この作業は、プロジェクトの最も 105-2221-E-001-011-MY3 と最も 105-2622-8-002-001 省の科学と技術、台湾、によって資金を供給の資金を供給された研究センター応用科学、中国科学院の焦点を絞ったプロジェクトによって部分で支えられました台湾。

1. 個々 の 2 D 素材 (MoS2と WS2) の成長
<ol><li>
スパッタ法を用いた遷移金属蒸着
	<ol>
<li>きれいな 2 × 2 cm2サファイア基板は、洗練された遷移金属成膜用スパッタリング装置のターゲット側のサンプル ホルダーに配置されます。サファイア基板、サファイアの高温で原子フラット表面の化学的安定性により選択します。</li>
		<li>スパッタ室に続いて拡散ポンプ機械式ポンプを使用して順に 3 x 10-6 torr までダウン ポンプです。</li>
		<li>スパッタリング装置に Ar ガスを注入し、40 mL/分マスフロー コント ローラー (MFC) を使用してガスの流れを保ちます。</li>
		<li>手動圧力制御弁による 5 x 10-2 torr で燃焼圧力を保持し、Ar プラズマを点火します。・ w ・ 40 で出力電力を維持します。</li>
		<li>手動ホイール角度ポペット弁を使用して 5 × 10-3 torr まで燃焼室圧力が低下します。</li>
		<li>手動でサファイア基板と 2 インチの金属ターゲットの間シャッターを開き、金属析出を開始します。成膜中には、40 W で Mo および w. のためのスパッタ電力を維持する.背景の圧力は 40 mL/min Ar ガスの流れと 5 × 10-3 torr で保持されます。</li>
		<li>異なる厚みをもつ遷移金属膜スパッタ時間を制御します。薄い金属の厚さによるスパッタ回水晶振動子からの測定値より膜厚のよりよい制御を提供します。 注: MoS2と WS2現在の原稿で説明する方法を使用して育つの層数、中古蒸着 Mo および W の膜のスパッタの時に比例します。必要なレイヤー番号を持つ MoS2と WS2を取得する回をスパッタ法の決定は、異なるスパッタ時間サンプルの断面の高分解能透過電子顕微鏡 (HRTEM) 画像に基づいています。ただし、事前に堆積した Mo および W 膜が厚すぎる、Mo および W の酸化分離は平面の MoS2と WS2薄膜成長の代わりに、支配的な成長のメカニズムになります。したがって、スパッタリング時の層数の比例は TMDs 少数層に限定されます。MoS2現在原稿の成長条件、レイヤー番号は、MoS2フィルムがより少ない 10 層スパッタリング時刻に比例になります。スパッタリングの時間は半 5 層 MoS2の成長のための s。</li>
	</ol>
</li>
	<li>
遷移金属薄膜の硫化
	<ol>
<li>硫化の熱い炉の中心部に事前に堆積した遷移金属薄膜のサファイア基板を配置します。</li>
		<li>ガスの流れ、炉の加熱ゾーンから 2 cm の上流の硫黄 (S) 粉末を配置します。この位置に S パウダーの蒸発温度を 120 ° C 基板温度が 800 ° C に増加異なる遷移金属硫化 S 粉末の重量を正確に制御します。仕事で S 粉末重量は mo および w. の 1.0 g 1.5 g です。 注: 我々 は MoS2や材料ごとに硫黄の粉の量が異なるを使用した結果に基づき WS2映画の準備のための硫黄粉末量を定めます。</li>
		<li>0.7 torr で炉内圧力を維持します。硫化処理中に 130 mL/分 Ar ガスは、キャリアガスとして使用されました。</li>
		<li>硫黄の粉が完全に蒸発するまでランプ ランプ率が温度 20 ° C/分と常温から 40 分で 800 ° C の炉の温度は 800 ° c 温度を保ちます。その後、炉内温度を下げるためのヒーター電源がオフになって。室温から 800 ° C に到達する炉の約 30 に 40 分かかる</li>
	</ol>
</li>
	<li>488 nm レーザー15,16,17を使用してラマン スペクトル計測を実行します。2次元結晶15,16,17のレイヤー番号を確認する断面の高分解能電顕像を入手します。</li>
</ol>2. WS2/MoS2垂直単一ヘテロ構造の成長
注: このセクションは単一ヘテロ構造の MoS2の 5 層とサファイア層および WS2の 4 層から成るを作成する使用します。
<ol><li>手順 1.1 と同じ手順に従ってください。30 システム スパッタを用いたサファイア基板上ミズーリ フィルムを入金時間をスパッタリング s。</li>
	<li>1.2 MoS2の成長のためのステップとして硫化と同じ手順をに従ってミズーリ フィルムを sulfurize します。硫化処理後 MoS2の 5 つの層を取得します。</li>
	<li>手順 1.1 と同じ手順に従います。MoS2W フィルムを沈殿物/サファイア基板を用いた RF スパッタ装置 30 s 時間をスパッタリングします。</li>
