Photosensitive diode array storage target
AssigneeThomson-CSF
InventorsJean-Roger Gilles, Daniel Woehrn
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Abstract
A storage target comprising a photosensitive diode array which can be used to convert an optical image into an electronic image where the photo diodes are constituted by "hyper abrupt" junctions having a junction capacitance of wide dynamic range when reverse biased and having consequently a remanence which is variable as a function of the reverse voltage applied to them.
Claims8
A photosensitive target with storage properties for converting an optical image to an electronic image, comprising:
- a semiconductor substrate of a first conductivity type,
- upon said substrate, an array of zones of a second conductivity type forming, with said substrate an array of photodiodes,
- means for reverse biasing said photo-diodes,
- said photodiodes being constituted by "hyper-abrupt" junctions whose junction capacitance C varies in accordance with the reverse bias voltage V applied to them by said reverse biasing means, in proportion with V.sup.-.sup.m, where m>1/2,
- and upon said array of photo-diodes an array of insulating material zones, said insulating material zones being disposed between said photo-diodes.
A photosensitive target with storage properties for converting an optical image to an electronic image, comprising:
- an array of photo-diodes formed in a semiconductor substrate of a first conductivity type having a first kind of impurity,
- means for reverse biasing said photo-diodes,
- and an array of insulating material zones disposed between said photo-diodes,
- said photo-diodes being constituted (successively, working from the substrate towards the surface where are disposed said insulating material zones, by said substrate, by a first zone containing impurities of the same kind as those in said substrate, and by a second zone containing impurities of opposite kind to those in the substrate, the impurity concentration of said first zone being less than that of said second zone and more than that of said substrate, said photo-diodes thus being constituted by hyper-abrupt junctions.
In a photosensitive target with storage properties for converting an optical image to an electronic image when scanned by an electron beam, said target comprising:
- an array of photo-diodes formed into a surface of a N-type semiconductor substrate having a predetermined impurity concentration;
- means for reverse biasing said photodiodes;
- and an array of insulating material zones disposed onto said surface of said substrate between said photo-diodes;
- the improvement consisting in realising each of said photo-diodes by a hyperabrupt junction, each said photo-diode being constituted successfully working from the side of said substrate opposite said surface supporting said insulating material zones, to said surface supporting said insulating material zone by:
- (a) said N-type substrate having said predetermined impurity concentration,
- (b) a zone of the N-type having an impurity concentration higher than that of said substrate, and
- (c) a zone of the P-type having an impurity concentration higher than that of said N-type zone, said N-type zones being interposed between said P-type zones and said substrate in such a way that said P-type zones have no contact with said N-type substrate.
Dependencies are inferred from the claim text.