JP2010006670A - Nanowire structure and method for producing the same - Google Patents

Nanowire structure and method for producing the same Download PDF

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JP2010006670A
JP2010006670A JP2008170618A JP2008170618A JP2010006670A JP 2010006670 A JP2010006670 A JP 2010006670A JP 2008170618 A JP2008170618 A JP 2008170618A JP 2008170618 A JP2008170618 A JP 2008170618A JP 2010006670 A JP2010006670 A JP 2010006670A
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nanowire
nanowire structure
gallium nitride
single crystal
gallium
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Tasuku Inoue
翼 井上
Satoshi Takeda
聡 竹田
Shigeo Ohira
重男 大平
Naoki Arai
直樹 新井
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Shizuoka University NUC
Nippon Light Metal Co Ltd
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Nippon Light Metal Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide nanowire structures with which the turn-on electric field is reduced, the current density is increased, and the emission of electrons is made uniform; and to provide a method for producing the same. <P>SOLUTION: A catalyst layer composed of Ni or Pt is formed on a gallium oxide single crystal substrate, and then, gallium nitride nanowires each in the form of a wire having a diameter of 5-200 nm and a length of 5-50 μm are formed by reacting trimethyl gallium and ammonia on the catalytic layer in a temperature range of 850-1,000°C by a CVD method. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、ナノワイヤ構造体およびその製造方法に関するものであり、詳しくは、ターンオン電界の低減、電流密度の向上、電子放出の均一化を達成したナノワイヤ構造体およびその製造方法に関するものである。本発明のナノワイヤ構造体は、次世代平面ディスプレイとして開発が進められているフィールドエミッションディスプレイ(ＦＥＤ)用の電子源等にとくに有用である。   The present invention relates to a nanowire structure and a method for manufacturing the same, and more particularly to a nanowire structure that achieves a reduction in turn-on electric field, an improvement in current density, and uniform electron emission, and a method for manufacturing the nanowire structure. The nanowire structure of the present invention is particularly useful as an electron source for a field emission display (FED), which is being developed as a next generation flat display.

従来、ＦＥＤは金属やシリコンを微細加工技術により円錐状に先鋭化した素子を電子源として用いていたが、製造コストや大画面化で問題があった。最近になって、カーボンナノチューブ(ＣＮＴ)がＦＥＤの電子源として優れた特性を有することが確認され、ＣＮＴを電子源とするＦＥＤも試作されるようになった。ＣＮＴを用いた電界放出電子源は、通常の熱電子源に比べ、加熱の必要がなく省エネ、高い電流密度、放出電子のエネルギー幅が狭いなど、高輝度の焦束電子の発生を揃えており、ＦＥＤのみならず真空マイクロエレクトロニクスの重要な電子源としての応用も図られている。しかしながら、ＣＮＴは寿命、耐久性に問題があり、長時間の使用できない欠点があった。   Conventionally, the FED has used a device in which metal or silicon is sharpened in a conical shape by a fine processing technique as an electron source. However, there has been a problem in manufacturing cost and enlargement of the screen. Recently, it has been confirmed that carbon nanotubes (CNT) have excellent characteristics as an electron source of FED, and FEDs using CNT as an electron source have also been prototyped. Field-emission electron sources using CNTs do not require heating as compared to ordinary thermionic sources, and energy generation, high current density, and narrow energy width of emitted electrons make generation of high-intensity focused electrons uniform. In addition to the FED, vacuum microelectronics are also being applied as important electron sources. However, CNT has problems in life and durability, and has a drawback that it cannot be used for a long time.

