JP3985776B2 - Method for improving electron emission characteristics of carbon nanotube aggregate substrate and apparatus equipped with the substrate - Google Patents
Method for improving electron emission characteristics of carbon nanotube aggregate substrate and apparatus equipped with the substrate Download PDFInfo
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本発明は、カーボンナノチューブ集合体を付着させた基板の電子放出特性向上方法及びこの基板を装着した装置に関するものである。 The present invention relates to a method for improving electron emission characteristics of a substrate on which a carbon nanotube aggregate is adhered, and an apparatus equipped with the substrate.
カーボンナノチューブは、化学的気相成長法（ＣＶＤ法）またはアーク放電法等によって生成され、炭素原子が六角形状に規則正しく並んだシート（以下、グラフェンシートと称す。）が、円筒形に丸まったものであり、特異な性質を有していることから新素材として注目されている。 Carbon nanotubes are produced by chemical vapor deposition (CVD) or arc discharge, etc., and a sheet in which carbon atoms are regularly arranged in a hexagonal shape (hereinafter referred to as graphene sheet) is rolled into a cylindrical shape. It has attracted attention as a new material because of its unique properties.
なお、グラフェンシートの筒が一重のものを単層カーボンナノチューブ（ＳＷＣＮＴ）と称し、その直径は１〜数ｎｍ、長さは１〜数十μｍ程度である。一方、グラフェンシートの筒が同心状に何重も重なっているものを多層カーボンナノチューブ（ＭＷＣＮＴ）と称し、その直径は数ｎｍ〜数十ｎｍである。また、グラフェンシートが略円錐状に丸まったものをカーボンナノホーンと称し、単層または多層カーボンナノホーン（ＳＷＣＮＨ、ＭＷＣＮＨ）がある。本発明においては、これらをカーボンナノチューブ（以下、ＣＮＴと称す。）と総称する。また、このＣＮＴ単体をＣＮＴ繊維、該ＣＮＴ繊維が集合したものをＣＮＴ集合体と称す。 A single graphene sheet tube is referred to as a single-walled carbon nanotube (SWCNT), and has a diameter of 1 to several nm and a length of about 1 to several tens of μm. On the other hand, multi-layer carbon nanotubes (MWCNTs) in which graphene sheet tubes are concentrically overlapped are referred to as multi-walled carbon nanotubes (MWCNTs) and have a diameter of several nanometers to several tens of nanometers. A graphene sheet rounded into a substantially conical shape is called a carbon nanohorn, and there are single-layer or multi-layer carbon nanohorns (SWCNH, MWCNH). In the present invention, these are collectively referred to as carbon nanotubes (hereinafter referred to as CNT). Further, this single CNT is referred to as a CNT fiber, and a collection of the CNT fibers is referred to as a CNT aggregate.
このＣＮＴの先端部は非常に高い電界電子放出特性を有しており、蛍光表示管、Ｘ線管、フィールドエミッションディスプレイ（ＦＥＤ）等の電界放出型冷陰極用材料として、実用化が検討されている。 The tip of this CNT has very high field electron emission characteristics, and its practical application as a field emission cold cathode material for fluorescent display tubes, X-ray tubes, field emission displays (FEDs), etc. has been studied. Yes.
ところで、電界放出型冷陰極素子への実用化に最も必要な技術は、ＣＮＴを基板材料に貼付けて電極とした状態において高い電子放出性を得ることである。そのためにはＣＮＴ先端部を基板面と垂直な方向へ配向させる（毛羽立たせる）ことが必要であり、そのための方法が数多く提案されている。 By the way, the most necessary technique for practical application to a field emission cold cathode device is to obtain a high electron emission property in a state where CNT is attached to a substrate material to form an electrode. For this purpose, it is necessary to orient the CNT tip in a direction perpendicular to the substrate surface (fluffing), and many methods have been proposed.
