Influence Of Au Research Articles

Ohmic contacts to n-type SiC: Influence of Au and Ta intermediate layers

In this study, the optimization of metal-semiconductor contacts to reduce the contact resistance of ohmic contacts on n-type 4H-SiC. The commonly used Ni/Au metal scheme served as a reference. We introduced two novel metal schemes: (i) incorporating a thin interfacial Au layer (2 nm) into Ni/Au, resulting in Au/Ni/Au, and (ii) introducing a thin intermediate barrier layer of Ta (20 nm) into Ni/Au, resulting in Ni/Ta/Au. Rapid thermal annealing (RTA) is performed at different temperatures and durations and the electrical characteristics of the contacts are measured. X-ray diffraction analysis was employed to investigate the intermediate phases formed during annealing. In the Au/Ni/Au metal scheme, the presence of Au at the interface promoted the formation of additional phases of nickel-silicide (Ni3Si and Ni3Si2). Compared to the traditional Ni/Au scheme, the modified metal schemes led to lower surface roughness and reduced contact resistance. Specific contact resistivity values are calculated, 2.2 × 10−5 Ω-cm2 for Ni/Au, 1.37 × 10−5 Ω-cm2 for Au/Ni/Au, and 4.84 × 10−5 Ω-cm2 for Ni/Ta/Au. This research offers valuable insights for the selection of metal schemes in designing ohmic contacts on n-type SiC, with potential applications in various semiconductor device technologies.

Influence of Au0 metallic particles on NIR laser emission of Yb3+ ions in Li2O−HfO2−SiO2 glass ceramic

This study consists of the synthesis, characterization, and analysis of photoluminescence (PL) spectra for Li2O−HfO2−SiO2−Yb2O3 glass ceramics sensitized with small amounts of Au2O3. Using the results of XRD and X-ray photoelectron spectroscopy (XPS) studies indicated a progressive reduction of Au3+ ions into Au0 metallic particles (MPs) with increase of Au2O3 content. Investigations into the infrared spectra highlighted a growing concentration of induced defects in the samples due to the increased proportion of Au0 MPs. Optical absorption (OA) spectra exhibited a distinct band attributed to the 2F7/2 → 2F5/2 transition of Yb3+ within wavelength range of 800–980 nm. Furthermore, a wide absorption band linked to the surface plasmon resonance (SPR) of Au0 MPs was identified in the visible region. PL spectra, recorded at λexc = 450 nm, revealed a band between 980 to 1025 nm, associated with the 2F5/2 → 2F7/2 transition of Yb3+ ions. Another emission band was observed due to the sp → d transition of Au0 MPs within the visible region. Observed enhanced PL emission from Yb3+ ions in the NIR range was ascribed to the energy transfer from Au0 MPs to Yb3+ ions. Ultimately, it was deduced that Au0 MPs played a pivotal role in enhancing the PL output of Yb3+ ions in the Li2O−HfO2−SiO2 glass ceramic. Thus, glass ceramics incorporating an optimal concentration of Au2O3 hold significant potential as materials for NIR lasers.

Influence of Au, Pt, and C Seed Layers on Lithium Nucleation Dynamics for Anode-Free Solid-State Batteries.

In the concept of anode-free lithium-ion batteries, cells are manufactured with a bare anode current collector where the lithium metal anode is electrochemically formed from the lithium-containing cathode during the first charge cycle. While this concept has many attractive aspects from a manufacturing and energy density standpoint, stable plating and stripping remain challenging. We have investigated gold, platinum, and amorphous carbon as seed layers placed between the copper current collector and the lithium phosphorus oxynitride thin-film solid electrolyte. These layers guide lithium nucleation and improve the plating and stripping dynamics. All seed layers facilitate reversible lithium plating and stripping even at high current densities up to 8 mA cm-2. Of particular note is the amorphous carbon seed layer, which allowed a significant reduction in plating potential from 300 mV to as low as 50 mV. These results underscore the critical role of seed layers in improving the efficiency of anode-free solid-state batteries and open the door to simplified manufacturing of anode-free battery designs.

