Photodetector
A photodetector includes: a semiconductor substrate including first and second impurity regions; a gate insulating layer located on a region of the semiconductor substrate, the region being between the first and second impurity regions, the gate insulating layer including a photoelectric conversion layer; a gate electrode located on the gate insulating layer and having a light-transmitting property; a first charge transfer channel transferring signal charges corresponding to a current occurring between the first impurity region and the second impurity region depending on a change in a dielectric constant of the photoelectric conversion layer caused by light incidence on the photoelectric conversion layer; a second charge transfer channel diverging from the first charge transfer channel; a first charge storage storing charges, among the signal charges, transferred via the second charge transfer channel; and a first gate switching transfer and shutdown of charges passing through the second charge transfer channel.
1. A photodetector comprising:
a semiconductor substrate including a first impurity region and a second impurity region;
a gate insulating layer located on a region of the semiconductor substrate, the region being between the first impurity region and the second impurity region, the gate insulating layer including a photoelectric conversion layer;
a gate electrode located on the gate insulating layer and having a light-transmitting property;
a first charge transfer channel transferring signal charges corresponding to a current occurring between the first impurity region and the second impurity region depending on a change in a dielectric constant of the photoelectric conversion layer caused by light incidence on the photoelectric conversion layer;
a second charge transfer channel diverging from the first charge transfer channel;
a first charge storage storing charges, among the signal charges, transferred via the second charge transfer channel; and
a first gate switching transfer and shutdown of charges passing through the second charge transfer channel.
2. The photodetector according to claim 1 , wherein the gate insulating layer includes an insulating layer between the photoelectric conversion layer and the semiconductor substrate.
3. The photodetector according to claim 1 , further comprising:
a light shielding film between the gate electrode and the semiconductor substrate.
4. The photodetector according to claim 1 , wherein the photoelectric conversion layer has a photocurrent characteristic between a bias voltage applied to the photoelectric conversion layer and an current density of a current flowing through the photoelectric conversion layer, the photocurrent characteristic including a first voltage range where an absolute value of the current density increases as the bias voltage increases in a reverse direction, a second voltage range where the current density increases as the bias voltage increases in a forward direction, and a third voltage range where an absolute value of a rate of change of the current density relative to bias voltage is less than in the first voltage range and the second voltage range, the third voltage range being between the first voltage range and the second voltage range.
5. The photodetector according to claim 4 , further comprising:
a voltage supply circuit supplying a voltage that falls within the third voltage range when a voltage of the first impurity region is regarded as a standard, to the gate electrode, wherein
the current occurs between the first impurity region and the second impurity region in a state where a potential difference between the first impurity region and the gate electrode is maintained within the third voltage range.
6. The photodetector according to claim 4 , further comprising:
a voltage supply circuit, wherein
the voltage supply circuit supplies a voltage to the gate electrode such that a bias voltage that falls within the third voltage range is applied to the photoelectric conversion layer; and
the current occurs between the first impurity region and the second impurity region in a state where the bias voltage applied to the photoelectric conversion layer is maintained within the third voltage range.
7. The photodetector according to claim 1 , further comprising:
a voltage supply circuit, wherein
the semiconductor substrate includes a third impurity region;
one end of the first charge transfer channel is connected to the second impurity region, and the other end of the first charge transfer channel is connected to the third impurity region; and
the voltage supply circuit supplies a voltage different from a voltage of the first impurity region to the third impurity region.
8. The photodetector according to claim 1 , further comprising:
a third charge transfer channel diverging from the first charge transfer channel; and
a second charge storage storing charges, among the signal charges, transferred via the third charge transfer channel.
9. The photodetector according to claim 8 , further comprising:
a second gate switching transfer and shutdown of charges passing through the third charge transfer channel, wherein
the first gate and the second gate each independently switch transfer and shutdown of charges.
10. A photodetector comprising:
a semiconductor substrate including a first impurity region and a second impurity region;
a gate insulating layer located on a region of the semiconductor substrate, the region being between the first impurity region and the second impurity region;
a gate electrode on the gate insulating layer;
a first electrode electrically connected to the gate electrode;
a second electrode facing the first electrode and having a light-transmitting property;
a photoelectric conversion layer between the first electrode and the second electrode;
a first charge transfer channel transferring signal charges corresponding to a current occurring between the first impurity region and the second impurity region depending on a change in a dielectric constant between the first electrode and the second electrode caused by light incidence on the photoelectric conversion layer;
a second charge transfer channel diverging from the first charge transfer channel;
a first charge storage storing charges, among the signal charges, transferred via the second charge transfer channel; and
a first gate switching transfer and shutdown of charges passing through the second charge transfer channel.
11. The photodetector according to claim 10 , wherein the photoelectric conversion layer has a photocurrent characteristic between a bias voltage applied to the photoelectric conversion layer and an current density of a current flowing through the photoelectric conversion layer, the photocurrent characteristic including a first voltage range where an absolute value of the current density increases as the bias voltage increases in a reverse direction, a second voltage range where the output current density increases as the bias voltage increases in a forward direction, and a third voltage range where an absolute value of a rate of change of the current density relative to bias voltage is less than in the first voltage range and the second voltage range, the third voltage range being between the first voltage range and the second voltage range.
12. The photodetector according to claim 11 , further comprising:
a voltage supply circuit supplying a voltage that falls within the third voltage range when a voltage of the first impurity region is regarded as a standard, to the second electrode, wherein
the current occurs between the first impurity region and the second impurity region in a state where a potential difference between the first impurity region and the second electrode is maintained within the third voltage range.
13. The photodetector according to claim 11 , further comprising:
a voltage supply circuit, wherein
the voltage supply circuit supplies a voltage to the second electrode such that a bias voltage that falls within the third voltage range is applied to the photoelectric conversion layer; and
the current occurs between the first impurity region and the second impurity region in a state where the bias voltage applied to the photoelectric conversion layer is maintained within the third voltage range.
14. The photodetector according to claim 10 , further comprising:
a first insulating layer between the first electrode and the photoelectric conversion layer and/or a second insulating layer between the photoelectric conversion layer and the second electrode.
15. The photodetector according to claim 14 , further comprising:
a voltage supply circuit supplying a voltage that falls within the first voltage range when a voltage of the first impurity region is regarded as a standard, to the second electrode, wherein
the current occurs between the first impurity region and the second impurity region in a state where a potential difference between the first impurity region and the second electrode is maintained within the first voltage range.
16. The photodetector according to claim 10 , wherein the first electrode has a light-shielding property.
17. The photodetector according to claim 10 , further comprising:
a junction connecting between the gate electrode and the first electrode.
18. The photodetector according to claim 10 , further comprising:
a third charge transfer channel diverging from the first charge transfer channel; and
a second charge storage storing charges, among the signal charges, transferred via the third charge transfer channel.
19. The photodetector according to claim 18 , further comprising:
a second gate switching transfer and shutdown of charges passing through the third charge transfer channel, wherein
the first gate and the second gate each independently switch transfer and shutdown of charges.
20. The photodetector according to claim 10 , further comprising:
a voltage supply circuit, wherein
the semiconductor substrate includes a third impurity region;
one end of the first charge transfer channel is connected to the second impurity region, and the other end of the first charge transfer channel is connected to the third impurity region; and
the voltage supply circuit supplies a voltage different from a voltage of the first impurity region to the third impurity region.