Electromagnetic wave detecting element

The present invention is to provide an electromagnetic wave detecting element that can suppress the trapping of charges in a semiconductor layer. Plural lower electrodes, which collect charges generated in the semiconductor layer, are each provided to cover at least a portion in a length direction and the entire region in a width direction of a scan line adjacent thereto, and the lower electrodes are disposed at positions at which the scan lines are provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent Application No. 2008-093856, the disclosure of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electromagnetic wave detecting element. In particular, the present invention relates to an electromagnetic wave detecting element that includes plural collection electrodes that collect charges generated in a semiconductor layer by electromagnetic waves being irradiated.

2. Description of the Related Art

Radiation image detection devices such as FPDs (flat panel detectors), in which an X-ray sensitive layer is disposed on a TFT (thin film transistor) active matrix substrate and that can convert X-ray information directly into digital data, and the like, have been put into practice in recent years. As compared with a conventional imaging plate, an image can be confirmed immediately at an FPD. Further, the FPD has the advantage that video images as well can be confirmed. Therefore, the popularization of FPDs has advanced rapidly.

Various types of radiation image detection devices are proposed. For example, there is a direct-conversion-type radiation image detection device that converts radiation directly into charges and accumulates the charges. Moreover, there is an indirect-conversion-type radiation image detection device that once converts radiation into light at a scintillator of CsI:Tl, GOS (Gd2O2S:Tb), or the like, and, at semiconductor layer, converts the converted light into charges and accumulates the charges.

As an example,FIG. 8shows a plan view illustrating the constitution of a single pixel unit of a direct-conversion-type electromagnetic wave detecting element10′. Further, a cross-sectional view along line A-A ofFIG. 8is shown inFIG. 9.

As shown inFIG. 8, the electromagnetic wave detecting element10′ is provided with sensor portions103′ and TFT switches4′, which correspond with intersection portions of plural scan lines101′ and plural signal lines3′, which are disposed to intersect one another.

As shown inFIG. 9, the sensor portion103′ includes a semiconductor layer6′, an upper electrode7′ and a lower electrode11′. The semiconductor layer6′ generates charge when irradiated with X-rays. The upper electrode7′ applies a bias voltage to the semiconductor layer6′, and the lower electrode11′ collects the charge generated in the semiconductor layer6′.

For example, when X-rays are irradiated from the upper side ofFIG. 9, the semiconductor layer6′ generates charges thereinside. If a positive bias voltage is applied to the upper electrode7′ such that the upper electrode7′ is at a positive potential relative to the lower electrode11′, then among the charges generated inside the semiconductor layer6′, holes are gathered at the lower electrode11′ and are accumulated at a charge storage capacitor5′ which is electrically connected to the lower electrode11′. On the other hand, if a negative bias is applied to the upper electrode7′, then among the charges generated inside the semiconductor layer6′, electrons are gathered at the lower electrode11′ and are accumulated at the charge storage capacitor5′. Charge amounts that are generated in the semiconductor layer6′ vary in accordance with irradiated X-ray quantities. Therefore, charges corresponding to image information carried by the X-rays are accumulated in the charge storage capacitors of the respective pixels. Subsequently, signals turning the TFT switches4′ ON are sequentially applied through the scan lines101′ illustrated inFIG. 8. Then the charges accumulated in the charge storage capacitors5′ are fed out through the signal lines3′.

However, in this kind of electromagnetic wave detecting element10′, a portion of the charges generated in the semiconductor layer6′ are trapped in the semiconductor layer6′. Consequently, a portion of the generated charges may not be collected by the lower electrode11′, and a residual image may be formed.

FIG. 10schematically illustrates a state in which the charges generated in the semiconductor layer6′ at a region of the scan line101′ of this kind of electromagnetic wave detecting element10′ are being collected. Note thatFIG. 10shows a cross-sectional view along line B-B ofFIG. 8A.

As shown inFIG. 10, the generated charges are collected by the lower electrodes11′. However, a portion of the generated charges are trapped at the semiconductor layer6′.

