JPH0792463B2 - Cathode using carbon nanotube - Google Patents
Cathode using carbon nanotubeInfo
- Publication number
- JPH0792463B2 JPH0792463B2 JP14555693A JP14555693A JPH0792463B2 JP H0792463 B2 JPH0792463 B2 JP H0792463B2 JP 14555693 A JP14555693 A JP 14555693A JP 14555693 A JP14555693 A JP 14555693A JP H0792463 B2 JPH0792463 B2 JP H0792463B2
- Authority
- JP
- Japan
- Prior art keywords
- cathode
- probe
- carbon nanotube
- sample
- stm
- 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.)
- Expired - Lifetime
Links
Description
【０００１】[0001]
【産業上の利用分野】本発明は走査トンネル電子顕微鏡
やトランジスタ等に用いられる極微細の陰極に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extremely fine cathode used for scanning tunneling electron microscopes, transistors and the like.
【０００２】[0002]
【従来の技術】フィジカル・レヴィユー・レター誌第４
９巻，第１号，第５７頁に記載されている走査トンネル
電子顕微鏡（Scanning Tunneling Microscopy; 以下、
ＳＴＭと記す。）は極めて高分解能の観察手段であり、
原子レベルの観察が可能である。図２はＳＴＭの概略構
成図である。導電性のある試料２１に対して負に印加さ
れた探針２２が一定の距離以下に近づくと、探針２２と
試料２１の間にトンネル電流が流れる。トンネル電流は
探針２２と試料２１間の距離に対して指数関数的に変化
するため、この距離に対して非常に敏感である。探針２
２にはＸ，Ｙ，Ｚ方向の制御軸２３、２４、２５が取り
付けられており、それぞれの制御軸は圧電素子によって
駆動される。圧電素子は電圧によってその長さを変える
素子であり、圧電素子に電圧を印加することによって、
探針２２のＸ，Ｙ，Ｚ方向の位置をそれぞれ制御するこ
とができる。観察にあたっては、試料２１と探針２２の
間に一定の電圧の下で一定の電流が流れるようにしてお
き、Ｘ，Ｙ方向制御軸２３、２４に電圧を印加すること
によって探針２２を走査させる。このとき試料２１表面
の凹凸に応じて試料２１と探針２２間の距離が変わりト
ンネル電流が変化しようとするが、このトンネル電流を
一定に保つようＺ方向制御軸２５を駆動する圧電素子に
電圧を印加し試料２１と探針２２間の距離を一定に保
つ。このＺ方向制御軸２５を駆動する圧電素子に印加す
る電圧を位置の関数としてモニターすれば、試料２１表
面の形状を知ることができる。ＳＴＭはトンネル電流が
試料２１と探針２２間の距離に対して極めて敏感なこと
と、圧電素子を用いればオングストローム単位の位置の
制御が可能になることから、極めて高感度の観察手段で
ある。[Prior Art] Physical Review Letter No. 4
Volume 9, No. 1, p. 57, Scanning Tunneling Microscopy;
It is written as STM. ) Is an extremely high resolution observation means,
Observation at the atomic level is possible. FIG. 2 is a schematic configuration diagram of the STM. When the probe 22 negatively applied to the conductive sample 21 approaches a certain distance or less, a tunnel current flows between the probe 22 and the sample 21. Since the tunnel current changes exponentially with respect to the distance between the probe 22 and the sample 21, it is very sensitive to this distance. Probe 2
The X-, Y-, and Z-direction control shafts 23, 24, and 25 are attached to 2 and each control shaft is driven by a piezoelectric element. A piezoelectric element is an element that changes its length depending on the voltage, and by applying a voltage to the piezoelectric element,
The position of the probe 22 in the X, Y and Z directions can be controlled respectively. In the observation, a constant current is made to flow between the sample 21 and the probe 22 under a constant voltage, and the probe 22 is scanned by applying a voltage to the X and Y direction control shafts 23 and 24. Let At this time, the distance between the sample 21 and the probe 22 changes according to the unevenness of the surface of the sample 21, and the tunnel current tends to change. However, voltage is applied to the piezoelectric element that drives the Z-direction control shaft 25 so as to keep this tunnel current constant. Is applied to keep the distance between the sample 21 and the probe 22 constant. By monitoring the voltage applied to the piezoelectric element that drives the Z-direction control shaft 25 as a function of position, the shape of the surface of the sample 21 can be known. The STM is an extremely high-sensitivity observation means because the tunnel current is extremely sensitive to the distance between the sample 21 and the probe 22 and the position can be controlled in Angstrom units by using a piezoelectric element.
