Light detection device

Abstract

A first light detection device according to an embodiment of the present disclosure comprises: a first electrode; a second electrode disposed so as to face the first electrode; a photoelectric conversion layer provided between the first electrode and the second electrode; a work function adjustment layer provided between the photoelectric conversion layer and the second electrode; and a plurality of electron blocking layers provided between the photoelectric conversion layer and the work function adjustment layer and having ionization energy that becomes shallower in order from the photoelectric conversion layer side toward the work function adjustment layer.

Description

Photodetector

[0001] The present disclosure relates to a photodetector including a photoelectric conversion layer using, for example, an organic material.

[0002] For example, Patent Document 1 discloses an imaging device that improves image quality by providing a photoelectric conversion layer containing an organic material between a first electrode and a second electrode consisting of a plurality of electrodes arranged opposite each other, and further providing a first semiconductor layer between the first electrode and the photoelectric conversion layer and a second semiconductor layer between the second electrode and the photoelectric conversion layer. In this imaging device, the first semiconductor layer is formed containing an n-type semiconductor material, and the second semiconductor layer is formed 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.

[0003] International Publication No. 2020 / 027081

[0004] Incidentally, there is a demand for improved light response in photodetection devices.

[0005] It would be desirable to provide a photodetector device that can improve photoresponsiveness.

[0006] A first photodetector according to one embodiment of the present disclosure includes a first electrode, a second electrode disposed opposite the first electrode, a photoelectric conversion layer provided between the first electrode and the second electrode, a work function adjustment layer provided between the photoelectric conversion layer and the second electrode, and a plurality of electron blocking layers provided between the photoelectric conversion layer and the work function adjustment layer, the ionization energies of which become shallower in the direction from the photoelectric conversion layer side toward the work function adjustment layer side.

[0007] In a first photodetector according to an embodiment of the present disclosure, a plurality of electron blocking layers having shallower ionization energies are provided between the photoelectric conversion layer and the work function adjustment layer, from the photoelectric conversion layer side toward the work function adjustment layer side, thereby improving the transportability of holes from the photoelectric conversion layer to the second electrode side and confining holes at the interface between the electron blocking layer and the work function adjustment layer, thereby improving the charge density.

[0008] A second photodetector according to an embodiment of the present disclosure includes a first electrode, a second electrode disposed opposite to the first electrode, a photoelectric conversion layer provided between the first electrode and the second electrode, an electron blocking layer provided between the photoelectric conversion layer and the second electrode, and an electrostatic potential ESP that is provided between the electron blocking layer and the second electrode and satisfies the following mathematical formula (3): ｍｉｎ and an electron injection layer having ESP (Equation 1) - 0.11 ≤ ESP ｍｉｎ ≦−0.09 (3)

[0009] In a second photodetector according to an embodiment of the present disclosure, an electron injection layer that satisfies the above formula (3) is provided between the electron blocking layer and the second electrode, thereby improving the injection of electrons from the second electrode and increasing the charge density at the interface between the electron blocking layer and the second electrode.

[0010] A third photodetector according to an embodiment of the present disclosure includes a first electrode, a second electrode disposed opposite to the first electrode, a photoelectric conversion layer provided between the first electrode and the second electrode, and a photoelectric conversion layer provided between the second electrode and the photoelectric conversion layer in contact with the second electrode, the photoelectric conversion layer having a minimum binding energy Eb １ or the first intermediate layer having the lowest binding energy Eb １ , the nth lowest binding energy Eb ｎ (n≧2) and the n+1 lowest n+1 binding energy Eb ｎ＋１ (n≧2), and the nth binding energy Eb ｎ , the n+1th bond energy Eb ｎ＋１ and the electron affinity change ΔEA when all bonds from the lowest bond energy to the nth bond energy are dissociated and replaced with hydrogen. ｎ and a second intermediate layer that satisfies the following formulas (5), (6), and (7): −5.33 eV<Eb (Formula 2) １ <8.67eV...(4) (Math. 3) Eb ｎ ≦5.33eV (5) 5.33eV<Eb ｎ＋１ <8.67eV...(6) ΔEA ｎ <0.3 (7)

[0011] A third photodetector according to an embodiment of the present disclosure has an intermediate layer (first intermediate layer) that satisfies the above formula (4) or an intermediate layer (second intermediate layer) that satisfies the above formulas (5), (6), and (7) provided directly below the second electrode, thereby suppressing the formation of an interfacial barrier in the layer directly below where the second electrode is to be formed.

[0012] FIG. 1 is a cross-sectional view schematically illustrating an example of a configuration of a photodetector according to a first embodiment of the present disclosure. FIG. 2A is a plan view schematically illustrating an example of a pixel configuration of a photodetector including the photodetector shown in FIG. 1. FIG. 2B is a plan view schematically illustrating another example of a pixel configuration of a photodetector including the photodetector shown in FIG. 1. FIG. 3 is a cross-sectional view schematically illustrating an example of a configuration of a photoelectric conversion unit shown in FIG. 1. FIG. 4 is a diagram illustrating the relationship between energy levels of each layer constituting the photoelectric conversion unit shown in FIG. 3. FIG. 5 is an equivalent circuit diagram of the photodetector shown in FIG. 1. FIG. 6 is a schematic diagram illustrating the arrangement of transistors constituting the lower electrode and control unit of the photodetector shown in FIG. 1. FIG. 7 is a cross-sectional view for explaining a method of manufacturing the photodetector shown in FIG. 1. FIG. 8 is a cross-sectional view illustrating a process subsequent to FIG. 7. FIG. 9 is a cross-sectional view illustrating a process subsequent to FIG. 8. FIG. 10 is a cross-sectional view illustrating a process subsequent to FIG. 9. FIG. 11 is a cross-sectional view illustrating a process subsequent to FIG. 10. FIG. 12 is a cross-sectional view illustrating a process subsequent to FIG. 11. FIG. 13 is a timing chart illustrating an example of an operation of the photodetector shown in FIG. 1. FIG. 14 is a cross-sectional view schematically illustrating an example of the configuration of a photodetector according to a second embodiment of the present disclosure. FIG. 15 is a cross-sectional view schematically illustrating an example of the configuration of a photoelectric conversion unit shown in FIG. 14. FIG. 16 is a diagram illustrating the relationship between energy levels of each layer constituting the photoelectric conversion unit shown in FIG. 15. FIG. 17 is a cross-sectional view schematically illustrating an example of the configuration of a photodetector according to a third embodiment of the present disclosure. FIG. 18 is a cross-sectional view schematically illustrating an example of the configuration of the photoelectric conversion unit shown in FIG. 17. FIG. 19 is a diagram illustrating the relationship between energy levels of each layer constituting the photoelectric conversion unit shown in FIG. 18. FIG. 20 is a cross-sectional view schematically illustrating another example of the configuration of the photoelectric conversion unit shown in FIG. 17. FIG. 21 is a diagram illustrating the relationship between energy levels of each layer constituting the photoelectric conversion unit shown in FIG. 20. FIG. 22A is a cross-sectional view schematically illustrating an example of the configuration of a photodetector according to a first modification of the present disclosure. FIG. 22B is a plan view schematically illustrating an example of the pixel configuration of a photodetector device including the photodetector shown in FIG. 22A. Fig. 23A is a cross-sectional schematic diagram showing an example of the configuration of a photodetector according to Modification 2 of the present disclosure. Fig. 23B is a planar schematic diagram showing an example of the pixel configuration of a photodetector having the photodetector shown in Fig. 23A. Fig. 24 is a cross-sectional schematic diagram showing an example of the configuration of a photodetector according to Modification 3 of the present disclosure.FIG. 25 is a cross-sectional schematic diagram illustrating another example of the configuration of a photodetector element according to Modification 4 of the present disclosure. FIG. 26A is a cross-sectional schematic diagram illustrating another example of the configuration of a photodetector element according to Modification 5 of the present disclosure. FIG. 26B is a plan view schematic diagram illustrating an example of a pixel configuration of a photodetector device including the photodetector element shown in FIG. 26A. FIG. 27A is a cross-sectional schematic diagram illustrating another example of the configuration of a photodetector element according to Modification 6 of the present disclosure. FIG. 27B is a plan view schematic diagram illustrating an example of a pixel configuration of a photodetector device including the photodetector element shown in FIG. 27A. FIG. 28 is a cross-sectional schematic diagram illustrating another example of the configuration of a photodetector element according to Modification 7 of the present disclosure. FIG. 29 is a block diagram illustrating the configuration of a photodetector device using the photodetector element shown in FIG. 1 etc. as a pixel. FIG. 30 is a functional block diagram illustrating an example of an electronic device (camera) using the photodetector shown in FIG. 29. FIG. 31A is a schematic diagram illustrating an example of the overall configuration of a photodetection system using the photodetector shown in FIG. 29. FIG. 31B is a diagram illustrating an example of the circuit configuration of the photodetection system shown in FIG. 31A. Fig. 32 is a diagram showing an example of a schematic configuration of an endoscopic surgery system. Fig. 33 is a block diagram showing an example of a functional configuration of a camera head and a CCU. Fig. 34 is a block diagram showing an example of a schematic configuration of a vehicle control system. Fig. 35 is an explanatory diagram showing an example of installation positions of an outside-vehicle information detection unit and an imaging unit. Fig. 36 is a cross-sectional schematic diagram showing an example of the configuration of a photoelectric conversion unit as another modified example of the present disclosure.

[0013] 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 aspects. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each drawing. The description will be given in the following order. 1. First Embodiment (Example of a photodetector having an electron blocking layer consisting of multiple layers between a photoelectric conversion layer and a work function adjustment layer) 1-1. Configuration of the photodetector 1-2. Method for manufacturing the photodetector 1-3. Signal acquisition operation of the photodetector 1-4. Actions and effects 2. Second Embodiment (Example of a photodetector having an electron injection layer between the work function adjustment layer and the upper electrode) 3-1. Configuration of the photodetector 3-2. Actions and effects 3. Third Embodiment (Example of a photodetector in which an intermediate layer having a predetermined binding energy is provided directly below the upper electrode) 5-1. Configuration of the photodetector 5-2. Actions and effects 4. Modifications 4-1. 4.1. Modification 1 (an example of a photodetector that separates light using a color filter) 4-2. Modification 2 (another example of a photodetector that separates light using a color filter) 4-3. Modification 3 (an example of a photodetector in which multiple photoelectric conversion units are stacked) 4-4. Modifications 4 to 7 (other modifications of the photodetector) 5. Application examples 6. Application examples 7. Examples

[0014] 1. First Embodiment FIG. 1 illustrates a cross-sectional configuration of a photodetector element (photodetector element 1) according to a first embodiment of the present disclosure. The photodetector element 1 constitutes one pixel (unit pixel P) repeatedly arranged in an array in a pixel section 100A of a photodetector device (e.g., photodetector device 100, see FIG. 29 ), such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor used in electronic devices such as digital still cameras and video cameras. FIG. 2A schematically illustrates an example of a pixel configuration of the photodetector device 100 having the photodetector element 1 illustrated in FIG. 1 , and FIG. 1 illustrates a cross section taken along line II illustrated in FIG. 2A . FIG. 3 schematically illustrates an enlarged cross-sectional configuration of a main portion (photoelectric conversion section 20) of the photodetector element 1 illustrated in FIG. 1 . In the pixel section 100A, as shown in FIG. 2A, a pixel unit 1a consisting of four unit pixels P arranged in, for example, two rows and two columns is a repeating unit, and is repeatedly arranged in an array consisting of row and column directions.

[0015] The photodetector element 1 of this embodiment includes a photoelectric conversion unit 20 provided on the light incident side S1 of the semiconductor substrate 30, and includes, in this order, a lower electrode 21 including a readout electrode 21A and a storage electrode 21B, an insulating layer 22, an oxide semiconductor layer 23, a photoelectric conversion layer 24, an electron blocking layer 25, a work function adjustment layer 26, and an upper electrode 27. The electron blocking layer 25 has a structure in which a plurality of layers (for example, three layers, namely, a first layer 25A, a second layer 25B, and a third layer 25C, in this order from the photoelectric conversion layer 24 side) are stacked, and the ionization energy of each layer is configured to become shallower from the photoelectric conversion layer 24 side toward the work function adjustment layer 26.

[0016] Here, the lower electrode 21 corresponds to a specific example of a "first electrode" according to an embodiment of the present disclosure. The oxide semiconductor layer 23 corresponds to a specific example of an "oxide semiconductor layer" according to an embodiment of the present disclosure. The photoelectric conversion layer 24 corresponds to a specific example of a "photoelectric conversion layer" according to an embodiment of the present disclosure. The first layer 25A, the second layer 25B, and the third layer 25C correspond to a specific example of a "multiple electron blocking layers" according to an embodiment of the present disclosure. The work function adjustment layer 26 corresponds to a specific example of a "work function adjustment layer" according to an embodiment of the present disclosure. The upper electrode 27 corresponds to a specific example of a "second electrode" according to an embodiment of the present disclosure.

[0017] (1-1. Configuration of Photodetector) The photodetector 1 is a so-called vertical spectroscopic photodetector in which, for example, one photoelectric conversion unit 20 and two photoelectric conversion regions 32B, 32R are stacked vertically. The photoelectric conversion unit 20 is provided on the back surface (first surface 30A) of the semiconductor substrate 30. The photoelectric conversion regions 32B, 32R are embedded in the semiconductor substrate 30 and stacked in the thickness direction of the semiconductor substrate 30.

[0018] The photoelectric conversion unit 20 and the photoelectric conversion regions 32B and 32R selectively detect light in different wavelength ranges and perform photoelectric conversion. For example, the photoelectric conversion unit 20 acquires a green (G) color signal. The photoelectric conversion regions 32B and 32R acquire blue (B) and red (R) color signals, respectively, due to differences in absorption coefficients. This allows the photodetector 1 to acquire multiple types of color signals in one pixel without using color filters.

[0019] In this embodiment, a case where electrons, among pairs of electrons and holes (excitons) generated by photoelectric conversion, are read out as signal charges (when an n-type semiconductor region is used as the photoelectric conversion layer) will be described. In addition, in the figures, a "+ (plus)" attached to "p" and "n" indicates that the p-type or n-type impurity concentration is high.

[0020] The surface (second surface 30B) of the semiconductor substrate 30 is provided with, for example, floating diffusions FD1 (region 36B within the semiconductor substrate 30), FD2 (region 37C within the semiconductor substrate 30), and FD3 (region 38C within the semiconductor substrate 30), transfer transistors Tr2 and Tr3, an amplifier transistor (modulation element) AMP, a reset transistor RST, and a selection transistor SEL. The second surface 30B of the semiconductor substrate 30 is further provided with a multilayer wiring layer 40 via a gate insulating layer 33. The multilayer wiring layer 40 has, for example, wiring layers 41, 42, and 43 stacked within an insulating layer 44. A vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and input / output terminals 116 (described later) are provided around the periphery of the semiconductor substrate 30, i.e., around the pixel section 100A.

[0021] 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.

[0022] The photoelectric conversion unit 20 includes an oxide semiconductor layer 23, a photoelectric conversion layer 24 containing an organic material, a multi-layer electron blocking layer 25, and a work function adjustment layer 26 stacked in this order from the lower electrode 21 side between an opposing lower electrode 21 and an upper electrode 27. As will be described in detail later, the electron blocking layer 25 prevents electrons from moving from the upper electrode 27 side to the photoelectric conversion layer 24 and efficiently transports holes generated in the photoelectric conversion layer 24 to the interface between the electron blocking layer 25 and the work function adjustment layer 26. The electron blocking layer 25 includes a first layer 25A, a second layer 25B, and a third layer 25C. The photoelectric conversion layer 24 includes a p-type semiconductor and an n-type semiconductor and has a bulk heterojunction structure within the layer. The bulk heterojunction structure is a p / n junction surface formed by mixing p-type and n-type semiconductors.

[0023] The photoelectric conversion unit 20 further includes an insulating layer 22 between the lower electrode 21 and the oxide semiconductor layer 23. The insulating layer 22 is provided, for example, over the entire surface of the pixel unit 100A, and has an opening 22H above the readout electrode 21A that constitutes the lower electrode 21. The readout electrode 21A is electrically connected to the oxide semiconductor layer 23 through this opening 22H.

[0024] Note that, in FIG. 1 , an example is shown in which the oxide semiconductor layer 23, the photoelectric conversion layer 24, the electron blocking layer 25, the work function adjustment layer 26, and the upper electrode 27 are separately formed for each photodetection element 1, but the oxide semiconductor layer 23, the photoelectric conversion layer 24, the electron blocking layer 25, the work function adjustment layer 26, and the upper electrode 27 may be provided as, for example, a continuous layer common to a plurality of photodetection elements 1.

[0025] 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 laminated. The insulating layer 28 is formed by laminating a layer having a fixed charge (fixed charge layer) 28A and an insulating dielectric layer 28B in this order from the semiconductor substrate 30 side.

[0026] The photoelectric conversion regions 32B and 32R enable the vertical separation of light by utilizing the fact that the wavelength of light absorbed varies depending on the depth of incidence of the light in the semiconductor substrate 30 made of silicon, and each has a pn junction in a predetermined region of the semiconductor substrate 30.

[0027] A through electrode 34 is provided between the first surface 30A and the second surface 30B of the semiconductor substrate 30. An end (upper end) of the through electrode 34 on the light incident side S1 is electrically connected to the readout electrode 21A, and an end (lower end) on the wiring layer side S2 is connected to the connection portion 41A. The photoelectric conversion unit 20 is connected via the through electrode 34 to the gate Gamp of the amplifier transistor AMP and one source / drain region 36B of the reset transistor RST (reset transistor Tr1rst) that also serves as the floating diffusion FD1. This allows the photodetector element 1 to efficiently transfer carriers (here, electrons) generated in the photoelectric conversion unit 20 provided 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 its characteristics.

