Mos and schottky diode gas sensors using transition metal electrodes

MOS and Schottky diode devices with various gate metals and semiconductor substrates were used as sensitive detectors of hydrogen and hydrocarbon based gases. MOS devices were fabricated on n-and p-type silicon substrates with the following gate metals and dielectric materials: Pd-SiO₂, Pd-Ti-SiO₂, Pt-SiO₂, Ni-SiO₂, Pd-Si₃N₄, Pd-Si₃N₄-SiO₂ and Pt-Si₃N₄. In MOS devices with InP substrates, a Pd-Si₃N₄. device was tested. Also, Pdn type InP and Pd-GaAs were used as gaseous detectors in the Schottky barrier configuration. Detection capability of these devices was tested with H₂, CH₄, C₂H₄ and C₄H₁₀ gases. The characteristic parameters of these devices, such as sensitivity limits, adsorption and desorption time constants and linearity of time constants and linearity of response are given and a tentative detection mechanism is presented.