JP4054612B2 - Radiation imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radiation detection apparatus that detects radiation such as X-rays and γ-rays. In particular, it is applied to medical image diagnostic apparatuses, nondestructive inspection apparatuses, analyzers using radiation, and the like.
[0002]
[Prior art]
Conventionally, photographing used for medical image diagnosis is roughly classified into general photographing for obtaining a still image and fluoroscopic photographing for obtaining a moving image. Each photographing method is selected including a photographing device as necessary.
[0003]
General photography, that is, a method of obtaining a still image is a method of fixing a film after exposing and developing the film using a screen film system (hereinafter referred to as “S / F”) that combines a fluorescent plate and a film, or After recording a radiographic image as a latent image on the photostimulable phosphor, the photostimulable phosphor is scanned with a laser, and the output light output information is read by a sensor (Computed Radiography, hereinafter referred to as “CR”). The method is common.
[0004]
However, in both methods, the workflow for obtaining a radiographic image may be complicated, and digitization is possible indirectly, but it lacks immediacy and is used in other medical imaging diagnosis, Considering a digitized environment such as MIR, it is difficult to say that the situation is consistent and sufficient.
[0005]
Further, for fluoroscopic imaging, that is, a moving image, an image intensifier using an electron tube (hereinafter referred to as “I.I”) is mainly used. However, since the electron tube is used, the apparatus becomes large-scale. In addition, the field of view, that is, the detection area is still small, and there is an urgent need to increase the area in the medical image diagnostic field.
[0006]
Furthermore, due to problems in the apparatus configuration, the obtained moving image has a lot of crosstalk, and an improvement to a clear image is expected.
[0007]
On the other hand, with the progress of liquid crystal TFT technology and the improvement of information infrastructure, photoelectric conversion elements and switch TFTs using non-single crystal silicon, for example, amorphous silicon (hereinafter referred to as “a-Si”). A flat panel detector (hereinafter referred to as “FPD”) that combines a sensor array configured by the above and a phosphor that converts radiation into visible light or the like has been proposed. The possibility of coming out.
[0008]
This FPD can read a radiation image instantly and display it on a display instantly, and since the image can be directly taken out as digital information, it can be stored, processed, transferred, etc. Is convenient. In addition, although various characteristics such as sensitivity depend on imaging conditions, it has been confirmed that they are equivalent to or higher than conventional S / F imaging methods and CR imaging methods.
[0009]
FIG. 8 is a schematic equivalent circuit diagram of a conventional FPD. In FIG. 8, 101 is a photoelectric conversion element portion, 102 is a switch TFT portion, 103 is a switch TFT drive wiring, 104 is a signal line, 105 is a bias wiring, 106 is a signal processing circuit, 107 is a TFT drive circuit, and 108 is an A / A D conversion unit.
[0010]
When radiation such as X-rays enters the FPD , it is converted into visible light by a phosphor (not shown). The converted light is converted into electric charge by the photoelectric conversion unit 101 and accumulated in the photoelectric conversion unit 101. After that, the TFT driving circuit 107 operates the switch TFT unit 102 from the TFT driving wiring 103 and transfers this accumulated charge to the signal processing circuit 106 through the signal line 104. After processing, the A / D conversion unit 108 performs A / D conversion. D-converted and output.
[0011]
Basically, the element configuration as described above is generally used. In particular, the photoelectric conversion unit 101 is a PIN type photodiode (hereinafter referred to as “PIN type PD”) or the present inventors have adopted. Various devices such as a MIS type photodiode (hereinafter referred to as “MIS type PD”) have been proposed.
[0012]
An FPD using a PIN type PD is disclosed in US Pat. No. 6,288,435 B1 as a structure capable of realizing a high aperture ratio and reducing a leakage current in a vertical direction or a horizontal direction.
[0013]
However, in the PIN type PD, for example, when a leak occurs in the vertical direction, that is, between the upper and lower sides due to particles in the I type a-Si layer, the P type or N type semiconductor layer is used. It appears in the horizontal direction, that is, as a continuous defect of a plurality of pixels, which has a great influence on peripheral pixels and is considered to affect image diagnosis. In other words, when an a-Si layer that requires a certain thickness as the photoelectric conversion layer is used, there is a serious drawback with respect to the above-mentioned problems that are difficult to avoid.
