] Although the first ferromagnetic layer 1 is an in-plane magnetization film and the second ferromagnetic layer 2 is a perpendicular magnetization film, this relationship may be reversed. That is, in the initial state, the magnetization M1 may be oriented in the z direction, and the magnetization M2 may be oriented in any direction within the xy plane.

[0086] As described above, the light-detecting element 100 according to the first embodiment converts light irradiated onto the magnetic element 10 into an output voltage from the magnetic element 10, thereby converting the light into an electrical signal.

[0087] Furthermore, light L is irradiated onto the magnetic element 10 from the side surface 10s. That is, light L is also likely to be irradiated onto the portion of the first ferromagnetic layer 1 on the spacer layer 3 side. Changes in the magnetization state of the portion of the first ferromagnetic layer 1 on the spacer layer 3 side contribute significantly to changes in the output voltage from the magnetic element 10 (changes in the resistance value of the magnetic element 10 in the z direction). As a result, the responsiveness of changes in the output voltage from the magnetic element 10 (changes in the resistance value of the magnetic element 10) to changes in the state of light L is high.

[0088] Although the first embodiment has been described above in detail with reference to the drawings, the first embodiment is not limited to this example.

[0089] 10, the side surface 11s of the magnetic element 11 may be inclined with respect to the z direction. The side surface 11s is continuous with the side surface 21s of the first electrode 21 and the side surface 31s of the second electrode 31. The side surface 11s is a flat surface. The photodetector 101 according to the first modification example has the same effect as the photodetector element 100, since the portion of the first ferromagnetic layer 1 on the spacer layer side is also easily irradiated with light.

[0090] Furthermore, like the photodetector element 102 shown in FIG. 11 and the photodetector element 103 shown in FIG. 12, the magnetic elements 12 and 13 may have a shape other than a rectangle when viewed in the z direction.

[0091] 11 has a circular shape when viewed from the z direction. A portion of the side surface 12s of the magnetic element 12, the side surface 20s of the first electrode 20, and the side surface 30s of the second electrode 30 are in contact with the same imaginary plane VS. The side surface 12s is in contact with the imaginary plane VS at a linear portion extending in the z direction. The portion of the side surface 12s in contact with the imaginary plane VS is continuous with the side surface 20s and the side surface 30s.

[0092] The magnetic element 13 shown in Fig. 12 has a shape of a missing circle when viewed from the z direction. The side surfaces of the magnetic element 13 consist of a flat side surface 13s and an arc-shaped side surface when viewed from the z direction. The side surface 13s, the side surface 20s, and the side surface 30s are in contact with the same imaginary plane VS. The side surface 13s, the side surface 20s, and the side surface 30s are continuous with each other.

[0093] Furthermore, as in the case of a light-detecting element 104 shown in FIG. 13, the shape of the first electrode 22 and the second electrode 32 when viewed in the z direction may be other than rectangular.

[0094] The magnetic element 12 shown in FIG. 13 has a circular shape when viewed from the z direction. The first electrode 22 and the second electrode 32 shown in FIG. 13 have an elliptical shape when viewed from the z direction. A portion of the side surface 12s of the magnetic element 12, a portion of the side surface 22s of the first electrode 22, and a portion of the side surface 32s of the second electrode 32 are in contact with the same imaginary plane VS. The side surface 12s is in contact with the imaginary plane VS at its linear portion extending in the z direction. The side surface 22s is in contact with the imaginary plane VS at its linear portion extending in the z direction. The portion of the side surface 12s that is in contact with the imaginary plane VS is continuous with the portions of the side surfaces 22s and 32s that are in contact with the imaginary plane VS.

[0095] Although an example in which parts of the side surfaces of both the first electrode and the second electrode and parts of the side surfaces of the magnetic element are in contact with the same imaginary plane VS has been illustrated and described above, this is not limiting. For example, only parts of the side surfaces of one of the first electrode and the second electrode and parts of the side surfaces of the magnetic element may be in contact with the same imaginary plane VS.

[0096] "Second embodiment" 14 is a yz cross-sectional view of a photodetector 105 according to the second embodiment. The photodetector 105 differs from the photodetector 100 according to the first embodiment in that it has an oxide film 60. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0097] The oxide film 60 covers the flat surface consisting of the side surface 10s, the side surface 20s, and the side surface 30s. Although Fig. 14 shows an example in which the oxide film 60 covers the entire flat surface consisting of the side surface 10s, the side surface 20s, and the side surface 30s, it may be configured to cover only a part of it. For example, the oxide film 60 may be configured to cover only the side surface 10s of the magnetic element 10.

[0098] The oxide film 60 is transparent to the wavelength range of light irradiated onto the magnetic element 10. The oxide film 60 is, for example, an oxide having insulating properties. The oxide film 60 is, for example, silicon oxide, aluminum oxide, or the like. The oxide film 60 protects the side surface 10s of the magnetic element 10 from corrosion, wear, and the like.

