JJAP Conference Proceedings

JJAP Conf. Proc. 2, 011205 (2014) doi:10.7567/JJAPCP.2.011205

Comparison study of mesoporous thin films characterized by low-energy positron lifetime spectroscopy and flow-type ellipsometric porosimetry

Shigeru Yoshimoto1, Kenji Ito2, Hiroyuki Hosomi1, Yoshihiro Takai1

  1. 1Toray Research Center, Inc., Otsu 520-8567, Japan
  2. 2National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565, Japan
  • Received May 29, 2014
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Flow-type ellipsometric porosimetry (EP) and low-energy positron annihilation lifetime spectroscopy (PALS) were applied to the pore characterization for two types of nanoporous methyl silsesquioxane thin films fabricated on silicon wafers, in order to examine the consistency between the porosities characterized by both techniques. The sizes of the mesopores in the films were evaluated from the respective pore size distributions, obtained using flow-type EP from n-hexane adsorption isotherms at 26 °C based on the Barrett–Joyner–Halenda (BJH) model, while the longest-lived ortho-positronium (o-Ps) lifetimes for the films were measured using low-energy PALS at an incident positron energy of 1.5 keV. The relationship between the pore size and the o-Ps lifetime is discussed in comparison with previously reported measurements for various porous substances.

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