	<li>ステップ 1.2 WS2の成長のための同じの硫化を手順 W フィルムを sulfurize します。WS2の 4 つの層は、硫化処理後 MoS2の上に取得されます。 注: 金属蒸着・硫化手順は個々 の素材と同じです。Mo および W 薄膜のスパッタリング回 MoS2層と WS2層の必要なレイヤーの数に応じて決定されます。ダブルやマルチ-ヘテロ-構造は、成長と同じ手順を繰り返すことによって確立できます。サンプル構造に応じて垂直方向ヘテロ構造における Tmd のシーケンスを変更もできます。</li>
</ol>3. フィルムの転送とデバイス作製手順
<ol><li>
2次元結晶膜の手順を転送する映画
	<ol>
<li>スピン コート poly(methyl methacrylate) 室温で映画全体をカバーする TMD フィルム上の 3 が値下がりしました。紡績工の 2 段階の回転速度が 10 秒の 500 rpm および 10 の 800 rpm s。硬化後 5 分の 120 ° C で、PMMA 膜厚は約 3 μ m です。</li>
		<li>(DI) の脱イオン水で満ちているペトリ皿に PMMA/顎関節症/サファイア サンプルを配置します。</li>
		<li>DI 水でピンセットを用いたサファイア基板から PMMA/顎関節症映画の一角をはがします。</li>
		<li>100 ° C にビーカーで 1 M KOH 水溶液 (14 g の KOH ペレットを 250 mL の水と混合) の 250 mL を加熱します。温水 KOH 水溶液でサンプルを移動し、映画は完全に基板から剥離まで PMMA/TMD フィルムを剥離を続けます。剥離では、約 1 分を完了する必要があります。</li>
		<li>KOH 溶液から PMMA/TMD フィルムをスクープする別のサファイア基板を使用します。フィルムをフィルムに島の残渣を洗浄する DI 水で満たされた 250 mL のビーカーに移動します。この段階では、PMMA/TMD フィルムとフィルムをスクープするサファイア基板との密着性は弱いです。したがって、映画デ ・ ディ ・水に浸漬後にサファイア基板からアタッチされます。</li>
		<li>3.1.4 - 3.1.5 の手順を繰り返して 3 回確認する新しい DI 水を使用して残島のほとんどがフィルムから削除されます。 注: TMD 層間密着性は TMDs サファイア基板よりもはるかに強いです。したがって、同じ転送手順は、個別 MoS2/WS2材料またはそのヘテロ構造のいずれかに適用できます。2次元結晶膜が完全に剥離、基板から剥離、MoS2/graphene ヘテロ構造前文書18で説明したのと同様であります。、映画の転送の目的に応じてこの手順に記載されている基板、または設定できますサファイア基板中古蒸着電極と SiO2/Si 基板 3.2 の手順で説明するよう。この目的のため、その他の基板を使用もできます。</li>
	</ol>
</li>
	<li>
2次元結晶トランジスタの作製。
	<ol>
<li>SiO2/Si 基板15,16,17の電極パターンを定義するのに標準写真平版を使用します。10 nm チタン (Ti) または 100 nm の金 (Au) のソース ・ ドレイン電極は 300 nm SiO2/p-type Si 基板上に作製しました。</li>
		<li>SiO2/Si 基板・ ディ ・水が入ったビーカーにソース/ドレイン電極加工し、3.1 の手順で用意して、PMMA/顎関節症映画の TMD 側に接続を浸します。</li>
		<li>フィルムは水の残留物を削除する、SiO2/Si 基板を接続した後、3 分間 100 ° C でサンプルを焼きます。</li>
		<li>PMMA の表面全体をカバーしよりしっかりと基板に取り付けられて映画を作る PMMA/TMD フィルム試料の 3 滴を滴下します。</li>
		<li>次のステップに移動する前に、少なくとも 8 時間のための電子乾燥キャビネットにサンプルを配置します。</li>
		<li>アセトンで 2 つの異なる 250 mL ビーカーを入力します。2 つの異なるビーカー PMMA の最上位のレイヤーを削除する, アセトン 50 と 10 分でいっぱいに順次の PMMA/TMD フィルム付けサンプルを浸します。</li>
		<li>標準光リソグラフィと反応性イオン エッチング15,16,17を使用してトランジスタのチャネルを定義します。背部ゲート MoS2 WS2/MoS2ヘテロ構造トランジスタ作製15,16,17.チャネル長とデバイスの幅は、それぞれ 5 と 150 μ m です。</li>
		<li>トランジスタ15,16,17の電流-電圧特性を測定するのにデュアル チャンネル システム sourcemeter の計測器を使用します。</li>
	</ol>
</li>
</ol>

