Gas sensing properties of PLD made MoO3 films

Pulsed laser deposition (PLD) of MoO3 thin films and their gas sensing properties are reported. As-deposited films were found to be a mixture of sub-oxides. Post-annealing of the films in air at 773 K for 5 h transforms the sub-oxides to MoO3 with diminished intensities of (0 k 0) reflections. The microstructure of the films were investigated by scanning electron microscopy and atomic force microscopy (AFM). Sensors made of thin films (∼1 μm) of MoO3 deposited at 673 K followed by post-annealing in air at 773 K exhibit a high selectivity for ammonia in the temperature range of 508–555 K with fast response (∼15 s) and retrace times (∼300 s).