Thomson-csf

Thomson Tubes Electroniques

Yves Henry

Paul De Groot

Claude Weisbuch

Bernard Munier

Marc Arques

Guy Moiroud

Michel Villard

Andre Nicollet

Claude Weibuch

Bernard Munter

Disclosed is a substrate particularly designed to bear an active structure made according to thin-film technology. The advantage of the disclosed substrate is that it can be made in large sizes and at low cost. To this end, the substrate 1 has an soda-lime glass plate passivated by means of two superimposed layers. The layer in contact with the glass plate is a barrier layer against the alkaline constituents and the layer deposited on the barrier layer has the function of preventing the effect, on the barrier layer, of the products designed to etch the elements that form the active structure.

Electrically insulating substrate

A radiological image detector of the type formed by a matrix of photosensitive elements, associated with a light source, enables a resetting of the voltages at the terminals of the photosensitive elements, the light source and the photosensitive matrix being connected to each other so as to give the image detector a particularly small thickness. To this end, the light source includes a stack of semiconducting layers forming at least one electroluminescent diode having, as its support, a substrate of the matrix.

Radiological image detector

The disclosure concerns devices for the conversion of images into electronic signals with particular application to X-ray imaging. Instead of forming, on an insulating glass substrate, a strip or matrix of photosensitive elements (PIN diodes) which are then coated with a scintillating sheet bonded to or pressed against the upper surface of the photosensitive elements, a scintillating layer is deposited on the substrate before forming the photosensitive elements. Thus, a gain in sensitivity and definition is achieved. It is moreover possible to preserve, in addition to the scintillating layer deposited between the substrate and the photosensitive elements, a scintillating layer bonded to or pressed against the upper surface of the unit. The two scintillators may be identical or different in nature. If they are different, they may react to different wavelengths but may also emit in different wavelengths.

X-ray imaging device

A photocathode having internal amplification includes a first electrode adapted for receiving a first voltage, and for transmitting received photons. An absorption layer is disposed adjacent the first electrode and comprises a P-type semiconductor material having a forbidden band of sufficiently small width to cause photons received through said first electrode to be converted into electron-hole pairs. At least one ionization-induced electron multiplication layer is disposed adjacent the absorption layer. Each such multiplication layer comprises two layers of N-type semiconductor material having respectively two different compositions at an interface therebetween. The two different compositions at the interface cause the multiplication layer, when biased, to accelerate the electrons received from the absorption layer to a degree greater than the acceleration provided to the holes received from the absorption layer. A second electrode is disposed adjacent the multiplication layer and receives a second voltage to cause the photocathode to be biased. In addition, the second electrode transmits the accelerated electrons received from the multiplication layer. An emission layer is disposed adjacent the second electrode and comprises a material which produces negative electron affinity to cause the accelerated electrons received from the second electrode to be emitted into a vacuum.

Photocathode having internal amplification

A photocathode having a low dark current comprises a first layer consisting of P.sup.+ type semiconductor material which is transparent to all wavelengths of the light to be detected, a second layer consisting of P.sup.+ type semiconductor in which the forbidden band is of sufficiently small width to convert the photons of the light to be detected into electron-hole pairs, at least one intercalary layer located within the second layer and consisting of P-type or N-type semiconductor material for creating a potential barrier with respect to the second layer, the thickness of said intercalary layer being of sufficiently low value to permit the passage of electrons by tunnel effect with high probability but of sufficiently high value to stop the greater part of a hole current, a metallic electrode for biasing the photocathode in order to accelerate the electrons of the electron-hole pairs created within the second layer by the light, a last layer for reducing the energy-gap potential with respect to the second layer in order to emit into the vacuum the electrons which have thus been accelerated.

Photocathode having a low dark current

In one example of construction, a high-performance photocathode has the following structure:

High-performance photocathode

The surface of a substrate which includes a plurality of photovoltaic junctions spaced along it is prepared as follows: a first anodic oxide layer is formed to cover the whole surface of the substrate and ensures perfect control of the photovoltaic junctions, a second layer is deposited of metal which is impervious to the radiation to be detected, then through photolithography, only the zones of the second layer that it is desired to render impervious to the radiation to be detected are maintained and the remainder removed; and finally, a layer of dielectric material is deposited to cover the whole surface.

Growing community of inventors

Eybens, France

Yves Henry