Transparent conductive Nb-doped TiO 2 films deposited by reactive dc sputtering using Ti-Nb alloy target, precisely controlled in the transition region using impedance feedback system

Nobuto Oka, Yuta Sanno, Junjun Jia, Shin Ichi Nakamura, Yuzo Shigesato

Research output: Contribution to journalArticle

17 Citations (Scopus)


In this study, a stable reactive sputtering process using a Ti-Nb alloy target was achieved by applying a plasma impedance feedback system. High-quality transparent conductive Nb-doped TiO 2 (Nb:TiO 2 ) films were fabricated with high reproducibility. The films were deposited on unheated substrate and subsequently annealed at 873 K under vacuum conditions (below 6.0 × 10 -4 Pa) for 1 h. During reactive sputtering, the feedback system precisely controlled the oxidation of the target surface in the so-called transition region. The post-annealing process yielded polycrystalline Nb:TiO 2 films whose lattice defects decreased with increasing Nb concentration. An extremely low resistivity (7.2 × 10 -4 Ω cm) was achieved for Nb:TiO 2 film with 60-70% transmittance in the visible region. The reactive sputtering using Ti-Nb alloys is considered to be a strong candidate for industrial-scale thin-film deposition. Furthermore, it can also control the metal-oxygen stoichiometry of Nb:TiO 2 films precisely to achieve desirable properties for each industrial application.

Original languageEnglish
Pages (from-to)551-556
Number of pages6
JournalApplied Surface Science
Publication statusPublished - 2014 May 15
Externally publishedYes



  • Orientation
  • Reactive sputtering
  • Thin films
  • Ti-Nb alloy target

ASJC Scopus subject areas

  • Surfaces, Coatings and Films

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