この研究は、米国エネルギー省によって資金を供給エネルギーナノサイエンス、エネルギーフロンティア研究センターセンター、受賞番号DE-SC0001013下科学局の一部としてサポートされていました。また、TiO 2の膜スパッタリングおよび屈折率測定への彼らの助けのために博士マックス·チャンとHP研究所の博士建華ヤンに感謝したいと思います。

1.ナノインプリントモールド用のブランクポリジメチルシロキサン（PDMS）基板を準備します<ol><li>シリコンウェーハ処理プロセス<ol><li>アセトン、メタノール、イソプロパノールですすぐことによって、4インチのシリコンウエハを清掃してください。 </li><li>それは窒素ガンを用いてブロー乾燥。 </li><li> 15分間の内部に浸漬することにより：（30％過酸化水素水と硫酸の1混合物3）ピラニア溶液を使用して清掃してください。 </li><li> DI水でそれを洗浄します。窒素ガンを用いたドライ吹きます。 </li><li>ガラスデシケーター中でウエハを配置します。デシケーター中に薬剤（トリクロロシラン）を放出するドロップ（20滴= 1ミリリットル）を追加します。 </li><li>ゲージは-762トルを読み取るまでデシケーターをポンプダウンし、5時間を待ちます。 </li><li>離型剤で処理されたウェハアウトを取ります。 </li></ol></li><li> PDMSフィルムの作製（ナノインプリントにおけるモールドとして使用されます） <ol><li>シリコーンエラストマーベース10gと硬化剤1gを秤量します。 </li><li>同一のガラスビーカーにそれらを追加します。 </li><li> STI5分間、ガラス棒でrと混ぜます。 </li><li>ゲージはすべて捕捉された気泡を送り出すために-762トルを読み取るまで、真空デシケーターに混合物を入れてください。 </li><li>処理した4インチのシリコンウェーハ上に均等に広げます。 </li><li> PDMS膜を硬化させるために80℃で7時間、真空オーブン中で上にPDMSを有するウェーハを焼きます。 </li></ol></li></ol> 2.ナノインプリントモールド（マスターモールドから複製）を準備<ol><li> 1,500rpmで30秒間清浄なブランクシリコンウェハ上に硬化性レジストをUVの12滴（20滴= 1ml）中（15.2％）をスピン。 </li><li>慎重に処理されたシリコンウェハオフPDMS膜の一部を剥離。 </li><li>硬化性レジストUV上にPDMSフィルムを入れて、それが紫外線を5分間耐えることをはがし吸収しましょう​​。 </li><li> 2回同じPDMS膜上に2.1〜2.3を繰り返します。それぞれ3分、1分間耐えるUVを吸収します。 </li><li> （3回の紫外線吸収に抵抗した後）は、シリコンマスターモールドにPDMSフィルムを配置します。 </li><li>窒素環境と室内に入れて。 </li><li> 5分間のサンプルを硬化させるためにUVランプをオンにします。 </li><li> PDMSフィルムをはがし。 UV硬化PDMS上のレジストは、マスター型のネガパターンを維持します。 </li><li> PDMSモールドを治療するためのRF O 2プラズマを使用してください。 （RFパワー：30 W、圧力：260トール、時間：1分） </li><li> 2時間離型剤の一滴（20滴= 1ml）で真空チャンバ内のPDMSモールドを配置します。 </li></ol> 3.ナノインプリントパターン転写<ol><li> 3,500 rpmで50秒間、インプリントされる基板上にPMMA（996k、3.1％）、8滴（20滴= 1 ml）をスピン。 </li><li> 120℃で5分間、ホットプレート上で焼きます。 </li><li>試料が冷却するのを待ちます。 </li><li> UV硬化性の8滴（20滴= 1 ml）を同一基板上にスピン（3.9％）をレジスト</li><li>サンプル（UVの両方でレジストPMMA）上にPDMSモールド（ステップ2で調製）を配置します。 </li><li>窒素環境と室内に入れて。</li><li> 5分間硬化させるためにUVランプをオンにします。 </li><li>ピールサンプルオフPDMSモールドとPDMSモールド上のパターンを試料に転送されます。 </li></ol> 4.