Flash annealing influence on structural and electrical properties of TiO2/TiO/Ti periodic multilayers

• TiO2/TiO/Ti periodic multilayers deposited by reactive gas pulsing sputtering.
• Periodic multilayers are always observed after flash annealing.
• Electrical properties of multilayers are modified by thermal treatments.
• Film temperature coefficient of resistance tuned from positive to negative.

Multilayered structures with a 40 nm period composed of titanium and two different titanium oxides, TiO and TiO2, were accurately produced by DC magnetron sputtering using the reactive gas pulsing process. These multilayers were sputtered onto Al2O3 sapphire to avoid substrate compound diffusion during flash annealing (ranging from 350 °C to 550 °C). Structure and composition of these periodic TiO2/TiO/Ti stacks were investigated by X-ray diffraction, X-ray photoemission spectroscopy and transmission electronic microscopy techniques. Two crystalline phases α-Ti and fcc-TiO were identified in the metallic-rich sub-layers whereas the oxygen-rich ones were composed of a mixture of amorphous and rutile TiO2 phase. DC electrical resistivity ρ measured for temperatures ranging from 25 to 200 °C was influenced by the thermal treatments. The temperature coefficients of resistance of these periodic TiO2/TiO/Ti multilayers were modified from 11.7 × 10− 04 to − 8.81 × 10− 04 K− 1. Local changes of crystallinity were reported and the resistivity responses of these annealed films could be linked to the typical electrical behavior of a metal–oxide mixture.