PHOTOELECTRIC CONVERSION DEVICE AND IMAGING SYSTEM

• US 20160035920A1
• Filed: 07/08/2015
• Published: 02/04/2016
• Est. Priority Date: 07/31/2014
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tashiro, Kazuaki, Kaifu, Noriyuki, Takahashi, Hidekazu
• Granted Patent: US 10,027,915 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 27/14612 involving a transistor
• CPC Class Codes: H01L 27/14665 Imagers using a photoconductor layer
• CPC Class Codes: H01L 27/14694 The active layers comprising only AIIIBV compounds, e.g. GaAs, InP
• CPC Class Codes: H01L 27/14696 The active layers comprising only AIIBVI compounds, e.g. CdS, ZnS, CdTe
• CPC Class Codes: H04N 25/616 involving a correlated sampling function, e.g. correlated double sampling [CDS] or triple sampling
• CPC Class Codes: H04N 25/626 Reduction of noise due to residual charges remaining after image readout, e.g. to remove ghost images or afterimages
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components
• CPC Class Codes: H04N 25/771 comprising storage means other than floating diffusion
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells

Abstract

A photoelectric conversion device according to an exemplary embodiment includes a pixel which includes a photoelectric conversion unit and an amplifier transistor configured to output a signal generated by the photoelectric conversion unit. The photoelectric conversion unit includes a first electrode, a second electrode electrically connected to the amplifier transistor, a photoelectric conversion layer, and an insulating layer disposed between the photoelectric conversion layer and the second electrode. The photoelectric conversion layer includes quantum dots.

Claims

1. A photoelectric conversion device comprising:

a pixel,

the pixel including

a photoelectric conversion unit, and

an amplification unit configured to output a signal generated by the photoelectric conversion unit,

the photoelectric conversion unit including a first electrode, a second electrode, a photoelectric conversion layer disposed between the first electrode and the second electrode, and an insulating layer disposed between the photoelectric conversion layer and the second electrode,

the photoelectric conversion layer including quantum dots.

2. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion layer further includes a member formed of a material different from a material of the quantum dots, and

wherein the quantum dots are dispersed in the member.

3. The photoelectric conversion device according to claim 2, wherein the material of the member has a larger band gap than the material of the quantum dots.

4. The photoelectric conversion device according to claim 2, wherein the material of the quantum dots absorbs light having a longer wavelength than light having a longest wavelength that the material of the member absorbs.

5. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion layer further includes a cover layer configured to cover the quantum dots, and

wherein a material of the cover layer has a larger band gap than a material of the quantum dots.

6. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion layer further includes a cover layer configured to cover the quantum dots, and

wherein a material of the quantum dots absorbs light having a longer wavelength than light having a longest wavelength that a material of the cover layer absorbs.

7. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion layer further includes a buried layer in which the quantum dots are buried, and

wherein a material of the buried layer has a larger band gap than a material of the quantum dots.

8. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion layer further includes a buried layer in which the quantum dots are buried, and

wherein a material of the quantum dots absorbs light having a longer wavelength than light having a longest wavelength that a material of the buried layer absorbs.

9. The photoelectric conversion device according to claim 1, wherein the quantum dots include a quantum dot having a particle size in a range of 1 nm to 20 nm.

10. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion layer further includes a shell configured to surround the quantum dots.

11. The photoelectric conversion device according to claim 10, wherein a ratio of a lattice constant of a material of the quantum dots to a lattice constant of a material of the shell member is in a range of 0.9 to 1.1.

12. The photoelectric conversion device according to claim 1, wherein the quantum dots is formed of a material selected from the group consisting of PbS, PbSe, PbTe, CdS, CdSe, CdTe, C, Si, and Ge.

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

a reset unit configured to supply a reset voltage to the second electrode;

a first capacitor including a first terminal and a second terminal, the first terminal being electrically connected to the second electrode; and

a voltage supply unit configured to supply at least a first voltage and a second voltage different from the first voltage to the second terminal,

wherein the amplification unit is electrically connected to the second electrode, and

wherein the following relationship is satisfied;

15. The photoelectric conversion device according to claim 14, wherein the first voltage is supplied to the second terminal to accumulate signal charge in the photoelectric conversion layer, and

wherein the second voltage is supplied to the second terminal to discharge the signal charge from the photoelectric conversion layer.

16. The photoelectric conversion device according to claim 1, further comprising:

a reset unit configured to supply a reset voltage to the second electrode;

a first capacitor electrically connected to the second electrode; and

a voltage supply unit configured to supply at least a first voltage and a second voltage different from the first voltage to the first electrode,

wherein the amplification unit is electrically connected to the second electrode, and

wherein the following relationship is satisfied;

17. The photoelectric conversion device according to claim 16, wherein the first voltage is supplied to the first electrode to accumulate signal charge in the photoelectric conversion layer, and

wherein the second voltage is supplied to the first electrode to discharge the signal charge from the photoelectric conversion layer.

18. The photoelectric conversion device according to claim 14, wherein the first capacitor includes two electrodes facing each other.

19. An imaging system comprising:

the photoelectric conversion device according to claim 1; and

a signal processing device configured to process a signal from the photoelectric conversion device.

20. The imaging system according to claim 19, wherein two photoelectric conversion units, each comprising the photoelectric conversion unit, are disposed for each pixel, and

wherein the signal processing device processes a signal based on electric charge generated by the two photoelectric conversion units, and obtains information on a distance from the photoelectric conversion device to an object.

13. A photoelectric conversion device comprising:

a pixel,

the pixel including

a photoelectric conversion unit, and

an amplification unit configured to output a signal generated by the photoelectric conversion unit,

the photoelectric conversion unit including a first electrode, a second electrode, a photoelectric conversion layer disposed between the first electrode and the second electrode, and an insulating layer disposed between the photoelectric conversion layer and the second electrode,

the photoelectric conversion layer including a first member, and a plurality of particles arranged in the first member and having a particle size in a range of 1 nm to 20 nm.