EP1930931A1 - Elektronenemissionsquelle und Feldemissionsanzeigevorrichtung - Google Patents

Elektronenemissionsquelle und Feldemissionsanzeigevorrichtung Download PDF

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Publication number
EP1930931A1
EP1930931A1 EP06256237A EP06256237A EP1930931A1 EP 1930931 A1 EP1930931 A1 EP 1930931A1 EP 06256237 A EP06256237 A EP 06256237A EP 06256237 A EP06256237 A EP 06256237A EP 1930931 A1 EP1930931 A1 EP 1930931A1
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EP
European Patent Office
Prior art keywords
electron emission
film structures
layer
emission source
substrate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP06256237A
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English (en)
French (fr)
Inventor
Jason Lo
Jian-Min Jeng
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tatung Co Ltd
Original Assignee
Tatung Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tatung Co Ltd filed Critical Tatung Co Ltd
Priority to EP06256237A priority Critical patent/EP1930931A1/de
Publication of EP1930931A1 publication Critical patent/EP1930931A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/04—Cathodes
    • 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
    • H01J31/10—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes
    • H01J31/12—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen
    • H01J31/123—Flat display tubes
    • 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
    • H01J2201/30446—Field emission cathodes characterised by the emitter material
    • H01J2201/30453—Carbon types
    • H01J2201/30457—Diamond
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2209/00—Apparatus and processes for manufacture of discharge tubes
    • H01J2209/02—Manufacture of cathodes
    • H01J2209/022—Cold cathodes
    • H01J2209/0223—Field emission cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2329/00—Electron emission display panels, e.g. field emission display panels

