Preparation and characterization of proton implanted indium tin oxide selective gas sensors

Indium tin oxide (SnO2) thin films were deposited onto glass substrates by sputtering technique. The as-sputtered indium tin oxide sensing films show negligible sensitivities of around 1% in response to different gases. In order to improve the sensitivity of the gas sensors the as-sputtered and air-annealed samples were submitted to proton implantation with energy of 15 keV using various doses ranging from 1×1015 to 1×1017 cm−2. The characterization of an improved gas sensor with better selectivity is reported. An increase in implantation dose results in enhancement of the sensitivity of the gas sensors up to more than 8%. Encouraging results show that the pre-radiation annealed sensor exhibits a high response to carbon monoxide and low responses to hydrogen and methanol. The sensing films were characterized by scanning electron microscopy (SEM) to investigate their morphology and pore structures. The micrographs give evidence of different porosity for sensing films implanted with different doses.