Conducting Nb-doped TiO2 thin films fabricated with an atomic layer deposition technique

• Atomic layer deposition was used to grow conducting Ti1 − xNbxO2 thin films.
• Excellent control of the film composition x was achieved.
• Resistivity and the Seebeck coefficient varied systematically with x.
• At x = 0.25, maximum in c-axis orientation and minimum in resistivity were observed.
• The films appear as promising materials for large area, conformal TCO coatings.

Highly conducting Ti1 − xNbxO2 thin films have been grown on glass substrates from TiCl4, Nb(OEt)5 and H2O with an atomic layer deposition (ALD) technique. The films become electrically conducting and crystallize with the anatase structure upon a reductive post-deposition annealing. A highly c-axis oriented Ti0.75Nb0.25O2 film exhibits room-temperature resistivity as low as 1.4 × 10− 3 Ω cm. The charge carrier density and electron mobility, as estimated from Seebeck and resistivity measurements, are 0.21–1.1 × 1021 cm− 3 and 4.2–22 cm2/Vs, respectively. The electrical properties of the ALD-fabricated Nb-doped anatase films are comparable with those of sputter-deposited polycrystalline films on glass.