In Japanese patent application laid-open (JP-A) No. 2004-33659, a technology that suppresses the creation of a residual image is described. In this technology, a light generator (a backlight device) is disposed at a rear face of the electromagnetic wave detecting element10′, and light is illuminated onto the electromagnetic wave detecting element10′ by the light generator.

When the technology recited in JP-A No. 2004-33659 is employed and light is illuminated onto the electromagnetic wave detecting element10′, there is a consistent effect of suppression of the creation of residual images which are caused by trapping of charges.

However, further suppression of residual images has been called for in recent years. Due thereto, suppression of the trapping of charges in the semiconductor layer6′ is essential for this.

SUMMARY OF THE INVENTION

The present invention is to provide an electromagnetic wave detecting element that can suppress trapping of charges in a semiconductor layer.

A first aspect of the present invention is an electromagnetic wave detecting element including: an insulative substrate; a plurality of scan lines and a plurality of signal lines that are disposed on the insulative substrate, to intersect one another, in different wiring layers with a first insulation film interposed; a plurality of collection electrodes, that collects generated charges, disposed respectively individually in correspondence with intersection portions of the plurality of scan lines and the plurality of signal lines, on a second insulation film layered above the plurality of scan lines and the plurality of signal lines; and a semiconductor layer, that generates charges when irradiated with predetermined electromagnetic waves, uniformly formed on a layer above the plurality of collection electrodes, wherein the plurality of collection electrodes are provided to each cover at least a portion in a longitudinal direction and the entire region in a lateral direction of at least one of the scan line or signal line that are adjacent to the respective collection electrode.

In the first aspect of the present invention, the plural scan lines and the plural signal lines are disposed on the insulative substrate, orthogonally to one another, in the different wiring layers with the first insulation film therebetween. The plural collection electrodes that collect generated charges are disposed respectively individually in correspondence with the intersection portions of the plural scan lines and the plural signal lines, in a layer above the plural scan lines and plural signal lines, with the second insulation layer therebetween. The semiconductor layer that generates charges when the predetermined electromagnetic waves are irradiated is uniformly formed in a layer above the plural collection electrodes.

In the present invention, the plural electrodes are each disposed so as to cover at a least a portion of the longitudinal direction and the entire region of the lateral direction of at least one line of the scan line and signal line that are adjacent thereto.

According to the first aspect, the plural electrodes that collect the charges generated in the semiconductor layer are each disposed so as to cover the at least a portion of the longitudinal direction and the entire region of the lateral direction of the at least one of the scan line and the signal line that are adjacent thereto. Thus, according to the first aspect, the collection electrodes are provided at positions at which the scan lines or signal lines are disposed. Due thereto, charges generated in the semiconductor layer at regions of the positions at which the scan lines or signal lines are disposed are collected by the collection electrodes rather than being trapped. Therefore, the present invention may suppress trapping of charges in the semiconductor layer.

A second aspect of the present invention may be, in the aspect described above, the electromagnetic wave detecting element wherein the plurality of collection electrodes are each provided with a portion extended over the second insulation film such that the respective collection electrode covers the at least a portion in the longitudinal direction and the entire region in the lateral direction of the at least one of the scan line and signal line.

A third aspect of the present invention may be, in an aspect described above, the electromagnetic wave detecting element wherein the plurality of collection electrodes are each provided so as to cover the at least a portion in the longitudinal direction and the entire region in the lateral direction of the scan line that is adjacent thereto.

A fourth aspect of the present invention may be, in an aspect described above, the electromagnetic wave detecting element wherein the plurality of scan lines each control extraction to the signal lines of the charges collected at the collection electrodes that are adjacent to the respective scan line at one side in the signal line direction, and the plurality of collection electrodes are superposed with the scan lines that are adjacent thereto at the one side in the signal line direction.

A fifth aspect of the present invention may be, in an aspect described above, the electromagnetic wave detecting element wherein the plurality of collection electrodes are superposed, with the scan lines that are respectively adjacent at the one side in the signal direction, with a predetermined alignment margin.

