摘要
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>x</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>x</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>x</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 S/N > 10 for the potential development of a low-cost plastic/wearable sensor with high sensitivity.