Pixel structures for optimized x-ray noise performance

摘要

There is provided a pixel (100) for an image sensor, wherein the pixel (100) is based on a doped substrate (110) on which a lightly doped epitaxial layer (120) is provided. A photosensitive structure (130) and an isolating reversely biased well (140) are defined in the epitaxial layer, and the photosensitive structure (130) is encapsulated in the reversely biased well (140). Alternatively, or as a complement, the pixel (100) includes isolating wells extending on respective sides of the photosensitive structure (130) throughout the entire or at least a major part of the epitaxial layer to provide isolation from neighboring pixels of the image sensor.

主权项

1. An x-ray sensor system comprising:
a scintillator configured to absorb x-ray photons and emit photons in the visible range to thus generate a light image; and an image sensor arranged in combination with said scintillator and configured to capture said light image, said image sensor including a pixel based on a doped substrate on which a lightly doped epitaxial layer is provided, an isolating reversely biased well being defined in said epitaxial layer, the reversely biased well being smaller than the epitaxial layer, a photosensitive structure being encapsulated in said reversely biased well, the photosensitive structure being smaller than the reversely biased well, said photosensitive structure being defined by a depletion region in which light from said scintillator is converted to electrical carriers that constitute a signal, said depletion region being contained in its entirety within said reversely biased well to reduce the risk for carriers generated by absorption of x-ray photons outside of the depletion region from contributing noise to the signal.