アーク放電、ＣＶＤ法等によりＣＮＴはほとんどの場合単体で生成されるため、これを用いたＣＮＴ電極素子の製作は、ＣＮＴ繊維を導電性ペースト材料に混ぜて、陰極基板にスクリーン印刷等により成膜する方法が一般的である。この状態ではほとんど電子放出を得られないため、例えば、特許文献１に記載されているように成膜後に球状粉末を散布、除去することで凹凸を付け凸部においてＣＮＴを垂直に配向させる方法が提案されている。
Since CNTs are almost always produced by arc discharge, CVD method, etc., CNT electrode elements using this are produced by mixing CNT fibers with conductive paste material and forming a film on the cathode substrate by screen printing etc. The method to do is common. In this state, since almost no electron emission can be obtained, for example, as described in
また、導電性ペーストに埋もれた状態のＣＮＴ先端をレーザ照射、プラズマ、エッチング等で露出させる方法が特許文献２に提案されている。例えばレーザ照射は、ＹＡＧレーザを用い、約１．１Ｊの条件で０．６〜０．７ｍｓの間隔でパルス照射することによって行っている。
Further,
前述の方法では、得られたＣＮＴ基板の電子放出能が低いという問題があった。 The above-described method has a problem that the electron emission ability of the obtained CNT substrate is low.
本発明は、かかる問題を解決するためになされたものであり、電子放出特性が一様であってしかも能力が大きいＣＮＴ集合体基板の製造方法、及びこの方法で得られた基板が装着された装置を提供することを目的とする。 The present invention has been made to solve such a problem, and has a method of manufacturing a CNT aggregate substrate having uniform electron emission characteristics and high capability, and a substrate obtained by this method is mounted. An object is to provide an apparatus.
本発明者らは、従来この方法ではＣＮＴ繊維とペースト材料の混合材料（通常１〜１０％程度、最大でも５０％である。）であるため、ＣＮＴ繊維を一様かつ高密度で基板へ成膜させることが難しいこと、さらに、成膜したままでは、ＣＮＴ繊維が基板面とほとんど平行に近い（寝た）状態でペースト材料のなかに埋め込まれており、このような状態においてどのような表面処理を施しても、基板に対しＣＮＴが垂直方向に配向したＣＮＴ先端部を露出させた状態を得ることは確率的に低く、一様かつ高い電子放出特性を得ることは本質的に困難であるという結論に達した。 In the conventional method, since the present inventors are a mixed material of CNT fibers and paste material (usually about 1 to 10%, and at most 50%), the CNT fibers are uniformly and densely formed on the substrate. It is difficult to form a film, and as it is, the CNT fibers are embedded in the paste material in a state almost parallel to the substrate surface (sleeping). Even if the treatment is performed, it is stochastically low to obtain a state in which the CNT tip portion in which the CNTs are vertically aligned with respect to the substrate is obtained, and it is essentially difficult to obtain uniform and high electron emission characteristics. The conclusion was reached.
そこで、カーボンナノチューブ集合体を有機バインダーや導電性ペースト等を用いないで露出した状態で基板上に付着させ、これに特定波長のレーザを一定のエネルギー密度で照射することによってカーボンナノチューブ集合体そのものさらには該集合体間をも解きほぐして全体を毛羽立たせることができ、それによって、一様かつ高い電子放出特性を有するカーボンナノチューブ集合体の基板を得ることができた。 Therefore, the carbon nanotube aggregate is attached to the substrate in an exposed state without using an organic binder or a conductive paste, and the carbon nanotube aggregate itself is further irradiated by irradiating a laser with a specific wavelength at a constant energy density. Was able to unravel between the aggregates and make the whole fluffy, thereby obtaining a carbon nanotube aggregate substrate having uniform and high electron emission characteristics.
すなわち、本発明はカーボンナノチューブ集合体が露出状態で付着している基板表面に、３８０ｎｍ超１１００ｎｍ以下の波長のレーザを１００ｍＪ／ｃｍ 2 以上１０００ｍＪ／ｃｍ 2 以下のエネルギー密度で照射することを特徴とする、該基板の電子放出特性向上方法、及びこの方法で得られた基板を装着している電気機器又は電子機器に関するものである。 That is, the present invention provides a feature to irradiate the substrate surface aggregates of carbon nanotubes are deposited in exposed state, a laser of 380nm ultra 1100nm wavelengths below at 100 mJ / cm 2 or more 1000 mJ / cm 2 or less of the energy density The present invention relates to a method for improving electron emission characteristics of a substrate, and an electric device or electronic device on which a substrate obtained by this method is mounted.
この本発明のＣＮＴ集合体基板の加工方法は、下記のように行われる。 The processing method of the CNT aggregate substrate of the present invention is performed as follows.