<ol>
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Si や GaAs など従来の半導体材料と比較して、デバイス アプリケーション用 2 D 材料の利点は原子層数の非常に薄いボディとデバイス作製の可能性にあります。Si 業界が進出する場合、< 10 nm 技術ノード、Si フィン FET の高アスペクト比になるデバイス アーキテクチャの実用的なアプリケーションには適していません。したがって、2 D 素材は、その電子デバイス用 Si を交換する可能性があるの...

2次元結晶膜を取得する最も一般的な方法の 1 つは、バルク材料1,2,3,4、5からの機械的ピーリングを使用しています。高品質結晶の 2次元結晶膜ができますこのメソッドを使用して簡単に得られる、スケーラブルな 2 D 液晶は実用に不利であるが、このアプローチを通じて利用可能なありません。それは、化学気相成長法 (CVD) を使用すると、大面積で均一の 2次元結晶膜ができる準備6,7,8,9以前の出版物で実証されています。サファイア基板と同じ成長のサイクルを繰り返すことにより層数制御可能な MoS2膜グラフェンの直接成長はまた、CVD 成長技術10,11を使用して示されました。1 つの最近の出版物では、面内 WSe2/MoS2ヘテロ構造フレークもは、CVD 成長技術12を用いて作製しました。CVD 成長技術は有望なスケーラブルな 2次元結晶膜を提供することで、この成長の技術の主要な不利な点は異なった前駆体が異なる 2次元結晶を配置しなければならないこと。成長条件も異なる 2次元結晶によって異なります。この場合、需要増加する 2次元結晶ヘテロ構造成長のプロシージャはより複雑ななります。
CVD 成長法と比較して、事前に堆積した遷移金属薄膜の硫化は TMDs13,14似ていますが、はるかに簡単な成長のアプローチを提供しています。成長のプロシージャを含む金属蒸着と硫化手順だけ、ので成長と同じ手順で異なる TMDs を成長することが可能です。その一方で、2次元結晶の層数制御は、事前入金の遷移金属の厚さを変更することによって達成されるかもしれません。この場合、単一のレイヤーまで成長最適化と層数制御が異なる TMDs の必要成長機構の理解もこの法を用いた複雑な顎関節症ヘテロ構造の確立のため非常に重要です。
この紙、MoS2 WS2硫化手順続いて金属蒸着の同じような成長のプロシージャの下で膜が得られました。硫黄前約条件下で Mo 薄膜の硫化から得られた結果と 2 つの成長メカニズムは硫化手順15の間に観察されます。硫黄の十分な条件の下で硫化のプロシージャの後制服と層数制御可能な MoS2フィルムが得られます。サンプルは、硫黄欠乏条件下で硫化は、背景硫黄では、Mo 酸化物の分離・合体は初期の成長段階で支配的なメカニズムになりますよう完全な MoS2フィルムを形成できません。硫化手順15の後 MoS2のいくつかの層で覆われている Mo 酸化物クラスターのサンプルを取得します。順次金属蒸着と手順硫化、WS2/MoS2垂直方向ヘテロ構造単一の層に層数制御と15,16に用意できます。この手法を使用して、サンプルは 4 つの地域と 1 つのサファイア基板上得られた: (I) 空白のサファイア基板、(II) スタンドアロン MoS2、(III) WS2/MoS2ヘテロ構造、および (IV) スタンドアロン WS217.結果を示す成長技術が垂直 2次元結晶ヘテロ構造の確立のため有利であるし、選択成長が可能です。2次元結晶ヘテロ構造の強化されたデバイスのパフォーマンスは、2次元結晶の実用への第一歩がマークされます。

