TWI353616B - Thermionic source - Google Patents

Description

1353616 IX. Description of the Invention: [Technical Field] The present invention relates to a source of hot electrons, and more particularly to a source of thermoelectrons based on carbon nanotubes. [Prior Art] Since the first discovery of carbon nanotubes by Ijima, a scientist in 1991, (see Helical microtubules 〇f graphitic carb〇n, Nature,

Sumio Iijima, v〇i 35 卩 ^ 56^99”), nano-materials represented by carbon nanotubes have attracted great attention due to their unique structure and properties. In the past 4 years, along with carbon nanotubes And the research of nano materials continues to deepen, and its broad application prospects are constantly emerging. For example, due to the unique electromagnetic, optical, mechanical, and chemical properties of carbon nanotubes, a large number of related electronic emission devices and senses Applications such as detectors, new optical materials, and soft ferromagnetic materials have been reported. In general, electron-emitting devices use a hot electron emitter or a cold electron emitter as an electron-emitting source, which is emitted from an electron-emitting device using a thermal electron emitter. The phenomenon of electrons is called the phenomenon of thermal electron emission. The thermal electron emission system uses heating to increase the kinetic energy of electrons in the emitter, so that the kinetic energy of a part of the electrons is large enough to escape the surface barrier of the emitter and escape from the body. The electrons emitted from the surface may be referred to as hot electrons, and the emitter emitting the hot electrons may be referred to as a thermal electron emitter. The electron source generally includes a thermal electron emitter, a first electrode and a second electrode. The thermal electron emitter is disposed between the first electrode and the second electrode and is opposite to the first electrode and the second electrode Electrical contact. The hot electron source further includes a substrate, the thermal electron emitter 13536.16 • in contact with the substrate 'in the process of heating the thermal electron emitter, the emitter material, by means of vacuum deposition, • substrate It conducts heat to conduct most of the heat of the thermal electron emitter into the atmosphere. It affects the thermal electron emission properties of the prepared hot electron source. Usually, a metal, a boride material or an oxide material is used as the thermal electron emitter. Materials: The hot electron source is generally divided into two types: direct heat type and inter-heat type. The direct heat type uses metal as the hot electron emitter material, and the metal is made into a strip or a very fine wire. Between the first electrode and the second electrode, an electric current is applied between the first electrode and the second electrode, and a current flowing through the metal generates heat to make the metal The electrons of the part escape outside the body. The intercalation type is directly coated with a boride material or an oxide material as a thermoelectric conductive material or sprayed onto a heater; the heater is fixed to the above by welding or the like. Between the first electrode and the second electrode, a voltage is applied between the first electrode and the second electrode, and a current flowing through the teaching element generates heat to heat the money material or the oxide material, so that the side material is formed. -Window «feL rki irr

An IA is a magnetic sputtering or other suitable technique to coat a coating of a salt material with a relatively high electrical resistivity.

