Effect of in-flight annealing and deposition method on gas-sensitive SnOx films made from size-selected nanoparticles

A method which includes synthesis of SnO nanoparticles, size-selection, in-flight oxidation, film formation and post-deposition annealing in oxygen has been investigated. High-temperature in-flight annealing of SnO nanoparticles in the presence of oxygen allowed to assess the effect of this short-time annealing in comparison to post-deposition annealing at lower temperature. This high-temperature annealing was performed in-flight and allowed to keep the crystal size constant, whereas post-deposition high-temperature annealing would have led to crystal growth. Its effect on crystal structure, surface stoichiometry and normalized conductance in ethanol-containing air was investigated. Furthermore, the influence of different particle deposition methods on the crystal phase is shown. Finally, the results indicated that the form of the response transients was markedly different for different gases.