<table>
	<tbody>
		<tr>
			<td>RF sputtering system</td>
			<td>Kao Duen Technology</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Furnace for sulfurization</td>
			<td>Creating Nano Technologies</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Polymethyl methacrylate (PMMA)</td>
			<td>Microchem</td>
			<td>8110788</td>
			<td>Flammable</td>
		</tr>
		<tr>
			<td>KOH, &#62; 85%</td>
			<td>Sigma-Aldrich</td>
			<td>30603</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetone, 99.5%</td>
			<td>Echo Chemical</td>
			<td>CMOS110</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfur (S), 99.5%</td>
			<td>Sigma-Aldrich</td>
			<td>13803</td>
			<td></td>
		</tr>
		<tr>
			<td>Molybdenum (Mo), 99.95%</td>
			<td>Summit-Tech</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Tungsten (W), 99.95%</td>
			<td>Summit-Tech</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>C-plane Sapphire substrate</td>
			<td>Summit-Tech</td>
			<td>X171999</td>
			<td>(0001) &#177; 0.2 &#176; one side polished</td>
		</tr>
		<tr>
			<td>300 nm SiO2/Si substrate</td>
			<td>Summit-Tech</td>
			<td>2YCDDM</td>
			<td>P-type Si substrate, resistivity: 1-10 &#937; &#183; cm.</td>
		</tr>
		<tr>
			<td>Sample holder (sputtering system)</td>
			<td>Kao Duen Technology</td>
			<td>N/A</td>
			<td>Ceramic material</td>
		</tr>
		<tr>
			<td>Mechanical pump (sputtering system)</td>
			<td>Ulvac</td>
			<td>D-330DK</td>
			<td></td>
		</tr>
		<tr>
			<td>Diffusion pump (sputtering system)</td>
			<td>Ulvac</td>
			<td>ULK-06A</td>
			<td></td>
		</tr>
		<tr>
			<td>Mass flow controller</td>
			<td>Brooks</td>
			<td>5850E</td>
			<td>The maximum Argon flow is 400 mL/min</td>
		</tr>
		<tr>
			<td>Manual wheel Angle poppet valve</td>
			<td>King Lai</td>
			<td>N/A</td>
			<td>Vacuum range from 2500 ~1 &#215; 10-8 torr</td>
		</tr>
		<tr>
			<td>Raman measurement system</td>
			<td>Horiba</td>
			<td>Jobin Yvon LabRAM HR800</td>
			<td></td>
		</tr>
		<tr>
			<td>Transmission electron microscopy</td>
			<td>Fei</td>
			<td>Tecnai G2 F20</td>
			<td></td>
		</tr>
		<tr>
			<td>Petri dish</td>
			<td>Kwo Yi</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Tweezer</td>
			<td>Venus</td>
			<td>2A</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital dry cabinet</td>
			<td>Jwo Ruey Technical</td>
			<td>DRY-60</td>
			<td></td>
		</tr>
		<tr>
			<td>Dual-channel system sourcemeter</td>
			<td>Keithley</td>
			<td>2636B</td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation of large-area vertical 2d crystal hetero-structures through the sulfurization of transition metal films for device fabrication

