FR2689684A1 - Micro-imaging device for ionizing radiation. - Google Patents

Abstract

This device comprises a two-dimensional detector comprising a solid semiconductor material (2) capable of transforming incident ionizing radiation into electrical charges and having a first and a second parallel faces, a detection zone (4) defined in a central region of the solid material , a connection zone located at the periphery of the detection zone, at least a first system (10) for collecting charges consisting of an array of conductive metal electrodes, arranged on the first face of the material and comprising, in the zone detection, parallel microbands, the pitch (10a) of the electrodes widening in the connection zone so as to be compatible with a connection by microbeads, and the first reading circuits (14) of said charges, electrically connected to the first collection system by hybridization by microbeads in the connection area.

Description

i

  MICRO-IMAGING DEVICE FOR IONIZING RADIATION

DESCRIPTION

  The invention relates to a device for micro-imaging high ionizing radiation

  resolution, for non-destructive testing.

  The ionizing radiation to which the invention applies is X or

gamma.

  Ionizing radiation imaging allows the study of living or non-living matter by radiographic projection or tomographic reconstruction and thus allows the non-destructive analysis of the internal structure of objects of dimensions and masses.

irradiated variables.

  Obtaining high resolution images requires a source of ionizing radiation of extremely small size, which corresponds to a beam of parallel radiation. This condition is well solved in the case of

synchrotron beams.

  The device of the invention is intended in particular for radiological microimaging and microtomography of generally biological structures irradiated with low energy sources, less than 5 keV; irradiated metal alloys with average energy sources generally between 5 and 15 ke V, but also composite structures (ceramic or fibrous type) irradiated with energy sources greater than 15 ke V. The device of imaging of the invention can therefore be used in many fields of application, both in the medical and

biological than industrial.

  In industry, the invention applies for example in the fields of automotive, space, nuclear, building construction, etc. More specifically, the device of the invention relates to the detection part of the

ionizing radiation.

  Conventional ionizing radiation imaging devices using photosensitive films, image intensifiers, radiological screens coupled to photosensitive cameras make it possible, in real time, to obtain quality images but whose spatial resolution is of a few tens of micrometers. This resolution, due in part to the scattering of light in the X-ray or gamma-to-light radiation conversion layer, is sometimes reduced by the use of needle-like scintillating structures (eg Cs I crystals in intensifiers). radiological images) or

  structures whose shape is realized a posteriori.

  In the latter case, the resolutions are then

the order of 100 lm.

  Also, these conventional imaging devices can not be used when one seeks to analyze defects in a material, of the order of a micrometer. Another known two-dimensional imaging method, used in nuclear medicine, consists of a barycentric reconstruction using the Anger principle. For this purpose, a set of large photomultipliers, of the order of mm in diameter, recovers photons. from a thick scintillator (crystal Cs I) (transforming incident X radiation into light) and the location of this light spot is reconstructed by a resistance bridge associating the outputs of the different photomultipliers. When the desired spatial resolution is about ten micrometers, an array of electrodes is used for the barycentric reconstitution.

  microband type, arranged parallel to each other.

  For example, microbands arranged in steps of 50 m allow a location to 5 pm near

the X-matter interaction.

  Such a system is in particular described in the document Nuclear Instruments and Methods in Physics Research A 305 (1991), pp. 173-176, to Hietanen et al., "Beam test results of an ion-implanted silicon strip detector". mm wafer "It uses microstrips formed by ion implantation in silicon. This method of barycentric imaging unfortunately implements technological means

complex and bulky.

  When one is interested in microscopic structures, one uses integrated detection devices, based on the direct conversion of the ionizing radiation into electrical charges under the electric field Thus, one eliminates the lateral diffusion of

  the energy captured by the detection device.

  In these devices, use is made in particular of directly irradiated charge transfer devices (CCDs) which make it possible to achieve about ten micrometers of spatial resolution.

  CCDs are generally formed in silicon.

  A CCD device, commercial and two-dimensional, has so far pixels (or image points) of the order of 7 pm and the detection of ionizing radiation in the silicon substrate allows a location, with this accuracy, but only for X or gamma photons of low energy, that is to say energy <5 ke V The number of its

applications is therefore limited.

  In addition, the circuits for reading the charges created in the substrate, associated with these detectors, are also exposed to radiation and are therefore aging.

very bad.

