Activity Report 2010 - CNRS

Growth, patterning, defects
& structure of nano-objects.
The elaboration and characterisation of
nano-objects is of primary importance in
nanosciences and requires a mastering of
complex experimental methods.
Numerical simulation is of great help in
understanding the details of the physical
mechanism involved in elaboration
procedure and in interpreting the output
of methods used to analyze the structure
of these objects.
In this context the Nanosciences
Foundation supports so far three Chairs
of Excellence and one PhD student.
Chair of Excellence 2009: Normand
MOUSSEAU
Coordinator: Pascal POCHET
(INAC/SP2M)
This project started in early 2010. It aims
at coupling a kinetic method (k-ART)
developed by Pr MOUSSEAU and the abinitio
code BigDFT developed initially at
INAC. The new methodology will then be
coupled to study the growth of three
types of nanostructures: SiGe quantum
dots, Si nanowires and graphene on SiC.
The first tests of the new methodology
have already been done on the simpler
system consisting of a fullerene C20.
The goal of this project is therefore to
benefit from the expertise of Pr Graves in
the field of MDS applied to plasmasurface
interactions to assist the fast
development of etching processes of
graphene layers.
“Fil de l’eau” PhD student 2008: Arpan
Krishna DEB
Thesis Director: Thierry DEUTSCH and
Damien CALISTE (INAC/SP2M).
This thesis deals with cluster approach to
simulate defects in Si or Ge. Indeed
working with charged periodic systems is
a bit complicated as it involves the long
range Coulomb forces and it is impossible
to negate the interaction between the
images created due to the periodicity in
the simulation. A very common approach
is to add a neutralizing background
charge. But even this trick does not
completely eliminate the spurious
interaction of the image charges. The
cluster approach clearly avoids these
difficulties and open new possibilities to
treat these defects.
SCIENTIFIC REPORT
Chair of Excellence 2010: David GRAVES
Coordinator: Gilles CUNGE (LTM).
The Chair of Excellence of Pr GRAVES
(University of California at Berkeley) will
deal with Nanometer Scale Control of
Graphene Processing with Innovative
Plasma Technology (NSCGP). This project
aims to advance nanometer-scale control
of graphene processing using advanced,
innovative plasma technology. In order to
exploit the extraordinary power of plasma
for large area, smooth and damage-free
graphene film growth and patterning, it
will be necessary to take a leap in plasma
technology.
LTM is currently investing such a new
technology: pulsed plasmas. However,
the interactions between reactive
plasmas and surfaces are so complex
that the efficient development of
processes for new materials requires
numerical simulations.
For 20 years, Molecular Dynamic
Simulations (MDS) have proved to be
powerful for this purpose, but this
expertise does not exist locally.
Fig. 5: Cluster of Si used for the simulation of
a defect. Left: cluster with no defect inside.
Right: cluster with one vacancy
.
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