A sixth aspect of the present invention may be, in an aspect described above, the electromagnetic wave detecting element further including a plurality of thin film transistors that are disposed respectively individually in correspondence with the intersection portions of the plurality of scan lines and the plurality of signal lines, the plurality of the thin film transistors including, gate electrodes of the thin film transistors being electrically connected with the scan lines, source electrodes being electrically connected with either one of the signal lines or the collection electrodes, and drain electrodes being electrically connected with the other of the signal lines or the collection electrodes, wherein the plurality of collection electrodes are disposed so as to cover the thin film transistors to which the collection electrodes are electrically connected.

Herein, the meaning of the term “electromagnetic waves” is to include electromagnetic waves that are detected and cause charges to be generated at the above-mentioned semiconductor layer. For example, in the case of an indirect-conversion-type electromagnetic wave detecting element, light generated by a scintillator corresponds to the term electromagnetic waves. However, in the case of an indirect conversion type, the present invention may be applied only to a configuration in which the semiconductor layer is formed above the collection electrodes uniformly.

Thus, according to the present invention, charges that are generated in the semiconductor layer at regions of positions at which the scan lines or signal lines are disposed are collected by the collection electrodes rather than being trapped. Therefore, the present invention may suppress trapping of charges in the semiconductor layer.

DETAILED DESCRIPTION OF THE INVENTION

Herebelow, exemplary embodiments of the present invention will be described while referring to the attached drawings. Note that, hereinafter, a case will be described in which the present invention is applied to a radiation image photography device100that employs a direct-conversion-type electromagnetic wave detecting element10.

FIG. 1illustrates overall structure of the radiation image photography device100relating to the first exemplary embodiment.

As shown inFIG. 1, the radiation image photography device100relating to the present exemplary embodiment includes the electromagnetic wave detecting element10.

The electromagnetic wave detecting element10is provided with an upper electrode, a semiconductor layer and lower electrodes, which will be described later. A large number of pixels that are structured to include sensor portions103and TFT switches4are provided in a two-dimensional form at the electromagnetic wave detecting element10. The sensor portion103receives irradiated radiation and generates charges. The charge storage capacitor5accumulates the charges generated by the sensor portion103. The TFT switch4reads out the charges that have been accumulated in the charge storage capacitor5. One electrode of the charge storage capacitor5is grounded via a storage capacitor line102(seeFIG. 2), which will be described later, and is set to ground level. InFIG. 1, the one electrode of each charge storage capacitor5is connected to ground individually.

In the electromagnetic wave detecting element10, plural scan lines101and plural signal lines3are provided so as to intersect one another. The plural scan lines101turn the TFT switches4ON and OFF. The plural signal lines3read out the charges accumulated in the charge storage capacitors5.

At each signal line3, any of the TFT switches4connected to the signal line3is turned ON. Due thereto, an electronic signal corresponding to electronic charge accumulated in the charge storage capacitor5flows into the signal line3. A signal sensing circuit105, which senses the electronic signals flowing out through the signal lines3, is connected to the signal lines3. A scan signal control device104is connected to the scan lines101. The scan signal control device104outputs control signals for turning the TFT switches4on the scan lines101ON and OFF.

The signal sensing circuit105incorporates amplification circuits that amplify the electronic signals inputted from each signal line3. In the signal sensing circuit105, the electronic signals inputted by the signal lines3are amplified by the amplification circuits and sensed. Due thereto, the signal sensing circuit105senses the charge amounts accumulated in the charge storage capacitors5, to serve as information of pixels constituting an image.

A signal processing device106, which applies predetermined processing to the electronic signals sensed at the signal sensing circuit105, is connected to the signal sensing circuit105and the scan signal control device104. The signal processing device106also outputs control signals representing timings of signal sensing to the signal sensing circuit105, and outputs control signals representing timings of output of scan signals to the scan signal control device104.

