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

TLDR: In this article, a thermally oxidized titanium chip was used to evaluate the properties of the TiO 2 -Ti and Ag-TiO 2-Ti structures at different biasing, thermal and atmospheric conditions.

Abstract: Ti–TiO 2 structure has been utilized in the fabrication of many TiO 2 -based devices such as solar cells, electrocatalytic electrodes and noble metal–TiO 2 –Ti chemical sensors. While the ohmic behaviour of Ti–TiO 2 is assumed in the description of many TiO 2 -based devices, direct experimental evaluation has not yet been carried out. We have fabricated Ti–TiO 2 –Ti and Ag–TiO 2 –Ti structures on a thermally oxidized titanium chip and assessed their electronic behaviours at different biasing, thermal and atmospheric conditions. The junction areas at the opposite sides of the Ti–TiO 2 –Ti structure were different and the linearity of the I–V characteristics of the structure, at both biasing directions, approved the ohmicity assumed. This was compared to the behaviour of Ag–TiO 2 junction which varied from a high energy barrier Schottky diode to an ohmic contact, depending on the composition of the surrounding atmosphere. It was established that the ionic current due to the field assisted silver ion migration in the forward biased device causes the behaviour of the Ag–TiO 2 junction to deviate from that of a Schottky diode.