The source of hot electrons is really necessary. 1353616 SUMMARY OF THE INVENTION A thermal electron source includes a substrate, a thermal electron emitting body, a first electrode, and a second electrode, the substrate having a recess, the thermal electron emission The body corresponds to the groove and is disposed on the surface of the substrate, and is disposed at least partially through the groove of the substrate, the first electrode and the second electrode are spaced apart from each other and electrically connected to the thermal electron emitter In contrast to the prior art, the source of the hot electrons is a source of hot electrons 10. The hot electron emitter is spaced from the substrate by a recess of the substrate. The substrate does not heat the hot electron emitter. The generated heat is conducted into the atmosphere, so that the prepared hot electron source has excellent thermal electron emission performance. Moreover, the carbon nanotube film has low resistivity, and the prepared hot electron source can realize the emission of hot electrons at a low thermal power, thereby reducing the power consumption caused by heating during heat emission, and can be used for high current density and High-brightness flat panel display and logic circuits and other fields. [Embodiment] Lu The hot electron source of the present technical solution and a preparation method thereof will be described in detail below with reference to the accompanying drawings. Referring to FIG. 1, a hot electron source 10 prepared in an embodiment of the present technical solution includes a substrate 12, a thermal electron emitter 18, a first electrode 14, and a second electrode 16. The surface 121 of the substrate 12 has a recess 122. The thermal electron emitter 18 corresponds to the recess 122 and is disposed on the surface 121 of the substrate 12, and is spaced apart from the substrate 12 at least partially through a recess in the surface of the substrate 12. The first electrode 14 and the second electrode ι6 are spaced apart from each other and are in electrical contact with the thermionic emitter 18. 1353-616 • The hot electron source 1 further includes a low work function layer 20 disposed on a surface of the thermionic emitter 18. The material of the low-power layer is an oxidative lock or the like, which enables the hot electron source 10 to realize the emission of hot electrons at a lower temperature. The substrate 12 is made of an insulating material and may be ceramic, glass, resin, quartz or the like. The shape and size of the substrate 12 are not limited, and may be changed according to actual conditions. The substrate 12 in the embodiment of the technical solution is preferably a glass substrate. The recess 122 has a recess depth of 1 μm to 5 μm. The shape of the groove 122 is not limited, and the hot electron emitter 18 may be disposed at least partially through the groove 122 of the substrate 12 to be spaced apart from the substrate 12. In the embodiment of the technical solution, the groove has a rectangular parallelepiped shape with a length of 200 μm to 500 μm, a width of 1 μm to 3 μm, and a height of 10 μm to 50 μm. The thermal electron emitter 18 is a thin film structure or at least one long line. The material of the thermal electron emitter 18 is a boride, an oxide, a metal or a carbon nanotube. The thermal electron emitter 18 in the embodiment of the technical solution is selected as a carbon nanotube film structure. The carbon nanotube film structure comprises a carbon nanotube film or at least two carbon nanotube films arranged in an overlapping manner. The carbon nanotubes of the carbon nanotube film are arranged in a preferred orientation along the same direction. The carbon nanotubes in the single-layered carbon nanotube film are arranged in a direction extending from the first electrode 14 to the second electrode 16. The arrangement of the carbon nanotubes in the adjacent two carbon nanotube films in the overlapped carbon nanotube film has an intersection angle α and 〇. ^^9〇<^ The carbon nanotube film comprises a bundle of carbon nanotubes arranged in an end-to-end orientation and preferentially oriented, and adjacent nanotube bundles are connected by van der Waals force. The carbon nanotube bundle includes a plurality of tantalum 616 carbon nanotubes adjacent to each other and connected to each other by a van der Waals force. In the embodiment of the present invention, a super-sequential carbon nanotube array is grown on a 4-inch substrate by a CVD method, and further processed to obtain a carbon nanotube film. The carbon nanotubes in the carbon nanotube film are single-walled: a carbon nanotube, a double-walled carbon nanotube or a multi-walled carbon nanotube. When the carbon nanotubes in the carbon nanotube membrane are single-walled carbon nanotubes, the diameter of the single-walled carbon nanotubes is from 0.5 nm to 50 nm. When the carbon nanotube in the carbon nanotube film is a double-walled carbon nanotube, the diameter of the double-walled carbon nanotube is 1 〇 nanometer ~ % nanometer. When the carbon nanotubes in the carbon nanotube film are multi-walled carbon nanotubes, the diameter of the multi-walled carbon nanotubes is from 1.5 nm to 50 nm. It can be understood that the carbon nanotubes in the thin carbon nanotubes are arranged in a preferred orientation in the same direction. When a large substrate is used to grow ultra-sequential nanocarbon arrays, a wider carbon nanotube thinner can be obtained. In the embodiment of the technical solution, the width of the carbon nanotube film is obtained by growing a super-aligned carbon nanotube array on a 4-inch substrate by a CVD method and performing a step-by-step process to obtain a carbon nanotube film. It is 1 cm ~ 1 cm and has a thickness of 10 nm ~ 100 μm. The carbon nanotube film can be cut into a carbon nanotube film having a predetermined size and shape according to actual needs. Since the carbon nanotube tube in the super-sequential carbon nanotube array of the present embodiment is very pure, and since the specific surface area of the carbon nanotube itself is very large, the carbon nanotube film itself has strong viscosity. The carbon nanotube film can be directly fixed to the surface of the substrate 12 by its own viscosity. The thermal electron emitter 18 can also be attached to the surface of the substrate 12 by a conductive adhesive. The embodiment of the present invention preferably defines the hot electron emitter 18 on the surface of the substrate 12 by a conductive adhesive 1353616. The electrically conductive metal of the first electrode 14 and the second electrode 16. The first electrode 14 and the second electrode Μ 2 and the copper layer or the metal falling film pass through the consuming agent (the surface of the undetermined electron emitter 18, the first electrode 14) is entangled in the heat w and the second The electrode 16 may be selected from a conductive material such as graphite or a carbon nanotube. The first=U and the second electrode 16 may be a graphite layer, and a tantalum-carrying agent (the figure is fixed on the surface of the thermionic emitter 18) may also be subjected to a length of carbon nanotubes. The wire or the carbon nanotube film is directly fixed to the surface of the thermionic emitter 18 by its own dryness. The first electrode 14 and the second electrode 16 have a thickness of 10 μm to 50 μm. The interval between the first electrode 14 and the second electrode is 150 micrometers to 450 micrometers. The first electrode 14 and the second electrode 16 in the first embodiment of the present technical solution are preferably copper plating layers, respectively The bonding agent is fixed on the surface of the thermal electron emitter 18. Referring to FIG. 2, the embodiment of the present invention provides a method for preparing the thermal electron source 10, which specifically includes the following steps: Step 1: providing a substrate 12' A surface of the substrate 12 is formed with a recess 122. The substrate 12 of the embodiment of the present invention is preferably a glass substrate, and a recess 122 is formed on the glass substrate. Step 2: providing a thermal electron emitter 18, The hot electron emitter 18 corresponds to the recess 122 and lays the surface 121 of the substrate 12 . The hot electron emitter 18 is spaced apart from the substrate 12 by the recess 122 of the surface 121 of the substrate 12 . The example of the thermal electron emitter 18 is preferably one nanometer.