一方、金属、シリコン、ＣＮＴ以外の電子源として窒化ガリウム（ＧａＮ）も検討されている（例えば非特許文献１参照）。ＧａＮのナノワイヤから電子放出も確認されているが、非特許文献１に記載された技術の場合、ＧａＮナノワイヤはＳｉ基板上に作製されているため、放出した電子を蛍光体に照射したときなど発生する光を基板側から取り出せない。また、導電性基板として使うには抵抗も高いという問題もあった。これに対し、サファイアや石英などの透明な基板上にＧａＮナノワイヤを作製させることもできるが、この場合、基板は絶縁体であり、透明電極が必要になり、プロセスコストがかかるといった問題点があった。
Y.Inoue et al, phys. Stat. Sol. (c)4 (2007) 2366-2370. On the other hand, gallium nitride (GaN) has been studied as an electron source other than metal, silicon, and CNT (see, for example, Non-Patent Document 1). Electron emission from GaN nanowires has also been confirmed, but in the case of the technique described in Non-Patent Document 1, since GaN nanowires are fabricated on a Si substrate, they are generated when the emitted electrons are irradiated onto phosphors. Light cannot be extracted from the substrate side. Also, there is a problem that the resistance is high when used as a conductive substrate. On the other hand, GaN nanowires can be fabricated on a transparent substrate such as sapphire or quartz. However, in this case, the substrate is an insulator, and a transparent electrode is required, which increases the process cost. It was.
Y. Inoue et al, phys. Stat. Sol. (C) 4 (2007) 2366-2370.

本発明は、上記課題を解決するためになされたもので、金属、シリコン、カーボン系材料にかわる電子源として電子親和力が比較的小さく、化学的および機械的に安定であることから電界電子放出材料として適し、ターンオン電界の低減、電流密度の向上、電子放出の均一化を達成できるナノワイヤ構造体およびその製造方法を提供することを目的とする。   The present invention has been made to solve the above-described problems, and has a relatively low electron affinity as an electron source for metals, silicon, and carbon-based materials, and is chemically and mechanically stable. An object of the present invention is to provide a nanowire structure that can achieve a reduction in turn-on electric field, an improvement in current density, and uniform emission of electrons, and a method for manufacturing the same.

本発明は、以下のとおりである。
１．酸化ガリウム単結晶基板上に、径が５ｎｍ〜２００ｎｍ、長さが５μｍ〜５０μｍのワイヤ状の形態をした窒化ガリウムナノワイヤを形成してなるナノワイヤ構造体。
２．前記窒化ガリウムナノワイヤを形成する前記酸化ガリウム単結晶基板の結晶方位が、（１００）面であることを特徴とする前記１に記載のナノワイヤ構造体。
３．電圧印加によりターンオン電界強度が３〜４Ｖ／μｍの電子放出特性を有するエミッタに用いられることを特徴とする前記１または２に記載のナノワイヤ構造体。
４．電圧印加により前記窒化ガリウムナノワイヤ全体から均一に電界放射することを特徴とする前記１〜３のいずれかに記載のナノワイヤ構造体。
５．酸化ガリウム単結晶基板上に、ＮｉまたはＰｔからなる触媒層を形成し、前記触媒層上でトリメチルガリウムおよびアンモニアをＣＶＤ法により８５０〜１０００℃の温度範囲で反応させ、径が５ｎｍ〜２００ｎｍ、長さが５μｍ〜５０μｍのワイヤ状の形態をした窒化ガリウムナノワイヤを形成することを特徴とするナノワイヤ構造体の製造方法。
６．前記触媒層の厚さが２ｎｍ〜５ｎｍであることを特徴とする前記５に記載のナノワイヤ構造体の製造方法。 The present invention is as follows.
1. A nanowire structure in which a gallium nitride nanowire having a wire shape with a diameter of 5 nm to 200 nm and a length of 5 μm to 50 μm is formed on a gallium oxide single crystal substrate.
2. 2. The nanowire structure according to 1 above, wherein a crystal orientation of the gallium oxide single crystal substrate forming the gallium nitride nanowire is a (100) plane.
3. 3. The nanowire structure according to 1 or 2, which is used for an emitter having an electron emission characteristic with a turn-on electric field strength of 3 to 4 V / μm by applying a voltage.
4). 4. The nanowire structure according to any one of 1 to 3, wherein the electric field is uniformly emitted from the entire gallium nitride nanowire by voltage application.
5). A catalyst layer made of Ni or Pt is formed on a gallium oxide single crystal substrate, trimethylgallium and ammonia are reacted on the catalyst layer by a CVD method in a temperature range of 850 to 1000 ° C., and the diameter is 5 nm to 200 nm. A method for producing a nanowire structure, comprising forming a gallium nitride nanowire having a wire shape with a thickness of 5 μm to 50 μm.
6). 6. The method for producing a nanowire structure according to 5, wherein the catalyst layer has a thickness of 2 nm to 5 nm.