Next, the electromagnetic wave detecting element10relating to the present exemplary embodiment will be described in more detail with reference toFIG. 2andFIG. 3.FIG. 2shows a plan view illustrating structure of a single pixel unit of the electromagnetic wave detecting element10, relating to the present exemplary embodiment.FIG. 3shows a cross sectional view along line A-A ofFIG. 2.

As shown inFIG. 3, in the electromagnetic wave detecting element10, the scan line101, a storage capacitor lower electrode14, a gate electrode2and the storage capacitor line102(seeFIG. 2) are formed on an insulative substrate1, which is formed of non-alkaline glass or the like. The gate electrode2is connected to the scan line101, and the storage capacitor lower electrode14is connected to the storage capacitor line102. A wiring layer, in which the scan line101, the storage capacitor lower electrode14and the storage capacitor line102are formed (hereinafter, this wiring layer is referred to as the first signal wiring layer), is formed by using Al or Cu, or a layered film formed mainly of Al or Cu. However, the formation of the wiring layer is not limited to these.

An insulation film15is formed on substantially the entire surface of the region on the first signal wiring layer. A portion thereof that is disposed over the gate electrode2is utilized as a gate insulation film of the TFT switch4. The insulation film15is formed of, for example, SiNxor the like, and is formed by, for example, CVD (chemical vapor deposition) film formation.

A semiconductor active layer8is formed on the insulation film15at a position corresponding with the gate electrode2. The semiconductor active layer8is the channel of the TFT switch4and is formed of, for example, an amorphous silicon film.

A source electrode9and a drain electrode13are formed over the layers described above. The signal line3is formed together with the source electrode9and the drain electrode13in a wiring layer in which the source electrode9and the drain electrode13are formed. At a position on the insulation film15that corresponds with the storage capacitor lower electrode14, a storage capacitor upper electrode18is formed. The source electrode9is connected to the signal line3, and the drain electrode13is connected to the storage capacitor upper electrode18(seeFIG. 2). Note that, the source electrode9and drain electrode13of the TFT switch4may be reversed in accordance with the polarity of charges to be accumulated at the storage capacitor line102. The wiring layer in which the source electrode9, the drain electrode13, the storage capacitor upper electrode18and the signal line3are formed (hereinafter, this wiring layer is referred to as the second signal wiring layer), is formed by using Al or Cu, or a layered film formed mainly of Al or Cu. However, the formation of the wiring layer is not limited to these.

A contact layer (not shown) is formed between the source electrode9and drain electrode13and the semiconductor active layer8. The contract layer is formed as an impurity-doped semiconductor layer, of impurity-doped amorphous silicon or the like. In the electromagnetic wave detecting element10relating to the present exemplary embodiment, the TFT switch4is configured by the gate electrode2, the insulation film15, the source electrode9, the drain electrode13and a semiconductor layer6. Further, the charge storage capacitor5is configured by the storage capacitor lower electrode14, the gate insulation film15and the storage capacitor upper electrode18, or the like.

An interlayer insulation film12is formed to cover the second signal wiring layer, over substantially the entire surface of the region at which the pixel is formed on the insulative substrate1(over substantially the entire region). The interlayer insulation film12is formed of an organic material such as acrylic resin or the like that has photosensitivity, with a film thickness of 1-4 μm and a relative permittivity of 2-4. In the electromagnetic wave detecting element10relating to the present exemplary embodiment, a capacitance between metals disposed in a layer above and the layer below the interlayer insulation film12is kept low by the interlayer insulation film12. Further, generally, such a material also functions as a flattening film, and also has the effect of flattening the steps of the lower layer. Because the shapes of semiconductor layer6that are disposed at the upper layer are flattened thereby, a decrease in the absorption efficiency due to unevenness of the semiconductor layer6, and an increase in leak current can be suppressed. Further, a contact hole16is formed in the interlayer insulation film12at a position opposing the storage capacitor upper electrode18.

In each pixel, a lower electrode11of the sensor portion103is formed on the interlayer insulating film12, so as to cover the pixel region while filling-in the contact hole16. The lower electrode11is formed of an ITO (indium tin oxide) film, and is connected with the storage capacitor upper electrode18.

