Image sensor and image pickup device

Abstract

An image-capturing element according to an embodiment of the present disclosure is provided with: a first electrode; a second electrode disposed opposite to the first electrode; an organic layer which is provided between the first and second electrodes, and includes at least a photoelectric conversion layer; a first semiconductor layer which is provided between the second electrode and the organic layer, and includes at least one among a carbon-containing compound having greater electron affinity than the work function of the first electrode and an inorganic compound having a greater work function than that of the first electrode; and a second semiconductor layer which is provided between the second electrode and the first semiconductor layer, and, in which the absolute value B of the difference between a highest occupied molecular orbital (HOMO) level and a Fermi level of the second electrode is equal to or greater than the absolute value A of the difference between a first lowest unoccupied molecular orbital (LUMO) level calculated from an optical band gap and the Fermi level, or which has, near the Fermi level, an in-gap level of the density of states of 1 / 10000 or greater with respect to the HOMO level.

Description

[Technical field]

[0001] The present disclosure relates to an imaging element using, for example, an organic material, and an imaging device including the same. [Background technology]

[0002] In recent years, a so-called vertical spectroscopic imaging element has been proposed, which has a vertical multilayer structure in which an organic photoelectric conversion unit is disposed above a semiconductor substrate. In the vertical spectroscopic imaging element, light in the red and blue wavelength regions is photoelectrically converted by photoelectric conversion units (photodiodes PD1 and PD2) formed in the semiconductor substrate, respectively, and light in the green wavelength region is photoelectrically converted by an organic photoelectric conversion film provided in the organic photoelectric conversion unit.

[0003] In such an image sensor, the charges generated by photoelectric conversion in the photodiodes PD1 and PD2 are temporarily stored in the photodiodes PD1 and PD2, and then transferred to the respective floating diffusion layers. This allows the photodiodes PD1 and PD2 to be fully depleted. On the other hand, the charges generated in the organic photoelectric conversion section are directly stored in the floating diffusion layers, making it difficult to fully deplete the organic photoelectric conversion section, resulting in increased kTC noise and worsening random noise, resulting in a decrease in image quality.

[0004] In response to this, for example, Patent Document 1 discloses an imaging element in which a photoelectric conversion section is provided on a semiconductor substrate and is formed by stacking a first electrode, a photoelectric conversion layer, and a second electrode, and in which a charge storage electrode is disposed at a distance from the first electrode and faces the photoelectric conversion layer via an insulating layer, thereby suppressing degradation in image quality. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-157816 A Summary of the Invention

[0006] Incidentally, there is a demand for improved light response in image pickup devices.

[0007] It is desirable to provide an imaging element and an imaging device that can improve the light response.

[0008] An imaging element according to an embodiment of the present disclosure includes a first electrode, a second electrode disposed opposite the first electrode, an organic layer provided between the first electrode and the second electrode and including at least a photoelectric conversion layer, a first semiconductor layer provided between the second electrode and the organic layer and including at least one of a carbon-containing compound having an electron affinity greater than a work function of the first electrode and an inorganic compound having a work function greater than a work function of the first electrode, and a second semiconductor layer provided between the second electrode and the first semiconductor layer, the absolute value B of a difference between a HOMO (Highest Occupied Molecular Orbital) level and a Fermi level of the second electrode being equal to or greater than an absolute value A of a difference between a first LUMO (Lowest Unoccupied Molecular Orbital) level and the Fermi level calculated from an optical band gap, or a second semiconductor layer having an in-gap level near the Fermi level with a density of states equal to or greater than 1 / 10,000 of the HOMO level.

[0009] The imaging device according to an embodiment of the present disclosure includes one or more imaging elements according to the embodiment of the present disclosure for each of a plurality of pixels.

[0010] In the imaging element and imaging device according to an embodiment of the present disclosure, a first semiconductor layer containing at least one of a carbon-containing compound having an electron affinity larger than the work function of the first electrode and an inorganic compound having a work function larger than the work function of the first electrode is provided between a second electrode arranged opposite to the first electrode with an organic layer including at least a photoelectric conversion layer therebetween, and further, a second semiconductor layer is provided between the second electrode and the first semiconductor layer, in which the absolute value B of the difference between the HOMO level and the Fermi level of the second electrode is equal to or larger than the absolute value A of the difference between the first LUMO level and the Fermi level calculated from the optical band gap, or in which a gap level with a density of states equal to or larger than 1 / 10000 of the HOMO level is provided near the Fermi level. This promotes the injection of electrons from the second electrode to the first semiconductor layer. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a schematic configuration of an imaging element according to an embodiment of the present disclosure. [Diagram 2] 2 is an equivalent circuit diagram of the image sensor shown in FIG. 1. [Diagram 3] 2 is a schematic diagram showing the arrangement of a lower electrode of an organic photoelectric conversion unit and a transistor constituting a control unit shown in FIG. 1. [Figure 4A] FIG. 2 is a diagram illustrating an example of energy levels in the organic photoelectric conversion unit illustrated in FIG. [Figure 4B] 1. FIG. 4 is a diagram illustrating another example of the energy level in the organic photoelectric conversion unit shown in FIG. [Diagram 5] FIG. 1 shows the measurement results of each energy level of NBphen. [Figure 6] FIG. 1 shows the measurement results of each energy level of NDI35. [Figure 7] 2A to 2C are cross-sectional views for explaining a method of manufacturing the image sensor shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view showing a step following FIG. 7. [Figure 9] FIG. 9 is a cross-sectional view showing a step following FIG. 8. [Figure 10]FIG. 10 is a cross-sectional view showing a step following FIG. [Figure 11] FIG. 11 is a cross-sectional view showing a process following FIG. [Figure 12] FIG. 12 is a cross-sectional view showing a step following FIG. [Figure 13] 13 is a cross-sectional view showing a process following FIG. 12. [Figure 14] 2 is a timing chart illustrating an example of an operation of the image sensor illustrated in FIG. [Figure 15] 2 is a block diagram illustrating a configuration of an imaging device using the imaging element shown in FIG. 1 as a pixel. [Figure 16] 16 is a functional block diagram illustrating an example of an electronic device (camera) using the imaging device illustrated in FIG. 15. [Figure 17] 1 is a block diagram showing an example of a schematic configuration of an in-vivo information acquiring system. [Figure 18] 1 is a diagram illustrating an example of a schematic configuration of an endoscopic surgery system. [Figure 19] 2 is a block diagram showing an example of a functional configuration of a camera head and a CCU. FIG. [Figure 20] 1 is a block diagram showing an example of a schematic configuration of a vehicle control system; [Figure 21] 4 is an explanatory diagram showing an example of the installation positions of an outside-vehicle information detection unit and an imaging unit; FIG. [Figure 22] FIG. 2 is a schematic cross-sectional view showing a device structure as an evaluation sample. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following aspect. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each drawing. The order of description is as follows. 1. Embodiment (Example in which an electron injection promotion layer having a predetermined energy level is provided between a work function adjustment layer and an upper electrode) 1-1.Image sensor configuration 1-2. Manufacturing method of image sensor 1-3. Actions and Effects 2. Application Examples 3. Application Examples 4. Working Example

[0013] <1. Preferred embodiment> FIG. 1 shows a cross-sectional configuration of an imaging element (imaging element 10) according to an embodiment of the present disclosure. FIG. 2 is an equivalent circuit diagram of the imaging element 10 shown in FIG. 1. FIG. 3 is a schematic diagram showing the arrangement of transistors constituting the lower electrode 21 and the control unit of the imaging element 10 shown in FIG. 1. The imaging element 10 constitutes one pixel (unit pixel P) in an imaging device (imaging device 1; see FIG. 15) such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor used in electronic devices such as digital still cameras and video cameras. The imaging element 10 of this embodiment is an organic photoelectric conversion unit 20 provided on a semiconductor substrate 30, in which a work function adjustment layer 25 (first semiconductor layer) having a predetermined work function or electron affinity is provided between a photoelectric conversion layer 24 and an upper electrode 27 (second electrode), and an electron injection promotion layer 26 (second semiconductor layer) having a predetermined energy level is provided between the upper electrode 27 and the work function adjustment layer 25.

[0014] (1-1. Configuration of the image sensor) The imaging element 10 is, for example, a so-called vertical spectroscopic type in which one organic photoelectric conversion unit 20 and two inorganic photoelectric conversion units 32B and 32R are stacked in the vertical direction. The organic photoelectric conversion unit 20 is provided on the first surface (back surface) 30A side of the semiconductor substrate 30. The inorganic photoelectric conversion units 32B and 32R are embedded in the semiconductor substrate 30 and stacked in the thickness direction of the semiconductor substrate 30. The organic photoelectric conversion unit 20 has a photoelectric conversion layer 24 formed of an organic material between a lower electrode 21 (first electrode) and an upper electrode 27 arranged opposite to each other. The photoelectric conversion layer 24 is configured to include a p-type semiconductor and an n-type semiconductor, and has a bulk heterojunction structure in the layer. The bulk heterojunction structure is a p / n junction surface formed by mixing a p-type semiconductor and an n-type semiconductor.

[0015] The organic photoelectric conversion unit 20 and the inorganic photoelectric conversion units 32B and 32R selectively detect light in different wavelength ranges and perform photoelectric conversion. Specifically, the organic photoelectric conversion unit 20 acquires, for example, a green (G) color signal. The inorganic photoelectric conversion units 32B and 32R acquire, for example, blue (B) and red (R) color signals, respectively, due to differences in absorption coefficients. This allows the image sensor 10 to acquire multiple types of color signals in one pixel without using a color filter.

[0016] In this embodiment, the case where electrons among electron-hole pairs (excitons) generated by photoelectric conversion are read out as signal charges, that is, the case where an n-type semiconductor region is used as a photoelectric conversion layer will be described. In addition, in the figure, the "+ (plus)" attached to "p" and "n" indicates that the p-type or n-type impurity concentration is high.

[0017] On the second surface (front surface) 30B of the semiconductor substrate 30, for example, floating diffusions FD1 (region 36B in the semiconductor substrate 30), FD2 (region 37C in the semiconductor substrate 30), FD3 (region 38C in the semiconductor substrate 30), transfer transistors Tr2 and Tr3, an amplifier transistor (modulation element) AMP, a reset transistor RST, a selection transistor SEL, and a multilayer wiring layer 40 are provided. The multilayer wiring layer 40 has a configuration in which wiring layers 41, 42, and 43 are stacked in an insulating layer 44, for example.

[0018] In the drawings, the first surface 30A side of the semiconductor substrate 30 is represented as a light incident side S1, and the second surface 30B side is represented as a wiring layer side S2.

[0019] The organic photoelectric conversion section 20 has a configuration in which a lower electrode 21, a charge storage layer 23, a photoelectric conversion layer 24, a work function adjustment layer 25, an electron injection promotion layer 26, and an upper electrode 27 are laminated in this order from the first surface 30A side of the semiconductor substrate 30. In addition, an insulating layer 22 is provided between the lower electrode 21 and the charge storage layer 23. The lower electrode 21 is formed separately for each imaging element 10, and is composed of a read electrode 21A and a storage electrode 21B separated from each other by the insulating layer 22, as will be described in detail later. Of the lower electrode 21, the read electrode 21A is electrically connected to the photoelectric conversion layer 24 through an opening 22H provided in the insulating layer 22. In FIG. 1, an example in which the charge storage layer 23, the photoelectric conversion layer 24, the work function adjustment layer 25, and the upper electrode 27 are formed separately for each imaging element 10 is shown, but they may be provided as a continuous layer common to a plurality of imaging elements 10, for example.