硫化モリブデン (Mo)、タングステン (W)、大面積など遷移金属膜を通して実証を行い, 遷移金属ダイカルコゲナイド (Tmd) MoS2制服し、サファイア基板上 WS2を準備することができます。金属膜厚を制御することによりこの成長法を用いた Tmd の単一の層までの良好な層数制御が得られます。硫黄欠乏条件下で硫化 Mo フィルムから得られた結果に基づき、(a) 平面 MoS2成長および (b) 硫化処理中に観測された Mo 酸化物分離の 2 つのメカニズムがあります。背景硫黄が十分な平面の顎の成長、硫化処理後均一な MoS2膜になります優勢成長メカニズムです。背景硫黄が不足している場合、Mo 酸化物の偏析は硫化プロシージャの初期の段階で支配的な成長のメカニズムになります。この場合、覆われて少数層 MoS2 Mo 酸化物クラスターのサンプルが取得されます。後順次 Mo 蒸着/硫化および W 蒸着/硫化手順、垂直 WS2/MoS2ヘテロ構造は、この成長技術を使用して確立されます。WS2と MoS2にそれぞれ対応するラマンピークと個々 の 2 D マテリアルの総和によってヘテロ構造の同じ層数は垂直方向の 2次元結晶の成功確立を確認しています。ヘテロ構造。WS2パターン済みソース/ドレイン電極と SiO2/Si 基板上に/MoS2フィルムを転送した後下部ゲート トランジスタを作製しました。MoS2チャンネルのみでトランジスタと比べると、WS2/MoS2ヘテロ構造デバイスの高いドレイン電流が展示されて 2次元結晶ヘテロ構造、優れたデバイスの導入によりパフォーマンスが得られます。結果は、2次元結晶の実用的なアプリケーションのためのこの成長技術の可能性を明らかにしました。

ラマン スペクトルと個々 の MoS2と WS2事前入金の遷移金属の硫化を用いて作製したの断面の高分解能電顕像は、それぞれ図 1 ab17に表示されます。平面内に対応する MoS2と WS2の両方の 2 つの特徴的なラマンピークが観察される<img alt="Equation 1" src="/files/ftp_upload/56494/56494eq1.jpg">・面1 ...

Watch this Scientific Journal Video about Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication at JoVE.com

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

事前に堆積した遷移金属の硫化による大面積と垂直方向の 2次元結晶ヘテロ構造を加工できます。本報告ではフィルムの転送とデバイス作製手順も示します。

大面積垂直 2次元結晶ヘテロ構造デバイス作製のための遷移金属薄膜の硫化からの準備

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition ...

preparation-large-area-vertical-2d-crystal-hetero-structures-through

Research

JoVE Journal

Engineering

9.1K ビュー.  National Taiwan University. 事前に堆積した遷移金属の硫化による大面積と垂直方向の 2次元結晶ヘテロ構造を加工できます。本報告ではフィルムの転送とデバイス作製手順も示します。

ビデオ: Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

Fabrication And Characterization Of Photonic Crystal Slow Light Waveguides And Cavities

Slow light has been one of the hot topics in the photonics community in the past decade, generating great interest both from a fundamental point of view and for its considerable potential for practical applications. Slow light photonic crystal waveguides, in particular, have played a major part and have been successfully employed for delaying optical signals1-4 and the enhancement of both linear5-7 and nonlinear devices.8-11
Photonic crystal cavities achieve similar effects to that of slow light waveguides, but over a reduced band-width. These cavities offer high Q-factor/volume ratio, for the realization of optically12 and electrically13 pumped ultra-low threshold lasers and the enhancement of nonlinear effects.14-16 Furthermore, passive filters17 and modulators18-19 have been demonstrated, exhibiting ultra-narrow line-width, high free-spectral range and record values of low energy consumption.
To attain these exciting results, a robust repeatable fabrication protocol must be developed. In this paper we take an in-depth look at our fabrication protocol which employs electron-beam lithography for the definition of photonic crystal patterns and uses wet and dry etching techniques. Our optimised fabrication recipe results in photonic crystals that do not suffer from vertical asymmetry and exhibit very good edge-wall roughness. We discuss the results of varying the etching parameters and the detrimental effects that they can have on a device, leading to a diagnostic route that can be taken to identify and eliminate similar issues.
The key to evaluating slow light waveguides is the passive characterization of transmission and group index spectra. Various methods have been reported, most notably resolving the Fabry-Perot fringes of the transmission spectrum20-21 and interferometric techniques.22-25 Here, we describe a direct, broadband measurement technique combining spectral interferometry with Fourier transform analysis.26 Our method stands out for its simplicity and power, as we can characterise a bare photonic crystal with access waveguides, without need for on-chip interference components, and the setup only consists of a Mach-Zehnder interferometer, with no need for moving parts and delay scans.
When characterising photonic crystal cavities, techniques involving internal sources21 or external waveguides directly coupled to the cavity27 impact on the performance of the cavity itself, thereby distorting the measurement. Here, we describe a novel and non-intrusive technique that makes use of a cross-polarised probe beam and is known as resonant scattering (RS), where the probe is coupled out-of plane into the cavity through an objective. The technique was first demonstrated by McCutcheon et al.28 and further developed by Galli et al.29

