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In this work, the morphological and structural evolution of gold nanodots deposited on Si substrates has been monitored for 2.4 x [10.sup.3] h. Gold nanodots on Si are of great scientific interest because they can be used in numerous ways, for example as subwavelength antennas in plasmonics, as electrical contacts in nanometric devices, or as catalysts for the formation of quasi-1dimensional nanostructures. Their characteristics have been studied in a very large number of papers in literature, and among the several aspects, it is known that continuous Au films peculiarly interact with Si by interdiffusion even at room temperature. It would be expected that also small nanostructures could undergo to an interdiffusion and consequent modifications of their structure and shape after aging. Despite the cruciality of this topic, no literature papers have been found showing a detailed morphological and structural characterization of aged Au nanodots. Au nanoparticles have been deposited by sputtering on Si and stored in air at temperature between 20 and 23 °C and humidity of about 45%, simulating the standard storage conditions of most of the fabrication labs. The morphological and structural characterizations have been performed by bright field transmission electron microscopy (TEM). A specific procedure has been used in order to avoid any modification of the material during the specimen preparation for the TEM analysis. A digital processing of the TEM images has allowed to get a large statistical analysis on the particles size distribution. Two different types of nanoparticles are found after the deposition: pure gold crystalline nanodots on the Si surface and gold amorphous nanoclusters interdiffused into the Si subsurface regions. While the nanodots preserve both morphology and structure all over the time, the amorphous agglomerates show an evolution during aging in morphology, structure, and chemical phase. Keywords Interfaces. Gold. Silicon. Nanodots. Transmission electron microscopy. Aging, Introduction Gold nanodots deposited on silicon are of significant importance because this material presents a large number of applications like as subwavelength antennas in plasmonic applications, or as catalysts for [...]

Ceria-based gold catalysts were successfully de-posited on ferritic stainless steel (Fecralloy) and aluminium monoliths. The prepared monolithic and reference powder catalysts were characterized by means of [S.sub.BET], X-ray diffraction, glow discharge optical emission spectroscopy and scanning electron microscopy--energy dispersive X-ray analysis techniques and tested in the CO oxidation reaction. Characterization results put in evidence the diffusion of cations from the catalytic layer on the surface of the monoliths to the metallic oxide scale and inversely, from the oxide scale to the catalysts, thus altering the catalytic formulation and affecting the CO oxidation properties of the catalytic device. The extension and nature of the modifications produced depend on the nature of the catalysts and the metallic substrate, as well as the reaction conditions applied. These facts must be considered when gold catalysts are supported on metallic-structured devices. Keywords Metallic monolith. Fecralloy. Anodised aluminium. Gold catalysts. CO oxidation. GD-OES, Published online: 18 August 2013 © The Author(s) 2013. This article is published with open access at SpringerLink.com Introduction Heat and mass transport properties are strongly enhanced by using structured [...]