複数のＣＮＴが絡み合って一体化して生成されたＣＮＴ集合体の層を一様な層厚で電極基板上に生成させる。このとき、ＣＮＴは基板面に垂直な方向へ配向させる必要はなく、むしろ全体的にはＣＮＴの軸方向が基板と平行方向に配向した（寝た）状態で均一なものが良い。 A layer of a CNT aggregate generated by intertwining a plurality of CNTs is formed on the electrode substrate with a uniform layer thickness. At this time, the CNTs do not need to be oriented in a direction perpendicular to the substrate surface, but rather, the CNTs are preferably uniform in a state where the axial direction of the CNTs is oriented (sleeped) in a direction parallel to the substrate.
次に、このＣＮＴ集合体の層表面にレーザを照射すると、レーザのエネルギーはＣＮＴ層に吸収され、基板と平行状態やだまになっているＣＮＴ同士が密着したＣＮＴ集合体は、ほぐされて浮上がり、さらには端部が毛羽立った状態を得ることができる。これはレーザによるＣＮＴの電磁波吸収、それによる振動、共鳴やＣＮＴの急激な温度上昇が引き起こされることを要因とした、表層ＣＮＴの一部飛散、昇華や周囲ガスの急激な膨張圧力や気流より、ＣＮＴ集合体が解きほぐされたり、さらにはＣＮＴ端部が基板上方へ向くと考えられる。 Next, when the surface of the layer of the CNT aggregate is irradiated with laser, the energy of the laser is absorbed by the CNT layer, and the CNT aggregate in which the CNTs that are in parallel with the substrate or in contact with each other are loosened is loosened and floated. As a result, it is possible to obtain a state in which the edges are raised and the ends are fluffy. This is due to the absorption of electromagnetic waves of CNTs by the laser, vibrations caused by it, resonance and rapid temperature rise of CNTs, due to partial scattering of surface CNTs, sublimation and rapid expansion pressure and airflow of surrounding gas, It is considered that the CNT aggregate is unraveled, and further, the end of the CNT faces upward from the substrate.
以上より、レーザ照射により、ＣＮＴ繊維が解きほぐされたりＣＮＴ端部が毛羽立った状態となるため、非常に高い電子放出特性を有するＣＮＴ集合基板が得られる。 From the above, since the CNT fibers are unraveled or the CNT ends become fuzzy by laser irradiation, a CNT aggregate substrate having very high electron emission characteristics can be obtained.
以上のように本発明において、以下のような顕著な効果が得られる。
１）．複雑な工程と時間が必要な熱処理や化学処理ではなく、レーザ照射方法は簡素かつ短時間で安価な装置で、ＣＮＴ集合体基板を高い均一性あるいは任意形状に高電子放出特性を得る表面加工法が得られる。また電子放出特性値もコントロール可能である。
２）．照射前のＣＮＴ集合体基板は、毛羽立ちが必要なく繊維が全体として寝ている状態のものがよいため、スプレーによる塗布や押付ける方法等の容易な方法にて簡単に製作できる。さらに、ナノポリへドロン、アモルファスカーボン等のＣＮＴ以外の混入した不純物はレーザ照射により飛散、蒸発して除去することが可能である。
３）．また、毛羽立ち状況と領域を制御できるため、電子放出特性の悪い個所に照射して特性を発揮させる追加工処理が可能である。
As described above, in the present invention, the following remarkable effects can be obtained.
1). Rather than heat treatment and chemical treatment that require complicated processes and time, the laser irradiation method is a simple, inexpensive and surface-processing method that obtains high electron emission characteristics in a highly uniform or arbitrary shape on a CNT aggregate substrate Is obtained. The electron emission characteristic value can also be controlled.
2). Since the CNT aggregate substrate before irradiation is not required to be fluffed and the fiber is lying as a whole, it can be easily manufactured by an easy method such as spraying or pressing. Further, impurities such as nanopolyhedron and amorphous carbon other than CNT can be removed by scattering and evaporation by laser irradiation.
3). Further, since the fuzzing state and the region can be controlled, it is possible to perform an additional process for irradiating a portion having poor electron emission characteristics to exhibit the characteristics.
本発明で使用されるカーボンナノチューブ集合体は特に限定されるものではなく、化学的気相成長法、アーク放電法等如何なる方法で得られたものであってもよい。 The aggregate of carbon nanotubes used in the present invention is not particularly limited, and may be obtained by any method such as a chemical vapor deposition method or an arc discharge method.