クロムリフトオフプロセス<ol><li> UVの残留層を反応性イオンエッチングレジストおよびPMMA 注：ICPマシンのSOPはhttps://www.nanocenter.umd.edu/equipment/fablab/sops/etch-07/Oxford%20Chlorine%20Etcher%20SOP.pdfで見つけることができます<ol><li> RIE、ICPマシンにログインします。 </li><li>空白の4インチのシリコンウェーハをロードします。 10分間きれいなレシピを実行します。 </li><li>ブランクシリコンウエハを取り出してください。 </li><li>別の清浄なシリコンウェハ上にサンプルをマウントし、マシンにロードします。 </li><li> 2分間のエッチングレシピをレジストUVを実行します（レシピは、表1に見ることができます）。 </li><li>サンプルを取り出します。空白の4インチのシリコンウェーハをロードします。再実行しクリーンなレシピを10分間（ 表1を参照のこと）。 </li><li>清浄なシリコンウェハ上にサンプルをマウントしますマシンにロードします。 </li><li> 2分間（ 表1に見ることができる）、PMMAのエッチングレシピを実行します。 注：ここでの残留がエッチングされたレジストを基板が露出しています。 </li></ol></li><li> Crの電子ビーム蒸着<ol><li>電子ビーム蒸発器にログインします。 </li><li>チャンバー内にCr金属源とサンプルをロードします。 </li><li>厚さ（20 nm）を蒸着速度（0.03 nmの/秒）を設定します。 </li><li>必要な真空（10 -7トル）が到達するまで、チャンバポンプ。 </li><li>堆積プロセスを開始します。 </li><li>成膜終了後の試料を取り出します。 </li></ol></li><li> CRリフトオフ手順<ol><li> 5分間の超音波撹拌しながらアセトン中に試料を浸し。 </li><li>アセトン、メタノール、イソプロパノールでリンスすることにより、サンプルを清掃してください。 注：Crはレジストのリフトオフされ、基板エッチングのためのCrマスクを形成する上で蒸発させました。 </li></ol></li></ol> 5.のTiO 2発osition <ol><li>ロードサンプル。 </li><li>直流マグネトロンスパッタリングマシンのパラメータを設定します<ol><li> 1.5ミリトールのチャンバ圧力、100sccmのアルゴンの流れと130 Wのスパッタ電力を使用して</li><li> 27℃の温度および20回転数のステージ回転速度を使用してください。 </li></ol></li><li>スパッタプロセスを開始し、所望の厚さで停止します。 </li><li>サンプルを取り出し、3時間300℃の酸素雰囲気中のTiO 2膜をアニール。 </li></ol> 6.ハイコントラストグレーティングエッチング<ol><li>誘導結合プラズマ（ICP）反応性イオンエッチング（RIE）マシンにログインします。 </li><li> TiO 2のエッチング<ol><li>ブランク4インチのシリコンウェーハをロードします。 </li><li> 10分間（ 表1に見ることができる）クリーンレシピを起動し、実行します。 </li><li>ブランクウエハをロードアンロードし、Crマスクでサンプルをロードします。 </li><li>エッチング時間を設定します。 TiO 2のエッチングレシピを開始します。エッチングプロセスが自動matically停止。 </li><li>サンプルをアンロードします。 </li></ol></li><li> SiO 2のエッチング<ol><li> SiO 2のエッチングレシピを使用する以外は手順を繰り返し5.2。 </li></ol></li></ol> 7.反射率測定<ol><li>ログインして、測定システムの電源をオンにします。 </li><li>試料ホルダーに、反射率標準ミラーを配置し、光路の位置を合わせます。 </li><li> 100％の反射率のためのシステムのキャリブレーション。 </li><li>反射率標準ミラーを外し、HCGを配置します。 </li><li> HCGの反射率を測定します。 </li><li>データを保存し、測定システムからログアウトします。 </li></ol>

