HIGHLY SENSITIVE MOSFET GAS SENSORS WITH POROUS PLATINUM GATE ELECTRODE

Novel gas-sensing devices based on a porous platinum (Pt), gate metal- oxide semiconductor field-effect transistor (MOSFET) have been fabrica ted. The catalytic properties of the porous Pt surface for hydrogen (H -2) enhance the gas detection sensitivity of the MOSFET gas sensor. Th e threshold voltage decreased rapidly with time when the device was ex posed to H-2 gas. It was possible to detect 22 ppm of H-2 gas with a r esponse lime of less than 2 min at a device temperature of 27 degrees C. The gas sensitivity could be enhanced to about 10 times higher than that of an unmodified Pt surface. The device detection mechanism pres ented corresponds well with the experimental data.