Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K39/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic radiation-sensitive element covered by group H10K30/00
  • H10K39/30—Devices controlled by radiation
  • H10K39/32—Organic image sensors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
  • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
  • H01L31/115—Devices sensitive to very short wavelength, e.g. X-rays, gamma-rays or corpuscular radiation
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K7/00—Constructional details common to different types of electric apparatus
  • H05K7/20—Modifications to facilitate cooling, ventilating, or heating
  • H05K7/2039—Modifications to facilitate cooling, ventilating, or heating characterised by the heat transfer by conduction from the heat generating element to a dissipating body
  • H05K7/20436—Inner thermal coupling elements in heat dissipating housings, e.g. protrusions or depressions integrally formed in the housing
  • H05K7/20445—Inner thermal coupling elements in heat dissipating housings, e.g. protrusions or depressions integrally formed in the housing the coupling element being an additional piece, e.g. thermal standoff
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
  • H10K30/30—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising bulk heterojunctions, e.g. interpenetrating networks of donor and acceptor material domains
  • H10K30/35—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising bulk heterojunctions, e.g. interpenetrating networks of donor and acceptor material domains comprising inorganic nanostructures, e.g. CdSe nanoparticles
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/10—Organic polymers or oligomers
  • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/549—Organic PV cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention relates to a radiation detector and a method of manufacturing this detector.
• the invention is particularly applicable to the two-dimensional detection of ionizing radiation such as, for example, X photons, gamma photons, protons, neutrons and muons.
• ionizing radiation such as, for example, X photons, gamma photons, protons, neutrons and muons.
• detectors having large areas and making it possible to replace the radiological films by digital imaging systems (in which the images are stored in digital form).
• digital imaging systems in which the images are stored in digital form.
• sensors detectors or sensors
• ultra-rapid acquisitions of images or temporal signals the acquisition time of an image possibly being as short as a picosecond. , the reading time may be longer.
• solid semiconductors which may be monocrystalline or polycrystalline or even amorphous
• silicon obtained by chemical vapor deposition
• diamond obtained by chemical vapor deposition
• CdTe CdTe
• GaAs GaAs
• the subject of the present invention is a radiation detector, a detector which is capable of having a large surface area and a low manufacturing cost.
• the detector which is the subject of the invention uses a composite material, the host matrix of which is a polymer, a material capable of being obtained, inexpensively, in the form of large area layers.
• the subject of the present invention is a detector of incident ionizing radiation consisting of first particles, this detector being characterized in that it comprises:
• Layers of a semiconductor composite material comprising a host matrix made of a polymer and guest particles of the semiconductor type which are dispersed in the host matrix, at least these guest particles being capable of interacting , directly or indirectly, with the radiation, electrical charges being generated in the layers of composite material during the interaction of the invited particles with the radiation,
• the detector being intended to be oriented so that the ionizing radiation arrives on the first face, the length of each sheet, counted from the first to the second face, being at least equal to one tenth of the mean free path of the first particles in the first material, the means for creating the electric field comprising, for each layer, a group of parallel and electrically conductive tracks which extend from the first to the second face, parallel to this layer, and which are in contact with it, the tracks also being intended to collect the charges which are generated in this layer by interaction of the latter with the second particles and possibly with the first particles and which are representative , in intensity and position, of the first particles, the electric field also being
• a polymer is chosen in which the mobility of the electric charges is greater than 10 "s cm 2 / V / s.
• This polymer is preferably chosen from the group comprising polyphenylenevinylene (abbreviated PPV), polythiophene, polyaniline, polypyrrole and polydiacetylene.
• PPV polyphenylenevinylene
• polythiophene polythiophene
• polyaniline polyaniline
• polypyrrole polydiacetylene
• the invited particles may be capable of producing the electric charges by direct interaction with the incident radiation or by indirect interaction with the latter, for example by interaction with other electric charges produced by interaction of the incident radiation with the host matrix.
• These invited particles can be chosen from the group comprising grains of at least one powder of a semiconductor and colloidal semiconductor particles.