【０００３】[0003]
【発明が解決しようとする課題】ＳＴＭの分解能を上
げ、より鮮明な像を得るためには、探針２２の先ができ
るだけ鋭いことが望ましい。ＳＴＭの探針２２はプラチ
ナ−イリジウムの合金やタングステン等の金属を電界研
磨によって削ることによって得られる。しかしその先端
の直径は最小で５０ｎｍ程度であり、原子等の被観察対
象と比べると大きすぎるという欠点があった。このＳＴ
Ｍの探針の例に見られるように、原子レベルの極微細な
電子源（陰極）は従来得られていなかった。本発明は、
前記ＳＴＭの探針等に用いることによって、従来の性能
を大幅に向上させることのできる極微細な陰極を提供す
ることを目的とする。In order to increase the STM resolution and obtain a clearer image, it is desirable that the tip of the probe 22 be as sharp as possible. The STM probe 22 is obtained by scraping a metal such as a platinum-iridium alloy or tungsten by electropolishing. However, the diameter of the tip is about 50 nm at the minimum, which is disadvantageous in that it is too large compared to the observed object such as an atom. This ST
As can be seen from the example of the M probe, an atom level electron source (cathode) has not been obtained in the past. The present invention is
It is an object of the present invention to provide an extremely fine cathode which can greatly improve the conventional performance by using it for the probe of the STM.
【０００４】[0004]
【課題を解決するための手段】本発明は、カーボンナノ
チューブの先端部が円錐状に細って閉じられ、他端には
電圧端子が具備されてなることを特徴とするカーボンナ
ノチューブを用いた陰極である。DISCLOSURE OF THE INVENTION The present invention is a cathode using carbon nanotubes, characterized in that the tip of carbon nanotube is narrowly conically closed and the other end is provided with a voltage terminal. is there.
【０００５】[0005]
【作用】カーボンナノチューブは、固体物理第２７巻，
第６号，第４４１頁に記載されているようにナノメート
ルサイズの黒鉛の極微細管で、金属または半導体の性質
を持つ導電体である。またカーボンナノチューブを構成
する炭素の六員環の一部を五員環で置きかえると、カー
ボンナノチューブは円錐状に細り先端が閉じる。この先
端の直径は１ｎｍから数ｎｍ程度であり、極めて細くす
ることができる。従って、カーボンナノチューブの先端
を閉じ、他端に電極を設けることで、極微細な陰極を得
ることができる。[Function] Carbon nanotube is a solid physics volume 27,
As described in No. 6, page 441, it is a nanometer-sized graphite ultrafine tube, which is a conductor having the properties of metal or semiconductor. When part of the carbon six-membered ring constituting the carbon nanotube is replaced with a five-membered ring, the carbon nanotube becomes conical and the tip is closed. The diameter of this tip is about 1 nm to several nm, and can be extremely thin. Therefore, an extremely fine cathode can be obtained by closing the tip of the carbon nanotube and providing the electrode at the other end.
【０００６】[0006]
【実施例】次に本発明の実施例について説明する。本実
施例では、カーボンナノチューブを用いた陰極をＳＴＭ
の探針に用いた場合について述べる。図１は被観察物で
ある試料１１を観察するＳＴＭの概略構成図である。探
針としてカーボンナノチューブ陰極１２がある。このカ
ーボンナノチューブ陰極１２は、太い部分の直径が３０
ｎｍで先端の直径は２ｎｍであり、金属的な導電体であ
る。カーボンナノチューブ陰極１２は、金属からなる探
針台１３に取り付けられ、この探針台１３を通して電子
が供給される。本実施例では探針台１３には銅を用い
る。探針台１３の位置は、Ｘ，Ｙ，Ｚ方向制御軸１４，
１５，１６によって制御される。Ｘ，Ｙ，Ｚ方向制御軸
１４，１５，１６はそれぞれ圧電素子で駆動される。EXAMPLES Next, examples of the present invention will be described. In this embodiment, the cathode using the carbon nanotube is STM.