[0020] Between the first surface 30A of the semiconductor substrate 30 and the lower electrode 21, for example, an insulating layer 28 and an interlayer insulating layer 29 are provided. The insulating layer 28 is composed of a layer (fixed charge layer) 28A having a fixed charge and a dielectric layer 28B having insulating properties. A protective layer 51 is provided on the upper electrode 27. In the protective layer 51, for example, a light-shielding film 52 is provided on the readout electrode 21A. This light-shielding film 52 may be provided so as to cover at least the region of the readout electrode 21A that is in direct contact with the photoelectric conversion layer 24, without covering at least the storage electrode 21B. Optical members such as a planarization layer (not shown) and an on-chip lens 53 are provided above the protective layer 51.

[0021] A through electrode 34 is provided between the first surface 30A and the second surface 30B of the semiconductor substrate 30. The organic photoelectric conversion unit 20 is connected to a gate Gamp of the amplifier transistor AMP provided on the second surface 30B side of the semiconductor substrate 30 and one source / drain region 36B of a reset transistor RST (reset transistor Tr1rst) also serving as a floating diffusion FD1 via the through electrode 34. This allows the image sensor 10 to effectively transfer charges (here, electrons) generated in the organic photoelectric conversion unit 20 on the first surface 30A side of the semiconductor substrate 30 to the second surface 30B side of the semiconductor substrate 30 via the through electrode 34, thereby improving characteristics.

[0022] The lower end of the through electrode 34 is connected to a connection portion 41A in the wiring layer 41, and the connection portion 41A and the gate Gamp of the amplifier transistor AMP are connected via a lower first contact 45. The connection portion 41A and the floating diffusion FD1 (region 36B) are connected, for example, via a lower second contact 46. The upper end of the through electrode 34 is connected to the readout electrode 21A, for example, via a pad portion 39A and an upper first contact 39C.

[0023] The through electrode 34 is provided, for example, for each organic photoelectric conversion unit 20 in each imaging element 10. The through electrode 34 functions as a connector between the organic photoelectric conversion unit 20 and the gate Gamp of the amplifier transistor AMP and the floating diffusion FD1, and also serves as a transmission path for charges generated in the organic photoelectric conversion unit 20.

[0024] A reset gate Grst of the reset transistor RST is disposed next to the floating diffusion FD1 (one of the source / drain regions 36B of the reset transistor RST). This makes it possible to reset the charge stored in the floating diffusion FD1 by the reset transistor RST.

[0025] In the imaging element 10 of the present embodiment, light incident on the organic photoelectric conversion section 20 from the upper electrode 27 side is absorbed by the photoelectric conversion layer 24. The excitons generated by this move to the interface between the electron donor and electron acceptor constituting the photoelectric conversion layer 24, and are dissociated into excitons, that is, into electrons and holes. The charges (electrons and holes) generated here are carried to different electrodes by diffusion due to the difference in carrier concentration and an internal electric field due to the difference in work function between the anode (here, the upper electrode 27) and the cathode (here, the lower electrode 21), and are detected as a photocurrent. In addition, the transport direction of the electrons and holes can be controlled by applying a potential between the lower electrode 21 and the upper electrode 27.

[0026] The structure and materials of each part will be described below.

[0027] The organic photoelectric conversion section 20 is an organic photoelectric conversion element that absorbs green light corresponding to a selective wavelength range, for example, a part or all of the wavelength range of 450 nm or more and 650 nm or less, and generates excitons.

[0028] As described above, the lower electrode 21 is composed of the read electrode 21A and the storage electrode 21B which are formed separately. The read electrode 21A is for transferring the charge (here, electrons) generated in the photoelectric conversion layer 24 to the floating diffusion FD1, and is connected to the floating diffusion FD1 via, for example, the upper first contact 39C, the pad portion 39A, the through electrode 34, the connection portion 41A, and the lower second contact 46. The storage electrode 21B is for storing electrons as signal charges in the charge storage layer 23 among the charges generated in the photoelectric conversion layer 24. The storage electrode 21B is provided in a region that directly faces the light receiving surfaces of the inorganic photoelectric conversion units 32B and 32R formed in the semiconductor substrate 30 and covers these light receiving surfaces. The storage electrode 21B is preferably larger than the read electrode 21A, and thus can store a large amount of charge.

[0029] The lower electrode 21 is made of a conductive film having optical transparency, and is made of, for example, ITO (indium tin oxide). However, as a constituent material of the lower electrode 21, in addition to ITO, a tin oxide (SnO2)-based material with a dopant added, or a zinc oxide-based material made of zinc oxide (ZnO) with a dopant added may be used. Examples of the zinc oxide-based material include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, and indium zinc oxide (IZO) with indium (In) added. In addition to these, CuI, InSbO4, ZnMgO, CuInO2, MgIN2O4, CdO, or ZnSnO3 may also be used.

[0030] The charge storage layer 23 is provided below the photoelectric conversion layer 24, specifically between the insulating layer 22 and the photoelectric conversion layer 24, and is for storing signal charges generated in the photoelectric conversion layer 24. In this embodiment, since electrons are used as signal charges, the charge storage layer 23 is preferably formed using an n-type semiconductor material, and for example, a material having an energy level in which the lowest end of the conduction band is shallower than the work function of the lower electrode 21 is preferably used. Examples of such n-type semiconductor materials include IGZO (In-Ga-Zn-O-based oxide semiconductor), ZTO (Zn-Sn-O-based oxide semiconductor), IGZTO (In-Ga-Zn-Sn-O-based oxide semiconductor), GTO (Ga-Sn-O-based oxide semiconductor), and IGO (In-Ga-O-based oxide semiconductor). The charge storage layer 23 is preferably formed using at least one of the above oxide semiconductor materials, and IGZO is preferably used among them. The thickness of the charge storage layer 23 is, for example, 30 nm to 200 nm, and preferably 60 nm to 150 nm. By providing the charge storage layer 23 made of the above material under the photoelectric conversion layer 24, it is possible to prevent recombination of charges during charge storage and improve transfer efficiency.

[0031] The photoelectric conversion layer 24 is for converting light energy into electrical energy. The photoelectric conversion layer 24 is configured to include, for example, two or more organic materials (p-type semiconductor materials or n-type semiconductor materials) that function as p-type semiconductors or n-type semiconductors, respectively. The photoelectric conversion layer 24 has a junction surface (p / n junction surface) between the p-type semiconductor material and the n-type semiconductor material within the layer. The p-type semiconductor functions relatively as an electron donor (donor), and the n-type semiconductor functions relatively as an electron acceptor (acceptor). The photoelectric conversion layer 24 provides a place where excitons generated when light is absorbed are separated into electrons and holes. Specifically, the excitons are separated into electrons and holes at the interface (p / n junction surface) between the electron donor and the electron acceptor.

[0032] In addition to the p-type semiconductor material and the n-type semiconductor material, the photoelectric conversion layer 24 may contain an organic material that converts light in a predetermined wavelength range into electric current while transmitting light in other wavelength ranges, that is, a so-called dye material. When the photoelectric conversion layer 24 is formed using three types of organic materials, the p-type semiconductor material, the n-type semiconductor material, and the dye material, it is preferable that the p-type semiconductor material and the n-type semiconductor material are materials that have optical transparency in the visible range (e.g., 450 nm or more and 800 nm or less). The thickness of the photoelectric conversion layer 24 is, for example, 50 nm or more and 500 nm or less.

[0033] The photoelectric conversion layer 24 of this embodiment preferably contains an organic material and has absorption between visible light and near infrared light. Examples of organic materials constituting the photoelectric conversion layer 24 include quinacridone, chlorinated boron subphthalocyanine, pentacene, benzothienobenzothiophene, fullerene, and derivatives thereof. The photoelectric conversion layer 24 is composed of a combination of two or more of the above organic materials. The above organic materials function as p-type semiconductors or n-type semiconductors depending on the combination.

[0034] The organic material constituting the photoelectric conversion layer 24 is not particularly limited. In addition to the above organic materials, for example, any one of naphthalene, anthracene, phenanthrene, tetracene, pyrene, perylene, and fluoranthene or their derivatives is preferably used. Alternatively, polymers such as phenylenevinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, and diacetylene, or their derivatives may be used. In addition, metal complex dyes, cyanine dyes, merocyanine dyes, phenylxanthene dyes, triphenylmethane dyes, rhodacyanine dyes, xanthene dyes, macrocyclic azaannulene dyes, azulene dyes, naphthoquinone, anthraquinone dyes, condensed polycyclic aromatics such as anthracene and pyrene, and chain compounds in which aromatic rings or heterocyclic compounds are condensed, or two nitrogen-containing heterocycles such as quinoline, benzothiazole, and benzoxazole having a squarylium group and a croconite methine group as a binding chain, or cyanine-like dyes bonded by a squarylium group and a croconite methine group, etc. can be preferably used. Note that, as the above-mentioned metal complex dyes, dithiol metal complex dyes, metal phthalocyanine dyes, metal porphyrin dyes, or ruthenium complex dyes are preferred, but are not limited thereto.

[0035] The work function adjustment layer 25 is provided on the photoelectric conversion layer 24, and is intended to change the internal electric field in the photoelectric conversion layer 24 to quickly transfer and accumulate the signal charges generated in the photoelectric conversion layer 24 to the charge storage layer 23. The work function adjustment layer 25 is optically transparent, and preferably has a light absorption rate of 10% or less for visible light, for example. The work function adjustment layer 25 can be formed using a carbon-containing compound having an electron affinity larger than the work function of the charge storage layer 23. The electron affinity corresponds to the difference between the LUMO level (LUMO2) calculated from the optical band gap described later and the vacuum level.

[0036] Examples of materials constituting the work function adjustment layer 25 include tetracyanoquinodimethane derivatives such as 2,3,5,6-tetrafluoro-tetracyanoquinodimethane (F4-TCNQ), 2,3,5-trifluoro-tetracyanoquinodimethane (F3-TCNQ), 2,5-difluoro-tetracyanoquinodimethane (F2-TCNQ), 2-fluoro-tetracyanoquinodimethane (F1-TCNQ), 2-trifluoromethyl-tetracyanoquinodimethane (CF3-TCNQ) and 1,3,4,5,7,8-hexafluoro-tetracyanonaphthoquinodimethane (F6-TCNQ), 1,4,5,8,9,12-hexaazatripheny Hexaazatriphenylene derivatives such as 2,3,6,7,10,11-hexacarbonitrile (HATCN), hexaazatrinaphthylene derivatives such as 2,3,8,9,14,15-hexachloro-5,6,11,12,17,18-hexaazatrinaphthylene (HATNA-Cl6) and 2,3,8,9,14,15-hexafluoro-5,6,11,12,17,18-hexaazatrinaphthylene (HATNA-F6), phthalocyanine derivatives such as 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-copper phthalocyanine (F16-CuPc), and C 60 F 36 Or C 60 F 48fluorinated fullerenes such as fluorinated fullerenes. Alternatively, the work function adjustment layer 25 can be formed using an inorganic compound having a work function larger than that of the lower electrode 21 (particularly, the storage electrode 21B). Examples of such materials include transition metal oxides such as molybdenum oxide (MoO3), tungsten oxide (WO3), vanadium oxide (VO5), and rhenium oxide (ReO3), as well as salts such as copper iodide (CuI), antimony chloride (SbCl5), iron oxide (FeCl3), and sodium chloride (NaCl). The work function adjustment layer 25 may be formed as a single layer film using the above carbon-containing compound or inorganic compound alone, or may be formed as a laminated film of a layer containing a carbon compound and a layer containing an inorganic compound. In that case, it is preferable to laminate the carbon-containing compound film / inorganic compound film in this order, taking into consideration damage caused by annealing treatment when forming the upper electrode 27. The thickness of the work function adjustment layer 25 is, for example, 0.5 nm or more and 30 nm or less.

