Gli autori ringraziano Svilen Bobev per il suo aiuto con gli spettri XRD e K. Booksh per l&#39;assistenza con l&#39;apparecchiatura sputter coater.

1. Sintesi di Tree-come ZnO / CdSSe Nanostrutture <ol><li> Pretrattamento e oro rivestimento di substrati di zaffiro NOTA: Il film oro agisce come catalizzatore nella crescita dei nanofili di ZnO. <ol><li> Pulire le diapositive zaffiro (un-aereo, 10 × 10 × 1 mm) a 99,5% di etanolo con 5 minuti di ultrasuoni per preparare il substrato per Au sputtering. </li><li> Deposito a 10 nm (± 2 nm) pellicola -thick d&#39;oro sulle diapositive zaffiro con un dispositivo a induzione polverizzazione e bersaglio oro. </li></ol></li><li> Sintesi di nanofili di ZnO NOTA: Il passo sonicazione 1.2.2 risultati in ZnO omogenea e carbonio (ZnO / C) della miscela. Dopo la miscelazione, la miscela si trasforma in un colore grigio. Il passo compattazione 1.2.3 assicura che l&#39;aria presente nella miscela e la ZnO e carbonio sono in stretto contatto. Dopo CVD, una pellicola bianca di nanofili di ZnO deve essere depositato sul substrato, lato rivolto verso la barca. <ol><li> Mescolare 1 g di ZnO nanopolveri e Activcarbonio ated (frazione di massa di 50:50) in 10 ml di etanolo al 99,5% e mescolare bene con una spatola. </li><li> Sonicare la miscela in un bagno di acqua a 20 ° C per 30 minuti, e poi asciugare in un forno per ~ 5 ore a 80 ° C. </li><li> Mettere il composto ZnO / C in una barca allumina e compatta bene con una spatola. </li><li> Porre i vetrini zaffiro oro rivestite sulla sommità della barca allumina, con il lato rivestito in oro rivolto verso il basso. Posizionare la barca allumina nel centro del tubo di quarzo in un forno tubolare orizzontale. </li><li> Eliminare il tubo di quarzo per 1 ora con Ar ad un flusso di 40 sccm a temperatura ambiente (RT). Aumentare la temperatura da RT a 900 ° C ad una velocità di 80 ° C / min e mantenere costante la portata di argon. </li><li> Mantenere la temperatura a 900 ° C per 2 ore. Aprire il tubo di quarzo su entrambe le estremità rimuovendo le ingressi gas tappo di gomma e lasciar entrare aria nel tubo per fornire l&#39;ossigeno per la reazione. </li><li> Mantenere la temperatura di reazione a 900 ° C per 3 ore con il rutappi bBER rimossi. Raffreddare a RT ad una velocità di 10 ° C / min. </li><li> Prendere la barca e la slitta fuori dal forno. </li></ol></li><li> Deposizione di rami CdSSe su nanofili di ZnO NOTA: La barca allumina di CdS / SE è stato visualizzato al centro del tubo di quarzo. I nanofili di ZnO preparati sono stati rivolti verso l&#39;alto ed erano 10 cm valle dalla barca. Dopo questa seconda CVD, un arancio / pellicola gialla, che è la nanostruttura ZnO / CdSSe, deve essere depositato sul vetrino. <ol><li> Miscelare 0,5 g di CD e CdSe (CdS / Se) in polvere e (frazione di massa di 50:50) e mettere il composto in una barca di allumina. Compattare bene il composto. </li><li> Posizionare la barca di allumina di CdS / SE e il campione ZnO nanowire precedentemente preparato nel tubo di quarzo. </li><li> Spurgare il tubo con Ar ad un flusso di 40 sccm a temperatura ambiente per 1 ora. Aumentare la temperatura di reazione a 820 ° C ad una velocità di 80 ° C / min. Mantenere la temperatura a 820 ° C per 30 min. </li><li> Raffreddare a RTun tasso di 10 ° C / min. Prendere la barca e la slitta fuori dal forno. </li></ol></li><li> Sintesi dei campioni di controllo: ZnO e CdSSe nanofili <ol><li> Sintetizzare nanofili di ZnO come nella sezione 1.2 nelle stesse condizioni sperimentali. </li><li> Sintetizzare nanofili CdSSe come nella sezione 1.3, nelle stesse condizioni sperimentali, con la stessa quantità di CdS e la composizione CdSe, ma con un pulito, oro rivestite diapositiva zaffiro come substrato invece della diapositiva ZnO-depositato. </li></ol></li></ol> 2. morfologica e cristallografica Caratterizzazione <ol><li> Montare il campione sulla scena SEM con un morsetto e posizionare il campione nella camera a vuoto dello strumento SEM. Prendere immagini SEM in modalità ad alta risoluzione con una distanza di lavoro di 12,0 mm con una tensione di 3 kV e un ingrandimento tra 3,000X e 10.000X 11,12. </li><li> Dai dati EDS con lo stesso campione utilizzando il rivelatore di raggi X alla stessa distanza di lavoro di12.0 mm. Impostare lo strumento in modalità di analisi e regolare la tensione di 20 kV, causando una corrente di 20 a 40 μA 13. </li><li> Raccogliere XRD spettri su un diffrattometro a raggi X in polvere utilizzando filtrata Cu Kα radiazioni (λ = 1,5418 Å) 11,12. </li></ol> 3. PL Emission Spectroscopy e risolte nel tempo PL Lifetime Misure NOTA: spettri PL e il conteggio di singolo fotone tempo-correlato (TCSPC) misurazioni a RT sono state effettuate utilizzando un amplificato Ti: oscillatore zaffiro dopo generazione di seconda armonica (SHG), producendo un treno di 50 impulsi FSEC centrato alla lunghezza d&#39;onda di 400 nm e con una potenza di uscita di 1,76 mW 14. <ol><li> Fissare il campione in un portacampioni che posiziona la faccia campione fino alla laser e al rivelatore. Allineare il laser a concentrarsi sul campione. Misurare gli spettri di emissione PL dei campioni da 500 nm a lunghezze d&#39;onda di 900 nm usando uno spettrometro fibra. </li><li> Utilizzare un rivelatore di singolo fotone (avalanche fotodiodo o tubo fotografico) per misurare il tempo-risolta vite PL con un filtro di vetro di colore e un filtro passa-banda interferenze 500- o 650-nm. </li><li> Inserire ZnO, CdSSe, o ZnO / CdSSe scivola nel supporto del campione. Misurare i nanofili di ZnO puro con il filtro passa-banda da 500 nm e campioni CdSSe o ZnO / CdSSe con un filtro passa-banda da 650 nm. </li><li> Utilizzare un contatore di fotoni sola volta-correlata o di un oscilloscopio veloce per misurare i tempi di vita di fluorescenza di decadimento risolte nel tempo. </li></ol>