  The imaging device of the invention is based on the principle of the barycentric localization

  of the energy of the radiation received by a semi-

  conductor, in a volume of 10 to 20 pm of medium size This principle is described in particular in the

US-A-4,411,059.

  In this document, the detection of gamma radiation is performed by diodes formed in silicon. This detection is carried out using row electrodes and column electrodes.

  located on both sides of the semi-

conductive.

  If these electrodes were made in the form of parallel micro-bands separated by a step of 5 μm, it is possible to locate the detection zone by barycentric reconstitution. A 10% accuracy on the pitch of the electrodes corresponds to a better location. as the micrometer on the point of impact of radiation. This method would therefore allow

  micrometric localization of ionizing radiation.

  As with charge transfer devices, the reading circuits, if they are exposed to

  ionizing radiation, age very badly.

  In the case of electrodes rows and columns very close together, the known imaging devices do not allow a reading of the charges collected by these electrodes, by appropriate reading circuits, because the pitch of these electrodes is not compatible with a soldered wire connection, by

  microbeads, or by any other means.

  The subject of the invention is therefore a novel X-ray or gamma-ray imaging device making it possible to remedy the various disadvantages mentioned above. In particular, this device ensures micrometric imaging. In addition, this device can be of small tail.

relatively simple to manufacture.

  More specifically, the subject of the invention is a device for microimaging an ionizing radiation comprising: A) a two-dimensional detector comprising a solid semiconductor material capable of transforming incident ionizing radiation into electrical charges and having a first and a second parallel face, a detection zone defined in a central region of the solid material, a connection zone located at the periphery of the detection zone, at least a first charge collection system consisting of a network of conductive metal electrodes disposed on the first face of the material and having, in the detection zone, parallel micro-bands, the pitch of the electrodes widening in the connection area so as to be compatible with a microbead connection, and B) first circuits for reading said charges, electrically connected to the first system of co L hybridization by microbeads

in the connection area.

  By micro-bands, it is necessary to understand bands spaced apart by a step <10 μm. In particular, the pitch of the electrodes in the detection zone is <5 m and

  The micro-strips have a width <4 μm.

  In the connection zone, the pitch of the electrodes is> 10 m; it can go up to 20 ° C. It is thus compatible with a microbead connection. In the micro-imaging device of the invention, the detection and measurement functions are dissociated and carried out by components

separated, hybrids.

  From Lus, it can be used with sources of radiation of energy higher than 15 ke V and

  therefore in a wide range of applications.

  It differs in particular from the barycentric detection devices known by the use of a semiconductor material, undoped, of high electrical resistance, either in the form of solid material, or in the form of a thin layer deposited on

an electrical insulating substrate.

  In addition, the reading circuits being located outside the detection zone, their aging

  premature irradiation is prevented.

  A solid semiconductor material detector, in accordance with the invention, can be used both for X-rays or gamma rays of low energy (<5 ke V) and for high-energy radiation (<15 ke V). a semiconductor thin film detector deposited on an insulating substrate is intended solely for the detection of very soft X or gamma rays whose energies are less than 5 ke V. This thin layer may be epitaxied by liquid or gaseous phase or may be deposited according to the technique of chemical vapor deposition (CVD) and all these variants, MOCVD for example This layer will, in principle, a thickness of lpm to 50 pim in order to stop the X-ray or gamma energy <ke V The insulating substrate may be made of any electrical insulating material also acting as thermal insulator As an insulating substrate, mention may be made of ceramics such as alumina and silica, glass s, polymers, etc. The semiconductor material of the detector of the invention must be able to transform the ionizing radiation into electrical charges. In particular, this material must be capable of transforming an X or gamma photon into a few hundred pairs of electron-holes; this semiconductor material must therefore have a high electrical resistivity, preferably higher than

ohm meter.

  The semiconductor material may be made of any known semiconductor material such as germanium, silicon, binary, ternary or quaternary alloys of elements III and V or elements II and VI of the Periodic Table. of the

elements.

  Preferably, the semiconductor is silicon, GaAs or Cd Te of high electrical resistivity. According to the invention, the imaging device may comprise one or two collection systems of

  loads, arranged on either side of the semi-

  in this case, second load reading circuits shall be electrically connected to the second collection system by

  hybridization by microbeads, in the connection zone.

  According to the invention, the collection of charges by a row electrode or a column electrode can be carried out over the entire dimension of the detector, the latter then working in photon counting by photon In this case, the second charge collection system is constituted a uniform conductive layer

  deposited on the entire detector.

