Improvement of ozone detection with GLAD WO3 films.

Tungsten oxide WO 3 thin films were prepared by dc reactive magnetron sputtering. The GLancing Angle Deposition (GLAD) technique was implemented to transform the typical dense microstructure into an inclined columnar and porous architecture. The incident angle α of the sputtered particles was 0° and 70° leading to a column tilt angle β of 0° and 40°, respectively. Conventional and inclined WO 3 films were sputter deposited on a commercial hotplate system. Ozone gas was periodically injected from 0 to 220 ppb and the variation of electrical conductance of the system was measured vs. time at 250 °C. The conventional WO 3 films exhibited a significant change of electrical conductance as a function of the ozone injection. GLAD WO 3 films with a columnar angle β =40° were even more sensitive to the ozone pulses and the speed of response or recovery was significantly enhanced. This ozone detection improvement was mainly attributed to the more porous structure of WO 3 films produced by the GLAD method. [ABSTRACT FROM AUTHOR]