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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=Photosensitization+of+ZnO+Nanowires+with+CdSe+Quantum+Dots+for+Photovoltaic+Devices.">Photosensitization of ZnO Nanowires with CdSe Quantum Dots for Photovoltaic Devices.</a> Nano Lett. 7 (6), 1793-1798 (2007).</li><li>Gonzalez-Valls, I., Lira-Cantu, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vertically-aligned+nanostructures+of+ZnO+for+excitonic+solar+cells:+a+review.">Vertically-aligned nanostructures of ZnO for excitonic solar cells: a review.</a> Energy Environ Sci. 2 (1), 19-34 (2009).</li><li>Zhu, G., 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=Synthesis+of+vertically+aligned+ultra-long+ZnO+nanowires+on+heterogeneous+substrates+with+catalyst+at+the+root.">Synthesis of vertically aligned ultra-long ZnO nanowires on heterogeneous substrates with catalyst at the root.</a> Nanotechnology. 23 (5), 055604 (2012).</li><li>Yang, P., 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=Controlled+Growth+of+ZnO+Nanowires+and+Their+Optical+Properties.">Controlled Growth of ZnO Nanowires and Their Optical Properties.</a> Adv. 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I dati e le cifre in questo articolo sono citati dalla letteratura nel campo delle nanotecnologie da Li et al. 17.