[0028] As described above, the lower end of the through electrode 34 is connected to the wiring (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 via, for example, a lower second contact 46. The upper end of the through electrode 34 is connected to the readout electrode 21A via, for example, a pad portion 39A and an upper first contact 39C.

[0029] A protective layer 51 is provided above the photoelectric conversion unit 20. In the protective layer 51, for example, wiring 52 and a light-shielding film 53 are provided around the periphery of the pixel unit 100A, which electrically connect the upper electrode 27 to peripheral circuit units such as a vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and an input / output terminal 116. Optical members such as a planarization layer (not shown) and an on-chip lens 54 are further provided above the protective layer 51.

[0030] In the photodetector element 1 of this embodiment, light incident on the photoelectric conversion unit 20 from the light incident side S1 is absorbed by the photoelectric conversion layer 24. The excitons thus generated move to the interface between the electron donors and electron acceptors that make up the photoelectric conversion layer 24, where they undergo exciton dissociation, i.e., dissociation into electrons and holes. The carriers (electrons and holes) generated here are transported to different electrodes by diffusion due to differences in carrier concentration and an internal electric field due to the difference in work function between the anode (e.g., upper electrode 27) and the cathode (e.g., lower electrode 21), and are detected as photocurrent. The transport direction of the electrons and holes can also be controlled by applying a potential between the lower electrode 21 and the upper electrode 27.

[0031] The structure and materials of each part will be described in detail below.

[0032] The photoelectric conversion unit 20 is an organic photoelectric conversion element that absorbs, for example, green light corresponding to a part or all of a selective wavelength range (for example, 450 nm or more and 650 nm or less) and generates excitons.

[0033] The lower electrode 21 is composed of, for example, a readout electrode 21A and a storage electrode 21B arranged in parallel on the interlayer insulating layer 29. The readout electrode 21A is used to transfer carriers generated in the photoelectric conversion layer 24 to the floating diffusion FD1, and is provided for each pixel unit 1a, which is made up of four unit pixels P arranged in two rows and two columns, as shown in FIG. 2A, for example.

[0034] The configuration of the pixel unit 1a is not limited to this, and for example, two unit pixels P arranged in one row and two columns may be used as the pixel unit 1a, as shown in Fig. 2B. In this case, one readout electrode 21A is provided between two unit pixels P adjacent to each other in the column direction.

[0035] The readout electrode 21A 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.

[0036] The storage electrode 21B is provided for each unit pixel P to store, as signal charges, electrons, among carriers generated in the photoelectric conversion layer 24, in the oxide semiconductor layer 23. The storage electrode 21B is provided for each unit pixel P in a region that directly faces the light-receiving surfaces of the photoelectric conversion regions 32B and 32R formed in the semiconductor substrate 30 and covers these light-receiving surfaces. The storage electrode 21B is preferably larger than the readout electrode 21A, allowing for the storage of a larger number of carriers. As shown in FIG. 6 , the voltage application unit 56 is connected to the storage electrode 21B via wiring, such as an upper first contact 39C and an upper second contact 39D.

[0037] The lower electrode 21 is made of, for example, a conductive film having optical transparency. The lower electrode 21 preferably has a work function of 4.0 eV or more and 5.5 eV or less. The material for the lower electrode 21 is, for example, InP doped with tin (Sn). ２ O ３ The ITO thin film may have high or low crystallinity (approaching amorphous). In addition to the above, the lower electrode 21 may also be made of a material such as tin oxide (SnO ２ )-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine added as a dopant can be used. Zinc oxide (ZnO) or a zinc oxide-based material with a dopant added can also be used. Examples of ZnO-based materials include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, boron zinc oxide with boron (B) added, and indium zinc oxide (IZO) with indium (In) added. Furthermore, zinc oxide with indium and gallium added as dopants (IGZO, In-GaZnO ４ In addition, the lower electrode 21 may be made of CuI, InSbO ４ , ZnMgO, CuInO ２ , MgIN ２ O ４ , CdO, ZnSnO３ or TiO ２ Alternatively, spinel oxides or YbFe ２ O ４ Oxides having such a structure may also be used.

[0038] Furthermore, when the lower electrode 21 does not need to be optically transparent (for example, when light is incident from the upper electrode 27 side and the photoelectric conversion regions 32R and 32B are not provided below the storage electrode 21B), a single metal or alloy having a small work function (for example, φ=3.5 eV to 4.5 eV) can be used. Specific examples include alkali metals (for example, lithium (Li), sodium (Na), and potassium (K)) and their fluorides or oxides, and alkaline earth metals (for example, magnesium (Mg) and calcium (Ca)) and their fluorides or oxides. Other examples include rare earth metals such as aluminum (Al), Al—Si—Cu alloys, zinc (Zn), tin (Sn), thallium (Tl), Na—K alloys, Al—Li alloys, Mg—Ag alloys, In, and ytterbium (Yb), or alloys thereof.

[0039] Furthermore, examples of materials for the lower electrode 21 include metals such as platinum (Pt), gold (Au), palladium (Pd), chromium (Cr), nickel (Ni), aluminum (Al), silver (Ag), tantalum (Ta), tungsten (W), copper (Cu), titanium (Ti), indium (In), tin (Sn), iron (Fe), cobalt (Co), and molybdenum (Mo), alloys containing these metal elements, conductive particles made of these metals, conductive particles of alloys containing these metals, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, and graphene. Other examples of materials for the lower electrode 21 include organic materials (conductive polymers) such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT / PSS). Alternatively, the above materials may be mixed with a binder (polymer) to form a paste or ink, which may then be cured and used as an electrode.

[0040] The lower electrode 21 can be formed as a single layer or a laminated film made of the above materials. The film thickness of the lower electrode 21 in the lamination direction (hereinafter simply referred to as thickness) is, for example, 20 nm to 200 nm, and preferably 30 nm to 150 nm.

[0041] The insulating layer 22 serves to electrically separate the storage electrode 21B from the oxide semiconductor layer 23. The insulating layer 22 is provided, for example, on the interlayer insulating layer 29 so as to cover the lower electrode 21. The insulating layer 22 has an opening 22H provided above the readout electrode 21A of the lower electrode 21, and the readout electrode 21A and the oxide semiconductor layer 23 are electrically connected via this opening 22H. The insulating layer 22 is made of, for example, silicon oxide (SiO ｘ ), silicon nitride (SiN ｘ The insulating layer 22 is made of a single layer film made of one of silicon oxynitride (SiON) and silicon oxynitride (SiON), or a laminated film made of two or more of these materials. The thickness of the insulating layer 22 is, for example, 20 nm to 500 nm.

[0042] The oxide semiconductor layer 23 is for accumulating carriers generated in the photoelectric conversion layer 24. The oxide semiconductor layer 23 can be formed using an oxide semiconductor containing at least one element selected from the group consisting of indium (In), gallium (Ga), zinc (Zn), aluminum (Al), and tin (Sn). In this embodiment, electrons among the carriers generated in the photoelectric conversion layer 24 are used as signal charges. For this reason, the oxide semiconductor layer 23 can be formed using an n-type oxide semiconductor material. Specifically, the oxide semiconductor layer 23 can be formed using an n-type oxide semiconductor material such as IGZO (In—Ga—Zn—O-based oxide semiconductor), gallium oxide (Ga ２ O ３ ), ZTO (Zn—Sn—O-based oxide semiconductor), IZO (In—Zn—O-based oxide semiconductor), ITO, indium gallium aluminum oxide (InGaAlO), indium gallium silicon oxide (InGaSiO), etc. The thickness of the oxide semiconductor layer 23 is, for example, 10 nm to 300 nm.

[0043] The photoelectric conversion layer 24 converts light energy into electrical energy. The photoelectric conversion layer 24 is configured, for example, by including two or more organic materials (p-type semiconductor materials or n-type semiconductor materials) that function as p-type or n-type semiconductors, respectively. The photoelectric conversion layer 24 has a junction surface (p / n junction surface) between a p-type semiconductor material and an n-type semiconductor material within the layer. The p-type semiconductor functions relatively as an electron donor, and the n-type semiconductor functions relatively as an electron acceptor. The photoelectric conversion layer 24 provides a site where excitons generated upon light absorption separate into electrons and holes. Specifically, the excitons separate into electrons and holes at the interface (p / n junction surface) between the electron donor and electron acceptor.

[0044] In addition to the p-type and n-type semiconductor materials, the photoelectric conversion layer 24 may also contain an organic material, a so-called dye material, that photoelectrically converts light in a predetermined wavelength range while transmitting light in other wavelength ranges. When the photoelectric conversion layer 24 is formed using three types of organic materials, i.e., a p-type semiconductor material, an n-type semiconductor material, and a dye material, the p-type and n-type semiconductor materials are preferably materials that are optically transparent in the visible range (e.g., 450 nm to 800 nm). The thickness of the photoelectric conversion layer 24 is, for example, 50 nm to 500 nm.

[0045] Examples of organic materials that can be used to form the photoelectric conversion layer 24 include quinacridone derivatives, naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, and fluoranthene derivatives. The photoelectric conversion layer 24 is formed by combining two or more of the above organic materials. Depending on the combination, the above organic materials function as p-type or n-type semiconductors.

[0046] The organic material constituting the photoelectric conversion layer 24 is not particularly limited. In addition to the above organic materials, for example, polymers of phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, and the like, or derivatives thereof, can be used. Alternatively, metal complex dyes, cyanine dyes, merocyanine dyes, phenylxanthene dyes, triphenylmethane dyes, rhodacyanine dyes, xanthene dyes, macrocyclic azaannulene dyes, azulene dyes, naphthoquinone dyes, anthraquinone dyes, condensed polycyclic aromatic compounds such as pyrene, chain compounds in which aromatic rings or heterocyclic compounds are condensed, quinoline having a squarylium group and a croconite methine group as a bonding chain, two nitrogen-containing heterocycles such as benzothiazole and benzoxazole, or cyanine-like dyes bonded by a squarylium group and a croconite methine group, can be used. Examples of the metal complex dye include dithiol metal complex dyes, metal phthalocyanine dyes, metal porphyrin dyes, and ruthenium complex dyes. Of these, ruthenium complex dyes are particularly preferred, but the invention is not limited to these.

[0047] The electron blocking layer 25 prevents electrons from moving from the upper electrode 27 side to the photoelectric conversion layer 24, and efficiently transports holes, among carriers generated in the photoelectric conversion layer 24, to the interface between the electron blocking layer 25 and the work function adjustment layer 26. As described above, the electron blocking layer 25 has a configuration in which a plurality of layers are stacked, and each layer has a cascade structure in which the ionization energy becomes shallower in order from the photoelectric conversion layer 24 side toward the work function adjustment layer 26. Specifically, the electron blocking layer 25 is made up of n layers, and includes a first electron blocking layer adjacent to the photoelectric conversion layer 24, an nth electron blocking layer adjacent to the work function adjustment layer 26, and an (n-1)th electron blocking layer adjacent to the nth electron blocking layer on the opposite side to the work function adjustment layer 26, and the ionization energy of the photoelectric conversion layer 24 is reduced to IP １ , the ionization energy of the first electron blocking layer is IP ２ , the ionization energy of the (n-1)th electron blocking layer is IP ｎ－１ , the ionization energy of the nth electron blocking layer is IPｎ and the electron affinity of the work function adjusting layer 26 is EA ｗ When the electron blocking layer 25 is formed as follows, each layer of the electron blocking layer 25 is configured to satisfy the following formula (1): EA ｗ <IP ｎ ≦IP ｎ－１ +0.03 ... (1)

[0048] As an example, in this embodiment, the electron blocking layer 25 has a three-layer structure in which a first layer 25A, a second layer 25B, and a third layer 25C are stacked in this order from the photoelectric conversion layer 24 side, as shown in FIG. 3 . FIG. 4 shows the relationship between the energy levels of the layers constituting the photoelectric conversion unit 20. The first layer 25A adjacent to the photoelectric conversion layer 24 has an ionization energy shallower than the lowest unoccupied molecular orbital (LUMO) of the photoelectric conversion layer 24, and the third layer 25C adjacent to the work function adjustment layer 26 has an ionization energy deeper than the electron affinity (or work function) of the work function adjustment layer 26. Of the first layer 25A, second layer 25B, and third layer 25C constituting the electron blocking layer 25, the first layer 25A has the highest ionization energy, the third layer 25C has the lowest ionization energy, and the second layer 25B has an ionization energy between the first layer 25A and the third layer 25C. The difference in ionization energy between the third layer 25C adjacent to the work function adjustment layer 26 and the second layer 25B adjacent to the third layer 25C on the opposite side to the work function adjustment layer 26 side is 0.03 eV or more.

[0049] As a result, holes generated in the photoelectric conversion layer 24 are transported without delay to the interface between the electron blocking layer 25 and the work function adjustment layer 26, improving the charge density at the interface between the electron blocking layer 25 (here, the third layer 25C) and the work function adjustment layer 26, and promoting the recombination of electrons and holes at the interface between the electron blocking layer 25 and the work function adjustment layer 26. Therefore, residual charges in the photoelectric conversion layer 24 and the electron blocking layer 25 are reduced, improving photoresponsiveness, such as improving afterimage characteristics.

[0050] The electron blocking layer 25 includes an organic material. Examples of the material for the electron blocking layer 25 include thienoacene-based materials such as naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, quinacridone derivatives, thiophene derivatives, thienothiophene derivatives, benzothiophene derivatives, benzothienobenzothiophene (BTBT) derivatives, dinaphthothienothiophene (DNTT) derivatives, benzobisbenzothiophene (BBBT) derivatives, thienobisbenzothiophene (TBBT) derivatives, dibenzothienobisbenzothiophene (DBTBT) derivatives, dithienobenzodithiophene (DTBDT) derivatives, dibenzothienodithiophene (DBTDT) derivatives, benzodithiophene (BDT) derivatives, naphthodithiophene (NDT) derivatives, and anthracenodithiophene (ADT) derivatives. Other examples of p-type semiconductors include fluorene derivatives, triphenylene derivatives, triphenylamine derivatives, carbazole derivatives, picene derivatives, and chrysene derivatives.

[0051] The electron blocking layer 25 has a total thickness of, for example, 3 nm to 200 nm, and preferably, for example, 10 nm to 100 nm. Each of the layers constituting the electron blocking layer 25 (for example, the first layer 25A, the second layer 25B, and the third layer 25C) has a thickness of, for example, 3 nm to 100 nm.

[0052] The work function adjustment layer 26 has a larger electron affinity or work function than the work function of the upper electrode 27, and improves the electrical connection between the electron blocking layer 25 and the upper electrode 27. Examples of materials constituting the work function adjustment layer 26 include dipyrazino[2,3-f:2',3'v-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN). Other materials constituting the work function adjustment layer 26 include PEDOT / PSS and polyaniline, and MoO ｘ , RuO ｘ , V.O. ｘ and W.O. ｘ and the like metal oxides.

[0053] The upper electrode 27 is made of, for example, a light-transmitting conductive film, similar to the lower electrode 21. The upper electrode 27 is made of, for example, InP doped with tin (Sn). ２ O ３ The crystallinity of the ITO thin film may be high or low (approaching amorphous). In addition to the above, the upper electrode 27 may also be made of tin oxide (SnO ２ )-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine added as a dopant. Zinc oxide (ZnO) or a zinc oxide-based material with a dopant added thereto may also be used. Examples of ZnO-based materials include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, boron zinc oxide with boron (B) added, and indium zinc oxide (IZO) with indium (In) added. Furthermore, zinc oxide with indium and gallium added as dopants (IGZO, In-GaZnO4) may also be used. In addition, materials constituting the upper electrode 27 include CuI, InSbO ４ , ZnMgO, CuInO ２ , MgIN ２ O ４ , CdO, ZnSnO ３ or TiO ２ Alternatively, spinel oxides or YbFe ２ O ４ Oxides having such a structure may also be used.

[0054] Furthermore, if optical transparency is not required for the upper electrode 27, a single metal or alloy having a large work function (for example, φ=4.5 eV to 5.5 eV) can be used. Specific examples include Au, Ag, Cr, Ni, Pd, Pt, Fe, iridium (Ir), germanium (Ge), osmium (Os), rhenium (Re), tellurium (Te), and alloys thereof.

[0055] Furthermore, examples of materials for the upper electrode 27 include metals such as Pt, Au, Pd, Cr, Ni, Al, Ag, Ta, W, Cu, Ti, In, Sn, Fe, Co, and Mo, alloys containing these metal elements, conductive particles made of these metals, conductive particles of alloys containing these metals, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, and conductive substances such as graphene. Other examples of materials for the upper electrode 27 include organic materials (conductive polymers) such as PEDOT / PSS. Furthermore, the above materials may be mixed with a binder (polymer) to form a paste or ink, which may then be hardened and used as an electrode.

[0056] The upper electrode 27 can be formed as a single layer or a multilayer film made of the above materials. The thickness of the upper electrode 27 is, for example, 20 nm to 200 nm, preferably 30 nm to 150 nm.

[0057] In the photoelectric conversion unit 20, other layers may be provided between the lower electrode 21 and the photoelectric conversion layer 24 and between the photoelectric conversion layer 24 and the upper electrode 27. In addition, the photoelectric conversion layer 24 may have a pin bulk heterostructure in which, for example, a p-type blocking layer, a layer containing a p-type semiconductor and an n-type semiconductor (i-layer), and an n-type blocking layer are stacked.

[0058] The insulating layer 28 covers the first surface 30A of the semiconductor substrate 30, reduces the interface state density with the semiconductor substrate 30, and suppresses the generation of dark current from the interface with the semiconductor substrate 30. The insulating layer 28 also extends from the first surface 30A of the semiconductor substrate 30 to the side surface of an opening 34H (see FIG. 8 ) in which a through electrode 34 that penetrates the semiconductor substrate 30 is formed. The insulating layer 28 has, for example, a stacked structure of a fixed charge layer 28A and a dielectric layer 28B.

