Synthesis and enhanced room temperature ammonia gas–sensing properties of In-doped MoO3 thin films prepared via nebulizer spray pyrolysis technique

For the application of room temperature ammonia gas sensing, different concentrations of 1, 2, 3, 4, and 5% of indium (In)-doped MoO 3 thin films are synthesized using the nebulizer spray pyrolysis method. The various properties such as microstructure, morphology, and optical properties are characterized using several techniques, namely X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), UV–Vis spectroscopy, photoluminescence (PL) spectroscopy. The existence of orthorhombic crystal structure of MoO 3 is confirmed through XRD analysis with variation in crystallinity with the incorporation of In dopants into MoO3. FESEM results showed the nanofibrous reticulated chained morphology for the as-fabricated MoO 3 film, and the average diameter increased for the In-doped MoO 3 films. The UV–Vis and PL studies revealed that the prepared 3% In-doped MoO 3 film has lower transmittance, lower bandgap of 2.94 eV, and higher oxygen vacancies. Moreover, a maximum gas response of 18,900 for 3% In-doped MoO 3 film was achieved while establishing the gas-sensing properties of the fabricated sensors for NH 3 detection at ambient temperature. Faster response and recovery times of 42 and 8 s, respectively are seen at 3% In-doped MoO 3 film sensor compared to the other fabricated sensors, which may be the useful candidate for sensitive application like MoO 3 gas sensors.