阅读说明：本技术 光电转换元件和摄像装置 (Photoelectric conversion element and imaging device ) 是由 塩见治典 森胁俊贵 于 2019-01-18 设计创作，主要内容包括：根据本发明实施方式的光电转换元件包括：第一电极,其包括相互独立的多个电极；第二电极,其与第一电极相对；光电转换层,其包括量子点并且被布置在第一电极与第二电极之间；以及半导体层,其包括氧化物半导体材料并且被布置在第一电极与光电转换层之间。光电转换层的传导带的能级等于或低于半导体层的传导带的能级。(The photoelectric conversion element according to the embodiment of the present invention includes: a first electrode including a plurality of electrodes independent of each other; a second electrode opposite to the first electrode; a photoelectric conversion layer including quantum dots and disposed between the first electrode and the second electrode; and a semiconductor layer including an oxide semiconductor material and disposed between the first electrode and the photoelectric conversion layer. An energy level of a conduction band of the photoelectric conversion layer is equal to or lower than an energy level of a conduction band of the semiconductor layer.)

1. A photoelectric conversion element, comprising:

a first electrode including a plurality of electrodes independent of each other;

a second electrode disposed opposite to the first electrode;

a photoelectric conversion layer including semiconductor nanoparticles, and disposed between the first electrode and the second electrode; and

a semiconductor layer including an oxide semiconductor material and disposed between the first electrode and the photoelectric conversion layer, wherein

An energy level of a conduction band of the photoelectric conversion layer is equal to or higher than an energy level of a conduction band of the semiconductor layer.

2. The photoelectric conversion element according to claim 1, wherein the energy level of the conduction band of the photoelectric conversion layer and the energy level of the conduction band of the semiconductor layer have a difference of 0eV or more and 0.2eV or less.

3. The photoelectric conversion element according to claim 1, wherein the energy level of the conduction band of the photoelectric conversion layer is equal to the energy level of the conduction band of the semiconductor layer.

4. The photoelectric conversion element according to claim 1, wherein the semiconductor nanoparticles have a band gap of 0.6eV or more and 1.3eV or less.

5. The photoelectric conversion element according to claim 1, wherein

The semiconductor nanoparticles include a core and a ligand bound to a surface of the core, and

the core is composed of PbS, PbSe, PbTe, CuInSe₂、ZnCuInSe、CuInS₂、ZnCuInS、CuInTe₂、ZnCuInTe、AgInSe₂、ZnAgInSe、AgInTe₂、ZnAgInTe、ZnCuSnSSe、HgTe、InAs、InSb、Ag₂S、Ag₂Se、Ag₂Te、CH₃NH₃SnI₃、CH₃NH₃SnPbI₃、CsSnI₃And CsSnPbI₃The semiconductor particles of any one of.

6. The photoelectric conversion element according to claim 1, wherein

The semiconductor nanoparticles include a core and a ligand bound to a surface of the core, and

the ligand includes any one of a chlorine atom, a bromine atom, an iodine atom and a sulfur atom.

7. The photoelectric conversion element according to claim 5, wherein

The semiconductor nanoparticle further includes a shell disposed about the core, and

the shell is composed of PbO, PbO₂、Pb₃O₄At least one of ZnS, ZnSe, ZnTe, GaS and GaSe.

8. The photoelectric conversion element according to claim 1, wherein the semiconductor layer is configured to include IGZO, ZTO, Zn₂SnO₄、InGaZnSnO、GTO、Ga₂O₃:SnO₂And an IGO.

9. The photoelectric conversion element according to claim 1, wherein the first electrode comprises an electrode material having a work function smaller than that of the second electrode.

10. The photoelectric conversion element according to claim 1, wherein

The first electrode is formed by using any one of titanium (Ti), silver (Ag), aluminum (Al), magnesium (Mg), chromium (Cr), nickel (Ni), tungsten (W), and copper (Cu), and

the second electrode is formed by using Indium Tin Oxide (ITO).

11. The photoelectric conversion element according to claim 1, comprising:

an insulating layer between the first electrode and the semiconductor layer, wherein

The first electrode includes a charge readout electrode electrically connected to the photoelectric conversion layer via an opening provided to the insulating layer, and a charge accumulation electrode arranged to be opposed to the photoelectric conversion layer with the insulating layer interposed therebetween.