11 1353616 . Carbon tube film structure. The method for the carbon nanotube film structure corresponding to the groove i22 and covering the surface 121 of the substrate 12 and being spaced from the substrate 12 by the groove I22 of the substrate 12 includes: (1) Preparing at least one carbon nanotube film. The method for preparing the carbon nanotube film comprises the following steps: First, an array of carbon nanotubes is provided on a substrate, preferably the array is a super-sequential carbon nanotube array.

In this embodiment, the method for preparing the super-sequential carbon nanotube array adopts a chemical vapor deposition method, and the specific steps thereof include: (a) providing a flat bottom, and the substrate may be a P-type or N-type stone base. Or use the sound of the stone base substrate 'this embodiment is preferably a 4 inch stone base; (1) = the bottom surface uniformly forms a catalysis, the catalyst layer # material can be selected from iron Fe), cobalt (c〇), nickel (Ni Or one of the alloys of any combination thereof. (c) The substrate on which the catalyst layer is formed is at 7 〇 (TC~90 (TC air retreat, about 30 minutes to 90 minutes; (4) the treated substrate is placed in the reaction In the furnace, the gas is heated to the thief, then the carbon source gas is passed into the carbon source gas for about 5 77 to 3 〇 minutes, and the growth is obtained by super-sequential carbon nanotube array, the height of which is 200 μm~_micron. The super-sequential carbon nanotube array is pure nano-tube formed by parallel and perpendicular to the growth of the carbon nanotubes. The super-sequential carbon nanotubes contain substantially no impurities, such as none. Shaped carbon or residual catalyst metal. The carbon nanotube array makes the nano carbon The array is formed by van der Waals=contact. The area of the carbon nanotube array is substantially the same as the area of the above substrate. (S) 12 1353.616 • The above carbon source gas may be made of acetylene, ethylene, decane, etc. The carbon source gas of the present embodiment is acetylene; the gas of the shielding gas is nitrogen or an inert gas, and the preferred shielding gas of the embodiment is argon. It can be understood that the carbon nanotube array provided by the embodiment It is not limited to the above preparation method', but it may also be a graphite electrode constant current arc discharge deposition method, a burst deposition method, etc. ^ Next, a carbon nanotube array is taken by a stretching tool to obtain a carbon nanotube film. > In the present embodiment, the method for drawing the carbon nanotube array by using a stretching tool to obtain a carbon nanotube film comprises the following steps: (a) selecting a certain width from the carbon nanotube array. a plurality of carbon nanotube bundle segments; (b) stretching the plurality of carbon nanotube bundle segments at a constant speed along a growth direction substantially perpendicular to the carbon nanotube array growth direction to obtain a continuous carbon nanotube film, The carbon nanotubes in the carbon nanotube film are arranged in the stretching direction. During the above stretching process, the plurality of carbon nanotube bundle segments are gradually separated from the substrate in the stretching direction under the pulling force, due to the van der Waals By force, the selected plurality of carbon nanotube bundle segments are continuously pulled out end to end with other carbon nanotube bundle segments to form a carbon nanotube film. The carbon nanotube film is arranged in a preferred orientation. A plurality of carbon nanotube bundles are formed end to end to form a carbon nanotube film having a certain width. It is understood that the carbon nanotubes in the carbon nanotube film are preferentially oriented in the same direction, and the ten and two will be at least - Nai (four) tube thin layer should be placed on the surface 121 of the substrate 12, forming a Taicheng not a slave official thin structure as a heat emission ^ 18 'The carbon nanotubes tie knots toughness 12 table

