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

• Published in: Thin solid films Vol. 551; pp. 19 - 22
• Main Authors: Niemelä, Janne-Petteri, Yamauchi, Hisao, Karppinen, Maarit
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31.01.2014; Elsevier
• Subjects: Anatase; Atomic layer deposition; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conducting oxide; Conduction; Cross-disciplinary physics: materials science; rheology; Current carriers; Deposition; Electrical properties of specific thin films; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Glass; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Nb-doped TiO2; Niobium; Physics; Surface and interface electron states; Thin films; Titanium dioxide; Transport properties; Vapor phase epitaxy; growth from vapor phase; Nb-doped TiO2; Transport properties; Atomic layer deposition; Conducting oxide; Atomic layer method; Annealing; Electrical conductivity; Anatase; Electrical properties; Polycrystals; Crystal growth from vapors; Thin films; Nb-doped TiO; Physical vapor deposition; Electron mobility; Niobium additions; Titanium oxide; Carrier density; Crystal structure
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2013.11.043

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 1.4×10−3Ωcm. The charge carrier density and electron mobility, as estimated from Seebeck and resistivity measurements, are 0.21–1.1×1021cm−3 and 4.2–22cm2/Vs, respectively. The electrical properties of the ALD-fabricated Nb-doped anatase films are comparable with those of sputter-deposited polycrystalline films on glass. •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.