A trigonal lattice of macropores in silicon is a favourite system for the study of 2D photonic crystals in the infrared spectral region. Continuing the work of U. Gruning and V. Lehmann structures with a pitch down to 1,5 microns could be prepared in the past. We show transmission measurements of these crystals exibiting photonic bandgaps in the Mid-IR (wavelength 3-5microns) [1]. The aim of scaling down the structures to telecommunication wavelengths could be attained. Pictures of these newly fabricated pore arrays providing photonic bandgaps in the Near-IR (around a wavelenght of 1,3 microns) will be presented.
Beyond the 2-dimensional periodicity of the pore arrays, macroporous silicon can be used to create 3D periodic dielectric structures. One possibility is the „Kielovite" [2].
Another one is the periodic modulation of the pore diameter with the depth. That leads to a periodic dielectric constant in the direction of the pore axis. Combined with the 2D trigonal pore lattice, 3D periodic dielectric structures could be accomplished in this way. The features of these structures have been investigated by FTIR-Spectroscopy.
[1] A. Birner, U. Gruning, S. Ottow, A. Schneider, F. Muller, V. Lehmann, H. Foll, U. Gosele
Phys. Stat. Sol. 165, 111 (1998)
[2] M. Christophersen, J. Carstensen, A. Feuerhake, H. Foll
Materials Science and Engineering B 69-70, 194 (2