L&#39;allineamento verticale di nanofili ZnO (steli) è basato sulla crescita epitassiale sul substrato. Nanofili di ZnO crescono preferenzialmente lungo la &lt;0001&gt; direzione che corrisponde con la periodicità della un-piano di zaffiro 12. Pertanto, il tipo e la qualità del substrato sono molto importanti. Differenti spessori del rivestimento d&#39;oro sul substrato, da 5 nm a 20 nm, sono stati testati e ha mostrato alcuna differenza significativa nella crescita di nanofili di ZnO. La lunghezza dei nan...

ZnO è un semiconduttore II-VI con un band gap (BG) di 3,3 eV, una elevata mobilità elettronica, e 1,2 energia di legame grande eccitone. Si tratta di un materiale semiconduttore abbondante con una pletora di applicazioni attuali e futuri dispositivi ottici, celle solari e fotocatalisi. Tuttavia, ZnO è trasparente, che limita la sua applicazione nel campo spettrale visibile. Pertanto, materiali assorbenti la luce visibile, come i semiconduttori stretta gap 3, 4 molecole di colorante, e polimeri fotosensibili 5, sono spesso stati impiegati per sensibilizzare ZnO di assorbimento della luce visibile. CdS (BG 2.43 eV) e CdSe (BG 1,76 eV) sono comuni II-VI semiconduttori stretta gap e sono stati intensamente studiati. I parametri BG e reticolo della lega ternaria CdSSe possono essere regolate variando i rapporti molari dei componenti VI 6,7. nanocompositi ZnO / CdSSe sono stati segnalati per provocare photov efficienteconversione di energia oltaic 8,9. Combinando il percorso di trasporto degli elettroni efficiente di nanofili di ZnO allineati verticalmente verso un substrato con il migliorato assorbimento della luce visibile dei rami CdSSe portato a trasferimento di elettroni efficace tra lo stelo e rami 9,10. Così, abbiamo sintetizzato un nuovo ZnO / CdSSe nanostruttura ad albero, dove nanofili di ZnO allineati verticalmente sono decorate con rami CdSSe. Questo materiale composito può agire come un blocco di costruzione per nuovi dispositivi di conversione dell&#39;energia solare. Questo protocollo descrive come array di nanofili di ZnO sono coltivate su un substrato di zaffiro da una fase di deposizione di vapore chimico (CVD) da polveri di ZnO e C, seguendo una procedura che è stato precedentemente pubblicato 11. Dopo la crescita di nanofili di ZnO, una seconda fase di CVD è impiegato a crescere rami CdSSe sui nanofili di ZnO. Ci avvaliamo di raggi X diffrazione (XRD), microscopia elettronica a scansione (SEM), eX-ray spettroscopia a dispersione di energia (EDS) per misurare la strutture cristalline, la morfologia e la composizione delle nanotrees ZnO / CdSSe (NTS). Il meccanismo di trasferimento proprietà ottiche e carica vettore tra i rami e le staminali sono state studiate per fotoluminescenza spettroscopia (PL) e le misure di durata PL risolte nel tempo.

