Photonic crystals of titanium dioxide fabricated by swift heavy ions

Koichi Awazu, Makoto Fujimaki, Yoshimichi Ohki, Tetsuro Komatsubara

    Research output: Contribution to journalArticle

    11 Citations (Scopus)

    Abstract

    We have developed a method of fabricating nano-micro-structures in a rutile TiO2 single crystal using swift heavy-ion irradiation that takes advantage of the good etching selectivity induced by ion irradiation. The areas into which ions heavier than Cl and accelerated with MeV-order high energy had been irradiated were readily etched by 20% hydrofluoric acid. By comparison, etching was not observed in pristine TiO2 single crystals. We discovered that the irradiated area could be etched to a depth at which the electronic stopping power of the ion decayed to a value of 6.2 keV/nm. In other words, etching was not observed in TiO2 single crystals possessing electron stopping power below a threshold value of 6.2 keV/nm. We also found that the value of the electronic stopping power first increased, and then decreased with depth in TiO2 single crystals when irradiated with, for example, 84.5 MeV Ca ion. Using this type of beam, the inside of the TiO2 single crystal was selectively etched with 20% hydrofluoric acid, while the top surface of the TiO2 single crystal subjected to irradiation was not etched. It initially appeared that an air gap was created in the region 4-8μm from the top surface subjected to irradiation by 84.5 MeV Ca ion at an accumulated dosage of 3×1014cm-2 followed by etching. The roughness of the new surface created in the single crystal was within 7 nm as measured by atomic force microscopy. X-ray diffraction and high-resolution electron microscope analyses indicated that the irradiated area was composed of amorphous and stressed rutile phases. Both phases were highly soluble in 20% hydrofluoric acid.

    Original languageEnglish
    Pages (from-to)722-729
    Number of pages8
    JournalRadiation Measurements
    Volume40
    Issue number2-6
    DOIs
    Publication statusPublished - 2005 Nov

    Fingerprint

    Photonic crystals
    Heavy ions
    titanium oxides
    Titanium dioxide
    heavy ions
    Single crystals
    photonics
    single crystals
    Hydrofluoric acid
    Etching
    hydrofluoric acid
    stopping power
    crystals
    etching
    Ion bombardment
    ion irradiation
    Power electronics
    rutile
    Ions
    Irradiation

    Keywords

    • Latent track
    • Photonic crystal
    • Rutile
    • Titanium oxide

    ASJC Scopus subject areas

    • Radiation

    Cite this

    Photonic crystals of titanium dioxide fabricated by swift heavy ions. / Awazu, Koichi; Fujimaki, Makoto; Ohki, Yoshimichi; Komatsubara, Tetsuro.

    In: Radiation Measurements, Vol. 40, No. 2-6, 11.2005, p. 722-729.

    Research output: Contribution to journalArticle

    Awazu, Koichi ; Fujimaki, Makoto ; Ohki, Yoshimichi ; Komatsubara, Tetsuro. / Photonic crystals of titanium dioxide fabricated by swift heavy ions. In: Radiation Measurements. 2005 ; Vol. 40, No. 2-6. pp. 722-729.
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