Punchthrough resetting JFET image sensor
First Claim
1. A semiconductor imaging device, comprising a common semiconductor body comprising an array of plural field effect transistors each having a first gate electrode, a source region and a drain region of one type conductivity adjoining the first gate electrode and defining therebetween a one type conductivity channel region, said first gate electrode comprising a zone of the opposite type conductivity forming a photosensitive p-n junction with the channel region, said first gate zones being electrically floating, some of said field effect transistors having different threshold voltages, and means for electrically charging the first gate zones of each transistor to a reverse potential substantially equal to its threshold voltage producing a depletion region extending from the photosensitive p-n junction in each transistor that just blocks the channel region, whereby the absorption of substantially equal quantities of radiation by each transistor will cause substantially the same change in conduction of its channel.
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Abstract
A solid-state picture pick-up device according to the invention comprises a number of field effect transistors in which the channel region is bounded by two oppositely located gate electrodes each forming a rectifying junction with the channel region and in which the photosensitive junction is formed by a gate electrode which shows a floating potential. Said gate electrode may be charged by simultaneously applying to the other gate electrode a voltage pulse of a sufficiently large amplitude so that punch-through occurs between the gate electrodes.
Since in this manner each transistor may be adjusted at its own threshold voltage, the influence of the spreading in the threshold voltages on the output signals is considerably reduced.
26 Citations
13 Claims
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1. A semiconductor imaging device, comprising a common semiconductor body comprising an array of plural field effect transistors each having a first gate electrode, a source region and a drain region of one type conductivity adjoining the first gate electrode and defining therebetween a one type conductivity channel region, said first gate electrode comprising a zone of the opposite type conductivity forming a photosensitive p-n junction with the channel region, said first gate zones being electrically floating, some of said field effect transistors having different threshold voltages, and means for electrically charging the first gate zones of each transistor to a reverse potential substantially equal to its threshold voltage producing a depletion region extending from the photosensitive p-n junction in each transistor that just blocks the channel region, whereby the absorption of substantially equal quantities of radiation by each transistor will cause substantially the same change in conduction of its channel.
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2. A semiconductor imaging device, comprising a common semiconductor body comprising plural field effect transistors each having a first gate electrode, a source retion and a drain region of one type conductivity adjoining the first gate electrode and defining therebetween a one type conductivity channel region, said first gate electrode comprising a zone of the opposite type conductivity forming a photosensitive p-n junction with the channel region, said first gate zones being electrically floating;
- and means for electrically charging said first gate zones to a reverse potential producing a depletion region extending from the photosensitive p-n junction across the channel region, absorption of radiation causing retraction of the depletion region, said first gate charging means comprising for each transistor a second gate electrode located adjoining the channel region so that the latter extends between the first and second gate electrodes and forming a rectifying junction with the channel region and an electrical connection to the second gate electrode for applying a voltage thereto; and
means connected to the source and drain regions of each transistor for deriving an electrical signal indicating the conduction condition of each channel region. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- and means for electrically charging said first gate zones to a reverse potential producing a depletion region extending from the photosensitive p-n junction across the channel region, absorption of radiation causing retraction of the depletion region, said first gate charging means comprising for each transistor a second gate electrode located adjoining the channel region so that the latter extends between the first and second gate electrodes and forming a rectifying junction with the channel region and an electrical connection to the second gate electrode for applying a voltage thereto; and
Specification