• the invited particles have an average atomic number greater than 14, an average density greater than 2 g. cm "3 and an average relative permittivity greater than 10.
• the invited particles can be coated in a material which prevents their agglomeration.
• the first material is electrically conductive
• the tracks are electrically isolated from the sheets and the means for creating the electric field further comprise means for applying an electric voltage between the tracks and the sheets, this tension being able to cause the collection of the charges by the tracks.
• each group of tracks is contained in the layer with which it is associated.
• the first material is electrically conductive and the means for creating the electric field further comprise means for applying an electric voltage between the tracks and the sheets, this voltage being suitable to provoke the collection of charges by the tracks.
• the sheets are electrically insulating, an electrically conductive layer is interposed between each layer of semiconductor composite material and the sheet which is associated with it and the means for creating the electric field further comprise application means an electric voltage between the tracks and the electrically conductive layers, this voltage being capable of causing the charges to be collected by the tracks.
• the present invention also relates to a method of manufacturing the detector which is the subject of the invention.
• Figure 1 is a schematic and partial sectional view of a radiation detector useful for understanding the invention
• Figure 2 is a schematic top view of a particular embodiment of a radiation detector useful for understanding the invention
• Figure 3 is a schematic and partial perspective view of another particular embodiment of a radiation detector useful for understanding the invention
• Figure 4 is a schematic perspective view of a two-dimensional ionizing radiation detector according to the invention
• Figure 5 is a schematic and partial sectional view of the detector of Figure 4, along the plane P of this Figure 4
• Figure ⁇ is a schematic cutaway perspective view of an alternative embodiment of the detector of FIG. 4
• FIG. 7 is a schematic and partial perspective view of another alternative embodiment of the detector of the figure 4.
• the radiation detector which is schematically and partially shown in section in FIG. 1, is intended to detect incident radiation R.
• This detector comprises a layer MC of a composite material comprising a host matrix MH in which are dispersed solid guest particles PI.
• the thickness of this layer is for example of the order of 1 ⁇ m to 1 mm.
• the detector also includes two electrodes el and e2 between which the MC layer is included.
• this electrode (for example the electrode el) must be made of a material allowing this radiation R to pass.
• the host matrix M is made of a polymer.
• the proportion of particles invited into the host matrix is, for example, of the order of 1% to 70% by volume depending on the detector which it is desired to form. These guest particles are, if necessary, coated in a compound preventing their agglomeration.
• the polymer of the host matrix M can be semiconductor or electrically insulating.
• the electric charges reach the electrodes by conduction in the first case and by capacitive induction in the second case.
• a polymer is preferably used in which the electric charges have a mobility greater than 10 ⁇ 6 cm 2 / V / s.
• PPV polyphenylenevinylene
• polythiophene polyaniline
• polypyrrole polydiacetylene
• These polymers are all macromolecules whose "skeleton” has a periodic alternation of single bonds and double or triple bonds between carbon atoms or hetero atoms such as nitrogen.
• Such polymers are characterized by a high mobility of the holes, of the order of 10 "4 cm 2 / V / s to 1 cm 2 / V / s.
• An insulating polymer such as isooctane, having a high mobility of electrons, of the order of 10 ⁇ 4 cm 2 / V / s to 1 cm 2 / V / s is also usable.
• the invited particles which are introduced into the host matrix have a high stopping power with respect to the incident radiation R. They have the function of capturing this radiation (which can be X-ray or gamma radiation) and converting it into electrical charges.
• these invited particles should have an average atomic number, an average density and an average relative permittivity respectively greater than the average atomic number, the average density and the average relative permittivity of the polymer.
• guest particles are used having an average atomic number greater than 14, an average density greater than 2 g / cm 3 and an average relative permittivity greater than 10.
• These invited particles are preferably obtained from a powder of a semiconductor (for example
• CdTe, ZnS, ZnSe or ZnTe whose grains have sizes of the order of 1 n to 100 ⁇ m, or even colloidal particles of this semiconductor.
• a metal for example Zn, Ag or Mg
• a photoelectric material for example Csl or another material used for photocathodes
• the invited particles can also be chosen to convert ionizing particles such as electrons into electrons. secondary effects generated in the host matrix following the interaction of the latter with the incident radiation.
