The effects of in situ-deposition temperature
and post-deposition annealing on the microstructure of the
sputtered SnO2 thin film are studied. These effects on the
performance of the resulting gas-sensing devices have been
characterized. For in situ-deposition temperature, the film
was deposited on a heated substrate, while for post-deposition
annealing, the film was deposited on an unheated
substrate and then annealed it at various temperatures.
Microstructure changes in SnO2 film were induced at
various temperatures. Both films of in situ heating and
post-annealing evoked only partial crystallization, especially
at low temperatures, and the crystallinity was
enhanced with high temperatures. SEM images confirmed
that the grains and pores of the film changed with the
thermal treatment. In consequence of the post-annealing,
the pores grew wider; however, they grew narrow in the
case of in situ heating. The film annealed at low temperature
yielded high-response device to NO2 gas compared
with that annealed at higher temperature. The sensing
devices fabricated by in situ deposition showed highest
response.