[0059] The fixed charge layer 28A may be a film having a positive fixed charge or a film having a negative fixed charge. The fixed charge layer 28A is preferably formed using a semiconductor material or a conductive material having a wider band gap than the semiconductor substrate 30. This makes it possible to suppress the generation of dark current at the interface of the semiconductor substrate 30. The fixed charge layer 28A may be formed using, for example, hafnium oxide (HfO ｘ ), aluminum oxide (AlO ｘ ), zirconium oxide (ZrO ｘ ), tantalum oxide (TaO ｘ ), titanium oxide (TiO ｘ ), lanthanum oxide (LaO ｘ ), praseodymium oxide (PrO ｘ ), cerium oxide (CeO ｘ ), neodymium oxide (NdO ｘ ), promethium oxide (PmO ｘ ), samarium oxide (SmO ｘ ), europium oxide (EuO ｘ ), gadolinium oxide (GdO ｘ ), terbium oxide (TbO ｘ ), dysprosium oxide (DyO ｘ ), holmium oxide (HoO ｘ ), thulium oxide (TmO ｘ ), ytterbium oxide (YbO ｘ ), lutetium oxide (LuO ｘ ), yttrium oxide (YO ｘ ), hafnium nitride (HfN ｘ ), aluminum nitride (AlN ｘ ), hafnium oxynitride (HfO ｘ N ｙ ) and aluminum oxynitride (AlO ｘ N ｙ ) etc.

[0060] The dielectric layer 28B is intended to prevent light reflection caused by the difference in refractive index between the semiconductor substrate 30 and the interlayer insulating layer 29. The dielectric layer 28B is preferably formed using a material having a refractive index between the refractive index of the semiconductor substrate 30 and the refractive index of the interlayer insulating layer 29. Examples of materials that can be used to form the dielectric layer 28B include silicon oxide, TEOS, silicon nitride, and silicon oxynitride (SiON).

[0061] The interlayer insulating layer 29 is formed of, for example, a single layer film made of one of silicon oxide, silicon nitride, silicon oxynitride, etc., or a laminated film made of two or more of these materials.

[0062] A shield electrode 21C is provided on the interlayer insulating layer 29 together with the readout electrode 21A and the storage electrode 21B. The shield electrode 21C is intended to prevent capacitive coupling between adjacent pixel units 1a, and is provided, for example, around the pixel unit 1a and has a fixed potential applied to it. For example, in the case of a pixel unit 1a consisting of four unit pixels P arranged in two rows and two columns as shown in FIG. 2A , the shield electrode 21C further extends between adjacent pixels in the row direction (Y-axis direction) and the column direction (X-axis direction).

[0063] The semiconductor substrate 30 is made of, for example, an n-type silicon (Si) substrate, and has a p-well 31 in a predetermined region.

[0064] The photoelectric conversion regions 32B and 32R are each composed of a photodiode (PD) having a pn junction in a predetermined region of the semiconductor substrate 30. They utilize the fact that different wavelengths of light are absorbed depending on the depth of incidence of light in the Si substrate to enable vertical light separation. The photoelectric conversion region 32B selectively detects, for example, blue light and accumulates signal charges corresponding to the blue color, and is located at a depth that allows efficient photoelectric conversion of the blue light. The photoelectric conversion region 32R selectively detects, for example, red light and accumulates signal charges corresponding to the red color, and is located at a depth that allows efficient photoelectric conversion of the red light. Note that blue (B) corresponds to a wavelength range of, for example, 450 nm to 495 nm, and red (R) corresponds to a wavelength range of, for example, 620 nm to 750 nm. Each of the photoelectric conversion regions 32B and 32R may be capable of detecting light in some or all of the respective wavelength ranges.

[0065] The photoelectric conversion region 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 photoelectric conversion region 32R includes, 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 p-n-p stacked structure). The n region of the photoelectric conversion region 32B is connected to the vertical transfer transistor Tr2. The p+ region of the photoelectric conversion region 32B bends along the transfer transistor Tr2 and connects to the p+ region of the photoelectric conversion region 32R.

[0066] The gate insulating layer 33 is configured, for example, as a single layer film made of one of silicon oxide, silicon nitride, silicon oxynitride, etc., or as a laminated film made of two or more of these materials.

[0067] The through electrode 34 is provided between the first surface 30A and the second surface 30B of the semiconductor substrate 30, and functions as a connector between the 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 carriers generated in the photoelectric conversion unit 20. 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 for the reset transistor RST to reset carriers accumulated in the floating diffusion FD1.

[0068] The pad portions 39A, 39B, the upper first contact 39C, the upper second contact 39D, the lower first contact 45, the lower second contact 46, and the wiring 52 can be formed using, for example, a silicon material doped with impurities such as PDAS (Phosphorus Doped Amorphous Silicon), or a metal material such as aluminum (Al), tungsten (W), titanium (Ti), cobalt (Co), hafnium (Hf), and tantalum (Ta).

[0069] The protective layer 51 and the on-chip lens 54 are made of a light-transmitting material, and are formed of, for example, a single layer film made of any of silicon oxide, silicon nitride, silicon oxynitride, etc., or a laminated film made of two or more of these materials. The thickness of this protective layer 51 is, for example, 100 nm to 30,000 nm.

[0070] The light-shielding film 53 is provided, for example, together with the wiring 52, in the protective layer 51 so as to cover at least the region of the readout electrode 21A that is in direct contact with the oxide semiconductor layer 23, but not the storage electrode 21B. The light-shielding film 53 can be formed using, for example, tungsten (W), aluminum (Al), an alloy of Al and copper (Cu), or the like.

[0071] Fig. 5 is an equivalent circuit diagram of the photodetector element 1 shown in Fig. 1. Fig. 6 is a schematic diagram showing the arrangement of the lower electrode 21 and transistors constituting the control section of the photodetector element 1 shown in Fig. 1.

[0072] The reset transistor RST (reset transistor TR1rst) resets carriers transferred from the photoelectric conversion unit 20 to the floating diffusion FD1, and is configured, for example, by a MOS transistor. Specifically, the reset transistor TR1rst is configured by a reset gate Grst, a channel formation region 36A, and source / drain regions 36B and 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.

[0073] The amplifier transistor AMP (amplifier transistor TR1amp) is a modulation element that modulates the amount of charge generated in the photoelectric conversion unit 20 into a voltage, and is configured, for example, by a MOS transistor. Specifically, the amplifier transistor AMP is configured with a gate Gamp, a channel formation region 35A, and source / drain regions 35B and 35C. The gate Gamp is connected to the readout electrode 21A and one source / drain region 36B (floating diffusion FD1) of the reset transistor TR1rst via a lower first contact 45, a connection portion 41A, a lower second contact 46, a through-electrode 34, etc. Furthermore, one source / drain region 35B shares an area with the other source / drain region 36C that constitutes the reset transistor TR1rst, and is connected to the power supply line VDD.

[0074] The select transistor SEL (select 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 select line SEL1. One source / drain region 34B shares an area with the other source / drain region 35C that constitutes the amplifier transistor AMP, and the other source / drain region 34C is connected to a signal line (data output line) VSL1.

[0075] The transfer transistor TR2 (transfer transistor TR2trs) transfers signal charges corresponding to blue generated and accumulated in the photoelectric conversion region 32B to the floating diffusion FD2. Because the photoelectric conversion region 32B is formed deep below the second surface 30B of the semiconductor substrate 30, the transfer transistor TR2trs in the photoelectric conversion region 32B is preferably configured as a vertical transistor. The transfer transistor TR2trs is connected to a transfer gate line TG2. A floating diffusion FD2 is provided in the region 37C near the gate Gtrs2 of the transfer transistor TR2trs. Carriers accumulated in the photoelectric conversion region 32B are read out to the floating diffusion FD2 via a transfer channel formed along the gate Gtrs2.

[0076] The transfer transistor TR3 (transfer transistor TR3trs) transfers the signal charges corresponding to red that are generated and accumulated in the photoelectric conversion region 32R to the floating diffusion FD3, and is configured, for example, by a MOS transistor. The transfer transistor TR3trs is connected to a transfer gate line TG3. A floating diffusion FD3 is provided in the region 38C near the gate Gtrs3 of the transfer transistor TR3trs. Carriers accumulated in the photoelectric conversion region 32R are read out to the floating diffusion FD3 via a transfer channel formed along the gate Gtrs3.

[0077] Further provided on the second surface 30B side of the semiconductor substrate 30 are a reset transistor TR2rst, an amplifier transistor TR2amp, and a selection transistor TR2sel that constitute a control section of the photoelectric conversion region 32B. Further provided are a reset transistor TR3rst, an amplifier transistor TR3amp, and a selection transistor TR3sel that constitute a control section of the photoelectric conversion region 32R.

[0078] The reset transistor TR2rst is composed of a gate, a channel forming region, and source / drain regions. 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.

[0079] The amplifier transistor TR2amp is composed of a gate, a channel forming region, and source / drain regions. The gate is connected to the other source / drain region (floating diffusion FD2) of the reset transistor TR2rst. One of the source / drain regions constituting the amplifier transistor TR2amp shares the same region with one of the source / drain regions constituting the reset transistor TR2rst and is connected to the power supply line VDD.

[0080] The selection transistor TR2sel is composed of a gate, a channel formation region, and source / drain regions. The gate is connected to a selection line SEL2. One of the source / drain regions constituting the selection transistor TR2sel is shared with the other source / drain region constituting the amplifier transistor TR2amp. The other source / drain region constituting the selection transistor TR2sel is connected to a signal line (data output line) VSL2.

[0081] The reset transistor TR3rst is composed of a gate, a channel forming region, and source / drain regions. 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.

[0082] The amplifier transistor TR3amp is composed of a gate, a channel forming region, and source / drain regions. The gate is connected to the other source / drain region (floating diffusion FD3) constituting the reset transistor TR3rst. One of the source / drain regions constituting the amplifier transistor TR3amp shares the same region with one of the source / drain regions constituting the reset transistor TR3rst and is connected to the power supply line VDD.

[0083] The selection transistor TR3sel is composed of a gate, a channel formation region, and source / drain regions. 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.

[0084] The reset lines RST1, RST2, and RST3, the selection lines SEL1, SEL2, and SEL3, and the transfer gate lines TG2 and TG3 are connected to vertical drive circuits that constitute the drive circuit, and the signal lines (data output lines) VSL1, VSL2, and VSL3 are connected to a column signal processing circuit 112 that constitutes the drive circuit.

[0085] (1-2. Method for Manufacturing Photodetector) The photodetector 1 of this embodiment can be manufactured, for example, as follows.

[0086] 7 to 12 show the process sequence of the manufacturing method of the photodetector element 1. First, as shown in Fig. 7, for example, a p-well 31 is formed in a semiconductor substrate 30, and for example, n-type photoelectric conversion regions 32B and 32R are formed in this p-well 31. A p+ region is formed near the first surface 30A of the semiconductor substrate 30.

[0087] 7, n+ regions that will become floating diffusions FD1 to FD3 are formed on the second surface 30B of the semiconductor substrate 30, followed by the formation of a gate insulating layer 33 and a gate wiring layer 47 including the gates of the transfer transistor Tr2, the transfer transistor Tr3, the select transistor SEL, the amplifier transistor AMP, and the reset transistor RST. This results in the formation of the transfer transistor Tr2, the transfer transistor Tr3, the select transistor SEL, the amplifier transistor AMP, and the reset transistor RST. Furthermore, a multilayer wiring layer 40 is formed on the second surface 30B of the semiconductor substrate 30, which includes wiring layers 41 to 43, each including a lower first contact 45, a lower second contact 46, and a connection portion 41A, and an insulating layer 44.

[0088] 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 stacked. 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.

[0089] Next, a support substrate (not shown) or another semiconductor substrate is bonded to the multilayer wiring layer 40 provided on the second surface 30B side of the semiconductor substrate 30, and the semiconductor substrate 30 is then turned upside down. Subsequently, the semiconductor substrate 30 is separated from the buried oxide film of the SOI substrate and the support substrate, exposing the first surface 30A of the semiconductor substrate 30. The above steps can be performed using techniques used in ordinary CMOS processes, such as ion implantation and CVD (Chemical Vapor Deposition).

[0090] 8, the semiconductor substrate 30 is processed from the first surface 30A side by, for example, dry etching to form, for example, an annular 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.

[0091] Next, for example, a fixed charge layer 28A and a dielectric layer 28B are sequentially formed on the first surface 30A of the semiconductor substrate 30 and the side surfaces of the opening 34H. The fixed charge layer 28A can be formed, for example, by depositing a hafnium oxide film or an aluminum oxide film using atomic layer deposition (ALD). The dielectric layer 28B can be formed, for example, by depositing a silicon oxide film using plasma CVD. Next, pad portions 39A and 39B are formed at predetermined positions on the dielectric layer 28B, each of which includes a barrier metal layer made of, for example, a titanium / titanium nitride (Ti / TiN) film and a tungsten film stacked together. This allows the pad portions 39A and 39B to be used as light-shielding films. After that, an interlayer insulating layer 29 is formed on the dielectric layer 28B and the pad portions 39A and 39B, and the surface of the interlayer insulating layer 29 is planarized using CMP (chemical mechanical polishing).

[0092] 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.

[0093] 10, a conductive film 21X is formed on the interlayer insulating layer 29 by, for example, sputtering, and then patterned by photolithography. Specifically, a photoresist PR is formed at a predetermined position on the conductive film 21X, and then the conductive film 21X is processed by dry etching or wet etching. The photoresist PR is then removed, thereby forming the read electrode 21A and the storage electrode 21B as shown in FIG.

[0094] Next, as shown in FIG. 12 , an insulating layer 22, an oxide semiconductor layer 23, a photoelectric conversion layer 24, an electron blocking layer 25, for example, a first layer 25A, a second layer 25B, and a third layer 25C stacked in this order, a work function adjustment layer 26, and an upper electrode 27 are sequentially formed. The insulating layer 22 is formed by depositing a silicon oxide film using, for example, an ALD method, and then planarizing the surface of the insulating layer 22 using a CMP method. An opening 22H is then formed on the readout electrode 21A using, for example, wet etching. The oxide semiconductor layer 23 can be formed using, for example, a sputtering method. The photoelectric conversion layer 24 and the electron blocking layer 25 are formed using, for example, a vacuum deposition method. The work function adjustment layer 26 can be formed using, for example, an ALD method. The upper electrode 27 is formed, similarly to the lower electrode 21, using, for example, a sputtering method. Finally, a protective layer 51 including wiring 52 and a light-shielding film 53, and an on-chip lens 54 are disposed on the upper electrode 27. With the above steps, the photodetector 1 shown in FIG.

[0095] As described above, when other layers containing organic materials, such as the electron blocking layer 25 and the work function adjustment layer, are formed between the photoelectric conversion layer 24 and the upper electrode 27, it is desirable to form each layer consecutively in a vacuum process (through a consistent vacuum process). Furthermore, the method for forming the photoelectric conversion layer 24 and the electron blocking layer 25 is not necessarily limited to a method using vacuum deposition, and for example, spin coating or printing may also be used. Furthermore, methods for forming the transparent electrodes (lower electrode 21 and upper electrode 27) include, in addition to sputtering, physical vapor deposition (PVD) methods such as vacuum deposition, reactive deposition, electron beam deposition, and ion plating, pyrosol deposition, various CVD methods including thermal decomposition of organometallic compounds, spray deposition, dipping, and MOCVD, electroless plating, and electrolytic plating, depending on the material constituting the transparent electrodes.

[0096] (1-3. Signal Acquisition Operation of Photodetection Element) In the photodetection element 1, when light is incident on the photoelectric conversion unit 20 via the on-chip lens 54, the light passes through the photoelectric conversion unit 20 and the photoelectric conversion regions 32B and 32R in that order, and is photoelectrically converted into green, blue, and red light during this passage. The signal acquisition operation for each color will be described below.

[0097] (Acquisition of Green Signal by Photoelectric Conversion Unit 20) Of the light incident on the photodetector element 1, green light (G) is first selectively detected (absorbed) by the photoelectric conversion unit 20 and photoelectrically converted.

[0098] The 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. Therefore, electrons of the excitons generated in the photoelectric conversion unit 20 are extracted from the lower electrode 21 side, transferred to the second surface 30S2 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 photoelectric conversion unit 20 is modulated into a voltage by the amplifier transistor AMP.

[0099] 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.

[0100] Since the 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, the charge accumulated in the floating diffusion FD1 can be easily reset by the reset transistor RST.

[0101] 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 must be applied to extract the charge to the upper electrode 27. This may damage the photoelectric conversion layer 24. Furthermore, a structure that enables resetting in a short time increases dark noise, which is a trade-off, making this structure difficult to implement.

[0102] 13 shows an example of operation of the photodetector element 1. (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 photodetector element 1, voltages are applied to the readout electrode 21A and the storage electrode 21B individually.

[0103] In the photodetector element 1, 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 storage electrode 21B. Here, the relationship between potentials V1 and V2 is V2 > V1. As a result, the charge (signal charge; electrons) generated by photoelectric conversion is attracted to the storage electrode 21B and accumulated in the region of the semiconductor layer 18 facing the storage electrode 21B (accumulation period). Incidentally, the potential of the region of the semiconductor layer 18 facing the storage electrode 21B becomes more negative as the photoelectric conversion time elapses. Note that holes are sent from the upper electrode 27 to the drive circuit.

[0104] In the photodetector element 1, a reset operation is performed in the latter half of the accumulation period. Specifically, at timing t1, the scanning unit changes the voltage of the reset signal RST from low to high. As a result, in the unit pixel P, the reset transistor TR1rst is turned on, and as a result, the voltage of the floating diffusion FD1 is set to the power supply voltage and the voltage of the floating diffusion FD1 is reset (reset period).

[0105] After the reset operation is completed, the charge is read out. Specifically, at timing t2, the drive circuit applies a potential V3 to the readout electrode 21A and a potential V4 to the storage electrode 21B. Here, the potentials V3 and V4 are set to V3 > V4. As a result, the charge stored in the region corresponding to the storage electrode 21B is read out from the readout electrode 21A to the floating diffusion FD1. That is, the charge stored in the semiconductor layer 18 is read out to the control unit (transfer period).

