Highly Sensitive Metal-Insulator-Semiconductor Field-Effect Transistor Sensors for Detecting Carbon Monoxide Gas Using Porous Platinum and Tungsten Oxide Thin Films

A novel device based on a porous Pt–WO 3 metal-insulator-semiconductor field-effect transistor (MISFET) for carbon monoxide (CO) gas sensing has been fabricated. The structure integrates the catalytic properties of porous Pt as a thin catalytic layer, and the spillover effect onto WO 3 film as a gas adsorptive oxide layer, with surface-sensitive MISFET. The operation characteristics of the device for the detection of CO gas are presented as a function of CO gas concentration. The drain current increased rapidly with time depending on the CO gas concentration. It was possible to detect 54 ppm of CO gas with a response time of less than 1 min at 75°C. A model was proposed to explain the operation. The sensing mechanism of the device is supported well by experimental data.