Independent control of phases and defects in TiO2thin films for functional transistor channels

Takeaki Yajima, Go Oike, Tomonori Nishimura, Akira Toriumi

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


TiO2has various inherent advantages in practical devices: chemical stability, non-toxicity, and abundance on earth, as highlighted in a range of applications of TiO2surfaces in photocatalysis/optoelectronics. However, the application of TiO2to three-terminal devices has been limited; for example, TiO2-channel transistors, which may potentially modulate the TiO2surface properties by electrostatic back gating, has suffered from low field-effect mobility (μFE< 1 cm2V−1s−1) irrespective of fabrication methods. The major challenge is to control phases (rutile/anatase) and defects (oxygen vacancy) simultaneously in TiO2thin films. Here, we achieved μFE∼ 10 cm2V−1s−1in TiO2-channel transistors, one order higher than before and even comparable to InGaZnO channels. The major improvement is the independent control of phases and defects in TiO2thin films; we formed short-range order of anatase phase in the amorphous deposition, and minimized the number of defects in the subsequent thermal treatment. Besides, we showed this independent control of phases and defects are underpinned by excellent thermal stability of TiO2/SiO2interfaces. These results demonstrate TiO2can be a transistor channel with a reasonable μFEand ON/OFF ratio (>6 orders), not only changing the conventional image of this material, but also promising new functionalities based on unique properties of TiO2.

Original languageEnglish
Pages (from-to)2196-2202
Number of pages7
JournalPhysica Status Solidi (A) Applications and Materials Science
Issue number8
Publication statusPublished - Aug 1 2016
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering
  • Materials Chemistry


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