Towards a deeper comprehension of the interaction mechanisms between mesoporous silicon and NO2

The high sensitivity of a room-temperature porous silicon NO2 sensor has re quired an investigation of surface dynamics between NO2 and mesoporous sili con. By means of electrical measurements in gas atmosphere and in-situ FTIR , evidence of a new interaction mechanism strongly affecting the electrical conductivity of the porous silicon (PS) sensors has been found. Absorption bands have been attributed to NO2-, suggesting carrier transfer from the s ilicon wires to NO2, thanks to its high electronic affinity. The models pro posed until now, explaining the high resistivity of mesoporous silicon, str ongly support this interpretation.