13 1353616. The groove 122 of the face 121 is spaced apart from the substrate 12. Progressively, a work function layer 2〇 may be formed on the surface of the carbon nanotube film structure by sputtering, vacuum evaporation, or the like, and the material of the work function layer 20 may be ruthenium oxide or knock So that the hot electron source (7) achieves the emission of hot electrons at a lower temperature. The method of laying at least the carbon nanotube film on the surface 121 of the substrate 12 corresponding to the groove 122 includes the step of extending a film of the carbon nanotube from the first electrode 14 to the second electrode 16 The direction is directly applied to the surface 121 of the substrate 12 to form a carbon nanotube film structure 18. Or at least two nano-carbon f films are laid directly on the surface of the substrate 12 at an angle and an angle according to the arrangement direction of the carbon nanotubes, and 03C90. Forming a carbon nanotube film structure 18. The carbon nanotube film structure 18 can be directly fixed to the substrate i surface 121 by the present invention. It can be understood that the method of laying at least one carbon nanotube film corresponding to the groove 122 on the surface m of the substrate 12 may further include the following steps: providing a support body; and at least two carbon nanotube films According to the arrangement direction of the carbon nanotubes, the surface of the support body is directly laid at an overlap angle α, and is 0SK90. Obtaining a carbon nanotube film structure 18; removing excess carbon nanotube film outside the support; treating the carbon nanotube film structure 18 with an organic solvent; and processing the film structure 18 using an organic solvent The support body is removed to form a self-supporting carbon nanotube film structure 18; the self-supporting carbon nanotube film structure 18 is laid on the surface 121 of the substrate 12 corresponding to the groove 122. The nanocarbon film can be directly fixed to the support by its own viscosity. 1353616 — The actual % of the case, the size of the above support can be determined according to actual needs. It is understood that the above-described carbon nanotube film structure 18 can be positioned on the substrate η surface 121 by coating a surface of the substrate 12 with a conductive adhesive.

The present embodiment can further process the organic solvent by placing the at least one carbon nanotube film V groove 122 directly on the surface 121 of the substrate 12 to form the second layer: Nano anti-B 4 membrane structure 18. The timing solvent treatment of the carbon nanotube thinner includes: passing the organic solvent to the nano carbon half surface to infiltrate the entire carbon nanotube film, or the entire nanomembrane structure 18 Soaked in a container filled with organic solvents. The organic agent is a volatile organic solvent, such as ethanol, methanol, propylene mesh, and the like: ethanol is used in the embodiment of the technical scheme. After the solvent infiltration treatment of the carbon nanocarbon is carried out, in the volatile organic solvent (four) segment, the parallel carbon nanotubes in the carbon nanotube film structure 18 are aggregated into a carbon nanotube bundle. Therefore, the nanometer is used after the treatment. /, "," 18 mechanical strength and toughness is enhanced, the viscosity is weakened, and it is convenient to form an electrical contact with a second electrode 16' at the surface of the surface of the thermal electron emitter 18 to form an electrical contact with the thermal electron emitter. 18(d) contact 'and thereby obtain-thermal electron source 10. Electron=!! The first drain 14 and the second electrode 16 are spaced apart from the side electron source 10 when the U surface 'to apply the thermal electron emitter 18 (4) -electrode The first resistance is formed by the screen printing method, the offset printing method 15 1353616, the electrostatic spraying method, the electrophoresis method, the photolithography method, and the thermal electron emission. The surface of the body 18, further; = agent (not shown) is fixed on the surface of the thermionic emitter 18, ''the embodiment of the present invention preferably forms a first electrode 14 and the surface of the screen emitter"; = Thermal: The sub-body comprises the following steps: A first electrode 16 having (1) providing a conductive paste.

