Questo lavoro è fondata dal tedesco Research Foundation (DFG) (Contratto CH 943/2-1). Gli autori desiderano ringraziare Wolfgang Dittus, e Stefan Paetel dal Zentrum für Sonnenenergie-und Wasserstoff-Forschung Baden-Württemberg per la preparazione dello strato di assorbitore CIGS per questo lavoro.

1. CIGS Layer Deposition <ol><li> Polverizzazione catodica-deposito 500 nm di molibdeno (back strato di contatto) su una soda lime substrato di vetro di spessore di 3 mm (SLG). </li><li> Co-evaporare 2 micron di CIGS in CIGS inline processo multistadio 24. Le CIGS ottenuti strato depositato sul Mo contatto retro è mostrato in Figura 1. </li><li> Misurare la composizione integrale di strato CIGS per fluorescenza a raggi X spettrometria (XRF). La composizione CIGS ottenuto è mostrato in Tabella 1. </li></ol> 2. Site-specific Campioni Fabrication per analisi APT <ol><li> Tagliare una griglia TEM Mo in due metà per ottenere una fila di perni diversi, essendo il supporto per i campioni successivi. Montare la metà griglia TEM su un supporto conico e le estremità dei perni di elettrolucidatura in peso 5. % NaOH fino a un diametro di punta &lt;2 micron. Il processo può essere ragionevole controllato utilizzando uno stereoscopio. Poi montare la griglia elettrolitica su un altro supporto di tcappello è ottimizzato per sequenziale FIB, TEM, EBSD, e la caratterizzazione APT. </li><li> Mill due trincee nella CIGS a film sottile utilizzando FIB per ottenere uno scarico (Figura 2a). Fare un primo libero-taglio sul lato sinistro del pezzo. </li><li> Fissare il micromanipolatore per il pezzo depositando un Pt saldatura da fascio ionico indotto deposizione di vapore chimico. Poi, fare la finale di libero taglio sul lato opposto e lift-out il pezzo free-standing (Figura 2b). </li><li> Tagliate ora i perni taglienti della TEM Mo mezza griglia per un cuneo (2-3 micron di diametro) con un buon misto per il pezzo estratto. Montare il pezzo sui perni utilizzando Pt deposizione (Figura 2c). Rendono un free-cut per ottenere infine, solo una piccola parte dello spezzone (circa 2 micron) sulla parte superiore del perno Mo. Successivamente montare il supporto griglia a testa in giù e colmare il divario tra il perno di Mo e il pezzo montato con Pt. Perseguire la stessa procedura con il pezzo rimanente. Per maggiori dettagli su l&#39;ascensore-outprocedura, il lettore può consultare i seguenti riferimenti 18,25. </li><li> Posizionare la griglia verticale e pulire la sezione trasversale dello spezzone (scegliere il sito con diluente Pt saldatura) con una tensione di accelerazione e bassa corrente di fascio (5 kV e &lt;50 pA) nel FIB. Così si ottiene una superficie liscia e meno contaminazione dovuta Ga + impianto, che è richiesto per misurazioni EBSD. </li><li> Dalla misura EBSD effettuata sulla sezione trasversale scegliere un GB di interesse. L&#39;orientamento della GB è preferibile essere perpendicolare rispetto alla direzione di analisi nella sonda atomo (asse z) per ridurre l&#39;effetto di ingrandimento locale 26, che è descritta più in dettaglio nella parte discussione. Uno spazio adeguato con un GB è evidenziato in Figura 2d. </li><li> Eseguire una fresatura anulare nella zona del GB selezionata al punto 2.6) per formare una punta acuminata. Il raggio di curvatura deve essere abbastanza piccolo (&lt;100 nm) per ulteriori TEM investigationi. Per raggiungere questo obiettivo, ridurre il diametro interno della fresatura anulare schema passo passo (figura 2e) e contemporaneamente visualizzarne la punta sagomatura da elettroni secondari (SE). Così si può correggere spostamenti del fascio o regolare la dima di fresatura per rimuovere le irregolarità sulla punta come ripple o rideposizione di materiali derivanti da diverso polverizzazione dei rendimenti, shadowing effetti ecc. </li><li> Localizzare la posizione precisa della GB rispetto al vertice della punta utilizzando lo strumento TEM (vedi figura 2f), sapendo che rispetto ad altri materiali (come superleghe) la CIGS GBS non sono visibili in SEM. </li><li> Sapere esattamente dove la GB si trova all&#39;interno della punta APT, trasferire il campione di nuovo al FIB e continuare a fresare il campione di situare la GB al massimo di 200 nm sotto l&#39;apice della punta. In questa fase, la macinazione avviene a bassissima kV (5 kV) e bassa corrente (&lt;50 pA). Infatti, l&#39;obiettivo è non solo di localizzare il più vicino GB to l&#39;apice della