This work was supported by the Ministry of Science and Technology, Taiwan, under contract numbers MOST 105-2221-E-492-003-MY2 and MOST 107-2622-E-239-002-CC3.

1.&#160;Sample preparation
<ol>
	<li>TiN substrate preparation using a high-power impulse magnetron sputtering system
	<ol>
		<li>Cut a 4 inch n-type silicon wafer into 2 cm x 2 cm samples.</li>
		<li>Wash the samples using acetone, isopropanol, and deionized water.</li>
		<li>Dry them using an N2 spray for 5 min.</li>
		<li>Place the washed Si samples in a sample holder and place the sample holder into a high-power impulse magnetron sputtering (HiPIMS) chamber.</li>
		<li>Place a titanium target with a diameter of 4 inches on a sputtering cathode.</li>
		<li>Reduce the chamber pressure to less than 8 x 10-6 Torr by using a mechanical pump and cryopump.</li>
		<li>Use HiPIMS to deposit a Ti layer on a silicon wafer and deposit a TiN layer on the Ti layer. See Table 1 for the deposition parameters of Ti and TiN layers in HiPIMS.</li>
	</ol>
	</li>
	<li>Au DNF preparation on TiN/Si substrates
	<ol>
		<li>Place 24 mL of a reactant solution comprising 10 mM chloroauric acid (HAuCl4) and buffered oxide etchant solution comprising 11.4% NH4F and 2.3% HF into a Teflon container measuring 5 cm x 5 cm x 5 cm.</li>
		<li>Dip the substrates into the mixture solution for 3 min.</li>
		<li>Remove the sample and wash it using deionized water.</li>
		<li>Dry the sample using the N2 spray and then incubate it at 120 &#176;C for 5 min to obtain Au DNFs/TiN/Si samples.</li>
		<li>Repeat the Au DNF preparation 10x.</li>
	</ol>
	</li>
</ol>
2.&#160;Sample examination
<ol>
	<li>Scanning electron microscopy analyses
	<ol>
		<li>Cut the sample into 0.4 cm x 0.8 cm with a tungsten pen, and clean it using the N2 spray.</li>
		<li>Coat a thin Pt film on the sample by an ion sputter coater for 50 s.</li>
		<li>Place the prepared sample into a scanning electron microscopy (SEM) instrument.</li>
		<li>Obtain SEM images by the scanning electron microscope and conduct element analysis21,22.</li>
	</ol>
	</li>
	<li>X-ray diffraction analyses
	<ol>
		<li>Place the sample into an X-ray diffraction (XRD) instrument.</li>
		<li>Obtain XRD patterns21,22.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Nehl, C. L., Hafner, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shape-dependent+plasmon+resonances+of+gold+nanoparticles.">Shape-dependent plasmon resonances of gold nanoparticles.</a> Journal of Materials Chemistry. 18 (21), 2415-2419 (2008).</li><li>Augui&#233;, B., Barnes, W. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collective+resonances+in+gold+nanoparticle+arrays.">Collective resonances in gold nanoparticle arrays.</a> Physical Review Letters. 101 (14), 143902 (2008).</li><li>Sakai, N., Fujiwara, Y., Arai, M., Yu, K., Tatsuma, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrodeposition+of+gold+nanoparticles+on+ITO:+Control+of+morphology+and+plasmon+resonance-based+absorption+and+scattering.">Electrodeposition of gold nanoparticles on ITO: Control of morphology and plasmon resonance-based absorption and scattering.</a> Journal of Electroanalytical Chemistry. 628 (1-2), 7-15 (2009).</li><li>Shiao, M. H., Lai, C. P., Liao, B. H., Lin, Y. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+photoillumination+on+gold-nanoparticle-assisted+chemical+etching+of+silicon.">Effect of photoillumination on gold-nanoparticle-assisted chemical etching of silicon.</a> Journal of Nanomaterials. 2018, 5479605 (2018).</li><li>Ayati, 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=Photocatalytic+degradation+of+nitrobenzene+by+gold+nanoparticles+decorated+polyoxometalate+immobilized+TiO2+nanotubes.">Photocatalytic degradation of nitrobenzene by gold nanoparticles decorated polyoxometalate immobilized TiO2 nanotubes.</a> Separation and Purification Technology. 171, 62-68 (2016).</li><li>Huang, T., Meng, F., Qi, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+synthesis+of+dendritic+gold+nanostructures+assisted+by+supramolecular+complexes+of+surfactant+with+cyclodextrin.">Controlled synthesis of dendritic gold nanostructures assisted by supramolecular complexes of surfactant with cyclodextrin.</a> Langmuir. 26 (10), 7582-7589 (2009).</li><li>Lahiri, A., Wen, R., Kuimalee, S., Kobayashi, S. I., Park, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-step+growth+of+needle+and+dendritic+gold+nanostructures+on+silicon+for+surface+enhanced+Raman+scattering.">One-step growth of needle and dendritic gold nanostructures on silicon for surface enhanced Raman scattering.</a> CrystEngComm. 14 (4), 1241-1246 (2012).</li><li>Lahiri, A., Wen, R., Kobayashi, S. I., Wang, P., Fang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unique+and+unusual+pattern+demonstrating+the+crystal+growth+through+bubble+formation.">Unique and unusual pattern demonstrating the crystal growth through bubble formation.</a> Crystal Growth &#38; Design. 12 (3), 1666-1670 (2012).