[0014]
In the above case, there is a laser repair method in which the transfer TFT of the problem pixel is removed to make a single pixel defect, and the output is corrected by the output of the adjacent pixel, but this method corrects the leak in the PIN type PD. Rather, the influence on surrounding pixels cannot be reduced.
[0015]
Further, when removing the cause of the leak in the PIN type PD directly, a simple laser causes a new leak from the processing side surface, and the influence on the peripheral pixels remains after all. That is, it can be said that there is a problem in the fundamental device structure that it is very difficult to realize even in production with high yield or in consideration of repair.
[0016]
On the other hand, since the MIS type PD has a simple manufacturing method and uses an insulating layer, for example, particles in the I type a-Si layer have little influence on peripheral pixels. There are features such as. Conventional examples are disclosed in Japanese Patent No. 3066944 and US Pat. No. 6,075,256 by the present inventors.
[0017]
FIG. 9 is a schematic plan view for one pixel of the photoelectric conversion unit (MIS type PD) of FIG. In FIG. 9, 201 is a MIS type PD lower electrode, 202 is a switch TFT drive wiring, 203 is a switch TFT gate electrode, 204 is a contact hole, 205 is a bias wiring, 206 is a signal line, and 207 is a switch TFT source / drain electrode. (Hereinafter referred to as “SD electrode”).
[0018]
10 is a schematic cross-sectional view of FIG. In FIG. 10, 301 is a glass substrate, 305 is a gate insulating layer, 306 is an intrinsic a-Si layer, 307 is a hole blocking layer, 320 is a protective layer, 321 is an organic resin layer, and 322 is a phosphor layer.
[0019]
11A to 11E are manufacturing process diagrams of the MIS type PD shown in FIG.
[0020]
First, the switch TFT drive wiring 202, the MIS type PD lower electrode 201, and the switch TFT gate electrode 203 are formed on the glass substrate 301 (FIG. 11A).
[0021]
Second, a gate insulating layer 305, an intrinsic a-Si layer 306, and a hole blocking layer 307 are sequentially stacked.
[0022]
Third, a contact hole 204 for joining the MIS type PD lower electrode 201 and the SD electrode 207 of the switch TFT is formed (FIG. 11B).
[0023]
Fourth, a metal layer is stacked, and the bias wiring 205 is formed by the first resist work. At this time, a region where a switch TFT SD electrode 207 and a signal line 206 to be described later are formed is left in an island shape (FIG. 11C).
[0024]
Fifth, the switch TFT SD electrode 207 and the signal line 206 are formed by the second resist work, and then the n ⁺ semiconductor layer is removed. That is, a gap portion between the SD electrodes of the switch TFT is formed, and at the same time, the n ⁺ semiconductor layer of the MIS PD portion is left as an electrode (FIG. 11D).
[0025]
Sixth, element isolation is performed (FIG. 11E).
[0026]
Seventh, a protective layer 320 is stacked, and a necessary region such as a wiring lead portion is removed.
[0027]
Thereafter, the phosphor layer 322 is bonded with the organic resin layer 321.
[0028]
As shown in FIGS. 9 and 10, the FPD manufactured as described above has the same layer structure as the MIS type PD and the switch TFT. Therefore, the manufacturing method is simple, high yield, and low price can be realized. In addition, it is evaluated that various characteristics such as sensitivity can be sufficiently satisfied.
[0029]
For this reason, as a device used for general photography, the above-described FPD has been adopted instead of the conventional S / F method and CR method.
[0032]
[Problems to be solved by the invention]
However, the conventional techniques have the following problems. In other words, the conventional FPD has a large area and is fully digitalized, and is gradually beginning to be used mainly for general photography. However, further improvement is expected in terms of sensitivity. Further, in order to enable fluoroscopic imaging, it is considered essential to further improve sensitivity.
[0033]
In the FPD, since the MIS type PD and the switch TFT have the same layer configuration, they can be simultaneously produced in the same process. That is, since the manufacturing method is simple, there is an advantage that it can be realized with high yield, high quality, and low price.
[0034]
However, since the elements are formed on the same plane in principle, there is a problem that the aperture ratio is improved, in other words, the sensitivity is limited.
