Focusing on the liquid role in the vapour liquid solid growth mechanism
In this work we dive into key questions regarding the wetting of a nanoscale droplet which
provides fundamental understanding of Vapor-Liquid-Solid growth mode of nanowires. This
understanding is important to performreproducible NW fabrication and allow their industrial
implementation. Our method relies on the continuous interplay between experimental efforts
and theoreticalmodeling in order to combine computational prediction power with reality.
In particular the main aspects analysed are the stability of the calalyst-NW system and the
dynamics of nucleation at the nanoscale. These phenomena are of fundamental importance
not only for the synthesis of nanostructures but also in other areas such as colloidal chemistry
and bioengineering. We proceed by focusing on three main aspects of NW preparation: first
stages of NWâ s growth, catalyst-NW system stability and nucleation dynamics. At first we
focus on the preparation of arrays of semiconductor nanowires with the target to optimize
the vertical yield thanks to the engineering of the wetting behavior of the catalytic droplets
at the initial stages of growth. Secondly we investigate the wetting behavior of droplets constrained
on top of nanowires and/or cylindrical pillars. In such conditions, droplet volume and
constraint geometry are the key factors for determining the most stable configuration of the
droplet and thus the direction of further steps of growth. In the last chapters, we analyzemore
exotic nanowires and thus the wetting behavior of droplets is observed on new geometrical
constraints. Beyond dropletâ s morphological investigation, we consider the consequences of
the presence of the liquid phase on the nucleation dynamics, in particular at the triple-phase
line, under the assumption of crystal anisotropy of the nucleating phase and the presence of
stretching capillary forces.
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