WO2009115466A1 - Device for detecting ultraviolet radiation of the hybrid ebcmos type, comprising a membrane insensitive to solar radiation - Google Patents

Device for detecting ultraviolet radiation of the hybrid ebcmos type, comprising a membrane insensitive to solar radiation Download PDF

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Publication number
WO2009115466A1
WO2009115466A1 PCT/EP2009/053007 EP2009053007W WO2009115466A1 WO 2009115466 A1 WO2009115466 A1 WO 2009115466A1 EP 2009053007 W EP2009053007 W EP 2009053007W WO 2009115466 A1 WO2009115466 A1 WO 2009115466A1
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Prior art keywords
layer
concentration
membrane
aluminum
photocathode
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PCT/EP2009/053007
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French (fr)
Inventor
Jean-Luc Reverchon
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Thales
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/49—Pick-up adapted for an input of electromagnetic radiation other than visible light and having an electric output, e.g. for an input of X-rays, for an input of infrared radiation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components 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
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14643—Photodiode arrays; MOS imagers
    • H01L27/14658—X-ray, gamma-ray or corpuscular radiation imagers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components 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
    • H01L27/144—Devices controlled by radiation
    • H01L27/146—Imager structures
    • H01L27/14683—Processes or apparatus peculiar to the manufacture or treatment of these devices or parts thereof
    • H01L27/14694—The active layers comprising only AIIIBV compounds, e.g. GaAs, InP
    • 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 at least one potential-jump barrier or surface barrier, e.g. phototransistors
    • H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
    • H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier
    • H01L31/103—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the PN homojunction type
    • H01L31/1035—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the PN homojunction type the devices comprising active layers formed only by AIIIBV compounds
    • 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 at least one potential-jump barrier or surface barrier, e.g. phototransistors
    • H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
    • H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier
    • H01L31/108—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the Schottky type
    • 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 at least one potential-jump barrier or surface barrier, e.g. phototransistors
    • H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
    • H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier
    • H01L31/108—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the Schottky type
    • H01L31/1085—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the Schottky type the devices being of the Metal-Semiconductor-Metal [MSM] Schottky barrier type
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J1/429—Photometry, e.g. photographic exposure meter using electric radiation detectors applied to measurement of ultraviolet light

Definitions

  • EBCMOS hybrid type ultraviolet radiation detection device comprising a membrane insensitive to solar radiation
  • the field of the invention is that of devices for detecting ultraviolet radiation in the absorption band of solar radiation, that is to say in a spectral band whose wavelengths are less than 280 nanometers, spectral range known under the name: "solar-blind". It is known, in fact, that the solar radiation emitted in this area of the ultraviolet is absorbed by the ozone layer.
  • FIG. 1 represents the solar irradiance E as a function of the wavelength expressed in nanometers. Between 300 nanometers and 280 nanometers, the illumination E due to solar radiation falls by more than ten orders of magnitude and becomes insignificant. Therefore, this spectral band of less than 280 nanometers can be used to detect any radiation of human origin without being parasitized by solar radiation. There are many industrial, scientific and military applications.
  • the fluxes to be detected in these wavelengths are generally very small and photocathode devices are generally used for the detection of single photonic events.
  • photocathodes are not specifically sensitive to ultraviolet radiation and it is necessary to filter the visible radiation.
  • This filtering is performed by a filter called "solar blind". Visible flow rejection constraints being more than eight orders of magnitude over a few nanometers, the filter is not simple to achieve and has a limited transmission of the order of 10% due to the accumulation of filtering materials. It also has a low angular tolerance due to the interferential nature of certain optical elements that compose it.
  • a photocathode is a material capable of converting light radiation into electrons by secondary emission.
  • the photocathode may be a metal layer with a weak electronic extraction work. It can also be a layer of semiconductor material which has the advantage of presenting a better spectral selectivity.
  • gallium nitride GaN or aluminum-gallium nitride AIGaN also have a so-called "negative" electronic affinity: the energy level of the electrons in the conduction band is greater than that of the so-called empty.
  • the electrons must pass the potential barrier present on the surface of the photocathode. This problem is solved by lowering the level of the barrier obtained by the metallization of the semiconductor material layer or by an adequate orientation of the conduction bands.
  • the material of the photocathode is characterized by a structure and atomic levels positioned with respect to the vacuum level.
  • the Fermi level characterizes the level of filling of the electronic levels.
  • the electric field applied to the sample towards the outside defines the potential difference between the Fermi levels on either side of the interface. It makes it possible to exceed the energy difference existing between the energy of the electrons in the conduction band and the level of the vacuum beyond the material. The electrons can then escape with some kinetic energy.
  • the reduction of the electron output work can be achieved by using deposits based on metal layers.
  • the material used may be cesium, cesium oxide or barium.
  • Metals are used to set the Fermi level at the surface to bring the energy level closer to the electrons in the vacuum level conduction band. This further allows the electrons to be accelerated to the surface. Structures comprising a gradual variation of the respective percentages of semiconductor materials of AIGaN and InGaN type make it possible to accentuate this acceleration.
  • metal layers to reduce the output work of emitted photo electrons these are provided by the metal itself. It is therefore advantageous to replace the metal with a preferentially p-type semiconductor in which the electrons that can be emitted are those which succeed the absorption of a photon of energy greater than the "gap", that is to say the energy separating the valence band from the conduction band. This gives a spectral selectivity.
  • direct gap semiconductors such as indium arsenide can be used.
  • a complete ultraviolet light detection device generally comprises a photocathode and an electronic amplification device introducing a gain into the detection chain.
  • the traditional technology is based on the use of photocathodes and wafers of amplification and electronic multiplication, so-called “MCP” technology for "Multi Channel Plate”.
  • MCP photocathodes and wafers of amplification and electronic multiplication
  • FIG. 2 It comprises a transmission photocathode 1 and a microchannel slab 10 (drawing on the left of FIG. 2).
  • the micro-channels 10 amplify the primary electrons e " emitted by the photocathode 1 under the effect of a photon radiation" hv ", each primary electron e " giving several secondary electrons each time it hits the wall 1 1 of a micro-channel as shown in the drawing on the right of Figure 2.