[0035]
The sensitivity of the MIS type PD is proportional to the internal gain represented by C _INS / (C _INS + C _SEMI ), where C _INS is the capacitance of the insulating layer and C _SEMI is the capacitance of the semiconductor layer. In other words, increasing the thickness of the semiconductor layer or reducing the thickness of the insulating layer is a desirable direction for improving sensitivity.
[0036]
On the other hand, the transfer capability of the switch TFT, that is, the ON resistance is improved in accordance with the thinning of the semiconductor layer in the normal range. This is presumed to be because the parasitic resistance formed under the source / drain electrodes is reduced.
[0037]
In principle, the insulating layer is thinned to improve the transfer capability of the switch TFT, but the step coverage at a step at a wiring intersection or the like is lowered. As a result, the insulating layer thickness is determined in consideration of the yield.
[0038]
That is, the thickness of the semiconductor layer that satisfies both the characteristics of the MIS type PD and the switch TFT in a well-balanced manner and the thickness of the insulating layer in consideration of the yield are determined. As a result, the TFT size becomes large, the aperture ratio of the MIS type PD is compressed, and there is a problem that the characteristics of each element have to use compromised performance.
[0039]
Therefore, the present invention proposes a device configuration capable of independently improving both the device characteristics of the MIS type PD and the switch TFT in the FPD using the MIS type PD, and achieves further improvement in sensitivity. This is the issue.
[0040]
[Means for Solving the Problems]
In order to solve the above problems, the present invention includes a wavelength converter for converting radiation into visible light, the pixel electrodes for converting the visible light into an electric signal, a photoelectric conversion element that includes a semi-conductor layer, wherein a transistor for controlling the readout of the electric signal converted by the photoelectric conversion element, a radiation imaging apparatus provided respectively, the photoelectric conversion elements are arranged by laminating a wavelength conversion body side of said transistor, said pixel electrode and is divided for each pixel, the semiconductor layer is placed to extend over a plurality of pixels, on the semiconductor layer on between the adjacent pixel electrodes, application of a bias voltage to the photoelectric conversion element and A bias wiring for preventing the visible light from flowing into adjacent pixels is disposed, and the width of the bias wiring is larger than the distance between adjacent pixel electrodes .
[0041]
The radiation detection system of the present invention includes a radiation imaging apparatus.
[0042]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0043]
(Embodiment 1)
[Description of configuration]
FIG. 1 is a schematic plan view of an X-ray detection apparatus using a MIS type PD according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. 3 is a schematic cross-sectional view taken along the line BB in FIG.
[0044]
1 to 3, 1 is an insulating substrate, 2 is a gate electrode of a switch TFT, 3 is a gate wiring connected to a gate electrode 2 which is a third electrode, 4 is a first insulating layer, and 5 is a first electrode. The semiconductor layer, 6 is a first ohmic contact layer, 7 is a switch TFT source / drain electrode, 8 is a signal line connected to the source / drain electrode 7, 9 is a first planarization layer, and 10 is a contact hole. , 11 is a pixel electrode of MIS type PD, 12 is a second insulating layer, 13 is a second semiconductor layer, 14 is a second ohmic contact layer, 15 is a transparent electrode layer, 16 is a bias wiring of MIS type PD, Reference numeral 17 denotes a second planarizing layer, 18 denotes an adhesive layer, and 19 denotes a phosphor layer.
[0045]
In the present embodiment, X-rays are converted into visible light by the phosphor layer 19 and enter the second semiconductor layer 13 of the MIS type PD. Incident light is photoelectrically converted by the second semiconductor layer 13 and accumulated in the MIS type PD. Thereafter, an ON voltage is applied from the gate wiring 3, the switch TFT is turned on, and the output voltage is read out via the signal line 8. Thereafter, a reset voltage is applied to the MIS type PD unit from the bias wiring 16 to reset the charge accumulated in the PD.
[0046]
As shown in FIGS. 1 to 3, the pixel electrode 11 of the MIS type PD is disposed so as to overlap the gate line 3 and the signal line 8. Further, the second insulating layer 12, the second semiconductor layer 13, and the second ohmic contact layer 14 of the MIS type PD are stacked over the entire pixel region. As a result, the aperture ratio can be greatly improved.
