SCHOTTKY-BARRIER AND CONDUCTIVITY GAS SENSORS BASED UPON PD/SNO2 AND PT/TIO2

Electronic conductivity, mixed conductivity and Schottky-barrier sensors based upon the oxides SnO2 and TiO2 which are modified or contacted by the metals Pd and Pt can be used to detect gases like CO, CH4, H2 and O2. The response signals of these different types of sensors result from changes in surface and bulk conductivities or in Schottky-barrier heights, which are measured using different geometric arrangements of metal (Pd or Pt) contacts. The atomistic understanding of sensing mechanisms and corresponding sensor structures is deduced from comparative spectroscopic and electrical measurements. Our studies show that reliable sensor properties can only be achieved either by forming stable metal/oxide interfaces or by adjusting a stable dopant distribution.