EP3267463A2 - Elektronische vakuumröhre mit einer planaren kathode auf der basis von nanoröhren oder nanodrähten - Google Patents

Elektronische vakuumröhre mit einer planaren kathode auf der basis von nanoröhren oder nanodrähten Download PDF

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EP3267463A2
EP3267463A2 EP17178583.5A EP17178583A EP3267463A2 EP 3267463 A2 EP3267463 A2 EP 3267463A2 EP 17178583 A EP17178583 A EP 17178583A EP 3267463 A2 EP3267463 A2 EP 3267463A2
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Prior art keywords
nanotube
nanowire
cathode
tube according
elements
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EP17178583.5A
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English (en)
French (fr)
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EP3267463A3 (de
Inventor
Jean-Paul Mazellier
Lucie SABAUT
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Thales SA
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Thales SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/30—Cold cathodes, e.g. field-emissive cathode
    • H01J1/304—Field-emissive cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/15—Cathodes heated directly by an electric current
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/30—Cold cathodes, e.g. field-emissive cathode
    • H01J1/312—Cold cathodes, e.g. field-emissive cathode having an electric field perpendicular to the surface, e.g. tunnel-effect cathodes of metal-insulator-metal [MIM] type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J21/00—Vacuum tubes
    • H01J21/02—Tubes with a single discharge path
    • H01J21/06—Tubes with a single discharge path having electrostatic control means only
    • H01J21/10—Tubes with a single discharge path having electrostatic control means only with one or more immovable internal control electrodes, e.g. triode, pentode, octode
    • H01J21/105—Tubes with a single discharge path having electrostatic control means only with one or more immovable internal control electrodes, e.g. triode, pentode, octode with microengineered cathode and control electrodes, e.g. Spindt-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02—Electrodes; Magnetic control means; Screens
    • H01J23/04—Cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/06—Cathodes
    • H01J35/065—Field emission, photo emission or secondary emission cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00—Electrodes common to discharge tubes
    • H01J2201/30—Cold cathodes
    • H01J2201/304—Field emission cathodes
    • H01J2201/30403—Field emission cathodes characterised by the emitter shape
    • H01J2201/30423—Microengineered edge emitters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2201/00—Electrodes common to discharge tubes
    • H01J2201/30—Cold cathodes
    • H01J2201/304—Field emission cathodes
    • H01J2201/30403—Field emission cathodes characterised by the emitter shape
    • H01J2201/30434—Nanotubes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/06—Cathode assembly
    • H01J2235/068—Multi-cathode assembly

Definitions

  • the invention relates to the field of vacuum electronic tubes, which find applications for example for the production of X-ray tubes or traveling wave tubes (TOP). More particularly, the invention relates to vacuum electronic tubes whose cathode is based on nanotubes or nanowires.
  • Cold cathodes are based on an electron emission by emission of field: an intense electric field (some V / nm) applied on a material allows a curvature of the barrier of energy sufficient to allow the electrons to transit towards the vacuum by tunnel effect . To obtain fields as intense in a macroscopic way is impossible.
  • the vertical spike cathodes use field emission combined with the peak effect.
  • a geometry widely used and developed in the literature consists of producing vertical points P (with a high aspect ratio) on a substrate as illustrated figure 2 .
  • peak effect the field at the top of the transmitter can be of the desired order.
  • This field is generated by the electrostatic disturbance represented by the tip in a homogeneous field. In this configuration, a homogeneous external field E0 is applied. It is the variation of this field which makes it possible to control the level of field at the top of the emitters and thus the level of emitted current corresponding.
  • the first cathodes with integrated grid (“gated cathode”), called Spindt tips, were developed in the 70's, and are illustrated figure 3 .
  • Their principle is based on the use of a conductive tip 20 surrounded by a control gate 25.
  • the apex is on the plane of the grid. It is the difference of potential between the points and the grid which makes it possible to modulate the level of electric field at the apex of the peaks (and thus the emitted current).
  • These structures are known for their very high sensitivity to tip / grid alignment and for electrical insulation problems between the two elements.
  • More recently point emitters have been made from carbon nanotubes or CNT (for "Carbon NanoTube” in English) arranged vertically perpendicular to the substrate.
  • An integrated grid cathode “Gated Cathode” CNT carbon nanotubes is also described for example in the patent application No. PCT / EP2015 / 080990 and illustrated figure 4 .
  • a grid G is arranged around each VACNT (for "Vertically Aligned CNT").