• the electrodes are intended for the application of the electric field allowing the transport, by the host matrix, of the charges generated by the invited particles. In certain detectors useful for understanding the invention, these electrodes also allow the collection of these charges and therefore the measurement of the current generated by the incident radiation in the layer of composite material, which allows the measurement of a flow rate of dose.
• Electrodes can be made of a metal (for example chromium, tungsten, silver or gold) or of a semi-metal (for example indium oxide or ITO that is- ie indium oxide doped with tin) but their nature can also be imposed by secondary functions which they may also have to provide, as will be seen below.
• a metal for example chromium, tungsten, silver or gold
• a semi-metal for example indium oxide or ITO that is- ie indium oxide doped with tin
• the material of which these electrodes are made is chosen to have a high cross-section effective with respect to this radiation: for example, a heavy metal such as lead or tungsten.
• the electric field applied, continuously or pulsed, to the layer of composite material via the electrodes (and an appropriate voltage source, connected between them) is for example of the order of 0.1 V / ⁇ m to 100 V / ⁇ m.
• the electrodes allow the definition of elementary points or "pixels" of these detectors. These electrodes can indeed form a wire mesh at the nodes of which the pixels are located.
• FIG. 2 shows, in top view, a detector useful for understanding the invention comprising a layer MC of composite material, a first row of parallel electrodes El which are formed on one face of this layer and a second row of parallel electrodes E2 which are formed on the other face of the layer MC and which are perpendicular to the row of electrodes El.
• Circuits C1 and C2 are provided to polarize the electrodes of the detector in order to create the electric field at each crossing of the electrodes.
• the pixels are simply delimited by the electric field prevailing between the electrodes.
• This is a metering type reading configuration.
• point electrodes such as “balls”, tips or pads, reported on a CCD or CMOS matrix, it is possible to obtain a mode of parallel reading of the images.
• Figure 3 This is schematically illustrated by Figure 3 in which we see another useful detector for understanding the invention comprising a layer MC of composite material, a two-dimensional network (“array”) of electrodes E3 formed on one side of this layer and an electrode E4 constituting a counter electrode and formed on the other face of the MC layer.
• the radiation R that we want to detect arrives in the direction of this layer E4 chosen to be transparent to this radiation.
• the charges generated by the invited particles under the impact of the incident radiation are electrons.
• the electrodes E3 are then grounded and a voltage source V is provided to bring the electrode E4 to a negative potential to create the electric field between the electrode E4 and each electrode E3.
• a CCD type CL circuit is provided for reading the signals supplied by the electrodes E3 when radiation is detected.
• the circuit CL comprises a two-dimensional network of electrode E5 forming pads which are respectively connected to the pads E3 by means of solder balls B.
• the pads E5 and therefore the pads E3) are grounded.
• the invited particles are used to convert the radiation into electrical charges (electrons or holes). Once thermalized, these charges, for example electrons, must leave the invited particles to be collected by the electrodes. In the case of guest semiconductor particles, it is possible to understand the electrical operation of the layer of composite material MC
• the electric field generated in the layer of composite material is applied unevenly between the polymer and the semiconductor .
• the ratio of the electric field E p applied to the polymer to the electric field E d applied to the semiconductor is proportional to the ratio ⁇ d / ⁇ p .
• the guest semiconductor particles convert the photons into electrical charges and thus become conductive.
• Their internal electric field E d then becomes close to 0, the whole electric field is applied to the polymer and E p becomes little different from (v / L) x (1-X 1/3 ) where X is the volume fraction of the particles invited.
• This strong variation of the internal electric field can favor an efficient migration of electrical charges in the polymer, which is favorable for a good signal-to-noise ratio for photodetection.
• the polymer of the composite layer of this detector or the invited particles must be electroluminescent in impulse mode ("electroluminescent AC"). It is also possible to add to the polymer of the composite layer an electroluminescent phosphor in pulse mode for example.
• the increase of the electric field in an electroluminescent polymer in impulse mode causes there an electroluminescence induced by field effect.