<table><tbody><tr><td>ZnO</td><td>Sigma Aldrich</td><td>1314-13-2</td><td></td></tr><tr><td>Activated Carbon</td><td>Alfa</td><td>231-153-3</td><td></td></tr><tr><td>CdSe</td><td>Sigma Aldrich</td><td>1306-24-7</td><td></td></tr><tr><td>CdS</td><td>Sigma Aldrich</td><td>1306-23-6</td><td></td></tr><tr><td>Sapphire</td><td>MTI</td><td>2SP</td><td>a-plane, 10 &amp;times; 10 &amp;times; 1 mm</td></tr><tr><td>Furnace</td><td>Lindberg Blue M</td><td>SSP</td><td></td></tr><tr><td>Scanning electron microscope</td><td>Hitachi</td><td>S5700</td><td>assembled with an Oxford Inca X-act detector</td></tr><tr><td>X-ray powder diffractometer</td><td>Rigaku</td><td>MiniFlex</td><td>filtered Cu K&amp;alpha; radiation (&amp;lambda;=1.5418&amp;nbsp;&amp;Aring;)</td></tr><tr><td>Amplified Ti:sapphire oscillator</td><td>Coherent Mantis</td><td>Coherent Legend-Elite</td><td></td></tr><tr><td>Single photon detection module</td><td>ID Quantique</td><td>ID-100</td><td></td></tr><tr><td>Sputter coater</td><td>Cressington</td><td>308</td><td>assembled with gold target</td></tr><tr><td>Fiber probe spectrometer</td><td>Photon Control</td><td>SPM-002</td><td></td></tr><tr><td>Colored Glass Filter</td><td>Thorlabs</td><td>FGB37-A - &amp;Oslash;25 mm BG40</td><td>AR Coated: 350 - 700&amp;nbsp;nm</td></tr><tr><td>Compressed argon gas</td><td>Keen</td><td>7440-37-1</td><td></td></tr></tbody></table>

synthesis of hierarchical zno/cdsse heterostructure nanotrees

Una procedura di deposizione di vapore chimico in due fasi è qui impiegata per preparare ad albero gerarchico ZnO / CdSSe etero-nanostrutture. Le strutture sono costituite da rami CdSSe coltivati ​​su nanofili di ZnO che sono verticalmente allineate su un substrato di zaffiro trasparente. La morfologia è stata misurata mediante microscopia elettronica a scansione. La struttura cristallina è stata determinata mediante analisi ai raggi X diffrazione della polvere. Sia il ZnO gambo e rami CdSSe hanno una struttura cristallina prevalentemente wurtzite. Il rapporto molare tra S e Se nei rami CdSSe stata misurata mediante spettroscopia a raggi X a dispersione di energia. I rami CdSSe risultato in forte assorbimento della luce visibile. spettroscopia di fotoluminescenza (PL) ha mostrato che lo stelo e rami formano una eterogiunzione tipo II. misure a vita PL hanno mostrato una diminuzione della durata delle emissioni dagli alberi rispetto alle emissioni da ZnO singoli steli o rami CdSSe e indicare il trasferimento di carica veloce tra CdSSe e ZnO. il Verticamente allineato ZnO steli fornire una via diretta trasporto degli elettroni al substrato e di consentire una efficace separazione di carica dopo photoexcitation da luce visibile. La combinazione delle proprietà sopra menzionate rende ZnO / CdSSe nanotrees candidati promettenti per applicazioni in celle solari, fotocatalisi e dispositivi opto-elettronici.

La Figura 1 mostra il meccanismo di crescita di ZnO / CdSSe NT. La procedura coinvolto un processo catalitico di vapore-liquido-solido (VLS) seguito da un (VS) crescita non catalitico di vapore-solido. Nella prima fase VLS, ZnO e C reagiscono in atmosfera di Ar, con conseguente Zn metallico e ossido di carbonio. Zn viene successivamente disciolto in precursore oro sul substrato di zaffiro. nanofili di ZnO crescono dal Zn disciolto e ossigeno residuo. Nella seconda fase, ...

Watch this Scientific Journal Video about Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees at JoVE.com

Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

Qui, ci prepariamo e caratterizzare nuovi gerarchici nanostrutture di ZnO / CdSSe ad albero, in cui i rami CdSSe si coltivano su nanofili di ZnO allineati verticalmente. I nanotrees risultanti sono un materiale potenziale per la conversione dell&#39;energia solare e altri dispositivi opto-elettronici.

