Surface interaction mechanisms in metal-oxide semiconductors for alkane detection

Gas sensors based on semiconductive materials have gained an increasing interest, thanks to their advantageous characteristics. However, their intrinsic lack of selectivity made research in this eld to come to a standstill. Such devices are mainly applied to environmental and indoor monitoring. A clearer analysis of surface reaction phenomena is the key to nd a solution to the problem of limited selectivity. This approach has been applied to gases of great interest, such as alkanes. The main aim of this dissertation is to clarify some theoretical and experimental aspects related to the sensing processes of metal-oxide semiconductors. Temperature programmed desorption techniques were chosen to investigate thermodynamic properties of nanostructured powders. Readsorption occurred for almost all the states observed, representing an advantage for sensing mechanism. Conduction measurements performed on thick film sensors resulted in positive responses under dry and wet conditions and in presence of ethanol. Concrete indications about the building of a reliable and efficient device were suggested.