Name: preparation of macroporous epitaxial quartz films on silicon by chemical solution deposition
Uploaded: 2015-12-21T15:00:00
Description: Watch this Scientific Journal Video about Preparation of Macroporous Epitaxial Quartz Films on Silicon by Chemical Solution Deposition at JoVE.com

This work was partially funded by a PEPS project of Cellule Energie INSIS-CNRS (1D-RENOX) to ACG and the Spanish Government (MAT2012-35324 and PIE-201460I004).

1. Preparation of the Sol
<ol>
	<li>Prepare a solution of prehydrolyzed tetraethyl orthosilicate (TEOS) the day before the preparation of the gel films in a fume hood in which a lab balance and a magnetic stirrer are placed. In this step and throughout the protocol wear a lab coat, gloves and safety goggles.
	<ol>
		<li>In a 50 ml beaker containing a Teflon coated magnetic stirring bar weigh 1.68 g of CTAB, add 48.13 ml of ethanol and 3.00 ml of HCl 35%, cover the beaker with a watch glass and stir until the CTAB is co...

<ol>
	<li>Esser, A. T., Smith, K. C., Gowrishankar, T. R., Vasilkoski, Z., Weaver, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+for+the+intracellular+manipulation+of+organelles+by+conventional+electroportation.">Mechanisms for the intracellular manipulation of organelles by conventional electroportation.</a> Biophys. J. 98 (11), 2506-2514 (2010).</li><li>Stava, E., Yu, M., Shin, H. C., Shin, H., Kreft, D. J., Blick, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+fabrication+and+piezoelectric+tuning+of+micro-+and+nanopores+in+single+crystal+quartz.">Rapid fabrication and piezoelectric tuning of micro- and nanopores in single crystal quartz.</a> Lab Chip. 13 (1), 156-160 (2013).</li><li>Varshneya, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Fundamentals of Inorganic Glasses. , (1994).</li><li>Christov, M., Kirov, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ratio+of+dissolving+surface+area/growing+surface+area+in+the+hydrothermal+growth+of+quartz.">The ratio of dissolving surface area/growing surface area in the hydrothermal growth of quartz.</a> J. Cryst. Growth. 131 (3-4), 560-564 (1993).</li><li>Bertone, J. F., Cizeron, J., Wahi, R. K., Bosworth, J. K., Colvin, V. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrothermal+synthesis+of+quartz+nanocrystals.">Hydrothermal synthesis of quartz nanocrystals.</a> Nano Lett. 3, 655-659 (2003).</li><li>Jiang, Y., Brinker, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrothermal+synthesis+of+monodisperse+single-crystalline+alpha-quartz+nanospheres.">Hydrothermal synthesis of monodisperse single-crystalline alpha-quartz nanospheres.</a> Chem. Comm. 47 (26), 7524-7526 (2011).</li><li>Okabayashi, M., Miyazaki, K., Kono, T., Tanaka, M., Toda, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+Spherical+Particles+with+Quartz+Single.">Preparation of Spherical Particles with Quartz Single.</a> Chem. Lett. 34 (1), 58-59 (2005).</li><li>Carretero-Genevrier, A., 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=Soft-Chemistry-Based+Routes+to+Epitaxial+&#945;-Quartz+Thin+Films+with+Tunable+Textures.">Soft-Chemistry-Based Routes to Epitaxial &#945;-Quartz Thin Films with Tunable Textures.</a> Science. 340 (6134), 827-831 (2013).</li><li>Brinker, C. J., Clem, P. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quartz+on+Silicon.">Quartz on Silicon.</a> Science. 340 (6134), 818-819 (2013).</li><li>Brinker, C. J., Lu, Y., Sellinger, A., Fan, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaporation-Induced+Self-Assembly:+Nanostructures+Made+Easy.">Evaporation-Induced Self-Assembly: Nanostructures Made Easy.</a> Adv. Mater. 11 (7), 579-585 (1999).</li><li>Griffith, C. S., Sizgek, G. D., Sizgek, E., Scales, N., Yee, P. J., Luca, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesoporous+Zirconium+Titanium+Oxides.+Part+1:+Porosity+Modulation+and+Adsorption+Properties+of+Xerogels.">Mesoporous Zirconium Titanium Oxides. Part 1: Porosity Modulation and Adsorption Properties of Xerogels.</a> Langmuir. 24 (21), 12312-12322 (2008).</li><li>Lu, Y., 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=Continuous+formation+of+supported+cubic+and+hexagonal+mesoporous+films+by+sol-gel+dip-coating.">Continuous formation of supported cubic and hexagonal mesoporous films by sol-gel dip-coating.</a> Nature. 389 (6649), 364-368 (1997).</li><li>Drisko, G. L., 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=Water-Induced+Phase+Separation+Forming+Macrostructured+Epitaxial+Quartz+Films+on+Silicon.">Water-Induced Phase Separation Forming Macrostructured Epitaxial Quartz Films on Silicon.</a> Adv. Funct. Mater. 24 (35), 5494-5502 (2014).</li></ol>

