Abstract:
An imaging device comprises a semiconductor substrate including an array of pixel cells. Each pixel cell comprising an individually addressable pixel circuit for accumulating charge resulting from radiation incident on a pixel detector. The pixel circuit and the pixel detector can either be implemented on a single substrate, or on two substrates bonded together. The charge storage device can be a transistor, for example one of a pair of FET transistors connected as a cascade amplification stage. An imaging plane can be made up of one imaging device or a plurality of imaging devices tiled to form a mosaic. The imaging devices may be configured as a slot for certain applications, the slit or slot being scanned over the imaging plane. Control electronics can include addressing logic for addressing individual pixel circuits for reading accumulated charge from the pixel circuits. Imaging optimization can be achieved by determining maximum and minimum charge values for pixels for display, assigning extreme grey scale or color values to the maximum and minimum charge values and allocating grey scale or color values to an individual pixel according to a sliding scale between the extreme values. Scattered radiation can be detected and discarded by comparing the detected pixel value to a threshold value related to a minimum detected charge value expected for directly incident radiation and discarding detected pixel values less than said threshold value.
Abstract:
A semiconductor radiation imaging device includes an array of pixel cells having an array of pixel detectors which directly generate charge in response to incident radiation and a corresponding array of individually-addressable pixel circuits. Each pixel circuit is associated with a respective pixel detector for accumulating charge directly resulting from radiation incident on the pixel detector and includes threshold circuitry and charge accumulation circuitry. The threshold circuitry is configured to discard radiation hits on the pixel detector outside a predetermined threshold range, and the charge accumulation circuit is configured to accumulate charge directly resulting from a plurality of successive radiation hits on the respective pixel detector within the predetermined threshold range.
Abstract:
A semiconductor high-energy radiation imaging device having an array of pixel cells includes a semiconductor detector substrate and a semiconductor readout substrate. The semiconductor detector substrate includes an array of pixel detector cells, each of which directly generates charge in response to incident high-energy radiation. The semiconductor readout substrate includes an array of individually addressable pixel circuits, each of which is connected to a corresponding pixel detector cell to form a pixel cell. Each pixel circuit includes charge accumulation circuitry for accumulating charge directly resulting from high-energy radiation incident on a corresponding pixel detector cell, readout circuitry for reading the accumulated charge, and reset circuitry for resetting the charge accumulation circuitry. The charge accumulation circuitry has a charge storage capacity sufficient to store at least 1.8 million electrons for accumulating charge directly resulting from a plurality of successive high-energy radiation hits on the corresponding pixel dectector cell prior to readout or resetting of the charge accumulation circuitry.
Abstract:
In a semiconductor imaging device, the distance between the edge of a substrate and an edge-most charge collection contact is made as small as possible, preferably less than 500 &mgr;m and/or less than ⅓ of the substrate thickness. Additionally or alternatively, a passivation layer is placed between the edge-most portion of the contact and the substrate surface and/or a field shaping conductor adjacent to the surface. A field shaping region may also be arranged outside the edge of the substrate and may encircle each detector device, or it may encircle an arrangement of several devices. In such an arrangement, the spacing between adjacent detectors should be less than 500 &mgr;m. A shield may also be used to shield the edge of each detector, or the edge region of the arrangement of several detectors, from incident radiation. Such arrangements can reduce the effect of edge image deterioration caused by strong field non-uniformities at the detector edges.
Abstract:
An imaging device includes one detector substrate with a plurality of readout substrates connected thereto. The detector substrate has a bias contact on a first surface and a number of detector cell contacts on a second surface. The readout substrate includes a plurality of readout circuits. The readout substrates are all mechanically connected to the detector substrate with the readout circuits electrically connected to respective detector cell contacts. To allow for areas of the readout substrates with no readout circuits or gaps between readout circuits, conductive tracks lead from selected detector positions to offset readout circuit position.