Titanium and silver contacts on thermally oxidized titanium chip: Electrical and gas sensing properties

► Ti-TiO2 contact is ohmic in all atmospheric conditions and temperatures. ► Ohmic Ag-TiO2 contact becomes highly nonlinear in oxidizing atmosphere. ► Forward biased Ag-TiO2 was experimentally analyzed to result barrier height. ► Reverse current in Ag-TiO2-Ti diode increases 105 times in reducing atmospheres.