  • Field emission results from the electric field at the surface of a typically metallic material. This field is directly related to the gradient of the applied electric potential field.
  • the potential field results from the combination of the influences of the external field and the potential of the nanotube only. But both are linked.
  • the potential field at the level of the nanotubes results from the combination of the influences of the external electric field, the potential of the nanotube (as above), but also the potential induced by the gate which is independent of the two. other.
  • the potential induced by the gate which is independent of the two. other.
  • the field amplification factor associated with each transmitter is strongly related to its height and the radius of curvature of its tip. Dispersions in these two parameters induce amplification factor dispersions. But the tunnel effect is an exponential law involving this amplification factor: thus, considering a cohort of emitters, a fraction (which can be relatively small, of the order of a percent or less) only actually participates in the electronic broadcast.
  • a first example is illustrated figure 5 : a tip type transmitter Pp, ZnO nanowire type, is parallel to the substrate. One of its ends is connected to an electrode (Cath cathode) and a counter electrode (Anode A) makes it possible to generate the equivalent of the homogeneous field E0 in the case of vertical structures. The show always appears at the apex of the tip.
  • FIG. 6 A second example operating according to the same principle, comprising a gate G and a doped polysilicon tip Pp, is illustrated figure 6 .
  • a vacuum tube it is sought to use the electron beam "far" from the cathode.
  • the anode is in close proximity to the emissive element (in order to limit the voltages to be applied), so that the beam travels a very short distance before being intercepted by the anode. . It can not be used further in the vacuum tube.
  • Thermionic cathodes use the thermionic effect to emit electrons. This effect consists in emitting electrons by heating. For this we polarize the two electrodes arranged at the ends of a filament. The application of a potential difference between the two ends generates a current in the filament, which heats by the Joule effect. When it reaches a certain temperature (typically 1000 degrees Celsius) electrons are emitted. Indeed the mere fact of heating allows some electrons to have a higher thermal energy than the metal-vacuum barrier: thus they are spontaneously extracted to the vacuum. There are pellet-shaped cathodes (of the order of a millimeter) with an electric filament placed underneath to heat the material, which will then emit electrons.
  • the thermionic cathodes make it possible to provide strong currents over long periods in relatively average voids (up to 10 -6 mbar, for example). But their emission is difficult to switch quickly (at the scale of a fraction of GHz for example), the size of the source is fixed and their temperature limits the compactness of the tubes where they are integrated.
  • An object of the present invention is to overcome the aforementioned drawbacks by proposing an electronic vacuum tube having a planar cathode based nanotubes or nanowires, to overcome a number of limitations related to the use of emitting points vertical, while using the tunnel effect or the thermionic effect or a combination of both.
  • the present invention relates to a vacuum electron tube comprising at least one electron emitting cathode and at least one anode disposed in a vacuum chamber, the cathode having a planar structure comprising a substrate comprising a conductive material, a plurality of nanotube or nanowire elements electrically isolated from the substrate, the longitudinal axis of said nanotube or nanowire elements being substantially parallel to the plane of the substrate, and at least one first connector electrically connected to at least one nanotube or nanowire element so as to be able to apply to the nanowire element or nanotube a first electrical potential.
  • the nanotube or nanowire elements are substantially parallel to each other.
  • the first connector comprises a substantially planar contact element disposed on an insulating layer and connected to a first end of the nanotube or nanowire element.
  • the cathode further comprises a first control means connected to the first connector and to the substrate, and configured to apply a bias voltage between the substrate and the nanotube element so that the nanotube or nanowire element emits electrons by its surface by tunnel effect.
  • the bias voltage is between 100 V and 1000 V.
  • the nanotube or nanowire elements have a radius of between 1 nm and 100 nm.
  • the cathode comprises a second electrical connector electrically connected to at least one nanotube or nanowire element so as to be able to apply a second electric potential to the nanotube or nanowire element.
  • the first and second connectors respectively comprise a first and a second substantially planar contact element disposed on a layer and respectively connected to a first and second ends of said nanotube element or nanowire.
  • the cathode comprises at least one nanotube or nanowire element connected simultaneously to the first connector and to the second connector.
  • the cathode further comprises means for heating the nanotube or nanowire element.
  • the cathode comprises a second control means connected to the first and second connectors and configured to apply a heating voltage to said nanotube or nanowire element via the first and second electric potential, so as to generate a electric current in said nanotube element or nanowire, so that the nanotube or nanowire element emits electrons by its surface by thermoionic effect.
