Fabrication and characterization of silver inverse opals

Artificial structures with two- or three-dimensional arrangement of materials (photonic crystals) are being considered in recent days a key structure for the fabrication of advanced optical devices with the potential to substitute present electronics by all-photonic systems in the near future. Special interest has also arisen for their use as chemical sensors and in the fabrication of solar cells. In this work, a fabrication process for silver artificial structures from a colloidal solution of polystyrene spheres is presented. The colloidal spheres are arranged onto a glass substrate to form an artificial opal that is subsequently infiltrated with silver. Additionally, the structural and optical properties of the fabricated structures are studied. The structural characterization of the opals shows good order in the long scale. Reflectance measurements of these samples present a reflection peak centred around 800 nm. SEM images of the silver infiltrated opals show that the infiltration has been carried out successfully. Even so, the optical characterization of the infiltrated samples shows a big intensification of the original reflectivity with a displacement of only few nanometres from the original peak. After the removal of the spheres, the samples show total inversion.