The conductive paste includes a conductive material, a dry agent, and an organic machine auxiliary. The conductive material is conductive gold such as gold, silver, steel, etc.: dry from inorganic binder, organic binder and low = species or multiple. Inorganic (four) agents can include glass powder, I = glass. The organic binder may include a fiber resin such as acetaminophen: an acrylic resin such as polyacetal vinegar, a county propylene ketone, and a ketone acrylic acid; and a B-resin resin. The dry agent has a certain degree of dryness, which enables the particles of the conductive material to be reduced and the conductive paste to be on the surface of the electron emitter 18. The conductive material and the knotting agent are in the range of ο.1.10~1〇:ι. If the weight of the conductive material and the binder is less than 〇.1:10, cracks are likely to occur due to stress. If the weight ratio of the conductive material to the junctioning agent is greater than yang, the emission properties of the hot electron source 10 are affected. Further, θ, a plurality of organic solvents and organic auxiliaries may be added to the conductive paste, including adding (four), a dispersing agent, a plasticizer or a surfactant, etc., to adjust the dryness, fluidity, and drying of the conductive material. Physical properties such as speed 'to facilitate coating. The organic solvent and the auxiliary agent to be used are not particularly limited except for a general organic solvent such as ethanol, ethylene glycol, ethyl propanol, hydrocarbon 16 1353616, water, a mixed solvent thereof, and other frequently added ones may be appropriately selected. A plasticizer such as diethyl oxalate, low glass powder, or butyl ether, which is a slower solvent, can enhance the plasticity of the conductive paste after the addition. The amount of the organic solvent and the auxiliary agent added is mainly determined according to the printing process. After the above conductive paste is prepared, it is placed in a stirring device to uniformly mix the conductive material. The preferred conductive paste of the embodiment of the present invention contains 75% silver, 2% by weight binder, 3% by weight low glass powder and 2% by weight ethanol. Among them • The knotting agent is a solution of ethyl cellulose in terpineol. The conductive paste prepared in a certain proportion is ground in a three-roller, so that the components in the conductive polymer are uniformly mixed. (2) The above conductive paste is applied to the surface of the ruthenium emitter 18 in a predetermined pattern. The above conductive paste is applied to the surface of the thermionic emitter 18 by screen printing in a predetermined pattern. With this method, a finer thermal electron emitter pattern can be prepared, which can be applied to a higher resolution flat display device. (3) The above-described thermal electron emitters 18 coated with a conductive paste are thermally treated to form a first electrode 14 and a second electrode 16 spaced apart from each other on the surface of the hot electron emitter 18. The treatment is usually carried out by adding the thermal electron emitter 18 coated with the conductive paste in an atmosphere or an oxidizing gas-containing environment. The heating temperature of the heat treatment is confirmed in accordance with the composition of the conductor paste. The purpose of the heat treatment is to remove the organic component in the conductive paste, so that the conductive paste does not contain non-volatile or non-decomposable components, and the first electrode 14 and the second are described. A good mechanical and electrical contact is formed between the electrode 16 and the hot electron emitter 18. Usually, the heating temperature of the heat treatment • Do not exceed 6001. Since the heat treatment temperature is higher than 6 〇〇〇c, the carbon nanotubes may be destroyed. Preferably, the process of heat-treating the conductive paste in the embodiment of the technical solution comprises the following steps: first from 2 Torr. (: The conductive paste was initially heated for 10 minutes to reach 120. (:, held at 120 ° C for 10 minutes to remove terpineol and ethanol in the conductive paste; secondly, the conductive paste was continued to rise • Warm for 30 minutes up to 35 (rc, hold at 35 (rc for 3 〇 minutes to remove ethylcellulose in the conductive paste; again, continue to heat the conductive paste for 30 minutes until 515t, keep warm at 5151 After 30 minutes, the conductive paste is tightly bonded to the thermal electron emitter 18, and finally the conductive paste is naturally cooled, thereby forming a first electrode 14 and a second electrode on the surface of the thermal electron emitter 18. 16. A good mechanical and electrical contact is formed between the first electrode 14 and the second electrode 16 and the thermionic emitter 18. The thermal electron source is a side heat compared to the prior art. An electron source, the hot electron emitter is disposed apart from the substrate by a groove of the substrate, and the substrate does not conduct heat generated by heating the thermal electron emitter into the atmosphere, so the prepared hot electron source Excellent thermal electron emission performance. Moreover, the carbon nanotube film has low resistivity, and the prepared hot electron source can realize the emission of hot electrons at a low heat power, reducing the power consumption generated by heating at the time of heat emission, and can be used for large current density. And high-brightness flat display and logic circuits and the like. In summary, the present invention has indeed met the requirements of the invention patent, and is stipulated in accordance with the law 18 (S) patent application. However, the above is only the present invention. The preferred embodiment of the present invention is not limited to the scope of the patent application. The equivalent modifications or variations of the present invention in the spirit of the present invention are intended to be included in the following claims. 1 is a schematic structural view of a hot electron source according to an embodiment of the present technical solution. FIG. 2 is a schematic flow chart of a method for preparing a hot electron source according to an embodiment of the present technical solution.