<ol>
	<li>Horne, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Solid+500+Sun+Compound+Concentrator+PV+Design.">A Solid 500 Sun Compound Concentrator PV Design.</a> Photovoltaic Energy Conversion, Conference Record of the 2006 IEEE 4th World Conference on. , 694-697 (2006).</li><li>Guter, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current-matched+triple-junction+solar+cell+reaching+41.1%+conversion+efficiency+under+concentrated+sunlight.">Current-matched triple-junction solar cell reaching 41.1% conversion efficiency under concentrated sunlight.</a> Applied Physics Letters. 94, 223504 (2009).</li><li>Shockley, W., Queisser, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detailed+Balance+Limit+of+Efficiency+of+p-n+Junction+Solar+Cells.">Detailed Balance Limit of Efficiency of p-n Junction Solar Cells.</a> Journal of Applied Physics. 32, 510-519 (1961).</li><li>Green, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Potential+for+low+dimensional+structures+in+photovoltaics.">Potential for low dimensional structures in photovoltaics.</a> Materials Science and Engineering: B. 74, 118-124 (2000).</li><li>Karagodsky, V., Chang-Hasnain, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physics+of+near-wavelength+high+contrast+gratings.">Physics of near-wavelength high contrast gratings.</a> Opt. Express. 20, 10888-10895 (2012).</li><li>Chou, S. Y., Krauss, P. R., Renstrom, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoimprint+lithography.">Nanoimprint lithography.</a> Journal of Vacuum Science &amp; Technology B: Microelectronics and Nanometer Structures. 14, 4129-4133 (1996).</li><li>Namiki, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+FDTD+algorithm+based+on+alternating-direction+implicit+method.+Microwave+Theory+and+Techniques.">A new FDTD algorithm based on alternating-direction implicit method. Microwave Theory and Techniques.</a> IEEE Transactions on. 47, 2003-2007 (1999).</li><li>Moharam, M. G., Gaylord, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rigorous+coupled-wave+analysis+of+planar-grating+diffraction.">Rigorous coupled-wave analysis of planar-grating diffraction.</a> J. Opt. Soc. Am. 71, 811-818 (1981).</li><li>Yao, Y., Liu, H., Wu, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectrum+splitting+using+multi-layer+dielectric+meta-surfaces+for+efficient+solar+energy+harvesting.">Spectrum splitting using multi-layer dielectric meta-surfaces for efficient solar energy harvesting.</a> Appl. Phys. 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H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sub-50+nm+period+patterns+with+EUV+interference+lithography.">Sub-50 nm period patterns with EUV interference lithography.</a> Microelectronic Engineering. 67, 56-62 (2003).</li><li>Li, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hybrid+nanoimprint&#8722;+soft+lithography+with+sub-15+nm+resolution.">Hybrid nanoimprint&#8722; soft lithography with sub-15 nm resolution.</a> Nano letters. 9, 2306-2310 (2009).</li><li>Yu, Z., Chen, L., Wu, W., Ge, H., Chou, S. 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The authors have nothing to disclose.

まず、TiO 2の膜の品質は、HCGのパフォーマンスのために非常に重要です。 TiO 2のフィルムが少ない損失と表面粗さを有する場合、反射率ピークが高くなります。光学モードの閉じ込めがHCGで平坦で広い反射バンドを生じさせることができ指数の高いコントラストによって強化されるため、より高い屈折率を有するTiO 2の膜も良好です。 第二に、製?...