[0099] The light-detecting element 105 according to the second embodiment has the same effects as the light-detecting element 100. Furthermore, by having the oxide film 60, the light-detecting element 105 has excellent weather resistance.

[0100] "Third embodiment" 15 is a yz cross-sectional view of a photodetector 106 according to the third embodiment. The photodetector 106 differs from the photodetector 100 according to the first embodiment in that it has a heat-generating portion 70. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0101] The heat generating portion 70 is located in a position where it can heat the first ferromagnetic layer 1. For example, the heat generating portion 70 is located behind the magnetic element 10 in the direction of light irradiation to the magnetic element 10. The heat generating portion 70 does not have to overlap with the magnetic element 10 when viewed from the light irradiation direction. The heat generating portion 70 is located on the opposite side of the magnetic element 10 from the surface of the magnetic element 10 that is mainly irradiated with light L.

[0102] The heat generating unit 70 is, for example, a coil. The heat generating unit 70 is, for example, a resistor made of Cu, a nickel-chromium alloy, an iron-chromium-aluminum alloy, etc. When a current flows through the resistor, the heat generating unit 70 generates heat.

[0103] When the heat generating portion 70 generates heat, the first ferromagnetic layer 1 is heated. The heated first ferromagnetic layer 1 expands. When the first ferromagnetic layer 1 expands, the side surface of the first ferromagnetic layer 1 protrudes from the imaginary plane connecting the side surface 20s and the side surface 30s.

[0104] The photodetector 106 according to the third embodiment has the same effect as the photodetector 100. Furthermore, the heat generated by the heat generating portion 70 can cause the side surface of the first ferromagnetic layer 1 to protrude from the virtual plane connecting the side surface 20s and the side surface 30s, thereby changing the distance between the side surface of the first ferromagnetic layer 1 and the light irradiating portion 40. As a result, the intensity of light irradiated to the first ferromagnetic layer 1 can be adjusted without changing the irradiation intensity from the light irradiating portion 40.

[0105] "Fourth embodiment" 16 is a yz cross-sectional view of a light-detecting element 107 according to the fourth embodiment. The light-detecting element 107 differs from the light-detecting element 100 according to the first embodiment in that it has a heat-generating portion 70 and an expansion portion 80. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0106] The heat generating section 70 is located in a position where it can heat the expansion section 80. The heat generating section 70 is located, for example, behind the magnetic element 10 in the direction of light irradiation to the magnetic element 10. The heat generating section 70 does not have to overlap with the magnetic element 10 when viewed from the light irradiation direction. The heat generating section 70 is located on the opposite side of the magnetic element 10 from the surface of the magnetic element 10 that is mainly irradiated with light L.

[0107] The expansion portion 80 is, for example, located behind the magnetic element 10 in the direction of light irradiation to the magnetic element 10. The expansion portion 80 does not have to overlap with the magnetic element 10 when viewed from the light irradiation direction. The expansion portion 80 is located on the opposite side of the magnetic element 10 from the surface of the magnetic element 10 that is mainly irradiated with light L. The expansion portion 80 is heated and expands when the heat-generating portion 70 generates heat. The expansion portion 80 is located in a position where it can push out the first ferromagnetic layer 1.

[0108] The expansion portion 80 is made of a material having a larger linear thermal expansion coefficient than the first ferromagnetic layer 1. The expansion portion 80 is made of, for example, aluminum, magnesium, zinc, tin, or an alloy containing any of these.

[0109] When the heat generating portion 70 generates heat, the expansion portion 80 is heated. When the heated expansion portion 80 expands, the first ferromagnetic layer 1 is pushed outward. As a result, the side surface of the first ferromagnetic layer 1 protrudes from the imaginary plane connecting the side surface 20s and the side surface 30s.

[0110] The photodetector 107 according to the fourth embodiment has the same effect as the photodetector 100. Furthermore, the heat generation of the heat generating portion 70 and the expansion of the expansion portion 80 can change the distance between the side surface of the first ferromagnetic layer 1 and the light irradiating portion 40. As a result, the intensity of the light irradiated to the first ferromagnetic layer 1 can be adjusted without changing the irradiation intensity from the light irradiating portion 40.

[0111] As described above, the present invention is not limited to the above-described embodiment and modifications, and various modifications and variations are possible within the scope of the gist of the present invention as set forth in the claims. For example, the characteristic features of the above-described embodiment and modifications may be combined.

[0112] The light-detecting elements according to the above-described embodiments and modifications can be applied to light sensor devices such as image sensors, transmitters and receivers in communication systems, and the like.

[0113] 17 is a block diagram of a transceiver 1000 according to the first application example. The transceiver 1000 includes a receiver 300 and a transmitter 400. The receiver 300 receives an optical signal L1, and the transmitter 400 transmits an optical signal L2.