Sintesi di Hierarchical ZnO / CdSSe Heterostructure Nanotrees

A two-step chemical vapor deposition procedure is here employed to prepare tree-like hierarchical ZnO/CdSSe hetero-nanostructures. The structures are ...

synthesis-of-hierarchical-znocdsse-heterostructure-nanotrees

Research

JoVE Journal

Chemistry

9.9K Views.  University of Delaware.  Qui, ci prepariamo e caratterizzare nuovi gerarchici nanostrutture di ZnO / CdSSe ad albero, in cui i rami CdSSe si coltivano su nanofili di ZnO allineati verticalmente. I nanotrees risultanti sono un materiale potenziale per la conversione dell'energia solare e altri dispositivi opto-elettronici. 

Video: Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials offering a superior control over the spatial distribution of charge carriers across material interfaces. As this study demonstrates, a combination of donor-acceptor nanocrystal (NC) domains in a single nanoparticle can lead to the realization of efficient photocatalytic1-5 materials, while a layered assembly of donor- and acceptor-like nanocrystals films gives rise to photovoltaic materials.
Initially the paper focuses on the synthesis of composite inorganic nanocrystals, comprising linearly stacked ZnSe, CdS, and Pt domains, which jointly promote photoinduced charge separation. These structures are used in aqueous solutions for the photocatalysis of water under solar radiation, resulting in the production of H2 gas. To enhance the photoinduced separation of charges, a nanorod morphology with a linear gradient originating from an intrinsic electric field is used5. The inter-domain energetics are then optimized to drive photogenerated electrons toward the Pt catalytic site while expelling the holes to the surface of ZnSe domains for sacrificial regeneration (via methanol). Here we show that the only efficient way to produce hydrogen is to use electron-donating ligands to passivate the surface states by tuning the energy level alignment at the semiconductor-ligand interface. Stable and efficient reduction of water is allowed by these ligands due to the fact that they fill vacancies in the valence band of the semiconductor domain, preventing energetic holes from degrading it. Specifically, we show that the energy of the hole is transferred to the ligand moiety, leaving the semiconductor domain functional. This enables us to return the entire nanocrystal-ligand system to a functional state, when the ligands are degraded, by simply adding fresh ligands to the system4.
To promote a photovoltaic charge separation, we use a composite two-layer solid of PbS and TiO2 films. In this configuration, photoinduced electrons are injected into TiO2 and are subsequently picked up by an FTO electrode, while holes are channeled to a Au electrode via PbS layer6. To develop the latter we introduce a Semiconductor Matrix Encapsulated Nanocrystal Arrays (SMENA) strategy, which allows bonding PbS NCs into the surrounding matrix of CdS semiconductor. As a result, fabricated solids exhibit excellent thermal stability, attributed to the heteroepitaxial structure of nanocrystal-matrix interfaces, and show compelling light-harvesting performance in prototype solar cells7.

A general strategy for the development of charge-separating semiconductor nanocrystal composites deployable for solar energy production is presented. We show that assembly of donor-acceptor nanocrystal domains in a single nanoparticle geometry gives rise to a photocatalytic function, while bulk-heterojunctions of donor-acceptor nanocrystal films can be used for photovoltaic energy conversion.

Raccolta di energia solare per mezzo di separatori di carica-nanocristalli e loro Solidi

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials ...

Ricerca

Ingegneria

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using X-ray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach.

A protocol for the seeded synthesis of rod-shaped and tetrapod-shaped multicomponent nanostructures consisting of CdS and CdSe is presented.

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded ...