12. The photoelectric conversion element according to claim 11, wherein the first electrode comprises a charge transfer electrode between the charge readout electrode and the charge accumulation electrode.

13. The photoelectric conversion element according to claim 1, wherein the plurality of electrodes included in the first electrode are respectively applied with respective voltages.

14. The photoelectric conversion element according to claim 1, further comprising:

a semiconductor substrate of

The first electrode, the semiconductor layer, the photoelectric conversion layer, and the second electrode are provided in this order on a first surface side of the semiconductor substrate.

15. The photoelectric conversion element according to claim 14, wherein the semiconductor substrate comprises a driving circuit, and the plurality of electrodes included in the first electrode are respectively connected to the driving circuit.

16. The photoelectric conversion element according to claim 14, wherein a multilayer wiring layer is formed on a second surface side of the semiconductor substrate which is opposite to the first surface.

17. An image pickup apparatus includes a plurality of pixels provided with one or more photoelectric conversion elements, respectively,

the one or more photoelectric conversion elements respectively include:

a first electrode including a plurality of electrodes independent of each other,

a second electrode disposed opposite to the first electrode,

a photoelectric conversion layer including semiconductor nanoparticles and disposed between the first electrode and the second electrode, an

A semiconductor layer including an oxide semiconductor material and disposed between the first electrode and the photoelectric conversion layer, wherein

An energy level of a conduction band of the photoelectric conversion layer is equal to or higher than an energy level of a conduction band of the semiconductor layer.

Technical Field

The present invention relates to a photoelectric conversion element having a photoelectric conversion layer including semiconductor nanoparticles, for example, and an imaging device including the photoelectric conversion element.

Background

The pixel size of an image pickup Device such as a Charge Coupled Device (CCD) image sensor or a Complementary Metal Oxide Semiconductor (CMOS) image sensor has been decreasing. In general, an image pickup device having a photoelectric conversion portion outside a semiconductor substrate accumulates charges generated by photoelectric conversion in a Floating Diffusion (FD) layer formed inside the semiconductor substrate.

Incidentally, an image pickup apparatus provided with a photoelectric conversion portion inside a semiconductor substrate temporarily accumulates charges generated by photoelectric conversion in the photoelectric conversion portion inside the semiconductor substrate, and then transfers the charges to the FD. This makes it possible to completely deplete the photoelectric conversion portion. In contrast, as described above, the electric charges generated by the photoelectric conversion portion provided outside the semiconductor substrate are directly accumulated in the FD, and thus it is difficult to completely deplete the photoelectric conversion portion. This increases kTC noise and causes more unfavorable random noise, resulting in degradation of image pickup quality.

To solve this problem, for example, patent document 1 discloses an image pickup element provided with an electrode for charge accumulation. An electrode for charge accumulation is arranged on a first electrode side of the first electrode and a second electrode spaced apart from the first electrode, and is opposed to the photoelectric conversion layer with an insulating layer interposed therebetween. The first electrode and the second electrode are arranged to be opposed to each other with the photoelectric conversion layer interposed therebetween. The first electrode is arranged on the opposite side of the light incident side. The image pickup element can accumulate charges generated by photoelectric conversion in the photoelectric conversion layer, and can completely deplete the charge accumulation section at the start of exposure. Therefore, deterioration in image pickup quality can be reduced.

Reference list

Patent document

Patent document 1: japanese unexamined patent application publication No. 2017-157816

Patent document 2: japanese unexamined patent application publication No. 2010-177392

Disclosure of Invention

Incidentally, as a recently developed photoelectric conversion element sensitive to near infrared light, for example, patent document 2 discloses a photoelectric conversion element using quantum dots (semiconductor nanoparticles) of a narrow gap semiconductor for a photoelectric conversion layer. A photoelectric conversion element having a photoelectric conversion layer formed in the photoelectric conversion element by using semiconductor nanoparticles is required to reduce the occurrence of dark current.

It is desirable to provide a photoelectric conversion element and an image pickup apparatus that can reduce the occurrence of dark current.