  Preferably, the two charge collection systems are each constituted, in the detection zone, by parallel metallic conductive micro-bands, the conductive micro-bands of the first and second systems being crossed in directions forming between them an angle ranging from Advantageously, the common electrode but also the band electrodes of the two systems can be divided in two transversely, which then allows access to a higher photon count rate and / or an improvement in the

spatial resolution of the device.

  The reading of the electrical charges formed in the semiconductor material by each line and column must be made using very low noise reading circuits since the charge corresponding to a detected X or gamma photon is distributed over a few measurement channels (columns and lines) Also, these reading devices are arranged in the immediate vicinity of the detection zone, but outside of

  this one to not be irradiated.

  In order to improve the thermal noise performance of the read circuits, by lowering the latter, a cooling system can be provided. This system can consist of a structure with

Peltier effect.

  According to the invention, the reading circuits are hybridized on the semiconductor material thus making it possible to obtain a small imaging device. These reading circuits comprise, in particular, integrated transistors of the MOS type acting as amplifiers, each transistor being

associated with an electrode.

  Preferably, the outputs of these transistors are connected to electrical resistances connected together. Thus, it is possible to reconstruct the location of the incident beam according to the Anger principle. According to the invention, the reading circuits of the first and second electrode systems (for example Lines electrodes and column electrodes) can be located on either side of the semiconductor material. It is however possible to locate these reading circuits on one and the same side of the semiconductor material In this case, vias

  (or holes) can be provided in the semi-

  driver to allow the passage of drivers

  electrically from one side to the other of the material.

  Other features and benefits of

  the invention will emerge more clearly from the description which will

  follow, given by way of nonlimiting illustration, with reference to the appended figures, in which: Figure 1 shows schematically, in perspective, a microimaging device according to the invention, using hybridized reading circuits; FIG. 1A represents an alternative embodiment of the electrodes of the detector of the invention; Figure 2 is a longitudinal sectional view of the device of Figure 1; FIG. 3 diagrammatically represents, in plan view, a device according to the invention, using integrated reading circuits on the semiconductor detection material; FIG. 4 schematically represents, in perspective, an alternative embodiment of the device according to the invention, using hybridized reading circuits; FIG. 5 schematically illustrates, in perspective, another variant embodiment of the imaging device according to the invention, using a common electrode; FIG. 6 schematically represents, in longitudinal section, another variant embodiment of the device according to the invention in which the reading circuits are arranged on the same side of the semiconductor material; and FIG. 7 schematically shows, partially and in section, another variant embodiment of the device of the invention, using a

  thin semiconductor layer for detection.

  With reference to FIGS. 1 and 2, the ionizing radiation imaging device (X or gamma) in accordance with the invention comprises a two-dimensional detector formed of a detector plate 2 made of solid semiconductor material, the central portion 4 of which constitutes the detection area or imaging area The periphery of the semiconductor material 2

  is intended for reading circuits.

  According to the invention, the semi-material

  conductor 2 is silicon, gallium arsenide or such high-resistivity cadmium luride, typically resistivity greater than ohms cm The semiconductor plate 2 has a thickness typically from 100 to 4001 dm It ensures the transformation of the ionizing radiation 6 incident on the upper face of the plate 2 in electron-hole pairs which are collected by two electrode arrays respectively 8 and 10 deposited directly on the upper and lower surfaces

semiconductor 2.

  In a solid semiconductor, the detection 1 1 is made solely on the principle of the photoelectric interaction so that the spatial resolution is the

best possible.

  In the imaging zone 4, the electrodes 8 are in the form of micro-bands oriented parallel to each other in a direction x and the electrodes 10 have the form of micro-bands oriented parallel to each other in a direction y, perpendicular to the direction The electrodes 8 and 10 therefore define detection lines and columns in the imaging zone 4. These electrodes 8 and 10 are made, in the case shown, of conductive metal and in particular of aluminum, chromium, silver, tungsten, gold, etc. EL are produced for example by metal deposition by cathodic sputtering according to the "lift- off "(insolation of a photoresist through a mask representing the image of the electrodes to be made, development of the resin, deposition of the

  metal layer then dissolution of the resin).

  The electrodes have, in the detection zone, a width of 0.2 μm to 1.5 μm and are spaced at a pitch of 2 μm to 10 μm; their thickness is

at 300 nm.

