Thin film fabrication of nano-porous 12CaO·7Al2O 3 crystal and its conversion into transparent conductive films by light illumination

Yoshitake Toda, Masashi Miyakawa, Katsuro Hayashi, Toshio Kamiya, Masahiro Hirano, Hideo Hosono

Research output: Contribution to journalConference articlepeer-review

43 Citations (Scopus)


Thin film fabrication of crystalline 12CaO·7Al2O 3 (C12A7) with zeolitic structure was examined, and their electrical and optical properties were measured. Polycrystalline thin films were prepared by post-annealing of amorphous films in oxygen atmosphere at temperatures above 800 °C. Choice of substrates was crucial for obtaining single-phase thin films. Although various oxide substrates (single crystals of Al 2O3, Y-stabilized ZrO2, MgO and silica glass) were examined, single-phase films were obtained only for MgO substrates and the other substrates reacted with the CaO component in the films during post-annealing. The optical band gap of C12A7 was evaluated to be 5.9 eV. Hydride ions were incorporated into the film by a thermal treatment in a hydrogen atmosphere at 1200 °C. The resulting transparent thin films were converted into transparent persistent electronic conductors exhibiting an electrical conductivity 6.2×10-1 Scm-1 at 300 K by ultraviolet light illumination. This is the first example of transparent conductive thin film in which conductive areas can be patterned directly by light.

Original languageEnglish
Pages (from-to)309-312
Number of pages4
JournalThin Solid Films
Issue number2
Publication statusPublished - Dec 15 2003
Externally publishedYes
EventProceedings of the 3rd International Symposium on Transparent Oxide - Tokyo, Japan
Duration: Apr 10 2003Apr 11 2003

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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