  • the heating voltage is between 0.1 V and 10 V.
  • the nanotube or nanowire elements are partially buried in an insulating burial layer.
  • the cathode is divided into a plurality of zones, the nanotube elements or nanowires of each zone being connected to a different first electrical connector, so that the bias voltages applied to each zone are independent and reconfigurable.
  • the nanotube or nanowire elements are conductive.
  • the nanotube or nanowire elements are semiconductors and in which the bias voltage is greater than a threshold voltage, the nanowire or nanotube element then constituting a channel of a MOS type capacitor, so as to generate free carriers in the nanowire or nanotube element.
  • the cathode further comprises a light source configured to illuminate the nanotube or nanowire element so as to generate free carriers in said nanowire or nanotube element by photogeneration.
  • the vacuum electronic tube 70 according to the invention is illustrated figure 7 , which describes a profile view and a perspective view of the cathode C of the device.
  • the vacuum electronic tube according to the invention is typically an X-ray tube or a TOP.
  • the vacuum electronic tube 70 comprises at least one cathode C emitting electrons and at least one anode A disposed in a vacuum chamber E.
  • the specificity of the invention lies in the original structure of the cathode, the rest of the tube being dimensioned according to the state of the art.
  • the at least one cathode C of the tube 70 has a planar structure comprising a substrate Sb comprising a conductive material, that is to say having an electrical behavior close to a metal, and a plurality of electrically isolated NT nanotube or nanowire elements. of the substrate.
  • the insulation is carried out with an insulating layer Is deposited on the substrate, the nanotube elements or NT nanowires being arranged on the insulating layer Is.
  • planar structure is meant that the longitudinal axis of the nanotube or nanowire elements is substantially parallel to the plane of the insulating layer, as shown figure 7 .
  • Nanotubes and nanowires are known to those skilled in the art. Nanotubes and nanowires are elements whose diameter is less than 100 nanometers and their length is from 1 to several tens of microns. The nanotube is a predominantly hollow structure while the nanowire is a solid structure. The two types of nano-element are generally called NT and are compatible with a cathode of the vacuum tube according to the invention.
  • the substrate is doped silicon, doped silicon carbide, or any other compatible conductive material of the manufacture of the cathode.
  • the cathode further comprises at least a first connector CE1 electrically connected to at least one nanotube or nanowire element so as to be able to apply to the element NT a first electrical potential.
  • the first connector CE1 thus allows electrical access to NT elements. Due to the complexity of manufacturing technology, not all NT elements of the cathode are connected. In the following we do not We will only consider NT elements that are actually electrically connected to the CE1 connector.
  • the elements NT (connected) of the cathode C in operation emit electrons from its surface S.
  • a first variant is based on the tunnel effect
  • a second variant is based on the thermionic effect, the two variants being combinable, allowing increased electron emission.
  • planar structure of NT elements has many advantages. It makes it possible to produce the generic device illustrated figure 7 compatible use of the two aforementioned effects, separately or in combination.
  • the manufacture of the elements NT according to the invention is carried out from known technological bricks, and does not require growth of the PECVD (DC plasma) type, as in the case of vertical carbon nanotubes, which releases the constraints on the usable materials and potential designs significantly.
  • PECVD DC plasma
  • surface insulation which is not compatible with PECVD growth to date, which makes it possible to obtain a higher level of robustness compared to current "gated cathode” designs.
  • the nanotube elements or nanowire NT are substantially parallel to each other, and the average distance W between each element is controlled.
  • An average distance between NT elements of the order of the thickness of the insulation is preferred. Parallelism ensures a greater compactness of integration and therefore a greater number of active transmitters per unit area, which potentially increases the current emitted by the structure.
  • the first connector CE1 comprises a substantially planar contact element C1 arranged an insulating layer Is and connected to a first end E1 of the element NT.
  • the manufacture of the CE1 connector is facilitated.
  • the contact element C1 is typically metallic, of a standard material in microelectronics: aluminum, titanium, gold, tungsten, etc.).
  • NT nanoelements are isolated from the substrate by vacuum.
  • the insulating layer Is having been used during the manufacture of the nanotubes has been removed (sacrificial layer) under the nanotube portion, these being then attached to the substrate by the planar contact C1, in turn insulated from the substrate by the insulating layer Is.
  • the insulator is obtained for the planar contact C1 by a sacrificial physical layer Is and for the elements NT by the vacuum Vac.
  • the thermal insulation of NT is increased.