[0037] The electron injection promotion layer 26 is provided between the work function adjustment layer 25 and the upper electrode 27, and is intended to promote the injection of electrons from the upper electrode 27. In the image sensor 10 in which electrons are read out as signal charges from the readout electrode 21A as in the present embodiment, holes generated in the photoelectric conversion layer 24 are recombined with electrons injected from the upper electrode 27 at the interface between the work function adjustment layer 25 and the organic layer including the photoelectric conversion layer 24 adjacent to the work function adjustment layer 25. This recombination allows electrons (signal charges) to be efficiently read out from the readout electrode 21A. The recombination of holes and electrons at the interface between the work function adjustment layer 25 and the organic layer including the photoelectric conversion layer 24 adjacent to the work function adjustment layer 25 depends on the charge densities of the holes and electrons. The injection of electrons from the upper electrode 27 to the work function adjustment layer 25 is promoted by making the electron injection promotion layer 26 have an energy level, for example, as shown in FIG. 4A or FIG. 4B.

[0038] For example, the electron injection promotion layer 26 preferably has an absolute value B of the difference between the HOMO (Highest Occupied Molecular Orbital) level and the Fermi level of the upper electrode 27 that is equal to or greater than the absolute value A of the difference between the LUMO (Lowest Unoccupied Molecular Orbital) level (LUMO2, corresponding to the first LUMO level) calculated from the optical band gap and the Fermi level of the upper electrode 27 (1). Specifically, for example, the absolute value B of the difference between the HOMO level and the Fermi level of the upper electrode 27 is preferably 1.5 times or more the absolute value A of the difference between the LUMO2 and the Fermi level of the upper electrode 27. Furthermore, the electron injection promotion layer 26 preferably has an absolute value B of the difference between the HOMO level and the Fermi level of the upper electrode 27 that is greater than the absolute value A' of the difference between the LUMO level (LUMO1) and the Fermi level of the upper electrode 27 (2).

[0039] Alternatively, the electron injection promotion layer 26 preferably has an in-gap level with a density of states equal to or greater than 1 / 10000 of the HOMO level near the Fermi level of the upper electrode 27 (3). More specifically, for example, the absolute value b of the difference between the HOMO level and the in-gap level of the electron injection promotion layer 26 is preferably equal to or greater than twice the absolute value a of the difference between the LUMO level (LUMO2) calculated from the optical band gap and the in-gap level (4). Alternatively, the absolute value b of the difference between the HOMO level and the in-gap level of the electron injection promotion layer 26 is preferably equal to or greater than 1.5 times the absolute value a' of the difference between the LUMO level (LUMO1) and the in-gap level (5).

[0040] The HOMO level and LUMO level (LUMO2) were obtained by ultraviolet photoelectron spectroscopy (UPS) and ultraviolet-visible spectroscopy, respectively, and the LUMO level (LUMO1) was obtained by low-energy inverse photoemission spectroscopy (LEIPS). The difference between LUMO1 and LUMO2 corresponds to the exciton binding energy.

[0041] Examples of materials constituting the electron injection promotion layer 26 include [2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline] (NBphen), naphthalene diimide molecules (e.g., NDI35), and lithium fluoride (LiF). FIG. 5 shows an analysis of each energy level of NBphen by high-sensitivity ultraviolet photoemission spectroscopy (HS-UPS). NBphen satisfies the above (1), (3), and (4). Even when the exciton binding energy is taken into account, it satisfies the above (1), (2), and (5). FIG. 6 shows an analysis of each energy level of NDI35 by UPS and low-energy inverse photoemission spectroscopy (LEIPS). NDI35 satisfies all of the above (1) to (5). The thickness of the electron injection promotion layer 26 is, for example, 0.5 nm or more and 10 nm or less.

[0042] Other organic layers may be provided between the photoelectric conversion layer 24 and the lower electrode 21 (for example, between the charge storage layer 23 and the photoelectric conversion layer 24) and between the photoelectric conversion layer 24 and the upper electrode 27 (for example, between the photoelectric conversion layer 24 and the work function adjustment layer 25). Specifically, for example, the charge storage layer 23, the hole blocking layer, the photoelectric conversion layer 24, the electron blocking layer, the work function adjustment layer 25, and the electron injection promotion layer 26 may be laminated in this order from the lower electrode 21 side. Furthermore, an undercoat layer and a hole transport layer may be provided between the lower electrode 21 and the photoelectric conversion layer 24, and a buffer layer may be provided between the photoelectric conversion layer 24 and the upper electrode 27. In addition, when a buffer layer is provided between the photoelectric conversion layer 24 and the upper electrode 27, for example adjacent to the electron injection promotion layer 26, it is preferable that the buffer layer has an energy level shallower than the work function of the work function adjustment layer 25. Moreover, the buffer layer is preferably formed using an organic material having a glass transition point higher than, for example, 100°C.

[0043] The upper electrode 27 is made of a conductive film having optical transparency, similar to the lower electrode 21. In an imaging device 1 using the imaging element 10 as one pixel, the upper electrode 27 may be separated for each pixel, or may be formed as an electrode common to each pixel. The upper electrode 27 has a work function smaller than that of the work function adjustment layer 25, for example. The thickness of the upper electrode 27 is, for example, 10 nm to 200 nm.

[0044] The fixed charge layer 28A may be a film having a positive fixed charge or a film having a negative fixed charge. Examples of materials for the film having a negative fixed charge include hafnium oxide, aluminum oxide, zirconium oxide, tantalum oxide, and titanium oxide. Examples of materials other than those mentioned above include lanthanum oxide, praseodymium oxide, cerium oxide, neodymium oxide, promethium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, thulium oxide, ytterbium oxide, lutetium oxide, yttrium oxide, aluminum nitride film, hafnium oxynitride film, and aluminum oxynitride film.

[0045] The fixed charge layer 28A may have a structure in which two or more types of films are laminated together, which can further enhance the function as a hole accumulation layer, for example, in the case of a film having a negative fixed charge.

[0046] The material of the dielectric layer 28B is not particularly limited, but it is formed of, for example, a silicon oxide film, a TEOS film, a silicon nitride film, a silicon oxynitride film, or the like.

[0047] The interlayer insulating layer 29 is formed, for example, of a single layer film made of one of silicon oxide, silicon nitride, silicon oxynitride (SiON), etc., or a laminated film made of two or more of these materials.

[0048] The insulating layer 22 serves to electrically separate the storage electrode 21B from the charge storage layer 23. The insulating layer 22 is provided, for example, on the interlayer insulating layer 29 so as to cover the lower electrode 21. As described above, the insulating layer 22 has an opening 22H provided on the read electrode 21A, and the read electrode 21A and the charge storage layer 23 are electrically connected through the opening 22H. The insulating layer 22 can be formed, for example, using the same material as the interlayer insulating layer 29, and is, for example, a single layer film made of one of silicon oxide, silicon nitride, silicon oxynitride (SiON), etc., or a laminated film made of two or more of these. The insulating layer 22 has a thickness of, for example, 20 nm to 500 nm.

[0049] The semiconductor substrate 30 is, for example, made of an n-type silicon (Si) substrate, and has a p-well 31 in a predetermined region. The above-mentioned transfer transistors Tr2 and Tr3, amplifier transistor AMP, reset transistor RST, selection transistor SEL, etc. are provided on a second surface 30B of the p-well 31. In addition, a peripheral circuit section 130 (see, for example, FIG. 15) made up of a logic circuit, etc. is provided on the periphery of the semiconductor substrate 30.

[0050] The reset transistor RST (reset transistor Tr1rst) resets the charge transferred from the organic photoelectric conversion unit 20 to the floating diffusion FD1, and is composed of, for example, a MOS transistor. Specifically, the reset transistor Tr1rst is composed of a reset gate Grst, a channel formation region 36A, and source / drain regions 36B, 36C. The reset gate Grst is connected to a reset line RST1, and one source / drain region 36B of the reset transistor Tr1rst also serves as the floating diffusion FD1. The other source / drain region 36C constituting the reset transistor Tr1rst is connected to a power supply line VDD.

[0051] The amplifier transistor AMP is a modulation element that modulates the amount of charge generated in the organic photoelectric conversion unit 20 into a voltage, and is composed of, for example, a MOS transistor. Specifically, the amplifier transistor AMP is composed of a gate Gamp, a channel formation region 35A, and source / drain regions 35B, 35C. The gate Gamp is connected to the readout electrode 21A and one of the source / drain regions 36B (floating diffusion FD1) of the reset transistor Tr1rst via the lower first contact 45, the connection portion 41A, the lower second contact 46, the through electrode 34, etc. In addition, one of the source / drain regions 35B shares an area with the other of the source / drain regions 36C constituting the reset transistor Tr1rst, and is connected to the power supply line VDD.

[0052] The selection transistor SEL (selection transistor TR1sel) is composed of a gate Gsel, a channel formation region 34A, and source / drain regions 34B and 34C. The gate Gsel is connected to a selection line SEL1. One source / drain region 34B shares an area with the other source / drain region 35C constituting the amplifier transistor AMP, and the other source / drain region 34C is connected to a signal line (data output line) VSL1.

[0053] The inorganic photoelectric conversion units 32B and 32R each have a pn junction in a predetermined region of the semiconductor substrate 30. The inorganic photoelectric conversion units 32B and 32R are capable of splitting light in the vertical direction by utilizing the fact that the wavelength of light absorbed varies depending on the depth of incidence of light in a silicon substrate. The inorganic photoelectric conversion unit 32B selectively detects, for example, blue light and accumulates a signal charge corresponding to blue, and is disposed at a depth capable of efficiently photoelectrically converting blue light. The inorganic photoelectric conversion unit 32R selectively detects, for example, red light and accumulates a signal charge corresponding to red, and is disposed at a depth capable of efficiently photoelectrically converting red light. Note that blue (B) is a color corresponding to, for example, a wavelength range of 450 nm to 495 nm, and red (R) is a color corresponding to, for example, a wavelength range of 620 nm to 750 nm. Each of the inorganic photoelectric conversion units 32B and 32R may be capable of detecting light in a part or all of the wavelength ranges.

[0054] The inorganic photoelectric conversion unit 32B includes, for example, a p+ region that serves as a hole accumulation layer and an n region that serves as an electron accumulation layer. The inorganic photoelectric conversion unit 32R has, for example, a p+ region that serves as a hole accumulation layer and an n region that serves as an electron accumulation layer (having a pnp stacked structure). The n region of the inorganic photoelectric conversion unit 32B is connected to a vertical transfer transistor Tr2. The p+ region of the inorganic photoelectric conversion unit 32B is bent along the transfer transistor Tr2 and connected to the p+ region of the inorganic photoelectric conversion unit 32R.

[0055] The transfer transistor Tr2 (transfer transistor TR2trs) is for transferring the signal charge (here, electrons) corresponding to blue, which is generated and accumulated in the inorganic photoelectric conversion unit 32B, to the floating diffusion FD2. Since the inorganic photoelectric conversion unit 32B is formed at a deep position from the second surface 30B of the semiconductor substrate 30, it is preferable that the transfer transistor TR2trs of the inorganic photoelectric conversion unit 32B is composed of a vertical transistor. In addition, the transfer transistor TR2trs is connected to a transfer gate line TG2. Furthermore, a floating diffusion FD2 is provided in the region 37C near the gate Gtrs2 of the transfer transistor TR2trs. The charge accumulated in the inorganic photoelectric conversion unit 32B is read out to the floating diffusion FD2 via a transfer channel formed along the gate Gtrs2.