• the photo-induced current generated by the radiation in suitable semiconductor guest particles is capable of being detected or measured by the electroluminescence specific to these particles. You can use guest particles of
• ZnS Mn 2+ , CaS: Eu, SrS: Ce or various semiconductors in nanocrystalline state, such as porous silicon which can be prepared by cracking hydrides, by decomposition of chlorides by plasma or by electrochemical attack.
• a layer of composite material for example provided with crossed electrodes as in FIG. 2, and to polarize the electrodes so as to apply, to each crossing of these, an electric polarization field in the layer.
• the locally generated electroluminescence in this layer under the impact of the incident radiation is then detected by a two-dimensional network (not shown) of photodetectors which is placed opposite one of the faces of the layer of composite material.
• a layer of material is used.
• MC composite Figure 1 made of a polymer such as polythyophene with guest particles such as ZnS particles.
• Two conductive layers are formed on either side of this layer, one of which is exposed to solar radiation and transparent to the latter (it is for example made of ITO), a voltage is applied between these two conductive layers allowing create the electric field in the layer of composite material and the electrical charges generated in the layer of composite material are recovered, via the conductive layers, under the impact of solar radiation through a junction.
• a layer of composite material usable in the present invention can be produced in various ways.
• the polymer intended to constitute the host matrix is first dissolved in a solvent, for example toluene, then mixed with the semiconductor powder for example by means of a drum, a mixer-granulator or a granulating plate.
• a simple sedimentation may even be sufficient and the excess solvent is then poured in and then the remaining solvent is allowed to evaporate.
• the homogeneous mechanically prepared mixture can be extended.
• the solvent then evaporates and leaves a composite layer of a few hundred micrometers to several millimeters thick.
• the semiconductor powder mixed with an anti-caking agent compatible with the monomer intended to form the host matrix is mixed and, by polymerizing, this monomer traps the grains of the semiconductor.
• the deposition can take place on a cooled substrate, capable of supporting the monomer or the polymer in solution, or by simultaneous evaporation of the organic molecules, intended to form the matrix-host in polymer.
• the electrodes of a detector according to the invention can be for example made of metal or ITO or of conductive glass or of conductive polymer.
• Metal electrodes can be electrochemically deposited on the layer of composite material while electrodes made of conductive glass or of conductive polymer can be bonded to this layer.
• FIGS. 4 to 7 diagrammatically illustrate two-dimensional detectors of ionizing radiation which are produced in accordance with the invention. These detectors in FIGS. 4 to 7 use a semiconductor composite material. This means that its host matrix is of the insulating or semiconductor polymer type while its invited particles are of the semiconductor type.
• the ionizing radiation consists of X photons which have, for example, an energy of 5 MeV.
• the detector of FIGS 4 and 5 comprises a stack 2 of sheets 4 of an electrically conductive material which is capable of emitting electrons by interaction with 'the X-ray photons of the incident ionizing radiation.
• This detector also comprises layers 6 of a semiconductor composite material (whose host matrix is for example made of PPV and the invited particles for example made of CdTe) which alternate with the sheets 4 and whose invited particles are capable of being ionized by the photo-electrons emitted by the conductive material when the latter interacts with the X photons and possibly directly, although to a lesser extent, by the primary X photons.
• a semiconductor composite material whose host matrix is for example made of PPV and the invited particles for example made of CdTe
• Each of the layers 6 is associated with one of the sheets 4.
• the stack of sheets 4 and layers 6 has a first face 8 and a second face 10 which are opposite.
• Each of the faces 8 and 10 contains edges 12 of the sheets 4 and edges 14 of the layers 6 which alternate with the edges 12 of the sheets 4.
• the detector of FIGS. 4 and 5 is arranged so that the sheets 4 and the layers 6 are substantially parallel to the direction of the ionizing radiation to be detected and that this radiation arrives on the face 8.
• the length of each sheet 4, counted from face 8 to face 10, is at least equal to one tenth of the mean free path of X photons in the conductive material from which the sheets 4 are made.