現代社会は、再生可能なエネルギー源へのエネルギー消費量のかなりの部分を移動させずに生存しないであろう。これを実現するために、我々は近い将来、石油系エネルギー源よりも低コストで再生可能エネルギーを収穫する方法を見つける必要があります。太陽エネルギーは地球上で最も豊富な再生可能エネルギーです。進歩の多くは太陽エネルギーハーベスティングで行われていることにもかかわらず、石油系エネルギー源と競合することは非常に困難です。太陽電池の効率を改善することは、太陽エネルギーハーベスティングのシステムコストを低減するための最も効率的な方法の一つです。 それに高価なタンデム多接合太陽電池セル2を利用することが経済的に実行可能であるように光学レンズ及びディッシュ反射器は、通常、小面積の太陽電池に太陽光発電入射高濃度を達成するために最も集中太陽光発電（CPV）システム1で使用されていますCPVシステム、及び妥当性を維持します同時にコスト。それらは通常、より広い太陽スペクトル応答よりも高い全体的な変換効率を有するものの、通常、太陽電池の大面積の設置を必要とするほとんどの非濃縮太陽光発電システムのための、高コストのタンデム太陽電池は、組み込むことができません単接合太陽電池3。 近年、並列スペクトル分割光学系（ すなわち、分散素子）を利用して、並列スペクトル分割太陽光発電技術4により、類似またはより良好なスペクトル範囲と変換効率が高価タンデム型太陽電池を使用することなく達成できることになりました。太陽スペクトルの異なる帯域に分割することができ、それぞれのバンドが吸収され、特殊な単接合太陽電池によって電気に変換することができます。このように、CPVシステムで高価なタンデム型太陽電池は、単接合太陽電池の並列分布に置き換えることができますパフォーマンスに妥協することなく複数。 この報告書に設計された分散素子は、改善された太陽光電力変換効率およびコスト削減のための並列スペクトル分割を実現するために（ディッシュ反射に基づいて）反射CPVシステムに適用することができます。多層高コントラスト回折格子（HCG）5は、光バンドリフレクタとして機能するようにHCGの各層を設計することにより、分散素子として使用されます。分散素子の構造やパラメータが数値的に最適化されています。また、（TiO 2の）誘電スパッタリング、ナノインプリントリソグラフィ6と反応性イオンエッチングを使用して、分散素子のための高コントラスト回折格子の製造を検討し、実証されています。

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>184 SILICONE ELASTOMER KIT</td>
			<td>SYLGARD</td>
			<td></td>
			<td>Polydimethylsiloxane (PDMS)</td>
		</tr>
		<tr>
			<td>4-inch silicon wafer</td>
			<td>Universitywafer</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4-inch fused silica wafer</td>
			<td>Universitywafer</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Poly(methyl methacrylate)</td>
			<td>SIGMA-ALDRICH</td>
			<td align="right">182265</td>
			<td></td>
		</tr>
		<tr>
			<td>UV-curable resist</td>
			<td></td>
			<td></td>
			<td>Nor available on market</td>
		</tr>
		<tr>
			<td>PlasmaLab System 100</td>
			<td>Oxford Instruments</td>
			<td></td>
			<td>ICP IRE machine</td>
		</tr>
		<tr>
			<td>UV curing system for nanoimprint fabrication</td>
			<td></td>
			<td></td>
			<td>Not available on market</td>
		</tr>
		<tr>
			<td>Ocean Optics HR-4000&#160;</td>
			<td>Ocean Optics</td>
			<td>HR-4000</td>
			<td>Spectrometer with normal detector</td>
		</tr>
		<tr>
			<td>Lambda 950 UV / VIS</td>
			<td>PerkinElmer</td>
			<td></td>
			<td>spectrometer with hemisphere intergration detector</td>
		</tr>
		<tr>
			<td>JSM-7001F-LV</td>
			<td>JEOL</td>
			<td></td>
			<td>Field emission SEM</td>
		</tr>
		<tr>
			<td>DC magnetron sputtering machine</td>
			<td></td>
			<td></td>
			<td>Equipment is in HP labs, who helped us to sputter the TiO2</td>
		</tr>
		<tr>
			<td>Metal e-beam evaporator</td>
			<td>Temescal</td>
			<td>BJD-1800</td>
			<td></td>
		</tr>
	</tbody>
</table>

fabrication of high contrast gratings for the spectrum splitting dispersive element in a concentrated photovoltaic system

