이 연구는 에너지 나노, 수상 번호 DE-SC0001013에서 에너지, 과학의 사무실의 미 교육부에 의해 투자 에너지 프론티어 연구 센터의 센터의 한 부분으로 지원되었다. 우리는 또한 이산화 티탄 박막 스퍼터링 및 굴절률 측정에 그들의 도움 박사 최대 장과 HP 연구소의 박사 지안 후아 양 감사드립니다.

나노 임프린트 몰드 1. 빈 폴리 디메틸 실록산을 준비 (PDMS) 기판 <ol><li> 실리콘 웨이퍼 처리 공정 <ol><li> 아세톤, 메탄올 및 이소프로판올로 세척하여 4 인치 실리콘 웨이퍼를 청소한다. </li><li> 이 질소 총을 이용한 드라이 불어. </li><li> 15 분 동안 담가 내부 (30 %의 과산화수소와 황산의 혼합물을 3 일) 피라나 용액을 사용하여 청소한다. </li><li> 탈 이온수로 씻어. 질소 총을 사용하여 건조 불어. </li><li> 유리 데시 케이 터에 웨이퍼를 놓습니다. 데시 케이 터에 제 (트리클로로)를 해제 한 방울 (20 방울 = 1 ml)에 추가한다. </li><li> 게이지가 -762 토르 표시 될 때까지 데시 케이 터를 펌프와 5 시간 동안 기다립니다. </li><li> 박리제로 처리 된 웨이퍼 아웃 보자. </li></ol></li><li> PDMS 필름의 제조 (나노 임프린트의 몰드로 사용) <ol><li> 실리콘 엘라스토머 염기 10g 및 경화제의 1g을 단다. </li><li> 같은 유리 비커에 추가. </li><li> STI는R 및 5 분 동안 유리 막대로 혼합한다. </li><li> 게이지가 모든 갇힌 공기 방울을 펌프 -762 토르 표시 될 때까지 진공 데시 케이 터에 혼합물을 넣어. </li><li> 처리 한 4 인치 실리콘 웨이퍼 상에 균등하게 확산. </li><li> PDMS 막을 경화 80 ° C에서 7 시간 동안 진공 오븐에서 위에 PDMS와 웨이퍼를 굽는다. </li></ol></li></ol> 2. (마스터 금형에서 중복) 나노 임프린트 몰드를 준비 <ol><li> 1500 rpm에서 30 초 동안 깨끗한 빈 실리콘 웨이퍼 상에 UV 경화성 레지스트 열두 방울 (20 방울 = 1 mL) 중 (15.2 %)을 스핀. </li><li> 조심스럽게 처리 한 실리콘 웨이퍼 오프 PDMS 막의 일부를 박리. </li><li> 경화 저항 자외선에 PDMS 필름을 넣고는 UV가 다음 5 분 레지스트를 벗겨 흡수 할 수 있습니다. </li><li> 두 번 같은 PDMS 막 위에 2.1-2.3 반복한다. 자외선은 각각 3 분 1 분 동안 저항을 사용하여 흡수시킬 것. </li><li> 실리콘 마스터 몰드에 (세 시간 자외선 흡수에 저항 후) PDMS 필름을 놓습니다. </li><li> 질소 환경 챔버에 넣어. </li><li> 5 분 동안 샘플을 치료하는 UV 램프를 켭니다. </li><li> PDMS 필름을 벗겨. UV 경화는 마스터 몰드의 네가티브 패턴을 유지할 PDMS 레지스트. </li><li> 사용 RF O 2 플라즈마 PDMS 몰드를 치료한다. (RF 전력 : 30 W, 압력 : 260 mTorr의 시간 : 1 분) </li><li> 2 시간 동안 박리제 한 방울 (20 방울 = 1 ml)로 진공 챔버에 PDMS 몰드를 놓는다. </li></ol> 3. 나노 임프린트 패턴 전송 <ol><li> 기판 상에 PMMA의 팔 방울 (20 방울 = 1 ㎖) (996k, 3.1 %)를 스핀은 3,500 rpm에서 50 초 동안 각인합니다. </li><li> 120 ℃에서 5 분 동안 열판을 굽는다. </li><li> 시료가 식을 때까지 기다립니다. </li><li> 동일 기판 상에 UV 여덟 방울 (20 방울 = 1 ㎖) 경화성은 (3.9 %)을 레지스트 스핀. </li><li> 샘플 (UV 모두 저항 및 PMMA)에 PDMS 몰드 (단계 2에서 제조)를 놓습니다. </li><li> 질소 환경 챔버에 넣어.