The presented method is a bottom-up approach to produce macroporous quartz films on Si. Compared to the standard method of production of quartz films, a top down technology based on cutting and polishing of large hydrothermally grown crystals, the method described in the protocol allows obtaining much thinner films with thicknesses between 150 and 450 nm which can be controlled with the withdrawal rate. All experimental details regarding the control of quartz films thickness, and piezoelectric response are reported in re...

When a piezoelectric material like &#945;-quartz is submitted to a voltage bias it undergoes a mechanical deformation. If this material is porous, these volume changes can lead to pore expansion or contraction, creating a responsive system similar to what may be observed in living biological organelles.1 Deformable porous &#945;-quartz has been produced using microfabrication,2 but such techniques cannot yet produce 3-D pore structures, and pore diameters are on the order of hundreds of nanometers. Crystallization of structured amorphous silica has been hindered by inhomogeneous nucleation caused by high surface energies and architectural deformation due to coarsening and melting. Moreover, since all forms of silica are built upon extremely stable SiO4 tetrahedral networks, the free energies of formation of amorphous silica, &#945;-quartz and other SiO2 polymorphs are nearly equal in a wide range of temperatures, making it difficult to produce &#945;-quartz as a single polymorph from the crystallization of an amorphous silica gel.3 Another aspect that makes harder the controlled crystallization of structured amorphous silica is that quartz presents a relatively slow nucleation rate but an extremely fast growth rate, reported between 10-94 nm/sec.4,5 Slow nucleation coupled with fast growth tends to generate crystals much larger than the original nanoporous structure, thus the original morphology is lost. Alkali metals, such as Na+ and Li+, have been used to crystallize &#945;-quartz, frequently in combination with hydrothermal treatment.5,6 Also, a Ti4+/Ca2+ combination was employed to crystallize spherical particles of silica into quartz by a soft chemistry route using silicon alcoxides.7 However, the controlled crystallization of a structured amorphous silica film into quartz remained a challenge.
Recently, strontium has been found to catalyze the nucleation and growth of crystalline SiO2 under ambient pressure and relatively low temperatures.8,9 Epitaxy, arises from the favorable mismatch between &#945;-quartz and the &#60;100&#62; silicon substrate, producing oriented piezoelectric thin films. Evaporation-induced self-assembly to produce mesoporous silica films has been used since 1999.10 This technique has been studied and applied to a multitude of templating agents under various conditions to produce pores of variable sizes and mesophases. It has been found that subnanometric changes in mesopore size can have a dramatic effect on solute diffusion through porous systems11, validating this extensive attention to pore structure. Moreover, accessibility to the internal silica pore system can be obtained by controlling the micellar phase of the template.12
Here, the synthesis route that allows unprecedented control over the thickness and pore size of amorphous silica layers using a novel phase separation is demonstrated.13 These films are infiltrated with Sr(II) salts and crystallized to &#945;-quartz at 1,000 &#176;C under air at ambient pressure. The pore size retainable using this crystallization process is determined, and the effect of wall thickness and film thickness is studied. Finally the piezoelectricity and the deformability of the pore system are studied.

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:180px;">Dip coater</td>
			<td style="width:281px;">Nadetech&#160;</td>
			<td style="width:173px;">ND-DC 11/150&#160;</td>
			<td style="width:80px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:180px;">Furnace</td>
			<td style="width:281px;">Nabertherm&#160;</td>
			<td>R 50/250/12</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:180px;">Atomic Force Microscope</td>
			<td style="width:281px;">Agilent&#160;</td>
			<td>5500 LS</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:180px;">Materials and Reagents&#160;</td>
			<td style="width:281px;"></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:180px;">Silicon wafers</td>
			<td style="width:281px;">SHE Europe Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:180px;">SrCl2&#183;6H2O</td>
			<td style="width:281px;">Aldrich</td>
			<td>13909</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:180px;">CTAB</td>
			<td style="width:281px;">Aldrich</td>
			<td>H5582</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:180px;">Ethanol Absolute&#160;</td>
			<td style="width:281px;">Aldrich</td>
			<td>161086</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:180px;">HCl 35% solution</td>
			<td style="width:281px;">PanReac</td>
			<td>721019</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:180px;">TEOS</td>
			<td style="width:281px;">Aldrich</td>
			<td>131903</td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation of macroporous epitaxial quartz films on silicon by chemical solution deposition

