A new family of gaseous sensors utilizing catalyst-adsorptive oxide-semiconductor MIS structure

Summary form only given. A new family of gaseous sensors utilizing catalyst-adsorptive oxide-semiconductor MIS structures fabricated on silicon has been developed for gas detection. Devices with Pd, Pt, or Ag as catalyst layer deposited on highly sensitive SnO_x or ZnO adsorptive oxide incorporated in the MIS capacitor have been studied for the detection of O₂, H₂, and CO gases. The operating principle of the devices is based on the change in ionic charge density and/or charge redistribution in the adsorptive oxide, SnO _x, or ZnO of the MIS capacitor upon gas adsorption. This leads to a shift in the flatband voltage of the device. The mechanism of O₂ detection is attributed to the dissociation of O₂ molecules on the metal catalyst and the subsequent chemisorption at extrinsic surface states in the adsorptive oxide as negatively charged ions. The detection of H₂ and CO in air ambient is through a reaction with the extrinsic states associated with the chemisorbed oxygen ions