Fabrication and Characterization of 3D Square Spiral Photonic Crystals

Keywords:
photonic crystals, nanostructures thin films, glancing angle deposition, photonic bandgap, square spiral

Abstract:
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