基板材料として電界放出型冷陰極用材料として用いられるニッケル、アルミニウム、ステンレス、銅、タングステン及びそれらのいずれかを含む合金等の導電性の金属やガラス系材料、セラミックス系材料等、種々材料が使用可能である。ガラス系材料やセラミックス系材料の場合、前記導電性金属等を表面に蒸着等で被覆させて用いることができ、基板の形状や大きさは基板の用途等に応じて定まるが、通常は、基本形状が円形、４角形、長方形等の板状、等である。 Various materials such as conductive metals such as nickel, aluminum, stainless steel, copper, tungsten and alloys containing any of them, glass-based materials, ceramic-based materials, etc. are used as substrate-emitting cold cathode materials as substrate materials Is possible. In the case of glass-based materials and ceramic-based materials, the conductive metal can be coated on the surface by vapor deposition, etc., and the shape and size of the substrate are determined according to the use of the substrate, etc. The shape is a circular plate shape, a quadrangular shape, a rectangular shape, or the like.
カーボンナノチューブ集合体を付着させる面は鏡面加工あるいは脱脂処理、酸化膜除去たとえば熱処理イオンボンバート等の前処理を施すことができる。 The surface on which the carbon nanotube aggregate is attached can be subjected to a pre-treatment such as mirror finishing or degreasing treatment, oxide film removal such as heat treatment ion bombardment.
カーボンナノチューブ集合体を基板表面に露出状態で付着させる方法としては、カーボンナノチューブを分散媒中に分散させてスプレー等で散布する方法（スプレー堆積法）、シート状（テープ状を含む。）のカーボンナノチューブ集合体をアルコールで貼り付ける方法を利用できる。 As a method of attaching the aggregate of carbon nanotubes to the substrate surface in an exposed state, carbon nanotubes are dispersed in a dispersion medium and sprayed or the like (spray deposition method), or sheet-like (including tape-like) carbon. A method of attaching a nanotube aggregate with alcohol can be used.
スプレー堆積法に用いる分散媒としては、メタノール、エタノール、イソプロピルアルコール等のアルコール、純水等を用いることができる。分散媒に分散させるカーボンナノチューブの濃度としては、要はこれを均一に散布できる程度でよく、例えば０．０５〜０．５ｍｇ／ｃｍ3程度が適当である。カーボンナノチューブを投入した分散媒は、超音波処理するなどして均一に分散させてから散布するのがよい。散布はスプレー等を用いて常温で行えばよく、その後は放置して自然乾燥すればよい。 As a dispersion medium used in the spray deposition method, alcohol such as methanol, ethanol, isopropyl alcohol, pure water, or the like can be used. The concentration of the carbon nanotubes dispersed in the dispersion medium may be such that the carbon nanotubes can be uniformly dispersed, for example, about 0.05 to 0.5 mg / cm 3 is appropriate. The dispersion medium charged with carbon nanotubes is preferably dispersed after being uniformly dispersed by ultrasonic treatment or the like. The spraying may be performed at room temperature using a spray or the like, and then left to dry naturally.
基板との付着力はファンデルワールス力によるものと考えられ、状態を維持するのに十分なものである。 Adhesion with the substrate is thought to be due to van der Waals forces and is sufficient to maintain the state.
さらに、これらの方法ではカーボンナノチューブ集合体の基板への付着が不充分な場合には、カーボンナノチューブ集合体を導電性接着剤やろう材で基板に接着接合させることもできる。その場合でも接着剤やろう材がカーボンナノチューブ集合体の表面まで滲み出てこないようにする必要がある。 Further, in these methods, when the carbon nanotube aggregate is insufficiently attached to the substrate, the carbon nanotube aggregate can be adhesively bonded to the substrate with a conductive adhesive or a brazing material. Even in such a case, it is necessary to prevent the adhesive or brazing material from seeping out to the surface of the carbon nanotube aggregate.
カーボンナノチューブを基板にろう付するために用いるろう材は低い融点の金属（合金を含む。）や金属化合物であり、かつ、ＣＮＴ及び基板に濡れ性のよいものである。ろう材の融点は、ＣＮＴの分解、ダメージを与えない１５０〜８００℃のものがよい。 The brazing material used for brazing the carbon nanotubes to the substrate is a metal having a low melting point (including an alloy) or a metal compound, and has good wettability to the CNT and the substrate. The melting point of the brazing material is preferably 150 to 800 ° C. which does not decompose or damage the CNTs.