  • the emission area is increased, the lower half surface being able to participate in the emitted current (provided that the external field E0 makes it possible to recover the electrons emitted by this lower half-surface).
  • the cathode is configured to emit electrons via its surface S by tunnel effect.
  • the cathode C of the tube 70 comprises a first control means MC1 connected to the first connector CE1, biased to the voltage V1, and to the substrate Sb, and configured to apply a bias voltage V NW between the substrate and the nanotube element.
  • the potential difference V NW must be negative.
  • the substrate may for example be connected to the ground.
  • the front contact with the elements NT via CE1 is indeed electrically isolated from the conductive substrate Sb.
  • an insulating layer Is "thick" with a thickness h of between 100 nm and 10 ⁇ m is preferable.
  • the bias voltage V NW is therefore established between the elements NT and the substrate.
  • This polarization voltage and the combined external macroplast field E0 induce a surface field E S on the NT element.
  • the nanoelement / insulator / substrate system forms a capacity that allows the generation of a large number of negative charges that focus on the small surface S of the nanotube, as illustrated.
  • figure 9 which generates an intense electric field E S on the surface of the element NT, expressed by lines of fields 90 very narrow in the vicinity of S.
  • the electric field Es is inversely proportional to the radius r of the element NT.
  • the applied external macroscopic field E0 is basic necessary for the needs of the vacuum electron tube (in particular to direct the electrons emitted into the tube).
  • the extraction of electrons is carried out by tunnel effect, and the electrons are emitted radially in all directions.
  • the external field E0 causes the electrons to take a trajectory 100 generally perpendicular to the substrate, as illustrated figure 10 , and accelerates them.
  • the external field E0 contributes only marginally here to the extraction (see below).
  • the present invention has the following advantages.
  • the horizontal emitting elements NT have exactly the same height h, contrary to conventional approaches (typically +/- 1 ⁇ m on the vertical nanotubes, for typical heights of 5 to 10 ⁇ m), which in fact reduces the height of the emitters. considerably the problem on the dispersion of this parameter, which is solved extremely simply by the use of a homogeneous insulating layer Is made with conventional microelectronic means.
  • the radius of nanotubes it is possible to apply methods that are otherwise known for producing nanowires / nanotubes with small radius dispersions.
  • the nanomaterials thus produced can be selected by various methods to minimize the dispersion on the radius factor (impossible if we consider growth on substrate). A dispersion of radius of +/- 2 nm is typically achievable (against +/- 20 nm for VACNT).
  • the cathode C is such that when the bias voltage V NW is low or zero, the field effect is negligible: the vacuum tube 70 operates in "Normally off” mode, which is a desired safety element in some applications of medical X-ray tubes.
  • the peak effect of the nano planar elements according to the invention is realized in two dimensions, and the potential electronic emission areas are therefore much higher.
  • the surface is of the order of ⁇ r 2 ; while for a planar nanotube it is of the order of Lr (L length of the nanowire, r radius of the nanowire) for a neighboring emitter density.
  • Lr L length of the nanowire, r radius of the nanowire
  • the nanotube or NT nanowire elements have a radius r between 1 nm and 100 nm.
  • the first term is purely geometric, with typical values of 10 to 100.
  • the bias voltage V NW is typically between 100 V and 1000 V.
  • E0 is of the order of 0.01 V / nm and the term V NW / (h / ⁇ r ) of the order of 0.1 V / nm.
  • the term V NW / (h / ⁇ r ) is large before E0, and it is this first term which contributes to the first order to obtain the field Es.
  • E0 is not used for electron extraction, that is to say that there is independence between generation / extraction (via V NW ) and acceleration (via E0) of the electrons is a huge advantage for the X-ray tubes.
  • the emission current is changed.
  • the bias voltage which conditions the value of the emission current, not or little the external field E0. It is thus possible in an X-ray tube according to the invention to produce an identical emission current image for different energies.
  • the cathode C comprises a second electrical connector CE2 electrically connected to at least one nanotube element or nanowire NT so as to be able to apply to the nano-element a second electrical potential V2.
  • the cathode comprises at least one element NT connected simultaneously to the first connector CE1 and the second connector CE2. in order to make the cathode according to the invention compatible with the use of the thermionic effect (see below).
  • a different potential is applied to both ends of the nano-element, which, with a conductive substrate, is only possible with the presence of an insulator between the nanoelement and the substrate.
  • the cathode C comprises several nanotube elements or NT nanowires connected to the same first connector and / or the same second connector.
