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Register a new userAssociation Between Gold Grain Orientation And Its Periodic Steps Formed At The Gold/Substrate Interface
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Nanoscale step structures have attracted recent interest owing to their importance in both fundamental and applied research, for example in adsorption, in catalysis, and in directing nanowire growth. Here, we used a template-stripping method to obtain vicinal-like surface structures on grains of polycrystalline gold and investigated the effect of annealing temperature on the formation of these surfaces.
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We experimentally investigate charge transport through the interface between a gold electrode and a black phosphorus single crystal. The experimental $dI/dV(V)$ curves are characterized by well developed zero-bias conductance peak and two strongly different branches. We find that two branches of asymmetric $dI/dV(V)$ curves correspond to different band gap limits, which is consistent with the theoretically predicted band gap reconstruction at the surface of black phosphorus under electric field. This conclusion is confirmed by experimental comparison with the symmetric curves for narrow-gap (WTe$_2$) and wide-gap (GaSe) metal-semiconductor structures. In addition, we demonstrate p-type dopants redistribution at high bias voltages of different sign, which opens a way to use the interface structures with black phosphorus in resistive memory applications.
In this paper, we have tried to find out the origin of magnetism in Gold nanoparticles (Au- NPs). We observe that upon incorporating Gold nanoparticles (Au-NPs) in Fe3O4 nanoparticle medium the net magnetisation increases compared to the pure Fe3O4 nanoparticle medium. This increase of magnetization can be attributed to the large orbital magnetic moment formation at the Au/magnetic particle interface indicating that magnetism observed in Au-NPs is an interfacial effect. This interfacial effect has been supported by the observation of sudden transition from positive saturated magnetisation to a negative diamagnetic contribution as a function of magnetic field on citrate coated gold Au-NPs.
Gold-mediated exfoliation of MoS2 has attracted considerable interest in the recent years. A strong interaction between MoS2 and Au facilitates preferential production of centimeter-sized monolayer MoS2 with near-unity yield and provides a heterostructure system noteworthy from a fundamental standpoint. However, little is known about the detailed nature of the MoS2-Au interaction and its evolution with the MoS2 thickness. Here, we identify specific vibrational and binding energy fingerprints of such strong interaction using Raman and X-ray photoelectron spectroscopy, which indicate substantial strain and charge-transfer in monolayer MoS2. Near-field tip-enhanced Raman spectroscopy reveals heterogeneity of the MoS2-Au interaction at the nanoscale, reflecting the spatial non-conformity between the two materials. Far-field micro-Raman spectroscopy shows that this interaction is strongly affected by the roughness and cleanliness of the underlying Au. Our results elucidate the nature of the strong MoS2-Au interaction and provide guidance for strain and charge doping engineering of MoS2.
The electronic Seebeck response in a conductor involves the energy-dependent mean free path of the charge carriers and is affected by crystal structure, scattering from boundaries and defects, and strain. Previous photothermoelectric (PTE) studies have suggested that the thermoelectric properties of polycrystalline metal nanowires are related to grain structure, though direct evidence linking crystal microstructure to the PTE response is difficult to elucidate. Here, we show that room temperature scanning PTE measurements are sensitive probes that can detect subtle changes in the local Seebeck coefficient of gold tied to the underlying defects and strain that mediate crystal deformation. This connection is revealed through a combination of scanning PTE and electron microscopy measurements of single crystal and bicrystal gold microscale devices. Unexpectedly, the photovoltage maps strongly correlate with gradually varying crystallographic misorientations detected by electron backscatter diffraction. The effects of individual grain boundaries and differing grain orientations on the PTE signal are minimal. This scanning PTE technique shows promise for identifying minor structural distortions in nanoscale materials and devices.
In this paper, we report our study on gold (Au) films with different thicknesses deposited on single layer graphene (SLG) as surface enhanced Raman scattering (SERS) substrates for the characterization of rhodamine (R6G) molecules. We find that an Au film with a thickness of ~7 nm deposited on SLG is an ideal substrate for SERS, giving the strongest Raman signals for the molecules and the weakest photoluminescence (PL) background. While Au films effectively enhance both the Raman and PL signals of molecules, SLG effectively quenches the PL signals from the Au film and molecules. The former is due to the electromagnetic mechanism involved while the latter is due to the strong resonance energy transfer from Au to SLG. Hence, the combination of Au films and SLG can be widely used in the characterization of low concentration molecules with relatively weak Raman signals.
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