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve the solar conversion efficiency of a concentrated photovoltaic system. The proposed system will also lower the solar cell cost in the concentrated photovoltaic system by replacing the expensive tandem solar cells with the cost-effective single junction solar cells. The structures and the parameters of high contrast gratings for the dispersive elements were numerically optimized. The large-area fabrication of high contrast gratings was experimentally demonstrated using nanoimprint lithography and dry etching. The quality of grating material and the performance of the fabricated device were both experimentally characterized. By analyzing the measurement results, the possible side effects from the fabrication processes are discussed and several methods that have the potential to improve the fabrication processes are proposed, which can help to increase the optical efficiency of the fabricated devices.

図1は、濃縮された太陽光発電システムにおける分散素子（回折格子多層高コントラスト（HCG））の実装を示しています。太陽の光は、第1の一次ミラーで反射され、ビームは反射し、異なる波長の異なる帯域に分割され、反射分散素子に入射されます。各バンドは電気への最高の吸収および変換のための太陽電池アレイ上の特定の場所に衝突します。このシステムの鍵は、HCGの?...

Watch this Scientific Journal Video about Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System at JoVE.com

Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System

The fabrication of high contrast gratings as the parallel spectrum splitting dispersive element in a concentrated photovoltaic system is demonstrated. Fabrication processes including nanoimprint lithography, TiO2 sputtering and reactive ion etching are described. Reflectance measurement results are used to characterize the optical performance.

集中太陽光発電システムにおけるスペクトル分割分散素子の高コントラスト回折格子の作製

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve ...

fabrication-high-contrast-gratings-for-spectrum-splitting-dispersive

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10.6K ビュー.  University of Sothern California. The fabrication of high contrast gratings as the parallel spectrum splitting dispersive element in a concentrated photovoltaic system is demonstrated. Fabrication processes including nanoimprint lithography, TiO2 sputtering and reactive ion etching are described. Reflectance measurement results are used to characterize the optical performance. 

ビデオ: Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System

Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging (ECCI) in a scanning electron microscope (SEM). ECCI allows for imaging of defects and crystallographic features under specific diffraction conditions, similar to that possible via plan-view transmission electron microscopy (PV-TEM). A particular advantage of the ECCI technique is that it requires little to no sample preparation, and indeed can use large area, as-produced samples, making it a considerably higher throughput characterization method than TEM. Similar to TEM, different diffraction conditions can be obtained with ECCI by tilting and rotating the sample in the SEM. This capability enables the selective imaging of specific defects, such as misfit dislocations at the GaP/Si interface, with high contrast levels, which are determined by the standard invisibility criteria. An example application of this technique is described wherein ECCI imaging is used to determine the critical thickness for dislocation nucleation for GaP-on-Si by imaging a range of samples with various GaP epilayer thicknesses. Examples of ECCI micrographs of additional defect types, including threading dislocations and a stacking fault, are provided as demonstration of its broad, TEM-like applicability. Ultimately, the combination of TEM-like capabilities &#8211; high spatial resolution and richness of microstructural data &#8211; with the convenience and speed of SEM, position ECCI as a powerful tool for the rapid characterization of crystalline materials.

The use of electron channeling contrast imaging in a scanning electron microscope to characterize defects in III-V/Si heteroexpitaxial thin films is described. This method yields similar results to plan-view transmission electron microscopy, but in significantly less time due to lack of required sample preparation.

迅速なIII-Vヘテロ特徴付けのための電子チャネリングコントラストイメージング

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging ...

工学

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.
Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of &gt; 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.
Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

個々のナノ粒子の3次元元素マッピングのためのエネルギー分散型X線トモグラフィー

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial ...

Writing Bragg Gratings in Multicore Fibers

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers.

We describe a technique for inscribing identical fiber Bragg gratings into each core of a multicore fiber. This is achieved by introducing an additional surface into the optical path to mitigate lensing by the curved surface of the fiber cladding.

