Fabrication and Characterization of 3D Square Spiral Photonic Crystals
M.O. Jensen, M.A. Summers and M.J. Brett
University of Alberta, CA
photonic crystals, nanostructures thin films, glancing angle deposition, photonic bandgap, square spiral
Three-dimensional photonic crystals can be fabricated using the glancing angle thin film deposition technique (GLAD). These nanostructured thin films consist of a periodic array of micrometer-sized silicon square spirals, as proposed by O. Toader and S. John. The GLAD fabrication process uses advanced substrate motion and oblique incidence deposition. These nanostructures are grown with in-plane periodicity using a pre-patterned substrate consisting of a tetragonal array of relief structures. The arrays can be fabricated using a number of lithographic techniques. Direct-write lithography provides the significant advantage of easy parameter modification, since no master is required. We demonstrate the use of laser direct-write lithography (LDL) and electron beam lithography (EBL) to fabricate silicon square spiral photonic crystals with a complete three-dimensional photonic band gap. Additionally, these techniques enable the scaling down of photonic crystal dimensions to produce a photonic bandgap in the near infra-red region. Finally, we investigate the process of inverting the square spiral structure to produce the corresponding inverse structure with a larger predicted bandgap. This involves fabricating a template square spiral film from a non-silicon material, filling the film with silicon, and finally removing the original template with an isotropic etch process.
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Nanotech 2005 Conference Program Abstract