In this work, we have investigated the electrical characteristics of Au-Cu-n-InP Schottky contacts by current--voltage (I-V) and capacitance-voltage (C-V) measurements in the temperature range 260--420 K in steps of 20 K. The diode parameters, such as the ideality factor, n, and zero-bias barrier height, [Φ.sub.b0], have been found to be strongly temperature dependent. It has been found that the zero-bias barrier height, [Φ.sub.b0](1-V), increases and the ideality factor, n, decreases with an increase in temperature. The forward I-V characteristics are analyzed on the basis of standard thermionic emission (TE) theory and the assumption of gaussian distribution of barrier heights, due to barrier inhomogeneities that prevail at the metal-semiconductor interface. The zero-bias barrier height [Φ.sub.b0] versus 1/2kT plot has been drawn to obtain the evidence of a gaussian distribution of the barrier heights. The corresponding values are [Φ/sub.b0] = 1.16 eV and [σ.sub.0] = 159 meV for the mean barrier height and standard deviation, respectively. The modified Richardson plot has given mean barrier height, Φ.sub.b0], and Richardson constant, [A.sup.**], as 1.15 eV and 7.34 [Acm.sup.-2][K.sup.-2], respectively, which is close to the theoretical value of 9.4 [Acm.sup.-2][K.sup.-2]. Barrier heights obtained from C-V measurements are higher than those obtained from I-V measurements. This inconsistency between Schottky barrier heights (SBHs) obtained from I-V and C-V measurements was also interpreted. The temperature dependence of the I-V characteristics of the Au-Cu-n-InP Schottky diode has been explained on the basis of TE mechanism with gaussian distribution of the SBHs. PACS Nos: 73.30.+y, 73.40.Ei Nous etudions ici les caracteristiques electriques de diodes Schottky Au-Cu-n-InP a l'aide de mesures courantvoltage (I-V) et capacitance-voltage (C-V) dans le domaine de temperatures entre 260 et 420 K par sauts de 20 K. Nous trouvons que les parametres de la diode, comme le facteur d'idealite, n, et la hauteur de barriere a zero polarisation, [Φ.sub.b0], dependent fortement de la temperature. Nous trouvons qu'avec l'augmentation de la temperature, [Φ.sub.b0](I-V) augmente, alors que le facteur d'idealite, n, diminue. Nous analysons les caracteristiques I-V de conduction sur la base de la theorie d'emission (TE) thermoionique standard et sur l'hypothese d'une distribution gaussienne des hauteurs de barriere, due aux inhomogeneites de barriere qui prevalent a l'interface metal--semiconducteur. Nous presentons le graphique de [Φ.sub.b0] en fonction de 1/2kT, afin de demontrer la distribution gaussienne des hauteurs de barriere. Nous obtenons une hauteur moyenne [Φ.sub.b0] = 1,16 eV, avec une deviation standard [σ.sub.0] = 159 meV. Le graphique de Richardson modifie a donne les valeurs de [Φ.sub.b0] = 1,15 eV pour la hauteur et de [A.sup.**] = 7,34 [Acm.sup.-2][K.sup.-2] pour le parametre de Richardson respectivement, cette derniere valeur etant proche de la valeur theorique de 9,4 [Acm.sup.-2][K.sup.-2]. Les hauteurs de barriere obtenues des mesures C-V sont plus hautes que celles obtenues des mesures I-V. Nous interpretons aussi cette incoherence entre les hauteurs de barriere de Schottky (SBHs) obtenues de mesures I-V et C-V. Nous expliquons la dependance en temperature des caracteristiques I-V de la diode de Schottky Au-Cu-n-InP sur la base du mecanisme TE avec une distribution gaussienne des SBHs. [Traduit par la Redaction], 1. Introduction Indium phosphide (InP) is an attractive III-V compound semiconductor material because of its advantages for solar cells, laser diodes, photo-detectors and high speed metal-insulator-semiconductor field effect transistors, microwave [...]

We provide a highly sensitive and selective assay to detect [Hg.sup.2+] in aqueous solutions using gold nanoparticles modified with quaternary ammonium group-terminated thiols at room temperature. The mechanism is the abstraction of thiols by [Hg.sup.2+] that led to the aggregation of nanoparticles. With the assistance of solar light irradiation, the detection limit can be as low as 30 nM, which satisfies the guideline concentration of [Hg.sup.2+] in drinking water set by the WHO. In addition, the dynamic range of detection is wide (3 x [10.sup.-8]-1 x [10.sup.-2] M). This range, to our best knowledge, is the widest one that has been reported so far in gold nanoparticle (AuNP)-based assays for [Hg.sup.2+]. 10.1021/ac1021503

The article studies the performance and dependability of gold (Au) and platinum (Pt) single-layer nanocrystal (NC)-based Flash memory devices for NAND application using CMOS-compatible process flow. Findings reveal that annealing-temperature-dependent gate is practical in Au devices using analytical methods.

The electrical, mechanical and thermal properties of Bi-2223/AgAu tapes and stacks manufactured by EHTS and Sumitomo are characterized. The mechanically unstabilized tapes have reached higher critical currents but lower mechanical limits and the tapes from both suppliers have exceeded the specified critical current.

