Lj. Legore et al., THE OPTIMIZATION OF A TUNGSTEN TRIOXIDE FILM FOR APPLICATION IN A SURFACE-ACOUSTIC-WAVE GAS SENSOR, Sensors and actuators. B, Chemical, 35(1-3), 1996, pp. 164-169
Tungsten trioxide (WO3) thin films were r.f. magnetron sputtered onto
quartz substrates in various argon/oxygen (Ar/O-2) atmospheres at vari
ous deposition rates and temperatures. The electrical conductivity of
the WO3 films was monitored as they were subjected to annealing cycles
of successively higher temperatures with gas testing performed after
each cycle. This work demonstrates that the electrical conductivity of
the WO3 films is a function of deposition parameters such as argon/ox
ygen ratio, deposition rate and substrate temperature and annealing co
nditions. Furthermore, it is shown that by a judicious choice of depos
ition parameters and annealing conditions, WO3 films whose electrical
conductivity falls within the optimum range of operation for a surface
acoustic wave (SAW) gas sensor may be produced.