Photoelectric converter, its driving method, and system including the photoelectric converter

Abstract

A photoelectric converter of a high signal-to-noise ratio, low cost, high productivity and stable characteristics and a system including the above photoelectric converter. The photoelectric converter includes a photoelectric converting portion in which a first electrode layer, an insulating layer for inhibiting carriers from transferring, a photoelectric converting semiconductor layer of a non-single-crystal type, an injection blocking layer for inhibiting a first type of carriers from being injected into the semiconductor layer and a second electrode layer are laminated in this order on an insulating substrate.

1. A system having a photoelectric converter comprising:
 a plurality of photoelectric converting elements formed on a substrate, each of the photoelectric converting elements including a first electrode layer and a second electrode layer, an insulating layer formed between the first and second electrode layers for inhibiting a first type of carriers from passing through the layer, a semiconductor layer, and an injection blocking layer for inhibiting said first type of carriers from being injected into the semiconductor layer;    a switch elements for applying an electric field to each layer of said photoelectric converting section in a direction so that said first type of carriers are introduced from said semiconductor layer to said second electrode layer in a refresh mode or in a direction so that said first type of carriers generated by light incident on said semiconductor layer remain in said semiconductor layer and said second type of carriers are introduced to said second electrode layer in a photoelectric conversion mode; and    a signal processing means for processing signals output from the photoelectric converting elements.    
     
     
       2. A system according to  claim 1 , further comprising a record means for recording signals output from said signal processing means. 
     
     
       3. A system according to  claim 1 , further comprising a display means for displaying signals output from said signal processing means. 
     
     
       4. A system according to  claim 1 , further comprising a transmission means for transmitting signals output from said signal processing means. 
     
     
       5. A system according to  claim 1 , wherein said photoelectric converter has a phosphor. 
     
     
       6. A system according to  claim 1 , further comprising a light source for emitting light to generate optical information input to said photoelectric converter. 
     
     
       7. A system according to  claim 6 , wherein said light source emits X-rays. 
     
     
       8. A method of driving a photoelectric converting element formed on a substrate, the photoelectric converting element including a first electrode layer; an insulating layer for inhibiting both types of carriers, a first type of carriers and a second type of carriers whose positive or negative characteristics are opposite to those of the first type of carriers, from passing through the layer; a semiconductor layer including the first and second types of carriers; an injection blocking layer for inhibiting the first type of said carriers from being injected into the semiconductor layer; and a second electrode layer arranged adjacent to said injection blocking layer,
 the driving method having a refresh and a photoelectric conversion mode, wherein an electric field is applied so that the first type of said carriers are brought from said semiconductor layer into said second electrode layer in the refresh mode, and    while an electric field is applied so that the first type of said carriers generated by light incident in said semiconductor layer remain in said semiconductor layer and the second type of said carriers are introduced into said second electrode in the photoelectric conversion mode, and, under an influence of an electric field having the same direction as in the photoelectric conversion mode, the first type of said carriers stored in said semiconductor layer are detected.    
     
     
       9. A method according to  claim 8 , further comprising a capacitive storing element wherein integral values depending upon said carriers are stored and read out. 
     
     
       10. A method according to  claim 8 , further comprising a plurality of said photoelectric converting sections wherein the plurality of said photoelectric converting sections are electrically connected in each block and, when one of the blocks is in the photoelectric conversion mode, at least one of the other blocks is turned to the refresh mode. 
     
     
       11. A method according to  claim 8 , wherein an electric field is applied to said photoelectric converting elements in said refresh mode in accordance with a condition represented by (V rG ·q<V D ·q−V FB ·q), where the product (V rG ·q) of a voltage (V rG ) of said first electrode layer in said photoelectric converting section and an electric charge (q) of said first type of carriers becomes smaller than the product (V D ·q−V FB ·q) of a voltage (V D −V FB ), the voltage subtracting a threshold voltage (V FB ) from a voltage (V D ) of said second electrode layer, and the electric charge (q) of said first type of carriers. 
     
     
       12. A method according to  claim 9 , wherein said capacitive element has two electrode layers, an insulating layer held between the electrode layers and a semiconductor layer to be operated in the accumulation state. 
     