  In the embodiment shown, the detection or imaging zone 4 has, in plan view, the shape of a square, the lower side of which is

to the mm.

  By way of example, an image zone 4 of 300 × 300 μm can provide an image of 500 × 500 pixels (elementary display points) after barycentric reconstruction for pixels (image points whose dimensions are fixed by the intersection of a line and a column of the detection zone) of 0.6 x, 6 m 2 0.6 x 0.6 m Of course, it is possible to envisage a detection zone of rectangular shape of a few mm. The barycentric methods allow a location of the beam incident on the detector better than the micrometer They allow the use of a detector as shown in Figure 1, at least 10 times smaller than those used until

  day in the field of X or gamma imaging.

  According to the invention, the two-dimensional detector comprises a connection or reading zone 11 situated at the periphery of the detection zone 4. In this zone 11, the pitch of the electrodes 8 and 10 is greater than that of the electrodes in the zone of detection and is typically chosen in the

range from 100 to 1000 m.

  This enlargement of the pitch of the electrodes in the connection zone can be achieved in different ways. By way of example, the electrodes 8 may comprise, at their ends, outside the detection zone 4, side branches 8a perpendicular to the direction x. The ends of the lateral branches 8a may be aligned along the diagonal z of the

  detector to enlarge their pace.

  Similarly, the electrodes 10 may have at their ends branches 10a perpendicular to the direction y whose pitch is greater than that of

  microbands in the detection zone.

  The branches 8a and 10a of the electrodes 8 and 10 may also be oriented in a direction forming an obtuse angle with the direction x, as shown in FIG. 1A. The branches 8a and 10a may furthermore not be parallel between they,

but arranged in a fan.

  Any other arrangement of the legs 8a and 8a has electrodes 8 and 10 increasing their pitch in the connection zone 11, in order to be compatible with a

  hybridization by microbeads, may be considered.

  At at least one of the two corners of the upper surface of the semiconductor wafer 2 and in the connection zone 11, there are integrated circuits 12 connected by a hybridization technique to the branches 8 to conductive electrodes 8 intended to to the reading of the electrical signals provided by these

électodes.

  Similarly, we find, at least one corner on

  two of the bottom surface of the semi-plate

  2 and in the zone 11 of connection, integrated circuits 14 connected according to the branch hybridization technique 10 has electrodes 10, for reading the electrical signals provided

by these electrodes.

  Hybridization of the two-dimensional detector and the reading circuits can be made by means of indium ball connectors, symbolized at 16. The connection of the circuits 12 and 14 respectively to the conducting electrodes 8 and 10 is carried out at the periphery of the material. semiconductor 2, where no connections have been enlarged enough to be

  compatible with this hybridization technology.

  Thus, the detection and reading functions are dissociated and can be optimized

independently of one another.

  In the variant shown in FIGS. 1 and 2, the electrodes 8 are divided into two groups

  19 and 20, each connected to a read circuit 12.

  Similarly, the electrodes 10 are divided into two

  groups, each connected to a read circuit 14.

  The reading circuits 12 and 14 comprising amplifiers respectively 18 and 20 with very low noise, located in the immediate vicinity of the detection zone 4; at each electrode 8 is connected an amplifier 18 and at each electrode 10 is connected an amplifier 20. These amplifiers are in particular MOS transistors made on a

  silicon substrate distinct from that of the detector.

  These sense amplifiers 18 and 20 can be read simultaneously (which corresponds to the embodiment shown in FIG. 1) or

  possibly independently of one another.

  The location of the incident beam 6 and therefore the processing of the signals supplied by the amplifiers 18 and 20 is carried out by dedicated circuits 22 and 24 respectively, located as far as possible from the detection zone 4, and in particular outside the semiconductor. These dedicated circuits are for example those known under the name of charge reading register and sold by THOMSON Company.

(TMS).

  According to the invention, to each amplifier

  can be associated with a dedicated processing circuit.

  However, it is preferable to use only two dedicated circuits as shown in FIG. 1 In this case, the current outputs of the amplifiers of the same group (here 19 and 21) will be connected to each other by a bridge of 26. This arrangement appears more clearly in FIG. 3, which represents, in a view from above, a detector according to the invention in which the reading circuits are integrated in the solid semiconductor 2 and no longer hybridized as shown in FIGS.

Figures 1 and 2.

  The description that follows will only concern the

  line network and their associated reading circuits, but it goes without saying that the column electrodes and their associated readout circuits arranged on the other side of the semiconductor 2 can be arranged according to

the same principle.