[0106] After the read operation is completed, the drive circuit again applies potential V1 to the read electrode 21A and potential V2 to the storage electrode 21B, causing the charges generated by photoelectric conversion to be attracted to the storage electrode 21B and stored in the region of the photoelectric conversion layer 24 facing the storage electrode 21B (storage period).

[0107] (Acquisition of Blue and Red Signals by Photoelectric Conversion Regions 32B and 32R) Next, of the light transmitted through the photoelectric conversion unit 20, blue light (B) is absorbed and photoelectrically converted in the photoelectric conversion region 32B, and red light (R) is absorbed and photoelectrically converted in the photoelectric conversion region 32R, respectively. In the photoelectric conversion region 32B, electrons corresponding to the incident blue light (B) are accumulated in the n-region of the photoelectric conversion region 32B, and the accumulated electrons are transferred to the floating diffusion FD2 by the transfer transistor Tr2. Similarly, in the photoelectric conversion region 32R, electrons corresponding to the incident red light (R) are accumulated in the n-region of the photoelectric conversion region 32R, and the accumulated electrons are transferred to the floating diffusion FD3 by the transfer transistor Tr3.

[0108] (1-4. Actions and Effects) The photodetector element 1 of this embodiment is provided with an electron blocking layer 25 composed of multiple layers (e.g., three layers: a first layer 25A, a second layer 25B, and a third layer 25C) between the photoelectric conversion layer 24 and the work function adjustment layer 26. The three layers, the first layer 25A, the second layer 25B, and the third layer 25C, are configured so that their ionization energies become shallower in order from the photoelectric conversion layer 24 side toward the work function adjustment layer 26. This improves the transportability of holes from the photoelectric conversion layer 24 to the interface between the electron blocking layer 25 and the work function adjustment layer 26, and also allows holes to be confined at the interface between the electron blocking layer 25 and the work function adjustment layer 26, thereby improving the charge density at the interface between the electron blocking layer 25 and the work function adjustment layer 26. This will be described below.

[0109] In CMOS image sensors used in electronic devices such as digital still cameras and video cameras, the photodetector elements used as the image sensors constituting each pixel are required to have a good S / N ratio between photocurrent and dark current and a high response speed. For example, in the image sensor described above, a photoelectric conversion layer containing an organic material is provided between a first electrode and a second electrode consisting of a plurality of electrodes arranged opposite each other, and a first semiconductor layer is further provided between the first electrode and the photoelectric conversion layer, and a second semiconductor layer is further provided between the second electrode and the photoelectric conversion layer, thereby improving the image quality.

[0110] In addition, an imaging device has been disclosed in which electrons are read out as signal charges by defining the energy of a work function adjustment layer between a photoelectric conversion layer containing an organic material and a second electrode. For imaging devices that read out electrons as signal charges, improvement in light response is required.

[0111] In contrast to this, in the present embodiment, an electron blocking layer 25 made up of multiple layers (e.g., three layers: a first layer 25A, a second layer 25B, and a third layer 25C) configured so that the ionization energies become shallower in order from the photoelectric conversion layer 24 side toward the work function adjustment layer 26 is provided between the photoelectric conversion layer 24 and the work function adjustment layer 26. This improves the transportability of holes from the photoelectric conversion layer 24 to the interface between the electron blocking layer 25 and the work function adjustment layer 26, and also enables holes to be confined at the interface between the electron blocking layer 25 and the work function adjustment layer 26, thereby improving the charge density at the interface between the electron blocking layer 25 and the work function adjustment layer 26 and promoting recombination.

[0112] As a result, the photodetector element 1 of this embodiment can improve the light response.

[0113] Next, the second and third embodiments, Modifications 1 to 7, application examples, and examples of the present disclosure will be described. In the following, the same components as those in the first embodiment will be assigned the same reference numerals, and their description will be omitted as appropriate.

[0114] 14 illustrates a cross-sectional configuration of a photodetector element (photodetector element 2) according to a second embodiment of the present disclosure. The photodetector element 2 constitutes one pixel (unit pixel P) repeatedly arranged in an array in a pixel section 100A of a photodetector device (e.g., photodetector device 100, see FIG. 29 ) such as a CMOS image sensor used in electronic devices such as digital still cameras and video cameras. In the pixel section 100A, as in the first embodiment, a pixel unit 1a consisting of four unit pixels P arranged in, for example, two rows and two columns serves as a repeating unit, and is repeatedly arranged in an array consisting of row and column directions.

[0115] The photodetector element 2 of this embodiment is configured such that, in a photoelectric conversion section 60 provided on the light incident side S1 of the semiconductor substrate 30, a lower electrode 61 including, for example, a readout electrode 61A and a storage electrode 61B, an insulating layer 62, an oxide semiconductor layer 63, a photoelectric conversion layer 64, an electron blocking layer 65, a work function adjustment layer 66, an electron injection layer 68, and an upper electrode 67 are stacked in this order. The electron injection layer 68 has an electrostatic potential ESP that satisfies the following formula (2): ｍｉｎ (Equation 2) -0.11≦ESP ｍｉｎ ≦−0.09 (2)

[0116] Here, the lower electrode 61 corresponds to a specific example of a "first electrode" according to an embodiment of the present disclosure. The oxide semiconductor layer 63 corresponds to a specific example of an "oxide semiconductor layer" according to an embodiment of the present disclosure. The photoelectric conversion layer 64 corresponds to a specific example of a "photoelectric conversion layer" according to an embodiment of the present disclosure. The electron blocking layer 65 corresponds to a specific example of an "electron blocking layer" according to an embodiment of the present disclosure. The work function adjustment layer 66 corresponds to a specific example of a "work function adjustment layer" according to an embodiment of the present disclosure. The electron injection layer 68 corresponds to a specific example of an "electron injection layer" according to an embodiment of the present disclosure. The upper electrode 67 corresponds to a specific example of a "second electrode" according to an embodiment of the present disclosure.

[0117] (2-1. Configuration of Photodetector) The photodetector 2 is, for example, a so-called vertical spectroscopic photodetector in which one photoelectric conversion unit 60 and two photoelectric conversion regions 32B, 32R are stacked vertically. The photoelectric conversion unit 60 is provided on the back surface (first surface 30A) of the semiconductor substrate 30. The photoelectric conversion regions 32B, 32R are embedded in the semiconductor substrate 30 and stacked in the thickness direction of the semiconductor substrate 30.

[0118] The photoelectric conversion unit 60 and the photoelectric conversion regions 32B and 32R selectively detect light in different wavelength ranges and perform photoelectric conversion. For example, the photoelectric conversion unit 60 acquires a green (G) color signal. The photoelectric conversion regions 32B and 32R acquire blue (B) and red (R) color signals, respectively, due to differences in absorption coefficients. This allows the photodetector element 2 to acquire multiple types of color signals in one pixel without using color filters.

[0119] In this embodiment, a case where electrons, among pairs of electrons and holes (excitons) generated by photoelectric conversion, are read out as signal charges (when an n-type semiconductor region is used as the photoelectric conversion layer) will be described. In addition, in the figures, a "+ (plus)" attached to "p" and "n" indicates that the p-type or n-type impurity concentration is high.

[0120] The surface (second surface 30B) of the semiconductor substrate 30 is provided with, for example, floating diffusions FD1 (region 36B within the semiconductor substrate 30), FD2 (region 37C within the semiconductor substrate 30), and FD3 (region 38C within the semiconductor substrate 30), transfer transistors Tr2 and Tr3, an amplifier transistor (modulation element) AMP, a reset transistor RST, and a selection transistor SEL. The second surface 30B of the semiconductor substrate 30 is further provided with a multilayer wiring layer 40 via a gate insulating layer 33. The multilayer wiring layer 40 has, for example, a configuration in which wiring layers 41 and 4643 are stacked within an insulating layer 44. A vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and input / output terminals 116 (described later) are provided around the periphery of the semiconductor substrate 30, i.e., around the pixel unit 100A.

[0121] 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.

[0122] 15 is a schematic diagram illustrating an example of a detailed cross-sectional configuration of a photoelectric conversion unit 60. The photoelectric conversion unit 60 includes an oxide semiconductor layer 63, a photoelectric conversion layer 64 containing an organic material, an electron blocking layer 65, a work function adjustment layer 66, and an electron injection layer 68 stacked in this order from the lower electrode 61 side between an opposing lower electrode 61 and an upper electrode 67. The electron injection layer 68 is intended to promote electron injection from the upper electrode 67 side, as will be described in detail later. The photoelectric conversion layer 64 includes a p-type semiconductor and an n-type semiconductor, and has a bulk heterojunction structure within the layer. The bulk heterojunction structure is a p / n junction surface formed by mixing a p-type semiconductor and an n-type semiconductor.

[0123] The photoelectric conversion unit 60 further includes an insulating layer 62 between the lower electrode 61 and the oxide semiconductor layer 63. The insulating layer 62 is provided, for example, over the entire surface of the pixel unit 100A, and has an opening 62H above the readout electrode 61A that constitutes the lower electrode 61. The readout electrode 61A is electrically connected to the oxide semiconductor layer 63 through this opening 62H.

[0124] In the photodetector element 2 of this embodiment, light incident on the photoelectric conversion unit 60 from the light incident side S1 is absorbed by the photoelectric conversion layer 64. The excitons thus generated move to the interface between the electron donors and electron acceptors that make up the photoelectric conversion layer 64, where they undergo exciton dissociation, i.e., dissociation into electrons and holes. The carriers (electrons and holes) generated here are transported to different electrodes by diffusion due to differences in carrier concentration and by an internal electric field caused by the difference in work function between the anode (e.g., the upper electrode 67) and the cathode (e.g., the lower electrode 61), and are detected as photocurrent. The transport direction of the electrons and holes can also be controlled by applying a potential between the lower electrode 61 and the upper electrode 67.

[0125] The structure and materials of each part will be described in detail below.

[0126] The photoelectric conversion section 60 is an organic photoelectric conversion element that absorbs, for example, green light corresponding to a part or all of a selective wavelength range (for example, 450 nm or more and 650 nm or less) and generates excitons.

[0127] The lower electrode 61 is composed of, for example, a readout electrode 61A and a storage electrode 61B arranged in parallel on the interlayer insulating layer 29. The readout electrode 61A is for transferring carriers generated in the photoelectric conversion layer 64 to the floating diffusion FD1, and similarly to the first embodiment, one readout electrode 61A is provided for each pixel unit 1a consisting of four unit pixels P arranged in two rows and two columns (see FIG. 2A).

[0128] The configuration of the pixel unit 1a is not limited to this, and for example, two unit pixels P arranged in one row and two columns may be used as the pixel unit 1a, as in the first embodiment (see FIG. 2B ). In this case, one readout electrode 61A is provided between two unit pixels P adjacent to each other in the column direction.

[0129] The readout electrode 61A 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.

[0130] The storage electrode 61B is provided for each unit pixel P to store, as signal charges, electrons, among carriers generated in the photoelectric conversion layer 64, in the oxide semiconductor layer 63. The storage electrode 61B is provided for each unit pixel P in a region that directly faces the light-receiving surfaces of the photoelectric conversion regions 32B and 32R formed in the semiconductor substrate 30 and covers these light-receiving surfaces. The storage electrode 61B is preferably larger than the readout electrode 61A, allowing for the storage of a larger number of carriers. As in the first embodiment, the voltage application unit 56 is connected to the storage electrode 61B via wiring, such as the upper first contact 39C and the upper second contact 39D (see FIG. 6 ).

[0131] The lower electrode 61 is made of, for example, a conductive film having optical transparency. The lower electrode 61 preferably has a work function of 4.0 eV or more and 5.5 eV or less. The material for the lower electrode 61 is, for example, InP doped with tin (Sn). ２ O ３The ITO thin film may have high or low crystallinity (approaching amorphous). In addition to the above, the lower electrode 61 may also be made of a material such as tin oxide (SnO ２ )-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine added as a dopant can be used. Zinc oxide (ZnO) or a zinc oxide-based material with a dopant added can also be used. Examples of ZnO-based materials include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, boron zinc oxide with boron (B) added, and indium zinc oxide (IZO) with indium (In) added. Furthermore, zinc oxide with indium and gallium added as dopants (IGZO, In-GaZnO ４ In addition, the lower electrode 61 may be made of CuI, InSbO ４ , ZnMgO, CuInO ２ , MgIN ２ O ４ , CdO, ZnSnO ３ or TiO ２ Alternatively, spinel oxides or YbFe ２ O ４ Oxides having such a structure may also be used.

[0132] Furthermore, when the lower electrode 61 does not need to be optically transparent (for example, when light is incident from the upper electrode 67 side and the photoelectric conversion regions 32R and 32B are not provided below the storage electrode 61B), a single metal or alloy having a small work function (for example, φ=3.5 eV to 4.5 eV) can be used. Specific examples include alkali metals (for example, lithium (Li), sodium (Na), and potassium (K)) and their fluorides or oxides, and alkaline earth metals (for example, magnesium (Mg) and calcium (Ca)) and their fluorides or oxides. Other examples include rare earth metals such as aluminum (Al), Al—Si—Cu alloys, zinc (Zn), tin (Sn), thallium (Tl), Na—K alloys, Al—Li alloys, Mg—Ag alloys, In, and ytterbium (Yb), or alloys thereof.

[0133] Furthermore, examples of materials for the lower electrode 61 include metals such as platinum (Pt), gold (Au), palladium (Pd), chromium (Cr), nickel (Ni), aluminum (Al), silver (Ag), tantalum (Ta), tungsten (W), copper (Cu), titanium (Ti), indium (In), tin (Sn), iron (Fe), cobalt (Co), and molybdenum (Mo), alloys containing these metal elements, conductive particles made of these metals, conductive particles of alloys containing these metals, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, and graphene. Other examples of materials for the lower electrode 61 include organic materials (conductive polymers) such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT / PSS). Alternatively, the above materials may be mixed with a binder (polymer) to form a paste or ink, which may then be cured and used as an electrode.

[0134] The lower electrode 61 can be formed as a single layer or a laminated film made of the above materials. The film thickness of the lower electrode 61 in the lamination direction (hereinafter simply referred to as thickness) is, for example, 20 nm to 200 nm, and preferably 30 nm to 150 nm.

[0135] The insulating layer 62 serves to electrically separate the storage electrode 61B from the oxide semiconductor layer 63. The insulating layer 62 is provided, for example, on the interlayer insulating layer 29 so as to cover the lower electrode 61. An opening 22H is provided in the insulating layer 62 above the readout electrode 61A of the lower electrode 61, and the readout electrode 61A and the oxide semiconductor layer 63 are electrically connected via this opening 22H. The insulating layer 62 is made of, for example, silicon oxide (SiO ｘ ), silicon nitride (SiN ｘ The insulating layer 62 is made of a single layer film made of one of silicon oxynitride (SiON) and silicon oxynitride (SiON), or a laminated film made of two or more of these materials. The thickness of the insulating layer 62 is, for example, 20 nm to 500 nm.

[0136] The oxide semiconductor layer 63 is for accumulating carriers generated in the photoelectric conversion layer 64. The oxide semiconductor layer 63 can be formed using an oxide semiconductor containing at least one element selected from the group consisting of indium (In), gallium (Ga), zinc (Zn), aluminum (Al), and tin (Sn). In this embodiment, electrons among the carriers generated in the photoelectric conversion layer 64 are used as signal charges. For this reason, the oxide semiconductor layer 63 can be formed using an n-type oxide semiconductor material. Specifically, the oxide semiconductor layer 63 can be formed using an n-type oxide semiconductor material such as IGZO (In—Ga—Zn—O-based oxide semiconductor), gallium oxide (Ga ２ O ３ ), ZTO (Zn—Sn—O-based oxide semiconductor), IZO (In—Zn—O-based oxide semiconductor), ITO, indium gallium aluminum oxide (InGaAlO), indium gallium silicon oxide (InGaSiO), etc. The thickness of the oxide semiconductor layer 63 is, for example, 10 nm to 300 nm.

[0137] The photoelectric conversion layer 64 converts light energy into electrical energy. The photoelectric conversion layer 64 is configured, for example, by including two or more organic materials (p-type semiconductor materials or n-type semiconductor materials) that function as p-type or n-type semiconductors, respectively. The photoelectric conversion layer 64 has a junction surface (p / n junction surface) between a p-type semiconductor material and an n-type semiconductor material within the layer. The p-type semiconductor functions relatively as an electron donor, and the n-type semiconductor functions relatively as an electron acceptor. The photoelectric conversion layer 64 provides a site where excitons generated upon light absorption separate into electrons and holes. Specifically, the excitons separate into electrons and holes at the interface (p / n junction surface) between the electron donor and electron acceptor.

[0138] In addition to the p-type and n-type semiconductor materials, the photoelectric conversion layer 64 may also contain an organic material, a so-called dye material, that photoelectrically converts light in a predetermined wavelength range while transmitting light in other wavelength ranges. When the photoelectric conversion layer 64 is formed using three types of organic materials, i.e., a p-type semiconductor material, an n-type semiconductor material, and a dye material, the p-type and n-type semiconductor materials are preferably materials that are optically transparent in the visible range (e.g., 450 nm to 800 nm). The thickness of the photoelectric conversion layer 64 is, for example, 50 nm to 500 nm.

[0139] Examples of organic materials that can be used to form the photoelectric conversion layer 64 include quinacridone derivatives, naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, and fluoranthene derivatives. The photoelectric conversion layer 64 is formed by combining two or more of the above organic materials. Depending on the combination, the above organic materials function as p-type or n-type semiconductors.

