Molecular beam epitaxial growth of multilayer 2D-boron nitride on Ni substrates from borazine and plasma-activated nitrogen.

2D boron nitride (2D-BN) was synthesized by gas-source molecular beam epitaxy on polycrystalline and monocrystalline Ni substrates using gaseous borazine and active nitrogen generated by a remote plasma source. The excess of nitrogen atoms allows to overcome the thickness self-limitation active on Ni when using borazine alone. The nucleation density and the shape of the 2D-BN domains are clearly related to the Ni substrate preparation and to the growth parameters.

Surface modification of carbon dots with tetraalkylammonium moieties for fine tuning their antibacterial activity.

The widespread of bacterial infections including biofilms drives the never-ending quest for new antimicrobial agents. Among the great variety of nanomaterials, carbon dots (CDs) are the most promising antibacterial material, but still require the adjustment of their surface properties for enhanced activity. In this contribution, we report a facile functionalization method of carbon dots (CDs) by tetraalkylammonium moieties using diazonium chemistry to improve their antibacterial activity against Gram-positive and Gram-negative bacteria.

Transport Properties of Methyl-Terminated Germanane Microcrystallites.

Germanane is a two-dimensional material consisting of stacks of atomically thin germanium sheets. It's easy and low-cost synthesis holds promise for the development of atomic-scale devices. However, to become an electronic-grade material, high-quality layered crystals with good chemical purity and stability are needed.

Van Hove Singularities and Trap States in Two-Dimensional CdSe Nanoplatelets.

Semiconductor nanoplatelets, which offer a compelling combination of the flatness of two-dimensional semiconductors and the inherent richness brought about by colloidal nanostructure synthesis, form an ideal and general testbed to investigate fundamental physical effects related to the dimensionality of semiconductors. With low temperature scanning tunnelling spectroscopy and tight binding calculations, we investigate the conduction band density of states of individual CdSe nanoplatelets. We find an occurrence of peaks instead of the typical steplike function associated with a quantum well, that rule out a free in-plane electron motion, in agreement with the theoretical density of states.

Trap-Free Heterostructure of PbS Nanoplatelets on InP(001) by Chemical Epitaxy.

Semiconductor nanocrystalline heterostructures can be produced by the immersion of semiconductor substrates into an aqueous precursor solution, but this approach usually leads to a high density of interfacial traps. In this work, we study the effect of a chemical passivation of the substrate prior to the nanocrystalline growth. PbS nanoplatelets grown on sulfur-treated InP (001) surfaces at temperatures as low as 95 °C exhibit abrupt crystalline interfaces that allow a direct and reproducible electron transfer to the InP substrate through the nanometer-thick nanoplatelets with scanning tunnelling spectroscopy.

Tunneling mechanism and contact mechanics of colloidal nanoparticle assemblies.

Nanoparticle assemblies with thiol-terminated alkyl chains are studied by conducting atomic force microscopy (c-AFM) regarding their use as strain gauges for touch-sensitive panels. Current-force spectroscopy is used as a characterization tool complementary to the macroscopic setup since it allows a bias to be applied to a limited number of junctions, overcoming the Coulomb blockade energy and focusing on the contact electromechanics and the transport mechanism across the ligand. First, transition voltage spectroscopy is applied with varying force to target the underlying tunneling mechanism by observing whether the transition between the ohmic and exponential current-voltage behavior is force-dependent.

Noise performance of frequency modulation Kelvin force microscopy.

Noise performance of a phase-locked loop (PLL) based frequency modulation Kelvin force microscope (FM-KFM) is assessed. Noise propagation is modeled step by step throughout the setup using both exact closed loop noise gains and an approximation known as "noise gain" from operational amplifier (OpAmp) design that offers the advantage of decoupling the noise performance study from considerations of stability and ideal loop response. The bandwidth can be chosen depending on how much noise is acceptable and it is shown that stability is not an issue up to a limit that will be discussed.

Chemical functionalization of electrodes for detection of gaseous nerve agents with carbon nanotube field-effect transistors.

An innovative sensor for the detection of nerve agents in the gas phase based on a carbon nanotube field-effect transistor was developed. A high sensitivity to organophosphorus gases was obtained by modifying gold electrodes with specific tailor-made self-assembled monolayers.

High on-off conductance switching ratio in optically-driven self-assembled conjugated molecular systems.

A new azobenzene-thiophene molecular switch is designed, synthesized, and used to form self-assembled monolayers (SAM) on gold. An "on/off" conductance ratio up to 7 x 10(3) (with an average value of 1.5 x 10(3)) is reported.