Described below is the case of using it for the probe. FIG. 1 is a schematic configuration diagram of an STM for observing a sample 11 which is an object to be observed. There is a carbon nanotube cathode 12 as a probe. The carbon nanotube cathode 12 has a thick portion with a diameter of 30.
It has a tip diameter of 2 nm in nm and is a metallic conductor. The carbon nanotube cathode 12 is attached to a probe base 13 made of metal, and electrons are supplied through the probe base 13. In this embodiment, copper is used for the probe base 13. The position of the probe base 13 is defined by the X, Y, Z direction control axes 14,
It is controlled by 15, 16. The X, Y and Z direction control shafts 14, 15 and 16 are driven by piezoelectric elements, respectively.
【０００７】試料１１とカーボンナノチューブ陰極１２
を十分接近させ、探針台１３を介してカーボンナノチュ
ーブ陰極１２に電圧を印加すると、カーボンナノチュー
ブ陰極１２先端から電子が放出され、トンネル電流が試
料１１との間に流れる。Ｘ，Ｙ方向制御軸１４，１５を
圧電素子を用いて動かし、カーボンナノチューブ陰極１
２を試料１１上に走査させる。このときトンネル電流が
一定になるようにＺ方向制御軸１６を駆動する圧電素子
の電圧を制御する。このトンネル電流は試料１１とカー
ボンナノチューブ陰極１２との距離によって決まるた
め、Ｚ方向制御軸１６を駆動する圧電素子の電圧の変動
は、試料表面の形状を極めて高精度に反映し、この電圧
を位置の関数としてプロットすることによって、試料１
１表面の形状を精度良く知ることができる。Sample 11 and carbon nanotube cathode 12
Are sufficiently brought close to each other and a voltage is applied to the carbon nanotube cathode 12 via the probe base 13, electrons are emitted from the tip of the carbon nanotube cathode 12, and a tunnel current flows between the carbon nanotube cathode 12 and the sample 11. The carbon nanotube cathode 1 is moved by moving the X and Y direction control shafts 14 and 15 using a piezoelectric element.
2 is scanned on the sample 11. At this time, the voltage of the piezoelectric element that drives the Z-direction control shaft 16 is controlled so that the tunnel current becomes constant. Since this tunnel current is determined by the distance between the sample 11 and the carbon nanotube cathode 12, fluctuations in the voltage of the piezoelectric element that drives the Z-direction control shaft 16 reflect the shape of the sample surface with extremely high accuracy, and this voltage By plotting as a function of
1 The shape of the surface can be known accurately.
【０００８】本実施例では、ＳＴＭの探針の先がカーボ
ンナノチューブで構成されているため極めて細い。ＳＴ
Ｍは通常原子レベルの構造を観察することを目的として
いるため、探針の先が原子の大きさと同じ程度であるこ
とは分解能を上げ、かつ鮮明な像を得るために極めて重
要である。以上のことから、本実施例を用いれば極微細
な陰極が得られ、それをＳＴＭの探針に用いることによ
って、解像度が高く鮮明な画像の原子レベルの観察が可
能となる。本実施例では、カーボンナノチューブを用い
た陰極をＳＴＭの探針として用いたが、トランジスタの
陰極等としても用いることができる。この場合、大きさ
だけでなく、先端が細いことに由来する電子の放出しや
すさからも大きな効果が期待できる。In this embodiment, since the tip of the STM probe is made of carbon nanotube, it is extremely thin. ST
Since M is usually aimed at observing the structure at the atomic level, it is extremely important that the tip of the probe is as large as the size of the atom in order to improve the resolution and obtain a clear image. From the above, an extremely fine cathode can be obtained by using this embodiment, and by using it for an STM probe, it is possible to observe a sharp image with high resolution at the atomic level. In this embodiment, the cathode using the carbon nanotube is used as the probe of the STM, but it can be used as the cathode of the transistor. In this case, a large effect can be expected not only from the size but also from the ease of emitting electrons due to the thin tip.