In the present exemplary embodiment, the lower electrode11is configured so as to extend in the signal line direction on the interlayer insulation film12, and so as to cover the TFT switch4to which the lower electrode11is electrically connected. Furthermore, the lower electrode11is provided so as to cover at least a portion of a longitudinal direction and the entire region of a lateral direction of the scan line101to which the lower electrode11is electrically connected via the TFT switch4, with a predetermined alignment margin (for example, 2-5 μm). With this structure, the lower electrode11completely covers a portion of positions at which the scan line101is disposed. Moreover, the lower electrode11is disposed such that respective gaps19between the lower electrodes11that are adjacent to one another in the signal line direction are away from the positions at which the scan lines101are disposed.

The semiconductor layer6is uniformly formed on the lower electrode11over substantially the entire surface of a pixel region in which pixels are provided on the insulative substrate1(a detection target region). Electromagnetic waves such as X-rays or the like are irradiated at the semiconductor layer6. Accordingly, the semiconductor layer6generates charges (electrons and holes) thereinside. That is, the semiconductor layer6features conductivity for electromagnetic waves and converts image information in the X-rays to charge information. The semiconductor layer6is formed of, for example, a-Se (amorphous selenium), of which selenium is the principal component. Here, the meaning of the term principal component is the inclusion of a content of at least 50%.

An upper electrode7is formed on the semiconductor layer6. A bias power source30, to be described later (seeFIG. 4), is connected to the upper electrode7. A bias voltage is provided from the bias power source30.

Hereafter, principles of operation of the radiation image photography device100relating to the present implement will be described.

In a state in which a bias voltage is applied between the upper electrode7and the storage capacitor lower electrode14, when X-rays are irradiated at the semiconductor layer6, charges (electron-hole pairs) are generated inside the semiconductor layer6.

The semiconductor layer6and the charge storage capacitor5are configured to be electrically connected in series. Therefore, electrons generated in the semiconductor layer6migrate to a positive (plus) electrode side and holes migrate to a negative (minus) electrode side. During image sensing, a negative bias is applied to the gate electrode2of the TFT switch4, keeping the TFT switch4turned OFF. Consequently, the electrons that are generated in the semiconductor layer6are collected by the lower electrode11and accumulated at the charge storage capacitor5. However, a portion of the charges that are generated are trapped in the semiconductor layer6.

The inventors of the present invention have discovered that many charges are trapped at positions of the semiconductor layer6at which the scan line101or the signal line3is disposed. A cause of this is that, because the scan line101and the signal line3are fixed at particular potentials during image sensing, the electric field that is supposed to be applied between the upper electrode7and the lower electrode11(the collection electrode) is also applied between the upper electrode7and the scan line101or the signal line3. Thus, rather than approaching the lower electrode11, the charges generated in the semiconductor layer6are likely to be trapped, by lines of electric force that are formed from the upper electrode7to the scan line101or the signal line3, in the vicinity of a boundary between the interlayer insulation film12and the semiconductor layer6that is disposed in the layer above the scan line101or signal line3.

Accordingly, in the present exemplary embodiment, the lower electrode11is provided to extend in the signal line direction over the interlayer insulation film12, and is provided such that at least a portion in the longitudinal direction and the entire region in the lateral direction of the scan line101are covered by the lower electrode11. Furthermore, the lower electrode11is provided such that the gaps19between the lower electrodes11that are adjacent to one another in the signal line direction avoid the positions at which the scan lines101are disposed.

FIG. 4schematically illustrates a state in which charges generated are being collected in the semiconductor layer6at the scan line101region of the electromagnetic wave detecting element10relating to the present exemplary embodiment.FIG. 4is a cross sectional view along line B-B ofFIG. 2.

As shown inFIG. 4, because the lower electrode11is superposed with the scan line101, the lower electrode11is provided at positions at which the scan line101is disposed and collects charges of the semiconductor layer6. As a result, trapping of charges in the semiconductor layer is suppressed. This is thought to be because there is no wiring that is fixed at a particular potential in the region of the gap19, consequently lines of electric force in the region of the gap19are curved towards the lower electrodes, and thus trapped charges are reduced.