This work describes the detailed protocol for preparing piezoelectric macroporous epitaxial quartz films on silicon(100) substrates. This is a three-step process based on the preparation of a sol in a one-pot synthesis which is followed by the deposition of a gel film on Si(100) substrates by evaporation induced self-assembly using the dip-coating technique and ends with a thermal treatment of the material to induce the gel crystallization and the growth of the quartz film. The formation of a silica gel is based on the reaction of a tetraethyl orthosilicate and water, catalyzed by HCl, in ethanol. However, the solution contains two additional components that are essential for preparing mesoporous epitaxial quartz films from these silica gels dip-coated on Si. Alkaline earth ions, like Sr2+ act as glass melting agents that facilitate the crystallization of silica and in combination with cetyl trimethylammonium bromide (CTAB) amphiphilic template form a phase separation responsible of the macroporosity of the films. The good matching between the quartz and silicon cell parameters is also essential in the stabilization of quartz over other SiO2 polymorphs and is at the origin of the epitaxial growth.

The progress of the material synthesis was controlled by monitoring different aspects. After the dip-coating process one can observe the aspect of the films, the eventual appearance of diffraction structures in the reflected spot of a green laser and the Scanning Electron Microscopy (SEM) images in backscattered electrons mode (Figure 1A-B). After the crystallization process it is important to record Atomic Force Microscopy (AFM) topographic images (Figure 1C</str...

Watch this Scientific Journal Video about Preparation of Macroporous Epitaxial Quartz Films on Silicon by Chemical Solution Deposition at JoVE.com

Preparation of Macroporous Epitaxial Quartz Films on Silicon by Chemical Solution Deposition

A protocol is presented for the preparation of piezoelectric macroporous epitaxial films of quartz on silicon by solution chemistry using dip-coating and thermal treatments in air.

This work describes the detailed protocol for preparing piezoelectric macroporous epitaxial quartz films on silicon(100) substrates. This is a three-step ...

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Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m2/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.

Herein the procedures for plasma enhanced chemical vapor deposition of perfluoroalkanes on microporous materials such as metal-organic frameworks to enhance their stability and hydrophobicity are described. Furthermore, breakthrough testing of milligram quantities of samples is described in detail.

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high ...

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.

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

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene

Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in traditional materials, including low cost and mechanical flexibility. In a similar vein, it would be advantageous to expand the use of organics into high frequency electronics and spin-based electronics. This work presents a synthetic process for the growth of thin films of the room temperature organic ferrimagnet, vanadium tetracyanoethylene (V[TCNE]x, x~2) by low temperature chemical vapor deposition (CVD). The thin film is grown at &#60;60 &#176;C, and can accommodate a wide variety of substrates including, but not limited to, silicon, glass, Teflon and flexible substrates. The conformal deposition is conducive to pre-patterned and three-dimensional structures as well. Additionally this technique can yield films with thicknesses ranging from 30 nm to several microns. Recent progress in optimization of film growth creates a film whose qualities, such as higher Curie temperature (600 K), improved magnetic homogeneity, and narrow ferromagnetic resonance line-width (1.5 G) show promise for a variety of applications in spintronics and microwave electronics.

We present the synthesis of the organic-based ferrimagnet vanadium tetracyanoethylene (V[TCNE]x, x~2) via low temperature chemical vapor deposition (CVD). This optimized recipe yields an increase in Curie temperature from 400 K to over 600 K and a dramatic improvement in magnetic resonance properties.

Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in ...

Preparation of Highly Porous Coordination Polymer Coatings on Macroporous Polymer Monoliths for Enhanced Enrichment of Phosphopeptides

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous polymer monoliths. The developed approach is based on the preparation of a macroporous polymer containing carboxylic acid functional groups and the subsequent step-by-step solution-based controlled growth of a layer of a porous coordination polymer on the surface of the pores of the polymer monolith. The prepared metal-organic polymer hybrid has a high specific micropore surface area. The amount of iron(III) sites is enhanced through metal-organic coordination on the surface of the pores of the functional polymer support. The increase of metal sites is related to the number of iterations of the coating process.
The developed preparation scheme is easily adapted to a capillary column format. The functional porous polymer is prepared as a self-contained single-block porous monolith within the capillary, yielding a flow-through separation device with excellent flow permeability and modest back-pressure. The metal-organic polymer hybrid column showed excellent performance for the enrichment of phosphopeptides from digested proteins and their subsequent detection using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The presented experimental protocol is highly versatile, and can be easily implemented to different organic polymer supports and coatings with a plethora of porous coordination polymers and metal-organic frameworks for multiple purification and/or separation applications.

