Semiconductor gas sensor based on tin oxide nanorods prepared by plasma-enhanced chemical vapor deposition with postplasma treatment

${\mathrm{SnO}}_2$ thin films were deposited by radio-frequency inductively coupled plasma-enhanced chemical vapor deposition. Postplasma treatments were used to modify the microstructure of the as-deposited ${\mathrm{SnO}}_2$ thin films. Uniform nanorods with dimension of $\varnothing 7\times 100\mathrm{nm}$ were observed in the plasma-treated films. After plasma treatments, the optimal operating temperature of the plasma-treated ${\mathrm{SnO}}_2$ thin films decreased by 80 °C, while the gas sensitivity increased eightfold. The enhanced gas sensing properties of the plasma-treated ${\mathrm{SnO}}_2$ thin film were believed to result from the large surface-to-volume ratio of the nanorods’ tiny grain size in the scale comparable to the space-charge length and its unique microstructure of ${\mathrm{SnO}}_2$ nanorods rooted in ${\mathrm{SnO}}_2$ thin films.