[0056] The transfer transistor Tr3 (transfer transistor TR3trs) transfers the signal charge (here, electrons) corresponding to red that is generated and accumulated in the inorganic photoelectric conversion unit 32R to the floating diffusion FD3, and is configured by, for example, a MOS transistor. The transfer transistor TR3trs is also connected to a transfer gate line TG3. Furthermore, a floating diffusion FD3 is provided in a region 38C in the vicinity of the gate Gtrs3 of the transfer transistor TR3trs. The charge accumulated in the inorganic photoelectric conversion unit 32R is read out to the floating diffusion FD3 via a transfer channel formed along the gate Gtrs3.

[0057] Further, a reset transistor TR2rst, an amplifier transistor TR2amp, and a selection transistor TR2sel constituting a control unit of the inorganic photoelectric conversion unit 32B are provided on the second surface 30B side of the semiconductor substrate 30. Further, a reset transistor TR3rst, an amplifier transistor TR3amp, and a selection transistor TR3sel constituting a control unit of the inorganic photoelectric conversion unit 32R are provided.

[0058] The reset transistor TR2rst is composed of a gate, a channel forming region, and a source / drain region. The gate of the reset transistor TR2rst is connected to a reset line RST2, and one of the source / drain regions of the reset transistor TR2rst is connected to a power supply line VDD. The other source / drain region of the reset transistor TR2rst also serves as a floating diffusion FD2.

[0059] The amplifier transistor TR2amp is composed of a gate, a channel forming region, and a source / drain region. The gate is connected to the other source / drain region (floating diffusion FD2) of the reset transistor TR2rst. In addition, one of the source / drain regions constituting the amplifier transistor TR2amp shares an area with one of the source / drain regions constituting the reset transistor TR2rst, and is connected to the power supply line VDD.

[0060] The selection transistor TR2sel is composed of a gate, a channel formation region, and a source / drain region. The gate is connected to a selection line SEL2. One of the source / drain regions constituting the selection transistor TR2sel shares the region with the other of the source / drain regions constituting the amplifier transistor TR2amp. The other of the source / drain regions constituting the selection transistor TR2sel is connected to a signal line (data output line) VSL2.

[0061] The reset transistor TR3rst is composed of a gate, a channel forming region, and a source / drain region. The gate of the reset transistor TR3rst is connected to a reset line RST3, and one of the source / drain regions constituting the reset transistor TR3rst is connected to a power supply line VDD. The other source / drain region constituting the reset transistor TR3rst also serves as a floating diffusion FD3.

[0062] The amplifier transistor TR3amp is composed of a gate, a channel forming region, and a source / drain region. The gate is connected to the other source / drain region (floating diffusion FD3) constituting the reset transistor TR3rst. In addition, one of the source / drain regions constituting the amplifier transistor TR3amp shares an area with one of the source / drain regions constituting the reset transistor TR3rst, and is connected to the power supply line VDD.

[0063] The selection transistor TR3sel is composed of a gate, a channel formation region, and a source / drain region. The gate is connected to a selection line SEL3. One of the source / drain regions constituting the selection transistor TR3sel shares the same region with the other of the source / drain regions constituting the amplifier transistor TR3amp. The other of the source / drain regions constituting the selection transistor TR3sel is connected to a signal line (data output line) VSL3.

[0064] The reset lines RST1, RST2, and RST3, the selection lines SEL1, SEL2, and SEL3, and the transfer gate lines TG2 and TG3 are each connected to a vertical drive circuit 112 that constitutes a drive circuit. The signal lines (data output lines) VSL1, VSL2, and VSL3 are connected to a column signal processing circuit 113 that constitutes a drive circuit.

[0065] The lower first contact 45, the lower second contact 46, the upper first contact 39C and the upper second contact 39D are made of, for example, a doped silicon material such as PDAS (Phosphorus Doped Amorphous Silicon) or a metal material such as aluminum (Al), tungsten (W), titanium (Ti), cobalt (Co), hafnium (Hf) or tantalum (Ta).

[0066] The protective layer 51 is provided above the organic photoelectric conversion section 20 and is made of a material having optical transparency. Specifically, the protective layer 51 is made of, for example, a single layer film made of any one of silicon oxide, silicon nitride, silicon oxynitride, etc., or a laminated film made of two or more of them. The thickness of this protective layer 51 is, for example, 100 nm to 30,000 nm.

[0067] The light-shielding film 52 is provided in the protective layer 51 so as to cover, for example, the readout electrode 21A. Examples of the material of the light-shielding film 52 include tungsten (W), titanium (Ti), titanium nitride (TiN), and aluminum (Al), and the light-shielding film 52 is configured as, for example, a laminated film of W / TiN / Ti or a single layer film of W. The thickness of the light-shielding film 52 is, for example, 50 nm or more and 400 nm or less.

[0068] In the pixel section 1a on the protective layer 51, for example, an on-chip lens 53 is provided for each unit pixel P. The on-chip lens 53 focuses incident light onto the light receiving surfaces of the organic photoelectric conversion section 20, the inorganic photoelectric conversion section 32B, and the inorganic photoelectric conversion section 32R.

[0069] (1-2. Manufacturing method of image sensor) The imaging element 10 of the present embodiment can be manufactured, for example, as follows.

[0070] 7 to 13 show the process sequence of a manufacturing method of the image sensor 10. First, as shown in Fig. 7, a first conductivity type well, for example, a p-well 31, is formed in a semiconductor substrate 30, and inorganic photoelectric conversion units 32B, 32R of a second conductivity type (for example, n-type) are formed in this p-well 31. A p+ region is formed in the vicinity of the first surface 30A of the semiconductor substrate 30.

[0071] 7, n+ regions that become floating diffusions FD1 to FD3 are formed on the second surface 30B of the semiconductor substrate 30, and then a gate insulating layer 33 and a gate wiring layer 47 including the gates of the transfer transistor Tr2, the transfer transistor Tr3, the selection transistor SEL, the amplifier transistor AMP, and the reset transistor RST are formed. This forms the transfer transistor Tr2, the transfer transistor Tr3, the selection transistor SEL, the amplifier transistor AMP, and the reset transistor RST. Furthermore, a multilayer wiring layer 40 consisting of wiring layers 41 to 43 including a lower first contact 45, a lower second contact 46, and a connection portion 41A and an insulating layer 44 is formed on the second surface 30B of the semiconductor substrate 30.

[0072] The base of the semiconductor substrate 30 is, for example, an SOI (Silicon on Insulator) substrate in which the semiconductor substrate 30, a buried oxide film (not shown), and a holding substrate (not shown) are laminated. Although not shown in Fig. 7, the buried oxide film and the holding substrate are bonded to the first surface 30A of the semiconductor substrate 30. After the ion implantation, an annealing process is performed.

[0073] Next, a support substrate (not shown) or another semiconductor base is bonded to the second surface 30B side (the multilayer wiring layer 40 side) of the semiconductor substrate 30, and the substrate is turned upside down. Next, the semiconductor substrate 30 is separated from the buried oxide film of the SOI substrate and the holding substrate, and the first surface 30A of the semiconductor substrate 30 is exposed. The above steps can be performed by techniques used in normal CMOS processes, such as ion implantation and CVD (Chemical Vapor Deposition).

[0074] Next, as shown in Fig. 8, the semiconductor substrate 30 is processed from the first surface 30A side by, for example, dry etching to form, for example, a ring-shaped opening 34H. As shown in Fig. 8, the depth of the opening 34H penetrates from the first surface 30A to the second surface 30B of the semiconductor substrate 30 and reaches, for example, the connection portion 41A.

[0075] Next, for example, a negative fixed charge layer 28A is formed on the first surface 30A of the semiconductor substrate 30 and the side surface of the opening 34H. Two or more types of films may be laminated as the negative fixed charge layer 28A. This makes it possible to further enhance the function as a hole accumulation layer. After forming the negative fixed charge layer 28A, a dielectric layer 28B is formed. Next, pad portions 39A, 39B are formed at predetermined positions on the dielectric layer 28B, and then an interlayer insulating layer 29 is formed on the dielectric layer 28B and the pad portions 39A, 39B, and the surface of the interlayer insulating layer 29 is planarized using a chemical mechanical polishing (CMP) method.

[0076] Subsequently, as shown in FIG. 9, openings 29H1 and 29H2 are formed on the pad portions 39A and 39B, respectively, and then a conductive material such as Al is filled into the openings 29H1 and 29H2 to form an upper first contact 39C and an upper second contact 39D.

[0077] 10, a conductive film 21x is formed on the interlayer insulating layer 29, and then a photoresist PR is formed at a predetermined position of the conductive film 21x. Then, the read electrode 21A and the storage electrode 21B shown in FIG. 11 are patterned by etching and removing the photoresist PR.

[0078] Subsequently, as shown in FIG. 12, an insulating layer 22 is formed on the interlayer insulating layer 29, the read electrode 21A, and the storage electrode 21B, and then an opening 22H is provided on the read electrode 21A.

[0079] Next, as shown in FIG. 13, the charge storage layer 23, the photoelectric conversion layer 24, the work function adjustment layer 25, the electron injection promotion layer 26, and the upper electrode 27 are formed on the insulating layer 22. When the charge storage layer 23, the work function adjustment layer 25, and the electron injection promotion layer 26 are formed using an organic material, it is desirable to form the charge storage layer 23, the photoelectric conversion layer 24, and the work function adjustment layer 25 continuously in a vacuum process (in a vacuum integrated process). In addition, the method of forming the photoelectric conversion layer 24 is not necessarily limited to a method using a vacuum deposition method, and other methods, such as a spin coating technique or a printing technique, may be used. Finally, a protective layer 51 including a light-shielding film 52 and an on-chip lens 53 are formed above the organic photoelectric conversion unit 20. The above steps complete the imaging element 10 shown in FIG. 1.

[0080] In the imaging element 10, when light is incident on the organic photoelectric conversion unit 20 through the on-chip lens 53, the light passes through the organic photoelectric conversion unit 20 and the inorganic photoelectric conversion units 32B and 32R in this order, and is photoelectrically converted into green, blue, and red light during the passage. The operation of acquiring signals of each color will be described below.

[0081] (Acquisition of a green signal by the organic photoelectric conversion unit 20) Of the light incident on the imaging element 10, green light is first selectively detected (absorbed) by the organic photoelectric conversion section 20 and photoelectrically converted.

[0082] The organic photoelectric conversion unit 20 is connected to the gate Gamp of the amplifier transistor AMP and the floating diffusion FD1 via the through electrode 34. Thus, the electrons of the electron-hole pairs generated in the organic photoelectric conversion unit 20 are extracted from the lower electrode 21 side, transferred to the second surface 30B side of the semiconductor substrate 30 via the through electrode 34, and accumulated in the floating diffusion FD1. At the same time, the amount of charge generated in the organic photoelectric conversion unit 20 is modulated into a voltage by the amplifier transistor AMP.

[0083] In addition, a reset gate Grst of the reset transistor RST is disposed next to the floating diffusion FD1, so that the charge accumulated in the floating diffusion FD1 is reset by the reset transistor RST.