</li><li> 5 분 동안 치료하는 UV 램프를 켭니다. </li><li> 필 오프 샘플 PDMS 몰드와 PDMS 몰드의 패턴 샘플에 전사 얻는다. </li></ol> 4. CR의 리프트 오프 (lift-off) 공정 <ol><li> 잔류 자외선의 레지스트 층과 PMMA를 반응성 이온 에칭 참고 : ICP 기계에 대한 SOP는 https://www.nanocenter.umd.edu/equipment/fablab/sops/etch-07/Oxford%20Chlorine%20Etcher%20SOP.pdf에서 찾을 수 있습니다 <ol><li> RIE ICP 시스템에 로그인합니다. </li><li> 빈 4 인치 실리콘 웨이퍼를로드합니다. 10 분 동안 깨끗한 레시피를 실행합니다. </li><li> 빈 실리콘 웨이퍼를 꺼내. </li><li> 다른 깨끗한 실리콘 웨이퍼 상에 샘플을 장착하고 시스템에로드합니다. </li><li> 자외선은 2 분 동안 에칭 레시피를 저항 실행 (제조법은 표 1에서 찾아 볼 수있다). </li><li> 샘플을 가져 가라. 빈 4 인치 실리콘 웨이퍼를로드합니다. 다시 실행 깨끗한 레시피를 10 분 동안 (표 1에서 찾아 볼 수있다). </li><li> 깨끗한 실리콘 웨이퍼 상에 샘플을 탑재하고 시스템에로드. </li><li> 2 분 동안 (표 1에서 찾을 수 있습니다) PMMA 에칭 레시피를 실행합니다. 참고 : 이제 잔류 에칭 된 레지스트 및 기판이 노출되어있다. </li></ol></li><li> CR E - 빔 증발 <ol><li> 전자 빔 증발기에 로그인합니다. </li><li> 챔버에 CR 금속 소스 및 샘플을로드합니다. </li><li> 두께 (20 ㎚) 및 증착 속도 (/ 초 0.03 nm의)를 설정합니다. </li><li> 필요한 진공 (10-7 토르)까지 실을 펌프하는 것은 도달한다. </li><li> 증착 프로세스를 시작한다. </li><li> 증착이 완료된 후 샘플을 가져 가라. </li></ol></li><li> 리프트 오프 (lift-off) CR 절차 <ol><li> 5 분 동안 초음파 교반 아세톤에 시료를 담그. </li><li> 아세톤, 메탄올, 이소프로판올로 세척하여 샘플을 청소합니다. 참고 : 전원이 해제됩니다 레지스트 및 기판 에칭 CR 마스크를 형성에 CR 증발. </li></ol></li></ol> 5. 이산화 티탄 출발지osition <ol><li> 로드 샘플. </li><li> 직류 마그네트론 스퍼터링 장치에 대한 매개 변수를 설정 <ol><li> 1.5 mTorr 이하의 챔버 압력, 100 SCCM의 아르곤 흐름과 130 W.의 스퍼터링 전력을 사용 </li><li> 27 ° C의 온도 및 20 rpm의 단계 회전 수를 사용한다. </li></ol></li><li> 스퍼터 공정을 시작하고 원하는 두께로 중지합니다. </li><li> 샘플을 가지고 3 시간 동안 300 ℃에서 산소 환경에서 이산화 티탄 필름을 어닐링. </li></ol> 6. 고 대비 격자 에칭 <ol><li> 유도 결합 플라즈마 (ICP), 반응성 이온 에칭 (RIE) 장치에 로그인. </li><li> 이산화 티탄 에칭 <ol><li> 빈 4 인치 실리콘 웨이퍼를 적재. </li><li> 시작하고 깨끗한 레시피를 실행 10 분 동안 (표 1에서 찾아 볼 수있다). </li><li> 빈 웨이퍼를로드 언로드 및 CR 마스크와 샘플을로드합니다. </li><li> 에칭 시간을 설정합니다. 이산화 티탄 에칭 레시피를 시작합니다. 에칭 공정 의지 자동matically 중지합니다. </li><li> 샘플을 언로드합니다. </li></ol></li><li> SiO2를 에칭 <ol><li> SiO2를 에칭 조리법을 사용 제외 단계를 반복 5.2. </li></ol></li></ol> 7. 반사율 측정 <ol><li> 로그인 및 측정 시스템을 켭니다. </li><li> 샘플 홀더에 반사율 표준 거울을 놓고 광학 경로를 맞 춥니 다. </li><li> 100 %의 반사율을 보정 시스템. </li><li> 반사율 표준 거울을 벗고 HCG를 놓습니다. </li><li> HCG의 반사율을 측정합니다. </li><li> 데이터를 저장하고 측정 시스템의 로그 아웃. </li></ol>

