Optical properties of ordered three-dimensional arrays of structurally confined semiconductors

Three-dimensional arrays of nanometer size clusters have been realised using an opal matrix by filling its voids with CdS and CdSe. From the absorption edge and the luminescence behaviour it is concluded that the average size of the clusters is about 10 nm and that the energy is relaxed via semiconductor nanocluster states and via defect levels in the opal, depending on the strength of the nanocluster-matrix interaction. It is suggested that this class of materials is conducive to the realisation of photonic bandgap structures for visible light and preliminary emission results in opal filled with CdSe support this possibility.