  • the electronic flux is finally applied to a phosphorescent screen whose image is then transferred to a sensor type "CCD” via an adapter to optical fiber also called “tap". Its function is to adapt the dimension of the image to that of a conventional imager of "CCD” or "CMOS” type.
  • Other solutions based on delay line coils allow temporal analysis of the detected signal with a time resolution of a few nanoseconds.
  • a third channel implements the direct electron bombardment of secondary electrons from the photocathode on "CCD” and / or “CMOS” type sensors thinned to be sensitive to little penetrating radiation in the material, such as ultraviolet radiation or radiation.
  • CMOS complementary metal-Oxide Semiconductor
  • FIG. It essentially comprises a photocathode 1, an electronic amplification matrix 2 and a matrix device 3 of the CMOS or CCD type.
  • CMOS or CCD is a monolithic component.
  • the device comprises a "solar-blind" detection matrix connected to a multiplexer in "hybrid CMOS” configuration, making it possible to considerably reduce the effect of visible photons.
  • the subject of the invention is a device for detecting ultraviolet radiation of the "hybrid EBCMOS" type comprising a photocathode and a matrix detector arranged to detect the electrons emitted by said photocathode, said detector comprising a membrane collector of said electrons, characterized in that said membrane is made of a material called “solar-blind", that is to say in a material whose optical absorption is almost zero for optical radiation whose wavelengths are less than or equal to
  • the material of said membrane may be diamond or at least one of the materials of said membrane is a semiconductor material belonging to the (Ga, Al) N family.
  • the membrane is a "Schottky" diode type structure comprising at least three layers of AlGaN, the first layer having a first concentration of aluminum, the third layer having a second concentration of aluminum less than the first concentration, the first layer being separated from the third layer by a second layer whose aluminum concentration continuously varies from the value of the concentration of the first layer to the value of the concentration of the third layer, the second layer being doped n-type.
  • the membrane is a structure of the type
  • PIN comprising at least four layers of AIGaN, the first layer having a first concentration of aluminum, the third layer having a second aluminum concentration lower than the first concentration, the first layer being separated from the third layer by a second layer whose The concentration of aluminum varies continuously from the value of the concentration of the first layer to the value of the concentration of the third layer, the second layer being doped of type n, the fourth layer being p-doped.
  • the difference in aluminum concentration between the first and third layers may be of the order of 20%.
  • the photocathode may be a structure comprising at least one layer of semiconductor material belonging to the (Ga 1 Al) N family.
  • the crystallographic configuration of the hexagonal mesh of the GaN molecule is either (0001) or ( ooo ⁇ ), either (loo) or (l2o).
  • Figure 1 already described represents the variation of solar irradiance in the spectral band between 260 and 400 nanometers
  • FIG. 2 shows a device according to the prior art technology called "MCP"
  • FIG. 3 shows a sectional view of a device according to the prior art technology called "EBCMOS or EBCCD"
  • FIG. 4 represents a cross-sectional view of a device according to the invention with “hybrid EBCMOS”technology
  • FIG. 5 represents a sectional view of a first embodiment of the membrane of the device according to the invention
  • FIG. 6 represents a sectional view of a second embodiment of the membrane of the device according to the invention.
  • the photons "hv" not absorbed in the photocathode 1 pass therethrough and then are absorbed by the membrane 2 without producing electrons.
  • It may, for example, be a membrane made of family material (Ga 1 Al) N or diamond.
  • the stiffness of the cutoff front such as must be presented a "solar blind” filter in the ultraviolet is not required to the extent that there is no need to transmit the ultraviolet.
  • the useful electrons coming from the photocathode and originating from the ultraviolet radiation are amplified by the membrane 2 and are collected by the contacts 31.
  • Each primary electrical contact 31 is connected to a multiplexing or "multiplexer" 3 matrix device via beads. connection 32, the contacts are isolated from each other by an insulating dielectric 33.
  • the layer 22 disposed in front of the membrane is a sacrificial layer to reduce the dislocation rate and improve the crystalline quality of the material. Electrical protections of the "multiplexor" 34 complete the device.
  • the membrane can be made of diamond.
  • the diamond has a high mobility which makes it possible to collect the electrons absorbed by back side while preserving a substrate of a hundred microns.
  • the large diamond gap (5.5eV) decreases the number of electron-hole pairs formed by the accelerated carriers.
  • the membrane When the membrane is made of AIGaN, it may be a "Schottky” diode type structure, a “MSM” type diode structure or a "P. I. N” type structure.
  • the structure comprises at least three layers of AIGaN disposed on a substrate 20, the first layer 21 having a first concentration of aluminum, the third layer 23 comprising a second aluminum concentration lower than the first concentration, the first layer 21 being separated from the third layer by a second layer 22 whose aluminum concentration varies continuously from the value of the concentration of the first layer to the value of the concentration of the third layer, the second layer being n-type doped.
  • the thickness of the first layer can be 1 micron
  • the thickness of the second layer can be 0.2 micron and that of the third layer of 0.6 micron
  • the doping of the second layer can be done with a dopant concentration equal to or greater than 2.10 9 particles. cm "3.
  • the first layer may be removed partly with the substrate to facilitate the carrier collection.
  • a variant of this device consists of a Metal - Semiconductor - Metal (MSM) structure composed of two polarized Schottky contacts where only layers 21 and 22 are present.
  • MSM Metal - Semiconductor - Metal
  • the membrane is a PIN type structure comprising at least four AIGaN layers disposed on a substrate 20, the first layer 21 having a first concentration of aluminum, the third layer 23 comprising a second concentration aluminum lower than the first concentration, the first layer 21 being separated from the third layer 23 by a second layer 22 whose aluminum concentration varies continuously from the value of the concentration of the first layer to the value of the concentration of the third layer, the second layer being doped with type n, the fourth layer 24 being p-type doped.
  • the thickness of the first layer may be 1 micron
  • the thickness of the second layer may be 0.2 micron
  • Doping of the second and fourth layers can be done with a dopant concentration equal to or greater than 2.10 9 particles. cm "3 .