Influence of Au on the nucleation of Ag nanoparticles in GeO2-PbO glasses and characterization of their ultrafast third-order nonlinear responses within the plasmon resonance region

Germanate (GeO2-PbO) glasses doped with AgNO3 and co-doped with AgNO3 and Au2O3 were synthesized via melting-quenching technique. Silver nanoparticles were nucleated within the sample doped only with AgNO3 and its plasmon resonance was characterized. The influence of the addition of Au2O3 on the silver nanoparticles nucleation and on the spectroscopic properties of the produced composite materials were investigated using TEM, STEM and UV–Vis spectroscopy. Using the nonlinear ellipse rotation technique, the pure electronic contribution to the samples nonlinear refraction and absorption were characterized within the visible range, including the localized surface plasmon (LSP) resonance wavelength of the metallic nanoparticles. The real and imaginary parts of the third-order nonlinear susceptibility of the glass, composite samples and of the individual nanoparticles were also obtained. In addition, all-optical switching figures of merit of the samples were also calculated. From these results, the dispersion curves of the electronic contribution to the third-order susceptibility of the metallic nanoparticles were obtained and two figures of merit for all-optical switching of the composite materials were calculated. The studied samples are potential candidates for all-optical switching applications with exception to the one with the highest volume filling factor, whose linear and nonlinear absorption coefficients associated to the local field factor deplete the material performance around the LSP resonance wavelength. As far as we know nonlinear ellipse rotation technique was not used before to evaluate the influence of metallic nanoparticles on the nonlinear optical properties of glasses.

Voltammetric studies on the interaction of ds-DNA with anti-cancer agents imatinib and erlotinib – Comparison of Au and Pt nanoparticle effects to drug-DNA complex formation

The interactions of imatinib (IMA) and erlotinib (ERL) with calf-thymus double-stranded deoxyribonucleic acid (ds-DNA) were studied by using monometallic (Au and Pt) and bimetallic (Au + Pt) nanoparticles modified DNA biosensors. The prepared electrochemical biosensors were designed to show the interaction between IMA (or ERL) and ds-DNA. The characterization of the prepared sensors was carried out by energy-dispersive X-ray spectroscopy (EDX). The influence of Au, Pt, and Au + Pt nanoparticles in the modified biosensor was investigated to elucidate the interaction between the anti-cancer drugs and ds-DNA. The interaction was realized based on the electrochemical oxidation signal (at about +0.80 V) of the guanine (dGu) base of ds-DNA by differential pulse voltammetry (DPV) in pH 4.8 acetate buffer. The effect of the nanoparticle’s concentration and interaction time of IMA (and ERL) with ds-DNA on the electrochemical response of dGu were optimized. The results showed that Au + Pt nanoparticles, especially for IMA, significantly affected the binding constant value of the drugs to ds-DNA. Interaction studies have also shown that the binding mode for IMA and ERL could be intercalation and groove binding and the binding constant values were found to be 68.3 × 106 M−1 and 27.3 × 107 M−1, respectively.

Influence of Au, Ag, and Cu Adatoms on Optical Properties of TiO2 (110) Surface: Predictions from RT-TDDFT Calculations

In this paper, real-time time-dependent density-functional theory (RT-TDDFT) calculations are performed to analyze the optical property and charge transitions of a single noble metal atom deposited on rutile TiO2 (110) surface. The model structures are built reflecting the equilibrium positions of deposited adatoms atop the TiO2 surface. The absorption spectra are calculated for all model structures under study. To provide deeper insight into photo-absorption processes, the transition contribution maps are computed for the states of deposited adatoms involved in transitions. Assuming the photon energy is enough to overcome the band gap of TiO2 (∼3 eV), the photogenerated electrons of TiO2 seem to be partly accumulated around deposited Au atoms. In contrast, this is rarely observed for deposited Ag and Cu atoms. Based on our calculations, we have identified the transition state mechanism that is important for the design strategy of future photocatalytic materials.

Stabilność komponenta sieciującego warstwę receptorową biosensora po dodaniu nanocząstek złota

In this study, the stability of the receptor layer component of a biosensor after addition of gold nanoparticles was investigated. Accelerated conformational changes under the influence of Au were demonstrated. The relative percentage changes over time between the pure protein and the Au doped protein were calculated. It was shown that these changes are greater with time and exceed 20 % in the last days of the experiment.

Influence of Au, Cu, Pd added in Ag alloy on stability and electronic structure of Ag/Al interface by first-principles calculations

The first-principles calculation method based on density functional theory(DFT) were performed to study the effect of the alloying elements X added in the Ag alloy on the stability and electronic structure of the Ag(19,x)/Al20 (X=Au, Cu and Pd) interface. The calculation results show that the Ag(111)/Al(111) interface is the most stable interface geometry, which has the highest Wsep = 1.378 J/m2 and the lowest γint = 0.248 J/m2. The most significant volume increase of the interface was observed when substituting with Au, and the Wsep is reduced to 1.016 J/m2, indicating the stability of Ag/Al interface decreases remarkably. While the effect of doping Pd elements in Ag alloy on the interface stability is not obvious. In addition, the electronic structure is inferred that the strong covalent bonding is formed between Ag and Al at the interface. The average bond population of Al(1)-Ag(1) and Al(2)-Ag(2) in Ag/Al interface decreases when doping with Au and Cu, suggesting the covalence feature of Ag-Al bond is weakened, while doping with Pd increases the covalence.