ろう材料の例としては、基板がステンレススチールの場合には、インジウム、インジウム系はんだ等を用いることができる。 As an example of the brazing material, when the substrate is stainless steel, indium, indium solder, or the like can be used.
ろう付けを行う場合には、ろう材をまず基板材のろう付け面に付着させる。 When brazing is performed, the brazing material is first adhered to the brazing surface of the substrate material.
ろう材の基板面への付着は、均一に行うため、蒸着が好ましいが、その他の付着手段、例えば粉末ろう材の散布、懸濁液や溶液の吹付けあるいはその他の手段による塗布、箔等にしての貼着等、如何なる手段によってもよい。ただし、ろう材の膜厚は、ＣＮＴの膜厚以下が必要である。例えば１〜１００μｍ程度、通常５〜５０μｍ程度でよい。 Vapor deposition is preferable because the brazing material adheres uniformly to the substrate surface. However, other adhering means such as spraying powder brazing material, spraying suspension or solution or applying by other means, foil, etc. Any means such as pasting may be used. However, the film thickness of the brazing material needs to be equal to or less than the film thickness of CNT. For example, it may be about 1 to 100 μm, usually about 5 to 50 μm.
ＣＮＴの基板へのろう付けは、この状態でＣＮＴを基板面に密着させて加熱する。 For brazing the CNTs to the substrate, the CNTs are brought into close contact with the substrate surface and heated in this state.
ＣＮＴの基板面への密着は、ＣＮＴが前記のスプレー堆積法により基板等に付着されたものあるいは膜状、シート状等の成形品であればこれを基板面に押付ければよい。 The close contact of the CNTs with the substrate surface may be achieved by pressing the CNTs on the substrate surface if the CNTs are attached to the substrate or the like by the spray deposition method or a molded product such as a film or sheet.
加熱は、ろう材およびＣＮＴが酸化変質しない雰囲気がよく、これはろう材が安定でありかつＣＮＴが変質や分解しない温度と時間であれば大気中でもよい。必要により、真空（減圧）あるいは、Ｎ2、Ｈｅ、Ａｒ等の不活性ガス雰囲気が用いられる。 The heating is preferably performed in an atmosphere in which the brazing material and the CNTs are not oxidized and denatured, and this may be in the atmosphere as long as the brazing material is stable and the CNTs are not denatured or decomposed. If necessary, vacuum (reduced pressure) or an inert gas atmosphere such as N 2 , He, Ar or the like is used.
以上の説明でわかるように、本発明でレーザが照射される基板の表面にカーボンナノチューブ集合体が全面に分布して露出している。また、このカーボンナノチューブ集合体は層厚では１〜５００μｍ程度、通常５〜１００μｍ程度、特に１０〜５０μｍ程度である。 As can be seen from the above description, aggregates of carbon nanotubes are distributed and exposed on the entire surface of the substrate irradiated with the laser in the present invention. The aggregate of carbon nanotubes has a layer thickness of about 1 to 500 μm, usually about 5 to 100 μm, particularly about 10 to 50 μm.
こうして得られるカーボンナノチューブ集合体が付着している基板表面にレーザを照射する。このレーザは基板表面に付着しているカーボンナノチューブ集合体そのものさらには該集合体間をも解きほぐして全体を毛羽立たせるために用いられるものである。照射するレーザのエネルギー密度は１０〜３０００ｍＪ／ｃｍ2、好ましくは１００〜１０００ｍＪ／ｃｍ2、より好ましくは２００〜５００ｍＪ／ｃｍ2の範囲で、ＣＮＴ集合体の性質（単層、多層、長さ、密度、純度）やＣＮＴ集合体膜の条件（膜厚、密度等）により最適値と照射回数を調整する。エネルギー密度が低いとＣＮＴ膜には何の変化もなく照射効果もなくなる。逆にエネルギー密度が高すぎるとＣＮＴが多く飛散するようになる。レーザのエネルギー照射時間（１回のレーザパルス時間）の関係としては、図３に斜線で示す領域である。さらに照射するレーザのパワー密度としては１０7〜１０8Ｗ／ｃｍ2範囲が好ましい。レーザ波長の影響としては、短波長ほど光子エネルギーが高く、低いエネルギーで効果を得ることができると考えられる。ただし３８０ｎｍ以下の紫外領域では光子エネルギーが炭素間の結合エネルギーを超え、カーボンナノチューブが分解、損傷する可能性が高くなる。また波長が長くなるほど光子エネルギーＣＮＴへの吸収率低くなるため効果が悪くなり、ビームのスポット径も広がるため赤外波長域は適さない。以上より、波長範囲としては３８０ｎｍ超１１００ｎｍ以下、より好ましくは４５０ｎｍ超６８０ｎｍ以下が最適な波長であると考えられる。 