</li><li>Lahiri, 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=Photo-assisted+control+of+gold+and+silver+nanostructures+on+silicon+and+its+SERRS+effect.">Photo-assisted control of gold and silver nanostructures on silicon and its SERRS effect.</a> Journal of Physics D: Applied Physics. 46 (27), 275303 (2013).</li><li>Lv, Z. 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=Facile+and+controlled+electrochemical+route+to+three-dimensional+hierarchical+dendritic+gold+nanostructures.">Facile and controlled electrochemical route to three-dimensional hierarchical dendritic gold nanostructures.</a> Electrochimica Acta. 109, 136-144 (2013).</li><li>Dutta, 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=Mesoporous+gold+and+palladium+nanoleaves+from+liquid&#8211;liquid+interface:+enhanced+catalytic+activity+of+the+palladium+analogue+toward+hydrazine-assisted+room-temperature+4-nitrophenol+reduction.">Mesoporous gold and palladium nanoleaves from liquid&#8211;liquid interface: enhanced catalytic activity of the palladium analogue toward hydrazine-assisted room-temperature 4-nitrophenol reduction.</a> ACS Applied Materials &#38; Interfaces. 6 (12), 9134-9143 (2014).</li><li>Lin, C. T., 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=Rapid+fabrication+of+three-dimensional+gold+dendritic+nanoforests+for+visible+light-enhanced+methanol+oxidation.">Rapid fabrication of three-dimensional gold dendritic nanoforests for visible light-enhanced methanol oxidation.</a> Electrochimica Acta. 192, 15-21 (2016).</li><li>Lahiri, A., Kobayashi, S. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electroless+deposition+of+gold+on+silicon+and+its+potential+applications.">Electroless deposition of gold on silicon and its potential applications.</a> Surface Engineering. 32 (5), 321-337 (2016).</li><li>White, N., 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=Surface/interface+analysis+and+optical+properties+of+RF+sputter-deposited+nanocrystalline+titanium+nitride+thin+films.">Surface/interface analysis and optical properties of RF sputter-deposited nanocrystalline titanium nitride thin films.</a> Applied Surface Science. 292, 74-85 (2014).</li><li>Zhao, J., 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=Surface+enhanced+Raman+scattering+substrates+based+on+titanium+nitride+nanorods.">Surface enhanced Raman scattering substrates based on titanium nitride nanorods.</a> Optical Materials. 47, 219-224 (2015).</li><li>Lorite, I., Serrano, A., Schwartzberg, A., Bueno, J., Costa-Kr&#228;mer, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+enhanced+Raman+spectroscopy+by+titanium+nitride+non-continuous+thin+films.">Surface enhanced Raman spectroscopy by titanium nitride non-continuous thin films.</a> Thin Solid Films. 531, 144-146 (2013).</li><li>O&#8217;Kelly, J. 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=Room+temperature+electroless+plating+copper+seed+layer+process+for+damascene+interlevel+metal+structures.">Room temperature electroless plating copper seed layer process for damascene interlevel metal structures.</a> Microelectronic Engineering. 50 (1), 473-479 (2000).</li><li>Cesiulis, H., Ziomek-Moroz, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrocrystallization+and+electrodeposition+of+silver+on+titanium+nitride.">Electrocrystallization and electrodeposition of silver on titanium nitride.</a> Journal of Applied Electrochemistry. 30 (11), 1261-1268 (2000).</li><li>Wu, Y., Chen, W. C., Fong, H. P., Wan, C. C., Wang, Y. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Displacement+reactions+between+metal+ions+and+nitride+barrier+layer/silicon+substrate.">Displacement reactions between metal ions and nitride barrier layer/silicon substrate.</a> Journal of the Electrochemical Society. 149 (5), G309-G317 (2002).</li><li>Koo, H. C., Ahn, E. J., Kim, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct-electroplating+of+Ag+on+pretreated+TiN+surfaces.">Direct-electroplating of Ag on pretreated TiN surfaces.</a> Journal of the Electrochemical Society. 155 (1), D10-D13 (2008).</li><li>Shiao, M. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+gold+dendritic+nanoflowers+deposited+on+titanium+nitride+for+photoelectrochemical+cells.">Novel gold dendritic nanoflowers deposited on titanium nitride for photoelectrochemical cells.</a> Journal of Solid State Electrochemistry. 22 (10), 3077-3084 (2018).</li><li>Shiao, M. H., Lin, C. T., Zeng, J. J., Lin, Y. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+gold+dendritic+nanoforests+combined+with+titanium+nitride+for+visible-light-enhanced+chemical+degradation.">Novel gold dendritic nanoforests combined with titanium nitride for visible-light-enhanced chemical degradation.</a> Nanomaterials. 8 (5), 282 (2018).</li><li>Carraro, C., Maboudian, R., Magagnin, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metallization+and+nanostructuring+of+semiconductor+surfaces+by+galvanic+displacement+processes.">Metallization and nanostructuring of semiconductor surfaces by galvanic displacement processes.</a> Surface Science Reports. 62 (12), 499-525 (2007).</li></ol>