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The authors have nothing to disclose.

우선, 이산화 티탄 막의 품질 HCG 성능에 매우 중요하다. 이산화 티탄 막은 적은 손실 및 표면 거칠기를 갖는 경우, 반사율 피크는 높을 것이다. 광학 모드가 한정 HCG의 평탄한 야기하고 넓은 반사 밴드를 제공 할 수있는 인덱스 높은 콘트라스트에 의해 향상되기 때문에 더 높은 굴절률과 이산화 티탄 막도 바람직하다. 둘째로, 제조 오차 HCG에 상당한 ?...

현대 사회는 재생 가능한 에너지 원으로 에너지 소비의 상당 부분을 움직이지 않고 생존 할 것이다. 이 일어날 수 있도록하기 위해, 우리는 가까운 미래에 석유 기반 에너지 원보다 낮은 비용으로 신 재생 에너지를 수확 할 수있는 방법을 찾을 수있다. 태양 에너지는 지구상에서 가장 풍부한 신 재생 에너지입니다. 진행됨 많은 태양 에너지를 수확하여 이루어진 것을에도 불구하고, 석유 계 에너지 원과 경쟁 여전히 매우 도전적이다. 태양 전지의 효율을 개선하는 것은 태양 에너지 수확의 시스템 비용을 절감 할 수있는 가장 효율적인 방법 중 하나이다. 그것이 고가 탠덤 다중 접합 태양 전지 (2)을 악용 경제성하므로 광학 렌즈 및 접시 반사기는 일반적으로, 작은 면적의 태양 전지에 태양 광이 입사 높은 농도를 달성하기 위해 가장 집중된 광 (CPV) 시스템 (1)에 사용되는 CPV 시스템 및 합리적인 유지동시에 비용. 그들은 일반적으로 더 넓은 태양 스펙트럼 응답 및보다 전반적으로 높은 변환 효율을 갖지만 그러나, 통상 태양 전지의 대 면적 분할을 필요로 가장 비 농축 광전지 시스템의 경우, 고가의 탠덤 태양 전지는, 혼입 될 수 없다 단일 접합 태양 전지 3. 최근 평행 스펙트럼 분할 광학계의 도움 (즉 분산 요소)와, 병렬 스펙트럼 분할 광전지 기술 4 만들었다 그것을 가능한 유사하거나 더 나은 스펙트럼 범위와 변환 효율이 고가의 탠덤 태양 전지를 사용하지 않고 달성 될 수있다. 다른 태양 스펙트럼 대역으로 분할 될 수 있고, 각 대역은 흡수되고 특화된 단일 접합 태양 전지에 의해 전기로 전환시킬 수있다. 이러한 방식으로, CPV 시스템의 비싼 탠덤 태양 전지는 단일 접합 태양 전지의 병렬 분포로 대체 될 수있다성능에 타협하지 않고들. 이 보고서에서 설계된 분산 요소는 개선 된 태양 광 전기 변환 효율 및 비용 절감을위한 병렬 스펙트럼 분리를 실현할 (접시 반사기에 기초하는) 반사 CPV 시스템에 적용될 수있다. 적층 높은 콘트라스트 격자 (HCG)도 5는 광 대역 반사기로 일 HCG의 각 계층을 설계함으로써 분산 요소로서 사용된다. 구조와 분산 요소의 매개 변수가 수치 적으로 최적화되어 있습니다. 또한, 유전체를 사용하여 분산 요소에 대한 높은 콘트라스트 격자의 제작 (이산화 티탄), 스퍼터링, 나노 임프린트 리소그래피 (6) 및 반응성 이온 에칭이 연구되고 설명된다.

<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.

도 1은 농축 광전지 시스템에서 분산 요소 (다층 높은 콘트라스트 격자 (HCG))의 구현을 도시한다. 태양 광은 제 차 미러에 의해 반사 된 빔이 반사되고, 다른 파장의 상이한 대역들로 분할되어 반사 분산 요소에 충돌한다. 각 대역은 전기 가장 흡수 및 전환 용 태양 전지 어레이상의 특정 위치에 충돌한다. 본 시스템의 핵심은 설계 및 HCG의 여러 층으로 구성되는 분산 요소의 구현이다. <...

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.

집중 태양 광 발전 시스템의 스펙트럼 분할 흩어 요소에 대한 고 대비 격자의 제작

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

Research

JoVE Journal

Engineering

10.6K 조회수.  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. 

비디오: 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.

빠른 III-V 족 이종 특성에 대한 전자 채널링 대비 이미징

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

연구

공학

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.

개별 나노 입자의 3D 원소 매핑에 대한 에너지 분산 X 선 단층 촬영

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.

멀티 코어 섬유에 브래그 격자를 작성

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.

완전 해결 가공 된 무기 나노 결정 태양 광 발전 장치의 제작

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.

시간 해결 전자 전도도를 통해 박막 태양 광 재료의 재조합 역학

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.

고농도 현탁액의 유변학 적 특성에 도전 - 스크린 인쇄 실버 페이스트에 대한 사례 연구

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.

에 의한 나노 구조 산화 이트륨 안정화 지르코니아 (YSZ) 비계의 고온 제작<em&gt; 시츄</em&gt; 탄소 템플릿 생성 크 세로 겔

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.

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.

실험실 번개 아크의 광대역 고분해능 방출 스펙트럼을 기록하는 방법

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.

흐름 기반 Dielectrophoresis: 고성능 솔루션 처리 나노와이어 소자의 제조에 대 한 낮은 비용 방법

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