[0047]
That is, most of the converted light from the phosphor layer 19 is incident on the second semiconductor layer 13 and is photoelectrically converted, and the converted charge can be collected by the pixel electrode 11 of the MIS type PD. . For example, in the case of a pixel size of 160 μm, the aperture ratio has been improved by about 1.5 times compared to the conventional case.
[0048]
Furthermore, as can be confirmed from the manufacturing method described later, since the layer configuration of the switch TFT and the layer configuration of the MIS type PD can be realized differently, the internal gain of the MIS type PD is improved by about 1.5 times. Combined with the improvement in the aperture ratio described above, an improvement of about twice or more has become possible.
[0049]
Further, the transfer capability of the switch TFT is at least 10 times or more, and the TFT size can be reduced. As a result, the parasitic capacitance depending on the TFT size is reduced, and noise can be reduced.
[0050]
4A to 4F are schematic manufacturing process diagrams of the FPD of FIG.
[0051]
First, on the insulating substrate 1, a stack composed of a 2500-thick Al—Nd thin layer and a 300-thick Mo thin layer to be the gate electrode 2 and the gate wiring 3 of the switch TFT is formed by a sputtering apparatus. Form.
[0052]
Secondly, the gate wiring 3 for driving the switch TFT and the gate electrode 2 are pattern-formed by photolithography using wet etching (FIG. 4A).
[0053]
Third, the SiN layer that becomes the first insulating layer 4, the a-Si layer that becomes the first semiconductor layer 5, and the phosphorus-doped n ⁺ type layer that becomes the first ohmic contact layer 6 are each formed by a plasma CVD apparatus. It is formed with a thickness of 2500 mm, 1000 mm, and 200 mm.
[0054]
Fourth, as a metal layer to be the source / drain electrode 7 of the switch TFT, a Mo layer 500 Å, an Al layer 4000 Å, and a Mo layer 300 Å are formed by a sputtering apparatus.
[0055]
Fifth, the source / drain electrodes 7 and the signal lines 8 of the switch TFT are formed by photolithography using wet etching. Subsequently, the n ⁺ layer in the channel portion of the switch TFT is removed by the RIE method with the same resist pattern (FIG. 4B).
[0056]
Sixth, the first insulating layer 4, the first semiconductor layer 5, and the first ohmic contact layer 6 are removed by photolithography using RIE or CDE, and element isolation is performed (FIG. 4). (C)).
[0057]
The above is the manufacturing process for producing the switch TFT.
[0058]
Subsequently, a process of stacking the MIS type PD on the switch TFT will be described.
[0059]
Seventh, planarization is performed using the first planarization layer 9, in this embodiment, BCB (benzocyclobutene) manufactured by Dow Chemical. This member has a dielectric constant of about 2.6, which is much lower than that of a normal SiN layer of about 6.0, and the parasitic capacitance of the gate wiring 3 or the signal line 8 and a pixel electrode 11 described later. Can be reduced.
[0060]
Eighth, a contact hole 10 is formed in the first planarizing layer 9 by photolithography using RIE or CDE (FIG. 4D).
[0061]
Ninth, a Mo layer with a thickness of 500 mm, an Al layer with a thickness of 2000 mm, and a Mo layer with a thickness of 300 mm are formed by a sputtering apparatus to be the pixel electrode 11.
[0062]
Tenth, the pixel electrode 11 of the MIS type PD portion is formed by a photolithography method using wet etching (FIG. 4E).
[0063]
In FIG. 4E, the switch TFT and each wiring are omitted for convenience of explanation.
[0064]
Eleventh, the SiN layer as the second insulating layer 12, the a-Si layer as the second semiconductor layer 13, and the phosphorus-doped n ⁺ -type layer as the second ohmic contact layer 14 are obtained by using a plasma CVD apparatus, respectively, for 1500Å and 6000Å. , With a thickness of 200 mm. Subsequently, a transparent electrode layer 15 such as ITO is formed to a thickness of 400 mm.
[0065]
Twelfth, a 500-thickness Mo layer, a 4000-thickness Al layer, and a 300-thickness Mo layer, which become the bias wiring 16 of the MIS type PD, are formed by a sputtering apparatus.
[0066]
13th, the bias wiring 16 of MIS type | mold PD is formed by the photolithographic method using the wet etching method (FIG.4 (f)).
[0067]
14th, BCB is apply | coated as the 2nd planarization layer 17, and a SiN layer is formed with a thickness of 3000 と し て as a final protective layer.
