Strong excitonic confinement effect in ZnS and ZnS:Mn nanorods embedded in polycarbonate membrane pores

Abstract

We investigate here the optical properties of excitons in a large array of ordered semiconductor-insulator nanorods. A simple and elegant approach is described to obtain such semiconductor-insulator nanorod structures. Here, we investigate ZnS and ZnS:Mn nanorods of diameters ∼15–100nm crystallized within the pores of polycarbonate membrane. The nanorods confined in the dielectric matrix display strong ultraviolet (UV) excitonic absorption and emission bands in both undoped and Mn2+ doped samples. The data reveal that dielectric confinement rather than dimensional quantization has the significant effect in UV-visible optical absorption and photoluminescence (PL) processes in these semiconductor-insulator nanorods of sizes much wider than the Bohr radius. Interestingly, the emission band associated with Mn2+ transition (∼587–600nm) is also significantly affected by the size effect as well as dielectric discontinuity at the interface. A detailed investigation of PL emission from these embedded ZnS and ZnS:Mn nanorods is also reported.