  • the first layer may be partially removed with the substrate to facilitate the collection of carriers.
  • the difference in aluminum concentration between the first and the third layer may be of the order of 20%.
  • the concentration may vary between 0 and 25% or between 45 and 65%.
  • the photocathode 1 it is possible to facilitate the emission of electrons by using the nitrogen polarity of the material most suitable for accelerating the carriers towards the surface while benefiting from a low output work.
  • the photocathode may be a structure comprising at least one layer of semiconductor material belonging to the (Ga, Al) N family. It replaces the dipole formed between the cesium atoms and the semiconductor layer. It provides electrons only after photon absorption, unlike the meshes that are metallic. P-doping or an insulative character is then required.
  • the crystallographic configuration of the hexagonal mesh of the GaN molecule is either (0001) or (ooo ⁇ ) or (lToo) or (ll2 ⁇ ) using the conventional notations of crystallography.

Abstract

The invention pertains to the field of devices for detecting ultraviolet radiation, of the hybrid EBCMOS type that comprises a photocathode (1) and a matrix detector (3) arranged so as to detect the electrons emitted by the photocathode, wherein the detector includes a membrane (2) for collecting said electrons. In the device according to the invention, the membrane is made of so-called solar-blind material, i.e. a material having a cut-off wavelength lower than or equal to 280 nm. The material can be diamond, or one of the materials of said membrane is a semi-conducting material selected from the group (Ga, AI)N.

Description

Dispositif de détection du rayonnement ultraviolet de type EBCMOS hybride comportant une membrane insensible au rayonnement solaire EBCMOS hybrid type ultraviolet radiation detection device comprising a membrane insensitive to solar radiation
Le domaine de l'invention est celui des dispositifs de détection du rayonnement ultraviolet dans la bande d'absorption du rayonnement solaire, c'est à dire dans une bande spectrale dont les longueurs d'onde sont inférieures à 280 nanomètres, domaine spectral connu sous l'appellation : « solar-blind ». On sait, en effet, que le rayonnement solaire émis dans ce domaine de l'ultraviolet est absorbé par la couche d'ozone. La figure 1 représente l'éclairement solaire E en fonction de la longueur d'onde exprimée en nanomètres. Entre 300 nanomètres et 280 nanomètres, l'éclairement E dû au rayonnement solaire chute de plus de dix ordres de grandeur et devient insignifiant. Par conséquent, on peut utiliser cette bande spectrale inférieure à 280 nanomètres pour détecter tout rayonnement d'origine humaine sans être parasité par le rayonnement solaire. Les applications tant industrielles que scientifiques ou militaires sont multiples.The field of the invention is that of devices for detecting ultraviolet radiation in the absorption band of solar radiation, that is to say in a spectral band whose wavelengths are less than 280 nanometers, spectral range known under the name: "solar-blind". It is known, in fact, that the solar radiation emitted in this area of the ultraviolet is absorbed by the ozone layer. FIG. 1 represents the solar irradiance E as a function of the wavelength expressed in nanometers. Between 300 nanometers and 280 nanometers, the illumination E due to solar radiation falls by more than ten orders of magnitude and becomes insignificant. Therefore, this spectral band of less than 280 nanometers can be used to detect any radiation of human origin without being parasitized by solar radiation. There are many industrial, scientific and military applications.
Bien entendu, les flux à détecter dans ces longueurs d'onde sont généralement très faibles et on utilise généralement des dispositifs à photocathode permettant la détection d'événements photoniques uniques.Of course, the fluxes to be detected in these wavelengths are generally very small and photocathode devices are generally used for the detection of single photonic events.
Ces photocathodes ne sont pas spécifiquement sensibles qu'au rayonnement ultraviolet et il est nécessaire de filtrer le rayonnement visible. Ce filtrage est réalisé par un filtre dit « solar blind ». Les contraintes de rejet du flux visible étant de plus de huit ordres de grandeur sur quelques nanomètres, le filtre n'est pas simple à réaliser et a une transmission limitée de l'ordre de 10% due à l'accumulation des matériaux de filtrage. Il présente également une faible tolérance angulaire due à la nature interférentielle de certains éléments optiques qui le composent.These photocathodes are not specifically sensitive to ultraviolet radiation and it is necessary to filter the visible radiation. This filtering is performed by a filter called "solar blind". Visible flow rejection constraints being more than eight orders of magnitude over a few nanometers, the filter is not simple to achieve and has a limited transmission of the order of 10% due to the accumulation of filtering materials. It also has a low angular tolerance due to the interferential nature of certain optical elements that compose it.
Une photocathode est un matériau capable de convertir un rayonnement lumineux en électrons par émission secondaire. La photocathode peut être une couche de métal présentant un travail d'extraction électronique faible. Elle peut également être une couche en matériau semi-conducteur qui a l'avantage de présenter une meilleure sélectivité spectrale. Parmi ceux-ci, le nitrure de gallium GaN ou le nitrure d'aluminium-gallium AIGaN possèdent de plus une affinité électronique dite « négative »: le niveau d'énergie des électrons dans la bande de conduction est supérieur à celui du niveau dit du vide. En pratique, les électrons doivent passer la barrière de potentiel présente à la surface de la photocathode. On résout ce problème par un abaissement du niveau de la barrière obtenu par la métallisation de la couche en matériau semi-conducteur ou par une orientation adéquate des bandes de conduction.A photocathode is a material capable of converting light radiation into electrons by secondary emission. The photocathode may be a metal layer with a weak electronic extraction work. It can also be a layer of semiconductor material which has the advantage of presenting a better spectral selectivity. Among them, gallium nitride GaN or aluminum-gallium nitride AIGaN also have a so-called "negative" electronic affinity: the energy level of the electrons in the conduction band is greater than that of the so-called empty. In practice, the electrons must pass the potential barrier present on the surface of the photocathode. This problem is solved by lowering the level of the barrier obtained by the metallization of the semiconductor material layer or by an adequate orientation of the conduction bands.