[0114] The receiving device 300 includes, for example, a photodetector element 301 and a signal processing unit 302. The photodetector element 301 is any one of the photodetectors 100 to 107 according to the above-described embodiments or modifications. In the receiving device 300, the first ferromagnetic layer 1 is irradiated with light having a variable intensity, including a high-frequency optical signal L1. A lens may be disposed on the first ferromagnetic layer 1 side in the stacking direction of the photodetector element 301, so that light passing through the lens and condensed is irradiated onto the first ferromagnetic layer 1. The lens may be formed during a wafer process for forming the photodetector element 301. Alternatively, light passing through a waveguide may be irradiated onto the first ferromagnetic layer 1 of the photodetector element 301. The light irradiated onto the first ferromagnetic layer 1 of the photodetector element 301 is, for example, laser light. The photodetector element 301 converts the optical signal L1 into an electrical signal. The operation of the photodetector element 301 may be either a first operation example or a second operation example. The signal processing unit 302 processes the electrical signal converted by the photodetector element 301. The signal processing unit 302 receives the signal included in the optical signal L1 by processing the electrical signal generated by the photodetector element 301. The receiving device 300 receives the signal included in the optical signal L1 based on the output voltages from the magnetic elements 10-13.

[0115] The transmitting device 400 includes, for example, a light source 401, an electric signal generating element 402, and an optical modulation element 403. The light source 401 is, for example, a laser element. The light source 401 may be external to the transmitting device 400. The electric signal generating element 402 generates an electric signal based on transmission information. The electric signal generating element 402 may be integrated with a signal conversion element of the signal processing unit 302. The optical modulation element 403 modulates the light output from the light source 401 based on the electric signal generated by the electric signal generating element 402, and outputs an optical signal L2.

[0116] Fig. 18 is a conceptual diagram of an example of a communication system. The communication system shown in Fig. 18 has two terminal devices 500. The terminal devices 500 are, for example, smartphones, tablets, personal computers, or the like.

[0117] Each of the terminal devices 500 includes a receiving device 300 and a transmitting device 400. An optical signal transmitted from the transmitting device 400 of one terminal device 500 is received by the receiving device 300 of the other terminal device 500. The light used for transmission and reception between the terminal devices 500 is, for example, visible light. The receiving device 300 has the above-mentioned photodetecting elements 100 to 107 as the photodetecting element 301. The above-mentioned photodetecting elements 100 to 107 have good responsiveness to light, so the communication system shown in FIG. 18 is highly reliable.

[0118] 19 is a conceptual diagram of a cross section of an optical sensor device 2000 according to a second application example. The optical sensor device 2000 includes, for example, a circuit board 110, a wiring layer 120, and a plurality of optical sensors S. The wiring layer 120 and the plurality of optical sensors S are each formed on the circuit board 110.

[0119] Each of the multiple optical sensors S has, for example, a photodetector element 100, a wavelength filter F, and a lens R. While FIG. 19 shows an example in which the photodetector element 100 is used, photodetectors 101 to 107 may be used instead of the photodetector element 100. The photodetector element 100 is irradiated with light that has passed through the wavelength filter F. As described above, the photodetector element 100 converts the light irradiated onto the magnetic element 10 into an electrical signal. It is preferable that the photodetector element 100 operates in the second operation example.

[0120] The wavelength filter F selects light of a specific wavelength and transmits light of a specific wavelength range. The wavelength range of light transmitted by each wavelength filter F may be the same or different. For example, the optical sensor device 2000 may include an optical sensor S (hereinafter referred to as a blue sensor) having a wavelength filter F that transmits blue light (a wavelength range of 380 nm or more and less than 490 nm), an optical sensor S (hereinafter referred to as a green sensor) having a wavelength filter F that transmits green light (a wavelength range of 490 nm or more and less than 590 nm), and an optical sensor S (hereinafter referred to as a red sensor) having a wavelength filter F that transmits red light (a wavelength range of 590 nm or more and less than 800 nm). The blue sensor, the green sensor, and the red sensor form one pixel, and by arranging these pixels, the optical sensor device 2000 can be used as an image sensor.

[0121] The lens R focuses the light toward the magnetic element 10. In the optical sensor S shown in FIG. 19, one photodetector element 100 is arranged below one wavelength filter F, but multiple photodetector elements 100 may be arranged below one wavelength filter F.

[0122] The circuit board 110 has, for example, an analog-to-digital converter 111 and an output terminal 112. The electrical signal sent from the optical sensor S is converted into digital data by the analog-to-digital converter 111 and output from the output terminal 112.