A photoelectric conversion element according to an embodiment of the present invention includes: a first electrode including a plurality of electrodes independent of each other; a second electrode disposed opposite to the first electrode; a photoelectric conversion layer including quantum dots; and a semiconductor layer including an oxide semiconductor material. The photoelectric conversion layer is disposed between the first electrode and the second electrode. The semiconductor layer is provided between the first electrode and the photoelectric conversion layer. An energy level of a conduction band of the photoelectric conversion layer is equal to or higher than an energy level of a conduction band of the semiconductor layer.

An image pickup apparatus according to an embodiment of the present invention includes a plurality of pixels each provided with one or more photoelectric conversion elements, and includes the photoelectric conversion element according to the above-described embodiment as a photoelectric conversion element.

In the photoelectric conversion element and the image pickup device according to the respective embodiments of the present invention, the energy level of the photoelectric conversion layer is equal to or higher than the energy level of the conduction band of the semiconductor layer. The photoelectric conversion layer is stacked with the semiconductor layer between the first electrode and the second electrode. The photoelectric conversion layer includes semiconductor nanoparticles. The semiconductor layer includes an oxide semiconductor material. This improves the efficiency of transferring the charges generated in the photoelectric conversion layer to the semiconductor layer.

Drawings

Fig. 1 is a schematic cross-sectional view of an image pickup element according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of the photoelectric conversion element shown in fig. 1.

Fig. 3 is an equivalent circuit diagram of the image pickup element shown in fig. 1.

Fig. 4 is a schematic diagram illustrating an arrangement of a lower electrode and a transistor included in a control portion of the image pickup element shown in fig. 1.

Fig. 5 is a characteristic diagram illustrating a relationship between the particle diameter of the semiconductor nanoparticle and the conduction band and the valence band.

Fig. 6 is a characteristic diagram illustrating energy changes of a conduction band and a valence band of the ligand-type semiconductor nanoparticle.

Fig. 7A is a diagram describing the operation principle of the photoelectric conversion element shown in fig. 1.

Fig. 7B is a diagram describing the operation principle of the photoelectric conversion element shown in fig. 1.

Fig. 7C is a diagram describing the operation principle of the photoelectric conversion element shown in fig. 1.

Fig. 8A is a schematic cross-sectional view for describing a manufacturing method of the image pickup element shown in fig. 1.

Fig. 8B is a schematic sectional view illustrating a step subsequent to fig. 8A.

Fig. 8C is a schematic sectional view illustrating a step subsequent to fig. 8B.

Fig. 8D is a schematic sectional view illustrating a step subsequent to fig. 8C.

Fig. 8E is a schematic sectional view illustrating a step subsequent to fig. 8D.

Fig. 9 is a timing chart illustrating an operation example of the photoelectric conversion element shown in fig. 1.

Fig. 10 is a block diagram illustrating a configuration of an image pickup apparatus including the image pickup element shown in fig. 1 as a pixel.

Fig. 11 is a functional block diagram illustrating an example of an electronic apparatus (camera) including the image pickup device shown in fig. 10.

Fig. 12 is a block diagram showing an example of a schematic configuration of the in-vivo information acquisition system.

Fig. 13 is a diagram showing an example of a schematic configuration of an endoscopic surgical system.

Fig. 14 is a block diagram showing an example of a functional configuration of a camera head and a Camera Control Unit (CCU).

Fig. 15 is a block diagram showing an example of a schematic configuration of a vehicle control system.

Fig. 16 is a diagram for assisting in explaining an example of mounting positions of the vehicle exterior information detecting unit and the imaging unit.

Fig. 17A is a graph illustrating the results of EQE in experimental examples 1 to 4.

Fig. 17B is a graph illustrating the results of dark current in experimental examples 1 to 4.

Fig. 18A is a graph illustrating the results of EQE in experimental examples 5 to 7.

Fig. 18B is a graph illustrating the results of dark current in experimental examples 5 to 7.

Detailed Description

Embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description is a specific example of the present invention, but the present invention is not limited to the following modes. Further, the present invention is not limited to the arrangement, dimensions, dimensional ratios, and the like of the respective components illustrated in the respective drawings. Note that the description is given in the following order.

1. Embodiments (in E)_CS≥E_CCQDAs examples of photoelectric conversion elements having conduction band energy levels of the semiconductor layer (S) and the photoelectric conversion layer (CQD)

1-1. Structure of image pickup element

1-2. method for manufacturing image pickup element

1-3. control method of image pickup element

1-4. action and Effect

2. Application example