The authors have nothing to disclose.

In this study, Au DNFs with multiple branch sizes were decorated on the surface of TiN/Si by using FAGRR. The deposition of the Au DNFs could be directly identified by a significant change in color. The thickness of the Au DNFs on TiN/Si increased to 5.10 &#177; 0.20 &#181;m within 15 min, and this increase in thickness can be expressed using the following linear equation: y = 0.296t + 0.649, where the time varied from 1 to 15 min.
In FAGRR, the metal deposition is affected b...

Gold nanoparticles have characteristic optical properties and localized surface plasmon resonances (LSPRs), depending on the size and shape of the nanoparticles1,2,3,4. Moreover, gold nanoparticles can significantly enhance plasmonic photocatalytic reactions5. Dendritic nanoforests stacked using gold nanoparticles have received considerable attention because of their noteworthy specific surface areas and robust LSPR enhancement6,7,8,9,10,11,12,13.
TiN is an extremely hard ceramic material and has remarkable thermal, chemical, and mechanical stability. TiN has distinctive optical properties and can be used for plasmonic applications with visible-to-near-infrared light14,15. Research has demonstrated that TiN can produce electromagnetic field enhancements, similar to Au nanostructures16. The deposition of copper17 or silver18,19,20 on TiN substrates for applications has been demonstrated. However, few studies have been performed on Au/TiN composite materials for applications. Shiao et al. have recently demonstrated potential applications of Au DNFs/TiN composites for photoelectrochemical cells21 and chemical degradation22.
Au can be synthesized on a TiN substrate by using a FAGRR23. The deposition condition of Au DNFs on TiN is crucial in the performance of applications. This study examines the growth of Au DNFs on a TiN-coated Si substrate.