Chimica

Ultrahigh Density Array of Vertically Aligned Small-molecular Organic Nanowires on Arbitrary Substrates

In recent years &pi;-conjugated organic semiconductors have emerged as the active material in a number of diverse applications including large-area, low-cost displays, photovoltaics, printable and flexible electronics and organic spin valves. Organics allow (a) low-cost, low-temperature processing and (b) molecular-level design of electronic, optical and spin transport characteristics. Such features are not readily available for mainstream inorganic semiconductors, which have enabled organics to carve a niche in the silicon-dominated electronics market. The first generation of organic-based devices has focused on thin film geometries, grown by physical vapor deposition or solution processing. However, it has been realized that organic nanostructures can be used to enhance performance of above-mentioned applications and significant effort has been invested in exploring methods for organic nanostructure fabrication.	
A particularly interesting class of organic nanostructures is the one in which vertically oriented organic nanowires, nanorods or nanotubes are organized in a well-regimented, high-density array. Such structures are highly versatile and are ideal morphological architectures for various applications such as chemical sensors, split-dipole nanoantennas, photovoltaic devices with radially heterostructured "core-shell" nanowires, and memory devices with a cross-point geometry. Such architecture is generally realized by a template-directed approach. In the past this method has been used to grow metal and inorganic semiconductor nanowire arrays. More recently &pi;-conjugated polymer nanowires have been grown within nanoporous templates. However, these approaches have had limited success in growing nanowires of technologically important &pi;-conjugated small molecular weight organics, such as tris-8-hydroxyquinoline aluminum (Alq3), rubrene and methanofullerenes, which are commonly used in diverse areas including organic displays, photovoltaics, thin film transistors and spintronics.	
Recently we have been able to address the above-mentioned issue by employing a novel "centrifugation-assisted" approach. This method therefore broadens the spectrum of organic materials that can be patterned in a vertically ordered nanowire array. Due to the technological importance of Alq3, rubrene and methanofullerenes, our method can be used to explore how the nanostructuring of these materials affects the performance of aforementioned organic devices. The purpose of this article is to describe the technical details of the above-mentioned protocol, demonstrate how this process can be extended to grow small-molecular organic nanowires on arbitrary substrates and finally, to discuss the critical steps, limitations, possible modifications, trouble-shooting and future applications.

We report a simple method for fabricating an ultrahigh density array of vertically ordered small-molecular organic nanowires. This method allows for synthesis of complex heterostructured hybrid nanowire geometries, which can be inexpensively grown on arbitrary substrates. These structures have potential applications in organic electronics, optoelectronics, chemical sensing, photovoltaics and spintronics.

Altissima densità Array of allineato verticalmente Nanofili organici piccola molecolari su substrati arbitrarie

In  recent years &pi;-conjugated  organic semiconductors have emerged as the active material in a number of  diverse applications including large-area, ...

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

Modelli atomicamente definiti per epitassiale crescita di ossido Complex Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

Preparation of ZnO Nanorod/Graphene/ZnO Nanorod Epitaxial Double Heterostructure for Piezoelectrical Nanogenerator by Using Preheating Hydrothermal

Well-aligned ZnO nanostructures have been intensively studied over the last decade for remarkable physical properties and enormous applications. Here, we describe a one-step fabrication technique to synthesis freestanding ZnO nanorod/graphene/ZnO nanorod double heterostructure. The preparation of the double heterostructure is performed by using thermal chemical vapor deposition (CVD) and preheating hydrothermal technique. In addition, the morphological properties were characterized by using the scanning electron microscopy (SEM). The utility of freestanding double heterostructure is demonstrated by fabricating the piezoelectric nanogenerator. The electrical output is improved up to 200% compared to that of a single heterostructure owing to the coupling effect of the piezoelectricity between the arrays of ZnO nanorods on the top and bottom of graphene. This unique double heterostructure have a tremendous potential for applications of electrical and optoelectrical devices where the high number density and specific surface area of nanorod are needed, such as pressure sensor, immuno-biosensor and dye-sensitized solar cells.

One-step fabrication method for obtaining freestanding epitaxial double heterostructure is presented. This approach could achieve ZnO coverage with a higher number density than that of the epitaxial single heterostructure, leading to a piezoelectric nanogenerator with an increased output electrical performance.