本発明によれば、酸化ガリウム単結晶基板上に径が５ｎｍ〜２００ｎｍ、長さが５μｍ〜５０μｍのワイヤ状の形態をした窒化ガリウムナノワイヤを形成することで、金属、シリコン、カーボン系材料にかわる電子源として電子親和力が比較的小さく、化学的および機械的に安定であることから電界電子放出材料として適し、ターンオン電界の低減、電流密度の向上、電子放出の均一化を達成したナノワイヤ構造体およびその製造方法を提供することができる。
とくに、本発明のナノワイヤ構造体は、非特許文献１におけるＳｉ基板を用いた場合に比べ、ターンオン電界強度を低減させることができた。これは、電界電子放出特性の向上に効果があるだけでなく、ＧａＮナノワイヤをデバイス化する際、酸化ガリウムは透明導電性基板であるため、電極作製などの製造プロセス、および発光効率の観点からも効果があると考えられる。 According to the present invention, a gallium nitride nanowire having a wire shape with a diameter of 5 nm to 200 nm and a length of 5 μm to 50 μm is formed on a gallium oxide single crystal substrate, thereby changing to a metal, silicon, or carbon-based material. A nanowire structure that is suitable as a field electron emission material due to its relatively low electron affinity as an electron source and is chemically and mechanically stable, achieving a reduced turn-on electric field, improved current density, and uniform electron emission A manufacturing method thereof can be provided.
In particular, the nanowire structure of the present invention was able to reduce the turn-on electric field strength as compared with the case where the Si substrate in Non-Patent Document 1 was used. This is not only effective in improving the field electron emission characteristics, but also when manufacturing GaN nanowires as a device, since gallium oxide is a transparent conductive substrate, from the viewpoint of manufacturing processes such as electrode fabrication and luminous efficiency. It is considered effective.

以下、本発明をさらに詳細に説明する。   Hereinafter, the present invention will be described in more detail.

（酸化ガリウム単結晶基板）
本発明の発光素子における基板は、酸化ガリウム(β−Ｇａ2Ｏ3)単結晶を用いる。β−Ｇａ2Ｏ3単結晶は、フローティングゾーン(ＦＺ法)や引上げ(ＣＺ法)などで作製されるが、るつぼを用いないＦＺ法で作製する方法が高品質の単結晶が得られるので好ましい。ＦＺ法で得られた単結晶を切断、研磨して表面を鏡面にし、例えば厚さ０．４ｍｍほどのウエハとする。このときの結晶方位は研磨が容易で製造しやすい(１００)面とするのがよい。ＦＺ法で作製したβ−Ｇａ2Ｏ3単結晶は、無色透明であり、光学的透過率はおよそ80％ほどであり、光吸収端はおよそ２６０ｎｍである。β−Ｇａ2Ｏ3単結晶は、添加元素なしでも作製する雰囲気による酸素欠損から発生した電子がキャリアとなって導電性を有するが、さらに導電性を向上させるために、Ｓｉ、Ｇｅ、ＳｎおよびＡｌから選択された少なくとも一種の元素を添加してなることが好ましい。これらドーピングする元素量は、β−Ｇａ2Ｏ3単結晶に対し、２０〜１００ｐｐｍが好ましい。 (Gallium oxide single crystal substrate)
A gallium oxide (β-Ga 2 O 3 ) single crystal is used for the substrate in the light-emitting element of the present invention. β-Ga 2 O 3 single crystal is produced in a floating zone (FZ method) or pulling up (CZ method), but a method produced by FZ method without using a crucible is preferable because a high quality single crystal is obtained. . A single crystal obtained by the FZ method is cut and polished to give a mirror surface, for example, a wafer having a thickness of about 0.4 mm. The crystal orientation at this time is preferably a (100) plane that is easy to polish and easy to manufacture. The β-Ga 2 O 3 single crystal produced by the FZ method is colorless and transparent, the optical transmittance is about 80%, and the light absorption edge is about 260 nm. In the β-Ga 2 O 3 single crystal, electrons generated from oxygen vacancies in an atmosphere produced without an additive element become carriers and have conductivity, but in order to further improve conductivity, Si, Ge, Sn and It is preferable to add at least one element selected from Al. The amount of these doping elements is preferably 20 to 100 ppm with respect to the β-Ga 2 O 3 single crystal.

