GAS SENSITIVITIES OF SILICON MIS CAPACITORS INCORPORATED WITH CATALYST AND ADSORPTIVE OXIDE LAYERS

A new family of gas sensors based on catalyst-adsorptive oxide-Si3N4-SiO2-Si-Al MIS capacitor has been developed. The structure integrates the catalytic properties of Pd, Pt, or Ag as a thin catalyst layer, and the gas sensing properties of SnO(x) or ZnO as a gas adsorptive oxide with a surface sensitive silicon MIS capacitor. The choice of catalyst layer and adsorptive oxide employed in the structure modifies the gas sensing characteristics: gas selectivity, sensitivity, activation energy, and reaction rate constant. Moreover, the sensors can detect O2, H-2, and CO gases at a much lower temperature than conventional solid state gas detectors.