Analysis of Nano-Structured ${\rm In}_{2}{\rm O}_{3}$ Thin Film ${\rm NO}_{\rm x}$ Sensor by AC Impedance Spectroscopy

Nano-structured In
₂
O
₃
thin film was made using a pulsed laser deposition technique. The surface topography and structural properties of the thin film were characterized by atomic force microscopy and X-ray diffraction, respectively. Complex impedance spectroscopy of In
₂
O
₃
thin film gas sensor was investigated from 275 °C to 425 °C when exposed into clean air and air containing a trace level of NOx. Significant NOx sensing characteristics of thin film were observed at 325 °C by ac impedance spectroscopic analysis. The resistance and capacitance of indium oxide film increased when exposed into the trace level of NOx. A mechanism for this increase of resistance and capacitance is proposed.