（窒化ガリウムナノワイヤの形成）
本発明における窒化ガリウムナノワイヤは、Vapor-Liquid-Solid（VLS）成長により形成するのが適している。この成長モードは、成長速度が非常に早いので、高アスペクト比を得るのに適した作製方法であると言える。
具体的には、本発明における窒化ガリウムナノワイヤは、酸化ガリウム単結晶基板上に、ＮｉまたはＰｔからなる触媒層を形成し、前記触媒層上でトリメチルガリウムおよびアンモニアをＣＶＤ法により８５０〜１０００℃の温度範囲で反応させる工程を経て製造することができる。 (Formation of gallium nitride nanowires)
The gallium nitride nanowire in the present invention is suitably formed by Vapor-Liquid-Solid (VLS) growth. This growth mode can be said to be a production method suitable for obtaining a high aspect ratio because the growth rate is very high.
Specifically, in the gallium nitride nanowire in the present invention, a catalyst layer made of Ni or Pt is formed on a gallium oxide single crystal substrate, and trimethyl gallium and ammonia are formed on the catalyst layer at 850 to 1000 ° C. by a CVD method. It can manufacture through the process made to react in a temperature range.

ＮｉまたはＰｔからなる触媒層の形成方法としては、一般的な真空蒸着法、スパッタリング、イオンプレーティング法を採用することができる。
窒化ガリウムナノワイヤの径を細くし、かつアスペクト比を高め、電界電子放出特性を向上させるといった観点から、触媒層の厚さは、という理由から、２ｎｍ〜５ｎｍであることが好ましい。 As a method for forming the catalyst layer made of Ni or Pt, a general vacuum deposition method, sputtering, or ion plating method can be employed.
From the viewpoints of reducing the diameter of the gallium nitride nanowire, increasing the aspect ratio, and improving the field electron emission characteristics, the thickness of the catalyst layer is preferably 2 nm to 5 nm.

次に、触媒層上でトリメチルガリウム（ＴＭＧ）およびアンモニアをＣＶＤ法により８５０〜１０００℃、好ましくは８８０〜９２０℃の温度範囲で反応させ、本発明における窒化ガリウムナノワイヤを形成する。上記温度以外のＣＶＤ法の条件として、例えばＴＭＧのキャリアガスとしてＨ2を使用し、成長圧力として１〜１０Ｔｏｒｒ等の条件が好適である。
なお、前記温度が８５０℃未満であると、窒化ガリウムナノワイヤの径が大きくなり、逆に１０００℃を超えると、窒化ガリウムナノワイヤが成長しなくなり、好ましくない。 Next, trimethylgallium (TMG) and ammonia are reacted on the catalyst layer by a CVD method in a temperature range of 850 to 1000 ° C., preferably 880 to 920 ° C., to form the gallium nitride nanowire in the present invention. As the conditions of the CVD method other than the above temperature, for example, H 2 is used as a TMG carrier gas, and a growth pressure of 1 to 10 Torr is suitable.
When the temperature is lower than 850 ° C., the diameter of the gallium nitride nanowire increases. Conversely, when the temperature exceeds 1000 ° C., the gallium nitride nanowire does not grow, which is not preferable.

窒化ガリウムナノワイヤの密度は、触媒層の種類（Ｎｉ,Ｐｔ）、および厚さを変えることで制御できる。
また、窒化ガリウムナノワイヤの径および長さは、触媒層の種類および厚さを調整することで制御できる。 The density of the gallium nitride nanowire can be controlled by changing the type (Ni, Pt) and thickness of the catalyst layer.
Moreover, the diameter and length of the gallium nitride nanowire can be controlled by adjusting the type and thickness of the catalyst layer.

