Investigation of MoO3-WO3 thin film microstructure for gas sensing applications

MoO3-WO3 thin films have been fabricated via the sol-gel method. FESEM, TEM, RBS and SIMS analysis techniques have been employed to analyse the films and material properties for use as gas sensors to detect CO and NO2. FESEM shows the film made up of segregated MoO3 crystals. TEM highlights the nano-sized grains sructure and crystallinity. RBS analysis confirmed the films are stoichimetric and that the Mo component of the system decreases as the annealing temperature is increased. SIMS illustrates the interesting elemental depth profiles of the films. The films were exposed to CO and NO2, MoO3-WO3 shows better NO2 sensitivity and selectivity compared to its single metal oxide constituents.