Le matériau de la photocathode est caractérisé par une structure et des niveaux atomiques positionnés par rapport au niveau du vide. Le niveau de Fermi caractérise le niveau de remplissage des niveaux électroniques. Le champ électrique appliqué à l'échantillon vers l'extérieur définit la différence de potentiel entre les niveaux de Fermi de part et d'autre de l'interface. Il permet de dépasser la différence d'énergie existant entre l'énergie des électrons dans la bande de conduction et le niveau du vide au delà du matériau. Les électrons peuvent alors s'échapper avec une certaine énergie cinétique.The material of the photocathode is characterized by a structure and atomic levels positioned with respect to the vacuum level. The Fermi level characterizes the level of filling of the electronic levels. The electric field applied to the sample towards the outside defines the potential difference between the Fermi levels on either side of the interface. It makes it possible to exceed the energy difference existing between the energy of the electrons in the conduction band and the level of the vacuum beyond the material. The electrons can then escape with some kinetic energy.
La diminution du travail de sortie des électrons peut être réalisée en utilisant des dépôts à base de couches métalliques. Le matériau utilisé peut être du césium, un oxyde de césium ou du baryum. Les métaux permettent de fixer le niveau de Fermi en surface de manière à rapprocher le niveau d'énergie des électrons situés dans la bande de conduction du niveau du vide. Ceci permet de plus aux électrons d'être accélérés vers la surface. Des structures comportant une variation graduelle des pourcentages respectifs de matériaux semi-conducteurs de type AIGaN et InGaN permettent d'accentuer cette accélération.The reduction of the electron output work can be achieved by using deposits based on metal layers. The material used may be cesium, cesium oxide or barium. Metals are used to set the Fermi level at the surface to bring the energy level closer to the electrons in the vacuum level conduction band. This further allows the electrons to be accelerated to the surface. Structures comprising a gradual variation of the respective percentages of semiconductor materials of AIGaN and InGaN type make it possible to accentuate this acceleration.
Dans les couches métalliques permettant de diminuer le travail de sortie des électrons photo émis, ceux ci sont fournis par le métal lui même. Il est donc avantageux de remplacer le métal par un semi-conducteur préférentiellement de type p dans lequel les électrons pouvant être émis sont ceux qui succèdent à l'absorption d'un photon d'énergie supérieure au « gap », c'est-à-dire à l'énergie séparant la bande de valence de la bande de conduction. On obtient ainsi une sélectivité spectrale. A titre d'exemple, on peut utiliser des semi-conducteurs à gap direct comme l'arséniure d'indium- gallium ou InGaAs pour le proche infrarouge ou le nitrure d'aluminium- gallium AIGaN pour le rayonnement ultraviolet.In metal layers to reduce the output work of emitted photo electrons, these are provided by the metal itself. It is therefore advantageous to replace the metal with a preferentially p-type semiconductor in which the electrons that can be emitted are those which succeed the absorption of a photon of energy greater than the "gap", that is to say the energy separating the valence band from the conduction band. This gives a spectral selectivity. By way of example, direct gap semiconductors such as indium arsenide can be used. gallium or InGaAs for near infrared or aluminum gallium nitride AIGaN for ultraviolet radiation.
Un dispositif complet de détection du rayonnement ultraviolet comprend généralement une photocathode et un dispositif d'amplification électronique introduisant un gain dans la chaîne de détection. La technologie traditionnelle est basée sur l'emploi de photocathodes et de galettes d'amplification et de multiplication électronique, technologie dite « MCP » pour « Multi Channel Plate ». Elle est illustrée en figure 2. Elle comprend une photocathode d'émission 1 et une galette de micro-canaux 10 (dessin de gauche de la figure 2). Les micro-canaux 10 amplifient les électrons primaires e" émis par la photocathode 1 sous l'effet d'un rayonnement photonique « hv », chaque électron primaire e" donnant plusieurs électrons secondaires chaque fois qu'il heurte la paroi 1 1 d'un micro-canal comme montré sur le dessin de droite de la figure 2. Le flux électronique est finalement appliqué à un écran phosphorescent dont l'image est ensuite transférée à un capteur de type « CCD » par l'intermédiaire d'un adaptateur à fibre optique encore appelé « taper ». Sa fonction est d'adapter la dimension de l'image à celle d'un imageur classique de type « CCD » ou « CMOS». D'autres solutions à base de serpentins à lignes à retard permettent une analyse temporelle du signal détecté avec une résolution temporelle de quelques nanosecondes.A complete ultraviolet light detection device generally comprises a photocathode and an electronic amplification device introducing a gain into the detection chain. The traditional technology is based on the use of photocathodes and wafers of amplification and electronic multiplication, so-called "MCP" technology for "Multi Channel Plate". It is illustrated in FIG. 2. It comprises a transmission photocathode 1 and a microchannel slab 10 (drawing on the left of FIG. 2). The micro-channels 10 amplify the primary electrons e " emitted by the photocathode 1 under the effect of a photon radiation" hv ", each primary electron e " giving several secondary electrons each time it hits the wall 1 1 of a micro-channel as shown in the drawing on the right of Figure 2. The electronic flux is finally applied to a phosphorescent screen whose image is then transferred to a sensor type "CCD" via an adapter to optical fiber also called "tap". Its function is to adapt the dimension of the image to that of a conventional imager of "CCD" or "CMOS" type. Other solutions based on delay line coils allow temporal analysis of the detected signal with a time resolution of a few nanoseconds.