<table border="0" cellpadding="0" cellspacing="0" style="width:911px;" width="912">
	<tbody>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">Acetone</td>
			<td style="width:321px;">Dinhaw Enterprise Co. Ltd.,Taipei, Taiwan</td>
			<td style="width:175px;"></td>
			<td style="width:182px;"></td>
		</tr>
		<tr height="49">
			<td height="49" style="height:49px;width:233px;">Isopropanol</td>
			<td style="width:321px;">Echo Chemical Co. Ltd., Miaoli, Taiwan</td>
			<td style="width:175px;">TG-078-000000-75NL</td>
			<td style="width:182px;"></td>
		</tr>
		<tr height="30">
			<td height="30" style="height:31px;width:233px;">Buffered Oxide Etch</td>
			<td style="width:321px;">Uni-onward Corp., Hsinchu, Taiwan&#160;</td>
			<td style="width:175px;">UR-BOE-1EA</td>
			<td style="width:182px;"></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:233px;">Chloroauric Acid</td>
			<td style="width:321px;">Alfa Aesar., Heysham, United Kingdom</td>
			<td style="width:175px;">36400.03</td>
			<td style="width:182px;"></td>
		</tr>
		<tr height="31">
			<td height="31" style="height:31px;width:233px;">N-Type Silicon Wafer</td>
			<td style="width:321px;">Summit-Tech Company, Hsinchu, Taiwan</td>
			<td style="width:175px;"></td>
			<td style="width:182px;"></td>
		</tr>
		<tr height="62">
			<td height="62" style="height:62px;width:233px;">High-Power Impulse Magnetron Sputtering System (HiPIMS)</td>
			<td style="width:321px;">Melec GmbH, Germany</td>
			<td style="width:175px;"></td>
			<td style="width:182px;">SPIK2000A&#160;</td>
		</tr>
		<tr height="55">
			<td height="55" style="height:55px;width:233px;">Scanning Electron Microscope (SEM)</td>
			<td style="width:321px;">JEOL, Japan</td>
			<td style="width:175px;"></td>
			<td style="width:182px;">JSM-7800F</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">Ion Sputter Coater</td>
			<td style="width:321px;">Hitachi, Japan</td>
			<td style="width:175px;"></td>
			<td>E-1030</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:233px;">X-Ray Diffractometer (XRD)</td>
			<td style="width:321px;">PANalytical, The Netherlands</td>
			<td style="width:175px;"></td>
			<td>X&#39;Pert PRO MRD</td>
		</tr>
	</tbody>
</table>

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.

Figure 1 depicts images of the Au DNFs/TiN/Si sample preparations. The silicon wafer was silvery white (Figure 1a). TiN/Si was golden yellow and had a homogeneous surface (Figure 1b), which indicated the uniform TiN coating on the silicon wafer. Au DNFs/TiN/Si was yellowish brown and less homogeneous on the surface (Figure 1c) because of the random distribution of Au DNF...

Watch this Scientific Journal Video about Growth of Gold Dendritic Nanoforests on Titanium Nitride-coated Silicon Substrates at JoVE.com

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

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.

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 ...

growth-gold-dendritic-nanoforests-on-titanium-nitride-coated-silicon

Universidad San Sebastian

Research

JoVE Journal

Chemistry

6.4K Views.  National Applied Research Laboratories. 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.

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

Template Directed Synthesis of Plasmonic Gold Nanotubes with Tunable IR Absorbance

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) membranes have been under development since the 1990's and have become a common method to template the synthesis of high aspect ratio nanostructures, mostly by electrochemical growth or pore-wetting. Recently, these membranes have become commercially available in a wide range of pore sizes and densities, leading to an extensive library of functional nanostructures being synthesized from AAO membranes. These include composite nanorods, nanowires and nanotubes made of metals, inorganic materials or polymers 3-10. Nanoporous membranes have been used to synthesize nanoparticle and nanotube arrays that perform well as refractive index sensors, plasmonic biosensors, or surface enhanced Raman spectroscopy (SERS) substrates 11-16, as well as a wide range of other fields such as photo-thermal heating 17, permselective transport 18, 19, catalysis 20, microfluidics 21, and electrochemical sensing 22, 23. Here, we report a novel procedure to prepare gold nanotubes in AAO membranes. Hollow nanostructures have potential application in plasmonic and SERS sensing, and we anticipate these gold nanotubes will allow for high sensitivity and strong plasmon signals, arising from decreased material dampening 15.

