1. Theory of Polymer Properties
Prof. Lee Jae Won
Nguyen Hong Dang (Master’s degree)
ID: 202228042
Control and Enhance the 1D structure of TMD
MoS2 by Chemical Vapour Deposition method
2. I. Introduction & Experimental:
• Atomically transition-metal dichalcogenides (TMDs) have drawn much interest for their
promising applications in electronics, optoelectronic, valleytronic and sensing fields.
• Molybdenum disulfide (MoS2) is a two-dimensional (2D) layered material of the
transition-metal dichalcogenides (TMDs) family.
• In particular, the recent demonstration of superconductivity in MoS2 monolayer suggests
that realizing nanowire geomertry for MoS2 may be important to investigate the potential
in one-dimensional topological superconductors.
• However, it is a challenging method to control 1D structure in MoS2 because of the highly
sensitivity and difficult to control all factors such as heating rate, pressure and air flow.
• In this work, we demonstrate a large yield, low temperature synthesis of MoS2 nanowires,
an approximate one-dimensional system, by converting MoO3 nanowires via sulfurization.
3. I. Introduction & Experimental:
QUARTZTUBE
QUARTZTUBE
Au
Si
H2
• Synthesis MoO3 nanowire by CVD method:
• In this study, we develop a chemical
vapour deposition (CVD) process, with
Silicon substrate sputtered by Au thin
film (about 2-3nm) as a catalyst for the
growth at a temperature above 600 ◦C, to
grow high-quality 1D ultrathin MoS2
nanowires a few nanometers in thickness.
• MoO3 powder was placed at the
downstream of a 1 in. tube furnace with
[100]Si substrate located 11cm
downstream. After purging with Ar
multiple times, the system was pumped
down to 100 mTorr, then H2 was flowed
at 20sccm and bringing the furnace
pressure up to ~3 Torr. The furnace was
heated to 600 ◦C over the course of 15
min and held at temperature for 5-10 min
before naturally cooled down to room
temperature.
MoO3
4. I. Introduction & Experimental:
• MoS2 nanowire conversion:
• MoS2 nanowires were grown by
converting MoO3 nanowires. Grown
MoO3 nanowires were placed just
downstream of S powder in the center of
a 2.5 in. two-zone furnace. The two-zone
furnace was used to ensure a wide region
of uniform temperature. H2 was flowed at
100 sccm at atmospheric pressure. After
purge time more than 20 min, the two
zones were heated in unison to 500 ◦C in
15 min and held there for 10 min, then
allowed to naturally cool to room
temperature.
• H2 gas is employed to first form the more
reactive intermediate product H2S, which
reduces the MoO3 nanowires to form
MoS2 nanowires.
S Si
MoO3 nanowires
H2S
H2 flow
5. II. Result and Discussion:
• SEM result shows that the nanowires
morphology deposited on the surface of
the Si substrate.
6. II. Result and Discussion:
MoS2
MoS2
MoS2
• XRD result shows that the components
which were deposited on the surface of
the Si substrate.
7. II. Result and Discussion:
• Issues in controlling MoS2 1D morphology:
• MoS2 nanowires were highly sensitivity
and difficulty to control while using CVD
method (the method that frequently use
for the growth of thin film, 2D nano
structures).
• Numerous factors effect on the growth of
1D structures, especially MoS2 nanowires
in this study such as: the flow rate of the
gas used, the heating speed, pressure,
etc… And these factors are hard to
control at the same time, if any factor is
changed, it will lead to the different
result.
• This figure shows MoS2 nano particles,
when the pressure was changed.
8. II. Result and Discussion:
• Solution:
• We decided to sputter a thin film of Au on the Si substrate as a catalyst for the growth.
• Combined multiple gases used (Ar & H2, or N2,…) during the growth.
• For the further plan we deciding to use more catalysts to enhance the growth and developing
the quality of 1D structures.