punta, ma anche per ridurre il danno Ga + della punta APT durante questa procedura. Concomitanza alla fresatura basso kV, visualizzare la forma della punta APT in SEM e controllare la quantità di materiale che deve essere rimosso dal vertice della punta (Figura 2g). </li><li> Trasferire nuovamente il campione alla TEM e controllare la posizione del GB rispetto al vertice della punta. Fai una foto panoramica del campione (Figura 2h) per ottenere una conoscenza precisa circa la posizione GB, l&#39;evoluzione del diametro di campione e la metà gambo angolo. Ciò è necessario per conseguire una ricostruzione ottimale dei dati APT. Inoltre, utilizzare bassi ingrandimenti e tempi di esposizione ridotti di minimizzare fascio di elettroni indotti danni e contaminazioni C che può portare ad un tasso di fallimento superiore nelle misure APT. </li></ol> 3. Analisi APT in un salto 3000X Sistema HR CAMECA <ol><li> Montare il campione nella stiva APTER. Poi caricare il disco preparato in uno dei quattro caroselli disponibili. </li><li> Inserire la giostra contenente il puck campione all&#39;interno della serratura carico e iniziare a pompare la serratura carico. Quando il vuoto all&#39;interno della serratura carico è ~ 10 -7 Torr, inserire il carosello all&#39;interno della camera buffer. </li><li> Dopo aver atteso ca. 1 hr per ripristinare il vuoto nella camera di transito (~ 7x10 -9 Torr), trasferire il campione dalla camera tampone alla principale camera di analisi. Questo è fatto con un asta trasferimento orizzontale, che è un dispositivo ad azionamento manuale. </li><li> Prima dell&#39;avvio della misura all&#39;interno della APT, raffreddare la temperatura a 60 K. Le basse temperature evitare la diffusione degli atomi sulla superficie del campione durante l&#39;analisi. Notiamo che 60 K è la temperatura impostata e non la reale temperatura misurata sulla punta APT, che dovrebbe essere più elevato a causa del calore laser del provino. Come proposto da Kellog et al. 27, questa temperatura può essere stimata tenendo conto del grado di-stato-rapporto di carica. Purtroppo, in questo lavoro la reale temperatura delle punte potrebbe non essere calcolato soprattutto perché il campo evaporazione del materiale CIGS è sconosciuto. </li><li> Esperimenti di APT sono svolte in modalità laser utilizzando un laser verde con una lunghezza d&#39;onda di circa 532 nm e 12 di lunghezza impulsi psec. </li></ol> 4. Ricostruzione di dati APT <ol><li> Aprire il file RHIT (dati grezzi ottenuti direttamente dopo misurazioni di APT), con visualizzazione integrata di CAMECA e software di analisi (IVAS 3.6.2) 28 generalmente utilizzato per ricostruire la mappa 3D. </li><li> Eseguire la ricostruzione della mappa 3D utilizzando le seguenti otto passaggi 28: <ol><li> Fase 1 - Impostazione che è di sola lettura riquadro dando tutti i dettagli circa la natura e il contenuto dello studio selezionato. </li><li> Fase 2 - Seleziona Gamma sequenza di ioni. Questo passaggio definisce la gamma ionico sequenza rispetto al provino-Tensione da selezionare nei dati ricostruendo. </li><li> Fase 3 - Scegliere il rilevatore di ROI. Questo passaggio dà la possibilità di rimuovere gli ioni situati esternamente alla rilevatore ROI (nero ellisse sul istogramma evento rivelatore). </li><li> Passo 4 - TOF correzioni. Questo passaggio elabora la tensione, il tempo di volo (TOF), e la planarità del rivelatore (&#39;ciotola correzione&#39;) correzioni per l&#39;analisi. </li><li> Fase 5 - Calibrazione di massa. La posizione del picco misurata nello spettro di massa analizzato è calibrato con noti isotopi / carica stati. </li><li> Fase 6 - Intervallo di assegnazione di ioni. In questa fase i picchi nello spettro di massa sono assegnati ai campi di isotopi di elementi. </li><li> Fase 7 - Ricostruzione. Questo passaggio si applica uno dei tre metodi di ricostruzione per i dati acquisiti: Metodo di tensione, il metodo di attacco ad angolo o il metodo punta-profilo. L&#39;ultimo è usato in studio per ricostruire il nostro 3D-mappa. Questo metodo richiede una immagine SEM o TEM della TIp, come mostrato nella figura 2g e 2h Figura. Il raggio della punta in qualsiasi punto nella ricostruzione è definito da una interpolazione lineare tra una serie di punti definiti nell&#39;immagine SEM. </li><li> Fase 8 - Conferma. In questa fase, l&#39;anteprima create nella scheda ricostruzione viene convertito un&#39;analisi salvata. </li></ol></li></ol>