Une troisième voie met en œuvre le bombardement électronique direct des électrons secondaires issus de la photocathode sur des capteurs de type « CCD » et/ou « CMOS » amincis pour être sensibles aux rayonnements pénétrants peu dans le matériau, tel le rayonnement ultraviolet ou les rayonnements électroniques. Ces dispositifs optimisés pour la détection de l'ultraviolet permettent de collecter les porteurs créés sur la face arrière du silicium en diminuant l'épaisseur du substrat jusqu'à une dizaine de microns. Ces dispositifs pour lesquels l'absorption a lieu dans les premières dizaines de nanomètres, permettent également de collecter des électrons absorbés sur des épaisseurs analogues. Ils sont connus sous les appellations « EBCCD » signifiant « Electron Bombarbed Charge-Coupled Device » ou « EBCMOS» signifiant « Electron Bombarbed Complementary Metal-Oxide Semiconductor». Une telle structure est représentée en figure 3. Elle comprend essentiellement une photocathode 1 , une matrice d'amplification électronique 2 et un dispositif matriciel 3 de type CMOS ou CCD. Un CMOS ou un CCD est un composant monolithique. On trouvera une description plus précise de structures de ce type dans l'article du Jet Propulsion Laboratory (Morrissey et al, A novel low-voltage Electron- Bombarded CCD Readout, SPIE 2006).A third channel implements the direct electron bombardment of secondary electrons from the photocathode on "CCD" and / or "CMOS" type sensors thinned to be sensitive to little penetrating radiation in the material, such as ultraviolet radiation or radiation. e. These optimized devices for ultraviolet detection make it possible to collect the carriers created on the back face of the silicon by reducing the thickness of the substrate to about ten microns. These devices for which the absorption takes place in the first tens of nanometers, also allow to collect absorbed electrons on similar thicknesses. They are known by the names "EBCCD" meaning "Electron Bombarbed Charge-Coupled Device" or "EBCMOS" meaning "Electron Bombarbed Complementary Metal-Oxide Semiconductor". Such a structure is represented in FIG. It essentially comprises a photocathode 1, an electronic amplification matrix 2 and a matrix device 3 of the CMOS or CCD type. CMOS or CCD is a monolithic component. A more detailed description of such structures can be found in the Jet Propulsion Laboratory article (Morrissey et al, A Novel Low-Voltage Electron-Bombarded CCD Readout, SPIE 2006).
Dans les capteurs « EBCCD » ou « EBCMOS », deux modes de transduction existent selon que les photons ont une énergie supérieure ou inférieure au gap de la photocathode en AIGaN. Les photons d'énergie supérieure au gap génèrent des électrons accélérés à quelques kilovolts donnant chacun environ un millier de paires électron-trou dans les CCD ou les CMOS. Les photons visibles « hv' » d'énergie inférieure au gap passent à travers la photocathode en AIGaN, éclairent la membrane et donnent au mieux une paire électron-trou par photon. En effet, ces capteurs en silicium ne sont pas « solar-blind ». La dynamique entre le signal produit par le rayonnement ultraviolet et le rayonnement visible est alors au mieux d'un facteur mille, ce qui est peu compte-tenu du faible flux de rayonnement ultraviolet. Pour réduire ce problème et augmenter la dynamique, le dispositif selon l'invention comporte une matrice de détection « solar-blind » connectée à un multiplexeur en configuration « hybride CMOS », permettant de réduire considérablement l'effet des photons visibles.In the "EBCCD" or "EBCMOS" sensors, two transduction modes exist depending on whether the photons have an energy greater than or less than the gap in the AIGaN photocathode. Photons of energy greater than the gap generate electrons accelerated to a few kilovolts each giving about a thousand electron-hole pairs in CCD or CMOS. The visible photons "hv" with energy below the gap pass through the photocathode in AIGaN, illuminate the membrane and give at best an electron-hole pair per photon. Indeed, these silicon sensors are not "solar-blind". The dynamic between the signal produced by the ultraviolet radiation and the visible radiation is then at best a factor of one thousand, which is little considering the low ultraviolet radiation flux. To reduce this problem and increase the dynamic range, the device according to the invention comprises a "solar-blind" detection matrix connected to a multiplexer in "hybrid CMOS" configuration, making it possible to considerably reduce the effect of visible photons.
Plus précisément, l'invention a pour objet un dispositif de détection du rayonnement ultra-violet, de type « EBCMOS hybride» comportant une photocathode et un détecteur matriciel agencé de façon à détecter les électrons émis par la dite photocathode, ledit détecteur comportant une membrane collectrice desdits électrons, caractérisé en ce que ladite membrane est réalisée dans un matériau dit « solar-blind », c'est-à-dire dans un matériau dont l'absorption optique est quasiment nulle pour un rayonnement optique dont les longueurs d'onde sont inférieures ou égales àMore specifically, the subject of the invention is a device for detecting ultraviolet radiation of the "hybrid EBCMOS" type comprising a photocathode and a matrix detector arranged to detect the electrons emitted by said photocathode, said detector comprising a membrane collector of said electrons, characterized in that said membrane is made of a material called "solar-blind", that is to say in a material whose optical absorption is almost zero for optical radiation whose wavelengths are less than or equal to
280 nanomètres.280 nanometers.
Plus particulièrement, le matériau de ladite membrane peut être le diamant ou au moins un des matériaux de ladite membrane est un matériau semiconducteur appartenant à la famille (Ga, AI)N. Avantageusement, la membrane est une structure de type diode « Schottky » comportant au moins trois couches d'AIGaN, la première couche comportant une première concentration en aluminium, la troisième couche comportant une seconde concentration en aluminium inférieure à la première concentration, la première couche étant séparée de la troisième couche par une seconde couche dont la concentration en aluminium varie continûment de la valeur de la concentration de la première couche à la valeur de la concentration de la troisième couche, la seconde couche étant dopée de type n. Dans une autre variante, la membrane est une structure de typeMore particularly, the material of said membrane may be diamond or at least one of the materials of said membrane is a semiconductor material belonging to the (Ga, Al) N family. Advantageously, the membrane is a "Schottky" diode type structure comprising at least three layers of AlGaN, the first layer having a first concentration of aluminum, the third layer having a second concentration of aluminum less than the first concentration, the first layer being separated from the third layer by a second layer whose aluminum concentration continuously varies from the value of the concentration of the first layer to the value of the concentration of the third layer, the second layer being doped n-type. In another variant, the membrane is a structure of the type
P. I. N. comportant au moins quatre couches d'AIGaN, la première couche comportant une première concentration en aluminium, la troisième couche comportant une seconde concentration en aluminium inférieure à la première concentration, la première couche étant séparée de la troisième couche par une seconde couche dont la concentration en aluminium varie continûment de la valeur de la concentration de la première couche à la valeur de la concentration de la troisième couche, la seconde couche étant dopée de type n, la quatrième couche étant dopée de type p.PIN comprising at least four layers of AIGaN, the first layer having a first concentration of aluminum, the third layer having a second aluminum concentration lower than the first concentration, the first layer being separated from the third layer by a second layer whose The concentration of aluminum varies continuously from the value of the concentration of the first layer to the value of the concentration of the third layer, the second layer being doped of type n, the fourth layer being p-doped.