A procedure for the preparation of porous hybrid separation media composed of a macroporous polymer monolith internally coated by a high surface area microporous coordination polymer is presented.

We describe a protocol for the preparation of hybrid materials based on highly porous coordination polymer coatings on the internal surface of macroporous ...

Preparation of Mica and Silicon Substrates for DNA Origami Analysis and Experimentation

The designed nature and controlled, one-pot synthesis of DNA origami provides exciting opportunities in many fields, particularly nanoelectronics. Many of these applications require interaction with and adhesion of DNA nanostructures to a substrate. Due to its atomically flat and easily cleaned nature, mica has been the substrate of choice for DNA origami experiments. However, the practical applications of mica are relatively limited compared to those of semiconductor substrates. For this reason, a straightforward, stable, and repeatable process for DNA origami adhesion on derivatized silicon oxide is presented here. To promote the adhesion of DNA nanostructures to silicon oxide surface, a self-assembled monolayer of 3-aminopropyltriethoxysilane (APTES) is deposited from an aqueous solution that is compatible with many photoresists. The substrate must be cleaned of all organic and metal contaminants using Radio Corporation of America (RCA) cleaning processes and the native oxide layer must be etched to ensure a flat, functionalizable surface. Cleanrooms are equipped with facilities for silicon cleaning, however many components of DNA origami buffers and solutions are often not allowed in them due to contamination concerns. This manuscript describes the set-up and protocol for in-lab, small-scale silicon cleaning for researchers who do not have access to a cleanroom or would like to incorporate processes that could cause contamination of a cleanroom CMOS clean bench. Additionally, variables for regulating coverage are discussed and how to recognize and avoid common sample preparation problems is described.

Reproducible cleaning processes for substrates used in DNA origami research are described, including bench-top RCA cleaning and derivatization of silicon oxide. Protocols for surface preparation, DNA origami deposition, drying parameters, and simple experimental set-ups are illustrated.

The designed nature and controlled, one-pot synthesis of DNA origami provides exciting opportunities in many fields, particularly nanoelectronics. Many of ...

Epitaxial Growth of Perovskite Strontium Titanate on Germanium via Atomic Layer Deposition

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and conformality by taking advantage of self-limiting reactions between vapor-phase precursors and the growing film. Perovskite oxides present potential for next-generation electronic materials, but to-date have mostly been deposited by physical methods. This work outlines a method for depositing SrTiO3 (STO) on germanium using ALD. Germanium has higher carrier mobilities than silicon and therefore offers an alternative semiconductor material with faster device operation. This method takes advantage of the instability of germanium's native oxide by using thermal deoxidation to clean and reconstruct the Ge (001) surface to the 2&#215;1 structure. 2-nm thick, amorphous STO is then deposited by ALD. The STO film is annealed under ultra-high vacuum and crystallizes on the reconstructed Ge surface. Reflection high-energy electron diffraction (RHEED) is used during this annealing step to monitor the STO crystallization. The thin, crystalline layer of STO acts as a template for subsequent growth of STO that is crystalline as-grown, as confirmed by RHEED. In situ X-ray photoelectron spectroscopy is used to verify film stoichiometry before and after the annealing step, as well as after subsequent STO growth. This procedure provides framework for additional perovskite oxides to be deposited on semiconductors via chemical methods in addition to the integration of more sophisticated heterostructures already achievable by physical methods.

This work details the procedures for the growth and characterization of crystalline SrTiO3 directly on germanium substrates by atomic layer deposition. The procedure illustrates the ability of an all-chemical growth method to integrate oxides monolithically onto semiconductors for metal-oxide semiconductor devices.

Atomic layer deposition (ALD) is a commercially utilized deposition method for electronic materials. ALD growth of thin films offers thickness control and ...

Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, we present a protocol for the fabrication of this material via the low-pressure vapor assisted solution process (LP-VASP) method, which yields ~19% power conversion efficiency in planar heterojunction perovskite solar cells. First, we report the synthesis of methylammonium iodide (CH3NH3I) and methylammonium bromide (CH3NH3Br) from methylamine and the corresponding halide acid (HI or HBr). Then, we describe the fabrication of pinhole-free, continuous methylammonium-lead halide perovskite (CH3NH3PbX3 with X = I, Br, Cl and their mixture) films with the LP-VASP. This process is based on two steps: i) spin-coating of a homogenous layer of lead halide precursor onto a substrate, and ii) conversion of this layer to CH3NH3PbI3-xBrx by exposing the substrate to vapors of a mixture of CH3NH3I and CH3NH3Br at reduced pressure and 120 &#176;C. Through slow diffusion of the methylammonium halide vapor into the lead halide precursor, we achieve slow and controlled growth of a continuous, pinhole-free perovskite film. The LP-VASP allows synthetic access to the full halide composition space in CH3NH3PbI3-xBrx with 0&#160;&#8804; x&#160;&#8804; 3. Depending on the composition of the vapor phase, the bandgap can be tuned between 1.6 eV&#160;&#8804; Eg&#160;&#8804; 2.3 eV. In addition, by varying the composition of the halide precursor and of the vapor phase, we can also obtain CH3NH3PbI3-xClx. Films obtained from the LP-VASP are reproducible, phase pure as confirmed by X-ray diffraction measurements, and show high photoluminescence quantum yield. The process does not require the use of a glovebox.

Here, we present a protocol for the synthesis of CH3NH3I and CH3NH3Br precursors and the subsequent formation of pinhole-free, continuous CH3NH3PbI3-xBrx thin films for the application in high efficiency solar cells and other optoelectronic devices.

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, ...

Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, their high cost production and/or incompatibility with microfabrication technologies, due to the use of pre-deposited catalyst-seeds and/or high processing temperatures exceeding 900 &#176;C, represent a drawback for a widespread use of these methods. Here, however, we report the synthesis of ZnO rods via a non-catalyzed vapor-solid mechanism enabled by using an aerosol-assisted chemical vapor deposition (CVD) method at 400 &#176;C with zinc chloride (ZnCl2) as the precursor and ethanol as the carrier solvent. This method provides both single-step formation of ZnO rods and the possibility of their direct integration with various substrate types, including silicon, silicon-based micromachined platforms, quartz, or high heat resistant polymers. This potentially facilitates the use of this method at a large-scale, due to its compatibility with state-of-the-art microfabrication processes for device manufacture. This report also describes the properties of these structures (e.g., morphology, crystalline phase, optical band gap, chemical composition, electrical resistance) and validates its gas sensing functionality towards carbon monoxide.

Columnar zinc oxide structures in the form of rods are synthesized via aerosol-assisted chemical vapor deposition without the use of pre-deposited catalyst-seed particles. This method is scalable and compatible with various substrates based on either silicon, quartz or polymers.

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, ...

Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. Conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and a semiconducting polymer, poly(thieno[3,2-b]thiophene) (PTT), were deposited on unconventional highly-disordered and textured substrates with high surface areas, such as paper, towels and fabrics. This reported deposition chamber is an improvement of previous vapor reactors because our system can accommodate both volatile and nonvolatile monomers, such as 3,4-propylenedioxythiophene and thieno[3,2-b]thiophene. Utilization of both solid and liquid oxidants are also demonstrated. One limitation of this method is that it lacks sophisticated in situ thickness monitors. Polymer coatings made by the commonly used solution-based coating methods, such as spin-coating and surface grafting, are often not uniform or susceptible to mechanical degradation. This reported vapor phase deposition method overcomes those drawbacks and is a strong alternative to common solution-based coating methods. Notably, polymer films coated by the reported method are uniform and conformal on rough surfaces, even at a micrometer scale. This feature allows for future application of vapor deposited polymers in electronics devices on flexible and highly textured substrates.

This paper presents a protocol for reactive vapor deposition of poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), and poly(thieno[3,2-b]thiophene) films on glass slides and rough substrates, such as textiles and paper.

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. ...

Deposition of Porous Sorbents on Fabric Supports

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material that can be subsequently treated by dip coating. Dip coating with a sol preparation provides a supported porous layer on the fabric. In this case, the porous layer is a porphyrin functionalized sorbent system based on a powdered material that has been demonstrated previously for the capture and conversion of phosgene. A representative coating is applied to cotton fabric at a loading level of 10 mg/g. This coating has minimal impact on water vapor transport through the fabric (93% of the support fabric rate) while significantly reducing transport of 2-chloroethyl ethyl sulfide (CEES) through the material (7% of support fabric rate). The described approaches are suitable for use with other fabrics providing amine and hydroxyl groups for modification and can be used in combination with other sol preparations to produce varying functionality.

This report details a microwave-initiated approach for deposition of porphyrin functionalized porous organosilicate sorbents on a cotton fabric and demonstrates reduction in 2-chloroethyl ethyl sulfide (CEES) transport through the fabric resulting from this treatment.

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material ...