Berlin 2005 – scientific programme

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HL: Halbleiterphysik

HL 62: Photonische Kristalle IV

HL 62.8: Talk

Wednesday, March 9, 2005, 12:30–12:45, TU P164

Structure and Properties of Low-n Mesoporous Silica Films for Optical Applications — •Denan Konjhodzic¹, Helmut Bretinger¹, Siegmund Schröter², and Frank Marlow¹ — ¹Max-Planck-Institut für Kohlenforschung, D-45470 Mülheim an der Ruhr — ²Institut für Physikalische Hochtechnologie, D-07745 Jena

The properties and structure of the mesoporous silica films are investigated. Because of their ultra low refractive index (n = 1.14), these films are used as optical waveguide supports especially for 2D photonic crystals. The films are synthesized by a template-modified sol-gel process using triblock copolymers. A significant dependence of the formed structure on the processing conditions has been revealed allowing an appreciable structure tuning. One set of processing conditions allows the reproducible synthesis of low-n films. They are optically clear, mechanically and chemically resistant, very smooth, and sufficiently thick (1000 nm) with the pore size of 8 nm. Under other processing conditions, a novel sustained lamellar structure remaining stable upon calcination was synthesized.

The films were characterized by angular-dependent interferometry, small angle x-ray scattering, transmission electron microscopy and atomic force microscopy. Onto these films, 2D photonic crystals of different materials, such as polymers (PMMA/DR-1)[1], niob pentoxide and tantal pentoxide have been fabricated. The first investigations of such Ta2O5 and ferroelectric PZT films will be presented.

[1] M. Schmidt et al., Appl. Phys. Lett. 85, 16 (2004)