Highly sensitive MOSFET gas sensors with porous Pt-SnOx gate electrode for CO gas sensing applications

Novel gas sensing devices based on a porous Pt-SnO_x metal-oxide-semiconductor field-effect transistor (MOSFET) for carbon monoxide (CO) gas sensing have been fabricated for the first time. The structure integrates the catalytic properties of porous Pt as the thin catalyst layer and the gas sensing properties of SnO_x as the gas adsorptive oxide with surface-sensitive MOSFETs. The threshold voltage decreased rapidly with time when the device was exposed to CO gas. It was possible to detect 54 ppm of CO gas with a response time of <1 min at a device operating temperature of 27°C. A model is proposed to explain the operation. The device detection mechanism of this device presented here corresponds well with the experimental data