[0123] The wiring layer 120 has a plurality of wirings 121. Interlayer insulating films 122 are present between the plurality of wirings 121. The wirings 121 electrically connect each of the optical sensors S to the circuit board 110 and between each of the arithmetic circuits formed on the circuit board 110. Each of the optical sensors S and the circuit board 110 are connected via, for example, through-wiring that penetrates the interlayer insulating film 122 in the z direction. Noise can be reduced by shortening the distance between the wirings between each of the optical sensors S and the circuit board 110.

[0124] The wiring 121 is conductive. The wiring 121 is made of, for example, Al, Cu, or the like. The interlayer insulating film 122 is an insulator that insulates between wirings in a multilayer wiring or between elements. The interlayer insulating film 122 is made of, for example, an oxide, nitride, or oxynitride of Si, Al, or Mg. The interlayer insulating film 122 is made of, for example, silicon oxide (SiO x ), silicon nitride (SiN x ), silicon carbide (SiC), chromium nitride, silicon carbonitride (SiCN), silicon oxynitride (SiON), aluminum oxide (Al2O3), zirconium oxide (ZrO x ) etc.

[0125] The optical sensor device 2000 described above can be used in, for example, a terminal device. FIG. 20 is a schematic diagram of an example of a terminal device 600. The left side of FIG. 20 is the front side of the terminal device 600, and the right side of FIG. 20 is the back side of the terminal device 600. The terminal device 600 has a camera CA. The optical sensor device 2000 described above can be used as an imaging element of this camera CA. In FIG. 20, a smartphone is shown as an example of the terminal device 600, but this is not limiting. The terminal device 600 can be, for example, a tablet, a personal computer, a digital camera, etc., in addition to a smartphone. [Explanation of symbols]

[0126] 1...first ferromagnetic layer, 2...second ferromagnetic layer, 3...spacer layer, 10, 11, 12, 13...magnetic element, 20, 21, 22...first electrode, 30, 31, 32...second electrode, 10s, 11s, 12s, 13s, 20s, 21s, 22s, 30s, 31s, 32s...side surface, 40...light-irradiated portion, 50...insulating layer, 60...oxide film, 70...heat-generating portion, 80...expansion portion, 100, 101, 102, 103, 104, 105, 106, 107...light-detecting element, 110 ...circuit board, 111...analog-digital converter, 112...output terminal, 120...wiring layer, 121...wiring, 122...interlayer insulating film, 300...receiving device, 301...photodetecting element, 302...signal processing unit, 400...transmitting device, 401...light source, 402...electrical signal generating element, 403...light modulation element, 500, 600...terminal device, 1000...transmitting / receiving device, 2000...optical sensor device, CA...camera, F...wavelength filter, R...lens, S...optical sensor

Claims

1. a magnetic element including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer; the first ferromagnetic layer is irradiated with light from a direction intersecting the stacking direction of the magnetic element; A light-sensing element, wherein an output voltage from the magnetic element changes in accordance with the intensity of light irradiated onto the first ferromagnetic layer.

2. 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, the first ferromagnetic layer is irradiated with light from a direction intersecting the stacking direction of the magnetic element; The magnetic element further includes a first electrode and a second electrode sandwiching the magnetic element in the stacking direction, a side surface of at least one of the first electrode and the second electrode and a side surface of the magnetic element are at least partially in contact with the same imaginary plane; The light detecting element is configured such that the first ferromagnetic layer is irradiated with the light from the imaginary plane side.

3. 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, the first ferromagnetic layer is irradiated with light from a direction intersecting the stacking direction of the magnetic element; a part of a side surface of the magnetic element is a flat surface, The light-sensing element is configured such that the light is irradiated onto the flat surface.

4. a part of a side surface of the magnetic element is a flat surface, The light-sensing element according to claim 2 , wherein the flat surface is in contact with the imaginary plane.

5. 5. The light-sensing element according to claim 3, further comprising an oxide film covering the flat surface and capable of transmitting light.

6. 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, the first ferromagnetic layer is irradiated with light from a direction intersecting the stacking direction of the magnetic element; Further having a heat generating portion, The heat generating portion is located behind the magnetic element in a light irradiation direction in which the light is mainly irradiated onto the magnetic element.

7. Further having an expansion portion, the heat generating portion is located at a position where it can heat the expansion portion, the expansion portion is located behind the magnetic element in a light irradiation direction in which the light is mainly irradiated onto the magnetic element, The light-detecting element according to claim 6 , wherein the expansion portion has a linear thermal expansion coefficient greater than that of the first ferromagnetic layer.

8. 8. The light-sensing element according to claim 1, wherein the light is light containing a light modulation signal and varying in intensity.

9. 8. The light-sensing element according to claim 1, wherein the light is light that has passed through a wavelength filter.

10. A receiving device comprising a photodetector element according to any one of claims 1 to 8.

11. An optical sensor device comprising the optical detection element according to any one of claims 1 to 7 and claim 9.

Images