[Main component symbol description] Thermoelectron source substrate

10 12 14 16 18 20 121 122 First electrode First electrode Thermal electron emitter Low work function layer Substrate surface Groove c S ) 19

Claims (1)

1353616 • X. Patent Application 1 1. A source of thermal electrons comprising a substrate, a thermal electron emitter, a first electrode and a second electrode, the first electrode and the second electrode being spaced apart from each other The electron emitter electrical contact is improved in that the substrate has a recess, and the thermal electron emitter corresponds to a concave surface of the substrate. The thermal electron source of claim 1, wherein the thermal electron emitter is spaced apart from the substrate at least partially through a recess of the substrate. 3. The hot electron source of claim 1, wherein the recess has a recess depth of from 1 μm to 50 μm. 4. The hot electron source of claim 1, wherein the thermal electron emitter is a thin film structure or at least one long line. 5. The hot electron source according to claim 4, wherein the thermal electron emitter is a carbon nanotube film structure, and the carbon nanotube 1 film structure comprises at least one carbon nanotube film. The carbon nanotubes in the carbon nanotube film are arranged in a preferred orientation in the same direction. 6. The hot electron source according to claim 5, wherein the carbon nanotube film structure comprises a carbon nanotube film, and the carbon nanotubes in the carbon nanotube film are from the The first electrodes are arranged in a direction in which the first electrodes extend. The hot electron source according to claim 5, wherein the carbon nanotube film structure comprises at least two carbon nanotube films arranged in an overlapping manner, and the phase of the carbon nanotube film disposed in the overlap The arrangement of the nanotubes in the adjacent two 20 carbon nanotube films has an angle of intersection α and 〇γα59〇. . The hot electron source according to claim 5, wherein the carbon nanotubes have a width of from 1 cm to 1 cm and a thickness of from 10 nm to 100 μm. 9. The hot electron source according to claim 5, wherein the non-carbon carbon film comprises a plurality of carbon nanotubes arranged end to end and in a preferred orientation, and between adjacent carbon nanotube bundles Connected to Van der Valli. The hot electron source according to claim 9, wherein the nano beam comprises a plurality of carbon nanotubes of equal length and spaced apart from each other, and adjacent carbon nanotubes pass between Van der Valli is connected. 11. The hot electron source of claim i, wherein the source of thermal electrons further comprises a low work function layer disposed on a surface of the hot electron emitter. The hot electron source according to claim 11, wherein the material of the low work function layer is ruthenium oxide or a cooker. twenty one