[0084] Here, the organic photoelectric conversion unit 20 is connected not only to the amplifier transistor AMP but also to the floating diffusion FD1 via the through electrode 34, so that the charge accumulated in the floating diffusion FD1 can be easily reset by the reset transistor RST.

[0085] On the other hand, if the through electrode 34 and the floating diffusion FD1 are not connected, it becomes difficult to reset the charge accumulated in the floating diffusion FD1, and a large voltage is applied to pull it out to the upper electrode 27 side. This may damage the photoelectric conversion layer 24. In addition, a structure that allows resetting in a short time leads to an increase in dark noise, which is a trade-off, making this structure difficult to implement.

[0086] 14 shows an example of the operation of the image sensor 10. (A) shows the potential at the storage electrode 21B, (B) shows the potential at the floating diffusion FD1 (readout electrode 21A), and (C) shows the potential at the gate (Gsel) of the reset transistor TR1rst. In the image sensor 10, voltages are applied to the readout electrode 21A and the storage electrode 21B individually.

[0087] In the imaging element 10, during the accumulation period, a potential V1 is applied to the readout electrode 21A from the drive circuit, and a potential V2 is applied to the accumulation electrode 21B. Here, the potentials V1 and V2 are set such that V2 > V1. As a result, the charges (here, electrons) generated by photoelectric conversion are attracted to the accumulation electrode 21B and accumulated in the region of the charge accumulation layer 23 facing the accumulation electrode 21B (accumulation period). Incidentally, the potential of the region of the charge accumulation layer 23 facing the accumulation electrode 21B becomes a more negative value as the time of photoelectric conversion elapses. Note that holes are sent from the upper electrode 27 to the drive circuit.

[0088] In the imaging element 10, a reset operation is performed in the latter stage of the accumulation period. Specifically, at timing t1, the scanning unit changes the voltage of the reset signal RST from a low level to a high level. As a result, in the unit pixel P, the reset transistor TR1rst is turned on, and the voltage of the floating diffusion FD1 is set to the power supply line VDD, and the voltage of the floating diffusion FD1 is reset (reset period).

[0089] After the completion of the reset operation, the charge is read out. Specifically, at timing t2, a potential V3 is applied to the readout electrode 21A from the drive circuit, and a potential V4 is applied to the accumulation electrode 21B. Here, the potentials V3 and V4 are set such that V3 < V4. As a result, the charges (here, electrons) accumulated in the region corresponding to the accumulation electrode 21B are read out from the readout electrode 21A to the floating diffusion FD1. That is, the charges accumulated in the charge accumulation layer 23 are read out to the control unit (transfer period).

[0090] After the completion of the readout operation, again, a potential V1 is applied to the readout electrode 21A from the drive circuit, and a potential V2 is applied to the accumulation electrode 21B. As a result, the charges (here, electrons) generated by photoelectric conversion are attracted to the accumulation electrode 21B and accumulated in the region of the photoelectric conversion layer 24 facing the accumulation electrode 21B (accumulation period).

[0091] (Acquisition of blue and red signals by inorganic photoelectric conversion units 32B and 32R) Next, of the light transmitted through the organic photoelectric conversion section 20, the blue light is absorbed in the inorganic photoelectric conversion section 32B, and the red light is absorbed in the inorganic photoelectric conversion section 32R, in that order, and photoelectrically converted. In the inorganic photoelectric conversion section 32B, electrons corresponding to the incident blue light are accumulated in the n-region of the inorganic photoelectric conversion section 32B, and the accumulated electrons are transferred to the floating diffusion FD2 by the transfer transistor Tr2. Similarly, in the inorganic photoelectric conversion section 32R, electrons corresponding to the incident red light are accumulated in the n-region of the inorganic photoelectric conversion section 32R, and the accumulated electrons are transferred to the floating diffusion FD3 by the transfer transistor Tr3.

[0092] (1-3. Actions and Effects) In the imaging element 10 of the present embodiment, a work function adjustment layer 25 containing at least one of a carbon-containing compound having an electron affinity larger than the work function of the lower electrode 21 and an inorganic compound having a work function larger than the work function of the lower electrode 21 and an electron injection promotion layer 26 having a predetermined energy level are laminated in this order from the photoelectric conversion layer 24 side between the photoelectric conversion layer 24 and the upper electrode 27. The electron injection promotion layer 26 has an energy level in which the absolute value B of the difference between the HOMO level and the Fermi level of the upper electrode 27 is equal to or greater than the absolute value A of the difference between the LUMO level (LUMO2) calculated from the optical band gap and the Fermi level. Alternatively, the electron injection promotion layer 26 has an in-gap level with a density of states equal to or greater than 1 / 10000 of the HOMO level in the vicinity of the Fermi level of the upper electrode 27. This promotes the injection of electrons from the upper electrode 27 to the work function adjustment layer 25. This will be described below.

[0093] In an imaging device that extracts B / G / R signals separately from one pixel, as described above, the charges generated in the semiconductor substrate are temporarily stored in each photoelectric conversion unit (photodiodes PD1, PD2) formed in the semiconductor substrate, and then transferred to the corresponding floating diffusion FD. Therefore, each photoelectric conversion unit can be completely depleted. On the other hand, the charges photoelectrically converted in the organic photoelectric conversion unit arranged, for example, on the upper side of the semiconductor substrate are directly stored in the floating diffusion FD provided in the semiconductor substrate via a vertical transfer path provided in the semiconductor substrate. Therefore, it is difficult to completely deplete the photoelectric conversion layer, and as a result, the kTC noise increases, the random noise deteriorates, and the image quality decreases.

[0094] As a method for solving this problem, an imaging element has been devised in which a charge storage electrode is disposed apart from one electrode (e.g., a lower electrode) of a pair of electrodes disposed opposite to each other across a photoelectric conversion layer, and faces the photoelectric conversion layer via an insulating layer. In this imaging element, charges generated in the photoelectric conversion layer are stored in an area facing the charge storage electrode in the photoelectric conversion layer. The stored charges are transferred to the charge readout electrode side as appropriate and read out. This makes it possible to completely deplete the charge storage section at the start of exposure, suppressing kTC noise and improving image quality. In addition, in such an imaging element, a semiconductor layer using a metal oxide that is an n-type semiconductor such as IGZO is provided below the photoelectric conversion layer, thereby preventing recombination of charges during charge storage and further improving the transfer efficiency of the stored charges to the charge readout electrode.

[0095] However, when a metal oxide, which is an n-type semiconductor, is used for the semiconductor layer, a problem arises in how to quickly transfer and accumulate the electrons generated in the photoelectric conversion layer by light irradiation in the semiconductor layer. This problem can be solved by improving the light response of the photoelectric conversion layer.

[0096] In contrast, in this embodiment, an electron injection promotion layer 26 having the following energy level after bonding with the upper electrode 27 is provided between the work function adjustment layer 25 provided on the photoelectric conversion layer 24 and the upper electrode 27. When the electron injection promotion layer 26 is bonded to the upper electrode 27, the HOMO level and the LUMO level shift in the deeper direction according to the Fermi level of the upper electrode 27, and the Fermi level of the upper electrode 27 and the LUMO level of the electron injection promotion layer 26 become closer in energy to each other. Specifically, in this embodiment, the absolute value B of the difference between the HOMO level and the Fermi level of the upper electrode 27 is equal to or greater than the absolute value A of the difference between the LUMO level (LUMO2) calculated from the optical band gap and the Fermi level, or the electron injection promotion layer 26 having an in-gap level with a density of states equal to or greater than 1 / 10000 of the HOMO level is provided near the Fermi level. This promotes the injection of electrons injected from the upper electrode 27. That is, the carrier density of electrons at the interface between the work function adjustment layer 25 and the organic layer including the photoelectric conversion layer 24 adjacent to the work function adjustment layer 25 is improved.

[0097] As a result, in the imaging element 10 of the present embodiment, recombination of holes and potential is promoted at the interface between the work function adjustment layer 25 and the organic layer including the photoelectric conversion layer 24 adjacent to the work function adjustment layer 25. This makes it possible to improve the photoresponsiveness of the photoelectric conversion layer 24.

[0098] <2. Application Examples> (Application example 1) 15 shows the overall configuration of an imaging device (imaging device 1) in which the imaging element 10 described in the above embodiment is used for each pixel. The imaging device 1 is a CMOS image sensor, and has a pixel section 1a as an imaging area on a semiconductor substrate 30, and also has a peripheral circuit section 130 including, for example, a row scanning section 131, a horizontal selection section 133, a column scanning section 134, and a system control section 132 in the peripheral region of the pixel section 1a.

[0099] The pixel section 1a has, for example, a plurality of unit pixels P (corresponding to the image sensor 10) arranged two-dimensionally in a matrix. In the unit pixels P, for example, a pixel drive line Lread (specifically, a row selection line and a reset control line) is wired for each pixel row, and a vertical signal line Lsig is wired for each pixel column. The pixel drive line Lread transmits a drive signal for reading out a signal from the pixel. One end of the pixel drive line Lread is connected to an output terminal of the row scanning section 131 corresponding to each row.

[0100] The row scanning unit 131 is a pixel driving unit that is configured with a shift register, an address decoder, etc., and drives each unit pixel P of the pixel unit 1a, for example, row by row. A signal output from each unit pixel P of a pixel row selected and scanned by the row scanning unit 131 is supplied to the horizontal selection unit 133 through each vertical signal line Lsig. The horizontal selection unit 133 is configured with an amplifier, a horizontal selection switch, etc., provided for each vertical signal line Lsig.

[0101] The column scanning unit 134 is composed of a shift register, an address decoder, etc., and sequentially drives while scanning each horizontal selection switch of the horizontal selection unit 133. By the selective scanning by this column scanning unit 134, the signals of each pixel transmitted through each vertical signal line Lsig are output in sequence to the horizontal signal line 135, and transmitted to the outside of the semiconductor substrate 30 through the horizontal signal line 135.

[0102] A circuit portion consisting of row scanning section 131, horizontal selection section 133, column scanning section 134, and horizontal signal line 135 may be formed directly on semiconductor substrate 30, or may be disposed in an external control IC. Moreover, these circuit portions may be formed on another substrate connected by a cable or the like.

[0103] The system control unit 132 receives a clock and data instructing an operation mode provided from outside the semiconductor substrate 30, and also outputs data such as internal information of the imaging device 1. The system control unit 132 further has a timing generator that generates various timing signals, and performs drive control of peripheral circuits such as the row scanning unit 131, horizontal selection unit 133, and column scanning unit 134 based on the various timing signals generated by the timing generator.

[0104] (Application example 2) The imaging device 1 can be applied to any type of electronic device with an imaging function, such as a camera system such as a digital still camera or video camera, or a mobile phone with an imaging function. Fig. 16 shows a schematic configuration of an electronic device 2 (camera) as an example. The electronic device 2 is, for example, a video camera capable of taking still or moving images, and includes the imaging device 1, an optical system (optical lens) 310, a shutter device 311, a drive unit 313 that drives the imaging device 1 and the shutter device 311, and a signal processing unit 312.

[0105] The optical system 310 guides image light (incident light) from a subject to the pixel section 1a of the imaging device 1. This optical system 310 may be composed of a plurality of optical lenses. The shutter device 311 controls the light irradiation period and the light blocking period of the imaging device 1. The drive section 313 controls the transfer operation of the imaging device 1 and the shutter operation of the shutter device 311. The signal processing section 312 performs various signal processing on the signal output from the imaging device 1. The video signal Dout after the signal processing is stored in a storage medium such as a memory, or is output to a monitor, etc.