Definitions

  • the present invention relates to an electron emission source, more particularly to a field emission display with an electron emission source.
  • Display devices have become particularly important in our daily lives. Aside from using PC systems or browsing the Internet, display devices are also used in TVs, mobile phones, Personal Digital Assistant (PDAs), and digital cameras for visual presentation of images and text. Compared to traditional cathode ray tubes (CRTs), newer flat panel displays have the advantages of being lightweight and compact, and are less harmful to human health.
  • PDAs Personal Digital Assistant
  • CTRs cathode ray tubes
  • FEDs field emission displays
  • LCDs Liquid Crystal Displays
  • the FEDs operate similarly to cathode ray tubes under vacuum environments with a pressure of less than 10 -6 torr, such that an electric field is used to pull out the electrons on the tip of the cathode, and under the acceleration by the positive voltage of an anode plate, the electrons impinge on the phosphor powder on the anode plate so as to create luminescence.
  • FEDs control the variation of the voltage difference applied between a gate and the cathode, and cause each electron-emitter to emit electrons at a prescribed time.
  • the work function and geometric construction of the field emitter cathode are ideally as small as possible.
  • current research on the material for the electron-emitter of FEDs is primarily focused on the type of carbon with chemical stability, electrical conductivity, or low electron affinity. More specifically, the preferred carbon material includes amorphous carbon films, diamond films, diamond-like carbon films, and carbon nanotubes.
  • carbon nanotubes Due to the structural nature of high aspect ratio, carbon nanotubes have a characteristic of low threshold voltage and high current emission density, i.e. a good field enhancement factor, thus making carbon nanotubes a popular field emission material.
  • carbon nanotubes are not without shortcomings.
  • the nano-scale nature in structure makes difficulty in distributing the carbon nanotubes evenly in the electron-emitter paste, resulting in uneven current distribution and shorter operating lifetime.
  • a tendency of enlarging surface area of nanotubes structure gives rise to its instability.
  • Diamond-like carbon is primarily composed of amorphous carbon with SP 3 three-dimensional and SP 2 planar structures.
  • the SP 3 structure has a lower electron affinity and a stronger mechanical property, and the SP 2 structure has a better conductive property; therefore, the DLC formed with these two structures achieves the benefits of both low electron affinity and better conductive property.
  • DLC has stable material properties that are favorable for the subsequent manufacturing processing of elements in becoming a good electron emission material.
  • the object of the present invention is to provide an electron emission source and a field emission display, wherein the electron emission layer used for the electron emission source is a DLC composition that includes a plurality of micro-scale film structures.
  • the film structures in the DLC composition of the present invention have heights in micro-scale dimensions, and thickness in nano-scale dimensions.
  • the DLC composition with plural micro-scale film structures of the invention has a high aspect ratio, giving rise to a good field enhancement factor favorable for electron emission and becoming a good electron emission source.
  • radio frequency sputtering is used in the invention to deposit the DLC film, allowing a large area to be manufactured so as to reduce the time for preparation and the cost for manufacture.
  • the invention achieves the object by providing an electron emission source, including a substrate and an electron emission layer formed on the surface of the substrate.
  • the electron emission layer includes a composition of DLC with a plurality of micro-scale film structures.
  • the invention achieves the object by further providing another aspect of an electron emission source that includes a substrate, a conductive layer formed on the surface of the substrate, and an electron emission layer formed on the surface of the conduction layer.
  • the electron emission layer includes a composition of DLC with a plurality of micro-scale film structures.
  • the invention achieves the object by further providing a field emission display that includes an upper substrate having a phosphor layer and an anode layer, and a lower substrate having an electron emission layer and a cathode layer.
  • the electron emission layer is closely adjacent to, and electrically connected with the cathode layer.
  • the electron emission layer includes a composition of DLC with a plurality of micro-scale film structures.
  • the film structures of the DLC layer are formed on the surface of the substrate as a paste.
  • the lateral height of the film structures is between 0.5 ⁇ m and 4.0 ⁇ m, and preferably is between 0.9 ⁇ m and 2.0 ⁇ m.
  • the thickness of the film structures is preferably between 0.005 ⁇ m and 0.1 ⁇ m, and more preferably is between 0.005 ⁇ m and 0.05 ⁇ m.
  • the film structures of the DLC film layer of the invention can have a micro-scale height and a nano-scale thickness, giving rise to a high aspect ratio favorable for electron emission.
  • the substrate material is preferably, but not limited to, semiconductor material or glass material.
  • the invention further selectively includes a conduction layer on the surface of the substrate, disposed between the substrate and the DLC film layer.
  • the conduction layer can be of any conductive material, preferably of Indium Tin Oxide (ITO), zinc oxide, Zinc Tin Oxide (ZTO), or metal material, such as silver epoxy.
  • the surface of the glass substrate is coated with a conductive layer to allow the film structures of the DLC film layer to be formed on the conduction layer surface more easily.
  • the conductive layer provides a current to the film structures of the DLC film layer, which then can act as an electron emission source.
  • the substrate is constituted of a semiconductor material. Since the substrate material is conductive by nature, the film structures of the DLC film layer can be directly formed on the surface of the substrate so as to become an electron emission source.
  • the film structures of the DLC film layer of the electron emission source are preferably, but not limited to, long-strip film structures or curved film structures.
  • the primary feature of the film structures is the high aspect ratio, which allows the DLC film layer of the invention to have a great film enhancement factor ideal for a good electron emission source.
  • the electron emission source of the present invention can be applied in any technology fields requiring electron emission, preferably in cold cathode emitters such as field emission elements, field emission displays, or flat panel light sources.
  • the electron emission layer composition preferably further includes an adhesive material, for better combining the DLC material and the conductive material to form an evenly mixed composition.
  • the adhesive material is preferably, but not limited to, ethyl cellulose.
  • the field emission display of the invention further includes a gate electrode layer disposed between the upper substrate and the lower substrate.
  • the gate electrode layer can be any gate electrodes traditionally used in field emission displays, and is preferably a ring gate electrode having a plurality of hollow holes.
  • the gate electrode layer allows every electron-emitter to accurately emit electrons at prescribed times.
  • the upper substrate of the field emission display of the present invention can further include a photo-mask layer.
  • the photo-mask layer can be disposed closely to the phosphor layer to mask off leaking light and to increase picture contrast.
  • the micro-scaled film structures of the DLC are more easily distributable in the composition, allowing manufacture of a field emitter that can emit electrons evenly.
  • the field emission display of the invention can easily accomplish the making of an electron emission layer so as to satisfy the need of a field emission flat panel display requiring a large-scale glass substrate.
  • the micro-scaled film structures of the DLC used by the invention require a relatively lower temperature for growth process, and can be directly grown on the substrate surface, and thus are favorable for application in fabrication.
  • the film structures of the DLC of the invention have a high aspect ratio, hence a high field enhancement factor, making the invention applicable in a cold cathode emitting source such as field emission elements, field emission displays, or flat panel light sources.