<ol>
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Sci. 116, 273-301 (1982).</li><li>Letellier, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Etude des joints de grains et interphases dans les superalliages Astroloy par microscopie electronique et tomographie atomique [dissertation]. , (1994).</li><li>Hoummada, I., Mangelinck, K., Chow, D., Lee, J., Bernardini, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Original+methods+for+diffusion+measurements+in+polycrystalline+thin-films.">Original methods for diffusion measurements in polycrystalline thin-films.</a> Defect and Diffusion Forum. 322, 129-150 (2012).</li></ol>

<p class="jove_content"&gt; Gli autori non hanno nulla da rivelare.</p&gt;

Nel presente lavoro, abbiamo presentato i risultati APT su un HAGB casuale in CIGS, un materiale semiconduttore composto utilizzato per applicazioni fotovoltaiche. Inoltre, abbiamo anche dimostrato che l&#39;APT in combinazione con tecniche complementari, come EBSD e TEM, è un potente strumento per chiarire le proprietà di struttura-composizione relazione per le celle solari CIGS. Purtroppo, la correlazione tra APT e EDX / EELS in TEM non era possibile perché in primo luogo, EDX / EELS non ha una risoluzione sufficie...

<html> Celle solari a film sottile basati sulla calcopirite strutturato semiconduttori composti di Cu (In, Ga) Se 2 (CIGS) come il materiale assorbitore sono in fase di sviluppo per più di due decenni a causa della loro elevata efficienza, resistenza alla radiazione, stabile a lungo termine prestazioni e bassi costi di produzione 1-3. Queste celle solari possono essere fabbricate con solo poco consumo di materiale a causa delle proprietà favorevoli ottiche dello strato assorbitore CIGS, ovvero un bandgap diretto e un elevato coefficiente di assorbimento 1,2. Film assorbitore di pochi micrometri di spessore sono sufficienti a generare un elevato fotocorrente. Poiché i percorsi di diffusione dei portatori di carica fotogenerati agli elettrodi sono relativamente brevi, assorbitori CIGS possono essere prodotti in forma policristallina. L&#39;efficienza massima di un Cu (In, Ga) Se 2 (CIGS) cella solare realizzato finora è 20,4% 4, che è il valore più alto tra tutte le celle solari a film sottile. ove_content &quot;&gt; Per stabilire ulteriormente la tecnologia fotovoltaica a film sottile CIGS, sia la riduzione dei costi di produzione e il miglioramento dell&#39;efficienza delle celle solari sono essenziali. Quest&#39;ultimo è fortemente dipendente dalla microstruttura e la composizione chimica dello strato di assorbitore CIGS. Interfacce interne, in particolare i bordi di grano (GBS) entro l&#39;assorbitore, gioca un ruolo fondamentale, in quanto possono influenzare il trasporto di portatori di carica fotogenerati. Uno dei principali problemi irrisolti per quanto riguarda le celle solari CIGS è la natura benigna di CIGS GB, cioè policristallino CIGS film assorbitore producono efficienze delle celle in sospeso, nonostante una elevata densità di GBS e reticolo difetti. Diversi autori hanno studiato GB in CIGS film solar-grade rispetto alle loro proprietà elettriche 5,6, carattere e misorientation 7-9 così come impurità segregazione 10-13. Tuttavia, un chiaro legame tra questi Propertieses potrebbe essere stabilito fino ad ora. In particolare, vi è una sostanziale mancanza di informazioni circa la composizione chimica locale e contenuto di impurità del GB. Negli ultimi due decenni, Atom Probe Tomography (APT) è emerso come uno dei più promettenti tecniche di nano-analitiche 14-17. Fino a tempi recenti studi APT di celle solari sono state in gran parte limitato da difficoltà nel processo di preparazione del campione e la limitata capacità di analizzare materiali semiconduttori che utilizzano sonde atomo pulsata tensione convenzionali. Queste restrizioni sono state in gran parte superato dallo sviluppo del &#39;metodo lift-out&#39; sulla base di un fascio ionico (FIB) fresatura mirata 18 e l&#39;introduzione del laser pulsato APT 16. Diversi articoli sulla caratterizzazione APT di celle solari CIGS sono state pubblicate 19-23, che sono fortemente incoraggiante per ulteriori indagini. Questo documento fornisce una linea guida su come studiare interna interfaces in CIGS a film sottile celle solari da parte della sonda tecnica di tomografia atomo.

