Synthesis, characterization and modelling of silicon based opals

Artificial opals, consisting of silica nanospheres ordered into a fcc lattices, were grown with good control of the orientation and sphere size. Such structures were impregnated by amorphous silicon and successively inverted by template removal in order to obtain photonic crystals with high refractive index contrast. The analysis of the photonic bandgap was carried out by means of reflectance and photoluminescence spectra, corroborated by calculations of photonic bands as well as reflection spectra performed by a scattering matrix method.