The functionalization of gold nanorods with a thiol derivative of ruthenium (II) tribipyridyl complex in dodecanethiol is described. The results suggest that the size and shape of the gold nanorods impact the quenching of the excited state to proceed via an energy transfer mechanism and those gold rods are capable to deactivate excited ruthenium.

The photoreduction of adsorbed copper ions onto Au nanoparticles, on an indium tin oxide (ITO) electrode in an aqueous electrochemical cell, is studied as a function of applied voltage and laser intensity. The numerical simulation of the Butler-Volmer kinetic equation has predicted several orders of magnitude increase in current for a temperature rise of a few Kelvin, which is sufficient to cause measurable difference in the surface properties of gold nanoparticles and facilitate the deposition of copper.

Although significant progress has been made in understanding the behavior of natural nanoparticles in Earth's critical zone (i.e., surface and near-surface environment), little is known about nanoparticle stability in higher-temperature environments where they are increasingly being found. Here we report the first direct observations of the thermal behavior of natural nanoparticles at near atomic scale, revealing that their thermal stability is dependent on particle size and on the surrounding host mineral. Native Au nanoparticles (mean diameter ~4 nm) incorporated in arsenian pyrite from refractory Au ores were observed under the transmission electron microscope during in situ heating to 650 [degrees]C. While isolated Au nanoparticles melt, with the melting point being a function of size, we show that when incorporated in arsenian pyrite, Au nanoparticles become unstable unless the nanoparticle size distribution coarsens by diffusion-driven, solid-state Ostwald ripening. This change in nanoparticle stability starts above 370 [degrees]C, setting an upper temperature and size limit for the occurrence of nanoparticulate Au in refractory sulfides. These findings not only provide new insights into the behavior of nanoparticulate Au and other metals during geological processes and throughout their metallurgical recovery from refractory ores, but also provide a new tool to define the thermal history of nanoparticle-bearing geologic and planetary materials. Keywords: nanoparticles, gold, Ostwald ripening, Carlin-type gold, epithermal.

Quantum size effects for the case 0.22 less than t[l.sub.pt] less than 2.45, where l is the electron mean free path and t the film thickness are analyzed. It is seen that quantum size effects are relevant and [DELTA][S.sub.F] obeys a nonlinear law .

The seedless synthesis of gold nanorods at high temperatures up to 97 degree Celsius is demonstrated by using the correct silver nitrate concentration. A decrease of nanorod length was observed with increase in temperature while the width stayed constant throughout the temperature range.

A study demonstrates that, after ion irradiating 60 nm thick Au films on Si substrates with 230 KeV [Ar.sup.} ions, annealing conditions could be found leading to strong diffusional contrasts between bombarded and unbombarded areas. While Au readily diffuses into the bombarded part of the sample at 310 degree Celsius, its diffusion is still completely blocked under identical conditions in the unbombarded parts.

This paper reports the effects of a multiple zincation process on the Al bond pad surface prior to electroless nickel immersion gold deposition. The study of multiple zincation comprises the surface topography and morphology of the appearance of the Al bond pad. In addition, by comprehension of the effects of the multiple zincation process, the study includes investigating the Al dissolution rate and adhesion strength between eutectic a 37 Pb/63 Sn solder ball and an under bump metallurgy (UBM) interface. Scanning electron microscopy, energy dispersive x-ray, atomic force microscopy, focused ion beam, and an lntellectest STORM series FA1500 shear tester were used as analytical tools in this study. The results suggest that the first zincation process follows the contour of the initial bond pad. The second zincation produces a slightly better surface appearance with a smooth and fine Zn crystallite. The Zn crystallites become a continuous film with the deposits looking like an island formation after the third zincation. The smooth surface of the third zincation, as an effect of multiple zincation, is later transferred to Ni and Au surfaces. The smooth surface of the UBM leads to a better shear strength with only a minimum Al dissolved. [DOI: 10.1115/1.2229223] Keywords: zincation, electroless nickel immersion gold (ENIG), under bump metallurgy (UBM)

The heats of adsorption of two linear CO species adsorbed on the Au(super o) particles and on the Ti(super +delta) sites of a 1% Au/TiO2 catalyst are determined as the function of their respective coverage by using the AEIR procedure (adsorption equilibrium infrared spectroscopy) developed. The study shows that the mathematical formalism supporting the AEIR procedure can be applied to literature data on Au-containing solids.