マルチコアファイバーブラッググレーティングを書きます

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong ...

Fabrication of Fully Solution Processed Inorganic Nanocrystal Photovoltaic Devices

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal inks. For the photoactive absorber layer, colloidal CdTe and CdSe nanocrystals (3-5 nm) are synthesized using an inert hot injection technique and cleaned with precipitations to remove excess starting reagents. Similarly, gold nanocrystals (3-5 nm) are synthesized under ambient conditions and dissolved in organic solvents. In addition, precursor solutions for transparent conductive indium tin oxide (ITO) films are prepared from solutions of indium and tin salts paired with a reactive oxidizer. Layer-by-layer, these solutions are deposited onto a glass substrate following annealing (200-400 &#176;C) to build the nanocrystal solar cell (glass/ITO/CdSe/CdTe/Au). Pre-annealing ligand exchange is required for CdSe and CdTe nanocrystals where films are dipped in NH4Cl:methanol to replace long-chain native ligands with small inorganic Cl- anions. NH4Cl(s) was found to act as a catalyst for the sintering reaction (as a non-toxic alternative to the conventional CdCl2(s) treatment) leading to grain growth (136&#177;39 nm) during heating. The thickness and roughness of the prepared films are characterized with SEM and optical profilometry. FTIR is used to determine the degree of ligand exchange prior to sintering, and XRD is used to verify the crystallinity and phase of each material. UV/Vis spectra show high visible light transmission through the ITO layer and a red shift in the absorbance of the cadmium chalcogenide nanocrystals after thermal annealing. Current-voltage curves of completed devices are measured under simulated one sun illumination. Small differences in deposition techniques and reagents employed during ligand exchange have been shown to have a profound influence on the device properties. Here, we examine the effects of chemical (sintering and ligand exchange agents) and physical treatments (solution concentration, spray-pressure, annealing time and annealing temperature) on photovoltaic device performance.

This protocol describes the synthesis and solution deposition of inorganic nanocrystals layer by layer to produce thin film electronics on non-conductive surfaces. Solvent-stabilized inks can produce complete photovoltaic devices on glass substrates via spin and spray coating following post-deposition ligand exchange and sintering.

完全に解決策が処理無機ナノ結晶太陽電池素子の作製

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal ...

Recombination Dynamics in Thin-film Photovoltaic Materials via Time-resolved Microwave Conductivity

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials such as organo-lead halide perovskites is presented. The perovskite film thickness and absorption coefficient are initially characterized by profilometry and UV-VIS absorption spectroscopy. Calibration of both laser power and cavity sensitivity is described in detail. A protocol for performing Flash-photolysis Time Resolved Microwave Conductivity (TRMC) experiments, a non-contact method of determining the conductivity of a material, is presented. A process for identifying the real and imaginary components of the complex conductivity by performing TRMC as a function of microwave frequency is given. Charge carrier dynamics are determined under different excitation regimes (including both power and wavelength). Techniques for distinguishing between direct and trap-mediated decay processes are presented and discussed. Results are modelled and interpreted with reference to a general kinetic model of photoinduced charge carriers in a semiconductor. The techniques described are applicable to a wide range of optoelectronic materials, including organic and inorganic photovoltaic materials, nanoparticles, and conducting/semiconducting thin films.

A Time Resolved Microwave Conductivity technique for investigating direct and trap-mediated recombination dynamics and determining carrier mobilities of thin film semiconductors is presented here.

時間分解マイクロ波伝導を介して、薄膜太陽電池材料での再結合ダイナミクス

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials ...

