Sputter deposited ZnO porous films for sensing applications

Nanoporous ZnO films are fabricated using a two step approach: sputter deposition of porous Zn followed by an ex-situ annealing in an oxygen flow at 400°C. The created structures have a porosity of 34% enabling use in surface-based absorption sensors. The films are used in a resistance-based sensor allowing easy discrimination between liquid methanol and ethanol by resistance measurements and also in a transmission-based sensor to detect NO 2 , NH 3 and H 2 gases in concentration as low as 500 ppm.