atom probe tomography studies on the cu(in,ga)se2 grain boundaries

Rispetto alle tecniche esistenti, atomo sonda tomografia è una tecnica unica in grado di caratterizzare chimicamente le interfacce interne alla nanoscala e in tre dimensioni. Anzi, APT possiede elevata sensibilità (dell&#39;ordine di ppm) e ad alta risoluzione spaziale (sub nm). Notevoli sforzi sono stati fatti qui per preparare una punta APT che contiene il bordo di grano desiderato con una struttura nota. Infatti, site-specific di preparazione del campione utilizzando in combinazione concentrata di litio-beam, electron backscatter diffrazione, e microscopia elettronica a trasmissione viene presentato in questo lavoro. Questo metodo permette di bordi di grano selezionate con una struttura nota e la posizione in Cu (In, Ga) Se due film sottili per essere studiati da tomografia atomo sonda. Infine, discuteremo i vantaggi e gli svantaggi di usare la sonda tecnica di tomografia atomo di studiare i bordi di grano in Cu (In, Ga) Se 2 celle solari a film sottile.

La figura 3 mostra una vista laterale (xz slice) mappa elementare del casuale ad alto angolo GB (HAGB) 28.5 ° - &lt;511&gt; cucciolo selezionato nella figura 2 con il metodo di preparazione del sito-specifica. Co-segregazione di Na, K e O in una CIGS HAGB viene mappato direttamente usando APT. Queste impurità più probabile diffusi del substrato SLG nello strato assorbitore durante la deposizione dello strato di CIGS a ~ 600 ° C. La Fig...

Watch this Scientific Journal Video about Atom Probe Tomography Studies on the CuIn,GaSe2 Grain Boundaries at JoVE.com

Atom Probe Tomography Studies on the CuIn,GaSe2 Grain Boundaries

In questo lavoro, si descrive l&#39;uso della tecnica tomografia atomo-sonda per studiare i bordi grano dello strato assorbitore in una cella solare CIGS. Un nuovo approccio per preparare le punte della sonda atomo contenenti il ​​bordo di grano desiderata con una struttura nota è anche presentato qui.

Atom Probe Studi tomografia sul Cu (In, Ga) se<sub&gt; 2</sub&gt; Bordi di grano

Compared with the existent techniques, atom probe tomography is a unique technique able to chemically characterize the internal interfaces at the ...

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Atom Probe Tomography Studies on the Cu(In,Ga)Se2 Grain Boundaries

12.6K Views.  Max-Planck-Institut für Eisenforschung GmbH. In questo lavoro, si descrive l'uso della tecnica tomografia atomo-sonda per studiare i bordi grano dello strato assorbitore in una cella solare CIGS. Un nuovo approccio per preparare le punte della sonda atomo contenenti il ​​bordo di grano desiderata con una struttura nota è anche presentato qui.