     
       13. A photoelectric converter having a photoelectric converting section provided on a substrate having a surface which is at least insulative, and first and second integrated circuit element groups provided outside of said photoelectric converting section, wherein
 said photoelectric converting section has plural combinations of a photoelectric converting element and a thin film transistor arranged correspondingly to said photoelectric converting element, one electrode of said photoelectric converting element is connected to a line capable of being set at a predetermined voltage, the other electrode of said photoelectric converting element is connected to one of the source and drain electrodes of said thin film transistor, a gate electrode of said thin film transistor is connected to said first integrated circuit element group arranged outside of said photoelectric converting section through a driving line provided commonly to said plural combinations of a photoelectric converting element and a thin film transistor and said first and second integrated circuit element groups for supplying to said gate electrode a signal for driving said thin film transistor, and the other of the source and drain electrodes different from the one of the source and drain electrodes of said thin film transistor are connected to the second integrated circuit element group through an output line common to a group of said plural combinations of a photoelectric converting element and a thin film transistor and arranged in a direction crossing said driving line;    said photoelectric converting element has first and second electrode layers on said substrate, and has, between said first and second electrode layers, an insulating layer for blocking passage of a hole and an electron therethrough, a semiconductor layer, and a carrier blocking layer for blocking passage of one of the hole and the electron; and    said thin film transistor has, on said substrate, a gate electrode, and source and drain electrodes arranged in spaced relation, and has between said gate electrode and said source and drain electrodes, an insulating layer to be a gate insulating film, a semiconductor layer and an ohmic contact layer, said ohmic contact layer is arranged correspondingly to said source and drain electrodes, and said ohmic contact layer and said source and drain electrodes are provided at one side surface of said semiconductor layer.    
     
     
       14. A photoelectric converter according to  claim 13 , wherein said first electrode layer of said photoelectric converting element, said gate electrode of said thin film transistor, said second electrode layer of said photoelectric converting element, said source and drain electrodes of said thin film transistor, said insulating layer on said photoelectric converting element, said gate insulating film of said thin film transistor, said semiconductor layer of said photoelectric converting element, said semiconductor layer of said thin film transistor, said carrier blocking layer of said photoelectric converting element, and said ohmic contact layer of said thin film transistor are respectively produced from the same material, and have respectively the same thickness. 
     
     
       15. A photoelectric converter according to  claim 13 , wherein said first and second integrated circuit element groups are respectively arranged at a periphery of said photoelectric converting section. 
     
     
       16. A photoelectric converter according to  claim 13 , wherein said photoelectric converting section is quadrilateral, and said first and second integrated circuit element groups are arranged separately along sides of the quadrilateral. 
     
     
       17. A photoelectric converter having a photoelectric converting section provided on a substrate having a surface which is at least insulative, wherein said photoelectric converting section has in matrix arrangement plural combinations of a photoelectric converting element and a thin film transistor arranged correspondingly to said photoelectric converting element, one electrode of said photoelectric converting element is connected to a line capable of being set at a predetermined voltage, the other electrode of said photoelectric converting element is connected to one of the source and drain electrodes of said thin film transistor, the other of the source and drain electrodes of said thin film transistor are connected to an output line common to a group of said plural combinations of a photoelectric converting element and a thin film transistor for outputting a signal derived by a photoelectric conversion of said photoelectric conversion elements of the group, and a gate electrode of said thin film transistor is connected to a driving line common to a group of said plural combinations of a photoelectric converting element and a thin film transistor for supplying said gate electrode with a signal for driving said thin film transistors of this group in a direction crossing the output line for outputting the signal, and
 said photoelectric converter further comprises a passivation film provided on a group of said photoelectric conversion elements and thin film transistors, and a fluorescent body provided on said passivation film.    
     
     
       18. A photoelectric converter according to  claim 17 , wherein said photoelectric converting element has first and second electrode layers on said substrate, an insulating layer between said first and second electrode layers for inhibiting a passage of a hole and an electron therethrough, a semiconductor layer, and a blocking layer for blocking a passage therethrough of one of the hole and the electron, in this order. 
     
     
       19. A photoelectric converter according to  claim 18 , wherein said thin film transistor has, on said substrate, a gate electrode, separately arranged source and drain electrodes, an insulating layer to be a gate insulating film between said gate electrode and said source and, a semiconductor layer and an ohmic contact layer, wherein said ohmic contact layer is provided correspondingly to the source and drain electrodes, and said ohmic contact layer and said source and drain electrodes are provided at one side surface of said semiconductor layer. 
     