  • the connector CE2 comprises a planar contact element C2 (typically metallic, of a standard material in microelectronics: aluminum, titanium, gold, tungsten, etc.), disposed on an insulating layer Is and connected to a second end E2 of the NT element as illustrated figure 12 .
  • a series of elements of electrical contacts are interconnected.
  • the contacts are preferably locally parallel and placed at a distance L. Between the electrodes are NT nanowires / nanotubes so that at least one of their ends is connected to one of the electrical contacts.
  • the characteristic distance between two nanowires / nanotubes is denoted W.
  • the figure 12 corresponds to the embodiment with a physical insulating layer Is deposited on the substrate.
  • the figure 12 bis illustrates the embodiment for which the Is layer has been removed under the nanotubes, also illustrated figure 7bis , the isolation thereof being performed by the vacuum present under the NT nanotubes.
  • the distance W between the elements NT is substantially constant and controlled. Indeed, it is preferable to respect an average distance of the order of the insulator thickness, the constancy in the value of the distance W being the ideal case.
  • Each element NT has an emitting surface of the order of 7000nm 2 (useful emission of the half surface S). Emitter emission currents per emitter (of the order of 200 nA) are acceptable by nanowires / nanotubes.
  • the cathode C according to the invention emits electrons by thermionic effect, by heating the element NT.
  • the cathode C further comprises means for heating the nanotube element or NT nanowire.
  • the nanotube elements it is not necessary to dimension the NT elements specifically, there is no constraint on the height h of the insulating layer Is or on the radius r of the elements NT.
  • a low-output material should be used for the nano elements, such as tungsten or molybdenum.
  • a preferred way to heat the nanotube / nanowire is to pass a current therein. For this, at least one nanotube element or NT nanowire must be simultaneously connected to the first connector CE1 and the second connector CE2.
  • the heating means comprise a second control means MC2 configured to apply a heating voltage Vch to the nanotube element or NT nanowire via the first electrical potential V1 and the second electrical potential V2.
  • Vch V1 - V2
  • An electric current I is thus generated in the nanotube / nanowire element NT.
  • the two connectors CE1 and CE2 must be sufficiently spatially separated on the nanotube to allow the current to circulate.
  • V NW no bias voltage
  • the heating temperature Vch is between 0.1 V and 10 V.
  • the figure 15 illustrates a cathode C according to the invention configured to emit electrons by thermoionic effect and based on planar contacts C1 and C2 of the same nature as those described in FIGS. figures 12 and 12bis .
  • the electrical voltage applied via CE1 and CE2 (respectively by the recovery of C1 and C2 contacts) creates a current I in the nanotube / nanowire element NT. In this case the stream 1 flows from one end to the other of the NT nanotube.
  • the cathode according to the invention combines the two physical effects of electron emission, tunneling effect and thermionic effect, as illustrated on the principle figure 16 .
  • a bias voltage V NW between 100 V and 1000 V
  • a voltage Vch between 0.1 V and 10 V
  • the NT nanotube preferably has a radius r between 1 nm and 100 nm, to optimize the tunnel effect.
  • the figure 17 illustrates the combination of the two effects using two contacts planar C1 and C2. This results in greater electron emission than when the two physical effects are used in isolation.
  • heating the emissive element reduces the field to be applied to emit a given current which is useful for reducing the dimensions for example of the insulator.
  • the emitting elements are "hot", surface contamination problems are avoided (the elements are less easily adsorbed on the hot surfaces). This improves the stability of the emission.
  • the presence of an empty interface - insulator - nanowire / nanotube is likely to induce a local exacerbation of the field. Since this interface is "under" the nanowire, it is preferable to reduce this effect because it can lead to local electronic injection into the insulator and unwanted load effects.
  • the nanotube or NT nanowire elements are partially buried in an Isent burial insulating layer. A constant field level is thus obtained according to the periphery of the nanowire / nanotube.
  • the Isent layer is the insulating layer disposed on the substrate Sb.
  • the Isent layer consists of at least one additional layer deposited on the insulating layer Is.
  • this partial burial can cause an electronic emission in the insulator, which induces local loading effects "shielding" the action of the substrate.
  • the Isent burial layer is a multilayer consisting of a plurality of sub-layers. This controls the structure of the field lines better and limits unwanted exacerbation effects. In addition one can play on the permittivity / dielectric strength parameters of the different layers to optimize the voltages applicable in the structure.