Use of photonic crystal slow light waveguides and cavities has been widely adopted by the photonics community in many differing applications. Therefore fabrication and characterization of these devices are of great interest. This paper outlines our fabrication technique and two optical characterization methods, namely: interferometric (waveguides) and resonant scattering (cavities).

フォトニック結晶スローライト導波路とキャビティの作製と評価

Slow light has been one of the hot topics in the photonics community in the past decade, generating great interest both from a fundamental point of view ...

工学

Fabrication of VB2/Air Cells for Electrochemical Testing

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for synthesizing nanoscopic VB2 is presented as well as step-by-step procedure for applying a zirconium oxide coating to the VB2 particles for stabilization upon discharge. The process for disassembling existing zinc/air cells is shown, in addition construction of the new working electrode to replace the conventional zinc/air cell anode with a the nanoscopic VB2 anode. Finally, discharge of the completed VB2/air battery is reported. We show that using the zinc/air cell as a test bed is useful to provide a consistent configuration to study the performance of the high-energy high capacity nanoscopic VB2 anode.

Fabrication of VB2/Air Cells for Electrochemical Testing

A protocol is presented to study multi-electron metal/air battery systems by using previous technology developed for the zinc/air cell. Electrochemical testing is then performed on fabricated batteries to evaluate performance.

VBの作製<sub&gt; 2</sub電気テスト用&gt; /空気電池

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for ...

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-&#954; dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used.

A method for the growth of low temperature vertically-aligned carbon nanotubes, and the subsequent fabrication of vertical interconnect electrical test structures using semiconductor fabrication is presented.

半導体技術との互換性低温カーボンナノチューブ垂直相互接続の作製

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive ...

Preparation of Liquid-exfoliated Transition Metal Dichalcogenide Nanosheets with Controlled Size and Thickness: A State of the Art Protocol

We summarize recent advances in the production of liquid-exfoliated transition metal dichalcogenide (TMD) nanosheets with controlled size and thickness. Layered crystals of molybdenum disulphide (MoS2) and tungsten disulphide (WS2) are exfoliated in aqueous surfactant solution by sonication. This yields highly polydisperse mixtures containing nanosheets with broad size and thickness distributions. However, for most purposes, specific sizes (in terms of both lateral dimension and thickness) are required. For example, large and thin nanosheets are desired for (opto) electronic applications, while laterally small nanosheets are interesting for catalytic applications. Therefore, post-exfoliation size selection is an important step that we address here. We provide a detailed protocol on the efficient size selection in large quantities by liquid cascade centrifugation and the size and thickness quantification by statistical microscopic analysis (atomic force microscopy and transmission electron microscopy). The comparison of MoS2 and WS2 shows that both materials are size-selected in a similar way by the same procedure. Importantly, the dispersions of size-selected nanosheets show systematic changes in their optical extinction spectra with size due to edge and confinement effects. We show how these optical changes are related quantitatively to the nanosheets dimensions and describe how mean nanosheets length and layer number can be extracted reliably from the extinction spectra. The exfoliation and size selection protocol can be applied to a broad range of layered crystals as we have previously demonstrated for graphene, gallium sulphide (GaS) and black phosphorus.

A protocol for the liquid exfoliation of layered materials to nanosheets, their size selection and size measurement by microscopic and spectroscopic techniques is presented.