Влияние ауто- и ксеногенных фибробластов и дермального эквивалента на содержание макрофагов в грануляционной ткани ишемизированной раны кожи на 12 сутки регенеративного гистогенеза

Влияние ауто- и ксеногенных фибробластов и дермального эквивалента на содержание макрофагов в грануляционной ткани ишемизированной раны кожи на 12 сутки регенеративного гистогенеза

Influence of Au on Ge Crystallization and Its Thermoelectric Properties in a Au-induced Ge Crystallization Technique

Poly-crystalline Ge (pc-Ge) thin films were prepared on a SiO2/Si substrate using Au-induced crystallization (GIC) of amorphous Ge (a-Ge) with an annealing temperature around the eutectic point of Au-Ge alloy system (361ºC) in order to shorten the annealing time. Bilayer thin films of Au (20 nm)/a-Ge (100 nm) were used as a precursor material and annealed at 300, 400, and 500 ºC for 60 min, which successfully leads to the formation of pc-Ge layers. Characterizing the prepared Ge layers, the crystallographic properties indicated that the metal catalyst Au plays a notable role of enhancing both the crystallization and the island formation of Ge layers. It was also shown that the pc-Ge hardly contains Au atoms. Therefore, the Seebeck coefficient was hardly influenced by Au atoms since they do not act as a carrier source. In addition, the thermal conductivity of the pc-Ge film prepared by the GIC method was higher than that formed without Au, which is not due to the Au catalyst itself but due to the crystallinity of Ge film enhanced by the Au atoms.

The nature of the Au–N bond in gold(iii) complexes with aromatic nitrogen-containing heterocycles: the influence of Au(iii) ions on the ligand aromaticity

Aromatic character of nitrogen-containing rings is decreased upon gold(iii) coordination.

The influence of Au and Pt electrodes on the stability of TiO2 under UV light activation for sensing formaldehyde in moisture circumstances

The structural stability of TiO2 thick films on Au and Pt electrodes was investigated under UV light activation for sensing formaldehyde in moisture circumstances. A chameleon phenomenon of TiO2 on the anode was found on the Au electrode samples, while no color changed on the Pt samples. The discolored (puce) TiO2 powders were characterized by X-ray photoelectron spectroscopy, where the generation of Ti3+ was verified. Different mechanisms that caused the disparities between the Au and Pt ones were discussed in detail. With the purpose of further evaluating the gas sensing performance stability, four test circles were performed. The Au electrode samples emerged an irreversible drift, while the Pt samples perfectly recovered to initial state undergoing a transitory 300°C thermal cycle. The results in this paper show that Pt electrode is a suitable choice for TiO2 sensing formaldehyde in moisture circumstances.

Influence of Au(III) Interactions with Chitosan on Gold Nanoparticle Formation

Potentiometry, electronic spectroscopy, and X-ray absorption (XAS) experiments were carried out to monitor the course of the complexation reaction between AuCl4– and glucosamine moieties (GLA) of chitosan molecules. The disappearance of the ligand (π)–metal (σ*) charge transfer (LMCT) band at 313 nm, characteristic of the AuCl4– ion, upon the addition of chitosan evidenced the complexation of Au(III) with glucosamine moieties at pH 4. The coordination sphere of Au(III) was determined from the results of XAS experiments in the case of a [GLA]/[Au(III)] ratio equal to 1/4. The Au–Cl and Au–O(N) bond lengths were determined. Finally, preliminary results of gold nanoparticle synthesis by Au(III) reduction under electron beam in the presence of chitosan were presented. The influence of gold speciation on the size of preformed Au(0) clusters was evidenced.

A Comparative Study of Partial Oxidation of Methanol over Zinc Oxide Supported Metallic Catalysts

Au/ZnO, Pd/ZnO and Au–Pd/ZnO catalysts were prepared by PVP-stabilized reduction method by C2H5OH. The catalysts have been used successfully for hydrogen production by partial oxidation of methanol (POM). The influence of Au, Pd and Au–Pd on the performance of supported catalysts for POM has been investigated. The prepared samples were characterized by ICP, XRD, BET, TPR and TPD. The results show that the Au–Pd/ZnO catalyst are more active and exhibit higher hydrogen selectively compared to the Pd/ZnO and Au/ZnO catalyst, the methanol conversion of 99.5% and hydrogen selectivity of 65.6% were obtained at 573 K. The enhanced activity and stability of the bimetallic Au–Pd/ZnO catalyst has been explained in terms of the higher dispersion and basic density, smaller particles of gold and synergetic effect between gold and palladium.