【０００９】[0009]
【発明の効果】以上説明したように、本発明では、カー
ボンナノチューブを用いて原子サイズまで先端のとがっ
た陰極が実現できる。このカーボンナノチューブ陰極
は、例えばＳＴＭの探針として利用でき、従来のものを
大きく上回る解像度が得られるという効果を有する。ま
たトランジスタの陰極として利用すれば、従来のものよ
り、より小さな電圧で動作するトランジスタが得られる
という効果も有する。As described above, according to the present invention, the carbon nanotube can be used to realize a cathode having a sharp tip up to the atomic size. This carbon nanotube cathode can be used, for example, as an STM probe, and has the effect of achieving a resolution far exceeding that of the conventional one. Further, when it is used as a cathode of a transistor, there is an effect that a transistor which operates at a smaller voltage than that of the conventional one can be obtained.
【図１】本発明による陰極を探針として用いたＳＴＭの
概略構成図である。FIG. 1 is a schematic configuration diagram of an STM using a cathode according to the present invention as a probe.
【図２】従来例による探針を用いたＳＴＭの概略構成図
である。FIG. 2 is a schematic configuration diagram of an STM using a probe according to a conventional example.
１１ 試料 １２ カーボンナノチューブ陰極 １３ 探針台 １４ Ｘ方向制御軸 １５ Ｙ方向制御軸 １６ Ｚ方向制御軸 ２１ 試料 ２２ 探針 ２３ Ｘ方向制御軸 ２４ Ｙ方向制御軸 ２５ Ｚ方向制御軸 11 sample 12 carbon nanotube cathode 13 probe base 14 X-direction control axis 15 Y-direction control axis 16 Z-direction control axis 21 sample 22 probe 23 X-direction control axis 24 Y-direction control axis 25 Z-direction control axis
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平６−283129（ＪＰ，Ａ) 個体物理、27［６］（1992）Ｐ．441− 447 Ｎａｔｕｒｅ、354（1991 Ｐ．56−58 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-283129 (JP, A) Solid Physics, 27 [6] (1992) P. 441-447 Nature, 354 (1991 P.56-58)
Claims (1)
に細って閉じられ、他端には電圧端子が具備されてなる
ことを特徴とするカーボンナノチューブを用いた陰極。1. A cathode using carbon nanotubes, characterized in that the tip of the carbon nanotube is narrowly conically closed and the other end is provided with a voltage terminal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14555693A JPH0792463B2 (en) | 1993-05-25 | 1993-05-25 | Cathode using carbon nanotube |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14555693A JPH0792463B2 (en) | 1993-05-25 | 1993-05-25 | Cathode using carbon nanotube |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06331309A JPH06331309A (en) | 1994-12-02 |
| JPH0792463B2 true JPH0792463B2 (en) | 1995-10-09 |
Family
ID=15387897
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14555693A Expired - Lifetime JPH0792463B2 (en) | 1993-05-25 | 1993-05-25 | Cathode using carbon nanotube |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0792463B2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU5777096A (en) * | 1995-06-12 | 1997-01-09 | Ecole Polytechnique Federale De Lausanne | Electron source and applications of the same |
| DE69728410T2 (en) | 1996-08-08 | 2005-05-04 | William Marsh Rice University, Houston | MACROSCOPICALLY MANIPULATED DEVICES MANUFACTURED FROM NANOROE ASSEMBLIES |
| US6683783B1 (en) | 1997-03-07 | 2004-01-27 | William Marsh Rice University | Carbon fibers formed from single-wall carbon nanotubes |
| EP1054249B1 (en) | 1998-12-03 | 2007-03-07 | Daiken Chemical Co. Ltd. | Electronic device surface signal control probe and method of manufacturing the probe |
| US7279686B2 (en) * | 2003-07-08 | 2007-10-09 | Biomed Solutions, Llc | Integrated sub-nanometer-scale electron beam systems |
| JP2007242253A (en) * | 2006-03-06 | 2007-09-20 | Hitachi High-Technologies Corp | Sharpened carbon nanotube and electron source using it |
-
1993
- 1993-05-25 JP JP14555693A patent/JPH0792463B2/en not_active Expired - Lifetime
Non-Patent Citations (2)
| Title |
|---|
| Ｎａｔｕｒｅ、３５４（１９９１Ｐ．５６−５８ |
| 個体物理、２７［６（１９９２）Ｐ．４４１−４４７ |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06331309A (en) | 1994-12-02 |
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