Photoconductor-on-active-pixel (POAP) sensor utilizing equal-potential pixel electrodes
First Claim
1. An active pixel sensor for producing images from electron-hole producing radiation comprising:
- A) a solid state radiation detection unit comprising;
1) a crystalline semiconductor substrate;
2) a plurality of Complementary Metal Oxide Semiconductor pixel circuits incorporated into said substrate to form an array of pixel circuits, wherein each of said array of pixel circuits comprises;
a) a charge collecting pixel electrode;
b) a charge sensing node;
c) a gate bias transistor separating said charge collecting pixel electrode and said charge sensing node;
d) a pixel capacitor comprising said charge collecting pixel electrode and said charge sensing node, wherein said pixel capacitor is configured to store charges collected by said charge collecting pixel electrode;
e) a charge measuring circuit comprising at least one transistor, wherein a gate of said at least one transistor is electrically connected to said charge sensing node;
3) a radiation absorbing layer comprised of photoconductive material covering at least a portion of said array of pixel circuits, wherein said photoconductive material is photoconductive on exposure to said electron-hole producing radiation;
4) a surface electrode layer comprised of electrically conducting material and formed on said radiation absorbing layer, wherein said surface electrode layer is at least partially transparent to said electron-hole producing radiation, and connected to a voltage source for establishing an electrical field across said radiation absorbing layer and between said surface electrode layer and each of said array of charge collecting pixel electrodes; and
B) an array measurement circuit for measuring charges collected by each of said array of charge collecting pixel electrodes, and for outputting pixel data indicative of said collected charges, wherein said pixel data comprises information defining an image.
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Abstract
An active pixel sensor is disclosed. In one embodiment, a solid state radiation detection unit may be fabricated using a semiconductor substrate having a plurality of CMOS pixel circuits incorporated into the substrate. Typically, each of an array of pixel circuits includes a charge collecting pixel electrode, a charge sensing node, a gate bias transistor separating the charge collecting pixel electrode and the charge sensing node, and a pixel capacitor to store charges collected by the charge collecting pixel electrode. A charge measuring circuit comprising at least one transistor may also be configured with each pixel circuit. The sensor may further include a radiation absorbing layer comprised of photoconductive material, as well as a surface electrode layer comprised of electrically conducting material. The sensor is typically configured with an array measurement circuit for measuring charges collected by the array of charge collecting pixel electrodes and for pixel data output.
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Citations
76 Claims
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1. An active pixel sensor for producing images from electron-hole producing radiation comprising:
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A) a solid state radiation detection unit comprising;
1) a crystalline semiconductor substrate;
2) a plurality of Complementary Metal Oxide Semiconductor pixel circuits incorporated into said substrate to form an array of pixel circuits, wherein each of said array of pixel circuits comprises;
a) a charge collecting pixel electrode;
b) a charge sensing node;
c) a gate bias transistor separating said charge collecting pixel electrode and said charge sensing node;
d) a pixel capacitor comprising said charge collecting pixel electrode and said charge sensing node, wherein said pixel capacitor is configured to store charges collected by said charge collecting pixel electrode;
e) a charge measuring circuit comprising at least one transistor, wherein a gate of said at least one transistor is electrically connected to said charge sensing node;
3) a radiation absorbing layer comprised of photoconductive material covering at least a portion of said array of pixel circuits, wherein said photoconductive material is photoconductive on exposure to said electron-hole producing radiation;
4) a surface electrode layer comprised of electrically conducting material and formed on said radiation absorbing layer, wherein said surface electrode layer is at least partially transparent to said electron-hole producing radiation, and connected to a voltage source for establishing an electrical field across said radiation absorbing layer and between said surface electrode layer and each of said array of charge collecting pixel electrodes; and
B) an array measurement circuit for measuring charges collected by each of said array of charge collecting pixel electrodes, and for outputting pixel data indicative of said collected charges, wherein said pixel data comprises information defining an image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A method of minimizing pixel crosstalk between pixels in an active pixel sensor array comprising:
A) fabricating a solid state radiation detection unit comprising;
1) providing a crystalline semiconductor substrate;
2) incorporating a plurality of Complementary Metal Oxide Semiconductor pixel circuits into said substrate to form an array of pixel circuits, wherein each of said array of pixel circuits comprises;
a) a charge collecting pixel electrode;
b) a charge sensing node;
c) a gate bias transistor separating said charge collecting pixel electrode and said charge sensing node;
d) a pixel capacitor comprising said charge collecting pixel electrode and said charge sensing node, wherein said pixel capacitor is configured to store charges collected by said charge collecting pixel electrode;
e) a charge measuring circuit comprising at least one transistor, wherein a gate of said at least one transistor is electrically connected to said charge sensing node;
3) covering at least a portion of said array of pixel circuits with a radiation absorbing layer comprising photoconductive material, wherein said photoconductive material is photoconductive on exposure to said electron-hole producing radiation;
4) forming a surface electrode layer comprising electrically conducting material on said radiation absorbing layer, wherein said surface electrode layer is at least partially transparent to said electron-hole producing radiation, and connected to a voltage source for establishing an electrical field across said radiation absorbing layer and between said surface electrode layer and each of said array of charge collecting pixel electrodes;
B) measuring charges collected by each of said array of charge collecting pixel electrodes with an array measurement circuit; and
C) outputting pixel data indicative of said collected charges of said array of charge collecting pixel electrodes, wherein said pixel data comprises information defining an image. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76)
Specification