The surface of the substrate on which the carbon nanotube aggregate thus obtained is attached is irradiated with laser. This laser is used for unraveling the carbon nanotube aggregates adhering to the substrate surface as well as between the aggregates to make the whole fluffy. Energy density of the laser to be irradiated 10~3000mJ / cm 2, preferably in the range of 100~1000mJ / cm 2, more preferably 200~500mJ / cm 2, the nature of the CNT aggregate (monolayer, multilayer, length, The optimum value and the number of times of irradiation are adjusted according to the conditions (thickness, density, etc.) of the CNT aggregate film and the density and purity. When the energy density is low, there is no change in the CNT film and the irradiation effect is lost. Conversely, if the energy density is too high, a lot of CNTs will be scattered. The relationship of the laser energy irradiation time (one laser pulse time) is a region indicated by hatching in FIG. Further, the power density of the irradiated laser is preferably in the range of 10 7 to 10 8 W / cm 2 . As the influence of the laser wavelength, it is considered that the shorter the wavelength, the higher the photon energy, and the effect can be obtained with lower energy. However, in the ultraviolet region of 380 nm or less, the photon energy exceeds the binding energy between carbons, and the possibility that the carbon nanotubes are decomposed and damaged increases. In addition, the longer the wavelength, the lower the absorption rate to the photon energy CNT, so the effect becomes worse, and the spot diameter of the beam widens, so the infrared wavelength region is not suitable. From the above, it is considered that the optimum wavelength range is more than 380 nm and less than 1100 nm, more preferably more than 450 nm and less than 680 nm.
レーザの照射は、円形ビームをレンズで集束させてスポット状に照射してもよく、シリンドリカルレンズや特殊レンズを用いてビームをライン状にして照射してもよい。 Laser irradiation may be performed by converging a circular beam with a lens and irradiating it in a spot shape, or using a cylindrical lens or a special lens to irradiate the beam in a line shape.
本発明でレーザが照射されるＣＮＴ集合体基板の構造を図１に模式的に示す。 FIG. 1 schematically shows the structure of a CNT aggregate substrate irradiated with a laser in the present invention.
図１（Ａ）のＣＮＴ集合体基板は基板１１の上にＣＮＴ集合体１２を直接付着させたものであり、図１（Ｂ）ではろう材や接着剤等のインサート材１３を介して付着させたものである。これにレーザを照射している状態を図２に模式的に示す。図２(Ａ)では、レーザ発振器２１から発せられる円形ビームをレンズ２２で集束させてＣＮＴ集合体基板にスポット照射する方法であり、ビームを走査あるいは基板を移動させることにより、スポットあるいはライン状の任意の加工が可能である。図２（Ｂ）では、レーザビームをライン状に照射しており、ビームを走査あるいは基板を移動させることにより、ライン状あるいは面状に加工することができる。 The CNT aggregate substrate in FIG. 1 (A) is obtained by directly attaching a CNT aggregate 12 on a substrate 11, and in FIG. 1 (B), it is attached via an insert material 13 such as a brazing material or an adhesive. It is a thing. FIG. 2 schematically shows a state in which the laser is irradiated. In FIG. 2A, a circular beam emitted from a laser oscillator 21 is focused by a lens 22 and spot-irradiated onto a CNT aggregate substrate. By scanning the beam or moving the substrate, a spot or line shape is obtained. Arbitrary processing is possible. In FIG. 2B, the laser beam is irradiated in a line shape, and the beam can be processed into a line shape or a surface shape by scanning or moving the substrate.
本発明による、基板上に露出状態で付着させたカーボンナノチューブ集合体にレーザを照射することによって、カーボンナノチューブを毛羽立たせ、電子放出特性を向上させることができる。 By irradiating the aggregate of carbon nanotubes adhered in an exposed state on the substrate according to the present invention, the carbon nanotubes can be fluffed and the electron emission characteristics can be improved.