• an incident X photon the trajectory of which has the reference 16 in FIGS. 4 and 5 interacts with the conductive material of a sheet 4 to produce, by Compton effect, photoelectric or creation of pairs, an electron of great kinetic energy, whose trajectory is represented by the arrow 18 in FIG. 5.
• the detector of FIGS. 4 and 5 also includes groups of parallel tracks 22 and electrically conductive which extend from face 8 to face 10, parallel to layers 6.
• Each group of tracks 22 is associated with one of the layers 6 and in contact with the latter.
• the tracks 22 are intended to collect charge carriers which are generated in the layers 6 by interaction of the invited particles thereof with the electrons resulting from the interaction of the incident X photons with the conductive material from which the sheets 4 are made.
• charge carriers are representative, in intensity and in position, of the incident X photons.
• the detector also comprises means 26
• FIG. 4 to create the electric field capable of causing the transport of the charge carriers and then the collection of these by the tracks 22.
• each group of conductive tracks 22 is contained in the layer 6 with which this group is associated.
• the means 26 are means for applying an electrical voltage between the tracks 22 and the sheets 4, this voltage being capable of causing the transport of the charge carriers and then their collection by the tracks 22.
• section plane P crosses the conductive tracks of the same row of tracks (row which is horizontal in FIG. 4), the tracks of this row belonging respectively to layers 6.
• each group of tracks is substantially contained in a plane perpendicular to the plane P and that this group extends substantially from the top of the layer 6 associated with the bottom of the latter.
• the material constituting the sheets 4 is still electrically conductive but the tracks 22 are no longer contained in the layers 6: each group of tracks is at the interface of the corresponding layer 6 and the sheet of conductive material which is associated with an adjacent layer 6.
• an electrically insulating material is provided to insulate the tracks 22 of the sheets 4 of conductive material, but the same means 26 can still be used as above.
• the detector of FIGS. 4 and 5 is provided with an electronic device 30 for reading the signals. electrics supplied by tracks 22 when these collect the charge carriers.
• each track 22 is bent to extend over an edge 14 of the corresponding layer 6, this edge being located on the face 10 of the stack of sheets 4 and layers 6 .
• the electronic reading device 30 comprises electrically conductive pads 34 which are respectively in contact with the curved ends 32 of the tracks 22.
• This contact can be made by means of solder balls 36, for example indium balls, or by means of electrically conductive wires or even by applying the curved ends of the tracks against the pads of the associated reading device, by suitable means, for example by pressing or with an electrically conductive adhesive. It is specified that the pads 34 are arranged in the same pitch as the curved ends 32 of the tracks 22.
• the conductive sheets 4 can be set to a negative potential and the conductive pads 34 (and therefore the tracks 22) to ground or ground the sheets 4 and the conductive pads 34 (and therefore the tracks 22) to a positive potential.
• the holes generated in the layers 6 are attracted by the sheets 4 of conductive material while the electrons generated in these layers 6 are attracted by the tracks 22 and collected by them, thus providing electrical signals which are read. thanks to the device 30.
• the sheets 4 can be brought to a positive potential and the studs 34 are grounded or the sheets 4 are grounded and the studs 34 are brought to a negative potential.
• the electrons are attracted to the sheets and the holes are attracted to the tracks and collected by them, still providing electrical signals which are read by the device 30.
• the tracks 22 convert, in digital and electrical form, the analog image which is transported by the X-rays which are detected.
• all the tracks 22 are grounded by means of the electrically conductive pads 34 and all the sheets of conductive material 4 are brought to a negative potential thanks to a voltage source. 38.
• the tracks 22 collect electrons.
• a negative potential for example equal to -500 V
• an electrically insulating plate 40 is used on one face of which electrically conductive parallel tracks 42 are formed, the pitch of which is equal to that of the sheets 4.
• All of these tracks 42 are connected to a track 44 also formed on this face of the plate 40 and this track 44 is connected to the negative voltage source 38.
• the face of the plate 40 carrying the tracks 42 is then applied. the stack 2 on which the edges of the sheets 4 also appear, this face being different from the faces 8 and 10, so that the tracks 42 respectively come into contact with the edges of the sheets 4, which makes it possible to carry all these sheets 4 to the desired negative potential.