     
       20. A method for driving a photoelectric converting section which comprises a first electrode layer; an insulating layer for preventing carriers of both of two types from passing through said insulating layer, the two types of carriers being a first type of carrier and a second type of carrier whose positive or negative polarity is opposite that of the first type of carrier; a semiconductor layer; an injection blocking layer for preventing said first type of carrier from being injected into said semiconductor layer; and a second electrode layer disposed in contact with said injection blocking layer, said method comprising:
 a refreshment mode for applying an electric field for guiding said first type of carrier from said semiconductor layer toward said second electrode layer; and    a photoelectric converting mode for applying an electric field for remaining said first type of carrier generated by incident light in said semiconductor layer and for introducing said second type of carrier from said semiconductor layer into said second electrode layer,    wherein, according to the electric field in the direction in said photoelectric converting mode, a charge corresponding to a carrier stored in said semiconductor layer in the photoelectric converting mode is detected.    
     
     
       21. A method according to  claim 20 , further comprising a storage capacitor element, and wherein a process for storing the carrier in said storage capacitor element for reading is provided. 
     
     
       22. A method according to  claim 20 , wherein a plurality of photoelectric converting sections are provided, and are connected within a respective block that includes a respective group of the photoelectric converting sections, and, when a selected block is in the photoelectric converting mode, at least one other block is in the refreshment mode. 
     
     
       23. A method according to  claim 20 , wherein the electric field applied in the refreshment mode is set to meet a condition that a product (VrG×q) of a voltage (VrG) of the first electrode layer of said photoelectric converting section and a charge (q) of the first type of carrier is not greater than a product ((VD−VFB)×q) of a voltage (VD−VFB) obtained by subtracting a threshold voltage (VFB) from a voltage (VD) of said second electrode layer and the charge (q) of the first type of carrier. 
     
     
       24. A method according to  claim 21 , wherein said storage capacitor element comprises two electrode layers and an insulating layer sandwiched between said electrode layers. 
     
     
       25. A method according to  claim 21 , wherein the charge corresponding to the stored carrier has a quantity of a charge flowing at the application of the electric field in the same direction as in the refreshment mode. 
     
     
       26. A method according to  claim 21 , wherein a charge quantity corresponding to the stored carrier is a charge quantity flowing in the photoelectric converting mode. 
     
     
       27. A method according to  claim 21 , further comprising a step of subtracting from the charge corresponding to the stored carrier a charge corresponding to the stored carrier in a case of non-incident light at the photoelectric converting mode. 
     
     
       28. A photoelectric converter according to  claim 13 , further comprising a fluorescent substance on said photoelectric converting element. 
     
     
       29. A photoelectric converter according to  claim 13 , wherein said photoelectric converting element and said thin film transistor have thereon a passivation film, on which a fluorescent substance is provided. 
     
     
       30. An X- ray detection apparatus comprising:      a base plate;        a sensor substrate disposed over the base plate, wherein a plurality of pixels, each including a photoelectric conversion element, are arranged over an insulating substrate;        a phosphor for converting X - ray into light disposed over the sensor substrate;        a processing circuit disposed such that the base plate is positioned in between the processing circuit and the sensor substrate, for processing a signal from at least one of the pixels;        a plate disposed between the sensor substrate and the processing circuit, for protecting the processing circuit from the X - ray; and        a case for holding the base plate, the sensor substrate, the phosphor, the processing circuit and the plate, wherein at least a part of the case on an opposite side of the phosphor is formed from carbon fiber.      
     
     
       31. The X- ray detection apparatus according to    claim 30   , wherein the processing circuit is disposed over a circuit board, and the processing circuit includes an A/D converter and a memory.    
     
     
       32. The X- ray detection apparatus according to    claim 30   , wherein the plate is disposed between the base plate and the processing circuit, and is formed from a lead plate.    
     
     
       33. The X- ray detection apparatus according to    claim 30   , wherein the pixels each further include a switching element connected to the photoelectric conversion element.    
     
     
       34. The X- ray detection apparatus according to    claim 33   , wherein the switching element is a transistor disposed over the insulating substrate.    
     
     
       35. A X- ray detection system comprising:      the X - ray detection apparatus according to    claim 30   ;        a signal processing unit for processing a signal from the X - ray detection apparatus;        a recording unit for recording a signal from the signal processing unit;        a display unit for displaying the signal from the signal processing unit;        a transmitting unit for transmitting the signal from the signal processing unit; and        an X - ray source for generating X - ray.