Now, many charges are trapped at positions at which the signal line3is disposed. Accordingly, the lower electrode11may be disposed at positions at which the signal line3is disposed, by the lower electrode11being provided on the interlayer insulation film12to extend in the scan line direction and being superposed with the signal line3. However, if the signal line3and the lower electrode11are superposed, the electrostatic capacitance of the signal line3will be larger, and noise produced at the signal line3will be greater. Therefore, in the present exemplary embodiment the lower electrode11is superposed only with the scan line101.

Moreover, in the present exemplary embodiment, the lower electrode11is superposed with the scan line101with the predetermined alignment margin. Therefore, the lower electrode11is completely superposed with the scan line101. With this structure, variations in the electrostatic capacitance of the scan line101are suppressed by the lower electrode11. That is, the electrostatic capacitance of the scan line101varies with the size of a region at which the lower electrode11is superposed. For example, if there was no alignment margin, shifting of the positions of the lower electrodes11in the signal line direction would occur due to fabrication errors, alignment offsets and the like during fabrication of the electromagnetic wave detecting element10. When a shift occurred, the lower electrode11would not cover the entire region of the scan line101but be superposed with a portion of the scan line101, and the electrostatic capacitance would change greatly in accordance with the degree of this superposition. Therefore, in the present exemplary embodiment, the lower electrode11is superposed with the scan line101with the predetermined alignment margin.

Furthermore, in the present exemplary embodiment, the lower electrode11is provided so as to cover the TFT switch4that is electrically connected to the lower electrode11. With this structure, if a large quantity of charge is generated in the semiconductor layer6, collected by the lower electrode11and accumulated in the charge storage capacitor5, the potential of the lower electrode11rises and the TFT switch4turns ON, and the charge flows out into the signal line3. Thus, the above-described structure functions as a protection circuit that protects the sensor portion103, the TFT switch4and the like from excessive charges.

During image reading, ON signals (+10 to 20 V) are sequentially applied through the scan lines101to the gate electrodes2of the TFT switches4. Thus, the TFT switches4are sequentially turned ON, and electronic signals corresponding to the charge amounts accumulated in the charge storage capacitors5flow out into the signal lines3. The signal sensing circuit105senses the charge amounts accumulated at the charge storage capacitors5of the sensor portions103as information of the respective pixels. Thus, the electromagnetic wave detecting element10may provide image information representing an image represented by the irradiated X-rays.

As described above, according to the present exemplary embodiment, the plural lower electrodes11that collect charges generated in the semiconductor layer6are provided so as to cover at least a portion in the longitudinal direction and entire region of the lateral direction of the respective adjacent scan lines101. The lower electrodes11are provided at positions at which the scan lines101are disposed. Due thereto, the present exemplary embodiment may suppress trapping of charges in the semiconductor layer6.

Structure of the radiation image photography device100relating to a second exemplary embodiment is the same as in the first exemplary embodiment described above (seeFIG. 1), therefore detailed descriptions thereof will be omitted.

FIG. 5shows a plan view illustrating the constitution of a single pixel unit of the electromagnetic wave detecting element10relating to the present exemplary embodiment. Portions that are the same as in the first exemplary embodiment are assigned the same reference numerals, and therefore detailed descriptions thereof will be omitted.

As shown inFIG. 5, each scan line101is electrically connected to the TFT switch4that is adjacent at one side thereof in the signal line direction (at the upper side inFIG. 5). The scan line101controls extraction to the signal line3of charge collected at the lower electrode11that is adjacent at the one side thereof in the signal line direction.