[0106] Furthermore, the imaging device 1 can be applied to the following electronic devices (a capsule endoscope 10100 and a moving object such as a vehicle).

[0107] <3. Application Examples> (Application example to an in-body information acquisition system) Furthermore, the technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

[0108] FIG. 17 is a block diagram showing an example of a schematic configuration of a patient's in-vivo information acquisition system using a capsule endoscope to which the technology according to the present disclosure (the present technology) can be applied.

[0109] The in-vivo information acquisition system 10001 includes a capsule endoscope 10100 and an external control device 10200 .

[0110] The capsule endoscope 10100 is swallowed by a patient during an examination. The capsule endoscope 10100 has an imaging function and a wireless communication function, and while moving inside an organ such as the stomach or intestines by peristalsis or the like until it is naturally discharged from the patient, sequentially captures images of the inside of the organ (hereinafter also referred to as in-vivo images) at predetermined intervals, and sequentially wirelessly transmits information about the in-vivo images to an external control device 10200 outside the body.

[0111] The external control device 10200 comprehensively controls the operation of the in-vivo information acquisition system 10001. In addition, the external control device 10200 receives information about the in-vivo image transmitted from the capsule endoscope 10100, and generates image data for displaying the in-vivo image on a display device (not shown) based on the received information about the in-vivo image.

[0112] In this manner, the in-vivo information acquiring system 10001 can obtain in-vivo images capturing images of the state inside the patient's body at any time from when the capsule endoscope 10100 is swallowed to when it is expelled.

[0113] The configurations and functions of the capsule endoscope 10100 and the external control device 10200 will be described in more detail.

[0114] The capsule endoscope 10100 has a capsule-shaped housing 10101, which houses a light source unit 10111, an imaging unit 10112, an image processing unit 10113, a wireless communication unit 10114, a power supply unit 10115, a power supply unit 10116, and a control unit 10117.

[0115] The light source unit 10111 is composed of a light source such as an LED (light emitting diode), and irradiates the imaging field of the imaging unit 10112 with light.

[0116] The imaging unit 10112 is composed of an imaging element and an optical system consisting of multiple lenses provided in front of the imaging element. Reflected light (hereinafter referred to as observation light) of light irradiated onto the body tissue to be observed is collected by the optical system and enters the imaging element. In the imaging unit 10112, the imaging element photoelectrically converts the observation light incident thereon, and generates an image signal corresponding to the observation light. The image signal generated by the imaging unit 10112 is provided to an image processing unit 10113.

[0117] The image processing unit 10113 is configured with a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), and performs various signal processing on the image signal generated by the imaging unit 10112. The image processing unit 10113 provides the image signal after the signal processing to the wireless communication unit 10114 as RAW data.

[0118] The wireless communication unit 10114 performs predetermined processing such as modulation processing on the image signal that has been subjected to signal processing by the image processing unit 10113, and transmits the image signal to the external control device 10200 via the antenna 10114A. The wireless communication unit 10114 also receives a control signal related to drive control of the capsule endoscope 10100 from the external control device 10200 via the antenna 10114A. The wireless communication unit 10114 provides the control signal received from the external control device 10200 to the control unit 10117.

[0119] The power supply unit 10115 is composed of an antenna coil for receiving power, a power regeneration circuit for regenerating power from a current generated in the antenna coil, a boost circuit, etc. In the power supply unit 10115, power is generated using the principle of so-called non-contact charging.

[0120] The power supply unit 10116 is composed of a secondary battery, and stores the power generated by the power supply unit 10115. In order to avoid cluttering the drawing, arrows and other symbols indicating the destination of the power supply from the power supply unit 10116 are omitted in Fig. 17, but the power stored in the power supply unit 10116 is supplied to the light source unit 10111, the imaging unit 10112, the image processing unit 10113, the wireless communication unit 10114, and the control unit 10117 and can be used to drive these units.

[0121] The control unit 10117 is composed of a processor such as a CPU, and appropriately controls the driving of the light source unit 10111, the imaging unit 10112, the image processing unit 10113, the wireless communication unit 10114, and the power supply unit 10115 in accordance with control signals transmitted from the external control device 10200.

[0122] The external control device 10200 is composed of a processor such as a CPU or a GPU, or a microcomputer or a control board in which a processor and a storage element such as a memory are mixed. The external control device 10200 controls the operation of the capsule endoscope 10100 by transmitting a control signal to the control unit 10117 of the capsule endoscope 10100 via the antenna 10200A. In the capsule endoscope 10100, for example, the light irradiation conditions for the observation target in the light source unit 10111 can be changed by the control signal from the external control device 10200. Furthermore, the imaging conditions (for example, the frame rate and exposure value in the imaging unit 10112) can be changed by the control signal from the external control device 10200. Furthermore, the content of the processing in the image processing unit 10113 and the conditions for the wireless communication unit 10114 to transmit an image signal (for example, the transmission interval, the number of transmitted images, etc.) may be changed by the control signal from the external control device 10200.

[0123] The external control device 10200 also applies various image processing to the image signal transmitted from the capsule endoscope 10100 to generate image data for displaying the captured in-vivo image on a display device. As the image processing, various signal processing such as development processing (demosaic processing), image quality improvement processing (band enhancement processing, super-resolution processing, NR (Noise reduction) processing, and / or image stabilization processing, etc.) and / or enlargement processing (electronic zoom processing) can be performed. The external control device 10200 controls the driving of the display device to display the captured in-vivo image based on the generated image data. Alternatively, the external control device 10200 may record the generated image data in a recording device (not shown) or print out the image data on a printing device (not shown).

[0124] An example of an in-vivo information acquisition system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to, for example, the imaging unit 10112 of the above-described configuration. This improves detection accuracy.

[0125] (Application example to endoscopic surgery system) The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

[0126] FIG. 18 is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (the present technology) can be applied.

[0127] 18 shows a state in which an operator (doctor) 11131 is performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 is composed of an endoscope 11100, other surgical tools 11110 such as an insufflation tube 11111 and an energy treatment tool 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are mounted.

[0128] The endoscope 11100 is composed of a lens barrel 11101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 11132, and a camera head 11102 connected to the base end of the lens barrel 11101. In the illustrated example, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may be configured as a so-called flexible scope having a flexible lens barrel.

[0129] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101, and is irradiated via the objective lens toward an observation target in the body cavity of the patient 11132. The endoscope 11100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0130] An optical system and an image sensor are provided inside the camera head 11102, and reflected light (observation light) from an observation target is collected on the image sensor by the optical system. The observation light is photoelectrically converted by the image sensor to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to an observation image. The image signal is transmitted to a camera control unit (CCU) 11201 as RAW data.

[0131] The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and performs overall control of the operations of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives an image signal from the camera head 11102, and performs various types of image processing on the image signal, such as development processing (demosaic processing), for displaying an image based on the image signal.

[0132] Under the control of the CCU 11201, the display device 11202 displays an image based on an image signal that has been subjected to image processing by the CCU 11201.

[0133] The light source device 11203 is composed of a light source such as an LED (light emitting diode), and supplies the endoscope 11100 with irradiation light when photographing an operation site or the like.

[0134] The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of irradiated light, magnification, focal length, etc.) of the endoscope 11100.

[0135] The treatment tool control device 11205 controls the driving of the energy treatment tool 11112 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 11206 sends gas into the body cavity of the patient 11132 via the insufflation tube 11111 to inflate the body cavity for the purpose of securing the field of view of the endoscope 11100 and securing the working space of the surgeon. The recorder 11207 is a device capable of recording various information related to the surgery. The printer 11208 is a device capable of printing various information related to the surgery in various formats such as text, image, or graph.

[0136] The light source device 11203 that supplies irradiation light to the endoscope 11100 when photographing the surgical site can be composed of a white light source composed of, for example, an LED, a laser light source, or a combination of these. When the white light source is composed of a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so that the white balance of the captured image can be adjusted in the light source device 11203. In this case, it is also possible to capture images corresponding to each of the RGB colors in a time-division manner by irradiating the observation object with laser light from each of the RGB laser light sources in a time-division manner and controlling the driving of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter to the image sensor.

[0137] The light source device 11203 may be controlled to change the intensity of the light it outputs at predetermined time intervals. The driving of the image sensor of the camera head 11102 may be controlled in synchronization with the timing of the change in the light intensity to obtain images in a time-division manner, and the images may be synthesized to generate an image with a high dynamic range that is free of so-called blackout and whiteout.

[0138] The light source device 11203 may be configured to supply light of a predetermined wavelength band corresponding to the special light observation. In the special light observation, for example, by utilizing the wavelength dependency of light absorption in body tissue, a narrow band light is irradiated compared to the irradiated light (i.e., white light) during normal observation, and a predetermined tissue such as blood vessels on the mucous membrane surface is photographed with high contrast, so-called narrow band imaging is performed. Alternatively, in the special light observation, a fluorescent observation may be performed in which an image is obtained by fluorescence generated by irradiating an excitation light. In the fluorescent observation, it is possible to irradiate an excitation light to a body tissue and observe the fluorescence from the body tissue (autofluorescence observation), or to locally inject a reagent such as indocyanine green (ICG) into the body tissue and irradiate the body tissue with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 11203 may be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0139] FIG. 19 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG.

[0140] The camera head 11102 has a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 has a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other by a transmission cable 11400 so as to be able to communicate with each other.

[0141] The lens unit 11401 is an optical system provided at the connection portion with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is configured by combining a plurality of lenses including a zoom lens and a focus lens.

[0142] The imaging unit 11402 may include one imaging element (so-called single-plate type) or multiple imaging elements (so-called multiple-plate type). When the imaging unit 11402 is configured as a multiple-plate type, for example, each imaging element may generate an image signal corresponding to each of RGB, and a color image may be obtained by combining the image signals. Alternatively, the imaging unit 11402 may be configured to have a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to a 3D (dimensional) display. By performing a 3D display, the surgeon 11131 can more accurately grasp the depth of the biological tissue in the surgical site. Note that when the imaging unit 11402 is configured as a multiple-plate type, the lens unit 11401 may also be provided in multiple systems corresponding to each imaging element.

[0143] Furthermore, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101, immediately behind the objective lens.

[0144] The driving unit 11403 is configured by an actuator, and moves the zoom lens and focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera head control unit 11405. This allows the magnification and focus of the image captured by the imaging unit 11402 to be appropriately adjusted.

[0145] The communication unit 11404 is configured by a communication device for transmitting and receiving various information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 to the CCU 11201 via the transmission cable 11400 as RAW data.

[0146] Furthermore, the communication unit 11404 receives a control signal for controlling the driving of the camera head 11102 from the CCU 11201, and supplies the control signal to the camera head control unit 11405. The control signal includes information on the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value at the time of capturing the image, and / or information specifying the magnification and focus of the captured image.

[0147] The image capturing conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by a user, or may be automatically set by the control unit 11413 of the CCU 11201 based on an acquired image signal. In the latter case, the endoscope 11100 is equipped with a so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

[0148] The camera head control unit 11405 controls the driving of the camera head 11102 based on a control signal received from the CCU 11201 via the communication unit 11404.

[0149] The communication unit 11411 is configured with a communication device for transmitting and receiving various information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

[0150] Furthermore, the communication unit 11411 transmits, to the camera head 11102, a control signal for controlling the driving of the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, or the like.

[0151] The image processing unit 11412 performs various types of image processing on the image signal, which is RAW data sent from the camera head 11102 .