[0068]
Fifteenth, the extraction electrode portion and the like are exposed by a photolithography method using an RIE method or a CDE method.
[0069]
Sixteenth, the phosphor layer 19 is bonded with the adhesive layer 18.
[0070]
As described above, the FPD of this embodiment is manufactured.
[0071]
As described above, the switch TFT and the MIS type PD have a laminated structure through the interlayer insulating layer, so that the improvement of the switch TFT characteristic and the improvement of the MIS type PD characteristic can be achieved at the same time. The influence on the generation of particles of the a-Si layer that cannot be avoided is reduced. For this reason, the X-ray detection apparatus of the present embodiment can be advantageously and easily realized in production, and a semiconductor layer having a photoelectric conversion function is provided to extend over a plurality of pixels. Therefore, the efficiency can be increased.
[0072]
(Embodiment 2)
In the second embodiment of the present invention, an X-ray detection apparatus using a MIS type PD will be described.
[0073]
FIG. 5 is a schematic cross-sectional view of the X-ray detection apparatus according to the second embodiment of the present invention. In FIG. 5, the same parts as those shown in FIG.
[0074]
Hereinafter, a method for manufacturing the FPD of this embodiment will be described.
[0075]
The first to eighth steps are the same as those in the first embodiment.
[0076]
Ninth, as the second ohmic contact layer 14 of the MIS type PD, a phosphorus doped n ⁺ type layer is formed with a thickness of 1000 mm by a plasma CVD apparatus.
[0077]
Tenth, the second ohmic contact layer 14 is formed as the pixel electrode 11 of the MIS type PD in the first embodiment by a photolithography method using the RIE method or the CDE method.
[0078]
Eleventh, an a-Si layer as the second semiconductor layer 13 and an SiN layer as the second insulating layer 12 are formed with a thickness of 6000 mm and 1500 mm, respectively, by a plasma CVD apparatus. Thereafter, a transparent electrode layer 15 such as ITO is formed with a thickness of 400 mm.
[0079]
12th, it becomes the bias wiring 16 of MIS type | mold PD. A 500-thick Mo layer, a 4000-thick Al layer, and a 300-thick Mo layer are formed by a sputtering apparatus.
[0080]
13th, the bias wiring 16 of MIS type PD is formed by the photolithographic method using the wet etching method.
[0081]
14th, BCB is apply | coated as the 2nd planarization layer 17, and a SiN layer is formed with a thickness of 3000 と し て as a final protective layer.
[0082]
Fifteenth, the extraction electrode portion and the like are exposed by a photolithography method using an RIE method or a CDE method.
[0083]
Sixteenth, the phosphor layer 19 is bonded with the adhesive layer 18.
[0084]
As described above, the FPD of this embodiment is manufactured.
[0085]
In the present embodiment, as described above, the second ohmic contact layer 14 is used as the pixel electrode 11 in the first embodiment, and it is necessary to increase the thickness in consideration of the resistance value. However, thickening may not be possible depending on the manufacturing apparatus. In that case, it can be used in combination with other conductive layers. That is, after the eighth step, it is possible to form a conductive layer, form the pixel electrode 11, and then manufacture from the ninth step. Also in this embodiment, since the semiconductor layer having a photoelectric conversion function is provided so as to extend over a plurality of pixels, efficiency can be increased.
[0086]
(Embodiment 3)
In Embodiment 3 of the present invention, an X-ray detection apparatus using a MIS type PD will be described. In the present embodiment, the spatial resolution is improved by devising the arrangement of the bias wiring.
[0087]
FIG. 6 is a schematic plan view of an X-ray detection apparatus according to Embodiment 3 of the present invention. As shown in FIG. 6, in this embodiment, in the 2 × 2 pixel, the bias wiring 16 is arranged between the pixel electrodes 11 of the adjacent MIS type PDs.
[0088]
For this reason, when the converted light from the phosphor layer 19 enters the MIS type PD, the bias wiring 16 prevents the inflow of light from the adjacent pixels, so that the spatial resolution is improved.
[0089]
(Embodiment 4)
FIG. 7 is a schematic plan view of the X-ray detection system according to the fourth embodiment of the present invention.