In the present exemplary embodiment, a portion of the lower electrode11is provided extending further to the one side in the signal line direction and is superposed with the scan line101that is adjacent to the one side thereof, with a predetermined alignment margin. Another portion of the lower electrode11is provided extending to the other side in the signal line direction, and is provided so as to cover the TFT switch4to which the lower electrode11is electrically connected. Superposing the entire region of connection between the TFT switch4and the scan line101with the lower electrode11, with the predetermined alignment margin, is difficult in regard to arrangement of the lower electrode11. Therefore, in the present exemplary embodiment, the gap19between the lower electrodes11that are adjacent to one another in the signal line direction is provided so as to avoid positions at which the scan line101is disposed, except at the region of connection between the TFT switch4and the scan line101.

FIG. 6schematically illustrates a state in which charges generated in the semiconductor layer6are being collected at the scan line101region of the electromagnetic wave detecting element10relating to the present exemplary embodiment. Note that,FIG. 6is a cross sectional view along line B-B ofFIG. 5.

As shown inFIG. 5, the portion of the lower electrode11provided extending to the one side in the signal line direction and the lower electrode11is superposed with the adjacent scan line101. Due thereto, because the lower electrode11is provided at positions at which the scan line101is disposed and collects charges in the semiconductor layer6, trapping of charges in the semiconductor layer6may be suppressed.

If the lower electrode11is superposed with the scan line101to which the lower electrode11is electrically connected, as in the first exemplary embodiment, switching noise that occurs when the TFT switch4is switching would be greater. That is, if the lower electrode11is superposed with the scan line101to which the lower electrode11is electrically connected, at a time of switching of the TFT switch4, the potential of the lower electrode11is changed by coupling because of a change in voltage applied to the scan line101. This change in potential is a cause of noise. In contrast, if the lower electrode11is superposed with the scan line101that is adjacent to the one side in the signal line direction, as in the present exemplary embodiment, the potential of the scan line101coupled with the lower electrode11does not change at a time of switching of the TFT switch4of a subject pixel (i.e., at a time of reading). Therefore, the present exemplary embodiment may suppress noise.

As described above, according to the present exemplary embodiment, a portion of the lower electrode11is extended, and a portion of the gap19between the respective adjacent lower electrodes11is provided so as to avoid positions at which the scan line101is disposed. Further, because the lower electrode11is provided at a portion of positions at which the scan line101is disposed, the present exemplary embodiment may suppress trapping of charge in the semiconductor layer6.

In a related art radiation image photography device, 10 seconds after irradiation of 600 mR, a residual image of 0.2 mR is formed. By contrast, according to experimental results from the inventors, with the present constitution, the residual image can be reduced to 0.04 mR.

Now, for the exemplary embodiments described above, cases have been described in which the lower electrode11is superposed with the scan line101by the lower electrode11being provided extending in the signal line direction. However, the present invention is not to be limited thus. For example, as shown inFIG. 11, the lower electrode11may be provided to be shifted in the signal line direction and thus be superposed with the adjacent scan line101while covering the TFT switch4to which the lower electrode11is electrically connected. As a further example, as shown inFIG. 7, the lower electrode11may be shifted further in the signal line direction and thus the lower electrode11may be superposed with the TFT switch4of the adjacent pixel and with the adjacent scan line101.

Further, for the above exemplary embodiments, cases have been described in which the present invention is applied to the radiation image photography device100that detects an image by detecting X-rays, which serve as the electromagnetic waves that are the detection object. However, the present invention is not to be limited thus. For example, the electromagnetic waves that are the detection object may be any of visible light, ultraviolet light, infrared light and so forth.

Further, for the above exemplary embodiments, cases have been described in which the present invention is applied to the radiation image photography device100employing the direct conversion-type electromagnetic wave detecting element10that directly converts radiation to charges in the semiconductor layer and accumulates the same. However, the present invention is not to be limited thus. For example, the present invention may be applied to a radiation image photography device employing an indirect conversion-type electromagnetic wave detecting element that temporarily converts radiation to light with a scintillator, converts the converted light to charge in a semiconductor layer and accumulates the same.

Furthermore, the constitution of the radiation image photography device100described in the above exemplary embodiments (seeFIG. 1) and the constitutions of the electromagnetic wave detecting element10(FIG. 2toFIG. 7) are examples. Suitable modifications are possible within a scope not departing from the spirit of the present invention.