1 research outputs found
Wafer-Scale Growth of WSe<sub>2</sub> Monolayers Toward Phase-Engineered Hybrid WO<sub><i>x</i></sub>/WSe<sub>2</sub> Films with Sub-ppb NO<sub><i>x</i></sub> Gas Sensing by a Low-Temperature Plasma-Assisted Selenization Process
An
inductively coupled plasma (ICP) process was used to synthesize
transition metal dichalcogenides (TMDs) through a plasma-assisted
selenization process of metal oxide (MO<sub><i>x</i></sub>) at a temperature as low as 250 °C. In comparison with other
CVD processes, the use of ICP facilitates the decomposition of the
precursors at low temperatures. Therefore, the temperature required
for the formation of TMDs can be drastically reduced. WSe<sub>2</sub> was chosen as a model material system due to its technological importance
as a p-type inorganic semiconductor with an excellent hole mobility.
Large-area synthesis of WSe<sub>2</sub> on polyimide (30 × 40
cm<sup>2</sup>) flexible substrates and 8 in. silicon wafers with
good uniformity was demonstrated at the formation temperature of 250
°C confirmed by Raman and X-ray photoelectron (XPS) spectroscopy.
Furthermore, by controlling different H<sub>2</sub>/N<sub>2</sub> ratios,
hybrid WO<sub><i>x</i></sub>/WSe<sub>2</sub> films can be
formed at the formation temperature of 250 °C confirmed by TEM
and XPS. Remarkably, hybrid films composed of partially reduced WO<sub><i>x</i></sub> and small domains of WSe<sub>2</sub> with
a thickness of ∼5 nm show a sensitivity of 20% at 25 ppb at
room temperature, and an estimated detection limit of 0.3 ppb with
a <i>S</i>/<i>N</i> > 10 for the potential
development
of a low-cost plastic/wearable sensor with high sensitivity