Video: Atom Probe Tomography Studies on the CuIn,GaSe2 Grain Boundaries

Scanning-probe Single-electron Capacitance Spectroscopy

The integration of low-temperature scanning-probe techniques and single-electron capacitance spectroscopy represents a powerful tool to study the electronic quantum structure of small systems - including individual atomic dopants in semiconductors. Here we present a capacitance-based method, known as Subsurface Charge Accumulation (SCA) imaging, which is capable of resolving single-electron charging while achieving sufficient spatial resolution to image individual atomic dopants. The use of a capacitance technique enables observation of subsurface features, such as dopants buried many nanometers beneath the surface of a semiconductor material1,2,3. In principle, this technique can be applied to any system to resolve electron motion below an insulating surface.
As in other electric-field-sensitive scanned-probe techniques4, the lateral spatial resolution of the measurement depends in part on the radius of curvature of the probe tip. Using tips with a small radius of curvature can enable spatial resolution of a few tens of nanometers. This fine spatial resolution allows investigations of small numbers (down to one) of subsurface dopants1,2. The charge resolution depends greatly on the sensitivity of the charge detection circuitry; using high electron mobility transistors (HEMT) in such circuits at cryogenic temperatures enables a sensitivity of approximately 0.01 electrons/Hz&frac12; at 0.3 K 5.

Scanning-probe single-electron capacitance spectroscopy facilitates the study of single-electron motion in localized subsurface regions. A sensitive charge-detection circuit is incorporated into a cryogenic scanning probe microscope to investigate small systems of dopant atoms beneath the surface of semiconductor samples.

Scansione-sonda a singolo elettrone Capacità Spettroscopia

The integration of low-temperature scanning-probe techniques and single-electron capacitance spectroscopy represents a powerful tool to study the ...

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The Measurement of Unsteady Surface Pressure Using a Remote Microphone Probe

Microphones are widely applied to measure pressure fluctuations at the walls of solid bodies immersed in turbulent flows. Turbulent motions with various characteristic length scales can result in pressure fluctuations over a wide frequency range. This property of turbulence requires sensing devices to have sufficient sensitivity over a wide range of frequencies. Furthermore, the small characteristic length scales of turbulent structures require small sensing areas and the ability to place the sensors in very close proximity to each other. The complex geometries of the solid bodies, often including large surface curvatures or discontinuities, require the probe to have the ability to be set up in very limited spaces. The development of a remote microphone probe, which is inexpensive, consistent, and repeatable, is described in the present communication. It allows for the measurement of pressure fluctuations with high spatial resolution and dynamic response over a wide range of frequencies. The probe is small enough to be placed within the interior of typical wind tunnel models. The remote microphone probe includes a small, rigid, and hollow tube that penetrates the model surface to form the sensing area. This tube is connected to a standard microphone, at some distance away from the surface, using a "T" junction. An experimental method is introduced to determine the dynamic response of the remote microphone probe. In addition, an analytical method for determining the dynamic response is described. The analytical method can be applied in the design stage to determine the dimensions and properties of the RMP components.

Here, we present a protocol to measure, with high spatial resolution, the unsteady surface pressure in turbulent flows. This method demonstrates the construction of a remote microphone probe (RMP) and the determination of its frequency-dependent, complex transfer function. An analytical determination of the dynamic response is presented and validated.

La misurazione della pressione instabile superficie utilizzando una sonda microfono remoto

Microphones are widely applied to measure pressure fluctuations at the walls of solid bodies immersed in turbulent flows. Turbulent motions with various ...

Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy (ATOM)

Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the main trend in the advanced development of flow cytometry. Notably, adding high-resolution imaging capabilities allows for the complex morphological analysis of cellular/sub-cellular structures. This is not possible with standard flow cytometers. However, it is valuable for advancing our knowledge of cellular functions and can benefit life science research, clinical diagnostics, and environmental monitoring. Incorporating imaging capabilities into flow cytometry compromises the assay throughput, primarily due to the limitations on speed and sensitivity in the camera technologies. To overcome this speed or throughput challenge facing imaging flow cytometry while preserving the image quality, asymmetric-detection time-stretch optical microscopy (ATOM) has been demonstrated to enable high-contrast, single-cell imaging with sub-cellular resolution, at an imaging throughput as high as 100,000 cells/s. Based on the imaging concept of conventional time-stretch imaging, which relies on all-optical image encoding and retrieval through the use of ultrafast broadband laser pulses, ATOM further advances imaging performance by enhancing the image contrast of unlabeled/unstained cells. This is achieved by accessing the phase-gradient information of the cells, which is spectrally encoded into single-shot broadband pulses. Hence, ATOM is particularly advantageous in high-throughput measurements of single-cell morphology and texture &#8211; information indicative of cell types, states, and even functions. Ultimately, this could become a powerful imaging flow cytometry platform for the biophysical phenotyping of cells, complementing the current state-of-the-art biochemical-marker-based cellular assay. This work describes a protocol to establish the key modules of an ATOM system (from optical frontend to data processing and visualization backend), as well as the workflow of imaging flow cytometry based on ATOM, using human cells and micro-algae as the examples.

Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy ATOM

This protocol describes the implementation of an asymmetric-detection time-stretch optical microscopy system for single-cell imaging in ultrafast microfluidic flow and its applications in imaging flow cytometry.

Citometria del flusso microfluidico di imaging mediante rilevazione asimmetrica Microscopia ottica di stretching (ATOM)

Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the ...

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for Cu(In,Ga)Se2 Solar Cells

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction of degradation mechanisms and prevention of module field failure can consequently decrease investment risks as well as increase the electricity yield. An improved knowledge level can for these reasons significantly decrease the total costs of PV electricity. 
In order to better understand and minimize the degradation of PV modules, the occurring degradation mechanisms and conditions should be identified. This should preferably happen under combined stresses, since modules in the field are also simultaneously exposed to multiple stress factors. Therefore, two 'Combined Stress test with in situ measurement' setups have been designed and constructed. These setups allow the simultaneous use of humidity, temperature, illumination, and electrical biases as independently controlled stress factors on solar cells and minimodules. The setups also allow real-time monitoring of the electrical properties of these samples. This protocol presents these setups and describes the experimental possibilities. Moreover, results obtained with these setups are also presented: various examples about the influence of both deposition and degradation conditions on the stability of thin film Cu(In,Ga)Se2 (CIGS) as well as Cu2ZnSnSe4 (CZTS) solar cells are described. Results on the temperature dependency of CIGS solar cells are also presented.

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for CuIn,GaSe2 Solar Cells

Two &#39;Combined Stress test with in situ measurement&#39; setups, which allow real-time monitoring of accelerated degradation of solar cells and modules, were designed and constructed. These setups allow the simultaneous use of humidity, temperature, electrical biases, and illumination as independently controlled stress factors. The setups and various experiments executed are presented.

In Situ Monitoraggio del degrado prestazioni accelerate di celle e moduli solari: un caso di studio per le celle solari di Cu (In, Ga) Se2

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction ...

Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques

Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared on transparent membranes which are very fragile and difficult to manipulate. We present processes for the fabrication of samples with magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for Lorentz transmission electron microscopy and magnetic transmission x-ray microscopy studies. The samples are prepared on silicon nitride membranes and the fabrication consists of a spin coating, UV and electron-beam lithography, the chemical development of the resist, and the evaporation of the magnetic material followed by a lift-off process forming the final magnetic structures. The samples for the Lorentz transmission electron microscopy consist of magnetic nanodiscs prepared in a single lithography step. The samples for the magnetic x-ray transmission microscopy are used for time-resolved magnetization dynamic experiments, and magnetic nanodiscs are placed on a waveguide which is used for the generation of repeatable magnetic field pulses by passing an electric current through the waveguide. The waveguide is created in an extra lithography step.

A protocol for the fabrication of magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for transmission electron microscopy (TEM) and magnetic transmission x-ray microscopy (MTXM) studies is presented.

Fabbricazione di nanostrutture magnetiche sulle membrane di nitruro di silicio per studi di vortice magnetico utilizzando tecniche di microscopia di trasmissione

Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared ...