Challenges in Rheological Characterization of Highly Concentrated Suspensions &#8212; A Case Study for Screen-printing Silver Pastes

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the manifold requirements during processing and application of such complex fluids. In this investigation, measuring protocols for a conclusive assessment of different process relevant rheological parameters have been evaluated. This includes the determination of yield stress, viscosity, wall slip velocity, structural recovery after large deformation and elongation at break as well as tensile force during filament stretching.
The importance of concomitant video recordings during parallel-plate rotational rheometry for a significant determination of rheological quantities is demonstrated. The deformation profile and flow field at the sample edge can be determined using appropriate markers. Thus, measurement parameter settings and plate roughness values can be identified for which yield stress and viscosity measurements are possible. Slip velocity can be measured directly and measuring conditions at which plug flow, shear banding or sample spillover occur can be identified clearly. 
Video recordings further confirm that the change in shear moduli observed during three stage oscillatory shear tests with small deformation amplitude in stage I and III but large oscillation amplitude in stage II can be directly attributed to structural break down and recovery. For the pastes investigated here, the degree of irreversible, shear-induced structural change increases with increasing deformation amplitude in stage II until a saturation is reached at deformations corresponding to the crossover of G' and G'', but the irreversible damage is independent of the duration of large amplitude shear. 
A capillary breakup elongational rheometer and a tensile tester have been used to characterize deformation and breakup behavior of highly filled pastes in uniaxial elongation. Significant differences were observed in all experiments described above for two commercial screen-printing silver pastes used for front side metallization of Si-solar cells.

Challenges in Rheological Characterization of Highly Concentrated Suspensions &amp;#8212; A Case Study for Screen-printing Silver Pastes

A protocol for a robust and application relevant rheological characterization of highly concentrated suspensions is presented. Silver pastes used for screen-printing application in solar cell production are employed as model systems.

高度に濃縮された懸濁液のレオロジー特性評価における課題 - スクリーン印刷シルバーペーストのためのケーススタディ

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the ...

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia (YSZ) Scaffolds by In Situ Carbon Templating Xerogels

We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) scaffolds with tunable specific surface areas up to 80 m2&#183;g-1. An aqueous solution of a zirconium salt, yttrium salt, and glucose is mixed with propylene oxide (PO) to form a gel. The gel is dried under ambient conditions to form a xerogel. The xerogel is pressed into pellets and then sintered in an argon atmosphere. During sintering, a YSZ ceramic phase forms and the organic components decompose, leaving behind amorphous carbon. The carbon formed in situ serves as a hard template, preserving a high surface area YSZ nanomorphology at sintering temperature. The carbon is subsequently removed by oxidation in air at low temperature, resulting in a porous, nanostructured YSZ scaffold. The concentration of the carbon template and the final scaffold surface area can be systematically tuned by varying the glucose concentration in the gel synthesis. The carbon template concentration was quantified using thermogravimetric analysis (TGA), the surface area and pore size distribution was determined by physical adsorption measurements, and the morphology was characterized using scanning electron microscopy (SEM). Phase purity and crystallite size was determined using X-ray diffraction (XRD). This fabrication approach provides a novel, flexible platform for realizing unprecedented scaffold surface areas and nanomorphologies for ceramic-based electrochemical energy conversion applications, e.g. solid oxide fuel cell (SOFC) electrodes.

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia YSZ Scaffolds by In Situ Carbon Templating Xerogels

A protocol for fabricating porous, nanostructured yttria-stabilized-zirconia (YSZ) scaffolds at temperatures between 1,000 &#176;C and 1,400 &#176;C is presented.

によってナノ構造イットリア安定化ジルコニア（YSZ）足場の高温製作<em&gt;その場での</em&gt;カーボンテンプレート化キセロゲル

We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) ...

Detecting the Water-soluble Chloride Distribution of Cement Paste in a High-precision Way

To improve the accuracy of the chloride distribution along the depth of cement paste under cyclic wet-dry conditions, a new method is proposed to obtain a high-precision chloride profile. Firstly, paste specimens are molded, cured, and exposed to cyclic wet-dry conditions. Then, powder samples at different specimen depths are grinded when the exposure age is reached. Finally, the water-soluble chloride content is detected using a silver nitrate titration method, and chloride profiles are plotted. The key to improving the accuracy of the chloride distribution along the depth is to exclude the error in the powderization, which is the most critical step for testing the distribution of chloride. Based on the above concept, the grinding method in this protocol can be used to grind powder samples automatically layer by layer from the surface inward, and it should be noted that a very thin grinding thickness (less than 0.5 mm) with a minimum error less than 0.04 mm can be obtained. The chloride profile obtained by this method better reflects the chloride distribution in specimens, which helps researchers to capture the distribution features that are often overlooked. Furthermore, this method can be applied to studies in the field of cement-based materials, which require high chloride distribution accuracy.

