CO2 and H2 detection with a CHx/porous silicon-based sensor

There has been great interest in the last years in gas sensors based on porous silicon (PS). Recently, a gas sensing device based on a hydrocarbon CHx/porous silicon structure has been fabricated. The porous samples were coated with hydrocarbon groups deposited in a methane argon plasma. We have experimentally demonstrated that the structure can be used for detecting a low concentration of ethylene, ethane and propane gases [Gabouze N, Belhousse S, Cheraga H. Phy State Solidi (C), in press].In this paper, the CHx/PS/Si structure has been used as a sensing material to detect CO2 and H2 gases. The sensitivity of the devices, response time and impedance response to different gas exposures (CO2, H2) have been investigated.The results show that current–voltage and impedance–voltage characteristics are modified by the gas reactivity on the PS/CHx surface and the sensor shows a rapid and reversible response to low concentrations of the gases studied at room temperature.