CN111293013B - A field emission cold cathode structure and its manufacturing method - Google Patents
A field emission cold cathode structure and its manufacturing method Download PDFInfo
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- CN111293013B CN111293013B CN202010227464.1A CN202010227464A CN111293013B CN 111293013 B CN111293013 B CN 111293013B CN 202010227464 A CN202010227464 A CN 202010227464A CN 111293013 B CN111293013 B CN 111293013B
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- 238000004519 manufacturing process Methods 0.000 title claims description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 43
- 239000002041 carbon nanotube Substances 0.000 claims abstract description 42
- 229910021393 carbon nanotube Inorganic materials 0.000 claims abstract description 42
- 239000000758 substrate Substances 0.000 claims abstract description 22
- 239000000463 material Substances 0.000 claims abstract description 6
- 238000005530 etching Methods 0.000 claims description 4
- 239000002238 carbon nanotube film Substances 0.000 claims description 3
- 238000010329 laser etching Methods 0.000 claims 1
- 238000000034 method Methods 0.000 description 5
- 230000005684 electric field Effects 0.000 description 4
- 239000002086 nanomaterial Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 2
- MGRWKWACZDFZJT-UHFFFAOYSA-N molybdenum tungsten Chemical compound [Mo].[W] MGRWKWACZDFZJT-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000000609 electron-beam lithography Methods 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000002070 nanowire Substances 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000002230 thermal chemical vapour deposition Methods 0.000 description 1
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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
- H01J1/30—Cold cathodes, e.g. field-emissive cathode
- H01J1/304—Field-emissive cathodes
- H01J1/3042—Field-emissive cathodes microengineered, e.g. Spindt-type
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/02—Manufacture of electrodes or electrode systems
- H01J9/022—Manufacture of electrodes or electrode systems of cold cathodes
- H01J9/025—Manufacture of electrodes or electrode systems of cold cathodes of field 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
- H01J2201/30434—Nanotubes
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- 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
- H01J2201/30469—Carbon nanotubes (CNTs)
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- Cold Cathode And The Manufacture (AREA)
Abstract
本发明公开了一种场发射冷阴极结构，包括冷阴极、阴极衬底，将所述冷阴极的正面设置成长方形结构，且所述冷阴极垂直设置在阴极衬底上；所述的冷阴极的长度与宽度之比大于或等于100，将冷阴极作为发射体，其发射端面为线型一维结构；所述的冷阴极的高度与宽度之比大于或等于50，使得所述的冷阴极呈二维线型结构，所述的冷阴极的宽度小于10微米，所述的冷阴极由碳纳米管材料制成。本实施例所述的冷阴极结构可具备了获得大电流高电流密度的场发射能力，是实现场发射冷阴极器件应用的一种优选结构，可以满足特定器件的电子源性能需求。
The invention discloses a field emission cold cathode structure, comprising a cold cathode and a cathode substrate, the front side of the cold cathode is arranged in a rectangular structure, and the cold cathode is vertically arranged on the cathode substrate; the cold cathode The ratio of the length to the width is greater than or equal to 100, the cold cathode is used as the emitter, and its emitting end face is a linear one-dimensional structure; the ratio of the height to the width of the cold cathode is greater than or equal to 50, so that the cold cathode In a two-dimensional linear structure, the width of the cold cathode is less than 10 microns, and the cold cathode is made of carbon nanotube material. The cold cathode structure described in this embodiment can have the field emission capability of obtaining large current and high current density, which is a preferred structure for realizing the application of field emission cold cathode devices, and can meet the electron source performance requirements of specific devices.
Description
Technical Field
The invention relates to the technical field of vacuum electronic devices, in particular to a field emission cold cathode structure and a manufacturing method thereof.
Background
Field emission is a method of generating electrons in a vacuum by lowering the height and width of the barrier of the emitter vacuum surface by applying an external electric field, thereby achieving electron emission. An electron emission structure based on the physical principle of field emission is called a cold cathode. Compared with the existing commercial hot cathode, the field emission cold cathode has the characteristics of normal-temperature work, quick start-up time, low power consumption, large current density and the like, and has application prospects in the field of electronic information, such as microwave and terahertz wave vacuum electronic devices, X-ray tubes, ion neutralizers, electron beam lithography and the like.
New generation vacuum electronic devices, X-ray tubes, etc. require miniaturized, integratable, high performance electron sources, and cold cathodes meet such requirements. Facing the requirements of a large-current high-current-density electron source, the carbon nano tube, the tungsten-molybdenum nano pointed cone and other nano materials show excellent large-current field emission characteristics. These nanomaterials are used as cold cathodes and have been nano-lattice structures or other structures as emitters. The nano lattice structure is characterized in that a vertical carbon nano tube is used as an emission point, each carbon nano tube is separated by a certain distance to form a row-column lattice, the electric field shielding effect can be reduced, and the problems of poor stability, easy breakdown and poor lattice emission uniformity exist.
