Photoelectric conversion device and imaging system
A photoelectric conversion device includes a photoelectric conversion unit including a first and second electrodes, a photoelectric conversion layer between the first and second electrodes, and an insulating layer between the photoelectric conversion layer and the second electrodes, an amplifier unit connected to the second electrode and outputs a signal generated in the photoelectric conversion unit, and a reset unit for resetting a voltage of the second electrode. An accumulating operation for accumulating signal charges in the photoelectric conversion unit and a charge removing operation for removing the signal charges from the photoelectric conversion unit are alternately executed in accordance with a voltage applied between the first and second electrodes, and the charge removing operation is executed multiple times between a first accumulating operation and a second accumulating operation which is executed after the first accumulating operation.
1. A photoelectric conversion device comprising:
a photoelectric conversion unit including a first electrode, a second electrode, a photoelectric conversion layer arranged between the first electrode and the second electrode, and an insulating layer arranged between the photoelectric conversion layer and the second electrode;
an amplifier unit electrically connected to the second electrode and configured to output a signal generated in the photoelectric conversion unit; and
a reset unit configured to supply a reset voltage to the second electrode, wherein
in accordance with a voltage applied between the first electrode and the second electrode, an accumulating operation for accumulating signal charges in the photoelectric conversion unit and a charge removing operation for removing the signal charges accumulated by the accumulating operation from the photoelectric conversion unit are alternately executed, and
the charge removing operation is executed multiple times between a first accumulating operation and a second accumulating operation which is executed after the first accumulating operation, the accumulating operation being executed multiple times including the first and second accumulating operations.
2. The photoelectric conversion device according to claim 1 , wherein
the amplifier unit outputs the signal during the charge removing operation executed multiple times.
3. The photoelectric conversion device according to claim 2 , wherein
the reset unit resets the second electrode synchronously with the charge removing operation which is executed at or after a second time in the charge removing operation executed multiple times.
4. The photoelectric conversion device according to claim 3 , further comprising:
a first capacitor including a first terminal electrically connected to the second electrode and a second terminal; 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
a voltage Vs supplied to the first electrode, the first voltage Vd 1 , the second voltage Vd 2 , the reset voltage Vres, a capacitance value C 1 of the first capacitor, and a capacitance value C 2 of a second capacitor which is formed by the first electrode and the second electrode satisfy a relation shown by the following expression:
C 1/( C 1+ C 2)>( Vs−Vres )/( Vd 2 −Vd 1).
5. The photoelectric conversion device according to claim 4 , wherein
when the signal charges are accumulated in the photoelectric conversion layer, the first voltage is supplied to the second terminal, and
when the signal charges are removed from the photoelectric conversion layer, the second voltage is supplied to the second terminal.
6. The photoelectric conversion device according to claim 4 , wherein
a difference between the voltage supplied to the first electrode and the reset voltage lies within a range of 20% to 80% of a difference between the first voltage and the second voltage.
7. The photoelectric conversion device according to claim 3 , further comprising:
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 first voltage Vs 1 , the second voltage Vs 2 , the reset voltage Vres, a capacitance value C 1 of the first capacitor, and a capacitance value C 2 of a second capacitor which is formed by the first electrode and the second electrode satisfy a relation shown by the following expression:
C 1/ C 2>( Vres−Vs 1)/( Vs 2 −Vres ).
8. The photoelectric conversion device according to claim 7 , wherein
when the signal charges are accumulated in the photoelectric conversion layer, the first voltage is supplied to the first electrode, and
when the signal charges are removed from the photoelectric conversion layer, the second voltage is supplied to the first electrode.
9. The photoelectric conversion device according to claim 7 , wherein
the reset voltage is an intermediate value between the first voltage and the second voltage.
10. The photoelectric conversion device according to claim 7 , wherein
the first capacitor includes a first terminal electrically connected to the second electrode and a second terminal, and
the second terminal is grounded.
11. The photoelectric conversion device according to claim 4 , wherein
the first capacitor includes two electrodes which face each other,
when seen as a plan view, the two electrodes and the first electrode overlap with each other at least partially, and
when seen as a plan view, the two electrodes and the second electrode overlap with each other at least partially.
12. The photoelectric conversion device according to claim 4 , wherein
an input node of the amplifier unit is configured to include the second electrode.
13. The photoelectric conversion device according to claim 4 , wherein
a switch is arranged on an electric path between the second electrode and the first capacitor.
14. The photoelectric conversion device according to claim 4 , wherein
a switch is arranged on an electric path between the first capacitor and the amplifier unit.
15. The photoelectric conversion device according to claim 7 , wherein
the first capacitor includes two electrodes which face each other,
when seen as a plan view, the two electrodes and the first electrode overlap with each other at least partially, and
when seen as a plan view, the two electrodes and the second electrode overlap with each other at least partially.
16. The photoelectric conversion device according to claim 7 , wherein
an input node of the amplifier unit is configured to include the second electrode.
17. The photoelectric conversion device according to claim 7 , wherein
a switch is arranged on an electric path between the second electrode and the first capacitor.
18. The photoelectric conversion device according to claim 7 , wherein
a switch is arranged on an electric path between the first capacitor and the amplifier unit.
19. The photoelectric conversion device according to claim 1 , wherein
the device includes a plurality of pixels each including the photoelectric conversion unit,
the first electrode is provided in common for the plurality of pixels, and
the second electrode is individually provided for each of the plurality of pixels.
20. An imaging system comprising:
the photoelectric conversion device according to claim 1 ; and
a signal processing apparatus configured to process a signal from the photoelectric conversion device.