このようにして製造される本発明のナノワイヤ構造体は、酸化ガリウム単結晶基板上に、径が５ｎｍ〜２００ｎｍ、長さが５μｍ〜５０μｍ、さらに具体的には径が１０〜１００ｎｍ、長さが１０μｍ〜５０μｍのワイヤ状の形態をした窒化ガリウムナノワイヤが形成されてなる。窒化ガリウムナノワイヤは、アスペクト比が高いほうが好ましく、例えばアスペクト比（長さ／径）は、１００〜１０００、好ましくは２５０〜８００である。また、窒化ガリウムナノワイヤの密度は、１０12〜１０14本／ｍｍ2が好ましい。 The nanowire structure of the present invention thus manufactured has a diameter of 5 nm to 200 nm, a length of 5 μm to 50 μm, more specifically a diameter of 10 to 100 nm, and a length on a gallium oxide single crystal substrate. A gallium nitride nanowire having a wire shape of 10 μm to 50 μm is formed. The gallium nitride nanowire preferably has a high aspect ratio. For example, the aspect ratio (length / diameter) is 100 to 1000, preferably 250 to 800. The density of the gallium nitride nanowire is preferably 10 12 to 10 14 wires / mm 2 .

本発明のナノワイヤ構造体は、ターンオン電界強度を低減させることができ、電圧印加によるターンオン電界強度が３〜４Ｖ／μｍの電子放出特性を有するエミッタに好適に用いられる。また、本発明のナノワイヤ構造体は、電圧印加により窒化ガリウムナノワイヤ全体から均一に電界放射される特性を有する。   The nanowire structure of the present invention can reduce the turn-on electric field strength, and is suitably used for an emitter having electron emission characteristics with a turn-on electric field strength of 3 to 4 V / μm by voltage application. In addition, the nanowire structure of the present invention has a characteristic that electric field is radiated uniformly from the entire gallium nitride nanowire when a voltage is applied.

以下、本発明のナノワイヤ構造体の電界電子放出特性について、従来のＳｉ基板を用いた場合と比較しながら、以下の実施例で説明する。なお本発明は、以下の例に制限されるものではない。   Hereinafter, the field electron emission characteristics of the nanowire structure of the present invention will be described in the following examples, in comparison with the case of using a conventional Si substrate. Note that the present invention is not limited to the following examples.

実施例１
無添加のβ−Ｇａ2Ｏ3単結晶を育成しウエハ状に加工した。単結晶育成は、酸化ガリウム粉末(純度４Ｎ)を原料とし、静水圧プレスで成形した成形体を大気中１６００℃、１０時間で焼結し、この焼結体を原料棒としてＦＺ装置を用いて単結晶育成を行った。成長速度は７．５ｍｍ/ｈとし、雰囲気ガスにはドライエアを用いた。装置としては、市販の光ＦＺ装置（キャノンマシナリー社製商品名ｉＡｃｅ）を用いた。作製した単結晶を切断し、ＣＭＰ(化学機械)研磨により厚さ０．４ｍｍのウエハ状に加工した。この場合の研磨面の結晶方位は(１００)面であり、透過率はおよそ８０％、抵抗率は１．４３×１０-1Ωｃｍである。 Example 1
An additive-free β-Ga 2 O 3 single crystal was grown and processed into a wafer shape. Single crystal growth uses gallium oxide powder (purity 4N) as a raw material, and a molded body formed by isostatic pressing is sintered in the atmosphere at 1600 ° C. for 10 hours, and this sintered body is used as a raw material rod using an FZ apparatus. Single crystal growth was performed. The growth rate was 7.5 mm / h, and dry air was used as the atmospheric gas. As a device, a commercially available optical FZ device (trade name iAce manufactured by Canon Machinery Co., Ltd.) was used. The produced single crystal was cut and processed into a wafer having a thickness of 0.4 mm by CMP (chemical mechanical) polishing. Crystal orientation of the polished surface in this case is (100) plane, the transmittance of about 80%, the resistivity is 1.43 × 10 -1 Ωcm.