  • the incorporation of a high permittivity material can significantly modify the effective height, and this aspect should be taken into account in the dimensioning of the thickness h of the layer Is.
  • the cathode C is divided into a plurality of zones Z, Z ', each zone comprising nanotube elements or nanowires connected to the same first electrical connector: for example the elements NT of the zone Z are connected to CE1 and the elements NT of the zone Z 'are connected to CE1', CE1 being different from CE1 '. It is then possible to apply bias voltages V NW and V NW 'to each zone that is independent of one another and reconfigurable. The program is thus "pixelated" by producing several electrically autonomous emission zones in order to spatially modulate the emission zone.
  • the figure 19 illustrates a cathode C comprising an emitting zone Z while a zone Z 'does not emit
  • the figure 20 illustrates a cathode C with the two zones Z and Z 'emitting.
  • the spatial modulation of the emission zone is carried out by juxtaposing several cathodes next to one another.
  • At least one planar contact C1 is common to two groups of nano-elements. This densifies the network of nano-elements.
  • the nanotubes / nanoelements NT are made of conducting material, such as carbon, doped ZnO, doped silicon, silver, copper, tungsten, etc.
  • the nanotube / nanowire elements are semiconductors, for example Si, SiGe or GaN, so as to induce the presence by field effect and / or by illumination, which makes it possible to have additional levers on the control of the electronic broadcast.
  • the nanowire element or nanotube then constitutes a channel with a capacity of MOS type. Bearer generation occurs when the bias voltage V NW is greater than a threshold voltage Vth.
  • the tube 70 further comprises a light source configured to illuminate the nanotube or nanowire element, the free carriers are then generated by photogeneration.
  • Nano-elements NT semiconductors can be used to generate electrons by tunnel effect and / or by thermoionic effect
  • the figure 22 shows a first method of manufacturing the cathode C according to the invention, of the "bottom up” type.
  • a nanowire / nanotube NT dispersion is produced on an insulating layer Is deposited on a conductive substrate Sb ("spay", “dip coating”, electrophoresis).
  • the key point is to have an average distance W between controllable nanowires / nanotubes.
  • the contacts are made by lift-off on the mat previously produced. It should be noted that the contacts can be made before the dispersion (preferably buried contacts so that the surface of the contact material is at the level of the surface of the insulator) to have only the dispersion to be achieved as a final embodiment step.
  • the figure 23 shows a second method of manufacturing the cathode C according to the invention, of the "top-down" type.
  • a thin layer (intended to be the emitting material) is deposited on an insulating layer Is, itself on a conductive substrate Sb.
  • An etching mask is made on this layer and the material is etched to leave only nanowires / nanotubes on the + insulator substrate, as shown figure 23a .
  • the contacts are made by lift-off on the carpet previously made, as illustrated figure 23b . Note that as before the contacts can be made before the dispersion (preferably buried contacts so that the surface of the contact material is at the level of the surface of the insulation) to have only the dispersion to achieve as a final step of realization

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  • Cold Cathode And The Manufacture (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Microwave Tubes (AREA)
  • Electron Sources, Ion Sources (AREA)
  • Carbon And Carbon Compounds (AREA)
EP17178583.5A 2016-07-07 2017-06-29 Elektronische vakuumröhre mit einer planaren kathode auf der basis von nanoröhren oder nanodrähten Pending EP3267463A3 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR1601057A FR3053830A1 (fr) 2016-07-07 2016-07-07 Tube electronique sous vide a cathode planaire a base de nanotubes ou nanofils

Publications (2)

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EP3267463A2 true EP3267463A2 (de) 2018-01-10
EP3267463A3 EP3267463A3 (de) 2018-04-04

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CN112002628B (zh) * 2020-08-28 2023-06-23 云南电网有限责任公司电力科学研究院 X射线管阴极单元及其制备方法

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TW201812824A (zh) 2018-04-01
JP6982994B2 (ja) 2021-12-17
CN107591299B (zh) 2021-07-27
AU2017204507A1 (en) 2018-01-25
FR3053830A1 (fr) 2018-01-12
TWI753924B (zh) 2022-02-01
CN107591299A (zh) 2018-01-16
EP3267463A3 (de) 2018-04-04
AU2017204507B2 (en) 2022-04-14
KR102458120B1 (ko) 2022-10-21
US10720298B2 (en) 2020-07-21
JP2018010869A (ja) 2018-01-18
US20180012723A1 (en) 2018-01-11

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