[0152] The control unit 11413 performs various controls related to imaging of the surgical site etc. by the endoscope 11100 and display of the captured image obtained by imaging the surgical site etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

[0153] Further, the control unit 11413 causes the display device 11202 to display the captured image showing the surgical site, etc., based on the image signal that has been image-processed by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition techniques. For example, the control unit 11413 can recognize surgical tools such as forceps, specific living body parts, bleeding, mist when the energy treatment tool 11112 is used, etc., by detecting the shape and color of the edge of an object included in the captured image. When the control unit 11413 causes the display device 11202 to display the captured image, it may use the recognition result to superimpose various types of surgery support information on the image of the surgical site. By superimposing and presenting the surgery support information to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

[0154] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for communication of electrical signals, an optical fiber for optical communication, or a composite cable of these.

[0155] Here, in the illustrated example, communication is performed wired using a transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

[0156] An example of an endoscopic surgery system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to the imaging unit 11402 among the configurations described above. By applying the technology according to the present disclosure to the imaging unit 11402, detection accuracy is improved.

[0157] Although an endoscopic surgery system has been described as an example here, the technology disclosed herein may also be applied to other systems, such as a microsurgery system.

[0158] (Example of application to moving objects) The technology according to the present disclosure can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, a personal mobility device, an airplane, a drone, a ship, a robot, a construction machine, an agricultural machine (tractor), etc.

[0159] FIG. 20 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a moving object control system to which the technology according to the present disclosure can be applied.

[0160] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 20, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also, as functional configurations of the integrated control unit 12050, a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053 are illustrated.

[0161] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0162] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as head lamps, back lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves or signals of various switches transmitted from a portable device that replaces a key may be input to the body system control unit 12020. The body system control unit 12020 receives the input of these radio waves or signals and controls the door lock device, power window device, lamps, and the like of the vehicle.

[0163] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture an image outside the vehicle and receives the captured image. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for a person, a car, an obstacle, a sign, or characters on a road surface, based on the received image.

[0164] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal according to the amount of light received. The imaging unit 12031 can output the electrical signal as an image, or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0165] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing.

[0166] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, the steering mechanism, or the braking device based on the information inside and outside the vehicle acquired by the outside-of-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output a control command to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0167] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on the driver's operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle acquired by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0168] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside-vehicle information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside-vehicle information detection unit 12030, and perform cooperative control for the purpose of preventing glare, such as switching from high beams to low beams.

[0169] The audio / video output unit 12052 transmits at least one output signal of audio and image to an output device capable of visually or audibly notifying information to passengers in the vehicle or the outside of the vehicle. In the example of Fig. 20, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as the output device. The display unit 12062 may include at least one of an on-board display and a head-up display, for example.

[0170] FIG. 21 is a diagram showing an example of the installation position of the imaging unit 12031.

[0171] In FIG. 21, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0172] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided at positions such as the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided at the front nose and the imaging unit 12105 provided at the upper part of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided at the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided at the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided at the upper part of the windshield inside the vehicle cabin is mainly used to detect a preceding vehicle, a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.

[0173] 21 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, an overhead image of the vehicle 12100 viewed from above is obtained by superimposing the image data captured by the imaging units 12101 to 12104.

[0174] At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera made up of a plurality of imaging elements, or may be an imaging element having pixels for detecting a phase difference.

[0175] For example, the microcomputer 12051 can extract, as a preceding vehicle, a three-dimensional object that is the closest three-dimensional object on the travel path of the vehicle 12100 and travels at a predetermined speed (for example, 0 km / h or more) in approximately the same direction as the vehicle 12100, by calculating the distance to each three-dimensional object in the imaging ranges 12111 to 12114 and the change over time of this distance (relative speed with respect to the vehicle 12100) based on the distance information obtained from the imaging units 12101 to 12104. Furthermore, the microcomputer 12051 can set a vehicle distance to be secured in advance in front of the preceding vehicle, and perform automatic brake control (including follow-up stop control) and automatic acceleration control (including follow-up start control). In this way, cooperative control can be performed for the purpose of automatic driving that travels autonomously without relying on the driver's operation.

[0176] For example, the microcomputer 12051 classifies and extracts three-dimensional object data on three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. Then, the microcomputer 12051 determines a collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0177] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether or not a pedestrian is present in the captured images of the imaging units 12101 to 12104. The recognition of such a pedestrian is performed, for example, by a procedure of extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras, and a procedure of performing pattern matching processing on a series of feature points that indicate the contour of an object to determine whether or not the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating a pedestrian at a desired position.

[0178] <4. Examples> Next, examples of the present disclosure will be described in detail. In the following, an imaging element having a cross-sectional configuration shown in Fig. 22 was fabricated as a device sample, and its device characteristics were evaluated.

[0179] (Experimental Example 1) A 100 nm thick ITO film was formed on a quartz substrate using a sputtering device. This ITO film was patterned by photolithography and etching to form an ITO electrode (lower electrode 21). Next, the quartz substrate with the ITO electrode was cleaned by UV / ozone treatment, and then the quartz substrate was transferred to a vacuum deposition machine and 1×10 -5 While the pressure was reduced to below 1 Pa, the substrate holder was rotated to sequentially stack organic layers on the quartz substrate. First, a hole blocking layer 24A was formed on the lower electrode 21 at a substrate temperature of 0°C to a thickness of 10 nm using NDI-35 shown in the following formula (1). Next, F6-OPh-26F2 shown in the following formula (2), BP-rBDT shown in the following formula (3), and fullerene C 60At a substrate temperature of 40° C., the mixed layer was deposited at deposition rates of 0.50 Å / sec, 0.50 Å / sec, and 0.25 Å / sec, respectively, so that the thickness of the mixed layer was 230 nm, forming a photoelectric conversion layer 24. Next, PC-ID shown in the following formula (4) was deposited at a substrate temperature of 0° C. to a thickness of 10 nm to form an electron blocking layer 24B, and then HATCN shown in the following formula (5) was deposited at a thickness of 10 nm to form a work function adjustment layer 25. Next, NDI-35 shown in the following formula (1) was deposited at a thickness of 2 nm to form an electron injection promotion layer 26. Finally, the quartz substrate was transferred to a sputtering device, and an ITO film was deposited at a thickness of 50 nm on the electron injection promotion layer 26 to form an upper electrode 27. A sample (Experimental Example 1) having a photoelectric conversion area of ​​1 mm×1 mm was produced by the above production method. The fabricated device sample was annealed in a nitrogen (N2) atmosphere at 150°C for 210 minutes.

[0180] [ka]

[0181] (Experimental Example 2) In Experimental Example 2, a device sample (Experimental Example 2) was produced using the same method as in Experimental Example 1, except that the electron injection promotion layer 26 was not formed.

[0182] (Experimental Example 3) In Experimental Example 3, the photoelectric conversion layer 24 was formed by mixing BP-rBDT shown in the above formula (3) and fullerene C 60 A device sample (Experimental Example 3) was fabricated using the same method as in Experimental Example 1, except that the mixed layer was formed to a thickness of 230 nm at a substrate temperature of 40° C. and at film formation rates of 0.50 Å / sec and 0.50 Å / sec, respectively.

[0183] (Experimental Example 4) In Experimental Example 4, a device sample (Experimental Example 4) was produced using the same method as in Experimental Example 3, except that the electron injection promotion layer 26 was not formed.

[0184] (Experimental Example 5) In Experimental Example 5, a device sample (Experimental Example 5) was produced using the same method as in Experimental Example 1, except that the electron injection promotion layer 26 was formed to a thickness of 2 nm using CzBDF represented by the following formula (6).

[0185] [ka]

[0186] (Experimental Example 6) In Experimental Example 6, a device sample (Experimental Example 6) was produced using the same method as in Experimental Example 1, except that the electron injection promotion layer 26 was formed to a thickness of 2 nm using NBphen represented by the following formula (7).

[0187] [ka]

[0188] (Experimental Example 7) In Experimental Example 7, a device sample (Experimental Example 7) was produced using the same method as in Experimental Example 1, except that the electron injection promotion layer 26 was formed to a thickness of 2 nm using BCP represented by the following formula (8).

[0189] [ka]

[0190] (Experimental Example 8) In Experimental Example 8, a device sample (Experimental Example 8) was produced using the same method as in Experimental Example 1, except that the electron injection promotion layer 26 was formed using LiF to a thickness of 2 nm.

[0191] Using the evaluation method described below, the energy levels of the electron injection promotion layers 26 formed in the above Experimental Examples 1 to 8 were analyzed, and the dark current, external quantum efficiency (EQE), and photoresponsiveness of each device sample in Experimental Examples 1 to 6 were evaluated. The results are summarized in Table 1.

[0192] (Energy Level Evaluation) Samples were prepared by depositing an ITO film and a single film of each material to be measured on a quartz substrate, and each energy level was determined by UPS and LEIPS.

[0193] (Evaluation of dark current) The dark current was evaluated by controlling the bias voltage applied between the electrodes of the photoelectric conversion element using a semiconductor parameter analyzer in a dark state, and measuring the current value when the voltage applied to the lower electrode 21 relative to the upper electrode 27 was set to -2.6 V.

[0194] (Evaluation of external photoelectric conversion efficiency) The external photoelectric conversion efficiency was evaluated with the wavelength of light irradiated from a light source to the device sample through a filter at 560 nm and the light intensity at 1.62 μW / cm 2 The bias voltage applied between the electrodes of the device sample was controlled using a semiconductor parameter analyzer, and the effective number of carriers was calculated by subtracting the dark current value from the bright current value when the voltage applied to the lower electrode 21 with respect to the upper electrode 27 was set to 2.6 V. The external photoelectric conversion efficiency was calculated by dividing this by the number of incident photons. The characteristic values ​​of Experimental Example 2 were normalized to 1, and a relative comparison was made.

[0195] (Evaluation of light response) The photoresponsivity was evaluated by controlling the bias voltage applied between the electrodes of the device sample using a semiconductor parameter analyzer, and measuring the decrease in current value after light irradiation when the voltage applied to the lower electrode 21 relative to the upper electrode 27 was set to 2.6 V. After light irradiation, the current value was integrated from 1 ms to 110 ms after the light was blocked, and evaluated as a relative value. The smaller the value, the better the photoresponsivity.

[0196] [Table 1]

[0197] From Table 1, it was confirmed that the photoresponse tends to improve when the in-gap level has a density of states of 1 / 10000 or more of the HOMO level. In addition, it was confirmed that the photoresponse tends to improve as the values ​​of B / A, B / A', a / b, and a / b' become larger.

[0198] Although the above describes the embodiments, examples, and application examples, the present disclosure is not limited to the above embodiments, and various modifications are possible. For example, in the above embodiment, the imaging element is configured by stacking the organic photoelectric conversion unit 20 that detects green light and the inorganic photoelectric conversion units 32B and 32R that detect blue light and red light, respectively, but the present disclosure is not limited to such a structure. That is, the organic photoelectric conversion unit may detect red light or blue light, or the inorganic photoelectric conversion unit may detect green light.

[0199] Furthermore, the number and ratio of these organic photoelectric conversion units and inorganic photoelectric conversion units are not limited, and two or more organic photoelectric conversion units may be provided, or color signals of multiple colors may be obtained using only the organic photoelectric conversion units.

[0200] Furthermore, in the above embodiment, an example has been shown in which the multiple electrodes constituting the lower electrode 21 are composed of two electrodes, the read electrode 21A and the storage electrode 21B, but in addition to this, three or four or more electrodes such as a transfer electrode or an exhaust electrode may be provided.