[0090]
X-rays 6060 generated by the X-ray tube 6050 pass through the chest 6062 of the patient or subject 6061 and enter the photoelectric conversion device 6040 having the phosphor mounted thereon. This incident X-ray includes information inside the body of the patient 6061. The phosphor emits light in response to the incidence of X-rays, and this is photoelectrically converted to obtain electrical information. This information is converted to digital, image processed by an image processor 6070, and can be observed on a display 6080 in the control room.
[0091]
Further, this information can be transferred to a remote place by a transmission means such as a telephone line 6090 and can be displayed on a display 6081 such as a doctor room in another place or stored in a storage means such as an optical disk, and a doctor at a remote place makes a diagnosis. It is also possible. It can also be recorded on the film 6110 by the film processor 6100.
[0092]
【The invention's effect】
As described above, according to the present invention, in the FPD using the MIS type PD, a device configuration capable of independently improving both the device characteristics of the MIS type PD and the switch TFT is proposed. , Sensitivity improvement can be achieved.
[Brief description of the drawings]
FIG. 1 is a schematic plan view of an X-ray detection apparatus using a MIS type PD according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view taken along a line AA in FIG.
FIG. 3 is a schematic cross-sectional view taken along a line BB in FIG.
4 is a schematic manufacturing process diagram of the FPD of FIG. 1; FIG.
FIG. 5 is a schematic cross-sectional view of an X-ray detection apparatus according to a second embodiment of the present invention.
FIG. 6 is a schematic plan view of an X-ray detection apparatus according to a third embodiment of the present invention.
FIG. 7 is a schematic plan view of an X-ray detection system according to a fourth embodiment of the present invention.
FIG. 8 is a schematic equivalent circuit diagram of a conventional FPD.
9 is a schematic plan view for one pixel of the photoelectric conversion unit (MIS type PD) in FIG. 8;
10 is a schematic cross-sectional view of FIG. 9. FIG.
11 is a manufacturing process diagram of the MIS type PD shown in FIG. 9; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Gate electrode 3 of switching TFT Gate wiring 4 connected to gate electrode 2 First insulating layer 5 First semiconductor layer 6 First ohmic contact layer 7 Switch TFT source / drain electrode 8 Source / drain electrode Signal line 9 connected to the first planarizing layer 10 contact hole 11 pixel electrode 12 of MIS type PD second insulating layer 13 second semiconductor layer 14 second ohmic contact layer 15 transparent electrode layer 16 MIS type PD bias wiring 17 Second planarization layer 18 Adhesive layer 19 Phosphor layer

Claims (7)

A wavelength converter for converting radiation into visible light, the pixel electrodes for converting the visible light into an electric signal, a photoelectric conversion element that includes a semi-conductor layer, the reading of the electric signal converted by the photoelectric conversion element A radiation imaging apparatus provided with each of the transistors to be controlled;
The photoelectric conversion elements are arranged by laminating the wavelength conversion side of the transistor, the pixel electrode and is divided for each pixel, the semiconductor layer is placed to extend over a plurality of pixels,
On the semiconductor layer between adjacent pixel electrodes, a bias wiring for applying a bias voltage to the photoelectric conversion element and preventing inflow of the visible light to adjacent pixels is disposed,
A radiation imaging apparatus, wherein a width of the bias wiring is larger than a distance between adjacent pixel electrodes . The pixel electrode is disposed so as to be located on a part of a signal line connected to the source or drain of the transistor and transmitting the electric signal and a part of a wiring connected to the control electrode of the transistor. The radiation imaging apparatus according to claim 1, wherein: Wherein a photoelectric conversion element is an insulating layer, from the radiation incident side, the semiconductor layer, the radiation imaging apparatus according to claim 1 or 2, characterized in that it is arranged in the order of the insulating layer. The photoelectric conversion element further has an insulating layer, from the radiation incident side, the insulating layer, the radiation imaging apparatus according to claim 1 or 2, characterized in that it is arranged in the order of the semiconductor layer. The radiation imaging apparatus according to claim 4, wherein the pixel electrode is an ohmic contact layer. Furthermore, radiation imaging apparatus according to any one of claims 1-5, characterized in that it comprises a transparent electrode layer on the radiation incident side of the photoelectric conversion element. The radiation detection system comprising a radiation imaging apparatus according to any one of claims 1 6.

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