Matrix of photosensitive elements combining a phototransistor with a storage capacitor
AssigneeThomson-CSF
InventorJean L. Berger
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Abstract
Disclosed is a matrix of photosensitive elements for imaging. This matrix comprises, in series between a row conductor and a column conductor, a capacitor in series with a NIPIN or PINIP type phototransistor. This phototransistor can be made conductive, for the reading of the charges stored in the memory, as easily as a photodiode, even in darkness. The phototransistor is preferably formed by a stacking of N type, intrinsic type, P type, intrinisic type and N type semiconducting layers.
Claims8
A network of photosensitive cells arranged in rows and columns, each of said cells being located at the intersection of a respective row conductor and a respective column conductor, and wherein each of said cells comprises a series arrangement of a capacitor and an open base. phototransistor, said series arrangement being connected between the respective row conductor and the respective column conductor of each of said cells, said phototransistor comprising a superimposition of at least four semiconductor layers including:
- a first type conductivity first layer;
- a second layer of very low doping which is substantially an intrinsic semiconductor;
- a second conductivity type third layer opposite to said first type layer;
- a very low doping fourth layer which is substantially intrinsic.
Dependencies are inferred from the claim text.