Radiation detection apparatus and radiation detection system

1. A radiation detection apparatus including a plurality of pixels, the apparatus comprising:

conversion elements including a first electrode, a semiconductor layer, and a second electrode that are divided for each pixel;

switching elements electrically connected to the first electrodes; and

a first insulating layer that separates the conversion elements of adjacent pixels,

wherein the semiconductor layer is located between the first electrode and the second electrode,

a periphery of the semiconductor layer is located outside a periphery of the first electrode and a periphery of the second electrode,

the semiconductor layer includes a first impurity semiconductor layer including a portion in contact with the first electrode, a second impurity semiconductor layer including a portion in contact with the second electrode, and an intrinsic semiconductor layer located between the first impurity semiconductor layer and the second impurity semiconductor layer, and

a length D L1 from a periphery of the first impurity semiconductor layer along the first impurity semiconductor layer up to the portion, in contact with the first electrode, of the first impurity semiconductor layer, a length D U from a periphery of the second impurity semiconductor layer along the second impurity semiconductor layer up to the portion, in contact with the second electrode, of the second impurity semiconductor layer, a sheet resistance R □L1 of the first impurity semiconductor layer, a sheet resistance R □U of the second impurity semiconductor layer, a pixel pitch P of the plurality of pixels, and an ON resistance R on of the switching element are defined to set a residual charge 10 μs after the switching element is turned on to be not higher than 2%.

2. The apparatus according to claim 1 , wherein

{ D L1 /(4 ×P )}× R □L1 <5 ×R on , and

{ D U /(4 ×P )}× R □U <100 ×R on

are satisfied.

3. The apparatus according to claim 1 , wherein a length from the periphery of the first electrode to the periphery of the semiconductor layer is not smaller than 5 nm.

4. The apparatus according to claim 1 , wherein a length from the periphery of the first electrode to the periphery of the semiconductor layer is not smaller than 1 μm.

5. The apparatus according to claim 1 , wherein a length from the periphery of the second electrode to the periphery of the semiconductor layer is not smaller than 5 nm.

6. The apparatus according to claim 1 , wherein a length from the periphery of the second electrode to the periphery of the semiconductor layer is not smaller than 1 μm.

7. The apparatus according to claim 1 , wherein the periphery of the first impurity semiconductor layer contacts the first insulating layer.

8. The apparatus according to claim 1 , wherein the first impurity semiconductor layer and the first insulating layer are separated from each other by the intrinsic semiconductor layer.

9. The apparatus according to claim 8 , wherein letting D L3 be a length from the periphery of the first impurity semiconductor layer to a periphery of the intrinsic semiconductor layer, and R □L3 be a sheet resistance of the intrinsic semiconductor layer,

{D L1 /(4 ×P )}× R □L1 +{D L3 /(4 ×P )}× R □L3 <5 ×R on

is further satisfied.

10. The apparatus according to claim 1 , further comprising a second insulating layer that separates the periphery of the first electrode and the first impurity semiconductor layer from each other.

11. The apparatus according to claim 1 , further comprising a scintillator layer that is arranged on the plurality of pixels and converts a radiation into light of a wavelength detectable by the conversion element.

12. A radiation detection system comprising:

a radiation detection apparatus defined in claim 1 ; and

a signal processing unit for processing a signal obtained by the radiation detection apparatus.