[0140] The organic material constituting the photoelectric conversion layer 64 is not particularly limited. In addition to the above organic materials, for example, polymers of phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, and the like, or derivatives thereof, can be used. Alternatively, metal complex dyes, cyanine dyes, merocyanine dyes, phenylxanthene dyes, triphenylmethane dyes, rhodacyanine dyes, xanthene dyes, macrocyclic azaannulene dyes, azulene dyes, naphthoquinone dyes, anthraquinone dyes, condensed polycyclic aromatic compounds such as pyrene, chain compounds in which aromatic rings or heterocyclic compounds are condensed, quinoline having a squarylium group and a croconite methine group as a bonding chain, two nitrogen-containing heterocycles such as benzothiazole and benzoxazole, or cyanine-like dyes bonded by a squarylium group and a croconite methine group, can be used. Examples of the metal complex dye include dithiol metal complex dyes, metal phthalocyanine dyes, metal porphyrin dyes, and ruthenium complex dyes. Of these, ruthenium complex dyes are particularly preferred, but the invention is not limited to these.

[0141] The electron blocking layer 65 serves to prevent injection of electrons from the upper electrode 67 side and to efficiently transport holes, among carriers generated in the photoelectric conversion layer 64, to the interface between the electron blocking layer 65 and the work function adjustment layer 66. The electron blocking layer 65 has a configuration in which, for example, a plurality of layers (for example, three layers: a first layer 25A, a second layer 25B, and a third layer 25C) are stacked, and each layer has a cascade structure in which the ionization energy becomes shallower in order from the photoelectric conversion layer 64 side toward the work function adjustment layer 66, as in the first embodiment. Specifically, the electron blocking layer 65 is made up of n layers, including a first electron blocking layer adjacent to the photoelectric conversion layer, an nth electron blocking layer adjacent to the work function adjustment layer, and an (n-1)th electron blocking layer adjacent to the nth electron blocking layer on the opposite side to the work function adjustment layer, and the ionization energy of the photoelectric conversion layer 64 is reduced to IP １ , the ionization energy of the first electron blocking layer is IP ２ , the ionization energy of the (n-1)th electron blocking layer is IP ｎ－１, the ionization energy of the nth electron blocking layer is IP ｎ and the electron affinity of the work function adjusting layer 66 is EA ｗ When the electron blocking layer 65 is set as above, each layer of the electron blocking layer 65 is configured to satisfy the following formula (3): ｗ <IP ｎ ≦IP ｎ－１ +0.03 ... (3)

[0142] 16 , in the electron blocking layer 65, the first layer 65A adjacent to the photoelectric conversion layer 64 has an ionization energy shallower than that of the photoelectric conversion layer 64, and the third layer 65C adjacent to the work function adjustment layer 66 has an ionization energy deeper than the electron affinity (or work function) of the work function adjustment layer 66. Of the first layer 65A, second layer 65B, and third layer 65C constituting the electron blocking layer 65, the first layer 65A has the largest ionization energy, the third layer 65C has the smallest ionization energy, and the second layer 65B has an ionization energy between that of the first layer 65A and the third layer 65C. There is an energy difference of 0.03 eV or more between the ionization energies of the third layer 65C adjacent to the work function adjustment layer 66 and the second layer 65B adjacent to the third layer 65C on the opposite side of the work function adjustment layer 66.

[0143] As a result, holes generated in the photoelectric conversion layer 64 are efficiently transported to the interface between the electron blocking layer 65 and the work function adjustment layer 66, improving the charge density at the interface between the electron blocking layer 65 (here, the third layer 65C) and the work function adjustment layer 66, and promoting the recombination of electrons and holes at the interface between the electron blocking layer 65 and the work function adjustment layer 66. This reduces residual charges in the photoelectric conversion layer 64 and the electron blocking layer 65, improving photoresponsiveness, such as improving afterimage characteristics.

[0144] The electron blocking layer 65 does not necessarily have to have a multi-layer structure, but may be a single layer.

[0145] The electron blocking layer 65 includes an organic material. Examples of the material for the electron blocking layer 65 include thienoacene-based materials such as naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, quinacridone derivatives, thiophene derivatives, thienothiophene derivatives, benzothiophene derivatives, benzothienobenzothiophene (BTBT) derivatives, dinaphthothienothiophene (DNTT) derivatives, benzobisbenzothiophene (BBBT) derivatives, thienobisbenzothiophene (TBBT) derivatives, dibenzothienobisbenzothiophene (DBTBT) derivatives, dithienobenzodithiophene (DTBDT) derivatives, dibenzothienodithiophene (DBTDT) derivatives, benzodithiophene (BDT) derivatives, naphthodithiophene (NDT) derivatives, and anthracenodithiophene (ADT) derivatives. Other examples of p-type semiconductors include fluorene derivatives, triphenylene derivatives, triphenylamine derivatives, carbazole derivatives, picene derivatives, and chrysene derivatives.

[0146] The electron blocking layer 65 has a total thickness of, for example, 3 nm to 200 nm, and preferably, for example, 10 nm to 100 nm. Each of the layers constituting the electron blocking layer 65 (for example, the first layer 65A, the second layer 65B, and the third layer 65C) has a thickness of, for example, 3 nm to 100 nm.

[0147] The work function adjustment layer 66 has a larger electron affinity or work function than the work function of the upper electrode 67, and improves the electrical connection between the electron blocking layer 65 and the upper electrode 67. Examples of materials that constitute the work function adjustment layer 66 include dipyrazino[2,3-f:2',3'v-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN). Other examples of materials that constitute the work function adjustment layer 66 include PEDOT / PSS and polyaniline, and MoO ｘ , RuO ｘ , V.O. ｘ and W.O. ｘ and the like metal oxides.

[0148] The electron injection layer 68 is intended to promote the injection of electrons from the upper electrode 67 side. As shown in FIG. 16, the electron injection layer 68 has a shallower electron affinity (or work function) than the adjacent work function adjustment layer 66. The electron injection layer 68 has an electrostatic potential ESP that indicates nucleophilicity. ｍｉｎ is configured to satisfy the above formula (2). ｍｉｎ can be determined from density functional theory (DFT) calculations.

[0149] This improves the injection of electrons from the upper electrode 67, further improving the charge density at the interface between the electron blocking layer 65 (here, the third layer 65C) and the work function adjustment layer 66, and further promoting the recombination of electrons and holes at the interface between the electron blocking layer 65 and the work function adjustment layer 66. This reduces residual charges in the photoelectric conversion layer 64 and the electron blocking layer 65, further improving photoresponsiveness, such as improving afterimage characteristics.

[0150] The electron injection layer 68 contains an organic material and has a film thickness of, for example, 3 nm to 200 nm.

[0151] The upper electrode 67 is made of, for example, a light-transmitting conductive film, similar to the lower electrode 61. The upper electrode 67 is made of, for example, InP doped with tin (Sn). ２ O ３ The crystallinity of the ITO thin film may be high or low (approaching amorphous). In addition to the above, the upper electrode 67 may also be made of tin oxide (SnO ２)-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine added as a dopant. Zinc oxide (ZnO) or zinc oxide-based materials with dopants added may also be used. Examples of ZnO-based materials include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, boron zinc oxide with boron (B) added, and indium zinc oxide (IZO) with indium (In) added. Furthermore, zinc oxide with indium and gallium added as dopants (IGZO, In-GaZnO4) may also be used. In addition, materials constituting the lower electrode 61 include CuI, InSbO ４ , ZnMgO, CuInO ２ , MgIN ２ O ４ , CdO, ZnSnO ３ or TiO ２ Alternatively, spinel oxides or YbFe ２ O ４ Oxides having such a structure may also be used.

[0152] Furthermore, if optical transparency is not required for the upper electrode 67, a single metal or alloy having a large work function (for example, φ=4.5 eV to 5.5 eV) can be used. Specific examples include Au, Ag, Cr, Ni, Pd, Pt, Fe, iridium (Ir), germanium (Ge), osmium (Os), rhenium (Re), tellurium (Te), and alloys thereof.

[0153] Furthermore, examples of materials that can be used to form the upper electrode 67 include metals such as Pt, Au, Pd, Cr, Ni, Al, Ag, Ta, W, Cu, Ti, In, Sn, Fe, Co, and Mo, alloys containing these metal elements, conductive particles made of these metals, conductive particles of alloys containing these metals, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, and graphene. Other examples of materials that can be used to form the upper electrode 67 include organic materials (conductive polymers) such as PEDOT / PSS. Alternatively, the above materials can be mixed with a binder (polymer) to form a paste or ink, which can then be hardened and used as an electrode.

[0154] The upper electrode 67 can be formed as a single layer or a laminated film made of the above materials. The thickness of the upper electrode 67 is, for example, 20 nm to 200 nm, preferably 30 nm to 150 nm.

[0155] The photoelectric conversion unit 60 may have other layers provided between the lower electrode 61 and the photoelectric conversion layer 64 and between the photoelectric conversion layer 64 and the upper electrode 67. The photoelectric conversion layer 64 may have a pin bulk heterostructure in which, for example, a p-type blocking layer, a layer containing a p-type semiconductor and an n-type semiconductor (i-layer), and an n-type blocking layer are stacked.

[0156] (2-2. Actions and Effects) In the photodetector element 2 of this embodiment, an electrostatic potential ESP that satisfies the above formula (2) is generated between the work function adjustment layer 66 and the upper electrode 67. ｍｉｎ As a result, the injection of electrons from the upper electrode 67 is improved, and the charge density at the interface between the electron blocking layer 65 and the work function adjusting layer 66 is improved.

[0157] As described above, in the photodetector element 2 of this embodiment, it is possible to improve the light response, similarly to the first embodiment.

[0158] Furthermore, in this embodiment, an electron blocking layer 65 is provided between the photoelectric conversion layer 64 and the work function adjustment layer 66. The electron blocking layer 65 is made up of multiple layers (e.g., three layers: a first layer 65A, a second layer 65B, and a third layer 65C) configured so that the ionization energies become shallower in this order from the photoelectric conversion layer 64 side toward the work function adjustment layer 66. This improves the transportability of holes from the photoelectric conversion layer 64 to the interface between the electron blocking layer 65 and the work function adjustment layer 66, and also allows holes to be confined at the interface between the electron blocking layer 65 and the work function adjustment layer 66, thereby further improving the charge density at the interface between the electron blocking layer 65 and the work function adjustment layer 66. This makes it possible to further improve the photoresponsiveness.

[0159] 17 illustrates a cross-sectional configuration of a photodetector element (photodetector element 3) according to a third embodiment of the present disclosure. The photodetector element 3 constitutes one pixel (unit pixel P) repeatedly arranged in an array in a pixel section 100A of a photodetector device (e.g., photodetector device 100, see FIG. 29 ) such as a CMOS image sensor used in electronic devices such as digital still cameras and video cameras. In the pixel section 100A, as in the first embodiment, a pixel unit 1a consisting of four unit pixels P arranged in, for example, two rows and two columns serves as a repeating unit, and is repeatedly arranged in an array consisting of row and column directions.

[0160] The photodetector element 3 of this embodiment includes a photoelectric conversion unit 70 provided on the light incident side S1 of the semiconductor substrate 30, in which a lower electrode 71 including a readout electrode 71A and a storage electrode 71B, an insulating layer 72, an oxide semiconductor layer 73, a photoelectric conversion layer 74, an intermediate layer 75, and an upper electrode 76 are stacked in this order. The intermediate layer 75 has a minimum binding energy Eb １ Alternatively, the intermediate layer 75 has a minimum binding energy Eb １ , the nth lowest binding energy Eb ｎ (n≧2) and the n+1 lowest n+1 binding energy Eb ｎ＋１ (n≧2), and the nth binding energy Eb ｎ, the n+1th bond energy Eb ｎ＋１ and the electron affinity change ΔEA when all bonds from the lowest bond energy to the nth bond energy are dissociated and replaced with hydrogen. ｎ satisfies the following formulas (5), (6), and (7). (Formula 6) −5.33 eV<Eb １ <8.67eV (4) (Math. 7) Eb ｎ ≦5.33eV (5) 5.33eV<Eb ｎ＋１ <8.67eV...(6) ΔEA ｎ <0.3 (7)

[0161] Here, the lower electrode 71 corresponds to a specific example of a "first electrode" according to an embodiment of the present disclosure. The oxide semiconductor layer 73 corresponds to a specific example of an "oxide semiconductor layer" according to an embodiment of the present disclosure. The photoelectric conversion layer 74 corresponds to a specific example of a "photoelectric conversion layer" according to an embodiment of the present disclosure. The intermediate layer 75 corresponds to a specific example of a "first intermediate layer" or a "second intermediate layer" according to an embodiment of the present disclosure. The upper electrode 76 corresponds to a specific example of a "second electrode" according to an embodiment of the present disclosure.

[0162] (3-1. Configuration of Photodetector) The photodetector 3 is, for example, a so-called vertical spectroscopic photodetector in which one photoelectric conversion unit 70 and two photoelectric conversion regions 32B, 32R are stacked vertically. The photoelectric conversion unit 70 is provided on the back surface (first surface 30A) of the semiconductor substrate 30. The photoelectric conversion regions 32B, 32R are embedded in the semiconductor substrate 30 and stacked in the thickness direction of the semiconductor substrate 30.

[0163] The photoelectric conversion unit 70 and the photoelectric conversion regions 32B and 32R selectively detect light in different wavelength ranges and perform photoelectric conversion. For example, the photoelectric conversion unit 70 acquires a green (G) color signal. The photoelectric conversion regions 32B and 32R acquire blue (B) and red (R) color signals, respectively, due to differences in absorption coefficients. This allows the photodetector 3 to acquire multiple types of color signals in one pixel without using color filters.

[0164] In this embodiment, a case where electrons, among pairs of electrons and holes (excitons) generated by photoelectric conversion, are read out as signal charges (when an n-type semiconductor region is used as the photoelectric conversion layer) will be described. In addition, in the figures, a "+ (plus)" attached to "p" and "n" indicates that the p-type or n-type impurity concentration is high.

[0165] The surface (second surface 30B) of the semiconductor substrate 30 is provided with, for example, floating diffusions FD1 (region 36B within the semiconductor substrate 30), FD2 (region 37C within the semiconductor substrate 30), and FD3 (region 38C within the semiconductor substrate 30), transfer transistors Tr2 and Tr3, an amplifier transistor (modulation element) AMP, a reset transistor RST, and a selection transistor SEL. The second surface 30B of the semiconductor substrate 30 is further provided with a multilayer wiring layer 40 via a gate insulating layer 33. The multilayer wiring layer 40 has, for example, a configuration in which wiring layers 41 and 4643 are stacked within an insulating layer 44. A vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and input / output terminals 116 (described later) are provided around the periphery of the semiconductor substrate 30, i.e., around the pixel unit 100A.

[0166] 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.

[0167] FIG. 18 is a schematic diagram of an example of a detailed cross-sectional configuration of the photoelectric conversion unit 70 (photoelectric conversion unit 70A). FIG. 20 is a schematic diagram of another example of a detailed cross-sectional configuration of the photoelectric conversion unit 70 (photoelectric conversion unit 70B). The photoelectric conversion unit 70 includes an oxide semiconductor layer 73, a photoelectric conversion layer 74 containing an organic material, and an intermediate layer 75 stacked in this order from the lower electrode 71 side between an opposing lower electrode 71 and an upper electrode 76. As will be described in detail later, the intermediate layer 75 is intended to suppress the formation of an interfacial barrier that may occur in the layer directly below the upper electrode 76 when the upper electrode 76 is formed. The photoelectric conversion layer 74 is composed of a p-type semiconductor and an n-type semiconductor and has a bulk heterojunction structure within the layer. The bulk heterojunction structure is a p / n junction surface formed by mixing p-type and n-type semiconductors.

[0168] The photoelectric conversion unit 70 further includes an insulating layer 72 between the lower electrode 71 and the oxide semiconductor layer 73. The insulating layer 72 is provided, for example, over the entire surface of the pixel unit 100A, and has an opening 62H above the readout electrode 71A that constitutes the lower electrode 71. The readout electrode 71A is electrically connected to the oxide semiconductor layer 73 through this opening 62H.

[0169] In the photodetector element 3 of this embodiment, light incident on the photoelectric conversion unit 70 from the light incident side S1 is absorbed by the photoelectric conversion layer 74. The excitons thus generated migrate to the interface between the electron donors and electron acceptors that make up the photoelectric conversion layer 74, where they undergo exciton dissociation, i.e., dissociation into electrons and holes. The carriers (electrons and holes) generated here are transported to different electrodes by diffusion due to differences in carrier concentration and by an internal electric field caused by the difference in work function between the anode (e.g., the upper electrode 76) and the cathode (e.g., the lower electrode 71), and are detected as photocurrent. The transport direction of the electrons and holes can also be controlled by applying a potential between the lower electrode 71 and the upper electrode 76.

[0170] The structure and materials of each part will be described in detail below.

[0171] The photoelectric conversion section 70 is an organic photoelectric conversion element that absorbs, for example, green light corresponding to a part or all of a selective wavelength range (for example, 450 nm or more and 650 nm or less) and generates excitons.

[0172] The lower electrode 71 is composed of, for example, a readout electrode 71A and a storage electrode 71B arranged in parallel on the interlayer insulating layer 29. The readout electrode 71A is for transferring carriers generated in the photoelectric conversion layer 74 to the floating diffusion FD1, and, as in the first embodiment, one readout electrode 71A is provided for each pixel unit 1a consisting of four unit pixels P arranged in two rows and two columns (see FIG. 2A).

[0173] The configuration of the pixel unit 1a is not limited to this, and for example, two unit pixels P arranged in one row and two columns may be used as the pixel unit 1a, as in the first embodiment (see FIG. 2B ). In this case, one readout electrode 71A is provided between two unit pixels P adjacent to each other in the column direction.

[0174] The read electrode 71A 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.

[0175] The storage electrode 71B is provided for each unit pixel P to store, as signal charges, electrons, among carriers generated in the photoelectric conversion layer 74, in the oxide semiconductor layer 73. The storage electrode 71B is provided for each unit pixel P in a region that directly faces the light-receiving surfaces of the photoelectric conversion regions 32B and 32R formed in the semiconductor substrate 30 and covers these light-receiving surfaces. The storage electrode 71B is preferably larger than the readout electrode 71A, allowing for the storage of a larger number of carriers. As in the first embodiment, the voltage application unit 56 is connected to the storage electrode 71B via wiring, such as the upper first contact 39C and the upper second contact 39D (see FIG. 6 ).