アートプロトコルの状態：制御された大きさと厚さを持つ液体-剥離遷移金属ジカルコゲニドナノシートの作製

We summarize recent advances in the production of liquid-exfoliated transition metal dichalcogenide (TMD) nanosheets with controlled size and thickness. ...

Fabrication of 1-D Photonic Crystal Cavity on a Nanofiber Using Femtosecond Laser-induced Ablation

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using femtosecond laser-induced ablation. We show that thousands of periodic nano-craters are fabricated on an optical nanofiber by irradiating with just a single femtosecond laser pulse. For a typical sample, periodic nano-craters with a period of 350 nm and with diameter gradually varying from 50 - 250 nm over a length of 1 mm are fabricated on a nanofiber with diameter around 450 - 550 nm. A key aspect of such a nanofabrication is that the nanofiber itself acts as a cylindrical lens and focuses the femtosecond laser beam on its shadow surface. Moreover, the single-shot fabrication makes it immune to mechanical instabilities and other fabrication imperfections. Such periodic nano-craters on nanofiber, act as a 1-D PhC and enable strong and broadband reflection while maintaining the high transmission out of the stopband. We also present a method to control the profile of the nano-crater array to fabricate apodized and defect-induced PhC cavities on the nanofiber. The strong confinement of the field, both transverse and longitudinal, in the nanofiber-based PhC cavities and the efficient integration to the fiber networks, may open new possibilities for nanophotonic applications and quantum information science.

We present a protocol for fabricating 1-D photonic crystal cavities on subwavelength diameter silica fibers (optical nanofibers) using femtosecond laser-induced ablation.

フェムト秒レーザー誘起アブレーションを用いたナノファイバー上の1次元フォトニック結晶共振器の作製

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using ...

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve desired molecular orientation states in LC displays, the "static" surface property of LCs, so-called surface anchoring, has been intensively studied. As a rule of thumb, once the initial orientation of LCs is "locked" by specific surface treatments, such as rubbing or treatment with a specific alignment layer, it hardly changes with temperature. Here, we present a system exhibiting an orientational transition upon temperature variation, which conflicts with the consensus. Right on the transition, the bulk LC molecules experience the orientational rotation, with 90&#176; between the planar (P) orientation at high temperatures and the vertical (V) orientation at low temperatures in the first-order transitional manner. We have tracked thermodynamic surface anchoring behavior by means of polarizing optical microscopy (POM), dielectric spectroscopy (DS), high-resolution differential scanning calorimetry (HR-DSC), and grazing incidence X-ray diffraction (GI-XRD) and reached a plausible physical explanation: that the transition is triggered by a growth of surface wetting sheets, which impose the V orientation locally against the P orientation in the bulk. This landscape would provide a general link explaining how the equilibrium bulk orientation is affected by surface-localized orientation in many LC systems. In our characterization, POM and DS are advantageous by offering information on the spatial distribution of the orientation of LC molecules. HR-DSC gives information about the precise thermodynamic information on transitions, which cannot be addressed by conventional DSC instruments due to limited resolution. GI-XRD provides information on surface-specific molecular orientation and short-range orderings. The goal of this paper is to present a protocol for preparing a sample that exhibits the transition and to demonstrate how the thermodynamic structural variation, both in the bulk and on surfaces, can be analyzed through the abovementioned methods.

Here, we present a protocol to trigger an orientational transition of a liquid crystal in response to temperature. Methodologies are described for preparing a sample in order to observe the transition and the detailed transitional evolution.

界面湿潤シートの熱力学的成長によって引き起こされる液晶の配向転移

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve ...

Scalable Solution-processed Fabrication Strategy for High-performance, Flexible, Transparent Electrodes with Embedded Metal Mesh

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a polymer film. This paper also presents a low-cost, vacuum-free fabrication method for this novel TE; the approach combines lithography, electroplating, and imprint transfer (LEIT) processing. The embedded nature of the EMTEs offers many advantages, such as high surface smoothness, which is essential for organic electronic device production; superior mechanical stability during bending; favorable resistance to chemicals and moisture; and strong adhesion with plastic film. LEIT fabrication features an electroplating process for vacuum-free metal deposition and is favorable for industrial mass production. Furthermore, LEIT allows for the fabrication of metal mesh with a high aspect ratio (i.e., thickness to linewidth), significantly enhancing its electrical conductance without adversely losing optical transmittance. We demonstrate several prototypes of flexible EMTEs, with sheet resistances lower than 1 &#937;/sq and transmittances greater than 90%, resulting in very high figures of merit (FoM) &#8211; up to 1.5 x 104 &#8211; which are amongst the best values in the published literature.