Although the carbon nanotubes have excellent field emission characteristics, the excellent characteristics of the carbon nanotubes for cold cathode applications are limited by the structure of the emitter and cannot be fully utilized. The emitter structure is a key factor for restricting excellent field emission characteristics, and the search for a more excellent carbon nanotube emitter structure is an important problem for realizing the application of a cold cathode device.
Disclosure of Invention
The invention provides a field emission cold cathode structure and a manufacturing method thereof, aiming at solving the problem that the field emission characteristic of a carbon nano tube is limited by the structure of an emitter.
In order to achieve the purpose of the invention, the technical scheme is as follows: a field emission cold cathode structure comprises a cold cathode and a cathode substrate, wherein the front surface of the cold cathode is arranged into a cuboid structure, and the cold cathode is vertically arranged on the cathode substrate; the ratio of the length to the width of the cold cathode is more than or equal to 100, the cold cathode is used as an emitter, and the emitting end face of the cold cathode is of a linear one-dimensional structure; the ratio of the height to the width of the cold cathode is greater than or equal to 50, so that the cold cathode is in a two-dimensional linear structure, the width of the cold cathode is less than 10 micrometers, and the cold cathode is made of carbon nanotube materials.
Preferably, the carbon nanotubes are vertical carbon nanotubes, that is, the cold cathode is formed by densely arranging vertical carbon nanotubes, and each vertical carbon nanotube is perpendicular to the cathode substrate.
Further, the diameter of the vertical carbon nanotube is less than or equal to 5 nm.
Based on the field emission cold cathode structure, the invention also provides a manufacturing method of the field emission cold cathode structure, and the manufacturing method comprises the following steps:
s1: growing a vertical carbon nanotube film on a cathode substrate;
s2: vertically etching the vertical carbon nano tube outside the linear structure area on the cathode substrate by adopting high-power laser;
s3: the vertical carbon nanotubes which are not etched by the laser form a two-dimensional linear field emission cold cathode emission structure of the carbon nanotubes, and the cold cathode is vertical to the cathode substrate.
The invention has the following beneficial effects:
the carbon nano tube is adopted to construct the cold cathode with the cuboid structure, the length-width ratio of which is greater than or equal to 100, and the cold cathode is used as an emitter, the emitting end face of the cold cathode is of a linear one-dimensional structure, the influence of the electric field shielding effect among dense nano structures on the emitting characteristics of the emitter is reduced, the field emitting address is effectively increased, and the field emitting stability is improved. Therefore, the two-dimensional linear cold cathode structure can have the field emission capability of obtaining large current and high current density, is an optimal structure for realizing the application of a field emission cold cathode device, and can meet the performance requirements of an electron source of a specific device.
Drawings
Fig. 1 is a schematic diagram of a field emission cold cathode structure according to example 1, in which 1 represents a cold cathode structure and 2 represents a cathode substrate.
Fig. 2 is a topographical view of a cold cathode structure achieved in example 1, in which fig. (a) is a side view in the length-height direction of the structure, fig. (b) is a top view in the length-width direction of the structure, fig. (c) is a side view in the width-height direction of the structure, and fig. (d) is a partially enlarged view of fig. (a).
Fig. 3 is a field emission address image of the cold cathode structure described in example 1.
FIG. 4 is experimental data of example 1 using the two-pole structure test method, in which (a) is a field emission current-voltage relationship curve and (b) is an F-N curve.
Detailed Description
The invention is described in detail below with reference to the drawings and the detailed description.
Example 1
As shown in fig. 1, a field emission cold cathode structure includes a cold cathode, a cathode substrate, wherein the front surface of the cold cathode is configured as a rectangular structure, and the cold cathode is vertically disposed on the cathode substrate; the ratio of the length to the width of the cold cathode is more than or equal to 100, the cold cathode is used as an emitter, and the emitting end face of the cold cathode is of a linear one-dimensional structure; the ratio of the height to the width of the cold cathode is greater than or equal to 50, so that the cold cathode is in a two-dimensional linear structure, the width of the cold cathode is less than 10 micrometers, and the cold cathode is made of carbon nanotube materials.
In a specific embodiment, the actually fabricated field emission cold cathode structure, as shown in fig. 2(a) (b) (c), has a height of 500 μm, a length of 1mm, a width of 1 μm, a ratio of the length to the width of 1000, and a height to width ratio of 500, such that the cold cathode structure is in a two-dimensional line shape and is a high wall body with a microstructure as viewed from the side. A partial enlargement of the field emission cold cathode structure shows that the structure is composed of a close-packed array of vertical carbon nanotubes, each of which is perpendicular to the cathode substrate, and a single vertical carbon nanotube has a diameter of about 3nm, as shown in fig. 2 (d). The carbon nano tubes on the linear emission end surface are densely arranged in a single dimension, so that the problem of poor stability of a single vertical carbon nano tube is solved;
the field emission cathode structure described in this embodiment has the characteristics that the emission end face is a linear one-dimensional structure, so that the influence of the electric field shielding effect between the dense nanostructures on the emission characteristics of the emitter is reduced, and the field emission address is effectively increased, as shown in fig. 3. The cold cathode structure of the high wall body can improve the field emission enhancement factor; the two-dimensional linear cold cathode structure is composed of the dense vertical carbon nano tubes, and the integral failure of the emitter caused by the breakdown of a single vertical carbon nano tube can be avoided. Therefore, the structure can obtain high current capability by using low-voltage driving field emission and has higher field emission stability.
