Porous silver-TiO2 Schottky-type chemical sensor fabricated on thermally oxidised titanium

The fabrication and characterisation of silver-rutile junctions, formed by sintering silver particles on a thermally oxidised titanium single crystal, are reported. Operating in air at elevated temperatures, these devices were low leakage current and high barrier Schottky diodes, while in highly reducing atmospheres they behaved as ohmic contacts. This reversible transition afforded a broad dynamic range and high sensitivity for chemical detection. The reverse current increased ~10 times when 1% butanol vapour was introduced to the surrounding clean air. The fabrication method described can also be employed to make other noble metal-rutile diodes.