アーク放電法を用いて生成した高純度カーボンナノチューブ１ｍｇをメチルアルコール１０ｍｌに加え、超音波を照射して分散させた。 1 mg of high-purity carbon nanotubes produced using the arc discharge method was added to 10 ml of methyl alcohol and dispersed by irradiating ultrasonic waves.
基板にはφ１０ｍｍ×１０ｍｍＬの円柱のＳＵＳ３０４板を用いた。 A cylindrical SUS304 plate having a diameter of 10 mm × 10 mmL was used as the substrate.
上記のカーボンナノチューブ分散液をスプレーノズルを用いて基板に散布し、自然乾燥させた。カーボンナノチューブの膜厚は約５μｍであった。
The above carbon nanotube dispersion liquid was sprayed on the substrate using a spray over the nozzle, and air-dried. The film thickness of the carbon nanotube was about 5 μm.
このカーボンナノチューブ付着面の電子顕微鏡写真を図４に示す。 An electron micrograph of the carbon nanotube adhesion surface is shown in FIG.
散布のままにおいてはＣＮＴ同士が密着しあって束状になり、全体としては滑らかなだまとなって寝た状態になっていることがわかる。 It can be seen that the CNTs are in close contact with each other as they are spread, forming a bundle, and as a whole, the CNTs are in a state of falling asleep.
このカーボンナノチューブ集合体が付着している基板上に波長５３２ｎｍ、エネルギー密度３００〜５００ｍＪ／ｃｍ2のライン状パルスＹＡＧレーザをラップなしに全面に照射した。図５に示すようにだまがなくなり、ＣＮＴ同士が解されて、ＣＮＴ端部の毛羽立ちも見られるようになっている。 The entire surface was irradiated with a line-shaped pulse YAG laser having a wavelength of 532 nm and an energy density of 300 to 500 mJ / cm 2 without wrapping on the substrate on which the carbon nanotube aggregate was adhered. As shown in FIG. 5, the fool is lost, the CNTs are disassembled, and fluffing at the end of the CNTs can be seen.
図６は、前記レーザ照射前後のＣＮＴ膜基板の電子放出特性を調べた結果である。レーザ照射による電子放出特性の向上効果はあきらかである。照射前の電子放出特性は悪い結果であるが、照射後にはおよそ３Ｖ／μｍの電界強度にて電流密度１０ｍＡ／ｃｍ2が得られている。これは非常に低い電界値であり優れた電子放出特性と言える。図５の電子顕微鏡写真に示したようにＣＮＴ同士が解れ、繊維の端部が表面に毛羽立って、かつ全体として均一である効果により得られていると考えられる。 FIG. 6 shows the results of examining the electron emission characteristics of the CNT film substrate before and after the laser irradiation. The effect of improving the electron emission characteristics by laser irradiation is obvious. Although the electron emission characteristic before irradiation is a bad result, a current density of 10 mA / cm 2 is obtained at an electric field strength of about 3 V / μm after irradiation. This is a very low electric field value and can be said to be excellent electron emission characteristics. As shown in the electron micrograph of FIG. 5, the CNTs are separated from each other, and it is considered that the end of the fiber is fluffed on the surface and is uniform as a whole.
以上より、本発明に係るＣＮＴ集合体接合基板を電子放出源として用いる場合、放出特性が高くかつ揃った任意の面積、形状の電極が可能なため、種々の電気機器または電子装置に設置することができる。 As described above, when the CNT assembly bonded substrate according to the present invention is used as an electron emission source, an electrode having an arbitrary area and shape with high emission characteristics is possible, so that it can be installed in various electric devices or electronic devices. Can do.
特にＶＦＤやＦＥＤなどは一様かつ高密度の大断面積電極が求められるため、容易に製造が可能となる。さらに高放出特性ため省電力、電源小型化（低電圧化が可能）等もできる。 In particular, VFD, FED, and the like require uniform and high-density large cross-sectional area electrodes, and therefore can be easily manufactured. Furthermore, because of its high emission characteristics, it is possible to save power and reduce the size of the power supply (lower voltage is possible).
１１…基板
１２…ＣＮＴ集合体
１３…ろう材接着剤等
２１…レーザ発振器
２２…レンズ
２３…ＣＮＴ基板
DESCRIPTION OF SYMBOLS 11 ... Substrate 12 ... CNT aggregate 13 ... Brazing material adhesive etc. 21 ... Laser oscillator 22 ... Lens 23 ... CNT substrate
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