• the plate 40 is for example made of ceramic or polymer and the tracks 42 and 44 of gold.
• the elements 38, 40, 42 and 44 constitute the means 26 mentioned above.
• the electronic reading device 30 is of the type used in CCD sensors.
• the tracks 22 of the stack 2 can be directly connected to the pixels of a CCD sensor without coating (“coating”).
• a connection matrix can be provided intermediate between tracks 22 of stack 2 and the reading device, for example of the CCD type.
• the conductive pads 34 are then located on one of the faces of this matrix to be respectively connected to the curved ends 32 of the tracks 22 and these pads are electrically connected to the pixels of a reading device for example of the CCD type via of electrical connections that cross this matrix.
• the thicknesses of the sheets 4 of conductive material (or insulator as will be seen below) and of the layers 6 are fixed to optimize the spatial resolution of the detector and the conversion efficiency (conversion and collection of charges).
• the smallest possible thicknesses are sought, typically of the order of 100 ⁇ m to a few hundred micrometers.
• sheets 4 of conductive material whose thickness is of the order of 200 ⁇ m and layers 6 whose thickness is of the order of 200 ⁇ m.
• the structure of a detector of the kind of that of FIGS. 4 and 5 makes it possible, compared with the hole detectors known from documents [1] and [2], to dramatically improve the efficiency (of of the order of 50%), with an appropriate thickness of material according to the direction of the radiation to be detected, and the spatial resolution which can be of the order of 100 ⁇ m by choosing an appropriate pitch for the tracks 22.
• the spatial resolution is determined by the pitch between the sheets 4 and between the tracks (which can be of the order of 50 ⁇ m to 200 ⁇ m).
• a heavy metal is preferably used, for example tungsten or lead.
• a 2 cm thick detector is used (counted from side 8 to side 10 of the Figure 1), layers 6 100 ⁇ m thick in PPV where CdTe particles are dispersed, and tungsten sheets 4 400 ⁇ m thick with tracks 22 in steps of 0.5 mm. These dimensions can be reduced if necessary, a step of 100 ⁇ m being technologically feasible.
• the sheets 4 of conductive material can be produced by any method.
• This surface must be sufficiently conductive and not oxidized. This surface can be coated, if necessary, with a metal deposit more suitable for producing ohmic contact with the material of the layers 6, for example a layer of gold.
• tracks 22 which may be made of gold or a metal better suited to semiconductor composite material used, we can proceed as follows:
• a first thickness of semiconductor composite material (for example 50 ⁇ m) is formed, as indicated above, on one of the faces of one of the conductive sheets 4,
• - Gold tracks 22 are deposited, for example having a width of 5 ⁇ m by evaporation through a mask or by a photolithography process, on the semiconductor composite material thus deposited, and
• a second thickness of semiconductor composite material is deposited on the first thickness so as to cover the tracks 22 and to obtain the desired total thickness of semiconductor composite material (for example 100 ⁇ m).
• the conductive sheets 4 thus covered are then stacked so as to obtain the alternation of conductive sheets 4 and layers 6 and are kept in contact with each other by a slight pressure which is exerted by suitable means, for example a mechanical device , or with an electrically conductive adhesive.
• the detector according to the invention differs from that of FIG. 4 by the fact that the sheets 4 are electrically insulating, for example made of plastic, in the case of FIG. 6, with a view to detecting, for example, neutrons, and by the fact that there is interposed between each sheet of insulating material 4 and the layer 6 corresponding to a thin layer (thickness of the order of 5 ⁇ m to 10 ⁇ m) electrically conductive 46, for example made of gold or copper, as seen in FIG. 6.
• FIG. 7 is a schematic and partial perspective view of an alternative embodiment of the detector of FIG. 4.
• each layer 6 is a sheet of juxtaposed wires 6a made of the semiconductor composite material, each wire containing, along its axis, a metal wire constituting a track 22.
• the wires 6a provided with these tracks 22 can be obtained by extrusion.

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