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Project Topic
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The SIMPLANT project is dedicated to the controlled synthesis of transition metal dichalcogenide
(TMDC) materials by ion implantation. This 24 months duration project brings together 4 academic
laboratories and an industrial one, namely (i) CNRS-Ecole polytechnique from France, (ii) Institute for
Nuclear and Radiation Physics (IKS) and (iii) Laboratory of Solid State Physics and Magnetism (VSM),
both from KU Leuven, Belgium, (iv) Fritz Haber Institute from Germany, as well as (v) Thales Research
& Technology, from France. The project will be coordinated by D. Pribat from CNRS-Ecole
polytechnique. The total requested funding is 873 k€.
The general objective of the project is to develop a large-scale technique for the uniform synthesis of
TMDCs with a controlled number of unit layers (say from 1 to 5), using ion implantation, followed by
an appropriate annealing at high temperature. Essentially 2 approaches will be studied, namely (i)
the implantation of the chalcogen ion into epitaxial thin films of the transition metals and (ii) the coimplantation
of both the chalcogen and metal ions into a neutral substrate, preferably
monocrystalline (sapphire, MgO …), both followed by an annealing sequence in the 650-850 °C range.
Two representative semiconductor TMDCs have been chosen for the project: MoS2 and WS2.
Our preliminary experiments, using 10 nm-thick, small grain polycrystalline Mo films deposited on
oxidized Si substrates and ion implanted with 2.5 x 1015 sulfur atoms/cm2 have demonstrated the
formation of MoS2 when the post-implantation annealing was performed in a sealed quartz ampoule
at 750 °C during 1 hour. However, even though the Raman signal was found uniform over the 1 cm2
area sample, the crystalline orientation of the MoS2 layers was random, so that monocrystalline
metal films and substrates will be needed during the project, in order to induce epitaxial growth of
the TMDC layers upon annealing.
The project is built around 5 workpackages (WPs). WP1 led by IKS deals with substrate preparation
(including transition metal epitaxial deposition by VSM and IKS) and ion implantation (IKS). WP2 led
by FHI is dedicated to the study of post-implantation annealing by in situ observations using x-ray
photoelectron spectroscopy (XPS) at FHI as well as in situ high resolution transmission electron
microscopy (HR-TEM) at CNRS. WP3 led by CNRS is devoted to the ex situ physical characterizations
of the synthesized TMDC materials, using Raman spectroscopy and photoluminescence at TRT, XPS at
FHI (with different photon energies to measure depth profiles), HR-TEM at CNRS, scanning tunnelling
microscopy and spectroscopy (STM and STS) at VSM. Moreover, angle resolved photoelectron
spectroscopy (ARPES) will be subcontracted to the ANTARES group of the SOLEIL synchrotron in
France. WP4 led by TRT corresponds to the electronic (carrier mobility) and optoelectronic
characterizations by TRT and CNRS of field-effect transistor structures fabricated by TRT. WP5 led by
CNRS is dedicated to the project management, the exploitation of the results and the partnership
with the Graphene Flagship (CNRS-TRT).
Because we have already made preliminary experiments showing the feasibility of the process that
we propose, the risk should be low. The anticipated outcome of the project is a high throughput,
uniform and large scale method for the synthesis of TMDCs with their thickness controlled between 1
and 5 unit layers.
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