[0176] The lower electrode 71 is made of, for example, a conductive film having optical transparency. The lower electrode 71 preferably has a work function of 4.0 eV or more and 5.5 eV or less. The material of the lower electrode 71 is, for example, InP doped with tin (Sn). ２ O ３ The ITO thin film may have high or low crystallinity (approaching amorphous). In addition to the above, the lower electrode 71 may also be made of a material such as tin oxide (SnO ２ )-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine added as a dopant can be used. Zinc oxide (ZnO) or a zinc oxide-based material with a dopant added can also be used. Examples of ZnO-based materials include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, boron zinc oxide with boron (B) added, and indium zinc oxide (IZO) with indium (In) added. Furthermore, zinc oxide with indium and gallium added as dopants (IGZO, In-GaZnO ４ In addition, the lower electrode 71 may be made of CuI, InSbO ４ , ZnMgO, CuInO ２ , MgIN ２ O ４ , CdO, ZnSnO ３ or TiO ２ Alternatively, spinel oxides or YbFe ２ O ４ Oxides having such a structure may also be used.

[0177] Furthermore, when the lower electrode 71 does not need to be optically transparent (for example, when light is incident from the upper electrode 76 side and the photoelectric conversion regions 32R and 32B are not provided below the storage electrode 71B), a single metal or alloy having a small work function (for example, φ=3.5 eV to 4.5 eV) can be used. Specific examples include alkali metals (for example, lithium (Li), sodium (Na), and potassium (K)) and their fluorides or oxides, and alkaline earth metals (for example, magnesium (Mg) and calcium (Ca)) and their fluorides or oxides. Other examples include rare earth metals such as aluminum (Al), Al—Si—Cu alloys, zinc (Zn), tin (Sn), thallium (Tl), Na—K alloys, Al—Li alloys, Mg—Ag alloys, In, and ytterbium (Yb), or alloys thereof.

[0178] Furthermore, examples of materials that can be used to form the lower electrode 71 include metals such as platinum (Pt), gold (Au), palladium (Pd), chromium (Cr), nickel (Ni), aluminum (Al), silver (Ag), tantalum (Ta), tungsten (W), copper (Cu), titanium (Ti), indium (In), tin (Sn), iron (Fe), cobalt (Co), and molybdenum (Mo), alloys containing these metal elements, conductive particles made of these metals, conductive particles of alloys containing these metals, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, and graphene. Other examples of materials that can be used to form the lower electrode 71 include organic materials (conductive polymers) such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT / PSS). Alternatively, the above materials can be mixed with a binder (polymer) to form a paste or ink, which can then be cured and used as an electrode.

[0179] The lower electrode 71 can be formed as a single layer or a laminated film made of the above materials. The film thickness of the lower electrode 71 in the lamination direction (hereinafter simply referred to as thickness) is, for example, 20 nm to 200 nm, and preferably 30 nm to 150 nm.

[0180] The insulating layer 72 serves to electrically separate the storage electrode 71B from the oxide semiconductor layer 73. The insulating layer 72 is provided, for example, on the interlayer insulating layer 29 so as to cover the lower electrode 71. An opening 22H is provided in the insulating layer 72 above the readout electrode 71A of the lower electrode 71, and the readout electrode 71A and the oxide semiconductor layer 73 are electrically connected via this opening 22H. The insulating layer 72 is made of, for example, silicon oxide (SiO ｘ ), silicon nitride (SiN ｘ The insulating layer 72 is made of a single layer film made of one of silicon oxynitride (SiON) and silicon oxynitride (SiON), or a laminated film made of two or more of these materials. The thickness of the insulating layer 72 is, for example, 20 nm to 500 nm.

[0181] The oxide semiconductor layer 73 is for accumulating carriers generated in the photoelectric conversion layer 74. The oxide semiconductor layer 73 can be formed using an oxide semiconductor containing at least one element selected from the group consisting of indium (In), gallium (Ga), zinc (Zn), aluminum (Al), and tin (Sn). In this embodiment, electrons among the carriers generated in the photoelectric conversion layer 74 are used as signal charges. For this reason, the oxide semiconductor layer 73 can be formed using an n-type oxide semiconductor material. Specifically, the oxide semiconductor layer 73 can be formed using an n-type oxide semiconductor material such as IGZO (In—Ga—Zn—O-based oxide semiconductor), gallium oxide (Ga ２ O ３ ), ZTO (Zn—Sn—O-based oxide semiconductor), IZO (In—Zn—O-based oxide semiconductor), ITO, indium gallium aluminum oxide (InGaAlO), indium gallium silicon oxide (InGaSiO), etc. The thickness of the oxide semiconductor layer 73 is, for example, 10 nm to 300 nm.

[0182] The photoelectric conversion layer 74 converts light energy into electrical energy. The photoelectric conversion layer 74 is configured, for example, by including two or more organic materials (p-type semiconductor materials or n-type semiconductor materials) that function as p-type or n-type semiconductors, respectively. The photoelectric conversion layer 74 has a junction surface (p / n junction surface) between a p-type semiconductor material and an n-type semiconductor material within the layer. The p-type semiconductor functions relatively as an electron donor, and the n-type semiconductor functions relatively as an electron acceptor. The photoelectric conversion layer 74 provides a site where excitons generated upon light absorption separate into electrons and holes. Specifically, the excitons separate into electrons and holes at the interface (p / n junction surface) between the electron donor and electron acceptor.

[0183] In addition to the p-type and n-type semiconductor materials, the photoelectric conversion layer 74 may also contain an organic material, a so-called dye material, that photoelectrically converts light in a predetermined wavelength range while transmitting light in other wavelength ranges. When the photoelectric conversion layer 74 is formed using three types of organic materials, i.e., a p-type semiconductor material, an n-type semiconductor material, and a dye material, the p-type and n-type semiconductor materials are preferably materials that are optically transparent in the visible range (e.g., 450 nm to 800 nm). The thickness of the photoelectric conversion layer 74 is, for example, 50 nm to 500 nm.

[0184] Examples of organic materials that can be used to form the photoelectric conversion layer 74 include quinacridone derivatives, naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, and fluoranthene derivatives. The photoelectric conversion layer 74 is formed by combining two or more of the above organic materials. Depending on the combination, the above organic materials function as p-type or n-type semiconductors.

[0185] The organic material constituting the photoelectric conversion layer 74 is not particularly limited. In addition to the above organic materials, for example, polymers of phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, and the like, or derivatives thereof, can be used. Alternatively, metal complex dyes, cyanine dyes, merocyanine dyes, phenylxanthene dyes, triphenylmethane dyes, rhodacyanine dyes, xanthene dyes, macrocyclic azaannulene dyes, azulene dyes, naphthoquinone dyes, anthraquinone dyes, condensed polycyclic aromatic compounds such as pyrene, linear compounds in which aromatic rings or heterocyclic compounds are condensed, quinoline having a squarylium group and a croconite methine group as a bonding chain, two nitrogen-containing heterocycles such as benzothiazole and benzoxazole, or cyanine-like dyes bonded by a squarylium group and a croconite methine group, can be used. Examples of the metal complex dye include dithiol metal complex dyes, metal phthalocyanine dyes, metal porphyrin dyes, and ruthenium complex dyes. Of these, ruthenium complex dyes are particularly preferred, but the invention is not limited to these.

[0186] As described above, the intermediate layer 75 suppresses the formation of an interface barrier in the layer immediately below where the upper electrode 76 is formed when the upper electrode 76 is formed. The intermediate layer 75 has an electron affinity EA that changes by less than 0.3 eV even when a bond having a bond energy of 5.33 eV or less is dissociated. Such an intermediate layer 75 has a minimum bond energy Eb that satisfies the above formula (4). １ Alternatively, the intermediate layer 75 has a minimum binding energy Eb １ , the nth lowest binding energy Eb ｎ (n≧2) and the n+1 lowest n+1 binding energy Eb ｎ＋１ (n≧2), and the nth binding energy Eb ｎ , the n+1th bond energy Eb ｎ＋１ and the electron affinity change ΔEA when all bonds from the lowest bond energy to the nth bond energy are dissociated and replaced with hydrogen. ｎ satisfies the above formulas (5), (6), and (7).

[0187] The intermediate layer 75 can be, for example, a work function adjustment layer 75A as shown in Fig. 18. Fig. 19 shows the relationship between the energy levels of the layers of the photoelectric conversion section 70A shown in Fig. 18. The work function adjustment layer 75A, which functions as the intermediate layer 75, adjusts the work function WF ｃ Electron affinity EA greater than ｗ and further configured so that the minimum bond energy satisfies the above formula (4), or so that the above formulas (5), (6), and (7) are satisfied so that the energy change is small even when the bond is dissociated.

[0188] 20, the intermediate layer 75 can be a protective layer 75B. FIG. 21 shows the relationship between the energy levels of the layers of the photoelectric conversion section 70B shown in FIG. 20. The protective layer 75B, which functions as the intermediate layer 75, has a work function WF Ａ Electron affinity EA greater than ｗ and further configured so that the minimum bond energy satisfies the above formula (4), or so that the above formulas (5), (6), and (7) are satisfied so that the energy change is small even when the bond is dissociated.

[0189] The protective layer 75B is formed of the nucleophilic electrostatic potential ESP described in the second embodiment. ｍｉｎ The electron injection layer 68 may be one that satisfies the above formula (2).

[0190] The intermediate layer 75 has a thickness of, for example, 3 nm or more and 200 nm or less, and preferably has a thickness of, for example, 5 nm or more and 50 nm or less.

[0191] The upper electrode 76 is made of, for example, a light-transmitting conductive film, similar to the lower electrode 71. The upper electrode 76 is made of, for example, InP doped with tin (Sn). ２ O ３The crystallinity of the ITO thin film may be high or low (approaching amorphous). In addition to the above, the upper electrode 76 may also be made of tin oxide (SnO ２ )-based materials, for example, ATO with Sb added as a dopant, and FTO with fluorine added as a dopant. Zinc oxide (ZnO) or a zinc oxide-based material with a dopant added thereto may also be used. Examples of ZnO-based materials include aluminum zinc oxide (AZO) with aluminum (Al) added as a dopant, gallium zinc oxide (GZO) with gallium (Ga) added, boron zinc oxide with boron (B) added, and indium zinc oxide (IZO) with indium (In) added. Furthermore, zinc oxide with indium and gallium added as dopants (IGZO, In-GaZnO4) may also be used. In addition, materials constituting the lower electrode 71 include CuI, InSbO ４ , ZnMgO, CuInO ２ , MgIN ２ O ４ , CdO, ZnSnO ３ or TiO ２ Alternatively, spinel oxides or YbFe ２ O ４ Oxides having such a structure may also be used.

[0192] Furthermore, if optical transparency is not required for the upper electrode 76, a single metal or alloy having a large work function (for example, φ=4.5 eV to 5.5 eV) can be used. Specific examples include Au, Ag, Cr, Ni, Pd, Pt, Fe, iridium (Ir), germanium (Ge), osmium (Os), rhenium (Re), tellurium (Te), and alloys thereof.

[0193] Examples of materials that can be used to form the upper electrode 76 include metals such as Pt, Au, Pd, Cr, Ni, Al, Ag, Ta, W, Cu, Ti, In, Sn, Fe, Co, and Mo, alloys containing these metal elements, conductive particles made of these metals, conductive particles of alloys containing these metals, polysilicon containing impurities, carbon-based materials, oxide semiconductors, carbon nanotubes, and graphene. Other examples of materials that can be used to form the upper electrode 76 include organic materials (conductive polymers) such as PEDOT / PSS. Alternatively, the above materials can be mixed with a binder (polymer) to form a paste or ink, which can then be cured and used as an electrode.

[0194] The upper electrode 76 can be formed as a single layer or a laminated film made of the above materials. The thickness of the upper electrode 76 is, for example, 20 nm to 200 nm, preferably 30 nm to 150 nm.

[0195] The photoelectric conversion unit 70 may have other layers provided between the lower electrode 71 and the photoelectric conversion layer 74 and between the photoelectric conversion layer 74 and the upper electrode 76. The photoelectric conversion layer 74 may have a pin bulk heterostructure in which, for example, a p-type blocking layer, a layer containing a p-type semiconductor and an n-type semiconductor (i-layer), and an n-type blocking layer are stacked.

[0196] (3-2. Actions and Effects) In the photodetector element 3 of this embodiment, the intermediate layer 75 that satisfies the above formula (4) or the above formulas (5), (6), and (7) is provided directly below the upper electrode 76. This suppresses the formation of an interface barrier that may occur in the layer directly below where the upper electrode 76 is formed, for example, when the upper electrode 76 is formed by sputtering.

[0197] As a result, the photodetector element 3 of this embodiment can improve the light response.

[0198] 4. Modifications (4-1. Modification 1) FIG. 22A is a schematic diagram illustrating a cross-sectional configuration of a photodetector element 4A according to Modification 1 of the present disclosure. FIG. 22B is a schematic diagram illustrating an example of the planar configuration of the photodetector element 4A illustrated in FIG. 22A , where FIG. 22A illustrates a cross section taken along line II-II in FIG. 22B . The photodetector element 4A is, for example, a stacked photodetector element in which a photoelectric conversion region 32 and a photoelectric conversion unit (e.g., the photoelectric conversion unit 20 of the first embodiment) are stacked. In a pixel unit 100A of a photodetector device (e.g., the photodetector device 100) including this photodetector element 4A, pixel units 1a each consisting of four unit pixels P arranged in two rows and two columns are repeated in an array formed in the row and column directions, as illustrated in FIG. 22B .

[0199] In the photodetector element 4A of this modification, a color filter 55 that selectively transmits red light (R), green light (G), and blue light (B) is provided for each unit pixel P above the photoelectric conversion section 20 (on the light incident side S1). Specifically, in a pixel unit 1a consisting of four unit pixels P arranged in two rows and two columns, two color filters (green color filters) that selectively transmit green light (G) are arranged diagonally, and one color filter (red color filter and blue color filter) that selectively transmit red light (R) and blue light (B) is arranged on each diagonal that is perpendicular to the pixel unit 1a. In the unit pixels (Pr, Pg, Pb) provided with color filters of each color, the photoelectric conversion section 20 detects the corresponding color light, for example. That is, in the pixel section 100A, the unit pixels (Pr, Pg, Pb) that detect red light (R), green light (G), and blue light (B), respectively, are arranged in a Bayer pattern.

[0200] The photoelectric conversion unit 20 absorbs light corresponding to some or all of the wavelengths in the visible light region of, for example, 400 nm or more and less than 750 nm, and generates excitons (electron-hole pairs), and is composed of a lower electrode 21, an insulating layer (insulating layer 22), an oxide semiconductor layer 23, a photoelectric conversion layer 24, an electron blocking layer 25 consisting of multiple layers, a work function adjustment layer 26, and an upper electrode 27 stacked in this order.

[0201] The photoelectric conversion region 32 detects, for example, an infrared light region of 750 nm or more and 1300 nm or less.

[0202] In the photodetector element 4A, light in the visible light region (red light (R), green light (G), and blue light (B)) that passes through the color filter 55 is absorbed by the photoelectric conversion unit 20 of the unit pixels (Pr, Pg, Pb) that are provided with the respective color filters, while other light, for example, light in the infrared light region (e.g., 750 nm or more and 1000 nm or less) (infrared light (IR)), passes through the photoelectric conversion unit 20. The infrared light (IR) that passes through the photoelectric conversion unit 20 is detected in the photoelectric conversion region 32 of each unit pixel Pr, Pg, Pb, and signal charges corresponding to the infrared light (IR) are generated in each unit pixel Pr, Pg, Pb. In other words, a photodetector device 100 including the photodetector element 4A is capable of simultaneously generating both visible light images and infrared light images.

[0203] Furthermore, the photodetector device 100 including the photodetector element 4A can acquire a visible light image and an infrared light image at the same position in the XY plane, thereby enabling high integration in the XY plane.

[0204] (4-2. Modification 2) Figure 23A is a schematic diagram illustrating a cross-sectional configuration of a photodetector 4B according to Modification 2 of the present disclosure. Figure 23B is a schematic diagram illustrating an example of the planar configuration of the photodetector 4B illustrated in Figure 23A, and Figure 23A illustrates a cross section taken along line III-III illustrated in Figure 23B. While the above-described modification 1 illustrates an example in which the color filter 55 is provided above the photoelectric conversion unit 20 (on the light incident side S1), the color filter 55 may be provided, for example, between the photoelectric conversion region 32 and the photoelectric conversion unit 20, as illustrated in Figure 23A.

[0205] In the photodetector element 4B, for example, the color filter 55 has a configuration in which a color filter (color filter 55R) that selectively transmits at least red light (R) and a color filter (color filter 55B) that selectively transmits at least blue light (B) are arranged diagonally opposite each other within the pixel unit 1a. The photoelectric conversion unit 20 (photoelectric conversion layer 24) is configured to selectively absorb light having a wavelength corresponding to, for example, green light (G). The photoelectric conversion region 32R selectively absorbs light having a wavelength corresponding to red light (R), and the photoelectric conversion region 32B selectively absorbs light having a wavelength corresponding to blue light (B). This makes it possible to obtain signals corresponding to red light (R) or blue light (B) in the photoelectric conversion regions 32 (photoelectric conversion regions 32R and 32B) arranged below the photoelectric conversion unit 20 and the color filters 55R and 55B, respectively. In the photodetector element 4B of this modified example, the area of ​​each photoelectric conversion portion of RGB can be enlarged compared to a photoelectric conversion element having a general Bayer array, making it possible to improve the S / N ratio.

