Sol–gel prepared MoO3–WO3 thin-films for O2 gas sensing

Oxygen gas sensing properties of molybdenum trioxide and tungsten trioxide (MoO3–WO3) mixed metal oxide thin-films are investigated. Various MoO3–WO3 ratio thin-film samples are deposited onto silicon (1 0 0) and sapphire substrates via the sol–gel route. SEM analysis showed the presence of MoO3 orthorhombic phase, abating as WO3 dominated the mixed system. MoO3–WO3 sensors exhibited a linear response to O2 concentrations varying from 10 to 10,000 ppm. The MoO3–WO3 film response was stable and reproducible operating at an optimal temperature of 420°C.