  In this FIG. 3, the upper electrodes, parallel to the x direction, bear the reference 28; they occur only in the form of parallel micro-bands between them and at the

direction x.

  The transistors 18 each connected to a line electrode 28 have their outputs interconnected by the resistor bridge 26 so as to obtain only two output signals -u and + u for the row electrodes x and I 1 and I for the column electrodes y The ratio of the signals respectively of the rows and the columns makes it possible to locate directly the point of impact of the incident beam on the detector. This ratio is calculated by the circuits

dedicated 22 and 24.

  The electrical signals supplied by the read circuits 12 and 14 respectively give, in time coincidence, the abscissa x and the ordinate y of the point of interaction of the radiation with the detector,

in known manner.

  In addition to the shape of the electrodes, FIG. 3 differs from FIGS. 1 and 2 by the use of a single dedicated external circuit 22 because the row electrodes 28 (and consequently the transistors

  18) are not divided into two groups.

  As shown in FIG. 4, it is possible to cut the upper electrodes and the lower electrodes in two equal parts in the y direction perpendicular to the micro-bands. Four groups 28, 30, 32 and 34 of upper electrodes can thus be obtained. each associated with a read circuit 12 identical to those previously described The detection, divided into four sectors, allows an improvement in the resolution

space or count rate.

  It is also possible, as shown in FIG. 5, to use one of the two electrode systems, for example the one supported by the upper face of the semiconductor 2, in the form of a common electrode 38 which covers all The size of the detection zone 4 of the detector Under these conditions, the detector works in photon counting

by photon.

  This common electrode 38 is of course connected at the output to an amplifier 18 located outside the detection zone 4 for example integrated in the semiconductor. The lower electrode array can be arranged as shown in FIG.

  cut into sectors as shown in FIG.

  Similarly, the common electrode 4 can be cut into two identical parts in a direction perpendicular to the x direction, which allows

  to access a count rate twice as large.

  In FIGS. 1 to 5, the reading circuits 12 and 14 respectively of the row electrodes and of the column electrodes were respectively arranged on the lower and upper faces of the semiconductor 2, respectively coated with

  electrodes lines and electrodes columns.

  However, it is possible, as shown in FIG. 6, to arrange the reading circuits 12 of the line electrodes on the lower face of the detector 2. For this purpose, vias 40 (or holes) are formed on the periphery of the semiconductor 2 The holes are filled with a conductive material 42 for connecting the electrodes 8 to electrical contact points 44 formed on the lower face of the semiconductor 2 and

  for connecting a read circuit 12.

  In the embodiment shown in FIG. 6, the read circuits 12 are hybridized circuits connected via indium balls 16

  at the electrical contact points 44.

  The holes 40 can be made by laser or ultrasound and the metallization of these holes is carried out either by chemical deposition or by vapor phase transport. Under these conditions, the reading circuits 12 and 14 respectively of the rows and columns can be formed. on the same chip reported on the semiconductor 2 The connection of the lines and the conductive columns with the reading circuits 12 and 14 is ensured as in FIG.

  The detector of the invention represented in FIGS. 1 to 6 included as detection material a solid semiconductor substrate 2 It thus allowed the detection of X or gamma radiation with energy of less than 5 ke V, energy between V and 15 ke V or with energy greater than 15 ke V. From p Lus, a cooling device 46 (see Figures 1 and 2) can be provided to improve the performance of the amplifiers, by reducing the thermal noise This device is especially necessary for energy radiation imaging above 5 ke V This cooling device

  consists of Peltier effect circuits.

  In the case of X-rays or very soft gamma, that is to say energy of less than 5 keV, it is possible to realize the detector of the invention, as

shown in Figure 7.

  This detector comprises an electrical and thermal insulating substrate 48, for example made of alumina, on the upper surface of which the lower electrode system 10 is made. These column electrodes may be made of tungsten or chromium according to the "lift-off" technique and to have the forms

  represented in FIGS. 1 to 4.

  The set of electrodes 10 is covered with a layer 50 of amorphous silicon or any other high-resistivity semiconductor material, a few micrometers thick. This layer 50 constitutes the detection layer of the ionizing radiation ensuring the transformation of this layer. influence

in electric charges.

