Photoluminescence of CdSe/ZnS quantum dots in a porous silicon microcavity

It is known that manufacturing and applications of photonic crystals is currently an area of much interest. One of the focuses of special attention in this area is various microcavity (MC) devices. Porous silicon is one of the most promising materials for manufacturing such devices because it is simple to prepare, its optical parameters are precisely controllable, and it has an enormous surface area. This allows to inject different kinds of luminophores into porous silicon MC devices. Apparently, semiconductor quantum dots (QDs) are among the most interesting of them. QDs are characterized by a wide absorbance spectrum, large absorption cross-section, high quantum yield, and excellent photostability. To date, there have been few studies on QD injection into porous silicon photonic structures. In addition, many structures used lack the desired characteristics; the depth of QD penetration also remains a question. This is the first study to analyze the photoluminescence spectrum and kinetics of QDs in a high-quality porous silicon MC. A drastic narrowing of the luminescence spectrum has been observed after QD injection. We have found that the MC morphology considerably affects the penetration of QDs. The kinetics of photoluminescence has also been investigated. Measurements have shown a decrease in the QD characteristic photoluminescence decay time after QD injection into a porous silicon MC compared with the QD photoluminescence decay time in a toluene solution. However, we have not observed a significant difference between the photoluminescence decay times of QDs in an MC and in single-layer porous silicon.