  • FIG. 1 shows a schematic view of a sputtering reaction chamber 100 for making the DLC film layer according to this embodiment.
  • the reaction chamber 100 includes a heater 10 and lamp 1 for heating a substrate 111, a loading platform 11 for supporting the substrate 111, a power supply 13 for applying voltage on a target material 12, and a plurality of gas supplying units A, B, and C for supplying reactant gas.
  • the number of the gas supplying units can be increased or decreased depending on the gas conditions required for the process.
  • the substrate 111 is a semiconductor silicon wafer.
  • a vacuum pump device 14 removes air from the reaction chamber 100 to leave a pressure of under 1x10 -5 torr, and lamp 1 the heater 10 heats the substrate 111 up to a temperature of 500°C.
  • the gases required for reaction are supplied by the gas supplying units A, B, C into the reaction chamber 100, and a mass flow controller (not shown) is provided for controlling the flow rates of the gases into the reaction chamber 100.
  • the gas-supplying units A, B, and C in the embodiment are gas-supplying sources containing argon, methane, and hydrogen, respectively. Whether the gases are introduced into the reaction chamber 100 is determined by the manufacturing conditions, and the flow of the gases is regulated by gas supplying valves a1, b1 and c1. In this embodiment, the gases introduced into the reaction chamber 100 are argon, methane and hydrogen, with a ratio of 2:1:1, as indicated in table 1. Table 1 Argon Methane Hydrogen Embodiment 1 10 5 5 5
  • the internal pressure is controlled to 9x10 -3 torr.
  • the surrounding pressure for a sputtering reaction is not to be limited, but can be adjustable upon manufacturing needs.
  • the graphite target material 12 is pre-sputtered for 30 minutes with 200W of RF power so as to remove possible pollutants from the surface of the target material 12 as the shutter 15 is closed.
  • the shutter 15 is opened and the surface of substrate 111 undergoes sputtering for 70 minutes to grow a DLC layer on substrate surface.
  • FIG. 2 is an SEM (Scanning Electron Microscope) photo of the DLC powder obtained in the first embodiment.
  • a composition with 8.7% DLC powder, 8.7% glass powder and 82.6% silver powder is evenly mixed together, with addition of ethyl cellulose as adhesives, to form a paste for use as an electron emission source material.
  • a glass substrate with a conductive silver paste thereon is taken as a cathode plate.
  • the above-mentioned electron emission source paste is coated on the silver paste surface so as to complete the cathode plate structure.
  • an anode plate is structurally equivalent to the one in the first embodiment.
  • FIG. 3 is schematic view illustrating the diode configuration used for testing field emission effects according to the present embodiment of the invention.
  • a test film 3 of DLC film paste layer 31 is used as a cathode plate 301, and a substrate 32 with a luminance layer 33 is used as an anode plate 302.
  • the luminance layer 33 is a phosphor layer
  • the ITO glass substrate 32 is a glass substrate having an ITO layer that acts as the anode layer (not shown).
  • a cathode plate 301 is emplaced in a container 35, and above which is covered with an anode plate 302.
  • the container 35 is then placed inside a vacuum chamber and the pressure is reduced to below 1x10 -6 torr.
  • a voltage is applied between the two electrode plates 301 and 302 for measuring the magnitude of the current produced by the electron emission source of the cathode plate 301.
  • FIG. 4 shows the plot of the result of the field emissions test performed on the electron emission source formed by mixing DLC powder into a paste composition.
  • a sintered electron emission source paste presents more superior field emission effects than an unsintered electron emission source paste. Namely, when the same voltage potential is applied between the two electrode plates, the electron emission source with a sintered substrate surface has a higher current flow.
  • FIG. 5 is schematic illustrating a triode type field emission testing apparatus used in the present embodiment of the invention.
  • the electron emission source is same as the one used in the second embodiment. Namely, the same mixing composition is used to obtain the electron emission source paste.
  • the triode-type field emission testing apparatus of this embodiment has an additional gate electrode layer 74 on a cathode plate 701 and an insulating layer 73 for insulating the cathode layer 71 from the gate layer 74.
  • the cathode layer 71, the gate electrode layer 74, and an anode layer 76 form together a triode configuration.
  • the cathode layer 71 in this embodiment is molybdenum/titanium metal; the gate electrode layer 74 is molybdenum, and the anode layer 76 is ITO.
  • the electron emission source paste of this embodiment is coated over the surface of the cathode layer 71, and a voltage potential is applied between the two electrode plates 701 and 702 for testing field emission effects. Meanwhile, a voltage difference is applied between the cathode layer 71 and the gate electrode layer 74 so as to enhance the electron emission effects of the electron emission source.
  • FIG. 6 shows the plot of the field emission effects of the present embodiment.
  • the electric field applied between the two electrode plates increases, the current density of the electron emission source also increases.
  • the voltage difference applied between the cathode layer 71 and the gate electrode layer 74 is incrementally increased from 5V to 35V, the field emission effects are greatly increased.
  • this applied voltage difference has its limitations. That is, if the voltage difference is greater than the load that the elements can sustain, such as by applying a voltage difference of 40V and 50V between the cathode layer 71 and the gate electrode layer 74, then most electrons will be attracted towards the gate electrode, causing adverse effects.
  • the DLC structure manufactured according to the present invention aids to increase the field emission effects.
  • the DLC not only can be evenly distributed in the electron emission source material, but also the film structure formed on the substrate can be used as the electron emission source.
  • the field emission effects achieved by the two different methods both bear a low starting voltage, a quality favorable for a good cathode electron emission source.
  • the field emission display in this embodiment is similar to the triode-type field emission testing apparatus described in the third embodiment. Aside from an additional phosphor layer and a photo-mask layer on the anode plate, the structure of a lower substrate in this embodiment is the same as that of the third embodiment.
  • the electron emission source of the field emission display in this embodiment is an electron emission source paste formed by mixing DLC powder, glass powder, silver powder and ethylene cellulose, and coated on the surface of a cathode layer having conductive silver paste, which are then sintered to form an electron emission layer.
  • the electron emission source when an electric field is applied between the two electrode plates of the field emission display, where a voltage difference is simultaneously applied between the gate electrode player and the cathode layer, the electron emission source emits electrons to impinge on the phosphor layer of the anode plate so as to cause luminescence.
  • the field emission display in this embodiment is structurally similar to the one shown in the fourth embodiment.
  • the surface of the lower substrate includes a molybdenum/titanium metal layer that acts as a cathode layer.
  • the material of the substrate used in this embodiment is glass.
  • the surface of the cathode layer in this embodiment includes a patterned insulating layer and gate electrode layer to partially expose the surface of the cathode.
  • the insulating layer in this embodiment is disposed between the cathode layer and the gate electrode layer to provide electrical insulation.
  • the above-mentioned lower substrate structure is placed in a sputtering reaction chamber, and undergone a sputtering reaction as described in the first embodiment so as to grow an electron emission layer having a DLC film layer on the exposed cathode surface. Finally, the DLC film layer deposited on the surface of the gate electrode is removed so as to obtain the lower substrate of the field emission display of the present embodiment.
  • the structural characteristic of the DLC film layer in this embodiment is similar to that of the first embodiment.
  • a DLC with micro-scale film structures can be manufactured, that have a high aspect ratio favorable in use as electron emission source material applied in a cold cathode emitting source, such as field emission elements, field emission displays, or flat panel light sources.