得られた酸化ガリウム単結晶基板上に、Ptを触媒として電子ビーム蒸着法によりおよそ５nmの触媒層を形成した。   On the obtained gallium oxide single crystal substrate, a catalyst layer of about 5 nm was formed by electron beam evaporation using Pt as a catalyst.

続いて、形成した触媒層上でトリメチルガリウムおよびアンモニアをＣＶＤ法により反応させた。このときの条件は、キャリアガスには水素を用い、チェンバ内圧力：５Torr、基板表面温度：９００℃、反応時間：６０分とした。   Subsequently, trimethylgallium and ammonia were reacted on the formed catalyst layer by a CVD method. The conditions at this time were such that hydrogen was used as the carrier gas, the chamber internal pressure: 5 Torr, the substrate surface temperature: 900 ° C., and the reaction time: 60 minutes.

このようにして得られた窒化ガリウムナノワイヤのＳＥＭ写真を図１に示す。
実施例１における窒化ガリウムナノワイヤの径は、５〜２０ｎｍ、長さは５〜１０μｍであり、ワイヤ状の形状をなし、平均密度は５×１０12本／ｍｍ2であった。 An SEM photograph of the gallium nitride nanowire thus obtained is shown in FIG.
The diameter of the gallium nitride nanowire in Example 1 was 5 to 20 nm, the length was 5 to 10 μm, the wire shape was formed, and the average density was 5 × 10 12 wires / mm 2 .

次に、実施例１のナノワイヤ構造体を用いて電界電子放出特性の測定を行った。測定装置の概要を図２に示す。
図２において、陰極としてのステンレス製の土台１０１上に試料１０（実施例１のナノワイヤ構造体）を設置し、土台１０１と陽極１０２との距離を０．９ｍｍとした。陽極１０２上に蛍光板１０３を設置し、さらにその上にＩＴＯ透明電極付きガラス板１０４を設置した。なお、陽極１０２の厚さは０．２ｍｍである。
７．６×１０-8Torrの真空下、０〜２．８ｋＶの電圧範囲で５Ｖ刻みで電流計１０５により電流値を測定した。その結果を図３（ａ）に示す。図３（ａ）から分かるように、１．３ｋＶにおいて電界電子放出を確認し、１．５ｋＶにおいて前記ＩＴＯ透明電極付きガラス板１０４を介した蛍光板１０３からの発光を肉眼で確認した。２．０ｋＶおよび２．８ｋＶ印加時の蛍光板１０３からの発光の様子を図３（ｂ）に示した。図３（ａ）の電流−電圧特性から、電流密度約３２μＡ/ｃｍ2、ターンオン電界強度約３Ｖ/μmで電界電子放出が得られたことがわかる。 また、試料全体から比較的均一性が高く電界電子放出しているのが確認された。 Next, the field electron emission characteristics were measured using the nanowire structure of Example 1. An outline of the measuring apparatus is shown in FIG.
In FIG. 2, the sample 10 (the nanowire structure of Example 1) was placed on a stainless steel base 101 as a cathode, and the distance between the base 101 and the anode 102 was 0.9 mm. A fluorescent plate 103 was placed on the anode 102, and a glass plate 104 with an ITO transparent electrode was further placed thereon. The thickness of the anode 102 is 0.2 mm.
The current value was measured by the ammeter 105 in increments of 5 V in a voltage range of 0 to 2.8 kV under a vacuum of 7.6 × 10 −8 Torr. The result is shown in FIG. As can be seen from FIG. 3A, field electron emission was confirmed at 1.3 kV, and light emission from the fluorescent plate 103 through the glass plate 104 with the ITO transparent electrode was confirmed with the naked eye at 1.5 kV. FIG. 3B shows the state of light emission from the fluorescent plate 103 when 2.0 kV and 2.8 kV are applied. From the current-voltage characteristics of FIG. 3A, it can be seen that field electron emission was obtained at a current density of about 32 μA / cm 2 and a turn-on field strength of about 3 V / μm. It was also confirmed that field electrons were emitted from the entire sample with relatively high uniformity.