Based on the field emission cold cathode structure, the present embodiment further provides a manufacturing method of the field emission cold cathode structure, where the manufacturing method includes the following steps:
s1: and (3) growing a vertical carbon nanotube film with the height of about 500 mu m on the cathode substrate by adopting a thermal chemical vapor deposition method without limitation. Wherein the cathode substrate is made of silicon material.
S2: using continuous high-power laser with the power of 1.5W, the spot diameter of 0.1mm and the wavelength of 450nm to control the laser beam to be vertical to the surface of the vertical carbon nanotube array, and etching the vertical carbon nanotube outside the linear structure on the cathode substrate by a scanning method;
s3: the vertical carbon nanotubes left without being etched by the laser constitute a two-dimensional linear field emission cold cathode emission structure of the carbon nanotubes, and the cold cathode is perpendicular to the cathode substrate, so that the cold cathode of the two-dimensional linear structure of the vertical carbon nanotubes shown in fig. 2 is realized.
The method for etching the carbon nanotube by using the laser has the advantages that the microscopic morphology and the curvature radius of the top end of the carbon nanotube cold cathode can be modified to improve the field emission characteristic and the stability, which cannot be achieved by using a patterned direct growth method.
Based on the field emission cold cathode structure of this embodiment, this embodiment adopts a two-pole structure testing method to perform a field emission characteristic test on the cold cathode structure, and the vacuum degree of the vacuum chamber for the test<5×10-6Pa, the anode is a metal flat plate, the cathode is the field emission cold cathode structure described in this embodiment, and the distance between the anode and the cathode is 0.2 mm. The field emission current-voltage relation curve and the F-N curve obtained by testing are shown in FIG. 4, the field emission current is 1mA when the voltage is applied to 450V, and the F-N curve is linear, which shows that the two-dimensional linear cold cathode structure of the carbon nano tube conforms to the field emission rule.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. One of ordinary skill in the art will appreciate that other variations of the present invention are possible. The cathode takes other shapes, such as circular arc, sawtooth shape, irregular curved surface and the like. The material is made of other materials, such as graphene, zinc oxide nanowires, tungsten molybdenum nanowires and the like. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
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| EP1904670B1 (en) * | 2005-06-28 | 2011-09-28 | The Board of Regents of the University of Oklahoma | Methods for growing and harvesting carbon nanotubes |
| CN1897205B (en) * | 2005-07-15 | 2010-07-28 | 清华大学 | Carbon nanotube array emitting element and manufacturing method thereof |
| CN101652382B (en) * | 2006-12-04 | 2016-04-06 | 特拉维夫大学拉莫特有限公司 | The formation of organic nanostructure array |
| KR100892366B1 (en) * | 2006-12-26 | 2009-04-10 | 한국과학기술원 | Carbon nanotube field emission emitter and its manufacturing method |
| CN101290857B (en) * | 2007-04-20 | 2011-06-22 | 清华大学 | Field emission cathode and its preparation method |
| CN101748380A (en) * | 2008-12-15 | 2010-06-23 | 索尼株式会社 | Method for preparing carbon nano tube films, carbon nano tube films and carbon nano tube elements |
| US9058954B2 (en) * | 2012-02-20 | 2015-06-16 | Georgia Tech Research Corporation | Carbon nanotube field emission devices and methods of making same |
| KR102040150B1 (en) * | 2013-09-02 | 2019-11-04 | 삼성전자주식회사 | Field emission element and method of manufacturing emitter of field emission element |
| US10598575B2 (en) * | 2015-07-17 | 2020-03-24 | The Penn State Research Foundation | Sizable tunable enrichment platform for capturing nano particles in a fluid |
| CN205473958U (en) * | 2016-03-21 | 2016-08-17 | 中国计量学院 | E type carbon nanotube electronic gun evaporation source |
| CN106191802A (en) * | 2016-07-08 | 2016-12-07 | 重庆启越涌阳微电子科技发展有限公司 | The preparation method that selective growth vertical graphite is dilute |
| KR101982289B1 (en) * | 2017-09-21 | 2019-05-24 | 고려대학교 산학협력단 | Carbon nanotube elelctron emitter, method for manufacturing the same and x-ray source using the same |
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