Plasma Surface Modification and Gas Sensing Properties of SnO2 Thin Films Prepared by Plasma Enhanced Chemical Vapor Deposition

SnO₂ thin films were deposited by RF inductively coupled plasma enhanced chemical vapor deposition (PECVD) using dibutyltin diacetate as the precursor. The as-deposited SnO₂ thin films were granular with a grain size of 20 nm. The as-deposited thin films were post-treated in the plasma to modify the films surface morphologies. After plasma treatment, uniform nanorods in the size of Phi7 times 200 nm were observed in the plasma-treated SnO₂ thin films. The gas sensing properties of the as-deposited and plasma-treated SnO₂ thin films were comparatively studied. The plasma-treated sample with nanorods showed much higher sensitivity, faster response and shorter recovery time compared to the as-deposited sample with nanograins. The tremendous improvement of the gas sensing properties of the plasma-treated sample was believed to be attributed to the intrinsically small grain size comparable to the space-charge length and high surface-to-volume ratios associated with the nanorods