[0201] Furthermore, in the above embodiment, an example was shown in which the lower electrode 21 was formed using multiple electrodes, but the present technology can also obtain the same effect in an imaging element having a lower electrode consisting of a single electrode.

[0202] It should be noted that the effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0203] The present disclosure may be configured as follows. According to the present technology configured as follows, a first semiconductor layer containing at least one of a carbon-containing compound having an electron affinity larger than the work function of the first electrode and an inorganic compound having a work function larger than the work function of the first electrode is provided between a second electrode arranged opposite to the first electrode with an organic layer including at least a photoelectric conversion layer therebetween, and a second semiconductor layer is provided between the second electrode and the first semiconductor layer, in which the absolute value B of the difference between the HOMO level and the Fermi level of the second electrode is equal to or larger than the absolute value A of the difference between the first LUMO level and the Fermi level calculated from the optical band gap, or in which a gap level having a density of states equal to or larger than 1 / 10000 of the HOMO level is provided near the Fermi level, so that the injection of electrons from the second electrode to the first semiconductor layer is promoted, and the photoresponse can be improved. (1) A first electrode; a second electrode disposed opposite the first electrode; an organic layer provided between the first electrode and the second electrode and including at least a photoelectric conversion layer; a first semiconductor layer provided between the second electrode and the organic layer, the first semiconductor layer including at least one of a carbon-containing compound having an electron affinity larger than a work function of the first electrode and an inorganic compound having a work function larger than a work function of the first electrode; a second semiconductor layer provided between the second electrode and the first semiconductor layer, the absolute value B of a difference between a HOMO (Highest Occupied Molecular Orbital) level and a Fermi level of the second electrode being equal to or greater than an absolute value A of a difference between a first LUMO (Lowest Unoccupied Molecular Orbital) level calculated from an optical band gap and the Fermi level, or the second semiconductor layer having an in-gap level with a density of states equal to or greater than 1 / 10000 of the HOMO level in the vicinity of the Fermi level; An imaging element comprising: (2) The imaging element according to (1), wherein the absolute value B of the difference between the HOMO level and the Fermi level of the second semiconductor layer is greater than the absolute value A' of the difference between a second LUMO level and the Fermi level. (3) The imaging element according to (1) or (2), wherein an absolute value b of a difference between the HOMO level and the intra-gap level of the second semiconductor layer is equal to or greater than twice an absolute value a of a difference between the first LUMO level and the intra-gap level. (4) The imaging element according to any one of (1) to (3), wherein an absolute value b of a difference between the HOMO level and the in-gap level of the second semiconductor layer is 1.5 times or more an absolute value a' of a difference between a second LUMO level and the in-gap level. (5) The imaging element according to any one of (1) to (4), wherein a work function of the second electrode is smaller than a work function of the first semiconductor layer. (6) the organic layer adjacent to the first semiconductor layer comprises an organic material; The imaging element according to any one of (1) to (5), wherein a HOMO level of the organic material has an energy level shallower than a work function of the first semiconductor layer. (7) the organic layer adjacent to the first semiconductor layer comprises an organic material; The imaging element according to any one of (1) to (6), wherein the organic material has a glass transition point higher than 100° C. (8) The imaging element according to any one of (1) to (7), wherein the first semiconductor layer has a light absorptance of 10% or less for visible light. (9) a third semiconductor layer including an oxide semiconductor material between the first electrode and the organic layer; The imaging element according to any one of (1) to (8), wherein a minimum of a conduction band of the oxide semiconductor material has an energy level shallower than a work function of the first electrode. (10) The imaging element according to any one of (1) to (9), wherein the first electrode is composed of a plurality of electrodes independent of each other. (11) The imaging element according to (10), wherein the first electrode has a charge readout electrode and a charge storage electrode as the plurality of electrodes. (12) The imaging element according to (11), wherein a voltage is applied to each of the plurality of electrodes individually. (13) a third semiconductor layer including an oxide semiconductor material between the first electrode and the organic layer; An insulating layer is further provided between the first electrode and the third semiconductor layer, The image sensor according to (11) or (12), wherein the charge readout electrode is electrically connected to the third semiconductor layer through an opening provided in the insulating layer. (14) The imaging element according to any one of (1) to (13), wherein the first electrode is disposed on a side of the organic layer opposite to a light incident surface. (15) The imaging element described in any one of (1) to (14), wherein an organic photoelectric conversion unit having one or more of the organic layers and one or more inorganic photoelectric conversion units performing photoelectric conversion in a wavelength range different from that of the organic photoelectric conversion unit are stacked. (16) The inorganic photoelectric conversion unit is formed by embedding the inorganic photoelectric conversion unit in a semiconductor substrate, The imaging element according to (15), wherein the organic photoelectric conversion section is formed on a first surface side of the semiconductor substrate. (17) The image sensor according to (16), wherein a multilayer wiring layer is formed on the second surface side of the semiconductor substrate. (18) the organic photoelectric conversion unit performs photoelectric conversion of green light, The imaging element according to (16) or (17), wherein an inorganic photoelectric conversion section that performs photoelectric conversion of blue light and an inorganic photoelectric conversion section that performs photoelectric conversion of red light are stacked inside the semiconductor substrate. (19) A plurality of pixels, each of which is provided with one or more imaging elements, The imaging element includes: A first electrode; a second electrode disposed opposite the first electrode; an organic layer including a photoelectric conversion layer provided between the first electrode and the second electrode; a first semiconductor layer provided between the second electrode and the organic layer, the first semiconductor layer including at least one of a carbon-containing compound having an electron affinity larger than a work function of the first electrode and an inorganic compound having a work function larger than a work function of the first electrode; a second semiconductor layer provided between the second electrode and the first semiconductor layer, the absolute value B of a difference between a HOMO (Highest Occupied Molecular Orbital) level and a Fermi level of the second electrode being equal to or greater than an absolute value A of a difference between a first LUMO (Lowest Unoccupied Molecular Orbital) level calculated from an optical band gap and the Fermi level, or the second semiconductor layer having an in-gap level with a density of states equal to or greater than 1 / 10000 of the HOMO level in the vicinity of the Fermi level; An imaging device having the above configuration. (20) The imaging device according to (19), wherein the first electrode is formed for each pixel, and the pixel includes the plurality of electrodes.

[0204] This application claims priority based on Japanese Patent Application No. 2020-012779, filed on January 29, 2020 in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0205] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur to those skilled in the art depending on design requirements and other factors, and that such modifications are within the scope of the appended claims and their equivalents.

Claims

1. A first electrode; a second electrode disposed opposite the first electrode; an organic layer provided between the first electrode and the second electrode and including at least a photoelectric conversion layer; a first semiconductor layer provided between the second electrode and the organic layer, the first semiconductor layer including at least one of a carbon-containing compound having an electron affinity larger than a work function of the first electrode and an inorganic compound having a work function larger than a work function of the first electrode; a second semiconductor layer provided between the second electrode and the first semiconductor layer, the absolute value B of a difference between a HOMO (Highest Occupied Molecular Orbital) level and a Fermi level of the second electrode being equal to or greater than an absolute value A of a difference between a first LUMO (Lowest Unoccupied Molecular Orbital) level calculated from an optical band gap and the Fermi level, or the second semiconductor layer having an in-gap level with a density of states equal to or greater than 1 / 10000 of the HOMO level in the vicinity of the Fermi level; An imaging element comprising:

2. The image sensor according to claim 1 , wherein the absolute value B of the difference between the HOMO level and the Fermi level of the second semiconductor layer is greater than an absolute value A′ of the difference between a second LUMO level and the Fermi level.

3. 2 . The image sensor according to claim 1 , wherein an absolute value b of a difference between the HOMO level and the intra-gap level of the second semiconductor layer is equal to or greater than twice an absolute value a of a difference between the first LUMO level and the intra-gap level.

4. 2. The image sensor according to claim 1, wherein an absolute value b of a difference between the HOMO level and the in-gap level of the second semiconductor layer is 1.5 times or more an absolute value a' of a difference between a second LUMO level and the in-gap level.

5. The image sensor according to claim 1 , wherein a work function of the second electrode is smaller than a work function of the first semiconductor layer.

6. the organic layer adjacent to the first semiconductor layer comprises an organic material; The image sensor according to claim 1 , wherein a HOMO level of the organic material has an energy level shallower than a work function of the first semiconductor layer.

7. the organic layer adjacent to the first semiconductor layer comprises an organic material; The imaging device according to claim 1 , wherein the organic material has a glass transition temperature higher than 100° C.

8. The image sensor according to claim 1 , wherein the first semiconductor layer has a light absorptance of 10% or less for visible light.

9. a third semiconductor layer including an oxide semiconductor material between the first electrode and the organic layer; The image sensor according to claim 1 , wherein the minimum of the conduction band of the oxide semiconductor material has an energy level shallower than a work function of the first electrode.

10. The image sensor according to claim 1 , wherein the first electrode is made up of a plurality of electrodes independent of each other.

11. The imaging device according to claim 10 , wherein the first electrode includes a charge readout electrode and a charge storage electrode as the plurality of electrodes.

12. The imaging device according to claim 11 , wherein a voltage is applied to each of the plurality of electrodes individually.

13. a third semiconductor layer including an oxide semiconductor material between the first electrode and the organic layer; An insulating layer is further provided between the first electrode and the third semiconductor layer, The image sensor according to claim 11 , wherein the charge readout electrode is electrically connected to the third semiconductor layer through an opening provided in the insulating layer.

14. The image sensor according to claim 1 , wherein the first electrode is disposed on a side of the organic layer opposite to a light incident surface.

15. The imaging element according to claim 1 , wherein an organic photoelectric conversion unit having one or more of the organic layers and one or more inorganic photoelectric conversion units performing photoelectric conversion in a wavelength range different from that of the organic photoelectric conversion unit are stacked.

16. The inorganic photoelectric conversion unit is formed by embedding the inorganic photoelectric conversion unit in a semiconductor substrate, The image sensor according to claim 15 , wherein the organic photoelectric conversion section is formed on a first surface side of the semiconductor substrate.

17. The image sensor according to claim 16 , wherein a multi-layer wiring layer is formed on the second surface side of the semiconductor substrate.

18. the organic photoelectric conversion unit performs photoelectric conversion of green light, The image sensor according to claim 16 , wherein an inorganic photoelectric conversion section that performs photoelectric conversion of blue light and an inorganic photoelectric conversion section that performs photoelectric conversion of red light are stacked inside the semiconductor substrate.

19. A plurality of pixels each having one or more imaging elements provided thereon; The imaging element includes: A first electrode; a second electrode disposed opposite the first electrode; an organic layer including a photoelectric conversion layer provided between the first electrode and the second electrode; a first semiconductor layer provided between the second electrode and the organic layer, the first semiconductor layer including at least one of a carbon-containing compound having an electron affinity larger than a work function of the first electrode and an inorganic compound having a work function larger than a work function of the first electrode; a second semiconductor layer provided between the second electrode and the first semiconductor layer, the absolute value B of a difference between a HOMO (Highest Occupied Molecular Orbital) level and a Fermi level of the second electrode being equal to or greater than an absolute value A of a difference between a first LUMO (Lowest Unoccupied Molecular Orbital) level calculated from an optical band gap and the Fermi level, or the second semiconductor layer having an in-gap level with a density of states equal to or greater than 1 / 10000 of the HOMO level in the vicinity of the Fermi level; An imaging device having the above configuration.

20. The imaging device according to claim 19 , wherein the first electrode is formed for each pixel, and the pixel includes the plurality of electrodes.

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