78 research outputs found
Very low effective Schottky barrier height for erbium disilicide contacts on n-Si through arsenic segregation
The segregation of As+ ions implanted into thin Er films deposited on n-Si
substrates is studied after ErSi2-x formation. The same lowering of the
effective Schottky barrier height (SBH) below 0.12 eV is obtained at moderate
annealing temperatures, regardless of the redistribution of As dopants at the
ErSi2-x/Si interface. On the other hand, if the implanted dose is slightly
enhanced, the annealing temperature required to reach sub-0.12-eV effective SBH
can be further reduced. This process enables the formation of very low
effective SBH ErSi2-x/n-Si contacts with a low thermal budget
Toward an experimental proof of superhydrophobicity enhanced by quantum fluctuations freezing on a broadband-absorber metamaterial
Previous theoretical works suggested that superhydrophobicity could be
enhanced through partial inhibition of the quantum vacuum modes at the surface
of a broadband-absorber metamaterial which acts in the extreme ultraviolet
frequency domain. This effect would then compete with the classical
Cassie-Baxter interpretation of superhydrophobicity. In this article, we first
theoretically establish the expected phenomenological features related to such
a kind of "quantum" superhydrophobicity. Then, relying on this theoretical
framework, we experimentally study patterned silicon surfaces on which
organosilane molecules were grafted, all the coated surfaces having similar
characteristic pattern sizes but different profiles. Some of these surfaces can
indeed freeze quantum photon modes while others cannot. While the latter ones
allow hydrophobicity, only the former ones allow for superhydrophobicity. We
believe these results lay the groundwork for further complete assessment of
superhydrophobicity induced by quantum fluctuations freezing.Comment: 10 pages, 5 figures, final version, accepted for publication in
Journal of Applied Physic
Schottky barrier lowering with the formation of crystalline Er silicide on n-Si upon thermal annealing
The evolution of the Schottky barrier height (SBH) of Er silicide contacts to
n-Si is investigated as a function of the annealing temperature. The SBH is
found to drop substantially from 0.43 eV for the as-deposited sample to reach
0.28 eV, its lowest value, at 450 C. By x-ray diffraction, high resolution
transmission electron microscopy, and x-ray photoelectron spectroscopy, the
decrease in the SBH is shown to be associated with the progressive formation of
crystalline ErSi2-x
Adaptive Haar wavelets for the angular discretisation of spectral wave models
A new framework for applying anisotropic angular adaptivity in spectral wave modelling is presented. The angular dimension of the action balance equation is discretised with the use of Haar wavelets, hierarchical piecewise-constant basis functions with compact support, and an adaptive methodology for anisotropically adjusting the resolution of the angular mesh is proposed. This work allows a reduction of computational effort in spectral wave modelling, through a reduction in the degrees of freedom required for a given accuracy, with an automated procedure and minimal cost
Enhanced LightâMatter Interactions in Graphene-Covered Gold Nanovoid Arrays
The combination of graphene with noble-metal nanostructures is currently
being explored for strong light-graphene interaction enhanced by plasmons. We
introduce a novel hybrid graphene-metal system for studying light-matter
interactions with gold-void nanostructures exhibiting resonances in the visible
range. Strong coupling of graphene layers to the plasmon modes of the nanovoid
arrays results in significant frequency shifts of the underlying plasmon
resonances, enabling more than 30% absolute light absorption in a single layer
of graphene and up to 700-fold enhancement of the Raman response of the
graphene. These new perspectives enable us to verify the presence of graphene
on gold-void arrays and the enhancement even allows us to accurately quantify
the number of layers. Experimental observations are further supported by
numerical simulations and perturbation-theory analysis. The graphene gold-void
platform is beneficial for sensing of molecules and placing R6G dye molecules
on top of the graphene, we observe a strong enhancement of the R6G Raman
fingerprints. These results pave the way toward advanced substrates for
surface-enhanced Raman scattering (SERS) with potential for unambiguous
single-molecule detection on the atomically well-defined layer of graphene.Comment: 17 pages including 5 figure
Integrin ÎČ3 Crosstalk with VEGFR Accommodating Tyrosine Phosphorylation as a Regulatory Switch
Integrins mediate cell adhesion, migration, and survival by connecting intracellular machinery with the surrounding extracellular matrix. Previous studies demonstrated the importance of the interaction between ÎČ3 integrin and VEGF type 2 receptor (VEGFR2) in VEGF-induced angiogenesis. Here we present in vitro evidence of the direct association between the cytoplasmic tails (CTs) of ÎČ3 and VEGFR2. Specifically, the membrane-proximal motif around 801YLSI in VEGFR2 mediates its binding to non-phosphorylated ÎČ3CT, accommodating an α-helical turn in integrin bound conformation. We also show that Y747 phosphorylation of ÎČ3 enhances the above interaction. To demonstrate the importance of ÎČ3 phosphorylation in endothelial cell functions, we synthesized ÎČ3CT-mimicking Y747 phosphorylated and unphosphorylated membrane permeable peptides. We show that a peptide containing phospho-Y747 but not F747 significantly inhibits VEGF-induced signaling and angiogenesis. Moreover, phospho-Y747 peptide exhibits inhibitory effect only in WT but not in ÎČ3 integrin knock-out or ÎČ3 integrin knock-in cells expressing ÎČ3 with two tyrosines substituted for phenylalanines, demonstrating its specificity. Importantly, these peptides have no effect on fibroblast growth factor receptor signaling. Collectively these data provide novel mechanistic insights into phosphorylation dependent cross-talk between integrin and VEGFR2
A dataset of acoustic measurements from soundscapes collected worldwide during the COVID-19 pandemic
Political responses to the COVID-19 pandemic led to changes in city soundscapes around the globe. From March to October 2020, a consortium of 261 contributors from 35 countries brought together by the Silent Cities project built a unique soundscape recordings collection to report on local acoustic changes in urban areas. We present this collection here, along with metadata including observational descriptions of the local areas from the contributors, open-source environmental data, open-source confinement levels and calculation of acoustic descriptors. We performed a technical validation of the dataset using statistical models run on a subset of manually annotated soundscapes. Results confirmed the large-scale usability of ecoacoustic indices and automatic sound event recognition in the Silent Cities soundscape collection. We expect this dataset to be useful for research in the multidisciplinary field of environmental sciences
- âŠ