Preparazione di ZnO Nanorod / grafene / ZnO Nanorod epitassiale Doppia Heterostructure per piezoelettrico nanogeneratore utilizzando preriscaldamento Idrotermale

Well-aligned ZnO nanostructures have been intensively studied over the last decade for remarkable physical properties and enormous applications. Here, we ...

Well-aligned Vertically Oriented ZnO Nanorod Arrays and their Application in Inverted Small Molecule Solar Cells

This manuscript describes how to design and fabricate efficient inverted solar cells, which are based on a two-dimensional conjugated small molecule (SMPV1) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), by utilizing ZnO nanorods (NRs) grown on a high quality Al-doped ZnO (AZO) seed layer. The inverted SMPV1:PC71BM solar cells with ZnO NRs that grew on both a sputtered and sol-gel processed AZO seed layer are fabricated. Compared with the AZO thin film prepared by the sol-gel method, the sputtered AZO thin film exhibits better crystallization and lower surface roughness, according to X-ray diffraction (XRD) and atomic force microscope (AFM) measurements. The orientation of the ZnO NRs grown on a sputtered AZO seed layer shows better vertical alignment, which is beneficial for the deposition of the subsequent active layer, forming better surface morphologies. Generally, the surface morphology of the active layer mainly dominates the fill factor (FF) of the devices. Consequently, the well-aligned ZnO NRs can be used to improve the carrier collection of the active layer and to increase the FF of the solar cells. Moreover, as an anti-reflection structure, it can also be utilized to enhance the light harvesting of the absorption layer, with the power conversion efficiency (PCE) of solar cells reaching 6.01%, higher than the sol-gel based solar cells with an efficiency of 4.74%.

This manuscript describes how to design and fabricate efficient inverted SMPV1:PC71BM solar cells with ZnO nanorods (NRs) grown on a high quality Al-doped ZnO (AZO) seed layer. The well-aligned vertically oriented ZnO NRs exhibit high crystalline properties. The power conversion efficiency of solar cells can reach 6.01%.

Ben allineati verticalmente orientato ZnO Nanorod matrici e la loro applicazione in invertito piccola molecola solare celle

This manuscript describes how to design and fabricate efficient inverted solar cells, which are based on a two-dimensional conjugated small molecule ...

A Standard and Reliable Method to Fabricate Two-Dimensional Nanoelectronics

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D materials is still in nascent stages, scientists cannot fully rely on traditional semiconductor techniques for related research. Delicate processes from locating the materials to electrode definition need to be well controlled. In this article, a universal fabrication protocol required in manufacturing nanoscale electronics, such as 2D quasi-heterojunction bipolar transistors (Q-HBT), and 2D back-gated transistors are demonstrated. This protocol includes the determination of material position, electron beam lithography (EBL), metal electrode definition, et al. A step by step narrative of the fabrication procedures for these devices are also presented. Furthermore, results show that each of the fabricated devices has achieved high performance with high repeatability. This work reveals a comprehensive description of process flow for preparing 2D nano-electronics, enables the research groups to access this information, and pave the way toward future electronics.

The article aims to introduce a standard and reliable fabrication procedure for the development of future low dimensional nanoelectronics.

Un metodo Standard e affidabile per fabbricare nanoelettronica bidimensionale

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D ...