[0206] 24 is a schematic diagram illustrating a cross-sectional configuration of a photodetector 5 according to a third modification of the present disclosure. The photodetector 5 of this modification has two photoelectric conversion units 20, 80 and one photoelectric conversion region 32 stacked in the vertical direction.

[0207] The photoelectric conversion units 20 and 80 and the photoelectric conversion region 32 selectively detect light in different wavelength ranges and perform photoelectric conversion. For example, the photoelectric conversion unit 20 acquires a green (G) color signal. For example, the photoelectric conversion unit 80 acquires a blue (B) color signal. For example, the photoelectric conversion region 32 acquires a red (R) color signal. This makes it possible for the photodetector element 5 to acquire multiple types of color signals in one pixel without using color filters.

[0208] The photoelectric conversion unit 80 is stacked, for example, above the photoelectric conversion unit 20, and has the same configuration as the photoelectric conversion unit 20. Specifically, the photoelectric conversion unit 80 has a lower electrode 81, an insulating layer 82, an oxide semiconductor layer 83, a photoelectric conversion layer 84, an electron blocking layer 85 consisting of multiple layers, a work function adjustment layer 86, and an upper electrode 87 stacked in this order. Like the photoelectric conversion unit 20, the lower electrode 81 is composed of multiple electrodes (e.g., a readout electrode 81A and a storage electrode 81B) and is electrically isolated by the insulating layer 82. An interlayer insulating layer 89 is provided between the photoelectric conversion unit 80 and the photoelectric conversion unit 20.

[0209] A through electrode 88 is connected to the readout electrode 91A, which penetrates the interlayer insulating layer 89 and the photoelectric conversion unit 20 and is electrically connected to the readout electrode 21A of the photoelectric conversion unit 20. Furthermore, the readout electrode 81A is electrically connected to a floating diffusion FD provided in the semiconductor substrate 30 via the through electrodes 34 and 88, and can temporarily store carriers generated in the photoelectric conversion layer 84. Furthermore, the readout electrode 81A is electrically connected to an amplifier transistor AMP and the like provided in the semiconductor substrate 30 via the through electrodes 34 and 88.

[0210] (4-4. Modifications 4 to 7) FIG. 25 is a schematic diagram illustrating an example of a cross-sectional configuration of a photodetector element (photodetector element 6) according to Modification 4 of the present disclosure. FIG. 26A is a schematic diagram illustrating another example of a cross-sectional configuration of a photodetector element (photodetector element 7A) according to Modification 5 of the present disclosure. FIG. 26B is a schematic diagram illustrating an example of a planar configuration of the photodetector element 7A shown in FIG. 26A. FIG. 27A is a schematic diagram illustrating another example of a cross-sectional configuration of a photodetector element (photodetector element 7B) according to Modification 6 of the present disclosure. FIG. 27B is a schematic diagram illustrating an example of a planar configuration of the photodetector element 7B shown in FIG. 27A. FIG. 28 is a schematic diagram illustrating another example of a cross-sectional configuration of a photodetector element (photodetector element 8) according to Modification 7 of the present disclosure. Like the photodetector element 1 of the first embodiment described above, the photodetector elements 6 to 8 are used as imaging elements such as CMOS image sensors used in electronic devices such as digital still cameras and video cameras. The photodetecting elements 6 to 8 of this modified example differ from those of the above embodiment and the like in that the lower electrode 21 is made up of one electrode for each unit pixel P.

[0211] Similar to the photodetector element 1, the photodetector element 6 has one photoelectric conversion unit 20 and two photoelectric conversion regions 32B, 32R stacked in the vertical direction for each unit pixel P. The photoelectric conversion unit 20 is provided on the back surface (first surface 30A) side of the semiconductor substrate 30. The photoelectric conversion regions 32B, 32R are embedded in the semiconductor substrate 30 and stacked in the thickness direction of the semiconductor substrate 30.

[0212] The photodetection element 8 of this modified example has the same configuration as the photodetection element 1, except that, as described above, the lower electrodes 21, 81 of the photoelectric conversion units 20, 80 consist of a single electrode, and no insulating layers 22, 82 are provided between the lower electrodes 21, 81 and the oxide semiconductor layers 23, 83.

[0213] In this way, the configuration of the photoelectric conversion units 20 and 80 is not limited to the photodetector element 1 of the first embodiment described above, and the same effects as those of the first embodiment can be obtained even if the configuration of the photoelectric conversion units 60, 70A, and 70B of the second or third embodiment described above is used.

[0214] 5. Application Examples Application Example 1 FIG. 29 shows an example of the overall configuration of a photodetector (photodetector 100) including the photodetector element (for example, the photodetector element 1) shown in FIG. 1 and the like.

[0215] The photodetector 100 is, for example, a CMOS image sensor that captures incident light (image light) from a subject via an optical lens system (not shown), converts the amount of incident light imaged on an imaging surface into an electrical signal for each pixel, and outputs the signal as a pixel signal. The photodetector 100 has a pixel section 100A as an imaging area on a semiconductor substrate 30, and also has, in a peripheral region of the pixel section 100A, for example, a vertical drive circuit 111, a column signal processing circuit 112, a horizontal drive circuit 113, an output circuit 114, a control circuit 115, and input / output terminals 116.

[0216] The pixel section 100A has, for example, a plurality of unit pixels P arranged two-dimensionally in a matrix. For example, pixel drive lines Lread (specifically, row selection lines and reset control lines) are wired to each unit pixel P for each pixel row, and vertical signal lines Lsig are wired to each pixel column. The pixel drive lines Lread transmit drive signals for reading signals from the pixels. One end of each pixel drive line Lread is connected to an output terminal of the vertical drive circuit 111 corresponding to each row.

[0217] The vertical drive circuit 111 is a pixel drive unit that includes a shift register, an address decoder, etc., and drives each unit pixel P of the pixel unit 100A, for example, row by row. Signals output from each unit pixel P of a pixel row selected and scanned by the vertical drive circuit 111 are supplied to a column signal processing circuit 112 through each vertical signal line Lsig. The column signal processing circuit 112 is configured with an amplifier, a horizontal selection switch, etc., provided for each vertical signal line Lsig.

[0218] The horizontal drive circuit 113 is configured with a shift register, an address decoder, etc., and scans and sequentially drives each horizontal selection switch of the column signal processing circuit 112. By selective scanning by this horizontal drive circuit 113, signals of each pixel transmitted through each vertical signal line Lsig are output in sequence to horizontal signal lines 121 and transmitted to the outside of the semiconductor substrate 30 through the horizontal signal lines 121.

[0219] The output circuit 114 processes and outputs signals sequentially supplied from each of the column signal processing circuits 112 via the horizontal signal line 121. The output circuit 114 may perform only buffering, or may perform black level adjustment, column variation correction, various digital signal processing, and the like, for example.

[0220] The circuit portion consisting of the vertical drive circuit 111, the column signal processing circuit 112, the horizontal drive circuit 113, the horizontal signal line 121, and the output circuit 114 may be formed directly on the semiconductor substrate 30, or may be disposed on an external control IC. Furthermore, these circuit portions may be formed on another substrate connected by a cable or the like.

[0221] The control circuit 115 receives a clock and data instructing an operation mode from outside the semiconductor substrate 30, and outputs data such as internal information of the photodetector 100. The control circuit 115 further has a timing generator that generates various timing signals, and controls the driving of peripheral circuits such as the vertical drive circuit 111, the column signal processing circuit 112, and the horizontal drive circuit 113 based on the various timing signals generated by the timing generator.

[0222] The input / output terminal 116 is used to exchange signals with the outside.

[0223] (Application Example 2) Furthermore, the photodetector 100 as described above can be applied to various electronic devices, such as imaging systems such as digital still cameras and digital video cameras, mobile phones with imaging functions, or other devices with imaging functions.

[0224] FIG. 30 is a block diagram showing an example of the configuration of electronic device 1000.

[0225] As shown in Figure 30, electronic device 1000 includes an optical system 1001, a photodetector 100, and a DSP (Digital Signal Processor) 1002, and is configured by connecting DSP 1002, memory 1003, display device 1004, recording device 1005, operation system 1006, and power supply system 1007 via a bus 1008, and is capable of capturing still images and moving images.

[0226] The optical system 1001 is configured to have one or more lenses, and receives incident light (image light) from an object and forms an image on the imaging surface of the photodetector 100 .

[0227] The photodetector 100 converts the amount of incident light that is imaged on the imaging surface by the optical system 1001 into an electrical signal for each pixel, and supplies the signal to the DSP 1002 as a pixel signal.

[0228] The DSP 1002 performs various signal processing on the signal from the photodetector 100 to acquire an image, and temporarily stores the image data in a memory 1003. The image data stored in the memory 1003 is recorded in a recording device 1005 or supplied to a display device 1004 to display the image. An operation system 1006 accepts various operations by a user and supplies operation signals to each block of the electronic device 1000, and a power supply system 1007 supplies power necessary to drive each block of the electronic device 1000.

[0229] 31A is a schematic diagram illustrating an example of the overall configuration of a light detection system 2000 including the light detection device 100. FIG. 31B is a diagram illustrating an example of the circuit configuration of the light detection system 2000. The light detection system 2000 includes a light emitting device 2001 serving as a light source unit that emits infrared light L2, and a light detection device 2002 serving as a light receiving unit having a photoelectric conversion element. The light detection device 100 described above can be used as the light detection device 2002. The light detection system 2000 may further include a system control unit 2003, a light source driving unit 2004, a sensor control unit 2005, a light source side optical system 2006, and a camera side optical system 2007.

[0230] The photodetector 2002 can detect light L1 and light L2. Light L1 is external ambient light reflected by the object (measurement target) 2100 ( FIG. 31A ). Light L2 is light emitted by the light-emitting device 2001 and then reflected by the object 2100. Light L1 is, for example, visible light, and light L2 is, for example, infrared light. Light L1 can be detected by a photoelectric conversion unit in the photodetector 2002, and light L2 can be detected by a photoelectric conversion region in the photodetector 2002. Image information of the object 2100 can be obtained from light L1, and distance information between the object 2100 and the photodetector system 2000 can be obtained from light L2. The photodetector system 2000 can be installed in, for example, an electronic device such as a smartphone or a mobile object such as a car. The light-emitting device 2001 can be configured, for example, by a semiconductor laser, a surface-emitting semiconductor laser, or a vertical-cavity surface-emitting laser (VCSEL). The method of detecting the light L2 emitted from the light-emitting device 2001 by the photodetector 2002 can be, for example, an iTOF method, but is not limited to this. In the iTOF method, the photoelectric conversion unit can measure the distance to the subject 2100, for example, by using the time-of-flight (TOF) of light. The method of detecting the light L2 emitted from the light-emitting device 2001 by the photodetector 2002 can also be, for example, a structured light method or a stereo vision method. For example, in the structured light method, a predetermined pattern of light is projected onto the subject 2100, and the distance between the photodetector system 2000 and the subject 2100 can be measured by analyzing the distortion of the pattern. In addition, in the stereo vision method, for example, two or more cameras are used to acquire two or more images of the subject 2100 viewed from two or more different viewpoints, thereby measuring the distance between the photodetector system 2000 and the subject. The light emitting device 2001 and the light detecting device 2002 can be controlled synchronously by a system control unit 2003 .

[0231] 6. Application Example Application Example to an 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.

[0232] FIG. 32 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.

[0233] 32 shows an operator (doctor) 11131 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.

[0234] 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 example shown, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may also be configured as a so-called flexible scope having a flexible lens barrel.

[0235] 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 object to be observed inside 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.

[0236] An optical system and an image sensor are provided inside the camera head 11102, and light reflected from the object of observation (observation light) is collected onto 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 the observed image. The image signal is sent to a camera control unit (CCU) 11201 as RAW data.

[0237] The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls 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 image processing on the image signal, such as development processing (demosaic processing), to display an image based on the image signal.

[0238] 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.

[0239] The light source device 11203 is composed of a light source such as an LED (light emitting diode), and supplies irradiation light to the endoscope 11100 when photographing the surgical site, etc.

[0240] 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 irradiation light, magnification, focal length, etc.) of the endoscope 11100.

[0241] 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 inflates the body cavity of the patient 11132 through the insufflation tube 11111 in order to ensure a clear field of view for the endoscope 11100 and a working space for the surgeon. The recorder 11207 is a device capable of recording various types of information related to the surgery. The printer 11208 is a device capable of printing various types of information related to the surgery in various formats such as text, images, or graphs.

[0242] The light source device 11203, which supplies illumination light to the endoscope 11100 when photographing the surgical site, can be configured from a white light source, such as an LED, a laser light source, or a combination of these. When the white light source is configured from a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, allowing the light source device 11203 to adjust the white balance of the captured image. In this case, it is also possible to time-share images corresponding to each RGB by irradiating the object of observation with laser light from each RGB laser light source and controlling the drive of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, color images can be obtained without providing a color filter to the image sensor.

[0243] Furthermore, the light source device 11203 may be controlled to change the intensity of light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 11102 in synchronization with the timing of the change in light intensity to acquire images in a time-division manner and combining the images, it is possible to generate an image with a high dynamic range that is free from so-called blocked-up shadows and blown-out highlights.

[0244] The light source device 11203 may also be configured to supply light in a predetermined wavelength range compatible with special light observation. Special light observation, for example, utilizes the wavelength dependence of light absorption in body tissues to irradiate light with a narrower band than the light irradiated during normal observation (i.e., white light), thereby capturing high-contrast images of specific tissues, such as blood vessels on the surface of mucous membranes, known as narrow-band imaging. Alternatively, special light observation may involve fluorescence observation, in which images are obtained using fluorescence generated by irradiating excitation light. Fluorescence observation can involve irradiating excitation light onto body tissues and observing the fluorescence from the tissues (autofluorescence observation), or by locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the 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 compatible with such special light observation.

[0245] FIG. 33 is a block diagram showing an example of the functional configuration of the camera head 11102 and the CCU 11201 shown in FIG.

[0246] 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 via a transmission cable 11400 so that they can communicate with each other.

[0247] 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 composed of a combination of multiple lenses including a zoom lens and a focus lens.

[0248] The imaging unit 11402 may include one imaging element (a so-called single-chip type) or multiple imaging elements (a so-called multi-chip type). When the imaging unit 11402 is configured as a multi-chip 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 these 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. The 3D display allows the surgeon 11131 to more accurately grasp the depth of the biological tissue at the surgical site. Note that when the imaging unit 11402 is configured as a multi-chip type, multiple lens units 11401 may be provided corresponding to each imaging element.

[0249] 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 after the objective lens.

[0250] 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 adjusted appropriately.

[0251] The communication unit 11404 is configured by a communication device for transmitting and receiving various types of 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.

[0252] 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 imaging, and / or information specifying the magnification and focus of the captured image.

[0253] The image capturing conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the 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.

[0254] 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 .

[0255] The communication unit 11411 is configured by 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.

[0256] 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.

[0257] The image processing unit 11412 performs various image processing operations on the image signal, which is RAW data transmitted from the camera head 11102 .

[0258] The control unit 11413 performs various controls related to the imaging of the surgical site, etc. by the endoscope 11100 and the 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.

[0259] Furthermore, the control unit 11413 displays the captured image showing the surgical site, etc., on the display device 11202 based on the image signal subjected to image processing 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 technologies. For example, the control unit 11413 can recognize surgical tools such as forceps, specific biological parts, bleeding, mist generated when using the energy treatment tool 11112, etc., by detecting the shape and color of the edges of objects included in the captured image. When displaying the captured image on the display device 11202, the control unit 11413 may use the recognition results to superimpose various surgical support information on the image of the surgical site. By superimposing the surgical support information and presenting it to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

[0260] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for electrical signal communication, an optical fiber for optical communication, or a composite cable of these.

[0261] 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.

[0262] The above describes an example of an endoscopic surgery system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the imaging unit 11402 among the components described above. By applying the technology according to the present disclosure to the imaging unit 11402, detection accuracy is improved.

[0263] 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.

[0264] (Application Example to Mobile Object) 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 mobile object, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, a robot, construction machinery, or agricultural machinery (tractor).

[0265] FIG. 34 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0266] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 34, 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 shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053.

[0267] 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.

[0268] The body system control unit 12020 controls the operation of various devices equipped in 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 headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0269] 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 images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0270] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding 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.

[0271] 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 off.

[0272] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands 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 distance between vehicles, maintaining vehicle speed, vehicle collision warning, vehicle lane departure warning, etc.

[0273] 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 driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0274] 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 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 information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0275] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying information to vehicle occupants or the outside of the vehicle. In the example of Fig. 34, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0276] FIG. 35 is a diagram showing an example of the installation position of the imaging unit 12031.

[0277] In FIG. 35, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0278] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided on the top of the windshield inside the vehicle cabin is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0279] 35 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, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0280] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0281] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which runs autonomously without relying on driver operation.

[0282] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding 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. The microcomputer 12051 then determines a collision risk that indicates 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.

[0283] At least one of the image capturing 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 a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0284] The foregoing has described an example of a mobile object control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the image capture unit 12031 of the above-described configuration. Specifically, the photodetector element (e.g., photodetector element 1) according to the above-described embodiment and its modified examples 1 to 6 can be applied to the image capture unit 12031. By applying the technology according to the present disclosure to the image capture unit 12031, it is possible to obtain a high-resolution captured image with little noise, thereby enabling high-precision control using the captured image in the mobile object control system.

[0285] 7. Examples Next, examples of the present disclosure will be described.

[0286] (Experiment 1) In Experiment 1, the photoresponse was evaluated when an electron blocking layer, a work function adjusting layer, and an electron injection layer were formed on a photoelectric conversion layer.

