Solvent Sensing for Extreme Environments

In this paper, we report for the first time the sensitivity and selectivity of a Pt/TiO
₂
/SiO
₂
/4H-SiC MOS capacitor to a number of industrially relevant organic solvents. The shift in the capacitance - voltage characteristics has been found to be uniquely influenced by the solvent, allowing the specific solvent to be determined. These silicon carbide-based sensor structures have previously been optimised for hydrogen gas detection at elevated temperatures. The presence of solvent vapor induces a rapidly detectable change in the capacitance of the sensor at the flatband voltage. A statistically meaningful relationship between the dipole moment of the solvent and the magnitude of the capacitance shift is observed. We describe the observed shift in terms of the diploe moment changing the charged state of defects, resulting in the formation of a charge dipole similar to the gas sensing mechanism.