Plus précisément, la différence de concentration en aluminium entre la première et la troisième couche peut être de l'ordre de 20%.More precisely, the difference in aluminum concentration between the first and third layers may be of the order of 20%.
La photocathode peut être une structure comportant au moins une couche de matériau semi-conducteur appartenant à la famille (Ga1AI)N dans ce cas, la configuration cristallographique de la maille hexagonale de la molécule de GaN est soit (0001) , soit (oooï), soit (lïoo), soit (ll2θ).The photocathode may be a structure comprising at least one layer of semiconductor material belonging to the (Ga 1 Al) N family. In this case, the crystallographic configuration of the hexagonal mesh of the GaN molecule is either (0001) or ( oooï), either (loo) or (l2o).
L'invention sera mieux comprise et d'autres avantages apparaîtront à la lecture de la description qui va suivre donnée à titre non limitatif et grâce aux figures annexées parmi lesquelles :The invention will be better understood and other advantages will become apparent on reading the description which follows given by way of non-limiting example and by virtue of the appended figures among which:
La figure 1 déjà décrite représente la variation de l'éclairement solaire dans la bande spectrale comprise entre 260 et 400 nanomètres ;Figure 1 already described represents the variation of solar irradiance in the spectral band between 260 and 400 nanometers;
La figure 2 représente un dispositif selon l'art antérieur à technologie dite « MCP » ;Figure 2 shows a device according to the prior art technology called "MCP";
La figure 3 représente une vue en coupe d'un dispositif selon l'art antérieur à technologie dite « EBCMOS ou EBCCD » ; La figure 4 représente une vue en coupe d'un dispositif selon l'invention à technologie dite « EBCMOS hybride » ;Figure 3 shows a sectional view of a device according to the prior art technology called "EBCMOS or EBCCD"; FIG. 4 represents a cross-sectional view of a device according to the invention with "hybrid EBCMOS"technology;
La figure 5 représente une vue en coupe d'une première réalisation de la membrane du dispositif selon l'invention ; La figure 6 représente une vue en coupe d'une seconde réalisation de la membrane du dispositif selon l'invention.FIG. 5 represents a sectional view of a first embodiment of the membrane of the device according to the invention; FIG. 6 represents a sectional view of a second embodiment of the membrane of the device according to the invention.
La différence entre un dispositif « EBCCD » ou « EBCMOS » selon l'art antérieur et un dispositif « EBCMOS hybride » selon l'invention réside essentiellement dans la mise en place d'une nouvelle membrane de type « solar blind », c'est-à-dire dans un matériau dont l'absorption optique est quasiment nulle pour un rayonnement optique dont les longueurs d'onde sont inférieures ou égales à 280 nanomètres. On dit encore que sa longueur d'onde de coupure est inférieure ou égale à 280 nanomètres. On entend par longueur d'onde de coupure la longueur d'onde à partir de laquelle la transmission résiduelle diminue brutalement (sur quelques nanomètres) de plusieurs ordres de grandeur. Dans ce cas, comme illustré en figure 4, les photons « hv' » non absorbés dans la photocathode 1 passent à travers celle-ci puis sont absorbés par la membrane 2 sans produire d'électrons. Il peut, par exemple, s'agir d'une membrane réalisée en matériau de la famille (Ga1AI)N ou en diamant. La raideur du front de coupure tel que doit la présenter un filtre « solar blind » dans l'ultraviolet n'est pas requise dans la mesure où il n'y a pas nécessité à transmettre l'ultraviolet. Les électrons utiles issus de la photocathode et provenant du rayonnement ultraviolet sont amplifiés par la membrane 2 et sont recueillis par les contacts 31. Chaque contact électrique primaire 31 est relié à un dispositif matriciel de multiplexage ou « multiplexor » 3 par l'intermédiaire de billes de connexion 32, les contacts sont isolés entre eux par un diélectrique d'isolation 33. La couche 22 disposée en avant de la membrane est une couche sacrificielle permettant de diminuer le taux de dislocations et d'améliorer la qualité cristalline du matériau. Des protections électriques du « multiplexor » 34 complètent le dispositif.The difference between an "EBCCD" or "EBCMOS" device according to the prior art and a "hybrid EBCMOS" device according to the invention lies essentially in the introduction of a new "solar blind" type membrane, which is that is to say in a material whose optical absorption is almost zero for optical radiation whose wavelengths are less than or equal to 280 nanometers. It is still said that its cut-off wavelength is less than or equal to 280 nanometers. Cut-off wavelength is the wavelength from which the residual transmission decreases abruptly (over a few nanometers) by several orders of magnitude. In this case, as illustrated in FIG. 4, the photons "hv" not absorbed in the photocathode 1 pass therethrough and then are absorbed by the membrane 2 without producing electrons. It may, for example, be a membrane made of family material (Ga 1 Al) N or diamond. The stiffness of the cutoff front such as must be presented a "solar blind" filter in the ultraviolet is not required to the extent that there is no need to transmit the ultraviolet. The useful electrons coming from the photocathode and originating from the ultraviolet radiation are amplified by the membrane 2 and are collected by the contacts 31. Each primary electrical contact 31 is connected to a multiplexing or "multiplexer" 3 matrix device via beads. connection 32, the contacts are isolated from each other by an insulating dielectric 33. The layer 22 disposed in front of the membrane is a sacrificial layer to reduce the dislocation rate and improve the crystalline quality of the material. Electrical protections of the "multiplexor" 34 complete the device.
