Abstract: Pixel structures and a read-out method of pixels are disclosed. The pixel structures and the read-out method improve the image quality of imaging devices or imaging sensors based on such pixels. A pixel comprises in a parallel circuit configuration a radiation sensitive element and an adjustable current source, said current source being adapted for delivering a high current. A 4-transistor pixel structure is also disclosed. A method of obtaining a calibrated read-out signal of a pixel having at least a photosensitive element and a current source comprise a number of steps. A photocurrent generated on the pixel added to a current generated by a current source in parallel with the photosensitive element is read to obtain a first signal. The pixel is also read with the current source off to obtain a second signal. The first signal is subtracted from the second signal, and the resulting signal is amplified to obtain the read-out signal.

Abstract: A semiconductor detector of electromagnetic radiation which utilizes a dual-purpose electrode which extends significantly beyond the edge of a photodiode. This configuration reduces the sensitivity of device performance on small misalignments between manufacturing steps while reducing dark currents, kTC noise, and “ghost” images. The collection-mode potential of the dual-purpose electrode can be adjusted to achieve charge confinement and enhanced collection efficiency, reducing or eliminating the need for an additional pinning layer. Finally, the present invention enhances the fill factor of the photodiode by shielding the photon-created charge carriers formed in the substrate from the potential wells of the surrounding circuitry.

Abstract: A semiconductor device structure is described for reducing radiation induced current flow caused by incident ionizing radiation. The structure comprises a semiconductor substrate; two or more regions of a first conductivity type in the substrate; and a guard ring of a second conductivity type for obstructing radiation induced parasitic current flow between the two or more regions of the first conductivity type. The structure may be used in a pixel, e.g. in a diode or a transistor, for increasing radiation resistance.

Abstract: The present invention provides a particle or electromagnetic radiation sensor structure, comprising a substrate (13) having a major surface and a sensitive layer (16) on the major surface of the substrate (13), the sensitive layer (16) being sensitive to particle or electromagnetic radiation and having a first surface (17) remote from the substrate (13). The sensitive layer (16) has a doping concentration gradient from a higher doping level to a lower doping level, the doping concentration decreasing from the substrate (13) to the first surface (17) of the sensitive layer (16). According to an embodiment, over any distance across the sensitive layer (16) which is half of the thickness of the sensitive layer (16), the ratio between the highest doping level and the lowest doping level is at least a factor 2, preferably at least a factor 3 or more. The present invention also provides a method for obtaining such a sensor structure, as well as arrays comprising such sensor structures.

Abstract: The present invention provides an active pixel including a semiconductor layer (5) having dopants of a first conductivity type, wherein said semiconductor layer (5) comprises a first region (1) and a second region (2) both having dopants of a second conductivity type, said first region (1) and said second region (2) being adapted for collecting charge carriers in said semiconductor layer (5) generated by electromagnetic radiation, said first region (1) having an area and a boundary of this area, said semiconductor layer (5) further comprising a third region (3) having dopants of the first conductivity type at a higher doping level than the semiconductor layer (5), the third region (3) forming a barrier for substantially impeding the diffusion of said charge carriers to said second region (2). Over a part of its boundary, the first region (1) is separated from the third region (3) by a zone of the semiconductor layer (5) for creation of a depletion zone (9).