[0287] (Experimental Example 1) First, a 100 nm thick ITO film was formed on a silicon substrate using a sputtering device. This was then processed by photolithography and etching to form a lower electrode. Next, an insulating film was formed on the silicon substrate and the lower electrode, and a 1 mm square opening was formed by lithography and etching to expose the lower electrode. Next, the silicon substrate was cleaned by UV / ozone treatment, and then the silicon substrate was transferred to a vacuum deposition device, and the deposition chamber was filled with 1 × 10 －５ While rotating the substrate holder under reduced pressure of 0.1 Pa or less, a photoelectric conversion layer was formed on the lower electrode. Further, electron blocking layer 1 was formed using compound 1, electron blocking layer 2 was formed using compound 2, and a work function adjustment layer was formed using HATCN ([dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile]). Next, a nitride film was formed on the surface of the work function adjustment layer under a nitrogen atmosphere, which served as an electron injection layer. Finally, the silicon substrate was transferred to a sputtering apparatus, and a 50 nm thick ITO film was formed on the work function adjustment layer, which served as an upper electrode. The silicon substrate was then annealed at 150°C for 210 minutes under a nitrogen atmosphere to produce an evaluation element.

[0288] Experimental Example 2 An evaluation element was fabricated in the same manner as in Experimental Example 1, except that the electron injection layer formed in Experimental Example 1 was omitted.

[0289] Experimental Example 3 An evaluation device was fabricated in the same manner as in Experimental Example 1, except that Compound 3 was used to form the electron injection layer.

[0290] Experimental Example 4 An evaluation element was fabricated in the same manner as in Experimental Example 3, except that the electron blocking layer 2 was formed using Compound 4.

[0291] Experimental Example 5 An evaluation element was fabricated in the same manner as in Experimental Example 3, except that electron blocking layer 1 was formed using compound 5 and electron blocking layer 2 was formed using compound 1.

[0292] Experimental Example 6 An evaluation element was fabricated in the same manner as in Experimental Example 5, except that the electron blocking layer 1 was formed using Compound 5.

[0293] Experimental Example 7 An evaluation device was fabricated in the same manner as in Experimental Example 3, except that Compound 7 was used to form the electron injection layer.

[0294] Experimental Example 8 An evaluation element was fabricated in the same manner as in Experimental Example 1, except that the electron blocking layer 2 and the electron injection layer were omitted.

[0295] Experimental Example 9 An evaluation device was fabricated in the same manner as in Experimental Example 1, except that the electron blocking layer 2 was omitted and the electron injection layer was formed using Compound 7.

[0296] Experimental Example 10 An evaluation element was fabricated in the same manner as in Experimental Example 3, except that the electron blocking layer 2 was formed using Compound 8.

[0297] (Evaluation of Photoresponse) The wavelength of light irradiated onto the photoelectric conversion element from a green LED light source through a bandpass filter was 560 nm, and the light intensity was 162 μW / cm ２ The voltage applied to the LED driver was controlled by a function generator, and pulsed light with a pulse width of 100 ms was irradiated from the upper electrode 16 side. The bias voltage applied between the electrodes of the evaluation element was set to +2.6 V with respect to the upper electrode 16, and the pulsed light was irradiated, and the current decay waveform was observed using an oscilloscope. The amount of coulombs during the current decay process 110 ms after the light pulse irradiation was stopped was measured, and this was used as an index of the amount of image lag. A lower amount of image lag indicates a faster photoresponse.

[0298]

[0299] Table 1 summarizes the materials of electron blocking layers 1 and 2 and the ionization energy IP (eV) of each material, the energy difference (ΔeV) between electron blocking layers 1 and 2, the materials of the work function adjustment layer and their electron affinities EA (eV), the materials of the electron injection layer and their electrostatic potentials ESP, and the photoresponsiveness in Experimental Examples 1 to 10. In Table 1, the characteristic value of Experimental Example 9 is set as the reference value (1.0) for photoresponsiveness, and this was given a rating of C. For Experimental Examples 1 to 8 and 10, relative values ​​to the reference value (1.0) were calculated, and values ​​less than 0.7 were given a rating of A, values ​​at least 0.7 but less than 1.0 were given a rating of B, and values ​​greater than 1.0 were given a rating of D.

[0300] Experimental Examples 1 to 7, which had a cascade structure (two layers in this case) and an electron blocking layer with an energy difference (ΔeV) of 0.03 eV or more, were confirmed to have improved photoresponse compared to Experimental Example 9, which had a single electron blocking layer. ｍｉｎ Experimental Examples 3 to 7, which had an electron injection layer satisfying ESP≦−0.09, showed a greater improvement in photoresponse than Experimental Example 1, which had an electron blocking layer outside the above range, and Experimental Example 2, which had no electron blocking layer. Furthermore, the results of Experimental Examples 8 and 9 show that even without a cascade structure for the electron blocking layer, ESP≦−0.11. ｍｉｎ It was found that the photoresponse can be improved by providing an electron injection layer that satisfies the condition of ≦−0.09.

[0301] (Experiment 2) In Experiment 2, the photoresponse was evaluated when one or both of a work function adjustment layer and a protective layer were formed as intermediate layers between the photoelectric conversion layer and the upper electrode.

[0302] (Experimental Example 11) First, a 100 nm thick ITO film was formed on a silicon substrate using a sputtering device. This was then processed by photolithography and etching to form a lower electrode. Next, an insulating film was formed on the silicon substrate and the lower electrode, and a 1 mm square opening was formed by lithography and etching to expose the lower electrode. Next, the silicon substrate was cleaned by UV / ozone treatment, and then the silicon substrate was transferred to a vacuum deposition device, and the deposition chamber was filled with 1 × 10 －５While rotating the substrate holder under reduced pressure of 0.1 Pa or less, a photoelectric conversion layer was formed on the lower electrode, and a work function adjustment layer was further formed using Compound 9. Finally, the silicon substrate was transferred to a sputtering apparatus, and a 50 nm thick ITO film was formed on the work function adjustment layer to serve as the upper electrode. Thereafter, the silicon substrate was annealed at 150°C for 210 minutes in a nitrogen atmosphere to obtain an evaluation element.

[0303] Experimental Example 12 An evaluation element was fabricated in the same manner as in Experimental Example 11, except that Compound 10 was used to form the work function adjustment layer.

[0304] Experimental Example 13 An evaluation element was fabricated in the same manner as in Experimental Example 11, except that a work function adjustment layer was formed using HATCN and a protective layer was formed using Compound 3.

[0305] Experimental Example 14 An evaluation element was fabricated in the same manner as in Experimental Example 11, except that the work function adjustment layer was formed using HATCN.

[0306] Experimental Example 15 An evaluation element was fabricated in the same manner as in Experimental Example 11, except that Compound 3 was used to form the work function adjustment layer.

[0307] Experimental Example 16 An evaluation element was fabricated in the same manner as in Experimental Example 11, except that Compound 11 was used to form the work function adjustment layer.

[0308] Experimental Example 17 An evaluation element was fabricated in the same manner as in Experimental Example 11, except that Compound 12 was used to form the work function adjustment layer.

[0309] (Evaluation of Photoresponse) The wavelength of light irradiated onto the photoelectric conversion element from a green LED light source through a bandpass filter was 560 nm, and the light intensity was 162 μW / cm ２The voltage applied to the LED driver was controlled by a function generator, and pulsed light with a pulse width of 100 ms was irradiated from the upper electrode 16 side. The bias voltage applied between the electrodes of the evaluation element was set to +2.6 V with respect to the upper electrode 16, and the pulsed light was irradiated, and the current decay waveform was observed using an oscilloscope. The amount of coulombs during the current decay process 110 ms after the light pulse irradiation was stopped was measured, and this was used as an index of the amount of image lag. A lower amount of image lag indicates a faster photoresponse.

[0310]

[0311] Table 2 shows the materials of the work function adjusting layer and the protective layer in Experimental Examples 11 to 17 and the electron affinity EA of each material. ｗ (eV), the minimum binding energy Eb of each layer １ (eV), the change in electron affinity ΔEA when all bonds are dissociated and replaced with hydrogen １ The table below summarizes the optical response (eV) and the evaluation of the optical response. In Table 2, the characteristic value of Experimental Example 14 was set as the reference value (1.0) for optical response, and this was evaluated as B. If the optical response was better than this reference value (1.0), it was evaluated as A, and if the optical response was equal to or worse than the reference value (1.0), it was evaluated as B.

[0312] Minimum binding energy is -5.33 eV < Eb １ <8.67 eV and when all the bonds in each layer are dissociated and replaced with hydrogen, the electron affinity change ΔEA ｎ In Experimental Examples 11 to 13, where the ΔEA after bond dissociation was less than 0.3, improvement in the photoresponsiveness was confirmed. １ In Experimental Examples 16 and 17, where the (eV) was outside the above range, deterioration in the light response was confirmed.

[0313] Although the first to third embodiments, variations 1 to 7, application examples, and examples have been described above, the present disclosure is not limited to the above embodiments and various modifications are possible. For example, in the first embodiment, the photodetector element is configured by stacking a photoelectric conversion unit 20 that detects green light and photoelectric conversion regions 32B and 32R that detect blue light and red light, respectively. However, the present disclosure is not limited to such a structure. For example, the photoelectric conversion unit may be configured to detect red light or blue light, or the photoelectric conversion region may be configured to detect green light.

[0314] Furthermore, the number and ratio of these photoelectric conversion units and photoelectric conversion regions are not limited, and two or more photoelectric conversion units may be provided, or color signals of multiple colors may be obtained using only the photoelectric conversion units.

[0315] Furthermore, in the above-described embodiments, two electrodes, namely, the readout electrode 21A and the storage electrode 21B, have been shown as the multiple electrodes constituting the lower electrode 21. However, as a specific example of the "fourth electrode" according to one embodiment of the present disclosure, for example, three or more electrodes, such as a transfer electrode 21D and an exhaust electrode 21E, may be provided, as shown in FIG. 36 .

[0316] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0317] The present technology can also be configured as follows. According to the present technology configured as follows, it is possible to improve photoresponsiveness. [1] A photodetector comprising: a first electrode; a second electrode arranged opposite to the first electrode; a photoelectric conversion layer provided between the first electrode and the second electrode; a work function adjustment layer provided between the photoelectric conversion layer and the second electrode; and a plurality of electron blocking layers provided between the photoelectric conversion layer and the work function adjustment layer, the plurality of electron blocking layers having shallower ionization energies in order from the photoelectric conversion layer side toward the work function adjustment layer. [2] The plurality of electron blocking layers include a first electron blocking layer adjacent to the photoelectric conversion layer, an nth electron blocking layer adjacent to the work function adjustment layer, and an (n-1)th electron blocking layer adjacent to the nth electron blocking layer on the opposite side to the work function adjustment layer, and the ionization energy of the photoelectric conversion layer is defined as IP1, the ionization energy of the first electron blocking layer is defined as IP ２ , the ionization energy of the (n-1)th electron blocking layer is IP ｎ－１ , the ionization energy of the nth electron blocking layer is IP ｎ and the electron affinity of the work function adjusting layer is EA ｗ The photodetector according to [1], wherein the following formula (1) is satisfied when EA ｗ <IP ｎ ≦IP ｎ－１ +0.03 (1) [3] An electron injection layer is further provided between the work function adjustment layer and the second electrode, and the electron injection layer has an electrostatic potential ESP that satisfies the following formula (2): ｍｉｎ The photodetector according to the above [1] or [2], wherein (Equation 2) -0.11≦ESP ｍｉｎ≦−0.09 (2) [4] The photodetector according to any one of [1] to [3], wherein the plurality of electron blocking layers contain an organic material. [5] The photodetector according to any one of [1] to [4], wherein the electron injection layer contains an organic material. [6] The photodetector according to any one of [1] to [5], further comprising: a third electrode arranged in parallel with the first electrode; an oxide semiconductor layer provided between the first electrode and the third electrode and the photoelectric conversion layer; and an insulating layer provided between the first electrode and the third electrode and the oxide semiconductor layer, the insulating layer having an opening above the first electrode, wherein the first electrode and the oxide semiconductor layer are electrically connected via the opening. [7] The photodetector according to [6], wherein a voltage is applied to the first electrode and the third electrode individually. [8] A photoelectric conversion layer provided between the first electrode and the second electrode; an electron blocking layer provided between the photoelectric conversion layer and the second electrode; and an electrostatic potential ESP provided between the electron blocking layer and the second electrode, which satisfies the following formula (3): ｍｉｎ and a photodetector comprising: an electron injection layer having (Equation 3) -0.11≦ESP ｍｉｎ ≦−0.09 (3) [9] The photodetector according to [8], further comprising a work function adjusting layer between the photoelectric conversion layer and the electron injection layer.

[10] A first electrode, a second electrode disposed opposite to the first electrode, a photoelectric conversion layer provided between the first electrode and the second electrode, and a minimum binding energy Eb １ or the first intermediate layer having the lowest binding energy Eb １ , the nth lowest binding energy Eb ｎ (n≧2) and the n+1 lowest n+1 binding energy Eb ｎ＋１ (n≧2), and the nth bond energy Eb ｎ, the n+1 bond energy Eb ｎ＋１ and the electron affinity change ΔEA when all bonds from the lowest bond energy to the nth bond energy are dissociated and replaced with hydrogen. ｎ and a second intermediate layer satisfying the following formulas (5), (6), and (7): −5.33 eV<Eb (Formula 4). １ <8.67eV (4) (Math. 5) Eb ｎ ≦5.33eV (5) 5.33eV<Eb ｎ＋１ <8.67eV...(6) ΔEA ｎ <0.3 (7)

[11] The photodetector according to

[10] , further comprising a work function adjustment layer between the photoelectric conversion layer and the second electrode, the work function adjustment layer having an electron affinity greater than the work function of the first electrode, and the first intermediate layer or the second intermediate layer being the work function adjustment layer.

[12] The photodetector according to

[10] or

[11] , further comprising a protective layer between the photoelectric conversion layer and the second electrode, the first intermediate layer or the second intermediate layer being the protective layer.

[0318] This application claims priority based on Japanese Patent Application No. 2023-208085, filed on December 8, 2023, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0319] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur depending on design requirements and other factors, and are intended to be within the scope of the appended claims and their equivalents.

Claims

1. A photodetector comprising: a first electrode; a second electrode disposed opposite the first electrode; a photoelectric conversion layer provided between the first electrode and the second electrode; a work function adjustment layer provided between the photoelectric conversion layer and the second electrode; and a plurality of electron blocking layers provided between the photoelectric conversion layer and the work function adjustment layer, the electron blocking layers having shallower ionization energies in a direction from the photoelectric conversion layer side toward the work function adjustment layer.

2. The plurality of electron blocking layers include a first electron blocking layer adjacent to the photoelectric conversion layer, an nth electron blocking layer adjacent to the work function adjustment layer, and an n-1th electron blocking layer adjacent to the nth electron blocking layer on the opposite side to the work function adjustment layer, and the ionization energy of the photoelectric conversion layer is IP1 and the ionization energy of the first electron blocking layer is IP ２ , the ionization energy of the n-1th electron blocking layer is IP ｎ－１ , the ionization energy of the nth electron blocking layer is IP ｎ and the electron affinity of the work function adjusting layer is EA ｗ The photodetector according to claim 1, wherein the following formula (1) is satisfied when EA ｗ <IP ｎ ≦IP ｎ－１ +0.03 ... (1) 3. An electron injection layer is further provided between the work function adjustment layer and the second electrode, and the electron injection layer has an electrostatic potential ESP that satisfies the following formula (2): ｍｉｎ 2. The light detection device according to claim 1, wherein ESP is a function of -0.

11. ｍｉｎ ≦-0.09 (2) 4. The photodetection device of claim 1, wherein said plurality of electron blocking layers comprises an organic material.

5. The photodetector device of claim 1, wherein the electron injection layer comprises an organic material.

6. The photodetector device of claim 1, further comprising: a third electrode arranged in parallel with the first electrode; an oxide semiconductor layer provided between the first electrode and the third electrode and the photoelectric conversion layer; and an insulating layer provided between the first electrode and the third electrode and the oxide semiconductor layer and having an opening above the first electrode, wherein the first electrode and the oxide semiconductor layer are electrically connected via the opening.

7. The light detection device according to claim 6, wherein a voltage is applied to the first electrode and the third electrode individually.

8. A semiconductor device comprising: a first electrode; a second electrode disposed opposite to the first electrode; a photoelectric conversion layer provided between the first electrode and the second electrode; an electron blocking layer provided between the photoelectric conversion layer and the second electrode; and an electrostatic potential ESP provided between the electron blocking layer and the second electrode, the electrostatic potential ESP satisfying the following formula (3): ｍｉｎ and a photodetector comprising: an electron injection layer having the formula (3) -0.11≦ESP ｍｉｎ ≦−0.09 (3) 9. The photodetector according to claim 8, further comprising a work function adjustment layer between said photoelectric conversion layer and said electron injection layer.

10. A semiconductor device comprising: a first electrode; a second electrode disposed opposite to the first electrode; a photoelectric conversion layer provided between the first electrode and the second electrode; and a minimum binding energy Eb １ or the first intermediate layer having a minimum binding energy Eb １ , the nth lowest binding energy Eb ｎ (n≧2) and the n+1 lowest n+1-th binding energy Eb ｎ＋１ (n≧2), and the nth bond energy Eb ｎ , the n+1 bond energy Eb ｎ＋１ and the change in electron affinity ΔEA when all bonds from the lowest bond energy to the nth bond energy are dissociated and replaced with hydrogen ｎ and a second intermediate layer satisfying the following formulas (5), (6), and (7): −5.33 eV<Eb １ <8.67eV...(4) (Math. 5) Eb ｎ ≦5.33eV (5) 5.33eV<Eb ｎ＋１ <8.67eV...(6) ΔEA ｎ <0.3 ... (7) 11. The photodetector device described in claim 10, further comprising a work function adjustment layer between the photoelectric conversion layer and the second electrode, the work function adjustment layer having an electron affinity greater than the work function of the first electrode, and the first intermediate layer or the second intermediate layer being the work function adjustment layer.

12. The photodetector device described in claim 10, further comprising a protective layer between the photoelectric conversion layer and the second electrode, the protective layer having an electron affinity greater than the work function of the second electrode, and the first intermediate layer or the second intermediate layer being the protective layer.

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