Dual active layer semiconductor device and method of manufacturing the same

Abstract

Some embodiments include an imaging system. The imaging system includes an active matrix pixel array having a flexible substrate and a pixel. The pixel includes a transistor over the flexible substrate, and the transistor includes multiple active layers having a first active layer and a second active layer over the first active layer. Further, the active matrix pixel array also includes a photodiode over the transistor, and the photodiode includes an N-type layer over the transistor, an I layer over the N-type layer, and a P-type layer over the I layer. Meanwhile, the imaging system also includes a flexible scintillator layer over the active matrix pixel array. Other embodiments of related systems and methods are also disclosed.

What is claimed is: 
     
         1 ) An imaging system comprising:
 an active matrix pixel array comprising a flexible substrate and a pixel, wherein the pixel comprises:
 a transistor over the flexible substrate, the transistor comprising multiple active layers comprising a first active layer and a second active layer over the first active layer; 
 and 
 a photodiode over the transistor, the photodiode comprising:
 an N-type layer over the transistor; 
 an I layer over the N-type layer; and 
 a P-type layer over the I layer; 
 
   and   a flexible scintillator layer over the active matrix pixel array.   
     
     
         2 ) The imaging system of  claim 1  wherein:
 the first active layer comprises at least one first metal oxide and a first conductivity; and 
 the second active layer comprises at least one second metal oxide and a second conductivity less than the first conductivity. 
 
     
     
         3 ) The imaging system of  claim 1  wherein:
 the N-type layer comprises at least one of aluminum, silicon, neodymium, tantalum, molybdenum, chromium, titanium, or tungsten; 
 the N-type layer is greater than or equal to approximately 100 nanometers thick and less than or equal to approximately 200 nanometers thick; 
 the I layer comprises intrinsically doped silicon; 
 the I layer is greater than or equal to approximately 100 nanometers thick and less than or equal to approximately 150 nanometers thick; 
 the P-type layer comprises boron doped silicon; and 
 the P-type layer is greater than or equal to approximately 5 nanometers and less than or equal to approximately 20 nanometers. 
 
     
     
         4 ) The imaging system of  claim 1  wherein:
 the active matrix pixel array comprises a threshold voltage shift greater than or equal to approximately −1 volt and less than or equal to approximately 1 volt. 
 
     
     
         5 ) The imaging system of  claim 1  further comprising:
 a flexible base plate under the active matrix pixel array. 
 
     
     
         6 ) The imaging system of  claim 1  further comprising:
 a gate driver line coupled to the pixel; and 
 a data line coupled to the pixel. 
 
     
     
         7 ) The imaging system of  claim 1  wherein:
 the active matrix pixel array and the flexible scintillator layer comprise a central axis; and 
 the active matrix pixel array and the flexible scintillator layer are configured to be able to flex up to approximately 45 degrees with respect to the central axis. 
 
     
     
         8 ) The imaging system of  claim 1  wherein at least one of:
 the flexible substrate comprises at least one of polyethylene naphthalate, polyethylene terephthalate, polyethersulfone, polyimide, polycarbonate, cyclic olefin copolymer, or liquid crystal polymer; or 
 the flexible scintillator layer comprises gadolinium oxysulfide. 
 
     
     
         9 ) The imaging system of  claim 1  wherein:
 the N-type layer comprises at least one of aluminum, silicon, neodymium, tantalum, molybdenum, chromium, titanium, or tungsten; 
 the N-type layer is greater than or equal to approximately 100 nanometers thick and less than or equal to approximately 200 nanometers thick; 
 the I layer comprises intrinsically doped silicon; 
 the I layer is greater than or equal to approximately 100 nanometers thick and less than or equal to approximately 150 nanometers thick; 
 the P-type layer comprises boron doped silicon; 
 the P-type layer is greater than or equal to approximately 5 nanometers and less than or equal to approximately 20 nanometers; 
 the flexible substrate comprises at least one of polyethylene naphthalate, polyethylene terephthalate, polyethersulfone, polyimide, polycarbonate, cyclic olefin copolymer, or liquid crystal polymer; 
 the flexible scintillator layer comprises gadolinium oxysulfide; and 
 the imaging system further comprises:
 a flexible base plate under the active matrix pixel array; 
 a gate driver line coupled to the pixel; and 
 a data line coupled to the pixel. 
 
