In this work, MoO3 was thermally evaporated onto gold interdigital fingers on quartz substrates and characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The deposited MoO3 consist of stratified long rectangles (average length of 50 µm width of 5 µm and thickness of 500 nm) which are predominantly orthorhombic (α-MoO3). Each of these plates was composed of many nano-thick layers (average ~30 nm) placed by Van der Waals forces on top of each other forming lamellar patterns. The devices were used as sensors and exhibited considerable change in surface conductivity when exposed to NO2 and H2 gases at elevated temperature of 225 °C. The structural and gas-sensing properties of thermally evaporated MoO3 thin films were investigated.

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