比較例１
実施例１において、酸化ガリウム単結晶基板の替わりに、Ｓｉ基板を用いたこと以外は、実施例１を繰り返し、電界電子放出特性を測定した。図４（ａ）は、Ｓｉ基板上に作製した窒化ガリウムナノワイヤの光学顕微鏡写真であり、（ｂ）はＳＥＭ写真である（（ｂ）の上図は上面からの写真であり、下図は断面方向からみた写真である）。直径２０〜１００ｎｍ、長さ約２０μｍの窒化ガリウムナノワイヤが形成されているのが観察された。
比較例１のナノワイヤ構造体の電界電子放出特性を実施例１と同様な方法で測定した結果、図５に示すように、陽極間距離０．８ｍｍとし、５×１０-5Torrの真空下で、３．２ｋＶあたりから電流が流れ始めており、電界強度としては約４Ｖ/μmであることがわかった。この値は、実施例１のナノワイヤ構造体のターンオン電界強度である約３Ｖ/μmに比べると高い結果となっており、酸化ガリウム単結晶基板上に窒化ガリウムナノワイヤを形成してなるナノワイヤ構造体の電界電子放出特性の方が良好であることがわかる。 Comparative Example 1
In Example 1, Example 1 was repeated except that a Si substrate was used instead of the gallium oxide single crystal substrate, and field electron emission characteristics were measured. 4A is an optical micrograph of a gallium nitride nanowire fabricated on a Si substrate, FIG. 4B is an SEM photograph (the upper diagram in FIG. 4B is a photograph from the top, and the lower diagram is the cross-sectional direction) It is a photograph taken from the viewpoint.) It was observed that gallium nitride nanowires having a diameter of 20 to 100 nm and a length of about 20 μm were formed.
The field electron emission characteristics of the nanowire structure of Comparative Example 1 were measured by the same method as in Example 1. As a result, as shown in FIG. 5, the distance between the anodes was 0.8 mm and the vacuum was 5 × 10 −5 Torr. It was found that current started to flow from around 3.2 kV and the electric field strength was about 4 V / μm. This value is higher than the turn-on field strength of about 3 V / μm, which is the turn-on field strength of the nanowire structure of Example 1, and the nanowire structure formed by forming the gallium nitride nanowire on the gallium oxide single crystal substrate. It can be seen that the field electron emission characteristics are better.

本発明のナノワイヤ構造体は、次世代平面ディスプレイとして開発が進められているフィールドエミッションディスプレイ(ＦＥＤ)用の電子源等にとくに有用である。   The nanowire structure of the present invention is particularly useful as an electron source for a field emission display (FED), which is being developed as a next generation flat display.

実施例１で形成した窒化ガリウムナノワイヤのＳＥＭ写真である。2 is a SEM photograph of the gallium nitride nanowire formed in Example 1. 実施例１で用いた電界電子放出特性の測定装置の概要を説明する図である。It is a figure explaining the outline | summary of the measuring apparatus of the field electron emission characteristic used in Example 1. FIG. （ａ）は実施例１のナノワイヤ構造体の電界電子放出特性を示すグラフであり、（ｂ）は、２．０ｋＶおよび２．８ｋＶ印加時の蛍光板からの発光の様子を示す写真である。(A) is a graph which shows the field electron emission characteristic of the nanowire structure of Example 1, (b) is a photograph which shows the mode of the light emission from the fluorescent screen at the time of 2.0 kV and 2.8 kV application. （ａ）は、比較例１のＳｉ基板上に作製した窒化ガリウムナノワイヤの光学顕微鏡写真であり、（ｂ）はＳＥＭ写真である。(A) is an optical microscope photograph of the gallium nitride nanowire produced on the Si substrate of Comparative Example 1, and (b) is an SEM photograph. 比較例１のナノワイヤ構造体の電界電子放出特性を示すグラフである。6 is a graph showing field electron emission characteristics of the nanowire structure of Comparative Example 1.