A protocol for obtaining a water-soluble chloride profile by using a high precision milling method is presented.

セメント ペーストの水溶性塩化物の分布を高精度に検出

To improve the accuracy of the chloride distribution along the depth of cement paste under cyclic wet-dry conditions, a new method is proposed to obtain a ...

Method for Recording Broadband High Resolution Emission Spectra of Laboratory Lightning Arcs

Lightning is one of the most common and destructive forces in nature and has long been studied using spectroscopic techniques, first with traditional camera film methods and then digital camera technology, from which several important characteristics have been derived. However, such work has always been limited due to the inherently random and non-repeatable nature of natural lightning events in the field. Recent developments in lightning test facilities now allow the reproducible generation of lightning arcs within controlled laboratory environments, providing a test bed for the development of new sensors and diagnostic techniques to understand lightning mechanisms better. One such technique is a spectroscopic system using digital camera technology capable of identifying the chemical elements with which the lightning arc interacts, with these data then being used to derive further characteristics. In this paper, the spectroscopic system is used to obtain the emission spectrum from a 100 kA peak, 100 &#181;s duration lightning arc generated across a pair of hemispherical tungsten electrodes separated by a small air gap. To maintain a spectral resolution of less than 1 nm, several individual spectra were recorded across discrete wavelength ranges, averaged, stitched, and corrected to produce a final composite spectrum in the 450 nm (blue light) to 890 nm (near infrared light) range. Characteristic peaks within the data were then compared to an established publicly available database to identify the chemical element interactions. This method is readily applicable to a variety of other light emitting events, such as fast electrical discharges, partial discharges, and sparking in electrical equipment, apparatus, and systems.

Emission spectroscopy techniques have traditionally been used to analyze inherently random lightning arcs occurring in nature. In this paper, a method developed to obtain the emission spectroscopy from reproducible lightning arcs generated within a laboratory environment is described.

実験室雷アークの広帯域高解像度発光スペクトルの記録方法

Lightning is one of the most common and destructive forces in nature and has long been studied using spectroscopic techniques, first with traditional ...

Flow-assisted Dielectrophoresis: A Low Cost Method for the Fabrication of High Performance Solution-processable Nanowire Devices

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of nanowires. DEP is used for nanowire analysis, characterization, and for solution-based fabrication of semiconducting devices. The method works by applying an alternating electric field between metallic electrodes. The nanowire formulation is then dropped onto the electrodes which are on an inclined surface to create a flow of the formulation using gravity. The nanowires then align along the gradient of the electric field and in the direction of the liquid flow. The frequency of the field can be adjusted to select nanowires with superior conductivity and lower trap density. 
In this work, flow-assisted DEP is used to create nanowire field effect transistors. Flow-assisted DEP has several advantages: it allows selection of nanowire electrical properties; control of nanowire length; placement of nanowires in specific areas; control of orientation of nanowires; and control of nanowire density in the device. 
The technique can be expanded to many other applications such as gas sensors and microwave switches. The technique is efficient, quick, reproducible, and it uses a minimal amount of dilute solution making it ideal for the testing of novel nanomaterials. Wafer scale assembly of nanowire devices can also be achieved using this technique, allowing large numbers of samples for testing and large-area electronic applications.

In this paper, flow assisted dielectrophoresis is demonstrated for the self-assembly of nanowire devices. The fabrication of a silicon nanowire field effect transistor is shown as an example.

誘電泳動の流れ支援: 高性能低温硬化型ナノワイヤ デバイス作製のための低コストの方法

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of ...