Interaction of porous Pt-SnO2 gate metal-oxide-semiconductor field-effect transistor device with CO

Novel gas-sensing devices based on a porous Pt-SnO2 metal-oxide-semiconduct or field-effect transistor (MOSFET) for carbon monoxide (CO) gas sensing ha ve been fabricated. The structure integrates the catalytic properties of po rous Pt, a thin catalytic layer, and the spillover effect onto SnO2, agas a dsorptive oxide, with surface-sensitive MOSFETs. The operation characterist ics of the device for the detection of CO are presented as a function of CO gas concentration and operating temperature. The threshold voltage decreas ed 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 less than 1 min at an o perating temperature of 27 degrees C. A model was proposed to explain the o peration. The proposed sensing mechanism of the device is supported well by experimental data.