Anisotropic electrical resistivity during annealing of oriented columnar titanium films

• We examine anisotropic electrical resistivity versus temperature of titanium films.
• Annealing in air leads to a gradual metal-to-dielectric transition.
• Anisotropic coefficient exceeds a decade after the annealing treatment.
• Oxidation is favored by the porous structure the GLAD films.

We report on the evolution of anisotropic electrical resistivity versus temperature of titanium thin films. An oriented titanium film (1 μm thick) is sputter deposited by GLancing Angle Deposition (GLAD) using an incident angle α=80° of the particle flux. Two parallel Ti electrodes cover this GLAD film. We measure the components of the conductivity tensor by the van der Pauw method during an annealing treatment in air ranging from 298 to 873 K. The average DC electrical resistivity ρ changes from 6.03×10−6 to more than 2.40×10−1 Ωm with the increasing temperature. The anisotropy ratio is A=1.39 before annealing and reaches 12.4 for the highest temperatures. This enhanced anisotropy is interpreted assuming the oxidation of the porous GLAD titanium film.