Fabrication of Schottky Diodes on Zn-polar BeMgZnO/ZnO Heterostructure Grown by Plasma-assisted Molecular Beam Epitaxy

Heterostructure field effect transistors (HFETs) utilizing a two dimensional electron gas (2DEG) channel have a great potential for high speed device applications. Zinc oxide (ZnO), a semiconductor with a wide bandgap (3.4 eV) and high electron saturation velocity has gained a great deal of attention as an attractive material for high speed devices. Efficient gate modulation, however, requires high-quality Schottky contacts on the barrier layer. In this article, we present our Schottky diode fabrication procedure on Zn-polar BeMgZnO/ZnO heterostructure with high density 2DEG which is achieved through strain modulation and incorporation of a few percent Be into the MgZnO-based barrier during growth by molecular beam epitaxy (MBE). To achieve high crystalline quality, nearly lattice-matched high-resistivity GaN templates grown by metal-organic chemical vapor deposition (MOCVD) are used as the substrate for the subsequent MBE growth of the oxide layers. To obtain the requisite Zn-polarity, careful surface treatment of GaN templates and control over the VI/II ratio during the growth of low temperature ZnO nucleation layer are utilized. Ti/Au electrodes serve as Ohmic contacts, and Ag electrodes deposited on the O2 plasma pretreated BeMgZnO surface are used for Schottky contacts.

Attainment of high-quality Schottky contacts is imperative for achieving efficient gate modulation in heterostructure field effect transistors (HFETs). We present the fabrication methodology and characteristics of Schottky diodes on Zn-polar BeMgZnO/ZnO heterostructures with high-density two dimensional electron gas (2DEG), grown by plasma-assisted molecular beam epitaxy on GaN templates.

Fabbricazione di diodi Schottky su Zn-polar eterostruttura BeMgZnO/ZnO cresciuto di epitassia da fasci molecolari assistita da Plasma

Heterostructure field effect transistors (HFETs) utilizing a two dimensional electron gas (2DEG) channel have a great potential for high speed device ...

Growth of Gold Dendritic Nanoforests on Titanium Nitride-coated Silicon Substrates

In this study, a high-power impulse magnetron sputtering system is used to coat a flat and firm titanium nitride (TiN) film on silicon (Si) wafers, and a fluoride-assisted galvanic replacement reaction (FAGRR) is employed for the rapid and easy deposition of gold dendritic nanoforests (Au DNFs) on the TiN/Si substrates. Scanning electron microscopy (SEM) images and energy-dispersive X-ray spectroscopy patterns of TiN/Si and Au DNFs/TiN/Si samples validate that the synthesis process is accurately controlled. Under the reaction conditions in this study, the thickness of the Au DNFs increases linearly to 5.10 &#177; 0.20 &#181;m within 15 min of the reaction. Therefore, the employed synthesis procedure is a simple and rapid approach for preparing Au DNFs/TiN/Si composites.

This study presents a feasible procedure for synthesizing gold dendritic nanoforests on titanium nitride/silicon substrates. The thickness of gold dendritic nanoforests increases linearly within 15 min of a synthesis reaction.

Crescita di Nanoforests dendritiche oro su substrati di silicio rivestiti in nitruro di titanio

In this study, a high-power impulse magnetron sputtering system is used to coat a flat and firm titanium nitride (TiN) film on silicon (Si) wafers, and a ...

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations

Computational tools based on density-functional theory (DFT) enable the exploration of the qualitatively new, experimentally attainable nanoscale compounds for a targeted application. Theoretical simulations provide a profound understanding of the intrinsic electronic properties of functional materials. The goal of this protocol is to search for photocatalyst candidates by computational dissection. Photocatalytic applications require suitable band gaps, appropriate band edge positions relative to the redox potentials. Hybrid functionals can provide accurate values of these properties but are computationally expensive, whereas the results at the Perdew-Burke-Ernzerhof (PBE) functional level could be effective for suggesting strategies for band structure engineering via electric field and tensile strain aiming to enhance the photocatalytic performance. To illustrate this, in the present manuscript, the DFT based simulation tool VASP is used to investigate the band alignment of nanocomposites in combinations of nanotubes and nanoribbons in the ground state. To address the lifetime of photogenerated holes and electrons in the excited state, nonadiabatic dynamics calculations are needed.

Calculations performed by the Vienna Ab initio Simulation Package can be used to identify the intrinsic electronic properties of nanoscale materials and predict the potential water-splitting photocatalysts.