F. Vaurette | Searcharxiv

arXiv2016

Geometric and chemical components of the giant piezoresistance in silicon nanowires

A wide variety of apparently contradictory piezoresistance (PZR) behaviors have been reported in p-type silicon nanowires (SiNW), from the usual positive bulk effect to anomalous (negative) PZR and giant PZR. The origin of such a range of diverse phenomena is unclear, and consequently so too is the importance of a number of parameters including SiNW type (top down or bottom up), stress concentration, electrostatic field effects, or surface chemistry. Here we observe all these PZR behaviors in a single set of nominally p-type, $\langle 110 \rangle$ oriented, top-down SiNWs at uniaxial tensile stresses up to 0.5 MPa. Longitudinal $π$-coefficients varying from $-800\times10^{-11}$ Pa$^{-1}$ to $3000\times10^{-11}$ Pa$^{-1}$ are measured. Micro-Raman spectroscopy on chemically treated nanowires reveals that stress concentration is the principal source of giant PZR. The sign and an excess PZR similar in magnitude to the bulk effect are related to the chemical treatment of the SiNW.

cond-mat.mes-hall↗

arXiv2011

Large array of sub-10 nm single-grain Au nanodots for use in nanotechnology

A uniform array of single-grain Au nanodots, as small as 5-8 nm, can be formed on silicon using e-beam lithography. The as-fabricated nanodots are amorphous, and thermal annealing converts them to pure Au single crystals covered with a thin SiO2 layer. These findings are based on physical measurements, such as atomic force microscopy (AFM), atomic resolution scanning transmission electron microscopy, and chemical techniques using energy dispersive x-ray spectroscopy. A self-assembled organic monolayer is grafted on the nanodots and characterized chemically with nanometric lateral resolution. We use the extended uniform array of nanodots as a new test-bed for molecular electronics devices.

cond-mat.mes-hall↗