The structure and dynamics of partial monolayers of C(sub 60) on the Au(111) surface were observed by scanning tunneling microscopy (STM) under ambient conditions. The motion of surface-adsorbed C(sub 60) is predominantly the result of thermal diffusion and the extent of pertubation by the STM tip is determined to be minimal, using a quantitative analysis of a time series of STM images.

The single-stranded DNA adsorbs on negatively charged gold nanoparticles is reported. Its rate of adsorption depends on the sequence length and temperature.

A single step process for the synthesis and self-assembly of ca. 3nm gold nanoparticles by 4-aminothiophenol (ATP) in water -DMF is demonstrated. The results indicate the involvement of both ithiol and amine groups in the reduction of AuCl(super -) ions, which simultaneously compete for attachment on the surface of gold nanoparticles.

A study is conducted to examine the temperature dependence of blinking in SERS signals, which is abrupt repeated intensity and peak frequency fluctuation. It is found that the blinking observed at room temperature is suppressed by cooling to 77 K for one-third to one-fourth of the particles and recovered by warming to RT.

The effects of pH on the surface reconstruction of Au(100), on CO oxidation, and on the oxygen reduction reaction (ORR) are discussed by a combination of SXS, FTIR spectroscopy, and RRDE measurements. It is proposed that the pH-dependent kinetics of the ORR on Au(100) can be unraveled by finding the relationship between kinetic rates.

The properties of a liquidlike layer (LLL) at the gold/frozen electrolyte interface are studied by using the quartz crystal microbalance (QCM). It was found that at temperatures well below the melting point of the electrolyte, in the range of -2 to -7 degree C, the QCM immersed in a frozen electrolyte shows detectable resonance, the parameters of which depends strongly on temperature.

Studies of anions and electrons desorbed from the Au-C-deposited Y2O3-stabilized ZrO2 (YSZ) surfaces by newly developed time-of-flight (TOF) system are presented. It is observed that the anion emission may be controlled by desorption from the Au surface in the low-temperature region and by electron desorption to provide fresh three-phase boundaries or the electrochemical reaction to form O(super 2-)(s) in the high temperature region.

A study is conducted to compare investigation of energy relaxation dynamics of gold nanoparticles and gold-polypyrrole encapsulated nanoparticles. The results indicate that directly attached polypyrroles provide fast thermal energy transfer pathways for the core gold nanoparticles.

The statistical thermodynamic theory of the absorbate-induced surface stress of adion monolayer on Au(111) is established by using the lattice gas model. The effective pair interaction energy, surface stress, and its components due to various intermolecule forces, and the area elasticity modulus k(sub 2D)(super -1) in the chloride adlayer at the Au(111) electrode surface, are calculated.

The scanning of probe microscopy upon thermal decomposition on top of graphite and mica substrates helps to observe ligand-stabilized Au(sub 55) clusters. The result indicates that the Au residuals after thermal decomposition, which takes place at same temperature as for mica, rapidly aggregate upon increasing the temperature.

Scanning tunneling microscopy (STM) is utilized in situ to image the structures formed by neat dimethyl sulfoxide (DMSO) on Au surfaces at room temperature. The STM reveals that DMSO forms ordered arrays on Au(111) lattices but is substantively disordered on the new lower Miller index faces of Au.

The various effects of the gigaelectron volt Au-ion irradiation/postannealing processes on the electron field emission (EFE) and other characteristics of the ultrananocrsytalline diamond films are analyzed. These proceses are shown to lead to a significant enhancement in the EFE properties of the films.

A micromechanism of thermosonic gold wire bonding is described by analyzing its interfacial characteristics as a result of the bonding process, which has included the fragmentation of the native aluminum oxide layer on Al pads and formation of initial intermetallic compounds (IMCs). The formation mechanism of IMCs is described by using the effective heat of formation theory.