Solution-suspendable gold nanotubes with controlled dimensions can be synthesized by electrochemical deposition in porous anodic aluminum oxide (AAO) membranes using a hydrophobic polymer core. Gold nanotubes and nanotube arrays hold promise for applications in plasmonic biosensing, surface-enhanced Raman spectroscopy, photo-thermal heating, ionic and molecular transport, microfluidics, catalysis and electrochemical sensing.

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) ...

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 ...

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.

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 ...

Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide (CdSe@CdS) nanorod photocatalysts. Seeded rods are grown using a colloidal hot-injection method and then moved to an aqueous medium by ligand exchange. CdSe@CdS nanorods, an iridium precursor and other salts are mixed and illuminated. The deposition process is initiated by absorption of photons by the semiconductor particle, which results with formation of charge carriers that are used to promote redox reactions. To insure photochemical oxidative growth we used an electron scavenger. The photogenerated holes oxidize the iridium precursor, apparently in a mediated oxidative pathway. This results in the growth of high quality crystalline iridium oxide particles, ranging from 0.5 nm to about 3 nm, along the surface of the rod. Iridium oxide grown on CdSe@CdS heterostructures was studied by a variety of characterization methods, in order to evaluate its characteristics and quality. We explored means for control over particle size, crystallinity, deposition location on the CdS rod, and composition. Illumination time and excitation wavelength were found to be key parameters for such control. The influence of different growth conditions and the characterization of these heterostructures are described alongside a detailed description of their synthesis. Of significance is the fact that the addition of iridium oxide afforded the rods astounding photochemical stability under prolonged illumination in pure water (alleviating the requirement for hole scavengers).

A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide ...

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 ...

Hydroquinone Based Synthesis of Gold Nanorods

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the synthetic methods for the preparation of gold nanorods are still not fully optimized. In this paper we describe a new, highly efficient, two-step protocol based on the use of hydroquinone as a mild reducing agent. Our approach allows the preparation of nanorods with a good control of size and aspect ratio (AR) simply by varying the amount of hexadecyl trimethylammonium bromide (CTAB) and silver ions (Ag+) present in the "growth solution". By using this method, it is possible to markedly reduce the amount of CTAB, an expensive and cytotoxic reagent, necessary to obtain the elongated shape. Gold nanorods with an aspect ratio of about 3 can be obtained in the presence of just 50 mM of CTAB (versus 100 mM used in the standard protocol based on the use of ascorbic acid), while shorter gold nanorods are obtained using a concentration as low as 10 mM.

This paper describes a protocol for the synthesis of gold nanorods, based on the use of hydroquinone as reducing agent, plus the different mechanisms for controlling their size and aspect ratio.

Gold nanorods are an important kind of nanoparticles characterized by peculiar plasmonic properties. Despite their widespread use in nanotechnology, the ...

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. ...

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of their interactions with cell membranes, lipid bilayers, and viruses. The hydrophilic ligands make these particles colloidally stable in aqueous solutions and the combination with hydrophobic ligands creates an amphiphilic particle that can be loaded with hydrophobic drugs, fuse with the lipid membranes, and resist nonspecific protein adsorption. Many of these properties depend on nanoparticle size and the composition of the ligand shell. It is, therefore, crucial to have a reproducible synthetic method and reliable characterization techniques that allow the determination of nanoparticle properties and the ligand shell composition. Here, a one-phase chemical reduction, followed by a thorough purification to synthesize these nanoparticles with diameters below 5 nm, is presented. The ratio between the two ligands on the surface of the nanoparticle can be tuned through their stoichiometric ratio used during synthesis. We demonstrate how various routine techniques, such as transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and ultraviolet-visible (UV-Vis) spectrometry, are combined to comprehensively characterize the physicochemical parameters of the nanoparticles.