La membrane peut être réalisée en diamant. Le diamant présente une mobilité importante qui permet de collecter les électrons absorbés en face arrière tout en préservant un substrat d'une centaine de microns. En revanche, le gap important du diamant (5.5eV), diminue le nombre de paires électrons-trous formées par les porteurs accélérés.The membrane can be made of diamond. The diamond has a high mobility which makes it possible to collect the electrons absorbed by back side while preserving a substrate of a hundred microns. On the other hand, the large diamond gap (5.5eV) decreases the number of electron-hole pairs formed by the accelerated carriers.
Lorsque la membrane est réalisée en AIGaN, elle peut être une structure de type diode « Schottky », une structure de type diode « MSM » ou une structure de type « P. I. N ».When the membrane is made of AIGaN, it may be a "Schottky" diode type structure, a "MSM" type diode structure or a "P. I. N" type structure.
Dans le cas d'une structure « Schottky » telle qu'illustré en figure 5, la structure comporte au moins trois couches d'AIGaN disposée sur un substrat 20, la première couche 21 comportant une première concentration en aluminium, la troisième couche 23 comportant une seconde concentration en aluminium inférieure à la première concentration, la première couche 21 étant séparée de la troisième couche par une seconde couche 22 dont la concentration en aluminium varie continûment de la valeur de la concentration de la première couche à la valeur de la concentration de la troisième couche, la seconde couche étant dopée de type n. A titre d'exemple, l'épaisseur de la première couche peut être de 1 micron, l'épaisseur de la seconde couche peut être de 0.2 micron et celle de la troisième couche de 0.6 micron, le dopage de la seconde couche peut être fait avec une concentration de dopants égale ou supérieure à 2.109 particules. cm"3. La première couche peut être retirée partiellement avec le substrat pour faciliter la collection de porteurs.In the case of a "Schottky" structure as illustrated in FIG. 5, the structure comprises at least three layers of AIGaN disposed on a substrate 20, the first layer 21 having a first concentration of aluminum, the third layer 23 comprising a second aluminum concentration lower than the first concentration, the first layer 21 being separated from the third layer by a second layer 22 whose aluminum concentration varies continuously from the value of the concentration of the first layer to the value of the concentration of the third layer, the second layer being n-type doped. For example, the thickness of the first layer can be 1 micron, the thickness of the second layer can be 0.2 micron and that of the third layer of 0.6 micron, the doping of the second layer can be done with a dopant concentration equal to or greater than 2.10 9 particles. cm "3. The first layer may be removed partly with the substrate to facilitate the carrier collection.
Une variante de ce dispositif consiste en une structure Métal - Semiconducteur - Métal (MSM) composée de deux contacts Schottky sous polarisation où seules les couches 21 et 22 sont présentes.A variant of this device consists of a Metal - Semiconductor - Metal (MSM) structure composed of two polarized Schottky contacts where only layers 21 and 22 are present.
Dans une autre variante illustrée en figure 6, la membrane est une structure de type P. I. N. comportant au moins quatre couches d'AIGaN disposées sur un substrat 20, la première couche 21 comportant une première concentration en aluminium, la troisième couche 23 comportant une seconde concentration en aluminium inférieure à la première concentration, la première couche 21 étant séparée de la troisième couche 23 par une seconde couche 22 dont la concentration en aluminium varie continûment de la valeur de la concentration de la première couche à la valeur de la concentration de la troisième couche, la seconde couche étant dopée de type n, la quatrième couche 24 étant dopée de type p. A titre d'exemple, l'épaisseur de la première couche peut être de 1 micron, l'épaisseur de la seconde couche peut être de 0.2 micron, l'épaisseur de la troisième couche de 0.6 micron et celle de la quatrième couche de 0.2 micron. Le dopage des seconde et quatrième couches peut être fait avec une concentration de dopants égal ou supérieur à 2.109 particules. cm"3.In another variant illustrated in FIG. 6, the membrane is a PIN type structure comprising at least four AIGaN layers disposed on a substrate 20, the first layer 21 having a first concentration of aluminum, the third layer 23 comprising a second concentration aluminum lower than the first concentration, the first layer 21 being separated from the third layer 23 by a second layer 22 whose aluminum concentration varies continuously from the value of the concentration of the first layer to the value of the concentration of the third layer, the second layer being doped with type n, the fourth layer 24 being p-type doped. For example, the thickness of the first layer may be 1 micron, the thickness of the second layer may be 0.2 micron, the thickness of the third layer 0.6 micron and that of the fourth layer 0.2 micron. Doping of the second and fourth layers can be done with a dopant concentration equal to or greater than 2.10 9 particles. cm "3 .
Quelque soit la variante de réalisation retenue, au cours du procédé de réalisation, la première couche peut être retirée partiellement avec le substrat pour faciliter la collection de porteurs. Dans tous les cas, la différence de concentration en aluminium entre la première et la troisième couche peut être de l'ordre de 20%. Par exemple, la concentration peut varier entre 0 et 25% ou entre 45 et 65%.Whatever the embodiment variant selected, during the production process, the first layer may be partially removed with the substrate to facilitate the collection of carriers. In all cases, the difference in aluminum concentration between the first and the third layer may be of the order of 20%. For example, the concentration may vary between 0 and 25% or between 45 and 65%.
Concernant la photocathode 1 , on peut faciliter l'émission d'électrons en utilisant la polarité azote du matériau la plus appropriée à l'accélération des porteurs vers la surface tout en bénéficiant d'un travail de sortie faible. Typiquement, la photocathode peut être une structure comportant au moins une couche de matériau semi-conducteur appartenant à la famille (Ga,AI)N. Elle remplace le dipôle formé entre les atomes de césium et la couche de semi-conducteur. Elle fournit des électrons seulement après absorption de photons contrairement aux couches césurées qui sont quant à elles métalliques. Le dopage p ou un caractère isolant est alors requis.With regard to the photocathode 1, it is possible to facilitate the emission of electrons by using the nitrogen polarity of the material most suitable for accelerating the carriers towards the surface while benefiting from a low output work. Typically, the photocathode may be a structure comprising at least one layer of semiconductor material belonging to the (Ga, Al) N family. It replaces the dipole formed between the cesium atoms and the semiconductor layer. It provides electrons only after photon absorption, unlike the meshes that are metallic. P-doping or an insulative character is then required.