Gold-coated silicon wafers are annealed in a [N.sub.2] ambient containing a low residual [O.sub.2] concentration. The comparison with known thermodynamic data for the oxidation of Si and vapor-pressures of reactants has shown that nanowire growth is mediated by a vapor-liquid-solid mechanism in which the dominant vapor-phase source of reactants is SiO produced by the active oxidation of Si.

Perpendicular magnetic anisotropy (PMA) is induced in Co/Ni multilayers when they are grown on a (111) textured Au seed layer and the anisotropy has increased with increasing Au thickness due to improved crystallinity. The results have shown that the PMA in Co/Ni multilayers are improved by annealing up to 350 [degree]C, which is needed for the thermal stability of spin transfer torque memories.

The surface thermal lensing effect is used for measuring thermal conduction across thin films optically. Thermal conductivity in gold films has dropped when the film thickness is reduced and the results for silver, tin and aluminum are presented.

The article presents a new technique, which employs the fluorescent quantum dots for measuring the local temperature observed in the vicinity of the electromagnetically heated magnetic and gold nanoparticles. The temperature is shown to significantly increase with the heat dissipated by the nanoparticles, hence leading to complete change in the molecules attached to them.

Several studies are conducted to explain the various different forward bias current-voltage characteristics exhibited by the different Au/n-Si Schottky barrier diodes (SBDs) with Zn doped poly(vinyl alcohol) interfacial layer. The analysis also helps in determining the activation energy, Richardson constant and other parameters exhibited by the diodes at different temperature ranges.

The impact of the rf microelectromechanical system switch contact voltage on the gold-on-gold contacts at the cryogenic temperatures is determined. The values of contact resistance of the system are shown to be much lower than that observed at high contact voltages, hence demonstrating the dependence of the contact currents on the heating and softening effects.

The temperature dependence of capacitance-voltage (C-V) and conductance-voltage (G/w-V) characteristics of Au/polyvinyl alcohol (Co,Zn-doped)/n-Si Schottky di odes (SDs) is examined by considering series resistance effect. The high frequency [C.sub.m] and [G.sub.m]/w values measured under both reverse and forward bias are corrected for the effect of series resistance in order to obtain the real diode capacitance and conductance.

A Bridgman-type cell is used for measuring the melting curve of Mg, Mn, Cu, Ag, Au, Zn, Cd, Al, In and Pb up to 12 GPa. The results have shown that the electronic structure of an element has played a major role in determining the pressure dependence of its melting curve.

The atomic force microscopy method is used for studying the evolution of the Au film morphology as a function of the film thickness and annealing time. The study of the evolution of the mean Au clusters size as a function of annealing time has helped in identifying the thermal-induced self-organization mechanism in a surface diffusion limited ripening of 3D structures and also the surface diffusion coefficient of Au on Si(111) is estimated.

Samples composted of chemically prepared Au nanoparticles embedded within a planar silica film are used as model system for examining the evolution of a second phase under irradiation when the temperature and the ion stopping power are changed. The studies have shown that the complete dissolution of the NPs have led to the formation of smaller precipitates with a narrower size distribution at room temperature.

The simple reduction of aurichloride in a limited reaction temperature range around 85 degree [Celsius] are used to synthesize the homogeneous Au nanowires with 1.5 nm diameters and lengths of over 100 [mu]m. The various shapes of Au nanostructures produced by the unique and different synthesis method are found to be significantly dependent on the reaction temperature.

In situ ambient pressure X-ray photoelectron spectroscopy is used for studying the interaction of [O.sub.2] with gold foil and gold nanoparticles grown by thermal deposition on Ti[O.sub.2](110). X-ray irradiation is very effective in promoting gold oxidation on both surfaces in the presence of [O.sub.2].

Low-temperature catalysts of mesoporous [Co.sub.3][O.sub.4] and Au/[Co.sub.3][O.sub.4] with high catalytic activities for the trace ethylene oxidation are described. Gold nanoparticles present on [Co.sub.3][O.sub.4] have produced surface-active oxygen species and have promoted ethylene oxidation to achieve a 76% conversion, which is the highest conversion till date.