Amphiphilic gold nanoparticles can be used in many biological applications. A protocol to synthesize gold nanoparticles coated by a binary mixture of ligands and a detailed characterization of these particles is presented.

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of ...

Assembly of Gold Nanorods into Chiral Plasmonic Metamolecules Using DNA Origami Templates

The inherent addressability of DNA origami structures makes them ideal templates for the arrangement of metal nanoparticles into complex plasmonic nanostructures. The high spatial precision of a DNA origami-templated assembly allows controlling the coupling between plasmonic resonances of individual particles and enables tailoring optical properties of the constructed nanostructures. Recently, chiral plasmonic systems attracted a lot of attention due to the strong correlation between the spatial configuration of plasmonic assemblies and their optical responses (e.g., circular dichroism [CD]). In this protocol, we describe the whole workflow for the generation of DNA origami-based chiral assemblies of gold nanorods (AuNRs). The protocol includes a detailed description of the design principles and experimental procedures for the fabrication of DNA origami templates, the synthesis of AuNRs, and the assembly of origami-AuNR structures. In addition, the characterization of structures using transmission electron microscopy (TEM) and CD spectroscopy is included. The described protocol is not limited to chiral configurations and can be adapted for the construction of various plasmonic architectures.

We describe the detailed protocol for the DNA origami-based assembly of gold nanorods into chiral plasmonic metamolecules with strong chiroptical responses. The protocol is not limited to chiral configurations and can be easily adapted for the fabrication of various plasmonic architectures.

The inherent addressability of DNA origami structures makes them ideal templates for the arrangement of metal nanoparticles into complex plasmonic ...

Gold Nanoparticle Modified Carbon Fiber Microelectrodes for Enhanced Neurochemical Detection

For over 30 years, carbon-fiber microelectrodes (CFMEs) have been the standard for neurotransmitter detection. Generally, carbon fibers are aspirated into glass capillaries, pulled to a fine taper, and then sealed using an epoxy to create electrode materials that are used for fast scan cyclic voltammetry testing. The use of bare CFMEs has several limitations, though. First and foremost, the carbon fiber contains mostly basal plane carbon, which has a relatively low surface area and yields lower sensitivities than other nanomaterials. Furthermore, the graphitic carbon is limited by its temporal resolution, and its relatively low conductivity. Lastly, neurochemicals and macromolecules have been known to foul at the surface of carbon electrodes where they form non-conductive polymers that block further neurotransmitter adsorption. For this study, we modify CFMEs with gold nanoparticles to enhance neurochemical testing with fast scan cyclic voltammetry. Au3+ was electrodeposited or dipcoated from a colloidal solution onto the surface of CFMEs. Since gold is a stable and relatively inert metal, it is an ideal electrode material for analytical measurements of neurochemicals. Gold nanoparticle modified (AuNP-CFMEs) had a stability to dopamine response for over 4 h. Moreover, AuNP-CFMEs exhibit an increased sensitivity (higher peak oxidative current of the cyclic voltammograms) and faster electron transfer kinetics (lower &#916;EP or peak separation) than bare unmodified CFMEs. The development of AuNP-CFMEs provides the creation of novel electrochemical sensors for detecting fast changes in dopamine concentration and other neurochemicals at lower limits of detection. This work has vast applications for the enhancement of neurochemical measurements. The generation of gold nanoparticle modified CFMEs will be vitally important for the development of novel electrode sensors to detect neurotransmitters in vivo in rodent and other models to study neurochemical effects of drug abuse, depression, stroke, ischemia, and other behavioral and disease states.

In this study, we modify carbon-fiber microelectrodes with gold nanoparticles to enhance the sensitivity of neurotransmitter detection.

For over 30 years, carbon-fiber microelectrodes (CFMEs) have been the standard for neurotransmitter detection. Generally, carbon fibers are aspirated into ...