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  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Cold Cathode And The Manufacture (AREA)
EP06256237A 2006-12-07 2006-12-07 Elektronenemissionsquelle und Feldemissionsanzeigevorrichtung Withdrawn EP1930931A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP06256237A EP1930931A1 (de) 2006-12-07 2006-12-07 Elektronenemissionsquelle und Feldemissionsanzeigevorrichtung

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP06256237A EP1930931A1 (de) 2006-12-07 2006-12-07 Elektronenemissionsquelle und Feldemissionsanzeigevorrichtung

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EP1930931A1 true EP1930931A1 (de) 2008-06-11

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109613064A (zh) * 2018-11-16 2019-04-12 兰州空间技术物理研究所 一种真空系统内电极间距可调的场致发射测试装置及方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995022169A1 (en) * 1994-02-14 1995-08-17 E.I. Du Pont De Nemours And Company Diamond fiber field emitters
WO1997045854A1 (en) * 1996-05-31 1997-12-04 Minnesota Mining And Manufacturing Company Field emission device having nanostructured emitters
US6448709B1 (en) * 1999-09-15 2002-09-10 Industrial Technology Research Institute Field emission display panel having diode structure and method for fabricating
WO2005001871A2 (en) * 2003-06-11 2005-01-06 Chien-Min Sung Amorphous diamond materials and associated methods for the use and manufacture thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995022169A1 (en) * 1994-02-14 1995-08-17 E.I. Du Pont De Nemours And Company Diamond fiber field emitters
WO1997045854A1 (en) * 1996-05-31 1997-12-04 Minnesota Mining And Manufacturing Company Field emission device having nanostructured emitters
US6448709B1 (en) * 1999-09-15 2002-09-10 Industrial Technology Research Institute Field emission display panel having diode structure and method for fabricating
WO2005001871A2 (en) * 2003-06-11 2005-01-06 Chien-Min Sung Amorphous diamond materials and associated methods for the use and manufacture thereof

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
C.J.TORNG,J.M.SIVERTSEN,J.H.JUDY,C.CHANG: "Structure and bonding studies of the C:N thin films produced by rf sputtering method", J. MATER. RES., vol. 5, no. 11, November 1990 (1990-11-01), pages 2490 - 2496, XP002432689 *
LIU D ET AL: "Conducting atomic force microscopy for nanoscale electron emissions from various diamond-like carbon films", APPLIED SURFACE SCIENCE, ELSEVIER, AMSTERDAM, NL, vol. 249, no. 1-4, 15 August 2005 (2005-08-15), pages 315 - 321, XP004965329, ISSN: 0169-4332 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109613064A (zh) * 2018-11-16 2019-04-12 兰州空间技术物理研究所 一种真空系统内电极间距可调的场致发射测试装置及方法

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