From planar defect in opal to planar defect in inverse opal

We demonstrate a facile method of fabricating opal and inverse opal structures with a planar defect. A single layer of silica beads was embedded into polystyrene opals by combining an inward-growing self-assembly method with spin-coating technique. After the infiltration of silica followed by the removal of the polystyrene beads by calcination, an inverted structure was obtained. The silica beads were connected together by the infiltrated silica, thus a solid silica phase with the silica beads as a planar defect embedded in the inverse silica opal was obtained. The thickness of the defect layer can be adjusted by changing the size of the silica beads. Scanning electron microscope images showed the good quality of the crystal and the uniformity of the defect layer. Optical transmission spectra indicated the existence of a defect state induced by the defect layer in both the opal and inverse opal structures. High-cost techniques such as lithography and chemical vapor deposition are not involved in the fabrication of inverse opals with planar defects