 
     
     
         10 ) A method of manufacturing an imaging system, the method comprising:
 providing an active matrix pixel array, wherein providing the active matrix pixel array comprises:
 providing a flexible substrate; and 
 providing a pixel, wherein providing the pixel comprises:
 providing a transistor over the flexible substrate, the transistor comprising multiple active layers comprising a first active layer and a second active layer over the first active layer; and 
 providing a photodiode over the transistor, wherein providing the photodiode comprises:
 providing an N-type layer over the transistor; 
 providing an I layer over the N-type layer; and 
 providing a P-type layer over the I layer; 
 
 
   and   providing a flexible scintillator layer over the active matrix pixel array.   
     
     
         11 ) The method of  claim 10  wherein:
 providing the transistor over the flexible substrate comprises:
 providing at least one first metal oxide over the flexible substrate to form the first active layer, the first active layer comprising a first conductivity; and 
 providing at least one second metal oxide over the first active layer to form the second active layer, the second active layer comprising a second conductivity less than the first conductivity. 
 
 
     
     
         12 ) The method of  claim 10  wherein:
 providing the N-type layer over the transistor comprises providing at least one of aluminum, silicon, neodymium, tantalum, molybdenum, chromium, titanium, or tungsten over the transistor, the N-type layer being greater than or equal to approximately 100 nanometers thick and less than or equal to approximately 200 nanometers thick; 
 providing the I layer over the N-type layer comprises providing intrinsically doped silicon over the N-type layer, the I layer being greater than or equal to approximately 100 nanometers thick and less than or equal to approximately 150 nanometers thick; 
 and 
 providing the P-type layer over the I layer comprises providing boron doped silicon over the I layer, the P-type layer being greater than or equal to approximately 5 nanometers and less than or equal to approximately 20 nanometers. 
 
     
     
         13 ) The method of  claim 10  further comprising:
 providing a flexible base plate under the active matrix pixel array. 
 
     
     
         14 ) The method of  claim 10  further comprising:
 coupling a gate driver line to the pixel; and 
 coupling a data line to the pixel. 
 
     
     
         15 ) The method of  claim 10  wherein:
 providing the active matrix pixel array and providing the flexible scintillator layer comprises configuring the active matrix pixel array and the flexible scintillator layer to be able to flex up to approximately 45 degrees with respect to a central axis of the active matrix pixel array and the flexible scintillator layer. 
 
     
     
         16 ) The method of  claim 10  wherein at least one of:
 the flexible substrate comprises at least one of polyethylene naphthalate, polyethylene terephthalate, polyethersulfone, polyimide, polycarbonate, cyclic olefin copolymer, or liquid crystal polymer; or 
 the flexible scintillator layer comprises gadolinium oxysulfide. 
 
     
     
         17 ) A method of imaging an object with an imaging system, the method comprising:
 positioning the object between an active matrix pixel array of the imaging system and an emitter of electromagnetic radiation, the active matrix pixel array comprising a flexible substrate and a pixel, and the pixel comprising (i) a transistor over the flexible substrate, the transistor comprising multiple active layers comprising a first active layer and a second active layer over the first active layer and (ii) a photodiode over the transistor, the photodiode comprising an N-type layer over the transistor, an I layer over the N-type layer, and a P-type layer over the I layer;   emitting electromagnetic radiation from the emitter of electromagnetic radiation at the active matrix pixel array and the object; and   providing an x-ray representation of the object.   
     
     
         18 ) The method of  claim 17  wherein:
 emitting electromagnetic radiation from the emitter of electromagnetic radiation at the active matrix pixel array and the object comprises receiving part of the electromagnetic radiation at a flexible scintillator layer positioned between the active matrix pixel array and the object; and 
 the method further comprises detecting at the pixel of the active matrix pixel array a photon emitted by the flexible scintillator layer in response to receiving the part of the electromagnetic radiation. 
 
     
     
         19 ) The method of  claim 18  wherein:
 providing the x-ray representation of the object comprises generating the x-ray representation of the object based on the photon detected at the pixel. 
 
     
     
         20 ) The method of  claim 17  further comprising:
 bending the active matrix pixel array such that the active matrix pixel array at least partially surrounds the object.