Structural change induced in TiO2 by swift heavy ions and its application to three-dimensional lithography

Ken ichi Nomura, Tetsuya Nakanishi, Yoshihiro Nagasawa, Yoshimichi Ohki, Koichi Awazu*, Makoto Fujimaki, Naoto Kobayashi, Satoshi Ishii, Kunihiro Shima


研究成果: Article査読

40 被引用数 (Scopus)


A rutile TiO2 single crystal was irradiated by heavy ions with a high energy of the order of several tens of MeV. A good etching selectivity, where only the irradiated surface is well etched by hydrofluoric acid is induced by the irradiation. Through x-ray diffraction and high-resolution electron microscopy, it became clear that the irradiated region lost crystallization. It is considered that this amorphous region and the surrounding region are dissolved in hydrofluoric acid. Through the calculation of the ion energy, it was found that the etching always stopped at the depth where the electronic stopping power of the ion decayed to a critical value of 6.2 keV/nm, regardless of the ion species in the case of I, Br, Cu, and Ti ions. However, in the case of Ca ions with energies higher than about 72 MeV or Cl ions with energies higher than about 77 MeV, the irradiated top surface was not etched with hydrofluoric acid, but the inside surface several μm deep from the irradiated surface was etched. A calculation shows that the critical factor which determines whether the irradiated surface can be etched or not is the lateral energy density on the surface deposited by ions. The etched surface observed by atomic force microscopy is very smooth with a roughness of the order of nm. Therefore, a combination of ion irradiation and etching can be used as a novel fabrication method of nanostructures in rutile.

ジャーナルPhysical Review B - Condensed Matter and Materials Physics
出版ステータスPublished - 2003 8月 1

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • 凝縮系物理学


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