Fabrication of Robust Nanoscale Contact between a Silver Nanowire Electrode and CdS Buffer Layer in Cu(In,Ga)Se2 Thin-film Solar Cells

Silver nanowire transparent electrodes have been employed as window layers for Cu(In,Ga)Se2 thin-film solar cells. Bare silver nanowire electrodes normally result in very poor cell performance. Embedding or sandwiching silver nanowires using moderately conductive transparent materials, such as indium tin oxide or zinc oxide, can improve cell performance. However, the solution-processed matrix layers can cause a significant number of interfacial defects between transparent electrodes and the CdS buffer, which can eventually result in low cell performance. This manuscript describes how to fabricate robust electrical contact between a silver nanowire electrode and the underlying CdS buffer layer in a Cu(In,Ga)Se2 solar cell, enabling high cell performance using matrix-free silver nanowire transparent electrodes. The matrix-free silver nanowire electrode fabricated by our method proves that the charge-carrier collection capability of silver nanowire electrode-based cells is as good as that of standard cells with sputtered ZnO:Al/i-ZnO as long as the silver nanowires and CdS have high-quality electrical contact. The high-quality electrical contact was achieved by depositing an additional CdS layer as thin as 10 nm onto the silver nanowire surface.

Fabrication of Robust Nanoscale Contact between a Silver Nanowire Electrode and CdS Buffer Layer in CuIn,GaSe2 Thin-film Solar Cells

In this protocol, we describe the detailed experimental procedure for the fabrication of a robust nanoscale contact between a silver nanowire network and CdS buffer layer in a CIGS thin-film solar cell.

Fabbricazione di robusto contatto nanoscala tra un'elettroda Nanowire d'argento e CdS Buffer Layer in Cu(In,Ga)Se2 thin-film Solar Cells

Silver nanowire transparent electrodes have been employed as window layers for Cu(In,Ga)Se2 thin-film solar cells. Bare silver nanowire electrodes ...

Visualization of Failure and the Associated Grain-Scale Mechanical Behavior of Granular Soils under Shear using Synchrotron X-Ray Micro-Tomography

The rapid development of X-ray imaging techniques with image processing and analysis skills has enabled the acquisition of CT images of granular soils with high-spatial resolutions. Based on such CT images, grain-scale mechanical behavior such as particle kinematics (i.e., particle translations and particle rotations), strain localization and inter-particle contact evolution of granular soils can be quantitatively investigated. However, this is inaccessible using conventional experimental methods. This study demonstrates the exploration of the grain-scale mechanical behavior of a granular soil sample under triaxial compression using synchrotron X-ray micro-tomography (&#956;CT). With this method, a specially fabricated miniature loading apparatus is used to apply confining and axial stresses to the sample during the triaxial test. The apparatus is fitted into a synchrotron X-ray tomography setup so that high-spatial resolution CT images of the sample can be collected at different loading stages of the test without any disturbance to the sample. With the capability of extracting information at the macro scale (e.g., sample boundary stresses and strains from the triaxial apparatus setup) and the grain scale (e.g., grain movements and contact interactions from the CT images), this procedure provides an effective methodology to investigate the multi-scale mechanics of granular soils.

The protocol describes procedures to acquire high-spatial resolution computed tomography (CT) images of a granular soil during triaxial compression, and to apply image processing techniques to these CT images to explore the grain-scale mechanical behavior of the soil under loading.

Visualizzazione del fallimento e del comportamento meccanico associato della scala del grano dei suoli granulari sotto Shear utilizzando la microtografia a raggi X del synchrotron

The rapid development of X-ray imaging techniques with image processing and analysis skills has enabled the acquisition of CT images of granular soils ...

Improving the Combustion Performance of a Hybrid Rocket Engine using a Novel Fuel Grain with a Nested Helical Structure

A technique to improve the combustion performance of a hybrid rocket engine using a novel fuel grain structure is presented. This technique utilizes the different regression rates of acrylonitrile butadiene styrene and paraffin-based fuels, which increase the exchanges of both matter and energy by swirl flow and recirculation zones formed at the grooves between the adjacent vanes. The centrifugal casting technique is used to cast the paraffin-based fuel into an acrylonitrile butadiene styrene substrate made by three-dimensional printing. Using oxygen as the oxidizer, a series of tests were conducted to investigate the combustion performance of the novel fuel grain. In comparison to paraffin-based fuel grains, the fuel grain with a nested helical structure, which can be maintained throughout the combustion process, showed significant improvement in the regression rate and great potential in improvement of combustion efficiency.

