Pt-, Pd-, and Zr-doped SnO2 thin films and dopant-free VOx films were fabri
cated by planar magnetron sputtering. Tests for sensitivity to SO2 for all
samples were conducted at 180 degreesC, and the sensitivities were investig
ated ex situ with photometric and ellipsometric methods at room temperature
. It was found that the optical sensitivities as well as the sensitive wave
length region for SnO2 films could be tuned by doping. The Pd-doped SnO2 fi
lms had good sensitivity in the visible range, and the Zr-doped in the near
IR. The dominant sensitive wavelength region for VOx films fell into the v
isible range, and the ratio of the sensitivity in the visible to that in th
e near IR increased with O-2/Ar in the depositing atmosphere. (C) 2001 soci
ety of Photo-Optical instrumentation Engineers .