符号の説明Explanation of symbols

１０ 試料
１０１ 土台
１０２ 陽極
１０３ 蛍光板
１０４ ＩＴＯ透明電極付きガラス板
１０５ 電流計 10 Sample 101 Base 102 Anode 103 Fluorescent Plate 104 Glass Plate with ITO Transparent Electrode 105 Ammeter

Claims (6)

酸化ガリウム単結晶基板上に、径が５ｎｍ〜２００ｎｍ、長さが５μｍ〜５０μｍのワイヤ状の形態をした窒化ガリウムナノワイヤを形成してなるナノワイヤ構造体。   A nanowire structure in which a gallium nitride nanowire having a wire shape with a diameter of 5 nm to 200 nm and a length of 5 μm to 50 μm is formed on a gallium oxide single crystal substrate. 前記窒化ガリウムナノワイヤを形成する前記酸化ガリウム単結晶基板の結晶方位が、（１００）面であることを特徴とする請求項１に記載のナノワイヤ構造体。   2. The nanowire structure according to claim 1, wherein a crystal orientation of the gallium oxide single crystal substrate forming the gallium nitride nanowire is a (100) plane. 電圧印加によりターンオン電界強度が３〜４Ｖ／μｍの電子放出特性を有するエミッタに用いられることを特徴とする請求項１または２に記載のナノワイヤ構造体。   3. The nanowire structure according to claim 1, wherein the nanowire structure is used for an emitter having an electron emission characteristic with a turn-on electric field strength of 3 to 4 V / μm by voltage application. 電圧印加により前記窒化ガリウムナノワイヤ全体から均一に電界放射することを特徴とする請求項１〜３のいずれかに記載のナノワイヤ構造体。   The nanowire structure according to any one of claims 1 to 3, wherein electric field is uniformly emitted from the entire gallium nitride nanowire by voltage application. 酸化ガリウム単結晶基板上に、ＮｉまたはＰｔからなる触媒層を形成し、前記触媒層上でトリメチルガリウムおよびアンモニアをＣＶＤ法により８５０〜１０００℃の温度範囲で反応させ、径が５ｎｍ〜２００ｎｍ、長さが５μｍ〜５０μｍのワイヤ状の形態をした窒化ガリウムナノワイヤを形成することを特徴とするナノワイヤ構造体の製造方法。   A catalyst layer made of Ni or Pt is formed on a gallium oxide single crystal substrate, trimethylgallium and ammonia are reacted on the catalyst layer by a CVD method in a temperature range of 850 to 1000 ° C., and the diameter is 5 nm to 200 nm. A method for producing a nanowire structure, comprising forming a gallium nitride nanowire having a wire shape with a thickness of 5 μm to 50 μm. 前記触媒層の厚さが２ｎｍ〜５ｎｍであることを特徴とする請求項５に記載のナノワイヤ構造体の製造方法。   The method for producing a nanowire structure according to claim 5, wherein the catalyst layer has a thickness of 2 nm to 5 nm.
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105040096A (en) * 2015-06-25 2015-11-11 广东工业大学 Novel spiral GaN monocrystal nanowire and preparation method thereof
CN106319557A (en) * 2015-07-07 2017-01-11 中国科学院大连化学物理研究所 Photoelectrochemistry water decomposition GaN:ZnO photo-anode preparing method
CN107628637A (en) * 2017-08-14 2018-01-26 南京大学 A kind of method for preparing III oxide and nitride nano post
US11239391B2 (en) 2017-04-10 2022-02-01 Norwegian University Of Science And Technology (Ntnu) Nanostructure

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105040096A (en) * 2015-06-25 2015-11-11 广东工业大学 Novel spiral GaN monocrystal nanowire and preparation method thereof
CN106319557A (en) * 2015-07-07 2017-01-11 中国科学院大连化学物理研究所 Photoelectrochemistry water decomposition GaN:ZnO photo-anode preparing method
US11239391B2 (en) 2017-04-10 2022-02-01 Norwegian University Of Science And Technology (Ntnu) Nanostructure
EP3610518B1 (en) * 2017-04-10 2023-09-13 Norwegian University of Science and Technology (NTNU) Nanostructure
CN107628637A (en) * 2017-08-14 2018-01-26 南京大学 A kind of method for preparing III oxide and nitride nano post

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