Synthesis of inverse opals

Here we report different simple and inexpensive approaches to the fabrication of inverse opals originated from silica opal templates with sphere size in the range between 0.2 and 1.3 μm. The opal porous lattice is infiltrated with semiconductors (CdS, Ge, Si) as well as polymers by several methods such as chemical vapour deposition, chemical bath deposition, and hydrolysis. Afterwards the template is removed from the composite by a mild chemical etching method giving rise to an inverse opal. The periodicity of the template is chosen to guarantee that photonic gaps or pseudogaps are in the transparency region of the bulk-infiltrated material, which in the case of silicon and germanium can be easily integrated in the existing microelectronic technology.