This protocol describes a solution-based fabrication strategy for high-performance, flexible, transparent electrodes with fully-embedded, thick metal mesh. Flexible transparent electrodes fabricated by this process demonstrate among the highest reported performances, including ultra-low sheet resistance, high optical transmittance, mechanical stability under bending, strong substrate adhesion, surface smoothness, and environmental stability.

埋め込み金属メッシュを用いた高性能で柔軟で透明な電極のための拡張可能なソリューション処理製作戦略

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a ...

Preparation of Liquid Crystal Networks for Macroscopic Oscillatory Motion Induced by Light

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous light irradiation. The photo-excitation of dopants that can quickly dissipate light into heat, coupled with anisotropic thermal expansion and self-shadowing of the film, gives rise to the self-sustained deformation. The oscillations observed are influenced by the dimensions and the modulus of the film, and by the directionality and intensity of the light. The system developed offers applications in energy conversion and harvesting for soft-robotics and automated systems.
The general method described here consists of creating free-standing liquid crystalline films and characterizing the mechanical and thermal effects observed. The molecular alignment is achieved using alignment layers (rubbed polyimide), commonly used in the display manufacturing industry. To obtain actuators with large deformation, the mesogens are aligned and polymerized in a splay/bend configuration, i.e., with the director of the liquid crystals (LCs) going gradually from planar to homeotropic through the film thickness. Upon irradiation, the mechanical and thermal oscillations obtained are monitored with a high-speed camera. The results are further quantified by image analysis using an image processing program.

The goal of the protocol is to create liquid crystalline polymer films that can mechanically oscillate under continuous light irradiation. We describe in great detail the conception of free-standing films, from the liquid crystal alignment method to the photo-actuation. The experimental protocol applied to prepare this material is broadly applicable.

巨視的揺動運動の光によって誘起される液晶ネットワークの準備

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous ...

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.&#160; Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

We present a detailed method for fabricating ultra-thin color films with improved characteristics for optical coatings. The oblique angle deposition technique using an electron beam evaporator allows improved color tunability and purity. Fabricated films of Ge and Au on Si substrates were analyzed by reflectance measurements and color information conversion.

斜め蒸着を使用してメディアを高吸収極薄カラー フィルムの作製

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present ...

Atmospheric Pressure Fabrication of Large-Sized Single-Layer Rectangular SnSe Flakes

Tin selenide (SnSe) belongs to the family of layered metal chalcogenide materials with a buckled structure like phosphorene, and has shown potential for applications in two-dimensional nanoelectronics devices. Although many methods to synthesize SnSe nanocrystals have been developed, a simple way to fabricate large-sized single-layer SnSe flakes remains a great challenge. Herein, we show the experimental method to directly grow large-sized single-layer rectangular SnSe flakes on commonly used SiO2/Si insulating substrates using a straightforward two-step fabrication method in an atmospheric pressure quartz tube furnace system. The single-layer rectangular SnSe flakes with an average thickness of ~6.8 &#197; and lateral dimensions of about 30 &#181;m &#215; 50 &#181;m were fabricated by a combination of vapor transport deposition technique and nitrogen etching route. We characterized the morphology, microstructure, and electrical properties of the rectangular SnSe flakes and obtained excellent crystallinity and good electronic properties. This article about the two-step fabrication method can help researchers grow other similar two-dimensional, large-sized, single-layer materials using an atmospheric pressure system.

A protocol is presented demonstrating a two-step fabrication technique to grow large-sized single-layer rectangular shaped SnSe flakes on low-cost SiO2/Si dielectrics wafers in an atmospheric pressure quartz tube furnace system.

大型単層長方形 SnSe フレークの大気圧作製

Tin selenide (SnSe) belongs to the family of layered metal chalcogenide materials with a buckled structure like phosphorene, and has shown potential for ...