Dans ce cas, la configuration cristallographique de la maille hexagonale de la molécule de GaN est soit (0001) , soit (oooï), soit (lToo), soit (ll2θ) en utilisant les notations classiques de la cristallographie. In this case, the crystallographic configuration of the hexagonal mesh of the GaN molecule is either (0001) or (oooï) or (lToo) or (ll2θ) using the conventional notations of crystallography.

Claims

REVENDICATIONS
1. Dispositif de détection du rayonnement ultra-violet, de type « EBCMOS hybride » comportant une photocathode (1 ) et un détecteur matriciel (3) agencé de façon à détecter les électrons émis par la dite photocathode, ledit détecteur comportant une membrane (2) collectrice desdits électrons, caractérisé en ce que ladite membrane est réalisée dans un matériau dit « solar-blind », c'est-à-dire dans un matériau dont l'absorption optique est quasiment nulle pour un rayonnement optique dont les longueurs d'onde sont inférieures ou égales à 280 nanomètres.1. Device for detecting ultraviolet radiation, of the "hybrid EBCMOS" type comprising a photocathode (1) and a matrix detector (3) arranged to detect the electrons emitted by said photocathode, said detector comprising a membrane (2 ) collector said electrons, characterized in that said membrane is made of a material called "solar-blind", that is to say in a material whose optical absorption is almost zero for optical radiation whose lengths of wave are less than or equal to 280 nanometers.
2. Dispositif selon la revendication 1 , caractérisé en ce que le matériau de ladite membrane est le diamant.2. Device according to claim 1, characterized in that the material of said membrane is diamond.
3. Dispositif selon la revendication 1 , caractérisé en ce qu'au moins un des matériaux de ladite membrane est un matériau semiconducteur appartenant à la famille (Ga, AI)N.3. Device according to claim 1, characterized in that at least one of said membrane material is a semiconductor material belonging to the family (Ga, Al) N.
4. Dispositif selon la revendication 3, caractérisé en ce que la membrane est une structure de type diode « Schottky » comportant au moins trois couches d'AIGaN, la première couche (21 ) comportant une première concentration en aluminium, la troisième couche (23) comportant une seconde concentration en aluminium inférieure à la première concentration, la première couche étant séparée de la troisième couche par une seconde couche (22) dont la concentration en aluminium varie continûment de la valeur de la concentration de la première couche à la valeur de la concentration de la troisième couche, la seconde couche (22) étant dopée de type n.4. Device according to claim 3, characterized in that the membrane is a "Schottky" diode type structure comprising at least three layers of AIGaN, the first layer (21) having a first concentration of aluminum, the third layer (23). ) having a second aluminum concentration lower than the first concentration, the first layer being separated from the third layer by a second layer (22) whose aluminum concentration varies continuously from the value of the concentration of the first layer to the value of the concentration of the third layer, the second layer (22) being n-doped.
5. Dispositif selon la revendication 3, caractérisé en ce que la membrane est une structure de type Métal - Semiconducteur - Métal composée de deux contacts Schottky sous polarisation comportant au moins deux couches d'AIGaN, la première couche (21 ) comportant une première concentration en aluminium, la troisième couche (23) comportant une seconde concentration en aluminium inférieure à la première concentration.5. Device according to claim 3, characterized in that the membrane is a structure of metal-semiconductor-metal type composed of two polarized Schottky contacts comprising at least two layers of AIGaN, the first layer (21) comprising a first aluminum concentration, the third layer (23) having a second aluminum concentration lower than the first concentration.
6. Dispositif selon la revendication 3, caractérisé en ce que la membrane est une structure de type P. I. N. comportant au moins quatre couches d'AIGaN, la première couche (21 ) comportant une première concentration en aluminium, la troisième couche (23) comportant une seconde concentration en aluminium inférieure à la première concentration, la première couche étant séparée de la troisième couche par une seconde couche (22) dont la concentration en aluminium varie continûment de la valeur de la concentration de la première couche à la valeur de la concentration de la troisième couche, la seconde couche étant dopée de type n, la quatrième couche étant dopée de type p..6. Device according to claim 3, characterized in that the membrane is a PIN type structure comprising at least four layers of AIGaN, the first layer (21) having a first concentration of aluminum, the third layer (23) having a second concentration of aluminum lower than the first concentration, the first layer being separated from the third layer by a second layer (22) whose aluminum concentration varies continuously from the value of the concentration of the first layer to the value of the concentration of the third layer, the second layer being n-doped, the fourth layer being p-type doped.
7. Dispositif selon l'une des revendications 4, 5 ou 6, caractérisé en ce que la différence de concentration en aluminium entre la première couche (21 ) et la troisième couche (23) est de l'ordre de 20%.7. Device according to one of claims 4, 5 or 6, characterized in that the difference in aluminum concentration between the first layer (21) and the third layer (23) is of the order of 20%.
8. Dispositif selon la revendication 1 , caractérisé en ce que la photocathode (1 ) est une structure comportant au moins une couche de matériau semiconducteur appartenant à la famille (Ga,AI)N.8. Device according to claim 1, characterized in that the photocathode (1) is a structure comprising at least one layer of semiconductor material belonging to the family (Ga, Al) N.
9. Dispositif selon la revendication 8, caractérisé en ce que la configuration cristallographique de la maille hexagonale de la molécule de GaN est soit (OOOl) , soit (θθθï), soit (lToo), soit (ll2θ). 9. Device according to claim 8, characterized in that the crystallographic configuration of the hexagonal mesh of the GaN molecule is either (OOOl) or (θθθi), or (lToo), or (112θ).
PCT/EP2009/053007 2008-03-18 2009-03-13 Device for detecting ultraviolet radiation of the hybrid ebcmos type, comprising a membrane insensitive to solar radiation WO2009115466A1 (en)

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FR0801484A FR2929001B1 (en) 2008-03-18 2008-03-18 HYBRID EBCMOS-TYPE ULTRAVIOLET RADIATION DETECTION DEVICE COMPRISING A SOLAR-RADIATION-INSENSITIVE MEMBRANE

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