Highly uniform wafer-scale synthesis of<i>α</i>-MoO₃by plasma enhanced chemical vapor deposition

Abstract

Molybdenum oxide (MoO₃) has gained immense attention because of its high electron mobility, wide band gap, and excellent optical and catalytic properties. However, the synthesis of uniform and large-area MoO₃ is challenging. Here, we report the synthesis of wafer-scale α-MoO₃ by plasma oxidation of Mo deposited on Si/SiO₂. Mo was oxidized by O₂ plasma in a plasma enhanced chemical vapor deposition (PECVD) system at 150 °C. It was found that the synthesized α-MoO₃ had a highly uniform crystalline structure. For the as-synthesized α-MoO₃ sensor, we observed a current change when the relative humidity was increased from 11% to 95%. The sensor was exposed to different humidity levels with fast recovery time of about 8 s. Hence this feasibility study shows that MoO₃ synthesized at low temperature can be utilized for gas sensing applications by adopting flexible device technology.