A technique utilizing a solid fuel grain with a novel nested helical structure to improve the combustion performance of a hybrid rocket engine is presented.

Migliorare le prestazioni di combustione di un motore a razzo ibrido utilizzando un nuovo grano combustibile con una struttura elicoiale annidata

A technique to improve the combustion performance of a hybrid rocket engine using a novel fuel grain structure is presented. This technique utilizes the ...

Co-localizing Kelvin Probe Force Microscopy with Other Microscopies and Spectroscopies: Selected Applications in Corrosion Characterization of Alloys

Kelvin probe force microscopy (KPFM), sometimes referred to as surface potential microscopy, is the nanoscale version of the venerable scanning Kelvin probe, both of which measure the Volta potential difference (VPD) between an oscillating probe tip and a sample surface by applying a nulling voltage equal in magnitude but opposite in sign to the tip-sample potential difference. By scanning a conductive KPFM probe over a sample surface, nanoscale variations in surface topography and potential can be mapped, identifying likely anodic and cathodic regions, as well as quantifying the inherent material driving force for galvanic corrosion.
Subsequent co-localization of KPFM Volta potential maps with advanced scanning electron microscopy (SEM) techniques, including back scattered electron (BSE) images, energy dispersive spectroscopy (EDS) elemental composition maps, and electron backscattered diffraction (EBSD) inverse pole figures can provide further insight into structure-property-performance relationships. Here, the results of several studies co-localizing KPFM with SEM on a wide variety of alloys of technological interest are presented, demonstrating the utility of combining these techniques at the nanoscale to elucidate corrosion initiation and propagation.
Important points to consider and potential pitfalls to avoid in such investigations are also highlighted: in particular, probe calibration and the potential confounding effects on the measured VPDs of the testing environment and sample surface, including ambient humidity (i.e., adsorbed water), surface reactions/oxidation, and polishing debris or other contaminants. Additionally, an example is provided of co-localizing a third technique, scanning confocal Raman microscopy, to demonstrate the general applicability and utility of the co-localization method to provide further structural insight beyond that afforded by electron microscopy-based techniques.

Kelvin probe force microscopy (KPFM) measures surface topography and differences in surface potential, while scanning electron microscopy (SEM) and associated spectroscopies can elucidate surface morphology, composition, crystallinity, and crystallographic orientation. Accordingly, the co-localization of SEM with KPFM can provide insight into the effects of nanoscale composition and surface structure on corrosion.

Co-localizzazione della microscopia Kelvin Probe Force con altre microscopie e spettroscopie: applicazioni selezionate nella caratterizzazione della corrosione delle leghe

Kelvin probe force microscopy (KPFM), sometimes referred to as surface potential microscopy, is the nanoscale version of the venerable scanning Kelvin ...

Application of Deep Learning-Based Medical Image Segmentation via Orbital Computed Tomography

Recently, deep learning-based segmentation models have been widely applied in the ophthalmic field. This study presents the complete process of constructing an orbital computed tomography (CT) segmentation model based on U-Net. For supervised learning, a labor-intensive and time-consuming process is required. The method of labeling with super-resolution to efficiently mask the ground truth on orbital CT images is introduced. Also, the volume of interest is cropped as part of the pre-processing of the dataset. Then, after extracting the volumes of interest of the orbital structures, the model for segmenting the key structures of the orbital CT is constructed using U-Net, with sequential 2D slices that are used as inputs and two bi-directional convolutional long-term short memories for conserving the inter-slice correlations. This study primarily focuses on the segmentation of the eyeball, optic nerve, and extraocular muscles. The evaluation of the segmentation reveals the potential application of segmentation to orbital CT images using deep learning methods.

Application of Deep Learning-Based Medical Image Segmentation via Orbital Computed Tomography

An object segmentation protocol for orbital computed tomography (CT) images is introduced. The methods of labeling the ground truth of orbital structures by using super-resolution, extracting the volume of interest from CT images, and modeling multi-label segmentation using 2D sequential U-Net for orbital CT images are explained for supervised learning.