In-plane anisotropic electrical and optical properties of gold-doped rhenium disulphide

Au-doped ReS2 layer crystals were grown by chemical vapour method with iodine as the transport agent. Room temperature Hall effect measurement showed p-type semiconducting character for the doped sample. The elec- trical conductivities parallel and perpendicular to the crystal b-axis were investigated. The near band-edge tem- perature-dependent in-plane anisotropic optical properties were studied by the polarization-dependent photoconduc- tivity measurements, with the incident light beam parallel and perpendicular to the crystal b-axis, in the temperature range from 20 to 300 K. The influence of Au in the mea- sured conductivity anisotropy and photoconductivity spectra of doped ReS2 were analysed and discussed.

High-resolution detection of Au catalyst atoms in Si nanowires

The potential for the metal nanocatalyst to contaminate vapour-liquid-solid grown semiconductor nanowires has been a long-standing concern, because the most common catalyst material, Au, is highly detrimental to the performance of minority carrier electronic devices. We have detected single Au atoms in Si nanowires grown using Au nanocatalyst particles in a vapour-liquid-solid process. Using high-angle annular dark-field scanning transmission electron microscopy, Au atoms were observed in higher numbers than expected from a simple extrapolation of the bulk solubility to the low growth temperature. Direct measurements of the minority carrier diffusion length versus nanowire diameter, however, demonstrate that surface recombination controls minority carrier transport in as-grown n-type nanowires; the influence of Au is negligible. These results advance the quantitative correlation of atomic-scale structure with the properties of nanomaterials and can provide essential guidance to the development of nanowire-based device technologies.

The influence of Au on the adsorption of methylacetoacetate on Ni—a study with medium energy ion scattering and reflection absorption infrared spectroscopy

The hydrogenation of β-ketoesters over chirally modified Ni catalysts is one of the most successful examples of enantioselective heterogeneous catalysis. One of the factors limiting the enantioselectivity of this process is the fact that bare (achiral) Ni sites are active for the racemic hydrogenation reaction. In this work, we investigate the interaction of the simplest β-ketoester, methylacetoacetate, with bimetallic Ni/Au surfaces in order to examine whether the addition of Au to the Ni catalyst has the potential to enhance the enantioselectivity of the catalytic reaction. Using reflection absorption infrared spectroscopy (RAIRS), we probe the molecular conformation of methylacetoacetate on the bimetallic surface as a function of pre-annealing temperature. We show that the presence of Au strongly influences the adsorption of methylacetoacetate which adsorbs predominantly as the enolate. Using medium energy ion scattering (MEIS), we found that once the surface composition of Ni reaches ∼20% or above, the sticking probability of methylacetoacetate increases significantly and methylacetoacetate adsorption results in further segregation of Ni to the surface. The implications for enantioselective heterogeneous catalysis are discussed.

Charge Transfer and Chemical Hardness along a Substitution Path in Metastable Au‐Sb Alloys

AbstractIn the present study the synthesis of metastable alloys of the noble metal Au and the semimetal Sb is realized by using high pressure techniques. The influence of Au on bulk Sb is shown experimentally by stepwise substitution. In addition to the effect of the most electronegative noble metal on Pauling's scale in the binary Au‐Sb phases, some ternary compounds with In, Sn, As, and Te in addition to Au and Sb are discussed. The experiments are planned to obtain a better knowledge on the reasons for building up a simple cubic Sb partial lattice, and their crystallographic results are used to construct model structures for new electronic structure calculations from first principles on the metastable π‐phases. Using the LCAO‐CO ansatz and density‐functional methods, we study total energies, band structures, densities of states and charge transfer properties according to Bader's method by integrating zero flux surfaces. Finally, from electronic band structure analysis, the quantities “chemical potential” μ, and “chemical hardness”, η, are derived according to the original ideas of Pearson and Parr and are applied to solid state problems using special points of the Brillouin zones within a band structure approximation for the first time. The results are shown to support the experimental findings about the substitution path within the system Au‐Sb.

Influence of Au and Pt on the concentration profile of Mn in Si

The influence of diffusion of gold and platinum from the layer deposited on the silicon surface on the concentration profile of 54Mn in the bulk is investigated using the radiochemical technique. The data obtained indicate that the manganese concentration in the bulk of silicon is reduced due to annealing of the samples Si〈54Mn〉 with the gold or platinum layer on the surface.

Influence of Au and Cu overlayers on the magnetic structure of Co films on W(110)

The dependence of the angular distribution of the magnetization in ultrathin epitaxial Co layers upon the thickness of Au and Cu overlayers is studied in situ by spin-polarized low-energy electron microscopy in the thickness range from 0 to 3 monolayers. Only Cu overlayers cause a peak in the coverage dependence of the perpendicular magnetic anisotropy at 1.5 ML coverage. The relation between the nanostructure of the overlayers and the anisotropy is discussed.