  At the upper surface of the detector layer 50, the line electrodes 8 are oriented, at least in the detection zone, perpendicularly to the column electrodes 10. They are produced as previously described (FIGS. 1 to 4). In FIG. 7, the read lines 12 and columns 14 are reported by hybridization on the detection layer 50. They can of course be integrated in the layer 50. Moreover, these circuits

  may be on the same side of the semi-

  50, respectively on the upper surface of the layer 50 and on the sidewall, as shown in FIG. 7. Furthermore, these circuits are

  arranged on the same side of the substrate 48.

  According to the invention, these reading circuits are located at the periphery of the layer of

detection 50.

  The reading amplifiers integrated in the detection semiconductor (FIG. 3) or hybridized (FIGS. 1, 2) consist of NMOS transistors

  and / or PMOS according to the techniques of micro-

  electronic. Instead of using two metal electrode arrays, as described previously, it is possible to locate the incident gamma or X radiation using only one array of electrodes, for example the upper electrode array 8, associated with resistive connections In this case, it is sufficient to add on the upper metal electrodes and in known manner resistive lines formed for example to

  from ion diffusion in a semi-

  conductor different from that of the detector, each end then being connected to an amplifier to locate on the metal line the point of impact of the

X or gamma radiation.

  The determination of the impact of incident radiation when a resistive link is used is

  performed as described in US-A-4,411,059.

Claims (11)

  A device for microimaging ionizing radiation comprising: A) a two-dimensional detector comprising a solid semiconductor material (2, 50) adapted to transform incident ionizing radiation (6) into electric charges and having a first and a second second parallel faces, a detection zone (4) defined in a central region of the solid material, a connection zone located at the periphery of the detection zone, at least a first system (10) for collecting charges consisting of a network of conductive metal electrodes, disposed on the first face of the material and having, in the detection zone, parallel micro-bands, the pitch C (10a) of the electrodes widening in the connection zone so as to be compatible with a microbead connection, and B) first read circuits (14) of said charges, electrically connected to the first collection system by microbil hybridization the in the connection area.   2 Device according to claim 1, characterized in that a second charge collection system (8, 28, 38) is arranged on the second face of said material and at least opposite the metal micro-strips of the first system and in that second reading circuits (12) of said charges are electrically connected by microbead hybridization to the second   collection system in the connection area.   3 Device according to claim 2, characterized in that the second system (8, 28) for collecting charges consists of an array of electrodes comprising, in the detection zone, parallel conductive metal micro-bands, oriented perpendicular to the micro -bands   conductors of the first collection system.   4 Device according to any one of   Claims 1 to 3, characterized in that the micro-   bands have a step <5 Pm. Device according to any one of   Claims 1 to 4, characterized in that the step   electrodes in the connection area is> 10 μm.   6 Device according to any one of   Claims 1 to 5, characterized in that the material   semiconductor is a solid material (2) or a thin layer (50) deposited on an electrical insulating substrate. 7 Device according to any one of   Claims 1 to 6, characterized in that the material   semiconductor (2, 50) is made of silicon, gallium arsenide or high cadmium telluride electrical resistivity.   8 Device according to any one of   Claims 3 to 7, characterized in that the micro-   conductive strips of the first (10) and / or second (8, 28) system are cut transversely in two identical parts.   9 Apparatus according to any one of   Claims 2 to 8, characterized in that the   first and second read circuits (12, 14) are   arranged on the two opposite sides of the semi-   driver. Device according to any one of   Claims 2 to 8, characterized in that the   first and second readout circuits (12, 14) are arranged on the same side of the solid material, vias (40) being formed in said material to ensure the passage of electrical conductors (42) on the other side of the material, for at the electrical connection   circuits (12) mounted on this other side.   11 Device according to any one of   Claims 3 to 10, characterized in that the   first and / or second read circuits comprise transistors (18) playing the role of amplifiers,   each transistor being associated with an electrode.   Device according to claim 11, characterized in that the transistors of the first and / or second read circuits (12, 14) have outputs electrically connected to one another by means of electric resistors (26).   13 Apparatus according to any one of   Claims 3 to 12, characterized in that the micro-   conductive strips of the second collection system,   in the detection zone, are associated with micro-   bands scattered in the semiconductor material   (2), high electrical resistivity.   14 Apparatus according to any one of   Claims 3 to 13, characterized in that the   electrodes of the first and / or second collection system have, outside the detection zone, branches (8 a, 10 a) flared from the micro-strips respectively of the first and / or second system and used for connection of micro-bands to associated reading circuits.